Masashi Narazaki

Osaka City University, Ōsaka, Ōsaka, Japan

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Publications (64)441.85 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Interleukin-6 (IL-6) is a cytokine with redundant and pleiotropic activities, and its synthesis is tightly regulated by transcriptional and posttranscriptional mechanisms. When infections and tissue injuries occur, IL-6 synthesis is promptly induced and provides an emergent signal that contributes to host defense through the stimulation of acute-phase responses, immune reactions, and hematopoiesis. After the environmental stress is removed from the host, the production of IL-6 is terminated. However, dysregulated continual synthesis of IL-6 is involved in the development of chronic inflammatory autoimmune diseases. For this reason, tocilizumab, a humanized anti-IL-6 receptor antibody, was developed. Worldwide clinical trials have demonstrated the outstanding efficacy of tocilizumab in rheumatoid arthritis, systemic juvenile idiopathic arthritis, and Castleman's disease; thus, a new era has come for the treatment of these diseases, which were previously considered intractable. Moreover, favorable results from off-label use of tocilizumab strongly suggest that it will be widely applicable for various refractory inflammatory autoimmune diseases. In this context, the mechanism for the continual synthesis of IL-6 needs to be elucidated in order to investigate the pathogenesis of specific diseases and to facilitate the development of more specific therapeutic strategies.
    Seminars in Immunology 01/2014; · 5.93 Impact Factor
  • European journal of dermatology : EJD. 12/2013;
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    ABSTRACT: The signalling pathway that comprises JAK kinases and STAT proteins (for signal transducer and activator of transcription) is important for relaying signals from various cytokines outside the cell to the inside. The feedback mechanism responsible for switching off the cytokine signal has not been elucidated. We now report the cloning and characterization of an inhibitor of STAT activation which we name SSI-1 (for STAT-induced STAT inhibitor-1). We found that SSI-1 messenger RNA was induced by the cytokines interleukins 4 and 6 (IL-4, IL-6), leukaemia-inhibitory factor (LIF), and granulocyte colony-stimulating factor (G-CSF). Stimulation by IL-6 or LIF of murine myeloid leukaemia cells (M1 cells) induced SSI-1 mRNA expression which was blocked by transfection of a dominant-negative mutant of Stat3, indicating that the SSI-1 gene is a target of Stat3 (refs 4, 5, 6, 7). Forced overexpression of SSI-1 complementary DNA interfered with IL-6- and LIF-mediated apoptosis and macrophage differentiation of M1 cells, as well as IL-6 induced tyrosine-phosphorylation of a receptor glycoprotein component, gp130, and of Stat3. When SSI-1 is overexpressed in COS7 cells, it can associate with the kinases Jak2 and Tyk2. These findings indicate that SSI-1 is responsible for negative-feedback regulation of the JAK-STAT pathway induced by cytokine stimulation.
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    ABSTRACT: Objectives: The retention of the anti-rheumatic agent tocilizumab (TCZ) has not been well documented in patients with rheumatoid arthritis (RA). We conducted an observational study to compare the retention of TCZ and anti-tumour necrosis factor (TNF) drugs in the treatment of patients with RA. Method: We reviewed continuation rates and causes of discontinuation of biological agents (biologics) by assessing medical records of patients with RA who were administered biologics at our institute from September 1999 to April 2012, using the Osaka University Biologics for Rheumatic Diseases (BiRD) registry. Results: A total of 401 patients were included. TCZ, infliximab (IFX), etanercept (ETN), and adalimumab (ADA) were administered to 97, 103, 143, and 58 patients, respectively. There were some differences between the baseline characteristics of the groups. The median duration (range) of TCZ, IFX, ETN, and ADA administration was 2.5 (0.1-12.6), 1.9 (0.0-7.7), 2.9 (0.0-11.3), and 1.3 (0.0-3.4) years, respectively. Continuation rates for TCZ and ETN were significantly higher than those for IFX and ADA. Multivariate analyses showed that discontinuation due to lack or loss of efficacy was significantly less common in the TCZ group than in the other groups. Discontinuation due to overall adverse events was not significantly different between treatment groups. Conclusion: TCZ and ETN show better retention than IFX or ADA in the treatment of RA.
