Mihoko Shibuya

CD4+CD25−LAG3+ regulatory T cells controlled by the transcription factor Egr-2

Regulatory T cells (Tregs) are engaged in the maintenance of immunological self-tolerance and immune homeostasis. IL-10 has an important role in maintaining the normal immune state. Here, we show that IL-10-secreting Tregs can be delineated in normal mice as CD4+CD25−Foxp3− T cells that express lymphocyte activation gene 3 (LAG-3), an MHC-class-II-binding CD4 homolog. Although ≈2% of the CD4+CD25− T cell population consisted of CD4+CD25−LAG3+ T cells in the spleen, CD4+CD25−LAG3+ T cells are enriched to ≈8% in the Peyers patch. They are hypoproliferative upon in vitro antigenic stimulation and suppress in vivo development of colitis. Gene expression analysis reveals that CD4+CD25−LAG3+ Tregs characteristically express early growth response gene 2 (Egr-2), a key molecule for anergy induction. Retroviral gene transfer of Egr-2 converts naïve CD4+ T cells into the IL-10-secreting and LAG-3-expressing phenotype, and Egr-2-transduced CD4+ T cells exhibit antigen-specific immunosuppressive capacity in vivo. Unlike Foxp3+ natural Tregs, high-affinity interactions with selecting peptide/MHC ligands expressed in the thymus do not induce the development of CD4+CD25−LAG3+ Tregs. In contrast, the number of CD4+CD25−LAG3+ Tregs is influenced by the presence of environmental microbiota. Thus, IL-10-secreting Egr-2+LAG3+CD4+ Tregs can be exploited for the control of peripheral immunity.

Detection of autoantibodies to citrullinated BiP in rheumatoid arthritis patients and pro-inflammatory role of citrullinated BiP in collagen-induced arthritis

IntroductionAnti-citrullinated protein/peptide antibodies (ACPAs) are highly specific to rheumatoid arthritis (RA) patients and are thought to have a close relationship with the pathogenesis of arthritis. Several proteins, including fibrinogen, vimentin, and alpha-enolase, were reported as ACPA-target antigens, and their importance in RA pathogenesis was widely proposed. We identified citrullinated immunoglobulin binding protein (citBiP) as another ACPA target in RA patients and examined its pro-inflammatory role in arthritis.MethodsWe measured the levels of anti-citBiP, anti-BiP, and anti-cyclic citrullinated peptide (CCP) antibodies in the serum of RA patients (n = 100), systemic lupus erythematosus (SLE) patients (n = 60), and healthy controls (n = 30) using ELISA and immunoblotting. Epitope mapping was performed using 27 citBiP-derived peptides. In the mouse study, after DBA/1J mice were immunized with BiP or citBiP, serum titers of ACPAs were measured by ELISA and immunohistochemistry. The development of collagen-induced arthritis (CIA) was observed in BiP- or citBiP-pre-immunized mice.ResultsThe serum levels of anti-BiP and anti-citBiP antibodies were significantly increased in RA patients, although only anti-BiP antibodies were slightly increased in SLE patients. Interestingly, anti-citBiP antibody levels were higher than anti-BiP antibody levels in 72% of RA patients, whereas no significant increase in anti-citBiP antibody levels was detected in SLE patients and healthy controls. The serum levels of anti-CCP antibodies were correlated with those of anti-citBiP antibodies in RA patients (R2 = 0.41). Several citrulline residues of citBiP were determined to be major epitopes of anti-citBiP antibodies, one of which showed cross-reactivity with CCP. Immunization of DBA/1J mice with citBiP induced several kinds of ACPAs, including anti-CCP and anti-citrullinated fibrinogen antibodies. Pre-immunization with citBiP exacerbated CIA, and anti-CCP antibody levels were increased in citBiP-pre-immunized CIA mice.ConclusionsCitBiP is a newly described ACPA target that may play a pro-inflammatory role in arthritis.

