Invasion of brain endothelial cells by C. neoformans

新型隐球菌对脑内皮细胞的侵袭

• 批准号: 7084526
• 负责人: AMBROSE Y JONG
• 金额: $ 24.07万
• 依托单位: CHILDREN'S HOSPITAL OF LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-09-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7084526
• 关键词: CD44 molecule; Cryptococcus neoformans; blood brain barrier; brain cell; cell adhesion; chemical structure function; disease /disorder model; fungal genetics; fungal proteins; glucuronosyltransferase; host organism interaction; hyaluronate; infectious meningitis; intermolecular interaction; laboratory mouse; molecular pathology; mycosis; neuropathology; transcytosis

DESCRIPTION (provided by applicant): The long-term goal of this project is to dissect the pathogenesis of Cryptococcus meningitis. In recent years infection by Cryptococcus neoformans has increased considerably, particularly in immunocomprised individuals and AIDS patients. This pathogen has a predilection to the brain, resulting in devastating meningoencephalitis. It is unclear how C. neoformans traverses across the blood-brain barrier and causes the central nervous system infection. We propose to investigate the mechanisms of C. neoformans invasion in human brain microvascular endothelial cells (HBMEC), which constitute the blood-brain barrier. We have established in vitro and in vivo BBB models for the pathogen invasion studies. Using these model systems, we found that C. neoformans, either treated with hyaluronidase or with 4-methylumbelliferone (a hyaluronan synthase inhibitor) substantially reduced its binding ability to HBMEC. In contrast, exogenous hyaluronan was found to stimulate C. neoformans binding activity. The CPS1 protein sequence shares homology with hyaluronan synthase. The cpsl-disrupted strain lost its hyaluronan on the cell surface, and also substantially reduced its binding activity to HBMEC. Finally, anti-CD44 blocking antibody could neutralize the interaction between C. neoformans and HBMEC. Taken together, our preliminary studies suggested that the C. neoformans capsule component, hyaluronan, and HBMEC CD44 were involved in the invasion process. In this proposal, we will test the hypothesis that C. neoformans hyaluronan and HBMEC CD44 are crucial for C. neoformans pathogenesis. We will explore the mechanisms of C. neoformans invasion to HBMEC by the following Aims: First, we will examine the role of CPS1 in hyaluronan synthesis and C. neoformans invasion. Second, we will determine how C. neoformans hyaluronan contribute to the binding and invasion of HBMEC. Third, we will determine whether and how HBMEC CD44 functions as a HA receptor during C. neoformans invasion. The proposed approach will allow us to determine the role(s) of the crucial C. neoformans component, hyaluronan, and host responses during invasion. The information derived from this proposal should be helpful in the development of novel strategies to prevent C. neoformans meningitis and its associated morbidity.

描述（由申请人提供）：该项目的长期目标是剖析隐球菌脑膜炎的发病机制。近年来，新型隐球菌感染显着增加，特别是在免疫功能低下的个体和艾滋病患者中。这种病原体偏爱大脑，导致毁灭性的脑膜脑炎。目前尚不清楚新型隐球菌如何穿过血脑屏障并引起中枢神经系统感染。我们打算研究新型隐球菌侵入构成血脑屏障的人脑微血管内皮细胞（HBMEC）的机制。我们建立了用于病原体入侵研究的体外和体内BBB模型。使用这些模型系统，我们发现用透明质酸酶或 4-甲基伞形酮（透明质酸合酶抑制剂）处理的新型隐球菌显着降低了其与 HBMEC 的结合能力。相反，发现外源透明质酸可刺激新型隐球菌结合活性。 CPS1 蛋白序列与乙酰透明质酸合酶具有同源性。 cpsl 破坏的菌株在细胞表面失去了透明质酸，并且还大大降低了其与 HBMEC 的结合活性。最后，抗CD44阻断抗体可以中和新型隐球菌和HBMEC之间的相互作用。综上所述，我们的初步研究表明，新型隐球菌胶囊成分、透明质酸和 HBMEC CD44 参与了侵袭过程。 在本提案中，我们将检验以下假设：新型隐球菌透明质酸和 HBMEC CD44 对于新型隐球菌发病机制至关重要。我们将通过以下目的探讨新型隐球菌入侵HBMEC的机制：首先，我们将研究CPS1在透明质酸合成和新型隐球菌入侵中的作用。 其次，我们将确定新型隐球菌透明质酸如何促进 HBMEC 的结合和侵袭。 第三，我们将确定 HBMEC CD44 在新型隐球菌入侵期间是否以及如何作为 HA 受体发挥作用。所提出的方法将使我们能够确定关键的新型隐球菌成分透明质酸和入侵过程中宿主反应的作用。从该提案中获得的信息应有助于制定预防新型隐球菌脑膜炎及其相关发病率的新策略。