ICAM-1 expression is upregulated in reflux nephropathy

Reflux nephropathy (RN) is a major cause of end-stage renal failure in children and young adults. Intercellular adhesion molecule-1 (ICAM-1), a cell surface glycoprotein, has a role in the regulation of interaction among immune cells. It has been demonstrated that increased levels of tubular ICAM-1 correlate with an extent of tubular damage in diabetic nephropathy. We hypothesized that ICAM-1 local synthesis is altered in reflux nephropathy and therefore designated this study to investigate ICAM-1 expression in RN. The kidney specimens from six patients with severe reflux nephropathy secondary to primary vesicoureteral reflux were obtained at the time of nephrectomy. Control materials included normal kidney specimens obtained from three adult patients during partial nephrectomy for an incidentaloma. Fluorescent immunohistochemistry was carried out using monoclonal antibodies to ICAM-1 utilizing confocal laser scanning microscopy. Reverse transcriptase polymerase chain reaction (RT-PCR) was performed to evaluate the relative amount of ICAM-1. In the control kidneys, there was lack of ICAM-1 immunoreactivity in the interstitium and proximal tubules and moderate immunoreactivity in the glomerulus. In the refluxing kidney there was strong ICAM-1 immunoreactivity in the glomerulus, interstitium and proximal tubules. The RT-PCR showed strong ICAM-1 mRNA expression in the refluxing kidneys and absent or weak ICAM-1 expression in the controls. Our findings of increased expression of ICAM-1 in the severe reflux nephropathy kidney suggests that ICAM-1 may play a role in the pathogenesis of renal parenchymal damage associated with RN.