Abstract Introduction Fourth-generation, high nicotine, flavored e-cigarettes are used widely among young adolescents with asthma, a lung disease characterized by airway inflammation and exacerbated by environmental stimulants. Combined with daily e-cigarette exposures, we used ovalbumin (OVA) to induce a Th2-high mouse model of asthma and assess the impact of e-cigarette aerosols (commonly called vapor) on immunity in the lung during allergic inflammatory airways disease (AIAD) pathogenesis. Methodology Adolescent (6-9 week old), male and female BALB/c mice underwent whole-body exposure (inExpose; SCIREQ) to freshly generated JUUL Virginia Tobacco vapor (containing 5% nicotinic salts), non-flavored e-cigarette vapor propylene glycol and glycerol (PG/Gly) with 5% nicotinic salts, non-flavored nicotine-free e-cigarette vapor (PG/Gly), or room air (controls) for 1hr/day, 5days/week, for 8 weeks. AIAD induction was done at 4 weeks (OVA+AlOH intraperitoneally 1 week apart; intranasal OVA qod). Tissue dissociation was performed on right lung lobes (Lung Dissociation kit; Miltenyi Biotec) and Flow cytometry conducted. RNA was isolated (RNeasy kit; QIAGEN) and sequenced (Total RNA Prep; Illumina) from the left lung. RSEM and Bowtie packages were used to align and quantify reads to mus musculus (GRCm39) reference cDNA index. DEseq2 (R version 4.5.1) was used to perform differential gene expression analysis. Bronchoalveolar lavage (BAL) was collected by flushing airways with cold PBS, and concentrations of IL-4, IL-5, and IL-13 were quantified by ELISA (RnD Systems). Results Exposure to flavored, nicotine-containing e-cigarettes before and during AIAD induction was associated with reduced recruitment of leukocytes, inflammatory monocytes, macrophages, dendritic cells, and CD4+ T cells (p 0.05) to the lung parenchyma; and downregulation of 217 significantly differentially expressed genes, including: itk (log2FC=-5.68, padj0.01), itgax (log2FC=-1.39, padj0.01), il17re (log2FC=-1.35, padj0.05), and csf2rb2 (log2FC=-1.24, padj0.05), which are involved in IL-4 production, dendritic cell priming, epithelial cytokine responses, and eosinophil recruitment and function, respectively. IL-4 was diminished in airways of mice exposed to flavored, nicotine-containing e-cigarettes relative to AIAD mice (p 0.05). Conclusion Some e-cigarette chemicals, like those within JUUL Virginia Tobacco, can suppress lung immune responses and inflammation in mice, especially by reducing Th2 pathway activity. While the impact on asthma severity is unclear, it could be harmful for processes needing a strong Th2 response such as tissue repair, highlighting the need for more research on the safety of e-cigarette flavorants. This abstract is funded by: NHLBI K24 HL155884, NHLBI R01 HL137052, VA Merit 1I01BX004767, and TRDRP T30IP0965
Gaboyan et al. (Fri,) studied this question.