Adverse Vascular Remodeling Research Articles

Abstract 4138731: Clonal Hematopoiesis of Indeterminant Potential is Associated with Pulmonary Arterial Hypertension

Background: Pulmonary Arterial Hypertension (PAH) is a fatal cardiopulmonary disorder characterized by adverse vascular remodelling of small pulmonary arteries, which increases resistance and demand on the right ventricle (RV), ultimately leading to RV fibrosis and failure. Emerging evidence suggests that inflammation plays a crucial role in PAH pathogenesis. Here, we study Clonal Hematopoiesis of Indeterminate Potential (CHIP), a disorder characterized by somatic mutations in genes such as DNMT3A and TET2 , that promotes an inflammatory phenotype, in the development of PAH. Methods: We performed deep, targeted panel sequencing on 1659 PAH patients from the PAH Biobank and 3644 controls (3401 Vanderbilt University Biorepository patients and 243 participants recruited by the Queen’s Genomics Centre at Ongwanada). Variants in known CHIP genes expressed at a variant allele frequency (VAF) > 2% were classified as CHIP. Genes with a VAF > 25% and <50% were considered CHIP if located in reported CHIP hotspot regions. The prevalence of CHIP mutations was compared between controls and PAH patients. Logistic regression was used for statistical analysis. Results: We identified 242 CHIP variants in the 1659 PAH patients. DNMT3A was the most mutated gene (116/242 = 48%), followed by TET2 (46/242=19%). After adjusting for age and sex, we identified a significant association between all CHIP variants combined and PAH (OR: 23.35 [7.67, 71.03]; p<0.0001). Further, DNMT3A CHIP (OR: 25.44 [5.37, 120.40]; p<0.0001), non- DNMT3A CHIP (OR: 26.80 [5.56, 129.23]; p<0.0001) and TET2 CHIP (OR: 13.69 [1.29, 145.30]; p=0.03) were all associated with PAH. A higher proportion of PAH patients under the age of 70 were found to have CHIP variants compared to controls and this was significant for individuals between 60-69 years of age (p=0.037). While there was a 3.8:1 female-to-male ratio of PAH patients, there was a 5.8:1 female-to-male preponderance of DNMT3A variants (p=0.039) (4.3:1 for all CHIP; p=ns), suggesting DNMT3A variants are more common in female patients. The presence of CHIP variants had no significant effect on PAH patient 10-year survival. Conclusion: This research reveals a significant association between CHIP variants, specifically in DNMT3A and TET2, and PAH. The prevalence of CHIP is higher in PAH patients aged 40 to 70 compared to controls and is more common in female patients. These findings suggest that CHIP is a significant risk factor for the development of PAH.

Long-acting CRF2 receptor agonist COR-1389 improves cardiopulmonary function parameters in monocrotaline-induced pulmonary hypertension and right heart failure rat model

Abstract Background Pulmonary hypertension (PH) associated with right heart failure (RHF) poses a significant therapeutic challenge. Short term studies have shown that urocortin-2 (UCN-2) administration, either intravenously or subcutaneously, can ameliorate cardiac and/or pulmonary parameters in human heart failure (HF) and in animal models of PH and RHF. Purpose This study aimed to evaluate the potential benefits of COR-1389, a long-acting CRF2 receptor agonist, on cardiopulmonary function and adverse remodeling in a rat model of monocrotaline (MCT)-induced PH and RHF. Method Monocrotaline (40 mg/kg) was administered subcutaneously in rats on Day-0 to induce PH and RHF, while the control group received vehicle. After 14 days, MCT-injected rats were evenly allocated into two groups based on echocardiography parameters of accelerated time/ejection time ratio and tricuspid annular plane systolic excursion (TAPSE), before receiving either COR-1389 (100 ug/kg) or its vehicle subcutaneously every 4 days for 14 days. On Day-28, echocardiography was repeated in all groups, followed by right heart catheterization to directly measure pulmonary hemodynamics. Heart and lung samples were prepared for histological analysis. Results By Day-28, MCT-treated rats exhibited significantly elevated mean pulmonary arterial pressure (mPAP) and right ventricular (RV) mass (Fulton Index/BW), along with decreased RV function (increased TAPSE) and reduced cardiac output (CO) compared to control rats. These changes were accompanied by severe tissue remodeling, including increased vascular muscularization (alpha-smooth muscle actin content) and pulmonary arterial wall thickening, RV fibrosis, and cardiomyocyte hypertrophy. Following 14 days of curative treatment, MCT+COR-1389 compared to MCT, significantly decreased mPAP and RV mass (Fulton Index/BW), while RV function improved (reduced TAPSE) and CO was increased. Moreover, COR-1389 attenuated adverse pulmonary vascular remodeling (reduced muscularization and arterial wall thickening), RV fibrosis, and cardiomyocyte hypertrophy, consistent with its hemodynamic effects. Conclusions Chronic CRF2 agonism with COR-1389 improved dysregulated cardiac and pulmonary function and structure in the MCT rat model, suggesting its potential for the treatment of PH and RHF.

