The multifaceted role of the inflammasome in inflammatory bowel diseases.

Inflammasomes are intracellular multiprotein complexes that coordinate the maturation of interleukin (IL)-1 beta and IL-18 in response to pathogens and metabolic danger. Both cytokines have been linked to intestinal inflammation. However, recently evolving concepts ascribe a major role to the inflammasome in maintaining intestinal homeostasis. This review recapitulates its position in the development of inflammatory bowel disease, thereby outlining a model in which hypo- as well as hyperfunctionality can lead to an imbalance of the system, depending on the specific cell population affected. In the epithelium, the inflammasome is essential for regulation of permeability and epithelial regeneration through sensing of commensal microbes, while excessive inflammasome activation within the lamina propria contributes to severe intestinal inflammation.