Leptin Induces Apoptotic and Pyroptotic Cell Death via NLRP3 Inflammasome Activation in Rat Hepatocytes.
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ABSTRACT:
SUBMITTER: Baral A
PROVIDER: S-EPMC8622994 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Echovirus 11 (ECHO 11) is a positive-strand RNA virus belonging to the genus Enterovirus of the family Picornaviridae. ECHO 11 infections can cause severe inflammatory illnesses in neonates, including severe acute hepatitis with coagulopathy. The activation of NLRP3 inflammasome is important for host defense against invading viruses, which also contributes to viral pathogenicity. However, whether and how ECHO 11 induces NLRP3 inflammasome activation remains unclear. In this study, we isolated a clinical strain of ECHO 11 from stools of an ECHO 11-infected newborn patient with necrotizing hepatitis. This virus shared 99.95% sequence identity with the previously published ECHO 11 sequence. The clinically isolated ECHO 11 can efficiently infect liver cells and strongly induces inflammation. Moreover, we showed that ECHO 11 induced IL-1β secretion and pyroptosis in cells and mouse bone marrow-derived macrophages (BMDMs). Furthermore, ECHO 11 infection triggered NLRP3 inflammasome activation, as evidenced by cleavages of GSDMD, pro-IL-1β and pro-caspase-1, and the release of LDH. ECHO 11 2B protein was required for NLRP3 inflammasome activation via interacting with NLRP3 to facilitate the inflammasome complex assembly. In vivo, expression of ECHO 11 2B also activated NLRP3 inflammasome in the murine liver. Besides, 2Bs of multiple EVs can also interact with NLRP3 and induce NLRP3 inflammasome activation. Together, our findings demonstrate a mechanism by which ECHO 11 induces inflammatory responses by activating NLRP3 inflammasome, providing novel insights into the pathogenesis of ECHO 11 infection.
| S-EPMC9455886 | biostudies-literature
Project description:The incidence of chronic liver disease is constantly increasing, owing to the obesity epidemic. However, the causes and mechanisms of inflammation-mediated liver damage remain poorly understood. Endoplasmic reticulum (ER) stress is an initiator of cell death and inflammatory mechanisms. Although obesity induces ER stress, the interplay between hepatic ER stress, NLRP3 inflammasome activation and hepatocyte death signaling has not yet been explored during the etiology of chronic liver diseases. Steatosis is a common disorder affecting obese patients; moreover, 25% of these patients develop steatohepatitis with an inherent risk for progression to hepatocarcinoma. Increased plasma LPS levels have been detected in the serum of patients with steatohepatitis. We hypothesized that, as a consequence of increased plasma LPS, ER stress could be induced and lead to NLRP3 inflammasome activation and hepatocyte death associated with steatohepatitis progression. In livers from obese mice, administration of LPS or tunicamycin results in IRE1? and PERK activation, leading to the overexpression of CHOP. This, in turn, activates the NLRP3 inflammasome, subsequently initiating hepatocyte pyroptosis (caspase-1, -11, interleukin-1? secretion) and apoptosis (caspase-3, BH3-only proteins). In contrast, the LPS challenge is blocked by the ER stress inhibitor TUDCA, resulting in: CHOP downregulation, reduced caspase-1, caspase-11, caspase-3 activities, lowered interleukin-1? secretion and rescue from cell death. The central role of CHOP in mediating the activation of proinflammatory caspases and cell death was characterized by performing knockdown experiments in primary mouse hepatocytes. Finally, the analysis of human steatohepatitis liver biopsies showed a correlation between the upregulation of inflammasome and ER stress markers, as well as liver injury. We demonstrate here that ER stress leads to hepatic NLRP3 inflammasome pyroptotic death, thus contributing as a novel mechanism of inflammation-mediated liver injury in chronic liver diseases. Inhibition of ER-dependent inflammasome activation and cell death pathways may represent a potential therapeutic approach in chronic liver diseases.
