Foam Cells as Therapeutic Targets in Atherosclerosis with a Focus on the Regulatory Roles of Non-Coding RNAs

p-Coumaric acid modulates cholesterol efflux and lipid accumulation and inflammation in foam cells

BACKGROUND/OBJECTIVES

Atherosclerosis is a primary cause of cardiovascular disease associated with inflammation and lipid metabolism disorders. The accumulation of cholesterol-containing macrophage foam cells characterizes the early stages. The p-coumaric acid (p-CA) contained in vegetables may have various physiological activities. The inhibitory effect of p-CA on foam cell creation in THP-1 macrophages needs clarification. In this study, we explored the impact of p-CA on foam cells by co-treatment with oxidized low-density lipoprotein (ox-LDL) and lipopolysaccharides (LPS), mimicking the development of atherosclerosis in vitro and studied the regulation of its underlying mechanisms.

MATERIALS/METHODS

THP-1 cells differentiated by phorbol 12-myristate 13-acetate (1 μM) for 48 h and treated in the absence or presence of p-CA for 48 h. THP-1 macrophages were treated with combined ox-LDL (20 μg/mL) and LPS (500 ng/mL) for 24 h. The 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assays detected cell viability. Oil red O staining allowed us to observe lipid accumulation. Western blotting and quantitative polymerase chain reactions quantified corresponding proteins and mRNA.

RESULTS

Ox-LDL and LPS for 24 h enhanced the lipid accumulation using Oil red O in treated foam cells. By contrast, p-CA treatment inhibited lipid accumulation. p-CA significantly upregulated cholesterol efflux-related genes such as ATP binding cassette transporter A1, liver-X-receptor α and peroxisome proliferator-activated receptor gamma expression. Moreover, p-CA decreased lipid accumulation-related gene such as lectin-like oxidized low-density lipoprotein receptor-1, cluster of differentiation 36 and scavenger receptor class A1 expression. Combined ox-LDL and LPS increased nuclear factor-κB (NF-κB), cyclooxygenase-2 (COX-2) and pro-inflammatory (tumor necrosis factor-α [TNF-α] and interleukin [IL]-6) activation and expression compared with untreated. p-CA suppressed this increased expression of NF-κB and COX-2, TNF-α and IL-6.

CONCLUSION

p-CA may play a vital role in atherosclerosis inhibition and protective effects by suppressing lipid accumulation and foam cell creation by increasing cholesterol efflux and can be potential agents for preventing atherosclerosis.

Canonical and non-canonical roles of complement in atherosclerosis

Cardiovascular diseases are the leading cause of death globally, and atherosclerosis is the major contributor to the development and progression of cardiovascular diseases. Immune responses have a central role in the pathogenesis of atherosclerosis, with the complement system being an acknowledged contributor. Chronic activation of liver-derived and serum-circulating canonical complement sustains endothelial inflammation and innate immune cell activation, and deposition of complement activation fragments on inflamed endothelial cells is a hallmark of atherosclerotic plaques. However, increasing evidence indicates that liver-independent, cell-autonomous and non-canonical complement activities are underappreciated contributors to atherosclerosis. Furthermore, complement activation can also have atheroprotective properties. These specific detrimental or beneficial contributions of the complement system to the pathogenesis of atherosclerosis are dictated by the location of complement activation and engagement of its canonical versus non-canonical functions in a temporal fashion during atherosclerosis progression. In this Review, we summarize the classical and the emerging non-classical roles of the complement system in the pathogenesis of atherosclerosis and discuss potential strategies for therapeutic modulation of complement for the prevention and treatment of atherosclerotic cardiovascular disease.

Effect of Siegesbeckia glabrescens Extract on Foam Cell Formation in THP-1 Macrophages

The accumulation of cholesterol-bearing macrophage foam cells in the initial stages of atherosclerosis serves as a characteristic feature of atherosclerotic lesions. The inhibitory effect of Siegesbeckia glabrescens, a species of flowering plant in the Asteraceae family, on foam cell formation in THP-1 macrophages has not yet been elucidated. In this study, we explored the effect of S. glabrescens ethanol extract (SGEE) and hot water extract (SGWE) on foam cell formation via co-treatment with oxidized low density lipoprotein (ox-LDL) and lipopolysaccharide (LPS), mimicking the occurrence of atherosclerosis in vitro, and studied the regulation of its underlying mechanisms. THP-1 cells differentiated by PMA (1 μM) for 48 h were subsequently treated with/without SGWE and SGEE for 48 h. THP-1 macrophages were treated with ox-LDL (20 μg/mL) and LPS (500 ng/mL) for 24 h. Treatment with ox-LDL and LPS for 24 h enhanced the lipid accumulation in foam cells compared to in untreated cells, as determined by oil red O staining. In contrast, SGWE and SGEE treatment inhibited lipid accumulation in foam cells. Both extracts significantly upregulated ABCA1, LXRα, and PPARγ expression in ox-LDL- and LPS-treated cells (P<0.05). Moreover, both SGWE and SGEE decreased LOX-1, CD36, and SR-A1 expression. The co-treatment of ox-LDL and LPS increased NF-κB, COX-2, and pro-inflammatory activation and expression compared with untreated cells. However, this increase suppressed NF-κB, COX-2, and pro-inflammatory expression by SGWE and SGEE. The results indicated that both extracts can partially inhibit foam cell formation and contribute to protective effects by suppressing cholesterol accumulation during the onset of atherosclerosis.

Macrophages in vascular disease: Roles of mitochondria and metabolic mechanisms

Macrophages are a dynamic cell type of the immune system implicated in the pathophysiology of vascular diseases and are a major contributor to pathological inflammation. Excessive macrophage accumulation, activation, and polarization is observed in aortic aneurysm (AA), atherosclerosis, and pulmonary arterial hypertension. In general, macrophages become activated and polarized to a pro-inflammatory phenotype, which dramatically changes cell behavior to become pro-inflammatory and infiltrative. These cell types become cumbersome and fail to be cleared by normal mechanisms such as autophagy. The result is a hyper-inflammatory environment causing the recruitment of adjacent cells and circulating immune cells to further augment the inflammatory response. In AA, this leads to excessive ECM degradation and chemokine secretion, ultimately causing macrophages to dominate the immune cell landscape in the aortic wall. In atherosclerosis, monocytes are recruited to the vascular wall, where they polarize to the pro-inflammatory phenotype and induce inflammatory pathway activation. This leads to the development of foam cells, which significantly contribute to neointima and necrotic core formation in atherosclerotic plaques. Pro-inflammatory macrophages, which affect other vascular diseases, present with fragmented mitochondria and corresponding metabolic dysfunction. Targeting macrophage mitochondrial dynamics has proved to be an exciting potential therapeutic approach to combat vascular disease. This review will summarize mitochondrial and metabolic mechanisms of macrophage activation, polarization, and accumulation in vascular diseases.

Nrf2 Connects Cellular Autophagy and Vascular Senescence in Atherosclerosis: A Mini-Review

Nuclear factor erythroid 2-related factor 2 (Nrf2), a transcriptional factor that maintains intracellular redox equilibrium, modulates the expression of antioxidant genes, scavenger receptors, and cholesterol efflux transporters, all of which contribute significantly to foam cell development and plaque formation. Nrf2 has recently emerged as a key regulator that connects autophagy and vascular senescence in atherosclerosis. Autophagy, a cellular mechanism involved in the breakdown and recycling of damaged proteins and organelles, and cellular senescence, a state of irreversible growth arrest, are both processes implicated in the pathogenesis of atherosclerosis. The intricate interplay of these processes has received increasing attention, shedding light on their cumulative role in driving the development of atherosclerosis. Recent studies have revealed that Nrf2 plays a critical role in mediating autophagy and senescence in atherosclerosis progression. Nrf2 activation promotes autophagy, which increases lipid clearance and prevents the development of foam cells. Meanwhile, the activation of Nrf2 also inhibits cellular senescence by regulating the expression of senescence markers to preserve cellular homeostasis and function and delay the progression of atherosclerosis. This review provides an overview of the molecular mechanisms through which Nrf2 connects cellular autophagy and vascular senescence in atherosclerosis. Understanding these mechanisms can provide insights into potential therapeutic strategies targeting Nrf2 to modulate cellular autophagy and vascular senescence, thereby preventing the progression of atherosclerosis.

