Tratamiento de la miastenia gravis juvenil / Treatment of juvenile myasthenia gravis

La miastenia gravis juvenil es una enfermedad autoimmune poco frecuente, por lo que ha sido difícil recopilar datos de estudios controlados aleatorizados prospectivos para evaluar la eficacia y los resultados de distintos tratamientos. Si bien hay diferencias entre la miastenia gravis juvenil y la del adulto, se han utilizado los datos aportados por algunas investigaciones en adultos en el tratamiento de la miastenia gravis juvenil. Se evaluarán las distintas opciones terapéuticas, con las distintas evidencias que lo sostienen y se elaborará un algoritmo de tratamiento teniendo siempre presente que cada paciente nos ofrece distintos desafíos.

Juvenile myasthenia gravis is a rare autoimmune disease, which has made it difficult to collect data from prospective randomized controlled trials to evaluate the efficacy and results of different treatments. Although there are differences between the juvenile myasthenia gravis and that of the adult, the data provided by some researches in adults in the treatment of juvenile myasthenia gravis have been used. The different therapeutic options will be evaluated, with the different evidences that sustain it and a treatment algorithm will be elaborated keeping always in mind that each patient offers us different challenges.

Pemphigus vulgaris

Abstract: Pemphigus vulgaris is a chronic autoimmune bullous dermatosis that results from the production of autoantibodies against desmogleins 1 and 3. It is the most frequent and most severe form of pemphigus, occurring universally, usually between 40 and 60 years of age. It usually begins with blisters and erosions on the oral mucosa, followed by lesions on other mucous membranes and flaccid blisters on the skin, which can be disseminated. There is a clinical variant, pemphigus vegetans, which is characterized by the presence of vegetating lesions in the large folds of the skin. Clinical suspicion can be confirmed by cytological examination, histopathological examination, and direct and indirect immunofluorescence tests. The treatment is performed with systemic corticosteroids, and immunosuppressive drugs may be associated, among them azathioprine and mycophenolate mofetil. More severe cases may benefit from corticosteroids in the form of intravenous pulse therapy, and recent studies have shown a beneficial effect of rituximab, an anti-CD20 immunobiological drug. It is a chronic disease with mortality around 10%, and septicemia is the main cause of death. Patients need long-term and multidisciplinary follow-up.

Miopatías inflamatorias idiopáticas: una mirada actualizada al diagnóstico y el manejo / Idiopathic inflammatory myopathies: a review

Idiopathic inflammatory myopathies (IIM) are a heterogeneous group of acquired immune-mediated diseases, which typically involve the striated muscle with a variable involvement of the skin and other organs. Clinically, they are characterized by proximal muscle weakness, elevation of muscle enzymes, myopathic changes on electromyography and an abnormal muscle biopsy. The different IIM have been classified according to their distinctive histopathologic features in dermatomyositis (DM), polymyositis (PM), inclusion body myositis (IBM) and immune-mediated necrotizing myopathy (IMNM). Several myositis-specific antibodies are associated with the different phenotypes, as well as with different risk of neoplastic disease and systemic complications. The basis for the treatment of DM, PM, and IMNM is immunosuppression. For IBM there are only symptomatic treatments. Steroids, associated or not with other immunosuppressant drugs, are the first line of treatment. Biologic drugs will allow future individualized therapies. The 10-year survival of DM, PM and IMNM is 62 to 90%. The leading causes of death are neoplastic, lung and cardiac complications. IBM does not impair survival, although it affects the quality of life.

Insuficiência hepática aguda grave: diagnóstico e tratamento / Severe acute liver failure: diagnosis and treatment

A insuficiência hepática aguda grave (IHAG), embora seja uma entidade pouco frequente, possui letalidade que varia de 50% a 90 %, acometendo indivíduos, previamente hígidos, no que se concerne à função hepática. E caracterizada pela instalação súbita de perda das características fisiológicas dos hepatócitos, que costuma evoluir rapidamente, e está implicada no aparecimento da encefalopatia hepática, icterícia, hipoglicemia, alteracões da coagulação e insuficiência renal. A etiologia possui alta variabilidade geográfica. No Reino Unido e na América do Norte, a causa mais frequente é a intoxicação por paracetamol; no restante dos países predominam as hepatites virais, sobretudo a hepatite pelo vírus B. O tratamento da IHAG é feito em regime deUnidade de Terapia Intensiva, tendo no transplante hepático a modalidade terapêutica com melhores resultados. Considerando o comportamento agressivo e prognóstico reservado da IHAG, o cuidado a estes pacientes deve englobar a combinação da velha arte do cuidar hipocrático com a utilização dos recursos tecnológicos que a Medicina atual pode oferecer.

The severe acute liver failure (SALF), although a rare entity, whose mortality ranges from 50% to 90%, affects previously healthy individuals, in relation to liver function. It is characterized by a sudden loss of physiological characteristics of hepatocytes, which often change rapidly, and is implicated in the onset of hepatic encephalopathy, hypoglycemia, jaundice, changes in coagulation and renal failure. The etiology has high geographic variability. ln the UK and North America, the most frequent cause is paracetamol poisoning; in the remaining countries, the predominance is viral hepatitis, particularly by hepatitis B virus. Treatment of SALF is done on an intensive care unit and liver transplant is the treatment modality with better results. Considering the aggressive behavior and reserved prognosis of SALF, care to these patients should include a combination of the old Hippocratic art of care with the use of technological resources that current Medicine offers.

