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Abstract The authors present a short review of the personality, clinical and scientific contributions of a distinguished member of our Academy, the Artery Society and so many others, where he contributed landmark advances in many fields of arterial function and cardiovascular risk. The Editorial Board of the Artery Research Journal and the Executive Committee of the Artery Society present their due respects to Prof. Michel Safar.

IntroductionAmine oxidase copper containing 3 (AOC3) displays adhesion between leukocytes and endothelial cells and enzymatic functions. Given its controversial role in atherogenesis, we proposed to investigate the involvement of AOC3 in the formation of atherosclerotic plaques in ApoE−/−AOC3−/− mice and human coronary arteries.MethodsLesions, contractile markers, and AOC3 were studied in aortic tissues from 15- and 25-week-old mice and different stages of human coronary atherosclerotic arteries by immunohistochemistry (IHC) and/or western blot. Human VSMCs, treated or not with LJP1586, an AOC3 inhibitor, were used to measure differentiation markers by qPCR. AOC3 co-localization with specific cell markers was studied by using confocal microscopy in mice and human samples.ResultsAt 15 weeks old, the absence of AOC3 was associated with increased lesion size, α-SMA, and CD3 staining in the plaque independently of a cholesterol modification. At 25 weeks old, advanced plaques were larger with equivalent staining for α-SMA while CD3 increased in the media from ApoE−/−AOC3−/− mice. At both ages, the macrophage content of the lesion was not modified. Contractile markers decreased whereas MCP-1 appeared augmented only in the 15-week-old ApoE−/−AOC3. AOC3 is mainly expressed by mice and human VSMC is slightly expressed by endothelium but not by macrophages.ConclusionAOC3 knock-out increased atherosclerotic plaques at an early stage related to a VSMC dedifferentiation associated with a higher T cells recruitment in plaques explained by the MCP-1 augmentation. This suggests that AOC3 may have an important role in atherosclerosis independent of its canonical inflammatory effect. The dual role of AOC3 impacts therapeutic strategies using pharmacological regulators of SSAO activity.

Cardiovascular diseases remain an age-related pathology in both men and women. These pathologies are 3-fold more frequent in men than in women before menopause, although this difference progressively decreases after menopause. The vasculoprotective role of estrogens are well established before menopause, but the consequences of their abrupt decline on the cardiovascular risk at menopause remain debated. In this review, we will attempt to summarize the main clinical and experimental studies reporting the protective effects of estrogens against cardiovascular diseases, with a particular focus on atherosclerosis, and the impact of aging and estrogen deprivation on their endothelial actions. The arterial actions of estrogens, but also part of that of androgens through their aromatization into estrogens, are mediated by the estrogen receptor (ER)α and ERβ. ERs belong to the nuclear receptor family and act by transcriptional regulation in the nucleus, but also exert non-genomic/extranuclear actions. Beside the decline of estrogens at menopause, abnormalities in the expression and/or function of ERs in the tissues, and particularly in arteries, could contribute to the failure of classic estrogens to protect arteries during aging. Finally, we will discuss how recent insights in the mechanisms of action of ERα could contribute to optimize the hormonal treatment of the menopause.

Aims Although the risk of thrombosis is well documented for inflammatory bowel disease [IBD] patients, the underlying pathological mechanism seems to be different from other thrombotic conditions. Determining the factors responsible for the increased risk of thrombosis in IBD would help to improve the management of this frequent complication. Methods We studied the interplay between platelets, coagulation, and von Willebrand factor [VWF] in 193 IBD patients and in experimental models [acute and chronic] of colitis in wild-type and VWF-deficient mice. Results We found a platelet-dependent increase in thrombin generation in IBD patients and in our mouse model of colitis. Agglutinated platelets were present in the blood of patients and mice. Interestingly, we observed not only a significant increase in total VWF antigen, but we were also able to detect the presence of active VWF [VWF in its platelet-binding conformation; 3.2 ± 2.7 μg/mL] in the plasma of 30% of all IBD patients. In healthy controls, active VWF levels were <0.3 μg/mL. This led us to further explore experimental colitis in VWF-deficient mice and we observed that these mice were protected against the procoagulant state triggered by the colitis. Unexpectedly, these mice also showed a significant worsening of colitis severity in both acute and chronic models. Conclusion Platelets and VWF [including its active form] appear to be central players in the procoagulant phenotype in IBD. We observed that the role of VWF in haemostasis differs from its role in colonic tissue healing, potentially opening new therapeutic avenues for a life-threatening complication in IBD patients. [ABSTRACT FROM AUTHOR]

