Abstract
Purpose: :
To compare the effects of benzalkonium chloride (BAK)-preserved and unpreserved antiallergic eye drops on the human 3D reconstituted corneal epithelial model (HCE).
Methods: :
The HCE were treated for 24h followed or not by a 24-h post-incubation recovery period with phosphate-buffered saline (PBS), 0.01% BAK, unpreserved ketotifen formulation, unpreserved NAAGA commercial solution, and BAK-preserved commercial formulations of ketotifen and epinastine. The cellular viability was evaluated using the MTT test at 24h and 24h+24h. At 24h, the number of CD54- and Ki67- immunopositive cells as well as the number of apoptotic TUNEL-positive cells was evaluated on frozen sections. The expression of tight-junction associated proteins occludin was also assessed using fluorescence confocal microscopy on flat-mounted epithelia.
Results: :
The MTT and the TUNEL tests revealed a significant decrease of cell viability and an increased apoptosis in the superficial layers of the HCE treated with the BAK-containing formulations only. The expression of CD54, Ki67 in the basal layers was also increased in this group. A dose-dependent disorganization of occludin distribution in the epithelium treated with BAK- containing solutions was also observed. Unpreserved solutions induced effects comparable to the control.
Conclusions: :
BAK-preserved solutions decreased cell viability and induced apoptosis. 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 barrier function.
Keywords: cornea: epithelium • ocular irritancy/toxicity testing • apoptosis/cell death