Expression of receptors for advanced glycosylated end-products in renal disease.

Background: Advanced glycation endproducts (AGEs) are believed to mediate long-term complications in diabetes mellitus. In this context we studied the expression of the receptor for AGEs (RAGE) in the kidney of patients with a variety of different renal diseases.
Methods: RAGE was detected by immunocytochemistry in renal biopsies. We compared the staining for RAGE in nine patients with diabetic nephropathy, 20 with inflammatory and/or immune complex and 10 with non-inflammatory renal diseases. Normal renal tissue from seven patients with tumour nephrectomies served as controls.
Results: In controls the only cells expressing RAGE constitutively were interstitial cells and vascular smooth muscle cells (6/7), while distal tubular cells were rarely positive (1/7). Endothelial cells of arteries/arterioles, glomerular endothelial cells, podocytes, and capsular epithelial cells were consistently negative. In diabetic nephropathy, inflammatory and/or immune complex, and non-inflammatory renal diseases, all cell types mentioned above became positive for RAGE. Whilst the distribution of RAGE in the tissue was quite similar, staining intensity in inflammatory and/or immune complex diseases was higher than in diabetic nephropathy.
Conclusion: RAGE induction in the kidney is not specific for diabetic nephropathy and occurs in other types of renal diseases as well.