Gasdermin D plays a key role as a pyroptosis executor of non-alcoholic steatohepatitis in humans and mice

Background & Aims: Gasdermin D (GSDMD)-executed programmed necrosis is involved in inflammation and controls interleukin (IL)-1 beta release. However, the role of GSDMD in non-alcoholic steatohepatitis (NASH) remains unclear. We investigated the role of GSDMD in the pathogenesis of steatohepatitis. Methods: Human liver tissues from patients with non-alcoholic fatty liver disease (NAFLD) and control individuals were obtained to evaluate GSDMD expression. Gsdmd knockout (Gsdmd(-/-)) mice, obese db/db mice and their wild-type (WT) littermates were fed with methionine-choline deficient (MCD) or control diet to induce steatohepatitis. The Gsdmd(-/-) and WT mice were also used in a high-fat diet (HFD)-induced NAFLD model. In addition, Alb-Cre mice were administered an adenoassociated virus (AAV) vector that expressed the gasdermin-N domain (AAV9-FLEX-GSDMD-N) and were fed with either MCD or control diet for 10 days. Results: GSDMD and its pyroptosis-inducing fragment GSDMD-N were upregulated in liver tissues of human NAFLD/NASH. Importantly, hepatic GSDMD-N protein levels were significantly higher in human NASH and correlated with the NAFLD activity score and fibrosis. GSDMD-N remained a potential biomarker for the diagnosis of NASH. MCD-fed Gsdmd(-/-) mice exhibit decreased severity of steatosis and inflammation compared with WT littermates. GSDMD was associated with the secretion of pro-inflammatory cytokines (IL-1 beta, TNF-alpha, and MCP-1 [CCL2]) and persistent activation of the NF-kappa B signaling pathway. Gsdmd(-/-) mice showed lower steatosis, mainly because of reduced expression of the lipogenic gene Srebp1c (Srebf1) and upregulated expression of lipolytic genes, including Ppar alpha, Aco [Klk15], Lcad [Acadl], Cyp4a10 and Cyp4a14. Alb-Cre mice administered with AAV9-FLEX-GSDMD-N showed significantly aggravated steatohepatitis when fed with MCD diet. Conclusion: As an executor of pyroptosis, GSDMD plays a key role in the pathogenesis of steatohepatitis, by controlling cytokine secretion, NF-kappa B activation, and lipogenesis. Lay summary: Non-alcoholic fatty liver disease has become one of the most feared chronic liver diseases, because it is the most rapidly growing indication for adult liver transplantation and a major cause of hepatocellular carcinoma. However, the mechanisms involved in the transformation of simple steatosis to steatohepatitis remain unclear. Herein, we show that gasdermin D driven pyroptosis is prominent in patients with non-alcoholic steatohepatitis (NASH), and gasdermin-N domain remains a potential biomarker for the diagnosis of NASH. Gasdermin D plays a key role in the pathogenesis of NASH by regulating lipogenesis, the inflammatory response, and the NF-kappa B signaling pathway, revealing potential treatment targets for NASH in humans. (C) 2017 European Association for the Study of the Liver. Published by Elsevier B.V. All rights reserved.