There are over 80 different kinds of autoimmune disease, most of which are currently incurable. Ongoing research has led to advances in their treatment, however in the case of Juvenile Dermatomyositis (JDM), as with many rare diseases, much is still unknown. JDM predominantly affects the skin and muscles of children, and is a potentially life-threatening disease. Lucy Wedderburn and Kiran Nistala, from University College London’s Institute of Child Health, UK, and colleagues analysed blood serum and muscle biopsies to identify a potential biomarker for disease activity. Nistala told Biome more about these results, published in a study in Arthritis Research & Therapy, and what impact these insights could have for treatment.
You belong to the UK Juvenile Dermatomyositis Research Group (JDRG). What is the JDRG and what do you hope to achieve as a part of it?
The JDRG is a national group of paediatric rheumatologists and scientists who are interested in improving the understanding and clinical care of patients with JDM, by sharing information on their patients, promoting research and creating the largest cohort study of JDM patients in Europe.
What is Juvenile Dermatomyositis (JDM) and how rare is it?
Juvenile Dermatomyositis (JDM) is an autoimmune disease affecting approximately 3 children in every million per year. Muscles weakness and skin rash are the main symptoms of JDM and it affects every child differently with some children experiencing a mild form of the disease while others display a more severe disease progression.
What challenges exist in diagnosing and treating JDM?
As a rare disease, it is difficult to collect sufficient numbers of JDM patients to test new diagnostic criteria and plan randomised controlled trials (RCT) of new drugs. At present most treatments are based on expert opinion rather than trial data. On a more positive note, there was a recent large RCT of rituximab (anti CD20 monoclonal antibody) in adult and juvenile dermatomyositis, and international groups, such as the JDRG, are working on updating the diagnostic criteria originally published in 1975.
What did your study set out to investigate?
We wanted to find out if myeloid related peptide (MRP) would be an accurate biomarker for disease activity in JDM, and if so, what might be the mechanism that underlies this observation.
What most excited you about your findings?
We were very pleased to see that serum MRP did correlate with other measures of disease activity in JDM. MRP is heat stable and easy measured by ELISA which makes it an ideal candidate for a biomarker in clinical practice.
What impact would a specific biomarker have on the day-to-day management of this condition?
One of the major challenges of JDM is trying to distinguish muscle weakness caused by active inflammation from muscle damage caused by corticosteroids or deconditioning. Having a specific biomarker for disease activity, would allows us to limit treatment escalation to those patients with real disease flares, and in this way, minimise iatrogenic harm from our treatments.
Your study defines a pathway by which macrophages ‘crosstalk’ and perpetuate inflammtatory myocytis. Do you think this is specific to JDM?
No, this is unlikely to be specific to JDM. Interestingly, muscle inflammation is also a feature of the muscular dystrophies and it is possible that MRP contributes to pathology in these disorders.
What’s next for your research?
We are carrying out a wider study to identify prognostic factors in JDM, by examining serological markers of inflammation (such as MRP), muscle biopsy results and autoantibody status, to identify those patients at risk of poor long term outcomes. In this way, we hope to target therapy to the correct patients, saving aggressive treatments for those patients who really need it.