CD28-expressing δ T cells are increased in perivascular adipose tissue of hypertensive mice and in subcutaneous adipose tissue of obese humans

OBJECTIVES

γδ T-lymphocytes play a role in angiotensin II (AngII)-induced hypertension, vascular injury and T-cell infiltration in perivascular adipose tissue (PVAT) in mice. Mesenteric arteries of hypertensive mice and subcutaneous arteries from obese humans present similar remodeling. We hypothesized that γδ T-cell subtypes in mesenteric vessels with PVAT (MV/PVAT) from hypertensive mice and subcutaneous adipose tissue (SAT) from obese humans, who are prone to develop hypertension, would be similar.

METHODS

Mice were infused with AngII for 14 days. MV/PVAT T-cells were used for single-cell RNA-sequencing (scRNA-seq). scRNA-seq data (GSE155960) of SAT CD45+ cells from three lean and three obese women were downloaded from the Gene Expression Omnibus database.

RESULTS

δ T-cell subclustering identified six δ T-cell subtypes. AngII increased T-cell receptor δ variable 4 (Trdv4)+ γδ T-effector memory cells and Cd28high δ TEM-cells, changes confirmed by flow cytometry. δ T-cell subclustering identified nine δ T-cell subtypes in human SAT. CD28 expressing δ T-cell subclustering demonstrated similar δ T-cell subpopulations in murine MV/PVAT and human SAT. Cd28+ γδ NKTEM and Cd28high δ TEM-cells increased in MV/PVAT from hypertensive mice and CD28high δ TEM-cells in SAT from obese women compared to the lean women.

CONCLUSION

Similar CD28+ δ T-cells were identified in murine MV/PVAT and human SAT. CD28high δ TEM-cells increased in MV/PVAT in hypertensive mice and in SAT from humans with obesity, a prehypertensive condition. CD28+ δ T-lymphocytes could have a pathogenic role in human hypertension associated with obesity, and could be a potential target for therapy.

P2RX7 gene knockout or antagonism reduces angiotensin II-induced hypertension, vascular injury and immune cell activation

OBJECTIVE

Extracellular ATP is elevated in hypertensive mice and humans and may trigger immune activation through the purinergic receptor P2X7 (P2RX7) causing interleukin-1β production and T-cell activation and memory T-cell development. Furthermore, P2RX7 single nucleotide polymorphisms (SNP) are associated with hypertension. We hypothesized that P2RX7 activation contributes to hypertension and cardiovascular injury by promoting immune activation.

METHODS

Male wild-type and P2rx7-/- mice were infused or not with angiotensin II (AngII) for 14 days. A second group of AngII-infused wild-type mice were co-infused with the P2RX7 antagonist AZ10606120 or vehicle. BP was monitored by telemetry. Cardiac and mesenteric artery function and remodeling were assessed using ultrasound and pressure myography, respectively. T cells were profiled in thoracic aorta/perivascular adipose tissue by flow cytometry. Associations between SNPs within 50 kb of P2RX7 transcription, and BP or hypertension were modeled in 384 653 UK Biobank participants.

RESULTS

P2rx7 inactivation attenuated AngII-induced SBP elevation, and mesenteric artery dysfunction and remodeling. This was associated with decreased perivascular infiltration of activated and effector memory T-cell subsets. Surprisingly, P2rx7 knockout exaggerated AngII-induced cardiac dysfunction and remodeling. Treatment with a P2RX7 antagonist reduced BP elevation, preserved mesenteric artery function and reduced activated and effector memory T cell perivascular infiltration without adversely affecting cardiac function and remodeling in AngII-infused mice. Three P2RX7 SNPs were associated with increased odds of DBP elevation.

CONCLUSION

P2RX7 may represent a target for attenuating BP elevation and associated vascular damage by decreasing immune activation.

Angiotensin II-Induced Memory γδ T Cells Sensitize Mice to a Mild Hypertensive Stimulus

BACKGROUND

Memory T cells develop during an initial hypertensive episode, sensitizing mice to develop hypertension from further mild hypertensive challenges. We hypothesized that memory γδ T cells develop after a hypertensive challenge and sensitize mice to develop hypertension in response to a subsequent mild hypertensive challenge.

METHODS

The first aim was to profile memory γδ T cells after a 14-day pressor dose angiotensin II (AngII) infusion (490 ng/kg/min, subcutaneously) in male mice. The second aim was to deplete γδ T cells during a second 14-day subpressor dose AngII challenge (140 ng/kg/min, subcutaneously) in mice pre-exposed to an initial pressor dose AngII challenge. The third aim was to transfer 2.5 × 105 live pre-activated or not γδ T cells from mice that had received a 14-day pressor dose AngII infusion or sham treatment, to naive recipient mice stimulated with a subpressor dose AngII infusion.

RESULTS

Effector memory γδ T cells increased 5.2-fold in mesenteric vessels and perivascular adipose tissue, and 1.8-fold in mesenteric lymph nodes in pressor dose AngII-infused mice compared with sham-treated mice. Mice depleted of γδ T cells had 14 mm Hg lower systolic blood pressure (SBP) elevation than control mice from day 7 to 14 of subpressor dose AngII infusion. Adoptive transfer of γδ T cells from hypertensive mice induced an 18 mm Hg higher SBP elevation compared with a subpressor dose AngII infusion vs. γδ T cells transferred from sham-treated mice.

CONCLUSIONS

Memory γδ T cells develop in response to hypertensive stimuli, and contribute to the pathogenesis of hypertension.

Determination of Interleukin-17A and Interferon-γ Production in γδ, CD4+, and CD8+ T Cells Isolated from Murine Lymphoid Organs, Perivascular Adipose Tissue, Kidney, and Lung

T cells localized to the kidneys and vasculature/perivascular adipose tissue (PVAT) play an important role in hypertension and vascular injury. CD4⁺, CD8⁺, and γδ T-cell subtypes are programmed to produce interleukin (IL)-17 or interferon-γ (IFNγ), and naïve T cells can be induced to produce IL-17 via the IL-23 receptor. Importantly, both IL-17 and IFNγ have been demonstrated to contribute to hypertension. Therefore, profiling cytokine-producing T-cell subtypes in tissues relevant to hypertension provides useful information regarding immune activation. Here, we describe a protocol to obtain single-cell suspensions from the spleen, mesenteric lymph nodes, mesenteric vessels and PVAT, lungs, and kidneys, and profile IL-17A- and IFNγ-producing T cells using flow cytometry. This protocol is different from cytokine assays such as ELISA or ELISpot in that no prior cell sorting is required, and various T-cell subsets can be identified and individually assessed for cytokine production simultaneously within an individual sample. This is advantageous as sample processing is kept to a minimum, yet many tissues and T-cell subsets can be screened for cytokine production in a single experiment. In brief, single-cell suspensions are activated in vitro with phorbol 12-myristate 13-acetate (PMA) and ionomycin, and Golgi cytokine export is inhibited with monensin. Cells are then stained for viability and extracellular marker expression. They are then fixed and permeabilized with paraformaldehyde and saponin. Finally, antibodies against IL-17 and IFNγ are incubated with the cell suspensions to report cytokine production. T-cell cytokine production and marker expression is then determined by running samples on a flow cytometer. While other groups have published methods to perform T-cell intracellular cytokine staining for flow cytometry, this protocol is the first to describe a highly reproducible method to activate, phenotype, and determine cytokine production by CD4, CD8, and γδ T cells isolated from PVAT. Additionally, this protocol can be easily modified to investigate other intracellular and extracellular markers of interest, allowing for efficient T-cell phenotyping.

Cardiac-specific deficiency of 3-hydroxy-3-methylglutaryl coenzyme A lyase in mice causes cardiomyopathy and a distinct pattern of acyl-coenzyme A-related biomarkers

Deficiency of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) lyase (HL) is an autosomal recessive inborn error of acyl-CoA metabolism affecting the last step of leucine degradation. Patients with HL deficiency (HLD) can develop a potentially fatal cardiomyopathy. We created mice with cardiomyocyte-specific HLD (HLHKO mice), inducing Cre recombinase-mediated deletion of exon 2 at two months of age. HLHKO mice survive, but develop left ventricular hypertrophy by 9 months. Also, within minutes after intraperitoneal injection of the leucine metabolite 2-ketoisocaproate (KIC), they show transient left ventricular hypocontractility and dilation. Leucine-related acyl-CoAs were elevated in HLHKO heart (e.g., HMG-CoA, 34.0 ± 4.4 nmol/g versus 0.211 ± 0.041 in controls, p < 0.001; 3-methylcrotonyl-CoA, 5.84 ± 0.69 nmol/g versus 0.282 ± 0.043, p < 0.001; isovaleryl-CoA, 1.86 ± 0.30 nmol/g versus 0.024 ± 0.014, p < 0.01), a similar pattern to that in liver of mice with hepatic HL deficiency. After KIC loading, HMG-CoA levels in HLHKO heart were higher than under basal conditions, as were the ratios of HMG-CoA/acetyl-CoA and of HMG-CoA/succinyl-CoA. In contrast to the high levels of multiple leucine-related acyl-CoAs, biomarkers in urine and plasma of HLHKO mice show isolated hyper-3-methylglutaconic aciduria (700.8 ± 48.4 mmol/mol creatinine versus 37.6 ± 2.4 in controls, p < 0.001), and elevated C5-hydroxyacylcarnitine in plasma (0.248 ± 0.014 μmol/L versus 0.048 ± 0.005 in controls, p < 0.001). Mice with liver-specific HLD were compared, and showed normal echocardiographic findings and normal acyl-CoA profiles in heart. This study of nonhepatic tissue-specific HLD outside of liver reveals organ-specific origins of diagnostic biomarkers for HLD in blood and urine and shows that mouse cardiac HL is essential for myocardial function in a cell-autonomous, organ-autonomous fashion.

Abstract P316: ANGIOTENSIN II-INDUCED LEFT VENTRICLE HYPERTROPHY AND DYSFUNCTION WERE EXAGGERATED BY P2RX7 KNOCKOUT BUT UNAFFECTED BY P2RX7 PHARMACOLOGIC BLOCKADE

Introduction: We have demonstrated that the P2X7 receptor (P2RX7), which activates immune cells via binding of extracellular adenosine triphosphate, plays a role in hypertension and vascular injury. Angiotensin (Ang) II-induced hypertension, vascular injury and perivascular infiltration of activated CD8 + T cells were attenuated by P2rx7 knockout or P2RX7 pharmacologic blockade. However, whether P2RX7 is involved in Ang II-induced cardiac dysfunction and hypertrophy remains unknown.

Hypothesis: We hypothesized that Ang II-induced left ventricular (LV) dysfunction and hypertrophy will be blunted equally by P2rx7 knockout and P2RX7 antagonism.

Methods: Ten-to-12-week-old male C57BL/6J wild-type (WT) and P2rx7 -/- mice were infused or not with Ang II (1000 ng/kg/min) for 14 days. A second group of WT mice infused with Ang II was infused with the P2RX7 antagonist AZ10606120 (694 ng/kg/min) or vehicle for 14 days. Cardiac LV function and remodeling were determined by ultrasound, and hypertrophic markers in cardiac ventricles by reverse transcription-quantitative PCR (RT-qPCR).

