Experimental models of scleroderma pathogenesis

描述(由申请人提供)：我们寻求促进硬皮病成纤维细胞过度产生胶原蛋白的机制的了解。硬皮病是一种临床上异质性的结缔组织疾病，以血管、免疫/炎症和纤维化为特征。尽管付出了很多努力，但目前还没有有效的治疗方法和可靠的诊断/预后工具来管理组织纤维化的进展，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，即针对PDGF受体(PDGFR)的循环自身抗体与SSC成纤维细胞的促纤维化表型存在因果关系。具体地说，我们已经证明了抗PDGFR自身抗体只存在于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的标志包括过度的ROS产生，Ha-RAS的稳定，PDGFR水平的增加，以及通过依赖于转化生长因子-2激活Smad3而放大I型胶原的转录。我们假设了一种疾病机制，即抗PDGFR自身抗体触发ROS驱动的信号级联反应，促进转化生长因子-2、PDGFR和胶原蛋白的无竞争产生。我们的模型与先前发现的PDGFR升高与SSC真皮损伤和移植成纤维细胞中的转化生长因子-2活性降低有关。这也与RAS和Smad信号之间的功能关系以及对PDGF和TGF-2信号的相互正调控的证据是一致的。我们建议对抗PDGFR自身抗体的关键下游事件和致病特性进行表征。虽然前者的目标将使用传统的细胞培养系统来实现，而后者将使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，也可能发现更有效地管理组织纤维化的新的治疗机会。 与公共卫生相关：硬皮病是一种相对罕见的疾病，通常是致命的，主要影响成年女性。死亡是由皮肤、血管和内脏结缔组织的大量纤维化引起的终末期器官衰竭造成的。目前还没有有效的治疗方法或可靠的预后工具来管理疾病的进展，主要是由于我们对硬皮病发病机制的了解有限。我们最近发现，抗PDGFR受体(PDGFR)的循环自身抗体可能是硬皮病成纤维细胞促纤维化表型的主要决定因素。本申请寻求进一步表征抗PDGFR自身抗体的关键机制和致病特性，长期目标是开发针对这种破坏性疾病的新的靶向疗法。

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.