| S-EPMC4650444 | biostudies-literature
Project description:Alterations in the number and protein/gene expression of Hofbauer cells (HBCs) may play a role in microbial-driven/cytokine-mediated placental inflammation, and in subsequent pregnancy complications such as villitis, histologic chorioamnionitis, and the fetal inflammatory response syndrome. Pyroptosis is an inflammatory form of cell death mediated by the inflammasome, a multi-protein complex which drives the processing and secretion of interleukin 1 beta (IL-1β). Pyroptosis can be triggered by bacterial lipopolysaccharide (LPS) and adenosine triphosphate (ATP) in non-placental macrophages through activation of the NLRP3 inflammasome. However, the role of inflammasome activation and pyroptosis in HBC pathophysiology remains unclear. HBCs isolated from human term placentas were treated with or without LPS or ATP, alone or in combination. Treatment of HBCs with both LPS and ATP induced the rapid secretion of high levels of IL-1β and at the same time, cell death associated with nuclear condensation and cellular swelling. HBC treatment with both LPS and ATP induced caspase-1 activation, gasdermin D (GSDMD) cleavage, which mediates pyroptosis, and IL-1β processing. Caspase-1 activation, GSDMD cleavage, IL-1β processing, and IL-1β secretion were all significantly reduced following NLRP3 knockdown; inhibition of caspase-1; and inhibition of P2X7, the receptor that mediates K+ efflux. Together, our data indicate that LPS and ATP treatment stimulated NLRP3 inflammasome activation and pyroptosis in HBCs leading to the rapid release of IL-1β. Since the localization of HBCs confers a unique ability to influence microbial-associated placental and fetal inflammation, these studies suggest a key role for the inflammasome and pyroptosis in mediating HBC driven inflammation.
| S-EPMC7770077 | biostudies-literature
Project description:Inflammasomes are protein complexes assembled upon recognition of infection or cell damage signals, and serve as platforms for clustering and activation of procaspase-1. Oligomerisation of initiating proteins such as AIM2 (absent in melanoma-2) and NLRP3 (NOD-like receptor family, pyrin domain-containing-3) recruits procaspase-1 via the inflammasome adapter molecule ASC (apoptosis-associated speck-like protein containing a CARD). Active caspase-1 is responsible for rapid lytic cell death termed pyroptosis. Here we show that AIM2 and NLRP3 inflammasomes activate caspase-8 and -1, leading to both apoptotic and pyroptotic cell death. The AIM2 inflammasome is activated by cytosolic DNA. The balance between pyroptosis and apoptosis depended upon the amount of DNA, with apoptosis seen at lower transfected DNA concentrations. Pyroptosis had a higher threshold for activation, and dominated at high DNA concentrations because it happens more rapidly. Gene knockdown showed caspase-8 to be the apical caspase in the AIM2- and NLRP3-dependent apoptotic pathways, with little or no requirement for caspase-9. Procaspase-8 localised to ASC inflammasome 'specks' in cells, and bound directly to the pyrin domain of ASC. Thus caspase-8 is an integral part of the inflammasome, and this extends the relevance of the inflammasome to cell types that do not express caspase-1.
| S-EPMC3741496 | biostudies-literature
Project description:INTRODUCTION:There is an increasing prevalence of non-communicable diseases worldwide. Metabolic diseases such as obesity and gestational diabetes mellitus (GDM) increasingly affect women during pregnancy, which can harm pregnancy outcomes and the long-term health and wellbeing of exposed offspring. Both obesity and GDM have been associated with proinflammatory effects within the placenta, the critical organ governing fetal development. METHODS:The purpose of these studies was to model, in vitro, the effects of metabolic stress (high levels of glucose, insulin and saturated lipids) on placental macrophage biology, since these cells are the primary innate immune phagocyte within the placenta with roles in governing maternofetal immune tolerance and antimicrobial host defense. Macrophages were isolated from the villous core of term, human placentae delivered through nonlaboring, elective Cesarean sections and exposed to combinations of elevated glucose (30 mM), insulin (10 nM) and the saturated lipid palmitic acid (palmitate, 0.4 mM). RESULTS:We found that palmitate alone induced the activation of the nucleotide-binding oligomerization domain-like receptor (NLR) Family Pyrin Domain Containing 3 (NLRP3) inflammasome in placental macrophages, which was associated with increased interleukin 1 beta release and an increase in apoptotic cell death. Glucose and insulin neither provoked these effects nor augmented the impact of palmitate itself. DISCUSSION:Our findings confirm an impact of saturated fat on placental macrophage immune activation and could be relevant to the impact of metabolic stress in vivo.
