The human immune system’s first line of defense is a type of immune cell called a neutrophil. Neutrophils constantly circulate in the bloodstream, but leave the circulation to travel to sites of infection when disease-causing pathogens (e.g., bacteria, fungi and viruses) enter the body. Neutrophils kill pathogens by producing reactive oxygen species—a byproduct of metabolism—and shooting out networks of fibers to immobilize and kill pathogens, called neutrophil extracellular traps. Previous studies have shown that exposure to environmental toxins, including cigarette smoke, can reduce neutrophils’ capacity to destroy pathogens. However, less is known about the effects of e-cigarette vapor on neutrophil function.
Researchers from the University of California San Diego and the VA San Diego Healthcare System examined neutrophils from healthy men and women that were treated with e-cigarette vapor extract and then exposed to bacteria. The treated cells had reduced mobility, which may translate to a lower ability to relocate from the bloodstream to the site of infection. These vapor-exposed cells also produced fewer neutrophil extracellular traps and were less able to destroy bacteria.
The research team also studied the effects of e-cigarette vapor on abdominal infection in mice. One group of mice was exposed to the vapor for one hour daily five days a week for a month prior to exposure to infection, while a control group breathed only room air throughout the trial. “Fewer neutrophils migrated out of circulating blood and into the infected peritoneal space in e-cigarette mice compared to air controls,” the researchers wrote. RNA analysis of lung tissue from the e-cigarette-exposed mice found decreased expression in genes that signal movement of immune cells out of blood circulation and toward infection sites. This likely means that e-cigarettes alter immune cell function throughout the body, leading to decreased migration of neutrophils to any sites of infection, the research team explained.
“Our findings provide further evidence that e-cigarette vapor alters host innate immune responses and may lead to increased susceptibility to infections and/or increased severity of infections in human e-cigarette users,” the researchers wrote.
Read the full article, “E-cigarette use increases susceptibility to bacterial infection by impairment of human neutrophil chemotaxis, phagocytosis and NET formation,” published ahead of print in the American Journal of Physiology—Cell Physiology.
Physiology is the study of how molecules, cells, tissues and organs function in health and disease. Established in 1887, the American Physiological Society (APS) was the first U.S. society in the biomedical sciences field. The Society represents nearly 10,000 members and publishes 15 peer-reviewed journals with a worldwide readership.
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