Zaki Nakib

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Dry eye is a multifactorial disease that may be caused by eye drop preservatives. Our aim was to establish an in vitro dry eye model and to evaluate the toxicity of the combination of both desiccation and benzalkonium chloride (BAK) chemical stress. BAK has surfactant and preservative properties in eyedrops and its toxicity to the ocular surface is well known. Using a conjunctival cell line, we investigated cell viability, apoptosis and oxidative stress with cold light- and flow- cytometry (FCM) and the expression of the chemokine CCL2 and its receptor CCR2 with FCM and immunofluorescence. The results showed that desiccation induces apoptosis , loss of viability without oxidative stress and membrane CCL2/CCR2 overexpression. The combination of the two stresses revealed a toxicityincrease and a potentiating toxic effect through a drastic decrease in cell viability, a significant increase of apoptosis, oxidative stress and of the expression of the inflammatory chemokine CCL2 and CCR2. This preliminary study confirms the importance of this potentiating toxic effect between dessication and preservative and could offer a new model to investigate and better understand the vicious circle of hyperosmolarity and inflammation observed in dry eye patients.

Outras informações:
Long-term treatment of glaucoma with antiglaucomatous eye drops is known to induce toxic side effects on the ocular surface as allergy, dry eye and inflammation. Numerous studies demonstrated that the preservative, benzalkonium chloride (BAC), commonly used in eyes drops is the main actor of this toxicity that may affect patient compliance to treatment. Thus, laboratories try to develop new formulations in order to minimize side effects. The purpose of this work was to evaluate in vitro on conjunctival epithelial cells, the toxicological profile of three eyes drops with different BAC concentration and with a new preservative promising to be less toxic than BAC. We used the microtitration in fluorescence assay on live cells to assess cytotoxicity : cell viability using neutral red and Alamar blue assays, apoptosis (Hoechst and Yopro-1 tests) and oxidative stress (Hydroethidin and dichlorofluorescein diacetate tests) generated by these products. The toxicological profiles of these products demonstrated once more the concentration-dependent cytotoxicity of BAC and confirmed the absence of toxicity with the new preservative, justifying the interest in developing the new anti glaucomatous formulation associated with this new preservative.