Apoptotic cell death in atherosclerosis

Iron, lipid peroxidation, and ferroptosis play pathogenic roles in atherosclerosis

Oxidation of lipids, excessive cell death, and iron deposition are prominent features of human atherosclerotic plaques. While extensive research has established the detrimental roles of lipid oxidation and apoptosis in atherosclerosis development, the involvement of iron in atherogenesis is not yet fully understood. With the emergence of an iron-dependent form of cell death termed ferroptosis, new attention has been brought to the complex inter-play among iron, ferroptosis, and atherosclerosis. Mechanistically, ferroptosis is caused by the lethal accumulation of iron-mediated lipid peroxides. Emerging studies have underscored ferroptosis as a contributor to worsened atherosclerosis. Herein, we review the evidence that oxidative damage and iron overload in the context of atherosclerosis may promote ferroptosis within plaques. Furthermore, we summarize recent findings of lipid peroxidation, thereby potentially ferroptosis, in various plaque cell types-such as endothelial cells, macrophages, dendritic cells, T cells, and vascular smooth muscle cells-across different stages of atherosclerosis. Understanding how these processes influence atherosclerotic plaque progression may permit targeting stage-dependent ferroptosis in each cell population and could provide a rationale for developing cell type-specific intervention strategies to mitigate atherogenic ferroptosis effectively.

Atherosclerosis: A Comprehensive Review of Molecular Factors and Mechanisms

Atherosclerosis, a condition characterized by the accumulation of lipids and a culprit behind cardiovascular events, has long been studied. However, in recent years, there has been an increase in interest in its initiation, with researchers shifting focus from traditional pathways involving the vascular infiltration of oxidized lipids and towards the novel presence of chronic inflammatory pathways. The accumulation of pro-inflammatory cytokines, in combination with the activation of transcription factors, creates a positive feedback loop that drives the creation and progression of atherosclerosis. From the upregulation of the nod-like receptor protein 3 (NLRP3) inflammasome and the Notch and Wnt pathways to the increased expression of VEGF-A and the downregulation of connexins Cx32, Cx37, and Cx40, these processes contribute further to endothelial dysfunction and plaque formation. Herein, we aim to provide insight into the molecular pathways and mechanisms implicated in the initiation and progression of atherosclerotic plaques, and to review the risk factors associated with their development.

N6-methyladenosine (m6A) modification in inflammation: a bibliometric analysis and literature review

N6-methyladenosine (m6A) is the most abundant internal messenger RNA modification in eukaryotes, influencing various physiological and pathological processes by regulating RNA metabolism. Numerous studies have investigated the role of m6A in inflammatory responses and inflammatory diseases. In this study, VOSviewer and Citespace were used to perform bibliometric analysis to systematically evaluating the current landscape of research on the association between m6A and inflammation. The literature was sourced from the Web of Science Core Collection, with characteristics including year, country/region, institution, author, journal, citation, and keywords. According to the bibliometric analysis results of keywords, we present a narrative summary of the potential mechanisms by which m6A regulates inflammation. The results showed that the key mechanisms by which m6A modulates inflammation include apoptosis, autophagy, oxidative stress, immune cell dysfunction, and dysregulation of signaling pathways.

Parainfectious cerebral vasculopathy complicating bacterial meningitis: Acute-short lived vasospasm followed by delayed-long lasting vasculitis

Bacterial meningitis is a serious, life-threatening infection of the meninges. Several radiological studies highlight prominent structural alterations occurring in the cerebral vasculature, leading to significant cerebrovascular consequences during bacterial meningitis. Beginning with reflexive arterial vasospasm , cerebrovascular disease during bacterial meningitis proceeds through a orderly sequence of arterial vasculitis with inflammatory cell infiltration, medial smooth muscle migration and proliferation, medial necrosis, adventitial fibrosis and eventual intimal stenosis. As such, this review focuses on changes occurring within cerebral arteries during disease progression, highlighting the various structural modifications occurring in the arterial vessels that contribute to disturbances in cerebral hemodynamics and, ultimately, cerebrovascular consequences during bacterial meningitis.

Early Assessment of Atherosclerotic Lesions and Vulnerable Plaques in vivo by Targeting Apoptotic Macrophages with AV Nanobubbles

Background

The early detection of atherosclerotic lesions is particularly important for risk prediction of acute cardiovascular events. Macrophages apoptosis was significantly associated with the degree of AS lesions and especially contributed to plaque vulnerability. In this research, we mainly sought to explore the feasibility of a home-made AV-nanobubbles (NB_AV) for visualization of apoptotic macrophages and assessment of atherosclerosis (AS) lesions by contrast-enhanced ultrasound (CEUS) imaging.

Methods

NB_AV were prepared by “Optimized Thin-Film Hydration” and “Biotin-Avidin-Biotin” methods. Then, the characterization and echogenicity of NB_AV were measured and analyzed in vitro. The targeting ability of NB_AV to ox-LDL–induced apoptotic macrophages was observed by laser scanning confocal microscope. The ApoE^−/− mice mode fed with high fat diet were observed by high-frequency ultrasound, microanatomy and oil red O staining. CEUS imaging in vivo was performed on AS plaques with NB_AV and NB_Ctrl injection through the tail vein in turn in ApoE^−/− mice. After CEUS imaging, the plaques were confirmed and analyzed by histopathological and immunological assessment.

Results

The prepared NB_AV had a nano-scale size distribution with a low PDI and a negative zeta potential. Moreover, NB_AV showed an excellent stability and exhibited a significantly echogenic signal than saline in vitro. In addition, we found that NB_AV could target apoptotic macrophages induced by ox-LDL. Compared with NB_Ctrl, CEUS imaging of NB_AV showed strong and sustained echo enhancement in plaque area of aortic arch in vivo. Further research showed that NB_AV sensitive plaques presented more significant pathological changes with several vulnerable plaque features and abundant TUNEL-positive area.

Conclusion

NB_AV displayed a sensitive indicator to evaluate apoptotic macrophages, indicating a promising CEUS molecular probe for AS lesions and vulnerable plaques identification.

Expanding role of deoxyribonucleic acid-sensing mechanism in the development of lifestyle-related diseases

In lifestyle-related diseases, such as cardiovascular, metabolic, respiratory, and kidney diseases, chronic inflammation plays a causal role in their pathogenesis; however, underlying mechanisms of sterile chronic inflammation are not well-understood. Previous studies have confirmed the damage of cells in these organs in the presence of various risk factors such as diabetes, dyslipidemia, and cigarette smoking, releasing various endogenous ligands for pattern recognition receptors. These studies suggested that nucleic acids released from damaged tissues accumulate in these tissues, acting as an endogenous ligand. Undamaged DNA is an integral factor for the sustenance of life, whereas, DNA fragments, especially those from pathogens, are potent activators of the inflammatory response. Recent studies have indicated that inflammatory responses such as the production of type I interferon (IFN) induced by DNA-sensing mechanisms which contributes to self-defense system in innate immunity participates in the progression of inflammatory diseases by the recognition of nucleic acids derived from the host, including mitochondrial DNA (mtDNA). The body possesses several types of DNA sensors. Toll-like receptor 9 (TLR9) recognizes DNA fragments in the endosomes. In addition, the binding of DNA fragments in the cytosol activates cyclic guanosine monophosphate (GMP)-adenosine monophosphate (AMP) synthase (cGAS), resulting in the synthesis of the second messenger cyclic GMP-AMP (cGAMP). The binding of cGAMP to stimulator of interferon genes (STING) activates NF-κB and TBK-1 signaling and consequently the production of many inflammatory cytokines including IFNs. Numerous previous studies have demonstrated the role of DNA sensors in self-defense through the recognition of DNA fragments derived from pathogens. Beyond the canonical role of TLR9 and cGAS-STING, this review describes the role of these DNA-sensing mechanism in the inflammatory responses caused by endogenous DNA fragments, and in the pathogenesis of lifestyle-related diseases.

