Plaque regression and plaque stabilisation in cardiovascular diseases

Statin therapy and cardiovascular protection in type 2 diabetes: The role of baseline LDL-Cholesterol levels. A systematic review and meta-analysis of observational studies

AIM

The guidelines recommend statins to prevent cardiovascular events in patients with type 2 diabetes (T2D) however, the importance of baseline LDL-Cholesterol (LDL-C) levels remains controversial. This study aimed to determine the association of statin use in T2D patients with major adverse cardiovascular events (MACE) and all-cause mortality and whether this association differs by baseline LDL-C levels.

DATA SYNTHESIS

Medline, Embase, and Web of Science were systematically searched from inception until January 2022. Observational studies in patients with T2D comparing statin users vs non-users, with reports of the baseline LDL-C levels, were included. Random-effects meta-analysis and meta-regression were performed to estimate the overall effect on the risk of all-cause mortality and MACE (a composite of myocardial infarction, heart failure, stroke, and revascularization events) and the modification in the association by baseline LDL-C levels. We categorized studies according to their baseline LDL-C levels into 1) <100 mg/dl (2.59 mmol/l), 2) 100-130 mg/dl (2.59-3.37 mmol/l) and 3) >130 mg/dl (3.37 mmol/l) categories. A total of 9 cohort studies (n = 403,411 individuals) fulfilled our criteria. The follow-up duration ranged from 1.7 to 8 years. The overall combined estimate showed that statin therapy was associated with a significantly lower risk of MACE (Hazard Ratio (HR): 0.70 [95% CI 0.59 to 0.83], Absolute risk reduction percentage (ARR%): 3.19% [95%CI 0.88 to 5.50%) and all-cause mortality (HR: 0.60 [95% CI 0.46 to 0.79], ARR%: 5.23% [95% CI 2.18 to 8.28%), but varied, albeit not statistically significant, by baseline LDL-C levels. Studies with baseline LDL-C levels higher than 130 mg/dl had the greatest reduction of MACE (HR: 0.58 [95% CI 0.37 to 0.90]) and all-cause mortality risk (HR: 0.51 [95% CI [ 0.29 to 0.90]). The HRs of MACE in studies with LDL-C levels of 100-130 mg/dl and <100 mg/dl categories were respectively (0.70 [95% CI 0.59 to 0.83]) and (0.83 [95% CI [0.68 to 1.00]); and that of all-cause mortality were respectively (0.62 [95% CI 0.38 to 1.01]) and (0.67 [95% CI [0.44 to 1.02]). Statin use changes the HRs of MACE (0.99 [95%CI, 0.98 to 0.99]; P = 0.04) and all-cause mortality (0.99 [95% CI 0.98 to 1.01]; P = 0.8) per each mg/dl increase in baseline LDL-C level in meta-regression analyses.

CONCLUSION

Statin therapy in patients with T2D was associated with reduced risk of MACE and all-cause mortality. Significant differences across studies with different baseline LDL-C levels were not observed.

Update on cardiac imaging: A critical analysis

Imaging is instrumental in diagnosing and directing the management of atherosclerosis. In 1958 the first diagnostic coronary angiography (CA) was performed, and since then further development has led to new methods such as coronary CT angiography (CTA), optical coherence tomography (OCT), positron tomography (PET), and intravascular ultrasound (IVUS). Currently, CA remains powerful for visualizing coronary arteries; however, recent studies show the benefits of using other non-invasive techniques. This review identifies optimum imaging techniques for diagnosing and monitoring plaque stability. This becomes even direr now, given the rapidly rising incidence of atherosclerosis in society today. Many acute coronary events, including acute myocardial infarctions and sudden deaths, are attributable to plaque rupture. Although fatal, these events can be preventable. We discuss the factors affecting plaque integrity, such as increased inflammation, medications like statins, and increased lipid content. Some of these precipitating factors are identifiable through imaging. However, we also highlight significant complications arising in some modalities; in CA this can include ventricular arrhythmia and even death. Extending this, we elucidated from the literature that risk can also vary based on the location of arteries and their plaques. Promisingly, there are less invasive methods being trialled for assessing plaque stability, such as Cardiac Magnetic Resonance Imaging (CMR), which is already in use for other cardiac diseases like cardiomyopathies. Therefore, future research focusing on using imaging modalities in conjunction may be sensible, to bridge between the effectiveness of modalities, at the expense of increased complications, and vice versa.