Protease activated receptor 2 deficiency retards progression of abdominal aortic aneurysms by modulating phenotypic transformation of vascular smooth muscle cells via ERK signaling

Abdominal aortic aneurysm (AAA) is characterized by localized structural deterioration of the aortic wall, leading to progressive dilatation and rupture. Protease activated receptor 2 (PAR2) dependent signaling has been implicated in the pathophysiology of atherosclerosis through the regulation of smooth muscle cell function. However, its role in AAA remains unclear. This study investigates the function and potential mechanism of PAR2 in AAA progression. Angiotensin II (Ang II) and β-aminopropionitrile (BAPN) were administered to wild type (WT) mice to induce AAA. Increased PAR2 expression was observed in the aneurysmal tissues of these mice and in Ang II-treated vascular smooth muscle cells (VSMCs). We demonstrated that PAR2 deficiency markedly inhibited aorta dilatation and vascular remodeling in the AAA model relative to WT mice. Immunohistochemical staining showed significant upregulation of contractile markers and a reduction in synthetic markers in PAR2 knockout mice. Consistent with in vivo results, PAR2 knockdown diminished the effects of Ang II on VSMCs phenotypic switching, resulting in reduced proliferation and migration. Conversely, a PAR2 agonist (SLIGRL) induced the opposite effect, which was partially mitigated by pretreatment with an extracellular signal-regulated kinase (ERK) inhibitor (PD98059). This study suggests that PAR2 deficiency restrains aortic expansion and mitigates adverse vascular remodeling in AAA models, mediated in part by the ERK signaling pathway, indicating that PAR2 could be a potential therapeutic target for mitigating AAA development or progression.

Identification of SNHG11 as a Therapeutic Target in Pulmonary Hypertension.

Pulmonary hypertension (PH) is a life-threatening condition characterized by pulmonary vascular remodeling and endothelial dysfunction. Current therapies primarily target vasoactive imbalances but often fail to address adverse vascular remodeling. Long non-coding RNA (lncRNA), which are key regulators of various cellular processes, remain underexplored in the context of PH. To investigate the role of lncRNA in PH, we performed a comprehensive analysis using Weighted Gene Co-expression Network Analysis (WGCNA) on the GSE113439 dataset, comprising human lung tissue samples from different PH subtypes. Our analysis identified the lncRNA SNHG11 as consistently downregulated in PH. Functional assays in human pulmonary artery endothelial cells (HPAECs) demonstrated that SNHG11 plays a critical role in modulating inflammation, cell proliferation, apoptosis, and the JAK/STAT and MAPK signaling pathways. Mechanistically, SNHG11 influences the stability of PRPF8, a crucial mRNA spliceosome component, thereby affecting multiple cellular functions beyond splicing. In vivo experiments using a hypoxic rat model showed that knockdown of SNHG11 alleviates PH development and improves right ventricular function. These findings highlight SNHG11 as a key regulator in PH pathogenesis and suggest it as a potential therapeutic target.

New and Emerging Therapeutic Drugs for the Treatment of Pulmonary Arterial Hypertension: A Systematic Review.

Pulmonary arterial hypertension (PAH) is a serious, progressive, and potentially fatal lung disease characterized by a gradual increase in mean pulmonary arterial pressure to over 20 mmHg at rest. The pathogenesis of PAH is multifactorial. It involves dynamic obstruction of the pulmonary vasculature through vasoconstriction, structural obstruction due to adverse vascular remodeling, and pathological obstruction caused by vascular fibrosis and stiffening, which reduces compliance. PAH often presents with vague initial symptoms and is frequently diagnosed at an advanced stage. The increased pulmonary arterial pressure leads to vascular remodeling, eventually resulting in right ventricular hypertrophy and failure. PAH is a rare condition with a median life expectancy of three years, underscoring the need for effective treatment alternatives. Several FDA-approved therapeutic options are available, including prostacyclin analogs (epoprostenol, iloprost, and treprostinil), the non-prostanoid IP receptor agonist selexipag, selective endothelin receptor antagonists (ERA) (ambrisentan, bosentan, and macitentan), phosphodiesterase 5 inhibitors (sildenafil and tadalafil), and the soluble guanylate cyclase (sGC) stimulator riociguat. Despite these advancements, current medications do not provide a permanent cure. This study presents an overview of current and emerging PAH therapies through a systematic literature review. It involved an analysis of nine studies and a review of 800 papers from reputable journals published between 2013 and June 2023. The research focused on drug effects on the six-minute walk distance (6-MWD) and associated side effects in randomized controlled trials. The review found that while udenafil, imatinib, racecadotril, sotatercept, anastrozole, riociguat, tacrolimus, and ralinepag were evaluated, imatinib was notably associated with adverse side effects. Conversely, udenafil, racecadotril, sotatercept, anastrozole, riociguat, tacrolimus, and ralinepag were found to be safe, well-tolerated, and effective in improving hemodynamic measures and 6-MWDs. This study aims to summarize the developing treatment options currently under clinical trials, highlighting the need for further trials before their application in clinical practice.

