Nobuyoshi Kitaichi

Genome-wide association studies identify IL23R - IL12RB2 and IL10 as Behçet's disease susceptibility loci

Behçets disease is a chronic systemic inflammatory disorder characterized by four major manifestations: recurrent ocular symptoms, oral and genital ulcers and skin lesions. We conducted a genome-wide association study in a Japanese cohort including 612 individuals with Behçets disease and 740 unaffected individuals (controls). We identified two suggestive associations on chromosomes 1p31.3 (IL23R-IL12RB2, rs12119179, P = 2.7 × 10−8) and 1q32.1 (IL10, rs1554286, P = 8.0 × 10−8). A meta-analysis of these two loci with results from additional Turkish and Korean cohorts showed genome-wide significant associations (rs1495965 in IL23R-IL12RB2, P = 1.9 × 10−11, odds ratio = 1.35; rs1800871 in IL10, P = 1.0 × 10−14, odds ratio = 1.45).

Induction of regulatory T cells by the immunomodulating cytokines α-melanocyte-stimulating hormone and transforming growth factor-β2

Recently, we have reported that the cytokines α‐melanocyte‐stimulating hormone (α‐MSH) and transforming growth factor‐β2 (TGF‐β2) work in synergy to induce the activation of regulatory T (Treg) cells. When we used α‐MSH and TGF‐β2 to generate ocular autoantigen‐specific Treg cells and adoptively transferred them into mice susceptible to experimental autoimmune uveoretinitis (EAU), there was suppression in the incidence and severity of EAU. Specificity to a retinal autoantigen was required for the Treg cells to suppress EAU. When stimulated, these Treg cells produced TGF‐β1, and their production of interferon‐γ, interleukin (IL)‐10, and IL‐4 was suppressed. Also, the Treg cells are suppressed in their proliferative response. Our results demonstrate that α‐MSH with TGF‐β2 induce Treg cells that can subdue a tissue‐specific autoimmune response. This also promotes the possibility of using these immunomodulating cytokines to purposely induce antigen‐specific Treg cells to prevent and suppress autoimmune disease.

Thrombospondin plays a vital role in the immune privilege of the eye

Purpose: The role of thrombospondin (TSP)-1 in TGF-β acti- vation and T-cell suppression was studied in the retinal pigment epithelial (RPE) cells, a monolayer of pigmented cells that line the subretinal space, an immune-privileged site in the eye. Methods: Posterior eyecups were prepared by excising the anterior segment, lens, and retina from enucleated eyes of C57BL/6, thrombospondin-1 knockout (TSP-1KO), and TGF-β2 receptor II double-negative (TGF-β 2R II DN) mice, leaving behind a healthy monolayer of RPE resting on choroid and sclera. Serum-free medium was added to these RPE eyecups, and, after various time intervals, supernatants (SNs) were removed and tested. Results: SN so fa ne xvivo culture of RPE cells from C57BL/6 mice were shown to inhibit both antigen and anti-CD3 activation of T cells, partially due to constitutive production of TGF-β and to the ability of RPE to activate the latent form of TGF-β .A ctivation of TGF-β was entirely dependent on TSP- 1, also produced by RPE. SNs of RPE from TSP-1KO mice failed to inhibit T-cell activation. Ovalbumin (OVA)-specific delayed hypersensitivity (DH) was not impaired when OVA was injected either into the subretinal space or into the anterior chamber of TSP-1KO mice before OVA immunization. Moreover, experimental autoimmune uveoretinitis was significantly more intense in eyes of TSP-1KO mice and failed to undergo spontaneous resolution unlike wild- type mice. Conclusions: Production of both TSP-1 and active TGF-β by RPE is essential to the creation and maintenance of immune privilege in the subretinal space and that the immune privilege limits the severity and duration of retinal inflammation due to autoimmunity.

