C-Type natriuretic peptide: a potential urinary biomarker for renal remodeling and fibrosis during aging

Background Renal aging is characterized by structural changes in the kidney, including fibrosis, which are often accompanied by reduced glomerular filtration rate (GFR) and elevated urinary protein excretion (UPE) that likely contributes to increased risk of kidney failure, cardiovascular disease and mortality in the elderly. Importantly a recent study, using biopsy in healthy kidney donors across six decades of life, demonstrated the presence of preclinical agerelated nephropathy which was otherwise undetectable using conventional clinical tests including GFR and UPE. Although, there are a number of biomarkers for renal disease and injury, there are few which target early renal remodeling prior to the onset of symptoms during natural aging. C-type natriuretic peptide (CNP) is highly expressed in renal cells, is potently anti-fibrotic, inhibits renal mesangial matrix accumulation and may play a role in podocyte-glomerular basement membrane (GBM) integrity. Since aging is associated with altered renal structure and function that may contribute to the development of kidney and heart failure, we sought to determine if CNP might serve as a urinary biomarker for global renal remodeling as a compensatory renal response to injury induced by aging.