CMV-Induced Embryonic Cochlear Pathogenesis

描述（由申请人提供）：先天性巨细胞病毒（CMV）感染是儿童感音神经性听力损失（SNHL）最常见的非遗传原因，占所有SNHL的20%至60%。据估计，美国每年至少有8000名新生儿患有先天性巨细胞病毒诱导的SNHL，其中很大一部分儿童在新生儿期后表现为延迟发病和进行性听力恶化。目前，对cmv诱导出生缺陷的机制知之甚少。由于子宫内巨细胞病毒感染导致SNHL，而出生后感染则不会，因此我们假设巨细胞病毒诱导的耳蜗畸形是由病毒诱导的多种宿主（胚胎）细胞信号通路的失调引起的，而这些通路是正常耳蜗形态发生所必需的，并且畸形发生的严重程度是时间依赖性的。我们最近建立了一种新的CMV诱导耳蜗畸形的小鼠胚胎器官培养模型，并证明了体外CMV感染小鼠胚胎耳蜗可引起严重的耳蜗表型异常和迷路炎。我们的初步结果表明，这种新的胚胎小鼠耳蜗培养模型模拟了先天性巨细胞病毒感染儿童的病理。我们的目的是利用我们的新型体外胚胎小鼠器官培养模型cmv诱导的耳蜗畸形，开始描述cmv诱导的耳蜗异常的分子病理学。从长远来看，我们的目标是确定cmv诱导的耳蜗畸形发生的分子机制，并确定新的耳蜗特异性产后治疗的关键细胞靶点。我们设计了一系列相互关联的实验来实现三个具体目标。目的1：表征mcmv诱导的胚胎耳蜗形态、组织分化和细胞增殖的变化。目的2：确定mcmv诱导的一组“耳蜗相关”信号分子的基因表达差异。目的3：确定mcmv诱导的耳蜗异常分子病理学的时间依赖性差异。我们的初步研究结果将提供cmv诱导耳蜗病理的详细分子表型。一个知情和合理的框架将会出现，在这个框架内，未来的机制研究可能会计划和提出，以确定哪些细胞信号通路在cmv诱导的耳蜗发病机制中是功能必需的，以及可能针对新疗法的假定靶点将会出现。我们的体外模型还具有附加的翻译价值，为所有类别的新候选，耳蜗靶向，产后抗巨细胞病毒药物（包括抗病毒药物）的初始筛选提供了系统。这条研究路线在临床上至关重要，因为巨细胞病毒诱导的SNHL的患病率相当高，目前的抗病毒治疗本身具有致畸性，并且感染儿童长期使用目前的抗病毒药物存在严重的安全问题。

DESCRIPTION (provided by applicant): Congenital cytomegalovirus (CMV) infection is the most common non-genetic cause of sensorineural hearing loss (SNHL) in children, accounting for between 20 and 60% of all SNHL. It is estimated that at least 8000 infants born annually in the US will have congenital CMV-induced SNHL, with a significant proportion of these children exhibiting delayed onset and progressive deterioration of hearing after the newborn period. Currently, little is known about the mechanism underlying CMV-induced birth defects. Since in utero CMV infection causes SNHL whereas postnatal infection does not, we postulate that CMV-induced cochlear malformations are caused by viral-induced dysregulation of multiple host (embryonic) cell signaling pathways essential for normal cochlear morphogenesis and that the severity of dysmorphogenesis is time-dependent. We have recently developed a novel mouse embryonic organ culture model of CMV-induced cochlear malformations and demonstrate that active CMV infection of embryonic mouse cochlears in vitro induces severely abnormal cochlear phenotypes and labyrinthitis. Our preliminary results indicate that this novel embryonic mouse cochlear culture model mimics the pathology seen in children with congenital CMV infection. Our objective is to initiate delineation of the molecular pathology of the CMV-induced cochlear abnormalities using our novel in vitro embryonic mouse organ culture model of CMV-induced cochlear malformation. Long-term, our goal is to identify the molecular mechanisms underlying CMV-induced cochlear dysmorphogenesis and identify key cellular targets against which new cochlear- specific, postnatal therapies can be directed. We have designed a series of interrelated experiments to address three Specific Aims. Aim 1: Characterize mCMV-induced changes in embryonic cochlear morphology, histodifferentiation and cell proliferation in vitro. Aim 2: Determine mCMV-induced differences in the gene expression of a focused set of "cochlea-related" signaling molecules. Aim 3: Determine time-dependent differences in the molecular pathology of mCMV-induced cochlear abnormalities. The results of our initial studies will provide a detailed molecular phenotype of CMV-induced cochlear pathology. An informed and rational framework will emerge within which future mechanistic studies may be planned and proposed to identify which cellular signaling pathways are functionally essential for CMV-induced cochlear pathogenesis, and likely putative targets against which new therapies can be directed will emerge. Our in vitro model also has the added translational value of providing a system for initial screening of all classes of new candidate, cochlear-targeted, postnatal anti-CMV drugs, including antivirals. This line of investigation is clinically critical because the prevalence of CMV-induced SNHL is considerable, present antiviral therapies are teratogenic in themselves, and long-term use of current antiviral drugs by infected children present serious safety concerns. PUBLIC HEALTH RELEVANCE: Congenital cytomegalovirus (CMV) infection is the most common non-genetic cause of sensorineural hearing loss (SNHL) in children, accounting for between 20 and 60% of all SNHL. It is estimated that at least 8000 infants born annually in the US will have congenital CMV-induced SNHL. Since little is presently known about the mechanisms underlying CMV-induced abnormalitites, the objective of this project is to initiate delineation of the molecular pathology of the CMV-induced cochlear abnormalities. The ultimate goal of this research is to identify the molecular mechanisms underlying CMV-induced cochlear dysmorphogenesis and identify cellular targets against which new cochlear-specific, postnatal therapies can be directed to ameliorate SNHL due to congenital CMV infection. In addition, our in vitro model has the added translational value of providing an efficient model system for initial screening of all classes of new tissue-targeted drugs for their ability to preclude CMV-induced pathology. This is clinically important because the prevalence of CMV-induced SNHL is considerable, present antiviral therapies are teratogenic in themselves, and long-term use of current antiviral drugs by infected children present serious safety concerns.