Prostanoids in Cardiac and Vascular Remodeling.

Prostanoids are biologically active lipids generated from arachidonic acid by the action of the COX (cyclooxygenase) isozymes. NSAIDs, which reduce the biosynthesis of prostanoids by inhibiting COX activity, are effective anti-inflammatory, antipyretic, and analgesic drugs. However, their use is limited by cardiovascular adverse effects, including myocardial infarction, stroke, hypertension, and heart failure. While it is well established that NSAIDs increase the risk of atherothrombotic events and hypertension by suppressing vasoprotective prostanoids, less is known about the link between NSAIDs and heart failure risk. Current evidence indicates that NSAIDs may increase the risk for heart failure by promoting adverse myocardial and vascular remodeling. Indeed, prostanoids play an important role in modulating structural and functional changes occurring in the myocardium and in the vasculature in response to physiological and pathological stimuli. This review will summarize current knowledge of the role of the different prostanoids in myocardial and vascular remodeling and explore how maladaptive remodeling can be counteracted by targeting specific prostanoids.

Pulmonary hypertension.

Pulmonary hypertension encompasses a range of conditions directly or indirectly leading to elevated pressures within the pulmonary arteries. Five main groups of pulmonary hypertension are recognized, all defined by a mean pulmonary artery pressure of >20 mmHg: pulmonary arterial hypertension (rare), pulmonary hypertension associated with left-sided heart disease (very common), pulmonary hypertension associated with lung disease (common), pulmonary hypertension associated with pulmonary artery obstructions, usually related to thromboembolic disease (rare), and pulmonary hypertension with unclear and/or multifactorial mechanisms (rare). At least 1% of the world's population is affected, with a greater burden more likely in low-income and middle-income countries. Across all its forms, pulmonary hypertension is associated with adverse vascular remodelling with obstruction, stiffening and vasoconstriction of the pulmonary vasculature. Without proactive management this leads to hypertrophy and ultimately failure of the right ventricle, the main cause of death. In older individuals, dyspnoea is the most common symptom. Stepwise investigation precedes definitive diagnosis with right heart catheterization. Medical and surgical treatments are approved for pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension. There are emerging treatments for other forms of pulmonary hypertension; but current therapy primarily targets the underlying cause. There are still major gaps in basic, clinical and translational knowledge; thus, further research, with a focus on vulnerable populations, is needed to better characterize, detect and effectively treat all forms of pulmonary hypertension.

Flow-induced high frequency vascular wall vibrations in an arteriovenous fistula: a specific stimulus for stenosis development?

Hemodialysis is the lifeline for nearly three million end stage renal disease patients worldwide. Native arteriovenous fistula (AVF) is the preferred vascular access, but 40% fail within 1 year. We recently demonstrated that AVFs harbour transitional flows and the goal of the present study was to investigate whether the associated high-frequency pressure fluctuations could promote vibrations within the vascular wall. We acquired MRI images and flow rates immediately after surgery in one patient and generated a 3D patient-specific model. High-fidelity fluid structure interaction simulations revealed the presence of wall vibrations in distinct frequency bands up to 200 Hz and amplitude of 200 μm. A sensitivity analysis to assess the impact of flow rates, and vascular wall stiffness and thickness, changes that typically occur during AVF maturation, confirmed the robustness of the results. Interestingly, the vibrations were always predominant at the anastomosis floor and on the inner venous side, which correlates with typical stenotic regions. As studies seeking to correlate aberrant stresses and vascular remodelling have been largely inconclusive, the focal colocalization between vibrations and stenosis may suggest an unknown mechanobiological process between high-frequency mechanical stresses within the vascular wall and adverse vascular remodelling.

Role of Bisoprolol in Heart Failure Management: A Consensus Statement from India.

