BMP-7 Protein Expression Is Downregulated in Human Diabetic Nephropathy

Bone morphogenetic protein-7 (BMP-7) is expressed in all parts of the normal kidney parenchyma, being highest in the epithelium of proximal tubules. It protects kidney against acute and chronic injury, inflammation and fibrosis. Diabetic nephropathy is the leading cause of chronic kidney disease, and is characterized by decreased expression of BMP-7. The aim of our study was to analyze whether the expression of BMP-7 is significantly changed in advanced stages of human diabetic nephropathy. Immunohistochemical analysis of the expression of BMP-7 was per¬formed on archival material of 30 patients that underwent renal biopsy and had confirmed diagnosis of diabetic nephropathy. Results showed that BMP-7 was differently expressed in the cytoplasm of epithelial cells of proximal tubules and podocytes among all stages of diabetic nephropathy. At early stages of diabetic nephropathy, BMP-7 was strongly positive in proximal tubules and podocytes, while low expression was recorded in the majority of samples at advanced stages. In conclusion, increased expression of BMP-7 at initial stages of diabetic nephropathy with subsequent decrease at advanced stage highlights the role of BMP-7 in the protection of kidney structure and function. Further investigations should be focused on disturbances of BMP-7 receptors and signaling pathways in patients with diabetic nephropathy.