Understanding MAIT cells: pathogenic role in gastritis

Mucosal Associated Innate T (MAIT) cells are innate like T lymphocytes that express a semi-invariant TCR and are restricted by the non-classical MHC class I-related molecule, MR1. These cells are predominantly found at mucosal surfaces and are activated by a novel class of antigens, intermediates of the riboflavin synthesis pathway that are produced by certain class of bacteria and yeasts.

We have examined whether MAIT cells play a role in the pathology of chronic H. pylori infection. We have recently developed highly specific MR1 tetramers that have been used to detect and characterize MAIT cells in mice. Our studies show that MAIT cells play a key role in the regulation of gastric inflammation in H. pylori infection. Using a mouse model that first enriches MAIT cells in the lung, we show repopulation of MAIT cells to other mucosal sites including the stomach. On challenge with H. pylori, these mice develop an accelerated inflammatory response leading to atrophic gastritis. In our model, MAIT cells have a pathogenic rather than protective effect. We are working to understand their role with a view to therapeutic intervention.