A case report suggesting the occurrence of epithelial-mesenchymal transition in obstructive nephropathy

Epithelial-mesenchymal transition (EMT) has been well investigated using cultured kidney epithelial cell lines and the mouse obstructive nephropathy model. The role of EMT in the genesis or progression of human renal fibrosis remains controversial. We report a case of obstructive nephropathy that occurred in a pregnant woman. Renal tissue obtained by percutaneous renal biopsy after the delivery showed marked interstitial fibrosis and obstructive tubuli. Immunofluorescence images clearly demonstrated S100A4-positive tubular epithelial cells in these specimens. With regard to human obstructive nephropathy, this is the first report which proves that tubular epithelial cells become positive for the fibroblast-specific marker. EMT is probably a common event not only in mouse but also in human.