Identification of Retinal Autoantigens in Behcet’s Disease With Uveitis by Proteomic Approach

Abstract

Purpose: : Immune responses to retinal antigens are considerable to be one of the pathogenic mechanisms in Behcet’s disease (BD) patients with ocular involvement. In this study, we attempted to identify retinal autoantigens in BD with uveitis using comprehensive analysis of autoantigens and to define the total profile of autoantigens in each BD patient.

Methods: : Retinal extracts from C57BL/6 mice were separated by 2–dimensional electrophoresis (2DE), and 2DE Western blotting (WB) was performed to detect candidates for autoantigens using serum samples from 13 BD patients with uveitis and from 15 healthy donors. By comparing the two groups, protein spots observed in more than 3 serum samples from BD patients and not to more than one samples from healthy controls were selected and subjected to identification by mass spectrometry and protein data base research. Antigenicity of the identified proteins was confirmed by WB and ELISA using a recombinant protein.

Results: : Eight proteins were isolated and three of them were identified. Two of the identified proteins were S–arrestin and alpha–enolase, which have been reported as candidates of autoantigen in BD. The other was selenium–binding protein (SBP), which reacted with 16% (4/25) of the tested serum samples from BD patients in ELISA using a recombinant human protein. None of the healthy controls (0/26) and patients with proliferative diabetic retinopathy (0/20) and 5% (1/20) of patients with Vogt–Koyanagi–Harada disease were positive for autoantibodies to SBP in ELISA.

Conclusions: : Besides S–arrestin and alpha–enolase, SBP was newly identified as one of the autoantigens in BD patients with uveitis. The proteomic approach is effective for the screening of autoantigens in systemic autoimmune disease.

Keywords: proteomics • uveitis-clinical/animal model • autoimmune disease