Role of ADAM17 in MDSC-Mediated Development of Pulmonary Hypertension

项目摘要 虽然已知通过抑制趋化因子受体CXCR 2减少白细胞募集 在小鼠疾病模型中减弱肺动脉高压（PH）的发展-并且激活PEP- 酶ADAM 17水平与改善血管重塑相关--ADAM 17在CXCR 2中的作用-- 介导的髓样细胞运输导致PH的发展是未知的。迫切需要关闭 这种知识上的差距，因为，直到完成，免疫调节髓源性抑制， 分选细胞（MDSC）在肺血管疾病发展中的作用仍然是遥不可及的。的 所提出的实验的总体目标是确定ADAM 17在多晶型中的贡献， 肺血管系统内MDSC（PMN-MDSC）募集。核心假设是减少的ADAM 17 PMN-MDSC的表达和活性对于将这些细胞募集到肺血管系统是必需的 这一假说的科学前提是在初步数据的基础上制定的 这表明表达CXCR 2的PMN-MDSC对于PH的动物模型中的PH的发展是必需的。 这种循环细胞群在IPF患者的全血中以更高的程度存在。 此外，ADAM 17水平与CXCR 2表达呈负相关，并与发育相关。 拟议研究的理由是，研究完成后， 将当前MDSC靶向治疗应用于疾病预防和治疗，并告知潜在危害 使用ADAM 17靶向治疗其他疾病。中心假设将通过以下方式进行检验： 以下具体目的：1）测试假设，ADAM 17的表达和功能活性是差异的， 在分离自PH和特发性肺纤维化（IPF）患者的PMN-MDSC中调节，和2）检测 假设PMN-MDSC表达的ADAM 17可防止病理性肺血管重塑- ing.在第一个目标中，将采集伴和不伴PH的IPF患者的外周血样本， 基于流式细胞术分析， MDSC子类型。然后将表征细胞群体以用于鉴定的生物标志物的等位基因区分 候选人，除了评估ADAM 17功能活性，包括脱落和蛋白水解活性。 在第二个目的中，在骨髓来源的细胞中缺失ADAM 17的野生型和转基因小鼠（LysM.Cre. ADAM 17 fl/fl小鼠）将用于确定组织特异性基因表达对发育的影响。 在两种疾病模型（博来霉素诱导的肺纤维化和慢性缺氧）中的PH值。在com- 因此，本研究的贡献将是重大的，因为它代表了一种可翻译的策略，以提高 通过预防MDSC运输到肺部的临床结果。这项研究是创新的，因为- 因为它代表了从现状的实质性偏离，将重点从血管扩张剂治疗转移到 在继发于IPF的PH的病理生物学中微调的免疫调节介质MDSC。

PROJECT SUMMARY While it is known that a reduction in leukocyte recruitment through inhibition of chemokine receptor CXCR2 attenuates development of pulmonary hypertension (PH) in murine models of disease – and that activated pep- tidase ADAM17 levels are associated with improved vascular remodeling – the role of ADAM17 in CXCR2- mediated myeloid cell trafficking leading to the development of PH is unknown. There is an urgent need to close this gap in knowledge because, until accomplished, immunotherapeutic modulation of myeloid-derived suppres- sor cell (MDSC) contribution to the development of pulmonary vascular disease will remain beyond reach. The overall objective of the proposed experiments is to define the contribution of ADAM17 in polymorphonuclear- MDSC (PMN-MDSC) recruitment within the lung vasculature. The central hypothesis is that reduced ADAM17 expression and activity by PMN-MDSC is necessary for recruitment of these cells to the pulmonary vasculature leading to PH. The scientific premise for this hypothesis has been formulated on the basis of preliminary data demonstrating that PMN-MDSC expressing CXCR2 are necessary for development of PH in animal models of disease, and that this circulating cell population is present to a higher degree in whole blood of IPF patients. Additionally, ADAM17 levels inversely correlate with CXCR2 expression, and are associated with development of severe PH. The rationale for the proposed research is that, upon completion of the studies it will be possible to apply current MDSC-targeted therapies to disease prevention and treatment, as well as inform potential harms in the use of ADAM17-targeted treatments for other diseases. The central hypothesis will be tested by pursuing the following specific aims: 1) test the hypothesis that ADAM17 expression and functional activity is differentially regulated in PMN-MDSC isolated from patients with PH and idiopathic pulmonary fibrosis (IPF), and 2) test the hypothesis that ADAM17 expression by PMN-MDSC protects against pathologic pulmonary vascular remodel- ing. In the first aim, peripheral blood samples from patients with IPF with and without PH will be collected, in order to define a MDSC profile in patients with disease and controls, based upon flow cytometric analysis for MDSC sub-types. Cell populations will then be characterized for allelic discrimination of an identified biomarker candidate, in addition to assessment of ADAM17 functional activity, including shedding and proteolytic activity. In the second aim, wild type and transgenic mice with deletion of ADAM17 in myeloid-derived cells (LysM.Cre- ADAM17fl/fl mice) will be used to determine the effect tissue-specific gene expression will have on the develop- ment of PH in two models of disease (bleomycin-induced pulmonary fibrosis and chronic hypoxia). Upon com- pletion, the contribution of this study will be significant because it represents a translatable strategy to improve clinical outcomes through prevention of MDSC trafficking to the lung. The proposed research is innovative be- cause it represents a substantive departure from the status quo by shifting focus from vasodilator therapy to a fine-tuned immunoregulatory mediator, MDSC, in the pathobiology of PH secondary to IPF.