Plasma Angiotensinogen Levels Research Articles

Abstract 11373: Suppression of Plasma Angiotensin II by GLP-1 in Humans is Independent of Changes in Plasma Angiotensinogen

Introduction: In humans, the natriuretic effect of GLP-1 depends on GLP-1 receptor interaction, is independent of changes in renal blood flow, renin, ANP, and aldosterone but is accompanied by suppression of angiotensin II (ANGII). The mechanism by which GLP-1 reduces ANGII independently of changes in renin is not clarified. Hypothesis: It was hypothesized that GLP-1 suppresses renin substrate, angiotensinogen, in plasma. Methods: To test this proposal, we measured arterial angiotensinogen concentration in biobanked plasma samples from healthy males during a 3-hour GLP-1 infusion that induced natriuresis (1). Samples were from a study with fixed sodium intake where eight healthy men were examined twice in random order during a 3-hour infusion of either GLP-1(1.5 pmol kg -1 min -1 ) or vehicle together with an intravenous infusion of 0.9% NaCl (750 mL/hour). Arterial plasma angiotensinogen was measured in plasma by dilution (1:200) and addition of excess exogenous human renin (Inst. Of Biological Standards UK). After prolonged incubation, ANGI was quantified by radioimmunoassay. Intraassay variation was 9-12%. Results: Arterial plasma angiotensinogen and renin levels decreased similarly and modestly (~15 and ~30%, respectively) after NaCl infusion during both studies whereas ANGII levels decreased significantly (~25%) only during GLP-1 infusion. Conclusions: Suppression of plasma angiotensinogen is less likely to account for GLP-1-mediated ANGII suppression in healthy young males. In perspective, GLP-1 could enhance pathways of ANGII degradation rather than inhibit its formation. 1. Asmar A et al. Extracellular fluid volume expansion uncovers a natriuretic action of GLP-1: a functional GLP-1-renal axis in man. J Clin Endocrinol Metab. 2019 Jul 1;104(7):2509-2519.

Abstract 17395: Effect of ION904, an Antisense Inhibitor of Angiotensinogen Production: Results of Phase 1 and Phase 2 Pilot Studies

Background: Drugs that inhibit the renin-angiotensin-aldosterone system (RAAS) act within the kidney and disturb tubuloglomerular feedback leading to renal dysfunction and hyperkalemia. We previously published that inhibiting angiotensinogen ( AGT ) mRNA in hepatocytes with GalNAc-modified antisense oligonucleotide (ASO)-IONIS-AGT-L Rx given subcutaneously (SC) weekly is effective in significantly reducing plasma angiotensinogen (AGT) with no on-target or off-target effects. Objective: We aimed to develop a more potent and durable ASO targeting AGT . ION904 is a GalNAc-conjugated ASO that specifically reduces hepatic AGT production with minimal activity in the kidneys. Methods: In a phase 1 study (PH1), healthy volunteers were treated with placebo saline (PBO) or ION904 SC with single ascending doses (PBO or 10-120 mg, n=56). A phase 2 (PH2) pilot study (n=48) in patients with uncontrolled hypertension (SBP > 130 - ≤ 170 mmHg) on at least 1 antihypertensive medication were randomized to PBO or 30, 60, or 90 mg of ION904 SC every 4 weeks for 3 months (3:1 randomization). The primary endpoint was plasma AGT reduction at Week 15. The study was not powered for SBP reduction. Results: ION904 resulted in a significant mean percent reduction in plasma AGT levels compared to pooled PBO at Day 15 (-12% v. -76%, PBO v. 120 mg, p ≤ 0.001) in PH1. In PH2, the mean percent reduction in AGT levels were significantly greater in the ION904 group compared to PBO at the primary endpoint, Week 15, (-6% v. -79%, PBO v. 90 mg, p=0.001). Robust median AGT reductions were observed at the primary endpoint (-5% v. -86%, PBO v. 90 mg). A larger proportion of subjects (11/26, 42%) in the ION904 group achieved ≥ 10 mmHg reductions compared to PBO (3/10, 30%) at Week 15. No signals for hyperkalemia, renal dysfunction, hypotension (on target effect) or liver dysfunction or thrombocytopenia (off target effects) were noted. No drug-related serious adverse events occurred. Conclusions: Monthly administration of ION904 demonstrated significant plasma AGT reductions with a favorable safety and tolerability profile supporting development in heart failure and hypertension.