Results: Ang II-induced increase in LV mass/body weight (6.3±0.2 vs 4.2±0.2 mg/g, P <0.001) and decrease in fractional shortening in WT mice (32.5±3.1% vs 43.8±2.4%, P <0.05) were exaggerated in P2rx7 -/- mice (7.3±0.5 mg/g and 20.2±3.1%, P <0.05), but not in mice receiving AZ10606120 (6.2±0.4 mg/g and 28.9±3.3%). Ang II-induced atrial natriuretic peptide ( Nppa /ribosomal protein S16 [ Rps16 ], 6.8±2.3 vs 1±0.1, P <0.001) and α-skeletal actin 1 expression ( Acta1 / Rps16 , 6.3±1.3 vs 1±0.2, P <0.001) tended to be further increased in P2rx7 -/- mice ( Nppa / Rps16 : 13.5±2.4 and Acta1 / Rps16 : 11.9±2.4), but not in AZ10606120-treated mice ( Nppa / Rps16 : 5.5±0.7 and Acta1 / Rps16 : 5.6±0.8).

Conclusion: Ang II-induced LV hypertrophy and dysfunction were exaggerated by P2rx7 knockout but were not affected by P2RX7 pharmacologic blockade.

Abstract 118: P2X7 Receptor Contributes To Angiotensin II-induced Hypertension, Vascular Injury And Cd8 + T Cell Activation

Introduction: Innate and adaptive immune cells contribute to hypertension and end-organ damage. High blood pressure (BP) causes cardiovascular injury and the release of damage-associated molecule patterns such as adenosine triphosphate (ATP). ATP can bind to the purinergic receptor P2X7 (P2RX7) on innate immune cells triggering interleukin-1β release, which drives further immune activation.

Hypothesis: We hypothesized that P2rx7 knockout or P2RX7 antagonism would blunt angiotensin II (AngII)-induced BP elevation and cardiovascular injury through decreased immune activation.

Methods: Ten-to-12-week-old male C57BL/6J wild-type (WT) and P2rx7 -/- mice were infused or not with AngII (1000 ng/kg/min) for 14 days. A second group of AngII-infused WT mice was also infused with the P2RX7 antagonist AZ10606120 (694 ng/kg/min) or vehicle. BP was determined by telemetry, plasma ATP using a bioluminescence assay, mesenteric artery function using pressurized myography, cardiac left ventricle (LV) function and mass by ultrasound and activated immune T cell infiltration in aortic perivascular adipose tissue (PVAT) by flow cytometry.

Results: AngII increased plasma ATP in WT mice (4.4±1.2 vs 2.0±0.9 μM, P <0.05). AngII-induced systolic BP elevation was reduced by P2rx7 deficiency (164±3 vs 176±2 mm Hg, P <0.05) or P2RX7 antagonism (143±5 vs 170±5 mm Hg, P <0.01). AngII decreased LV fractional shortening (FS, 32.5±3.1% vs 43.8±2.4%, P <0.05) and increased LV mass/body weight (BW) in WT mice (LVmass/BW, 6.3±0.2 vs 4.2±0.2 mg/g, P <0.001), which were exaggerated in P2rx7 -/- (FS: 20.2±3.1% and LVmass/BW: 7.2±0.5 mg/g, P <0.05), but not in mice receiving AZ10606120. AngII reduced the dilatation response of mesenteric arteries to acetylcholine in WT (61±7 vs 83±4%, P <0.05), but not in P2rx7 -/- or AZ10606120-treated mice. AngII increased CD69 + CD8 + T cell infiltration in aortic PVAT of WT (60±16 vs 16±3 cells/aortic PVAT, P <0.001), but not in P2rx7 -/- or AZ10606120-treated mice.

Conclusion: P2rx7 knockout or antagonism attenuates AngII-induced BP elevation, vascular injury, and infiltration of activated CD8 + T cells into aortic PVAT. P2rx7 knockout exacerbated AngII-induced cardiac dysfunction and hypertrophy, whereas P2RX7 antagonism did not.

Abstract 070: ONE UP-REGULATED NOVEL MICRORNA AND 4 DOWN-REGULATED MRNA TARGETS WERE IDENTIFIED IN PERIPHERAL BLOOD MONONUCLEAR CELLS OF HYPERTENSIVE PATIENTS WITH METABOLIC SYNDROME

Introduction: Hypertension is associated with target organ damage such as kidney injury. The immune system plays a role in hypertension and target organ damage. Activation of T cells has been reported among peripheral blood mononuclear cells (PBMCs) of patients with HTN. MicroRNAs are crucial post-transcriptional regulators of immune cell development and function.

Hypothesis: MicroRNAs play a role in the activation of immune cells in hypertension with target organ damage in humans.

Methods: Normotensive subjects (NTN) and patients with hypertension (HTN) associated or not with at least 2 other features of the metabolic syndrome (MetS) or chronic kidney disease (CKD) were studied (n=15-16). PBMCs were isolated from blood, RNA extracted, small and total RNA sequencing (RNA-seq) using an Illumina HiSeq-2500 and data were analyzed using a systems biology approach. Differentially expressed (DE) microRNAs and mRNAs were identified with fold change (FC) >2 and >1.5, respectively, and P <0.005. DE miRNAs with RNA-seq count number (CN) >500, and predicted targets by TargetScan with CN>300 were validated by reverse transcription-quantitative PCR (RT-qPCR) in PBMCs.

Results: RNA-seq identified DE microRNAs and mRNAs in HTN (22 and 19), MetS (57 and 401) and CKD (6 and 26) compared to NTN. RT-qPCR validated a novel miRNA (miR-pl-86 [2-fold up]) and 4 predicted mRNA targets (WD repeat domain 89 [ WDR89 , 51% down], Dmx like 1 [ DMXL1 , 52% down], zinc finger protein 600 [ ZNF600 , 63% down] and NOC3 like DNA replication regulator [ NOC3L , 61% down]) in MetS vs NTN ( P <0.05). RNA-seq results were correlated with RT-qPCR data for miR-pl-86 (R 2 =0.37, P <5.5E-07, n=56) , WDR89 (R 2 =0.29, P <1.4E-05, n=57) , DMXL1 (R 2 =0.33, P <2.7E-06, n=57) , ZNF600 (R 2 =0.25, P <7.9E-05, n=57) , and NOC3L (R 2 =0.27, P <3.5E-05, n=57).

Conclusion: This study identified one up-regulated novel microRNA and 4 down-regulated mRNA targets in PBMCs of patients with HTN and MetS.

Abstract P317: ANGIOTENSIN II INFUSION CAUSED EXPANSION OF ACTIVATED ð NATURAL KILLER T CELLS IN MESENTERIC VESSEL PERIVASCULAR ADIPOSE TISSUE OF MICE

Introduction: The innate-like γδ T cells play a role in angiotensin II (AngII)-induced hypertension, vascular injury and T cell activation in perivascular adipose tissue (PVAT).

Hypothesis: We hypothesized that single cell RNA sequencing (scRNA-seq) will reveal γδ T cell subpopulations in PVAT involved in hypertension, vascular injury and T cell activation.

Methods: Male C57BL/6J mice were infused SC or not with 490 ng/kg/min AngII for 14 days (n=3). Hypertension was confirmed by tail cuff blood pressure measurement. Mesenteric vessels (MV) with PVAT were collected, lymph nodes removed, single cell suspension obtained and labeled with hashtag antibodies, T cells isolated by fluorescence-activated cell sorting, the 6 samples pooled in one tube, and scRNA libraries prepared with a Chromium Next GEM Single Cell 3’ Reagent Kit. Sequencing was done on an Illumina Novaseq 6000, and data analysed using Cell Ranger pipeline and Seurat tools. Cell subpopulations were validated by flow cytometry.

Results: ScRNA-seq yielded 5,030 cells with 137,990 reads/cell and identified 11 T cell clusters. Subclustering of T cells expressing the T cell receptor (TCR) δ constant chain revealed 3 δ natural killer T (δNKT) (δNKT0, δNKT1 and activated δNKT cells) and 3 γδ T cell subpopulations ( Trgc1 low effector memory, TCR δ variable 4 + and apoptotic γδ T cells). AngII increased >2-fold the frequency of activated δNKT cells, and decreased by 74% δNKT0 cells. Gene expression profiling revealed that activated δNKT and δNKT0 cells could be identified using unique markers, Cd28 and Sell , respectively. Flow cytometry showed that TCRδ + CD28 + Sell - T cells were increased (393±57.2 vs 227±44.4 cells/MV-PVAT) and TCRδ + CD28 - Sell + T cells decreased (21.6±4.1 vs 45.3±4.10 cells/MV-PVAT) in MV-PVAT of AngII vs sham-treated mice.

Conclusion: This study identified an activated δNKT cell subpopulation in MV-PVAT that may play a role in AngII-induced hypertension, vascular injury and T cell activation.

Abstract P239: Angiotensin II-Induced Memory Gamma Delta T Cells Sensitize Mice To A Mild Hypertensive Stimulus

Hypothesis: We hypothesize that memory γδ T cells form after a hypertensive challenge, and that they sensitize mice to develop hypertension to mild hypertensive stimuli.

Methods: Ten-12-week-old C57BL/6J mice were exposed or not to a pressor dose of angiotensin II (490 ng/kg/min, SC) for two weeks, followed by a two-week washout period, and then infused with a subpressor dose of angiotensin II (140 ng/kg/min, SC) for two weeks. Blood pressure (BP) was measured by telemetry and memory γδ T cells profiled by flow cytometry. A subset of mice was injected IP with 400 μg of anti-T cell receptor γδ-depleting or isotype control antibodies 1 day before and 6 days after the initiation of second hypertensive challenge. A final subset was injected IV with 2.5x10 5 γδ T cells isolated from hypertensive or normotensive mice, and then exposed to a subpressor dose of angiotensin II as above.

Results: Repeated hypertensive challenges yielded a higher systolic BP than one mild hypertensive stimulus (154±4 vs 120±3 mm Hg, P <0.01). Two-week pressor dose angiotensin II increased effector memory γδ T cells in mesenteric artery perivascular adipose tissue (1.25±0.37% vs. 0.24±0.12%, P<0.05) and mesenteric lymph nodes (1.49±0.03% vs 0.82±0.15%, P<0.05). γδ T cell depletion reduced systolic BP elevation from day 8 (135±5 vs 150±5 mm Hg, P <0.05) to day 13 of the second hypertensive challenge (150±5 vs 163±2 mm Hg, P <0.05). Adoptive transfer of γδ T cells isolated from hypertensive compared to normotensive mice caused a greater systolic BP elevation in response to a subpressor dose of angiotensin II (159±3 vs 142±6 mm Hg, P <0.01).

Conclusion: Memory γδ T cells develop after a hypertensive challenge and sensitize mice to mild hypertensive stimuli. Memory γδ T cells may represent a novel therapeutic target to treat hypertensive humans.

Atrial Electrical Remodeling in Mice With Cardiac‐Specific Overexpression of Angiotensin II Type 1 Receptor

Background

Elevated angiotensin II levels are thought to play an important role in atrial electrical and structural remodeling associated with atrial fibrillation. However, the mechanisms by which this remodeling occurs are still unclear. Accordingly, we explored the effects of angiotensin II on atrial remodeling using transgenic mice overexpressing angiotensin II type 1 receptor (AT1R) specifically in cardiomyocytes.

