Antithrombotic properties of aspirin and resistance to aspirin: beyond strictly antiplatelet actions

The role of bone marrow-derived cells in venous thromboembolism

Venous thrombosis is a life-threatening condition with high morbidity and mortality. Abnormal functioning of different cells in the blood is an integral part of its pathogenesis. In this review, we describe the contribution of bone marrow-derived cells to the development of this debilitating disease. We present both epidemiological and clinical data demonstrating involvement of various cell types in venous thrombosis, and discuss potential mechanisms underlying these effects. Modern concepts including recently discovered new paradigms in thrombosis, such as neutrophil extracellular traps, mast cells, and polyphosphate, are summarized.

Antithrombotic Therapy in Patients with Recent Stroke and Atrial Fibrillation

:

Atrial fibrillation (AF) is a common arrhythmia which carries a significant risk of stroke. Secondary prevention, particularly in the acute phase of stroke with anti-thrombotic therapy, has not been validated. The aim of this review is to evaluate the available evidence on the use of antithrombotic therapy in patients with recent stroke who have AF, and suggest a treatment algorithm for the various time points, taking into account both the bleeding and thrombosis risks posed at each stage.

A Brief Review of Cardiovascular Diseases, Associated Risk Factors and Current Treatment Regimes

Cardiovascular diseases (CVDs) are the leading cause of premature death and disability in humans and their incidence is on the rise globally. Given their substantial contribution towards the escalating costs of health care, CVDs also generate a high socio-economic burden in the general population. The underlying pathogenesis and progression associated with nearly all CVDs are predominantly of atherosclerotic origin that leads to the development of coronary artery disease, cerebrovascular disease, venous thromboembolism and, peripheral vascular disease, subsequently causing myocardial infarction, cardiac arrhythmias or stroke. The aetiological risk factors leading to the onset of CVDs are well recognized and include hyperlipidaemia, hypertension, diabetes, obesity, smoking and, lack of physical activity. They collectively represent more than 90% of the CVD risks in all epidemiological studies. Despite high fatality rate of CVDs, the identification and careful prevention of the underlying risk factors can significantly reduce the global epidemic of CVDs. Beside making favorable lifestyle modifications, primary regimes for the prevention and treatment of CVDs include lipid-lowering drugs, antihypertensives, antiplatelet and anticoagulation therapies. Despite their effectiveness, significant gaps in the treatment of CVDs remain. In this review, we discuss the epidemiology and pathology of the major CVDs that are prevalent globally. We also determine the contribution of well-recognized risk factors towards the development of CVDs and the prevention strategies. In the end, therapies for the control and treatment of CVDs are discussed.

Identification of cryptotanshinone from Tongmai to inhibit thrombosis in zebrafish via regulating oxidative stress and coagulation cascade

BACKGROUND

Thromboembolic events are leading causes of mortality and morbidity all over the world. Tongmai (TM) is a botanical drug with valid clinical efficacy and safety in the management of thrombosis and ischemic cardiovascular diseases, however, its active compounds and underlying mechanism are largely unclear.

PURPOSE

To investigate the endogenous effects, therapeutic mechanism and active compounds of TM in thrombus formation.

STUDY DESIGN

Combined with transgenic zebrafish models and high-content imaging system, this study evaluated the endogenous antithrombotic effects of TM and screened for the active compounds.

METHODS

The PHZ-induced thrombotic model in erythrocytes or platelets labeled transgenic zebrafish were established, to dynamically evaluate the antithrombotic effects of TM. The oxidative damage levels were analyzed by specific fluorescent probes, and the expression levels of key factors in coagulation cascades and platelet activation were examined by QPCR. TM were dissected into fractions by reverse phase chromatography and subsequently screened for their antithrombotic effects in the transgenic fish models. The compounds of the active TM fraction were then analyzed by UPLC-Q-TOF analysis and further verified for their antithrombotic effects and mechanisms.

RESULTS

In PHZ-induced zebrafish thrombotic model, TM incubation markedly increased cardiac blood flow, decreased peripheral erythrocytes aggregation, and recovered peripheral platelet circulation. Besides, the levels of oxidative stress and lipid peroxidation were increased in the PHZ-induced thrombotic fish, which were greatly decreased by TM treatment. Moreover, TM significantly reduced the expression of coagulation factor II (thrombin) and the downstream fibrinogen. In order to identify the active compounds of TM, four fractions were separated from the extract by reverse phase chromatography, which were subsequently screened for their antithrombotic effects in the fish model. As a result, fraction 4 showed the strongest effect in inhibiting thrombosis. Finally, through UPLC-Q-TOF analysis and endogenous screening, cryptotanshione was identified as the main active compound with antithrombotic effects.

CONCLUSION

Our study demonstrated the endogenous antithrombotic effects of TM, which is possibly mediated by inhibiting oxidative stress and coagulation cascade. Cryptotanshione was identified as a major compound with antithrombotic activity and is a promising candidate for novel antithrombotic therapy.

Synergistic influence of rivaroxaban on inflammation and coagulation biomarkers in patients with coronary artery disease and peripheral artery disease on aspirin therapy

COMPASS study demonstrated efficacy of dual pathway inhibition with 2.5 mg twice daily rivaroxaban and aspirin in patients with polyvascular disease (coronary artery disease, peripheral arterial disease or both), the underlying mechanism of which is not clearly understood. In this Phase IV, prospective, open-label and randomized study, we hypothesize that treatment with rivaroxaban is associated with a reduction in platelet activation and aggregation, inflammation and coagulation markers. 30 patients will be randomly treated with aspirin (81 mg q.d.) or aspirin plus rivaroxaban (2.5 mg b.i.d.) for 12 weeks. Platelet aggregation, platelet activation and inflammation markers, thrombin generation kinetics and tissue factor-induced platelet-fibrin clot strength will be measured at baseline, and 4 and 12 weeks after randomization. Trial registration number: NCT04059679.

