Abstract 593: Hypoxia is Present in the Macrophage-rich Center of Human Carotid Atherosclerotic Plaques

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Judith C Sluimer ◽  
Job L van Wanroij ◽  
Matthijs Groeneweg ◽  
Bradly G Wouters ◽  
Mat J Daemen ◽  
...  

Intraplaque neovascularization is linked to plaque instability and thought to be stimulated by hypoxia. However, hypoxia has not been demonstrated yet in human atherosclerosis. The hypoxia marker pimonidazole was administrated intravenously 2 hours prior to carotid endarterectomy in 6 symptomatic patients to evaluate the presence of hypoxia. Subsequent immunohistochemistry of the operatively removed atherosclerotic plaques demonstrated the presence of hypoxia, especially in the macrophage-rich center of the lesions. Notably, two hypoxic gradients were observed: hypoxia was very strong in the center of the plaque, but almost absent close to the main artery lumen and in the media. hypoxia was most intense in segments with advanced atheroma and almost absent in segments containing only diffuse intimal thickening. Hypoxia strongly correlated with CD68 immunoreactivity (ρ= 0.7, p=0.000), neovascularization (ρ= 0.6, p=0.000) and the presence of a thrombus (ρ= 0.4, p=0.009). In addition, hypoxia co-localized with expression of HIF1α and VEGF . To exclude that pimonidazole immunoreactivity in the atherosclerotic plaque was the result of surgery-induced ischemia, arterial wall segments were collected at two time-points: directly after incision of the carotid artery and directly following excision of the plaque. Pimonidazole immunoreactivity in these two pieces was not different, suggesting that hypoxia and pimonidazole adducts were already present in the plaques before surgery . To show that pimonidazole reactivity was hypoxia-specific and independent of reactive oxygen species, human THP-1 macrophages were exposed to normoxia (20% O 2 ), hypoxia (0.2% O 2 ) and/or H 2 O 2 (100 μM) in the presence of pimonidazole. Indeed, flow cytometry only showed pimonidazole-positive cells after hypoxic exposure. This is the first study proving direct evidence of the existence of hypoxia in advanced human atherosclerotic lesions, most prominently in the macrophage-rich center. Also, hypoxia was associated with the expression of HIF1α, VEGF and intraplaque microvessels, suggesting its involvement in the regulation of human intraplaque neovascularization.

2021 ◽  
Author(s):  
Paula González-López ◽  
Carla Ares-Carral ◽  
Andrea R. López-Pastor ◽  
Jorge Infante-Menéndez ◽  
Tamara Gonzalez-Illanes ◽  
...  

Abstract 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.


2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
X Jiang ◽  
F Wang ◽  
J Wang ◽  
A Gistera ◽  
J Roy ◽  
...  

Abstract A trait of inflammation pathogenesis in human atherosclerosis: inflammasome driven interleukin-1 signalling in complex atherosclerotic plaques via hyperlipidemia trained innate immunity Objectives We aimed to investigate interleukin (IL)-1 generation and the regulatory role of inflammasome in human advanced atherosclerosis. Background IL-1β is key contributor to the inflammatory process associated with atherosclerosis and its complications. Recent studies suggested that IL-1β blockade reduces the burden of inflammation and recurrence of cardiovascular events. Yet, other cytokines in IL-1 family and the regulation of IL-1 generation in patients with atherosclerosis remains poorly understood. Methods and results A focused transcriptomic analysis in human atherosclerotic specimens discovered that human atherosclerotic plaques host a broad reservoir of inflammasome components, characterised by expression of canonical inflammasome gene NLRP6, NLRP12, NLRC4, NLRP3 and non-canonical inflammasome gene caspase 4 significantly elevated in the symptomatic plaques versus the asymptomatic plaques. Upregulation of NLRP3 inflammasome expression in plaque validated by immunohistochemistry staining suggested it as a distinctive characteristic of plaque vulnerability and complexity. Functional studies on atherosclerotic explants obtained from patients undergoing carotid endarterectomy revealed constitutive generation of IL-1β accompanied by secretion of comparable levels of IL-1α from the majority of the plaques, while IL-18 and IL-33 generation from some of the plaques. Stimulation of the plaques with inflammasome activators showed an inducible generation of both IL-1α and IL-1β, not IL-18 or IL-33, mediated by specific canonical and non-canonical inflammasome pathways. Analysis on the medication records of these patients indicated that plaques from patients with suboptimally controlled hyperlipidemia, imaging signs for plaque instability and inadequate statins therapy possessed higher recruitable production of IL-1β, suggesting the conventional atherogenic factor in regulation of inflammasome immunity and disease activity. Mechanistic studies on tissue and cells isolated from atheromatous plaques demonstrate that generation of mature IL-1β is via a mechanism controlled by NLRP3 and the effector caspase-1. Conclusions The study supports a profound canonical and non-canonical inflammasomes mediated plaque IL-1α/β generation, via a key mechanism by NLRP3 and caspase-1. The results provide biological insights into the clinical merit of high-intensity cholesterol lowering and anti-IL-1 signalling-directed therapies in high-risk patients with atherosclerosis. Acknowledgement/Funding KI-Mayo collaboration project, the Swedish Research Council, the Swedish Heart-Lung Foundation, European Union FP7 projects, the NIH


