Adverse Vascular Remodeling Research Articles

Abstract 9929: Epigenome-Wide-Association-Study Characterizes DNA Methylation Changes Associated With Lung and Right Ventricle Dysfunction in Pulmonary Hypertension

Background: Pulmonary arterial hypertension (PAH) is a lethal vasculopathy associated with pulmonary arteries remodeling and right ventricle (RV) dysfunction. Epigenetic dysregulation, including altered DNA methylation (DNAm), promotes PAH. However, the DNAm changes associated with PAH remain unexplored in human PAH RV and lungs. We conducted an exploratory study using human lung and RV samples to characterize the DNA methylome and transcriptomic changes associated with PAH. Methods/Results: We observed that PAH is associated with substantial changes in the DNAm landscape in both organs. We identified 88 identical differentially methylated probe (DMP) in both PAH Lungs and RV. Functionally, we observed that 65, and 76 of those DMP correlate with myocardial fibrosis and adverse pulmonary vascular remodeling, respectively. Then we clustered DMP onto functional differentially methylated region (DMR) and reported that 41% and 11.5% of the genes carrying a DMR are differentially expressed in PAH RV and lungs, respectively. Gene ontology analysis suggests that both impaired DNAm (DNA methylome) and genes expression (RNA sequencing) observed in PAH regulate biological functions related to inflammation, fibrosis, cell proliferation and vascular remodeling. Impaired DNAm landscape observed in PAH RV and lung is associated with the disease severity and contributes to 4.1% and 2.7% of the whole transcriptomic reprograming associated with PAH development in RV and lungs samples, respectively. Despite the modest overlap between DNAm and transcriptomic changes, we observed that DNAm affects genes and molecular pathways involved in PAH development. Conclusion: Although exploratory, our study is the first to characterize the DNAm and transcriptomic change associated with PAH in human RV and lung. Our data suggest that impaired DNAm landscape might contribute to the disease development/severity.

Inhibition of neointimal hyperplasia in balloon-induced vascular injuries in a rat model by miR-22 loading Laponite hydrogels

Percutaneous coronary intervention (PCI) is the mainstream treatment to widen narrowed or obstructed coronary arteries due to pathological conditions. However, the post-operational neointimal hyperplasia occurs because of endothelium denudation during surgical procedures and the following inflammation. MicroRNAs (miRs) are new therapeutics of great potential for cardiovascular diseases. However, miRs easily degrade in vivo. A vehicle that can maintain their bioactivities and extend their retention at the site of delivery is prerequisite for miRs to play their roles as therapeutic reagents. Here, we reported the use of the Laponite hydrogels to deliver miR-22 that are modulators of phenotypes of smooth muscle cells (SMCs). The Laponite hydrogels allow a homogenous distribution of miR-22 within the gels, which had the capacity to transfect SMCs in vitro. Upon the injection of the miR-22 incorporated in the Laponite hydrogels in vivo, miR-22 could be well retained surrounding arteries for at least 7 days. Moreover, the miR-22 loading Laponite hydrogels inhibited the neointimal formation, reduced the infiltration of the macrophages, and reversed the adverse vascular ECM remodeling after the balloon-induced vascular injuries by upregulation of miR-22 and downregulation of its target genes methyl-CpG binding protein 2 (MECP2). The application of the Laponite hydrogels for miR local delivery may offer a novel strategy to treat cardiovascular diseases.

Apelinergic System: an in‐vitro Investigation of Inflammatory & Oxidative Stress in Chronic Kidney Disease

