AB0119 MECHANISM OF NEUTROPHIL EXTRACELLULAR TRAP IN PROMOTING SYNOVIAL HYPERPLASIA IN RHEUMATOID ARTHRITIS
Authors: Zhang Hui, Feng Yuchen, Kang Guorong, Liu Jinwu, Shen HaiLi
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Background:</h3> Rheumatoid arthritis(RA)is an autoimmune disease characterized by chronic inflammation of the synovial membrane and pannus formation.With the discovery of Neutrophil extracellular traps (NETs) in 2004, its role in autoimmune diseases has received much attention <sup>[1]</sup>.At present,studies on the pathogenesis of NETs in RA have focused on NETs as a source of citrullinated antigens <sup>[2]</sup>, producing autoantibodies to citrullinated protein antigens (ACPAs) <sup>[3]</sup>. In addition, NETs can activate rheumatoid arthritis fibroblast-like synoviocytes (RA-FLSs) to produce inflammatory cytokines <sup>[2]</sup>.Studies have reported that connective tissue growth factor (CTGF) is overexpressed in RA serum <sup>[4]</sup>, and CTGF plays a key role in the proliferation of RA-FLSs, furthermore leads to joint destruction in RA patients <sup>[5]</sup>. Therefore, our study stimulated RA-FLSs with NETs to detect cell proliferation and CTGF mRNA, aiming to explore the pathogenesis of NETs involved in RA. <h3>Objectives:</h3> To Explore the potential effects of Neutrophil extracellular traps (NETs) on rheumatoid arthritis synovial fibroblasts (RA-FLSs). <h3>Methods:</h3> The synovial tissues of RA patients were isolated and cultured in vitro; peripheral blood neutrophils were extracted from healthy volunteers and stimulated to formation NETs, NETs were extracted as a stimulating agent; MTS proliferation assay was used to evaluate the effect of NETs on the proliferation of RA-FLSs; qRT-PCR was used to determine the expression of connective tissue growth factor (CTGF) mRNA in cells treated with NETs-stimulated RA-FLSs for 60h. <h3>Results:</h3> The isolated and purified neutrophils could form NETs by stimulated in vitro. The concentration of extracted NETs -DNA was 58.5ng/ul (1×10<sup>6</sup> cells). Compared with the control group, NETs could promote the proliferation of RA-FLSs. With the increase of NETs concentration, the proliferation of RA-FLSs was also enhanced(F=99.519,P&lt;0.05);NETs stimulated the up-regulation of CTGF mRNA expression in RA-FLSs(30.696 ± 0.468 vs. 1, p&lt;0.01) <h3>Conclusion:</h3> NETs can promote the proliferation of RA-FLSs and stimulate the up-regulation of CTGF mRNA in RA-FLSs in vitro. <h3>References</h3> [1] April Barnado, Leslie J. Crofford, Jim C. Oates. At the Bedside: Neutrophil extracellular traps(NETs) as targets for biomarkers and therapies in autoimmune diseases. Journal of Leukocyte Biology Vol.99, No.2, pp:265-278, July, 2017. [2] Khandpur R, Carmona-Rivera C, Vivekanandan-Giri A, et al. NETs are a source of citrullinated autoantigens and stimulate inflammatory responses in rheumatoid arthritis. Sci Transl Med (2013) 5(178):178ra40. [3] Corsiero E, Bombardieri M, Carlotti E,Pitzalis C, et al. Single cell cloning and recombinant monoclonal antibodies generation from RA synovial B cells reveal frequent targeting of citrullinated histones of NETs.Ann Rheum Dis2016;75:1866–1875. [4] Nozawa K, Fujishiro M, Kawasaki M, et al. Connective tissue growth factor promotes articular damage by increased osteoclastogenesis in patients with rheumatoid arthritis. Arthritis Res Ther. 2009;11(6):R174. [5] S Ding, H Duan, F Fang, et al.CTGF promotes articular damage by increased proliferation of fibroblast-like synoviocytes in rheumatoid arthritis. Scand J Rheumatol 2016;45:4,282–287. <h3>Disclosure of Interests:</h3> None declared