Thrombin generation and atherosclerosis

Antithrombotic Effect of a Bivalent DNA Aptamer of Thrombin

Thrombin plays a critical role in both coagulation and platelet activation, and its interaction with thrombin-protease-activated receptor 1 (PAR1) on platelets and vascular smooth muscle cells (VSMCs) leads to a series of pathological processes such as thrombosis, restenosis, and atherosclerosis. This study investigated the antithrombotic properties of a bivalent DNA aptamer (bApt) with phosphorothioate backbone modification designed to inhibit thrombin, with a specific focus on its ability to regulate the thrombin-PAR1 signaling pathway. The results showed that bApt modulated the thrombin-PAR1 pathway, effectively reduced thrombus formation, platelet aggregation, and VSMC proliferation. Key findings from the study highlight that bApt successfully prolonged coagulation reaction time (R value), coagulation time (K value), maximum amplitude (MA) and reduced coagulation angle (α value), and also prolonged thrombin time (TT) and activated partial thromboplastin time (APTT), in a dose-dependent manner. Moreover, in an arterial injury model, bApt reduced thrombus formation significantly, supporting its potential as a therapeutic agent for thrombotic diseases.

One immune cell to bind them all: platelet contribution to neurodegenerative disease

Alzheimer's disease (AD) and related dementias (ADRD) collectively affect a significant portion of the aging population worldwide. The pathological progression of AD involves not only the classical hallmarks of amyloid beta (Aβ) plaque buildup and neurofibrillary tangle development but also the effects of vasculature and chronic inflammatory processes. Recently, platelets have emerged as central players in systemic and neuroinflammation. Studies have shown that patients with altered platelet receptor expression exhibit accelerated cognitive decline independent of traditional risk factors. Additionally, platelets from AD patients exhibit heightened unstimulated activation compared to control groups. Platelet granules contain crucial AD-related proteins like tau and amyloid precursor protein (APP). Dysregulation of platelet exocytosis contributes to disease phenotypes characterized by increased bleeding, stroke, and cognitive decline risk. Recent studies have indicated that these effects are not associated with the quantity of platelets present in circulation. This underscores the hypothesis that disruptions in platelet-mediated inflammation and healing processes may play a crucial role in the development of ADRD. A thorough look at platelets, encompassing their receptors, secreted molecules, and diverse roles in inflammatory interactions with other cells in the circulatory system in AD and ADRD, holds promising prospects for disease management and intervention. This review discusses the pivotal roles of platelets in ADRD.

Platelet-fibrin clot strength and platelet reactivity predicting cardiovascular events after percutaneous coronary interventions

BACKGROUND AND AIMS

Platelet-fibrin clot strength (PFCS) is linked to major adverse cardiovascular event (MACE) risk. However, the association between PFCS and platelet reactivity and their prognostic implication remains uncertain in patients undergoing percutaneous coronary intervention (PCI).

METHODS

In PCI-treated patients (n = 2512) from registry data from January 2010 to November 2018 in South Korea, PFCS using thromboelastography and platelet reactivity using VerifyNow were measured. High PFCS (PFCSHigh) was defined as thromboelastography maximal amplitude ≥ 68 mm, and high platelet reactivity (HPR) was defined as >208 P2Y12 reaction units. Patients were stratified into four groups according to maximal amplitude and P2Y12 reaction unit levels: (i) normal platelet reactivity (NPR)-PFCSNormal (31.8%), (ii) HPR-PFCSNormal (29.0%), (iii) NPR-PFCSHigh (18.1%), and (iv) HPR-PFCSHigh (21.1%). Major adverse cardiovascular event (all-cause death, myocardial infarction, or stroke) and major bleeding were followed up to 4 years.

RESULTS

High platelet reactivity and PFCSHigh showed an additive effect for clinical outcomes (log-rank test, P < .001). Individuals with NPR-PFCSNormal, NPR-PFCSHigh, HPR-PFCSNormal, and HPR-PFCSHigh demonstrated MACE incidences of 7.5%, 12.6%, 13.4%, and 19.3%, respectively. The HPR-PFCSHigh group showed significantly higher risks of MACE compared with the NPR-PFCSNormal group [adjusted hazard ratio (HRadj) 1.89; 95% confidence interval (CI) 1.23-2.91; P = .004] and the HPR-PFCSNormal group (HRadj 1.60; 95% CI 1.12-2.27; P = .009). Similar results were observed for all-cause death. Compared with HPR-PFCSNormal phenotype, NPR-PFCSNormal phenotype was associated with a higher risk of major bleeding (HRadj 3.12; 95% CI 1.30-7.69; P = .010).

CONCLUSIONS

In PCI patients, PFCS and platelet reactivity demonstrated important relationships in predicting clinical prognosis. Their combined assessment may enhance post-PCI risk stratification for personalized antithrombotic therapy.

PGC1-Alpha/Sirt3 Signaling Pathway Mediates the Anti-Pulmonary Fibrosis Effect of Hirudin by Inhibiting Fibroblast Senescence

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive fibrotic lung disease for which there is a lack of effective pharmacological treatments. Hirudin, a natural peptide extracted from leeches, has been used for broad pharmacological purposes. In this study, we investigated the therapeutic effects of hirudin on IPF and its related mechanism of action. By constructing a mouse model of pulmonary fibrosis and treating it with hirudin in vivo, we found that hirudin exerted anti-fibrotic, anti-oxidative, and anti-fibroblast senescence effects. Moreover, using an in vitro model of stress-induced premature senescence in primary mouse lung fibroblasts and treating with hirudin, we observed inhibition of fibroblast senescence and upregulation of PGC1-alpha and Sirt3 expression. However, specific silencing of PGC1-alpha or Sirt3 suppressed the anti-fibroblast senescence effect of hirudin. Thus, the PGC1-alpha/Sirt3 pathway mediates the anti-fibroblast senescence effect of hirudin, potentially serving as a molecular mechanism underlying its anti-fibrosis and anti-oxidative stress effects exerted on the lungs.

The Etiology of the Thrombotic Phenomena Involved in the Process of Coronary Artery Disease-What Is the Role of Thrombophilic Genes in the Development of This Pathology?

Cardiovascular diseases, among which includes coronary artery disease, represent one of the most important causes of mortality and morbidity worldwide. Research aimed at determining the risk factors involved recognizes a group of "traditional" risk factors, but also more recent studies identified over 100 "novel" ones which may have a role in the disease. Among the latter is the thrombophilia profile of a patient, a pathology well-established for its involvement in venous thromboembolism, but with less studied implications in arterial thrombosis. This paper reviews the literature, explaining the pathophysiology of the thrombophilia causes associated most with coronary thrombosis events. Results of several studies on the subject, including a meta-analysis with over 60,000 subjects, determined the significant involvement of factor V Leiden, prothrombin G20210A mutation, plasminogen activator inhibitor-1 and antiphospholipid syndrome in the development of coronary artery disease. The mechanisms involved are currently at different stages of research, with some already established and used as therapeutic targets.

Thrombin generation and all-cause mortality in The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

INTRODUCTION

Thrombin generation assay (TGA) is a laboratory method that provides the global evaluation of hemostasis. The association between thrombin generation and all-cause mortality is poorly investigated and results are contradictory. This study evaluated whether TGA parameters are associated with all-cause mortality in a prospective cohort.

