Department of Pathology and Medical Biology,
Department of Rheumatology and Clinical Immunology and.
Rheumatology (Oxford). 2016 Jan;55(1):162-72. doi: 10.1093/rheumatology/kev293. Epub 2015 Aug 28.
Granulomatosis with polyangiitis (GPA) is a relapsing small-vessel vasculitis characterized by circulating ANCA against PR3. The mechanisms that trigger PR3-ANCA production are unknown. The aim of this study was to determine whether endogenous factors [B cell activating factor (BAFF) and IL-21] and exogenous factors [oligodeoxynucleotides containing CpG motifs (CpG-ODN)] synergize in stimulating PR3-ANCA production in GPA patients.
Peripheral blood mononuclear cells from GPA patients and healthy controls (HCs) were cultured in the presence of BAFF and IL-21, with or without CpG-ODN, for 12 days. PR3-ANCA production in culture supernatants was quantified by Phadia EliA. Phenotypic characterization and the influence of CpG-ODN treatment on IL-21 receptor (IL-21R), transmembrane activator and calcium-modulator and cyclophilin ligand interactor (TACI) and BAFF receptor (BAFF-R) expression on B cells was analysed by flow cytometry.
Stimulation with BAFF and IL-21 significantly increased ANCA production in patient samples, which could be augmented further by addition of CpG-ODN. Stimulation with CpG-ODN increased the percentage of IL-21R(+) and TACI(+) B cells but did not affect BAFF-R expression. GPA patients had an increased percentage of circulating IL-21R(+) and a decreased percentage of TACI(+) circulating memory B cells when compared with HCs. Additionally, patients had decreased expression of BAFF-R on B cells, which was inversely correlated with BAFF concentrations in plasma.
Our data demonstrate that endogenous and exogenous factors can synergize to promote PR3-ANCA production. Mechanistically, CpG-ODN up-regulated IL-21R and TACI expression on B cells, possibly sensitizing these cells for IL-21- and BAFF-mediated signals. Agents inhibiting Toll-like receptor 9, BAFF and IL-21 signalling pathways may serve as potential therapeutics for intervention in GPA patients.
肉芽肿性多血管炎（GPA）是一种复发性小血管血管炎，其特征是循环抗蛋白酶 3 中性粒细胞胞浆抗体（PR3-ANCA）。触发 PR3-ANCA 产生的机制尚不清楚。本研究旨在确定内源性因子（B 细胞激活因子（BAFF）和白细胞介素 21（IL-21））和外源性因子（含 CpG 基序的寡脱氧核苷酸（CpG-ODN））是否在刺激 GPA 患者 PR3-ANCA 产生方面具有协同作用。
将 GPA 患者和健康对照者（HCs）的外周血单个核细胞在 BAFF 和 IL-21 的存在下培养 12 天，有或没有 CpG-ODN。通过 Phadia EliA 定量测定培养上清液中 PR3-ANCA 的产生。通过流式细胞术分析 CpG-ODN 处理对 B 细胞上白细胞介素 21 受体（IL-21R）、跨膜激活剂和钙调节剂和环胞素配体相互作用（TACI）和 B 细胞激活因子受体（BAFF-R）表达的影响。
BAFF 和 IL-21 的刺激显著增加了患者样本中的 ANCA 产生，而添加 CpG-ODN 则进一步增强了这种作用。CpG-ODN 的刺激增加了 IL-21R（+）和 TACI（+）B 细胞的百分比，但不影响 BAFF-R 的表达。与 HCs 相比，GPA 患者循环 IL-21R（+）的百分比增加，而循环记忆 B 细胞 TACI（+）的百分比降低。此外，患者 B 细胞上的 BAFF-R 表达降低，这与血浆中 BAFF 浓度呈负相关。
我们的数据表明，内源性和外源性因素可以协同促进 PR3-ANCA 的产生。从机制上讲，CpG-ODN 上调了 B 细胞上的 IL-21R 和 TACI 表达，可能使这些细胞对 IL-21 和 BAFF 介导的信号敏感。抑制 Toll 样受体 9、BAFF 和 IL-21 信号通路的药物可能作为 GPA 患者干预的潜在治疗药物。