Background Short leukocyte telomere length (TL) is associated with atherosclerotic cardiovascular disease. Endothelial repair plays a key role in the development of atherosclerosis. The objective was to examine associations between TL and proliferative dynamics of endothelial colony‐forming cells (ECFCs), which behave as progenitor cells displaying endothelial repair activity. Methods and Results To isolate ECFCs, we performed a clonogenic assay on blood samples from 116 participants (aged 24–94 years) in the TELARTA (Telomere in Arterial Aging) cohort study. We detected no ECFC clones in 29 (group 1), clones with no replating capacity in other 29 (group 2), and clones with replating capacity in the additional 58 (group 3). Leukocyte TL was measured by Southern blotting and ECFCs (ECFC‐TL). Age‐ and sex‐adjusted leukocyte TL (mean±SEM) was the shortest in group 1 (6.51±0.13 kb), longer in group 2 (6.69±0.13 kb), and the longest in group 3 (6.78±0.09 kb) (P

In December 2019, an outbreak of pneumonia caused by a novel Coronavirus (COVID-19) spread rapidly worldwide. Although the clinical manifestations of COVID-19 are dominated by respiratory symptoms, the cardiovascular system is extensively affected at multiple levels. Due to the unprecedented consequences of the COVID-19 pandemic, the ARTERY society decided to launch the Covid-19 effects on ARTErial StIffness and vascular AgeiNg (CARTESIAN) study — the first international multicentre study into the effects of COVID-19 on non-invasive biomarkers of vascular ageing. The main study objective is to evaluate the presence of Early Vascular Ageing (EVA) 6 and 12 months after COVID-19 infection. Secondary objectives are to study the effect of COVID-19 disease severity on EVA, to investigate the role of psychosocial factors in COVID-19 induced EVA, and to investigate the potential modifying effect of comorbidities and chronic treatments. In the CARTESIAN study, a broad array of cardiovascular measurements, including carotid-femoral pulse wave velocity, central blood pressure, carotid ultrasound, brachial flow-mediated dilatation, will be performed. To date, 43 centres from 21 countries have agreed to participate, with an expected study population of >2500 individuals. To our knowledge, CARTESIAN will be the first study to provide insight into the relationship between COVID-19, its severity, and early vascular ageing in a large cohort, potentially enabling future care and diagnostics to be more focused on the most vulnerable.

Background and Objectives: Von Willebrand factor (VWF) is a plasma glycoprotein involved in primary hemostasis but recent data suggest additional roles beyond hemostasis in angiogenesis and potentially in vascular smooth muscle cell (VSMC) proliferation. Our aim was to investigate how VWF can modulate VSMC proliferation and identified the underlying mechanisms and the in vivo pathophysiological relevance. Methods and Results: Cultured aortic VSMCs proliferation and migration were increased in the presence of VWF. VSMCs treatment with a siRNA targeting αv integrin or the RGT-peptide blocking αvβ3 signaling completely inhibited proliferation. VWF did not bind directly to αvβ3 on VSMCs. We identified that VWF A2 domain was able to bind VSMCs. Since the low-density lipoprotein-related receptor protein (LRP) family are known to act as co-receptors we hypothesized the involvement of a member in the signaling pathway. Using the universal LRP-inhibitor (RAP), we confirmed LRP-mediated VSMC proliferation. siRNA experiments and proximity ligation assay staining identified LRP4 as the VWF-counterreceptor on VSMCs and showed co-localization between αvβ3 and LRP4. Carotid ligations were applied to VWF +/+ and −/− mice and intimal hyperplasia (IH) was measured. Less VWF−/− mice developed IH compared to VWF +/+ mice. Finally, the proliferative effect of VWF was confirmed in human atherosclerotic lesions from different vessels (aortas, carotids) showing a proximity between VWF and a-SM actin positive cells. Conclusions: VWF mediates VSMC proliferation through its A2 domain binding to the LRP4 receptor and integrin αvβ3 signaling. The decreased IH following vascular injury suggests that targeting VWF-LRP4 interactions may contribute to limit remodeling.

