Autoantibodies in adult patients with idiopathic inflammatory myopathies in Buenos Aires

The idiopathic inflammatory myopathies(IIM) are a heterogeneous group of diseases of the skeletal muscle. On the basis of clinical, serologic and histological differences, they are classified in dermatomyositis (DM), polymyositis (PM), inclusion body myositis and immunomediated necrotizing myopathy. Autoantibodies directed against nuclear and cytoplasmic antigens are present with variable frequencies among studies. Myositis-specific antibodies (MSAs) are useful in IIM because they contribute to the diagnosis, help to identify different clinical subsets, and have prognostic value. This study aimed to explore the frequency of autoantibodies, especially MSAs, and their relationship with clinical features in adult patients with DM, PM and overlap syndrome. Medical records were reviewed. Myositis-associated antibodies (non-specific) and MSAs (anti Jo-1, PL-7, PL-12, Mi-2 and SRP) were measured using commercial kits. Twelve patients had MSAs, an overall frequency similar to those of international series, but PL-12 and Mi-2 were more frequent than Jo-1, which is the most frequently observed elsewhere. All five patients with Mi-2 had classical DM with a favorable response to treatment. Interstitial pneumonia (n: 4) and/or treatment-refractory disease (n: 3) were found in the presence of anti-PL-12, alone or associated with anti-SRP and/or Jo-1. In conclusion, the coexistence of AEM, a rare finding, was found in three patients. The presence of MSAs aided to the diagnosis of IIM, in particular in those patients without available or conclusive biopsy results.

Las miopatías inflamatorias idiopáticas (MII) comprenden un grupo heterogéneo de enfermedades adquiridas del músculo esquelético. Según sus características clínicas, serológicas e histológicas se las clasifica en dermatomiositis (DM), polimiositis (PM), miopatía necrotizante autoinmune y miositis por cuerpos de inclusión. Los anticuerpos específicos de miositis (AEMs) contribuyen al diagnóstico, permiten distinguir formas clínicas y tienen valor pronóstico. Con el objetivo de explorar la frecuencia de autoanticuerpos, en particular AEMs, y su relación con las características clínicas de las MII del adulto, se revisaron las historias clínicas de 25 pacientes con DM, PM y síndromes de superposición, asistidos en nuestro centro entre 1999 y 2013. La presencia de autoanticuerpos asociados a miositis (no específicos) y AEMs (anti Jo-1, PL-7, PL-12, Mi-2, SRP) se investigó utilizando kits comerciales. Doce pacientes presentaron AEMs, frecuencia global similar a la encontrada en series internacionales, pero a diferencia de lo observado en otros países, anti-PL-12 y anti-Mi-2 fueron más frecuentes que anti-Jo-1. Los cinco pacientes con anti-Mi-2 tuvieron DM clásica y buena evolución clínica. Anti-PL-12, ya sea solo o asociado a anti-SRP y/o anti-Jo-1, estuvo presente en pacientes con neumonía intersticial (n:4) y/o enfermedad refractaria al tratamiento (n: 3). En conclusión, la coexistencia de AEM, hallazgo raro, se encontró en tres pacientes. La presencia de AEMSs contribuyó al diagnóstico de MII, en particular en aquellos casos sin resultados concluyentes de biopsia de músculo.

The research of myosin-binding protein C in duced autoimmune myositis model / 中华风湿病学杂志

