Site Specificity of Atherosclerosis

An Endothelial Cell Is Not Simply an Endothelial Cell

Endothelial cells (ECs) are a multifaceted component of the vascular system with roles in immunity, maintaining tissue fluid balance, and vascular tone. Dysregulation or dysfunction of ECs can have far-reaching implications, leading pathologies ranging from cardiovascular diseases, such as hypertension and atherosclerosis, ischemia, chronic kidney disease, blood-brain barrier integrity, dementia, and tumor metastasis. Recent advancements in regenerative medicine have highlighted the potential of stem cell-derived ECs, particularly from induced pluripotent stem cells, to treat ischemic tissues, as well as models of vascular integrity. This review summarizes what is known in the generation of ECs with an emphasis on tissue-specific ECs and EC subphenotypes important in the development of targeted cell-based therapies for patient treatment.

A bypass flow model to study endothelial cell mechanotransduction across diverse flow environments

Disturbed flow is one of the pathological initiators of endothelial dysfunction in intimal hyperplasia (IH) which is commonly seen in vascular bypass grafts, and arteriovenous fistulas. Various in vitro disease models have been designed to simulate the hemodynamic conditions found in the vasculature. Nonetheless, prior investigations have encountered challenges in establishing a robust disturbed flow model, primarily attributed to the complex bifurcated geometries and distinctive flow dynamics. In the present study, we aim to address this gap by introducing an in vitro bypass flow model capable of inducing disturbed flow and other hemodynamics patterns through a pulsatile flow in the same model. To assess the model's validity, we employed computational fluid dynamics (CFD) to simulate hemodynamics and compared the morphology and functions of human umbilical venous endothelial cells (HUVECs) under disturbed flow conditions to those in physiological flow or stagnant conditions. CFD analysis revealed the generation of disturbed flow within the model, pinpointing the specific location in the channel where the effects of disturbed flow were observed. High-content screening, a single-cell morphological profile assessment, demonstrated that HUVECs in the disturbed flow area exhibited random orientation, and morphological features were significantly distinct compared to cells in the physiological flow or stagnant condition after a two days of flow exposure. Furthermore, HUVECs exposed to disturbed flow underwent extensive remodeling of the adherens junctions and expressed higher levels of endothelial cell activation markers compared to other hemodynamic conditions. In conclusion, our in vitro bypass flow model provides a robust platform for investigating the associations between disturbed flow pattern and vascular diseases.

Beyond Stress Ischemia: Unveiling the Multifaceted Nature of Coronary Vulnerable Plaques Using Cardiac Computed Tomography

Historically, cardiovascular prevention has been predominantly focused on stress-induced ischemia, but recent trials have challenged this paradigm, highlighting the emerging role of vulnerable, non-flow-limiting coronary plaques, leading to a shift towards integrating plaque morphology with functional data into risk prediction models. Coronary computed tomography angiography (CCTA) represents a high-resolution, low-risk, and largely available non-invasive modality for the precise delineation of plaque composition, morphology, and inflammatory activity, further enhancing our ability to stratify high-risk plaque and predict adverse cardiovascular outcomes. Coronary artery calcium (CAC) scoring, derived from CCTA, has emerged as a promising tool for predicting future cardiovascular events in asymptomatic individuals, demonstrating incremental prognostic value beyond traditional cardiovascular risk factors in terms of myocardial infarction, stroke, and all-cause mortality. Additionally, CCTA-derived information on adverse plaque characteristics, geometric characteristics, and hemodynamic forces provides valuable insights into plaque vulnerability and seems promising in guiding revascularization strategies. Additionally, non-invasive assessments of epicardial and pericoronary adipose tissue (PCAT) further refine risk stratification, adding prognostic significance to coronary artery disease (CAD), correlating with plaque development, vulnerability, and rupture. Moreover, CT imaging not only aids in risk stratification but is now emerging as a screening tool able to monitor CAD progression and treatment efficacy over time. Thus, the integration of CAC scoring and PCAT evaluation into risk stratification algorithms, as well as the identification of high-risk plaque morphology and adverse geometric and hemodynamic characteristics, holds promising results for guiding personalized preventive interventions, helping physicians in identifying high-risk individuals earlier, tailoring lifestyle and pharmacological interventions, and improving clinical outcomes in their patients.

Introducing a Novel Innovative Technique for the Recording and Interpretation of Dynamic Coronary Angiography

In the study of coronary artery disease (CAD), the mechanism of plaque formation and development is still an important subject for investigation. A limitation of current coronary angiography (CAG) is that it can only show static images of the narrowing of arterial channels without identifying the mechanism of the disease or predicting its progression or regression. To address this limitation, the CAG technique has been modified. The new approach emphasizes identifying and analyzing blood flow patterns, employing methodologies akin to those used by hydraulic engineers for fluid or gas movement through domestic or industrial pipes and pumps. With the new technique, various flow patterns and arterial phenomena-such as laminar, turbulent, antegrade, retrograde, and recirculating flow and potentially water hammer shock and vortex formation-are identified, recorded, and classified. These phenomena are then correlated with the presence of lesions at different locations within the coronary vasculature. The formation and growth of these lesions are explained from the perspective of fluid mechanics. As the pathophysiology of CAD and other cardiovascular conditions becomes clearer, new medical, surgical, and interventional treatments could be developed to reverse abnormal coronary flow dynamics and restore laminar flow, leading to improved clinical outcomes.

Insights from Murine Studies on the Site Specificity of Atherosclerosis

Atherosclerosis is an inflammatory reaction that develops at specific regions within the artery wall and at specific sites of the arterial tree over a varying time frame in response to a variety of risk factors. The mechanisms that account for the interaction of systemic factors and atherosclerosis-susceptible regions of the arterial tree to mediate this site-specific development of atherosclerosis are not clear. The dynamics of blood flow has a major influence on where in the arterial tree atherosclerosis develops, priming the site for interactions with atherosclerotic risk factors and inducing cellular and molecular participants in atherogenesis. But how this accounts for lesion development at various locations along the vascular tree across differing time frames still requires additional study. Currently, murine models are favored for the experimental study of atherogenesis and provide the most insight into the mechanisms that may contribute to the development of atherosclerosis. Based largely on these studies, in this review, we discuss the role of hemodynamic shear stress, SR-B1, and other factors that may contribute to the site-specific development of atherosclerosis.

Modelling lower-limb peripheral arterial disease using clinically available datasets: impact of inflow boundary conditions on hemodynamic indices for restenosis prediction

BACKGROUND AND OBJECTIVES

The integration of hemodynamic markers as risk factors in restenosis prediction models for lower-limb peripheral arteries is hindered by fragmented clinical datasets. Computed tomography (CT) scans enable vessel geometry reconstruction and can be obtained at different times than the Doppler ultrasound (DUS) images, which provide information on blood flow velocity. Computational fluid dynamics (CFD) simulations allow the computation of near-wall hemodynamic indices, whose accuracy depends on the prescribed inlet boundary condition (BC), derived from the DUS images. This study aims to: (i) investigate the impact of different DUS-derived velocity waveforms on CFD results; (ii) test whether the same vessel areas, subjected to altered hemodynamics, can be detected independently of the applied inlet BC; (iii) suggest suitable DUS images to obtain reliable CFD results.

METHODS

CFD simulations were conducted on three patients treated with bypass surgery, using patient-specific DUS-derived inlet BCs recorded at either the same or different time points than the CT scan. The impact of the chosen inflow condition on bypass hemodynamics was assessed in terms of wall shear stress (WSS)-derived quantities. Patient-specific critical thresholds for the hemodynamic indices were applied to identify critical luminal areas and compare the results with a reference obtained with a DUS image acquired in close temporal proximity to the CT scan.

RESULTS

The main findings indicate that: (i) DUS-derived inlet velocity waveforms acquired at different time points than the CT scan led to statistically significantly different CFD results (p<0.001); (ii) the same luminal surface areas, exposed to low time-averaged WSS, could be identified independently of the applied inlet BCs; (iii) similar outcomes were observed for the other hemodynamic indices if the prescribed inlet velocity waveform had the same shape and comparable systolic acceleration time to the one recorded in close temporal proximity to the CT scan.

CONCLUSIONS

Despite a lack of standardised data collection for diseased lower-limb peripheral arteries, an accurate estimation of luminal areas subjected to altered near-wall hemodynamics is possible independently of the applied inlet BC. This holds if the applied inlet waveform shares some characteristics - derivable from the DUS report - as one matching the acquisition time of the CT scan.

