Atherosclerotic Plaque Instability Research Articles

Inverse J-shaped relation between coronary arterial calcium density and mortality in advanced chronic kidney disease.

The coronary artery calcium (CAC) score from cardiac computed tomography (CT) is a composite of CAC volume and CAC density. In the general population, CAC volume is positively and CAC density inversely associated with cardiovascular disease (CVD) events, implying that decreased CAC density reflects atherosclerotic plaque instability. We analysed associations of CAC indices with mortality risk in patients with end-stage renal disease [chronic kidney disease Stage 5 (CKD5)]. In 296 CKD5 patients undergoing cardiac CT (median age 55 years, 67% male, 19% diabetes, 133 dialysed), the Framingham risk score (FRS), presence of CVD and protein-energy wasting (PEW; subjective global assessment) and high-sensitivity C-reactive protein (hsCRP) and interleukin-6 (IL-6) were determined at baseline. During follow-up for a median of 35 months, 51 patients died and 75 patients underwent renal transplantation. All-cause mortality risk was analysed with competing-risk regression models. Vascular calcification was analysed in biopsies of the arteria epigastrica inferior in 111 patients. Patients in the middle tertile of CAC density had the highest CAC score, CAC volume, age, CVD, PEW, FRS, hsCRP and IL-6. In competing risk analysis, the middle {subhazard ratio [sHR] 10.7 [95% confidence interval (CI) 2.0-57.3]} and high [sHR 8.9 (95% CI 1.5-51.8)] tertiles of CAC density associated with increased mortality, independent of CAC volume. The high tertile of CAC volume, independent of CAC density, associated with increased mortality [sHR 8.9 (95% CI 1.5-51.8)]. Arterial media calcification was prominent and associated with CAC volume and CAC density. In CKD5, mortality increased linearly with higher CAC score and CAC volume whereas for CAC density an inverse J-shaped pattern was observed, with the crude mortality rate being highest for the middle tertile of CAC density. CAC volume and CAC density were associated with the extent of arterial media calcification.

Early Prognostic Value of High-Sensitivity Troponin T after Coronary Artery Bypass Grafting.

Periprocedural myocardial injury after coronary artery bypass grafting (CABG) may affect the patient's prognosis and may be due to a different set of factors beyond the atherosclerotic plaque instability. Considering the challenges in the diagnosis of myocardial injury after CABG, the aim of this study was to determine the association between postoperative early elevation of high-sensitivity troponin T (hsTnT) and all-cause 30-day mortality after CABG. We enrolled 600 consecutive patients who underwent CABG. The hsTnT value was measured immediately before surgery and in the morning of the first postoperative day. The baseline hsTnT was 13 ng/L (7-26 ng/L) and 273 patients (45.7%) had baseline hsTnT above the 99th percentile/upper reference limit (URL) (14 ng/L). The median for hsTnT at first postoperative day was 235 ng/L (152-425 ng/L). We calculated the postoperative hsTnT ratio to URL for each patient, representing the number of times exceeding the URL (hsTnT value divided by 14 ng/L). The multivariate analysis by Cox proportional hazard model revealed that age (years) (hazard ratio [HR] = 1.13, 95% confidence interval [CI]: 1.07-1.20; p < 0.001) and postoperative hsTnT ratio to URL (per 10-fold increase) (HR = 1.06, 95% CI: 1.04-1.08; p < 0.001) were independent predictors of all-cause 30-day mortality after CABG. In our series, age and higher postoperative hsTnT levels were independent and reliable predictors of all-cause 30-day mortality after CABG.

Targeting epigenetics and non-coding RNAs in atherosclerosis: from mechanisms to therapeutics.

Atherosclerosis, the principal cause of cardiovascular death worldwide, is a pathological disease characterized by fibro-proliferation, chronic inflammation, lipid accumulation, and immune disorder in the vessel wall. As the atheromatous plaques develop into advanced stage, the vulnerable plaques are prone to rupture, which causes acute cardiovascular events, including ischemic stroke and myocardial infarction. Emerging evidence has suggested that atherosclerosis is also an epigenetic disease with the interplay of multiple epigenetic mechanisms. The epigenetic basis of atherosclerosis has transformed our knowledge of epigenetics from an important biological phenomenon to a burgeoning field in cardiovascular research. Here, we provide a systematic and up-to-date overview of the current knowledge of three distinct but interrelated epigenetic processes (including DNA methylation, histone methylation/acetylation, and non-coding RNAs), in atherosclerotic plaque development and instability. Mechanistic and conceptual advances in understanding the biological roles of various epigenetic modifiers in regulating gene expression and functions of endothelial cells (vascular homeostasis, leukocyte adhesion, endothelial-mesenchymal transition, angiogenesis, and mechanotransduction), smooth muscle cells (proliferation, migration, inflammation, hypertrophy, and phenotypic switch), and macrophages (differentiation, inflammation, foam cell formation, and polarization) are discussed. The inherently dynamic nature and reversibility of epigenetic regulation, enables the possibility of epigenetic therapy by targeting epigenetic "writers", "readers", and "erasers". Several Food Drug Administration-approved small-molecule epigenetic drugs show promise in pre-clinical studies for the treatment of atherosclerosis. Finally, we discuss potential therapeutic implications and challenges for future research involving cardiovascular epigenetics, with an aim to provide a translational perspective for identifying novel biomarkers of atherosclerosis, and transforming precision cardiovascular research and disease therapy in modern era of epigenetics.

