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    C3a-C3aR signaling promotes breast cancer lung metastasis via modulating carcinoma associated fibroblasts. Shu Chi,Zha Haoran,Long Haixia,Wang Xinxin,Yang Fei,Gao Jianbao,Hu Chunyan,Zhou Li,Guo Bo,Zhu Bo Journal of experimental & clinical cancer research : CR BACKGROUND:Mounting evidence suggests that complement components promote tumor progression via modulating immune suppression, angiogenesis, or tumor cell proliferation. However, the role of C3a-C3aR signaling in regulating lung metastasis of breast cancer remains unknown. METHODS:We performed various ex-vivo and in-vivo assays. Genetic and pharmacological C3aR blockade models were applied to investigate the role of C3a-C3aR in metastasis of breast cancer. RESULTS:C3a-C3aR signaling in CAFs facilitates the metastasis of breast cancer. Mechanically, C3a-C3aR signaling augments pro-metastatic cytokine secretion and extracellular matrix components expression of CAFs via the activation of PI3K-AKT signaling. Genetic or pharmacological blockade of C3aR signaling effectively inhibited lung metastasis of breast cancer in mouse models. CONCLUSIONS:C3a-C3aR signaling in CAFs facilitates the metastasis of breast cancer. Targeting C3aR signaling is a potential anti-metastasis strategy for breast cancer therapy. 10.1186/s13046-019-1515-2
    Structural basis for therapeutic inhibition of complement C5. Jore Matthijs M,Johnson Steven,Sheppard Devon,Barber Natalie M,Li Yang I,Nunn Miles A,Elmlund Hans,Lea Susan M Nature structural & molecular biology Activation of complement C5 generates the potent anaphylatoxin C5a and leads to pathogen lysis, inflammation and cell damage. The therapeutic potential of C5 inhibition has been demonstrated by eculizumab, one of the world's most expensive drugs. However, the mechanism of C5 activation by C5 convertases remains elusive, thus limiting development of therapeutics. Here we identify and characterize a new protein family of tick-derived C5 inhibitors. Structures of C5 in complex with the new inhibitors, the phase I and phase II inhibitor OmCI, or an eculizumab Fab reveal three distinct binding sites on C5 that all prevent activation of C5. The positions of the inhibitor-binding sites and the ability of all three C5-inhibitor complexes to competitively inhibit the C5 convertase conflict with earlier steric-inhibition models, thus suggesting that a priming event is needed for activation. 10.1038/nsmb.3196
    Igniting the flame in arthritis: C5aR2 controls endothelial transcytosis of C5a. Köhl Jörg Science immunology C5aR2 transports C5a generated in the arthritic joint to the blood vessel endothelium as the first step in C5aR1-driven neutrophil arrest and crawling. 10.1126/sciimmunol.aax0352
    Complement Receptor C5aR1 Plays an Evolutionarily Conserved Role in Successful Cardiac Regeneration. Natarajan Niranjana,Abbas Yamen,Bryant Donald M,Gonzalez-Rosa Juan Manuel,Sharpe Michka,Uygur Aysu,Cocco-Delgado Lucas H,Ho Nhi Ngoc,Gerard Norma P,Gerard Craig J,MacRae Calum A,Burns Caroline E,Burns C Geoffrey,Whited Jessica L,Lee Richard T Circulation BACKGROUND:Defining conserved molecular pathways in animal models of successful cardiac regeneration could yield insight into why adult mammals have inadequate cardiac regeneration after injury. Insight into the transcriptomic landscape of early cardiac regeneration from model organisms will shed light on evolutionarily conserved pathways in successful cardiac regeneration. METHODS:Here we describe a cross-species transcriptomic screen in 3 model organisms for cardiac regeneration: axolotl, neonatal mice, and zebrafish. Apical resection to remove ≈10% to 20% of ventricular mass was carried out in these model organisms. RNA-sequencing analysis was performed on the hearts harvested at 3 time points: 12, 24, and 48 hours after resection. Sham surgery was used as internal control. RESULTS:Genes associated with inflammatory processes were found to be upregulated in a conserved manner. Complement receptors (activated by complement components, part of the innate immune system) were found to be highly upregulated in all 3 species. This