Modulation of matrix metalloproteinases by ultraviolet radiation in the canine cornea.
OBJECTIVE
To determine whether ultraviolet (UV) radiation can modulate expression and regulation of matrix metalloproteinases (MMP) in the canine cornea and to examine the expression of MMPs in canine chronic superficial keratitis (CSK).


METHODS
Immunohistochemistry for MMP-2 and MMP-9 was performed on samples of CSK. In vitro, canine corneal epithelial cell (CEC) and stromal cell cultures were exposed to UV-irradiation. Following 2, 8 or 24 h, cells were harvested. MMP expression was examined by zymography, and RT-PCR was used to examine expression of Slug and Snail. CEC cultures treated with an EGFR inhibitor or a p38 inhibitor were UV-exposed and harvested 24 h later to examine expression of MMPs, Slug and Snail.


RESULTS
Canine CSK had increased immunopositivity for both MMP-2 and MMP-9 compared to normal canine corneas. In vitro, CEC and stromal cell cultures exposed to UV showed generally increased expression of MMP-2, -9, Slug, and Snail; this response was dose and time dependent. Inhibition of the EGFR pathway did not prevent increased expression of MMP-2, -9, Slug or Snail in UV-exposed CEC; however, p38 inhibition did attenuate UV induction.


CONCLUSIONS
We have found increased expression of MMPs in clinical samples of CSK compared to normal corneas. In addition, we have shown that there is a temporal association and dose dependency between UV exposure and production of MMPs, Slug, and Snail. These findings suggest that overexpression of MMPs due to UV-exposure may be linked to changes in the cornea that allow an influx of inflammatory cells and vascularization.
Chandler
Heather L
HL
Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, 1900 Coffey Road, Columbus, OH 43201, USA. chandler.111@osu.edu
Kusewitt
Donna F
DF
Colitz
Carmen M H
CM
D000818:Animals; D018929:Cell Culture Techniques; D003315:Cornea / Q000201:enzymology* / Q000378:metabolism; D004283:Dog Diseases / Q000201:enzymology / Q000532:radiotherapy; D004285:Dogs; D004307:Dose-Response Relationship, Radiation; D007150:Immunohistochemistry / Q000662:veterinary; D007634:Keratitis / Q000201:enzymology / Q000532:radiotherapy / Q000662:veterinary; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism / Q000528:radiation effects; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism / Q000528:radiation effects; D020782:Matrix Metalloproteinases / Q000378:metabolism* / Q000528:radiation effects*; D013997:Time Factors; D019714:Tissue Inhibitor of Metalloproteinases / Q000378:metabolism*; D014466:Ultraviolet Rays
D019714:Tissue Inhibitor of Metalloproteinases; D020782:Matrix Metalloproteinases; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9