Mucosal immune responses to fungi and the implications for inflammatory bowel disease.

PURPOSE OF REVIEW: The intestinal microbiota plays a central role in inflammatory diseases of the gut. Although most investigations regarding how the mucosal immune system interacts with the microbiota have focused on bacteria, recent studies are elucidating the additional role of commensal fungi in health and disease in the gut.

RECENT FINDINGS: New technical approaches are defining the makeup of the fungal communities in the intestines of humans and mice. The reported composition of these communities is influenced by the approaches used to define the fungi. Changes in the intestinal mycobiota are associated with gut inflammation in patients with inflammatory bowel disease and in mouse models of colitis. Recent studies are beginning to elucidate the mechanisms by which the mucosal immune system interacts with and is influenced by intestinal fungi.

SUMMARY: Studies clearly demonstrate the presence of intestinal fungi and document the ability of the mucosal immune system to recognize and respond to fungi. Future studies will further investigate whether intestinal fungi directly influence intestinal disease and what cellular, molecular, and genetic mechanisms contribute.