Vascular Smooth Muscle Research Articles

Nuclear receptor subfamily 4 group a member 1 eases angiotensin II-arose oxidative stress in vascular smooth muscle cell by boosting nucleotide-binding oligomerization domain-like receptor family caspase recruitment domain containing 3 transcription

Objective: Hypertension significantly contributes to morbidity and mortality. Nuclear receptor subfamily 4 group a member 1 (Nur77) participates in regulating oxidative stress, but the mechanism in hypertension remains unclear. This study aimed to explore the function of Nur77 in oxidative stress induced by Angiotensin II (Ang II) in vascular smooth muscle cells (VSMCs) in hypertension. Material and Methods: First, models of VSMC with Nur77, nucleotide-binding oligomerization domain-like receptor family caspase recruitment domain containing 3 (NLRC3) and tumor necrosis factor receptor-associated factor 6 (TRAF6) knockdown or overexpression were constructed using Short Hairpin RNA (Nur77) or pcDNA3.1 vector, respectively. Next, the putative-binding motifs between Nur77 and NLRC3 promoters were detected by dual luciferase assay. We conducted reverse transcription quantitative polymerase chain reaction (qPCR) and Western blot (WB) analysis to detect Nur77, NLRC3, and TRAF6 levels in VSMCs. Then, cell counting kit-8 assay, 5-ethynyl-2’-deoxyuridine assay, wound-healing assay, enzyme-linked immunosorbent assay, and 2’,7’-dichlorofluorescin diacetate were employed to examine the impact of the knockdown or overexpression of Nur77, NLRC3, and TRAF6 on VSMCs treated with Ang II. The assays measured cell viability and proliferation, cell migration, malondialdehyde levels, and reactive oxygen species levels. Results: The overexpression of Nur77 repressed cell growth (P < 0.001), migration (P < 0.01), and oxidative stress (P < 0.01) induced by Ang II in VSMCs. Nur77 transcriptionally promoted the expression of NLRC3 (P < 0.001), and the upregulation of NLRC3 suppressed cell proliferation (P < 0.05) and oxidative stress (P < 0.001) mediated by Ang II. Furthermore, NLRC3 negatively regulated the TRAF6/nuclear factor-kappa B (NF-κB) axis activated by Ang II, which resulted in the repression of hyperproliferation of VSMCs (P < 0.01) and oxidative stress (P < 0.001). Conclusion: Nur77 suppressed growth and oxidative stress induced by Ang II in VSMCs by promoting NLRC3 transcription, which, further, repressed the TRAF6/NF-κB axis. This understanding provides novel insights into the pathogenesis of hypertension.

HIF-1α knockdown attenuates phenotypic transformation and oxidative stress induced by high salt in human aortic vascular smooth muscle cells.

Increased dietary salt intake is a well-established risk factor for hypertension and related cardiovascular diseases, involving complex vascular remodeling processes. However, the specific role of hypoxia-inducible factor-1α (HIF-1α) in vascular pathophysiology under high-salt conditions remains poorly understood. This study investigates the role of HIF-1α in high-salt-induced vascular remodeling using human aortic vascular smooth muscle cells (HA-VSMCs) cultured in vitro. HA-VSMCs were divided into three groups: high-salt with HIF-1α knockdown (shHIF-1α + HS), negative control (shcontrol), and high-salt (HS). Cell viability, migration, gene expression, and protein levels were evaluated. High-salt conditions significantly increased mRNA expression of α-smooth muscle actin (α-SMA), smooth muscle protein 22 (SM22), angiotensin II type 1 receptor (AT1R), collagen I, and collagen III (p < 0.0001). HIF-1α knockdown partially attenuated these increases, particularly for α-SMA, SM22, and AT1R (p < 0.01). At the protein level, high-salt exposure markedly elevated expression of collagen III, HIF-1α, osteopontin (OPN), and angiotensin II (Ang II) (p < 0.0001). HIF-1α knockdown significantly reduced the high-salt-induced increases in collagen III and HIF-1α protein levels (p < 0.001) but had a limited effect on OPN and Ang II upregulation. Interestingly, SM22 protein expression was significantly decreased under high-salt conditions (p < 0.0001), an effect partially reversed by HIF-1α knockdown (p < 0.0001). These findings demonstrate that high-salt conditions induce complex changes in gene and protein expression in HA-VSMCs, with HIF-1α playing a crucial role in mediating many of these alterations. The study highlights the differential effects of HIF-1α on various markers of vascular remodeling and suggests that HIF-1α may be a potential therapeutic target for mitigating salt-induced vascular pathology. Further research is warranted to elucidate the mechanisms underlying the HIF-1α-dependent and -independent effects observed in this study.

Echinochrome A inhibits HMGB1-induced vascular smooth muscle cell migration by suppressing osteopontin expression.

