Circulating microRNAs (cimiRNAs) are a class of non-encoding RNAs found in bodily fluids such as blood, cerebrospinal fluid (CSF) and tears. CimiRNAs have been implicated as promising biomarkers for central nervous system (CNS) disorders because they are actively secreted as messengers and are profoundly involved in fine-tuning of developmental and differentiation processes. Furthermore, they are attractive biomarkers because they are extremely stable, tissue enriched and can be determined in a quantitative manner. This review aims to provide a comprehensive assessment on the current progress regarding the potential value of cimiRNAs as CNS biomarkers. Within this framework five CNS disorders are explored which share a common pathological hallmark namely cognitive impairment. The CNS disorders include Major depression disorder (MDD), Bipolar disorder (BD), Schizophrenia (SZ), Alzheimer's disease (AD) and Parkinson disease (PD). The similarities and differences between altered cimiRNAs in the different disorders are described. The miR-29 family, miR-34a-5p and miR-132-3p are discussed as common dysregulated cimiRNAs found in the CNS disorders. Furthermore, it is shown that the type of bodily fluid used for measuring cimiRNAs is important as inconsistencies in cimiRNAs expression directions are found when comparing CSF, blood cell-free and blood cell-bound samples.

中文翻译：

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循环microRNAs可作为精神疾病和神经退行性疾病的潜在生物标志物。

循环微RNA（cimiRNA）是在体液（例如血液，脑脊液（CSF）和眼泪）中发现的一类非编码RNA。CimiRNA被认为是中枢神经系统（CNS）疾病的有前途的生物标志物，因为它们作为信使而被积极分泌，并深入参与发育和分化过程的微调。此外，它们是有吸引力的生物标志物，因为它们非常稳定，组织富集并且可以定量方式进行测定。这篇综述旨在就cimiRNA作为CNS生物标志物的潜在价值提供有关当前进展的全面评估。在此框架内，探讨了五种中枢神经系统疾病，它们具有共同的病理特征，即认知障碍。中枢神经系统疾病包括重度抑郁症（MDD），躁郁症（BD），精神分裂症（SZ），阿尔茨海默氏病（AD）和帕金森氏病（PD）。描述了在不同疾病中改变的cimiRNA之间的相似性和差异。miR-29家族，miR-34a-5p和miR-132-3p被讨论为在CNS疾病中发现的常见失调的cimiRNA。此外，已表明，用于测量cimiRNA的体液类型很重要，因为在比较CSF，无血细胞和血细胞结合的样品时，发现cimiRNA的表达方向不一致。