Urinary Angiotensinogen Displays Sexual Dimorphism in Non-Diabetic Humans and Mice with Overweight.

Increased body weight (BW) induces inappropriate renin-angiotensin system (RAS) activation. The activation of the intrarenal RAS is associated with increased urinary angiotensinogen (uAGT), blood pressure (BP), and kidney damage. Here, we examined uAGT excretion levels in young non-diabetic human subjects with overweight (OW) and non-diabetic mice with high-fat diet (HFD)-induced OW. Human subjects (women and men; 20-28 years old) included two groups: (a) overweight (OW, n = 17, BMI ≥ 25); and (b) controls (normal weight (NW; n = 26, BMI ≤ 25). In these subjects, we measured BP, albuminuria, and protein levels of uAGT by ELISA adjusted by urinary creatinine (expressed by uAGT/uCrea). Mice (female and male C57BL/6J mice, 8 ± 2 weeks of age) also included two groups: HFD or normal fat diet (NFD) fed for 8 weeks. We measured BW, fasting blood glucose (FBG), BP by telemetry, albuminuria, and uAGT by ELISA. In humans: (i) no significant changes were observed in BP, albuminuria, and FBG when comparing NW and OW subjects; (ii) multivariate logistic regression analysis of independent predictors related to uAGT/uCrea levels demonstrated a strong association between uAGT and overweight; (iii) urinary reactive oxygen species (ROS) were augmented in men and women with OW; (iv) the uAGT/uCrea ratio was higher in men with OW. However, the uAGT/uCrea values were lower in women even with OW. In mice: (i) males fed an HFD for 8 weeks became OW while females did not; (ii) no changes were observed either in FBG, BP, or albuminuria; (iii) kidney ROS were augmented in OW male mice after 28 weeks but not in females; (iv) OW male mice showed augmented excretion of uAGT but this was undetectable in females fed either NFD or HFD. In humans and mice who are OW, the urinary excretion of AGT differs between males and females and overcomes overt albuminuria.

Serum and urinary angiotensinogen levels as prognostic indicators in acute kidney injury: a prospective study.

OBJECTIVE: The delayed increase in serum creatinine levels poses challenges in the timely diagnosis of acute kidney injury. This study aimed to investigate the relationship between serum angiotensinogen and urinary angiotensinogen levels and the prognosis of renal function in patients diagnosed with acute kidney injury. METHODS: A total of 79 newly diagnosed acute kidney injury patients aged 18 years and older were enrolled. Serum angiotensinogen and urinary angiotensinogen levels were measured at the onset of the disease, as well as on the 15th and 30th days of follow-up. After 3 months, renal function was evaluated by measuring serum creatinine levels. RESULTS: Among the acute kidney injury patients, those in Kidney Disease: Improving Global Outcomes stage 3 exhibited significantly higher urinary angiotensinogen/urine creatinine levels compared with stages 1 and 2 patients at the time of diagnosis (p<0.05). Furthermore, a positive correlation was observed between the urinary angiotensinogen/urine creatinine level at the time of diagnosis and the serum creatinine level at the third month (r=0.408, p=0.048). CONCLUSION: The findings suggest that urinary angiotensinogen levels can serve as an indicator of the severity of acute kidney injury. Monitoring urinary angiotensinogen levels could potentially contribute to the prognosis assessment and management of acute kidney injury patients.

Relationship Between Urinary Angiotensinogen and Mortality in Patients with Heart Failure with Reduced Ejection Fraction.

BACKGROUND: Activation of the reninangi otens in-aldosterone system has an important role in the pathophysiology of heart failure with reduced ejection fraction. While the effects of systemic reninangi otens in-aldosterone system activation on heart failure with reduced ejection fraction are well known, the impact of the local reninangi otens in-aldosterone system on heart failure with reduced ejection fraction is not fully understood because of limited clinical research. This study aimed to investigate the effect of urinary angiotensinogen level, an accepted indicator of local reninangi otens in-aldosterone system activation, on all-cause mortality in patients with heart failure with reduced ejection fraction. METHODS: This retrospective, single-center study included 60 patients with baseline urinary angiotensinogen data and survival/mortality data at 4 years. Urinary angiotensinogen values were standardized to the urinary creatinine value measured from the same urine sample. The median urinary angio tensi nogen /urin ary creatinine value among all patients (114 µg/g) was used as a cutoff to divide the patients into 2 groups. Mortality data were obtained from the national registry systems or by telephone. RESULTS: Comparison of all-cause mortality in the 2 groups showed that 22 deaths (71%) occurred in the group with a urinary angio tensinogen/urinary creatinine ratio above the median and 10 deaths (35.5%) occurred in the group of patients with urinary angio tensinogen/urinary creatinine equal to or below the median value (P =.005). CONCLUSION: Our study suggests that urinary angiotensinogen can be used as a new biomarker in the prognosis and follow-up of heart failure patients.