METHODS

This study was conducted in 2,588 participants enrolled at baseline of the Brazilian Longitudinal Study of Adult Health (ELSA-Brasil). TGA was performed using the Calibrated Automated Thrombogram (CAT) method, and its parameters lagtime, time-to-peak, peak, Endogenous Thrombin Potential (ETP) and normalized ETP (nETP) were evaluated according to the reference interval (RI). The association between TGA parameters and all-cause mortality was estimated by Cox regression and adjusted for confounders.

RESULTS

The mean follow-up time was 6.6 ± 2.7 years and 85 deaths occurred. After adjustment, time-to-peak values above the RI at low and high tissue factor (TF) concentrations were associated with higher risk of death [HR = 2.45 (95 % CI: 1.17-5.13) and HR = 2.24 (95 % CI: 1.02-4.93), respectively] and nETP and peak values below RI at high TF concentration were associated with higher risk of death [HR = 3.85 (95 % CI: 1.39-10.68) and HR = 2.56 (95 % CI: 1.17-5.61), respectively].

CONCLUSIONS

Delayed thrombin generation was associated with higher risk of all-cause mortality.

An aggregation-induced emission sensor combined with UHPLC-Q-TOF/MS for fast identification of anticoagulant active ingredients from traditional Chinese medicine

Xuebijing injection (XBJ) has a good therapeutic effect on the patients with severe coronavirus disease, but the material basis of XBJ with the anticoagulant effect to improve the coagulopathy and thromboembolism is still unclear. Herein, we developed a new strategy based on aggregation-induced emission (AIE) for monitoring thrombin activity and screening thrombin inhibitors from XBJ. The molecule AIE603 and the thrombin substrate peptide S-2238 were formed into AIE nanoparticle (AIENP) which emitted notable fluorescence due to the restriction of intramolecular motions. In the presence of thrombin, AIENP was specifically hydrolyzed and AIE603 was released from AIENP, leading to the decrease of fluorescence intensity. Furthermore, AIENP was combined with ultra-high performance liquid chromatography-fraction collector (UHPLC-FC) and ultra-high performance liquid chromatography quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) for separation, preparation, screening and identification of the thrombin inhibitors from XBJ, a total of 58 chemical constituents were identified, among which 6 compounds possessed higher anticoagulant activity. Notably, the overall inhibition rate of the 6 mixed standards was equivalent to about 60% of the inhibition rate of XBJ. Therefore, this work provides a novel, cheap and simple method for monitoring thrombin activity and is promising to screen active substances from traditional Chinese medicines.

The Complementary Effects of Dabigatran Etexilate and Exercise Training on the Development and Stability of the Atherosclerotic Lesions in Diabetic ApoE Knockout Mice

Aim: To determine the complementary effects of dabigatran etexilate (DE), exercise training (ET), and combination (DE + ET) on the development and stability of the atherosclerotic lesions in diabetic apoE knockout (apoE-/-) mice. Methods: In 48 male apoE-/- diabetic mice, streptozotocin (STZ) was induced for 5 consecutive days. Mice received a high-fat diet (HFD) for 8 weeks and then were randomized into four groups (1. Control/CG, 2. DEG: HFD with DE, 3. ETG: ET on treadmill, 4. DE + ETG: combination DE and ET treatment). At the end of the eighth week, all mice were euthanatized and morphometry of the aortic lesions at the level of aortic valve was obtained. Collagen, elastin, MCP-1, TNF-a, matrix metalloproteinases (MMP-2,-3,-9), and TIMP-1 concentrations within plaques at the aortic valve were determined. Results: All active groups had significantly smaller aorta stenosis (DEG:7.9 ± 2.2%, ETG:17.3 ± 5.3%, DE + ETG:7.1 ± 2.7%) compared to CG (23.3 ± 5.5% p < 0.05), reduced the relative intra-plaque content of MCP-1, macrophages, MMP-3, and MMP-9, and considerably increased collagen, elastin, and TIMP-1 (p < 0.05). Group 4 showed the most pronounced results (p < 0.05). Both DEG and DE + ETG significantly reduced MMP-2 and TNF-a concentrations compared to ETG and CG (p < 0.010). Conclusion: DE and ET treatment of diabetic apoE-/- mice resulted in complementary amelioration of atherosclerotic lesions development and stability, mediated by the anti-inflammatory modulation of both DE and ET.

Thrombin, a Key Driver of Pathological Inflammation in the Brain

Neurodegenerative diseases, including Alzheimer's disease (AD), are major contributors to death and disability worldwide. A multitude of evidence suggests that neuroinflammation is critical in neurodegenerative disease processes. Exploring the key mediators of neuroinflammation in AD, a prototypical neurodegenerative disease, could help identify pathologic inflammatory mediators and mechanisms in other neurodegenerative diseases. Elevated levels of the multifunctional inflammatory protein thrombin are commonly found in conditions that increase AD risk, including diabetes, atherosclerosis, and traumatic brain injury. Thrombin, a main driver of the coagulation cascade, has been identified as important to pathological events in AD and other neurodegenerative diseases. Furthermore, recent evidence suggests that coagulation cascade-associated proteins act as drivers of inflammation in the AD brain, and studies in both human populations and animal models support the view that abnormalities in thrombin generation promote AD pathology. Thrombin drives neuroinflammation through its pro-inflammatory activation of microglia, astrocytes, and endothelial cells. Due to the wide-ranging pro-inflammatory effects of thrombin in the brain, inhibiting thrombin could be an effective strategy for interrupting the inflammatory cascade which contributes to neurodegenerative disease progression and, as such, may be a potential therapeutic target for AD and other neurodegenerative diseases.

Integrative analysis of HASMCs gene expression profile revealed the role of thrombin in the pathogenesis of atherosclerosis

We explored the effect of thrombin on human aortic smooth muscle cells (HASMCs) and further analyzed its role in the pathogenesis of atherosclerosis (AS). Thrombin-induced differentially expressed genes (DEGs) in HASMCs were identified by analyzing expression profiles from the GEO. Subsequently, enrichment analysis, GSEA, PPI network, and gene-microRNAs networks were interrogated to identify hub genes and associated pathways. Enrichment analysis results indicated that thrombin causes HASMCs to secrete various pro-inflammatory cytokines and chemokines, exacerbating local inflammatory response in AS. Moreover, we identified 9 HUB genes in the PPI network, which are closely related to the inflammatory response and the promotion of the cell cycle. Additionally, we found that thrombin inhibits lipid metabolism and autophagy of HASMCs, potentially contributing to smooth muscle-derived foam cell formation. Our study deepens a mechanistic understanding of the effect of thrombin on HASMCs and provides new insight into treating AS.

Vitamin D Deficiency is Associated With Increased Plasminogen Activator Inhibitor 1/Plasminogen Activator Inhibitor 2 Ratio in Pregnancy

BACKGROUND

Vitamin D deficiency has recently been suggested as an independent risk factor for thrombosis. Notably, vitamin D deficiency is common in pregnant populations, whom already have an increased thrombotic risk. However, pregnant women are commonly excluded from studies investigating the hemostatic system, and knowledge on the impact of vitamin D on hemostasis in pregnancy is therefore limited.

METHODS

A cross-sectional study comparing the hemostatic profile of pregnant women (gestational week 12.9 ± 0.7) with vitamin D deficiency (≤50 nmol/L) (n = 70) and high adequate vitamin D status (≥100 nmol/L) (n = 59).

