inflammatory bowel disease is the generic term for a range of “autoinflammatory” diseases including Crohn's disease and ulcerative colitis.
pathogenesis
mechanisms are not well understood as yet
Hepworth et al 1) propose the following mechanism:
a subset of innate lymphoid cells called ILC3 cells which normally reside in the lamina propria of the bowel and in mesenteric lymph nodes, selectively kill CD4 T cell lymphocytes that are capable of responding to bacterial antigen originating from the gut.
normally these ILC3 cells prevent the immune system from mounting an inflammatory response to these non-pathogenic bacteria gut flora in a similar way as thymic medullary epithelial cells or dendritic cells of the thymus kill off specific CD4 T cells to reduce the risk of auto-immune diseases
biopsies of children with Crohn's disease reveal a deficiency in the expression of ILC3-instrinsic MHC class II suggesting this could be a key component of the pathogenesis