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 假设甲型流感神经氨酸酶(INA)和金黄色葡萄球菌之间存在致命的协同作用。 导致广泛肺破坏的溶血素(AH)是这种感染的特征和靶向 这种协同作用的机制可以减轻严重程度并改善患者的预后。 流感出血性坏死性CA-MRSA肺炎。具体目标1：确定分子 INA增强AH诱导的肺泡-毛细血管屏障破坏的机制。为此，由AH诱导 培养的肺上皮细胞ADAM10蛋白酶活性与上皮细胞屏障相关 有无异丙肾上腺素处理的结构和功能。具体目标2：阐明 INA激活肺微血管内皮细胞对抗AH诱导的血小板-中性粒细胞增多 骨料(PNA)沉积。在许多软组织感染中，PNA有助于组织破坏。我们有 结果表明，AH是唯一一种介导人全血中PNA形成的金黄色葡萄球菌外毒素。至 确定异丙肾上腺素是否增强这一过程，我们将测量AH诱导的全血PNA的形成和 静态和流动条件下肺微血管内皮细胞的存在 INA治疗。具体目的3.评估INA抑制剂在降低死亡率方面的体内效果 与实验性流感后CA-MRSA肺炎有关。与目前的指导方针相反，我们 已经显示出单独给予早期抗病毒治疗在改善实验后的结果方面的价值。 流感耐甲氧西林金黄色葡萄球菌肺炎，而单独使用典型的抗耐甲氧西林金黄色葡萄球菌抗生素并不有效。vbl.使用 在这个模型中，我们将研究早期和晚期奥司他韦治疗效果的机制。 (一种INA抑制剂)单独和与抗生素一起使用，在减少肺破坏和改善预后方面 流感后耐甲氧西林金黄色葡萄球菌肺炎。对人类健康的影响：这些研究的结果加在一起可能表明 目前治疗流感后耐甲氧西林金黄色葡萄球菌肺炎方法的范式转变。对以下项目的贡献 多学科传染病研究计划：Parimon博士在 肺脏医学对重症肺炎发病机制的基础科学认识 细菌性肺炎。这项建议中描述的研究将增加核心致病病毒学的专业知识 尤其是在涉及流感后MRSA肺炎的情况下。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 几种危及生命的疾病。

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.