[Expression and Clinical Significance of Semaphorin 3A in serum and mononuclear cells in patients with systemic lupus erythematosus].

Objective: To determine the expression of Sema3A in serum and peripheral blood mononuclear cells (PBMC) of patients with systemic lupus erythematosus (SLE), to analysis the correlation of Sema3A expression and SLE clinical manifestations and laboratory indexes, and to evaluate the diagnostic value of Sema3A in patients with SLE. Methods: The concentration of serum Sema3A was detected by enzyme-linked immuno sorbent assay (ELISA) in patients with SLE, healthy controls (HC) and diseases controls. In addition, the mRNA expression level of Sema3A was examined in PBMC by real-time polymerase chain reaction. The correlation of serum Sema3A level and clinical and laboratory features of SLE patients were analyzed. Unpaired t test, Kruskal-Wallis test, Mann-Whitney U test, χ(2) test, Pearson and Spearman correlation analysis were used to statistical analysis by using SPSS 13.0. Results: (1) Serum Sema3A concentration in patients with SLE was significantly lower than that in HC groups ( P <0.01). (2) Consistent with the serum level, the Sema3A mRNA level in SLE was lower than that in HC ( P =0.001). And the mRNA expression of Nrp-1 in SLE was also lower than that in HC ( P <0.01). (3) The serum Sema3A level in patients with SLE was positively correlated with haemoglobin (HGB) ( r =0.271, P <0.013), platelet (PLT) ( r =0.600, P <0.011), complement 3 (C3) ( r =0.234, P =0.0027) and complement 4 (C4) ( r =0.159, P =0.434) levels. Whereas, the expression of Sema3A was negatively correlated with SLE disease activity index (SLEDAI) ( r =-0.286, P =0.036). (4) Area under curve illustrated by ROC curve was 0.876 (95% CI: 0.846-0.906). The best cut-off value for the diagnosis of SLE was 6.31 μg/L, with the sensitivity of 80.6% and the specificity of 77.5%. The Youden index was 0.581. Above results indicated good validity of Sema3A as a diagnostic marker for SLE. (5) The HGB, PLT, C3 and C4 levels in the group of Sema3A- positiveSLE patients (≤6.31 μg/L) were lower than that in negative group (>6.31 μg/L), while CRP level and SLEDAI of positive group was higher than that in negative group( P <0.05). In addition, the positive rate of antinuclear antibodies ( P =0.046) and anticardiolipin antibody ( P =0.018) in the Sema3A-negative group were also significantly higher than that of negative group. Conclusions: Sema3A and Nrp-1 was both decreased in serum and PBMC of SLE patients, suggesting that the circulating expression of Sema3A and Nrp-1 was seriously defected in SLE. Circulating Sema3A was significantly correlated with disease activity and blood damage in patients with SLE. The result of ROC curve showed that Sema3A had the potential to be a new diagnostic biomarker in SLE.