CCL18 aggravates atherosclerosis by inducing CCR6-dependent T-cell influx and polarization

Introduction

The CC chemokine ligand 18 (CCL18) is a chemokine highly expressed in chronic inflammation in humans. Recent observations of elevated CCL18 plasma levels in patients with acute cardiovascular syndromes prompted an investigation into the role of CCL18 in the pathogenesis of human and mouse atherosclerosis.

Methods and results

CCL18 was profoundly upregulated in ruptured human atherosclerotic plaque, particularly within macrophages. Repeated administration of CCL18 in Western-type diet-fed ApoE -/- mice or PCSK9mut-overexpressing wild type (WT) mice led to increased plaque burden, enriched in CD3+ T cells. In subsequent experimental and molecular modeling studies, we identified CCR6 as a functional receptor mediating CCL18 chemotaxis, intracellular Ca2+ flux, and downstream signaling in human Jurkat and mouse T cells. CCL18 failed to induce these effects in vitro in murine spleen T cells with CCR6 deficiency. The ability of CCR6 to act as CCL18 receptor was confirmed in vivo in an inflammation model, where subcutaneous CCL18 injection induced profound focal skin inflammation in WT but not in CCR6-/- mice. This inflammation featured edema and marked infiltration of various leukocyte subsets, including T cells with a Th17 signature, supporting CCR6's role as a Th17 chemotactic receptor. Notably, focal overexpression of CCL18 in plaques was associated with an increased presence of CCR6+ (T) cells.

Discussion

Our studies are the first to identify the CCL18/CCR6 axis as a regulator of immune responses in advanced murine and human atherosclerosis.

Metabolic reprogramming of immune cells by mitochondrial division inhibitor-1 to prevent post-vascular injury neointimal hyperplasia

BACKGROUND AND AIMS

New treatments are needed to prevent neointimal hyperplasia that contributes to post-angioplasty and stent restenosis in patients with coronary artery disease (CAD) and peripheral arterial disease (PAD). We investigated whether modulating mitochondrial function using mitochondrial division inhibitor-1 (Mdivi-1) could reduce post-vascular injury neointimal hyperplasia by metabolic reprogramming of macrophages from a pro-inflammatory to anti-inflammatory phenotype.

METHODS AND RESULTS

In vivo Mdivi-1 treatment of Apoe-/- mice fed a high-fat diet and subjected to carotid-wire injury decreased neointimal hyperplasia by 68%, reduced numbers of plaque vascular smooth muscle cells and pro-inflammatory M1-like macrophages, and decreased plaque inflammation, endothelial activation, and apoptosis, when compared to control. Mdivi-1 treatment of human THP-1 macrophages shifted polarization from a pro-inflammatory M1-like to an anti-inflammatory M2-like phenotype, reduced monocyte chemotaxis and migration to CCL2 and macrophage colony stimulating factor (M-CSF) and decreased secretion of pro-inflammatory mediators. Finally, treatment of pro-inflammatory M1-type-macrophages with Mdivi-1 metabolically reprogrammed them to an anti-inflammatory M2-like phenotype by inhibiting oxidative phosphorylation and attenuating the increase in succinate levels and correcting the decreased levels of arginine and citrulline.

CONCLUSIONS

We report that treatment with Mdivi-1 inhibits post-vascular injury neointimal hyperplasia by metabolic reprogramming macrophages towards an anti-inflammatory phenotype thereby highlighting the therapeutic potential of Mdivi-1 for preventing neointimal hyperplasia and restenosis following angioplasty and stenting in CAD and PAD patients.

Knockdown of ADAMDEC1 ameliorates ox-LDL-induced endothelial cell injury and atherosclerosis progression

This study was designed to investigate the role of a disintegrin and metalloproteinase domain-like protein decysin 1 (ADAMDEC-1) in atherosclerosis (AS). The Gene Expression Omnibus (GEO) database was utilized to identify differentially expressed genes (DEGs) between carotid atheroma plaque and carotid tissue adjacent atheroma plaque obtained from AS patients. Gene functional enrichment analysis was conducted on DEGs using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). QRT-PCR was employed to quantify mRNAs expression. AS animal model was established using ApoE-/- mice; serum triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) levels were detected. Aortic sinus atherosclerotic lesions were observed using H&E staining and Oil Red O staining. ADAMDEC-1 was silenced using small interfering RNAs (siRNAs) in human vascular smooth muscle cells (HVSMCs). Cell proliferation, migration, and cell cycle progression were detected by cell count kit-8 (CCK8), 5-ethynyl-2'-deoxyuridine (EDU), wound scratch healing assay, transwell assay, and flow cytometry, respectively. Western blot was used to evaluate various protein expression levels. Our results showed that ADAMDEC-1 was highly expressed in the serum of AS patients, consistent with the in silico results. The elevated TG, LDL-C, and HDL-C levels along with H&E and Oil Red O staining confirmed the successful establishment of the AS mouse model. ADAMDEC-1 expression was also elevated in AS mice. ADAMDEC-1 knockdown in HVSMCs suppressed cell proliferation, inhibited the expression of proliferating cell nuclear antigen (PCNA), and reduced the levels of matrix metalloproteinases (MMP2 and MMP9) proteins. Protein-protein interaction (PPI) analysis indicated that ADAMDEC-1 was associated with CXCL9, CCR5, TNF-α, TNFR1, and NF-κB-p50. The expression levels of CXCL9, CCR5, TNF-α, TNFR1, and NF-κB-p50 increased, while ADAMDEC-1 knockdown attenuated the expression of these proteins. Our study findings substantiate that ADAMDEC-1 may represent a novel target for AS.

Circular RNAs Variously Participate in Coronary Atherogenesis

Over the past decade, numerous studies have shown that circular RNAs (circRNAs) play a significant role in coronary artery atherogenesis and other cardiovascular diseases. They belong to the class of non-coding RNAs and arise as a result of non-canonical splicing of premature RNA, which results in the formation of closed single-stranded circRNA molecules that lack 5'-end caps and 3'-end poly(A) tails. circRNAs have broad post-transcriptional regulatory activity. Acting as a sponge for miRNAs, circRNAs compete with mRNAs for binding to miRNAs, acting as competing endogenous RNAs. Numerous circRNAs are involved in the circRNA-miRNA-mRNA regulatory axes associated with the pathogenesis of cardiomyopathy, chronic heart failure, hypertension, atherosclerosis, and coronary artery disease. Recent studies have shown that сirc_0001445, circ_0000345, circ_0093887, сircSmoc1-2, and circ_0003423 are involved in the pathogenesis of coronary artery disease (CAD) with an atheroprotective effect, while circ_0002984, circ_0029589, circ_0124644, circ_0091822, and circ_0050486 possess a proatherogenic effect. With their high resistance to endonucleases, circRNAs are promising diagnostic biomarkers and therapeutic targets. This review aims to provide updated information on the involvement of atherogenesis-related circRNAs in the pathogenesis of CAD. We also discuss the main modern approaches to detecting and studying circRNA-miRNA-mRNA interactions, as well as the prospects for using circRNAs as biomarkers and therapeutic targets for the treatment of cardiovascular diseases.

Endothelial Gata6 deletion reduces monocyte recruitment and proinflammatory macrophage formation and attenuates atherosclerosis through Cmpk2-Nlrp3 pathways

Endothelial dysfunction results in chronic vascular inflammation, which is critical for the development of atherosclerotic diseases. Transcription factor Gata6 has been reported to regulate vascular endothelial cell activation and inflammation in vitro. Here, we aimed to explore the roles and mechanisms of endothelial Gata6 in atherogenesis. Endothelial cell (EC) specific Gata6 deletion was generated in the ApoeKO hyperlipidemic atherosclerosis mouse model. Atherosclerotic lesion formation, endothelial inflammatory signaling, and endothelial-macrophage interaction were examined in vivo and in vitro by using cellular and molecular biological approaches. EC-GATA6 deletion mice exhibited a significant decrease in monocyte infiltration and atherosclerotic lesion compared to littermate control mice. Cytosine monophosphate kinase 2 (Cmpk2) was identified as a direct target gene of GATA6 and EC-GATA6 deletion decreased monocyte adherence, migration and pro-inflammatory macrophage foam cell formation through regulation of the CMPK2-Nlrp3 pathway. Endothelial target delivery of Cmpk2-shRNA by intercellular adhesion molecule 2 (Icam-2) promoter-driven AAV9 carrying the shRNA reversed the Gata6 upregulation mediated elevated Cmpk2 expression and further Nlrp3 activation and thus attenuated atherosclerosis. In addition, C-C motif chemokine ligand 5 (Ccl5) was also identified as a direct target gene of Gata6 to regulate monocyte adherence and migration influencing atherogenesis. This study provides direct in vivo evidence of EC-GATA6 involvement in the regulation of Cmpk2-Nlrp3, as well as Ccl5, on monocyte adherence and migration in atherosclerosis development and advances our understanding of the in vivo mechanisms of atherosclerotic lesion development, and meanwhile provides opportunities for future therapeutic interventions.

