Hitoshi Kohsaka

Tokyo Medical and Dental University, Edo, Tōkyō, Japan

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Publications (125)438.77 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: IntroductionBiological drugs are effective in patients with rheumatoid arthritis (RA), but increase severe infections. The CC chemokine receptor (CCR) 9 antagonist was effective for Crohn¿s disease without critical adverse effects including infections in clinical trials. The present study was carried out to explore the pathogenic roles of chemokine (C-C motif) ligand (CCL) 25 and its receptor, CCR9 in autoimmune arthritis and to study if the CCR9 antagonist could be a new treatment for RA.MethodsCCL25 and CCR9 expression was examined with immunohistochemistry and Western blotting. Concentration of interleukin (IL)-6, matrix metalloproteinase (MMP)-3 and tumor necrosis factor (TNF)-¿ was measured with enzyme-linked immunosorbent assays. Effects of abrogating CCR9 on collagen-induced arthritis (CIA) was evaluated using CCR9-deficient mice or the CCR9 antagonist, CCX8037. Fluorescence labeled-CD11b+ splenocytes from CIA mice were transferred to recipient CIA mice and those infiltrating into the synovial tissues of the recipient mice were counted.ResultsCCL25 and CCR9 proteins were found in the RA synovial tissues. CCR9 was expressed on macrophages, fibroblast-like synoviocytes (FLS) and dendritic cells in the synovial tissues. Stimulation with CCL25 increased IL-6 and MMP-3 production from RA FLS, and IL-6 and TNF-¿ production from peripheral blood monocytes. CIA was suppressed in CCR9-deficient mice. CCX8037 also inhibited CIA and the migration of transferred CD11b+ splenocytes into the synovial tissues.Conclusion The interaction between CCL25 and CCR9 may play important roles in cell infiltration into the RA synovial tissues and inflammatory mediator production. Blocking CCL25 or CCR9 may represent a novel safe therapy for RA.
    Arthritis research & therapy. 09/2014; 16(5):445.
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    ABSTRACT: Biological disease-modifying antirheumatic drugs (DMARDs) that inhibit aberrant immune reactions in rheumatoid arthritis (RA) cannot induce complete remission in all patients. Combination therapies using two biological DMARDs have failed to exert additive effects and increased serious infections. We have found that cell cycle inhibition of synovial fibroblasts with cyclin-dependent kinase (CDK) inhibitors ameliorated the disease in animal models of RA without attenuating acquired immunity. The objective of this study was to determine whether a clinically well-tolerated selective CDK 4/6 inhibitor (CDKI), palbociclib, is effective and whether combination with cytokine blockers acts additively without enhancing immune suppression.
    Annals of the rheumatic diseases. 08/2014;
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    ABSTRACT: Some of cannabinoids, which are chemical compounds contained in marijuana, are immunosuppressive. One of the receptors, CB receptor 1 (CB1), is expressed predominantly by the cells in the central nervous system, whereas CB receptor 2 (CB2) is expressed primarily by immune cells. Theoretically, selective CB2 agonists should be devoid of psychoactive effects. In this study, we investigated therapeutic effects of a selective CB2 agonist on arthritis.
    BMC Musculoskeletal Disorders 08/2014; 15(1):275. · 1.88 Impact Factor
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    ABSTRACT: In addition to the pivotal roles of mast cells in allergic diseases, recent data suggest that mast cells play crucial roles in a variety of autoimmune responses. However, their roles in the pathogenesis of autoimmune skeletal muscle diseases have not been clarified despite their distribution in skeletal muscle. Therefore, the objective of this study is to determine the roles of mast cells in the development of autoimmune skeletal muscle diseases. The number of mast cells in the affected muscle was examined in patients with dermatomyositis (DM) or polymyositis (PM). The susceptibility of mast cell-deficient WBB6F1-KitW/KitWv mice (W/Wv mice) to a murine model of polymyositis, C protein-induced myositis (CIM), was compared with that of wild-type (WT) mice. The effect of mast cell reconstitution with bone marrow-derived mast cells (BMMCs) on the susceptibility of W/Wv mice to CIM was also evaluated. The number of mast cells in the affected muscle increased in patients with PM as compared to patients with DM. W/Wv mice exhibited significantly reduced disease incidence and histological scores of CIM as compared with WT mice. The number of CD8+ T cells and macrophages in the skeletal muscles of CIM decreased in W/Wv mice compared to WT mice. Engraftment of BMMCs restored the incidence and histological scores of CIM in W/Wv mice. Vascular permeability in the skeletal muscle was elevated in WT mice but not in W/Wv mice upon CIM induction. Mast cells are involved in the pathogenesis of inflammatory myopathy.