1652-P: Suppression of Plasma Angiotensin II by GLP-1 in Humans Is Independent of Changes in Plasma Angiotensinogen

In humans, the natriuretic effect of GLP-1 depends on GLP-1 receptor interaction, is independent of changes in renal blood flow, renin, ANP, and aldosterone but is accompanied by suppression of angiotensin II (ANGII). The mechanism by which GLP-1 reduces ANGII independently of changes in renin is not clarified. It was hypothesized that GLP-1 suppresses renin substrate, angiotensinogen, in plasma. To test this proposal, we measured arterial angiotensinogen concentration in biobanked plasma samples from healthy males during a 3-hour GLP-1 infusion that induced natriuresis (1). Samples were from a study with fixed sodium intake where eight healthy men were examined twice in random order during a 3-hour infusion of either GLP-1(1.5 pmol kg-1 min-1) or vehicle together with an intravenous infusion of 0.9% NaCl (750 mL/hour). Arterial plasma angiotensinogen was measured in plasma by dilution (1:200) and addition of excess exogenous human renin (Inst. of Biological Standards UK). After prolonged incubation, ANGI was quantified by radioimmunoassay. Intraassay variation was 9-12%. Arterial plasma angiotensinogen and renin levels decreased similarly and modestly (~15 and ~30%, respectively) after NaCl infusion during both studies whereas ANGII levels decreased significantly (~25%) only during GLP-1 infusion. Suppression of plasma angiotensinogen is less likely to account for GLP-1-mediated ANGII suppression in healthy young males. In perspective, GLP-1 could enhance pathways of ANGII degradation rather than inhibit its formation. 1. Asmar A et al. Extracellular fluid volume expansion uncovers a natriuretic action of GLP-1: a functional GLP-1-renal axis in man. J Clin Endocrinol Metab. 2019 Jul 1;104(7):2509-2519. Disclosure B.L.Jensen: None. A.Asmar: Research Support; Novo Nordisk A/S.

Blood Levels of Angiotensinogen and Hypertension in the Multi-Ethnic StudyofAtherosclerosis (MESA).

Angiotensinogen is the proximal precursor of the angiotensin peptide hormones of the renin-angiotensin-aldosterone system (RAAS). Clinical trials are ongoing targeting angiotensinogen for the treatment of hypertension and heart failure. The epidemiology of angiotensinogen is not well defined, particularly its relationship to ethnicity, sex, and blood pressure (BP)/hypertension. The authors sought to determine the relationship of circulating angiotensinogen levels to ethnicity, sex, BP, incident hypertension, and prevalent hypertension in a modern sex-balanced ethnically diverse cohort. Plasma angiotensinogen levels were measured in 5,786 participants from the MESA (Multi-Ethnic Study of Atherosclerosis). Linear, logistic, and Cox proportional hazards models were utilized to examine the associations of angiotensinogen with BP, prevalent hypertension, and incident hypertension, respectively. Angiotensinogen levels were significantly higher in females than males and differed across self-reported ethnicities with the ordering (from highest to lowest): White, Black, Hispanic, and Chinese adults. Higher levels were associated with higher BP and odds of prevalent hypertension, after adjusting for other risk factors. Equivalent relative differences in angiotensinogen were associated with greater differences in BP in males vs females. In males not taking RAAS-blocking medications, a standard deviation increment in log-angiotensinogen was associated with 2.61mmHg higher systolic BP (95%CI: 1.49-3.80), while in females the same increment in angiotensinogen was associated with 0.97mmHg higher systolic BP (95%CI: 0.30-1.65). Significant differences in angiotensinogen levels are present between sexes and ethnicities. A positive association is present between levels and prevalent hypertension and BP, which differs between sexes.

