Gender-based differences in platelet function and platelet reactivity to P2Y12 inhibitors

Sex-Based Outcomes of Dual-Antiplatelet Therapy After Percutaneous Coronary Intervention: A Pairwise and Network Meta-Analysis

BACKGROUND

Although dual antiplatelet therapy (DAPT) improves the outcomes of patients undergoing percutaneous coronary intervention (PCI), sex-specific differences in efficacy and safety of DAPT remain unresolved. We compared sex differences for DAPT outcomes and DAPT durations (1-3 months [short-term], 6 months [mid-term], and >12 months [extended] vs. 12 months).

METHODS

We searched databases through 31 December 2023 for trials reporting DAPT after PCI. The endpoints were major adverse cardiovascular and cerebrovascular events (MACCE), net adverse clinical and cerebrovascular events (NACCE), and any bleeding. Extracted data were pooled in a frequentist network and pairwise, random-effects meta-analysis.

RESULTS

Twenty-two trials (99,591 participants, 25.2% female) were included. Female sex was significantly associated with a higher 1-year MACCE risk (hazard ratio 1.14 [95% confidence interval 1.02-1.28]) and bleeding (1.13 [1.00-1.28]), but not NACCE (1.12 [0.96-1.31]). In sub-analyses, the association between female sex and MACCE was related to use of clopidogrel as the second antiplatelet agent (1.11 [1.03-1.20]), whereas higher bleeding events were related to newer P2Y12 inhibitors (P2Y12i) (1.58 [1.01-2.46]). For DAPT duration, short-term DAPT followed by P2Y12i monotherapy was non-inferior for MACCE in females and males (0.95 [95% CI 0.83-1.10; and 0.96 [0.80-1.16]) but tended to be superior in males for NACCE versus 12-month DAPT (0.96 [0.91-1.01]); mid-term DAPT tended to be associated with a lower bleeding risk in males (0.43 [0.17-1.09]).

CONCLUSIONS

Female sex is associated with higher MACCE and bleeding when newer P2Y12i agents are used. Short-term DAPT followed by P2Y12i monotherapy is safe and effective in both sexes undergoing PCI.

CLINICAL TRIALS REGISTRATION

PROSPERO ID: CRD42021278663.

Risk Factors of Chemotherapy-Induced Thrombocytopenia After Oxaliplatin-Containing Chemotherapy for Gastrointestinal Malignancies

PURPOSE

Thrombocytopenia is among the most common chemotherapy-related hematologic toxicities. We aim to determine the predictors of oxaliplatin chemotherapy-induced thrombocytopenia in patients with gastrointestinal tumors to guide the clinic.

METHODS

Clinical data of 750 patients with a malignant gastrointestinal tumor were included as the primary cohort. Basic clinical data, serological indices, and anthropometric indices of these patients were collected. According to the presence or absence of CIT, univariate analysis was performed to identify significant factors for multivariate analysis. In R language software, nomogram was constructed based on the results of multi-factor analysis, and the calibration curve and ROC curve were drawn.

RESULTS

Univariate analysis identified 17 factors as closely related to CIT occurrence, namely age, lymph node metastasis (N) stage, metastasis (M) stage, lung metastasis, other site metastasis, chemotherapy regimen, course of treatment, total dose of oxaliplatin, AST, albumin, neutrophils, monocytes, baseline platelets, transferrin, natural killer (NK) cell, phase angle, and SMI (P < 0.10). The binary logistic multivariate regression analysis revealed five independent risk factors for developing CIT (P < 0.05), including the M stage, total dose of oxaliplatin, albumin, baseline thrombocyte count, and NK cell. Based on the results of multivariate logistic regression analysis, R software was used to establish a nomogram model. The calibration curve shows that the combined predictor has good consistency. The area under the ROC curve was 0.877 and the best cut-off value was 0.3579613 (sensitivity, 78.9%; specificity, 81.8%), which showed the better prediction efficiency.

CONCLUSION

The total dose of oxaliplatin, M stage, albumin, baseline platelet count, and NK cell was independent risk factors for CIT. The sequentially constructed histogram model had a good predictive effect on the risk of thrombocytopenia caused by oxaliplatin chemotherapy in patients with gastrointestinal malignancies.

Prevalence and risk factors for proximal deep vein thrombosis at admission in patients with traumatic fractures: a multicenter retrospective study

Objective

This study aimed to determine the associated risk factors for proximal deep vein thrombosis (DVT) in patients with lower extremity and pelvic-acetabular fractures.

Methods

The medical records of 4,056 patients with lower extremity and pelvic-acetabular fractures were retrospectively reviewed. The patients were classified into proximal or non-proximal DVT groups. Logistic regression models were used to determine the independent risk variables for proximal DVT. The predictive value of the related risk factors was further analyzed using receiver operating characteristic curves.

Results

The prevalence of proximal DVT was 3.16%. Sex, body mass index (BMI), fracture site, injury mechanism, diabetes, coronary heart disease (CHD), injury-to-admission interval, hematocrit, platelet counts, and D-dimer levels differed significantly between the two groups. BMI ≥ 24.0 kg/m2, femoral shaft fractures, high-energy injury, diabetes, injury-to-admission interval >24 h were independent risk factors for proximal DVT. CHD decreased the risk of proximal DVT. The platelet and D-dimer had high negative predictive value for predicting proximal DVT formation, with cut-off values of 174 × 109/L and 2.18 mg/L, respectively.

Conclusion

BMI ≥ 24.0 kg/m2, femoral shaft fractures, high-energy injury, diabetes, injury-to-admission interval >24 h were independent risk factors for proximal DVT in patients with lower extremity and pelvic-acetabular fractures. Platelet count and D-dimer level were effective indicators for excluding proximal DVT occurrence. CHD decreased the risk of proximal DVT.