Secreted protein profiling of human aortic smooth muscle cells identifies vascular disease associations

Background

Smooth muscle cells (SMCs), which make up the medial layer of arteries, are key cell types involved in cardiovascular diseases (CVD), the leading cause of mortality and morbidity worldwide. In response to microenvironment alterations, SMCs dedifferentiate from a "contractile" to a "synthetic" phenotype characterized by an increased proliferation, migration, production of extracellular matrix (ECM) components, and decreased expression of SMC-specific contractile markers. These phenotypic changes result in vascular remodeling and contribute to the pathogenesis of CVD, including coronary artery disease (CAD), stroke, hypertension, and aortic aneurysms. Here, we aim to identify the genetic variants that regulate ECM secretion in SMCs and predict the causal proteins associated with vascular disease-related loci identified in genome-wide association studies (GWAS).

Methods

Using human aortic SMCs from 123 multi-ancestry healthy heart transplant donors, we collected the serum-free media in which the cells were cultured for 24 hours and conducted Liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based proteomic analysis of the conditioned media.

Results

We measured the abundance of 270 ECM and related proteins. Next, we performed protein quantitative trait locus mapping (pQTL) and identified 20 loci associated with secreted protein abundance in SMCs. We functionally annotated these loci using a colocalization approach. This approach prioritized the genetic variant rs6739323-A at the 2p22.3 locus, which is associated with lower expression of LTBP1 in SMCs and atherosclerosis-prone areas of the aorta, and increased risk for SMC calcification. We found that LTBP1 expression is abundant in SMCs, and its expression at mRNA and protein levels was reduced in unstable and advanced atherosclerotic plaque lesions.

Conclusions

Our results unravel the SMC proteome signature associated with vascular disorders, which may help identify potential therapeutic targets to accelerate the pathway to translation.

Gas station in blood vessels: An endothelium mimicking, self-sustainable nitric oxide fueling stent coating for prevention of thrombosis and restenosis

Stenting is the primary treatment for vascular obstruction-related cardiovascular diseases, but it inevitably causes endothelial injury which may lead to severe thrombosis and restenosis. Maintaining nitric oxide (NO, a vasoactive mediator) production and grafting endothelial glycocalyx such as heparin (Hep) onto the surface of cardiovascular stents could effectively reconstruct the damaged endothelium. However, insufficient endogenous NO donors may impede NO catalytic generation and fail to sustain cardiovascular homeostasis. Here, a dopamine-copper (DA-Cu) network-based coating armed with NO precursor L-arginine (Arg) and Hep (DA-Cu-Arg-Hep) is prepared using an organic solvent-free dipping technique to form a nanometer-thin coating onto the cardiovascular stents. The DA-Cu network adheres tightly to the surface of stents and confers excellent NO catalytic activity in the presence of endogenous NO donors. The immobilized Arg functions as a NO fuel to generate NO via endothelial nitric oxide synthase (eNOS), while Hep works as eNOS booster to increase the level of eNOS to decompose Arg into NO, ensuring a sufficient supply of NO even when endogenous donors are insufficient. The synergistic interaction between Cu and Arg is analogous to a gas station to fuel NO production to compensate for the insufficient endogenous NO donor in vivo. Consequently, it promotes the reconstruction of natural endothelium, inhibits smooth muscle cell (SMC) migration, and suppresses cascading platelet adhesion, preventing stent thrombosis and restenosis. We anticipate that our DA-Cu-Arg-Hep coating will improve the quality of life of cardiovascular patients through improved surgical follow-up, increased safety, and decreased medication, as well as revitalize the stenting industry through durable designs.

Inhibition of Atherosclerosis and Liver Steatosis by Agmatine in Western Diet-Fed apoE-Knockout Mice Is Associated with Decrease in Hepatic De Novo Lipogenesis and Reduction in Plasma Triglyceride/High-Density Lipoprotein Cholesterol Ratio

Atherosclerosis and NAFLD are the leading causes of death worldwide. The hallmark of NAFLD is triglyceride accumulation caused by an imbalance between lipogenesis de novo and fatty acid oxidation. Agmatine, an endogenous metabolite of arginine, exerts a protective effect on mitochondria and can modulate fatty acid metabolism. In the present study, we investigate the influence of agmatine on the progression of atherosclerotic lesions and the development of hepatic steatosis in apoE^−/− mice fed with a Western high-fat diet, with a particular focus on its effects on the DNL pathway in the liver. We have proved that treatment of agmatine inhibits the progression of atherosclerosis and attenuates hepatic steatosis in apoE^−/− mice on a Western diet. Such effects are associated with decreased total macrophage content in atherosclerotic plaque as well as a decrease in the TG levels and the TG/HDL ratio in plasma. Agmatine also reduced TG accumulation in the liver and decreased the expression of hepatic genes and proteins involved in lipogenesis de novo such as SREBP-1c, FASN and SCD1. In conclusion, agmatine may present therapeutic potential for the treatment of atherosclerosis and fatty liver disease. However, an exact understanding of the mechanisms of the advantageous actions of agmatine requires further study.

