Omega-3 Fatty Acids and Markers of Thrombosis in Patients with Atrial Fibrillation

Omega-3 fatty acids (n-3 FAs) are associated with a lower risk of ischemic stroke in patients with atrial fibrillation (AF). Antithrombotic mechanisms may in part explain this observation. Therefore, we examined the association of n-3 FAs with D-dimer and beta-thromboglobulin (BTG), markers for activated coagulation and platelets, respectively. The n-3 FAs eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), docosapentaenoic acid (DPA) and alpha-linolenic acid (ALA) were determined via gas chromatography in the whole blood of 2373 patients with AF from the Swiss Atrial Fibrillation cohort study (ClinicalTrials.gov Identifier: NCT02105844). In a cross-sectional analysis, we examined the association of total n-3 FAs (EPA + DHA + DPA + ALA) and the association of individual fatty acids with D-dimer in patients with detectable D-dimer values (n = 1096) as well as with BTG (n = 2371) using multiple linear regression models adjusted for confounders. Median D-dimer and BTG levels were 0.340 ug/mL and 448 ng/mL, respectively. Higher total n-3 FAs correlated with lower D-dimer levels (coefficient 0.94, 95% confidence interval (Cl) 0.90-0.98, p = 0.004) and lower BTG levels (coefficient 0.97, Cl 0.95-0.99, p = 0.003). Likewise, the individual n-3 FAs EPA, DHA, DPA and ALA showed an inverse association with D-dimer. Higher levels of DHA, DPA and ALA correlated with lower BTG levels, whereas EPA showed a positive association with BTG. In patients with AF, higher levels of n-3 FAs were associated with lower levels of D-dimer and BTG, markers for activated coagulation and platelets, respectively. These findings suggest that n-3 FAs may exert antithrombotic properties in patients with AF.

Case report of long-term postural tachycardia syndrome in a patient after messenger RNA coronavirus disease-19 vaccination with mRNA-1273

Background

Postural tachycardia syndrome (POTS) is characterized by orthostatic intolerance and heart rate increase in an upright position without orthostatic hypotension. It has been described after coronavirus disease-19 (COVID-19) as well as after COVID-19 vaccination.

Case summary

A 54-year-old female patient presented with a 9-months history of severe orthostatic intolerance since COVID-19 vaccination with messenger RNA (mRNA)-1273 (Spikevax, Moderna). Except for diet-controlled coeliac disease, the patient was healthy, had no allergies, and did not take regular medication. Tilt table testing revealed a significant heart rate increase to 168 bpm without orthostatic hypotension accompanied by light-headedness, nausea, and syncope, findings consistent with POTS. Potential underlying causes including anaemia, thyroid dysfunction, adrenal insufficiency, pheochromocytoma, (auto)-immune disease, chronic inflammation as well as neurological causes were ruled out. Echocardiography and cardiac stress magnetic resonance imaging (MRI) did not detect structural or functional heart disease or myocardial ischaemia. Forty-eight-hour-electrocardiogram (ECG) showed no tachycardias other than sinus tachycardia. Finally, genomic analysis did not detect an inherited arrhythmia syndrome. Serologic analysis revealed adequate immune response to mRNA-1273 vaccination without signs of previous severe acute respiratory syndrome-coronavirus-2 infection. While ivabradine was not tolerated and metoprolol extended release only slightly improved symptoms, physical exercise reduced orthostatic intolerance moderately. At a 5-months follow-up, the patient remained dependant on assistance for activities of daily living.

Discussion

The temporal association of POTS with the COVID-19 vaccination in a previously healthy patient and the lack of evidence of an alternative aetiology suggests COVID-19 vaccination is the potential cause of POTS in this patient. To our knowledge, this is the first case reporting severe, long-term, and treatment-refractory POTS following COVID-19 vaccination with mRNA1273.

Prevention of M2 polarization and temporal limitation of differentiation in monocytes by extracellular ATP

BACKGROUND

Elevated levels of extracellular adenosine triphosphate (ATP) modulate immunologic pathways and are considered to be a danger signal in inflammation, lung fibrosis and cancer. Macrophages can be classified into two main types: M1 macrophages are classically activated, pro-inflammatory macrophages, whereas M2 macrophages are alternatively activated, pro-fibrotic macrophages. In this study, we examined the effect of ATP on differentiation of native human monocytes into these macrophage subtypes. We characterized M1 and M2 like macrophages by their release of Interleukin-1beta (IL-1β) and Chemokine (C-C motif) ligand 18 (CCL18), respectively.

RESULTS

Monocytes were stimulated with ATP or the P2X7 receptor agonist Benzoylbenzoyl-ATP (Bz-ATP), and the production of various cytokines was analyzed, with a particular focus on CCL18 and IL-1β, along with the expression of different purinergic receptors. Over a 72 h period of cell culture, monocytes spontaneously differentiated to M2 like macrophages, as indicated by an increased release of CCL18. Immediate stimulation of monocytes with ATP resulted in a dose-dependent reduction in CCL18 release, but had no effect on the concentration of IL-1β. In contrast, delayed stimulation with ATP had no effect on either CCL18 or IL-1β release. Similar results were observed in a model of inflammation using lipopolysaccharide-stimulated human monocytes. Stimulation with the P2X7 receptor agonist Bz-ATP mimicked the effect of ATP on M2-macrophage differentiation, indicating that P2X7 is involved in ATP-induced inhibition of CCL18 release. Indeed, P2X7 was downregulated during spontaneous M2 differentiation, which may partially explain the ineffectiveness of late ATP stimulation of monocytes. However, pre-incubation of monocytes with PPADS, Suramin (unselective P2X- and P2Y-receptor blockers) and KN62 (P2X7-antagonist) failed to reverse the reduction of CCL18 by ATP.

