Biomarkers of early kidney cells dysfunction in patients with membranous nephropathy

Abstract

Introduction/Objective. An unfavorable prognosis of membranous nephropathy (MN) is determined by the presence of persistent proteinuria and extensive tubulointerstitial lesions at initial biopsy. Our study investigated the value of markers of renal cell dysfunction (glomerular filtration rate, urinary excretion of protein, ectoenzyme proximal tubular epithelial cells, and oxidative stress) in patients with MN, and points to the use of these markers in a possible therapeutic modification. Methods. The study included 28 patients with MN and 30 healthy individuals as control. In addition to the basic laboratory studies, enzyme [aminopeptidase N (APN), plasma cell glycoprotein-1 (PC-1), N-acetyl- ?-D-glucosaminidase (NAGA), and dipeptidyl peptidase-4] activity was determined in serum and urine, as well as parameters of oxidative damage [thiobarbituric acid concentration of substance-responders (TBARS), malondialdehyde, and the concentration of the total sulfhydryl (SH) group]. Results. In patients with MN, serum activity of PC-1 and APN and urinary excretion of NAGA were significantly higher than in the control group. Also, significant correlation between daily proteinuria and serum PC-1 activity and urinary excretion of NAGA was found in patients with MN. Serum and urine levels of TBARS as well as total SH group levels were significantly lower in patients with MN than in healthy controls. Conclusion. Kidney damage in MN is accompanied by the release of several tubular enzymes, with potential diagnostic and prognostic significance. The study suggests a possible role of oxidative stress in pathogenesis of MN and the use of antioxidants in preventing impairment as part of future therapy.