Impaired high-density lipoprotein anti-oxidant capacity in human abdominal aortic aneurysm

Inhibition of VSMC Ferroptosis Mitigates Pathological Vascular Remodeling: A Novel Therapeutic Strategy for Abdominal Aortic Aneurysm

Ferroptosis plays a key role in abdominal aortic aneurysm (AAA) development. This study explores whether and how ferroptosis regulates AAA progression. Ferroptosis was confirmed in human AAA tissue. In vitro experiments with primary mouse vascular smooth muscle cells (VSMCs) and abdominal aortic rings revealed that angiotensin II (Ang II) triggered ferroptosis in VSMCs. Ferrostatin-1 (Fer-1), a potent ferroptosis inhibitor, effectively suppressed this effect. Additionally, the ferroptosis inducer erastin and Ang II can both promoted pathological remodeling of abdominal aortic rings, but Fer-1 significantly suppressed these effects. In AAA mouse model, Fer-1 treatment reduced AAA formation. Mechanistically, RNA-sequencing analysis revealed that Fer-1 regulates VSMC contractile function, suppresses inflammation, and mitigates extracellular matrix remodeling. These findings highlight the critical role of VSMC ferroptosis in AAA pathogenesis and demonstrate that ferroptosis inhibition effectively reduces pathological vascular remodeling, making it a promising therapeutic strategy for preventing AAA.

Iron Overload and Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a chronic vascular degenerative disease characterized by progressive segmental dilation of the abdominal aorta. The rupture of an AAA represents a leading cause of death in cardiovascular diseases. Despite numerous experimental and clinical studies examining potential drug targets and therapies, currently there are no pharmaceutical treatment to prevent AAA growth and rupture. Iron is an essential element in almost all living organisms and has important biological functions. Epidemiological studies have indicated that both iron deficiency and overload are associated with adverse clinical outcomes, particularly an increased risk of cardiovascular events. Recent evidence indicates that iron overload is involved in the pathogenesis of abdominal aortic aneurysms. In this review, we provide an overview of the role of iron overload in AAA progression and explore its potential pathological mechanisms. Although the exact molecular mechanisms of iron overload in the development of AAA remain to be elucidated, the inhibition of iron deposition may offer a promising strategy for preventing these aneurysms.

Prevalence of risk factors associated with rupture of abdominal aortic aneurysm (AAA): a single center retrospective study

BACKGROUND

Abdominal aortic aneurysm (AAA) is a severe cardiovascular disease. The mortality rate for an AAA rupture is very high. Understanding the risk factors for AAA rupture would help AAA management, but little is known about these risk factors in the Chinese population.

METHODS

This retrospective study included patients that were diagnosed with AAA during the last 5 years in a large national hospital in southern China. AAA patients were divided into a rupture and non-rupture group. Clinical data were extracted from the hospital medical record system. Clinical features were compared between the rupture and non-rupture groups. The associations between potential risk factors and rupture risk were evaluated using a multivariate logistic regression analysis.

RESULTS

A total of 337 AAA patients were included for analysis in the present study. AAA diameter was significantly larger, and high-sensitivity C-reactive protein (hs-CRP) and serum creatinine levels were both significantly higher in AAA rupture patients. High-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) levels were significantly lower in AAA rupture patients. After adjustment, the multivariate logistic analysis found that AAA diameter and hs-CRP were independently positively associated with AAA rupture, and HDL-C level was adversely associated with AAA rupture.

CONCLUSIONS

Our data suggests that larger AAA diameter and higher hs-CRP level are associated with a higher risk of AAA rupture, and higher HDL-C level is associated with a lower risk of AAA rupture. The results of this study may be helpful for the management of AAA patients in southern China.

SARS-CoV-2 induced HDL dysfunction may affect the host's response to and recovery from COVID-19

INTRODUCTION

Covid-19 is linked with the development of cardio-metabolic disorders, including dyslipidemia, dysregulation of high-density lipoprotein (HDL), and low-density lipoprotein (LDL). Furthermore, SARS-Co-2 infection is associated with noteworthy changes in lipid profile, which is suggested as a possible biomarker to support the diagnosis and management of Covid-19.

METHODS

This paper adopts the literature review method to obtain information about how Covid-19 affects high-risk group patients and may cause severe and critical effects due to the development of acute lung injury and acute respiratory distress syndrome. A narrative and comprehensive review is presented.

RESULTS

Reducing HDL in Covid-19 is connected to the disease severity and poor clinical outcomes, suggesting that high HDL serum levels could benefit Covid-19. SARS-CoV-2 binds HDL, and this complex is attached to the co-localized receptors, facilitating viral entry. Therefore, SARS-CoV-2 infection may induce the development of dysfunctional HDL through different mechanisms, including induction of inflammatory and oxidative stress with activation of inflammatory signaling pathways. In turn, the induction of dysfunctional HDL induces the activation of inflammatory signaling pathways and oxidative stress, increasing Covid-19 severity.

CONCLUSIONS

Covid-19 is linked with the development of cardio-metabolic disorders, including dyslipidemia in general and dysregulation of high-density lipoprotein and low-density lipoprotein. Therefore, the present study aimed to overview the causal relationship between dysfunctional high-density lipoprotein and Covid-19.

Identification of core cuprotosis-correlated biomarkers in abdominal aortic aneurysm immune microenvironment based on bioinformatics

Background

The occurrence of abdominal aortic aneurysms (AAAs) is related to the disorder of immune microenvironment. Cuprotosis was reported to influence the immune microenvironment. The objective of this study is to identify cuprotosis-related genes involved in the pathogenesis and progression of AAA.

Methods

Differentially expressed lncRNAs (DElncRNAs) and mRNAs (DEmRNAs) in mouse were identified following AAA through high-throughput RNA sequencing. The enrichment analyses of pathway were selected through Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG). The validation of cuprotosis-related genes was conducted through immunofluorescence and western blot analyses.

Results

Totally, 27616 lncRNAs and 2189 mRNAs were observed to be differentially expressed (|Fold Change| ≥ 2 and q< 0.05) after AAA, including 10424 up-regulated and 17192 down-regulated lncRNAs, 1904 up-regulated and 285 down-regulated mRNAs. Gene ontology and KEGG pathway analysis showed that the DElncRNAs and DEmRNAs were implicated in many different biological processes and pathways. Furthermore, Cuprotosis-related genes (NLRP3, FDX1) were upregulated in the AAA samples compared with the normal one.

Conclusion

Cuprotosis-related genes (NLRP3,FDX1) involved in AAA immune environment might be critical for providing new insight into identification of potential targets for AAA therapy.

Clinicoradiological evaluation of oxidative stress activity in acute cerebral infarction in the first 24 h and the qualitative importance of dysfunctional HDL in stroke

BACKGROUND

Acute cerebral infarction (ACI) occurs as a result of instant disruption of vascular flow that causes disbalance between oxidative/antioxidative activity. We examined the relationship of serum neuro-oxidative stress parameters with stroke severity and infarct volume in ACI and emphasized the qualitative importance of high-density lipoprotein (HDL) on its relationship with myeloperoxidase (MPO) and paraoxonase-1 (PON1) in the acute period of stroke.

