PCSK9 and Pediatric Sepsis-Related MODS

摘要 这项R21探索性拨款是为响应资助机会而重新提交的申请 公告编号PAR-16-195，“研究以促进对 儿童多器官功能障碍综合征“。感染性休克是一种常见的儿科疾病。 重症监护病房是导致多器官功能障碍综合征(MODS)的最常见原因之一。它 因此，更好地了解儿科特有的感染性休克生物学将导致更好地理解 儿科多器官功能障碍。枯草杆菌前蛋白转换酶/可可素9(PCSK9)在清除 低密度脂蛋白(LDL)。由于低密度脂蛋白代谢与细菌脂类部分的清除密切相关， 最近的研究探索了PCSK9在脓毒症中的作用。在患有败血症的成年人中，PCSK9功能丧失 突变与提高存活率有关。这一临床观察在实验中得到证实。 脓毒症，其中PCSK9的基因消融或药物抑制对成年小鼠具有保护作用 多菌败血症的挑战。这增加了利用PCSK9抑制作为一种 脓毒症的新治疗策略。FDA批准的PCSK9抑制剂的可用性进一步提高 对这种方法感兴趣。我们对400多名感染性休克儿童进行了基因分型，发现情况正好相反。 结果。在感染性休克的儿童中，PCSK9功能缺失突变与 即使在根据疾病严重程度和年龄进行调整后，不良结局的风险也会增加。对这次重新提交来说是新的， 我们现在报告PCSK9基因缺失的幼年小鼠在多菌败血症后的死亡率更高，与 到野生型小鼠。我们现在还表明，未成熟肝脏的炎症反应非常明显。 与成人肝脏不同。这些结果支持了我们长期以来的观点，即新的脓毒症 基于成人和成人实验模型的研究开发的治疗方法可能不是生物学上的 适合儿童，反映了发育对宿主对脓毒症反应的强烈影响。这些 结果还提供了进行儿科宿主独有的机械性研究的机会 直接考虑发育对宿主对败血症反应的影响，因此， 儿科多器官功能障碍。这是我们提案的重点。使用一个幼年模型，在这个模型中，我们诱导多菌体 在14日龄小鼠的脓毒症中，我们提出了两个具体的目标。在具体目标1中，我们将检验假设 抑制PCSK9在幼年多菌败血症模型中是有害的。这一目标将利用 PCSK9缺失小鼠和中和抗PCSK9抗体。在具体目标2中，我们将检验假设 PCSK9增加了多菌败血症幼年模型的肝脏炎症。这一目标将利用 低密度脂蛋白受体缺失小鼠和氯化钆介导的枯否细胞耗竭。总的来说，这些研究 本文的提出将阐明PCSK9在儿童败血症中的作用，并阐明败血症的新机制 儿科宿主特有的生物学。

ABSTRACT This R21 exploratory grant is a resubmission application in response to the funding opportunity announcement number PAR-16-195, “Research to Advance the Understanding and Management of the Multiple Organ Dysfunction Syndrome in Children”. Septic shock is a prevalent condition in the pediatric intensive care unit and one of the most common causes of multiple organ dysfunction syndrome (MODS). It follows that a better understanding of pediatric-specific septic shock biology will lead to a better understanding of pediatric MODS. Proprotein convertase subtilisin/kexin type 9 (PCSK9) plays a major role in clearance of low-density lipoprotein (LDL). Since LDL metabolism is closely linked to clearance of bacterial lipid moieties, recent studies have explored the role of PCSK9 in sepsis. In adults with sepsis, a PCSK9 loss of function mutation is associated with improved survival. This clinical observation was corroborated in experimental sepsis, wherein genetic ablation or pharmacologic inhibition of PCSK9 confers protection in adult mice challenged with polymicrobial sepsis. This raises the intriguing possibility of leveraging PCSK9 inhibition as a novel therapeutic strategy for sepsis. The availability of an FDA approved PCSK9 inhibitor further raises interest in this approach. We genotyped over 400 children with septic shock and found the opposite result. Among children with septic shock, a PCSK9 loss of function mutation is independently associated with increased risk of poor outcome, even after adjusting for illness severity and age. New to this resubmission, we now report that juvenile PCSK9 null mice have a higher mortality rate after polymicrobial sepsis, compared to wild type mice. We also now show that the inflammatory response of the immature liver is dramatically different than that of the adult liver. These results support our long-standing contention that novel sepsis therapies developed based on studies in adults and adult experimental models, might not be biologically appropriate for children, reflecting the strong influence of development on the host response to sepsis. These results also provide an opportunity to conduct mechanistic studies that are unique to the pediatric host and directly consider the influence of development on the host response to sepsis, and hence, the biology of pediatric MODS. This is the focus of our proposal. Using a juvenile model, in which we induce polymicrobial sepsis in 14-day-old mouse pups, we propose two Specific Aims. In Specific Aim 1, we will test the hypothesis that inhibition of PCSK9 is deleterious in a juvenile model of polymicrobial sepsis. This Aim will make use of PCSK9 null mice and a neutralizing anti-PCSK9 antibody. In Specific Aim 2, we will test the hypothesis that PCSK9 augments hepatic inflammation in a juvenile model of polymicrobial sepsis. This Aim will make use of LDL receptor null mice and gadolinium chloride-mediated Kupffer cell depletion. Collectively, the studies propose here will clarify the role of PCSK9 in pediatric sepsis and elucidate a novel mechanism of sepsis biology specific to the pediatric host.