IL-17a knockout alleviates pulmonary injury and cancer stem cell properties in mice following PM2.5 exposure for 3 months. (A) H&E staining (up panel) and Masson trichrome staining (down panel) of lung sections from IL-17a+/+ and IL-17a-/- mice challenged with or without PM2.5 for 3 months (n = 6). Scale bar, 100 μm. (B) Protein levels in BALF were measured (n = 8). (C) The total number of cells in BALF was assessed (n = 8). (D) The number of neutrophils in BALF was measured (n = 8). (E) Serum TNF-α and IL-6 levels in mice were measured by ELISA (n = 8). (F) TNF-α and IL-6 mRNA levels in the pulmonary samples were determined using RT-qPCR analysis (n = 4). (G) Fibrosis-associated genes as shown were tested using RT-qPCR analysis (n = 4). (H) Genes associated with lung cancer progression were calculated using RT-qPCR analysis (n = 4). (I) IHC staining of c-Myc and SOX2 in pulmonary sections from the indicated groups of mice (n = 6). Scale bar, 100 μm. All data are expressed as mean ± SEM. *p<0.05 and **p<0.01 compared to the FA/IL-17a+/+ group; +p<0.05 compared to the PM2.5/IL-17a+/+ group.