Echinochrome A (Ech A) isolated from marine organisms is a therapeutic effector for various cardiovascular diseases, but its precise mechanisms are unclear. This study identified the role and mechanisms mediating the effects of Ech A on the migration of vascular smooth muscle cells (VSMCs) induced by high-mobility group box 1 (HMGB1). Compared to the control cells, the migration of VSMCs stimulated with HMGB1 (100 ng/ml) was markedly increased, which was significantly attenuated in cells pretreated with MPIIIB10 (100 ng/ml), a neutralizing monoclonal antibody for osteopontin (OPN). In VSMCs stimulated with HMGB1, the increased expression of OPN mRNA and protein was accompanied by an increased OPN promoter activity. In reporter gene assays using OPN promoter-luciferase constructs, the promoter region 538-234 bp of the transcription start site containing the binding sites for activator protein 1 (AP-1) was shown to be responsible for the increased transcriptional activity by HMGB1. In addition, the binding activity of AP-1 was increased in HMGB1-stimulated cells, highlighting the pivotal role of AP-1 on OPN expression in HMGB1-stimulated VSMCs. An examination of the vascular effects of Ech A showed that the increased AP-1 binding/promoter activities and OPN expression induced by HMGB1 were attenuated in cells pretreated with Ech A (3 or 10 μM). Similarly, Ech A inhibited HMGB1-induced VSMC migration in a concentration-dependent manner. These findings suggest that Ech A inhibits VSMC migration by suppressing OPN expression. Hence, Ech A is suggested as a potential therapeutic strategy for vascular remodeling in the injured vasculatures.

Rosuvastatin activates autophagy via inhibition of the Akt/mTOR axis in vascular smooth muscle cells.

The proliferation and migration of vascular smooth muscle cells (VSMCs) are key contributors to the development of atherosclerosis and restenosis. We investigated the impact of rosuvastatin (RSV) on platelet-derived growth factor (PDGF)-BB-induced proliferation and migration of VSMCs, with a focus on the Akt/mTOR-autophagy signaling pathways. The cytotoxicity of RSV was assessed using MTT and annexin V staining, while the proliferation and migration capabilities of PDGF-BB-induced VSMCs were evaluated using MTT and cell migration assays. Confocal microscopy was employed to examine autophagic cell images, and protein expressions were analyzed via Western blotting. Our key findings revealed that RSV inhibited PDGF-BB-induced proliferation and migration of VSMCs, significantly reducing the expression of proliferating cell nuclear antigen and matrix metalloproteinase-2, which are crucial for these processes. RSV also enhanced autophagy in PDGF-BB-stimulated cells by inducing the maturation of microtubule-associated protein light chain 3 and increasing the expression of Beclin-1, autophagy related (Atg)3, Atg5, and Atg7. The regulatory effects of RSV on PDGF-BB-induced autophagy, proliferation, and migration were associated with the suppression of the Akt/mTOR signaling pathway. These findings suggest that RSV may have potential therapeutic benefits in preventing and treating vascular diseases by targeting the Akt/mTOR pathway and inducing autophagy.

Serum uric acid is independently associated with impaired nitroglycerine-induced vasodilation of the brachial artery in women.

Experimental and clinical studies have suggested atherosclerotic effects of uric acid (UA) on vascular smooth muscle cells (VSMCs). Nitroglycerine-induced vasodilation (NID), a control test for flow-mediated vasodilation, can be used as a possible marker of VSMC dysfunction. However, there is little information on the association between UA and NID. Therefore, we investigated the association between serum UA levels and NID according to sex. We measured NID of the brachial artery in 598 women (mean age: 66.2 ± 12.0 years) and 1008 men (mean age: 59.0 ± 18.0 years). In women, the mean serum UA level was 5.06 ± 1.24 mg/dL. Serum UA levels were negatively correlated with NID (p < 0.001), and NID significantly decreased with increasing serum UA levels (≤4.0 mg/dL, 13.4 ±6.4%; 4.0 to ≤5.0 mg/dL, 11.4 ± 5.3%; 5.0 to ≤6.0 mg/dL, 10.8 ± 5.7%; >6.0 mg/dL, 9.7 ± 5.7%; p < 0.001). The prevalence of VSMC dysfunction, defined as NID < 8.4%, the division points for the lowest and middle tertiles of NID in women, increased with increasing serum UA levels ( ≤ 4.0 mg/dL, 23.3%; 4.0 to ≤5.0 mg/dL, 30.9%; 5.0 to ≤6.0 mg/dL, 36.4%; >6.0 mg/dL, 44.6%; p < 0.001). Multiple logistic regression analysis showed a significant association between serum UA levels and VSMC dysfunction (odds ratio, 1.21; 95% confidence interval, 1.02─1.43; p = 0.03). There was no interaction between age (<50 or ≥50 years) and the effect of serum UA levels on VSMC dysfunction (p interaction = 0.88). In contrast, no association was observed between serum UA levels and NID in men. Serum UA levels were significantly associated with VSMC dysfunction as assessed by NID in women.

The alarmin, interleukin-33, increases vascular tone via extracellular signal regulated kinase-mediated Ca2+ sensitization and endothelial nitric oxide synthase inhibition.

