Toll-like receptor signaling in the pathogenesis and prevention of prematurity

描述（由申请人提供）：先天免疫系统通过微生物分子成分与宿主细胞上称为toll样受体（TLRs）的特殊模式识别分子的相互作用来识别病原体。已知的12种toll样受体中的每一种都与一组不同的致病标记物相关，因此可以识别各种各样的微生物。这种参与仅通过两种主要的细胞内通路导致炎症介质的激活和诱导，即骨髓分化因子88 （MyD88）依赖性和MyD88非依赖性信号通路。本研究的目的是验证通过myd88依赖性信号转导通路的toll样受体信号是病原体诱发早产的必要和可改变的介质这一假设。这一假设将在小鼠模型中进行验证，首先（Specific Aim #1）利用肽聚糖（一种来自革兰氏阳性细菌细胞壁的TLR-2配体）和B组β溶血性链球菌（GBBS，一种与早产和新生儿败血症相关的革兰氏阳性细菌）表征myd88依赖性和非依赖性途径在病原体诱导分娩中的作用。缺乏TLR-2或MyD88的突变小鼠将被用来确定这些蛋白质在病原体诱导的分娩中的作用。在专项目标#2中，将检测MyD88负调节因子（一种被称为MyD88的剪接变体）预防MyD88依赖性早产的能力。一种新的细胞内传递外源蛋白（tat融合蛋白）的方法将被用于将MyD88s运送到妊娠室。最后，在Specific Aim #3中，我们将利用自首次提交该申请以来所做的新观察，即大肠杆菌诱导的分娩对MyD88具有排他要求。研究人员将利用母体和胎儿MyD88基因型不同的妊娠情况，解剖母体和胎儿在大肠杆菌引产信号传导中的各自作用。公共卫生相关性：在美国，早产影响了超过12%的分娩，或每年约48万名婴儿，并且仍然是发达国家新生儿疾病和死亡的最重要原因。50%或更多原因不明的早产病例与感染有关。在美国，早产的发生率持续上升，这一事实反映了我们对分娩的原因和机制的知识的持续不足。

DESCRIPTION (provided by applicant): The innate immune system recognizes pathogens via the interaction of molecular constituents of microorganisms with specialized pattern recognition molecules on host cells known as toll-like receptors (TLRs). Each of the 12 known toll-like receptors engages a different set of pathogenic markers, thereby recognizing in total a large variety of microorganisms. This engagement leads to activation and induction of inflammatory mediators via only two major intracellular pathways, known as the myeloid differentiation factor 88 (MyD88)-dependent and MyD88-independent signaling pathways. The objective of this proposal is to test the hypothesis that toll-like receptor signaling via the MyD88-dependent signal transduction pathway is an essential and modifiable mediator of pathogen-induced preterm labor. This hypothesis will be tested in a mouse model by first (Specific Aim #1) characterizing the roles of the MyD88-dependent and -independent pathways in pathogen-induced labor using peptidoglycan (a TLR-2 ligand derived from Gram positive bacterial cell walls) and group B beta-hemolytic streptococcus (GBBS, a Gram positive organism associated with preterm labor and neonatal sepsis). Mutant mice lacking either TLR-2 or MyD88 will be used to define the roles of these proteins in pathogen-induced labor. In Specific Aim #2 the capacity of a negative regulator of MyD88 (a splice variant known as MyD88s) to prevent MyD88-dependent preterm birth will be tested. A new method of delivering exogenous proteins intracellularly (TAT-fusion proteins) will be used to ferry MyD88s into the gestational compartment. Finally, in Specific Aim #3 we will take advantage of a novel observation made since the first submission of this application, namely that E. coli-induced labor has an exclusive requirement for MyD88. Dissection of the respective roles of mothers and fetuses in signaling for E. coli induced labor will be conducted using pregnancies in which maternal and fetal MyD88 genotypes differ in informative ways. PUBLIC HEALTH RELEVANCE: Preterm birth affects over 12% of all deliveries in the U.S., or approximately 480,000 babies annually, and continues to be the most important cause of neonatal illness and death in developed countries. Fifty percent or more of unexplained cases of preterm birth are related to infection. The incidence of preterm delivery continues to rise in the U.S., a fact that reflects continuing deficiencies in our knowledge of the causes and mechanisms of parturition.