Role of innate immunity and injury in transplant-induced reactivation of MCMV

描述(由申请人提供)：在实体器官和骨髓移植的受者中，经常可以观察到潜伏的CMV重新激活，这是免疫受损宿主发病和死亡的重要原因。由于人巨细胞病毒的种属特异性，缺乏能够概括体内环境复杂性的合适模型，阻碍了对移植受者再激活因素的研究。因此，我们使用MCMV作为模型来研究潜伏期和再激活。鉴于我们之前专注于免疫活性小鼠模型，我们最近开发了一种新的感染病毒重新激活的移植模型，将潜伏感染小鼠的肾脏移植到缺乏功能B、T和NK细胞的免疫低下的NOD.Cg-PrkdcsordIL2rgtm1Wjl/Szj(NSG)受体。在这个模型中，再激活缓慢且零星地发生在2-6周内，并导致播散性感染，从移植的肾脏扩散到其他受者器官。该模型中的再激活动力学与接受标准免疫抑制方案治疗的移植受者中观察到的相似。因此，我们的新模型与巨细胞病毒病的临床设置高度相关，并使我们能够探索导致移植受者原发巨细胞病毒感染的新机制。我们推测，在这个模型中的重新激活是由于缺血/再灌注(I/R)损伤启动的病毒基因表达的激活，从而导致由天然免疫细胞介导的无菌炎症反应。I/R损伤导致损伤相关分子模式(DAMP)的形成，DAMP由先天免疫细胞上的模式识别受体识别，上调招募炎症细胞的趋化因子，通过释放活性氧和氮物种和蛋白水解酶导致进一步损害，以及激活信号通路的细胞因子激活控制MCMV即刻早期基因表达的转录因子。在缺乏适应性免疫反应的情况下，我们假设这会导致传染性病毒的重新激活。在这个应用中，我们建议在这个模型中表征损伤的标志物，并研究中性粒细胞和巨噬细胞在再激活过程中的需求。此外，我们还将研究活化蛋白C在阻断再激活方面的疗效。这种蛋白质目前正在临床上用于预防肾脏损伤。这些翻译研究可以为临床试验提供基础，以研究新的治疗方法，以防止免疫受损患者的CMV潜伏期再次激活。

DESCRIPTION (provided by applicant): Reactivation of latent CMV is frequently observed in recipients of solid organ and bone marrow transplants and is a significant cause of morbidity and mortality in immunocompromised hosts. Due to the species specificity of HCMV, investigation of the factors that induce reactivation in transplant recipients has been hampered by the lack of appropriate models that recapitulate the complexity of the in vivo environment. Therefore, we have used MCMV as a model to study latency and reactivation. Whereas we have previously focused on immunocompetent mouse models, we have more recently developed a new transplant model for reactivation of infectious virus, in which kidneys from latently infected mice are transplanted into immunocompromised NOD.Cg-PrkdcscidIL2rgtm1Wjl/Szj (NSG) recipients, which lack functional B, T, and NK cells. Reactivation in this model occurs slowly and sporadically over a period of 2-6 weeks, and results in a disseminated infection that spreads from the transplanted kidney to other recipient organs. The kinetics of reactivation in this model is similar to that observed in transplant recipients treated with standard immunosuppression protocols. Thus, our new model is highly relevant to the clinical setting of CMV disease and allows us to explore novel mechanisms responsible for primary CMV infection in transplant recipients. We hypothesize that reactivation in this model is due to activation of viral gene expression initiated by ischemia/reperfusion (I/R) injury, which leads to a sterile inflammatory response mediated by innate immune cells. I/R injury causes formation of damage associated molecular patterns (DAMPs), which are recognized by pattern recognition receptors on innate immune cells, up-regulation of chemokines that recruit inflammatory cells, which cause further damage through release of reactive oxygen and nitrogen species and proteolytic enzymes, and cytokines that activate signaling pathways leading to activation of transcription factors that control MCMV immediate early gene expression. In the absence of an adaptive immune response, we hypothesize that this leads to reactivation of infectious virus. In this application we propose to characterize markers of injury in this model and to investigate the requirement for neutrophils and macrophages in reactivation. In addition, we will investigate the therapeutic efficacy of activated protein C in blocking reactivation. This protein is currently in use clinically for prevention of kidney injury. These translational studies could provide the basis for clinical trials to investigate novel therapies to prevent reactivation of CMV from latency in immunocompromised patients.