Vaping with or without nicotine freezes frontline immune cells

A new study has found that even moderate exposure to nicotine-free vapor from e-cigarettes can literally stop neutrophils, the body's frontline immune cells, in their tracks, reducing their ability to fight off foreign invaders. The researchers say their findings add to the evidence challenging the perception that vaping is safe and caution against long-term e-cigarette use.

Since their introduction in around 2007, electronic or e-cigarettes, otherwise known as vapes, have become very popular. One study estimates the global number of vapers in 2021 was 82 million, up from 68 million in 2020. Considered by some to be less harmful than cigarettes, and in some countries used as a smoking cessation tool, the rise in vaping has spawned research dedicated to determining just how safe they are.

Adding to the existing evidence, a new study by researchers at the University of Birmingham, UK, has found that vaping can prevent neutrophils, the immune system’s first line of defense against harmful foreign invaders, from doing their job effectively.

“E-cigarettes are a proven, lower-harm tool to help smokers quit smoking, but our data adds to current evidence that e-cigarettes are not harmless and highlights the need to fund longer-term studies in vapers,” said Aaron Scott, corresponding author of the study.

The researchers took blood samples from people who’d never smoked or vaped and exposed neutrophils taken from the blood to 40 puffs of unflavored vape (determined by previous studies to a low daily exposure). Half of the samples were exposed to nicotine-containing vapor from e-liquid, the other half to vapor that didn’t contain nicotine.

In both groups, with nicotine and without, the researchers found that the neutrophils remained alive but were stuck in place, incapable of executing their normal functions.

“We found that after short, low-level exposure to e-cigarette vapor, the cells remain alive but can no longer move as effectively and are unable to carry out their normal protective functions,” said Scott. “Interestingly, vapor from e-liquids which did not contain nicotine also had the same negative effects as vapor from e-liquids which did contain nicotine.”

Normally, small actin filaments in neutrophils help them maintain or change shape and allow them to move – or migrate – towards and surround invaders. In the neutrophils exposed to e-cigarette vapor, regardless of the presence of nicotine, the researchers observed high concentrations of the filament F-actin. When excessive, F-actin has previously been shown to impair neutrophil migration and their ability to ingest and destroy foreign bodies.

“In health, neutrophils normally protect the lungs by moving from the blood to the site of possible harm before using a number of protective functions to protect the lung,” said David Thickett, one of the study’s co-authors. “The observed impact that e-cigarette vapor had on their mobility is therefore of significant concern, and if this were to happen in the body, would make those who regularly use e-cigarettes at greater risk of respiratory diseases.”

Given the link between neutrophils and disease states, the researchers say their findings raise obvious concerns.

“Smoking has a well-documented impact on neutrophils, and this study further shows the impact that e-cigarettes still have on the immune system,” said Liz Sapey, another co-author. “Neutrophils are heavily implicated in aging and chronic obstructive [pulmonary] disease and their relationship with tissue damage, and the impact of vaping in suppressing neutrophil activity regardless of nicotine could have long-term implications for health.”

The study was published in the Journal of Allergy and Clinical Immunology.

Source: University of Birmingham