Expression of type XVIII collagen during healing of corneal incisions and keratectomy wounds.
OBJECTIVE
To determine the distribution of type XVIII collagen in mouse ocular tissues and to investigate the expression of type XVIII collagen during healing of corneal incisions and keratectomy wounds.


METHODS
Immunohistochemical analysis of type XVIII collagen was performed in mouse ocular tissue, with polyclonal antibodies to the hinge domain. For wound-healing experiments, excimer laser keratectomy and single linear incisions were performed on mouse corneas. The corneas were harvested at various time points after wounding and processed for immunohistochemistry, in situ hybridization, competitive reverse transcription-polymerase chain reaction (RT-PCR), and Western blot analysis.


RESULTS
In the unwounded mouse cornea, type XVIII collagen was expressed by the corneal epithelial cells. Type XVIII collagen was immunolocalized to the mouse corneal epithelium, epithelial basement membrane, Descemet's membrane, ciliary epithelium, lens capsule, retinal inner limiting membrane, and Bruch's membrane. In the early stages of wound healing after excimer laser keratectomy (days 3 and 7), type XVIII collagen staining of the epithelial basement membrane was absent, whereas its localization to Descemet's membrane was unchanged. After linear corneal incisions, however, type XVIII collagen was clearly seen in the stroma and in the epithelial basement membrane. Type XVIII collagen immunolocalization to the subepithelial stromal wound region peaked at 1 week after wounding, and its mRNA showed a corresponding temporal increase in expression within the same region after linear corneal incisions.


CONCLUSIONS
The results suggest that type XVIII collagen is broadly expressed in ocular tissues and that it may have a role in wound healing, especially after incisional corneal wounds.
Kato
Takuji
T
Massachusetts Eye and Ear Infirmary and the Schepens Eye Research Institute, Harvard Medical School, 243 Charles Street, Boston, MA 02114, USA.
Chang
Jin-Hong
JH
Azar
Dimitri T
DT
D000818:Animals; D001485:Basement Membrane / Q000378:metabolism; D015153:Blotting, Western; D002924:Ciliary Body / Q000378:metabolism; D003094:Collagen / Q000235:genetics / Q000378:metabolism*; D043170:Collagen Type XVIII; D003315:Cornea / Q000378:metabolism* / Q000601:surgery; D065306:Corneal Injuries; D003886:Descemet Membrane / Q000378:metabolism; D019573:Epithelium, Corneal / Q000378:metabolism; D005260:Female; D017403:In Situ Hybridization; D054018:Lasers, Excimer; D007903:Lens Capsule, Crystalline / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D018903:Photorefractive Keratectomy; D012333:RNA, Messenger / Q000378:metabolism; D012160:Retina / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014945:Wound Healing
D043170:Collagen Type XVIII; D012333:RNA, Messenger; D003094:Collagen