Hemodynamic Differences Between Basilar Artery Fenestration and Normal Vertebrobasilar Artery: A Pilot Study

Background: Basilar artery fenestration has been proposed as a contributor to ischemic stroke, as unique flow patterns induced by fenestration may be related to thrombus formation or insufficiency. This study aimed to evaluate the hemodynamics of basilar artery fenestration (BAF) using computational fluid dynamics (CFD).Methods: Patients with BAF and normal vertebrobasilar system were recruited and separately evaluated using CFD. Specific geometric vascular models were reconstructed based on 3D-rotational angiography (3D-RA). Patients were divided into the BAF group and control group (i.e., patients with the normal vertebrobasilar system). Hemodynamic and geometric variables were calculated and compared between groups using Student's t-test or Wilcoxon rank-sum test.Results: Overall, 24 patients were included, with 12 patients each in the BAF group and the control group. The BAF group had a significantly smaller basilar artery diameter than the control group (3.1 ± 0.51 vs. 3.76 ± 0.4, p = 0.002). Compared to the control group, the BAF group had higher values of maxOSI (median, 0.3 vs. 0.09, p = 0.028), TAWSSG (median, 983.42 vs. 565.39, p = 0.038) in the flow confluence, higher SAR-TAWSSG in bifurcation (median, 70.22 vs. 27.65, p = 0.002) and higher SAR-TAWSSG in basilar artery (median, 48.75 vs. 16.17, p < 0.001) of the vertebrobasilar artery.Conclusions: This pilot study suggested that hemodynamic differences between BAF and normal vertebrobasilar artery across multiple shear flow parameters. The disturbed flow in the BAF may increase the risk of thrombus formation, plaque instability, and subsequent ischemic cerebrovascular events. These should be confirmed by future studies.

Immune Mechanisms of Plaque Instability

Inflammation crucially drives atherosclerosis from disease initiation to the emergence of clinical complications. Targeting pivotal inflammatory pathways without compromising the host defense could compliment therapy with lipid-lowering agents, anti-hypertensive treatment, and lifestyle interventions to address the substantial residual cardiovascular risk that remains beyond classical risk factor control. Detailed understanding of the intricate immune mechanisms that propel plaque instability and disruption is indispensable for the development of novel therapeutic concepts. In this review, we provide an overview on the role of key immune cells in plaque inception and progression, and discuss recently identified maladaptive immune phenomena that contribute to plaque destabilization, including epigenetically programmed trained immunity in myeloid cells, pathogenic conversion of autoreactive regulatory T-cells and expansion of altered leukocytes due to clonal hematopoiesis. From a more global perspective, the article discusses how systemic crises such as acute mental stress or infection abruptly raise plaque vulnerability and summarizes recent advances in understanding the increased cardiovascular risk associated with COVID-19 disease. Stepping outside the box, we highlight the role of gut dysbiosis in atherosclerosis progression and plaque vulnerability. The emerging differential role of the immune system in plaque rupture and plaque erosion as well as the limitations of animal models in studying plaque disruption are reviewed.

Analysis of Predictive Model of Coronary Vulnerable Plaque under Hemodynamic Numerical Simulation

Objective. Vulnerable plaque is considered to be the cause of most clinical coronary arteries, and linear cytokines are an important factor causing plaque instability. Early prediction of vulnerable plaque is of great significance in the treatment of cardiovascular diseases. Methods. Computational fluid dynamics (CFD) was used to simulate the hemodynamics around plaques, and the serum biochemical markers in 224 patients with low-risk acute coronary syndrome (ACS) were analyzed. Vulnerable plaques were predicted according to the distribution of biochemical markers in serum. Results. CFD can accurately capture the hemodynamic characteristics around the plaque. The patient’s age, history of hyperlipidemia, apolipoprotein B (apoB), adiponectin (ADP), and sE-Selection were risk factors for vulnerable plaque. Area under curve (AUC) values corresponding to the five biochemical markers were 0.601, 0.523, 0.562, 0.519, 0.539, and the AUC value after the combination of the five indicators was 0.826. Conclusion. The combination of multiple biochemical markers to predict vulnerable plaque was of high diagnostic value, and this method was convenient and noninvasive, which was worthy of clinical promotion.