In India, heart failure (HF) is an important health concern affecting younger age groups than the western population. A limited number of Indian patients receive guideline-directed medical therapy (GDMT). Selective β-1 blockers (BB) are one of the GDMTs in HF and play an important role by decreasing the sympathetic overdrive. The BB reduces heart rate (HR) reverse the adverse cardiac (both ventricular and atrial), vascular, and renovascular remodeling seen in HF. Bisoprolol, a β-1 blocker, has several advantages and can be used across a wide spectrum of HF presentations and in patients with HF and comorbid conditions such as coronary artery disease (CAD), atrial fibrillation (AF), post-myocardial infarction (MI), uncontrolled diabetes, uncontrolled hypertension, and renal impairment. Despite its advantages, bisoprolol is not optimally utilized for managing HF in India. This consensus builds on updated evidence on the efficacy and safety of bisoprolol in HF and recommends its place in therapy with a focus on Indian patients with HF.

Abstract 13229: Coiled-Coil Domain-Containing Protein 80 Protects Against Aortic Dissection by Maintaining the Contractile Smooth Muscle Cell Phenotype

Background: Aortic dissection (AD) is a life-threatening medical emergency characterized by adverse vascular remodeling. Effective prevention and treatment options are lacking for AD. Coiled-coil domain-containing protein 80 (CCDC80) plays an essential role in regulating vascular remodeling. In the present study, we aimed to define the role of CCDC80 in the formation and development of AD. Methods: The expression and subcellular localization of CCDC80 were determined in human and mouse AD. CCDC80 knockout mice (CCDC80 –/– ) and vascular smooth muscle cell (VSMC)-specific CCDC80 knockout mice (CCDC80 fl/fl SM22α Cre + ) were treated with angiotensin II (Ang II) or Ang II combined with β-aminopropionitrile monofumarate (BAPN) to induce AD models. RNA-Seq analysis combined with immunoprecipitation and blockage of the JAK2/STAT3 signaling pathway in CCDC80 –/– mice were used to evaluate the effect of CCDC80 deficiency on this pathway. Results: CCDC80 was downregulated in VSMCs in human and mouse AD. CCDC80 – / – mice challenged with Ang II and BAPN developed AD with higher frequency and severity compared with their littermate controls (66.7% vs. 100%, p < 0.05). Remarkably, compared with littermate controls treated with Ang II, CCDC80 –/– mice (8.3% vs. 87.5%, p < 0.05) and CCDC80 fl/fl SM22α Cre + mice (12.5% vs. 80%, p < 0.05) frequently developed AD with severe elastin fragmentation and collagen deposition. CCDC80 interacted with JAK2; CCDC80 deficiency could promote VSMC phenotype switching, proliferation, and migration as well as matrix metalloproteinase production by activating the JAK2/STAT3 signaling pathway. The JAK2/STAT3 pathway-specific inhibitor ameliorated adverse vascular remodeling and reduced AD formation (90% vs. 55%, p < 0.05) in CCDC80 knockout mice. Conclusion: CCDC80 deficiency exacerbates the progression of AD by activating the JAK2/STAT3 pathway involved in regulating the phenotype switching and function of VSMCs. Our findings suggest that CCDC80 is a potential target for the prevention and treatment of AD.

Abstract 17430: Targeting DNA Hypermethylation With Hypomethylating Drugs: Implications for Pulmonary Arterial Hypertension

Introduction: Pulmonary arterial hypertension (PAH) is a lethal vasculopathy characterized by sustained vasoconstriction and remodeling of pulmonary arteries. Excessive proliferation and reduced apoptosis of pulmonary artery smooth muscle cells (PASMCs) contribute to pulmonary artery remodeling, with limited efficacy of current pharmacotherapies. Increased DNA methylation (DNAm) has been implicated in pro-proliferative phenotypes and disease progression in cancer and cardiovascular diseases. Hypothesis: We hypothesized that increased DNAm contributes to the pro-survival phenotype of PAH-PASMCs and that targeting DNA methylation could improve PAH development. Methods and Results: Our study revealed a global increase of DNAm in remodeled pulmonary arteries of human PAH patients and three preclinical models (namely monocrotaline, sugen hypoxia, Fawn hooded rats, p<0.05, immunofluorescence [IF] 5mc/SMA). In vitro, PAH-PASMCs exhibited elevated DNAm levels (IF 5mc, p<0.05), increased expression of DNA methyltransferases (DNMT1, DNMT3a; Western blot [WB], p<0.05), and decreased expression of DNA demethylase (TET2; WB, p<0.05). Consequently, hypomethylating drug Zebularine demonstrated dose-dependent reductions in PAH-PASMC proliferation (WB for surviving, plk1, MCM2; IF ki67, p<0.05) and increased apoptosis (WB for Bax/BCL2; IF annexinV, p<0.05,). Transcriptomic and gene ontology analyses indicated that these effects likely involve the downregulation of biological processes related to the cell cycle and mitosis. In vivo treatment with Zebularine (10 mg/kg, 2 weeks, intraperitoneal injection) improved PAH hemodynamics (e.g., decreased RVSP, vascular resistances, p<0.05), decreased PASMC methylation (IF 5mc/SMA, p<0.05) and proliferation (IF ki67/SMA, p<0.05), and mitigated adverse pulmonary vascular remodeling in two rodent models of the disease (monocrotaline and sugen hypoxia). Statistics: unpaired t test (2 groups), ANOVA (> 2 groups). Conclusions: Our findings demonstrate an association between increased DNA methylation and PAH development. Targeting DNAm represents a potential therapeutic avenue for PAH, as evidenced by the beneficial effects of Zebularine in improving PAH-related phenotypes.

