Ang II-induced Hypertension Research Articles

Targeting GPR39 in structure-based drug discovery reduces Ang II-induced hypertension.

The endothelium-dependent vascular injury, a primary pathological feature of angiotensin II (Ang II)-induced hypertension. This study aimed to explore the role and underlying mechanisms of G protein-coupled receptor 39 (GPR39) in the pathogenesis of Ang II-induced hypertension. For in vivo studies, GPR39 knockout (KO) mice (C57BL/6 J, male) were generated and administered Ang II for 4 weeks. GPR39 expression was upregulated in the aorta of hypertensive patients and mice. The ablation of GPR39 mitigated vascular fibrosis, augmented endothelium-dependent vasodilation, and inhibited endothelial inflammation, oxidative stress, and apoptosis in mice. Additionally, GPR39 KO decreased NOD-like receptor protein 3 (Nlrp3) gene expression in Ang II-stimulated endothelial cells. Notably, Nlrp3 activation counteracted the therapeutic benefits of GPR39 KO. We identified the potential ligand of GPR39 using structure-based high throughput virtual screening (HTVS) and validated its antihypertensive function in vitro and in vivo. The small molecule ligand Z1780628919 of GPR39 can also reduce Ang II-induced hypertension and improve vascular function. GPR39 KO and the small molecule ligand Z1780628919 potentially downregulates Nlrp3, thereby mitigating vascular fibrosis, endothelial inflammation, oxidative stress, and apoptosis. This effect contributes to the alleviation of Ang II-induced hypertension and the rectification of vascular dysfunctions. These findings suggest new avenues for therapeutic intervention.

Dendritic cell mineralocorticoid receptor controls blood pressure by regulating T helper 17 differentiation: role of the Plcβ1/4-Stat5-NF-κB pathway.

Dendritic cells (DCs) are closely related to blood pressure (BP) regulation. Mineralocorticoid receptor (MR) is an important drug target for antihypertensive treatment. However, the role of DC MR in the pathogenesis of hypertension has not been fully elucidated. This study aimed to determine the role of DC MR in BP regulation and to explore the mechanism. Renal biopsy and peripheral blood samples were collected from hypertensive patients (HTN) for immunostaining and flow cytometry. Dendritic cell MR knockout (DCMRKO) mice, DC MR overexpressing (DCMROV) mice, DCMROV/IL-17A knockout (DCMROV/IL-17AKO) mice and finerenone-treated C57BL/6 mice were infused with angiotensin II (Ang II) to establish hypertensive models. Western blotting, chromatin immunoprecipitation, co-immunoprecipitation, and in vivo DC depletion or adoptive transfer were used to delineate the functional importance of DC MR in hypertension development. Mineralocorticoid receptor antagonists (spironolactone and finerenone) suppressed DC aggregation and activation, as well as hypertension in HTN and mice. Compared with littermate control (LC) mice, dendritic cell MR knockout mice had strikingly decreased BPs and attenuated target organ damage after Ang II infusion. Flow cytometry showed that DC MR deficiency mitigated Ang II-induced DC activation and T helper 17 (Th17) cell differentiation. RNA sequencing revealed that MR-deficient DCs had elevated expression of Plcβ1 and Plcβ4, knockdown of which reversed the inhibitory effect of MR deficiency on DC activation and Th17 differentiation. Adoptive transfer of MR-deficient DCs protected Ang II-induced hypertension, whereas knockdown of Plcβ1/4 eliminated the protective effects. At the molecular level, MR negatively regulated Plcβ1/4, which recruited SHP-1 to inactivate of Stat5 activity, resulting in enhanced NF-κB activation and Th17 polarization. Furthermore, DCMROV mice manifested more elevated BPs and target organ damage than control mice after Ang II infusion, and these differences were abolished in DCMROV/IL-17AKO mice. Finally, MR antagonists decreased the aggregation of Th17 in HTN and mice. Dendritic cell MR plays important roles in the pathogenesis of hypertension by regulating Th17 through Plcβ1/4-Stat5-NF-κB signalling, and blockade of DC MR is beneficial for treating hypertension.

Conditional over-expression of heme-oxygenase 1 in myelomonocytic cells reduces AngII-induced hypertension and vascular inflammation in mice

Abstract Background Systemic arterial Hypertension is one of the most important risk factor responsible for morbidity and mortality world-wide. Angiotensin II (Ang II), a potent vasoconstrictor and key player in the renin-angiotensin-aldosterone system (RAAS) is responsible for vascular dysfunction, inflammation, and tissue damage. Heme oxygenase-1 (HO-1) overexpression may confer antioxidant and anti-inflammatory properties in Ang II-induced hypertension through its action on heme catabolism, generating carbon monoxide (CO), ferritin and biliverdin/bilirubin by the action of biliverdin reductase A (BLVRA). Methods and results Male 9–12-weeks-old HO-1indxLySMCre/wt and LySMCre/wt mice were infused with AngII (1mgAngII/Day/Kg) for 7 days to induce hypertension and compared to sham treatment. Blood pressure monitoring by tail-cuff method, and endothelium-dependent vasodilator studies via organ chamber system using acetylcholine (ACh) in isolated aortic segments (~4 mm), revealed that overexpression of HO-1 in myeloid cells resulted in decreased systolic blood pressure and improved endothelial function in AngII-infused HO-1indxLySMCre/wt mice compared to controls. Concurrently, increased BLVRA expression in liver tissue and elevated plasma bilirubin levels were detected by transcriptome analysis and high-performance liquid chromatography, respectively. These results were supported by a reduction in the expression of inducible cytokines and cell adhesion molecules (CAMs) in the aorta, assessed using qPCR. Bone marrow transplant experiments demonstrated that bone marrow from LysMcre mice in HO-1indxLySMCre/wt mice abrogated the protective effect of HO-1, resulting in endothelial damage and increased blood pressure, potentially due to decreased liver BLVRA expression and the accumulation of bone marrow-derived cells in the vessel wall in response to AngII. Additionally, adeno-associated viral vector (AAV) transfection targeting specifically BLVRA activity in liver lead to an increase in blood pressure values and worse endothelium relaxation, in parallel with higher oxidative stress and the blood neutrophils concentration, as assessed in whole blood by using oxidative burst method and blood count system respectively. Conclusion The overexpression of HO-1 in myeloid cells confers anti-inflammatory protection in AngII-induced arterial hypertension in mice. Myeloid cells bone marrow-derived overexpressing HO-1 regulate the differentiation and infiltration of pro-inflammatory immune cells in the vasculature. BLVRA expression and bilirubin levels downstream of HO-1 play a critical role in protecting against vascular damage by reducing leukocyte infiltration.