approach revealed induction of gene expression for complement 5a receptor 1 in the regenerating hearts of zebrafish, axolotls, and mice. Inhibition of complement 5a receptor 1 significantly attenuated the cardiomyocyte proliferative response to heart injury in all 3 species. Furthermore, after left ventricular apical resection, the cardiomyocyte proliferative response was diminished in mice with genetic deletion of complement 5a receptor 1. CONCLUSIONS:These data reveal that activation of complement 5a receptor 1 mediates an evolutionarily conserved response that promotes cardiomyocyte proliferation after cardiac injury and identify complement pathway activation as a common pathway of successful heart regeneration. 10.1161/CIRCULATIONAHA.117.030801
    T helper 1 immunity requires complement-driven NLRP3 inflammasome activity in CD4⁺ T cells. Arbore Giuseppina,West Erin E,Spolski Rosanne,Robertson Avril A B,Klos Andreas,Rheinheimer Claudia,Dutow Pavel,Woodruff Trent M,Yu Zu Xi,O'Neill Luke A,Coll Rebecca C,Sher Alan,Leonard Warren J,Köhl Jörg,Monk Pete,Cooper Matthew A,Arno Matthew,Afzali Behdad,Lachmann Helen J,Cope Andrew P,Mayer-Barber Katrin D,Kemper Claudia Science (New York, N.Y.) The NLRP3 inflammasome controls interleukin-1β maturation in antigen-presenting cells, but a direct role for NLRP3 in human adaptive immune cells has not been described. We found that the NLRP3 inflammasome assembles in human CD4(+) T cells and initiates caspase-1-dependent interleukin-1β secretion, thereby promoting interferon-γ production and T helper 1 (T(H)1) differentiation in an autocrine fashion. NLRP3 assembly requires intracellular C5 activation and stimulation of C5a receptor 1 (C5aR1), which is negatively regulated by surface-expressed C5aR2. Aberrant NLRP3 activity in T cells affects inflammatory responses in human autoinflammatory disease and in mouse models of inflammation and infection. Our results demonstrate that NLRP3 inflammasome activity is not confined to "innate immune cells" but is an integral component of normal adaptive T(H)1 responses. 10.1126/science.aad1210
    Complementing Lung Cancer: How Tumor Cells Co-opt the Host Complement System to Reach Bone. Roman Jesse American journal of respiratory and critical care medicine 10.1164/rccm.201801-0032ED
    Macrophage scavenger receptor 1 contributes to pathogenesis of fulminant hepatitis via neutrophil-mediated complement activation. Tang Yuan,Li Huifang,Li Junru,Liu Yunzhi,Li Yanli,Zhou Jing,Zhou Jia,Lu Xiao,Zhao Wei,Hou Jinlin,Wang Xiang-Yang,Chen Zhengliang,Zuo Daming Journal of hepatology BACKGROUND & AIMS:The macrophage scavenger receptor 1 (Msr1, also called SRA) is a pattern recognition receptor primarily expressed on myeloid cells, which plays an important role in the maintenance of immune homeostasis. Since MSR1 expression was upregulated in the livers of patients with fulminant hepatitis (FH), we investigated the functional mechanism of Msr1 in FH pathogenesis. METHODS:Msr1-deficient (Msr1) mice and their wild-type (WT) littermates were infected with mouse hepatitis virus strain-A59 (MHV-A59) to induce FH, and the levels of tissue damage, serum alanine aminotransferase, inflammatory cytokines and complement component 5a (C5a) were measured and compared. Liver injury was studied after MHV infection with or without neutrophil depletion. RESULTS:Our results showed that Msr1 mice were resistant to MHV-induced hepatitis. Treatment with the C5a receptor antagonist (C5aRa) diminished the differences in inflammatory responses and liver injury between MHV-infected wild-type and Msr1 mice, suggesting that C5a-induced pro-inflammatory response plays a critical role in the Msr1-mediated regulation of FH pathogenesis. We demonstrated that Msr1 efficiently enhanced transforming growth factor-activated kinase-1 phosphorylation in neutrophils upon MHV-A59 stimulation, thereby promoting the activation of the extracellular signal-regulated kinase pathway and subsequent NETosis formation. Moreover, we provided evidence that blockage of Msr1 attenuated the liver damage caused by MHV-A59 infection. CONCLUSIONS:Msr1 promotes the pathogenesis of