Figure 4.
Extracellular vesicles (EVs) from current smokers drive damage through neutrophil elastase (NE) and matrix metalloproteinase 12 (MMP12). Airway EVs from current smokers, former smokers, and never-smokers were harvested and purified from BAL fluid. EVs were delivered intratracheally to naive C57BL/6 mice at a dose of 107 EVs per mouse. Lungs were harvested for pathological analyses 1 week posttreatment. (A) Cumulative mean linear intercept (Lm) scoring was determined to quantify alveolar damage after treatment with nonpooled human EVs (n ⩾ 5 per group). (B) In subsequent experiments, current-smoker and never-smoker EVs were pooled and delivered to naive C57BL/6 mice at a dose of 107 EVs per mouse. In some conditions, EVs were pretreated with MMP408, NE Inhibitor II (NE Inh II), or both. Cumulative Lm scoring was determined to quantify alveolar damage (n = 5 per group). (C) Representative images (hematoxylin and eosin) 1 week after EV transfer. Scale bars, 100 μm. The quantified results are expressed in terms of mean ± SEM. For all comparisons, statistical significance was determined by Mann-Whitney test. *P < 0.05, **P < 0.01, and ****P < 0.0001. ns = not significant.