METHODS

One hundred ACI patients applied within the first 24 h and 50 healthy volunteers were included. The patient group was evaluated with demographic data (including arrival serum biochemical assessment), clinical disability scores, infarct volume, serum oxidative/antioxidative parameters (lipid hydroperoxide (LOOH), MPO, PON1, MPO/PON ratio). The relevant serum parameters were compared with the control group. Dysfunctional HDL measurement was based on detecting dysfunctionality as a result of a high positive correlation between the dysfunctional feature of HDL and the MPO/PON ratio. The correlation of serum parameters, clinical disability score, and infarct volume were evaluated, and independent analyses of variability with comorbidities were performed.

RESULTS

A negative correlation between PON1 and arrival NIH score/scale (NIHSS), LOOH and discharge modified rankin scale (mRS), triglyceride level, and infarct volume; a positive correlation between MPO\PON ratio and infarct volume was determined. Logistic regression analyses showed that hypertension, diabetes, and high HbA1C may be predictors of stroke severity, and diabetes mellitus, high HbA1C, infarct volume, and high NIHSS score may be predictors of early disability (p < 0.005). The ROC curve analysis revealed that determining the cut-off value for LOOH is of importance in determining early disability scores (7.2 and 6.2, respectively).

DISCUSSION

The balance between oxidative and antioxidative stress parameters and their quantitative/qualitative changes is of importance, especially in the acute period of ACI. Dysfunctional HDL's evolution and its relationship with other oxidants are significant not only in the cardiovascular aspect but also in the clinicoradiological aspect.

Comparative analysis of aneurysm subtypes associated genes based on protein-protein interaction network

The arterial aneurysm refers to localized dilation of blood vessel wall and is common in general population. The majority of aneurysm cases remains asymptomatic until a sudden rupture which is usually fatal and of extremely high mortality (~ 50-60%). Therefore, early diagnosis, prevention and management of aneurysm are in urgent need. Unfortunately, current understanding of disease driver genes of various aneurysm subtypes is still limited, and without appropriate biomarkers and drug targets no specialized drug has been developed for aneurysm treatment. In this research, aneurysm subtypes were analyzed based on protein-protein interaction network to better understand aneurysm pathogenesis. By measuring network-based proximity of aneurysm subtypes, we identified a relevant closest relationship between aortic aneurysm and aortic dissection. An improved random walk method was performed to prioritize candidate driver genes of each aneurysm subtype. Thereafter, transcriptomes of 6 human aneurysm subtypes were collected and differential expression genes were identified to further filter potential driver genes. Functional enrichment of above driver genes indicated a general role of ubiquitination and programmed cell death in aneurysm pathogenesis. Especially, we further observed participation of BCL-2-mediated apoptosis pathway and caspase-1 related pyroptosis in the development of cerebral aneurysm and aneurysmal subarachnoid hemorrhage in corresponding transcriptomes.

Obesity-Associated Metabolic Disturbances Reverse the Antioxidant and Anti-Inflammatory Properties of High-Density Lipoproteins in Microglial Cells

High-density lipoproteins (HDLs) play an important role in reverse cholesterol transport and present antioxidant properties, among others. In the central nervous system (CNS), there are HDLs, where these lipoproteins could influence brain health. Owing to the new evidence of HDL functionality remodeling in obese patients, and the fact that obesity-associated metabolic disturbances is pro-inflammatory and pro-oxidant, the aim of this study was to investigate if HDL functions are depleted in obese patients and obesity-associated microenvironment. HDLs were isolated from normal-weight healthy (nwHDL) and obese men (obHDL). The oxHDL level was measured by malondialdehyde and 4-hydroxynoneal peroxided products. BV2 microglial cells were exposed to different concentrations of nwHDL and obHDL in different obesity-associated pro-inflammatory microenvironments. Our results showed that hyperleptinemia increased oxHDL levels. In addition, nwHDLs reduced pro-inflammatory cytokines’ release and M1 marker gene expression in BV2 microglial cells. Nevertheless, both nwHDL co-administered with LPS+leptin and obHDL promoted BV2 microglial activation and a higher pro-inflammatory cytokine production, thus confirming that obesity-associated metabolic disturbances reverse the antioxidant and anti-inflammatory properties of HDLs in microglial cells.

Aortic aneurysm evaluation by scanning acoustic microscopy and Raman spectroscopy

Aortic aneurysm is observed as a result of the extensive alteration in the elasticity of the aortic wall due to the breakdown of elastin and collagen. In this study, we studied the feasibility of scanning acoustic microscopy (SAM) and Raman spectroscopy (RS) in characterizing the dilated segments of the aorta from male and female patients with aortic aneurysm. SAM determined the acoustic property variation in the aorta by calculating the acoustic impedance values of aorta samples of 18 patients. RS determined the disease states by analyzing the chemical variation especially in the peaks related to elastin and collagen using the k-means classification method. Consequently, we assume that combining these two techniques in clinics will help to investigate the dilated segment of the aorta with micrometer resolution, which will reduce the possibility of new aneurysm formation due to a segment not excised during the surgery.

Malondialdehyde-modified HDL particles elicit a specific IgG response in abdominal aortic aneurysm

High Density Lipoprotein (HDL) plays a protective role in abdominal aortic aneurysm (AAA); however, recent findings suggest that oxidative modifications could lead to dysfunctional HDL in AAA. This study aimed at testing the effect of oxidized HDL on aortic lesions and humoral immune responses in a mouse model of AAA induced by elastase, and evaluating whether antibodies against modified HDL can be found in AAA patients. HDL particles were oxidized with malondialdehyde (HDL-MDA) and the changes were studied by biochemical and proteomics approaches. Experimental AAA was induced in mice by elastase perfusion and then mice were treated with HDL-MDA, HDL or vehicle for 14 days. Aortic lesions were studied by histomorphometric analysis. Levels of anti-HDL-MDA IgG antibodies were measured by an in-house immunoassay in the mouse model, in human tissue-supernatants and in plasma samples from the VIVA cohort. HDL oxidation with MDA was confirmed by enhanced susceptibility to diene formation. Proteomics demonstrated the presence of MDA adducts on Lysine residues of HDL proteins, mainly ApoA-I. MDA-modification of HDL abrogated the protective effect of HDL on cultured endothelial cells as well as on AAA dilation in mice. Exposure to HDL-MDA elicited an anti-HDL-MDA IgG response in mice. Anti-HDL-MDA were also detected in tissue-conditioned media from AAA patients, mainly in intraluminal thrombus. Higher plasma levels of anti-HDL-MDA IgG antibodies were found in AAA patients compared to controls. Anti-HDL-MDA levels were associated with smoking and were independent predictors of overall mortality in AAA patients. Overall, MDA-oxidized HDL trigger a specific humoral immune response in mice. Besides, antibodies against HDL-MDA can be detected in tissue and plasma of AAA patients, suggesting its potential use as surrogate stable biomarkers of oxidative stress in AAA.