Prospects for targeting ACKR1 in cancer and other diseases

The chemokine network is comprised of a family of signal proteins that encode messages for cells displaying chemokine G-protein coupled receptors (GPCRs). The diversity of effects on cellular functions, particularly directed migration of different cell types to sites of inflammation, is enabled by different combinations of chemokines activating signal transduction cascades on cells displaying a combination of receptors. These signals can contribute to autoimmune disease or be hijacked in cancer to stimulate cancer progression and metastatic migration. Thus far, three chemokine receptor-targeting drugs have been approved for clinical use: Maraviroc for HIV, Plerixafor for hematopoietic stem cell mobilization, and Mogalizumab for cutaneous T-cell lymphoma. Numerous compounds have been developed to inhibit specific chemokine GPCRs, but the complexity of the chemokine network has precluded more widespread clinical implementation, particularly as anti-neoplastic and anti-metastatic agents. Drugs that block a single signaling axis may be rendered ineffective or cause adverse reactions because each chemokine and receptor often have multiple context-specific functions. The chemokine network is tightly regulated at multiple levels, including by atypical chemokine receptors (ACKRs) that control chemokine gradients independently of G-proteins. ACKRs have numerous functions linked to chemokine immobilization, movement through and within cells, and recruitment of alternate effectors like β-arrestins. Atypical chemokine receptor 1 (ACKR1), previously known as the Duffy antigen receptor for chemokines (DARC), is a key regulator that binds chemokines involved in inflammatory responses and cancer proliferation, angiogenesis, and metastasis. Understanding more about ACKR1 in different diseases and populations may contribute to the development of therapeutic strategies targeting the chemokine network.

Vulnerable Plaque Imaging

Atherosclerotic plaques progress as a result of inflammation. Both invasive and noninvasive imaging techniques have been developed to identify and characterize plaque as vulnerable (more likely to rupture and cause a clinical event). Imaging techniques to identify vulnerable include identifying vessels with focal subendothelial collections of I) inflammatory cells; II) lipid/ fatty acid; III) local regions of hypoxia; IV) local expression of angiogenesis factors; V) local expression of protease; VI) intravascular foci of thrombus; hemorrhage (most often seen in the aftermath of a clinical event); VII) apoptosis and VIII) microcalcification. This review provides an overview of atherosclerotic plaque progression and tracers which can visualize specific molecules associated with vulnerability.

Discovery of Bis-Imidazoline Derivatives as New CXCR4 Ligands

The chemokine receptor CXCR4 and its ligand CXCL12 regulate leukocyte trafficking, homeostasis and functions and are potential therapeutic targets in many diseases such as HIV-1 infection and cancers. Here, we identified new CXCR4 ligands in the CERMN chemical library using a FRET-based high-throughput screening assay. These are bis-imidazoline compounds comprising two imidazole rings linked by an alkyl chain. The molecules displace CXCL12 binding with submicromolar potencies, similarly to AMD3100, the only marketed CXCR4 ligand. They also inhibit anti-CXCR4 mAb 12G5 binding, CXCL12-mediated chemotaxis and HIV-1 infection. Further studies with newly synthesized derivatives pointed out to a role of alkyl chain length on the bis-imidazoline properties, with molecules with an even number of carbons equal to 8, 10 or 12 being the most potent. Interestingly, these differ in the functions of CXCR4 that they influence. Site-directed mutagenesis and molecular docking predict that the alkyl chain folds in such a way that the two imidazole groups become lodged in the transmembrane binding cavity of CXCR4. Results also suggest that the alkyl chain length influences how the imidazole rings positions in the cavity. These results may provide a basis for the design of new CXCR4 antagonists targeting specific functions of the receptor.

Evolution, Expression and Functional Analysis of CXCR3 in Neuronal and Cardiovascular Diseases: A Narrative Review

Chemokines form a sophisticated communication network wherein they maneuver the spatiotemporal migration of immune cells across a system. These chemical messengers are recognized by chemokine receptors, which can trigger a cascade of reactions upon binding to its respective ligand. CXC chemokine receptor 3 (CXCR3) is a transmembrane G protein-coupled receptor, which can selectively bind to CXCL9, CXCL10, and CXCL11. CXCR3 is predominantly expressed on immune cells, including activated T lymphocytes and natural killer cells. It thus plays a crucial role in immunological processes like homing of effector cells to infection sites and for pathogen clearance. Additionally, it is expressed on several cell types of the central nervous system and cardiovascular system, due to which it has been implicated in several central nervous system disorders, including Alzheimer's disease, multiple sclerosis, dengue viral disease, and glioblastoma, as well as cardiovascular diseases like atherosclerosis, Chronic Chagas cardiomyopathy, and hypertension. This review provides a narrative description of the evolution, structure, function, and expression of CXCR3 and its corresponding ligands in mammals and zebrafish and the association of CXCR3 receptors with cardiovascular and neuronal disorders. Unraveling the mechanisms underlying the connection of CXCR3 and disease could help researchers investigate the potential of CXCR3 as a biomarker for early diagnosis and as a therapeutic target for pharmacological intervention, along with developing robust zebrafish disease models.

Cannabinoid receptor 1 antagonist genistein attenuates marijuana-induced vascular inflammation

Epidemiological studies reveal that marijuana increases the risk of cardiovascular disease (CVD); however, little is known about the mechanism. Δ⁹-tetrahydrocannabinol (Δ⁹-THC), the psychoactive component of marijuana, binds to cannabinoid receptor 1 (CB1/CNR1) in the vasculature and is implicated in CVD. A UK Biobank analysis found that cannabis was an risk factor for CVD. We found that marijuana smoking activated inflammatory cytokines implicated in CVD. In silico virtual screening identified genistein, a soybean isoflavone, as a putative CB1 antagonist. Human-induced pluripotent stem cell-derived endothelial cells were used to model Δ⁹-THC-induced inflammation and oxidative stress via NF-κB signaling. Knockdown of the CB1 receptor with siRNA, CRISPR interference, and genistein attenuated the effects of Δ⁹-THC. In mice, genistein blocked Δ⁹-THC-induced endothelial dysfunction in wire myograph, reduced atherosclerotic plaque, and had minimal penetration of the central nervous system. Genistein is a CB1 antagonist that attenuates Δ⁹-THC-induced atherosclerosis.

Inflammation, oxidative stress and altered heat shock response in type 2 diabetes: the basis for new pharmacological and non-pharmacological interventions

Type 2 diabetes mellitus (DM2) is a chronic disease characterised by variable degrees of insulin resistance and impaired insulin secretion. Besides, several pieces of evidence have shown that chronic inflammation, oxidative stress, and 70 kDa heat shock proteins (HSP70) are strongly involved in DM2 and its complications, and various pharmacological and non-pharmacological treatment alternatives act in these processes/molecules to modulate them and ameliorate the disease. Besides, uncontrolled hyperglycaemia is related to several complications as diabetic retinopathy, neuropathy and hepatic, renal and cardiac complications. In this review, we address discuss the involvement of different inflammatory and pro-oxidant pathways related to DM2, and we described molecular targets modulated by therapeutics currently available to treat DM2.

Exploring the Relationship of Perivascular Adipose Tissue Inflammation and the Development of Vascular Pathologies

Initially thought to only provide mechanical support for the underlying blood vessels, perivascular adipose tissue (PVAT) has now emerged as a regulator of vascular function. A healthy PVAT exerts anticontractile and anti-inflammatory actions on the underlying vasculature via the release of adipocytokines such as adiponectin, nitric oxide, and omentin. However, dysfunctional PVAT produces more proinflammatory adipocytokines such as leptin, resistin, interleukin- (IL-) 6, IL-1β, and tumor necrosis factor-alpha, thus inducing an inflammatory response that contributes to the pathogenesis of vascular diseases. In this review, current knowledge on the role of PVAT inflammation in the development of vascular pathologies such as atherosclerosis and hypertension was discussed.