CONCLUSIONS

ATP prevents spontaneous differentiation of monocytes into M2-like macrophages in a dose- and time-dependent manner. These effects were not mediated by P2X and P2Y receptors.

Omega-3 Fatty Acids and Heart Rhythm, Rate, and Variability in Atrial Fibrillation

Background Previous randomized control trials showed mixed results concerning the effect of omega-3 fatty acids (n-3 FAs) on atrial fibrillation (AF). The associations of n-3 FA blood levels with heart rhythm in patients with established AF are unknown. The goal of this study was to assess the associations of total and individual n-3 FA blood levels with AF type (paroxysmal versus nonparoxysmal), heart rate (HR), and HR variability in patients with AF. Methods and Results Total n-3 FAs, eicosapentaenoic acid, docosahexaenoic acid, docosapentaenoic acid, and alpha-linolenic acid blood levels were determined in 1969 patients with known AF from the SWISS-AF (Swiss Atrial Fibrillation cohort). Individual and total n-3 FAs were correlated with type of AF, HR, and HR variability using standard logistic and linear regression, adjusted for potential confounders. Only a mild association with nonparoxysmal AF was found with total n-3 FA (odds ratio [OR], 0.97 [95% CI, 0.89-1.05]) and docosahexaenoic acid (OR, 0.93 [95% CI, 0.82-1.06]), whereas other individual n-3 FAs showed no association with nonparoxysmal AF. Higher total n-3 FAs (estimate 0.99 [95% CI, 0.98-1.00]) and higher docosahexaenoic acid (0.99 [95% CI, 0.97-1.00]) tended to be associated with slower HR in multivariate analysis. Docosapentaenoic acid was associated with a lower HR variability triangular index (0.94 [95% CI, 0.89-0.99]). Conclusions We found no strong evidence for an association of n-3 FA blood levels with AF type, but higher total n-3 FA levels and docosahexaenoic acid might correlate with lower HR, and docosapentaenoic acid with a lower HR variability triangular index.

Blood Omega-3 Fatty Acids Are Inversely Associated With Albumin-Creatinine Ratio in Young and Healthy Adults (The Omega-Kid Study)

Background: Omega-3 fatty acids are associated with a lower risk of cardiovascular disease (CVD) and with beneficial effects on CV risk factors. The albumin-creatinine ratio (ACR) is a risk factor for CVD, all-cause mortality and accelerated glomerular filtration rate (GFR) decline in the general population. We aimed to investigate the association between n-3 PUFAS and ACR in heathy individuals with preserved GFR. Design and Methods: The present cross-sectional analysis is part of the GAPP study, a population-based cohort of healthy adults aged 25-41 years. Individuals with known CVD, diabetes, or a BMI >35 kg/m² were excluded. eGFR was calculated according to the combined Creatinine/Cystatin C CKD-EPI formula. ACR was obtained from a fasting morning urine sample. The Omega-3 Index (relative amount of EPA and DHA of total fatty acids in %) was obtained from whole blood aliquots. Results: Overall, 2001 participants (median age 37 years IQR 31; 40, 53% female) were included in this analysis. Median Omega-3 Index was 4.59 (IQR 4.06; 5.25) and median eGFR 111 ml/min/1.73 m² (IQR 103; 118). Median ACR was 0.14 mg/mmol (IQR 0; 0.43). We found a significant inverse association of the Omega-3 Index with ACR (ratio 0.84, 95%CI 0.73-0.96; p = 0.011) which remained after comprehensive adjustment (ratio 0.86, 95%CI 0.74-1.00; p = 0.048). No association of the Omega-3 Index with eGFR was found. The adjusted difference in eGFR per 1-unit increase in Omega3-Index was -0.21 (95%CI -0.76; 0.35; p = 0.47). Conclusions: A higher Omega-3 Index was significantly associated with lower ACR in this young and healthy population with preserved eGFR. Omega-3 fatty acids may exhibit cardio- and nephroprotective effects in healthy individuals through modulation of ACR.

[For Once Not Corona Virus - an Uncommon Cause of Fever and Hepatitis]

For Once Not Corona Virus - an Uncommon Cause of Fever and Hepatitis Abstract. Our case reports acute Q fever as uncommon cause of fever, typically accompanied by pneumonia and/or hepatitis. It is caused by Coxiella burnetii, a bacterium which is generally hosted by live stock and affects humans by inhaling aerosols of the animals' excrements. If detected, it may be treated effectively. It should be considered in patients living in a typical environment or with a typical history. The route of our patient's infection remains unclear since he plausibly denied contact with any animals.

