Alterations in Bile Acid Metabolism Associated With Inflammatory Bowel Disease

Abstract

Inflammatory bowel disease (IBD) is a chronic relapsing inflammatory disorder closely related to gut dysbiosis, which is associated with alterations in an important bacterial metabolite, bile acids (BAs). Although certain findings pertinent to BA changes in IBD vary among studies owing to the differences in sample type, quantitated BA species, study methodology, and patient characteristics, a specific trend concerning variations of BAs in IBD has been identified. In elaborating on this observation, it was noted that primary BAs and conjugated BAs are augmented in fecal samples but there is a reduction in secondary BAs in fecal samples. It is not entirely clear why patients with IBD manifest these changes and what role these changes play in the onset and development of IBD. Previous studies have shown that IBD-associated BA changes may be caused by alterations in BA absorption, synthesis, and bacterial modification. The complex relationship between bacteria and BAs may provide additional and deeper insight into host-gut microbiota interactions in the pathogenesis of IBD. The characteristic BA changes may generate profound effects in patients with IBD by shaping the gut microbiota community, affecting inflammatory processes, causing BA malabsorption associated with diarrhea, and even leading to intestinal dysplasia and cancer. Thus, therapeutic strategies correcting the alterations in the composition of BAs, including the elimination of excess BAs and the supplementation of deficient BAs, may prove promising in IBD.

hECA: The cell-centric assembly of a cell atlas

“…Their differentiation, activation, and quiescence are regulated by diverse metabolites in the local microenvironment ( Buck et al., 2015 ; Chapman et al., 2020 ; Shyer et al., 2020 ; Yin et al., 2019 ). Recent studies reported that microbial bile acid metabolites promoted the generation of regulatory T cells in the intestine, which is associated with inflammatory bowel disease (IBD) ( Campbell et al., 2020 ; Hang et al., 2019 ; Song et al., 2020 ), suggesting that targeting metabolic pathways of T cell activation and differentiation may improve therapeutic outcomes of patients with IBD ( Li et al., 2021 ). A comprehensive survey of the metabolism of T cells across multiple organs is crucial for better understanding intrinsic responses of T cells to microenvironment changes, but in vivo or in vitro experiments on multiple organs are not easy.…”

hECA: the cell-centric assembly of a cell atlas

“…Their differentiation, activation and quiescence are regulated by the diverse metabolites in different local tissues (Buck et al ., 2015; Chapman et al ., 2020; Shyer et al ., 2020; Yin et al ., 2019). For example, recent studies reported that microbial bile acid metabolites promoted the generation of regulatory T cells in the intestine, which is associated with inflammatory bowel disease (IBD) (Campbell et al ., 2020; Hang et al ., 2019; Song et al ., 2020), suggesting that targeting metabolic pathways of T cell activation and differentiation may improve therapeutic outcomes of IBD patients (Li et al ., 2021). Comprehensive survey of the metabolism of T cells across multiple organs is crucial for better understanding intrinsic responses of T cells to microenvironment changes, but in vivo or in vitro experiments on multiple organs are not easy.…”

Bile Acids: Key Players in Inflammatory Bowel Diseases?

“…Increased primary and conjugated BAs together with decreased secondary BAs in IBD fecal samples appeared to be consistent across the studies [ 10 , 12 , 68 , 69 ]. Despite changes to BAs being observed in other types of samples such as serum, plasma, urine and fasting duodenal bile, a clear trend cannot be identified due to a limited number of studies and their limited consistency [ 70 ].…”