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29-01-2012 | Genetics | Article

Maternal microchimerism present among children with juvenile dermatomyositis

Abstract

Free abstract

MedWire News: Study findings show that children with juvenile dermatomyositis (JDM) show increased levels of maternal microchimerism (MMc), known as the presence of mother's cells, in muscle tissue compared with healthy individuals.

The findings are of importance, given the potential for maternal cells to provoke inappropriate immune responses in offspring, which could be a factor in autoimmune conditions such as JDM.

JDM is a multisystem autoimmune disease that results from inflammation of the small vessels of the muscle, skin, gastrointestinal tract, and other organs. The underlying disease mechanisms are still poorly understood, but better understanding of the etiology of the disease could lead to more targeted therapeutic strategies than broad-spectrum steroids, which can result in growth delay and osteopenia.

For the study, Kathleen Gillespie (University of Bristol, UK) and colleagues analyzed frozen muscle sections from seven boys aged 3-13 years participating in the Juvenile Dermatomyositis National Cohort Biomarker Study and Repository for Idiopathic Inflammatory Myopathies, and from four healthy controls.

At least 1000 cells from each sample underwent fluorescence in situ hybridization (FISH) and confocal imaging through each nucleus. The team also determined the nature of MMc using concomitant immunofluorescence for the lymphocytic marker CD45+.

Gillespie and team found that the frequency of MMc was significantly higher among tissue samples from children with JDM (0.42-1.14%) compared with samples from healthy controls (0.08-0.42%).

Immunofluorescence showed that although CD45+ cells were present in JDM tissue samples, no CD45+ MMc were identified.

"These data, generated using state-of-the-art confocal imaging, validate and expand previous observations of increased frequency of MMc in male JDM tissue," say the researchers in Rheumatology.

The increased frequency of MMc cells in JDM tissue samples suggests a role for MMc in the pathogenetic mechanisms underlying the condition, although this has not yet been determined.

"Further characterization is required to address the role of MMc in JDM, in particular, phenotyping muscle microchimeric cells using a wide range of immunological, muscle, and muscle stem cell markers to determine whether MMc in JDM are immune system or muscle related," conclude the authors.

By Ingrid Grasmo

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