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    Inhibition of TRAF6 ubiquitin-ligase activity by PRDX1 leads to inhibition of NFKB activation and autophagy activation. Min Yoon,Kim Mi-Jeong,Lee Sena,Chun Eunyoung,Lee Ki-Young Autophagy TRAF6 (TNF receptor associated factor 6) plays a pivotal role in NFKB activation and macroautphagy/autophagy activation induced by TLR4 (toll like receptor 4) signaling. The objective of this study was to determine the functional role of PRDX1 (peroxiredoxin 1) in NFKB activation and autophagy activation. PRDX1 interacted with the ring finger domain of TRAF6 and inhibited its ubiquitin-ligase activity. The inhibition on TRAF6 ubiquitin-ligase activity by PRDX1 induced the suppression of ubiquitination of an evolutionarily conserved signaling intermediate in Toll pathways (ECSIT) essential for NFKB activation and BECN1 (beclin 1) required for autophagy activation. An inhibitory effect of PRDX1 on TRAF6 was clearly evidenced in PRDX1-knockdown (PRDX1KD) THP-1, PRDX1KD MDA-MB-231, and PRDX1KD SK-HEP-1 cells. PRDX1KD THP-1 cells showed increases of NFKB activation, pro-inflammatory cytokine production, NFKB-dependent gene expression induced by TLR4 stimulation, and resistance against Salmonella typhimurium infection. Additionally, migration and invasion abilities of PRDX1KD MDA-MB-231 and PRDX1KD SK-HEP-1 cancer cells were significantly enhanced compared to those of control cancer cells. Taken together, these results suggest that PRDX1 negatively regulates TLR4 signaling for NFKB activation and autophagy functions such as bactericidal activity, cancer cell migration, and cancer cell invasion by inhibiting TRAF6 ubiquitin-ligase activity. ABBREVIATIONS:3-MA: 3-methyladenine; BECN1: beclin 1; CHUK/IKKA: conserved helix-loop-helix ubiquitous kinase; ECSIT: ECSIT signalling integrator; ELISA: enzyme-linked immunosorbent assay; NFKB: nuclear factor kappa-light-chain-enhancer of activated B cells; IB: immunoblotting; IKBKB/IKKB: inhibitor of nuclear factor kappa B kinase subunit beta; IL1B: interleukin 1 beta; IL6: interleukin 6; IP: immunoprecipitation; LPS: lipopolysaccharide; MAP1LC3/LC3: microtuble associated protein 1 light chain 3; MAP3K7/TAK1: mitogen-activated protein kinase kinase kinase 7; MAPK14/p38: mitogen-activated protein kinase 14; mROS: mitochondrial reactive oxygen species; PRDX1: peroxiredoxin 1; PRDX6: peroxiredoxin 6; RELA/p65: RELA proto-oncogene, NF-kB subunit; TRAF6 TNF: receptor associated factor 6. 10.1080/15548627.2018.1474995
    T cells instruct myeloid cells to produce inflammasome-independent IL-1β and cause autoimmunity. Nature immunology The cytokine interleukin (IL)-1β is a key mediator of antimicrobial immunity as well as autoimmune inflammation. Production of IL-1β requires transcription by innate immune receptor signaling and maturational cleavage by inflammasomes. Whether this mechanism applies to IL-1β production seen in T cell-driven autoimmune diseases remains unclear. Here, we describe an inflammasome-independent pathway of IL-1β production that was triggered upon cognate interactions between effector CD4 T cells and mononuclear phagocytes (MPs). The cytokine TNF produced by activated CD4 T cells engaged its receptor TNFR on MPs, leading to pro-IL-1β synthesis. Membrane-bound FasL, expressed by CD4 T cells, activated death receptor Fas signaling in MPs, resulting in caspase-8-dependent pro-IL-1β cleavage. The T cell-instructed IL-1β resulted in systemic inflammation, whereas absence of TNFR or Fas signaling protected mice from CD4 T cell-driven autoimmunity. The TNFR-Fas-caspase-8-dependent pathway provides a mechanistic explanation for IL-1β production and its consequences in CD4 T cell-driven autoimmune pathology. 10.1038/s41590-019-0559-y
    JAK inhibitors in autoinflammation. Hoffman Hal M,Broderick Lori The Journal of clinical investigation Interferonopathies are a subset of autoinflammatory disorders with a prominent type I IFN gene signature. Treatment of these patients has been challenging, given the lack of response to common autoinflammatory therapeutics including IL-1 and TNF blockade. JAK inhibitors (Jakinibs) are a family of small-molecule inhibitors that target the JAK/STAT signaling pathway and have shown clinical efficacy, with FDA and European Medicines Agency (EMA) approval for arthritic and myeloproliferative syndromes. Sanchez and colleagues repurposed baricitinib to establish a significant role for JAK inhibition as a novel therapy for patients with interferonopathies, demonstrating the power of translational rare disease research with lifesaving effects. 10.1172/JCI121526
    Inflammasome activation negatively regulates MyD88-IRF7 type I IFN signaling and anti-malaria immunity. Yu Xiao,Du Yang,Cai Chunmei,Cai Baowei,Zhu Motao,Xing Changsheng,Tan Peng,Lin Meng,Wu Jian,Li Jian,Wang Mingjun,Wang Helen Y,Su Xin-Zhuan,Wang Rong-Fu Nature communications The inflammasome plays a critical role in inflammation and immune responses against pathogens. However, whether or how inflammasome activation regulates type I interferon (IFN-I) signaling in the context of malaria infection remain unknown. Here we show mice deficient in inflammasome sensors AIM2, NLRP3 or adaptor Caspase-1 produce high levels of IFN-I cytokines and are resistant to lethal Plasmodium yoelii YM infection. Inactivation of inflammasome signaling reduces interleukin (IL)-1β production, but increases IFN-I production. Mechanistically, we show inflammsome activation enhances IL-1β-mediated MyD88-TRAF3-IRF3 signaling and SOCS1 upregulation. However, SOCS1 inhibits MyD88-IRF7-mediated-IFN-I signaling and cytokine production in plasmacytoid dendritic cells. By contrast, ablation of inflammsome components reduces SOCS1 induction, and relieves its inhibition on MyD88-IRF7-dependent-IFN-I signaling, leading to high levels of IFN-α/β production and host survival. Our study identifies a previously unrecognized role of inflammasome activation in the negative regulation of IFN-I signaling pathways and provides potential targets for developing effective malaria vaccines. 10.1038/s41467-018-07384-7
    Hydroxychloroquine inhibits proinflammatory signalling pathways by targeting endosomal NADPH oxidase. Müller-Calleja Nadine,Manukyan Davit,Canisius Antje,Strand Dennis,Lackner Karl J Annals of the rheumatic diseases OBJECTIVES:Hydroxychloroquine (HCQ) has been used for decades to treat patients with rheumatic diseases, for example, systemic lupus erythematosus (SLE), rheumatoid arthritis or the antiphospholipid syndrome (APS). We hypothesise that HCQ might target endosomal NADPH oxidase (NOX), which is involved in the signal transduction of cytokines as well as antiphospholipid antibodies (aPL). METHODS:For in vitro experiments, monocytic cells were stimulated with tumour necrosis factor α (TNFα), interleukin-1β (IL-1β) or a human monoclonal aPL and the activity of NOX was determined by flow cytometry. The expression of genes known to be induced by these stimuli was quantified by quantitative reverse transcription PCR. Live cell imaging was performed by confocal laser scanning microscopy. Finally, the effects of HCQ on NOX-induced signal transduction were analysed in an in vivo model of venous thrombosis. RESULTS:HCQ strongly reduces or completely prevents the induction of endosomal NOX by TNFα, IL-1β and aPL in human monocytes and MonoMac1 cells. As a consequence, induction of downstream genes by these stimuli is reduced or abrogated. This effect of HCQ is not mediated by direct interference with the agonists but by inhibiting the translocation of the catalytic subunit of NOX2 (gp91phox) into the endosome. In vivo, HCQ protects mice from aPL-induced and NOX2-mediated thrombus formation. CONCLUSIONS:We describe here a novel mechanism of action of HCQ, that is, interference with the assembly of endosomal NOX2. Since endosomal NOX2 is involved in many inflammatory and prothrombotic signalling pathways, this activity of HCQ might explain many of its beneficial effects in rheumatic diseases including the APS. 10.1136/annrheumdis-2016-210012
    CCL21-CCR7 axis in RA: linking inflammation and bone erosion. McHugh Jessica Nature reviews. Rheumatology 10.1038/s41584-019-0296-5
    Fc gamma receptor-TLR cross-talk elicits pro-inflammatory cytokine production by human M2 macrophages. Vogelpoel Lisa T C,Hansen Ivo S,Rispens Theo,Muller Femke J M,van Capel Toni M M,Turina Maureen C,Vos Joost B,Baeten Dominique L P,Kapsenberg Martien L,de Jong Esther C,den Dunnen Jeroen Nature communications M2 macrophages suppress inflammation in numerous disorders, including tumour formation, infection and obesity. However, the exact role of M2 macrophages in the context of several other diseases is still largely undefined. We here show that human M2 macrophages promote inflammation instead of suppressing inflammation on simultaneous exposure to complexed IgG (c-IgG) and TLR ligands, as occurs in the context of diseases such as rheumatoid arthritis (RA). c-IgG-TLR ligand co-stimulation of M2 macrophages selectively amplifies production of pro-inflammatory cytokines TNF-α, IL-1β and IL-6 and promotes Th17 responses, which all play a critical role in RA pathology. Induction of pro-inflammatory cytokines on c-IgG co-stimulation mainly depends on Fc gamma receptor IIa (FcγRIIa), which selectively amplifies cytokine gene transcription and induces caspase-1 activation. These data indicate that FcγR-TLR cross-talk may be targeted for treatment to attenuate inflammation in RA, by restoring the anti-inflammatory function of M2 macrophages. 10.1038/ncomms6444
    Transcription factor NFAT5 promotes macrophage survival in rheumatoid arthritis. Choi Susanna,You Sungyong,Kim Donghyun,Choi Soo Youn,Kwon H Moo,Kim Hyun-Sook,Hwang Daehee,Park Yune-Jung,Cho Chul-Soo,Kim Wan-Uk The Journal of clinical investigation Defective apoptotic death of activated macrophages has been implicated in the pathogenesis of rheumatoid arthritis (RA). However, the molecular signatures defining apoptotic resistance of RA macrophages are not fully understood. Here, global transcriptome profiling of RA macrophages revealed that the osmoprotective transcription factor nuclear factor of activated T cells 5 (NFAT5) critically regulates diverse pathologic processes in synovial macrophages including the cell cycle, apoptosis, and proliferation. Transcriptomic analysis of NFAT5-deficient macrophages revealed the molecular networks defining cell survival and proliferation. Proinflammatory M1-polarizing stimuli and hypoxic conditions were responsible for enhanced NFAT5 expression in RA macrophages. An in vitro functional study demonstrated that NFAT5-deficient macrophages were more susceptible to apoptotic death. Specifically, CCL2 secretion in an NFAT5-dependent fashion bestowed apoptotic resistance to RA macrophages in vitro. Injection of recombinant CCL2 into one of the affected joints of Nfat5+/- mice increased joint destruction and macrophage infiltration, demonstrating the essential role of the NFAT5/CCL2 axis in arthritis progression in vivo. Moreover, after intra-articular injection, NFAT5-deficient macrophages were more susceptible to apoptosis and less efficient at promoting joint destruction than were NFAT5-sufficient macrophages. Thus, NFAT5 regulates macrophage survival by inducing CCL2 secretion. Our results provide evidence that NFAT5 expression in macrophages enhances chronic arthritis by conferring apoptotic resistance to activated macrophages. 10.1172/JCI87880
    Melatonin inhibits the sphingosine kinase 1/sphingosine-1-phosphate signaling pathway in rabbits with fulminant hepatitis of viral origin. Crespo Irene,San-Miguel Beatriz,Sánchez Diana I,González-Fernández Bárbara,Álvarez Marcelino,González-Gallego Javier,Tuñón María J Journal of pineal research The sphingosine kinase (SphK)1/sphingosine-1-phosphate (S1P) pathway is involved in multiple biological processes, including liver diseases. This study investigate whether modulation of the SphK1/S1P system associates to the beneficial effects of melatonin in an animal model of acute liver failure (ALF) induced by the rabbit hemorrhagic disease virus (RHDV). Rabbits were experimentally infected with 2 × 10(4) hemagglutination units of a RHDV isolate and received 20 mg/kg of melatonin at 0, 12, and 24 hr postinfection. Liver mRNA levels, protein concentration, and immunohistochemical labeling for SphK1 increased in RHDV-infected rabbits. S1P production and protein expression of the S1PR1 receptor were significantly elevated following RHDV infection. These effects were significantly reduced by melatonin. Rabbits also exhibited increased expression of toll-like receptor (TLR)4, tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, nuclear factor-kappa B (NF-κB) p50 and p65 subunits, and phosphorylated inhibitor of kappa B (IκB)α. Melatonin administration significantly inhibited those changes and induced a decreased immunoreactivity for RHDV viral VP60 antigen in the liver. Results obtained indicate that the SphK1/S1P system activates in parallel to viral replication and the inflammatory process induced by the virus. Inhibition of the lipid signaling pathway by the indole reveals novel molecular pathways that may account for the protective effect of melatonin in this animal model of ALF, and supports the potential of melatonin as an antiviral agent. 10.1111/jpi.12335
    Tetrahedral framework nucleic acids promote scarless healing of cutaneous wounds via the AKT-signaling pathway. Zhu Junyao,Zhang Mei,Gao Yang,Qin Xin,Zhang Tianxu,Cui Weitong,Mao Chenchen,Xiao Dexuan,Lin Yunfeng Signal transduction and targeted therapy While the skin is considered the first line of defense in the human body, there are some vulnerabilities that render it susceptible to certain threats, which is an issue that is recognized by both patients and doctors. Cutaneous wound healing is a series of complex processes that involve many types of cells, such as fibroblasts and keratinocytes. This study showed that tetrahedral framework nucleic acids (tFNAs), a type of self-assembled nucleic-acid material, have the ability to promote keratinocyte(HaCaT cell line) and fibroblast(HSF cell line) proliferation and migration in vitro. In addition, tFNAs increased the secretion of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) in HSF cells and reduced the production of tumor necrosis factor-alpha (TNF-α) and interleukin-1 beta (IL-1β) in HaCaT cells by activating the AKT-signaling pathway. During in vivo experiments, tFNA treatments accelerated the healing process in skin wounds and decreased the development of scars, compared with the control treatment that did not use tFNAs. This is the first study to demonstrate that nanophase materials with the biological features of nucleic acids accelerate the healing of cutaneous wounds and reduce scarring, which indicates the potential application of tFNAs in skin tissue regeneration. 10.1038/s41392-020-0173-3
    Melatonin attenuates choroidal neovascularization by regulating macrophage/microglia polarization via inhibition of RhoA/ROCK signaling pathway. Xu Yue,Cui Kaixuan,Li Jia,Tang Xiaoyu,Lin Jianqiang,Lu Xi,Huang Rong,Yang Boyu,Shi Yuxun,Ye Dan,Huang Jingjing,Yu Shanshan,Liang Xiaoling Journal of pineal research Choroidal neovascularization (CNV) is an important characteristic of advanced wet age-related macular degeneration (AMD) and leads to severe visual impairment among elderly patients. Previous studies have demonstrated that melatonin induces several biological effects related to antioxidation, anti-inflammation, and anti-angiogenesis. However, the role of melatonin in CNV, and its underlying mechanisms, has not been investigated thus far. In this study, we found that melatonin administration significantly reduced the scale and volume of CNV lesions, suppressed vascular leakage, and inhibited the capacity of vascular proliferation in the laser-induced mouse CNV model. Additionally, the results also show that the melatonin-treated retinal microglia in the laser-induced mice exhibited enhanced expression of M1-type markers, such as iNOS, CCL-3, CCL-5, and TNF-α, as well as decreased production of M2-type markers, such as Arg-1, Fizz-1, IL-10, YM-1, and CD206, indicating that melatonin switched the macrophage/microglia polarization from pro-angiogenic M2 phenotype to anti-angiogenic M1 phenotype. Furthermore, the RhoA/ROCK signaling pathway was activated during CNV formation, yet was suppressed after an intraperitoneal injection of melatonin. In conclusion, melatonin attenuated CNV, reduced vascular leakage, and inhibited vascular proliferation by switching the macrophage/microglia polarization from M2 phenotype to M1 phenotype via inhibition of RhoA/ROCK signaling pathway in CNV. This suggests that melatonin could be a novel agent for the treatment of AMD. 10.1111/jpi.12660
