Note: Single-source report; awaiting corroboration.
Scientists at the National Institutes of Health (NIH) and collaborators have identified a key regulatory pathway involved in immune defense against chronic intestinal inflammation linked to inflammatory bowel disease (IBD).
The team studied families with children suffering from severe early-onset IBD and found that these patients share rare, damaging variants in the GPR15 gene. This gene encodes a protein that acts as a homing receptor for a specific group of regulatory immune cells, known as intramucosal GPR15-guided regulatory CD8+ T lymphocytes (CD8+ TIGR cells), directing them into the colon lining.
When harmful mutations disrupt GPR15 function, this homing mechanism fails, resulting in a lack of these protective regulatory cells in the colon. As a result, inflammatory macrophages accumulate, driving severe intestinal inflammation.
This discovery reveals new therapeutic possibilities for IBD, as treatments that restore GPR15 signaling or enhance the migration of these regulatory cells into intestinal tissues could offer more targeted and safer solutions than current broad immune-suppressing therapies.
These findings deepen our understanding of immune regulation in the intestine and the mechanisms behind IBD, including ulcerative colitis and Crohn’s disease—conditions associated with chronic gastrointestinal symptoms and increased colon cancer risk.