Co-expression Analysis Reveals Dysregulated miRNAs and miRNA-mRNA Interactions in the Development of Contrast-induced Acute Kidney Injury [miRNA]

Purpose: The pathogenesis of contrast-induced acute kidney injury (CI-AKI) has not yet been clearly understood. miRNAs are important mediators which normally work by post-transcriptional degradation of target mRNAs. Emerging evidence indicated a number of differentially expressed miRNAs in CI-AKI following intravenous contrast medium injection. However, there exist differences in the pathological mechanisms and incidences of CI-AKI between intravenous and intra-arterial contrast administration. We aimed to investigate the critical roles of dysregulated miRNAs and the correlated mRNAs in the kidney injury following intra-arterial contrast exposure. Methods: Based on a reliable CI-AKI rat model, we sought to investigate the roles of miRNA-mRNA interactions in the kidney injury following intra-arterial contrast exposure using the Illumina Genome Analyzer IIx. Results: In the study, 36 differentially expressed mature miRNAs were identified ( fold change > 1.5 and p value < 0.05) in the kidney of CI-AKI rats (n = 3) compared with controls (n = 3), consisting of 23 up-regulated and 13 down-regulated ones. Bioinformatics analysis revealed that Wnt, TGF-β, and AMPK signaling pathways were most likely to be modulated by these dysregulated miRNAs. Around 453 dysregulated genes ( fold change > 2.0 and p value < 0.05) were identified. Integrated analysis revealed 2037 putative miRNA-mRNA pairs with negative correlations. Of which, 6 differential miRNAs and 13 genes were selected for further quantitative real-time polymerase chain reaction validation (n = 6 for each group), and a well correspondence between the 2 techniques was observed. Conclusions: In conclusion, our present study contributes to the first evidence of miRNA-mRNA regulations in the development of kidney injury following an intra-arterial contrast injection route. These novel findings provide insights into the underlying mechanisms of CI-AKI. Three-month-old male Sprague-Dawley rats were used in this study. Kidney mRNA and miRNA profiles of CI-AKI rats and controls were generated by deep sequencing, in triplicate, using Illumina Illumina Genome Analyzer IIx.

研究背景与目的：对比剂诱导急性肾损伤（contrast-induced acute kidney injury, CI-AKI）的发病机制尚未完全阐明。微小RNA（microRNAs, miRNAs）是重要的调控介质，通常通过对靶mRNA进行转录后降解发挥生理功能。现有研究表明，静脉注射造影剂后诱发的CI-AKI样本中存在大量差异表达的miRNAs。然而，静脉与动脉内造影剂给药方式在CI-AKI的病理机制与发病率上存在显著差异。本研究旨在探讨动脉内造影剂暴露后肾损伤中异常表达的miRNAs及其关联mRNA的关键调控作用。

研究方法：基于稳定构建的CI-AKI大鼠模型，本研究采用Illumina Genome Analyzer IIx测序平台，探究动脉内造影剂暴露后肾损伤中的miRNA-mRNA互作调控机制。

研究结果：本研究在CI-AKI模型大鼠（n=3）与对照大鼠（n=3）的肾脏组织中，共筛选得到36个差异表达的成熟miRNAs（倍数变化>1.5且P值<0.05），其中23个表达上调，13个表达下调。生物信息学分析显示，Wnt、转化生长因子-β（transforming growth factor-β, TGF-β）以及AMPK信号通路最有可能受到这些失调miRNAs的调控。同时共鉴定得到453个差异表达基因（倍数变化>2.0且P值<0.05）。整合分析后共得到2037个呈负相关的潜在miRNA-mRNA调控对。随后选取其中6个差异miRNAs与13个基因进行定量实时聚合酶链式反应（quantitative real-time polymerase chain reaction, qRT-PCR）验证（每组n=6），两种检测技术的结果具有良好的一致性。

研究结论：本研究首次为动脉内造影剂注射诱发肾损伤过程中的miRNA-mRNA调控机制提供了实验证据。上述全新发现为阐明CI-AKI的潜在发病机制提供了新的视角。本研究选用3月龄雄性Sprague-Dawley大鼠作为实验动物。通过Illumina Genome Analyzer IIx测序平台对CI-AKI模型大鼠与对照大鼠的肾脏组织进行三次重复深度测序，获取其mRNA与miRNA表达谱。