Sodium‐Glucose Co‐Transporter 2 (SGLT2) Inhibitor Dapagliflozin Stabilizes Diabetes‐Induced Atherosclerotic Plaque Instability

Background Diabetes is known to accelerate atherosclerosis and increase plaque instability. However, there has been a lack of suitable animal models to study the effect of diabetes on plaque instability. We hypothesized that the tandem stenosis mouse model, which reflects plaque instability/rupture as seen in patients, can be applied to study the effects of diabetes and respective therapeutics on plaque instability/rupture. Methods and Results ApoE −/− mice at 7 weeks of age were rendered diabetic with streptozotocin and 5 weeks later were surgically subjected to tandem stenosis in the right carotid artery and fed with a high‐fat diet for 7 weeks. As a promising new antidiabetic drug class, a sodium glucose co‐transporter 2 inhibitor was tested in this new model. Diabetic mice showed an increase in the size of unstable atherosclerotic plaques and in the plaque instability markers MCP‐1, CD68, and necrotic core size. Mice treated with dapagliflozin demonstrated attenuated glucose and triglyceride levels. Importantly, these mice demonstrated plaque stabilization with enhanced collagen accumulation, increased fibrosis, increased cap‐to‐lesion height ratios, and significant upregulation of the vasculoprotective NADPH oxidase 4 expression. Conclusions The tandem stenosis mouse model in combination with the application of streptozotocin represents a highly suitable and unique mouse model for studying plaque destabilization under diabetic conditions. Furthermore, for the first time, we provide evidence of plaque‐stabilizing effects of sodium‐glucose co‐transporter 2 inhibitor. Our data also suggest that this newly developed mouse model is an attractive preclinical tool for testing antidiabetic drugs for the highly sought‐after potential to stabilize atherosclerotic plaques.

Association Between 18-FDG Positron Emission Tomography and MRI Biomarkers of Plaque Vulnerability in Patients With Symptomatic Carotid Stenosis

Purpose: Pathologic studies suggest that unstable plaque morphology and inflammation are associated with cerebrovascular events. 18F-fluorodeoxyglucose positron emission tomography (18FDG-PET) is a validated technique for non-invasive imaging of inflammation-related plaque metabolism, and MRI can identify morphologic features of plaque instability. The aim of this study was to investigate the association of selected imaging characteristics of plaque vulnerability measured with MRI and PET in patients with symptomatic carotid stenosis.Methods: Patients from the BIOVASC study were selected based on the following inclusion criteria: (1) age ≥ 50 years; (2) recent (<30 days) ischaemic stroke (modified Rankin scale ≤3) or motor/speech/vision TIA; (3) ipsilateral internal carotid artery stenosis (≥5 0% lumen-narrowing); (4) carotid PET/CTA and MRI completed. Semi-automated plaque analysis of MRI images was performed to quantify morphologic features of plaque instability. PET images were co-registered with CTA and inflammation-related metabolism expressed as maximum standardised uptake value (SUVmax).Results: Twenty-five patients met inclusion criteria (72% men, mean age 65 years). MRI-measured plaque volume was greater in men (1,708–1,286 mm3, p = 0.03), patients who qualified with stroke (1,856–1,440 mm3, p = 0.05), and non-statin users (1,325–1,797 mm3, p = 0.03). SUVmax was associated with MRI-measured plaque lipid-rich necrotic core (LRNC) in the corresponding axial slice (rs = 0.64, p < 0.001) and was inversely associated with whole-plaque fibrous cap thickness (rs = −0.4, p = 0.02) and calcium volume (rs = −0.4, p = 0.03).Conclusion: This study demonstrated novel correlations of non-invasive imaging biomarkers of inflammation-related plaque metabolism with morphological MRI markers of plaque instability. If replicated, our findings may support the application of combined MRI and PET to detect vulnerable plaque in future clinical practise and randomised trials.

