(A) Hepatic NKT cell levels from germ-free mice or matched SPF mice were measured. Data represent mean ± SEM of two pooled experiments. n = 5, P < 0.05, Student’s t-test. (B) cxcl16 mRNA expression in liver tissue from germ-free or SPF mice. Data represent mean ± SEM of two pooled experiments. n = 8 for SPF, 7 for GF. P < 0.05, Student’s t-test. (C) Naive C57BL/6 mice were fed with vancomycin (Vanco), neomycin (Neo) or cefoparazone (Cefo). Hepatic NKT levels were determined. Data represent mean ± SEM of three pooled experiments. n = 18 for H2O, 14 for vancomycin, 14 for neomycin, 10 for cefoperazone. P < 0.05, one-way ANOVA. (D and E) Mice were treated with vancomycin for 1 week and then gavaged with C. scindens or vehicle (cessation). Twenty-four hours after C. scindens gavage, 16S rRNA sequencing analysis of stool samples was performed. The relative abundance of OTUs in the fecal bacterial are shown (D). Time-course study of hepatic NKT levels was performed (E). Data represent mean ± SEM of two pooled experiments. n = 10 for H2O, D0, C. scindens D4, and Cessation D4; 5 for C. scindens D2, Cessation D2, C. scindens D7 and Cessation D7 P < 0.05, two-way ANOVA. (F and G) A20 liver tumors were induced in mice treated with vancomycin or H2O. Mice were colonized with C. scindens or control C. innocuum as illustrated in (F). Cumulative liver tumor counts are shown in (G). Data represent mean ± SEM of two pooled experiments. n = 10 for H2O and Vanco, n = 20 for C. scindens and C. innocuum. P < 0.05, one-way ANOVA. (H) SK-HEP1 cells were treated with different bile acids. CXCL16 mRNA levels were measured by real-time PCR. Data represent mean ± SEM of three pooled experiments. n > 10, P < 0.05, one-way ANOVA. (I) Correlation between primary bile acid CDCA and CXCL16 mRNA expression in nontumor liver tissues from hepatocellular carcinoma or cholangiocarcinoma patients of the TIGER cohort. Pearson correlation coefficient test was performed.