Linear ubiquitination modification of NR6A1 by LUBAC inhibits RIPK3 kinase activity and attenuates apoptosis of vascular smooth muscle cells

Nuclear receptor subfamily 6 group A member 1 (NR6A1) is involved in promoting the apoptotic process of vascular smooth muscle cells (VSMCs) which is a critical process involved in atherosclerosis, but the action mechanism remains to be determined. Therefore, we studied the underlying mechanisms by which NR6A1 accelerated VSMC apoptosis in atherosclerosis. An atherosclerosis model has been established in apolipoprotein E-deficient rats with a high-fat diet for 12 weeks, which was characterized by pathological aortic plaques, increased lipid deposition and collagen content in aortic tissues, and high cholesterol and triglycerides levels in the serum. NR6A1 was experimentally shown to increase at protein level rather than messenger RNA level in atherosclerotic rats. Immunofluorescence exhibited the main location of NR6A1 in the cell nucleus of rat aortic tissues. By performing ectopic expression experiments, NR6A1 was demonstrated to suppress the viability and expedite the apoptosis of VSMCs, corresponding to augmented caspase-3, caspase-8, and caspase-9 activities. It was further unraveled that NR6A1 could activate receptor-interacting serine/threonine-protein kinase 3 (RIPK3) by inducing its phosphorylation. Conversely, RIPK3 inhibitor GSK872 undermined the proapoptotic effect of NR6A1 on VSMCs. The co-immunoprecipitation assay identified that linear ubiquitin chain assembly complex (LUBAC) can be pulled down by NR6A1. Furthermore. LUBAC inhibited the expression of NR6A1 by promoting its linear ubiquitination, thereby dephosphorylating RIPK3 and consequently inhibiting the VSMC apoptosis. Overall, LUBAC-induced linear ubiquitination of NR6A1 can potentially arrest the apoptosis of VSMCs in atherosclerosis by downregulating RIPK3 and attenuating caspase activity. This finding suggests promising athero-protective targets by limiting VSMC apoptosis.

Astragaloside IV protects against C/EBP homologous protein-mediated apoptosis in oxidized low-density lipoprotein-treated macrophages by promoting autophagy

Astragaloside Ⅳ (AS-Ⅳ) is one of the main active components extracted from Astragalus membranaceus that exerts an antiatherosclerotic effect. Our study explored the underlying anti-apoptotic effects and the mechanisms of action of AS-Ⅳ in oxidized low-density lipoprotein (oxLDL)-stimulated macrophages and in vulnerable plaques. The results showed that AS-Ⅳ lowered the oxLDL-induced lipid content and reversed the oxLDL-induced reduction in cell viability and elevation in lactate dehydrogenase (LDH) leakage and apoptosis in RAW264.7 macrophages, similar to the effects of 4-phenylbutyric acid (PBA, an ER stress inhibitor). In addition, consistent with the effect exerted by PBA, AS-Ⅳ inhibited oxLDL-triggered ER stress activation by decreasing the level of inositol-requiring enzyme1 phosphorylation and transcription factor 6 nuclear translocation and upregulating the protein and mRNA expression of glucose-regulated protein 78 (GPR78) and C/EBP homologous protein (CHOP). As expected, autophagy activation was induced by AS-IV, evidenced by increased expression of microtubule-associated protein 1 light chain 3-Ⅱ (LC3-Ⅱ), autophagy-related gene 5, and beclin-1 in macrophages. Furthermore, after pretreatment with 3-methyladenine and beclin-1 small interfering RNA, the inhibitory role played by AS-Ⅳ in oxLDL-induced ER stress-CHOP-mediated macrophage apoptosis was weakened, while its inhibitory effect was further enhanced by rapamycin pretreatment. Moreover, administration of AS-Ⅳ or rapamycin to Apoe^-/- mice upregulated LC3-Ⅱ expression and collagen content but decreased CHOP expression, macrophage apoptosis, and lipid areas. Overall, by promoting autophagy, AS-Ⅳ effectively protects macrophages from oxLDL-induced apoptosis mediated by ER stress-CHOP, which may reinforce the stability of atherosclerotic plaques.

Functional Investigation of Plant Growth Promoting Rhizobacterial Communities in Sugarcane

Plant microbiota are of great importance for host nutrition and health. As a C₄ plant species with a high carbon fixation capacity, sugarcane also associates with beneficial microbes, though mechanisms underlying sugarcane root-associated community development remain unclear. Here, we identify microbes that are specifically enriched around sugarcane roots and report results of functional testing of potentially beneficial microbes propagating with sugarcane plants. First, we analyzed recruitment of microbes through analysis of 16S rDNA enrichment in greenhouse cultured sugarcane seedlings growing in field soil. Then, plant-associated microbes were isolated and assayed for beneficial activity, first in greenhouse experiments, followed by field trials for selected microbial strains. The promising beneficial microbe SRB-109, which quickly colonized both roots and shoots of sugarcane plants, significantly promoted sugarcane growth in field trials, nitrogen and potassium acquisition increasing by 35.68 and 28.35%, respectively. Taken together, this report demonstrates successful identification and utilization of beneficial plant-associated microbes in sugarcane production. Further development might facilitate incorporation of such growth-promoting microbial applications in large-scale sugarcane production, which may not only increase yields but also reduce fertilizer costs and runoff.

Cordycepin Attenuates Palmitic Acid-Induced Inflammation and Apoptosis of Vascular Endothelial Cells through Mediating PI3K/Akt/eNOS Signaling Pathway

A well-known medicinal mushroom in the field of traditional Chinese medicine, Cordyceps sinensis, is a rare natural-occurring entomopathogenic fungus, and it typically grows at high altitudes on the plateau of the Himalayan. Previous studies indicated that cordycepin, the main bioactive chemical of Cordyceps sinensis, has very potent anticancer, anti-oxidant and anti-inflammatory activities. However, its protective effects against atherosclerotic changes in vascular endothelial cells have not been fully elucidated. In this study, we showed that pretreatment with cordycepin significantly attenuated palmitic acid (PA)-induced cytotoxicity, reactive oxygen species (ROS) generation, and inflammatory responses. We found that PA decreased phosphorylation of Akt, eNOS, and bioavailability of nitric oxide (NO), which in turn activated NF-[Formula: see text]B and the downstream inflammatory responses. All these detrimental events were markedly blocked by pretreatment with cordycepin. Moreover, cordycepin ameliorated destabilization of mitochondrial permeability, cytosolic calcium rises, and apoptotic features caused by PA. In addition, all these anti-inflammatory and anti-apoptosis effects of cordycepin were found to be inhibited by the PI3K and eNOS inhibitor, suggesting that its anti-atherosclerotic effects may partially be mediated by the PI3K/Akt/eNOS signaling pathway.

Development and characterization of viscoelastic polydimethylsiloxane phantoms for simulating arterial wall motion

Arterial wall viscoelasticity is likely to be a good diagnostic indicator of vascular disease, but only a few studies on the assessment of wall viscosity have been performed. Artery phantoms are manufactured using polydimethylsiloxane (PDMS) to simulate the viscoelastic characteristics of the artery wall, which depends on the wall tissue composition and progression of atherosclerosis. The viscoelastic property of PDMS is controlled by adjusting the mixture ratio of resin, curing agent, and pure silicone oil. The pressure and diameter waveforms of the artery phantom were measured to estimate the wall viscoelasticity. Elasticity is assessed using the diameter distention over the pulse pressure, and the viscosity is evaluated using the energy dissipation ratio of the pressure-diameter curve and the phase lag between the first harmonics of pressure and diameter waveforms (DP1). PDMS phantoms with resin-to-curing-agent ratios of 20:1 and 25:1 show viscoelastic characteristics similar to those of young and old human carotid arteries, respectively. Adding pure silicone oil further softens the silicone elastomer while decreasing its viscosity. The phantoms with 10:1:5 and 10:1:8 mixture ratios (resin: curing agent: silicone oil) show elasticity similar to that of the 20:1:0 and 25:1:0 ratios, respectively, albeit with a noticeable decrease in viscosity. An abrupt decrease in the phase lag (DP1) was found near the interface of the arterial phantom with different mixture ratios (20:1:0 and 10:1:5), while the change in diameter distension was negligible. DP1 may be a new index to differentiate wall tissues with similar elastic properties but different viscous behavior. The pressure diameter curve and DP1 of the phantom simulating the atherosclerosis wall can be compared with patient data and applied to clinical evaluation of plaque viscoelasticity. Computational analysis of arterial wall motion was performed using a standard linear viscoelastic model. The model parameters were determined from the measured pressure-diameter relationship, and the arterial wall motions of phantoms with different viscoelastic properties were successfully simulated. The computational model may provide a useful insight into the changes of arterial viscoelasticity caused by pathogenic wall degeneration.