Methods and Results

Voltage‐clamp techniques, surface ECG, programmed electrical stimulations along with quantitative polymerase chain reaction, Western blot, and Picrosirius red staining were used to compare the atrial phenotype of AT1R mice and their controls at 50 days and 6 months. Atrial cell capacitance and fibrosis were increased only in AT1R mice at 6 months, indicating the presence of structural remodeling. Ca 2+ ( I CaL ) and K + currents were not altered by AT1R overexpression (AT1R at 50 days). However, I CaL density and Ca V 1.2 messenger RNA expression were reduced by structural remodeling (AT1R at 6 months). Conversely, Na + current ( I Na ) was reduced (−65%) by AT1R overexpression (AT1R at 50 days) and the presence of structural remodeling (AT1R at 6 months) yields no further effect. The reduced I Na density was not explained by lower Na V 1.5 expression but was rather associated with an increase in sarcolemmal protein kinase C alpha expression in the atria, suggesting that chronic AT1R activation reduced I Na through protein kinase C alpha activation. Furthermore, connexin 40 expression was reduced in AT1R mice at 50 days and 6 months. These changes were associated with delayed atrial conduction time, as evidenced by prolonged P‐wave duration.

Conclusions

Chronic AT1R activation leads to slower atrial conduction caused by reduced I Na density and connexin 40 expression.

Immune System and Microvascular Remodeling in Humans

Low-grade inflammatory processes and related oxidative stress may have a key role in the pathogenesis of hypertension and hypertension-mediated organ damage. Innate immune cells, such as neutrophils, dendritic cells, monocytes/macrophages, as well as unconventional T lymphocytes like γδ T cells contribute to hypertension and may trigger vascular inflammation. Adaptive immunity has been demonstrated to participate in elevation of blood pressure and in vascular and kidney injury. In particular, effector T lymphocytes (Th1, Th2, and Th17) may play a relevant role in promoting hypertension and microvascular remodeling, whereas T-regulatory lymphocytes may have a protective role. Effector cytokines produced by these immune cells lead to increased oxidative stress, endothelial dysfunction and contribute to target organ damage in hypertension. A possible role of immune cell subpopulations in the development and regression of microvascular remodeling has also been proposed in humans with hypertension. The present review summarizes the key immune mechanisms that may participate in the pathophysiology of hypertension-mediated inflammation and vascular remodeling; advances in this field may provide the basis for novel therapeutics for hypertension.

Abstract 13: P2X7 Receptor Knockout Attenuates Angiotensin II-Induced Hypertension, Vascular Injury And CD8 + T Cell Infiltration

Background: The P2X7 receptor (P2RX7) recognizes damage associated molecule patterns such as adenosine triphosphate (ATP), and triggers the activation of immune cells. Elevated plasma ATP levels have been observed in hypertensive patients, providing a potential mechanism for P2RX7 activation. Additionally, a hypomorphic polymorphism for P2X7 is correlated with a decreased risk for essential hypertension in Chinese post-menopausal women. However, it is unknown whether P2RX7 activation contributes to angiotensin (Ang) II-induced blood pressure (BP) elevation and vascular damage. We hypothesized that P2rx7 knockout would blunt Ang II-induced BP elevation, vascular injury, and infiltration of activated immune T cells into perivascular adipose tissue (PVAT).

Methods: Ten-to-12-week-old male C57BL/6J male wild-type (WT) and P2rx7 -/- mice were infused or not with Ang II (1000ng/kg/min) for 14 days. BP was determined by telemetry, mesenteric artery function and remodeling using pressurized myography, aortic stiffening by ultrasound and infiltration of activated immune T cells in aortic PVAT by flow cytometry.

Results: Ang II-infused P2rx7 -/- mice display a reduced systolic BP (164±3 vs. 176±2 mm Hg, P <0.05) and pulse pressure (37±4 vs. 53±3 mm Hg, P <0.001) in comparison to WT mice. Aortic stiffening occurred in WT mice treated with Ang II, demonstrated by an increased pulse wave velocity (7.7±0.7 vs. 5.9±0.3 m/s, P <0.05), accompanied by a 3.8-fold increased infiltration of activated CD8 + T cells in aortic PVAT (60±16 vs 16±3 cells/aortic PVAT, P <0.001), which were both absent in P2rx7 -/- mice (6.4±1.4 vs 5.5±1.1 m/s and 27±7 vs 16±3 cells/aortic PVAT). In addition, the frequency of IFN-γ producing CD8 + T cells in the spleen of Ang II-treated WT mice increased (2.6±0.2% vs 1.2±0.2%), which did not occur in P2rx7 -/- mice (1.7±0.3% vs 1.7±0.2%). Ang II-infusion induced mesenteric artery endothelial dysfunction in WT mice (61±7 vs 83±4% relaxation response to acetylcholine, P <0.05), which was absent in P2rx7 -/- mice (89±3 vs 90±3%).

Conclusion: P2rx7 knockout attenuates Ang II-induced hypertension, vascular injury, and infiltration of activated CD8 + T cells into aortic PVAT.

Abstract 12: The Role Of Memory Gamma Delta T Cells In Hypertension And Vascular Damage

Background: We recently demonstrated that γδ T cells participate in the pathogenesis of hypertension. Evidence also suggests that memory T cells may develop during an initial hypertensive episode, sensitizing mice to develop hypertension to further mild hypertensive challenges. However, whether memory γδ T cells develop and play a role in hypertension remains unknown. Our objective is to determine if memory γδ T cells sensitize mice to develop hypertension in response to a mild hypertensive challenge.

Methods: Ten-12-week-old C57BL/6J mice were exposed or not to a hypertensive challenge (490 ng/kg/min angiotensin II (Ang II), SC) for two weeks, followed by a two-week washout period, and then infused with a subpressor dose of Ang II (140 ng/kg/min Ang II, SC) for two weeks. Blood pressure was measured via telemetry and central, effector, and resident memory γδ T cells were profiled by flow cytometry.

Results: Mice exposed to the first hypertensive challenge had a higher systolic blood pressure than the sham group at the end of the subpressor hypertensive challenge (149±6 vs. 122±3 mmHg, P <0.001). After 14-days of Ang II infusion, effector memory γδ T cells increased 5.2-fold in the mesenteric artery perivascular adipose tissue (PVAT, 1.25±0.37% vs. 0.24±0.12%, P <0.05), and 1.8-fold in the mesenteric lymph nodes (mLN, 1.49±0.03% vs. 0.82±0.15%, P <0.05) compared to sham treated mice. After repeated Ang II infusion, central memory γδ T cells decreased by 57% in the aortic PVAT (6.79±1.46% vs. 15.69±2.87%, P <0.05), and by 22% in the mLN (0.18±0.01% vs. 0.23±0.01%, P <0.05) compared to control mice.

Conclusion: An initial exposure to a hypertensive stimulus sensitizes mice to develop hypertension to a subsequent subpressor hypertensive challenge and results in the development of memory γδ T cells.

Abstract MP44: A Novel And 2 Known Differentially Expressed MicroRNAs Were Identified In Peripheral Blood Mononuclear Cells Of Patients With Hypertension Associated With Metabolic Syndrome

Background: Hypertension (HTN) is associated with subclinical target organ damage including cardiac, vascular and kidney injury. The immune system plays a role in hypertension and target organ damage. Activation of T cells has been reported among peripheral blood mononuclear cells (PBMCs) of patients with HTN. MicroRNAs (miRNAs) are crucial post-transcriptional regulators of immune cells. Whether miRNAs play a role in the activation of immune cells in hypertension complicated by target organ damage in humans remains unknown. We aimed to address this question by identifying differentially expressed (DE) miRNAs and their mRNA targets in PBMCs of patients with hypertension complicated or not with metabolic syndrome (MetS) or chronic kidney disease (CKD).

Methods: Normotensive subjects and patients with hypertension (HTN) associated or not with at least 2 other features of MetS or CKD were studied (n=15-16). PBMCs were isolated from blood, RNA extracted for small and total RNA sequencing (RNA-seq) using Illumina HiSeq-2500 and data were analyzed using a systems biology approach. MiRDeep2 was used for novel miRNAs prediction, miRNA annotation and counting. TargetScan 7.07 was used to predict DE miRNA targets with weighted context score percentile >50%. DE genes miRNAs and mRNAs were identified with fold change (FC) >1.5 and P <0.005. DE miRNAs with FC>2 and mean read count number (MRCM) >500, and with predicted targets with MRCM>300 were validated by reverse transcription-quantitative PCR (RT-qPCR).

Results: DE miRNAs, mRNAs and non-coding RNAs were identified in HTN (22, 19 and 0), MetS (57, 401 and 11) and CKD (6, 26 and 2) compared to NTN. TargetScan predicted that 7 miRNAs target 3 mRNAs in NTN, 57 miRNAs target 55 mRNAs in MetS and 3 miRNAs target 2 mRNAs in CKD. DE miR-409-5p (FC: 0.54±0.10 vs 1.00±0.09, P <0.05), miR-411-5p (FC: 0.40±0.06, vs 1.00±0.11, P <0.001) and the novel miR-pl-86 (FC: 1.96±0.17 vs 1.00±0.15, P <0.05) in MetS vs NTN were validated by RT-qPCR. RNA-seq data were correlated with RT-qPCR for miR-409-5p (R 2 =0.40, P <2.4E-07, n=55), miR-411-5p (R 2 =0.55, P <1.1E-10, n=55), miR-pl-86 (R 2 =0.37, P <5.5E-07, n=56).

Conclusion: This study showed that DE miR-409-5p, miR-411-5p and miR-pl-86 may play a role in HTN associated with MetS.

Abstract MP60: Down-regulated Mir-338-3p In Subcutaneous Small Arteries Of Hypertensive Patients With Chronic Kidney Disease Targets Protein Tyrosine Phosphatase Receptor Type S And Glutathione Peroxidase 3

Background: Hypertension (HTN) causes vascular injury identified by endothelial dysfunction, vascular stiffening, and remodeling, which contributes to kidney damage leading to chronic kidney disease (CKD). MicroRNAs (miRNAs) repress/degrade target mRNAs. Their role in vascular injury in HTN remains unclear. We aimed to identify differentially expressed (DE) miRNAs in gluteal subcutaneous arteries of patients with HTN associated or not with CKD to shed light on the pathophysiological molecular mechanisms.

Methods: Normotensive subjects and patients with HTN associated or not with CKD grades 3-4 were studied (n=15-16). Small arteries were isolated from gluteal subcutaneous biopsies, RNA extracted and small and total RNA sequencing performed by Illumina HiSeq-2500. DE genes were identified with a P <0.05 and fold change (FC) >1.3. Top 3 DE miRNAs ( P <0.001, FC>2, mean read count number (MRCN) >3,000 in all groups and having predicted mRNA targets) were selected for validation by reverse transcription-quantitative PCR (RT-qPCR). The mRNA targets of the top selected miRNA were predicted by TargetScan with P <0.01, FC>1.5 and MRCN>150 and the top 9 targets were validated by RT-qPCR using gain- and loss-of-function in human aortic endothelial cells (HAECs). Gene ontology enrichment analysis (GOEA) was done in Cytoscape.