Apolipoprotein-AI and AIBP synergetic anti-inflammation as vascular diseases therapy: the new perspective

Vascular diseases (VDs) including pulmonary arterial hypertension (PAH), atherosclerosis (AS) and coronary arterial diseases (CADs) contribute to the higher morbidity and mortality worldwide. Apolipoprotein A-I (Apo A-I) binding protein (AIBP) and Apo-AI negatively correlate with VDs. However, the mechanism by which AIBP and apo-AI regulate VDs still remains unexplained. Here, we provide an overview of the role of AIBP and apo-AI regulation of vascular diseases molecular mechanisms such as vascular energy homeostasis imbalance, oxidative and endoplasmic reticulum stress and inflammation in VDs. In addition, the role of AIBP and apo-AI in endothelial cells (ECs), vascular smooth muscle (VSMCs) and immune cells activation in the pathogenesis of VDs are explained. The in-depth understanding of AIBP and apo-AI function in the vascular system may lead to the discovery of VDs therapy.

Altered high-density lipoprotein composition and functions during severe COVID-19

Coronavirus disease 2019 (COVID-19) pandemic is affecting millions of patients worldwide. The consequences of initial exposure to SARS-CoV-2 go beyond pulmonary damage, with a particular impact on lipid metabolism. Decreased levels in HDL-C were reported in COVID-19 patients. Since HDL particles display antioxidant, anti-inflammatory and potential anti-infectious properties, we aimed at characterizing HDL proteome and functionality during COVID-19 relative to healthy subjects. HDLs were isolated from plasma of 8 severe COVID-19 patients sampled at admission to intensive care unit (Day 1, D1) at D3 and D7, and from 16 sex- and age-matched healthy subjects. Proteomic analysis was performed by LC-MS/MS. The relative amounts of proteins identified in HDLs were compared between COVID-19 and controls. apolipoprotein A-I and paraoxonase 1 were confirmed by Western-blot analysis to be less abundant in COVID-19 versus controls, whereas serum amyloid A and alpha-1 antitrypsin were higher. HDLs from patients were less protective in endothelial cells stiumalted by TNFα (permeability, VE-cadherin disorganization and apoptosis). In these conditions, HDL inhibition of apoptosis was blunted in COVID-19 relative to controls. In conclusion, we show major changes in HDL proteome and decreased functionality in severe COVID-19 patients.

Red Blood Cells and Hemoglobin in Human Atherosclerosis and Related Arterial Diseases

As the main particulate component of the circulating blood, RBCs play major roles in physiological hemodynamics and impact all arterial wall pathologies. RBCs are the main determinant of blood viscosity, defining the frictional forces exerted by the blood on the arterial wall. This function is used in phylogeny and ontogeny of the cardiovascular (CV) system, allowing the acquisition of vasomotricity adapted to local metabolic demands, and systemic arterial pressure after birth. In pathology, RBCs collide with the arterial wall, inducing both local retention of their membranous lipids and local hemolysis, releasing heme-Fe⁺⁺ with a high toxicity for arterial cells: endothelial and smooth muscle cells (SMCs) cardiomyocytes, neurons, etc. Specifically, overloading of cells by Fe⁺⁺ promotes cell death. This local hemolysis is an event associated with early and advanced stages of human atherosclerosis. Similarly, the permanent renewal of mural RBC clotting is the major support of oxidation in abdominal aortic aneurysm. In parallel, calcifications promote intramural hemorrhages, and hemorrhages promote an osteoblastic phenotypic shift of arterial wall cells. Different plasma or tissue systems are able, at least in part, to limit this injury by acting at the different levels of this system.

Changes in High-Density Lipoproteins Related to Outcomes in Patients with Acute Stroke

Modifications in high-density lipoprotein (HDL) particle sizes and HDL-binding proteins have been reported in stroke patients. We evaluated whether the lipoprotein profile, HDL composition and functionality were altered in stroke patients according to their clinical outcome using the modified Rankin Score at 3 months. Plasma samples were obtained from stroke patients treated with intravenous thrombolysis. Levels of cardiovascular and inflammatory markers in plasma were measured using the Human CVD Panel 1 (Milliplex^® MAP). Lipoprotein subfractions from plasma were quantified by non-denaturing acrylamide gel electrophoresis, using the Lipoprint^®-System (Quantimetrix^®), and HDLs were isolated by ultracentrifugation. Relative amounts of paraoxonase-1 (PON1) and alpha-1 anti-trypsin (AAT) in the isolated HDLs were determined by Western blot. HDL anti-inflammatory function was evaluated in human blood-brain barrier endothelial cells stimulated with 100 ng/mL TNFα, and HDL antioxidant function was evaluated via their capacity to limit copper-induced low-density lipoprotein oxidation. Stroke patients with unfavorable outcomes had a lower proportion of small-sized HDLs and increased plasma levels of E-selectin (SELE) and the intercellular adhesion molecule 1 (ICAM1). HDLs from patients with unfavorable outcomes had lower levels of PON1 and displayed a blunted capacity to reduce the expression of SELE, interleukin 8 (IL8) and the monocyte chemoattractant protein-1 (MCP1) mRNA induced by TNFα in endothelial cells. These HDLs also had a reduced antioxidant capacity relative to HDLs from healthy donors. In conclusion, an increased ratio of large/small HDLs with impaired anti-inflammatory and antioxidant capacities was associated with unfavorable outcomes in stroke patients. Alteration of HDL functionality was mainly associated with a low amount of PON1 and high amount of AAT.

The Role of a Selective P2Y6 Receptor Antagonist, MRS2578, on the Formation of Angiotensin II-Induced Abdominal Aortic Aneurysms

Objective

The P2Y₆ receptor has been shown to be involved in many cardiovascular diseases, including hypertension and atherosclerosis. The study is aimed at exploring the role of the P2Y₆ receptor in Ang II-induced abdominal aortic aneurysm (AAA) formation in apolipoprotein E-deficient (apoE^−/−) mice by using its selective antagonist.

Methods

Male apoE^−/− mice were fed with high-fat diet and infused with angiotensin (Ang) II (1000 ng/kg/min) for 4 weeks to induce AAA or saline as controls. Mice were divided into four groups: normal saline (NS, placebo control) group (n = 8), Ang II+vehicle (Ang II) group (n = 14), Ang II-low dose MRS2578 (Ang II+MRS-16 mg) group (n = 14), and Ang II-high dose MRS2578 (Ang II+MRS-32 mg) group (n = 14). Daily intraperitoneal injection with vehicle or MRS2578 was pretreated one week before Ang II infusion. On postoperative day 10, aorta imaging of each group was taken by ultrasonography. After 4 weeks of Ang II infusion, the excised aortas were processed for diameter measurement and quantification of aneurysm severity and tissue characteristics; the blood samples were collected for measurement of the lipid profile and levels of cytokines. Verhoeff's Van Gieson (EVG) staining and immunochemistry staining were performed to evaluate disruption of the extracellular matrix (ECM) and infiltration of macrophages. Expression and activity of matrix metalloproteinases (MMPs) was measured by gelatin zymography.

Results

Treatment with MRS2578 made no significant difference in AAA formation, and maximal aortic diameter yet caused higher AAA rupture-induced mortality from 7% (Ang II) to 21.4% (Ang II+MRS-16 mg) or 42.9% (Ang II+MRS-32 mg), respectively (p < 0.05). Consistently, the severity of aneurysm tended to be more deteriorated in MRS2578-treated groups, especially the high-dosage group. The ratios of type III and IV aneurysm were much higher in the MRS2578-coadministered groups (p < 0.05). Furthermore, histological analyses showed that administration of MRS2578 significantly increased infiltration of macrophages, expression of monocyte chemotactic protein 1 (MCP-1) and vascular cell adhesion molecule-1 (VCAM-1), and activities of MMP-2 and MMP-9 followed by aggravating degradation elastin in vivo (p < 0.05). However, the multiple effects of MRS2578 on the development of AAA are independent of changes in systolic blood pressure and lipid profiles.

