Staphylococcal enterotoxin B is involved in aggravation and recurrence of murine experimental autoimmune uveoretinitis via Vβ8+CD4+ T cells

Endogenous uveitis is a common cause of visual disability and blindness. The etiology of uveitis remains largely unknown but reasonable etiologic factors include infections. Superantigens are regarded as one of the leading causes of infectious etiology in autoimmune disease. However, the role of superantigens in uveitis remains unclear. In the present study, we investigated the effect of Staphylococcal enterotoxin B (SEB), a member of the superantigens, using an experimental model of autoimmune uveoretinitis (EAU). C57BL/6 mice were immunized with human interphotoreceptor retinoid binding protein (IRBP) peptide, and the severity of EAU disease was scored. Vehicle (PBS) alone or SEB dissolved in PBS was administered by intravenous injection on post-immunization day 10 or on post-immunization day 24. In addition, a systemic immune response study was performed to address the effects of SEB on systemic immunity. EAU was aggravated significantly by the injection of SEB at post-immunization day 10. Furthermore, relapse was induced by the injection of SEB at day 24. On the other hand, SEB injection without IRBP peptide immunization elicited no inflammatory changes in the uvea or retina. Furthermore, SEB enhanced not only the IRBP-specific T-cell proliferative responses but also IFN-γ and IL-17 production. Moreover, the intraocular expression levels of these cytokines was also enhanced by SEB injection. Both anti-CD4 and -Vβ8 Ab administration suppressed disease aggravation and the enhancement of IRBP-specific T-cell responses caused by SEB. These results suggest that SEB is involved significantly in the aggravation or recurrence of endogenous uveitis through activation of autoreactive uveitogenic T cells.