Aldehyde dehydrogenase 2 deficiency promotes atherosclerotic plaque instability through accelerating mitochondrial ROS-mediated vascular smooth muscle cell senescence

Previous evidence has indicated a beneficial role for aldehyde dehydrogenase 2 (ALDH2) in suppressing atherosclerotic plaque progression and instability. However, the underlying mechanism remains somewhat elusive. This study was designed to examine the effect of ALDH2 deficiency on high-cholesterol diet-induced atherosclerotic plaque progression and plaque vulnerability in atherosclerosis-prone ApoE knockout (ApoE−/−) mice with a focus on foam cell formation in macrophages and senescence of vascular smooth muscle cells (VSMCs). Serum lipid profile, plaque progression, and plaque vulnerability were examined in ApoE−/− and ALDH2/ApoE double knockout (ALDH2−/−ApoE−/−) mice after high-cholesterol diet intake for 8 weeks. ALDH2 deficiency increased the serum levels of triglycerides while it decreased levels of total cholesterol and high-density lipoprotein cholesterol. Unexpectedly, ALDH2 deficiency reduced the plaque area by 58.9% and 37.5% in aorta and aortic sinus, respectively. Plaque instability was aggravated by ALDH2 deficiency along with the increased necrotic core size, decreased collagen content, thinner fibrous cap area, decreased VSMC content, and increased macrophage content. In atherosclerotic lesions, ALDH2 protein was located in both macrophages and VSMCs. Further results revealed downregulated ALDH2 expression in aorta of aged ApoE−/− mice compared with young mice. However, in vitro study suggested that ALDH2 expression was upregulated in bone marrow-derived macrophages (BMDMs) with an opposite effect in VSMCs following 80 μg/ml oxidized low-density lipoprotein (oxLDL) treatment. Interestingly, ALDH2 deficiency displayed little effect in oxLDL-induced foam cell formation from BMDMs, while ALDH2 knockdown by siRNA and ALDH2 overexpression by lentivirus infection promoted and retarded oxLDL-induced VSMC senescence, respectively. Mechanistically, ALDH2 mitigated oxLDL-induced overproduction of mitochondrial reactive oxygen species (mROS) and activation of downstream p53/p21/p16 pathway. Clearance of mROS by mitoTEMPO significantly reversed the promotive effect of ALDH2 knockdown on VSMC senescence. Taken together, our data revealed that ALDH2 deficiency suppressed atherosclerotic plaque area while facilitating plaque instability possibly through accelerating mROS-mediated VSMC senescence.This article is part of a Special Issue entitled: Genetic and epigenetic regulation of aging and longevity edited by Jun Ren & Megan Yingmei Zhang.

Defective autophagy in vascular smooth muscle cells enhances atherosclerotic plaque instability

Autophagy is considered as an evolutionarily conserved cellular catabolic process. Defective autophagy has been implicated in various human diseases, including cardiovascular diseases. Recently, we and others demonstrated that defective autophagy in vascular smooth muscle cells (SMCs) promotes the progression of atherosclerosis. In this study, we investigated the role of autophagy in SMCs on plaque instability in vivo. We generated mice with a defect atg7in which is an essential gene for autophagy, in SMCs by crossing Atg7f/f mice with transgelin (Tagln) Cre+/0 mice (Atg7cKO). Then, Atg7cKO and apolipoprotein E (apoe)-deficient (apoeKO) mice were crossed to generate Atg7cKO:apoeKO mice. To generate a mouse model of plaque instability, we conducted to form a tandem stenosis in the carotid artery of Atg7cKO:apoeKO mice and their controls (apoeKO mice) at the age of 10 weeks. At 5 weeks after surgery, the percentage of cross-sectional stenosis area in the operated common carotid artery of Atg7cKO:apoeKO mice was significantly higher than that in apoeKO mice. In addition, thrombus, which was not observed in apoeKO mice, was frequently found in Atg7cKO:apoeKO mice. Furthermore, the number of Berlin blue staining-positive areas, which indicated intraplaque hemorrhage, was significantly higher in Atg7cKO:apoeKO mice than in control apoeKO mice. Taken together, our data suggest that defective autophagy in SMCs enhances plaque instability and the risk of plaque rupture.