Deleterious role of endothelial lectin-like oxidized low-density lipoprotein receptor-1 in ischaemia/reperfusion cerebral injury

Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is implicated in cardiovascular disease by modulating apoptosis and oxidative stress. We hypothesized that LOX-1 may be involved in pathophysiology of stroke by mediating ischaemia/reperfusion (I/R)-dependent cell death. Transient middle cerebral artery occlusion (tMCAO) was performed in wild-type (WT) mice, endothelial-specific LOX-1 transgenic mice (eLOX-1TG) and WT animals treated with LOX-1 silencing RNA (siRNA). In WT mice exposed to tMCAO, LOX-1 expression and function were increased in the MCA. Compared to WT animals, eLOX-1TG mice displayed increased stroke volumes and worsened outcome after I/R. Conversely, LOX-1-silencing decreased both stroke volume and neurological impairment. Similarly, in HBMVECs, hypoxia/reoxygenation increased LOX-1 expression, while LOX-1 overexpressing cells showed increased death following hypoxia reoxygenation. Increased caspase-3 activation was observed following LOX-1 overexpression both in vivo and in vitro, thus representing a likely mediator. Finally, monocytes from ischaemic stroke patients exhibited increased LOX-1 expression which also correlated with disease severity. Our data unequivocally demonstrate a key role for LOX-1 in determining outcome following I/R brain damage. Our findings could be corroborated in human brain endothelial cells and monocytes from patients, underscoring their translational relevance and suggesting siRNA-mediated LOX-1 knockdown as a novel therapeutic strategy for stroke patients.

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

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)-1β 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-1β was investigated by treating JunD siRNA mice with an anti-IL-1β 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-1β 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-1β 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-1β.

P1898Prevalence and risk of DOACs inappropriate dosing in atrial fibrillation. An analysis of the Swiss-AF and BEAT-AF registries

Background

Direct oral anticoagulants (DOACs) have a similar efficacy in terms of stroke and mortality reduction as compared to Vitamin K-Antagonists (VKAs) and improved safety with regards to intracranial haemorrhage in patients with non-valvular atrial fibrillation (AF). Dose of DOACs needs to be adjusted according to age, weight, renal function and concomitant medication. Yet, off-label dosages have been reported in 11 - 45% of patients (on average 20%).

Purpose

To assess the prevalence of inappropriate DOAC-dosing according to the official prescribing information in two large prospective Swiss AF cohorts (Swiss-AF and BEAT-AF) and to evaluate its correlation with adverse clinical outcomes.

Methods

All 3267 patients taking oral anticoagulants were stratified at baseline as receiving DOACs (adequately dosed, under- or overdosed) or VKAs. Appropriateness of DOAC dosing was assessed based on age (≥80 years), weight (≤60kg) and renal function (serum creatinine ≥133μmol/l [apixaban]; creatinine clearence ≤50ml/min [all other DOACs]). Clinical outcomes were collected during a median follow-up of 2.96 years. Major adverse clinical events (MACE) consisted of a combination of myocardial infarction, cardiac death, ischemic stroke and systemic embolism. Safety was assessed by occurrence of any bleeding event.

Results

1902 patients (58%) were on VKAs and 1365 on DOACs (42%). In the DOAC group, 1149 patients received a dose consistent with drug labelling (84%), 133 (10%) received an inappropriately high and 83 (6%) an inappropriately low dose. Overdosed patients were older than those adequately treated and more likely female, had a lower BMI and a higher CHA2DS2-VASc score (4 vs. 3 points) (p<0.001 for all). Underdosed patients were more likely to have concomitant antiplatelet therapy (p<0.001). Both off-label groups were more likely to have a history of coronary artery disease, heart failure and chronic kidney disease (p<0.001). Kaplan-Meier cumulative incidence rates for the first occurrence of MACE or bleedings are provided in Figure 1. Overdosed patients had an almost two-fold higher risk of bleeding (9.0 vs. 5.0 events per 100 patient-years compared to correctly dosed DOACs and to VKAs) and a higher rate of MACE (5.1 vs. 2.3 events per 100 patient years compared to correctly dosed DOACs and 5.1 vs. 3.4 compared to VKAs). Underdosing did not seem to be associated with a relevant increase in ischemic or bleeding events as compared to correctly dosed DOACs and VKAs (see Figure 1).

Figure 1. Kaplan-Meier incidence curves

Conclusion

Inadequate DOACs dosing was found in 1 in 6 patients and correlated with a higher burden of comorbidities at baseline. Underdosing correlated with concomitant antiplatelet therapy. Overdosing was associated with adverse clinical outcome for ischemic and bleeding events.

Antithrombotic therapy and major adverse limb events in patients with chronic lower extremity arterial disease: systematic review and meta-analysis from the European Society of Cardiology Working Group on Cardiovascular Pharmacotherapy in Collaboration with the European Society of Cardiology Working Group on Aorta and Peripheral Vascular Diseases

Aims

The role and selection of antithrombotic therapy to improve limb outcomes in chronic lower extremity artery disease (LEAD) is still debated. We conducted a meta-analysis to examine the efficacy and safety of antithrombotic and more intense antithrombotic therapy on limb outcomes and limb salvage in patients with chronic LEAD.

