Urinary sediment ICAM-1 level in lupus nephritis

Background: Urinary intercellular adhesion molecule-1 (ICAM-1) level is potentially a valuable biomarker of lupus nephritis (LN), but because ICAM-1 is a cell-surface molecule, soluble ICAM-1 level in urinary supernatant measured by ELISA may not be biologically relevant. Methods: The ICAM-1 level in urine sediment of 12 LN patients, 10 patients with pauci-immune necrotizing glomerulonephritis (NecGN), and six healthy controls were determined with a polymerase chain reaction (PCR)-based assay. The urinary sediment levels of miR-221, miR-222, miR-339-3P and miR-339-5P, which are involved in the regulation of ICAM-1 production, were also quantified. Results: LN patients had lower urinary sediment ICAM-1 levels than the other two groups (overall p = 0.034). In addition, urinary sediment ICAM-1 level inversely correlated with the estimated glomerular filtration rate (GFR) (r = -0.474, p = 0.026) but not other markers of lupus activity, or urinary sediment levels of miR-221, miR-222, miR-339-3P, or miR-339-5P. However, serum anti-dsDNA level inversely correlated with urinary sediment levels of miR-221 (r = -0.591, p = 0.043) and miR-222 (r = -0.689, p = 0.013), while urinary sediment miR-221 level also correlated with serum C3 level (r = 0.658, p = 0.02). Conclusions: We conclude that urinary sediment ICAM-1 level was significantly reduced in LN, and the level inversely correlated with renal function. Urinary sediment miR-221 and miR-222 levels correlate with lupus disease activity and may serve as biomarkers of LN. Lupus (2012) 21, 1190-1195.