Atsuko Fujii

Bepotastine besilate, a highly selective histamine H1 receptor antagonist, suppresses vascular hyperpermeability and eosinophil recruitment in in vitro and in vivo experimental allergic conjunctivitis models

To elucidate the ocular pharmacological properties of bepotastine besilate, a selective histamine H(1) receptor antagonist, when compared with other histamine H(1) receptor antagonists, using guinea pig allergic conjunctivitis models and in vitro models of eosinophil recruitment and mast cell membrane stabilization. Conjunctival vascular hyperpermeability was studied in guinea pigs passively sensitized with anti-ovalbumin antiserum or following subconjunctival injection of histamine. Modulation of eosinophil recruitment was evaluated for both platelet-activating factor (PAF)-induced eosinophil infiltration in guinea pigs and leukotriene B(4)-induced in vitro chemotaxis of guinea pig peritoneal eosinophils. Membrane-stabilizing effects of bepotastine also were studied with rat peritoneal mast cells stimulated with the ionophore A23187. Histamine H(1) receptor antagonists including bepotastine besilate were topically administered before ovalbumin, histamine or PAF challenges for in vivo experiments or were added directly to mast cell and eosinophil medium in vitro. Bepotastine besilate significantly inhibited conjunctival vascular hyperpermeability in a dose-dependent manner with maximal effect for bepotastine besilate 1.5%. In separate in vivo experiments, bepotastine besilate 1.0% was significantly more effective than levocabastine 0.025% in the passive sensitization model or olopatadine 0.1% in the histamine-induced hyperpermeability model. Bepotastine besilate 1.0% further suppressed PAF-induced eosinophil infiltration into conjunctival tissue more effectively than ketotifen 0.05%. Chemotaxis of guinea pig peritoneal eosinophils and histamine release from rat peritoneal mast cells in vitro were also inhibited by addition of bepotastine. Olopatadine had a weak effect as compared to that of bepotastine on eosinophil chemotaxis and no effect on mast cell histamine release in our study conditions. Bepotastine besilate was more potent than olopatadine, ketotifen, or levocabastine in reducing vascular hyperpermeability in various animal models of allergic conjunctivitis. Mast cell function and eosinophil chemotaxis were also inhibited in vitro with bepotastine, suggesting bepotastine acts as an inhibitor of allergic response through multiple mechanisms: histamine H(1) receptor antagonism, mast cell stabilization, and inhibition of eosinophil migration to ocular inflammatory sites.

Galectin-3 Enhances Epithelial Cell Adhesion and Wound Healing in Rat Cornea

Background/Aims: To investigate if galectin-3: (1) enhances adhesion of rat corneal epithelial cells onto a collagen IV substrate and (2) promotes wound healing in rat corneal explants. Methods: Primary cultures of rat corneal epithelial cells were fixed and immunostained with galectin-3 antibody. To test cellular adherence onto plates coated with collagen type IV, isolated corneal epithelial cells from rats were cultured for 24 h with or without recombinant galectin-3. The attached cells were counted after fixing and staining with 0.1% crystal violet. Direct binding of galectin-3 to collagen IV was tested using a biotin label transfer method. To evaluate wound healing, explants with a 3.5-mm diameter wound in the central corneal epithelium from rats were incubated for 16 h with or without recombinant galectin-3. Changes in the size of the wound were measured with a digital microscope after staining with 5% fluorescein sodium. Results: In rat corneal epithelial cells, galectin-3 was stained throughout the cytoplasm, with increasing density adjacent to the plasma membrane. Exogenous galectin-3, but not epidermal growth factor (EGF), significantly promoted adhesion of corneal epithelial cells onto the collagen IV substrate. Galectin-3 directly bound to collagen IV in vitro. Exogenous galectin-3 significantly enhances wound healing in the corneal explants, which was partially inhibited by β-lactose. Conclusion: Galectin-3 promotes adhesion of corneal epithelial cells onto collagen IV and enhances wound healing in corneal explants. Since galectin-3 functions in promoting wound healing by a different mechanism than that used by EGF, exogenous galectin-3 may be a candidate drug for enhancing epithelial cell wound healing in disorders of the cornea.

Galectin-3 enhances extracellular matrix associations and wound healing in monkey corneal epithelium.

Poor healing of epithelial wounds in cornea is a major clinical problem, leading to persistent epithelial defects and ulceration. The primary cause is poor cell migration over the wound. Carbohydrate-binding protein galectin-3 binds to extracellular matrixes (ECMs) and promotes lamellipodia formation by cross-linking to α3 integrin. Recombinant galectin-3 also facilitates wound healing in the rodent cornea. The purposes of the present experiments were to: (1) establish epithelial wound healing models in monkey corneal explant culture, the models more relevant to human, (2) evaluate the healing effect of galectin-3 in our models, and (3) determine if galectin-3 enhances cell adhesion by interacting with ECMs on corneal surface and their ligand integrins. Monkey corneas with central wounds produced by sodium hydroxide (NaOH) or n-heptanol were incubated with or without recombinant galectin-3. The defected area was stained with sodium fluorescein. Primary isolated corneal epithelial cells from monkey were cultured with or without galectin-3 on plates coated with ECMs or integrins, and the number of adhering cells was counted. Galectin-3 expression in various eye tissues was visualized by immunoblotting. NaOH caused loss of epithelial cells and basement membrane. n-Heptanol removed epithelial cells, but the basement membrane was retained. These corneal defects spontaneously became smaller in a time-dependent manner. Exogenous galectin-3 enhanced wound healing in both NaOH and n-heptanol models. Galectin-3 also enhanced cell adhesion onto the major ECMs found in the basement and Bowmans membranes and onto integrins. Relatively high levels of galectin-3 were detected in corneal and conjunctival epithelium, but tear fluid contained negligible galactin-3. These results suggested that the enhanced binding of epithelial cells to ECMs and integrins caused by galectin-3 might promote cell migration over wounded corneal surfaces. Since tear fluid contained relatively low levels of galectin-3, exogenous galectin-3 may be a beneficial drug to enhance re-epithelialization in human corneal diseases.

