Correlation of contact system activation with occurrence of thrombotic events in patients with systemic lupus erythematosus

Abstract

Objective To explore the role of contact system activation in the mechanism of systemic lupus erythematosus (SLE) patients with thrombotic events. Methods A simple sample drawing study was conducted. Sixty-nine patients with SLE admitted to Department of Rheumatism in Tianjin Hospital from June 2014 to February 2016 were enrolled. The patients were divided into simple SLE group (n = 38) and SLE + vascular diseases (VD) group (n = 31) according to whether the patients complicated with VD or not. The VD patients were subdivided into three subgroups including SLE complicated with myocardial infarction (SLE + MI, n = 10), SLE complicated with deep vein thrombosis (SLE + DVT, n = 13), and SLE complicated with arterial thrombosis (SLE + AT, n = 8). Sixty-eight healthy age and gender-matched volunteers without history of VD were served as controls. Enzyme-linked immunosorbent assay (ELISA) was used to detect the content of FⅫa-C1 inhibitor (FⅫa-C1INH) and FⅫa-antithrombin (FⅫa-AT) in plasma. Flow cytometry was used to analyze the contents of platelets associated factors. The correlation between platelet associated factor and FⅫA-C1INH and FⅫa-AT was analyzed by Spearman correlation analysis. Receiver operating characteristic curve (ROC) was plotted to analyze the predictive value of FⅫA-C1INH and FⅫa-AT for SLE thrombotic events. Results Compared with health control group, the expression of FⅫa-C1INH in plasma in SLE group was significantly decreased [nmol/L: 0.00 (0.00, 0.07) vs. 0.08 (0.03, 0.13), P 0.40 nmol/L; predicted probability of two markers for predicting diagnosis was 0.5, the sensitivity and specificity were both 100%. Conclusions Contact system is activated in patients with SLE. FⅫA-C1INH and FⅫa-AT levels are closely related with platelet associated factors IFITM1 and PRKRA. FⅫA-C1INH and FⅫa-AT can be served as a promising potential biomarker for evaluation of the risk of thrombotic events in SLE. Key words: Systemic lupus erythematosus; Contact system; Thrombotic event