Plasma Angiotensinogen Research Articles

Association of vascular endothelial growth factor-C, plasma angiotensinogen and left ventricular hypertrophy in patients with hemodialysis.

This study aims to examine the relationship between fluid overload, Vascular Endothelial Growth Factor C (VEGF-C), plasma Angiotensinogen (pAGT), and echocardiography findings in hemodialysis patients. This was a single-center, cross-sectional study. Patients were divided into two groups according to mid-week inter-dialytic weight gain (mIDWG): (1) mIDWG ≤3% and (2) mIDW >3%. A total of 55 patients were enrolled in this study. While the mean pAGT and left ventricular mass index were significantly higher in patients with mIDWG >3% compared to patients with mIDWG ≤3%, VEGF-C was similar between groups. pAGT ≥76.8 mcg/L, VEGF-C ≤175.5 pg/ML, and pAGT /VEGF-C ≥0.45 were significant cut-offs for the prediction of left ventricular hypertrophy(LVH). Univariate logistic regression analysis revealed that these cut-off values were significantly associated with LVH. Renin-angiotensin-aldosterone system activation may persist in hemodialysis patients with excessive IDWG. Additionally, pAGT and VEGF-C could be risk factors for the development of LVH.

Enlighten the association of Angiotensinogen gene (AGT) polymorphisms and hypertension in Jammu region of north Indian population: A case-control study

BackgroundHypertension is a common cause associated with various life-threatening disorders such as stroke, heart attack, etc. AGT, with its two common polymorphisms, i.e., rs699 and rs4762, has been associated with variation in plasma angiotensinogen concentration and linked to essential hypertension. AimIn the present study, we aimed to find the association between the two polymorphisms, namely rs699 and rs4762 of the AGT gene, with the risk of hypertension in people of the Jammu region of Jammu and Kashmir. MethodTo achieve the aim, an observational with case-control study design was utilized where the descriptive and inferential data were presented in frequency, and an Odds ratio with a 95% Confidence Interval was used for determining the risk association, respectively. Online free statistical tools were used for the statistical analysis. The pairwise linkage disequilibrium (LD) and its respective measures (D′ & r(Mills et al., 2020 (Mills et al., 2020))) for the SNPs among the hypertensive patients and controls were calculated using Haploview software. ResultA total of 180 cases and 350 controls were enrolled, where “rs699” showed an increased risk (OR: 1.72 [1.28–2.31], p-value =0.0003) for hypertension in contrast to “rs4762” which showed a protective role (OR: 0.55 [0.37–0.82], p-value <0.002) in the population of Jammu. After linkage disequilibrium analysis, the risk of disease due to haplotype was also analyzed, and it was found that CC (rs699/ rs4762) significantly (p-value <0.00001) increases the risk by 1.9-fold. ConclusionThe present study concluded that “rs699” showed an increased risk for hypertension in the population of the Jammu region in contrast to “rs4762”.

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 &gt; 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.

Functional Exploration of Conserved Sequences in the Distal Face of Angiotensinogen-Brief Report.

Angiotensinogen (AGT) is an essential component in the renin-angiotensin system. AGT has highly conserved sequences in the loop and β-sheet regions among species; however, their functions have not been studied. Adeno-associated viral vector (AAV) serotype 2/8 encoding mouse AGT with mutations of conserved sequences in the loop (AAV.loop-Mut), β-sheet (AAV.βsheet-Mut), or both regions (AAV.loop/βsheet-Mut) was injected into male hepatocyte-specific AGT-deficient (hepAGT-/-) mice in an LDL (low-density lipoprotein) receptor-deficient background. AAV containing mouse wild-type AGT (AAV.mAGT) or a null vector (AAV.null) were used as controls. Two weeks after AAV administration, all mice were fed a western diet for 12 weeks. To determine how AGT secretion is regulated in hepatocytes, AAVs containing the above mutations were transducted into HepG2 cells. In hepAGT-/- mice infected with AAV.loop-Mut or βsheet-Mut, plasma AGT concentrations, systolic blood pressure, and atherosclerosis were comparable to those in AAV.mAGT-infected mice. Interestingly, plasma AGT concentrations, systolic blood pressure, and atherosclerotic lesion size in hepAGT-/- mice infected with AAV.loop/βsheet-Mut were not different from mice infected with AAV.null. In contrast, hepatic Agt mRNA abundance was elevated to a comparable magnitude as AAV.mAGT-infected mice. Immunostaining showed that AGT protein was accumulated in hepatocytes of mice infected with AAV.loop/βsheet-Mut or HepG2 cells transducted with AAV.loop/βsheet-Mut. Accumulated AGT was not located in the endoplasmic reticulum. The conserved sequences in either the loop or β-sheet region individually have no effect on AGT regulation, but the conserved sequences in both regions synergistically contribute to the secretion of AGT from hepatocytes.

