Mapping the unique features of fetal and neonatal hematopoietic stem and progenitor cells conferring susceptibility to inflammation and infection

项目摘要 新生儿败血症是一个重大的全球健康负担，每年有140万新生儿死亡， 更多的是由于炎症和感染而导致的终身健康问题。新生儿是 特别容易感染脓毒症，部分原因是免疫反应未能充分控制入侵 病原体特别是，新生儿对感染反应的显著中性粒细胞减少症是新生儿感染的主要特征。 导致新生儿死亡的因素，很少发生在成年人身上。成体造血干细胞（HSC）位于 位于造血系统的顶端，产生血液系统的所有谱系，包括中性粒细胞，以及 对炎症信号作出反应，根据需要再生血液系统。实现这一点 通过动态产生具有不同基线的不同多能祖细胞（MPP）亚群， 倾向于某些血统的血细胞，但相当大的可塑性，使他们的相对频率 并且谱系潜力被炎症信号改变。胎儿和新生儿HSC是否会引起类似的 MPP亚群，以及这些围产期MPP亚群是否对炎症反应，以重建血液系统， 与成年人一样的方式尚不清楚。这是一个根本的差距，在我们的理解围产期 造血系统的严重损害我们诊断和治疗新生儿败血症的能力。这项建议 这是一个为期四年的职业发展计划，旨在通过两个重要途径填补这一空白。第一，研究 本申请中提出的策略将建立围产期HSC/MPP生物学的全面路线图 使用小鼠模型作为模板，用于将来分析人HSC/MPP群体以进行转化研究。 在具体目标1中，我们将通过体外试验和体外试验评估胎儿和新生儿HSC/MPP功能。 评估其谱系贡献和再生潜力的体内移植方法及其用途 无偏RNA-seq转录组学分析，以研究调节其功能的分子机制 在不受干扰的发展。在具体目标2中，我们将确定围产期HSC/MPPs的能力， 通过解剖个体对炎症和感染的反应， 关键炎症细胞因子，如IL-1、IL-6、IFNa和TNFa，并采用LPS和Group的体内模型 B链球菌（GBS）绒毛膜炎和早发性脓毒症。二、职业发展与培训 本提案中概述的活动将使PI Amélie柯林斯博士终身独立研究 研究围产期造血的独特特性如何导致新生儿发病率， mortality.柯林斯博士是哥伦比亚大学欧文的儿科医生和助理教授 在免疫学和人类新生儿疾病方面具有重要背景的医学中心。她将补充 该专业知识与培训的发展造血和干细胞生物学的指导下，博士。 Emmanuelle Passegué.完成K 08后，柯林斯博士将准备好承担她自己的监督工作 研究计划旨在通过对围产期造血的新见解来促进新生儿健康。

PROJECT SUMMARY Neonatal sepsis is a significant global health burden, with 1.4 million newborns dying annually and many more with substantial lifelong health problems as a consequence of inflammation and infection. Neonates are uniquely susceptible to sepsis in part due to an immune response that fails to adequately control invading pathogens. In particular, the marked neutropenia characteristic of the neonatal response to infection is a primary contributor to mortality in newborns that rarely occurs in adults. Adult hematopoietic stem cells (HSCs) sit at the top of the hematopoietic hierarchy, giving rise to all lineages of the blood system including neutrophils, and responding to inflammatory signals to regenerate the blood system according to demand. This is achieved through the dynamic production of different multipotent progenitor (MPP) subsets with distinct baseline predispositions toward certain lineages of blood cells but substantial plasticity such that their relative frequency and lineage potentiality is modified by inflammatory signals. Whether fetal and neonatal HSCs give rise to similar MPP subsets, and whether these perinatal MPP subsets respond to inflammation to rebuild the blood system in the same way as adult populations is not known. This is a fundamental gap in our understanding of perinatal hematopoiesis that significantly impairs our ability to diagnose and treat neonatal sepsis. This proposal represents a four year career development plan aimed at filling that gap in two important ways. First, the research strategy proposed in this application will establish a comprehensive roadmap of perinatal HSC/MPP biology using mouse models as a template for future analyses of human HSC/MPP populations for translational studies. In Specific Aim 1, we will evaluate HSC/MPP function in the fetus and neonate through in vitro assays and in vivo transplantation approaches to assess their lineage contributions and regenerative potential, and use unbiased RNA-seq transcriptomic profiling to investigate the molecular mechanisms regulating their function during unperturbed development. In Specific Aim 2, we will determine the ability of perinatal HSC/MPPs to mount an emergency myelopoietic response to inflammation and infection by dissecting individual responses to key inflammatory cytokines such as IL-1, IL-6, IFNa, and TNFa and employing in vivo models of LPS and Group B Streptococcus (GBS) chorioamnionitis and early onset sepsis. Second, the career development and training activities outlined in this proposal will position the PI, Dr. Amélie Collins, for a life-long independent research career investigating how the unique properties of perinatal hematopoiesis contribute to neonatal morbidities and mortality. Dr. Collins is a neonatologist and Assistant Professor of Pediatrics at Columbia University Irving Medical Center with significant background in immunology and human neonatal conditions. She will complement that expertise with training in developmental hematopoiesis and stem cell biology under the mentorship of Dr. Emmanuelle Passegué. Upon completion of this K08, Dr. Collins will be ready to assume oversight of her own research program aimed at advancing neonatal health through new insights into perinatal hematopoiesis.