The aim of this review was to summarize recent advances in the understanding of the clinical and autoantibody phenotypes, their associated outcomes and the pathogenesis of the juvenile idiopathic inflammatory myopathies (JIIMs). The major clinical and autoantibody phenotypes in children have many features similar to those in adults, and each has distinct demographic and clinical features and associated outcomes. The most common myositis autoantibodies in JIIM patients are anti-p155/140, anti-MJ and anti-MDA5. Higher mortality has been associated with overlap myositis as well as with the presence of anti-synthetase and anti-MDA5 autoantibodies; a chronic illness course and lipodystrophy have been associated with anti-p155/140 autoantibodies; and calcinosis has been associated with anti-MJ autoantibodies. Histologic abnormalities of JIIMs detectable on muscle biopsy have also been correlated with myositis-specific autoantibodies; for example, patients with anti-MDA5 show low levels of inflammatory infiltrate and muscle damage on biopsy. The first genome-wide association study of adult and juvenile dermatomyositis revealed three novel genetic associations, BLK, PLCL1 and CCL21 and confirmed that the human leucocyte antigen region is the primary risk region for juvenile dermatomyositis. Here, we review the well-established pathogenic processes in JIIMs, including the type 1 interferon and endoplasmic reticulum stress pathways. Several novel JIIM-associated inflammatory mediators, such as the innate immune system proteins, myeloid-related peptide 8/14, galectin 9 and eotaxin, have emerged as promising biomarkers of disease. Advances in our understanding of the phenotypes and pathophysiology of the JIIMs are leading to better tools to help clinicians stratify and treat these heterogeneous disorders.

中文翻译：

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青少年特发性炎症性肌病：发病机制，临床和自身抗体表型以及结局。

这篇综述的目的是总结对临床和自身抗体表型，它们相关的结果以及青少年特发性炎性肌病（JIIMs）的发病机理的最新进展。儿童的主要临床和自身抗体表型具有许多与成人相似的特征，并且每种特征都有不同的人口统计学和临床​​特征以及相关的结局。JIIM患者中最常见的肌炎自身抗体是抗p155 / 140，抗MJ和抗MDA5。较高的死亡率与重叠肌炎以及存在抗合成酶和抗MDA5自身抗体有关。长期病程和脂肪营养不良与抗p155 / 140自身抗体有关；钙化病与抗MJ自身抗体有关。在肌肉活检中可检测到的JIIM的组织学异常也与肌炎特异性自身抗体相关。例如，抗MDA5患者在活检时显示低水平的炎症浸润和肌肉损伤。成人和青少年皮肌炎的第一个全基因组关联研究显示了三个新的遗传关联，BLK，PLCL1和CCL21，并证实人白细胞抗原区域是青少年皮肌炎的主要危险区域。在这里，我们回顾了JIIM中公认的致病过程，包括1型干扰素和内质网应激途径。几种新的与JIIM相关的炎性介质，例如先天免疫系统蛋白，髓样相关肽8/14，半乳糖凝集素9和嗜酸性粒细胞趋化因子，已成为有希望的疾病生物标志物。