Individual Candida albicans yeast strains in the human gut are as different from each other as the humans that carry them, and some C. albicans strains may damage the gut of patients with inflammatory bowel disease (IBD), according to a new study from researchers at Weill Cornell Medicine. The findings suggest a possible way to tailor treatments to individual patients in the future.
The researchers, who report their findings March 16 in Nature, used an array of techniques to study strains, or genetic variants, of Candida from the colons of people with or without ulcerative colitis, a chronic, relapsing and remitting inflammatory disorder of the colon and rectum and one of the main forms of IBD. They found that certain strains, which they call “high-damaging,” produce a potent toxin called candidalysin that damages immune cells.
Dr. Iliyan Iliev
“Such strains retained their “high-damaging” properties when they were removed from the patient’s gut and triggered pro-inflammatory immunity when colonized in mice, replicating certain disease hallmarks,” said senior author Dr. Iliyan Iliev, an associate professor of immunology in medicine in the Division of Gastroenterology and Hepatology and a scientist in the Jill Roberts Institute for Research in Inflammatory Bowel Disease at Weill Cornell Medicine.
IBD affects approximately 3.1 million people in the United States and can greatly impair patients’ quality of life. Such patients rely on a handful of available therapies, but treatments may not always be effective. The new study has suggested one reason steroids, a commonly used treatment, may not work; treating mice with the drug to suppress intestinal inflammation failed in the presence of “high-damaging” C. albicans strains.
“Our findings suggest that C. albicans strains do not cause spontaneous intestinal inflammation in a host with intact immunity,” Dr. Iliev said. “But they do expand in the intestines when inflammation is present and can be a factor that influences response to therapy in our models and perhaps in patients.”
Most studies of the human microbiome in healthy individuals and those with IBD have focused on bacteria and viruses, but recent research by Dr. Iliev and others has illuminated the contributions of fungi to the effects of microbes on humans and mice. They have found that intestinal fungi play an important role in regulating immunity at surfaces exposed to the outside, such as the intestines and lungs, due to their potent immune-stimulating characteristics. While the collective community of fungi in the body, known as the mycobiota, has been linked to several diseases, including IBD, researchers previously had not understood the mechanisms by which the mycobiota contribute to inflammation in the gut. To continue reading, click here.