Significant correlation between endothelial nitric oxide synthase (eNOS) expression and alveolar repair in elastase-induced rat pulmonary emphysema

Abstract

Background and purpose: Angiogenic factors, such as endothelial nitric oxide synthase (eNOS), are thought to play an important role in the repair of pulmonary emphysema (PE); yet, the correlation of the factors involved has not been investigated. We conducted this study to clarify the positive correlation between eNOS expression and alveolar repair in PE recovery. Methods: We used elastase to induce PE in rats, which were divided into Groups A (Control), B (G-CSF), C (PE) and D (PE + G-CSF). G-CSF was injected for 12 days, 4 weeks after which the alveolar walls, arterioles, and angiogenic factors including eNOS were examined histopathologically and by western blotting. Results: In comparing Groups A, B, C, and D, the alveolar density was 2.4 ± 0.2, 2.4 ± 0.1, 1.8 ± 0.1, 2.5 ± 0.1 per 100 μm2, respectively (C vs. others; p < 0.00001) and the number of arterioles was 4.5 ± 1.0, 5.6 ± 0.6, 3.2 ± 0.5, 5.5 ± 0.7/mm 2, respectively (C vs. others; p < 0.05). Immunohistochemical staining (IHC) revealed different eNOS expression in Group D versus Group C (p < 0.0001) and western blotting revealed different eNOS, VEGF, and FLT-1 expression in Group D versus Group C (p < 0.01, p < 0.05, p < 0.001), reflecting the contribution of angiogenesis to PE repair. eNOS showed a significantly positive correlation to alveolar density and arteriole repair. Conclusion: Alveolar repair was correlated positively with eNOS expression by vascular regeneration in elastase-induced rat PE. © 2012 Springer.