    Arthritis research & therapy 03/2014; 16(2):R72. · 4.27 Impact Factor
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    ABSTRACT: Objective. To investigate the role of adhesion molecules in C protein-induced myositis (CIM), a murine model for polymyositis (PM).Methods. CIM was induced in wild type mice, L-selectin-deficient (L-selectin-/-) mice, ICAM-1-deficient (ICAM-1-/-) mice, and both L-selectin- and ICAM-1-deficient (L-selectin-/-ICAM-1-/-) mice. The severity of myositis, inflammatory cell infiltration, and mRNA expression in the inflamed muscles were examined. The effect of dendritic polyglycerol sulfate (dPGS), a synthetic inhibitor that suppresses the function of L-selectin and endothelial P-selectin, was also examined.Results. L-selectin-/- mice and L-selectin-/-ICAM-1-/- mice developed significantly less severe myositis compared to wild type mice, while ICAM-1 deficiency did not inhibit the development of myositis. L-selectin-/- mice transferred with wild type T cells developed myositis. Wild type mice treated with dPGS significantly diminished the severity of myositis compared to control-treated wild type mice.Conclusions. These data indicate that L-selectin plays a major role in the development of CIM, whereas ICAM-1 plays a lesser, if any, role in the development of CIM. L-selectin-targeted therapy may be a candidate for the treatment of PM. © 2014 American College of Rheumatology.
    Arthritis & Rheumatology. 03/2014;
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    ABSTRACT: Autoantibodies to aminoacyl-tRNA synthetases (ARSs) are useful in the diagnosis of idiopathic inflammatory myopathy (IIM) with interstitial pneumonia (IP). We developed an enzyme-linked immunosorbent assay (ELISA) system using a mixture of recombinant ARS antigens and tested its utility in a multicenter study. Methods: We prepared six recombinant ARSs: GST-Jo-1, His-PL-12, His-EJ and GST-KS expressed in Escherichia coli, and His-PL-7 and His-OJ expressed in Hi-5 cells. After confirming their antigenic activity, with the exception of His-OJ, we developed our ELISA system in which the five recombinant ARSs (without His-OJ) were mixed. Efficiency was confirmed using the sera from 526 Japanese patients with connective tissue disease (CTD) (IIM n = 250, systemic lupus erythematosus n = 91, systemic sclerosis n = 70, rheumatoid arthritis n = 75, Sjögren's syndrome n = 27 and other diseases n = 13), 168 with idiopathic interstitial pneumonia (IIP) and 30 healthy controls collected from eight institutes. IIPs were classified into two groups; idiopathic pulmonary fibrosis (IPF) (n = 38) and non-IPF (n = 130). Results were compared with those of RNA immunoprecipitation. Results: Sensitivity and specificity of the ELISA were 97.1% and 99.8%, respectively when compared with the RNA immunoprecipitation assay. Anti-ARS antibodies were detected in 30.8% of IIM, 2.5% of non-myositis CTD, and 10.7% of IIP (5.3% of IPF and 12.3% of non-IPF). Anti-ARS-positive non-IPF patients were younger and more frequently treated with glucocorticoids and/or immunosuppressants than anti-ARS-negative patients. Conclusion: A newly established ELISA detected anti-ARS antibodies as efficiently as RNA immunoprecipitation. This system will enable easier and wider use in the detection of anti-ARS antibodies in patients with IIM and IIP.
