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）的翻译参与基因表达调控。生理状态下，miRNAs参与病毒感染、免疫应答等多种生理过程；而miRNA表达异常已被证实与肾移植病理损伤相关，但目前针对术后不同病理状态的全面比较研究，尤其是基于组织切片的系统分析，仍有待开展。

## 方法
我们通过全基因组miRNA筛选，鉴定肾移植术后疾病进程中潜在的相关miRNA。实验材料取自福尔马林固定石蜡包埋的肾活检组织样本。本研究共纳入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、无显著异常的监测活检样本（正常移植肾对照组，CTRL）。

## 结果
相较于正常移植肾对照组，我们在患病肾移植组织中检出136个差异表达miRNA；其中74个在ABMR组中呈现差异表达，65个在ATN组，62个在BKPyVAN组，69个在TCMR组，另有16个miRNA未与特定疾病表型相关联。此外，ABMR组与ATN组间存在29个差异表达miRNA，BKPyVAN组与TCMR组间39个，BKPyVAN组与ABMR组间20个，ABMR组与TCMR组间38个。

## 结论
本研究结果表明，源自肾移植活检样本的miRNA可作为区分不同肾移植术后疾病表型的辅助诊断工具。这一发现有望辅助临床医师制定个体化治疗决策，并可拓展应用于患者的无创监测（例如血液样本检测）。