Neuroimmune cardiovascular interfaces control atherosclerosis.

Atherosclerotic plaques develop in the inner intimal layer of arteries and can cause heart attacks and strokes1. As plaques lack innervation, the effects of neuronal control on atherosclerosis remain unclear. However, the immune system responds to plaques by forming leukocyte infiltrates in the outer connective tissue coat of arteries (the adventitia)2-6. Here, because the peripheral nervous system uses the adventitia as its principal conduit to reach distant targets7-9, we postulated that the peripheral nervous system may directly interact with diseased arteries. Unexpectedly, widespread neuroimmune cardiovascular interfaces (NICIs) arose in mouse and human atherosclerosis-diseased adventitia segments showed expanded axon networks, including growth cones at axon endings near immune cells and media smooth muscle cells. Mouse NICIs established a structural artery-brain circuit (ABC): abdominal adventitia nociceptive afferents10-14 entered the central nervous system through spinal cord T6-T13 dorsal root ganglia and were traced to higher brain regions, including the parabrachial and central amygdala neurons; and sympathetic efferent neurons projected from medullary and hypothalamic neurons to the adventitia through spinal intermediolateral neurons and both coeliac and sympathetic chain ganglia. Moreover, ABC peripheral nervous system components were activated: splenic sympathetic and coeliac vagus nerve activities increased in parallel to disease progression, whereas coeliac ganglionectomy led to the disintegration of adventitial NICIs, reduced disease progression and enhanced plaque stability. Thus, the peripheral nervous system uses NICIs to assemble a structural ABC, and therapeutic intervention in the ABC attenuates atherosclerosis.

JCAD promotes arterial thrombosis through PI3K/Akt modulation: a translational study.

AIMS: Variants of the junctional cadherin 5 associated (JCAD) locus associate with acute coronary syndromes. JCAD promotes experimental atherosclerosis through the large tumor suppressor kinase 2 (LATS2)/Hippo pathway. This study investigates the role of JCAD in arterial thrombosis. METHODS AND RESULTS: JCAD knockout (Jcad-/-) mice underwent photochemically induced endothelial injury to trigger arterial thrombosis. Primary human aortic endothelial cells (HAECs) treated with JCAD small interfering RNA (siJCAD), LATS2 small interfering RNA (siLATS2) or control siRNA (siSCR) were employed for in vitro assays. Plasma JCAD was measured in patients with chronic coronary syndrome or ST-elevation myocardial infarction (STEMI). Jcad-/- mice displayed reduced thrombogenicity as reflected by delayed time to carotid occlusion. Mechanisms include reduced activation of the coagulation cascade [reduced tissue factor (TF) expression and activity] and increased fibrinolysis [higher thrombus embolization episodes and D-dimer levels, reduced vascular plasminogen activator inhibitor (PAI)-1 expression]. In vitro, JCAD silencing inhibited TF and PAI-1 expression in HAECs. JCAD-silenced HAECs (siJCAD) displayed increased levels of LATS2 kinase. Yet, double JCAD and LATS2 silencing did not restore the control phenotype. si-JCAD HAECs showed increased levels of phosphoinositide 3-kinases (PI3K)/ proteinkinase B (Akt) activation, known to downregulate procoagulant expression. The PI3K/Akt pathway inhibitor-wortmannin-prevented the effect of JCAD silencing on TF and PAI-1, indicating a causative role. Also, co-immunoprecipitation unveiled a direct interaction between JCAD and Akt. Confirming in vitro findings, PI3K/Akt and P-yes-associated protein levels were higher in Jcad-/- animals. Lastly, as compared with chronic coronary syndrome, STEMI patients showed higher plasma JCAD, which notably correlated positively with both TF and PAI-1 levels. CONCLUSIONS: JCAD promotes arterial thrombosis by modulating coagulation and fibrinolysis. Herein, reported translational data suggest JCAD as a potential therapeutic target for atherothrombosis.

Long Noncoding RNA MIAT Controls Advanced Atherosclerotic Lesion Formation and Plaque Destabilization.