Alarmins are classified by their release from damaged or ruptured cells. Many alarmins have been found to increase vascular tone and oppose endothelium-dependent dilatation (EDD). Interleukin (IL)-33 plays a prominent role in lung injury and can be released during vascular injury and in chronic studies found to be cardioprotective. Our recent work has implicated IL-33 in acute vascular dysfunction following inhalation of engineered nanomaterials (ENM). However, the mechanisms linking IL-33 to vascular tone have not been interrogated. We therefore aimed to determine whether IL-33 directly influenced microvascular tone and endothelial function. Isolated feed arteries and in vivo arterioles from male and female Sprague-Dawley rats were used to determine direct vascular actions of IL-33. Mesenteric feed arteries and arterioles demonstrated reduced intraluminal diameters when treated with increasing concentrations of recombinant IL-33. IL-33 activated extracellular signal regulated kinase (ERK)1/2 of rat aortic smooth muscle cells but not phosphorylation of myosin light chain kinase. This suggested IL-33may sensitize arterioles to Ca2+-mediated responses. Indeed, IL-33 augmented the myogenic- and phenylephrine-induced vasoconstriction. Additionally, incubation of arterioles with 1ng IL-33 attenuated ACh-mediated EDD. Mechanistically, in human aortic endothelial cells, we demonstrate that IL-33-mediated ERK1/2 activation leads to inhibitory phosphorylation of serine 602 on endothelial nitric oxide synthase. Finally, we demonstrate that IL-33-ERK1/2 contributes to vascular tone following two known inducers of IL-33; ENM inhalation and the rupture endothelial cells. The present study provides novel evidence that IL-33 increases vascular tone via canonical ERK1/2 activation in microvascular smooth muscle and endothelium. Altogether, it is suggested IL-33 plays a critical role in microvascular homeostasis following barrier cell injury. KEY POINTS: Interleukin (IL)-33 causes a concentration-dependent reduction in feed artery diameter. IL-33 acts on vascular smooth muscle cells to augment Ca2+-mediated processes. IL-33 causes inhibitory phosphorylation of endothelial nitric oxide synthase and opposes endothelium-dependent dilatation. Engineered nanomaterial-induced lung injury and endothelial cell rupture in part act through IL-33 to mediate increased vascular tone.

Maternal exercise represses FGF21 via SIRT1 to improve the phenotypic transformation of vascular smooth muscle in hypertensive offspring.

Maternal exercise during pregnancy is widely recognized as an effective means of promoting cardiovascular health in offspring. Few studies have explored how maternal exercise impacts vascular function and phenotypic switching in hypertensive offspring, despite the known involvement of vascular structural and functional remodeling in hypertension pathogenesis. Research indicates a significant relationship between elevated blood pressure and fibroblast growth factor 21 (FGF21) levels. It remains unclear whether maternal exercise during pregnancy can improve vascular function in hypertensive offspring by regulating FGF21 and its underlying mechanisms. In this study, pregnant spontaneously hypertensive rats and Wistar-Kyoto rats were randomly assigned to either a sedentary or exercise group. The exercise group underwent weightless swimming exercise from gestation day 1 (GD1) to GD20. The aim was to investigate the epigenetic modifications mediated by histone deacetylase sirtuin 1 (SIRT1) during the fetal period and the phenotypic changes in the mesenteric arteries (MAs) of hypertensive offspring. We found that maternal exercise significantly improved vascular remodeling in hypertensive offspring. Specifically, maternal exercise upregulated SIRT1 expression, which led to decreased H3K9ac (histone H3 lysine 9 acetylation) in the promoter region of the FGF21 gene. This epigenetic modification resulted in the transcriptional downregulation of FGF21 in the MAs of hypertensive fetuses. These results suggest that maternal exercise may lower blood pressure in hypertensive offspring by regulating deacetylation of the FGF21 gene promoter region through SIRT1, thereby reversing phenotypic switching and vascular structural remodeling.

A sex-dependent role of Kv1.3 channels from macrophages in metabolic syndrome

IntroductionCoronary artery disease (CAD) is the foremost single cause of mortality and disability globally. Patients with type 2 diabetes (T2DM) have a higher incidence of CAD, and poorer prognosis. The low-grade inflammation associated to T2DM contributes to increased morbidity and worst outcomes after revascularization. Inflammatory signaling in the vasculature supports endothelial dysfunction, leukocyte infiltration, and macrophage activation to a metabolic disease (MMe) specific phenotype, which could contribute to the metabolic disorders and ascular damage in T2DM. We have previously found that Kv1.3 blockers inhibit the development of intimal hyperplasia, thereby preventing restenosis. This inhibition was enhanced in a mouse model of T2DM, where systemic Kv1.3 blockers administration also improve metabolic dysfunction by acting on unidentified cellular targets other than vascular smooth muscle. Here we characterize the MMe phenotype in our T2DM model with a focus on macrophage Kv1.3 channels, to explore their contribution to vascular disease and their potential role as targets to ameliorate T2DM vascular risk.Methods and ResultsMale and female BPH mice fed on high-fat diet (HFD) develop metabolic syndrome (MetS) and T2DM. mRNA levels of several K+ channels (KV1.3, KCa3.1, Kir2.1) and macrophage markers (TNFα, NOS2, CD36) were analyzed. The MMe phenotype associated with increased CD36 expression. Channel-specific fingerprinting highlights a gender-specific increase of KV1.3 mRNA fold change in LPS stimulated macrophages from HFD compared to standard diet (SD). KV1.3 functional expression was also significantly increased after LPS stimulation in female HFD macrophages compared to SD. Functional studies showed that macrophage's KV1.3 channels of BPH female mice did not contribute to phagocytosis or metabolic profile but were relevant in cell migration rate.ConclusionAltogether, our data suggest that by inhibiting macrophage infiltration, Kv1.3 blockers could contribute to disrupt the vicious cycle of inflammation and insulin resistance, offering a novel approach to prevent MetS, T2DM and its associated cardiovascular complications in females.

