Comprehensive Prescription of Herbs (CPH) Improves Bile Lithogenicity via Regulation of ABCB4, PPAR-α, and LXR Expression: A Pilot Study

Abstract

Background: Comprehensive prescription of herbs (CPH) has been utilized for the clinical treatment of gallstone disease (GSD) in China. Our study attempted to observe how lipid-related genes interacted with other candidate gallstone genes after prolonged intake of a lithogenic diet (LD) and to assess the molecular mechanism through which CPH exerted biological effects on lipid-related genes in a mouse model of cholelithiasis. Methods: Gallstones were induced in susceptible C57BL/6J mice fed an LD. The mice were randomly assigned to five groups: (A) 0 weeks plus LD (0+LD), (B) 4+LD, (C) 8+LD, (D) LD+normal saline (NS), and (E) LD+CPH. Equal amounts of CPH or NS were administered by gavage with LD for 8 weeks consecutively. A qualitative analysis of gallstones, gallstone incidence, and the microstructure of liver tissue was performed. Bile lipids and the cholesterol saturation index (CSI) were measured. The expression of lipid-related genes was analyzed by real-time polymerase chain reaction (RT-PCR). Results: The gallstone incidence in the 8+LD and LD+NS groups was 100%. No gallstones, floccules, or crystals were evident in the 0+LD group. The gallstone rates in the 4+LD and LD+CPH groups were 50% and 40%, respectively, and the rates of floccules and crystals were 10% and 10%, respectively. The levels of bile total cholesterol (TC), phospholipids (PL), and total bile acid (TBA), as well as the CSI, in the 4+LD and 8+LD groups were significantly higher than those in the 0+LD group, whereas TBA tended to decrease in the 8+LD group. CPH decreased the levels of TC, PL, and CSI and increased TBA. RT-PCR demonstrated that the expression of adenosine triphosphate-binding cassette subfamily G members 5 and 8 (ABCG5, ABCG8), peroxisome proliferator activated receptor alpha (PPAR-α), liver X receptor (LXR), and adenosine triphosphate-binding cassette subfamily B member 4 (ABCB4) was significantly upregulated and that the expression of sterol regulatory element-binding protein 2 (SREBP2), cholesterol 7-α hydroxylase (CYP7A1), and oxysterol 7-α hydroxylase (CYP7B1) was notably suppressed between 0 and 8 weeks of LD administration. CPH treatment may relieve gallstone formation through the downregulation of ABCB4, PPAR-α, and LXR transcription. Conclusions: Abnormal expression of relevant lipid-related genes and dysfunction of lipid metabolism contributes to gallstone formation. CPH may exert cholagogic function and dissolve gallstones via the normalization of lipid compositions, the reversal of tissue lesions, and the reduction in ABCB4, PPAR-α, and LXR expression.