Expression Of KIM-1 And NGAL In Models Of Aminoglycosides-induced Nephrotoxicity

Aminoglycosides, which has widely used in clinical, was blocked in development progresses because of its nephrotoxicity. Owing to the poor sensitivity and specificity of traditional indicators in clinical, there is a need to find new biomarkers for earlier and more accurate detection of aminoglycosides evaluation.This research established models of aminoglycosides-induced nephrotoxicity in vivo and in vitro. The principal goal was to explore the value of two novel biomarkers in early renal injury and provide for toxicology information by studying the expressions of kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL).Experimental study is divided into two parts. In the first part of the study, expressions of KIM-1 and NGAL in kidneys of rats treated with Gentamicin were detected.45 male SD rats were injected with Gentamicin sulfate at 0,50 or 100 mg/kg/d (n=5 rats/dose group/time point) for up to 7 days and the animals were necropsied on days 1,3 or 7 for toxicity evaluation. SCr and BUN were measured using a standard clinical chemistry analyzer. Histopathology changes were observed by hematoxylin-eosin staining. Expressions of biomarkers were evaluated by quantitative real-time PCR and immunohistochemistry. In the second part of the study, expressions of KIM-1 and NGAL in vitro treated with Gentamicin and Netilmicin were detected. After HK-2 cells exposure to the two drugs for 2h,6h,12h,24h and 48h, expressions of biomarkers’mRNA were detected by quantitative real-time PCRThe results showed that after administrations of Gentamicin, SCr levels were significantly increased on Day7. BUN levels were increased in group of low-dose on Day7 and increased in group of high-dose on 1,3 and 7 days. Mild tubular cell degenerations were observed after Gentamicin (50mg/kg) treated for 7days and after Gentamicin (100mg/kg) treated for 3days. Disappearance of brush border of proximal tubules, tubular cell degenerations, necrosis, tubular dilatation, hyaline cast tubules and inflammation were observed in the Gentamicin-treated (100mg/kg) rats on Day7. Results of FQ-PCR showed that a dose- and time-dependent increase of the expression of KIM-1 and NGAL, which were found to correlate with the progressive histopathological alterations and preceded changes of clinical parameters indicative of impaired kidney function, were observed in Gentamicin treated rats. Consistent with gene expression analyses, KIM-1 and NGAL were undetectable in proximal tubules of control kidneys, but they were detected as early as 1 day in kidneys of both low-dose and high-dose animals. In contrast, no significant increase in the expression of the biomarker genes and proteins were evident in HK-2 cells after treated by Gentamycin and Netilmicin for up to 48h.The expressions of the two biomarkers changed prior to proximal tubule damage and increases in serum creatinine (SCr) and blood urea nitrogen (BUN) levels, suggesting their usefulness for predicting Gentamicin-induced acute kidney injury (AKI) in vivo. However, they may not be suitable endpoints for sensitive detection of nephrotoxic effects in vitro.