Increased expression of fibroblast growth factors in segmental renal dysplasia

Renal dysplasia (RD) is a disorganized development of renal parenchyma that results in a deficit of functional renal tissue. Dysplastic renal tissue i s characterized by primitive tubular epithelium associated with increased m esenchyme. Several polypeptide growth factors (GF), which interact with tar get cells through a cell-surface membrane receptor, have been reported to b e involved in the regulation of urothelial cell growth in normal and neopla stic states. Recent reports have demonstrated that basic fibroblast GF (bFG F, FGF-2) is a mitogen for renal proximal-tubule epithelial cells. Keratino cyte GF (KGF, FGF-7), which belongs to the FGF family, is believed to be a paracrine mediator of epithelial-cell proliferation. The aim of this study was to investigate the immunoactivity of bFGF and KGF and their receptors i n the dysplastic kidney in order to further understand the pathogenesis of RD. Specimens of dysplastic upper poles of duplex kidneys were surgically r esected from ten patients. Age-matched control material included six kidney specimens taken at autopsy from patients without evidence of urologic dise ase. Indirect immunohistochemistry was performed using the Stropt-ABC metho d with four antibodies: bFGF, KGF, FGF receptor (flg), and KGF receptor (be k). There was absent or weak bFGF, KGF, flg, and bek immunoreactivity in no rmal kidneys. In the dysplastic kidneys, there was strong immunoreactivity of bFGF and KGF and their receptors in the epithelium of primitive tubules. Increased local expression of bFGF and KGF and their receptors in primitiv e tubules suggests that bFGF and KGF may play an important role in the deve lopment of RD.