title: The role of the activin system in keloid pathogenesis.
abstract: Keloid scars represent a pathological response to cutaneous injury under the regulation of many growth factors. Activin-A, a dimeric protein and a member of the transforming growth factor-beta superfamily, has been shown to regulate various aspects of cell growth and differentiation in the repair of the skin mesenchyme and the epidermis. Thus our aim was to study the role of activin and its antagonist, follistatin, in keloid pathogenesis. Increased mRNA expression for activin was observed in keloid scar tissue by performing RNase protection assay. Immunohistochemistry showed increased localization of both activin-A and follistatin in the basal layer of epidermis of keloid tissue compared with normal tissue. ELISA demonstrated a 29-fold increase in concentration of activin-A and an approximately 5-fold increase in follistatin in conditioned media in keloid fibroblasts compared with normal fibroblasts. Although keloid keratinocytes produced 25% more follistatin than normal keratinocytes, the amounts of activin-A, in contrast, was approximately 77% lower. Proliferation of fibroblasts was stimulated when treated with exogenous activin-A (46% increase in keloids fibroblasts) or following co-culture with hbetaAHaCaT cells (66% increase). Activin-A upregulated key extracellular matrix components, namely collagen, fibronectin, and alpha-smooth muscle actin, in normal and keloid fibroblasts. Co-treatment of follistatin with activin-A blocked the stimulatory effects of activin on extracellular matrix components. These findings emphasize the importance of the activin system in keloid biology and pathogenesis and suggest a possible therapeutic potential of follistatin in the prevention and treatment of keloids.
authors.affiliation: Department of Pharmacy, National University of Singapore, Singapore.
authors.forename: Anandaroop
authors.initials: A
authors.lastname: Mukhopadhyay
authors.forename: Sui Yung
authors.initials: SY
authors.lastname: Chan
authors.forename: Ivor J
authors.initials: IJ
authors.lastname: Lim
authors.forename: David J
authors.initials: DJ
authors.lastname: Phillips
authors.forename: Thang T
authors.initials: TT
authors.lastname: Phan
mesh_terms: D028341:Activins / Q000096:biosynthesis / Q000494:pharmacology / Q000502:physiology*; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D018920:Coculture Techniques; D017077:Culture Media, Conditioned; D019281:Dimerization; D004797:Enzyme-Linked Immunosorbent Assay; D004817:Epidermis / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000096:biosynthesis; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D038681:Follistatin / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D007627:Keloid / Q000378:metabolism / Q000473:pathology*; D015603:Keratinocytes / Q000378:metabolism / Q000473:pathology*; D012333:RNA, Messenger / Q000096:biosynthesis; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology
chemical_list: D017077:Culture Media, Conditioned; D016326:Extracellular Matrix Proteins; D038681:Follistatin; D012333:RNA, Messenger; D053773:Transforming Growth Factor beta1; C422405:activin A; D028341:Activins