Alakulppi Noora, Seikku Paula, Jaatinen Taina, Holmberg Christer, Laine Jarmo
Research and Development, Finnish Red Cross Blood Service, Helsinki, Finland.
Transplantation. 2008 Nov 15;86(9):1222-8. doi: 10.1097/TP.0b013e3181883fb0.
Protocol biopsies are used to monitor allograft histology after transplantation. However, biopsy is an invasive procedure with potential complications, requires special facilities, and is unpractical for repeated monitoring of the graft. A noninvasive, robust, and rapid diagnostic method would be welcomed. Monitoring gene expression from blood samples could provide such a means.
Whole blood samples taken at the time of 3- or 6-month protocol biopsy in 31 pediatric renal transplant recipients, 13 of whom had biopsy-proven subclinical rejection (SCR), were studied. The samples were collected into tubes containing an RNA stabilization reagent enabling feasible collection during a normal ward schedule. In all patients, the gene expression of candidate genes CD154 and inducible T-cell co-stimulator (ICOS) was measured. A low-density array containing 90 immunologic-related genes were measured with real-time quantitative PCR (RT-QPCR) in 10 patients. In addition, a whole genome microarray analysis was performed in eight patients.
Neither CD154 nor ICOS gene expression was diagnostic for SCR (median expression level 1.25 vs. 1.16 and 1.95 vs. 1.61 for CD154 and ICOS, respectively). In addition, expression levels of none of the genes on the low-density array were associated with SCR. Finally, in the microarray analysis none of the found differences between SCR and normal patients' gene expression could be validated with RT-QPCR in 17 genes.
In our relatively small series no robust whole blood gene expression biomarker for SCR was found. Further studies are needed to determine whether small changes in expression may provide a supporting diagnostic method.
移植后采用方案活检来监测同种异体移植物的组织学情况。然而，活检是一种侵入性操作，存在潜在并发症，需要特殊设备，且对移植物进行重复监测并不实用。一种非侵入性、可靠且快速的诊断方法将会受到欢迎。监测血样中的基因表达可能提供这样一种手段。
对31名小儿肾移植受者在3个月或6个月方案活检时采集的全血样本进行研究，其中13人经活检证实有亚临床排斥反应（SCR）。样本收集到含有RNA稳定试剂的试管中，以便能在正常病房流程中可行地进行采集。对所有患者测量候选基因CD154和诱导性T细胞共刺激分子（ICOS）的基因表达。用实时定量PCR（RT-QPCR）对10名患者测量了包含90个免疫相关基因的低密度阵列。此外，对8名患者进行了全基因组微阵列分析。
CD154和ICOS基因表达均不能诊断SCR（CD154和ICOS的中位表达水平分别为1.25对1.16以及1.95对1.61）。此外，低密度阵列上的基因表达水平均与SCR无关。最后，在微阵列分析中，SCR与正常患者基因表达之间发现的差异在17个基因中均无法通过RT-QPCR得到验证。
在我们这个相对较小的队列中，未发现用于诊断SCR的可靠全血基因表达生物标志物。需要进一步研究以确定表达的微小变化是否可能提供一种辅助诊断方法。
