HPS Regulates Bile Acid Metabolism In Mice Through FOXA2 To Improve Cholestatic Liver Disease

Hepassocin(HPS)is a growth factor secreted specifically by hepatocytes.The results of previous studies have shown that HPS can promote the proliferation of normal liver cell lines through autocrine action;recombinant HPS protein plays an active role in the repair of acute liver injury.Recent studies have found that the expression of HPS in the liver tissues of nonalcoholic fatty liver disease(NAFLD)mice induced by high-fat diet(HFD)increases;HPS knock out(HPS knock out,HPS-KO)mouse phenotype studies showed that mice were overweight,their plasma lipid distribution and adipose tissue structure were abnormal,suggesting that HPS may play an important role in lipid metabolism.The liver,as the main organ of body material metabolism,regulates the metabolism of cholesterol and triglycerides through the secretion of bile by hepatocytes to play a regulatory role on lipids.As the main organ of the body ’ s material metabolism,liver regulates cholesterol and triglyceride metabolism by secreting bile from hepatocytes to play a regulatory role in lipid metabolism.At present,there are few studies on HPS in bile acid metabolism at home and abroad,and the specific regulatory mechanism is not clear.In our previous study,differential genes in the liver of HPS-KO mice were detected by transcriptome sequencing.Through systematic analysis of the expression profile,it was found that FOXA2,an important transcription factor in the liver,was significantly down-regulated.FOXA2 transcription factor plays an important role in embryonic development and can maintain the normal function of mature hepatocytes in the later stage.At present,FOXA2 has been confirmed to affect lipid metabolism and maintain bile acid homeostasis by directly regulating the expression of genes related to bile acid synthesis and transport.In this study,we first studied the effect of exogenous HPS on FOXA2 expression localization and activity at the in vitro level.By stimulating WRL-68 and hepatic parenchyma cells with different concentrations of HPS,we found that FOXA2 expression was up-regulated at the protein level and transcription level,and the downstream target genes related to bile acid synthesis were also up-regulated.Immunofluorescence showed that HPS and FOXA2 were co-located in the nucleus.The results of high-connotation cell imaging showed that HPS could enhance the activity of hepatic parenchyma cells.In summary,exogenous HPS supplementation promoted the expression and activity of FOXA2.Subsequently,we established a cholestatic liver disease model induced by cholic acid diet(CAD)to study the role of FOXA2 in the CAD model.Our results showed that the serum and liver bile acid levels in CAD model were significantly increased with dyslipidemia,and the protein and transcription levels of FOXA2 in liver tissue were significantly low-regulated.We overexpressed FOXA2 in mouse hepatocytes by tail vein injection of FOXA2 plasmid,and then continued to feed CA diet.Compared with the control group,the serum transaminase was decreased,the inflammatory injury was alleviated,the bile acid and cholesterol levels in liver and serum were decreased,and the lipid accumulation was reduced in the FOXA2 overexpression group,suggesting that FOXA2 supplementation can improve cholestasis liver disease caused by abnormal bile acid metabolism.In order to explore how HPS regulates bile acid metabolism in CAD mice through FOXA2,HPSKO mice were also given CAD intervention.Compared with the wild type mice(WT)group,the bile acid levels in serum and liver of the KO group were significantly increased,indicating that our HPS gene knockout mice also showed significant cholestasis.Liver pathology showed inflammatory cell infiltration,and FOXA2 expression in liver tissue was significantly low-regulated.We speculated that the decrease in FOXA2 expression after HPS knockout might affect the abnormal bile acid metabolism.Subsequently,we found that overexpression of FOXA2 could improve the cholestasis and liver inflammatory injury in HPS-KO mice by backfilling FOXA2.In this study,in vitro and in vivo experiments confirmed that heparin HPS can regulate the expression of FOXA2,and using the CAD model found that HPS may regulate bile acid metabolism through FOXA2,providing new therapeutic targets and strategies for cholestatic liver disease.