Time Course for Bleomycin Induced Pulmonary Fibrosis. (A). Experimental design 1: Mice were injected with bleomycin (BLM) (5 mg · kg-1) intratracheally (IT) at D0. For time course experiment, at D0 (D0 = untreated control), D3, D7, D10, D14, D21 and D28, mice were killed and lung samples were collected for further analysis. (B). The expression profile of inflammatory cytokines in the bleomycin mouse model. Bleomycin (5 mg · kg-1) was injected on D0. The lung tissues were collected at the indicated time points. The investigated inflammatory cytokines were tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β) and IL-6. (C). The expression profile of collagen was estimated by hydroxyproline (HYP) assay at the indicated time points. n = 4–7. Bars: median values (IL-1β, IL-6, TNF-α) or mean ± SD (HYP). *P ≤ 0.05.