A fungal yeast found in cheese and other foods can wreak havoc on the bowels of people with Crohn’s disease, according to new findings. In a study published on Thursday, researchers found evidence that Crohn’s patients are more likely to carry this yeast than people without the disease, and that this yeast is linked to slow-healing intestinal wounds that patients tend to to have. If valid, the results can lead to new treatments and preventive measures for the chronic and painful condition.
Crohn’s is one of the best known versions of intestinal disease (IBD). There is no clear cause for IBD, but genetics and a defective immune system are suspected to play an important role. Patients have a wide range of symptoms, mainly gastrointestinal, caused by chronic inflammation of the intestine, which come and go as outbreaks of the disease. This includes diarrhea, fever, severe cramps and weight loss. Although there are drugs that can control symptoms, along with diets to help people avoid possible triggers of an episode, few patients have sustained remission.
Researchers at the Cleveland Clinic and elsewhere have been studying Crohn’s disease for some time, hoping to find something that can help explain how and why the gut gets so damaged in these patients. Your new research, Published in science, points to a possible culprit: a fungus called Debaryomyces hansenii.
The scientists studied mice that were made to develop Crohn-like symptoms, as well as biopsy samples of intestinal tissue from people diagnosed with Crohn’s. In both groups, they found an abundance of D. hansenii around injured or inflamed tissue, but not in samples taken from healthy people or in the non-inflamed tissue of Crohn’s patients.
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They found fungi in all seven samples taken from a group of Crohn’s patients, for example, but in only one of the 10 healthy controls used as a comparison. They also found evidence that this yeast was directly linked to the slow healing of intestinal wounds in rats. And when they took samples of fungi from a Crohn’s patient or sick mice and gave them to a new group of healthy mice, the mice’s ability to heal intestinal wounds worsened. This effect was then reversed when the rats received antifungal treatment.
All the combined findings, the researchers say, meet Koch’s postulates, a criterion that scientists use to prove that a specific microbe is causing a specific set of symptoms. In other words, it suggests that D. hansenii it is not just a harmless spectator found in the bowels of these patients, but an active source of problems. At the moment, it is not known how patients can be exposed to fungi, or whether foods rich in yeast, such as cheese, may be one of the sources.
“We propose that D. hansenii inhibits the repair of ulcers in the inner lining of the intestine in patients with Crohn’s disease, ”study author Thaddeus Stappenbeck, president of the Department of Inflammation and Immunity at the Cleveland Lerner Clinical Research Institute, told Gizmodo. “This feature is a hallmark of many Crohn’s patients with moderate to severe illness.”
According to current theory, fungal infection does not cause Crohn’s disease itself, added Stappenbeck. Instead, it “perpetuates the disease that has already started”.
The findings are still based on a small group of patients and animal research, so they should not be seen as definitive proof of the team’s theory. And even if they’re right, Crohn and IBD in general will remain a complex disease with symptoms that cannot be explained entirely by a single microbe. In the mice they studied, for example, the overgrowth of the fungus only happened after the mice were given antibiotics. Another research has pointed antibiotics as a possible risk factor for Crohn’s disease, since they can disturb the delicate microscopic environment of our intestine, called the intestinal microbiome.
If future research continues to show a strong link between Crohn and D. hanseniihowever, it can lead to new treatments and important strategies to control the disease. “For patients with D. hansenii on your ulcers, we plan to test antifungal drugs, ”said Stappenbeck. “We hope that this will also encourage the development of antifungals with fewer side effects.”
Another area of research may involve defining how D. hansenii it appears to cause intestinal inflammation in the body, through a protein called CC5, produced by some cells of the immune system. And since yeast is commonly found in cheeses and other processed foods, it may be worth it for patients in general to avoid these foods, the researchers say. The team also plans to continue studying how yeast interacts with the intestinal microbiome and immune system of people with Crohn’s.
This article was updated with comments from one of the study’s authors.