Common yeast can cause problems for patients with Crohn’s disease

A fungal yeast found in cheese and other foods can wreak havoc in the intestines of people with Crohn’s disease, new findings show. In one to study published Thursday, researchers found evidence that patients with Crohn’s disease are more likely to carry this yeast than people without the disease, and that this yeast is linked to the slow-healing intestinal wounds that patients tend to have. . If valid, the results could lead to new treatments and preventive measures for the chronic and painful disease.

Crohn’s disease is one of the most well-known versions of inflammatory bowel disease (IBD). There is no clear cause for IBD, but genetics and a faulty immune system are suspected to play an important role. Patients present with a wide range of mainly gastrointestinal symptoms caused by chronic inflammation of the intestine, which come and go as disease flare-ups. These include diarrhea, fever, severe cramps, and weight loss. Although there are drugs that can manage the symptoms, as well as diets to help people avoid possible triggers for an episode, few people experience prolonged remission.

Researchers at the Cleveland Clinic and elsewhere have been studying Crohn’s disease for some time now in hopes of finding something that might help explain how and why the gut is so damaged in these patients. Their new research, published in Science, indicates a possible culprit: a fungus called Debaryomyces hansenii.

Scientists studied mice designed to develop Crohn-like symptoms as well as biopsied samples of intestinal tissue from people diagnosed with Crohn’s disease. 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 non-inflamed tissue from patients with Crohn’s disease.

They found the fungi in all seven samples taken from a group of Crohn’s disease patients, for example, but only in one of 10 healthy controls used for comparison. They also found evidence that this yeast was directly linked to the slow healing of intestinal wounds in mice. And when they took samples of the fungus 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 mice received antifungal treatment.

All of the results combined, the researchers say, meet Koch’s postulates, a test that scientists use to prove that a specific microbe causes a specific set of symptoms. In other words, it suggests that D. hansenii is not only a harmless bystander found in the guts of these patients, but an active source of trouble. At this point, it’s unclear how patients might be exposed to the fungi, or if foods high in yeast, like cheese, might be a source.

“We propose that D. hansenii inhibits repair of ulcers in the inner lining of the intestine in patients with Crohn’s disease, ”said study author Thaddeus Stappenbeck, chair of the Department of Inflammation and Immunity at the Cleveland Clinic Lerner Research Institute, to Gizmodo in an email. “This feature is a hallmark of many Crohn’s disease patients with moderate to severe disease.”

According to their current theory, the fungal infection does not cause Crohn’s disease itself, Stappenbeck added. On the contrary, it “perpetuates the disease which has already been initiated”.

The results are always based on a small group of patients and animal research, so they should not be taken as definitive proof of the team’s theory. And even if they are right, Crohn’s disease and IBD in general will remain complex disease with symptoms that cannot be fully explained by a single microbe. In the mice they studied, for example, fungal overgrowth only occurred after antibiotics were administered to the mice. Other research has sharp antibiotics as a possible risk factor for Crohn’s disease because they can disrupt the delicate microscopic environment in our gut, called the gut microbiome.

While future research continues to show a strong link between Crohn’s disease and D. hanseniihowever, it could lead to important new treatments and strategies for managing the disease. “For patients with D. hansenii in their ulcers, we are planning to test antifungal drugs, ”Stappenbeck said. “We hope this would also stimulate the development of antifungals with fewer side effects.”

Another area of ​​research could be to target D. hansenii seems to cause intestinal inflammation in the body, through a protein called CC5 produced by certain immune cells. And since yeast is commonly found in cheese and other processed foods, it might be beneficial for patients in general to avoid these foods, the researchers say. The team also plans to continue to study how yeast interacts with the gut microbiome and the immune system of people with Crohn’s disease.

This article has been updated with comments from one of the study authors.