Project description:The immune system may respond to engineered nanomaterials (ENM) through inflammatory reactions. The NLRP3 inflammasome responds to a wide range of ENM, and its activation is associated with various inflammatory diseases. The objective of the study was to compare the effects of gold ENM of different shapes on NLRP3 inflammasome activation and related signalling pathways. Differentiated THP-1 cells (wildtype, ASC- or NLRP3-deficient), were exposed to PEGylated gold nanorods, nanostars, and nanospheres. Exposed cells were subjected to gene expression analysis. Nanorods, but not nanostars or nanospheres, showed NLRP3 inflammasome activation. ASC- or NLRP3-deficient cells did not show this effect. Gold nanorod-induced NLRP3 inflammasome activation was accompanied by downregulated sterol/cholesterol biosynthesis, oxidative phosphorylation, and purinergic receptor signalling. In conclusion, the shape and surface chemistry of gold nanoparticles determine NLRP3 inflammasome activation.
Project description:This experiment was performed to analyze the contribution of NLRP3 inflammasome activation to age-related changes in hippocampal RNA. The hypothesis was that decreased inflammasome activation would reduce hippocampal inflammation. Results indicate that inflammasome knockout animals are protected from age-related changes in hippocampal gene expression Gene expression profiles of young (1 month) and old (21-23 month) wild type, CIAS -/- and ASC -/- mouse hippocampal tissue were compared. Total mRNA was extracted using Trizol.
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).
Project description:This experiment was performed to analyze the contribution of NLRP3 inflammasome activation to age-related changes in hippocampal RNA. The hypothesis was that decreased inflammasome activation would reduce hippocampal inflammation. Results indicate that inflammasome knockout animals are protected from age-related changes in hippocampal gene expression
Project description:The innate immune system recognizes nucleic acids as a signature of microbial infection and initiates host-protective responses, including the production of type I IFN and proinflammatory cytokines. Z-DNA binding protein 1 (ZBP1, also known as DLM-1 or DAI) was previously identified as a dsDNA binding protein, triggering DNA-mediated activation of innate immune responses. However, mice or cells lacking ZBP1 produce normal levels of type I IFN in response to dsDNA. Therefore, the classification of ZBP1 as a true DNA sensor remains to be resolved. Here, we report that the single stranded RNA virus, influenza A virus (IAV) is a trigger of the cytosolic sensor ZBP1. Sensing of IAV infection by ZBP1 engages a novel NLRP3 inflammasome pathway that is not defined by the conventions of the canonical and non-canonical NLRP3 inflammasome pathways. Surprisingly, IAV-induced cell death was not prevented by the absence of the NLRP3 inflammasome. Instead, we identified parallel contributions from pyroptosis, necroptosis and apoptosis in the execution of ZBP1-dependent cell death, mediated by the kinase RIPK3. Overall, the ability of ZBP1 to sense IAV infection signifies a point of divergence for IAV-induced programmed cell death pathways and inflammasome activation. We used microarrays to explore the gene expression profiles differentially expressed in influenza-infected bone marrow derived macrophages (BMDM) isolated from Ifnar1-/- and wild-type mice.
Project description:The NLRP3 inflammasome is linked to sterile and pathogen-dependent inflammation, and its dysregulation underlies many chronic diseases. Mitochondria have been implicated as regulators of NLRP3 inflammasome through multiple mechanisms including generation of mitochondrial ROS. Here we report that mitochondrial electron transport chain (ETC) complexes I, II, III and V inhibitors all prevent NLRP3 inflammasome activation. Ectopic expression of Saccharomyces cerevisiae NADH dehydrogenase (NDI1) or Ciona intestinalis alternative oxidase (AOX), which can respectively complement the functional loss of mitochondrial complex I or III, without generation of ROS, rescued NLRP3 inflammasome activation in the absence of endogenous mitochondrial complex I or complex III function. Metabolomics revealed phosphocreatine (PCr), which can sustain ATP levels, as a common metabolite that is diminished by mitochondrial ETC inhibitors. PCr depletion decreased ATP levels and NLRP3 inflammasome activation. Thus, mitochondrial ETC sustains NLRP3 inflammasome activation through PCr-dependent generation of ATP but a ROS independent mechanism.
Project description:The activation of the NLRP3 inflammasome is spatiotemporally orchestrated by various organelles, but the precise roles of lysosomes are still unclear. Here we show the vital role of the Ragulator complex, a lysosomal protein, in NLRP3 inflammasome activation. Deficiency of Lamtor1, an essential component of the Ragulator complex, abrogated NLRP3 inflammasome activation in murine macrophage and human monocytic cells. Myeloid-specific Lamtor1-deficient mice showed remarkable attenuation of the severity of NLRP3-associated inflammatory diseases, including LPS-induced sepsis, alum-induced peritonitis, and monosodium urate (MSU)-induced arthritis. Mechanistically, Lamtor1 interacted with histone deacetylase 6 (HDAC6) during NLRP3 inflammasome activation, and this interaction augmented the interaction between the Ragulator complex and NLRP3. Lack of HDAC6 attenuated the interaction between Lamtor1 and NLRP3, resulting in insufficient NLRP3 inflammasome activation. Furthermore, DL-all-rac-α-tocopherol inhibited Lamtor1–HDAC6 interaction, resulting in diminished NLRP3 inflammasome activation. DL-all-rac-α-tocopherol alleviated acute gouty arthritis and MSU-induced peritonitis. Our results provide insight into the role of lysosomes in providing a platform for the activation of NLRP3 inflammasomes by the Ragulator complex.
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.
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.