    PLoS ONE 01/2014; 9(1):e85062. · 3.53 Impact Factor
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    ABSTRACT: We describe a patient who developed fever, bilateral otitis media, destructive necrosis of the nasal cavity and multiple lung nodules. The patient fulfilled the American College of Rheumatology (ACR) classification criteria for Wegener’s granulomatosis (WG) and was also diagnosed as having WG by using the ACR classification tree. However, the diagnosis of T cell lymphoma was finally made by cervical lymph node biopsy, 2 years after disease onset. Rheumatologists should therefore aware of the pitfall of using diagnostic criteria and repetitive biopsy is strongly recommended for accurate diagnosis of WG.
    Modern Rheumatology 01/2014; 7(3):183-188. · 1.72 Impact Factor
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    ABSTRACT: A 64-year-old woman presented with an acute onset of myelitis and optic neuritis after 47 months of etanercept use for rheumatoid arthritis. Etanercept was discontinued and pulse methylprednisolone therapy (1000 mg/day for 3 days) was started, followed by a quick and complete resolution. Demyelination associated with antitumor necrosis factor agents, reported to develop mostly from 1 week to 12 months after the initiation of the agents, could develop after a few years and thus warrants vigilant monitoring.
    BMJ case reports. 01/2014; 2014.
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    ABSTRACT: We describe a case of severe dermatomyositis (DM) complicated by rhabdomyolysis, acute tubular necrosis, and hemophagocytosis. The case failed to respond to corticosteroids, but showed rapid and significant improvement after the addition of intravenous immunoglobulin (IVIG). While the prognosis of DM is poor when it is complicated by rhabdomyolysis, the early administration of IVIG has the potential to be the cornerstone of its management.
    Modern Rheumatology 11/2013; · 1.72 Impact Factor
  • Hitoshi Kohsaka
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    ABSTRACT: Abstract Steroid myopathy, characterized by muscle atrophy and weakness, is an adverse effect of high-dose steroid therapy. Weakness of proximal muscle that interferes with activities of daily living is a serious problem for patients with steroid myopathy. Here, we outline the pathogenic mechanism, diagnosis, and treatment of steroid myopathy. Recent studies have shown that steroid-mediated induction of ubiquitin ligases (atrogin-1, muscle RING finger-1) and suppression of mammalian/mechanistic target of rapamycin cause an imbalance between anabolism and catabolism of muscle proteins, resulting in muscle atrophy. Despite the progress in understanding the pathogenic mechanism, the diagnosis and treatment of steroid myopathy has not yet been established. Small changes in muscle enzymes, including CK, LDH, and aldolase, make it difficult to define diagnostic criteria. Furthermore, since there is no drug available for treating the disorder, the patients have no opinion except waiting for spontaneous recovery with steroid tapering and exercising. To address these issues, we introduce novel approaches involving branched-chain amino acids that aim at treatment and assessment of steroid myopathy.
    Brain and nerve = Shinkei kenkyū no shinpo 11/2013; 65(11):1375-80.
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    ABSTRACT: Objectives. To estimate the number of patients with polymyositis/dermatomyositis (PM/DM) in Japan and the prevalence rate and incidence rate of the disease. Methods. The electronic database in the nationwide registration system on intractable diseases from 2003 to 2010 was utilized to identify the number of prevalent and incident cases of PM/DM. The electronic data entry rate was used to establish the total number of registered cases. Results. The estimated total number of patients with PM/DM and the prevalence rate in Japan in 2010 were 17,000 and 13.2 per 100,000 population, respectively. The prevalence of PM/DM ranged from 10 to 13 per 100,000 population with a trend toward increasing over time. The incidence of PM/DM was estimated within the range 10-13 per 1,000,000 person-years, except for 2003. Conclusions. We report the prevalence and incidence of PM/DM recently in Japan for the first time at the nationwide population level. Because the prevalence seems to be increasing recently, continued monitoring of these epidemiologic features is required.
