Lactobacillus casei YRL577 ameliorates markers of non-alcoholic fatty liver and alters expression of genes within the intestinal bile acid pathway

Non-alcoholic fatty liver disease (NAFLD) has become the main cause of end-stage liver disease. Probiotics have the potential effect of alleviating NAFLD. The aim of this study was to explore functional probiotics and their underlying mechanisms. The bile salt hydrolase (BSH) activity in 34 strains was determined in vitro. Then, C57BL/6 mice were used to explore the effects of probiotics on NAFLD. Body weight and food intake were measured, and serum lipid concentrations, oxidative stress and proinflammatory cytokines levels were determined using commercial kits. The expressions of intestinal bile acid pathway genes were evaluated via real-time PCR. The results showed that Lactobacillus casei YRL577 and L. paracasei X11 had higher BSH activity. L. casei YRL577 significantly reduced liver weight and liver index and could regulate the levels of lipid metabolism, oxidative stress and proinflammatory cytokines as compared with L. paracasei X11. Furthermore, the results indicated that L. casei YRL577 upregulated the mRNA levels of farnesoid X receptor (FXR) and fibroblast growth factor 15 (FGF15), whereas downregulated the mRNA level of apical sodium-dependent bile acid transporter (ASBT). These findings suggested that L. casei YRL577 modified genes in the intestinal bile acid pathway which might contribute to alleviation of NAFLD.