Role of vitamin D in the pathogenesis of atheromatosis

BACKGROUND AND AIMS

Cardiovascular disease is the main cause of death worldwide, but the collective efforts to prevent this pathological condition are directed exclusively to individuals at higher risk due to hypercholesterolemia, hypertension, obesity, diabetes. Recently, vitamin D deficiency was identified as a risk factor for cardiovascular disease in healthy people, as it predisposes to different vascular dysfunctions that can result in plaque development and fragility. In this scenario, the fundamental aim of the study was to reproduce a disease model inducing vitamin D deficiency and atheromatosis in ApoE-/- mice and then to evaluate the impact of this vitamin D status on the onset/progression of atheromatosis, focusing on plaque formation and instability.

METHODS AND RESULTS

In our murine disease model, vitamin D deficiency was achieved by 3 weeks of vitamin D deficient diet along with intraperitoneal paricalcitol injections, while atheromatosis by western-type diet administration. Under these experimental conditions, vitamin D deficient mice developed more unstable atheromatous plaques with reduced or absent fibrotic cap. Since calcium and phosphorus metabolism and also cholesterol and triglycerides systemic concentration were not affected by vitamin D level, our results highlighted the role of vitamin D deficiency in the formation/instability of atheromatous plaque and, although further studies are needed, suggested a possible intervention with vitamin D to prevent or delay the atheromatous disease.

CONCLUSIONS

The data obtained open the question about the potential role of the vitamins in the pharmacological treatments of cardiovascular disorders as coadjutant of the primary drugs used for these pathologies.

Endothelial progenitor cell-derived exosomes ameliorate endothelial dysfunction in a mouse model of diabetes

Atherosclerosis is a serious cardiovascular complication of diabetes characterized by inflammation and endothelial damage. Indeed, dysfunction of the endothelium is considered an early marker of atherosclerosis. Endothelial progenitor cells (EPCs) are prerequisites for blood vessels lined with endothelial cells (ECs), which produce many factors to regulate blood vessel function. Importantly, EPCs also repair some dysfunctions in ECs. Exosomes have been associated with the occurrence and development of disease. Here, we analyzed the microRNAs (miRNAs) contained in exosomes derived from EPCs by using next-generation sequencing. We found that most of the top 10 highest expressed miRNAs in these exosomes were related to atherosclerosis. In a mouse model of atherosclerotic diabetes, treatment with EPC-derived exosomes significantly reduced the production of diabetic atherosclerotic plaques and inflammatory factors. In an in vitro assay examining the contractility of the thoracic aorta from these mice, the addition of EPC-derived exosomes significantly ameliorated the observed endothelium-dependent contractile dysfunction. Taken together, these results indicated that EPC-derived exosomes ameliorated atherosclerotic endothelial dysfunction in a mouse model of atherosclerotic diabetes. Thus, the present study provides a potential therapeutic application of EPC-derived exosomes in cardiovascular disease.

Atherosclerotic Plaque Regression: Cause of Bypass Graft Oclussion

We present a case of a patient who had coronary artery bypass grafting during surgery for severe aortic stenosis. Seven months after surgery the arterial graft was occluded following native coronary artery disease regression. The heart team must consider this possibility when assessing the requirement for bypass grafts in a borderline lesion.

