Fungus found in foods can infect sites of intestinal damage, study

Foodborne fungi, i.e., yeasts and molds, can cause severe damage to human health. They produce toxins that cause diseases. This foodborne fungus gets into inflamed, injured tissue and causes harm.  

In healthy people, such damage typically heals in a day or two. But in people with Crohn’s disease, the wounds fester, causing abdominal pain, bleeding, diarrhea, and other unpleasant symptoms. 

A recent study by the Washington University School of Medicine in St. Louis and the Cleveland Clinic has discovered that a fungus found in foods such as cheese and processed meats can infect sites of intestinal damage in mice and people with Crohn’s and prevent healing. However, it was found that the antifungal medication eliminates the fungus and allows the wounds to heal. 

The study offers a potent new approach to improving intestinal wound healing and reducing symptoms of Crohn’s disease. 

As scientists noted, the study does not suggest that people should stop eating cheese and processed meat. Scientists are looking forward to finding a correlation between diet and the abundance of this fungus in the intestine. If so, it is possible dietary modulation could lower the fungus levels and thereby reduce symptoms of Crohn’s disease. 

Crohn’s disease is a type of inflammatory bowel disease (IBD). It causes inflammation of your digestive tract. It is primarily treated with immunosuppressive medications. Crohn’s patients endure repeated cycles of gastrointestinal symptom flare-ups and remission. Their digestive tracts are dotted with inflamed, open sores that can persist for several days during a flare. 

In this study, scientists also aimed to understand why intestinal ulcers take so long to heal. For this, they studied mice with the injured intestine. By sequencing microbial DNA at the injury site, they discovered that the fungus Debaryomyces hansenii was abundant in wounds but not in uninjured parts of the intestine. 

First author Umang Jain, Ph.D., an instructor in pathology & immunology at the School of Medicine, said, “People acquire the fungus through their food and drink. D. hansenii is commonly found in all kinds of cheeses, as well as sausage, beer, wine, and other fermented foods.” 

Further experiments revealed that introducing fungus to mice with injured intestine diminishes the healing process. On the other hand, eliminating D. hansenii with the antifungal drug amphotericin B optimizes the healing process. 

In their study, scientists noticed that people with Crohn’s disease and mice carry the same fungus. They came to know this after examining seven people with Crohn’s disease and ten healthy people. 

All seven of the patients harbored the fungus in their gut tissue compared with only one of the healthy people. In a separate analysis of 10 Crohn’s patients involving tissue samples of both inflamed and uninflamed areas of the gut, the scientists found the fungus in samples from all of the patients but only at injury sites and inflammation. 

Jain said, “If you look at stool samples from healthy people, this fungus is highly abundant. It goes into your body and comes out again. But people with Crohn’s disease have a defect in the intestinal barrier that enables the fungus to get into the tissue and survive there. And then it makes itself at home in ulcers and sites of inflammation and prevents those areas from healing.” 

It was found that the drug amphotericin B was effective at eliminating the fungus in mouse studies. Although it is not widely used in people because it can only be given intravenously. 

Jain said, “Crohn’s disease is fundamentally an inflammatory disease, so even if we figured out how to improve wound healing, we wouldn’t be curing the disease. But in people with Crohn’s, impaired wound healing causes a lot of suffering. If we can show that depleting this fungus in people’s bodies – either by dietary changes or with antifungal medications – could improve wound healing, then it may affect the quality of life in ways that we’ve not been able to do with more traditional approaches.” 

Journal Reference:

1. Jain U et al. Debaryomyces is enriched in Crohn’s disease intestinal tissue and impairs healing in mice. Science, 2021. DOI: 10.1126/science.abd0919