Neuropediatrics 2013; 44 - FV16_05
DOI: 10.1055/s-0033-1337749

Molecular mechanisms of juvenile dermatomyositis

C Preusse 1, B Schoser 2, HH Goebel 1, W Stenzel 1, U Schara 3
  • 1Institut fuer Neuropathologie, Berlin, Germany
  • 2Friedrich Baur Institut, Muenchen, Germany
  • 3Neuropaediatrie, Essen, Germany

Aims: The most common form of myopathy in children is juvenile dermatomyositis (jDM). jDM is defined as dermatomyositis with an age of onset below 18 years, and shows an annual incidence of 2 to 3 per million children.

In addition to the classical symptoms of proximal symmetric muscle weakness further symptoms such as arthralgia, fatigue, and dysphagia can occur in DM. The specific involvement of the skin is a discriminating factor and can manifest as heliotrope rash of face and décolleté, Gottron papules and periungual telangiectasias. Elevated CK levels, as well as measurement of autoimmune antibodies can support the diagnosis.

The etiology of jDM is unknown and the underlying immune mechanism poorly understood which is why current studies address the question of environmental triggers, genetic predisposition, or maternal microchimerism. Furthermore aspects of the immune response, such as the role of DCs, are intensively studied.

Methods: On muscle biopsies immune cells can be found in perifascicular infiltrates and apart from the well-studied T and B cells one can find a considerable amount of macrophages, which have not been further characterized so far. Additionally molecular signs of hypoxia can be detected focally.

We address the question of a possible link between the appearance of inflammatory infiltrates and hypoxia related factors, such as HIF-1a, VEGF or STAT3 in jDM and aDM. Therefore, we studied muscle biopsies from 10 patients with adult and 12 patients with jDM in comparison to normal controls by diverse histological stainings, immunofluorescence, and quantitative real-time polymerase chain reaction.

Results: There are no obvious differences in Th1 and Th2 responses while Th17 immunity is more pronounced in jDM.

In addition, hypoxia related factors are expressed at significantly higher levels in jDM then in adult DM.

Conclusion: Several similarities between dermatomyositis during childhood and adulthood have been detected, however striking differences concerning Th-17 immunity and hypoxia-related factors are detectable in both groups.