Green Tea Polyphenol, (-)-Epigallocatechin-3-Gallate, Improves Gut Dysbiosis and Serum Bile Acids Dysregulation in High-Fat Diet-Fed Mice. mouse gut metagenome

Gut microbiota has profound effects on bile acids (BAs) metabolism by promoting deconjugation, dehydrogenation, and dehydroxylation of primary BAs in the distal small intestine and colon. High-fat diet (HFD)-induced dysbiosis of gut microbiota and BAs dysregulation may be involved in the pathology of steatosis in patients with non-alcoholic fatty liver disease (NAFLD). (-)-Epigallocatechin-3-gallate (EGCG), the most abundant polyphenolic catechin in green tea, has been widely investigated on the 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 BAs in HFD-fed mice, and determine the specific bacterial genera to improve the serum BAs dysregulation associated with the anti-hepatic steatosis action by EGCG. After acclimatization, male C57BL/6N mice were divided into three groups and fed with control diet, HFD, or HFD+EGCG at a concentration of 0.32 % for 8 weeks. EGCG significantly inhibited the increases weight, area of fatty lesions, and the triglyceride contents in the liver induced by HFD. Principal coordinate analysis (PCoA) revealed that there were significant differences in microbial structure among groups. At the level of genus, EGCG induced the changes in microbiota composition in HFD-fed mice, showing significantly higher abundance of genera of Adlercreutzia, Akkermansia, Allobaculum, Parabacteroides, and f_Erysipelotrichaceae; g_Clostridium, and significantly lower abundance of genera of Mucispirillum, [Ruminococcus], f_Lachnospiraceae;g_Unclassified, f_Desulfovibrionaceae; g_Unclassified, and Anaerotruncus. EGCG significantly reversed the decreased population of serum primary BAs (cholic acid and beta-muricholic acid) and the increases of secondary BA and taurine-conjugated BAs in HFD-fed mice. Finally, the correlation analysis between BAs profiles and gut microbiota demonstrated the contribution of g_Akkermansia and f_Desulfovibrionaceae; g_Unclassified in the improvement of BAs dysregulation in HFD-fed mice by the treatment with EGCG. In conclusion, the present study suggests that EGCG could improve BA metabolism, especially taurine deconjugation, and suppress fatty liver by improving intestinal environment.