Up-regulation of COX-2 and mPGES-1 by 27-hydroxycholesterol and 4-hydroxynonenal: A crucial role in atherosclerotic plaque instability

Atherosclerosis is currently understood to be mainly the consequence of a complicated inflammatory process at the different stages of plaque development. Among the several inflammatory molecules involved, up-regulation of the functional cyclooxygenase 2/membrane-bound prostaglandin E synthase 1 (COX-2/mPGES-1) axis plays a key role in plaque development. Excessive production of oxidized lipids, following low-density lipoprotein (LDL) oxidation, is a characteristic feature of atherosclerosis. Among the oxidized lipids of LDLs, the oxysterol 27-hydroxycholesterol (27-OH) and the aldehyde 4-hydroxynonenal (HNE) substantially accumulate in the atherosclerotic plaque, contributing to its progression and instability through a variety of processes. This study shows that 27-OH and HNE promote up-regulation of both the inducible enzymes COX-2 and mPGES-1, leading to increased production of prostaglandin (PG) E2 and inducible nitric oxide synthase, and the subsequent release of nitric oxide in human promonocytic U937 cells. The study also examined the potential involvement of the functionally coupled COX-2/mPGES-1 in enhancing the production of certain pro-inflammatory cytokines and of matrix metalloproteinase 9 by U937 cells. This enhancement is presumably due to the induction of PGE2 synthesis, as a result of the up-regulation of the COX-2/mPGES-1, stimulated by the two oxidized lipids, 27-OH and HNE. Induction of PGE2 synthesis might thus be a mechanism of plaque instability and eventual rupture, contributing to matrix metalloproteinase production by activated macrophages.

The role of thrombin in central nervous system activity and stroke.

BackgroundThrombin is a key factor of hemostasis, mediating the conversion of fibrinogen into fibrin. Along with prothrombin, of which thrombin is the active derivative, it has been found locally expressed in the central nervous system. This article aims to describe the role of thrombin in the normal functioning of the central nervous system and stroke.MethodsIn this mini-review, the specialized databases Medscape, PubMed, and Web of Science, from the years 2003–2018, were used to find relevant documents by using MeSH terms: “thrombin” and “stroke”.ResultsProthrombin and thrombin influence neural development, protection and regeneration, thrombin being a relatively strong regulating factor of brain function. However, high levels of thrombin are detrimental to neuronal health, and cause atherosclerotic plaque development and instability - a leading cause of cerebral infarction. In stroke, thrombin promotes direct cellular toxicity, vascular disruption, oxidative stress and inflammatory response. There is a direct correlation between thrombin activity in the affected brain hemisphere and the infarction volume. Direct acting thrombin inhibitors, like dabigatran, significantly decrease the risk of ischemic stroke.ConclusionFurther studies on the correlation between thrombin levels, generation and activity and the risk and recurrence of ischemic cerebral stroke should give new insight on this association, resulting in an optimized practical therapeutic approach.

Vascular smooth muscle cells activate PI3K/Akt pathway to attenuate myocardial ischemia/reperfusion-induced apoptosis and autophagy by secreting bFGF

BackgroundVascular smooth muscle cells (VSMCs) has been reported to be implicated in atherosclerotic plaque instability and rupture. Recently, it has been demonstrated that VSMCs block the progression of cardiac remodeling and thus promoting cardiac function in a rat myocardial infarction model. However, the detailed molecular mechanism of how VSMCs contributes to recovery in myocardial ischemia/reperfusion remains not fully understood. MethodsWe have isolated, identified and cultured VSMCs from rats to co-culture with rat cardiomyocyte H9C2. To culture H9C2 cells under hypoxia, we utilized CoCl2-containing medium to culture for 8 h and then was replaced with normal media for additional 16 h. Cell viability was examined by MTT assay and apoptosis was determined by flow cytometry. Infarcted area of myocardial tissue was measured by TTC staining. ResultsVSMCs was shown to promote cell viability and inhibit apoptosis of H9C2 cells under hypoxia, which exhibited upregulated anti-apoptotic protein Bcl-2 and autophagy-related protein p62, whereas pro-apoptotic protein cleaved caspase-3 and the level of LC3II/LC3I were downregulated. Then, we confirmed VSMCs played the contributory role in cell viability of H9C2 under hypoxia by secreting bFGF, which exerted its function through PI3K/Akt pathway. Finally, in vivo, the results demonstrated that VSMCs transplantation contributed to recovery of myocardial ischemia. ConclusionWe determine that VSMCs promote recovery of infarcted cardiomyocyte through secretion of bFGF, which then activating PI3K/Akt pathway to inhibit apoptosis and autophagy. These findings provide more insights into the molecular mechanism underlying VSMCs contributing to recovery of myocardial I/R and facilitate developing therapeutical strategies for treating heart diseases.

