Lipid droplet-mediated danger signaling balances Trem2+ macrophage induction and NLRP3 inflammasome activation in NASH
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ABSTRACT:
PROVIDER: PRJNA962145 | ENA |
REPOSITORIES: ENA
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Project description:Macrophages are exquisitely capable of sensing danger-associated molecular patterns (DAMPs) and orchestrating inflammatory response during tissue injury. Nonalcoholic steatohepatitis (NASH) represents an advanced stage of metabolic fatty liver disease that increases the risk for cirrhosis and liver cancer. Pathogenic mechanisms of NASH center on hepatocyte injury and the ensuing immune response within the liver microenvironment. However, the nature of DAMPs released by injured hepatocytes and how they shape the liver immune milieu remain largely unknown. Here we show that lipid droplets (LDs) released by injured fatty hepatocytes provide a potent signal that triggers monocyte infiltration and maturation into Trem2+ macrophages, recently described as NASH-associated macrophages (NAMs) or lipid- associated macrophages. LD treatment exacerbated liver injury in mice with diet-induced NASH. We identified Membrane spanning 4-domains a7 (Ms4a7) as a NAM-specific pathogenic factor that was strongly induced in mouse and human NASH. Ms4a7 inactivation ameliorated key aspects of diet-induced NASH pathologies in mice. At the mechanistic level, Ms4a7 physically interacts with NLR family pyrin domain containing 3 (NLRP3) and is required for endosomal NLRP3 inflammasome activation. These findings illustrate a crucial role of Ms4a7 in driving pro-inflammatory signaling in NASH liver. Surprisingly, LD treatments attenuated Ms4a7 expression and NLRP3 inflammasome activation in cultured macrophages. As such, LDs serve as a DAMP signal that balances the induction of Trem2+ macrophages and NLRP3 inflammasome activation in NASH liver
2024-04-26 | GSE230700 | GEO
Project description:Inflammasome, activated by pathogen-derived and host-derived danger signals, constitutes a multimolecular signaling complex that serves as a platform for caspase-1 (CASP1) activation and interleukin-1beta (IL1B) maturation. The activation of NLRP3 inflammasome requires two-step signals. The first “priming” signal (Signal 1) enhances gene expression of inflammasome components. The second “activation” signal (Signal 2) promotes the assembly of inflammasome components. Deregulated activation of NLRP3 inflammasome contributes to the pathological processes of Alzheimer’s disease (AD) and multiple sclerosis (MS). However, at present, the precise mechanism regulating NLRP3 inflammasome activation and deactivation remains largely unknown. By genome-wide gene expression profiling, we studied the molecular network of NLRP3 inflammasome activation-responsive genes in a human monocyte cell line THP-1 sequentially given two-step signals. We identified the set of 83 NLRP3 inflammasome activation-responsive genes. Among them, we found the NR4A nuclear receptor family NR4A1, NR4A2, and NR4A3, the EGR family EGR1, EGR2, and EGR3, the IkappaB family NFKBIZ, NFKBID, and NFKBIA as a key group of the genes that possibly constitute a negative feedback loop for shutting down inflammation following NLRP3 inflammasome activation. By molecular network analysis, we identified a complex network of NLRP3 inflammasome activation-responsive genes involved in cellular development and death, and immune and inflammatory responses, where transcription factors AP-1, NR4A, and EGR serve as a hub. Thus, NLRP3 inflammasome activation-responsive genes constitute the molecular network composed of a set of negative feedback regulators for prompt resolution of inflammation. To load the Signal 1 (S1), THP-1 cells were incubated for 3 hours in the culture medium with or without inclusion of 0.2 microgram/ml lipopolysaccharide (LPS). To load the Signal 2 (S2), they were incubated further for 2 hours in the culture medium with inclusion of 10 microM nigericin sodium salt dissolved in ethanol or the equal v/v% concentration of ethanol (vehicle), followed by processing for microarray analysis on Human Gene 1.0 ST Array (Affymetrix).
2014-07-01 | E-GEOD-58959 | biostudies-arrayexpress
Project description:The NLRP3 inflammasome is a multi-protein complex that triggers the activation of the inflammatory protein caspase-1 and the maturation of the cytokine IL-1 in response to microbes and other danger signals in host cells. Here, we sought a deeper understanding of how the NLRP3 inflammasome is regulated. We found that inflammasome activation induced the Src family kinase Lyn to phosphorylate NLRP3 at Tyr918, and that this phosphorylation of NLRP3 correlated with a subsequent increase in its ubiquitination, which facilitated its proteasome-mediated degradation. NLRP3 tyrosine phosphorylation and ubiquitination was abrogated in Lyn-deficient macrophages, which produced increased amounts of IL-1. Furthermore, mice lacking Lyn were highly susceptible to LPS-induced septic shock in an NLRP3-dependent manner. Our data demonstrate that Lyn-mediated tyrosine phosphorylation of NLRP3 is a prerequisite for its ubiquitination, thus dampening NLRP3 inflammasome activity.
