Renal immunohistochemical distribution, plasma levels and urinary excretion of endothelin after kidney transplantation

We investigated the immunohistochemical distribution of endothelin (ET) in 22 graft biopsies from kidney-transplanted patients. Like normal kidney tissue, 6/22 biopsies showed either no or only very weak ET positivity in the vascular endothelium. In the other 16 cases ET staining was marked on the vascular endothelium and wall (9/16), inflammatory infiltrates (11/16), glomeruli (7/16) and tubules (5/16). ET positivity in glomeruli and inflammatory infiltrates correlated with the degree of glomerular damage and interstitial inflammation but no correlation was found between the immunohistochemical results and the clinical variables considered. ET plasma levels (ET-PL) in patients (5.13±1.77 pmol/L) did not differ significantly from age-matched healthy controls (3.76±0.93 pmol/L), nor did ET urinary excretion (ET-U/CR-U) (33.94±21.89 and 24.94±8.5 pmol/mmol/L respectively). Neither ET-PL nor ET-U/CR-U was correlated with histological and immunohistochemical data or with the clinical variables. Our study suggests a potential role of ET as a local pro-inflammatory and growth factor in renal allografts and confirms its importance in the sequence of events involved in the progression of kidney damage.