Over 37 million US adults have Chronic Kidney Disease (CKD). Of that population–35% are Black. With 4x higher predisposition to developing renal failure due to comorbidities (i.e. hypertension and diabetes), there is a dire need to address both preventative and therapeutic options in this population. Besides dialysis and transplant as reactionary treatments of CKD, vitamin E—an antioxidant—has been given to those in late stage CKD. Our study aims to address mechanisms behind CKD pathology. The 5/6 nephrectomy (5/6Nx) rat CKD model provides the opportunity to isolate the effects of impaired renal function without significant confounding comorbidities. A hallmark feature of both rat and human CKD is adverse vascular remodeling which is often preceded by endothelial cell (EC) dysfunction. With respect to EC dysfunction, inflammatory and oxidative imbalances are suspected to be involved. Our previous transcriptomic analysis of kidney tissues from the 5/6Nx rat identified a significant increase in apelin receptor (APLNR) expression compared to sham controls. In addition, the data revealed several pro‐inflammatory cytokines (IL‐6 and IL‐1β) preceding APLNR transcript increases. Treatment of Normal Rat Kidney epithelial (NRK) cells with IL‐6 caused a significant reduction in apelin (APLN) ligand, while IL‐1β augmented APLNR transcript levels. After further study of the 3 pathways, a common downstream target, protein kinase B (AKT), arose. Interestingly enough, AKT is responsible for various vascular cascades including interaction with well‐known reactive oxygen species (ROS) producer–NADPH Oxidase 4 (NOX4). Hydrogen Peroxide (H2O2), a ROS product of NOX4, coordinates vasoactivity through AKT signaling and has overlapping function with apelinergic (APJ) system in the vasculature. Due to the inflammatory and oxidative nature of CKD, we want to address the relationship between H2O2 and the APJ system. We hypothesize that pretreating NRK cells with APLN prior to administration of H2O2 will have 2 effects: oxidant attenuation and antioxidant augmentation. NRK cells were pretreated with 2.5ng/mL apelin or 30mg/mL vitamin E 48‐hours prior to addition of 20mM H2O2. At study termination, cells were collected/quantified using the Bradford protein assay. Protein expression was measured via Western blots against catalase, an antioxidant marker, and GPx, an oxidant protein. One‐Way ANOVA and Tukey Post‐Hoc test were used to establish statistical significance (p<0.05). Catalase: no significant expression changes after APLN or vitamin E treat (p = 0.10), but significant increases after H2O2 treat (p = 0.05) compared to control. GPx: significant increases in expression after APLN treat compared to [control (p=0.0002), vitamin E (p=0.04), and H2O2 + APLN (p=0.0001)] and vitamin E compared to H2O2 + Vitamin E treat (p=0.01). Data presented as mean ± SEM (n=3). These studies assessed functionality of the APJ system in an in‐vitro model of CKD. Both of the inflammatory cytokines are regulators of APJ system transcription, which is relevant for patients in a chronic inflammatory state. These studies also highlight the interaction between APJ system and oxidative stressors. Results here begin to lay the foundation for future studies involving the APJ system as a viable target for assessing CKD pathology.

Inhibition of sphingomyelinase attenuates diet – Induced increases in aortic stiffness

Sphingomyelinases ensure ceramide production and play an integral role in cell turnover, inward budding of vesicles and outward release of exosomes. Recent data indicate a unique role for neutral sphingomyelinase (nSMase) in the control of ceramide-dependent exosome release and inflammatory pathways. Further, while inhibition of nSMase in vascular tissue attenuates the progression of atherosclerosis, little is known regarding its role on metabolic signaling and arterial vasomotor function. Accordingly, we hypothesized that nSMase inhibition with GW4869, would attenuate Western diet (WD) - induced increases in aortic stiffness through alterations in pathways which lead to oxidative stress, inflammation and vascular remodeling. Six week-old female C57BL/6L mice were fed either a WD containing excess fat (46%) and fructose (17.5%) for 16 weeks or a standard chow diet (CD). Mice were variably treated with GW4869 (2.0 μg/g body weight, intraperitoneal injection every 48 h for 12 weeks). WD feeding increased nSMase2 expression and activation while causing aortic stiffening and impaired vasorelaxation as determined by pulse wave velocity (PWV) and wire myography, respectively. Moreover, these functional abnormalities were associated with aortic remodeling and attenuated AMP-activated protein kinase, Sirtuin 1, and endothelial nitric oxide synthase activation. GW4869 treatment prevented the WD-induced increases in nSMase activation, PWV, and impaired endothelium dependent/independent vascular relaxation. GW4869 also inhibited WD–induced aortic CD36 expression, lipid accumulation, oxidative stress, inflammatory responses, as well as aortic remodeling. These findings indicate that targeting nSMase prevents diet – induced aortic stiffening and impaired vascular relaxation by attenuating oxidative stress, inflammation and adverse vascular remodeling.

Association of Circulating miR-145-5p and miR-let7c and Atherosclerotic Plaques in Hypertensive Patients

Aim: Hypertension is a strong risk factor for atherosclerosis. Increased carotid intima-media thickness (cIMT) and carotid plaques are considered subclinical markers of atherosclerosis. This study aimed at evaluating the serum expression of miRNAs previously related to adverse vascular remodeling and correlating them with carotid plaques and cIMT in hypertensive patients. Methods: We cross-sectionally evaluated the clinical and carotid characteristics as well as serum expression of miR-145-5p, miR-let7c, miR-92a, miR-30a and miR-451 in 177 hypertensive patients. Carotid plaques and cIMT were evaluated by ultrasound, and the expression of selected miRNAs was evaluated by a quantitative polymerase chain reaction. Results: Among all participants (age = 60.6 ± 10.7 years, 43% males), there were 59% with carotid plaques. We observed an increased expression of miR-145-5p (Fold Change = 2.0, p = 0.035) and miR-let7c (Fold Change = 3.8, p = 0.045) in participants with atherosclerotic plaque when compared to those without plaque. In the logistic regression analysis adjusted for relevant covariates, these miRNAs showed a stronger association with carotid plaques (miR-145-5p: Beta ± SE = 0.050 ± 0.020, p = 0.016 and miR-let7c: Beta ± SE = 0.056 ± 0.019, p = 0.003). Conclusions: Hypertensive patients with carotid plaques have an increased expression of miR-145-5p and miR-let7c, suggesting a potential role of these miRNAs as a biomarker for subclinical atherosclerosis in hypertensive individuals.

