Osteopontin as a Biomarker for Early Diagnosis of Renal Damage during Experimental Metabolic Syndrome

Background: Excess consumption of fructose is a significant factor in the development of metabolic syndrome (MetS). It may also play a role in the progress of chronic kidney disease (CKD). Osteopontin (OPN) is a pleiotropic, multi-phosphorylated glycoprotein which plays important roles in diseases as well as in a wide range of biological activities. Based on these findings, the aim of this study was to evaluate OPN as a biomarker for the early detection of renal injury during an experimental model of fructose associated MetS in mice.Methods: Male CD1 mice aged 8-10 weeks were used. Fructose mice were given 30% fructose solution in drinking water, while control mice were given normal drinking water for 56 days. At sacrifice, kidneys, blood and urine of mice were collected. Bio-chemical, histological (hematoxylin and eosin and Masson's trichrome), immunohistochemical and molecular analyses (western blot, real-time quantitative polymerase chain reaction (RT-qPCR)) were performed.Results: Compared to controls, Fructose mice showed increased levels of glucose, total cholesterol (TC), triglyceride (TG), low-density lipoprotein (LDL), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), as well as creatinine and blood urea nitrogen (BUN). In addition, significant histological kidney injury and fibrosis were observed in Fructose mice. These alterations were associated with increased levels of plasma and renal tissue OPN. Conclusions: Thus, new biomarkers such as OPN can be clinically useful to help predict kidney damage in MetS.