Emerging roles of Toll-like receptor 9 in cardiometabolic disorders

Growing evidence suggests that damage-associated molecule patterns (DAMPs) and their receptors, pattern recognition receptors (PRRs), are associated with the progression of cardiometabolic disorders, including obesity-related insulin resistance and atherosclerosis. Cardiometabolic disorders share sterile chronic inflammation as a major cause; however, the exact mechanisms are still obscure. Toll-like receptor 9 (TLR9), one of the nucleic acid-sensing TLRs, recognizes DNA fragments derived from pathogens and contributes to self-defense by activation of the innate immune system. In addition, previous studies demonstrated that TLR9 recognizes DNA fragments released from host cells, accelerating sterile inflammation, which is associated with inflammatory diseases such as autoimmune diseases. In obese adipose tissue and atherosclerotic vascular tissue, various stresses release DNA fragments and/or nuclear proteins as DAMPs from degenerated adipocytes and vascular cells. Recent studies indicated that the activation of TLR9 in immune cells including macrophages and dendritic cells by recognition of these DAMPs promotes inflammation in these tissues, which causes cardiometabolic disorders. This review discusses recent advances in understanding the role of sterile inflammation associated with TLR9 and its endogenous ligands in cardiometabolic disorders. New insights into innate immunity may provide better understanding of cardiometabolic disorders and new therapeutic options for these major health threats in recent decades.

Toll-Like Receptor 9 Plays a Pivotal Role in Angiotensin II-Induced Atherosclerosis

Background Toll-like receptor ( TLR ) 9 recognizes bacterial DNA , activating innate immunity, whereas it also provokes inflammation in response to fragmented DNA released from mammalian cells. We investigated whether TLR 9 contributes to the development of vascular inflammation and atherogenesis using apolipoprotein E-deficient ( Apoe ^-/-) mice. Methods and Results Tlr9-deficient Apoe ^-/- ( Tlr9 ^-/- Apoe ^-/-) mice and Apoe ^-/- mice on a Western-type diet received subcutaneous angiotensin II infusion (1000 ng/kg per minute) for 28 days. Angiotensin II increased the plasma level of double-stranded DNA, an endogenous ligand of TLR 9, in these mice. Genetic deletion or pharmacologic blockade of TLR 9 in angiotensin II-infused Apoe ^-/- mice attenuated atherogenesis in the aortic arch ( P<0.05), reduced the accumulation of lipid and macrophages in atherosclerotic plaques, and decreased RNA expression of inflammatory molecules in the aorta with no alteration of metabolic parameters. On the other hand, restoration of TLR 9 in bone marrow in Tlr9 ^-/- Apoe ^-/- mice promoted atherogenesis in the aortic arch ( P<0.05). A TLR 9 agonist markedly promoted proinflammatory activation of Apoe ^-/- macrophages, partially through p38 mitogen-activated protein kinase signaling. In addition, genomic DNA extracted from macrophages promoted inflammatory molecule expression more effectively in Apoe ^-/- macrophages than in Tlr9 ^-/- Apoe ^-/- macrophages. Furthermore, in humans, circulating double-stranded DNA in the coronary artery positively correlated with inflammatory features of coronary plaques determined by optical coherence tomography in patients with acute myocardial infarction ( P<0.05). Conclusions TLR 9 plays a pivotal role in the development of vascular inflammation and atherogenesis through proinflammatory activation of macrophages. TLR 9 may serve as a potential therapeutic target for atherosclerosis.

Pathogenesis of atherosclerosis in the tunica intima, media, and adventitia of coronary arteries: An updated review

Atherosclerosis is a chronic inflammatory disease of arteries and it affects the structure and function of all three layers of the coronary artery wall. Current theories suggest that the dysfunction of endothelial cells is one of the initial steps in the development of atherosclerosis. The view that the tunica intima normally consists of a single layer of endothelial cells attached to the subendothelial layer and internal elastic membrane has been questioned in recent years. The structure of intima changes with age and it becomes multilayered due to migration of smooth muscle cells from the media to intima. At this stage, the migration and proliferation of smooth muscle cells do not cause pathological changes in the intima. The multilayering of intima is classically considered to be an important stage in the development of atherosclerosis, but in fact atherosclerotic plaques develop only focally due to the interplay of various processes that involve the resident and invading inflammatory cells. The tunica media consists of multiple layers of smooth muscle cells that produce the extracellular matrix, and this layer normally does not contain microvessels. During the development of atherosclerosis, the microvessels from the tunica adventitia or from the lumen may penetrate thickened media to provide nutrition and oxygenation. According to some theories, the endothelial dysfunction of these nutritive vessels may significantly contribute to the atherosclerosis of coronary arteries. The adventitia contains fibroblasts, progenitor cells, immune cells, microvessels, and adrenergic nerves. The degree of inflammatory cell infiltration into the adventitia, which can lead to the formation of tertiary lymphoid organs, correlates with the severity of atherosclerotic plaques. Coronary arteries are surrounded by perivascular adipose tissue that also participates in the atherosclerotic process.

Biglycan and atherosclerosis: Lessons from high cardiovascular risk conditions

Atherosclerosis (ATH) is a chronic, dynamic, evolutive process involving morphological and structural subversion of artery walls, leading to the formation of atherosclerotic plaques. ATH generally initiates during the childhood, occurring as a result of a number of changes in the intima tunica and in the media of arteries. A key event occurring during the pathobiology of ATH is the accumulation of lipoproteins in the sub-intimal spaces mediated by extracellular matrix (ECM) molecules, especially by the chondroitin sulfate/dermatan sulfate (CS/DS) -containing proteoglycans (CS/DSPGs). Among them, the proteoglycan biglycan (BGN) is critically involved in the onset and progression of ATH and evidences show that BGN represents the missing link between the pro-atherogenic status induced by both traditional and non-traditional cardiovascular risk factors and the development and progression of vascular damage. In the light of these findings, the role of BGN in dyslipidemia, hypertension, cigarette smoking, diabetes, chronic kidney disease and inflammatory status is briefly analyzed and discussed in order to shed new light on the underlying mechanisms governing the association between BGN and ATH.

Endothelial dysfunction induces atherosclerosis: increased aggrecan expression promotes apoptosis in vascular smooth muscle cells

Endothelial dysfunction-induced lipid retention is an early feature of atherosclerotic lesion formation. Apoptosis of vascular smooth muscle cells (VSMCs) is one of the major modulating factors of atherogenesis, which accelerates atherosclerosis progression by causing plaque destabilization and rupture. However, the mechanism underlying VSMC apoptosis mediated by endothelial dysfunction in relation to atherosclerosis remains elusive. In this study, we reveal differential expression of several genes related to lipid retention and apoptosis, in conjunction with atherosclerosis, by utilizing a genetic mouse model of endothelial nitric oxide synthase (eNOS) deficiency manifesting endothelial dysfunction. Moreover, eNOS deficiency led to the enhanced susceptibility against pro-apoptotic insult in VSMCs. In particular, the expression of aggrecan, a major proteoglycan, was elevated in aortic tissue of eNOS deficient mice compared to wild type mice, and administration of aggrecan induced apoptosis in VSMCs. This suggests that eNOS deficiency may elevate aggrecan expression, which promotes apoptosis in VSMC, thereby contributing to atherosclerosis progression. These results may facilitate the development of novel approaches for improving the diagnosis or treatment of atherosclerosis.

