Existence of a microRNA pathway in anucleate platelets

From reticulated platelets to immature platelet fraction: structure, function, and clinical applications

In comparison to mature platelets, reticulated platelets (RPs) are newly released from the bone marrow and exhibit a larger size, higher reactivity, and a greater quantity of RNA, and can be an agile indicator of platelet turnover. The transcriptome associated with platelet function is significantly upregulated in RPs, which is a possible explanation for RPs intrinsic hyper-reactivity. We presented a comprehensive overview of the detection techniques for RPs. Current methods to quantify RPs in clinical routine are flow cytometry and fully automated hematology analyzers (Sysmex-XE/XN, Abbott, ADVIA, Mindray), which make the detection of RPs simpler, faster and more affordable. The proportion of RPs increased in the circulation has potential diagnostic and prognostic values in multiple clinical settings (risk stratification in cardiovascular diseases, the effect on antiplatelet drugs, differential diagnosis of thrombocytopenia, monitor platelet recovery after bone marrow or stem cell transplantation, and other diseases). There have been several studies focusing on RPs in recent years, particularly in cardiovascular disease and thrombocytopenia. In this review we summarizes the current study with regard to RPs and discuss their likely contribution in clinical routine.

The Role of Platelet-Neutrophil Interactions in Driving Autoimmune Diseases

Platelets and neutrophils are among the most abundant cell types in peripheral blood. Beyond their traditional roles in thrombosis and haemostasis, they also play an active role in modulating immune responses. Current knowledge on the role of platelet-neutrophil interactions in the immune system has been rapidly expanding. Notably, circulating platelet-neutrophil complexes (PNCs) have been widely detected in various inflammatory diseases and infections, closely associated with inflammatory processes affecting multiple organs. These findings emphasise the critical role of platelet-neutrophil interactions in driving and sustaining inflammatory responses. In this review, we elucidate the mechanisms by which neutrophils and platelets physically interact, leading to mutual activation. Additionally, activated platelets release pro-inflammatory factors that further modulate neutrophil effector functions, enhancing their immune response capabilities. We highlight the role of platelets in promoting the formation of neutrophil extracellular traps (NETs), which, in turn, promote local platelet activation, thereby exacerbating the immune response and sustaining chronic inflammation. Furthermore, we review current evidence on the role of platelet-neutrophil interactions in common autoimmune diseases such as systemic lupus erythematosus (SLE), systemic sclerosis (SSc), and rheumatoid arthritis (RA). Finally, we identify gaps in understanding the mechanisms of these interactions in the context of other autoimmune diseases and underscore the potential of targeting platelets and neutrophils as a therapeutic strategy for these conditions.

Platelet miRNAs as early biomarkers for progression of idiopathic REM sleep behavior disorder to a synucleinopathy

Individuals diagnosed with isolated REM sleep behavior disorder (IRBD) have a high risk of developing Lewy body disorders (LBD), mainly Parkinson's disease (PD) or dementia with Lewy bodies (DLB). As we have previously identified seven platelet-derived miRNAs as potential biomarkers for DLB, in this pilot study we aimed to investigate whether specific expression changes of these miRNAs are also present in IRBD. RNA was obtained from platelets of individuals with IRBD (n = 29) and controls (n = 34), and miRNA levels were determined with a miRCURY LNA miRNA Custom PCR Panel. miRNA interactomes of deregulated miRNAs were determined, and mRNA quantification of miRNA target genes was carried out using real-time PCR and the ΔΔCt method. We found that the expression of hsa-miR- 139 - 5p (p = 0.010) and hsa-miR- 142 - 3p (p = 0.017) was diminished, while hsa-miR- 191 - 5p (p = 0.023) was increased in platelets of IRBD patients compared with controls. Interactome analysis of these miRNAs showed that hsa-miR- 142 - 3p regulates genes related to the structure and maintenance of the cytoskeleton. Of the 15 genes expressed in platelets, the expression of WASL, a gene involved in actin filament organization, was increased in platelets of IRBD patients. Additionally, WASL expression correlated inversely with hsa-miR- 142 - 3p expression. Since the interactomes of hsa-miR- 139 - 5p and hsa-miR- 191 - 5p play a role in several cancer types, their expression was not addressed. Changes in hsa-miR- 142 - 3p, hsa-miR- 139 - 5p, and hsa-miR- 191 - 5p expression were found in IRBD platelets and might represent early biomarkers for LBD involving cytoskeleton dysfunction. Increased expression of WASL could indicate that altered platelet activation occurs early during the development of LBD.

