Dipeptidyl peptidase 3 plasma levels predict cardiogenic shock and mortality in acute coronary syndromes.

BACKGROUND AND AIMS: Dipeptidyl peptidase 3 (DPP3) is a protease involved in the degradation of angiotensin II which disturbs peripheral blood pressure regulation and compromises left ventricular function. This study examined the relationship of circulating DPP3 (cDPP3) with cardiogenic shock (CS) and mortality in patients presenting with acute coronary syndromes (ACS). METHODS: Plasma cDPP3 levels were assessed at baseline and 12-24 h after presentation in patients with ACS prospectively enrolled into the multi-centre SPUM-ACS study (n = 4787). RESULTS: Circulating DPP3 levels were associated with in-hospital CS when accounting for established risk factors including the ORBI risk score [per log-2 increase, hazard ratio (HR) 1.38, 95% confidence interval (CI) 1.05-1.82, P = .021]. High cDPP3 was an independent predictor of mortality at 30 days (HR 1.87, 95% CI 1.36-2.58, P < .001) and at one year (HR 1.61, 95% CI 1.28-2.02, P < .001) after adjustment for established risk factors and the GRACE 2.0 score. Compared to values within the normal range, persistently elevated cDPP3 levels at 12-24 h were associated with 13.4-fold increased 30-day mortality risk (HR 13.42, 95% CI 4.86-37.09, P < .001) and 5.8-fold increased 1-year mortality risk (HR 5.79, 95% CI 2.70-12.42, P < .001). Results were consistent across various patient subgroups. CONCLUSIONS: This study identifies cDPP3 as a novel marker of CS and increased mortality in patients with ACS. Circulating DPP3 offers prognostic information beyond established risk factors and improves early risk assessment.

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.

Endothelial SIRT6 deficiency promotes arterial thrombosis in mice.

OBJECTIVE: Arterial thrombosis may be initiated by endothelial inflammation or denudation, activation of blood-borne elements or the coagulation system. Tissue factor (TF), a central trigger of the coagulation cascade, is regulated by the pro-inflammatory NF-κB-dependent pathways. Sirtuin 6 (SIRT6) is a nuclear member of the sirtuin family of NAD+-dependent deacetylases and is known to inhibit NF-κB signaling. Its constitutive deletion in mice shows early lethality with hypoglycemia and accelerated aging. Of note, the role of SIRT6 in arterial thrombosis remains unknown. Thus, we hypothesized that endothelial SIRT6 protects from arterial thrombosis by modulating inhibition of NF-κB-associated pathways. APPROACH AND RESULTS: Using a laser-induced carotid thrombosis model, in vivo arterial occlusion occurred 45% faster in 12-week-old male endothelial-specific Sirt6-/- mice as compared to Sirt6fl/fl controls (n ≥ 9 per group; p = 0.0012). Levels of procoagulant TF were increased in animals lacking endothelial SIRT6 as compared to control littermates. Similarly, in cultured human aortic endothelial cells, SIRT6 knockdown increased TF mRNA, protein and activity. Moreover, SIRT6 knockdown increased mRNA levels of NF-κB-associated genes tumor necrosis factor alpha (TNF-α), poly [ADP-ribose] polymerase 1 (PARP-1), vascular cell adhesion molecule 1 (VCAM-1), and cyclooxygenase-2 (COX-2); at the protein level, COX-2, VCAM-1, TNF-α, and cleaved PARP-1 remained increased after Sirt6 knockdown. CONCLUSIONS: Endothelium-specific Sirt6 deletion promotes arterial thrombosis in mice. In cultured human aortic endothelial cells, SIRT6 silencing enhances TF expression and activates pro-inflammatory pathways including TNF-α, cleaved PARP-1, VCAM-1 and COX-2. Hence, endogenous endothelial SIRT6 exerts a protective role in experimental arterial thrombosis.

Sex-specific evaluation and redevelopment of the GRACE score in non-ST-segment elevation acute coronary syndromes in populations from the UK and Switzerland: a multinational analysis with external cohort validation.

