NOS2 and arginase in visceral leishmaniasis

内脏利什曼病中的 NOS2 和精氨酸酶

• 批准号: 7009285
• 负责人: Peter C. Melby
• 金额: $ 30.39万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-02-01 至 2010-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7009285
• 关键词: Adenoviridae; Leishmania donovani; arginase; bone marrow transplantation; disease /disorder etiology; enzyme induction /repression; gene expression profiling; genetic regulation; genetic transcription; hamsters; immunopathology; interferon gamma; laboratory mouse; leishmaniasis; leukocyte activation /transformation; macrophage; microorganism immunology; molecular pathology; neutralizing antibody; nitric oxide synthase; skin infection; tissue /cell culture; transfection /expression vector

DESCRIPTION (provided by the applicant): Syrian hamsters recapitulate the two major forms of infection with Leishmania donovani seen in man. After systemic infection, these animals develop a progressive disease that mimics the clinical-pathological features of human VL. However, hamsters infected in the skin control the infection locally, and acquire immunity to systemic challenge, akin to sub-clinically infected individuals who develop immunity against visceral disease. These two broad features prompted us to initiate studies to dissect the molecular immunopathogenesis of L. donovani infection in this unique animal model. In preliminary studies we found that during progressive disease in the hamster model of VL, a Type 1 T cell response is mounted, but is ineffective and accompanied by undetectable NOS2 expression. Furthermore, in contrast to mouse macrophages, IFN-gamma-activated hamster macrophages do not produce detectable NO and are unable to control intracellular infection. These distinctions between hamsters and mice provide the impetus to directly compare and contrast mechanisms of macrophage activation/deactivation in these species, with particular focus on the NOS2-arginase metabolic pathways. We will extend in vitro findings to in vivo proof-of-principle studies in the hamster, again with the focus on the role of the NOS2-arginase metabolic pathways in resistance to disease and protective immunity. We will approach the role of NOS2 and arginase in infection with L donovani from two opposite, but complementary directions. In Specific Aims 1 and 2 we will determine the role of NOS2 and arginase expression in the pathogenesis of visceral infection through in vitro studies of infected hamster and mouse macrophages, and in vivo studies of systemically infected hamsters. Specific Aim 1 will test the hypothesis that the impaired capacity of hamster macrophages to control L. donovani infection is a result of the hypo-responsiveness of NOS2 to IFN-gamma-mediated activation, and that this NOS2 hyporesponsiveness is mediated through transcriptional mechanism(s). Specific Aim 2 will test the hypothesis that the impaired NOS2 expression sets the stage for an arginase-dominated alternative activation or deactivation pathway in infected hamster or human macrophages, which leads to impaired parasite killing. In Specific Aim 3 we will determine if the control of primary cutaneous infection and protection against secondary visceral challenge following acquisition of immunity is mediated by a reversal of the default toward low NOS2 and high arginase expression. We hypothesize that NOS2-independent mechanisms contribute to resistance and we will break new ground in the discovery of a gene expression profile that characterizes resistance to primary and secondary infection in the hamster. These studies in the hamster will fill a knowledge gap by defining mechanisms of disease and immunity that are strikingly different from those of the murine model.

描述（由申请人提供）：叙利亚仓鼠用人观察到的利什曼原虫Donovani概括了两种主要形式的感染形式。在全身感染后，这些动物发展出一种进行性疾病，该疾病模仿了人VL的临床病理特征。然而，在皮肤中感染的仓鼠控制着当地的感染，并获得对系统性挑战的免疫力，类似于受到抗内脏疾病免疫力的临界感染的个体。这两个广泛的特征促使我们启动研究，以在这种独特的动物模型中剖析多诺瓦尼乳杆菌感染的分子免疫发病。在初步研究中，我们发现，在VL的仓鼠模型中进行性疾病期间，安装了1型T细胞反应，但无效，并且伴随着无法检测到的NOS2表达。此外，与小鼠巨噬细胞相比，IFN-gamma激活的仓鼠巨噬细胞不会产生可检测到的NO，并且无法控制细胞内感染。仓鼠和小鼠之间的这些区别提供了直接比较这些物种中巨噬细胞激活/失活的对比机制的动力，尤其侧重于NOS2-精氨酸酶代谢途径。我们将在仓鼠中扩展体外发现到体内原则研究，再次侧重于NOS2-精氨酸酶代谢途径在抵抗疾病和保护性免疫中的作用。我们将从两个相反但互补的方向从l donovani感染NOS2和精氨酸酶在感染中的作用。在特定的目标1和2中，我们将通过体外研究受感染的仓鼠和小鼠巨噬细胞的体外研究以及对系统感染的仓鼠的体内研究来确定NOS2和精氨酸表达在内脏感染的发病机理中的作用。具体的目标1将检验以下假设：仓鼠巨噬细胞控制多诺瓦乳杆菌感染的能力受损是NOS2对IFN-GAMMA介导的激活的低反应性的结果，并且该NOS2低温性是​​通过转录机制介导的。具体目标2将检验以下假设：受损的NOS2表达为精氨酸酶主导的替代激活或失活途径奠定了阶段，这会导致寄生虫杀死受损。在特定的目标3中，我们将确定获得免疫力后的原发性皮肤感染和防止次要内脏挑战的控制是否是由对低NOS2和高精氨酸酶表达的默认值的逆转介导的。我们假设NOS2独立的机制有助于抗药性，并且在发现基因表达谱的新基础上，该基因表达谱是对仓鼠中原发性和继发感染的抗性的。仓鼠中的这些研究将通过定义与鼠模型的疾病和免疫力的机制来填补知识差距。