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

项目摘要 微生物感染是全世界婴儿死亡的主要原因。对于特别脆弱的人群 如早产儿和低出生体重儿，侵入性感染的风险进一步上升。新生儿 这一时期是由一个独特的，通常被描述为不成熟的免疫系统定义的。保护性的许多功能 与年龄较大儿童和成人相比，宿主对感染的反应不足。本实验室 鉴定了免疫抑制细胞因子白细胞介素（IL）-27的表达在人体中升高， 小鼠新生儿。其他最近的研究表明IL-27是早发性新生儿败血症的生物标志物。 这表明升高的IL-27可能是一个危险因素，当在细菌感染期间进一步升高时， 挑战，破坏宿主的免疫反应目前提案的总体前提是IL-27是 宿主分子，其代表免疫干预的靶标，以改善宿主应答并减少 在生命早期易受细菌感染。我们在小鼠模型中提出了强有力的证据， IL-27信号传导的增加转化为存活率的增加、体重增加的改善和细菌清除的增强。 在新生儿败血症期间。为了进一步了解IL-27如何调节免疫反应， 新生儿败血症，我们需要确定负责IL-27产生的细胞类型的完整库， 了解这些人群在感染过程中可能如何变化，并进一步定义他们的 功能.我们将使用IL-27报告小鼠来解决这一理解上的差距， 在IL-27 p28启动子的控制下的荧光蛋白。使用报告小鼠的整体动物成像 再加上发光细菌，这将使我们能够识别IL-27生产者， 分析，并将它们在感染组织中的存在与细菌负荷相关联。我们还试图了解 IL-27介导的抑制活性所需的细胞信号传导途径，以及对 细菌负荷我们假设信号转导子和转录激活子（Stat）-3信号 在IL-27受体结合的下游干扰溶酶体运输和酸化。最终结果是 降低细菌清除率。最后，一个主要目的是研究拮抗IL-10的结果。 27在新生儿败血症期间，目的是建立一种免疫方法， 目前我们只能提供抗生素和支持性治疗。抗生素耐药性混淆 我们对这种方法的依赖。施用与荧光标记缀合的中和抗体将 允许在真实的时间内观察组织渗透 控制细菌生长。在该项目完成时，我们预计已进行临床前研究。 验证一种有前途的免疫学方法，以改善免疫应答和易感性 新生儿感染疾病，以及提供了一个增强的了解IL-27如何调节宿主 新生儿败血症期间的免疫和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.