Evaluation of response to clopidogrel in patients with CYP2C19*2/*3 polymorphisms and its association with miR-19b expression

BACKGROUND

Clopidogrel is a widely used antiplatelet drug for treating acute coronary syndrome. Its metabolism primarily involves the CYP2C19 isoenzyme, with CYP2C192 and CYP2C193 alleles associated with reduced metabolic activity. MicroRNAs, particularly miR-19b, have been linked to cardiovascular disease, but their role in clopidogrel metabolism remains unclear.

METHODS

A cross-sectional study was conducted on 50 middle-aged patients on clopidogrel therapy. Platelet aggregation was measured using adenosine diphosphate-induced assays, while CYP2C19*2/*3 polymorphisms were analyzed via RFLP-PCR. The expression of miR-19b was assessed using Real Time-PCR. Statistical analyses were performed to evaluate the relationship between genetic variations, platelet aggregation, and miR-19b expression.

RESULTS

The study revealed that 68% of the patients had wild-type genotypes, while 26% had CYP2C19*1/3, 4% had CYP2C193/3, and 2% had CYP2C191/2 genotypes. Patients with CYP2C191/3 polymorphisms exhibited significantly higher mean platelet aggregation compared to those with wild-type genotypes, suggesting a reduced response to clopidogrel treatment. Additionally, the expression of miR-19b did not show significant variation across the different genotypes, indicating that miR-19b may not play a substantial role in clopidogrel metabolism.

CONCLUSION

Patients with CYP2C19*1/*3 polymorphisms have a reduced response to clopidogrel, emphasizing the importance of genetic testing to personalize antiplatelet therapy. The lack of association between miR-19b expression and clopidogrel metabolism suggests that miR-19b is not a critical factor in treatment response.

Establishment of a nomogram-based prognostic model (LASSO-Cox regression) for predicting platelet storage lesions under different storage conditions

Introduction

Platelet concentrates (PCs) are critical blood products used for transfusion, but stored platelets often experience quality deterioration, resulting in reduced efficacy post-transfusion. Currently, the lack of effective prediction models hinders the assessment of platelet storage quality. To address this, we developed a miRNA-based prognosis prediction model that comprehensively evaluates platelet quality under diverse storage conditions, offering valuable insights into platelet shelf life.

Methods

We enrolled 249 eligible PC samples, divided into a training dataset and internal validation dataset (7:3). Through microRNA sequencing, we identified 13 differentially expressed miRNAs with platelets storage lesions (PSLs). Leveraging the LASSO-Cox regression model, we constructed a nomogram-based classifier based on the association between miRNA expression and the duration of PSLs-free survival. Performance evaluation using measures like concordance index, area under the curve, calibration curves, and decision curve analyses to confirm the model's robustness.

Results

The nomogram classifier, incorporating miRNAs (miR-4485-3p, miR-12136, miR-25-5p, miR-148b-5p) and storage method, effectively categorized PCs into high-risk and low-risk groups. Notably, significant differences in PSLs-free survival were observed across all datasets, underscoring the precision and accuracy of our nomogram-based model.

Discussion

This innovative classifier provides clinicians with a reliable tool to predict PSLs occurrence in PCs stored under different methods, facilitating improved clinical decision-making.

Utilization of TEP miRNAs in tumor proliferation, diagnostic evaluation, therapeutic intervention, and prognostic assessment

According to the most recent 2022 statistics, China accounts for 4.82 million cancer patients, leading globally in prevalence. Early detection and intervention remain the most effective strategies for tumor prevention, treatment, and mortality reduction. There is an urgent need to enhance capabilities in cancer diagnosis and prevention. This study examines the association between tumor-educated platelet (TEP) microRNAs (miRNAs) and malignancies, as well as the role of TEP miRNAs in common cancers. TEP miRNAs offer significant advantages over tissue biopsies, conventional tumor biomarkers, and circulating miRNAs, including simplified sampling procedures, efficient monitoring, and longitudinal assessment of therapeutic dynamics. These advantages are instrumental in advancing tumor screening, diagnosis, treatment, and monitoring.

