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Abstract #8225 Published in IGR 4-3
Human trabecular cells and apoptosis: in vitro evaluation of the effect of betaxolol with or without preservative
Hamard P; Debbash C; Blondin C; Brignole F; Loison-Dayma K; Warnet JM; Baudouin CJournal Français d'Ophtalmologie 2002; 25: 777-784
PURPOSE: Trabecular meshwork, which is involved in aqueous outflow resistance, is deeply modified in glaucoma patients, with a decrease in the trabecular cell number. Trabecular toxicity of antiglaucoma medications cannot be excluded. On a human cultured trabecular cell line, the authors investigated the potential proapoptotic effect of a beta-blocker with or without the preservative, benzalkonium chloride (0.01% BAC), by flow cytometry and confocal microscopy. MATERIAL AND METHODS: A human immortalized trabecular cell line (HTM-5) obtained from a normal donor was cultured under normal conditions. Preserved 0.25% betaxolol suspension (betaxolol BAC +), unpreserved 0.25% betaxolol suspension, and 0.01% BAC were, respectively, added to the cultured medium in a 1/10 or 1/100 dilution for 15 minutes. After a 24-hour recovery period in normal culture conditions, cell size and the expression of an apoptotic marker, Apo 2.7, were evaluated by flow cytometry and confocal microscopy. Untreated trabecular cells were used as control cells. RESULTS: Preserved and unpreserved betaxolol in a 1/10 dilution induced a significant decrease in trabecular cells size compared to controls. However, this decrease in cell size was less pronounced than that induced by BAC at the same dilution. Similar results were obtained with betaxolol and BAC in a 1/100 dilution. Trabecular cell Apo 2.7 expression was significantly increased after treatment with betaxolol BAC + and BAC- in a 1/10 dilution compared to controls (36.8, 28.1, and 15.4%, respectively, p < 0.005). However, the proapoptotic activity was much less pronounced than that induced by BAC- at the same dilution (96.9%, p < 104). Unpreserved betaxolol in a 1/100 dilution had no apoptotic activity on trabecular cells. Trabecular cell Apo 2.7 expression slightly increased with betaxolol BAC + at a 1/100 dilution (24.9%, p = 0.04), while it was greatly increased with BAC at the same dilution (39.9%, p < 104). CONCLUSIONS: In the authors' model, unpreserved betaxolol at a low concentration displayed no proapoptotic activity on trabecular cells. On the other hand, preserved betaxolol displayed moderate proapoptotic activity by triggering cell death of around 25% of cells. Trabecular cell toxicity appeared to be mainly due to the preservative BAC. Taken together, these results demonstrated that the strong apoptotic activity of BAC was greatly reduced within the preserved eye drops, probably through the interaction of BAC with the active compound.LA: French
P. Hamard, MD, Services d'Ophtalmologie 3, CHNO des Quinze-Vingts, 28 rue de Charenton, 75012 Paris, France. pascale-hamard@quinze-vingts.fr
Classification:
11.3.4 Betablocker (Part of: 11 Medical treatment > 11.3 Adrenergic drugs)