2019 ◽  
Vol 6 (3) ◽  
pp. 36-43
Author(s):  
D. E. Zaitsev ◽  
G. E. Trufanov

Background. Studying the possibilities of ultrasound diagnosis of atherosclerotic lesions of the carotid arteries to determine the treatment tactics of patients with various types of atherosclerotic plaques.Objective. Assessment of the possibilities of ultrasonic triplex research in identifying signs of instability of atherosclerotic plaques of the carotid arteries.Design and methods. The study included 360 patients aged from 28 to 95 years old who were admitted to the St. Petersburg State Budgetary Health Institution “Mariinskaya Hospital” with diagnoses of transient ischemic attack and acute cerebrovascular accident. All patients underwent an ultrasound visualization of the brachiocephalic arteries. Results. Most patients had atherosclerotic plaques of the carotid arteries with a stenosis of up to 75 % and had signs of instability with varying degrees of severity (according to triplex ultrasound). However, it was not possible to reliably assess the presence of hemorrhage in the plaque using a single imaging method.Conclusion. The data obtained indicate the complexity and ambiguity of the studied question. Further detailed examination of the signs of atherosclerotic plaque instability is required using various diagnostic imaging techniques.


2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Siqin Zhaorigetu ◽  
Chien-An A Hu ◽  
Warren Laskey ◽  
Brian Walton

Background: We recently demonstrated that apolipoprotein L6 (ApoL6) regulates apoptosis and autophagy in atherosclerotic lesions, implying that ApoL6 is an important factor that causes plaque instability and a potential therapeutic target for treating atherosclerosis. To further investigate the role of ApoL6 in atherogenesis in vivo , the expression of ApoL6 was knocked down by the liposome-siRNA strategy in the aorta tissue of ApoE -/- mouse. Methods: Liposomal siRNAs were prepared by using the thin-film hydration method and were labeled with quantum dots (QD). ApoE -/- mice were intravenously injected twice in 1 week with either liposomal control siRNA-QD or liposomal ApoL6 siRNA-QD. We harvested aortic tissue from mice and used immunofluorescence staining to analyze the expression of ApoL6 in atherosclerotic plaque. Results: Immunofluorescence analysis showed that expression of ApoL6 was elevated in the atherosclerotic plaque and partially co-localized with a macrophage marker CD68 in ApoE -/- mouse. The results suggest a link between ApoL6 and macrophages in the pathobiology of atherosclerotic lesions ( Fig. A and B ). Confocal microscopy images showed that liposomal ApoL6 siRNA significantly reduced ApoL6 expression (green punctures) in atherosclerotic plaques as compared with liposomal control siRNA (Fig. C) . Conclusion: We established a silencing model of ApoL6 in cardiovascular system of ApoE -/- mouse using liposome-mediated siRNA delivery system. The intravenous injection of liposomal ApoL6 siRNA silences ApoL6 expression in the aortas of ApoE -/- mice and may protect against the development of atherosclerosis.


2012 ◽  
Vol 302 (2) ◽  
pp. H451-H458 ◽  
Author(s):  
Decha Pinkaew ◽  
Nongporn Hutadilok-Towatana ◽  
Ba-Bie Teng ◽  
Wilawan Mahabusarakam ◽  
Ken Fujise

While macrophages take up modified LDL to form foam cells and multiply to develop fatty streaks, vascular smooth muscle cells (VSMC) migrate from the media to intima, secrete extracellular matrix, and increase the volume of atherosclerotic lesions. A medicinal plant Garcinia dulcis has been used in traditional Thai medicine for centuries to treat various chronic human diseases. Morelloflavone, a biflavonoid and an active ingredient of the plant, has been shown to inhibit VSMC migration through its inhibition of multiple migration-related kinases such as focal adhesion kinase, c-Src, ERK, and RhoA. However, the exact role of morelloflavone in atherosclerogenesis was unknown. We fed Ldlr−/−Apobec1−/− mice with either normal chow or chow containing 0.003% morelloflavone for 8 mo and assessed the extent of atherosclerosis by the en face and cross-sectional analyses. A cell composition analysis of atherosclerotic tissue was carried out using immunohistochemical staining. Oral morelloflavone therapy significantly reduced the atherosclerotic areas of the mouse aortas (a 26% reduction), without changing plasma lipid profiles or weights. Immunohistochemical analyses showed that morelloflavone reduced the number of VSMC in the atherosclerotic lesion while it did not change the density of macrophages in the lesion or the percentages of proliferating and apoptotic cells. Oral, low-dose, morelloflavone therapy retards atherosclerogenesis by limiting the migration of VSMC into the intima in the mouse model of human atherosclerosis. Upon further investigation, morelloflavone may be found to be a novel oral antiatherosclerotic agent and a viable addition to the conventional therapies such as statins in humans.