Implication of miR-155-5p and miR-143-3p in the Vascular Insulin Resistance and Instability of Human and Experimental Atherosclerotic Plaque

Background: Cardiovascular diseases (CVDs) are the main cause of death in first world countries, being atherosclerosis, a recurring process underlying their apparition. MicroRNAs (miRNAs) are small non-coding RNAs that modulate the expression of their target proteins. Therefore, they have emerged as key players in diseases like cancer, diabetes, or CVDs.Methods: Apolipoprotein E-deficient (ApoE-/-) mice fed a standard type diet (STD) or high fat diet (HFD) for 8 and 18 weeks was compared to wild type (WT) STD-fed groups for the same time. 18 miRNAs were selected (from pubmed and GEO database) for their possible role in promoting atherosclerosis and were analysed by RT-qPCR in the aorta from the experimental model. Afterwards, the altered miRNAs in the aorta from 18 weeks-ApoE-/- mice were studied in human healthy aortic samples, human early aortic atherosclerotic plaques, and human advanced carotid atherosclerotic plaques. Results: From the 18 miRNAs analyzed, miR-155-5p was overexpressed and miR-143-3p was downregulated in mouse and human atherosclerotic lesions. In addition, a significant decrease of protein kinase B (AKT), target of miR-155-5p, and an increase of insulin-like growth factor type II receptor (IGF-IIR), target of miR-143-3p, were noted in aortic roots from ApoE-/- mice and in carotid plaques from ACA patients. Finally, both miRNAs were studied on vascular endothelial and smooth muscle cell lines. The overexpression of miR-155-5p reduced AKT levels and its phosphorylation in vascular smooth muscle cells. MiR-143-3p overexpression decreased IGF-IIR reducing apoptosis in vascular cells. Conclusions: Our results suggest that miR-155-5p and miR-143-3p may be implicated in insulin resistance and plaque instability by the modulation of their targets AKT and IGF-IIR, contributing to the progression of experimental and human atherosclerosis.Trial Registration: authorization numbers PFS09-007 and PI1442016.

695 Upregulated monocyte expression of PLIN2 is associated with plaque instability in coronary artery disease

Aims Perilipin 2 (PLIN2), a protein associated with intracellular lipid droplets (LDs), is involved in lipid metabolism of macrophages resident in atherosclerotic plaques and its up-regulation leads to LDs accumulation. LDs enlargement results in the macrophage transformation into foam cells, a key step for the onset of atherosclerosis. In the present study, we investigated the role of PLIN2 and its regulation mechanisms in atherosclerosis and plaque instability in patients with a diagnosis of ST-elevation myocardial infarction (STEMI) and stable chronic angina (SA). Methods and results We enrolled 120 patients with a diagnosis of STEMI and 42 SA patients with symptoms of stable effort angina lasting more than 12 months. Peripheral blood mononuclear cells (PBMCs) were isolated from EDTA whole blood samples through standard gradient centrifugation over Ficoll-Hypaque. Monocytes were purified through indirect magnetic labelling of PBMCs. PLIN2 mRNA expression was investigated by Real Time-PCR and PLIN2 protein level was analysed in CD14+ monocytes by flow cytometry. Proteasome activity was assayed using AMC-tagged peptide substrate (Succ-LLVY-AMC), which releases free highly fluorescent AMC (Ex/Em 350/440 nm) in the presence of proteolytic activity. In CD14+ monocyte, PLIN2 protein expression was significantly increased in STEMI as compared to SA patients (P < 0.001), while PLIN2 mRNA level was not different in the two groups (P = n.s.). Despite proteasome activity was higher in STEMI as compared to SA patients (P < 0.001), significant inverse correlations were evident between PLIN2 levels and proteasome activity in the two groups (P = 0.05). Conclusions CD14+ monocyte PLIN2 protein expression was higher in STEMI as compared to SA patients suggesting an involvement in plaque instability. Despite proteasome activity was higher in STEMI patients, probably due to the elevated inflammatory burden, PLIN2 could escape proteasome degradation in a more efficient manner in STEMI as compared to SA patients.

