siRNA抑制PAD4介导的中性粒细胞胞外诱捕网（NETs）释放治疗RA的实验性研究

类风湿关节炎（RA）是以慢性进展性侵蚀性滑膜炎为病理改变的自身免疫性疾病，有较高致残率死亡率。抗瓜氨酸化抗体（ACPAs）是RA特异性抗体，在RA发病机制中有重要重用。其抗原产生来源尚未明确。研究发现形成假说：NETosis可以把胞内自身抗原瓜氨酸化修饰化并外化胞外，打破自身耐受，实现天然免疫向特异性自身免疫的跨越。前炎症细胞因子、ACPAs与NETosis相互促进，形成自循环环路，并与瓜氨酸化抗原/抗体自循环环路交错，通过不断二次打击机制，促进ACPAs表位扩展和亲和力成熟，疾病慢性化。本研究拟通过RNAi沉默PMN的PAD4，观察PAD4沉默后，NETosis活性是否受到抑制，PAD4沉默后PMN与PBMCs共孵育的上清液来刺激FLS培养，其增殖、凋亡、迁移、侵袭、炎症细胞因子表达是否有变化？为阐明NETs在RA发病机制中的作用提供依据，为以NETs为靶向的生物治疗技术开发奠定基础。

Rheumatoid arthritis(RA) is a chronic, progressive autoimmune disease characted as erosive synovitis, with high morbidity and mortality. anticitrullinated protein antibodies (ACPAs) are RA-specific antibodies with crucial role in the pathogenesis of RA. The origin of the autoantigen is still not clear. Neutrophil extracellular traps (NETs) were hypothesized to break the self-tolerance and excess the naive immunity to adaptive autoimmunity in RA by citrullination modification of intracellular autoantigens and externalization. Proinflammatory cytokines, ACPAs and NETosis promote each other to form a self-development loop, overlaping with that of citrullinated antigen /ACPs.By 2-hit mechanism，NETs promote epitope spreading of citrullinated autoantigens and affinity maturation of ACPAs, and maintain the chronicity of autoimmune responses in RA . This study is designed to assess the activity of NETosis in RA polymorphonuclear neutrophils (PMNs) after the gene silencing of peptidyl arginine deiminase IV with siRNA. To analyze whether the proliferation, apoptosis, migration, invasion of RA synovial fibroblast-like synoviocyte (FLS) and proinflammatory cytokines levers will be changed when RA FLS were cultured with the supernatant of PAD4 -silenced RA PMN , co-incubated with PBMCs. NETs may offer insight into the pathogenesis of RA and provide promise in developing novel biological therapeutic agents.