Urinary monocyte chemoattractant protein-1 correlates with disease activity in lupus nephritis

Monocyte chemoattractant protein-1 (MCP-1) has a pathogenic role in murine lupus nephritis (LN). We recruited 25 pediatric and adolescent systemic lupus erythematosus (SLE) patients from our lupus clinic [13 (52%) patients with LN and 12 (48%) lupus non-nephritis patients] and evaluated their urinary and plasma MCP-1 levels compared to adult and childhood controls. The median age and SLE disease duration of patients were 14.4 and 5.5 years, respectively. LN patients had a higher median renal (p=0.01) British Isles Lupus Assessment Group (BILAG) index, with a tendency for higher total BILAG scores (p=0.2). There were significantly increased urinary MCP-1 levels in the LN patients compared to healthy controls (p<0.001) whose values were significantly higher than lupus non-nephritis children (p<0.004). Urinary MCP-1 levels correlated well with total BILAG scores (r=0.82, p=0.04). There were no differences in plasma MCP-1 levels between SLE patient groups and pediatric controls, although the levels in the childhood controls were elevated compared to those of the adult controls (p<0.04). These results provide evidence of increased urinary--but not plasma--MCP-1 levels in children with LN, which correlates well with SLE disease activity as measured by the BILAG index.