    Disrupted nocturnal melatonin in autism: Association with tumor necrosis factor and sleep disturbances. da Silveira Cruz-Machado Sanseray,Guissoni Campos Leila Maria,Fadini Cintia Cristina,Anderson George,Markus Regina P,Pinato Luciana Journal of pineal research Sleep disturbances, abnormal melatonin secretion, and increased inflammation are aspects of autism spectrum disorder (ASD) pathophysiology. The present study evaluated the daily urinary 6-sulfatoxymelatonin (aMT6s) excretion profile and the salivary levels of tumor necrosis factor (TNF) and interleukin-6 (IL-6) in 20 controls and 20 ASD participants, as well as correlating these measures with sleep disturbances. Although 60% of ASD participants showed a significant night-time rise in aMT6s excretion, this rise was significantly attenuated, compared to controls (P < .05). The remaining 40% of ASD individuals showed no significant increase in nocturnal aMT6s. ASD individuals showed higher nocturnal levels of saliva TNF, but not IL-6. Dysfunction in the initiation and maintenance of sleep, as indicated by the Sleep Disturbance Scale for Children, correlated with night-time aMT6s excretion (r = -.28, P < .05). Dysfunction in sleep breathing was inversely correlated with aMT6s (r = -.31, P < .05) and positively associated with TNF level (r = .42, P < .01). Overall such data indicate immune-pineal axis activation, with elevated TNF but not IL-6 levels associated with disrupted pineal melatonin release and sleep dysfunction in ASD. It is proposed that circadian dysregulation in ASD is intimately linked to heightened immune-inflammatory activity. Such two-way interactions of the immune-pineal axis may underpin many aspects of ASD pathophysiology, including sleep disturbances, as well as cognitive and behavioral alterations. 10.1111/jpi.12715
    Autophagy: controlling cell fate in rheumatic diseases. Rockel Jason S,Kapoor Mohit Nature reviews. Rheumatology Autophagy, an endogenous process necessary for the turnover of organelles, maintains cellular homeostasis and directs cell fate. Alterations to the regulation of autophagy contribute to the progression of various rheumatic diseases, including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), osteoarthritis (OA) and systemic sclerosis (SSc). Implicit in the progression of these diseases are cell-type-specific responses to surrounding factors that alter autophagy: chondrocytes within articular cartilage show decreased autophagy in OA, leading to rapid cell death and cartilage degeneration; fibroblasts from patients with SSc have restricted autophagy, similar to that seen in aged dermal fibroblasts; fibroblast-like synoviocytes from RA joints show altered autophagy, which contributes to synovial hyperplasia; and dysregulation of autophagy in haematopoietic lineage cells alters their function and maturation in SLE. Various upstream mechanisms also contribute to these diseases by regulating autophagy as part of their signalling cascades. In this Review, we discuss the links between autophagy, immune responses, fibrosis and cellular fates as they relate to pathologies associated with rheumatic diseases. Therapies in clinical use, and in preclinical or clinical development, are also discussed in relation to their effects on autophagy in rheumatic diseases. 10.1038/nrrheum.2016.92
    Protein Arginine Deiminases (PADs): Biochemistry and Chemical Biology of Protein Citrullination. Mondal Santanu,Thompson Paul R Accounts of chemical research Proteins are well-known to undergo a variety of post-translational modifications (PTMs). One such PTM is citrullination, an arginine modification that is catalyzed by a group of hydrolases called protein arginine deiminases (PADs). Hundreds of proteins are known to be citrullinated and hypercitrullination is associated with autoimmune diseases including rheumatoid arthritis (RA), lupus, ulcerative colitis (UC), Alzheimer's disease, multiple sclerosis (MS), and certain cancers. In this Account, we summarize our efforts to understand the structure and mechanism of the PADs and to develop small molecule chemical probes of protein citrullination. PAD activity is highly regulated by calcium. Structural studies with PAD2 revealed that calcium-binding occurs in a stepwise fashion and induces a series of dramatic conformational changes to form a catalytically competent active site. These studies also identified the presence of a calcium-switch that controls the overall calcium-dependence and a gatekeeper residue that shields the active site in the absence of calcium. Using biochemical and site-directed mutagenesis studies, we identified the key residues (two aspartates, a cysteine, and a histidine) responsible for catalysis and proposed a general mechanism of citrullination. Although all PADs follow this mechanism, substrate binding to the thiolate or thiol form of the enzyme varies for different isozymes. Substrate-specificity studies revealed that PADs 1-4 prefer peptidyl-arginine over free arginine and certain citrullination sites on a peptide substrate. Using high-throughput screening and activity-based protein profiling (ABPP), we identified several reversible (streptomycin, minocycline, and chlorotetracycline) and irreversible (streptonigrin, NSC 95397) PAD-inhibitors. Screening of a DNA-encoded library and lead-optimization led to the development of GSK199 and GSK484 as highly potent PAD4-selective inhibitors. Furthermore, use of an electrophilic, cysteine-targeted haloacetamidine warhead to mimic the guanidinium group in arginine afforded several mechanism-based pan-PAD-inhibitors including Cl-amidine and BB-Cl-amidine. These compounds are highly efficacious in various animal models, including those mimicking RA, UC, and lupus. Structure-activity relationships identified numerous covalent PAD-inhibitors with different bioavailability, in vivo stability, and isozyme-selectivity (PAD1-selective: D-Cl-amidine; PAD2-selective: compounds 16-20; PAD3-selective: Cl4-amidine; and PAD4-selective: TDFA). Finally, this Account describes the development of PAD-targeted and citrulline-specific chemical probes. While PAD-targeted probes were utilized for identifying off-targets and developing high-throughput inhibitor screening platforms, citrulline-specific probes enabled the proteomic identification of novel diagnostic biomarkers of hypercitrullination-related autoimmune diseases. 10.1021/acs.accounts.9b00024
    Melatonin in macrophage biology: Current understanding and future perspectives. Xia Yaoyao,Chen Siyuan,Zeng Sijing,Zhao Yuanyuan,Zhu Congrui,Deng Baichuan,Zhu Guoqiang,Yin Yulong,Wang Wence,Hardeland Rüdiger,Ren Wenkai Journal of pineal research Melatonin is a ubiquitous hormone found in various organisms and highly affects the function of immune cells. In this review, we summarize the current understanding of the significance of melatonin in macrophage biology and the beneficial effects of melatonin in macrophage-associated diseases. Enzymes associated with synthesis of melatonin, as well as membrane receptors for melatonin, are found in macrophages. Indeed, melatonin influences the phenotype polarization of macrophages. Mechanistically, the roles of melatonin in macrophages are related to several cellular signaling pathways, such as NF-κB, STATs, and NLRP3/caspase-1. Notably, miRNAs (eg, miR-155/-34a/-23a), cellular metabolic pathways (eg, α-KG, HIF-1α, and ROS), and mitochondrial dynamics and mitophagy are also involved. Thus, melatonin modulates the development and progression of various macrophage-associated diseases, such as cancer and rheumatoid arthritis. This review provides a better understanding about the importance of melatonin in macrophage biology and macrophage-associated diseases. 10.1111/jpi.12547
    Interferon target-gene expression and epigenomic signatures in health and disease. Barrat Franck J,Crow Mary K,Ivashkiv Lionel B Nature immunology Multiple type I interferons and interferon-γ (IFN-γ) are expressed under physiological conditions and are increased by stress and infections, and in autoinflammatory and autoimmune diseases. Interferons activate the Jak-STAT signaling pathway and induce overlapping patterns of expression, called 'interferon signatures', of canonical interferon-stimulated genes (ISGs) encoding molecules important for antiviral responses, antigen presentation, autoimmunity and inflammation. It has now become clear that interferons also induce an 'interferon epigenomic signature' by activating latent enhancers and 'bookmarking' chromatin, thus reprogramming cell responses to environmental cues. The interferon epigenomic signature affects ISGs and other gene sets, including canonical targets of the transcription factor NF-κB that encode inflammatory molecules, and is involved in the priming of immune cells, tolerance and the training of innate immune memory. Here we review the mechanisms through which interferon signatures and interferon epigenomic signatures are generated, as well as the expression and functional consequences of these signatures in homeostasis and autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis and systemic sclerosis. 10.1038/s41590-019-0466-2
    Lysosomes as a therapeutic target. Bonam Srinivasa Reddy,Wang Fengjuan,Muller Sylviane Nature reviews. Drug discovery Lysosomes are membrane-bound organelles with roles in processes involved in degrading and recycling cellular waste, cellular signalling and energy metabolism. Defects in genes encoding lysosomal proteins cause lysosomal storage disorders, in which enzyme replacement therapy has proved successful. Growing evidence also implicates roles for lysosomal dysfunction in more common diseases including inflammatory and autoimmune disorders, neurodegenerative diseases, cancer and metabolic disorders. With a focus on lysosomal dysfunction in autoimmune disorders and neurodegenerative diseases - including lupus, rheumatoid arthritis, multiple sclerosis, Alzheimer disease and Parkinson disease - this Review critically analyses progress and opportunities for therapeutically targeting lysosomal proteins and processes, particularly with small molecules and peptide drugs. 10.1038/s41573-019-0036-1
    FMS-like Tyrosine Kinase 3/FLT3: From Basic Science to Clinical Implications. Kazi Julhash U,Rönnstrand Lars Physiological reviews FMS-like tyrosine kinase 3 (FLT3) is a receptor tyrosine kinase that is expressed almost exclusively in the hematopoietic compartment. Its ligand, FLT3 ligand (FL), induces dimerization and activation of its intrinsic tyrosine kinase activity. Activation of FLT3 leads to its autophosphorylation and initiation of several signal transduction cascades. Signaling is initiated by the recruitment of signal transduction molecules to activated FLT3 through binding to specific phosphorylated tyrosine residues in the intracellular region of FLT3. Activation of FLT3 mediates cell survival, cell proliferation, and differentiation of hematopoietic progenitor cells. It acts in synergy with several other cytokines to promote its biological effects. Deregulated FLT3 activity has been implicated in several diseases, most prominently in acute myeloid leukemia where around one-third of patients carry an activating mutant of FLT3 which drives the disease and is correlated with poor prognosis. Overactivity of FLT3 has also been implicated in autoimmune diseases, such as rheumatoid arthritis. The observation that gain-of-function mutations of FLT3 can promote leukemogenesis has stimulated the development of inhibitors that target this receptor. Many of these are in clinical trials, and some have been approved for clinical use. However, problems with acquired resistance to these inhibitors are common and, furthermore, only a fraction of patients respond to these selective treatments. This review provides a summary of our current knowledge regarding structural and functional aspects of FLT3 signaling, both under normal and pathological conditions, and discusses challenges for the future regarding the use of targeted inhibition of these pathways for the treatment of patients. 10.1152/physrev.00029.2018
    Chemokines in rheumatic diseases: pathogenic role and therapeutic implications. Nature reviews. Rheumatology Chemokines, a family of small secreted chemotactic cytokines, and their G protein-coupled seven transmembrane spanning receptors control the migratory patterns, positioning and cellular interactions of immune cells. The levels of chemokines and their receptors are increased in the blood and within inflamed tissue of patients with rheumatic diseases, such as rheumatoid arthritis, systemic lupus erythematosus, systemic sclerosis, vasculitis or idiopathic inflammatory myopathies. Chemokine ligand-receptor interactions control the recruitment of leukocytes into tissue, which are central to the pathogenesis of these rheumatic diseases. Although the blockade of various chemokines and chemokine receptors has yielded promising results in preclinical animal models of rheumatic diseases, human clinical trials have, in general, been disappointing. However, there have been glimmers of hope from several early-phase clinical trials that suggest that sufficiently blocking the relevant chemokine pathway might in fact have clinical benefits in rheumatic diseases. Hence, the chemokine system remains a promising therapeutic target for rheumatic diseases and requires further study. 10.1038/s41584-019-0323-6
    The Purinergic System as a Pharmacological Target for the Treatment of Immune-Mediated Inflammatory Diseases. Antonioli Luca,Blandizzi Corrado,Pacher Pál,Haskó György Pharmacological reviews Immune-mediated inflammatory diseases (IMIDs) encompass a wide range of seemingly unrelated conditions, such as multiple sclerosis, rheumatoid arthritis, psoriasis, inflammatory bowel diseases, asthma, chronic obstructive pulmonary disease, and systemic lupus erythematosus. Despite differing etiologies, these diseases share common inflammatory pathways, which lead to damage in primary target organs and frequently to a plethora of systemic effects as well. The purinergic signaling complex comprising extracellular nucleotides and nucleosides and their receptors, the P2 and P1 purinergic receptors, respectively, as well as catabolic enzymes and nucleoside transporters is a major regulatory system in the body. The purinergic signaling complex can regulate the development and course of IMIDs. Here we provide a comprehensive review on the role of purinergic signaling in controlling immunity, inflammation, and organ function in IMIDs. In addition, we discuss the possible therapeutic applications of drugs acting on purinergic pathways, which have been entering clinical development, to manage patients suffering from IMIDs. 10.1124/pr.117.014878
    Fine tuning of immunometabolism for the treatment of rheumatic diseases. Rhoads Jillian P,Major Amy S,Rathmell Jeffrey C Nature reviews. Rheumatology All immune cells depend on specific and efficient metabolic pathways to mount an appropriate response. Over the past decade, the field of immunometabolism has expanded our understanding of the various means by which cells modulate metabolism to achieve the effector functions necessary to fight infection or maintain homeostasis. Harnessing these metabolic pathways to manipulate inappropriate immune responses as a therapeutic strategy in cancer and autoimmunity has received increasing scrutiny by the scientific community. Fine tuning immunometabolism to provide the desired response, or prevent a deleterious response, is an attractive alternative to chemotherapy or overt immunosuppression. The various metabolic pathways used by immune cells in rheumatoid arthritis, systemic lupus erythematosus and osteoarthritis offer numerous opportunities for selective targeting of specific immune cell subsets to manipulate cellular metabolism for therapeutic benefit in these rheumatologic diseases. 10.1038/nrrheum.2017.54
    Updating osteoimmunology: regulation of bone cells by innate and adaptive immunity. Walsh Matthew C,Takegahara Noriko,Kim Hyunsoo,Choi Yongwon Nature reviews. Rheumatology Osteoimmunology encompasses all aspects of the cross-regulation of bone and the immune system, including various cell types, signalling pathways, cytokines and chemokines, under both homeostatic and pathogenic conditions. A number of key areas are of increasing interest and relevance to osteoimmunology researchers. Although rheumatoid arthritis has long been recognized as one of the most common autoimmune diseases to affect bone integrity, researchers have focused increased attention on understanding how molecular triggers and innate signalling pathways (such as Toll-like receptors and purinergic signalling pathways) related to pathogenic and/or commensal microbiota are relevant to bone biology and rheumatic diseases. Additionally, although most discussions relating to osteoimmune regulation of homeostasis and disease have focused on the effects of adaptive immune responses on bone, evidence exists of the regulation of immune cells by bone cells, a concept that is consistent with the established role of the bone marrow in the development and homeostasis of the immune system. The active regulation of immune cells by bone cells is an interesting emerging component of investigations that seek to understand how to control immune-associated diseases of the bone and joints. 10.1038/nrrheum.2017.213