Sex Differences in Bleeding Risk Associated With Antithrombotic Therapy Following Percutaneous Coronary Intervention

Background: Antithrombotic therapy is crucial for secondary prevention of cardiovascular disease (CVD), but women with CVD may face increased bleeding complications post-percutaneous coronary intervention (PCI) under antithrombotic therapy. However, women are often underrepresented in clinical trials in this field, so evidence for sex-specific recommendations is lacking. Methods and Results: A search on PubMed was conducted for English-language articles addressing bleeding complications and antithrombotic therapy in women. Despite women potentially showing higher baseline platelet responsiveness than men, the clinical implications remain unclear. Concerning antiplatelet therapy post-PCI, although women have an elevated bleeding risk in the acute phase, no sex differences were observed in the chronic phase. However, women require specific considerations for factors such as age, renal function, and weight when determining the dose and duration of antiplatelet therapy. Regarding anticoagulation post-PCI, direct oral anticoagulants may pose a lower bleeding risk in women compared with warfarin. Concerning triple antithrombotic therapy (TAT) post-PCI for patients with atrial fibrillation, there is a lack of evidence on whether sex differences should be considered in the duration and regimen of TAT. Conclusions: Recent findings on sex differences in post-PCI bleeding complications did not provide enough evidence to recommend specific therapies for women. Further studies are needed to address this gap and recommend optimal antithrombotic therapy post-PCI for women.

Platelet Reactivity in the Exacerbation of Psoriasis

Background: Psoriasis is a chronic, inflammatory, immune-mediated disease with a specific cutaneous presentation. Increased platelet aggregation has been observed in patients with extensive psoriatic lesions. The aim of this study was to evaluate the clinical factors affecting platelet reactivity in patients with an exacerbation of psoriasis. Methods: This was a prospective, single-center, observational study, enrolling patients hospitalized for an aggravation of psoriasis. Enrolled patients underwent single platelet function testing with light transmission aggregometry on the first morning of hospitalization. Results: 120 patients were enrolled in the study. Of the compared subgroups, women had higher maximal platelet aggregation (MPA) than men (77% vs. 72%; p = 0.03), and those with BMIs < 25 kg/m2 showed higher platelet reactivity compared to subjects with BMIs ≥ 25 kg/m2 (75% vs. 73%; p = 0.02). There was a positive correlation between MPA and platelet count (r = 0.27; p < 0.01), as well as C-reactive protein concentration (r = 0.20; p = 0.03), while a negative correlation was observed with total cholesterol (r = -0.24; p = 0.01) and triglycerides (r = -0.30; p < 0.01). A two-step analysis based on multidimensional models with random effects revealed that every increase in the platelet count by 103/μL led to an increase in MPA by 0.07% (R2 = 0.07; p < 0.01), and an increase in triglycerides' concentration by 1 mg/dL was related to a reduction in MPA by 0.05% (R2 = 0.07; p < 0.01). Conclusions: The increased platelet reactivity observed in patients with psoriasis appears to be multifactorial and related to several clinical and laboratory features. Further research is warranted to put these findings into a clinical perspective.

Platelet P2Y12 signalling pathway in the dysregulated immune response during sepsis

Sepsis is a complicated pathological condition in response to severe infection. It is characterized by a strong systemic inflammatory response, where multiple components of the immune system are involved. Currently, there is no treatment for sepsis. Blood platelets are known for their role in haemostasis, but they also participate in inflammation through cell-cell interaction and the secretion of inflammatory mediators. Interestingly, an increase in platelet activation, secretion, and aggregation with other immune cells (such as monocytes, T-lymphocytes and neutrophils) has been detected in septic patients. Therefore, antiplatelet therapy in terms of P2Y12 antagonists has been evaluated as a possible treatment for sepis. It was found that blocking P2Y12 receptors decreased platelet marker expression and limited attachment to immune cells in some studies, but not in others. This review addresses the role of platelets in sepsis and discusses whether antagonizing P2Y12 signalling pathways can alter the disease outcome. Challenges in studying P2Y12 antagonists in sepsis also are discussed. LINKED ARTICLES: This article is part of a themed issue on Platelet purinergic receptor and non-thrombotic disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.4/issuetoc.

Stimulation of platelet P2Y1 receptors by different endogenous nucleotides leads to functional selectivity via biased signalling

BACKGROUND AND PURPOSE

Platelet function during inflammation is dependent on activation by endogenous nucleotides. Non-canonical signalling via the P2Y1 receptor is important for these non-thrombotic functions of platelets. However, apart from ADP, the role of other endogenous nucleotides acting as agonists at P2Y1 receptors is unknown. This study compared the effects of ADP, Ap3A, NAD+ , ADP-ribose, and Up4A on platelet functions contributing to inflammation or haemostasis.

EXPERIMENTAL APPROACH

Platelets obtained from healthy human volunteers were incubated with ADP, Ap3A, NAD+ , ADP-ribose, or Up4A, with aggregation and fibrinogen binding measured (examples of function during haemostasis) or before exposure to fMLP to measure platelet chemotaxis (an inflammatory function). In silico molecular docking of these nucleotides to the binding pocket of P2Y1 receptors was then assessed.

KEY RESULTS

Platelet aggregation and binding to fibrinogen induced by ADP was not mimicked by NAD+ , ADP-ribose, and Up4A. However, these endogenous nucleotides induced P2Y1 -dependent platelet chemotaxis, an effect that required RhoA and Rac-1 activity, but not canonical PLC activity. Analysis of molecular docking of the P2Y1 receptor revealed distinct differences of amino acid interactions and depth of fit within the binding pocket for Ap3A, NAD+ , ADP-ribose, or Up4A compared with ADP.

CONCLUSION AND IMPLICATIONS

Platelet function (aggregation vs motility) can be differentially modulated by biased-agonist activation of P2Y1 receptors. This may be due to the character of the ligand-binding pocket interaction. This has implications for future therapeutic strategies aimed to suppress platelet activation during inflammation without affecting haemostasis as is the requirement of current ant-platelet drugs.

LINKED ARTICLES

This article is part of a themed issue on Platelet purinergic receptor and non-thrombotic disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.4/issuetoc.

