Mechanisms regulating fetal membrane and neutrophil responses to infection

摘要/摘要 绒毛膜羊膜炎--胎膜炎症--以中性粒细胞渗透为特征， 这是早产的一个主要风险因素。即使在没有早产的情况下，绒毛膜羊膜炎也可能对 胎儿。尽管细菌感染、绒毛膜羊膜炎和早产之间有很强的相关性，但 其中涉及的机制还不完全清楚。通过表达先天免疫模式识别 受体(PRR)、Toll样受体(TLRs)和Nod样受体(NLRs)，Fm有逃避和 防止感染。然而，根据信号和调节的性质，这些保护性 免疫机制可能会造成炎症环境，从而导致病理改变。特别是，IL-8是一种 主要的中性粒细胞趋化因子和炎症性小体介导的IL-1b是组织损伤和 早产的中介人。我们发现绒毛膜室是FM、IL-8和IL-8的主要部位。 细菌脂多糖(LPS)、肽多聚糖(PDG)和胞壁二肽对1B产生的响应 (MDP)分别激活TLR4、TLR2和NOD2。而TLR和NLR可以直接激活 导致炎症细胞因子/趋化因子产生的信号通路，还有更多的可能性 对这些过程和产生的响应的类型进行复杂的调制、调节和微调， 尤其是IL-1b。这项授权侧重于顺序激活两个或更多PRR的要求 在通过新的中间体暴露于细菌触发物的FM中。一个非经典的microRNAs家族(MiRs) 激活单链RNA传感器TLR7和TLR8，以引发炎症反应。这些MIR也可以是 在外体中携带，并在靶细胞中传递到TLR7或TLR8。我们的初步数据支持这一概念 TLR8激活miR-146a-3p可能作为一种新的中间信号驱动FM趋化和 对细菌TLR和NLR激动剂的炎症反应。我们也有初步数据表明， 含有TLR8激活miRs的FM来源的外切体可激活中性粒细胞并释放中性粒细胞 胞外陷阱。最后，我们发现FM组织和循环外体激活的TLR8-miR-146a-3p是 在早产妇女中升高。基于此，我们的中心假设是TLR8激活的miRs 介导FM趋化IL-8和炎性小体介导的炎性IL-1b对细菌的反应 触发，并通过它们的释放和交付通过外体活跃的母体中性粒细胞。这条线索 导致母胎界面发炎，增加绒毛膜羊膜炎的风险。为了测试这一点，我们的 具体目标是确定是否： 目的1.TLR8激活的miRs在暴露于细菌触发物后介导调频趋化IL-8反应。 目的2.TLR8激活的miRs参与了FM炎症体的激活和炎性IL-1b的产生。 目的3.含有TLR8激活miRs的FM外切体可诱导中性粒细胞活化。

Summary/Abstract Chorioamnionitis - inflammation of the fetal membranes (FM) - is characterized by neutrophil infiltration and is a major risk factor for preterm birth. Even in the absence of prematurity, chorioamnionitis can be detrimental to the fetus. Despite a strong association between bacterial infection, chorioamnionitis, and preterm birth, the mechanisms involved are not fully understood. Through expression of the innate immune pattern recognition receptors (PRR), Toll-like receptors (TLRs) and Nod-like receptors (NLRs), FMs have strategies to evade and protect against infection. However, depending upon the nature of signaling and regulation, these protective immune mechanisms may create an inflammatory milieu that can contribute to pathology. In particular, IL-8 is a major neutrophil chemoattractant and inflammasome-mediated IL-1b is a major inducer of tissue injury and mediator of preterm birth. We have found that the chorionic compartment is the primary site of FM IL-8 and IL- 1b production in response to bacterial lipopolysaccharide (LPS), peptidoglycan (PDG), and muramyl dipeptide (MDP) which activate TLR4, TLR2, and Nod2, respectively. While TLRs and NLRs can directly activate signaling pathways leading to inflammatory cytokine/chemokine production, there is the potential for far more complex modulation, regulation, and fine-tuning of these processes and the type of responses generated, particularly for IL-1b. This grant focusses on the requirement of two or more PRRs to be activated sequentially in FMs exposed to bacterial triggers via novel intermediates. A non-classical family of microRNAs (miRs) activate the ssRNA sensors, TLR7 and TLR8, to elicit an inflammatory response. These miRs can also be carried in exosomes and delivered to TLR7 or TLR8 in target cells. Our preliminary data supports the concept that TLR8-activating miR-146a-3p may acts as a novel intermediate signal that drives FM chemotactic and inflammatory responses to bacterial TLR and NLR agonists. We also have preliminary data demonstrating that FM-derived exosomes containing TLR8-activating miRs trigger neutrophil activation and release of neutrophil extracellular traps. Finally, we found that FM tissue and circulating exosomal TLR8-activating miR-146a-3p is elevated in women with preterm birth. Based on this, our central hypothesis is that TLR8-activating miRs mediate FM chemotactic IL-8 and inflammasome-mediated inflammatory IL-1b in response to bacterial triggers, and through their release and delivery via exosomes active maternal neutrophils. This leads to inflammation at the maternal-fetal interface, increasing the risk for chorioamnionitis. To test this, our specific aims are to determine if: Aim 1. TLR8-activating miRs mediate a FM chemotactic IL-8 response after exposure to bacterial triggers. Aim 2. TLR8-activating miRs contribute to FM inflammasome activation and inflammatory IL-1b production. Aim 3. FM exosomes containing TLR8-activating miRs induce neutrophil activation.