Serum and urinary free microRNA level in patients with systemic lupus erythematosus

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.