Takaaki Hattori

Suppression of experimental autoimmune uveoretinitis by inducing differentiation of regulatory T cells via activation of aryl hydrocarbon receptor.

Purpose. Aryl hydrocarbon receptor (AHR) has been identified as a regulator of CD25(+)CD4(+) regulatory T-cell (T(reg)) and Th17 cell differentiation in mice, and activation of AHR by its ligand 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces functional T(reg) cells. In this study, the authors examined whether the AHR-mediated effect of TCDD suppresses mouse experimental autoimmune uveitis (EAU) by inducing T(reg) cell differentiation. Methods. C57BL/6 mice were injected with TCDD 1 day before immunization with human interphotoreceptor retinoid-binding protein peptide 1-20 (hIRBP-p), and the severity of EAU was assessed clinically and histopathologically. Immunologic responses of draining lymph node cells and splenocytes to hIRBP-p and anti-CD3 monoclonal antibody (mAb) were assessed by T-cell proliferation and cytokine production. In addition, differentiation of Foxp3(+) T cells and their immunosuppressive roles in TCDD-injected mice were evaluated. Results. TCDD injection increased Foxp3(+) T cells in the lymph nodes and in the spleen. Development of EAU was completely suppressed by TCDD injection, and suppression was abolished by treatment with anti-CD25 mAb before TCDD injection. Both lymphocytes and splenocytes obtained from TCDD-injected mice immunized with hIRBP-p failed to produce IFN-gamma and IL-17 on stimulation with hIRBP-p, and the failure of IL-17 production was observed even when stimulated with anti-CD3 mAb. However, this protocol did not interfere with IL-10 production and T-cell proliferation response when assessed on stimulation with anti-CD3 mAb. Conclusions. Activation of AHR by TCDD markedly suppressed autoimmune uveoretinitis through mechanisms that expand CD25(+)Foxp3(+) T(reg) cells and interfere with the activation of Th1 and Th17 cells.

Dependence of Corneal Stem/Progenitor Cells on Ocular Surface Innervation

PURPOSE Neurotrophic keratopathy (NK) is a corneal degeneration associated with corneal nerve dysfunction. It can cause corneal epithelial defects, stromal thinning, and perforation. However, it is not clear if and to which extent epithelial stem cells are affected in NK. The purpose of this study was to identify the relationship between corneolimbal epithelial progenitor/stem cells and sensory nerves using a denervated mouse model of NK. METHODS NK was induced in mice by electrocoagulation of the ophthalmic branch of the trigeminal nerve. The absence of corneal nerves was confirmed with β-III tubulin immunostaining and blink reflex test after 7 days. ATP-binding cassette subfamily G member 2 (ABCG2), p63, and hairy enhancer of split 1 (Hes1) were chosen as corneolimbal stem/progenitor cell markers and assessed in denervated mice versus controls by immunofluorescent microscopy and real-time PCR. In addition, corneolimbal stem/progenitor cells were detected as side population cells using flow cytometry, and colony-forming efficiency assay was performed to assess their function. RESULTS ABCG2, p63, and Hes1 immunostaining were significantly decreased in denervated eyes after 7 days. Similarly, the expression levels of ABCG2, p63, K15, Hes1, and N-cadherin transcripts were also significantly decreased in denervated eyes. Stem/progenitor cells measured as side population from NK mice were decreased by approximately 75% compared with normals. In addition, the authors found a significant (P = 0.038) reduction in colony-forming efficiency of stem/progenitor cells harvested from denervated eyes. CONCLUSIONS Corneolimbal stem/progenitor cells are significantly reduced after depletion of sensory nerves. The data suggest a critical role of innervation in maintaining stem cells and/or the stem cell niche.

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.

Expression of toll-like receptor 4 contributes to corneal inflammation in experimental dry eye disease.

Purpose. To investigate the corneal expression of toll-like receptor (TLR) 4 and determine its contribution to the immunopathogenesis of dry eye disease (DED). Methods. Seven to 8-week-old female C57BL/6 mice were housed in a controlled environment chamber and administered scopolamine to induce experimental DED. Mice received intravenous TLR4 inhibitor (Eritoran) to block systemic TLR4-mediated activity. The expression of TLR4 by the corneal epithelium and stroma was evaluated using real-time polymerase chain reaction and flow cytometry. Corneal fluorescein staining (CFS) was performed to evaluate clinical disease severity. The corneal expression of proinflammatory cytokines (IL-1β, IL-6, TNF, and CCL2), corneal infiltration of CD11b(+) antigen-presenting cells, and lymph node frequency of mature MHC-II(hi) CD11b(+) cells were assessed. Results. The epithelial cells of normal corneas expressed TLR4 intracellularly; however, DED significantly increased the cell surface expression of TLR4. Similarly, flow cytometric analysis of stromal cells revealed a significant increase in the expression of TLR4 proteins by DED-induced corneas as compared with normal corneas. DED increased the mRNA expression of TLR4 in corneal stromal cells, but not epithelial cells. TLR4 inhibition decreased the severity of CFS and significantly reduced the mRNA expression of IL-1β, IL-6, and TNF. Furthermore, TLR4 inhibition significantly reduced the corneal infiltration of CD11b(+) cells and the lymph node frequency of MHC-II(hi) CD11b(+) cells. Conclusions. These results suggest that DED increases the corneal expression of TLR4 and that TLR4 participates in the inflammatory response to ocular surface desiccating stress.