Conclusions

The present study demonstrated that administration of MRS2578 exacerbated the progression and rupture of experimental AAA through promoting proinflammatory response and MMP expression and activity, which indicated a crucial role of the P2Y₆ receptor in AAA development. Clinical Relevance. Purinergic P2Y receptors have attracted much attention since the P2Y₁₂ receptor antagonist had been successfully applied in clinical practice. Elucidating the underlying mechanisms of AAA and exploring potential therapeutic strategies are essential to prevent its progression and reduce the mortality rate.

Impaired HDL (High-Density Lipoprotein)-Mediated Macrophage Cholesterol Efflux in Patients With Abdominal Aortic Aneurysm-Brief Report

Objective- The ability of HDL (high-density lipoprotein) to promote macrophage cholesterol efflux is considered the main HDL cardioprotective function. Abdominal aortic aneurysm (AAA) is usually characterized by cholesterol accumulation and macrophage infiltration in the aortic wall. Here, we aim to evaluate the composition of circulating HDL particles and their potential for promoting macrophage cholesterol efflux in AAA subjects. Approach and Results- First, we randomly selected AAA and control subjects from Spain. The AAA patients in the Spanish cohort showed lower plasma apoA-I levels concomitantly associated with low levels of plasma HDL cholesterol and the amount of preβ-HDL particles. We determined macrophage cholesterol efflux to apoB-depleted plasma, which contains mature HDL, preβ-HDL particles and HDL regulatory proteins. ApoB-depleted plasma from AAA patients displayed an impaired ability to promote macrophage cholesterol efflux. Next, we replicated the experiments with AAA and control subjects derived from Danish cohort. Danish AAA patients also showed lower apoA-I levels and a defective HDL-mediated macrophage cholesterol efflux. Conclusions- AAA patients show impaired HDL-facilitated cholesterol removal from macrophages, which could be mechanistically linked to AAA.

Myeloperoxidase Associates With Degenerative Remodeling and Rupture of the Saccular Intracranial Aneurysm Wall

Rupture of a saccular intracranial aneurysm (sIA) is often fatal. Thus, early detection of rupture-prone sIAs is vital. Myeloperoxidase (MPO), derived mainly from neutrophils, associates with sIA rupture, and therefore its role in sIA pathogenesis warrants further studies. We analyzed MPO and its association with other histological markers in 36 (16 unruptured and 20 ruptured) sIA samples by immunohistochemistry. MPO was present in all studied sIAs, and its expression associated with wall inflammatory cell infiltrations (r = 0.50, 0.63, and 0.75, all p ≤ 0.002), degenerative remodeling (p = 0.002) and rupture (p = 0.003). MPO associated strongly with the presence of organized luminal thrombi (p < 0.001), which also stained positive for MPO. Polymorphonuclear MPO+ cells were detected in the sIA walls, indicating neutrophils as MPO-source. MPO correlated strongly with accumulation of oxidized lipids (r = 0.67, p < 0.001) and loss of smooth muscle cells (r = -0.68, p < 0.001), suggesting that MPO is a relevant source of oxidative stress leading to cell death in the sIA wall. Furthermore, MPO associated with erythrocyte fragmentation (r = 0.74, p < 0.001) and iron deposition (p = 0.041), 2 outcomes known to amplify MPO-dependent oxidative stress. Taken together, these results suggest that MPO associates with degenerative remodeling predisposing to sIA wall rupture and may serve as a biomarker of a rupture-prone sIA wall.

Plasma Cathepsin S is Associated with High-density Lipoprotein Cholesterol and Bilirubin in Patients with Abdominal Aortic Aneurysms

Background

Cathepsin S (CTSS) is a cysteine protease involved in atherogenesis. We compared the plasma CTSS as well as other biomarkers of atherosclerosis in patients with abdominal aortic aneurysms (AAA) and aortoiliac occlusive disease (AOD), aiming to identify the underlying pathogenic mechanisms of the disease development. Also, we hypothesised that the level of plasma CTSS simultaneously increases with a decrease of plasma high-density lipoprotein cholesterol (HDL-C) values.

Methods

33 patients with AAA and 34 patients with AOD were included in this study.

Results

There was no difference in the level of plasma CTSS between the two analysed groups (p=0.833). In the patients with AAA, the plasma CTSS was correlated with HDL-C (r = -0.377, p = 0.034) and total bilirubin (r =0.500, p = 0.003) while, unexpectedly, it was not correlated with cystatin C (Cys C) (r =0.083, p = 0.652). In the patients with AOD, the plasma CTSS correlated with triglycerides (r = 0.597, p< 0.001), only. When the patients were divided according to HDL-C (with HDL-C ≤0.90 and HDL-C >0.90 mmol/L), the plasma CTSS values differed among these groups (31.27 vs.25.61 μg/L, respectively, p<0.001).

Conclusions

These results provide the first evidence that CTSS negatively correlated with HDL-C and bilirubin in patients with AAA. It is possible that differences in the association of the CTSS and other markers of atherosclerosis can determine whether atherosclerotic aorta will develop dilatation or stenosis.

APOA1 oxidation is associated to dysfunctional high-density lipoproteins in human abdominal aortic aneurysm

Background

High-density lipoproteins (HDL) are a complex mixture of lipids and proteins with vasculoprotective properties. However, HDL components could suffer post-translational modifications (PTMs) under pathological conditions, leading to dysfunctional HDL. We studied whether HDL are modified in abdominal aortic aneurysm (AAA) and the effect on HDL functionality.

Methods

HDL were isolated by ultracentrifugation from AAA tissue (HDL-T) and from plasma of healthy volunteers and then incubated with AAA tissue-conditioned medium (HDL-AAA CM). PTMs from these particles were characterized using Comet-PTM. The ability of HDL-AAA CM for promoting cholesterol efflux was determined ex vivo and in vivo by using J774A.1 [³H]cholesterol-labeled mouse macrophages and after injecting [³H]cholesterol-labeled mouse macrophages and HDL into the peritoneal cavity of wild-type C57BL/6 mice, respectively. Trp50 and Trp108 oxidized forms of APOA1 in HDL incubated with conditioned-medium of activated neutrophils and in plasma of AAA patients and controls were measured by targeted parallel reaction monitoring.

Findings

Oxidation was the most prevalent PTM in apolipoproteins, particularly in APOA1. Trp50 and Trp108 in APOA1 were the residues most clearly affected by oxidation in HDL-T and in HDL-AAA CM, when compared to their controls. In addition, cholesterol efflux was decreased in macrophages incubated with HDL-AAA CM in vitro and a decreased macrophage-to-serum reverse cholesterol transport was also observed in mice injected with HDL-AAA CM. Finally, both oxidized Trp50 and Trp108 forms of APOA1 were increased in HDL incubated with conditioned-medium of activated neutrophils and in plasma of AAA patients in relation to controls.