Abstract 4135035: Liver kinase B1 (LKB1) loss links vascular smooth muscle cell fate switch to aortic aneurysm formation

Background: Acquisition and maintenance of vascular smooth muscle cell (VSMC) fate are important for vascular development and homeostasis; however, little is known about the key determinant for VSMC fate and vascular homeostasis. Methods: Lkb1 flox/flox ; Tagln- Cre, Lkb1 flox /flox ; Myh11-Cre/ERT2 , and lineage tracing Lkb1 flox/flox ; Myh11-Cre/ERT2 ; ROSA mT/mG mice were generated to study the impact of Lkb1 on VSMC and vascular function in vivo . Single aortic cells isolated from wild-type and Lkb1 flox/flox ; Myh11-Cre/ERT2 mice were analyzed by single-cell RNA sequencing (sc-RNA seq). The dynamic changes of vascular morphology and VSMC fate were investigated using high-frequency ultrasound and various histological techniques. In addition, VSMC phenotype and molecular mechanisms were further explored by mouse arterial ring assay ex vivo , in cultured human aortic VSMC in vitro, and in human aneurysmal aortic tissues. Results: We found that SMC-specific Lkb1 ablation in Lkb1 flox/flox ; Tagln-Cre mice caused severe vascular abnormalities and embryonic lethality. SMC-specific deletion of Lkb1 in tamoxifen-inducible Lkb1 flox/flox ; Myh11-Cre/ERT2 mice spontaneously and progressively induced aortic/arterial dilation, aneurysm, rupture, and premature death. Sc-RNA seq and imaging-based lineage tracing showed that Lkb1 -deficient VSMCs transdifferentiated gradually from early modulated VSMCs to fibroblast-like and chondrocyte-like cells, leading to ossification and blood-vessel rupture. Moreover, we found that SMC-specific Lkb1 ablation resulted in decreased vascular contractility and hypotension in vivo . Mechanistically, Lkb1 regulates polypyrimidine tract binding protein 1 (Ptbp1) expression and controls alternative splicing of pyruvate kinase muscle (PKM) isoforms 1 and 2. Lkb1 loss in VSMC results in an increased PKM2/PKM1 ratio and alters the metabolic profile by promoting aerobic glycolysis. Treatment with PKM2 activator TEPP-46 rescues VSMC transformation and aortic dilation in Lkb1 flox/flox ; Myh11-Cre/ERT2 mice. Furthermore, we found that Lkb1 expression decreased in human aortic aneurysm tissue compared to control tissue, along with changes in markers of VSMC fate. Conclusions: Lkb1, via its regulation of Ptbp1-dependent alterative splicing of PKM, maintains VSMC in contractile states and sustains vascular homeostasis. Our findings have important implications for understanding the pathogenesis of aortic aneurysm.

Abstract 4136598: Osteochondrogenic transdifferentiation of vascular smooth muscle cells and microenvironmental dynamics in medial arterial calcification at single-cell resolution

Background: Medial arterial calcification (MAC) significantly contributes to cardiovascular mortality, yet effective treatments remain limited due to unclear molecular mechanisms. This study aimed to develop a mouse model of MAC using O-ring-induced transverse aortic constriction (OTAC) and to elucidate key genes, pathways, and cellular interactions involved in MAC formation through lineage tracing and single-cell RNA sequencing (scRNA-seq). Methods: An OTAC mouse model was established to replicate MAC. Adult C57BL/6J male mice underwent OTAC, and subsequent analyses were conducted at various time points. Histological and immunohistochemical assessments were performed to monitor changes in vascular smooth muscle cells (VSMCs). Lineage tracing was utilized to verify the origin of osteochondrogenic VSMCs. Furthermore, scRNA-seq was employed to capture dynamic changes in VSMCs and other cell types contributing to MAC development. Results: The OTAC model successfully induced osteochondrogenic transdifferentiation of VSMCs, leading to MAC. Immunohistochemical analysis demonstrated time-dependent decreases in α-SMA expression and increases in SOX9 and RUNX2 expression. Lineage tracing using Myh11CreERT2;ROSA26-EGFP mice confirmed that osteochondrogenic VSMCs originated from contractile VSMCs. scRNA-seq identified osteochondrogenic VSMCs and revealed dynamic changes in surrounding cells, including macrophages and fibroblasts, which were implicated in calcification-related and inflammatory processes. Conclusion: The OTAC method effectively mimicked human MAC pathology, offering comprehensive insights into the microenvironmental dynamics of MAC progression at the single-cell level. This model serves as a robust platform for future research on therapeutic interventions.

Abstract 4119913: Aging-Associate Peptide Medin Induces Proinflammatory Activation in Human Brain Vascular Smooth Muscle Cells

Background: Medin is one of the most common amyloidogenic proteins and accumulates in the vasculature with aging. Vascular medin accumulation is associated with Alzheimer's disease, vascular dementia and aortic aneurysms. In vitro , medin has been shown to induce endothelial proinflammatory activation and in ex vivo human cerebral arterial tissue, medin induces both endothelial and smooth muscle dysfunction. The role of medin in vascular smooth muscle (VSMC) activation remains unknown. Aim: The aim of the study is to determine using gene transcription assay whether medin induces VSMC activation and phenotypic transformation. Methods: Human brain vascular smooth muscle cells (HBVSMCs, passages 6-10) were exposed to medin at doses observed in human tissues (0, 0.5, 1 and 5 υM) for 20 hours and reverse transcription polymerase chain reaction (rtPCR) was used to quantify gene expression of proinflammatory factors (interleukin (IL)-6, IL-8, IL-1b) and structural and enzyme proteins associated with VSMC phenotypic transformation (ACTA2, MYH11 and NOX4). In separate experiments, HBVSMCs were exposed to vehicle, medin 5 υM without or with small molecule NFκB inhibitor RO106-9920 (10 υM) or NLGM1 nanoliposome (70% phosphatidylcholine, 25% cholesterol, 5% monosialoganglioside, 100 υg/mL, agent shown to reverse medin-induced endothelial dysfunction and proinflammatory activation). Results: Medin induced a dose-dependent increase in gene expression of IL-6, IL-8 and IL-1b but did not alter gene expression of ACTA2, MYH11 and NOX4 (Fig. 1). Co-treatment of medin with RO106-9920 and NLGM1 showed a trend (not statistically significant) of reduced IL-6 and IL-8 (Fig. 2). Conclusions: Physiologic doses of medin induced pro-inflammatory activation of HBVSMCs but did not affect gene expression of structural proteins (ACTA2 and MYH11) and enzyme (NOX4) involved in VSMC phenotypic transformation. Although the mechanisms behind this effect remains to be explored, results suggest that medin may be an important mediator of aging-associated vascular inflammation.