Anti-foam cell activity of metabolites of a bacterium isolated from yogurt

Existing literature documents the beneficial effects of probiotics against atherosclerosis, a major cause of human death. However, it suffers from a serious limitation due to horizontal gene transfer. Therefore, currently, efforts are targeted to examine the beneficial effects of metabolites obtained from probiotics. In this context, the current study isolated a bacterium from yogurt and investigated the effect of its metabolites on foam cell formation, a key event for developing atherosclerosis. Results showed that the cell-free conditioned medium (CM) of this isolate and di-chloro methane extract of CM (CME) not only prevented the formation but also reduced the level of preformed foam cells. To understand the mechanism, the GC-MS study revealed the presence of compounds known to exert anti-atherogenic activities like anti-oxidant, anti-NF-κB, and lipolytic activities. Consistently, CME exhibited substantial anti-oxidant and anti-NF-κB activity. In conclusion, metabolites of this bacterium have anti-atherogenic activities and thus have therapeutic potential.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01515-7.

Elucidating the role of chemokines in inflammaging associated atherosclerotic cardiovascular diseases

Age-related inflammation or inflammaging is a critical deciding factor of physiological homeostasis during aging. Cardiovascular diseases (CVDs) are exquisitely associated with aging and inflammation and are one of the leading causes of high mortality in the elderly population. Inflammaging comprises dysregulation of crosstalk between the vascular and cardiac tissues that deteriorates the vasculature network leading to development of atherosclerosis and atherosclerotic-associated CVDs in elderly populations. Leukocyte differentiation, migration and recruitment holds a crucial position in both inflammaging and atherosclerotic CVDs through relaying the activity of an intricate network of inflammation-associated protein-protein interactions. Among these interactions, small immunoproteins such as chemokines play a major role in the progression of inflammaging and atherosclerosis. Chemokines are actively involved in lymphocyte migration and severe inflammatory response at the site of injury. They relay their functions via chemokine-G protein-coupled receptors-glycosaminoglycan signaling axis and is a principal part for the detection of age-related atherosclerosis and related CVDs. This review focuses on highlighting the detailed intricacies of the effects of chemokine-receptor interaction and chemokine oligomerization on lymphocyte recruitment and its evident role in clinical manifestations of atherosclerosis and related CVDs. Further, the role of chemokine mediated signaling for formulating next-generation therapeutics against atherosclerosis has also been discussed.

The Pleiotropic Effects of Lipid-Modifying Interventions: Exploring Traditional and Emerging Hypolipidemic Therapies

Atherosclerotic cardiovascular disease poses a significant global health issue, with dyslipidemia standing out as a major risk factor. In recent decades, lipid-lowering therapies have evolved significantly, with statins emerging as the cornerstone treatment. These interventions play a crucial role in both primary and secondary prevention by effectively reducing cardiovascular risk through lipid profile enhancements. Beyond their primary lipid-lowering effects, extensive research indicates that these therapies exhibit pleiotropic actions, offering additional health benefits. These include anti-inflammatory properties, improvements in vascular health and glucose metabolism, and potential implications in cancer management. While statins and ezetimibe have been extensively studied, newer lipid-lowering agents also demonstrate similar pleiotropic effects, even in the absence of direct cardiovascular benefits. This narrative review explores the diverse pleiotropic properties of lipid-modifying therapies, emphasizing their non-lipid effects that contribute to reducing cardiovascular burden and exploring emerging benefits for non-cardiovascular conditions. Mechanistic insights into these actions are discussed alongside their potential therapeutic implications.

Integrating Computational and Biological Hemodynamic Approaches to Improve Modeling of Atherosclerotic Arteries

Atherosclerosis is the primary cause of cardiovascular disease, resulting in mortality, elevated healthcare costs, diminished productivity, and reduced quality of life for individuals and their communities. This is exacerbated by the limited understanding of its underlying causes and limitations in current therapeutic interventions, highlighting the need for sophisticated models of atherosclerosis. This review critically evaluates the computational and biological models of atherosclerosis, focusing on the study of hemodynamics in atherosclerotic coronary arteries. Computational models account for the geometrical complexities and hemodynamics of the blood vessels and stenoses, but they fail to capture the complex biological processes involved in atherosclerosis. Different in vitro and in vivo biological models can capture aspects of the biological complexity of healthy and stenosed vessels, but rarely mimic the human anatomy and physiological hemodynamics, and require significantly more time, cost, and resources. Therefore, emerging strategies are examined that integrate computational and biological models, and the potential of advances in imaging, biofabrication, and machine learning is explored in developing more effective models of atherosclerosis.

Optimisation of an in vitro human cardiovascular model on-a-chip for toxicological assessment of nicotine delivery products

Background

Smoking cigarettes is a cause of serious diseases in smokers, including cardiovascular disease. Through a pathway of endothelial dysfunction, lipid infiltration, macrophage recruitment and vascular remodeling, atherosclerosis is fundamental in the development of most cardiovascular diseases. There is an increasing number of next-generation products (NGP) which provide potentially reduced harm forms of nicotine delivery to adult smokers. This study aimed to optimise an in vitro cardiovascular model to assess such products. Human Coronary Artery Endothelial Cells (HCAECs) were cultured on an OrganoPlate®2-lane chip (Mimetas BV) combined with THP-1 monocytes under flow conditions.

Methods

An aqueous aerosol extract from the 1R6F reference cigarette was compared with two categories of NGP, (a heated tobacco product (HTP) and an electronic nicotine delivery system (ENDS)), to assess relative effects on select atherogenic endpoints (oxidative stress, monocyte adhesion, ICAM-1 expression, and inflammatory markers). Following exposure of THP-1 monocytes with the aqueous extracts, the resulting conditioned medium was then added to the HCAEC vessels.

Results

1R6F was consistently the most potent test article, eliciting observed responses at 4x lower concentrations than applied for both the HTP and ENDS. The HTP was more potent than the ENDS product across all endpoints, however, all test articles increased monocyte adhesion. ICAM-1 did not appear to be a main driver for monocyte adhesion, however, this could be due to replicate variability. Upon comparison to an extract-only control exposure, THP-1-medium pre-conditioning was an important mediator of the responses observed.

Conclusion

In conclusion, the data suggests that the NGP extracts, containing primary aerosol chemical constituents exhibit a marked reduction in biological activity in the early key events associated with atherogenesis when compared to a cigarette, adding to the weight of evidence for the tobacco harm reduction potential of such products.

The Role of Lipoprotein(a) in Peripheral Artery Disease

Lipoprotein(a) is a low-density-lipoprotein-like particle that consists of apolipoprotein(a) bound to apolipoprotein(b). It has emerged as an established causal risk factor for atherosclerotic cardiovascular disease, stroke, and aortic valve stenosis through multifactorial pathogenic mechanisms that include inflammation, atherogenesis, and thrombosis. Despite an estimated 20% of the global population having elevated lipoprotein(a) levels, testing remains underutilized due to poor awareness and a historical lack of effective and safe therapies. Although lipoprotein(a) has a strong association with coronary artery disease and cerebrovascular disease, its relationship with peripheral artery disease is less well established. In this article, we review the epidemiology, biology, and pathogenesis of lipoprotein(a) as it relates to peripheral artery disease. We also discuss emerging treatment options to help mitigate major adverse cardiac and limb events in this population.

Lipid-Laden Macrophages in Pulmonary Diseases

Pulmonary surfactants play a crucial role in managing lung lipid metabolism, and dysregulation of this process is evident in various lung diseases. Alternations in lipid metabolism lead to pulmonary surfactant damage, resulting in hyperlipidemia in response to lung injury. Lung macrophages are responsible for recycling damaged lipid droplets to maintain lipid homeostasis. The inflammatory response triggered by external stimuli such as cigarette smoke, bleomycin, and bacteria can interfere with this process, resulting in the formation of lipid-laden macrophages (LLMs), also known as foamy macrophages. Recent studies have highlighted the potential significance of LLM formation in a range of pulmonary diseases. Furthermore, growing evidence suggests that LLMs are present in patients suffering from various pulmonary conditions. In this review, we summarize the essential metabolic and signaling pathways driving the LLM formation in chronic obstructive pulmonary disease, pulmonary fibrosis, tuberculosis, and acute lung injury.