Antagonizing the CX3CR1 Receptor Markedly Reduces Development of Cardiac Hypertrophy After Transverse Aortic Constriction in Mice

ABSTRACT

Left-ventricular hypertrophy, characterized by cardiomyocyte hypertrophy, interstitial cell proliferation, and immune cell infiltration, is a high risk factor for heart failure and death. Chemokines interacting with G protein-coupled chemokine receptors probably play a role in left-ventricular hypertrophy development by promoting recruitment of activated leukocytes and modulating left-ventricular remodeling. Using the minimally invasive model of transverse aortic constriction in mice, we demonstrated that a variety of chemokine and chemokine receptor messenger Ribonucleic Acid are overexpressed in the early and late phase of hypertrophy progression. Among the chemokine receptors, Cx3cr1 and Ccr2 were most strongly overexpressed and were significantly upregulated at 3, 7, and 14 days after transverse aortic constriction. Ligands of CX3CR1 (Cx3cl1) and CCR2 (Ccl2, Ccl7, Ccl12) were significantly overexpressed in the left ventricle at the early stages after mechanical pressure overload. Pharmacological inhibition of CX3CR1 signaling using the antagonist AZD8797 led to a significant reduction of hypertrophy, whereas inhibition of CCR2 with the RS504393 antagonist did not show any effect. Furthermore, AZD8797 treatment reduced the expression of the hypertrophic marker genes Nppa and Nppb as well as the profibrotic genes Tgfb1 and Col1a1 at 14 days after transverse aortic constriction. These findings strongly suggest the involvement of the CX3CR1/CX3CL1 pathway in the pathogenesis of left-ventricular hypertrophy.

The Effect of Homocysteine on the Secretion of Il-1β, Il-6, Il-10, Il-12 and RANTES by Peripheral Blood Mononuclear Cells-An In Vitro Study

The contemporary theory of the inflammatory-immunological pathomechanism of atherosclerosis includes the participation of interleukin-1β (Il), Il-6, Il-10, Il-12, RANTES, and homocysteine in this process. The knowledge on the direct effect of hyperhomocysteinemia on inflammatory-state-related atherosclerosis is rather scarce. Our study is the first to account for the effects of homocysteine on the secretion of Il-10 and RANTES in vitro conditions. For this purpose, human mitogen-stimulated peripheral blood mononuclear cells (PBMNCs) were cultured in vitro and exposed to homocysteine at high concentrations. Subsequently, the concentrations of cytokines were assayed in the cell culture supernatant using flow cytofluorimetry. It has been shown that, in the presence of homocysteine, the secretion of IL-1, IL-6 and RANTES by PBMNCs was increased, whereas IL-10 concentration was significantly lower than that of the supernatant derived from a mitogen-stimulated cell culture without homocysteine. The secretion of Il-12 by PBMNCs exposed exclusively to mitogen, did not differ from homologous cells also treated with homocysteine. Therefore, in our opinion, high-concentration homocysteine affects the progression of atherosclerosis by increasing the secretion of proinflammatory cytokines secreted by PBMNCs, such as Il-1β, Il-6, RANTES, and by attenuating the secretion of Il-10.

Bioinformatics analysis reveals the landscape of immune cell infiltration and immune-related pathways participating in the progression of carotid atherosclerotic plaques

Atherosclerosis is a systemic disease associated with inflammatory cell infiltration and activation of immune-related pathways. In our study, we aimed to uncover immune-related changes and explore novel immunological features in the development of carotid atherosclerotic plaques. First, we applied integrated bioinformatics methods, including CIBERSORT and gene set enrichment analysis (GSEA). The gene expression matrices GSE28829, GSE41571, and GSE43292 were obtained from the Gene Expression Omnibus (GEO) dataset. After a series of data pre-processing steps, the resulting combined expression matrices were analysed using the CIBERSORT, GSEA, and Cluster Profiler packages. After the comparison and analysis between the carotid atherosclerotic plaques in the early and advanced stages, we discovered that there is a higher percentage of activated memory CD4 T cells and a lower percentage of resting memory CD4 cells in advanced-stage plaques. Moreover, activation of memory CD4 T cells can promote the development of carotid atherosclerotic plaques. Additionally, FOXP3⁺ Treg cell maturation can also participate in the progression of carotid plaques.

Platelet Bone Morphogenetic Protein-4 Mediates Vascular Inflammation and Neointima Formation after Arterial Injury

The purpose of this study is to investigate the role of platelet bone morphogenetic proteins (BMP)-4 during vascular inflammation and remodeling in a mouse model of carotid wire injury. Transgenic mice with a platelet-specific deletion of BMP-4 (BMP4Plt-/-) were generated. Intravital microscopy was performed to evaluate leukocyte adhesion to the vessel wall. Expression of adhesion molecules and chemokines were analyzed. Platelet-leukocyte aggregates (PLAs) were evaluated using flow cytometry. For carotid wire injury, BMP4Plt-/- mice were further crossed with LDLr-/- mice (BMP4Plt-/-/LDLr-/-) and fed with a high cholesterol diet for 2-weeks. Carotid wire injury was performed, and re-endothelialization and neointimal formation were evaluated. In comparison to the control mice, stimulation with TNFα resulted in fewer rolling and adherent leukocytes to the vessel wall in the BMP4Plt-/- mice. mRNA and protein expression of P-selectin and adhesion molecules were reduced in the aorta of the BMP4Plt-/- mice. In platelets from the BMP4Plt-/- mice, the expression of P-selectin was reduced, and fewer PLA formations were measured than in the control mice. Loss of platelet BMP-4 further prevented neointima formation after carotid wire injury. Endothelial regeneration after injury was decelerated in the BMP4Plt-/- mice, and confirmed in-vitro, where the deletion of platelet BMP-4 inhibited endothelial cell proliferation and migration. We demonstrate for the first time that platelet BMP-4 is involved during vascular inflammation and remodeling. This is partially mediated by the inhibition of platelet activation, reduced expression of adhesion molecules and inflammatory responses. Our findings identify platelet BMP-4 as a mediator of vascular inflammation in early atherosclerosis and restenosis.

Immunotherapy and cardiovascular diseases (CVD): novel avenues for immunotherapeutic approaches

As current therapies for cardiovascular disease (CVD), predominantly based on lipid lowering, still face an unacceptable residual risk, novel treatment strategies are being explored. Besides lipids, inflammatory processes play a major role in the pathogenesis of atherosclerosis, the underlying cause of the majority of CVD. The first clinical trials targeting the interleukin-1β-inflammasome axis have shown that targeting this pathway is successful in reducing cardiovascular events but did not decrease overall CVD mortality. Hence, novel and improved immunotherapeutics to treat CVD are being awaited. In this review we highlight novel immunotherapeutic approaches in CVD as well as future challenges ahead.

Interleukin-36γ aggravates macrophage foam cell formation and atherosclerosis progression in ApoE knockout mice

Atherosclerosis-related cardiovascular diseases are the leading cause of mortality worldwide. Macrophage-derived foam cell formation is a critical early event in atherogenesis. However, the molecular pathways involved in this disease have not been fully elucidated. Interleukin (IL)-36 plays a crucial role in inflammation, and this study was conducted to investigate the possible role of IL-36γ in the pathogenesis and regulation of atherosclerosis. In this study, we show that IL-36γ regulates inflammatory responses and lipoprotein metabolic processes in macrophages and exerts its atherosclerosis-promoting effects by increasing macrophage foam cell formation and uptake of oxidized low-density lipoproteins. Mechanistically, IL-36γ specifically upregulates expression of the scavenger receptor CD36 through the phosphoinositide 3-kinase pathway in macrophages. These results contribute to our understanding of IL-36γ as a novel regulator of foam cell formation and atherogenesis progression.

Kakonein restores diabetes-induced endothelial junction dysfunction via promoting autophagy-mediated NLRP3 inflammasome degradation

In diabetes‐induced complications, inflammatory‐mediated endothelial dysfunction is the core of disease progression. Evidence shows that kakonein, an isoflavone common in Pueraria, can effectively treat diabetes and its complications. Therefore, we explored whether kakonein protects cardiovascular endothelial function by inhibiting inflammatory responses. In this study, C57BL/6J mice were injected with streptozocin to establish a diabetes model and treated with kakonein or metformin for 7 days. The protective effect of kakonein on cardiovascular endothelial junctions and NLRP3 inflammasome activation was verified through immunofluorescence and ELISA assay. In addition, the regulation of autophagy on the NLRP3 inflammasome was investigated through Western blot, immunofluorescence and RT‐qPCR. Results showed that kakonein restored the function of endothelial junctions and inhibited the assembly and activation of the NLRP3 inflammasome. Interestingly, kakonein decreased the expression of NLRP3 inflammasome protein by not reducing the transcriptional levels of NLRP3 and caspase‐1. Kakonein activated autophagy in an AMPK‐dependent manner, which reduced the activation of the NLRP3 inflammasome. In addition, kakonein inhibited both hyperglycaemia‐induced cardiovascular endothelial junction dysfunction and NLRP3 inflammasome activation, similar to autophagy agonist. Our findings indicated that kakonein exerts a protective effect on hyperglycaemia‐induced chronic vascular disease by regulating the NLRP3 inflammasome through autophagy.