Abstract 4124655: Multi-trait analysis identifies 307 genomic loci for thoracic aortic diameter and disease

Introduction: Thoracic aortic aneurysm and dissection (TAAD) is a morbid cardiovascular disease with 21 known common-variant genomic risk loci. Aneurysm represents an extreme of diameter, so we sought to jointly analyze TAAD and aortic diameter to enhance discovery power. Methods: Genome-wide association studies (GWAS) were performed for UK Biobank MRI-derived aortic diameter measured at the aortic root (N=62,919), ascending aorta (N=61,156), and descending aorta (N=62,412). Separately, TAAD GWAS summary statistics from UKB (1,076 cases, 416,263 controls), FinnGen (3,880 cases, 381,977 controls), and the Million Veteran Program (8,626 cases, 453,043 controls) were meta-analyzed. Genetic correlation was assessed with ldsc . Multi-trait analysis was then performed for the aortic measurements and TAAD with MTAG . A 1.1-million-variant polygenic risk score (PRS) was produced and tested in the All of Us biobank. Results: The genetic correlation between ascending aortic diameter and TAAD was 0.83 (P=6.6E-129). The TAAD meta-analysis had an effective sample size of 53,516, augmented to 147,377 after multi-trait analysis. We identified 59 risk loci for TAAD (189 in the multi-trait analysis). These loci included one on the X-chromosome near MIR222HG , previously reported to be regulated by angiopoietin-2; others were near TGF-β-superfamily members ( FBN1 , FBN2 , GDF6 , GDF7 , LTBP4 , TGFB2 , SMAD3 ); genes involved in vasoconstriction ( ADRA1D , ADRB1 , ANGPT1 , EDN1 , EDN2 , EDNRA , PDE3A ); and cell cycle regulators ( CCND2 , CCNE1 , CDC27 , CDK6 , CDKN1A , CDKN1B , CENPW , DSCC1 , MAD2L1 , TP53 ). 307 distinct loci were significantly associated with at least one of the four traits; all but 7 TAAD loci were genome-wide significant for one of the three aortic measurements, and all loci had at least sub-significant signal in those traits. Gene-set analyses highlighted contributions from fibroblasts, pericytes, and vascular smooth muscle cells. In All of Us , a one standard deviation (SD) greater PRS was associated with a hazard ratio (HR) of 1.88 for TAAD (P=1.2E-78) and 1.62 for thoracic aortic dissection (P=5.7E-05). Individuals in the top 5% for the PRS had HR 3.77 for TAAD (P=2.7E-48) and HR 2.87 for thoracic aortic dissection (P=3.3E-03). Discussion: The multi-trait analysis yielded an eight-fold expansion of loci for TAAD risk. The findings underscore that sporadic TAAD is a complex, common disease—intricately linked with the processes associated with normal variation in aortic diameter.

Evidence for Aldosterone Antagonism in Heart Failure

Activation of the renin–angiotensin–aldosterone system is the ultimate pathophysiological hallmark in heart failure. Though aldosterone primarily appears to regulate electrolyte homeostasis by acting on distal nephrons in the kidneys, its effects are far-reaching across the cardiovascular system as its receptors are also expressed in vascular smooth muscle cells, endothelial cells, macrophages and cardiomyocytes. Aldosterone excess leads to vascular stiffness, vasoconstriction, endothelial dysfunction, inflammation, oxidative stress, cardiac fibrosis and hypertrophy, atherogenesis and thrombosis. Hence, aldosterone antagonism is an attractive proposition for heart failure management. The first-generation non-selective mineralocorticoid receptor antagonist spironolactone produced a spectacular reduction of cardiovascular outcomes in the seminal RALES study, while the selective second-generation congener eplerenone boasts two positive studies: EPHESUS and EMPHASIS-HF. The TOPCAT trial indicated that a specific subgroup of patients with heart failure with preserved ejection fraction may benefit from targeted therapy of mineralocorticoid receptor antagonists. Newer-generation non-steroidal mineralocorticoid antagonists and aldosterone synthase inhibitors are being evaluated in randomised trials.

