Flavonoids Coupled With Specific Gut Microbes May Prevent Severe Flu

Microbes that live in the gut don’t just digest food. They also have far-reaching effects on the immune system. Now, a new study shows that a particular gut microbe can prevent severe flu infections in mice, likely by breaking down naturally occurring compounds — called flavonoids — commonly found in foods such as black tea, red wine and blueberries.

The research, conducted in mice by scientists at Washington University School of Medicine in St. Louis, also indicates that this strategy is effective in staving off severe damage from flu when the interaction occurs prior to infection with the influenza virus. This work also could help explain the wide variation in human responses to influenza infection.

The study is published in the journal Science.

“For years, flavonoids have been thought to have protective properties that help regulate the immune system to fight infections,” said first author Ashley L. Steed, MD, PhD, an instructor in pediatrics who treats intensive care patients at St. Louis Children’s Hospital. “Flavonoids are common in our diets, so an important implication of our study is that it’s possible flavonoids work with gut microbes to protect us from flu and other viral infections. Obviously, we need to learn more, but our results are intriguing.”

“It’s not only having a diet rich in flavonoids, our results show you also need the right microbes in the intestine to use those flavonoids to control the immune response,” said the study’s senior author, Thaddeus S. Stappenbeck, MD, PhD, the Conan Professor of Pathology & Immunology. “We were able to identify at least one type of bacteria that uses these dietary compounds to boost interferon, a signaling molecule that aids the immune response. This prevented influenza-related lung damage in the mice. It is this kind of damage that often causes significant complications such as pneumonia in people.”
As part of the study, the researchers screened human gut microbes looking for one that metabolized flavonoids. Stappenbeck and Steed identified one such microbe that they suspected might protect against flu damage. The microbe, called Clostridium orbiscindens, degrades flavonoids to produce a metabolite that enhances interferon signaling.

Read the entire article at Infection Control Today here.