Intrarenal renin-angiotensin system activation and macrophage infiltrations in pediatric chronic glomerulonephritis.

BACKGROUND: The current study tested the hypothesis that urinary angiotensinogen (UAGT) and urinary monocyte chemoattractant protein-1 (UMCP-1) levels provide a specific index of intrarenal renin-angiotensin system (RAS) status and the degree of infiltration of macrophages associated with RAS blockade and immunosuppressant treatment in pediatric patients with chronic glomerulonephritis. METHODS: We measured baseline UAGT and UMCP-1 levels to examine the correlation between glomerular injury in 48 pediatric chronic glomerulonephritis patients before treatment. Furthermore, we performed immunohistochemical analysis of angiotensinogen (AGT) and CD68 in 27 pediatric chronic glomerulonephritis patients treated with RAS blockades and immunosuppressants for 2 years. Finally, we examined the effects of angiotensin II (Ang II) on monocyte chemoattractant protein-1 (MCP-1) expression in cultured human mesangial cells (MCs). RESULTS: Baseline UAGT and UMCP-1 levels positively correlated with urinary protein levels, scores for mesangial hypercellularity, rate of crescentic formation, and expression levels of AGT and CD68 in renal tissues (p < 0.05). UAGT and UMCP-1 levels were significantly decreased after RAS blockade and immunosuppressant treatment (p < 0.01), which was accompanied by AGT and CD68 (p < 0.01), as well as the magnitude of glomerular injury. Cultured human MCs showed increased MCP-1 messenger ribonucleic acid and protein levels after Ang II treatment (p < 0.01). CONCLUSIONS: The data indicates that UAGT and UMCP-1 are useful biomarkers of the degree of glomerular injury during RAS blockade and immunosuppressant treatment in pediatric patients with chronic glomerulonephritis.

Urinary angiotensinogen is associated with albuminuria in adults with sickle cell anaemia.

We explored the association of novel urinary biomarkers with albumin-creatinine ratio (ACR) in adults with sickle cell anaemia. Of 37 participants, 13 (35.2%) had persistent albuminuria (PA). Urinary levels of clusterin (p = 0.002), retinol-binding protein 4 (p = 0.008), alpha-1 microglobulin (p = 0.002) and angiotensinogen (p = 0.006) were significantly higher in participants with PA than in those without PA. Although univariate analysis showed significant associations between both alpha-1 microglobulin (p = 0.035) and angiotensinogen (p = 0.0021) with ACR, only angiotensinogen was associated with ACR in multivariable analysis (p = 0.04). Our results suggest that urinary angiotensinogen may identify sickle cell anaemia patients at risk for kidney disease.

[Clinical value of renal artery resistance index and urinary angiotensinogen in early diagnosis of acute kidney injury in patients with sepsis].