Low shear stress-induced blockage of autophagic flux impairs endothelial barrier and facilitates atherosclerosis in mice

Atherosclerosis preferentially occurs in areas with low shear stress (LSS) and oscillatory flow. LSS has been demonstrated to correlate with the development of atherosclerosis. The sphingosine 1-phosphate receptor 1 (S1PR1), involving intravascular blood flow sensing, regulates vascular development and vascular barrier function. However, whether LSS affects atherosclerosis via regulating S1PR1 remains incompletely clear. In this study, immunostaining results of F-actin, β-catenin, and VE-cadherin indicated that LSS impaired endothelial barrier function in human umbilical vein endothelial cells (HUVECs). Western blot analysis showed that LSS resulted in blockage of autophagic flux in HUVECs. In addition, autophagy agonist Rapamycin (Rapa) antagonized LSS-induced endothelial barrier dysfunction, whereas autophagic flux inhibitor Bafilomycin A1 (BafA1) exacerbated it, indicating that LSS promoted endothelial barrier dysfunction by triggering autophagic flux blockage. Notably, gene expression analysis revealed that LSS downregulated S1PR1 expression, which was antagonized by Rapa. Selective S1PR1 antagonist W146 impaired endothelial barrier function of HUVECs under high shear stress (HSS) conditions. Moreover, our data showed that expression of GAPARAPL2, a member of autophagy-related gene 8 (Atg8) proteins, was decreased in HUVECs under LSS conditions. Autophagic flux blockage induced by GAPARAPL2 knockdown inhibited S1PR1, aggravated endothelial barrier dysfunction of HUVECs in vitro, and promoted aortic atherosclerosis in ApoE-/- mice in vivo. Our study demonstrates that autophagic flux blockage induced by LSS downregulates S1PR1 expression and impairs endothelial barrier function. GABARAPL2 inhibition is involved in LSS-induced autophagic flux blockage, which impairs endothelial barrier function via downregulation of S1PR1.

Polyvascular Disease: A Narrative Review of Risk Factors, Clinical Outcomes and Treatment

PURPOSE OF REVIEW

Polyvascular disease has a significant global burden and is associated with increased risk of major adverse cardiac events with each additional vascular territory involved. The purpose of this review is to highlight the risk factors, associated outcomes, emerging genetic markers, and evidence for screening and treatment of polyvascular disease.

RECENT FINDINGS

Polyvascular disease is the presence of atherosclerosis in two or more vascular beds. It has a significant global burden, with a prevalence of 30-70% in patients with known atherosclerosis. Patients with polyvascular disease experience elevated rates of cardiovascular death, myocardial infarction and stroke, especially among high-risk subgroups like those with type 2 diabetes mellitus and there is a step-wise increased risk of adverse outcomes with each additional vascular territory involved. Genetic analyses demonstrate that some individuals may carry a genetic predisposition, while others exhibit higher levels of atherogenic lipoproteins and inflammatory markers. Routine screening for asymptomatic disease is not currently recommended by major cardiovascular societies unless patients are high-risk. While there are no established protocols for escalating treatment, existing guidelines advocate for lipid-lowering therapy. Additionally, recent studies have demonstrated benefit from antithrombotic agents, such as P2Y12 inhibitors and low-dose anticoagulation, but the optimal timing and dosage of these agents has not been established, and the ischemic benefit must be balanced against the increased risk of bleeding in the polyvascular population. Due to the high prevalence and risks associated with polyvascular disease, early identification and treatment intensification are crucial to reduce disease progression. Future research is needed to develop screening protocols and determine the optimal timing and dosing of therapy to prevent ischemic events.

Associations between Total Atherosclerosis Burden of Baroreceptor-Resident Arteries and ECG Abnormalities after Acute Ischemic Stroke

Electrocardiogram (ECG) abnormalities are the most common cardiac complications after acute ischemic stroke (AIS) and predict poor outcomes. The arterial baroreflex is an essential determinant of cardiovascular autonomic regulation, with receptors mainly residing in carotid sinuses and aortic arch. The atherosclerosis of these baroreceptor-resident arteries (BRA) is very common in AIS patients and might impair baroreflex function. However, the associations between the atherosclerosis of BRA and ECG abnormalities after AIS are still unknown. In total, 228 AIS patients within 7 days after onset without a pre-existing heart disease were prospectively recruited. With computed tomography angiography, atherosclerosis conditions in 10 segments of the carotid sinuses and aortic arch were scored and summed as the Total Atherosclerosis Burden of BRA (TAB-BRA), and asymptomatic coronary artery stenosis (ACAS) ≥50% was simultaneously assessed. We performed 12-lead ECG to dynamically detect abnormal repolarization, and 24 h Holter ECG to monitor arrhythmias and heart rate variability (HRV) parameters, which are reliable indicators to assess cardiac autonomic function. We found that TAB-BRA was positively associated with abnormal repolarization (OR 1.09; CI% 1.03-1.16; p = 0.003) and serious cardiac arrhythmias (OR 1.08; CI% 1.01-1.15; p = 0.021). In addition, TAB-BRA was an important predictor of abnormal repolarization, persisting over 3 days (OR 1.17; CI% 1.05-1.30; p = 0.003). However, ACAS ≥ 50% did not relate to these ECG abnormalities. TAB-BRA was negatively correlated with parasympathetic-related HRV parameters. Our results indicated that AIS patients with a high TAB-BRA are more likely to have ECG abnormalities and delayed normalization, which may relate to the decreased cardiac parasympathetic activity, but not the accompanied ACAS ≥ 50%.

Repeated Injection of Very Small Superparamagnetic Iron Oxide Particles (VSOPs) in Murine Atherosclerosis: A Safety Study

Citrate-coated electrostatically stabilized very small superparamagnetic iron oxide particles (VSOPs) have been successfully tested as magnetic resonance angiography (MRA) contrast agents and are promising tools for molecular imaging of atherosclerosis. Their repeated use in the background of pre-existing hyperlipidemia and atherosclerosis has not yet been studied. This study aimed to investigate the effect of multiple intravenous injections of VSOPs in atherosclerotic mice. Taurine-formulated VSOPs (VSOP-T) were repeatedly intravenously injected at 100 µmol Fe/kg in apolipoprotein E-deficient (ApoE KO) mice with diet-induced atherosclerosis. Angiographic imaging was carried out by in vivo MRI. Magnetic particle spectrometry was used to detect tissue VSOP content, and tissue iron content was quantified photometrically. Pathological changes in organs, atherosclerotic plaque development, and expression of hepatic iron-related proteins were evaluated. VSOP-T enabled the angiographic imaging of heart and blood vessels with a blood half-life of one hour. Repeated intravenous injection led to VSOP deposition and iron accumulation in the liver and spleen without affecting liver and spleen pathology, expression of hepatic iron metabolism proteins, serum lipids, or atherosclerotic lesion formation. Repeated injections of VSOP-T doses sufficient for MRA analyses had no significant effects on plaque burden, steatohepatitis, and iron homeostasis in atherosclerotic mice. These findings underscore the safety of VSOP-T and support its further development as a contrast agent and molecular imaging tool.

HEG1 Protects Against Atherosclerosis by Regulating Stable Flow-Induced KLF2/4 Expression in Endothelial Cells

BACKGROUND

Atherosclerosis preferentially occurs in arterial regions of disturbed blood flow, and stable flow (s-flow) protects against atherosclerosis by incompletely understood mechanisms.

METHODS

Our single-cell RNA-sequencing data using the mouse partial carotid ligation model was reanalyzed, which identified Heart-of-glass 1 (HEG1) as an s-flow-induced gene. HEG1 expression was studied by immunostaining, quantitive polymerase chain reaction, hybridization chain reaction, and Western blot in mouse arteries, human aortic endothelial cells (HAECs), and human coronary arteries. A small interfering RNA-mediated knockdown of HEG1 was used to study its function and signaling mechanisms in HAECs under various flow conditions using a cone-and-plate shear device. We generated endothelial-targeted, tamoxifen-inducible HEG1 knockout (HEG1iECKO) mice. To determine the role of HEG1 in atherosclerosis, HEG1iECKO and littermate-control mice were injected with an adeno-associated virus-PCSK9 [proprotein convertase subtilisin/kexin type 9] and fed a Western diet to induce hypercholesterolemia either for 2 weeks with partial carotid ligation or 2 months without the surgery.

RESULTS

S-flow induced HEG1 expression at the mRNA and protein levels in vivo and in vitro. S-flow stimulated HEG1 protein translocation to the downstream side of HAECs and release into the media, followed by increased messenger RNA and protein expression. HEG1 knockdown prevented s-flow-induced endothelial responses, including monocyte adhesion, permeability, and migration. Mechanistically, HEG1 knockdown prevented s-flow-induced KLF2/4 (Kruppel-like factor 2/4) expression by regulating its intracellular binding partner KRIT1 (Krev interaction trapped protein 1) and the MEKK3-MEK5-ERK5-MEF2 pathway in HAECs. Compared with littermate controls, HEG1iECKO mice exposed to hypercholesterolemia for 2 weeks and partial carotid ligation developed advanced atherosclerotic plaques, featuring increased necrotic core area, thin-capped fibroatheroma, inflammation, and intraplaque hemorrhage. In a conventional Western diet model for 2 months, HEG1iECKO mice also showed an exacerbated atherosclerosis development in the arterial tree in both sexes and the aortic sinus in males but not in females. Moreover, endothelial HEG1 expression was reduced in human coronary arteries with advanced atherosclerotic plaques.

CONCLUSIONS

Our findings indicate that HEG1 is a novel mediator of atheroprotective endothelial responses to flow and a potential therapeutic target.

