Interleukin (IL)-6 is a pleiotropic cytokine that has crucial roles in the regulation of immune response, inflammation and hematopoiesis. Recently, a new inflammatory helper T cell subset which produces IL-17A (IL-17), termed Th17 cells was identified and has been reported to be involved in the development and pathogenesis of collagen induced arthritis (CIA) and experimental autoimmune encephalomyelitis (EAE), which are known as the mouse model of rheumatoid arthritis and multiple sclerosis, respectively. It has been demonstrated that IL-6 together with TGF-β induces the differentiation of Th17 cells from naive helper T cells in vitro. However, IL-6 independent pathway of Th17 differentiation has also been reported, suggesting that the role of IL-6 in vivo in these diseases remains unclear. With the treatment of anti-IL-6R antibody in CIA and EAE, we could suppress the differentiation of antigen specific Th17 cells and the onset of diseases. These results indicate that IL-6 is involved in the induction of Th17 cells in vivo, and anti-IL-6R antibody might be a promising therapy of Th17-mediated autoimmune diseases.

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  The idiopathic inflammatory myopathies, polymyositis (PM) and dermatomyositis (DM), are evaluated as systemic autoimmune diseases without the pathology determined. Past immunohistochemical findings suggested that the effector response is driven predominantly by CD4 T cells and by humoral immunity in DM, and by cytotoxic T cells in PM. However, histological observations of muscle tissue do not necessarily distinguish DM and PM. Thus, the two diseases including amyopathic DM might represent a spectrum of illness in which some patients suffer only from a muscle disease or from a skin disease.
  In comparison with research studies on other rheumatic diseases, there are much fewer research studies conducted on PM/DM. The relationship between PM and DM is not clear yet. We reviewed past clinical and basic research on the pathology of PM/DM, including research on relevant T cells, B cells and cytokines.

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  Interleukin-6 (IL-6) has been demonstrated to play a pivotal role in CNS trauma as a proinflammatory cytokine which regulates inflammatory response. Not only being a mediator of inflammation, but IL-6 induces neural stem/progenitor cells to undergo astrocytic differentiation selectively in the injured CNS. These effects are considered to coordinate to prevent the CNS repair after traumatic injury. Consistently, we previously reported that the administration of anti-IL-6 receptor antibody (MR16-1) immediately after spinal cord injury in mice decreased the number of invading inflammatory cells and the severity of connective tissue scar formation, and led to improved functional recovery. These findings suggest that neutralization of IL-6 signaling in the acute phase of SCI will be beneficial for CNS repair. A critical merit of this anti-IL-6 receptor antibody is that humanized antibody to human IL-6 receptor (MRA; Atlizumab) has already been reshaped. However, there are several studies which show beneficial aspects of IL-6 signaling in the pathology of CNS trauma. Further investigation of the mechanisms how MR16-1 reduces tissue damage should be required for clinical application.

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  Systemic-onset juvenile idiopathic arthritis (JIA) is a subtype of chronic childhood arthritis of unknown cause, manifested by spiking fever, erythematous rash, arthritis, pericarditis, and hepatosplenomegaly. It has been believed a disease developed due to an excessive production of pro-inflammatory cytokines, especially interleukin (IL)-6. We organized trials of a new biologic response modifier, Toclizimuab, anti-IL-6 receptor monoclonal antibody, to patients with systemic-onset JIA. Tocilizumab directs to solely IL-6 receptor, and is called as a one-point hit drug. We successfully administered Tocilizumab to stabilize the inflammation, and inflammatory symptoms and signs of the patients were abruptly gone. Previously, corticosteroids were the only life-saving drugs, but we proved Tocilizumab will be the possible alternative for treating these children. Basic science will help us to save the children, and clinical science also will promote the basic science in turn.

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  Every clinician knows the elevation of acute phase proteins at the inflammatory status, but nobody knows the CRP or SAA induction mechanism on inflammation, in which a lot of cytokines or chemokines are activated. Induction mechanism of CRP and SAA is analyzed based on the result of the normalization of serum CRP or SAA in rheumatoid arthritis by the IL-6 blocking therapy with a humanized anti IL-6 receptor antibody. Ultimately, IL-6 is a pivotal cytokine among IL-6, IL-1 and TNF-a in induction of CRP and SAA in hepatocyte. Furthermore, activation of STAT3, a transcriptional factor under IL-6 signal transduction pathway, is critical on the expression of these mRNAs. Based on this mechanism, the depression of CRP and SAA induction could be explained by the IL-6 blockage both in vitro and in vivo. Therefore, IL-6 blocking therapy may elucidate the pathogenic significance of IL-6 in chronic inflammatory disease.

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  We herein report a case of spontaneous rupture of Achilles tendon in a 51-year-old man with refractory Reiter's syndrome. On the diagnosis in November, 2006, physical examinations and MR images showed a remarkable inflammation at the calcaneal insertion area of Achilles tendon. He required aggressive treatments with nonsteroidal anti-inflammatory drug (NSAID), oral prednisolone 30 mg daily and methotrexate (8 mg weekly) to control the disease. Two months later, the Achilles tendon ruptured at its insertion point. This ruptured lesion of Achilles tendon was an unusual site compared to previous reports. Histological findings in the ruptured lesion of Achilles tendon revealed the existence of granulomatous lesion consisted of severe infiltration of fibroblasts and vessels proliferation beside tendon. These findings suggest a prolonged inflammation. Although it is widely accepted that Reiter's syndrome is associated with enthesis, especially at the attachment of Achilles tendon to calcaneum, there have been only two reports of Achilles tendon rupture associated with Reiter's syndrome. The possible cause of the Achilles tendon rupture in this patient might be due to the weakened strength of the Achilles tendon by the prolonged and severe enthesis of Achilles tendon near the insertion lesion.

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  A 47-year-old man was admitted to our hospital in January, 2006 because of a huge cutaneous ulcer in his lower limb. He was diagnosed with polyarteritis nodosa due to the cutaneous ulcer, mononeuritis multiplex, muscular pain, elevated serum CRP level and from histological findings of a skin biopsy. He was initially treated with 60 mg/day of prednisolone, followed by 1000 mg/day of intravenous cyclophosphamide (IVCY) therapy. In June, skin grafting to the cutaneous ulcer was carried out, although the graft did not survive. He revealed therapy-resistance to high dose corticosteroid and IVCY therapy, and so was treated with intravenous high dose immunoglobulin therapy. Serum CRP level then decreased and in October skin grafting was once again undertaken, this time the graft successfully survived. In December, serum CRP level increased again and cutaneous ulcer relapsed, thus he was treated with leukocyte apheresis therapy, although it was ineffective. In February 2007, he subsequently received rituximab (375 mg/m²/week×3). Then, serum CRP level decreased rapidly, and cutaneous ulcer also improved.
  Recently the efficacy of rituximab against rheumatoid arthritis, systemic lupus erythematosus, polymyositis/dermatomyositis and ANCA-associated vasculitis has been recognized. This case suggests that rituximab is also effective against corticosteroid-resistant polyarteritis nodosa.

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