α-Mangostin Attenuates Blood Pressure and Reverses Vascular Remodeling by Balancing ACE/AT1R and ACE2/Ang-(1-7)/MasR Axes in Ang II-Infused Hypertensive Mice.

Hyperuricemia is a common comorbidity of hypertension and probably has a causal relationship with hypertension. Alpha-mangostin (α-MG) has been reported to have uric acid lowering effect. This study aimed to investigate the dual effects of α-MG on blood pressure (BP) and uric acid levels in angiotensin II (Ang II)-infused hypertensive mice. Male C57BL/6 mice were randomized into five groups: control, Ang II infusion (500 ng/kg/min for 2 weeks), Ang II infusion with gavage administration of α-MG 4.0 and 8.0 mg/kg and benzbromarone (25 mg/kg) respectively. BP, uric acid levels, vascular structure and function, and renin-Ang II system expressions in the aorta were assessed. Treatment with α-MG reduced BP, improved endothelial relaxation, and reversed aortic wall thickening and collagen deposition in Ang II-induced hypertensive mice. It also downregulated Ang II receptor 1 (AT1R) and angiotensin converting enzyme (ACE) expression, while upregulating ACE2, Mas receptor (MasR), and angiotensin (1-7) in the aorta. Moreover, α-MG demonstrated a significant enhancement in uric acid clearance and reduction in serum uric acid levels. Conversely, benzbromarone did not result in a decrease in BP, indicating that the hypotensive effect of α-MG may not be necessarily dependent on its urate-lowering properties. α-MG can attenuate Ang II-induced hypertension and reverse vascular remodeling, potentially by balancing the ACE/Ang II/AT1R axis and the ACE2/Ang-(1-7)/MasR axis. Our findings provide insights into α-MG as a novel anti-hypertensive drug especially in patients with hyperuricemia.

Hypertension disrupts the vascular clock in both sexes.

Blood pressure (BP) displays a circadian rhythm and disruptions in this pattern elevate cardiovascular risk. Although both central and peripheral clock genes are implicated in these processes, the importance of vascular clock genes is not fully understood. BP, vascular reactivity, and the renin-angiotensin-aldosterone system display overt sex differences, but whether changes in circadian patterns underlie these differences is unknown. Therefore, we hypothesized that circadian rhythms and vascular clock genes would differ across sex and would be blunted by angiotensin II (ANG II)-induced hypertension. ANG II infusion elevated BP and disrupted circadian patterns similarly in both males and females. In females, an impact on heart rate (HR) and locomotor activity was revealed, whereas in males hypertension suppressed baroreflex sensitivity (BRS). A marked disruption in the vascular expression patterns of period circadian regulator 1 (Per1) and brain and muscle aryl hydrocarbon receptor nuclear translocator like protein 1 (Bmal1) was noted in both sexes. Vascular expression of the G protein-coupled estrogen receptor (Gper1) also showed diurnal synchronization in both sexes that was similar to that of Per1 and Per2 and disrupted by hypertension. In contrast, vascular expression of estrogen receptor 1 (Esr1) showed a diurnal rhythm and hypertension-induced disruption only in females. This study shows a strikingly similar impact of hypertension on BP rhythmicity, vascular clock genes, and vascular estrogen receptor expression in both sexes. We identified a greater impact of hypertension on locomotor activity and heart rate in females and on baroreflex sensitivity in males and also revealed a diurnal regulation of vascular estrogen receptors. These insights highlight the intricate ties between circadian biology, sex differences, and cardiovascular regulation.NEW & NOTEWORTHY This study reveals that ANG II-induced hypertension disrupts the circadian rhythm of blood pressure in both male and female mice, with parallel effects on vascular clock gene and estrogen receptor diurnal patterns. Notably, sex-specific responses to hypertension in terms of locomotor activity, heart rate, and baroreflex sensitivity are revealed. These findings pave the way for chronotherapeutic strategies tailored to mitigate cardiovascular risks associated with disrupted circadian rhythms in hypertension.

Abstract P171: 2-Methoxyestradiol By Inhibiting Central Action of 12S-Hydroxyeicosatetraenoic Acid Protects Ovariectomized Mice From Hypertension

