The Role Of NLRP6 In Alcoholic Hepatitis And Underlying Mechanisms

BackgroundAlcoholic liver disease is a major cause of chronic liver disease.The incidence in China is increasing nowadays.Alcoholic hepatitis is the most severe form of ALD and has high mortality.However,effective treatment for AH is still lacking.Inflammation is considered to be fundamental pathological changes and key components in the pathogenesis of ALD.The NOD-like receptors(NLRs)are a specialized group of intracellular pattern recognition receptors,which participate in inflammatory diseases.This study aims to explore the function and underlying mechanism of NLRP6 in the pathogenesis of alcoholic hepatitis.MethodsThe animal model of alcoholic hepatitis in mice was established according to NIAAA method.RT-q PCR was used to analyze the expression of NLR family members in liver tissues of the ethanol-fed(Et OH-fed)group and pair-fed group.NLRP6 was overexpressed in mice by injecting Recombinant Adeno-Associated Virus into the tail vein.The serum ALT and AST levels were determined by ELISA.Mouse Cytokines and Chemokines RT~2Profiler PCR Array was used to analyze the related cytokines and chemokines involved in the development of alcoholic hepatitis.Lentivirus was used to down-regulate the expression of NLRP6 in mouse macrophage line RAW264 cells and human hepatic stellate cell line LX-2 cells.The changes of NF-κB pathway in mouse liver,RAW264 cells and LX-2 cells was detected by western blot.ResultsAmong the NLR family members,the expression of NLRP6 decreased most significantly in the animal model of AH.Our results demonstrated that overexpression of NLRP6 in vivo obviously alleviated steatosis,inflammation and fibrosis in liver.Meanwhile,the serum ALT and AST levels in mice also decreased.Besides,CCL20 was one of the most significantly up-regulated chemokines in the mouse AH model and CCL20was participated in NLRP6-mediated AH.NLRP6 could inhibit the infiltration of macrophages in liver and secretion of CCL20 from macrophages.Moreover,NLRP6 could also inhibit the activation of NF-κB signaling pathway in vitro and in vivo.Furthermore,the activation,proliferation,and migration of hepatic stellate cells was enhanced after downregulation of NLRP6.ConclusionThe expression of NLRP6 decreased in mice of AH and was inversely correlated with liver inflammation.NLRP6 may play a protective role in the development of AH.NLRP6could inhibit activation of NF-κB signaling pathway in AH.