SENP3 attenuates foam cell formation by deSUMOylating NLRP3 in macrophages stimulated with ox-LDL

SUMO-specific protease 3 (SENP3) participates in the removal of SUMOylation and maintains the balance of the SUMO system, which ensures normal functioning of substrates and cellular activities. In the present study, we found that SENP3 expression was significantly reduced in ox-LDL-stimulated macrophages. SENP3 overexpression suppressed and SENP3 knockdown promoted macrophage foam cell formation. Moreover, SENP3 inhibited cholesterol uptake, CD36 expression, and NOD-like receptor thermal protein domain-associated protein 3 (NLRP3) inflammasome activation in ox-LDL-stimulated macrophages. Ox-LDL-stimulated NLRP3 SUMOylation was reduced by SENP3. Blocking NLRP3 SUMOylation inhibited foam cell formation and NLRP3 inflammasome activation. Thus, this study revealed that SENP3 inhibits macrophage foam cell formation by deSUMOylating NLRP3 and regulating NLRP3 inflammasome activation, which may provide a potentially innovative approach to treatment of atherosclerosis.

The role of nanosystems in the delivery of glucose-lowering drugs for the preemption and treatment of diabetes-associated atherosclerosis

Diabetes is one of the most prevalent diseases worldwide. In recent decades, type-2 diabetes has become increasingly common, particularly in younger individuals. Diabetes leads to many vascular complications, including atherosclerosis. Atherosclerosis is a cardiovascular disease characterized by lipid-rich plaques within the vasculature. Plaques develop over time, restricting blood flow, and can, therefore, be the underlying cause of major adverse cardiovascular events, including myocardial infarction and stroke. Diabetes and atherosclerosis are intrinsically linked. Diabetes is a metabolic syndrome that accelerates atherosclerosis and increases the risk of developing other comorbidities, such as diabetes-associated atherosclerosis (DAA). Gold standard antidiabetic medications focus on attenuating hyperglycemia. Though recent evidence suggests that glucose-lowering drugs may have broader applications, beyond diabetes management. This review mainly evaluates the role of glucagon-like peptide-1 receptor agonists (GLP-1 RAs), such as liraglutide and semaglutide in DAA. These drugs mimic gut hormones (incretins), which inhibit glucagon secretion while stimulating insulin secretion, thus improving insulin sensitivity. This facilitates delayed gastric emptying and increased patient satiety; hence, they are also indicated for the treatment of obesity. GLP-1 RAs have significant cardioprotective effects, including decreasing low-density lipoprotein (LDL) cholesterol and triglycerides levels. Liraglutide and semaglutide have specifically been shown to decrease cardiovascular risk. Liraglutide has displayed a myriad of antiatherosclerotic properties, with the potential to induce plaque regression. This review aims to address how glucose-lowering medications can be applied to treat diseases other than diabetes. We specifically focus on how nanomedicines can be used for the site-specific delivery of antidiabetic medicines for the treatment of diabetes-associated atherosclerosis.

Characterization of cell cycle, inflammation, and oxidative stress signaling role in non-communicable diseases: Insights into genetic variants, microRNAs and pathways

Non-Communicable Diseases (NCDs) significantly impact global health, contributing to over 70% of premature deaths, as reported by the World Health Organization (WHO). These diseases have complex and multifactorial origins, involving genetic, epigenetic, environmental and lifestyle factors. While Genome-Wide Association Study (GWAS) is widely recognized as a valuable tool for identifying variants associated with complex phenotypes; the multifactorial nature of NCDs necessitates a more comprehensive exploration, encompassing not only the genetic but also the epigenetic aspect. For this purpose, we employed a bioinformatics-multiomics approach to examine the genetic and epigenetic characteristics of NCDs (i.e. colorectal cancer, coronary atherosclerosis, squamous cell lung cancer, psoriasis, type 2 diabetes, and multiple sclerosis), aiming to identify novel biomarkers for diagnosis and prognosis. Leveraging GWAS summary statistics, we pinpointed Single Nucleotide Polymorphisms (SNPs) independently associated with each NCD. Subsequently, we identified genes linked to cell cycle, inflammation and oxidative stress mechanisms, revealing shared genes across multiple diseases, suggesting common functional pathways. From an epigenetic perspective, we identified microRNAs (miRNAs) with regulatory functions targeting these genes of interest. Our findings underscore critical genetic pathways implicated in these diseases. In colorectal cancer, the dysregulation of the "Cytokine Signaling in Immune System" pathway, involving LAMA5 and SMAD7, regulated by Hsa-miR-21-5p, Hsa-miR-103a-3p, and Hsa-miR-195-5p, emerged as pivotal. In coronary atherosclerosis, the pathway associated with "binding of TCF/LEF:CTNNB1 to target gene promoters" displayed noteworthy implications, with the MYC factor controlled by Hsa-miR-16-5p as a potential regulatory factor. Squamous cell lung carcinoma analysis revealed significant pathways such as "PTK6 promotes HIF1A stabilization," regulated by Hsa-let-7b-5p. In psoriasis, the "Endosomal/Vacuolar pathway," involving HLA-C and Hsa-miR-148a-3p and Hsa-miR-148b-3p, was identified as crucial. Type 2 Diabetes implicated the "Regulation of TP53 Expression" pathway, controlled by Hsa-miR-106a-5p and Hsa-miR-106b-5p. In conclusion, our study elucidates the genetic framework and molecular mechanisms underlying NCDs, offering crucial insights into potential genetic/epigenetic biomarkers for diagnosis and prognosis. The specificity of pathways and related miRNAs in different pathologies highlights promising candidates for further clinical validation, with the potential to advance personalized treatments and alleviate the global burden of NCDs.

The Role of Fatty Acid Synthase in the Vascular Smooth Muscle Cell to Foam Cell Transition

Vascular smooth muscle cells (VSMCs), in their contractile and differentiated state, are fundamental for maintaining vascular function. Upon exposure to cholesterol (CHO), VSMCs undergo dedifferentiation, adopting characteristics of foam cells-lipid-laden, macrophage-like cells pivotal in atherosclerotic plaque formation. CHO uptake by VSMCs leads to two primary pathways: ABCA1-mediated efflux or storage in lipid droplets as cholesterol esters (CEs). CE formation, involving the condensation of free CHO and fatty acids, is catalyzed by sterol O-acyltransferase 1 (SOAT1). The necessary fatty acids are synthesized by the lipogenic enzyme fatty acid synthase (FASN), which we found to be upregulated in atherosclerotic human coronary arteries. This observation led us to hypothesize that FASN-mediated fatty acid biosynthesis is crucial in the transformation of VSMCs into foam cells. Our study reveals that CHO treatment upregulates FASN in human aortic SMCs, concurrent with increased expression of CD68 and upregulation of KLF4, markers associated with the foam cell transition. Crucially, downregulation of FASN inhibits the CHO-induced upregulation of CD68 and KLF4 in VSMCs. Additionally, FASN-deficient VSMCs exhibit hindered lipid accumulation and an impaired transition to the foam cell phenotype following CHO exposure, while the addition of the fatty acid palmitate, the main FASN product, exacerbates this transition. FASN-deficient cells also show decreased SOAT1 expression and elevated ABCA1. Notably, similar effects are observed in KLF4-deficient cells. Our findings demonstrate that FASN plays an essential role in the CHO-induced upregulation of KLF4 and the VSMC to foam cell transition and suggest that targeting FASN could be a novel therapeutic strategy to regulate VSMC phenotypic modulation.

