Interactions between commensal fungi and the C-type lectin receptor Dectin-1 influence colitis

The intestinal microflora, typically equated with bacteria, influences diseases such as obesity and inflammatory bowel disease (IBD). Here we show that the mammalian gut contains a rich fungal community that interacts with the immune system through the innate immune receptor Dectin-1. Mice lacking Dectin-1 exhibited increased susceptibility t chemically-induced colitis, which was the result of altered responses to indigenous fungi. In humans we identified a polymorphism in the gene for Dectin-1 (CLEC7A) that is strongly linked to a severe form of ulcerative colitis. Together our findings reveal a novel eukaryotic fungal community in the gut (the “mycobiome”) that coexists with bacteria and substantially expands the repertoire of organisms interacting with the intestinal immune system to influence health and disease. Interactions between the commensal microflora and the gut immune system are critical for establishing a balance between immunity and tissue health. Changes in gut bacteria described as “dysbiosis ” have been associated with intestinal inflammation (1-3) and metabolic syndrome (4-6). The vast majority of studies on commensal microbiota hav