Safety and Efficacy of Extremely Low LDL-Cholesterol Levels and Its Prospects in Hyperlipidemia Management

The risk of cardiovascular disease has been reported to have a linear relationship with LDL levels. Additionally, the currently recommended LDL target goal of 70 mg/dl does not diminish the CV risk entirely leaving behind some residual risk. Previous attempts to maximally lower the LDL levels with statin monotherapy have met dejection due to the increased side effects associated with the treatment. Nevertheless, with the new advancements in clinical medicine, it has now become possible to bring down the LDL levels to as low as 15 mg/dl using PCSK9 monoclonal antibodies alone or in combination with statins. The development of inclisiran, siRNA silencer targeting PCSK9 gene, is a one step forward in these endeavors. Moreover, various studies aiming to lower the CV risk and mortality by lowering LDL levels have demonstrated encouraging results. The current challenge is to explore this arena to redefine the target LDL levels, if required, to avoid any suboptimal treatment. After thorough literature search in the PubMed, Embase, Scopus, and Google Scholar, we present this article to provide a brief overview of the safety and efficacy of lowering LDL below the current goal.

Standardized fraction of Xylocarpus moluccensis fruits improve vascular relaxation and plaque stability in dyslipidemic models of atherosclerosis

ETHNOPHARMACOLOGICAL RELEVANCE

Xylocarpus moluccensis (Lamk.) M. Roem of family Meliaceae has triterpenoids rich fruits. Triterpenoids have been known to possess cardioprotection and anti-atherosclerotic activities (Han and Bakovic, 2015; Wu et al., 2009). Standardized fraction of these fruits exhibited anti-dyslipidemic (Srivastava et al., 2015), anti-inflammatory (Ravangpai et al., 2011) and CNS depressant activity (Sarker et al., 2007). However, there is no report in the literature on its cardiovascular effects.

AIM OF THE STUDY

The present study was undertaken to assess vasoprotective, anti-atherosclerotic and further examine the anti-dyslipidemic effect of the standardized fraction of Xylocarpus moluccensis (F018) fruits in the mechanical injury and high fat diet (HFD) induced dyslipidemic/ atherosclerosis models.

MATERIALS AND METHODS

Guinea pigs were fed 0.08% cholesterol + 15% fat diet for 3 weeks, while ApoE KO mice were fed high fat diet for 18 weeks to induce dyslipidemia and atherosclerosis. A combination of balloon injury and high fat diet (1% cholesterol, 6% peanut oil) for 5 weeks was used to accelerate atherosclerosis in NZW rabbits. F018 was administered once daily by oral route in guinea pigs (10, 25 or 50mg/kg/day for 3 weeks), ApoE KO mice (50mg/kg/day for 6 weeks) and in NZW rabbit (25mg/kg/day for 5 weeks) to monitor its effect on dyslipidemia, vasoreactivity and plaque composition by using standard methodologies.

RESULTS

F018 treatment in guinea pigs (25 and 50mg/kg/day), ApoE mice (50mg/kg/day) and rabbits (25mg/kg/day) significantly reduced plasma lipids and improved ACh induced vasorelaxation. Anti-dyslipidemic effect of F018 seems to be due to the modulation of enterohepatic genes involved in the cholesterol absorption and excretion. Moreover, significant improvement in the acetylcholine (ACh) induced vasorelaxation was accompanied with reduced inflammatory burden and enhanced activation of eNOS in ApoE mice aortic tissue. Similarly inflammatory cytokines, immunolabeling of macrophage marker (CD68) and MMP-9 were reduced along with augmentation in vascular smooth muscle cells and collagen type I and III in the mechanically injured iliac artery segment in the rabbits.

CONCLUSIONS

Altogether, F018 preserved vasoreactivity, reduced atherosclerotic plaque progression and enhanced plaque stability by reducing lipids, inflammatory cytokines, improving endothelial function and collagen content.

Inhibiting Integrin α5 Cytoplasmic Domain Signaling Reduces Atherosclerosis and Promotes Arteriogenesis

Background

Fibronectin in endothelial basement membranes promotes endothelial inflammatory activation and atherosclerosis but also promotes plaque stability and vascular remodeling. The fibronectin receptor α5 subunit is proinflammatory through binding to and activating phosphodiesterase 4D5, which inhibits anti‐inflammatory cyclic adenosine monophosphate and protein kinase A. Replacing the α5 cytoplasmic domain with that of α2 resulted in smaller atherosclerotic plaques. Here, we further assessed plaque phenotype and compensatory vascular remodeling in this model.

Methods and Results

α5/2 mice in the hyperlipidemic apolipoprotein E null background had smaller plaques in the aortic root, with reduced endothelial NF‐κB activation and inflammatory gene expression, reduced leukocyte content, and much lower metalloproteinase expression. However, smooth muscle cell content, fibrous cap thickness, and fibrillar collagen were unchanged, indicating no shift toward vulnerability. In vivo knockdown of phosphodiesterase 4D5 also decreased endothelial inflammatory activation and atherosclerotic plaque size. α5/2 mice showed improved recovery from hindlimb ischemia after femoral artery ligation.

