Obesity has been firmly established as a major risk factor for common disease states including hypertension, type 2 diabetes mellitus, and chronic kidney disease. Increased body mass index (BMI) contributes to the activation of both the systemic and intra-tubular renin angiotensin systems (RAS), which are in turn associated with increased blood pressure (BP) and kidney damage. In this cross-sectional study, 43 subjects of normal or increased body weight were examined in order to determine the correlation of BMI or body fat mass (BFM) with blood pressure, fasting blood glucose (FBG), and urinary kidney injury markers such as interleukin-18 (IL-18), connective tissue growth factor (CTGF), neutrophil gelatinase-associated lipocalin, and kidney injury molecule-1 (KIM-1). Our results showed that: (1) subjects with increased body weight showed significantly higher BP, BFM, total body water and metabolic age; (2) BMI was positively correlated to both systolic (R2 = 0.1384, P = 0.01) and diastolic BP (R2 = 0.2437, P = 0.0008); (3) BFM was positively correlated to DBP (R2 = 0.1232, P = 0.02) and partially correlated to urine protein (R2 = 0.047, P = 0.12) and FBG (R2 = 0.07, P = 0.06); (4) overweight young adults had higher urinary mRNA levels of renin, angiotensinogen, IL-18 and CTGF. These suggest that BMI directly affects BP, kidney injury markers, and the activation of the intra-tubular RAS even in normotensive young adults. Given that BMI measurements and urine analyses are non-invasive, our findings may pave the way to developing a new and simple method of screening for the risk of chronic kidney disease in adults.

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.