Methods and results

Study inclusion criteria were: enrolment of patients with LEAD, randomized allocation to more vs. less intense antithrombotic therapy [more vs. less intense single-antiplatelet therapy (SAPT); dual-antiplatelet therapy vs. SAPT; dual antithrombotic therapy vs. SAPT or oral anticoagulant]; enrolment of ≥200 patients; reporting of at least one of following outcomes: limb amputation or revascularization. Seven randomized studies enrolling 30 447 patients were included. Over a median follow-up of 24 months, more vs. less intense antithrombotic therapy or placebo significantly reduced the risk of limb revascularization [relative risk (RR) 0.89, 95% confidence interval (CI) 0.83–0.94] and limb amputation (RR 0.63, 95% CI 0.46–0.86), as well as stroke (RR 0.82, 95% CI 0.70–0.97). There was no statistically significant effect on the risk of myocardial infarction (RR 0.98, 95% CI 0.87–1.11), all-cause (RR 0.93, 95% CI 0.86–1.01), and cardiovascular death (RR 0.97, 95% CI 0.86–1.08). Risk of major bleeding increased (RR 1.23, 95% CI 1.04–1.44).

Conclusion

In patients with LEAD, more intense antithrombotic therapy reduces the risk of limb amputation and revascularization as well as stroke with an increase in the risk of bleeding events.

Tumour Necrosis Factor-α Inhibition Improves Stroke Outcome in a Mouse Model of Rheumatoid Arthritis

Rheumatoid Arthritis (RA) is a chronic inflammatory disorder where incidence and severity of myocardial infarction are increased. Data on the incidence and outcome of stroke are conflicting. Thus, we investigated outcome after Ischemia/Reperfusion (I/R) brain injury in a mouse model of RA and assessed for the role of the tumour necrosis factor-α (TNF-α) inhibitor Infliximab herein. We used a TNF-α reliant mouse model of RA. RA and wildtype (WT) animals were treated with vehicle (RA/WT) or Infliximab (RA Infliximab) for 4 weeks, before undergoing I/R brain injury. RA-animals displayed larger strokes and poorer neurological performance. Immunohistochemistry on brain sections revealed increased numbers of resident and peripheral innate immune cells (microglia and macrophages); increased Blood-Brain-Barrier (BBB)-disruption; decreased levels of the tight junction proteins (TJPs) claudin-5 and occludin; increased expression of matrix-metalloproteinases (MMP)-3 and -9 and enhanced lipid peroxidation. Treatment with Infliximab corrected these alterations. We show that RA associates to worse stroke-outcome via exacerbated BBB degradation by decrease of the TJPs claudin-5 and occludin. We identified MMPs-3 and -9 and increased oxidative stress as potential mediators thereof. Increased numbers of resident and peripheral innate immune cells (microglia and macrophages) may in turn contribute to all these effects. Infliximab-treatment restored the phenotype of RA-mice to baseline. Our data provide evidence clearly linking RA to adverse stroke-outcome in mice and indicate an approved TNF-α inhibitor as a potential strategy to reduce stroke-burden in this setting.

Whole blood omega-3 fatty acid concentrations are inversely associated with blood pressure in young, healthy adults

BACKGROUND

Omega-3 fatty acids (n - 3 FA) may have blood pressure (BP)-lowering effects in untreated hypertensive and elderly patients. The effect of n - 3 FA on BP in young, healthy adults remains unknown. The Omega-3 Index reliably reflects an individuals' omega-3 status. We hypothesized that the Omega-3 Index is inversely associated with BP levels in young healthy adults.

METHODS

The current study (n = 2036) is a cross-sectional study investigating the baseline characteristics of a cohort, which includes healthy adults, age 25-41 years. Individuals with cardiovascular disease, known diabetes or a BMI higher than 35 kg/m were excluded. The Omega-3 Index was determined in whole blood using gas chromatography. Association with office and 24-h BP was assessed using multivariable linear regression models adjusted for potential confounders.

RESULTS

Median Omega-3 Index was 4.58% (interquartile range 4.08; 5.25). Compared with individuals in the lowest Omega-3 Index quartile, individuals in the highest had a SBP and DBP that was 4 and 2 mmHg lower, respectively (P < 0.01). A significant linear inverse relationship of the Omega-3 Index with 24-h and office BP was observed. Per 1-U increase in log-transformed Omega-3 Index the lowering in BP (given as multivariable adjusted β coefficients; 95% confidence interval) was -2.67 mmHg (-4.83; -0.51; P = 0.02) and -2.30 mmHg (-3.92; -0.68; P = 0.005) for 24-h SBP and DBP, respectively.

CONCLUSION

A higher Omega-3 Index is associated with statistically significant, clinically relevant lower SBP and DBP levels in normotensive young and healthy individuals. Diets rich in n - 3 FA may be a strategy for primary prevention of hypertension.

Loss of Sirt3 accelerates arterial thrombosis by increasing formation of neutrophil extracellular traps and plasma tissue factor activity

Aims

Sirtuin 3 (Sirt3) is a mitochondrial, nicotinamide adenine dinucleotide (NAD+)-dependent deacetylase that reduces oxidative stress by activation of superoxide dismutase 2 (SOD2). Oxidative stress enhances arterial thrombosis. This study investigated the effects of genetic Sirt3 deletion on arterial thrombosis in mice in an inflammatory setting and assessed the clinical relevance of these findings in patients with ST-elevation myocardial infarction (STEMI).

