Project 4: Role of Antecedent Influenza Infection in Severity and Outcome of Hemorrhagic MRSA Pneumonia

项目4 -摘要 背景：社区获得性耐甲氧西林菌引起的继发性细菌性肺炎 金黄色葡萄球菌（CA-MRSA）是甲型流感病毒（IAV）感染后患者死亡的主要原因 感染IAV如何诱发严重的CA-MRSA肺炎尚不完全清楚。假设：我们 假设甲型流感病毒神经氨酸酶（iNA）和沙门氏菌之间存在致死协同作用。金黄色α- 溶血素（AH），导致这种感染广泛肺破坏特征， 负责这种协同作用的机制可以减轻严重程度并改善术后患者的预后， 流感出血坏死性CA-MRSA肺炎。具体目标1：确定分子量 iNA增强AH诱导的肺泡-毛细血管屏障破坏的机制。为此， 培养的肺上皮细胞中的ADAM 10蛋白酶活性将与上皮细胞屏障相关 在存在和不存在iNA处理的情况下的结构和功能。具体目标2：阐明 iNA对肺微血管内皮细胞激活AH诱导的血小板-中性粒细胞增加的作用 聚集体（PNA）沉积。在许多软组织感染中，PNA会导致组织破坏。我们有 证明AH是唯一的S。金黄色葡萄球菌外毒素介导人全血中PNA的形成。到 为了确定iNA是否增强了这一过程，我们将测量全血中AH诱导的PNA形成， 在有和没有肺微血管内皮细胞的静态与流动条件下， iNA治疗。具体目标3。为了评估iNA抑制剂在降低死亡率方面的体内功效， 与实验性流感后CA-MRSA肺炎相关。与目前的指导方针相反，我们 已经显示了早期抗病毒治疗的价值，单独给予，在改善实验后的结果， 流感MRSA肺炎，而单独给予典型的抗MRSA抗生素无效。使用 在这个模型中，我们将研究早期和晚期奥司他韦治疗的疗效的机制。 (an iNA抑制剂）单独或与抗生素一起在减少肺破坏和改善 流感后MRSA肺炎对人类健康的影响：这些研究的结果可能表明 目前治疗流感后MRSA肺炎的方法的范式转变。贡献 多学科传染病研究计划：Parimon博士将临床专业知识融合在 肺医学与基础科学的发病机制的认识，严重 细菌性肺炎本提案中所述的研究将增加核心的致病病毒学专业知识 特别是当它与流感后MRSA肺炎有关时。因为其他细菌性软组织感染 据称，先前的病毒感染使病情恶化，这项研究的结果可能广泛适用于 几种威胁生命的疾病。

Project 4 - SUMMARY Background: Secondary bacterial pneumonia caused by community-acquired methicillin resistant Staphylococcus aureus (CA-MRSA) is the leading cause of death in patients following influenza A virus (IAV) infection. How IAV predisposes to severe CA-MRSA pneumonia is not fully understood. Hypothesis: We hypothesize that that a lethal synergism exists between influenza A neuraminidase (iNA) and S. aureus alpha- hemolysin (AH) that contributes to widespread lung destruction characteristic of this infection and that targeting the mechanism responsible for this synergy could lessen severity and improve outcomes in patients with post- influenza hemorrhagic necrotizing CA-MRSA pneumonia. Specific Aim 1: To determine the molecular mechanism whereby iNA augments AH-induced alveolo-capillary barrier destruction. For this, AH-induced ADAM10 protease activity in cultured pulmonary epithelial cells will be correlated with epithelial cell barrier structure and function in the presence and absence of iNA treatment. Specific Aim 2: To elucidate the role of iNA in priming the pulmonary microvascular endothelium for increased AH-induced platelet-neutrophil aggregate (PNA) deposition. PNAs contribute to tissue destruction in many soft tissue infections. We have shown that AH is the sole S. aureus exotoxin that mediates formation of PNA in human whole blood. To determine whether iNA augments this process, we will measure AH-induced PNA formation in whole blood and in the presence of pulmonary microvascular endothelial cells under static vs flow conditions with and without iNA treatment. Specific Aim 3. To assess the in vivo efficacy of an iNA inhibitor in decreasing the mortality associated with experimental post-influenza CA-MRSA pneumonia. Contrary to the current guidelines, we have shown the value of early anti-viral therapy, given alone, in improving outcome of experimental post- influenza MRSA pneumonia, whereas typical anti-MRSA antibiotics given alone were not efficacious. Using this model, we will investigate the mechanisms that underlay the efficacy of early vs late oseltamivir treatment (an iNA inhibitor), alone and together with antibiotics, in reducing lung destruction and improving outcome in post-influenza MRSA pneumonia. Impact on Human Health: Together, results from these studies may signal a paradigm shift in the current approach to treatment of post-influenza MRSA pneumonia. Contribution to Multi-disciplinary Infectious Diseases Research Program: Dr. Parimon blends clinical expertise in pulmonary medicine with a basic science understanding of the mechanisms of pathogenesis of severe bacterial pneumonia. Studies described in this proposal will increase the core's expertise pathogenic virology especially as it relates to post-influenza MRSA pneumonia. Because other bacterial soft tissue infections are purportedly made worse by antecedent viral infection, results from this study could be broadly applicable to several life-threatening diseases.