Systematic Review of Bile Acids Metabolism in Crohn's Disease: Implications for Pathogenesis and Therapeutic...

Crohn's disease (CD) is a chronic inflammatory bowel disorder characterized by transmural inflammation of the gastrointestinal tract. This systematic review aims to unravel the intricate relationship between CD and bile acids (BA), exploring variations and inconsistencies in BA composition related to disease activity, anatomical localization, and surgical history.

Studies reporting BA in CD from PubMed, Scopus, Embase, Cochrane, and WOS have been collected. Data extraction encompassed various study characteristics, population demographics, and BA measurements in serum, intestinal, and fecal compartments. Quality assessment was performed using appropriate tools for different study designs.

Twenty-five studies met the inclusion criteria, comprising 656 patients with CD and 339 healthy controls. Secondary BA-deoxycholic acid and lithocholic acid (LCA)-were consistently reduced in patients with CD, particularly in active disease and following ileal resection. Total serum BA levels showed no significant differences between CD and controls, though conjugated primary BA (cholic acid [CA] and chenodeoxycholic acid [CDCA]) were variably decreased postprandially. Intestinal BA pool size was reduced in ileal and ileocolonic CD, while fecal BA excretion was elevated, especially in patients with ileal resection. Gallbladder bile in CD demonstrated reduced secondary BA fractions and undetectable LCA.

Crohn's disease is associated with significant disturbances in BA metabolism, particularly a reduction in secondary BA and increased fecal excretion, which were mainly due to ileal dysfunction, microbial dysbiosis, and accelerated transit. These alterations may contribute to disease pathogenesis and offer potential as diagnostic biomarkers or therapeutic targets based on BA dynamics.