Disease chronicity in juvenile dermatomyositis (JDM): Epigenetic clues

描述（由申请人提供）：幼年型皮肌炎（JDM）是最常见的儿科炎性肌病，发生于幼儿（症状发作时的平均年龄为6.7岁;女孩：男孩比例=2.3：1），死亡率为1-2%，继发于营养不良性钙化和继发性挛缩的发病率增加。儿童的生活质量下降，但慢性炎症的作用尚未得到评估。未治疗炎症的持续时间是一个关键因素：超过两个月的未治疗症状与慢性皮疹和基因表达谱研究中血管重塑基因的上调有关。慢性皮疹还与甲襞毛细血管末排环的丢失、药物吸收受损有关，并且作为年轻人，患者似乎容易过早发生心血管损伤。对内皮细胞的损伤由IFN- 1和TNF-1介导，并且这两种细胞因子在JDM血清和组织中增加。增加的TNF-1水平与TNF-1-308启动子区的多态性相关。我们还发现，在JDM儿童中，OPN和TNF-1启动子区域之间存在复杂的基因-基因-性别相互作用。这定义了高血清IFN-1亚组内的JDM，这可能有助于增加发病率的JDM的女孩。在治疗JDM时，公认的治疗指南是肌肉酶的血清水平，其迅速恢复正常，留下空白。在JDM中提供有效治疗的主要障碍是缺乏炎症生物标志物以及疾病严重程度的预后指标。本研究的目的是确定表观遗传机制-全球甲基化和miRNA表达的差异-在剖析慢性炎症和性别对JDM微血管病变的影响方面至关重要。我们假设：1）慢性JDM中生活质量的降低与虚弱的相关性小于与慢性皮肤受累的相关性，与长期未治疗的疾病相关，以及2）鉴定JDM肌肉和内皮前体细胞（EPC）中的表观遗传调节机制和特异性miRNA将揭示新的发病机制，其将指导更有效治疗的开发。为了实现这一目标，将比较未经治疗的JDM儿童的良好表征的肌肉活检：1）短持续时间（< 2个月）与长持续时间（2个月），2）年龄匹配的男孩与女孩相比，疾病持续时间也匹配。在特异性目标1中，全球甲基化研究，将JDM与对照进行比较，将识别低甲基化区域，如WT 1和HOX基因，并测试它们与miRNA表达强度水平的关系。具体目标2将确定miRNA表达水平与儿童生活质量、疾病活动评分（DAS）及其TNF-1-308 AA/AG vs GG状态的相关性。例如，我们发现，在病程短的JDM GG中上调的miR-34 a调节了转录激活因子Bcl 12的表达，这在凋亡途径中很重要。在特定目标3中，将从JDM和年龄-性别匹配对照的血液中分离内皮前体细胞（EPC），并表征其表观遗传特征。此外，他们的功能将在体外进行研究，并与儿童的甲襞毛细血管末行环路的结构损失的程度进行比较。然后在功能获得/丧失实验中检测分离的EPC，目的是恢复正常状态。预计从拟议工作中获得的科学知识将为我们未来的决策提供信息，并导致更合理和有效的干预措施。 公共卫生相关性：幼年型皮肌炎（JDM）是一种儿童自身免疫性疾病，其中小血管受损;慢性炎症与持续性皮疹、活动范围丧失、钙化沉积甚至执行爬楼梯或举物体等任务的能力有关，因此影响儿童的生活质量。在本研究中，患有JDM的儿童的生活质量将被确定，并与他们的表观遗传状态-表型遗传变化相关。（个体的可观察特征）由基因和环境决定-通过测试未经治疗的JDM儿童的诊断性肌肉活检，（>2个月）与短病程（d2个月）相比，男孩与女孩（病程匹配）和年龄、性别匹配的健康对照相比。目标是确定特定的标记物，如microRNA，或“开启基因”，这可能是修复血管损伤的关键，并确定更有效的医疗干预措施。

DESCRIPTION (provided by applicant): Juvenile dermatomyositis (JDM) is the most common pediatric inflammatory myopathy and occurs in young children (mean age at onset of symptoms, 6.7 years; girl: boy ratio=2.3:1) with 1-2% mortality and increased morbidity secondary to dystrophic calcifications and secondary contractures. The children have a decreased quality of life, but the role of chronic inflammation has not been evaluated. The duration of time of the untreated inflammation is a critical factor: untreated symptoms of greater than two months are associated with a chronic rash and upregulation of vascular remodeling genes on gene expression profile studies. The chronic rash is also associated with loss of nailfold capillary end row loops, impaired absorption of medications, and as young adults, the patients appear prone to premature cardiovascular damage. Damage to endothelial cells is mediated by IFN- 1 and TNF-1, and both cytokines are increased in JDM sera and tissue. Increased TNF-1 levels are associated with a polymorphism in the promoter region of TNF-1-308. We also found a complex gene-gene-gender interaction between the OPN and TNF-1 promoter regions in JDM children. This defined a high serum IFN-1 subgroup within JDM, which may contribute to the increased incidence of JDM in girls. In treating JDM, the accepted guide to therapy is serum levels of muscle enzymes, which normalize rapidly, leaving a void. A major barrier to providing effective therapy in JDM is the lack of biomarkers of inflammation as well as prognostic indicators of disease severity. The purpose of this