Abstract 044: Stimulation Of Intrarenal Angiotensinogen Expression And The Development Of Hypertension And Kidney Injury In Angiotensin II-infused Hepatic Angiotensinogen Knockout Mice

Regulation of systemic and local angiotensinogen (AGT) levels is a key determinant of tissue angiotensin II (Ang II) levels and inappropriate AGT augmentation promotes the development of hypertension and tissue injury. Kidney and urinary AGT levels are increased in Ang II-mediated hypertension. Recent studies have demonstrated that circulating hepatocyte-derived AGT (hAGT) enters kidneys sustaining kidney and urinary AGT levels. However, roles of hAGT in blood pressure elevation and kidney injury in Ang II-mediated hypertension have not been delineated. This study tested if hAGT contributes to the development of the pathophysiological events in Ang II-infused mice. A low dose of Ang II (400 ng/kg/min) was infused to male wild type (WT) and hAGT gene knockout (KO) mice (N=9 and 13) for 4 weeks. The control group in each genotype received vehicle (Veh) infusion (N=5 and 6). Western blot confirmed non-detectable levels of hAGT in KO mice. hAGT KO markedly decreased plasma AGT levels (WT+Veh:12.2±0.6 vs. hAGT KO+Veh: 0.8±0.1 μg/ml). Ang II infusion did not elevate plasma AGT levels in either WT and hAGT KO mice. Although hAGT KO mice exhibited a lower baseline of systolic blood pressure (SBP) than WT mice, Ang II-mediated increases in SBP was not attenuated in hAGT KO mice (ΔSBP in WT+Ang II: 30.1±4.4 vs. hAGT KO+Ang II: 26.0±4.2 mmHg). Kidney AGT mRNA levels were increased by Ang II infusion to the same extent in both WT and hAGT mice (WT+Ang II: 1.30±0.04 vs. hAGT KO+Ang II: 1.34±0.06, ratio to control). Likewise, Ang II infusion increased IL-6 mRNA to the same magnitude in both WT and hAGT KO mice. Urinary AGT was sustained in hAGT KO+Veh mice (66±9%) compared to WT+Veh mice. Ang II infusion did not alter urinary AGT levels in both groups. Glomerular mesangial expansion and fibrosis by Ang II infusion were not observed. Ang II infusion developed tubulointerstitial fibrosis in renal cortex and medulla. hAGT KO prevented the fibrosis only in the medulla. These outcomes demonstrate that elevation of SBP, augmentation of intrarenal AGT and IL-6 expression, and the development of renal cortical fibrosis in Ang II-mediated hypertension do not require hAGT. In contrast, hAGT contributes to renal medullary fibrosis which may be due to the lower absolute levels of blood pressure.

The Renin‐Angiotensin System after Pig Kidney Transplantation in Baboons

Resolution of many technical and immune‐related issues have allowed long‐term survival of baboons with life‐supporting pig kidney grafts. However, episodes of hypovolemia and hypotension during the post‐transplant period occur via an unexplained mechanism. It has been reported that pig renin has low reactivity on human angiotensinogen (AGT). Because the renin‐angiotensin system (RAS) is vitally important in the regulation of extracellular fluid volume and blood pressure, we evaluated the activity of the RAS in baboon’s post‐pig kidney xenotransplantation. Kidneys from genetically‐modified pigs were transplanted into 5 baboons (6 to 10 kg) that were immunosuppressed by blockade of the CD40/CD154 costimulation pathway, after excision of the native kidneys. Plasma renin, AGT (only baboon AGT could be measured), and angiotensin II levels were measured by ELISAs in (i) healthy genetically‐modified pigs (n=3), healthy non‐immunosuppressed baboons (n=6), and (iii) immunosuppressed baboons with pig kidney grafts. Samples were collected for up to 120 days post‐transplantation. Plasma renin levels were significantly greater in healthy pigs (586±139 (SE) pg/ml) than in intact baboons (430±28 pg/ml). The plasma renin levels in baboons with pig kidney grafts were similar to values in intact baboons (367±18 pg/ml), indicating the continuing production of renin by the pig kidney grafts in absence of baboon kidneys. Plasma AGT (which reflected only baboon AGT) levels were augmented in the transplanted baboons (21±0.8 µg/ml) compared to the pre‐transplant concentrations (9.9±0.8). Plasma angiotensin II levels were 16±1.3 pg/ml in intact baboons and trended lower from pre‐transplant levels in the transplanted baboons (10±1.6 pg/ml). Lower plasma angiotensin II concentrations in baboons with pig kidney grafts, even in the presence of increasing plasma AGT levels, may be a consequence of reduced, but not absent, reactivity of pig renin to cleave baboon AGT. The reduced angiotensin II levels in the transplanted baboons suggest an impaired ability to elicit a robust response to hypovolemic and hypotensive episodes.