Natural Killer T Cells Are Involved in Atherosclerotic Plaque Instability in Apolipoprotein-E Knockout Mice

The infiltration and activation of macrophages as well as lymphocytes within atherosclerotic lesion contribute to the pathogenesis of plaque rupture. We have demonstrated that invariant natural killer T (iNKT) cells, a unique subset of T lymphocytes that recognize glycolipid antigens, play a crucial role in atherogenesis. However, it remained unclear whether iNKT cells are also involved in plaque instability. Apolipoprotein E (apoE) knockout mice were fed a standard diet (SD) or a high-fat diet (HFD) for 8 weeks. Moreover, the SD- and the HFD-fed mice were divided into two groups according to the intraperitoneal injection of α-galactosylceramide (αGC) that specifically activates iNKT cells or phosphate-buffered saline alone (PBS). ApoE/Jα18 double knockout mice, which lack iNKT cells, were also fed an SD or HFD. Plaque instability was assessed at the brachiocephalic artery by the histological analysis. In the HFD group, αGC significantly enhanced iNKT cell infiltration and exacerbated atherosclerotic plaque instability, whereas the depletion of iNKT cells attenuated plaque instability compared to PBS-treated mice. Real-time PCR analyses in the aortic tissues showed that αGC administration significantly increased expressional levels of inflammatory genes such as IFN-γ and MMP-2, while the depletion of iNKT cells attenuated these expression levels compared to those in the PBS-treated mice. Our findings suggested that iNKT cells are involved in the exacerbation of plaque instability via the activation of inflammatory cells and upregulation of MMP-2 in the vascular tissues.

Non-lipid-rich low attenuation plaque with intraplaque haemorrhage assessed by multimodality imaging: a case report

Background The lipid-rich necrotic core is a major pathological hallmark of acute coronary syndrome. Low attenuation plaque (LAP) on coronary computed tomography angiography (CCTA), defined as plaque CT attenuation of <30 Hounsfield units, is commonly believed to correspond to the lipid component. This report presents a non-lipid-rich LAP with intraplaque haemorrhage of the left main coronary artery (LM), as assessed by CCTA, near-infrared spectroscopy (NIRS), and non-contrast magnetic resonance imaging (MRI) using coronary atherosclerosis T1-weighted characterisation with integrated anatomical reference technique, recently developed by our group. Case Summary A 75-year-old woman presented with chest discomfort on exertion. CCTA revealed severe stenosis of the mid-left circumflex coronary artery and minimal stenosis with a large eccentric LM plaque. The LM lesion had an LAP, with a minimum plaque attenuation of 25 Hounsfield units. On non-contrast T1-weighted MRI, a high-intensity plaque with a plaque-to-myocardium signal intensity ratio of 3.02 was observed within the vessel wall, indicating intraplaque haemorrhage. NIRS categorised the lesion as non-lipid-rich, with a maximum lipid core burden index in 4 mm of 169. Discussion Intraplaque haemorrhage is a key feature of plaque instability, which is different from the lipid-rich necrotic core. Non-contrast T1-weighted MRI is ideal for detecting intraplaque haemorrhage with short T1 values. The imaging findings suggest that LAP on CCTA may represent not only lipid-rich plaques but also intraplaque haemorrhage. MRI provides a unique insight into plaque vulnerability from a different perspective than lipid assessment. Multimodality imaging, including MRI, facilitates the understanding complicated plaque morphologies.

High Sensitivity C-Reactive Protein Increases the Risk of Carotid Plaque Instability in Male Dyslipidemic Patients

Background: The aim of this study was to evaluate how the high sensitivity C-reactive protein (hs-CRP) values influence the risk of carotid plaque instability in association with other cardiovascular risk factors. Methods: One hundred and fifty-six carotid plaques from both symptomatic and asymptomatic patients requiring surgical carotid endarterectomy were retrospectively collected. According to the modified American Heart Association, atherosclerosis plaques have been histologically distinguished into unstable and stable. The following anamnestic and hematochemical data were also considered: age, gender, hypertension, diabetes mellitus, smoking habit, therapy, low-density lipoprotein (LDL)-C, kidney failure and hs-CRP. Results: The results of our study clearly show that high levels of hs-CRP significantly increase the carotid plaque instability in dyslipidemic patients. Specifically, a 67% increase of the risk of carotid plaque instability was observed in patients with high LDL-C. Therefore, the highest risk was observed in male dyslipidemic patients 2333 (95% CI 0.73–7.48) and in aged female patients 2713 (95% CI 0.14–53.27). Discussion: These data strongly suggest a biological relationship between the hs-CRP values and the alteration of lipidic metabolism mostly in male patients affected by carotid atherosclerosis. The measurement of hs-CRP might be useful as a potential screening tool in the prevention of atheroscletotic disease.