Department of Internal Medicine, Division of Nephrology and Transplantation, Erasmus MC, University Medical Center Rotterdam, Room Na-524, P.O. Box 2040, 3000 CA, Rotterdam, The Netherlands.
Rotterdam Transplant Group, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands.
Clin Epigenetics. 2021 Feb 11;13(1):32. doi: 10.1186/s13148-020-00969-4.
There is an unmet need for noninvasive markers specific for kidney transplant rejection. Such a marker may eventually overcome the need for a transplant biopsy. In this pilot study, the potential of circulating cell-free nucleosomes (CCFN) to serve as a biomarker for kidney transplant rejection was evaluated.
Forty de novo kidney transplant recipients were prospectively followed as part of a randomized, controlled clinical trial. Total CCFN (H3) and CCFN with the histone modifications H3K36me3 and H3 citrulline were measured in patients at four fixed time points: before transplantation and on days 3-6, 30 and 180 after kidney transplantation. In addition, serum collected at times of transplant rejection (n = 14) was analyzed. CCFN were measured with a Nu.Q™ Assay kit (VolitionRx), an ELISA-based assay using antibodies directed against nucleosomes.
For total CCFN (H3), H3K36me3, and H3 citrulline, the same pattern was seen over time: Concentrations were elevated shortly after transplantation (day 3-6) followed by a decline reaching baseline (pre-transplantation) values at days 30 and 180. At times of acute rejection, the median concentration of total CCFN (H3) was significantly higher compared to the stable situation (day 30): 4309 (3435-5285) versus 2885 (1668-3923) ng/mL, p < 0.05, respectively. Total CCFN (H3) had an acceptable ability to discriminate rejection from no rejection (AUC-ROC = 0.73) with a negative predictive value of 92.9%. For both histone modifications (H3K36me3 and H3 citrulline), there was no significant difference between episodes of acute rejection and the stable situation (day 30).
In this pilot study, total CCFN (H3) concentrations are increased at times of acute kidney transplant rejection. The high negative predictive value implies that whenever a patient experiences loss of renal transplant function and the total CCFN (H3) is not increased, causes other than acute rejection should be considered. Clinical implementation of total CCFN (H3) measurement may avoid unnecessary and potentially harmful kidney transplant biopsies.
目前需要一种针对肾移植排斥反应的非侵入性特异性标志物。这种标志物最终可能会取代移植活检。在这项初步研究中，评估了循环无细胞核小体（CCFN）作为肾移植排斥反应生物标志物的潜力。
40 名新诊断的肾移植受者作为一项随机对照临床试验的一部分进行前瞻性随访。在移植前以及移植后 3-6 天、30 天和 180 天四个固定时间点测量患者的总 CCFN（H3）和具有组蛋白修饰 H3K36me3 和 H3 瓜氨酸的 CCFN。此外，还分析了移植排斥时（n=14）采集的血清。使用 Nu.QTM 试剂盒（VolitionRx）测量 CCFN，该试剂盒是一种基于 ELISA 的检测试剂盒，使用针对核小体的抗体。
对于总 CCFN（H3）、H3K36me3 和 H3 瓜氨酸，随着时间的推移呈现出相同的模式：移植后不久浓度升高（第 3-6 天），然后下降，在第 30 天和 180 天达到基线（移植前）值。在急性排斥反应时，总 CCFN（H3）的中位数浓度明显高于稳定状态（第 30 天）：4309（3435-5285）与 2885（1668-3923）ng/mL，p<0.05。总 CCFN（H3）能够很好地区分排斥反应与无排斥反应（AUC-ROC=0.73），阴性预测值为 92.9%。对于两种组蛋白修饰（H3K36me3 和 H3 瓜氨酸），急性排斥反应与稳定状态（第 30 天）之间没有显著差异。
在这项初步研究中，急性肾移植排斥反应时总 CCFN（H3）浓度升高。高阴性预测值意味着，只要患者经历肾移植功能丧失，而总 CCFN（H3）没有增加，就应考虑其他原因而不是急性排斥反应。总 CCFN（H3）测量的临床应用可能会避免不必要的和潜在有害的肾移植活检。
