Gut Bacteria May Shield Against Severe Respiratory Infections

Select gut bacteria offer significant protection against secondary bacterial pneumonia following a viral respiratory infection, such as influenza A, according to a recent study from Georgia State University. The research, published in Science Immunology, highlights the crucial role of gut microbiota composition in determining an individual’s susceptibility to severe illness during and after viral pandemics.

The Link Between Gut Health and Lung Immunity

The study focused on segmented filamentous bacteria (SFB), which are commonly found in the intestines of mammals. Researchers discovered that the presence of SFB markedly protected mice from lethal infections caused by Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus following influenza A virus infection. This protection is particularly significant as secondary bacterial infections are a major contributor to morbidity and mortality during influenza pandemics. Georgia State University News

How SFB Enhances Immunity

The protective effect of SFB is mediated by alveolar macrophages, specialized immune cells in the lungs. These cells often become dysfunctional after a viral infection like influenza. Yet, the study revealed that SFB epigenetically reprograms these alveolar macrophages, making them resistant to the damaging effects of the influenza virus and enabling them to effectively defend against subsequent bacterial pathogens. Science Immunology

“The intestine is normally colonized by thousands of different bacterial species but yet, incredibly, adding one more completely changes the way that lung macrophages respond to pathogens,” says Vu Ngo, a research assistant professor in the Institute for Biomedical Sciences at Georgia State University. Georgia State University News

Implications for Future Treatments

Researchers are optimistic that understanding the mechanism by which SFB reprograms alveolar macrophages could lead to new therapeutic strategies for mitigating the severity of a wide range of respiratory infections. Andrew T. Gewirtz of the Institute for Biomedical Sciences adds, “We’re very hopeful that we’ll soon be able to harness the mechanism by which SFB reprograms alveolar macrophages, yielding novel pharmacologic approaches to mitigate the severity of a broad assortment of respiratory infections.” Georgia State University News

Gut Microbiota and Viral Infections: A Broader Perspective

The connection between gut microbiota and immune responses to viral infections, including influenza, has been increasingly recognized by scientists. Research indicates that the microbial community in the gut can significantly influence the body’s immune reaction to these infections. PMC – NIH

This study was funded by the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health.