Update in juvenile myositis.

Kiran Nistala,Lucy R Wedderburn

doi:10.1097/01.bor.0000434674.62644.02

Abstract

Purpose of reviewThis update on childhood idiopathic inflammatory myopathies (IIMs) reviews recent progress in the field of translational science and clinical research over the past 12–18 months.Recent findingsSeveral new studies, including results from the international genome-wide association study, point to abnormalities of the adaptive immune system in childhood IIMs. Circulating T-follicular helper cells promote plasma cell differentiation and have been found in high levels in juvenile dermatomyositis (JDM), which may account the frequency of autoantibodies seen in this disease. One of the latest to be identified in JDM targets the protein NXP-2 and is associated with an increased risk of calcinosis in young patients. The first randomized controlled clinical trial in refractory adult and childhood IIMs was reported this year. B-cell depletion with the anti-CD20 antibody, rituximab, failed to achieve its primary end point, but patients with JDM did show good improvement in disease activity. A new international definition of disease remission in JDM has been agreed, which will aid disease assessment in future therapeutic trials.SummaryThe challenges of studying a rare disease such as JDM have been overcome by several collaborative studies and have led to significant progress in understanding the cause, treatment and prognosis of childhood IIMs.

Highlights

The childhood idiopathic inflammatory myopathies (IIMs) are a group of rare but serious multisystem diseases of which the most common is juvenile dermatomyositis (JDM), whereas juvenile polymyositis is seen in less than 5% of cases in most cohorts
As well as confirming the known association with human leukocyte antigen (HLA) region, the results have identified several genes not previously linked with IIM [1]
These results offer exciting new avenues for future research, to explore the aCentre for Rheumatology, University College London, bRheumatology Unit, UCL Institute for Child Health, London and cArthritis Research UK Centre for Adolescent Rheumatology at UCL, UCLH and GOSH, UK

Summary

INTRODUCTION

The childhood idiopathic inflammatory myopathies (IIMs) are a group of rare but serious multisystem diseases of which the most common is juvenile dermatomyositis (JDM), whereas juvenile polymyositis is seen in less than 5% of cases in most cohorts. There has been significant progress in understanding the cause of childhood IIMs, including completion of an international genomewide association study of IIM, novel studies linking JDM with environmental factors, and developments in the field of immunology. As well as confirming the known association with human leukocyte antigen (HLA) region, the results have identified several genes not previously linked with IIM [1]. These results offer exciting new avenues for future research, to explore the aCentre for Rheumatology, University College London, bRheumatology Unit, UCL Institute for Child Health, London and cArthritis Research UK Centre for Adolescent Rheumatology at UCL, UCLH and GOSH, UK.

KEY POINTS

CONCLUSION

Findings

Conflicts of interest