Characterization of Atherosclerotic Mice Reveals a Sex-Dependent Susceptibility to Plaque Calcification but No Major Changes in the Lymphatics in the Arterial Wall

Lymphatics participate in reverse cholesterol transport, and their presence in the arterial wall of the great vessels and prior experimental results suggest their possible role in the development of atherosclerosis. The aim of this study was to characterize the lymphatic vasculature of the arterial wall in atherosclerosis. Tissue sections and tissue-cleared aortas of wild-type mice unveiled significant differences in the density of the arterial lymphatic network throughout the arterial tree. Male and female Ldlr-/- and ApoE-/- mice on a Western diet showed sex-dependent differences in plaque formation and calcification. Female mice on a Western diet developed more calcification of atherosclerotic plaques than males. The lymphatic vessels within the aortic wall of these mice showed no major changes regarding the number of lymphatic junctions and end points or the lymphatic area. However, female mice on a Western diet showed moderate dilation of lymphatic vessels in the abdominal aorta and exhibited indications of increased peripheral lymphatic function, findings that require further studies to understand the role of lymphatics in the arterial wall during the development of atherosclerosis.

Low shear stress exacerbates atherosclerosis by inducing the generation of neutrophil extracellular traps via Piezo1-mediated mechanosensation

BACKGROUND AND AIMS

Atherosclerosis is a chronic lipid-driven inflammatory disease largely influenced by hemodynamics. Neutrophil extracellular trap (NET)-mediated inflammation plays an important role in atherosclerosis. However, little is known about the relationship between low shear stress (LSS) and NET generation, as well as the underlying mechanism.

METHODS

We induced LSS by partial ligation of the left carotid artery in high-fat diet-fed male ApoE-/- mice. To further validate the direct relationship between LSS and NET formation invitro, differentiated human promyelocytic leukemia HL-60 cells and bone marrow-derived neutrophils were suspended in fluid flow under normal or low shear stress using a parallel-plate flow chamber system.

RESULTS

Four weeks after surgery, ligated carotid arteries had more lipid deposition, larger plaque area, and increased NET formation than unligated arteries. Inhibition of NETosis could significantly reduce plaque formation in ApoE-/- mice. Invitro, LSS could promote NET generation directly through downregulation of Piezo1, a mechanosensitive ion channel. Downregulation of Piezol could activate neutrophils and promote NETosis in static conditions. Conversely, Yoda1-evoked activation of Piezo1 attenuated LSS-induced NETosis. Mechanistically, downregulation of Piezo1 resulted in decreased Ca2+ influx and increased histone deacetylase 2 (HDAC2), which increased reactive oxygen species levels and led to NETosis. LSS-induced NET generation also promoted apoptosis and adherence of endothelial cells.

CONCLUSION

LSS directly promotes NETosis through the Piezo1-HDAC2 axis in atherosclerosis progression. This study uncovers the essential role of Piezo1-mediated mechanical signaling in NET generation and plaque formation, which provides a promising therapeutic strategy for atherosclerosis.

Trapdoor endarterectomy for coral reef plaque of the paravisceral aorta in the modern era

Coral reef atherosclerosis of the paravisceral aorta is a rare disease whose description is confined to before contemporary vascular surgical techniques. This study aims to describe the characteristics and outcomes of patients with coral reef aorta treated with trapdoor endarterectomy at a single high-volume quaternary referral center since 2010. From 2010 to 2022, 14 patients with coral reef aorta were treated with trapdoor endarterectomy. The patient data were obtained via a retrospective medical record review. The patients were predominantly women (79%) with a median age of 65 years (interquartile range [IQR], 60-70 years). The patients universally had a tobacco smoking history and hypertension. More than 85% had previously diagnosed carotid stenosis. Two patients (14%) had undergone prior aortofemoral reconstruction, and one patient (7%) had undergone prior axillobifemoral bypass. The most common presenting symptoms were claudication (71%), chronic mesenteric ischemia (50%), and renovascular hypertension (43%). Of the 14 patients, 8 (57%) underwent isolated endarterectomy and 6 (43%) underwent concomitant aortobifemoral bypass. In addition, 13 patients (93%) required a supraceliac aortic clamp position with a median clamp time of 23 minutes (IQR, 20-30 minutes). The median estimated blood loss was 1650 mL (IQR, 1025-3000 mL). A cell saver was used in 13 procedures (93%), with a median transfusion of 563 mL (IQR, 231-900 mL). The median operative time was 341 minutes (IQR, 315-416 minutes). Eight patients (57%) experienced acute kidney injury in the postoperative period with a peak creatinine of 1.96 mg/dL (IQR, 1.50-2.84 mg/dL). The median length of stay was 11 days (IQR, 6-16 days), with an intensive care unit stay of 4 days (IQR, 2-7 days). One patient (7%) required reoperation in the immediate perioperative period for a retroperitoneal hematoma. The postoperative ankle brachial index increased from a median of 0.58 (right) and 0.57 (left) bilaterally in the preoperative period to 1.09 (right) and 1.10 (left) postoperatively. Eight patients (57%) had follow-up data available for >2 years postoperatively, with five patients (36%) having follow-up data available for >3 years. Two major adverse cardiac events were reported at the last follow-up. One patient reported mild recurrent symptoms of chronic mesenteric ischemia during 3 years of postoperatively, with no concurrent imaging findings or loss of patency found on computed tomography angiography. Symptomatic coral reef atherosclerosis of the paravisceral aorta is a complex disease rarely encountered even at high-volume referral centers. These patients can be expected to experience short-term postoperative morbidity and require intensive care. Despite these challenges, trapdoor endarterectomy is a safe and effective procedure for coral reef aorta, and most patients achieve dramatic symptomatic improvement with durable results.

Evaluating Total Atherosclerosis Burden of Baroreceptor-Resident Arteries after Ischemic Cerebrovascular Disease for Identifying Patients with Heavy Coronary Atherosclerosis Burden

AIM

The carotid sinuses and aortic arch are baroreceptor-resident arteries (BRAs) and atherosclerosis-susceptible sites of brain-supplying arteries, which would impair baroreflex-mediated blood pressure (BP) regulation and prompt coronary atherosclerosis. We sought to determine the relationship between total atherosclerosis burden (TAB) of BRAs and coronary atherosclerosis burden (AB) in patients with ischemic cerebrovascular disease (ICVD) and explore the potential contribution of BP profiles to this relationship.

METHODS

In this cross-sectional analysis of patients with ICVD who simultaneously undertook computed tomography angiography and 24-hour ambulatory BP monitoring, TAB of BRAs was scored based on the atherosclerotic vessel circumference ratio of the carotid sinuses and aortic arch, while the ABs of the intracranial, cervical, aortic, and coronary arteries were scored based on stenosis severity and plaque complexity as routine.

RESULTS

Among the 230 patients analyzed, coronary AB was significantly correlated with TAB of BRAs, independently of, and more tightly than the ABs of the intracranial, cervical, and aortic arteries, and the stenosis- and complexity-based AB of BRA-located arteries (bilateral common and extracranial internal carotid arteries and aortic arch). Both coronary AB and TAB of BRAs were negatively associated with the night-to-day BP dipping ratios, which was quite different from the relationship between intracranial AB and 24-hour BP characteristics. These findings were also true for patients with ICVD without a history of coronary artery disease.

CONCLUSION

Evaluating TAB of BRAs might provide a new link between atherosclerosis of brain- and heart-supplying arteries, connected partially by BP circadian rhythm. It might facilitate identifying patients with ICVD with heavy coronary AB and comprehensively managing vascular risk.

The effects of glycosylation modifications on monocyte recruitment and foam cell formation in atherosclerosis

The monocyte recruitment and foam cell formation have been intensively investigated in atherosclerosis. Nevertheless, as the study progressed, it was obvious that crucial molecules participated in the monocyte recruitment and the membrane proteins in macrophages exhibited substantial glycosylation modifications. These modifications can exert a significant influence on protein functions and may even impact the overall progression of diseases. This article provides a review of the effects of glycosylation modifications on monocyte recruitment and foam cell formation. By elaborating on these effects, we aim to understand the underlying mechanisms of atherogenesis further and to provide new insights into the future treatment of atherosclerosis.

Innominate artery occlusion: a case study

Aim of the study

The aim of this case report is to evaluate carotid duplex and hemodynamic patterns in an asymptomatic male patient with innominate artery occlusion. Innominate artery occlusion is a rare clinical entity that can lead to a range of cerebrovascular symptoms, including arm claudication, subclavian steal syndrome, and stroke. The case report emphasizes key learning points in diagnosing innominate artery occlusion using imaging and physiological methods.

Case description

A 64-year-old asymptomatic male patient with a history of carotid bruit, hypertension, coronary artery bypass grafting, aortic aneurysm, hyperlipidemia, mild aortic stenosis, long-term tobacco use, and a body mass index of 24 was referred for a carotid ultrasound.

Conclusions

Innominate artery occlusion is a rare condition requiring a comprehensive assessment of collateralization before any intervention is attempted. Considering waveform features such as transient end-diastolic flow reversal and tardus parvus, along with brachial pressures and transcranial Doppler, can assist in evaluating the extent of disease.

Pitavastatin in the Prevention of Cardiovascular Disease in People Living with HIV: A Review

HIV is associated with a wide array of pathophysiologic mechanisms that ultimately contribute to mortality. While HIV is traditionally known as a disease that attacks the immune system, it is now established that infection with HIV can cause cardiovascular disease (CVD). Through inflammation, atherogenesis, interactions with antiretroviral therapy/highly-active antiretroviral therapy (ART/HAART), and other mechanisms, HIV is an independent risk factor for the development of CVD. The treatment of the CVD risks associated with HIV is complicated, especially due to interactions with hyperlipidemic drugs and ART/HAART. There is a prompt need for a drug (or drug class) that is known to reduce the risk of CVD, specifically in people living with HIV. Recently, the randomized trial to prevent vascular events in HIV trial evaluated the usage of pitavastatin in preventing major cardiac events in people with HIV, showing a significant reduction in cardiac events among those taking the therapeutic. In this review, we evaluate the mechanisms by which HIV contributes to CVD, and the randomized trial to prevent vascular events in HIV trial, and postulate about future directions of the drug in treating people living with HIV.