Successful treatment with tocilizumab in a case of Cogan’s syndrome complicated with aortitis

A 69-year-old man with sensorineural hearing loss and iritis was diagnosed with atypical Cogan’s syndrome. He had several systematic manifestations: aortitis, meningitis, panniculitis and seronegative arthritis. Remission induced by treatment with high doses of prednisolone was followed by relapse within 1 year. Although his condition was resistant to various immunosuppressive drugs, including methotrexate, cyclosporine, azathioprine and adalimumab, his symptoms, inflammatory response and quality of life measures were successfully improved by tocilizumab, a humanized anti-interleukin-6 receptor antibody.

Autoantigen BiP-Derived HLA–DR4 Epitopes Differentially Recognized by Effector and Regulatory T Cells in Rheumatoid Arthritis

The balance between effector and regulatory CD4+ T cells plays a key role in the pathogenesis of rheumatoid arthritis (RA). The aim of this study was to examine whether the RA autoantigen BiP has epitopes for both effector and regulatory immunities.

Neuromyelitis optica spectrum disorder complicated with Sjogren syndrome successfully treated with tocilizumab: A case report.

A 38-year-old woman with relapsing longitudinal extensive transverse myelitis and Sjogrens syndrome (SS) was admitted with lower extremity muscle weakness. Studies showed high serum titer of anti-aquaporin4 antibody and gadolinium-enhanced-MRI T1-weighted lesions within thoracic cord. Clinical findings suggested neuromyelitis optica-spectrum disorder (NMO-SD). High-dose corticosteroids, plasma exchange and cyclophosphamide were not effective. After starting tocilizumab, her neurological findings gradually improved. This report describes the first evidence to show tocilizumab could be effective for NMO-SD with SS.

Transcription Factor Early Growth Response 3 Is Associated with the TGF-β1 Expression and the Regulatory Activity of CD4-Positive T Cells In Vivo

TGF-β1 is an important anti-inflammatory cytokine, and several regulatory T cell (Treg) subsets including CD4+CD25+Foxp3+ Tregs and Th3 cells have been reported to exert regulatory activity via the production of TGF-β1. However, it has not yet been elucidated which transcription factor is involved in TGF-β1 transcription. Early growth response 3 (Egr-3) is a zinc-finger transcription factor that creates and maintains T cell anergy. In this study, we found that Egr-3 induces the expression of TGF-β1 in both murine and human CD4+ T cells. Egr-3 overexpression in murine CD4+ T cells induced the production of TGF-β1 and enhanced the phosphorylation of STAT3, which is associated with TGF-β1 transcription. Moreover, Egr-3 conferred Ag-specific regulatory activity on murine CD4+ T cells. In collagen-induced arthritis and delayed-type hypersensitivity model mice, Egr-3–transduced CD4+ T cells exhibited significant regulatory activity in vivo. In particular, the suppression of delayed-type hypersensitivity depended on TGF-β1. In human tonsils, we found that CD4+CD25−CD45RO−lymphocyte activation gene 3 (LAG3)− T cells express membrane-bound TGF-β1 in an EGR3-dependent manner. Gene-expression analysis revealed that CD4+CD25−CD45RO−LAG3− T cells are quite different from conventional CD4+CD25+Foxp3+ Tregs. Intriguingly, the CD4+CD25−CD45RO−LAG3− T cells suppressed graft-versus-host disease in immunodeficient mice transplanted with human PBMCs. Our results suggest that Egr-3 is a transcription factor associated with TGF-β1 expression and in vivo regulatory activity in both mice and humans.

