Circulating adhesion molecules and neutral endopeptidase enzymuria in patients with urolithiasis and hydronephrosis

Abstract

Objectives. To measure the concentrations of adhesion molecules (intercellular adhesion molecule-1 [ICAM-1], E-selectin, and L-selectin) in the serum of patients with renal stones and patients with hydronephrosis caused by obstructive ureteral stones. Renal tubular enzymes were examined from their urine samples to evaluate whether neutral endopeptidase (NEP) behaved as traditional tubular enzyme markers ( N-acetyl-β-glucosaminidase [NAG] and β-galactosidase [β-GAL]) in their disease state. Methods. Three groups were studied. Group 1 included 15 normal volunteers, group 2 included 12 patients with ureteral stones and ipsilateral hydronephrosis, and group 3 included 17 patients with renal stones in one kidney without hydronephrosis or hydrocalycosis. A single, overnight fasting blood and urine sample was collected from each subject. Serum levels of ICAM-1, E-selectin, and L-selectin were measured by enzyme-linked immunosorbent assay. NEP, NAG, and β-GAL were measured from urine samples, and the enzyme activities were expressed per gram of creatinine. Results. Serum levels of ICAM-1 were higher in groups 2 and 3 (522 ± 95 and 329 ± 42 ng/mL, respectively), but the differences were only significant between group 2 and group 1 (263 ± 32 ng/mL) and group 2 and group 3 ( P <0.05). Serum levels of L-selectin were lower in group 3 and were significantly different when compared with groups 1 and 2 ( P <0.05). The serum levels of E-selectin were not significantly different among these three groups. Urinary levels of NEP were lower in group 2, although the levels of NAG and β-GAL were more elevated than in group 1. Conclusions. Serum levels of ICAM-1 were elevated in patients with unilateral hydronephrosis caused by a ureteral stone, and E-selectin and L-selectin levels did not change significantly. These findings suggest that ICAM-1 may play a role in renal immune injury to ureteral obstruction. The urinary NEP values were lower in patients with hydronephrosis caused by ureteral stones, and the traditional lysosomal enzymes were increased. The lower urinary NEP values might suggest impairment of ipsilateral renal function. Renal stones per se resulted in no significant changes in serum adhesion molecule levels, although the levels of L-selectin were significantly decreased.