The leaves of Diospyros kaki exert beneficial effects on a benzalkonium chloride-induced murine dry eye model.
OBJECTIVE
In this study, the beneficial effects of the oral administration of ethanol extract of Diospyros kaki (EEDK) were tested on a mouse dry eye model induced by benzalkonium chloride (BAC).


METHODS
A solution of 0.2% BAC was administered topically to mouse eyes for 14 days, twice daily, to induce dry eye. Various concentrations of EEDK were administrated daily by oral gavage for 14 days after BAC treatment. Preservative-free eye drops were instilled in the positive-control group. The tear secretion volume (Schirmer's test), tear break-up time (BUT), and fluorescein score were measured on the ocular surface. BAC-induced corneal damage was tested with hematoxylin-eosin staining. Moreover, apoptotic cell death in the corneal epithelial layer was investigated with terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining. The protein expression level of interleukin-1alpha (IL-1α), IL-1β, IL-6, tumor necrosis factor- alpha (TNF-α), and monocyte chemotactic protein-1 (MCP-1) was determined with western blot analysis. Furthermore, squamous metaplasia in the corneal epithelial layer was detected with immunofluorescent staining for cytokeratine-10. The cellular proliferation in the cornea was examined with immunohistochemical staining for Ki-67.


RESULTS
EEDK treatment resulted in prolonged BUT, decreased fluorescein score, increased tear volume, and smoother epithelial cells compared with BAC treatment alone in the cornea. Moreover, EEDK treatment inhibited the inflammatory response and corneal epithelial cell death in a BAC-induced murine dry eye model, and changes in squamous cells were inhibited. Proliferative activity in the corneal epithelium cells was improved with EEDK.


CONCLUSIONS
EEDK could be a potential therapeutic agent in the clinical treatment of dry eye.
Natural Products Research Center, Korea Institute of Science and Technology (KIST), Gangneung, Korea; Department of Biological Chemistry, Korea University of Science and Technology (UST), Daejeon, Korea.
Kyung-A
KA
Kim
Department of Ophthalmology, University of Ulsan, Gangneung Asan Hospital, Gangneung, Korea.
Lee Chung
LC
Hyun
Natural Products Research Center, Korea Institute of Science and Technology (KIST), Gangneung, Korea; Department of Biological Chemistry, Korea University of Science and Technology (UST), Daejeon, Korea.
Sang Hoon
SH
Jung
Department of Ophthalmology, University of Ulsan, Gangneung Asan Hospital, Gangneung, Korea.
Sung Jae
SJ
Yang
D000284:Administration, Oral; D000818:Animals; D017209:Apoptosis; D001548:Benzalkonium Compounds / Q000633:toxicity; D015153:Blotting, Western; D003315:Cornea / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D016207:Cytokines / Q000378:metabolism; D029788:Diospyros / Q000737:chemistry*; D004195:Disease Models, Animal; D015352:Dry Eye Syndromes / Q000139:chemically induced / Q000188:drug therapy* / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D020287:In Situ Nick-End Labeling; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009883:Ophthalmic Solutions; D010936:Plant Extracts / Q000008:administration & dosage*; D018515:Plant Leaves / Q000737:chemistry*; D013666:Tears / Q000502:physiology
D001548:Benzalkonium Compounds; D016207:Cytokines; D009883:Ophthalmic Solutions; D010936:Plant Extracts