MicroRNAs circulating in body fluid have been suggested as biomarkers of various diseases. We studied the serum and urinary level of several miRNA species (miR-200 family, miR-205 and miR-192) in patients with systemic lupus erythematosus (SLE). We studied 40 SLE patients. Serum and urinary miRNA levels were determined and compared with that of healthy controls. The serum levels of miR-200a, miR-200b, miR-200c, miR-429, miR-205 and miR-192, and urinary miR-200a, miR-200c, miR-141, miR-429 and miR-192 of SLE patients were lower than those of controls. Glomerular filtration rate (GFR) correlated with serum miR-200b (r = 0.411, p = 0.008), miR-200c (r  = 0.343, p  = 0.030), miR-429 (r  = 0.347, p = 0.028), miR-205 (r = 0.429, p = 0.006) and miR-192 (r =  0.479, p =  0.002); proteinuria inversely correlated with serum miR-200a (r = -0.375, p = 0.017) and miR-200c (r  = -0.347, p = 0.029). SLE disease activity index (SLEDAI) inversely correlated with serum miR-200a (r = -0.376, p = 0.017). Serum miR-200b (r =  0.455, p = 0.003) and miR-192 (r = 0.589, p < 0.001) correlated with platelet count, while serum miR-205 correlated with red cell count (r = 0.432, p =  0.005) and hematocrit (r = 0.370, p = 0.019). These pilot results suggested that miRNA may take part in the pathogenesis of SLE. Further studies are needed to validate the role of serum miRNA as a biomarker of SLE.

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.