Early human atherosclerosis: accumulation of lipid and proteoglycans in intimal thickenings followed by macrophage infiltration

Apolipoprotein B-containing lipoproteins in atherogenesis

Apolipoprotein B (apoB) is the main structural protein of LDLs, triglyceride-rich lipoproteins and lipoprotein(a), and is crucial for their formation, metabolism and atherogenic properties. In this Review, we present insights into the role of apoB-containing lipoproteins in atherogenesis, with an emphasis on the mechanisms leading to plaque initiation and growth. LDL, the most abundant cholesterol-rich lipoprotein in plasma, is causally linked to atherosclerosis. LDL enters the artery wall by transcytosis and, in vulnerable regions, is retained in the subendothelial space by binding to proteoglycans via specific sites on apoB. A maladaptive response ensues. This response involves modification of LDL particles, which promotes LDL retention and the release of bioactive lipid products that trigger inflammatory responses in vascular cells, as well as adaptive immune responses. Resident and recruited macrophages take up modified LDL, leading to foam cell formation and ultimately cell death due to inadequate cellular lipid handling. Accumulation of dead cells and cholesterol crystallization are hallmarks of the necrotic core of atherosclerotic plaques. Other apoB-containing lipoproteins, although less abundant, have substantially greater atherogenicity per particle than LDL. These lipoproteins probably contribute to atherogenesis in a similar way to LDL but might also induce additional pathogenic mechanisms. Several targets for intervention to reduce the rate of atherosclerotic lesion initiation and progression have now been identified, including lowering plasma lipoprotein levels and modulating the maladaptive responses in the artery wall.

Combination therapy and drug co-delivery systems for atherosclerosis

Atherosclerosis is a chronic inflammatory disease characterized by the accumulation of plaque within the arteries. Despite advances in therapeutic strategies including anti-inflammatory, antioxidant, and lipid metabolism modulation treatments over the past two decades, the treatment of atherosclerosis remains challenging, as arterial damage is the result of interconnected pathological factors. Therefore, current monotherapies often fail to address the complex nature of this disease, leading to insufficient therapeutic outcomes. This review addressed this paucity of effective treatment options by comprehensively exploring the potential for combination therapies and advanced drug co-delivery systems for the treatment of atherosclerosis. We investigated the pathological features of and risk factors for atherosclerosis, underscoring the importance of drug combination therapies for the treatment of atherosclerotic diseases. We discuss herein mathematical models for quantifying the efficacy of the combination therapies and provide a systematic summary of drug combinations for the treatment of atherosclerosis. We also provide a detailed review of the latest advances in nanoparticle-based drug co-delivery systems for the treatment of atherosclerosis, focusing on the design of carriers with high biocompatibility and efficacy. By exploring the possibilities and challenges inherent to this approach, we aim to highlight cutting-edge technologies that can foster the development of innovative strategies, optimize drug co-administration, improve treatment outcomes, and reduce the burden of atherosclerosis-related morbidity and mortality on the healthcare system.

Association between hemoglobin, albumin, lymphocyte, and platelet scores and all-cause and cardiovascular mortality among adults with atherosclerotic cardiovascular disease in the United States: An analysis of NHANES

Atherosclerotic cardiovascular disease (ASCVD) remains the foremost cause of mortality in the United States. The hemoglobin, albumin, lymphocyte, and platelet (HALP) score, a straightforward and economical indicator, combines inflammatory and nutritional status. However, its association with ASCVD incidence and long-term mortality is uncertain. We conducted a cross-sectional study using US National Health and Nutrition Examination Survey data from 1999 to 2020, with mortality data collected until December 31, 2019, via the National Death Index. Weighted multivariable logistic regression was employed to assess the association between HALP scores and ASCVD prevalence. Kaplan-Meier analyses and weighted multivariate-adjusted Cox analyses were utilized to examine the relationship between HALP scores and all-cause and cardiovascular disease (CVD) mortality among patients with ASCVD. Restricted cubic spline curve (RCS) analysis was used to identify nonlinear relationships, and multisubgroup and sensitivity analyses were conducted to ensure the robustness of the results. This cohort study comprised 41,147 participants, including 4047 with ASCVD (prevalence: 7.7%). Over a median follow-up of 85 (49, 131) months, 1726 deaths occurred among patients with ASCVD, with 575 attributed to CVD. Multivariable-adjusted modeling showed no association between HALP score and ASCVD incidence. However, multivariable-adjusted Cox regression and RCS analyses revealed a nonlinear relationship between HALP scores and all-cause mortality and CVD mortality in patients with ASCVD (all P for nonlinearity < 0.001). Higher HALP scores were significantly associated with reduced all-cause and CVD mortality in patients with ASCVD (all P for trend < 0.05). Our results indicate a significant nonlinear association between HALP scores and all-cause as well as cardiovascular mortality in patients with ASCVD. Higher HALP scores are linked to decreased all-cause mortality and CVD mortality.

Extracellular matrix in vascular homeostasis and disease

The extracellular matrix is an essential component and constitutes a dynamic microenvironment of the vessel wall with an indispensable role in vascular homeostasis and disease. From early development through to ageing, the vascular extracellular matrix undergoes various biochemical and biomechanical alterations in response to diverse environmental cues and exerts precise regulatory control over vessel remodelling. Advances in novel technologies that enable the comprehensive evaluation of extracellular matrix components and cell-matrix interactions have led to the emergence of therapeutic strategies that specifically target this fine-tuned network. In this Review, we explore various aspects of extracellular matrix biology in vascular development, disorders and ageing, emphasizing the effect of the extracellular matrix on disease initiation and progression. Additionally, we provide an overview of the potential therapeutic implications of targeting the extracellular matrix microenvironment in vascular diseases.

Coronary Artery Spasm: From Physiopathology to Diagnosis

Coronary artery spasm (CAS) is a reversible vasoconstriction of normal or atherosclerotic epicardial coronary arteries with a subsequent reduction in myocardial blood flow, leading to myocardial ischemia, myocardial infarction, severe arrhythmias, or even sudden death. It is an entity that should be recognized based on a particular clinical presentation. Numerous differences exist between CAS and obstructive coronary disease in terms of mechanisms, risk factors, and therapeutic solutions. The gold standard for CAS diagnosis is represented by transitory and reversible occlusion of the coronary arteries at spasm provocation test, which consists of an intracoronary administration of Ach, ergonovine, or methylergonovine during angiography. The pathophysiology of CAS is not fully understood. However, the core of CAS is represented by vascular smooth muscle cell contraction, with a circadian pattern. The initiating event of this contraction may be represented by endothelial dysfunction, inflammation, or autonomic nervous system unbalance. Our study explores the intricate balance of these factors and their clinical relevance in the management of CAS.

Inflammation in atherosclerosis: a Big Idea that has underperformed so far

PURPOSE OF REVIEW

For many years, inflammation has been a major concept in basic research on atherosclerosis and in the development of potential diagnostic tools and treatments. The purpose of this review is to assess the performance of this concept with an emphasis on recent clinical trials. In addition, contemporary literature may help identify new therapeutic targets, particularly in the context of the treatment of early, rather than end-stage, arterial disease.

RECENT FINDINGS

Newly reported clinical trials cast doubt on the efficacy of colchicine, the sole anti-inflammatory agent currently approved for use in patients with atherosclerotic cardiovascular disease (ASCVD). New analyses also challenge the hypothesis that residual ASCVD event risk after optimal management of lipids, blood pressure, and smoking arises primarily from residual inflammatory risk. Current clinical practice to initiate interventions so late in the course of atherosclerotic arterial disease may be a better explanation. Lipid-lowering therapy in early atherosclerosis, possibly combined with novel add-on agents to specifically accelerate resolution of maladaptive inflammation, may be more fruitful than the conventional approach of testing immunosuppressive strategies in end-stage arterial disease. Also discussed is the ongoing revolution in noninvasive technologies to image the arterial wall. These technologies are changing screening, diagnosis, and treatment of atherosclerosis, including early and possibly reversable disease.

SUMMARY

The burden of proof that the Big Idea of inflammation in atherosclerosis has clinical value remains the responsibility of its advocates. This responsibility requires convincing trial data but still seems largely unmet. Unfortunately, the focus on inflammation as the source of residual ASCVD event risk has distracted us from the need to screen and treat earlier.

3D bioprinting technology for modeling vascular diseases and its application

In vitromodeling of vascular diseases provides a useful platform for drug screening and mechanistic studies, by recapitulating the essential structures and physiological characteristics of the native tissue. Bioprinting is an emerging technique that offers high-resolution 3D capabilities, which have recently been employed in the modeling of various tissues and associated diseases. Blood vessels are composed of multiple layers of distinct cell types, and experience different mechanical conditions depending on the vessel type. The intimal layer, in particular, is directly exposed to such hemodynamic conditions inducing shear stress, which in turn influence vascular physiology. 3D bioprinting techniques have addressed the structural limitations of the previous vascular models, by incorporating supporting cells such as smooth muscle cells, geometrical properties such as dilation, curvature, or branching, or mechanical stimulation such as shear stress and pulsatile pressure. This paper presents a review of the physiology of blood vessels along with the pathophysiology of the target diseases including atherosclerosis, thrombosis, aneurysms, and tumor angiogenesis. Additionally, it discusses recent advances in fabricatingin vitro3D vascular disease models utilizing bioprinting techniques, while addressing the current challenges and future perspectives for the potential clinical translation into therapeutic interventions.