Ocular features of behçet's disease : An international collaborative study

Objective: To investigate the clinical features of ocular lesions in Behçet’s disease in different countries. Methods: A descriptive questionnaire survey was performed. Results: 25 eye centres in 14 countries returned questionnaires on prevalent cases in 2006. Clinical data were analysed on 1,465 patients with ocular lesions. Recurrent oral aphthous ulcers were reported in 94.5%, skin lesions in 69.5% and genital ulcers in 61.4%. Most of the patients had bilateral and recurrent intraocular inflammation. Poor visual acuity was seen in 18.9% in women, but 24.8% in men (p<0.01). Panuveitis was seen more in men than in women (p<0.01). 23% of the patients had visual acuity equal to or worse than 20/200 at the final visit. The patients with poor vision were more frequently in India, Iran and Japan than in other countries (p<0.01). Conclusions: We report the largest contemporary international case series of patients with ocular involvement in Behçet’s disease. Panuveitis was significantly more frequent in men than women, and men tended to have a worse visual prognosis. There were some differences in the clinical pattern of Behçet’s disease in different countries. Despite modern treatment, the disease still carries a poor visual prognosis with one-quarter of the patients blind.

Inducible immune regulation following autoimmune disease in the immune-privileged eye

The immune‐privileged eye has the potential to induce regulatory immunity along with local mechanisms of immunosuppression. Rodent models of human autoimmune uveoretinitis [experimental autoimmune uveoretinitis (EAU)] recover without spontaneous recurrence of uveitis, which differs from uveitis in some humans. This raises the possibility that the mechanism of immune privilege in the rodent eye can reimpose itself during autoimmune uveoretinitis and re‐establish tolerance to autoantigen. To investigate this possibility, we examined the spleens of EAU‐recovered mice for regulatory immunity. We detected regulatory immunity when we adoptively transferred post‐EAU spleen cells into other mice immunized for EAU. We could not detect this regulatory immunity in enucleated mice nor in naive mice. Moreover, unlike the mechanisms of anterior chamber‐associated immune deviation, the suppression was only mediated by post‐EAU CD4+ T cells, which required activation with autoantigen presented by post‐EAU spleen antigen‐presenting cells (APC). Our results demonstrate that when the immune‐privileged ocular microenvironment recovers from an autoimmune response, it has influenced systemic immunity to retinal autoantigen by affecting APC and mediating induction of potential regulatory CD4+ T cells laying in wait in the post‐EAU spleen for restimulation.

The diminishment of experimental autoimmune encephalomyelitis (EAE) by neuropeptide alpha-melanocyte stimulating hormone (α-MSH) therapy

The neuropeptide alpha-melanocyte stimulating hormone (alpha-MSH) plays an important role in immune privilege by its suppression of inflammation, and its induction of regulatory T cells. This finding led us to test the possibility that we can use alpha-MSH to suppress autoimmune diseases, and promote re-establishment of immune tolerance to autoantigens. To test this possibility, SJL mice with experimental autoimmune encephalomyelitis (EAE) were injected with alpha-MSH at the first signs of paralysis. The alpha-MSH-treated mice in comparison with untreated EAE mice had a profound diminishment in the severity and tempo of EAE. The spleen cells in alpha-MSH-treated EAE produced TGF-beta in response to PLP-antigen stimulation in contrast to untreated mice spleen cells that produced IFN-gamma. When the alpha-MSH-treated EAE mice were reimmunized there was a delay of a week before the second episode of EAE. Although this delay maybe because of the induction of TGF-beta-producing spleen cells by the alpha-MSH-treatment, it was not adequate to suppress IFN-gamma-production by PLP-antigen stimulated spleen cells from untreated mice, nor able to suppress the eventual second episode of EAE. Therefore, the injection of alpha-MSH at the onset of paralysis is extremely effective in diminishing the severity and tempo of EAE, and the subsequent induction of potential PLP-specific Treg cells suggests that an alpha-MSH therapy could be attempted as part of a therapeutic regiment to impose immunoregulation and immunosuppression on an autoimmune disease of the central nervous system.

Diminution of experimental autoimmune uveoretinitis (EAU) in mice depleted of NK cells

To evaluate the potential role of NK1.1 (CD161c) cells in autoimmune uveoretinitis, we treated experimental autoimmune uveoretinitis (EAU)‐susceptible mice with anti‐CD161c antibodies (PK136) to deplete natural killer (NK) cells. Injection of anti‐CD161c antibodies deleted NK cells from the peripheral blood of EAU‐susceptible mice. The T cell proliferative response against the ocular autoantigen K2 was not suppressed in mice treated with anti‐CD161c antibody when compared with T cells from control mice. Although mice treated with anti‐CD161c developed EAU, the clinical severity on days 17 and 19 after induction of EAU was significantly mild in anti‐CD161c‐treated mice compared with control mice. In addition, the histopathological severity of EAU was significantly milder in mice treated with anti‐CD161c antibodies than controls 21 days after induction of EAU. Our results indicate that the severity of EAU is augmented by NK1.1+ NK cells.