| S-EPMC7034939 | biostudies-literature
Project description:The objective of this study is to examine IL-11-induced mechanisms of inflammatory cell migration to the CNS. We report that IL-11 is produced at highest frequency by myeloid cells among the PBMC cell subsets. Patients with relapsing-remitting multiple sclerosis (RRMS) have an increased frequency of IL-11+ monocytes, IL-11+ and IL-11R+ CD4+ lymphocytes and IL-11R+ neutrophils in comparison to matched healthy controls (HCs). IL-11+ and GM-CSF+ monocytes, CD4+ lymphocytes, and neutrophils accumulate in the cerebrospinal fluid (CSF). The effect of IL-11 in-vitro stimulation, examined using single cell RNA sequencing (scRNAseq), revealed the highest number of differentially expressed genes (DEGs) in classical monocytes, including upregulated NFKB1, NLRP3 and IL1B. All CD4+ cell subsets had increased expression of S100A8/9 alarmin genes involved in NLRP3 inflammasome activation. In IL-11R+-sorted cells from the CSF, classical and intermediate monocytes significantly upregulated the expression of multiple NLRP3 inflammasome-related genes, including complement, IL18, and migratory genes (VEGFA/B) in comparison to blood-derived cells. Therapeutic targeting of this pathway with aIL-11 mAb in mice with RR experimental autoimmune encephalomyelitis (EAE) decreased clinical scores, CNS inflammatory infiltrates and demyelination. aIL-11 mAb treatment decreased the numbers of NFkBp65+, NLRP3+ and IL-1b+ monocytes in the CNS of mice with EAE. The results suggest that IL-11/IL-11R signaling in monocytes represents a therapeutic target in RRMS.
2023-06-21 | GSE233917 | GEO
Project description:BackgroundThrombocytopenia, an early common complication in heatstroke (HS), has been widely considered as a mortality predictor of HS. The mechanism underlying thrombocytopenia in HS remains unknown. It is not known whether NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome is activated in HS platelet, which, in turn, induces platelet activation and thrombocytopenia. This study tried to clarify the activation of the NOD-like receptor signaling pathway under HS conditions and investigate its roles in mediating HS-induced thrombocytopenia.MethodsRat HS models were established in a certain ambient temperature and humidity. Platelets, isolated from blood, were counted and CD62P, an index of platelet activation, was measured by flow cytometry in all rats. The colocalization of NLRP3 inflammasome in platelet was detected by confocal fluorescence microscopy. Mitochondrial-derived reactive oxygen species (ROS) was detected using the molecular probes. Plasma HMGB1 and IL-1β levels were measured by ELISA.ResultsPlatelet activation, showed by upregulated CD62P, and thrombocytopenia were observed in HS rats. HS activated the NLRP3 inflammasome, which was induced by elevated levels of ROS, while the upregulated CD62P and thrombocytopenia triggered by NLRP3 inflammasome were attributed to the high mobility group box protein 1 (HMGB1) inplasma. Moreover, inhibition of the NOD-like receptor signaling pathway in rats with HS suppressed platelet activation and the decline of platelet count. Similar results were obtained when the receptor toll-like receptor 4 (TLR4)/advanced glycation end product (RAGE) was blocked.ConclusionsThe NOD-like receptor signaling pathway induces platelet activation and thrombocytopenia in HS rats. These findings suggested that the NLRP3 inflammasome might be the potential target for HS treatment.