OBJECTIVE: To investigate the value of renal artery resistance index (RRI) and urinary angiotensinogen (UAGT) in the early diagnosis of acute kidney injury (AKI) in patients with sepsis. METHODS: A prospective study was conducted. Seventy-eight patients with sepsis admitted to the department of critical care medicine of General Hospital of Ningxia Medical University from January to September 2021 were enrolled. Patients were observed for the development of AKI within 1 week. General data [gender, age, body mass index (BMI), major infection sites and critical illness related scores], laboratory indicators [mean arterial pressure (MAP), central venous pressure (CVP), procalcitonin (PCT), arterial blood lactic acid (Lac), etc.], duration of mechanical ventilation and length of intensive care unit (ICU) stay were recorded. After hemodynamic stabilization of the patients, renal ultrasound was performed to measure the RRI within 24 hours after ICU admission. Urine samples were taken immediately after diagnosis, and the level of UAGT was detected by enzyme-linked immunosorbent assay (ELISA). The above parameters were compared between the two groups. Multivariate Logistic regression was used to analyze the risk factors of AKI in patients with sepsis. Receiver operator characteristic curve (ROC curve) was drawn to analyze the predictive value of related indicators for AKI in sepsis. RESULTS: A total of 78 patients were finally enrolled, of which 45 developed AKI and 33 did not. Compared with the non-AKI group, the rates of vasoactive drugs use, 28-day mortality, sequential organ failure assessment (SOFA) score, acute physiology and chronic health evaluation II (APACHE II) score, PCT, Lac, RRI and UAGT were significantly higher in the AKI group [rates of vasoactive drugs use: 68.9% vs. 39.4%, 28-day mortality: 48.9% vs. 24.2%, SOFA score: 12.0 (10.5, 14.0) vs. 8.0 (7.0, 10.0), APACHE II score: 22.0 (18.0, 27.5) vs. 16.0 (15.0, 18.5), PCT (µg/L): 12.5±2.6 vs. 10.9±2.8, Lac (mmol/L): 2.6 (1.9, 3.4) vs. 1.9 (1.3, 2.6), RRI: 0.74±0.03 vs. 0.72±0.02, UAGT (µg/L): 75.16±19.99 vs. 46.28±20.75, all P < 0.05], the duration of mechanical ventilation and the length of ICU stay were significantly prolonged [duration of mechanical ventilation (days): 8.0 (7.0, 12.0) vs. 5.0 (4.0, 6.0), length of ICU stay (days): 14.0 (10.0, 16.0) vs. 9.0 (8.0, 11.5), both P < 0.01], and MAP was significantly lowered [mmHg (1 mmHg ≈ 0.133 kPa): 68.5±11.2 vs. 74.2±12.8, P < 0.05]. There was no significant difference in other parameters between the two groups. Multivariate Logistic regression analysis showed that SOFA score [odds ratio (OR) = 2.088, 95% confidence interval (95%CI) was 1.322-3.299], APACHE II score (OR = 1.447, 95%CI was 1.134-1.845), RRI (OR = 1.432, 95%CI was 1.103-1.859), and UAGT (OR = 1.077, 95%CI was 1.035-1.121) were independent risk factors for sepsis complicated with AKI (all P < 0.01). ROC curve analysis showed that SOFA score, APACHE II score, RRI and UAGT had certain predictive value for AKI in septic patients, the area under the ROC curve (AUC) were 0.814 (95%CI was 0.716-0.912), 0.804 (95%CI was 0.708-0.901), 0.789 (95%CI was 0.690-0.888), and 0.840 (95%CI was 0.747-0.934), respectively, and the AUC of RRI combined with UAGT was 0.912 (95%CI was 0.849-0.974), which was better than the above single index (all P < 0.05). CONCLUSIONS: RRI combined with UAGT has a high early predictive value for septic AKI.

Effects of Exercise Training on the Renin-Angiotensin System in the Kidneys of Dahl Salt-Sensitive Rats.

PURPOSE: Exercise training (Ex) has antihypertensive and renal protective effects; however, the precise mechanisms remain unclear. The renal renin-angiotensin system (RAS) plays a vital role in renal function and pathology. Therefore, we investigated the effects of Ex on the renal RAS components in Dahl salt-sensitive (Dahl-S) rats. METHODS: Male Dahl-S rats were divided into four groups: normal salt diet + sedentary, normal salt diet + Ex, high-salt diet (HS, 8% NaCl) + sedentary, and HS + Ex. Treadmill running was performed for 8 wk in the Ex groups. RESULTS: Ex attenuated the HS-induced renal dysfunction and glomerular injury without causing blood pressure alterations. HS increased urinary excretion of both total and intact angiotensinogen. Ex decreased the HS-induced increased urinary excretion of total angiotensinogen. However, it did not change the HS-induced urinary excretion of intact angiotensinogen, indicating reduced intact angiotensinogen cleaving. Ex restored the HS-induced increased angiotensinogen and angiotensin II type 1 receptor expressions in the outer medulla and the HS-induced increased angiotensin-converting enzyme expression in the cortex. Ex restored the HS-induced decreased renin expression in the cortex and outer medulla, and the HS-induced decreased angiotensin-converting enzyme 2, angiotensin II type 2 receptor, and Mas receptor expressions in the outer medulla. CONCLUSIONS: Ex attenuates HS-induced renal dysfunction, glomerular injury, and renal RAS dysregulation in Dahl-S rats.

Reduced urinary angiotensinogen excretion in preeclampsia.