Abstract 15534: Identification of Narciclasine, a Potential Drug to Treat PAH by Unbiased Pharmaco-Transcriptomic Study

Introduction: Pulmonary arterial hypertension (PAH) is a life-threatening vascular disorder characterized by persistent vasoconstriction and detrimental remodeling of the pulmonary blood vessels. This incurable disease is marked by a complex gene expression reprogramming that triggers, among other, metabolic disorders, heightened by inflammation, and the development of a pro-survival phenotype in pulmonary arterial smooth muscle cells (PASMC).We conducted an unbiased transcriptomic study using lung samples from 16 PAH patients and 12 non-PAH controls and identified 4013 differentially expressed genes. Leveraging in silico pharmaco-transcriptomic analysis (utilizing the Lincs and Sigcom databases), we identified narciclasine as a potential drug. Hypothesis: Consequently, we hypothesized that narciclasine could offer improvements in PAH. Methods and Results: In vivo , we administered narciclasine treatment (1 mg/kg, 2 weeks, gavage) in a murine model of PH (monocrotaline model, 60 mg/kg, sc.) and observed improved PH hemodynamics (RVSP, PAAT, TPR), reduced inflammation (CD68 immunofluorescence (IF)), decreased PASMC survival (PCNA and cleaved caspase 3 IF), and alleviated adverse vascular remodeling (Elastic van Gieson Stain Kit). In vitro , narciclasine exhibited a dose-dependent reduction of cell proliferation (IF: ki67; Western blot Survivin, PCNA and PLK1) and increased apoptosis PAH-PASMC (IF: cleaved caspase 3; Wb: Bax and Bcl2). Transcriptomic study (conducted in treated PASMCs) reveals that the therapeutic effects of narciclasine in PAH may be attributed to decreased glycosylation (Gene Ontology analysis). We further observed increased glycosylation in remodeled arteries from PAH lungs, PH preclinical models, and cultured PASMC (Periodic Acid Schiff Kit). Subsequently, we validated that narciclasine reduced glycosylation and downregulated the expression of glycosylation enzymes (by wb: GFAT, NGT, OGT) both in vitro and in vivo. Statistical tests used: unpaired t (2 groups), ANOVA (> 2 groups). Conclusions: In conclusion, our unbiased pharmaco-transcriptomic study identifies narciclasine as a potential therapeutic drug for PAH. Notably, its efficacy appears to be mediated by the reduction of glycosylation.

Abstract P3045: MicroRNA-31-5p Is Upregulated During Neointima Formation And Promotes Smooth Muscle Cell Proliferation And Migration By Regulating Krüppel-like Factor 4 (KLF4)

