Purpose:
The meibomian glands of the lid produce a lipid which promotes stability and prevents evaporation of the tear film. The lipids are particularly sensitive to the deleterious effect of lipid peroxidation, witch may result in modifications of the lipid components. Some antioxidant enzyme could be play a protective effect against the lipid peroxidation. To investigate the role of these antioxidant enzymes in the human meibomian glands, mRNA and protein level were analyzed for superoxide dismutase 1 (SOD1), catalase (CAT), and different glutathiones peroxydases GPX1, GPX2, GPX3, GPX4 and GPX5 in human meibomian glands
Methods:
Pieces of human eyelid and conjunctiva were collected during surgery after patient consent according to the tenets of the Declaration of Helsinki. Human meibomian glands were collected after microdissection under the microscope. Reverse transcription-polymerase chain reaction (RT-PCR), enzyme activity and immunochemistry analysis for GPXs were performed on human meibomian glands. Total mRNA and protein were extracted from these tissues, and was analysis to determine the expression patterns of the different GPXs. The global GPX scavenging activity was performed by using tert-butyl hydroperoxide (t-BOOH, 200µM) as substrates. NADPH oxidation was monitored at 340nm
Results:
Expression of Superoxyde dismutase (SOD1), catalase (CAT) and glutathion peroxydase family (GPXs) analyzed by RT-PCR was found in both meibomian gland and conjunctiva. Significant differences in mRNA expression were seen between the different GPXs. GPX1, GPX2 and GPX4 seem highly expressed in both tissues. Moreover, the global GPX scavenging activity analysis shows an antioxidant enzyme activity in both tissues. Immunofluorescence analysis confirmed the presence of GPXs in the meibomian glands
Conclusions:
These data provide evidence for an important role of the antioxidant enzyme activities in meibomain gland. GPXs may be involved in the regulation of meibomian gland function. Thus, this would indicate an important role for the GPX in maintaining the tear film lipid layer and, the health of the ocular surface
Keywords: antioxidants • enzymes/enzyme inhibitors • lipids