Interpretation

Oxidative modifications of HDL present in AAA tissue and plasma were closely associated with the loss of vasculoprotective properties of HDL in AAA.

Fund

MINECO, ISCiii-FEDER, CIBERDEM, CIBERCV and LA CAIXA.

Rupture of a Totally Occluded Abdominal Aortic Aneurysm

Totally occluded aortic aneurysm is a rare pathology. The medical history and the evolution are unknown. We present a case of a regularly followed up 60-year-old man with chronic thrombosed aneurysm, presenting with mycotic acute rupture. As an original treatment, the patient was treated by aortic ligation without distal revascularization. A literature review from 1974 to 2015 enhances the contemporary understanding of the pathology, by exploring the thrombus interaction, pressure, and the wall shear stress. The literature review confirms the poor prognosis and concludes of a necessary closer follow-up for chronic occluded aneurysm.

Relationship between aortic wall oxidative stress/proteolytic enzyme expression and intraluminal thrombus thickness indicates a novel pathomechanism in the progression of human abdominal aortic aneurysm

The possibility that oxidative stress promotes degradation of the extracellular matrix and a relationship between intraluminal thrombus (ILT) thickness and proteolytic activity within the abdominal aortic aneurysm (AAA) wall has been suggested. In the present study, the hypothesis that thin ILT is correlated with an increase in oxidative stress-related enzymes and matrix metalloproteinase-9 (MMP-9) expression within the human AAA wall was investigated. We also studied the antioxidant activity of superoxide dismutases, catalase, glutathione peroxidase, glutathione reductase, and thioredoxin within the full-thickness AAA wall and through fluoroimmunohistochemical staining of catalase and MMP-9 expression within the inner and outer media, in relation to ILT thickness. Reactive oxygen species control the degradation and remodeling of the extracellular matrix by up-regulating proteolytic enzymes, such as MMPs. Results showed that oxidative stress and proteolytic enzyme expression were simultaneously, significantly higher within thin thrombus (≤10 mm)-covered aneurysm wall when compared with the wall covered by thick thrombus (≥25 mm). These findings provide the first demonstration, to our knowledge, of a causative link between oxidative stress instigating proteolytic enzyme expression at the tissue level and human AAA development. Presence of a thin circumferential thrombus should always be considered as a risk factor for the greatest increase in aneurysm growth rate and rupture, giving an indication for surgery timing.-Wiernicki, I., Parafiniuk, M., Kolasa-Wołosiuk, A., Gutowska, I., Kazimierczak, A., Clark, J., Baranowska-Bosiacka, I., Szumilowicz, P., Gutowski, P. Relationship between aortic wall oxidative stress/proteolytic enzyme expression and intraluminal thrombus thickness indicates a novel pathomechanism in the progression of human abdominal aortic aneurysm.

Abdominal aortic aneurysms

An abdominal aortic aneurysm (AAA) is a localized dilatation of the infrarenal aorta. AAA is a multifactorial disease, and genetic and environmental factors play a part; smoking, male sex and a positive family history are the most important risk factors, and AAA is most common in men >65 years of age. AAA results from changes in the aortic wall structure, including thinning of the media and adventitia due to the loss of vascular smooth muscle cells and degradation of the extracellular matrix. If the mechanical stress of the blood pressure acting on the wall exceeds the wall strength, the AAA ruptures, causing life-threatening intra-abdominal haemorrhage - the mortality for patients with ruptured AAA is 65-85%. Although AAAs of any size can rupture, the risk of rupture increases with diameter. Intact AAAs are typically asymptomatic, and in settings where screening programmes with ultrasonography are not implemented, most cases are diagnosed incidentally. Modern functional imaging techniques (PET, CT and MRI) may help to assess rupture risk. Elective repair of AAA with open surgery or endovascular aortic repair (EVAR) should be considered to prevent AAA rupture, although the morbidity and mortality associated with both techniques remain non-negligible.

High-Density Lipoprotein Is Associated with Progression of Intracranial Aneurysms

BACKGROUND

We tested the hypothesis that high-density lipoprotein (HDL) is associated with intracranial aneurysm growth and rupture.

METHODS

We used an observational cohort study design. Age, sex, admission systolic blood pressure (SBP), diabetes, hypertension, coronary artery disease, aneurysmal rupture, apolipoprotein (APO)-A1, APO-B, HDL, low-density lipoprotein, triglycerides, cholesterol, and aneurysm location and size were recorded. Aneurysms <8 mm were categorized as small.

RESULTS

The data from 581 patients with intracranial aneurysms were analyzed. The predictive factors for small size of aneurysms were female sex (odds ratio [OR], 0.630; 95% confidence interval [CI], 0.428-0.927; P = 0.019) and higher HDL (OR, 0.327; 95% CI, 0.159-0.672; P = 0.0002). In the subgroup of male patients, lower HDL was the only risk factor for large size (P = 0.015). The predictors of aneurysmal rupture were small size (OR, 0.875; 95% CI, 0.842-0.910; P = 0.000), higher HDL (OR, 3.716; 95% CI, 1.623-8.509; P = 0.002), no coronary artery disease (OR, 4.736; 95% CI, 1.528-14.681; P = 0.007), lower APO-A1 (OR, 0.202; 95% CI, 0.064-0.641; P = 0.007), and higher admission SBP (OR, 1.024; 95% CI, 1.015-1.032; P = 0.000). An HDL/aneurysm size ratio >0.31 was associated with a 46.2-fold increased likelihood of aneurysmal rupture (OR, 46.214; 95% CI, 13.386-159.548; P = 0.002).

CONCLUSIONS

The HDL level was inversely associated with intracranial aneurysm growth, especially in men. Higher HDL levels and small aneurysm size contributed to a greater risk of aneurysmal rupture. An HDL/size ratio >0.31 was a valuable predictor of intracranial rupture.

Chinese Herbal Medicine as a Potential Treatment of Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is an irreversible condition where the abdominal aorta is dilated leading to potentially fatal consequence of aortic rupture. Multiple mechanisms are involved in the development and progression of AAA, including chronic inflammation, oxidative stress, vascular smooth muscle (VSMC) apoptosis, immune cell infiltration and extracellular matrix (ECM) degradation. Currently surgical therapies, including minimally invasive endovascular aneurysm repair (EVAR), are the only viable interventions for AAAs. However, these treatments are not appropriate for the majority of AAAs, which measure <50 mm. Substantial effort has been invested to identify and develop pharmaceutical treatments such as statins and doxycycline for this potentially lethal condition but these interventions failed to offer a cure or to retard the progression of AAA. Chinese herbal medicine (CHM) has been used for the management of cardiovascular diseases for thousands of years in China and other Asian countries. The unique multi-component and multi-target property of CHMs makes it a potentially ideal therapy for multifactorial diseases such as AAA. In this review, we review the current scientific evidence to support the use of CHMs for the treatment of AAA. Mechanisms of action underlying the effects of CHMs on AAA are also discussed.