Overexpression of dimethylarginine dimethylaminohydrolase 1 protects from angiotensin II-induced cardiac hypertrophy and vascular remodeling.

Cardiovascular complications are the leading cause of death, and elevated levels of asymmetric dimethyarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, are implicated in their pathophysiology. We investigated the role of dimethylarginine dimethylaminohydrolase 1 (DDAH1), an enzyme hydrolyzing ADMA, in prevention of cardiovascular remodeling during hypertension. We hypothesized that the animals overexpressing DDAH1 will be protected from angiotensin II (ANG II)-induced end organ damage. Angiotensin II (ANG II) was infused in two doses: 0.75 and 1.5 mg/kg/day in DDAH1 transgenic mice (DDAH1 TG) and wild-type (WT) littermates for 2 or 4 wk. Echocardiography was performed in the first and fourth weeks of the infusion, systolic blood pressure (SBP) was measured weekly, and cardiac hypertrophy and vascular remodeling was assessed by histology. Increase in SBP after 1 wk of ANG II infusion was not different between the groups, whereas TG mice had lower SBP at later time points. TG mice were protected from cardiovascular remodeling after 2 wk of ANG II infusion in the high dose and after 4 wk in the moderate dose. TG mice had higher left ventricular lumen-to-wall ratio, lower cardiomyocyte cross-sectional area, and less interstitial fibrosis compared with WT controls. In aorta, TG mice had less adventitial fibrosis, lower medial thickness with preserved elastin content, lower counts of inflammatory cells, lower levels of active matrix metalloproteinase-2, and showed better endothelium-dependent relaxation. We demonstrated that overexpression of DDAH1 protects from ANG II-induced cardiovascular remodeling and progression of hypertension by preserving endothelial function and limiting inflammation.NEW & NOTEWORTHY We showed that overexpression of dimethylarginine dimethylaminohydrolase 1 (DDAH1) protects from angiotensin II-induced cardiovascular damage, progression of hypertension, and adverse vascular remodeling in vivo. This protective effect is associated with decreased levels of asymmetric dimethylarginine, preservation of endothelial function, inhibition of cardiovascular inflammation, and lower activity of matrix metalloproteinase-2. Our findings are highly clinically relevant, because they suggest that upregulation of DDAH1 might be a promising therapeutic approach against angiotensin II-induced end organ damage.

Molecular genetic evaluation of pediatric renovascular hypertension due to renal artery stenosis and abdominal aortic coarctation in neurofibromatosis type 1.

The etiology of renal artery stenosis (RAS) and abdominal aortic coarctation (AAC) causing the midaortic syndrome (MAS), often resulting in renovascular hypertension (RVH), remains ill-defined. Neurofibromatosis type 1 (NF-1) is frequently observed in children with RVH. Consecutive pediatric patients (N = 102) presenting with RVH secondary to RAS with and without concurrent AAC were prospectively enrolled in a clinical data base, and blood, saliva and operative tissue, when available, were collected. Among the 102 children, 13 were having a concurrent clinical diagnosis of NF-1 (12.5%). Whole exome sequencing was performed for germline variant detection, and RNA-Seq analysis of NF1, MAPK pathway genes and MCP1 levels were undertaken in five NF-1 stenotic renal arteries, as well as control renal and mesenteric arteries from children with no known vasculopathy or NF-1. In 11 unrelated children with sequencing data, 11 NF1 genetic variants were identified, of which 10 had not been reported in gnomAD. Histologic analysis of NF-1 RAS specimens consistently revealed intimal thickening, disruption of the internal elastic lamina and medial thinning. Analysis of transcript expression in arterial lesions documented an approximately 5-fold reduction in NF1 expression, confirming heterozygosity, MAPK pathway activation and increased MCP1 expression. In summary, NF-1-related RVH in children is rare but often severe and progressive and, as such, important to recognize. It is associated with histologic and molecular features consistent with an aggressive adverse vascular remodeling process. Further research is necessary to define the mechanisms underlying these findings.

