Abstract: Objective To investigate the relationship between serum neutrophil extracellular traps (NETs) and the prognosis of lupus nephritis (LN), and to analyze the prognostic value of NETs in LN. Methods There were 92 patients with LN (the LN group), 97 patients with systemic lupus erythematosus (SLE) and normal renal function (the SLE group), and 83 healthy volunteers (the control group) in this study. According to SLEDAI-2000 score, LN patients were divided into the mild activity group (score≤6, n=31), the moderate activity group (score7-12, n=33), the severe activity group (score＞12, n= 28). According to the occurrence of renal endpoint events during the follow-up period, LN patients were divided into the poor prognosis group (n=25) and the good prognosis group (n=67). Levels of serum NETs were detected to analyze the correlation between NETs and deoxyribonuclease 1 (DNASE1), renal function, SLEDAI-2000 score, renal tissue activity index (AI) and chronic index (CI) scores. Logistic regression was used to analyze the factors affecting the prognosis of LN, and receiver operating characteristic curve (ROC) was used to analyze the prognosis value of NETs in patients with LN. Results The serum level of NETs was higher in the LN group than that of the SLE group and the control group. The serum level of NETs was higher in the severe activity group than that of the moderate activity group and the mild activity group. The serum NETs level was higher in the moderate activity group than that of the mild activity group (P＜0.05). Levels of NETs were negatively correlated with glomerular filtration rate (eGFR) and DNASE1 (r=-0.769), and positively correlated with 24 h urinary protein quantification, SLEDAI-2000 score, renal tissue AI and CI (P＜0.05). High AI score and high NETs were risk factors for poor prognosis of LN (P＜0.05). The area under curve (AUC) of NETs for predicting prognosis in patients with LN was 0.871, with a sensitivity of 80.00% and a specificity of 86.57%. Conclusion Elevated levels of NETs are associated with degree of renal injury and renal end point events in LN, and can be used as a prognostic indicator for LN.

Key words: lupus nephritis, lupus erythematosus, systemic, extracellular traps, neutrophils, deoxyribonuclease Ⅰ,  renal insufficiency