Inflammatory bowel disease (IBD) in humans, such as Crohn’s disease and ulcerative colitis, is a complex chronic inflammatory disorder of largely unknown cause in a genetically predisposed host. The incidence of these diseases varies widely between different countries, but overall has increased greatly in recent years, and IBD is now a major public health problem. The gastrointestinal tract of mammals is colonized by a vast range of microorganisms, and this intestinal microbiota is required for intestinal homeostasis and function. Tolerance towards commensal or symbiotic organisms must be maintained to benefit from this colonization. In contrast, colonization with specific pathogenic bacteria can be detrimental to the host, leading to infectious diseases. Thus the host has evolved numerous homeostatic responses towards microbial infections or harmless colonization on the one hand and host defence mechanisms on the other. The multifactorial mechanisms underlying IBD are emphasized by the number of host IBD susceptibility genes that have been identified in recent years. The contributions of the host immune system and the genetic factors that predispose to IBD have been extensively researched and reviewed. This review focuses on the role of bacteria in IBD.
The impact of the microbiota on the pathogenesis of IBD: lessons from mouse infection models. (2010) Nature Reviews Microbiology 8, 564-577 doi:10.1038/nrmicro2403
Inflammatory bowel disease (IBD), including Crohn’s disease and ulcerative colitis, is a major human health problem. The bacteria that live in the gut play an important part in the pathogenesis of IBD. However, owing to the complexity of the gut microbiota, our understanding of the roles of commensal and pathogenic bacteria in establishing a healthy intestinal barrier and in its disruption is evolving only slowly. In recent years, mouse models of intestinal inflammatory disorders based on defined bacterial infections have been used intensively to dissect the roles of individual bacterial species and specific bacterial components in the pathogenesis of IBD. In this Review, we focus on the impact of pathogenic and commensal bacteria on IBD-like pathogenesis in mouse infection models and summarize important recent developments.