    JAK inhibition as a therapeutic strategy for immune and inflammatory diseases. Schwartz Daniella M,Kanno Yuka,Villarino Alejandro,Ward Michael,Gadina Massimo,O'Shea John J Nature reviews. Drug discovery The discovery of cytokines as key drivers of immune-mediated diseases has spurred efforts to target their associated signalling pathways. Janus kinases (JAKs) are essential signalling mediators downstream of many pro-inflammatory cytokines, and small-molecule inhibitors of JAKs (jakinibs) have gained traction as safe and efficacious options for the treatment of inflammation-driven pathologies such as rheumatoid arthritis, psoriasis and inflammatory bowel disease. Building on the clinical success of first-generation jakinibs, second-generation compounds that claim to be more selective are currently undergoing development and proceeding to clinical trials. However, important questions remain about the advantages and limitations of improved JAK selectivity, optimal routes and dosing regimens and how best to identify patients who will benefit from jakinibs. This Review discusses the biology of jakinibs from a translational perspective, focusing on recent insights from clinical trials, the development of novel agents and the use of jakinibs in a spectrum of immune and inflammatory diseases. 10.1038/nrd.2017.201
    The role of neutrophil extracellular traps in rheumatic diseases. Apel Falko,Zychlinsky Arturo,Kenny Elaine F Nature reviews. Rheumatology Rheumatic diseases are a collection of disorders defined by the presence of inflammation and destruction of joints and internal organs. A common feature of these diseases is the presence of autoantibodies targeting molecules commonly expressed in neutrophils. These preformed mediators are released by neutrophils but not by other immune cells such as macrophages. Neutrophils, major players in the host innate immune response, initiate a cell death mechanism termed neutrophil extracellular trap (NET) formation as a way to ensnare pathogens. NETs are also a source of released self-molecules found in rheumatic diseases. Subsequently, research on the role of NETs in the onset, progression and resolution of inflammation in rheumatic diseases has intensified. This Review has two aims. First, it aims to highlight the mechanisms required for the generation of NETs, the research landscape of which is rapidly changing. Second, it aims to discuss the role of neutrophils and NETs in systemic lupus erythematosus, vasculitis (specifically anti-neutrophil cytoplasmic autoantibody-associated vasculitis), rheumatoid arthritis and gout. Our goal is to clarify the field of NET research in rheumatic diseases in the hope of improving the therapeutic approaches utilized for these diseases. 10.1038/s41584-018-0039-z
    Beyond TNF: TNF superfamily cytokines as targets for the treatment of rheumatic diseases. Croft Michael,Siegel Richard M Nature reviews. Rheumatology TNF blockers are highly efficacious at dampening inflammation and reducing symptoms in rheumatic diseases such as rheumatoid arthritis, psoriatic arthritis and ankylosing spondylitis, and also in nonrheumatic syndromes such as inflammatory bowel disease. As TNF belongs to a superfamily of 19 structurally related proteins that have both proinflammatory and anti-inflammatory activity, reagents that disrupt the interaction between proinflammatory TNF family cytokines and their receptors, or agonize the anti-inflammatory receptors, are being considered for the treatment of rheumatic diseases. Biologic agents that block B cell activating factor (BAFF) and receptor activator of nuclear factor-κB ligand (RANKL) have been approved for the treatment of systemic lupus erythematosus and osteoporosis, respectively. In this Review, we focus on additional members of the TNF superfamily that could be relevant for the pathogenesis of rheumatic disease, including those that can strongly promote activity of immune cells or increase activity of tissue cells, as well as those that promote death pathways and might limit inflammation. We examine preclinical mouse and human data linking these molecules to the control of damage in the joints, muscle, bone or other tissues, and discuss their potential as targets for future therapy of rheumatic diseases. 10.1038/nrrheum.2017.22
    Engineered Sialylation of Pathogenic Antibodies In Vivo Attenuates Autoimmune Disease. Pagan Jose D,Kitaoka Maya,Anthony Robert M Cell Self-reactive IgGs contribute to the pathology of autoimmune diseases, including systemic lupus erythematosus and rheumatoid arthritis. Paradoxically, IgGs are used to treat inflammatory diseases in the form of high-dose intravenous immunoglobulin (IVIG). Distinct glycoforms on the IgG crystallizable fragment (Fc) dictate these divergent functions. IgG anti-inflammatory activity is attributed to sialylation of the Fc glycan. We therefore sought to convert endogenous IgG to anti-inflammatory mediators in vivo by engineering solubilized glycosyltransferases that attach galactose or sialic acid. When both enzymes were administered in a prophylactic or therapeutic fashion, autoimmune inflammation was markedly attenuated in vivo. The enzymes worked through a similar pathway to IVIG, requiring DC-SIGN, STAT6 signaling, and FcγRIIB. Importantly, sialylation was highly specific to pathogenic IgG at the site of inflammation, driven by local platelet release of nucleotide-sugar donors. These results underscore the therapeutic potential of glycoengineering in vivo. 10.1016/j.cell.2017.11.041
    The signaling adaptor TRAF1 negatively regulates Toll-like receptor signaling and this underlies its role in rheumatic disease. Abdul-Sater Ali A,Edilova Maria I,Clouthier Derek L,Mbanwi Achire,Kremmer Elisabeth,Watts Tania H Nature immunology TRAF1 is a signaling adaptor known for its role in tumor necrosis factor receptor-induced cell survival. Here we show that monocytes from healthy human subjects with a rheumatoid arthritis-associated single-nucleotide polymorphism (SNP) in the TRAF1 gene express less TRAF1 protein but greater amounts of inflammatory cytokines in response to lipopolysaccharide (LPS). The TRAF1 MATH domain binds directly to three components of the linear ubiquitination (LUBAC) complex, SHARPIN, HOIP and HOIL-1, to interfere with the recruitment and linear ubiquitination of NEMO. This results in decreased NF-κB activation and cytokine production, independently of tumor necrosis factor. Consistent with this, Traf1 mice show increased susceptibility to LPS-induced septic shock. These findings reveal an unexpected role for TRAF1 in negatively regulating Toll-like receptor signaling, providing a mechanistic explanation for the increased inflammation seen with a disease-associated TRAF1 SNP. 10.1038/ni.3618
    Management of chronic pain using complementary and integrative medicine. Chen Lucy,Michalsen Andreas BMJ (Clinical research ed.) Complementary and integrative medicine (CIM) encompasses both Western-style medicine and complementary health approaches as a new combined approach to treat a variety of clinical conditions. Chronic pain is the leading indication for use of CIM, and about 33% of adults and 12% of children in the US have used it in this context. Although advances have been made in treatments for chronic pain, it remains inadequately controlled for many people. Adverse effects and complications of analgesic drugs, such as addiction, kidney failure, and gastrointestinal bleeding, also limit their use. CIM offers a multimodality treatment approach that can tackle the multidimensional nature of pain with fewer or no serious adverse effects. This review focuses on the use of CIM in three conditions with a high incidence of chronic pain: back pain, neck pain, and rheumatoid arthritis. It summarizes research on the mechanisms of action and clinical studies on the efficacy of commonly used CIM modalities such as acupuncture, mind-body system, dietary interventions and fasting, and herbal medicine and nutrients. 10.1136/bmj.j1284
    Activation of naïve CD4 T cells re-tunes STAT1 signaling to deliver unique cytokine responses in memory CD4 T cells. Twohig Jason P,Cardus Figueras Ana,Andrews Robert,Wiede Florian,Cossins Benjamin C,Derrac Soria Alicia,Lewis Myles J,Townsend Michael J,Millrine David,Li Jasmine,Hill David G,Uceda Fernandez Javier,Liu Xiao,Szomolay Barbara,Pepper Christopher J,Taylor Philip R,Pitzalis Costantino,Tiganis Tony,Williams Nigel M,Jones Gareth W,Jones Simon A Nature immunology The cytokine IL-6 controls the survival, proliferation and effector characteristics of lymphocytes through activation of the transcription factors STAT1 and STAT3. While STAT3 activity is an ever-present feature of IL-6 signaling in CD4 T cells, prior activation via the T cell antigen receptor limits IL-6's control of STAT1 in effector and memory populations. Here we found that phosphorylation of STAT1 in response to IL-6 was regulated by the tyrosine phosphatases PTPN2 and PTPN22 expressed in response to the activation of naïve CD4 T cells. Transcriptomics and chromatin immunoprecipitation-sequencing (ChIP-seq) of IL-6 responses in naïve and effector memory CD4 T cells showed how the suppression of STAT1 activation shaped the functional identity and effector characteristics of memory CD4 T cells. Thus, tyrosine phosphatases induced by the activation of naïve T cells determine the way activated or memory CD4 T cells sense and interpret cytokine signals. 10.1038/s41590-019-0350-0
    Regulation of autoantibody activity by the IL-23-T17 axis determines the onset of autoimmune disease. Pfeifle René,Rothe Tobias,Ipseiz Natacha,Scherer Hans U,Culemann Stephan,Harre Ulrike,Ackermann Jochen A,Seefried Martina,Kleyer Arnd,Uderhardt Stefan,Haugg Benjamin,Hueber Axel J,Daum Patrick,Heidkamp Gordon F,Ge Changrong,Böhm Sybille,Lux Anja,Schuh Wolfgang,Magorivska Iryna,Nandakumar Kutty S,Lönnblom Erik,Becker Christoph,Dudziak Diana,Wuhrer Manfred,Rombouts Yoann,Koeleman Carolien A,Toes René,Winkler Thomas H,Holmdahl Rikard,Herrmann Martin,Blüml Stephan,Nimmerjahn Falk,Schett Georg,Krönke Gerhard Nature immunology The checkpoints and mechanisms that contribute to autoantibody-driven disease are as yet incompletely understood. Here we identified the axis of interleukin 23 (IL-23) and the T17 subset of helper T cells as a decisive factor that controlled the intrinsic inflammatory activity of autoantibodies and triggered the clinical onset of autoimmune arthritis. By instructing B cells in an IL-22- and IL-21-dependent manner, T17 cells regulated the expression of β-galactoside α2,6-sialyltransferase 1 in newly differentiating antibody-producing cells and determined the glycosylation profile and activity of immunoglobulin G (IgG) produced by the plasma cells that subsequently emerged. Asymptomatic humans with rheumatoid arthritis (RA)-specific autoantibodies showed identical changes in the activity and glycosylation of autoreactive IgG antibodies before shifting to the inflammatory phase of RA; thus, our results identify an IL-23-T17 cell-dependent pathway that controls autoantibody activity and unmasks a preexisting breach in immunotolerance. 10.1038/ni.3579
    Locally renewing resident synovial macrophages provide a protective barrier for the joint. Culemann Stephan,Grüneboom Anika,Nicolás-Ávila José Ángel,Weidner Daniela,Lämmle Katrin Franziska,Rothe Tobias,Quintana Juan A,Kirchner Philipp,Krljanac Branislav,Eberhardt Martin,Ferrazzi Fulvia,Kretzschmar Elke,Schicht Martin,Fischer Kim,Gelse Kolja,Faas Maria,Pfeifle René,Ackermann Jochen A,Pachowsky Milena,Renner Nina,Simon David,Haseloff Reiner F,Ekici Arif B,Bäuerle Tobias,Blasig Ingolf E,Vera Julio,Voehringer David,Kleyer Arnd,Paulsen Friedrich,Schett Georg,Hidalgo Andrés,Krönke Gerhard Nature Macrophages are considered to contribute to chronic inflammatory diseases such as rheumatoid arthritis. However, both the exact origin and the role of macrophages in inflammatory joint disease remain unclear. Here we use fate-mapping approaches in conjunction with three-dimensional light-sheet fluorescence microscopy and single-cell RNA sequencing to perform a comprehensive spatiotemporal analysis of the composition, origin and differentiation of subsets of macrophages within healthy and inflamed joints, and study the roles of these macrophages during arthritis. We find that dynamic membrane-like structures, consisting of a distinct population of CXCR1 tissue-resident macrophages, form an internal immunological barrier at the synovial lining and physically seclude the joint. These barrier-forming macrophages display features that are otherwise typical of epithelial cells, and maintain their numbers through a pool of locally proliferating CXCR1 mononuclear cells that are embedded into the synovial tissue. Unlike recruited monocyte-derived macrophages, which actively contribute to joint inflammation, these epithelial-like CXCR1 lining macrophages restrict the inflammatory reaction by providing a tight-junction-mediated shield for intra-articular structures. Our data reveal an unexpected functional diversification among synovial macrophages and have important implications for the general role of macrophages in health and disease. 10.1038/s41586-019-1471-1
    Structural Activation of Pro-inflammatory Human Cytokine IL-23 by Cognate IL-23 Receptor Enables Recruitment of the Shared Receptor IL-12Rβ1. Bloch Yehudi,Bouchareychas Laura,Merceron Romain,Składanowska Katarzyna,Van den Bossche Lien,Detry Sammy,Govindarajan Srinath,Elewaut Dirk,Haerynck Filomeen,Dullaers Melissa,Adamopoulos Iannis E,Savvides Savvas N Immunity Interleukin-23 (IL-23), an IL-12 family cytokine, plays pivotal roles in pro-inflammatory T helper 17 cell responses linked to autoimmune and inflammatory diseases. Despite intense therapeutic targeting, structural and mechanistic insights into receptor complexes mediated by IL-23, and by IL-12 family members in general, have remained elusive. We determined a crystal structure of human IL-23 in complex with its cognate receptor, IL-23R, and revealed that IL-23R bound to IL-23 exclusively via its N-terminal immunoglobulin domain. The structural and functional hotspot of this interaction partially restructured the helical IL-23p19 subunit of IL-23 and restrained its IL-12p40 subunit to cooperatively bind the shared receptor IL-12Rβ1 with high affinity. Together with structural insights from the interaction of IL-23 with the inhibitory antibody briakinumab and by leveraging additional IL-23:antibody complexes, we propose a mechanistic paradigm for IL-23 and IL-12 whereby cognate receptor binding to the helical cytokine subunits primes recruitment of the shared receptors via the IL-12p40 subunit. 10.1016/j.immuni.2017.12.008
    Mechanisms and Therapeutic Relevance of Neuro-immune Communication. Chavan Sangeeta S,Pavlov Valentin A,Tracey Kevin J Immunity Active research at the frontiers of immunology and neuroscience has identified multiple points of interaction and communication between the immune system and the nervous system. Immune cell activation stimulates neuronal circuits that regulate innate and adaptive immunity. Molecular mechanistic insights into the inflammatory reflex and other neuro-immune interactions have greatly advanced our understanding of immunity and identified new therapeutic possibilities in inflammatory and autoimmune diseases. Recent successful clinical trials using bioelectronic devices that modulate the inflammatory reflex to significantly ameliorate rheumatoid arthritis and inflammatory bowel disease provide a path for using electrons as a therapeutic modality for targeting molecular mechanisms of immunity. Here, we review mechanisms of peripheral sensory neuronal function in response to immune challenges, the neural regulation of immunity and inflammation, and the therapeutic implications of those mechanistic insights. 10.1016/j.immuni.2017.06.008
