Expression of Glomerular-Smooth Muscle Actin and Vimentin in Idiopathic Membranous Nephropathy as Prognostic Indicators

ABSTRACT

BACKGROUND: The natural history of idiopathic membranous nephropathy (IMN) is heterogeneous with some patients showing spontaneous remission while others show a progressive course leading to end-stage renal failure. We tried to assess quantitatively alpha-smooth muscle actin (alpha-SMA) and vimentin expression as markers to predict the outcome of membranous nephropathy. METHODS: This study included 24 patients with biopsy proven IMN. We measured the volume of the positive area for alpha-SMA and vimentin within the glomeruli and compared the results with 5 patients in the normal control group. We evaluated glomerular alpha-SMA and vimentin expression in correlation with BUN and serum creatinine level at the time of diagnosis and after treatment. RESULTS: Glomerular alpha-SMA and vimentin in IMN were higher than in the control group. Glomerular alpha-SMA was significantly higher in progressive IMN than in non-progressive IMN. The glomerular alpha-SMA was sifnificantly correlated with BUN and serum creatinine at last follow-up (p<0.05), but there was no statistically significant correlation at diagnosis. The glomerular vimentin was not different between progressive and non-progressive groups. CONCLUSION: These data suggest that the expression of glomerular alpha-SMA may be a useful prognostic indicator and may be able to differentiate between patients with membranous nephropathy who respond well to treatment and those who continue to progress.