In the context of CVDs, microRNAs (miRs) have emerged as potential therapeutic targets for preventing adverse vascular remodeling and restenosis, given their ability to modulate multiple signaling pathways and cellular processes. Here, we propose that targeting miR-31-5p might be an effective approach to enhance vascular healing and regeneration in a cell-specific manner, thereby limiting angioplasty-related complications. A screening of murine neointimal tissue for differentially regulated miRs revealed robustly increased expression levels of miR-31-5p over time. Subsequently, expression levels of miR-31-5p were confirmed by qRT-PCR in human coronary artery endothelial cells (EC) and -smooth muscle cells (SMC). Further, the effect of miR-31-5p on cellular function was investigated and possible targets were identified and confirmed on mRNA and protein level. Expression analysis revealed a significant upregulation of miR-31-5p (p<0.0001) in C57BL/6J mice following wire-induced injury of the femoral artery at 7 and 21 days. In vitro, miR-31-5p was significantly upregulated in SMC (p<0,05 ) following serum stimulation, whereas only a slightly enhanced expression was observed in EC. On a functional level, miR-31-5p revealed dissenting effects on EC and SMC: Migration and proliferation were not altered in EC (p>0.05). In contrast, knockdown of miR-31-5p significantly reduced the migration (p<0,05) and proliferation in SMC (p<0,01) without detectable apoptotic effects. Systematic in silico target screens suggested KLF4 as potential target. Knock down of miR-31-5p resulted in a significant upregulation of KLF4 in SMC (p<0,01), whereas overexpression resulted in a significant downregulation of KLF4 in SMC (p<0,05) on mRNA- and protein level. Here, we report that miR-31-5p is robustly upregulated during neointima formation and seems to exert a functional role in SMC rather than EC since knockdown of miR-31-5p was able to prevent SMC proliferation and migration. Mechanistically, KLF4 identified as a direct target of miR-31-5p can mediate the observed effects. Thus, miR-31-5p might represent an attractive target to selectively modulate SMC dysfunction following vascular intervention, limiting neointima formation in treated vessels.

Coronary microevaginations characterize culprit plaques and their inflammatory microenvironment in a subtype of acute coronary syndrome with intact fibrous cap: results from the prospective translational OPTICO-ACS study.

Coronary microevaginations (CMEs) represent an outward bulge of coronary plaques and have been introduced as a sign of adverse vascular remodelling following coronary device implantation. However, their role in atherosclerosis and plaque destabilization in the absence of coronary intervention is unknown. This study aimed to investigate CME as a novel feature of plaque vulnerability and to characterize its associated inflammatory cell-vessel-wall interactions. A total of 557 patients from the translational OPTICO-ACS study programme underwent optical coherence tomography imaging of the culprit vessel and simultaneous immunophenotyping of the culprit lesion (CL). Two hundred and fifty-eight CLs had a ruptured fibrous cap (RFC) and one hundred had intact fibrous cap (IFC) acute coronary syndrome (ACS) as an underlying pathophysiology. CMEs were significantly more frequent in CL when compared with non-CL (25 vs. 4%, P < 0.001) and were more frequently observed in lesions with IFC-ACS when compared with RFC-ACS (55.0 vs. 12.7%, P < 0.001). CMEs were particularly prevalent in IFC-ACS-causing CLs independent of a coronary bifurcation (IFC-ICB) when compared with IFC-ACS with an association to a coronary bifurcation (IFC-ACB, 65.4 vs. 43.7%, P = 0.030). CME emerged as the strongest independent predictor of IFC-ICB (relative risk 3.36, 95% confidence interval 1.67-6.76, P = 0.001) by multivariable regression analysis. IFC-ICB demonstrated an enrichment of monocytes in both culprit blood analysis (culprit ratio: 1.1 ± 0.2 vs. 0.9 ± 0.2, P = 0.048) and aspirated culprit thrombi (326 ± 162 vs. 96 ± 87 cells/mm2, P = 0.017), while IFC-ACB confirmed the accumulation of CD4+ T cells, as recently described. This study provides novel evidence for a pathophysiological involvement of CME in the development of IFC-ACS and provides first evidence for a distinct pathophysiological pathway for IFC-ICB, driven by CME-derived flow disturbances and inflammatory activation involving the innate immune system. Registration of the study at clinicalTrials.gov (NCT03129503).

Inflammation and immunity in the pathogenesis of hypoxic pulmonary hypertension.

Hypoxic pulmonary hypertension (HPH) is a complicated vascular disorder characterized by diverse mechanisms that lead to elevated blood pressure in pulmonary circulation. Recent evidence indicates that HPH is not simply a pathological syndrome but is instead a complex lesion of cellular metabolism, inflammation, and proliferation driven by the reprogramming of gene expression patterns. One of the key mechanisms underlying HPH is hypoxia, which drives immune/inflammation to mediate complex vascular homeostasis that collaboratively controls vascular remodeling in the lungs. This is caused by the prolonged infiltration of immune cells and an increase in several pro-inflammatory factors, which ultimately leads to immune dysregulation. Hypoxia has been associated with metabolic reprogramming, immunological dysregulation, and adverse pulmonary vascular remodeling in preclinical studies. Many animal models have been developed to mimic HPH; however, many of them do not accurately represent the human disease state and may not be suitable for testing new therapeutic strategies. The scientific understanding of HPH is rapidly evolving, and recent efforts have focused on understanding the complex interplay among hypoxia, inflammation, and cellular metabolism in the development of this disease. Through continued research and the development of more sophisticated animal models, it is hoped that we will be able to gain a deeper understanding of the underlying mechanisms of HPH and implement more effective therapies for this debilitating disease.

