Bacterial membrane vesicles as modulators of adverse pregnancy outcomes

B组链球菌(GBS)存在于泌尿生殖道，占孕妇绒毛膜羊膜炎、早产、死产、新生儿败血症和脑膜炎的35%。GBS感染发生在胎盘膜侵入后的子宫内，或在分娩期间因阴道内吸入物而发生。我们先前的研究表明，在新生儿疾病病例中，特定的GBS基因型比具有更强的感染母胎界面细胞的能力的孕妇更常见。然而，在我们对不同的GBS菌株持续定植和/或侵入胎盘膜的机制的理解上存在着严重的差距。我们预计表型变异及其对宿主反应的影响是一个重要但研究不足的贡献因素，并代表了这一提议的重点。我们的初步数据显示，不同的GBS菌株分泌数量、大小和蛋白质含量不同的胞外膜小泡(MVS)，这些MVS在体外诱导巨噬细胞的炎性细胞因子反应。我们还发现，来自两个不同GBS毒株的MVS含有丰富的蛋白质，这些蛋白质被归类为已知的和新的GBS毒力因子，表明MVS在GBS的发病机制中发挥了作用。虽然最近在GBS中描述了MVS，但只有一种罕见基因的对照株被研究。因此，我们建议：1)确定人类妊娠组织中GBS MVS对宿主反应的影响；2)确定MVS对妊娠小鼠宿主反应和胎儿结局的影响；3)确定GBS MVS的蛋白质含量。我们将对不同基因类型的侵袭性和非侵袭性菌株的MVS含量进行表征，并对从母胎界面回收的原始细胞以及怀孕小鼠感染后的宿主反应进行分类。我们预测，来自侵袭性GBS菌株而不是共生菌株的MVS将触发炎症反应，从而导致胎儿或新生儿损伤。在短期内，我们将确定MVS在炎症反应、不良妊娠结局和毒力方面所起的作用。我们的长期目标是发现与感染、疫苗靶标和递送系统相关的新生物标记物，这些标记物可能会影响由GBS和其他具有类似生活方式的病原体引起的疾病。

Group B Streptococcus (GBS) resides in the genitourinary tract and colonizes up to 35% of pregnant women contributing to chorioamnionitis, preterm birth, stillbirth, and neonatal sepsis and meningitis. GBS infections occur in utero following invasion of the placental membranes or during childbirth upon aspiration within the vaginal canal. Our prior studies have shown that specific GBS genotypes are more common among neonatal disease cases than pregnant mothers with a superior ability to infect cells at the maternal-fetal interface. However, there are critical gaps in our understanding of the mechanisms that different GBS strains use to persistently colonize and/or invade the placental membranes. We expect that phenotypic variation and its impact on host responses is an important yet understudied contributor to consider and represents the focus of this proposal. Our preliminary data show that distinct GBS strains secrete extracellular membrane vesicles (MVs) that vary in quantity, size and protein content and that these MVs elicit inflammatory cytokine responses from macrophages in vitro. We also found that MVs from two different GBS strains contained differentially abundant proteins that were classified as known and novel GBS virulence factors, suggesting that MVs play a role in GBS pathogenesis. Although MVs were recently described in GBS, only one control strain of a rare genotype was studied. Consequently, we propose to: 1) Determine the influence of GBS MVs on host response in human gestational tissues; 2) Determine the influence of MVs on host response and fetal outcome in pregnant mice; and 3) Ascertain the protein content of GBS MVs. We will characterize the content of MVs from both invasive and non-invasive strains of varying genotypes and classify host responses from primary cells recovered from the maternal-fetal interface as well as following infection of pregnant mice. We predict that MVs from the invasive GBS strains and not the commensal strains will trigger inflammatory responses that contribute to fetal or neonatal injury. In the short term, we will determine the role that MVs play in inflammatory responses, adverse pregnancy outcomes and virulence. Our long-term goal is to discover novel biomarkers associated with infection, vaccine targets and delivery systems that can potentially impact diseases caused by GBS and other pathogens with similar lifestyles.