RESULTS

Vitamin D deficient women displayed increased plasminogen activator inhibitor 1 levels and an increased plasminogen activator inhibitor 1/plasminogen activator inhibitor 2 ratio, even after adjusting for factors with potential influence on hemostasis (body mass index, smoking and use of fish oil supplements).

CONCLUSIONS

Vitamin D deficiency is associated with increased plasminogen activator inhibitor 1/plasminogen activator inhibitor 2 ratio in pregnant women. As an increased plasminogen activator inhibitor 1/plasminogen activator inhibitor 2 ratio with high plasminogen activator inhibitor 1 levels may increase thrombotic risk and is associated with the development of pregnancy complications, further research is needed to determine the optimal vitamin D supplementation in pregnancy.

Factor V Leiden but not the factor II 20210G>A mutation is a risk factor for premature coronary artery disease: a case-control study in Iran

Background

Factor V Leiden (FVL) and factor II c.∗97G>A (rs1799963) are genetic risk factors for venous thromboembolism. Their contribution to coronary artery disease (CAD) is less clear.

Objectives

This study aimed to investigate the association between FVL, rs1799963, and premature CAD in Iranians.

Methods

We performed a genetic case-control study of 944 cases and 1081 controls from the premature CAD Milano-Iran study, including patients aged 18-55 (female) and 18-45 years (male) who underwent coronary angiography at the Tehran Heart Centre (Iran) in 2004-2011. Cases had luminal stenosis ≥50% in at least 1 main coronary artery or branch. Controls were age- and sex-matched with no CAD history. FVL and rs1799963 were genotyped using TaqMan SNP genotyping assays. Association was tested by logistic regression adjusted for matching factors and ethnicity. Effect modification by sex and cardiovascular risk factors (metabolic [obesity, hypertension, hyperlipidemia, and diabetes], and smoking) was assessed.

Results

The risk of premature CAD was increased by 50% in FVL carriers (adjusted odds ratio [adjOR] 1.54 [95% CI, 0.95-2.48]) and slightly reduced in rs1799963 carriers (adjOR 0.71 [95% CI, 0.40-1.27]). These effects were more pronounced in women than men (FVL, adjOR 1.66 vs 1.25; rs1799963, adjOR 0.60 vs 1.07). The risk of premature CAD was substantially increased in carriers of FVL with at least 1 metabolic risk factor compared with noncarriers without metabolic risk factors (adjOR 25.14 [95% CI, 12.51-50.52]).

Conclusion

FVL but not FII rs1799963 was associated with an increased risk of CAD in young Iranians. This risk increased considerably when combined with metabolic cardiovascular risk factors.

Grass carp SERPINA1 inhibits GCRV infection through degrading CF2

SERPINA1, a member of the serine protease inhibitor family, plays a role in viral infection and inflammation by regulating the activities of serine and cysteine proteases. To date, there have been no reports on the immune function of SERPINA1 in fishes. In this study, we first cloned the serpina1 gene of grass carp (Ctenopharyngodon idellus) and found that it could respond rapidly to the infection of Grass carp reovirus (GCRV), and overexpression of serpina1 could enhance the antiviral response of CIK cells. A polyclonal antibody of SERPINA1 was prepared, and the protein interacting with SERPINA1 was screened by CoIP/MS in grass carp hepatopancreas tissue. It was found that SERPINA1 interacted with coagulation factor 2 (CF2) and could degrade it in a dose-dependent manner. In addition, overexpression of cf2 contributed to the infection of GCRV in CIK cells, whereas co-expression of serpina1 and cf2 in grass carp reduced the copy number of GCRV in cells. The results showed that grass carp SERPINA1 could inhibit GCRV infection by degrading CF2. This study proposes that SERPINA1 can inhibit viral infection through interaction with the coagulation factor, providing new insights into the molecular mechanism of SERPINA1’s antiviral function.

The Molecular Pathways of Pyroptosis in Atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory disease seriously endangering human health, whose occurrence and development is related to many factors. Pyroptosis is a recently identified novel programmed cell death associated with an inflammatory response and involved in the formation and progression of AS by activating different signaling pathways. Protein modifications of the sirtuin family and microRNAs (miRNAs) can directly or indirectly affect pyroptosis-related molecules. It is important to link atherosclerosis, thermogenesis and molecular modifications. This article will systematically review the molecular pathways of pyroptosis in AS, which can provide a new perspective for AS prevention and treatment.

Baicalin Alleviates Thrombin-Induced Inflammation in Vascular Smooth Muscle Cells

Atherosclerosis (AS) is a chronic inflammatory disease of the arterial intima. As AS represents the most common type of vascular disease, it affects millions of individuals and is a source of high morbidity and mortality rates worldwide. Overwhelming evidence indicates that AS-related inflammation is mediated by proinflammatory cytokines, chemokines, adhesion molecules and inflammatory signaling pathways, with each of these factors being shown to play critical roles during the entire progression of AS. While a number of drugs have been approved for use in the treatment of AS, their benefits are modest, which underscores the urgency for the development of new drug therapies. In part, these deficits in effective drugs can be attributable to the lack of a clear understanding of the molecular mechanisms of AS. In this study, we investigate the capacity for thrombin to trigger inflammation and induce cell proliferation in vascular smooth muscle cells (VSMCs). We then assessed the effects of baicalin and its potential mechanisms on VSMC inflammation as induced by thrombin. Baicalin, which is a natural bioactive compound of S. baicalensis Georgi (SBG), exerted a protective effect against thrombin-induced VSMC inflammation as resulting from the upregulation of PAR-1. This protection as exerted by baicalin appears to reside in its capacity to produce an inhibitory effect on the thrombin-induced activation of the ERK1/2 pathway. These findings suggest that baicalin may be a promising candidate for the treatment of atherosclerosis.

Accelerated fibrin clot degradation is associated with arterial thromboembolism in patients following venous thrombosis: a cohort study

Several lines of evidence have suggested that patients following venous thromboembolism (VTE) are at higher risk of arterial thromboembolism (ATE). Prothrombotic fibrin clot characteristics were reported in individuals with cardiovascular risk factors. We investigated whether specific fibrin clot properties measured after 3-4 months of anticoagulation characterize VTE patients with subsequent ATE. We enrolled 320 patients following VTE aged below 70 years (median age, 46). Ten patients were lost to follow-up. ATE occurred in 21 individuals after a median 54 (31-68) months during a follow-up of 87.5 months (incidence 0.94%; 95% confidence interval [CI], 0.59-1.4 per patient-year). Patients with ATE had faster fibrin clot degradation, reflected by maximum rate of D-dimer increase during plasma clot lysis induced by tissue-type plasminogen activator (D-D_rate) at baseline. Clot permeability, turbidimetric variables, clot lysis time, and thrombin generation were unrelated to ATE. Univariable Cox proportional hazards analysis showed that age, diabetes, and D-D_rate were risk factors for subsequent ATE. Increased D-D_rate (by 0.001 mg/L/min; hazard ratio, 1.08; 95% CI 1.02-1.14) was an independent predictor of ATE after adjustment for potential confounders. Faster fibrin clot degradation at 3 months since VTE may increase the risk of ATE among VTE patients during follow-up.

