P21 Discovery of potential urinary biomarkers from Korean patients with systemic lupus erythematosus

Objective This study aimed to demonstrate the potential of Activated Leukocyte Cell Adhesion Molecule (ALCAM), Hemopexin, and Peroxiredoxin (PRDX) 6 as urine biomarkers for systemic lupus erythematosus (SLE). Methods We collected urine samples from 138 patients with SLE from Ajou Lupus Cohort and 39 healthy controls (HC). The concentrations of urine biomarker levels were analyzed by enzyme-linked immunosorbent assay kits specific for ALCAM, hemopexin and PRDX 6, respectively, according to the manufacturer's protocols. Receiver operating characteristic (ROC) curve analysis was performed to evaluate diagnostic utility and Pearson's correlation analysis was conducted to assess the relationships among the disease activity and urine biomarkers. Results Patients with SLE showed a 5.7-fold increase in urinary ALCAM levels compared to HCs (6,760.5 pg/ml vs. 1,192.6 pg/ml, p < 0.001). In urinary hemopexin and PRDX6, the average levels were also significantly higher in patients with SLE compared to HCs (hemopexin, 649.8 ng/ml vs. 202 ng/ml, p < 0.001; PRDX6, 0.78 ng/ml vs. 0.17 ng/ml, p = 0.003). ALCAM, hemopexin, and PRDX6 showed more significant diagnostic value, especially for lupus nephritis (LN), and the area under the receiver operating characteristic curve for LN was 0.850 for ALCAM (95% CI, 0.778–0.921), 0.781 for hemopexin (95% CI, 0.695–0.867), and 0.714 PRDX6 (95% CI, 0.617–0.812). In correlation analysis, all were significantly associated with anti-double stranded DNA (ALCAM, r = 0.350, p < 0.001; hemopexin, r = 0.346, p < 0.001; PRDX6, r = 0.191, p = 0.026) and SLEDAI (ALCAM, r = 0.526, p < 0.001; hemopexin, r = 0.479, p < 0.001; PRDX6, r = 0.262, p = 0.002). Conclusions Urinary ALCAM, hemopexin and PRDX 6 were highly expressed patients with SLE compared to HCs. Thus, we suggest that urinary ALCAM, hemopexin and PRDX 6 can be potential biomarkers for SLE, especially valuable in the diagnosis of LN.