Unlocking the Potential of MicroRNA Expression: Biomarkers for Platelet Reactivity and Coronary Artery Disease

Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide, with platelet reactivity playing a central role in its pathogenesis. Recent research has identified microRNAs (miRNAs; miRs) as potential biomarkers for CAD, due to their ability to regulate platelet function and reactivity. This review focuses on four key miRNAs-miR-223, miR-126, miR-21, and miR-150-known to influence platelet reactivity and their implications in CAD. miR-223, which is highly expressed in platelets, has shown associations with CAD and myocardial infarction, while miR-126 has been linked to thrombus formation and vascular health. Additionally, miR-21 and miR-150 have also emerged as important players, with roles in platelet reactivity and cardiovascular outcomes. However, despite their potential, the use of miRNAs as clinical biomarkers faces several challenges, including variability in reported results across studies. These inconsistencies often arise from differences in sample material, preanalytical conditions, and normalization strategies. Furthermore, the influence of antiplatelet therapy on miRNA expression adds another layer of complexity, making it difficult to determine whether observed changes in miRNA levels are due to disease states or therapeutic interventions. This review therefore highlights the need for standardization in miRNA research to enhance the reliability of findings. By addressing these methodological challenges, miRNAs could become powerful tools in personalized medicine, aiding in the development of tailored therapeutic strategies for CAD patients and ultimately improving clinical outcomes.

Roles of miR-223 in Platelet Function and High On-Treatment Platelet Reactivity: A Brief Report and Review

BACKGROUND

Platelets are highly enriched in microRNAs (miRNAs), which are genomically encoded 19-25 nucleotide non-coding RNAs that target complementary mRNAs through total or near-total base pairing. MiR-223 is among the most abundant miRNAs in human and murine platelets, but despite ongoing investigations in recent years, miR-223 roles in platelet physiology and its putative roles in high on-treatment platelet reactivity (HTPR) remain controversial, as studies showed varying findings.

OBJECTIVES

In the current hybrid review/report, we aim to compare studies that investigated miR-223 in platelet function and HTPR. Additionally, we briefly report our own findings on murine miR-223-deficient platelets.

METHODS

We have thoroughly searched the literature and found three studies that investigated the roles of miR-223 in platelet function by utilizing miR-223 global knockout mice, and three studies that explored the association between miR-223 and residual platelet reactivity by measuring miR-223 levels in platelets of patients treated with clopidogrel for cardiac artery disease. We assessed platelet function in response to different agonists and evaluated P2y12 levels in male and female miR-223-deficient platelets.

RESULTS

Integrin activation and α granule secretion were similar between WT and KO platelets in response to all agonists in platelets from both female and male mice, although both genotypes showed elevated thrombin response in females compared to males.

CONCLUSIONS

In all studies, including ours, taken together, miR-233 appears to play a modest role in platelet function and development of HTPR.

Prognostic Value of Multiple Complete Blood Count-Derived Indices in Intermediate Coronary Lesions

Complete blood count (CBC)-derived indices have been proposed as reliable inflammatory biomarkers to predict outcomes in the context of coronary artery disease. These indices have yet to be thoroughly validated in patients with intermediate coronary stenosis. Our study included 1527 patients only with intermediate coronary stenosis. The examined variables were neutrophil-lymphocyte ratio (NLR), derived NLR, monocyte-lymphocyte ratio (MLR), platelet-lymphocyte ratio (PLR), systemic immune inflammation index (SII), system inflammation response index (SIRI), and aggregate index of systemic inflammation (AISI). The primary endpoint was the composite of major adverse cardiovascular events (MACEs), including all-cause death, non-fatal myocardial infarction, and unplanned revascularization. Over a follow-up of 6.11 (5.73-6.55) years, MACEs occurred in 189 patients. Receiver operator characteristic curve analysis showed that SIRI outperformed other indices with the most significant area under the curve. In the multivariable analysis, SIRI (hazard ratio [HR] 1.588, 95% confidence interval [CI] 1.138-2.212) and AISI (HR 1.673, 95% CI 1.217-2.300) were the most important prognostic factors among all the indices. The discrimination ability of each index was strengthened in patients with less burden of modifiable cardiovascular risk factors. SIRI also exhibited the best incremental value beyond the traditional cardiovascular risk model.

