Protein disulfide isomerase in neutrophil recruitment and vascular inflammation

描述（由申请人提供）：中性粒细胞在血管炎症和损伤的先天免疫反应中是必不可少的。中性粒细胞向血管损伤部位募集是一个多步骤的过程，包括中性粒细胞滚动、牢固粘附和迁移。选择素与其配体的相互作用介导中性粒细胞在炎症内皮上的滚动，并进一步调节整合素的功能。随后，活化的LFA-1和Mac-1在中性粒细胞粘附和跨内皮转运中起关键作用。然而，整合素在中性粒细胞募集过程中被激活的分子机制尚不清楚。有人提出，氧化还原敏感的硫-二硫交换可能对整合素的激活很重要。蛋白二硫异构酶（Protein disulfide isomerase， PDI）是一种细胞表面定位的硫醇异构酶，在b3整合素的硫醇交换中起重要作用，从而调节b3整合素介导的血小板和内皮细胞功能。我们的假设是，中性粒细胞表面PDI通过促进氧化还原敏感的硫醇交换来调节b2整合素的功能，将b2整合素转移到炎症期间b2整合素介导的中性粒细胞募集所需的活性构象。基于我们的初步数据有力地支持了这一假设，在Aim 1中，我们将定义细胞表面PDI在b2整合素与其对抗受体ICAM-1的相互作用以及b2整合素介导的中性粒细胞粘附和转运中的作用。在目标2中，我们将确定PDI与b2整合素相互作用以调节其功能的分子机制。在Aim 3中，我们将在体内使用实时荧光活体显微镜研究细胞表面PDI在炎症条件下b2整合素介导的中性粒细胞粘附和转运中的病理生理作用。更好地了解PDI如何调节b2整合素介导的中性粒细胞募集到炎症部位，可能会导致新的治疗方法的发展，以预防和治疗炎症和组织损伤。

DESCRIPTION (provided by applicant): Neutrophils are essential for the innate immune response during vascular inflammation and injury. Neutrophil recruitment into the site of vascular injury is a multi-step process consisting of neutrophil rolling, firm adhesion, and transmigration. Interaction of selectins with their ligands mediates neutrophil rolling over the inflamed endothelium and further regulates integrin function. Subsequently, activated LFA-1 and Mac-1 play critical roles in neutrophil adhesion to and transmigration across the endothelium. However, the molecular mechanism by which the integrins are activated during neutrophil recruitment remains unclear. It has been proposed that redox-sensitive thiol-disulfide exchange in integrins may be important for their activation. Protein disulfide isomerase (PDI), a cell surface localized thiol isomerase, plays an important role in thiol exchange in b3 integrins, thereby regulating b3 integrin-mediated platelet and endothelial cell function. It is our hypothesis that neutrophil surface PDI regulates b2 integrin function by facilitating redox-sensitive thiol exchange, shifting b2 integrin to its active conformation required for b2 integrin-mediated neutrophil recruitment during inflammation. Based on our preliminary data which strongly support the hypothesis, in Aim 1, we will define the role of cell surface PDI in the interaction of b2 integrin with its counter-receptor, ICAM-1 and in b2 integrin-mediated neutrophil adhesion and transmigration. In Aim 2, we will identify the molecular mechanisms by which PDI interacts with b2 integrins to regulate their function. In Aim 3, we will investigate the pathophysiological role of cell surface PDI in b2 integrin-mediated neutrophil adhesion and transmigration under inflammatory conditions using real-time fluorescence intravital microscopy in vivo. A better understanding of how surface PDI regulates b2 integrin-mediated neutrophil recruitment into the site of inflammation may lead to the development of novel therapeutics to prevent and treat inflammation and tissue injury.