BACKGROUND: The Global Registry of Acute Coronary Events (GRACE) 2.0 score was developed and validated in predominantly male patient populations. We aimed to assess its sex-specific performance in non-ST-segment elevation acute coronary syndromes (NSTE-ACS) and to develop an improved score (GRACE 3.0) that accounts for sex differences in disease characteristics. METHODS: We evaluated the GRACE 2.0 score in 420 781 consecutive patients with NSTE-ACS in contemporary nationwide cohorts from the UK and Switzerland. Machine learning models to predict in-hospital mortality were informed by the GRACE variables and developed in sex-disaggregated data from 386 591 patients from England, Wales, and Northern Ireland (split into a training cohort of 309 083 [80·0%] patients and a validation cohort of 77 508 [20·0%] patients). External validation of the GRACE 3.0 score was done in 20 727 patients from Switzerland. FINDINGS: Between Jan 1, 2005, and Aug 27, 2020, 400 054 patients with NSTE-ACS in the UK and 20 727 patients with NSTE-ACS in Switzerland were included in the study. Discrimination of in-hospital death by the GRACE 2.0 score was good in male patients (area under the receiver operating characteristic curve [AUC] 0·86, 95% CI 0·86-0·86) and notably lower in female patients (0·82, 95% CI 0·81-0·82; p<0·0001). The GRACE 2.0 score underestimated in-hospital mortality risk in female patients, favouring their incorrect stratification to the low-to-intermediate risk group, for which the score does not indicate early invasive treatment. Accounting for sex differences, GRACE 3.0 showed superior discrimination and good calibration with an AUC of 0·91 (95% CI 0·89-0·92) in male patients and 0·87 (95% CI 0·84-0·89) in female patients in an external cohort validation. GRACE 3·0 led to a clinically relevant reclassification of female patients to the high-risk group. INTERPRETATION: The GRACE 2.0 score has limited discriminatory performance and underestimates in-hospital mortality in female patients with NSTE-ACS. The GRACE 3.0 score performs better in men and women and reduces sex inequalities in risk stratification. FUNDING: Swiss National Science Foundation, Swiss Heart Foundation, Lindenhof Foundation, Foundation for Cardiovascular Research, and Theodor-Ida-Herzog-Egli Foundation.

Among biomarkers of neutrophil activity, matrix metalloproteinases 8 independently predicts remission of metabolic syndrome.

BACKGROUND AND AIMS: Inflammation due to the excess of nutrient intake plays an important role in the pathophysiology of metabolic syndrome (MetS). Here, the potential influence of neutrophils and their degranulation markers on MetS improvement upon dietary and behavioral counselling, has been investigated. Specifically, we aimed at investigating their role as potential predictors of metabolic syndrome improvements. METHODS AND RESULTS: patients with MetS (n = 127) received behavioral and dietary recommendations before follow-up at 6 months. Serum levels of matrix metalloproteinases (MMP)8, MMP9, myeloperoxidase (MPO), tissue inhibitor of MMP (TIMP)-1, TIMP-2, TIMP-3 and resistin were tested at baseline. In the whole cohort, baseline levels of proinflammatory MMP8, MMP9 and MPO increased together with the number of MetS criteria. Seventy-three (57%) patients experienced a reduction in MetS-defining criteria at follow-up. With respect to those with no improvement, such individuals showed lower weight and waist circumference at enrolment, less frequent smoking habits, higher levels of triglycerides and lower circulating MMP8. At logistic regression analysis, baseline MMP8 showed negative predictive ability (odds ratio (OR) 0.979 [0.961-0.997]; p = 0.025) against MetS improvement. Such findings hold true even when included in the backward stepwise logistic regression model confirming MMP8 as an independent predictor (OR 0.970 [0.949-0.993]; p = 0.009). Receiver operating characteristic (ROC) curve confirmed the predictive ability of MMP8 combined in a model including baseline MetS criteria and waist circumference. Bootstrap resampling analysis internally validated our findings. CONCLUSION: Improvement of MetS is independently associated with baseline low MMP-8 levels, suggesting a pivotal role for inflammation in metabolic alteration.

Calcific aortic valve disease: from molecular and cellular mechanisms to medical therapy.