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.

Antisense oligonucleotides targeting hepatic angiotensinogen reduce atherosclerosis and liver steatosis in hypercholesterolemic mice.

Hepatocyte-derived angiotensinogen (AGT) is the precursor of angiotensin II (AngII). We determined the effects of hepatocyte-specific (N-acetylgalactosamine-conjugated) antisense oligonucleotides targeting AGT (GalNAc AGT ASO) on AngII-mediated blood pressure (BP) regulation and atherosclerosis and compared its effects with losartan, an AngII type 1 (AT1) receptor blocker, in hypercholesterolemic mice. Eight-week-old male low-density lipoprotein (LDL) receptor deficient mice were administered vehicle or GalNAc AGT ASO (1, 2.5, or 5 mg/kg) subcutaneously beginning 2 weeks before the initiation of Western diet feeding. All mice were fed Western diet for 12 weeks. Their systolic BP was monitored by the tail-cuff technique, and the atherosclerotic lesion area was measured by an en face method. Although the effects of all 3 doses of GalNAc AGT ASO on plasma AGT concentrations were similar, GalNAc AGT ASO reduced BP and atherosclerotic lesion size in a dose-dependent manner. Subsequently, we compared the effects of GalNAc AGT ASO (5 mg/kg) with losartan (15 mg/kg/day). Compared to losartan, GalNAc AGT ASO led to more profound increases in plasma renin and reduction in BP but had similar effects on atherosclerosis. Remarkably, GalNAc AGT ASO also reduced liver steatosis, which was not observed in losartan-treated mice. In conclusion, the BP increase and atherosclerosis development in hypercholesterolemic mice are dependent on AngII generated from hepatic AGT. Deleting hepatic AGT improves diet-induced liver steatosis, and this occurs in an AT1 receptor-independent manner.

LRP1 protects against excessive superior mesenteric artery remodeling by modulating angiotensin II-mediated signaling.

Vascular smooth muscle cells (vSMCs) exert a critical role in sensing and maintaining vascular integrity. These cells abundantly express the low-density lipoprotein receptor-related protein 1 (LRP1), a large endocytic signaling receptor that recognizes numerous ligands, including apolipoprotein E-rich lipoproteins, proteases, and protease-inhibitor complexes. We observed the spontaneous formation of aneurysms in the superior mesenteric artery (SMA) of both male and female mice in which LRP1 was genetically deleted in vSMCs (smLRP1-/- mice). Quantitative proteomics revealed elevated abundance of several proteins in smLRP1-/- mice that are known to be induced by angiotensin II-mediated (AngII-mediated) signaling, suggesting that this pathway was dysregulated. Administration of losartan, an AngII type I receptor antagonist, or an angiotensinogen antisense oligonucleotide to reduce plasma angiotensinogen concentrations restored the normal SMA phenotype in smLRP1-/- mice and prevented aneurysm formation. Additionally, using a vascular injury model, we noted excessive vascular remodeling and neointima formation in smLRP1-/- mice that was restored by losartan administration. Together, these findings reveal that LRP1 regulates vascular integrity and remodeling of the SMA by attenuating excessive AngII-mediated signaling.

Renin-angiotensin-aldosterone system function in the pig-to-baboon kidney xenotransplantation model