Previously, we reported that 17β-estradiol (E2)- cytochrome P450 (CYP) 1B1-generated metabolite 2-methoxyestradiol (2-ME) in the paraventricular nucleus (PVN) protects from angiotensin (Ang) II-induced hypertension. Recently, we showed that intracerebroventricular (ICV) administration of 12(S)-hydroxyeicosatetraenoic acid (12S-HETE), an arachidonic acid-12/15-lipoxygenase (LO) metabolite produces a greater increase in blood pressure (BP) in ovariectomized (OVX) than intact LO knockout (KO) mice. These observations led to the hypothesis that 2-ME protects from Ang II-induced hypertension by inhibiting the production and action of 12S-HETE in the brain in female mice. ICV 2-ME (1.5 µg/2 µL/ alternate day) but not its vehicle (20% w/v hydroxypropyl-β-cyclodextrin) minimized the effect of Ang II (700 ng/kg/min, subcutaneous, osmotic pump, two weeks) to increase mean arterial blood pressure (MAP: Day 0 vs Day 12; 105±3 to 121±2 vs 105±3 to 153±8, mmHg) measured by radiotelemetry, urinary norepinephrine level (ELISA, 445±27 vs 898±20, ng/mL), lo mRNA expression (RT-PCR, 1.5±0 vs 2.0±1, arbitrary unit), 12S-HETE level (ELISA, 136±26 vs 285±44, pg/mg protein), and GFAP+ (immunostaining, astrocyte marker, 35±3 vs 67±3, number of cells per PVN section) cells in PVN and kidney fibrosis (histochemical-staining, 4.0±0.3 vs 9.8±0.7, arbitrary unit) in OVX-LOKO mice transduced with ICV-adenovirus-LO-DNA (1.28X10 11 pfu/ml, 2 µL, single injection) that have 12S-HETE in the brain (PVN) but not in plasma (n=4/group; P<0.05). ICV siRNA (0.4 nM, 2 µL, single injection) against 12S-HETE receptors LTB4 and GPR31 minimized Ang II-induced increased systolic BP measured by tail-cuff in intact CYP1B1 KO mice that have E2 but lacks 2-ME (mmHg, control: 108±3 to 175±6, siRNA-LTB4r2: 110±5 to 141±3, siRNA-GPR31: 114±1 to 145±2; n=8 per group). Moreover, the actions of ICV 12S-HETE (50 ng/2 µL every 3rd day) to enhance the effect of Ang II-induced increase in MAP were also minimized by ICV siRNA-LTB4 and GPR31 respectively in OXV-LOKO mice (mmHg, control: 102±2 to 168±1, siRNA-LTB4r2: 101±2 to 122±6, siRNA-GPR31: 101±3 to 129±3; n=4 per group). These data suggest that E2-CYP1B1 metabolite 2-ME, by inhibiting the production and action of 12S-HETE in the brain via LTB4r2 and GPR31 receptors protect from Ang II-induced hypertension in female mice. Thus, 2-ME and/or 12S-HETE receptor blockers could be useful for treating hypertension and its pathogenesis in females with ovarian failure.

Abstract P358: Interaction of Cytochrome P450 (CYP) 4A10 and CYP1B1 in the Paraventricular Nucleus in the Angiotensin II-induced Hypertension and Neuroinflammation in Female Mice

We have shown that 17β-estradiol (E2)-cytochrome P450 (CYP) 1B1 and catechol-ο-methyltrasnferase-generated metabolite 2-methoxyestradiol (2-ME) in the paraventricular nucleus (PVN) protects against angiotensin (Ang) II-induced hypertension and neuroinflammation. This study was conducted to determine the relationship between CYP4A10 that is expressed in the PVN and metabolizes arachidonic acid (AA) into prohypertensive eicosanoid, 20-hydroxyeicosatetraenoic acid (20-HETE), and CYP1B1 in Ang II-induced hypertension, neuroinflammation, and reactive oxygen species (ROS) production in female mice. Systemic Ang II infusion (700 ng/kg/min, s.c., two weeks) and transduction in the PVN with adenovirus (Ad)-GFP scrambled (Scr)-short hairpin (sh) RNA (200 nL bilaterally, 6.4×10 11 pfu/mL, single injection) produced a significant increase in systolic blood pressure (SBP, tail-cuff) at Day 12 compared to Day 0 (mmHg, 114±3 vs 151±3 respectively, P<0.05, n=6/group) in wild-type (WT) and a much larger increase in CYP1B1 knockout (KO) female mice having E2 but not 2-ME (119±4 vs 173±6 respectively, P<0.05, n=5/group). Ad-GFP-CYP4A10 shRNA (200 nL bilaterally, 1.0×10 12 pfu/mL, single injection) but not Ad-GFP Scr-shRNA transduced in the PVN diminished Ang II-induced increase in SBP at Day 12 in WT mice (mmHg, 119±2 vs 122±3 respectively, P<0.05, n=5/group), and CYP1B1KO mice (mmHg, 115±1 vs 133±2 respectively, P<0.05, n=5/group). Similar results were obtained with Ad-GFP-CYP4A10 shRNA compared to Ad-GFP Scr-shRNA transduced in the PVN on mean arterial pressure (MAP) measured by radiotelemetry (Day 12: mmHg, 121±4 vs 152±4 respectively, P<0.05, n=4/group) in CYP1B1 KO mice. The number of TMEM119 + microglia and GFAP + astrocytes, markers of neuroinflammation determined by immunofluorescence, and ROS production by dihydroethidium staining followed the changes in blood pressure produced by Ang II in the above groups. To determine the contribution of central AA-CYP4A10-generated 20-HETE to Ang II-induced hypertension, the effect of 20-HETE receptor GPR75 siRNA administered intracerebroventricularly (Dharmacon, SMARTpool: 0.4 nmol 2 μ l, single injection ) was examined in CYP1B1KO mice. GPR75 siRNA but not its non-target siRNA minimized Ang II-induced increase in SBP (Day 12: mmHg, 132±4 vs 171±3, P<0.05, n=6/group). These data suggest that the 20-HETE receptor antagonist could be useful in treating hypertension and associated neuroinflammation in females with ovarian dysfunction.

Abstract MP18: Evidence for An Important Physiological Role of Bradykinin B 2 Receptors in The Renomedullary Interstitial cells of The Kidney in Angiotensin II-induced Hypertension in Mice