Combination Antiplatelet and Oral Anticoagulant Therapy in Patients With Coronary and Peripheral Artery Disease

Antiplatelet therapy is the mainstay for the treatment of acute and chronic arterial disease involving the coronary and peripheral beds. However, questions remain about optimal antithrombotic therapy for long-term treatment of chronic vascular disease. The observation that dual antiplatelet therapy with acetylsalicylic acid and clopidogrel was associated with lower thrombotic event rates than acetylsalicylic acid monotherapy in patients with acute coronary syndromes and those undergoing percutaneous coronary intervention changed the treatment paradigm. Moreover, the demonstration that more pharmacodynamically potent P2Y₁₂ inhibitors than clopidogrel were associated with fewer thrombotic event occurrences further solidified the dual antiplatelet therapy approach. However, recurrent thrombotic events occur in ≈1 in 10 patients in the first year following an acute coronary syndrome event, despite treatment with the most potent P2Y₁₂ inhibitors, a limitation that has stimulated interest in exploring the efficacy and safety of approaches using anticoagulants on top of antiplatelet therapy. These investigations have included treatment with very-low-dose oral anticoagulation, and even its replacement of acetylsalicylic acid in the presence of a P2Y₁₂ inhibitor, in patients stabilized after an acute coronary syndrome event. Recent basic and translational studies have suggested noncanonical effects of coagulation factor inhibition that may further modulate clinical benefits. This in-depth review will discuss developments in our understanding of the roles that platelets and coagulation factors play in atherothrombosis and review the rationale and clinical evidence for combining antiplatelet and oral anticoagulant therapy in patients with coronary and peripheral artery disease.

Thromboelastography parameters in Italian pregnant women: do antithrombotic drugs change reference values?

This study was carried out to explore hemostasis modifications occurring in pregnant women and thromboelastography profiles in those taking antithrombotic drugs. An exploratory study was carried out in the period from March 2017 to May 2018. Caucasian women from Southern Italy were recruited during a routine obstetric assessment. Participants were divided into four groups: T1 (gestational week <14 weeks), T2 (14–28 weeks), T3 (29–42 weeks) and T4 in the postpartum period. We investigated thromboelastography profile in 19 and 5 women administered with low-molecular-weight heparin or low-dose aspirin, respectively. “MA” value observed in the T1 group was significantly greater than that observed in the T3 and the T4 groups, while “K” in the T1 group was significantly longer than that in the T3 and the T4 groups, indicating a gradual development of a prothrombotic state (in all cases Mann-Whitney U test, p<0.05). Significant differences within “R” were observed between the T2 and the T3 and between the T3 and the T4 (“R” parameter) (Mann-Whitney U test, p<0.05). “LY30” parameter resulted to be significantly higher in the T1 group (Mann-Whitney U test, p=0.01) compared with the T4 one, indicating fibrinolysis decreases throughout pregnancy and until post partum. No significant variations were found in women administered with prophylactic doses of low-molecular-weight heparin. Significantly higher fibrinolysis (p<0.01) was observed for “LY30” parameter in women taking low-dose aspirin versus women not taking any treatments. Our data contribute to better interpret thromboelastography profile in the context of peripartum complications, which are often unpredictable and need prompt therapies.

Aspirin and its pleiotropic application

Aspirin (acetylsalicylic acid), the oldest synthetic drug, was originally used as an anti-inflammatory medication. Being an irreversible inhibitor of COX (prostaglandin-endoperoxide synthase) enzymes that produce precursors for prostaglandins and thromboxanes, it has gradually found several other applications. Sometimes these applications are unrelated to its original purpose for example its use as an anticoagulant. Applications such as these have opened opportunities for new treatments. In this case, it has been tested in patients with cardiovascular disease to reduce the risk of myocardial infarct. Its function as an anticoagulant has also been explored in the prophylaxis and treatment of pre-eclampsia, where due to its anti-inflammatory properties, aspirin intake may be used to reduce the risk of colorectal cancer. It is important to always consider both the risks and benefits of aspirin's application. This is especially important for proposed use in the prevention and treatment of neurologic ailments like Alzheimer's disease, or in the prophylaxis of myocardial infarct. In such cases, the decision if aspirin should be applied, and at what dose may be guided by specific molecular markers. In this revived paper, the pleiotropic application of aspirin is summarized.

Platelet count, aspirin use, and characteristics of host inflammatory responses in colorectal cancer

Background

Platelets not only contribute to hemostasis but also to the regulation of inflammatory reactions and cancer pathogenesis. We hypothesized that blood platelet count would be associated with systemic inflammation, the densities of tumor infiltrating immune cells, and survival in colorectal cancer (CRC), and these relationships could be altered by aspirin use.

Methods

We measured blood platelet count in a cohort of 356 CRC patients and analyzed its relationships with tumor and patient characteristics including aspirin use, markers of systemic inflammation (modified Glasgow Prognostic Score, mGPS; serum levels of CRP, albumin, and 13 cytokines), blood hemoglobin levels, five types of tumor infiltrating immune cells (CD3, CD8, FoxP3, Neutrophil elastase, mast cell tryptase), and survival.

Results

Platelet count inversely correlated with blood hemoglobin levels (p < 0.001) and positively correlated with serum levels of CRP and multiple cytokines including IL-1RA, IL-4, IL-6, IL-7, IL-8, IL-12, IFNγ, and PDGF-BB (p < 0.001 for all), while aspirin use was not associated with the levels of systemic inflammatory markers. High platelet count was also associated with high mGPS (p < 0.001) but did not show statistically significant multivariable adjusted associations with the densities of tumor infiltrating immune cells. Higher platelet counts were observed in higher tumor stage (p < 0.001), but platelet count or aspirin use were not associated with patient survival.