Reactive Oxygen Species, Superoxide Dimutases, and PTEN-p53-AKT-MDM2 Signaling Loop Network in Mesenchymal Stem/Stromal Cells Regulation

Mesenchymal stromal/stem cells (MSCs) are multipotent cells that can differentiate to various specialized cells, which have the potential capacity to differentiate properly and accelerate recovery in damaged sites of the body. This stem cell technology has become the fundamental element in regenerative medicine. As reactive oxygen species (ROS) have been reported to adversely influence stem cell properties, it is imperative to attenuate the extent of ROS to the promising protective approach with MSCs’ regenerative therapy. Oxidative stress also affects the culture expansion and longevity of MSCs. Therefore, there is great need to identify a method to prevent oxidative stress and replicative senescence in MSCs. Phosphatase and tensin homologue deleted on chromosome 10/Protein kinase B, PKB (PTEN/AKT) and the tumor suppressor p53 pathway have been proven to play a pivotal role in regulating cell apoptosis by regulating the oxidative stress and/or ROS quenching. In this review, we summarize the current research and our view of how PTEN/AKT and p53 with their partners transduce signals downstream, and what the implications are for MSCs’ biology.

Circulating Concentrations of Redox Biomarkers Do Not Improve the Prediction of Adverse Cardiovascular Events in Patients With Type 2 Diabetes Mellitus

Background

Despite pathophysiological relevance and promising experimental data, the usefulness of biomarkers of oxidative stress for cardiac risk prediction is unclear. The aim of our study was to investigate the prognostic value of 6 biomarkers exploring different pathways of oxidative stress for predicting adverse cardiovascular outcomes in patients with type 2 diabetes mellitus beyond established risk factors.

Methods and Results

The SURDIAGENE (Survie, Diabete de type 2 et Genetique) prospective cohort study consecutively recruited 1468 patients with type 2 diabetes mellitus. Assays were performed at baseline, and incident cases of major adverse cardiovascular events (MACE)—first occurrence of cardiovascular death, nonfatal myocardial infarction, or stroke—were recorded during a median of 64 months. Advanced oxidation protein products, oxidative hemolysis inhibition assay, ischemia‐modified albumin, and total reductive capacity of plasma were not associated with the risk of MACE in univariate analyses. Fluorescent advanced glycation end products and carbonyls were associated with MACE (hazard ratio=1.38 per SD, 95% confidence interval 1.24‐1.54, P<0.001 and hazard ratio=1.15 per SD, 95% confidence interval 1.04‐1.27, P=0.006, respectively) in univariate analysis, but when added to a multivariate predictive model including traditional risk factors for MACE, these markers did not significantly improve c‐statistics or integrated discrimination index of the model.

Conclusions

These plasma concentrations of 6 markers, which cover a broad spectrum of oxidative processes, were not significantly associated with MACE occurrence and were not able to improve MACE risk discrimination and classification beyond classical risk factors in type 2 diabetes mellitus patients.

From tissue iron retention to low systemic haemoglobin levels, new pathophysiological biomarkers of human abdominal aortic aneurysm

Iron deposits are observed in tissue of abdominal aortic aneurysm (AAA) patients, although the underlying mechanisms are not completely elucidated. Therefore we explored circulating markers of iron metabolism in AAA patients, and tested if they could serve as biomarkers of AAA. Increased red blood cell (RBC)-borne iron retention and transferrin, transferrin receptor and ferritin expression was observed in AAA tissue compared to control aorta (immunohistochemistry and western blot). In contrast, decreased circulating iron, transferrin, mean corpuscular haemoglobin concentration (MCHC) and haemoglobin concentration, along with circulating RBC count, were observed in AAA patients (aortic diameter >3 cm, n=114) compared to controls (aortic diameter <3 cm, n=88) (ELISA), whereas hepcidin concentrations were increased in AAA subjects (MS/MS assay). Moreover, iron, transferrin and haemoglobin levels were negatively, and hepcidin positively, correlated with aortic diameter in AAA patients. The association of low haemoglobin with AAA presence or aortic diameter was independent of specific risk factors. Moreover, MCHC negatively correlated with thrombus area in another cohort of AAA patients (aortic diameter 3–5 cm, n=357). We found that anaemia was significantly more prevalent in AAA patients (aortic diameter >5 cm, n=8,912) compared to those in patients with atherosclerotic aorto-iliac occlusive disease (n=17,737) [adjusted odds ratio=1.77 (95% confidence interval: 1.61;1.93)]. Finally, the mortality risk among AAA patients with anaemia was increased by almost 30% [adjusted hazard ratio: 1.29 (95% confidence interval: 1.16;1.44)] as compared to AAA subjects without anaemia. In conclusion, local iron retention and altered iron recycling associated to high hepcidin and low transferrin systemic concentrations could lead to reduced circulating haemoglobin levels in AAA patients. Low haemoglobin levels are independently associated to AAA presence and clinical outcome.

ApoA-I/HDL-C levels are inversely associated with abdominal aortic aneurysm progression

Abdominal aortic aneurysm (AAA) evolution is unpredictable, and there is no therapy except surgery for patients with an aortic size > 5 cm (large AAA). We aimed to identify new potential biomarkers that could facilitate prognosis and treatment of patients with AAA. A differential quantitative proteomic analysis of plasma proteins was performed in AAA patients at different stages of evolution [small AAA (aortic size=3�5cm) vs large AAA] using iTRAQ labelling, highthroughput nano-LC-MS/MS and a novel multi-layered statistical model. Among the proteins identified, ApoA-I was decreased in patients with large AAA compared to those with small AAA. These results were validated by ELISA on plasma samples from small (n=90) and large AAA (n=26) patients (150 ± 3 vs 133 ± 5 mg/dl, respectively, p< 0.001). ApoA-I levels strongly correlated with HDL-Cholesterol (HDL-C) concentration (r=0.9, p< 0.001) and showed a negative correlation with aortic size (r=-0.4, p< 0.01) and thrombus volume (r=-0.3, p< 0.01), which remained significant after adjusting for traditional risk factors. In a prospective study, HDL-C independently predicted aneurysmal growth rate in multiple linear regression analysis (n=122, p=0.008) and was inversely associated with need for surgical repair (Adjusted hazard ratio: 0.18, 95 % confidence interval: 0.04�0.74, p=0.018). In a nation-wide Danish registry, we found lower mean HDL-C concentration in large AAA patients (n=6,560) compared with patients with aorto-iliac occlusive disease (n=23,496) (0.89 ± 2.99 vs 1.59 ± 5.74 mmol/l, p< 0.001). Finally, reduced mean aortic AAA diameter was observed in AngII-infused mice treated with ApoA-I mimetic peptide compared with saline-injected controls. In conclusion, ApoAI/ HDL-C systemic levels are negatively associated with AAA evolution. Therapies targeting HDL functionality could halt AAA formation.

