October 15, 2019
2 min read

E-cigarette flavor may affect asthma pathophysiology

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Charles G. Irvin
Charles G. Irvin

The effect of electronic cigarettes without nicotine on allergic airway disease may depend on flavor, which suggests that some flavored e-cigarettes may alter the pathophysiology of asthma, a recent study on mice suggests.

The flavors cause changes in inflammation in the lung in normal lungs, but particularly in the allergic lungs,” Charles G. Irvin, PhD, FERS, professor of medicine and molecular physiology and biophysics at the University of Vermont, told Healio Pulmonology. “There are some effects, in at least one of the flavorings, on lung function that would be in the direction of making asthma worse.”

Researchers examined groups of eight to 12 mice challenged with house dust mite or phosphate buffered saline and exposed to room air or e-cigarette aerosol twice a day for 30 minutes each time, 6 days a week for 18 days. They were assessed 72 hours after final exposure. Flavors used for exposure included kola, black licorice, banana pudding or cinnacide, both with and without 12 mg/mL of nicotine.

According to Irvin, including nicotine as a variable was imperative to the study due to its suppressive effect on inflammation.

“If I have a kid, and the kid is only using flavors and another kid is using flavors and nicotine, those are two different situations,” he said.

The effect of nicotine-free e-cigarette exposure on airway inflammation was determined by measuring inflammatory cells in bronchoalveolar lavage fluid, whereas e-cigarettes’ effect on airway hyperresponsiveness was measured by examining changes in lung function during a methacholine challenge. E-cigarette exposure’s effect on airway remodeling was determined via a histological assessment of mucous hyperplasia from a periodic acid-Schiff-stained lung tissue and a measurement of soluble lung collagen content. Exposure’s effect on weight was also analyzed and was measured at day 21 of examination prior to lung function assessment.

Nicotine-free cinnacide exposure reduced airway inflammation (P = .045) and increased peripheral airway hyperresponsiveness (P = .02) compared with mice challenged with house dust mite and exposed to room air. Additionally, banana pudding flavor without nicotine increased soluble lung collagen (P = .049), and there was a trend toward increased airway inflammation with exposure to nicotine-free black licorice (P = .089). All e-cigarettes with nicotine were found to suppress airway inflammation (P = .001) but did not affect airway remodeling or hyperresponsiveness.

“The stuff is not just water vapor,” Irvin said. “The flavors have an effect on inflammation, and you can’t predict it. Every flavor is going to be different.” – by Eamon Dreisbach

Disclosures: The authors report no relevant financial disclosures.