Calcific aortic valve disease (CAVD) is a highly prevalent condition that comprises a disease continuum, ranging from microscopic changes to profound fibro-calcific leaflet remodelling, culminating in aortic stenosis, heart failure, and ultimately premature death. Traditional risk factors, such as hypercholesterolaemia and (systolic) hypertension, are shared among atherosclerotic cardiovascular disease and CAVD, yet the molecular and cellular mechanisms differ markedly. Statin-induced low-density lipoprotein cholesterol lowering, a remedy highly effective for secondary prevention of atherosclerotic cardiovascular disease, consistently failed to impact CAVD progression or to improve patient outcomes. However, recently completed phase II trials provide hope that pharmaceutical tactics directed at other targets implicated in CAVD pathogenesis offer an avenue to alter the course of the disease non-invasively. Herein, we delineate key players of CAVD pathobiology, outline mechanisms that entail compromised endothelial barrier function, and promote lipid homing, immune-cell infiltration, and deranged phospho-calcium metabolism that collectively perpetuate a pro-inflammatory/pro-osteogenic milieu in which valvular interstitial cells increasingly adopt myofibro-/osteoblast-like properties, thereby fostering fibro-calcific leaflet remodelling and eventually resulting in left ventricular outflow obstruction. We provide a glimpse into the most promising targets on the horizon, including lipoprotein(a), mineral-binding matrix Gla protein, soluble guanylate cyclase, dipeptidyl peptidase-4 as well as candidates involved in regulating phospho-calcium metabolism and valvular angiotensin II synthesis and ultimately discuss their potential for a future therapy of this insidious disease.

Soluble lectin-like oxidized low-density lipoprotein receptor-1 predicts premature death in acute coronary syndromes.

AIMS: The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) and its shedding product [soluble LOX-1 (sLOX-1)] are implicated in atherosclerotic cardiovascular disease (ASCVD) pathogenesis. Herein, we examined the relationship of sLOX-1 with both fatal events and plaque progression in patients with acute coronary syndromes (ACS). METHODS AND RESULTS: Plasma sLOX-1 was assessed at baseline in ACS and chronic coronary syndrome (CCS) patients prospectively recruited in the multicentre SPUM-ACS study, with sex- and age-matched healthy subjects serving as additional controls (n = 2924). Compared with both CCS and controls, ACS patients showed markedly elevated sLOX-1 levels (median, 2.00 and 2.00 vs. 35.08 pg/mL; P < 0.0001) which were independently associated with increased mortality risk over 30-day [tertile (T)3: adjusted hazard ratio (HR), 3.11; 95% confidence interval (CI), 1.44-10.61; P = 0.0055] and 1-year intervals (T3: adjusted HR, 2.04; 95% CI, 1.19-3.92; P = 0.0098). Results remained consistent after adjustment for GRACE 2.0 (T3: adjusted HR, 1.86; 95% CI, 1.04-3.74; P = 0.0391) and were primarily driven by the pronounced relationship of sLOX-1 with cardiovascular mortality at 30 days (T3: adjusted HR, 3.81; 95% CI, 1.62-19.62; P = 0.0036) and at 1 year (T3: adjusted HR, 2.29; 95% CI, 1.19-5.34; P = 0.0148). In ACS patients undergoing serial intracoronary imaging and statin therapy, sLOX-1 dropped significantly in those with coronary plaque regression at 1 year (ΔsLOX-1: -4.64 ± 1.80; P = 0.0057), and showed a good discrimination for predicting plaque progression (area under the curve = 0.74; 95% CI, 0.59-0.86; P = 0.0031). CONCLUSION: Plasma sLOX-1 levels are increased during ACS and predict fatal events beyond traditional and emerging risk factors. Persistently high sLOX-1 associates with coronary plaque progression in patients with established ASCVD. CLINICAL TRIAL REGISTRATION: NCT01000701.

Microvesicles released from activated CD4+ T cells alter microvascular endothelial cell function.

