Effects of Spironolactone on the Urinary Excretion of TGF-beta1 in IgA Nephropathy

Jeong, Kyung Hwan; Park, Mina; Moon, Joo Young; Lee, Sang Ho; Lee, Tae Won; Ihm, Chun Gyoo

Abstract

PURPOSE: Transforming growth factor-beta1 (TGF-beta1) has an important role in the pathogenesis of renal damage; it enhances extracellular matrix production. Urinary TGF-beta1 excretion has been shown to be significantly increased in patients with IgA nephropathy. The aim of the present study was to evaluate the effect of spironolactone on urinary TGF-beta1 levels in patients with IgA nephropathy.
METHODS
TGF-beta1 was measured by enzyme-linked immunosorbent assay in random urine specimens from 35 patients with IgA nephropathy. The patients were assigned to a spironolactone group, prednisolone group or losartan group. They were treated over an 8-week period. Urine samples were tested at the beginning and the end of the treatment period.
RESULTS
The patients with IgA nephropathy (n=35) had a higher urinary excretion of TGF-beta1 than normal controls (n=13). Urinary TGF-beta1 excretion was positively correlated with proteinuria and pathological grading but not with serum creatinine. After 8 weeks of treatment, losartan (n=13) and prednisolone (n=11) therapy induced a significant reduction in both urinary protein and TGF-beta1 excretion. After treatment with spironolactone (n=11), urinary protein and TGF-beta1 excretion were decreased. However, the decrease was not statistically significant. There was a significant correlation between the urinary TGF-beta1 excretion and the serum aldosterone (r=0.84; p<0.01); however, treatment with spironolactone abolished this correlation.
CONCLUSION
This study provides evidence that endogenous aldosterone influences urinary TGF-beta1 excretion in patients with IgA nephropathy.