    Modern Rheumatology 10/2013; · 1.72 Impact Factor
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    ABSTRACT: Increased activity of osteoclasts is responsible for bone loss and joint destruction in rheumatoid arthritis. For osteoclast development and bone resorption activity, cytoskeletal organization must be properly regulated. MicroRNAs (miRNAs) are endogenous small noncoding RNAs that suppress expression of their target genes. This study was conducted to identify crucial miRNAs to control osteoclasts. miRNA expression in the bone marrow-derived macrophages (BMM) with or without receptor activator of nuclear factor kappaB ligand (RANKL) stimulation was analyzed by miRNA array. To examine the role of specific miRNAs in osteoclast formation, bone resorption activity and actin ring formation, the BMM were retrovirally transduced with miRNA antagomirs. To confirm whether the suppressive effects on osteoclastogenesis by miR-31 inhibition were mediated by targeting RhoA, osteoclast formation was analyzed in the presence of the RhoA inhibitor, exoenzyme C3. miR-31 was identified as one of the highly upregulated miRNAs during osteoclast development under RANKL stimulation. Inhibition of miR-31 by specific antagomirs suppressed the RANKL-induced formation of osteoclasts and bone resorption. Phalloidin staining of osteoclasts revealed that actin ring formation at the cell periphery was severely impaired by miR-31 inhibition, and clusters of small ringed podosomes were observed instead. In these osteoclasts, expression of RhoA, one of the miR-31 target genes, was upregulated by miR-31 inhibition in spite of the impaired osteoclastogenesis. Treatment with the RhoA inhibitor, exoenzyme C3, rescued the osteoclastogenesis impaired by miR-31 inhibition. miR-31 controls cytoskeleton organization in osteoclasts for optimal bone resorption activity by regulating the expression of RhoA.
    Arthritis research & therapy 09/2013; 15(5):R102. · 4.27 Impact Factor
  • Rheumatology (Oxford, England) 06/2013; · 4.24 Impact Factor
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    ABSTRACT: OBJECTIVES: To evaluate the safety and efficacy of retreatment with tocilizumab (TCZ) in patients who had participated in the DREAM study (Drug free remission/low disease activity after cessation of tocilizumab [Actemar] monotherapy study) and had experienced loss of efficacy. METHODS: Patients were retreated with TCZ or other disease modifying antirheumatic drugs (DMARDs). Disease activity was measured using the 28-joint disease activity score (DAS28) for 12 weeks. RESULTS: A total of 164 eligible patients, including 161 who experienced loss of efficacy within 52 weeks of the DREAM study, resumed treatment: 157 with TCZ and 7 with DMARDs and/or infliximab. Of TCZ-treated patients, 88.5 % (139 patients) achieved DAS28 <2.6 within 12 weeks, whereas among patients treated with DMARDs and/or infliximab only 14.3 % (1 patient) achieved DAS28 <2.6. Adverse events were observed in 70 TCZ-treated patients (44.0 %), but no serious infusion reactions were observed. CONCLUSIONS: Retreatment with TCZ was well-tolerated and effective in patients who had responded to the preceding TCZ monotherapy but had experienced loss of efficacy after cessation of TCZ.