virus-induced FH by enhancing induction of neutrophil NETosis and subsequent complement activation. Targeting Msr1 may be employed as a new immunotherapeutic strategy for FH. LAY SUMMARY:Virus-induced fulminant hepatitis (FH) is a disease with a high mortality worldwide. Enhanced levels of macrophage scavenger receptor 1 (Msr1) in the liver of patients with FH and of murine experimental FH indicated Msr1 plays a role in the pathogenesis of FH. Herein, we demonstrate that mice deficient in Msr1 are resistant to FH induced by MHV-A59, and the Msr1 inhibitor fucoidan suppresses the progression of FH in mice. Our study suggests that use of drugs inhibiting MSR1 function could be beneficial to patients with FH. 10.1016/j.jhep.2017.11.010
    Complement drives glucosylceramide accumulation and tissue inflammation in Gaucher disease. Pandey Manoj K,Burrow Thomas A,Rani Reena,Martin Lisa J,Witte David,Setchell Kenneth D,Mckay Mary A,Magnusen Albert F,Zhang Wujuan,Liou Benjamin,Köhl Jörg,Grabowski Gregory A Nature Gaucher disease is caused by mutations in GBA1, which encodes the lysosomal enzyme glucocerebrosidase (GCase). GBA1 mutations drive extensive accumulation of glucosylceramide (GC) in multiple innate and adaptive immune cells in the spleen, liver, lung and bone marrow, often leading to chronic inflammation. The mechanisms that connect excess GC to tissue inflammation remain unknown. Here we show that activation of complement C5a and C5a receptor 1 (C5aR1) controls GC accumulation and the inflammatory response in experimental and clinical Gaucher disease. Marked local and systemic complement activation occurred in GCase-deficient mice or after pharmacological inhibition of GCase and was associated with GC storage, tissue inflammation and proinflammatory cytokine production. Whereas all GCase-inhibited mice died within 4-5 weeks, mice deficient in both GCase and C5aR1, and wild-type mice in which GCase and C5aR were pharmacologically inhibited, were protected from these adverse effects and consequently survived. In mice and humans, GCase deficiency was associated with strong formation of complement-activating GC-specific IgG autoantibodies, leading to complement activation and C5a generation. Subsequent C5aR1 activation controlled UDP-glucose ceramide glucosyltransferase production, thereby tipping the balance between GC formation and degradation. Thus, extensive GC storage induces complement-activating IgG autoantibodies that drive a pathway of C5a generation and C5aR1 activation that fuels a cycle of cellular GC accumulation, innate and adaptive immune cell recruitment and activation in Gaucher disease. As enzyme replacement and substrate reduction therapies are expensive and still associated with inflammation, increased risk of cancer and Parkinson disease, targeting C5aR1 may serve as a treatment option for patients with Gaucher disease and, possibly, other lysosomal storage diseases. 10.1038/nature21368
    A Combined PD-1/C5a Blockade Synergistically Protects against Lung Cancer Growth and Metastasis. Ajona Daniel,Ortiz-Espinosa Sergio,Moreno Haritz,Lozano Teresa,Pajares María J,Agorreta Jackeline,Bértolo Cristina,Lasarte Juan J,Vicent Silvestre,Hoehlig Kai,Vater Axel,Lecanda Fernando,Montuenga Luis M,Pio Ruben Cancer discovery Disruption of the programmed cell death protein 1 (PD-1) pathway with immune checkpoint inhibitors represents a major breakthrough in the treatment of non-small cell lung cancer. We hypothesized that combined inhibition of C5a/C5aR1 and PD-1 signaling may have a synergistic antitumor effect. The RMP1-14 antibody was used to block PD-1, and an L-aptamer was used to inhibit signaling of complement C5a with its receptors. Using syngeneic models of lung cancer, we demonstrate that the combination of C5a and PD-1 blockade markedly reduces tumor growth and metastasis and leads to prolonged survival. This effect is accompanied by a negative association between the frequency of CD8 T cells and myeloid-derived suppressor cells within tumors, which may result in a more complete reversal of CD8 T-cell exhaustion. Our study provides support for the clinical evaluation of anti-PD-1 and anti-C5a drugs as a novel combination therapeutic strategy for lung cancer. Using a variety of preclinical models of lung cancer, we demonstrate that the blockade of C5a results in a substantial improvement in the efficacy of anti-PD-1 antibodies against lung cancer growth and metastasis. This study provides the preclinical rationale for the combined blockade of PD-1/PD-L1 and C5a to restore antitumor immune responses, inhibit tumor cell growth, and improve outcomes of patients with lung cancer. . 10.1158/2159-8290.CD-16-1184
