Mitchell D. McCartney

The Eicosanoid, 15-(S)-HETE, Stimulates Secretion of Mucin-like Glycoprotein by the Corneal Epithelium

Purpose. The eicosanoid, 15-(S)-hydroxyeicosa-5Z, 8Z-11Z, 13E-tetraenoic acid (15-(S)-HETE), is known to stimulate production of mucin glycoprotein by airway epithelium. This study investigated the effect of 15-(S)-HETE on the mucin glycoprotein secretion by the corneal epithelium. Methods. To determine the effect of dose, corneas of anesthetized New Zealand White rabbits were treated with 50, 500, or 5,000 nM 15-(S)-HETE in artificial tears for 120 minutes. To determine the time to onset of the response, corneas were treated with 500 or 1,000 nM 15-(S)-HETE in balanced salt solution for periods ranging from 5 to 120 minutes. Corneas were fixed for electron microscopy in fixative containing 0.5% cetylpyridinium chloride (CPC) to stabilize the layer of mucin-like glycoprotein on the corneal surface. The mucin layer thickness was measured by image analysis of electron micrographs. Results. The layer of CPC-fixed mucin-like glycoprotein on the surface of control corneas was 0.46 ± 0.04 &mgr;m thick. After treatment with 15-(S)-HETE, the thickness of the mucin layer increased to 0.64 ± 0.1 &mgr;m at 50 or 5,000 nM HETE and as much as 1.02 ± 0.2 &mgr;m in response to 500 nM HETE. Mucin thickness reached a statistical maximum of 0.59 ± 0.1 &mgr;m after only 5 minutes of exposure to 500 or 1,000 nM HETE. Conclusions. Exposure of the cornea to 15-(S)-HETE causes a rapid-onset increase in the thickness of a layer of mucin-like glycoprotein on the surface of the corneal epithelium. This supports previous reports that corneal epithelial cells produce mucin and suggests that treatment with topical 15-(S)-HETE may be effective in treating ocular surface mucin deficiency in dry eye syndrome.

Topically applied 15-(S)-HETE stimulates mucin production by corneal epithelium.

Mucin is an important tear film component that adheres to ocular surface epithelium and is dissolved in the tear fluid. In addition to conjunctival goblet cells, mucin is also produced by ocular surface epithelial cells: MUC1 and MUC4 are produced by the conjunctiva, and MUC1 is produced by the cornea.1,2

The effects of moxifloxacin ophthalmic solution 0.5% or gatifloxacin ophthalmic solution 0.3% treatment on corneal wound healing in pigmented rabbits following anterior keratectomy

PURPOSE These studies examined corneal healing rates, Type-IV collagen and zonula occludens membrane-associated protein (ZO-1) expression, as well as aqueous PGE(2) and IL-1 beta concentrations in pigmented rabbits treated with either moxifloxacin 0.5%, gatifloxacin 0.3% or BSS following anterior keratectomy. METHODS Anterior keratectomy surgery was followed by topical administration with commercial ophthalmic formulations of either moxifloxacin or gatifloxacin or BSS (TID for 96 h). Images of the fluorescein-stained healing corneas were analyzed for wound area. At 48 or 96 h following surgery, aqueous humor samples were collected and analyzed for the inflammatory mediators PGE(2) and IL-1 beta using an ELISA. The corneas were subsequently evaluated using both scanning and transmission electron microscopy. In a second parallel study, corneas were evaluated at both 48 and 96 h for Type-IV collagen and ZO-1 expression using immunohistochemistry. RESULTS Fluorescein-stained corneal images at 96 h postsurgery demonstrated that 90% +/- 8% re-epithelialization for moxifloxacin, 81% +/- 14% for gatifloxacin, and 88 +/- 6% for BSS((R)) (P > 0.05). PGE(2 )levels in the aqueous humor of fluoroquinolone treated eyes were reduced at 48 h compared to BSS treated eyes. IL-1 beta was undetectable in all samples. No differences in Type-IV collagen or ZO-1 expression were observed between any treatment groups. There were no differences between groups in histological appearance or in ultrastructural healing processes. CONCLUSIONS These studies demonstrated that the commercial ophthalmic formulations of moxifloxacin and gatifloxacin were similar to each other in their effects on the levels of aqueous humor PGE(2) and rates of corneal wound re-epithelialization.