A KLK4 proteinase substrate capture approach to antagonize PAR1

Proteinase-activated receptor-1 (PAR1), triggered by thrombin and other serine proteinases such as tissue kallikrein-4 (KLK4), is a key driver of inflammation, tumor invasiveness and tumor metastasis. The PAR1 transmembrane G-protein-coupled receptor therefore represents an attractive target for therapeutic inhibitors. We thus used a computational design to develop a new PAR1 antagonist, namely, a catalytically inactive human KLK4 that acts as a proteinase substrate-capture reagent, preventing receptor cleavage (and hence activation) by binding to and occluding the extracellular R41-S42 canonical PAR1 proteolytic activation site. On the basis of in silico site-saturation mutagenesis, we then generated KLK4S207A,L185D, a first-of-a-kind 'decoy' PAR1 inhibitor, by mutating the S207A and L185D residues in wild-type KLK4, which strongly binds to PAR1. KLK4S207A,L185D markedly inhibited PAR1 cleavage, and PAR1-mediated MAPK/ERK activation as well as the migration and invasiveness of melanoma cells. This 'substrate-capturing' KLK4 variant, engineered to bind to PAR1, illustrates proof of principle for the utility of a KLK4 'proteinase substrate capture' approach to regulate proteinase-mediated PAR1 signaling.

A thrombin-PAR1/2 feedback loop amplifies thromboinflammatory endothelial responses to the viral RNA analogue poly(I:C)

Activation of blood coagulation and endothelial inflammation are hallmarks of respiratory infections with RNA viruses that contribute significantly to the morbidity and mortality of patients with severe disease. We investigated how signaling by coagulation proteases affects the quality and extent of the response to the TLR3-ligand poly(I:C) in human endothelial cells. Genome-wide RNA profiling documented additive and synergistic effects of thrombin and poly(I:C) on the expression level of many genes. The most significantly active genes exhibiting synergistic induction by costimulation with thrombin and poly(I:C) included the key mediators of 2 critical biological mechanisms known to promote endothelial thromboinflammatory functions: the initiation of blood coagulation by tissue factor and the control of leukocyte trafficking by the endothelial-leukocyte adhesion receptors E-selectin (gene symbol, SELE) and VCAM1, and the cytokines and chemokines CXCL8, IL-6, CXCL2, and CCL20. Mechanistic studies have indicated that synergistic costimulation with thrombin and poly(I:C) requires proteolytic activation of protease-activated receptor 1 (PAR1) by thrombin and transactivation of PAR2 by the PAR1-tethered ligand. Accordingly, a small-molecule PAR2 inhibitor suppressed poly(I:C)/thrombin-induced leukocyte-endothelial adhesion, cytokine production, and endothelial tissue factor expression. In summary, this study describes a positive feedback mechanism by which thrombin sustains and amplifies the prothrombotic and proinflammatory function of endothelial cells exposed to the viral RNA analogue, poly(I:C) via activation of PAR1/2.

Association between lower plasma adiponectin levels and higher plasma thrombin generation parameters in men with type 2 diabetes: role of plasma triglycerides

OBJECTIVE

Previous studies showed a significant association between lower plasma adiponectin levels and higher risk of adverse cardiovascular outcomes in patients with and without type 2 diabetes mellitus (T2DM). Presently, it is uncertain whether lower plasma adiponectin levels are associated with greater plasma thrombin generation in patients with T2DM.

PATIENTS AND METHODS

We studied 82 middle-aged men with non-insulin-treated T2DM [mean age ± SD: 64.1 ± 8 years; median duration of diabetes: 12.5 (inter-quartile range 6-19) years; mean hemoglobin A1c 7.0 ± 0.7%], consecutively attending our diabetes outpatient service over a 6-month period. Using the newly developed fully automated thrombin generation analyzer ST Genesia®, we measured the plasma parameters lag time (LT), time to peak (TP), peak height (PH) and endogenous thrombin potential (ETP) in all participants.

RESULTS

In univariable linear regression analyses, lower plasma adiponectin levels were significantly associated with higher plasma thrombin generation parameters, as reflected by higher values of PH (Pearson's r coefficient = - 0.228, p = 0.039) and EPT (r = - 0.293, p = 0.007). Plasma adiponectin levels were not significantly associated with other thrombin generation parameters (LT and TP). Notably, the significant associations of plasma adiponectin levels with thrombin PH and EPT values persisted after adjustment for age and adiposity measures, but they were lost after additional adjustment for plasma triglycerides.

CONCLUSION

Our findings show for the first time the existence of a significant association between lower levels of plasma adiponectin and greater plasma thrombin generation (as assessed by the ST Genesia® analyzer) in men with non-insulin-treated T2DM, which appears to be largely mediated by plasma triglycerides.

Promising influences of Scutellaria baicalensis and its two active constituents, baicalin, and baicalein, against metabolic syndrome: A review

Metabolic syndrome is known as a group of metabolic abnormalities with features including central obesity, insulin resistance, hypercholesterolemia, hypertriglyceridemia, and hypertension as well as low level of high-density lipoprotein (HDL)-cholesterol. Previous studies showed the ameliorating effects of Scutellaria baicalensis on metabolic syndrome parameters, including antidiabetic, anti-hyperlipidemic, anti-obesity, and antihypertensive. In this review, we deeply and mechanistically evaluated different studies on the effect of S. baicalensis and its two major bioactive constituents, baicalin, and baicalein, on the critical components of metabolic syndrome, including diabetes, hyperlipidemia, obesity, hypertension, and atherosclerosis. Scientific databases, including PubMed, Scopus, and Google Scholar were searched in the English language until the end of June 2020. Accordingly, S. baicalensis, and its two major bioactive constituents, baicalin and baicalein, represent promising effects on the control of metabolic syndrome and its related disorders such as obesity, hyperlipidemia, atherosclerosis, diabetes, and their following complications. In summary, our findings show that S. baicalensis and its active constituents, baicalin and baicalein, by activation and upregulation of AMPK and PPAR-γ as the main signaling in the hemostasis of glucose and lipid metabolisms may be favorable candidates for the prevention and treatment of the metabolic syndrome.

Trimester-specific reference intervals of TAT, TM, tPAI-C and PIC for healthy Chinese pregnant women

AIM

Pregnancy is a hypercoagulability state, the aim of this study was to observe the changes of thrombin-antithrombin complex (TAT), thrombomodulin (TM), tissue plasminogen activator-inhibitor complex (tPAI-C) and plasmin-α2-antiplasmin complex (PIC) during pregnancy and establish trimester-specific reference intervals for Chinese healthy pregnant women.

METHODS

In total 190 Chinese healthy pregnant women (first trimester 59 cases, second trimester 60 cases and third trimester 71 cases) were recruited in North China. TAT, TM, tPAI-C and PIC were processed on Sysmex HISCL 5000 automated chemiluminescence immune detection system. Trimester-specific reference intervals were established with the 2.5th and 97.5th percentile of the distribution.

RESULTS

The reference intervals for TAT, TM, tPAI-C, PIC at trimester 1 were 0.40-3.65 ng/mL, 4.85-8.80 TU/mL, 1.75-6.40 ng/mL, 0.25-1.05 μg/mL, respectively. At trimester 2, the reference intervals were 1.65-8.61 ng/mL, 5.70-9.93 TU/mL, 2.91-7.71 ng/mL, 0.33-2.02 μg/mL, respectively. At trimester 3, the reference intervals were 3.16-12.68 ng/mL, 5.50-14.24 TU/mL, 2.70-10.69 ng/mL, 0.24-1.54 μg/mL, respectively.