Stroke ◽  
2012 ◽  
Vol 43 (suppl_1) ◽  
Author(s):  
Xihai Zhao ◽  
Huilin Zhao ◽  
Feiyu Li ◽  
Jie Sun ◽  
Ye Cao ◽  
...  

Introduction Rupture of vulnerable atherosclerotic plaques in the intracranial and extracranial carotid arteries could trigger ischemic stroke. However, the incidence of high risk atherosclerotic lesions in these vascular beds is not well known. This study sought to investigate the incidence of high risk atherosclerotic lesions in intracranial and extracranial carotid arteries in stroke patients using magnetic resonance (MR) imaging. Methods Seventy-five patients (mean age 62.7 years, 56 males) with acute ischemic stroke underwent MR imaging for index carotid arteries, assigned as the same side as the brain lesions, with a Philips 3.0T MR scanner. Intracranial carotid MR angiography was performed using 3D TOF sequence with FOV of 23 × 23 cm 2 , matrix of 256 × 256, and a slice thickness of 1mm. The multi-contrast vessel wall images (3D TOF, T1W, T2W, and MP-RAGE) were acquired for extracranial carotid arteries with FOV of 14 × 14 cm 2 , matrix of 256 × 256, and slice thickness of 2 mm. The intracranial artery includes middle cerebral artery (MCA), anterior cerebral artery (ACA), and posterior cerebral artery (PCA). The extracranial carotid artery was divided into internal carotid artery (ICA), bulb, and common carotid artery (CCA). Luminal stenosis for each intracranial and extracranial carotid segment was measured and graded (normal or mild = 0-29%, moderate =30-69%, severe=70-99%). Normalized wall index (NWI = wall area/total vessel area × 100%), and presence/absence of calcification, lipid-rich necrotic core (LRNC), and intraplaque hemorrhage (IPH) and/or fibrous cap rupture in each extracranial carotid segment were determined. Results MCAs developed more severe stenotic lesions (24.6%), followed by extracranial carotids (16.5%), PCAs (5.4%), and ACAs (4.1%) in stroke patients ( Figure 1 A). For extracranial carotid arteries, ICAs showed the largest plaque burden as measured by NWI (44.3%±13.1%), followed by bulbs (39.4%±13%), and CCAs (37%±6.8%). Compared to CCAs, ICAs and bulb regions had more LRNCs (38.4% and 49.3% for ICA and bulb respectively) and IPH and/or rupture (11% and 9.6% for ICA and bulb respectively) ( Figure 1 B). Conclusions In patients with acute ischemic stroke, high risk atherosclerotic plaques can be found in both intracranial and extracranial carotid arteries, particularly in the MCA, ICA and bulb regions. Compared to extracranial carotid arteries, intracranial arteries develop more high risk lesions. The findings of this study suggest the necessity for early screening to detect high risk atherosclerotic lesions in these carotid vascular beds prior to cerebravascular events.


2009 ◽  
Vol 37 (4) ◽  
pp. 1029-1037 ◽  
Author(s):  
Z Qiao ◽  
J Ren ◽  
H Chen

Lipoprotein-associated phospholipase A2 (Lp-PLA2) contributes to atherosclerotic plaque instability and subsequent sudden coronary death. Statins are associated with decreased stroke risk and may improve stability of atherosclerotic plaques. The present study investigated the effect of simvastatin on expression of Lp-PLA2 levels in atherosclerotic plaques and on Lp-PLA2 activity in atherosclerotic aortas. Rabbits were a fed chow (control group) or a high-cholesterol diet (atherosclerosis group) for 12 weeks. An additional group on the high-cholesterol diet received simvastatin (5 mg/kg per day) for the last 4 weeks (simvastatin group). Lp-PLA2 activity in plasma and atherosclerotic aortas was significantly higher in the atherosclerosis group than in the control group and, consistent with this, abundant Lp-PLA2 protein was detected in plaques in the atherosclerosis group. Simvastatin significantly reduced Lp-PLA2 activity in plasma and aorta tissue, and reduced Lp-PLA2 protein level in atherosclerotic plaques. Whereas there was no significant difference in total atherosclerotic lesion area between simvastatin and atherosclerosis groups, simvastatin significantly reduced macrophage content, lipid retention and the intima/media ratio but increased the content of smooth muscle cells in atherosclerotic lesions. Thus, statin treatment markedly reduced Lp-PLA2 in both plasma and atherosclerotic plaques. This was associated with attenuation of the local inflammatory response and improved plaque stability.


