Evaluation of the Effect of a Nasal Allergen Challenge With Dermatophagoides Farinae Extract on Nasal Airway Inflammation in Allergic Individuals, Comparing E-cigarette Users to Cigarette Smokers and Non-smokers.

The recent increase in popularity of e-cigarettes for smoking cessation or in combination with conventional cigarettes has led to safety concerns regarding their potential role in respiratory disease. These tobacco alternative devices were initially perceived as a "safer" alternative to cigarettes and were marketed without much known about their health effects. Increasing evidence demonstrates that while they contain fewer toxins and carcinogens than conventional cigarettes, they do involve delivery of ultrafine particles to the lower airways and can contain heavy metals and other chemicals. Tobacco smoke may augment allergic inflammation resulting from allergic rhinitis and/or asthma. Animal models of allergic asthma demonstrate aggravation of allergen-induced airway inflammation following inhalation of e-cig cartridge solution, with increased airway eosinophil infiltration, production of Th2 cytokines, and airway hyperresponsivness. In vitro studies in human tissues have demonstrated pro-inflammatory responses to e-cig vapour extract yet have not evaluated the effects of e-cig usage on allergic inflammation in human airways. Current evidence suggests that e-cigarette use augments allergic inflammatory responses in a similar way as tobacco smoke, yet a head-to-head comparison of the effects of these two exposures has not been performed in humans.

Use of tobacco products remains a pervasive problem in our society and around the world, with significant impact on respiratory health and quality of life. With the emergence of new non-tobacco based nicotine products like e-cigarettes, it is important to understand the impact these substances have on respiratory health and disease. The aim of this study is to study the impact of these products on allergic inflammation in house dust mite-allergic subjects who already routinely use e-cigarettes and to compare their responses to those of cigarette smokers and non-smokers. A thorough understanding of the potential health impacts of tobacco alternative substances is needed, especially given the rising popularity of such products with adolescents and young adults to whom these substances have particular appeal given their purported "safety" and variety of flavors to choose from.