Endothelium-dependent relaxation is impaired in Schlager hypertensive (BPH/2J) mice by region-specific mechanisms in conductance and resistance arteries.

Endothelial dysfunction and arterial stiffness are hallmarks of hypertension, and major risk factors for cardiovascular disease. BPH/2J (Schlager) mice are a genetic model of spontaneous hypertension, but little is known about the vascular pathophysiology of these mice and the region-specific differences between vascular beds. Therefore, this study compared the vascular function and structure of large conductance (aorta and femoral) and resistance (mesenteric) arteries of BPH/2J mice with their normotensive BPN/2J counterparts. Blood pressure was measured in BPH/2J and BPN/3J mice via pre-implanted radiotelemetry probes. At endpoint, vascular function and passive mechanical wall properties were assessed using wire and pressure myography, qPCR and histology. Mean arterial blood pressure was elevated in BPH/2J mice compared to BPN/3J controls. Endothelium-dependent relaxation to acetylcholine was attenuated in both the aorta and mesenteric arteries of BPH/2J mice, but through different mechanisms. In the aorta, hypertension reduced the contribution of prostanoids. Conversely, in the mesenteric arteries, hypertension reduced the contribution of both nitric oxide and endothelium-dependent hyperpolarization. Hypertension reduced volume compliance in both femoral and mesenteric arteries, but hypertrophic inward remodelling was only observed in the mesenteric arteries of BPH/2J mice. This is the first comprehensive investigation of vascular function and structural remodelling in BPH/2J mice. Overall, hypertensive BPH/2J mice exhibited endothelial dysfunction and adverse vascular remodelling in the macro- and microvasculature, underpinned by distinct region-specific mechanisms. This highlights BPH/2J mice as a highly suitable model for evaluating novel therapeutics to treat hypertension-associated vascular dysfunction.

Evaluating the effectiveness of an apelin analog as a potential treatment for pulmonary arterial hypertension using a sugen-hypoxia rat model

Background: Pulmonary arterial hypertension (PAH) is a debilitating syndrome characterized by heightened pulmonary arterial pressures, and adverse pulmonary vascular remodeling. Eventually, the right ventricle (RV) decompensates, and fatal right heart failure ensues. Existing treatments for PAH are ineffective at improving survival. Apelin is an endogenous cardioprotective peptide, and disruption of apelin signaling was associated with the development of PAH. Restoring the activity of the apelin pathway is a promising approach in reversing the arteriopathy underlying PAH to protect the RV. The salutary actions of apelin are limited by its short half-life; recently, apelin analogs designed with extended half-lives offer a novel therapeutic avenue requiring further testing. Objective: Our project aims to evaluate the effectiveness of an apelin analog as a potential treatment for PAH using a Sugen-Hypoxia (SuHx) rat model of PAH which recapitulates disease characteristics seen in humans. We hypothesize that the apelin analog treatment will improve pulmonary hemodynamics and preserve RV adaptation in rats exposed to SuHx and assuage the pulmonary arteriopathy seen in PAH rats. Experimental design: Male Sprague Dawley rats aged 9 weeks were randomly split into a placebo or treated PAH group. For 3 weeks, a control group was kept within normal room air while the placebo and treated PAH rats were kept in a hypoxia chamber (10% O 2 ). Placebo and treated rats were injected with SU5416 (20 mg/kg, SQ) once at the start of the 3 weeks to induce disease. The normoxic period lasted 5 weeks following the 3 weeks of hypoxia. Treated rats received apelin analog (0.5 μmol/kg, IV, b.i.d.) for the final 3 weeks of normoxia; the placebo group received the same dose of saline. Results: At endpoint, glomerular filtration rate (GFR) measurements showed that placebo treated (PAH-P) PAH rats had reduced GFR while apelin treated (PAH-A) PAH rats had recovered GFR. Echocardiography revealed that PAH-A rats had improved cardiac function compared to PAH-P rats. RV Pressure-volume loop surgeries showed that PAH-A rats had ameliorated RV hemodynamic pressures in contrast to PAH-P rats. Histological analysis demonstrated reduced cardiac fibrosis and hypertrophy, and fewer formations of pulmonary vascular lesions within PAH-A rats compared to PAH-P rats. Single nucleus RNA sequencing performed on RV and lung tissue delineated mitigation of disease progression within the PAH-A group compared to PAH-P rats. Electrocardiography recordings showed more severe electrical remodeling in the PAH-P group compared to the PAH-A rats. Conclusions &amp; significance: Rats with PAH treated with apelin had overall improved cardiopulmonary health outcomes compared to placebo treated PAH rats. The results of this study provide insight into the beneficial role of the apelin pathway in the setting of PAH to propose a new treatment for patients with PAH to improve their duration and quality of life. Canadian Institutes of Health Research Grant This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Homeostatic, Non-Canonical Role of Macrophage Elastase in Vascular Integrity.