Results: DE miRNAs and mRNAs were identified uniquely associated with HTN (miRNAs: 10, mRNAs: 68), CKD (miRNAs: 68, mRNAs: 395), and in both groups (miRNAs: 2, mRNAs: 32). miR-338-3p presented the best correlation between RNA sequencing and RT-qPCR (R 2 =0.328, P <0.001) among the top 3 DE miRNAs. Two of the selected top 9 miR-338-3p predicted targets were validated in HAECs. Protein tyrosine phosphatase receptor type S ( PTPRS , FC: 0.80±0.08 vs 1.00±0.00) and glutathione peroxidase 3 ( GPX3 , FC: 0.88±0.04 vs 1.00±0.00) were down-regulated in HAECs transfected with miR-338-3p mimics ( P <0.05). GOEA showed association of GPX3 with oxidative stress detoxification ( q <0.05), and of PTPRS with the immune system, neuronal system and developmental process ( q <0.001).

Conclusion: Down-regulated miR-338-3p in gluteal subcutaneous small arteries of hypertensive patients with CKD targets PTPRS and GPX3 that may play a role in vascular injury in HTN.

Automated Detection and Diameter Estimation for Mouse Mesenteric Artery Using Semantic Segmentation

BACKGROUND

Pressurized myography is useful for the assessment of small artery structures and function. However, this procedure requires technical expertise for sample preparation and effort to choose an appropriate sized artery. In this study, we developed an automatic artery/vein differentiation and a size measurement system utilizing machine learning algorithms.

METHODS AND RESULTS

We used 654 independent mouse mesenteric artery images for model training. The model yielded an Intersection-over-Union of 0.744 ± 0.031 and a Dice coefficient of 0.881 ± 0.016. The vessel size and lumen size calculated from the predicted vessel contours demonstrated a strong linear correlation with manually determined vessel sizes (R = 0.722 ± 0.048, p < 0.001 for vessel size and R = 0.908 ± 0.027, p < 0.001 for lumen size). Last, we assessed the relation between the vessel size before and after dissection using a pressurized myography system. We observed a strong positive correlation between the wall/lumen ratio before dissection and the lumen expansion ratio (R = 0.832, p < 0.01). Using multivariate binary logistic regression, 2 models estimating whether the vessel met the size criteria (lumen size of 160-240 μm) were generated with an area under the receiver operating characteristic curve of 0.761 for the upper limit and 0.747 for the lower limit.

CONCLUSION

The U-Net-based image analysis method could streamline the experimental approach.

High Systolic Blood Pressure at Hospital Admission Is an Important Risk Factor in Models Predicting Outcome of COVID-19 Patients

BACKGROUND

The risk that coronavirus disease 2019 (COVID-19) patients develop critical illness that can be fatal depends on their age and immune status and may also be affected by comorbidities like hypertension. The goal of this study was to develop models that predict outcome using parameters collected at admission to the hospital.

METHODS AND RESULTS

This is a retrospective single-center cohort study of COVID-19 patients at the Seventh Hospital of Wuhan City, China. Forty-three demographic, clinical, and laboratory parameters collected at admission plus discharge/death status, days from COVID-19 symptoms onset, and days of hospitalization were analyzed. From 157 patients, 120 were discharged and 37 died. Pearson correlations showed that hypertension and systolic blood pressure (SBP) were associated with death and respiratory distress parameters. A penalized logistic regression model efficiently predicts the probability of death with 13 of 43 variables. A regularized Cox regression model predicts the probability of survival with 7 of above 13 variables. SBP but not hypertension was a covariate in both mortality and survival prediction models. SBP was elevated in deceased compared with discharged COVID-19 patients.

CONCLUSIONS

Using an unbiased approach, we developed models predicting outcome of COVID-19 patients based on data available at hospital admission. This can contribute to evidence-based risk prediction and appropriate decision-making at hospital triage to provide the most appropriate care and ensure the best patient outcome. High SBP, a cause of end-organ damage and an important comorbid factor, was identified as a covariate in both mortality and survival prediction models.

Endothelium-restricted endothelin-1 overexpression in type 1 diabetes worsens atherosclerosis and immune cell infiltration via NOX1

AIMS

NADPH oxidase (NOX) 1 but not NOX4-dependent oxidative stress plays a role in diabetic vascular disease, including atherosclerosis. Endothelin (ET)-1 has been implicated in diabetes-induced vascular complications. We showed that crossing mice overexpressing human ET-1 selectively in endothelium (eET-1) with apolipoprotein E knockout (Apoe-/-) mice enhanced high-fat diet-induced atherosclerosis in part by increasing oxidative stress. We tested the hypothesis that ET-1 overexpression in the endothelium would worsen atherosclerosis in type 1 diabetes through a mechanism involving NOX1 but not NOX4.

METHODS AND RESULTS

Six-week-old male Apoe-/- and eET-1/Apoe-/- mice with or without Nox1 (Nox1-/y) or Nox4 knockout (Nox4-/-) were injected intraperitoneally with either vehicle or streptozotocin (55 mg/kg/day) for 5 days to induce type 1 diabetes and were studied 14 weeks later. ET-1 overexpression increased 2.5-fold and five-fold the atherosclerotic lesion area in the aortic sinus and arch of diabetic Apoe-/- mice, respectively. Deletion of Nox1 reduced aortic arch plaque size by 60%; in contrast, Nox4 knockout increased lesion size by 1.5-fold. ET-1 overexpression decreased aortic sinus and arch plaque alpha smooth muscle cell content by ∼35% and ∼50%, respectively, which was blunted by Nox1 but not Nox4 knockout. Reactive oxygen species production was increased two-fold in aortic arch perivascular fat of diabetic eET-1/Apoe-/- and eET-1/Apoe-/-/Nox4-/- mice but not eET-1/Apoe-/-/Nox1y/- mice. ET-1 overexpression enhanced monocyte/macrophage and CD3+ T-cell infiltration ∼2.7-fold in the aortic arch perivascular fat of diabetic Apoe-/- mice. Both Nox1 and Nox4 knockout blunted CD3+ T-cell infiltration whereas only Nox1 knockout prevented the monocyte/macrophage infiltration in diabetic eET-1/Apoe-/- mice.

CONCLUSION

Endothelium ET-1 overexpression enhances the progression of atherosclerosis in type 1 diabetes, perivascular oxidative stress, and inflammation through NOX1.

Aldosterone, Inflammation, Immune System, and Hypertension

Aldosterone is a mineralocorticoid hormone that controls body fluid and electrolyte balance. Excess aldosterone is associated with cardiovascular and metabolic diseases. Inflammation plays a critical role on vascular damage promoted by aldosterone and aggravates vascular abnormalities, including endothelial dysfunction, vascular remodeling, fibrosis and oxidative stress, and other manifestations of end-organ damage that are associated with hypertension, other forms of cardiovascular disease, and diabetes mellitus and the metabolic syndrome. Over the past few years, many studies have consistently shown that aldosterone activates cells of the innate and adaptive immune systems. Macrophages and T cells accumulate in the kidneys, heart, and vasculature in response to aldosterone, and infiltration of immune cells contributes to end-organ damage in cardiovascular and metabolic diseases. Aldosterone activates various subsets of innate immune cells such as dendritic cells and monocytes/macrophages, as well as adaptive immune cells such as T lymphocytes, and, by activation of mineralocorticoid receptors stimulates proinflammatory transcription factors and the production of adhesion molecules and inflammatory cytokines and chemokines. This review will briefly highlight some of the studies on the involvement of aldosterone in activation of innate and adaptive immune cells and its impact on the cardiovascular system. Since aldosterone plays a key role in many cardiovascular and metabolic diseases, these data will open up promising perspectives for the identification of novel biomarkers and therapeutic targets for prevention and treatment of diseases associated with increased levels of aldosterone, such as arterial hypertension, obesity, the metabolic syndrome, and heart failure.

Chromosome 2 Fragment Substitutions in Dahl Salt-Sensitive Rats and RNA Sequencing Identified Enpep and Hs2st1 as Vascular Inflammatory Modulators

Chromosome 2 introgression from normotensive Brown Norway (BN) rats into hypertensive Dahl salt-sensitive (SS) background (SS-chromosome 2^BN/Mcwi; consomic S2^B) reduced blood pressure and vascular inflammation under a normal-salt diet (NSD). We hypothesized that BN chromosome 2 contains anti-inflammatory genes that could reduce blood pressure and vascular inflammation in rats fed NSD or high-salt diet (HSD). Four- to 6-week old male SS and congenic rats containing the BN chromosome 2 distal portion (SS.BN-[rs13453786-rs66377062]/Aek; S2^Ba) and middle segment (SS.BN-[rs106982173-rs65057186]/Aek; S2^Bb) were fed NSD or HSD (4% NaCl) up to age 12 to 13 weeks. Systolic blood pressure determined by telemetry was higher in SS rats fed HSD versus NSD. Systolic blood pressure was lower in both congenic rats than in SS under NSD, but similar under HSD versus SS. Reactive oxygen species generation using dihydroethidium staining, expression of vascular cell adhesion molecule-1 and monocyte chemoattractant protein-1, and immune cell infiltration by immunofluorescence demonstrated that S2^Ba rats present less inflammation under NSD and more under HSD versus SS rats. RNA sequencing and reverse transcription-quantitative PCR identified 2 differentially expressed genes encoded within BN chromosome 2 distal portion that could act as regulators of vascular inflammation. These were downregulated glutamyl aminopeptidase (Enpep) that was anti-inflammatory under NSD and upregulated heparan sulfate 2-O-sulfotransferase 1 (Hs2st1) that was proinflammatory under HSD. In conclusion, 2 differentially expressed genes encoded within introgressed BN chromosome 2 distal fragment were identified: Enpep associated with reduced vascular inflammation under NSD, and Hs2st1, associated with increased vascular inflammation under HSD.

P2X7 Receptors: An Untapped Target for the Management of Cardiovascular Disease

Chronic low-grade inflammation contributes to the development of several diseases, including cardiovascular disease. Adequate strategies to target inflammation in cardiovascular disease are in their infancy and remain an avenue of great interest. The purinergic receptor P2X7 is a ubiquitously expressed receptor that predominately mediates inflammation and cellular death. P2X7 is a ligand-gated cation channel that is activated in response to high concentrations of extracellular ATP, triggering the assembly and activation of the NLRP3 (nuclear oligomerization domain like receptor family pyrin domain containing 3) inflammasome and subsequent release of proinflammatory cytokines IL (interleukin)-1β and IL-18. Increased P2X7 activation and IL-1β and IL-18 concentrations have been implicated in the development of many cardiovascular conditions including hypertension, atherosclerosis, ischemia/reperfusion injury, and heart failure. P2X7 receptor KO (knockout) mice exhibit a significant attenuation of the inflammatory response, which corresponds with reduced disease severity. P2X7 antagonism blunts blood pressure elevation in hypertension and progression of atherosclerosis in animal models. IL-1β and IL-18 inhibition has shown efficacy in clinical trials reducing major adverse cardiac events, including myocardial infarction, and heart failure. With several P2X7 antagonists available with proven safety margins, P2X7 antagonism could represent an untapped potential for therapeutic intervention in cardiovascular disorders.

