Abstract
Our previous studies have shown that secreted extracellular matrix-associated protein Cysteine rich angiogenic inducer 61 (Cyr61), a novel proinflammatory factor, is involved in the pathogenesis of rheumatoid arthritis (RA). However, whether Cyr61 has any effect in systemic lupus erythematosus (SLE) remains unknown. This study aims to assess the level of serum Cyr61 and to investigate the association of serum Cyr61 and clinical disease activity in SLE. We found the level of serum Cyr61 in patients with SLE was significantly higher than healthy controls (P < 0.001), and Cyr61 was high expressed in renal tubule of lupus nephritis compared to control. The sensitivity of Cyr61 in diagnosis of SLE was 47.3%. In receiver operating characteristic (ROC) curve analysis, the area under the curve (AUC) was 0.830, with a 95% confidence interval (CI) from 0.776 to 0.885. Cyr61 was present in 60.0%, 54.5%, and 41.5% of anti-double stranded DNA (dsDNA), anti-antinuclear antibodies (ANA), and anti-Sm negative SLE patients, respectively. Serum Cyr61 levels were significantly higher in high systemic lupus erythematosus disease activity index (SLEDAI) group than that in low SLEDAI group (P = 0.003). Correlation analyzes showed a significant negative correlation between serum Cyr61 and complements (C3) (P = 0.015), C4 (P = 0.04). Moreover, increased Cyr61 level in SLE was associated with serum level of TNF-α, interleukin 6 (IL-6), and IL-17. In conclusion, serum Cyr61 was increased in patients with SLE which was associated with clinical disease activity and inflammation in SLE, suggesting Cyr61 may be a novel potential auxiliary marker for the diagnosis of SLE.