Inflammatory Gene Expression in Neck Perivascular and Subcutaneous Adipose Tissue in Men With Carotid Stenosis

The inflammatory phenotype of neck adipose tissue (NAT) might reflect its involvement in the pathogenesis of carotid atherosclerosis. We investigated inflammatory gene expression in the subcutaneous and the perivascular (pericarotid) adipose tissue from patients with carotid stenosis (CS) undergoing endarterectomy and a control group of patients without significant carotid atherosclerosis undergoing thyroid surgery. Only male patients were included (n = 13 in each study group). Clinical and biochemical data along with serum leptin, adiponectin, and monocyte chemoattractant protein 1 (MCP-1) were collected. Adipose tissue samples were obtained from both the subcutaneous and pericarotid compartments. Real-time polymerase chain reaction was used to measure gene expression of macrophage markers and adipokines. The CS group had higher subcutaneous and pericarotid visfatin gene expression and higher pericarotid expression of MCP-1 and CD68 genes. The ratio between pericarotid CD206 and CD68 gene expression was similar between study groups. Adiponectin gene expression in both NAT compartments did not differ between groups, but it was negatively associated with body weight. These observations suggest that NAT, and especially the pericarotid compartment, express enhanced inflammatory properties in patients with CS, but the proportion of anti-inflammatory macrophages in advanced atherosclerosis seems to be maintained.

Mechanosensitive smooth muscle cell phenotypic plasticity emerging from a null state and the balance between Rac and Rho

Reversible differentiation of vascular smooth muscle cells (VSMCs) plays a critical role in vascular biology and disease. Changes in VSMC differentiation correlate with stiffness of the arterial extracellular matrix (ECM), but causal relationships remain unclear. We show that VSMC plasticity is mechanosensitive and that both the de-differentiated and differentiated fates are promoted by the same ECM stiffness. Differential equations developed to model this behavior predicted that a null VSMC state generates the dual fates in response to ECM stiffness. Direct measurements of cellular forces, proliferation, and contractile gene expression validated these predictions and showed that fate outcome is mediated by Rac-Rho homeostasis. Rac, through distinct effects on YAP and TAZ, is required for both fates. Rho drives the contractile state alone, so its level of activity, relative to Rac, drives phenotypic choice. Our results show how the cellular response to a single ECM stiffness generates bi-stability and VSMC plasticity.

Reversible differentiation/de-differentiation of smooth muscle cells plays a critical role in vascular biology and disease. Talwar et al. show that these differentiated and de-differentiated phenotypes emerge from a null state that is regulated by ECM stiffness and bidirectional effects of Rac on YAP and TAZ transcriptional coregulators.

CXCR4-Binding Positron Emission Tomography Tracers Link Monocyte Recruitment and Endothelial Injury in Murine Atherosclerosis

OBJECTIVE

vMIP-II (viral macrophage inflammatory protein 2)/vCCL2 (viral chemotactic cytokine ligand 2) binds to multiple chemokine receptors, and vMIP-II-based positron emission tomography tracer (64Cu-DOTA-vMIP-II: vMIP-II tracer) accumulates at atherosclerotic lesions in mice. Given that it would be expected to react with multiple chemokine receptors on monocytes and macrophages, we wondered if its accumulation in atherosclerosis lesion-bearing mice might correlate with overall macrophage burden or, alternatively, the pace of monocyte recruitment. Approach and Results: We employed a mouse model of atherosclerosis regression involving adenoassociated virus 8 vector encoding murine Apoe (AAV-mApoE) treatment of Apoe-/- mice where the pace of monocyte recruitment slows before macrophage burden subsequently declines. Accumulation of 64Cu-DOTA-vMIP-II at Apoe-/- plaque sites was strong but declined with AAV-mApoE-induced decline in monocyte recruitment, before macrophage burden reduced. Monocyte depletion indicated that monocytes and macrophages themselves were not the only target of the 64Cu-DOTA-vMIP-II tracer. Using fluorescence-tagged vMIP-II tracer, competitive receptor blocking with CXCR4 antagonists, endothelial-specific Cre-mediated deletion of CXCR4, CXCR4-specific tracer 64Cu-DOTA-FC131, and CXCR4 staining during disease progression and regression, we show endothelial cell expression of CXCR4 is a key target of 64Cu-DOTA-vMIP-II imaging. Expression of CXCR4 was low in nonplaque areas but strongly detected on endothelium of progressing plaques, especially on proliferating endothelium, where vascular permeability was increased and monocyte recruitment was the strongest.

CONCLUSIONS

Endothelial injury status of plaques is marked by CXCR4 expression and this injury correlates with the tendency of such plaques to recruit monocytes. Furthermore, our findings suggest positron emission tomography tracers that mark CXCR4 can be used translationally to monitor the state of plaque injury and monocyte recruitment.

Inhibition of the CCL2 receptor, CCR2, enhances tumor response to immune checkpoint therapy

Immunotherapies targeting the PD-1/PD-L1 axis are now a mainstay in the clinical management of multiple cancer types, however, many tumors still fail to respond. CCL2 is highly expressed in various cancer types and has been shown to be associated with poor prognosis. Inhibition or blockade of the CCL2/CCR2 signaling axis has thus been an area of interest for cancer therapy. Here we show across multiple murine tumor and metastasis models that CCR2 antagonism in combination with anti-PD-1 therapy leads to sensitization and enhanced tumor response over anti-PD-1 monotherapy. We show that enhanced treatment response correlates with enhanced CD8+ T cell recruitment and activation and a concomitant decrease in CD4+ regulatory T cell. These results provide strong preclinical rationale for further clinical exploration of combining CCR2 antagonism with PD-1/PD-L1-directed immunotherapies across multiple tumor types especially given the availability of small molecule CCR2 inhibitors and antibodies.

Targeted Molecular Iron Oxide Contrast Agents for Imaging Atherosclerotic Plaque

Overview: Cardiovascular disease remains a leading cause of death worldwide, with vulnerable plaque rupture the underlying cause of many heart attacks and strokes. Much research is focused on identifying an imaging biomarker to differentiate stable and vulnerable plaque. Magnetic Resonance Imaging (MRI) is a non-ionising and non-invasive imaging modality with excellent soft tissue contrast. However, MRI has relatively low sensitivity (micromolar) for contrast agent detection compared to nuclear imaging techniques. There is also an increasing emphasis on developing MRI probes that are not based on gadolinium chelates because of increasing concerns over associated systemic toxicity and deposits¹. To address the sensitivity and safety concerns of gadolinium this project focused on the development of a high relaxivity probe based on superparamagnetic iron oxide nanoparticles for the imaging of atherosclerotic plaque with MRI. With development, this may facilitate differentiating stable and vulnerable plaque in vivo.

Aim: To develop a range of MRI contrast agents based on superparamagnetic iron oxide nanoparticles (SPIONs), and test them in a murine model of advanced atherosclerosis.

Methods: Nanoparticles of four core sizes were synthesised by thermal decomposition and coated with poly(maleicanhydride-alt-1-octadecene) (PMAO), poly(ethyleneimine) (PEI) or alendronate, then characterised for core size, hydrodynamic size, surface potential and relaxivity. On the basis of these results, one candidate was selected for further studies. In vivo studies using 10 nm PMAO-coated SPIONs were performed in ApoE^-/- mice fed a western diet and instrumented with a perivascular cuff on the left carotid artery. Control ApoE^-/- mice were fed a normal chow diet and were not instrumented. Mice were scanned on a 3T MR scanner (Philips Achieva) with the novel SPION contrast agent, and an elastin-targeted gadolinium agent that was shown previously to enable visualisation of plaque burden. Histological analysis was undertaken to confirm imaging findings through staining for macrophages, CX3CL1, elastin, tropoelastin, and iron.

Results: The lead SPION agent consisted of a 10 nm iron oxide core with poly(maleicanhydride-alt-1-octadecene), (-36.21 mV, r² 18.806 mmol^-1/s^-1). The irregular faceting of the iron oxide core resulted in high relaxivity and the PMAO provided a foundation for further functionalisation on surface -COOH groups. The properties of the contrast agent, including the negative surface charge and hydrodynamic size, were designed to maximise circulation time and evade rapid clearance through the renal system or phagocytosis. In vitro testing showed that the SPION agent was non-toxic.

In vivo results show that the novel contrast agent accumulates in similar vascular regions to a gadolinium-based contrast agent (Gd-ESMA) targeted to elastin, which accumulates in plaque. There was a significant difference in SPION signal between the instrumented and the contralateral non-instrumented vessels in diseased mice (p = 0.0411, student's t-test), and between the instrumented diseased vessel and control vessels (p = 0.0043, 0.0022, student's t-test). There was no significant difference between the uptake of either contrast agent between stable and vulnerable plaques (p = 0.3225, student's t-test). Histological verification was used to identify plaques, and Berlin Blue staining confirmed the presence of nanoparticle deposits within vulnerable plaques and co-localisation with macrophages.

Conclusion: This work presents a new MRI contrast agent for atherosclerosis which uses an under-explored surface ligand, demonstrating promising properties for in vivo behaviour, is still in circulation 24 hours post-injection with limited liver uptake, and shows good accumulation in a murine plaque model.