The Link between miRNAs and PCKS9 in Atherosclerosis

Cardiovascular disease (CDV) represents the major cause of death globally. Atherosclerosis, as the primary cause of CVD, is a chronic immune-inflammatory disorder with complex multifactorial pathophysiology encompassing oxidative stress, enhanced immune-inflammatory cascade, endothelial dysfunction, and thrombosis. An initiating event in atherosclerosis is the subendothelial accumulation of low-density lipoprotein (LDL), followed by the localization of macrophages to fatty deposits on blood vessel walls, forming lipid-laden macrophages (foam cells) that secrete compounds involved in plaque formation. Given the fact that foam cells are one of the key culprits that underlie the pathophysiology of atherosclerosis, special attention has been paid to the investigation of the efficient therapeutic approach to overcome the dysregulation of metabolism of cholesterol in macrophages, decrease the foam cell formation and/or to force its degradation. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secretory serine proteinase that has emerged as a significant regulator of the lipid metabolism pathway. PCSK9 activation leads to the degradation of LDL receptors (LDLRs), increasing LDL cholesterol (LDL-C) levels in the circulation. PCSK9 pathway dysregulation has been identified as one of the mechanisms involved in atherosclerosis. In addition, microRNAs (miRNAs) are investigated as important epigenetic factors in the pathophysiology of atherosclerosis and dysregulation of lipid metabolism. This review article summarizes the recent findings connecting the role of PCSK9 in atherosclerosis and the involvement of various miRNAs in regulating the expression of PCSK9-related genes. We also discuss PCSK9 pathway-targeting therapeutic interventions based on PCSK9 inhibition, and miRNA levels manipulation by therapeutic agents.

RNA interference-based therapies for atherosclerosis: Recent advances and future prospects

Atherosclerosis represents a pathological state that affects the arterial system of the organism. This chronic, progressive condition is typified by the accumulation of atheroma within arterial walls. Modulation of RNA molecules through RNA-based therapies has expanded the range of therapeutic options available for neurodegenerative diseases, infectious diseases, cancer, and, more recently, cardiovascular disease (CVD). Presently, microRNAs and small interfering RNAs (siRNAs) are the most widely employed therapeutic strategies for targeting RNA molecules, and for regulating gene expression and protein production. Nevertheless, for these agents to be developed into effective medications, various obstacles must be overcome, including inadequate binding affinity, instability, challenges of delivering to the tissues, immunogenicity, and off-target toxicity. In this comprehensive review, we discuss in detail the current state of RNA interference (RNAi)-based therapies.

lncRNA TUG1 as potential novel biomarker for prognosis of cardiovascular diseases

Globally, cardiovascular diseases (CVDs) are among the leading causes of death. In light of the high prevalence and mortality of CVDs, it is imperative to understand the molecules involved in CVD pathogenesis and the signaling pathways that they initiate. This may facilitate the development of more precise and expedient diagnostic techniques, the identification of more effective prognostic molecules and the identification of potential therapeutic targets. Numerous studies have examined the role of lncRNAs, such as TUG1, in CVD pathogenesis in recent years. According to this review article, TUG1 can be considered a biomarker for predicting the prognosis of CVD.

The potential links between human gut microbiota and cardiovascular health and disease - is there a gut-cardiovascular axis?

The gut-heart axis is an emerging concept highlighting the crucial link between gut microbiota and cardiovascular diseases (CVDs). Recent studies have demonstrated that gut microbiota is pivotal in regulating host metabolism, inflammation, and immune function, critical drivers of CVD pathophysiology. Despite a strong link between gut microbiota and CVDs, this ecosystem’s complexity still needs to be fully understood. The short-chain fatty acids, trimethylamine N-oxide, bile acids, and polyamines are directly or indirectly involved in the development and prognosis of CVDs. This review explores the relationship between gut microbiota metabolites and CVDs, focusing on atherosclerosis and hypertension, and analyzes personalized microbiota-based modulation interventions, such as physical activity, diet, probiotics, prebiotics, and fecal microbiota transplantation, as a promising strategy for CVD prevention and treatment.

Immune landscape and regulatory mechanisms in human atherosclerotic coronary plaques: Evidence from single-cell and bulk transcriptomics

Atherosclerosis is a chronic immuno-inflammatory disease, however, the immune landscape and regulatory mechanisms have not been clear. We detected seven principal immune cell clusters with distinct phenotypic and spatial characteristics using single-cell RNA-sequencing of aortic immune cells from patients with acute coronary syndrome and stable angina pectoris. Then we acquired 265 differentially expressed immune-related genes and the high scores were mainly found in T cells and monocytes, which were differentially regulated in atherosclerotic coronary plaques. The CCL signaling pathway was the most relevant pattern in the T cells and CCL5-CCR1 and CCL5-CCR5 ligand-receptor pairs played a vital role in the CCL signaling pathway. Further comparative analysis indicated MCH-I signaling was the most relevant pattern in the T cells and HLA ligand-related ligand-receptor pairs played a vital role. Functional analysis of the single-cell and bulk transcriptomics pointed to multiple pathways, such as antigen presentation and immune response. Nineteen common differentially expressed immune-related genes were found in both immune cells and the human peripheral blood mononuclear cells. Nine common differentially expressed transcription factors were differentially expressed in both T cell and monocyte clusters from the coronary plaques and human peripheral blood mononuclear cells and the network demonstrated that CEBPB might play an essential role in the transcriptional regulation of atherosclerosis as a hub transcription factor. The definition of immune cell diversity and heterogeneity by single-cell level analysis of aortic immune cell subsets not only unveils cell-type-specific pathways and new immune mechanisms but also discovers the functional correlation of immune cells in human atherosclerosis. Our findings provide great promise for the discovery of novel molecular mechanisms and precise therapeutic targets for atherosclerosis.

Membrane contact sites orchestrate cholesterol homeostasis that is central to vascular aging

Chronological age causes structural and functional vascular deterioration and is a well-established risk factor for the development of cardiovascular diseases, leading to more than 40% of all deaths in the elderly. The etiology of vascular aging is complex; a significant impact arises from impaired cholesterol homeostasis. Cholesterol level is balanced through synthesis, uptake, transport, and esterification, the processes executed by multiple organelles. Moreover, organelles responsible for cholesterol homeostasis are spatially and functionally coordinated instead of isolated by forming the membrane contact sites. Membrane contact, mediated by specific protein-protein interaction, pulls opposing organelles together and creates the hybrid place for cholesterol transfer and further signaling. The membrane contact-dependent cholesterol transfer, together with the vesicular transport, maintains cholesterol homeostasis and has intimate implications in a growing list of diseases, including vascular aging-related diseases. Here, we summarized the latest advances regarding cholesterol homeostasis by highlighting the membrane contact-based regulatory mechanism. We also describe the downstream signaling under cholesterol homeostasis perturbations, prominently in cholesterol-rich conditions, stimulating age-dependent organelle dysfunction and vascular aging. Finally, we discuss potential cholesterol-targeting strategies for therapists regarding vascular aging-related diseases. This article is categorized under: Cardiovascular Diseases > Molecular and Cellular Physiology.

Proteomics Studies Suggest That Nitric Oxide Donor Furoxans Inhibit In Vitro Vascular Smooth Muscle Cell Proliferation by Nitric Oxide-Independent Mechanisms

Physiologically, smooth muscle cells (SMC) and nitric oxide (NO) produced by endothelial cells strictly cooperate to maintain vasal homeostasis. In atherosclerosis, where this equilibrium is altered, molecules providing exogenous NO and able to inhibit SMC proliferation may represent valuable antiatherosclerotic agents. Searching for dual antiproliferative and NO-donor molecules, we found that furoxans significantly decreased SMC proliferation in vitro, albeit with different potencies. We therefore assessed whether this property is dependent on their thiol-induced ring opening. Indeed, while furazans (analogues unable to release NO) are not effective, furoxans' inhibitory potency parallels with the electron-attractor capacity of the group in 3 of the ring, making this effect tunable. To demonstrate whether their specific block on G1-S phase could be NO-dependent, we supplemented SMCs with furoxans and inhibitors of GMP- and/or of the polyamine pathway, which regulate NO-induced SMC proliferation, but they failed in preventing the antiproliferative effect. To find the real mechanism of this property, our proteomics studies revealed that eleven cellular proteins (with SUMO1 being central) and networks involved in cell homeostasis/proliferation are modulated by furoxans, probably by interaction with adducts generated after degradation. Altogether, thanks to their dual effect and pharmacological flexibility, furoxans may be evaluated in the future as antiatherosclerotic molecules.

A systematic review of the impact of Porphyromonas gingivalis on foam cell formation: Implications for the role of periodontitis in atherosclerosis

BACKGROUND

The current literature suggests the significant role of foam cells in the initiation of atherosclerosis through the formation of a necrotic core in atherosclerotic plaques. Moreover, an important periodontal pathogen called Porphyromonas gingivalis (P. gingivalis) is indicated to play a significant role in this regard. Thus, the aim of this systematic review was to comprehensively study the pathways by which P. gingivalis as a prominent bacterial species in periodontal disease, can induce foam cells that would initiate the process of atherosclerosis formation.