    Scandinavian journal of rheumatology 03/2013; · 2.51 Impact Factor
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    ABSTRACT: Systemic sclerosis (SSc) presents stiffness of extremities due to sclerosis of the tissue especially at fingers, hands, and forearms. Here we report the case of a patient with diffuse cutaneous SSc who was administered anti-interleukin-6 receptor antibody tocilizumab (TCZ). Skin condition of SSc is evaluated by pinching the skin according to the Rodnan skin score, but sometimes tissue atrophy results in overestimation of the condition. To understand how the extremities softened after initiation of TCZ, we observed mobility of extremities. Range of motion (ROM) of joints was measured every four months after initiation of TCZ. The patient presented not only reduction of Rodnan score but also amelioration of mobility of extremities. The Rodnan skin score reduced from 35 to 7 within sixteen months, and ROM of most joints except ankle was expanded.
    Modern Rheumatology 03/2013; · 1.72 Impact Factor
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    ABSTRACT: The cytokine interleukin (IL)-6 has a wide range of biological activities. It contributes to host defense against pathogens by inducing immune responses, hematopoiesis, and acute-phase reactions. However, dysregulation of IL-6 production plays a significant pathological role in various autoimmune and chronic inflammatory disorders. Because IL-6 blockade was anticipated to provide a novel strategy for the treatment of such diseases, tocilizumab, a humanized anti-IL-6 receptor antibody, was developed. Clinical trials have demonstrated the efficacy of tocilizumab for patients with moderate to severe rheumatoid arthritis, resulting in approval in more than 90 countries worldwide of this innovative biologic for the treatment of rheumatoid arthritis. Tocilizumab was also approved in Japan for the treatment of Castleman's disease and juvenile idiopathic arthritis. Results of recent pilot or case studies have indicated that tocilizumab may become a novel drug for various other autoimmune disorders, including systemic lupus erythematosus, systemic sclerosis, polymyositis, and vasculitis syndrome, as well as inflammatory disorders such as adult-onset Still's disease, Crohn's disease, amyloid A amyloidosis, polymyalgia rheumatica, and spondylarthritides. It has been demonstrated that an imbalance of CD4-positive T-helper subsets [Th17 and/or Th1 >> regulatory T cells (Treg)] plays a major role in the development of several autoimmune disorders. In murine models of autoimmune disorders, the anti-IL-6 receptor antibody induced Treg and inhibited Th17 and/or Th1 differentiation, indicating that tocilizumab treatment may be able to repair this imbalance in human diseases as well. Drug Dev Res 72:717–732, 2011. © 2011 Wiley Periodicals, Inc.
    Drug Development Research 12/2011; 72(8). · 0.87 Impact Factor
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    ABSTRACT: A 47-year-old female patient with Behçet's disease had been treated with colchicine, prednisolone, cyclosporine A, and infliximab. Because she relapsed, however, treatment with tocilizumab, a humanized anti-interleukin 6 receptor antibody, was started. This treatment suppressed the patient's clinical manifestations, including ocular attacks, for 1 year and improved her visual acuity. This experience indicates that tocilizumab may constitute a therapeutic option for refractory Behçet's disease.
