Modeling concurrent cytomegalovirus infection and transplantation tolerance

 描述(申请人提供)：巨细胞病毒(CMV)血清阳性在器官捐赠者和接受者中都很普遍。在终生免疫抑制下，移植后巨细胞病毒病是移植物和受者预后不良的重要因素。移植耐受可以完全避免免疫抑制，现在临床上是可以实现的。在这样的耐受性宿主中，CMV感染的过程可能如何被改变还没有被表征。相反，CMV并发感染如何改变耐受性也在很大程度上是未知的。在这个应用中，我们建议使用一个具有高度临床相关性的移植耐受小鼠模型来研究CMV感染和移植耐受之间的相互作用。在该模型中，供体特异性耐受是通过移植前给予供体“阴性免疫”来实现的，供体细胞用交联剂1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide(ECDI)处理。我们的小鼠研究已经在非人类灵长类动物上进行了正在进行的实验，证明了这种策略在诱导同种和异种耐受方面都有很好的效果。更重要的是，我们的同事最近发表了一项使用ECDI固定的多肽偶联自体细胞治疗多发性硬化症的首例临床试验，确立了这种新的耐受策略的可行性、安全性和有效性。在这个模型中，我们使用小鼠巨细胞病毒，我们证明了急性和潜伏的巨细胞病毒感染都削弱了耐受性的诱导和破坏了已建立的耐受性，可能是通过干扰受体酪氨酸激酶(RTK)介导的胞吐作用和直接或间接干扰宿主髓系来源的抑制细胞(MDSCs)的扩张。相反，宿主中供体特异性耐受的存在抑制了潜伏的CMV重新激活所必需的即刻早期(IE)基因转录。基于这些发现，我们假设CMV感染通过破坏RTK介导的宿主细胞和ECDI固定的供体细胞之间的耐受性相互作用来损害耐受性，反过来，耐受性通过抑制移植诱导的炎症来抑制CMV的重新激活，这是CMV基因组表观遗传重新编程的必备早期触发因素。在这一应用中，我们建议研究：(1)CMV诱导的耐受损伤的效果和机制；(2)耐受诱导的抑制CMV重新激活的效果和机制。我们的长期目标是确定有针对性的治疗方法，以建立和维持CMV感染宿主的稳定耐受。

 DESCRIPTION (provided by applicant): Cytomegalovirus (CMV) seropositivity is highly prevalent among both organ donors and recipients. Under life-long immunosuppression, post-transplant CMV disease is a significant contributor to poor graft and recipient outcome. Transplant tolerance allows complete avoidance of immunosuppression and is now clinically achievable. In such tolerant hosts, how the course of CMV infection may be modified has not been characterized. Conversely, how concurrent CMV infection may alter the outcome of tolerance is also largely unknown. In this application, we propose to examine the reciprocal interaction between CMV infection and transplant tolerance, using a highly clinically relevant murine model of transplant tolerance. In this model, donor-specific tolerance is achieved by pre-transplant delivery of donor "negative vaccination" consisting of donor cells treated with a crosslinker 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (ECDI). Our murine studies have already led to ongoing experiments in non-human primates, demonstrating promising efficacy of this strategy for both allogeneic and xenogeneic tolerance induction. More importantly, our colleagues recently published a first-in-man clinical trial using ECDI-fixed peptide-coupled autologous cells for multiple sclerosis, establishing the feasibility, safety and efficacy of this novel tolerance strategy. Using murine CMV in this model, we demonstrate that both acute and latent CMV infection impair tolerance induction and destabilize established tolerance, likely via interfering with Receptor Tyrosine Kinase (RTK)-mediated efferocytosis and directly or indirectly interfering with expansion of host myeloid derived suppressor cells (MDSCs). Conversely, presence of donor-specific tolerance in the host suppresses immediate early (IE) gene transcription necessary for latent CMV reactivation. Based on these findings, we hypothesize that CMV infection impairs tolerance via disrupting RTK-mediated tolerogenic interaction between host cells and ECDI-fixed donor cells, and conversely tolerance inhibits CMV reactivation via inhibiting transplant-induced inflammation, an obligatory early triggers for CMV genome epigenetic reprogramming. In this application, we propose to examine: (1) the effects and mechanisms of CMV-induced tolerance impairment; (2) the effects and mechanisms of tolerance-induced inhibition of CMV reactivation. Our long-term goal is to define targeted therapies for establishing and maintaining stable tolerance in hosts with CMV infection.