News

Antibodies Help Keep Harmful Forms of Gut Fungi in Check

Antibody protection against harmful forms of fungi in the gut may be disrupted in some patients with Crohn’s disease—a condition caused by chronic inflammation in the bowel—according to a new study by Weill Cornell Medicine investigators.

Previous studies have shown that the immune system plays a key role in maintaining a healthy balance of gut bacteria. In the new study, published Nov. 22 in Nature Microbiology, senior author Dr. Iliyan Iliev, associate professor of immunology in medicine in the Division of Gastroenterology and Hepatology, and his team at Weill Cornell Medicine investigated if it might also play a role in managing gut fungi. Unlike bacteria, fungi can change their shape in response to environmental conditions, and certain forms are harmful to humans. In particular, a type of fungus called Candida albicans transforms from a yeast form that is not pathogenic to a form that produces long, branched structures called hyphae, which can invade tissues and cause damage.

two men posing for a photo

(From left) Dr. Iliyan Iliev and Itai Doron.

The investigators found that antibodies that are secreted in the gut help control the pathogenesis of Candida albicans in healthy individuals and that this protective mechanism may be disabled in people with Crohn’s disease, causing a harmful overgrowth of the pathogenic form of the fungus. An intestinal overabundance of Candida albicans is associated with inflammatory bowel disease and several other conditions that directly or indirectly affect the gastrointestinal tract.

“We found that antibodies secreted in the gut are involved in maintaining specific intestinal fungi such as C. albicans in its benign, so-called commensal form,” said Dr. Iliev, who is also a scientist in the Jill Roberts Institute for Research in Inflammatory Bowel Disease at Weill Cornell Medicine. “This process is interrupted in patients with Crohn’s disease.” To read more, click here.

Antibody Protection against Gut Fungi May Be Disrupted in Crohn’s Disease

Image Source: ChrisChrisW/Getty Images

Inflammatory bowel disease (IBD), a family of autoimmune diseases of the gut, has set researchers on a hunt to understand which microbes are responsible for launching the immune system into overdrive. Previous studies have demonstrated and pointed to gut fungus as a culprit in the inflammatory bowel disease, Crohn’s disease. Now, Weill Cornell Medicine researchers report that antibody protection against harmful forms of fungi in the gut may be disrupted in some patients with Crohn’s disease.

The findings are published in the journal Nature Microbiology, in a paper titled, “Mycobiota-induced IgA antibodies regulate fungal commensalism in the gut and are dysregulated in Crohn’s disease.”

“Secretory immunoglobulin A (sIgA) plays an important role in gut barrier protection by shaping the resident microbiota community, restricting the growth of bacterial pathogens and enhancing host protective immunity via immunological exclusion,” the researchers wrote. “Here, we found that a portion of the microbiota-driven sIgA response is induced by and directed towards intestinal fungi.”

Iliyan Iliev, PhD, associate professor of immunology in medicine in the division of gastroenterology and hepatology, and his team investigated if the immune system plays a key role in managing gut fungi.

The team discovered that antibodies that are secreted in the gut help control the pathogenesis of Candida albicans in healthy individuals and that this protective mechanism may be disabled in people with Crohn’s disease.

“We found that antibodies secreted in the gut are involved in maintaining specific intestinal fungi such as C. albicans in its benign, so-called commensal form,” said Iliev, who is also a scientist in the Jill Roberts Institute for Research in Inflammatory Bowel Disease at Weill Cornell Medicine. “This process is interrupted in patients with Crohn’s disease.” To read more, click here.

A common fungus sets the stage for successful fecal microbiota transplantation in people with ulcerative colitis

A recent study found that high levels of a common fungus in the gut could signal whether a microbe-based treatment would be successful for people with ulcerative colitis. Changes or disruptions in the gut’s microbiome—the community of bacteria, viruses, and fungi that naturally inhabit the intestines—have been implicated in inflammatory bowel diseases like ulcerative colitis. One treatment that researchers are investigating is fecal microbiota transplantation (FMT), whereby a sample containing gut microbes from a healthy donor is introduced into a person with colitis to help reestablish a more functional gut microbiome. While FMT has proven to be a successful therapy for people with Clostridioides difficile (C. diff) bacterial infections, with over 90 percent of people cured after a single treatment, FMT is less successful for people with ulcerative colitis: in a recent clinical trial, less than half the participants with colitis experienced remission after FMT. Knowing why the treatment works only in some people is important, because it would allow health care providers to predict which individuals with ulcerative colitis would benefit from FMT as opposed to another treatment strategy. One possibility is that FMT’s success may be dependent upon the makeup of the recipient’s microbiome. For example, FMT is less likely to succeed as a C. diff treatment for people who have high levels of Candida, a type of fungus found in the guts of nearly everyone. To read more, click here.

Weill Cornell Medicine Iliev Lab 413 E 69th Street, BB-752 New York, NY 10021 Phone: (646) 962-7236