Sex, Endothelial Cell Functions, and Peripheral Artery Disease

Peripheral artery disease (PAD) is caused by blocked arteries due to atherosclerosis and/or thrombosis which reduce blood flow to the lower limbs. It results in major morbidity, including ischemic limb, claudication, and amputation, with patients also suffering a heightened risk of heart attack, stroke, and death. Recent studies suggest women have a higher prevalence of PAD than men, and with worse outcomes after intervention. In addition to a potential unconscious bias faced by women with PAD in the health system, with underdiagnosis, and lower rates of guideline-based therapy, fundamental biological differences between men and women may be important. In this review, we highlight sexual dimorphisms in endothelial cell functions and how they may impact PAD pathophysiology in women. Understanding sex-specific mechanisms in PAD is essential for the development of new therapies and personalized care for patients with PAD.

Sex Differences in Therapies against Myocardial Ischemia-Reperfusion Injury: From Basic Science to Clinical Perspectives

Mortality from myocardial infarction (MI) has declined over recent decades, which could be attributed in large part to improved treatment methods. Early reperfusion is the cornerstone of current MI treatment. However, reoxygenation via restored blood flow induces further damage to the myocardium, leading to ischemia-reperfusion injury (IRI). While experimental studies overwhelmingly demonstrate that females experience greater functional recovery from MI and decreased severity in the underlying pathophysiological mechanisms, the outcomes of MI with subsequent reperfusion therapy, which is the clinical correlate of myocardial IRI, are generally poorer for women compared with men. Distressingly, women are also reported to benefit less from current guideline-based therapies compared with men. These seemingly contradicting outcomes between experimental and clinical studies show a need for further investigation of sex-based differences in disease pathophysiology, treatment response, and a sex-specific approach in the development of novel therapeutic methods against myocardial IRI. In this literature review, we summarize the current knowledge on sex differences in the underlying pathophysiological mechanisms of myocardial IRI, including the roles of sex hormones and sex chromosomes. Furthermore, we address sex differences in pharmacokinetics, pharmacodynamics, and pharmacogenetics of current drugs prescribed to limit myocardial IRI. Lastly, we highlight ongoing clinical trials assessing novel pharmacological treatments against myocardial IRI and sex differences that may underlie the efficacy of these new therapeutic approaches.

The Signaling Pathway of the ADP Receptor P2Y12 in the Immune System: Recent Discoveries and New Challenges

P2Y12 is a G-protein-coupled receptor that is activated upon ADP binding. Considering its well-established role in platelet activation, blocking P2Y12 has been used as a therapeutic strategy for antiplatelet aggregation in cardiovascular disease patients. However, receptor studies have shown that P2Y12 is functionally expressed not only in platelets and the microglia but also in other cells of the immune system, such as in monocytes, dendritic cells, and T lymphocytes. As a result, studies were carried out investigating whether therapies targeting P2Y12 could also ameliorate inflammatory conditions, such as sepsis, rheumatoid arthritis, neuroinflammation, cancer, COVID-19, atherosclerosis, and diabetes-associated inflammation in animal models and human subjects. This review reports what is known about the expression of P2Y12 in the cells of the immune system and the effect of P2Y12 activation and/or inhibition in inflammatory conditions. Lastly, we will discuss the major problems and challenges in studying this receptor and provide insights on how they can be overcome.

Sex-stratified differences in early antithrombotic treatment response in patients presenting with ST-segment elevation myocardial infarction

BACKGROUND

The mechanisms underlying the increased risk of bleeding that female patients with ST-segment Elevation Myocardial Infarction (STEMI) exhibit, remains unclear. The present report assessed sex-related differences in response to pre-hospital dual antiplatelet therapy (DAPT) initiation in patients with STEMI.

METHODS

The COMPARE CRUSH trial randomized patients presenting with STEMI to receive a pre-hospital loading dose of crushed or integral prasugrel tablets in the ambulance. In this substudy, we compared platelet reactivity levels and the occurrence of high platelet reactivity (HPR; defined as platelet reactivity ≥208) between sexes at 4 prespecified time points after DAPT initiation, and evaluated post-PCI bleeding between groups.

RESULTS

Out of 633 STEMI patients, 147 (23%) were female. Females compared with males presented with significantly higher levels of platelet reactivity and higher HPR rates at baseline (232 [IQR, 209-256] vs 195 [IQR, 171-220], P < .01, and 76% vs 41%, OR 4.58 [95%CI, 2.52-8.32], P < .01, respectively). Moreover, female sex was identified as the sole independent predictor of HPR at baseline (OR 5.67 [95%CI, 2.56-12.53], P < .01). Following DAPT initiation, levels of platelet reactivity and the incidence of HPR were similar between sexes. Post-PCI bleeding occurred more frequently in females compared with males (10% vs 2%, OR 6.02 [95%CI, 2.61-11.87], P < .01). Female sex was an independent predictor of post-PCI bleeding (OR 3.25 [95%CI, 1.09-9.72], P = .04).

CONCLUSIONS

In this contemporary STEMI cohort, female STEMI patients remain at risk of bleeding complications after primary PCI. However, this is not explained by sex-specific differences in the pharmacodynamic response to pre-hospital DAPT initiation.

Sex-related differences in the response of anti-platelet drug therapies targeting purinergic signaling pathways in sepsis

Sepsis, a complex clinical syndrome resulting from a serious infection, is a major healthcare problem associated with high mortality. Sex-related differences in the immune response to sepsis have been proposed but the mechanism is still unknown. Purinergic signaling is a sex-specific regulatory mechanism in immune cell physiology. Our studies have shown that blocking the ADP-receptor P2Y12 but not P2Y1 receptor was protective in male mice during sepsis, but not female. We now hypothesize that there are sex-related differences in modulating P2Y12 or P2Y1 signaling pathways during sepsis. Male and female wild-type (WT), P2Y12 knock-out (KO), and P2Y1 KO mice underwent sham surgery or cecal ligation and puncture (CLP) to induce sepsis. The P2Y12 antagonist ticagrelor or the P2Y1 antagonist MRS2279 were administered intra-peritoneally after surgery to septic male and female mice. Blood, lungs and kidneys were collected 24 hours post-surgery. Sepsis-induced changes in platelet activation, secretion and platelet interaction with immune cells were measured by flow cytometry. Neutrophil infiltration in the lung and kidney was determined by a myeloperoxidase (MPO) colorimetric assay kit. Sepsis-induced platelet activation, secretion and aggregate formation were reduced in male CLP P2Y12 KO and in female CLP P2Y1 KO mice compared with their CLP WT counterpart. Sepsis-induced MPO activity was reduced in male CLP P2Y12 KO and CLP P2Y1 KO female mice. CLP males treated with ticagrelor or MRS2279 showed a decrease in sepsis-induced MPO levels in lung and kidneys, aggregate formation, and platelet activation as compared to untreated male CLP mice. There were no differences in platelet activation, aggregate formation, and neutrophil infiltration in lung and kidney between female CLP mice and female CLP mice treated with ticagrelor or MRS2279. In human T lymphocytes, blocking P2Y1 or P2Y12 alters cell growth and secretion in vitro in a sex-dependent manner, supporting the data obtained in mice. In conclusion, targeting purinergic signaling represents a promising therapy for sepsis but drug targeting purinergic signaling is sex-specific and needs to be investigated to determine sex-related targeted therapies in sepsis.

