Green tea polyphenol (epigallocatechin3gallate) improves gut dysbiosis and serum bile acids dysregulation in highfat dietfed mice

Gut microbiota have profound effects on bile acid metabolism by promoting deconjugation, dehydrogenation, and dehydroxylation of primary bile acids in the distal small intestine and colon. Highfat dietinduced dysbiosis of gut microbiota and bile acid dysregula tion may be involved in the pathology of steatosis in patients with nonalcoholic fatty liver disease. Epigallocatechin3gallate (EGCG), the most abundant polyphenolic catechin in green tea, has been widely investigated for its inhibitory or preventive effects against fatty liver. The aim of the present study was to investigate the effects of EGCG on the abundance of gut microbiota and the composition of serum bile acids in highfat dietfed mice and determine the specific bacterial genera that can improve the serum bile acid dysregulation associated with EGCG antihepatic steatosis action. Male C57BL/6N mice were fed with the control diet, highfat diet, or highfat diet + EGCG at a concentration of 0.32% for 8 weeks. EGCG significantly inhibited the increases in weight, the area of fatty lesions, and the triglyceride content in the liver induced by the highfat diet. Principal coordinate analysis revealed significant differences in microbial structure among the groups. At the genus level, EGCG induced changes in the micro biota composition in highfat dietfed mice, showing a significantly higher abundance of Adlercreutzia, Akkermansia, Allobaculum and a significantly lower abundance of Desulfovibrionaceae. EGCG significantly reversed the decreased population of serum primary cholic acid and βmuricholic acid as well as the increased popula tion of taurineconjugated cholic acid, βmuricholic acid and deoxy cholic acid in highfat dietfed mice. Finally, the correlation analysis between bile acid profiles and gut microbiota demonstrated the contribution of Akkermansia and Desulfovibrionaceae in the improvement of bile acid dysregulation in highfat dietfed mice by treatment with EGCG. In conclusion, the present study suggests that EGCG could alter bile acid metabolism, especially taurine deconjugation, and suppress fatty liver disease by improving the intestinal luminal environment.