BACKGROUND: Long noncoding RNAs (lncRNAs) are important regulators of biological processes involved in vascular tissue homeostasis and disease development. The present study assessed the functional contribution of the lncRNA myocardial infarction-associated transcript (MIAT) to atherosclerosis and carotid artery disease. METHODS: We profiled differences in RNA transcript expression in patients with advanced carotid artery atherosclerotic lesions from the Biobank of Karolinska Endarterectomies. The lncRNA MIAT was identified as the most upregulated noncoding RNA transcript in carotid plaques compared with nonatherosclerotic control arteries, which was confirmed by quantitative real-time polymerase chain reaction and in situ hybridization. RESULTS: Experimental knockdown of MIAT, using site-specific antisense oligonucleotides (LNA-GapmeRs) not only markedly decreased proliferation and migration rates of cultured human carotid artery smooth muscle cells (SMCs) but also increased their apoptosis. MIAT mechanistically regulated SMC proliferation through the EGR1 (Early Growth Response 1)-ELK1 (ETS Transcription Factor ELK1)-ERK (Extracellular Signal-Regulated Kinase) pathway. MIAT is further involved in SMC phenotypic transition to proinflammatory macrophage-like cells through binding to the promoter region of KLF4 and enhancing its transcription. Studies using Miat-/- and Miat-/-ApoE-/- mice, and Yucatan LDLR-/- mini-pigs, as well, confirmed the regulatory role of this lncRNA in SMC de- and transdifferentiation and advanced atherosclerotic lesion formation. CONCLUSIONS: The lncRNA MIAT is a novel regulator of cellular processes in advanced atherosclerosis that controls proliferation, apoptosis, and phenotypic transition of SMCs, and the proinflammatory properties of macrophages, as well.

Vascular dysfunction in COVID-19 patients: update on SARS-CoV-2 infection of endothelial cells and the role of long non-coding RNAs.

Although COVID-19 is primarily a respiratory disease, it may affect also the cardiovascular system. COVID-19 patients with cardiovascular disorder (CVD) develop a more severe disease course with a significantly higher mortality rate than non-CVD patients. A common denominator of CVD is the dysfunction of endothelial cells (ECs), increased vascular permeability, endothelial-to-mesenchymal transition, coagulation, and inflammation. It has been assumed that clinical complications in COVID-19 patients suffering from CVD are caused by SARS-CoV-2 infection of ECs through the angiotensin-converting enzyme 2 (ACE2) receptor and the cellular transmembrane protease serine 2 (TMPRSS2) and the consequent dysfunction of the infected vascular cells. Meanwhile, other factors associated with SARS-CoV-2 entry into the host cells have been described, including disintegrin and metalloproteinase domain-containing protein 17 (ADAM17), the C-type lectin CD209L or heparan sulfate proteoglycans (HSPG). Here, we discuss the current data about the putative entry of SARS-CoV-2 into endothelial and smooth muscle cells. Furthermore, we highlight the potential role of long non-coding RNAs (lncRNAs) affecting vascular permeability in CVD, a process that might exacerbate disease in COVID-19 patients.

Single-Cell RNA-Seq Reveals the Transcriptional Landscape and Heterogeneity of Aortic Macrophages in Murine Atherosclerosis.

RATIONALE: It is assumed that atherosclerotic arteries contain several macrophage subsets endowed with specific functions. The precise identity of these subsets is poorly characterized as they have been defined by the expression of a restricted number of markers. OBJECTIVE: We have applied single-cell RNA sequencing as an unbiased profiling strategy to interrogate and classify aortic macrophage heterogeneity at the single-cell level in atherosclerosis. METHOD AND RESULTS: We performed single-cell RNA sequencing of total aortic CD45+ cells extracted from the nondiseased (chow fed) and atherosclerotic (11 weeks of high-fat diet) aorta of low-density lipoprotein receptor-deficient (Ldlr-/-) mice. Unsupervised clustering singled out 13 distinct aortic cell clusters. Among the myeloid cell populations, resident-like macrophages with a gene expression profile similar to aortic resident macrophages were found in healthy and diseased aortas, whereas monocytes, monocyte-derived dendritic cells, and 2 populations of macrophages were almost exclusively detectable in atherosclerotic aortas, comprising inflammatory macrophages showing enrichment in Il1b and previously undescribed TREM2hi (triggered receptor expressed on myeloid cells 2) macrophages showing enrichment in Trem2. Differential gene expression and gene ontology enrichment analyses revealed specific gene expression patterns distinguishing these 3 macrophage subsets and monocyte-derived dendritic cells and uncovered putative functions of each cell type. Notably, TREM2hi macrophages seemed to be endowed with specialized functions in lipid metabolism and catabolism and presented a gene expression signature reminiscent of osteoclasts, suggesting a role in lesion calcification. TREM2 expression was moreover detected in human lesional macrophages. Importantly, these macrophage populations were present also in advanced atherosclerosis and in Apoe-/- aortas, indicating relevance of our findings in different stages of atherosclerosis and mouse models. CONCLUSIONS: These data unprecedentedly uncovered the transcriptional landscape and phenotypic heterogeneity of aortic macrophages and monocyte-derived dendritic cells in atherosclerotic and identified previously unrecognized macrophage populations and their gene expression signature, suggesting specialized functions. Our findings will open up novel opportunities to explore distinct myeloid cell populations and their functions in atherosclerosis.

