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: 6813434
• 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/6813434
• 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（由申请人提供）：辐射诱发的肺纤维化（RIPF）是胸部辐射的主要剂量限制毒性之一。 人们普遍认为，纤维化细胞因子 TGFbeta1 对于 RIPF 的发展是必需的，尽管这一假设尚未在动物模型中直接测试。 由于 TGFbeta1 以潜在形式分泌，因此 TGFbeta1 活性由激活步骤控制。 TGFbeta1 潜伏期是由于 TGFbeta1 与其前肽、潜伏相关肽 (LAP) 的相互作用所致。 TGFbeta1 信号传导发生在 LAP 释放 TGFbeta1 后。 我们发现 LAP 是上皮特异性整合素 alphavbeta6 的配体。 alphavbeta6 连接 LAP 后，TGFbeta1 被释放。 因此，通过表达 alphavbeta6，上皮细胞局部激活 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，我们培育了具有 TGFbeta1-LAP 敲入突变的小鼠，该突变消除了整合素结合（TGFbeta1-RGE 小鼠）。 这些小鼠的表型再现了 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（也许是唯一）机制。 我们还发现 beta6-/- 小鼠不会出现 RIPF。 此外，野生型小鼠在胸部照射后、即 RIPF 发作之前的晚期事件中急剧上调肺上皮中的 alphavbeta6 表达。 这些结果表明 alphavbeta6 介导的 TGFbeta1 激活是 RIPF 所必需的，并提出了 2 种治疗策略：抑制 alphavbeta6 功能和预防 alphavbeta6 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 3 个目标。 首先，我们将确认 TGFbeta1 是 RIPF 所必需的。 这将通过用 TGFbeta 拮抗剂治疗受辐射的小鼠以及测量 TGFbeta1+/- 小鼠的纤维化反应来完成。 其次，我们将测试 alphavbeta6 抑制剂（一种鼠抗 alphavbeta6 mAb）是否可以逆转和/或预防 RIPF。 如果这种试剂有效，它应该被视为治疗人类 RIPF 的潜在疗法，或许还可以治疗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 激活在 RIPF 中的作用。 第三，我们将检验以下假设：肺上皮中 alphavbeta6 的上调（发生在 RIPF 发生之前）是由于 TGFbeta1 信号传导增加所致。