Valosin-containing protein is a novel autoantigen in patients with glaucoma.

Objective: The purpose of this study was to identify novel autoantigens that react with specific serum autoantibodies in patients with glaucoma.

Methods: Sera from patients with glaucoma (n = 80) and healthy subjects without a known pathology (n = 20) were investigated by immunoblot performed with bovine optic nerve lysates and resolved by one- and two-dimensional electrophoresis. Proteins in the immunoreactive spots were selected and identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) data analysis. All the sera from subjects were assayed using enzyme-linked immunosorbent assay to identify autoantibodies.

Results: We selected two prominent bands with molecular weights of 100 and 220 kDa by 8% sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis, and these two bands were only found in the glaucoma patients. Using one-dimensional electrophoresis and LC-MS/MS analyses, we identified these proteins to be valosin-containing protein (VCP) and fodrin, respectively, and using two-dimensional electrophoresis and LC-MS/MS analyses, VCP was identified to be a common target antigen. In patients with primary open angle glaucoma and normal tension glaucoma, the frequency of autoantibodies to recombinant human VCP was 42.0 and 23.3%, respectively (p < 0.002). In the enzyme-linked immunosorbent assay tests, autoantibody titers to recombinant human VCP were significantly higher than that in healthy controls (p < 0.025).

Conclusions: VCP represents a potential candidate target for autoantibodies on the optic nerve in patients with glaucoma.