The Determinants of Elevated Pathobiological Determination of Atherosclerosis in Youth Risk Score in Perinatally HIV-Infected Adolescents in South Africa

BACKGROUND

Youth living with perinatally acquired HIV infection (YLPHIV) are at risk of developing atherosclerotic cardiovascular disease.

METHODS

We determined the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) coronary arteries (CA) and abdominal aorta (AA) risk scores among YLPHIV who are ≥15 years old in Cape Town Adolescent and Antiretroviral Cohort. PDAY score was calculated using non-high-density lipoprotein, high-density lipoprotein cholesterol, hyperglycemia, hypertension, obesity, and smoking; a score ≥1 was considered elevated. HIV viremia was categorized as sustained (SV) = viral load (VL) >50 copies/mL, transient (TV) = mix of VL >50 and ≤50 copies/mL, or sustained-virologic suppression = VL <50 copies/mL throughout the study. Among YLPHIV, logistic models were fit to assess factors associated with elevated PDAY.

RESULTS

Overall, 218 YLPHIV [median age 16.8 (interquartile range: 15.9-17.8) years, male 47%] were included. Among YLPHIV, 8% (n = 17) had SV, and 54% (n = 118) had TV. Median antiretroviral therapy (ART) duration was 12 (interquartile range: 8-14) years. Among YLPHIV, 30.3% and 18.4% had elevated PDAY for CA and AA, respectively.Among YLPHIV, SV [adjusted odds ratio (aOR) = 18.4, P < 0.01] and TV (aOR = 2.10, P = 0.04) compared with virologic suppression and ART duration in years (aOR = 1.12, P = 0.03) were associated with elevated CA. Male sex was associated with both elevated CA and AA (aOR = 2.14, P = 0.02, and aOR = 3.43, P = 0.01, respectively) and association of SV with elevated AA (aOR = 3.24, P = 0.09).

CONCLUSIONS

A substantial proportion of YLPHIV have PDAY scores reflecting increased aggregate atherosclerotic risk. Among YLPHIV, viremia, lifetime ART duration, and male sex contribute to this risk, highlighting the importance of HIV control and the need to monitor cardiometabolic health.

Protective role of perivascular adipose tissue in the cardiovascular system

This review provides an overview of the key role played by perivascular adipose tissue (PVAT) in the protection of cardiovascular health. PVAT is a specific type of adipose tissue that wraps around blood vessels and has recently emerged as a critical factor for maintenance of vascular health. Through a profound exploration of existing research, this review sheds light on the intricate structural composition and cellular origins of PVAT, with a particular emphasis on combining its regulatory functions for vascular tone, inflammation, oxidative stress, and endothelial function. The review then delves into the intricate mechanisms by which PVAT exerts its protective effects, including the secretion of diverse adipokines and manipulation of the renin-angiotensin complex. The review further examines the alterations in PVAT function and phenotype observed in several cardiovascular diseases, including atherosclerosis, hypertension, and heart failure. Recognizing the complex interactions of PVAT with the cardiovascular system is critical for pursuing breakthrough therapeutic strategies that can target cardiovascular disease. Therefore, this review aims to augment present understanding of the protective role of PVAT in cardiovascular health, with a special emphasis on elucidating potential mechanisms and paving the way for future research directions in this evolving field.

Role of vascular smooth muscle cell clonality in atherosclerosis

Atherosclerotic cardiovascular disease remains the leading cause of death worldwide. While many cell types contribute to the growing atherosclerotic plaque, the vascular smooth muscle cell (SMC) is a major contributor due in part to its remarkable plasticity and ability to undergo phenotype switching in response to injury. SMCs can migrate into the fibrous cap, presumably stabilizing the plaque, or accumulate within the lesional core, possibly accelerating vascular inflammation. How SMCs expand and react to disease stimuli has been a controversial topic for many decades. While early studies relying on X-chromosome inactivation were inconclusive due to low resolution and sensitivity, recent advances in multi-color lineage tracing models have revitalized the concept that SMCs likely expand in an oligoclonal fashion during atherogenesis. Current efforts are focused on determining whether all SMCs have equal capacity for clonal expansion or if a "stem-like" progenitor cell may exist, and to understand how constituents of the clone decide which phenotype they will ultimately adopt as the disease progresses. Mechanistic studies are also beginning to dissect the processes which confer cells with their overall survival advantage, test whether these properties are attributable to intrinsic features of the expanding clone, and define the role of cross-talk between proliferating SMCs and other plaque constituents such as neighboring macrophages. In this review, we aim to summarize the historical perspectives on SMC clonality, highlight unanswered questions, and identify translational issues which may need to be considered as therapeutics directed against SMC clonality are developed as a novel approach to targeting atherosclerosis.

Flow-induced reprogramming of endothelial cells in atherosclerosis

Atherosclerotic diseases such as myocardial infarction, ischaemic stroke and peripheral artery disease continue to be leading causes of death worldwide despite the success of treatments with cholesterol-lowering drugs and drug-eluting stents, raising the need to identify additional therapeutic targets. Interestingly, atherosclerosis preferentially develops in curved and branching arterial regions, where endothelial cells are exposed to disturbed blood flow with characteristic low-magnitude oscillatory shear stress. By contrast, straight arterial regions exposed to stable flow, which is associated with high-magnitude, unidirectional shear stress, are relatively well protected from the disease through shear-dependent, atheroprotective endothelial cell responses. Flow potently regulates structural, functional, transcriptomic, epigenomic and metabolic changes in endothelial cells through mechanosensors and mechanosignal transduction pathways. A study using single-cell RNA sequencing and chromatin accessibility analysis in a mouse model of flow-induced atherosclerosis demonstrated that disturbed flow reprogrammes arterial endothelial cells in situ from healthy phenotypes to diseased ones characterized by endothelial inflammation, endothelial-to-mesenchymal transition, endothelial-to-immune cell-like transition and metabolic changes. In this Review, we discuss this emerging concept of disturbed-flow-induced reprogramming of endothelial cells (FIRE) as a potential pro-atherogenic mechanism. Defining the flow-induced mechanisms through which endothelial cells are reprogrammed to promote atherosclerosis is a crucial area of research that could lead to the identification of novel therapeutic targets to combat the high prevalence of atherosclerotic disease.

Role of secondary flows in coronary artery bifurcations before and after stenting: What is known so far?

Coronary arteries are uniformly exposed to traditional cardiovascular risk factors. However, atherosclerotic lesions occur in preferential regions of the coronary tree, especially in areas with disturbed local blood flow, such as coronary bifurcations. Over the latest years, secondary flows have been linked to the inception and progression of atherosclerosis. Most of these novel findings have been obtained in the field of computational fluid dynamic (CFD) analysis and biomechanics but remain poorly understood by cardiovascular interventionalists, despite the important impact that they may have in clinical practice. We aimed to summarize the current available data regarding the pathophysiological role of secondary flows in coronary artery bifurcation, providing an interpretation of these findings from an interventional perspective.

A systematic review of clinical and biomechanical engineering perspectives on the prediction of restenosis in coronary and peripheral arteries

Objective

Restenosis is a significant complication of revascularization treatments in coronary and peripheral arteries, sometimes necessitating repeated intervention. Establishing when restenosis will happen is extremely difficult due to the interplay of multiple variables and factors. Standard clinical and Doppler ultrasound scans surveillance follow-ups are the only tools clinicians can rely on to monitor intervention outcomes. However, implementing efficient surveillance programs is hindered by health care system limitations, patients' comorbidities, and compliance. Predictive models classifying patients according to their risk of developing restenosis over a specific period will allow the development of tailored surveillance, prevention programs, and efficient clinical workflows. This review aims to: (1) summarize the state-of-the-art in predictive models for restenosis in coronary and peripheral arteries; (2) compare their performance in terms of predictive power; and (3) provide an outlook for potentially improved predictive models.

Methods

We carried out a comprehensive literature review by accessing the PubMed/MEDLINE database according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The search strategy consisted of a combination of keywords and included studies focusing on predictive models of restenosis published between January 1993 and April 2023. One author independently screened titles and abstracts and checked for eligibility. The rest of the authors independently confirmed and discussed in case of any disagreement. The search of published literature identified 22 studies providing two perspectives-clinical and biomechanical engineering-on restenosis and comprising distinct methodologies, predictors, and study designs. We compared predictive models' performance on discrimination and calibration aspects. We reported the performance of models simulating reocclusion progression, evaluated by comparison with clinical images.

Results

Clinical perspective studies consider only routinely collected patient information as restenosis predictors. Our review reveals that clinical models adopting traditional statistics (n = 14) exhibit only modest predictive power. The latter improves when machine learning algorithms (n = 4) are employed. The logistic regression models of the biomechanical engineering perspective (n = 2) show enhanced predictive power when hemodynamic descriptors linked to restenosis are fused with a limited set of clinical risk factors. Biomechanical engineering studies simulating restenosis progression (n = 2) are able to capture its evolution but are computationally expensive and lack risk scoring for individual patients at specific follow-ups.