CONCLUSIONS

The changes of TAT, TM, tPAI-C, PIC during pregnancy are presented, and trimester-specific reference intervals for healthy pregnant women are described. The levels of TAT, TM, tPAI-C were increased gradually from trimester 1 to trimester 3, while the PIC level remains stable during all trimesters.

High Thrombin Generation after Acute Ischemic Stroke or Transient Ischemic Attack Is Associated with a Reduced Risk of Recurrence: An Observational Cohort Study

Thrombin is increasingly recognized to be of importance for cardiovascular disease. The aim of this study was to investigate the prognostic value of thrombin generation variables in a cohort of patients with acute ischemic stroke (AIS) or transient ischemic attack (TIA). Thrombin generation potential measured by calibrated automated thrombogram (CAT) and prothrombin fragment F1 + 2 was determined in the acute and convalescent phases for a cohort of 190 patients with AIS/TIA. Microvesicle (MV)-induced thrombin generation potential was determined for a subset of patients using modified CAT. Primary outcome was a composite of fatal and nonfatal AIS or myocardial infarction as documented in Swedish registers during a total follow-up of 986 patient-years. Hazard ratios (HRs) were calculated using Cox regression based on variable median split. Peak thrombin and endogenous thrombin potential (ETP) above median in the acute phase were associated with a reduced risk of primary outcome after adjustment for cardiovascular risk factors, HR: 0.50 (0.27-0.92), p = 0.026 and HR: 0.53 (0.28-0.99), p = 0.048, respectively. F1 + 2 was lower in patients than in healthy controls but not associated with outcome. MV-induced peak thrombin above median in the acute phase was associated with recurrent AIS, unadjusted HR: 2.65 (1.03-6.44), p = 0.044. Contrary to expectation, high thrombin generation potential is associated with a reduced risk of recurrent ischemic event in patients with AIS/TIA. Low ETP/peak thrombin combined with high MV-induced peak thrombin can potentially identify patients at high risk of recurrence.

Activatable cell-penetrating peptides: 15 years of research

An important hurdle for the intracellular delivery of large cargo is the cellular membrane, which protects the cell from exogenous substances. Cell-penetrating peptides (CPPs) can cross this barrier but their use as drug delivery vehicles is hampered by their lack of cell type specificity. Over the past years, several approaches have been explored to control the activity of CPPs that can be primed for cellular uptake. Since the first report on such activatable CPPs (ACPPs) in 2004, various methods of activation have been developed. Here, we provide an overview of the different ACPPs strategies known to date and summarize the benefits, drawbacks, and future directions.

Atherosclerosis and Nanomedicine Potential: Current Advances and Future Opportunities

Atherosclerosis is the leading inducement of cardiovascular diseases, which ranks the first cause of global deaths. It is an arterial disease associated with dyslipidemia and changes in the composition of the vascular wall. Besides invasive surgical strategy, the current conservative clinical treatment for atherosclerosis falls into two categories, lipid regulating-based therapy and antiinflammatory therapy. However, the existing strategies based on conventional drug delivery systems have shown limited efficacy against disease development and plenty of side effects. Nanomedicine has great potential in the development of targeted therapy, controlled drug delivery and release, the design of novel specific drugs and diagnostic modalities, and biocompatible scaffolds with multifunctional characteristics, which has led to an evolution in the diagnosis and treatment of atherosclerosis. This paper will focus on the latest nanomedicine strategies for atherosclerosis diagnosis and treatment as well as discussing the potential therapeutic targets during atherosclerosis progress, which could form the basis of development of novel nanoplatform against atherosclerosis.

Factor Xa and thrombin induce endothelial progenitor cell activation. The effect of direct oral anticoagulants

Factor Xa (FXa) and thrombin exert non-hemostatic cellular actions primarily mediated through protease-activated receptors (PARs). We investigated the effect of FXa and thrombin on human late-outgrowth endothelial cells (OECs), a type of endothelial progenitor cells (EPCs), and on human umbilical vein endothelial cells (HUVECs). The effect of direct oral anticoagulants (DOACs), rivaroxaban and dabigatran, was also studied. The membrane expression of intercellular adhesion molecule-1 (ICAM-1) and the secretion of monocyte chemoattractant protein-1 (MCP-1) were used as cell activation markers. FXa and thrombin increase the ICAM-1 expression and the MCP-1 secretion on both cells, being higher on OECs. Vorapaxar, a specific PAR-1 antagonist, completely inhibits FXa-induced activation of both cells and thrombin-induced HUVEC activation, but only partially thrombin-induced OEC activation. Furthermore, thrombin-receptor activating peptide; TRAP-6, only partially activates OECs. OECs do not membrane-express PAR-4, therefore it may not be involved on thrombin-induced OEC activation. Rivaroxaban and dabigatran inhibit OEC and HUVEC activation by FXa and thrombin, respectively. Rivaroxaban enhances thrombin-induced OEC and HUVEC activation, which is completely inhibited by vorapaxar. The inhibition of OEC and HUVEC activation by vorapaxar and DOACs may represent a new pleiotropic effect of these drugs. The pathophysiological and clinical significance of our findings need to be established.

Thrombin, a Mediator of Coagulation, Inflammation, and Neurotoxicity at the Neurovascular Interface: Implications for Alzheimer's Disease

The societal burden of Alzheimer’s disease (AD) is staggering, with current estimates suggesting that 50 million people world-wide have AD. Identification of new therapeutic targets is a critical barrier to the development of disease-modifying therapies. A large body of data implicates vascular pathology and cardiovascular risk factors in the development of AD, indicating that there are likely shared pathological mediators. Inflammation plays a role in both cardiovascular disease and AD, and recent evidence has implicated elements of the coagulation system in the regulation of inflammation. In particular, the multifunctional serine protease thrombin has been found to act as a mediator of vascular dysfunction and inflammation in both the periphery and the central nervous system. In the periphery, thrombin contributes to the development of cardiovascular disease, including atherosclerosis and diabetes, by inducing endothelial dysfunction and related inflammation. In the brain, thrombin has been found to act on endothelial cells of the blood brain barrier, microglia, astrocytes, and neurons in a manner that promotes vascular dysfunction, inflammation, and neurodegeneration. Thrombin is elevated in the AD brain, and thrombin signaling has been linked to both tau and amyloid beta, pathological hallmarks of the disease. In AD mouse models, inhibiting thrombin preserves cognition and endothelial function and reduces neuroinflammation. Evidence linking atrial fibrillation with AD and dementia indicates that anticoagulant therapy may reduce the risk of dementia, with targeting thrombin shown to be particularly effective. It is time for “outside-the-box” thinking about how vascular risk factors, such as atherosclerosis and diabetes, as well as the coagulation and inflammatory pathways interact to promote increased AD risk. In this review, we present evidence that thrombin is a convergence point for AD risk factors and as such that thrombin-based therapeutics could target multiple points of AD pathology, including neurodegeneration, vascular activation, and neuroinflammation. The urgent need for disease-modifying drugs in AD demands new thinking about disease pathogenesis and an exploration of novel drug targets, we propose that thrombin inhibition is an innovative tactic in the therapeutic battle against this devastating disease.

