Topological determinants and consequences of adventitial responses to arterial wall injury

The clinical relevance of the reversal of coronary atherosclerotic plaque

Atherosclerotic cardiovascular disease (ASCVD) remains a leading cause of death globally despite advances in preventive therapies. Understanding of the initiation and progression of atherosclerosis, the interplay between lipoproteins, endothelial dysfunction, inflammation, and immune responses is critical to treating this disease. The development of vulnerable coronary plaques prone to thrombosis, can lead to acute coronary syndromes, for these reasons, the potential plaque stabilization and regression through pharmacological interventions, particularly lipid-lowering agents like statins and PCSK9 inhibitors is crucial. The imaging techniques such as intravascular ultrasound (IVUS), near-infrared spectroscopy (NIRS), and optical coherence tomography (OCT) play a key role in assessing plaque composition and guiding interventional therapeutic strategies. Clinical evidence supports the efficacy of intensive lipid-lowering therapy in inducing plaque regression, with studies demonstrating reductions in plaque volume and improvements in plaque morphology assessed by IVUS, OCT and NIRS. While pharmacological interventions show promise in promoting plaque regression and stabilization, their impact on long-term cardiovascular events requires further investigation. Multimodality imaging and comprehensive outcome trials are proposed as essential tools for elucidating the relationship between plaque modification and clinical benefit in coronary atherosclerosis. The stabilization or regression of atherosclerotic plaque might serve as the phenomenon linking the reduction in LDL-C levels to the decrease in cardiovascular events. Overall, this review emphasizes the ongoing efforts to advance our understanding of ASCVD pathophysiology and optimize therapeutic approaches for improving patient outcomes.

Temsirolimus Adventitial Delivery to Improve ANGiographic Outcomes Below the Knee

BACKGROUND

Current endovascular treatments of below the knee (BTK) popliteal or tibial/peroneal arteries including investigational drug-coated balloons have limited long-term efficacy.

OBJECTIVES

This Phase 2 trial assessed the feasibility of adventitial deposition of temsirolimus to reduce neointimal hyperplasia and clinically relevant target lesion failure (CR-TLF) 6 months after BTK arterial revascularization.

METHODS

This prospective, multicenter, double-blinded, comparative, dose-escalation trial enrolled 61 patients with Rutherford 3 to 5 symptoms undergoing endovascular revascularization of ≥1 angiographically significant BTK lesions. Perivascular infusion after completion of arterial revascularization was randomized into control (saline) vs low-dose (0.1 mg/mL) temsirolimus groups for the first 30 patients. In the second part of the trial, patients were randomized to control versus high-dose (0.4 mg/mL) temsirolimus groups. Primary and secondary efficacy endpoints were target lesion (TL) transverse-view vessel area loss percentage (TVAL%) and CR-TLF at 6 months, respectively. CR-TLF was defined as a composite of ischemia-driven major amputation of the target limb, clinically driven target lesion revascularization (CD-TLR), and clinically relevant TL occlusion. The primary safety endpoint was freedom from major adverse limb events or perioperative death (MALE+POD) at 30 days.

RESULTS

There was no discernable difference in effect between temsirolimus doses; therefore, the low- and high-dose cohorts were pooled for the analyses. The principal analysis on the per protocol (PP) group of 53 patients revealed superior primary efficacy of the treatment arm, with reduction in TVAL% of 13.9% absolute (37.3% relative) and the rate of CR-TLF reduced by 27.1% absolute (51.3% relative), at 6 months. Subgroup analysis of all Trans-Atlantic Inter-Society Consensus (TASC) B to D lesions (N=36) revealed TVAL% reduction of 22.3% absolute (48.3% relative) and the rate of CR-TLF reduced by 39.2% absolute (56.6% relative). Freedom from 30-day MALE+POD was 100% in all groups.

CONCLUSIONS

This hypothesis-generating trial suggests that adventitial infusion of temsirolimus in BTK arteries improves TVAL% and CR-TLF with no adverse safety signals through 6 months, supporting the move to a Phase 3 trial.

CLINICAL IMPACT

There remain gaps in the endovascular treatment of patients with atherosclerotic lesions of below-the-knee (BTK) arteries. The TANGO trial evaluated the use of sub-adventitial temsirolimus with the Bullfrog micro-infusion device during BTK interventions. The therapy was safe and effective. Compared with controls, vessel lumen area patency was improved, and target lesion failure was less frequent. The effects were most appreciable in subjects with higher baseline TASC lesions (B, C, or D). Sub-adventitial temsirolimus offers the potential to improve the results of BTK interventions in this challenging patient population.

The natural polyphenol fisetin in atherosclerosis prevention: a mechanistic review

The incidence and mortality rate of atherosclerotic cardiovascular disease (ASCVD) is increasing yearly worldwide. Recently, a growing body of evidence has unveiled the anti-atherosclerotic properties of fisetin, a natural polyphenol compound. In this article, we reviewed the pharmacologic actions of fisetin on experimental atherosclerosis and its protective effects on disease-relevant cell types such as endothelial cells, macrophages, vascular smooth muscle cells, and platelets. Based on its profound cardiovascular actions, fisetin holds potential for clinical translation and could be developed as a potential therapeutic option for atherosclerosis and its related complications. Large-scale randomized clinical trials are warranted to ascertain the safety and efficacy of fisetin in patients with or high risk for ASCVD.

Chronic Administration of Methamphetamine Aggravates Atherosclerotic Vulnerable Plaques in Apolipoprotein E Knockout Mice Fed with a High-cholesterol Diet

BACKGROUND

It has been observed previously that chronic methamphetamine (METH) administration could upregulate neuropeptide Y (NPY) expression and promote atherosclerotic formation in apolipoprotein E knockout (ApoE-/-) mice fed with a normal cholesterol or high diet and NPY might be involved in the pathogenesis of METHinduced atherogenic effects through NPY Y1 receptor pathway. Vulnerable coronary atherosclerotic plaque (VP) is a critical pathological finding responsible for the acute coronary syndrome (ACS). In this study, we explored whether METH abuse could aggravate the formation of VP in ApoE-/- mice fed with high cholesterol diet.

OBJECTIVE

The purpose of this study was to observe if chronic METH administration could aggravate vulnerable plaque (VP) formation in ApoE-/- mice fed with a highcholesterol diet.

METHODS

Male ApoE-/- mice fed with a high-cholesterol diet were intraperitoneally injected with normal saline (NS) or 8 mg/kg/day METH (M8) for 24 weeks. Body weight was monitored from baseline to 24 weeks at 2 weeks intervals. After 24 weeks of treatment, plasma lipid variables were measured. Movat's staining and immunohistochemical staining were performed on frozen sections of the aortic roots to calculate VP percentage and intraplaque hemorrhage (IPH) percentage and detect expression of NPY, vascular endothelial growth factor (VEGF), and CD31. In vitro, the expressions of Y2R, VEGF, and CD31 were detected by immunofluorescence staining in aortic endothelial cells incubated with PBS, 100μM METH, 10nmol NPY, or 100μM METH plus 10nmol NPY for 12 hours.

RESULTS

The CD31 positive area, percentage of IPH, VP, and the expressions of NPY and VEGF were significantly increased in the M8 group than in the NS group. In vitro, the expressions of Y2R, VEGF, and CD31 were significantly increased in the METH+NPY group than in the PBS, METH, and NPY groups and these effects could be blunted by treatment with a Y2R antagonist or DPPIV inhibitor.

CONCLUSION

Chronic METH administration could aggravate VP in ApoE-/- mice fed with a high-cholesterol diet, possibly through upregulating vascular NPY and VEGF expression and promoting angiogenesis and vessel rupture in atherosclerotic plaques. Our findings indicated that increased VP formation might contribute to the development of acute coronary syndrome post-chronic METH abuse by activating DPPIV/NPY/Y2R pathway.

