Biomarkers of airway Immune homeostasis Differ Significantly with Generation of E-Cigarettes.

Introduction:
This article presents a study on the effects of different generations of e-cigarettes on respiratory immune homeostasis. The study compares nonsmokers/nonvapers, smokers, third-generation e-cigarette users, and fourth-generation e-cigarette users. The study aims to understand differences in biomarkers of respiratory immune homeostasis between groups.

Key Points:

* The study used a multifaceted approach, including variable-by-variable analyses and machine learning analyses, to examine induced sputum cell differentials and soluble mediator milieu between exposure groups.
* Fourth-generation e-cigarette users had significantly decreased protein concentrations of soluble mediators, including sICaM-1 and sVCaM-1, which could indicate airway immune dysfunction.
* The study found that concentrations of sICaM-1 and sVCaM-1 were significantly lower in fourth-generation e-cigarette users compared with other groups, indicating increased susceptibility to rhinovirus infection.
* The study also found decreased concentrations of CRP, IFN-g, MCP-1, MMP-2, and VEGF in fourth-generation e-cigarette users compared with third-generation e-cigarette users, indicating suppressed host defense.
* Fourth-generation e-cigarette users had a significantly higher percentage of bronchial epithelial cells in their induced sputum than nonsmokers/nonvapers, which could indicate airway injury.
* The study found that fourth-generation e-cigarette users clustered differently and had the highest degree of separation from other tobacco use groups, indicating a unique biological response to exposure.
* The study suggests that the differences between third- and fourth-generation e-cigarette users could be driven by the use of nicotine salts, higher nicotine concentration, lower aerosolization temperature, and dual use with marijuana.

Main Message:
The study provides novel insights into differences in airway biomarkers of immune homeostasis between exposure groups. The findings demonstrate significant differences in biomarkers of respiratory immune homeostasis in fourth-generation e-cigarette users compared with nonsmokers/nonvapers and with third-generation e-cigarette users, with an overall phenotype of suppression of immune biomarkers. The study highlights the importance of considering device type in studies of e-cigarette inhalation toxicity and the need for continued investigation of the mechanisms underlying the effects of popular e-cigarette devices.

hickman E, Payton a, Duffney P, et al. Biomarkers of airway Immune homeostasis Differ Significantly with Generation of E-Cigarettes. american journal of respiratory and critical care medicine. 2022;206(10):1248-1258. doi:10.1164/rccm.202202-0373OC