LncRNA GAS5 regulates vascular smooth muscle cell cycle arrest and apoptosis via p53 pathway

Vascular remodeling is a pathological process following cardiovascular intervention. Vascular smooth muscle cells (VSMC) play a critical role in the vascular remodeling. Long noncoding RNAs (lncRNA) are a class of gene regulators functioning through various mechanisms in physiological and pathological conditions. By using cultured VSMC and rat carotid artery balloon injury model, we found that lncRNA growth arrest specific 5 (GAS5) serves as a negative regulator for VSMC survival in vascular remodeling. By manipulating GAS5 expression via adenoviral overexpression or short hairpin RNA knockdown, we found that GAS5 suppresses VSMC proliferation while promoting cell cycle arrest and inducing cell apoptosis. Mechanistically, GAS5 directly binds to p53 and p300, stabilizes p53-p300 interaction, and thus regulates VSMC cell survival via induction of p53-downstream target genes. Importantly, local delivery of GAS5 via adenoviral vector suppresses balloon injury-induced neointima formation along with an increased expression of p53 and apoptosis in neointimal SMCs. Our study demonstrated for the first time that GAS5 negatively impacts VSMC survival via activation the p53 pathway during vascular remodeling.

A potential peptide derived from cytokine receptors can bind proinflammatory cytokines as a therapeutic strategy for anti-inflammation

Chronic inflammation is a pivotal event in the pathogenesis of cardiovascular diseases, including atherosclerosis, restenosis, and coronary artery disease. The efficacy of current treatment or preventive strategies for such inflammation is still inadequate. Thus, new anti-inflammatory strategies are needed. In this study, based on molecular docking and structural analysis, a potential peptide KCF18 with amphiphilic properties (positively charged and hydrophobic residues) derived from the receptors of proinflammatory cytokines was designed to inhibit cytokine-induced inflammatory response. Simulations suggested that KCF18 could bind to cytokines simultaneously, and electrostatic interactions were dominant. Surface plasmon resonance detection showed that KCF18 bound to both tumor necrosis factor-α (TNF-α) and interleukin-6, which is consistent with MM/PBSA binding free energy calculations. The cell experiments showed that KCF18 significantly reduced the binding of proinflammatory cytokines to their cognate receptors, suppressed TNF-α mRNA expression and monocyte binding and transmigration, and alleviated the infiltration of white blood cells in a peritonitis mouse model. The designed peptide KCF18 could remarkably diminish the risk of vascular inflammation by decreasing plasma cytokines release and by directly acting on the vascular endothelium. This study demonstrated that a combination of structure-based in silico design calculations, together with experimental measurements can be used to develop potential anti-inflammatory agents.

Evaluation of Collagen Fibers, MMP2, MMP9, 8-OHdG and Apoptosis in the Aorta of Ovariectomized LDL Knockout Mice Submitted to Aerobic Exercise

Background

In menopause, there is greater cellular exposure to oxidative stress, related to the decreased antioxidative effects of estrogen. These metabolic changes favor the progression of cardiovascular diseases, such as atherosclerosis. Abnormal function of the aorta - the most important artery - is associated with many cardiovascular diseases. Collagen, especially types I and III, is one of the most important aortic wall components and it can be affected by many factors, including menopause. The 8-OHdG is one of the main markers of DNA oxidative damage induced by reactive oxygen species (ROS).

Objective

We aimed to investigate effects of moderate aerobic training on the ascending aorta of LDL-knockout (LDL-KO) and ovariectomized female mice.

Methods

A total of 15 C57BL/6 mice and 15 LDL-KO mice were divided into experimental groups. The thickness and volume density of types I and III collagen fibers were performed by morphoquantitative analysis, whereas the MMP-2 and MMP-9 and 8-OHdG were detected by immunohistochemistry and apoptosis was detected by the TUNEL assay. The significance level for all tests was p < 0.05.

Results

Exercise causes an increase in the thickness of the aorta in LDL-KO groups, particularly accentuated in the ovariectomized groups. The type I collagen fibers showed an increase in volume density influenced by training in both Control groups and in the LDL-KO group. Type III collagen density decreased in both groups. The MMP-2 showed moderade immunostaining in the tunica media in LDL-KO groups, which did not occur in the control groups and the MMP-9 stained irregularly in all tissues. The marker 8-OhdG was stronger in the exercise training groups. Additionally, the ovariectomy, the exercise training and the LDL-KO treatments increased apoptosis.

Conclusion

These results suggest that moderate-intensity aerobic exercise in ovariectomized mice associated to an increase in LDL rate possibly increases oxidative stress and apoptosis induction.

Nutrition and Cardiovascular Health

Cardiovascular disease (CVD) is the leading cause of death in Western countries, representing almost 30% of all deaths worldwide. Evidence shows the effectiveness of healthy dietary patterns and lifestyles for the prevention of CVD. Furthermore, the rising incidence of CVD over the last 25 years has become a public health priority, especially the prevention of CVD (or cardiovascular events) through lifestyle interventions. Current scientific evidence shows that Western dietary patterns compared to healthier dietary patterns, such as the ‘Mediterranean diet’ (MeDiet), leads to an excessive production of proinflammatory cytokines associated with a reduced synthesis of anti-inflammatory cytokines. In fact, dietary intervention allows better combination of multiple foods and nutrients. Therefore, a healthy dietary pattern shows a greater magnitude of beneficial effects than the potential effects of a single nutrient supplementation. This review aims to identify potential targets (food patterns, single foods, or individual nutrients) for preventing CVD and quantifies the magnitude of the beneficial effects observed. On the other hand, we analyze the possible mechanisms implicated in this cardioprotective effect.

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.

Potential role of insulin receptor isoforms and IGF receptors in plaque instability of human and experimental atherosclerosis

BACKGROUND

Clinical complications associated with atherosclerotic plaques arise from luminal obstruction due to plaque growth or destabilization leading to rupture. We previously demonstrated that overexpression of insulin receptor isoform A (IRA) and insulin-like growth factor-I receptor (IGF-IR) confers a proliferative and migratory advantage to vascular smooth muscle cells (VSMCs) promoting plaque growth in early stages of atherosclerosis. However, the role of insulin receptor (IR) isoforms, IGF-IR or insulin-like growth factor-II receptor (IGF-IIR) in VSMCs apoptosis during advanced atherosclerosis remains unclear.

METHODS

We evaluated IR isoforms expression in human carotid atherosclerotic plaques by consecutive immunoprecipitations of insulin receptor isoform B (IRB) and IRA. Western blot analysis was performed to measure IGF-IR, IGF-IIR, and α-smooth muscle actin (α-SMA) expression in human plaques. The expression of those proteins, as well as the presence of apoptotic cells, was analyzed by immunohistochemistry in experimental atherosclerosis using BATIRKO; ApoE^-/- mice, a model showing more aggravated vascular damage than ApoE^-/- mice. Finally, apoptosis of VSMCs bearing IR (IRLoxP^+/+ VSMCs), or not (IR^-/- VSMCs), expressing IRA (IRA VSMCs) or expressing IRB (IRB VSMCs), was assessed by Western blot against cleaved caspase 3.

RESULTS

We observed a significant decrease of IRA/IRB ratio in human complicated plaques as compared to non-complicated regions. Moreover, complicated plaques showed a reduced IGF-IR expression, an increased IGF-IIR expression, and lower levels of α-SMA indicating a loss of VSMCs. In experimental atherosclerosis, we found a significant decrease of IRA with an increased IRB expression in aorta from 24-week-old BATIRKO; ApoE^-/- mice. Furthermore, atherosclerotic plaques from BATIRKO; ApoE^-/- mice had less VSMCs content and higher number of apoptotic cells. In vitro experiments showed that IGF-IR inhibition by picropodophyllin induced apoptosis in VSMCs. Apoptosis induced by thapsigargin was lower in IR^-/- VSMCs expressing higher IGF-IR levels as compared to IRLoxP^+/+ VSMCs. Finally, IRB VSMCs are more prone to thapsigargin-induced apoptosis than IRA or IRLoxP^+/+ VSMCs.

