Purpose To compare the effects of benzalkonium chloride (BAC)-preserved and unpreserved antiallergic eye drops on the human 3D-reconstituted corneal epithelial model (3D-HCE). only when treated with BAC-containing formulations and in a BAC concentration-dependent manner. The expression of CD54 and Ki67 in the basal layers was also increased in this group. A concentration-dependent disorganization of occludin distribution in the epithelium treated with BAC-containing solutions was also observed. The unpreserved formulations induced effects comparable to the control. Conclusions BAC-preserved solutions decreased cell viability and induced apoptosis in a concentration-dependent manner. Moreover, they induced CD54 expression, proliferation in the basal layers, and changes in the distribution of occludin, which is consistent with a disorganization of the tight-junctions and suggests the loss of the epithelial GSK1059615 barrier function. On GSK1059615 the contrary, the unpreserved solutions did not impair cell structures and viability, suggesting a better tolerance for the ocular surface. As allergic patients often exhibit impaired and inflammatory ocular surface, BAC-free compounds should be the first choice when treating allergic conjunctivitis. Introduction To limit and counteract the clinical manifestations of allergic diseases, antiallergic compounds can be used. One of these molecules, ketotifen fumarate, has demonstrated both H1-receptor antagonism and mast cell stabilizing properties while inhibiting chemotaxis and eosinophil activation [1,2]. Moreover, ketotifen fumarate was shown to be well tolerated and effective in reducing the signs and symptoms of allergic conjunctivitis [3-6]. Allergic conjunctivitis, however, has often a tendency to become chronic, due to repeated allergic challenge or progressive impairment of the tear film and ocular surface [7,8]. As preservatives are usually used to prevent multidose eyedrop microbial contamination, their chronic administration may cause further ocular surface changes, at the levels of tear film and conjunctiva. They can induce cytotoxic effects and deleterious reactions when used over long-term periods. Indeed, the mostly used preservative benzalkonium chloride (BAC) was already shown to exhibit toxic and inflammatory effects in clinical, in vivo and in vitro studies [9-20]. Chronic use of BAC in eye drops is known to be responsible for apoptosis and oxidative stress on conjunctival GSK1059615 cells, and to induce conjunctival inflammation that has demonstrated potentially harmful effects on glaucoma outcome, e.g., on glaucoma surgery efficacy [17,21-25]. In this context, the implementation of very sensitive tools to predict eye tolerance is critical for ophthalmologists, GSK1059615 who may be faced with long-term induced toxicity of substances used at low concentration in ophthalmic preparations. Supplied by SkinEthic? Laboratories (Nice, France), the reconstructed three-dimensional (3D) model of human corneal cells (3D-HCE) is an appropriate model for pre-screening or investigating the undesirable effects of ophthalmic drugs. It constitutes an interesting alternative to animal testing that is time-consuming and often invasive and may lack suited sensitive tools able to detect subclinical reactions [26-28]. Multi-endpoint analyses using adapted and improved techniques on such 3D-models have already proved efficacy for the assessment of BAC toxicity [28] and eyedrop tolerance [27]. The objective of this study was to investigate a large range of commonly used antiallergic eye drops in this 3D-HCE GSK1059615 system and compare the tissue changes after treatment with BAC-preserved commercial formulations of ketotifen, olopatadine, epinastine or levocabastine, and unpreserved commercial formulations of ketotifen, N Acetyl-Aspartyl Glutamic Acid (NAAGA), or cromoglycate. Particularly, our purpose was to determine the involvement of BAC in epithelial cell damage induced after treatment with BAC-preserved and unpreserved antiallergic eyedrops. Methods Tissue model and antiallergic solution treatments The 3D-HCE Mouse monoclonal antibody to Protein Phosphatase 3 alpha model (SkinEthic? Laboratories, Nice, France) consists of immortalized HCE cells grown vertically on a 0.5 cm2 insert permeable polycarbonate filter. All.