The Correlation of Central Serous Chorioretinopathy and Subsequent Cardiovascular Diseases of Different Types: A Population-Based Cohort Study

The aim of the present study was to survey the relationship between central serous chorioretinopathy (CSC) and several cardiovascular diseases (CVDs) with different severities using the National Health Insurance Research Database. A retrospective cohort study was conducted. Subjects with CSC were enrolled according to the relevant diagnostic codes, and an age- and gender-matched population was used as the control group with a 1:4 ratio. The main outcome being considered was the development of CVD after CSC exposure. Cox proportional hazard regression was applied to calculate the adjusted hazard ratio (aHR) of CSC and CVD of different types. A total of 2865 patients that were diagnosed with CSC were enrolled in the study group, while another 11,460 non-CSC subjects were selected as the control group. There were 171 events of CVD which occurred in the study group, while another 557 cases were found in the control group. No significant differences were observed among the CVD cases between the study and control group, whether they had an acute or chronic form, according to the aHR. In the subgroup analysis, there was a significantly higher risk of CVD development in the male population aged from 40 to 59 years (aHR: 1.351, confidence interval (CI): 1.063–1.716), which was mainly due to the higher risk of mild CVD (aHR: 1.391, CI: 1.062–1.822). On the contrary, there was no significant difference in CVD development in any of the age subgroups of the female population. In conclusion, the existence of CSC is correlated with a higher rate of chronic CVD occurrence in the middle-aged male population.

Protein Kinase Cθ Via Activating Transcription Factor 2-Mediated CD36 Expression and Foam Cell Formation of Ly6Chi Cells Contributes to Atherosclerosis

BACKGROUND

Although the role of thrombin in atherothrombosis is well studied, its role in the pathogenesis of diet-induced atherosclerosis is not known.

METHODS

Using a mouse model of diet-induced atherosclerosis and molecular biological approaches, here we have explored the role of thrombin and its G protein-coupled receptor signaling in diet-induced atherosclerosis.

RESULTS

In exploring the role of G protein-coupled receptor signaling in atherogenesis, we found that thrombin triggers foam cell formation via inducing CD36 expression, and these events require Par1-mediated Gα12-Pyk2-Gab1-protein kinase C (PKC)θ-dependent ATF2 activation. Genetic deletion of PKCθ in apolipoprotein E (ApoE)^-/- mice reduced Western diet-induced plaque formation. Furthermore, thrombin induced Pyk2, Gab1, PKCθ, and ATF2 phosphorylation, CD36 expression, and foam cell formation in peritoneal macrophages of ApoE^-/- mice. In contrast, thrombin only stimulated Pyk2 and Gab1 but not ATF2 phosphorylation or its target gene CD36 expression in the peritoneal macrophages of ApoE^-/-:PKCθ^-/- mice, and it had no effect on foam cell formation. In addition, the aortic root cross-sections of Western diet-fed ApoE^-/- mice showed increased Pyk2, Gab1, PKCθ, and ATF2 phosphorylation and CD36 expression as compared with ApoE^-/-:PKCθ^-/- mice. Furthermore, although the monocytes from peripheral blood and the aorta of Western diet-fed ApoE^-/- mice were found to contain more of Ly6C^hi cells than Ly6C^lo cells, the monocytes from Western diet-fed ApoE^-/-:PKCθ^-/- mice were found to contain more Ly6C^lo cells than Ly6C^hi cells. It is interesting to note that the Ly6C^hi cells showed higher CD36 expression with enhanced capacity to form foam cells as compared with Ly6C^lo cells.

CONCLUSIONS

These findings reveal for the first time that thrombin-mediated Par1-Gα12 signaling via targeting Pyk2-Gab1-PKCθ-ATF2-dependent CD36 expression might be playing a crucial role in diet-induced atherogenesis.

Rapid and reagentless detection of thrombin in clinic samples via microfluidic aptasensors with multiple target-binding sites

A reusable and straightforward aptasensor with the implementation of open-ended porous silicon (OEPSi) membranes was introduced for thrombin detection. When passing through the nanochannels of OEPSi integrated in a microfluidic cell, thrombin in sample solution could be captured by thrombin-binding aptamers (TBA) immobilized along the inner walls. The formation of thrombin-aptamer complex causes refractive index changes which can be measured by reflective interferometric Fourier transform spectroscopy (RIFTS). And this flow-through configuration with OEPSi has proven more efficient in capturing thrombin than the flow-over configuration with closed-ended PSi. For higher sensitivity, we investigated how the pore size, ionic strength, pH and aptamers affected the thrombin-aptamer interaction in nanopores. Under optimized conditions, the limits of detection (LOD) for thrombin detection in the buffer and serum were ∼6.70 nM and ∼8.21 nM respectively and a wide linear detection range (10-1000 nM) was observed. More importantly, this work reveals the sensitivity of the label-free biosensor can be significantly improved by attaching newly designed aptamers with two thrombin-binding sites. This phenomenon also indicates the potential of aptamer probes in adjusting effective pore size and enhancing the interaction between aptamers and targets through meticulous sequence design. Furthermore, the proposed strategy has been applied in thrombin detection in clinic samples successfully, which was verified by Enzyme-Linked Immunosorbent Assays (ELISA).

Baicalin Protects against Thrombin-Induced Cell Injury in Human Umbilical Vein Endothelial Cells

Thrombin plays a pivotal role in the pathogenesis of atherosclerosis. Baicalin, an active flavonoid compound, was shown to attenuate the development of atherosclerosis, but the mechanism remains elusive. In the present study, the role and mechanism of baicalin in thrombin-induced cell injury was investigated in human umbilical vein endothelial cells (HUVECs). Our results showed that baicalin significantly reduced thrombin-induced apoptosis of HUVECs. Additional experiments showed that baicalin inhibited thrombin-induced NF-κB activation and PAR-1 expression. In addition, baicalin decreased thrombin-induced PAR-1 expression by inhibiting ERK pathway. These results indicated that baicalin has protective effects on thrombin-induced cell injury in HUVECs possibly through inhibition of PAR-1 expression and its downstream NF-κB activation, which was mediated by ERK1/2 activation.

Bimodal fluorogenic sensing of matrix proteolytic signatures in lung cancer

Optical biosensing based on the activation of fluorescent reporters offers a powerful methodology for the real-time molecular interrogation of pathology. Here we report a first-in-class, bimodal fluorescent reporter strategy for the simultaneous and highly specific detection of two independent proteases (thrombin and matrix metalloproteases (MMPs)) pivotal in the fibroproliferative process surrounding lung cancer, based on a dual, multiplexing, peptide FRET system. This sophisticated synthetic smartprobe, with a molecular weight of 6 kDa, contains two independent fluorophores and quenchers that generate photonic signatures at two specific wavelengths upon activation by target enzymes within human lung cancer tissue.

Low molecule weight fucoidan mitigates atherosclerosis in ApoE (-/-) mouse model through activating multiple signal pathway

Atherosclerosis (AS) is a chronic inflammatory disease, and many factors are implicated in its progression. This work aims to study the preventive effects and the regulatory mechanism of low-molecular-weight fucoidan (LMWF), which is obtained from Saccharina japonica, on the development of AS. Serum biochemical indices and pathological analyses were determined via ELISA, hematoxylin and eosin (HE) and Oil Red O staining. These results indicated that LMWF ameliorated areas with atherosclerotic lesions and had a significant antioxidant effect. Anticoagulant assays showed that LMWF might serve as a potential anticoagulation drug for inhibiting the formation of atherothrombosis. Double immunofluorescence staining illustrated that LMWF inhibited both SMC proliferation and migration and macrophage formation and differentiation. A molecular biology experiment showed that LMWF exhibited an apparent regulatory effect on various signaling pathways. In conclusion, our results revealed that LMWF mitigated AS in the ApoE (-/-) mouse model by activating multiple signal pathways.

