Lung Histopathological Examination
Immediately after collection of the BALF samples, lung tissues were fixed in 4% paraformaldehyde, and then embedded in paraffin before sagittally cutting into 5 μm sections. Subsequently, the sections were stained with hematoxylin/eosin (H&E) or periodic acid-Schiff (PAS) to analyze the inflammatory cells infiltration and global cell hyperplasia, respectively. Finally, a semi-quantitative method as described previously was used to evaluate the peribronchial inflammation and global cell hyperplasia (29, 30).