CONCLUSIONS

In advanced human atherosclerosis, a reduction of IRA/IRB ratio, decreased IGF-IR expression, or increased IGF-IIR may contribute to VSMCs apoptosis, promoting plaque instability and increasing the risk of plaque rupture and its clinical consequences.

Oxidative Stress-Mediated Atherosclerosis: Mechanisms and Therapies

Atherogenesis, the formation of atherosclerotic plaques, is a complex process that involves several mechanisms, including endothelial dysfunction, neovascularization, vascular proliferation, apoptosis, matrix degradation, inflammation, and thrombosis. The pathogenesis and progression of atherosclerosis are explained differently by different scholars. One of the most common theories is the destruction of well-balanced homeostatic mechanisms, which incurs the oxidative stress. And oxidative stress is widely regarded as the redox status realized when an imbalance exists between antioxidant capability and activity species including reactive oxygen (ROS), nitrogen (RNS) and halogen species, non-radical as well as free radical species. This occurrence results in cell injury due to direct oxidation of cellular protein, lipid, and DNA or via cell death signaling pathways responsible for accelerating atherogenesis. This paper discusses inflammation, mitochondria, autophagy, apoptosis, and epigenetics as they induce oxidative stress in atherosclerosis, as well as various treatments for antioxidative stress that may prevent atherosclerosis.

Endothelial cell-specific overexpression of developmental endothelial locus-1 does not influence atherosclerosis development in ApoE-/- mice

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

Epigallocatechin-3-gallate inhibits H2O2-induced apoptosis in Mouse Vascular Smooth Muscle Cells via 67kD Laminin Receptor

Epigallocatechin-3-gallate (EGCG) is one of the major polyphenolic compounds present in green tea extracts and has been used as a potential drug for the treatment of numerous diseases. The present study aimed to elucidate the role and mechanism of EGCG in protecting against H₂O₂-induced apoptosis in mouse vascular smooth muscle cells (VSMCs). VSMCs were pretreated with various concentrations of EGCG for 2 hours prior to treatment with H₂O₂. Treatment with H₂O₂ significantly decreased the cell viability and induced apoptosis of VSMCs, which were attenuated by pretreatment with EGCG. In particular, EGCG pretreatment significantly inhibited the H₂O₂-induced upregulation of cleaved forms of caspase-3, caspase-8, and caspase-9, Bax, CathepsinD, and downregulation of Bcl-2. Moreover, the antioxidation effect of EGCG on VSMCs was determined to be associated with the 67kD laminin receptor (67LR). Our results demonstrated that EGCG improved cell viability and protected VSMCs against oxidative stress through both extrinsic and intrinsic pathways, while 67LR is likely to be an active and key receptor of EGCG. These findings provide a novel molecular mechanism of EGCG in inhibiting H₂O₂-induced apoptosis in VSMCs, as well as its function in preventing the development of atherosclerosis.

Nuclear complex of glyceraldehyde-3-phosphate dehydrogenase and DNA repair enzyme apurinic/apyrimidinic endonuclease I protect smooth muscle cells against oxidant-induced cell death

Atherosclerotic plaque destabilization is the major determinant of most acute coronary events. Smooth muscle cell (SMC) death contributes to plaque destabilization. Here, we describe a novel antiapoptotic mechanism in vascular SMCs that involves interaction of nuclear glyceraldehyde-3-phosphate dehydrogenase (GAPDH) with apurinic/apyrimidinic endonuclease 1 (Ape1), the major oxidized DNA repair enzyme. GAPDH down-regulation potentiated H₂O₂-induced DNA damage and SMC apoptosis. Conversely, GAPDH overexpression decreased DNA damage and protected SMCs against apoptosis. Ape1 down-regulation reversed the resistance of GAPDH-overexpressing cells to DNA damage and apoptosis, which indicated that Ape1 is indispensable for GAPDH-dependent protective effects. GAPDH bound Ape1 in the SMC nucleus, and blocking (or oxidation) of GAPDH active site cysteines suppressed GAPDH/Ape1 interaction and potentiated apoptosis. GAPDH up-regulated Ape1 via a transcription factor homeobox protein Hox-A5-dependent mechanism. GAPDH levels were reduced in atherosclerotic plaque SMCs, and this effect correlated with oxidative stress and SMC apoptosis. Thus, we demonstrated that nuclear GAPDH/Ape1 interaction preserved Ape1 activity, reduced DNA damage, and prevented SMC apoptosis. Suppression of SMC apoptosis by maintenance of nuclear GAPDH/Ape1 interactions may be a novel therapy to increase atherosclerotic plaque stability.-Hou, X., Snarski, P., Higashi, Y., Yoshida, T., Jurkevich, A., Delafontaine, P., Sukhanov, S. Nuclear complex of glyceraldehyde-3-phosphate dehydrogenase and DNA repair enzyme apurinic/apyrimidinic endonuclease I protect smooth muscle cells against oxidant-induced cell death.

Toll-like receptor 4 mediates vascular remodeling in hyperhomocysteinemia

Although hyperhomocysteinemia (HHcy) is known to promote downstream pro-inflammatory cytokine elevation, the precise mechanism is still unknown. One of the possible receptors that could have significant attention in the field of hypertension is toll-like receptor 4 (TLR-4). TLR-4 is a cellular membrane protein that is ubiquitously expressed in all cell types of the vasculature. Its mutation can attenuate the effects of HHcy-mediated vascular inflammation and mitochondria- dependent cell death that suppresses hypertension. In this review, we observed that HHcy induces vascular remodeling through immunological adaptation, promoting inflammatory cytokine up-regulation (IL-1β, IL-6, TNF-α) and initiation of mitochondrial dysfunction leading to cell death and chronic vascular inflammation. The literature suggests that HHcy promotes TLR-4-driven chronic vascular inflammation and mitochondria-mediated cell death inducing peripheral vascular remodeling. In the previous studies, we have characterized the role of TLR-4 mutation in attenuating vascular remodeling in hyperhomocysteinemia. This review includes, but is not limited to, the physiological synergistic aspects of the downstream elevation of cytokines found within the vascular inflammatory cascade. These events subsequently induce mitochondrial dysfunction defined by excessive mitochondrial fission and mitochondrial apoptosis contributing to vascular remodeling followed by hypertension.

DNA damage-dependent mechanisms of ageing and disease in the macro- and microvasculature

A decline in the function of the macro- and micro-vasculature occurs with ageing. DNA damage also accumulates with ageing, and thus DNA damage and repair have important roles in physiological ageing. Considerable evidence also supports a crucial role for DNA damage in the development and progression of macrovascular disease such as atherosclerosis. These findings support the concept that prolonged exposure to risk factors is a major stimulus for DNA damage within the vasculature, in part via the generation of reactive oxygen species. Genomic instability can directly affect vascular cellular function, leading to cell cycle arrest, apoptosis and premature vascular cell senescence. In contrast, the study of age-related impaired function and DNA damage mechanisms in the microvasculature is limited, although ageing is associated with microvessel endothelial dysfunction. This review examines current knowledge on the role of DNA damage and DNA repair systems in macrovascular disease such as atherosclerosis and microvascular disease. We also discuss the cellular responses to DNA damage to identify possible strategies for prevention and treatment.