    Modern Rheumatology 07/2011; 22(2):298-302. · 1.72 Impact Factor
  • Rheumatology (Oxford, England) 07/2011; 50(7):1344-6. · 4.24 Impact Factor
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    Toshio Tanaka, Masashi Narazaki, Tadamitsu Kishimoto
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    ABSTRACT: Interleukin (IL)-6 is a cytokine with multiple biological activities. It contributes to host defense against pathogens, whereas accelerated production of IL-6 plays a significant pathological role in various diseases. Clinical trials have demonstrated the efficacy of tocilizumab, a humanized anti-IL-6 receptor antibody, for patients with rheumatoid arthritis, Castleman's disease or juvenile idiopathic arthritis, leading to approval of this innovative drug for the treatment of these diseases. Since IL-6 has been demonstrated to play a significant role in the development of various other autoimmune and inflammatory diseases, tocilizumab can be expected to become a novel drug for such diseases as well.
    FEBS letters 03/2011; 585(23):3699-709. · 3.54 Impact Factor
  • Toshio Tanaka, Masashi Narazaki, Tadamitsu Kishimoto
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    ABSTRACT: Interleukin (IL)-6 is a typical cytokine featuring redundancy and pleiotropic activity. It contributes to host defense against pathogens, but dysregulation of IL-6 production plays a significant pathological role in various autoimmune and inflammatory diseases. Because IL-6 blockade was expected to constitute a novel strategy for the treatment of such diseases, tocilizumab, a humanized anti-IL-6 receptor antibody (anti-IL-6RAb), was developed. Clinical trials have demonstrated the efficacy of anti-IL-6RAb for patients with rheumatoid arthritis, Castleman's disease, and juvenile idiopathic arthritis, resulting in approval of this innovative biologic for the treatment of these diseases, and it can be expected to become a novel drug for various other autoimmune and inflammatory diseases. In murine models of autoimmune diseases, anti-IL-6RAb induces Treg and inhibits Th17 and/or Th1 differentiation, indicating that anti-IL-6RAb may be able to repair Th17/Treg imbalance in human diseases as well.
    Annual Review of Pharmacology 01/2011; 52:199-219. · 21.54 Impact Factor
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    ABSTRACT: A 65-year-old woman who had suffered from chronic graft-versus-host disease (GVHD) presented with extensive purpura and was diagnosed with acquired hemophilia A. Because she was refractory to corticosteroids and her condition was complicated with diabetes mellitus, glaucoma, and hypoglobulinemia, she was treated with tocilizumab. Tocilizumab treatment increased the activity of factor VIII in a rapid and sustained manner, leading to a reduction of the prednisolone dose. Tocilizumab may thus be an optional treatment modality for acquired hemophilia A.
    Modern Rheumatology 01/2011; 21(4):420-2. · 1.72 Impact Factor
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    ABSTRACT: SSc is an autoimmune disease characterized by fibrosis of the skin and internal organs. Although the aetiology remains uncertain, many reports have suggested that IL-6 is involved in SSc pathogenesis. Tocilizumab, an anti-IL-6 receptor antibody, is an anti-arthritis medicine that works through the blockade of IL-6 functions. To examine the effect of tocilizumab on SSc, we administered tocilizumab to two SSc patients. Two dcSSc patients were administered tocilizumab at 8 mg/kg once a month for 6 months. One patient had pulmonary fibrosis assessed by CT and spirometry, and the other had chronic renal failure caused by scleroderma renal crisis. Their skin condition was monitored with a Vesmeter and the modified Rodnan total skin score (mRTSS). Skin biopsies were obtained before and after the tocilizumab treatment to investigate the histological changes. After tocilizumab treatment, both patients showed softening of the skin with reductions of 50.7 and 55.7% in the total z-score of Vesmeter hardness and 51.9 and 23.0% in the mRTSS, respectively. Histological examination showed thinning of the collagen fibre bundles in the dermis. The creatinine clearance in the patient with chronic renal failure improved from 38 to 55 ml/min. However, the fibrotic changes in the lung in the other patient remained unchanged. In the two cases of SSc that we report here, softening of the skin was observed during the treatment with tocilizumab.