Argonaute2 modulates megakaryocyte development and sex-specific control of platelet protein expression and reactivity

Platelets are enriched in miRNAs and harbor Ago2 as the principal RNA silencing Argonaute. However, roles in thrombopoiesis and platelet function remain poorly understood. We generated megakaryocyte/platelet-specific Ago2-deleted (Ago2 KO) mice and assessed proteomic and functional effects. We predicted platelet hyperreactivity with Ago2 deletion due to large-scale upregulated protein expression. Platelet counts were normal. Mean volumes were increased, associated with larger, though fewer megakaryocytes. Ago2-deleted platelets from male mice showed hyperreactivity to thromboxane but not to other agonists compared to controls, whereas Ago2-deleted platelets from female mice showed normal reactivity. Ago2 KO mice displayed normal hemostasis and clot dynamics. Proteomes of Ago2-deleted and wild type platelets were mostly similar. However, Ago1 - undetectable in wild type platelets - was upregulated in Ago2-deleted platelets in both males and females, confirmed by immunoblotting. Female Ago2-deleted platelets selectively showed downregulation of a protein cohort established in breast cancer cells to be transcriptionally regulated by estrogen receptor-beta coupled to Ago2, whereas male Ago2-deleted platelets did not. Thus, Ago2 is important for platelet development and function, putatively partially rescued by upregulation of Ago1. Platelet reactivity controlled by Ago2 reflects sex-specific regulation of gene expression potentially at both transcriptional and translational levels in megakaryocytes and platelets.

Potential Player of Platelet in the Pathogenesis of Cardiotoxicity: Molecular Insight and Future Perspective

Cancer patients may encounter the onset of cardiovascular disease due to tumor advancement or chemotherapy, commonly known as "cardiotoxicity." In this respect, the conventional chemotherapy treatment protocol involves a mixture of different medications. These medications can be detrimental to cardiac tissue, consequently exposing the patient to the possibility of irreversible cardiac injury. The enhancement of oxidative stress and inflammation is an important mechanism of chemotherapeutic agents for developing cardiotoxicity. Regarding their dual pro- and anti-inflammatory functions, platelets can significantly influence the progression or suppression of cardiotoxicity. Therefore, the expression of platelet activatory markers can serve as valuable prognostic indicators for cardiotoxicity. The primary objective of this study is to examine the significance of platelets in cardiotoxicity and explore potential strategies that could effectively target malignant cells while minimizing their cytotoxic impact, such as cardiotoxicity and thrombosis.

Intraplatelet miRNA-126 regulates thrombosis and its reduction contributes to platelet inhibition

AIMS

MicroRNA-126 (miR-126), one of the most abundant microRNAs in platelets, is involved in the regulation of platelet activity and the circulating miR-126 is reduced during antiplatelet therapy. However, whether intraplatelet miR-126 plays a role in thrombosis and platelet inhibition remains unclear.

METHODS AND RESULTS

Here, using tissue-specific knockout mice, we reported that the deficiency of miR-126 in platelets and vascular endothelial cells significantly prevented thrombosis and prolonged bleeding time. Using chimeric mice, we identified that the lack of intraplatelet miR-126 significantly prevented thrombosis. Ex vivo experiments further demonstrated that miR-126-deficient platelets displayed impaired platelet aggregation, spreading, and secretory functions. Next, miR-126 was confirmed to target phosphoinositol-3 kinase regulatory subunit 2 (PIK3R2) in platelet, which encodes a negative regulator of the phosphoinositide 3-kinase/protein kinase B pathway, enhancing platelet activation through activating the integrin αIIbβ3-mediated outside-in signalling. After undergoing myocardial infarction (MI), chimeric mice lacking intraplatelet miR-126 displayed reduced microvascular obstruction and prevented MI expansion in vivo. In contrast, overexpression of miR-126 by the administration of miR-126 agonist (agomiR-126) in wild-type mice aggravated microvascular obstruction and promoted MI expansion, which can be almost abolished by aspirin administration. In patients with cardiovascular diseases, antiplatelet therapies, either aspirin alone or combined with clopidogrel, decreased the level of intraplatelet miR-126. The reduction of intraplatelet miR-126 level was associated with the decrease in platelet activity.

CONCLUSION

Our murine and human data reveal that (i) intraplatelet miR-126 contributes to platelet activity and promotes thrombus formation, and (ii) the reduction of intraplatelet miR-126 contributes to platelet inhibition during antiplatelet therapy.

