Duration 5min, Q&A 3min
Therapeutic Effect of Topical Doxycycline in a Mouse Model of Benzalkonium Chloride-Induced Dry Eye
Orally administered doxycycline has been applied to treat ocular surface inflammatory diseases such as meibomian gland dysfunction, however, topical medication is a more ideal treatment for the dry eye disease. In this study, we aimed to investigate the therapeutic effect and underlying mechanisms of topical doxycycline in a mouse model of benzalkonium chloride (BAC)-induced dry eye.
A total of 35 male BALB/c mice (18-20 g) were used in this study.
After the experimental dry eye was induced by BAC for 14 days, eye drops containing 0.025%, 0.1% doxycycline, or solvent were topically administered four times daily. The clinical evaluations of dry eye including tear break-up time (BUT), corneal fluorescein staining, inflammatory index, and tear volume were performed on Day 0, 1, 4, 7, and 10. Global specimens were collected on Day 10 and then the following examinations were performed: immunofluorescence staining for Ki-67, keratin 10 (K10), and CD11b in corneas, TUNEL assay to measure apoptotic cells, periodic acid-Schiff (PAS) assay to detect goblet cells. Levels of matrix metalloproteinase-9 (MMP-9), interleukin (IL)-1α, IL-1β, IL-6, IL-8, and tumor necrosis factor (TNF)-α in corneas were determined by real-time PCR. The total and phosphorylated Akt and nuclear factor-κB (NF-κB) were detected by western blot.
Results and Conclusion
Both 0.025% and 0.1% doxycycline treatments resulted in longer BUT, lower fluorescein staining scores and inflammatory index on Day 4, 7, and 10, while no significant change in tear volume. The 0.1% doxycycline-treated group showed more improvement in decreasing fluorescein staining scores, increasing Ki-67 positive cells, and decreasing TUNEL and K10 positive cells than the other groups. The goblet cells in conjunctivas were increased, and the expression of CD11b and levels of pro-inflammatory cytokines in corneas were decreased in both doxycycline-treated groups. In addition, doxycycline significantly reduced the phosphorylation of Akt and NF-κB activated in BAC-treated corneas. Taken together, our data showed that topical application of doxycycline ameliorated clinical symptoms of dry eye by promoting cell proliferation, preventing apoptosis and squamous metaplasia of the corneal epithelium, stabilizing the tear film, and suppressing the ocular surface inflammation. We suggest a great potential for doxycycline as a topical therapeutic agent in the clinical treatment of dry eye and propose that the underlying mechanisms involve the inhibition of Akt and NF-κB activation.
[ Keyword ]
doxycycline / dry eye / topical application / mouse model / benzalkonium chloride
[ Conflict of Interest ]