Human and murine memory γδ T cells: Evidence for acquired immune memory in bacterial and viral infections and autoimmunity

γδ T cells are unconventional lymphocytes that could play a role in bridging the innate and adaptive immune system. Upon initial exposure to an antigen, some activated T cells become memory T cells that could be reactivated upon secondary immune challenge. Recently, subsets of γδ T cells with a restricted antigen repertoire and long-term persistence have been observed after clearance of viral and bacterial infections. These γδ T cells possess the hallmark ability of memory T cells to respond more strongly and proliferate to a higher extent upon secondary infection. Murine and primate models of Listeria monocytogenes and cytomegalovirus infection display these memory hallmarks and demonstrate γδ T cell memory responses. In addition, human and non-human primate infections with Mycobacterium tuberculosis, as well as non-human primate infection with monkeypox and studies on patients suffering from autoimmune disease (rheumatoid arthritis and multiple sclerosis) reveal memory-like responses corresponding with disease. Murine models of psoriatic disease (imiquimod) and parasite infections (malaria) exhibited shifts to memory phenotypes with repeated immune challenge. These studies provide strong support for the formation of immune memory in γδ T cells, and memory γδ T cells may have a widespread role in protective immunity and autoimmunity.

Role of interleukin-23/interleukin-17 axis in T-cell-mediated actions in hypertension

Current knowledge suggests that hypertension is in part mediated by immune mechanisms. Both interleukin (IL)-23 and IL-17 are up-regulated in several experimental hypertensive rodent models, as well as in hypertensive humans in observational studies. Recent preclinical studies have shown that either IL-23 or IL-17A treatment induce blood pressure elevation. However, the IL-23/IL-17 axis has not been a major therapeutic target in hypertension, unlike in other autoimmune diseases. In this review, we summarize current knowledge on the role of these cytokines in immune mechanisms contributing to hypertension, and discuss the potential of IL-23/IL-17-targeted therapy for treatment of hypertension.

Circulating let-7g-5p and miR-191-5p Are Independent Predictors of Chronic Kidney Disease in Hypertensive Patients

BACKGROUND

Hypertension (HTN) is associated with target organ damage such as cardiac, vascular, and kidney injury. Several studies have investigated circulating microRNAs (miRNAs) as biomarkers of cardiovascular disease, but few have examined them as biomarker of target organ damage in HTN. We aimed to identify circulating miRNAs that could serve as biomarkers of HTN-induced target organ damage using an unbiased approach.

METHODS AND RESULTS

Fifteen normotensive subjects, 16 patients with HTN, 15 with HTN associated with other features of the metabolic syndrome (MetS), and 16 with HTN or chronic kidney disease (CKD) were studied. Circulating RNA extracted from platelet-poor plasma was used for small RNA sequencing. Differentially expressed (DE) genes were identified with a threshold of false discovery rate <0.1. DE miRNAs were identified uniquely associated with HTN, MetS, or CKD. However, only 2 downregulated DE miRNAs (let-7g-5p and miR-191-5p) could be validated by reverse transcription-quantitative PCR. Let-7g-5p was associated with large vessel stiffening, miR-191-5p with MetS, and both miRNAs with estimated glomerular filtration rate (eGFR) and neutrophil and lymphocyte fraction or number and neutrophil-to-lymphocyte ratio. Using the whole population, stepwise multiple linear regression generated a model showing that let-7g-5p, miR-191-5p, and urinary albumin/creatinine ratio predicted eGFR with an adjusted R2 of 0.46 (P = 8.5e-7).

CONCLUSIONS

We identified decreased circulating let-7g-5p and miR-191-5p as independent biomarkers of CKD among patients with HTN, which could have pathophysiological and therapeutic implications.

CD4+ Regulatory T Lymphocytes Prevent Impaired Cerebral Blood Flow in Angiotensin II-Induced Hypertension

Background

Immune cells are key regulators of the vascular inflammatory response characteristic of hypertension. In hypertensive rodents, regulatory T lymphocytes (Treg, CD4⁺CD25⁺) prevented vascular injury, cardiac damage, and endothelial dysfunction of mesenteric arteries. Whether Treg modulate the cerebrovascular damage induced by hypertension is unknown.

Methods and Results

C57BL/6 mice were perfused with angiotensin II (Ang II; 1000 ng/kg per minute) for 14 days and adoptive transfer of 3×10⁵CD4⁺CD25⁺ T cells was performed via 2 intravenous injections. Control mice received a sham surgery and PBS. Treg prevented Ang II‐induced neurovascular uncoupling (P<0.05) and endothelial impairment (P<0.05), evaluated by laser Doppler flowmetry in the somatosensory cortex. The neuroprotective effect of Treg was abolished when they were isolated from mice deficient in interleukin‐10. Administration of interleukin‐10 (60 ng/d) to hypertensive mice prevented Ang II‐induced neurovascular uncoupling (P<0.05). Treg adoptive transfer also diminished systemic inflammation induced by Ang II (P<0.05), examined with a peripheral blood cytokine array. Mice receiving Ang II + Treg exhibited reduced numbers of Iba‐1+ cells in the brain cortex (P<0.05) and hippocampus (P<0.001) compared with mice infused only with Ang II. Treg prevented the increase in cerebral superoxide radicals. Overall, these effects did not appear to be directly modulated by Treg accumulating in the brain parenchyma, because only a nonsignificant number of Treg were detected in brain. Instead, Treg penetrated peripheral tissues such as the kidney, inguinal lymph nodes, and the spleen.

Conclusions

Treg prevent impaired cerebrovascular responses in Ang II‐induced hypertension. The neuroprotective effects of Treg involve the modulation of inflammation in the brain and periphery.

miR-431-5p Knockdown Protects Against Angiotensin II-Induced Hypertension and Vascular Injury

Vascular injury is an early manifestation in hypertension and a cause of end-organ damage. MicroRNAs play an important role in cardiovascular disease, but their implication in vascular injury in hypertension remains unclear. This study revealed using an unbiased approach, microRNA and mRNA sequencing with molecular interaction analysis, a microRNA-transcription factor coregulatory network involved in vascular injury in mice made hypertensive by 14-day Ang II (angiotensin II) infusion. A candidate gene approach identified upregulated miR-431-5p encoded in the conserved 12qF1 (14q32 in humans) microRNA cluster, whose expression correlated with blood pressure, and which has been shown to be upregulated in human atherosclerosis, as a potential key regulator in Ang II-induced vascular injury. Gain- and loss-of-function in human vascular smooth muscle cells demonstrated that miR-431-5p regulates in part gene expression by targeting ETS homologous factor. In vivo miR-431-5p knockdown delayed Ang II-induced blood pressure elevation and reduced vascular injury in mice, which demonstrated its potential as a target for treatment of hypertension and vascular injury.

Chronic Elevation of Endothelin-1 Alone May Not Be Sufficient to Impair Endothelium-Dependent Relaxation

Endothelin-1 (ET-1) is a powerful vasoconstrictor peptide considered to be causally implicated in hypertension and the development of cardiovascular disease. Increased ET-1 is commonly associated with reduced NO bioavailability and impaired vascular function; however, whether chronic elevation of ET-1 directly impairs endothelium-dependent relaxation (EDR) remains elusive. Herein, we report that (1) prolonged ET-1 exposure (ie, 48 hours) of naive mouse aortas or cultured endothelial cells did not impair EDR or reduce eNOS (endothelial NO synthase) activity, respectively (P>0.05); (2) mice with endothelial cell-specific ET-1 overexpression did not exhibit impaired EDR or reduced eNOS activity (P>0.05); (3) chronic (8 weeks) pharmacological blockade of ET-1 receptors in obese/hyperlipidemic mice did not improve aortic EDR or increase eNOS activity (P>0.05); and (4) vascular and plasma ET-1 did not inversely correlate with EDR in resistance arteries isolated from human subjects with a wide range of ET-1 levels (r=0.0037 and r=-0.1258, respectively). Furthermore, we report that prolonged ET-1 exposure downregulated vascular UCP-1 (uncoupling protein-1; P<0.05), which may contribute to the preservation of EDR in conditions characterized by hyperendothelinemia. Collectively, our findings demonstrate that chronic elevation of ET-1 alone may not be sufficient to impair EDR.

Abstract 008: Aldosterone Contributes to the Blood Pressure Elevation, Endothelial Dysfunction, and Norepinephrine Sensitivity Caused by Endothelial Human Endothelin-1 Overexpression in Mice

Background: The mechanisms of blood pressure (BP) regulation by endothelin (ET)-1 produced by endothelial cells (ECs) are complex and remain unclear. Transgenic mice with tamoxifen-inducible EC-restricted human ET-1 overexpression (ieET-1) exhibited BP elevation 3 months after induction. ET-1 has been shown to stimulate the release of aldosterone from adrenal cortex (AC). Whether aldosterone plays a role in EC ET-1 overexpression-induced BP elevation and vascular injury is still unknown.

Methods and results: Nine to 12-week-old male ieET-1 mice and control ieCre mice expressing a tamoxifen-inducible Cre recombinase under the control of EC-specific Tie2 promoter were treated with tamoxifen (1 mg/kg/day, SC) for 5 days and studied 3 months later. Plasma aldosterone levels measured by ELISA was increased in ieET-1 vs. ieCre mice (1.21±0.14 vs. 0.70±0.09 ng/mL, P <0.05). Reverse transcription-quantitative PCR (RT-qPCR) showed that aldosterone synthase ( Cyp11b2 ) was decreased in AC of ieET-1 vs. ieCre mice (fold change: 0.52±0.06 vs. 1.00±0.16, P <0.01). CYP11B2 protein levels measured by Western Blotting was unchanged. Treatment with mineralocorticoid receptor antagonist eplerenone (100 mg/kg/day) during the last 2 weeks decreased daytime systolic BP determined by telemetry in ieET-1 vs. ieCre mice (Systolic after 14 days [mm Hg]: 128±1.6 vs. 137±1.8, P <0.01). The EC50 concentration for norepinephrine-induced MA contraction was reduced in ieET-1 vs. ieCre mice (EC50 [mol/L]: 5x10 -7 ±6x10 -8 vs. 4x10 -6 ±7x10 -7 , P <0.05), which was reversed by elplerenone (EC50 [mol/L]: 8x10 -6 ±5x10 -6 , P <0.05). The MA relaxation response to acetylcholine was decreased in ieET-1 vs. ieCre mice (32.2±5.3% vs. 70.5±5.9%), effect that was reduced by eplerenone (43.1±5.5%). The MA endothelium-independent relaxation response to sodium nitroprusside (SNP) was similar in ieET-1 and ieCre mice. Eplerenone enhanced sensitivity to SNP in iET-1 mice (EC50 [mol/L]: 3x10 -8 ±1x10 -8 vs. 1x10 -7 ±2x10 -8 , P <0.05).

Conclusions: Increased aldosterone production contributes to EC human ET-1 overexpression-induced daytime SBP elevation, enhanced contractile response to norepinephrine and endothelial dysfunction.