| S-EPMC9357367 | biostudies-literature
Project description:IL-11 induces NLRP3 inflammasome activation
| PRJNA978574 | ENA
Project description:In myeloid cells the inflammasome plays a crucial role in innate immune defenses against pathogen- and danger-associated patterns such as crystalline silica. Respirable mineral particles impinge upon the lung epithelium causing irreversible damage, sustained inflammation and silicosis. In this study we investigated lung epithelial cells as a target for silica-induced inflammasome activation.A human bronchial epithelial cell line (BEAS-2B) and primary normal human bronchial epithelial cells (NHBE) were exposed to toxic but nonlethal doses of crystalline silica over time to perform functional characterization of NLRP3, caspase-1, IL-1?, bFGF and HMGB1. Quantitative RT-PCR, caspase-1 enzyme activity assay, Western blot techniques, cytokine-specific ELISA and fibroblast (MRC-5 cells) proliferation assays were performed.We were able to show transcriptional and translational upregulation of the components of the NLRP3 intracellular platform, as well as activation of caspase-1. NLRP3 activation led to maturation of pro-IL-1? to secreted IL-1?, and a significant increase in the unconventional release of the alarmins bFGF and HMGB1. Moreover, release of bFGF and HMGB1 was shown to be dependent on particle uptake. Small interfering RNA experiments using siNLRP3 revealed the pivotal role of the inflammasome in diminished release of pro-inflammatory cytokines, danger molecules and growth factors, and fibroblast proliferation.Our novel data indicate the presence and functional activation of the NLRP3 inflammasome by crystalline silica in human lung epithelial cells, which prolongs an inflammatory signal and affects fibroblast proliferation, mediating a cadre of lung diseases.
| S-EPMC3607900 | biostudies-other
Project description:Glutamate receptor activation-induced excitotoxicity has been hypothesized to cause retinal ganglion cell (RGC) death in glaucoma and to link mitochondrial dysfunction in both acute and chronic neurodegenerative disorders. However, the relationships among elevated intraocular pressure (IOP), glutamate receptor-mediated excitotoxicity, and mitochondrial dysfunction in glaucoma remains unknown. The goal of this study was to determine whether the N- methyl D-aspartate (NMDA) glutamate receptor antagonist MK801 can block optic atrophy 1 (OPA1) release and subsequent apoptotic cell death, as well as whether acute IOP elevation triggers OPA1 release and alters OPA1 gene and protein expression in the rat retina after ischemia.Sprague Dawley rats received injections of MK801 (10 mg/kg) or vehicle and then transient retinal ischemia was induced by acute IOP elevation. Following subcellular fractionation, changes in cytoplasmic and mitochondrial OPA1 were assessed by western blot analysis. Also, the expression of OPA1 mRNA was measured by Taqman qPCR, the distribution of OPA1 protein was assessed by immunohistochemistry, and apoptotic cell death was assessed by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining.The ~65 and 90 kDa isoforms of OPA1 were increased in the cytosol in the rat retina at 6 h and at 12 h, but only the 90 kDa isoform of OPA1 was decreased at 12 h after ischemia induced by acute IOP elevation. This suggests that ischemic insult induced OPA1 release from the mitochondria in retinas. Pretreatment with MK801 blocked this effect and significantly increased OPA1 immunoreactivity in the inner retinal layers, as well as OPA1 gene expression and total protein expression in retinas at 12 h after ischemia. Further, pretreatment with MK801 prevented apoptotic cell death in retinas at 12 h after ischemia. Following acute IOP elevation, Bcl-2 mRNA expression in retinas was decreased at 3 h and 6 h but increased at 12 h and 24 h. In contrast, Bax mRNA expression in these retinas was increased in the first 12 h and then plateaued. Moreover, pretreatment with MK801 increased Bcl-2 mRNA expression, but did not alter the course of Bax mRNA expression.These results indicate that OPA1 release from mitochondria triggered by acute IOP elevation is inhibited by blockade of glutamate receptor activation. Because this effect was accompanied by increases of Bcl-2 expression, no changes of Bax expression, and blockade of apoptosis, these findings indicate that glutamate receptor activation following acute IOP elevation may lead to a distinct mitochondria-mediated cell death pathway in ischemic retina. These results support further studies to determine whether ischemia-induced OPA1 release may be an important component of the biochemical cascade leading to pressure-related ischemic damage in glaucomatous retina.
| S-EPMC2613079 | biostudies-literature