Conclusions

High platelet count is associated with systemic inflammation in CRC. This study could not demonstrate statistically significant associations between platelet count, aspirin use, and the densities of tumor infiltrating immune cells.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1950-z) contains supplementary material, which is available to authorized users.

Petechia of the Penis: Sexual Habits or Adverse Drug Reaction?

To the best of our knowledge, we report the first case of recurring small red macules (petechia), exclusively localized on the gland secondary to fellatio in an adult man, who is on therapy with acetylsalicylic acid. No previous studies have been ever conducted on the possible onset of penis petechia after oral sex. Petechia are nonspecific cutaneous lesions appearing as circumscribed sub-epithelial hemorrhages, or appearing as small dark red or purplish spots as a result of capillaries rupture.

Bismuth Subsalicylate Coagulopathy in a Patient with Chronic Liver Disease

Bismuth subsalicylate (BSS) is the active ingredient in over-the-counter antacid and antidiarrheal medications. Coagulopathy in the setting of acetylsalicylic acid toxicity is well documented but not in setting of bismuth subsalicylate overuse. We present a case report of coagulopathy from BSS poisoning in a patient with underlying cirrhosis. The patient's high prothrombin time suggests inhibition of vitamin K-dependent coagulation factors. The patient had decreased factor V activity, which is responsible for converting prothrombin to thrombin. Patients with cirrhosis often have hypoprothrombinemia which may be exacerbated by salicylate-induced coagulopathy. Given the widespread use of BSS products, physicians should recognize coagulopathy as a possible manifestation of toxicity especially in patients with underlying liver disease.

Prothrombotic State in Atrial Fibrillation Patients With One Additional Risk Factor of the CHA2DS2-VASc Score (Beyond Sex)

BACKGROUND

It is unclear whether a prothrombotic state occurs in atrial fibrillation (AF) with low stroke risk.

METHODS

We studied 118 patients with AF with the Congestive Heart Failure, Hypertension, Age (≥ 75 years), Diabetes, Stroke/Transient Ischemic Attack/Systemic Embolism, Vascular Disease, Age (65-74 years), Sex (Female) (CHA₂DS₂-VASc) score of 1 in men or 2 in women vs 52 patients with AF with the CHA₂DS₂-VASc score of 0 in men or 1 in women. Plasma clot permeability (K_s), a measure of fibrin clot density, and clot lysis time (CLT), endogenous thrombin potential (ETP), von Willebrand factor antigen, and plasminogen activator inhibitor-1 were evaluated in nonanticoagulated subjects.

RESULTS

Patients with the CHA₂DS₂-VASc score of 1 (beyond sex), compared with those with 0, had lower K_s, prolonged CLT, increased ETP, von Willebrand factor antigen, and plasminogen activator inhibitor-1 (all P < 0.001), without any sex-dependent differences. Heart failure (odds ratio [OR]: 10.28; 95% confidence interval [CI]: 2.32-45.41), age 65-74 years (OR: 4.37; 95% CI: 1.76-10.83), and hypertension (OR: 5.03; 95% CI: 1.81-13.94) were independently associated with low K_s (the lowest quartile, ≤ 6.4 × 10^-9 cm²), whereas only age 65-74 years (OR: 3.33; 95% CI: 1.59-6.96) significantly predicted prolonged CLT (the top quartile, ≥ 108 minutes). Age 65-74 years (OR: 5.21; 95% CI: 2.12-12.80), heart failure (OR: 6.58; 95% CI: 1.49-29.06), and hypertension (OR: 4.33; 95% CI: 1.54-12.15) were independently associated with high ETP (the top quartile, ≥ 1681.3 nM × minutes).

CONCLUSIONS

A prothrombotic state (increased thrombin generation, denser fibrin clots, impaired fibrinolysis, and endothelial injury) characterizes patients with AF with 1 additional clinical stroke risk factor (beyond sex), with age 65-74 years being particularly associated with prothrombotic indices.

Hematologic variables associated with brain failure in patients with small-cell lung cancer

BACKGROUND AND PURPOSE

We sought factors associated with the development of brain metastases after treatment of small cell lung cancer (SCLC) in patients without brain involvement at diagnosis.

METHODS

We analyzed 293 patients with SCLC without brain metastases who received chemotherapy, thoracic radiation therapy (TRT), or both in 2001-2015. Pretreatment hematologic markers (platelet count, neutrophil count, lymphocyte count, neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio, and lactate dehydrogenase) and other clinical characteristics were evaluated for correlation with brain metastases-free survival (BMFS). Cutoffs were established with receiver operating characteristics curves. Factors significant in univariate analysis were used to build a multivariate Cox model for BMFS.

RESULTS

Median follow-up time was 14.3 months. Brain metastases developed in 115 patients (39%)-32% of those with low pretreatment platelet counts (PPC) (≤270 × 10⁹/L) and 46% of those with high PPC (>270 × 10⁹/L). Median BMFS time for all patients was 27.9 months. Two-year BMFS rates were worse for patients with high PPC (14.6% vs. 22.1% low, P = 0.009). High PPC was independently associated with inferior BMFS (P = 0.038), as were receipt of TRT <45 Gy and no prophylactic cranial irradiation (both P < 0.001).

CONCLUSIONS

High PPC was associated with increased rates of brain metastasis in patients with SCLC with no evidence of brain disease at diagnosis.

Clinical Significance of Acute and Serial Platelet Function Testing in Acute Ischemic Stroke

Background

We sought to investigate the clinical implications of platelet reactivity to aspirin and the variability in the platelet reactivity to aspirin during acute periods for the risk of vascular events in patients with acute ischemic stroke.

