Synergy of Gut Microbiome and Bile Acids in Inducing Cholelithiasis.

Gallstones have remained an expensive and crippling social problem in public health. The pathophysiology of cholelithiasis is not well understood and involves several variables. Even though the risk factors for gallstones and other metabolic syndrome are considered to be similar, there is a long list of risk factors associated with lithogenecity, such as age, parity and obesity. In addition to all this, intricate relationships between the microecology of the gastrointestinal tract and lithogenesis have been highlighted in this context. The gut microbiome and metabolism of bile acids are deeply interwoven. The pathways that regulate the conversion of cholesterol into bile acids in the hepatocytes to promote digestion and to acts as an antimicrobial surfactant in the gastrointestinal tract are well understood. Nevertheless, the gut microecosystem further augments the biotransformation in the enteric region via three mechanisms: dehydroxylation, deconjugation and epimerization. By virtue of these mechanisms, the gut microbiota regulates the bile acid pool by biotransforming primary bile acids into secondary bile acids. The primary bile salt diversifies the gut microbiome and maintains microbial lineage, whereas secondary bile salt perpetuates it. Therefore, it is not wrong to suggest that changes in the microbiome-bile salt equilibrium may contribute to hepatic and gastrointestinal disorders like cholelithiasis, specifically gallbladder stones, choledocholithiasis, and asymptomatic gallstones. Thus, this review serves as a backbone in explaining the entangled connection of bile acid composition-gut microbiome-host’s health. [ABSTRACT FROM AUTHOR]