An intimal-lumen model in a microfluidic device: potential platform for atherosclerosis-related studies

Atherosclerosis is a chronic inflammatory vascular disorder driven by factors such as endothelial dysfunction, hypertension, hyperlipidemia, and arterial calcification, and is considered a leading global cause of death. Existing atherosclerosis models have limitations due to the absence of an appropriate hemodynamic microenvironment in vitro and interspecies differences in vivo. Here, we develop a simple but robust microfluidic intimal-lumen model of early atherosclerosis using interconnected dual channels for studying monocyte transmigration and foam cell formation at an arterial shear rate. To the best of our knowledge, this is the first study that creates a physiologically relevant microenvironment under an arterial shear rate to modulate lipid-laden foam cells on a microfluidic platform. As a proof of concept, we use murine endothelial cells to develop a vascular lumen in one channel and collagen-embedded murine smooth muscle cells to mimic the subendothelial intimal layer in another channel. The model successfully triggers endothelial dysfunction upon TNF-α stimulation, initiating monocyte adhesion to the endothelial monolayer under the arterial shear rate. Unlike existing in vitro models, native low-density lipoprotein (LDL) is added in the culture media instead of ox-LDL to stimulate subendothelial lipid accumulation, thereby mimicking more accurate physiology. The subendothelial transmigration of adherent monocytes and subsequent foam cell formation is also achieved under flow conditions in the model. The model also investigates the inhibitory effect of aspirin in monocyte adhesion and transmigration. The model exhibits a significant dose-dependent reduction in monocyte adhesion and transmigration upon aspirin treatment, making it an excellent tool for drug testing.

Promising Adventitia in Atherosclerosis

The adventitia, the artery's most intricate layer, has received little attention. During atherosclerosis, adventitia components undergo significant changes, such as angiogenesis, lymphangiogenesis, Artery Tertiary Lymphoid Organ (ATLO) formation, axon density increase, fibroblast activation, and stem cell differentiation. The reasons behind these changes and their contribution to atherosclerosis are beginning to be understood. In this review, we summarize the adventitia components and their role in normal arteries and then discuss the changes, pathogenesis, and potential clinical application of the adventitia in atherosclerosis.

Smooth muscle-specific deletion of cellular communication network factor 2 causes severe aorta malformation and atherosclerosis

AIMS

Cellular communication network factor 2 (CCN2) is a matricellular protein implicated in fibrotic diseases, with ongoing clinical trials evaluating anti-CCN2-based therapies. By uncovering CCN2 as abundantly expressed in non-diseased artery tissue, this study aimed to investigate the hypothesis that CCN2 plays a pivotal role in maintaining smooth muscle cell (SMC) phenotype and protection against atherosclerosis.

METHODS AND RESULTS

Global- and SMC-specific Ccn2 knockout mouse models were employed to demonstrate that Ccn2 deficiency leads to SMC de-differentiation, medial thickening, and aorta elongation under normolipidaemic conditions. Inducing hyperlipidaemia in both models resulted in severe aorta malformation and a 17-fold increase in atherosclerosis formation. Lipid-rich lesions developed at sites of the vasculature typically protected from atherosclerosis development by laminar blood flow, covering 90% of aortas and extending to other vessels, including coronary arteries. Evaluation at earlier time points revealed medial lipid accumulation as a lesion-initiating event. Fluorescently labelled LDL injection followed by confocal microscopy showed increased LDL retention in the medial layer of Ccn2 knockout aortas, likely attributed to marked proteoglycan enrichment of the medial extracellular matrix. Analyses leveraging data from the Athero-Express study cohort indicated the relevance of CCN2 in established human lesions, as CCN2 correlated with SMC marker transcripts across 654 transcriptomically profiled carotid plaques. These findings were substantiated through in situ hybridization showing CCN2 expression predominantly in the fibrous cap.

CONCLUSION

This study identifies CCN2 as a major constituent of the normal artery wall, critical in regulating SMC differentiation and aorta integrity and possessing a protective role against atherosclerosis development. These findings underscore the need for further investigation into the potential effects of anti-CCN2-based therapies on the vasculature.

Beyond conventional treatment: ASGR1 Leading the new era of hypercholesterolemia management

Cardiovascular disease (CVD) remains a leading cause of mortality worldwide, with hypercholesterolemia being a major risk factor. Although various lipid-lowering therapies exist, many patients fail to achieve optimal cholesterol control, highlighting the need for novel therapeutic approaches. ASGR1 (asialoglycoprotein receptor 1), predominantly expressed on hepatocytes, has emerged as a key regulator of cholesterol metabolism and low-density lipoprotein (LDL) clearance. This receptor's ability to regulate lipid homeostasis positions it as a promising target for therapeutic intervention in hypercholesterolemia and related cardiovascular diseases. This review critically examines the biological functions and regulatory mechanisms of ASGR1 in cholesterol metabolism, with a focus on its potential as a therapeutic target for hypercholesterolemia and related cardiovascular diseases. By analyzing recent advances in ASGR1 research, this article explores its role in liver-specific pathways, the implications of ASGR1 variants in CVD risk, and the prospects for developing ASGR1-targeted therapies. This review aims to provide a foundation for future research and clinical applications in hypercholesterolemia management.

Response to retention hypothesis as a source of targets for arterial wall-directed therapies to prevent atherosclerosis: A critical review

The subendothelial retention of circulating lipoproteins on extracellular matrix proteins and proteoglycans is one of the earliest events in the development of atherosclerosis. Multiple factors, including the size, type, composition, surrounding pH, and chemical modifications to lipoproteins, influence the electrostatic interactions between relevant moieties of the apolipoproteins on lipoproteins and the glycosaminoglycans of proteoglycans. The length and chemical composition of glycosaminoglycan chains attached to proteoglycan core proteins determine the extent of initial lipoprotein binding and retention in the artery wall. The phenomena of hyperelongation of glycosaminoglycan chains is associated with initial lipid retention and later atherosclerotic plaque formation. This review includes a summary of the current literature surrounding cellular mechanisms leading to GAG chain modification and lipid retention and discusses potential therapeutic strategies to target lipoprotein:proteoglycan interactions to prevent the development and progression of atherosclerosis.

Vascular smooth muscle cell phenotypic switching in atherosclerosis

Atherosclerosis (AS) is a complex pathology process involving intricate interactions among various cells and biological processes. Vascular smooth muscle cells (VSMCs) are the predominant cell type in normal arteries, and under atherosclerotic stimuli, VSMCs respond to altered blood flow and microenvironment changes by downregulating contractile markers and switching their phenotype. This review overviews the diverse phenotypes of VSMCs, including the canonical contractile VSMCs, synthetic VSMCs, and phenotypes resembling macrophages, foam cells, myofibroblasts, osteoblasts/chondrocytes, and mesenchymal stem cells. We summarize their presumed protective and pro-atherosclerotic roles in AS development. Additionally, we underscore the molecular mechanisms and regulatory pathways governing VSMC phenotypic switching, encompassing transcriptional regulation, biochemical factors, plaque microenvironment, epigenetics, miRNAs, and the cytoskeleton, emphasizing their significance in AS development. Finally, we outline probable future research directions targeting VSMCs, offering insights into potential therapeutic strategies for AS management.

Intravascular ICG-enhanced NIRF-IVUS imaging to assess progressive atherosclerotic lesions in excised human coronary arteries

Indocyanine green (ICG)-enhanced intravascular near-infrared fluorescence (NIRF) imaging enhances the information obtained with intravascular ultrasound (IVUS) by visualizing pathobiological characteristics of atherosclerotic plaques. To advance our understanding of this hybrid method, we aimed to assess the potential of NIRF-IVUS to identify different stages of atheroma progression by characterizing ICG uptake in human pathological specimens. After excision, 15 human coronary specimens from 13 adult patients were ICG-perfused and imaged with NIRF-IVUS. All specimens were then histopathologically and immunohistochemically assessed. NIRF-IVUS imaging revealed colocalization of ICG-deposition to plaque areas of lipid accumulation, endothelial disruption, neovascularization and inflammation. Moreover, ICG concentrations were significantly higher in advanced coronary artery disease stages (p < 0.05) and correlated significantly to plaque macrophage burden (r = 0.67). Current intravascular methods fail to detect plaque biology. Thus, we demonstrate how human coronary atheroma stage can be assessed based on pathobiological characteristics uniquely captured by ICG-enhanced intravascular NIRF.