Vascular endothelial growth factor-C promotes alloimmunity by amplifying antigen-presenting cell maturation and lymphangiogenesis.

PURPOSE To investigate the role of anti-vascular endothelial growth factor (VEGF)-C therapy in corneal graft survival and concomitant suppression of hem- and lymph-angiogenesis. METHODS Corneal suture model in BALB/c mice was placed and immunohistochemical staining was performed with CD31/PECAM-1 and LYVE-1 to quantify the level of blood and lymphatic vessels. Corneal transplants were done in BALB/c mice from C57BL/6 mice donors; grafts were subsequently scored for opacity. VEGF-C was blocked in the angiogenesis and transplant model using neutralizing monoclonal anti-VEGF-C (VGX-100) by intraperitoneal injection. To determine the function of VEGF-C in maturation of antigen-presenting cells (APCs), bone marrow-derived dendritic cells were generated and matured in the presence or absence of VEGF-C. RESULTS VEGF-C expression was demonstrated to be markedly upregulated in corneal graft rejection. VEGF-C blockade, through administration of a VEGF-C blocking monoclonal antibody, suppresses corneal angiogenic responses, inhibits trafficking and maturation of APCs, and significantly improves allotransplant survival. CONCLUSIONS These data suggest VEGF-C as a potentially important target in corneal transplant pharmacotherapy and immunobiology.

Immune Responses to Interphotoreceptor Retinoid-Binding Protein and S-Antigen in Behçet's Patients With Uveitis

PURPOSE Immune responses to retina-specific autoantigens, including S antigen (S-Ag) and interphotoreceptor retinoid binding protein (IRBP), have been suggested to be involved in the pathogenesis of human uveitis, including Behçets disease (BD). In this study, the authors examined whether immune responses to IRBP and S-Ag in BD patients can be characterized by cytokine production profiles. METHODS Peripheral blood mononuclear cells (PBMCs) were collected from BD patients with uveitis and healthy controls, and each sample was cultured with IRBP, S-Ag, or purified protein derivative (PPD). At the end of culture, IL-2, IL-4, IL-6, IL-10, IL-17, IFN-gamma, and TNF-alpha concentrations in supernatants were measured. RESULTS PBMCs from BD patients and healthy controls produced IL-6, IL-10, IL-17, IFN-gamma, and TNF-alpha on stimulation with IRBP or S-Ag, as well as PPD stimulation, immunity against which was acquired by Bacille Calmette-Guérin immunization. IL-17 and IFN-gamma production was significantly higher when PBMCs were stimulated with IRBP than with S-Ag, whereas the reverse was observed for IL-6 production. IRBP-stimulated IL-6, IFN-gamma, and IL-17 production was higher in BD patients than in healthy controls, though IL-10 production was not different between them. In particular, IRBP-stimulated IFN-gamma production was significantly higher in BD patients with active uveitis than in BD patients with uveitis in remission. CONCLUSIONS Immune responses to both IRBP and S-Ag were observed even in PBMCs of healthy controls. However, the present results suggested that retinal autoantigen-stimulated IL-6, IL-17, and especially IFN-gamma production would be involved in the development of uveitis in BD.

The role of the ICOS/B7RP-1 T cell costimulatory pathway in murine experimental autoimmune uveoretinitis

ICOS/B7RP‐1 is a new member of the CD28/B7 family of costimulatory molecules and plays differential roles in autoimmune diseases. In this study, we examined the role of ICOS/B7RP‐1 pathway in the pathogenesis of mouse experimental autoimmune uveoretinitis (EAU), an animal model of human autoimmune uveitis. ICOS expression was found on infiltrating CD4+ T cells in the region of the retina in EAU‐induced mice. The anti‐B7RP‐1 monoclonal antibody (mAb)‐treated or ICOS‐deficient mice showed a substantial reduction of disease scores. Blockade of ICOS/B7RP‐1 interaction during the effector phase ameliorated the disease, whereas its blockade during the induction phase exhibited no significant effect. Moreover, administration of anti‐B7RP‐1 mAb effectively ameliorated the disease induced by adoptive transfer of pathogenic T cells. The anti‐B7RP‐1 mAb treatment inhibited the expansion and/or effector function of pathogenic T cells, given that proliferative response and IFN‐γ production by lymph node cells were reduced upon restimulation with the antigen peptide in vitro. These results suggest that the ICOS/B7RP‐1 interaction plays a critical role in the pathogenesis of uveitis. We also indicated that ICOS‐mediated costimulation plays differential roles in EAU and experimental autoimmune encephalomyelitis, which is also a Th1 disease induced in the same manner as EAU.