Protective effects of Semiaquilegia adoxoides n-butanol extract against hydrogen peroxide-induced oxidative stress in human lens epithelial cells

Context Hydrogen peroxide (H2O2)-induced damage in the lens epithelium leads to cell death and cataract. Semiaquilegia adoxoides (DC.) Makino (Ranunculaceae), a folk medicine of Hmong (an ethnic group of China), has been traditionally used to treat cataract; however, the underlying molecular mechanism is yet to be uncovered. Objective This study aimed to investigate whether the n-butanol extract of S. adoxoides (nSA) is effective against the H2O2-induced oxidative stress in human lens epithelial (HLE) cells. Materials and methods Human lens epithelial (SRA 01/04) cells were stimulated by H2O2 (250 μM) in the presence or absence of nSA. The antioxidant effects of nSA were determined in terms of cell viability (MTT assay), apoptosis (AnnexinV/PI staining), radical scavenging capability (various enzymatic assays), loss of mitochondrial membrane potential (Rhodamine 123 staining), expression of apoptotic markers including caspase-3 and caspase-9 and the change of Bcl-2/Bax ratio (western blot) in the HLE cells. Results The results showed that pretreatment of nSA (250, 500 and 1000 μg/mL) markedly reduced H2O2-induced cellular apoptosis and malondialdehyde accumulation, but elevated the activities of total superoxide dismutase, catalase, glutathione peroxidase. Thus, the total antioxidative capability was enhanced upon the nSA treatment meanwhile the loss of mitochondrial membrane potential was prevented. Moreover, nSA at concentrations of 250, 500 and 1000 μg/mL also significantly suppressed the activation of caspase-3 and -9, and increased the Bcl-2/Bax ratio in the HLE cells. Discussion and conclusion Our findings suggested that nSA is a potential prophylactic agent in the prevention of cataractogeneis.

Leukocytes Link Local and Systemic Inflammation in Ischemic Cardiovascular Disease: An Expanded "Cardiovascular Continuum"

Physicians have traditionally viewed ischemic heart disease in a cardiocentric manner: plaques grow in arteries until they block blood flow, causing acute coronary and other ischemic syndromes. Recent research provides new insight into the integrative biology of inflammation as it contributes to ischemic cardiovascular disease. These results have revealed hitherto unsuspected inflammatory signaling networks at work in these disorders that link the brain, autonomic nervous system, bone marrow, and spleen to the atherosclerotic plaque and to the infarcting myocardium. A burgeoning clinical published data indicates that such inflammatory networks-far from a mere laboratory curiosity-operate in our patients and can influence aspects of ischemic cardiovascular disease that determine decisively clinical outcomes. These new findings enlarge the circle of the traditional "cardiovascular continuum" beyond the heart and vessels to include the nervous system, the spleen, and the bone marrow.

In vitro and in silico analysis of the vascular effects of asymmetrical N,N-bis(alkanol)amine aryl esters, novel multidrug resistance-reverting agents

Asymmetrical N,N-bis(alkanol)amine aryl esters (FRA77, GDE6, and GDE19) are potent multidrug resistance (MDR) reversers. Their structures loosely remind that of the Ca(2+) antagonist verapamil. Therefore, the aim of this study was to investigate their vascular activity in vitro. Their effects on the mechanical activity of fresh and cultured rat aorta rings on Cav1.2 channel current (I Ca1.2) of A7r5 cells and their cytotoxicity on A7r5 and EA.hy926 cells were analyzed. Docking at the rat α1C subunit of the Cav1.2 channel was simulated in silico. Compounds tested were cytotoxic at concentrations >1 μM (FRA77, GDE6, GDE19) and >10 μM (verapamil) in EA.hy926 cells, or >10 μM (FRA77, GDE6, GDE19) and at 100 μM (verapamil) in A7r5 cells. In fresh rings, the three compounds partly antagonized phenylephrine and 60 mM K(+) (K60)-induced contraction at concentrations ≥1 and ≥3 μM, respectively. On the contrary, verapamil fully relaxed rings pre-contracted with both agents. In cultured rings, 10 μM GDE6, GDE19, FRA77, and verapamil significantly reduced the contractile response to both phenylephrine and K60. Similarly to verapamil, the three compounds docked at the α1C subunit, interacting with the same amino acids residues. FRA77, GDE6, and GDE19 inhibited I Ca1.2 with IC50 values 1 order of magnitude higher than that of verapamil. FRA77-, GDE6-, and GDE19-induced vascular effects occurred at concentrations that are at least 1 order of magnitude higher than those effectively reverting MDR. Though an unambiguous divergence between MDR reverting and vascular activity is of overwhelming importance, these findings consistently contribute to the design and synthesis of novel and potent chemosensitizers.

Factors Associated with Apoptosis in Symptomatic and Asymptomatic Carotid Atherosclerotic Plaques

The aim of this study was to investigate the differences that are present between apoptosis in symptomatic (with symptoms of cerebral ischemic attack) and asymptomatic carotid atherosclerotic plaques. The apoptotic process in macrophages and smooth muscle cells was evaluated. Cellular markers and products of immune cells in symptomatic and asymptomatic atherosclerotic plaque and endoarterectomy specimen were analyzed by immunohistochemistry. No statistically significant differences were present regarding the mean SMC actin-positive area. Using double staining of α-smooth muscle actin and TUNEL techniques, the number of smooth muscle cells in apoptosis was statistically higher in symptomatic plaque as compared with asymptomatic plaque. Statistically significant differences (p=0.009) were also found in the CD45-positive cells in the inflammatory infiltrate. The CD68-positive macrophages showed statistically significant differences (p=0.0001). Similarly, the double staining with CD68 and TUNEL revealed that apoptotic macrophages were mainly present in asymptomatic plaques rather than symptomatic plaques. Statistically significant differences (p<0.001) were found in the Bcl-2 expression, with higher values in asymptomatic plaques. Our data showed that the increase of the inflammatory cells contributes to plaque instability and that death due to apoptosis of smooth muscle cells in symptomatic plaques could contribute to their destabilization and explains their tendency to fracture.

beta-Naphthoflavone protects from peritonitis by reducing TNF-alpha-induced endothelial cell activation

β-Naphthoflavone (β-NF), a ligand of the aryl hydrocarbon receptor, has been shown to possess anti-oxidative properties. We investigated the anti-oxidative and anti-inflammatory potential of β-NF in human microvascular endothelial cells treated with tumor necrosis factor-alpha (TNF-α). Pretreatment with β-NF significantly inhibited TNF-α-induced intracellular reactive oxygen species, translocation of p67(phox), and TNF-α-induced monocyte binding and transmigration. In addition, β-NF significantly inhibited TNF-α-induced ICAM-1 and VCAM-1 expression. The mRNA expression levels of the inflammatory cytokines TNF-α and IL-6 were reduced by β-NF, as was the infiltration of white blood cells, in a peritonitis model. The inhibition of adhesion molecules was associated with suppressed nuclear translocation of NF-κB p65 and Akt, and suppressed phosphorylation of ERK1/2 and p38. The translocation of Egr-1, a downstream transcription factor involved in the MEK-ERK signaling pathway, was suppressed by β-NF treatment. Our findings show that β-NF inhibits TNF-α-induced NF-kB and ERK1/2 activation and ROS generation, thereby suppressing the expression of adhesion molecules. This results in reduced adhesion and transmigration of leukocytes in vitro and prevents the infiltration of leukocytes in a peritonitis model. Our findings also suggest that β-NF might prevent TNF-α-induced inflammation.

Variability in vascular smooth muscle cell stretch-induced responses in 2D culture

The pulsatile nature of blood flow exposes vascular smooth muscle cells (VSMCs) in the vessel wall to mechanical stress, in the form of circumferential and longitudinal stretch. Cyclic stretch evokes VSMC proliferation, apoptosis, phenotypic switching, migration, alignment, and vascular remodeling. Given that these responses have been observed in many cardiovascular diseases, a defined understanding of their underlying mechanisms may provide critical insight into the pathophysiology of cardiovascular derangements. Cyclic stretch-triggered VSMC responses and their effector mechanisms have been studied in vitro using tension systems that apply either uniaxial or equibiaxial stretch to cells grown on an elastomer-bottomed culture plate and ex vivo by stretching whole vein segments with small weights. This review will focus mainly on VSMC responses to the in vitro application of mechanical stress, outlining the inconsistencies in acquired data, and comparing them to in vivo or ex vivo findings. Major discrepancies in data have been seen in mechanical stress-induced proliferation, apoptosis, and phenotypic switching responses, depending on the stretch conditions. These discrepancies stem from variations in stretch conditions such as degree, axis, duration, and frequency of stretch, wave function, membrane coating, cell type, cell passage number, culture media content, and choice of in vitro model. Further knowledge into the variables that cause these incongruities will allow for improvement of the in vitro application of cyclic stretch.

