Cardiac p16 Expression Following Vape Exposure with Nicotine Shows Sex-Specific Induction in Males but not Females

Vaping is marketed as a safe alternative to traditional cigarette smoking, but multiple studies demonstrate deleterious cardiopulmonary effects including cardiac function decline and fibrotic remodeling with alveolar size enlargement. Nicotine, a common constituent of vaping aerosol, stimulates p16 expression in pulmonary tissue but the impact on cardiac tissue remains unclear. In this study, mice were exposed to e-cigarette vape aerosol either containing nicotine (Vape Nicotine; VN) or without nicotine (Vape 0; V0). Non-exposed (No Vape; NoV) mice were used as controls. Cardiac effects were assessed by echocardiography, histology, and immunofluorescence to determine changes in function, morphology, p16, and Discoidin Domain Receptor 2 (DDR2). VN depressed cardiac function and increased collagen deposition relative to V0 and NoV. Interestingly, p16 expression was increased in cardiomyocytes and interstitial cells of male mice while remaining unchanged in females. In contrast to VN, V0 had no significant impact on cardiac function or p16 expression in males. Furthermore, collagen deposition in the V0 group was significantly lower than the VN group. Subsequent cardiac fibroblast analysis using DDR2 revealed increased expression within the V0 group relative to VN and NoV. Collectively, these findings show collagen accumulation as well as p16 expression prompted by vaping is mediated by nicotine as a constituent of vape juice. In contrast, vape aerosol alone promotes accrual of cardiac fibroblasts without concomitant changes in collagen accumulation or p16 expression. These results are the first to identify p16 induction with pathologic collagen deposition by exposure to vape aerosol containing nicotine in male cardiac tissue. The underlying basis for sex-specific differences in cardiac responses to vape aerosol exposure warrant further investigation, particularly those involving cellular and molecular changes that may lead to pathologic changes later in life.