Methods and Results

This was a single‐center, prospective, observational study. The aspirin reaction unit was blindly measured at the following two times: after 3 hours of aspirin loading and on the fifth day of aspirin administration. High on‐aspirin platelet reactivity (HAPR) was defined as an aspirin reaction unit ≥550 IU. The primary outcome measure was the 1‐year composite of stroke, myocardial infarction, and vascular death. A total of 805 patients (aged 66±12 years, 61% male) were analyzed in this study. Ninety‐nine of 805 (12.3%) patients and 78 of 558 (14.0%) patients had HAPR at the time of the fifth day of aspirin administration and after 3 hours of aspirin loading measurements, respectively. Patients with HAPR than normal on‐aspirin platelet reactivity at the fifth day of aspirin administration measurement were more likely to have experienced 1‐year vascular event. HAPR at the fifth day of aspirin administration measurement was independently associated with a greater risk of experiencing 1‐year vascular event (hazard ratio, 1.84; 95% confidence interval, 1.07–3.19). Moreover, persistently HAPR substantially increased the risk of 1‐year vascular events (hazard ratio, 3.11; 95% confidence interval, 1.23–7.86).

Conclusions

These results suggest that HAPR during the acute stage of ischemic stroke increases the risk of subsequent vascular events and that serial aspirin reaction unit measurements may identify patients with acute ischemic stroke who are at a higher risk for vascular events. Additional studies are warranted to determine the appropriate treatments for patients with acute ischemic stroke with HAPR.

Thromboprophylaxis in Head and Neck Microvascular Reconstruction

Head and neck patients undergoing microvascular reconstruction are at high risk for thromboembolism. While the prevention of thromboembolism has become an essential aspect of care, within the field of microsurgery, concern for anastomotic complications have hindered the creation of an accepted regimen. The aim of this review was to evaluate the risks and benefits of prophylactic agents for thromboprophylaxis. A literature search was conducted in MEDLINE, Cochrane Library, and PubMed/NCBI databases. Articles discussing thromboprophylaxis in otolaryngology, head and neck surgery, or microvascular reconstruction were considered in the review from the past 30 years. The majority of patients undergoing microvascular surgery have multiple risk factors for thrombus formation. Several consensus guidelines exist for the prophylaxis in patients who are critically ill, undergoing surgery, or with malignancy. Significant evidence supports the routine use of mechanical means, such as early mobilization and pneumatic compression along with subcutaneous heparin. Low-molecular-weight heparin is also frequently utilized, although results are largely divided. Data on aspirin remain equivocal. Studies on microvascular failure and flap loss have demonstrated little to no association with chemoprophylaxis. The evidence for postoperative thromboprophylaxis regimens in patients undergoing head and neck free tissue transfer is variable. Multiple studies have supported the use of unfractionated heparin or low-molecular-weight heparin. There appears to be an expert consensus for the combined use of mechanical prophylactic methods and chemical prophylaxis. Prospective randomized trials are required to validate the most effective combination of chemoprophylaxis agents.

Why we should not skip aspirin in cardiovascular prevention

Since more than 20 years, aspirin is an approved and established first-line antiplatelet medication in cardiovascular prevention. This is partially due to ist unique mode of action which is not shared with any other antiplatelet agent as well by the reliability of its pharmacological efficacy: inhibition of platelet COX-1 and subsequent thromboxane formation in almost every patient. Aspirin acts synergistic with ADP-antagonists in dual antiplatelet therapy of acute coronary syndroms (ACS) and percutaneous coronary interventions (PCI) and is also approved for long-term secondary prevention. Patients with atrial fibrillation are an exception and benefit more from anticoagulants. After the introduction of the new oral anticoagulants (NOACs), i.e. direct inhibitors of factor Xa or thrombin formation, there is a renewed discussion about the role of antiplatelet agents, specifically if additional dual antiplatelet treatment is still necessary for an optimum clinical effect or whether one component, such as aspirin might be skipped in favor of other classes of oral antiplatelet agents, such as ADP-antagonists. The available data are insufficient to recommend this because of a low number of studies and a still uncertain benefit/ risk (bleeding) ratio. More research on aspirin as a chemopreventive appears also to be necessary and is going on, in particular in individuals at high-risk for vascular thrombotic diseases (diabetics, preeclampsia, venous thrombembolism).

Thrombosis and Vascular Inflammation in Diabetes: Mechanisms and Potential Therapeutic Targets

Cardiovascular disease remains the main cause of morbidity and mortality in patients with diabetes. The risk of vascular ischemia is increased in this population and outcome following an event is inferior compared to individuals with normal glucose metabolism. The reasons for the adverse vascular profile in diabetes are related to a combination of more extensive atherosclerotic disease coupled with an enhanced thrombotic environment. Long-term measures to halt the accelerated atherosclerotic process in diabetes have only partially addressed vascular pathology, while long-term antithrombotic management remains largely similar to individuals without diabetes. We address in this review the pathophysiological mechanisms responsible for atherosclerosis with special emphasis on diabetes-related pathways. We also cover the enhanced thrombotic milieu, characterized by increased platelet activation, raised activity of procoagulant proteins together with compromised function of the fibrinolytic system. Potential new therapeutic targets to reduce the risk of atherothrombosis in diabetes are explored, including alternative use of existing therapies. Special emphasis is placed on diabetes-specific therapeutic targets that have the potential to reduce vascular risk while keeping an acceptable clinical side effect profile. It is now generally acknowledged that diabetes is not a single clinical entity but a continuum of various stages of the condition with each having a different vascular risk. Therefore, we propose that future therapies aiming to reduce vascular risk in diabetes require a stratified approach with each group having a "stage-specific" vascular management strategy. This "individualized care" in diabetes may prove to be essential to improve vascular outcome in this high risk population.

