A Role of the Inflammasome in the Low Storage Capacity of the Abdominal Subcutaneous Adipose Tissue in Obese Adolescents.
Kursawe Romy,Dixit Vishwa D,Scherer Philipp E,Santoro Nicola,Narayan Deepak,Gordillo Ruth,Giannini Cosimo,Lopez Ximena,Pierpont Bridget,Nouws Jessica,Shulman Gerald I,Caprio Sonia
The innate immune cell sensor leucine-rich-containing family, pyrin domain containing 3 (NLRP3) inflammasome controls the activation of caspase-1, and the release of proinflammatory cytokines interleukin (IL)-1β and IL-18. The NLRP3 inflammasome is implicated in adipose tissue inflammation and the pathogenesis of insulin resistance. Herein, we tested the hypothesis that adipose tissue inflammation and NLRP3 inflammasome are linked to the downregulation of subcutaneous adipose tissue (SAT) adipogenesis/lipogenesis in obese adolescents with altered abdominal fat partitioning. We performed abdominal SAT biopsies on 58 obese adolescents and grouped them by MRI-derived visceral fat to visceral adipose tissue (VAT) plus SAT (VAT/VAT+SAT) ratio (cutoff 0.11). Adolescents with a high VAT/VAT+SAT ratio showed higher SAT macrophage infiltration and higher expression of the NLRP3 inflammasome-related genes (i.e., TLR4, NLRP3, IL1B, and CASP1). The increase in inflammation markers was paralleled by a decrease in genes related to insulin sensitivity (ADIPOQ, GLUT4, PPARG2, and SIRT1) and lipogenesis (SREBP1c, ACC, LPL, and FASN). Furthermore, SAT ceramide concentrations correlated with the expression of CASP1 and IL1B. Infiltration of macrophages and upregulation of the NLRP3 inflammasome together with the associated high ceramide content in the plasma and SAT of obese adolescents with a high VAT/VAT+SAT may contribute to the limited expansion of the subcutaneous abdominal adipose depot and the development of insulin resistance.
Gain of function mutation and inflammasome driven diseases in human and mouse models.
Cordero Mario D,Alcocer-Gómez Elísabet,Ryffel Bernhard
Journal of autoimmunity
Activation of the NLRP3 inflammasome, a multiprotein complex, leading to caspase activation with production of proinflammatory IL-1β represents a major pathway of inflammation. Recent, studies in mice and human patients uncovered several gain-of- function (GOF) mutations in inflammasome sensor proteins that allow inflammasome assembly in the absence of cognate ligands to trigger autoinflammatory syndromes. Cryopyrin-associated periodic syndromes (CAPS) are rare autoinflammatory diseases, comprising a broad disease spectrum with varying severity. CAPS are associated with GOF mutations in the NLRP3 inflammasome and activation of IL-1ß leading to episodes of fever, cutaneous, musculoskeletal, articular, ocular, and neurological symptoms. Here, we review current knowledge on different mutations leading to CAPS and related clinical syndromes. Homologous gene mutations in mice provide insights into the regulation and consequences of the activation of different inflammasomes in several autoinflammatory syndrome. In view of the critical role of IL-1ß in the pathogenesis of autoinflammatory GOF mutations such as CAPS, blockade of the action of IL-1ß is critical. Therapeutic administration of recombinant IL-1 receptor antagonists or monoclonal anti-IL-1ß antibody had a beneficial effect. Furthermore, novel inhibitors of inflammasome complex formation such as MCC950 and related compounds attenuate experimental and clinical disease. The discovery of new GOF mutants of inflammasomes leading to further insights in pathomechanisms and the development of novel inhibitors represent a great challenge.
TSPO upregulation in bipolar disorder and concomitant downregulation of mitophagic proteins and NLRP3 inflammasome activation.
