Urinary angiotensinogen levels reflect the severity of renal histopathology in patients with chronic kidney disease

Abstract

Recent studies have suggested that urinary angiotensinogen (AGT) reflects the activity of the intrarenal renin angiotensin system (RAS), which is involved in tissue injury in patients with chronic kidney disease. In this study, we investigated whether urinary AGT directly reflected the severity of histopathology in such patients. AGT was measured using a sandwich enzyme-linked immunosorbent assay (ELISA) on urine and plasma samples obtained from 58 patients on the day of renal biopsy. We measured the urinary transforming growth factor (TGF)-beta1, a representative cytokine of fibrogenic property, and analyzed the correlation among urinary TGF-beta1, urinary AGT, and the severity of renal injury. Mesangial proliferation, glomerulosclerosis, tubular atrophy and interstitial fibrosis were scored for the biopsied tissues. Urinary AGT levels correlated positively with proteinuria, urinary TGF-beta1 levels and diastolic blood pressure, but negatively with the estimated glomerular filtration rate (GFR). Urinary AGT concentrations were increased in patients with severe glomerulosclerosis, tubular atrophy and interstitial fibrosis. Urinary AGT levels correlated with the deterioration of renal function in patients with chronic kidney disease and reflected the histological severity of renal injury.