Microflora helps fight the flu

Intestinal microbes have turned flavonoids into an antiviral drug

Daria Spasskaya, N+1

The staff of the University of Washington Medical School showed how the intestinal microbiota can reduce inflammation in the lungs during infection with the flu virus. The metabolite formed with the participation of the microorganism Clostridium orbiscindens stimulates an interferon-dependent immune response that protects the host from complications of infection. Perhaps a diet enriched with flavonoids will help to enhance the production of the metabolite by microbes. The results of the research are published in the journal Science. An employee of St. Petersburg ITMO University also took part in the work.

Interferons of the first type are signaling molecules, the production of which is activated during viral infection and leads to suppression of the synthesis of viral proteins. In particular, the interferon response is triggered when infected with the influenza virus.

Preliminary studies in mice have shown that the intestinal microbiota can regulate the severity of infection, including through the interferon pathway. Sterile mice, that is, devoid of microorganisms inhabiting the intestines, are more likely to die from influenza as a result of complications, including pneumonia.

The researchers suggested that the gut microbial community produces metabolites that can stimulate an interferon response in the body. To identify these substances, the authors of the work checked a library of 84 known molecules produced by microbes in a reporter system on cells. The most suitable candidate turned out to be deaminothyrosine (DAT) – a product of amino acid and flavonoid metabolism. Intestinal bacteria can metabolize these components found in food to form DATES.

The authors were convinced that the feces of healthy mice do contain significant amounts of DATES. If the mice were fed antibiotics that destroy the intestinal microflora, the production of DATES stopped. If mice were given DAT along with food and infected with the influenza virus, an interferon response was indeed stimulated in their lungs, and survival was higher than in the control group. A study of the lungs of sick mice showed that an increased interferon response leads to suppression of viral transcription and increased phagocytic activity in tissues.

The search for a microorganism that effectively produces DAT in the human microbiota pointed to the microbe Clostridium orbiscindens. Infection of sterile mice with it saved the animals from complications with influenza.

Thus, the authors of the work found that one of the microorganisms of the intestinal community is able to metabolize food components with the formation of a substance that stimulates an antiviral response. The study demonstrated that this substance (deaminotyrosine), when ingested, effectively protects animals from flu complications. Scientists have not tested which flavonoids most strongly stimulate the formation of DATES, since this is a very extensive class of compounds. In addition to indirect antiviral activity, flavonoids (polyphenols) have antioxidant properties.

The work also explains why some antibiotics (in particular, vancomycin, neomycin and ampicillin) lead to a deterioration in the condition of patients with influenza. Apparently, they suppress the natural antiviral defense, which is carried out by the intestinal microbiota.

In the same issue of the journal Science, a second article from the University of Washington was published on microbiota. Scientists have shown that the microorganism Lactobacillus reuteri regulates the immune response in the intestinal epithelium with the help of amino acid tryptophan metabolites and reduces inflammation.

Portal "Eternal youth" http://vechnayamolodost.ru  28.08.2017