Research on ‘Good Bacteria’ Garners Prize for UR Physician

July 01, 2011

A physician and fellow at the University of Rochester Medical Center has been honored for her research on probiotics – bacteria that promote human health.

Sonia Yoon, M.D., a physician who did research in the laboratory of Jun Sun, Ph.D., in the Gastroenterology and Hepatology Division of the Department of Medicine, was awarded third place in the Probiotics Challenge at the annual meeting of the American Gastroenterological Association in Chicago recently. The prize includes a $2,500 award.

Yoon’s work is designed to help scientists understand why probiotics sometimes help patients with inflammatory bowel diseases such as Crohn’s disease or ulceractive colitis, and why they sometimes don’t. Probiotics are sometimes used to treat these conditions, as well as other conditions like diarrhea and complications from surgery, but how they work is unclear.

Yoon and colleagues, including Sun and post-doctoral associate Shaoping Wu, Ph.D., have found that probiotics may work through the vitamin D receptor. In the work presented in Chicago, Yoon found that when probiotics are effective, the vitamin D receptor is more plentiful, and when the vitamin D receptor is lacking, probiotics might actually do more harm than good.

The work comes at a time when the effects of vitamin D are under increasing scrutiny. Scientists have associated vitamin D and the receptor with many types of cancer, as well as osteoporosis, heart disease, diabetes, inflammatory bowel disease, and infection. Sun, who has shown that the vitamin D receptor is a key player governing the effects of bacteria in the gut flora, notes that the receptor itself is crucial for the molecule to have an effect in the body.

The latest research is part of Yoon’s training for a career treating people with conditions of the digestive tract. The training includes research, and Yoon chose to work in Sun’s laboratory based in part on Yoon’s exposure to a medical procedure that may sound implausible at first, yet provides relief to some patients.

During her medical residency, Yoon witnessed the relief that some patients with severe gastrointestinal symptoms received from a “stool transplant.” In that procedure, feces from a healthy donor are transplanted into the colon of a person with a condition such as severe diarrhea caused by an infection with Clostridium difficile.

While the procedure on its face sounds almost preposterous, it provides relief to some patients. One factor that may come into play is the “gut flora” – the collection of bacteria and other organisms that reside in our digestive tract.

The human intestines and stomach teem with more than 500 species of bacteria comprising more than 100 trillion microbial cells. The balance of bacteria, both good and bad, is crucial; that sensitive balance is more likely to be out of whack in patients with diseases like colon cancer, liver disease, obesity, and ulcerative colitis. A stool transplant helps restore a healthy balance.

Sun is a world expert on that balance and the factors that affect it. She has shown that bacteria found in the human intestine affect molecular signals known to contribute to inflammatory response and cell growth, and she has shown how bacteria can affect molecular signals known to contribute to colorectal cancer. 

“I am very proud, not only of Sonia but also of the other scientists training in my laboratory,” said Sun. “They work very hard. Our hope is that our research will one day improve the lives of patients around the world who suffer the consequences of diseases like colon cancer and Crohn’s disease,” said Sun, who is assistant professor in the Gastroenterology and Hepatology Division of the Department of Medicine.