    Co-stimulatory and Co-inhibitory Pathways in Autoimmunity. Zhang Qianxia,Vignali Dario A A Immunity The immune system is guided by a series of checks and balances, a major component of which is a large array of co-stimulatory and co-inhibitory pathways that modulate the host response. Although co-stimulation is essential for boosting and shaping the initial response following signaling through the antigen receptor, inhibitory pathways are also critical for modulating the immune response. Excessive co-stimulation and/or insufficient co-inhibition can lead to a breakdown of self-tolerance and thus to autoimmunity. In this review, we will focus on the role of co-stimulatory and co-inhibitory pathways in two systemic (systemic lupus erythematosus and rheumatoid arthritis) and two organ-specific (multiple sclerosis and type 1 diabetes) emblematic autoimmune diseases. We will also discuss how mechanistic analysis of these pathways has led to the identification of potential therapeutic targets and initiation of clinical trials for autoimmune diseases, as well as outline some of the challenges that lie ahead. 10.1016/j.immuni.2016.04.017
    Osteoimmunology: The Conceptual Framework Unifying the Immune and Skeletal Systems. Okamoto Kazuo,Nakashima Tomoki,Shinohara Masahiro,Negishi-Koga Takako,Komatsu Noriko,Terashima Asuka,Sawa Shinichiro,Nitta Takeshi,Takayanagi Hiroshi Physiological reviews The immune and skeletal systems share a variety of molecules, including cytokines, chemokines, hormones, receptors, and transcription factors. Bone cells interact with immune cells under physiological and pathological conditions. Osteoimmunology was created as a new interdisciplinary field in large part to highlight the shared molecules and reciprocal interactions between the two systems in both heath and disease. Receptor activator of NF-κB ligand (RANKL) plays an essential role not only in the development of immune organs and bones, but also in autoimmune diseases affecting bone, thus effectively comprising the molecule that links the two systems. Here we review the function, gene regulation, and signal transduction of osteoimmune molecules, including RANKL, in the context of osteoclastogenesis as well as multiple other regulatory functions. Osteoimmunology has become indispensable for understanding the pathogenesis of a number of diseases such as rheumatoid arthritis (RA). We review the various osteoimmune pathologies, including the bone destruction in RA, in which pathogenic helper T cell subsets [such as IL-17-expressing helper T (Th17) cells] induce bone erosion through aberrant RANKL expression. We also focus on cellular interactions and the identification of the communication factors in the bone marrow, discussing the contribution of bone cells to the maintenance and regulation of hematopoietic stem and progenitors cells. Thus the time has come for a basic reappraisal of the framework for understanding both the immune and bone systems. The concept of a unified osteoimmune system will be absolutely indispensable for basic and translational approaches to diseases related to bone and/or the immune system. 10.1152/physrev.00036.2016
    The inflammatory role of phagocyte apoptotic pathways in rheumatic diseases. Cuda Carla M,Pope Richard M,Perlman Harris Nature reviews. Rheumatology Rheumatoid arthritis affects nearly 1% of the world's population and is a debilitating autoimmune condition that can result in joint destruction. During the past decade, inflammatory functions have been described for signalling molecules classically involved in apoptotic and non-apoptotic death pathways, including, but not limited to, Toll-like receptor signalling, inflammasome activation, cytokine production, macrophage polarization and antigen citrullination. In light of these remarkable advances in the understanding of inflammatory mechanisms of the death machinery, this Review provides a snapshot of the available evidence implicating death pathways, especially within the phagocyte populations of the innate immune system, in the perpetuation of rheumatoid arthritis and other rheumatic diseases. Elevated levels of signalling mediators of both extrinsic and intrinsic apoptosis, as well as the autophagy, are observed in the joints of patients with rheumatoid arthritis. Furthermore, risk polymorphisms are present in signalling molecules of the extrinsic apoptotic and autophagy death pathways. Although research into the mechanisms underlying these pathways has made considerable progress, this Review highlights areas where further investigation is particularly needed. This exploration is critical, as new discoveries in this field could lead to the development of novel therapies for rheumatoid arthritis and other rheumatic diseases. 10.1038/nrrheum.2016.132
    Targeting Interleukin-6 Signaling in Clinic. Kang Sujin,Tanaka Toshio,Narazaki Masashi,Kishimoto Tadamitsu Immunity Interleukin-6 (IL-6) is a pleiotropic cytokine with roles in immunity, tissue regeneration, and metabolism. Rapid production of IL-6 contributes to host defense during infection and tissue injury, but excessive synthesis of IL-6 and dysregulation of IL-6 receptor signaling is involved in disease pathology. Therapeutic agents targeting the IL-6 axis are effective in rheumatoid arthritis, and applications are being extended to other settings of acute and chronic inflammation. Recent studies reveal that selective blockade of different modes of IL-6 receptor signaling has different outcomes on disease pathology, suggesting novel strategies for therapeutic intervention. However, some inflammatory diseases do not seem to respond to IL-6 blockade. Here, we review the current state of IL-6-targeting approaches in the clinic and discuss how to apply the growing understanding of the immunobiology of IL-6 to clinical decisions. 10.1016/j.immuni.2019.03.026
    Leptin in the interplay of inflammation, metabolism and immune system disorders. Abella Vanessa,Scotece Morena,Conde Javier,Pino Jesús,Gonzalez-Gay Miguel Angel,Gómez-Reino Juan J,Mera Antonio,Lago Francisca,Gómez Rodolfo,Gualillo Oreste Nature reviews. Rheumatology Leptin is one of the most relevant factors secreted by adipose tissue and the forerunner of a class of molecules collectively called adipokines. Initially discovered in 1994, its crucial role as a central regulator in energy homeostasis has been largely described during the past 20 years. Once secreted into the circulation, leptin reaches the central and peripheral nervous systems and acts by binding and activating the long form of leptin receptor (LEPR), regulating appetite and food intake, bone mass, basal metabolism, reproductive function and insulin secretion, among other processes. Research on the regulation of different adipose tissues has provided important insights into the intricate network that links nutrition, metabolism and immune homeostasis. The neuroendocrine and immune systems communicate bi-directionally through common ligands and receptors during stress responses and inflammation, and control cellular immune responses in several pathological situations including immune-inflammatory rheumatic diseases. This Review discusses the latest findings regarding the role of leptin in the immune system and metabolism, with particular emphasis on its effect on autoimmune and/or inflammatory rheumatic diseases, such as rheumatoid arthritis and osteoarthritis. 10.1038/nrrheum.2016.209
    Hypoxia-Sensitive COMMD1 Integrates Signaling and Cellular Metabolism in Human Macrophages and Suppresses Osteoclastogenesis. Murata Koichi,Fang Celestia,Terao Chikashi,Giannopoulou Eugenia G,Lee Ye Ji,Lee Min Joon,Mun Se-Hwan,Bae Seyeon,Qiao Yu,Yuan Ruoxi,Furu Moritoshi,Ito Hiromu,Ohmura Koichiro,Matsuda Shuichi,Mimori Tsuneyo,Matsuda Fumihiko,Park-Min Kyung-Hyun,Ivashkiv Lionel B Immunity Hypoxia augments inflammatory responses and osteoclastogenesis by incompletely understood mechanisms. We identified COMMD1 as a cell-intrinsic negative regulator of osteoclastogenesis that is suppressed by hypoxia. In human macrophages, COMMD1 restrained induction of NF-κB signaling and a transcription factor E2F1-dependent metabolic pathway by the cytokine RANKL. Downregulation of COMMD1 protein expression by hypoxia augmented RANKL-induced expression of inflammatory and E2F1 target genes and downstream osteoclastogenesis. E2F1 targets included glycolysis and metabolic genes including CKB that enabled cells to meet metabolic demands in challenging environments, as well as inflammatory cytokine-driven target genes. Expression quantitative trait locus analysis linked increased COMMD1 expression with decreased bone erosion in rheumatoid arthritis. Myeloid deletion of Commd1 resulted in increased osteoclastogenesis in arthritis and inflammatory osteolysis models. These results identify COMMD1 and an E2F-metabolic pathway as key regulators of osteoclastogenic responses under pathological inflammatory conditions and provide a mechanism by which hypoxia augments inflammation and bone destruction. 10.1016/j.immuni.2017.06.018
    The complement system as a potential therapeutic target in rheumatic disease. Trouw Leendert A,Pickering Matthew C,Blom Anna M Nature reviews. Rheumatology Complement activation is associated with common rheumatic diseases such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA) and systemic vasculitis. Evidence linking complement activation to these diseases includes the presence of complement deposition in affected tissues, decreased levels of complement proteins and high levels of complement activation fragments in the blood and/or synovial fluid of patients with these diseases, as well as data from experimental models. Eculizumab, a monoclonal antibody that inhibits the complement component C5, is now approved for the treatment of rare conditions involving complement hyperactivation, and the success of this therapy has renewed interest in understanding the utility of complement inhibition in rheumatological practice, particularly for SLE. For example, inhibiting C5 is a potential means of reducing glomerular inflammation in lupus nephritis or treating thrombotic microangiopathy in SLE. The complement system is one of multiple mediators of tissue injury in complex diseases such as SLE, and identifying the disease context in which complement activation has a predominant role is a challenge. An added difficulty in RA is identifying a role for therapeutic complement inhibition within the diverse treatment modalities already available. In this Review, evidence for the therapeutic potential of complement manipulation in rheumatology practice is evaluated. 10.1038/nrrheum.2017.125
    Sclerostin inhibition promotes TNF-dependent inflammatory joint destruction. Wehmeyer Corinna,Frank Svetlana,Beckmann Denise,Böttcher Martin,Cromme Christoph,König Ulrich,Fennen Michelle,Held Annelena,Paruzel Peter,Hartmann Christine,Stratis Athanasios,Korb-Pap Adelheid,Kamradt Thomas,Kramer Ina,van den Berg Wim,Kneissel Michaela,Pap Thomas,Dankbar Berno Science translational medicine Sclerostin, an inhibitor of the Wnt/β-catenin pathway, has anti-anabolic effects on bone formation by negatively regulating osteoblast differentiation. Mutations in the human sclerostin gene (SOST) lead to sclerosteosis with progressive skeletal overgrowth, whereas sclerostin-deficient (Sost(-/-)) mice exhibit increased bone mass and strength. Therefore, antibody-mediated inhibition of sclerostin is currently being clinically evaluated for the treatment of postmenopausal osteoporosis in humans. We report that in chronic TNFα (tumor necrosis factor α)-dependent arthritis, fibroblast-like synoviocytes constitute a major source of sclerostin and that either the lack of sclerostin or its antibody-mediated inhibition leads to an acceleration of rheumatoid arthritis (RA)-like disease in human TNFα transgenic (hTNFtg) mice with enhanced pannus formation and joint destruction. Inhibition of sclerostin also failed to improve clinical signs and joint destruction in the partially TNFα-dependent glucose-6-phosphate isomerase-induced arthritis mouse model, but ameliorated disease severity in K/BxN serum transfer-induced arthritis mouse model, which is independent of TNF receptor signaling, thus suggesting a specific role for sclerostin in TNFα signaling. Sclerostin effectively blocked TNFα- but not interleukin-1-induced activation of p38, a key step in arthritis development, pointing to a previously unrealized protective role of sclerostin in TNF-mediated chronic inflammation. The possibility of anti-sclerostin antibody treatment worsening clinical RA outcome under chronic TNFα-dependent inflammatory conditions in mice means that caution should be taken both when considering such treatment for inflammatory bone loss in RA and when using anti-sclerostin antibodies in patients with TNFα-dependent comorbidities. 10.1126/scitranslmed.aac4351
    Interleukin-6: designing specific therapeutics for a complex cytokine. Garbers Christoph,Heink Sylvia,Korn Thomas,Rose-John Stefan Nature reviews. Drug discovery Interleukin-6 (IL-6) is a pivotal cytokine with a diverse repertoire of physiological functions that include regulation of immune cell proliferation and differentiation. Dysregulation of IL-6 signalling is associated with inflammatory and lymphoproliferative disorders such as rheumatoid arthritis and Castleman disease, and several classes of therapeutics have been developed that target components of the IL-6 signalling pathway. So far, monoclonal antibodies against IL-6 or IL-6 receptor (IL-6R) and Janus kinases (JAK) inhibitors have been successfully developed for the treatment of autoimmune diseases such as rheumatoid arthritis. However, clinical trials of agents targeting IL-6 signalling have also raised questions about the diseases and patient populations for which such agents have an appropriate benefit-risk profile. Knowledge from clinical trials and advances in our understanding of the complexities of IL-6 signalling, including the potential to target an IL-6 trans-signalling pathway, are now indicating novel opportunities for therapeutic intervention. In this Review, we overview the roles of IL-6 in health and disease and analyse progress with several approaches of inhibiting IL-6-signalling, with the aim of illuminating when and how to apply IL-6 blockade. 10.1038/nrd.2018.45
    Segmented Filamentous Bacteria Provoke Lung Autoimmunity by Inducing Gut-Lung Axis Th17 Cells Expressing Dual TCRs. Bradley C Pierce,Teng Fei,Felix Krysta M,Sano Teruyuki,Naskar Debdut,Block Katharine E,Huang Haochu,Knox Kenneth S,Littman Dan R,Wu Hsin-Jung Joyce Cell host & microbe Lung complications are a major cause of rheumatoid arthritis-related mortality. Involvement of gut microbiota in lung diseases by the gut-lung axis has been widely observed, but the underlying mechanism remains mostly unknown. Using an autoimmune arthritis model, we show that a constituent of the gut microbiota, segmented filamentous bacteria (SFB), distantly provoke lung pathology. SFB induce autoantibodies in lung during the pre-arthritic phase, and SFB-dependent lung pathology requires the T helper 17 (Th17) responses. SFB-induced gut Th17 cells are preferentially recruited to lung over spleen due to robust expression in the lung of the Th17 chemoattractant, CCL20. Additionally, we found that in peripheral tissues, SFB selectively expand dual T cell receptor (TCR)-expressing Th17 cells recognizing both an SFB epitope and self-antigen, thus augmenting autoimmunity. This study reveals mechanisms for commensal-mediated gut-lung crosstalk and dual TCR-based autoimmunity. 10.1016/j.chom.2017.10.007
    Distinct fibroblast subsets drive inflammation and damage in arthritis. Croft Adam P,Campos Joana,Jansen Kathrin,Turner Jason D,Marshall Jennifer,Attar Moustafa,Savary Loriane,Wehmeyer Corinna,Naylor Amy J,Kemble Samuel,Begum Jenefa,Dürholz Kerstin,Perlman Harris,Barone Francesca,McGettrick Helen M,Fearon Douglas T,Wei Kevin,Raychaudhuri Soumya,Korsunsky Ilya,Brenner Michael B,Coles Mark,Sansom Stephen N,Filer Andrew,Buckley Christopher D Nature The identification of lymphocyte subsets with non-overlapping effector functions has been pivotal to the development of targeted therapies in immune-mediated inflammatory diseases (IMIDs). However, it remains unclear whether fibroblast subclasses with non-overlapping functions also exist and are responsible for the wide variety of tissue-driven processes observed in IMIDs, such as inflammation and damage. Here we identify and describe the biology of distinct subsets of fibroblasts responsible for mediating either inflammation or tissue damage in arthritis. We show that deletion of fibroblast activation protein-α (FAPα) fibroblasts suppressed both inflammation and bone erosions in mouse models of resolving and persistent arthritis. Single-cell transcriptional analysis identified two distinct fibroblast subsets within the FAPα population: FAPαTHY1 immune effector fibroblasts located in the synovial sub-lining, and FAPαTHY1 destructive fibroblasts restricted to the synovial lining layer. When adoptively transferred into the joint, FAPαTHY1 fibroblasts selectively mediate bone and cartilage damage with little effect on inflammation, whereas transfer of FAPα THY1 fibroblasts resulted in a more severe and persistent inflammatory arthritis, with minimal effect on bone and cartilage. Our findings describing anatomically discrete, functionally distinct fibroblast subsets with non-overlapping functions have important implications for cell-based therapies aimed at modulating inflammation and tissue damage. 10.1038/s41586-019-1263-7
