L17.    Proopiomelanocortin (POMC)-derived peptides and corticotrophin-releasing hormone (CRH) influence the behaviour of human scalp follicular and dermal fibroblasts by modulating cell proliferation and Transforming Growth Factor-beta (TGFβ)-associated collagen.
Shahidul Huq, David Sharpe, Richard Karoo, Susan Stevenson, Shola Adekunle, Kamil Asaad, Desmond Tobin*; Plastic Surgery and Burns Research Unit & *Medical Bioscience Research Group, School of Life Sciences, University of Bradford, Bradford, UK.

The skin both produces and is targeted by POMC and CRH peptides. Recently Boehm et al reported that alpha-melanocyte stimulating hormone (a-MSH) can antagonise TFGb-induced collagen production in dermal fibroblasts. Moreover, Jahoda et al have suggested that follicular fibroblasts may be a more effective wound healing cell. The purpose of the study was to characterise the expression of POMC and CRH peptides in fibroblast subpopulations and to investigate their effects on cell proliferation and collagen secretion. Fully matched sets of inter-follicular (DF), and follicular fibroblasts (dermal sheath-DS and follicular dermal papilla-DP) were obtained from the scalp of 5 normal healthy females (49-60y, passage 4-6) and cultured using conventional methodologies. The expression of POMC and CRH peptides, associated receptors (MC1-R, MOR and CRH-R1) and pro-hormone convertases (PC1 and PC2/7B2) were investigated using specific antibodies on serum-starved cells. Staining incidence and intensity were assessed by image analysis software (PaintShopPro). Cells were incubated with POMC and CRH peptides (10-8M) for 5d followed by assessment of proliferation (MTT assay) and TGFb-induced collagen secretion (Sircol assay). These studies were compared with fibroblast subpopulations in a “wounded”-state (Scratch assay). Inter-follicular and follicular fibroblast sub-populations variably expressed all POMC and CRH peptides, as well as PC1, PC2/7B2 and POMC and CRH peptide receptors. a-MSH, ACTH, CRH (but not beta-endorphin) stimulated the proliferation of all fibroblast subpopulations, compared to unstimulated controls. TGFb stimulated collagen secretion by all fibroblast types and this effect was antagonised by a-MSH, ACTH and CRH. Wounding of the fibroblast monolayers revealed increased basal collagen secretion in DS and less so in DF, but not in DP fibroblasts. This study demonstrated that all human scalp fibroblast sub-populations expressed the full POMC and CRH machinery in vitro. Furthermore, these peptides can antagonise TGFb-induced collagen secretion suggesting a possible role in cutaneous wound healing.