Human lens epithelial cell damage and stimulation of their secretion of chemical mediators by benzalkonium chloride rather than latanoprost and timolol

Objective: To investigate the effects of latanoprost, timolol,maleate, and benzalkonium chloride on cell damage and induction of the secretion of chemical mediators of stress and wound healing by human lens epithelial cells in culture. Methods: Cells from a human lens epithelial cell line (SRA01/04) were cultured in Dulbecco minimum essential medium supplemented with 5% fetal bovine serum. The amounts of latanoprost (50 mug/mL), timolol maleate (5 mg/mL), or benzalkonium chloride (200 mug/mL) used in eyedrops, and x10 to x1000 dilutions thereof, were added to the medium. After 7 days' culture, cell morphological changes were assessed using phase-contrast microscopy, and cell-free culture supernatants were collected for prostaglandin E-2 (PGE(2)), interleukin 1alpha (IL-1alpha), and interleukin 6 (IL-6) iodine I 125 radioimmunoassay, enzyme-linked immunosorbent assay, and chemiluminescent enzyme immunoassay, respectively. Results: All cells that were cultured with the concentrations of latanoprost, timolol, or benzalkonium chloride used in eyedrops detached from the culture dish and died within 3 days. At a x10 dilution of latanoprost or timolol or a x100 dilution of benzalkonium chloride, no proliferation or elongation of the cells was observed. Secretions of PGE(2), IL-1alpha., and IL-6 at x10 dilutions of latanoprost or timolol were 3 to 77 times higher than in controls, whereas they were 190 to 305 times higher at a x180 dilution of benzalkonium chloride. The amounts of these soluble mediators in culture supernatants depended on the dose of latanoprost, timolol, or benzalkonium chloride added. Conclusion: Our results indicate that benzalkonium chloride, used as the preservative in eyedrops containing latanoprost or timolol, is the agent most damaging to lens epithelial cells and most strongly stimulates the expression of soluble chemical mediators in these cells.