Blockade of vascular endothelial growth factor receptor 2 inhibits intraplaque haemorrhage by normalization of plaque neovessels.

BackgroundPlaque angiogenesis is associated with atherosclerotic lesion growth, plaque instability and negative clinical outcome. Plaque angiogenesis is a natural occurring process to fulfil the increasing demand of oxygen and nourishment of the vessel wall. However, inadequate formed, immature plaque neovessels are leaky and cause intraplaque haemorrhage.ObjectiveBlockade of VEGFR2 normalizes the unbridled process of plaque neovessel formation and induces maturation of nascent vessels resulting in prevention of intraplaque haemorrhage and influx of inflammatory cells into the plaque and subsequently increases plaque stability.Methods and ResultsIn human carotid and vein graft atherosclerotic lesions, leaky plaque neovessels and intraplaque haemorrhage co‐localize with VEGF/VEGFR2 and angiopoietins. Using hypercholesterolaemic ApoE3*Leiden mice that received a donor caval vein interposition in the carotid artery, we demonstrate that atherosclerotic vein graft lesions at t28 are associated with hypoxia, Hif1α and Sdf1 up‐regulation. Local VEGF administration results in increased plaque angiogenesis. VEGFR2 blockade in this model results in a significant 44% decrease in intraplaque haemorrhage and 80% less extravasated erythrocytes compared to controls. VEGFR2 blockade in vivo results in a 32% of reduction in vein graft size and more stable lesions with significantly reduced macrophage content (30%), and increased collagen (54%) and smooth muscle cell content (123%). Significant decreased VEGF, angiopoietin‐2 and increased Connexin 40 expression levels demonstrate increased plaque neovessel maturation in the vein grafts. VEGFR2 blockade in an aortic ring assay showed increased pericyte coverage of the capillary sprouts.ConclusionInhibition of intraplaque haemorrhage by controlling neovessels maturation holds promise to improve plaque stability.

Protective effect of simvastatin on arterial plaque instability induced by p-cresyl sulfate.

To study the protective effect of simvastatin on arterial plaque instability induced by p-cresyl sulfate (PCS). Apolipoprotein E (ApoE)-/- mice were selected as objects of this study. All mice were randomly divided into three groups: 1) the control group, 2) the PCS group and 3) the PCS + simvastatin group. After successful modeling, the levels of plasma cholesterol, triglyceride, low-density lipoprotein, high-density lipoprotein, interleukin-1 (IL-1), interleukin-6 (IL-6) and tumor necrosis factor-β (TNF-β) were detected. The gross specimen of coronary artery was stained. Meanwhile, oil red O staining and Sirius red staining were performed for coronary arterial sections to observe the lipid and collagen components. The expression levels of smooth muscle cells and macrophages were observed by immunohistochemistry. In addition, the expression levels of matrix metalloproteinases (MMPs), tissue inhibitors of metalloproteinases (TIMPs) and monocyte chemoattractant protein-1 (MCP-1) in tissues were detected by Western blotting. Simvastatin could improve atherosclerotic plaque growth and atherosclerotic plaque instability induced by PCS. Moreover, simvastatin could also improve the changes of MMPs and TIMPs caused by PCS as well as the inflammatory status in mice. Simvastatin can improve the inflammatory status in mice, eventually improving the arterial plaque instability caused by PCS.

Differentiation of Type 1 and Type 2 Myocardial Infarctions Among HIV-Infected Patients Requires Adjudication Due to Overlap in Risk Factors.