The NO/cGMP/PKG pathway in platelets: The therapeutic potential of PDE5 inhibitors in platelet disorders

Platelets are the "guardians" of the blood circulatory system. At sites of vessel injury, they ensure hemostasis and promote immunity and vessel repair. However, their uncontrolled activation is one of the main drivers of thrombosis. To keep circulating platelets in a quiescent state, the endothelium releases platelet antagonists including nitric oxide (NO) that acts by stimulating the intracellular receptor guanylyl cyclase (GC). The latter produces the second messenger cyclic guanosine-3',5'-monophosphate (cGMP) that inhibits platelet activation by stimulating protein kinase G, which phosphorylates hundreds of intracellular targets. Intracellular cGMP pools are tightly regulated by a fine balance between GC and phosphodiesterases (PDEs) that are responsible for the hydrolysis of cyclic nucleotides. Phosphodiesterase type 5 (PDE5) is a cGMP-specific PDE, broadly expressed in most tissues in humans and rodents. In clinical practice, PDE5 inhibitors (PDE5i) are used as first-line therapy for erectile dysfunction, pulmonary artery hypertension, and lower urinary tract symptoms. However, several studies have shown that PDE5i may ameliorate the outcome of various other conditions, like heart failure and stroke. Interestingly, NO donors and cGMP analogs increase the capacity of anti-platelet drugs targeting the purinergic receptor type Y, subtype 12 (P2Y12) receptor to block platelet aggregation, and preclinical studies have shown that PDE5i inhibits platelet functions. This review summarizes the molecular mechanisms underlying the effect of PDE5i on platelet activation and aggregation focusing on the therapeutic potential of PDE5i in platelet disorders, and the outcomes of a combined therapy with PDE5i and NO donors to inhibit platelet activation.

Gender-differences in antithrombotic therapy across the spectrum of ischemic heart disease: Time to tackle the Yentl syndrome?

The incidence and clinical presentation of ischemic heart disease (IHD), as well as thrombotic and bleeding risks, appear to differ between genders. Compared with men, women feature an increased thrombotic risk, probably related to an increased platelet reactivity, higher level of coagulation factors, and sex-associated unique cardiovascular risk factors, such as pregnancy-related (i.e., pre-eclampsia and gestational diabetes), gynecological disorders (i.e., polycystic ovary syndrome, early menopause) and autoimmune or systemic inflammatory diseases. At the same time, women are also at increased risk of bleeding, due to inappropriate dosing of antithrombotic agents, smaller blood vessels, lower body weight and comorbidities, such as diabetes and chronic kidney disease. Pharmacological strategies focused on the personalization of antithrombotic treatment may, therefore, be particularly appealing in women in light of their higher bleeding and ischemic risks. Paradoxically, although women represent a large proportion of cardiovascular patients in our practice, adequate high-quality clinical trial data on women remain scarce and inadequate to guide decision-making processes. As a result, IHD in women tends to be understudied, underdiagnosed and undertreated, a phenomenon known as a "Yentl syndrome." It is, therefore, compelling for the scientific community to embark on dedicated clinical trials to address underrepresentation of women and to acquire evidence-based knowledge in the personalization of antithrombotic therapy in women.

Identifying Sex Dimorphism in Peripheral Artery Disease with Platelet Mapping

INTRODUCTION

Clinical outcomes in women with PAD after revascularization procedures are worse as compared to men, yet there is little in the existing literature as why this may be the case. Platelet Mapping is an emerging point-of-care viscoelastic technology that measures the comprehensive properties of a blood clot, including fibrin-platelet interactions. This prospective observational study aimed to characterize the clinical and Platelet Mapping profiles of female and male patients undergoing lower extremity revascularization, and to correlate Platelet Mapping distribution to thrombotic potential.

METHODS

All patients with a diagnosis of PAD undergoing named vessel open or endovascular revascularization to reestablish either inflow, outflow, or both, during December 2020 and January 2022 were prospectively included. Patients were followed clinically for thrombosis for up to one year. Platelet Mapping assays were performed in three clinical phases: preoperative, postoperative inpatient and postoperative outpatient. Inferential analysis between female and male patient was performed. The quartile distribution of Platelet Mapping metrics associated with thrombosis was used to infer to thrombotic potential.

RESULTS

One hundred and seven patients were enrolled, of which thirty-seven (34.6%) were female. Female patients had significantly lower rates of uncontrolled diabetes [2.7% vs. 18.6%], hypertension requiring combination therapy [37.8% vs. 58.6%], CKD [27.0% vs. 51.4%], CAD [29.7% vs. 57.1%] and MI [16.2% vs. 35.7%], (all p<0.05). Platelet reactivity was significantly higher in female patients with greater platelet aggregation [75.9±23.3 vs. 63.5±28.8] and lower platelet inhibition [23.8±23.4 vs. 36.8±28.9] (all p<0.01). This trend was consistent over time when stratified by the postoperative inpatient and postoperative outpatient clinical phases. There was no statistically discernable difference in the use of antiplatelet therapy between groups, yet female patients continued to exhibit greater platelet reactivity when analyzed by type of pharmacologic regimen [platelet aggregation on monoantiplatelet therapy: 80.6±21.0 in women vs. 69.4±25.0 in men; platelet aggregation on dual antiplatelet therapy: 67.9±23.8 in women vs. 44.8±31.8 in men] (all p<0.01). 21 patients experienced postoperative graft/stent thrombosis within the study period. In relation to the overall study population, patients with thrombosis had Platelet Mapping metrics above the 50^th percentile of overall platelet aggregation distribution.

