Dataset Information

Ezetimibe ameliorates steatohepatitis via AMP activated protein kinase-TFEB-mediated activation of autophagy and NLRP3 inflammasome inhibition.

ABSTRACT: Impairment in macroautophagy/autophagy flux and inflammasome activation are common characteristics of nonalcoholic steatohepatitis (NASH). Considering the lack of approved agents for treating NASH, drugs that can enhance autophagy and modulate inflammasome pathways may be beneficial. Here, we investigated the novel mechanism of ezetimibe, a widely prescribed drug for hypercholesterolemia, as a therapeutic option for ameliorating NASH. Human liver samples with steatosis and NASH were analyzed. For in vitro studies of autophagy and inflammasomes, primary mouse hepatocytes, human hepatoma cells, mouse embryonic fibroblasts with Ampk or Tsc2 knockout, and human or primary mouse macrophages were treated with ezetimibe and palmitate. Steatohepatitis and fibrosis were induced by feeding Atg7 wild-type, haploinsufficient, and knockout mice a methionine- and choline-deficient diet with ezetimibe (10 mg/kg) for 4 wk. Human livers with steatosis or NASH presented impaired autophagy with decreased nuclear TFEB and increased SQSTM1, MAP1LC3-II, and NLRP3 expression. Ezetimibe increased autophagy flux and concomitantly ameliorated lipid accumulation and apoptosis in palmitate-exposed hepatocytes. Ezetimibe induced AMPK phosphorylation and subsequent TFEB nuclear translocation, related to MAPK/ERK. In macrophages, ezetimibe blocked the NLRP3 inflammasome-IL1B pathway in an autophagy-dependent manner and modulated hepatocyte-macrophage interaction via extracellular vesicles. Ezetimibe attenuated lipid accumulation, inflammation, and fibrosis in liver-specific Atg7 wild-type and haploinsufficient mice, but not in knockout mice. Ezetimibe ameliorates steatohepatitis by autophagy induction through AMPK activation and TFEB nuclear translocation, related to an independent MTOR ameliorative effect and the MAPK/ERK pathway. Ezetimibe dampens NLRP3 inflammasome activation in macrophages by modulating autophagy and a hepatocyte-driven exosome pathway.

SUBMITTER: Kim SH

PROVIDER: S-EPMC5640190 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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Ezetimibe ameliorates steatohepatitis via AMP activated protein kinase-TFEB-mediated activation of autophagy and NLRP3 inflammasome inhibition.

Kim Soo Hyun SH Kim Gyuri G Han Dai Hoon DH Lee Milim M Kim Irene I Kim Bohkyung B Kim Kook Hwan KH Song Young-Mi YM Yoo Jeong Eun JE Wang Hye Jin HJ Bae Soo Han SH Lee Yong-Ho YH Lee Byung-Wan BW Kang Eun Seok ES Cha Bong-Soo BS Lee Myung-Shik MS

Autophagy 20170921 10

Impairment in macroautophagy/autophagy flux and inflammasome activation are common characteristics of nonalcoholic steatohepatitis (NASH). Considering the lack of approved agents for treating NASH, drugs that can enhance autophagy and modulate inflammasome pathways may be beneficial. Here, we investigated the novel mechanism of ezetimibe, a widely prescribed drug for hypercholesterolemia, as a therapeutic option for ameliorating NASH. Human liver samples with steatosis and NASH were analyzed. Fo ...[more]