The Universal Myocardial infarction (MI) definition divides MIs into different types. Type 1 MIs (T1MI) result spontaneously from atherosclerotic plaque instability. Type 2 MIs (T2MI) are due to secondary causes of myocardial oxygen demand/supply mismatch such as occurs with sepsis. T2MI are much more common among those with HIV than in the general population. T1MI and T2MI have different mechanisms, risk factors, and potential treatments suggesting that they should be distinguished to achieve a better scientific understanding of MIs in HIV. We sought to determine whether MI type could be accurately predicted by patient characteristics without adjudication in HIV-infected individuals. We developed a statistical model to predict T2MI versus T1MI using adjudicated events from six sites utilizing demographic characteristics, traditional cardiovascular, and HIV-related risk factors. Validation was assessed in a seventh site via mean calibration, and discrimination level was assessed by the area under the curve (AUC). Of 812 MIs, 388 were T2MI. HIV-related factors including hepatitis C infection were predictive of T2MI, whereas traditional cardiovascular risk factors including total cholesterol predicted T1MI. The score predicted 69 T2MI in the validation sample resulting in poor calibration, given that 90 T2MIs were observed. The development sample AUC was 0.75 versus 0.65 in the validation sample, suggesting relatively poor discrimination. The level of discrimination to predict MI type based on patient characteristics is insufficient for individual level prediction. Adjudication is required to distinguish MI types, which is necessary to advance understanding of this important outcome among HIV populations.

Oxidized lipids in atherosclerotic plaque instability

A large body of evidence suggests a mechanistic link between oxidized lipids and atherosclerosis. Oxysterols and 4-hydroxynonenal (HNE), the major products deriving from LDL oxidation, are consistently present in inflamed and atherosclerotic arteries and they play a key role in the development of atherosclerosis (1,2). Due to the fact that atherosclerosis is a leading cause of mortality in Western countries, it is of increasing importance to understand the various molecular mechanisms induced by oxysterols and HNE, as well as to identify new markers to distinguish between stable and unstable atherosclerotic plaques. Since chronic inflammation and matrix degradation might play a key role in plaque instability, we investigated the effect of oxysterols and HNE on various inflammatory molecules and MMP-9 expression in promonocytic U937 cells. In U937 cells, both oxysterols and HNE induced the expression of several cytokines and MMP-9 through TLR4 activation. These oxidized lipids also sustained inflammation by upregulating COX-2 and mPGES-1 levels, enzymes that cooperate to catalyze the conversion of arachidonic acid to PGE2. Inhibition of inflammatory molecule formation decrease MMP-9 release by macrophages, underlying the crucial role of inflammatory response in MMP-9 overexpression, a major marker of atherosclerotic plaque instability. Recently, it has been reported that proprotein convertase PCSK6, a new marker of plaque instability, is overexpressed in symptomatic carotid plaques. In connection with this, we are now investigating whether an oxysterol mixture and HNE can modulate the expression of PCSK6. Preliminary results indicate that both oxysterols and HNE upregulate PCSK6 in U937 cells. The downregulation of PCSK6 by siRNA significantly reduced MMP-9 activity induced by oxidized lipids, underlying a possible link between PCSK6 activity and MMP activation. Our results suggest that oxysterols and HNE contribute to atherosclerotic plaque instability by enhancing the inflammatory response and favouring matrix degradation through MMP-9 upregulation. Moreover, preliminary results indicate that PCSK6, upregulated by oxysterols or HNE, might play a key role in plaque instability by increasing MMP activity. These results might provide strong incentive for the development of new therapeutic strategies to counteract the risk of atherosclerotic plaque rupture and thrombosis, which cause acute coronary syndromes.

Tropoelastin: A novel marker for plaque progression and instability.

Elastolysis and ineffective elastogenesis favor the accumulation of tropoelastin, rather than cross-linked elastin, in atherosclerotic plaques. We developed gadolinium-labeled tropoelastin-specific magnetic resonance contrast agents (Gd-TESMAs) for tropoelastin imaging in animal models. Two peptides, VVGSPSAQDEASPLS and YPDHVQYTHY were selected to target tropoelastin. In vitro binding, relaxivity, and biodistribution experiments enabled characterization of the probes and selecting the best candidate for in vivo MRI. MRI was performed in atherosclerotic apolipoprotein E-deficient (ApoE-/-) mice and New Zealand white rabbits with stable and rupture-prone plaques using Gd-TESMA. Additionally, human carotid endarterectomy specimens were imaged ex vivo. The VVGSPSAQDEASPLS-based probe discriminated between tropoelastin and cross-linked elastin (64±7% vs 1±2%, P=0.001), had high in vitro relaxivity in solution (r1-free=11.7±0.6mM-1s-1, r1-bound to tropoelastin = 44±1mM-1s-1) and favorable pharmacokinetics. In vivo mice vascular enhancement (4wks=0.13±0.007mm2, 8wks=0.22±0.01mm2, 12wks=0.33±0.01mm2, P<0.001) and R1 relaxation rate (4wks=0.90±0.01 s-1, 8wks=1.40±0.03 s-1, 12wks=1.87±0.04s-1, P<0.001) increased with atherosclerosis progression after Gd-TESMA injection. Conversely, statin-treated (0.13±0.01mm2, R1 =1.37±0.03s-1) and control (0.10±0.005mm2, R1 =0.87±0.05s-1) mice showed less enhancement. Rupture-prone rabbit plaques had higher R1 relaxation rate compared with stale plaques (R1=2.26±0.1s-1vs R1=1.43±0.02s-1, P=0.001), after administration of Gd-TESMA that allowed detection of rupture-prone plaques with high sensitivity (84.4%) and specificity (92.3%). Increased vascular R1 relaxation rate was observed in carotid endarterectomy plaques after soaking (R1pre= 1.1±0.26 s-1 vs R1post= 3.0±0.1s-1, P=0.01). Ex vivo analyses confirmed the MRI findings and showed uptake of the contrast agent to be specific for tropoelastin. MRI of tropoelastin provides a novel biomarker for atherosclerotic plaque progression and instability.

