N. Yamakawa

Supplementation of CD4+CD25+ regulatory T cells suppresses experimental autoimmune uveoretinitis

Aims: To investigate whether supplementation of natural CD4+CD25+ regulatory T cells ameliorates mouse experimental autoimmune uveoretinitis (EAU) induced by CD4+ T cell-dependent interphotoreceptor retinoid-binding protein (IRBP). Methods: C57BL/6 mice were immunised with human interphotoreceptor retinoid-binding protein peptide 1–20 (IRBP1–20), and IRBP1–20-sensitised T cells were obtained. CD4+CD25+ T cells derived from naive mice were cocultured with IRBP1–20-sensitised T cells, and their proliferation responses and cytokine production were measured. In addition, CD4+CD25+ T cells were transferred intravenously into mice 7 or 15 days after immunisation with IRBP1–20, and the severity of EAU and T cell proliferation responses were evaluated. Results: CD4+CD25+ regulatory T cells effectively inhibited both the proliferation of, and interleukin (IL)2, IL5 and interferon (IFN)γ production by, IRBP1–20-sensitised T cells. Adoptive transfer of CD4+CD25+ regulatory T cells to IRBP1–20-immunised mice conferred considerable protection from EAU development and inhibition of T cell proliferation responses to IRBP1–20. Conclusion: These findings show that natural CD4+CD25+ regulatory T cells possess the ability to inhibit activation of IRBP-reactive T cells that have been already sensitised in vivo, and adoptive transfer of these cells ameliorates EAU even in the effector phase. Supplementation of natural CD4+CD25+ regulatory T cells may have therapeutic potential for effective treatment of uveitis.

Peritoneal Exudate Cells Treated with Calcitonin Gene-Related Peptide Suppress Murine Experimental Autoimmune Uveoretinitis via IL-10

Immunization with retinal Ag induces experimental autoimmune uveoretinitis (EAU) in mice. We investigated the suppression of murine EAU by peritoneal exudate cells (PEC) cultured with calcitonin gene-related peptide (CGRP). PEC derived from mice were treated with CGRP and residues 1–20 of human interphotoreceptor retinoid-binding protein (hIRBP 1–20). The hIRBP 1–20-immunized mice were injected i.v. with PEC treated with CGRP and hIRBP 1–20. After immunization, Ag-specific delayed hypersensitivity (DH) was measured and EAU was assessed histopathologically. Both EAU- and Ag-specific DH were suppressed by injection of PEC treated with CGRP (100 ng/ml) and hIRBP 1–20. However, hIRBP 1–20-mediated EAU was not suppressed by injection of PEC treated with CGRP and BSA. Both EAU- and Ag-specific DH were not suppressed by injection of PEC treated with CGRP and hIRBP 1–20 into splenectomized mice. In mice adoptively transferred spleen cells from hIRBP 1–20-immunized mice, EAU was also suppressed by injection of CGRP-treated PEC. EAU was markedly inhibited in hIRBP 1–20-immunized mice adoptively transferred T cells obtained from mice injected with hIRBP 1–20-pulsed, CGRP-treated PEC. Furthermore, EAU- and Ag-specific DH were not suppressed by injection of PEC treated with CGRP and hIRBP 1–20 when the recipient mice were given anti-IL-10 Ab i.p., or when the PEC were derived from IL-10 knockout mice. The present results indicate that PEC treated with CGRP suppress murine EAU in an Ag-specific manner, even in the efferent phase, and IL-10 secreted from PEC might play an important role in the CGRP-mediated suppression of murine EAU.