E-cig exposure reduces pulmonary bacterial clearance in mice infected with <i>S</i>. <i>pneumoniae</i>.

<p>Mice were exposed to air or E-cig for 2 wks, then infected intranasally with 1x10⁵ colony forming units (CFU) of <i>S</i>. <i>pneumoniae</i>. Inflammation (A) and bacterial CFUs (B) were determined in BAL at 24h after infection (N = 10 mice per group). (C) In a separate group of mice, bacterial CFUs were quantified in lung homogenates (N = 10 mice per group). (D) Alveolar macrophages from air or E-cig exposed mice were harvested and infected with <i>S</i>. <i>pneumoniae</i> at multiplicities of infection of 10 and 20. Bacterial CFUs were quantified in cell-free culture media at 4 h after infection. (E) Intracellular (internalized) and extracellular bacteria (cell-free culture media) were quantified at 1 h after <i>ex vivo</i> infection of alveolar macrophages with an MOI of 20. (F) Alveolar macrophages were harvested at 2h after final exposure, stained with antibodies against CD36 and MARCO, and analyzed by flow cytometry. (G) Bacterial clearance was measured in alveolar macrophages from mice exposed to air or traditional E-cig vapor. *p<0.05 by Student’s two-tailed t-test.