The fungus Candida tropicalis may trigger gut inflammation and worsen Crohn’s disease, according to results of a study presented at this year’s Digestive Disease Week, held recently in Chicago.

The hallmark of Crohn’s disease is gut inflammation, or colitis. Colitis is thought to be triggered when the body’s immune system responds to an infection, but also ends up attacking cells that compose the intestinal tract.

Now researchers think that one possible cause of gut inflammation may be an infection by Candida tropicalis.

“The type of microorganisms that live in our intestine, our microbiome, has been shown to be a key element for triggering Crohn’s disease,” Luca Di Martino, PhD, said in a press release. Di Martino is a  researcher at the Digestive Health Research Institute at Case Western Reserve University School of Medicine. “Recent studies have shown that the abundance of the fungus Candida tropicalis is significantly higher in the intestine of Crohn’s disease patients compared to healthy people.”

To investigate the potential negative effects triggered by the presence of this fungus, researchers compared mice infected with Candida tropicalis to non-infected mice. They observed that infected mice had severe symptoms of Crohn’s disease compared to the others. Indeed, they presented 4.5 times higher expression of IFN-γ, an inflammatory molecule associated with colitis, than non-infected mice.

These results support the idea that the presence of Candida tropicalis renders the gut more vulnerable to develop inflammation. The team believes that the fungus induces inflammation by promoting the growth and activity of gut bacteria.

“We found that high levels of C. tropicalis increases the abundance of harmful proteobacteria in the intestine, such as E. coli, disrupting the normal balance of the gut bacteria and creating a dysbiosis, a key element that triggers intestinal inflammation,” Di Martino said.

“The most exciting discovery was that in the infected mice there was a significantly higher abundance of proteobacteria, the same type of deleterious bacteria found increased in Crohn’s patients,” Di Martino said. “This confirmed that the presence and the abundance of fungi in the intestine have the ability to modify the bacteria living in our intestine, leading to a dysbiosis [microbial imbalance] which will eventually trigger an inflammatory syndrome.”

Researchers want to investigate whether treating infected mice with anti-fungal medication can eliminate C. tropicalis and reduce the symptoms associated with gut inflammation. If successful, and if the team is able to validate the impact of this fungus in humans, the study may help design new targeted therapies to treat patients with Crohn’s disease.

The abstract of this study, “Infection with the Fungus Candida Tropicalis Significantly Increases the Severity of Colitis in C57BL/6 Mice,” was published in Gastroenterology.