Single-cell RNA-seq reveals a critical role of novel pro-inflammatory EndMT in mediating adverse remodeling in coronary artery-on-a-chip.

A three-dimensional microengineered human coronary artery-on-a-chip was developed for investigation of the mechanism by which low and oscillatory shear stress (OSS) induces pro-atherogenic changes. Single-cell RNA sequencing revealed that OSS induced distinct changes in endothelial cells (ECs) including pro-inflammatory endothelial-to-mesenchymal transition (EndMT). OSS promoted pro-inflammatory EndMT through the Notch1/p38 MAPK-NF-κB signaling axis. Moreover, OSS-induced EC phenotypic changes resulted in proliferation and extracellular matrix (ECM) protein up-regulation in smooth muscle cells (SMCs) through the RANTES-mediated paracrine mechanism. IL-37 suppressed OSS-induced pro-inflammatory EndMT and thereby abrogated SMC proliferation and ECM protein remodeling. Overall, this study provides insights into endothelial heterogeneity under atheroprone shear stress and identifies the mechanistic role of a novel EC subtype in promoting adverse vascular remodeling. Further, this study demonstrates that anti-inflammatory approach is capable of mitigating vascular pathobiology evoked by atheroprone shear stress.

Preclinical Evaluation of the Temporary Drug-Coated Spur Stent System in Porcine Peripheral Arteries

Background: Drug penetration into the deeper arterial wall of heavily calcified lesions is one of the limitations of drug-coated balloons and drug-eluting stents in vascular interventions. The Temporary Spur Stent (TSS) system is characterized by a self-expanding nitinol stent that is uniformly covered in radialspikes, which, when coated, should allow a deeper penetration and longer retention of the drug into the diseased artery walls by penetrating through the calcified plaques. Materials and Methods and Results: Uncoated TSS and paclitaxel (PTX)-coated TSS systems have been deployed in porcine peripheral arteries. Four weeks after the deployment of uncoated TSS systems, no adverse vascular remodeling or neointimal formation in the treated vessel segments were noticed. PTX-coated TSS systems transferred 9%±7% of the drug that was on the device to the targeted vessel area (196±163 ng PTX/mg arterial tissue) and the addition of the fluorescent dye Nile red to the coating showed that the spikes promote the transfer of the coating to the deeper layers of the vessel wall. The PTX-coated TSS systems showed a significant reduction in neointimal proliferation compared to the uncoated TSS systems: quantitative angiography showed a vessel diameter stenosis of 37.2%±11.0% and 16.4%±8.8% 4 weeks after the treatment with uncoated and PTX-coated TSS systems, respectively. Conclusion: The treatment with the TSS system was well tolerated and the spikesfacilitate the transfer of the coating into deeper layers of the vessel wall. Moreover, the PTX-coated TSS systems effectively inhibit neointimal proliferation.

Stimulator of Interferon Genes (STING) regulates Re‐endothelialization Following Vascular Injury

Percutaneous coronary interventions (PCI) are commonly used to improve blood flow in Peripheral Artery Disease. Complications of PCI are delayed re-endothelialization and endothelial cell (EC) dysfunction leading to adverse clinical outcomes. Stimulator of Interferon Genes (STING), canonically activated downstream of the cGAS enzyme, is a signaling hub molecule modulating immune responses triggered by self-derived and/or foreign DNA. We hypothesized that EC-intrinsic STING regulates re-endothelialization in response to vascular injury. We modeled PCI in WT, STING-/-, and in a newly generated inducible vascular EC- specific mouse (VECad5Cre-ERT2STINGfl/fl mice: EC-STING-/-) using the wire induced carotid injury model. We used Evans Blue Dye injection post injury to identify the areas denuded of EC and quantified the % of non-blue (re-endothelialized) area. We found that WT mice had complete re-endothelialization five days post injury (95.16 ± 2.77 %). In contrast, injured carotid arteries in STING-/- mice exhibited a decrease in re-endothelialization at the same timepoint (43.57 ± 9.79%). Moreover, EC-STING-/- mice recapitulated the delayed re-endothelialization (10.45 ± 1.56% in Tamoxifen treated mice to induce excision of STING in EC, compared to 40 ± 1.28% observed in vehicle treated VECad5Cre-ERT2STINGfl/fl control mice 5 days post scratch) in the injured arteries, supporting a role of EC STING in re-endothelialization post injury. To further investigate this EC-specific effect of STING mechanistically in vitro, we performed scratch assays on WT and STING mouse heart EC (MHEC) monolayers, as well as on human EC monolayers lacking STING after CRISPR knock down and imaged wound healing in real time by IncuCyte. WT MHEC and HUVEC completely covered the scratch area within 24 hours, and 4 hours, respectively, whereas both EC lacking STING were delayed healing the scratch. Additionally, we found that the healing response was independent of cGAS, since cGAS KD HUVEC had similar post- scratch recovery time as control HUVEC. Ongoing experiments investigate the mechanisms involved in this novel STING dependent, cGAS-independent pathway of EC response to injury, as well as the consequences of EC-STING in adverse chronic vascular remodeling.

