Abstract

Introduction: The Notch signalling pathway is activated in a wide variety of human renal diseases. We have recently demonstrated that the activation of this pathway is not involved in experimental renal fibrosis induced by angiotensin II or hypertension. Objectives: To assess whether the Notch pathway is activated in renal fibrosis related to hypertensive nephrosclerosis. To test the hypothesis, various glomerular diseases characterised by tubulointerstitial fibrosis were analysed. Method: Renal biopsies were performed on patients with hypertensive nephrosclerosis, in comparison with diabetic nephropathy and membranous nephropathy at various stages. Gene and protein expression were evaluated by in-situ hybridisation and immunohistochemistry respectively. Results: In hypertensive nephrosclerosis low renal expression of Notch-related proteins was observed. There was no link between tubulointerstitial fibrosis and the levels of these proteins. By contrast, in the glomerular diseases studied we observed high expression of the transcripts Jagged-1, HES-1 and TGF-beta and the proteins Jagged-1 gamma Notch-1, localised primarily in tubuloepithelial cells. The levels of expression of the components of the Notch pathway correlate to the degree of tubulointerstitial fibrosis, which confirms the activation of this pathway in progressive nephropathies. Conclusions: Our data demonstrate that the Notch pathway is not activated in the kidneys of patients with hypertensive nephropathy, which extends the results of experimental models of kidney damage related to hypertension to the realm of human pathology. Our studies provide new information on the complex regulation of the Notch pathway in the kidney.