The effects of TGF-β1 and IFN-α2b on decorin, decorin isoforms and type I collagen in hypertrophic scar dermal fibroblasts

Hypertrophic scars (HTS) develop from an excessive synthesis of structural proteins like collagen and a decreased expression of proteoglycans such as decorin. Previous research has demonstrated that decorin expression is significantly down-regulated in HTS, deep dermal tissue, and thermally injured tissue, reducing its ability to regulate pro-fibrotic transforming growth factor-beta 1 (TGF-beta 1) and normal fibrillogenesis. However, treatment of HTS fibroblasts with interferon-alpha 2b (IFN-alpha 2b) has been shown to reduce excessive collagen synthesis and improve HTS by reducing serum TGF-beta 1 levels. The expression of decorin isoforms in HTS is currently unknown and the effects of TGF-beta 1 and IFN-alpha 2b on decorin, decorin isoform expression and type 1 collagen are of great interest to our group. Dermal fibroblasts were treated with TGF-beta 1 and/or IFN-alpha 2b, for 48 h. The expression and secretion of decorin, decorin isoforms and type 1 collagen were quantified with reverse transcription-quantitative polymerase chain reaction, immunofluorescence staining and enzyme-linked immunosorbent assays. The mRNA expression of decorin and each isoform was significantly reduced in HTS fibroblasts relative to normal skin. TGF-beta 1 decreased the mRNA expression of decorin and decorin isoforms, whereas IFN-alpha 2b showed the opposite effect. IFN-alpha 2b significantly inhibited TGF-beta 1's effect on the mRNA expression of type I collagen alpha 1 in papillary dermal fibroblasts and overall showed relative effects of inhibiting TGF-beta 1. These data support that a further investigation into the structural and functional roles of decorin isoforms in HTS pathogenesis is warranted and that IFN-alpha 2b is an important agent in reducing fibrotic outcomes.