Microbiome and diseases: Inflammatory bowel diseases

Inflammatory bowel diseases, such as Crohn’s disease and ulcerative colitis, are chronically relapsing, immune-mediated disorders of the gastrointestinal tract that have been steadily increasing over the past decades. The hallmark of IBD is an uncontrolled manifestation of intestinal and extraintestinal inflammation within genetically susceptible individuals. Herein, compelling research on host genetics pave the way to a better understanding of disease pathogenesis. Over 200 genetic risk factors have been identified showing a disturbed cross talk of the immune epithelial cell microbiota axis. Additionally, epidemiologic studies pointed toward Western lifestyle and habits as part of central environmental factors contributing to both development and maintenance of intestinal inflammation. In this regard, the gut microbiota progression. The intestinal microbiota was unequivocally shown to be indispensable in orchestrating the development and functionality of the immune system further having a critical impact on both intestinal homeostasis and inflammation in preclinical models. Even though profound changes in the composition of the intestinal microbiota have been frequently observed in human IBD, unraveling cause and consequences of intestinal dysbiosis need further understanding of the interaction between host genetics, microbial ecosystems, and environmental triggers. In this chapter we will discuss different aspects of the etiology of intestinal inflammation and particularly address the role of host-microbe interaction in disease development, progression, and intervention.