Effects of transforming growth factor beta on corneal epithelial and stromal cell function in a rat wound healing model after excimer laser keratectomy.
BACKGROUND
Transforming growth factor beta (TGF-beta) regulates extracellular matrix deposition, cell proliferation, and migration, and is expressed in cornea. TGF-beta is thought to be involved in the corneal wound healing process.


METHODS
The central corneal area (3 mm in diameter) of Lewis rats was ablated using PTK mode excimer laser and the wound healing process was observed at 12 and 24 h and 2, 5, 10, and 30 days after treatment. The expression of TGF-beta 1, -beta 2 and -beta 3, TGF-beta type I and type II receptors, alpha 3, alpha 5, beta 4 integrin subunits, laminin and fibronectin was studied immunohistochemically. Antibody neutralizing TGF-beta 1, -beta 2 and -beta 3 was administered intraperitoneally, 50 micrograms daily, for 5 days after the laser treatment to investigate the effects of TGF-beta function blockade.


RESULTS
At the leading edge of the regenerating epithelium, no TGF-beta type I and type II receptors and beta 4 integrin subunits were expressed after 24 h. Regenerating epithelium covered the ablated area after 2 days. An abnormal fibrotic layer was formed in the subepithelial area. This layer contained round-shaped cells in the stroma in the early stage (2-5 days after laser ablation) and spindle-shaped fibroblast-like keratocytes after 10 days. Laminin and fibronectin expression increased in the fibrotic layer. The increased stromal cells expressed TGF-beta isoforms and TGF-beta receptors. Neutralizing TGF-beta inhibited the stromal cell increase in the laser ablated area after 5 days.


CONCLUSIONS
TGF-beta may be involved in epithelial cell migration and stromal cell reaction during the corneal wound healing process after excimer laser ablation in rat models.
Mita
T
T
Department of Ophthalmology, Toho University School of Medicine, Tokyo, Japan.
Yamashita
H
H
Kaji
Y
Y
Obata
H
H
Yamada
H
H
Kato
M
M
Hanyu
A
A
Suzuki
M
M
Tobari
I
I
D030201:Activin Receptors, Type I; D000818:Animals; D002465:Cell Movement; D003315:Cornea / Q000601:surgery; D003319:Corneal Stroma / Q000502:physiology*; D019573:Epithelium, Corneal / Q000502:physiology*; D005353:Fibronectins / Q000378:metabolism; D007124:Immunoenzyme Techniques; D007136:Immunoglobulins / Q000008:administration & dosage; D007274:Injections, Intraperitoneal; D016023:Integrins / Q000378:metabolism; D007797:Laminin / Q000378:metabolism; D054018:Lasers, Excimer; D018903:Photorefractive Keratectomy; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051381:Rats; D011917:Rats, Inbred Lew; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000276:immunology / Q000502:physiology*; D014945:Wound Healing / Q000502:physiology
D005353:Fibronectins; D007136:Immunoglobulins; D016023:Integrins; D007797:Laminin; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; C000625843:Tgfbr1 protein, rat