Scaini Giselli,Barichello Tatiana,Fries Gabriel R,Kennon Elizabeth A,Andrews Taylor,Nix Bobby R,Zunta-Soares Giovana,Valvassori Samira S,Soares Jair C,Quevedo João
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology
Bipolar disorder (BD) is a chronic, debilitating illness with a global prevalence of up to 4.8%. The importance of understanding how dysfunctional mitochondria and mitophagy contribute to cell survival and death in BD is becoming increasingly apparent. Therefore, the purpose of this study was to evaluate the mitophagic pathway and NLRP3 inflammasome activation in peripheral blood mononuclear cells (PBMCs) of patients with BD and healthy individuals. Since 18-kDa translocator protein (TSPO) plays an important role in regulating mitochondrial function and since TSPO itself impairs cellular mitophagy, we also investigated the changes in the TSPO-related pathway. Our results showed that patients with BD had lower levels of Parkin, p62/SQSTM1 and LC3A and an upregulation of TSPO pathway proteins (TSPO and VDAC), both in terms of mRNA and protein levels. Additionally, we found a negative correlation between mitophagy-related proteins and TSPO levels, while VDAC correlated negatively with p62/SQSTM1 and LC3 protein levels. Moreover, we found that the gene expression levels of the NLRP3-related proteins NLRP3, ASC, and pro-casp1 were upregulated in BD patients, followed by an increase in caspase-1 activity as well as IL-1β and IL-18 levels. As expected, there was a strong positive correlation between NLRP3-related inflammasome activation and TSPO-related proteins. The data reported here suggest that TSPO-VDAC complex upregulation in BD patients, the simultaneous downregulation of mitophagic proteins and NLRP3 inflammasome activation could lead to an accumulation of dysfunctional mitochondria, resulting in inflammation and apoptosis. In summary, the findings of this study provide novel evidence that mitochondrial dysfunction measured in peripheral blood is associated with BD.
Ablation of Neuropilin 1 in Myeloid Cells Exacerbates High-Fat Diet-Induced Insulin Resistance Through Nlrp3 Inflammasome In Vivo.
Dai Xiaoyan,Okon Imoh,Liu Zhaoyu,Bedarida Tatiana,Wang Qilong,Ramprasath Tharmarajan,Zhang Miao,Song Ping,Zou Ming-Hui
Neuropilin 1 (Nrp1), a coreceptor for class 3 semaphorins and growth factors, is highly expressed in vascular cells and myeloid cells, including macrophages. Unlike well-characterized proangiogenic functions of endothelial cell Nrp1, the contributions of macrophage Nrp1 within the context of metabolic dysfunction remain to be established. The aim of this study was to determine the contributions of macrophage Nrp1 in high-fat diet (HFD)-instigated insulin resistance in vivo. Insulin sensitivity and Nlrp3 inflammasome activation were monitored in wild-type (WT) and myeloid cell-specific Nrp1 knockout (Nrp1) mice fed an HFD (60% kcal) for 16 weeks. HFD-fed mice exhibited insulin resistance with reduced levels of Nrp1 in macrophages compared with chow-fed mice. Further, HFD-fed Nrp1 mice displayed accentuated insulin resistance, enhanced systemic inflammation, and dramatically increased Nlrp3 inflammasome priming and activation. Importantly, knockout of Nlrp3 ablated HFD-induced insulin resistance and inflammation in Nrp1 mice, indicating that Nrp1 reduction in macrophages instigates insulin resistance by increasing macrophage Nlrp3 inflammasome activation. Mechanistically, Nrp1 deletion activates the nuclear factor-κB pathway, which in turn accentuates the priming of Nlrp3, promotes Nlrp3-ASC inflammasome assembly, and results in the activation of Nlrp3. We conclude that the HFD-instigated Nrp1 reduction in macrophages exacerbates insulin resistance by promoting Nlrp3 inflammasome priming and activation.
Psychological Stress Activates the Inflammasome via Release of Adenosine Triphosphate and Stimulation of the Purinergic Type 2X7 Receptor.
Iwata Masaaki,Ota Kristie T,Li Xiao-Yuan,Sakaue Fumika,Li Nanxin,Dutheil Sophie,Banasr Mounira,Duric Vanja,Yamanashi Takehiko,Kaneko Koichi,Rasmussen Kurt,Glasebrook Andrew,Koester Anja,Song Dekun,Jones Kenneth A,Zorn Stevin,Smagin Gennady,Duman Ronald S
BACKGROUND:The mechanisms underlying stress-induced inflammation that contribute to major depressive disorder are unknown. We examine the role of the adenosine triphosphate (ATP)/purinergic type 2X7 receptor (P2X7R) pathway and the NLRP3 (nucleotide-binding, leucine-rich repeat, pyrin domain containing 3) inflammasome in interleukin (IL)-1β and depressive behavioral responses to stress. METHODS:The influence of acute restraint stress on extracellular ATP, glutamate, IL-1β, and tumor necrosis factor alpha in hippocampus was determined by microdialysis, and the influence of acute restraint stress on the NLRP3 inflammasome was determined by western blot analysis. The influence of P2X7R antagonist administration on IL-1β and tumor necrosis factor alpha and on anxiety and depressive behaviors was determined in the chronic unpredictable stress rodent model. The role of the NLRP3 inflammasome was determined by analysis of Nlrp3 null mice. RESULTS:Acute restraint stress rapidly increased extracellular ATP, an endogenous agonist of P2X7R; the inflammatory cytokine IL-1β; and the active form of the NLRP3 inflammasome in the hippocampus. Administration of a P2X7R antagonist completely blocked the release of IL-1β and tumor necrosis factor alpha, another stress-induced cytokine, and activated NLRP3. Moreover, P2X7R antagonist administration reversed the anhedonic and anxiety behaviors caused by chronic unpredictable stress exposure, and deletion of the Nlrp3 gene rendered mice resistant to development of depressive behaviors caused by chronic unpredictable stress. CONCLUSIONS:These findings demonstrate that psychological "stress" is sensed by the innate immune system in the brain via the ATP/P2X7R-NLRP3 inflammasome cascade, and they identify novel therapeutic targets for the treatment of stress-related mood disorders and comorbid illnesses.