Methods and results

Using a laser-induced carotid thrombosis model with lipopolysaccharide (LPS) challenge, in vivo time to thrombotic occlusion in Sirt3-/- mice (n = 6) was reduced by half compared to Sirt3+/+ wild-type (n = 8, P < 0.01) controls. Ex vivo analyses of whole blood using rotational thromboelastometry revealed accelerated clot formation and increased clot stability in Sirt3-/- compared to wild-type blood. rotational thromboelastometry of cell-depleted plasma showed accelerated clotting initiation in Sirt3-/- mice, whereas overall clot formation and firmness remained unaffected. Ex vivo LPS-induced neutrophil extracellular trap formation was increased in Sirt3-/- bone marrow-derived neutrophils. Plasma tissue factor (TF) levels and activity were elevated in Sirt3-/- mice, whereas plasma levels of other coagulation factors and TF expression in arterial walls remained unchanged. SOD2 expression in bone marrow -derived Sirt3-/- neutrophils was reduced. In STEMI patients, transcriptional levels of Sirt3 and its target SOD2 were lower in CD14+ leukocytes compared with healthy donors (n = 10 each, P < 0.01).

Conclusions

Sirt3 loss-of-function enhances experimental thrombosis in vivo via an increase of neutrophil extracellular traps and elevation of TF suggesting thrombo-protective effects of endogenous Sirt3. Acute coronary thrombosis in STEMI patients is associated with lower expression levels of SIRT3 and SOD2 in CD14+ leukocytes. Therefore, enhancing SIRT3 activity by pan-sirtuin activating NAD+-boosters may provide a novel therapeutic target to prevent or treat thrombotic arterial occlusion in myocardial infarction or stroke.

Amotosalen/ultraviolet A pathogen inactivation technology reduces platelet activatability, induces apoptosis and accelerates clearance

Amotosalen and ultraviolet A (UVA) photochemical-based pathogen reduction using the Intercept™ Blood System (IBS) is an effective and established technology for platelet and plasma components, which is adopted in more than 40 countries worldwide. Several reports point towards a reduced platelet function after Amotosalen/UVA exposure. The study herein was undertaken to identify the mechanisms responsible for the early impairment of platelet function by the IBS. Twenty-five platelet apheresis units were collected from healthy volunteers following standard procedures and split into 2 components, 1 untreated and the other treated with Amotosalen/UVA. Platelet impedance aggregation in response to collagen and thrombin was reduced by 80% and 60%, respectively, in IBS-treated units at day 1 of storage. Glycoprotein Ib (GpIb) levels were significantly lower in IBS samples and soluble glycocalicin correspondingly augmented; furthermore, GpIbα was significantly more desialylated as shown by Erythrina Cristagalli Lectin (ECL) binding. The pro-apoptotic Bak protein was significantly increased, as well as the MAPK p38 phosphorylation and caspase-3 cleavage. Stored IBS-treated platelets injected into immune-deficient nonobese diabetic/severe combined immunodeficiency (NOD/SCID) mice showed a faster clearance. We conclude that the IBS induces platelet p38 activation, GpIb shedding and platelet apoptosis through a caspase-dependent mechanism, thus reducing platelet function and survival. These mechanisms are of relevance in transfusion medicine, where the IBS increases patient safety at the expense of platelet function and survival.

Omega-3 fatty acids predict recurrent venous thromboembolism or total mortality in elderly patients with acute venous thromboembolism

Essentials The role of omega-3 fatty acids (n-3 FAs) in recurrent venous thromboembolism (VTE) is unknown. Association of n-3 FAs with recurrent VTE or total mortality was investigated in 826 patients. Whole blood n-3 FAs were inversely correlated with recurrent VTE or total mortality. Major and non-major bleeding was not increased in patients with higher levels of n-3 FAs.

SUMMARY

Background The role of omega-3 fatty acids (n-3 FAs) in recurrent venous thromboembolism (VTE) remains unknown. Objectives To investigate the association of n-3 FAs with recurrent VTE or total mortality at 6 months and 3 years. Methods N-3 FAs were assessed in 826 patients aged ≥ 65 years, categorized into low, medium and high based on the 25th and 75th percentile. Mean follow-up was 29 months. Results At 6 months, subjects with medium (adjusted hazard ratio [HR], 0.37; 95% confidence interval [CI], 0.22-0.62) and high n-3 FA levels (adjusted HR, 0.36; 95% CI, 0.20-0.67) were less likely to develop recurrent VTE or total mortality, compared with those with low n-3 FAs. At 3 years, medium levels (adjusted HR, 0.67; 95% CI, 0.47-0.96) were associated with lower risk of recurrent VTE or total mortality. As compared with low n-3 FAs, the adjusted sub-hazard ratio [SHR] of recurrent VTE was 0.39 (95% CI, 0.15-0.99) in patients with medium and 0.17 (95% CI, 0.03-0.82) in patients with high n-3 FAs. The cumulative incidence of recurrent VTE was lower in the medium and high n-3 FA groups as compared with the low n-3 FA groups, but seems to have worn off after 3 years. The incidence of major and non-major bleeding was not greater in the high n-3 FA group. Conclusion Higher levels of n-3 FAs were associated with a lower risk of recurrent VTE or total mortality in elderly patients with VTE, but not with greater bleeding risk.

