Gut microbiota influences severity of respiratory viral infection: Study |  Health

Gut microbiota influences severity of respiratory viral infection: Study | Health

According to researchers from Georgia State University’s Center for Translational Antiviral Research and the Institute for Biomedical Sciences, the composition of the gut microbiota determines how vulnerable mice are to respiratory virus infections and the severity of those infections.

Gut microbiome influences severity of respiratory viral infection: Study (AFP/Istock)

The findings, published in the journal Cell Host & Microbe, report that segmented nematode bacteria, a bacterial species found in the intestines, protected mice from influenza virus infection when these bacteria were either acquired naturally or administered.

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This protection against infection also applies to respiratory syncytial virus (RSV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus that causes COVID-19. To maintain this protection, the study noted that the fragmented filamentous bacteria required immune system cells in the lungs called basic resident alveolar macrophages.

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In this study, the researchers explored how differences in specific microbial species can affect the outcomes of respiratory virus infections and how they might do so, which has not been well defined before. They studied mice with distinct microbiome differences and mice that differed only in the presence or absence of segmented nematode bacteria. Virus titers in the lung were measured several days after infection and varied significantly depending on the nature of the microbiome of the different animal groups.

“These findings reveal complex interactions that mechanistically link gut microbiota to alveolar macrophage functionality and the severity of respiratory viral infection,” said Dr. Andrew Gewirtz, co-senior author of the study and Regents Professor in the Institute of Biomedicine. Science at Georgia State.

The study found that in fragmented nematode bacteria-negative mice, the primary resident alveolar macrophages were rapidly depleted as respiratory virus infection progressed. However, in mice colonized with segmental filamentous bacteria, primary resident alveolar macrophages were modified to resist exhaustion of influenza virus infection and inflammasome signaling.

Primary resident alveolar macrophages inactivated the influenza virus, largely by activating a component of the immune system referred to as the complement system.

“We find it remarkable that the presence of a single common bacterial species, among the thousands of different microbial species inhabiting the mouse gut, had such strong effects in models of respiratory virus infection, and that such effects were largely due to the reprogramming of essentially resident alveolar macrophages,” said Dr. Richard Plemper, co-senior author of the study, Regents Professor and director of the Center for Translational Antiviral Research at Georgia State. “If applicable to human infections, these findings will have important implications for future risk assessment of a patient to progress to severe disease.”

“We find it highly unlikely that segmented filamentous bacteria are the only gut microbe that can influence alveolar macrophage phenotype and, consequently, susceptibility to respiratory virus infection,” Gewirtz said. “Rather, we hypothesize that the composition of the gut microbiota broadly influences susceptibility to respiratory viral infection. Microbe-mediated programming of constitutively resident alveolar macrophages may not only influence the severity of acute respiratory viral infection, but may also be a long-term determinant of respiratory viral infection.”

This story has been published from a news agency feed without text modifications. Only the title has changed.

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