Disturbances of the Gut Microbiota and Microbiota-Derived Metabolites in Inflammatory Bowel Disease

Abstract

Inflammatory bowel disease (IBD), comprising Crohn’s disease (CD) and ulcerative colitis (UC), is characterized as a chronic and recurrent inflammatory disease whose pathogenesis is still elusive. The gut microbiota exerts important and diverse effects on host physiology through maintaining immune balance and generating health-benefiting metabolites. Many studies have demonstrated that IBD is associated with disturbances in the composition and function of the gut microbiota. Both the abundance and diversity of gut microbiota are dramatically decreased in IBD patients. Furthermore, some particular classes of microbiota-derived metabolites, principally short-chain fatty acids, tryptophan, and its metabolites, and bile acids have also been implicated in the pathogenesis of IBD. In this review, we aim to define the disturbance of gut microbiota and the key classes of microbiota-derived metabolites in IBD pathogenesis. In addition, we also focus on scientific evidence on probiotics, not only on the molecular mechanisms underlying the beneficial effects of probiotics on IBD but also the challenges it faces in safe and appropriate application.

Advancements in hydrogel-based drug delivery systems for the treatment of inflammatory bowel disease: a review

“…However, in IBD, this delicate balance between the host and microbiota is disrupted, leading to ecological dysregulation, which manifests itself in altered composition, diversity, and function of the gut flora. 40 It is typically characterized by reduced microbial diversity and overgrowth of potentially harmful bacteria, especially a rapid reduction of Firmicutes and Bacteroidetes, which include short-chain fatty acid (SCFA) producers with anti-inflammatory effects. 41,42 In addition, beneficial bacteria, such as Clostridium pallidum and Bifidobacterium bifidum, known to have anti-inflammatory properties, were also reduced.…”

Inflammatory Bowel Diseases and Gut Microbiota

“…SCFAs contribute to biological homeostasis by being used as an energy source for colonic epithelial cells and fatty acid synthesis in peripheral tissues [ 81 ]. SCFAs play an important role in host metabolic regulation and may contribute to improving the amelioration of immune disorders such as IBD [ 82 ]. SCFAs were decreased in the feces of patients with IBD compared with that of healthy subjects, which might be attributed to dietary differences [ 83 ].…”

Urolithin A Alleviates Colitis in Mice by Improving Gut Microbiota Dysbiosis, Modulating Microbial Tryptophan Metabolism, and Triggering AhR Activation

“…On the one hand, pro-inflammatory cytokines could activate MAPK signaling pathways and regulated several downstream transcription factors involved in IBD, and on the other hand, the activation of MAPK increased the production and secretion of pro-inflammatory cytokines, such as interleukin (IL)-1β and tumor necrosis factor (TNF)-α . In addition, the gut microbiota is also widely believed to play a critical role in triggering IBD development . The fact that completely different profiles and abundances of gut microbiota metabolites were detected in serum, urine, and feces between germ-free and conventionally colonized mice indicated the importance of microbial metabolites in host biology .…”

“…6 In addition, the gut microbiota is also widely believed to play a critical role in triggering IBD development. 7 The fact that completely different profiles and abundances of gut microbiota metabolites were detected in serum, urine, and feces between germ-free and conventionally colonized mice indicated the importance of microbial metabolites in host biology. 8 Microbiota-derived metabolites, such as short-chain fatty acids (SCFAs), mediumchain fatty acids(MCFAs), 9 and bile acids (BAs), 10 were reported to protect host immunity, balance energy metabolism, and impair the mucosal barrier.…”