Racial differences in dysregulation of the renin-angiotensin-aldosterone system in patients with prurigo nodularis

BackgroundThere are limited data characterizing the association between renal disease and prurigo nodularis (PN). ObjectiveTo characterize the association and describe mechanistic disease linkages between PN and renal comorbidities. MethodsWe conducted a cross-sectional analysis of renal comorbidities in PN using TriNetX, a global health research network providing access to medical records. Epidemiological findings provided the basis for translational studies on plasma and skin biopsy samples from PN patients stratified by race. ResultsPN was associated with stages 1–5 of chronic kidney disease (CKD), end-stage renal disease, nephritic syndrome, nephrotic syndrome, glomerular disease, and tubulointerstitial disease, but the associations were significantly stronger in black patients. Compared to controls, CKD progression was faster (HR 2.88, 95% CI: 1.01–8.26) only in black PN (10-year survival: 63.5% black vs. 85.5% white). Circulating plasma angiotensinogen levels were dysregulated (P < 0.001) only in black PN patients. Cutaneous transcriptomic analysis of genes related to the renin-angiotensin-aldosterone system (RAAS) revealed considerable dysregulation in PN lesions with greater dysregulation in black patients. ConclusionsSignificant dysregulation of the cutaneous and systemic RAAS in black PN patients may explain the increased incidence and severity of renal disease.

Abstract 9401: Relationship Between Circulating Levels of Angiotensinogen and Hypertension—The Multi-Ethnic Study of Atherosclerosis

Introduction: Angiotensinogen (AGT) is a critical component of the renin-angiotensin-aldosterone system (RAAS) that regulates blood pressure (BP), volume, and electrolyte levels. While physiological effects of AGT are primarily mediated by AGT-derived peptide hormones, effects of AGT independent of these peptides have been described recently in animal models. We sought to determine the relationship between AGT levels, sex, ethnicity, and hypertension (HTN). Methods: We measured baseline plasma AGT levels using an enzyme-linked immunoassay in 5,786 Multiethnic Study of Atherosclerosis (MESA) participants, aged 45 to 84 yrs. We determined the associations between AGT levels and clinical and demographic variables, medication usage, and BP at the first exam. The relationship between prevalent HTN was then determined using adjusted models. Results: Mean AGT levels (log-transformed) were significantly higher in females than males and differed across race/ethnicities with the ordering (from highest to lowest): White, Black, Hispanic, and Chinese adults. The difference between the sexes was greatest in White adults with females having 1.44 times greater levels than males (95% CI: 1.40, 1.48), and lowest in Chinese adults. In males not taking medications targeting RAAS, one SD higher log-AGT was associated with a 2.61 mmHg higher SBP (95% CI: 1.49, 3.80), in females it was associated with 0.97 mmHg higher SBP (95% CI: 0.30, 1.65). Use of RAAS-blocking medications attenuated these associations. In risk factor-adjusted models, higher levels of AGT were associated with higher odds of prevalent HTN. Conclusions: AGT levels differ between race/ethnicities and between the sexes. Higher levels of AGT are associated with higher BP and odds of prevalent HTN. Despite lower levels in males, the association between levels and BP was greater in males. Taken together, the difference in levels and in the association with BP suggests sex-specific regulation and effects of AGT.