Is systemic inflammation a missing link between cardiometabolic index with mortality? Evidence from a large population-based study

BACKGROUND

This study sought to elucidate the associations of cardiometabolic index (CMI), as a metabolism-related index, with all-cause and cardiovascular mortality among the older population. Utilizing data from the National Health and Nutrition Examination Survey (NHANES), we further explored the potential mediating effect of inflammation within these associations.

METHODS

A cohort of 3029 participants aged over 65 years old, spanning six NHANES cycles from 2005 to 2016, was enrolled and assessed. The primary endpoints of the study included all-cause mortality and cardiovascular mortality utilizing data from National Center for Health Statistics (NCHS). Cox regression model and subgroup analysis were conducted to assess the associations of CMI with all-cause and cardiovascular mortality. The mediating effect of inflammation-related indicators including leukocyte, neutrophil, lymphocyte, systemic immune-inflammation index (SII), neutrophil to lymphocyte ratio (NLR) were evaluated to investigate the potential mechanism of the associations between CMI and mortality through mediation package in R 4.2.2.

RESULTS

The mean CMI among the enrolled participants was 0.74±0.66, with an average age of 73.28±5.50 years. After an average follow-up period of 89.20 months, there were 1,015 instances of all-cause deaths and 348 cardiovascular deaths documented. In the multivariable-adjusted model, CMI was positively related to all-cause mortality (Hazard Ratio (HR)=1.11, 95% CI=1.01-1.21). Mediation analysis indicated that leukocytes and neutrophils mediated 6.6% and 13.9% of the association of CMI with all-cause mortality.

CONCLUSION

Elevated CMI is positively associated with all-cause mortality in the older adults. The association appeared to be partially mediated through inflammatory pathways, indicating that CMI may serve as a valuable indicator for poor prognosis among the older population.

Multiplex Imaging for Cell Phenotyping of Early Human Atherosclerosis

BACKGROUND

Previous studies using animal models and cultured cells suggest that vascular smooth muscle cells (SMCs) and inflammatory cytokines are important players in atherogenesis. Validating these findings in human disease is critical to designing therapeutics that target these components. Multiplex imaging is a powerful tool for characterizing cell phenotypes and microenvironments using biobanked human tissue sections. However, this technology has not been applied to human atherosclerotic lesions and needs to first be customized and validated.

METHODS AND RESULTS

For validation, we created an 8-plex imaging panel to distinguish foam cells from SMC and leukocyte origins on tissue sections of early human atherosclerotic lesions (n=9). The spatial distribution and characteristics of these foam cells were further analyzed to test the association between SMC phenotypes and inflammation. Consistent with previous reports using human lesions, multiplex imaging showed that foam cells of SMC origin outnumbered those of leukocyte origin and were enriched in the deep intima, where the lipids accumulate in early atherogenesis. This new technology also found that apoptosis or the expression of pro-inflammatory cytokines were not more associated with foam cells than with nonfoam cells in early human lesions. More CD68+ SMCs were present among SMCs that highly expressed interleukin-1β. Highly inflamed SMCs showed a trend of increased apoptosis, whereas leukocytes expressing similar levels of cytokines were enriched in regions of extracellular matrix remodeling.

CONCLUSIONS

The multiplex imaging method can be applied to biobanked human tissue sections to enable proof-of-concept studies and validate theories based on animal models and cultured cells.

Increased vascular stiffness in children exposed in utero but not children exposed postnatally to emissions from a coal mine fire

Background

Chronic, low-intensity air pollution exposure has been consistently associated with increased atherosclerosis in adults. However, there was limited research regarding the implications of acute, high-intensity air pollution exposure during childhood. We aimed to determine whether there were any associations between early-life exposure to such an episode and early-life vascular function changes.

Methods

We conducted a prospective cohort study of children (<9 years old) who lived in the vicinity of the Hazelwood coal mine fire (n = 206). Vascular function was measured using noninvasive diagnostic methods including carotid intima-media thickness and pulse wave velocity (PWV). Exposure estimates were calculated from prognostic models and location diaries during the exposure period completed by each participant's parent. Linear mixed-effects models were used to determine whether there were any associations between exposure and changes in vascular outcomes at the 3- and 7-year follow-ups and over time.

Results

At the 7-year follow-up, each 10 μg/m3 increase in daily PM2.5 in utero was associated with increased PWV (β = 0.13 m/s; 95% confidence interval [CI] = 0.02, 0.24; P = 0.02). The association between in utero exposure to daily PM2.5 was not altered by adjustment for covariates, body mass index, and maternal fire stress. Each 1 µg/m3 increase in background PM2.5 was associated with increased PWV (β = 0.68 m/s; 95% CI = 0.10, 1.26; P = 0.025), in children from the in utero exposure group. There was a trend toward smaller PWV (β = -0.17 m/s; 95% CI = -0.366, 0.02) from the 3- to 7-year follow-up clinic suggesting that the deficits observed previously in children exposed postnatally did not persist.

Conclusion

There was a moderate improvement in vascular stiffness of children exposed to PM2.5 from a local coal mine fire in infancy. There was a mild increase in vascular stiffness in children exposed to PM2.5 from a local coal mine fire while their mothers were pregnant.

The anti-atherosclerotic effect of Paeonol against the lipid accumulation in macrophage-derived foam cells by inhibiting ferroptosis via the SIRT1/NRF2/GPX4 signaling pathway

Atherosclerosis (AS) is the underlying cause of many severe vascular diseases and is primarily characterized by abnormal lipid metabolism. Paeonol (Pae), a bioactive compound derived from Paeonia Suffruticosa Andr., is recognized for its significant role in reducing lipid accumulation. Our research objective is to explore the link between lipid buildup in foam cells originating from macrophages and the process of ferroptosis, and explore the effect and mechanism of Pae on inhibiting AS by regulating ferroptosis. In our animal model, ApoE-deficient mice, which were provided with a high-fat regimen to provoke atherosclerosis, were administered Pae. The treatment was benchmarked against simvastatin and ferrostatin-1. The results showed that Pae significantly reduced aortic ferroptosis and lipid accumulation in the mice. In vitro experiments further demonstrated that Pae could decrease lipid accumulation in foam cells induced by oxidized low-density lipoprotein (LDL) and challenged with the ferroptosis inducer erastin. Crucially, the protective effect of Pae against lipid accumulation was dependent on the SIRT1/NRF2/GPX4 pathway, as SIRT1 knockdown abolished this effect. Our findings suggest that Pae may offer a novel therapeutic approach for AS by inhibiting lipid accumulation through the suppression of ferroptosis, mediated by the SIRT1/NRF2/GPX4 pathway. Such knowledge has the potential to inform the creation of novel therapeutic strategies aimed at regulating ferroptosis within the context of atherosclerosis.

Mechanistic insight: Linking cardiovascular complications of inflammatory bowel disease

Cardiovascular diseases (CVD) are the leading cause of mortality worldwide despite an aggressive reduction of traditional cardiovascular risk factors. Underlying inflammatory conditions such as inflammatory bowel disease (IBD) increase the risk of developing CVD. A broad understanding of the underlying pathophysiological processes between IBD and CVD is required to treat and prevent cardiovascular events in patients with IBD. This review highlights the commonality between IBD and CVD, including dysregulated immune response, genetics, environmental risk factors, altered gut microbiome, stress, endothelial dysfunction and abnormalities, to shed light on an essential area of modern medicine.

Modeling Foam Cell Formation in A Hydrogel-Based 3D-Intimal Model: A Study of The Role of Multi-Diseases During Early Atherosclerosis

Monocyte recruitment and transmigration are crucial in atherosclerotic plaque development. The multi-disease complexities aggravate the situation and continue to be a constant concern for understanding atherosclerosis plaque development. Herein, a 3D hydrogel-based model that integrates disease-induced microenvironments is sought to be designed, allowing us to explore the early stages of atherosclerosis, specifically examining monocyte fate in multi-disease complexities. As a proof-of-concept study, murine cells are employed to develop the model. The model is constructed with collagen embedded with murine aortic smooth muscle cells and a murine endothelial monolayer lining. The model achieves in vitro disease complexities using external stimuli such as glucose and lipopolysaccharide (LPS). Hyperglycemia exhibits a significant increase in monocyte adhesion but no enhancement in monocyte transmigration and foam cell conversion compared to euglycemia. Chronic infection achieved by LPS stimulation results in a remarkable augment in initial monocyte attachment and a significant increment in monocyte transmigration and foam cells in all concentrations. Moreover, the model exhibits synergistic sensitivity under multi-disease conditions such as hyperglycemia and infection, enhancing initial monocyte attachment, cell transmigration, and foam cell formation. Additionally, western blot data prove the enhanced levels of inflammatory biomarkers, indicating the model's capability to mimic disease-induced complexities during early atherosclerosis progression.

Serum secreted phosphoprotein 1 level is associated with plaque vulnerability in patients with coronary artery disease

Background

Vulnerable plaque was associated with recurrent cardiovascular events. This study was designed to explore predictive biomarkers of vulnerable plaque in patients with coronary artery disease.