Optimization and Characterization of Aspirin Encapsulated Nano-liposomes

Resistance to aspirin and its cytotoxicity significantly limits its therapeutic applications. Nano-liposomal encapsulation of aspirin can reduce its cytotoxicity. In this study, aspirin encapsulating nano-liposomes (AS-NL) was prepared and its performance in drug delivery and also cytotoxicity was evaluated. The effects of two independent variables including number of freeze/thawing cycles and concentration of aspirin on encapsulation efficiency was investigated using response surface methodology (RSM). A drug profile release was obtained by AS-NL. The concentration of cholesterol as effective for liposome stability and sodium lauryl sulfate (SLS) as a drug release facilitator was also optimized using RSM. The maximum aspirin encapsulation efficiency (41.44%) and drug release (33.92%) was obtained for 0.514 mg cholesterol and 0.007 mg SLS used for liposome formulation. The morphology and size of AS-NLs were characterized using transmission electron microscopy (TEM) and dynamic light scattering (DLS). The stability of AS-NL was evaluated by measuring the size change of nano-liposomes during 21 days using DLS analysis. The stability of AS-NL during this period was acceptable. The cytotoxicity test of AS-NL by MTT test reveals the cytotoxicity of aspirin can be reduced by using liposome encapsulation.

Role of Antiplatelet Therapy in Stroke Prevention in Patients With Atrial Fibrillation

Patients with atrial fibrillation are at increased risk of having a cardioembolic stroke. The use of oral anticoagulation is now well established to prevent strokes in patients with atrial fibrillation and a CHA2DS2-VASc (congestive heart failure, hypertension, age ≥75 years [2 points], diabetes mellitus, prior stroke/transient ischemic attack or thromboembolism [2 points], vascular disease, age 65 to 74 years, and sex category) score of greater than 1, beyond sex. However, the role of antiplatelet therapy, specifically aspirin in low-risk patients or as an alternative to oral anticoagulation, remains controversial. The most recent US guidelines conflict with the European guidelines, which do not recommend antiplatelet monotherapy for stroke prevention irrespective of stroke risk. The aim of this review is to summarize published studies that question the role of aspirin in preventing strokes associated with atrial fibrillation. Overall, aspirin is found to play a limited role in the prevention of stroke in patients with atrial fibrillation and is associated with a similar risk of hemorrhagic events compared with anticoagulants. The benefit of dual antiplatelet therapy as an alternative to oral anticoagulation requires further study.

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.

Contemporary Use of Oral Antithrombotic Agents: Focus on Dual and Triple Therapeutic Approaches

Atherosclerotic cardiovascular disease (ASCVD) represents a long-standing health care burden in most industrialized countries. Management of ASCVD is multifaceted, and utilization of antithrombotic agents is a key component of care to reduce vascular events. Minimizing thrombotic risk can be accomplished via antiplatelet or anticoagulant drugs; however, combination therapy is warranted for some indications. Although reducing thrombotic complications is important, it is equally vital to consider the safety of combination regimens. Thus clinicians must effectively balance both individualized thrombotic and bleeding risks when using this strategy. Scenarios occur in practice when determining the role for combination therapy is not clear, especially for patients with ASCVD who require both dual antiplatelet therapy plus anticoagulation. The aim of this review is to discuss the role of dual or triple antithrombotic therapies across the spectrum of thrombotic disease states. In addition to critiquing relevant research studies and evaluating key recommendations from nationally published guidelines and consensus statements involving the use of these agents, we offer practical considerations that can be utilized when managing patients with ASCVD.

Capillary Flow Rates in the Duodenum of Pediatric Ulcerative Colitis Patients Are Increased and Unrelated to Inflammation

BACKGROUND AND AIM

Inflammatory bowel diseases (IBD), including Crohn disease (CD) and ulcerative colitis (UC), are chronic pediatric disorders. Changes in vasculature are described in IBD, but these could be secondary to inflammation and the role in pathogenesis is poorly understood. Assessing circulatory changes in typically unaffected sites in IBD (eg, duodenum), when inflammation is absent, can identify vascular changes associated with pathogenesis. The aim of the study is to measure capillary flow rates in duodenal mucosa using probe-based confocal laser endomicroscopy (pCLE) during endoscopy in children with IBD.

METHODS

Images of villi with visible blood vessels obtained using pCLE were captured as video sequences. Capillary flow rate (mm/s) was calculated by dividing the distance travelled by blood cells by the duration of the sequence. Flow rates were correlated with various clinical parameters.

RESULTS

Forty-five patients (22 non-IBD, 14 CD, 9 UC) were included in the study. Duodenal capillary flow rates were significantly higher in UC patients (0.75 ± 0.07 mm/s) as compared to non-IBD (0.57 ± 0.03) and CD (0.65 ± 0.04). There was no correlation between serum hemoglobin and albumin, disease activity indices, serum inflammatory markers, and capillary flow rates in patients.

CONCLUSIONS

This pilot study shows, for the first time, increased capillary blood flow in the duodenum of UC patients that was unrelated to inflammatory markers or disease activity. Thus, early vascular changes can be assessed using pCLE during endoscopy.

Lipopolysaccharide-binding protein (LBP) reverses the amyloid state of fibrin seen in plasma of type 2 diabetics with cardiovascular co-morbidities

Type 2 diabetes (T2D) has many cardiovascular complications, including a thrombotic propensity. Many such chronic, inflammatory diseases are accompanied (and may be exacerbated, and possibly even largely caused) by amyloid fibril formation. Recognising that there are few strong genetic associations underpinning T2D, but that amyloidogenesis of amylin is closely involved, we have been seeking to understand what might trigger the disease. Serum levels of bacterial lipopolysaccharide are raised in T2D, and we recently showed that fibrin(ogen) polymerisation during blood clotting can be affected strongly by LPS. The selectivity was indicated by the regularisation of clotting by lipopolysaccharide-binding protein (LBP). Since coagulopathies are a hallmark of T2D, we wondered whether they might too be caused by LPS (and reversed by LBP). We show here, using SEM and confocal microscopy, that platelet-poor-plasma from subjects with T2D had a much greater propensity for hypercoagulability and for amyloidogenesis, and that these could both be reversed by LBP. These data imply that coagulopathies are an important feature of T2D, and may be driven by ‘hidden’ LPS. Given the prevalence of amyloid formation in the sequelae of diabetes, this opens up novel strategies for both the prevention and treatment of T2D.