Conclusions

Restenosis predictive models, based solely on routine clinical risk factors and using classical statistics, inadequately predict the occurrence of restenosis. Risk stratification models with increased predictive power can be potentially built by adopting machine learning techniques and incorporating critical information regarding vessel hemodynamics arising from biomechanical engineering analyses.

Development of a Model for Plaque Induction in Rat Carotid Arteries

Objective  Plaque induction through intimal injury using a balloon catheter in small animals and by artificial ligation of the carotid artery in large animals have been reported. However, these reports have not yet succeeded in inducing stable plaques nor creating a high degree of intimal thickening to be used as animal models. We have previously developed a plaque induction model in rats but have failed to obtain a plaque incidence frequency that can be used as a model. Thus, in the current study, we aimed to create a versatile disease model to examine the pharmacokinetics of drug administration, determine the efficacy of treatment, and examine the process of intimal thickening. We also attempted to create an improved model with shorter, more frequent, and more severe intimal thickening. Materials and Methods  The common carotid artery of male Wistar rats was surgically exposed and completely ligated with a wire and 6-0 nylon thread. Then, the wire was removed to create a partial ligation. To create a high frequency and high degree of intimal thickening, 72 rats were divided into two groups: a single lesion group with a 0.25-mm wire and a single ligature point, and a tandem lesion group with a 0.3-mm wire and two ligature points. Each group was further divided into normal diet and high cholesterol diet groups. The presence and frequency of intimal thickening were examined for each group after 4, 8, and 16 weeks of growth. Results  In the single lesion group, intimal thickening was observed in 42% of the 4-week group and 75% of the 8-week group. In the tandem lesion group, intimal thickening was observed in 75% of the 4-week group and 50% of the 8-week group. In addition, 50% of the individuals reared for 16 weeks developed intimal thickening. Conclusion  We successfully induced intimal thickening in the carotid arteries of rats with high frequency in the single lesion and tandem lesion groups. The results also showed that the tandem lesion group tended to induce intimal thickening earlier than the single lesion group.

Role of Circular RNAs in Atherosclerosis through Regulation of Inflammation, Cell Proliferation, Migration, and Apoptosis: Focus on Atherosclerotic Cerebrovascular Disease

Atherosclerosis (AS) is a disease dangerous to human health and the main pathological cause of ischemic cardiovascular diseases. Although its pathogenesis is not fully understood, numerous basic and clinical studies have shown that AS is a chronic inflammatory disease existing in all stages of atherogenesis. It may be a common link or pathway in the pathogenesis of multiple atherogenic factors. Inflammation is associated with AS complications, such as plaque rupture and ischemic cerebral infarction. In addition to inflammation, apoptosis plays an important role in AS. Apoptosis is a type of programmed cell death, and different apoptotic cells have different or even opposite roles in the process of AS. Unlike linear RNA, circular RNA (circRNA) a covalently closed circular non-coding RNA, is stable and can sponge miRNA, which can affect the stages of AS by regulating downstream pathways. Ultimately, circRNAs play very important roles in AS by regulating inflammation, apoptosis, and some other mechanisms. The study of circular RNAs can provide new ideas for the prediction, prevention, and treatment of AS.

Differences in left and right carotid plaque vulnerability in patients with bilateral carotid plaques: a CARE-II study

BACKGROUND AND PURPOSE

Atherosclerosis is a very complex process influenced by various systemic and local factors. Therefore, in patients with bilateral carotid plaques (BCPs), there may be differences in carotid plaque vulnerability between the sides. We aimed to investigate the differences in BCP characteristics in patients with BCPs using magnetic resonance vessel wall imaging (MR-VWI).

METHODS

Participants with BCPs were selected for subanalysis from a multicentre study of Chinese Atherosclerosis Risk Evaluation II. We measured carotid plaque burden, identified each plaque component and measured their volume or area bilaterally on MR-VWI. Paired comparisons of the burden and components of BCPs were performed.

RESULTS

In all, 540 patients with BCPs were eligible for analysis. Compared with the right carotid artery (CA), larger mean lumen area (p<0.001), larger mean wall area (p=0.025), larger mean total vessel area (p<0.001) and smaller normalised wall index (p=0.006) were found in the left CA. Regarding plaque components, only the prevalence of lipid-rich necrotic core (LRNC) in the left CA was higher (p=0.026). For patients with a vulnerable plaque component coexisting on both sides, only the intraplaque haemorrhage (IPH) volume (p=0.011) was significantly greater in the left CA than in the right CA.

CONCLUSIONS

There were asymmetries in plaque growth and evolution between BCPs. The left carotid plaques were more likely to have larger plaque burden, higher prevalence of LRNC and greater IPH volume, which may contribute to the lateralisation of ischaemic stroke in the cerebral hemispheres.

Comprehensive Lipid Profiling Recapitulates Enhanced Lipolysis and Fatty Acid Metabolism in Intimal Foamy Macrophages From Murine Atherosclerotic Aorta

Lipid accumulation in macrophages is a prominent phenomenon observed in atherosclerosis. Previously, intimal foamy macrophages (FM) showed decreased inflammatory gene expression compared to intimal non-foamy macrophages (NFM). Since reprogramming of lipid metabolism in macrophages affects immunological functions, lipid profiling of intimal macrophages appears to be important for understanding the phenotypic changes of macrophages in atherosclerotic lesions. While lipidomic analysis has been performed in atherosclerotic aortic tissues and cultured macrophages, direct lipid profiling has not been performed in primary aortic macrophages from atherosclerotic aortas. We utilized nanoflow ultrahigh-performance liquid chromatography-tandem mass spectrometry to provide comprehensive lipid profiles of intimal non-foamy and foamy macrophages and adventitial macrophages from Ldlr-/- mouse aortas. We also analyzed the gene expression of each macrophage type related to lipid metabolism. FM showed increased levels of fatty acids, cholesterol esters, phosphatidylcholine, lysophosphatidylcholine, phosphatidylinositol, and sphingomyelin. However, phosphatidylethanolamine, phosphatidic acid, and ceramide levels were decreased in FM compared to those in NFM. Interestingly, FM showed decreased triacylglycerol (TG) levels. Expressions of lipolysis-related genes including Pnpla2 and Lpl were markedly increased but expressions of Lpin2 and Dgat1 related to TG synthesis were decreased in FM. Analysis of transcriptome and lipidome data revealed differences in the regulation of each lipid metabolic pathway in aortic macrophages. These comprehensive lipidomic data could clarify the phenotypes of macrophages in the atherosclerotic aorta.

Endothelial PHACTR1 Promotes Endothelial Activation and Atherosclerosis by Repressing PPARγ Activity Under Disturbed Flow in Mice

BACKGROUND

Numerous genome-wide association studies revealed that SNPs (single nucleotide polymorphisms) at the PHACTR1 (phosphatase and actin regulator 1) locus strongly correlate with coronary artery disease. However, the biological function of PHACTR1 remains poorly understood. Here, we identified the proatherosclerotic effect of endothelial PHACTR1, contrary to macrophage PHACTR1.

METHODS

We generated global (Phactr1-/-) and endothelial cell (EC)-specific (Phactr1ECKO) Phactr1 KO (knockout) mice and crossed these mice with apolipoprotein E-deficient (Apoe-/-) mice. Atherosclerosis was induced by feeding the high-fat/high-cholesterol diet for 12 weeks or partially ligating carotid arteries combined with a 2-week high-fat/high-cholesterol diet. PHACTR1 localization was identified by immunostaining of overexpressed PHACTR1 in human umbilical vein ECs exposed to different types of flow. The molecular function of endothelial PHACTR1 was explored by RNA sequencing using EC-enriched mRNA from global or EC-specific Phactr1 KO mice. Endothelial activation was evaluated in human umbilical vein ECs transfected with siRNA targeting PHACTR1 and in Phactr1ECKO mice after partial carotid ligation.

RESULTS

Global or EC-specific Phactr1 deficiency significantly inhibited atherosclerosis in regions of disturbed flow. PHACTR1 was enriched in ECs and located in the nucleus of disturbed flow areas but shuttled to cytoplasm under laminar flow in vitro. RNA sequencing showed that endothelial Phactr1 depletion affected vascular function, and PPARγ (peroxisome proliferator-activated receptor gamma) was the top transcription factor regulating differentially expressed genes. PHACTR1 functioned as a PPARγ transcriptional corepressor by binding to PPARγ through the corepressor motifs. PPARγ activation protects against atherosclerosis by inhibiting endothelial activation. Consistently, PHACTR1 deficiency remarkably reduced endothelial activation induced by disturbed flow in vivo and in vitro. PPARγ antagonist GW9662 abolished the protective effects of Phactr1 KO on EC activation and atherosclerosis in vivo.

CONCLUSIONS

Our results identified endothelial PHACTR1 as a novel PPARγ corepressor to promote atherosclerosis in disturbed flow regions. Endothelial PHACTR1 is a potential therapeutic target for atherosclerosis treatment.

