New insights into Th9 cells in inflammatory bowel diseases.

The involvement of T helper cells in the pathogenesis of inflammatory bowel diseases (IBD), including Crohn's disease and ulcerative colitis, has been a subject of considerable research interest. The clinical picture of IBD is characterised by chronic intestinal inflammatory processes that may lead to complications such as stenoses, abscesses, fistulas and colorectal cancer. Recent findings have indicated that T helper 9 (Th9) cells, which secrete the cytokine IL-9, play a role in the pathogenesis of IBD. These cells have been observed to damage the intestinal epithelium by IL-9 production and to amplify the mucosal inflammatory immune response by activating other immune cells. Studies utilising murine models of chronic intestinal inflammation have demonstrated that targeting IL-9 or Th9 cells can alleviate inflammatory responses. In consideration of these findings, it will be of interest to delve into the potential of neutralizing IL-9 function as a therapeutic intervention for patients suffering from IBD.