Immune and nonimmune components orchestrate the pathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) pathogenesis is driven by the interactions between the innate and the adaptive immune system. Both systems are actually expressed not only by immune cells, but also by essentially all types of nonimmune cells. Nonimmune cells have classically been considered as simple targets of the aberrant inflammatory process occurring in IBD. However, the discovery that many of the functions traditionally attributed to immune cells are also performed by nonimmune cells has caused a shift to a multidirectional hypothesis in which nonimmune cells and even acellular elements are considered active players of IBD pathogenesis. The aim of this review is to summarize the current role played by each cell type in IBD pathogenesis.