Could a Fungus Cause Crohn’s Disease?

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Poop-based scientific breakthroughs are coming through on the regular these days. The latest: Researchers found unique fungal-bacterial relationships in fecal samples from people with Crohn’s disease. In their report, published September 20 in the open access journal mBio [PDF], they say fungus may even play a role in the disease’s development.

For those of you unacquainted with Crohn’s disease, here’s a primer: It’s terrible. Crohn’s is a chronic illness of the digestive tract that can cause inflammation, pain, diarrhea, cramps, fatigue, malnutrition, and weight loss. Doctors aren’t sure what causes it, which means they can only try to ease a patient’s symptoms. Its triggers can vary from person to person; for many, food is a prime culprit, but, as the National Institute of Diabetes and Digestive and Kidney Diseases helpfully points out, “Some research suggests that stress, including the stress of living with Crohn’s disease, can make symptoms worse.”

So identifying the root of the problem could do a whole lot of people (at least half a million in the U.S. alone) a whole lot of good. Because Crohn’s lives in the digestive tract, the microbiome, or community of microbes living in the body, has been a natural focus of research. Most studies to date have focused on the bacterial aspects of the microbiome, but there’s a lot more going on in there—including fungus.

An international team of researchers collected and tested fecal samples from 69 people in 22 French and Belgian families. Twenty of the participants had Crohn’s; 28 were the non-diagnosed family members they shared a home with; and the remaining 21 were healthy participants living in the same region.

The microbial communities of participants with Crohn’s had a distinct profile all their own. Not only did people with Crohn’s have higher levels of two potentially pathogenic bacteria (Escherichia coli and Serratia marcescens) and one fungus (Candida tropicalis), but the three species also seemed to be interacting more intensely in their guts. The triad appeared to be working together to produce a slimy film on the intestines—the same film known to trigger Crohn’s-related inflammation.

The study authors are careful to point out that C. tropicalis—a yeast that is a normal part of our gut flora yet associated with several diseases [PDF]—may be a cause of Crohn’s, but it’s certainly not the only cause.

Mahmoud A. Ghannoum is a senior author on the paper and director of the Center for Medical Mycology at Case Western Reserve University and University Hospitals Case Medical Center. He says his team’s research could help identify the hidden causes of Crohn’s.

“Equally important,” he says in a press statement, “it can result in a new generation of treatments, including medications and probiotics, which hold the potential for making qualitative and quantitative differences in the lives of people suffering from Crohn's."

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