METHODS

An electronic search was undertaken in three databases (Pubmed, Scopus, and Web of Science) to identify the studies published from January 2000 until March 2023. The risk of bias in each study was also assessed using the QUIN risk of bias assessment tool.

RESULTS

After the completion of the screening process, 11 in-vitro studies met the inclusion criteria and were included for further assessments. Nine of these studies represented a medium risk of bias, while the other two had a high risk of bias. All of the studies have reported that P. gingivalis can significantly induce foam cell formation by infecting the macrophages and induction of oxidized low-density lipoprotein (oxLDL) uptake. This process is activated through various mediators and pathways. The most important factors in this regard are the lipopolysaccharide of P. gingivalis and its outer membrane vesicles, as well as the changes in the expression rate of transmembrane lipid transportation channels, including transient receptor potential channel of the vanilloid subfamily 4 (TRPV4), lysosomal integral protein 2 (LIMP2), CD36, etc. The identified molecular pathways involved in this process include but are not limited to NF-κB, ERK1/2, p65.

CONCLUSION

Based on the results of this study, it can be concluded that P. gingivalis can effectively promote foam cell formation through various pathogenic elements and this bacterial species can affect the expression rate of various genes and the function of specific receptors in the cellular and lysosomal membranes. However, due to the moderate to high level of risk of bias among the studies, further studies are required in this regard.

Lipid-laden foam cells in the pathology of atherosclerosis: shedding light on new therapeutic targets

INTRODUCTION

Lipid-laden foam cells within atherosclerotic plaques are key players in all phases of lesion development including its progression, necrotic core formation, fibrous cap thinning, and eventually plaque rupture. Manipulating foam cell biology is thus an attractive therapeutic strategy at early, middle, and even late stages of atherosclerosis. Traditional therapies have focused on prevention, especially lowering plasma lipid levels. Despite these interventions, atherosclerosis remains a major cause of cardiovascular disease, responsible for the largest numbers of death worldwide.

AREAS COVERED

Foam cells within atherosclerotic plaques are comprised of macrophages, vascular smooth muscle cells, and other cell types which are exposed to high concentrations of lipoproteins accumulating within the subendothelial intimal layer. Macrophage-derived foam cells are particularly well studied and have provided important insights into lipid metabolism and atherogenesis. The contributions of foam cell-based processes are discussed with an emphasis on areas of therapeutic potential and directions for drug development.

EXERT OPINION

As key players in atherosclerosis, foam cells are attractive targets for developing more specific, targeted therapies aimed at resolving atherosclerotic plaques. Recent advances in our understanding of lipid handling within these cells provide insights into how they might be manipulated and clinically translated to better treat atherosclerosis.

Mulberry extract upregulates cholesterol efflux and inhibits p38 MAPK-NLRP3-mediated inflammation in foam cells

The accumulation of foam cells in arterial intima and the accompanied chronic inflammation are considered major causes of neoatherosclerosis and restenosis. However, both the underlying mechanism and effective treatment for the disease are yet to be uncovered. In this study, we combined transcriptome profiling of restenosis artery tissue and bioinformatic analysis to reveal that NLRP3 inflammasome is markedly upregulated in restenosis and that several restenosis-related DEGs are also targets of mulberry extract, a natural dietary supplement used in traditional Chinese medicine. We demonstrated that mulberry extract suppresses the formation of ox-LDL-induced foam cells, possibly by upregulating the cholesterol efflux genes ABCA1 and ABCG1 to inhibit intracellular lipid accumulation. In addition, mulberry extract dampens NLRP3 inflammasome activation by stressing the MAPK signaling pathway. These findings unveil the therapeutic value of mulberry extract in neoatherosclerosis and restenosis treatment by regulating lipid metabolism and inflammatory response of foam cells.

Hydrogen Sulfide and Oxygen Homeostasis in Atherosclerosis: A Systematic Review from Molecular Biology to Therapeutic Perspectives

Atherosclerosis is a complex pathological condition marked by the accumulation of lipids in the arterial wall, leading to the development of plaques that can eventually rupture and cause thrombotic events. In recent years, hydrogen sulfide (H₂S) has emerged as a key mediator of cardiovascular homeostasis, with potential therapeutic applications in atherosclerosis. This systematic review highlights the importance of understanding the complex interplay between H₂S, oxygen homeostasis, and atherosclerosis and suggests that targeting H₂S signaling pathways may offer new avenues for treating and preventing this condition. Oxygen homeostasis is a critical aspect of cardiovascular health, and disruption of this balance can contribute to the development and progression of atherosclerosis. Recent studies have demonstrated that H₂S plays an important role in maintaining oxygen homeostasis by regulating the function of oxygen-sensing enzymes and transcription factors in vascular cells. H₂S has been shown to modulate endothelial nitric oxide synthase (eNOS) activity, which plays a key role in regulating vascular tone and oxygen delivery to tissues. The comprehensive analysis of the current understanding of H₂S in atherosclerosis can pave the way for future research and the development of new therapeutic strategies for this debilitating condition. PROSPERO ID: 417150.

Evolving concepts in the pathophysiology of atherosclerosis: from endothelial dysfunction to thrombus formation through multiple shades of inflammation

Atherosclerosis is the anatomo-pathological substrate of most cardio, cerebro and vascular diseases such as acute and chronic coronary syndromes, stroke and peripheral artery diseases. The pathophysiology of atherosclerotic plaque and its complications are under continuous investigation. In the last 2 decades our understanding on the formation, progression and complication of the atherosclerotic lesion has greatly improved and the role of immunity and inflammation is now well documented and accepted. The conventional risk factors modulate endothelial function determining the switch to a proatherosclerotic phenotype. From this point, lipid accumulation with an imbalance from cholesterol influx and efflux, foam cells formation, T-cell activation, cytokines release and matrix-degrading enzymes production occur. Lesions with high inflammatory rate become vulnerable and prone to rupture. Once complicated, the intraplaque thrombogenic material, such as the tissue factor, is exposed to the flowing blood, thus inducing coagulation cascade activation, platelets aggregation and finally intravascular thrombus formation that leads to clinical manifestations of this disease. Nonconventional risk factors, such as gut microbiome, are emerging novel markers of atherosclerosis. Several data indicate that gut microbiota may play a causative role in formation, progression and complication of atherosclerotic lesions. The gut dysbiosis-related inflammation and gut microbiota-derived metabolites have been proposed as the main working hypothesis in contributing to disease formation and progression. The current evidence suggest that the conventional and nonconventional risk factors may modulate the degree of inflammation of the atherosclerotic lesion, thus influencing its final fate. Based on this hypothesis, targeting inflammation seems to be a promising approach to further improve our management of atherosclerotic-related diseases.

Anti-oxidant response of lipidom modulates lipid metabolism in Caenorhabditis elegans and in OxLDL-induced human macrophages by tuning inflammatory mediators

Atherosclerosis is the main pathological process of several cardiovascular diseases. It may begin early in life and stay latent and asymptomatic for an extended period before its clinical manifestation. The formation of foamy macrophages due to dysregulated lipid metabolism is a key event in the development and progression of atherosclerotic plaque. The current pharmacotherapy for atherosclerosis is not able to address multiple aetiologies associated with the disease. Lipidom, an herbal prescription medicine, has anti-oxidant, lipid lowering and anti-inflammatory properties that lead to multifaceted treatment benefits against chronic inflammation, dyslipidaemia, and oxidative stress. The present study aimed to characterize the pharmacological effects of Lipidom using various experimental models. The phytochemical analysis of Lipidom was performed on ultra-high performance liquid chromatography (UHPLC) platform. Lipidom was evaluated for cytosafety, IL-1β and MCP-1 release, modulation of NLRP3 pathway, NFκB activity, ROS generation, lipid accumulation and gene expression in THP1 macrophages. Furthermore, Lipidom evaluation was also performed in the N2, CF1553, and TJ356 strains of Caenorhabditis elegans (C. elegans). The evaluation of brood size, adult (%), lipid accumulation, triglyceride levels, SOD-3 GFP signal, MDA formation, DAF-16 nuclear translocation, and gene expression was performed in C. elegans. Lipidom treatment significantly reduced the inflammatory mediators, lipid accumulation, oxidative stress, and normalized genes involved in the development of foamy macrophages. Lipidom treated C. elegans showed a significant decline in lipid accumulation and oxidative stress. Taken together, Lipidom treatment showed a multifaceted approach in the modulation of several mediators responsible for the development and progression of atherosclerotic plaque.

