Identification of tribbles homolog 2 as an autoantigen in autoimmune uveitis by phage display

Autoimmune uveitis is a group of ocular inflammatory disorders with unknown causes. As in other autoimmune diseases, identification of autoantigens from uveitis patients would markedly improve our understanding of the disease mechanism. Here, we report that a candidate autoantigen was identified by phage display in an unbiased fashion. A bacteriophage T7 display cDNA library was generated from human eye and characterized. Patient-specific phages were enriched by four rounds of phage display with purified patient IgG. Enriched phages demonstrated a 20-fold increase in binding specificity to the patient IgG compared with control IgG. Two clonal phages with particularly high relative binding specificities were isolated and characterized. The encoded genes, tribbles homolog 2 (TRB2) and an unknown protein, had 170- and 42-fold increases in their binding specificities to the patient IgG, respectively. The patient-specific immunoreactivities were further confirmed by Western blotting. Anti-TRB2 antibody activities were detected in several uveitis patients but not in control subjects, suggesting that TRB2 is a uveitis-associated candidate autoantigen. These results demonstrate that autoantigens can be identified by phage display using uveitis patient serum.