Steroid therapy and urinary transforming growth factor-beta 1 in IgA nephropathy

Transforming growth factor-beta1 (TGF-beta1) has an important role in the p athogenesis of glomerular damage by influencing matrix metabolism. An assoc iation of TGF-beta1 with glomerulosclerosis and interstitial fibrosis has b een shown in various renal diseases, suggesting that TGF-beta1 may serve as a diagnostic marker of glomerular diseases. The aim of this study is to de termine the usefulness of urinary TGF-beta1 values to monitor therapeutic e ffects of steroids in patients with immunoglobulin A (IgA) nephropathy. Con centrations and activation rates of TGF-beta1 (mature/total) were determine d in urine of patients with renal diseases by means of a double-antibody en zyme immunoassay. The urinary TGF-beta1 level before steroid therapy was co mpared with renal histological characteristics, creatinine clearance, and p roteinuria in patients with a variety of renal diseases. Urinary excretion of total and mature TGF-beta1 was significantly greater in patients with cr escentic glomerulonephritis and IgA nephropathy than in healthy controls, w hereas the activation rate of urinary TGF-beta1 was similar among patients with other renal diseases. Urinary TGF-beta1 excretion at the time of renal biopsy significantly correlated with the degree of crescent formation in p atients with IgA nephropathy, but not in those with glomerular sclerosis or tubulointerstitial fibrosis. Urinary excretion of total and mature TGF-bet a1 was reduced in patients with IgA nephropathy after treatment with predni solone (0.8 mg/kg/d) for 1 month. The activation rate of urinary TGF-beta1 also decreased significantly after steroid therapy. Urinary TGF-beta1 value s therefore may be useful to assess disease activity or the effects of ster oid therapy in patients with IgA nephropathy. (C) 2001 by the National Kidn ey Foundation, Inc.