Natural progression of atherosclerosis from pathologic intimal thickening to late fibroatheroma in human coronary arteries: A pathology study

OBJECTIVE

Smooth muscle cells, macrophage infiltration and accumulation of lipids, proteoglycans, collagen matrix and calcification play a central role in atherosclerosis. The early histologic changes of plaque progression from pathologic intimal thickenings (PIT) to late fibroatheroma lesions have not been fully characterized.

METHODS

A total of 151 atherosclerotic coronary lesions were collected from 67 sudden death victims. Atherosclerotic plaques were classified as PIT without macrophage infiltration, PIT with macrophages, and early and late fibroatheromas. Presence of macrophages and proteoglycans (versican, decorin and biglycan) were recognized by specific antibodies while hyaluronan was detected by affinity histochemistry. Lipid deposition was identified by oil-red-O, and calcification was assessed following von Kossa and alizarin red staining.

RESULTS

Lesion progression from PIT to late fibroatheroma was associated with increase in macrophage accumulation (p < 0.001) and decreasing apoptotic body clearance by macrophages (ratio of engulfed-to-total apoptotic bodies) (p < 0.001). Lipid deposition in lipid pool of PIT had a microvesicular appearance whereas those in the necrotic core were globular in nature. Overall, the accumulation of hyaluronan (p < 0.001), and proteoglycan versican (p < 0.001) and biglycan (p = 0.013) declined along with lesion progression from PIT to fibroatheromas. Microcalcification was first observed only within areas of lipid pools and its presence and size increased in lesions with necrotic core.

CONCLUSIONS

PIT to fibroatheroma lesions are accompanied by early lipid accumulation, followed by macrophage infiltration with defective clearance of apoptotic bodies along with decrease in proteoglycan and hyaluronan in lipid pools that convert to necrotic cores. Calcification starts in PIT and increases with plaque progression.

D4F alleviates macrophage-derived foam cell apoptosis by inhibiting CD36 expression and ER stress-CHOP pathway

This study was designed to explore the protective effect of D4F, an apoA-I mimetic peptide, on oxidized LDL (ox-LDL)-induced endoplasmic reticulum (ER) stress-CCAAT/enhancer-binding protein (C/EBP) homologous protein (CHOP) pathway-mediated apoptosis in macrophages. Our results showed that treating apoE knockout mice with D4F decreased the serum ox-LDL level and apoptosis in atherosclerotic lesions with concomitant downregulation of cluster of differentiation 36 (CD36) and inhibition of ER stress. In vitro, D4F inhibited macrophage-derived foam cell formation. Furthermore, like ER stress inhibitor 4-phenylbutyric acid (PBA), D4F inhibited ox-LDL- or tunicamycin (TM, an ER stress inducer)-induced reduction in cell viability and increase in lactate dehydrogenase leakage, caspase-3 activation, and apoptosis. Additionally, like PBA, D4F inhibited ox-LDL- or TM-induced activation of ER stress response as assessed by the reduced nuclear translocation of activating transcription factor 6 and the decreased phosphorylation of protein kinase-like ER kinase and eukaryotic translation initiation factor 2α, as well as the downregulation of glucose-regulated protein 78 and CHOP. Moreover, D4F mitigated ox-LDL uptake by macrophages and CD36 upregulation induced by ox-LDL or TM. These data indicate that D4F can alleviate the formation and apoptosis of macrophage-derived foam cells by suppressing CD36-mediated ox-LDL uptake and subsequent activation of the ER stress-CHOP pathway.

miR-155 inhibits oxidized low-density lipoprotein-induced apoptosis of RAW264.7 cells

Macrophage apoptosis is a prominent feature of advanced atherosclerotic plaques. Here, we examined the hypothesis that the apoptotic machinery is regulated by microRNA-155 (miR-155). Constitutive expression of miR-155 was detected in RAW264.7 cells, which was increased following stimulation with oxidized low-density lipoprotein (OxLDL) in a dose- and time-dependent manner. OxLDL-treated RAW264.7 cells showed a marked time- and dose-dependent increase in apoptosis, which was suppressed in the presence of mimics and increased with antagonists of miR-155. Bioinformatics analysis revealed Fas-associated death domain-containing protein (FADD) as a putative target of miR-155. Luciferase reporter assay and Western blot further disclosed that miR-155 inhibits FADD expression by directly targeting the 3'-UTR region. We propose that miR-155 attenuates the macrophage apoptosis, at least in part, through FADD regulation, since forced expression of FADD blocked the ability of miR-155 to inhibit apoptosis. Our results collectively suggest that miR-155 attenuates apoptosis of OxLDL-mediated RAW264.7 cells by targeting FADD, supporting a possible therapeutic role in atherosclerosis.

Echo-computed tomography strain imaging of healthy and diseased carotid specimens

To improve our understanding of the mechanical behavior of human atherosclerotic plaque tissue, fully 3-D geometrical, morphological and dynamical information is essential. For this purpose, four-dimensional (3-D+t) strain imaging using an ultrasound tomography approach (echo-computed tomography) was performed in carotid arteries in vitro. The method was applied to a carotid phantom (CPh), a porcine carotid artery (PC) and human carotid atherosclerotic plaque samples (HC, n = 5). Each sample was subjected to an intraluminal pressure, after which 2-D longitudinal ultrasound images were obtained for 36 angles along the circumferential direction. Local deformations were estimated using a 2-D strain algorithm, and 3-D radial strain data were reconstructed. At systole, median luminal strains of 15% (CPh) and 18% (PC) were found, which is in agreement with the stiffness of the material and applied pressure pulse. The elastographic signal-to-noise ratio was consistent in all directions and ranged from 16 to 36 dB. Furthermore, realistic but more complex strain patterns were found for the HC, with 99th percentile systolic strain values ranging from 0.1% to 18%.

Raised soluble P-selectin moderately accelerates atherosclerotic plaque progression

Soluble P-selectin (sP-selectin), a biomarker of inflammatory related pathologies including cardiovascular and peripheral vascular diseases, also has pro-atherosclerotic effects including the ability to increase leukocyte recruitment and modulate thrombotic responses in vivo. The current study explores its role in progressing atherosclerotic plaque disease. Apoe^−/− mice placed on a high fat diet (HFD) were given daily injections of recombinant dimeric murine P-selectin (22.5 µg/kg/day) for 8 or 16 weeks. Saline or sE-selectin injections were used as negative controls. In order to assess the role of sP-selectin on atherothrombosis an experimental plaque remodelling murine model, with sm22α-hDTR Apoe^−/− mice on a HFD in conjunction with delivery of diphtheria toxin to induce targeted vascular smooth muscle apoptosis, was used. These mice were similarly given daily injections of sP-selectin for 8 or 16 weeks. While plaque mass and aortic lipid content did not change with sP-selectin treatment in Apoe^−/− or SM22α-hDTR Apoe^−/− mice on HFD, increased plasma MCP-1 and a higher plaque CD45 content in Apoe^−/− HFD mice was observed. As well, a significant shift towards a more unstable plaque phenotype in the SM22α-hDTR Apoe^−/− HFD mice, with increased macrophage accumulation and lower collagen content, leading to a lower plaque stability index, was observed. These results demonstrate that chronically raised sP-selectin favours progression of an unstable atherosclerotic plaque phenotype.