Expression quantitative trait locus mapping of extracellular microRNAs in human plasma

MicroRNAs, crucial in regulating protein-coding gene expression, are implicated in various diseases. We performed a genome-wide association study of plasma miRNAs (ex-miRNAs) in 3,743 Framingham Heart Study (FHS) participants and identified 1,027 cis-ex-miRNA-eQTLs (cis-exQTLs) for 37 ex-miRNAs, with 55% replication in an independent study. Colocalization analyses suggested potential genetic coregulation of ex-miRNAs with whole blood mRNAs. Mendelian randomization indicated 29 ex-miRNAs potentially influencing 35 traits. Notably, the chromosome 14q23 and 14q32 miRNA clusters emerged as the top signal, contributing over 50% of the significant cis-exQTL results, and were associated with a diverse range of traits including platelet count. Correlations of 10 ex-miRNAs (such as miR-376c-3p) in 14q32 with platelet count and volume were confirmed in FHS participants. These findings shed light on the genetic basis of ex-miRNA expression and their involvement in complex traits.

Considering Context-Specific microRNAs in Ischemic Stroke with Three "W": Where, When, and What

MicroRNAs are short non-coding RNA molecules that function as critical regulators of various biological processes through negative regulation of gene expression post-transcriptionally. Recent studies have indicated that microRNAs are potential biomarkers for ischemic stroke. In this review, we first illustrate the pathogenesis of ischemic stroke and demonstrate the biogenesis and transportation of microRNAs from cells. We then discuss several promising microRNA biomarkers in ischemic stroke in a context-specific manner from three dimensions: biofluids selection for microRNA extraction (Where), the timing of sample collection after ischemic stroke onset (When), and the clinical application of the differential-expressed microRNAs during stroke pathophysiology (What). We show that microRNAs have the utilities in ischemic stroke diagnosis, risk stratification, subtype classification, prognosis prediction, and treatment response monitoring. However, there are also obstacles in microRNA biomarker research, and this review will discuss the possible ways to improve microRNA biomarkers. Overall, microRNAs have the potential to assist clinical treatment, and developing microRNA panels for clinical application is worthwhile.

Circulating microRNAs targeting coagulation and fibrinolysis in patients with severe COVID-19

BACKGROUND

Coronavirus-19 disease (COVID-19) frequently causes coagulation disturbances. Data remains limited on the effects of microRNAs (miRNAs) on coagulation during COVID-19 infection. We aimed to analyze the comprehensive miRNA profile as well as coagulation markers and blood count in hospitalized COVID-19 patients.

METHODS

Citrated plasma samples from 40 patients (24 men and 16 women) hospitalized for COVID-19 were analyzed. Basic coagulation tests, von Willebrand factor (VWF), ADAMTS13, blood count, C-reactive protein, and 27 miRNAs known to associate with thrombosis or platelet activation were analyzed. MiRNAs were analyzed using quantitative reverse transcription polymerase chain reaction (RT qPCR), with 10 healthy controls serving as a comparator.

RESULTS

Among the patients, 15/36 (41%) had platelet count of over 360 × 109/L and 10/36 (28%) had low hemoglobin of < 100 g/L, while 26/37 (72%) had high VWF of over 200 IU/dL. Patients had higher levels of the miRNAs miR-27b-3p, miR-320a-3p, miR-320b-3p, and miR-424-5p, whereas levels of miR-103a-3p and miR-145-5p were lower than those in healthy controls. In total, 11 miRNAs were associated with platelet count. Let-7b-3p was associated with low hemoglobin levels of < 100 g/L. miR-24-3p, miR-27b-3p, miR-126-3p, miR-145-5p and miR-338-5p associated with high VWF.

CONCLUSION

COVID-19 patients differentially express miRNAs with target genes involved in fibrinolysis inhibition, coagulation activity, and increased inflammatory response. These findings support the notion that COVID-19 widely affects hemostasis, including platelets, coagulation and fibrinolysis.

High circulating microRNA-197 levels are associated with an increased risk of incident stroke among elderly survivors of the Great East Japan Earthquake

BACKGROUND

Incidence of ischemic stroke increased after natural disasters. Therefore, it is important to establish a means of identifying high-risk populations for incident stroke. We performed a prospective cohort study to examine whether these three cardiovascular disease-related miRNAs (miR-126, miR-197, and miR-223) are associated with incident stroke among elderly survivors of the Great East Japan Earthquake.