LOW-DOSE FOLIC ACID PROTECTS AGAINST ADVERSE CARDIAC REMODELING IN SPONTANEOUSLY HYPERTENSIVE RATS WITH HYPERHOMOCYSTEINEMIA

Objective: The interaction between hypertension and hyperhomocysteinemia (Hhcy) leads to adverse myocardial and coronary vascular remodeling in the hypertensive heart, resulting in impaired diastolic function. Folic acid (FA) is a free radical scavenger with antioxidant properties that effectively reduces homocysteine (Hcy) levels. The aim of this study was to evaluate whether lowering plasma homocysteine (Hcy) with different dose of folic acid (FA) could against Hhcy-induced myocardial injury in spontaneously hypertensive rats (SHRs) and its possible mechanisms. Design and method: Thirty-two adult male SHRs were randomly divided into four groups (n = 8/group), namely control group, Hhcy intervention group, Hhcy + Low-dose FA treatment group (0.4 mg/Kg·d), Hhcy + High-dose FA treatment group (4 mg/Kg·d), and then three Hhcy groups were subcutaneously injected 2% DL- homocysteine 5 ml/Kg. FA intervention started after 4 weeks’ Hcy injection. The total duration of the trial was 16 weeks. Cardiac echocardiography was performed at the last week. The Systolic blood pressure (SBP), diastolic blood pressure (DBP), plasma Hcy, serum malondialdehyde (MDA), superoxide dismutase (SOD) were measured, and Masson's trichrome stain to enable evaluation of collagen deposition under a microscope. Furthermore, the levels of nuclear factor (erythroid-derived 2)-like 2 (Nrf2) and heme oxygenase 1 (HO-1) protein were detected by extraction of nuclear protein from cardiac tissue. Results: Intragastric administration of FA significantly reduced plasma Hcy levels. Serum SOD was significantly increased and serum MDA were also significantly attenuated by FA. Low-dose folic acid is more effective than high-dose folic acid in relieving Hhcy-induced anomalies in the heart of SHRs, such as the decline in cardiac diastolic function, perivascular collagen accumulation, and arteriolar wall thickening. FA increased the expression of Nrf2 and HO-1, and exhibited a protective effect against Hhcy-induced oxidative stress (OS), and there were no significant difference between high-dose and low-dose FA groups. Conclusions: Low-dose FA treatment can better protect against Hhcy-induced myocardial injury in SHRs, which may be due to its inhibition of OS and upregulation of Nrf2/HO-1 pathway.

ECM2 and GLT8D2 in human pulmonary artery hypertension: fruits from weighted gene co-expression network analysis.

BackgroundPulmonary artery hypertension (PAH) is an incurable disease with a high mortality rate. Current medications ameliorate symptoms but cannot target adverse vascular remodeling. New therapeutic strategies for PAH need to be established.MethodsUsing the weighted gene coexpression network analysis (WGCNA) algorithm, we constructed a coexpression network of dataset GSE117261 from the Gene Expression Omnibus (GEO) database. Key modules were identified by the relationship between module eigengenes and clinical traits. Hub genes were screened out based on gene significance (GS), module membership (MM), and mean pulmonary artery pressure (mPAP). External validations were conducted in GSE48149 and GSE113439. Functional enrichment and immune cell infiltration were analyzed using Metascape and CIBERSORTx.ResultsThe WGCNA analysis revealed 13 coexpression modules. The pink module had the highest correlation with PAH in terms of module eigengene (r=0.79; P=2e−18) and module significance (MS =0.43). Functional enrichment indicated genes in the pink module contributed to the immune system process and extracellular matrix (ECM). In the pink module, ECM2 (GS =0.65, MM =0.86, ρ=0.407, P=0.0019) and GLT8D2 (GS =0.63, MM =0.85, ρ=0.443, P=0.006) were identified as hub genes. For immune cells infiltration in PAH lung tissue, hub genes were positively correlated with M2 macrophages and resting mast cells, and were negatively correlated with monocytes, neutrophils, and CD4-naïve T cells.ConclusionsOur research identified 2 hub genes ECM2 and GLT8D2 related to PAH. The functions of these hub genes were involved in the immune process and ECM, indicating that they might serve as candidate therapeutic targets for PAH.

