Acute Vaping of a golden Syrian Hamster is Feasible and Leads to Nicotine-Dependent Respiratory Tract Inflammation

IntroductionE-cigarette vaping has become a major portion of nicotine consumption, especially for children and young adults. Although it is branded as a safer alternative to cigarette smoking, murine and rat models of sub-acute and chronic e-cigarette vaping exposure have shown many pro-inflammatory changes in the respiratory tract. An acute vaping exposure paradigm has not been demonstrated in the golden Syrian hamster, and the hamster is a readily available small animal model that has the unique benefit of becoming infected with and transmitting SARS-CoV-2 without genetic alteration to the animal or virus. MethodsUsing a two-day, whole-body vaping exposure protocol in male golden Syrian hamsters, we evaluated serum cotinine, bronchoalveolar lavage cells, lung and nasal histopathology, and gene expression in the nasopharynx and lung through RT-qPCR. Depending on the presence of nonnormality or outliers, statistical analysis was performed by ANOVA or Kruskal-Wallis tests. For tests that were statistically significant (p-value <0.05), post-hoc Tukey-Kramer and Dunns tests, respectively, were performed to make pairwise comparisons between groups. ResultsIn nasal tissue, RT-qPCR analysis revealed nicotine-dependent increases in genes associated with type 1 inflammation (CCL-5 and CXCL-10), fibrosis (TGF-{beta}), and a nicotine-independent decrease in the vasculogenesis/angiogenesis gene VEGF-A. In the lung, nicotine-dependent increases in the expression of genes involved in the renin-angiotensin pathway (ACE, ACE2), coagulation (tissue factor, Serpine-1), extracellular matrix remodeling (MMP-2, MMP-9), type 1 inflammation (IL-1{beta}, TNF-, and CXCL-10), fibrosis (TGF-{beta} and Serpine-1), oxidative stress response (SOD-2), neutrophil extracellular traps release (ELANE), and vasculogenesis and angiogenesis (VEGF-A) were identified. ConclusionTo our knowledge, this is the first demonstration that the Syrian hamster is a viable model of e-cig induced inhalational injury. In addition, this is the first report that e-cig vaping with nicotine can increase tissue factor gene expression in the lung. Our results show that even an acute exposure to e-cigarette vaping causes significant upregulation in the respiratory tract of pathways involving the renin-angiotensin system, coagulation, extracellular matrix remodeling, type 1 inflammation, fibrosis, oxidative stress response, NETosis, vasculogenesis, and angiogenesis.