High-fat diet-induced GAIT element-mediated translational silencing of mRNAs encoding inflammatory proteins in macrophage protects against atherosclerosis

Previously, we identified a mechanism of inflammation control directed by ribosomal protein L13a and "GAIT" (Gamma Activated Inhibitor of Translation) elements in target mRNAs and showed that its elimination in myeloid cell-specific L13a knockout mice (L13a KO) increased atherosclerosis susceptibility and severity. Here, we investigated the mechanistic basis of this endogenous defense against atherosclerosis. We compared molecular and cellular aspects of atherosclerosis in high-fat diet (HFD)-fed L13a KO and intact (control) mice. HFD treatment of control mice induced release of L13a from 60S ribosome, formation of RNA-binding complex, and subsequent GAIT element-mediated translational silencing. Atherosclerotic plaques from HFD-treated KO mice showed increased infiltration of M1 type inflammatory macrophages. Macrophages from KO mice showed increased phagocytic activity and elevated expression of LDL receptor and pro-inflammatory mediators. NanoString analysis of the plaques from KO mice showed upregulation of a number of mRNAs encoding inflammatory proteins. Bioinformatics analysis suggests the presence of the potential GAIT elements in the 3'UTRs of several of these mRNAs. Macrophage induces L13a/GAIT-dependent translational silencing of inflammatory genes in response to HFD as an endogenous defense against atherosclerosis in ApoE^-/- model.

Inflammatory Biomarkers for Cardiovascular Risk Stratification in Familial Hypercholesterolemia

Familial hypercholesterolemia (FH) is a frequent autosomal genetic disease characterized by elevated concentrations of low-density lipoprotein cholesterol (LDL) from birth with increased risk of premature atherosclerotic complications. Accumulating evidence has shown enhanced inflammation in patients with FH. In vessels, the deposition of modified cholesterol lipoproteins triggers local inflammation. Then, inflammation facilitates fatty streak formation by activating the endothelium to produce chemokines and adhesion molecules. This process eventually results in the uptake of vascular oxidized LDL (OxLDL) by scavenger receptors in monocyte-derived macrophages and formation of foam cells. Further leukocyte recruitment into the sub-endothelial space leads to plaque progression and activation of smooth muscle cells proliferation. Several inflammatory biomarkers have been reported in this setting which can be directly synthetized by activated inflammatory/vascular cells or can be indirectly produced by organs other than vessels, e.g., liver. Of note, inflammation is boosted in FH patients. Inflammatory biomarkers might improve the risk stratification for coronary heart disease and predict atherosclerotic events in FH patients. This review aims at summarizing the current knowledge about the role of inflammation in FH and the potential application of inflammatory biomarkers for cardiovascular risk estimation in these patients.

Modeling the Effects of Severe Metabolic Disease by Genome Editing of hPSC-Derived Endothelial Cells Reveals an Inflammatory Phenotype

The kinase AKT2 (PKB) is an important mediator of insulin signaling, for which loss-of-function knockout (KO) mutants lead to early onset diabetes mellitus, and dominant active mutations lead to early development of obesity and endothelial cell (EC) dysfunction. To model EC dysfunction, we used edited human pluripotent stem cells (hPSCs) that carried either a homozygous deletion of AKT2 (AKT2 KO) or a dominant active mutation (AKT2 E17K), which, along with the parental wild type (WT), were differentiated into ECs. Profiling of EC lines indicated an increase in proinflammatory and a reduction in anti-inflammatory fatty acids, an increase in inflammatory chemokines in cell supernatants, increased expression of proinflammatory genes, and increased binding to the EC monolayer in a functional leukocyte adhesion assay for both AKT2 KO and AKT2 E17K. Collectively, these findings suggest that vascular endothelial inflammation that results from dysregulated insulin signaling (homeostasis) may contribute to coronary artery disease, and that either downregulation or upregulation of the insulin pathway may lead to inflammation of endothelial cells. This suggests that the standard of care for patients must be expanded from control of metabolic parameters to include control of inflammation, such that endothelial dysfunction and cardiovascular disorders can ultimately be prevented.

Inhibitors of DAG metabolism suppress CCR2 signalling in human monocytes

BACKGROUND AND PURPOSE

CCL2 is an inflammatory chemokine that stimulates the recruitment of monocytes into tissue via activation of the GPCR CCR2.

EXPERIMENTAL APPROACH

Freshly isolated human monocytes and THP-1 cells were used. Fura-2 loaded cells were used to measure intracellular Ca²⁺ responses. Transwell migration to measure chemotaxis. siRNA-mediated gene knock-down was used to support pharmacological approaches.

KEY RESULTS

CCL2 evoked intracellular Ca²⁺ signals and stimulated migration in THP-1 monocytic cells and human CD14⁺ monocytes in a CCR2-dependent fashion. Attenuation of DAG catabolism in monocytes by inhibiting DAG kinase (R59949) or DAG lipase (RHC80267) activity suppressed CCL2-evoked Ca²⁺ signalling and transwell migration in monocytes. These effects were not due to a reduction in the number of cell surface CCR2. The effect of inhibiting DAG kinase or DAG lipase could be mimicked by addition of the DAG analogue 1-oleoyl-2-acetyl-sn-glycerol (OAG) but was not rescued by application of exogenous phosphatidylinositol 4,5-bisphosphate. Suppressive effects of R59949, RHC80267, and OAG were partially or fully reversed by Gö6983 (pan PKC isoenzyme inhibitor) but not by Gö6976 (PKCα and PKCβ inhibitor). RNAi-mediated knock-down of DAG kinase α isoenzyme modulated CCL2-evoked Ca²⁺ responses in THP-1 cells.

CONCLUSIONS AND IMPLICATIONS

Taken together, these data suggest that DAG production resulting from CCR2 activation is metabolised by both DAG kinase and DAG lipase pathways in monocytes and that pharmacological inhibition of DAG catabolism or application suppresses signalling on the CCL2-CCR2 axis via a mechanism dependent upon a PKC isoenzyme that is sensitive to Gö6983 but not Gö6976.

Serum Concentrations of Osteogenesis/Osteolysis-Related Factors and Micro-RNA Expression in ST-Elevation Myocardial Infarction

Background

Atherosclerosis and bone metabolism share similar molecular and cellular mechanisms. This study aims to evaluate (1) serum concentration of osteogenesis/osteolysis factors panel (Dickkopf-related protein 1 (DKK-1), TNF-α, N-terminal atrial natriuretic peptide (NT-proANP), thrombospondin-2 (TSP-2), osteoprotegerin (OPG), osteocalcin (OCN), osteopontin (OPN), fibroblast growth factor 23 (FGF-23), soluble receptor activator of nuclear factor-kappaB ligand (sRANKL), tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), proprotein convertase subtilisin/kexin type 9 (PCSK9)), (2) serum expression levels of micro-RNA- (miR-) 24-1 and miR-6802, and (3) assess their correlation with myocardial injury and LV remodeling and function in the acute phase of STEMI and after 3 months.

Methods

Study enrolled 25 STEMI patients (mean age 55.4 ± 8.96 years). Blood samples were collected 4 days and 3 months after myocardial infarction. Serum concentrations of osteogenesis/osteolysis factors were measured using the Luminex assay. Analysis of miR-24-1, and miR-6802 expression was performed with qPCR. LV function and remodeling were assessed by MRI during index hospitalization and 3 months later.

Results

There were no significant differences in serum levels of osteogenesis/osteolysis factors and expression of miR-24-1 and miR-6802 between the acute phase and 3-month follow-up. The levels were similar in patients with at least ≥5% improvement of LVEF (n = 10) and those without improvement. There was a negative correlation between the OPG serum level and LVEF during the acute phase of myocardial infarction.

Conclusions

In STEMI patients, serum concentrations of osteogenesis/osteolysis factors, as well as miR-24-1 and miR-6802 expression, do not change significantly within the 3-month follow-up and are not correlated with LV remodeling and function.

Protective Effects of Angong Niuhuang Pill on Early Atherosclerosis in ApoE-/- Mice by Reducing the Inflammatory Response

Atherosclerosis (AS) is the primary cause of cardiocerebrovascular disease, and inflammation is responsible for the initiation of its pathogenesis. Therefore, targeting inflammatory pathways to prevent AS progression is an ideal strategy. Angong Niuhuang pill (ANP) is a well-known traditional Chinese medicine and has been widely used for thousands of years to treat central nervous system and cardiovascular diseases. In this study, we investigated the role of ANP in reducing inflammation during early AS, using a high-fat diet-induced ApoE^−/− mouse model of AS. Compared to those with simvastatin, ANP had no significant effect on serum triglyceride, low-density lipoprotein, and high-density lipoprotein levels. However, it effectively inhibited splenic and vascular inflammation. This agent also reduced the Th17/CD4⁺T ratio and mRNA expression of IL-6 and increased the Treg/CD4⁺T ratio and mRNA expression of TGF-β1. Thus, ANP restored Th17/Treg homeostasis in the spleen. It also regulated pro- and anti-inflammatory cytokine expression in the aorta in a similar manner. Further, it downregulated the expression of chemokine receptors (CCR2, CXCR3), their ligands (MCP-1, MCP-2, and MCP-3), and cell adhesion molecules (VCAM-1, ICAM-1) in arterial vessels. These results indicate that ANP can ameliorate the development of early AS, mainly by reducing inflammation instead of acting as an antihyperlipidemic drug.