HYPERTENSION DURING EARLY PREGNANCY IMPAIRS GENETIC PRIMING OF UTERINE ARTERIES PRIOR TO REMODELLING IN RODENTS

Objective: During pregnancy the uterine spiral arteries undergo major vascular remodelling to ensure sufficient uteroplacental perfusion to support the fetus. In pregnancies complicated by hypertensive disorders this remodelling is deficient leading to impaired uteroplacental blood flow and poor maternal and fetal outcomes. Evidence suggests that the uterine arteries can be ‘primed’ by changes in gene expression and maternal factors to ensure appropriate remodelling takes place. This study aimed to examine the early-pregnancy associated gene expression changes in the uterine arteries (UAs) of stroke-prone spontaneously hypertensive rats (SHRSP) compared to their normotensive counterparts, Wistar-Kyoto rats (WKY). Design and method: SHRSP and WKY females were time-mated with males of the relevant strain. On gestational day (GD)6.5 dams were sacrificed, the UA collected and processed for RNA-sequencing alongside age-matched virgin controls (n = 3/group). Structure & function were assessed by wire and pressure myography. Gene expression changes were investigated using Ingenuity Pathway Analysis (IPA®) with padj > 0.05. Results: No structural or functional differences were observed in UAs between strains (SHRSP, WKY) or pregnancy (NP, P) using myography. SHRSP UAs showed a greater number of differentially expressed genes (DEGs) across pregnancy than WKY. WKY UAs exhibited an expression pattern of reduced Ca2+ handling and RAAS components with an increase in ATP production between NP and P states. SHRSP P UAs showed an increased expression of DEGs related to immune response, ROS production and downstream effectors of the RAAS in comparison to SHRSP NP UAs. These changes were not shared between strains. Conclusions: These results suggest SHRSP UAs experience gene expression changes in inflammation and oxidative stress pathways in early pregnancy that may induce failed priming of the UA. This may subsequently contribute to adverse vascular remodelling and placental ischaemia in later gestation characteristic of hypertensive pregnancies.

Distinct uterine artery gene expression profiles during early gestation in the stroke-prone spontaneously hypertensive rat.

During pregnancy, the uterine spiral arteries undergo major vascular remodeling to ensure sufficient uteroplacental perfusion to support the fetus. In pregnancies complicated by hypertensive disorders, this remodeling is deficient leading to impaired uteroplacental blood flow and poor maternal and fetal outcomes. The underlying genetic mechanisms for failed vascular remodeling are not fully understood. This study aimed to examine the early-pregnancy-associated gene changes in the uterine arteries of spontaneously hypertensive stroke-prone rats (SHRSP) compared with their normotensive counterparts, Wistar-Kyoto rats (WKY). Uterine arteries from gestational day 6.5 WKY and SHRSP were processed for RNA-sequencing, along with virgin, age-matched controls for each strain. Gene expression changes were identified and biological pathways were implicated and interpretated using ingenuity pathway analysis (IPA). This study found that WKY uterine arteries from early pregnancy exhibit a gene expression pattern that is suggestive of a pregnancy-dependent reduction in Ca2+ handling and renin-angiotensin-aldosterone system (RAAS) components and an increase in ATP production. In contrast, the expression pattern of pregnant SHRSP uterine arteries was dominated by an elevated immune response and increased production of reactive oxygen species (ROS) and downstream effectors of the RAAS. These results suggest that in a rat model, hypertension during pregnancy impacts uterine artery gene expression patterns as early as the first week of pregnancy. The pathway changes involved may underlie or contribute to the adverse vascular remodeling and resultant placental ischemia and systemic vascular dysfunction observed in SHRSP in late gestation.

Assessing Cardiovascular Risk by Using the Fat Attenuation Index in Coronary CT Angiography.

Coronary CT angiography (CCTA) has evolved into a first-line diagnostic test for the investigation of chest pain. Despite advances toward standardizing the reporting of CCTA through the Coronary Artery Disease Reporting and Data System (or CAD-RADS) tool, the prognostic value of CCTA in the earliest stages of atherosclerosis remains limited. Translational work on the bidirectional interplay between the coronary arteries and the perivascular adipose tissue (PVAT) has highlighted PVAT as an in vivo molecular sensor of coronary inflammation. Coronary inflammation is dynamically associated with phenotypic changes in its adjacent PVAT, which can now be detected as perivascular attenuation gradients at CCTA. These gradients are captured and quantified through the fat attenuation index (FAI), a CCTA-based biomarker of coronary inflammation. FAI carries significant prognostic value in both primary and secondary prevention (patients with and without established coronary artery disease) and offers a significant improvement in cardiac risk discrimination beyond traditional risk factors, such as coronary calcium, high-risk plaque features, or the extent of coronary atherosclerosis. Thanks to its dynamic nature, FAI may be used as a marker of disease activity, with observational studies further suggesting that it tracks the response to anti-inflammatory interventions. Finally, radiotranscriptomic studies have revealed complementary radiomic patterns of PVAT, which detect more permanent adverse fibrotic and vascular PVAT remodeling, further expanding the value of PVAT phenotyping as an important readout in modern CCTA analysis. © RSNA, 2021.

