Discovering tissue-specific biomarkers of radiation injury in SILAC-labeled mice

描述(申请人提供)：在全身辐射剂量为3-8Gy时，主要死因是造血综合征。其中许多死亡是可以通过对受害者进行快速分诊进行细胞因子治疗和积极的支持性护理来预防的。不幸的是，目前用于识别有造血综合征风险的患者的方法存在不准确、费用高、分析时间长和诊断延迟的问题。此外，这些方法都没有直接测量对骨髓的辐射损伤，也不表明存在残余的造血，而且在紧急情况下，大多数方法都不适合进行护理。因此，迫切需要一种现场可部署的诊断方法，以便在发生放射事故后用来确定哪些患者会患上可能致命的通常可治疗的造血综合征。我们建议建立一个在临床诊断中非常成功的范例，即损伤组织泄漏、脱落和/或分泌蛋白质。 进入血浆，在那里它们是有用的生物标记物，指示组织损伤的程度。先例包括心肌梗死中的肌钙蛋白、肝脏损伤中的转氨酶、肌肉损伤中的肌酸激酶以及胰腺突起中的脂肪酶。因此，我们假设，在辐射诱导的骨髓损伤之后，蛋白质从骨髓释放到血液中，在那里它们提供了有用的生物标记信号，预测了造血综合征的开始和严重程度。我们建议使用一种创新的方法来识别这些辐射诱导的骨髓损伤的血浆生物标记物，该方法结合了我们开发的靶向蛋白质组技术，并在生物标记物发现管道中进行了验证，与传统方法相比，这将使我们能够对非常大量(前所未有的)候选血浆生物标记物进行测试，从而显著增加我们的成功机会。目的1.利用SILAC标记的小鼠，鉴定辐射后骨髓中诱导的蛋白质，并随后检测数百个可能的组织损伤标志物，以确定照射后血浆中稳定升高的亚群。目的2：确定目标1中确定的候选骨髓损伤生物标记物的特征：a.在血浆中随时间、剂量范围和剂量率的稳定性；B.与临床终点的相关性(造血综合征的指标)；C.对造血系统的损害和辐射引起的损害的特异性；D.跨不同人群(儿童、老年人、性别、遗传易感性)的使用。目的3.确定在小鼠中发现的哪些骨髓损伤的辐射生物标记物在辐射暴露后在人类血液中升高，并开发一种护理点分析装置，这将形成后续人类临床验证试验的基础(超出本建议)。

DESCRIPTION (provided by applicant): At total body radiation exposures of 3-8 Gy, the predominant cause of death is the hematopoietic syndrome. Many of these deaths are preventable with rapid triage of victims for cytokine therapies and aggressive supportive care. Unfortunately current modalities for identifying patients at risk for the hematopoietic syndrome suffer from inaccuracy, high expense, long analysis times, and delayed diagnosis. Furthermore, none of these methods directly measures radiation damage to the bone marrow, nor do they indicate the existence of residual hematopoiesis, and most are not amenable to point-of-care in emergency conditions. Thus, there is a critical unmet need for a field-deployable diagnostic for use following a radiological incident to identify victims who will develop the potentially fatal ye often treatable hematopoietic syndrome. We propose to build upon a highly successful paradigm in clinical diagnostics, which is that injured tissues leak, shed, and/or secrete proteins into the plasma, where they are useful biomarkers indicating the extent of tissue injury. Precedents include the troponins in myocardial infarction, transaminases in liver injury, creatine kinase in muscle injury, and lipase in pancreatic processes. Accordingly, we hypothesize that following radiation-induced injury to the bone marrow, proteins are released from the marrow into the bloodstream, where they provide useful biomarker signals predictive of the onset and severity of the hematopoietic syndrome. We propose to identify these plasma biomarkers of radiation-induced marrow injury using an innovative approach incorporating targeted proteomic technologies that we have developed and validated in a biomarker discovery pipeline that will substantially increase our chances of success compared with traditional approaches by enabling the testing of a very large (unprecedented) number of plasma biomarker candidates. Aim 1. Using SILAC-labeled mice, identify proteins induced in the bone marrow in response to radiation, and subsequently test hundreds of these putative tissue injury markers to identify the subset that are stably elevated in the plasma post-exposure. Aim 2: Characterize candidate marrow injury biomarkers identified in Aim 1 with respect to their: a. stability in plasma over time, dose range, and dose rates b. correlation with clinical endpoints (indicators of hematopoietic syndrome) c. specificity for damage to the hematopoietic system and damage caused by radiation d. use across a heterogeneous population (pediatric, geriatric, gender, genetically susceptible) Aim 3. Determine which of the radiation biomarkers of marrow damage identified in the mouse are elevated in human blood following radiation exposure, and develop a point-of-care assay device that will form the basis of subsequent human clinical validation trials (beyond this proposal).