The Liver and Heart: How the Two Most Beloved “Babies” in the Human Body Communicate

The Liver and Heart: How the Two Most Beloved “Babies” in the Human Body Communicate

Association Between AGT M235T and Left Ventricular Mass in Vietnamese Patients Diagnosed With Essential Hypertension.

Background: Increasing left ventricular mass in hypertensive patients is an independent prognostic marker for adverse cardiovascular outcomes. Genetic factors have been shown to critically affect left ventricular mass. AGT M235T is one of the genetic polymorphisms that may influence left ventricular mass due to its pivotal role in the regulation of plasma angiotensinogen level as well as hypertension pathophysiology in Asian populations. Currently, how M235T affects left ventricular mass is not well-described in Vietnamese hypertensive patients. This study aimed to investigate the association between M235T and left ventricular mass in Vietnamese patients diagnosed with essential hypertension.Materials and Methods: AGT M235T genotyping and 2D echocardiography were performed on 187 Vietnamese subjects with essential hypertension. All the ultrasound parameters were obtained to calculate the left ventricular mass index according to the American Society of Echocardiography and the European Association of Cardiovascular Imaging 2015 guidelines. Other clinical characteristics were also recorded, including age, gender, duration of hypertension, hypertensive treatment, lifestyle, renal function, fasting plasma glucose, and lipid profile.Results: MT and TT genotypes were determined in 30 and 157 subjects, respectively. AGT M235T genotype, duration of hypertension, body mass index, and ejection fraction statistically affected the left ventricular mass index, which was significantly greater in TT compared to MT carriers after adjusting for confounding factors.Conclusion: The TT genotype of AGT M23T was associated with greater left ventricular mass in Vietnamese patients diagnosed with essential hypertension.

A pilot study of alterations in oxidized angiotensinogen and antioxidants in pre-eclamptic pregnancy

The oxidation status of angiotensinogen (AGT) may have a critical role in pre-eclampsia. We used a validated, quantitative, mass spectrometry-based method to measure the oxidized and total AGT levels in plasma of pre-eclamptic women (n = 17), normotensive-matched controls (n = 17), and healthy non-pregnant women (n = 10). Measurements of plasma glutathione peroxidase (GPx) activity and serum selenium concentrations were performed as markers of circulating antioxidant capacity. Higher proportions of oxidized AGT in plasma from pre-eclamptic women compared to matched normotensive pregnant controls (P = 0.006), whilst maintaining a similar total plasma AGT concentration were found. In the pre-eclamptic group, blood pressure were correlated with the proportion of oxidized AGT; no such correlation was seen in the normotensive pregnant women. Plasma GPx was inversely correlated with oxidized AGT, and there was an inverse association between serum selenium concentration and the proportion of oxidized AGT. This is the first time that oxidized AGT in human plasma has been linked directly to antioxidant status, providing a mechanism for the enhanced oxidative stress in pre-eclampsia. We now provide pathophysiological evidence that the conversion of the reduced form of AGT to its more active oxidized form is associated with inadequate antioxidant status and could indeed contribute to the hypertension of pre-eclampsia.

1860-P: Liver Fat and Visceral Fat Are Associated with Different Metabolic and Pathophysiologic Profiles but with Similar Relationships with Whole Body Insulin Resistance