lincRNA-Cox2 regulates NLRP3 inflammasome and autophagy mediated neuroinflammation.
Xue Zhenyi,Zhang Zimu,Liu Hongkun,Li Wen,Guo Xiangdong,Zhang Zhihui,Liu Ying,Jia Long,Li Yan,Ren Yinghui,Yang Hongwei,Zhang Lijuan,Zhang Qi,Da Yurong,Hao Junwei,Yao Zhi,Zhang Rongxin
Cell death and differentiation
Inflammasome activation plays key roles in host defense, but also contributes to the pathogenesis of auto-inflammatory, and neurodegenerative diseases. As autophagy is connected with both the innate and adaptive immune systems, autophagic dysfunction is also closely related to inflammation, infection, and neurodegeneration. Here we identify that lincRNA-Cox2, previously known as a mediator of both the activation and repression of immune genes expression in innate immune cells, could bind NF-κB p65 and promote its nuclear translocation and transcription, modulating the expression of inflammasome sensor NLRP3 and adaptor ASC. Knockdown of lincRNA-Cox2 inhibited the inflammasome activation and prevented the lincRNA-Cox2-triggered caspase-1 activation, leading to decreased IL-1β secretion and weakened TIR-domain-containing adapter-inducing interferon-β (TRIF) cleavage, thereby enhancing TRIF-mediated autophagy. Elucidation of the link between lincRNA-Cox2 and the inflammasome-autophagy crosstalk in macrophage and microglia reveals a role for lncRNAs in activation of NLRP3 inflammasome and autophagy, and provides new opportunities for therapeutic intervention in neuroinflammation-dependent diseases.
MPTP-driven NLRP3 inflammasome activation in microglia plays a central role in dopaminergic neurodegeneration.
Lee Eunju,Hwang Inhwa,Park Sangjun,Hong Sujeong,Hwang Boreum,Cho Yoeseph,Son Junghyun,Yu Je-Wook
Cell death and differentiation
Parkinson's disease (PD) is a progressive neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra (SN) and the reduction of dopamine levels in the striatum. Although details of the molecular mechanisms underlying dopaminergic neuronal death in PD remain unclear, neuroinflammation is also considered a potent mediator in the pathogenesis and progression of PD. In the present study, we present evidences that microglial NLRP3 inflammasome activation is critical for dopaminergic neuronal loss and the subsequent motor deficits in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. Specifically, NLRP3 deficiency significantly reduces motor dysfunctions and dopaminergic neurodegeneration of MPTP-treated mice. Furthermore, NLRP3 deficiency abolishes MPTP-induced microglial recruitment, interleukin-1β production and caspase-1 activation in the SN of mouse brain. In primary microglia and mixed glial cell cultures, MPTP/ATP treatment promotes the robust assembly and activation of the NLRP3 inflammasome via producing mitochondrial reactive oxygen species. Consistently, 1-methyl-4-phenyl-pyridinium (MPP) induces NLRP3 inflammasome activation in the presence of ATP or nigericin treatment in mouse bone-marrow-derived macrophages. These findings reveal a novel priming role of neurotoxin MPTP or MPP for NLRP3 activation. Subsequently, NLRP3 inflammasome-active microglia induces profound neuronal death in a microglia-neuron co-culture model. Furthermore, Cx3Cr1-based microglia-specific expression of an active NLRP3 mutant greatly exacerbates motor deficits and dopaminergic neuronal loss of MPTP-treated mice. Taken together, our results indicate that microglial NLRP3 inflammasome activation plays a pivotal role in the MPTP-induced neurodegeneration in PD.