    Identification of a novel arthritis-associated osteoclast precursor macrophage regulated by FoxM1. Hasegawa Tetsuo,Kikuta Junichi,Sudo Takao,Matsuura Yoshinobu,Matsui Takahiro,Simmons Szandor,Ebina Kosuke,Hirao Makoto,Okuzaki Daisuke,Yoshida Yuichi,Hirao Atsushi,Kalinichenko Vladimir V,Yamaoka Kunihiro,Takeuchi Tsutomu,Ishii Masaru Nature immunology Osteoclasts have a unique bone-destroying capacity, playing key roles in steady-state bone remodeling and arthritic bone erosion. Whether the osteoclasts in these different tissue settings arise from the same precursor states of monocytoid cells is presently unknown. Here, we show that osteoclasts in pannus originate exclusively from circulating bone marrow-derived cells and not from locally resident macrophages. We identify murine CXCR1Ly6CF4/80I-A/I-E macrophages (termed here arthritis-associated osteoclastogenic macrophages (AtoMs)) as the osteoclast precursor-containing population in the inflamed synovium, comprising a subset distinct from conventional osteoclast precursors in homeostatic bone remodeling. Tamoxifen-inducible Foxm1 deletion suppressed the capacity of AtoMs to differentiate into osteoclasts in vitro and in vivo. Furthermore, synovial samples from human patients with rheumatoid arthritis contained CXCR1HLA-DRCD11cCD80CD86 cells that corresponded to mouse AtoMs, and human osteoclastogenesis was inhibited by the FoxM1 inhibitor thiostrepton, constituting a potential target for rheumatoid arthritis treatment. 10.1038/s41590-019-0526-7
    Autoimmune Th17 Cells Induced Synovial Stromal and Innate Lymphoid Cell Secretion of the Cytokine GM-CSF to Initiate and Augment Autoimmune Arthritis. Hirota Keiji,Hashimoto Motomu,Ito Yoshinaga,Matsuura Mayumi,Ito Hiromu,Tanaka Masao,Watanabe Hitomi,Kondoh Gen,Tanaka Atsushi,Yasuda Keiko,Kopf Manfred,Potocnik Alexandre J,Stockinger Brigitta,Sakaguchi Noriko,Sakaguchi Shimon Immunity Despite the importance of Th17 cells in autoimmune diseases, it remains unclear how they control other inflammatory cells in autoimmune tissue damage. Using a model of spontaneous autoimmune arthritis, we showed that arthritogenic Th17 cells stimulated fibroblast-like synoviocytes via interleukin-17 (IL-17) to secrete the cytokine GM-CSF and also expanded synovial-resident innate lymphoid cells (ILCs) in inflamed joints. Activated synovial ILCs, which expressed CD25, IL-33Ra, and TLR9, produced abundant GM-CSF upon stimulation by IL-2, IL-33, or CpG DNA. Loss of GM-CSF production by either ILCs or radio-resistant stromal cells prevented Th17 cell-mediated arthritis. GM-CSF production by Th17 cells augmented chronic inflammation but was dispensable for the initiation of arthritis. We showed that GM-CSF-producing ILCs were present in inflamed joints of rheumatoid arthritis patients. Thus, a cellular cascade of autoimmune Th17 cells, ILCs, and stromal cells, via IL-17 and GM-CSF, mediates chronic joint inflammation and can be a target for therapeutic intervention. 10.1016/j.immuni.2018.04.009
    A noncanonical role for the engulfment gene ELMO1 in neutrophils that promotes inflammatory arthritis. Arandjelovic Sanja,Perry Justin S A,Lucas Christopher D,Penberthy Kristen K,Kim Tae-Hyoun,Zhou Ming,Rosen Dorian A,Chuang Tzu-Ying,Bettina Alexandra M,Shankman Laura S,Cohen Amanda H,Gaultier Alban,Conrads Thomas P,Kim Minsoo,Elliott Michael R,Ravichandran Kodi S Nature immunology Rheumatoid arthritis is characterized by progressive joint inflammation and affects ~1% of the human population. We noted single-nucleotide polymorphisms (SNPs) in the apoptotic cell-engulfment genes ELMO1, DOCK2, and RAC1 linked to rheumatoid arthritis. As ELMO1 promotes cytoskeletal reorganization during engulfment, we hypothesized that ELMO1 loss would worsen inflammatory arthritis. Surprisingly, Elmo1-deficient mice showed reduced joint inflammation in acute and chronic arthritis models. Genetic and cell-biology studies revealed that ELMO1 associates with receptors linked to neutrophil function in arthritis and regulates activation and early neutrophil recruitment to the joints, without general inhibition of inflammatory responses. Further, neutrophils from the peripheral blood of human donors that carry the SNP in ELMO1 associated with arthritis display increased migratory capacity, whereas ELMO1 knockdown reduces human neutrophil migration to chemokines linked to arthritis. These data identify 'noncanonical' roles for ELMO1 as an important cytoplasmic regulator of specific neutrophil receptors and promoter of arthritis. 10.1038/s41590-018-0293-x
    Deficient Activity of the Nuclease MRE11A Induces T Cell Aging and Promotes Arthritogenic Effector Functions in Patients with Rheumatoid Arthritis. Li Yinyin,Shen Yi,Hohensinner Philipp,Ju Jihang,Wen Zhenke,Goodman Stuart B,Zhang Hui,Goronzy Jörg J,Weyand Cornelia M Immunity Immune aging manifests with a combination of failing adaptive immunity and insufficiently restrained inflammation. In patients with rheumatoid arthritis (RA), T cell aging occurs prematurely, but the mechanisms involved and their contribution to tissue-destructive inflammation remain unclear. We found that RA CD4 T cells showed signs of aging during their primary immune responses and differentiated into tissue-invasive, proinflammatory effector cells. RA T cells had low expression of the double-strand-break repair nuclease MRE11A, leading to telomeric damage, juxtacentromeric heterochromatin unraveling, and senescence marker upregulation. Inhibition of MRE11A activity in healthy T cells induced the aging phenotype, whereas MRE11A overexpression in RA T cells reversed it. In human-synovium chimeric mice, MRE11A T cells were tissue-invasive and pro-arthritogenic, and MRE11A reconstitution mitigated synovitis. Our findings link premature T cell aging and tissue-invasiveness to telomere deprotection and heterochromatin unpacking, identifying MRE11A as a therapeutic target to combat immune aging and suppress dysregulated tissue inflammation. 10.1016/j.immuni.2016.09.013
    Macrophages take rheumatoid arthritis up a "Notch". Levi Benjamin Science translational medicine Notch signaling in bone marrow-derived inflammatory macrophages is central to synovial inflammation seen in rheumatoid arthritis, representing a promising future therapeutic target. 10.1126/scitranslmed.aan3022
    Successes and failures of chemokine-pathway targeting in rheumatoid arthritis. Szekanecz Zoltán,Koch Alisa E Nature reviews. Rheumatology Chemokines and chemokine receptors are involved in leukocyte recruitment and angiogenesis underlying the pathogenesis of rheumatoid arthritis (RA) and other inflammatory rheumatic diseases. Numerous chemokines, along with both conventional and atypical cell-surface chemokine receptors, are found in inflamed synovia. Preclinical studies carried out in animal models of arthritis involving agents targeting chemokines and chemokine receptors have yielded promising results. However, most human trials of treatment of RA with antibodies and synthetic compounds targeting chemokine signalling have failed to show clinical improvements. Chemokines can have overlapping actions, and their activities can be altered by chemical modification or proteolytic degradation. Effective targeting of chemokine pathways must take acount of these properties, and can also require high levels of receptor occupancy by therapeutic agents to prevent signalling. CCR1 is a promising target for chemokine-receptor blockade. 10.1038/nrrheum.2015.157
    Macrophage heterogeneity in the context of rheumatoid arthritis. Udalova Irina A,Mantovani Alberto,Feldmann Marc Nature reviews. Rheumatology Macrophages are very important in the pathogenesis of rheumatoid arthritis (RA). The increase in the number of sublining macrophages in the synovium is an early hallmark of active rheumatic disease, and high numbers of macrophages are a prominent feature of inflammatory lesions. The degree of synovial macrophage infiltration correlates with the degree of joint erosion, and depletion of these macrophages from inflamed tissue has a profound therapeutic benefit. Research has now uncovered an unexpectedly high level of heterogeneity in macrophage origin and function, and has emphasized the role of environmental factors in their functional specialization. Although the heterogeneous populations of macrophages in RA have not been fully characterized, preliminary results in mouse models of arthritis have contributed to our understanding of the phenotype and ontogeny of synovial macrophages, and to deciphering the properties of monocyte-derived infiltrating and tissue-resident macrophages. Elucidating the molecular mechanisms that drive polarization of macrophages towards proinflammatory or anti-inflammatory phenotypes could lead to identification of signalling pathways that inform future therapeutic strategies. 10.1038/nrrheum.2016.91
    Platelets: emerging facilitators of cellular crosstalk in rheumatoid arthritis. Olumuyiwa-Akeredolu Oore-Ofe,Page Martin J,Soma Prashilla,Pretorius Etheresia Nature reviews. Rheumatology Rheumatoid arthritis (RA) is an autoimmune disease in which a variety of circulating pro-inflammatory cells and dysregulated molecules are involved in disease aetiology and progression. Platelets are an important cellular element in the circulation that can bind several dysregulated molecules (such as collagen, thrombin and fibrinogen) that are present both in the synovium and the circulation of patients with RA. Platelets not only respond to dysregulated molecules in their environment but also transport and express their own inflammatory mediators, and serve as regulators at the boundary between haemostasis and immunity. Activated platelets also produce microparticles, which further convey signalling molecules and receptors to the synovium and circulation, thereby positioning these platelet-derived particles as strategic regulators of inflammation. These diverse functions come together to make platelets facilitators of cellular crosstalk in RA. Thus, the receptor functions, ligand binding potential and dysregulated signalling pathways in platelets are becoming increasingly important for treatment in RA. This Review aims to highlight the role of platelets in RA and the need to closely examine platelets as health indicators when designing effective pharmaceutical targets in this disease. 10.1038/s41584-019-0187-9
    Defining inflammatory cell states in rheumatoid arthritis joint synovial tissues by integrating single-cell transcriptomics and mass cytometry. Zhang Fan,Wei Kevin,Slowikowski Kamil,Fonseka Chamith Y,Rao Deepak A,Kelly Stephen,Goodman Susan M,Tabechian Darren,Hughes Laura B,Salomon-Escoto Karen,Watts Gerald F M,Jonsson A Helena,Rangel-Moreno Javier,Meednu Nida,Rozo Cristina,Apruzzese William,Eisenhaure Thomas M,Lieb David J,Boyle David L,Mandelin Arthur M, ,Boyce Brendan F,DiCarlo Edward,Gravallese Ellen M,Gregersen Peter K,Moreland Larry,Firestein Gary S,Hacohen Nir,Nusbaum Chad,Lederer James A,Perlman Harris,Pitzalis Costantino,Filer Andrew,Holers V Michael,Bykerk Vivian P,Donlin Laura T,Anolik Jennifer H,Brenner Michael B,Raychaudhuri Soumya Nature immunology To define the cell populations that drive joint inflammation in rheumatoid arthritis (RA), we applied single-cell RNA sequencing (scRNA-seq), mass cytometry, bulk RNA sequencing (RNA-seq) and flow cytometry to T cells, B cells, monocytes, and fibroblasts from 51 samples of synovial tissue from patients with RA or osteoarthritis (OA). Utilizing an integrated strategy based on canonical correlation analysis of 5,265 scRNA-seq profiles, we identified 18 unique cell populations. Combining mass cytometry and transcriptomics revealed cell states expanded in RA synovia: THY1(CD90)HLA-DRA sublining fibroblasts, IL1B pro-inflammatory monocytes, ITGAXTBX21 autoimmune-associated B cells and PDCD1 peripheral helper T (T) cells and follicular helper T (T) cells. We defined distinct subsets of CD8 T cells characterized by GZMK, GZMB, and GNLY phenotypes. We mapped inflammatory mediators to their source cell populations; for example, we attributed IL6 expression to THY1HLA-DRA fibroblasts and IL1B production to pro-inflammatory monocytes. These populations are potentially key mediators of RA pathogenesis. 10.1038/s41590-019-0378-1
    Inflammasomes contributing to inflammation in arthritis. Spel Lotte,Martinon Fabio Immunological reviews Inflammasomes are intracellular multiprotein signaling platforms that initiate inflammatory responses in response to pathogens and cellular damage. Active inflammasomes induce the enzymatic activity of caspase-1, resulting in the induction of inflammatory cell death, pyroptosis, and the maturation and secretion of inflammatory cytokines IL-1β and IL-18. Inflammasomes are activated in many inflammatory diseases, including autoinflammatory disorders and arthritis, and inflammasome-specific therapies are under development for the treatment of inflammatory conditions. In this review, we outline the different inflammasome platforms and recent findings contributing to our knowledge about inflammasome biology in health and disease. In particular, we discuss the role of the inflammasome in the pathogenesis of arthritic diseases, including rheumatoid arthritis, gout, ankylosing spondylitis, and juvenile idiopathic arthritis, and the potential of newly developed therapies that specifically target the inflammasome or its products for the treatment of inflammatory diseases. 10.1111/imr.12839
    B cells inhibit bone formation in rheumatoid arthritis by suppressing osteoblast differentiation. Sun Wen,Meednu Nida,Rosenberg Alexander,Rangel-Moreno Javier,Wang Victor,Glanzman Jason,Owen Teresa,Zhou Xichao,Zhang Hengwei,Boyce Brendan F,Anolik Jennifer H,Xing Lianping Nature communications The function of B cells in osteoblast (OB) dysfunction in rheumatoid arthritis (RA) has not been well-studied. Here we show that B cells are enriched in the subchondral and endosteal bone marrow (BM) areas adjacent to osteocalcin OBs in two murine RA models: collagen-induced arthritis and the TNF-transgenic mice. Subchondral BM B cells in RA mice express high levels of OB inhibitors, CCL3 and TNF, and inhibit OB differentiation by activating ERK and NF-κB signaling pathways. The inhibitory effect of RA B cells on OB differentiation is blocked by CCL3 and TNF neutralization, and deletion of CCL3 and TNF in RA B cells completely rescues OB function in vivo, while B cell depletion attenuates bone erosion and OB inhibition in RA mice. Lastly, B cells from RA patients express CCL3 and TNF and inhibit OB differentiation, with these effects ameliorated by CCL3 and TNF neutralization. Thus, B cells inhibit bone formation in RA by producing multiple OB inhibitors. 10.1038/s41467-018-07626-8
    EULAR recommendations for the management of rheumatoid arthritis with synthetic and biological disease-modifying antirheumatic drugs: 2019 update. Smolen Josef S,Landewé Robert B M,Bijlsma Johannes W J,Burmester Gerd R,Dougados Maxime,Kerschbaumer Andreas,McInnes Iain B,Sepriano Alexandre,van Vollenhoven Ronald F,de Wit Maarten,Aletaha Daniel,Aringer Martin,Askling John,Balsa Alejandro,Boers Maarten,den Broeder Alfons A,Buch Maya H,Buttgereit Frank,Caporali Roberto,Cardiel Mario Humberto,De Cock Diederik,Codreanu Catalin,Cutolo Maurizio,Edwards Christopher John,van Eijk-Hustings Yvonne,Emery Paul,Finckh Axel,Gossec Laure,Gottenberg Jacques-Eric,Hetland Merete Lund,Huizinga Tom W J,Koloumas Marios,Li Zhanguo,Mariette Xavier,Müller-Ladner Ulf,Mysler Eduardo F,da Silva Jose A P,Poór Gyula,Pope Janet E,Rubbert-Roth Andrea,Ruyssen-Witrand Adeline,Saag Kenneth G,Strangfeld Anja,Takeuchi Tsutomu,Voshaar Marieke,Westhovens René,van der Heijde Désirée Annals of the rheumatic diseases OBJECTIVES:To provide an update of the European League Against Rheumatism (EULAR) rheumatoid arthritis (RA) management recommendations to account for the most recent developments in the field. METHODS:An international task force considered new evidence supporting or contradicting previous recommendations and novel therapies and strategic insights based on two systematic literature searches on efficacy and safety of disease-modifying antirheumatic drugs (DMARDs) since the last update (2016) until 2019. A predefined voting process was applied, current levels of evidence and strengths of recommendation were assigned and participants ultimately voted independently on their level of agreement with each of the items. RESULTS:The task force agreed on 5 overarching principles and 12 recommendations concerning use of conventional synthetic (cs) DMARDs (methotrexate (MTX), leflunomide, sulfasalazine); glucocorticoids (GCs); biological (b) DMARDs (tumour necrosis factor inhibitors (adalimumab, certolizumab pegol, etanercept, golimumab, infliximab), abatacept, rituximab, tocilizumab, sarilumab and biosimilar (bs) DMARDs) and targeted synthetic (ts) DMARDs (the Janus kinase (JAK) inhibitors tofacitinib, baricitinib, filgotinib, upadacitinib). Guidance on monotherapy, combination therapy, treatment strategies (treat-to-target) and tapering on sustained clinical remission is provided. Cost and sequencing of b/tsDMARDs are addressed. Initially, MTX plus GCs and upon insufficient response to this therapy within 3 to 6 months, stratification according to risk factors is recommended. With poor prognostic factors (presence of autoantibodies, high disease activity, early erosions or failure of two csDMARDs), any bDMARD or JAK inhibitor should be added to the csDMARD. If this fails, any other bDMARD (from another or the same class) or tsDMARD is recommended. On sustained remission, DMARDs may be tapered, but not be stopped. Levels of evidence and levels of agreement were mostly high. CONCLUSIONS:These updated EULAR recommendations provide consensus on the management of RA with respect to benefit, safety, preferences and cost. 10.1136/annrheumdis-2019-216655
