Understanding IL-27 as a negative regulator of protective immunity during neonatal sepsis

项目总结 微生物感染是全球婴儿死亡的主要原因。针对特别易受伤害的人群 例如早产儿和低出生体重儿，侵袭性感染的风险进一步升级。新生儿 这一时期的定义是一种独特的、通常被描述为不成熟的免疫系统。保护性产品的许多功能 与年龄较大的儿童和成年人相比，宿主对感染的反应是不足的。我们的实验室有 发现免疫抑制细胞因子白介素27在人类和 小鼠的新生儿。最近的其他研究表明，IL-27是早发性新生儿败血症的生物标志物。 这表明IL-27的升高可能是一个危险因素，当在细菌感染期间进一步增加时 挑战，损害宿主的免疫反应。目前提案的总体前提是，IL-27是 一种宿主分子，代表免疫干预的目标，以改善宿主的反应并减少 在生命早期对细菌感染的敏感性。我们在一个小鼠模型中提出了强有力的证据，证明 IL-27信号转译为增加存活率、改善体重增加和增强细菌清除 在新生儿败血症期间。为了增进我们对IL-27如何调节免疫反应的了解 新生儿败血症，我们需要确定产生IL-27的完整细胞类型， 了解这些人群在感染过程中可能发生的变化，并进一步定义其 功能性。我们将使用IL-27报告小鼠来解决这一理解上的差距，该小鼠表达 IL-27p28启动子调控的荧光蛋白。使用报告鼠的全动物成像 再加上发光细菌，这将使我们能够识别IL-27的产生者，对它们进行分类，以便进一步发挥作用 分析，并将它们在受感染组织中的存在与细菌负荷相关联。我们还试图理解 IL-27介导的抑制活性所需的细胞信号通路和对 细菌负担。我们假设信号转导和转录激活因子(Stat)-3信号 IL-27受体下游结合干扰溶酶体转运和酸化。最终结果是 细菌清除受损。最后，一个主要目标是研究拮抗IL-2的结果。 27新生儿败血症期间，目的是建立一种针对感染性疾病的免疫治疗方法 我们目前只能为这些疾病提供抗生素和支持性护理。抗生素耐药性令人困惑 我们对这种方法的依赖。给药连接到荧光标记的中和抗体将 允许实时可视化组织渗透并直接关联拮抗剂的存在 控制细菌的生长。在这个项目完成时，我们预计已经进行了临床前 一种有前景的免疫治疗方法的有效性验证，以改善免疫应答和敏感性 对新生儿感染疾病的预防，以及对IL-27如何调节宿主的进一步了解 新生儿败血症时的免疫及与细菌病原体的相互作用。

PROJECT SUMMARY Microbial infections are a major cause of infant mortality worldwide. For particularly vulnerable populations such as pre-term and low birthweight babies, the risk of invasive infections further escalates. The neonatal period is defined by a distinct, often described as immature, immune system. Many features of a protective host response to infection are deficient as compared with older children and adults. Our laboratory has identified that expression of the immune suppressive cytokine interleukin (IL)-27 is elevated in human and murine neonates. Other recent studies have shown IL-27 to be a biomarker for early onset neonatal sepsis. This suggests that elevated IL-27 may represent a risk factor and when further increased during bacterial challenge, compromise the host immune response. The overall premise of the current proposal is that IL-27 is a host molecule that represents a target for immune intervention to improve the host response and reduce susceptibility to bacterial infection early in life. We present strong evidence in a mouse model that the absence of IL-27 signaling translates to increased survival, improved weight gain, and enhanced clearance of bacteria during neonatal sepsis. To advance our knowledge of how IL-27 regulates the immune response during neonatal sepsis, we need to identify the complete repertoire of cell types responsible for IL-27 production, understand how these population may change over the course of infection, and further define their functionality. We will address this gap in understanding using an IL-27 reporter mouse that expresses a fluorescent protein under control of the IL-27p28 promoter. Using whole-animal imaging of the reporter mouse coupled with luminescent bacteria, this will allow us to identify IL-27 producers, sort them for further functional analysis, and correlate their presence in infected tissues with the bacterial burden. We also seek to understand cellular signaling pathways required for IL-27-mediated suppressive activity and compromised control of the bacterial burden. We hypothesize that signal transducer and activator of transcription (Stat)-3 signals downstream of IL-27 receptor binding to interfere with lysosomal trafficking and acidification. The net result is compromised bacterial clearance. Lastly, a primary objective is to investigate the outcomes of antagonizing IL- 27 during neonatal sepsis with the aim of establishing an immunotherapeutic approach for an infectious disease for which we can currently only offer antibiotics and supportive care. Antibiotic resistance confounds our reliance on this approach. Administration of a neutralizing antibody conjugated to a fluorescent tag will allow for visualization of tissue penetration in real time and directly correlate the presence of the antagonist with control of bacterial growth. At the completion of this project, we expect to have performed preclinical validation of a promising immunotherapeutic approach to improve immunological responses and susceptibility to infection disease in newborns, as well as provided an enhanced understanding of how IL-27 regulates host immunity and interactions with bacterial pathogens during neonatal sepsis.