Heterozygosity for ADP-ribosylation factor 6 suppresses the burden and severity of atherosclerosis

Atherosclerosis is the root cause of major cardiovascular diseases (CVD) such as myocardial infarction and stroke. ADP-ribosylation factor 6 (Arf6) is a ubiquitously expressed GTPase known to be involved in inflammation, vascular permeability and is sensitive to changes in shear stress. Here, using atheroprone, ApoE-/- mice, with a single allele deletion of Arf6 (HET) or wildtype Arf6 (WT), we demonstrate that reduction in Arf6 attenuates atherosclerotic plaque burden and severity. We found that plaque burden in the descending aorta was lower in HET compared to WT mice (p˂0.001) after the consumption of an atherogenic Paigen diet for 5 weeks. Likewise, luminal occlusion, necrotic core size, plaque grade, elastic lamina breaks, and matrix deposition were lower in the aortic root atheromas of HET compared to WT mice (all p≤0.05). We also induced advanced human-like complex atherosclerotic plaque in the left carotid artery using partial carotid ligation surgery and found that atheroma area, plaque grade, intimal necrosis, intraplaque hemorrhage, thrombosis, and calcification were lower in HET compared to WT mice (all p≤0.04). Our findings suggest that the atheroprotection afforded by Arf6 heterozygosity may result from reduced immune cell migration (all p≤0.005) as well as endothelial and vascular smooth muscle cell proliferation (both p≤0.001) but independent of changes in circulating lipids (all p≥0.40). These findings demonstrate a critical role for Arf6 in the development and severity of atherosclerosis and suggest that Arf6 inhibition can be explored as a novel therapeutic strategy for the treatment of atherosclerotic CVD.

Lipoprotein(a) is associated with a larger systemic burden of arterial calcification

AIMS

Lipoprotein(a) [Lp(a)] is a genetically determined risk factor for cardiovascular disease. However, population-based evidence on the link between Lp(a) and subclinical arteriosclerosis is lacking. We assessed associations of Lp(a) concentrations with arteriosclerosis in multiple arteries.

METHODS AND RESULTS

From the population-based Rotterdam study, 2354 participants (mean age: 69.5 years, 52.3% women) underwent non-contrast computed tomography to assess arterial calcification as a hallmark of arteriosclerosis. We quantified the volume of coronary artery calcification (CAC), aortic arch calcification (AAC), extracranial (ECAC), and intracranial carotid artery calcification (ICAC). All participants underwent blood sampling, from which plasma Lp(a) concentrations were derived. The association of plasma Lp(a) levels was assessed with calcification volumes and with severe calcification (upper quartile of calcification volume) using sex-stratified multivariable linear and logistic regression models. Higher Lp(a) levels were associated with larger ln-transformed volumes of CAC [fully adjusted beta 95% confidence interval (CI) per 1 standard deviation (SD) in women: 0.09, 95% CI 0.04-0.14, men: 0.09, 95% CI 0.03-0.14], AAC (women: 0.06, 95% CI 0.01-0.11, men: 0.09, 95% CI 0.03-0.14), ECAC (women: 0.07, 95% CI 0.02-0.13, men: 0.08, 95% CI 0.03-0.14), and ICAC (women: 0.09, 95% CI 0.03-0.14, men: 0.05, 95% CI -0.02 to 0.11]. In the highest Lp(a) percentile, severe ICAC was most prevalent in women [fully adjusted odds ratio (OR) 2.41, 95% CI 1.25-4.63] and severe AAC in men (fully adjusted OR 3.29, 95% CI 1.67-6.49).

CONCLUSION

Higher Lp(a) was consistently associated with a larger calcification burden in all major arteries. The findings of this study indicate that Lp(a) is a systemic risk factor for arteriosclerosis and thus potentially an effective target for treatment. Lp(a)-reducing therapies may reduce the burden from arteriosclerotic events throughout the arterial system.

TRANSLATIONAL PERSPECTIVE

In 2354 participants from the Rotterdam study, we assessed the link between Lp(a) concentrations and arterial calcifications, as proxy for arteriosclerosis, in major arteries. We found that higher Lp(a) levels were consistently associated with larger volumes of calcification in the coronary arteries, aortic arch, extracranial carotid arteries, and intracranial carotid arteries. The findings of our study indicate that Lp(a) is a systemic risk factor for arteriosclerosis, suggesting that the systemic burden of arteriosclerosis throughout the arterial system could be reduced by targeting Lp(a).

Focal dissection and rupture of left atherosclerotic subclavian artery: a rare cause of haemothorax

We report a rare case of a focally dissected and ruptured atherosclerotic left subclavian artery leading to haemothorax. A man in his 50 s who suffered from hypertension and gout was found dead in bed unexpectedly. Postmortem examination showed a focally dissected and ruptured atherosclerotic left subclavian artery with relatively disease-free aorta and major branches. Although theoretically possible, focal atherosclerosis of left subclavian artery compounded by hypertension causing focal dissection and rupture is not previously reported in literature.

Re-Visiting Antioxidant Therapy in Murine Advanced Atherosclerosis with Brussels Chicory, a Typical Vegetable in Mediterranean Diets

Brussels chicory, a typical vegetable in Mediterranean diets, has been recently reported to stabilize advanced atherosclerotic plaques in the brachiocephalic artery of apoE-deficient (Apoe-/-) mice. Herein, we investigated whether Brussels chicory can stabilize advanced plaques in the aorta via improving oxidative stress. Thirty week old Apoe-/- mice were fed the AIN-93G diet or supplemented with 0.5% freeze-dried Brussels chicory for twenty weeks. Aortic plaque size and stability, aortic relaxation, monocyte adhesion to aortic endothelium, free radicals, and enzymatic and non-enzymatic factors involved in free radical production and elimination in aorta and serum were measured. Brussels chicory consumption did not alter aortic plaque size, however, it stabilized aortic plaques, promoted aortic relaxation, and also inhibited monocyte adhesion to aortic endothelium. Moreover, this administration reduced oxidized LDL (ox-LDL) and 4-hydroxynonenal (4-HNE) content in aortic plaques, associated with inhibited aortic NADPH oxidase (NOX) and uncoupled endothelial nitric oxide synthase (eNOS)-mediated free radical production. However, Brussels chicory consumption did not appreciably alter aortic and serum superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities, aortic glutathione (GSH), as well as serum non-enzymatic antioxidants, such as bilirubin, uric acid, and GSH. Collectively, improved oxidative stress might contribute to the atheroprotective effect of Brussels chicory, supporting the prospect of the antioxidant therapy in advanced atherosclerosis progression.

The Involvement of Cx43 in JNK1/2-Mediated Endothelial Mechanotransduction and Human Plaque Progression

Atherosclerotic lesions preferentially develop at bifurcations, characterized by non-uniform shear stress (SS). The aim of this study was to investigate SS-induced endothelial activation, focusing on stress-regulated mitogen-activated protein kinases (MAPK) and downstream signaling, and its relation to gap junction proteins, Connexins (Cxs). Human umbilical vein endothelial cells were exposed to flow ("mechanical stimulation") and stimulated with TNF-α ("inflammatory stimulation"). Phosphorylated levels of MAPKs (c-Jun N-terminal kinase (JNK1/2), extracellular signal-regulated kinase (ERK), and p38 kinase (p38K)) were quantified by flow cytometry, showing the activation of JNK1/2 and ERK. THP-1 cell adhesion under non-uniform SS was suppressed by the inhibition of JNK1/2, not of ERK. Immunofluorescence staining and quantitative real-time PCR demonstrated an induction of c-Jun and c-Fos and of Cx43 in endothelial cells by non-uniform SS, and the latter was abolished by JNK1/2 inhibition. Furthermore, plaque inflammation was analyzed in human carotid plaques (n = 40) using immunohistochemistry and quanti-gene RNA-assays, revealing elevated Cx43⁺ cell counts in vulnerable compared to stable plaques. Cx43⁺ cell burden in the plaque shoulder correlated with intraplaque neovascularization and lipid core size, while an inverse correlation was observed with fibrous cap thickness. Our results constitute the first report that JNK1/2 mediates Cx43 mechanoinduction in endothelial cells by atheroprone shear stress and that Cx43 is expressed in human carotid plaques. The correlation of Cx43⁺ cell counts with markers of plaque vulnerability implies its contribution to plaque progression.

Inhibition of Trimethylamine N-Oxide Attenuates Neointimal Formation Through Reduction of Inflammasome and Oxidative Stress in a Mouse Model of Carotid Artery Ligation

Aims: Trimethylamine-N-oxide (TMAO) is a metabolite generated from dietary choline, betaine, and l-carnitine, after their oxidization in the liver. TMAO has been identified as a novel independent risk factor for atherosclerosis through the induction of vascular inflammation. However, the effect of TMAO on neointimal formation in response to vascular injury remains unclear. Results: This study was conducted using a murine model of acutely disturbed flow-induced atherosclerosis induced by partial carotid artery ligation. 3,3-Dimethyl-1-butanol (DMB) was used to reduce TMAO concentrations. Wild-type mice were divided into four groups [regular diet, high-TMAO diet, high-choline diet, and high-choline diet+DMB] to investigate the effects of TMAO elevation and its inhibition by DMB. Mice fed high-TMAO and high-choline diets had significantly enhanced neointimal hyperplasia and advanced plaques, elevated arterial elastin fragmentation, increased macrophage infiltration and inflammatory cytokine secretion, and enhanced activation of nuclear factor (NF)-κB, the NLRP3 inflammasome, and endoplasmic reticulum (ER) stress relative to the control group. Mice fed high-choline diets with DMB treatment exhibited attenuated flow-induced atherosclerosis, inflammasome expression, ER stress, and reactive oxygen species expression. Human aortic smooth muscle cells (HASMCs) were used to investigate the mechanism of TMAO-induced injury. The HASMCs were treated with TMAO with or without an ER stress inhibitor to determine whether inhibition of ER stress modulates the TMAO-induced inflammatory response. Innovation: This study demonstrates that TMAO regulates vascular remodeling via ER stress. Conclusion: Our findings demonstrate that TMAO elevation promotes disturbed flow-induced atherosclerosis and that DMB administration mitigates vascular remodeling, suggesting a rationale for a TMAO-targeted strategy for the treatment of atherosclerosis. Antioxid. Redox Signal. 38, 215-233.

