Mast cells of the lungs during experimental exposure to glycerin-propylene glycol smoking mixture

Along with traditional nicotine-containing smoking mixtures ( tobacco products or cigarettes), some alternative smoking methods have recently become popular. The latter are based on heating a special liquid, vape, containing glycerin and propylene glycol. The effect of smoking vaping mixtures on the lungs, to date, remains unexplored. Mast cells seem to be involved in pathogenesis of these processes, being an essential cellular component of respiratory tract environment. The aim of this work was to study the effect of glycerin-propylene glycol smoking mixture on rat lung mast cells. The experiment was conducted in Wistar rats. The animals were placed in an inhalation chamber, where the rats were exposed daily for 1 hour for 3 months to: nicotine–containing smoking mixture (control), smoking mixture for vaping (experimental group); comparison group – intact rats. Histological methods were used to assess general pathology of the lung tissue, with mast cells being detected by means of toluidine blue staining followed by their typing. The degranulation coefficient and the average histochemical coefficient were calculated. Statistical processing was performed using the Mann–Whitney criterion (*, at p < 0.05 – the differences are significant). The experimental series showed that, after 3 months of exposure, pathological changes are observed in the lungs: fibrosis of the bronchial walls, lymphocytic-leukocytic infiltrations, bull formation, and a vascular sludge phenomenon. Exposure to both nicotine-containing and glycerin-propylene glycol smoking mixtures caused unidirectional changes in the respiratory tract, which are expressed as development of inflammatory processes and tissue remodeling. When exposed to smoking mixtures, mast cells in the lungs are irregularly shaped, elongated or fusiform. The mast cell population in the lungs responds to the exposure by increasing functional activity, regardless of the composition of the smoking mixture. Prolonged exposure to a glycerin-propylene glycol smoking mixture leads to an increase in the total number of mast cells, which is regarded as a long-term response from the microenvironment, suggesting a more significant negative effect of this smoking mixture.