Lacrimal gland HGF, KGF, and EGF mRNA levels increase after corneal epithelial wounding.
OBJECTIVE
To evaluate the effect of corneal epithelial wounding on lacrimal gland expression of hepatocyte growth factor (HGF), keratinocyte growth factor (KGF), and epidermal growth factor (EGF) in the rabbit model.


METHODS
Rabbits had corneal epithelial scrape injuries, and the lacrimal gland was removed at different times after wounding. HGF, KGF, and EGF mRNA expression was examined by quantitative RNase protection assay. HGF, KGF, and EGF proteins were detected in rabbit lacrimal tissue using immunoprecipitation and western blot analysis.


RESULTS
HGF mRNA and EGF mRNA were significantly increased in rabbit lacrimal gland tissue within 8 hours after corneal epithelial injury. The increase in KGF mRNA expression was small and reached significance I clay after corneal injury. Lacrimal gland expression peaked at 3 days after wounding for each growth factor mRNA, the same day, on average, that the epithelial defect healed. After the peak increase in expression, there was a progressive decline in expression of each growth factor mRNA, but production was still increased compared with prewound levels. HGF protein, KGF protein, and EGF proteins were detected in rabbit lacrimal gland tissue.


CONCLUSIONS
Levels of HGF, KGF, and EGF mRNAs increase in rabbit lacrimal gland tissue in response to corneal epithelial wounding. The results of this study are consistent with the existence of a cornea-nervous system-lacrimal gland regulatory loop modulating expression of these growth factor mRNAs. The lacrimal gland is a likely source of increased HGF and EGF proteins detected in tears in previous studies.
Wilson
S E
SE
Department of Ophthalmology, University of Washington School of Medicine, Seattle 98195-6485, USA. sewilson@u.washington.edu
Liang
Q
Q
Kim
W J
WJ
D000818:Animals; D015153:Blotting, Western; D017931:DNA Primers / Q000737:chemistry; D004815:Epidermal Growth Factor / Q000235:genetics* / Q000378:metabolism; D019573:Epithelium, Corneal / Q000293:injuries*; D051526:Fibroblast Growth Factor 10; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors; D006133:Growth Substances / Q000235:genetics* / Q000378:metabolism; D017228:Hepatocyte Growth Factor / Q000235:genetics* / Q000378:metabolism; D007765:Lacrimal Apparatus / Q000378:metabolism*; D011233:Precipitin Tests; D012333:RNA, Messenger / Q000378:metabolism*; D011817:Rabbits; D014945:Wound Healing
D017931:DNA Primers; D051526:Fibroblast Growth Factor 10; D006133:Growth Substances; D012333:RNA, Messenger; D051523:Fibroblast Growth Factor 7; D005346:Fibroblast Growth Factors; D004815:Epidermal Growth Factor; D017228:Hepatocyte Growth Factor