PMID: 28933629

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Project description:Background and purposeIL-1β produced by macrophages via the NOD-, LRR- and pyrin domain-containing 3 (NLRP3) inflammasome, mediates the inflammatory crosstalk between macrophages and adipocytes. In our previous study, (16S,20S,24R)-12β-acetoxy-16,23-epoxy-24,25-dihydroxy-3β-(β-D-xylopyranosyloxy)-9,19-cyclolanost-22(23)-ene (AEDC), a cycloartane triterpenoid isolated from Actaea vaginata (Ranunculaceae), was found to possess anti-inflammatory effect on LPS-treated RAW264.7 macrophages. This study was designed to investigate whether AEDC modulates macrophage-adipocyte crosstalk to alleviate adipose tissue inflammation.Experimental approachThe anti-inflammatory effect of AEDC was evaluated on LPS plus ATP-induced THP-1 macrophages and C57BL/6J mice. The expression of autophagy-related and NLRP3 inflammasome complex proteins was analysed by western blots, immunofluorescence staining and co-immunoprecipitation. The pro-inflammatory cytokines levels were determined by ELISA kits. The adipose tissue inflammation was evaluated by histological analysis and immunohistochemical staining.Key resultsAEDC (5 and 10 μM) activated autophagy, which in turn suppressed the NLRP3 inflammasome activation and IL-1β secretion in THP-1 macrophages. AEDC increased the expression of SIRT3 deacetylase and enhanced its deacetylating activity to reverse mitochondrial dysfunction and activate AMP-activated protein kinase, which together induced autophagy. Moreover, AEDC (10 μM) attenuated macrophage conditioned medium-induced inflammatory responses in adipocytes and blocked THP-1 macrophages migration towards 3T3-L1 adipocytes. In inflammation mice, AEDC (5 and 20 mg·kg-1 ) treatment reduced the levels of pro-inflammatory cytokines in serum and epididymal adipose tissue and reduced macrophage infiltration to alleviate adipose tissue inflammation.Conclusion and implicationsAEDC attenuated the inflammatory crosstalk between macrophages and adipocytes through SIRT3-autophagy-mediated NLRP3 inflammasome inhibition, which might used for the treatment of adipose tissue inflammation-related metabolic disorders.

Project description:Background and purposeRegulating P2X7 receptor-mediated activation of NLRP3 inflammasomes could be a therapeutic strategy to treat alcoholic hepatosteatosis. We investigated whether this process was modulated by gentiopicroside, the main active secoiridoid glycoside from Gentiana manshurica Kitagawa.Experimental approachIn vivo models of acute and chronic alcoholic hepatosteatosis were established by intragastrically administered ethanol or using chronic plus binge ethanol feeding of Lieber-DeCarli liquid diet to male C57BL/6 mice. In vitro, HepG2 cells were treated with ethanol. RAW 264.7 macrophages and murine bone marrow-derived macrophages (BMDMs) were stimulated with LPS and ATP.Key resultsIn both the acute and chronic alcohol-induced mouse hepatosteatosis models, gentiopicroside decreased serum aminotransferases and triglyceride accumulation. Up-regulated SREBP1, down-regulated PPARα and phosphorylated acetyl-CoA carboxylase caused by acute and chronic alcohol feeding were modulated by gentiopicroside, through the elevation of LKB1 and AMPK. Suppression of P2X7 receptor-NLRP3 activation by gentiopicroside inhibited IL-1β production. In ethanol-exposed HepG2 cells, gentiopicroside reduced lipogenesis and promoted lipid oxidation via activation of P2X7 receptor-NLRP3 inflammasomes. Genetic or pharmacological blockade of P2X7 receptors enhanced AMPK activity and reduced SREBP1 expression in ethanol-treated HepG2 cells. Gentiopicroside down-regulated P2X7 receptor-mediated inflammatory responses in LPS/ATP-stimulated RAW 264.7 macrophages and BMDMs. IL-1β from macrophages accelerated lipid accumulation in hepatocytes. Depleting macrophages by clodronate liposomes ameliorated alcoholic hepatosteatosis, and it was further alleviated by gentiopicroside.Conclusions and implicationsActivation of LKB1/AMPK signalling by gentiopicroside was mediated by the P2X7 receptor-NLRP3 inflammasome, suggesting the therapeutic value of blocking P2X7 receptors in the treatment of alcoholic hepatosteatosis.

Dataset Information

Ezetimibe ameliorates steatohepatitis via AMP activated protein kinase-TFEB-mediated activation of autophagy and NLRP3 inflammasome inhibition.

Publications

Ezetimibe ameliorates steatohepatitis via AMP activated protein kinase-TFEB-mediated activation of autophagy and NLRP3 inflammasome inhibition.

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