Vitamin A plays protective role in inflammatory bowel disease
7 June 2013
Scientists at Trinity College Dublin have discovered that Vitamin A can reduce the damaging immune responses that lead to inflammatory bowel disease.
A research team at the School of Biochemistry and Immunology in the Trinity Biomedical Sciences Institute showed that giving mice retinoic acid, a dietary metabolite of Vitamin A, can protect them against intestinal inflammation.
Intestinal inflammation is caused by immune cells in the gut that release inflammatory cytokines, such as IL-17 in response to intestinal bacteria. Other anti-inflammatory cytokines, such IL-22 have the opposite effect of suppressing inflammation and inducing tissue repair.
The research showed that retinoic acid turns on IL-22, and inhibits IL-17 from two immune cells types found in the intestine, called γδ T cells and innate lymphoid cells (ILCs). The net effect of this intervention is to reduce the damaging effect of the gut bacteria and to promote recovery of the damaged tissue in the intestine.
The research has been published in the The Journal of Experimental Medicine .
Inflammatory bowel diseases (IBD) include Crohn’s disease and ulcerative colitis and affect over 2 million people in Europe and more than 15,000 in Ireland. The diseases are characterised by inflammation and damage to the intestine caused by a combination of genetic and environmental factors. The damaging inflammation is mediated by immune cells that infiltrate the gut tissue and are activated locally by bacteria normally resident in our gastrointestinal tracts. In certain individuals genetic or environmental influences can upset the normal immune system balance leading to excessive inflammation and diseases, like IBD.
Team leader Professor Mills said: “Our finding provide valuable new information on the ‘ying and yang’ of the immune system and how its dysregulation can lead to inflammatory diseases, such as ulcerative colitis and Crohn’s disease. On a practical level it has confirmed the importance of Vitamin A-rich green and root vegetables in our diet, and how Vitamin A helps to promote a healthier gut by stimulating the production of protective molecules in a hostile gut environment.”
1. Mielke LA, et al. Retinoic acid expression associates with enhanced IL-22 production by γδ T cells and innate lymphoid cells and attenuation of intestinal inflammation. Brief Definitive Report. The Journal of Experimental Medicine. http://jem.rupress.org/content/early/2013/05/14/jem.20121588?papetoc
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