NLRP3 inflammasome activation results in hepatocyte pyroptosis, liver inflammation, and fibrosis in mice.
Wree Alexander,Eguchi Akiko,McGeough Matthew D,Pena Carla A,Johnson Casey D,Canbay Ali,Hoffman Hal M,Feldstein Ariel E
Hepatology (Baltimore, Md.)
UNLABELLED:Inflammasome activation plays a central role in the development of drug-induced and obesity-associated liver disease. However, the sources and mechanisms of inflammasome-mediated liver damage remain poorly understood. Our aim was to investigate the effect of NLRP3 inflammasome activation on the liver using novel mouse models. We generated global and myeloid cell-specific conditional mutant Nlrp3 knock-in mice expressing the D301N Nlrp3 mutation (ortholog of D303N in human NLRP3), resulting in a hyperactive NLRP3. To study the presence and significance of NLRP3-initiated pyroptotic cell death, we separated hepatocytes from nonparenchymal cells and developed a novel flow-cytometry-based (fluorescence-activated cell sorting; FACS) strategy to detect and quantify pyroptosis in vivo based on detection of active caspase 1 (Casp1)- and propidium iodide (PI)-positive cells. Liver inflammation was quantified histologically by FACS and gene expression analysis. Liver fibrosis was assessed by Sirius Red staining and quantitative polymerase chain reaction for markers of hepatic stellate cell (HSC) activation. NLRP3 activation resulted in shortened survival, poor growth, and severe liver inflammation; characterized by neutrophilic infiltration and HSC activation with collagen deposition in the liver. These changes were partially attenuated by treatment with anakinra, an interleukin-1 receptor antagonist. Notably, hepatocytes from global Nlrp3-mutant mice showed marked hepatocyte pyroptotic cell death, with more than a 5-fold increase in active Casp1/PI double-positive cells. Myeloid cell-restricted mutant NLRP3 activation resulted in a less-severe liver phenotype in the absence of detectable pyroptotic hepatocyte cell death. CONCLUSIONS:Our data demonstrate that global and, to a lesser extent, myeloid-specific NLRP3 inflammasome activation results in severe liver inflammation and fibrosis while identifying hepatocyte pyroptotic cell death as a novel mechanism of NLRP3-mediated liver damage.
NLRP3 inflammasome activation drives tau pathology.
Ising Christina,Venegas Carmen,Zhang Shuangshuang,Scheiblich Hannah,Schmidt Susanne V,Vieira-Saecker Ana,Schwartz Stephanie,Albasset Shadi,McManus Róisín M,Tejera Dario,Griep Angelika,Santarelli Francesco,Brosseron Frederic,Opitz Sabine,Stunden James,Merten Maximilian,Kayed Rakez,Golenbock Douglas T,Blum David,Latz Eicke,Buée Luc,Heneka Michael T
Alzheimer's disease is characterized by the accumulation of amyloid-beta in plaques, aggregation of hyperphosphorylated tau in neurofibrillary tangles and neuroinflammation, together resulting in neurodegeneration and cognitive decline. The NLRP3 inflammasome assembles inside of microglia on activation, leading to increased cleavage and activity of caspase-1 and downstream interleukin-1β release. Although the NLRP3 inflammasome has been shown to be essential for the development and progression of amyloid-beta pathology in mice, the precise effect on tau pathology remains unknown. Here we show that loss of NLRP3 inflammasome function reduced tau hyperphosphorylation and aggregation by regulating tau kinases and phosphatases. Tau activated the NLRP3 inflammasome and intracerebral injection of fibrillar amyloid-beta-containing brain homogenates induced tau pathology in an NLRP3-dependent manner. These data identify an important role of microglia and NLRP3 inflammasome activation in the pathogenesis of tauopathies and support the amyloid-cascade hypothesis in Alzheimer's disease, demonstrating that neurofibrillary tangles develop downstream of amyloid-beta-induced microglial activation.
DDX3X acts as a live-or-die checkpoint in stressed cells by regulating NLRP3 inflammasome.
