CD177 is a glycosylphosphatidylinositol (GPI)-anchored protein expressed by a variable proportion of human neutrophils that mediates surface expression of the antineutrophil cytoplasmic antibody antigen proteinase 3. CD177 associates with β2 integrins and recognizes platelet endothelial cell adhesion molecule 1 (PECAM-1), suggesting a role in neutrophil migration. However, CD177^pos neutrophils exhibit no clear migratory advantage in vivo, despite interruption of in vitro transendothelial migration by CD177 ligation. We sought to understand this paradox. Using a PECAM-1-independent transwell system, we found that CD177^pos and CD177^neg neutrophils migrated comparably. CD177 ligation selectively impaired migration of CD177^pos neutrophils, an effect mediated through immobilization and cellular spreading on the transwell membrane. Correspondingly, CD177 ligation enhanced its interaction with β2 integrins, as revealed by fluorescence lifetime imaging microscopy, leading to integrin-mediated phosphorylation of Src and extracellular signal-regulated kinase (ERK). CD177-driven cell activation enhanced surface β2 integrin expression and affinity, impaired internalization of integrin attachments, and resulted in ERK-mediated attenuation of chemokine signaling. We conclude that CD177 signals in a β2 integrin-dependent manner to orchestrate a set of activation-mediated mechanisms that impair human neutrophil migration.

CD177是糖基磷脂酰肌醇（GPI）锚定的蛋白质，由可变比例的人类嗜中性粒细胞表达，介导抗嗜中性粒细胞胞浆抗体抗原蛋白酶3的表面表达。CD177与β2整合素结合并识别血小板内皮细胞粘附分子1（PECAM-1），提示在嗜中性粒细胞迁移中起作用。然而，尽管通过CD177的连接中断了体外跨内皮迁移，但CD177 ^pos中性粒细胞在体内没有明显的迁移优势。我们试图理解这种悖论。使用独立于PECAM-1的transwell系统，我们发现CD177 ^pos和CD177 ^neg嗜中性粒细胞可相对迁移。CD177连接选择性地损害CD177 ^pos的迁移嗜中性粒细胞，是通过在跨孔膜上固定和细胞扩散介导的效应。相应地，如荧光寿命成像显微镜所揭示的，CD177连接增强了其与β2整联蛋白的相互作用，导致整联蛋白介导的Src磷酸化和细胞外信号调节激酶（ERK）。CD177驱动的细胞活化增强了表面β2整合素的表达和亲和力，破坏了整合素附着的内在化，并导致ERK介导的趋化因子信号传导减弱。我们得出的结论是，CD177以β2整联蛋白依赖性方式发出信号，以协调一系列损害人类嗜中性粒细胞迁移的激活介导的机制。