First Department of Internal Medicine, University Hospital of Alexandroupolis, Democritus University of Thrace, Alexandroupolis, Greece.
Laboratory of Molecular Hematology, University Hospital of Alexandroupolis, Democritus University of Thrace, Alexandroupolis, Greece.
Eur J Immunol. 2021 Apr;51(4):930-942. doi: 10.1002/eji.202048878. Epub 2021 Jan 22.
Ankylosing spondylitis (AS) is an inflammatory disease characterized by excessive bone formation. We investigated the presence of neutrophil extracellular traps (NETs) in AS and how they are involved in the osteogenic capacity of bone marrow mesenchymal stem cells (MSCs) through interleukin-17A (IL-17A). Peripheral neutrophils and sera were obtained from patients with active AS and healthy controls. NET formation and neutrophil/NET-associated proteins were studied using immunofluorescence, immunoblotting, qPCR, and ELISA. In vitro co-culture systems of AS NET structures and MSCs isolated from controls were deployed to examine the role of NETs in the differentiation of MSCs toward osteogenic cells. Analysis was performed using specific staining and qPCR. Neutrophils from patients with AS were characterized by enhanced formation of NETs carrying bioactive IL-17A and IL-1β. IL-17A-enriched AS NETs mediated the differentiation of MSCs toward bone-forming cells. The neutrophil expression of IL-17A was positively regulated by IL-1β. Blocking IL-1β signaling on neutrophils with anakinra or dismantling NETs using DNase-I disrupted osteogenesis driven by IL-17A-bearing NETs. These findings propose a novel role of neutrophils in AS-related inflammation, linking IL-17A-decorated NETs with the differentiation of MSCs toward bone-forming cells. Moreover, IL-1β triggers the expression of IL-17A on NETs offering an additional therapeutic target in AS.
强直性脊柱炎（AS）是一种炎症性疾病，其特征是过度的骨形成。我们通过白细胞介素-17A（IL-17A）研究了 AS 中中性粒细胞胞外诱捕网（NETs）的存在及其如何参与骨髓间充质干细胞（MSCs）的成骨能力。从活动期 AS 患者和健康对照者中获得外周中性粒细胞和血清。通过免疫荧光、免疫印迹、qPCR 和 ELISA 研究了 NET 形成和中性粒细胞/NET 相关蛋白。使用来自对照的 AS NET 结构和 MSC 的体外共培养系统来研究 NET 在 MSC 向成骨细胞分化中的作用。使用特异性染色和 qPCR 进行分析。AS 患者的中性粒细胞的特征是携带生物活性 IL-17A 和 IL-1β 的 NET 形成增强。富含 IL-17A 的 AS NET 介导 MSC 向成骨细胞分化。中性粒细胞中 IL-17A 的表达受 IL-1β 的正向调节。用 anakinra 阻断中性粒细胞上的 IL-1β 信号或用 DNase-I 破坏 NET 可破坏由携带 IL-17A 的 NET 驱动的成骨作用。这些发现提出了中性粒细胞在 AS 相关炎症中的新作用，将带有 IL-17A 的 NETs 与 MSC 向成骨细胞分化联系起来。此外，IL-1β 触发 NET 上 IL-17A 的表达，为 AS 提供了另一个治疗靶点。
