title: Purinergic receptor X7 is a key modulator of metabolic oxidative stress-mediated autophagy and inflammation in experimental nonalcoholic steatohepatitis.
abstract: Recent studies indicate that metabolic oxidative stress, autophagy, and inflammation are hallmarks of nonalcoholic steatohepatitis (NASH) progression. However, the molecular mechanisms that link these important events in NASH remain unclear. In this study, we investigated the mechanistic role of purinergic receptor X7 (P2X7) in modulating autophagy and resultant inflammation in NASH in response to metabolic oxidative stress. The study uses two rodent models of NASH. In one of them, a CYP2E1 substrate bromodichloromethane is used to induce metabolic oxidative stress and NASH. Methyl choline-deficient diet feeding is used for the other NASH model. CYP2E1 and P2X7 receptor gene-deleted mice are used to establish their roles in regulating metabolic oxidative stress and autophagy. Autophagy gene expression, protein levels, confocal microscopy based-immunolocalization of lysosome-associated membrane protein (LAMP)2A and histopathological analysis were performed. CYP2E1-dependent metabolic oxidative stress induced increases in P2X7 receptor expression and chaperone-mediated autophagy markers LAMP2A and heat shock cognate 70 but caused depletion of light chain 3 isoform B (LC3B) protein levels. P2X7 receptor gene deletion significantly decreased LAMP2A and inflammatory indicators while significantly increasing LC3B protein levels compared with wild-type mice treated with bromodichloromethane. P2X7 receptor-deleted mice were also protected from NASH pathology as evidenced by decreased inflammation and fibrosis. Our studies establish that P2X7 receptor is a key regulator of autophagy induced by metabolic oxidative stress in NASH, thereby modulating hepatic inflammation. Furthermore, our findings presented here form a basis for P2X7 receptor as a potential therapeutic target in the treatment for NASH.
authors.affiliation: Environmental Health and Disease Laboratory, Dept. of Environmental Health Sciences, Univ. of South Carolina, Columbia, SC 29208. schatt@mailbox.sc.edu.
authors.forename: Suvarthi
authors.initials: S
authors.lastname: Das
authors.forename: Ratanesh Kumar
authors.initials: RK
authors.lastname: Seth
authors.forename: Ashutosh
authors.initials: A
authors.lastname: Kumar
authors.forename: Maria B
authors.initials: MB
authors.lastname: Kadiiska
authors.forename: Gregory
authors.initials: G
authors.lastname: Michelotti
authors.forename: Anna Mae
authors.initials: AM
authors.lastname: Diehl
authors.forename: Saurabh
authors.initials: S
authors.lastname: Chatterjee
mesh_terms: D000818:Animals; D001343:Autophagy / Q000502:physiology*; D002273:Carcinogens / Q000494:pharmacology; D002796:Choline Deficiency / Q000378:metabolism; D019392:Cytochrome P-450 CYP2E1 / Q000494:pharmacology; D005234:Fatty Liver / Q000378:metabolism*; D020869:Gene Expression Profiling; D050883:HSC70 Heat-Shock Proteins / Q000378:metabolism; D007249:Inflammation / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D052119:Lysosomal-Associated Membrane Protein 2 / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D023421:Models, Animal; D065626:Non-alcoholic Fatty Liver Disease; D018384:Oxidative Stress / Q000502:physiology*; D011963:Receptors, GABA-A / Q000378:metabolism; D058486:Receptors, Purinergic P2X7 / Q000378:metabolism*; D022882:Trihalomethanes / Q000494:pharmacology
chemical_list: D002273:Carcinogens; D050883:HSC70 Heat-Shock Proteins; D052119:Lysosomal-Associated Membrane Protein 2; C480860:Map1lc3b protein, mouse; D008869:Microtubule-Associated Proteins; D011963:Receptors, GABA-A; D058486:Receptors, Purinergic P2X7; D022882:Trihalomethanes; C025191:bromodichloromethane; D019392:Cytochrome P-450 CYP2E1
keywords: 5,5-dimethyl-1-pyrroline N-oxide-nitrone adducts; CYP2E1; GABA-A receptor-associated protein; cytokines; light chain 3 isoform B; lipid peroxidation; tyrosine nitration