    Complement C5a Receptor is the Key Initiator of Neutrophil Adhesion Igniting Immune Complex-induced Arthritis. Miyabe Yoshishige,Miyabe Chie,Murooka Thomas T,Kim Edward Y,Newton Gail A,Kim Nancy D,Haribabu Bodduluri,Luscinskas Francis W,Mempel Thorsten R,Luster Andrew D Science immunology The deposition of immune complexes (IC) in tissues induces a "type III hypersensitivity" that results in tissue damage and underlies the pathogenesis of many autoimmune diseases. The neutrophil is the first immune cell recruited into sites of IC deposition and plays a critical role in shaping the overall tissue response. However, the mechanism by which IC and neutrophil infiltration into tissue is not known. Here, using intravital multiphoton joint imaging of IC-induced arthritis in live mice, we found that the complement C5a receptor (C5aR) was the key initiator of neutrophil adhesion on joint endothelium. C5a presented on joint endothelium induced β2 integrin-dependent neutrophil arrest, facilitating neutrophil spreading and transition to crawling, and subsequent leukotriene B receptor (BLT1)-mediated extravasation of the first neutrophils. The chemokine receptor CCR1 promoted neutrophil crawling on the joint endothelium while CXCR2 amplified late neutrophil recruitment and survival once in the joint. Thus, imaging arthritis has defined a new paradigm for type III hypersensitivity where C5a directly initiates neutrophil adhesion on the joint endothelium igniting inflammation. 10.1126/sciimmunol.aaj2195
    Structure of the complement C5a receptor bound to the extra-helical antagonist NDT9513727. Robertson Nathan,Rappas Mathieu,Doré Andrew S,Brown Jason,Bottegoni Giovanni,Koglin Markus,Cansfield Julie,Jazayeri Ali,Cooke Robert M,Marshall Fiona H Nature The complement system is a crucial component of the host response to infection and tissue damage. Activation of the complement cascade generates anaphylatoxins including C5a and C3a. C5a exerts a pro-inflammatory effect via the G-protein-coupled receptor C5a anaphylatoxin chemotactic receptor 1 (C5aR1, also known as CD88) that is expressed on cells of myeloid origin. Inhibitors of the complement system have long been of interest as potential drugs for the treatment of diseases such as sepsis, rheumatoid arthritis, Crohn's disease and ischaemia-reperfusion injuries. More recently, a role of C5a in neurodegenerative conditions such as Alzheimer's disease has been identified. Peptide antagonists based on the C5a ligand have progressed to phase 2 trials in psoriasis and rheumatoid arthritis; however, these compounds exhibited problems with off-target activity, production costs, potential immunogenicity and poor oral bioavailability. Several small-molecule competitive antagonists for C5aR1, such as W-54011 and NDT9513727, have been identified by C5a radioligand-binding assays. NDT9513727 is a non-peptide inverse agonist of C5aR1, and is highly selective for the primate and gerbil receptors over those of other species. Here, to study the mechanism of action of C5a antagonists, we determine the structure of a thermostabilized C5aR1 (known as C5aR1 StaR) in complex with NDT9513727. We found that the small molecule bound between transmembrane helices 3, 4 and 5, outside the helical bundle. One key interaction between the small molecule and residue Trp213 seems to determine the species selectivity of the compound. The structure demonstrates that NDT9513727 exerts its inverse-agonist activity through an extra-helical mode of action. 10.1038/nature25025
