Figure 1.

Protease protein levels are equally increased in vapers’ and smokers’ BAL. (A) Representative Western blots showing increased protease protein in smokers’ and vapers’ BAL, along with albumin as loading control. Full blots are provided in Figure E1. (B–D) Densitometric analysis of total protease levels normalized to albumin for neutrophil elastase (B), MMP-2 (matrix metalloprotease-2) (C), and MMP-9 (D). (E) Representative Western blots of BAL protease inhibitors. (F–I) Densitometric analysis of BAL normalized to albumin control for A1AT (alpha-1 antitrypsin) (F), SLPI (G), TIMP1 (tissue inhibitor of metalloproteinases-1) (H), and TIMP2 (I). Values are log₂ fold change in smokers and vapers compared with age-matched nonsmokers; *P ≤ 0.05 and **P ≤ 0.001. Pink, female subjects; blue, male subjects. Data are shown as mean ± SD. All n = 14 subjects per group. Data were analyzed using ANOVA followed by Tukey’s test. SLPI = secretory leukocyte protease inhibitor.