CONCLUSION

There is a growing appreciation for the differences in etiology, disease progression and outcomes of cardiovascular conditions as they relate to sex. In this cohort, traditional cardiovascular risk factors were in lower prevalence in female patients. Platelet reactivity was found to be higher across clinical phases and antiplatelet regimens. High platelet reactivity was also associated with an increased incidence of thrombosis after lower extremity revascuarlization. These hypothesis-generating findings provide the basis for further exploration of sex-specific coagulation profiling in PAD patients.

Sex differences at the platelet-vascular interface

Platelets are multifunctional cells that ensure the integrity of the vascular wall and modulate the immune response at the blood/vascular interface. Their pathological activation results in both thrombosis and inflammation and implicates them in the pathogenesis of vascular disease. Vascular diseases are sexually dimorphic in terms of incidence, clinical presentation, outcome, and efficacy of anti-platelet therapy. We here provide an overview of what is known about the role of platelets in the initiation and progression of vascular diseases and summarize what is known about the sex differences in platelet reactivity and in the thromboinflammatory mechanisms that drive these diseases, with a particular focus on atherosclerosis, obstructive and non-obstructive coronary artery disease, and ischemic stroke. Understanding the sex differences at the platelet-vascular interface is clinically relevant as it will enable: (1) to design new therapeutic strategies that prevent the detrimental effects of the immune-modulatory function of platelets taking sex into account, and (2) to evaluate if sex-specific anti-platelet drug regimens should be used to reduce the risk not only of thrombosis but also of vascular disease progression.

Platelet Activation Favours NOX2-Mediated Muscle Damage in Elite Athletes: The Role of Cocoa-Derived Polyphenols

Mechanisms of exercise-induced muscle injury with etiopathogenesis and its consequences have been described; however, the impact of different intensities of exercise on the mechanisms of muscular injury development is not well understood. The aim of this study was to exploit the relationship between platelet activation, oxidative stress and muscular injuries induced by physical exercise in elite football players compared to amateur athletes. Oxidant/antioxidant status, platelet activation and markers of muscle damage were evaluated in 23 elite football players and 23 amateur athletes. Compared to amateurs, elite football players showed lower antioxidant capacity and higher oxidative stress paralleled by increased platelet activation and muscle damage markers. Simple linear regression analysis showed that sNOX2-dp and H₂O₂, sCD40L and PDGF-bb were associated with a significant increase in muscle damage biomarkers. In vitro studies also showed that plasma obtained from elite athletes increased oxidative stress and muscle damage in human skeletal muscle myoblasts cell line compared to amateurs’ plasma, an effect blunted by the NOX2 inhibitor or by the cell treatment with cocoa-derived polyphenols. These results indicate that platelet activation increased muscular injuries induced by oxidative stress. Moreover, NOX2 inhibition and polyphenol extracts treatment positively modulates redox status and reduce exercise-induced muscular injury.

Hypothermia Induced Impairment of Platelets: Assessment With Multiplate vs. ROTEM—An In Vitro Study

Introduction: This experimental in vitro study aimed to identify and characterize hypothermia-associated coagulopathy and to compare changes in mild to severe hypothermia with the quantitative measurement of rotational thromboelastometry (ROTEM) and multiple-electrode aggregometry (MULTIPLATE).

Methods: Whole blood samples from 18 healthy volunteers were analyzed at the target temperatures of 37, 32, 24, 18, and 13.7°C with ROTEM (ExTEM, InTEM and FibTEM) and MULTIPLATE using the arachidonic acid 0.5 mM (ASPI), thrombin receptor-activating peptide-6 32 µM (TRAP) and adenosine diphosphate 6.4 µM (ADP) tests at the corresponding incubating temperatures for coagulation assessment.

Results: Compared to baseline (37°C) values ROTEM measurements of clotting time (CT) was prolonged by 98% (at 18°C), clot formation time (CFT) was prolonged by 205% and the alpha angle dropped to 76% at 13.7°C (p < 0.001). At 24.0°C CT was prolonged by 56% and CFT by 53%. Maximum clot firmness was only slightly reduced by ≤2% at 13.7°C. Platelet function measured by MULTIPLATE was reduced with decreasing temperature (p < 0.001): AUC at 13.7°C −96% (ADP), −92% (ASPI) and −91% (TRAP).

Conclusion: Hypothermia impairs coagulation by prolonging coagulation clotting time and by decreasing the velocity of clot formation in ROTEM measurements. MULTIPLATE testing confirms a linear decrease in platelet function with decreasing temperatures, but ROTEM fails to adequately detect hypothermia induced impairment of platelets.

Improving the Quality of EDTA-treated Blood Specimens from Mice

Nonterminal blood sampling in laboratory mice is a very common procedure. With the goal of improving animal welfare, different sampling sites and methods have been compared but have not achieved a consensus. Moreover, most of these studies overlooked the quality of blood specimens collected. The main preanalytical concern with EDTA-treated blood specimens for hematology analyses is platelet aggregation, which is known to cause analytical errors. Our objective was to find a nonterminal blood sampling method with minimal adverse effects on mice and few or no platelet aggregates. We tested and compared 2 collection sites, 4 sampling methods, and 3 antithrombotic drugs in 80 C57BL6/j male and female mice by evaluating platelet aggregates on blood smears and platelet, WBC, and RBC counts. In addition, the blood collection process was carefully evaluated, and adverse effects were recorded. Platelet aggregation was lower in specimens collected from the jugular vein than from the facial vein, with no effect of the sampling device or the presence of an antithrombotic additive. Highly aggregated specimens were significantly associated with lower platelet counts, whereas aggregation had no effect on WBC or RBC counts. Adverse events during sampling were significantly associated with more numerous platelet aggregates. The jugular vein is thus a satisfactory sampling site in mice in terms of both animal welfare and low platelet aggregation. Using antithrombotic agents appears to be unnecessary, whereas improving sampling conditions remains a key requirement to ensure the quality of EDTA-treated blood specimens from mice.