BACKGROUND: Microvesicles are vesicles shed by plasma membranes following cell activation and apoptosis. The role of lymphocyte-derived microvesicles in endothelial function remains poorly understood. METHODS: CD4+ T cells isolated from peripheral blood of healthy human donors were stimulated using anti-CD3/anti-CD28-coated beads. Proteomic profiling of microvesicles was performed using linear discriminant analysis (LDA) from activated T cells (MV.Act) and nonactivated T cells (MV.NAct). In addition, data processing analysis was performed using MaxQUANT workflow. Differentially expressed proteins found in MV.Act or MV.NAct samples with identification frequency = 100%, which were selected by both LDA (p < .01) and MaxQUANT (p < .01) workflows, were defined as "high-confidence" differentially expressed proteins. Functional effects of MV.Act on human primary microvascular endothelial cells were analysed. RESULTS: T cells released large amounts of microvesicles upon stimulation. Proteomic profiling of microvesicles using LDA identified 2279 proteins (n = 2110 and n = 851 proteins in MV.Act and MV.NAct, respectively). Protein-protein interaction network models reconstructed from both differentially expressed proteins (n = 594; LDA p ≤ .01) and "high-confidence" differentially expressed proteins (n = 98; p ≤ .01) revealed that MV.Act were enriched with proteins related to immune responses, protein translation, cytoskeleton organisation and TNFα-induced apoptosis. For instance, MV.Act were highly enriched with IFN-γ, a key proinflammatory pathway related to effector CD4+ T cells. Endothelial cell incubation with MV.Act induced superoxide generation, apoptosis, endothelial wound healing impairment and endothelial monolayer barrier disruption. CONCLUSIONS: T cell receptor-mediated activation of CD4+ T cells stimulates the release of microvesicles enriched with proteins involved in immune responses, inflammation and apoptosis. T cell-derived microvesicles alter microvascular endothelial function and barrier permeability, potentially promoting tissue inflammation.

Resilience of the Internal Mammary Artery to Atherogenesis: Shifting From Risk to Resistance to Address Unmet Needs.

Fueled by the global surge in aging, atherosclerotic cardiovascular disease reached pandemic dimensions putting affected individuals at enhanced risk of myocardial infarction, stroke, and premature death. Atherosclerosis is a systemic disease driven by a wide spectrum of factors, including cholesterol, pressure, and disturbed flow. Although all arterial beds encounter a similar atherogenic milieu, the development of atheromatous lesions occurs discontinuously across the vascular system. Indeed, the internal mammary artery possesses unique biological properties that confer protection to intimal growth and atherosclerotic plaque formation, thus making it a conduit of choice for coronary artery bypass grafting. Its endothelium abundantly expresses nitric oxide synthase and shows accentuated nitric oxide release, while its vascular smooth muscle cells exhibit reduced tissue factor expression, high tPA (tissue-type plasminogen activator) production and blunted migration and proliferation, which may collectively mitigate intimal thickening and ultimately the evolution of atheromatous plaques. We aim here to provide insights into the anatomy, physiology, cellular, and molecular aspects of the internal mammary artery thereby elucidating its remarkable resistance to atherogenesis. We propose a change in perspective from risk to resilience to decipher mechanisms of atheroresistance and eventually identification of novel therapeutic targets presently not addressed by currently available remedies.

Cytokines as therapeutic targets for cardio- and cerebrovascular diseases.

Despite major advances in prevention and treatment, cardiac and cerebral atherothrombotic complications still account for substantial morbidity and mortality worldwide. In this context, inflammation is involved in the chronic process leading atherosclerotic plaque formation and its complications, as well as in the maladaptive response to acute ischemic events. For this reason, modulation of inflammation is nowadays seen as a promising therapeutic strategy to counteract the burden of cardio- and cerebrovascular disease. Being produced and recognized by both inflammatory and vascular cells, the complex network of cytokines holds key functions in the crosstalk of these two systems and orchestrates the progression of atherothrombosis. By binding to membrane receptors, these soluble mediators trigger specific intracellular signaling pathways eventually leading to the activation of transcription factors and a deep modulation of cell function. Both stimulatory and inhibitory cytokines have been described and progressively reported as markers of disease or interesting therapeutic targets in the cardiovascular field. Nevertheless, cytokine inhibition is burdened by harmful side effects that will most likely prevent its chronic use in favor of acute administrations in well-selected subjects at high risk. Here, we summarize the current state of knowledge regarding the modulatory role of cytokines on atherosclerosis, myocardial infarction, and stroke. Then, we discuss evidence from clinical trials specifically targeting cytokines and the potential implication of these advances into daily clinical practice.

