The microbiome has received considerable attention lately, with most of that attention focused on the bacterial population, but a study published yesterday in the journal Science, seems to indicate that the gut’s fungal community may play a large role in intestinal health as well. According to the study from Weill Cornell Medical scientists, immune cells that process food and bacterial antigens in the intestine also control the gut population of fungi. Defects in these immune cells may lead to some cases of Crohn’s disease and other forms of inflammatory bowel disease (IBD).
Advances in instrumentation have led to the recent recognition of the large population of fungal cells in the gut, called the mycobiome, but the gut’s mechanism for controlling these cells remained unclear.
To identify the type of immune cells that control gut fungi, the researchers chemically induced colitis in mice and added fungus to see if that fungus would overgrow. Mice lacking a type of phagocyte called CX3CR1+ phagocytes were observed to be far more susceptible to the fungus. Antifungal treatment reversed signs of the disease.
A study of more than 500 Crohn’s disease patients revealed that those who carry a homozygous mutation in the CX3CR1 gene have reduced antifungal response.
The findings could help in building better treatment plans for those with the CX3CR1 gene variant. These patients may have previously been misdiagnosed as they don’t generate an antifungal antibody called ASCA, commonly used as a diagnostic marker for several diseases including Crohn’s.
Image: This is opportunistic fungus called candida albicans (red) engulfed by CX3CR1+ phagocytes (green) in the gut villi (blue). Image courtesy of Dr. Iliyan Iliev and Dr. Irina Leonardi.