Bradykinin is a potent vasoactive peptide of the kallikrein-kinin system and activates two different classes of G protein-coupled receptors, B 1 and B 2 , in the kidney. In the present study, we tested the hypothesis that deletion of B 2 receptors selectively in renomemdullary interstitial cells (RMICs) of the kidney medulla lowers basal blood pressure and attenuates angiotensin II (Ang II)-induced hypertension. To test the hypothesis, we generated a novel mouse model with deletion of B 2 receptors selectively in RMICs of the medulla (RMIC- Bdkrb2 -/- ) using inducible Tenascin-C-CreER2/Bdkrb2 fl/fl recombination approach. Mice with deletion of B 2 receptors selectively in RMICs developed and grew normally without structural abnormalities in the kidney medulla. Basal telemetry systolic (SBP), diastolic, and mean arterial blood pressure were significantly lower in RMIC- Bdkrb2 -/- than WT mice (WT: 123 ± 3 mmHg vs. RMIC- Bdkrb2 -/- : 106 ± 3 mmHg, P <0.01) (n=12-15). The hypotensive phenotype in RMIC- Bdkrb2 -/- mice was associated with significant decreases in 24 h urine output (WT: 1.86 ± 0.15 mL/24 h vs. RMIC- Bdkrb2 -/- : 1.09 ± 0.15 mL/24 h, P <0.05) and urine osmolality (WT: 1893 ± 441 mOsm/Kg H 2 O vs. RMIC- Bdkrb2 -/- : 1311 ± 78 mOsm/Kg H 2 O, P <0.01) (n=12=15). Deletion of Bdkrb2 receptors in RMICs significantly decreases COX-2, eNOS, ENaC, and AQP2 mRNA expression ( P <0.01 vs. WT), but not PGE 2 or prorenin receptor mRNA expression in the kidney medulla (n.s.) (n=6-10). In response to Ang II, SBP increased to 166 ± 6 mmHg in WT mice ( P <0.01 vs. Basal), but it increased only to 139 ± 5 mmHg in RMIC- Bdkrb2 -/- mice ( P <0.01 vs. WT+Ang II) (n=10-12). Ang II-induced hypertension was completely blocked by oral administration of AT 1 receptor blocker losartan (20 mg/kg/day, p.o.) in WT and RMIC- Bdkrb2 -/- mice (n=10). By comparison, infusion of DDAVP (1-deamino-8-D-arginine vasopressin, ~0.5 mg/kg/day, i.p., for 2 weeks) had no effect on blood pressure in WT and RMIC- Bdkrb2 -/- mice (n.s.) (n=8). Similarly, infusion of Ang II or DDAVP for 2 weeks significantly increased urine osmolality in WT mice ( P <0.01), and restored urine osmolality in RMIC- Bdkrb2 -/- mice to the WT basal level (1995 ± 315 mOsm/Kg H 2 O, P <0.01) (n=8-12). In conclusion, the present study demonstrates for the 1 st time that bradykinin B 2 receptors in RMICs of the kidney medulla plays an important role in maintaining basal blood pressure and urine osmolality homeostasis and the development of Ang II-induced hypertension.

Abstract P431: Crosstalk Between Dopamine Receptors and AT1R in Hypertension Induced Cardiac Remodeling

Dopamine receptors are implicated in the regulation of cardiovascular function, yet their specific roles in the modulation of hypertension and cardiac remodeling are not fully understood. The angiotensin II type 1 receptor (AT1R) plays a critical role in the pathophysiology of hypertension by mediating vasoconstriction, sodium retention, and sympathetic nervous system activation. Previous studies from our lab have demonstrated that in Ang II-induced hypertension, there are alterations in D1R and D3R expression in the left ventricle (LV) compared to wild-type (WT) mice. Evidence indicates that AT1R and D1R form heterodimers and inhibition of AT1R has been shown to enhance D1R signaling in proximal tubules, suggesting a significant interaction between these receptor systems. However, the role of intracardiac dopamine receptors on AT1R expression during hypertension remains understudied. Therefore, this study aims to elucidate the crosstalk between intracardiac dopamine receptors and AT1R in the context of hypertension and cardiac remodeling by using in vitro and in vivo pharmacological and molecular methods combined with novel genetic models. Using global D3R deficient (D3KO) and WT mice, we observed that D3KO leads to alterations in AT1R gene expression in LV compared to WT hearts (p<0.001) and in isolated LV cardiac fibroblasts (p<0.0001). D3KO and WT mouse cardiac fibroblasts (mCFb) and human cardiac fibroblasts (hCFb) were stimulated with Ang II (300nM) ± D1R antagonist (SCH, 10µM) or D3R antagonist (SB, 10µM). D1R antagonism significantly increased AT1R (Agtr1 gene) levels in both WT and D3KO mCFb (p<0.01), whereas D3R antagonism reduced AT1R gene expression following Ang II stimulation (p<0.01). Furthermore, these data were confirmed in hCFb. To determine crosstalk between dopamine receptors and AT1R, we used proximity ligation assay (PLA) to examine the close proximity (<40nm) of receptor-receptor expression and interaction. Our results indicate that in mCFb and hCFb, there is an increase in D1R-AT1R interactions following Ang II both with and without D1R antagonism (p<0.05), however, AT1R-D3R interactions were reduced (p<0.05). These data suggest that dopamine receptor activity significantly influences AT1R gene expression, highlighting a potential modulatory role for dopamine receptors in the regulation of AT1R during hypertension.

Abstract P189: Maternal Hyperandrogenemia Programs Hypoandrogenemia and Intrarenal Activation of Histone Deacetylase in Adult Male Offspring

Polycystic ovary syndrome ( PCOS ) is the most common endocrinopathy in young women. In-utero, children of ~80% of PCOS women in the US are exposed to maternal “hyperandrogenemia and obesity”. It remains unclear whether this exposure affects their cardiovascular ( CV ) health later in life. Using a well-characterized rat model of maternal PCOS, the hyperandrogenemic obese ( HAO ) dams, we previously showed that adult male, not female, offspring ( HAO F1 ) have enhanced blood pressure ( BP ) response to chronic angiotensin ( Ang ) II compared to sex-matched control offspring ( CON F1 ), suggesting their increased risk of later CV disease. Sex steroids have the potential to modulate epigenetics. Histone deacetylase ( HDAC ) and histone acetyltransferase ( HAT ) are markers of epigenetic modifications. HDACs have been shown to promote tumor necrosis factor ( TNF )-α expression and play a role in Ang II-induced hypertension. The present study was designed to test the hypothesis that male HAO F1 have intra-renal activation of HDAC and increased TNF-α that could play a role in their Ang II BP response. Methods: At 4 weeks ( wks ) of age, female SD rats were implanted (s.c.) with either 5α-dihydrotestosterone pellets (7.5 mg/90 d; HAO) or placebo pellets (CON) and mated at 9-12 wks. Offspring were obtained and weaned at 3 wks. Serum testosterone ( T; by LC/MS-MS), renal cortical TNF-α (Bioplex) and renal cortical nuclear HDAC and HAT activities (colorimetric assays) were measured in male offspring (1/litter, 16-24 wks, n=5-9). Results: Male HAO F1 had significantly lower serum T, higher renal cortical HDAC activity and TNF-α (430.2±124 vs 120.6±14 ng/dl, 0.97±0.1 vs 4.51±0.96 OD/min/mg protein and 423.7±47 vs 579.8±47 pg/g tissue, in male CON F1 vs male HAO F1 , respectively, p<0.05), and no change in their renal cortical HAT activity (vs male CON F1 ). Conclusion: Male offspring born to HAO dams develop hypoandrogenemia that is associated with intra-renal activation of HDAC that could be mediating their increased intra-renal inflammation (TNF-α expression) and mediating their exaggerated BP response to Ang II. Future studies will determine the causative relationship between hypoandrogenemia, HDAC activation and TNF-a and their role in the exaggerated pressor response to Ang II in those male offspring. Funding: AHA-24DIVSUP1273026 (JA), NIH-NIGMS P20GM121334 (JFR, NMS), R01HL135089 & R01AG075963 (JFR), AHA-22CDA938320 and 2024 Dean Franklin Award (NMS).

