Fibroblast control of TGF-beta activation by Thy-1 and lung fibrosis

Thy-1 成纤维细胞对 TGF-β 激活的控制和肺纤维化

• 批准号: 7176258
• 负责人: JOANNE E MURPHY-ULLRICH
• 金额: $ 18.13万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-02-01 至 2009-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7176258
• 关键词: Fibroblast; control; TGF; beta; activation

DESCRIPTION (provided by applicant): Idiopathic pulmonary fibrosis is a rare and progressive, fatal disease for which there is no effective treatment. Dysregulated wound healing by subsets of fibrogenic lung fibroblasts leads to fibrosis in idiopathic pulmonary fibrosis. TGF-( is a key regulator of wound healing responses and its action is critical for fibrogenic progression. TGF-( must be activated from its latent state to affect these responses. Our data show that one of the differential characteristics of fibroblast subsets is the capacity to activate latent TGF-( in response to injury. The presence of the GPI-anchored protein, Thy-1, on lung fibroblasts limits the ability to activate TGF-(. These data suggest that Thy-1 is a biological response modifier which limits TGF-( activation. Thy-1 (-) fibroblasts express higher levels of the latent TGF-( binding protein 4 (LTBP-4) when stimulated with bleomycin than do Thy-1 (+) cells, consistent with the increased TGF-( activity in the lungs of LTBP-4 hypomorphic mice. Thy-1 (-) LTBP-4 hypomorphic lung fibroblasts fail to activate latent TGF-( in response to bleomycin, suggesting that LTBP-4 is necessary for the ability of Thy-1 (-) cells to respond. Since TGF-( activity is critical to the fibrogenic progression of pulmonary fibrosis, the capacity of interstitial fibroblasts to activate latent TGF-( could be a key determinant of either benign resolution of lung injury or the development of fibrotic complications. We hypothesize that the ability of pulmonary fibroblasts to activate latent TGF-( in response to stimulation is critical to fibrogenic progression following lung injury. Thus fibroblasts with attenuated TGF-( activation would favor limited wound healing responses, whereas, fibroblasts that exhibit robust TGF-( activation in response to injury would favor fibrogenic responses. The overall goal of this proposal is to determine how modulating TGF-( activation by lung fibroblasts affects progression of pulmonary fibrosis. We will use a novel strategy that employs a modified adenovirus and a fibroblast-specific promoter to drive fibroblast specific transgene expression of Thy-1 and LTBP-4 in vivo to test the effects of fibroblast-specific expression of these proteins on fibrogenic progression in a mouse model of bleomycin-induced pulmonary fibrosis. We propose the following aims: Specific Aim 1: To test the hypothesis that fibroblast-specific over-expression of Thy-1 protects from bleomycin-induced pulmonary fibrosis by limiting TGF-( activation and to determine if expression of constitutively active TGF-( abrogates the potential protective effects of Thy-1 overexpression; Specific Aim 2: To test the hypothesis that fibroblast expression of LTBP-4 is necessary for activation of latent TGF-( in vitro and whether LTBP-4 abrogates Thy-1 protection in vivo. These studies will provide new insights into how lung fibroblast subpopulations determine fibrogenic progression and potentially identify new therapeutic approaches to treat idiopathic pulmonary fibrosis.

描述（申请人提供）：特发性肺纤维化是一种罕见的、进行性的、致命的疾病，目前尚无有效的治疗方法。在特发性肺纤维化中，由纤维化肺成纤维细胞亚群引起的伤口愈合失调导致纤维化。TGF-β是伤口愈合反应的关键调节因子，其作用对于纤维化进展至关重要。TGF-β必须从其潜伏状态激活以影响这些反应。我们的数据表明，成纤维细胞亚群的差异特征之一是激活潜在的TGF-β的能力，以响应损伤。肺成纤维细胞上GPI锚定蛋白Thy-1的存在限制了活化TGF-β的能力。这些数据表明Thy-1是限制TGF-β活化的生物反应调节剂。当用博莱霉素刺激时，Thy-1（-）成纤维细胞比Thy-1（+）细胞表达更高水平的潜伏性TGF-β结合蛋白4（LTBP-4），这与LTBP-4低形态小鼠肺中增加的TGF-β活性一致。Thy-1（-）LTBP-4低形态肺成纤维细胞不能激活潜在的TGF-β 1对博莱霉素的反应，表明LTBP-4是Thy-1（-）细胞反应能力所必需的。由于TGF-β活性对肺纤维化的纤维化进展至关重要，间质成纤维细胞激活潜伏TGF-β的能力可能是肺损伤良性消退或纤维化并发症发展的关键决定因素。我们假设肺成纤维细胞激活潜在TGF-β 1的能力是肺损伤后纤维化进展的关键。因此，具有减弱的TGF-β活化的成纤维细胞将有利于有限的伤口愈合反应，而响应于损伤而表现出稳健的TGF-β活化的成纤维细胞将有利于纤维发生反应。该提案的总体目标是确定调节肺成纤维细胞的TGF-β活化如何影响肺纤维化的进展。我们将使用一种新的策略，采用修饰的腺病毒和成纤维细胞特异性启动子驱动成纤维细胞特异性转基因表达的Thy-1和LTBP-4在体内测试这些蛋白质的成纤维细胞特异性表达对博莱霉素诱导的肺纤维化小鼠模型中的纤维化进展的影响。我们提出以下目标：具体目标1：为了检验Thy-1的成纤维细胞特异性过表达通过限制TGF-β活化来防止博莱霉素诱导的肺纤维化的假设，并确定组成型活性TGF-β的表达是否消除了Thy-1过表达的潜在保护作用;具体目的2：为了检验LTBP-4的成纤维细胞表达是体外激活潜伏性TGF-β所必需的假设，以及LTBP-4是否废除体内Thy-1保护。这些研究将为肺成纤维细胞亚群如何决定纤维化进展提供新的见解，并可能确定治疗特发性肺纤维化的新治疗方法。