Effect of healing on the expression of transforming growth factor beta s and their receptors in chronic venous leg ulcers

The transforming growth factor betas are of major importance in the wound r epair process; however, no studies to date have investigated the role of th e transforming growth factor beta receptors in chronic venous leg ulcers or what effect healing has on these proteins. To determine whether the transf orming growth factor beta peptides and their receptors are expressed in chr onic venous wounds, we used immunofluorescent analysis and quantitative com petitive reverse transcription polymerase chain reaction to identify the pr otein and mRNA expression, respectively. Biopsy samples from wounds and nor mal skin were collected from 12 patients with chronic venous leg ulcers and three patients undergoing reconstructive surgery, respectively. Additional ly four of the chronic venous leg ulcer patients were re-biopsied between 2 and 8 wk after the first biopsy when the wounds had entered the healing ph ase. The tissue excised from the ulcers included the surrounding intact ski n, the ulcer edge, and the ulcer base. Immunofluorescent staining for trans forming growth factors beta1, beta2, and beta3 was observed within the epid ermis of the skin surrounding the chronic venous ulcers and in fibroblasts and inflammatory cells of the dermis, although this staining was not as str ong as that seen in normal unwounded skin. Very little staining could be se en within the ulcers for any of the ligands, however. In contrast the trans forming growth factor beta type I receptor was observed throughout the ulce rs and the normal unwounded skin biopsies, particularly in the basal epider mal cells. No immunofluorescence for the type II transforming growth factor beta receptor was observed in any of the ulcer biopsies investigated, alth ough it was observed throughout the epidermis and in fibroblasts and inflam matory cells in the surrounding skin. Quantitative, competitive reverse tra nscription polymerase chain reaction was used to analyze mRNA expression fo r transforming growth factor beta1 and the type II receptor in the nonheali ng ulcers and normal unwounded skin biopsies. These studies revealed that t ransforming growth factor beta1 and transforming growth factor beta recepto r II mRNA was expressed in all the chronic nonhealing ulcers albeit at very low levels for the type II receptor. In marked contrast to the staining ob served in nonhealing chronic ulcers, positive immunostaining was observed f or the transforming growth factor betas and both the type I and type II rec eptors in healing ulcers. These results suggest that the absence of a viabl e receptor complex for the transforming growth factor betas in nonhealing c hronic venous ulcers may contribute to wound chronicity.