Suppression of Experimental Autoimmune Uveoretinitis by Regulatory Dendritic Cells in Mice

OBJECTIVE To examine the effects of bone marrow-derived regulatory dendritic cells (DCs) with potent immunoregulatory properties on the development of experimental autoimmune uveoretinitis (EAU). METHODS Bone marrow cells obtained from C57BL/6 mice were treated with granulocyte-macrophage colony-stimulating factor, transforming growth factor beta, and interleukin (IL) 10 and stimulated with lipopolysaccharide to produce mature and regulatory DCs. Expression of major histocompatibility complex and costimulatory molecules was analyzed by flow cytometry. Then EAU was induced by immunization with human interphotoreceptor retinoid-binding protein (hIRBP) peptide 1-20, followed by intravenous injection of hIRBP peptide-pulsed regulatory DCs. Control mice received transforming growth factor beta and IL-10 nontreated mature DC or phosphate-buffered saline. We evaluated EAU clinically and histopathologically. Immunologic responses to hIRBP peptide were assessed by delayed-type hypersensitivity and T-cell proliferation and cytokine production. RESULTS Regulatory DCs expressed comparable levels of major histocompatibility complex class II molecules but reduced levels of CD80, CD86, and CD40 compared with mature DCs. Delayed-type hypersensitivity to hIRBP peptide and the development of EAU were markedly suppressed in mice receiving regulatory DCs compared with control mice. Lymph node cells from regulatory DC-treated mice showed significantly reduced hIRBP-specific T-cell proliferation and interferon gamma production but increased IL-10 production. CONCLUSION Administration of regulatory DCs potentially inhibited the development of EAU. CLINICAL RELEVANCE Application of regulatory DCs may be a novel candidate for immunotherapy for human endogenous uveitis.

Circulating neutrophils in Behçet disease is resistant for apoptotic cell death in the remission phase of uveitis

BackgroundBehçet disease (BD) is manifested by recurrent acute iridocyclitis with hypopyon in the active phase, which regresses spontaneously. Hypopyon consists of inflammatory cells infiltrating the eye, with polymorphonuclear cells (PMNs) as the main component. The present study was conducted to investigate the apoptosis property of PMNs in BD patients with uveitis.MethodsPMNs were purified from peripheral blood cells of BD patients with uveitis in the active or remission phase and were cultured for 12 hours. In some cultures, lipopolysaccharide (LPS), antagonistic anti-TNFα antibody, agonistic anti-Fas antibody, or Fas:Fc fusion protein was added. At the end of cultures, apoptotic cells were evaluated by Annexin V expression using flow cytometry.ResultsSpontaneous apoptosis of PMNs showed lower levels in the remission phase of BD-related uveitis compared with the active phase or healthy controls. The lower level of PMN apoptosis in the remission phase of uveitis in BD remained even by stimulation with LPS, anti-TNFα antibody, or Fas:Fc fusion protein, which was abolished in the presence of agonistic anti-Fas antibody.ConclusionsIn BD patients, the apoptosis of PMNs was reduced in the remission phase of uveitis and restored in the active phase, which arose from the apoptotic cell death in part via Fas-Fas ligand interaction.

Blockade of the OX40 ligand prolongs corneal allograft survival

Although corneal transplantation is one of the most common tissue transplantations and is known to have a high graft acceptance rate, occasional corneal graft rejection remains a cause of blindness. OX40, a member of the TNF receptor superfamily, is expressed on activated T cells, and transmits a costimulatory signal by binding to OX40 ligand (OX40L) expressed on several cells with antigen‐presenting functions. Using a blocking monoclonal antibody (mAb) against murine OX40L, we investigated the role of OX40 in a murine model of corneal transplantation. C3H/He mouse corneas were transplanted to BALB/c mice orthotopically. Administration of anti‐OX40L mAb significantly reduced allograft rejection, and increased graft survival rate to 40% at 8 weeks after transplantation, while all corneas were rejected within 5 weeks in control IgG‐treated mice. Similar reduced rejection was observed when wild‐type donor corneas were transplanted to OX40L‐deficient recipients. In vitro study revealed that the anti‐OX40L mAb treatment reduced proliferative response and IFN‐γ production of draining lymph node cells in response to stimulation with donor alloantigen. These results demonstrate that OX40L blockade is effective for prolongation of corneal allograft survival by inhibiting recipient T cell activation.