Abstract MP35: Angiotensin II-induced vascular response is enhanced by Extracellular Vesicles

Intro: The exact effects of extracellular vesicles (EVs) on renal hemodynamics and blood pressure remain to be determined. In this study, we examined the effect of EVs from hypertensive mice and humans on Angiotensin II (ANG II)-induced vascular response in an ex vivo model of isolated and perfused renal afferent arterioles (Af-Arts) and also assessed their effect on renal blood flow (RBF) and systolic blood pressure (SBP) in normotensive mice in vivo. Method: Circulating EVs were collected from mice with ANG II-induced hypertension (n=5) and hypertensive humans (n=2). Differential centrifugation (DCF) (5000G x 30min, followed by 17.000G for 30 minutes) was applied to generate an EV pellet (p20) which was subsequently run through size exclusion chromatography (SEC). EV size and concentration was determined by nanoparticle tracking analysis and spectral flow cytometry. Basic EV characterization was performed with cryo electron microscopy and western blotting of EV and non EV proteins. Following a 30-minute perfusion with EVs (p20 EV pellet (10 10 /ml) or fraction 1-3 or 4-6 of SEC (doses 1-9 7/ml )), dose-response curves to ANG II (10 -12 to 10 -6 mol/l) were measured in Af-Arts of C57BL/6 mice. Similar doses of EVs were infused into the penile vein of C57BL/6 mice and RBF and SBP were measured. As EVs might deliver AT1R we explored the final common pathway in vasoconstriction in vessels treated with EVs from hypertensive animals vs controls by performing immunoblotting of myosin light chain II S19 phosphorylation. Results: EVs deriving from ANG II-treated mice and hypertensive humans, but not those from normotensive control mice and humans, significantly enhanced the vasoconstrictor response to ANG II in Af-Arts of C57BL/6 mice. The same vasoconstrictor response was observed when Af-Arts were perfused with combined EV preps from DCF and SEC (fraction 1-3 vs fraction 1-6) from hypertensive animals. In vivo injection of EVs from ANG II-treated hypertensive mice reduced RBF and increased SBP in C57BL/6 mice compared to EVs from normotensive control mice. Immunoblotting of myosin light chain II S19 phosphorylation was inconclusive. Conclusion: These data suggest that EVs from hypertensive animals and humans directly affect ANG II response, renal hemodynamic and blood pressure regulation. Further work is needed to identify the EV effector candidate for enhanced ANG II response and possible effect on ART1 activation.

Abstract 32: Vγ6 + γδ T cells protect against angiotensin II-induced hypertension and vascular injury in male mice

Background: γδ T cells mediate angiotensin II (AngII)-induced blood pressure (BP) elevation, vascular injury and activated T cell infiltration in mesenteric vessels with adherent perivascular adipose tissue (MV/PVAT). γδ T cells expressing specific T cell receptor (TCR) variable (V) chain γ develop in several waves in the thymus and migrate to diverse tissues. We hypothesized that γδ T cells expressing specific Vγ subtypes in perivascular tissue are implicated in AngII detrimental hypertensive effects. Methods: C57BL/6J male mice were infused or not with AngII (490 ng/kg/min, SC) for 14 days. Vγ1 and Vγ2 (Vγ1/2) + , Vγ4 + , Vγ5 + , Vγ6 + , and Vγ7 + γδ T cell frequencies and T cell phenotypes were determined by flow cytometry in the spleen, descending thoracic aorta (DTAo)/PVAT, and MV/PVAT (n=7-13). Other sets of AngII-infused mice were injected with control or anti-Vγ6 (n=7-12) or Vγ4 antibodies (n=5-8). BP was determined by telemetry, mesenteric artery (MA) function and remodeling by pressurized myography, and T cell phenotypes by flow cytometry. Results: In DTAo/PVAT and MV/PVAT, respectively, 43±5% and 51%±6% of γδ T cells were Vγ6 + , and 17±2% and 23±4% Vγ4 + , whereas in the spleen, 36±2% of the γδ T cells were Vγ1/2 + , 32±1% Vγ4 + and 24±1% Vγ6 + . AngII increased the frequency of Vγ6 + γδ T cells in the spleen (0.8±0.1 vs 0.5±0.0% of CD3, P <0.001) and DTAo/PVAT (5.9±0.8 vs 3.6±0.5% of CD3, P <0.05), and tended to increase their frequency in MV/PVAT. The majority of Vγ6 + γδ T cells were activated (CD69 + ) in DTAo/PVAT (75±5%) and MV/PVAT (84±2%). Vγ6 + γδ T cell depletion caused a steeper BP elevation ( P <0.05) and worsened MA endothelial dysfunction (maximal acetylcholine relaxation response: 28±3 vs 55±8%, P <0.05) in mice infused with AngII. This was associated with increased CD69 + non-Vγ6 + γδ T cells in DTAo/PVAT (3.0±0.7 vs 0.8±0.4% of CD3, P <0.01) and MV/PVAT (15.2±2.6 vs 4.9±1.0% of CD3, P <0.01). Depletion of Vγ4 + γδ T cells in perivascular tissues, did not alter the AngII detrimental effects. Conclusions: Vγ6 + γδ T cells are the most abundant γδ T cell Vγ subtype in perivascular tissues. AngII increased Vγ6 + γδ T cells in the spleen and perivascular tissue. Vγ6 + γδ T cell depletion in AngII-infused mice induced a steeper BP elevation, worsened MA endothelial dysfunction, and activated non-Vγ6 + γδ T cells. Vg6 + γδ T cells may play a protective role in AngII-induced hypertension and vascular injury.