MRI-based examinations of hepatic steatosis and body fat are becoming more familiar and useful for metabolic studies including NAFLD. MRI-estimated proton density fat fraction (MRI-PDFF) can haptic fat exactly without biopsy, enabling us to evaluate the effect of liver fat more sophisticatedly than ever. Although hepatic fat and visceral fats are both important for metabolic and cardiovascular diseases, detailed evaluation of the effect of each fat depot on various metabolic profiles have not been performed, In the present study, we evaluated the differential effect between hepatic and visceral fats on various metabolic profiles including glucose and lipid metabolism, islet cell function, insulin resistance, and inflammation. A total of 82 subjects (25 healthy volunteers and 57 patients with suspected, or proven NAFLD) who underwent MRI examinations for MRI-PDFF and visceral fat measurement. Additionally, anthropometric and laboratory studies and total body fat measurement by DXA were also performed. Other causes of chronic liver diseases, such as alcoholic, autoimmune or viral hepatitis, and other diseases, were excluded from the study. The amounts of hepatic fat and visceral fats measured by MRI showed similar significant correlations with HOMA-IR (r=0.540 vs. r=0.538, p &amp;lt;0.01, respectively) as with A1C (r=0.448 vs. r=0.495, p &amp;lt;0.01 each). However, hepatic fat showed more close association with FBS, triacylglycerol, complement factor C3, and cytokeratin 18. Visceral fat correlated more with fasting plasma insulin, glucagon and angiotensinogen levels. Total body fat measured by DXA did not show such characteristic patterns of correlations and showed only a weak or no correlation with those parameters. Thus, our results showed that both hepatic fat and visceral fat depots are important determinants of whole-body insulin resistance and glucose metabolism. Disclosure I. Park: None. K. Lee: None. D. Lee: None.

Enhanced angiotensinogen expression in neonates during kidney development

We recently demonstrated that preterm neonates have higher urinary angiotensinogen (AGT) levels than full-term neonates. Here, we tested the hypothesis that enhanced neonatal AGT expression is associated with intrarenal renin-angiotensin system (RAS) status during kidney development. We prospectively recruited neonates born at our hospital and healthy children with minor glomerular abnormalities between April 2013 and March 2017. We measured neonatal plasma and urinary AGT levels at birth and 1 year later and assessed renal AGT expression in kidney tissues from neonates and healthy children using immunohistochemical (IHC) analysis. Fifty-four neonates and eight children were enrolled. Although there were no changes in plasma AGT levels, urinary AGT levels were significantly decreased 1 year after birth. Urinary AGT levels at birth were inversely correlated with gestational age, and urinary AGT levels at birth and 1 year later were inversely correlated with estimated glomerular filtration rate 1 year after birth. IHC analysis showed that renal AGT expression in neonates was higher than that in healthy children and inversely correlated with gestational age. Enhanced AGT expression and urinary AGT excretion may reflect intrarenal RAS activation associated with kidney development in utero.

Blood pressure reduction in telmisartan-treated angiotensinogen G-217A polymorphism hypertensive patients: A pilot study

Context: The angiotensinogen (AGT) G-217A polymorphism has been proved as one factor contributing the susceptibility of hypertension, meanwhile, the effect of this polymorphism to the variability antihypertensive response remains unknown. Aims: To investigate whether the angiotensinogen (AGT) G-217A polymorphism affects the blood pressure response to telmisartan and valsartan in Indonesian hypertensive patients. Methods: The blood pressure was measured by ambulatory blood pressure monitoring (ABPM) and plasma angiotensinogen (AGT) levels of telmisartan- and valsartan-treated AGT G-217A polymorphism hypertensive patients (n=46) were analyzed using ELISA at the baseline and 4 months after treatments. Molecular docking was used to predict the interaction between C/EBPα and AGT G-217A polymorphism. Results: Daytime and 24 hours blood pressure in telmisartan-treated -217 AA/AG patients were significantly lower compared to GG genotype patients. The plasma AGT level in those who had AA/AG genotype and received telmisartan 80 mg was also slightly decreased compared to GG genotype, even these differences were failed to reach statistically significant. The docking results showed that the basic region of C/EBPα transcription factor recognized the partially homologous of its consensus sequences within -217A oligonucleotide, but not in -217G oligonucleotide. Conclusions: The blood pressure reduction responses in telmisartan-treated angiotensinogen G-217A polymorphism hypertensive patients might correlate with PPARγ agonist effects of telmisartan via C/EBPα and AGT -217A interaction.

