Vitamin D: a novel therapeutic approach for keloid, an in vitro analysis.
BACKGROUND
Vitamin D and its metabolites play an important role in calcium homeostasis, bone remodelling, hormone secretion, cell proliferation and differentiation. Recent studies also suggest a beneficial role of vitamin D in slowing the progression of tissue fibrosis. However, their effects on dermal fibrosis and keloids are unknown. Objectives  To investigate the effect of 1,25-dihydroxyvitamin D3 (1,25D) in the pathogenesis of tissue fibrosis by keloid fibroblasts (KFs).


METHODS
KFs were cultured and exposed to different concentrations of 1,25D in the presence or absence of transforming growth factor (TGF)-β1. KF phenotypes and protein production were analysed by real-time reverse transcriptase-polymerase chain reaction, Western blot, immunofluorescence and multiplex enzyme-linked immunosorbent assay techniques. Collagen synthesis was evaluated by measuring (3) H-proline incorporation. The effect of 1,25D on cell proliferation and viability was evaluated by Formazan assay, proliferating cell nuclear antigen expression and the colorimetric conversion of 3-[4, 5-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide.


RESULTS
We confirmed the presence of vitamin D receptors (VDRs) in cultured keloid fibroblasts. Fibroblasts transfected with a vitamin D response element reporter construct and exposed to the active vitamin D metabolite 1,25D showed increased promoter activity indicating VDR functionality in these cells. Incubation of KFs with 1,25D suppressed TGF-β1-induced collagen type I, fibronectin and α-smooth muscle actin expression. 1,25D also modulated plasminogen activator inhibitor-1 and matrix metalloproteinase-9 expression induced by TGF-β1. Interestingly, 1,25D induced hepatocyte growth factor mRNA expression and protein secretion in keloid fibroblasts.


CONCLUSIONS
This study highlights key mechanistic pathways through which vitamin D decreases fibrosis, and provides a rationale for studies to test vitamin D supplementation as a preventive and/or early treatment strategy for keloid and related fibrotic disorders.
Department of Hand and Plastic Surgery, the 2nd Affiliated Hospital of Wenzhou Medical College, Xueyuan West Road 109, Wenzhou 325027, Zhejiang Province, China. guoyou.zhang@yahoo.com
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Zhang
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Luan
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Liao
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Zheng
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Gao
D000293:Adolescent; D000328:Adult; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured / Q000187:drug effects; D003094:Collagen / Q000378:metabolism; D004100:Dihydroxycholecalciferols / Q000494:pharmacology*; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D017228:Hepatocyte Growth Factor / Q000378:metabolism; D006801:Humans; D007163:Immunosorbent Techniques; D007627:Keloid / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D008297:Male; D010641:Phenotype; D018167:Receptors, Calcitriol / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D014815:Vitamins / Q000494:pharmacology*; D055815:Young Adult
D004100:Dihydroxycholecalciferols; D018167:Receptors, Calcitriol; D053773:Transforming Growth Factor beta1; D014815:Vitamins; C023850:1 alpha,24-dihydroxyvitamin D3; D017228:Hepatocyte Growth Factor; D003094:Collagen