Although there have been considerable advances in our understanding of the immunopathogenesis of the different forms of autoimmune
inflammatory myopathy, the treatment of these conditions remains largely empirical, being based upon the use of immunosuppressive and
immunomodulatory therapies which, for the most part, are non-selective in their actions.
Corticosteroids are usually effective in adult and childhood cases of
polymyositis and
dermatomyositis, but are only rarely helpful in
inclusion body myositis, which is usually also unresponsive to other forms of immunosuppressive therapy. Alternate-day
corticosteroid therapy has a role in patients with mild disease and as a means of minimizing the side-effects of
steroids. This may also be achieved by the early introduction of a second-line agent such as
methotrexate or
azathioprine, which will allow more rapid
steroid withdrawal and may also improve the chances of inducing a remission in more severe cases. In patients who fail to respond adequately to oral
corticosteroids, or who relapse after an initial response,
intravenous immunoglobulin therapy or pulse
therapy with intravenous
methylprednisolone are promising approaches which appeal as safer alternatives to cytotoxic drugs. However these forms of treatment will require further evaluation in prospective clinical trials. The same applies to
cyclosporin, which has a more selective action on T cells, and which has been reported to be effective in resistant cases of adult and juvenile
polymyositis and
dermatomyositis. In the longer term, the development of more specific forms of
immunotherapy for these
myopathies, aimed at blocking
autoantigen presentation or its interaction with T cells, awaits the identification of the target
antigens and T cells which initiate the autoimmune process.