High-density lipoprotein therapy inhibits Porphyromonas gingivalis-induced abdominal aortic aneurysm progression

Clinical and experimental studies have highlighted the potential implication of periondontal bacteria contamination in the pathogenesis of abdominal aortic aneurysms (AAA). In addition to their role in reverse cholesterol transport, high-density lipoproteins (HDLs) display multiple functions, including anti-inflammatory and lipopolysaccharide scavenging properties. Low plasma levels of HDL-cholesterol have been reported in AAA patients. We tested the effect of a HDL therapy in Sprague-Dawley rat model of AAA, obtained by intraluminal elastase infusion followed by repeated injections of Porphyromonas gingivalis (Pg). HDLs, isolated by ultracentrifugation of plasma from healthy human volunteers, were co-injected intravenously (10 mg/kg) with Pg (1.107 Colony Forming Unit) one, eight and 15 days after elastase perfusion. Rats were sacrificed one week after the last injection. Our results show that Pg injections promote the formation of a persistent neutrophil-rich thrombus associated with increased aortic diameter in this AAA model. HDLs significantly reduced the increased AAA diameter induced by Pg. Histology showed the onset of a healing process in the Pg/HDL group. HDL injections also reduced neutrophil activation in Pg-injected rats associated with decreased cytokine levels in conditioned media and plasma. Scintigraphic analysis showed an intense uptake of 99mTc-HDL by the AAA suggesting that HDLs could exert their beneficial effect by acting directly on the thrombus components. HDL supplementation may therefore constitute a new therapeutic tool for AAA treatment.

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

Oxidative Stress in Human Atherothrombosis: Sources, Markers and Therapeutic Targets

Atherothrombosis remains one of the main causes of morbidity and mortality worldwide. The underlying pathology is a chronic pathological vascular remodeling of the arterial wall involving several pathways, including oxidative stress. Cellular and animal studies have provided compelling evidence of the direct role of oxidative stress in atherothrombosis, but such a relationship is not clearly established in humans and, to date, clinical trials on the possible beneficial effects of antioxidant therapy have provided equivocal results. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is one of the main sources of reactive oxygen species (ROS) in human atherothrombosis. Moreover, leukocyte-derived myeloperoxidase (MPO) and red blood cell-derived iron could be involved in the oxidative modification of lipids/lipoproteins (LDL/HDL) in the arterial wall. Interestingly, oxidized lipoproteins, and antioxidants, have been analyzed as potential markers of oxidative stress in the plasma of patients with atherothrombosis. In this review, we will revise sources of ROS, focusing on NADPH oxidase, but also on MPO and iron. We will also discuss the impact of these oxidative systems on LDL and HDL, as well as the value of these modified lipoproteins as circulating markers of oxidative stress in atherothrombosis. We will finish by reviewing some antioxidant systems and compounds as therapeutic strategies to prevent pathological vascular remodeling.

Erythrocyte Efferocytosis by the Arterial Wall Promotes Oxidation in Early-Stage Atheroma in Humans

Background

Since red blood cells (RBCs) are the predominant cellular blood component interacting with the arterial wall, we explored the role of RBCs efferocytosis by vascular smooth muscle cells (vSMCs) in the initiation of human atheroma.

Methods and results

The comparison of human healthy aortas with aortic fatty streaks or fibroatheromas revealed that RBC angiophagy is implicated from the earliest stages of atherogenesis, as documented by the concomitant detection of redox-active iron, hemoglobin, glycophorin A, and ceroids. RBCs infiltration in the arterial wall was associated with local lipid and protein oxidation, as well as vascular response (expression of heme oxygenase-1 and of genes related to iron metabolism as well as those encoding for phagocytosis). These effects were recapitulated in vitro when vSMCs were co-cultured with phosphatidyl-exposing senescent (s) RBCs but not with fresh RBCs. VSMCs engulfing sRBC increased their intracellular iron content, accumulated hemoglobin, lipids, and activated their phagolysosomes. Strikingly, injections of sRBCs into rats promoted iron accumulation in the aortic wall. In rabbits, hypercholesterolemia increased circulating senescent RBCs and induced the subendothelial accumulation of iron-rich phagocytic foam cells. RBCs bring cholesterol and iron/heme into the vascular wall and interact with vSMCs that phagocytize them.

Conclusion

This study presents a previously unforeseen mechanism of plaque formation that implicates intimal RBC infiltration as one of the initial triggers for foam cell formation and intimal oxidation. Pathogenic effects exerted by several metabolic and hemodynamic factors may rely on their effect on RBC biology, thereby impacting how RBCs interact with the vascular wall.

The pleiotropic vasoprotective functions of high density lipoproteins (HDL)

The pleiotropic functions of circulating high density lipoprotein (HDL) on peripheral vascular health are well established. HDL plays a pivotal role in reverse cholesterol transport and is also known to suppress inflammation, endothelial activation and apoptosis in peripheral vessels. Although not expressed in the central nervous system, HDL has nevertheless emerged as a potential resilience factor for dementia in multiple epidemiological studies. Animal model data specifically support a role for HDL in attenuating the accumulation of β-amyloid within cerebral vessels concomitant with reduced neuroinflammation and improved cognitive performance. As the vascular contributions to dementia are increasingly appreciated, this review seeks to summarize recent literature focused on the vasoprotective properties of HDL that may extend to cerebral vessels, discuss potential roles of HDL in dementia relative to brain-derived lipoproteins, identify gaps in current knowledge, and highlight new opportunities for research and discovery.

High density lipoproteins are modulators of protease activity: Implications in inflammation, complement activation, and atherothrombosis

High density lipoproteins (HDL) represent a compositionally diverse population of particles in the circulation, containing a wide variety of lipids and proteins. Gene ontology functional analysis of the 96 commonly identified HDL binding proteins reveals that almost half of these proteins are either proteases or have known roles in protease regulation. Here, we discuss the activities of some of these proteins in regard to their roles in regulating proteases involved in inflammation, coagulation, and complement activation, particularly in the context of atherosclerosis. The overall goal of this review is to discuss potential functional roles of HDL in protease regulatory pathways based on current literature and known functions of HDL binding proteins and to promote the consideration of HDL as a global modulator of proteolytic equilibrium.

Quantitative HDL Proteomics Identifies Peroxiredoxin-6 as a Biomarker of Human Abdominal Aortic Aneurysm

High-density lipoproteins (HDLs) are complex protein and lipid assemblies whose composition is known to change in diverse pathological situations. Analysis of the HDL proteome can thus provide insight into the main mechanisms underlying abdominal aortic aneurysm (AAA) and potentially detect novel systemic biomarkers. We performed a multiplexed quantitative proteomics analysis of HDLs isolated from plasma of AAA patients (N = 14) and control study participants (N = 7). Validation was performed by western-blot (HDL), immunohistochemistry (tissue), and ELISA (plasma). HDL from AAA patients showed elevated expression of peroxiredoxin-6 (PRDX6), HLA class I histocompatibility antigen (HLA-I), retinol-binding protein 4, and paraoxonase/arylesterase 1 (PON1), whereas α-2 macroglobulin and C4b-binding protein were decreased. The main pathways associated with HDL alterations in AAA were oxidative stress and immune-inflammatory responses. In AAA tissue, PRDX6 colocalized with neutrophils, vascular smooth muscle cells, and lipid oxidation. Moreover, plasma PRDX6 was higher in AAA (N = 47) than in controls (N = 27), reflecting increased systemic oxidative stress. Finally, a positive correlation was recorded between PRDX6 and AAA diameter. The analysis of the HDL proteome demonstrates that redox imbalance is a major mechanism in AAA, identifying the antioxidant PRDX6 as a novel systemic biomarker of AAA.

