Objective:Primary biliary cholangitis(PBC)is a chronic progressive cholestatic liver disease.In recent years,researchers have found that cysteine-rich angiogenic inducer 61(Cyr61,also known as CCN1)has a potential role in reducing portal inflammation in patients with PBC.This study aimed to explore the relationship between Cyr61 and PBC to provide new ideas and an experimental basis for the clinical treatment of PBC.Methods:After induction of the overexpression of Cyr61 in a mouse model of PBC using recombinant adenovirus,hematoxylin and eosin staining and pathological scores were used to indicate intrahepatic inflammation and bile duct damage.Real-time PCR was used to detect changes in inflammation-related cytokines in the liver.To further study the mechanism,we assessed whether Cyr61 protects bile duct epithelial cells from cytotoxic effects.Results:Serum and hepatic Cyr61 levels were increased in the murine model of PBC.Overexpression of Cyr61 alleviated hepatic inflammation and bile duct injury in vivo.Cyr61 inhibited the cytotoxic effects of CD8+T cells by acting on biliary epithelial cells(BECs)in vitro.Conclusion:Our results provide novel insight into the pathogenesis of PBC and suggest that Cyr61 plays a dominant role in the cytotoxic effects on BECs in PBC.Consequently,therapeutic strategies targeting Cyr61 could be a potent therapy for PBC.