Correlation between cholecystectomy and development of nonalcoholic liver disease in the mouse model

Abstract

Background: Several clinical studies have suggested a strong correlation between cholecystectomy and the incidence of non-alcoholic fatty liver disease (NAFLD) although the exact correlation and causal relationship are unclear. This study aimed to investigate whether cholecystectomy increases the incidence of NAFLD or aggravates pre-existing NAFLD. Methods: Standard diet-fed and high-fat (HF) diet-fed mice were subjected to sham operation and cholecystectomy. In study 1, 20 standard diet-fed C57BL/6N mice were sacrificed at months 1, 2, and 4 post-surgery. Meanwhile, in study 2, 25 HF diet-induced NAFLD C57BL/6N mice were biopsied at months 2 and 3 post-surgery and sacrificed at month 6 post-surgery. The hepatic fatty acid and bile acid metabolic pathways and the hepatic bile composition were evaluated. Results: The bodyweight and biochemical parameters (hepatic enzyme, triglyceride, and cholesterol levels) were not significantly different between the standard diet-fed sham and cholecystectomy groups. The NAFLD activity score and the levels of hepatocyte apoptosis markers ( Krt18 expression and DNA fragmentation) and de novo lipid synthesis genes were not significantly different between the standard dietfed sham and cholecystectomy groups. Cholecystectomy did not exacerbate hepatic steatosis, inflammation, and ballooning in the HF diet-fed mice. Hepatic bile acid composition was not markedly different in the sham and cholecystectomy groups fed on standard or HF diet. Cholecystectomy significantly downregulated Cyp7a1 and Cyp27a1 mRNA levels at months 1 and 4 post-surgery but did not affect the degree of steatosis and triglyceride levels. Analysis of bile acid metabolism revealed that taurine-conjugated bile acids were significantly downregulated in the standard diet-fed and high- fat diet-fed mice, but the histological and biochemical parameters were not markedly different. Conclusions: Cholecystectomy did not increase the incidence of NAFLD in standard diet- fed mice. Additionally, NAFLD incidence was not significantly different between the HF diet-fed sham and cholecystectomy groups. Furthermore, the histological parameters were not markedly different between the sham and cholecystectomy groups fed on standard or HF diet. These findings suggest that cholecystectomy does not induce NAFLD.