Molecularly targeted nanomedicine enabled by inorganic nanoparticles for atherosclerosis diagnosis and treatment

Atherosclerosis, a chronic cardiovascular disease caused by plaque development in arteries, remains a leading cause of morbidity and mortality. Atherosclerotic plaques are characterized by the expression and regulation of key molecules such as cell surface receptors, cytokines, and signaling pathway proteins, potentially facilitating precise diagnosis and treatment on a molecular level by specifically targeting the characteristic molecules. In this review, we highlight the recent progress in the past five years on developing molecularly targeted nanomedicine for imaging detection and treatment of atherosclerosis with the use of inorganic nanoparticles. Through targeted delivery of imaging contrast nanoparticles to specific molecules in atherogenesis, atherosclerotic plaque development at different stages could be identified and monitored via various molecular imaging modalities. We also review molecularly targeted therapeutic approaches that target and regulate molecules associated with lipid regulation, inflammation, and apoptosis. The review is concluded with discussion on current challenges and future development of nanomedicine for atherosclerotic diagnosis and treatment.

Astaxanthin Alleviates Foam Cell Formation and Promotes Cholesterol Efflux in Ox-LDL-Induced RAW264.7 Cells via CircTPP2/miR-3073b-5p/ABCA1 Pathway

Atherosclerosis (AS) is a common cardiovascular disease and remains the leading cause of death in the world. It is generally believed that the deposition of foam cells in the arterial wall is the main cause of AS. Moreover, promoting cholesterol efflux and enhancing the ability of reverse cholesterol transport (RCT) can effectively inhibit the formation of foam cells, thereby preventing the occurrence and development of AS. Astaxanthin, with a powerful antioxidant ability, has a potential role in the prevention of atherosclerosis, but how it works in preventing atherosclerosis remains unknown. Here, our experimental results suggest that astaxanthin can upregulate the expression of circular RNA tripeptidyl-peptidase II (circTPP2) and eventually promote cholesterol efflux by modulating ATP-binding cassette subfamily A member 1 (ABCA1). The expression of ABCA1 was significantly suppressed after knocking down circTPP2 in macrophage-derived foam cells. In addition, the experimental results showed that circTPP2 could downregulate the expression of microRNA-3073b-5p (miR-3073b-5p), and ABCA1 was identified as the target gene of miR-3073b-5p. In conclusion, the circTPP2/miR-3073b-5p/ABCA1 axis may be the specific mechanism of astaxanthin promoting cholesterol efflux.

Hydroxytyrosol Reduces Foam Cell Formation and Endothelial Inflammation Regulating the PPARγ/LXRα/ABCA1 Pathway

Cholesterol accumulation in macrophages leads to the formation of foam cells and increases the risk of developing atherosclerosis. We have verified whether hydroxytyrosol (HT), a phenolic compound with anti-inflammatory and antioxidant properties, can reduce the cholesterol build up in THP-1 macrophage-derived foam cells. We have also investigated the potential mechanisms. Oil Red O staining and high-performance liquid chromatography (HPLC) assays were utilized to detect cellular lipid accumulation and cholesterol content, respectively, in THP-1 macrophages foam cells treated with HT. The impact of HT on cholesterol metabolism-related molecules (SR-A1, CD36, LOX-1, ABCA1, ABCG1, PPARγ and LRX-α) in foam cells was assessed using real-time PCR (RT-qPCR) and Western blot analyses. Finally, the effect of HT on the adhesion of THP-1 monocytes to human vascular endothelial cells (HUVEC) was analyzed to study endothelial activation. We found that HT activates the PPARγ/LXRα pathway to upregulate ABCA1 expression, reducing cholesterol accumulation in foam cells. Moreover, HT significantly inhibited monocyte adhesion and reduced the levels of adhesion factors (ICAM-1 and VCAM-1) and pro-inflammatory factors (IL-6 and TNF-α) in LPS-induced endothelial cells. Taken together, our findings suggest that HT, with its ability to interfere with the import and export of cholesterol, could represent a new therapeutic strategy for the treatment of atherosclerotic disease.

Regulation of ABCA1 by miR-33 and miR-34a in the Aging Eye

Many age-related diseases, including age-related macular degeneration (AMD), go along with local lipid accumulation and dysregulated lipid metabolism. Several genes involved in lipid metabolism, including ATP-binding cassette transporter A1 (ABCA1), were associated with AMD through genome-wide association studies. Recent studies have shown that loss of ABCA1 in the retinal pigment epithelium (RPE) leads to lipid accumulation and RPE atrophy, a hallmark of AMD, and that antagonizing ABCA1-targeting microRNAs (miRNAs) attenuated pathological changes to the RPE or to macrophages. Here, we focus on two lipid metabolism-modulating miRNAs, miR-33 and miR-34a, which show increased expression in aging RPE cells, and on their potential to regulate ABCA1 levels, cholesterol efflux, and lipid accumulation in AMD pathogenesis.

In silico and in vitro analysis of microRNAs with therapeutic potential in atherosclerosis

Atherosclerosis is a chronic inflammatory disease in which aberrant lipid metabolism plays a key role. MicroRNAs (miRNAs), micro-coordinators of gene expression, have been recently proposed as novel clinical biomarkers and potential therapeutic tools for a broad spectrum of diseases. This study aimed to identify miRNAs with therapeutic potential in atherosclerosis. Bioinformatic databases, including experimentally validated and computational prediction tools as well as a novel combination method, were used to identify miRNAs that are able to simultaneously inhibit key genes related to the pathogenesis of atherosclerosis. Further validation of genes and miRNAs was conducted using the STRING online tool, KEGG pathway analysis and DIANA-miRPath. The inhibitory effects of the identified miRNAs in HepG2 and Huh7 cells were verified by real-time PCR. The MTT assay was utilized to evaluate cell cytotoxicity effects of miRNAs. Atherosclerotic drug-targeted genes were selected as key genes. Strong interactions between genes were confirmed using STRING. These genes were shown to be integral to critical pathological processes involved in atherosclerosis. A novel combined method of validated and predicted tools for the identification of effective miRNAs was defined as the combination score (C-Score). Bioinformatic analysis showed that hsa-miR-124-3p and hsa-miR-16-5p possessed the best C-Score (0.68 and 0.62, respectively). KEGG and DIANA-miRPath analysis showed that selected genes and identified miRNAs were involved in atherosclerosis-related pathways. Compared with the controls in both HepG2 and Huh7 cell lines, miR-124 significantly reduced the expression of CETP, PCSK9, MTTP, and APOB, and miR-16 significantly reduced the expression of APOCIII, CETP, HMGCR, PCSK9, MTTP, and APOB, respectively. The cytotoxicity assay showed that miR-124 reduced cell viability, especially after 72 h; however, miR-16 did not show any significant cytotoxicity in either cell line. Our findings indicate that hsa-miR-124 and miR-16 have potential for use as therapeutic candidates in the treatment of atherosclerosis.

Roles and mechanisms of garlic and its extracts on atherosclerosis: A review

The prevention and treatment of cardiovascular diseases (CVDs) have achieved initial results, but the number of CVDs patients will increase rapidly in the next 10 years. Atherosclerosis (AS) is a significant risk factor for CVDs. The impact of lifestyle and daily diet varies considerably between different countries and continents and has been shown to affect the development of various diseases such as diabetes and CVDs. Primary and secondary prevention using alternative supplements and methods to avoid or reduce the use of traditional pharmacological drugs have also become popular. One of the reasons for this is that pharmacological drugs with lipid-lowering, and blood pressure-lowering effects cause many side effects that may negatively impact the quality of life. Patients are now emphasizing reliance on lifestyle changes to reduce cardiovascular risks. Garlic is a medicinal and edible plant that has been used for a long time. In order to reveal garlic application in the prevention and treatment of AS, reviewing the latest domestic and international studies through searching databases. The result shows that the antiatherogenic role of garlic is eximious. And the mechanisms are mainly related to hypolipidemic, antioxidant, antithrombotic, inhibiting angiogenesis, protecting endothelial cells, anti-inflammatory, anti-apoptotic, inhibiting vascular smooth muscle proliferation, and regulating gut microbiota. The main signaling pathways involve AMPK/TLRs, Keap1/Nrf2, PI3K/AKT, PPARγ/LXRα, GEF-H1/RhoA/Rac, etc. The antiatherogenic actions and molecular mechanism of garlic were reviewed in this study to obtain a robust evidence basis for the clinical application and mechanistic study and provide a theoretical basis for further utilization of garlic.

