Fig. 2

The expression of HSP20 in AECs of mice in vivo. The inducible expression of HSP20 by oxidative stress in mouse AECs in vivo was tentatively explored in a preliminary experiment, where mice (n = 3) were exposed to filtered air, 0.5 and 2.0 ppm ozone, for 1 h (h) and their lungs were harvested 24 h after the exposure. a The IHC staining of HSP20 on lung tissue sections from preliminary experiment (black bar represents 50 μm). Then the expressions of HSP20 in AECs and lungs of an animal model that preconditioned with repeated low-level ozone exposures (0.5 ppm) were evaluated at protein and mRNA level. b HSP20 mRNA expression in lung tissues measured with RT-qPCR. c The expression of total and phosphorylated HSP20 protein in lung tissues measured with Western blot. The ratio of total HSP20 protein with actin (bottom left panel) and the phosphorylated- with the total- HSP20 protein (bottom right panel) were calculated based on their densitometry data, respectively. d The local expression of HSP20 on lung tissues were detected by IHC, and the typical pictures were presented (left panel) (the black bar represents 50 μm). The number of HSP20 positive cells per micrometer basal lamina (upper right panel) and the percentage of HSP20 positive cells (lower right panel) were counted and calculated on the segments of distant bronchi in HSP20-IHC stained lung sections. Data are presented as mean ± SD for n = 5 in each group. Prec. preconditioning, FA filtered air. Green wide arrow indicating HSP20-positive cells, red thin arrow indicating epithelial cell shedding, black short arrow indicating inflammatory cells