Exodontia in dual antiplatelet therapy: the evidence

BACKGROUND

Haemostasis is crucial for the success of oral surgical treatment as bleeding problems can cause complications both pre- and post-operatively. Patients on antiplatelet drugs present a challenge due to their increased risk of bleeding.

AIMS

To identify a protocol for the management of oral surgery patients on dual antiplatelet therapy (aspirin and clopidogrel).

METHODS

A literature review was conducted in January 2016 of free-text and MESH searches (keywords: aspirin, clopidogrel and dental extractions) in the Cochrane Library, PubMed and CINAHL. Trial registers, professional bodies for guidelines and OpenGrey for unpublished literature were also searched. Studies were selected for appraisal after limits were applied (adult, human and English only studies) and inclusion/exclusion criteria imposed.

RESULTS

Eight studies were identified for critical appraisal using the CASP tools. These were a combination of retrospective, prospective, cohort and case control studies. Napenas et al. and Park et al. found no statistically significant risk of postoperative bleeding complications in patients on dual antiplatelet therapy. Girotra et al., Lillis et al., Omar et al. and Olmos-Carrasco et al., however, found statistically significant risk of postoperative bleeding in this group of patients, all of which can be controlled with local measures.

CONCLUSION

Patients on dual antiplatelet therapy - although at an increased risk of postoperative bleeding complications - can be managed safely with local haemostatic measures and without the need to discontinue antiplatelet therapy.

Current controversies in the use of aspirin and ticagrelor for the treatment of thrombotic events

INTRODUCTION

A P2Y₁₂ inhibitor plus aspirin is the most widely used antiplatelet strategy to prevent adverse outcomes in the setting of atherothrombotic vascular disease. Areas covered: A paucity of robust evidence for an optimal dose, gastrointestinal toxicity, ineffectiveness in high-risk patients and interactions with other antiplatelet agents, are major controversies associated with aspirin therapy. Ticagrelor is a reversibly binding oral P2Y₁₂ receptor blocker that mediates potent inhibition of adenosine diphosphate-induced platelet function. It is more effective than clopidogrel in preventing thrombotic events in acute coronary syndrome patients. The absence of a beneficial effect for ticagrelor versus clopidogrel in ACS observed in the North American subgroup of the PLATelet inhibition and patient Outcomes (PLATO) trial has been attributed to a higher concomitant aspirin dose. Expert commentary: Ongoing studies are now investigating the plausibility of removing aspirin therapy in the setting of potent P2Y₁₂ receptor blockade via ticagrelor monotherapy or replacing aspirin with an oral anticoagulant.

Clot Formation in the Presence of Acetylsalicylic Acid Leads to Increased Lysis Rates Regardless of the Chosen Thrombolysis Strategy

BACKGROUND

Patients with acute ischemic strokes frequently take an acetylsalicylic acid (ASA) premedication. We determined the impact of ASA on different thrombolysis strategies in vitro.

METHODS

For two clot types made from platelet-rich plasma (one with and one without ASA) lysis rates were measured by weight loss after 1 h for five different groups: in control group A clots were solely placed in plasma; in groups B and C clots were treated with rt-PA (60 kU/ml), and in groups D and E clots were treated with desmoteplase (DSPA; 2 µg/ml). Ultrasound (2 MHz, 0.179 W/cm2) was included in groups C and E. The fibrin mesh structures of the clots were investigated by electron microscopy.

RESULTS

For both clot types lysis rates increased significantly for all treatment strategies compared to their control group (each p < 0.001). The addition of ASA significantly increased the lysis rate in all 5 groups (each p < 0.001) and led to a ceiling effect concerning the treatment. A semiquantitative analysis of transmission electron micrographs revealed a decreased fibrin density for clots with ASA. For both clot types DSPA and ultrasound led to a significant dissolution of the fibrin mesh (both p = 0.029).

CONCLUSIONS

In vitro ASA pretreatment leads to significantly increased lysis rates due to a weaker fibrin mesh in platelet-rich plasma clots.

Pharmacogenetics in Oral Antithrombotic Therapy

Certain antithrombotic drugs exhibit high patient-to-patient variability that significantly impacts the safety and efficacy of therapy. Pharmacogenetics offers the possibility of tailoring drug treatment to patients based on individual genotypes, and this type of testing has been recommended for 2 oral antithrombotic agents, warfarin and clopidogrel, to influence use and guide dosing. Limited studies have identified polymorphisms that affect the metabolism and activity of newer oral antithrombotic drugs, without clear evidence of the clinical relevance of such polymorphisms. This article provides an overview of the current status of pharmacogenetics in oral antithrombotic therapy.

P2Y12 receptor inhibition and LPS-induced coagulation

Platelets play a major role in the complex interactions involved in blood coagulation via multiple mechanisms. As reported in this issue, Schoergenhofer et al. tested the hypothesis that platelet inhibition by prasugrel, a potent platelet P2Y12 ADP receptor antagonist, attenuates the effect of lipopolysaccharide (LPS) on the blood coagulation system in healthy human subjects. LPS, a bacterial product with potent pro-inflammatory and pro-thrombotic effects, plays a central role in sepsis. It activates monocytes and endothelial cells via Toll-like receptor (TLR) 4 and other TLRs to stimulate production of TF and other pro-coagulant molecules, chemokines and cytokines. Treatment with prasugrel did not decrease biomarkers of coagulaion. A better understanding of the relative roles of platelet and coagulation mechanisms in triggering the pro-thrombotic state may lead to more effective antithrombotic strategies.

