Integrating Mechanistic Insights from Diverse Models to Prevent CMV Reactivation following Transplantation

描述(由申请人提供)：尽管预防性使用了有效的抗病毒药物，但移植后潜伏的巨细胞病毒(CMV)的全面重新激活仍然是一个重要的临床问题。因为它们针对的是病毒DNA聚合酶，所以只有在病毒从潜伏期重新激活后，它们才会激活。它们的有效性也受到毒性和 通过耐药菌株的出现。供者特异性同种异体免疫耐受，即移植受者对供体抗原无反应，但对其他外来抗原仍保持完整的免疫应答，自20世纪50年代初以来一直是移植的“圣杯”。最近，几个实验方案已经实现了这一目标，“耐受时代”似乎即将到来。先前的研究表明，小鼠巨细胞病毒(MCMV)的重新激活需要异体炎症反应和免疫抑制药物(ISD)的结合，而供体特异性耐受模型将消除炎症反应，避免ISD的需要。另外，最近，通过对MCMV重新激活的动物模型和体外/体外HCMV重新激活模型的研究，出现了两个中心主题：参与裂解复制的病毒基因的表达受到诱导病毒基因组异染色质的表观遗传因子的抑制；由炎性免疫反应激活的信号通路通过病毒DNA的表观遗传重编程诱导病毒重新激活，从而使直接早期的基因从转录抑制中释放，导致裂解复制。这些主题构成了三个独立但相互关联的项目中提出的研究的基础：1)临床相关模型中肾移植后潜伏的MCMV重新激活的机制；2)髓系细胞中HCMV潜伏和重新激活的机制；以及3)移植耐受中MCMV感染、潜伏和重新激活的机制。三个核心将支持成功完成这些项目中的研究所需的服务：A)微血管外科和组织病理学；B)精密细胞分离和分析；以及C)行政服务。该计划的统一和中心假设是，潜伏的CMV的重新激活是由炎症介质诱导的，炎症介质激活信号通路，导致病毒基因组的表观遗传重新编程，导致即时早期(IE)基因表达，最终导致感染性病毒的重新激活。我们认为，阻断这些信号通路，无论是通过干扰特定的信号通路，阻断表观遗传修饰，还是通过供体特异性耐受，都可以阻止CMV的重新激活。我们预计，在这一高度协作的基金会中整合来自三个项目的机械性见解将在推动该领域向前发展以及促进预防而不是治疗CMV重新激活的新战略的发展方面起决定性作用。

DESCRIPTION (provided by applicant): Overall Reactivation of latent Cytomegalovirus (CMV) remains an important clinical problem following transplantation, despite the prophylactic use of efficacious antiviral agents. Because these target the viral DNA polymerase, they are only active after the virus has reactivated from latency. Their effectiveness is also limited by toxicities and by the emergence of resistant strains. Donor- specific allo-immune tolerance, whereby a transplant recipient is hypo-responsive to donor antigens but continues to have intact immune-responsiveness to other foreign antigens has been the `Holy Grail' of transplantation since the early 1950's. Recently, several experimental protocols have achieved this goal, and the `era of tolerance' seems near. Prior studies have demonstrated that murine CMV (MCMV) reactivation requires the combination of an allo-inflammatory response and immunosuppressive drugs (ISD), while a donor-specific tolerant model would abrogate the inflammatory response, and avoid the need for ISD. Also recently, two central themes have emerged from a combination of studies of animal models of MCMV reactivation and ex vivo/in vitro models of HCMV reactivation: expression of viral genes involved in lytic replication is repressed by epigenetic factors that induce heterochromatinization of viral genomes; and signaling pathways activated by an inflammatory immune response induce reactivation of the virus through epigenetic reprogramming of viral DNA, such that the immediate early genes are released from transcriptional repression, leading to lytic replication. These themes form the basis for studies proposed in 3 separate but inter-related projects studying: 1) Mechanisms of reactivation of latent MCMV following kidney transplantation in a clinically relevant model; 2) Mechanisms of latency and reactivation of HCMV in myeloid lineage cells; and 3) MCMV infection, latency and reactivation in transplantation tolerance. Three Cores will support services needed for the successful completion of studies within these Projects: A) Microvascular surgery and histopathology; B) Precision cell isolation and analysis; and C) Administrative services. The unifying and central hypothesis of the Program Project is that reactivation of latent CMV is induced by inflammatory mediators, which activate signaling pathways, leading to epigenetic reprogramming of viral genomes, resulting in induction of immediate early (IE) gene expression, and ultimately, to reactivation of infectious virus. We believe that blockade of these signaling pathways, either by interfering with specific signaling pathways, blocking epigenetic modifications, or by donor- specific tolerance, prevent reactivation of CMV. We anticipate that integrating mechanistic insights derived from the three projects in this highly collaborative effor will be decisive in moving the field forward and in fostering the development of novel strategies to prevent, rather than treat CMV reactivation.