Connective tissue growth factor expression and action in human corneal fibroblast cultures and rat corneas after photorefractive keratectomy.
OBJECTIVE
Connective tissue growth factor (CTGF) has been linked to fibrosis in several tissues. In this study, the interactions between CTGF and transforming growth factor (TGF)-beta were assessed in human corneal fibroblasts, and the levels and location of CTGF protein and mRNA were measured during healing of excimer laser ablation wounds in rat corneas.


METHODS
Human corneal fibroblasts were incubated with TGF-beta1, -beta2, and -beta3 isoforms, and CTGF mRNA and protein were measured. CTGF was immunolocalized in the cultured fibroblasts by using a specific antibody. Regulation of collagen synthesis by TGF-beta and CTGF was assessed in human corneal fibroblasts with a neutralizing antibody and an antisense oligonucleotide to CTGF. CTGF mRNA and protein were measured in rat corneas up to day 21 after excimer ablation of the cornea. CTGF protein was immunolocalized in rat corneas after photorefractive keratectomy (PRK), and the presence of CTGF mRNA and protein in ex vivo rat corneal scrapings was established.


RESULTS
All three TGF-beta isoforms stimulated expression of CTGF in human corneal fibroblasts, and CTGF was immunolocalized in the cells. Both TGF-beta and CTGF increased collagen synthesis in corneal fibroblasts. Furthermore, CTGF antibody or antisense oligonucleotide blocked TGF-beta-stimulated collagen synthesis. CTGF protein and mRNA increased in rat corneas through day 21 after PRK. CTGF expression was also detected in ex vivo scrapings of rat corneas.


CONCLUSIONS
These data demonstrate that CTGF is expressed by corneal cells after stimulation by TGF-beta, that CTGF expression increases significantly during corneal wound healing, and that CTGF mediates the effects of TGF-beta induction of collagen synthesis by corneal fibroblasts. These data support the hypothesis that CTGF promotes corneal scar formation and imply that regulating CTGF synthesis and action may be an important goal for reducing corneal scarring.
Blalock
Timothy D
TD
Institute for Wound Research, University of Florida, Gainesville, Florida 32610-0294, USA.
Duncan
Matthew R
MR
Varela
Juan C
JC
Goldstein
Michael H
MH
Tuli
Sonal S
SS
Grotendorst
Gary R
GR
Schultz
Gregory S
GS
D000818:Animals; D018929:Cell Culture Techniques; D003094:Collagen / Q000096:biosynthesis; D055513:Connective Tissue Growth Factor; D003315:Cornea / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000601:surgery; D004797:Enzyme-Linked Immunosorbent Assay; D005347:Fibroblasts / Q000378:metabolism; D006801:Humans; D017874:Immediate-Early Proteins / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D007124:Immunoenzyme Techniques; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D054018:Lasers, Excimer; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D018903:Photorefractive Keratectomy; D020033:Protein Isoforms; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000494:pharmacology; D014945:Wound Healing / Q000502:physiology*
C526317:CCN2 protein, human; C526316:CCN2 protein, rat; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D016376:Oligonucleotides, Antisense; D020033:Protein Isoforms; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D055513:Connective Tissue Growth Factor; D003094:Collagen