Simulation of LDL permeation into multilayer wall of a coronary bifurcation using WSS-dependent model: effects of hemorheology

Atherosclerosis, due to the permeation of low-density lipoprotein (LDL) particles into the arterial wall, is one of the most common and deadly diseases in today's world. Due to its importance, numerous studies have been conducted on the factors affecting this disease. In this study, using numerical simulation, the effects of Wall Shear Stress (WSS), non-Newtonian behavior of blood, different values of hematocrit and blood pressure on LDL permeation into the arterial wall layers are investigated in a 4-layer wall model of a coronary bifurcation. To obtain the velocity and concentration fields in the fluid domain, the Navier-Stokes, Brinkman, and mass transfer equations are numerically solved in the lumen and wall layers. Results show that it is important to consider the effects of WSS on transport properties of endothelium layer in bifurcations and this leads to completely different concentration profiles compared to the constant properties model. Our computations show that a giant accumulation of LDL in the intima layer of the outer wall of the left anterior descending artery, especially in low WSS regions, may lead to atherosclerosis. It is also, necessary to consider the non-Newtonian behavior of blood in bifurcations due to its direct effect on WSS. A pressure-induced increase in the half-width of leaky junctions may be responsible for the higher risk of atherosclerosis in hypertension. In addition, it is shown that the dominant mechanism in LDL permeation into the wall is convection, and also, hypertension increases the effect of mass transfer by convection mechanism more than the diffusion mechanism. Furthermore, our results are consistent with various clinical studies.

Translating atherosclerosis research from bench to bedside: navigating the barriers for effective preclinical drug discovery

Cardiovascular disease (CVD) remains the leading cause of death worldwide. An ongoing challenge remains the development of novel pharmacotherapies to treat CVD, particularly atherosclerosis. Effective mechanism-informed development and translation of new drugs requires a deep understanding of the known and currently unknown biological mechanisms underpinning atherosclerosis, accompanied by optimization of traditional drug discovery approaches. Current animal models do not precisely recapitulate the pathobiology underpinning human CVD. Accordingly, a fundamental limitation in early-stage drug discovery has been the lack of consensus regarding an appropriate experimental in vivo model that can mimic human atherosclerosis. However, when coupled with a clear understanding of the specific advantages and limitations of the model employed, preclinical animal models remain a crucial component for evaluating pharmacological interventions. Within this perspective, we will provide an overview of the mechanisms and modalities of atherosclerotic drugs, including those in the preclinical and early clinical development stage. Additionally, we highlight recent preclinical models that have improved our understanding of atherosclerosis and associated clinical consequences and propose model adaptations to facilitate the development of new and effective treatments.

Long non-coding RNAs at the crossroad of vascular smooth muscle cell phenotypic modulation in atherosclerosis and neointimal formation

Despite extraordinary advances in the comprehension of the pathophysiology of atherosclerosis and the employment of very effective treatments, cardiovascular diseases are still a major cause of mortality and represent a large share of health expenditure worldwide. Atherosclerosis is a disease affecting the medium and large arteries, which consists of a progressive accumulation of fatty substances, cellular waste products and fibrous elements, which culminates in the buildup of a plaque obstructing the blood flow. Endothelial dysfunction represents an early pathological event, favoring immune cells recruitment and triggering local inflammation. The release of inflammatory cytokines and other signaling molecules stimulates phenotypic modifications in the underlying vascular smooth muscle cells, which, in physiological conditions, are responsible for the maintenance of vessels architecture while regulating vascular tone. Vascular smooth muscle cells are highly plastic and may respond to disease stimuli by de-differentiating and losing their contractility, while increasing their synthetic, proliferative, and migratory capacity. This phenotypic switching is considered a pathological hallmark of atherogenesis and is ruled by the activation of selective gene programs. The advent of genomics and the improvement of sequencing technologies deepened our knowledge of the complex gene expression regulatory networks mediated by non-coding RNAs, and favored the rise of innovative therapeutic approaches targeting the non-coding transcriptome. In the context of atherosclerosis, long non-coding RNAs have received increasing attention as potential translational targets, due to their contribution to the molecular dynamics modulating the expression of vascular smooth muscle cells contractile/synthetic gene programs. In this review, we will focus on the most well-characterized long non-coding RNAs contributing to atherosclerosis by controlling expression of the contractile apparatus and genes activated in perturbed vascular smooth muscle cells.

Analysis of atherosclerotic plaque distribution in the carotid artery

BACKGROUND

The present study was designed to investigate the hypothesis that the outer wall at the carotid bifurcation is the most common area of atherosclerotic plaque deposition due to the low shear stress.

HYPOTHESIS

We hypothesized that the most common site of arteriosclerosis in carotid arteries is different in the early and late stages.

METHODS

This is an observational study of patients with <50% stenosis of the common and internal carotid arteries (ICAs) identified by Duplex ultrasound in our health promotion center. Plaque location was categorized as a quarter of the cross-section in the distal common carotid artery (CCA) and proximal ICA. Carotid plaque score (CPS) was calculated by the addition of one point for each detected section. The sum of CPSs was calculated for each section.

RESULTS

Among 3996 Duplex scans of carotid arteries in 999 patients between June 2020 and October 2020, a total of 569 patients (73.6% male; mean age, 68.4± 9.1 years; 652 CCAs and 567 ICAs) were included. Total CPS was high in the anterior and posterior sections. The distribution in the ICA was: 308 (31.0%) anterior, 90 (9.0%) medial, 373 (37.5%) posterior, and 224 (22.5%) lateral section. The distribution in the CCA was 385 (32.6%) anterior, 103 (8.7%) medial, 528 (44.7%) posterior, and 165 (14.0%) lateral section. The axial distribution of posterior and lateral sections was significantly different according to the directional flow (p < .001).

CONCLUSIONS

Anterior and posterior sections of the CCA and ICA were atherosclerotic plaque-prone sites. This result is different from the tendency of atherogenesis to affect the lateral section having low shear stress at the carotid bifurcation.

Aging results in DNA damage and telomere dysfunction that is greater in endothelial versus vascular smooth muscle cells and is exacerbated in atheroprone regions

Aging increases the risk of atherosclerotic cardiovascular disease which is associated with arterial senescence; however, the mechanisms responsible for the development of cellular senescence in endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) remain elusive. Here, we study the effect of aging on arterial DNA damage and telomere dysfunction. Aging resulted in greater DNA damage in ECs than VSMCs. Further, telomere dysfunction-associated DNA damage foci (TAF: DNA damage signaling at telomeres) were elevated with aging in ECs but not VMSCs. Telomere length was modestly reduced in ECs with aging and not sufficient to induce telomere dysfunction. DNA damage and telomere dysfunction were greatest in atheroprone regions (aortic minor arch) versus non-atheroprone regions (thoracic aorta). Collectively, these data demonstrate that aging results in DNA damage and telomere dysfunction that is greater in ECs than VSMCs and elevated in atheroprone aortic regions.

Single-Cell RNA-Seq Reveals a Population of Smooth Muscle Cells Responsible for Atherogenesis

Understanding the regional propensity differences of atherosclerosis (AS) development is hindered by the lack of animal models suitable for the study of the disease process. In this paper, we used 3S-ASCVD dogs, an ideal large animal human-like models for AS, to interrogate the heterogeneity of AS-prone and AS-resistant arteries; and at the single-cell level, identify the dominant cells involved in AS development. Here we present data from 3S-ASCVD dogs which reliably mimic human AS pathophysiology, predilection for lesion sites, and endpoint events. Our analysis combined bulk RNA-seq with single-cell RNA-seq to depict the transcriptomic profiles and cellular atlas of AS-prone and AS-resistant arteries in 3S-ASCVD dogs. Our results revealed the integral role of smooth muscle cells (SMCs) in regional propensity for AS. Notably, TNC+ SMCs were major contributors to AS development in 3S-ASCVD dogs, indicating enhanced extracellular matrix remodeling and transition to myofibroblasts during the AS process. Moreover, TNC+ SMCs were also present in human AS-prone carotid plaques, suggesting a potential origin of myofibroblasts and supporting the relevance of our findings. Our study provides a promising large animal model for pre-clinical studies of ASCVD and add novel insights surrounding the regional propensity of AS development in humans, which may lead to interventions that delay or prevent lesion progression and adverse clinical events.

