The effect of Tauroursodeoxycholic acid (TUDCA) and gut microbiota on murine gallbladder stone formation

Introduction and Objectives: The incidence of gallstone-related disease steadily increased in the last few years. Here, we aimed to investigate the effect of tauroursodeoxycholic acid11 TUDCA: tauroursodeoxycholic acid (TUDCA) on preventing cholesterol gallstones formation in high-fat fed (HFD) mice. Material and Methods: Specific pathogen-free male C57Bl/6 mice were fed a lithogenic diet22 LD: lithogenic diet (LD group) alone or in combination with TUDCA (5 g/kg diet) for 8 weeks. Upon sacrifice, serum, gallbladder, liver and small intestine were collected and the formation of gallstones or crystals in the gallbladder was analyzed. Additionally, the intestinal microbiota, and bile acid composition, serum lipids and hepatic lipids were studied. Results: Cholesterol gallstones with cholesterol crystals formed in mice of the LD-fed group (15/15, 100%). However, only cholesterol crystals were found in three mice without the presence of any gallstone in the TUDCA-treated group. Both serum and hepatic total cholesterol levels in the TUDCA group were significantly decreased compared with the LD group. Concomitantly, mRNA expression of Abcg5 and Abcg8 was significantly lower in the liver of the TUDCA group whilst mRNA transcripts for Abcb11, Acat2, and Cyp27 were significantly increased compared with the LD group. Additionally, the gallbladder cholesterol saturation index (1.06 ± 0.15) in the TUDCA group was significantly decreased compared with the LD group. Interestingly, the ratio of Firmicutes/Bacteroides in the TUDCA group was increased 3x fold. Conclusions: TUDCA can inhibit the absorption and synthesis of lipids in the small intestine by improving the intestinal microbiota in HFD-fed mice, thus reducing gallstone formation