Antarctic krill oil ameliorates liver injury in rats exposed to alcohol by regulating bile acids metabolism and gut microbiota

Bile acids (BAs) metabolism plays an important role in alcohol liver disease through the gut microflora-bile acids-liver axis. Antarctic Krill Oil (AKO) has protective effects on the liver, while whether AKO can protect against liver injury caused by alcohol is unclear. This study investigated the effects of AKO on BAs metabolism and intestinal microbiota in a rat model of alcohol-induced liver disease. Sprague-Dawley rats were randomly divided into five groups: control group, model group, low-dose AKO-treatment group (100 mg/kg/d), high-dose AKO-treatment group (200 mg/kg/d), and AKO control group (200 mg/kg/d). Administration of alcohol (8 to 10 mL/kg/d) for 16 weeks induced liver injury in rats. We found that AKO supplementation significantly protected the liver against alcohol-induced injury, evidenced by allayed hepatic histopathological changes, and inhibited the alcohol-induced elevation of serum biochemical indices. Furthermore, AKO could regulate BAs metabolism by activating the intestinal-hepatic FXR-FGF15-FGFR4 signaling axis with subsequently decreased cholesterol 7α-hydroxylase (CYP7A1) and sterol 12α-hydroxylase (CYP8B1) levels, reduced hepatic BAs production, decreased serum BAs level and increased fecal excretion of BAs. Additionally, 16S rDNA sequencing revealed that the gut microbiome richness and composition were altered in alcohol-treated rats in comparison to the control and AKO-administrated rats. Spearman's correlation analysis showed that differential gut bacterial genera correlated with the levels of BAs profiles in the serum, liver, and feces. These findings suggested that AKO dietary supplementation may protect against alcohol-induced liver injury through modulating BAs metabolism and altering the gut microbiome.