Desiccating stress decreases apical corneal epithelial cell size--modulation by the metalloproteinase inhibitor doxycycline.
OBJECTIVE
We investigated the effects of desiccating stress on murine corneal apical epithelial cell area and desquamation by using 4 defined parameters and evaluated the effects of the metalloproteinase inhibitor doxycycline on this process.


METHODS
C57BL/6 mice were subjected to experimental dry eye (EDE) for 5 days without or with topical therapy with doxycycline 0.025% or 0.0025% or vehicle 4 times a day. C57BL/6 mice that were not exposed to desiccating stress served as controls. Whole mount corneas from each group were immunostained for occludin and visualized by laser scanning confocal microscopy. The images were analyzed in a masked fashion, and mean individual cell area, apical cell density, average cell number loss, and average percent loss were recorded.


RESULTS
EDE caused a significant decrease in apical corneal cell area (1073 +/- 135.9 microm2), an increase in apical cell density (895.8 +/- 115.4 cells per mm2) and a greater percent of epithelial loss (21.29% +/- 13.40%) than controls (1341 +/- 95.28 microm2, 714.4 +/- 55.60 cells per mm2, 2.897% +/- 3.452%, P < 0.001 for all, respectively). Treatment with 0.025% doxycycline preserved cell area (1337 +/- 144.6 microm2) and the apical cell density (721.0 +/- 91.62 cells per mm2) and decreased percentage loss (5.117% +/- 6.757%) compared with the vehicle control group (1154 +/- 88.10 microm2, 830.2 +/- 49.76 cells per mm2, 22.14 +/- 9.616%, P < 0.001 for all, respectively).


CONCLUSIONS
Desiccating stress decreases apical corneal epithelial cell area, increases apical cell density, and promotes epithelial cell loss. Treatment with the metalloproteinase inhibitor doxycycline during desiccating stress preserves cell area and apical cell density and prevents EDE-induced corneal epithelial cell loss. These findings suggest that metalloproteinases mediate apical corneal epithelial loss during desiccating stress.
Beardsley
Robert M
RM
Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston, TX, USA.
De Paiva
Cintia S
CS
Power
David F
DF
Pflugfelder
Stephen C
SC
D000818:Animals; D002452:Cell Count; D048429:Cell Size / Q000187:drug effects*; D003890:Desiccation; D004195:Disease Models, Animal; D004318:Doxycycline / Q000627:therapeutic use*; D015352:Dry Eye Syndromes / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D019573:Epithelium, Corneal / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005260:Female; D008297:Male; D061965:Matrix Metalloproteinase Inhibitors; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D062793:Occludin
D061965:Matrix Metalloproteinase Inhibitors; D008565:Membrane Proteins; D062793:Occludin; C568986:Ocln protein, mouse; D004318:Doxycycline