FSI analysis in stenotic coronary artery model: progress of atherosclerosis and vulnerable hemorheology

Aim: Wall shear stress (WSS), as an mechanical force to vascular wall, is known to be a important risk factor for atherogenesis and atherosclrotic progression. And, mechanical response and properties of the arterial wall can be used to identify the biomechanical instability of atherosclerotic plaques and predict their vulnerability to rupture. The purpose of this study was to investigate the hemodynamic information of atherosclerotic plaque rupture with various conditions using fluid structure interaction (FSI).

Myeloperoxidase is a potential molecular imaging and therapeutic target for the identification and stabilization of high-risk atherosclerotic plaque.

As the inflammatory enzyme myeloperoxidase (MPO) is abundant in ruptured human atherosclerotic plaques, we aimed to investigate the role of MPO as a potential diagnostic and therapeutic target for high-risk plaque. We employed the tandem stenosis model of atherosclerotic plaque instability in apolipoprotein E gene knockout (Apoe-/-) mice. To test the role of MPO, we used Mpo-/-Apoe-/- mice and the 2-thioxanthine MPO inhibitor AZM198. In vivo MPO activity was assessed by liquid chromatography-tandem mass spectrometry detection of 2-chloroethidium generation from hydroethidine and by bis-5HT-DTPA-Gd (MPO-Gd) molecular magnetic resonance imaging (MRI), while plaque phenotype was verified histologically. Myeloperoxidase activity was two-fold greater in plaque with unstable compared with stable phenotype. Genetic deletion of MPO significantly increased fibrous cap thickness, and decreased plaque fibrin and haemosiderin content in plaque with unstable phenotype. AZM198 inhibited MPO activity and it also increased fibrous cap thickness and decreased fibrin and haemosiderin in plaque with unstable phenotype, without affecting lesion monocytes and red blood cell markers or circulating leukocytes and lipids. MPO-Gd MRI demonstrated sustained enhancement of plaque with unstable phenotype on T1-weighted imaging that was two-fold greater than stable plaque and was significantly attenuated by both AZM198 treatment and deletion of the Mpo gene. Our data implicate MPO in atherosclerotic plaque instability and suggest that non-invasive imaging and pharmacological inhibition of plaque MPO activity hold promise for clinical translation in the management of high-risk coronary artery disease.

The changes and clinical significance of plasma lipoprotein-associated phospholipase A2, C-reactive protein and cardiac troponin I in patients with acute coronary syndrome

