Abstract
Purpose: :
In previous studies alterations in IgG autoantibody patterns of glaucoma patients have been shown. Hitherto, IgM antibody patterns have not been analyzed nor compared to IgG antibody reactivities either. The aim of this study was to perform an intraindividual comparison of the IgG and IgM antibody reactivities in patients with primary open-angle glaucoma (POAG) and healthy subjects (CO). For this purpose we used an advanced protein microarray approach.
Methods: :
Sera of age- and gender-matched POAG-patients (n=19) and CO subjects (n=19) were used for antibody analysis. Protein microarrays were prepared by spotting 56 ocular antigens onto nitrocellulose-coated slides. These were incubated with diluted sera (1:250) and antibody-antigen-reactions were visualized with fluorescence labeled anti-IgG and IgM secondary antibodies. Emitted fluorescence signals were digitized and spot intensities were compared using diverse statistical techniques such as multivariate analysis of discriminance and artificial neural networks.
Results: :
Overall we could detect complex IgG and IgM autoantibody patterns. 16 autoantibodies, e.g. anti-Caspase 3 or anti-β-S-Crystallin, were found to reveal significant differences in IgG autoantibody patterns of POAG subjects in comparison to the CO group (each with P≤0.0008). In IgM immunoreactivity patterns 19 autoantibodies showed statistically significant differences between the groups (e.g. anti-Spectrin or anti-α-1-Antitrypsin; P≤0.0001). Several of the shifted immunoreactivities were found to be diminished in POAG patients. 68% of the IgG autoantibody reactivities correlated with differences in IgM patterns. Calculated IgG/IgM ratios revealed no group differences. Using a biomarker panel of 10 IgG or IgM antibodies we could differentiate between glaucoma and healthy subjects with a sensitivity and specificity of >87%.
Conclusions: :
For the first time IgG and IgM autoantibody reactivities in glaucoma patients were compared intraindividually. We could show that the alterations of IgG patterns strongly correlate with IgM reactivities, indicating that ongoing autoimmune processes are more complex than suggested by previously detected changes in IgG autoantibody patterns. Down-regulations of antibody reactivities in sera provide further signs for a loss of natural, potentially protective autoimmunity. These findings could lead to new therapeutic and diagnostic tools.
Keywords: immunomodulation/immunoregulation • proteomics • discrimination