Cigarette smoke has been found to worsen influenza A infections by disrupting the natural balance of throat microbiota, suggesting a significant link between smoking and respiratory disease severity.
- Cigarette smoke exposure is associated with many different respiratory diseases.
- A new study shows that cigarette smoke alters the microbial community in the gut and the oropharynx.
- The study shows that the cigarette-smoke-induced changes to the microbiota resulted in increased severity of disease in mice infected with influenza A virus.
Impact of Cigarette Smoke on Influenza Severity
New research published today (November 20) in mSystems, a journal of the American Society for Microbiology, reveals that cigarette smoke can disrupt the balance of oropharyngeal microbiota, worsening the severity of influenza A virus infections.
It has long been established that cigarette smoke is harmful, contributing to various respiratory diseases, including chronic pulmonary conditions and a higher risk of influenza-related complications. More recently, scientists have discovered that cigarette smoke also alters the composition of the oropharyngeal microbiota—the community of microorganisms in the soft palate, throat, tonsils, and back of the tongue. However, the significance of this disruption in relation to disease severity has remained unclear until now.
Microbiota Disruption by Smoking
In a new study, researchers showed that gut and oropharyngeal microbiota are altered by chronic cigarette exposure in mice. The researchers tried to disentangle the effect of smoking and the disordered microbiota by exposing mice to cigarette smoke and then cohousing mice exposed to cigarette smoke and air-exposed mice (control) with germ-free mice. This allowed the transfer of the microbiota from donor mice to the germ-free mice. The original germ-free mice were colonized either with bacteria from a smoke-exposed or air-exposed mouse. The scientists then infected the recipient mice with influenza A virus and monitored the disease course.
The investigators found that the original germ-free mice who received bacteria from smoke-exposed mice had a more severe disease course, which was measured by increased weight loss. In addition, virus infection was found to be associated with substantial changes in the oropharyngeal microbiota composition, especially at day 4 and day 8 after infection. The study design allowed for disentangling the effect of the disordered microbiota from the immune-modulating effects of actual cigarette smoke exposure.
Research Findings and Implications
“It is not only the smoking per se that impacts respiratory disease, but our data indicate that the smoker’s microbiota may also impact respiratory disease and/or infection. In our case, it impacts viral infection,” said corresponding study author Markus Hilty, Ph.D., associate professor at the Institute for Infectious Diseases, University of Bern in Switzerland. “The cigarette-induced disordering of the microbiota is probably an important factor to consider during viral infection.”
Reference: “Cigarette smoke-induced disordered microbiota aggravates the severity of influenza A virus infection” by Tsering Wüthrich, Simone de Brot, Veronica Richina, Nadja Mostacci, Zora Baumann, Nathan G. F. Leborgne, Aurélie Godel, Marco P. Alves, Mohamed Bentires-Alj, Charaf Benarafa and Markus Hilty, 20 November 2024, mSystems.
DOI: 10.1128/msystems.00790-24
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