Immunohistochemical study of epidermal growth factor receptor (EGFR) in various types of renal injury

Epidermal growth factor (EGF), a polypeptide with a potent mitogen activity, and its receptor [EGFR] have been previously identified in the kidney, but their expression in normal and diseased kidneys has not been fully elucidated. In order to evaluate EGFR in various histological types of renal injury, EGFR expression was studied by the immunohistochemical avidin-biotin complex (ABC) method with a monoclonal antibody EGFR1 on paraffin sections from 10 normal kidneys, 56 renal biopsies with various types of glomerulonephritis (GN), and 20 renal grafts with rejection. EGFR expression was observed in (a) 3 of 10 (30%) normal kidneys, (b) 17 of 39 (43.6%) renal biopsies with various types of GN mainly in membranous GN (57%) and in focal segmental glomerulosclerosis (FSG) (62.5%), (c) 6 of 17 (35.3%) biopsies with various types of systemic lupus erythematosus GN, and (d) 12 of 20 (60%) renal grafts with acute (42.9%) and chronic (69.2%) rejection. EGFR was mainly localized to the epithelial cells of the distal and collecting tubules and extraglomelar vessels, while it was observed less frequently in parietal epithelial cells and along glomerular basement membranes. Notably EGFR was detected in the epithelial cells adjacent to adhesions with Bowman's capsule and in the connective tissue of fibrocellular crescents. In conclusion, EGFR expression was observed more frequently in diseased than in normal kidneys. The increased incidence of EGFR expression in FSG, in chronic rejection, in small adhesions with Bowman's capsule and fibrocellular crescents suggest that EGF/EGFR may be correlated with a disturbed extracellular matrix production resulting in formation of early sclerotic lesions.