Micro-RNA Profiling in Human Serum Reveals Compartment-Specific Roles of miR-571 and miR-652 in Liver Cirrhosis

Background and AimsMicro-RNAs (miRNAs) have recently emerged as crucial modulators of molecular processes involved in chronic liver diseases. The few miRNAs with previously proposed roles in liver cirrhosis were identified in screening approaches on liver parenchyma, mostly in rodent models. Therefore, in the present study we performed a systematic screening approach in order to identify miRNAs with altered levels in the serum of patients with chronic liver disease and liver cirrhosis.
MethodsWe performed a systematic, array-based miRNA expression analysis on serum samples from patients with liver cirrhosis. In functional experiments we evaluated the relationship between alterations of miRNA serum levels and their role in distinct cellular compartments involved in hepatic cirrhosis.
ResultsThe array analysis and the subsequent confirmation by qPCR in a larger patient cohort identified significant alterations in serum levels of miR-513-3p, miR-571 and miR-652, three previously uncharacterized miRNAs, in patients with alcoholic or hepatitis C induced liver cirrhosis. Of these, miR-571 serum levels closely correlated with disease stages, thus revealing potential as a novel biomarker for hepatic cirrhosis. Further analysis revealed that up-regulation of miR-571 in serum reflected a concordant regulation in cirrhotic liver tissue. In isolated primary human liver cells, miR-571 was up-regulated in human hepatocytes and hepatic stellate cells in response to the pro-fibrogenic cytokine TGF-β. In contrast, alterations in serum levels of miR-652 were stage-independent, reflecting a concordant down-regulation of this miRNA in circulating monocytes of patients with liver cirrhosis, which was inducible by proinflammatory stimuli like bacterial lipopolysaccharide.
ConclusionAlterations of miR571 and miR-652 serum levels in patients with chronic liver disease reflect their putative roles in the mediation of fibrogenic and inflammatory processes in distinct cellular compartments involved in the pathogenesis of liver cirrhosis.

研究背景与目的：微小RNA（Micro-RNAs, miRNAs）近年来被证实是慢性肝病相关分子进程的关键调控因子。此前被认为与肝硬化相关的少数miRNAs，多是通过对肝实质组织的筛选实验（多以啮齿类动物为模型）鉴定得到的。因此，本研究采用系统性筛选策略，旨在鉴定慢性肝病及肝硬化患者血清中表达水平异常的miRNAs。
研究方法：我们针对肝硬化患者的血清样本开展了基于芯片的系统性miRNA表达谱分析。同时通过功能实验，探究了血清miRNA水平异常与它们在肝硬化相关不同细胞亚群中的功能之间的关联。
研究结果：芯片分析及后续在更大患者队列中采用实时定量聚合酶链反应（quantitative real-time polymerase chain reaction, qPCR）进行的验证实验，鉴定出酒精性或丙型肝炎病毒性肝硬化患者血清中miR-513-3p、miR-571及miR-652这三种此前未被表征的miRNAs的水平存在显著异常。其中，miR-571的血清水平与疾病分期密切相关，有望成为肝硬化的新型生物标志物。进一步分析显示，血清中miR-571的上调表达与肝硬化肝组织中的表达调控趋势一致。在分离得到的原代人肝细胞中，miR-571在人肝细胞及肝星状细胞中可被促纤维化细胞因子转化生长因子β（transforming growth factor-β, TGF-β）诱导上调表达。与之相反，miR-652的血清水平异常与疾病分期无关，其反映了肝硬化患者循环单核细胞中该miRNA的一致性下调，而该下调可被细菌脂多糖（bacterial lipopolysaccharide, LPS）等促炎刺激所诱导。
研究结论：慢性肝病患者血清中miR-571与miR-652的水平异常，反映了它们在肝硬化发病机制相关的不同细胞亚群中，介导纤维化及炎症进程的潜在功能。