Bartonella Inhibitory Factor for Endothelial Cell Growth

描述（由申请方提供）：巴尔通体的5个种属是人类传染性疾病的新兴病原体。由于它们能够寄生于循环系统内的红细胞和内皮细胞，因此Bartonellose呈现出广泛的心血管表现，包括心内膜炎、杆菌性血管瘤病、紫癜、慢性菌血症和溶血性贫血。巴尔通体寄生微血管内皮细胞的特征在于由我们称为巴尔通体血管生成蛋白（BAP）的细菌蛋白触发的增殖反应。所产生的血管生成产生假瘤形成性血管病变。在我们对BAP的研究中，我们最近发现了一种来自汉赛巴尔通体的抑制性蛋白，该蛋白可显著降低人血管内皮细胞的生长，称为BIF。巴尔通体产生BAP和BIF表明病原体在调节其宿主细胞的生长中起着积极的作用。然而，BAP或BIF的分子性质和机制都是未知的。因此，本项目的长期目标是以汉赛巴尔通体为模型，描述BIF及其作用机制。实现这些目标的具体目标是：1）使用生物化学和分子生物学技术在分子水平上表征BIF，2）通过构建重叠BAP缺失突变体并测定其抑制血管内皮细胞生长的能力，通过绘制其抑制活性所必需的结构域来分析BIF的机制，3）在体外检查BIF和BAP的拮抗作用并在体内评估BIF的血管抑制活性，和4）通过鉴定和表征BIF的同源内皮细胞受体来启动研究以阐明BIF的机制。这些实验将产生有价值的数据的分子性质的一种新的细菌蛋白质，可以调节人类血管内皮细胞的生长，并将有助于阐明的机制，从而血管和假瘤的疾病表现的巴尔通体病是在感染过程中产生。

DESCRIPTION (provided by applicant): Five species of Bartonella are emerging agents of infectious human disease. Because of their ability to parasitize erythrocytes and endothelial cells within the circulatory system, bartonelloses present with a wide array of cardiovascular manifestations including endocarditis, bacillary angiomatosis, peliosis, chronic bacteremia, and hemolytic anemia. Bartonella's parasitism of microvascular endothelial cells is characterized by a proliferative response triggered by a bacterial protein that we have termed Bartonella angiogenic protein (BAP). The resulting angiogenesis generates a pseudoneoplastic vascular lesion. In our work on BAP, we recently discovered an inhibitory protein from Bartonella henselae that significantly reduces the growth of human vascular endothelial cells, termed BIF. Production of BAP and BIF by Bartonella suggests that the pathogen plays an active role in regulating the growth of its host cell. However, neither the molecular nature nor mechanism of BAP or BIF are known. Therefore, the long-term goals of this project are to characterize BIF and its mechanism of action, using Bartonella henselae as a model for the genus. Specific goals to achieve these objectives will: 1) Characterize BIF at the molecular level using biochemical and molecular biological techniques, 2) Analyze BIF's mechanism by mapping domains necessary to its inhibitory activity by creating overlapping BAP deletion mutants and assaying their ability to inhibit vascular endothelial cell growth, 3) Examine BIF and BAP for antagonism in vitro and assess the angiostatic activity of BIF in vivo, and 4) initiate studies to elucidate BIF's mechanism by identifying and characterizing its cognate endothelial cell receptor(s). These experiments will generate valuable data on the molecular nature of a novel bacterial protein that can modulate the growth of human vascular endothelial cells and will help elucidate the mechanism whereby angiomatic and pseudoneoplastic disease manifestations of bartonellosis are generated during infection.