Effect of endurance exercise on microRNAs in myositis skeletal muscle—A randomized controlled study

ObjectiveTo identify changes in skeletal muscle microRNA expression after endurance exercise and associate the identified microRNAs with mRNA and protein expression to disease-specific pathways in polymyositis (PM) and dermatomyositis (DM) patients.MethodsFollowing a parallel clinical trial design, patients with probable PM or DM, exercising less than once a week, and on stable medication for at least one month were randomized into two groups at Karolinska University Hospital: a 12-week endurance exercise group (n = 12) or a non-exercised control group (n = 11). Using an Affymetrix microarray, microRNA expression was determined in paired muscle biopsies taken before and after the exercise intervention from 3 patients in each group. Ingenuity pathway analysis with a microRNA target filter was used to identify microRNA transcript targets. These targets were investigated at the mRNA (microarray) and protein (mass spectrometry) levels in patients.ResultsEndurance exercise altered 39 microRNAs. The microRNAs with increased expression were predicted to target transcripts involved in inflammatory processes, metabolism, and muscle atrophy. Further, these target transcripts had an associated decrease in mRNA expression in exercised patients. In particular, a decrease in the NF-κB regulator IKBKB was associated with an increase in its target microRNA (miR-196b). At the protein level, there was an increase in mitochondrial proteins (AK3, HIBADH), which were associated with a decrease in microRNAs that were predicted to regulate their expression.ConclusionImprovement in disease phenotype after exercise is associated with increasing microRNAs that target and downregulate immune processes at the transcript level, as well as decreasing microRNAs that target and upregulate mitochondrial content at the protein level. Therefore, microRNAs may improve disease by decreasing immune responses and increasing mitochondrial biogenesis.Trial registrationClinicalTrials.gov NCT01184625研究目的：明确耐力运动后骨骼肌微小RNA（microRNA）的表达变化，并将鉴定出的微小RNA与多发性肌炎（polymyositis, PM）和皮肌炎（dermatomyositis, DM）患者的疾病特异性通路相关的mRNA及蛋白质表达进行关联分析。 研究方法：本研究采用平行临床试验设计，于卡罗林斯卡大学医院招募疑似PM或DM、每周运动频次不足1次且接受至少1个月稳定药物治疗的患者，将其随机分为两组：12周耐力运动组（n=12）与非运动对照组（n=11）。针对两组各3名患者，采集其运动干预前后的配对肌肉活检标本，采用Affymetrix基因芯片（Affymetrix microarray）检测其中的微小RNA表达水平。通过搭载微小RNA靶点筛选模块的Ingenuity通路分析（Ingenuity pathway analysis）鉴定微小RNA的转录靶点，并在患者样本中分别通过基因芯片检测mRNA水平、质谱分析法（mass spectrometry）检测蛋白质水平对上述靶点进行验证。 研究结果：耐力运动可使39种微小RNA的表达发生显著改变。其中表达上调的微小RNA被预测可靶向参与炎症反应、代谢调控及肌肉萎缩过程的转录本；进一步分析显示，这些靶转录本在运动干预患者中的mRNA表达水平显著下调。具体而言，核因子κB调控蛋白IKBKB的表达下调与其靶微小RNA miR-196b的表达上调呈显著关联。在蛋白质水平上，线粒体蛋白AK3、HIBADH的表达水平上调，而被预测可调控其表达的微小RNA水平则显著下降。 研究结论：运动后疾病表型的改善与两类微小RNA的表达变化密切相关：一类为表达上调的微小RNA，可在转录水平下调免疫应答过程；另一类为表达下调的微小RNA，可在蛋白质水平上调线粒体含量。由此可见，微小RNA或可通过抑制免疫应答、促进线粒体生物发生来改善疾病进程。 试验注册：ClinicalTrials.gov NCT01184625