CRYPTOCOCCUS NEOFORMANS--OXIDATIVE KILLING MECHANISMS

新型隐球菌——氧化杀伤机制

• 批准号: 2431643
• 负责人: VISHNU CHATURVEDI
• 金额: $ 10.65万
• 依托单位: WADSWORTH CENTER
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-09-01 至 2002-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2431643
• 关键词: Cryptococcus neoformans; antioxidants; electron spin resonance spectroscopy; gene mutation; genetic strain; host organism interaction; human tissue; laboratory mouse; mannitol; melanins; microorganism immunology; molecular cloning; monocyte; neutrophil; oxidation

DESCRIPTION: (Adapted from Applicant's Abstract) Cryptococcus neoformans causes serious opportunistic disease in patients with AIDS and hematologic malignancies. Phagocytes provide first line of defense against this fungus whereas cell-mediated immunity controls the fungus during systemic disease. It is believed that general defects in monocyte and neutrophil functions combined with impaired T cell responses predispose HIV patients to cryptococcosis. However, it is not know how human phagocytes oxidatively kill C. neoformans and how the fungus foils such attacks. Also, preliminary observations suggest that a distal neutrophil oxidant is fungicidal and that fungal mannitol may protect from oxidative killing. Therefore, the central hypotheses to be tested in this project are: (1) that oxidants distal to superoxide anion (O2-) and hydrogen peroxide (H2O2) are critical in C. neoformans killing and (2) that cryptococcal mannitol acts as an antioxidant. In Specific Aim 1, the investigator will study oxidative killing mechanisms of human monocytes and neutrophils against C. neoformans to identify fungicidal oxidants that may include hydroxyl radicals, hypochlorite, and/or nitric oxide. Specific Aim 2 is to determine whether C. neoformans mannitol functions as an antioxidant in leukocyte interactions by employing C. neoformans natural isolates, mutants deleted in mannitol or over-expressing mannitol. Specific Aim 3 is to compare mannitol with cryptococcal melanin for their antioxidant functions. Mannitol +/- features will be introduced into melanin +/- strains for comparison in oxidant assays. These studies are significant because they will i) characterize leukocyte oxidants that are fungicidal for C. neoformans, ii) define the antioxidant role of C. neoformans mannitol, iii) examine mannitol vis a vis melanin as an antioxidant, iv) suggest unique targets for developing antifungals, and iv) provide methodological basis to study phagocyte oxidants against other pathogenic fungi.

描述：(改编自申请者摘要)新生隐球菌 在艾滋病和血液病患者中引起严重的机会性疾病 恶性肿瘤。吞噬细胞是抵御这种真菌的第一道防线。 而细胞免疫在全身性疾病期间控制真菌。 一般认为单核细胞和中性粒细胞功能缺陷 与受损的T细胞反应相结合使HIV患者更容易 隐球菌病。然而，目前还不知道人类吞噬细胞是如何氧化的 杀死新生葡萄球菌，以及这种真菌是如何抵御这种攻击的。另外，初步的 观察表明，远端的一种中性粒细胞氧化剂具有杀菌作用， 真菌甘露醇可以防止氧化死亡。因此，中央 在这个项目中要检验的假设是：(1)氧化剂远在 超氧阴离子(O2-)和过氧化氢(H2O2)是C. 杀灭新生杆菌和(2)隐球菌甘露醇起到 抗氧化剂。在具体目标1中，研究人员将研究氧化 人单核细胞和中性粒细胞对新生葡萄球菌的杀伤机制 为了鉴定可能含有羟基自由基的杀菌氧化剂， 次氯酸盐和/或一氧化氮。具体目标2是确定是否 新型革兰氏杆菌甘露醇在白细胞相互作用中的抗氧化剂作用 通过使用自然分离的新生葡萄球菌，在甘露醇中删除的突变体或 过度表达甘露醇。具体目标3是将甘露醇与 隐球菌类黑色素具有抗氧化功能。甘露醇+/-特性 将被引入黑色素+/-菌株中进行氧化剂比较 化验。这些研究具有重要意义，因为它们将： 对新生葡萄球菌有杀菌作用的白细胞氧化剂，ii)定义 新型隐形杆菌甘露醇的抗氧化作用，III)甘露醇的检测 黑色素作为一种抗氧化剂，iv)提出了开发的独特靶点 4)为吞噬细胞的研究提供方法学基础。 氧化剂对其他病原真菌的抑制作用。