OBJECTIVE: This study evaluated urinary angiotensinogen in preeclampsia. METHODS: Normal pregnant (n = 57) and preeclamptic patients (n = 31); Normal pregnant (n = 10) and preeclamptic rats (n = 10) were studied. Urinary angiotensinogen and plasma angiotensin II were assayed by enzyme-linked immunosorbent assay (ELISA). RESULTS: Urinary angiotensinogen in preeclampsia patients (2.0 ± 1.1 ng/mg creatinine) was suppressed (*p < 0.05) compared to normal pregnant (2.7 ± 1.5 ng/mg creatinine). Plasma angiotensin II in preeclampsia patients (preeclampsia: 36.2 ± 7; normal pregnant: 48.1 ± 5 fmol/mL) was lower. The similar result was observed in preeclampsia rat model. CONCLUSIONS: The reduced urinary excretion of angiotensinogen was both in human preeclampsia patients and rat model of preeclampsia.

Coregulation Analysis of Mechanistic Biomarkers in Autosomal Dominant Polycystic Kidney Disease.

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disorder leading to deterioration of kidney function and end stage kidney disease (ESKD). A number of molecular processes are dysregulated in ADPKD but the exact mechanism of disease progression is not fully understood. We measured protein biomarkers being linked to ADPKD-associated molecular processes via ELISA in urine and serum in a cohort of ADPKD patients as well as age, gender and eGFR matched CKD patients and healthy controls. ANOVA and t-tests were used to determine differences between cohorts. Spearman correlation coefficient analysis was performed to assess coregulation patterns of individual biomarkers and renal function. Urinary epidermal growth factor (EGF) and serum apelin (APLN) levels were significantly downregulated in ADPKD patients. Serum vascular endothelial growth factor alpha (VEGFA) and urinary angiotensinogen (AGT) were significantly upregulated in ADPKD patients as compared with healthy controls. Arginine vasopressin (AVP) was significantly upregulated in ADPKD patients as compared with CKD patients. Serum VEGFA and VIM concentrations were positively correlated and urinary EGF levels were negatively correlated with urinary AGT levels. Urinary EGF and AGT levels were furthermore significantly associated with estimated glomerular filtration rate (eGFR) in ADPKD patients. In summary, altered protein concentrations in body fluids of ADPKD patients were found for the mechanistic markers EGF, APLN, VEGFA, AGT, AVP, and VIM. In particular, the connection between EGF and AGT during progression of ADPKD warrants further investigation.

Newly developed radioimmunoassay for Human Angiotensin-(1-12) measurements in plasma and urine.

The dodecapeptide angiotensin-(1-12) [Ang-(1-12)] functions as an intracrine/paracrine substrate for local production of angiotensin II. We developed a reliable and specific radioimmunoassay (RIA) method for the measurement of Ang-(1-12) in human plasma and urine using an affinity purified antibody fraction directed towards the C-terminus of the human Ang-(1-12) sequence. The RIA method was applied to quantify the Ang-(1-12) in plasma and urine collected from thirty-four human subjects (29 treated with antihypertensive medicines and 5 untreated patients). Plasma Ang-(1-12) level was significantly higher (P < 0.05) in patients with systolic blood pressure ≥140 mm Hg (n = 10) compared to the group with systolic blood pressure <140 mm Hg (n = 24). No significant difference (P = 0.22) was found in spot urine between the groups. Our study also shows that the polyclonal antibody neutralizes the cleavage sites of the human Ang-(1-12) from recombinant human chymase (rhChymase) and serum angiotensin converting enzyme (ACE) mediated Ang II generating hydrolysis. Overall, this newly developed RIA method is reliable and applicable to accurately quantify the Ang-(1-12) level in clinical samples (plasma and urine). Further, our in vitro neutralization study suggests that the anti-Ang-(1-12)-antibody might be used as an in vivo therapeutic agent for preventing Ang-(1-12)/Ang II-mediated hypertension and organ damage.

Interrelationship between renin-angiotensin-aldosterone system and oxidative stress in chronic heart failure patients with or without renal impairment.

