MYELOPOIETIC STIMULATION FOLLOWING BURN INJURY

尽管重症监护取得了进展，但由于脓毒症诱导的全身炎症反应综合征（SIRS）和多系统器官衰竭，大面积烧伤患者的死亡率仍然很高。 严重烧伤患者经常表现出不受控制的过度生产的促炎细胞因子和前列腺素类由于持续的单核细胞/巨噬细胞活化。 许多微生物感染和炎性损伤导致单核细胞产生增加，这是由单核细胞谱系特异性集落刺激因子M-CSF的伴随升高驱动的。 然而，很少有人研究热损伤中单核细胞产生的调节。 此外，从未探索过增加数量的单核细胞活化的可用性作为导致严重烧伤中SIRS发展的细胞因子过度产生的潜在原因。 这一假设是严重烧伤和脓毒症导致骨髓环境有利于单核细胞生成增加。 这种持续增加数量的单核细胞/巨噬细胞活化的可用性可能通过失调的细胞因子产生潜在地驱动炎症。 我们将在小鼠背部烧伤模型中测试这一前提，在该模型中，败血症将在初始烧伤后的临床相关早期和晚期时间点诱导。 在第一个目标中，我们将a）通过流式细胞术分析单核细胞生成发育抗原，（ER-MP 12和20）和克隆形成测定; B）测量血浆和骨髓M-CSF水平; c）总骨髓细胞和单核细胞发育的不同区室中M-CSF受体（c-fms）的mRNA和细胞表面表达; d）记录烧伤和脓毒症中不同单核细胞生成区室中单核细胞发育相关转录因子PU.1和Egr-1的表达模式。 在第二个目的中，使用M1细胞的体外单核细胞分化，我们将评估在烧伤中升高的不同细胞因子如IL-1、IL-6和IL-10以及前列腺素类PGE 2如何影响a）单核细胞分化：B）c-fms表达; c）PU. 1和Egr-1活化和d）细胞因子产生和功能。 在第三个目标中，我们将确定取消免疫抑制和骨髓生成调节类前列腺素PGE 2是否可以使我们的小鼠模型中的单核细胞生成、c-fms表达、PU.1和Egr-1表达以及单核细胞释放的动力学正常化。这些研究将直接验证我们的假设，并提供重要信息的地位和机制的单核细胞在烧伤和脓毒症。 更重要的是，这些研究将有助于解释严重烧伤患者中异常细胞因子的产生，并为合理治疗提供目标，以提高他们的生存率。

Despite advances in critical care, mortality among patients with massive burns still remains high due to sepsis-induced systemic inflammatory response syndrome (SIRS) and multisystem organ failure. Patients with severe burns often manifest uncontrolled overproduction of proinflammatory cytokines and prostanoids due to continued monocyte/macrophage activation. Many microbial infections and inflammatory insults result in increased monocyte production driven by a concomitant elevation in monocytic lineage specific colony-stimulating factor, M-CSF. Yet, little research has been done on the regulation of monocyte production in thermal injury. Furthermore, the availability of increasing number of monocytes for activation as an underlying cause for cytokine overproduction leading to the development of SIRS in severe burn injury has never been explored. The hypothesis of this propsal is that severe burn injury and sepsis result in a bone marrow milieu conducive to increased monocytopoiesis. This continued availa-bility of increasing number of monocytes/macrophages for activation can potentially drive inflammation through dysregulated cytokine production. We will test this premise in a murine dorsal scald burn model in which sepsis will be induced at clinically relevant early and late time points after the initial burn injury. In the first aim, we will a) establish that bone marrow monocyte production is enhanced through flowcytometric analysis of monocytopoietic developmental antigens (ER-MP12 and 20) and clonogenic assays; b) measure plasma and bone marrow M-CSF levels; c) mRNA and cell surface expression of M-CSF receptor (c-fms) in total bone marrow cells and in different compartments of monocytic development; d) document the expression pattern of monocyte development associated transcription factors PU.1 and Egr-1 in different monocytopoietic compartments in burn and sepsis. In the second aim, using an in vitro monocytic differentiation of M1 cells, we will evaluate how different cytokines such as IL-1, IL-6 and IL-10 and the prostanoid PGE2 that are elevated in burn injury influence a) monocytic differentiation: b) c-fms expression; c) PU.l and Egr-1 activation and d) cytokine production and functions. In the third aim, we will determine if abrogation of the immunosuppressive and myelopoiesis regulating prostanoid, PGE2, can normalize monocytopoiesis, c-fms expression, PU.1 and Egr-1 expression and kinetics of monocyte release in our murine model. These studies will directly test our hypothesis and provide crucial information on the status and the mechanisms of monocytopoiesis in burn injury and sepsis. More importantly, these studies will help explain the aberrant cytokine production in severely injured burn patients and provide targets for rational therapies to improve their survival.