The Pharmacology of Dermal Fibrosis

描述(申请人提供)：基质更换和修复是伤口愈合所必需的，但当修复过程过于活跃时，如疤痕或瘢痕疙瘩形成，或发生不当时，如硬皮病和其他纤维性疾病，可导致发病率，对于硬皮病，可导致死亡。虽然生长因子在纤维化中起着核心作用，但小分子在病理性纤维化中的作用还没有得到很好的探讨。我们最近已经证明，嘌呤核苷腺苷通过腺苷A2a受体，在实验性肝硬化和硬皮病模型中的纤维化发展中发挥核心作用。我们建议进一步确定腺苷和腺苷受体是否在病理纤维化中起作用，并剖析成纤维细胞上腺苷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，我们建议研究：1.腺苷受体在病理性纤维化中的作用。我们将在博莱霉素诱导的皮肤瘢痕和弥漫性真皮纤维化模型中研究增生性瘢痕的发展；在野生型、腺苷A1、A2A、A2B和A3受体敲除小鼠，产生较少细胞外腺苷的小鼠(胞外5‘核苷酸酶和核苷三磷酸焦磷酸酶敲除小鼠)和接受腺苷受体拮抗剂治疗的小鼠中；ii.腺苷A2A受体的纤维化信号传递在初步实验中，我们观察到腺苷A2A受体的刺激减少了核FlI1的水平，这是CTGF表达的结构性抑制因子，这一变化可能介导了腺苷和A2A受体的促纤维化作用。我们将结合药理学和siRNA介导的基因敲除技术，剖析从腺苷A2a受体到抑制FLI1表达和核定位的信号通路；iii.腺苷A2a受体和“抗纤维化”细胞因子受体之间的串扰我们以前已经证明，作为一种抗纤维化细胞因子，干扰素-3可以减少腺苷A2a受体的表达，并更显著地发挥作用。我们将用药理学和分子(siRNA介导的基因敲除)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中，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带到临床上。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，在从硬皮病(可能危及生命的弥漫性皮肤和器官纤维化)到毁容疤痕或肌腱增大的各种情况下，过度的纤维组织形成是一个重大的医学问题。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。我们建议进行研究，以进一步证实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导致的医学问题可以促进新药物的开发，这些药物将防止扩大的疤痕发展或改善以硬皮病为特征的纤维化。

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.