New formulation of old aspirin for better delivery

For better use of cyclooxygenase dependent anti-inflammatory properties and mitochondrial activities of aspirin, new hydrophobic analogues of aspirin were developed and successfully encapsulated in polymeric nanoparticles (NPs). In vivo anti-inflammatory effects of these NPs using a mouse model demonstrated unique properties of an optimized aspirin analogue to inhibit production of pro-inflammatory and enrichment of anti-inflammatory cytokines.

NSAIDs and Cardiovascular Diseases: Role of Reactive Oxygen Species

Nonsteroidal anti-inflammatory drugs (NSAIDs) are the most commonly used drugs worldwide. NSAIDs are used for a variety of conditions including pain, rheumatoid arthritis, and musculoskeletal disorders. The beneficial effects of NSAIDs in reducing or relieving pain are well established, and other benefits such as reducing inflammation and anticancer effects are also documented. The undesirable side effects of NSAIDs include ulcers, internal bleeding, kidney failure, and increased risk of heart attack and stroke. Some of these side effects may be due to the oxidative stress induced by NSAIDs in different tissues. NSAIDs have been shown to induce reactive oxygen species (ROS) in different cell types including cardiac and cardiovascular related cells. Increases in ROS result in increased levels of oxidized proteins which alters key intracellular signaling pathways. One of these key pathways is apoptosis which causes cell death when significantly activated. This review discusses the relationship between NSAIDs and cardiovascular diseases (CVD) and the role of NSAID-induced ROS in CVD.

Drug-Free Platelets Can Act as Seeds for Aggregate Formation During Antiplatelet Therapy

Supplemental Digital Content is available in the text.

Objective—

Reduced antiplatelet drug efficacy occurs in conditions of increased platelet turnover, associated with increased proportions of drug-free, that is, uninhibited, platelets. Here, we detail mechanisms by which drug-free platelets promote platelet aggregation in the face of standard antiplatelet therapy.

Approach and Results—

To model standard antiplatelet therapy, platelets were treated in vitro with aspirin, the P2Y₁₂ receptor blocker prasugrel active metabolite, or aspirin plus prasugrel active metabolite. Different proportions of uninhibited platelets were then introduced. Light transmission aggregometry analysis demonstrated clear positive associations between proportions of drug-free platelets and percentage platelet aggregation in response to a range of platelet agonists. Using differential platelet labeling coupled with advanced flow cytometry and confocal imaging we found aggregates formed in mixtures of aspirin-inhibited platelets together with drug-free platelets were characterized by intermingled platelet populations. This distribution is in accordance with the ability of drug-free platelets to generate thromboxane A₂ and so drive secondary platelet activation. Conversely, aggregates formed in mixtures of prasugrel active metabolite–inhibited or aspirin plus prasugrel active metabolite–inhibited platelets together with drug-free platelets were characterized by distinct cores of drug-free platelets. This distribution is consistent with the ability of drug-free platelets to respond to the secondary activator ADP.

Conclusions—

These experiments are the first to image the interactions of inhibited and uninhibited platelets in the formation of platelet aggregates. They demonstrate that a general population of platelets can contain subpopulations that respond strikingly differently to overall stimulation of the population and so act as the seed for platelet aggregation.

Aspirin and multiple sclerosis

Aspirin is widely used to lessen the risks of cardiovascular events. Some studies suggest that patients with multiple sclerosis have an increased risk for some cardiovascular events, for example, venous thromboembolism and perhaps ischemic strokes, raising the possibility that aspirin could lessen these increased risks in this population or subgroups (patients with limited mobility and/or antiphospholipid antibodies). However, aspirin causes a small increased risk of hemorrhagic stroke, which is a concern as it could potentially worsen a compromised blood-brain barrier. Aspirin has the potential to ameliorate the disease process in multiple sclerosis (for example, by limiting some components of inflammation), but aspirin also has the potential to inhibit mitochondrial complex I activity, which is already reduced in multiple sclerosis. In an experimental setting of a cerebral ischemic lesion, aspirin promoted the proliferation and/or differentiation of oligodendrocyte precursors, raising the possibility that aspirin could facilitate remyelination efforts in multiple sclerosis. Other actions by aspirin may lead to small improvements of some symptoms (for example, lessening fatigue). Here we consider potential benefits and risks of aspirin usage by patients with multiple sclerosis.

Effects of parecoxib on analgesia benefit and blood loss following open prostatectomy: a multicentre randomized trial

Background

This multi-centre, prospective, randomized, double-blind, placebo-controlled study was designed to test the hypotheses that parecoxib improves patients’ postoperative analgesia without increasing surgical blood loss following radical open prostatectomy.

Methods

105 patients (64 ± 7 years old) were randomized to receive either parecoxib or placebo with concurrent morphine patient controlled analgesia. Cumulative opioid consumption (primary objective) and the overall benefit of analgesia score (OBAS), the modified brief pain inventory short form (m-BPI-sf), the opioid-related symptom distress scale (OR-SDS), and perioperative blood loss (secondary objectives) were assessed.

