Bartonella Inhibitory Factor for Endothelial Cell Growth

描述(申请人提供)：五种巴尔通体是传染性人类疾病的新病原体。由于其能够在循环系统内寄生红细胞和内皮细胞，Bartonellos表现出广泛的心血管症状，包括心内膜炎、杆状血管瘤病、皮肤病、慢性菌血症和溶血性贫血。巴尔通体对微血管内皮细胞的寄生以一种我们称之为巴尔通体血管生成蛋白(BAP)的细菌蛋白所触发的增殖反应为特征。由此产生的血管生成会产生假性肿瘤性血管病变。在我们对BAP的研究中，我们最近从亨氏巴尔通体中发现了一种抑制蛋白，称为BIF，它能显著抑制人血管内皮细胞的生长。巴尔通体产生的BAP和BIF表明该病原菌在调节其宿主细胞的生长方面起着积极的作用。然而，BAP或BIF的分子性质和作用机制尚不清楚。因此，本项目的长期目标是利用亨氏巴尔通体作为该属的模型来表征BIF及其作用机制。实现这些目标的具体目标将为：1)利用生物化学和分子生物学技术在分子水平上表征碱性成纤维细胞生长因子；2)通过构建重叠的BAP缺失突变体并检测其抑制血管内皮细胞生长的能力，来分析其抑制活性所必需的结构域；3)在体外检测BIF和BAP的拮抗作用，并评估其体内的血管抑制活性；4)通过鉴定和鉴定其同源内皮细胞受体(S)来研究BIF的作用机制。这些实验将产生一种新的细菌蛋白的分子性质的有价值的数据，这种蛋白可以调节人类血管内皮细胞的生长，并将有助于阐明在感染过程中产生巴尔通氏杆菌病的血管性和假性肿瘤性疾病表现的机制。

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.