Methods

To reveal the phenotype-associated cell type in the development of vulnerable plaque and to identify hub gene for pathological process, we combined single-cell RNA and bulk RNA sequencing datasets of human atherosclerotic plaques using Single-Cell Identification of Subpopulations with Bulk Sample Phenotype Correlation (Scissor) and Weighted gene co-expression network analysis (WGCNA). We also validated our results in an independent cohort of patients by using intravascular ultrasound during coronary angiography.

Results

Macrophages were found to be strongly correlated with plaque vulnerability while vascular smooth muscle cell (VSMC), fibrochondrocyte (FC) and intermediate cell state (ICS) clusters were negatively associated with unstable plaque. Weighted gene co-expression network analysis showed that Secreted Phosphoprotein 1 (SPP1) in the turquoise module was highly correlated with both the gene module and the clinical traits. In a total of 593 patients, serum levels of SPP1 were significantly higher in patients with vulnerable plaques than those with stable plaque (113.21 [73.65 - 147.70] ng/ml versus 71.08 [20.64 - 135.68] ng/ml; P < 0.001). Adjusted multivariate regression analysis revealed that serum SPP1 was an independent determinant of the presence of vulnerable plaque. Receiver operating characteristic curve analysis indicated that the area under the curve was 0.737 (95% CI 0.697 - 0.773; P < 0.001) for adding serum SPP1 in predicting of vulnerable plaques.

Conclusion

Elevated serum SPP1 levels confer an increased risk for plaque vulnerability in patients with coronary artery disease.

Eradicating Atherosclerotic Events by Targeting Early Subclinical Disease: It Is Time to Retire the Therapeutic Paradigm of Too Much, Too Late

Recent decades have seen spectacular advances in understanding and managing atherosclerotic cardiovascular disease, but paradoxically, clinical progress has stalled. Residual risk of atherosclerotic cardiovascular disease events is particularly vexing, given recognized lifestyle interventions and powerful modern medications. Why? Atherosclerosis begins early in life, yet clinical trials and mechanistic studies often emphasize terminal, end-stage plaques, meaning on the verge of causing heart attacks and strokes. Thus, current clinical evidence drives us to emphasize aggressive treatments that are delayed until patients already have advanced arterial disease. I call this paradigm "too much, too late." This brief review covers exciting efforts that focus on preventing, or finding and treating, arterial disease before its end-stage. Also included are specific proposals to establish a new evidence base that could justify intensive short-term interventions (induction-phase therapy) to treat subclinical plaques that are early enough perhaps to heal. If we can establish that such plaques are actionable, then broad screening to find them in early midlife individuals would become imperative-and achievable. You have a lump in your coronaries! can motivate patients and clinicians. We must stop thinking of a heart attack as a disease. The real disease is atherosclerosis. In my opinion, an atherosclerotic heart attack is a medical failure. It is a manifestation of longstanding arterial disease that we had allowed to progress to its end-stage, despite knowing that atherosclerosis begins early in life and despite the availability of remarkably safe and highly effective therapies. The field needs a transformational advance to shift the paradigm out of end-stage management and into early interventions that hold the possibility of eradicating the clinical burden of atherosclerotic cardiovascular disease, currently the biggest killer in the world. We urgently need a new evidence base to redirect our main focus from terminal, end-stage atherosclerosis to earlier, and likely reversible, human arterial disease.

Continuous glucose monitoring-derived time in range and CV are associated with altered tissue characteristics of the carotid artery wall in people with type 2 diabetes

AIMS/HYPOTHESIS

Previous studies have suggested that glucose variability may accelerate atherosclerosis progression in people with type 2 diabetes. Current guidelines recommend assessing glycaemic control using continuous glucose monitoring (CGM), which provides a comprehensive glycaemic profile to supplement HbA1c measurement. However, the association between CGM-derived metrics and atherosclerosis progression is not entirely clear.

METHODS

This exploratory study used baseline data and data obtained after 104 weeks from an ongoing prospective, multicentre, observational study. Six hundred study participants with type 2 diabetes and no apparent history of symptomatic cardiovascular disease underwent CGM and ultrasonographic atherosclerosis measurements of the carotid arteries, including the intima-media thickness (IMT) and grey-scale median (GSM), at baseline and 104 weeks. Non-invasive ultrasonic tissue characterisation of the carotid artery wall or plaque using the GSM reflects vascular composition. Multivariate regression models were used to analyse the association between CGM-derived indices, mainly time in range (TIR) and CV, and changes in carotid atherosclerosis index values.

RESULTS

Over the 104-week study period, there were modest increases in mean IMT (from 0.759±0.153 to 0.773±0.152 mm, p<0.001) and thickened-lesion GSM (from 43.5±19.5 to 53.9±23.5 units, p<0.001), but no significant changes in common carotid artery maximum-IMT (from 1.109±0.442 to 1.116±0.469 mm, p=0.453) or mean GSM (from 48.7±19.3 to 49.8±20.8 units, p=0.092). In a linear regression model with adjustment for possible atherosclerotic risk factors, including HbA1c, TIR and CV at baseline were significantly associated with the annual change in mean GSM (regression coefficient per 10% increase in TIR 0.52; 95% CI 0.06, 0.98; Hochberg-adjusted p value 0.038; regression coefficient per 1% increase in CV -0.12; 95% CI -0.22, -0.02; Hochberg-adjusted p value 0.038). TIR and CV at baseline were also significantly associated with the annual change in thickened-lesion GSM (regression coefficient per 10% increase in TIR 0.95; 95% CI 0.12, 1.79; Hochberg-adjusted p value 0.038; regression coefficient per 1% increase in CV -0.19; 95% CI -0.36, -0.01; Hochberg-adjusted p value 0.038). Participants who achieved target CGM-derived metrics at baseline, as proposed by an international consensus, showed significant annual changes in mean GSM compared with those who did not (0.94±6.88 vs -0.21±6.19 units/year, p=0.007).

CONCLUSIONS/INTERPRETATION

TIR and CV were significantly associated with changes in the tissue characteristics of the carotid artery wall.

TRIAL REGISTRATION

University Hospital Medical Information Network Clinical Trials Registry, number UMIN000032325.

The microenvironment of the atheroma expresses phenotypes of plaque instability

Data from histopathology studies of human atherosclerotic tissue specimens and from vascular imaging studies support the concept that the local arterial microenvironment of a stable atheroma promotes destabilizing conditions that result in the transition to an unstable atheroma. Destabilization is characterized by several different plaque phenotypes that cause major clinical events such as acute coronary syndrome and cerebrovascular strokes. There are several rupture-associated phenotypes causing thrombotic vascular occlusion including simple fibrous cap rupture of an atheroma, fibrous cap rupture at site of previous rupture-and-repair of an atheroma, and nodular calcification with rupture. Endothelial erosion without rupture has more recently been shown to be a common phenotype to promote thrombosis as well. Microenvironment features that are linked to these phenotypes of plaque instability are neovascularization arising from the vasa vasorum network leading to necrotic core expansion, intraplaque hemorrhage, and cap rupture; activation of adventitial and perivascular adipose tissue cells leading to secretion of cytokines, growth factors, adipokines in the outer artery wall that destabilize plaque structure; and vascular smooth muscle cell phenotypic switching through transdifferentiation and stem/progenitor cell activation resulting in the promotion of inflammation, calcification, and secretion of extracellular matrix, altering fibrous cap structure, and necrotic core growth. As the technology evolves, studies using noninvasive vascular imaging will be able to investigate the transition of stable to unstable atheromas in real time. A limitation in the field, however, is that reliable and predictable experimental models of spontaneous plaque rupture and/or erosion are not currently available to study the cell and molecular mechanisms that regulate the conversion of the stable atheroma to an unstable plaque.

Connecting the Dots: How Injury in the Arterial Wall Contributes to Atherosclerotic Disease

PURPOSE

The occurrence and development of atherosclerotic cardiovascular disease, which can result in severe outcomes, such as myocardial infarction, stroke, loss of limb, renal failure, and infarction of the gut, are strongly associated with injury to the intimal component of the arterial wall whether via the inside-out or outside-in pathways. The role of injury to the tunica media as a pathway of atherosclerosis initiation is an underresearched area. This review focuses on potential pathways to vessel wall injury as well as current experimental and clinical research in the middle-aged and elderly populations, including the role of exercise, as it relates to injury to the tunica media.

METHODS

A database search using PubMed and Google Scholar was conducted for research articles published between 1909 and 2023 that focused on pathways of atherogenesis and the impact of mechanical forces on wall injury. The following key words were searched: wall injury, tunica media, atherogenesis, vascular aging, and wall strain. Studies were analyzed, and the relevant information was extracted from each study.

FINDINGS

A link between high mechanical stress in the arterial wall and reduced vascular compliance was found. The stiffening and calcification of the arterial wall with aging induce high blood pressure and pulse pressure, thereby causing incident hypertension and cardiovascular disease. In turn, prolonged high mechanical stress, particularly wall strain, applied to the arterial wall during vigorous exercise, results in stiffening and calcification of tunica media, accelerated arterial aging, and cardiovascular disease events. In both scenarios, the tunica media is the primary target of mechanical stress and the first to respond to hemodynamic changes. The cyclical nature of these impacts confounds the results of each because they are not mutually exclusive.

