The Role of the Inflammasome in Neonatal Sepsis

描述(申请人提供)：新生儿败血症是最困难和最昂贵的问题之一，需要治疗和预防。尽管进行了抗菌治疗，39%患有败血症的新生儿死亡或遭受严重的慢性疾病。新生儿-宿主对败血症的免疫反应及其对不良长期结局的影响的调查一直落后于年龄较大的儿童和成年人。在我的团契训练期间，我开发并验证了一种临床相关的多菌败血症新生小鼠模型，以分析新生儿对败血症诱因的特异性免疫反应。我们发现，与年轻人相比，新生儿的先天免疫反应减弱，更容易发生败血症。具体地说，败血症小鼠新生儿产生的IL-1比成年小鼠少60倍。IL-1的产生对先天免疫细胞功能至关重要，与炎症体功能密切相关。因此，我们建议利用缺乏关键炎症体成分的转基因敲除小鼠来探索炎症体信号在小鼠新生儿败血症中的作用。接下来，我们将确定新生儿和成人在天然免疫受体(TLR)激活后上下游炎症体信号(炎症体特异性mRNA表达和蛋白质产生)方面的差异。最后，我们将确定增强炎症体激活(使用基因敲入人源化小鼠)或其成熟(活性)产物(IL-1β、IL-18)作为新生儿败血症潜在治疗方法的作用。总而言之，我们将寻找个体发育过程中迄今未知的炎性小体发育特征，并通过确定炎性小体信号的作用来产生关于目前鲜为人知的新生儿败血症参数的新知识。因此，确定炎性小体成分的特定缺陷对新生儿败血症和成人败血症的影响，并提供关于它们在新生儿败血症易感性和转归中的潜在重要性的直接证据将是 代表着这一研究前沿的重大进展。此外，这项研究将有助于开发急需的新生儿败血症易感性的生物标志物，并确定新的治疗靶点，例如旨在改善败血症结局的炎症获得功能免疫治疗。我们将确定以下方面的差异 炎症体信号转导导致败血症新生儿和成人IL-1产生的巨大差异。查明这一巨大差异背后的机制(S)将使我们能够制定有针对性的方法，从而可能导致改善结果。因此，我们将探索在最近的一项多中心试验(NEJM 2011)中静脉注射免疫球蛋白治疗新生儿败血症的阴性结果后，炎性小体激活或其成熟产品作为新生儿败血症新型免疫疗法的潜在翻译价值。我们推测，我们对新生儿最具挑战性的问题之一的关注与NIGMS的战略使命是一致的，即为疾病诊断、治疗和预防方面的进步以及培养下一代内科科学家奠定基础。

DESCRIPTION (provided by applicant): Neonatal sepsis is one of the most difficult and costly problems to treat and prevent. Despite antimicrobial therapy, 39% of neonates with sepsis die or suffer major chronic morbidity. Investigations of the neonatal-host immune response to sepsis and its impact on poor long-term outcomes have lagged behind older children and adults. During my fellowship training I developed and validated a clinically-relevant neonatal murine model of polymicrobial sepsis to analyze the neonatal-specific immune response to sepsis-causing agents. We found that neonates exhibit an attenuated innate immune response and are more susceptible to sepsis compared to young adults. Specifically, septic murine neonates produced up to 60 times less IL-1¿ than adults. IL-1¿ production, critical for innate immune cellular function, is intimately linked to inflammasome function. Therefore, we propose to explore the role of inflammasome signaling during murine neonatal sepsis using transgenic knockout mice lacking key inflammasome components. Next, we will determine the differences between neonates and adults in upstream and downstream inflammasome signaling (inflammasome-specific mRNA expression and protein production) following activation of innate immunity receptors (TLRs). Lastly, we will determine the role of enhanced inflammasome activation (using a genetic knock-in humanized mouse) or administration of its mature (active) products (IL-1¿, IL-18) as potential therapies for neonatal sepsis. Cumulatively, we will search for hitherto unknown features of inflammasome development during ontogeny and generate new knowledge about currently poorly understood parameters of the neonatal sepsis through determination of the role of inflammasome signaling. Thus, determining the impact of specific deficiencies in inflammasome components on neonatal vs. adult sepsis and providing direct proof about their potential importance in the susceptibility to and outcome of neonatal sepsis will represent major advance in this research front. Moreover, this investigation will help in the development of much needed biomarkers for neonatal sepsis susceptibility and identification of novel targets for therapy, such as inflammasome gain-offunction immunotherapy directed at improving sepsis outcomes. We will identify the differences in inflammasome signaling intermediates that result in the large discrepancy in IL-1¿ production between septic neonates and adults. Identification of mechanism(s) behind this large difference will allow development of targeted approaches that may lead to improved outcomes. We will thus explore the potential for translational value of inflammasome activation or for provision of its mature products as novel immunotherapies for neonatal sepsis in the aftermath of the negative outcome of intravenous immunoglobulin therapy for neonatal sepsis in a recent multicenter trial (NEJM 2011). We surmise that our focus on one of the most challenging problems in neonatology is consistent with the NIGMS' strategic mission to develop the foundation for advances in disease diagnosis, treatment and prevention as well as development of the next generation of physician-scientists.