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HMGB1, a new proinflammatory molecule of interest in polymyositis and dermatomyositis patients

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Polymyositis (PM) and dermatomyositis (DM) are chronic inflammatory muscle disorders of unknown origin. The ubiquitously expressed nuclear protein high mobility group box chromosomal protein 1 (H MGB1) will, when released extracellularly, act as a potent proinflammatory molecule.


To investigate H MGB1 expression in muscle tissue from PM and DM patients with and without inflammatory infiltrates present in their muscle biopsy.


Muscle biopsy specimens from 10 patients (6 PM, 4 DM) with and 14 patients (8 PM, 6 DM) without inflammatory cell infiltrates and 8 healthy controls were investigated. H MGB1 expression was studied by immunohistochemical staining.


Patients with inflammatory cell infiltrates show H MGB1 staining mainly with a cytoplasmic localization in vascular endothelial cells, infiltrating rounded mononuclear cells of macrophage-like morphology for all patients and in muscle fibres in 6 of 10 patients. In patients without inflammatory infiltrates, H MGB1 was detected in 3 of 14 patients, all with DM, in endothelial cells with a cytoplasmic manner, there was no H MGB1 expression in the muscle fibres. No cytoplasmic or nuclear H MGB1 expression was found in the muscle tissue specimens from healthy controls.


H MGB1 was detected in muscle biopsies from PM and DM patients with inflammatory cell infiltrates. H MGB1 could play a role in maintaining the chronic inflammation. The major cell source of H MGB1 production in myositis seems to be the mononuclear inflammatory cells. H MGB1 could be a molecule of potential interest for new targeted therapy in myositis.

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  • Muscle Biopsy
  • Myositis
  • Dermatomyositis
  • Inflammatory Cell Infiltrate
  • Proinflammatory Molecule