IMPLICATIONS

The role of stress in the tunica media appears to be overlooked despite its relevance, and further research into new primary preventive therapies is needed aside from cautioning the role of vigorous exercise in the elderly population.

The Greatly Under-Represented Role of Smooth Muscle Cells in Atherosclerosis

PURPOSE OF REVIEW

This article summarizes previous and recent research on the fundamental role of arterial smooth muscle cells (SMCs) as drivers of initial and, along with macrophages, later stages of human atherosclerosis.

RECENT FINDINGS

Studies using human tissues and SMC lineage-tracing mice have reinforced earlier observations that SMCs drive initial atherogenesis in humans and contribute a multitude of phenotypes including foam cell formation hitherto attributed primarily to macrophages in atherosclerosis. Arterial smooth muscle cells (SMCs) are the primary cell type in human pre-atherosclerotic intima and are responsible for the retention of lipoproteins that drive the development of atherosclerosis. Despite this, images of atherogenesis still depict the process as initially devoid of SMCs, primarily macrophage driven, and indicate only relatively minor roles such as fibrous cap formation to intimal SMCs. This review summarizes historical and recent observations regarding the importance of SMCs in the formation of a pre-atherosclerotic intima, initial and later foam cell formation, and the phenotypic changes that give rise to multiple different roles for SMCs in human and mouse lesions. Potential SMC-specific therapies in atherosclerosis are presented.

Adventitial Vasa Vasorum Neovascularization in Femoral Artery of Type 2 Diabetic Patients with Macroangiopathy Is Associated with Macrophages and Lymphocytes as well as the Occurrence of Cardiovascular Events

OBJECTIVES

 This study was conducted to assess the relationship between adventitial vasa vasorum neovascularization (VVn) in femoral artery of type 2 diabetic patients with macroangiopathy and the recruitment of macrophages and lymphocytes, and to relate the density of VVn to the occurrence of cardiovascular events.

MATERIALS

 Femoral artery samples were obtained from amputation cases. A total of 55 type 2 diabetic patients with macroangiopathy, 15 autopsy cases with type 2 diabetes without atherosclerosis.

METHODS

 Hematoxylin and eosin (H&E) staining to observe the histopathological features; Victoria blue staining to analyze the histological features; immunohistochemistry (CD34, CD68, CD20, and CD3) to determine the VVn density and the expression of macrophages, B lymphocytes, and T lymphocytes.

RESULTS

 Type 2 diabetic patients with macroangiopathy showed a higher mean adventitial VVn density in femoral artery (48.40 ± 9.39 no./mm2) than patients with type 2 diabetes without atherosclerosis (19.75 ± 6.28 no./mm2) (p < 0.01). In addition, the VVn density was positively associated with the expression of CD68 macrophages (r = 0.62, p < 0.01) and CD20 B lymphocytes (r = 0.59, p < 0.01). Type 2 diabetic patients with high VVn density showed more adverse cardiovascular events (27/35 vs. 8/20 events, p = 0.006). In multivariable analysis adjusted for main risk factors for cardiovascular disease, VVn was still independently associated with adverse cardiovascular events (p = 0.01).

CONCLUSION

 VVn density in type 2 diabetic patients with macroangiopathy is positively correlated with the adventitial immune-inflammatory cell numbers and the development of atherosclerotic lesions. Furthermore, VVn density is associated with adverse cardiovascular events.

Progression of Arterial Vasa Vasorum from Regulator of Arterial Homeostasis to Promoter of Atherogenesis

The vasa vasorum (vessels of vessels) are a dynamic microvascular system uniquely distributed to maintain physiological homeostasis of the artery wall by supplying nutrients and oxygen to the outer layers of the artery wall, adventitia, and perivascular adipose tissue, and in large arteries, to the outer portion of the medial layer. Vasa vasorum endothelium and contractile mural cells regulate direct access of bioactive cells and factors present in both the systemic circulation and the arterial perivascular adipose tissue and adventitia to the artery wall. Experimental and human data show that proatherogenic factors and cells gain direct access to the artery wall via the vasa vasorum and may initiate, promote, and destabilize the plaque. Activation and growth of vasa vasorum occur in all blood vessel layers primarily by angiogenesis, producing fragile and permeable new microvessels that may cause plaque hemorrhage and fibrous cap rupture. Ironically, invasive therapies, such as angioplasty and coronary artery bypass grafting, injure the vasa vasorum, leading to treatment failures. The vasa vasorum function both as a master integrator of arterial homeostasis and, once perturbed or injured, as a promotor of atherogenesis. Future studies need to be directed at establishing reliable in vivo and in vitro models to investigate the cellular and molecular regulation of the function and dysfunction of the arterial vasa vasorum.

Membrane Cholesterol Interactions with Proteins in Hypercholesterolemia-Induced Endothelial Dysfunction

PURPOSE OF REVIEW

The goal of this review is to highlight work identifying mechanisms driving hypercholesterolemia-mediated endothelial dysfunction. We specifically focus on cholesterol-protein interactions and address specific questions related to the impact of hypercholesterolemia on cellular cholesterol and vascular endothelial function. We describe key approaches used to determine the effects of cholesterol-protein interactions in mediating endothelial dysfunction under dyslipidemic conditions.

RECENT FINDINGS

The benefits of removing the cholesterol surplus on endothelial function in models of hypercholesterolemia is clear. However, specific mechanisms driving cholesterol-induced endothelial dysfunction need to be determined. In this review, we detail the latest findings describing cholesterol-mediated endothelial dysfunction, highlighting our studies indicating that cholesterol suppresses endothelial Kir2.1 channels as a major underlying mechanism. The findings detailed in this review support the targeting of cholesterol-induced suppression of proteins in restoring endothelial function in dyslipidemic conditions. The identification of similar mechanisms regarding other cholesterol-endothelial protein interactions is warranted.

Aortic Wall Thickness as a Surrogate for Subclinical Atherosclerosis in Familial and Nonfamilial Hypercholesterolemia: Quantitative 3D Magnetic Resonance Imaging Study and Interrelations with Computed Tomography Calcium Scores, and Carotid Ultrasonography

We aimed to compare the extent of subclinical atherosclerosis in the ascending and descending aortas by measuring wall area and thickness using 3D cardiovascular magnetic resonance imaging (aAWAI and dAWAI) in patients with asymptomatic familial hypercholesterolemia (FH) and nonfamilial hypercholesterolemia (NFH). We also aimed to establish the interrelations of CMR parameters with other subclinical atherosclerosis measurements, such as calcium scores, obtained using computed tomography in coronary arteries (CCS) and ascending and descending aorta (TCSasc and TCSdsc), as well as the carotid intima-media thicknesses (cIMT) using ultrasonography. A total of 60 patients with FH (29 men and 31 women), with a mean age of 52.3 ± 9.6 years, were analyzed. A subclinical atherosclerosis assessment was also performed on a group consisting of 30 age- and gender-matched patients with NFH, with a mean age of 52.5 ± 7.9 years. We found the ascending and descending aortic wall areas and thicknesses in the FH group to be significantly increased than those of the NFH group. A multivariate logistic regression analysis showed that a positive FH mutation value was a strong predictor of high aAWAI and dAWAI independent of the LDL cholesterol level. Correlations across CMR atherosclerotic parameters, calcium scores, and cIMT in the FH and NFH groups, were significant but low. Most of the atherosclerosis tests with high results belonged to the FH group. We found that patients with documented heterozygous FH had a higher atherosclerosis burden in the aorta compared to patients with severe hypercholesterolemia without FH gene mutation. Atherosclerosis is not severe in asymptomatic patients with FH, but is more pronounced and also more diffuse than in patients with NFH. The etiology of hypercholesterolemia, and not just cholesterol levels, plays a significant role in determining the degree of subclinical atherosclerosis.

Dickkopf-1 promotes vascular smooth muscle cell foam cell formation and atherosclerosis development through CYP4A11/SREBP2/ABCA1

Vascular smooth muscle cells (VSMCs) are considered to be a crucial source of foam cells in atherosclerosis due to their low expression level of cholesterol exporter ATP-binding cassette transporter A1 (ABCA1) intrinsically. While the definite regulatory mechanisms are complicated and have not yet been fully elucidated, we previously reported that Dickkopf-1 (DKK1) mediates endothelial cell (EC) dysfunction, thereby aggravating atherosclerosis. However, the role of smooth muscle cell (SMC) DKK1 in atherosclerosis and foam cell formation remains unknown. In this study, we established SMC-specific DKK1-knockout (DKK1SMKO ) mice by crossbreeding DKK1flox/flox mice with TAGLN-Cre mice. Then, DKK1SMKO mice were crossed with APOE-/- mice to generate DKK1SMKO /APOE-/- mice, which exhibited milder atherosclerotic burden and fewer SMC foam cells. In vitro loss- and gain-of-function studies of DKK1 in primary human aortic smooth muscle cells (HASMCs) have proven that DKK1 prevented oxidized lipid-induced ABCA1 upregulation and cholesterol efflux and promoted SMC foam cell formation. Mechanistically, RNA-sequencing (RNA-seq) analysis of HASMCs as well as chromatin immunoprecipitation (ChIP) experiments showed that DKK1 mediates the binding of transcription factor CCAAT/enhancer-binding protein delta (C/EBPδ) to the promoter of cytochrome P450 epoxygenase 4A11 (CYP4A11) to regulate its expression. In addition, CYP4A11 as well as its metabolite 20-HETE-promoted activation of transcription factor sterol regulatory element-binding protein 2 (SREBP2) mediated the DKK1 regulation of ABCA1 in SMC. Furthermore, HET0016, the antagonist of CYP4A11, has also shown an alleviating effect on atherosclerosis. In conclusion, our results demonstrate that DKK1 promotes SMC foam cell formation during atherosclerosis via a reduction in CYP4A11-20-HETE/SREBP2-mediated ABCA1 expression.