We and others propose vimentin as a possible cellular target for the treatment of COVID-19. This innovative idea is so recent that it requires further attention and debate. The significant role played by vimentin in virus-induced infection however is well established: (1) vimentin has been reported as a co-receptor and/or attachment site for SARS-CoV; (2) vimentin is involved in viral replication in cells; (3) vimentin plays a fundamental role in both the viral infection and the consequent explosive immune-inflammatory response and (4) a lower vimentin expression is associated with the inhibition of epithelial to mesenchymal transition and fibrosis. Moreover, the absence of vimentin in mice makes them resistant to lung injury. Since vimentin has a twofold role in the disease, not only being involved in the viral infection but also in the associated life-threatening lung inflammation, the use of vimentin-targeted drugs may offer a synergistic advantage as compared with other treatments not targeting vimentin. Consequently, we speculate here that drugs which decrease the expression of vimentin can be used for the treatment of patients with COVID-19 and advise that several Food and Drug Administration-approved drugs be immediately tested in clinical trials against SARS-CoV-2, thus broadening therapeutic options for this type of viral infection.

In contrast to abdominal aortic aneurysm (AAA), aneurysms of the thoracic ascending aorta (TAA) are not associated with a mural thrombus. Mechanistic understanding of the involvement of vascular smooth muscle cells (VSMCs) in thrombus formation is lacking. We aim to determine (i) whether thrombin generation at the surface of VSMCs is increased in AAA, (ii) the contribution of the avb3 integrin as a receptor for prothrombin, (iii) the implication of protease activated receptor (PAR) activation in the thrombin generation, and (iv) the capacity of thrombin to induce VSMC proliferation. Primary cultures of VSMCs were prepared from human biopsies of TAA, AAA and healthy aorta (n = 11/group). In the presence of prothrombin deficient plasma, similar low levels of thrombin were formed on the 3 types of VSMCs. In the presence of healthy plasma, thrombin generation was higher on VSMCs from AAA and lower on VSMCs from TAA compared with controls. Incubation of VSMCs with a RGT peptide inhibiting the b3 signaling reduced the amount of thrombin in the 3 groups. Incubation of healthy VSMCs with a selective PAR-1 antagonist decreased thrombin generation. This inhibition was more pronounced for AAA (36%) than from TAA (17%). VSMCs from AAA were more sensitive to thrombin-induced proliferation than VSMCs from TAA. The prothrombotic phenotype and proliferation of VSMCs from AAA compared to TAA is mediated partly by PAR-1. This argues for a contribution of VSMC in the occurrence of thrombotic events in AAA. Thus, inhibition of PAR signaling represents a new target in this complex disease.

It has been demonstrated that arterial stiffness is linked to arterial fibrosis manifested by increased collagen and other extracellular matrix synthesis in smooth muscle cells (SMC). Transmembrane receptors integrins mediating cell-cell and cell-matrix signalling pathways are involved in tissue fibrosis. We study the role of one integrin subunit av in angiotensin II (AngII)-induced SMC proliferation and arterial fibrosis and stiffness using SMC specific knock-out av mouse model (avSMKO) induced in adult mice by injection of tamoxifen. There is no difference in vascular fibrosis in basal conditions between control and mutant mice. However, decreased arterial fibrosis is observed in avSMKO mutant mice after 28-day perfusion of AngII. Analysis of RNA from aorta of control and mutant mice by Affymetrix microarrays indicated an alteration of the TGF-β pathway in AngII-treated mutant mice. In order to examine the mechanism associated to the decreased fibrosis in vascular SMC from avSMKO mice, isolated VSMC from the aorta of control and avSMKO mice were treated with TGF-β1 or AngII. The results indicated that these two treatments increased the expression of collagen, fibronectin and integrin αν at the protein and RNA levels as well as the phosphorylation of ERK and smad2/3 in the control cells. Inactivation of integrin αν partly inhibited all above effects induced by TGF-β1 and AngII. Our study indicates a role of av and TGF-β1 in the arterial fibrogenesis. Therefore, av signaling could be a therapeutic target against arterial fibrosis and stiffness in pathological conditions.

[This corrects the article DOI: 10.1371/journal.pone.0172995.].

