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

描述(申请人提供)：先天性免疫系统通过微生物的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相互作用来识别病原体。已知的12个Toll样受体中的每一个都结合了一组不同的致病标志物，从而总共识别了大量的微生物。这种参与只通过两条主要的细胞内途径激活和诱导炎症介质，即髓系分化因子88(MyD88)依赖的信号通路和MyD88非依赖的信号通路。本研究的目的是验证一种假说，即通过依赖MyD88的信号转导通路传递的Toll样受体信号是病原体诱导早产的重要且可改变的介质。这一假设将在小鼠模型中进行验证，首先(具体目标#1)使用肽聚糖(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有关的革兰氏阳性微生物)表征MyD88依赖和独立的通路在病原体引产中的作用。缺乏TLR-2或MyD88的突变小鼠将被用来确定这些蛋白在病原体引产中的作用。在特定的目标#2中，将测试MyD88(一种称为MyD88s的剪接变体)的负调控因子防止依赖于MyD88的早产的能力。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MyD88运送到妊娠室。最后，在具体目标#3中，我们将利用自本申请首次提交以来的一项新观察，即大肠杆菌引产对MyD88具有排他性要求。对母亲和胎儿在大肠杆菌引产信号中各自作用的剖析将使用孕妇和胎儿MyD88基因在信息方面不同的怀孕进行。公共卫生相关性：在美国，早产影响了超过12%的分娩，即每年约48万名婴儿，在发达国家，早产仍然是导致新生儿疾病和死亡的最重要原因。50%或更多的原因不明的早产病例与感染有关。在美国，早产的发生率继续上升，这一事实反映出我们对分娩的原因和机制的了解仍然不足。

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.