The novel coronary artery disease risk gene JCAD/KIAA1462 promotes endothelial dysfunction and atherosclerosis.

AIMS: Recent genome-wide association studies (GWAS) have identified that the JCAD locus is associated with risk of coronary artery disease (CAD) and myocardial infarction (MI). However, the mechanisms whereby candidate gene JCAD confers disease risk remain unclear. We addressed whether and how JCAD affects the development of atherosclerosis, the common cause of CAD. METHODS AND RESULTS: By mining data in the Genotype-Tissue Expression (GTEx) database, we found that CAD-associated risk variants at the JCAD locus are linked to increased JCAD gene expression in human arteries, implicating JCAD as a candidate causal CAD gene. We therefore generated global and endothelial cell (EC) specific-JCAD knockout mice, and observed that JCAD deficiency attenuated high fat diet-induced atherosclerosis in ApoE-deficient mice. JCAD-deficiency in mice also improved endothelium-dependent relaxation. Genome-wide transcriptional profiling of JCAD-depleted human coronary artery ECs showed that JCAD depletion inhibited the activation of YAP/TAZ pathway, and the expression of downstream pro-atherogenic genes, including CTGF and Cyr61. As a result, JCAD-deficient ECs attracted fewer monocytes in response to lipopolysaccharide (LPS) stimulation. Moreover, JCAD expression in ECs was decreased under unidirectional laminar flow in vitro and in vivo. Proteomics studies suggest that JCAD regulates YAP/TAZ activation by interacting with actin-binding protein TRIOBP, thereby stabilizing stress fiber formation. Finally, we observed that endothelial JCAD expression was increased in mouse and human atherosclerotic plaques. CONCLUSION: The present study demonstrates that the GWAS-identified CAD risk gene JCAD promotes endothelial dysfunction and atherosclerosis, thus highlighting the possibility of new therapeutic strategies for CAD by targeting JCAD.

H19 Induces Abdominal Aortic Aneurysm Development and Progression.

BACKGROUND: Long noncoding RNAs have emerged as critical molecular regulators in various biological processes and diseases. Here we sought to identify and functionally characterize long noncoding RNAs as potential mediators in abdominal aortic aneurysm development. METHODS: We profiled RNA transcript expression in 2 murine abdominal aortic aneurysm models, Angiotensin II (ANGII) infusion in apolipoprotein E-deficient ( ApoE-/-) mice (n=8) and porcine pancreatic elastase instillation in C57BL/6 wild-type mice (n=12). The long noncoding RNA H19 was identified as 1 of the most highly upregulated transcripts in both mouse aneurysm models compared with sham-operated controls. This was confirmed by quantitative reverse transcription-polymerase chain reaction and in situ hybridization. RESULTS: Experimental knock-down of H19, utilizing site-specific antisense oligonucleotides (LNA-GapmeRs) in vivo, significantly limited aneurysm growth in both models. Upregulated H19 correlated with smooth muscle cell (SMC) content and SMC apoptosis in progressing aneurysms. Importantly, a similar pattern could be observed in human abdominal aortic aneurysm tissue samples, and in a novel preclinical LDLR-/- (low-density lipoprotein receptor) Yucatan mini-pig aneurysm model. In vitro knock-down of H19 markedly decreased apoptotic rates of cultured human aortic SMCs, whereas overexpression of H19 had the opposite effect. Notably, H19-dependent apoptosis mechanisms in SMCs appeared to be independent of miR-675, which is embedded in the first exon of the H19 gene. A customized transcription factor array identified hypoxia-inducible factor 1α as the main downstream effector. Increased SMC apoptosis was associated with cytoplasmic interaction between H19 and hypoxia-inducible factor 1α and sequential p53 stabilization. Additionally, H19 induced transcription of hypoxia-inducible factor 1α via recruiting the transcription factor specificity protein 1 to the promoter region. CONCLUSIONS: The long noncoding RNA H19 is a novel regulator of SMC survival in abdominal aortic aneurysm development and progression. Inhibition of H19 expression might serve as a novel molecular therapeutic target for aortic aneurysm disease.

