Therapeutic Targets in Acute Chest Syndrome

总结 该项目旨在通过定义一种治疗方法来改善镰状细胞病（SCD）患者的健康状况。 急性胸部综合征（ACS）的潜在促生存因子，并探讨该因子是否可以开发 作为分子治疗剂。ACS是主要的肺部并发症，也是过早死亡的常见原因 在SCD。尽管经过了几十年的深入研究，但没有针对ACS的特异性治疗方法， 这是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血红素会触发 ACS在炎症过程中涉及Toll样受体4信号传导。越来越多的实验， 临床和基因组学研究支持ACS发病机制的这一模型，其中细胞外血红素触发 急性肺损伤在这个新的R 01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。我们认为，高水平的HO-1在 儿童增强了他们从血液循环中清除过量血红素的能力，以改善他们的总体结果 ACS的。在初步研究中，我们发现补充成年SCD小鼠血浆中的HO-1可改善ACS 生存这些先前的研究为理解内源性HO-1的产生是如何 为了检测重组HO-1在临床前研究中是否能有效治疗ACS， 模型因此，在目标#1中，我们将定量SCD患者和转基因小鼠的血液HO-1表达， 检测外周血单个核细胞中HO-1的表达是否受miR-494表达的影响 以及HO-1基因HMOX 1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中的miR-494，并敲除外周血中的HO-1活性 转基因SCD小鼠的单核细胞，以确定这些遗传/表观遗传改变的直接影响 HO-1在血浆中的浓度。我们将进行SCD的全基因组下一代测序 血液HO-1水平极高的儿童，以确定新的全基因组序列（WGS）变异， 影响这种酶活性与年龄、miR-494和HMOX 1甲基化无关。在目标#2中，我们将研究 加纳SCD患者的大型队列，首次评估基线血液HO-1水平、miR-494 水平，HMOX 1甲基化和WGS变异影响ACS风险。在目标3中，我们将使用功能基因组学来 测试血细胞中HO-1表达在改善ACS存活率中的重要性，并测试新的 截短的重组HO-1分子拯救转基因SCD小鼠免于ACS。该项目的数据具有 有可能从根本上改变我们对身体如何自然化循环所构成的危险的理解。 血红素对器官功能的影响此外，它可能提供了一种机制，以解释显着可变ACS的结果 在儿童和成人，与有形的治疗策略，可以迅速实施，使用我们的新的 HO-1生物制剂。

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.