Evaluation of urinary biomarkers for early detection of acute kidney injury in a rat nephropathy model

Abstract

IntroductionThe implementation of novel, reliable biomarkers for the early and differential diagnosis of acute kidney injury (AKI) could greatly improve the timely treatment and prevention of disease progression, particularly since the current gold standards for detecting kidney injury such as serum creatinine (SCr) and blood urea nitrogen (BUN) lack sensitivity and specificity. We evaluated novel urinary kidney injury biomarkers focusing on early detection and better prediction of AKI with higher sensitivity and specificity. MethodsIn the rat, urinary biomarkers for kidney injury, i.e. albumin, beta-2-microglobulin (B2M), clusterin, cystatin C, kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), osteopontin (OPN), and total protein (TP), were investigated in an AKI model using different hyperosmolar and high-dose solutions, i.e. mannitol, sucrose, and contrast medium (CM), as acute single insults leading to kidney injury. Additionally, dose-dependency of sucrose was investigated and effects were compared to the sucrose- and iron-containing marketed drug Venofer®. ResultsLevels of excreted urinary biomarkers correlated with severity of AKI, exhibited a dose-dependent response to sucrose treatment, and demonstrated evidence of recovery from kidney injury with transient and reversible changes. The exceptions were KIM-1 and NGAL, which showed later responses following CM and iron-induced renal injury. All biomarkers outperformed plasma creatinine (PCr), BUN, and histopathology, with regard to practicability and/or detection of proximal tubular injury. DiscussionThe use of a panel of urinary kidney injury biomarkers emerged as an early, sensitive, and predictive tool to detect AKI showing enhanced sensitivity compared to current state-of-the-art markers.