    Rheumatology (Oxford, England) 12/2010; 49(12):2408-12. · 4.24 Impact Factor
  • Toshio Tanaka, Atsushi Ogata, Masashi Narazaki
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    ABSTRACT: Tocilizumab is a humanized anti-IL-6 receptor monoclonal antibody, which binds to circulating soluble IL-6 receptor and membrane-expressed IL-6 receptor, inhibiting IL-6 binding to both forms of IL-6 receptor. Several Phase III clinical trials demonstrate the clinical efficacy of tocilizumab as monotherapy or with disease-modifying anti-rheumatic drugs for adult patients with moderately to severely active rheumatoid arthritis. Tocilizumab in combination with methotrexate after 24 weeks of treatment could induce disease remission in 30% of patients with rheumatoid arthritis refractory to anti-TNF antagonist therapy. The most common adverse reactions reported in clinical studies are upper respiratory tract infection, nasopharyngitis, headache, hypertension and mild, reversible increases in alanine aminotransferase enzymes. Serious adverse reactions include infections, gastrointestinal perforations and hypersensitivity reactions, including anaphylaxis. The clinical efficacy and safety of tocilizumab has led to the approval of this innovative drug for the treatment of rheumatoid arthritis in more than 70 countries worldwide.
    Expert Review of Clinical Immunology 11/2010; 6(6):843-54. · 2.89 Impact Factor
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    ABSTRACT: Ligand interaction with cognate cell-surface receptor often promotes receptor internalization, protecting cells from prolonged or excessive signaling from extracellular ligands. Compounds that induce internalization of surface receptors prevent ligand binding to cognate cell-surface receptors serving as inhibitors. Here, we show that synthetic polyriboguanosine (poly G) and oligo-deoxyriboguanosine (oligo G) reduce endothelial levels of surface neuropilin-1 (NRP1), a receptor shared by semaphorin 3A and vascular endothelial growth factor (VEGF), which plays critical roles in angiogenesis. Oligo G also reduces levels of cell-surface scavenger receptor expressed by endothelial cells I (SREC-I), but not levels of NRP2, gp130, CD31, VEGFR-1, or VEGFR-2. Poly or oligo A, T, and C do not promote NRP1 or SREC-I internalization. We find that oligo G binds to NRP1 with high affinity (Kd:1.3 ± 0.16 nM), bridges the extracellular domain of NRP1 to that of SREC-I, and induces coordinate internalization of NRP1 and SREC-I. In vitro, oligo G blocks the binding and function of VEGF(165) in endothelial cells. In vivo, intravitreal administration of oligo G reduces choroidal neovascularization in mice. These results demonstrate that synthetic oligo G is an inhibitor of pathologic angiogenesis that reduces cell-surface levels and function of NRP1 acting as an internalization inducer.
    Blood 10/2010; 116(16):3099-107. · 9.78 Impact Factor
  • Annals of the rheumatic diseases 10/2010; 70(6):1164-5. · 8.11 Impact Factor
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    Rheumatology (Oxford, England) 12/2009; 49(4):824-6. · 4.24 Impact Factor
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    Arthritis & Rheumatology 11/2009; 61(12):1762-4. · 7.48 Impact Factor
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    ABSTRACT: Interferon gamma (IFN-gamma) production is a critical step of antituberculosis (anti-TB) immune response. The purpose of this study was to determine the influences of biologics, including the interleukin (IL)-6 receptor-inhibitor tocilizumab (TCZ), and tumor necrosis factor (TNF) antagonists infliximab (INF) and etanercept (ETA), on Mycobacterium tuberculosis (MTB) antigen-induced IFN-gamma production. MTB antigen (ESAT-6 and CFP-10)-induced IFN-gamma-releasing assay was performed with or without addition of biologics (TCZ, ETA, and INF) using whole blood from patients with active TB. ETA and INF inhibited IFN-gamma production in a dose-dependent manner. In whole blood from TB patients, ESAT-6 stimulated significant production of IFN-gamma (1.30 +/- 1.95 IU/ml), and TCZ did not inhibit IFN-gamma production (1.56 +/- 1.88 IU/ml). IFN-gamma production by ESAT-6 was inhibited by ETA and INF (0.98 +/- 1.74, 0.75 +/- 1.66 IU/ml, respectively). CFP-10 stimulated significant production of IFN-gamma (1.46 +/- 1.60 IU/ml), and TCZ did not inhibit IFN-gamma production (1.51 +/- 1.77 IU/ml). IFN-gamma production by CFP-10 was inhibited by ETA and INF (0.91 +/- 0.99, 0.72 +/- 0.88 IU/ml, respectively). TCD did not inhibit MTB antigen-induced IFN-gamma production. As IFN-gamma production is important in antimycobacterial host defenses, the minimal influence of TCZ on IFN-gamma-releasing assay suggests a low risk of latent TB infection reactivation during tocilizumab therapy.
