Molecular pathways leading to chronic graft dysfunction

描述(申请人提供)：肾移植肾功能丧失伴肾小管萎缩(TA)和间质纤维化(IF)，这是一组被称为慢性移植物肾病(CAN)的发现，导致大多数移植肾丢失，仍然是肾移植(KTX)的一个重大临床挑战。识别导致和触发移植物长期存活率的初始分子事件是最好的设计。我们的长期目标是确定不同和可识别的因素如何影响移植物中逐渐导致慢性同种异体移植物功能障碍的分子通路。具体的假设是，阐明基因表达谱与肾移植患者进展为CAN之间的相关性，将允许在非侵入性检测中识别和使用生物标记物进行早期诊断，并通过发现病因机制识别可能的治疗方案。我们的假说基于这样的观察：1)当移植物被确定为损伤时，其潜在的触发因素实际上可能是不可能破译的，以及2)许多参与慢性同种异体移植物损伤和纤维化形成的通路可能在损伤过程中非常早地被调节，当这些变化的下游影响仍然不是通过病理学明显的时候。因此，这些观察结果证明，通过微阵列技术进行早期移植物采样，以确定CAN疾病进展的早期分子标志物的作用是合理的。我们将通过针对以下特定目标的实验来验证我们的假设：1-阐明与同种异体肾移植慢性移植物功能障碍进展相关的基因，以开发有用的生物标志物来预测CAN并阐明CAN的病因机制。我们将前瞻性地研究植入前、再灌注后和KTX术后前9个月的移植物活检组织中的基因表达谱。2-TO表明，外周血单个核细胞(PBMC)或/和尿细胞中差异基因的表达(无创监测)与移植肾活检(有创监测)在进展为CAN过程中观察到的变化有关。我们将使用基因表达策略研究肾移植、尿样和PBMC中存在的差异，以确定新的非侵入性生物标记物。3-前瞻性地建立所选生物标志物在CAN早期诊断和预后中的临床应用价值。我们将在PBMC和尿样中使用实时RT-PCR，在一组独立的患者中使用有限的标记物来测试这些新的生物标记物的预测价值。我们将证明这组生物标志物可以预测导致CAN的早期变化，这在管理患者和设计更复杂的假设驱动的实验以直接测试CAN的可能因果机制时可能是有用的。公共卫生相关性：尽管在免疫抑制方面取得了进展，但慢性移植物肾病(CAN)是造成大部分移植肾丢失的原因，并且仍然是提高移植物长期存活率的主要临床挑战。CAN的病理生理学仍知之甚少，需要利用人类同种异体移植组织进行进一步的前瞻性研究。识别导致和触发移植物长期存活率的初始分子事件是最好的设计。

DESCRIPTION (provided by applicant): Loss of kidney graft function with tubular atrophy (TA) and interstitial fibrosis (IF), a set of findings termed chronic allograft nephropathy (CAN), causes most kidney allograft losses and remains a significant clinical challenge in kidney transplantation (KTx). Discerning the initial molecular events that predispose and trigger CAN represents the best design for improving long-term graft survival rates. Our long-term goal is to determine how the distinct and identifiable factors causing CAN affect the molecular pathways in the graft that progressively lead to chronic allograft dysfunction. The specific hypothesis is that the elucidation of correlations between gene expression profiles and progression to CAN in kidney transplant patients will allow the identification and use of biomarkers in non-invasive assays for early diagnosis and the recognition of possible therapeutic options through the discovery of causal mechanisms. We base the hypothesis on the observations that 1) underlying triggers for CAN may in fact be impossible to decipher, when the graft is sampled with established injury and, 2) many of the pathways involved in chronic allograft injury and fibrogenesis might be regulated very early in the course of the injury when the downstream effects of these alterations are still not evident by pathology. Therefore, these observations justify a role of early graft sampling by microarray technology to identify early molecular markers for CAN disease progression. We will test our hypothesis by carrying out experiments directed at the following specific aims: 1- To elucidate the genes associated with the progression to chronic graft dysfunction in kidney transplant allografts for both the development of useful biomarkers to predict CAN and for the elucidation of causal mechanisms of CAN. We will prospectively study gene expression profiling in graft biopsies at pre-implantation, post reperfusion and during the first 9 months post-KTx. 2-To demonstrates that differential gene expression in peripheral blood mononuclear cells (PBMC) or/and urine cells (non-invasive monitoring) are related to the changes observed in the renal allograft biopsies (invasive monitoring) during progression to CAN. We will study differences that exist in the kidney allograft, urine samples and in PBMC using gene expression strategies for identifying new non-invasive biomarkers. 3-To prospectively establish the clinical utility of using the selected biomarkers in the early diagnosis and prognosis of CAN. We will use real time-RT-PCR in PBMC and urine samples employing a limited panel of markers in an independent group of patients to test the predictive value of these new biomarkers. We will demonstrate that this panel of biomarkers can predict early changes leading to CAN, which can be useful in managing the patient and in designing more sophisticated hypothesis driven experiments to directly test possible causal mechanisms of CAN. PUBLIC HEALTH RELEVANCE: Despite of progresses in immunosuppression, chronic allograft nephropathy (CAN) causes most kidney allograft losses and remains the main clinical challenge for improving long-term graft survival rate. The pathophysiology of CAN remains poorly understood and requires further prospective study using human allograft tissue. Discerning the initial molecular events that predispose and trigger CAN represents the best design for improving long-term graft survival rates.