Experimental models of scleroderma pathogenesis

描述（由申请人提供）：我们寻求进一步了解硬皮病成纤维细胞产生过多胶原蛋白的机制。硬皮病（系统性硬化症，SSc）是一种临床异质性的结缔组织疾病，其特征是血管、免疫/炎症和纤维化表现。尽管付出了很多努力，但目前既没有有效的治疗方法，也没有可靠的诊断/预后工具来控制组织纤维化的进展，而组织纤维化是SSc发病率和死亡率的主要原因。我们基于令人兴奋的新证据，即循环中针对PDGF受体（PDGFR）的自身抗体与SSc成纤维细胞的促纤维化表型有因果关系。具体来说，我们已经证明抗pdgfr自身抗体仅存在于SSc血清中，并且它们可以将健康的成纤维细胞转化为SSc样细胞。已确定的成纤维细胞激活标记包括活性氧（ROS）产生过多、Ha-Ras稳定、PDGFR水平升高以及通过TGF-2独立激活Smad3而扩增的I型胶原转录。我们假设一种疾病机制，即抗PDGFR自身抗体触发ros驱动的信号级联，促进TGF-2、PDGFR和胶原蛋白的无对抗产生。我们的模型与先前的发现一致，即在SSc皮肤病变和外植成纤维细胞中，PDGFR升高与TGF-2活性失调有关。这也与Ras和Smad信号之间的功能关系以及PDGF和TGF-2信号相互正向调节的证据一致。我们建议描述抗pdgfr自身抗体的关键下游事件和致病特性。前者的目标将采用传统的细胞培养系统，后者将采用一种新的皮肤纤维化动物模型。完成这些研究将提高我们对SSc发病机制的理解，也可能确定新的治疗机会，以更有效地管理组织纤维化。

DESCRIPTION (provided by applicant): We seek to advance knowledge of the mechanisms responsible for excessive collagen production by scleroderma fibroblasts. Scleroderma (Systemic Sclerosis; SSc) is a clinically heterogeneous and poorly understood disorder of the connective tissue that is characterized by vascular, immune/inflammatory and fibrotic manifestations. In spite of much effort, there are currently neither effective therapies nor reliable diagnostic/prognostic tools to manage the progression of tissue fibrosis, the main cause of morbidity and mortality in SSc. We base this application on exciting new evidence that circulating auto-antibodies against the PDGF receptor (PDGFR) are causally associated with the pro-fibrotic phenotype of SSc fibroblasts. Specifically, we have shown that anti-PDGFR auto-antibodies are only present in SSc sera, and that they can convert healthy fibroblasts into SSc-like cells. Identified markers of fibroblasts activation include excessive reactive oxygen species (ROS) production, Ha-Ras stabilization, increased PDGFR levels, and amplified collagen I transcription through TGF-2 independent activation of Smad3. We hypothesize a disease mechanism whereby anti-PDGFR auto-antibodies trigger a ROS-driven signaling cascade that promotes unopposed production of TGF-2, PDGFR, and collagen. Our model is in line with previous findings of elevated PDGFR in association with deregulated TGF-2 activity in SSc dermal lesions and explanted fibroblasts. It is also consistent with evidence of functional relationships between Ras and Smad signals, and reciprocally positive regulation of PDGF and TGF-2 signals. We propose to characterize key downstream events and pathogenic properties of the anti-PDGFR auto-antibodies. Whereas the former aim will be pursued using traditional cell culture systems, the latter one will employ a novel animal model of skin fibrosis. Completing these studies will improve our understanding of SSc pathogenesis, and may also identify novel therapeutic opportunities to manage tissue fibrosis more effectively. PUBLIC HEALTH RELEVANCE: Scleroderma is a relatively rare and often fatal disorder that affects mostly adult women. Death occurs from end-stage organ failure caused by massive fibrosis in the connective tissue of skin, vessels and internal organs. There are currently neither effective therapies nor reliable prognostic tools to manage disease progression, mostly due to our limited understanding of scleroderma pathogenesis. We have recently discovered that circulating auto-antibodies against PDGFR receptor (PDGFR) may represent a main determinant of the pro-fibrotic phenotype of scleroderma fibroblasts. The present application seeks to further characterize key mechanisms and pathogenic properties of anti-PDGFR auto-antibodies, with the long-term goal of developing new targeted therapies against this devastating disorder.