Arterial stiffness has an independent predictive value for cardiovascular events. This review proposes an integrated view of the molecular determinants of arterial stiffness, based on a candidate gene approach, an analysis of the structure–function relationship in hypertension, and studies on gene expression profile in humans. In monogenic diseases of connective tissue (Marfan, Williams, and Ehlers–Danlos syndromes) and corresponding animal models, the precise characterization of arterial phenotype allows understanding the influence of abnormal, genetically determined, wall components on arterial stiffness. These studies underline the role of extra-cellular matrix signaling in the vascular wall and the fact that elastin and collagen have not only passive elastic or rigid properties, but also are implicated in the control of SMC function. In animal models of essential hypertension (SHR and SHR-SP), the structural modifications of the arterial wall include a higher number of elastin/SMC connections, and smaller fenestrations of the internal elastic lamina, which could redistribute the mechanical load towards elastic materials. Thus, the changes in arterial wall material which accompany wall hypertrophy in these animals are not associated with an increased stiffness. Taken together, these data afford strong arguments to consider that arterial stiffness is not only influenced by the amount and density of stiff wall material, but mainly by its spatial organization.

A calibrated automated thrombogram (CAT) is performed usually with human platelet-free plasma (PFP) but may be more relevant with platelet-rich plasma (PRP). In this case, platelets are not stimulated by subendothelial molecules like collagen. Our aim was to assess the consequence of strong (collagen) or weak (ADP) induction of platelet release and aggregation on thrombin generation. Platelet aggregation in PRP was triggered with 10 µg/mL collagen or 10 µM ADP using a lumi-aggregometer. Thrombin generation curves were monitored by CAT in different conditions: PRP, PRP with activated platelets (actPRP), aggregated PRP (agPRP), aggregated platelets resuspended in autologous PFP (resPRP), PFP and PFP obtained after aggregation (agPFP). We found a 3-fold shortening of the lag time and time to peak and a marked increase in velocity and thrombin peak without changes in endogenous thrombin potential (ETP) in agPRP with both agonists compared with PRP. The same holds true in agPFP but with a marked increase in ETP compared with PFP. Similar changes in the kinetics of thrombin generation were observed with actPRP-collagen and to a lesser extent in resPRP-collagen compared with PRP. By contrast, there were no modifications of the thrombin generation curves in actPRP-ADP. Alpha-2-macroglobin-thrombin complexes were unchanged in the different PRP conditions but were increased in PFP prepared from agPFP compared to control PFP. Platelet aggregation during activation by agonists other than thrombin did not increase thrombin generation but accelerated its kinetics mainly via platelet content release and platelet-derived extracellular vesicules formation. In diseases characterized by altered platelet granule content or release as well as altered platelet activation, a platelet aggregation step prior to CAT analysis may be clinically relevant to improve laboratory estimation of the bleeding/thrombotic balance.

The RhoA signaling pathway is a master regulator of mechanostransduction and plasticity of vascular smooth muscle cells (VSMCs) that controls arterial stiffening. The RhoA exchange factor Arhgef1 is causally involved in the development of angiotensin II-dependent hypertension. Our aim was to determine whether Arhgef1 plays a key role in age-associated arterial stiffness and the coupling with modifications of the procoagulant properties of blood and VSMCs. We used 65 week-old transgenic mice invalidated for Arhgef1 (Arhgef1−/−) and age-matched controls (Arhgef1+/+). In vivo arterial diameter pressure, distensibility/arterial pressure and elastic modulus/circumferential stress curves at the level of carotid artery were recorded using an echotracking system (VEVO 770 Visualsonics Imaging) in anesthetized animals. Systolic blood pressure, pulse pressure and heart rate were not different between mutant and control mice. Isobaric carotid distensibility was increased in Arhgef1−/− mice compared to Arhgef1+/+ mice. The elastic modulus/circumferential stress curves were shifted significantly rightwards in Arhgef1−/− mice compared to Arhgef1+/+ mice. Thrombin generation in blood and at the surface of VSMCs cultured from aorta was reduced in Arhgef1−/− mice. Anticoagulant markers secreted by the vascular wall (tissue factor pathway inhibitor and thrombomodulin) were increased in plasma of Arhgef1−/− mice. The time of formation of an occlusive thrombus induced by FeCl3 in the carotid artery was prolonged in Arhgef1−/− mice. In conclusion, the Arhgef1/RhoA contractile pathway contributes to arterial stiffening and VSMC procoagulant properties in aging. Whether this reduced procoagulant properties of the vascular wall is a cause or consequence of arterial stiffness remains to be elucidated.