Metabolic changes with the occurrence of atherosclerotic plaques and the effects of statins

Atherosclerosis is a common cardiovascular disease caused by the abnormal expression of multiple factors and genes influenced by both environmental and genetic factors. The primary manifestation of atherosclerosis is plaque formation, which occurs when inflammatory cells consume excess lipids, affecting their retention and modification within the arterial intima. This triggers endothelial cell (EC) activation, immune cell infiltration, vascular smooth muscle cell (VSMC) proliferation and migration, foam cell formation, lipid streaks, and fibrous plaque development. These processes can lead to vascular wall sclerosis, lumen stenosis, and thrombosis. Immune cells, ECs, and VSMCs in atherosclerotic plaques undergo significant metabolic changes and inflammatory responses. The interaction of cytokines and chemokines secreted by these cells leads to the onset, progression, and regression of atherosclerosis. The regulation of cell- or cytokine-based immune responses is a novel therapeutic approach for atherosclerosis. Statins are currently the primary pharmacological agents utilised for managing unstable plaques owing to their ability to enhance endothelial function, regulate VSMC proliferation and apoptosis by reducing cholesterol levels, and mitigate the expression and activity of inflammatory cytokines. In this review, we provide an overview of the metabolic changes associated with atherosclerosis, describe the effects of inflammatory responses on atherosclerotic plaques, and discuss the mechanisms through which statins contribute to plaque stabilisation. Additionally, we examine the role of statins in combination with other drugs in the management of atherosclerosis.

Giant cell arteritis: reviewing the advancing diagnostics and management

Giant Cell Arteritis (GCA) is well known to be a critical ischaemic disease that requires immediate medical recognition to initiate treatment and where one in five people still suffer visual loss. The immunopathophysiology has continued to be characterised, and the influencing of ageing in the development of GCA is beginning to be understood. Recent national and international guidelines have supported the directed use of cranial ultrasound to reduce diagnostic delay and improve clinical outcomes. Immediate high dose glucocorticoids remain the standard emergency treatment for GCA, with a number of targeted agents that have been shown in clinical trials to have superior clinical efficacy and steroid sparing effects. The aim of this review was to present the latest advances in GCA that have the potential to influence routine clinical practice.

Adenosine signaling as target in cardiovascular pharmacology

Increasing evidence demonstrated the relevance of adenosine system in the onset and development of cardiovascular diseases, such as hypertension, myocardial infarct, ischemia, hypertension, heart failure, and atherosclerosis. In this regard, intense research efforts are being focused on the characterization of the pathophysiological significance of adenosine, acting at its membrane receptors named A1, A2A, A2B, and A3 receptors, in cardiovascular diseases. The present review article provides an integrated and comprehensive overview about current clinical and pre-clinical evidence about the role of adenosine in the pathophysiology of cardiovascular diseases. Particular attention has been focused on current scientific evidence about the pharmacological ligands acting on adenosine pathway as useful tools to manage cardiovascular diseases.

Changes in transmural mass transport correlate with ascending thoracic aortic aneurysm diameter in a fibulin-4 E57K knockin mouse model

Thoracic aortic aneurysm is characterized by dilation of the aortic diameter by greater than 50%, which can lead to dissection or rupture. Common histopathology includes extracellular matrix remodeling that may affect transmural mass transport, defined as the movement of fluids and solutes across the wall. We measured in vitro ascending thoracic aorta mass transport in a mouse model with partial aneurysm phenotype penetration due to a mutation in the extracellular matrix protein fibulin-4 [Fbln4E57K/E57K, referred to as MU-A (aneurysm) or MU-NA (no aneurysm)]. To push the aneurysm phenotype, we also included MU mice with reduced levels of lysyl oxidase [Fbln4E57K/E57K;Lox+/-, referred to as MU-XA (extreme aneurysm)] and compared all groups to wild-type (WT) littermates. The phenotype variation allows investigation of how aneurysm severity correlates with mass transport parameters and extracellular matrix organization. We found that MU-NA ascending thoracic aortae have similar hydraulic conductance (Lp) to WT, but 397% higher solute permeability (ω) for 4 kDa FITC-dextran. In contrast, MU-A and MU-XA ascending thoracic aortae have 44-68% lower Lp and similar ω to WT. The results suggest that ascending thoracic aortic aneurysm progression involves an initial increase in ω, followed by a decrease in Lp after the aneurysm has formed. All MU ascending thoracic aortae are longer and have increased elastic fiber fragmentation in the extracellular matrix. There is a negative correlation between diameter and Lp or ω in MU ascending thoracic aortae. Changes in mass transport due to elastic fiber fragmentation could contribute to aneurysm progression or be leveraged for treatment.NEW & NOTEWORTHY Transmural mass transport is quantified in the ascending thoracic aorta of mice with a mutation in fibulin-4 that is associated with thoracic aortic aneurysms. Fluid and solute transport depend on aneurysm severity, correlate with elastic fiber fragmentation, and may be affected by proteoglycan deposition. Transport properties of the ascending thoracic aorta are provided and can be used in computational models. The changes in mass transport may contribute to aneurysm progression or be leveraged for aneurysm treatment.

Pathophysiology, cellular and molecular mechanisms of large and small vessel diseases

Cerebrovascular disease (CVD) is the second most common cause of cognitive impairment and dementia in aged population. CVD presents in a myriad number of clinical ways based on the functional location of pathology. While primary clinical emphasis has been placed on motor, speech and visual deficits, vascular cognitive decline is a vastly under recognized and devastating condition afflicting millions of Americans. CVD, a disease of the blood vessels that supply blood to brain involves an integration between small and large vessels. Cerebral large vessel diseases (LVD) are associated with atherosclerosis, artery-to-artery embolism, intracardiac embolism and a large vessel stroke leading to substantial functional disability. Cerebral small vessel disease (SVD) is critically involved in stroke, brain hemorrhages, cognitive decline and functional loss in elderly patients. An evolving understanding of cellular and molecular mechanisms emphasizes that inflammatory vascular changes contribute to systemic pathologic conditions of the central nervous systems (CNS), with specific clinical presentations including, cognitive decline. Advances in an understanding of pathophysiology of disease processes and therapeutic interventions may help improve outcomes. This review will focus on large and small vessels diseases and their relationship to vascular cognitive decline, atherosclerosis, stroke, and inflammatory neurodegeneration. We will also emphasize the molecular and cellular mechanisms, as well as genetic and epigenetic factors associated with LVD and SVD.

Macrophage elastase derived from adventitial macrophages modulates aortic remodeling

Abdominal aortic aneurysm (AAA) is pathologically characterized by intimal atherosclerosis, disruption and attenuation of the elastic media, and adventitial inflammatory infiltrates. Although all these pathological events are possibly involved in the pathogenesis of AAA, the functional roles contributed by adventitial inflammatory macrophages have not been fully documented. Recent studies have revealed that increased expression of matrix metalloproteinase-12 (MMP-12) derived from macrophages may be particularly important in the pathogenesis of both atherosclerosis and AAA. In the current study, we developed a carrageenan-induced abdominal aortic adventitial inflammatory model in hypercholesterolemic rabbits and evaluated the effect of adventitial macrophage accumulation on the aortic remodeling with special reference to the influence of increased expression of MMP-12. To accomplish this, we compared the carrageenan-induced aortic lesions of transgenic (Tg) rabbits that expressed high levels of MMP-12 in the macrophage lineage to those of non-Tg rabbits. We found that the aortic medial and adventitial lesions of Tg rabbits were greater in degree than those of non-Tg rabbits, with the increased infiltration of macrophages and prominent destruction of elastic lamellae accompanied by the frequent appearance of dilated lesions, while the intimal lesions were slightly increased. Enhanced aortic lesions in Tg rabbits were focally associated with increased dilation of the aortic lumens. RT-PCR and Western blotting revealed high levels of MMP-12 in the lesions of Tg rabbits that were accompanied by elevated levels of MMP-2 and -3, which was caused by increased number of macrophages. Our results suggest that adventitial inflammation constitutes a major stimulus to aortic remodeling and increased expression of MMP-12 secreted from adventitial macrophages plays an important role in the pathogenesis of vascular diseases such as AAA.

Identification of biomarkers and analysis of infiltrated immune cells in stable and ruptured abdominal aortic aneurysms

Objectives

The mortality rate of abdominal aortic aneurysm (AAA) is extremely high in the older population. This study aimed to identify potential biomarkers of AAA and aortic rupture and analyze infiltration of immune cells in stable and ruptured AAA samples.

