Mechanisms of PVL-induced Acute Lung Injury

PVL引起的急性肺损伤的机制

• 批准号: 8464624
• 负责人: Binh An Diep
• 金额: $ 38.35万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-06-15 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8464624
• 关键词: Accounting; Active Immunization; Acute; Acute Lung Injury; Alveolar; Antibodies; Attenuated; Cells; Cessation of life; Chemotactic Factors; Communities; Complement; Conflict (Psychology); Cytolysis; Cytoplasmic Granules; Data; Development; Disease; Epidemic; Exotoxins; FOLH1 gene; Genes; Hemolysin; Human; Immunity; Individual; Infection; Inflammation; Inflammatory Response; Injury; Interleukin-8; Knowledge; Leucocidin; Lung; Lung Inflammation; Measures; Mediating; Modeling; Mus; Necrosis; Oryctolagus cuniculus; Panton-Valentine leukocidin; Parents; Passive Immunization; Pathogenesis; Patients; Permeability; Pharmaceutical Preparations; Phenols; Play; Pneumonia; Predisposition; Prevention approach; Process; Prophylactic treatment; Pulmonary Edema; Recruitment Activity; Relative (related person); Rodent; Role; Staphylococcus aureus; Testing; Therapeutic Intervention; Time; Tissues; Toxin; Virulence; Virulent; base; chemokine; cytotoxic; cytotoxicity; defined contribution; design; gene complementation; human disease; immunogenicity; lung injury; methicillin resistant Staphylococcus aureus; mortality; mutant; neutrophil; novel therapeutic intervention; pandemic disease; prevent; public health relevance; research study; synergism; treatment strategy

DESCRIPTION (provided by applicant): Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), especially the pandemic USA300 clone, is associated with severe infections and high mortality rates, particularly in patients with pneumonia. USA300 produces Panton-Valentine leukocidin (PVL), a potent exotoxin that lyses polymorphonuclear leukocytes (PMNs). It has been generally assumed that PVL accounts for hypervirulence of USA300 and has a key role in pathogenesis of necrotizing pneumonia, but data from rodent infection models are conflicting. Rodent PMNs are less susceptible than human PMNs to PVL cytotoxicity, which may account for the inconclusive results. Rabbit and human PMNs are similar in their susceptibility to PVL. Postulating that PMNs play a role in the tissue destructive process (and therefore susceptibility of this target cell to PVL effects matters), we developed a rabbit model of pneumonia. In this model, an isogenic PVL-negative USA300 mutant was attenuated in its capacity to cause lethal pneumonia compared to the PVL-positive parent; virulence was fully restored in the PVL-complemented mutant. Infection with the PVL-positive strain was remarkably similar to the human disease. Airspace instillation of purified PVL alone induced rapid onset of acute lung injury and lung inflammation. The overall objective of this project is to determine the mechanisms of PVL-induced acute lung injury, lung inflammation and lethal necrotizing pneumonia. Four specific aims are proposed. Aim 1. To determine the role of host inflammatory response in PVL-induced necrotizing pneumonia. We hypothesize that PVL-induced acute lung injury is mediated by PMNs. To test this hypothesis, we will determine whether blocking interleukin 8, the principal chemokine that recruits PMNs into the lung, attenuates PVL-induced acute lung injury and lung inflammation. Aim 2. To determine whether PVL and related bicomponent toxins, leukocidin (LukED) and -haemolysin (HlgABC), individually or synergistically induce acute lung injury and lung inflammation. We will investigate whether deletion of the lukED and hlgABC genes attenuates virulence; whether gene complementation restores virulence; and determine the levels of LukED and HlgABC expression during infection. Potential synergism among PVL, LukED and HlgABC in inducing acute lung injury and lung inflammation also will be investigated as this information has important implications for designing therapeutic interventions. Aim 3. To determine the relative effects of PVL, -hemolysin (HLA), and -type phenol-soluble modulins (PSM-) on acute lung injury and necrotizing pneumonia in the rabbit model. These experiments will determine whether other exotoxins similar in their activities to PVL contribute to virulence in the pneumonia model. Aim 4. To determine whether passive and active immunization protects against PVL-induced lung injury and death in the rabbit pneumonia model. Our proposed experiments will increase knowledge of the role of PVL and related toxins in pathogenesis of lung injury and establish a basis for the development of new therapeutic approaches.

描述(申请人提供)：社区相关耐甲氧西林金黄色葡萄球菌(CA-MRSA)，特别是大流行的USA300克隆，与严重感染和高死亡率有关，特别是在肺炎患者中。USA300产生潘顿-瓦伦丁杀白素(PVL)，这是一种有效的外毒素，可以裂解多形核白细胞(PMN)。通常认为PVL是USA300超强毒力的原因，并在坏死性肺炎的发病机制中起关键作用，但来自啮齿动物感染模型的数据存在冲突。啮齿动物中性粒细胞比人中性粒细胞对PVL细胞毒性更不敏感，这可能是不确定的结果的原因。兔和人的中性粒细胞对PVL的易感性相似。假设中性粒细胞在组织破坏过程中发挥作用(因此，靶细胞对PVL效应的易感性很重要)，我们建立了一种兔肺炎模型。在这个模型中，与PVL阳性的亲本相比，同基因PVL阴性的USA300突变体引起致死性肺炎的能力减弱；在PVL互补的突变体中，毒力完全恢复。PVL阳性菌株的感染与人类疾病非常相似。单纯空隙滴注纯化PVL可引起急性肺损伤和肺部炎症的快速发作。本项目的总体目标是确定PVL引起的急性肺损伤、肺部炎症和致死性坏死性肺炎的机制。提出了四个具体目标。目的1.探讨宿主炎症反应在PVL诱导的坏死性肺炎中的作用。我们推测PVL所致的急性肺损伤是由PMN介导的。为了验证这一假设，我们将确定阻断白介素8是否减轻PVL诱导的急性肺损伤和肺部炎症。白介素8是将中性粒细胞招募到肺内的主要趋化因子。目的2.探讨PVL及其相关的双组分毒素--杀白素(LukED)和溶血素(HlgABC)是否单独或协同诱导急性肺损伤和肺部炎症。我们将研究LukED和hlgABC基因的缺失是否会减弱毒力；基因互补是否会恢复毒力；并确定在感染过程中LukED和HlgABC的表达水平。PVL、LukED和HlgABC在诱导急性肺损伤和肺部炎症方面的潜在协同作用也将被调查，因为这些信息对设计治疗干预措施具有重要意义。目的3.探讨PVL、-溶血素(HLA)、-型苯酚-可溶性调理素(PSM-)在兔急性肺损伤和坏死性肺炎模型中的作用。这些实验将确定其他与PVL活性相似的外毒素是否有助于肺炎模型的毒力。目的4.探讨被动免疫和主动免疫对兔肺炎模型肺损伤和死亡的保护作用。我们提出的实验将增加对PVL和相关毒素在肺损伤发病机制中作用的认识，并为开发新的治疗方法奠定基础。