Characteristics of granulomatosis with polyangiitis patients in Japan

Abstract Objectives. Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a disease with significant ethnic differences. Reports on characteristics of Japanese granulomatosis with polyangiitis (GPA) patients are limited, and this study was undertaken to determine the characteristics of Japanese GPA patients. Methods. This was a retrospective chart study of 24 Japanese GPA patients. GPA was defined according to the European Medicines Agency algorithm. Results. The percentage of MPO-ANCA-positive patients was 33.3%, higher than the percentages reported in studies from Western countries. MPO-ANCA-positive GPA patients differed from PR3-ANCA-positive GPA patients in organs involved at diagnosis with MPO-ANCA-positive patients having nose and sinus involvement less frequently compared to PR3-ANCA-positive patients. Interstitial lung infiltrates were more common among MPO-ANCA-positive GPA patients compared to PR3-ANCA-positive GPA patients. Conclusion. Among Japanese GPA patients, the proportion of MPO-ANCA-positive patients is higher compared to reports from Western countries, and those patients are often different from the classical picture of GPA.

Tracheobronchitis with dyspnea in a patient with ulcerative colitis.

We herein report the case of a 42-year-old man with a one-year history of ulcerative colitis who presented with exacerbated bloody diarrhea, a productive cough and increasing breathing difficulties. Colonoscopy revealed typical deep ulcers in the rectosigmoid colon and atypical multiple sucker-like ulcers in the transverse colon, and computed tomography of the chest demonstrated wall thickening of the trachea and bronchi. In addition, bronchoscopy showed ulcers in the trachea, and histopathology disclosed findings of necrosis and inflammation of the subepithelial tissue of the trachea. Based on these findings, the patients respiratory symptoms were strongly suspected to be due to ulcerative colitis-related tracheobronchitis. Treatment with systemic corticosteroids subsequently resulted in a rapid clinical improvement.

A new T-cell activation mode for suboptimal doses of antigen under the full activation of T cells with different specificity

Loss of tolerance for autoantigens is a common feature in autoimmune diseases. Bystander T‐cell activation is the activation of T cells to produce functional changes through TCR‐independent stimulation. Although bystander activation may be related to tolerance loss to multiple autoantigens, the activation mechanism of T cells directed to an autoantigen with limited amount is not clear. We investigated an activation mode of T cells (designated as “associator T cells”) directed to a suboptimal dose of cognate antigen X in the presence of fully activated T cells (designated as “responder T cells”) directed to an optimal dose of antigen Y. In in vitro coculture, the activation of associator T cells was dependent on the presentation of antigen X, and soluble factors from activated responder T cells were not sufficient. Therefore, we conclude this activation mode is different from bystander activation and named it “extended antigen priming (EAP)”. T cells with EAP showed a different phenotype compared to conventionally primed cells, suggesting the unique nature of EAP. Intriguingly, EAP was dependent on the CD40–CD40L signaling pathway. Thus, the EAP model is a T‐cell activation mode for suboptimal dose of antigen and presumably related to the immune response to autoantigens in autoimmune status.

Polymorphic lymphoproliferative disorders in patients with rheumatoid arthritis are associated with a better clinical outcome

Abstract Objectives: The characteristics of lymphoproliferative disorders (LPD) in patients with rheumatoid arthritis (RA) remain unclear. Therefore, we retrospectively analyzed the clinical characteristics of these patients in our department. Methods: Twenty RA patients who developed LPD between April 2003 and August 2016 in our department were analyzed. Results: All of the RA patients who developed LPD had been treated with methotrexate (MTX). The median weekly and total dosages of MTX were 6.8 mg/week and 2530 mg, respectively. The median duration of MTX administration was eight years. Nineteen patients (95%) achieved complete remission (CR) and 15 (75%) achieved CR with MTX cessation alone. Based on the pathological findings, we divided MTX-associated LPD patients into two groups (n = 16); polymorphic LPD (31%) and other groups. CR with MTX cessation alone was achieved in 5 (100%) and 6 (54.5%) patients in the polymorphic LPD and other groups, respectively (p = .12). Moreover, the duration from the cessation of MTX to CR was significantly shorter in the polymorphic LPD group than in the other group (5.3 months vs 12.6 months, p = .01, respectively). Conclusion: Polymorphic LPD, which was the most frequent pathological diagnosis in this cohort, was associated with a higher incidence of CR and a significantly shorter duration to CR.