Prenatal E‐Cigarette Use Disrupts Blood‐Brain Barrier (BBB) Integrity and Induces Pro‐Inflammatory Cytokines in Postnatal Brain

Abstract

PurposeElectronic cigarette (e‐Cig) is often considered as a safer alternative to smoking for pregnant women however, its potential toxic effect on neonatal health warrants further investigation. Toxic effects of prenatal tobacco smoking on postnatal health have been reported in several studies however, regarding thorough investigation of e‐Cig exposure during pregnancy is currently unavailable. Due to the staggering growth in e‐Cig usage among pregnant women (10%), it has become critical to explore the consequences of maternal e‐cig use on postnatal health outcomes. Hence, in this study, we have evaluated the consequences of prenatal e‐Cig use during pregnancy on postnatal blood‐brain barrier (BBB) integrity, proinflammatory cytokine levels and behavioral outcomes in offspring.MethodPregnant CD1 mice (E5) were exposed to e‐Cig vapor (2.4% nicotine) till postnatal day (PD) 7. Weight of the offspring was measured up to PD 90. Nicotine and cotinine concentration in plasma and brain were measured in PD 7 offspring by LC‐MS/MS. The expression level of structural elements of the BBB including, tight junction proteins (ZO‐1, claudin‐5, occludin), astrocyte (GFAP), pericyte (PDGFRβ) and basement membrane (Laminin α1, Laminin α4) were analyzed in offspring using western blot and immunohistochemistry at PD 7, PD 23, PD 45 and PD 90. The expression level of pro‐inflammatory cytokines (IL‐1α, IL‐1β, IL‐2, IL‐4, IL‐5, IL‐6, IL‐7, IL‐10, IL‐12, IL‐17α, KC, LIX, MIP‐2 and TNF‐α) in brain were measured at PD 7 and PD 90. To evaluate behavioral outcomes, open field test, novel object recognition test and morris water maze test were performed on adolescent and adult offspring.ResultsReduced body weight was observed in e‐Cig exposed offspring at all time points till PD 90 compared to control (P <0.05). Plasma concentration of nicotine and cotinine in PD 7 offspring was 3.215 ng/mL and 3.373 ng/mL respectively whereas in brain, these two concentrations were 43.72 ng/mL and 1.123 ng/mL respectively. Significantly reduced expression of brain tight junction proteins and GFAP were observed in male and female offspring at PD 7, PD 23, PD 45 and PD 90 (P <0.05). Moreover, higher level of brain IL‐1α, IL‐6, IL‐7, IL‐10, IL‐17α, KC and TNF‐α was found in prenatally e‐cig exposed offspring at PD 7. However, only IL‐6 and IL‐17α were observed at higher levels in brain for prenatally e‐cig exposed adult offspring at PD 90 (P <0.05). Additionally, disrupted motor, learning and memory function were observed in prenatally e‐Cig exposed adolescent and adult offspring.ConclusionOur findings suggest that prenatal e‐Cig exposure induces potential neurotoxic effects on neonates by disrupting postnatal blood‐brain barrier integrity and inducing proinflammatory brain cytokines which may result in alteration in neurological, cerebrovascular, and behavioral outcomes.