Collagen synthesis is enhanced by TGF-β
in control and COPD fibroblasts and attenuated by iloprost treatment. Collagen I production was measured as the propeptide of type I procollagen (PINP) in the supernatant from distal lung fibroblasts from control subjects (n = 5; A) and patients with COPD (n = 7; B). Cells were stimulated with iloprost (1000 nM) and TGF-β1 (10 ng/ml) in 0.4% fibroblast medium pretreated with indomethacin (3 μM). Data are presented as median with individual values and median values are represented as a line. *p < 0.05. Statistical analysis is performed with Mann Whitney t-test to compare differences between control and COPD fibroblasts and Wilcoxon paired rank sum test is used to analyze differences within the control and COPD fibroblasts.