After pig-to-baboon kidney transplantation, episodes of hypovolemia and hypotension from an unexplained mechanism have been reported. This study evaluated the renin-angiotensin-aldosterone system post–kidney xenotransplantation. Kidneys from genetically-engineered pigs were transplanted into 5 immunosuppressed baboons after the excision of the native kidneys. Immunosuppressive therapy was based on the blockade of the CD40/CD154 costimulation pathway. Plasma renin, angiotensinogen (AGT), angiotensin II (Ang II), aldosterone levels, and urine osmolality and electrolytes were measured in healthy pigs, healthy nonimmunosuppressed baboons, and immunosuppressed baboons with life-supporting pig kidney grafts. After pig kidney transplantation, plasma renin and Ang II levels were not significantly different, although Ang II trended lower, even though plasma AGT and potassium were increased. Plasma aldosterone levels were unchanged. Urine osmolality and sodium concentration were decreased. Even in the presence of increasing AGT and potassium levels, lower plasma Ang II concentrations may be because of reduced, albeit not absent, the reactivity of pig renin to cleave baboon AGT, suggesting an impaired response of the renin-angiotensin-aldosterone system to hypovolemic and hypotensive episodes. The maintenance of aldosterone may be protective. The reduced urine osmolality and sodium concentration reflect the decreased ability of the pig kidney to concentrate urine. These considerations should not prohibit successful clinical pig kidney xenotransplantation.

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.

Conventional Vasopressor and Vasopressor-Sparing Strategies to Counteract the Blood Pressure-Lowering Effect of Small Interfering RNA Targeting Angiotensinogen.

BackgroundA single dose of small interfering RNA (siRNA) targeting liver angiotensinogen eliminates hepatic angiotensinogen and lowers blood pressure. Angiotensinogen elimination raises concerns for clinical application because an angiotensin rise is needed to maintain perfusion pressure during hypovolemia. Here, we investigated whether conventional vasopressors can raise arterial pressure after angiotensinogen depletion.Methods and ResultsSpontaneously hypertensive rats on a low‐salt diet were treated with siRNA (10 mg/kg fortnightly) for 4 weeks, supplemented during the final 2 weeks with fludrocortisone (6 mg/kg per day), the α‐adrenergic agonist midodrine (4 mg/kg per day), or a high‐salt diet (all groups n=6–7). Pressor responsiveness to angiotensin II and norepinephrine was assessed before and after siRNA administration. Blood pressure was measured via radiotelemetry. Depletion of liver angiotensinogen by siRNA lowered plasma angiotensinogen concentrations by 99.2±0.1% and mean arterial pressure by 19 mm Hg. siRNA‐mediated blood pressure lowering was rapidly reversed by intravenous angiotensin II or norepinephrine, or gradually reversed by fludrocortisone or high salt intake. Midodrine had no effect. Unexpectedly, fludrocortisone partially restored plasma angiotensinogen concentrations in siRNA‐treated rats, and nearly abolished plasma renin concentrations. To investigate whether this angiotensinogen originated from nonhepatic sources, fludrocortisone was administered to mice lacking hepatic angiotensinogen. Fludrocortisone did not increase angiotensinogen in these mice, implying that the rise in angiotensinogen in the siRNA‐treated rats must have depended on the liver, most likely reflecting diminished cleavage by renin.ConclusionsIntact pressor responsiveness to conventional vasopressors provides pharmacological means to regulate the blood pressure–lowering effect of angiotensinogen siRNA and may support future therapeutic implementation of siRNA.

ANTISENSE OLIGONUCLEOTIDES TARGETING HEPATIC ANGIOTENSINOGEN DOSE-DEPENDENTLY REDUCE ATHEROSCLEROSIS AND LIVER STEATOSIS IN HYPERCHOLESTEROLEMIC MICE

Objective: Liver-derived angiotensinogen (AGT) is the substrate from which renin and ACE generate angiotensin (Ang) II. Ang II not only increases blood pressure, but also is a major determinant of atherosclerosis in hypercholesteremic mice. Here we investigated the effect of hepatocyte-specific (N-acetylgalactosamine-conjugated) antisense oligonucleotides targeting AGT (GalNAc AGT ASOs) on blood pressure and atherosclerosis in hypercholesterolemic mice. Design and method: Eight-week-old male LDL receptor deficient mice were fed a Western diet for 12 weeks, after receiving vehicle, GalNAc control ASO, or 1, 2.5 or 5 mg/kg of GalNAc AGT ASO on day 1, 3, 5 and 7 in the week prior the start of the diet (n = 6–10/group). Treatment was continued thereafter on a weekly basis. Systolic blood pressure (SBP) was monitored by tail cuff. After 12 weeks, mice were euthanized and plasma was collected. Plasma AGT concentration was measured by ELISA kit, and aortic atherosclerotic lesion area was measured by an en face method. Results: The 3 GalNAc AGT ASO doses decreased plasma AGT from 10.3 ± 0.8 to 1.4 ± 0.1, 0.9 ± 0.1 and 0.7 ± 0.1 g/mL, respectively. These decreases were paralleled by dose-dependent SBP reductions from 114 ± 3 to 96 ± 2, 92 ± 2, and 84 ± 2 mmHg, respectively, and atherosclerotic lesion area reductions from 27.4 ± 0.9 to 15.1 ± 1.4, 10.8 ± 1.2, and 7.7 ± 1.0%, respectively. Yet, the attenuation of liver steatosis (liver triglyceride/weight from 139.7 ± 35.7 to 26.8 ± 4.5, 19.9 ± 1.2 and 36.0 ± 3.6 g/mg, liver total cholesterol/weight from 19.8 ± 1.6 to 8.6 ± 0.9, 6.1 ± 0.6 and 8.2 ± 0.7 g/mg) was identical for each GalNAc AGT ASO dose. GalNAc control ASO did not have effects on plasma AGT, SBP, atherosclerosis lesion area, or liver steatosis vs. vehicle. Conclusions: In hypercholesterolemic mice, inhibition of hepatic AGT reduces systolic blood pressure and atherosclerosis dose-dependently, while liver steatosis was prevented in dose-independent manner.