[68Ga]Pentixafor PET/MR imaging of chemokine receptor 4 expression in the human carotid artery

Purpose

Type 4 chemokine receptor (CXCR4) plays an important role in immune cell migration during the atherosclerosis progression. We aimed to evaluate [⁶⁸Ga]Pentixafor positron emission tomography (PET) in combination magnetic resonance imaging (MRI) for in vivo quantification of CXCR4 expression in carotid plaques.

Methods

Seventy-two patients with lymphoma were prospectively scheduled for whole body [⁶⁸Ga]Pentixafor PET/MRI with an additional T2-weighted carotid sequence. Volumes of interest (VOIs) were drawn along the carotid bifurcation regions, and the maximum tissue-to-blood ratios (TBR) of [⁶⁸Ga]Pentixafor uptake were calculated. Lesions were categorized into non-eccentric (n = 27), mild eccentric (n = 67), moderately (n = 41) and severely (n = 19) eccentric carotid atherosclerosis. A different cohort of symptomatic patients (n = 10) with carotid stenosis scheduled for thrombendarterectomy (TEA) was separately imaged with 3T MRI with dedicated plaque sequences (time of flight, T1-, and T2-weighted). MRI findings were correlated with histochemical assessment of intact carotid plaques.

Results

At hybrid PET/MRI, we observed significantly increased [⁶⁸Ga]Pentixafor uptake in mildly (mean TBR_max = 1.57 ± 0.27, mean SUV_max = 2.51 ± 0.39), moderately (mean TBR_max = 1.64 ± 0.37, mean SUV_max = 2.61 ± 0.55) and severely eccentric carotids (mean TBR_max = 1.55 ± 0.26, mean SUV_max = 2.40 ± 0.44) as compared to non-eccentric carotids (mean TBR_max = 1.29 ± 0.21, mean SUV_max = 1.77 ± 0.42) (p ≤ 0.05). Histological findings from TEA confirmed that prominent CXCR4 expression was localized within inflamed atheromas and preatheromas. Co-localization of cellular CXCR4 and CD68 expression in the plaque was observed by immunofluorescence staining.

Conclusions

In vivo evaluation of CXCR4 expression in carotid atherosclerotic lesions is feasible using [⁶⁸Ga]Pentixafor PET/MRI. In atherosclerotic plaque tissue, CXCR4 expression might be used as a surrogate marker for inflammatory atherosclerosis.

CircRNA‑0044073 is upregulated in atherosclerosis and increases the proliferation and invasion of cells by targeting miR‑107

Circular RNAs (circRNAs) are endogenous non‑coding RNAs implicated in atherosclerosis. The aim of the present study was to explore the function of circRNA‑0044073 in atherosclerosis. Reverse transcription quantitative polymerase chain reaction assays were used to measure the expression levels of circRNA‑0044073, microRNA (miRNA/miR)‑107, janus kinase 1 (JAK1), signal transducer and activator of transcription 3 (STAT3), B‑cell lymphoma 2 (Bcl‑2) and v‑myc avian myelocytomatosis viral oncogene homolog (c‑myc) in in blood cells from patients with atherosclerosis. RNA pull‑down and luciferase reporter assays were then used to determine the association between circRNA and miR expression, and miR and gene expression, respectively. Matrigel invasion assay and flow cytometry were used to analyze cell invasion and cell cycle. Western blot analysis and ELISA were used to evaluate the expression levels of proteins. It was identified that the expression of circRNA‑0044073 was upregulated and the expression of miR‑107 was downregulated in atherosclerotic blood cells. Overexpression of circRNA‑0044073 promoted the proliferation of human vascular smooth muscle cells (HUVSMCs) and human vascular endothelial cells (HUVECs), while overexpression of miR‑107 inhibited their proliferation. In addition, circRNA‑0044073 suppressed the levels of miR‑107 via a sponge mechanism. Lipopolysaccharide (LPS) affected the proliferation of HUVSMCs and HUVECs, and also resulted in changes in circRNA‑0044073 expression levels. CircRNA‑0044073 promoted the proliferation and invasion of HUVSMCs and HUVECs in spite of the opposite effect observed with LPS treatment. The JAK/STAT signaling pathway was activated in patients with atherosclerosis. CircRNA‑0044073 favored the activation of the JAK/STAT signaling pathway and inflammation in HUVSMCs and HUVECs. These data indicate that circRNA‑0044073 is upregulated in atherosclerosis and promotes the proliferation and invasion of cells by targeting miR‑107 and activating the JAK/STAT signaling pathway, potentially offering a target for novel treatment strategies against atherosclerosis.

Perivascular adipose tissue (PVAT) in atherosclerosis: a double-edged sword

Perivascular adipose tissue (PVAT), the adipose tissue that surrounds most of the vasculature, has emerged as an active component of the blood vessel wall regulating vascular homeostasis and affecting the pathogenesis of atherosclerosis. Although PVAT characteristics resemble both brown and white adipose tissues, recent evidence suggests that PVAT develops from its own distinct precursors implying a closer link between PVAT and vascular system. Under physiological conditions, PVAT has potent anti-atherogenic properties mediated by its ability to secrete various biologically active factors that induce non-shivering thermogenesis and metabolize fatty acids. In contrast, under pathological conditions (mainly obesity), PVAT becomes dysfunctional, loses its thermogenic capacity and secretes pro-inflammatory adipokines that induce endothelial dysfunction and infiltration of inflammatory cells, promoting atherosclerosis development. Since PVAT plays crucial roles in regulating key steps of atherosclerosis development, it may constitute a novel therapeutic target for the prevention and treatment of atherosclerosis. Here, we review the current literature regarding the roles of PVAT in the pathogenesis of atherosclerosis.

A severe atherosclerosis mouse model on the resistant NOD background

Atherosclerosis is a complex disease affecting arterial blood vessels and blood flow that could result in a variety of life-threatening consequences. Disease models with diverged genomes are necessary for understanding the genetic architecture of this complex disease. Non-obese diabetic (NOD) mice are highly polymorphic and widely used for studies of type 1 diabetes and autoimmunity. Understanding atherosclerosis development in the NOD strain is of particular interest as human atherosclerosis on the diabetic and autoimmune background has not been successfully modeled. In this study, we used CRISPR/Cas9 genome editing to genetically disrupt apolipoprotein E (ApoE) and low-density lipoprotein receptor (LDLR) expression on the pure NOD background, and compared phenotype between single-gene-deleted mice and double-knockout mutants with reference to ApoE-deficient C57BL/6 mice. We found that genetic ablation of Ldlr or Apoe in NOD mice was not sufficient to establish an atherosclerosis model, in contrast to ApoE-deficient C57BL/6 mice fed a high-fat diet (HFD) for over 12 weeks. We further obtained NOD mice deficient in both LDLR and ApoE, and assessed the severity of atherosclerosis and immune response to hyperlipidemia in comparison to ApoE-deficient C57BL/6 mice. Strikingly, the double-knockout NOD mice treated with a HFD developed severe atherosclerosis with aorta narrowed by over 60% by plaques, accompanied by destruction of pancreatic islets and an inflammatory response to hyperlipidemia. Therefore, we succeeded in obtaining a genetic model with severe atherosclerosis on the NOD background, which is highly resistant to the disease. This model is useful for the study of atherosclerosis in the setting of autoimmunity.

Nutritional Health Considerations for Persons with Spinal Cord Injury

Chronic spinal cord injury (SCI) often results in morbidity and mortality due to all-cause cardiovascular disease (CVD) and comorbid endocrine disorders. Several component risk factors for CVD, described as the cardiometabolic syndrome (CMS), are prevalent in SCI, with the individual risks of obesity and insulin resistance known to advance the disease prognosis to a greater extent than other established risks. Notably, adiposity and insulin resistance are attributed in large part to a commonly observed maladaptive dietary/nutritional profile. Although there are no evidence-based nutritional guidelines to address the CMS risk in SCI, contemporary treatment strategies advocate more comprehensive lifestyle management that includes sustained nutritional guidance as a necessary component for overall health management. This monograph describes factors in SCI that contribute to CMS risks, the current nutritional profile and its contribution to CMS risks, and effective treatment strategies including the adaptability of the Diabetes Prevention Program (DPP) to SCI. Establishing appropriate nutritional guidelines and recommendations will play an important role in addressing the CMS risks in SCI and preserving optimal long-term health.