Increased Plasma Angiotensinogen Level, BMI and Its Association with the Angiotensinogen Gene M235T Polymorphism and Essential Hypertension in Myanmar

Increased Plasma Angiotensinogen Level, BMI and Its Association with the Angiotensinogen Gene M235T Polymorphism and Essential Hypertension in Myanmar

Effect of a SGLT2 inhibitor on the systemic and intrarenal renin–angiotensin system in subtotally nephrectomized rats

We aimed to examine the effects of a sodium glucose co-transporter 2 (SGLT2) inhibitor on systemic and intrarenal renin–angiotensin system (RAS) in subtotally nephrectomized non-diabetic rats, a model of chronic kidney disease (CKD). Oral administration of the selective SGLT2 inhibitor, TA-1887 (10 mg/kg/day), for 10 weeks induced glycosuria. However, plasma renin activity, plasma angiotensinogen levels, kidney angiotensin II contents and renal injury were not significantly affected by TA-1887. These data indicate that chronic treatment with an SGLT2 inhibitor does not activate the systemic and intrarenal RAS in subjects with non-diabetic CKD.

Urinary renin-angiotensin markers in polycystic kidney disease.

In autosomal dominant polycystic kidney disease (ADPKD), activation of the renin-angiotensin aldosterone system (RAAS) may contribute to hypertension and disease progression. Although previous studies have focused on circulating RAAS components, preliminary evidence suggests that APDKD may increase urinary RAAS components. Therefore, our aim was to analyze circulating and urinary RAAS components in ADPKD. We cross-sectionally compared 60 patients with ADPKD with 57 patients with non-ADPKD chronic kidney disease (CKD). The two groups were matched by sex, estimated glomerular filtration rate (eGFR), blood pressure, and RAAS inhibitor use. Despite similar plasma levels of angiotensinogen and renin, urinary angiotensinogen and renin excretion were five- to sixfold higher in ADPKD (P < 0.001). These differences persisted when adjusting for group differences and were present regardless of RAAS inhibitor use. In multivariable analyses, ADPKD, albuminuria, and the respective plasma concentrations were independent predictors for urinary angiotensinogen and renin excretion. In ADPKD, both plasma and urinary renin correlated negatively with eGFR. Total kidney volume correlated with plasma renin and albuminuria but not with urinary renin or angiotensinogen excretions. Albuminuria correlated positively with urinary angiotensinogen and renin excretions in ADPKD and CKD. In three ADPKD patients who underwent nephrectomy, the concentrations of albumin and angiotensinogen were highest in plasma, followed by cyst fluid and urine; urinary renin concentrations were higher than cyst fluid. In conclusion, this study shows that, despite similar circulating RAAS component levels, higher urinary excretions of angiotensinogen and renin are a unique feature of ADPKD. Future studies should address the underlying mechanism and whether this may contribute to hypertension or disease progression in ADPKD.

YIA 03-05 BLOOD PRESSURE REDUCTION AND DIFFERENT C/EBPα-DNA BINDING PATTERN IN TELMISARTAN-TREATED ANGIOTENSINOGEN G-217A POLYMORPHISM HYPERTENSIVE PATIENTS

Objective: To investigate whether the angiotensinogen (AGT) G-217A polymorphism affects blood pressure response of telmisartan and valsartan in hypertensive patients. Design and Method: A total of 46 primary hypertensive patients, 23 patients received telmisartan 80 mg and 23 patients received valsartan 160 mg, were observed and followed up for 4 months. The AGT G-217A polymorphism was determined by PCR-RFLP and direct sequencing method. Blood pressure response was measured daytime (6 am – 10 pm), night-time (10 pm – 6 am), and 24 hours using twenty-four hours ambulatory blood pressure monitoring (ABPM). Plasma AGT level were performed at baseline and after 4 months of ARB therapy. The docking procedure between C/EBPα (1NWQ) and oligonucleotides containing -217G and -217A was analyzed by patchdock and firedock. The visualization of the structures were done by PyMol. Results: Significantly reduced blood pressure in both daytime and 24 hours mean systolic/diastolic blood pressure were observed in patients with -217AA/AG genotype who received telmisartan, but not valsartan, compared to those carrying GG genotype. In line with the change of blood pressure, the change of plasma AGT level in those carrying -217AA/AG were slightly lower compared to GG genotype in telmisartan-treated group, even it failed to reach stastistically significant (p = 0.17). We suggested the variability antihypertensive response in telmisartan-treated AGT G-217A polymorphism hypertensive patients might correlate with the change in AGT expression due to the PPARγ-activating property of telmisartan, that involved C/EBPα. The adenine at position -217 formed a favoured hydrogen bond with Asn292 which is important for stabilizing the C/EBPα – DNA interface. This likely influences C/EBPα activity to repress AGT expression in response to PPARγ-activated telmisartan. Conclusions: AGT G-217A polymorphism may increases the antihypertensive response of telmisartan by forming a favoured hydrogen bond with Asn292 of C/EBPα protein.

