Anti-inflammatory bioactive lipids exacerbating Staphylococcus aureus infection post influenza

项目总结/摘要 流感后继发性细菌感染（双重感染）是一种严重的临床并发症，通常 导致肺炎和患者死亡。在大多数感染模型中，单一的微生物物种或生物体 病原体用于在宿主中诱导损伤或疾病。然而，人类不断地暴露在 多种微生物病原体。在免疫系统中产生的信号串扰 在很大程度上被忽视了。因此，需要一种不偏不倚的、整体的系统生物学方法来解读 哺乳动物宿主、流感病毒和细菌病原体之间的分子相互作用。我们有 以前使用这种方法来研究免疫应答在单一（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。我们将脂质组学分析集中在类花生酸上，因为它们 是在炎症的诱导和消退中起关键作用的信号分子。在超级 感染，与单一感染相比，抗炎CYP 450代谢物，天然配体 核受体PPAR α以显著更高水平产生。我们假设这些脂质 通常促进炎症的生理消退。然而，在重叠感染期间，CYP 450 代谢物在病理水平上产生，导致先天免疫中PPAR α的过度激活 细胞PPAR α的活化反过来损害了中性粒细胞和单核细胞的抗菌功能。 细菌的持续存在提供了免疫信号，放大了前馈回路，以招募更多的免疫 细胞，从而导致组织损伤和最终死亡。我们将采取以下措施 探讨生物活性脂质-PPAR α轴在先天免疫中的作用 功能和信令。首先，我们将鉴定浸润性中性粒细胞和巨噬细胞转录网络。 单核细胞是在S.金黄色葡萄球菌感染或 没有流感病史。我们将进一步表征中性粒细胞和单核细胞的抗菌功能 在存在遗传（野生型C57/B16对Ppara-/-小鼠）和化学（激动剂和抑制剂）的情况下 对抗PPAR α）扰动。使用shRNA和基因编辑，我们将确定基因间的相互作用因子。 PPAR α，其协同改变转录应答。其次，我们将确定脂质组学 当细菌的持续存在触发了细菌的进一步渗透时， 免疫细胞。我们将研究是否使用化学抑制剂对抗PPAR α和类花生酸 代谢途径可以减轻在重复感染期间增加的发病率和死亡率表型。 应用转录和脂质组学方法研究单次和多次给药后细胞内活性脂质-PPAR α轴的表达。 超感染将提供对超感染期间驱动免疫串扰的机制的重要见解。 并鉴定针对流感的新的宿主定向治疗靶点。

PROJECT SUMMARY/ABSTRACT Secondary bacterial infection following influenza (super-infection) is a serious clinical complication that often leads to pneumonia and death in patients. In most infection models, a single species or organism of microbial pathogen is used to induce an insult or disease in the host. However, humans are constantly exposed to a multitude of microbial pathogens simultaneously. The resulting signaling crosstalk in the immune system has largely been overlooked. An unbiased, holistic systems biology approach, therefore, is required to decipher the molecular interactions between the mammalian host, influenza virus and the bacterial pathogen. We have previously used this approach to study the immune response during 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. We focused our lipidomic analysis on eicosanoids because they are signaling molecules that play critical roles in the induction and resolution of inflammation. During super- infection, when compared to single infections, anti-inflammatory CYP450 metabolites, natural ligands for the nuclear receptor PPARa, were produced at a significantly higher level. We hypothesize that these lipids normally promote the physiological resolution of inflammation. However, during super-infection, CYP450 metabolites are produced at a pathological level leading to an over-activation of PPARa in innate immune cells. The activation of PPARa, in turn, compromises the anti-bacterial function of neutrophils and monocytes. The persistence of bacteria provides immune signals that amplify a feedforward loop to recruit more immune cells, thus contributing to tissue damage and eventual mortality. We will take the following approaches during single and super-infection to investigate the effects of the bioactive lipids-PPARa axis on the innate immune function and signaling. First, we will identify the transcriptional networks of infiltrating neutrophils and monocytes, the predominant cell types recruited to clear bacterial pathogens during S. aureus infection with or without prior influenza. We will further characterize the anti-bacterial function of the neutrophils and monocytes in the presence of genetic (wildtype C57/Bl6 versus Ppara–/– mice) and chemical (agonists and inhibitors against PPARa) perturbations. Using shRNA and gene editing, we will determine the genetic interactors of PPARa which collaborate to alter the transcriptional response. Second, we will determine the lipidomic landscape during the late phase of super-infection when bacterial persistence triggers further infiltration of immune cells. We will investigate whether using chemical inhibitors against PPARa and the eicosanoid metabolic pathways can alleviate the increased morbidity and mortality phenotype during super-infection. Using transcriptional and lipidomic approaches to study the bioactive lipids-PPARa axis during single and super-infection will provide significant insights into the mechanisms driving immune cross-talk during super- infections and identify novel host-directed therapeutic targets for influenza.