Samir Parimal,Kesavardhana Sannula,Patmore Deanna M,Gingras Sebastien,Malireddi R K Subbarao,Karki Rajendra,Guy Clifford S,Briard Benoit,Place David E,Bhattacharya Anannya,Sharma Bhesh Raj,Nourse Amanda,King Sharon V,Pitre Aaron,Burton Amanda R,Pelletier Stephane,Gilbertson Richard J,Kanneganti Thirumala-Devi
The cellular stress response has a vital role in regulating homeostasis by modulating cell survival and death. Stress granules are cytoplasmic compartments that enable cells to survive various stressors. Defects in the assembly and disassembly of stress granules are linked to neurodegenerative diseases, aberrant antiviral responses and cancer. Inflammasomes are multi-protein heteromeric complexes that sense molecular patterns that are associated with damage or intracellular pathogens, and assemble into cytosolic compartments known as ASC specks to facilitate the activation of caspase-1. Activation of inflammasomes induces the secretion of interleukin (IL)-1β and IL-18 and drives cell fate towards pyroptosis-a form of programmed inflammatory cell death that has major roles in health and disease. Although both stress granules and inflammasomes can be triggered by the sensing of cellular stress, they drive contrasting cell-fate decisions. The crosstalk between stress granules and inflammasomes and how this informs cell fate has not been well-studied. Here we show that the induction of stress granules specifically inhibits NLRP3 inflammasome activation, ASC speck formation and pyroptosis. The stress granule protein DDX3X interacts with NLRP3 to drive inflammasome activation. Assembly of stress granules leads to the sequestration of DDX3X, and thereby the inhibition of NLRP3 inflammasome activation. Stress granules and the NLRP3 inflammasome compete for DDX3X molecules to coordinate the activation of innate responses and subsequent cell-fate decisions under stress conditions. Induction of stress granules or loss of DDX3X in the myeloid compartment leads to a decrease in the production of inflammasome-dependent cytokines in vivo. Our findings suggest that macrophages use the availability of DDX3X to interpret stress signals and choose between pro-survival stress granules and pyroptotic ASC specks. Together, our data demonstrate the role of DDX3X in driving NLRP3 inflammasome and stress granule assembly, and suggest a rheostat-like mechanistic paradigm for regulating live-or-die cell-fate decisions under stress conditions.
NLRP3 Phosphorylation Is an Essential Priming Event for Inflammasome Activation.
Song Nan,Liu Zhao-Shan,Xue Wen,Bai Zhao-Fang,Wang Qian-Yi,Dai Jiang,Liu Xin,Huang Yi-Jiao,Cai Hong,Zhan Xiao-Yan,Han Qiu-Ying,Wang Hongxia,Chen Yuan,Li Hui-Yan,Li Ai-Ling,Zhang Xue-Min,Zhou Tao,Li Tao
Many infections and stress signals can rapidly activate the NLRP3 inflammasome to elicit robust inflammatory responses. This activation requires a priming step, which is thought to be mainly for upregulating NLRP3 transcription. However, recent studies report that the NLRP3 inflammasome can be activated independently of transcription, suggesting that the priming process has unknown essential regulatory steps. Here, we report that JNK1-mediated NLRP3 phosphorylation at S194 is a critical priming event and is essential for NLRP3 inflammasome activation. We show that NLRP3 inflammasome activation is disrupted in NLRP3-S194A knockin mice. JNK1-mediated NLRP3 S194 phosphorylation is critical for NLRP3 deubiquitination and facilitates its self-association and the subsequent inflammasome assembly. Importantly, we demonstrate that blocking S194 phosphorylation prevents NLRP3 inflammasome activation in cryopyrin-associated periodic syndromes (CAPS). Thus, our study reveals a key priming molecular event that is a prerequisite for NLRP3 inflammasome activation. Inhibiting NLRP3 phosphorylation could be an effective treatment for NLRP3-related diseases.
Mechanism and Regulation of NLRP3 Inflammasome Activation.
He Yuan,Hara Hideki,Núñez Gabriel
Trends in biochemical sciences
Members of the nucleotide-binding domain and leucine-rich repeat (LRR)-containing (NLR) family and the pyrin and HIN domain (PYHIN) family can form multiprotein complexes termed 'inflammasomes'. The biochemical function of inflammasomes is to activate caspase-1, which leads to the maturation of interleukin 1 beta (IL-1β) and IL-18 and the induction of pyroptosis, a form of cell death. Unlike other inflammasomes, the NLRP3 inflammasome can be activated by diverse stimuli. The importance of the NLRP3 inflammasome in immunity and human diseases has been well documented, but the mechanism and regulation of its activation remain unclear. In this review we summarize current understanding of the mechanism and regulation of NLRP3 inflammasome activation as well as recent advances in the noncanonical and alternative inflammasome pathways.