2021 ◽  
Vol 7 ◽  
Author(s):  
Magnus Ziegler ◽  
Jesper Alfraeus ◽  
Elin Good ◽  
Jan Engvall ◽  
Ebo de Muinck ◽  
...  

Background: Atherosclerosis manifests as a focal disease, often affecting areas with complex hemodynamics such as the carotid bifurcation. The magnitude and regularity of the hemodynamic shear stresses acting on the vessel wall are thought to generate risk patterns unique to each patient and play a role in the pathogenesis of atherosclerosis. The involvement of different expressions of shear stress in the pathogenesis of carotid atherosclerosis highlights the need to characterize and compare the differential impact of the various expressions of shear stress in the atherosclerotic carotid bifurcation. Therefore, the aim of this study is to characterize and compare hemodynamic wall shear stresses (WSS) in the carotid arteries of subjects with asymptomatic atherosclerotic plaques. Shear stresses were also compared against vessel diameter and bifurcation angle to examine the relationships with the geometry of the carotid bifurcation.Methods: 4D Flow MRI and contrast-enhanced MRA data were acquired for 245 subjects with atherosclerotic plaques of at least 2.7 mm in conjunction with the Swedish CArdioPulmonary bioImage Study (SCAPIS). Following automatic segmentation and geometric analysis, time-resolved WSS and near-wall turbulent kinetic energy (nwTKE) were derived from the 4D Flow data. Whole-cycle parameters including time-averaged WSS and nwTKE, and the oscillatory shear index (OSI) were calculated. Pairwise Spearman rank-correlation analyses were used to investigate relationships among the hemodynamic as well as geometric parameters.Results: One hundred and seventy nine subjects were successfully segmented using automated tools and subsequently geometric and hemodynamic analyses were performed. Temporally resolved WSS and nwTKE were strongly correlated, ρ = 0.64. Cycle-averaged WSS and nwTKE were moderately correlated, ρ = 0.57. Cycle-average nwTKE was weakly correlated to OSI (ρ = −0.273), revealing that nwTKE provides information about disturbed flow on the vessel wall that OSI does not. In this cohort, there was large inter-individual variation for both WSS and nwTKE. Both WSS and nwTKE varied most within the external carotid artery. WSS, nwTKE, and OSI were weakly correlated to vessel diameter and bifurcation angle.Conclusion: The turbulent and mean component of WSS were examined together in vivo for the first time, and a strong correlation was found between them. nwTKE presents the opportunity to quantify turbulent wall stresses in vivo and gain insight into the effects of disturbed flow on the vessel wall. Neither vessel diameter nor bifurcation angle were found to be strongly correlated to the turbulent or mean component of WSS in this cohort.


2016 ◽  
Vol 2 (7) ◽  
pp. e1600224 ◽  
Author(s):  
Denuja Karunakaran ◽  
Michele Geoffrion ◽  
Lihui Wei ◽  
Wei Gan ◽  
Laura Richards ◽  
...  

Atherosclerosis results from maladaptive inflammation driven primarily by macrophages, whose recruitment and proliferation drive plaque progression. In advanced plaques, macrophage death contributes centrally to the formation of plaque necrosis, which underlies the instability that promotes plaque rupture and myocardial infarction. Hence, targeting macrophage cell death pathways may offer promise for the stabilization of vulnerable plaques. Necroptosis is a recently discovered pathway of programmed cell necrosis regulated by RIP3 and MLKL kinases that, in contrast to apoptosis, induces a proinflammatory state. We show herein that necroptotic cell death is activated in human advanced atherosclerotic plaques and can be targeted in experimental atherosclerosis for both therapeutic and diagnostic interventions. In humans with unstable carotid atherosclerosis, expression of RIP3 and MLKL is increased, and MLKL phosphorylation, a key step in the commitment to necroptosis, is detected in advanced atheromas. Investigation of the molecular mechanisms underlying necroptosis showed that atherogenic forms of low-density lipoprotein increase RIP3 and MLKL transcription and phosphorylation—two critical steps in the execution of necroptosis. Using a radiotracer developed with the necroptosis inhibitor necrostatin-1 (Nec-1), we show that 123I-Nec-1 localizes specifically to atherosclerotic plaques in Apoe−/− mice, and its uptake is tightly correlated to lesion areas by ex vivo nuclear imaging. Furthermore, treatment of Apoe−/− mice with established atherosclerosis with Nec-1 reduced lesion size and markers of plaque instability, including necrotic core formation. Collectively, our findings offer molecular insight into the mechanisms of macrophage cell death that drive necrotic core formation in atherosclerosis and suggest that this pathway can be used as both a diagnostic and therapeutic tool for the treatment of unstable atherosclerosis.


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