Predictors for drug selection and minimization in pediatric liver transplantation

该项目的长期目标是将器官排斥反应和免疫抑制毒性分别降至最低 儿童肝移植(LTX)。LTX前淋巴细胞耗尽使类固醇得以避免并降低 需要他克莫司免疫抑制。如果更好地了解潜在的机制，它们可能会 用于进一步减少首次排斥反应(50%)和药物最小化期间的复发排斥反应(30%) 这个协议。初步工作让我们假设，捐赠者特定的低反应性和调节- 儿童LTX术后早期排斥反应以高度可变的时间间隔达到抑制效果 不含类固醇的淋巴细胞耗尽免疫抑制。我们进一步假设，这种变异性在 免疫调节与扩展的MHC中的单核苷酸多态(SNP)模式相关 区域基因从属于增殖、凋亡、记忆和B细胞依赖的功能。一项临床试验 我们中心将在耗尽5 mg/kg兔抗人胸腺细胞后给予他克莫司治疗 80例淋巴结炎患儿血清球蛋白(RATG)测定。拟议的机械增编研究将需要一系列 所有儿童在LTX治疗前、治疗后1个月、3个月和12个月的外周血样。具体目标是1. 供体特异性同种异体反应性，T-reg/抑制细胞(CD4+CD25+，CD8+28-)的纵向特征， 和抗-HLAALTO抗体，2.LTX前的29个SNPs分布在14个 MHC基因，其初步分布模式在排斥者之间显著不同(活组织检查证实 LTX后60天的排斥反应)和非排斥反应者。这项研究将在80名儿童及其亲生父母身上进行。 显示&>或&lt；50%预期从父母传播给拒绝者且传播不同的SNPs 在拒绝者和非拒绝者之间的显著差异，将被用于识别与传递有关的候选基因座 不平衡检验，以及3.验证结果组内的潜在候选基因/基因座，通过a)测量 CFSE-MLR检测供者特异性T和B细胞亚群的增殖/凋亡/记忆反应 基因组mRNA表达，以补充SNP关联，并将假阳性降至最低，以及c)基因座- 候选基因座c的特异性基因表达(M RNA)。如果成功，未来研究结果的应用可能会 改善LTX前药物选择，例如，如果SNP模式预测排斥反应，则分配类固醇。此外，LTX后的药物 例如，当T-reg/T-sup出现时，可以使最小化更安全。

The long term goal of this project is to minimize organ rejection and immunosuppressant toxicity, in each child with liver transplantation (LTx). Pre-LTx lymphocyte depletion permits steroid avoidance and lowers need for Tacrolimus immunosuppression. If underlying mechanisms were better understood, they could be used to reduce further, primary rejection (50%) and recurrent rejection during drug minimization (30%) on this protocol. Preliminary work leads us to hypothesize that donor-specific hyporeactivity and regulatory- suppressive effect are achieved at highly variable intervals among pediatric LTx with early rejection after steroid-free lymphocyte-depleting immunosuppression. We further hypothesize that this variability in immune-modulation is associated with patterns of single nucleotide polymorphisms (SNP) in extended MHC- region genes subserving proliferation, apoptosis, memory and B-cell-dependent functions. A clinical trial at our center will administer steroid-free Tacrolimus after depletion with 5 mg/kg rabbit anti-human-thymocyte globulin (rATG) to 80 children with LTx. The proposed mechanistic addendum study will entail serial peripheral blood samples from all children before and at 1, 3, and 12 months post-LTx. Specific aims are 1. Longitudinal characterization of donor-specific alloreactivity, T-reg/suppressor cells (CD4+CD25+, CD8+28-), and anti-HLA alto-antibodies in each child, 2. Pre-LTx characterization of 29 SNPs distributed among 14 MHC genes, whose preliminary distribution patterns differ significantly between rejectors (biopsy-proven rejection at 60 days post-LTx), and non-rejectors. This will be done in 80 children and their biologic parents. SNPs showing > or < 50% expected transmission from parents to rejectors and whose transmission differs significantly between rejectors and non-rejectors, will be used to identify candidate loci with the transmission disequilibrium test, and 3. Validate potential candidate genes/loci within outcome groups, by a) measuring donor-specific proliferative/apoptotic/memory responses in T- and B-cell subsets by CFSE-MLR, b) whole genome mRNA expression to complement SNP associations, and minimize false-positives, and c) locus- specific gene expression (mRNA) for candidate loci c). If successful, future application of study results could improve pre-LTx drug selection, e.g.,allocating steroids if SNP patterns predict rejection. Also, post-LTx drug minimization could be made safer, e.g., when T-reg/T-sup appear.