Journal Article

Urinary angiotensinogen reflects the activity of intrarenal renin–angiotensin system in patients with IgA nephropathy

Akira Nishiyama, Yoshio Konishi, Naro Ohashi, Takashi Morikawa, Maki Urushihara, Isseki Maeda, Masahiro Hamada, Masatsugu Kishida, Hirofumi Hitomi, Nobuo Shirahashi, Hiroyuki Kobori and Masahito Imanishi

in Nephrology Dialysis Transplantation

Published on behalf of European Renal Association - European Dialysis and Transplant Assoc

Volume 26, issue 1, pages 170-177
Published in print January 2011 | ISSN: 0931-0509
Published online July 2010 | e-ISSN: 1460-2385 | DOI: http://dx.doi.org/10.1093/ndt/gfq371
Urinary angiotensinogen reflects the activity of intrarenal renin–angiotensin system in patients with IgA nephropathy

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Background. A potential contribution of local activation of the renin–angiotensin system (RAS) to the pathogenesis of renal injury has been indicated by evidence for blood pressure-independent renoprotective effects of angiotensin II (AngII) receptor blockers (ARBs). The present study was performed to test the hypothesis that urinary angiotensinogen provides a specific index of intrarenal RAS status in patients with immunoglobulin A (IgA) nephropathy.

Methods. This paper is a survey of urine specimens from three groups: healthy volunteers, patients with IgA nephropathy and patients with minor glomerular abnormality (MGA). Patients with hypertension, diabetes, reduced glomerular filtration rate and/or who were under any medication were excluded from this study. Urinary angiotensinogen levels were measured by a sandwich enzyme-linked immunosorbent assay system.

Results. Urinary angiotensinogen levels were not different between healthy volunteers and patients with MGA. However, urinary angiotensinogen levels, renal tissue angiotensinogen expression and AngII immunoreactivity were significantly higher in patients with IgA nephropathy than in patients with MGA. Baseline urinary angiotensinogen levels were positively correlated with renal angiotensinogen gene expression and AngII immunoreactivity but not with plasma renin activity or the urinary protein excretion rate. In patients with IgA nephropathy, treatment with an ARB, valsartan (40 mg/day), significantly increased renal plasma flow and decreased filtration fraction, which were associated with reductions in urinary angiotensinogen levels.

Conclusion. These data indicate that urinary angiotensinogen is a powerful tool for determining intrarenal RAS status and associated renal derangement in patients with IgA nephropathy.

Keywords: angiotensin II; angiotensinogen; IgA nephropathy; urinary biomarker; valsartan

Journal Article.  4616 words.  Illustrated.

Subjects: Nephrology

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