Anaplasma - B. burgdorferi /endothelium interactions

描述（由申请人提供）：由鹿蜱传播的螺旋体伯氏疏螺旋体引起的莱姆病的表现包括皮肤感染到血液侵入心脏、关节和神经系统。人粒细胞无形体病（HGA）是由嗜吞噬细胞无形体引起的，这是一种中性粒细胞立克次体，也由鹿蜱传播。临床调查、血清学研究和动物研究越来越多地表明，与嗜吞噬胞芽胞杆菌合并感染可能导致莱姆病的严重程度和并发症。大多数合并感染研究集中在单胞菌对伯氏疏螺旋体的吞噬细胞调节免疫反应上。然而，蜱传播病原体之间的共同联系是通过血液传播和通过血管壁的能力。初步研究表明，伯氏疏螺旋体与内皮细胞的结合和传代在一定程度上是由宿主基质金属蛋白酶（MMPs）介导的，伯氏疏螺旋体和吞噬细胞感染的中性粒细胞与内皮细胞共孵养可增强伯氏疏螺旋体的转运。在血小板选择素糖蛋白配体(PSGL)-1 （CD162）和l -选择素（CD62L）粘附分子表达显著丧失后，吞噬细胞感染的中性粒细胞释放趋化因子并失去粘附活化内皮细胞的能力。虽然MMP抑制剂可以逆转l -选择素的丢失，但只有二价阳离子螯合剂才能逆转表面PSGL-1的脱落。数据表明MMPs的参与和一个新的数据库。因此，新的PSGL-1脱落酶或趋化因子在伯氏疏螺旋体的迁移和传播中具有协同作用。本研究的假设是，嗜吞噬胞杆菌引发的功能性中性粒细胞变化，包括趋化因子或MMP的释放，增强了伯氏疏螺旋体穿越血管屏障的天然能力。我们建议：(1)量化和定义嗜吞噬芽胞杆菌增强伯氏疏螺旋体跨血管和脑微血管内皮细胞迁移的动力学；(2)确定特定的伯氏疏螺旋体迁移增强因子，如MMPs、趋化因子或其他吞噬细胞感染细胞的生物活性产物。从拟议的研究中获得的结果将确定在伯氏疏螺旋体的传播中是否存在独特的非免疫作用。解释增强的步骤的阐明可能允许对莱姆病，HGE和合并感染的毒力机制进行更深入的基础和临床研究。

DESCRIPTION (provided by applicant): The manifestations of Lyme disease, caused by the deer tick-transmitted spirochete, Borrelia burgdorferi, range from skin infection to bloodstream invasion into the heart, joints, and nervous system. Human granulocytic anaplasmosis (HGA) is caused by Anaplasma phagocytophilum, a rickettsia of neutrophils that is also transmitted by the deer tick, Ixodes scapularis. Clinical investigations, serologic studies, and animal studies increasingly suggest that coinfection with A. phagocytophilum may contribute to severity and complications of Lyme disease. Most coinfection studies focus on A. phagocytophilum-modulated immune response to B. burgdorferi. However, a common link between tick-transmitted pathogens is access to blood for dissemination and the ability to pass through blood vessel walls. Preliminary studies show that B. burgdorferi binding and passage through endothelial cells is in part mediated by host matrix metalloproteases (MMPs), and that coincubations of B. burgdorferi and A. phagocytophilum-infected neutrophils with endothelial cells enhance transmigration of B. burgdorferi. A. phagocytophilum-infected neutrophils release chemokines and lose the ability to adhere to activated endothelial cells after significant loss of platelet selectin glycoprotein ligand (PSGL)-1 (CD162) and L-selectin (CD62L) adhesion molecule expression. While MMP inhibitors reverse L-selectin loss, only divalent cation chelators reverse shedding of surface PSGL-1. The data suggest the involvement of MMPs and a novel sheddase. Thus, a synergistic role for the novel PSGL-1 sheddase or chemokines is suggested in B. burgdorferi transmigration and dissemination. The hypothesis of the proposed research is that functional neutrophil changes triggered by A. phagocytophilum, including chemokine or MMP release, enhance the native ability of B. burgdorferi to transit across vascular barriers. We propose to: (1) quantify and define the kinetics of A. phagocytophilum enhanced B. burgdorferi transmigration across vascular and brain microvascular endothelial cells; and (2) define the specific B. burgdorferi transmigration enhancing factors such as MMPs, chemokines, or other biologically active products of A. phagocytophilum-infected cells. The results obtained from the proposed study will establish whether a distinctive non-immunologic role for coinfection exists in the dissemination of B. burgdorferi. The elucidation of the steps that explain the enhancement may allow for more intensive basic and clinical investigation into mechanisms of virulence for Lyme disease, HGE, and coinfections.