Vertical sleeve gastrectomy reduces hepatic steatosis while increasing serum bile acids in a weight-loss-independent manner

OBJECTIVE: Our objective was to investigate the role of bile acids in hepatic steatosis reduction after vertical sleeve gastrectomy (VSG). DESIGN AND METHODS: High fat diet (HFD) induced obese C57Bl/6 mice were randomized to: VSG, Sham operation (Sham), Sham operation with pair feeding to VSG (Sham-PF), or non-surgical controls (Naïve). All mice were on HFD until sacrifice. Mice were observed post-surgery and data for body weight, body composition, metabolic parameters, serum bile acid level and composition were collected. Further hepatic gene expression by RNAseq and RT-PCR analysis was assessed. RESULTS: VSG and Sham-PF mice lost equal weight post-surgery while VSG mice had the lowest hepatic triglyceride content at sacrifice. The VSG mice had elevated serum bile acid levels that positively correlated with maximal weight loss. Serum bile composition in the VSG group had increased cholic and tauroursodeoxycholic acid. These bile acid composition changes in VSG mice explained observed downregulation of hepatic lipogenic and bile acid synthetic genes. CONCLUSION: VSG in obese mice results in greater hepatic steatosis reduction than seen with caloric restriction alone. VSG surgery increases serum bile acids that correlate with weight lost post-surgery and changes serum bile composition that could explain suppression of hepatic genes responsible for lipogenesis.