Abstract P389: Immunogenic Peptides Responsible for Experimental Hypertension Contribute to Systemic Lupus Erythematosus

Introduction: Hypertension and systemic lupus erythematosus (SLE) lead to modification of self-peptides by isolevuglandin (isoLG) lipid oxidation products. These self-peptides are presented by class 1 major histocompatibility complexes and drive CD8 + T cell activation. We have identified self-peptides from the sodium/glucose cotransporter2 (SGLT2); cadherin 16; Kelch domain-containing protein 7A and solute carrier family 23 that are IsoLG-adducted and cause CD8 + T cell activation in both ang II and L-NAME/high salt models of hypertension. These prime hypertension in response to low dose ang II. Hypothesis: We hypothesized that the same immunogenic peptides responsible for experimental hypertension contribute to systemic lupus erythematosus. Methods: A fluorescent probe made of recombinant IgG and the murine class 1 MHC H2-D b was loaded with either unadducted SGLT2 peptide or an isoLG-adducted SGLT2 peptide. This probe was used in flow cytometry to detect CD8 + T cells specific for this peptide antigen in 12-week-old C57Bl/6 and female B6SLE1.2.3 mice. Results: The unadducted SGLT2 probe recognized < 1% of CD8 + T cells (Figure). In contrast, ang II-infusion caused a striking increase in IsoLG-SGLT2 specific CD8 + T cells in C57Bl/6 aortas (Figure panels A and D). In C57Bl/6 very few CD8 + T cells recognizing IsoLG-SGLT2 were observed in the spleen (Panel B and E). Importantly, from 5 to 20% of CD8 + T cells in spleens of female B6SLE1.2.3 mice recognized the IsoLG-SGLT2 peptide (Figure panels C and E). Image 1. Conclusions: These findings strongly suggest that IsoLG-adducted peptides responsible for ang II-induced hypertension contribute to SLE and suggest that these conditions share similar immunogenicity.

Abstract P309: Vasodilating Effects of Macrolides: ex vivo and in vivo study

Background: Anecdotal reports showed a decrease in blood pressure (BP) values in subjects assuming macrolide antibiotics when co-administered with calcium channel blockers. Recently, in the MAPA study, in patients with primary hypertension given a single dose of macrolide a decrease in BP was observed. However, whether macrolides induce per se vasorelaxation remains unknown. Aim: To investigate if macrolides induce vasorelaxation and to identify the underlying mechanisms. Methods: The effects of 3 macrolides (roxithromycin, azithromycin, clarithromycin) were investigated in a wire myograph in aortas isolated from C57BL/6J mice, following standard protocols. Relaxation/contraction was evaluated in phenylephrine pre-contracted aorta segments exposed to different macrolide concentrations [10 -10 M to 10 -5 M]. Longer-term effects of azithromycin (50 mg/Kg/d intraperitoneally for 14 days) were investigated in vivo in a mouse model of Ang II-induced hypertension. BP was measured with the tail-cuff method; functional and structural/mechanical properties of the aorta and mesenteric arteries were evaluated with wire or pressure myograph, as appropriate. Results: After exposure to macrolides, phenylephrine pre-contracted mice aorta segments showed relaxation (maximum effect: -15-20% vs DMSO). The vasodilating effect was abolished by the removal of the endothelium, and was blunted by L-NAME. In the vivo studies treatment with azithromycin lowered BP values and prevented Ang II-induced endothelial dysfunction. Conclusions: Macrolides exert a vasodilatory action that involves endothelium-dependent NO release. In a model of Ang II-mediated hypertension, azithromycin exerted a BP-lowering effect.

Abstract P170: Angiotensin II Receptor Associated Protein Expression Within the PVN of Spontaneously Hypertensive Rats

Increased levels of circulating Angiotensin II (Ang II) have been linked to the development of neurogenic hypertension and elevated sympathetic activity, primarily through the Angiotensin II Receptor 1 (AT1R). Angiotensin II Receptor Associated Protein (ATRAP) is a transmembrane protein that regulates Ang II signaling by promoting the internalization of AT1R. Studies have demonstrated that in a model of Ang II-induced hypertension, enhancing ATRAP expression in the paraventricular nucleus of the hypothalamus (PVN) via Lentivirus infection reduced high blood pressure. However, whether ATRAP is differentially expressed in Spontaneously Hypertensive Rats (SHR) is unknown. We hypothesized that ATRAP gene and protein expression decreases during the development of hypertension in SHRs, leading to increased Ang II signaling. To test this, we used male SHRs at 4 (pre-hypertensive) and 12-weeks-old (wo, hypertensive; mean arterial pressure (MAP) 128.0±2.7 vs. 149.2±5.30 mmHg, respectively, measured by tail-cuff recording [Kent Scientific]) and age-matched normotensive Wistar rats (WIS, 92.6±3.3 vs. 123.6±4.6 mmHg, respectively). We measured ATRAP and AT1R mRNA expression in PVN samples using real-time PCR. Protein expression density of ATRAP was assessed using immunofluorescence (IF) and confocal imaging. We found no differences in ATRAP mRNA expression in the PVN between groups ( p >0.05). On the other hand, we found a significant increase in AT1R mRNA expression after hypertension is developed (WIS 12wo: 1.12 ± 0.35; vs. SHR 12wo: 4.17 ± 1.07, p =0.02). While no differences were found in ATRAP, using ATRAP/AT1R ratio as an indicator of AT1R overactivity and decrease in ratio after the development of hypertension (SHR 12wo: 0.23 ± 0.06 vs. WIS 12wo:1.05 ± 0.25) further indicate increased AngII signaling. As observed with ATRAP mRNA expression, no statistical differences were observed in ATRAP protein density within the SHR at 12wo as measured in a separate cohort of animals (MAP SHR 12wo:149.0 ± 3.7 vs. WIS 12wo:115.8 ± 4.0; p >0.05). These results suggest that the increased AngII signaling within the PVN of SHR are most likely due to increased AT1r expression rather than a differential expression of ATRAP. This work was partially funded by AHA 953524 to VCB.