TNF-α antagonism rescues the effect of ageing on stroke: Perspectives for targeting inflamm-ageing.

AIMS: Epidemiologic evidence links ischemic stroke to age, yet the mechanisms that underlie the specific and independent effects of age on stroke remain elusive, impeding the development of targeted treatments. This study tested the hypothesis that age directly aggravates stroke outcomes and proposes inflamm-aging as a mediator and potential therapeutic target. METHODS: 3 months- (young) and 18-20 months-old (old) mice underwent transient middle cerebral artery occlusion (tMCAO) for 30 minutes followed by 48 hours of reperfusion. Old animals received weekly treatment with the TNF-α neutralizing antibody adalimumab over 4 weeks before tMCAO in a separate set of experiments. Plasma levels of TNF- α were assessed in patients with ischemic stroke and correlated with age and outcome. RESULTS: Old mice displayed larger stroke size than young ones with increased neuromotor deficit. Immunohistochemical analysis revealed impairment of the blood-brain barrier in old mice, i.e. increased post-stroke degradation of endothelial tight junctions and expression of tight junctions-digesting and neurotoxic matrix metalloproteinases. At baseline, old animals showed a broad modulation of several circulating inflammatory mediators. TNF-α displayed the highest increase in old animals and its inhibition restored the volume of stroke, neuromotor performance, and survival rates of old mice to the levels observed in young ones. Patients with ischemic stroke showed increased TNF-α plasma levels which correlated with worsened short-term neurological outcome as well as with age. CONCLUSIONS: This study identifies TNF-α as a causative contributor to the deleterious effect of aging on stroke and points to inflamm-aging as a mechanism of age-related worsening of stroke outcomes and potential therapeutic target in this context. Thus, this work provides a basis for tailoring novel stroke therapies for the particularly vulnerable elderly population.

Inflamm-ageing: the role of inflammation in age-dependent cardiovascular disease.

The ongoing worldwide increase in life expectancy portends a rising prevalence of age-related cardiovascular (CV) diseases in the coming decades that demands a deeper understanding of their molecular mechanisms. Inflammation has recently emerged as an important contributor for CV disease development. Indeed, a state of chronic sterile low-grade inflammation characterizes older organisms (also known as inflamm-ageing) and participates pivotally in the development of frailty, disability, and most chronic degenerative diseases including age-related CV and cerebrovascular afflictions. Due to chronic activation of inflammasomes and to reduced endogenous anti-inflammatory mechanisms, inflamm-ageing contributes to the activation of leucocytes, endothelial, and vascular smooth muscle cells, thus accelerating vascular ageing and atherosclerosis. Furthermore, inflamm-ageing promotes the development of catastrophic athero-thrombotic complications by enhancing platelet reactivity and predisposing to plaque rupture and erosion. Thus, inflamm-ageing and its contributors or molecular mediators might furnish targets for novel therapeutic strategies that could promote healthy ageing and conserve resources for health care systems worldwide. Here, we discuss recent findings in the pathophysiology of inflamm-ageing, the impact of these processes on the development of age-related CV diseases, results from clinical trials targeting its components and the potential implementation of these advances into daily clinical practice.

Endothelial SIRT6 blunts stroke size and neurological deficit by preserving blood-brain barrier integrity: a translational study.

