gms | German Medical Science

Wearing contact lenses not infrequently occasions morphological changes of the epithelia cells at the conjunctival ocular surface, such as condensation of the chromatin ("snake-like-chromatin") or a reduction of the density of goblet cells. Based on preliminary examinations of young and elderly probands with healthy eyes in whom age dependence of the expression of apoptosis-associated genes was found, the aim of the present study was to find possible impacts on the gene expression in the superficial epithelium of the conjunctiva caused by wearing soft contact lenses.

The expression of apoptosis markers was studied in 21 wearers of soft contact lenses, group A, 24 years average age). The results were referenced to those obtained from 26 subjects with healthy eyes (groups B, 21 years average age) and 26 elderly subjects (group C,: 69 years average age). Epithelial cells were collected from bulbar conjunctiva using modifications of the impression cytology. RNA was isolated from the cytologic impression specimens using a kit. Eluted RNA was used for cDNA-synthesis employing SuperScriptTM II reverse transcriptase according to standard protocol. Different apoptosis genes were detected by PCR amplification using CytoXpressTM Multiplex-PCR with primers for apoptosis-associated genes APAF-1, Caspases (Casp) 3, 5, 8, and 9; Bad, Bax, Bcl-2, Bim, Bag-1, c-myc and p53. Statistical significance was tested using the Chi-square test after Pearson.

Using RT-PCR, the following expression pattern was obtained for group A contact wearers: APAF-1: 0%; Bcl-2: 67%, Bim: 0%, Bag-1 52%, p53 14%, Casp-3: 48%, Casp-5: 29%, Casp-8: 48%, Casp-9: 38%, BAX: 43%, and BAD: 95%. Significant differences in the expression of apoptosis-associated genes were found by a comparison of the contact lens wearers with the young subjects for Casp-3 (48%-4%; p=0,001), Casp-5 (29%-71%; p=0,007), and Bax (57%-92%; p=0,013). In contrast to this, significant differences in the expression pattern between contact lens wearers and elderly subjects were only found for Bag-1 (50%-100%, p=0.0001).

Wearing contact lenses does not only cause the known process of metaplasia in the conjunctival epithelium, it is also responsible for changes in the expression of apoptosis-associated genes. Agreements in the expression pattern were more frequent for the group of elderly subjects and the contact lens wearer group. As anti-apoptotic Bcl-2 was expressed more frequently by contact lens wearers, it is suggested that epithelial cells require apoptotic protection.