Inflammatory Myopathy

Immunotherapies for Immune-Mediated Myopathies: A Current Perspective

Until recently, the treatment of immune-mediated inflammatory myopathies has largely been empirical with glucocorticoids, steroid-sparing immunosuppressive drugs, and intravenous immunoglobulin. However, a proportion of patients are only partially responsive to these therapies, and there has been a need to consider alternative treatment approaches. In particular, patients with inclusion body myositis are resistant to conventional immunotherapies or show only a transient response, and remain a major challenge. With increasing recognition of the different subtypes of immune-mediated inflammatory myopathies, and improved understanding of their pathogenesis, more targeted treatments are now being trialled. The overall approach to treatment, and novel therapies targeting B cells, T cells, and specific cytokines are discussed in this review.

How citation distortions create unfounded authority: analysis of a citation network

OBJECTIVE

To understand belief in a specific scientific claim by studying the pattern of citations among papers stating it.

DESIGN

A complete citation network was constructed from all PubMed indexed English literature papers addressing the belief that beta amyloid, a protein accumulated in the brain in Alzheimer's disease, is produced by and injures skeletal muscle of patients with inclusion body myositis. Social network theory and graph theory were used to analyse this network.

MAIN OUTCOME MEASURES

Citation bias, amplification, and invention, and their effects on determining authority.

RESULTS

The network contained 242 papers and 675 citations addressing the belief, with 220,553 citation paths supporting it. Unfounded authority was established by citation bias against papers that refuted or weakened the belief; amplification, the marked expansion of the belief system by papers presenting no data addressing it; and forms of invention such as the conversion of hypothesis into fact through citation alone. Extension of this network into text within grants funded by the National Institutes of Health and obtained through the Freedom of Information Act showed the same phenomena present and sometimes used to justify requests for funding.

CONCLUSION

Citation is both an impartial scholarly method and a powerful form of social communication. Through distortions in its social use that include bias, amplification, and invention, citation can be used to generate information cascades resulting in unfounded authority of claims. Construction and analysis of a claim specific citation network may clarify the nature of a published belief system and expose distorted methods of social citation.

Current therapies for neuromuscular manifestations of paraneoplastic syndromes

The neuromuscular manifestations of paraneoplastic disorders result in diverse syndromes that may also occur in patients without cancer. In general, treatment of these disorders is the same whether or not there is an underlying malignancy. However, when the disorder is believed to be paraneoplastic, the main concern should be prompt detection and treatment of the tumor, as this has been shown to offer the best chance for neurologic stabilization or improvement. The paraneoplastic neuromuscular disorders can be divided into two main categories: those that are directly mediated by antibodies and those that are believed to result from other immune-mediated mechanisms, including cytotoxic T-cell responses with or without association with specific antibodies. For disorders in which the antibodies are pathogenic, therapy is aimed at removing the antibodies. For the other disorders, adjuvant therapies are for the most part empiric and include a variety of immunosuppressant and immunomodulatory agents.

A method for extracting muscle information from serum creatine kinase measurements – Its potential value in the monitoring and management of inflammatory muscle disease

A major problem in treating inflammatory myopathies is the very limited information available about the processes taking place. For instance serum creatine kinase levels are often dismissed as a means of gaining an understanding of what is happening or a means of monitoring a patient. This paper shall show how serum creatine kinase levels may be used to explore the processes taking place that create muscle inflammation. This is achieved by a detailed longitudinal study. Firstly, considerable laboratory data is gathered such as serum creatine kinase levels and blood pressure information. Secondly, the data is quantified using a scientific model. We shall illustrate the approach through an extensive nine-year study of a particular polymyositis patient. We identify three basic processes that may contribute to muscle inflammation and show how they may be interpreted from specific patient data. Furthermore, details are given for controlling and monitoring the disease to maximise the reduction in the muscle attack while reducing significantly the muscle inflammation and keeping the drug concentration at a minimum to ensure minimum side-effects and how to identify and handle drug-drug, drug-natural product and adverse drug interactions. Examples are given for a natural product, azathioprine and trandolapril.

Inflammatory myopathies: clinical, diagnostic and therapeutic aspects

The three major forms of immune-mediated inflammatory myopathy are dermatomyositis (DM), polymyositis (PM), and inclusion-body myositis (IBM). They each have distinctive clinical and histopathologic features that allow the clinician to reach a specific diagnosis in most cases. Magnetic resonance imaging is sometimes helpful, particularly if the diagnosis of IBM is suspected but has not been formally evaluated. Myositis-specific antibodies are not helpful diagnostically but may be of prognostic value; most antibodies have low sensitivity. Muscle biopsy is mandatory to confirm the diagnosis of an inflammatory myopathy and to allow unusual varieties such as eosinophilic, granulomatous, and parasitic myositis, and macrophagic myofasciitis, to be recognized. The treatment of the inflammatory myopathies remains largely empirical and relies upon the use of corticosteroids, immunosuppressive agents, and intravenous immunoglobulin, all of which have nonselective effects on the immune system. Further controlled clinical trials are required to evaluate the relative efficacy of the available therapeutic modalities particularly in combinations, and of newer immunosuppressive agents (mycophenolate mofetil and tacrolimus) and cytokine-based therapies for the treatment of resistant cases of DM, PM, and IBM. Improved understanding of the molecular mechanisms of muscle injury in the inflammatory myopathies should lead to the development of more specific forms of immunotherapy for these conditions.

Inflammatory myopathies: how to treat the difficult cases

The initial approach to the treatment of patients with inflammatory myopathy is critical in determining the subsequent course and outcome. Prolonged administration of high doses of corticosteroids should be avoided and a second-line agent such as methotrexate or azathioprine should be introduced earlier rather than later. Intravenous immunoglobulin therapy has an important place if the myositis remains active, particularly in patients with dermatomyositis, and is the treatment of choice in patients with immunodeficiency who are not controlled by corticosteroids. In more resistant cases of polymyositis or dermatomyositis it may be necessary to use cyclophosphamide, cyclosporin or the promising newer immunosuppressive agents mycophenolate mofetil or tacrolimus to achieve disease control. The treatment of inclusion body myositis remains unsatisfactory but a trial of prednisolone and methotrexate is warranted in selected patients.