METHOD

This cohort study was conducted using the data of 1192 survivors of the Great East Japan Earthquake over 60-years old who underwent a health check-up in December 2011. We followed up participants to record stroke cases until the end of 2016. We measured serum miRNAs by quantitative real-time polymerase chain reaction. HRs for incident stroke were estimated by Cox proportional hazard regression analyses.

RESULT

The serum miR-197 level was significantly associated with the incident stroke; the HR per one standard deviation change in the miR-197 level was 1.65 (95% confidence interval: 1.19 - 2.30). In contrast, the levels of miR-126 and miR-223 were not associated with the incident stroke.

CONCLUSION

We found that a higher miR-197 level is associated with an increased risk of incident stroke; thus, miR-197 is expected to be useful as a predictive biomarker.

Dietary omega-3 fatty acids modulate the production of platelet-derived microvesicles in an in vivo inflammatory arthritis model

PURPOSE

The aim of this study was to investigate the effects of different ω-3 polyunsaturated fatty acid (PUFA) enriched diets, including a novel renewable plant source of ω-3 fatty acids (Buglossoides arvensis), on the development and progression of rheumatoid arthritis (RA).

METHODS

RA was induced in mice consuming experimental diets using the K/BxN model. The experimental diets consisted of either a western control diet (control), diets containing B. arvensis oil or fish oil. The effects of the diets on platelets, platelet microvesicles (PMVs), and inflammatory markers such as clinical index, ankle thickness and cytokine/chemokine release were measured.

RESULTS

While ω-3 PUFA-enriched diets did not prevent the development of arthritis in the K/BxN model, a significant decrease in ankle swelling was observed compared to the control group. Platelets isolated from mice consuming either low content of B. arvensis oil or fish oil diets exhibited significantly decreased PMVs production compared to mice consuming the control diet.

CONCLUSION

Our study provides insight into the contribution of ω-3 PUFA supplementation in modulating the pro-inflammatory phenotype of platelets in RA pathology. Furthermore, our study suggests that low concentrations of dietary B. arvensis oil may have similar anti-inflammatory potential seen with dietary fish oil supplementation.

New Perspectives and Prospects of microRNA Delivery in Diabetic Wound Healing

The remarkable potential of microRNAs (miRNAs) as a class of biotherapeutic agents in the treatment of diverse pathological conditions has garnered significant interest in recent years. To heal both acute and chronic wounds, miRNAs work by post-transcriptionally controlling various proteins and the pathways that are linked to them. Diabetes mellitus predisposes to several macro- and microvascular defects of end organs such as atherosclerosis, peripheral artery disease, retinopathy, nephropathy, neuropathy, and impaired wound healing. Here, miRNAs emerge as a beacon of hope, with the capacity to heal diabetic wounds by precisely modulating the expression of genes involved in the healing process. Despite the therapeutic promise, the journey to realizing the full potential of miRNAs is fraught with challenges. Their intrinsic instability and the inefficient delivery into target cells pose significant barriers to their clinical application. Consequently, a major focus of current research is the discovery of novel miRNAs and the development of innovative delivery systems that can effectively transport these nucleic acids into the cells where they are needed most. This review delves into the intricate roles that miRNAs play at various stages of diabetic wound healing, providing a comprehensive overview of the latest research findings. The review also addresses the obstacles and opportunities that come with translating miRNA-based strategies into clinical practice, offering a critical assessment of the field's advancements and the hurdles that remain to be overcome. SIGNIFICANCE STATEMENT: The potential of microRNA delivery using new biological or nonbiological carriers may create a revolutionary treatment method for chronic wounds of diabetes.

Platelet Storage-Problems, Improvements, and New Perspectives

Platelet transfusions are routine procedures in clinical treatment aimed at preventing bleeding in critically ill patients, including those with cancer, undergoing surgery, or experiencing trauma. However, platelets are susceptible blood cells that require specific storage conditions. The availability of platelet concentrates is limited to five days due to various factors, including the risk of bacterial contamination and the occurrence of physical and functional changes known as platelet storage lesions. In this article, the problems related to platelet storage lesions are categorized into four groups depending on research areas: storage conditions, additive solutions, new testing methods for platelets (proteomic and metabolomic analysis), and extensive data modeling of platelet production (mathematical modeling, statistical analysis, and artificial intelligence). This article provides extensive information on the challenges, potential improvements, and novel perspectives regarding platelet storage.

