Spatial and temporal expression of types I and II receptors for transforming growth factor β in normal equine skin and dermal wounds

Objective-To describe immunolocalization of TGF-beta receptors (RI and RII) in normal equine skin and in thoracic or limb wounds, healing normally or with exuberant granulation tissue (EGT). Study Design-Group A: six wounds on one metacarpus and one midthoracic area. Group B: six wounds on both metacarpi, one of which was bandaged to stimulate EGT. Immunohistochemistry was used to detect RI and RII expression in wound margins. Animals-Eight horses, randomly assigned to one of two study groups. Methods-Neutralizing polyclonal anti-rabbit RI and RII antibodies were used to detect spatial expression of RI and RII in biopsies obtained before wounding, at 12 and 24 hours, and 5, 10 and 14 days after wounding. Results-RI and RII were co-localized in both unwounded and wounded skin. There were no differences in cell types staining positively between tissues obtained from the limb and the thorax, or from normally healing limb wounds and limb wounds with EGT, at any time. Because of increased cellularity within EGT, staining intensity of limb wounds with 'proud flesh' was greater than limb wounds healing normally, and thoracic wounds, during the proliferative phase of repair. Conclusions-Strong expression of RI and RII, particularly in limb wounds with EGT, suggested that signalling for stimulation of matrix proteins is in place to contribute to scarring. Clinical Relevance-This information may help determine the appropriate time for using receptor antagonists to prevent scarring of limb wounds of horses. (C) Copyright 2004 by The American College of Veterinary Surgeons.