Figure 3.

Platelet-derived TGFβ1 does not play a significant role in bleomycin-induced fibrosis. A: quantification of secreted active TGFβ1 by MLEC bioassay in unstimulated (white bars) or thrombin-treated (gray bars) PRP from littermate (n = 4) or TGFβ1^fl/fl.PF4-Cre (n = 5) mice. B: TGFβ1^fl/fl.PF4-Cre or littermate mice were given 50 IU bleomycin (n = 5/group) or saline (n = 3/group) via an oropharyngeal route. Fold-change in body weight loss was monitored for 21 days post instillation. C: representative micro-CT scans of lungs after 21 days of treatment (white asterisks denote fibrotic lesions). Percentage (D) or volume (E) of fibrotic lung tissue in micro-CT scanned lungs was determined using InForm analysis software (n = 3 saline/mouse group and n = 5 bleomycin/mouse group). F: total lung collagen of murine lungs was determined by reverse-phase HPLC (n = 3 saline/mouse group and n = 5 bleomycin/mouse group). Any statistical differences were determined using two-way ANOVA with Holm–Sidak post hoc testing or Mann–Whitney U tests. In B, asterisks represent significant differences between treatments in littermate control mice and apostrophes represent significant differences between treatments in TGFβ1^fl/fl.PF4-Cre mice. In D and E, asterisks above the bars represent significance between saline and bleomycin treatment. Any other significant differences are indicated (n/s = not significant, *P < 0.05, **P < 0.01, ***P < 0.001). MLEC, Mink lung epithelial cell bioassay; PRP, platelet-rich plasma.