Effects of multipurpose contact lens care solutions and their ingredients on membrane-associated mucins of human corneal epithelial cells

Purpose: Membrane-associated mucins play an important role for protecting epithelial cells at the ocular surface from microbial invasion. The purpose of this study was to determine whether multipurpose solutions (MPSs) for contact lens care and their ingredients alter the expression of membrane-associated mucins in human corneal epithelial (HCE-T) cells. Methods: SV40-immortalized HCE-T cells were cultured in Dulbecco's modified Eagle medium/F12 medium with 5% fetal bovine serum to confluence and were then exposed to 10% dilutions of five different MPSs, or to their representative ingredients, 0.1% macrogolglycerol hydroxystearate, 0.1% poloxamer, 0.1% poloxamine, 1 and 5 ppm polyhexamethylene biguanide, or 0.05% and 0.1% boric acid for 24 hr. Quantitative real-time polymerase chain reaction was used to investigate the gene expression of MUC1, MUC4, and MUC16. Immunofluorescence staining of MUC16 protein on the surface of the HCE-T cells exposed to 10% diluted MPSs for 24 hr or undiluted MPSs for 30 min was observed by laser confocal scanning microscopy followed by quantitative image analysis. Results: Three MPSs containing boric acid significantly reduced gene expressions of MUC1 from 20.2% to 56.7% (P<0.01). Gene expressions of MUC4 and MUC16 were also reduced by these MPSs; however, there were no significant differences. Among ingredients, 0.1% boric acid significantly reduced gene expressions of MUC1 and MUC16 by 7.4% and 18.9%, respectively (P<0.01). Immunofluorescence microscopy also demonstrated that in undiluted form, three MPSs containing boric acid significantly reduced the expression of MUC16 protein. Conclusions: The MPSs containing boric acid downregulate membrane-associated mucins as compared with MPSs that do not contain boric acid. There may be some subtle membrane or other interactions between ingredients in lens-care solutions that adversely alter corneal cell mucins.