Osteopontin Aggravates Experimental Autoimmune Uveoretinitis in Mice

Human endogenous uveitis is a common sight-threatening intraocular inflammatory disease and has been studied extensively using a murine model of experimental autoimmune uveoretinitis (EAU). It is possibly mediated by Th1 immune responses. In the present study, we investigated the role of osteopontin (OPN), a protein with pleiotropic functions that contributes to the development of Th1 cell-mediated immunity. Accompanying EAU progression, OPN was elevated in wild-type (WT) mice that had been immunized with human interphotoreceptor retinoid-binding protein (hIRBP) peptide 1–20. OPN-deficient (OPN−/−) mice showed milder EAU progression in clinical and histopathological scores compared with those of WT mice. The T cells from hIRBP-immunized OPN−/− mice exhibited reduced Ag-specific proliferation and proinflammatory cytokine (TNF-α and IFN-γ) production compared with those of WT T cells. When hIRBP-immunized WT mice were administered M5 Ab reacting to SLAYGLR sequence, a cryptic binding site to integrins within OPN, EAU development was significantly ameliorated. T cells from hIRBP-immunized WT mice showed significantly reduced proliferative responses and proinflammatory cytokine production upon stimulation with hIRBP peptide in the presence of M5 Ab in the culture. Our present results demonstrate that OPN may represent a novel therapeutic target to control uveoretinitis.

Increased Osteopontin Levels in the Vitreous of Patients with Diabetic Retinopathy

Purpose: Osteopontin (OPN) has diverse functions such as cell adhesion, chemoattraction, immunomodulation, and angiogenesis. The aim of this study is to analyze the OPN levels in vitreous fluid obtained from diabetic retinopathy (DR) and non-DR patients. Methods: Nineteen patients out of 11 with DR and 8 without DR underwent pars plana vitrectomy and vitreous fluid was obtained simultaneously. Two distinct sandwich enzyme-linked immunosorbent assay systems (systems 1 and 2) were applied, which have been developed in our laboratories to quantify the OPN concentrations in vitreous fluid. Results: The non-thrombin-cleaved full-length OPN levels in the vitreous fluid were 921.63 ± 45.38 ng/ml in DR and 632.80 ± 83.43 ng/ml in non-DR using system 1. Also, vitreous thrombin-cleaved and noncleaved OPN levels were increased to 2,109.22 ± 151.651 and 1,651.13 ± 229.82 ng/ml in patients with DR and non-DR using system 2. The vitreous OPN levels were significantly higher in DR than those in non-DR (p < 0.01 by system 1 and p < 0.05 by system 2). Conclusion: Thrombin-cleaved and noncleaved vitreous OPN levels in patients with DR were increased compared with control subjects, suggesting that OPN plays a potential role in the pathogenesis of diabetic retinal ischemia.

Mutation screening of the CARD15 gene in sarcoidosis

CARD15 was first identified as a susceptibility gene for Crohns disease. More recently, CARD15 mutations were shown to be associated with the pediatric granulomatous inflammatory diseases, Blau syndrome and early-onset sarcoidosis (EOS). The aim of the present study was to evaluate whether CARD15 variants also play a role in patients with ordinary sarcoidosis other than EOS. We enrolled 135 Japanese sarcoidosis patients with uveitis as well as 95 healthy individuals and performed mutation analysis by direct sequencing of CARD15 exon 4. Direct DNA sequencing in the sarcoidosis patients showed eight CARD15 variants, including five novel mutations (13402C>T, 13543C>T, 13775C>A, 13937G>A, and 14079C>T). Compared with healthy individuals, CARD15 mutations are not common in the Japanese patients with sarcoidosis. Based on the results, we examined the clinical manifestations in patients with sarcoidosis according to their CARD15 mutations. Sarcoidosis patients with these mutations have no specific clinical features with regard to course of the disease or disease severity. Our results indicate that in general, CARD15 mutations may not contribute to the risk of sarcoidosis.