Adverse effects on macrophage lipid transport and survival by high density lipoprotein from patients with coronary heart disease

High density lipoprotein (HDL)-macrophage interactions have the potential to modulate macrophage function in a beneficial way to prevent the development of lipid-loaded foam cell formation in atherosclerosis. Although HDL is atheroprotective, it can become dysfunctional in chronic inflammatory conditions and increase cardiovascular risk. Here, we examined the effect of dysfunctional-HDL from patients with coronary artery disease, on macrophage function in comparison to functional-HDL from controls. Exposure of macrophages to dysfunctional-HDL for 24 h resulted significant increase in cellular oxidative stress, cholesterol, and cytotoxicity. It also stimulated mitochondrial membrane depolarization, DNA damage, apoptosis, and cleavage of poly (ADP-ribose) polymerase, which are characteristics of proapoptotic pathways. In contrast, functional-HDL treatment maintained cholesterol homeostasis, essential membrane potential, DNA integrity, and cell survival. These results demonstrate that HDL from coronary artery disease (CAD) patient promotes proatherogenic effects that in turn trigger macrophage apoptosis, an important feature in atherogenesis and thereby providing new insight in our understanding of the atherogenic mechanisms.

Chemokine CC-motif ligand 2 participates in platelet function and arterial thrombosis by regulating PKCα-P38MAPK-HSP27 pathway

BACKGROUND

Studies indicate that chemokine CC-motif ligand 2 (CCL2) is involved in inflammation and atherosclerosis. However, the roles and mechanisms of CCL2 on platelet function and arterial thrombosis are unknown.

METHODS

The expressions of CCL2 or CCR2 in the plasma, platelets and coronary thrombus of ST-elevated myocardial infarction (STEMI) patients were examined by ELISA, Western blot, immunohistochemistry and immunofluorescence. The roles of CCL2 on platelet aggregation, activation and secretion were examined by light transmission aggregometry, flow cytometry and ELISA.

RESULTS

The expressions of CCL2 or CCR2 in the plasma or platelets of STEMI patients with platelet high response were higher than those with platelet normal response; In vitro, exogenous recombinant human CCL2 markedly increased platelet aggregation, activation and granule secretion, which were abolished by CCL2 neutralizing antibody or CCR2 inhibiter. CCL2 increased the phosphorylation levels of PKCα (Thr638), P38MAPK (Thr180/Tyr182) and HSP27 (S78/S82) in human platelets, which were abrogated by PKCα inhibitor (RO 318220) or P38MAPK inhibitor (SB 203580). RO 318220 or SB 203580 diminished CCL2-induced platelet function. In CCL2^-/- mice, platelet aggregation and secretion were attenuated; the phosphorylation of PKCα, P38MAPK and HSP27 were decreased. In a carotid arterial thrombus mouse model, CCL2^-/- mice displayed a significantly extended carotid artery occlusion time compared with wild type.

CONCLUSIONS

CCL2 played important roles in regulating platelet function and arterial thrombosis through the PKCα-P38MAPK-HSP27 pathway, which might provide theoretical basis for searching new antiplatelet drugs and the treatment for cardiovascular diseases.

Association of Sleep Quality With Cardiovascular Disease Risk and Mental Health in Law Enforcement Officers

OBJECTIVES

The aim of the study was to determine whether sleep quality is associated with an increased risk for cardiovascular disease (CVD) or worsened mental health.

METHODS

Self-reported sleep quality, 35 inflammatory factors, CVD risk factors, personal stress, police operational and organizational stress, social support, depressive symptoms, and health-related quality of life were compared among a cohort of officers.

RESULTS

Of 379 officers, 39% and 27% had poor and borderline sleep quality. Sleep quality was not associated with either an altered inflammatory profile or worsened CVD risk factors. Compared with good sleepers, borderline and poor sleepers reported increased personal stress, police organizational and operational stress, and depressive symptoms, but decreased health-related quality of life.

CONCLUSIONS

Poor sleep quality is prevalent in the law enforcement profession and is associated with worsened mental health but not with an increased risk for CVD.

Overexpression of complement component C5a accelerates the development of atherosclerosis in ApoE-knockout mice

BACKGROUND

In this study, we investigated the direct effect of C5a overexpression on atherosclerosis.

METHODS AND RESULTS

A recombinant adenovirus expressing mouse C5a (Ad-C5a) was constructed and injected intravenously into ApoE-/- mice. After 12 weeks of a high-fat diet, Ad-C5a injection produced more extensive lesions than control adenovirus, and its proathrosclerotic role was significantly blocked by C5a receptor antagonist. Immunohistochemical analysis showed enhanced macrophage infiltration in atherosclerotic regions with C5a overexpression. Trans-well assay revealed C5a receptor-dependent chemotaxis of C5a to macrophages. Furthermore, Ad-C5a overexpression promoted foam cell formation and lipid deposition but reduced collagen content. In addition, with Ad-C5a overexpression, the serum levels of interleukin 6 and tumor necrosis factor α were upregulated.

CONCLUSIONS

C5a overexpression could accelerate the development of atherosclerosis in ApoE-/- mice by promoting macrophage recruitment, foam cell formation and inflammatory activation. Furthermore, its proatherogetic role is mediated by the C5a receptor.

[68Ga]Pentixafor-PET/MRI for the detection of Chemokine receptor 4 expression in atherosclerotic plaques

PURPOSE

The expression of chemokine receptor type 4 (CXCR4) was found co-localized with macrophages on the atherosclerotic vessel wall and participated in the initial emigration of leukocytes. Gallium-68 [⁶⁸Ga]Pentixafor has recently been introduced for the imaging of atherosclerosis by targeting CXCR4. We sought to evaluate human atherosclerotic lesions using [⁶⁸Ga]Pentixafor PET/MRI.

METHODS

Thirty-eight oncology patients underwent [⁶⁸Ga]Pentixafor PET/MR imaging at baseline. Maximum standardized uptake values (SUV_max) were derived from hot lesions in seven arterial segments and target-to-blood ratios (TBR) were calculated. ANOVA post-hoc and paired t test were performed for statistical comparison, Spearman's correlation coefficient between uptake ratios and cardiovascular risk factors were assessed. The reproducibility of [⁶⁸Ga]Pentixafor PET/MRI was assessed in seven patients with a follow-up exanimation by Pearson's regression and Bland-Altman plots analysis.

RESULTS

Thirty-four of 38 patients showed 611 focal [⁶⁸Ga]Pentixafor uptake that followed the contours of the large arteries. Both prevalence and mean TBR_max were highest in the descending aorta. There were significantly higher TBR values found in men (1.9 ± 0.3) as compared to women (1.7 ± 0.2; p < 0.05). Patients with mean TBR_max > 1.7 showed a significantly higher incidence of diabetes, hypertension hypercholesterolemia and history of cardiovascular disease than patients with mean TBR_max ≤ 1.7. [⁶⁸Ga]Pentixafor uptake showed a good reproducibility (r = 0.6, p < 0.01), and there was no difference between the mean TBR_max values of plaque lesions (TBR_baseline1.8 ± 0.3 vs TBR_follow-up1.8 ± 0.3) (p = 0.9).

CONCLUSION

Patients with high arterial uptake showed increased incidence of cardiovascular risk factors, suggesting a potential role of [⁶⁸Ga]Pentixafor in characterization of atherosclerosis.

Radial artery intima-media thickness regresses after secondary prevention interventions in patients' post-acute coronary syndrome and is associated with cardiac and kidney biomarkers

BACKGROUND

Radial artery intima-media thickness (rIMT) measured by ultra-high-resolution ultrasound is associated with increased cardiovascular risk and predicts outcomes. We performed non-invasive high-resolution ultrasound of the radial artery to investigate vascular changes in subjects presenting with acute coronary syndrome (ACS) and who had undergone percutaneous coronary intervention (PCI).

PURPOSE

In the present work, we aimed to follow rIMT change over time post-acute coronary syndrome as a tool to monitor potential response to intensified medical therapy.

METHODS

We examined 256 subjects who underwent PCI due to ACS and healthy controls (n= 39) and we measured a number of biomarkers, which are known to be associated with cardiovascular disease. Images of radial artery were acquired bilaterally in the longitudinal view using a 50 MHz transducer (Vevo 2100 VisualSonics, Inc, Toronto, Ontario, Canada). Carotid IMT (cIMT) and rIMT were measured at <1 month after index PCI followed by a repeated measurement of rIMT at 4 months from the ACS in a sub-set (n=117).

RESULTS

rIMT measured within 1 month post ACS was significantly higher than rIMT after 4 months from ACS, (p < 0.0001), mean ± SD (rIMT right 0.35 ± 0.08; rIMT left 0.37 ± 0.08) vs. (rIMT right 0.29 ± 0.08; rIMT left 0.31 ± 0.09) respectively. There was no statistically significant change in cIMT. In healthy controls there were no changes in rIMT or cIMT overtime. High levels of CX3CL1 and myeloperoxidase measured within one month post ACS are associated with increase of rIMT, r=0.38 (p< 0.0001) and r=0.41 (p< 0.0001) respectively.