Dysfunctional HDL in acute stroke

BACKGROUND AND AIMS

HDL-cholesterol concentration is a reliable negative risk factor for acute cerebral infarction (ACI). Beyond quantitative aspects, our aim was to determine whether lipoprotein profiles and HDL functionality were altered at the acute phase of ischemic stroke.

METHODS

Blood was taken from ACI patients within 4.5 h of symptom onset. Lipoproteins were separated by electrophoresis for determination of particle size. HDLs were isolated from plasma of patients (n = 10) and controls (n = 10) by ultracentrifugation. The relative amounts of paraoxonase 1 (PON1), α1antitrypsin (AAT) and myeloperoxidase (MPO) were determined by Western blot. HDL functional assays were performed on human-brain endothelial cells stimulated with TNFα.

RESULTS

Stroke patients had higher proportion of large HDL particles relative to controls (37.8 ± 11.8 vs. 28.4 ± 6.6, p = 0.04). HDLs from patients contained significantly less ApoA1 (1.63 ± 0.42 vs. 2.54 ± 0.71 mg/mL, p = 0.0026) and PON1 (4598 ± 1921 vs. 6598 ± 1127 AU, p = 0.01) than those from controls, whereas MPO and AAT were more abundant in HDLs isolated from ACI patients (respectively 3657 ± 1457 vs. 2012 ± 1234 and 3347 ± 917 vs. 2472 ± 470 AU, p = 0.014 and p = 0.015). HDLs reduced the expression of VCAM1, MCP1 and MMP3 mRNA induced by TNFα in blood-brain barrier endothelial cells. HDLs from patients were less effective in inhibiting TNFα-induced transcription of these genes (respectively 38.6 vs. 55.6% for VCAM1, p = 0.047, 44 vs. 48.1% for MCP1, p = 0.015 and 70 vs. 74% for MMP3, p = 0.024).

CONCLUSIONS

ACI may be associated with a modified distribution of HDL particles (increased proportion of large particles) and HDL-binding proteins, resulting in an inappropriate protection of endothelial cells under ischemic conditions.

Paraoxonase-1 overexpression prevents experimental abdominal aortic aneurysm progression

Decreased paraoxonase-1 (PON1) activity is associated with human and experimental abdominal aortic aneurysm (AAA). Overexpression of PON1 protected mice from AAA development induced by elastase, decreasing oxidative stress, apoptosis and inflammation. PON1 may provide a novel therapeutic target for AAA prevention.

Endogenous superoxide dismutase activation by oral administration of riboflavin reduces abdominal aortic aneurysm formation in rats

OBJECTIVE

Vitamin B2 (riboflavin) reportedly has an antioxidant effect through superoxide dismutase (SOD) activation. However, the effect of riboflavin on abdominal aortic aneurysm (AAA) has never been investigated. In the present study, we examined the hypothesis that riboflavin has a protective effect on AAA formation in an experimental rat model.

METHODS

The AAA model, which was induced with intraluminal elastase and extraluminal calcium chloride, was created in 36 rats. The 36 rats were divided into a riboflavin group (group R; 25 mg/kg/d), and control group (carboxymethyl cellulose). Riboflavin administration by gastric gavage once per day was started at 3 days before aneurysm preparation. On day 3, SOD activity in aneurysm walls was assayed. On day 7, reactive oxygen species (ROS) levels were semiquantified by dihydroethidium staining, and the oxidation product of DNA produced by ROS, 8-hydroxydeoxyguanosine (8-OHdG), was measured by immunohistochemical staining. Histopathologic examination (hematoxylin/eosin and elastica Van Gieson staining) was performed on day 28, and the AAA dilatation ratio was calculated to evaluate the protective effect of riboflavin.

RESULTS

On day 3, SOD activity was significantly increased in aneurysm walls by riboflavin administration (370 ± 204 U/mL in normal, 334 ± 86 U/mL in control, 546 ± 143 U/mL in group R; P = .021). On day 7, ROS levels and 8-OHdG-positive cells in aneurysm walls were significantly decreased by riboflavin treatment (ROS levels: 1.0 ± 0.1 in normal, 4.5 ± 0.4 in control, 3.1 ± 0.5 in group R, P < .01; 8-OHdG-positive cells: 30 ± 2 cells in normal, 148 ± 20 cells in control, 109 ± 15 cells in group R, P < .01). Riboflavin treatment significantly reduced matrix metalloproteinase (MMP)-9 messenger RNA expression in aneurysm walls (relative expression: MMP-9: 0.4 ± 0.7 in normal, 2.6 ± 1.3 in control, 0.5 ± 0.3 in group R, P < .01). On day 28, the aortic walls were less dilated and had higher elastin content in group R than in control (dilatation ratio: 194.9% ± 10.9% in control, 158.6% ± 2.5% in group R; P <.01).

CONCLUSIONS

Riboflavin treatment prevents AAA formation in a rat model through an antioxidant effect and might be a potent pharmacologic agent for AAA treatment in clinical practice.

High-density lipoprotein: a novel target for antirestenosis therapy

Restenosis is an integral pathological process central to the recurrent vessel narrowing after interventional procedures. Although the mechanisms for restenosis are diverse in different pathological conditions, endothelial dysfunction, inflammation, vascular smooth muscle cell (SMC) proliferation, and myofibroblasts transition have been thought to play crucial role in the development of restenosis. Indeed, there is an inverse relationship between high-density lipoprotein (HDL) levels and risk for coronary heart disease (CHD). However, relatively studies on the direct assessment of HDL effect on restenosis are limited. In addition to involvement in the cholesterol reverse transport, many vascular protective effects of HDL, including protection of endothelium, antiinflammation, antithrombus actions, inhibition of SMC proliferation, and regulation by adventitial effects may contribute to the inhibition of restenosis, though the exact relationships between HDL and restenosis remain to be elucidated. This review summarizes the vascular protective effects of HDL, emphasizing the potential role of HDL in intimal hyperplasia and vascular remodeling, which may provide novel prophylactic and therapeutic strategies for antirestenosis.

Deciphering the stromal and hematopoietic cell network of the adventitia from non-aneurysmal and aneurysmal human aorta

Aneurysm is associated to a complex remodeling of arteries that affects all their layers. Although events taking place in the intima and the media have received a particular attention, molecular and cellular events taking place in the adventitia have started to be deciphered only recently. In this study, we have precisely described the composition and distribution of stromal and hematopoietic cells in human arterial adventitia, both at steady state and in the setting of aortic aneurysm. Using polychromatic immunofluorescent and flow cytometry analyses, we observed that unlike the medial layer (which comprises mostly macrophages and T cells among leukocytes), the adventitia comprises a much greater variety of leukocytes. We observed an altered balance in macrophages subsets in favor of M2-like macrophages, an increased proliferation of macrophages, a greater number of all stromal cells in aneurysmal aortas. We also confirmed that in this pathological setting, adventitia comprised blood vessels and arterial tertiary lymphoid organs (ATLOs), which contained also M-DC8⁺ dendritic cells (slanDCs) that could participate in the induction of T-cell responses. Finally, we showed that lymphatic vessels can be detected in aneurysmal adventitia, the functionality of which will have to be evaluated in future studies. All together, these observations provide an integrative outlook of the stromal and hematopoietic cell network of the human adventitia both at steady state and in the context of aneurysm.