New research published in mSystems, a journal of the American Society for Microbiology, has revealed that cigarette smoke disrupts the oropharyngeal microbiota and worsens the severity of influenza A virus infections. The findings underscore another serious consequence of smoking, linking it to increased vulnerability to viral respiratory diseases.
While the harmful effects of cigarette smoke on respiratory health are well-documented, this study sheds light on how it alters microbiota composition, potentially playing a key role in worsening infections. The oropharynx—comprising areas like the throat, tonsils, and back of the tongue—is significantly affected by chronic cigarette exposure, resulting in disordered microbiota.
Researchers conducted a controlled study using mice to explore these effects. They exposed some mice to cigarette smoke and others to clean air. Germ-free mice were then cohoused with smoke-exposed or air-exposed mice to transfer microbiota from the donors to the germ-free recipients. These germ-free mice were subsequently infected with influenza A virus to study the progression of the disease.
The findings were significant: germ-free mice colonized with microbiota from smoke-exposed mice experienced more severe influenza infections, marked by increased weight loss compared to those colonized with microbiota from air-exposed mice. The study also observed substantial changes in the oropharyngeal microbiota at days 4 and 8 after infection, suggesting that microbiota alterations play a critical role in disease progression.
The researchers emphasized that the disordered microbiota, independent of direct cigarette smoke exposure, can exacerbate viral infections. Markus Hilty, Ph.D., corresponding author and associate professor at the University of Bern, noted, “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.”
This study highlights the importance of considering microbiota health in understanding the risks associated with smoking. Beyond its direct effects, cigarette smoke-induced changes in microbiota composition may represent a key factor in heightened vulnerability to respiratory diseases, including viral infections like influenza A.