    Modern Rheumatology 11/2009; 20(2):130-3. · 1.72 Impact Factor
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    Annals of the rheumatic diseases 08/2009; 68(7):1235-6. · 8.11 Impact Factor
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    ABSTRACT: Overgrowth of the synovium plays an important role in the pathogenesis of rheumatoid arthritis (RA). Platelet-derived growth factor (PDGF) is one of the most potent mitogenic factors of synovial cells, and imatinib mesylate (imatinib) is a specific inhibitor of the PDGF receptor tyrosine kinase. The aim of this study was to elucidate the anti-rheumatic activity of imatinib. The in vivo effects of imatinib were assessed by evaluating the sequential manifestation of adjuvant-induced arthritis in rats using paw volume and clinical scores. Imatinib was found to inhibit rat adjuvant-induced arthritis, but the inhibitory effects were incomplete. To confirm the mechanism of anti-rheumatic-activity of imatinib, we assessed the in vitro effects of imatinib on the proliferation of RA synovial fibroblast-like cells (RASFs) using a MTT assay. Intracellular signaling of PDGF was evaluated by Western blot analysis. Platelet-derived growth factor was found to induce a significant proliferation of RASFs, while imatinib inhibited PDGF-induced proliferation of RASF. Imatinib also inhibited PDGF-induced phosphorylation of the PDGF receptor and Akt, whereas constitutive activated extracellular signal-regulated kinase was not inhibited by imatinib. In contrast, imatinib did not inhibit transforming growth factor beta- and basic fibroblast growth factor-induced proliferation of RASF. Oral administration of imatinib ameliorated adjuvant-induced arthritis in rats, and it inhibited PDGF-induced RASF proliferation through disruption of the PDGF-R to Akt kinase signaling pathway. Because imatinib cannot inhibit the non-PDGF-dependent proliferation of RASFs, the anti-rheumatic effect of imatinib may be incomplete. The development of inhibitors of RASF proliferation may lead to the successful treatment of RA.
    Modern Rheumatology 08/2009; 19(5):522-9. · 1.72 Impact Factor

Publication Stats

4k Citations
441.85 Total Impact Points


  • 2000–2014
    • Osaka City University
      • Department of Neurosurgery
      Ōsaka, Ōsaka, Japan
  • 1992–2011
    • Osaka University
      • • Division of Respiratory Medicine, Allergy and Rheumatic Diseases
      • • Division of Cellular and Molecular Biology
      • • Division of Environmental and Molecular Medicine
      • • Immunology Division
      Ibaraki, Osaka-fu, Japan
  • 2004–2010
    • National Institutes of Health
      • • Laboratory of Cellular Oncology
      • • Basic Research Laboratory
      • • Branch of HIV and AIDS Malignancy
      • • Branch of Experimental Transplantation and Immunology
      Bethesda, MD, United States
  • 2001
    • Osaka Prefectural Government
      Ōsaka, Ōsaka, Japan
    • American Society of Hematology
      American Fork, Utah, United States