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Immunopathogenesis of inflammatory myopathies
1Medical Neurology Branch, NINDS, NIH, Bethesda, MD 20892-1382, USA.
Annals of Neurology
|May 1, 1995
Summary
Polymyositis and dermatomyositis involve immune responses, with complement system activation in dermatomyositis and T-cell attack in polymyositis. Intravenous immunoglobulin (IVIg) shows promise for treatment-resistant cases.
Area of Science:
- Immunology
- Neurology
- Rheumatology
Background:
- Polymyositis (PM) and dermatomyositis (DM) are immune-mediated myopathies.
- Pathogenesis involves distinct immune mechanisms in PM and DM.
Purpose of the Study:
- To elucidate the immune-mediated mechanisms in polymyositis and dermatomyositis.
- To review current and potential therapeutic strategies for inflammatory myopathies.
Main Methods:
- Analysis of serum complement fragments (C3b, C4b, C5b-9) in DM patients.
- Investigation of T-cell receptor patterns in PM endomysial infiltrates.
- Assessment of adhesion molecule (ICAM-1, VCAM-1) expression in PM and DM.
Main Results:
- DM pathogenesis involves complement activation and deposition of membranolytic attack complex (MAC) on capillaries.
- PM pathogenesis involves CD8+ cytotoxic T cells targeting muscle antigens.
- Upregulation of ICAM-1 and VCAM-1 facilitates lymphocyte migration in both conditions.
- Retroviruses HIV and HTLV-1 are implicated in triggering PM.
Conclusions:
- Distinct immune pathways drive PM and DM pathogenesis.
- Current treatments for inflammatory myopathies are empirical, with steroids offering partial benefit.
- Intravenous immunoglobulin (IVIg) is a promising therapy for refractory DM and is under investigation for PM and inclusion body myositis (IBM).