Proteolytic and non-proteolytic activation of keratinocyte-derived latent TGF-β1 induces fibroblast differentiation in a wound-healing model using rat skin.
Transforming growth factor-β1 (TGF-β1) reportedly causes the differentiation of fibroblasts to myofibroblasts during wound healing. We investigated the mechanism underlying the activation of latent TGF-β1 released by keratinocytes in efforts to identify promising pharmacological approaches for the prevention of hypertrophic scar formation. A three-dimensional collagen gel matrix culture was prepared using rat keratinocytes and dermal fibroblasts. Stratified keratinocytes promoted the TGF receptor-dependent increase in α-smooth muscle actin (α-SMA) immunostaining and mRNA levels in fibroblasts. Latent TGF-β1 was found to be localized suprabasally and secreted. α-SMA expression was inhibited by an anti-αv-integrin antibody and a matrix metalloproteinase (MMP) inhibitor, GM6001. In a two-dimensional fibroblast culture, α-SMA expression depended on the production of endogenous TGF-β1 and required αv-integrin or MMP for the response to recombinant latent TGF-β1. In keratinocyte-conditioned medium, MMP-dependent latent TGF-β1 secretion was detected. Applying this medium to the fibroblast culture enhanced α-SMA production. This effect was decreased by GM6001, the anti-αv-integrin antibody, or the preabsorption of latent TGF-β1. These results indicate that keratinocytes secrete latent TGF-β1, which is liberated to fibroblasts over distance and is activated to produce α-SMA with the aid of a positive-feedback loop. MMP inhibition was effective for targeting both keratinocytes and fibroblasts in this model.
Department of Oral Growth & Development, Fukuoka Dental College, Japan.
Shozaburo
S
Hata
Kazuhiko
K
Okamura
Mitsutoki
M
Hatta
Hiroyuki
H
Ishikawa
Jun
J
Yamazaki
D000199:Actins / Q000378:metabolism; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects*; D002478:Cells, Cultured; D002921:Cicatrix / Q000235:genetics / Q000473:pathology / Q000517:prevention & control; D004151:Dipeptides / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism / Q000473:pathology; D039482:Integrin alpha5 / Q000276:immunology; D015603:Keratinocytes / Q000378:metabolism*; D061965:Matrix Metalloproteinase Inhibitors / Q000494:pharmacology; D058628:Myofibroblasts / Q000473:pathology; D051381:Rats; D012867:Skin / Q000166:cytology*; D053773:Transforming Growth Factor beta1 / Q000378:metabolism / Q000494:pharmacology*; D014945:Wound Healing / Q000502:physiology*
D000199:Actins; D000906:Antibodies; D004151:Dipeptides; D039482:Integrin alpha5; D061965:Matrix Metalloproteinase Inhibitors; D053773:Transforming Growth Factor beta1; C078131:N-(2(R)-2-(hydroxamidocarbonylmethyl)-4-methylpentanoyl)-L-tryptophan methylamide; C498862:Acta2 protein, rat