Ticagrelor downregulates the expression of proatherogenic and proinflammatory miR125-b compared to clopidogrel: A randomized, controlled trial

BACKGROUND

Platelet P2Y12 antagonist ticagrelor reduces cardiovascular mortality after acute myocardial infarction (AMI) compared to clopidogrel, but the underlying mechanism is unknown. Because activated platelets release proatherogenic and proinflammatory microRNAs, including miR-125a, miR-125b and miR-223, we hypothesized that the expression of these miRNAs is lower on ticagrelor, compared to clopidogrel.

OBJECTIVES

We compared miR-125a, miR-125b and miR-223 expression in plasma of patients after AMI treated with ticagrelor or clopidogrel.

METHODS

After percutaneous coronary intervention on acetylsalicylic acid and clopidogrel, 60 patients with first AMI were randomized to switch to ticagrelor or to continue with clopidogrel. Plasma expression of miR-223, miR-125a-5p, miR-125b was measured using quantitative polymerase chain reaction at baseline and after 72 h and 6 months of treatment with ticagrelor or clopidogrel in patients and one in 30 healthy volunteers. Multiple electrode aggregometry using ADP test was used to determine platelet reactivity in response to P2Y12 inhibitors.

RESULTS

Expression of miR-125b was higher in patients with AMI 72 h and 6 months, compared to healthy volunteers (p = 0.001), whereas expression of miR-125a-5p and miR-223 were comparable. In patients randomized to ticagrelor, expression of miR-125b decreased at 72 h (p = 0.007) and increased back to baseline at 6 months (p = 0.005). Expression of miR-125a-5p and miR-223 was not affected by the switch from clopidogrel to ticagrelor.

CONCLUSIONS

Ticagrelor treatment leads to lower plasma expression of miR-125b after AMI, compared to clopidogrel. Higher expression of miR-125b might explain recurrent thrombotic events and worse clinical outcomes in patients treated with clopidogrel, compared to ticagrelor.

Platelet-derived microvesicles isolated from type-2 diabetes mellitus patients harbour an altered miRNA signature and drive MDA-MB-231 triple-negative breast cancer cell invasion

The underlying causes of breast cancer are diverse, however, there is a striking association between type 2 diabetes and poor patient outcomes. Platelet activation is a common feature of both type 2 diabetes and breast cancer and has been implicated in tumourigenesis through a multitude of pathways. Here transcriptomic analysis of type 2 diabetes patient-derived platelet microvesicles revealed an altered miRNA signature compared with normoglycaemic control patients. Interestingly, interrogation of these data identifies a shift towards an oncogenic signature in type 2 diabetes-derived platelet microvesicles, with increased levels of miRNAs implicated in breast cancer progression and poor prognosis. Functional studies demonstrate that platelet microvesicles isolated from type 2 diabetes patient blood are internalised by triple-negative breast cancer cells in vitro, and that co-incubation with type 2 diabetes patient-derived platelet microvesicles led to significantly increased expression of epithelial to mesenchymal transition markers and triple-negative breast cancer cell invasion compared with platelet microvesicles from healthy volunteers. Together, these data suggest that circulating PMVs in type 2 diabetes patients may contribute to the progression of triple-negative breast cancer.

Influence of Genetic and Epigenetic Factors of P2Y12 Receptor on the Safety and Efficacy of Antiplatelet Drugs

PURPOSE

P2Y12 receptor inhibitors are drugs that decrease the risk of stent thrombosis and lower the long-term risk of non-stent-related myocardial infarction and stroke. They inhibit the binding of adenosine diphosphate (ADP) to the P2Y12 receptor and effectively reduce platelet reactivity. However, considerable variability in the pharmacodynamics response contributes to a failure of antiplatelet therapy; this phenomenon is especially notorious for older drugs, such as clopidogrel. Some genetic polymorphisms associated with these drugs' metabolic pathway, especially in the CYP2C19 gene, can significantly decrease antiplatelet efficacy. There are few reports on the variability stemming from the target of this drug class that is the P2Y12 receptor itself.

RESULTS AND CONCLUSION

This review summarizes the results of research that focus on the influence of P2Y12 genetic polymorphisms on the pharmacodynamics and the efficacy of P2Y12 inhibitors. We found that the conclusions of the studies are unequivocal, and despite several strong candidates, such as G52T (rs6809699) or T744C (rs2046934), they may not be independent predictors of the inadequate response to the drug. Most probably, P2Y12 genetic polymorphisms contribute to the effect exerted by other gene variants (such as CYP2C19*2/*3/*17), drug interactions, or patient habits, such as smoking. Also, epigenetic modifications, such as methylation or miRNA levels, may play a role in the efficacy of antiplatelet treatment.

microRNAs and thrombo-inflammation: relationship in sight

PURPOSE OF REVIEW

Thrombo-inflammation is a multifaceted pathologic process involving various cells such as platelets, neutrophils, and monocytes. In recent years, microRNAs have been consistently implicated as regulators of these cells.