The Shear Stress-Regulated Expression of Glypican-4 in Endothelial Dysfunction In Vitro and Its Clinical Significance in Atherosclerosis

Retention of circulating lipoproteins by their interaction with extracellular matrix molecules has been suggested as an underlying mechanism for atherosclerosis. We investigated the role of glypican-4 (GPC4), a heparan sulfate (HS) proteoglycan, in the development of endothelial dysfunction and plaque progression; Expression of GPC4 and HS was investigated in human umbilical vein/artery endothelial cells (HUVECs/HUAECs) using flow cytometry, qPCR, and immunofluorescent staining. Leukocyte adhesion was determined in HUVECs in bifurcation chamber slides under dynamic flow. The association between the degree of inflammation and GPC4, HS, and syndecan-4 expressions was analyzed in human carotid plaques; GPC4 was expressed in HUVECs/HUAECs. In HUVECs, GPC4 protein expression was higher in laminar than in non-uniform shear stress regions after a 1-day or 10-day flow (p < 0.01 each). The HS expression was higher under laminar flow after a 1 day (p < 0.001). Monocytic THP-1 cell adhesion to HUVECs was facilitated by GPC4 knock-down (p < 0.001) without affecting adhesion molecule expression. GPC4 and HS expression was lower in more-inflamed than in less-inflamed plaque shoulders (p < 0.05, each), especially in vulnerable plaque sections; Reduced expression of GPC4 was associated with atherogenic conditions, suggesting the involvement of GPC4 in both early and advanced stages of atherosclerosis.

The inflammatory oxidant peroxynitrous acid modulates the structure and function of the recombinant human V3 isoform of the extracellular matrix proteoglycan versican

Continued oxidant production during chronic inflammation generates host tissue damage, with this being associated with pathologies including atherosclerosis. Atherosclerotic plaques contain modified proteins that may contribute to disease development, including plaque rupture, the major cause of heart attacks and strokes. Versican, a large extracellular matrix (ECM) chondroitin-sulfate proteoglycan, accumulates during atherogenesis, where it interacts with other ECM proteins, receptors and hyaluronan, and promotes inflammation. As activated leukocytes produce oxidants including peroxynitrite/peroxynitrous acid (ONOO^-/ONOOH) at sites of inflammation, we hypothesized that versican is an oxidant target, with this resulting in structural and functional changes that may exacerbate plaque development. The recombinant human V3 isoform of versican becomes aggregated on exposure to ONOO^-/ONOOH. Both reagent ONOO^-/ONOOH and SIN-1 (a thermal source of ONOO^-/ONOOH) modified Tyr, Trp and Met residues. ONOO^-/ONOOH mainly favors nitration of Tyr, whereas SIN-1 mostly induced hydroxylation of Tyr, and oxidation of Trp and Met. Peptide mass mapping indicated 26 sites with modifications (15 Tyr, 5 Trp, 6 Met), with the extent of modification quantified at 16. Multiple modifications, including the most extensively nitrated residue (Tyr¹⁶¹), are within the hyaluronan-binding region, and associated with decreased hyaluronan binding. ONOO^-/ONOOH modification also resulted in decreased cell adhesion and increased proliferation of human coronary artery smooth muscle cells. Evidence is also presented for colocalization of versican and 3-nitrotyrosine epitopes in advanced (type II-III) human atherosclerotic plaques. In conclusion, versican is readily modified by ONOO^-/ONOOH, resulting in chemical and structural modifications that affect protein function, including hyaluronan binding and cell interactions.

Atherosclerotic carotid plaque characteristics vary with time from ischemic event: A multicenter, prospective magnetic resonance vessel wall imaging registry study

Recent studies report that the rate of recurrent stroke is highest in the stages immediately following cerebral infarction and decreases over time in patients with atherosclerotic carotid stenosis. The purpose of this study was to identify temporal differences in early stage carotid plaque components from acute cerebrovascular ischemic events using carotid MRI. Carotid plaque images were obtained on 3 T MRI from 128 patients enrolled in MR-CAS. Among the 128 subjects, 53 were symptomatic and 75 asymptomatic. The symptomatic patients were classified into three groups based on interval from onset of symptoms to the date of the carotid MRI (Group <14 days; 15-30 days; and > 30 days). The volume of each plaque component was identified and quantified from MR images. The presence of juxtaluminal loose matrix/inflammation (LM/I) was identified as a possible indicator of inflammation on the luminal side. Plaque components were compared between groups using the Wilcoxon rank-sum or the Chi-square test. Patient characteristics and carotid plaque morphology were similar among all four groups. The median volume of LM/I in Group >30 days was significantly lower than in other groups (0 mm3 vs 12.3 mm3 and 18.1 mm3; p = 0.003). In addition, the prevalence of juxtaluminal LM/I decreased over time (ptrend = 0.002). There were no statistically significant differences in other plaque components between the symptomatic groups. The volume of LM/I was significantly smaller in Group >30 days and prevalence of juxtaluminal LM/I in the atherosclerotic carotid plaque was high in the early stages after events. This suggests that carotid plaques undergo rapid evolution after an acute cerebrovascular ischemic event.

Gαq Is the Specific Mediator of PAR-1 Transactivation of Kinase Receptors in Vascular Smooth Muscle Cells

AIMS

G protein-coupled receptor (GPCR) transactivation of kinase receptors greatly expands the actions attributable to GPCRs. Thrombin, via its cognate GPCR, protease-activated receptor (PAR)-1, transactivates tyrosine and serine/threonine kinase receptors, specifically the epidermal growth factor receptor and transforming growth factor-β receptor, respectively. PAR-1 transactivation-dependent signalling leads to the modification of lipid-binding proteoglycans involved in the retention of lipids and the development of atherosclerosis. The mechanisms of GPCR transactivation of kinase receptors are distinct. We aimed to investigate the role of proximal G proteins in transactivation-dependent signalling.

MAIN METHODS

Using pharmacological and molecular approaches, we studied the role of the G⍺ subunits, G⍺q and G⍺11, in the context of PAR-1 transactivation-dependent signalling leading to proteoglycan modifications.

KEY FINDINGS

Pan G⍺q subunit inhibitor UBO-QIC/FR900359 inhibited PAR-1 transactivation of kinase receptors and proteoglycans modification. The G⍺q/11 inhibitor YM254890 did not affect PAR-1 transactivation pathways. Molecular approaches revealed that of the two highly homogenous G⍺q members, G⍺q and G⍺11, only the G⍺q was involved in regulating PAR-1 mediated proteoglycan modification. Although G⍺q and G⍺11 share approximately 90% homology at the protein level, we show that the two isoforms exhibit different functional roles.

SIGNIFICANCE

Our findings may be extrapolated to other GPCRs involved in vascular pathology and highlight the need for novel pharmacological tools to assess the role of G proteins in GPCR signalling to expand the preeminent position of GPCRs in human therapeutics.

The critical issue linking lipids and inflammation: Clinical utility of stopping oxidative stress

The formation of an atheroma begins when lipoproteins become trapped in the intima. Entrapped lipoproteins become oxidized and activate the innate immune system. This immunity represents the primary association between lipids and inflammation. When the trapping continues, the link between lipids and inflammation becomes chronic and detrimental, resulting in atherosclerosis. When entrapment ceases, the association between lipids and inflammation is temporary and healthy, and the atherogenic process halts. Therefore, the link between lipids and inflammation depends upon lipoprotein retention in the intima. The entrapment is due to electrostatic forces uniting apolipoprotein B to polysaccharide chains on intimal proteoglycans. The genetic transformation of contractile smooth muscle cells in the media into migratory secretory smooth muscle cells produces the intimal proteoglycans. The protein, platelet-derived growth factor produced by activated platelets, is the primary stimulus for this genetic change. Oxidative stress is the main stimulus to activate platelets. Therefore, minimizing oxidative stress would significantly reduce the retention of lipoproteins. Less entrapment decreases the association between lipids and inflammation. More importantly, it would halt atherogenesis. This review will analyze oxidative stress as the critical link between lipids, inflammation, and the pathogenesis of atherosclerosis. Through this perspective, we will discuss stopping oxidative stress to disrupt a harmful association between lipids and inflammation. Numerous therapeutic options will be discussed to mitigate oxidative stress. This paper will add a new meaning to the Morse code distress signal SOS-stopping oxidative stress.