MicroRNA-210 Enhances Fibrous Cap Stability in Advanced Atherosclerotic Lesions.

RATIONALE: In the search for markers and modulators of vascular disease, microRNAs (miRNAs) have emerged as potent therapeutic targets. OBJECTIVE: To investigate miRNAs of clinical interest in patients with unstable carotid stenosis at risk of stroke. METHODS AND RESULTS: Using patient material from the BiKE (Biobank of Karolinska Endarterectomies), we profiled miRNA expression in patients with stable versus unstable carotid plaque. A polymerase chain reaction-based miRNA array of plasma, sampled at the carotid lesion site, identified 8 deregulated miRNAs (miR-15b, miR-29c, miR-30c/d, miR-150, miR-191, miR-210, and miR-500). miR-210 was the most significantly downregulated miRNA in local plasma material. Laser capture microdissection and in situ hybridization revealed a distinct localization of miR-210 in fibrous caps. We confirmed that miR-210 directly targets the tumor suppressor gene APC (adenomatous polyposis coli), thereby affecting Wnt (Wingless-related integration site) signaling and regulating smooth muscle cell survival, as well as differentiation in advanced atherosclerotic lesions. Substantial changes in arterial miR-210 were detectable in 2 rodent models of vascular remodeling and plaque rupture. Modulating miR-210 in vitro and in vivo improved fibrous cap stability with implications for vascular disease. CONCLUSIONS: An unstable carotid plaque at risk of stroke is characterized by low expression of miR-210. miR-210 contributes to stabilizing carotid plaques through inhibition of APC, ensuring smooth muscle cell survival. We present local delivery of miR-210 as a therapeutic approach for prevention of atherothrombotic vascular events.

Local Delivery of miR-21 Stabilizes Fibrous Caps in Vulnerable Atherosclerotic Lesions.

miRNAs are potential regulators of carotid artery stenosis and concordant vulnerable atherosclerotic plaques. Hence, we analyzed miRNA expression in laser captured micro-dissected fibrous caps of either ruptured or stable plaques (n = 10 each), discovering that miR-21 was significantly downregulated in unstable lesions. To functionally evaluate miR-21 in plaque vulnerability, miR-21 and miR-21/apolipoprotein-E double-deficient mice (Apoe-/-miR-21-/-) were assessed. miR-21-/- mice lacked sufficient smooth muscle cell proliferation in response to carotid ligation injury. When exposing Apoe-/-miR-21-/- mice to an inducible plaque rupture model, they presented with more atherothrombotic events (93%) compared with miR-21+/+Apoe-/- mice (57%). We discovered that smooth muscle cell fate in experimentally induced advanced lesions is steered via a REST-miR-21-REST feedback signaling pathway. Furthermore, Apoe-/-miR-21-/- mice presented with more pronounced atherosclerotic lesions, greater foam cell formation, and substantially higher levels of arterial macrophage infiltration. Local delivery of a miR-21 mimic using ultrasound-targeted microbubbles into carotid plaques rescued the vulnerable plaque rupture phenotype. In the present study, we identify miR-21 as a key modulator of pathologic processes in advanced atherosclerosis. Targeted, lesion site-specific overexpression of miR-21 can stabilize vulnerable plaques.

Targeting Elastase for Molecular Imaging of Early Atherosclerotic Lesions.

