Role of SCARF1 in Human Lupus

描述（由申请人提供）：有效检测和清除凋亡细胞对于维持耐受性和组织稳态至关重要。我们最近通过与死细胞上的C1q/磷脂酰丝氨酸复合物的相互作用，发现内皮细胞-1上表达的清零受体（SCARF1）是树突状细胞上凋亡细胞的受体（Ramirez-Ortiz等；Nature Immunology）。在体外和体内，SCARF1的缺失导致凋亡细胞的摄取受损，细胞尸体在组织和血液中积累。因此，SCARF1缺陷小鼠发展为狼疮样自身免疫性疾病。在这项应用中，我们建议研究人类SCARF1在SLE发病和发展中的作用。这是理解SCARF1在凋亡细胞清除、维持耐受性和预防自身免疫中的作用的下一个合乎逻辑的步骤。我们拟：1)通过qRT-PCR、流式细胞术和ImageStream检测SLE患者是否存在SCARF1表达失调导致凋亡细胞识别和清除缺陷；2)通过生化和成像技术确定SCARF1与凋亡细胞的相互作用；3)利用T细胞增殖试验、细胞因子分泌的Luminex分析和共聚焦成像技术，表征C1q和/或凋亡细胞激活SCARF1在树突状细胞信号传导、成熟和抗原呈递中的作用。我们使用健康志愿者细胞的初步数据显示，SCARF1在单核细胞和树突状细胞上高度表达。我们预计SLE患者免疫细胞中的SCARF1表达将下调，加剧和/或解释这些患者中循环凋亡细胞数量的增加。SLE的病因尚不清楚，但已知疾病的发展是由于细胞凋亡失控或细胞尸体清除导致的自我耐受性中断。了解人类SCARF1在凋亡细胞识别和清除过程中的作用，将为自身免疫的调节提供新的见解，并可能导致SLE患者开发新的和改进的治疗方法。

DESCRIPTION (provided by applicant): Efficient detection and clearance of apoptotic cells is essential in the maintenance of tolerance and tissue homeostasis. We recently identified the scavenger receptor expressed on endothelial cells-1 (SCARF1) as the receptor for apoptotic cells on dendritic cells via interactions with C1q/phosphatidylserine complexes on the dead cells (Ramirez-Ortiz et.al.; Nature Immunology). Loss of SCARF1 results in impaired uptake of apoptotic cells in vitro and in vivo, with accumulation of cell corpses in tissues and blood. Consequently, SCARF1 deficient mice develop lupus-like autoimmune disease. In this application, we propose to investigate the role of human SCARF1 in the onset and development of SLE. This is the next logical step in understanding the role of SCARF1 in apoptotic cell clearance, maintenance of tolerance and prevention of autoimmunity. We propose to: 1) Determine whether SCARF1 expression is dysregulated in SLE patients resulting in defects in apoptotic cell recognition and clearance by qRT-PCR, flow cytometry and ImageStream; 2) Define the interactions between SCARF1 with apoptotic cells via biochemical and imaging techniques; 3) Characterize the contribution of SCARF1 activation by C1q and/or apoptotic cells in dendritic cell signaling, maturation and antigen presentation using techniques such as T cell proliferation assay, Luminex analysis of cytokine secretion and confocal imaging techniques. Our preliminary data using cells from healthy volunteers shows that SCARF1 is highly expressed on monocytes and dendritic cells. We anticipate that SCARF1 expression will be downregulated on immune cells of SLE patients, exacerbating and/or accounting for the increased numbers of circulating apoptotic cells found in these patients. The etiology of SLE is unclear, but it is known that development of the disease results from a break in self-tolerance due to deregulated apoptosis or removal of cell corpses. Understanding the role of human SCARF1 in the processes of apoptotic cell recognition and clearance will provide new insight into the regulation of autoimmunity and could lead to the development of new and improved treatment for patients suffering from SLE.