    Atypical complement receptor C5aR2 transports C5a to initiate neutrophil adhesion and inflammation. Miyabe Yoshishige,Miyabe Chie,Mani Vinidhra,Mempel Thorsten R,Luster Andrew D Science immunology Chemoattractant-induced arrest of circulating leukocytes and their subsequent diapedesis is a fundamental component of inflammation. However, how tissue-derived chemoattractants are transported into the blood vessel lumen to induce leukocyte entry into tissue is not well understood. Here, intravital microscopy in live mice has shown that the "atypical" complement C5a receptor 2 (C5aR2) and the atypical chemokine receptor 1 (ACKR1) expressed on endothelial cells were required for the transport of C5a and CXCR2 chemokine ligands, respectively, into the vessel lumen in a murine model of immune complex-induced arthritis. Transported C5a was required to initiate C5aR1-mediated neutrophil arrest, whereas transported chemokines were required to initiate CXCR2-dependent neutrophil transdendothelial migration. These findings provide new insights into how atypical chemoattractant receptors collaborate with "classical" signaling chemoattractant receptors to control distinct steps in the recruitment of neutrophils into tissue sites of inflammation. 10.1126/sciimmunol.aav5951
    Complement C5a Fosters Squamous Carcinogenesis and Limits T Cell Response to Chemotherapy. Medler Terry R,Murugan Dhaarini,Horton Wesley,Kumar Sushil,Cotechini Tiziana,Forsyth Alexandra M,Leyshock Patrick,Leitenberger Justin J,Kulesz-Martin Molly,Margolin Adam A,Werb Zena,Coussens Lisa M Cancer cell Complement is a critical component of humoral immunity implicated in cancer development; however, its biological contributions to tumorigenesis remain poorly understood. Using the K14-HPV16 transgenic mouse model of squamous carcinogenesis, we report that urokinase (uPA) macrophages regulate C3-independent release of C5a during premalignant progression, which in turn regulates protumorigenic properties of C5aR1 mast cells and macrophages, including suppression of CD8 T cell cytotoxicity. Therapeutic inhibition of C5aR1 via the peptide antagonist PMX-53 improved efficacy of paclitaxel chemotherapy associated with increased presence and cytotoxic properties of CXCR3 effector memory CD8 T cells in carcinomas, dependent on both macrophage transcriptional programming and IFNγ. Together, these data identify C5aR1-dependent signaling as an important immunomodulatory program in neoplastic tissue tractable for combinatorial cancer immunotherapy. 10.1016/j.ccell.2018.09.003
    Intracellular complement C5a/C5aR1 stabilizes β-catenin to promote colorectal tumorigenesis. Cell reports Complement is operative in not only the extracellular but also the intracellular milieu. However, little is known about the role of complement activation inside tumor cells. Here, we report that intracellular C5 is cleaved by cathepsin D (CTSD) to produce C5a in lysosomes and endosomes of colonic cancer cells. After stimulation by C5a, intracellular C5aR1 assembles a complex with KCTD5/cullin3/Roc-1 and β-catenin to promote the switch of polyubiquitination of β-catenin from K48 to K63, which enhances β-catenin stability. Genetic loss or pharmacological blockade of C5aR1 dramatically impedes colorectal tumorigenesis at least by destabilizing β-catenin. In human colorectal cancer specimens, high levels of C5aR1, C5a, and CTSD are closely correlated with elevated β-catenin levels and a poor prognosis. Importantly, intracellular C5a/C5aR1-mediated β-catenin stabilization is also observed ubiquitously in other cell types. Collectively, we identify a machinery for β-catenin activation and provide a potential target for tumor prevention and treatment. 10.1016/j.celrep.2022.110851
    The Complement C5a-C5aR1 GPCR Axis in COVID-19 Therapeutics. Woodruff Trent M,Shukla Arun K Trends in immunology The current pandemic of coronavirus disease (COVID-19) caused by SARS-CoV-2 is a significant global health challenge. A recent study by Carvelli and colleagues now demonstrates the involvement of complement C5a and its receptor C5aR1 in disease progression and suggests that blockade of the C5a-C5aR1 axis may represent a potential therapeutic strategy against COVID-19. 10.1016/j.it.2020.09.008