Abstract 4120749: GPR39 Orchestrates the Myogenic Response in Coronary Autoregulation

Background: Coronary autoregulation is the ability of a normal heart to maintain constant coronary blood flow (CBF) over a wide range of coronary driving pressures (CDPs) provided cardiac work remains constant. It is based on the myogenic response, the molecular mechanism of which is unknown. We recently described the presence of a G-protein coupled receptor (GPR39) in the vascular smooth muscle cells (VSMCs) of coronary arterioles in the mouse heart. We showed that endogenous eicosanoids, the vasoconstrictor 15-hydroxyeicosatetraenoic acid (15-HETE) and the vasodilator 14,15-epoxyeicosatrienoic acid (14,15 EET). act through this receptor to maintain coronary vascular tone. Hypothesis: We, therefore, hypothesized that GPR39 is the molecular switch responsible for the coronary myogenic response and autoregulation. Methods: We studied 6 anesthetized dogs at baseline and after administration of VC-108, a specific, potent GPR39 antagonist. Both during baseline and drug administration multiple coronary stenoses were created on the left anterior descending coronary artery (LAD). At each stage, heart rate, mean aortic pressure, distal LAD pressure, and right atrial pressure (RAP) were measured, as was CBF. Stenosis severity was defined by the CDP (LAD pressure minus RAP). Results: Mean basal coronary hyperemic response was 3.0 in all anesthetized animals indicating normal vasomotor function. Systemic hemodynamics did not differ between baseline and drug stages. Figure 1 is an example from a single dog where, at baseline, CBF remained constant over a CDP of 40-90 mm Hg indicating intact autoregulation. As expected, CBF declined when CDP fell below the autoregulatory range. After VC-108 administration CBF correlated linearly with CDP, indicating abolishment of the myogenic response. Baseline CDP vs. CBF data from all 6 animals within the autoregulatory range is depicted in Figure 2. No relation is noted between the two indicating intact autoregulation. In contrast, CDP vs. CBF relation is linear in all animals after VC108 is administered over the entire range of CDP’s measured, indicating abolishment of autoregulation (Figure 3). Conclusions: Our results indicate that GPR39 is a potential molecular switch for the regulation of the myogenic response underlying coronary autoregulation. Pharmacological blockage of GPR39 abolishes the myogenic tone. These novel findings set the stage for development of novel pharmacological agents for treatment of coronary artery disease.

Abstract 4117657: Targeting GPR39 for Hypoxia-induced Pulmonary Hypertension in Mice

Background: Primary pulmonary arterial hypertension (PAH) is a disease affecting young subjects. It has very poor prognosis and optimal treatment is not available. 15-hydroxyeicosatetraenoic acid (15-HETE), a potent vasoconstrictor, has been implicated in the pathogenesis of PAH. Elevated levels of 15-HETE have been shown to be associated with worse prognosis in patients with PAH. Oral ingestion of 15-HETE leads to development of PAH in rodents. We recently showed that 15-HETE is the endogenous agonist for the G-protein coupled receptor 39 (GPR39) present in vascular smooth muscle cells. Hypothesis: We, therefore, hypothesized that global deletion of GPR39 (knock-out [KO] mice) would protect from PAH by removing the receptor through which 15-HETE causes vasoconstriction. Methods: Accordingly, 13 wild-type (WT) and 16 KO mice were placed in a hypoxia chamber (10% O 2 ). Litter-mate controls (7 WT and 13 KO) were subjected to normoxia (room air, 21% O 2 ). At the end of 4 weeks heart rate as well as aortic and right ventricular (RV) pressures were measured (latter using micromanometer-tipped catheter), and the animals were then euthanized for measurement of RV wall thickness and RV size from which RV wall stress was calculated. Results: Heart rate and systolic blood pressure were not different between the 4 groups . WT hypoxic animals developed PAH with peak RV systolic pressures (RVSP) being significantly higher than normoxic WT and hypoxic WT and hypoxic KO mice. (Figure 1) Similar results were noted for RV end-diastolic pressure (Figure 2) and RV wall stress (Figure 3). Conclusions: By deleting GPR39, the target for 15-HETE, we were able to prevent hypoxia induced PAH and RV dysfunction. Pharmacological inhibition of GPR39 may open new frontiers in the treatment of PAH.

Abstract 4136905: EF-24, a curcumin analog, reverses interleukin-18-induced miR-30b or miR-342-dependent TRAF3IP2 expression, RECK suppression, and the proinflammatory phenotype of human aortic smooth muscle cells

Curcumin, a polyphenolic compound derived from the widely used spice Curcuma longa, has shown anti-atherosclerotic effects in cultured vascular cells and animal models. We previously reported that the induction of the proinflammatory molecule TRAF3IP2 (TRAF3 Interacting protein 2) or inhibition of the matrix metalloproteinase (MMP) regulator RECK (Reversion Inducing Cysteine Rich Protein with Kazal Motifs) contributes to agonist-induced proinflammatory, pro-oxidant, pro-mitogenic and pro-migratory effects in vascular smooth muscle cells. Here we hypothesized that, EF-24 ((3E,5E)-3,5-bis[2-fluorophenyl (methylene]-4piperidinone), a curcumin analog with better bioavailability and potency, reverses interleukin (IL)-18-induced TRAF3IP2 induction, RECK suppression and the proinflammatory phenotype of primary human aortic smooth muscle cells (ASMC). Exposure to recombinant human IL-18 (10 ng/ml) induced TRAF3IP2 mRNA and protein expression, but markedly suppressed RECK in a time-dependent manner. Further investigations revealed that IL-18 induced miR-30b, but suppressed miR-342, in a p38 MAPK and JNK-dependent manner. While miR-30b inhibitor blunted IL-18-induced TRAF3IP2 expression, miR-30b inhibitor and miR-342 mimic each restored RECK expression. Further, IL-18 induced ASMC migration (Boyden chamber assay) and proliferation (CyQUANT Cell Proliferation assay), and these effects were reversed by TRAF3IP2 knockdown or RECK overexpression. Our results also show that IL-18 induced MMP2 and MMP9 expression and activity, and targeting their expression inhibited IL-18-induced ASMC migration. TRAF3IP2 knockdown or RECK overexpression also reversed IL-18-induced ASMC proinflammatory phenotype switching as evidenced by the enhanced expression of the SMC markers ACTA2 and MYH11, and reduced expression of the proinflammatory markers Galectin 3, Olr1, VCAM, CCL2, IL-6, IL-8, and TNF-α. Importantly, preincubation with EF-24 markedly suppressed IL-18-induced SMC proliferation, MMP expression, migration and the proinflammatory phenotype switching. Together, these results suggest that the curcumin analog EF-24 has therapeutic potential in vascular inflammatory and proliferative diseases, including atherosclerosis, by differentially regulating TRAF3IP2 and RECK in vascular SMC.