Methods

Raw data of GSE47472, GSE57691, and GSE98278 were downloaded. After data processing, the co-expression gene networks were constructed. Gene Ontology and pathway enrichment analysis of AAA- and aortic rupture-related gene modules were conducted using the Database for Annotation, Visualization, and Integrated Discovery. Gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) were used for further enrichment analysis. The CIBERSORT tool was used to analyze the relative abundance of immune cells in samples. Differentially expressed immune-related genes were analyzed between different samples. Predictive models were constructed via extreme gradient boosting, and hub genes were identified according to feature importance.

Results

Blue and yellow modules were significantly related to AAA, and genes in these modules were associated with the aortic wall and immune response, respectively. In terms of aortic rupture, the most relevant module was significantly enriched in the inflammatory response. The results of GSEA and GSVA suggested that immune cells and the inflammatory response were involved in the development of AAA and aortic rupture. There were significant differences in the infiltration of immune cells and expression levels of immune-related genes among different samples. NFKB1 might be an important transcription factor mediating the inflammatory response of AAA and aortic rupture. After the construction of a predictive model, CD19, SELL, and CCR7 were selected as hub genes for AAA whereas OAS3, IFIT1, and IFI44L were identified as hub genes for aortic rupture.

Conclusion

Weakening of the aortic wall and the immune response both contributed to the development of AAA, and the inflammatory response was closely associated with aortic rupture. The infiltration of immune cells was significantly different between different samples. NFKB1 might be an important transcription factor in AAA and aortic rupture. CD19, SELL, and CCR7 had potential diagnostic value for AAA. OAS3, IFIT1, and IFI44L might be predictive factors for aortic rupture.

Rosmarinic Acid Suppresses Abdominal Aortic Aneurysm Progression in Apolipoprotein E-deficient Mice

An abdominal aortic aneurysm is a life-threatening cardiovascular disorder caused by dissection and rupture. No effective medicine is currently available for the > 90% of patients whose aneurysms are below the surgical threshold. The present study investigated the impact of rosmarinic acid, salvianolic acid C, or salvianolic acid B on experimental abdominal aortic aneurysms. Abdominal aortic aneurysms were induced in apolipoprotein E-deficient mice via infusion of angiotensin II for 4 wks. Rosmarinic acid, salvianolic acid C, salvianolic acid B, or doxycycline as a positive control was provided daily through intraperitoneal injection. Administration of rosmarinic acid was found to decrease the thickness of the aortic wall, as determined by histopathological assay. Rosmarinic acid also exhibited protection against elastin fragmentation in aortic media and down-regulated cell apoptosis and proliferation in the aortic adventitia. Infiltration of macrophages, T lymphocytes, and neutrophils in aortic aneurysms was found, especially at the aortic adventitia. Rosmarinic acid, salvianolic acid C, or salvianolic acid B inhibited the infiltration on macrophages specifically, but these compounds did not influence T lymphocytes and neutrophils. Expression of matrix metalloproteinase 9 and macrophage migration inhibitory factor significantly increased in aortic aneurysms. Rosmarinic acid and salvianolic acid C decreased the expression of matrix metalloproteinase-9 in media, and rosmarinic acid also tended to reduce migration inhibitory factor expression. Further then, partial least squares-discriminate analysis was used to classify metabolic changes among different treatments. Rosmarinic acid affected most of the metabolites in the biosynthesis of the citrate cycle, fatty acid pathway significantly. Our present study on mice demonstrated that rosmarinic acid inhibited multiple pathological processes, which were the key features important in abdominal aortic aneurysm formation. Further study on rosmarinic acid, the novel candidate for aneurysmal therapy, should be undertaken to determine its potential for clinical use.

Hutchinson-Gilford Progeria Syndrome: A Literature Review

Hutchinson-Gilford progeria syndrome (HGPS) is a premature aging condition that involves genetic mutations, resulting in debilitating phenotypic features. The present state of knowledge on the molecular pathways that contribute to the pathophysiology of HGPS and the techniques being tested in vitro and in vivo to combat progerin toxicity have been discussed here. Nuclear morphological abnormalities, dysregulated gene expression, DNA repair deficiencies, telomere shortening, and genomic instability are all caused by progerin accumulation, all of which impair cellular proliferative capability. In addition, HGPS cells and preclinical animal models have revealed new information about the disease's molecular and cellular pathways and putative mechanisms involved in normal aging. This article has discussed the understanding of the molecular pathways by which progerin expression leads to HGPS and how the advanced therapy options for HGPS patients can help us understand and treat the condition.

Conductance Artery Wall Layers and Their Respective Roles in the Clearance Functions

Evolutionary organization of the arterial wall into layers occurred concomitantly with the emergence of a highly muscularized, pressurized arterial system that facilitates outward hydraulic conductance and mass transport of soluble substances across the arterial wall. Although colliding circulating cells disperse potential energy within the arterial wall, the different layers counteract this effect: (1) the endothelium ensures a partial barrier function; (2) the media comprises smooth muscle cells capable of endocytosis/phagocytosis; (3) the outer adventitia and perivascular adipocytic tissue are the final receptacles of convected substances. While the endothelium forms a physical and a biochemical barrier, the medial layer is avascular, relying on the specific permeability properties of the endothelium for metabolic support. Different components of the media interact with convected molecules: medial smooth muscle cells take up numerous molecules via scavenger receptors and are capable of phagocytosis of macro/micro particles. The outer layers-the highly microvascularized innervated adventitia and perivascular adipose tissue-are also involved in the clearance functions of the media: the adventitia is the seat of immune response development, inward angiogenesis, macromolecular lymphatic drainage, and neuronal stimulation. Consequently, the clearance functions of the arterial wall are physiologically essential, but also may favor the development of arterial wall pathologies. This review describes how the walls of large conductance arteries have acquired physiological clearance functions, how this is determined by the attributes of the endothelial barrier, governed by endocytic and phagocytic capacities of smooth muscle cells, impacting adventitial functions, and the role of these clearance functions in arterial wall diseases.

Metabolomic Profiling of Angiotensin-II-Induced Abdominal Aortic Aneurysm in Ldlr-/- Mice Points to Alteration of Nitric Oxide, Lipid, and Energy Metabolisms

Aneurysm is the second-most common disease affecting the aorta worldwide after atherosclerosis. While several clinical metabolomic studies have been reported, no study has reported deep metabolomic phenotyping in experimental animal models of aortic aneurysm. We performed a targeted metabolomics study on the blood and aortas of an experimental mice model of aortic aneurysm generated by high-cholesterol diet and angiotensin II in Ldlr^−/− mice. The mice model showed a significant increase in media/lumen ratio and wall area, which is associated with lipid deposition within the adventitia, describing a hypertrophic remodeling with an aneurysm profile of the abdominal aorta. Altered aortas showed increased collagen remodeling, disruption of lipid metabolism, decreased glucose, nitric oxide and lysine metabolisms, and increased polyamines and asymmetric dimethylarginine (ADMA) production. In blood, a major hyperlipidemia was observed with decreased concentrations of glutamine, glycine, taurine, and carnitine, and increased concentrations of the branched amino acids (BCAA). The BCAA/glycine and BCAA/glutamine ratios discriminated with very good sensitivity and specificity between aneurysmatic and non-aneurysmatic mice. To conclude, our results reveal that experimental induction of aortic aneurysms causes a profound alteration in the metabolic profile in aortas and blood, mainly centered on an alteration of NO, lipid, and energetic metabolisms.

Natural Herbal Medicine as a Treatment Strategy for Myocardial Infarction through the Regulation of Angiogenesis

Methods

We conducted a literature search on the bioactive components of medicinal plants and their effects on angiogenesis after MI. We searched for articles in Web of Science, MEDLINE, PubMed, Scopus, Google Scholar, and China National Knowledge Infrastructure databases before April 2021.

Results

In this article, we summarized the mechanisms by which copper ions, microRNA, Akt1, inflammation, oxidative stress, mitochondria, and pericytes are involved in angiogenesis after myocardial infarction. In addition, we reviewed the angiogenic effects of natural herbal medicines such as Salvia miltiorrhiza Bunge Bunge, Carthamus tinctorius L., Pueraria lobata, Astragalus, Panax ginseng C.A. Mey., Panax notoginseng (Burkill) F.H. Chen, Cinnamomum cassia (L.) J. Presl, Rehmannia glutinosa (Gaertn.) DC., Leonurus japonicus Houtt, Scutellaria baicalensis Georgi., and Geum macrophyllum Willd.

