EMAP II: Pulmonary Vascular Mediator

描述（由申请人提供）：血管生成是肺形态发生的重要过程。血管破裂可导致肺泡异常，通常是致命的，如早产儿中发现的支气管肺发育不良（BPD）。在人类和动物模型中的BPD研究表明，肺发育不全与重要血管介质血管内皮生长因子（VEGF）及其受体（VEGFR）的表达和信号传导受损之间存在直接联系。使用VEGF单一疗法不足以挽救肺形态发生，因为下游VEGF信号传导仍然被破坏。鉴定VEGFR信号转导的调节因子对于开发BPD的新治疗策略至关重要。我们最近取得了许多发现，表明有效的抗血管生成蛋白和促炎介质内皮-单核细胞激活多肽（EMAP）II在发育中的肺中作为肺血管形成的可能指导者发挥作用：A）其肺部表达与血管形成期呈负相关，B）我们的初步数据表明，在BPD的人和动物模型中，EMAP II表达在肺上皮和巨噬细胞中显著升高，和C）外源性EMAP II的递送严重破坏肺泡-毛细血管生长，而我们的初步数据表明EMAP II功能阻断抗体挽救远端肺泡生长。从机制上讲，我们证明EMAP II通过<$5 <$1整合素抑制内皮细胞粘附，并阻断血管内皮生长因子受体II（VEGFR2）信号传导。虽然EMAP II调节VEGFR2信号传导的机制尚不清楚，但最近的研究表明，EMAP II通过SMURF2（Smad特异性泛素调节因子2）靶向TGF受体进行泛素化和降解来调节TGF受体。除了EMAP II的抗血管生成特性外，EMAP II还通过刺激巨噬细胞迁移和TNF？分泌促进促炎反应。我们推测BPD中EMAP II表达升高通过SMURF2/VEGFR2依赖性方式抑制血管发育，从而抑制远端肺泡发育。我们的具体目标是：1）确定上皮和巨噬细胞EMAP II对BPD中血管抑制的贡献; 2）确定EMAP II抗血管生成抑制是否是VEGFR2/SMURF2介导的机制;和3）确定EMAP II功能阻断抗体的雾化递送在挽救BPD中血管形成中的治疗潜力。我们的具体目标的成功实现将建立支持EMAP II在BPD中的作用的科学证据，并允许设计一种增强肺血管化的多药物治疗方法。此外，EMAP II在BPD中的显著升高可能将其表达确定为可测量的风险因素，使其能够作为早产儿的预后指标。

DESCRIPTION (provided by applicant): Angiogenesis is an essential process in pulmonary morphogenesis. Vascular disruption can lead to alveolar abnormalities that are often fatal, such as Bronchopulmonary Dysplasia (BPD) found in premature infants. BPD studies in humans and animal models demonstrate a direct link between lung hypoplasia and impaired expression and signaling of the essential vascular mediator Vascular Endothelial Growth Factor (VEGF) and its receptors (VEGFR). Therapy using VEGF monotherapy is insufficient to rescue lung morphogenesis, as downstream VEGF signaling remains disrupted. Identifying regulators of VEGFR signaling is crucial to develop new therapeutic strategies for BPD. We recently made numerous discoveries indicating that the potent anti-angiogenic protein and proinflammatory mediator Endothelial-Monocyte Activating Polypeptide (EMAP) II functions as a likely director of pulmonary vascular formation in the developing lung as: A) its pulmonary expression is inversely correlated to periods of vascularization, B) our preliminary data indicates that EMAP II expression is markedly elevated in pulmonary epithelium and macrophages in human and animal models of BPD, and C) delivery of exogenous EMAP II profoundly disrupts alveolar-capillary growth while our preliminary data indicates that an EMAP II function blocking antibody rescues distal alveolar growth. Mechanistically, we demonstrated that EMAP II inhibits endothelial cell adhesion via ¿5¿1 integrin, and blocks vascular endothelial growth factor receptor II (VEGFR2) signaling. Although the mechanism by which EMAP II regulates VEGFR2 signaling is unknown, recent work suggests that EMAP II modulates the TGF receptor by targeting it for ubiquitination and degradation via SMURF2 (Smad specific ubiquitin regulatory factor 2). In addition to EMAP II's anti-angiogenic properties, EMAP II also promotes proinflammatory responses via stimulation of macrophage migration and TNF¿ secretion. We hypothesize that elevated expression of EMAP II in BPD results in inhibition of vascular development through a SMURF2 / VEGFR2 dependent manner that results in suppression of distal alveolar development. Our specific aims are to: 1) determine the contribution of epithelial and macrophage EMAP II to vascular inhibition in BPD; 2) determine if EMAP II anti-angiogenic inhibition is a VEGFR2 / SMURF2 mediated mechanism; and 3) determine therapeutic potential for aerosolized delivery of an EMAP II function blocking antibody in rescuing blood vessel formation in BPD. Successful accomplishment of our specific aims will establish the scientific evidence supporting EMAP II's role in BPD and allow design of a multi-drug therapeutic approach that will enhance pulmonary vascularization. Furthermore, EMAP II's marked elevation in BPD may identify its expression as a measurable risk factor allowing it to serve as a prognostic indicator in premature infants.