Hypertension and arterial aging engage a plethora of key signaling pathways that act in concert to induce vascular smooth muscle cell (VSMC) phenotypic changes leading to vascular degeneration and extracellular matrix (ECM) changes responsible for alterations of the mechanical properties of the vascular wall. This review highlights proof-of-concept examples of components of the extracellular matrix, VSMC receptors which connect extracellular and intracellular structures and signaling pathways regulating changes in mechanotransduction and vascular homeostasis. This presentation presents new directions in the role of vascular smooth muscle cells VSMCs traditionally limited to regulation of contractile properties and synthesis of ECM proteins. VSMCs may exert negative feedback or positive feedback on ECM stiffness and mechanical load via stabilized focal adhesions, activated Rho-ROCK signaling pathways or actomyosin contraction. Understanding the mechanisms of cellular stiffness are also important to appreciate its contribution to mechanical properties at the tissue-level. Many other cell types, including macrophages, could participate to inflammation and VSMC stiffness leading to fibrosis of the arterial wall. In view of the multitude roles of VSMCs and feedback controls, only omic approaches and computational models may extrapolate the overall effects on the vascular wall in light of hemodynamics and complex interactions amongst differentially sized vessels. The use of novel animal models with multiple genetic manipulations of VSMC signaling pathways can provide further insight into the link between large vessel stiffness and small vessel dysfunction.

Background: Pulse wave velocity (PWV) is a marker of arterial stiffness, which is intrinsically highly correlated with blood pressure (BP). However, the interplay of PWV and BP heritability has not been extensively studied. This study aimed to estimate the heritability of PWV and BP and determine the genetic correlation between PWV and BP. Methods: The heritability of PWV and BP was estimated in 1080 subjects from the STANISLAS (Suivi Temporaire Annuel Non-Invasif de la Santé des Lorrains Assurés Sociaux) cohort with at least one relative using a linear mixed model within one frequentist and one Bayesian framework implemented, respectively, in the Gaston and MCMCglmm R packages. Then their genetic correlations were also estimated. Results: The heritability estimations for PWV were within the same range of the heritability of systolic BP and diastolic BP (23%, 19%, and 27%, respectively). Daytime heritability of BP was higher than nighttime BP. In addition, phenotypic correlations between PWV and systolic BP/diastolic BP were, respectively, 0.34 and 0.23, whereas nonsignificant genetic correlations were 0.08 and 0.22 respectively, indicating that PWV and diastolic BP shared more polygenic codeterminants than PWV and systolic BP. Conclusions: Our results suggest that the heritability of PWV is >20% and within the same range as BP heritability. It also suggests that the link between PWV and BP goes beyond phenotypic association: PWV and BP (in particular diastolic BP) share common genetic determinants. This genetic interdependence of PWV and BP appears largely polygenic. [ABSTRACT FROM AUTHOR]

Background: The metabolic syndrome (MetS) and aging are associated with modifications in blood coagulation factors, vascular inflammation, and increased risk of thrombosis.Objectives: Our aim was to determine concomitant changes in thrombin generation in the blood compartment and at the surface of vascular smooth muscle cells (VSMCs) and its interplay with adipokines, free fatty acids (FFA), and metalloproteinases (MMPs) in obese Zucker rats that share features of the human MetS.Methods: Obese and age-matched lean Zucker rats were compared at 25 and 80 weeks of age. Thrombin generation was assessed by calibrated automated thrombography (CAT).Results: Endogenous thrombin potential (ETP) was increased in obese rats independent of platelets and age. Clot half-lysis time was delayed with obesity and age. Interleukin (IL)-1β and IL-13 were increased with obesity and age respectively. Addition of exogenous fibrinogen, leptin, linoleic, or palmitic acid increased thrombin generation in plasma whereas adiponectin had an opposite effect. ETP was increased at the surface of VSMCs from obese rats and addition of exogenous palmitic acid further enhanced ETP values. Gelatinase activity was increased in aorta at both ages in obese rats and MMP-2 activity was increased in VSMCs from obese rats.Conclusions: Our study demonstrated in MetS an early prothrombotic phenotype of the blood compartment reinforced by procoagulant properties of dedifferentiated and inflammatory VSMCs. Mechanisms involved (1) increased fibrinogen and impaired fibrinolysis and (2) increased saturated fatty acids responsible for additive procoagulant effects. Whether specifically targeting this hypercoagulability using direct thrombin inhibitors would improve outcome in MetS is worth investigating.