Objective To investigate the relationship between lipoprotein associated phospholipase A2 (Lp-PLA2) and atherosclerotic plaque instability in patients with acute coronary syndrome (ACS), and to provide theoretical basis for diagnosis and treatment of ACS. Methods From September 2015 to February 2016, 80 patients with ACS in Shidao People's Hospital of Rongcheng were selected as the study group, including 38 cases in unstable angina group(UAP group), 24 cases in non ST segment elevation myocardial infarction group (NSTEMI group), 18 cases in ST segment elevation myocardial infarction group(STEMI group). Forty patients with stable angina pectoris(SAP group) and 40 healthy subjects(healthy group) were selected as control group.Each group was collected 8 hours fasting morning blood sample, the levels of Lp-PLA2, C reactive protein(CRP), troponin I, and low density lipoprotein were detected, in order to compare the differences among the groups and the correlation between Lp-PLA2 and ACS plaque instability was analyzed. Results The levels of Lp-PLA2, CRP, troponin I and low density lipoprotein in the ACS group were (312.63±11.14)ng/mL, (21.98±7.83)mg/L, (0.720±0.490)μg/L, (174.76±30.82)mg/dL, respectively, which were significantly higher than those of the healthy group [(141.14±12.30)ng/mL, (2.38±1.68)mg/L, (0.010±0.003)μg/L, (79.24±17.80)mg/Ml], and stable angina pectoris group[(176.42±12.44)ng/mL, (4.22±3.68)mg/L, (0.010±0.004)μg/L, (96.54±19.41)mg/mL]. There were statistically significant differences among all groups(F=3.07, 1.99, 2.43, 3.25, all P<0.01). The levels of CRP, Lp-PLA2 and cTnI in ACS patients with different types of the STEMI group, NSTEMI group, UAP group had statistically significant differences, which of the STEMI group were higher than those of the NSTEMI group, which of the NSTEMI group were higher than those of the UAP group(F=5.15, 3.47, 2.43, all P<0.05). Correlation analysis showed that the level of Lp-PLA2 was positively correlated with low density lipoprotein(r=0.625, P<0.01) and lipoprotein a(r=0.532, P<0.01). logistic regression analysis showed that Lp-PLA2 and CRP were significant independent risk factors of ACS, Lp-PLA2(OR=1.613, 95%CI: 1.292-1.992, P<0.01), CRP(OR=1.452, 95%CI: 1.210-1.782, P<0.01). Conclusion Lp-PLA2 is independent risk factor of ACS.Lp-PLA2 is involved in the inflammatory reaction of ACS, and is strongly associated with the stability of atherosclerotic plaque. Key words: Acute coronary syndrome; Lipoprotein-associated phospholiase A2; C-reactive protein; cardiac troponin I; Regression analysis

Change of Inflammatory Factors in Patients with Acute Coronary Syndrome.

Background:Acute coronary syndrome (ACS) is closely related to unstable plaques and secondary thrombosis. The inflammatory cells in plaques and their inflammatory products may be the cause for plaque instability and ruptures. The study aimed to disclose the changes of inflammatory factors including serum intracellular adhesion molecule-1 (ICAM-1), chitinase-3-like protein 1 (YKL-40), and lipoprotein-associated phospholipase A2 (Lp-PLA2) in patients with ACS and its clinical significance.Methods:A total of 120 patients with coronary heart disease (CHD) were categorized into 2 groups: 69 with ACS and 51 with stable angina pectoris (SAP); 20 patients with chest pain and normal angiography served as a control group. The 120 patients with CHD were categorized into single-vessel disease group, double-vessel disease group, and three-vessel disease group based on the number of coronary artery stenosis. The severity of coronary artery stenosis was quantified based on coronary angiography using Gensini score. They were further divided into mild CHD group with its Gensini score <26 (n = 36), moderate CHD group with its Gensini score being 26–54 (n = 48) and severe CHD group with its Gensini score >54 (n = 36). Serum levels of ICAM-1, YKL-40, and Lp-PLA2 of different groups were determined by enzyme-linked immunosorbent assay. Correlation between ICAM-1, YKL-40, Lp-PLA2, and Gensini score was analyzed.Results:The levels of serum inflammatory factors ICAM-1, YKL-40, and Lp-PLA2 were significantly higher in the ACS group than those in control group and SAP group (all P < 0.05); and compared with control group, no significant difference was observed in terms of the serum ICAM-1, YKL-40, and Lp-PLA2 levels in the SAP group (P > 0.05).The levels of serum ICAM-1, YKL-40, and Lp-PLA2 were not significantly different among control group, single-vessel disease group, double-vessel disease group, and three-vessel disease group (all P > 0.05). The levels of serum ICAM-1, YKL-40, and Lp-PLA2 were not significantly different among control group, mild CHD group (Gensini score <26), moderate CHD group (Gensini score 26–54), and severe CHD group (Gensini score >54) (all P > 0.05).Conclusions:The serum levels of ICAM-1, YKL-40, and Lp-PLA2 were correlated with different clinical types of CHD, but not well correlated the severity and extent of artery stenosis, suggesting that ICAM-1, YKL-40, and Lp-PLA2 might be involved in occurrence of instability of atherosclerotic plaque, and might reflect the severity of CHD mostly through reflecting the plaque stability.

Nuclear factor E2-related factor 2 deficiency impairs atherosclerotic lesion development but promotes features of plaque instability in hypercholesterolaemic mice.

