Augmented Urinary Excretion of Angiotensinogen Precedes Albuminuria in Human Young Adults with Overweight and Mice with High Fat Diet-Induced Type 2 Diabetes

Obesity is linked to the development of hypertension and type 2 diabetes (T2D) and both causing chronic kidney disease (CKD). Increased body mass index (BMI) and high fat diet (HFD) contribute to activation systemic renin angiotensin system (RAS). In addition, activation of intrarenal and intratubular RAS has been associated with increased pressure (BP), CKD, and augmentation of urinary excretion of angiotensinogen (uAGT) during T2D. However, whether augmentation of uAGT reflect intrarenal/intratububular RAS activation in subjects with overweight, remains unclear. Here, we tested the hypothesis that increases in uAGT precedes renal dysfunction in mice and human subjects with overweight, METHODS: C57BL/6 mice (N = 10) were fed either a normal fat diet (NFD) or HFD (45% Kcal from fat) for 28 weeks. During this period, metabolic phenotype along with urinary albumin, creatinine, reactive oxygen species (ROS) and AGT, were measured every 4 weeks. In addition, for evidence in humans (age 19-22 years-old), 11 individuals with overweight and 17 individuals with normal weight, were studied. In these subjects, anthropometric parameters, systolic and diastolic BP, fasting blood glucose (FBG), and urinary mRNA levels of AGT and kidney injury markers IL-18 and connecting tissue growth factor, were determined. Patients with history of cardiac or cerebrovascular events and endocrine diseases, anti-hypertensive treatment (ACE inhibitors, ARBs) and/or anti-diabetic drugs, were excluded RESULTS: In mice with metabolic alterations overtime, systolic BP significantly increased after 18 weeks in HFD but not NFD mice. Intrarenal ROS increased in HFD mice. These changes paralleled the augmentation uAGT excretion, which occurred in the absence of overt albuminuria. In human subjects with overweight, systolic and diastolic BP, urinary transcripts levels of AGT, renin, and injury markers IL-18 and CTGF were increased as compared to normal weight individuals. However, no significant changes were observed in proteinuria or albuminuria. CONCLUSIONS: Our results indicate that augmentation of uAGT precedes albuminuria in young human adults with overweight and mice during the development of HFD-induced T2D. These findings emphasize the relevance of uAGT and indicator of intrarenal/intratubular RAS activations and its potential as early biomarker of kidney injury during metabolic diseases as obesity and diabetes.