Ticagrelor, but not clopidogrel, reduces arterial thrombosis via endothelial tissue factor suppression

AIMS

The P2Y₁₂ antagonist ticagrelor reduces mortality in patients with acute coronary syndrome (ACS), compared with clopidogrel, and the mechanisms underlying this effect are not clearly understood. Arterial thrombosis is the key event in ACS; however, direct vascular effects of either ticagrelor or clopidogrel with focus on arterial thrombosis and its key trigger tissue factor have not been previously investigated.

METHODS AND RESULTS

Human aortic endothelial cells were treated with ticagrelor or clopidogrel active metabolite (CAM) and stimulated with tumour necrosis factor-alpha (TNF-α); effects on procoagulant tissue factor (TF) expression and activity, its counter-player TF pathway inhibitor (TFPI) and the underlying mechanisms were determined. Further, arterial thrombosis by photochemical injury of the common carotid artery, and TF expression in the murine endothelium were examined in C57BL/6 mice treated with ticagrelor or clopidogrel. Ticagrelor, but not CAM, reduced TNF-α-induced TF expression via proteasomal degradation and TF activity, independently of the P2Y₁₂ receptor and the equilibrative nucleoside transporter 1 (ENT1), an additional target of ticagrelor. In C57BL/6 mice, ticagrelor prolonged time to arterial occlusion, compared with clopidogrel, despite comparable antiplatelet effects. In line with our in vitro results, ticagrelor, but not clopidogrel, reduced TF expression in the endothelium of murine arteries.

CONCLUSION

Ticagrelor, unlike clopidogrel, exhibits endothelial-specific antithrombotic properties and blunts arterial thrombus formation. The additional antithrombotic properties displayed by ticagrelor may explain its greater efficacy in reducing thrombotic events in clinical trials. These findings may provide the basis for new indications for ticagrelor.

The MAP kinase JNK2 mediates cigarette smoke-induced arterial thrombosis

Despite public awareness of its deleterious effects, smoking remains a major cause of death. Indeed, it is a risk factor for atherothrombotic complications and in line with this, the introduction of smoking ban in public areas reduced smoking-associated cardiovascular complications. Nonetheless, smoking remains a major concern, and molecular mechanisms by which it causes cardiovascular disease are not known. Peripheral blood monocytes from healthy smokers displayed increased JNK2 and tissue factor (TF) gene expression compared to non-smokers (n=15, p<0.05). Similarly, human aortic endothelial cells exposed to cigarette smoke total particulate matter (CS-TPM) revealed increased TF expression mediated by JNK2 (n=4; p<0.05). Wild-type and JNK2^-/- mice were exposed to cigarette smoke for two weeks after which arterial thrombosis was investigated. Wild-type mice exposed to smoke displayed reduced time to thrombotic arterial occlusion (n=8; p<0.05) and increased tissue factor activity (n=7; p<0.05) as compared to wild-type controls (n=6), while JNK2^-/-mice exposed to smoke maintained an unaltered thrombotic potential (n=8; p=NS) and tissue factor activity (n=8) comparable to that of JNK2^-/- and wild-type controls (n=6; p=NS). Smoking caused an increased production of reactive oxygen species (ROS) in wild-type but not in JNK2^-/- mice (n=7; p<0.05 for wild-type mice and n=5-6; p=NS for JNK2^-/- mice). In conclusion, the MAP kinase JNK2 mediates cigarette smoke-induced TF activation, arterial thrombosis and ROS production. These results underscore a major role of JNK2 in smoke-mediated thrombus formation and may offer an attractive target to prevent smoke-related thrombosis in those subjects which do not manage quitting.

Post-ischaemic silencing of p66Shc reduces ischaemia/reperfusion brain injury and its expression correlates to clinical outcome in stroke

AIM

Constitutive genetic deletion of the adaptor protein p66(Shc) was shown to protect from ischaemia/reperfusion injury. Here, we aimed at understanding the molecular mechanisms underlying this effect in stroke and studied p66(Shc) gene regulation in human ischaemic stroke.

METHODS AND RESULTS

Ischaemia/reperfusion brain injury was induced by performing a transient middle cerebral artery occlusion surgery on wild-type mice. After the ischaemic episode and upon reperfusion, small interfering RNA targeting p66(Shc) was injected intravenously. We observed that post-ischaemic p66(Shc) knockdown preserved blood-brain barrier integrity that resulted in improved stroke outcome, as identified by smaller lesion volumes, decreased neurological deficits, and increased survival. Experiments on primary human brain microvascular endothelial cells demonstrated that silencing of the adaptor protein p66(Shc) preserves claudin-5 protein levels during hypoxia/reoxygenation by reducing nicotinamide adenine dinucleotide phosphate oxidase activity and reactive oxygen species production. Further, we found that in peripheral blood monocytes of acute ischaemic stroke patients p66(Shc) gene expression is transiently increased and that this increase correlates with short-term neurological outcome.

CONCLUSION

Post-ischaemic silencing of p66(Shc) upon reperfusion improves stroke outcome in mice while the expression of p66(Shc) gene correlates with short-term outcome in patients with ischaemic stroke.