study is to identify epigenetic mechanisms - differences in global methylation and miRNA expression - critical in dissecting the impact of chronic inflammation and gender on JDM microvasculopathy. We hypothesize: 1) Decreased quality of life in chronic JDM is related less to weakness than to the chronic skin involvement, associated with long untreated disease, and, 2) identification of epigenetic regulatory mechanisms and specific miRNAs in JDM muscle and in endothelial precursor cells (EPCs) will disclose novel pathogenetic mechanisms that will guide the development of more effective therapy. To accomplish this goal, well-characterized muscle biopsies from untreated children with JDM will be compared: 1) short duration (< 2 month) vs. long (e 2 months) duration, and 2) age-matched boys compared with girls, also matched for disease duration. In Specific Aim 1, global methylation studies, comparing JDM with controls will identify areas of hypomethylation, such as the WT1 and HOX genes, and test their relation to intensity levels of miRNA expression. Specific Aim 2 will determine the association of levels of miRNA expression with the child's quality of life, disease activity scores (DAS), and their TNF-1-308 AA/AG vs GG status. For example, we found that miR-34a, upregulated in JDM GG with short disease duration modulates the expression of the transcriptional activator Bcl12, important in the apoptotic pathway. In Specific Aim 3, endothelial precursor cells (EPCs) will be isolated from the blood of JDM and age-gender matched controls and their epigenetic features characterized. In addition, their function will be studied in vitro and compared with the extent of the child's structural loss of nailfold capillary end row loops. The isolated EPCs will then be tested in gain/loss of function experiments, with the goal of restoration of normality. It is anticipated that the scientific knowledge gained from the proposed work will inform our future decision making and lead to more rational and effective interventions. PUBLIC HEALTH RELEVANCE: Juvenile dermatomyositis (JDM) is an autoimmune disease of children, in which there is damage to the small blood vessels; chronic inflammation is associated with persistent rash, loss of range of motion, deposits of calcifications and even the ability to perform tasks like climbing stairs or lifting objects and, therefore, affects the child's quality of life. In this study, the quality of life of the children with JDM will be determined and correlated with their epigenetic status - inherited changes in phenotype (individual's observable traits) determined by genes and the environment - by testing diagnostic muscle biopsies from untreated children with JDM with long (>2 months) compared with short disease duration (d 2 months) and boys compared with girls (matched for disease duration) and age-, gender-matched healthy controls. The goal is to identify specific markers, like microRNA, or "turned on genes" that may be key to repair the vascular damage and to identify more effective medical interventions.