Therapeutic Targets in Acute Chest Syndrome

摘要 这个项目的目的是通过定义一个镰状细胞病(SCD)的 急性胸腔综合征(ACS)潜在的生存促进因素及其开发前景 作为一种分子疗法。急性冠脉综合征是主要的肺部并发症，也是导致过早死亡的常见原因。 在SCD。尽管经过了几十年的密集研究，但目前还没有针对急性冠脉综合征的特效治疗方法，因此它仍在继续 SCD的一个主要临床问题，特别是在非洲。我们最近发现，细胞外的血红素会触发 急性冠脉综合征参与Toll样受体4信号转导的炎症过程。越来越多的试验性、 临床和基因组学研究支持这一急性冠脉综合征发病模型，在该模型中，细胞外血红素触发 急性肺损伤。在这个新的R01项目中，我们测试了儿童表达超生理水平的新想法 血红素加氧酶-1(HO-1)是血红素降解的限速酶。我们假设高水平的HO-1在 儿童增强从血液循环中清除多余的血红素的能力，以改善他们的整体结局 来自ACS。在先导研究中，我们发现在成年SCD小鼠的血浆中补充HO-1可以改善ACS 生死存亡。这些先前的研究为理解内源性HO-1的产生提供了强有力的理论基础 在SCD中调节，并测试重组HO-1是否将有效地治疗临床前 模特。因此，在目标1中，我们将量化患有SCD的患者和转基因小鼠的血液HO-1表达，以及 检测miR-494表达是否影响外周血单个核细胞HO-1的表达 Ho-1基因Hmox1中高度保守的CpG位点的甲基化。我们会过度表达和敲门- 下调人外周血单个核细胞miR-494和敲除外周血HO-1活性 转基因SCD小鼠的单个核细胞，以确定这些遗传/表观遗传改变的直接影响 对血浆HO-1浓度的影响。我们将对SCD进行下一代全基因组测序 血HO-1水平极端水平的儿童识别新的全基因组序列(WGS)变体 该酶的活性不受年龄、miR-494和Hmox1甲基化的影响。在目标2中，我们将研究 加纳一大群SCD患者首次评估基线血液HO-1水平，miR-494 水平、Hmox1甲基化和WGS变异影响急性冠脉综合征的风险。在目标3中，我们将使用功能基因组学来 检测血细胞HO-1表达在提高急性冠脉综合征存活率中的重要性，并测试一种新型药物的疗效 截短重组HO-1分子从急性冠脉综合征中拯救转基因SCD小鼠此项目中的数据具有 有可能从根本上改变我们对人体如何适应循环构成的危险的理解 血红素对器官功能的影响。此外，它可能提供了一种机制来解释明显不同的急性冠脉综合征结果 在儿童和成人中，使用我们的小说可以迅速实施切实的治疗策略 HO-1生物菌株。

SUMMARY This project is aimed at improving the health of individuals who have sickle cell disease (SCD) by defining a potential pro-survival factor of acute chest syndrome (ACS), and exploring whether this factor can be developed as a molecular therapeutic. ACS is the leading pulmonary complication and a common cause of premature death in SCD. There is no specific treatment for ACS despite decades of intensive research, and so it continues to be a major clinical problem in SCD, particularly, in Africa. We recently discovered that extracellular heme triggers ACS in an inflammatory process involving toll-like receptor 4 signaling. A growing number of experimental, clinical and genomics studies support this model of ACS pathogenesis in which extracellular heme triggers the acute lung injury. In this new R01 project, we test the novel idea that children express supra-physiological levels of heme oxygenase-1 (HO-1), the rate-limiting heme degradation enzyme. We posit that the high-level HO-1 in children enhances their ability to clear excess heme from the blood circulation to improve their overall outcome from ACS. In pilot studies, we found that replenishing HO-1 in the plasma of adult SCD mice improved ACS survival. These prior research provide a strong rationale to understand how endogenous HO-1 production is regulated in SCD, and to test whether a recombinant HO-1 will be efficacious in treating ACS in a preclinical model. Thus, in Aim #1, we will quantify blood HO-1 expression in patients and transgenic mice with SCD, and examine whether HO-1 expression in peripheral blood mononuclear cells is influenced by miR-494 expression and methylation of a highly conserved CpG site in HMOX1 the HO-1 gene. We will over-express and knock- down miR-494 in human peripheral blood mononuclear cells, and knock-out HO-1 activity in peripheral blood mononuclear cells of transgenic SCD mice, to determine the direct effects of these genetic/epigenetic alterations on HO-1 concentration in the plasma. We will perform whole genome next generation sequencing of SCD children with extreme levels of blood HO-1 level to identify novel whole genome sequence (WGS) variants that influence activity of this enzyme independent of age, miR-494 and HMOX1 methylation. In Aim #2, we will study a large cohort of SCD patients in Ghana to assess for the first time whether baseline blood HO-1 level, miR-494 level, HMOX1 methylation and WGS variants influence ACS risk. In Aim #3, we will use functional genomics to test the importance of HO-1 expression in blood cells in improving ACS survival, and test the efficacy of a novel truncated recombinant HO-1 molecule to rescue transgenic SCD mice from ACS. Data from this project has the potential to fundamentally change our understanding of how the body naturalizes the danger posed by circulating heme on organ function. In addition, it may provide a mechanism to explain the markedly variable ACS outcome in children and adults, with a tangible therapeutic strategy that can be implemented expeditiously using our novel HO-1 biologic.