We investigated oxidative stress and RAAS biomarkers, as well as their association, in chronic heart failure (CHF) patients on optimized medical therapy, stratified by disease severity or by renal function. Since vitamin D has been shown to attenuate RAAS activation and oxidative stress, we further evaluated the relationship between vitamin D, RAAS and oxidative stress in CHF patients with or without renal impairment. Sixty CHF outpatients were included and stratified by disease severity or by renal function. We quantified urinary hydrogen peroxide, plasma and urinary isoprostanes, plasma total antioxidant status, urinary angiotensinogen (intrarenal RAAS activation biomarker) and plasma angiotensinogen, plasma renin and aldosterone concentration, serum angiotensin-converting enzyme (ACE) activity, plasma angiotensin peptides, and serum total 25-hydroxyvitamin D (S-total 25(OH)D). Severe CHF patients had higher urinary isoprostanes (p = 0.002) and lower S-total 25(OH)D (p = 0.006) compared to mild-to-moderate patients, but no differences were observed for other redox or RAAS biomarkers. Patients with impaired renal function (iRF) had higher urinary angiotensinogen (p = 0.003) and lower S-total 25(OH)D (p = 0.028) compared to those with normal renal function (nRF), while no differences were observed for the remaining RAAS and redox parameters. Several positive correlations between oxidative stress and RAAS biomarkers were detected in iRF patients, while in patients with nRF these correlations were primarily inverse. In CHF-iRF patients, S-25(OD)D was inversely associated with urinary isoprostanes, which in turn were positively associated with plasma angiotensinogen and serum ACE. In conclusion, CHF patients with renal function impairment have increased intrarenal RAAS activation and lower vitamin D values and might benefit from the combination of RAAS blockers with vitamin D and/or antioxidants.

Time Course Changes in Urinary Angiotensinogen and Circulating N-Terminal Pro-B-Type Natriuretic Peptide in Patients Hospitalized with Acute Heart Failure.

Objective Home care is important in patients with heart failure (HF) in order to maintain their quality of life. A biomarker that can be measured noninvasively is needed to optimize the home care of patients with HF. Urinary angiotensinogen (uAGT) is an indicator of the intrarenal renin-angiotensin system activity, which may be augmented in HF. We hypothesized that uAGT might be a urinary biomarker in HF. Methods We measured uAGT by an enzyme-linked immunosorbent assay and uAGT normalized by urinary creatinine (uCr)-designated uAGT/uCr-at admission and discharge in 45 patients hospitalized for HF. Results We found that both uAGT/uCr [median (interquartile range): 65.5 (17.1-127.7) µg/g Cr at admission; 12.1 (6.0-37.0) µg/g Cr at discharge; p<0.01] and N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels [5,422 (2,280-9,907) pg/mL at admission; 903 (510-1,729) pg/mL at discharge; p<0.01] significantly decreased between admission and discharge along with an improvement in patient's clinical status [New York Heart Association scores: 3 (3-4) at admission; 1 (1-1) at discharge; p<0.01]. The generalized least squares model revealed that the time course changes in uAGT/uCr also correlated with those in NT-proBNP levels between admission and readmission in five patients readmitted for HF. Conclusion The results indicated that the time course changes in uAGT/uCr correlated with those in the NT-proBNP levels in patients with HF who showed a clinical improvement. Further investigation and development of a kit for the rapid measurement of uAGT are needed to evaluate the clinical utility of uAGT as a biomarker in HF.

Chronotherapy with a Renin-angiotensin System Inhibitor Ameliorates Renal Damage by Suppressing Intrarenal Renin-angiotensin System Activation.

Objective The intrarenal renin-angiotensin system (RAS) is activated in chronic kidney disease (CKD) patients and is not suppressed at night in CKD patients showing nocturnal hypertension, contributing to renal damage. Furthermore, changes in RAS inhibitor administration from morning to evening, namely chronotherapy, ameliorates renal damage at night. We attempted to clarify whether or not chronotherapy ameliorates renal damage by suppressing the intrarenal RAS activity. Methods We recruited 34 CKD patients with RAS inhibitors in the morning. We conducted ambulatory blood pressure (BP) monitoring and urine collection and evaluated urinary albumin (Alb) and angiotensinogen (AGT), which are surrogate markers for intrarenal RAS activity during the day and at night, respectively. The same experiments were conducted after changing the administration time. The ratio of values associated with morning versus evening dosing was defined as the morning to evening (M/E) ratio. Results The M/E ratio of urinary Alb had a significant and positive relationship with that of urinary AGT during the day and at night in all CKD patients. However, no significant relationships were found between the M/E ratios of urinary Alb and AGT using multiple linear regression analyses. Conversely, there was a significant and positive relationship between the M/E ratios of urinary Alb and AGT at night but not during the day in CKD patients whose estimated glomerular filtration rate was <45 mL/min/1.73 m2 and whose night-to-day ratio of systolic BP was >0.90, even after adjustment. Conclusion This study indicated that chronotherapy with RAS inhibitors improved the renal damage via intrarenal RAS suppression, especially in CKD patients with an impaired renal function and nocturnal hypertension.

Urinary Angiotensinogen in addition to Imaging Classification in the Prediction of Renal Outcome in Autosomal Dominant Polycystic Kidney Disease.

