Circulating Liver-Specific miR-122 as a Novel Potential Biomarker for Diagnosis of Cholestatic Liver Injury

BackgroundCirculating microRNA-122 (miR-122) has been increasingly reported to be a potential biomarker for drug-, viral-, alcohol- and chemical-induced liver injury. The present study was initiated to determine the potential of circulating miR-122 as a biomarker for cholestatic liver injury.MethodsBoth bile-duct ligation (BDL) mice and patients with biliary calculi were employed as cholestatic liver injury models, and serum miR-122 level was determined by stem-loop real-time reverse-transcription PCR (SLqRT-PCR). All quantitative PCR values were normalized to those for U6 RNA and calculated with the 2−△Ct method.ResultsSerum miR-122 increased significantly after BDL-induced cholestatic injury and showed a similar time course to ALT concentrations. Compared with the sham controls, BDL mice had increased serum levels of miR-122 by 24.36±12.86, 423.63±322.89, 4.43±2.02 and 12.23±8.92 folds after 1, 3, 7 and 14 days, respectively. Moreover, serum miR-122 level was substantially higher in patients with biliary calculi than that in the healthy control group. In addition, patients with severe liver injury showed significantly higher levels of serum miR-122 when compared with healthy controls or patients with mild or moderate liver injury. Furthermore, serum miR-122 was found to show significant diagnostic value for biliary calculi by yielding an AUC (the areas under the receiver operating characteristic curve) of 0.931 with 77.4% sensitivity and 96.4% specificity in discriminating biliary calculi from healthy controls.ConclusionCollectively, these data suggest that serum miR-122 has strong potential as a novel, specific and noninvasive biomarker for diagnosis of cholestasis-induced liver injury.背景：越来越多的研究报道，循环微小RNA-122（miR-122）可作为药物、病毒、酒精及化学物质诱导性肝损伤的潜在生物标志物。本研究旨在探讨循环miR-122作为胆汁淤积性肝损伤生物标志物的潜力。 方法：本研究采用胆管结扎（bile-duct ligation，BDL）小鼠及胆道结石患者作为胆汁淤积性肝损伤模型，通过茎环实时逆转录聚合酶链式反应（stem-loop real-time reverse-transcription PCR，SLqRT-PCR）检测血清miR-122水平。所有定量PCR数据均以U6 RNA为内参进行标准化，并采用2^−ΔCt法进行计算。 结果：BDL诱导的胆汁淤积性损伤后，血清miR-122水平显著升高，且其时间变化趋势与丙氨酸氨基转移酶（ALT）浓度一致。与假手术对照组相比，BDL小鼠在造模后1、3、7、14天的血清miR-122水平分别升高了24.36±12.86、423.63±322.89、4.43±2.02及12.23±8.92倍。此外，胆道结石患者的血清miR-122水平显著高于健康对照组。进一步分析显示，重度肝损伤患者的血清miR-122水平显著高于健康对照组及轻、中度肝损伤患者。此外，血清miR-122对胆道结石具有良好的诊断价值：在区分胆道结石与健康对照的研究中，其受试者工作特征曲线下面积（Area Under the Receiver Operating Characteristic Curve，AUC）为0.931，灵敏度为77.4%，特异度为96.4%。 结论：综上，本研究数据表明，血清miR-122具备成为新型、特异性且无创的胆汁淤积性肝损伤诊断生物标志物的巨大潜力。