Haptoglobin genotype-dependent differences in macrophage lysosomal oxidative injury

The major function of the Haptoglobin (Hp) protein is to control trafficking of extracorpuscular hemoglobin (Hb) thru the macrophage CD163 receptor with degradation of the Hb in the lysosome. There is a common copy number polymorphism in the Hp gene (Hp 2 allele) that has been associated with a severalfold increased incidence of atherothrombosis in multiple longitudinal studies. Increased plaque oxidation and apoptotic markers have been observed in Hp 2-2 atherosclerotic plaques, but the mechanism responsible for this finding has not been determined. We proposed that the increased oxidative injury in Hp 2-2 plaques is due to an impaired processing of Hp 2-2-Hb complexes within macrophage lysosomes, thereby resulting in redox active iron accumulation, lysosomal membrane oxidative injury, and macrophage apoptosis. We sought to test this hypothesis in vitro using purified Hp-Hb complex and cells genetically manipulated to express CD163. CD163-mediated endocytosis and lysosomal degradation of Hp-Hb were decreased for Hp 2-2-Hb complexes. Confocal microscopy using lysotropic pH indicator dyes demonstrated that uptake of Hp 2-2-Hb complexes disrupted the lysosomal pH gradient. Cellular fractionation studies of lysosomes isolated from macrophages incubated with Hp 2-2-Hb complexes demonstrated increased lysosomal membrane oxidation and a loss of lysosomal membrane integrity leading to lysosomal enzyme leakage into the cytoplasm. Additionally, markers of apoptosis, DNA fragmentation, and active caspase 3 were increased in macrophages that had endocytosed Hp 2-2-Hb complexes. These data provide novel mechanistic insights into how the Hp genotype regulates lysosomal oxidative stress within macrophages after receptor-mediated endocytosis of Hb.

Oxidized phospholipids induce ceramide accumulation in RAW 264.7 macrophages: role of ceramide synthases

Oxidized phospholipids (OxPLs), including 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphocholine (PGPC) and 1-palmitoyl-2-oxovaleroyl-sn-glycero-3-phosphocholine (POVPC) are among several biologically active derivatives that are generated during oxidation of low-density lipoproteins (LDLs). These OxPLs are factors contributing to pro-atherogenic effects of oxidized LDLs (OxLDLs), including inflammation, proliferation and death of vascular cells. OxLDL also elicits formation of the lipid messenger ceramide (Cer) which plays a pivotal role in apoptotic signaling pathways. Here we report that both PGPC and POVPC are cytotoxic to cultured macrophages and induce apoptosis in these cells which is associated with increased cellular ceramide levels after several hours. In addition, exposure of RAW 264.7 cells to POVPC and PGPC under the same conditions resulted in a significant increase in ceramide synthase activity, whereas, acid or neutral sphingomyelinase activities were not affected. PGPC is not only more toxic than POVPC, but also a more potent inducer of ceramide formation by activating a limited subset of CerS isoforms. The stimulated CerS activities are in line with the C16-, C22-, and C24:0-Cer species that are generated under the influence of the OxPL. Fumonisin B1, a specific inhibitor of CerS, suppressed OxPL-induced ceramide generation, demonstrating that OxPL-induced CerS activity in macrophages is responsible for the accumulation of ceramide. OxLDL elicits the same cellular ceramide and CerS effects. Thus, it is concluded that PGPC and POVPC are active components that contribute to the capacity of this lipoprotein to elevate ceramide levels in macrophages.

The Rho/Rho-associated protein kinase inhibitor fasudil in the protection of endothelial cells against advanced glycation end products through the nuclear factor κB pathway

Accumulating evidence has demonstrated that the Rho/Rho-associated protein kinase (Rho/ROCK) and nuclear factor κB (NF-κB) signaling pathways are involved in the pathogenesis of diabetic vascular injury. In this study, we investigated the beneficial effects of fasudil, a ROCK inhibitor, on vascular endothelial injury induced by advanced glycation end products (AGEs) in vitro. Human umbilical vein endothelial cells (HUVECs) were stimulated with AGEs and AGEs plus fasudil in various concentrations for different time periods. Monocyte-endothelial cell adhesion, vascular cell adhesion molecule-1 (VCAM-1) and monocyte chemoattractant protein-1 (MCP-1) expression, protein expression and activation of Rho/ROCK, activation of NF-κB and reactive oxygen species (ROS) production were evaluated. Fasudil suppressed AGE-induced monocyte-endothelial adhesion. Fasudil also reduced the mRNA and protein expression of VCAM-1 and MCP-1 in a concentration- and time-dependent manner. Moreover, increases in the protein levels of Rho/ROCK and ROCK activity mediated by AGEs were inhibited by the addition of fasudil. Additionally, fasudil attenuated AGE-induced NF-κB-dependent transcriptional activity and inhibition of NF-κB (IκB) phosphorylation. ROS production induced by AGEs was also reduced by fasudil in HUVECs. The results suggest that ROCK inhibition may protect the vascular endothelium against AGE-induced monocyte-endothelial adhesion in vitro through the reduction of ROS generation and the downregulation of NF-κB signaling. Thus, ROCK inhibition may be a novel therapeutic approach for the treatment of vascular complications in diabetes.

Utilizing imaging tools in lipidology: examining the potential of MRI for monitoring cholesterol therapy

Lipid abnormalities play important roles in the development of atherosclerosis. Lipid therapies result in alterations in atherosclerotic plaques including halting of progression of the plaque, lipid transport out of the plaque and reducing inflammatory activity, which lead to plaque morphologies that are less prone to disruption, the main cause of clinical events. In order to investigate and monitor plaque morphological changes during lipid therapy in vivo we need an imaging method that can provide accurate assessment of plaque tissue components and activity. MRI of atherosclerosis has been validated as a reliable assessment of the size of the vessel lumen, but also the size of the plaque, its tissue composition and plaque activity, including inflammation. The purpose of this review is to summarize the state of evidence for the direct assessment of atherosclerotic plaque and its change by MRI, and to establish the proven role of MRI of atherosclerosis in pharmaceutical trials with lipid therapy.

Viral cross-class serpin inhibits vascular inflammation and T lymphocyte fratricide; a study in rodent models in vivo and human cell lines in vitro

Poxviruses express highly active inhibitors, including serine proteinase inhibitors (serpins), designed to target host immune defense pathways. Recent work has demonstrated clinical efficacy for a secreted, myxomaviral serpin, Serp-1, which targets the thrombotic and thrombolytic proteases, suggesting that other viral serpins may have therapeutic application. Serp-2 and CrmA are intracellular cross-class poxviral serpins, with entirely distinct functions from the Serp-1 protein. Serp-2 and CrmA block the serine protease granzyme B (GzmB) and cysteine proteases, caspases 1 and 8, in apoptotic pathways, but have not been examined for extracellular anti-inflammatory activity. We examined the ability of these cross-class serpins to inhibit plaque growth after arterial damage or transplant and to reduce leukocyte apoptosis. We observed that purified Serp-2, but not CrmA, given as a systemic infusion after angioplasty, transplant, or cuff-compression injury markedly reduced plaque growth in mouse and rat models in vivo. Plaque growth was inhibited both locally at sites of surgical trauma, angioplasty or transplant, and systemically at non-injured sites in ApoE-deficient hyperlipidemic mice. With analysis in vitro of human cells in culture, Serp-2 selectively inhibited T cell caspase activity and blocked cytotoxic T cell (CTL) mediated killing of T lymphocytes (termed fratricide). Conversely, both Serp-2 and CrmA inhibited monocyte apoptosis. Serp-2 inhibitory activity was significantly compromised either in vitro with GzmB antibody or in vivo in ApoE/GzmB double knockout mice. Conclusions The viral cross-class serpin, Serp-2, that targets both apoptotic and inflammatory pathways, reduces vascular inflammation in a GzmB-dependent fashion in vivo, and inhibits human T cell apoptosis in vitro. These findings indicate that therapies targeting Granzyme B and/or T cell apoptosis may be used to inhibit T lymphocyte apoptosis and inflammation in response to arterial injury.