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.

Circulating human sPRR increased blood pressure in female mice fed a low‐fat diet

Essential hypertension and obesity‐hypertension have been associated with elevated plasma soluble prorenin receptor (sPRR) in men. Additionally, our laboratory previously found that the infusion of mouse sPRR elevates systolic blood pressure (SBP) in high‐fat (HF) fed male mice through activation of the sympathetic nervous system but did not elevate SBP in HF‐fed female mice. Interestingly, the infusion of mouse sPRR increased renal and hepatic angiotensinogen (AGT) and plasma renin concentration in female mice fed a standard diet. However, the mechanistic role of sPRR on the renin angiotensin system (RAS) to regulate blood pressure in lean female mice remains to be investigated. Moreover, there is critical gap concerning the functional role of human sPRR on blood pressure in women. Therefore, in the present study, we aim to determine whether human sPRR participates to blood pressure control in lean female mice.A transgenic mouse model expressing the human form of the soluble prorenin receptor (HsPRR‐Myc‐tag) was developed. Human sPRR‐transgenic female mice were bred with male mice expressing Alb/Cre recombinase to generate mice selectively expressing human sPRR (Alb‐HsPRR) in the liver and control littermates (CTL). Control and Alb‐HsPRR female mice were fed a LF‐diet for 8 months (n=11/groups). Body weight was assessed weekly and body composition was examined monthly. Blood pressure was assessed by radiotelemetry. Human sPRR‐Myc‐tag was detected in the liver of Alb‐HsPRR female mice and plasma sPRR levels increased by 50‐fold (CTL: 3.6±0.5 ng/ml, Alb‐HsPRR: 190.5±24.4 ng/ml; P&lt;0.05), which validated the humanized mouse model.Elevated circulating human sPRR did not change body weight (CTL: 22.2±0.4g, Alb‐HsPRR: 23.0±0.3g) or fat mass (CTL: 2.5±0.2, Alb‐HsPRR:3.1±0.2g). Liver‐derived human sPRR significantly elevated SBP in Alb‐HsPRR compared to control female mice (Night SBP: CTL, 130.5±1.2 mmHg; Alb‐HsPRR, 135.9±2 mmHg; P&lt;0.05) and acute injection of Angiotensin II exacerbated the SBP elevation. Interestingly, the decrease in blood pressure mediated by Losartan was not different between Alb‐HsPRR and control female mice (Night □SBP: CTL, ‐13.1±2.2 mmHg; Alb‐HsPRR, ‐14.8±2.7 mmHg; P&gt;0.05). Plasma AGT and renin activity were similar between Alb‐HsPRR and control littermate female mice suggesting that the elevation of SBP was not mediated by the circulating renin angiotensin system. Therefore, whether the sympathetic nervous system is involved in human sPRR‐mediated increase of SBP remains to be examined. Altogether, these results support an important role of circulating human sPRR in blood pressure control in women.

