inflammatory bowel disease (IBD)

introduction

inflammatory bowel disease is the generic term for a range of “autoinflammatory” diseases including Crohn's disease and ulcerative colitis.

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

corticosteroids
sulphasalazine (salazopyrine)
TNF antagonists
monoclonal antibodies to integrin:
- iv vedolizumab every 8wks (introduced in Australia in 2015)

¹⁾

NEJM 373;24 Dec 10 2015 and Science 2015; 348:1031-5;