Conclusions

Some herbs have the effect of promoting angiogenesis. In the future, natural proangiogenic drugs may become candidates for the treatment of cardiovascular diseases.

Myricetin suppresses the proliferation and migration of vascular smooth muscle cells and inhibits neointimal hyperplasia via suppressing TGFBR1 signaling pathways

BACKGROUND

Neointimal formation, mediated by the proliferation and migration of vascular smooth muscle cells (VSMCs), is a common pathological basis for atherosclerosis and restenosis. Myricetin, a natural flavonoid, reportedly exerts anti-atherosclerotic effects. However, the effect and mechanism of myricetin on VSMCs proliferation and migration and neointimal hyperplasia (NIH) remain unknown.

PURPOSE

We investigated myricetin's effect on NIH, as well as the potential involvement of transforming growth factor-beta receptor 1 (TGFBR1) signaling in mediating myricetin's anti-atherosclerotic and anti-restenotic actions.

METHODS

Myricetin's effects on the proliferation and migration of HASMCs and A7R5 cells were determined by CCK-8, EdU assays, wound healing, Transwell assays, and western blotting (WB).Molecular docking, molecular dynamics (MD) simulation, surface plasmon resonance (SPR) and TGFBR1 kinase activity assays were employed to investigate the interaction between myricetin and TGFBR1. An adenovirus vector encoding TGFBR1 was used to verify the effects of myricetin. In vivo, the left common carotid artery (LCCA) ligation mouse model was adopted to determine the impacts of myricetin on neointimal formation and TGFBR1 activation.

RESULTS

Myricetin dose-dependently inhibited the migration and proliferation in VSMCs, suppressed the expression of CDK4, cyclin D3, MMP2, and MMP9. Molecular docking revealed that myricetin binds to key regions for TGFBR1 antagonist binding, and the binding energy was -9.61 kcal/mol. MD simulation indicated stable binding between TGFBR1 and myricetin. Additionally, SPR revealed an equilibrium dissociation constant of 4.35 × 10^-5 M between myricetin and TGFBR1. According to the TGFBR1 kinase activity assay, myricetin directly inhibited TGFBR1 kinase activity (IC₅₀ = 8.551 μM). Furthermore, myricetin suppressed the phosphorylation level of TGFBR1, Smad2, and Smad3 in a dose-dependent pattern, which was partially inhibited by TGFBR1 overexpression. Consistently, TGFBR1 overexpression partially rescued the suppressive roles of myricetin on VSMCs migration and proliferation. Moreover, myricetin dramatically inhibited NIH and reduced TGFBR1, Smad2, and Smad3 phosphorylation in the LCCA.

CONCLUSION

This is the first study to demonstrate that myricetin suppresses NIH and VSMC proliferation and migration via inhibiting TGFBR1 signaling. Myricetin can be developed as a potential therapeutic candidate for treating atherosclerosis and vascular restenosis.

The Prevalence of Concomitant Abdominal Aortic Aneurysm and Cancer

Cancers and abdominal aortic aneurysms (AAA) cause substantial morbidity and mortality and commonly develop in old age. It has been previously reported that AAA patients have a high prevalence of cancers, which has raised the question of whether this is a simple collision, association or causation. Clinical trials or observational studies with sufficient power to prove this association between them were limited because of the relatively low frequency and slow disease process of both diseases. We aimed to determine whether there is a significant association between AAA and cancers using nationwide data. The patients aged > 50 years and diagnosed with AAA between 2002 and 2015, patients with heart failure (HF) and controls without an AAA or HF matched by age, sex and cardiovascular risk factors were enrolled from the national sample cohort from the National Health Insurance claims database of South Korea. The primary outcome was the prevalence rate of cancers in the participants with and without an AAA. The secondary outcome was cancer-related survival and cancer risk. Overall, 823 AAA patients (mean (standard deviation) age, 71.8 (9.4) years; 552 (67.1%) men) and matching 823 HF patients and 823 controls were identified. The prevalence of cancers was 45.2% (372/823), 41.7% (343/823) and 35.7% (294/823) in the AAA, HF and control groups, respectively; it was significantly higher in the AAA group than in the control group (p < 0.001). The risk of developing cancer was higher in the AAA patients than in the controls (adjusted odds ratio (OR), 1.52 (95% confidence interval [CI], 1.24-1.86), p < 0.001) and in the HF patients (adjusted OR, 1.37 (1.24-1.86), p = 0.006). The cancer-related death rate was 2.64 times higher (95% CI, 2.22-3.13; p < 0.001) for the AAA patients and 1.63 times higher (95% CI, 1.37-1.92; p < 0.001) for the HF patients than for the controls. The most common causes of death in the AAA patients were cancer and cardiovascular disease. There was a significantly increased risk of cancer in the AAA than in the HF and control groups. Therefore, appropriate screening algorithms might be necessary for earlier detection of both diseases to improve long-term survival.

Principles of Intravascular Lithotripsy for Calcific Plaque Modification

A significant proportion of lesions treated with transcatheter interventions in the coronary and peripheral vascular beds exhibit moderate to severe calcific plaques known to portend lower procedural success rates, increased peri-procedural adverse events, and unfavorable clinical outcomes compared with noncalcific plaques. Adapted from lithotripsy technology used for treatment of ureterorenal calculi, intravascular lithotripsy (IVL) is a novel technique for the treatment of severely calcific plaque lesions that uses acoustic shockwaves in a balloon-based delivery system. Shockwaves induce calcium fractures, which facilitate stent expansion and luminal gain. In this review, the authors summarize the physics, preclinical and clinical data on IVL use in the coronary and peripheral vasculature, and future directions of IVL in transcatheter cardiovascular therapies.

Adenosine and adenosine receptor-mediated action in coronary microcirculation

Adenosine is an ubiquitous extracellular signaling molecule and plays a fundamental role in the regulation of coronary microcirculation through activation of adenosine receptors (ARs). Adenosine is regulated by various enzymes and nucleoside transporters for its balance between intra- and extracellular compartments. Adenosine-mediated coronary microvascular tone and reactive hyperemia are through receptors mainly involving A_2AR activation on both endothelial and smooth muscle cells, but also involving interaction among other ARs. Activation of ARs further stimulates downstream targets of H₂O₂, K_ATP, K_V and K_Ca2+ channels leading to coronary vasodilation. An altered adenosine-ARs signaling in coronary microcirculation has been observed in several cardiovascular diseases including hypertension, diabetes, atherosclerosis and ischemic heart disease. Adenosine as a metabolite and its receptors have been studied for its both therapeutic and diagnostic abilities. The present review summarizes important aspects of adenosine metabolism and AR-mediated actions in the coronary microcirculation.

Alginate hydrogel polymers enable efficient delivery of a vascular-targeted AAV vector into aortic tissue

Gene therapeutic approaches to aortic diseases require efficient vectors and delivery systems for transduction of endothelial cells (ECs) and smooth muscle cells (SMCs). Here, we developed a novel strategy to efficiently deliver a previously described vascular-specific adeno-associated viral (AAV) vector to the abdominal aorta by application of alginate hydrogels. To efficiently transduce ECs and SMCs, we used AAV9 vectors with a modified capsid (AAV9SLR) encoding enhanced green fluorescent protein (EGFP), as wild-type AAV vectors do not transduce ECs and SMCs well. AAV9SLR vectors were embedded into a solution containing sodium alginate and polymerized into hydrogels. Gels were surgically implanted around the adventitia of the infrarenal abdominal aorta of adult mice. Three weeks after surgery, an almost complete transduction of both the endothelium and tunica media adjacent to the gel was demonstrated in tissue sections. Hydrogel-mediated delivery resulted in induction of neutralizing antibodies but did not cause inflammatory responses in serum or the aortic wall. To further determine the translational potential, aortic tissue from patients was embedded ex vivo into AAV9SLR-containing hydrogel, and efficient transduction could be confirmed. These findings demonstrate that alginate hydrogel harboring a vascular-targeting AAV9SLR vector allows efficient local transduction of the aortic wall.

