The role of urinary biomarker monocyte chemoattractant protein (MCP-1) in correlation with different histopathological classes of lupus nephritis in Egyptian patients.

Lupus nephritis (LN) affects almost two-thirds of systemic lupus erythematosus (SLE) patients. Renal biopsy is the gold standard for the diagnosis of LN. However, repeated biopsies are not always performed in clinical practice, and they carry some risk. Therefore, minimally invasive techniques, as urinary biomarkers, are promising tools for the diagnosis and monitoring of SLE. Previous studies evaluated urinary monocyte chemoattractant protein-1 (MCP-1) in patients with SLE, reported higher levels of urinary MCP-1 in patients with active LN than non-active LN. Other studies reported higher levels of urinary MCP-1 in LN patients with proliferative forms (III and IV). This study aimed to evaluate urinary MCP-1 as a noninvasive diagnostic biomarker tool for LN, and to determine its association with different LN histopathological stages and chronicity indices. The study included 40 SLE patients with biopsy-proven LN class II, III, IV or V, and 20 patients with inactive LN as a control group. In LN active patients, the mean creatinine was 1.71 ± 0.55 mg/dl, and 0.84 ± 0.10 mg/dl in the control group. The mean MCP-1 level was 618.4 ± 294.2 ng/l in active LN patients and 120.05 ± 87.53 ng/l in inactive LN patients. The receiver operating characteristic (ROC) curve analysis indicated a better diagnostic performance of MCP-1 than conventional biomarkers. At area under the curve of 0.990, the best cut-off level was >245 ng/L (sensitivity 97.5 %, Specificity 95 %). In conclusion, urinary MCP-1 distinguished active LN from inactive renal disease. It can be proposed as a good noninvasive diagnostic biomarker with a high sensitivity and specificity for detection of LN activity..