Abstract 126: Role of V γ6 + γδ T Cells in Angiotensin Il-Induced Hypertension and Vascular Injury

Introduction: Both innate and adaptive immune cells (such as T lymphocytes) have been shown to play a role in hypertension and vascular injury. Recently, we demonstrated that a small subpopulation of T cells considered "innate-like", expressing the γδ T-cell receptor (TCR) rather than the much more frequent αβ TCR, plays a key role in hypertension and vascular injury. The number and activation of γδ T cells were increased after 7 days of angiotensin (Ang) II infusion, and absence of γδ T cells prevented the development of hypertension, endothelial dysfunction of resistance arteries, and activation of CD4 + and CD8 + T cells in mice infused with Ang II for 14 days. γδ T cells can be subdivided according to the TCR variant (V) subtype that is generally specific for a tissue. A subpopulation of γδ T cells in the lungs and skin that are Vγ6 + and produce interleukin (IL)-17A was shown to respond promptly to pneumococcal infection and skin inflammation. However, γδ T cell Vγ subtypes involved in hypertension are still unknown. We hypothesized that γδ T cells involved in hypertension are Vγ6 + .

Methods: Eleven- to 13-week old C57BL/6J male mice were infused or not with Ang II (490 ng /kg /min, sc) for 14 days (n = 5-14), and γδ T cell Vγ subtypes were profiled by flow cytometry in the spleen, mesenteric lymph nodes (MLNs), thoracic aortic (TA), perivascular adipose tissue (PVAT) and mesenteric artery (MA) PVAT.

Results: In spleen and MLNs the most abundant γδ T cell Vγ subtypes were Vγ1,2 + and Vγ4 + followed by Vγ6 + , Vγ5 + and Vγ7 + . In TA PVAT, the most abundant γδ T cell Vγ subtype was Vγ6 + followed by Vγ4 + , Vγ1,2 + , Vγ5 + and Vγ7 + . In MA PVAT, the most abundant γδ T cell Vγ subtype was Vγ6 + followed by Vγ4 + , Vγ7 + , Vγ5 + and Vγ1,2 + . Ang II infusion increased the frequency of Vγ6 + γδ T cells in the spleen (% of CD3 + T cells: 0.77±0.09 vs. 0.5±0.02, P <0.01) and TA PVAT 5.9±0.8 vs. 3.6±0.4, P <0.01), whereas it only tended to increase in MA PVAT 14.5±1.7 vs. 10.2± 1.9, P =0.07). The Vγ6 + γδ T cell frequency in MLNs was unaffected by Ang II infusion.

Conclusion: A differential distribution of γδ T cell Vγ subtypes was observed in lymphoid organs compared to PVAT. Vγ6 + γδ T cells may play a role in hypertension. Targeting Vγ6 + γδ T cells could be a therapeutic approach to reduce inflammation in hypertension.

Abstract P150: Genes of a Brown Norway Chromosome 2 Fragment Introgressed Into Hypertensive Dahl Salt-Sensitive Background Exert Pro-Inflammatory Effects When Stimulated by a High-Salt Diet

Background: Chromosome 2 (Chr2) introgression from normotensive Brown Norway (BN) rats into hypertensive Dahl salt-sensitive (SS) background (consomic S B 2) reduced blood pressure (BP) and vascular inflammation under normal-salt diet (NSD). We hypothesized that BN Chr2 contains anti-inflammatory genes that could reduce BP elevation and vascular inflammation in rats fed NSD and high-salt diet (HSD).

Method: Four- to 6-week old male SS and congenic rats containing the BN Chr2 distal portion (S B 2a) and middle segment (S B 2b) were fed NSD or HSD (4% NaCl) for 8 weeks. We determined systolic BP (SBP) by telemetry, reactive oxygen species (ROS) generation using dihydroethidium staining, and vascular cell adhesion molecule 1 (VCAM-1), monocyte chemoattractant protein-1 (MCP-1) expression and monocyte/macrophage (MoMϕ) infiltration by immunofluorescence in aorta or perivascular fat (PVAT). RNA was extracted from aorta and used for small and total RNA sequencing and data were analyzed using a systems biology approach. Differentially expressed genes (DEGs) were identified with fold change >1.3 and fold discovery rate <0.05 and some of them were validated with RT-qPCR.

Results: SS SBP was 145±2 mm Hg under NSD and 168±1 mm Hg under HSD, which was lower in S B 2a and S B 2b SBP (125±3 and 127±6, P <0.05) under NSD but similar under HSD. Examination of ROS generation, VCAM-1 and MCP-1 expression and MoMϕ infiltration revealed that S B 2a present less and more inflammation under NSD and HSD, respectively, compared to SS. DEGs were identified in S B 2a vs SS uniquely under NSD (15↑ and 8↓) and HSD (318↑ and 221↓) and under both diet (3↑ and 3↓), and in S B 2b vs SS uniquely under NSD (43↑ and 65↓) and HSD (4↑ and 7 ↓) and under both diet (3↑ and 4 ↓). DEGs encoded within BN Chr2a were uniquely identified under NSD (1↑ and 1↓) and HSD (6↑ and 1↓), and in both diets (1↑ and 1↓). Gene enrichment analysis revealed that under NSD, 2 BN Chr2a DEGs are involved in regulation of BP, and under HSD, 7 BN Chr2a DEGs in cell proliferation, cell differentiation, signal transduction and the immune system. RT-qPCR validated DEGs encoded within BN Chr2a under NSD (2) and HSD (4).

Conclusions: DEGs encoded within BN Chr2a fragment are associated with anti- and pro-inflammatory effects under NSD and HSD, respectively.

Abstract P189: Human Endothelin-1 Overexpression in Mice Changed Gene Expression in Mesenteric Arteries

Background: Transgenic mice with tamoxifen-inducible endothelium-restricted human endothelin-1 overexpression (ieET-1) exhibited blood pressure (BP) elevation for 3 weeks or 3 months after induction. Vascular injury was observed only after 3-month exposure to human ET-1 overexpression. It is unknown whether 3-week or 3-month exposure to ET-1 overexpression results in gene dysregulation. We aimed to identify differentially expressed (DE) microRNAs (miRs) and genes in mesenteric arteries (MAs) of ieET-1 mice after 3-week and 3-month induction of human ET-1 overexpression.

Methods: Ten to 12-week-old male ieET-1 mice and control ieCre mice expressing a tamoxifen-inducible Cre recombinase under the control of endothelium-specific Tie2 promoter were treated with tamoxifen (1 mg/kg/day, s.c.) for 5 days and sacrificed 16 days or 3 months later. RNA was extracted from MAs of ieCre and ieET-1 mice for small and total RNA-sequencing using Illumina HiSeq-2500 and further studied using a systems biology approach. DE genes were identified with fold change >1.4 and P <0.005. DE genes were validated using another set of mice and type of vascular cells expressing them by reverse transcription-quantitative PCR (RT-qPCR).

Results: No DE miR were detected, while DE genes were identified after 3-week (15↑ and 39↓) and 3-month exposures to human ET-1 overexpression (4↑and 3↓). RT-qPCR validated 3 of 7 3-month DE genes: Khdrbs3 (KH domain containing, RNA binding, signal transduction associated 3), Aqp1 (Aquaporin 1) and Ly6e (Lymphocyte antigen 6 complex locus E). Khdrbs3 was increased and Ly6e decreased after 3-week and 3-month exposures to human ET-1 overexpression, while Aqp1 was increased only after 3-month exposure. In mice, Khdrbs3 and Ly6e were expressed in endothelial cells (ECs), smooth muscle cells (SMCs) and fibroblasts (FCs) and Aqp1 was more expressed in ECs and FCs. In humans, KHDRBS3 was expressed in the 3 vascular cell types, LY6E more in FCs, and AQP1 more in ECs.

Conclusions: Exposure for 3 weeks and 3 months to endothelial human ET-1 overexpression changed the expression of Khdrbs3, Ly6e and Aqp1 in MAs. Vascular cells expressing these genes were identified. However, their role in ET-1-induced vascular injury remains to be determined.

Abstract 023: γδ T Cells Mediate αβ T Cell Activation in Angiotensin II-Induced Hypertension

Objectives: Both innate and adaptive immune cells have been shown to play a role in hypertension and vascular injury. Recently, we demonstrated that a small subset of “innate-like” T lymphocytes, expressing the γδ T cell receptor (TCR) rather than the αβ TCR, plays a key role in hypertension and vascular injury. We demonstrated an increased number and activation (CD69 + ) of αβ and γδ T cells during the development of hypertension caused by angiotensin (Ang) II infusion, and that deficiency in γδ T cells prevented Ang II-induced hypertension, resistance artery endothelial dysfunction and spleen T-cell activation in mice. We hypothesized that γδ T cells mediate activation of other T cells in hypertension.

Methods: C57BL/6 male mice were infused with Ang II (490 ng/kg/min, SC) for 7 and 14 days (n=5-7). All mice were 14-15 week-old at the end of the study. Spleen T cell profile was determined by flow cytometry. γδ and αβ T cells were isolated using magnetic beads from peripheral lymph nodes and spleen from C57BL/6 male mice treated or not with Ang II for 14 days. αβ T cells were cultured alone or with γδ T cells (5:1) in presence of anti-CD3 antibodies plus or minus Ang II, and αβ T cell phenotype was evaluated by flow cytometry.

Results: Close correlations were demonstrated between the number (#) of activated CD69 + γδ T cells and CD4 + CD69 + T cells (r 2 =0.74, P <0.01) and CD8 + CD69 + T cells (r 2 =0.64, P <0.01) after 7-day Ang II infusion. Correlations were also shown between the # of CD27 + CD69 + γδ T cells and CD4 + CD69 + T cells (r 2 =0.76, P <0.001) and CD8 + CD69 + T cells (r 2 =0.65, P <0.01) after 7-day Ang II infusion. In vitro , Ang II increased the fraction of CD69 + αβ T cells when αβ T cells were co-cultured with γδ T cells isolated from control mice (% of αβ T cells: 19.9±2.9 vs. 16.4±2.6, P <0.001) but not when cultured alone. The fractions of CD69 + (% of CD69 + αβ T cells: 35.7±2.7 vs. 18.9±1.5, P <0.001) and CCR6 + αβ T cells (% of CCR6 + αβ T cells: 27.6±2.4 vs. 19.2±3.5, P <0.05) were increased when αβ T cells were co-cultured with γδ T cells isolated from Ang II-infused compared to control mice.

Conclusions: These results suggest that γδ T cells mediate activation of αβ T cells in Ang II-induced hypertension. Targeting γδ T cells may contribute to reduce the low-grade inflammation found in hypertension.