CONCLUSIONS

rIMT seem to decrease systemically after ACS and is accompanied with corresponding biomarker change. The cause and clinical implications of the observed decrement in rIMT after ACS need further studies.

Roles of Cells from the Arterial Vessel Wall in Atherosclerosis

Atherosclerosis has been identified as a chronic inflammatory disease of the arterial vessel wall. Accumulating evidence indicates that different cells from the tunica intima, media, adventitia, and perivascular adipose tissue not only comprise the intact and normal arterial vessel wall but also participate all in the inflammatory response of atherosclerosis via multiple intricate pathways. For instance, endothelial dysfunction has historically been considered to be the initiator of the development of atherosclerosis. The migration and proliferation of smooth muscle cells also play a pivotal role in the progression of atherosclerosis. Additionally, the fibroblasts from the adventitia and adipocytes from perivascular adipose tissue have received considerable attention given their special functions that contribute to atherosclerosis. In addition, numerous types of cytokines produced by different cells from the arterial vessel wall, including endothelium-derived relaxing factors, endothelium-derived contracting factors, tumor necrosis factors, interleukin, adhesion molecules, interferon, and adventitium-derived relaxing factors, have been implicated in atherosclerosis. Herein, we summarize the possible roles of different cells from the entire arterial vessel wall in the pathogenesis of atherosclerosis.

Association between chemokine CXC ligand 12 gene polymorphism (rs1746048) and coronary heart disease: A MOOSE-compliant meta-analysis

Recently a large number of investigations have implicated the association between the chemokine CXC ligand 12 gene polymorphism (rs1746048) and risk of coronary heart disease (CHD), but the results remain debatable. The aim of our study was to provide more compelling evidence for the relationship between rs1746048 and CHD risk. Studies eligible for this meta-analysis were identified through electronic search of PubMed, EMBASE, and CNKI. Two authors performed independent literature review and study quality assessment by using the Newcastle-Ottawa Scale checklist. The odds ratios (ORs) with 95% confidence intervals (CIs) were pooled in a specific genetic model to assess the association. The meta-analysis of 48,852 patients and 64,386 controls from 12 studies showed that patients with rs1746048 had 1.11 times of high risk in developing CHD (OR = 1.11; 95% CI = 1.09-1.14; P < .005; I = 35.8%). The increased risk of CHD was also found in both Asian (OR = 1.07; 95%CI = 1.02-1.12; P < .005; I = 40.6%) and Caucasian populations (OR = 1.14; 95% CI = 1.10-1.18; P < .005; I = 22.2%). The results of our meta-analysis suggested that chemokine CXC ligand 12 gene polymorphism (rs1746048) may be linked with susceptibility to CHD.

Sinigrin attenuates the progression of atherosclerosis in ApoE-/- mice fed a high-cholesterol diet potentially by inhibiting VCAM-1 expression

Atherosclerosis is a complex inflammatory disease associated with elevated levels of atherogenic molecules for leukocyte recruitment. Sinigrin (2-propenylglucosinolate) is found mainly in broccoli, brussels sprouts, and black mustard seeds. Recently, sinigrin has received attention for its role in disease prevention and health promotion. In this study, we examined the effect of sinigrin on development of atherosclerosis in ApoE^-/- mice and the expression of adhesion molecules in vascular smooth muscle cells (VSMCs). The serum concentrations of lactate dehydrogenase (LDH), triglyceride (TG), total cholesterol (TC), low density lipoprotein (LDL), calcium (Ca²⁺), and pro-inflammatory cytokines were reduced by sinigrin treatment in ApoE^-/- mice. In addition, oral administration of sinigrin attenuated the mRNA expression of vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), C-C motif chemokine ligand 2 (CCL2), and CCL5 on aorta tissues and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR), liver X receptor (LXR), sterol regulatory element-binding protein-2 (SREBP-2), and low density lipoprotein receptor (LDLR) on liver tissues in ApoE^-/- mice. To provide a potential mechanism underlying the action of sinigrin, we evaluated the in vitro effect of sinigrin on the expression of the VCAM-1 in TNF-α-induced VSMCs. The increased expression of VCAM-1 by TNF-α stimulation was significantly suppressed by the treatment of sinigrin (1-100 μg/ml) and sinigrin inhibited the nuclear translocation of NF-κB and the phosphorylation of p38 MAPK and JNK pathways, suggesting that sinigrin decreases the TNF-α-stimulated VCAM-1 expression through the suppression of NF-κB and MAP kinases signaling pathways. Overall, sinigrin has the potential to be used in reducing the risks of atherosclerosis.

Protein kinase A regulates the Ras, Rap1 and TORC2 pathways in response to the chemoattractant cAMP in Dictyostelium

Efficient directed migration requires tight regulation of chemoattractant signal transduction pathways in both space and time, but the mechanisms involved in such regulation are not well understood. Here, we investigated the role of protein kinase A (PKA) in controlling signaling of the chemoattractant cAMP in Dictyostelium discoideum We found that cells lacking PKA display severe chemotaxis defects, including impaired directional sensing. Although PKA is an important regulator of developmental gene expression, including the cAMP receptor cAR1, our studies using exogenously expressed cAR1 in cells lacking PKA, cells lacking adenylyl cyclase A (ACA) and cells treated with the PKA-selective pharmacological inhibitor H89, suggest that PKA controls chemoattractant signal transduction, in part, through the regulation of RasG, Rap1 and TORC2. As these pathways control the ACA-mediated production of intracellular cAMP, they lie upstream of PKA in this chemoattractant signaling network. Consequently, we propose that the PKA-mediated regulation of the upstream RasG, Rap1 and TORC2 signaling pathways is part of a negative feedback mechanism controlling chemoattractant signal transduction during Dictyostelium chemotaxis.

Unliganded estrogen receptor alpha regulates vascular cell function and gene expression

The unliganded form of the estrogen receptor is generally thought to be inactive. Our prior studies, however, suggested that unliganded estrogen receptor alpha (ERα) exacerbates adverse vascular injury responses in mice. Here, we show that the presence of unliganded ERα decreases vascular endothelial cell (EC) migration and proliferation, increases smooth muscle cell (SMC) proliferation, and increases inflammatory responses in cultured ECs and SMCs. Unliganded ERα also regulates many genes in vascular ECs and mouse aorta. Activation of ERα by E2 reverses the cell physiological effects of unliganded ERα, and promotes gene regulatory effects that are predicted to counter the effects of unliganded ERα. These results reveal that the unliganded form of ERα is not inert, but significantly impacts gene expression and physiology of vascular cells. Furthermore, they indicate that the cardiovascular protective effects of estrogen may be connected to its ability to counteract these effects of unliganded ERα.

Susceptibility to chronic social stress increases plaque progression, vulnerability and platelet activation

Supplementary Material to this article is available online at www.thrombosis-online.com.

High-density lipoprotein from subjects with coronary artery disease promotes macrophage foam cell formation: role of scavenger receptor CD36 and ERK/MAPK signaling

Although high-density lipoprotein is atheroprotective, it can become dysfunctional in chronic inflammatory conditions and increase cardiovascular risk. We previously demonstrated that HDL from subjects with documented coronary artery disease is dysfunctional and is pro-oxidant/proinflammatory in macrophages. Here we examined the influence of dysfunctional/proinflammatory HDL (piHDL) on lipid accumulation in human macrophages, in comparison to functional HDL (nHDL). Exposure of macrophages to piHDL, in contrast to nHDL, resulted in oxidative stress and marked uptake of lipids from piHDL, leading to the formation of foam cell phenotype as noted by oil red O staining with concomitant increase in total cellular cholesterol content. Using western blotting, we identified that piHDL profoundly upregulated the expression of scavenger receptor CD36 and suppressed the expression of ABCG1 and SRB1 in macrophages, thereby facilitating cholesterol influx capacity of macrophages. We then identified that CD36 did not act alone, indeed it was activated in macrophages along with ERK/MAPK, in response to piHDL, which in turn led to lipid accumulation as well as proinflammatory response via activation of NFkB and subsequent release of proinflammatory markers-TNF-ά and MMP-9. These effects were confirmed using pharmacological inhibitors for either CD36 or ERK/MAPK. Furthermore, piHDL treatment moderately activated PPAR-γ and Nrf2, the known regulators of CD36 in macrophages, suggesting that the two forms of HDL differentially regulate CD36 expression. Taken together, the results demonstrate that a novel CD36-ERK/MAPK-dependent mechanism is involved in macrophage lipid accumulation by piHDL, there by revealing the importance of functional deficiency in HDL and its potential link to atherogenesis.