Bacterial metabolites regulate immune system; may reduce IBD

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Harvard School of Public Health (HSPH) researchers have discovered that chemicals generated by bacteria in the colon help important immune cells known as Tregs in the colon grow and function well. The researchers also found that these bacterial metabolites reduced colitis in mice with inflammatory bowel disease (IBD), a chronic disease of the intestines that afflicts over two million people worldwide.

“Increasingly, scientists, physicians, and the public are recognizing that the gut microbiota, the microbes that live within our intestines, shape our health and wellbeing in innumerable ways. We’ve identified that an abundantly produced microbial metabolite shapes the immune response,” said Wendy Garrett, senior author and assistant professor of immunology and infectious diseases at HSPH.

The study was published online July 4, 2013 and will appear in the August 2, 2013 print edition of the journal Science.

Researchers have long suspected a link between gut microbes and immune-related diseases, such as obesity, allergies, IBD, and colon cancer. Identifying the specific link, however, has been difficult.

Garrett and lead author Patrick Smith, who was a postdoctoral fellow at HSPH at the time of the study, and colleagues focused on the role of Tregs, which are regulatory T cells in the large intestine. Tregs help people live peacefully with their gut bacteria and enable a wide range of foods to be digested.