Involvement of oxidative stress on corneal epithelial alterations in a blink-suppressed dry eye.
OBJECTIVE
To investigate whether oxidative stress is involved in the etiology of the corneal disorder in blink-suppressed dry eye in a clinically relevant in vivo rat model.


METHODS
A series of treatments were performed under continuous exposure to low-humidity airflow. Rats were placed on a jogging board (JB) made of a plastic pipe for 7.5 h/d, and for 16.5 hours, they were placed in individual cages without a JB. This protocol was repeated for up to 30 days. Corneal surface alteration was evaluated by the score of punctate fluorescein staining. To assess oxidative stress status, the levels of damaged DNA, and the protein modification by reactive aldehydes in corneal epithelia were detected by immunohistochemistry, using 8-hydroxy-2-deoxyguanosine, 4-hydroxynonenal- and malondialdehyde-specific antibodies.


RESULTS
Significant increases in the fluorescein staining score were observed from days 1 to 30 compared with the initial value. The average score for the dry eye group was significantly increased compared with that for the nontreatment group at all time points throughout the experiment. Immunoreactivity of all oxidative stress markers increased in the dry eye treatment. Quantitative analysis of the positive-stained cells showed a significant increase in the number of positive cells after 10 and 30 days in the dry eye treatment group compared with the nontreatment group.


CONCLUSIONS
These results suggest a relationship between the accumulation of oxidative stress and the etiology of corneal epithelial alterations in blink-suppressed dry eye.
Nakamura
Shigeru
S
Research Center, Ophtecs Corporation, 156-5 Kamiyoshidai, Toyooka, Hyogo 668-0831, Japan. research3@ophtecs.co.jp
Shibuya
Michiko
M
Nakashima
Hideo
H
Hisamura
Ryuji
R
Masuda
Nozomi
N
Imagawa
Tomohiro
T
Uehara
Masato
M
Tsubota
Kazuo
K
D000080242:8-Hydroxy-2'-Deoxyguanosine; D000447:Aldehydes / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D015415:Biomarkers / Q000378:metabolism; D001767:Blinking; D002454:Cell Differentiation; D003849:Deoxyguanosine / Q000031:analogs & derivatives / Q000378:metabolism; D004195:Disease Models, Animal; D015352:Dry Eye Syndromes / Q000209:etiology* / Q000378:metabolism; D019573:Epithelium, Corneal / Q000378:metabolism / Q000473:pathology*; D005260:Female; D007124:Immunoenzyme Techniques; D020287:In Situ Nick-End Labeling; D008315:Malondialdehyde / Q000378:metabolism; D008856:Microscopy, Fluorescence; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000447:Aldehydes; D015415:Biomarkers; D017382:Reactive Oxygen Species; D008315:Malondialdehyde; D000080242:8-Hydroxy-2'-Deoxyguanosine; D010088:Oxidoreductases; D003849:Deoxyguanosine; C027576:4-hydroxy-2-nonenal