Colorectal cancer chemotherapy: can sex-specific disparities impact on drug toxicities?

Purpose

Given the biological differences between females and males, sex-specific evaluations should be carried out to obtain better cancer prevention, diagnosis, and treatment strategies. To this purpose, our aim was to evaluate sex differences for toxicity in a cohort of colorectal cancer (CRC) patients undergoing chemotherapy.

Methods

We performed a retrospective study in 329 CRC patients. Differences between males and females were tested performing the Mann-Whitney U test or the Fisher exact test. Multivariate logistic regression models were computed to evaluate the association between sex and risk of chemotherapy agent-related toxicity.

Results

According association sex toxicity, significant differences were observed in the median number of episodes of nausea (p = 0.044), vomit (p = 0.007), heartburn (p = 0.022), thrombocytopenia (p = 0.005), mucositis (p = 0.024). Moreover, statistically significant differences between males and females were observed in the distribution of the highest toxicity grades of nausea (p = 0.024), heartburn (p = 0.016), and thrombocytopenia (p = 0.034). Females have an increased risk of vomit (p = 0.002), alopecia (p = 0.035), heartburn (p = 0.005), mucositis (p = 0.003), and lower risk for thrombocytopenia (p = 0.005).

Conclusion

According to the association of sex chemotherapy agent-related toxicities, females resulted on average at a significant increased risk of more common adverse events (constipation, dysgeusia, alopecia, heartburn, vomit, asthenia, nausea, pain events, and mucositis). Sex-tailored CRC chemotherapy treatment is necessary to obtain efficacy avoiding toxicity, based on patients’ biological and genetic characteristics, a vision that would change CRC setting, a stable disease but still orphan of a real tailored approach.

Supplementary information

The online version contains supplementary material available at 10.1007/s00228-022-03298-y.

Gender-specific differences in haemostatic parameters and their influence on blood loss in bimaxillary surgery

Objective

The objectives of this prospective cohort study were to establish gender-related differences in blood loss and haemostatic profiles associated with bimaxillary surgery. In addition, we aimed to identify if any gender differences could be established which might help predict blood loss volume.

Materials and methods

Fifty-four patients (22 males; 32 females) undergoing bimaxillary surgery for skeletal dentofacial deformities were eligible for inclusion. Blood samples were taken 1 day preoperatively and 48 h postoperatively for detailed gender-specific coagulation analysis incorporating global coagulation assays (endogenous thrombin potential) and specific coagulation parameters. Blood loss was measured at two different time points: (1) the end of surgery, visible intraoperative blood loss (IOB) using ‘subtraction method’; and (2) 48 h postoperatively perioperative bleeding volume (CBL-48 h) using ‘haemoglobin-balance method’ and Nadler’s formula. Correlation and regression analyses were performed to identify relevant parameters affecting the amount of blood loss.

Results

Significant differences in IOB and CBL-48 h were observed (p < 0.001). Men had higher IOB versus women, lacking statistical significance (p = 0.056). In contrast, men had significantly higher CLB-48 h (p = 0.019). Reduced CBL-48 h was shown to be most closely associated with the level of Antithrombin-III being decreased in females.

Conclusions

Male gender is associated with higher IOB and CBL-48 compared with females. Gender does not affect IOB regarding haemostatic profile but does correlate strongly with procedure length. Conversely, CBL-48 is closely associated with gender-specific imbalances in the anticoagulant system.

Clinical relevance

Knowledge of gender-related differences will help clinicians establish predictive factors regarding excessive blood loss in orthognathic surgery and identify at-risk patients.

Evaluation of the equivalence of different intakes of Fruitflow in affecting platelet aggregation and thrombin generation capacity in a randomized, double-blinded pilot study in male subjects

BACKGROUND

The water-soluble tomato extract, Fruitflow® is a dietary antiplatelet which can be used to lower platelet aggregability in primary preventative settings. We carried out a pilot study to investigate the range of intakes linked to efficacy and to make an initial assessment of variability in response to Fruitflow®.

METHODS

Platelet response to adenosine diphosphate (ADP) agonist and thrombin generation capacity were monitored at baseline and 24 h after consuming 0, 30, 75, 150 or 300 mg of Fruitflow® in a randomized, double-blinded crossover study in male subjects 30-65 years of age (N = 12). Results were evaluated for equivalence to the standard 150 mg dose.

RESULTS

Results showed that the changes from baseline aggregation and thrombin generation observed after the 75 mg, 150 mg, and 300 mg supplements were equivalent. Aggregation was reduced from baseline by - 12.9 ± 17.7%, - 12.0 ± 13.9% and - 17.7 ± 15.7% respectively, while thrombin generation capacity fell by - 8.6 ± 4.1%, - 9.2 ± 3.1% and - 11.3 ± 2.3% respectively. Effects observed for 0 mg and 30 mg supplements were non-equivalent to 150 mg and not different from baseline (aggregation changed by 3.0 ± 5.0% and - 0.7 ± 10.2% respectively, while thrombin generation changed by 0.8 ± 3.0% and 0.8 ± 3.1% respectively).

CONCLUSIONS

The data suggest that the efficacious range for Fruitflow® lies between 75 mg and 300 mg, depending on the individual. It may be pertinent to personalize the daily intake of Fruitflow® depending on individual platelet response.

TRIAL REGISTRATION

ISRCTN53447583 , 24/02/2021.

A Comparative Study of Multiple Electrode Aggregometry Technologies in Cardiac Surgery: Different Values, Same Clinical Relevance

OBJECTIVES

The assessment of platelet function in cardiac surgery patients who recently received dual-antiplatelet therapy is considered in the existing guidelines. Among available devices, Multiplate (MP) and ROTEM Platelet (RP) are both based on electrical impedance. This study aimed to determine the agreement between MP and RP in cardiac surgery patients under dual-antiplatelet therapy discontinued before surgery. Secondarily, it compared the ability of the MP and RP in predicting postoperative bleeding and the need for platelet transfusion.

