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

描述（由申请人提供）：潜伏巨细胞病毒的再激活在实体器官和骨髓移植受体中经常观察到，是免疫功能低下宿主发病和死亡的重要原因。由于HCMV的物种特异性，由于缺乏适当的模型来概括体内环境的复杂性，对移植受者诱导再激活的因素的研究一直受到阻碍。因此，我们使用MCMV作为模型来研究潜伏期和再激活。鉴于我们之前关注的是免疫功能正常的小鼠模型，我们最近开发了一种新的移植模型，用于感染病毒的再激活，其中将潜伏感染小鼠的肾脏移植到免疫功能低下的NOD中。Cg-PrkdcscidIL2rgtm1Wjl/Szj （NSG）受体，缺乏功能性B、T和NK细胞。该模型中的再激活在2-6周的时间内缓慢而零星地发生，并导致从移植肾扩散到其他受体器官的弥散性感染。该模型中的再激活动力学与在标准免疫抑制方案中观察到的移植受者相似。因此，我们的新模型与CMV疾病的临床环境高度相关，并使我们能够探索移植受者原发性CMV感染的新机制。我们假设该模型中的再激活是由于缺血/再灌注（I/R）损伤引发的病毒基因表达激活，从而导致先天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（DAMPs）的形成，这些损伤相关分子模式被先天免疫细胞上的模式识别受体识别，募集炎症细胞的趋化因子上调，炎症细胞通过释放活性氧、活性氮和蛋白水解酶导致进一步的损伤，以及激活信号通路的细胞因子，从而激活控制MCMV即时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，我们建议表征该模型中的损伤标志物，并研究中性粒细胞和巨噬细胞在再激活中的需求。此外，我们将研究活化蛋白C阻断再激活的治疗效果。这种蛋白目前在临床上用于预防肾损伤。这些转化研究可以为临床试验提供基础，以研究新的治疗方法，以防止免疫功能低下患者的潜伏性巨细胞病毒再激活。

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.