    Modern Rheumatology 05/2013; · 1.72 Impact Factor
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    ABSTRACT: OBJECTIVES: To investigate the duration of remission and low disease activity (LDA) after cessation of tocilizumab (TCZ) treatment in rheumatoid arthritis patients who showed remission or LDA as assessed by DAS28 in response to preceding TCZ monotherapy, and to explore the factors contributing to prolonged efficacy duration. METHODS: Disease activity was monitored for 56 weeks. The rate of continued efficacy was estimated by Kaplan-Meier curves. RESULTS: A total of 187 patients were eligible. At baseline of this study, median disease duration was 7.8 years, preceding TCZ treatment period was 4.0 years and DAS28 was 1.5. The rate of continued LDA at 52 weeks was 13.4 % according to the Kaplan-Meier estimate. 19 patients (10 %) were completely drug-free and 17 patients (9.1 %) fulfilled DAS28 remission at 52 weeks. Multivariate Cox regression analysis identified low serum IL-6 and normalisation of MMP-3 levels at cessation of TCZ as independent predictive markers for longer duration of LDA. In patients with low serum IL-6 (<12.9 pg/mL) and normal MMP-3 levels, the rate of continued LDA reached 38.0 % at 52 weeks. CONCLUSIONS: TCZ monotherapy may induce biologics-free remission or LDA without concomitant use of synthetic DMARDs. Serum levels of IL-6 and MMP-3 are useful markers for identifying patients who could discontinue TCZ without acute disease flare.
    Modern Rheumatology 05/2013; · 1.72 Impact Factor
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    ABSTRACT: A 51-year-old woman presented with one-month history of fever, productive cough, dyspnea, hoarseness and polyarthritis. Computed tomography (CT) depicted diffuse bronchotracheal stenosis, which deteriorated in exhalation. Three-dimensional CT revealed airway stenosis from the trachea to the lobar bronchi. We made a diagnosis of relapsing polychondritis (RP). Administration of high-dose glucocorticoid and oral cyclophosphamide resolved the symptoms and the bronchial stenosis. It was noteworthy that all features presented were bronchial chondritis and polyarthritis. RP should be considered when patients have polyarthritis with respiratory symptoms. The dynamic expiratory CT and three-dimensional image reconstructions are useful for detecting and following up bronchotracheal involvement.
    Modern Rheumatology 03/2013; · 1.72 Impact Factor
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    ABSTRACT: The IL-6-triggered positive feedback loop for NFκB signaling (or the IL-6 amplifier/Imflammation amplifier) was originally discovered as a synergistic-activation signal that follows IL-17/IL-6 stimulation in nonimmune cells. Subsequent results from animal models have shown that the amplifier is activated by stimulation of NFκB and STAT3 and induces chemokines and inflammation via an NFκB loop. However, its role in human diseases is unclear. Here, we combined two genome-wide mouse screens with SNP-based disease association studies, revealing 1,700 genes related to the IL-6 amplifier, 202 of which showed 492 indications of association with ailments beyond autoimmune diseases. We followed up on ErbB1 from our list. Blocking ErbB1 signaling suppressed the IL-6 amplifier, whereas the expression of epiregulin, an ErbB1 ligand, was higher in patients with inflammatory diseases. These results indicate that the IL-6 amplifier is indeed associated with human diseases and disorders and that the identified genes may make for potential therapeutic targets.
    Cell Reports 02/2013; · 7.21 Impact Factor
  • Article: Reply.
    Naoko Okiyama, Hitoshi Kohsaka
    Arthritis & Rheumatology 02/2013; · 7.48 Impact Factor
  • Rheumatology (Oxford, England) 01/2013; · 4.24 Impact Factor

Publication Stats

1k Citations
438.77 Total Impact Points

Institutions

  • 1989–2014
    • Tokyo Medical and Dental University
      • • Department of Hematology
      • • Department of Medicine and Rheumatology
      • • Department of Dermatology
      • • Department of Medicine
      • • Department of Internal Medicine
      Edo, Tōkyō, Japan
  • 2012–2013
    • Saitama Medical University
      • Department of Public Health
      Saitama, Saitama, Japan
  • 2007–2010
    • RIKEN
      Вако, Saitama, Japan
  • 1996
    • National Cheng Kung University
      臺南市, Taiwan, Taiwan
  • 1995
    • Tazuke Kofukai Medical Research Institute, Kitano Hospital
      Ōsaka, Ōsaka, Japan
  • 1993–1995
    • University of California, San Diego
      • Department of Medicine
      San Diego, CA, United States
  • 1989–1990
    • The University of Tokyo
      Edo, Tōkyō, Japan