Electronic or e-cigarettes impair innate immune defenses and promote the growth of bacteria in the airways, according to the results of a recent mouse study, “Electronic cigarette inhalation alters innate immunity and airway cytokines while increasing the virulence of colonizing bacteria,” published in the Journal of Molecular Medicine.
A research team at University of California, San Diego School of Medicine and Veterans Affairs San Diego Healthcare System reported that exposure of human epithelial cells to increasing doses of e-cigarette vapor is associated with dose-dependent cell death. Specifically, exposure of key cells of the defense system, including alveolar macrophages and neutrophils, as well as epithelial cells in airways, result in decreased antimicrobial activity against the bacterium Staphylococcus aureus.
A lead researcher said some changes in the mice are also found in the airways and blood of human cigarette smokers. Other oddities discovered in the e-smoking mice are also seen in people with cancer or other lung diseases.
The team showed that mice that inhaled e-cigarette vapor one hour a day for four weeks had altered secretion of immunomodulating cytokines, which are molecules that mediate and regulate immunity and inflammation, in the airways. E-cigarette vapor led to increased expression of inflammation markers, and after exposure, the Staphylococcus aureus colonizer become more virulent, showing increased biofilm formation, adherence, and invasion of epithelial cells and higher resistance to antimicrobial peptides.
“This study shows that e-cigarette vapor is not benign — at high doses it can directly kill lung cells, which is frightening,” the study’s lead author, Dr. Laura E. Crotty Alexander, a staff physician at the Veterans Affairs San Diego Healthcare System and assistant clinical professor at UC San Diego School of Medicine, said in a press release.
“We already knew that inhaling heated chemicals, including the e-liquid ingredients nicotine and propylene glycol, couldn’t possibly be good for you. This work confirms that inhalation of e-cigarette vapor daily leads to changes in the inflammatory milieu inside the airways,” she said.
“We don’t know specifically which lung and systemic diseases will be caused by the inflammatory changes induced by e-cigarette vapor inhalation, but based on clinical reports of acute toxicities and what we have found in the lab, we believe that they will cause disease in the end,” Alexander said. “Some of the changes we have found in mice are also found in the airways and blood of conventional cigarette smokers, while others are found in humans with cancer or inflammatory lung diseases.”
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