BACKGROUND: Intrarenal renin-angiotensin system (RAS) is known to play the major role in the development of hypertension and renal progression in autosomal dominant polycystic kidney disease (ADPKD). Urinary angiotensinogen to creatinine ratio (AGT/Cr) was suggested as a novel biomarker to reflect intrarenal RAS activity. This study was performed to evaluate urinary AGT/Cr as a predictive biomarker for renal function decline in addition to imaging classification in a prospective ADPKD cohort. METHODS: From 2011 to 2016, a total of 364 ADPKD patients were enrolled in the prospective cohort called the KoreaN Cohort Study for Outcomes in Patients With Chronic Kidney Disease (KNOW-CKD). Among them, a total of 207 subjects in chronic kidney disease stage 1-4 with baseline urinary AGT and total kidney volume and subsequent renal function follow-up data over more than 1 year were included in the analysis. Patients were defined as slow progressors (SP) if they are classified as 1A or 1B by imaging classification whereas rapid progressors (RP) if they are classified as 1C-1E. Patients were divided according to AGT/Cr quartiles and annual estimated glomerular filtration rate (eGFR) slope was compared among highest quartile (hAGT group) and the rest of quartiles (lAGT group). Patients were divided into 4 groups to evaluate the predictive value of urinary AGT/Cr in addition to imaging classification: SP/lAGT, SP/hAGT, RP/lAGT, and RP/hAGT. The Cox regression model was used to evaluate the hazard ratio (HR) between groups. RESULTS: The mean age was 45.9 years and 88.9% had hypertension. Baseline eGFR was 79.0 ± 28.4 mL/min/1.73 m² and median height-adjusted total kidney volume was 788.2 (471.2; 1,205.2) mL/m. The patients in the hAGT group showed lower eGFR (72.4 ± 24.8 vs. 81.1 ± 29.2 mL/min/1.73 m², P = 0.039), lower plasma hemoglobin (13.0 ± 1.4 vs. 13.7 ± 1.6 g/dL, P = 0.007), higher urinary protein to creatinine ratio (0.14 [0.09, 0.38] vs. 0.07 [0.04, 0.12] g/g, P = 0.007) compared to the lAGT group. The hAGT group was an independent risk factor for faster eGFR decline after adjusting for gender, RP, baseline eGFR, and other known risk factors. During median follow-up duration of 4.6 years, a total of 29 renal events (14.0%) occurred. The SP/hAGT group showed significantly higher risk of developing renal outcome compared to SP/lAGT group (HR, 13.4; 95% confidence interval, 1.282-139.324; P = 0.03). CONCLUSION: Urinary AGT/Cr can be a useful predictive marker in the patients with relatively small ADPKD. Various biomarkers should be considered to define RP when implementing novel treatment in the patients with ADPKD.

Urinary angiotensinogen as a surrogate marker predicting the antiproteinuric effects of angiotensin receptor blockers in patients with overt proteinuria: a multicenter prospective study.

BACKGROUND: Although urinary angiotensinogen (AGT) and renin reflect intrarenal renin-angiotensin system activity and are enhanced in proteinuric chronic kidney disease, the clinical value of urinary AGT and renin levels during antiproteinuric treatment has yet to be determined. We investigated the clinical usefulness of initial urinary AGT or renin to determine the antiproteinuric effects of angiotensin receptor blockers (ARBs). METHODS: This multicenter, prospective, single-arm study included 205 patients with overt proteinuria (urinary protein/creatinine ratio [uPCR] ≥ 1 mg/mg) enrolled between April 2009 and December 2011. All patients were treated with valsartan. The urinary AGT/creatinine ratio (uAGT/Cr) was measured at the baseline and 24 weeks, and the renin/creatinine ratio (uR/Cr) was measured at the baseline. Fifty-six patients were followed-up for 5 years. RESULTS: The mean age was 47.6 years and 51.2% were male. The mean uPCR was 2.32 mg/mg and the mean eGFR was 63.2 mL/min/1.73m2. Natural logarithms (ln) (uAGT/Cr), ln(uR/Cr), and diabetes mellitus were associated with proteinuria decrement (decrease in uPCR ≥1 mg/mg). Ln(uAGT/Cr) was an independent predictor for proteinuria decrement (OR 1.372, 95% CI, 1.068-1.762, P = 0.013). Among the 56 patients followed-up for 5 years, Δln(uAGT/Cr) at 24 weeks was an independent predictor for uPCR < 1 mg/mg at 5 years (OR 0.379, 95% CI, 0.20-0.715, P = 0.003). CONCLUSIONS: Our study demonstrates the potential role of both baseline urinary AGT and changes in urinary AGT during the initial 24 weeks as surrogate markers predicting the antiproteinuric effects of ARBs in patients with overt proteinuria.