    Genetic variants shape rheumatoid arthritis-specific transcriptomic features in CD4 T cells through differential DNA methylation, explaining a substantial proportion of heritability. Ha Eunji,Bang So-Young,Lim Jiwoo,Yun Jun Ho,Kim Jeong-Min,Bae Jae-Bum,Lee Hye-Soon,Kim Bong-Jo,Kim Kwangwoo,Bae Sang-Cheol Annals of the rheumatic diseases OBJECTIVE:CD4 T cells have been suggested as the most disease-relevant cell type in rheumatoid arthritis (RA) in which RA-risk non-coding variants exhibit allele-specific effects on regulation of RA-driving genes. This study aimed to understand RA-specific signatures in CD4 T cells using multi-omics data, interpreting inter-omics relationships in shaping the RA transcriptomic landscape. METHODS:We profiled genome-wide variants, gene expression and DNA methylation in CD4 T cells from 82 patients with RA and 40 healthy controls using high-throughput technologies. We investigated differentially expressed genes (DEGs) and differential methylated regions (DMRs) in RA and localised quantitative trait loci (QTLs) for expression and methylation. We then integrated these based on individual-level correlations to inspect DEG-regulating sources and investigated the potential regulatory roles of RA-risk variants by a partitioned-heritability enrichment analysis with RA genome-wide association summary statistics. RESULTS:A large number of RA-specific DEGs were identified (n=2575), highlighting T cell differentiation and activation pathways. RA-specific DMRs, preferentially located in T cell regulatory regions, were correlated with the expression levels of 548 DEGs mostly in the same topologically associating domains. In addition, expressional variances in 771 and 83 DEGs were partially explained by expression QTLs for DEGs and methylation QTLs (meQTLs) for DEG-correlated DMRs, respectively. A large number of RA variants were moderately to strongly correlated with meQTLs. DEG-correlated DMRs, enriched with meQTLs, had strongly enriched heritability of RA. CONCLUSION:Our findings revealed that the methylomic changes, driven by RA heritability-explaining variants, shape the differential expression of a substantial fraction of DEGs in CD4 T cells in patients with RA, reinforcing the importance of a multidimensional approach in disease-relevant tissues. 10.1136/annrheumdis-2020-219152
    Endophilin A2 deficiency protects rodents from autoimmune arthritis by modulating T cell activation. Norin Ulrika,Rintisch Carola,Meng Liesu,Forster Florian,Ekman Diana,Tuncel Jonatan,Klocke Katrin,Bäcklund Johan,Yang Min,Bonner Michael Y,Lahore Gonzalo Fernandez,James Jaime,Shchetynsky Klementy,Bergquist Maria,Gjertsson Inger,Hubner Norbert,Bäckdahl Liselotte,Holmdahl Rikard Nature communications The introduction of the CTLA-4 recombinant fusion protein has demonstrated therapeutic effects by selectively modulating T-cell activation in rheumatoid arthritis. Here we show, using a forward genetic approach, that a mutation in the SH3gl1 gene encoding the endocytic protein Endophilin A2 is associated with the development of arthritis in rodents. Defective expression of SH3gl1 affects T cell effector functions and alters the activation threshold of autoreactive T cells, thereby leading to complete protection from chronic autoimmune inflammatory disease in both mice and rats. We further show that SH3GL1 regulates human T cell signaling and T cell receptor internalization, and its expression is upregulated in rheumatoid arthritis patients. Collectively our data identify SH3GL1 as a key regulator of T cell activation, and as a potential target for treatment of autoimmune diseases. 10.1038/s41467-020-20586-2
    Combination of human umbilical cord mesenchymal stem (stromal) cell transplantation with IFN-γ treatment synergistically improves the clinical outcomes of patients with rheumatoid arthritis. He Xiao,Yang Yi,Yao Mengwei,Yang Lei,Ao Luoquan,Hu Xueting,Li Zhan,Wu Xiaofeng,Tan Yan,Xing Wei,Guo Wei,Bellanti Joseph A,Zheng Song Guo,Xu Xiang Annals of the rheumatic diseases OBJECTIVES:To clarify the key role of circulating interferon-γ (IFN-γ) and to improve the clinical efficacy of mesenchymal stem cell (MSC) transplantation (MSCT) in patients with rheumatoid arthritis (RA). METHODS:Study of wild-type or IFN-γR MSCT was first evaluated in a murine model of collagen-induced arthritis (CIA) following which a phase 1/2 randomised controlled study was conducted in 63 patients with RA who responded poorly to regular clinical treatments. Subjects were randomly assigned to an MSCT monotherapy group (n=32) or an MSCT plus recombinant human IFN-γ treatment group (n=31), with 1 year of follow-up. The primary end points consisted of efficacy as assessed as good or moderate EULAR response rates and the proportion of patients at 3 months attaining American College of Rheumatology 20 (ACR20) response rates. RESULTS:In the murine studies, wild-type MSCT significantly improved the clinical severity of CIA, while IFN-γR MSCT aggravated synovitis, and joint and cartilage damage. Transitioning from the murine to the clinical study, the 3-month follow-up results showed that the efficacy and ACR20 response rates were attained in 53.3% patients with MSCT monotherapy and in 93.3% patients with MSCT combined with IFN-γ treatment (p<0.05). No new or unexpected safety issues were encountered in 1-year follow-up for either treatment group. CONCLUSIONS:The results of this study show that IFN-γ is a key factor in determining the efficacy of MSCT in the treatment of RA, and that an MSC plus IFN-γ combination therapeutic strategy can greatly improve the clinical efficacy of MSC-based therapy in RA patients. 10.1136/annrheumdis-2020-217798
    Neutrophils in Rheumatoid Arthritis: Breaking Immune Tolerance and Fueling Disease. O'Neil Liam J,Kaplan Mariana J Trends in molecular medicine Rheumatoid arthritis (RA), a common autoimmune disease, is characterized by a highly coordinated inflammatory response that involves innate and adaptive immunity. One of the hallmarks of RA is an immune response directed at citrullinated peptides that are specifically targeted by anticitrullinated protein antibodies (ACPAs). Among the various mechanisms by which neutrophils may promote immune dysregulation in RA, their ability to extrude neutrophil extracellular traps has recently been implicated in the development of ACPAs. In the synovium, neutrophils interact with resident fibroblast-like synoviocytes to endow them with antigen-presenting cell capabilities and an inflammatory phenotype. Further understanding how neutrophils modulate autoimmunity and tissue damage in RA may lead to the development of novel effective therapies. 10.1016/j.molmed.2018.12.008
    Impaired ATM activation in B cells is associated with bone resorption in rheumatoid arthritis. Mensah Kofi A,Chen Jeff W,Schickel Jean-Nicolas,Isnardi Isabelle,Yamakawa Natsuko,Vega-Loza Andrea,Anolik Jennifer H,Gatti Richard A,Gelfand Erwin W,Montgomery Ruth R,Horowitz Mark C,Craft Joe E,Meffre Eric Science translational medicine Patients with rheumatoid arthritis (RA) may display atypical CD21 B cells in their blood, but the implication of this observation remains unclear. We report here that the group of patients with RA and elevated frequencies of CD21 B cells shows decreased ataxia telangiectasia-mutated (ATM) expression and activation in B cells compared with other patients with RA and healthy donor controls. In agreement with ATM involvement in the regulation of V(D)J recombination, patients with RA who show defective ATM function displayed a skewed B cell receptor (BCR) Igκ repertoire, which resembled that of patients with ataxia telangiectasia (AT). This repertoire was characterized by increased Jκ1 and decreased upstream Vκ gene segment usage, suggesting improper secondary recombination processes and selection. In addition, altered ATM function in B cells was associated with decreased osteoprotegerin and increased receptor activator of nuclear factor κB ligand (RANKL) production. These changes favor bone loss and correlated with a higher prevalence of erosive disease in patients with RA who show impaired ATM function. Using a humanized mouse model, we also show that ATM inhibition in vivo induces an altered Igκ repertoire and RANKL production by immature B cells in the bone marrow, leading to decreased bone density. We conclude that dysregulated ATM function in B cells promotes bone erosion and the emergence of circulating CD21 B cells, thereby contributing to RA pathophysiology. 10.1126/scitranslmed.aaw4626
    Notch signalling drives synovial fibroblast identity and arthritis pathology. Nature The synovium is a mesenchymal tissue composed mainly of fibroblasts, with a lining and sublining that surround the joints. In rheumatoid arthritis the synovial tissue undergoes marked hyperplasia, becomes inflamed and invasive, and destroys the joint. It has recently been shown that a subset of fibroblasts in the sublining undergoes a major expansion in rheumatoid arthritis that is linked to disease activity; however, the molecular mechanism by which these fibroblasts differentiate and expand is unknown. Here we identify a critical role for NOTCH3 signalling in the differentiation of perivascular and sublining fibroblasts that express CD90 (encoded by THY1). Using single-cell RNA sequencing and synovial tissue organoids, we found that NOTCH3 signalling drives both transcriptional and spatial gradients-emanating from vascular endothelial cells outwards-in fibroblasts. In active rheumatoid arthritis, NOTCH3 and Notch target genes are markedly upregulated in synovial fibroblasts. In mice, the genetic deletion of Notch3 or the blockade of NOTCH3 signalling attenuates inflammation and prevents joint damage in inflammatory arthritis. Our results indicate that synovial fibroblasts exhibit a positional identity that is regulated by endothelium-derived Notch signalling, and that this stromal crosstalk pathway underlies inflammation and pathology in inflammatory arthritis. 10.1038/s41586-020-2222-z
    HBEGF macrophages in rheumatoid arthritis induce fibroblast invasiveness. Kuo David,Ding Jennifer,Cohn Ian S,Zhang Fan,Wei Kevin,Rao Deepak A,Rozo Cristina,Sokhi Upneet K,Shanaj Sara,Oliver David J,Echeverria Adriana P,DiCarlo Edward F,Brenner Michael B,Bykerk Vivian P,Goodman Susan M,Raychaudhuri Soumya,Rätsch Gunnar,Ivashkiv Lionel B,Donlin Laura T Science translational medicine Macrophages tailor their function according to the signals found in tissue microenvironments, assuming a wide spectrum of phenotypes. A detailed understanding of macrophage phenotypes in human tissues is limited. Using single-cell RNA sequencing, we defined distinct macrophage subsets in the joints of patients with the autoimmune disease rheumatoid arthritis (RA), which affects ~1% of the population. The subset we refer to as HBEGF inflammatory macrophages is enriched in RA tissues and is shaped by resident fibroblasts and the cytokine tumor necrosis factor (TNF). These macrophages promoted fibroblast invasiveness in an epidermal growth factor receptor-dependent manner, indicating that intercellular cross-talk in this inflamed setting reshapes both cell types and contributes to fibroblast-mediated joint destruction. In an ex vivo synovial tissue assay, most medications used to treat RA patients targeted HBEGF inflammatory macrophages; however, in some cases, medication redirected them into a state that is not expected to resolve inflammation. These data highlight how advances in our understanding of chronically inflamed human tissues and the effects of medications therein can be achieved by studies on local macrophage phenotypes and intercellular interactions. 10.1126/scitranslmed.aau8587
    Immunometabolism in the development of rheumatoid arthritis. Weyand Cornelia M,Goronzy Jörg J Immunological reviews In rheumatoid arthritis (RA), breakdown of self-tolerance and onset of clinical disease are separated in time and space, supporting a multi-hit model in which emergence of autoreactive T cells is a pinnacle pathogenic event. Determining factors in T cell differentiation and survival include antigen recognition, but also the metabolic machinery that provides energy and biosynthetic molecules for cell building. Studies in patients with RA have yielded a disease-specific metabolic signature, which enables naive CD4 T cells to differentiate into pro-inflammatory helper T cells that are prone to invade into tissue and elicit inflammation through immunogenic cell death. A typifying property of RA CD4 T cells is the shunting of glucose away from glycolytic breakdown and mitochondrial processing toward the pentose phosphate pathway, favoring anabolic over catabolic reactions. Key defects have been localized to the mitochondria and the lysosome; including instability of mitochondrial DNA due to the lack of the DNA repair nuclease MRE11A and inefficient lysosomal tethering of AMPK due to deficiency of N-myristoyltransferase 1 (NMT1). The molecular taxonomy of the metabolically reprogrammed RA T cells includes glycolytic enzymes (glucose-6-phosphate dehydrogenase, phosphofructokinase), DNA repair molecules (MRE11A, ATM), regulators of protein trafficking (NMT1), and the membrane adapter protein TSK5. As the mechanisms determining abnormal T cell behavior in RA are unraveled, opportunities will emerge to interject autoimmune T cells by targeting their metabolic checkpoints. 10.1111/imr.12838
    Calcium-sensing receptor-mediated NLRP3 inflammasome response to calciprotein particles drives inflammation in rheumatoid arthritis. Jäger Elisabeth,Murthy Supriya,Schmidt Caroline,Hahn Magdalena,Strobel Sarah,Peters Anna,Stäubert Claudia,Sungur Pelin,Venus Tom,Geisler Mandy,Radusheva Veselina,Raps Stefanie,Rothe Kathrin,Scholz Roger,Jung Sebastian,Wagner Sylke,Pierer Matthias,Seifert Olga,Chang Wenhan,Estrela-Lopis Irina,Raulien Nora,Krohn Knut,Sträter Norbert,Hoeppener Stephanie,Schöneberg Torsten,Rossol Manuela,Wagner Ulf Nature communications Increased extracellular Ca concentrations ([Ca]) trigger activation of the NLRP3 inflammasome in monocytes through calcium-sensing receptor (CaSR). To prevent extraosseous calcification in vivo, the serum protein fetuin-A stabilizes calcium and phosphate into 70-100 nm-sized colloidal calciprotein particles (CPPs). Here we show that monocytes engulf CPPs via macropinocytosis, and this process is strictly dependent on CaSR signaling triggered by increases in [Ca]. Enhanced macropinocytosis of CPPs results in increased lysosomal activity, NLRP3 inflammasome activation, and IL-1β release. Monocytes in the context of rheumatoid arthritis (RA) exhibit increased CPP uptake and IL-1β release in response to CaSR signaling. CaSR expression in these monocytes and local [Ca] in afflicted joints are increased, probably contributing to this enhanced response. We propose that CaSR-mediated NLRP3 inflammasome activation contributes to inflammatory arthritis and systemic inflammation not only in RA, but possibly also in other inflammatory conditions. Inhibition of CaSR-mediated CPP uptake might be a therapeutic approach to treating RA. 10.1038/s41467-020-17749-6
