Antioxidant enzyme mRNA expression in conjunctival epithelium of healthy human subjects.

OBJECTIVE

To determine the profile, relative quantitation, and correlation of gene expression of the antioxidant enzymes copper-zinc superoxide dismutase (CuZn-SOD), Mn-superoxide dismutase (Mn-SOD), extracellular superoxide dismutase (EC-SOD), catalase (CAT), glutathione synthetase (GSS), and glutathione reductase (GSR) in conjunctival samples from healthy subjects.

DESIGN

Descriptive study.

PARTICIPANTS

Sixteen healthy donors (32 eyes) were included in this study.

METHODS

Conventional and real-time polymerase chain reactions (PCR) were performed using total RNA isolated from conjunctival impression cytology taken from bulbar superior conjunctiva from both eyes.

RESULTS

Products amplified by conventional PCR had only 1 band with the expected size for each target gene. Melt-curve analysis of real-time PCR products also identified a single amplified product for each gene. Log-transformed antioxidant enzyme mRNA expression levels, relative to glyceraldehyde-3-phosphate dehydrogenase expression (mean ± standard error of the mean [SEM]), were CuZn-SOD, 1.52 ± 0.13; Mn-SOD, 1.72 ± 0.08; EC-SOD, 0.35 ± 0.08; GSS, 2.43 ± 0.20; GSR, 2.52 ± 0.16; and CAT, 0.90 ± 0.08. The mRNA levels for CuZn-SOD were strongly correlated with GSS, GSR, Mn-SOD, and EC-SOD. Similarly, the levels of mRNA of GSS and GSR were strongly correlated with each other and with Mn-SOD and EC-SOD.

CONCLUSIONS

Normal human conjunctiva expresses the antioxidant enzymes genes CuZn-SOD, Mn-SOD, EC-SOD, CAT, GSS, and GSR. The relative quantitation of these genes expressed in conjunctivas of normal eyes will allow further comparisons in pathological circumstances. Knowledge of correlated gene expression will provide a better understanding of the antioxidant balance in the ocular surface.