Gut Microbes and Flavonoids Can Help Fight Influenza

Highlights

• An average of 113 children die from influenza each year in the U.S.
• Clostridium orbiscindens is a gut microbe that can prevent severe flu infections
• Metabolite called desaminotyrosine (DAT) prevents flu infection and protects the immune system

A particular gut microbe was found to prevent severe flu infections by breaking down naturally occurring compounds called flavonoids, reveals a new study. Flavonoids are most commonly found in foods like black tea, red wine and blueberries.// The research team reported that this approach was found to be effective in fighting against severe damage caused due to flu, particularly when the interaction occurs before the infection with the influenza virus. The study also helps in explaining the wide range of human responses to influenza infection.

The study was published in the journal Science.

Importance of Flavonoids in the Diet

Microbes that live in the gut digest food and also have widely applicable effects on the immune system. Ashley L. Steed, MD, PhD, first author, and an instructor in pediatrics who treats intensive care patients at St. Louis Children's Hospital said that for years, flavonoids were thought to have protective properties i.e., to help in regulating the immune system to fight against infections.

She also said: "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."

Influenza is an infectious disease that is common and sometimes is a deadly viral infection that affects the upper respiratory tract. Influenza is characterized by fever, cough and body aches.

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People who are most prone to serious flu complications are older adults, pregnant women, young children, and also people with chronic health illnesses like asthma and heart disease .

In the U.S, an average of 113 children have died from influenza each year since 2004, according to the Centers for Disease Control and Prevention.

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The World Health Organization (WHO) estimates that there are about 250,000 to 500,000 flu-related deaths annually, around the world.

Previous studies show that the gut microbiome were found to be important in protecting against severe influenza infections. However, in this study, the research team aimed to identify those exact gut microbes which might provide this protection.

In addition, potential health benefits associated with foods loaded with flavonoids are being explored by nutritionists for years.

Thaddeus S. Stappenbeck, MD, PhD, the Conan Professor of Pathology & Immunology sais that it’s not only about having a diet which is rich in flavonoids, but to have the right microbes in the intestine, which aid these flavonoids in controlling the immune response.

He also said that the research team was able to identify at least one type of bacteria which could use these dietary compounds to boost interferon. This was found to be a signaling molecule that helps in the immune response and also prevents influenza-related lung damage in the mice. However, in people it is this kind of damage that leads to various complications like pneumonia.

Role of Microbes and DAT in the Gut

In this study, the research team screened human gut microbes looking for that one type of bacteria which metabolizes flavonoids. One such microbe has been identified by Stappenbeck and Steed.. They suspected that it might protect against flu damage.

Clostridium orbiscindens is the microbe that degrades flavonoids to produce a metabolite called desaminotyrosine or otherwise known as DAT that enhances the interferon signaling.

The research team administered DAT to mice and then infected them with influenza. They found that the mice experienced far less lung damage, when compared to the mice that were not treated with DAT.

Though the lungs of DAT-treated mice did not have as much flu damage as the non-treated mice, it was found that their levels of viral infection were identical to those mice that did not receive the treatment, according to the research team of this study.

Stappenbeck said that the infections were primarily the same. The flu infection was not prevented by the microbes and DAT, as the mice still had the virus. But, it was the DAT that kept the immune system from harming the lung tissue.

This finding of the study is very important, as annual flu vaccines weren't always efficient in preventing the infections. It might be possible to keep people from getting sick with DAT, just in case they become infected.

Steed said: “This strategy doesn't target the virus. Instead, it targets the immune response to the virus. That could be valuable because there are challenges with therapies and vaccines that target the virus due to changes in the influenza virus that occur over time."

Further research is needed to identify other gut microbes which may use flavonoids to influence the immune system and also to explore various possible ways to boost the levels of these bacteria in people, whose intestines are not adequately colonized.

The research team suggest people to drink black tea and to consume foods rich in flavonoids before the next flu season begins.

Reference

1. Ashley L. Steed, George P. Christophi, Gerard E. Kaiko, Lulu Sun, Victoria M. Goodwin, Umang Jain, Ekaterina Esaulova, Maxim N. Artyomov, David J. Morales, Michael J. Holtzman, Adrianus C. M. Boon, Deborah J. Lenschow, Thaddeus S. Stappenbeck. The microbial metabolite desaminotyrosine protects from influenza through type I interferon. Science (2017). DOI: 10.1126/science.aam5336

Source-Medindia