Reduction in urinary angiotensinogen levels and improvement of proteinuria by renin-angiotensin system blockade in pediatric chronic kidney disease patients with very low birth weight.

BACKGROUND: Children with low birth weight (LBW) have an increased risk of developing chronic kidney disease (CKD), and no effective strategies have been established to prevent the progression of CKD in these patients. Urinary angiotensinogen (UAGT) may represent a useful marker of intrarenal renin-angiotensin system (RAS) activation, which has been suggested to play a critical role in the development of hypertension and CKD. Herein, we conducted a prospective study to determine whether RAS blockade is beneficial for suppressing the progression of CKD in children with LBW, using UAGT as a surrogate marker of renal impairment. METHODS: Nine children with CKD (stages: 1-2) who had very low birth weight (VLBW; < 1500 g) were started on RAS blockade with candesartan. We measured blood pressure and laboratory parameters, including urinary concentrations of angiotensinogen, protein, albumin, creatinine (Cr), and estimated glomerular filtration rate (eGFR), before and after candesartan treatment. RESULTS: Birth weight was 712 g (range, 536-800 g). Age at evaluation was 11.6 years (range, 10.3-15.6 years). After candesartan treatment for 47.6 ± 25.0 months, the UAGT to urinary Cr ratio decreased from 61.9 ± 44.7 to 16.8 ± 14.4 µg/g (p = 0.015). The urinary protein to Cr and albumin to Cr ratios also decreased (p = 0.008 and p = 0.012, respectively), whereas there was no significant change in eGFR. CONCLUSIONS: RAS blockade reduced UAGT levels and improved proteinuria/albuminuria in children with CKD who had VLBW. Suppression of intrarenal RAS activity may slow the progression of CKD in children with LBW.

The Urinary Angiotensinogen to Urinary Albumin Ratio Reflects Whether the Renin-angiotensin System in the Kidney Is Activated due to Filtration of Plasma Angiotensinogen through the Damaged Glomeruli or the Production of Angiotensinogen in the Proximal Tubules.

Objective Urinary angiotensinogen (AGT) is a surrogate marker for intrarenal renin-angiotensin system (RAS) activity that plays an important role in the development of renal damage. Urinary AGT levels are determined by the filtration of plasma AGT through the damaged glomeruli and production of AGT in the proximal tubules. However, the relative merits of the filtration and production of urinary AGT levels in chronic kidney diseases (CKD) have not been clarified. Therefore, we investigated them in CKD patients. Methods We recruited 41 biopsy-proven patients diagnosed with IgA nephropathy (IgAN) in 31, membranous nephropathy (MN) in 5, and tubulointerstitial nephritis (TIN) in 5. The patients taking RAS blockers were excluded. Results The urinary albumin levels in MN patients were significantly higher and those in TIN patients significantly lower than in IgAN patients, and the urinary AGT levels in the MN and TIN patients were significantly higher than those in IgAN patients. Conversely, the urinary AGT-to-urinary albumin (urinary AGT/Alb) ratios were the same for IgAN and MN patients, and those of TIN patients were significantly higher than those of IgAN and MN patients. A multiple linear regression analysis revealed that the urinary AGT/Alb ratios had a significant positive association with IgAN and TIN after adjustments (ß=0.75, and p<0.01). Conclusion These data suggest that the origins of urinary AGT may differ according to the etiology of renal damage [i.e. glomerular damage (such as IgAN and MN) or tubulointerstitial damage (such as TIN)], and a higher urinary AGT/Alb ratio, as in TIN, may reflect AGT production in the kidney.

Urinary angiotensinogen increases in the absence of overt renal injury in high fat diet-induced type 2 diabetic mice.

AIM OF THE STUDY: During type 2 diabetes (T2D) and hypertension there is stimulation of renal proximal tubule angiotensinogen (AGT), but whether urinary excretion of AGT (uAGT) is an indicator of glomerular damage or intrarenal RAS activation is unclear. We tested the hypothesis that elevations in uAGT can be detected in the absence of albuminuria in a mouse model of T2D. METHODS: Male C57BL/6 mice (N = 10) were fed a high fat (HFD; 45% Kcal from fat) for 28 weeks, and the metabolic phenotype including body weight, blood pressures, glucose, insulin, ippGTT, HOMA-IR, and cholesterol was examined. In addition, kidney Ang II content and reactive oxygen species (ROS) was measured along with urinary albumin, creatinine, Ang II, and AGT. RESULTS: All parameters consistent with T2D were present in mice after 12-14 weeks on the HFD. Systolic BP increased after 18 weeks in HFD but not NFD mice. Intrarenal ROS and Ang II concentrations were also increased in HFD mice. Remarkably, these changes paralleled the augmentation uAGT excretion (3.66 ±â€¯0.50 vs. 0.92 ±â€¯0.13 ng/mg by week 29; P < 0.01), which occurred in the absence of overt albuminuria. CONCLUSIONS: In HFD-induced T2D mice, increases in uAGT occur in the absence of overt renal injury, indicating that this biomarker accurately detects early intrarenal RAS activation.