Lysosomal acid lipase deficiency: A rare inherited dyslipidemia but potential ubiquitous factor in the development of atherosclerosis and fatty liver disease

Lysosomal acid lipase (LAL), encoded by the gene LIPA, is the sole neutral lipid hydrolase in lysosomes, responsible for cleavage of cholesteryl esters and triglycerides into their component parts. Inherited forms of complete (Wolman Disease, WD) or partial LAL deficiency (cholesteryl ester storage disease, CESD) are fortunately rare. Recently, LAL has been identified as a cardiovascular risk gene in genome-wide association studies, though the directionality of risk conferred remains controversial. It has also been proposed that the low expression and activity of LAL in arterial smooth muscle cells (SMCs) that occurs inherently in nature is a likely determinant of the propensity of SMCs to form the majority of foam cells in atherosclerotic plaque. LAL also likely plays a potential role in fatty liver disease. This review highlights the nature of LAL gene mutations in WD and CESD, the association of LAL with prediction of cardiovascular risk from genome-wide association studies, the importance of relative LAL deficiency in SMC foam cells, and the need to further interrogate the pathophysiological impact and cell type-specific role of enhancing LAL activity as a novel treatment strategy to reduce the development and induce the regression of ischemic cardiovascular disease and fatty liver.

The Impaired Mechanism and Facilitated Therapies of Efferocytosis in Atherosclerosis

ABSTRACT

Cardiovascular disease is responsible for the largest number of deaths worldwide, and atherosclerosis is the primary cause. Apoptotic cell accumulation in atherosclerotic plaques leads to necrotic core formation and plaque rupture. Emerging findings show that the progression of atherosclerosis appears to suppress the elimination of apoptotic cells. Mechanistically, the reduced edibility of apoptotic cells, insufficient phagocytic capacity of phagocytes, downregulation of bridging molecules, and dysfunction in the polarization of macrophages lead to impaired efferocytosis in atherosclerotic plaques. This review focuses on the characteristics of efferocytosis in plaques and the therapeutic strategies aimed at promoting efferocytosis in atherosclerosis, which would provide novel insights for the development of antiatherosclerotic drugs based on efferocytosis.

Shear stress and intravascular pressure effects on vascular dynamics: two-phase blood flow in elastic microvessels accounting for the passive stresses

We study the steady hemodynamics in physiological elastic microvessels proposing an advanced fluid-structure interaction model. The arteriolar tissue is modeled as a two-layer fiber-reinforced hyperelastic material representing its Media and Adventitia layers. The constitutive model employed (Holzapfel et al. in J Elast 61:1-48, 2000) is parametrized via available data on stress-strain experiments for arterioles. The model is completed by simulating the blood/plasma flow in the lumen, using the thixotropic elasto-viscoplastic model in its core, and the linear Phan-Thien and Tanner viscoelastic model in its annular part. The Cell-Free Layer (CFL) and the Fåhraeus and Fåhraeus-Lindqvist effects are considered via analytical expressions based on experimental data (Giannokostas et al. in Materials (Basel) 14:367, 2021b). The coupling between tissue deformation and blood flow is achieved through the experimentally verified pressure-shear hypothesis (Pries et al. Circ Res 77:1017-1023, 1995). Our calculations confirm that the increase in the reference inner radius produces larger expansion. Also, by increasing the intraluminal pressure, the thinning of the walls is more pronounced and it may reach 40% of the initial thickness. Comparing our predictions with those in rigid-wall microtubes, we conclude that apart from the vital importance of vasodilation, there is an up to 25% reduction in wall shear stress. The passive vasodilation contributes to the decrease in the tissue stress fields and affects the hemodynamic features such as the CFL thickness, reducing the plasma layer when blood flows in vessels with elastic walls, in quantitative agreement with previous experiments. Our calculations verify the correctness of the pressure-shear hypothesis but not that of the Laplace law.

Association of carotid wall layers with atherosclerotic plaques and cardiac hypertrophy in hypertensive subjects

Carotid intima-media thickness (cIMT) is considered a marker of subclinical atherosclerosis and is related to target-organ damage in hypertensive patients. However, increased cIMT may be due to increases in the thickness of intima (cIT) and media (cMT) layers. This study evaluated whether cIMT layers (cIT and cMT) had a greater association with carotid atherosclerotic plaques and left ventricular hypertrophy (LVH) than cIMT in hypertensive subjects. We cross-sectionally evaluated clinical, carotid, and echocardiography characteristics of 186 hypertensive patients followed at an outpatient clinic. High-resolution images of common carotid arteries were obtained by ultrasonography equipped with 10-MHz transducers, and cIT, cMT, and cIMT were manually measured using an image-processing software. Among all participants (n = 186; age = 60.8 ± 10.9 years, 43% males), there were 58% with carotid plaques and 58% with LVH. Mean cIT, cMT, and cIMT values were 0.267 ± 0.060, 0.475 ± 0.107, and 0.742 ± 0.142 mm, respectively. In logistic regression analysis adjusted for relevant covariates, carotid plaques showed stronger association with cIT than with cMT and cIMT. Furthermore, cIT showed greater area under the ROC curve (0.92; 95% CI 0.87-0.96) than cIMT (0.79; 95% CI 0.72-0.85) and cMT (0.64; 95% CI 0.56-0.72) to identify plaques. Conversely, cIT, cMT, and cIMT had modest association and accuracy to identify LVH (area under the ROC curve = 0.61, 0.57, and 0.60, respectively). In conclusion, cIT is a more accurate marker of atherosclerosis than cMT or cIMT, while cIT and cMT provide no incremental value in identifying LVH when compared with cIMT among hypertensive subjects.

Smooth Muscle Cell—Macrophage Interactions Leading to Foam Cell Formation in Atherosclerosis: Location, Location, Location

Cholesterol-overloaded cells or “foam cells” in the artery wall are the biochemical hallmark of atherosclerosis, and are responsible for much of the growth, inflammation and susceptibility to rupture of atherosclerotic lesions. While it has previously been thought that macrophages are the main contributor to the foam cell population, recent evidence indicates arterial smooth muscle cells (SMCs) are the source of the majority of foam cells in both human and murine atherosclerosis. This review outlines the timeline, site of appearance and proximity of SMCs and macrophages with lipids in human and mouse atherosclerosis, and likely interactions between SMCs and macrophages that promote foam cell formation and removal by both cell types. An understanding of these SMC-macrophage interactions in foam cell formation and regression is expected to provide new therapeutic targets to reduce the burden of atherosclerosis for the prevention of coronary heart disease, stroke and peripheral vascular disease.

pH-Dependent Protonation of Histidine Residues Is Critical for Electrostatic LDL (Low-Density Lipoprotein) Binding to Human Coronary Arteries

BACKGROUND

The initiating step in atherogenesis is the electrostatic binding of LDL (low-density lipoprotein) to proteoglycan glycosaminoglycans in the arterial intima. However, although proteoglycans are widespread throughout the intima of most coronary artery segments, LDL is not evenly distributed, indicating that LDL retention is not merely dependent on the presence of proteoglycans. We aim to identify factors that promote the interaction between LDL and the vessel wall of human coronary arteries.

METHODS

We developed an ex vivo model to investigate binding of human-labeled LDL to human coronary artery sections without the interference of cellular processes.

RESULTS

By staining consecutive sections of human coronary arteries, we found strong staining of sulfated glycosaminoglycans throughout the arterial intima, whereas endogenous LDL deposits were focally distributed. Ex vivo binding of LDL was uniform in all intimal areas with sulfated glycosaminoglycans. However, lowering the pH from 7.4 to 6.5 triggered a 35-fold increase in LDL binding. The pH-dependent binding was abolished by pretreating LDL with diethyl-pyrocarbonate, which blocks the protonation of histidine residues, or cyclohexanedione, which inhibits the positive charge of site B on LDL. Thus, both histidine protonation and site B are required for strong electrostatic LDL binding to the intima.

CONCLUSIONS

This study identifies histidine protonation as an important component for electrostatic LDL binding to human coronary arteries. Our findings show that the local pH will have a profound impact on LDL's affinity for sulfated glycosaminoglycans, which may influence the retention and accumulation pattern of LDL in the arterial vasculature.