Cinnamaldehyde attenuates atherosclerosis via targeting the IκB/NF-κB signaling pathway in high fat diet-induced ApoE−/− mice

Cinnamaldehyde is a flavor isolated from the bark of Cinnamomum cassia Presl and exerts anti-inflammation effects in various diseases.

The role of thrombin in central nervous system activity and stroke

Background

Thrombin is a key factor of hemostasis, mediating the conversion of fibrinogen into fibrin. Along with prothrombin, of which thrombin is the active derivative, it has been found locally expressed in the central nervous system. This article aims to describe the role of thrombin in the normal functioning of the central nervous system and stroke.

Methods

In this mini-review, the specialized databases Medscape, PubMed, and Web of Science, from the years 2003–2018, were used to find relevant documents by using MeSH terms: “thrombin” and “stroke”.

Results

Prothrombin and thrombin influence neural development, protection and regeneration, thrombin being a relatively strong regulating factor of brain function. However, high levels of thrombin are detrimental to neuronal health, and cause atherosclerotic plaque development and instability - a leading cause of cerebral infarction. In stroke, thrombin promotes direct cellular toxicity, vascular disruption, oxidative stress and inflammatory response. There is a direct correlation between thrombin activity in the affected brain hemisphere and the infarction volume. Direct acting thrombin inhibitors, like dabigatran, significantly decrease the risk of ischemic stroke.

Conclusion

Further studies on the correlation between thrombin levels, generation and activity and the risk and recurrence of ischemic cerebral stroke should give new insight on this association, resulting in an optimized practical therapeutic approach.

Impaired glucose metabolism is associated with increased thrombin generation potential in patients undergoing angioplasty and stenting

Background

As a strong platelet agonist on the one hand and key molecule in plasmatic coagulation on the other hand, thrombin connects primary and secondary hemostasis. Thrombin generation potential reflects the individual capacity to generate thrombin, and has been associated with the occurrence of thromboembolic events. In the current study, we sought to identify predictors of thrombin generation potential in patients undergoing angioplasty and stenting for atherosclerotic cardiovascular disease.

Methods

Peak thrombin generation potential and area under the curve (AUC) of thrombin generation potential were determined with a commercially available assay in 315 patients on dual antiplatelet therapy 1 day after percutaneous intervention, and in 100 healthy individuals without cardiovascular disease.

Results

Median (interquartile range) peak thrombin generation potential and AUC of thrombin generation potential in the study cohort (n = 315) were significantly higher than in healthy individuals (n = 100) without cardiovascular disease (peak thrombin generation potential: 445.4 nM [354.5–551.8 nM] vs. 174.5 nM [141.2–261.2 nM]; AUC of thrombin generation potential: 5262.7 nM thrombin [4806.6–5756.9 nM thrombin] vs. 3405.2 nM thrombin [3043.6–3747.3 nM thrombin]; both p < 0.001). In patients undergoing angioplasty and stenting, hemoglobin A1c (HbA1c) was the only variable that was independently associated with both, peak thrombin generation potential and AUC of thrombin generation potential (both p ≤ 0.007). In contrast, platelet count and high-sensitivity C-reactive protein were only associated with peak thrombin generation potential, and body mass index and serum creatinine were only associated with AUC of thrombin generation potential after adjustment for covariates by multivariate linear regression analyses (all p < 0.05). Patients with HbA1c ≥ 6% had significantly higher peak thrombin generation potential and AUC of thrombin generation potential than patients with HbA1c < 6% (peak thrombin generation potential: 476.9 nM [385.8–577.9 nM] vs. 423.9 nM [335.8–529.5 nM], p = 0.002; AUC of thrombin generation potential: 5371.8 nM thrombin [4903 – 5899 nM thrombin] vs. 5172.5 nM thrombin [4731.8–5664.7 nM thrombin], p = 0.01). HbA1c ≥ 6% remained independently associated with both parameters of thrombin generation potential after multivariate linear regression analyses (both p ≤ 0.02).

Conclusions

Impaired glucose metabolism is associated with increased thrombin generation potential in patients undergoing angioplasty and stenting for cardiovascular disease.

Pleiotropic effects of the hemostatic system

Atherothrombosis is characterized by the inflammatory process of atherosclerosis combined with a hypercoagulable state leading to superimposed thrombus formation. In atherosclerotic plaques, cell signaling can occur via protease-activated receptors (PARs), four of which have been identified so far (PAR1-PAR4). Proteases that are able to activate PARs can be produced systemically, but also at the sites of lesions, and they include thrombin and activated factor X. After PAR activation, downstream signaling can lead to both proinflammatory effects and a hypercoagulable state. Which specific effect occurs depends on the type of protease and activated PAR, and the site of activation. Hypercoagulable effects are mainly exerted through PAR1 and PAR4, whereas proinflammatory responses are mostly seen after PAR1 and PAR2 activation. PAR signaling pathways contribute to atherothrombosis, suggesting that inhibition of these pathways possibly prevents cardiovascular events based on this pathophysiological mechanism. In this review, we highlight the pathways by which PAR activation leads to proinflammatory responses and a hypercoagulable state. Furthermore, we give an overview of potential pharmacological treatment targets that promote vascular protection.

Protease-activated receptor 1 inhibits cholesterol efflux and promotes atherogenesis via cullin 3-mediated degradation of the ABCA1 transporter

Although signaling of thrombin via its receptor protease-activated receptor 1 (Par1) is known to occur in atherothrombosis, its link to the actual pathogenesis of this condition is less clear. To better understand the role of thrombin-Par1 signaling in atherosclerosis, here we have studied their effects on cellular cholesterol efflux in mice. We found that by activating Par1 and cullin 3-mediated ubiquitination and degradation of ABC subfamily A member 1 (ABCA1), thrombin inhibits cholesterol efflux in both murine macrophages and smooth muscle cells. Moreover, disruption of the Par1 gene rescued ABCA1 from Western diet-induced ubiquitination and degradation and restored cholesterol efflux in apolipoprotein E-deficient (ApoE^-/-) mice. Similarly, the Par1 deletion diminished diet-induced atherosclerotic lesions in the ApoE^-/- mice. These observations for the first time indicate a role for thrombin-Par1 signaling in the pathogenesis of diet-induced atherosclerosis. We identify cullin 3 as a cullin-RING ubiquitin E3 ligase that mediates ABCA1 ubiquitination and degradation and thereby inhibits cholesterol efflux. Furthermore, compared with peripheral blood mononuclear cells (PBMCs) from ApoE^-/- mice, the PBMCs from ApoE^-/-:Par1^-/- mice exhibited decreased trafficking to inflamed arteries of Western diet-fed ApoE^-/- mice. This finding suggested that besides inhibiting cholesterol efflux, thrombin-Par1 signaling also plays a role in the recruitment of leukocytes during diet-induced atherogenesis. Based on these findings, we conclude that thrombin-Par1 signaling appears to contribute to the pathogenesis of atherosclerosis by impairing cholesterol efflux from cells and by recruiting leukocytes to arteries.

