A new study, titled “Exposure to Electronic Cigarettes Impairs Pulmonary Anti-Bacterial and Anti-Viral Defenses in a Mouse Model,” led by Thomas Sussan, PhD, an assistant scientist in the Department of Environmental Health Sciences at the Johns Hopkins Bloomberg School of Public Health, suggests that exposure to electronic cigarettes may weaken pulmonary immune response, and leave the lungs highly susceptible to the harmful byproducts of vaporized fluid and nicotine. The findings are available in the journal PLOS ONE.
While the dawn of e-cigarettes seemed to be, at first, an “easy way out” when it came to nixing harmful cigarette smoking, it quickly became a public health concern as it has grown in popularity among former smokers, and those who have never smoked before. In fact, a significant number of patients diagnosed with COPD — which many likely developed from years of cigarette smoking — have such a difficult time quitting smoking that they turn to e-cigarettes, which studies have shown might not be the “lesser evil” many believe them to be.
“Our findings suggest that e-cigarettes are not neutral in terms of the effects on the lungs,” notes senior author Shyam Biswal, PhD, a professor in the Department of Environmental Health Sciences at the Bloomberg School. “We have observed that they increase the susceptibility to respiratory infections in the mouse models. This warrants further study in susceptible individuals, such as COPD patients who have switched from cigarettes to e-cigarettes or to new users of e-cigarettes who may have never used cigarettes.”
The Bloomberg School investigators formed 2 mice cohorts: one was exposed to e-cigarette vapor in quantities approximately equally to the average human’s exposure for 2 weeks, while the other was exposed to plain air. They then subdivided each group into 3: one was given nasal drops with Streptococcus pneumoniae, the other influenza A, while the third did not receive any pathogen.
The scientists found that the mice exposed to e-cigarettes were more susceptible to both administered pathogens, with some of them even dying shortly after the bacteria or virus was introduced.
“E-cigarette vapor alone produced mild effects on the lungs, including inflammation and protein damage,” says Thomas Sussan, PhD, lead author and an assistant scientist in the Department of Environmental Health Sciences at the Bloomberg School. “However, when this exposure was followed by a bacterial or viral infection, the harmful effects of e-cigarette exposure became even more pronounced. The e-cigarette exposure inhibited the ability of mice to clear the bacteria from their lungs, and the viral infection led to increased weight loss and death indicative of an impaired immune response.”
The researchers also found e-cigarette vapor to contain free radicals — harmful compounds normally present in cigarette smoke and air pollution that damages cellular components and causes cell death. Cigarette smoke is known to contain about 1,014 free radicals per puff, and while e-cigarette vapor seems to have a far less amount, users tend to inhale much more vapor at one time and in a day.
“We were surprised by how high that number was, considering that e-cigarettes do not produce combustion products,” Sussan says. “Granted, it’s 100 times lower than cigarette smoke, but it’s still a high number of free radicals that can potentially damage cells.”
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