Conclusions

Blocking the fibronectin‐Integrin α5 pathway reduces atherosclerotic plaque size, maintains plaque stability, and improves compensatory remodeling. This pathway is therefore a potential therapeutic target for treatment of atherosclerosis.

Differential expression of T cell-related genes in AMI and SA stages of coronary artery disease

OBJECTIVE

To identify differentially expressed T cells-related genes in peripheral blood mononuclear cells and compare their differences in T cell activation and subset functions in different stages of coronary atherosclerosis disease (CAD).

METHODS

20 patients with acute myocardial infarction patients (AMI), 20 patients with stable angina pectoris (SA) and 20 healthy volunteers were recruited into the study. Whole human genome microarray analysis was used to detect the expression of T cell related genes among three groups.

RESULTS

mRNA expression of 68 genes involved in T cell was detected. 1) Antigen recognition: in the AMI patients 12 genes were down-regulated and 9 were significantly down-regulated among all 13 genes, compared with those of the SA and the control group, respectively. 2) Co-stimulators and regulators of T cell activation: among 16 genes in the AMI patients, 15 genes were lower and 8 were significantly lower than the other two groups. 3) T cell subsets, CTL: all 11 genes in the AMI patients were down-regulated, particularly GZMM and CASP8 were significantly down-regulated compared with the SA patients and controls. Th1/Th2: in the AMI patients, gene expressions including IL1 and IL18 were significantly higher, whereas GATA3 mRNA was significantly lower than those in other two groups. Th17/Treg: in the AMI group, RORC and CCR6 mRNAs were significantly down-regulated compared with the control group, while CD25 and CD127 expressions were significantly lower than SA group. There was no difference in T cell related genes between the SA patients and the controls.

CONCLUSIONS

In the AMI patients, the mRNA expression of T cell antigen recognition, activation and subset functions was imbalanced or decreased, indicating the dysfunction of cellular immunity in patients with AMI. Then improving T cell mediated cellular immunity may be considered as a potential target for medical interventions in the patients with AMI.

CCR5 facilitates endothelial progenitor cell recruitment and promotes the stabilization of atherosclerotic plaques in ApoE-/- mice

Introduction

Unstable atherosclerotic plaques are prone to rupture, which leads to atherothrombosis. Endothelial progenitor cells (EPCs) are bone marrow-derived precursor cells that may repair vascular injury in atherosclerosis. Chemokine (C-C motif) receptor 5 (CCR5) promotes mobilization of EPCs. In this study, we investigated the therapeutic potential of CCR5-overexpressing EPCs on plaque stabilization in an apolipoprotein E (ApoE)^−/− mouse model.

Methods

The expression of CCR5 and its cognate ligand chemokine (C-C motif) ligand 5 (CCL5) was examined in atherosclerotic aortas of humans and mice by immunohistochemistry. Splenectomized ApoE^−/− C57BL/6 J mice fed a high-fat diet for 24 weeks were intravenously injected with EPCs transfected with CCR5 overexpression lentivirus. The recruitment of EPCs over the atherosclerotic plaques was evaluated by immunofluorescence. The content of lipid, smooth muscle cells, monocytes/macrophages, and endothelial cells in atherosclerotic plaques was assayed by specific immunostaining. The serum levels of atherosclerosis-related inflammatory factors in ApoE^−/− mice were measured by mouse atherosclerosis antibody array I.

Results

CCR5 and CCL5 are highly expressed in atherosclerotic plaques in both humans and mice. The ApoE^−/− mice with CCR5-overexpressing EPC treatment demonstrated a more stable plaque formation with enhanced recruitment of EPC, reduced lipid, and macrophage content in the atherosclerotic plaques. CCR5-overexpressing EPC treatment also increased the content of endothelial cells and nitric oxide production in the plaques. In addition, the serum levels of interleukin-3 (IL-3), IL-5, IL-6, IL-13, CD40, and tumor necrosis factor-alpha and the plaque contents of IL-6 and matrix metalloproteinase-9 were reduced in mice with CCR5-overexpressing EPC treatment.

Conclusions

These findings suggest that CCR5 is a novel therapeutic target in EPC treatment for stabilization of atherosclerotic plaques.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0026-0) contains supplementary material, which is available to authorized users.