Abstract 31: Deacetylation Mimetic Mutation of Mitochondrial Superoxide Dismutase Attenuates Angiotensin II-Induced Hypertension by Protecting Against Oxidative Stress

Almost one-half of adults have hypertension, and blood pressure is poorly controlled in a third of patients despite the use of multiple drugs, likely due to mechanisms that are not affected by current treatments. Hypertension is linked to oxidative stress; however, common antioxidants are ineffective. Hypertension is associated with inactivation of key intrinsic mitochondrial antioxidant, superoxide dismutase 2 (SOD2), due to hyperacetylation but the role of specific SOD2 lysine residues has not been defined. Hypertension is associated with SOD2 acetylation at Lysine 68 (Circ Res. 2020;126(4):439-452) and we suggested that deacetylation mimetic mutation of K68 to Arginine in SOD2 inhibits vascular oxidative stress and attenuates hypertension. To test this hypothesis, we have developed a new deacetylation mimic SOD2-K68R mice. We performed in vivo studies in SOD2-K68R mice using angiotensin II (AngII) model of vascular dysfunction and hypertension. AngII infusion in wild-type mice induced vascular inflammation and oxidative stress, and increased blood pressure to 160 mm Hg. SOD2-K68R mutation completely prevented increase in mitochondrial superoxide, abrogated vascular oxidative stress, preserved endothelial nitric oxide production, protected vasorelaxation, and attenuated AngII-induced hypertension. AngII and cytokines contribute to vascular oxidative stress and hypertension. Treatment of wild-type aortas with AngII and cytokines in organoid culture increased mitochondrial superoxide by 2-fold which was completely prevented in aortas isolated from SOD2-K68R mice. Interestingly, ex vivo treatment of aortas isolated from hypertensive mice with Sirtuin activator resveratrol reduces SOD2 acetylation, inhibits mitochondrial superoxide, and rescues endothelial nitric oxide. These data support the important role of SOD2-K68 acetylation in vascular oxidative stress and pathogenesis of hypertension. We conclude that strategies to reduce SOD2 acetylation may have therapeutic potential in the treatment of vascular dysfunction and hypertension.

O100 IL15RA MEDIATES BLOOD PRESSURE ELEVATION, INFLAMMATION AND VASCULAR DAMAGE IN ANGIOTENSIN II-INDUCED HYPERTENSION

Cytokines are key mediators regulating blood pressure (BP) and target organ damage in hypertension. IL15 levels increase in cardiovascular diseases, but the role of IL15 and its receptor alpha (IL15R) in hypertension and hypertension-mediated inflammation and vascular damage is still unknown. Wild-type and IL15Rα-/-mice (n=5-9) were infused with vehicle or angiotensin II (AngII, 490ng/min/kg). Recombinant IL15 was administered to WT mice (1ug, daily, 14 days) during AngII infusion. Telemetry, wire myography, luminometry, PSR staining, qPCR, immunoblotting, flow cytometry, and primary cell lines were used. Hypertensive patients have increased levels of IL15Rα in arteries, which significantly correlated with systolic (r=0.33, p=0.002), diastolic (r=0.27, p=0.02) pressure and maximal constriction to phenylephrine ex vivo (r=0.27, p=0.03). Similarly, AngII infusion significantly increased serum IL15/IL15Rα (8.8±0.7pg/ml vs 12.1±0.7pg/ml, p<0.01), IL15Rα mRNA (1±0.1 vs 1.8±0.1, p<0.01) and protein (1±0.03 vs 1.8±0.28, p<0.01) levels in the aortas. BP lowering using hydralazine and hydrochlorothiazide treatment prevented these changes in vasculature. IL15Rα was induced by pathophysiological stretch (15%) or interferon-gamma in adventitial fibroblasts, vascular smooth muscles, and endothelial cells in vitro. In contrast, AngII, other inflammatory cytokines or oxidative stress mediators have no such direct effect. Il15Rα-/- blunted AngII-induced hypertension (199±5.6mmHg vs 148±7.3mmHg, p<0.001), protected against endothelial dysfunction (p<0.01) and aortic superoxide production (59.4±7.8 vs 36.4±7.6 RLU/sec/mg) compared to wild-type mice. This was accompanied by reduced perivascular inflammation, lack of immune cell recruitment and effector and memory T cell formation. Similarly, T cell interferon-gamma and interleukin-17 production was attenuated in Il15Rα-/- hypertensive mice. In contrast, simultaneous administration of AngII and rIL15 into WT mice enhanced these outcomes. Perivascular fibrosis was observed in WT, but not Il15Rα-/- hypertensive animals (111036±19117 μm2 vs 48689±5515 μm2, p<0.01) and was in line with significantly lower mRNA of collagen and fibronectin protein levels in Il15Rα-/- aortas. IL15Rα plays a crucial role in immune activation, vascular damage, and AngII-induced hypertension. Targeting this pathway may offer potential therapeutic benefits for controlling hypertension and preventing associated vascular complications.

Lumican is Both a Novel Risk Factor and Potential Plasma Biomarker for Vascular Aging, Capable of Promoting VSMCs Senescence through Interacting with Integrin α2β1.