Intratracheal Administration of Acyl Coenzyme A Acyltransferase-1 Inhibitor K-604 Reduces Pulmonary Inflammation Following Bleomycin-Induced Lung Injury

Acute lung injury (ALI) is characterized by epithelial damage, barrier dysfunction, and pulmonary edema. Macrophage activation and failure to resolve play a role in ALI; thus, macrophage phenotype modulation is a rational target for therapeutic intervention. Large, lipid-laden macrophages have been observed in various injury models, including intratracheal bleomycin (ITB), suggesting that lipid storage may play a role in ALI severity. The endoplasmic reticulum-associated enzyme acyl coenzyme A acyltransferase-1 (Acat-1/Soat1) is highly expressed in macrophages, where it catalyzes the esterification of cholesterol, leading to intracellular lipid accumulation. We hypothesize that inhibition of Acat-1 will reduce macrophage activation and improve outcomes of lung injury in ITB. K-604, a selective inhibitor of Acat-1, was used to reduce cholesterol esterification and hence lipid accumulation in response to ITB. Male and female C57BL6/J mice (n = 16-21/group) were administered control, control + K-604, ITB, or ITB + K-604 on d0, control or K-604 on d3, and were sacrificed on day 7. ITB caused significant body weight loss and an increase in cholesterol accumulation in bronchoalveolar lavage cells. These changes were mitigated by Acat-1 inhibition. K-604 also significantly reduced ITB-induced alveolar thickening. Surfactant composition was normalized as indicated by a significant decrease in phospholipid: SP-B ratio in ITB+K-604 compared with ITB. K-604 administration preserved mature alveolar macrophages, decreased activation in response to ITB, and decreased the percentage mature and pro-fibrotic interstitial macrophages. These results show that inhibition of Acat-1 in the lung is associated with reduced inflammatory response to ITB-mediated lung injury. SIGNIFICANCE STATEMENT: Acyl coenzyme A acyltransferase-1 (Acat-1) is critical to lipid droplet formation, and thus inhibition of Acat-1 presents as a pharmacological target. Intratracheal administration of K-604, an Acat-1 inhibitor, reduces intracellular cholesterol ester accumulation in lung macrophages, attenuates inflammation and macrophage activation, and normalizes mediators of surface-active function after intratracheal bleomycin administration in a rodent model. The data presented within suggest that inhibition of Acat-1 in the lung improves acute lung injury outcomes.

PLK1 promotes cholesterol efflux and alleviates atherosclerosis by up-regulating ABCA1 and ABCG1 expression via the AMPK/PPARγ/LXRα pathway

Polo-like kinase 1 (PLK1) is a serine/threonine kinase involving lipid metabolism and cardiovascular disease. However, its role in atherogenesis has yet to be determined. The aim of this study was to observe the impact of PLK1 on macrophage lipid accumulation and atherosclerosis development and to explore the underlying mechanisms. We found a significant reduction of PLK1 expression in lipid-loaded macrophages and atherosclerosis model mice. Lentivirus-mediated overexpression of PLK1 promoted cholesterol efflux and inhibited lipid accumulation in THP-1 macrophage-derived foam cells. Mechanistic analysis revealed that PLK1 stimulated the phosphorylation of AMP-activated protein kinase (AMPK), leading to activation of the peroxisome proliferator-activated receptor γ (PPARγ)/liver X receptor α (LXRα) pathway and up-regulation of ATP binding cassette transporter A1 (ABCA1) and ABCG1 expression. Injection of lentiviral vector expressing PLK1 increased reverse cholesterol transport, improved plasma lipid profiles and decreased atherosclerotic lesion area in apoE-deficient mice fed a Western diet. PLK1 overexpression also facilitated AMPK and HSL phosphorylation and enhanced the expression of PPARγ, LXRα, ABCA1, ABCG1 and LPL in the aorta. In summary, these data suggest that PLK1 inhibits macrophage lipid accumulation and mitigates atherosclerosis by promoting ABCA1- and ABCG1-dependent cholesterol efflux via the AMPK/PPARγ/LXRα pathway.

Methotrexate effects on adenosine receptor expression in peripheral monocytes of persons with type 2 diabetes and cardiovascular disease

The Cardiovascular Inflammation Reduction Trial (CIRT) was designed to assess whether low-dose methotrexate (LD-MTX) would reduce future cardiac events in patients with metabolic syndrome or type 2 diabetes (T2DM) who are post-myocardial infarction (MI) or have multivessel disease. Our previous work indicates that MTX confers atheroprotection via adenosine A2A receptor (A2AR) activation. In order for A2AR ligation to reduce cardiovascular events, A2AR levels would need to be preserved during MTX treatment. This study was conducted to determine whether LD-MTX alters peripheral blood mononuclear cell (PBMC) adenosine receptor expression in persons at risk for cardiovascular events. Post-MI T2DM CIRT patients were randomized to LD-MTX or placebo (n=10/group). PBMC isolated from blood drawn at enrollment and after 6 weeks were evaluated for expression of adenosine receptors and reverse cholesterol transporters by real-time PCR. Fold change between time points was calculated using factorial analyses of variance. Compared with placebo, the LD-MTX group exhibited a trend toward an increase in A2AR (p=0.06), while A3R expression was significantly decreased (p=0.01) after 6 weeks. Cholesterol efflux gene expression did not change significantly. Persistence of A2AR combined with A3R downregulation indicates that failure of MTX to be atheroprotective in CIRT was not due to loss of adenosine receptors on PBMC (ClinicalTrials.gov identifier: NCT01594333).

Foam Cells in Atherosclerosis: Novel Insights Into Its Origins, Consequences, and Molecular Mechanisms

Foam cells play a vital role in the initiation and development of atherosclerosis. This review aims to summarize the novel insights into the origins, consequences, and molecular mechanisms of foam cells in atherosclerotic plaques. Foam cells are originated from monocytes as well as from vascular smooth muscle cells (VSMC), stem/progenitor cells, and endothelium cells. Novel technologies including lineage tracing and single-cell RNA sequencing (scRNA-seq) have revolutionized our understanding of subtypes of monocyte- and VSMC-derived foam cells. By using scRNA-seq, three main clusters including resident-like, inflammatory, and triggering receptor expressed on myeloid cells-2 (Trem2 hi ) are identified as the major subtypes of monocyte-derived foam cells in atherosclerotic plaques. Foam cells undergo diverse pathways of programmed cell death including apoptosis, autophagy, necroptosis, and pyroptosis, contributing to the necrotic cores of atherosclerotic plaques. The formation of foam cells is affected by cholesterol uptake, efflux, and esterification. Novel mechanisms including nuclear receptors, non-coding RNAs, and gut microbiota have been discovered and investigated. Although the heterogeneity of monocytes and the complexity of non-coding RNAs make obstacles for targeting foam cells, further in-depth research and therapeutic exploration are needed for the better management of atherosclerosis.