Peroxynitrous acid-modified extracellular matrix alters gene and protein expression in human coronary artery smooth muscle cells and induces a pro-inflammatory phenotype

Leukocytes produce oxidants at inflammatory sites, including within the artery wall during the development of atherosclerosis. Developing lesions contain high numbers of activated leukocytes that generate reactive nitrogen species, including peroxynitrite/peroxynitrous acid (ONOO^-/ONOOH), as evidenced by the presence of oxidized/nitrated molecules including extracellular matrix (ECM) proteins. ECM materials are critical for arterial wall integrity, function, and determine cell phenotype, with smooth muscle cells undergoing a phenotypic switch from quiescent/contractile to proliferative/synthetic during disease development. We hypothesized that ECM modification by ONOO^-/ONOOH might drive this switch, and thereby potentially contribute to atherogenesis. ECM generated by primary human coronary artery smooth muscle cells (HCASMCs) was treated with increasing ONOO^-/ONOOH concentrations (1-1000 μM). This generated significant damage on laminin, fibronectin and versican, and lower levels on collagens and glycosaminoglycans, together with the increasing concentrations of the damage biomarker 3-nitrotyrosine. Adhesion of naïve HCASMC to ECM modified by 1 μM ONOO^-/ONOOH was enhanced, but significantly diminished by higher ONOO^-/ONOOH treatment. Cell proliferation and metabolic activity were significantly enhanced by 100 μM ONOO^-/ONOOH pre-treatment. These changes were accompanied by increased expression of genes involved in mitosis (PCNA, CCNA1, CCNB1), ECM (LAMA4, LAMB1, VCAN, FN1) and inflammation (IL-1B, IL-6, VCAM-1), and corresponding protein secretion (except VCAM-1) into the medium. These changes induced by modified ECM are consistent with HCASMC switching to a synthetic/proliferative/pro-inflammatory phenotype, together with ECM remodelling. These changes model those in atherosclerosis, suggesting a link between oxidant-modified ECM and disease progression, and highlight the potential of targeting oxidant generation as a therapeutic strategy.

Endothelin-1 dependent expression of GAG genes involves NOX and p38 mediated Smad linker region phosphorylation

Endothelin-1 (ET-1) is implicated in the development of atherosclerosis and mediates glycosaminoglycan (GAG) chain hyperelongation on proteoglycans. Our aim was to identify the ET-1-mediated signalling pathway involving NADPH oxidase (NOX), p38 MAP kinsae and Smad2 linker region phosphorylation (phospho-Smad2L) regulate GAG synthesizing enzymes mRNA expression (C4ST-1 and ChSy1) involved in GAG chains hyperelongation in human vascular smooth muscle cells (VSMCs). Signalling intermediates were detected and quantified by Western blotting and the mRNA levels of GAG synthesizing enzymes were assessed by quantitative real-time polymerase chain reaction (qRT-PCR). ET-1 treatment of human VSMCs resulted in an increase in phospho-Smad2L level. The TGF-β receptor antagonist, SB431542 and the mixed ET_A and ET_B receptor antagonist bosentan, inhibited ET-1-mediated phospho-Smad2L level. In the presence of apocynin and diphenyleneiodonium chloride (DPI) (NOX inhibitors) and SB239063 (p38 inhibitor) ET-1-mediated phospho-Smad2L levels were inhibited. The gene expression levels of GAG synthesizing enzymes post-ET-1 treatment were increased compared to untreated controls (P<0.01). The ET-mediated the mRNA levels of these enzymes were blocked by the bosentan, SB431542, SB239063, DPI, apocynin and antioxidant N-acetyl-L-cysteine (NAC). ET-1-mediated signalling to GAG synthesizing enzymes gene expression occurs via transactivation-dependent pathway involving NOX, p38 MAP kinsae and Smad2 linker region phosphorylation. This article is protected by copyright. All rights reserved.

Atherogenesis, Transcytosis, and the Transmural Cholesterol Flux: A Critical Review

The recently described phenomenon of cholesterol-loaded low-density lipoproteins (LDL) entering the arterial wall from the lumen by transcytosis has been accepted as an alternative for the long-held concept that atherogenesis involves only passive LDL movement across an injured or dysfunctional endothelial barrier. This active transport of LDL can now adequately explain why plaques (atheromas) appear under an intact, uninjured endothelium. However, the LDL transcytosis hypothesis is still questionable, mainly because the process serves no clear physiological purpose. Moreover, central components of the putative LDL transcytosis apparatus are shared by the counter process of cholesterol efflux and reverse cholesterol transport (RCT) and therefore can essentially create an energy-wasting futile cycle and paradoxically be pro- and antiatherogenic simultaneously. Hence, by critically reviewing the literature, we wish to put forward an alternative interpretation that, in our opinion, better fits the experimental evidence. We assert that most of the accumulating cholesterol (mainly as LDL) reaches the intima not from the lumen by transcytosis, but from the artery's inner layers: the adventitia and media. We have named this directional cholesterol transport transmural cholesterol flux (TCF). We suggest that excess cholesterol, diffusing from the avascular (i.e., devoid of blood and lymph vessels) media's smooth muscle cells, is cleared by the endothelium through its apical membrane. A plaque is formed when this cholesterol clearance rate lags behind its rate of arrival by TCF.

Alpinetin inhibits macrophage infiltration and atherosclerosis by improving the thiol redox state: Requirement of GSk3β/Fyn-dependent Nrf2 activation

Alpinetin is a plant flavonoid isolated from Alpinia katsumadai Hayata with antioxidant and anti-inflammatory properties. Monocyte infiltration into the intima promotes atherosclerotic development and causes plaque instability at the later stage, which is profoundly influenced by various oxidants. In this study, we investigated whether alpinetin restores the redox state to inhibit monocyte infiltration and ameliorates atherosclerosis. ApoE-deficient (ApoE^-/- ) mice were fed a high-fat diet and treated with alpinetin. We found that alpinetin significantly attenuated atherosclerotic lesions and reduced necrotic core size associated with the reduction in infiltrated macrophages within the plaques. Alpinetin inhibited macrophage adhesion and migration, and the expression of chemokines and adhesion molecules, such as MCP-1, VCAM-1, and ICAM-1. Intraplaque MMP2 and MMP9 were reduced, while collagen contents were increased and elastin fiber was prevented from degradation in the alpinetin-treated mice. Data further showed that alpinetin reduced reactive oxygen species generation and promoted thiol-dependent glutathione and thioredoxin antioxidant systems in macrophages. Alpinetin activated Nfr2, an upstream activator of the thiol-dependent redox signaling by increasing the nuclear translocation. The nuclear accumulation of Nrf2 was enhanced by reducing nuclear export, which was achieved through the regulation of the GSk3β/Fyn pathway. Finally, inhibition of Nrf2 in HFD-apoE^-/- mice blockaded the effect of alpinetin, which increased aortic macrophage recruitment and aggravated atherosclerosis concurrently with elevating the expression of MCP-1, VCAM-1, and ICAM-1. Altogether, these findings indicated that alpinetin improved Nrf2-mediated redox homeostasis, which consequently inhibited macrophage infiltration and atherosclerosis, suggesting a useful compound for treating atherosclerosis.

Opinion: On the Way towards the New Paradigm of Atherosclerosis

Atherosclerosis is a multicausal disease characterized by the formation of cholesterol-containing plaque in the pronounced intima nearest to the heart's elastic-type arteries that have high levels of blood circulation. Plaques are formed due to arterial pressure-induced damage to the endothelium in areas of turbulent blood flow. It is found in the majority of the Western population, including young people. This denies the monogenic mechanism of atherogenesis. In 1988, Orekhov et al. and Kawai et al. discovered that the presence of atherogenic (modified, including oxidized ones) LDLs is necessary for atherogenesis. On the basis of our discovery, suggesting that the overloading of enterocytes with lipids could lead to the formation of modified LDLs, we proposed a new hypothesis explaining the main factors of atherogenesis. Indeed, when endothelial cells are damaged and then pass through the G2 phase of their cell cycle they secrete proteins into their basement membrane. This leads to thickening of the basement membrane and increases its affinity to LDL especially for modified ones. When the enterocyte transcytosis pathway is overloaded with fat, very large chylomicrons are formed, which have few sialic acids, circulate in the blood for a long time, undergo oxidation, and can induce the production of autoantibodies. It is the sialic acids that shield the short forks of the polysaccharide chains to which autoantibodies are produced. Here, these data are evaluated from the point of view of our new model.

The garlic-derived organosulfur compound diallyl trisulphide suppresses tissue factor function

Tissue factor (TF) is a critical initiator of extrinsic coagulation that sometimes causes thromboembolism. Diallyl trisulphide (DATS) is a secondary metabolite of allicin generated in crushed garlic, with various pharmacological effects. This study aimed to clarify the effect of DATS on the extrinsic coagulation elicited by TF and arteriosclerosis. TF activity was measured using a clotting assay in TF-expressing HL60 cells. DATS inhibited TF activity in a dose-dependent manner. TF expression in TNF-α-stimulated human umbilical vein endothelial cells was examined using real-time PCR and western blotting. DATS inhibited TF mRNA and protein expression induced by TNF-α via inhibition of JNK signalling. The effect of DATS on arteriosclerosis was also examined in apolipoprotein E-deficient mice. DATS administration in these mice tended to decrease atherosclerotic lesion size. These results strongly suggest that DATS prevents thromboembolism triggered by atherosclerosis via the inhibition of plaque formation and TF function.