Urine Monocyte Chemoattractant Protein-1 and Lupus Nephritis Disease Activity: Preliminary Report of a Prospective Longitudinal Study

Abstract

Objective. This longitudinal study aimed to determine the urine monocyte chemoattractant protein-1 (uMCP-1) levels in patients with biopsy-proven lupus nephritis (LN) at various stages of renal disease activity and to compare them to current standard markers. Methods. Patients with LN-active or inactive-had their uMCP-1 levels and standard disease activity markers measured at baseline and 2 and 4 months. Urinary parameters, renal function test, serological markers, and renal SLE disease activity index-2K (renal SLEDAI-2K) were analyzed to determine their associations with uMCP-1. Results. A hundred patients completed the study. At each visit, uMCP-1 levels (pg/mg creatinine) were significantly higher in the active group especially with relapses and were significantly associated with proteinuria and renal SLEDAI-2K. Receiver operating characteristic (ROC) curves showed that uMCP-1 was a potential biomarker for LN. Whereas multiple logistic regression analysis showed that only proteinuria and serum albumin and not uMCP-1 were independent predictors of LN activity. Conclusion. uMCP-1 was increased in active LN. Although uMCP-1 was not an independent predictor for LN activity, it could serve as an adjunctive marker when the clinical diagnosis of LN especially early relapse remains uncertain. Larger and longer studies are indicated.

Figure 1

Median uMCP-1 levels in LN relapse compared to pre- and postrelapse levels.

Figure 2

Receiver operating characteristic curve (ROC) of uMCP-1 compared with those of urinary parameters and SLEDAI-2K (renal) for the diagnosis of LN activity at 4 months. The black solid curve represents the uMCP-1; the area under the curve (AUC) was 0.87 (p < 0.001). The AUC for proteinuria was 0.89 (p < 0.001) and those for haematuria and leukocyturia were 0.62 (p = 0.07) and 0.62 (p = 0.08), respectively. The AUC for SLEDAI-2K was 0.85 (p < 0.001). Thus, uMCP-1 was better than haematuria and leukocyturia and essentially similar to proteinuria (uPCI) and SLEDAI-2K renal score for detection of LN activity at 4 months.