“…Tissue sections were stained with hematoxylin and eosin (H&E) for histological evaluation. In addition, the following cellular markers were visualized: CD45 for hematopoietic cells (1:500, MCA2220GA, Biorad, Hercules, CA), PU.1 for differentiating monocytes (1:400, Santa Cruz Biotechnology, H0503), myeloperoxidase for neutrophils (MPO, 1:500, A-0398, Dako, Santa Clara, CA), tumor protein 63 for basal cells (P63, 1:8000, ab124762, Abcam), keratin 14 for differentiating basal cells (KRT-14, 1:1000, 905301, Biolegend, San Diego, CA), thyroid transcription factor-1 for Club and alveolar epithelial type (AEC) 2 cells (TTF-1, 1:8000, WRAB-1231, Seven Hills Bioreagents, Cincinnati, OH) and Ki67 for proliferation (1:1000, 15580, Abcam, Cambridge, UK) ( 7 , 12 , 16 , 21 ). Immunohistochemical protocols were performed as previously published, while the PU.1 protocol was modified for optimal signal emission.…”