    PAD enzymes in rheumatoid arthritis: pathogenic effectors and autoimmune targets. Curran Ashley M,Naik Pooja,Giles Jon T,Darrah Erika Nature reviews. Rheumatology Peptidylarginine deiminases (PADs) have an important role in the pathogenesis of rheumatoid arthritis (RA) owing to their ability to generate citrullinated proteins - the hallmark autoantigens of RA. Of the five PAD enzyme isoforms, PAD2 and PAD4 are the most strongly implicated in RA at both genetic and cellular levels, and PAD inhibitors have shown therapeutic efficacy in mouse models of inflammatory arthritis. PAD2 and PAD4 are additionally targeted by autoantibodies in distinct clinical subsets of patients with RA, suggesting anti-PAD antibodies as possible biomarkers for RA diagnosis and prognosis. This Review weighs the evidence that supports a pathogenic role for PAD enzymes in RA as both promoters and targets of the autoimmune response, as well as discussing the mechanistic and therapeutic implications of these findings in the wider context of RA pathogenesis. Understanding the origin and consequences of dysregulated PAD enzyme activity and immune responses against PAD enzymes will be important to fully comprehend the pathogenic mechanisms involved in this disease and for the development of novel strategies to treat and prevent RA. 10.1038/s41584-020-0409-1
    Interleukin-17 in rheumatoid arthritis: Trials and tribulations. Taams Leonie S The Journal of experimental medicine Interleukin-17A (IL-17A) is a pro-inflammatory cytokine with well-characterized biological effects on stromal cell activation, angiogenesis, and osteoclastogenesis. The presence of this cytokine in the inflamed joints of patients with rheumatoid arthritis (RA), together with compelling data from in vitro and experimental arthritis models demonstrating its pro-inflammatory effects, made this cytokine a strong candidate for therapeutic targeting. Clinical trials, however, have shown relatively modest success in RA as compared with other indications. Guided by recent insights in IL-17 biology, this review aims to explore possible reasons for the limited clinical efficacy of IL-17A blockade in RA, and what we can learn from these results going forward. 10.1084/jem.20192048
    Regulatory eosinophils induce the resolution of experimental arthritis and appear in remission state of human rheumatoid arthritis. Annals of the rheumatic diseases OBJECTIVES:Eosinophils possess pro-inflammatory functions in asthma. However, our recent studies have suggested that innate lymphoid cells type 2 (ILC2s) and eosinophils have proresolving properties in rheumatoid arthritis (RA). Nothing is known yet about the mechanisms determining the double-edged role of eosinophils. Therefore, we investigated whether asthma, a paradigm eosinophilic disease, can elicit resolution of chronic arthritis. METHODS:Ovalbumin-triggered eosinophilic asthma was combined with K/BxN serum-induced arthritis, where lung and synovial eosinophil subsets were compared by single-cell RNA sequencing (scRNA-seq). To investigate the involvement of the ILC2-interleukin-5 (IL-5) axis, hydrodynamic injection (HDI) of IL-25 and IL-33 plasmids, IL-5 reporter mice and anti-IL-5 antibody treatment were used. In patients with RA, the presence of distinct eosinophil subsets was examined in peripheral blood and synovial tissue. Disease activity of patients with RA with concomitant asthma was monitored before and after mepolizumab (anti-IL-5 antibody) therapy. RESULTS:The induction of eosinophilic asthma caused resolution of murine arthritis and joint tissue protection. ScRNA-seq revealed a specific subset of regulatory eosinophils (rEos) in the joints, distinct from inflammatory eosinophils in the lungs. Mechanistically, synovial rEos expanded on systemic upregulation of IL-5 released by lung ILC2s. Eosinophil depletion abolished the beneficial effect of asthma on arthritis. rEos were consistently present in the synovium of patients with RA in remission, but not in active stage. Remarkably, in patients with RA with concomitant asthma, mepolizumab treatment induced relapse of arthritis. CONCLUSION:These findings point to a hitherto undiscovered proresolving signature in an eosinophil subset that stimulates arthritis resolution. 10.1136/annrheumdis-2020-218902
    Neutrophil-mediated carbamylation promotes articular damage in rheumatoid arthritis. Science advances Formation of autoantibodies to carbamylated proteins (anti-CarP) is considered detrimental in the prognosis of erosive rheumatoid arthritis (RA). The source of carbamylated antigens and the mechanisms by which anti-CarP antibodies promote bone erosion in RA remain unknown. Here, we find that neutrophil extracellular traps (NETs) externalize carbamylated proteins and that RA subjects develop autoantibodies against carbamylated NET (cNET) antigens that, in turn, correlate with levels of anti-CarP. Transgenic mice expressing the human RA shared epitope (HLADRB1* 04:01) immunized with cNETs develop antibodies to citrullinated and carbamylated proteins. Furthermore, anti-carbamylated histone antibodies correlate with radiographic bone erosion in RA subjects. Moreover, anti-carbamylated histone-immunoglobulin G immune complexes promote osteoclast differentiation and potentiate osteoclast-mediated matrix resorption. These results demonstrate that carbamylated proteins present in NETs enhance pathogenic immune responses and bone destruction, which may explain the association between anti-CarP and erosive arthritis in RA. 10.1126/sciadv.abd2688
    Analysis of chromatin organization and gene expression in T cells identifies functional genes for rheumatoid arthritis. Yang Jing,McGovern Amanda,Martin Paul,Duffus Kate,Ge Xiangyu,Zarrineh Peyman,Morris Andrew P,Adamson Antony,Fraser Peter,Rattray Magnus,Eyre Stephen Nature communications Genome-wide association studies have identified genetic variation contributing to complex disease risk. However, assigning causal genes and mechanisms has been more challenging because disease-associated variants are often found in distal regulatory regions with cell-type specific behaviours. Here, we collect ATAC-seq, Hi-C, Capture Hi-C and nuclear RNA-seq data in stimulated CD4+ T cells over 24 h, to identify functional enhancers regulating gene expression. We characterise changes in DNA interaction and activity dynamics that correlate with changes in gene expression, and find that the strongest correlations are observed within 200 kb of promoters. Using rheumatoid arthritis as an example of T cell mediated disease, we demonstrate interactions of expression quantitative trait loci with target genes, and confirm assigned genes or show complex interactions for 20% of disease associated loci, including FOXO1, which we confirm using CRISPR/Cas9. 10.1038/s41467-020-18180-7
    Persistently activated, proliferative memory autoreactive B cells promote inflammation in rheumatoid arthritis. Kristyanto Hendy,Blomberg Nienke J,Slot Linda M,van der Voort Ellen I H,Kerkman Priscilla F,Bakker Aleida,Burgers Leonie E,Ten Brinck Robin M,van der Helm-van Mil Annette H M,Spits Hergen,Baeten Dominique L,Huizinga Tom W J,Toes René E M,Scherer Hans U Science translational medicine Autoreactive B cells mediate autoimmune pathology, but exactly how remains unknown. A hallmark of rheumatoid arthritis (RA), a common autoimmune disease, is the presence of disease-specific anticitrullinated protein antibodies (ACPAs). Here, we showed that ACPA-positive B cells in patients with RA strongly expressed T cell-stimulating ligands, produced abundant proinflammatory cytokines, and were proliferative while escaping inhibitory signals. This activated state was found at different degrees in different stages of disease: highest in patients with recent-onset RA, moderate in patients with established RA, and far less pronounced in ACPA-positive individuals "at risk" for developing disease. The activated autoreactive B cell response persisted in patients who achieved clinical remission with conventional treatment. ACPA-positive B cells in blood and synovial fluid secreted increased amounts of the chemoattractant interleukin-8, which attracted neutrophils, the most abundant immune cell in arthritic joints. Tetanus toxoid-specific B cells from the same patients exhibited properties of memory B cells without the activation and proliferation phenotype, but these cells transiently acquired a similar proliferative phenotype upon booster vaccination. Together, these data indicated that continuous antigenic triggering of autoreactive B cells occurs in human autoimmune disease and support the emerging concept of immunological activity that persists under treatment even in clinical remission, which may revise our current concept of treatment targets for future therapeutic interventions. In addition, our data pointed to a pathogenic role of ACPA-positive B cells in the inflammatory disease process underlying RA and favor approaches that aim at their antigen-specific inactivation or depletion. 10.1126/scitranslmed.aaz5327
    Autoantibodies and B Cells: The ABC of rheumatoid arthritis pathophysiology. Volkov Mikhail,van Schie Karin Anna,van der Woude Diane Immunological reviews Rheumatoid arthritis (RA) is an autoimmune disease characterized by joint inflammation. In the last few decades, new insights into RA-specific autoantibodies and B cells have greatly expanded our understanding of the disease. The best-known autoantibodies in RA-rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA)-are present long before disease onset, and both responses show signs of maturation around the time of the first manifestation of arthritis. A very intriguing characteristic of ACPA is their remarkably high abundance of variable domain glycans. Since these glycans may convey an important selection advantage of citrulline-reactive B cells, they may be the key to understanding the evolution of the autoimmune response. Recently discovered autoantibodies targeting other posttranslational modifications, such as anti-carbamylated and anti-acetylated protein antibodies, appear to be closely related to ACPA, which makes it possible to unite them under the term of anti-modified protein antibodies (AMPA). Despite the many insights gained about these autoantibodies, it is unclear whether they are pathogenic or play a causal role in disease development. Autoreactive B cells from which the autoantibodies originate have also received attention as perhaps more likely disease culprits. The development of autoreactive B cells in RA largely depends on the interaction with T cells in which HLA "shared epitope" and HLA DERAA may play an important role. Recent technological advances made it possible to identify and characterize citrulline-reactive B cells and acquire ACPA monoclonal antibodies, which are providing valuable insights and help to understand the nature of the autoimmune response underlying RA. In this review, we summarize what is currently known about the role of autoantibodies and autoreactive B cells in RA and we discuss the most prominent hypotheses aiming to explain the origins and the evolution of autoimmunity in RA. 10.1111/imr.12829
    Restoring synovial homeostasis in rheumatoid arthritis by targeting fibroblast-like synoviocytes. Nygaard Gyrid,Firestein Gary S Nature reviews. Rheumatology Rheumatoid arthritis (RA) is a chronic immune-mediated disease that primarily affects the synovium of diarthrodial joints. During the course of RA, the synovium transforms into a hyperplastic invasive tissue that causes destruction of cartilage and bone. Fibroblast-like synoviocytes (FLS), which form the lining of the joint, are epigenetically imprinted with an aggressive phenotype in RA and have an important role in these pathological processes. In addition to producing the extracellular matrix and joint lubricants, FLS in RA produce pathogenic mediators such as cytokines and proteases that contribute to disease pathogenesis and perpetuation. The development of multi-omics integrative analyses have enabled new ways to dissect the mechanisms that imprint FLS, have helped to identify potential FLS subsets with distinct functions and have identified differences in FLS phenotypes between joints in individual patients. This Review provides an overview of advances in understanding of FLS biology and highlights omics approaches and studies that hold promise for identifying future therapeutic targets. 10.1038/s41584-020-0413-5
    Distinct synovial tissue macrophage subsets regulate inflammation and remission in rheumatoid arthritis. Alivernini Stefano,MacDonald Lucy,Elmesmari Aziza,Finlay Samuel,Tolusso Barbara,Gigante Maria Rita,Petricca Luca,Di Mario Clara,Bui Laura,Perniola Simone,Attar Moustafa,Gessi Marco,Fedele Anna Laura,Chilaka Sabarinadh,Somma Domenico,Sansom Stephen N,Filer Andrew,McSharry Charles,Millar Neal L,Kirschner Kristina,Nerviani Alessandra,Lewis Myles J,Pitzalis Costantino,Clark Andrew R,Ferraccioli Gianfranco,Udalova Irina,Buckley Christopher D,Gremese Elisa,McInnes Iain B,Otto Thomas D,Kurowska-Stolarska Mariola Nature medicine Immune-regulatory mechanisms of drug-free remission in rheumatoid arthritis (RA) are unknown. We hypothesized that synovial tissue macrophages (STM), which persist in remission, contribute to joint homeostasis. We used single-cell transcriptomics to profile 32,000 STMs and identified phenotypic changes in patients with early/active RA, treatment-refractory/active RA and RA in sustained remission. Each clinical state was characterized by different frequencies of nine discrete phenotypic clusters within four distinct STM subpopulations with diverse homeostatic, regulatory and inflammatory functions. This cellular atlas, combined with deep-phenotypic, spatial and functional analyses of synovial biopsy fluorescent activated cell sorted STMs, revealed two STM subpopulations (MerTKTREM2 and MerTKLYVE1) with unique remission transcriptomic signatures enriched in negative regulators of inflammation. These STMs were potent producers of inflammation-resolving lipid mediators and induced the repair response of synovial fibroblasts in vitro. A low proportion of MerTK STMs in remission was associated with increased risk of disease flare after treatment cessation. Therapeutic modulation of MerTK STM subpopulations could therefore be a potential treatment strategy for RA. 10.1038/s41591-020-0939-8
    Circulating microbial small RNAs are altered in patients with rheumatoid arthritis. Ormseth Michelle J,Wu Qiong,Zhao Shilin,Allen Ryan M,Solus Joseph,Sheng Quanhu,Guo Yan,Ye Fei,Ramirez-Solano Marisol,Bridges S Louis,Curtis Jeffrey R,Vickers Kasey,Stein C Michael Annals of the rheumatic diseases OBJECTIVES:To determine if plasma microbial small RNAs (sRNAs) are altered in patients with rheumatoid arthritis (RA) compared with control subjects, associated with RA disease-related features, and altered by disease-modifying antirheumatic drugs (DMARDs). METHODS:sRNA sequencing was performed on plasma from 165 patients with RA and 90 matched controls and a separate cohort of 70 patients with RA before and after starting a DMARD. Genome alignments for RA-associated bacteria, representative bacterial and fungal human microbiome genomes and environmental bacteria were performed. Microbial genome counts and individual sRNAs were compared across groups and correlated with disease features. False discovery rate was set at 0.05. RESULTS:Genome counts of , , , spp, , spp, and were significantly decreased in the plasma of RA compared with control subjects. Three microbial transfer RNA-derived sRNAs were increased in RA versus controls and inversely associated with disease activity. Higher total microbial sRNA reads were associated with lower disease activity in RA. Baseline total microbial sRNAs were threefold higher among patients who improved with DMARD versus those who did not but did not change significantly after 6 months of treatment. CONCLUSION:Plasma microbial sRNA composition is altered in RA versus control subjects and associated with some measures of RA disease activity. DMARD treatment does not alter microbial sRNA abundance or composition, but increased abundance of microbial sRNAs at baseline was associated with disease activity improvement at 6 months. 10.1136/annrheumdis-2020-217589
    Rheumatoid Arthritis. Sparks Jeffrey A Annals of internal medicine Rheumatoid arthritis (RA) is a common systemic inflammatory autoimmune disease characterized by painful, swollen joints that can severely impair physical function and quality of life. The presenting symptoms of musculoskeletal pain, swelling, and stiffness are common in clinical practice, so familiarity with diagnosing and managing RA is crucial. Patients with RA are at greater risk for serious infection, respiratory disease, osteoporosis, cardiovascular disease, cancer, and mortality than the general population. In recent years, early diagnosis, aggressive treatment, and expanded therapeutic options of disease-modifying antirheumatic drugs have markedly improved both the management and long-term prognosis of RA. 10.7326/AITC201901010
