ROLE OF MAC-1/ICAM-1 INTERACTIONS IN VASCULITIS

白细胞激活和白细胞-内皮细胞相互作用在血管病变中的作用仍然知之甚少，也缺乏特征性。本实验室最近报道，ICAM-1缺陷的MRL/MPJ-Fas/LPR小鼠表现出血管病变形成减少和血管坏死。该项目将研究一种假设，即白细胞和动脉内皮细胞之间的ICAM-1/Mac-1相互作用介导了血管炎性病变中观察到的白细胞激活、动脉内皮细胞损伤和随后的动脉血管坏死。这一假设将使用Mac-1和ICAM-1突变小鼠进行验证，这些小鼠已经回交到MRL/MPJ-Fas/LPR背景中，这是一种自发发展脉管炎的品系。第一个特异性目的是比较Mac-1突变体和Mac-1野生型MRL/MPJ-Fas/LPR小鼠之间血管病变的形成。Mac-1的表达在血管炎发展的不同阶段的作用将通过病理分级研究来确定。第二个特定目标将确定Mac-1/ICAM-1相互作用在体外白细胞激活和内皮细胞损伤中的作用。用肠系膜动脉内皮细胞培养法检测Mac-1突变型和野生型中性粒细胞对ICAM-1突变型和野生型MRL/MPJ-Fas的中性粒细胞粘附率。在这个体外模型中，还将使用Mac-1突变体和野生型中性粒细胞来确定白细胞的激活和内皮细胞的细胞毒性。该项目的体内和体外相结合的方法将极大地促进我们对白细胞黏附和白细胞介导的血管坏死在血管炎中的作用的理解。

The role of leukocyte activation and leukocyte-endothelial cell interactions remains poorly understood and characterized in vasculitic pathologies. This laboratory has recently reported that ICAM-1 deficient MRL/MpJ-Fas/lpr mice demonstrate reduced vasculitic lesion formation and vessel necrosis. This project will investigate the hypothesis that ICAM-1/Mac-1 interactions between leukocytes and arterial endothelial cells mediate leukocyte activation, arterial endothelial cell damage, and subsequent arterial vessel necrosis observed in vasculitic lesions. The hypothesis will be examined using both Mac-1 and ICAM-1 mutant mice that have been backcrossed onto the MRL/MpJ-Fas/lpr background, a strain that spontaneously develops vasculitis. The first specific aim is to compare vasculitic lesion formation between Mac-1 mutant and Mac-1 wild type MRL/MpJ-Fas/lpr mice. The role of Mac-1 expression will be determined during various stages of vasculitis development using pathological grading studies. The second specific aim will determine the role of Mac-1/ICAM-1 interactions in leukocyte activation and endothelial cell damage in vitro. Mesenteric arterial endothelial cell cultures will be used to measure neutrophil adhesion of Mac-1- mutant and wild type neutrophils to both ICAM-1 mutant and wild type MRL/MpJ-Fas measure neutrophil adhesion of Mac-1 mutant and wild neutrophils to both ICAM-1 mutant and wild type MRL/MpJ-Fas lpr endothelial cells. Leukocyte activation and endothelial cell cytotoxicity will also be determined using Mac-1 mutant and wild type neutrophils with this in vitro model. The combined in vivo and in vitro approach of this project will significantly advance our understanding of the role of leukocyte adhesion and leukocyte mediated vessel necrosis in vasculitis.