Results

In each group 48 patients received the study medication for 48 hours postoperatively. Parecoxib significantly reduced cumulative opioid consumption by 24% (43 ± 24.1 mg versus 57 ± 28 mg, mean ± SD, p=0.02), translating into improved benefit of analgesia (OBAS: 2(0/4) versus 3(1/5.25), p=0.01), pain severity (m-BPI-sf: 1(1/2) versus 2(2/3), p < 0.01) and pain interference (m-BPI-sf: 1(0/1) versus 1(1/3), p=0.001), as well as reduced opioid-related side effects (OR-SDS score: 0.3(0.075/0.51) versus 0.4(0.2/0.83), p=0.03). Blood loss was significantly higher at 24 hours following surgery in the parecoxib group (4.3 g⋅dL⁻¹ (3.6/4.9) versus (3.2 g⋅dL⁻¹ (2.4/4.95), p=0.02).

Conclusions

Following major abdominal surgery, parecoxib significantly improves patients’ perceived analgesia. Parecoxib may however increase perioperative blood loss. Further trials are needed to evaluate the effects of selective cyclooxygenase-2 inhibitors on blood loss.

Trial registration

ClinicalTrials.gov Identifier: NCT00346268

Why does aspirin decrease the risk of venous thromboembolism? On old and novel antithrombotic effects of acetyl salicylic acid

It is well established that aspirin, an irreversible inhibitor of platelet cyclooxygenase activity, is effective in secondary prevention of arterial thromboembolic events. The pooled results of the recent randomized, multicenter WARFASA and ASPIRE aspirin trials showed a 32% reduction in the rate of recurrence of venous thromboembolism (VTE) in patients receiving aspirin following VTE. These clinical data support evidence that platelets contribute to the initiation and progression of venous thrombosis and aspirin inhibits thrombin formation and thrombin-mediated coagulant reactions. In addition to the known acetylation of serine 529 residue in platelet cyclooxygenase-1, the postulated mechanisms of aspirin-induced antithrombotic actions also involve the acetylation of other proteins in blood coagulation, including fibrinogen, resulting in more efficient fibrinolysis. This review summarizes current knowledge on the aspirin-induced antithrombotic effects that potentially explain clinical studies showing reduced rates of VTE events in aspirin-treated subjects.

Aspirin for primary prevention of cardiovascular events: meta-analysis of randomized controlled trials and subgroup analysis by sex and diabetes status

OBJECTIVE

To evaluate the benefits and harms of aspirin for the primary prevention of CVD and determine whether the effects vary by sex and diabetes status.

METHODS

We searched Medline, Embase, and Cochrane databases for randomized controlled trials comparing the effects of aspirin with placebo or control in people with no pre-existing CVD. Two investigators independently extracted data and assessed the study quality. Analyses were performed using Stata version 12.

RESULTS

Fourteen trials (107,686 participants) were eligible. Aspirin was associated with reductions in major cardiovascular events (risk ratio, 0.90; 95% confidence interval, 0.85-0.95), myocardial infarction (0.86; 0.75-0.93), ischemic stroke (0.86; 0.75-0.98) and all-cause mortality (0.94; 0.89-0.99). There were also increases in hemorrhagic stroke (1.34; 1.01-1.79) and major bleeding (1.55; 1.35-1.78) with aspirin. The number needed to treat to prevent 1 major cardiovascular event over a mean follow-up of 6.8 years was 284. By comparison, the numbers needed to harm to cause 1 major bleeding is 299. In subgroup analyses, pooled results demonstrated a reduction in myocardial infarction among men (0.71; 0.59-0.85) and ischemic stroke among women (0.77; 0.63-0.93). Aspirin use was associated with a reduction (0.65; 0.51-0.82) in myocardial infarction among diabetic men. In meta-regression analyses, the results suggested that aspirin therapy might be associated with a decrease in stroke among diabetic women and a decrease in MI among diabetic men and risk reductions achieved with low doses (75 mg/day) were as large as those obtained with higher doses (650 mg/day).

CONCLUSIONS

The use of low-dose aspirin was beneficial for primary prevention of CVD and the decision regarding an aspirin regimen should be made on an individual patient basis. The effects of aspirin therapy varied by sex and diabetes status. A clear benefit of aspirin in the primary prevention of CVD in people with diabetes needs more trials.

Genotype-guided use of oral antithrombotic therapy: a pharmacoeconomic perspective

Pharmacogenomics focuses on tailoring therapy to the individual as opposed to the historical model of fitting the individual to the therapy, and it offers the potential to maximize medication efficacy while reducing adverse events. By its very nature, personalized medicine is conducive to a patient-centered care model. Oral antithrombotics as a class could benefit immensely from this type of approach because an imbalance of safety and efficacy in either direction can yield deadly consequences. Since the current healthcare climate in the USA requires thoughtful allocation of resources, pharmacoeconomic analysis has become critical for all stakeholders, and the adoption of new technologies hinges upon economic impact. This article summarizes the current state of genetics in oral antithrombotic therapy, including clinical relevance as well as cost-effectiveness from a US healthcare system perspective, and provides insight into the future of pharmacogenomics in treating and preventing thromboembolic disorders.

Comparison of protein acetyltransferase action of CRTAase with the prototypes of HAT

Our laboratory is credited for the discovery of enzymatic acetylation of protein, a phenomenon unknown till we identified an enzyme termed acetoxy drug: protein transacetylase (TAase), catalyzing the transfer of acetyl group from polyphenolic acetates to receptor proteins (RP). Later, TAase was identified as calreticulin (CR), an endoplasmic reticulum luminal protein. CR was termed calreticulin transacetylase (CRTAase). Our persistent study revealed that CR like other families of histone acetyltransferases (HATs) such as p300, Rtt109, PCAF, and ESA1, undergoes autoacetylation. The autoacetylated CR was characterized as a stable intermediate in CRTAase catalyzed protein acetylation, and similar was the case with ESA1. The autoacetylation of CR like that of HATs was found to enhance protein-protein interaction. CR like HAT-1, CBP, and p300 mediated the acylation of RP utilizing acetyl CoA and propionyl CoA as the substrates. The similarities between CRTAase and HATs in mediating protein acylation are highlighted in this review.