Abstract 4113617: Single-cell Analysis Reveals Endothelial Cell CD45 Deficiency Prevents Endothelial-to-Mesenchymal Transition (EndMT) in Atherosclerosis

Introduction: Protein-tyrosine-phosphatase CD45 is exclusively expressed in all nucleated cells of the hematopoietic system but is rarely expressed in endothelial cells (ECs). However, a recent study indicated that activation of the endogenous CD45 promoter in human endothelial colony forming cells induced expression of EndMT marker genes. Also, the CD45 phosphatase inhibitor blocked EndMT activities in TGFβ1-treated ovine mitral valve endothelial cells. EndMT contributes to atherosclerotic pathobiology and is associated with more complex plaques. We identified CD45-positive ECs undergoing EndMT in atherosclerotic ApoE-deficient (ApoE -/- ) mice. Here, we aim to investigate whether endothelial CD45-specific deletion can prevent EndMT in a mouse model of atherosclerosis. Methods and Results: We generated a tamoxifen-inducible EC-specific CD45-deficient mouse strain (EC-iCD45KO) on an ApoE -/- background (C57BL/6) and fed these mice a Western diet for 16 weeks. We isolated and enriched mouse aortic endothelial cells with CD31 beads to perform single-cell RNA-seq. Cells populated 15 major clusters after integrating the single-cell transcriptomic profiles. In the EC-iCD45KO group, the population of endothelial, resident macrophage, and mesenchymal-endothelial transition cells increased while vascular smooth muscle, EndMT, and fibroblast cells decreased. In EndMT cells, EC markers (Cdh5, Cldn5, Pecam1) increased, but SMC markers (Acta2) and EndMT markers (Col1a2 and Col3a1）decreased. In addition, we characterized EndMT cells into two sub-clusters: 1 and 2. EC-specific CD45 deletions reduced the cell numbers in the EndMT2 sub-cluster in atherosclerotic mice but had less impact on the EndMT1 sub-cluster. FGFR pathways were potentiated while TGFβ1 and Tgfbr2 decreased in EndMT1 sub-cluster， and the genes controlling endothelial cell development were upregulated but the genes controlling actin cytoskeleton organization were downregulated in both EndMT1 and 2 sub-clusters. Conclusion: Our single-cell analysis indicates that the loss of endothelial CD45 protects against EndMT-driven atherosclerosis, inhibiting TGFβ and EndoMT marker expression while stimulating FGFR pathways. Consistently, EC-iCD45KO/ApoE -/- mice showed reduced plaque macrophages, expression of cell adhesion molecules, foam cell formation, and lesion development when compared to ApoE -/- controls. Thus, targeting endothelial CD45 may be a novel therapeutic strategy for EndMT and atherosclerosis.

Abstract 4137846: Smooth muscle expression of RNA editing enzyme ADAR1 controls vascular integrity and progression of atherosclerosis

Mapping the genomic architecture of complex disease has been predicated on the understanding that genetic variants influence disease risk through modifying gene expression. However, recent discoveries have revealed that a significant burden of disease heritability in common autoinflammatory disorders and coronary artery disease is mediated through genetic variation modifying post-transcriptional modification of RNA through adenosine-to-inosine (A-to-I) RNA editing. This common RNA modification is catalyzed by ADAR enzymes, where ADAR1 edits specific immunogenic double stranded RNA (dsRNA) to prevent activation of the double strand RNA (dsRNA) sensor MDA5 ( IFIH1 ) and stimulation of an interferon stimulated gene (ISG) response. Multiple lines of human genetic data indicate impaired RNA editing and increased dsRNA sensing to be an important mechanism of coronary artery disease (CAD) risk. Here, we provide a crucial link between observations in human genetics and mechanistic cell biology leading to progression of CAD. Through analysis of human atherosclerotic plaque, we implicate the vascular smooth muscle cell (SMC) to have a unique requirement for RNA editing, and that ISG induction occurs in SMC phenotypic modulation, implicating MDA5 activation. Through culture of human coronary artery SMCs, generation of a conditional SMC specific Adar1 deletion mouse model on a pro-atherosclerosis background, and with incorporation of single cell RNA sequencing cellular profiling, we further show that Adar1 controls SMC phenotypic state, is required to maintain vascular integrity, and controls progression of atherosclerosis and vascular calcification. Our data implicates MDA5 activation to occur in SMC phenotypic modulation and accelerates formation of chondromyocytes in a distinct cellular lineage trajectory — indicating a cell type and context specific requirement of RNA editing. Through this work, we describe a fundamental new mechanism of CAD, where RNA editing and sensing of dsRNA in a cell type and context specific mechanism mediates disease progression, bridging our understanding of human genetics and disease causality.

