avb6-mediated TGFb activation in radiation lung fibrosis

avb6介导的放射性肺纤维化中的TGFb激活

• 批准号: 6917903
• 负责人: John S Munger
• 金额: $ 42.25万
• 依托单位: NEW YORK UNIVERSITY SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-05 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6917903
• 关键词: biological signal transduction; blocking antibody; decorin; genetically modified animals; genotype; immunocytochemistry; immunoglobulin G; inflammation; integrins; intermolecular interaction; laboratory mouse; molecular pathology; monoclonal antibody; nucleic acid quantitation /detection; protein quantitation /detection; pulmonary fibrosis /granuloma; radiation therapy; radiobiology; receptor expression; recombinant proteins; respiratory epithelium; therapy adverse effect; transforming growth factors

DESCRIPTION (provided by applicant): Radiation-induced pulmonary fibrosis (RIPF) is one of the major dose-limiting toxicities of thoracic radiation. It is generally believed that the fibrogenic cytokine TGFbeta1 is necessary for the development of RIPF, although this hypothesis has not been directly tested in animal models. Because TGFbeta1 is secreted in a latent form, TGFbeta1 activity is controlled by an activation step. TGFbeta1 latency is due to interaction of TGFbeta1 with its propeptide, Latency-Associated Peptide (LAP). TGFbeta1 signaling occurs following release of TGFbeta1 from LAP. We discovered that LAP is a ligand for an epithelium-specific integrin, alphavbeta6. Following ligation of LAP by alphavbeta6, TGFbeta1 is released. Therefore, by expressing alphavbeta6, epithelial cells locally activate TGFbeta1. Mice lacking alphavbeta6 (beta6-/- mice) do not develop lung fibrosis after exposure to bleomycin. Recently, we generated mice with a knocked-in mutation in TGFbeta1-LAP that abrogates integrin binding (TGFbeta1-RGE mice). The phenotype of these mice reproduces that of TGFbeta1-/- mice, indicating that integrin-mediated TGFbeta1 activation is a major (and perhaps the only) mechanism for generating active TGFbeta1. We have also found that beta6-/- mice do not develop RIPF. Furthermore, wild type mice sharply upregulate alphavbeta6 expression in lung epithelium as a late event after thoracic irradiation, just prior to the onset of RIPF. These results suggest that alphavbeta6-mediated TGFbeta1 activation is required for RIPF, and suggest 2 treatment strategies: inhibition of alphavbeta6 function, and prevention of alphavbeta6 upregulation. Our overall goal is to treat and/or prevent RIPF by inhibiting the alphavbeta6-TGFbeta1 activation system. We propose 3 aims. First, we will confirm that TGFbeta1 is required for RIPF. This will be done by treating irradiated mice with a TGFbeta antagonist and also by measuring the fibrotic response of TGFbeta1+/- mice. Second, we will test whether an alphavbeta6 inhibitor (a murine anti-alphavbeta6 mAb) reverses and/or prevents RIPF. If this reagent works, it should be considered as a potential therapy in human RIPF, and perhaps in radiation fibrosis affecting other organs. Measuring the fibrotic response of TGFbeta1-RGE+/- mice will also test the role of integrin-mediated TGFbeta1 activation in RIPF. Third, we will test the hypothesis that alphavbeta6 upregulation in lung epithelium, which occurs just prior to the development of RIPF, is due to increased TGFbeta1 signaling.

描述(申请人提供)：放射性肺纤维化(RIPF)是胸部辐射的主要剂量限制性毒性之一。一般认为，纤维化细胞因子TGFbeta1在RIPF的发生发展中是必需的，尽管这一假说尚未在动物模型中直接验证。由于TGFbeta1以潜伏的形式分泌，因此TGFbeta1的活性受激活步骤的控制。TGFbeta1潜伏期是由于TGFbeta1与其前肽-潜伏期相关肽(LAP)的相互作用所致。TGFbeta1信号发生在TGFbeta1从LAP释放之后。我们发现LAP是一种上皮特异性整合素的配体，即αvbeta6。αvbeta6结扎LAP后，释放TGFbeta1。因此，通过表达αvbeta6，上皮细胞局部激活了TGFbeta1。缺乏Alphavbeta6的小鼠(Beta6-/-小鼠)在接触博莱霉素后不会出现肺纤维化。最近，我们产生了TGFbeta1-LAP敲入突变取消整合素结合的小鼠(TGFbeta1-RGE小鼠)。这些小鼠的表型复制了TGFbeta1-/-小鼠的表型，表明整合素介导的TGFbeta1激活是产生活性TGFbeta1的主要(也可能是唯一的)机制。我们还发现，Beta6-/-小鼠不会发生RIPF。此外，野生型小鼠在胸部照射后，就在RIPF开始之前，肺上皮细胞中αvbeta6的表达急剧上调，这是一个晚期事件。这些结果表明，RIPF需要αvbeta6介导的TGFbeta1的激活，并提出了两种治疗策略：抑制alphavbeta6的功能，防止alphavbeta6的上调。 我们的总体目标是通过抑制Alphavbeta6-TGFbeta1激活系统来治疗和/或预防RIPF。我们提出了三个目标。首先，我们将确认RIPF需要TGFbeta1。这将通过用TGFbeta拮抗剂治疗受辐射的小鼠和通过测量TGFbeta1+/-小鼠的纤维化反应来实现。其次，我们将测试Alphavbeta6抑制剂(一种鼠抗Alphavbeta6单抗)是否逆转和/或阻止RIPF。如果这种试剂有效，它应该被认为是一种潜在的治疗人类RIPF的方法，也许还可以用于影响其他器官的放射性纤维化。测量TGFbeta1-RGE+/-小鼠的纤维化反应也将测试整合素介导的TGFbeta1在RIPF中的作用。第三，我们将检验这一假设，即在RIPF发生之前，肺上皮细胞中αvbeta6的上调是由于TGFbeta1信号的增加。