Apical corneal barrier disruption in experimental murine dry eye is abrogated by methylprednisolone and doxycycline.
OBJECTIVE
To evaluate the mechanism of apical corneal epithelial barrier disruption in response to experimental ocular surface desiccation and the effects of two anti-inflammatory agents (methylprednisolone and doxycycline) on this process.


METHODS
Experimental dry eye (EDE) was created in C57BL/6 mice, without or with topical therapy, 1% methylprednisolone, 0.025% doxycycline, or physiologic saline solution (PSS) four times per day. Corneal smoothness and Oregon green dextran (OGD) permeability were assessed. Desquamation of and cornified envelope protein (involucrin and small proline-rich protein [SPRR]-2) expression by the corneal epithelium was evaluated by laser scanning confocal microscopy. Levels of cornified envelope proteins mRNA were measured by real-time PCR.


RESULTS
Corneal OGD permeability, surface irregularity, and the number of desquamating apical corneal epithelia significantly increased in EDE. Desiccating stress significantly increased expression of involucrin and SPRR-2 in the corneal epithelia. Treatment of EDE with methylprednisolone or doxycycline reduced corneal permeability to OGD, improved corneal smoothness, and decreased involucrin and SPRR-2 immunoreactivity compared with EDE+PSS.


CONCLUSIONS
Disruption of apical corneal epithelial barrier function in dry eye is accompanied by increased apical desquamation and increased expression of cornified envelope proteins. Topical treatment of EDE with the anti-inflammatory agents methylprednisolone or doxycycline preserves apical corneal barrier function.
De Paiva
Cintia S
CS
Ocular Surface Center, Department of Ophthalmology, Cullen Eye Institute, Baylor College of Medicine, Houston, Texas 77030, USA.
Corrales
Rosa M
RM
Villarreal
Arturo L
AL
Farley
William
W
Li
De-Quan
DQ
Stern
Michael E
ME
Pflugfelder
Stephen C
SC
D000818:Animals; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D055233:Cornified Envelope Proline-Rich Proteins; 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; D019084:Fluorescent Antibody Technique, Indirect; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008775:Methylprednisolone / Q000627:therapeutic use*; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D062793:Occludin; D009930:Organic Chemicals / Q000378:metabolism; D010539:Permeability / Q000187:drug effects; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D011503:Transglutaminases / Q000378:metabolism
D000893:Anti-Inflammatory Agents; D055233:Cornified Envelope Proline-Rich Proteins; D008565:Membrane Proteins; D062793:Occludin; C568986:Ocln protein, mouse; C403124:Oregon Green BAPTA-dextran; D009930:Organic Chemicals; D011498:Protein Precursors; D012333:RNA, Messenger; C491091:Sprr2a1 protein, mouse; C032253:involucrin; D011503:Transglutaminases; C105804:transglutaminase 1; D004318:Doxycycline; D008775:Methylprednisolone