Oxidative stress and inflammation play an important role in the progression of atherosclerosis. Transcription factor NF-E2-related factor 2 (Nrf2) has antioxidant and anti-inflammatory effects in the vessel wall, but paradoxically, global loss of Nrf2 in apoE deficient mice alleviates atherosclerosis. In this study, we investigated the effect of global Nrf2 deficiency on early and advanced atherogenesis in alternative models of atherosclerosis, LDL receptor deficient mice (LDLR-/-), and LDLR-/- mice expressing apoB-100 only (LDLR-/- ApoB100/100) having a humanized lipoprotein profile. LDLR-/- mice were fed a high-fat diet (HFD) for 6 or 12 weeks and LDLR-/-ApoB100/100 mice a regular chow diet for 6 or 12 months. Nrf2 deficiency significantly reduced early and more advanced atherosclerosis assessed by lesion size and coverage in the aorta in both models. Nrf2 deficiency in LDLR-/- mice reduced total plasma cholesterol after 6 weeks of HFD and triglycerides in LDLR-/-ApoB100/100 mice on a chow diet. Nrf2 deficiency aggravated aortic plaque maturation in aged LDLR-/-ApoB100/100 mice as it increased plaque calcification. Moreover, ∼36% of Nrf2-/-LDLR-/-ApoB100/100 females developed spontaneous myocardial infarction (MI) or sudden death at 5 to 12 months of age. Interestingly, Nrf2 deficiency increased plaque instability index, enhanced plaque inflammation and calcification, and reduced fibrous cap thickness in brachiocephalic arteries of LDLR-/-ApoB100/100 female mice at age of 12 months. Absence of Nrf2 reduced atherosclerotic lesion size in both atherosclerosis models, likely via systemic effects on lipid metabolism. However, Nrf2 deficiency in aged LDLR-/-ApoB100/100 mice led to an enhanced atherosclerotic plaque instability likely via increased plaque inflammation and oxidative stress, which possibly predisposed to MI and sudden death.

Anti-Atherogenic Effects of Vaspin on Human Aortic Smooth Muscle Cell/Macrophage Responses and Hyperlipidemic Mouse Plaque Phenotype.

Vaspin (visceral adipose tissue-derived serine protease inhibitor) was recently identified as a novel adipocytokine with insulin-sensitizing effects. Serum vaspin levels are reported either increased or decreased in patients with coronary artery disease. Our translational research was performed to evaluate the expression of vaspin in human coronary atherosclerotic lesions, and its effects on atherogenic responses in human macrophages and human aortic smooth muscle cells (HASMC), as well as aortic atherosclerotic lesion development in spontaneously hyperlipidemic Apoe−/− mice, an animal model of atherosclerosis. Vaspin was expressed at high levels in macrophages/vascular smooth muscle cells (VSMCs) within human coronary atheromatous plaques. Vaspin significantly suppressed inflammatory phenotypes with nuclear factor κB down-regulation in human macrophages. Vaspin significantly suppressed oxidized low-density lipoprotein-induced foam cell formation with CD36 and acyl-coenzyme A: cholesterol acyltransferase-1 down-regulation and ATP-binding cassette transporters A1 and G1, and scavenger receptor class B type 1 up-regulation in human macrophages. Vaspin significantly suppressed angiotensin II-induced migration and proliferation with ERK1/2 and JNK down-regulation, and increased collagen production with phosphoinositide 3-kinase and Akt up-regulation in HASMCs. Chronic infusion of vaspin into Apoe−/− mice significantly suppressed the development of aortic atherosclerotic lesions, with significant reductions of intraplaque inflammation and the macrophage/VSMC ratio, a marker of plaque instability. Our study indicates that vaspin prevents atherosclerotic plaque formation and instability, and may serve as a novel therapeutic target in atherosclerotic cardiovascular diseases.

Role of Ligands of Receptor for Advanced Glycation End Products (RAGE) in Peripheral Artery Disease

Atherosclerotic cardiovascular disease, including peripheral artery disease (PAD), is more common and severe in diabetic patients compared with nondiabetic individuals. Indeed, diabetes is associated with the increased risk of limb amputation and all-cause mortality in patients with symptomatic PAD. Proteins and lipids are nonenzymatically modified by sugars, resulting in the formation and accumulation of advanced glycation end products (AGEs), whose process is accelerated under diabetic conditions, especially patients with a long duration of diabetes. Accumulating evidence shows that nonenzymatic modification by sugars alters the structural integrity of collagens and lipoproteins in large vessels, thereby being involved in vascular stiffness and atherosclerotic plaque instability. Furthermore, engagement of receptor for AGEs (RAGE) with its ligands, such as AGEs, high mobility group box 1, and S100A proteins evokes inflammatory and thrombotic reactions, thus playing a central role in the development and progression of atherosclerotic cardiovascular disease. In this article, we review the pathophysiological role of RAGE ligands in PAD and discuss the clinical utility of measurement of plasma, serum, or tissue RAGE ligands for assessment of the severity and prognosis of PAD. This review suggests that RAGE ligands may be a novel biomarker and also a therapeutic target of PAD, especially in patients with diabetes.