Figure 2. EMAPII is an essential mediator of CS-induced emphysema in mice.

(A and B) EMAPII expression after CS exposure. (A) Production of EMAPII (pro and mature forms) in lung lysates in mice exposed to CS (4 weeks) compared with that in control mice exposed to ambient air (air control [AC]), assessed by Western blot (mean densitometry units [DUs] normalized to vinculin ± SEM; *P < 0.05 versus control; n = 5/group). (B) EMAPII localization in the lung parenchyma detected by coimmunofluorescence with EMAPII antiserum (green), CD11b antibody (red), and DAPI (blue). In controls, EMAPII expression is sparse, and EMAPII colocalized with macrophages (arrowheads) (left panel). After CS exposure (2 months), EMAPII expression is increased both cellularly and extracellularly, less prominently colocalized with macrophages (arrowheads, middle), and increasingly expressed in parenchyma cells (arrows; right). Scale bar: 100 μm. (C–F) Effect of neutralizing EMAPII (E-AB) or control antibody (IgG) administered by nebulization (50 μg/100 μl) during month 3 of CS exposure on CS-induced lung injury at 4 months. (C) Treatment protocol. (D) Apoptosis detected by caspase-3 activity in lung lysates (caspase units normalized by protein; mean + SEM; *P < 0.05, ANOVA). (E) Number of cells in BALF, and (F) lung static compliance (mean + SEM; *P < 0.01, ANOVA). (G) Representative H&E-stained lung sections (scale bar: 100 μm) showing simplification of lung alveolar structures in response to CS but preserved alveolar architecture when treated with neutralizing EMAPII. (H) Morphometric measurement of MLIs (mean + SEM; *P < 0.05, ANOVA; n = 5–12).