OBJECTIVE: Neutrophils accumulate in early atherosclerotic lesions and promote lesion growth. In this study, we evaluated an elastase-specific near-infrared imaging agent for molecular imaging using hybrid fluorescence molecular tomography/x-ray computed tomography. APPROACH AND RESULTS: Murine neutrophils were isolated from bone marrow and incubated with the neutrophil-targeted near-infrared imaging agent Neutrophil Elastase 680 FAST for proof of principle experiments, verifying that the elastase-targeted fluorescent agent is specifically cleaved and activated by neutrophil content after lysis or cell stimulation. For in vivo experiments, low-density lipoprotein receptor-deficient mice were placed on a Western-type diet and imaged after 4, 8, and 12 weeks by fluorescence molecular tomography/x-ray computed tomography. Although this agent remains silent on injection, it produces fluorescent signal after cleavage by neutrophil elastase. After hybrid fluorescence molecular tomography/x-ray computed tomography imaging, mice were euthanized for whole-body cryosectioning and histological analyses. The in vivo fluorescent signal in the area of the aortic arch was highest after 4 weeks of high-fat diet feeding and decreased at 8 and 12 weeks. Ex vivo whole-body cryoslicing confirmed the fluorescent signal to locate to the aortic arch and to originate from the atherosclerotic arterial wall. Histological analysis demonstrated the presence of neutrophils in atherosclerotic lesions. CONCLUSIONS: This study provides evidence that elastase-targeted imaging can be used for in vivo detection of early atherosclerosis. This imaging approach may harbor potential in the clinical setting for earlier diagnosis and treatment of atherosclerosis.

Cathepsin S is associated with degradation of collagen I in abdominal aortic aneurysm.

BACKGROUND: Cathepsins have been described in the pathogenesis of abdominal aortic aneurysm (AAA), their exact role, especially in collagen degradation, is still unclear. The aim of the present study was therefore to analyse relevant cathepsins in human AAA tissue samples in relation to collagen I, III, and their degradation products. MATERIALS AND METHODS: Samples from 37 AAA patients obtained from elective open surgical repair and eight healthy non-aneurysmatic aortas from kidney donors were included. Expression of cathepsins B, D, K, L, S, cystatin C, collagen I and III, their degraded products C-Telopeptide of type 1 and 3 collagen (CTX-I, CTX-III), cellular markers for leukocytes (CD45), T cells (CD3), macrophage scavenger receptor-1 (MSR-1), synthetic, and contractile smooth muscle cells (SMCs) (smoothelin: SMTH, collagen I and III, myosin heavy chain: MHC, embryonic smooth muscle myosin heavy chain: SMemb) were determined at messenger RNA (mRNA) level, using SYBRGreen-based quantitative PCR and at protein level using enzyme-linked immunosorbent assay (ELISA). RESULTS: Expression of cathepsins B, D, L, and S at mRNA level was significantly elevated in AAA compared to control aorta (1.7-fold, p = 0.025; 2.5-fold, p = 0.002; 2.6-fold, p = 0.034; and 7.0-fold, p = 0.003). Expression of cathepsin S correlated significantly with leukocytes and macrophages (ρ = 0.398, p = 0.033 and ρ = 0.422, p = 0.020), synthetic SMCs were significantly associated with cathepsins B, D, and L (ρ = 0.522, p = 0.003; ρ = 0.431, p = 0.015 and ρ = 0.467, p = 0.008). At protein level, cathepsins B and S were elevated in AAA compared to controls (5.4-fold, p = 0.001 and 7.3-fold, p < 0.001). Significant correlations were observed between collagen I, its degraded product, and cathepsin S (r = -0.350, p = 0.034 and r = +0.504, p < 0.001). Expression of cathepsin B was associated with SMCs, expression of cathepsin S with inflammatory cells. CONCLUSIONS: Particularly cathepsin S was associated with the degradation product of collagen I and thus might be involved in the progression of AAA. Furthermore, cathepsin S correlated with inflammatory cells.

A short time interval between the neurologic index event and carotid endarterectomy is not a risk factor for carotid surgery.

OBJECTIVE: Current guidelines recommend that carotid endarterectomy (CEA) be performed as early as possible after the neurologic index event in patients with 50% to 99% carotid artery stenosis. However, recent registry data showed that patients treated ≤48 hours had a significantly increased perioperative risk. Therefore, the aim of this single-center study was to determine the effect of the time interval between the neurologic index event and CEA on the periprocedural complication rate at our institution. METHODS: Prospectively collected data for 401 CEAs performed between 2004 and 2014 for symptomatic carotid stenosis were analyzed. Patients were divided into four groups according to the interval between the last neurologic event and surgery: group I, 0 to 2 days; group II, 3 to 7 days; group III, 8 to 14 days; and group IV, 15 to 180 days. The primary end point was the combined rate of in-hospital stroke or mortality. Data were analyzed by way of χ2 tests and multivariable regression analysis. RESULTS: The patients (68% men) had a median age of 70 years (interquartile range, 63-76 years). The index events included transient ischemic attack in 43.4%, amaurosis fugax in 25.4%, and an ipsilateral stroke in 31.2%. CEA was performed using the eversion technique in 61.1% of patients, and 50.1% were treated under locoregional anesthesia. The perioperative combined stroke and mortality rate was 2.5% (10 of 401), representing a perioperative mortality rate of 1.0% and stroke rate of 1.5%. Overall, myocardial infarction, cranial nerve injuries, and postoperative bleeding occurred in 0.7%, 2.2%, and 1.7%, respectively. We detected no significant differences for the combined stroke and mortality rate by time interval: 3% in group I, 3% in group II, 2% in group III, and 2% in group IV. Multivariable regression analysis showed no significant effect of the time interval on the primary end point. CONCLUSIONS: The combined mortality and stroke rate was 2.5% and did not differ significantly between the four different time interval groups. CEA was safe in our cohort, even when performed as soon as possible after the index event.

