Supplementary Material for: Tissue miRNA profile is associated with acute tubular necrosis, rejection phenotypes and BK polyomavirus-associated nephropathy in human kidney allografts

Introduction. MicroRNAs, short noncoding RNAs, are involved in the modulation of gene expression, mainly by inhibiting the translation of mRNAs. Under physiological conditions, miRNAs are involved in viral infections and immune responses, among others; aberrant miRNA expression has been associated with kidney transplant pathologies, but a comprehensive comparison of later, particularly in tissue sections, is still pending.
Methods. We used the genome-wide screening of miRNAs to identify those potentially involved in the disease processes after kidney transplantation. RNA was isolated from formalin-fixed paraffin- embedded kidney biopsy samples. Study included 8 patients with acute tubular necrosis (ATN), 8 patients with antibody-mediated rejection (ABMR), 10 patients with T-cell-mediated rejection (TCMR), 10 patients with BK polyomavirus-associated nephropathy (BKPyVAN) and 12 surveillance biopsies from patients with stable allograft function and no major abnormalities (normal allografts, CTRL).
Results. We found 136 miRNAs differentially expressed in diseased kidney transplant tissue compared with normal allografts; of these, 74 miRNAs were differentially expressed in ABMR, 65 in ATN, 62 in BKPyVAN, 69 in TCMR, and 16 miRNAs were not associated with a specific disease phenotype. In addition, 29 miRNAs were differently expressed between ABMR and ATN, 39 between BKPyVAN and TCMR, and 20 between BKPyVAN and ABMR, and 38 between ABMR and TCMR.
Conclusion. Our findings show that miRNA derived from kidney allograft biopsy samples represent an additional diagnostic tool to distinguish different disease phenotypes. This finding has the potential to assist clinicians in therapeutic decision making and to translate to non-invasive monitoring of patients, e.g. blood samples.

引言：微小核糖核酸（MicroRNAs，miRNAs）是一类短链非编码RNA，主要通过抑制信使核糖核酸（mRNA）的翻译过程参与基因表达调控。在生理状态下，miRNAs参与病毒感染、免疫应答等多种生命过程；异常表达的miRNAs与肾移植相关病理改变密切相关，但后续针对此类病变的全面比较分析，尤其是在组织切片层面的研究仍有待开展。
方法：本研究采用全基因组水平的miRNAs筛选策略，以鉴定肾移植术后疾病进程中潜在发挥作用的miRNAs。从福尔马林固定石蜡包埋的肾活检组织样本中提取核糖核酸（RNA）。研究共纳入8例急性肾小管坏死（acute tubular necrosis, ATN）患者、8例抗体介导排斥反应（antibody-mediated rejection, ABMR）患者、10例T细胞介导排斥反应（T-cell-mediated rejection, TCMR）患者、10例BK多瘤病毒相关性肾病（BK polyomavirus-associated nephropathy, BKPyVAN）患者，以及12例移植肾功能稳定且无显著异常的患者的监测活检样本（正常移植肾对照组，CTRL）。
结果：相较于正常移植肾组织，本研究在病变肾移植组织中鉴定出136个差异表达的miRNAs；其中74个miRNAs在ABMR组中呈现差异表达，65个在ATN组中差异表达，62个在BKPyVAN组中差异表达，69个在TCMR组中差异表达，另有16个miRNAs未与特定疾病表型相关联。此外，ABMR与ATN组间存在29个差异表达miRNAs，BKPyVAN与TCMR组间为39个，BKPyVAN与ABMR组间为20个，ABMR与TCMR组间为38个。
结论：本研究结果表明，源自肾移植活检样本的miRNAs可作为区分不同疾病表型的辅助诊断工具。该发现有望协助临床医生制定治疗决策，并可转化为患者的无创监测手段，例如通过血液样本开展相关检测。