Anaplasma - B. burgorferi/endothelijm interactions

描述(申请人提供)：莱姆病，由鹿传播的伯氏疏螺旋体引起，其症状包括皮肤感染和血液侵入心脏、关节和神经系统。人类粒细胞无形体病(HGA)是由吞噬细胞无形体引起的，这是一种中性粒细胞立克次体，也由鹿扁虱传播。临床研究、血清学研究和动物研究越来越多地表明，与吞噬弧菌混合感染可能导致莱姆病的严重程度和并发症。大多数联合感染的研究都集中在吞噬细胞门氏菌对伯氏杆菌的免疫调节反应。然而，扁虱传播的病原体之间的一个共同联系是获得血液以进行传播和穿透血管壁的能力。初步研究表明，伯氏杆菌与内皮细胞的结合和通过在一定程度上是由宿主基质金属蛋白酶(MMPs)介导的，伯氏杆菌和嗜中性粒细胞感染的伯氏杆菌与内皮细胞共孵育可促进伯氏杆菌的移行。吞噬细胞感染的中性粒细胞在血小板选择素糖蛋白配体1(CD162)和L选择素(CD62L)黏附分子表达显著丧失后，释放趋化因子并失去与激活的内皮细胞黏附的能力。基质金属蛋白酶抑制剂逆转L-选择素的丢失，只有二价阳离子螯合剂逆转PSGL-1表面的脱落。这些数据表明MMPs和一种新的脱落酶参与了这一过程。因此，新的PSGL-1脱落酶或趋化因子在伯氏杆菌迁徙和传播中的协同作用被提出。这项研究的假设是吞噬弧菌引起的中性粒细胞功能变化，包括趋化因子或基质金属蛋白酶的释放，增强了伯氏杆菌通过血管屏障的天然能力。我们建议：(1)量化和定义吞噬细胞增强型伯氏杆菌在血管和脑微血管内皮细胞间迁移的动力学；以及(2)定义特定的伯氏杆菌移行促进因子，如MMPs、趋化因子或吞噬细胞感染细胞的其他生物活性产物。从拟议的研究中获得的结果将确定在伯氏杆菌的传播中是否存在合并感染的独特的非免疫学作用。解释增强的步骤的阐明可能允许对莱姆病、HGE和混合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.