Shida Haruki, Nakazawa Daigo, Tateyama Yu, Miyoshi Arina, Kusunoki Yoshihiro, Hattanda Fumihiko, Masuda Sakiko, Tomaru Utano, Kawakami Tamihiro, Atsumi Tatsuya, Ishizu Akihiro
Division of Rheumatology, Endocrinology and Nephrology, Hokkaido University Graduate School of Medicine , Sapporo , Japan.
Undergraduate School of Health Sciences, Hokkaido University , Sapporo , Japan.
Front Immunol. 2016 Dec 23;7:636. doi: 10.3389/fimmu.2016.00636. eCollection 2016.
Lactoferrin (Lf) is one of the antigens of antineutrophil cytoplasmic antibodies (ANCA) and functions as an endogenous suppressor of neutrophil extracellular trap (NET) formation. However, the prevalence and pathogenicity of anti-lactoferrin antibodies (aLf) in ANCA-associated vasculitis (AAV) remain unrevealed. This study aimed to examine the significance of aLf in AAV, initially. Sixty-five sera from AAV patients, including 41 microscopic polyangiitis, 5 granulomatosis with polyangiitis, and 19 eosinophilic granulomatosis with polyangiitis (EGPA) patients, were subjected to aLf detection using enzyme-linked immunosorbent assay. Clinical characteristics were compared between aLf-positive and aLf-negative patients. Neutrophils from healthy donors were exposed to suboptimal dose (10 nM) of phorbol myristate acetate (PMA) with aLf followed by evaluation of NET formation. Results demonstrated that 4 out of 65 AAV sera (6.2%) were positive for aLf. All of them were EGPA sera (4/19, 21.1%). In EGPA, the frequency of renal involvement, serum CRP levels, and Birmingham Vasculitis Activity Score (BVAS) in the aLf-positive patients was significantly higher than those in the aLf-negative patients, and the aLf titer correlated positively with the serum CRP level and BVAS. The NET formation was particularly enhanced by combined stimulation of 10 nM PMA and 1 µg/mL aLf. IgG isolated from sera of the aLf-positive EGPA patients (250 µg/mL) enhanced NET formation induced by 10 nM of PMA, and the effect was abolished completely by absorption of the aLf. This pilot study suggests that aLf enhance NET formation induced by PMA and are associated with disease activity of EGPA.
乳铁蛋白（Lf）是抗中性粒细胞胞浆抗体（ANCA）的抗原之一，作为中性粒细胞胞外诱捕网（NET）形成的内源性抑制剂发挥作用。然而，抗乳铁蛋白抗体（aLf）在ANCA相关性血管炎（AAV）中的患病率及致病性仍不明确。本研究旨在初步探讨aLf在AAV中的意义。使用酶联免疫吸附测定法对65例AAV患者的血清进行aLf检测，这些患者包括41例显微镜下多血管炎、5例肉芽肿性多血管炎和19例嗜酸性肉芽肿性多血管炎（EGPA）患者。比较了aLf阳性和aLf阴性患者的临床特征。将健康供者的中性粒细胞暴露于次优剂量（10 nM）的佛波酯肉豆蔻酸酯（PMA）和aLf中，随后评估NET的形成。结果显示，65例AAV血清中有4例（6.2%）aLf呈阳性。所有阳性血清均来自EGPA患者（4/19，21.1%）。在EGPA中，aLf阳性患者的肾脏受累频率、血清CRP水平和伯明翰血管炎活动评分（BVAS）显著高于aLf阴性患者，且aLf滴度与血清CRP水平和BVAS呈正相关。10 nM PMA和1 μg/mL aLf联合刺激可特别增强NET的形成。从aLf阳性EGPA患者血清中分离的IgG（250 μg/mL）增强了10 nM PMA诱导的NET形成，而aLf的吸附完全消除了这种作用。这项初步研究表明，aLf增强了PMA诱导的NET形成，并与EGPA的疾病活动相关。