Perivascular adipose-derived exosomes reduce macrophage foam cell formation through miR-382-5p and the BMP4-PPARγ-ABCA1/ABCG1 pathways

Background Perivascular adipose tissue (PVAT) releases exosomes (EXOs) to regulate vascular homeostasis. PVAT-derived EXOs reduce macrophage foam cell formation, but the underlying molecular mechanism has yet to be fully elucidated. We hypothesize that PVAT release miRNA through EXOs and regulate the expression of cholesterol transporter of macrophages, thereby reducing foam cell formation. Methods and results Through RT-qPCR, we identified that miR-382-5p, which was expressed at lower levels in PVAT-EXOs from coronary atherosclerotic heart disease patients than healthy individuals, was expressed at higher levels in wild-type C57BL/6 J mouse aortic PVAT-EXOs than in subcutaneous adipose tissue-derived EXOs. We explored macrophage lipid accumulation through oil red O staining, assessed cholesterol uptake and efflux, and verified cholesterol transporter expression. We found that transfection with a miR-382-5p inhibitor offset PVAT-EXO-related reductions in macrophage foam cell formation and increases in cholesterol efflux mediated by ATP-binding cassette transporter A1 (ABCA1) and ATP-binding cassette transporter G1 (ABGA1). In addition, bone morphogenetic protein 4 (BMP4) pretreatment and si-peroxisome proliferator-activated receptor γ (PPARγ) transfection showed that BMP4-PPARγ participated in PVAT-EXO-mediated upregulation of the cholesterol efflux transporters ABCA1 and ABCG1. Conclusions PVAT-EXOs reduce macrophage foam cell formation through miR-382-5p- and BMP4-PPARγ-mediated upregulation of the cholesterol efflux transporters ABCA1 and ABCG1. This finding suggests a promising strategy for the prevention and treatment of atherosclerosis.

Inflammatory Cells in Atherosclerosis

Atherosclerosis is a chronic progressive disease that involves damage to the intima, inflammatory cell recruitment and the accumulation of lipids followed by calcification and plaque rupture. Inflammation is considered a key mediator of many events during the development and progression of the disease. Various types of inflammatory cells are reported to be involved in atherosclerosis. In the present paper, we discuss the involved inflammatory cells, their characteristic and functional significance in the development and progression of atherosclerosis. The detailed understanding of the role of all these cells in disease progression at different stages sheds more light on the subject and provides valuable insights as to where and when therapy should be targeted.

Cholesterol in the Cell Membrane-An Emerging Player in Atherogenesis

Membrane cholesterol is essential for cell membrane properties, just as serum cholesterol is important for the transport of molecules between organs. This review focuses on cholesterol transport between lipoproteins and lipid rafts on the surface of macrophages. Recent studies exploring this mechanism and recognition of the central dogma-the key role of macrophages in cardiovascular disease-have led to the notion that this transport mechanism plays a major role in the pathogenesis of atherosclerosis. The exact molecular mechanism of this transport remains unclear. Future research will improve our understanding of the molecular and cellular bases of lipid raft-associated cholesterol transport.

Flow Cytometry Analysis of Hematopoietic Stem/Progenitor Cells and Mature Blood Cell Subsets in Atherosclerosis

Advancing age causes physiologic decline in tissue function. In the hematopoietic system this manifests as a progressive reduction in blood or immune cell function and clonal hematopoiesis, where a mutated hematopoietic stem cell can dominate blood cell production and confer an increased propensity for myeloid malignancy. In the aging cardiovascular system, atherosclerosis causes an inflammatory cell- driven accumulation of lipid-derived plaques in major arteries which constrains blood flow and can lead to myocardial infarction and stroke. Clonal hematopoiesis in the elderly has recently been associated with a substantially increased risk of atherosclerosis-related cardiovascular disease. However, the direct association between deregulated hematopoiesis in clonal hematopoiesis and atherosclerosis is poorly defined. Herein, we describe a flow cytometry method to prospectively analyze the crucial hematopoietic stem/progenitor, inflammatory and lymphoid cell participants in atherosclerosis. This analysis can be applied to decipher the complex relationship between hematopoietic cell types involved in clonal hematopoiesis and atherosclerosis in mouse models.

The Role of p66Shc in Diabetes: A Comprehensive Review from Bench to Bedside

It is well-documented that diabetes is an inflammatory and oxidative disease, with an escalating global burden. Still, there is no definite treatment for diabetes or even prevention of its harmful complications. Therefore, understanding the molecular pathways associated with diabetes might help in finding a solution. p66Shc is a member of Shc family proteins, and it is considered as an oxidative stress sensor and regulator in cells. There are inconsistent data about the role of p66Shc in inducing diabetes, but accumulating evidence supports its role in the pathogenesis of diabetes-related complications, including macro and microangiopathies. There is growing hope that by understanding and targeting molecular pathways involved in this network, prevention of diabetes or its complications would be achievable. This review provides an overview about the role of p66Shc in the development of diabetes and its complications.

Genomic Variants and Multilevel Regulation of ABCA1, ABCG1, and SCARB1 Expression in Atherogenesis

Atheroprotective properties of human plasma high-density lipoproteins (HDLs) are determined by their involvement in reverse cholesterol transport (RCT) from the macrophage to the liver. ABCA1, ABCG1, and SR-BI cholesterol transporters are involved in cholesterol efflux from macrophages to lipid-free ApoA-I and HDL as a first RCT step. Molecular determinants of RCT efficiency that may possess diagnostic and therapeutic meaning remain largely unknown. This review summarizes the progress in studying the genomic variants of ABCA1, ABCG1, and SCARB1, and the regulation of their function at transcriptional and post-transcriptional levels in atherosclerosis. Defects in the structure and function of ABCA1, ABCG1, and SR-BI are caused by changes in the gene sequence, such as single nucleotide polymorphism or various mutations. In the transcription initiation of transporter genes, in addition to transcription factors, long noncoding RNA (lncRNA), transcription activators, and repressors are also involved. Furthermore, transcription is substantially influenced by the methylation of gene promoter regions. Post-transcriptional regulation involves microRNAs and lncRNAs, including circular RNAs. The potential biomarkers and targets for atheroprotection, based on molecular mechanisms of expression regulation for three transporter genes, are also discussed in this review.

Macrophages and Foam Cells: Brief Overview of Their Role, Linkage, and Targeting Potential in Atherosclerosis

Atherosclerosis is still one of the main causes of death around the globe. This condition leads to various life-threatening cardiovascular complications. However, no effective preventive measures are known apart from lifestyle corrections, and no cure has been developed. Despite numerous studies in the field of atherogenesis, there are still huge gaps in already poor understanding of mechanisms that underlie the disease. Inflammation and lipid metabolism violations are undoubtedly the key players, but many other factors, such as oxidative stress, endothelial dysfunction, contribute to the pathogenesis of atherosclerosis. This overview is focusing on the role of macrophages in atherogenesis, which are at the same time a part of the inflammatory response, and also tightly linked to the foam cell formation, thus taking part in both crucial for atherogenesis processes. Being essentially involved in atherosclerosis development, macrophages and foam cells have attracted attention as a promising target for therapeutic approaches.

Role of Lipid Accumulation and Inflammation in Atherosclerosis: Focus on Molecular and Cellular Mechanisms

Atherosclerosis is a chronic lipid-driven and maladaptive inflammatory disease of arterial intima. It is characterized by the dysfunction of lipid homeostasis and signaling pathways that control the inflammation. This article reviews the role of inflammation and lipid accumulation, especially low-density lipoprotein (LDL), in the pathogenesis of atherosclerosis, with more emphasis on cellular mechanisms. Furthermore, this review will briefly highlight the role of medicinal plants, long non-coding RNA (lncRNA), and microRNAs in the pathophysiology, treatment, and prevention of atherosclerosis. Lipid homeostasis at various levels, including receptor-mediated uptake, synthesis, storage, metabolism, efflux, and its impairments are important for the development of atherosclerosis. The major source of cholesterol and lipid accumulation in the arterial wall is proatherogenic modified low-density lipoprotein (mLDL). Modified lipoproteins, such as oxidized low-density lipoprotein (ox-LDL) and LDL binding with proteoglycans of the extracellular matrix in the intima of blood vessels, cause aggregation of lipoprotein particles, endothelial damage, leukocyte recruitment, foam cell formation, and inflammation. Inflammation is the key contributor to atherosclerosis and participates in all phases of atherosclerosis. Also, several studies have shown that microRNAs and lncRNAs have appeared as key regulators of several physiological and pathophysiological processes in atherosclerosis, including regulation of HDL biogenesis, cholesterol efflux, lipid metabolism, regulating of smooth muscle proliferation, and controlling of inflammation. Thus, both lipid homeostasis and the inflammatory immune response are closely linked, and their cellular and molecular pathways interact with each other.