Expression of Transforming Growth Factor-beta1 in Cyclosporine-Induced Nephropathy in Rats

ABSTRACT

Cyclosporine nephropathy was induced by intraperitoneal injection of cyclosporine 25 mg/kg in Sprague-Dawley rats daily for 1, 4, 8, and 12 weeks to clarify the relationship between cyclosporine nephropathy and the expression of TGF-beta1 with extracellular matrix deposition. On light microscopic examination, the kidneys in the 12 week cyclosporine-treated rats showed focal or striped fibrosis, vacuolization of tubular cells, and injury of endothelial cells. Immunohistochemically, TGF-beta1 protein was strongly expressed in the cyclosporine-treated rat kidneys, especially in the glomerular endothelial cells, interstitial endothelial cells, tubular epithelial cells, and parietal cells in the Bowman's capsule of the glomerulus as well as the periglomerular arterioles. The amount of TGF-beta1 expression was correlated with the morphological change in the cyclosporine-treated rats. Extracellular matrix, such as fibronectin and collagen IV, was also expressed in the endothelial cells of the glomerulus and the interstitium. It can be concluded, therefore that TGF-beta1 protein is probably involved in the early stage of fibrogenesis in cyclosporine nephropathy. It can be postulated that cyclosporine nephropathy results from the accumulation of extracellular matrix associated with the increase of TGF-beta1 transcription. Therefore, these results could be used in reducing fibrosis in cyclosporine nephropathy.