Mechanism of growth stimulatory effect of vascular endothelial cells by Bartonella henselae.

本实验对汉赛巴尔通体刺激血管内皮细胞生长的机制进行了研究，取得了以下结果：1。B，henselae与人脐静脉内皮细胞（HUVECs）之间的相互作用：将B.henselae ATCC 49882（10^7 CFU/ml）与HUVECs共培养，并通过MTT测定来估计HUVECs的生长。活B.henselae对HUVECs的增殖有明显的促进作用，且呈剂量依赖性，这种促进作用对血管内皮细胞具有特异性。在兔或狗的内皮细胞中也观察到类似的生长促进作用.促进生长的活性成分和机制：紫外线照射或热处理杀死的汉赛B.henselae使其刺激活性消失，表明这种作用是由活菌的某些作用而不仅仅是细菌细胞的存在所表现的。为了研究直接接触的作用，通过膜过滤器（Millicell-CM）从HUVEC分离活的汉赛B.henselae。即使在这种条件下，也观察到HUVECs增殖刺激作用。与汉赛B感染细胞相比，HUVECs的形态学变化不明显。此外，我们分离出一种无纤毛的B.henselae菌株，该菌株不能附着和进入内皮细胞。无毛株具有与有毛株相同的刺激HUVECs增殖的能力。本研究结果提示，汉赛B.henselae可能产生并分泌某些血管生成因子，目前该血管生成因子的纯化和特性研究正在进行中.体内研究：将汉赛B.henselae接种于鸡胚、小鼠和豚鼠的绒毛尿囊膜（皮下或皮内途径），但在动物中未观察到血管生成性病变。

We studied on the mechanism of growth stimulatory effect of vascular endothelial cells by Bartonella henselae, and obtained the following results ;1. Interaction between B, henselae and human umbilical vein endothelial cells (HUVECs) : B.henselae ATCC 49882 (10^7 CFU/ml) was cocultivated with HUVECs, and the growth of HUVECs was estimated by MTT assay. The proliferation of HUVECs cocultivated with live B.henselae was enhanced in inoculated-bacterial dose dependent manner, and the stimulatory effect was specific for vascular endothelial cells. Similar growth enhancement effect was also observed in endothelial cells from rabbits or dogs.2. Active component and mechanism of growth enhancement : B.henselae killed by UV irradiation or heat treatment abolished its stimulatory activity, suggesting that the effect was exhibited by some action of live bacteria, not only by the existence of bacterial cells. To investigate the role of direct contact, live B.henselae were separated from HUVECs by membrane filter (Millicell-CM). Even under this condition, the HUVECs proliferation stimulating effect was observed. However, the morphological changes of HUVECs were not apparent compared to B.henselae infected cells. Furthermore, we isolated a nonpiliated B.henselae strain which was unable to attach to and entry into endothelial cells. The nonpiliated strain possessed the ability to stimulate the proliferation of HUVECs same as piliated strain. Our results suggested that B.henselae might produce some angiogenic factor(s) and secrete it. Further study is currently under way to purify and characterize this angiogenic factor.3. In vivo study : B.henselae was inoculated into chorioallantoic membrane of embryonated eggs, mice and guinea pigs (subcutaneous or intradermal routs), however, no angiogenic lesion was observed in the animals.