Immunomodulation by splenic megakaryocytes and platelets in sepsis

项目摘要 败血症是宿主对感染的一种失调反应，最终导致器官衰竭，导致数百万人死亡。 全世界每年都会出现这种情况，而且随着人口老龄化，发病率也在增加。从根本上说，缺乏 对脓毒症复杂宿主免疫反应的认识限制了靶向免疫反应的发展 除了抗生素和支持性护理措施外，没有其他治疗方法。在其核心，有 脓毒症的实质免疫病理学与过度活跃的免疫反应和 病原体清除无效。我们和其他人研究了血小板在免疫反应中的关键作用 在急性感染期间，包括肺在髓外血小板生物生成中的作用。在此应用程序中， 我们将探讨作为中枢免疫器官的脾在髓外巨核细胞生成和血小板生成中的作用 脓毒症的生产。根据初步数据，我们假设脾在 脓毒症时的血小板生物生成以及从脾产生的血小板具有免疫调节作用和 在宿主防御中很重要。在目标1中，我们将利用腹膜炎和多菌败血症的小鼠模型。 了解在这种情况下“应激”血小板生物生成的机制。我们会研究 依赖肾上腺素能的造血祖细胞动员在脓毒症和脓毒症中的作用 规范这一过程的利基促进因素。在目标2中，我们将询问循环的嫁接 脾中的造血祖细胞，它们成熟为巨核细胞，以及介体(SCF， CXCL12、IL-3)调节这一过程。使用最先进的技术，如活体成像和血统 通过脾移植实现追踪，我们将检验脾对 脓毒症时的血小板生物生成。在目标3中，我们将使用新的血小板单细胞rna测序方法。 测试小鼠和人类体内稳态和败血症期间的血小板异质性。在这个目标下，我们将 通过将免疫倾斜的血小板输入脓毒症小鼠来测试一种治疗脓毒症的新的细胞疗法，并测试 治疗效果。总而言之，这些研究将产生关于 脾在髓外巨核细胞和血小板生成中的作用及血小板驱动的重要性 免疫，这将是设计新的治疗方法来治疗败血症的基础。

Project Summary Sepsis is a dysregulated host response to infection that culminates in organ failure leading to millions of deaths worldwide each year with an increasing incidence as the population ages. There is a fundamental lack of understanding of the complex host immune response in sepsis that has limited the development of targeted therapeutics for which there are none beyond antibiotics and supportive care measures. At its core, there is substantial immunopathology in sepsis with contributions from an overly exuberant immune response and ineffective pathogen clearance. We and others have studied the critical role of platelets in immune responses during acute infections, including the role of the lung in extramedullary platelet biogenesis. In this application, we will explore the role of the spleen, a central immune organ, in extramedullary megakaryopoiesis and platelet production in sepsis. Based on preliminary data, we hypothesize that the spleen co-opts a significant role in platelet biogenesis during sepsis and that the platelets produced from the spleen are immunomodulatory and important in host defense. In Aim 1, we will utilize a mouse model of peritonitis and polymicrobial sepsis resulting in thrombocytopenia to understand the mechanics of ‘stressed’ platelet biogenesis in this setting. We will study the role of adrenergic-dependent hematopoietic progenitor mobilization from the bone marrow during sepsis and the niche-promoting factors that regulate this process. In Aim 2, we will interrogate the engraftment of circulating hematopoietic progenitors in the spleen, their maturation into megakaryocytes, and the mediators (SCF, CXCL12, IL-3) regulating this process. Using state-of-the-art techniques such as intravital imaging and lineage tracing enabled by splenic transplantation, we will test the hypothesis that the spleen significantly contributes to platelet biogenesis during sepsis. In Aim 3, we will use novel methods of single-cell RNA sequencing of platelets to test for platelet heterogeneity during homeostasis and sepsis in mice and humans. Within this aim, we will test a novel cellular therapy for sepsis by transfusing immune-skewed platelets into septic mice and testing for therapeutic benefit. In summary, these studies will produce paradigm-shifting knowledge on the role of the spleen in extramedullary megakaryopoiesis and platelet production and the importance of platelet driven immunity, which will be foundational in the design of new therapeutic approaches to treat sepsis.