Overproduction of endothelin-1 impairs glucose tolerance but does not promote visceral adipose tissue inflammation or limit metabolic adaptations to exercise

Endothelin-1 (ET-1) is a potent vasoconstrictor and proinflammatory peptide that is upregulated in obesity. Herein, we tested the hypothesis that ET-1 signaling promotes visceral adipose tissue (AT) inflammation and disrupts glucose homeostasis. We also tested if reduced ET-1 is a required mechanism by which exercise ameliorates AT inflammation and improves glycemic control in obesity. We found that 1) diet-induced obesity, AT inflammation, and glycemic dysregulation were not accompanied by significantly increased levels of ET-1 in AT or circulation in wild-type mice and that endothelial overexpression of ET-1 and consequently increased ET-1 levels did not cause AT inflammation yet impaired glucose tolerance; 2) reduced AT inflammation and improved glucose tolerance with voluntary wheel running was not associated with decreased levels of ET-1 in AT or circulation in obese mice nor did endothelial overexpression of ET-1 impede such exercise-induced metabolic adaptations; 3) chronic pharmacological blockade of ET-1 receptors did not suppress AT inflammation in obese mice but improved glucose tolerance; and 4) in a cohort of human subjects with a wide range of body mass indexes, ET-1 levels in AT, or circulation were not correlated with markers of inflammation in AT. In aggregate, we conclude that ET-1 signaling is not implicated in the development of visceral AT inflammation but promotes glucose intolerance, thus representing an important therapeutic target for glycemic dysregulation in conditions characterized by hyperendothelinemia. Furthermore, we show that the salutary effects of exercise on AT and systemic metabolic function are not contingent on the suppression of ET-1 signaling.

Abstract P1113: P2x7 Receptor Plays a Role in Angiotensin II-Induced Hypertension and Vascular Remodeling

Introduction: Inflammasome activation by binding of ATP released from damaged cells to the purinergic receptor P2X7 (P2RX7) could play a role in hypertension and vascular injury through release of interleukin (IL)-1β and immune cell activation. Elevated ATP levels were observed in the renal interstitial fluid of angiotensin (Ang) II-infused rats, and treatment of these rats with a non-selective P2 receptor blocker prevented Ang II-induced inflammation and renal damage. P2RX7 knockout ( P2rx7 –/– ) prevented deoxycorticosterone acetate-salt-induced blood pressure (BP) elevation and renal damage. However, it is unknown whether P2RX7 plays a role in Ang II-induced BP elevation and vascular damage. We hypothesize that Ang II-induced hypertension, vascular injury, and inflammation will be blunted in P2rx7 -/- mice.

Methods: Ten to 12-week-old male C57BL/6J male wild-type (WT) and P2rx7 –/– mice were sham-treated or infused with Ang II (490ng/kg/min) for 14 days. BP was determined by telemetry. Mesenteric artery function and remodeling was assessed using pressurized myography. P2RX7 expression in spleen immune cells was determined by flow cytometry. IL-1β secretion from bone marrow-derived macrophages (BMDM) isolated from WT and P2rx7 –/– mice was assessed by ELISA.

Results: Stimulation with lipopolysaccharides and ATP caused IL-1β release in WT (339±162 pg/mL) but not P2rx7 –/– BMDMs. In WT mice, Ang II increased P2RX7 expression in dendritic cells (mean fluorescence intensity: 1927±120 vs 3983±983) and macrophages (2541±265 vs 3314±273 respectively). P2rx7 knockout reduced Ang II-induced systolic (159±3 vs 165±7 mm Hg) and diastolic BP elevation (110±4 vs 126 ±7 mm Hg) compared to WT mice. Acetylcholine-induced vascular relaxation was unaffected by Ang II or P2rx7 knockout. Ang II increased the media-to-lumen ratio in WT (4.71±0.18% vs 3.89±0.21%, P <0.01) but not in P2rx7 –/– mice.

Conclusion: This study demonstrated that P2RX7 plays a role in Ang II-induced hypertension and vascular remodeling.

Abstract P223: Identification of Chromosome 2 Differentially Expressed Genes Linked to Vascular Inflammation Using Congenic Rats Fed a Normal and High-Salt Diet

Background: The immune system plays an important role in hypertension. Chromosome 2 (Chr2) introgression from normotensive Brown Norway (BN) rats into hypertensive Dahl salt sensitive (SS) background (consomic SB2) reduced blood pressure (BP), and vascular inflammation under a normal-salt diet (NSD). We hypothesized that BN Chr2 contains anti-inflammatory genes that could prevent BP elevation and vascular inflammation in rats fed NSD and high-salt diet (HSD). These genes will be identified using microRNA (miRNA) and total RNA sequencing in aorta of congenic rats containing different portions of BN Chr2 under NSD and HSD.

Methods and Results: Four-to-6 week-old male SS and congenic SB2a and SB2b rats were fed a NSD or HSD (4% NaCl) for 8 weeks. Telemetry systolic BP (SBP) was lower in SB2a and SB2b compared to SS (125±3, 127±6 vs 146±2 mm Hg, P <0.05) under NSD and tended to be higher in SB2b but not in SB2a when compared to SS (185±8, 167±7 vs 168±5 mm Hg) under HSD. RNA was extracted from aorta and used for small and total RNA sequencing using Illumina HiSeq-2500. Differentially expressed (DE) miRNAs and genes (mRNAs and non-coding RNAs [ncRNAs]) encoded in BN Chr2 introgressed portions were identified with fold change ≤ or ≥1.5 and FDR<0.05 in SB2a vs SS (miRNAs: 2 up (↑) and 2 down (↓), mRNAs: 8 ↑ and 10 ↓, ncRNA: 1 ↓) under NSD and (miRNAs: 12 ↑ and 14 ↓; mRNAs: 188↑ and 259 ↓, ncRNAs: 1 ↑ and 11 ↓) under HSD; and SB2b vs SS (miRNAs: 2 ↑ and 4 ↓, mRNAs: 26 ↑ and 85 ↓; ncRNAs: 1 ↑ and 2 ↓) under NSD and (mRNAs: 6 ↑ and 11 ↓, ncRNAs: 1 ↑ and 3 ↓) under HSD. Ddah1 was down-regulated in SB2a vs SS rats fed NSD and HSD, while Acad9 , Agtr1b, ncRNA AABR07012047.1 , Fbxw7, Ptgfrn were down-regulated and ncRNA AABR07012585.3 , Bbs12, Kcnab1 were up-regulated in SB2b vs SS rats fed NSD and HSD. DE RNAs were confirmed by reverse transcription-quantitative PCR (RT-qPCR). Correlation between RNA-sequencing and RT-qPCR data was demonstrated for 6 of 9 tested RNAs: Kcnab1 (r=0.86, P <3.3E-9), Agtr1b (r=0.85, P <6E-9), Ddah1 (r=0.78 , P <5.0E-7) , Bbs12 (r=0.72, P <6.4E-6), Ptgfrn (r=0.54, P <0.005), and AABR07012047.1 (r=0.48, P <0.05).

Conclusions: BN Chr2 encoded DE genes were identified in aorta of congenic SB2a and SB2b rats fed NSD and HSD. Whether these genes play a role in vascular inflammation remains to be determined.

Abstract P151: Short- and Long-Term Induction of Human Endothelin-1 Overexpression in Mice Up-Regulated the Expression of Khdrbs3 in Mesenteric Arteries

Background: Transgenic mouse with tamoxifen-inducible endothelium-restricted human ET-1 overexpression (ieET-1) exhibited blood pressure (BP) elevation three weeks (short-term) and three months after induction (long-term). Vascular injury was observed only after long-term exposure to endothelial ET-1 overexpression. It is unknown whether short or long-term exposure to ET-1 overexpression results in gene dysregulation. We aimed to identify differentially expressed (DE) microRNAs (miRs) and genes in mesenteric arteries of ieET-1 mice after short- and long-term induction of human ET-1 overexpression.

Methods and Results: Ten to 12-week old male ieET-1 mice and control ieCre mice expressing a tamoxifen-inducible Cre recombinase under the control of endothelium-specific Tie2 promoter, were treated with tamoxifen (1 mg/kg/day, s.c.) for 5 days and sacrificed 16 days or 3 month later. RNA was extracted from mesenteric arteries of ieCre and ieET-1 mice and used for small and total RNA-sequencing using Illumina HiSeq-2500. EdgeR was used for differential expression analysis (false discovery rate <0.05, fold change ≤ or ≥ 1.5). No DE miRs were identified. DE genes were identified in ieET-1 compared to ieCre mice after short-term induction (mRNAs: 1 up and 6 down; non-coding [nc]RNAs: 3 up) and after long-term induction (mRNA: 1 up). Khdrbs3 (KH domain containing, RNA binding, signal transduction associated 3), which was up-regulated after both short- and long-term exposure to endothelial ET-1 overexpression, was validated by reverse transcription-quantitative PCR (RT-qPCR). We demonstrated a correlation between RNA-sequencing and RT-qPCR data for short- and long-term groups (r=0.8, P <0.0005). The mRNA expression of Khdrbs3 was 2 times more in fibroblasts than in smooth muscle cells and endothelial cells (2.37±0.28 vs. 1.11±0.17 and 1.12±0.12, P <0.01).

Conclusions: The results showed that short- and long-term exposure to endothelial ET-1 overexpression up-regulated Khdrbs3 in mesenteric arteries. In vitro study revealed that this gene was expressed to a greater level in fibroblasts than other vascular cells. However, the role of Khdrbs3 in ET-1-induced vascular injury remains to be determined.

Abstract P116: Induction of Human Endothelin-1 Overexpression for 3 Months Increases Plasma Aldosterone

Background: The mechanisms of blood pressure (BP) regulation by endothelin (ET)-1 produced by endothelial cells are complex and remain unclear. Long-term exposure to endothelial human ET-1 overexpression causes sustained blood pressure elevation via ETA receptors. ET-1 has been shown to stimulate the release of aldosterone from the adrenal cortex. Whether aldosterone plays a role in ET-1 endothelium overexpression-induced BP elevation is still unknown.

Methods and Results: Nine to 12-week-old male ieET-1 mice and control ieCre mice expressing a tamoxifen-inducible Cre recombinase (CreER T2 ) under the control of EC-specific Tie2 promoter, were treated with tamoxifen (1 mg/kg/day, SC) for 5 days and studied 3 months later. Plasma aldosterone level measured by ELISA was higher in ieET-1 compared with ieCre mice (1.21±0.14 vs. 0.70±0.09 ng/mL, P <0.05). Sodium and water excretion determined by saline challenge tests done every 2 weeks for 3 months were unaffected by ET-1 overexpression. Reverse transcription-quantitative PCR (RT-qPCR) did not reveal changes in mRNA expression of renin, mineralocorticoid receptor (MR), epithelial sodium channel 1 alpha subunit ( Scnn1a ), TSC22 domain family member 3 ( Rsc22d3 ), serum- and glucocorticoid-induced kinase 1 ( Sgk1 ), and ET type A and B receptors in the kidney or adrenal glands. The mRNA expression of aldosterone synthase ( Cyp11b2 , fold change: 0.52±0.06 vs 1.00±0.16, P <0.01), but not the hydroxy-delta-5-steroid dehydrogenase 3 beta- and steroid delta-isomerase 1 ( Hsd3b1) and 6 (Hsd3b6) or steroidogenic acute regulatory protein ( Star ), were decreased in the adrenal cortex of ieET-1 compared with ieCre mice. CYP11B2 and HSD3B1 protein levels measured by Western Blotting were unchanged. Treatment of ieET-1 mice with MR antagonist eplerenone (100 mg/kg per day) during the last 2 weeks decreased systolic BP more during the day (128±2 vs. 134±3 mm Hg) than during the night (137±2 vs. 140±2 mm Hg) compared to untreated ieET-1 mice.