CD8+ T Cells Regulate Monopoiesis and Circulating Ly6C-high Monocyte Levels in Atherosclerosis in Mice.

RATIONALE: Proinflammatory adaptive immune responses are recognized as major drivers of atherosclerotic lesion formation. Although CD8(+) T cells have recently been proposed as a proatherogenic cell subset, their full scope of actions remains to be elucidated. OBJECTIVE: We here addressed the contribution of CD8(+) T cells to monocyte trafficking in atherosclerosis. METHOD AND RESULTS: We observed that CD8(+) T cells express proinflammatory cytokines (interferon-γ, tumor necrosis factor-α, and interleukin-12) within atherosclerotic lesions and spleens of high-fat diet-fed low-density lipoprotein receptor-deficient (Ldlr(-/-)) mice. Antibody-mediated CD8(+) T-cell depletion in high-fat diet-fed Ldlr(-/-) mice decreased atherosclerotic plaque formation, associated with decreased macrophage accumulation within lesions. Despite a reduction in vascular chemokine (CC-motif) ligand 2 and chemokine (CXC-motif) ligand 1 expression, CD8(+) T-cell depletion did not directly affect monocyte recruitment to inflamed vessels. However, CD8(+) T-cell depletion decreased chemokine (CC-motif) ligand serum concentrations and circulating Ly6C(high) monocyte counts. We further evidenced that CD8(+) T-cell depletion decreased levels of mature monocytes and myeloid granulocyte-monocyte progenitors in the bone marrow and spleen of hypercholesterolemic mice, effects that were partially reproduced by interferon-γ neutralization, showing a role for interferon-γ. CONCLUSIONS: These data suggest that CD8(+) T cells promote atherosclerosis by controlling monopoiesis and circulating monocyte levels, which ultimately contributes to plaque macrophage burden without affecting direct monocyte recruitment, identifying this cell subset as a critical regulator of proatherogenic innate immune cell responses in atherosclerosis.

Thrombus Histology Suggests Cardioembolic Cause in Cryptogenic Stroke.

BACKGROUND AND PURPOSE: Ischemic stroke of undetermined cause is a major health issue because of its high frequency and clinical relevance. Histopathologic analysis of human thrombi, retrieved from stroke patients with large-vessel occlusion during mechanical thrombectomy, may provide information about underlying pathologies. This study examines the relationship between stroke causes and histological clot composition to identify specific patterns that might help to distinguish causes of cryptogenic stroke. METHODS: Thrombi of 145 consecutive stroke patients with large-vessel occlusion were collected during intracranial mechanical recanalization. The hematoxylin and eosin-stained specimens were quantitatively analyzed in terms of the relative fractions of the main constituents (red and white blood cells and fibrin/platelets). These data, along with additional clinical and interventional parameters, were compared for different stroke subtypes, as defined by the international Trial of Org 10172 in Acute Stroke Treatment criteria. RESULTS: The composition of thrombi from cardioembolic and noncardioembolic stroke patients differed significantly for all main thrombus components. Cardioembolic thrombi had higher proportions of fibrin/platelets (P=0.009), less erythrocytes (P=0.003), and more leucocytes (P=0.035) than noncardioembolic thrombi. Cryptogenic strokes showed strong overlap with cardioembolic strokes but not with noncardioembolic strokes, in terms of both thrombus histology and interventional and clinical outcome parameters. CONCLUSIONS: Quantitative evaluation of thrombus composition may help to distinguish between different stroke causes. Our findings support the notion that the majority of cryptogenic strokes are cardioembolic.

