Detection of osteopontin in sera, urine and renal tissue in patients with systemic lupus erythematosus and its significance.

Abstract

Objective To investigate the expression of osteopontin (OPN)in serum,urine and renal tissue of patients with systemic lupus erythematosus (SLE)and its relevance with organ damage in and activity of this disease.Methods Enzyme-linked immunoabsorbent assay(ELISA)was applied to detect the concentration of OPN in the sera of 100 patients with SLE and 30 sex-and age-matched normal human controls as well as in the urine of 57 patients with SLE and 15 normal human controls.Renal tissue was obtained from 3 patients with lupus nephritis and subjected to immunohistochemistry for the observation of OPN.Results The level of OPN was significantly higher in the sera and urine of patients with SLE than in those of normal human controls (64.03 ±72.87 μg/L vs 29.88±1 1.28μg/L,454.87±231.63 μg/L vs 122.67±39.47μg/L,both P<0.05).Increased level of OPN in sera and urine was also observed in patients with active SLE com-pared with those with inactive SLE (80.92±87.49μg/L vs 36.43±23.48μg/L,584.36±207.15 μs/L vs 28 1.08±1 3 1.92μg/L,both P<0.05).A positive correlation was noted between the serum level of OPN and SLE disease activity index(SLEDAI)(r=0.462,P<0.01),and the level of urine OPN was positively correlated with both SLEDAI and the concentration of urine immunoglobulin G.urine mierualbumin.urine α1-microglo-bulin,urine β2-microglobulin(r=0.901,0.458,0.359,0.342,0.409,respectively,all P<0.05).OPN was found in renal tubule epithelia of the three patients with lupus nephritis.Conclusion OPN may be involved in the pathogenesis of SLE and associated with the renal damage in patients with lupus nephritis. Key words: Lupus erythematosus,systemic; Osteopontin; Lupus nephritis