Genetic deletion of the adaptor protein p66Shc increases susceptibility to short-term ischaemic myocardial injury via intracellular salvage pathways

AIMS

Several intracellular mediators have been implicated as new therapeutic targets against myocardial ischaemia and reperfusion injury. However, clinically effective salvage pathways remain undiscovered. Here, we focused on the potential role of the adaptor protein p66(Shc) as a regulator of myocardial injury in a mouse model of cardiac ischaemia and reperfusion.

METHODS AND RESULTS

Adult male p66(Shc) deficient (p66(Shc) (-/-)) and C57Bl/6 wild-type (WT) mice were exposed to 30, 45, or 60 min of ischaemia and reperfusion (5, 15 min, or 24 h). Infarct size, systemic and intracardiac inflammation and oxidants, as well as cytosolic and mitochondrial apoptotic pathways were investigated. Following 30, but not 45 or 60 min of ischaemia, genetic p66(Shc) deficiency was associated with larger infarcts. In WT mice, in vivo p66(Shc) knock down by siRNA with transient protein deficiency confirmed these findings. P66(Shc) inhibition was not associated with any modification in post-infarction inflammation, oxidative burst nor cardiac vessel density or structure. However, in p66(Shc) (-/-) mice activation of the protective and anti-apoptotic Reperfusion Injury Salvage Kinases and Survivor Activating Factor Enhancement pathways were blunted and mitochondrial swelling and cellular apoptosis via the caspase-3 pathway increased compared with WT.

CONCLUSIONS

Genetic deletion of p66(Shc) increased susceptibility to myocardial injury in response to short-term ischaemia and reperfusion in mice. Still, additional studies are needed for assessing the role of this pathway in acute coronary syndrome patients.

High-density lipoprotein from patients with coronary heart disease loses anti-thrombotic effects on endothelial cells: impact on arterial thrombus formation

Thrombus formation is determined by the balance between pro- thrombotic mediators and anti-thrombotic factors.High-density lipoprotein (HDL) from healthy subjects exerts anti-thrombotic properties. Whether this is also the case for HDL from patients with stable coronary heart disease (CHD) or acute coronary syndrome (ACS) is unknown.In human aortic endothelial cells in culture,HDL (50 µg/ml) from healthy subjects (HS) inhibited thrombin-induced tissue factor (TF) expression and activity, while HDL (50 µg/ml) from CHD and ACS patients did not. Similarly, only healthy HDL increased endothelial tissue factor pathway inhibitor (TFPI) expression and tissue plasminogen activator (tPA) release, while HDL from CHD and ACS patients had no effect. Healthy HDL inhibited thrombin-induced plasminogen activator inhibitor type 1 (PAI-1) expression, while HDL from ACS patients enhanced endothelial PAI-1 expression. Inhibition of nitric oxide (NO) formation with L-NAME (100 µmol/l) abolished the anti-thrombotic effects of healthy HDL on TF, TFPI, and tPA expression. The exogenous nitric oxide donor, DETANO, mimicked the effects of healthy HDL and counterbalanced the loss of anti-thrombotic effects of HDL from CHD and ACS patients in endothelial cells. In line with this observation, healthy HDL, in contrast to HDL from CHD and ACS patients, increased endothelial NO production. In the laser-injured carotid artery of the mouse, thrombus formation was delayed in animals treated with healthy HDL compared with mice treated with vehicle or HDL from patients with CHD or ACS. In conclusion, HDL from CHD and ACS patients loses the ability of healthy HDL to suppress TF and to increase TFPI and t-PA and instead enhances PAI-1 and arterial thrombus formation.

Abstract 77: Endothelial LOX-1 Protects Against Arterial Thrombosis via Activation of the Oct-1/SIRT1 Pathway

Background: The lectin-like oxLDL receptor-1 (LOX-1) promotes the endothelial uptake of oxidized low-density lipoprotein (oxLDL). However, LOX-1 is involved in several other biological processes and its role in arterial thrombus formation remains unknown. The present study was designed to investigate whether LOX-1 activation plays a role in thrombus formation in vivo.

Methods and Results: Endothelial-specific LOX-1 transgenic mice were generated using the Tie2 promoter (LOX-1TG). While plasma levels of oxLDL were comparable, carotid tissue oxLDL content was markedly increased in LOX-1TG as compared to wild type (WT). Arterial thrombus formation was assessed using an in vivo photochemical injury model. Time to arterial occlusion was prolonged in LOX-1TG as compared to WT. In line with this, tissue factor (TF) expression and activity were reduced by 50% in the carotid arteries of LOX-1TG mice. This effect was mediated by the activation of the transcription factor Oct-1 leading to upregulation of mammalian deacetylase SIRT1 via binding to its promoter and subsequent inhibition of NF-κB signaling as demonstrated by siRNA experiments. This was further confirmed in LOX-1TG endothelial cells (EC) where expression of Oct-1 and SIRT1 was increased upon exposure to oxLDL. Increased expression of SIRT1 was further associated with decreased DNA-binding of RelA/p65 subunit of NF-κB.

Conclusions: LOX-1 activates a novel compensatory pathway which protects against arterial thrombus formation in vivo. These unexpected findings suggest that Oct-1/SIRT1 signaling may represent a novel target for the prevention of arterial thrombus formation in the setting of hyperlipidemia and atherosclerosis.