Objective To establish a new murine model of experimental autoimmune myositis by immunizing with MYBPC2 protein. Methods The purified Myosin-binding protein C, fast type (MYBPC2) was emulsified with complete Freundˊs adjuvant, then C57BL/6 mice were immunized by multi-point subcutaneous injection (0, 7 days), and intraperitoneal injection of pertussis toxin 2 μg simultaneously. The pathological changes of mice with different immunizing dose at the preconceived time were ex-plored. Mean-while, mice were immunized with 600 μg each time, and the muscle endurance was tested on the 21th day. The expression of major histocompatibility complex (MHC) class-Ⅰ and the surface biomarkers of the inflammatory cells in muscle tissues were observed. Mann-Whitney U test was used for statistical analysis. Results ① With the increase of immunizing dosage, muscle damage and inflammation tended to be more serious. On the 21th and 28th day, muscle lesions were most significant. Muscle fiber degeneration and necrosis and inflammatory cell infiltration could be seen in the experimental group. ② Compared with the control group, muscle endurance of mice in the experimental group decreased significantly [(6.1 ±1.3) min versus (9.2±1.6) min, U=2.00, P=0.017]. The MHC class-Ⅰ on the muscle fiber surface of the experimental group was positive, scattered infiltration of CD4 +, CD8+ T ly-mphocytes and CD68 + macrophages between muscle fibers and around the vascular areas could be observed, and CD20+B lymphocytes mainly distributed in the area around the blood vessels, nevertheless rarely seen between muscle fibers. Conclusion Exper-imental autoimmune myositis models of mice have been successfully induced by immunizing with MYBPC2 in China for the first time, and similar clinical and pathological features of human polymyositis could be observed. This new model can be used for studying the pathogenesis of autoimmune myositis.

Dermatomiosite na infância / Juvenile dermatomyositis

A dermatomiosite juvenil é uma doença autoimune que acomete crianças e adolescentes entre 2 e 17 anos de idade, com média de 7 anos ao diagnóstico. É caracterizada por vasculopatia sistêmica e suas manifestações principais são fraqueza muscular proximal simétrica, elevação de enzimas musculares séricas e lesões cutâneas, sendo que o heliótropo e as pápulas de Gottron são patognomônicas. Sua identificação precoce e instituição rápida de tratamento adequado podem prevenir o aparecimento de calcinose e possibilitam melhor prognóstico e qualidade de vida ao paciente. Embora a base medicamentosa da terapia seja o uso de glicocorticoide, o metotrexato, a ciclosporina, a azatioprina e a ciclofosfamida, dependendo da gravidade, são os imunossupressores mais frequentemente utilizados. Imunoglobulina endovenosa pode ser útil nos casos graves e atualmente o uso de imunobiológicos representa uma nova perspectiva para os casos refratários.

Dermatomiosite juvenil: revisão e atualização em patogênese e tratamento / Juvenile dermatomyositis: review and update of the pathogenesis and treatment

A dermatomiosite juvenil (DMJ) é uma doença autoimune caracterizada por vasculopatia sistêmica. Manifestações principais da DMJ incluem fraqueza muscular proximal simétrica, elevação de enzimas musculares séricas e lesões cutâneas, dentre as quais o heliotropo e as pápulas de Gottron são patognomônicas. Reconhecimento precoce e instituição rápida de terapia adequada permitem melhorar o prognóstico da doença e evitar o aparecimento de calcinose. Embora a base do tratamento seja o glicocorticoide, os imunossupressores mais frequentemente associados são metotrexato, ciclosporina, azatioprina e ciclofosfamida, dependendo da gravidade da DMJ. Atualmente investiga-se a utilidade dos imunobiológicos nos casos refratários, mas os resultados são controversos ou pouco expressivos. Pretende-se neste artigo fazer uma revisão sobre DMJ, com ênfase em recentes atualizações na sua patogênese e tratamento.

Juvenile dermatomyositis (JDM) is an autoimmune disease characterized by systemic vasculopathy. Its main manifestations include symmetrical proximal muscle weakness, elevated serum muscle enzymes and cutaneous lesions, among which the heliotrope and Gottron's papules are pathognomonic. Early recognition and prompt therapy allow better prognosis and prevent the development of calcinosis. Although the treatment is based on glucocorticoids, the more commonly associated immunosuppressors include methotrexate, azathioprine, cyclosporine, and cyclophosphamide, depending on the severity of disease. The use of immunobiologicals for refractory cases remains under investigation, but the results are controversial or inexpressive. In this review, we highlight recent updates on the pathogenesis and treatment of JDM.