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TRPM2 links oxidative stress to NLRP3 inflammasome activation.

ABSTRACT: Exposure to particulate crystals can induce oxidative stress in phagocytes, which triggers NLRP3 inflammasome-mediated interleukin-1? secretion to initiate undesirable inflammatory responses that are associated with both autoinflammatory and metabolic diseases. Although mitochondrial reactive oxygen species have a central role in NLRP3 inflammasome activation, how reactive oxygen species signal assembly of the NLRP3 inflammasome remains elusive. Here, we identify liposomes as novel activators of the NLRP3 inflammasome and further demonstrate that liposome-induced inflammasome activation also requires mitochondrial reactive oxygen species. Moreover, we find that stimulation with liposomes/crystals induced reactive oxygen species-dependent calcium influx via the TRPM2 channel and that macrophages deficient in TRPM2 display drastically impaired NLRP3 inflammasome activation and interleukin-1? secretion. Consistently, Trpm2(-/-) mice are resistant to crystal-/liposome-induced interleukin-1?-mediated peritonitis in vivo. Together, these results identify TRPM2 as a key factor that links oxidative stress to the NLRP3 inflammasome activation. Therefore, targeting TRPM2 may be effective for the treatment of NLRP3 inflammasome-associated inflammatory disorders.

SUBMITTER: Zhong Z

PROVIDER: S-EPMC3605705 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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TRPM2 links oxidative stress to NLRP3 inflammasome activation.

Zhong Zhenyu Z Zhai Yougang Y Liang Shuang S Mori Yasuo Y Han Renzhi R Sutterwala Fayyaz S FS Qiao Liang L

Nature communications 20130101

Exposure to particulate crystals can induce oxidative stress in phagocytes, which triggers NLRP3 inflammasome-mediated interleukin-1β secretion to initiate undesirable inflammatory responses that are associated with both autoinflammatory and metabolic diseases. Although mitochondrial reactive oxygen species have a central role in NLRP3 inflammasome activation, how reactive oxygen species signal assembly of the NLRP3 inflammasome remains elusive. Here, we identify liposomes as novel activators of ...[more]

PMID: 23511475

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Project description:Poultry meat has a high polyunsaturated fatty acids content, making it vulnerable to oxidative stress. Mitophagy participates in the regulation of oxidative stress and the nucleotide-binding and oligomerization domain (NOD)-like receptor family as well as pyrin domain-containing protein 3 (NLRP3) inflammasome activation. Lactiplantibacillus plantarum P8 (P8) is a probiotic strain with an antioxidant capacity. In the present study, we investigated the effects of P8 on oxidative stress, mitochondrial function, mitophagy, and NLRP3 inflammasome in the breast meat of oxidatively stressed broilers. Four hundred 1-day-old male broilers were assigned to a 2 × 2 factorial design with 2 P8 levels (0 or 1 × 108 cfu/g), either with or without dexamethasone (DEX) injection, for a 21-day experimental period. DEX was injected intraperitoneally once daily from d 16 to 21. The breast meat was collected on d 21. The results showed that P8 supplementation decreased malondialdehyde (MDA) levels, increased superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px), and activated the Keap1-Nrf2 pathway in DEX-injected broilers. Moreover, P8 supplementation downregulated mitochondrial DNA (mtDNA) copy number and increased the expressions of peroxisome proliferator-activated receptor gamma coactivator 1α (PGC-1α), silent information regulator 1 (SIRT1), mitochondrial fusion protein 1 (Mfn1), and optic atrophy protein 1 (OPA1) in DEX-treated broilers. In addition, the decreased mitophagy level in DEX-treated broilers was elevated with P8 supplementation, as reflected by the increased gene expression of autophagy-related gene 5 (ATG5), Bcl-2-interacting protein (Becline-1), Parkin, PTEN-induced kinase 1 (PINK1), light chain 3 II (LC3II)/LC31, and the protein expression of Parkin as well as decreased p62 expression. In addition, P8 supplementation inhibited NLRP3 inflammasome activation by decreasing the transcription of NLRP3, IL-18, cysteinyl aspartate-specific proteinase-1 (Caspase-1), and the expression of NLRP3 and IL-18 in DEX-treated broilers. In conclusion, dietary P8 supplementation alleviates oxidative stress, improves mitophagy, and inhibits NLRP3 inflammasome activation in the breast meat of oxidatively stressed broilers.

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.

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TRPM2 links oxidative stress to NLRP3 inflammasome activation.

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TRPM2 links oxidative stress to NLRP3 inflammasome activation.

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