Objective To investigate the mRNA and protein expression levels of telomeric-repeat binding factor-1 (TRF1) and TRF2 in the peripheral blood mononuclear cells (PBMCs) of patients with systemic lupus erythematosus (SLE),and the relations between these gene expression levels and clinical data of SLE patients were explored.Methods According to disease activity,these SLE patients were divided into the active group (40 cases) and the stable group (67 cases).These patients were also grouped as renal damage group (46 cases) and renal damage-free group (61 cases) based on their renal conditions.Healthy individuals (41 cases) were also included as control.Real-time quantitative polymerase chain reaction (RT-qPCR) was employed to study the mRNA expression of TRF1 and TRF2.The protein levels of TRF1 and TRF2 were measured by Western Blot (WB).Independent-Samples t test or one-way analysis of variance (ANOVA) in conjunction with the Least-Significant Difference method (LSD method) wasperformed if the data were in normal distributions;otherwise,the Kruskal-Wallis test was applied.Spearman's correlation analysis was also used for statistical analysis.Results The mRNA and protein expression levels of TRF1 and TRF2 in the PBMCs of the active group (TRF1:0.003 1±0.003 3;TRF2:0.010 5±0.064 8) and renal damage group (TRF1:0.002 3 ±0.002 6;TRF2:0.004 3 ±0.003 3) were significantly increased compared to the stable group (TRF1:0.001 2±0.001 1;TRF2:0.004 2±0.008 6),the renal damage-free group (TRF1:0.001 3±0.001 8;TRF2:0.003 4±0.007 2) and healthy (TRF1:0.001 2±0.003 0;TRF2:0.003 4±0.002 7) individuals respectively (P＜0.05).In SLE patients,the expression levels of TRF1 mRNA were correlated with erythrocyte sedimentation rate (r=0.365,P＜0.05);the expression levels of TRF2 mRNA were correlated with SLEDAI score (r=0.270,P＜0.05),erythrocyte sedimentation rate (r=0.304,P＜0.05),creatinine (r=0.258,P＜0.05) and 24-hour urinary protein (r=0.344,P＜0.05).Conclusion Altered expression of TRF1 and TRF2 might be involved in the pathogenesis of Systemic lupus erythematosus.The positive correlation between TRF2 and SLEDAI score,24-hour urinary protein suggest that TRF2 might be usedas a biomarker for disease activity or renal damage in