AIMS: Aging is an established risk factor for stroke; genes regulating longevity are implicated in the pathogenesis of ischaemic stroke where to date, therapeutic options remain limited. The blood-brain barrier (BBB) is crucially involved in ischaemia/reperfusion (I/R) brain injury thus representing an attractive target for developing novel therapeutic agents. Given the role of endothelial cells in the BBB, we hypothesized that the endothelial-specific expression of the recently described longevity gene SIRT6 may exhibit protective properties in stroke. METHODS AND RESULTS: SIRT6 endothelial expression was reduced following stroke. Endothelial-specific Sirt6 knockout (eSirt6-/-) mice, as well as animals in which Sirt6 overexpression was post-ischaemically induced, underwent transient middle cerebral artery occlusion (tMCAO). eSirt6-/- animals displayed increased infarct volumes, mortality, and neurological deficit after tMCAO, as compared to control littermates. Conversely, post-ischaemic Sirt6 overexpression decreased infarct size and neurological deficit. Analysis of ischaemic brain sections revealed increased BBB damage and endothelial expression of cleaved caspase-3 in eSIRT6-/- mice as compared to controls. In primary human brain microvascular endothelial cells (HBMVECs), hypoxia/reoxygenation (H/R) reduced SIRT6 expression and SIRT6 silencing impaired the barrier function (transendothelial resistance) similar to what was observed in mice exposed to I/R. Further, SIRT6-silenced HBMVECs exposed to H/R showed reduced viability, increased cleaved caspase-3 expression and reduced activation of the survival pathway Akt. In ischaemic stroke patients, SIRT6 expression was higher in those with short-term neurological improvement as assessed by NIHSS scale and correlated with stroke outcome. CONCLUSION: Endothelial SIRT6 exerts a protective role in ischaemic stroke by blunting I/R-mediated BBB damage and thus, it may represent an interesting novel therapeutic target to be explored in future clinical investigation.

Apold1 deficiency associates with increased arterial thrombosis in vivo.

BACKGROUND: Endothelial cells regulate the formation of blood clots; thus, genes selectively expressed in these cells could primarily determine thrombus formation. Apold1 (apolipoprotein L domain containing 1) is a gene expressed by endothelial cells; whether Apold1 directly contributes to arterial thrombosis has not yet been investigated. Here, we assessed the effect of Apold1 deletion on arterial thrombus formation using an in vivo model of carotid thrombosis induced by photochemical injury. MATERIAL AND METHODS: Apold1 knockout (Apold1-/- ) mice and wild-type (WT) littermates underwent carotid thrombosis induced by photochemical injury, and time to occlusion was recorded. Tissue factor (TF) activity and activation of mitogen-activated protein kinases (MAPKs) and phosphatidyl-inositol-3 kinase (PI3K)/Akt pathways were analysed by colorimetric assay and Western blotting in both Apold1-/- and WT mice. Finally, platelet reactivity was assessed using light transmission aggregometry. RESULTS: After photochemical injury, Apold1-/- mice exhibited shorter time to occlusion as compared to WT mice. Moreover, TF activity was increased in carotid arteries of Apold1-/- when compared to WT mice. Underlying mechanistic markers such as TF mRNA and MAPKs activation were unaffected in Apold1-/- mice. In contrast, phosphorylation of Akt was reduced in Apold1-/- as compared to WT mice. Additionally, Apold1-/- mice displayed increased platelet reactivity to stimulation with collagen compared with WT animals. CONCLUSIONS: Deficiency of Apold1 results in a prothrombotic phenotype, accompanied by increased vascular TF activity, decreased PI3K/Akt activation and increased platelet reactivity. These findings suggest Apold1 as an interesting new therapeutic target in the context of arterial thrombosis.

Glycoprotein Ib clustering in platelets can be inhibited by α-linolenic acid as revealed by cryo-electron tomography.

Platelet adhesion to the sub-endothelial matrix and damaged endothelium occurs through a multi-step process mediated in the initial phase by glycoprotein Ib binding to von Willebrand factor (vWF), which leads to the subsequent formation of a platelet plug. The plant-derived ω-3 fatty acid α-linolenic acid is an abundant alternative to fish-derived n-3 fatty acids and has anti-inflammatory and antithrombotic properties. In this study, we investigated the impact of α-linolenic acid on human platelet binding to vWF under high-shear flow conditions (mimicking blood flow in stenosed arteries). Pre-incubation of fresh human blood from healthy donors with α-linolenic acid at dietary relevant concentrations reduced platelet binding and rolling on vWF-coated microchannels at a shear rate of 100 dyn/cm2 Depletion of membrane cholesterol by incubation of platelet-rich plasma with methyl-ß cyclodextrin abrogated platelet rolling on vWF. Analysis of glycoprotein Ib by applying cryo-electron tomography to intact platelets revealed local clusters of glycoprotein Ib complexes upon exposure to shear force: the formation of these complexes could be prevented by treatment with α-linolenic acid. This study provides novel findings on the rapid local rearrangement of glycoprotein Ib complexes in response to high-shear flow and highlights the mechanism of in vitro inhibition of platelet binding to and rolling on vWF by α-linolenic acid.

