Microbial transplants require key T cells for success

Findings that certain immune cells are needed for fecal microbiota transplant success against C. difficile infections may be a clue to making this promising treatment work more broadly.

Scientists have known for more than a decade that “good bacteria” from healthy intestines can treat and ward off potentially deadly intestinal infections by Clostridium difficile bacteria. Now, researchers at the Perelman School of Medicine have discovered that immune cells called Treg cells are crucial for the success of these microbial transplants.

Three petri dishes with different colored substances for microscopic views of bacteria.

The findings, published in Nature Communications, hint that boosting the activity of Treg cells may be a way to improve the effectiveness of microbial transplants for C. difficile infections. Modulating the activities of key immune cells may also turn out to be a good strategy in other diseases for which microbial transplants have been considered, including cancers, obesity, inflammatory bowel disease, and diabetes.

“With this discovery we may have identified a general law that the immune system needs to be in a certain state for these microbial transplants to work,” says Michael Abt, an assistant professor of microbiology.

C. difficile infection of the large intestine is the most common hospital-acquired infection in the United States. It often afflicts elderly people following antibiotic treatment that disrupts their normal intestinal microbe population. Although there are antibiotics that can treat “C. diff,” the continued disruption of gut microbiota and the ability of C. diff to form hardy spores means that recurrence rates are high. There are an estimated half-million cases of C. diff infection per year, of which tens of thousands are fatal.

Transplanting healthy gut bacteria from volunteers, known as microbial transplantation, or fecal microbiota transplantation—is now a proven treatment for treating C. diff, although in 10-20% of cases it doesn’t work, and scientists haven’t really understood these failures.

Read more at Penn Medicine News.