Lacritin-Induced Secretion of Tear Proteins From Cultured Monkey Lacrimal Acinar Cells

PURPOSE During inflammation of the ocular surface, increased proinflammatory cytokines depress tear protein secretion, suggesting that a decline in lacrimal cell function contributes to dry eye. Lacritin, a glycoprotein secreted from lacrimal acinar cells, may function as an autocrine factor to stimulate tear protein secretion. The purpose of the present experiment was to investigate lacritin-induced protein secretion in normal and cytokine-pretreated (inflammation model) monkey acinar cells. METHODS Acinar cells from monkey lacrimal glands were cultured with or without tumor necrosis factor alpha (TNF-α) plus interferon gamma (IFN-γ). Protein secretion was induced by lacritin or carbachol (Cch, positive control). Proteins were detected and identified by immunoblotting and immunocytochemistry. Intracellular Ca(2+) was measured with the fluorophore Calcium-4, and cell damage was determined by LDH leakage into the culture medium. RESULTS In cultured monkey acinar cells, lacritin stimulated tear protein secretion in normal cells without elevating intracellular Ca(2+). In contrast, Cch elevated intracellular Ca(2+) and release of tear proteins. This contrast suggested an alternate, calcium-independent mechanism for lacritin-induced protein secretion. TNF-α plus IFN-γ caused LDH leakage from sensitive human corneal epithelial cells, but even higher doses of TNF-α plus IFN-γ did not cause LDH leakage from monkey acinar cells, suggesting a higher tolerance against these cytokines. In cytokine-treated acinar cells, lacritin stimulated protein secretion as much as that in normal cells. In contrast, Cch-induced elevation of Ca(2+) and release of proteins were depressed by cytokines. CONCLUSIONS Lacritin might be a useful biotechnology-based treatment agent against ocular surface diseases where endogenous lacritin is inadequate.

Patient Selection Criteria for Pilot Studies on Amelioration of Non-Neovascular Age-Related Macular Degeneration

PURPOSES Non-neovascular age-related macular degeneration (AMD) is characterized by accumulation of macular drusen, changes in pigmentation of the retinal pigment epithelium, and geographic atrophy. The purposes of this study were to (1) measure the rate of progression of non-neovascular AMD and (2) from the rate data, to propose patient selection criteria for testing drugs to prevent progression of non-neovascular AMD. METHODS Medical charts were searched for all AMD billing codes, consecutively reviewed, and 51 patients with a median age of 76 years were mined for severity of AMD using a standardized worsening scale from 0 to 6, visual acuity (VA, Snellen), medications or procedures to treat eye diseases, date of eye examinations, age, and sex. Individual eyes, excluding those with cataract, were grouped and compared. RESULTS Using all grades, VA (logMAR) was positively correlated with AMD scores (P < 0.0001, n = 66). The median length of time to progress from AMD grade 3 or 4 to the next grade was 1.0 (n = 14) and 1.7 years (n = 7), respectively. Statistical analyses predicted that drug-treated and nontreated groups, each containing 409 grade 3 and 4 AMD eyes, could detect 50% drug inhibition (P = 0.05) in a 2-year trial. CONCLUSIONS VA measurements and structural AMD grades would be useful markers in clinical trials on non-neovascular AMD. Recruiting only grade 3 and 4 patients may be ideal for time- and cost-efficient pilot drug efficacy studies on moderately progressing non-neovascular AMD.

Selecting Fuchs patients for drug trials involving endothelial cell proliferation.

Purpose Fuchs endothelial corneal dystrophy (FECD) might be managed by drug treatment before becoming severe enough to require surgery. For a clinical trial of such a drug, we hypothesize that selecting an adequate number of patients with FECD with only moderately compromised cell densities will be challenging. Thus, the purpose of the present study was to measure the prevalence of patients with FECD exhibiting moderately decreased corneal cell densities. Methods A retrospective data mining study (cross-sectional study) was performed on patient charts presenting at a large US northwestern academic health center by searching for diagnosis ICD-9 code 371.57 and Fuchs corneal dystrophies, including those with prior cataract surgeries and/or existing glaucoma. Patients with prior corneal transplants were excluded. Noncontact specular photomicroscopic data (Topcon 2000) were obtained from the central region whenever possible, and individual eyes were grouped according to cell density (cells/mm2): severe (<800), moderate (800-1,500), and mild (>1,500). Results The values for 98 eyes from 61 patients with FECD were as follows (mean ± SD): corneal thickness 573 ± 59 μm, cell size 627 ± 336 μm2/cell, coefficient of variation 23 ± 7, and density 1,883 ± 703 cells/mm2. The moderate subgroup with cell density values averaging 1,184 ± 212 (26) comprised 27% of the total FECD patient pool. Conclusions Only approximately 1 out of 4 patients with FECD will show moderately compromised corneal cell densities. A moderate level of damage may be optimal for clinical trials for testing topical drugs on endothelial cell viability. Thus, investigators will need to initially screen a fourfold excess of all patients with FECD.