Rapid Rise of Cardio-Ankle Vascular Index May Be a Trigger of Cerebro-Cardiovascular Events: Proposal of Smooth Muscle Cell Contraction Theory for Plaque Rupture

Cardiovascular diseases have been recognized as the main cause of death all over the world. Recently, the established cardio-ankle vascular index (CAVI) has become known as an index of arterial stiffness of the arterial tree from the origin of the aorta to the ankle. CAVI reflects the progress of arteriosclerosis, and a rapid rise in CAVI indicates arterial smooth muscle cell contraction. Considering the vasculature of the atheroma where vasa vasorum penetrates the smooth muscle cell layer and supplies blood to the intimal atheromatous lesion, a rapid rise of CAVI means "choked" atheroma. Thus, we proposed a "smooth muscle cell contraction" hypothesis of plaque rupture.

Insights on the Pathogenesis of Aneurysm through the Study of Hereditary Aortopathies

Thoracic aortic aneurysms (TAA) are permanent and localized dilations of the aorta that predispose patients to a life-threatening risk of aortic dissection or rupture. The identification of pathogenic variants that cause hereditary forms of TAA has delineated fundamental molecular processes required to maintain aortic homeostasis. Vascular smooth muscle cells (VSMCs) elaborate and remodel the extracellular matrix (ECM) in response to mechanical and biochemical cues from their environment. Causal variants for hereditary forms of aneurysm compromise the function of gene products involved in the transmission or interpretation of these signals, initiating processes that eventually lead to degeneration and mechanical failure of the vessel. These include mutations that interfere with transduction of stimuli from the matrix to the actin-myosin cytoskeleton through integrins, and those that impair signaling pathways activated by transforming growth factor-β (TGF-β). In this review, we summarize the features of the healthy aortic wall, the major pathways involved in the modulation of VSMC phenotypes, and the basic molecular functions impaired by TAA-associated mutations. We also discuss how the heterogeneity and balance of adaptive and maladaptive responses to the initial genetic insult might contribute to disease.

Complement C5 Protein as a Marker of Subclinical Atherosclerosis

BACKGROUND

The mechanisms underlying early atherosclerotic plaque formation are not completely understood. Moreover, plasma biomarkers of subclinical atherosclerosis are lacking.

OBJECTIVES

The purpose of this study was to analyze the temporal and topologically resolved protein changes taking place in human aortas with early atherosclerosis to find new potential diagnostic and/or therapeutic targets.

METHODS

The protein composition of healthy aortas (media layer) or with early atheroma (fatty streak and fibrolipidic, media and intima layers) was analyzed by deep quantitative multiplexed proteomics. Further analysis was performed by Western blot, immunohistochemistry, real-time polymerase chain reaction, and enzyme-linked immunosorbent assay. Plasma levels of complement C5 were analyzed in relation to the presence of generalized (>2 plaques) or incipient (0 to 2 plaques) subclinical atherosclerosis in 2 independent clinical cohorts (PESA [Progression of Early Subclinical Atherosclerosis] [n = 360] and NEFRONA [National Observatory of Atherosclerosis in Nephrology] [n = 394]).

RESULTS

Proteins involved in lipid transport, complement system, immunoglobulin superfamily, and hemostasis are increased in early plaques. Components from the complement activation pathway were predominantly increased in the intima of fibrolipidic plaques. Among them, increased C5 protein levels were further confirmed by Western blot, enzyme-linked immunosorbent assay and immunohistochemistry, and associated with in situ complement activation. Plasma C5 was significantly increased in individuals with generalized subclinical atherosclerosis in both PESA and NEFRONA cohorts, independently of risk factors. Moreover, in the PESA study, C5 plasma levels positively correlated with global plaque volume and coronary calcification.

CONCLUSIONS

Activation of the complement system is a major alteration in early atherosclerotic plaques and is reflected by increased C5 plasma levels, which have promising value as a novel circulating biomarker of subclinical atherosclerosis.

Periadventitial Delivery of Simvastatin-Loaded Microparticles Attenuate Venous Neointimal Hyperplasia Associated With Arteriovenous Fistula

Background

Venous neointimal hyperplasia and venous stenosis (VS) formation can result in a decrease in arteriovenous fistula (AVF) patency in patients with end‐stage renal disease. There are limited therapies that prevent VNH/VS. Systemic delivery of simvastatin has been shown to reduce VNH/VS but local delivery may help decrease the side effects associated with statin use. We determined if microparticles (MP) composed of cyclodextrins loaded with simvastatin (MP‐SV) could reduce VS/VNH using a murine arteriovenous fistula model with chronic kidney disease.

Methods and Results

Male C57BL/6J mice underwent nephrectomy to induce chronic kidney disease. Four weeks later, an arteriovenous fistula was placed and animals were randomized to 3 groups: 20 μL of PBS or 20 μL of PBS with 16.6 mg/mL of either MP or MP‐SV. Animals were euthanized 3 days later and the outflow veins were harvested for quantitative reverse transcriptase–polymerase chain reaction analysis and 28 days later for immunohistochemistical staining with morphometric analysis. Doppler ultrasound was performed weekly. Gene expression of vascular endothelial growth factor‐A (Vegf‐A), matrix metalloproteinase‐9 (Mmp‐9), transforming growth factor beta 1 (Tgf‐β1), and monocyte chemoattractant protein‐1 (Mcp‐1) were significantly decreased in MP‐SV treated vessels compared with controls. There was a significant decrease in the neointimal area, cell proliferation, inflammation, and fibrosis, with an increase in apoptosis and peak velocity in MP‐SV treated outflow veins. MP‐SV treated fibroblasts when exposed to hypoxic injury had decreased gene expression of Vegf‐A and Mmp‐9.

Conclusions

In experimental arteriovenous fistulas, periadventitial delivery of MP‐SV decreased gene expression of Vegf‐A, Mmp‐9, Tgf‐β1 and Mcp‐1, VNH/VS, inflammation, and fibrosis.

[William Harvey reinterpreted in the light of species evolution (II) - Physiological and pathological consequences of the evolution of circulation]

In the first part of this review [22], "How and why circulatory phylogenesis fits into the evolution of species", we explained that the acquisition of a high-pressure arterial sector, as originally described by William Harvey in 1619, was the consequence, during evolution, of the appearance of vasomotor tone, inducing systemic friction forces (peripheral resistances), which, regulated locally (by vasodilatation), allows to adapt metabolic needs to the demand of functionally active territories. In this second part, we will try to understand how this phylogenesis directly influences the physiology, then the pathologies of the circulatory system in humans which are largely predominant, but not exclusively.

William Harvey réinterprété à la lumière de l’évolution des espèces (I)

Au commencement est la pompe cardiaque qui produit un flux sanguin cyclique (énergie cinétique, Ek). En 1619, William Harvey (1578-1657) décrit expérimentalement, en utilisant des garrots veineux ou artériels, l’anatomie fonctionnelle de la circulation sanguine chez l’homme, à l’exception de la circulation capillaire. Pour la première fois est décrite la circulation sanguine en deux circuits fermés parallèles, l’un à haute pression, l’autre à basse pression. Marcello Malpighi (1628-1694) la complète par l’observation en microscopie du réseau capillaire. Un siècle plus tard, apparaissent les premières hypothèses sur l’évolution des espèces. Jean-Baptiste Lamarck (1744-1829) propose en 1809 une théorie de transmission évolutive des caractères phénotypiques par adaptation aux contraintes environnementales. En 1859, Charles Darwin (1809-1882) élabore une théorie de la sélection naturelle. L’interprétation qui prévaut actuellement intègre à la fois la génétique et l’épigénétique dans la transmission intergénérationnelle, et dans la dynamique de développement des caractères phénotypiques individuels, en particulier chez l’homme.