Abstract 15326: Inactivation of Mitochondrial Deacetylase Sirt3 Induces Oxidative Stress, Promotes Vascular Hypertrophy, Increases Aortic Dissections, Exacerbates Hypertension and Mortality

Introduction: Vascular dysfunction plays a key role in hypertension and cardiovascular disease, which causes one-third of deaths worldwide. Mitochondrial dysfunction contributes to these conditions; however, specific mechanisms are not clear. We showed inactivation of mitochondrial deacetylase Sirt3 in arterioles from patients with essential hypertension associated with superoxide dismutase inactivation, vascular inflammation and oxidative stress. Hypothesis: We hypothesized that the loss of vascular Sirt3 induces oxidative stress, promotes vascular dysfunction and hypertension. Methods: To test this hypothesis, we developed tamoxifen-inducible smooth muscle specific Sirt3 knockout mice (SmcSirt3KO) by crossing the Sirt3flox/flox mice with mice carrying a gene for inducible Cre in the vascular smooth muscle cells. Results and Discussion: Hypertension was modestly increased but considerably increased mortality in angiotensin II-infused SmcSirt3KO mice (35% vs 5% in WT) which was associated with higher rate of aortic dissections (50% vs 10% in WT). The basal superoxide and nitric oxide levels were not affected in SmcSirt3KO mice, however, angiotensin II infusion significantly increased superoxide and nitric oxide inactivation in SmcSirt3KO mice compared with wild-type mice supporting the pathological role of smooth muscle Sirt3 impairment. Post-mortem analysis showed high frequency of abdominal aortic aneurysms in angiotensin II-infused SmcSirt3KO mice suggesting that adverse vascular remodeling contributed to high mortality in these mice. To gain further insight into vascular pathology we performed histological examination using Verhoeff-van Gieson staining. Angiotensin II-infused SmcSirt3KO mice had 5-time higher abdominal aortic dissections rate, increased vascular hypertrophy, and disrupted elastic lamellae. Conclusion: Aortic dissection is a catastrophic disease with high mortality and morbidity characterized by fragmentation of elastin and smooth muscle cell dysfunction. Our data suggest that Sirt3 impairment can contribute to vascular hypertrophy, aortic dissection, end-organ-damage and mortality. It is conceivable that targeting Sirt3 may have therapeutic potential in cardiovascular disease.

Up-regulation of FoxO1 contributes to adverse vascular remodelling in type 1 diabetic rats.

Vascular complications from diabetes often result in poor outcomes for patients, even after optimized interventions. Forkhead box protein O1 (FoxO1) is a key regulator of cellular metabolism and plays an important role in vessel formation and maturation. Alterations of FoxO1 occur in the cardiovascular system in diabetes, yet the role of FoxO1 in diabetic vascular complications is poorly understood. In Streptozotocin (STZ)‐induced type 1 diabetic rats, FoxO1 expression was up‐regulated in carotid arteries at 8 weeks of diabetes that was accompanied with adverse vascular remodelling characterized as increased wall thickness, carotid medial cross‐sectional area, media‐to‐lumen ratio and decreased carotid artery lumen area. This adverse vascular remodelling induced by hyperglycaemia in diabetic rats required FoxO1 activation as pharmacological inhibition of FoxO1 with 50mg/kg AS1842856 (AS) reversed vascular remodelling in type 1 diabetic rats. The adverse vascular remodelling in type 1 diabetes mellitus (T1DM) occurred concomitantly with increases in pro‐inflammatory factors, adhesion factors, apoptosis, NOD‐like receptor family protein‐3 inflammasome activation and the phenotypic switch of arterial smooth muscle cells, which were all reversed by AS. In addition, FoxO1 inhibition counteracted the down‐regulation of its upstream mediator PDK1 in T1DM. PDK1 activator reduced FoxO1 nuclear translocation, which serves as the basis for subsequent transcriptional regulation during hyperglycaemia. Taken together, our data suggest that FoxO1 is a critical trigger for type 1 diabetes‐induced vascular remodelling in rats, and inhibition of FoxO1 thus offers a potential therapeutic option for diabetes‐associated cardiovascular diseases.

Beta 1 adrenoceptor blockade promotes angiogenesis in hypertrophied myocardium of transverse aortic constricted mice.

