McCarthy Cormac, Saldova Radka, O'Brien M Emmet, Bergin David A, Carroll Tomás P, Keenan Joanne, Meleady Paula, Henry Michael, Clynes Martin, Rudd Pauline M, Reeves Emer P, McElvaney Noel G
Respiratory Research Division, Royal College of Surgeons in Ireland , Beaumont Hospital, Dublin 9, Ireland.
J Proteome Res. 2014 Feb 7;13(2):596-605. doi: 10.1021/pr400752t. Epub 2013 Dec 13.
Alpha-1 antitrypsin (AAT) is the major physiological inhibitor of a range of serine proteases, and in the lung, it maintains a protease-antiprotease balance. AAT deficiency (AATD) is an autosomal co-dominant condition with the Z mutation being the most common cause. Individuals homozygous for Z (PiZZ) have low levels of circulating mutant Z-AAT protein leading to premature emphysematous lung disease. Extensive glycoanalysis has been performed on normal AAT (M-AAT) from healthy individuals and the importance of glycosylation in affecting the immune modulatory roles of AAT is documented. However, no glycoanalysis has been carried out on Z-AAT from deficient individuals to date. In this study, we investigate whether the glycans present on Z-AAT differ to those found on M-AAT from healthy controls. Plasma AAT was purified from 10 individuals: 5 AATD donors with the PiZZ phenotype and 5 PiMM healthy controls. Glycoanalysis was performed employing N-glycan release, exoglycosidase digestion and UPLC analysis. No difference in branched glycans was identified between AATD and healthy controls. However, a significant increase in both outer arm (α1-3) (p = 0.04) and core (α1-6) fucosylated glycans (p < 0.0001) was found on Z-AAT compared to M-AAT. This study has identified increased fucosylation on N-glycans of Z-AAT indicative of ongoing inflammation in AATD individuals with implications for early therapeutic intervention.
α1抗胰蛋白酶（AAT）是一系列丝氨酸蛋白酶的主要生理抑制剂，在肺部，它维持着蛋白酶-抗蛋白酶平衡。AAT缺乏症（AATD）是一种常染色体共显性疾病，其中Z突变是最常见的病因。Z型纯合个体（PiZZ）循环中的突变Z-AAT蛋白水平较低，会导致早发性肺气肿性肺病。已对健康个体的正常AAT（M-AAT）进行了广泛的糖基分析，并且记录了糖基化在影响AAT免疫调节作用方面的重要性。然而，迄今为止尚未对缺乏症个体的Z-AAT进行糖基分析。在本研究中，我们调查了Z-AAT上存在的聚糖是否与健康对照的M-AAT上的聚糖不同。从10名个体中纯化血浆AAT：5名具有PiZZ表型的AATD供体和5名PiMM健康对照。采用N-聚糖释放、外切糖苷酶消化和超高效液相色谱分析进行糖基分析。在AATD和健康对照之间未发现分支聚糖有差异。然而，与M-AAT相比，在Z-AAT上发现外臂（α1-3）（p = 0.04）和核心（α-1,6）岩藻糖基化聚糖均显著增加（p < 0.0001）。本研究已确定Z-AAT的N-聚糖上岩藻糖基化增加，这表明AATD个体存在持续炎症，对早期治疗干预具有重要意义。