Abstract 4119262: Anti-atherosclerotic Potential of M2 Macrophage-Derived Exosomes by Promoting Cholesterol Efflux of Foam Cell-Like Vascular Smooth Muscle Cells via the PPARγ-LXRα-ABCA1/ ABCG1 Pathway

Background: Impediment in the excretion of lipid deposits within SMC-derived foam cells (SMC-FCs) is one of the reasons for the continuous expansion of the plaque necrotic core. This study aims to explore the effect and underlying mechanimsm of exosomes secreted by M2 macrophage (M2-exos) on SMC-FCs lipid metabolism and plaque stability. Methods: First, immunofluorescence was used to detect the expression levels of CD45 (a recognized differentially expressed molecule of myeloid and SMC-FCs) and the key proteins of cholesterol efflux pathway, ABCA1 and ABCG1, in human early and late plaques. Exosomes derived from M0 and M2 macrophages were purified by sucrose density gradient centrifugation, and characterized based on specific morphology and surface markers. Western blot, Oil red O staining and cell total cholesterol assay were used to assess the effects of M2-exos on the lipid mechanism of SMC-FCs. RNA-seq was used to detect the miRNA profiles of M2-exos. Quantitative real-time PCR was used to identify candidate miRNAs. The dual-luciferase reporting system was utilized to assess the regulatory effect of candidate miRNA on target gene. Then, the effect of M2-exos on the progression and stability of plaques in ApoE -/- mice was evaluated using Oil red O, H&amp;E, Masson, Movat and immunohistochemistry. Results: Immunofluorescence revealed that compared with early plaques, VSMC-FCs (CD45 - ) were significantly increased in late plaques, and the expression levels of ABCG1 and ABCA1 were marked lower than those in macrophage-derived foam cells (CD45 + ). Purified M2-exos treatment significantly promoted the cholesterol efflux of SMC-FCs in vitro. In high-fat-fed ApoE -/- mice, M2-exos significantly reduced the VSMC-FCs, delayed the progression of plaques, decreased necrotic core area and enhanced plaque stability. MiRNA profiling and comprehensive analysis of signaling pathways showed that M2-exos were rich in miR-7683-3p, which played a key role in regulating SMC-FCs lipid metabolism through PPARγ-LXRα-ABCA1/ABCG1 pathway. Dual-luciferase reporting assay showed that miR-7683-3p can specifically bind to the promoter region of homeobox genes A1(HoxA1), an inhibitor of PPARγ-LXRα-ABCA1/ABCG1 pathway. Conclusion: M2-exos exerted an obvious atherosclerotic protective effect, and the underlying mechanism was closely related to MiR-7683-3p, which targeted the 3’UTR of HoxA1 mRNA and activated the PPARγ-LXRα-ABCA1/ABCG1 mediated cholesterol efflux in SMC-FCs.

Abstract 4137257: Hepatocyte growth factor -mediated Angiogenesis supersession in Hyperhomocysteinemia

Background: Homocysteine (Hcy) is a well-established cardiovascular risk factor. Elevated homocysteine, or hyperhomocysteinemia (HHcy), inhibit the growth of endothelial cells and stimulate vascular smooth muscle cell proliferation. However, the mechanisms of HHcy disrupts angiogenesis remain unclear. Here we examine the molecular pathways involved in HHcy-impaired angiogenesis. Method: We generated Tg-hCBS+ Cbs-/- mice by crossing Cbs knockout mice and Tg-hCBS mice where human CBS cDNA was regulated by a zinc-inducible metallothionein promoter. The model exhibited severe HHcy (＞115 μmol/L). We conducted both in vivo and in vitro experiments, including vasculogenesis assays of retinal and heart tissues, aortic ring assay, and tube formation. Retinas were stained with Isolectin B4 and imaged using a confocal microscope. The Human Angiogenesis RT 2 Profiler™ PCR Array was used to profile 84 key angiogenesis-related genes. Homocysteine metabolites in Cbs mice were measured by HPLC. ChIP-seq data were analyzed using Chip Atlas. Additionally, 91 patients went through coronary angiography were enrolled from the Second Affiliated Hospital of Nanchang University. Participants with CTFC, greater than 27 frames per second were identified as having slow coronary arteries flow (SCF). Results: HHcy caused SCF in patients and impaired vasculogenesis in the retinas of newborn and 12-week-old Tg-hCBS Cbs-/- mice. Capillary density in the hearts of adult Tg-hCBS Cbs-/- mice was reduced. HHcy suppressed tube formation and aortic ring microvessel growth in a concentration-dependent manner. The PCR array revealed significant gene expression changes in Hcy treated human aortic endothelial cells. Notably, genes encoding hepatocyte growth factor (HGF), collagen type IV alpha 3, epiregulin, interferons, and leukocyte cell-derived chemotaxin 1 were downregulated by at least four-fold. In an acute myocardial infarction model, HGF expression was further reduced, and HGF treatment rescued Hcy-inhibited tube formation and microvessel growth. Hcy and S-adenosylhomocysteine levels were negatively correlated with plasma HGF levels. ChIP-seq data identified homocysteine-responsive hypomethylation in ETF, TFII, FOXP3, RXRa, and c-Jun Hcy-hypomethylation Box (-2701/0). Conclusion: HHcy impair angiogenesis via HGF inhibition, which has a rescue effect. Hypomethylation caused by Hcy affects the methylation status of specific CpG sites within the Hcy-hypomethylation box of the HGF gene.