Regulatory Roles of Related Long Non-coding RNAs in the Process of Atherosclerosis

Atherosclerosis (AS) is the main cause of coronary heart disease, cerebral infarction, and peripheral vascular disease, which comprise serious hazards to human health. Atherosclerosis is characterized by the deposition of lipids on the interior walls of blood vessels, causing an inflammatory response of immune cells, endothelial cells, and smooth muscle cells, and a proliferation cascade reaction. Despite years of research, the underlying pathogenesis of AS is not fully defined. Recent advances in our understanding of the molecular mechanisms by which non-coding RNA influences the initiation and progression of AS have shown that long non-coding RNAs (lncRNAs) regulate important stages in the atherosclerotic process. In this review, we summarize current knowledge of lncRNAs, which influence the development of AS. We review the regulatory processes of lncRNAs on core stages of atherosclerotic progression, including lipid metabolism, inflammation, vascular cell proliferation, apoptosis, adhesion and migration, and angiogenesis. A growing body of evidence suggests that lncRNAs have great potential as new therapeutic targets for the treatment of vascular diseases.

Aortic adventitial thickness as a marker of aortic atherosclerosis, vascular stiffness, and vessel remodeling in systemic lupus erythematosus

INTRODUCTION

There is limited human imaging data on the association of adventitial thickness (AT) with arterial disease. Systemic lupus erythematosus (SLE) is a prototypical disease model for studying markers of premature arterial disease.

OBJECTIVE

To determine if increased aortic AT is associated with aortic atherosclerosis [increased intima media thickness (IMT) or plaques], stiffness [increased pressure-strain elastic modulus (PSEM)], and vessel remodeling.

METHODS

In total, 70 SLE patients and 26 age- and sex-matched controls underwent transesophageal echocardiography (TEE). Two-dimensional guided M-mode images were obtained to assess AT, IMT, and plaques, and PSEM at the proximal, mid, and distal thoracic aorta. Images were interpreted by 3 observers unaware of the subjects' clinical data and each other's measurements. Abnormal aortic AT, IMT, and PSEM were defined as > 2SD above the overall mean values in controls and corresponded to > 1 mm, > 1 mm, and > 10.6 Pascal units, respectively. Plaques were defined as focal-protruding IMT > 50% of the surrounding vessel wall.

RESULTS

Abnormal aortic AT, atherosclerosis, and abnormal stiffness were more frequent in SLE patients than in controls (all p ≤ 0.02). In SLE patients, abnormal AT combined with atherosclerosis was associated with larger aortic end-diastolic diameters than in controls (p ≤ 0.05). In SLE patients, aortic AT was greater in patients with atherosclerosis and in those with abnormal stiffness than in patients without these abnormalities (all p ≤ 0.02). In patients with abnormal AT, the degree of aortic stiffness was similar to those with atherosclerosis (p = 0.22).

CONCLUSION

In patients with SLE, increased aortic AT is associated with aortic atherosclerosis, abnormal stiffness, and eccentric vessel remodeling. Key Points • In patients with SLE, abnormal aortic adventitial thickness is associated with aortic atherosclerosis, abnormal stiffness, and eccentric vessel remodeling. • In patients with SLE, aortic adventitial thickening may contribute to the extent of aortic atherosclerosis, abnormal aortic stiffness, and vessel remodeling. • To our knowledge, this is the first human imaging study to characterize the aortic adventitial layer and delineate its association with aortic disease.

Phylogenic Determinants of Cardiovascular Frailty, Focus on Hemodynamics and Arterial Smooth Muscle Cells

The evolution of the circulatory system from invertebrates to mammals has involved the passage from an open system to a closed in-parallel system via a closed in-series system, accompanying the increasing complexity and efficiency of life’s biological functions. The archaic heart enables pulsatile motion waves of hemolymph in invertebrates, and the in-series circulation in fish occurs with only an endothelium, whereas mural smooth muscle cells appear later. The present review focuses on evolution of the circulatory system. In particular, we address how and why this evolution took place from a closed, flowing, longitudinal conductance at low pressure to a flowing, highly pressurized and bifurcating arterial compartment. However, although arterial pressure was the latest acquired hemodynamic variable, the general teleonomy of the evolution of species is the differentiation of individual organ function, supported by specific fueling allowing and favoring partial metabolic autonomy. This was achieved via the establishment of an active contractile tone in resistance arteries, which permitted the regulation of blood supply to specific organ activities via its localized function-dependent inhibition (active vasodilation). The global resistance to viscous blood flow is the peripheral increase in frictional forces caused by the tonic change in arterial and arteriolar radius, which backscatter as systemic arterial blood pressure. Consequently, the arterial pressure gradient from circulating blood to the adventitial interstitium generates the unidirectional outward radial advective conductance of plasma solutes across the wall of conductance arteries. This hemodynamic evolution was accompanied by important changes in arterial wall structure, supported by smooth muscle cell functional plasticity, including contractility, matrix synthesis and proliferation, endocytosis and phagocytosis, etc. These adaptive phenotypic shifts are due to epigenetic regulation, mainly related to mechanotransduction. These paradigms actively participate in cardio-arterial pathologies such as atheroma, valve disease, heart failure, aneurysms, hypertension, and physiological aging.

Ectopic Lymphoid Organs and Immune-Mediated Diseases: Molecular Basis for Pharmacological Approaches

Chronic inflammation is the result a persistent increase in the expression of several proinflammatory pathways with impaired inflammatory resolution. Ectopic lymphoid organs (ELOs), untypical lymphoid annexes, emerge during chronic inflammation and contribute to the physiopathology of chronic inflammatory disorders. This review discusses the pathophysiological role of ELOs in the progression of immune-mediated inflammatory diseases (IMIDs), including multiple sclerosis (MS), rheumatoid arthritis (RA), inflammatory bowel disease (IBD), atherosclerosis, and Sjögren syndrome (SSj). The molecular pathways underlying the emergence of ELOs are of interest for the development of novel pharmacological approaches for the management of chronic inflammatory diseases.

Persistence of Intraluminal Thrombus Makes Saccular Aneurysm More Biologically Active than Fusiform in an Experimental Rat Model

INTRODUCTION

Saccular aneurysms are thought to have a worse prognosis than fusiform aneurysms in humans, due to hemodynamic reasons. However, data comparing hemodynamic and biology in saccular and fusiform aneurysms are lacking. The main objective was to evaluate the impact of aneurysm morphology on intra-luminal thrombus (ILT) formation and activity.

METHODS

Forty Lewis rats were ran-domly divided into 2 groups of 20: "saccular" (Group A) and "fusiform" (Group B) aneurysms. Decellularized thoracic aortas from guinea pigs were xenografted to create saccular or fusiform aneurysms. Final imaging evaluation of the aneurysms was carried out during the third week, by quantitative Doppler ultrasound and magnetic resonance imaging. Assays of myeloperoxidase (MPO), platelet factor 4 (PF4), advanced oxidation protein products (AOPPs) iron and matrix metallopeptidase-9 (MMP-9) were performed as biological criteria.

RESULTS

Quantitatively, saccular aneurysms are characterized by a more thicker ILT, lower inflow velocities and more important relative backflow velocities as compared to fusiform aneurysms. Compared to fusiform, saccular aneurysms released significantly more MPO (p = 0.004), PF4 (p = 0.02), AOPPs (p < 0.002), iron (p < 0.0001) and MMP-9 (p < 0.04).

CONCLUSION

Experimental saccular and fusiform aneurysms show differential specific hemodynamics, which seem to impact the histology and the biology of the ILT in each type of aneurysm.

Circular RNA ciRS-7 promotes tube formation in microvascular endothelial cells through downregulation of miR-26a-5p

Atherosclerosis is one of the most common and crucial heart diseases involving the heart and brain. At present, atherosclerosis and its major complications comprise the leading causes of death worldwide. Our purpose was to identify the role of ciRS-7 in atherosclerosis. Tubulogenesis of HMEC-1 cell was evaluated utilizing tube formation assay. Cell Counting Kit-8 assay and flow cytometry were utilized to test viability and apoptosis. Migration assay was utilized to determine the migration capacity of experimental cells. Western blot was applied to examine apoptosis and tube formation-associated protein expression. In addition, the above experiments were repeated when silencing ciRS-7, overexpressing ciRS-7, and upregulating miR-26a-5p. HMEC-1 cells formed tube-like structures over time. Silencing ciRS-7 suppressed viability, migration, and tube formation but promoted apoptosis. Oppositely, overexpressing ciRS-7 reversed the effect in HMEC-1 cells. miR-26a-5p expression was elevated by silencing ciRS-7 and reduced by overexpressing ciRS-7. Moreover, overexpressing ciRS-7 facilitated viability, migration, and tube formation via upregulating miR-26a-5p. Conclusively, overexpressing ciRS-7 mobilized phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) pathway and suppressed c-Jun N-terminal kinase (JNK)/p38 pathway. ciRS-7 exerted influence on apoptosis, viability, migration, and tube formation through mediating PI3K/AKT and JNK/p38 pathways by miR-26a-5p downregulation in HMEC-1 cells.