Comparison of wound healing in pigmented rabbits receiving moxifloxacin or gatifloxacin after creation of corneal flap or penetrating corneal incision

Purpose: Corneal wound healing was compared with topical ocular applications of moxifloxacin ophthalmic solution 0.5%, gatifloxacin ophthalmic solution 0.3%, or BSS Sterile Irrigating Solution after a 6-mm penetrating corneal incision during a 1-week observation period or after creation of a corneal flap during a 3-week observation period. Methods: Fifteen pigmented rabbits were randomized into 3 test groups of 5 rabbits per group (group 1, moxifloxacin 0.5%; group 2, gatifloxacin 0.3%; group 3, BSS Sterile Irrigating Solution). All animals underwent surgery using a microkeratome to create a corneal flap approximately 8.5 mm in diameter and 160 μm deep in the right eye (OD). The animals were dosed 4 times a day with the appropriate test article for 7 days after surgery. Biomicroscopic examinations and postmortem histopathology were conducted to compare the different treatments. In a second study, 9 pigmented rabbits were divided into 3 test groups of 3 rabbits per group. Each animal underwent bilateral surgery to create a 6-mm linear, penetrating incision into the central cornea, using a diamond keratome. The wound was subsequently sutured, and the animals were treated bilaterally (topical ocular) for 7 days with moxifloxacin (3 times a day), gatifloxacin (4 times a day), or BSS Sterile Irrigating Solution (4 times a day). On day 7, the left eye (OS) of each animal was processed and analyzed using standard hematoxylin-eosin histopathology, whereas the right eye of each animal underwent processing and analysis using scanning and transmission electron microscopy. Corneas were examined to evaluate wound healing progress, including the epithelial plug, cellular infiltrates, and stromal precipitates. Results: For both the corneal flap and linear incision studies, no appreciable differences were noted between groups with regard to slit-lamp or histopathologic examinations. In the linear incision study, electron microscopy revealed normal remodeling processes in all treatment groups, with no evidence of abnormal electron densities of the basal epithelial cells, basement membrane, anchoring filaments, collagen fibrils, extracellular matrix, or stromal keratocytes. Conclusions: Results showed that moxifloxacin and gatifloxacin were not significantly different from BSS in their effects on corneal wound healing and corneal haze after creation of both superficial and penetrating corneal wounds.

Association Between Corneal Endothelial Cell Density and Topical Glaucoma Medication Use in an Eye Bank Donor Population

Purpose: To evaluate the association between corneal endothelial cell density (ECD) and donor topical glaucoma medication use in an eye bank database. Methods: Raw eye bank data included 19,159 donors over the period July 2007 to May 2015. Free-text, donor medication lists were retrospectively searched for glaucoma medication. Exclusion criteria were age less than 40 years, history of eye surgery, endothelial trauma, guttae, and cell densities <1000 or >3300/mm2. Analysis of covariance was used to test differences in cell density between groups while adjusting for age. Linear regression was used to test the correlation of independent interval variables while adjusting for age. Results: Twelve thousand one hundred fifty-seven donors were included in the final analysis; 134 were on topical glaucoma medication. The mean ECD for donors not on glaucoma medication and pooled donors on glaucoma medication was 2561 ± 348 and 2516 ± 320 cells/mm2, respectively (P = 0.42). Subgroup analysis by medication class resulted in nonstatistically significant differences between ECDs of nonmedicated donors and donors on alpha agonists (P = 0.76), beta blockers (P = 0.90), carbonic anhydrase inhibitors (P = 0.13), cholinergics (P = 0.37), and prostaglandin analogs (P = 0.62). The number of glaucoma medication classes used by donors was not a statistically significant predictor of endothelial density (P = 0.298). Conclusions: Donors on topical glaucoma medication do not have ECDs statistically significantly lower than donors not on medication.

Technician Consistency in Specular Microscopy Measurements: A “Real-World” Retrospective Analysis of a United States Eye Bank

Purpose: To quantify consistency of endothelial cell density (ECD) measurements among technicians in a single US eye bank operating under typical operating conditions. Methods: In this retrospective analysis of 51 microscopy technicians using a semiautomated counting method on 35,067 eyes from July 2007 to May 2015, technician- and date-related marginal ECD effects were calculated using linear regression models. ECD variance was correlated with the number of specular microscopy technicians. Results: Technician mean ECDs ranged from 2386 ± 431 to 3005 ± 560 cells/mm2. Nine technicians had statistically and clinically significant marginal effects. Annual mean ECDs adjusted for changes in technicians ranged from 2422 ± 433 to 2644 ± 430 cells/mm2. The period of 2007 to 2009 had statistically and clinically significant marginal effects. There was a nonstatistically significant association between the number of technicians and ECD standard deviation. Conclusions: There was significant ECD variability associated with specular microscopy technicians and with the date of measurement. We recommend that eye banks collect data related to laboratory factors that have been shown to influence ECD variability.