Novel Direct Anticoagulants and Atherosclerosis

Coagulation factors can affect cellular processes that include inflammatory signaling by acting on endothelial protease activated receptors, vascular smooth muscle and inflammatory cells beyond the coagulation cascade. This is important in the pathogenesis of atherosclerosis. Accordingly, experimental data points to beneficial effects of coagulation protease inhibitors on the attenuation of atherosclerosis progression in animal models. However, available clinical data do not support the use of anticoagulants as an add-on treatment of atherosclerosis. New clinical studies are needed with a better selection of patients to clarify the role of novel direct anticoagulants in the management of atherosclerosis.

Current and future antiplatelet therapies: emphasis on preserving haemostasis

Antiplatelet drugs, such as aspirin, P2Y₁₂ antagonists, and glycoprotein (GP) IIb/IIIa inhibitors, have proved to be successful in reducing the morbidity and mortality associated with arterial thrombosis. These agents are, therefore, the cornerstone of therapy for patients with acute coronary syndromes. However, these drugs all carry an inherent risk of bleeding, which is associated with adverse cardiovascular outcomes and mortality. Thus, the potential benefits of more potent, conventional antiplatelet drugs are likely be offset by the increased risk of bleeding. Data from experiments in vivo have highlighted potentially important differences between haemostasis and thrombosis, raising the prospect of developing new antiplatelet drugs that are not associated with bleeding. Indeed, in preclinical studies, several novel antiplatelet therapies that seem to inhibit thrombosis while maintaining haemostasis have been identified. These agents include inhibitors of phosphatidylinositol 3-kinase-β (PI3Kβ), protein disulfide-isomerase, activated GPIIb/IIIa, GPIIb/IIIa outside-in signalling, protease-activated receptors, and platelet GPVI-mediated adhesion pathways. In this Review, we discuss how a therapeutic ceiling has been reached with existing antiplatelet drugs, whereby increased potency is offset by elevated bleeding risk. The latest advances in our understanding of thrombus formation have informed the development of new antiplatelet drugs that are potentially safer than currently available therapies.

Association of FV G1691A Polymorphism but not A4070G With Coronary Artery Disease

Coronary artery disease (CAD) is one of the chief causes of death in the world. Several hypotheses have been promoted as for the origin of the disease, among which are genetic predispositions and/or environmental factors. The aim of this study was to determine the effect of factor V (FV) gene polymorphisms (Leiden, G1691A [FVL] and HR2 A4070G) and to analyze their association with traditional risk factors in assessing the risk of CAD. Our study population included 200 Tunisian patients with symptomatic CAD and a control group of 300 participants matched for age and sex. All participants were genotyped for the FVL and HR2 polymorphisms. Multivariate logistic regression was applied to analyze independent factors associated with the risk of CAD. Our analysis showed that the FVL A allele frequency (P < 10^–3, odds ratio [OR] = 2.81, 95% confidence interval [CI] = 1.6-4.9) and GA genotype (P < 10^–3, OR = 4.03, 95% CI = 2.1-7.6) are significantly more prevalent among patients with CAD compared to those controls and may be predisposing to CAD. We further found that the FVL mutation is an independent risk factor whose effect is not modified by other factors (smoking, diabetes, hypertension, dyslipidemia, and a family history of CAD) in increasing the risk of the disease. However, analysis of FV HR2 variation does not show any statistically significant association with CAD. The FVL polymorphism may be an independent risk factor for CAD. However, further investigations on these polymorphisms and their possible synergisms with traditional risk factors for CAD could help to ascertain better predictability for CAD susceptibility.

Antiinflammatory effects of aspirin in ACS: relevant to its cardio coronary actions?

Vascular injury in acute coronary syndromes (ACS) involves a complex cross-talk between inflammatory mediators, platelets and thrombosis, where the interaction between platelets and coagulation factors (e. g. thrombin) is a central link between thrombosis and inflammation. In ACS, aspirin at antiplatelet doses exhibits anti-inflammatory effects as seen from the decrease in inflammation markers such as CRP, M-CSF, MCP-1 and others. These actions probably occur subsequent to inhibition of platelet COX-1-dependent thromboxane formation and its action as a multipotent autocrine and paracrine agent. This likely involves inhibition of thrombin formation as well as inhibition of secondary pro-inflammatory mediators, such as sphingosine-1-phosphate. Experimental and limited clinical data additionally suggest antiinflammatory effects of aspirin independent of its antiplatelet action. For example, aspirin at antiplatelet doses might acetylate COX-2 in vascular cells, directing the activity of the enzyme into a 15-lipoxygenase which by transcellular metabolism results in the formation of 15-epi-lipoxin (‘aspirin-triggered lipoxin’), an antiinflammatory mediator. Furthermore, aspirin stimulates eNOS via lysine-acetylation, eventually resulting in induction of heme oxygenase (HO-1), which improves the antioxidative potential of vascular cells. All of these effects have been seen at antiplatelet doses of 100–300 mg/day, equivalent to peak plasma levels of 10–30 μM. Many more potentially antiinflammatory mechanisms of aspirin have been described, mostly salicy-late-related, at low to medium millimolar concentrations and, therefore, are of minor clinical interest. Altogether, there is a wealth of data supporting antiiflammatory effects of aspirin in ACS, but studies generating direct evidence for antiinflammatory effects in ACS remain to be done.

The utility of coagulation activity for prediction of risk of mortality and cardiovascular events in guideline-treated myocardial infarction patients

BACKGROUND

Despite improved treatment of myocardial infarction (MI), real-world patients still suffer substantial risk for subsequent cardiovascular events. Little is known about coagulation activity shortly after MI and whether coagulation activity markers may identify patients at increased risk despite contemporary treatment.

OBJECTIVE

To evaluate D-dimer concentration and thrombin generation potential shortly after discharge after MI and evaluate if these markers could predict the risk of future cardiovascular and bleeding events.

METHODS

Unselected MI patients (n = 421) were included in the observational REBUS study (NCT01102933) and followed for two years. D-dimer concentrations, thrombin peak, and endogenous thrombin potential (ETP) were analyzed at inclusion (3-5 days after MI) and at early follow-up (after 2-3 weeks).

RESULTS

Seventy-five patients (17.8%) experienced the composite endpoint (all-cause death, MI, congestive heart failure, or all-cause stroke), and 31 patients (7.4%) experienced a clinically relevant bleeding event. D-dimer concentrations at early follow-up were associated with the composite endpoint (HR [per SD increase] 1.51 [95% CI 1.22-1.87]) and with clinically relevant bleeding (HR [per SD increase] 1.80 [95% CI 1.32-2.44]). Thrombin generation potential was not significantly associated with either the composite endpoint or with clinically relevant bleeding. Higher thrombin peak and ETP at early follow-up were both inversely associated with stroke (HR [per SD increase] 0.50 [95% CI 0.30-0.81] and 0.43 [95% CI 0.22-0.83], respectively).

CONCLUSION

In unselected MI patients treated according to contemporary guidelines, D-dimer measurements may identify patients at increased risk of new cardiovascular and bleeding events. The inverse association of thrombin generation potential and risk of stroke has to be further investigated.