Matrix metalloproteinase (MMP)-12 is highly expressed in abdominal aortic aneurysms and its elastolytic function has been implicated in the pathogenesis. This concept is challenged, however, by conflicting data. Here, we sought to revisit the role of MMP-12 in abdominal aortic aneurysm. Apoe-/- and Mmp12-/-/Apoe-/- mice were infused with Ang II (angiotensin). Expression of neutrophil extracellular traps (NETs) markers and complement component 3 (C3) levels were evaluated by immunostaining in aortas of surviving animals. Plasma complement components were analyzed by immunoassay. The effects of a complement inhibitor, IgG-FH1-5 (factor H-immunoglobulin G), and macrophage-specific MMP-12 deficiency on adverse aortic remodeling and death from rupture in Ang II-infused mice were determined. Unexpectedly, death from aortic rupture was significantly higher in Mmp12-/-/Apoe-/- mice. This associated with more neutrophils, citrullinated histone H3 and neutrophil elastase, markers of NETs, and C3 levels in Mmp12-/- aortas. These findings were recapitulated in additional models of abdominal aortic aneurysm. MMP-12 deficiency also led to more pronounced elastic laminae degradation and reduced collagen integrity. Higher plasma C5a in Mmp12-/- mice pointed to complement overactivation. Treatment with IgG-FH1-5 decreased aortic wall NETosis and reduced adverse aortic remodeling and death from rupture in Ang II-infused Mmp12-/- mice. Finally, macrophage-specific MMP-12 deficiency recapitulated the effects of global MMP-12 deficiency on complement deposition and NETosis, as well as adverse aortic remodeling and death from rupture in Ang II-infused mice. An MMP-12 deficiency/complement activation/NETosis pathway compromises aortic integrity, which predisposes to adverse vascular remodeling and abdominal aortic aneurysm rupture. Considering these new findings, the role of macrophage MMP-12 in vascular homeostasis demands re-evaluation of MMP-12 function in diverse settings.

Role of Vitamin D Deficiency in the Pathogenesis of Cardiovascular and Cerebrovascular Diseases

Deficiency in vitamin D (VitD), a lipid-soluble vitamin and steroid hormone, affects approximately 24% to 40% of the population of the Western world. In addition to its well-documented effects on the musculoskeletal system, VitD also contributes importantly to the promotion and preservation of cardiovascular health via modulating the immune and inflammatory functions and regulating cell proliferation and migration, endothelial function, renin expression, and extracellular matrix homeostasis. This brief overview focuses on the cardiovascular and cerebrovascular effects of VitD and the cellular, molecular, and functional changes that occur in the circulatory system in VitD deficiency (VDD). It explores the links among VDD and adverse vascular remodeling, endothelial dysfunction, vascular inflammation, and increased risk for cardiovascular and cerebrovascular diseases. Improved understanding of the complex role of VDD in the pathogenesis of atherosclerotic cardiovascular diseases, stroke, and vascular cognitive impairment is crucial for all cardiologists, dietitians, and geriatricians, as VDD presents an easy target for intervention.

Acute Exposure to Glycated Proteins Impaired in the Endothelium-Dependent Aortic Relaxation: A Matter of Oxidative Stress

Chronically increased levels of high molecular weight advanced glycation end products (HMW-AGEs) are known to induce cardiovascular dysfunction. Whether an acute increase in HMW-AGE levels affects vascular function remains unknown. In this study, we examined whether acute exposure to HMW-AGEs disturbs aortic vasomotor function. Aortae were obtained from healthy male rats and were acutely pre-treated with HMW-AGEs in organ baths. Aortic relaxation responses to cumulative doses of acetylcholine (ACh), in the presence or absence of superoxide dismutase (SOD), were measured after precontraction with phenylephrine (PE). Furthermore, levels of 3-nitrotyrosine were evaluated on aortic paraffine sections. In our study, we show that acute exposure to HMW-AGEs significantly decreases the aortic relaxation response to ACh. SOD pre-treatment prevents acute HMW-AGEs-induced impairment by limiting superoxide formation. In conclusion, our data demonstrate that acute exposure to HMW-AGEs causes adverse vascular remodelling, characterised by disturbed vasomotor function due to increased oxidative stress. These results create opportunities for future research regarding the acute role of HMW-AGEs in cardiovascular dysfunction.