TGF-beta s and TGF-beta type II receptor in human epidermis: differential expression in acute and chronic skin wounds

Exogenously applied transforming growth factor-beta (TGF-beta) isoforms enhance wound healing processes in animal models; however, little is known about the expression of endogenous TGF-beta s and TGF-beta receptors in intact human skin or during wound healing. The present study has revealed several unexpected findings by means of in situ hybridization and immunohistology techniques. In humans, TGF-beta 3 is constitutively expressed in the epidermis of intact skin and in that of acute and chronic wounds--a pattern of expression closely mirrored by the TGF-beta type II receptor. Although not detected in intact skin, TGF-beta 1 mRNA expression was observed in the regenerating epidermis of acute (thermal) wounds but was not found in chronic decubital (pressure) wounds. TGF-beta 2 mRNA expression was not detected in the epidermis of any human skin or wound biopsies. From these findings we suggest that constitutive expression of TGF-beta 3 is important for maintenance of epidermal differentiation and that an induction of TGF-beta 1 expression is essential for re-epithelialization of human skin wounds. Lack of TGF-beta 1 expression in chronic pressure wounds may be associated with their protracted healing tendencies.