Carotid Extra-Media Thickness in Children: Relationships With Cardiometabolic Risk Factors and Endothelial Function

Background: Emerging evidence suggests that structural adventitial modifications and perivascular adipose tissue (PAT) may have a role in early atherogenesis. In a cohort of children and adolescents, we explored (1) the association of carotid extra-media thickness (cEMT), an ultrasound measure whose main determinants are arterial adventitia and PAT, with obesity and its cardiometabolic complications; and (2) the interplay between cEMT and endothelial function. Methods: The study participants included 286 youths (age, 6-16 years; 154 boys, and 132 girls). Anthropometric and laboratory parameters, liver ultrasound, vascular structure measures [cEMT and carotid intima-media thickness (cIMT)], endothelial function [brachial artery flow-mediated dilation (FMD)] were obtained in all subjects. Non-alcoholic fatty liver disease (NAFLD) was diagnosed in the presence of hepatic fat on ultrasonography, in the absence of other causes of liver disease. Diagnosis of metabolic syndrome (MetS) was established on the basis of three or more of the following cardiovascular disease (CVD) risk variables: abdominal obesity, high triglycerides, low high-density lipoprotein cholesterol, elevated blood pressure (BP), and impaired fasting glucose. Results: cEMT demonstrated significant associations with body-mass index (BMI) and waist circumference (WC), BP, insulin resistance, NAFLD, and inflammation. No association was found between cEMT and lipid values, and between cEMT and MetS. A stepwise multivariate linear regression analysis indicated that WC (β coefficient, 0.35; P < 0.0001) was the only determinant of cEMT, independently of other major cardiometabolic risk factors. Further adjustment for cIMT did not significantly alter this association. FMD was correlated to age, Tanner stage, total and abdominal obesity, BP, NAFLD, and cEMT. The association between FMD and cEMT was independent of age, sex, Tanner stage, WC, and BMI (β coefficient, -0.14; P = 0.027). After controlling for CVD risk factors and basal brachial artery diameter, cEMT remained associated with FMD (β coefficient, -0.11; P = 0.049). Conclusions: In youths, cEMT is associated with abdominal fat, a well-established body fat depot with important implications for cardiovascular diseases. Furthermore, cEMT is related to FMD, suggesting that arterial adventitia and PAT may be involved in the early changes in endothelial function.

From genetics to response to injury: vascular smooth muscle cells in aneurysms and dissections of the ascending aorta

Vascular smooth muscle cells (vSMCs) play a crucial role in both the pathogenesis of Aneurysms and Dissections of the ascending thoracic aorta (TAAD) in humans and in the associated adaptive compensatory responses, since thrombosis and inflammatory processes are absent in the majority of cases. Aneurysms and dissections share numerous characteristics, including aetiologies and histopathological alterations: vSMC disappearance, medial areas of mucoid degeneration, and extracellular matrix (ECM) breakdown. Three aetiologies predominate in TAAD in humans: (i) genetic causes in heritable familial forms, (ii) an association with bicuspid aortic valves, and (iii) a sporadic degenerative form linked to the aortic aging process. Genetic forms include mutations in vSMC genes encoding for molecules of the ECM or the TGF-β pathways, or participating in vSMC tone. On the other hand, aneurysms and dissections, whatever their aetiologies, are characterized by an increase in wall permeability leading to transmural advection of plasma proteins which could interact with vSMCs and ECM components. In this context, blood-borne plasminogen appears to play an important role, because its outward convection through the wall is increased in TAAD, and it could be converted to active plasmin at the vSMC membrane. Active plasmin can induce vSMC disappearance, proteolysis of adhesive proteins, activation of MMPs and release of TGF-β from its ECM storage sites. Conversely, vSMCs could respond to aneurysmal biomechanical and proteolytic injury by an epigenetic phenotypic switch, including constitutional overexpression and nuclear translocation of Smad2 and an increase in antiprotease and ECM protein synthesis. In contrast, such an epigenetic phenomenon is not observed in dissections. In this context, dysfunction of proteins involved in vSMC tone are interesting to study, particularly in interaction with plasma protein transport through the wall and TGF-β activation, to establish the relationship between these dysfunctions and ECM proteolysis.

Coronary Artery Remodeling and Fibrosis With Continuous-Flow Left Ventricular Assist Device Support

BACKGROUND

Coronary artery fluid dynamics may be altered because of the nonphysiological flow seen in continuous-flow left ventricular assist devices (CF-LVADs). Our aim was to study the structure and composition of coronary vessels after CF-LVAD.

METHODS AND RESULTS

Coronary arteries were collected from patients with heart failure (HF) at the time of transplantation, of whom 15 were supported with a CF-LVAD before transplant (HF+LVAD group) and 9 were not (HF non-LVAD group). In addition, coronary samples were obtained from 5 nonfailing age-matched donors (nonfailing group). Histological analysis was performed to quantify coronary morphology, composition, vascular fibrosis, and vasa vasorum density. The age and sex mix of the 3 groups were similar, and the mean duration of LVAD support was 213 days. Compared with patients with HF and nonfailing donors, the arteries from patients with HF+LVAD had expansion of the adventitia, breakdown of the internal elastic lamina, and increased adventitial collagen deposition and density of vasa vasorum.

CONCLUSIONS

Among patients supported with CF-LVADs, the coronary arteries develop marked remodeling with increased adventitial fibrosis. The physiological consequences of these structural changes are unknown, but it is possible that arterial contractility may be impaired, thus limiting coronary flow reserve and promoting myocardial ischemia. This may contribute to CF-LVAD complications, such as ventricular arrhythmias and right ventricular failure. As more patients receive CF-LVADs and new pump technology attempts to modulate flow profiles and pulsatility, further research is needed to understand the mechanisms and long-term sequela of these changes in coronary arteries and other vascular beds.

Adventitial fibroblast-derived vascular endothelial growth factor promotes vasa vasorum-associated neointima formation and macrophage recruitment

Aims

Adventitial vasa vasorum provides oxygen and nourishment to the vascular wall, but whether it regulates vascular disease remains unclear. We have previously shown that an increased expression of VEGF (vascular endothelial growth factor) is associated with macrophage infiltration. This study aims to determine whether adventitial fibroblast (AF)-derived VEGF increases the number of vasa vasorum contributing to neointima formation through macrophage recruitment.

Methods and results

In rat balloon injury model, vasa vasorum count was increased particularly in the adventitia accompanied by cell proliferation and VEGF expression. Both endogenous and PKH26-labelled exogenous macrophages were mainly distributed in adventitia around vasa vasorum. Interestingly, perivascular delivery of Ranibizumab preferentially concentrated in adventitia resulted in a decrease of neointima formation with concurrent reduction of vasa vasorum count and macrophage infiltration. AFs with adenovirus-mediated VEGF over-expression delivered to the adventitia significantly enhanced these pathological changes after injury. In Tie2-cre/Rosa-LoxP-RFP mice, endothelial cells were increased in the adventitia after wire injury. By using multiphoton laser scanning microscopy, macrophage rolling, adhesion and transmigration were observed in vasa vasorum. Moreover, adoptive transfer of macrophages accelerated injury-induced neointima formation. VEGF-neutralizing antibody administration also attenuated wire injury-induced neointima formation and macrophage infiltration. In primary cultured AFs, exogenous VEGF increased VEGF expression and secretion in a time- and dose-dependent manner. AF-conditioned medium promoted endothelial cell angiogenesis, vascular cell adhesion molecule-1 expression and macrophage adhesion was blocked by VEGF-neutralizing antibody and VEGFR2 inhibitor ZM323881, which also inhibited activation of VEGFR2/ERK1/2 pathway.