AimsDilated cardiomyopathy (DCM) is an important cause of heart failure with a strong familial component. We performed an exome-wide array-based association study (EWAS) to assess the contribution of missense variants to sporadic DCM.Methods and results116,855 single nucleotide variants (SNVs) were analyzed in 2796 DCM patients and 6877 control subjects from 6 populations of European ancestry. We confirmed two previously identified associations with SNVs in BAG3 and ZBTB17 and discovered six novel DCM-associated loci (Q-valueConclusionWe identified eight loci independently associated with sporadic DCM. The functions of the best candidate genes at these loci suggest that proteostasis regulation might play a role in DCM pathophysiology.

Integrin αv functions as a receptor for adhesion proteins and is expressed at high density in vascular smooth muscle cells (VSMC)1,2,3,4,5 whose phenotypic modulation plays a crucial role in arterial ageing and atherosclerosis.6,7. Our aim was to define the arterial phenotype in mice conditionally inactivated for the integrin αv subunit in VSMC8,9,10(αv SMKO) and its role in angiotensin II (AngII)-induced arterial fibrosis. Transgenic mice αv SMKO and their control littermates (WT) were treated with two doses of AngII, low (0.3 mg/kg/day) and high (1.5 mg/kg/day), for 4 weeks. At baseline, blood pressure was lower in αvSMKO compared to WT mice. Carotid distensibility was increased in αv SMKO mice (13.3±0.7 vs 10.3±0.6 mmHg−1.10−3). With low dose AngII isobaric distensibility remained higher in αvSMKOmice (12.4±1.2 vs 10.7±1.0 mmHg−1.10−3).With high dose AngII the increase in collagen content in carotid media was lower in αvSMKOthan in WT (19 vs 35%) for a similar increase in blood pressure (30 mmHg) and arterial wall hypertrophy. Collagen immunostaining and fluorescence measurements (multiphoton microscopy second harmonic generation) confirmed that high dose AngII induced lower increases in collagen content in αvSMKO mice versus WT (8.9±1.7 vs 14.2±1.4 greyscale mean/pixel). The combination of similar arterial wall hypertrophy with less fibrosis in mutant mice explains an increased distensibility in response to AngII. The αv subunit regulates AngII-induced arterial fibrosis as determined by collagen staining, immunostaining and fluorescence. Pharmacological targeting of vascular αv integrin may have clinical applications in the treatment of patients with fibrosis associated with hypertension and atherosclerosis.

Background: SNPs on chromosome 9p21.3 risk locus have been associated with cardiovascular diseases. We have established a direct mechanistic link between 9p21 noncoding risk interval and susceptibility to aneurysm in a mouse model with a targeted deletion of the 9p21 noncoding cardiovascular disease risk interval. The deficiency of transcripts encoded by this locus predisposes to a pro-thrombotic phenotype and arterial stiffening in this mouse model and in humans with 9p21 DNA variants. Methods: Carotid blood flow following FeCl3 application was monitored via Doppler profiles. Results: The deletion of the orthologous 70-kb noncoding interval on mouse chromosome 4 (chr4Δ70kb/Δ70kb), synthetic to human chromosome 9p21, predisposes to arterial thrombosis. The time to occlusion in a FeCl3-induced carotid thrombosis model was significantly decreased by 30% in the absence of the locus and confirmed by a new model of physiological thrombosis. There was no difference between groups in blood pressure, carotid stiffness parameters (diameter and distensibility for a given level of arterial pressure) or in vascular structure. We explored the potential impact of the deletion locus on thrombin generation as well as on platelet aggregation and reactivity all were increased compared to controls. In 100 healthy carriers of the 9p21 risk T allele display an increased aortic arterial stiffness compared with carriers of the C allele. Conclusion: These results establish a direct link between variants or deletion in the 9p21 non-coding risk interval and increased platelet reactivity and thrombin generation predisposing to thrombosis in mouse and increased arterial stiffness in aged population.

