The Role of Eicosanoid-PPAR axis in Exacerbating Post-Influenza Staphylococcus aureus Super-infection

项目总结/摘要 流感后的继发性细菌感染（双重感染）可导致细胞因子风暴（一种过度分泌物 免疫反应），其经常导致患者的肺炎和死亡。我们的工作集中在分子 免疫系统在微生物感染后恢复体内平衡的机制。采取一种整体的、 系统的方法，我们研究了炎症反应在单一（流感或葡萄球菌 金黄色葡萄球菌）和重叠感染（流感/S. aureus)具有良好的抗菌活性。我们在人乳腺癌组织中进行了转录和脂质组学分析。 来自小鼠重复感染模型的样品。我们的脂质组学分析集中在类花生酸上，因为它们 在诱导和消除炎症中起关键作用。与单一感染相比，我们发现 在重复感染期间类花生酸亚群的过量产生。这些脂质（抗炎CYP 450脂质 介体，主要是DHET）可以激活核受体和转录因子PPAR α和PPAR γ。 在流感单次感染期间，缓解期CYP脂质（主要是EET）中度诱导 允许适当的抗炎反应以促进恢复体内平衡。我们假设 虽然EET可促进微生物感染后炎症的生理消退，但DHET在 在重复感染期间的异常水平导致巨噬细胞极化的改变和 细菌清除。控制细菌病原体的失败放大了免疫信号，以招募额外的 最终导致不可逆的组织损伤。我们将采取以下措施 以研究类花生酸-PPAR轴对炎症反应的影响。 首先，我们将确定干扰类花生酸-PPAR轴对分离或扩增PPAR γ的影响。 单次和重复感染期间的炎症。我们将使用化学抑制剂和基因 模型，以确定动物在单次和超 感染我们将确定脂质组学特征，以评估抑制剂对脂质代谢的特异性影响。 类花生酸代谢网络。我们还将确定细菌/病毒载量、细胞结构、病理组织学和 巨噬细胞的靶向转录谱。第二，我们将确定 类花生酸激活的PPARα/γ对免疫信号、巨噬细胞极化和免疫代谢的调节作用 体外巨噬细胞极化（经典或替代激活）可放大或缓解炎症 应答我们将测定不同CYP 450代谢产物在小鼠体内激活PPARα/γ的效价 和原代人巨噬细胞。我们将确定类花生酸（CYP 450代谢产物）如何影响免疫 信号传导、巨噬细胞极化和脂质代谢。有趣的是，虽然炎症的诱导 作为积极研究的主题，炎症消退的机制已经 难以捉摸。通过深入了解单一感染和双重感染时炎症消退情况，我们将开发 用于感染和免疫相关人类疾病的新的治疗靶点。

PROJECT SUMMARY/ABSTRACT Secondary bacterial infection following influenza (super-infection) can lead to cytokine storm (an overexuberant immune response) that often leads to pneumonia and death in patients. Our work focuses on the molecular mechanisms by which the immune system returns to homeostasis after microbial infections. Taking a holistic, systems approach, we investigated the inflammatory responses during a single (influenza or Staphylococcus aureus) and super-infection (influenza/S. aureus). We conducted transcriptional and lipidomic analyses in samples from a mouse super-infection model. Our lipidomic analysis was focused on eicosanoids because they play critical roles in inducing and resolving inflammation. When compared to single infections, we discovered an overproduction of a subset of eicosanoids during super-infection. These lipids (anti-inflammatory CYP450 lipid mediators, primarily DHET) can activate the nuclear receptors and transcription factors PPARa and PPARg. During influenza single infection, moderate induction of CYP lipids (primarily EET) during the resolution phase allows for appropriate anti-inflammatory responses to promote the return to homeostasis. We hypothesize that while EET promotes the physiological resolution of inflammation after microbial infections, DHET produced at an aberrant level during super-infection leads to the alteration in macrophage polarization and inhibition of bacterial clearance. The failure to control the bacterial pathogen amplifies the immune signals to recruit additional immune cells which eventually cause irreversible tissue damage. We will take the following approaches during single and super-infection to investigate the effects of the eicosanoid-PPAR axis on the inflammatory response. First, we will determine the effects of perturbing the eicosanoid-PPAR axis on the resolution or amplification of inflammation during single and super-infection. We will use chemical inhibitors in combination with genetic models to determine whether the animals will be protected from or succumb to disease during single and super- infection. We will determine the lipidomic profiles to assess the specific effects of the inhibitors have on the eicosanoid metabolism networks. We will also determine the bacterial/viral loads, cellularity, pathohistology, and targeted transcriptional profiling of macrophages. Second, we will determine the mechanism by which eicosanoid-activated PPARα/γ modulates immune signaling, macrophage polarization and immune metabolism in vitro. Macrophage polarization (classically or alternative activated) can amplify or resolve inflammatory responses. We will determine the potency of different CYP450 metabolites to activate PPARα/γ within mouse and primary human macrophages. We will determine how eicosanoids (CYP450 metabolites) affect the immune signaling, macrophage polarization, and lipid metabolism. Interestingly, While the induction of inflammation has been the subject of active investigation, the mechanisms underlying the resolution of inflammation have been elusive. By gaining insights into the resolution of inflammation during single and super-infection, we will develop novel therapeutic targets for infection- and immune-related human diseases.