Fast Facts: The Gut Microbiome by Fergus Shanahan

Author:Fergus Shanahan
Format: epub

Figure 7.1 Gut microbiota identified to be increased or decreased in abundance in most, but not all, studies of patients with active inflammatory bowel disease. Collectively, these microbial disturbances are associated with a shift toward a pro-inflammatory response and alterations in bile acid metabolism, tryptophan metabolism and SCFA production. AHR, aryl hydrocarbon receptor; SCFA, short-chain fatty acid.

Discussions of the microbiota in IBD are usually cast as an imbalance with loss of protective commensals and expansion of pathobionts including a secondary expansion of Proteobacteria due to changes in oxygen tension in the inflamed bowel (Figure 7.1). The microbial imbalance is usually linked with a corresponding imbalance in anti-inflammatory and pro-inflammatory microbial metabolites. This binary language and logic may be simplistic and does not take into account interactions among microbes. Moreover, cross-sectional studies in humans with Crohn’s and ulcerative colitis show that microbial disturbances are strongly associated with active inflammation and are less evident in areas of the bowel that are non-inflamed.⁷ In addition, longitudinal studies of the same patients in relapse and remission are consistent with many of the microbial abnormalities being secondary to the inflammatory state.⁸ However, there is evidence for different microbes contributing to different phases or complications particularly in advanced Crohn’s disease⁹–¹⁴ (Table 7.1). In addition, prospective study of first-degree relatives of patients with Crohn’s disease has found a preclinical gut microbiome signature associated with future development of Crohn’s disease

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.