Bile acid-induced IRF3 phosphorylation mediates cell death, inflammatory responses and fibrosis in cholestasis-induced liver and kidney injury via regulation of ZBP1

Abstract

Cell death and inflammation play critical roles in chronic tissue damage caused by cholestatic liver injury leading to fibrosis and cirrhosis. Liver cirrhosis is often associated with kidney damage that is a severe complication with poor prognosis. Interferon regulatory factor 3 (IRF3) is known to regulate apoptosis and inflammation, but its role in cholestasis remains obscure. In this study, we discovered increased IRF3 phosphorylation (p-IRF3) in the liver of patients with primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC). In the bile duct ligation (BDL) model of obstructive cholestasis in mice, we found that tissue damage was associated with increased p-IRF3 expression in the liver and kidney. IRF3 knockout (Irf3 -/- ) mice showed significantly attenuated liver and kidney damage and fibrosis compared to WT mice after BDL. Cell death pathways, including apoptosis, necroptosis and pyroptosis, inflammasome activation and inflammatory responses were significantly attenuated in Irf3 -/- mice. Mechanistically, we show that bile acids induced IRF3 phosphorylation in vitro in hepatocytes. In vivo, activated IRF3 positively correlated with increased expression of its target gene, Z-DNA Binding Protein 1 (ZBP1), in the liver and kidney. Importantly, we also found increased ZBP1 in the liver of patients with PBC and PSC. We discovered that ZBP1 interacted with RIP1, RIP3 and NLRP3, thereby revealing its potential role in regulation of cell death and inflammation pathways. In conclusion, our data indicate that bile acid-induced IRF3 phosphorylation and the IRF3-ZBP1 axis play a central role in the pathogenesis of cholestatic liver and kidney injury.