Increased urinary excretion of interleukin-17 in nephrotic patients

BACKGROUND/AIM: Interleukin (IL)-17 is a newly discovered cytokine that is secreted by activated memory CD4+ T cells and modulated the early stage of immune response. To elucidate the pathophysiology of minimal-change nephrotic syndrome (MCNS), we focused on IL-17, which is one of the key factors in regulating an inflammatory response, and thus determined the daily excretion of IL-17 in urine. METHODS: For this purpose, excretion levels of IL-17 were measured in the urine of patients with MCNS during relapse and remission using a highly sensitive sandwich enzyme-linked immunosorbent assay. The data obtained were compared with levels of daily urinary excretion of IL-17 in patients with IgA nephropathy (IgAN). A group of healthy subjects served as control. In both experimental groups urine levels of IL-17 excretion were plotted against their daily urinary protein excretion. RESULTS: We demonstrated increased levels of IL-17 excretion in the urine of patients with MCNS and IgAN as compared to the non-nephrotic and healthy controls. In MCNS the daily urinary IL-17 (uIL-17) excretion was increased and returned to baseline with remission of the nephrotic syndrome (NS). We also demonstrated a positive correlation between urinary protein excretion and daily uIL-17 excretion. CONCLUSION: Taken together, these data indicate that uIL-17 excretion is increased during the NS, suggesting the possibility that daily uIL-17 excretion may reflect the disease activity of NS.