Figure 2.

1,25(OH)₂D₃ decreases TGF-β1-induced collagen production in nasal polyp-derived fibroblasts. Nasal polyp-derived fibroblasts were treated with TGF-β1 and/or 1,25(OH)₂D₃ or 1,25(OH)₂D₃ alone for 72 hours. (A,B) Expression levels of fibronectin mRNA and protein were determined by semi-quantitative RT-PCR analysis and Western blot analysis. Expression levels of housekeeping GAPDH mRNA and protein were utilized as internal controls. A representative experiment and quantitative determination of fibronectin mRNA and protein levels are shown. (C) Representative fluorescein immunocytochemistry for fibronectin (green) with nuclear DAPI (blue). Scale bar = 50 μm. (D) The amount of total soluble collagen in culture media was quantified by the Sircol collagen assay. All data are presented as mean ± SEM. Four primary cell lines from different donors were used. All experiments were performed in at least triplicate and repeated at least three times. *p < 0.05 vs. control, ^†p < 0.05, ^††p < 0.01 vs. TGF-β1.