Comparison of mucin genes expression alterations in conjunctival epithelium induced by high and low water content hydrogel contact lenses.

Abstract

Abstract: : Purpose: To determine whether water content in non ionic hydrogel contact lenses (HCL) may have influence in the alteration of the expression of the 9 reported conjunctival mucin genes after one year of wear. Methods: Sixteen healthy subjects with no history of contact lens wear were selected. Patients were randomized into two groups. Group 1: 8 patients (16 eyes) fitted with low water content (38%) non ionic HCL; group 2: 8 patients (16 eyes) fitted with high water content (66%) non ionic HCL. Conjunctival impression cytology was performed by applying two polyethersulfone filters to the superior bulbar conjunctiva of both eyes before HCL fitting, and at 6 months, 1 year and 15 days after discontinuation of wear. Real time polymerase chain reaction was performed using isolated and retrotranscribed total RNA to quantify the expression of conjunctival mucin genes (MUC1, MUC2, MUC4, MUC5AC, MUC7, MUC13, MUC15, MUC16, and MUC17). Their relative quantity was determined by SYBR^® Green I dye detection. The housekeeping gene GAPDH was used to normalize the amount of expression levels. Chronologic variations were analyzed using Student's test and lineal regression. Results: Only MUC16 expression showed differences between both groups (p<0.05) with higher levels in group 1. Transcripts of MUC1, MUC4, MUC5AC, MUC13, MUC16, and MUC17 increased (p<0.05) after 6 or 12 months of HCL wear. However, the number of transcripts for MUC7 and MUC15 significantly decreased (p < 0.01) after 6 or 12 months of HCL wear. There were not significant changes in the expression of conjunctival mucin genes 15 days after discontinuing HCL wear. Conclusions: Water content did not influence in the changes of the conjunctival mucin genes expression induced by non ionic HCL wear. Reduced levels of MUC7 gene expression may be one of the mechanisms implicated in the increased rate of infection seen in HCL wearers.

Keywords: cornea: tears/tear film/dry eye • cornea: surface mucins • contact lens