Mecanismos de acción de los fármacos inmunosupresores / Mechanisms of action of immunosuppressive drugs

Durante los últimos 50 años, muchos fármacos inmunosupresores han sido descritos, y sus mecanismos de acción se pueden dividir en: Reguladores de la expresión génica; Agentes alquilantes; Inhibidores de novo de la síntesis de purinas y pirimidinas, e Inhibidores de quinasas y fosfatasas. Los glucocorticoides ejercen su acción inmunosupresora y antiinflamatoria principalmente mediante la inhibición de la expresión de los genes de interleuquina-2 (IL-2) y otros mediadores. Los metabolitos derivados de Ciclofosfamida alquilanizan las bases de ADN y suprimen preferentemente la respuesta inmune (RI) mediada por linfocitos B (LB). Por su parte, el Metotrexato reprime las respuestas inflamatorias liberando adenosina; ésta induce la apoptosis de LT activos e inhibe la síntesis de purinas y pirimidinas. La Azatioprina inhibe varias enzimas implicadas en la síntesis de purinas, mientras que el Ácido micofenólico inhibe la inosina-monofosfato deshidrogenasa, con lo que agota los nucleótidos derivados de guanosina, induciendo la apoptosis de LT activados. Un metabolito de la Leflunomida suprime la dihidro-orotatedeshidrogenada y, consecuentemente, la síntesis de nucleótidos pirimidínicos. La Ciclosporina y el Tacrolimus inhiben la actividad de la Calcineurina, con lo que se suprime la producción de IL-2 y de otras citoquinas. Además, estos compuestos han demostrado bloquear las vías de señalización JNK y p38, activadas por el reconocimiento de antígenos en LT. Por el contrario, la Rapamicina inhibe quinasas celulares necesarias para el ciclo celular y las respuestas a IL-2; también induce la apoptosis de LT activos. Un futuro promisorio es derivado de la aplicación de fármacos inmunosupresores biológicos. El papel y mecanismos de acción de ellos serán discutidos aquí.

During the past 50 years, many immunosuppressive drugs have been described and their mechanisms of action can be organized in: Regulators of gene expression; Alkylating agents; Inhibitors of the novo purine and pyrimidine synthesis, and Inhibitors of kinases and phosphatases. Glucocorticoids exert immunosuppressive and anti-inflammatory activity mainly by inhibiting the expression of interleukin-2 (IL-2) genes and other mediators. Cyclophosphamide metabolites alkylate DNA bases and preferentially suppress immune responses mediated by B-lymphocytes. Methotrexate suppresses inflammatory responses through the release of adenosine; they suppress immune responses by inducing the apoptosis of activated T-lymphocytes and inhibit the synthesis of both purines and pyrimidines. Azathioprine metabolites inhibit several enzymes of purine synthesis. Mycophenolic acid inhibits inosine monophosphate dehydrogenase, thereby depleting guanosine nucleotides, inducing the apoptosis of activated T-lymphocytes. A Leflunomide metabolite inhibits dihydroorotate dehydrogenase, thereby suppressing pyrimidine nucleotide synthesis. Cyclosporine and Tacrolimus inhibit the phosphatase activity of Calcineurin, thereby suppressing the production of IL-2 and other cytokines. In addition, these compounds have recently been found to block the JNK and p38 signaling pathways triggered by antigen recognition in T-cells. In contrast, Rapamycin inhibits both kinases required for cell cycling and responses to IL-2; it also induces apoptosis of activated T-lymphocytes.A promising future is the application of biologic immunosuppressive drugs. We review their role and action mechanisms.

Avances en inmunosupresión en trasplante hepático / Advances in immunossuppression in liver transplantation

The history of Immunosuppresslon is a long one. From the utilization of steroids and azathloptlne In the 50's to the design of humanized molecules that specifically block cell surface receptors. Liver transplantation is one of the procedures that benefit the most with the development of new immunosuppressors and is also one of the reasons to create a new branch in research and clinical practice: transplant medicine. It also set the standards for research in the "immunologic tolerance" field. The cornerstone in the post-liver transplant stage is the utilization of calcineurin inhibitors combined with new anti-metabolites and monoclonal antibodies. All these settings conforms a promising field in the research of new and better immunosuppressing agents.

Se ha recorrido mucho camino desde el diseño de la inmunosupresión en la década de los 50's. Desde la utilización de los esteroides y la azatioprina hasta el desarrollo de moléculas humanizadas, que bloquean específicamente receptores de superficie celular para inducir tolerancia del injerto, ha transcurrido medio siglo. El trasplante hepático ha sido uno de los procedimientos más beneficiados con el desarrollo de las nuevas drogas inmunosupresoras y ha dado origen a una nueva rama de la medicina: la medicina de trasplantes. También ha sentado las bases de investigación tendiente a lograr la "tolerancia inmunológica" del órgano trasplantado. La piedra angular en la inmunosupresión postrasplante hepático es la utilización de los inhibidores de calcineurina que, en combinación con nuevos antimetabolitos y anticuerpos monoclonales, dibujan un futuro promisorio en la búsqueda de mejores agentes.