    Route to Rheumatoid Arthritis by Macrophage-Derived Microvesicle-Coated Nanoparticles. Li Ruixiang,He Yuwei,Zhu Ying,Jiang Lixian,Zhang Shuya,Qin Jing,Wu Qian,Dai Wentao,Shen Shun,Pang Zhiqing,Wang Jianxin Nano letters The targeted delivery of therapeutics to sites of rheumatoid arthritis (RA) has been a long-standing challenge. Inspired by the intrinsic inflammation-targeting capacity of macrophages, a macrophage-derived microvesicle (MMV)-coated nanoparticle (MNP) was developed for targeting RA. The MMV was efficiently produced through a novel method. Cytochalasin B (CB) was applied to relax the interaction between the cytoskeleton and membrane of macrophages, thus stimulating MMV secretion. The proteomic profile of the MMV was analyzed by iTRAQ (isobaric tags for relative and absolute quantitation). The MMV membrane proteins were similar to those of macrophages, indicating that the MMV could exhibit bioactivity similar to that of RA-targeting macrophages. A poly(lactic- co-glycolic acid) (PLGA) nanoparticle was subsequently coated with MMV, and the inflammation-mediated targeting capacity of the MNP was evaluated both in vitro and in vivo. The in vitro binding of MNP to inflamed HUVECs was significantly stronger than that of the red blood cell membrane-coated nanoparticle (RNP). Compared with bare NP and RNP, MNP showed a significantly enhanced targeting effect in vivo in a collagen-induced arthritis (CIA) mouse model. The targeting mechanism was subsequently revealed according to the proteomic analysis, indicating that Mac-1 and CD44 contributed to the outstanding targeting effect of the MNP. A model drug, tacrolimus, was encapsulated in MNP (T-RNP) and significantly suppressed the progression of RA in mice. The present study demonstrates MMV as a promising and rich material, with which to mimic macrophages, and demonstrates that MNP is an efficient biomimetic vehicle for RA targeting and treatment. 10.1021/acs.nanolett.8b03439
    HIF1α inhibition facilitates Leflunomide-AHR-CRP signaling to attenuate bone erosion in CRP-aberrant rheumatoid arthritis. Liang Chao,Li Jie,Lu Cheng,Xie Duoli,Liu Jin,Zhong Chuanxin,Wu Xiaohao,Dai Rongchen,Zhang Huarui,Guan Daogang,Guo Baosheng,He Bing,Li Fangfei,He Xiaojuan,Zhang Wandong,Zhang Bao-Ting,Zhang Ge,Lu Aiping Nature communications Rheumatoid arthritis (RA) is a chronic inflammatory disorder characterized by progressive bone erosion. Leflunomide is originally developed to suppress inflammation via its metabolite A77 1726 to attenuate bone erosion. However, distinctive responsiveness to Leflunomide is observed among RA individuals. Here we show that Leflunomide exerts immunosuppression but limited efficacy in RA individuals distinguished by higher serum C-reactive protein (CRP, CRP), whereas the others with satisfactory responsiveness to Leflunomide show lower CRP (CRP, CRP). CRP inhibition decreases bone erosion in arthritic rats. Besides the immunomodulation via A77 1726, Leflunomide itself induces AHR-ARNT interaction to inhibit hepatic CRP production and attenuate bone erosion in CRP arthritic rats. Nevertheless, high CRP in CRP rats upregulates HIF1α, which competes with AHR for ARNT association and interferes Leflunomide-AHR-CRP signaling. Hepatocyte-specific HIF1α deletion or a HIF1α inhibitor Acriflavine re-activates Leflunomide-AHR-CRP signaling to inhibit bone erosion. This study presents a precision medicine-based therapeutic strategy for RA. 10.1038/s41467-019-12163-z
    MICL controls inflammation in rheumatoid arthritis. Redelinghuys Pierre,Whitehead Lauren,Augello Andrea,Drummond Rebecca A,Levesque Jean-Michel,Vautier Simon,Reid Delyth M,Kerscher Bernhard,Taylor Julie A,Nigrovic Peter A,Wright John,Murray Graeme I,Willment Janet A,Hocking Lynne J,Fernandes Maria J G,De Bari Cosimo,Mcinnes Iain B,Brown Gordon D Annals of the rheumatic diseases BACKGROUND:Myeloid inhibitory C-type lectin-like receptor (MICL, Clec12A) is a C-type lectin receptor (CLR) expressed predominantly by myeloid cells. Previous studies have suggested that MICL is involved in controlling inflammation. OBJECTIVE:To determine the role of this CLR in inflammatory pathology using Clec12A(-/-) mice. METHODS:Clec12A(-/-) mice were generated commercially and primarily characterised using the collagen antibody-induced arthritis (CAIA) model. Mechanisms and progress of disease were characterised by clinical scoring, histology, flow cytometry, irradiation bone-marrow chimera generation, administration of blocking antibodies and in vivo imaging. Characterisation of MICL in patients with rheumatoid arthritis (RA) was determined by immunohistochemistry and single nucleotide polymorphism analysis. Anti-MICL antibodies were detected in patient serum by ELISA and dot-blot analysis. RESULTS:MICL-deficient animals did not present with pan-immune dysfunction, but exhibited markedly exacerbated inflammation during CAIA, owing to the inappropriate activation of myeloid cells. Polymorphisms of MICL were not associated with disease in patients with RA, but this CLR was the target of autoantibodies in a subset of patients with RA. In wild-type mice the administration of such antibodies recapitulated the Clec12A(-/-) phenotype. CONCLUSIONS:MICL plays an essential role in regulating inflammation during arthritis and is an autoantigen in a subset of patients with RA. These data suggest an entirely new mechanism underlying RA pathogenesis, whereby the threshold of myeloid cell activation can be modulated by autoantibodies that bind to cell membrane-expressed inhibitory receptors. 10.1136/annrheumdis-2014-206644
    Targeting lymphatic function as a novel therapeutic intervention for rheumatoid arthritis. Bouta Echoe M,Bell Richard D,Rahimi Homaira,Xing Lianping,Wood Ronald W,Bingham Clifton O,Ritchlin Christopher T,Schwarz Edward M Nature reviews. Rheumatology Although clinical outcomes for patients with rheumatoid arthritis (RA) have greatly improved with the use of biologic and conventional DMARDs, approximately 40% of patients do not achieve primary clinical outcomes in randomized trials, and only a small proportion achieve lasting remission. Over the past decade, studies in murine models point to the critical role of the lymphatic system in the pathogenesis and therapy of inflammatory-erosive arthritis, presumably by the removal of catabolic factors, cytokines and inflammatory cells from the inflamed synovium. Murine studies demonstrate that lymphatic drainage increases at the onset of inflammatory-erosive arthritis but, as inflammation progresses to a more chronic phase, lymphatic clearance declines and both structural and cellular changes are observed in the draining lymph node. Specifically, chronic damage to the lymphatic vessel from persistent inflammation results in loss of lymphatic vessel contraction followed by lymph node collapse, reduced lymphatic drainage, and ultimately severe synovitis and joint erosion. Notably, clinical pilot studies in patients with RA report lymph node changes following treatment, and thus draining lymphatic vessels and nodes could represent a potential biomarker of arthritis activity and response to therapy. Most importantly, targeting lymphatics represents an innovative strategy for therapeutic intervention for RA. 10.1038/nrrheum.2017.205
    Novel treatment strategies in rheumatoid arthritis. Burmester Gerd R,Pope Janet E Lancet (London, England) New treatment strategies have substantially changed the course of rheumatoid arthritis. Many patients can achieve remission if the disease is recognised early and is treated promptly and continuously; however, some individuals do not respond adequately to treatment. Rapid diagnosis and a treat-to-target approach with tight monitoring and control, can increase the likelihood of remission in patients with rheumatoid arthritis. In this Series paper, we describe new insights into the management of rheumatoid arthritis with targeted therapy approaches using classic and novel medications, and outline the potential effects of precision medicine in this challenging disease. Articles are included that investigate the treat-to-target approach, which includes adding or de-escalating treatment. Rheumatoid arthritis treatment is impeded by delayed diagnosis, problematic access to specialists, and difficulties adhering to treat-to-target principles. Clinical management goals in rheumatoid arthritis include enabling rapid access to optimum diagnosis and care and the well informed use of multiple treatments approved for this disease. 10.1016/S0140-6736(17)31491-5
    Synergistic Oxygen Generation and Reactive Oxygen Species Scavenging by Manganese Ferrite/Ceria Co-decorated Nanoparticles for Rheumatoid Arthritis Treatment. Kim Jonghoon,Kim Han Young,Song Seuk Young,Go Seok-Hyeong,Sohn Hee Su,Baik Seungmin,Soh Min,Kim Kang,Kim Dokyoon,Kim Hyo-Cheol,Lee Nohyun,Kim Byung-Soo,Hyeon Taeghwan ACS nano Poor O supply to the infiltrated immune cells in the joint synovium of rheumatoid arthritis (RA) up-regulates hypoxia-inducible factor (HIF-1α) expression and induces reactive oxygen species (ROS) generation, both of which exacerbate synovial inflammation. Synovial inflammation in RA can be resolved by eliminating pro-inflammatory M1 macrophages and inducing anti-inflammatory M2 macrophages. Because hypoxia and ROS in the RA synovium play a crucial role in the induction of M1 macrophages and reduction of M2 macrophages, herein, we develop manganese ferrite and ceria nanoparticle-anchored mesoporous silica nanoparticles (MFC-MSNs) that can synergistically scavenge ROS and produce O for reducing M1 macrophage levels and inducing M2 macrophages for RA treatment. MFC-MSNs exhibit a synergistic effect on O generation and ROS scavenging that is attributed to the complementary reaction of ceria nanoparticles (NPs) that can scavenge intermediate hydroxyl radicals generated by manganese ferrite NPs in the process of O generation during the Fenton reaction, leading to the efficient polarization of M1 to M2 macrophages both in vitro and in vivo. Intra-articular administration of MFC-MSNs to rat RA models alleviated hypoxia, inflammation, and pathological features in the joint. Furthermore, MSNs were used as a drug-delivery vehicle, releasing the anti-rheumatic drug methotrexate in a sustained manner to augment the therapeutic effect of MFC-MSNs. This study highlights the therapeutic potential of MFC-MSNs that simultaneously generate O and scavenge ROS, subsequently driving inflammatory macrophages to the anti-inflammatory subtype for RA treatment. 10.1021/acsnano.8b08785
    Defining refractory rheumatoid arthritis. Buch Maya H Annals of the rheumatic diseases While biologic disease-modifying antirheumatic drugs (bDMARDs) have transformed outcomes of people with rheumatoid arthritis (RA), a proportion of patients are refractory to multiple bDMARDs. Definitions of refractory RA thus far have been arbitrary, and outcome data and impact of such cohorts remain limited. Extrapolation from randomised controlled trial and some real-life data suggest approximately 20% progress onto a third bDMARD with a more modest proportion failing additional bDMARDs. This viewpoint discusses an opinion of refractory RA disease and proposes key principles to accurately identify refractory cohorts. These include demonstrating presence of persistent inflammation despite multiple therapies and acknowledging development of antidrug antibody. Potential basis of refractory disease is summarised, and suggestions for an initial approach in the future evaluation of refractory disease are offered. Specific investigation of refractory RA disease is necessary to inform the clinical need and provide a basis for robust investigation of underlying mechanisms. 10.1136/annrheumdis-2017-212862
    Maresin 1 improves the Treg/Th17 imbalance in rheumatoid arthritis through miR-21. Jin Shengwei,Chen Huaijun,Li Yongsheng,Zhong Hao,Sun Weiwei,Wang Jianmin,Zhang Tingting,Ma Jinglan,Yan Songfan,Zhang Jiangang,Tian Qingqing,Yang Xinyu,Wang Jianguang Annals of the rheumatic diseases OBJECTIVE:Treg/Th17 imbalance plays an important role in rheumatoid arthritis (RA). Maresin 1 (MaR1) prompts inflammation resolution and regulates immune responses. We explored the effect of MaR1 on RA progression and investigated the correlation between MaR1 and Treg/Th17 balance. METHODS:Both patients with RA and healthy controls were recruited into the study. Collagen-induced arthritis (CIA) model was constructed to detect the clinical score, histopathological changes and Treg/Th17 ratio. Purified naive CD4+ T-cells were used to study the effect of MaR1 on its differentiation process and microRNA microarray studies were performed to investigate MaR1 downstream microRNAs in this process. MicroRNA transfection experiments were conducted by lentivirus to verify the mechanism of MaR1 on Treg/Th17 balance. RESULTS:Compared with controls, the MaR1 concentration was higher in the patients with inactive RA and lower in the patients with active RA. Expression of the Treg transcription factor FoxP3 was the highest in inactive RA and the lowest in active RA, while the Th17 transcription factor RORc showed a reverse trend. An inverse correlation was observed between the FoxP3/RORc ratio and Disease Activity Score 28. Intervention of MaR1 in the CIA model reduced joint inflammation and damage, and improved the imbalanced Treg/Th17 ratio. MaR1 increased Treg cells proportion while reduced Th17 cells proportion under specific differentiation conditions. Furthermore, miR-21 was verified as MaR1 downstream microRNA, which was upregulated by MaR1, modulating the Treg/Th17 balance and thus ameliorating the RA progression. CONCLUSIONS:MaR1 is a therapeutic target for RA, likely operating through effects on the imbalanced Treg/Th17 ratio found in the disease. 10.1136/annrheumdis-2018-213511
    CD109 regulates the inflammatory response and is required for the pathogenesis of rheumatoid arthritis. Song Guanhua,Feng Tingting,Zhao Ru,Lu Qiqi,Diao Yutao,Guo Qingwei,Wang Zhaoxia,Zhang Yuang,Ge Luna,Pan Jihong,Wang Lin,Han Jinxiang Annals of the rheumatic diseases OBJECTIVE:The aim of this study was to investigate the role of CD109 in rheumatoid arthritis (RA) fibroblast-like synoviocytes (FLSs) and to evaluate its potential as a therapeutic target. METHODS:CD109 expression was examined in synovial tissues and FLSs from RA patients and collagen-induced arthritis (CIA) model mice. CD109-deficient mice were developed to evaluate the severity of CIA. Small interfering RNAs and a neutralising antibody against CD109 (anti-CD109) were designed for functional or treatment studies in RA FLSs and CIA. RESULTS:CD109 was found to be abundantly expressed in the synovial tissues from RA patients and CIA mice. CD109 expression in RA FLSs was upregulated by inflammatory stimuli, such as interleukin-1β and tumour necrosis factor-α. Silencing of CD109 or anti-CD109 treatment reduced proinflammatory factor production, cell migration, invasion, chemoattractive potential and osteoclast differentiation, thereby reducing the deleterious inflammatory response of RA FLSs in vitro. Mice lacking CD109 were protected against arthritis in the CIA model. Anti-CD109 treatment prevented the onset and ameliorated the severity of CIA lesions. CONCLUSION:Our study uncovers an antiarthritic role for CD109 and suggests that CD109 inhibition might serve as a promising novel therapeutic strategy for RA. 10.1136/annrheumdis-2019-215473
    Melatonin attenuates TNF-α and IL-1β expression in synovial fibroblasts and diminishes cartilage degradation: Implications for the treatment of rheumatoid arthritis. Huang Chien-Chung,Chiou Chen-Hsiang,Liu Shan-Chi,Hu Sung-Lin,Su Chen-Ming,Tsai Chun-Hao,Tang Chih-Hsin Journal of pineal research The hormone melatonin has many properties, including antioxidant, anti-inflammatory, and immunomodulatory effects. Melatonin has been demonstrated to be beneficial in several inflammatory autoimmune diseases, but its effects in rheumatoid arthritis (RA) remain controversial. We sought to determine how melatonin regulates inflammation in RA. We found that melatonin dose-dependently inhibits tumor necrosis factor-α (TNF-α) and interleukin (IL)-1β expression through the PI3K/AKT, ERK, and NF-κB signaling pathways. We also identified that melatonin inhibits TNF-α and IL-1β production by upregulating miR-3150a-3p expression. Synovial tissue specimens from RA patients and culture of human rheumatoid fibroblast-like synoviocytes confirmed that the MT1 receptor is needed for the anti-inflammatory activities of melatonin. Importantly, melatonin also significantly reduced paw swelling, cartilage degradation, and bone erosion in the collagen-induced arthritis mouse model. Our results indicate that melatonin ameliorates RA by inhibiting TNF-α and IL-1β production through downregulation of the PI3K/AKT, ERK, NF-κB signaling pathways, as well as miR-3150a-3p overexpression. The role of melatonin as an adjuvant treatment in patients with RA deserves further clinical studies. 10.1111/jpi.12560