2022-05-19 | PXD028582 | Pride
Project description:Short chain fatty acids (SCFAs) are immunomodulatory compounds produced by the microbiome through fermentation of dietary fibre. Although they are generally considered beneficial for gut health, patients suffering from inflammatory bowel disease (IBD) have shown poor tolerance to fibre-rich diets, suggesting that SCFAs may have contrary effects under inflammatory conditions. To investigate this, we examined the effect of SCFAs on human macrophages in the presence of toll-like receptor agonists. In contrast to their anti-inflammatory effects under steady state conditions, we observed that the SCFAs butyrate and propionate triggered the activation of the NLRP3 inflammasome when added in conjunction with TLR agonists. Mechanistically, butyrate and propionate activated NLRP3 by inhibiting HDACs 1-3 and 10, leading to an uneven distribution of histone hyperacetylation that resulted in alterations in the transcriptome. Specifically, there was a lack of hyperacetylation at the loci of the CFLAR and IL10 genes, two important inhibitors of NLRP3 inflammasome activation. The concurrent loss of transcription and protein expression of cFLIP and IL-10 enabled caspase-8-dependent NLRP3-inflammasome activation. SCFA-driven NLRP3 activation did not require potassium efflux and did not result in cell death but rather triggered hyperactivation and IL-1b release. Our findings demonstrate that butyrate and propionate are bacterially-derived, viability-dependent danger signals (vita-PAMPs) that regulate NLRP3 inflammasome activation through epigenetic modulation of the inflammatory response.
2024-08-19 | GSE248578 | GEO
Project description:Short chain fatty acids (SCFAs) are immunomodulatory compounds produced by the microbiome through fermentation of dietary fibre. Although they are generally considered beneficial for gut health, patients suffering from inflammatory bowel disease (IBD) have shown poor tolerance to fibre-rich diets, suggesting that SCFAs may have contrary effects under inflammatory conditions. To investigate this, we examined the effect of SCFAs on human macrophages in the presence of toll-like receptor agonists. In contrast to their anti-inflammatory effects under steady state conditions, we observed that the SCFAs butyrate and propionate triggered the activation of the NLRP3 inflammasome when added in conjunction with TLR agonists. Mechanistically, butyrate and propionate activated NLRP3 by inhibiting HDACs 1-3 and 10, leading to an uneven distribution of histone hyperacetylation that resulted in alterations in the transcriptome. Specifically, there was a lack of hyperacetylation at the loci of the CFLAR and IL10 genes, two important inhibitors of NLRP3 inflammasome activation. The concurrent loss of transcription and protein expression of cFLIP and IL-10 enabled caspase-8-dependent NLRP3-inflammasome activation. SCFA-driven NLRP3 activation did not require potassium efflux and did not result in cell death but rather triggered hyperactivation and IL-1b release. Our findings demonstrate that butyrate and propionate are bacterially-derived, viability-dependent danger signals (vita-PAMPs) that regulate NLRP3 inflammasome activation through epigenetic modulation of the inflammatory response.
2024-08-19 | GSE248577 | GEO
Project description:NLRP3 inflammasome assembles in response to stress or danger signals and leads to unconventional secretion of proinflammatory IL-1. FADD is an NLRP3 inflammasome component. Here we found that classical NLRP3 inflammasome activation in human monocytes/macrophages induced FADD secretion, which required potassium efflux, functional NLRP3 sensor, ASC adaptor and caspase-1 scaffold molecule. FADD is a leaderless protein unconventionally secreted through plasma membrane-derived microvesicles. Blood-derived monocytes from rheumatoid arthritis (RA) patients secreted more FADD following NLRP3 inflammasome activation than those from healthy donors, and we found increased levels of FADD in the sera (ESPOIR cohort) and synovial fluids from RA patients. Levels of synovial FADD correlated with the inflammatory status of the joint. These data reveal that FADD secretion occurs during inflammatory disease in vivo.