Left ventricular hypertrophy (LVH) is an adaptive structural remodelling consequent to uncontrolled blood pressure. Impaired angiogenesis plays a vital role in transiting LVH into cardiac failure. Catecholamines modulate myocardial function through beta adrenoceptors, and their blockers (β-AR) reduce cardiovascular morbidity and mortality by decelerating the LVH progression. Nonetheless, the effect of β-AR blockers on myocardial vascular bed remains largely obscure. Hence, this study is focussed on analysing the possible outcomes of β-AR blockers on myocardial vascular remodelling using a surgically induced LVH mice model. Transverse aortic constricted mice and sham-operated mice were administered with metoprolol at a dose of 30mg/kg/d for 60days and myocardial vascular endothelial growth factor (VEGF) alpha levels, GSH/GSSG ratio, myocardial protein carbonyl content, hypertrophy index and global myocardial function, trans-aortic fluid dynamics and expression pattern of angiopoietin-1 and VEGF alpha were assessed. These findings were further confirmed by histochemical analysis for myocardial capillary density, perivascular fibrosis ratio and intimal thickening. Sub- chronic β-AR blockade reduced the oxidative stress, hypertrophic index, intimal thickening and perivascular fibrosis ratio. A marked increase in myocardial VEGF, angiopoietin 1, global myocardial function and myocardial capillary density was also observed. There was a reduction in the LVH and upregulation of myocardial angiogenesis concluding that β-AR blockers prevent adverse vascular remodelling which might underlie its concealed mechanism of action.

Glycolaldehyde-modified proteins cause adverse functional and structural aortic remodeling leading to cardiac pressure overload

Growing evidence supports the role of advanced glycation end products (AGEs) in the development of diabetic vascular complications and cardiovascular diseases (CVDs). We have shown that high-molecular-weight AGEs (HMW-AGEs), present in our Western diet, impair cardiac function. Whether HMW-AGEs affect vascular function remains unknown. In this study, we aimed to investigate the impact of chronic HMW-AGEs exposure on vascular function and structure. Adult male Sprague Dawley rats were daily injected with HMW-AGEs or control solution for 6 weeks. HMW-AGEs animals showed intracardiac pressure overload, characterized by increased systolic and mean pressures. The contraction response to PE was increased in aortic rings from the HMW-AGEs group. Relaxation in response to ACh, but not SNP, was impaired by HMW-AGEs. This was associated with reduced plasma cyclic GMP levels. SOD restored ACh-induced relaxation of HMW-AGEs animals to control levels, accompanied by a reduced half-maximal effective dose (EC50). Finally, collagen deposition and intima-media thickness of the aortic vessel wall were increased with HMW-AGEs. Our data demonstrate that chronic HMW-AGEs exposure causes adverse vascular remodelling. This is characterised by disturbed vasomotor function due to increased oxidative stress and structural changes in the aorta, suggesting an important contribution of HMW-AGEs in the development of CVDs.

BET bromodomain-containing epigenetic reader proteins regulate vascular smooth muscle cell proliferation and neointima formation.

Recent studies revealed that the bromodomain and extra-terminal (BET) epigenetic reader proteins resemble key regulators in the underlying pathophysiology of cancer, diabetes, or cardiovascular disease. However, whether they also regulate vascular remodelling processes by direct effects on vascular cells is unknown. In this study, we investigated the effects of the BET proteins on human smooth muscle cell (SMC) function in vitro and neointima formation in response to vascular injury in vivo. Selective inhibition of BETs by the small molecule (+)-JQ1 dose-dependently reduced proliferation and migration of SMCs without apoptotic or toxic effects. Flow cytometric analysis revealed a cell cycle arrest in the G0/G1 phase in the presence of (+)-JQ1. Microarray- and pathway analyses revealed a substantial transcriptional regulation of gene sets controlled by the Forkhead box O (FOXO1)1-transcription factor. Silencing of the most significantly regulated FOXO1-dependent gene, CDKN1A, abolished the antiproliferative effects. Immunohistochemical colocalization, co-immunoprecipitation, and promoter-binding ELISA assay data confirmed that the BET protein BRD4 directly binds to FOXO1 and regulates FOXO1 transactivational capacity. In vivo, local application of (+)-JQ1 significantly attenuated SMC proliferation and neointimal lesion formation following wire-induced injury of the femoral artery in C57BL/6 mice. Inhibition of the BET-containing protein BRD4 after vascular injury by (+)-JQ1 restores FOXO1 transactivational activity, subsequent CDKN1A expression, cell cycle arrest and thus prevents SMC proliferation in vitro and neointima formation in vivo. Inhibition of BET epigenetic reader proteins might thus represent a promising therapeutic strategy to prevent adverse vascular remodelling.