E-cigarette vapor exposure in utero causes long-term pulmonary effects in offspring

Abstract

The in utero environment is sensitive to toxicant exposure, altering the health and growth of the fetus, and thus sensitive to contaminant exposure. Though recent clinical data suggest that e-cigarette use does no further harm to birth outcomes than a nicotine patch, this does not account for the effects of vaping during pregnancy on the long-term health of offspring. Pregnant mice were exposed to: 1) e-cigarette vapor with nicotine (PV + Nic; 2% Nic in 50:50 propylene glycol: vegetable glycerin), 2) e-cigarette vapor without nicotine [PV; (50:50 propylene glycol:vegetable glycerin)], or 3) HEPA filtered air (FA). Dams were removed from exposure upon giving birth. At 5 mo of age, pulmonary function tests on the offspring revealed female and male mice from the PV group had greater lung stiffness (Ers) and alveolar stiffness (H) compared with the FA group. Furthermore, baseline compliance (Crs) was reduced in female mice from the PV group and in male mice from the PV and PV + Nic groups. Lastly, female mice had decreased forced expiratory volume (FEV0.1) in the PV group, but not in the male groups, compared with the FA group. Lung histology revealed increased collagen deposition around the vessels/airways and in alveolar tissue in PV and PV + Nic groups. Furthermore, goblet hyperplasia was observed in PV male and PV/PV + Nic female mice. Our work shows that in utero exposure to e-cigarette vapor, regardless of nicotine presence, causes lung dysfunction and structural impairments that persist in the offspring to adulthood.

Keywords: e-cigarette; fibrosis; in utero; pulmonary; vaping.

Graphical abstract

Figure 1.

A–C: litter characterization from mice exposed to e-cigarette vapor in utero revealed no changes in pup weight (A), male:female ratio (B), or litter size (C). D: When pups grew to adulthood (5 mo), body weight was significantly increased in PV and PV + Nic groups compared with FA in female, but not male mice. E and F: adult mice exposed to e-cigarette vapor in utero had no changes in lung weight/body weight (E), but male mice had reduced liver weight (F) compared with FA control (*P < 0.05, **P < 0.01 via one way ANOVA. N = 10–12; error bars indicate means ± SE). FA, filtered air; PV, e-cigarette vapor; PV + Nic, e-cigarette vapor with nicotine.

Figure 2.

FOT measurements from pulmonary function demonstrated (A) in utero e-cigarette exposure increased stiffness (Ers) and decreased compliance (Crs) in PV and PV + Nic lungs compared with FA (filtered air). B: NPFE measured a FEV0.1 decrease in PV females and Quick-Prime measurements show an increase of alveolar tissue stiffness (H) in PV males and females compared with FA control (*P < 0.05, **<0.01, ***P < 0.001 via one way ANOVA. N = 8–12; error bars indicate means ± SE). FEV0.1, decreased forced expiratory volume; FOT, forced oscillation technique; PV, e-cigarette vapor; PV + Nic, e-cigarette vapor with nicotine.

Figure 3.

A: Masson’s Trichrome staining indicates increased levels of fibrotic tissue (blue) around the airways and blood vessels between FA, PV, and PV + Nic, for both females and males. (*P < 0.05, **P < 0.01 via one way ANOVA, N = 4–6); error bars show avg ± SE. In utero e-cigarette exposure also increases alveolar interstitial fibrosis. B: collagen III immunoblot of lung tissue indicates increased fibrosis in the male PV group compared to FA (*P < 0.05 via one way ANOVA, N = 4–6); error bars show avg ± SE. C: an increased amount of goblet cells is observed in PV and PV + Nic compared with FA. Goblet cells in the airway epithelium were quantified based on percent area using a five-point system: 0, no goblet cells; 1, <25% of the epithelium; 2, 25%–50% of the epithelium; 3, 50%–75% of the epithelium; and 4, >75% of the epithelium. (*P < 0.05 via Kruskal–Wallis Test, N = 4–5); error bars show avg ± SD. D: measurement of the distance-free space between alveoli (MLI). PV females and males are observed to have a larger MLI, or decreased amount of alveolar attachments, than the FA group (via one way ANOVA, N = 4–5); error bars show avg ± SE. PV, e-cigarette vapor; PV + Nic, e-cigarette vapor with nicotine.