DESIGN

A prospective cohort study.

SETTING

A hospital in Milan, Italy.

PARTICIPANTS

Fifty adult patients preoperatively and postoperatively tested.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients were studied with adenosine diphosphate (ADP) and thrombin receptor-activating peptide (TRAP) testing on both of the devices. The mean preoperative ADP tests were below the respective lower limit of the reference value, thus reflecting a good ability of these tests to detect the residual or ongoing effects of antiplatelet drugs acting on the P2Y₁₂ receptor. The agreement between the 2 methodologies was very poor for both the ADP and TRAP tests, with a percentage error of 80%. The preoperative ADP tests were predictive for the need of platelet concentrate transfusion, with cut-off values at 35 U for the ADP-MP and 60 Ω/min for the ADP-RP. No correlation was found for postoperative bleeding.

CONCLUSION

Both technologies seemed to offer potential benefits in the surgical approach to patients who preoperatively received antiplatelet drugs. However, the results of these tests are not interchangeable, and different cut-off values should be applied.

Effects of Nutrients on Platelet Function: A Modifiable Link between Metabolic Syndrome and Neurodegeneration?

Metabolic syndrome increases the risk of vascular dementia and other neurodegenerative disorders. Recent studies underline that platelets play an important role in linking peripheral with central metabolic and inflammatory mechanisms. In this narrative review, we address the activation of platelets in metabolic syndrome, their effects on neuronal processes and the role of the mediators (e.g., serotonin, platelet-derived growth factor). Emerging evidence shows that nutritional compounds and their metabolites modulate these interactions-specifically, long chain fatty acids, endocannabinoids and phenolic compounds. We reviewed the role of activated platelets in neurovascular processes and nutritional compounds in platelet activation.

Platelet Aggregation Assays Do Not Reliably Diagnose Platelet Delta Granule Storage Pool Deficiency

Background

Patients with platelet dysfunction disorders present with a variety of mucocutaneous bleeding symptoms including easy bruising, frequent epistaxis, bleeding gums upon tooth brushing and for women, heavy menstrual bleeding. Available laboratory assays to evaluate platelet function include the platelet function analyzer (PFA) and in larger centers with coagulation laboratories, light transmission platelet aggregometry (LTA) analyses. Both assays are known to have a number of limitations, especially in the diagnosis of platelet delta granule storage pool deficiency (δ-SPD). δ-SPD is an underdiagnosed condition caused by decreased numbers of platelet dense granules (DGs) and is best diagnosed by electron microscopy (EM). Patients with platelet δ-SPD have a decreased response to low levels of the agonist adenosine diphosphate (ADP) in the second wave of light transmittance with LTA or decreased ADP secretion by fluorescence lumiaggregometry. There are few reports that have evaluated patients with δ-SPD and their respective LTA results. One report published in 1987 described normal LTA assays in 23% of patients with δ-SPD; a more recent report described LTA as having the sensitivity to detect only about 52% of patients with δ-SPD. The purpose of our study was intended to review the LTA and EM results of patients suspected of having a platelet function disorder at our institution for comparison with previously published studies.

Methods

Our study included 344 patients who had been evaluated by both LTA and whole mount EM. Aggregometry utilized five agonists: ADP, epinephrine, collagen, arachidonic acid, and ristocetin. DGs were enumerated in 100 whole-mounted platelets to determine a mean number of dense granules per platelet (DGs/PL).

Results

Seventy-seven percent of our patients were found to have δ-SPD (264/344); 68% (179/264) of these subjects had an abnormal platelet LTA. Thirty-two percent (85/264) of our patients had normal LTA results but were found to have δ-SPD with a mean of 2.54 ± 0.15 DG/PL (normal = 4 - 6 DG/PL).

Conclusion

These data confirm previous reports suggesting the utilization of LTA alone in patients with histories of unexplained bleeding may miss the diagnosis of platelet δ-SPD. It is, therefore, prudent to assess platelet DG number by EM, especially if platelet LTA assessment is normal.

Sex Differences of the Diabetic Heart

Type 2 diabetes is a chronic disease associated with micro- and macro-vascular complications, including myocardial ischemia, and also with a specific and intrinsic cardiac dysfunction called diabetic cardiomyopathy (DCM). Both clinical and animal studies demonstrate significant sex differences in prevalence, pathophysiology, and outcomes of cardiovascular diseases (CVDs), including those associated with diabetes. The increased risk of CVDs with diabetes is higher in women compared to men with 50% higher risk of coronary artery diseases and increased mortality when exposed to acute myocardial infarction. Clinical studies also reveal a sexual dimorphism in the incidence and outcomes of DCM. Based on these clinical findings, growing experimental research was initiated to understand the impact of sex on CVDs associated with diabetes and to identify the molecular mechanisms involved. Endothelial dysfunction, atherosclerosis, coagulation, and fibrosis are mechanisms found to be sex-differentially modulated in the diabetic cardiovascular system. Recently, impairment of energy metabolism also emerged as a determinant of multiple CVDs associated with diabetes. Therefore, future studies should thoroughly analyze the sex-specific metabolic determinants to propose new therapeutic targets. With current medicine tending toward more personalized care of patients, we finally propose to discuss the importance of sex as determinant in the treatment of diabetes-associated cardiac diseases to promote a more systemic inclusion of both males and females in clinical and preclinical studies.

The effects of interval training on peripheral brain derived neurotrophic factor (BDNF) in young adults: a systematic review and meta-analysis

The aim of the current meta-analysis was to determine the effects of acute and chronic interval training (IT) on serum and plasma BDNF concentrations in healthy young adults. A literature search was performed using six databases until February 2020. The TESTEX scale was used to assess the quality of studies. Effect sizes (ES) were computed and two-tailed α values < 0.05 and non-overlapping 95% confidence intervals (95% CI) were considered statistically significant. Heterogeneity, inconsistency (I²), and small-study effects using the Luis Furuya-Kanamori (LFK) index were examined. Fifteen studies (n = 277 participants, age = 24 ± 3 years) were included. The overall effects of IT on circulating BDNF concentrations were moderate and significant (ES = 0.62, 95% CI 0.00, 1.24, heterogeneous (p < 0.001), highly inconsistent (I² = 90%), and with major asymmetry (LFK index = 2.76). The acute effect of IT on peripheral BDNF levels was large and significant (ES = 1.10, 95% CI 0.07, 2.14), heterogeneous (p < 0.001), highly inconsistent (I² = 92%), and with major asymmetry (LFK index = 3.34). The chronic effect of IT on circulating BDNF was large and significant (ES = 0.93, 95% CI 0.40, 1.46), heterogeneous (p < 0.001), with moderate inconsistency (I² = 70%), and minor asymmetry (LFK index = 1.21). Acute and chronic IT elicited a moderate increase in serum and plasma BDNF concentrations in a healthy young population.