Conclusions: These results showed that aldosterone contributes at least in part to the BP elevation caused by endothelial human ET-1 overexpression.

Abstract P283: Gamma Delta T Cells Drive CD4 + and CD8 + T Cell Activation in Hypertension

Objective: Both innate (monocyte/macrophages) and adaptive immune cells (T lymphocytes) have been shown to play a role in hypertension and vascular injury. Recently, we demonstrated that a small subset of “innate-like” T lymphocytes, expressing the γδ T cell receptor (TCR) rather than the αβ TCR, plays a key role in hypertension and vascular injury. We demonstrated an increased number and activation (CD69 + ) of γδ T cells during the development of hypertension caused by angiotensin (Ang) II infusion, and that deficiency in γδ T cells prevented Ang II-induced hypertension, resistance artery endothelial dysfunction and spleen T-cell activation in mice. We hypothesized that γδ T cells mediate activation of other T cells in hypertension.

Method: C57BL/6 male mice were infused with Ang II (490 ng/kg/min, SC) for 7 and 14 days (n=5-7). All mice were 14-15 week-old at the end of the study. Spleen T cell profile was determined by flow cytometry. γδ and αβ T cells were isolated using magnetic beads from peripheral lymph nodes and spleen of 8 to 9-week-old C57BL/6 male mice. αβ T cells were cultured alone or with γδ T cells (5:1) in presence of anti-CD3 antibodies plus or minus Ang II, and αβ T cell activation was evaluated by flow cytometry.

Results: Close correlations were demonstrated between the number (#) of activated CD69 + γδ T cells and CD4 + CD69 + T cells (r 2 =0.74, P <0.01) and CD8 + CD69 + T cells (r 2 =0.64, P <0.01) after 7-day Ang II. These correlations decreased after 14-day Ang II. Correlations were also shown between the # of CD27 + CD69 + γδ T cells and CD4 + CD69 + T cells (r 2 =0.76, P <0.001) and CD8 + CD69 + T cells (r 2 =0.65, P <0.01) after 7-day Ang II. In vitro , Ang II increased the fraction of CD69 + αβ T cells when αβ T cells were co-cultured with γδ T cells (% of αβ T cells: 19.9±2.9 vs. 16.4±2.6, P <0.001) but not when cultured alone (% of αβ T cells: 13.7±0.7 vs. 12.7±0.6). A correlation between the fraction of CD69 + γδ T cells and CD69 + αβ T cells was also observed (r 2 =0.69, P <0.001).

Conclusion: These results suggest that γδ T cells mediate activation of αβ T cells in Ang II-induced hypertension. Targeting γδ T cells may contribute to reduce the low-grade inflammation found in hypertension.

Matrix metalloproteinase-2 knockout prevents angiotensin II-induced vascular injury

Aims

Matrix metalloproteinases (MMPs) have been implicated in the development of hypertension in animal models and humans. Mmp2 deletion did not change Ang II-induced blood pressure (BP) rise. However, whether Mmp2 knockout affects angiotensin (Ang) II-induced vascular injury has not been tested. We sought to determine whether Mmp2 knockout will prevent Ang II-induced vascular injury.

Methods and results

A fourteen-day Ang II infusion (1000 ng/kg/min, SC) increased systolic BP, decreased vasodilatory responses to acetylcholine, induced mesenteric artery (MA) hypertrophic remodelling, and enhanced MA stiffness in wild-type (WT) mice. Ang II enhanced aortic media and perivascular reactive oxygen species generation, aortic vascular cell adhesion molecule-1 and monocyte chemotactic protein-1 expression, perivascular monocyte/macrophage and T cell infiltration, and the fraction of spleen activated CD4+CD69+ and CD8+CD69+ T cells, and Ly-6Chi monocytes. Study of intracellular signalling showed that Ang II increased phosphorylation of epidermal growth factor receptor and extracellular-signal-regulated kinase 1/2 in vascular smooth muscle cells isolated from WT mice. All these effects were reduced or prevented by Mmp2 knockout, except for systolic BP elevation. Ang II increased Mmp2 expression in immune cells infiltrating the aorta and perivascular fat. Bone marrow (BM) transplantation experiments revealed that in absence of MMP2 in immune cells, Ang II-induced BP elevation was decreased, and that when MMP2 was deficient in either immune or vascular cells, Ang II-induced endothelial dysfunction was blunted.

Conclusions

Mmp2 knockout impaired Ang II-induced vascular injury but not BP elevation. BM transplantation revealed a role for immune cells in Ang II-induced BP elevation, and for both vascular and immune cell MMP2 in Ang II-induced endothelial dysfunction.

Role of immune cells in hypertension

Inflammatory processes have been shown to play an important role in the mechanisms involved in the pathogenesis of hypertension. Innate and adaptive immune responses participate in BP elevation and end-organ damage. Here, we discuss recent studies focusing on novel inflammatory and immune mechanisms that play roles in BP elevation. Different subpopulations of cells involved in innate and adaptive immune responses, such as dendritic cells, monocytes/macrophages and NK cells, on the one hand, and B and T lymphocytes, on the other, contribute to the vascular and kidney injury in hypertension. Unconventional innate-like T cells such as γδ T cells also participate in hypertensive mechanisms by priming both innate and adaptive immune cells, contributing to trigger vascular inflammation and BP elevation. These cells exert their effects in part via production of various cytokines including pro-inflammatory IFN-γ and IL-17 and anti-inflammatory IL-10. The present review summarizes some of these immune mechanisms that participate in the pathophysiology of hypertension. LINKED ARTICLES: This article is part of a themed section on Immune Targets in Hypertension. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v176.12/issuetoc.

Angiotensin II Overstimulation Leads to an Increased Susceptibility to Dilated Cardiomyopathy and Higher Mortality in Female Mice

Heart failure (HF) is associated with high mortality and affects men and women differently. The underlying mechanisms for these sex-related differences remain largely unexplored. Accordingly, using mice with cardiac-specific overexpression of the angiotensin II (ANGII) type 1 receptor (AT1R), we explored male-female differences in the manifestations of hypertrophy and HF. AT1R mice of both sexes feature electrical and Ca²⁺ handling alterations, systolic dysfunction, hypertrophy and develop HF. However, females had much higher mortality (21.0%) rate than males (5.5%). In females, AT1R stimulation leads to more pronounced eccentric hypertrophy (larger increase in LV mass/body weight ratio [+31%], in cell length [+27%], in LV internal end-diastolic [LVIDd, +34%] and systolic [LVIDs, +67%] diameter) and dilation (larger decrease in LV posterior wall thickness, +17%) than males. In addition, in female AT1R mice the cytosolic Ca²⁺ extrusion mechanisms were more severely compromised and were associated with a specific increased in Ca²⁺ sparks (by 187%) and evidence of SR Ca²⁺ leak. Altogether, these results suggest that female AT1R mice have more severe eccentric hypertrophy, dysfunction and compromised Ca²⁺ dynamics. These findings indicate that females are more susceptible to the adverse effects of AT1R stimulation than males favouring the development of HF and increased mortality.

Abstract P347: γδ T Cells Drive CD4 + And CD8 + T Cell Activation In Hypertension

Objective: Both innate (monocyte/macrophages) and adaptive immune cells (T lymphocytes) have been shown to play a role in the development of vascular injury in hypertension. Recently, we demonstrated that a small subset of “innate-like” T lymphocytes, expressing the γ/δ T cell receptor (TCR) rather than the αβ TCR, plays a key role in hypertension and vascular injury. We demonstrated an increased number and activation (CD69 + ) of γδ T cells during the development of hypertension caused by angiotensin (Ang) II infusion, and that deficiency in γδ T cells prevented Ang II-induced hypertension, resistance artery endothelial dysfunction and spleen T-cell activation in mice. We hypothesized that γδ T cells mediate activation of other T cells in hypertension.

Method and Results: Fourteen to 15-week old male C57BL/6 wild-type (WT) mice were infused with Ang II (490 ng/kg/min, SC) for 3, 7 and 14 days (n=5-7) and spleen T cell profile was determined by flow cytometry. A correlation was demonstrated between the frequency (FREQ) and the number (#) of activated CD69 + γδ T cells and CD4 + CD69 + T cells (FREQ: r=0.41, P <0.05 and #: r=0.58, P <0.001) and CD8 + CD69 + T cells (FREQ: r=0.36, P <0.05 and #: r=0.50, P <0.01). We also demonstrated a high correlation between the # of CD69 + γδ T cells expressing CD27, a marker of interferon-γ expressing cells and a member of the T-T interaction molecules, with CD4 + CD69 + (r=0.88, P <0.001) and CD8 + CD69 + (r=0.81, P <0.01) T cells after 7 days of Ang II infusion.

Conclusion: This study demonstrated an association between CD27 + CD69 + γδ T cells and activated T cells. These results suggest that γδ T cells drive activation of other T cells in Ang II-induced hypertension. Targeting γδ T cells may contribute to reduce inflammation in hypertension.

Abstract P159: MicroRNA Profiling in Small Resistance Arteries of Hypertensive Patients With or Without Chronic Kidney Disease

Background: Hypertension (HTN) and chronic kidney disease (CKD) are global health disorders that are epidemiologically associated. Vascular injury is an early manifestation in HTN and contributes to CKD. It is characterized by endothelial dysfunction and vascular remodeling that are accompanied by gene expression changes. MicroRNAs (miRs) are important non-coding RNA regulators of gene expression. Dysregulation of miRs has been shown in HTN and CKD, but their implication in vascular injury remains unclear. We aimed to identify differentially expressed (DE) miRs in small arteries of HTN and CKD human subjects to get further insight into pathophysiological molecular mechanisms in these conditions.

Methods and Results: Normotensive, HTN (systolic blood pressure (BP) > 135 mm Hg or diastolic BP of 85-115 mm Hg with BpTRU) and CKD subjects (estimated glomerular filtration rate <60mL/min/m 2 ) (n=15-16) were studied. Small arteries were dissected from a subcutaneous gluteal biopsy under RNAse free condition and used for total RNA extraction with the mirVana miR isolation kit. cDNA libraries were prepared using the TruSeq small RNA prep kit and the TruSeq stranded total RNA prep kit, and sequenced by Illumina HiSeq 2500. DE miRs and DE mRNAs ( P <0.05) were identified using EdgeR, which found 3 up- and 6 down-regulated miRs, as well as 134 up- and 149 down-regulated mRNAs uniquely associated with HTN, 42 up- and 39 down-regulated miRs, as well as 743 up- and 348 down-regulated mRNAs uniquely associated with CKD, while 2 up-regulated miRs and 101 up- and 75 down-regulated mRNAs were found in both groups. Target Scan was used to predict DE miR targets in the DE mRNAs. Enrichment analysis showed that the HTN-associated DE miR-targeting DE mRNAs were highly enriched in gene ontology (GO) terms involved in peptidase activity, mitochondrial activity and immune response ( q <0.01), while the CKD-associated DE miR-targeting DE genes were highly enriched in GO terms involved in tube formation, fibroblast proliferation and EGF response ( q <0.001).

Conclusions: DE miRs were identified in small arteries of HTN and CKD patients. Enrichment analysis in DE miR-targeting DE mRNAs revealed GO terms that could be linked to different degrees of vascular changes in HTN and CKD.