Vapor from berry-flavored e-cigarettes can weaken the lungs' natural defenses by paralyzing immune cells, making it harder for the body to fight off infections, a Canadian study has found.
Previous research has confirmed that all vaping, no matter the flavor, can be harmful, but the scientists who led this research said their study added to a mounting body of evidence that showed that added flavorings could make vaping more dangerous.
"We need to be careful about the types of flavors that we're including in these products," Assistant Professor Ajitha Thanabalasuriar, of McGill University, Montreal, said in a statement.
"They can have detrimental effects. I think that's really the take-home message, especially some of these vaping products that are marketed for kids.
"The way they're sold, the type of containers they are sold in -- it's very colorful, it's really attractive to children, and this can be a really bad thing for our future."
Thanabalasuriar led the research with Erika Penz from the University of Saskatchewan. The team tested the effects of berry-flavored vape smoke on mice. Over several days, they exposed mice to e-cigarette vapor. Then, they used a live imaging technique to observe lung immune cells in real time.
Specifically, they observed alveolar macrophages: immune cells that defend delicate sections of the lower lungs from infections by regularly patrolling the site. They check for invaders by sending out protrusions to probe and sample surrounding areas, and by moving around.
But the scientists saw that, in the lungs of the mice exposed to berry-flavored vapor, the behaviors of alveolar macrophages changed. The cells moved less and became less effective at clearing away inhaled bacteria called Pseudomonas aeruginosa.
When the scientists carried out the same investigations with unflavored vapor, this didn't happen.
The team concluded that specific chemicals in the berry vapes paralyzed these immune cells in the lungs, which are usually responsible for clearing out harmful particles, and this left the body more vulnerable to lung infections.
Thanabalasuriar said she was inspired to carry out this research by reports of teenagers developing lung injuries in 2019, linked to the use of e-cigarettes.
She clarified that more work was needed to understand which compounds in the berry-flavored vapes were responsible for disrupting the immune cells, and to confirm whether the effects were the same in humans as in mice.
This research was funded by the Canadian Institute of Health Research, the McGill Interdisciplinary Initiative in Infection and Immunity and the Canadian Research Chair research allowance.
The paper was published in scientific journal Proceedings of the National Academy of Sciences (PNAS) in September.
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Kulle, A., Li, Z., Kwak, A., Mancini, M., Young, D., Avizonis, D. Z., Groleau, M., Baglole, C. J., Behr, M. A., King, I. L., Divangahi, M., Langlais, D., Wang, J., Blagih, J., Penz, E., Dufour, A., Thanabalasuriar, A. (2024). Alveolar macrophage function is impaired following inhalation of berry e-cigarette vapor, PNAS 121 (40): e2406294121. https://doi.org/10.1073/pnas.2406294121