Vascular aging, a common pathogenesis of senile chronic diseases, significantly increases morbidity and mortality in older adults; its intricate cellular and molecular mechanisms necessitate further investigation. Lumican (LUM) and integrin α2β1(ITGα2β1) are profibrotic extracellular matrix proteins and vital cell regulatory receptors, respectively. However, their roles in vascular aging remain unclear. This study sought to elucidate the connection between LUM and vascular aging as well as the biological mechanism of LUM/ITGα2β1 in this process. Using an enzyme-linked immunosorbent assay, we discovered that plasma LUM was elevated in vascular aging individuals and was positively correlated with brachial-ankle pulse wave velocity. Additionally, immunohistochemical and western blot analyses confirmed LUM upregulation in arteries of older adults and aged mice, as well as in senescent vascular smooth cells (VSMCs). Wild-type and LUM semiknockout (Lum-/+) mice, along with primary VSMCs extracted from these mice, were exposed to angiotensin II (Ang II) to induce stress-induced senescence model. LUM semiknockout mitigated Ang Ⅱ-induced arteriosclerosis, hypertension, vascular aging and remodeling in mice. Both in vitro and in vivo studies revealed that LUM deficiency suppressed p53, p21, collagen 1 and collagen 3 upregulation and synthetic phenotype formation in VSMCs stimulated by Ang Ⅱ. Treating VSMCs with a ITGα2β1 antagonist reversed the aforementioned changes triggered by LUM proteins. Briefly, LUM functions as a potential marker and risk factor for vascular aging and promotes pathological changes by affecting ITGα2β1 in VSMCs. This study introduces a novel molecular target for the early diagnosis and treatment of vascular aging and age-related vascular diseases.

Deacetylation mimetic mutation of mitochondrial SOD2 attenuates ANG II-induced hypertension by protecting against oxidative stress and inflammation.

Almost one-half of adults have hypertension, and blood pressure is poorly controlled in a third of patients despite the use of multiple drugs, likely because of mechanisms that are not affected by current treatments. Hypertension is linked to oxidative stress; however, common antioxidants are ineffective. Hypertension is associated with inactivation of key intrinsic mitochondrial antioxidant, superoxide dismutase 2 (SOD2), due to hyperacetylation, but the role of specific SOD2 lysine residues has not been defined. Hypertension is associated with SOD2 acetylation at lysine 68, and we suggested that deacetylation mimetic mutation of K68 to arginine in SOD2 inhibits vascular oxidative stress and attenuates hypertension. To test this hypothesis, we have developed a new deacetylation mimetic SOD2-K68R mice. We performed in vivo studies in SOD2-K68R mice using angiotensin II (ANG II) model of vascular dysfunction and hypertension. ANG II infusion in wild-type mice induced vascular inflammation and oxidative stress and increased blood pressure to 160 mmHg. SOD2-K68R mutation completely prevented increase in mitochondrial superoxide, abrogated vascular oxidative stress, preserved endothelial nitric oxide production, protected vasorelaxation, and attenuated ANG II-induced hypertension. ANG II and cytokines contribute to vascular oxidative stress and hypertension. Treatment of wild-type aortas with ANG II and cytokines in organoid culture increased mitochondrial superoxide twofold, which was completely prevented in aortas isolated from SOD2-K68R mice. These data support the important role of SOD2-K68 acetylation in vascular oxidative stress and pathogenesis of hypertension. We conclude that strategies to reduce SOD2 acetylation may have therapeutic potential in the treatment of vascular dysfunction and hypertension.NEW & NOTEWORTHY Essential hypertension is associated with hyperacetylation of key mitochondrial antioxidant SOD2; however, the pathophysiological role of SOD2 acetylation has not been defined. Our animal study of angiotensin II hypertension model shows that deacetylation mimetic SOD2-K68R mutation prevents pathogenic increase in vascular mitochondrial superoxide, abrogates vascular oxidative stress, preserves endothelial nitric oxide, protects endothelial-dependent vasorelaxation, and attenuates hypertension. These data support the important role of SOD2-K68 acetylation in vascular oxidative stress and the pathogenesis of hypertension.

MiPEP31 alleviates Ang II-induced hypertension in mice by occupying Cebpα binding sites in the pri-miR-31 promoter

BackgroundPrevious studies have shown that peptides encoded by noncoding RNAs (ncRNAs) can be used as peptide drugs to alleviate diseases. We found that microRNA-31 (miR-31) is involved in the regulation of hypertension and that the peptide miPEP31, which is encoded by the primary transcript of miR-31 (pri-miR-31), can inhibit miR-31 expression. However, the role and mechanism of miPEP31 in hypertension have not been elucidated.MethodsmiPEP31 expression was determined by western blot analysis. miPEP31-deficient mice (miPEP31−/−) were used, and synthetic miPEP31 was injected into Ang II-induced hypertensive mice. Blood pressure was monitored through the tail-cuff method. Histological staining was used to evaluate renal damage. Regulatory T (Treg) cells were assessed by flow cytometry. Differentially expressed genes were analysed through RNA sequencing. The transcription factors were predicted by JASPAR. Luciferase reporter and electrophoretic mobility shift assays (EMSAs) were used to determine the effect of pri-miR-31 on the promoter activity of miPEP31. Images were taken to track the entry of miPEP31 into the cell.ResultsmiPEP31 is endogenously expressed in target organs and cells related to hypertension. miPEP31 deficiency exacerbated but exogenous miPEP31 administration mitigated the Ang II-induced systolic blood pressure (SBP) elevation, renal impairment and Treg cell decreases in the kidney. Moreover, miPEP31 deletion increased the expression of genes related to Ang II-induced renal fibrosis. miPEP31 inhibited the transcription of miR-31 and promoted Treg differentiation by occupying the Cebpα binding site. The minimal functional domain of miPEP31 was identified and shown to regulate miR-31.ConclusionmiPEP31 was identified as a potential therapeutic peptide for treating hypertension by promoting Treg cell differentiation in vivo. Mechanistically, we found that miPEP31 acted as a transcriptional repressor to specifically inhibit miR-31 transcription by competitively occupying the Cebpα binding site in the pri-miR-31 promoter. Our study highlights the significant therapeutic effect of miPEP31 on hypertension and provides novel insight into the role and mechanism of miPEPs.