The Pharmacology of Dermal Fibrosis

描述（由申请人提供）：伤口愈合需要基质替代和修复，但当过程过度活跃时，如疤痕或瘢痕疙瘩形成，或当不适当发生时，如硬皮病和其他纤维化疾病，它可能导致发病率，在硬皮病的情况下，死亡。虽然生长因子在纤维化中起核心作用是明确的，但小分子在病理性纤维化中的作用尚未得到很好的探讨。我们最近证明，嘌呤核苷腺苷通过腺苷A2A受体起作用，在肝硬化和硬皮病实验模型中发生的纤维化中起核心作用。我们建议进一步确定腺苷和腺苷受体是否在病理性纤维化中发挥作用，并剖析成纤维细胞上的腺苷A2A受体刺激胶原和其他基质成分过度产生的分子机制。为此，我们提出研究：1 .腺苷受体在病理性纤维化中的作用。我们将在野生型、腺苷A1、A2A、A2B和A3受体敲除小鼠、细胞外腺苷产生较少的小鼠（外胞5核苷酸酶和核苷三磷酸焦磷酸酶敲除小鼠）和腺苷受体拮抗剂小鼠中，研究博来霉素治疗引起的皮肤瘢痕和弥漫性真皮纤维化模型中增生性瘢痕的发展；2。在初步实验中，我们观察到腺苷A2A受体刺激会降低核fli1水平，这是CTGF表达的组成抑制因子，这种变化可能介导腺苷和A2A受体的促纤维化作用。我们将剖析从腺苷A2A受体到抑制fli1表达和核定位的信号通路，使用药理学和sirna介导的敲低技术相结合；3。腺苷A2A受体和“抗纤维化”细胞因子受体之间的交叉对话我们之前已经证明，干扰素-3，一种抗纤维化细胞因子，减少腺苷A2A受体的表达，更显著地，减少功能。我们将采用药理学和分子（sirna介导的敲低）相结合的方法研究干扰素-3下调腺苷A2A受体功能的机制。在未来的实验中，我们将研究腺苷受体在瘢痕疙瘩形成和其他临床相关形式的病理性纤维化（如放射性纤维化）中的作用。由于腺苷受体拮抗剂正在开发用于治疗各种疾病，因此有可能将这些研究中获得的信息迅速应用于临床。公共卫生相关性：新纤维组织的合成是一个正常的过程，对伤口愈合和组织修复至关重要，然而，在硬皮病（弥漫性皮肤和器官纤维化，可能危及生命）、毁容疤痕或肌腱扩大等疾病中，纤维组织的过量形成是一个重要的医学问题。我们的实验室发现腺苷及其受体在硬皮病和增生性瘢痕动物模型的弥漫性纤维化中起核心作用。我们建议进一步研究腺苷及其受体在瘢痕形成中的作用，并发现腺苷受体刺激多余纤维组织产生的机制。更好地了解腺苷及其受体在纤维化中的作用以及纤维化引起的医学问题，可能有助于开发新的药物，防止瘢痕扩大或改善硬皮病特征纤维化。

DESCRIPTION (provided by applicant): Matrix replacement and repair is required for wound healing but when the process is overly exuberant, as in scar or keloid formation, or when it occurs inappropriately, as in Scleroderma and other fibrosing diseases, it can lead to morbidity and, in the case of Scleroderma, mortality. Although it is clear that growth factors play a central role in fibrosis the role of small molecules in pathologic fibrosis has not been well explored. We have recently demonstrated that the purine nucleoside adenosine, acting through the adenosine A2A receptor, plays a central role in the fibrosis that develops in experimental models of hepatic cirrhosis and scleroderma. We propose here to further determine whether adenosine and adenosine receptors play a role in pathologic fibrosis and to dissect the molecular mechanism by which adenosine A2A receptors on fibroblasts stimulate overproduction of collagen and other matrix constituents. To this end we have proposed to study: I. The role of adenosine receptors in pathologic fibrosis. We will study the development of hypertrophic scarring in a model of dermal scarring and diffuse dermal fibrosis induced by bleomycin treatment in wild type, adenosine A1, A2A, A2B and A3 receptor knockout mice, mice that generate less extracellular adenosine (ecto-5'Nucleotidase and nucleoside triphosphate pyrophosphatase knockout mice) and mice treated with adenosine receptor antagonists; II. Signaling at adenosine A2A receptors for fibrosis In preliminary experiments we have observed that adenosine A2A receptor stimulation diminishes nuclear fli1 levels, a constitutive repressor of CTGF expression, a change which may mediate the pro- fibrotic effects of adenosine and the A2A receptor. We will dissect the signaling pathways from adenosine A2A receptors to suppression of fli1 expression and nuclear localization using a combination of pharmacologic and siRNA-mediated knockdown techniques; III. Cross-talk between adenosine A2A receptors and receptors for "anti-fibrotic" cytokines We have previously demonstrated that interferon-3, an anti-fibrotic cytokine, diminishes adenosine A2A receptor expression and, more dramatically, function. We will study the mechanism by which interferon-3 downregulates adenosine A2A receptor function with a combination of pharmacologic and molecular (siRNA-mediated knockdown) methods. In future experiments we will examine the role of adenosine receptors in keloid formation and other clinically- relevant forms of pathologic fibrosis (e.g. radiation fibrosis). Because adenosine receptor antagonists are under development for the treatment of a variety of medical conditions it may be possible to quickly bring the information garnered in these studies to the clinic. PUBLIC HEALTH RELEVANCE: The synthesis of new fibrous tissue is a normal process which is critical for wound healing and tissue repair, however excess fibrous tissue formation is a significant medical issue in conditions ranging from Scleroderma (diffuse skin and organ fibrosis that can be life-threatening) to disfiguring scarring or tendon enlargement. Our laboratory has found that adenosine and its receptors play a central role in diffuse fibrosis in animal models of Scleroderma and hypertrophic scarring. We propose studies designed to further confirm the role of adenosine and its receptors in scarring and to discover the mechanism by which adenosine receptors stimulate production of excess fibrous tissue. A better understanding of the role of adenosine and its receptors in fibrosis and the medical problems resulting from fibrosis could facilitate the development of new agents that will prevent the development of enlarged scars or ameliorate the fibrosis that characterizes Scleroderma.