Murine tissue factor disulfide mutation causes a bleeding phenotype with sex specific organ pathology and lethality.

Tissue factor is highly expressed in sub-endothelial tissue. The extracellular allosteric disulfide bond Cys186-Cys209 of human tissue factor shows high evolutionary conservation and in vitro evidence suggests that it significantly contributes to tissue factor procoagulant activity. To investigate the role of this allosteric disulfide bond in vivo, we generated a C213G mutant tissue factor mouse by replacing Cys213 of the corresponding disulfide Cys190-Cys213 in murine tissue factor. A bleeding phenotype was prominent in homozygous C213G tissue factor mice. Pre-natal lethality of 1/3rd of homozygous offspring was observed between E9.5 and E14.5 associated with placental hemorrhages. After birth, homozygous mice suffered from bleedings in different organs and reduced survival. Homozygous C213G tissue factor male mice showed higher incidence of lung bleedings and lower survival rates than females. In both sexes, C213G mutation evoked a reduced protein expression (about 10-fold) and severely reduced pro-coagulant activity (about 1000-fold). Protein glycosylation was impaired and cell membrane exposure decreased in macrophages in vivo. Single housing of homozygous C213G tissue factor males reduced the occurrence of severe bleeding and significantly improved survival, suggesting that inter-male aggressiveness might significantly account for the sex differences. These experiments show that the tissue factor allosteric disulfide bond is of crucial importance for normal in vivo expression, post-translational processing and activity of murine tissue factor. Although C213G tissue factor mice do not display the severe embryonic lethality of tissue factor knock-out mice, their postnatal bleeding phenotype emphasizes the importance of fully functional tissue factor for hemostasis.

Obesity-induced activation of JunD promotes myocardial lipid accumulation and metabolic cardiomyopathy.

AIMS: Metabolic cardiomyopathy (MC)-characterized by intra-myocardial triglyceride (TG) accumulation and lipotoxic damage-is an emerging cause of heart failure in obese patients. Yet, its mechanisms remain poorly understood. The Activator Protein 1 (AP-1) member JunD was recently identified as a key modulator of hepatic lipid metabolism in obese mice. The present study investigates the role of JunD in obesity-induced MC. METHODS AND RESULTS: JunD transcriptional activity was increased in hearts from diet-induced obese (DIO) mice and was associated with myocardial TG accumulation and left ventricular (LV) dysfunction. Obese mice lacking JunD were protected against MC. In DIO hearts, JunD directly binds PPARγ promoter thus enabling transcription of genes involved in TG synthesis, uptake, hydrolysis, and storage (i.e. Fas, Cd36, Lpl, Plin5). Cardiac-specific overexpression of JunD in lean mice led to PPARγ activation, cardiac steatosis, and dysfunction, thereby mimicking the MC phenotype. In DIO hearts as well as in neonatal rat ventricular myocytes exposed to palmitic acid, Ago2 immunoprecipitation, and luciferase assays revealed JunD as a direct target of miR-494-3p. Indeed, miR-494-3p was down-regulated in hearts from obese mice, while its overexpression prevented lipotoxic damage by suppressing JunD/PPARγ signalling. JunD and miR-494-3p were also dysregulated in myocardial specimens from obese patients as compared with non-obese controls, and correlated with myocardial TG content, expression of PPARγ-dependent genes, and echocardiographic indices of LV dysfunction. CONCLUSION: miR-494-3p/JunD is a novel molecular axis involved in obesity-related MC. These results pave the way for approaches to prevent or treat LV dysfunction in obese patients.

Recombinant Tissue Plasminogen Activator (r-tPA) Induces In-Vitro Human Neutrophil Migration via Low Density Lipoprotein Receptor-Related Protein 1 (LRP-1).

