Peptidylarginine deiminase 4 probably play an important role in rheumatoid arthritis by involving in the formation of the neutrophil extracellular traps

Abstract

Objective To detect the levels of peptidylarginine deiminase 4 (PAD4) mRNA and neutrophil extracellular traps (NETs) of the peripheral blood neutrophils in rheumatoid arthritis (RA) patients and to study the association between PAD4 and NETs in RA. The anti-cyclic citrullinated peptide (anti CCP) antibodies, disease activity score (DAS28) score, erythrocyte sedimentation rate (ESR) were recorded. Its value in the pathogenesis of RA was explored. T test, rank-sum test, Pearson and Spearman correlative analysis were used for statical analysis. Methods The serum double-stranded DNA (dsDNA)/NETs in 43 RA patients and 20 healthy controls were detected by PicoGreen dsDNA Quantitation Kits (Invitrogen). Real-time quantitative polymerase chain reaction (RT-PCR) was used to determine the expression of PAD4 mRNA in neutrophils, and the relationship between dsDNA/NETs and their clinical indexes were analyzed. Results ① The level of peripheral blood neutrophils PAD4 mRNA in RA was significantly higher than healthy controls [1.493(0.831, 2.607)] vs [0.631(0.358, 1.489)], (Z=-2.07, P=0.039). The levels of serum PAD4 mRNA in RA treated with disease-modifying antirheumatic drugs (DMARDs) were lower than untreated with DMARDs but no significant difference was found (Z =-1.19, P =0.234).② The levels of serum dsDNA/NETs in RA patients were significantly higher than in healthy controls (t=3.4, P=0.001).③ The levels of serum dsDNA/NETs in RA were positively correlated with DAS28 score, ESR, CRP and PAD4 mRNA (r=0.36, P=0.036; r=0.345, P=0.042; r=0.36, P=0.043; r=0.42, P=0.017) but not with anti-CCP antibodies (r=0.277, P=0.154). Conclusion ①PAD4 may play an important role in the pathogenesis of RA.② NETs maybe associated with disease activity and play an important role in RA pathogenesis, inhibit NETs generation or improve the ability to clear NETs, perhaps can treat RA. ③ PAD4 probably play an important role in rheumatoid arthritis by influencing the formation of the NETs. Key words: Arthritis, rheumatoid; Peptidylarginine deiminase 4; Neutrophil extracellular traps