Fee Laura T, Gogoi Debananda, O'Brien Michael E, McHugh Emer, Casey Michelle, Gough Ciara, Murphy Mark, Hopkins Ann M, Carroll Tomás P, McElvaney Noel G, Reeves Emer P
Alpha-1 Foundation Ireland, Royal College of Surgeons in Ireland, Beaumont Hospital, D02 YN77 Dublin, Ireland.
Irish Centre for Genetic Lung Disease, Department of Medicine, Royal College of Surgeons in Ireland, Beaumont Hospital, D02 YN77 Dublin, Ireland.
Biomedicines. 2021 Dec 16;9(12):1925. doi: 10.3390/biomedicines9121925.
Alpha-1 antitrypsin (AAT) deficiency (AATD) is characterized by increased risk for emphysema, chronic obstructive pulmonary disease (COPD), vasculitis, and wound-healing impairment. Neutrophils play a central role in the pathogenesis of AATD. Dysregulated complement activation in AATD results in increased plasma levels of C3d. The current study investigated the impact of C3d on circulating neutrophils. Blood was collected from AATD ( = 88) or non-AATD COPD patients ( = 10) and healthy controls (HC) ( = 40). Neutrophils were challenged with C3d, and degranulation was assessed by Western blotting, ELISA, or fluorescence resonance energy transfer (FRET) substrate assays. Ex vivo, C3d levels were increased in plasma ( < 0.0001) and on neutrophil plasma membranes ( = 0.038) in AATD compared to HC. C3d binding to CR3 receptors triggered primary ( = 0.01), secondary ( = 0.004), and tertiary ( = 0.018) granule release and increased CXCL8 secretion ( = 0.02). Ex vivo plasma levels of bactericidal-permeability-increasing-protein ( = 0.02), myeloperoxidase ( < 0.0001), and lactoferrin ( < 0.0001) were significantly increased in AATD patients. In endothelial cell scratch wound assays, C3d significantly decreased cell migration ( < 0.0001), an effect potentiated by neutrophil degranulated proteins ( < 0.0001). In summary, AATD patients had increased C3d in plasma and on neutrophil membranes and, together with neutrophil-released granule enzymes, reduced endothelial cell migration and wound healing, with potential implications for AATD-related vasculitis.
α1抗胰蛋白酶（AAT）缺乏症（AATD）的特征是患肺气肿、慢性阻塞性肺疾病（COPD）、血管炎和伤口愈合受损的风险增加。中性粒细胞在AATD的发病机制中起核心作用。AATD中补体激活失调导致血浆C3d水平升高。本研究调查了C3d对循环中性粒细胞的影响。从AATD患者（n = 88）、非AATD的COPD患者（n = 10）和健康对照者（HC）（n = 40）采集血液。用C3d刺激中性粒细胞，并通过蛋白质免疫印迹法、酶联免疫吸附测定（ELISA）或荧光共振能量转移（FRET）底物测定法评估脱颗粒情况。在体外，与HC相比，AATD患者血浆中C3d水平升高（P < 0.0001），中性粒细胞质膜上的C3d水平也升高（P = 0.038）。C3d与CR3受体结合触发初级颗粒（P = 0.01）、次级颗粒（P = 0.004）和三级颗粒释放（P = 0.018），并增加CXCL8分泌（P = 0.02）。AATD患者体外血浆中杀菌通透性增加蛋白水平（P = 0.02）、髓过氧化物酶水平（P < 0.0001）和乳铁蛋白水平（P < 0.0001）显著升高。在内皮细胞划痕试验中，C3d显著降低细胞迁移（P < 0.0001），中性粒细胞脱颗粒蛋白可增强这一效应（P < 0.0001）。总之，AATD患者血浆和中性粒细胞膜上的C3d增加，并且与中性粒细胞释放的颗粒酶一起，降低了内皮细胞迁移和伤口愈合能力，这可能与AATD相关的血管炎有关。
