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 but 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 has 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 the digestion and to acts as an antimicrobial surfactant in the gastrointestinal tract is well understood. Nevertheless, the gut microecosystem further augments the biotransformation in the enteric region via three mechanisms: dehydroxylation, deconjugation and epimerization. By the 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 gut microbiome and maintains microbial lineage, whereas secondary bile salt perpetuate it.Therefore, it is not wrong to suggest that changes in the microbiome-bile salt equilibrium may contribute to the hepatic and gastrointestinal disorders like cholelithiasis, specifically gallbladder stones, choledocholithiasis, and asymptomatic gallstones.Thus, this review serve as a backbone in explaining the entangled connection of bile acid composition-gut microbiome-host’s health.