Abstract 539: P66Shc Adaptor Protein Protects From Short-Term Ischemic Myocardial Injury via Intracellular Salvage Pathways

Background: Formation of reactive oxygen species (ROS) contributes to many pathophysiological processes. Although ROS production is also involved in some physiological processes, the imbalance between their generation and removal, i.e. oxidative stress, plays a major role in myocardial injury caused by ischemia/reperfusion (I/R). The mammalian Shc locus encodes three Shc isoforms: p46Shc, p52Shc and p66Shc. The p66Shc is not involved in mitogenic signals as p46Shc/p52Shc, but it functions as a critical mediator of intracellular oxidative signal transduction. Various studies relate p66Shc to cardiovascular disease; however, few data are available on the role of p66Shc in myocardial I/R.

Methods and Results: 8-12-week-old male p66Shc deficient (p66Shc-/-) mice and corresponding C57Bl/6 wild-type (WT) control mice were subjected in vivo to different durations of I (30, 45 and 60 min) followed by 24h of R. Infarct size was assessed morphologically. After 30 min of ischemia (I), p66Shc-/- mice developed markedly larger infarcts as compared to WT. This effect was confirmed by in vivo silencing of p66Shc prior to I/R. Both genetic deletion and silencing of p66Shc displayed increased post-ischemic levels of serum cardiac troponin I. However, the observed effect on infarct size was limited to 30 min of I since by increasing ischemia duration to either 45 or 60 min infarct size did no longer differ between p66Shc-/- and WT mice. Moreover, differently from WT, infarct size in p66Shc-/- was not significantly larger with increasing duration of I (from 30 to 60 min). On the molecular level the observed effect was linked to the inhibition of phosphorylation of protein kinase Akt and transcription factor STAT3 - two key members of prosurvival pathways RISK and SAFE, respectively. Inhibition of STAT3 activation further led to mitochondrial swelling and cellular apoptosis in cardiac tissue of p66Shc-/- mice.

Conclusions: Our data suggest that genetic deletion of p66Shc leads to an increased sensitivity to myocardial infarction with larger infarcts with shorter, but not prolonged I, and that prosurvival pathways are involved. Therefore, activation of p66Shc may provide resistance to I and represent a novel therapeutic target in the early phase of myocardial infarction.

[The effects of Omega-3 fatty acids in clinical medicine]

Effects of Omega-3 fatty acids (n-3 FA) in particular on the development of cardiovascular disease (CVD) are of major interest. Many experimental studies reported their anti-inflammatory, anti-thrombotic and anti-atherosclerotic properties and suggested favourable effects on the prevention of CVD. While the majority of former studies showed a benefit of n-3 FA acid intake, recent clinical trials using n-3 supplements on top of established medication and prudent nutrition did not confirm these findings. The conflicting data may be due to several factors such as the selection of study population with different sizes or characteristics as well as choosing different doses or types of n-3 FA. The most recent meta-analyses observed clear benefits of fish consumption, but not of n-3 capsules intake. Furthermore, a nutrition rich in plant-derived n-3 FA alpha-linolenic acid has been found to have beneficial effects on the development of cardio- and cerebrovascular diseases.

Reduction of albumin urinary excretion is associated with reduced cardiovascular events in hypertensive and/or diabetic patients. A meta-regression analysis of 32 randomized trials

BACKGROUND

The association between renal dysfunction and risk of cardiovascular (CV) events and mortality has been reported in several studies. However, it is unclear whether reduction in urinary albumin excretion (UAE) is associated with reduced risk of clinical events. Therefore, we sought to investigate, in a meta-regression analysis of randomized studies enrolling hypertensive and/or diabetic patients, whether changes in UAE are associated with changes in CV outcomes and all-cause mortality.

METHODS

MEDLINE, ISI Web of Science, Cochrane Database and Scopus were searched for randomized trials enrolling more than 200 diabetic and/or hypertensive patients, reporting UAE at baseline and at end of follow-up and CV events [CV death, myocardial infarction (MI), and stroke], as well all-cause mortality.

RESULTS

Thirty-two trials enrolling 80,812 participants were included in analyses. Meta-regression analysis showed that each 10% reduction of UAE was significantly associated with 13% reduction of MI (Regression Coefficient [RC]:0.0055; 95% Confidence Interval [CI]:0.0014 to 0.0095; p=0.010), with 29% reduction of stroke (RC:0.0124; CI:0.0030 to 0.0218; p=0.013) and with 14% reduction of the composite outcome (CV death, MI, stroke)(RC:0.0059; CI:0.0027 to 0.0090; p=0.001), whereas not significantly associated with all-cause (RC:0.0028; CI:-0.0047 to 0.0103; p=0.486) and CV mortality (RC:0.0028; CI:-0.0047 to 0.0103; p=0.447). Results were mostly confirmed by sensitivity analysis. No heterogeneity or publication bias was detected.

CONCLUSIONS

Reduction in UAE is associated with reduced risk of MI and stroke in diabetic and/or hypertensive patients. These findings suggest that UAE changes may represent a valuable intermediate end-point for CV risk evaluation in clinical practice.