SAECs inhibit TGF-β induced pro-fibrotic protein expression in human lung fibroblasts.

(A) A schematic of co-culture system of HLFs and SAECs. HLFs and SAECs were grown separately on lower wells and upper inserts, respectively, of a Transwell co-culture system. HLFs were washed with PBS, co-cultured with SAECs with or without TGF-β for 72 hours (unless otherwise indicated). (B) HLFs were treated with 5ng/ml TGF- β in the presence or absence SAECs and α-SMA protein expression was analyzed by western blot and densitometric analysis. (C) Soluble collagen in culture medium from co-cultures was measured by slot blot with densitometric analysis. (D, E) HLFs were co-cultured with SAECs from two additional (different donors). Blots are representative of at least three independent experiments. (F) Alveolar epithelial cells were co-cultured with HLFs, and HLF expression of α-SMA was determined by western blot. Note that in Fig 1F, the indicated samples were resolved on the same gel, and intervening irrelevant lanes are not shown. Densitometry of n = 3 replicates per cell strain, normalized to untreated control. Data shown are mean ± SD. *** = p<0.001 ** = p<0.01 and * = p<0.05 by ANOVA.