Abstract Body (Do not enter title and authors here): Background: Smoking and family history are major risk factors for abdominal aortic aneurysm (AAA). Smoking is a powerful modulator of DNA methylation, and nicotine can cause heritable epigenetic alterations in animals and humans. We found that nicotine infusion and e-cigarette (e-cig) vaping augment murine AAA, and that parental nicotine infusion augments model AAA in offspring, altering tissue DNA methylation patterns.
Hypothesis: We investigated the effects of maternal e-cig vaping in mice on their offspring’s experimental AAA risk, and transgenerational DNA methylation and accessibility.
Methods: Two treatment arms were employed: 1) pre-fertilization or 2) peri-natal. Female ApoE-/- or C57BL6 mice (F0) were exposed to e-cig nicotine (24 mg/ml, 9 sec/min, 1 hour/day) or room air. Arm 1: treated 28 days, then mated to untreated controls. Arm 2: mated after 1 week of e-cig, then treated until end of gestation. At 10-12 weeks-old, aortic tissue and blood were obtained for RRBS-Seq and ATAC-seq analysis to evaluate DNA methylation and accessibility changes in parents and offspring. Parallel offspring underwent angiotensin-II infusion (1μg/kg/min; ApoE-/-) or local elastase infusion (5 min 2U/ml@120 mmHg; C57) to induce AAA. Aneurysm growth was ultrasound-tracked over 28 days.
Results: Maternal vape exposure altered aortic DNA methylation in offspring, with numerous differentially methylated and accessible regions (DMRs/DARs; q<0.1). Hundreds of DMRs were located in the same genes previously identified in offspring of nicotine-infused mice (see Background). Vaping altered offspring aortic methylation and accessibility patterns in AAA-related genes. DMR/DAR pathway analyses were enriched in transcription factors and inflammation/immune-related genes. Further, many DMR/DARs were located in genes harboring risk loci for human AAA from our recent collaborative publication. Maternal e-cig exposure augmented AAA size in both models, arms, and genders (p<0.05). AAA incidence and mortality were increased in ApoE-/- in both genders and arms. Effects were most significant in males.
Conclusions: E-cig nicotine exposure augments experimental AAA growth in multiple models across generations. These effects are accompanied by broad epigenetic changes in aorta and blood, including in key AAA modulator genes and immune pathways, with enrichment in transcription factors that target known AAA-related genes.