Deficiency of HIF1α in Antigen-Presenting Cells Aggravates Atherosclerosis and Type 1 T-Helper Cell Responses in Mice.

OBJECTIVE: Although immune responses drive the pathogenesis of atherosclerosis, mechanisms that control antigen-presenting cell (APC)-mediated immune activation in atherosclerosis remain elusive. We here investigated the function of hypoxia-inducible factor (HIF)-1α in APCs in atherosclerosis. APPROACH AND RESULTS: We found upregulated HIF1α expression in CD11c(+) APCs within atherosclerotic plaques of low-density lipoprotein receptor-deficient (Ldlr(-/-)) mice. Conditional deletion of Hif1a in CD11c(+) APCs in high-fat diet-fed Ldlr(-/-) mice accelerated atherosclerotic plaque formation and increased lesional T-cell infiltrates, revealing a protective role of this transcription factor. HIF1α directly controls Signal Transducers and Activators of Transcription 3 (Stat3), and a reduced STAT3 expression was found in HIF1α-deficient APCs and aortic tissue, together with an upregulated interleukin-12 expression and expansion of type 1 T-helper (Th1) cells. Overexpression of STAT3 in Hif1a-deficient APCs in bone marrow reversed enhanced atherosclerotic lesion formation and reduced Th1 cell expansion in chimeric Ldlr(-/-) mice. Notably, deletion of Hif1a in LysM(+) bone marrow cells in Ldlr(-/-) mice did not affect lesion formation or T-cell activation. In human atherosclerotic lesions, HIF1α, STAT3, and interleukin-12 protein were found to colocalize with APCs. CONCLUSIONS: Our findings identify HIF1α to antagonize APC activation and Th1 T cell polarization during atherogenesis in Ldlr(-/-) mice and to attenuate the progression of atherosclerosis. These data substantiate the critical role of APCs in controlling immune mechanisms that drive atherosclerotic lesion development.

Impact of sex and age on carotid plaque instability in asymptomatic patients-results from the Munich Vascular Biobank.

BACKGROUND: It is still a controversial issue whether carotid endarterectomy (CEA) for asymptomatic carotid stenosis is superior to best medical treatment. The aim of this study was therefore to analyze the impact of sex and age on carotid plaque instability in asymptomatic patients undergoing CEA. PATIENTS AND METHODS: Atherosclerotic plaques from 465 asymptomatic patients with high-grade carotid artery stenosis (2004 - 2013) at the Munich Vascular Biobank were analyzed. Ascertainment of lesion stability/instability was performed on formalin-fixed paraffin-embedded tissue samples using hematoxylin-eosin and elastic van Gieson staining. Unstable plaques were considered lesions with a fibrous cap < 200 µm overlaying lipid-rich atheroma. RESULTS: The average age of the patients was 69.3 ± 8.2 years. Independent of age, asymptomatic men had in total more frequently unstable plaques in contrast to women (41 % versus 52%, p = 0.042). No differences were found in plaque instability between age-related quartiles (< 65, 65- 69, 70 - 74, > 74 years) for female sex (p = 0.422). In men, a continuous increase in plaque instability with age was observed, without achieving statistical significance (p = 0.125). The greatest differences between male and female sex were found in the last quartile (> 74 years), without achieving statistical significance (p = 0.053). The chance of unstable carotid plaques in men was significantly higher than in women (OR = 1.562, p = 0.040). The probability of age-associated quartiles related to the first quartile demonstrated significant increase in plaque instability in the group of 65- to 69-year-old patients (OR 1.867, p = 0.024) and for patients older than 74 years (OR 1.740, p = 0.040). CONCLUSIONS: Asymptomatic men had in total more frequently unstable plaques in contrast to women. Thus, male sex seems to be an additional risk factor for ischemic stroke.

Carotid Plaque Morphology Is Significantly Associated With Sex, Age, and History of Neurological Symptoms.