Conclusion

These results demonstrate that AF-derived VEGF plays a significant role in the increase of vasa vasorum count which is involved in macrophage recruitment and neointima formation.

Antithrombotic therapy in abdominal aortic aneurysm: beneficial or detrimental?

Abdominal aortic aneurysm (AAA) is a degenerative vascular pathology resulting in significant morbidity and mortality in older adults due to rupture and sudden death. Despite 150 000 new cases and nearly 15 000 deaths annually, the only approved treatment of AAA is surgical or endovascular intervention when the risk for aortic rupture is increased. The goal of the scientific community is to develop novel pharmaceutical treatment strategies to reduce the need for surgical intervention. Because most clinically relevant AAAs contain a complex structure of fibrin, inflammatory cells, platelets, and red blood cells in the aneurysmal sac known as an intraluminal thrombus (ILT), antithrombotic therapies have emerged as potential pharmaceutical agents for the treatment of AAA progression. However, the efficacy of these treatments has not been shown, and the effects of shrinking the ILT may be as detrimental as they are beneficial. This review discusses the prospect of anticoagulant and antiplatelet (termed collectively as antithrombotic) therapies in AAA. Herein, we discuss the role of the coagulation cascade and platelet activation in human and animal models of AAA, the composition of ILT in AAA, a possible role of the ILT in aneurysm stabilization, and the implications of antithrombotic drugs in AAA treatment.

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.

A chemo-mechano-biological formulation for the effects of biochemical alterations on arterial mechanics: the role of molecular transport and multiscale tissue remodelling

This paper presents a chemo-mechano-biological framework for arterial physiopathology. The model accounts for the fine remodelling in the multiscale hierarchical arrangement of tissue constituents and for the diffusion of molecular species involved in cell-cell signalling pathways. Effects in terms of alterations in arterial compliance are obtained. A simple instructive example is introduced. Although oversimplified with respect to realistic case studies, the proposed application mimics the biochemical activity of matrix metalloproteinases, transforming growth factors beta and interleukins on tissue remodelling. Effects of macrophage infiltration, of intimal thickening and of a healing phase are investigated, highlighting the corresponding influence on arterial compliance. The obtained results show that the present approach is able to capture changes in arterial mechanics as a consequence of the alterations in tissue biochemical environment and cellular activity, as well as to incorporate the protective role of both autoimmune responses and pharmacological treatments.

Case Study: Intra-Patient Heterogeneity of Aneurysmal Tissue Properties

Introduction: Current recommendations for surgical treatment of abdominal aortic aneurysms (AAAs) rely on the assessment of aortic diameter as a marker for risk of rupture. The use of aortic size alone may overlook the role that vessel heterogeneity plays in aneurysmal progression and rupture risk. The aim of the current study was to investigate intra-patient heterogeneity of mechanical and fluid mechanical stresses on the aortic wall and wall tissue histopathology from tissue collected at the time of surgical repair. Methods: Finite element analysis (FEA) and computational fluid dynamics (CFD) simulations were used to predict the mechanical wall stress and the wall shear stress fields for a non-ruptured aneurysm 2 weeks prior to scheduled surgery. During open repair surgery one specimen partitioned into different regions was collected from the patient's diseased aorta according to a pre-operative map. Histological analysis and mechanical testing were performed on the aortic samples and the results were compared with the predicted stresses. Results: The preoperative simulations highlighted the presence of altered local hemodynamics particularly at the proximal segment of the left anterior area of the aneurysm. Results from the post-operative assessment on the surgical samples revealed a considerable heterogeneity throughout the aortic wall. There was a positive correlation between elastin fragmentation and collagen content in the media. The tensile tests demonstrated a good prediction of the locally varying constitutive model properties predicted using geometrical variables, i.e., wall thickness and thrombus thickness. Conclusions: The observed large regional differences highlight the local response of the tissue to both mechanical and biological factors. Aortic size alone appears to be insufficient to characterize the large degree of heterogeneity in the aneurysmal wall. Local assessment of wall vulnerability may provide better risk of rupture predictions.

Left subclavian artery dissection associated with connective tissue abnormalities resembling Marfan-like syndrome in an English bulldog

The unexpected demise of a 12-year-old male neutered English bulldog solicited a gross examination, which revealed a blood-filled space occurring in the proximal left subclavian artery (LSA). It originated about 1 cm from the branching point of the vessel and progressively dilated for 3 cm distal to this origin. Histopathological investigation showed that the tunica media of the LSA was more than 50% split, with the blood-filled space dissecting through the arterial wall. In the tunica media of the LSA, severe multifocal fragmentation and/or loss of the elastic fibers was observed. The retained disorganized elastic fibers were separated and disoriented due to accumulations of acid mucopolysaccharide. Marked, diffuse medial, and adventitial fibrous tissue deposition was also identified. The cause of death was attributed to acute hemorrhagic and necrotizing pancreatitis with pulmonary edema, suggesting that LSA dissection was an incidental finding. Subclavian artery dissection is extremely rare in humans, where the involvement of the LSA in cases of aortic dissection both with or without Marfan syndrome has been reported. Aortic and pulmonary artery dissection in bovines and aortic aneurysm and dissection in dogs have been reported to be associated with Marfan and Marfan-like syndromes, respectively. Histopathological findings suggestive of underlying connective tissue abnormalities resembling Marfan-like syndrome (i.e., the appearance of the elastic tissue and the degenerative changes of the tunica media) were detected in the first case of LSA dissection in dogs and veterinary medicine, herein described.

Adventitial Activation in the Pathogenesis of Injury-Induced Arterial Remodeling: Potential Implications in Transplant Vasculopathy

Transplant vasculopathy is one of the major causes of chronic rejection after solid organ transplantation. The pathogenic mechanisms of transplant vasculopathy are still poorly understood. Herein, we summarize current evidence suggesting that activation of the tunica adventitia may be involved in the pathogenesis of transplant vasculopathy. Adventitia is an early responder to various vascular injuries and plays an integral role in eliciting vascular inflammation and remodeling. Accumulation of macrophages in the adventitia promotes the development of vascular remodeling by releasing a variety of paracrine factors that have profound impacts on vascular mural cells. Targeting adventitial macrophages has been shown to be effective for repressing transplantation-induced arterial remodeling in animal models. Adventitia also fosters angiogenesis, and neovascularization of the adventitial layer may facilitate the transport of inflammatory cells through the arterial wall. Further investigations are warranted to clarify whether inhibiting adventitial oxidative stress and/or adventitial neovascularization are better strategies for preventing transplant vasculopathy.

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.

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.

Clearance of plasmin-PN-1 complexes by vascular smooth muscle cells in human aneurysm of the ascending aorta

Plasminogen is a circulating zymogen which enters the arterial wall by radial, transmural hydraulic conductance, where it is converted to plasmin by tissue plasminogen activator t-PA on an activation platform involving S100A4 on the vascular smooth muscle cell (vSMC) membrane. Plasmin is involved in the progression of human thoracic aneurysm of the ascending aorta (TAA). vSMCs protect the TAA wall from plasmin-induced proteolytic injury by expressing high levels of antiproteases. Protease nexin-1 (PN-1) is a tissue antiprotease belonging to the serpin superfamily, expressed in the vascular wall, and is able to form a covalent complex with plasmin. LDL receptor-related protein-1 (LRP-1) is a scavenger receptor implicated in protease-antiprotease complex internalization. In this study, we investigated whether PN-1 and LRP-1 are involved in the inhibition and clearance of plasminogen by the SMCs of human TAA. We demonstrated an overexpression of S100A4, PN-1, and LRP-1 in the medial layer of human TAA. Plasminogen activation taking place in the media of TAA was revealed by immunohistochemical staining and plasmin activity analyses. We showed by cell biology studies that plasmin-PN-1 complexes are internalized via LRP-1 in vSMCs from healthy and TAA media. Thus, two complementary mechanisms are involved in the protective role of PN-1 in human TAA: one involving plasmin inhibition and the other involving tissue clearance of plasmin-PN1 complexes via the scavenger receptor LRP-1.