Possible role for nephron-derived angiotensinogen in angiotensin-II dependent hypertension.

The role of intranephron angiotensinogen (AGT) in blood pressure (BP) regulation is not fully understood. Previous studies showed that proximal tubule-specific overexpression of AGT increases BP, whereas proximal tubule-specific deletion of AGT did not alter BP. The latter study may not have completely eliminated nephron AGT production; in addition, BP was only assessed on a normal salt diet. To evaluate this issue in greater detail, we developed mice with inducible nephron-wide AGT deletion. Mice were generated which were hemizygous for the Pax8-rtTA and LC-1 transgenes and homozygous for loxP-flanked AGT alleles to achieve nephron-wide AGT disruption after doxycycline induction. Compared to controls, AGT knockout (KO) mice demonstrated markedly reduced renal AGT immunostaining, mRNA, and protein levels; unexpectedly AGT KO mice had reduced AGT mRNA levels in the liver along with 50% reduction in plasma AGT levels. BP was significantly lower in the AGT KO mice compared to controls fed a normal, low, or high Na(+) intake, with the highest BP reduction on a low Na(+) diet. Regardless of Na(+) intake, AGT KO mice had higher plasma renin concentration (PRC) and markedly reduced urinary AGT levels compared to controls. Following angiotensin-II (Ang-II) infusion, AGT KO mice demonstrated an attenuated hypertensive response despite similar suppression of PRC in the two groups. Taken together, these data suggest that nephron-derived AGT may be involved in Ang-II-dependent hypertension, however, a clear role for nephron-derived AGT in physiological BP regulation remains to be determined.

Nanoparticle-mediated RNA interference of angiotensinogen decreases blood pressure and improves myocardial remodeling in spontaneously hypertensive rats.

Angiotensinogen (AGT) has been shown to have a role in cardiac hypertrophy, while depletion of the AGT gene in spontaneously hypertensive rats (SHR) has not been investigated. The present study investigated the effect of AGT knockdown on cardiac hypertrophy in SHR. For this, small hairpin (sh)RNAs were intravenously injected into SHRs, using a nanoparticle‑mediated transfection system. The experimental rats were divided into the following groups: a) Blank control with water treatment only, b) negative control with biscarbamate‑crosslinked Gal‑polyethylene glycol polyethylenimine nanoparticles (GPE)/negative shRNA, c) AGT‑RNA interference (RNAi) group with GPE/AGT‑shRNA, and 4) normotensive control using Wistar‑Kyoto rats (WKY) with water treatment. Three and five days following the first injection, the levels of hepatic AGT mRNA and AGT protein as well as plasma levels of AGT were markedly decreased in the AGT‑RNAi group (P<0.05). Furthermore, a significant decrease in systolic blood pressure (SBP), left ventricular weight to body weight ratio and heart weight to body weight ratio were observed in the AGT‑RNAi group compared with those in the control groups. The depletion of AGT in SHR led to a reduction in SBP by 30±4 mmHg, which was retained for >10 days. Cardiac hypertrophy was also significantly improved in AGT‑knockdown rats. In conclusion, the present study showed that AGT‑silencing had a significant inhibitory effect on hypertension and hypertensive‑induced cardiac hypertrophy in SHRs.