Circulating Notch1 in response to altered vascular wall shear stress in adults

NEW FINDINGS

What is the central question of this study? Is the plasma concentration of Notch1 extracellular domain altered in response to decreased and increased vascular wall shear stress in the forearm in humans? What is the main finding and its importance? Notch1 extracellular domain is increased with acute increases in antegrade shear rate but does not change with 20 min of decreased shear rate caused by distal forearm occlusion. A novel and integral endothelial mechanosensor in humans that can help explain vascular endothelial adjustments in response to increases in antegrade shear stress was characterized.

ABSTRACT

Notch1 has been proposed as a novel endothelial mechanosensor that is central for signalling adjustments in response to changes in vascular wall shear stress. However, there remains no controlled in vivo study in humans. Accordingly, we sought to address the question of whether plasma concentrations of Notch1 extracellular domain (ECD) is altered in response to transient changes in vascular wall shear stress. In 10 young healthy adults (6M/4F), alterations in shear stress were induced by supra-systolic cuff inflation around the wrist. The opposite arm was treated as a time control with no wrist cuff inflation. Plasma was collected from an antecubital vein of both arms at baseline, 20 min of wrist cuff inflation (low shear), as well as 1-2 min (high shear) and 15 min following (recovery) wrist cuff release. The Notch1 ECD was quantified using a commercially available ELISA. Duplex ultrasound was used to confirm alterations in shear stress. In the experimental arm, concentrations of Notch1 ECD remained statistically similar to baseline at all time points except for immediately following cuff release where it was elevated by ∼50% (P = 0.033), coinciding with the condition of high antegrade shear rate. Concentrations of Notch1 ECD remained unchanged in the control arm through all time points. These data indicate that Notch1 is a viable biomarker for quantifying mechanotransduction in response to increased shear stress in humans, and it may underlie the vascular adaptations or mal-adaptations associated with conditions that impact antegrade shear.

Analysis of Gene Single Nucleotide Polymorphisms in COVID-19 Disease Highlighting the Susceptibility and the Severity towards the Infection

Many factors may influence the risk of being infected by SARS-CoV-2, the coronavirus responsible for coronavirus disease 2019 (COVID-19). Exposure to the virus cannot explain the variety of an individual's responses to the virus and the high differences of effect that the virus may cause to some. While a person's preexisting condition and their immune defenses have been confirmed to play a major role in the disease progression, there is still much to learn about hosts' genetic makeup towards COVID-19 susceptibility and risk. The host genetic makeup may have direct influence on the grade of predisposition and outcomes of COVID-19. In this study, we aimed to investigate the presence of relevant genetic single nucleotide polymorphisms (SNPs), the peripheral blood level of IL6, vitamin D and arterial blood gas (ABG) markers (pH, oxygen-SpO₂ and carbon dioxide-SpCO₂) on two groups, COVID-19 (n = 41, study), and the healthy (n = 43, control). We analyzed cytokine and interleukin genes in charge of both pro-inflammatory and immune-modulating responses and those genes that are considered involved in the COVID-19 progression and complications. Thus, we selected major genes, such as IL1β, IL1RN (IL-1 β and α receptor) IL6, IL6R (IL-6 receptor), IL10, IFNγ (interferon gamma), TNFα (tumor necrosis factor alpha), ACE2 (angiotensin converting enzyme), SERPINA3 (Alpha-1-Antiproteinase, Antitrypsin member of Serpin 3 family), VDR (vitamin D receptor Tak1, Bsm1 and Fok1), and CRP (c-reactive protein). Though more research is needed, these findings may give a better representation of virus pleiotropic activity and its relation to the immune system.

Perivascular mechanical environment: A narrative review of the role of externally applied mechanical force in the pathogenesis of atherosclerosis

Atherosclerosis is promoted by systemic factors, such as dyslipidemia, hypertension, diabetes, and smoking, which cause atherosclerosis in blood vessels throughout the body. However, atherosclerotic lesions are characterized by their frequent occurrence in specific vessels and sites. Blood vessels are exposed to various mechanical forces related to blood pressure and flow. Although shear stress promotes the initiation and progression of atherosclerotic lesions, the pathogenesis of site specificity of atherosclerosis is not sufficiently explained by shear stress. We propose the concept of a perivascular mechanical environment (PVME). Compelling evidence suggests that site specificity in atherosclerotic lesions depends on a distinct local PVME. Atheroprone arteries, such as the coronary artery, are markedly affected by externally applied mechanical force (EMF), whereas atheroprotective arteries, such as the internal thoracic artery, are less affected. Recent studies have shown that the coronary artery is affected by cardiac muscle contraction, the carotid artery by the hyoid bone and the thyroid cartilage, and the abdominal aorta and lower extremity arteries by musculoskeletal motion. We speculate that the thoracic cage protects the internal thoracic artery from EMF owing to a favorable PVME. Furthermore, evidence suggests that plaque eccentricity is provided by EMF; plaques are frequently observed on an external force-applied side. In each vascular tree, site-specific characteristics of the PVME differ substantially, inducing individual atherogenicity. From the perspective of the mechanical environment, hemodynamic stress occurs in an inside-out manner, whereas EMF occurs in an outside-in manner. These inward and outward forces apply mechanical load individually, but interact synergistically. The concept of a PVME is a novel pathogenesis of atherosclerosis and also might be a pathogenesis of other arterial diseases.

Interleukin 37; a possible marker of arterial stiffness in Behçet's disease

BACKGROUND

Interleukin 37 (IL-37) is an anti-inflammatory cytokine previously studied in Behçet's disease (BD) and atherosclerosis. However, little is known about its relation to macro and microcirculations in BD. Previous studies relied mainly on common carotid artery (CCA) intima-media thickness (IMT) and ankle brachial index (ABI) to study atherosclerosis in BD with conflicting results. This study evaluated flow parameters of CCA, ABI and nailfold videocapillaroscopy in relation to serum IL-37 in BD.

METHODS

Forty BD patients and 30 healthy controls were included. IMT, peak-systolic, end-diastolic velocities, resistivity index of CCA and ABI were measured by duplex ultrasound. Capillary loop, length, diameter and morphology were recorded by nailfold videocapillaroscopy. Serum IL-37 levels were measured using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Compared to controls, patients had higher mean CCA IMT (p < 0.0001), resistivity index (p < 0.001) and peak-systolic velocity (p=0.09) and lower mean CCA end-diastolic velocity (p=0.002), capillary loop, length, arterial, venous limbs diameter and serum IL-37 (p < 0.001). Patients with ABI ≥ 1.4 "indicating stiff arteries" had higher serum IL-37 (p < 0.05 on left, p>0.05 right sides). Serum IL-37 correlated negatively with left CCA end-diastolic velocity "denoting atherosclerosis" and positively with left posterior tibial artery ABI and CRP (p < 0.03) "denoting inflammation". Multiple regression analysis showed only association with left CCA end-diastolic velocity.

CONCLUSIONS

IL-37 may be related to arterial stiffness in BD and could be used as a possible marker of arteriosclerosis in the disease for further investigations. Changes of CCA peak-systolic, end-diastolic velocities, resistivity index and IMT refer to increased atherosclerosis in larger elastic arteries. In smaller muscular "crural" arteries, vasculitis with possible medial disease may be more evident.

Defective efferocytosis of vascular cells in heart disease

The efficient phagocytic clearance of dying cells and apoptotic cells is one of the processes that is essential for the maintenance of physiologic tissue function and homeostasis, which is termed "efferocytosis." Under normal conditions, "find me" and "eat me" signals are released by apoptotic cells to stimulate the engulfment and efferocytosis of apoptotic cells. In contrast, abnormal efferocytosis is related to chronic and non-resolving inflammatory diseases such as atherosclerosis. In the initial steps of atherosclerotic lesion development, monocyte-derived macrophages display efficient efferocytosis that restricts plaque progression; however, this capacity is reduced in more advanced lesions. Macrophage reprogramming as a result of the accumulation of apoptotic cells and augmented inflammation accounts for this diminishment of efferocytosis. Furthermore, defective efferocytosis plays an important role in necrotic core formation, which triggers plaque rupture and acute thrombotic cardiovascular events. Recent publications have focused on the essential role of macrophage efferocytosis in cardiac pathophysiology and have pointed toward new therapeutic strategies to modulate macrophage efferocytosis for cardiac tissue repair. In this review, we discuss the molecular and cellular mechanisms that regulate efferocytosis in vascular cells, including macrophages and other phagocytic cells and detail how efferocytosis-related molecules contribute to the maintenance of vascular hemostasis and how defective efferocytosis leads to the formation and progression of atherosclerotic plaques.

Chronic Atherothrombosis in a Sub-Massive Infrarenal Abdominal Aortic Aneurysm in a 91-Year-Old White Male Donor

Screening for abdominal aortic aneurysms became the standard of care in 2005, yet screening procedures continue to be underutilized. While improvements in mortality rates have been noted over the past 15 years, continued patient mortality from ruptured abdominal aortic aneurysms suggests a need for further research, regarding the effectiveness of the current screening process. Abdominal aortic aneurysms can progress silently, and the risk of rupture increases significantly with increase in diameter. We report a large, untreated infrarenal abdominal aortic aneurysm of 17 cm in length and 8 cm in diameter, showing the chronic atherothrombosis discovered in a 91 year-old white male cadaveric donor. A literature review was conducted to elucidate current understanding of the pathology, risk factors, screening recommendations, and treatment options available for abdominal aortic aneurysms.