Platelet activation by thrombin is an auto-amplification loop of thrombin generation, a major factor in the formation of atherosclerotic plaques. The small G protein RhoA, under the direct control of the exchange factor Arhgef1, modulates several cellular functions in inflammation. The objective was to study the RhoA pathway and its control by Arhgef1 in platelet aggregation and thrombin generation due to PAR receptor activation by thrombin. We used a knockout mouse model for the exchange factor Arhgef1 (Arhgef1 −/−). In response to an agonist (collagen, ADP and thrombin), the expression of surface glycoproteins and the aggregation of washed platelets were not altered in the Arhgef1 −/− mice compared to Argef1 +/+ mice. In contrast, platelet activation studied by the secretion of granules a, exposure to phosphatidylserine and release of microparticles were decreased in the Arhgef1 −/− mice. Thrombin generation in whole platelet-rich blood was also reduced by 25%. These changes result in a lengthening of the time of occurrence of an occlusive thrombus in the carotid induced by FeCl3. In conclusion, the results confirm the involvement of the RhoA pathway in platelet activation and demonstrate an Arhgef1-dependent mechanism. The results in mice show a new auto-amplification mechanism of thrombin generation by platelets through PAR and membrane phospholipids. Redistribution of phospholipid linked rearrangements of the membrane complex induced by inflammation suggests that the RhoA pathway potentiates the deleterious effects of thrombin in atherothrombosis.

Background: Short leukocyte telomere length (LTL) is associated with atherosclerosis. The prevailing view is this association exists since LTL is a biomarker of cumulative inflammation and oxidative stress during adult life. However recent studies show that LTL in adults is defined mainly by LTL at birth and attrition during childhood. Therefore we can suggest that short LTL might precede clinical expression of atherosclerosis. Objectives: To examine the directionality in the relation between carotid atheroma and LTL dynamics. Methods: LTL was measured by TRF in samples donated 9 years apart on average by 257 men and women aged 41 to 80 at the inclusion. Results: LTL attrition during follow-up (FU) period was 25±17 bp/year. No relation was observed between LTL attrition and presence of carotid atherosclerotic plaques (PCAP). Baseline (BL)-LTL was highly correlated (r=0.96, p

Purpose/Background/Objectives: Obesity is a well-known risk factor of cardiovascular diseases and a potentially modifiable determinant of arterial ageing. The objectives of this experimental study were to assess the effects of a long-term high fat diet (HFD) on metabolism, adipose tissues and phenotypes of cardiovascular aging. Methods: Murine model chosen was C57BL/6J mice receiving during one year HFD or control diet (CD). Longitudinal follow-up of weight, systolic bloodpressure, heart rate and metabolic parameters was performed. An echocardiographic system was used to study cardiac function. Metabolism at the level of the adipose tissues was studied with FDG positron emission tomography (PET). Results: After 12 months of diet the whole mice showed a positive correlation between plasma leptin level and left ventricular thickness and mass (both p

Integrin avb3 is expressed at high density in vascular smooth muscle cells (VSMCs). It functions as a receptor for adhesion proteins in VSMCs which phenotypic modulation plays a pivotal role in arteriosclerosis and atherosclerosis. The aim was to study the role of integrin avb3 in angiotensin II (Ang II)-induced arterial fibrosis in mice and in human samples of atherosclerotic arteries in situ. Transgenic mice conditionally inactivated for integrin av subunit in VSMCs (avSMKO) were treated with Ang II (1,5 mg/kg/day) for 4 weeks. Immunostained slices of atherosclerotic plaques at different stages of development and primary cultures of human aortic VSMCs were used. At baseline, blood pressure was lower in avSMKO compared to control (WT) mice. Isobaric carotid distensibility was increased and remained higher in avSMKO in response to Ang II. The increase in collagen content in response to Ang II was lower in avSMKO than in WT (15 vs 36%) for similar increase in blood pressure (20 mmHg) and arterial wall hypertrophy. The immunohistochemistry of aortic slices showed stronger staining for integrin avb3 in atherosclerotic plaques compared to healthy aortas. In VSMC cultures, the mRNA of av was decreased. In conclusion, these results show that avb3 is strongly expressed in neointimal proliferation and in fibrous plaques. The av integrin subunit seems to regulate arterial fibrosis in response to hypertension and plaque growth. Low RNA quantities of av subunit of VSMCs contrasted with strong protein staining in plaques suggesting the participation of inflammatory cells in the synthesis of this integrin.