The Role of Urinary Angiotensinogen in Kidney Interstitial Inflammation and Renal Prognosis.

INTRODUCTION: Urinary angiotensinogen (uAGT) has been described as a novel biomarker of acute kidney injury (AKI) and chronic kidney disease (CKD). Renal interstitial inflammatory cell infiltration is a common renal pathological feature of AKI and CKD. However, the correlation between uAGT and renal interstitial inflammatory cell infiltration is unknown. The aim of this study was to analyze the expression of uAGT, its relationship with interstitial inflammatory cell infiltration, and prognosis in patients with renal insufficiency. METHODS: The expression of uAGT, urinary kidney injury molecule 1 (uKIM-1), and urinary neutrophil gelatinase-associated lipocalin (uNGAL) were examined by enzyme-linked immunosorbent assay (ELISA) at baseline and kidney pathology was evaluated at the same time. RESULTS: Sixty-five patients with renal insufficiency and 12 healthy controls were enrolled. uAGT, uKIM-1, and uNGAL levels were significantly higher compared with healthy participants. uAGT showed the strongest correlation with interstitial inflammatory cell infiltration (r = 0.366, P < .05). uAGT level was able to identify interstitial inflammatory cell infiltration with greater accuracy (AUC = 0.664, P < .05) than other urinary biomarkers. After a median follow-up of 22 months, 15 patients reached the composite renal endpoint. Kaplan meier survival curves followed by multivariate cox proportional hazards regression analysis showed that uAGT (> 166.8 ng/mg creatinine) independently predicted higher risk of the endpoint. CONCLUSION: uAGT may be used as a non-invasive biomarker of interstitial inflammatory cell infiltration and a strong predictor of renal prognosis in patients with renal insufficiency.

Urinary angiotensinogen antedates the development of stage 3 CKD in patients with type 1 diabetes mellitus.

We examined if urinary angiotensinogen (uAOG), a marker of intrarenal renin-angiotensin system activity, antedates stage 3 chronic kidney disease (CKD) using samples from participants in the Diabetes Control and Complications Trial (DCCT) and later in the Epidemiology of Diabetes Intervention and Complications (EDIC) trial. In a nested case-control design, cases were matched at the outcome visit (eGFR less than 60, 21-59 mL/min per 1.73 m2 ) on age, gender, and diabetes duration, with controls: eGFR (95, 75-119, mL/min per 1.73 m2 .) Additionally, in an exploratory analysis progressive renal decline (PRD), defined as eGFR loss >3.5 mL/min per 1.73m2 /year, was evaluated using only data from EDIC because no progressions were observed during DCCT. At the EDIC visit, which antedated the GFR outcome visit by 2 years (range 1-7years) the median uAOG/creatinine was markedly higher in cases than in controls (13.9 vs. 3.8 ng/mg P = 0.003) whereas at the DCCT visit, which antedated the GFR outcome by 17 to 20 years it was not (2.75 vs. 3.16 ng/mg, respectively). The Odds Ratio for uAOG and CKD stage 3 development was significant after adjusting for eGFR, HbA1c, and systolic blood pressure 1.82 (1.00-3.29) but no longer significant when Albumin Excretion Ratio (AER) was included 1.21 (0.65-2.24).In the PRD analysis, uAOG/creatinine was sixfold higher in participants who experienced PRD than in those who did not (26 vs. 4.0 ng/mg, P = 0.003). The Odds Ratio for uAOG and PRD was significant after adjusting for eGFR, HbA1c, and systolic blood pressure 2.48 (1.46-4.22) but no longer significant when AER was included 1.32 (0.76-2.30). In people with type1 diabetes, a robust increase in uAOG antedates the development of stage 3 CKD but is not superior to AER in predicting this renal outcome. Increased uAOG moreover is associated with PRD, an index of progression to End Stage Kidney Disease (ESKD).