Studies of transforming growth factors beta 1-3 and their receptors I and II in fibroblast of keloids and hypertrophic scars

Keloids are benign skin tumours occurring during wound healing in genetically predisposed patients. They are characterized by an abnormal deposition of extracellular matrix components, particularly collagen. There is uncertain evidence that transforming growth factor-beta (TGF beta) is involved in keloid formation. Therefore we investigated the expression of TGF beta 1, 2 and 3 and their receptors in keloids, hypertrophic scars and normal skin. Dermal fibroblasts were obtained from punch biopsies of patients with keloids and hypertrophic scars and from normal skin of healthy individuals. Total RNA was isolated and the expression of TGF beta 1, 2 and 3 and of TGF beta receptors I and II (TGF beta RI and II) was analysed by real-time PCR using the Lightcycler technique. Our data demonstrate significantly lower TGF beta 2 mRNA expression in hypertrophic scar fibroblasts as compared with fibroblasts derived from kelloids and normal skin (p<0.05). In contrast, TGF beta 3 mRNA expression was significantly lower in keloid fibroblasts in comparison with fibroblasts derived from hypertrophic scar and normal skin (p<0.01). TGF beta RI mRNA expression was significantly decreased in hypertrophic scar fibroblasts (p < 0.01) and TGF beta RII mRNA expression was decreased in keloids compared with hypertrophic scar fibroblasts (p<0.001). The ratio of TGF beta RI/TGF beta RII expression was increased in keloids compared with hypertrophic scar and normal skin fibroblasts. As recently supposed, an increased TGF beta RI/TGF beta RII ratio could promote fibrosis. Therefore our data support a possible role of TGF beta RI and TGF beta RII in combination with a certain TGFfl expression pattern as fibrosis-inducing factors in keloids.