2019-02-28 | PXD008168 | Pride
Project description:Inflammasome, activated by pathogen-derived and host-derived danger signals, constitutes a multimolecular signaling complex that serves as a platform for caspase-1 (CASP1) activation and interleukin-1beta (IL1B) maturation. The activation of NLRP3 inflammasome requires two-step signals. The first “priming” signal (Signal 1) enhances gene expression of inflammasome components. The second “activation” signal (Signal 2) promotes the assembly of inflammasome components. Deregulated activation of NLRP3 inflammasome contributes to the pathological processes of Alzheimer’s disease (AD) and multiple sclerosis (MS). However, at present, the precise mechanism regulating NLRP3 inflammasome activation and deactivation remains largely unknown. By genome-wide gene expression profiling, we studied the molecular network of NLRP3 inflammasome activation-responsive genes in a human monocyte cell line THP-1 sequentially given two-step signals. We identified the set of 83 NLRP3 inflammasome activation-responsive genes. Among them, we found the NR4A nuclear receptor family NR4A1, NR4A2, and NR4A3, the EGR family EGR1, EGR2, and EGR3, the IkappaB family NFKBIZ, NFKBID, and NFKBIA as a key group of the genes that possibly constitute a negative feedback loop for shutting down inflammation following NLRP3 inflammasome activation. By molecular network analysis, we identified a complex network of NLRP3 inflammasome activation-responsive genes involved in cellular development and death, and immune and inflammatory responses, where transcription factors AP-1, NR4A, and EGR serve as a hub. Thus, NLRP3 inflammasome activation-responsive genes constitute the molecular network composed of a set of negative feedback regulators for prompt resolution of inflammation.
2014-07-01 | GSE58959 | GEO
Project description:The NLRP3 inflammasome is dysregulated in autoinflammatory disorders caused by inherited mutations and contributes to the pathogenesis of several chronic inflammatory diseases. In this study, we discovered that disulfiram, a safe FDA-approved drug, specifically inhibits the NLRP3 inflammasome, but not the NLRC4 or AIM2 inflammasomes. Disulfiram suppresses caspase-1 activation, ASC speck formation, and pyroptosis induced by several stimuli that activate NLRP3. Mechanistically, NLRP3 is palmitoylated at cysteine 126, a modification required for its localization to the trans-Golgi network and inflammasome activation which was inhibited by disulfiram. Administration of disulfiram to animals inhibited the NLRP3, but not the NLRC4 inflammasome in vivo. Our study uncovers a mechanism by which disulfiram targets NLRP3 and provides a rationale for using a safe FDA-approved drug for the treatment of NLRP3-associated inflammatory diseases.
2024-07-25 | PXD054126 | Pride
Project description:Trimethyltin (TMT) and triethyltin (TET) are two tri-organotin compounds, a group of substances reported to affect mitochondria function. These compounds were also found to activate the NLRP3 inflammasome, an inflammatory cascade that occurs in myeloid cells when primed with a Toll-like receptor ligand (i.e. LPS) followed by activation by an exogenous or endogenous danger signal. The inflammasome is a very tightly regulated mechanism, with several miRNAs playing an important role. To determine differential miRNA changes between TMT and TET induced inflammasome activation, miRNA expression profiles were evaluated in LPS-primed murine bone marrow derived macrophages (BMDMs) exposed to TMT or TET as compared to saline. mRNA expression arrays were also performed and analyzed to identify miRNA target genes in order to elucidate the key mechanism(s) by which TMT and TET activate the NLRP3 inflammasome pathway. These studies will help us understand the inflammasome regulation in macrophages by organotin.
2021-05-05 | GSE155127 | GEO
Project description:Trimethyltin (TMT) and triethyltin (TET) are two tri-organotin compounds, a group of substances reported to affect mitochondria function. These compounds were also found to activate the NLRP3 inflammasome, an inflammatory cascade that occurs in myeloid cells when primed with a Toll-like receptor ligand (i.e. LPS) followed by activation by an exogenous or endogenous danger signal. The inflammasome is a very tightly regulated mechanism, with several miRNAs playing an important role. To determine differential miRNA changes between TMT and TET induced inflammasome activation, miRNA expression profiles were evaluated in LPS-primed murine bone marrow derived macrophages (BMDMs) exposed to TMT or TET as compared to saline. mRNA expression arrays were also performed and analyzed to identify miRNA target genes in order to elucidate the key mechanism(s) by which TMT and TET activate the NLRP3 inflammasome pathway. These studies will help us understand the inflammasome regulation in macrophages by organotin.
2021-05-05 | GSE155126 | GEO