Fig. 8: Effect of fibrosis-associated bacteria on liver damage induced by an MCD diet.

Mice were acclimated for 1 week on a standard chow diet. Then, they were treated with streptomycin (1 g/L) in drinking water for colonization of four fibrosis-related bacteria. Following 5 weeks, the mice were given daily 200 μL of either bacteria (10⁹ CFU/mouse in PBS) or sham in an MCD diet. a Scheme of the animal experiment. b Effects of the MCD diet and bacteria on serum ALT and AST levels (ALT, ***P = 0.0002 and ***P = 0.0003; AST, ***P = 0.0047 and *P = 0.0281) n = 8 for normal chow, MCD, R. faecis, R. bromii, and M. funifomis group) and n = 13 for V. parvula group. c Representative images of Ruminococcus faecis-treated liver tissues stained with H&E and Sirius red. Scale bar indicates 200 μm. d Comparison of histological NAFLD activity scores calculated on H&E stained liver tissues (***P < 0.0001 and ***P = 0.0006; n = 12 for all groups). e Comparison of collagen proportionate areas measured on Sirius red-stained liver tissues (***P = 0.0002 and ***P = 0.0002; n = 8 for all groups). f Relative fibrogenic mRNA expression of liver harvested from Ruminococcus faecis-treated mice (**P = 0.0016, **P = 0.0016, *P = 0.0293, **P = 0.0047, and *P = 0.0356; n = 5–6 for normal chow and MCD + Ruminococcus faecis, n = 8 for MCD). g Comparison of secondary bile acids levels measured in the cecum of Ruminococcus faecis-treated mice (***P = 0.0003, ***P = 0.0006, and *P = 0.0104; n = 7–8 for normal chow and MCD, n = 8 for MCD + Ruminococcus faecis). The bar graphs indicate the means with SDs. Statistical analysis was performed using a nonparametric Kruskal–Wallis test with Dunn’s multiple comparison test or a two-sided Mann–Whitney test. *P < 0.05, **P < 0.01, ***P < 0.001.