Plasma-soluble urokinase-type plasminogen activator receptor levels are associated with clinical and pathological activities in lupus nephritis: a large cohort study from China

Background In this study, we detected plasma urokinase plasminogen activator (uPA) and soluble urokinase-type plasminogen activator receptor (uPAR) levels in Chinese lupus nephritis patients from a large cohort. The associations between plasma uPA and soluble uPAR and clinico-pathological characteristics were further analyzed. Methods The levels of plasma uPA and soluble uPAR were detected by ELISA in 202 patients with active lupus nephritis, 17 systemic lupus erythematosus (SLE) patients without renal involvement and 21 normal controls. Results There were no significant differences in the levels of the average plasma uPA among the lupus nephritis group, non-renal SLE group and normal control group (p=0.129). The plasma-soluble uPAR level in the lupus nephritis group was significantly higher than that in the non-renal involvement SLE group (p=0.004) and that in normal controls (p<0.001). The plasma uPAR levels were positively associated with SLEDAI scores (r=0.215, p=0.007). In renal pathological data, there was significant difference of plasma-soluble uPAR levels among various pathological classes, which was the highest in the class IV group (p=0.012). The level of plasma-soluble uPAR was found to be a risk factor for long-term renal outcomes in lupus nephritis by univariate survival analysis (p=0.013, HR=6.326, 95% CI: 1.466-27.298). Conclusions Our study showed that the significantly increased plasma levels of soluble uPAR could be found in active lupus nephritis, and they were associated with some clinico-pathological features. Its involvement in the pathogenesis of lupus nephritis warrants further study.