BACKGROUND AND PURPOSE: The purpose of this study was to analyze the association between morphological characteristics of human carotid plaques and patient's sex, age, and history of neurological symptoms. METHODS: The study included 763 atherosclerotic plaques from patients treated surgically for carotid stenosis between 2004 and 2013. Histological analyses of carotid plaques were performed to assess the type of plaque (American Heart Association classification), the stability of the plaque, the extent of calcification, inflammation, and neovascularization, as well as the deposition of collagen and elastin. According to the scale of outcome measurement, logistic regression, ordinal regression, and multinomial regression analyses were applied. All results were adjusted for common risk factors of atherosclerosis. RESULTS: Male sex was associated with more cellularity (odds ratio [OR], 1.56; P=0.003), more inflammatory infiltrates (OR, 1.75; P<0.001), and more neovascularization (OR, 1.47; P=0.010), but less calcification (OR, 0.78; P=0.090). Symptomatic patients were more likely to have a lower amount of elastin (OR, 0.71; P=0.057). Higher age was associated with increased calcification (OR, 1.23; P=0.009). Unstable plaques were found more frequently in symptomatic patients (OR, 1.60; 95% confidence interval, 1.14-2.25; P=0.007). A multinomial regression model revealed that age, sex, and history of neurological symptoms were significantly associated with specific plaque types (P=0.009, P<0.001, and P=0.017, respectively). CONCLUSIONS: Plaque morphology differed between men and women and varied with age. Certain types of plaques (VI and VI/VII) as well as unstable plaques were significantly associated with a history of neurological symptoms. Thus, individual approaches (eg, in detection of plaque hemorrhage or thin fibrous caps) especially based on sex and age should be considered to identify patients at increased risk of stroke.

Biomechanics and gene expression in abdominal aortic aneurysm.

OBJECTIVE: The aim of the study was to detect inter-relations between the mechanical conditions and material properties of abdominal aortic aneurysm (AAA) wall and the underlying local gene expression of destabilizing inflammatory, proteolytic, and structural factors. METHODS: During open surgery, 51 tissue samples from 31 AAA patients were harvested. Gene expression of collagen types I and III, inflammatory factors CD45 and MSR1, proteolytic enzymes matrix metalloproteinases 2 and 9, and tissue inhibitor of matrix metalloproteinase 1 was analyzed by reverse transcription-polymerase chain reaction. Material properties of corresponding AAA tissue samples were assessed by cyclic sinusoidal and destructive testing. Local mechanical conditions of stress and strain were determined by advanced nonlinear finite element analysis based on patient-specific three-dimensional AAA models derived from preoperative computed tomography data. RESULTS: In the AAA wall, all parameters analyzed were significantly expressed at the messenger RNA level. With respect to mechanical properties of the aneurysmatic wall, expression of collagen III correlated with the stiffness parameter α (r = -0.348; P = .017), and matrix metalloprotease 2 correlated with the stiffness parameter ß and wall strength (r = -0.438 and -0.593; P = .005 and P < .001). Furthermore, significant relationships were observed between local AAA diameter and the expression of CD45, MSR1, and tissue inhibitor of matrix metalloproteinase 1 (r = 0.285, 0.551, 0.328; P < .05). However, we found no inter-relation of local calculated wall stresses and strains with gene expression. CONCLUSIONS: Our results show for the first time that gene expressions of destabilizing factors within AAA tissue might be correlated to geometric and mechanical properties of the AAA wall. However, we found no influence of local mechanical conditions on gene expression of these factors. Therefore, these preliminary results are still ambiguous.

POEMS syndrome, calciphylaxis and focal segmental glomerulosclerosis - VEGF as a possible link.

BACKGROUND: Polyneuropathy organomegaly endocrinopathy M-protein skin changes (POEMS) syndrome is a rare cause of polyneuropathy. Calciphylaxis, a severe disease leading to necrotic ulcers of the skin, is associated with POEMS syndrome and also with renal disease. This case report describes a patient with POEMS syndrome plus primary focal segmental glomerulosclerosis. CASE PRESENTATION: A 27-year-old Caucasian woman with chronic renal insufficiency due to focal segmental glomerulosclerosis and calciphylaxis presented to our institution with polyneuropathy and encephalopathy. An extensive diagnostic workup revealed POEMS syndrome. Serum concentrations of vascular endothelial growth factor (VEGF) were highly elevated, consistent with POEMS syndrome. CONCLUSION: To our knowledge, this is the first report of a patient with POEMS syndrome and primary focal segmental glomerulosclerosis. The combination of POEMS syndrome, calciphylaxis and primary focal segmental glomerulosclerosis may be coincidental, suggesting the need for additional studies to confirm or exclude this association. VEGF may be an important pathogenetic link, suggesting that treatment with antiangiogenic agents may improve patient outcomes.