Abstract 543: Inhibition Of Renin-angiotensin System Failed To Suppress Beta-aminopropionitrile-induced Thoracic Aortopathies In Mice

Objective: Cross-linking of elastin and collagen fibers is a vital process in aortic development. Pharmacological inhibition of aortic cross-linking by β-aminopropionitrile (BAPN) leads to thoracic aortopathies, such as thoracic aortic aneurysm and dissection, in mice. Although the renin angiotensin system (RAS) contributes to several types of thoracic aortopathies, it remains unclear whether inhibition of the RAS protects against aortopathy formation caused by the impairment of elastin and collagen cross-linking in mice. Approach and Results: Either vehicle or losartan (15 mg/kg/d, AT1 receptor blocker) were administered through osmotic pumps for 4 weeks in male C57BL/6J mice (3-4-weeks-old, n=30/group). BAPN (0.5% wt/vol) was given through drinking water to induce aortopathies. Losartan increased plasma renin concentrations significantly compared to vehicle-infused mice, indicating effective blockade of at1 receptors. However, losartan did not suppress BAPN-induced aortic rupture and dilatation. Since losartan is a surmountable inhibitor, we also tested the effects of irbesartan, an insurmountable inhibitor of AT1 receptor blocker, on BAPN-induced aortopathy formation (50 mg/kg/day, diet, n=30/group). Despite the significant increase of plasma renin concentrations, irbesartan did not ameliorate aortic rupture and dilatation in BAPN-administered mice. Thus, BAPN-induced thoracic aortopathies were refractory to angiotensin receptor blockade. We next inhibited angiotensinogen, the unique substrate for angiotensin II, using an antisense oligonucleotide targeting angiotensinogen (AGT-ASO). AGT-ASO decreased plasma angiotensinogen concentrations, while aortic death and dilatations were not attenuated. Since hepatocytes are the major source of angiotensinogen, BAPN-induced thoracic aortopathy formation was also examined in mice with hepatocyte-specific angiotensinogen deletion. Although plasma angiotensinogen concentrations displayed 90% reduction compared to wild type littermates, aortic rupture and aneurysm formation were not suppressed. Conclusion: Inhibition of the RAS does not attenuate BAPN-induced thoracic aortopathy formation in mice.

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

Abstract 47: Circulating Human Sprr Increased Blood Pressure In Female Mice Fed A Low-fat Diet

Elevated plasma soluble prorenin receptor (sPRR) is associated with essential hypertension and obesity-hypertension in men. Additionally, our laboratory previously found that the infusion of mouse sPRR elevates systolic blood pressure (SBP) in high-fat (HF) fed male mice through activation of the sympathetic nervous system but did not elevate SBP in HF-fed female mice. Interestingly, mouse sPRR infusion increased renal and hepatic angiotensinogen (AGT) and plasma renin concentration in female mice fed a low-fat diet. However, whether sPRR-activates the renin angiotensin system (RAS) and increases blood pressure in low-fat fed female mice remains to be investigated. Additionally, little is known concerning the influence of human sPRR on blood pressure in women. Therefore, we developed a humanized mouse model with high circulating human sPRR. Human sPRR-Myc-tag transgenic mice were bred with mice expressing Alb/Cre recombinase to induce human sPRR release in the circulation. Control and Alb-HsPRR female mice were fed a LF-diet for 8 months (n=11/groups). Body weight and body composition were examined and blood pressure assessed by radiotelemetry. Human sPRR-Myc-tag was detected in the liver of Alb-HsPRR female mice and plasma sPRR levels increased by 50-fold (CTL: 3.6±0.5 ng/ml, HsPRR:190.5±24.4 ng/ml; P&lt;0.05), which validated the humanized mouse model. Elevated circulating human sPRR did not change body weight (CTL: 22.2±0.37, HsPRR: 23.0±0.32 g) or fat mass (CTL: 2.5±0.2, HsPRR: 3.1±0.2 g). Liver-derived human sPRR significantly elevated SBP in Alb-HsPRR compared to control female mice (Night SBP: CTL: 130.5±1.2 mmHg; Alb-HsPRR: 135.9±2 mmHg; P&lt;0.05) and acute injection of AngII exacerbated SBP elevation. Interestingly, the decrease in blood pressure mediated by losartan was not different between Alb-HsPRR and control female mice (Night ΔSBP: CTL: -13.11±2.2 mmHg; Alb-HsPRR: -14.8±2.7 mmHg; P&gt;0.05). Plasma AGT and renin activity were similar between Alb-HsPRR and control female mice. Therefore, whether the local RAS or the sympathetic nervous system are involved in human sPRR-mediated increase of SBP remains to be examined. Altogether, our results suggest an important role of circulating human sPRR in blood pressure control in women.