Thrombolysis is the gold standard treatment for acute ischemic stroke. Besides its fibrinolytic role, recombinant tissue plasminogen activator (r-tPA) holds several non-fibrinolytic functions. Here, we investigated the potential role of r-tPA on human primary neutrophil migration in vitro. By means of modified Boyden chamber migration assay and checkerboard analysis we showed a dose-dependent chemotactic effect of r-TPA with a maximum effect reached by 0.03 mg/mL (0.003-1 mg/mL). Pre-incubation with MAP kinases inhibitors allowed the identification of PI3K/Akt, but not ERK1/2 as the intracellular pathway mediating the observed effects. Furthermore, by means of real-time PCR, immunocytochemistry and cytofluorimetry we demonstrated that the r-tPA receptor low density lipoprotein receptor-related protein 1 (LRP-1) is synthetized and expressed by neutrophils in response to r-tPA and TNF-α. Inhibition of LRP-1 by receptor-associated protein (RAP), prevented r-tPA-mediated F-actin polymerization, migration and signal through Akt but not ERK1/2. Lastly, also neutrophil degranulation in response to r-tPA seems to be mediated by LRP-1 under adhesion conditions. In conclusion, we show that r-tPA induces neutrophil chemotaxis through LRP-1/Akt pathway. Blunting r-tPA-mediated neutrophil activation might be beneficial as an adjuvant therapy to thrombolysis in this setting.

AP-1 (Activated Protein-1) Transcription Factor JunD Regulates Ischemia/Reperfusion Brain Damage via IL-1ß (Interleukin-1ß).

Background and Purpose- Inflammation is a major pathogenic component of ischemia/reperfusion brain injury, and as such, interventions aimed at inhibiting inflammatory mediators promise to be effective strategies in stroke therapy. JunD-a member of the AP-1 (activated protein-1) family of transcription factors-was recently shown to regulate inflammation by targeting IL (interleukin)-1ß synthesis and macrophage activation. The purpose of the present study was to assess the role of JunD in ischemia/reperfusion-induced brain injury. Methods- WT (wild type) mice randomly treated with either JunD or scramble (control) siRNA were subjected to 45 minutes of transient middle cerebral artery occlusion followed by 24 hours of reperfusion. Stroke size, neurological deficit, plasma/brain cytokines, and oxidative stress determined by 4-hydroxynonenal immunofluorescence staining were evaluated 24 hours after reperfusion. Additionally, the role of IL-1ß was investigated by treating JunD siRNA mice with an anti-IL-1ß monoclonal antibody on reperfusion. Finally, JunD expression was assessed in peripheral blood monocytes isolated from patients with acute ischemic stroke. Results- In vivo JunD knockdown resulted in increased stroke size, reduced neurological function, and increased systemic inflammation, as confirmed by higher neutrophil count and lymphopenia. Brain tissue IL-1ß levels were augmented in JunD siRNA mice as compared with scramble siRNA, whereas no difference was detected in IL-6, TNF-α (tumor necrosis factor-α), and 4-hydroxynonenal levels. The deleterious effects of silencing of JunD were rescued by treating mice with an anti-IL-1ß antibody. In addition, JunD expression was decreased in peripheral blood monocytes of patients with acute ischemic stroke at 6 and 24 hours after onset of stroke symptoms compared with sex- and age-matched healthy controls. Conclusions- JunD blunts ischemia/reperfusion-induced brain injury via suppression of IL-1ß.

Ischemic stroke across sexes: What is the status quo?

Stroke prevalence is expected to increase in the next decades due to the aging of the Western population. Ischemic stroke (IS) shows an age- and sex-dependent distribution in which men represent the most affected population within 65 years of age, being passed by post-menopausal women in older age groups. Furthermore, a sexual dimorphism concerning risk factors, presentation and treatment of IS has been widely recognized. In order to address these phenomena, a number of issue have been raised involving both socio-economical and biological factors. The latter can be either dependent on sex hormones or due to intrinsic factors. Although women have poorer outcomes and are more likely to die after a cerebrovascular event, they are still underrepresented in clinical trials and this is mirrored by the lack of sex-tailored therapies. A greater effort is needed in the future to ensure improved treatment and quality of life to both sexes.