K-Means Clustering to Elucidate Vulnerable Subpopulations Among Medicare Patients Undergoing Total Joint Arthroplasty

BACKGROUND

The role of preoperative laboratory values for risk stratification following joint arthroplasty is currently ambiguous. In order to improve upon existing risk stratification within joint arthroplasty, this study sought to define novel phenotypes of total hip or total knee arthroplasty patients based entirely on preoperative laboratory measures. These phenotypes ("clusters") were compared to elucidate statistically and clinically significant differences in outcomes.

METHODS

A total of 134,252 patients were gathered from the National Surgical Quality Improvement Program database between 2005 and 2015. "K-means" with 3 clusters was applied using 9 preoperative laboratory values: sodium, blood urea nitrogen (BUN), creatinine, albumin, bilirubin, white blood cell count, hematocrit, platelet count, and international normalized ratio of prothrombin values (INR). Outcome measures included 30-day readmissions, severe adverse events, and discharge to nonhome.

RESULTS

Cluster 2 was characterized by elevated preoperative BUN, creatinine, and INR and demonstrated almost twice the rate of adverse events (3.52% vs 2.20% and 2.22%), 30-day readmissions (6.39% vs 3.31% and 3.71%), and discharge to nonhome (47.97% vs 30.50% and 35.85%). Cluster 3 was characterized by a slightly higher risk of discharge to nonhome than cluster 1 and was overwhelmingly female (79.5% female, 35.8% discharge to nonhome). Cluster 1 represents the lowest-risk subgroup, experiencing the lowest rates of readmissions, adverse events, and discharge to nonhome.

CONCLUSION

Preoperative laboratory values, namely BUN, creatinine, and INR, are useful in identifying patients at risk of adverse outcomes. This analysis supports the existing surgical literature pushing for preoperative hydration as a targeted intervention to expedite recovery.

High Mean Platelet Volume Associates with In-Hospital Mortality in Severe Pneumonia Patients

Background

Although mean platelet volume (MPV) appears to be associated with poor outcome of pneumonia, the relationship between MPV and in-hospital mortality is unclear in severe pneumonia (SP) patients.

Methods

In this retrospective cohort study, 115 SP patients from June 1st, 2016, to September 29th, 2019, were included and divided into two groups. The primary outcome was in-hospital mortality. The receiver operating characteristic (ROC) curve was performed to assess the predictive ability for in-hospital mortality. Kaplan-Meier cumulative incidence curves were applied to observe the incidence of mortality. Multivariable Cox regression analyses were used to evaluate the hazard ratios (HRs). Besides, a formal test for interaction was investigated to analyze the relationship between MPV and sex.

Results

During the course of hospitalization, 63 cases of mortality were recorded. ROC analysis suggested that MPV had a modest power for predicting in-hospital mortality (AUC = 0.723, 95% CI: 0.628-0.818, P < 0.001). Yet the cutoff value of MPV was 10.5 (sensitivity = 73.02%; specificity = 73.08%). Compared to the low-MPV group, the high-MPV group had significantly increased in-hospital mortality (log-rank test = 13.501, P < 0.001), while the adjusted Cox model indicated that the high-MPV group was associated with an elevated risk of in-hospital mortality (HR: 2.267, 95% CI: 1.166-4.406, P = 0.016). Moreover, analyses of in-hospital mortality suggested a significant interaction between optimal MPV level and sex (P = 0.011). In a multivariate Cox model which included females only, a high MPV level was associated with increased risk of in-hospital mortality (HR: 11.387, 95% CI: 1.767-73.380, P = 0.011).

Conclusion

High MPV level is an independent risk factor for in-hospital mortality in patients with SP.

Hydroxyvitamin D Serum Levels are Negatively Associated with Platelet Number in a Cohort of Subjects Affected by Overweight and Obesity

BACKGROUND

Hypovitaminosis D and higher platelet numbers are emerging as cardiovascular risk factors, in particular in obese subjects.

METHODS

This observational study was aimed at investigating the relationship between platelet number and serum 25-hydroxyvitamin D (25(OH)D) levels in a cohort of individuals affected by overweight and obesity (body mass index (BMI) ≥ 25 Kg/m²). A sample of 341 subjects (248 women, 93 men), aged 18-71 years, taking no medication, was examined. Anthropometric, hormone, metabolic and common routine hematochemical parameters were examined and evaluated in association with platelet count and serum 25(OH)D levels.

RESULTS

Platelet numbers were inversely related to age (p < 0.04), 25(OH)D (p < 0.05) and uric acid (p < 0.04) levels, and directly associated with white blood cells (p < 0.01), Thyroid Stimulating Hormone (TSH) (p < 0.04), insulin levels (p < 0.002) and Homeostasis Model Assessment - Insulin Resistance (HOMA-IR) (p < 0.002). We applied statistical regression models to examine the relationship between platelet count (dependent variable) and parameters that had univariate associations with platelet numbers, showing that the association between platelet count and 25(OH)D was not confirmed. Moreover, vitamin D showed a negative independent association with BMI, diastolic blood pressure and serum insulin levels.

CONCLUSIONS

This study indicates, for the first time, that vitamin D deficiency is associated with a parallel increase in platelet number, suggesting that higher platelet numbers may be one of the possible mechanisms leading to a greater cardiovascular risk in obese subjects. It also shows that vitamin D deficiency, a common condition in obesity, has independent associations with higher BMI, diastolic blood pressure and serum insulin levels.