Individuals with metabolic syndrome (MetS) are prone to develop heart failure (HF). However, the deleterious effects of MetS on the continuum of events leading to cardiac remodeling and subsequently to HF are not fully understood. This study characterized simultaneously MetS and cardiac, vascular and renal phenotypes in aging Spontaneously Hypertensive Heart Failure lean (SHHF(+/?) regrouping (+/+) and (+/cp) rats) and obese (SHHF(cp/cp), "cp" defective mutant allele of the leptin receptor gene) rats. We aimed to refine the milestones and their onset during the progression from MetS to HF in this experimental model. We found that SHHF(cp/cp )but not SHHF(+/?) rats developed dyslipidemia, as early as 1.5 months of age. This early alteration in the lipidic profile was detectable concomitantly to impaired renal function (polyuria, proteinuria but no glycosuria) and reduced carotid distensibility as compared to SHHF(+/?) rats. By 3 months of age SHHFcp/cp animals developed severe obesity associated with dislipidemia and hypertension defining the onset of MetS. From 6 months of age, SHHF(+/?) rats developed concentric left ventricular hypertrophy (LVH) while SHHF(cp/cp) rats developed eccentric LVH apparent from progressive dilation of the LV dimensions. By 14 months of age only SHHF(cp/cp) rats showed significantly higher central systolic blood pressure and a reduced ejection fraction resulting in systolic dysfunction as compared to SHHF(+/?). In summary, the metabolic and hemodynamic mechanisms participating in the faster decline of cardiac functions in SHHF(cp/cp) rats are established long before their physiological consequences are detectable. Our results suggest that the molecular mechanisms triggered within the first three months after birth of SHHF(cp/cp) rats should be targeted preferentially by therapeutic interventions in order to mitigate the later HF development.

Objectives: The metabolic syndrome (MetS), a cluster of risk factor including abdominal fat, hypertension, dyslipidemia and raised fasting plasma glucose, is associated with modifications in the arterial wall, endothelial dysfunction and atherothrombosis. To explore the course of events we characterized the coagulation, fibrinolysis and vascular phenotypes in 25 and 80-week-old Zucker rats, that mimics human MetS. Methods: Arterial phenotype was assessed using ultrasonic echo-tracking. Thrombin generation was monitored using calibrated automated thrombography. Fibrinolysis was measured by a clot lysis assay. Results: Endothelial dysfunction was evidenced by a high plasma concentration of von Willebrand factor at both ages. The arterial wall stress/modulus curves were superimposed at 25 weeks and shifted towards the left with age, the shift being more pronounced in obese rats. Media thickness was not modified with MetS but was increased with aging in obese and lean rats. In vitro thrombin generation was higher in 25-week-old obese rats than in age-matched control lean rats (428±29 versus 328±27 nM.min) and still higher at 80 weeks (422±30 versus 306±11 nM.min). Regarding fibrinolysis, half-time lysis clot was increased in obese rats compared to control lean rats (46.5±1.2 versus 41.5±0.7 min at 25 weeks) and increased with age (54.1±1.1 versus 49.3±1.8 min at 80 weeks). Conclusions: We have shown that thrombin generation increased and fibrinolysis decreased in vitro with obesity as early as 25 weeks of age. Theses alterations of hemostasis may participate to the accelerated arterial aging as assessed by increased arterial stiffness triggered by obesity and metabolic disorders in SMet.

Rationale: Vascular smooth muscle cell (VSMC) phenotypic modulation plays an important role in arterial stiffening associated with ageing. Serum response factor (SRF) is a major transcription factor regulating smooth muscle (SM) genes involved in maintenance of the contractile state of VSMCs. Objective: We investigated whether SRF and its target genes regulate intrinsic SM-tone and thereby arterial stiffness. Methods and results: The SRF gene was inactivated (SRFSMKO) specifically in VSMCs by injection of tamoxifen into adult transgenic mice. Fifteen days later, arterial pressure and carotid thickness were lower in SRFSMKO than in control mice. The carotid distensibility/pressure and elastic modulus/wall stress curves showed a greater arterial elasticity in SRFSMKO without modification in collagen/elastin ratio. In SRFSMKO, vasodilation was decreased in aorta and carotid arteries whereas a decrease in contractile response was found in mesenteric arteries. By contrast, in mice with inducible SRF overexpression, the in vitro contractile response was significantly increased in all arteries. Without endothelium, the contraction was reduced in SRFSMKO compared with control aortic rings due to impairment of the NO pathway. Contractile components (SM-actin and myosin light chain), regulators of the contractile response (myosin light chain kinase, myosin phosphatase target subunit 1 and protein kinase C-potentiated myosin phosphatase inhibitor) and integrins were reduced in SRFSMKO. Conclusion: SRF controls vasoconstriction in mesenteric arteries via VSMC phenotypic modulation linked to changes in contractile protein gene expression. SRF-related decreases in vasomotor tone and cell-matrix attachment increase arterial elasticity in large arteries.