RECENT FINDINGS

MicroRNAs play a regulatory role in several platelet receptors that have recently been identified as contributing to thrombo-inflammation and neutrophil extracellular trap (NET) formation. In addition, a growing body of evidence has shown that several intracellular and extracellular microRNAs directly promote NET formation.

SUMMARY

Targeting microRNAs is a promising therapeutic approach to control thrombosis in patients with both infectious and noninfectious inflammatory diseases. Future research efforts should focus on elucidating the specific roles of microRNAs in thrombo-inflammation and translating these findings into tangible benefits for patients.

Platelet-enriched microRNAs as novel biomarkers in atherosclerotic and cardiovascular disease patients

BACKGROUND

Cardiovascular disease (CVD) is a global health challenge. Various studies have shown that genetic and environmental factors play roles in the development and progression of CVD. Small non-coding RNAs, namely microRNAs (miRs), regulate gene expression and have key roles in essential cellular processes such as apoptosis, cell cycle, differentiation, and proliferation. Currently, clinical studies highlight the critical role of platelets and miRs in coronary thrombosis, atherosclerosis, and CVD.

METHODS

Using search engines such as PubMed and Scopus, articles studying platelet miRs and their effects on atherosclerosis and cardiovascular disease were reviewed.

RESULTS

This article presents a comprehensive analysis of the association of platelet-related miRs as prognostic, diagnostic, and therapeutic biomarkers with the pathogenesis of atherosclerosis and cardiovascular disease.

CONCLUSION

Taken together, data show that platelet-related miRs not only play important roles in the initial development of atherosclerosis and cardiovascular disease (CVD), but they are also considered prognostic and diagnostic biomarkers in CVD.

Platelet microRNAs as Potential Novel Biomarkers for Antiplatelet Therapy with P2Y12 Inhibitors and Their Association with Platelet Function

INTRODUCTION

Patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI) require dual antiplatelet therapy (DAPT). However, the response to treatment can vary considerably. Certain platelet microRNAs (miRs) are suspected to predict DAPT response and influence platelet function. This study aimed to analyze selected miRs' expressions and compare them among patients treated with different P2Y12 inhibitors while assessing their association with platelet activity and turnover parameters.

MATERIALS AND METHODS

We recruited 79 ACS patients post-PCI treated with clopidogrel, ticagrelor, or prasugrel, along with 18 healthy volunteers. Expression levels of miR-126-3p, miR223-3p, miR-21-5p, miR-197-3p, and miR-24-3p, as well as immature platelet fraction (IPF) and ADP-induced platelet reactivity, were measured and compared between groups.

RESULTS

Analyses revealed significantly lower expressions of miR-126-3p, miR-223-3p, miR-21-5p, and miR-197-3p in patients treated with ticagrelor, compared to clopidogrel (fold changes from -1.43 to -1.27, p-values from 0.028 to 0.048). Positive correlations were observed between platelet function and the expressions of miR-223-3p (r = 0.400, p = 0.019) and miR-21-5p (r = 0.423, p = 0.013) in patients treated with potent drugs. Additionally, miR-24-3p (r = 0.411, p = 0.012) and miR-197-3p (r = 0.333, p = 0.044) showed correlations with IPF.

CONCLUSIONS

The identified platelet miRs hold potential as biomarkers for antiplatelet therapy. (ClinicalTrials.gov number, NCT06177587).

Platelet protein synthesis, regulation, and post-translational modifications: mechanics and function

Dogma had been firmly entrenched in the minds of the scientific community that the anucleate mammalian platelet was incapable of protein biosynthesis since their identification in the late 1880s. These beliefs were not challenged until the 1960s when several reports demonstrated that platelets possessed the capacity to biosynthesize proteins. Even then, many still dismissed the synthesis as trivial and unimportant for at least another two decades. Research in the field expanded after the 1980s and numerous reports have since been published that now clearly demonstrate the potential significance of platelet protein synthesis under normal, pathological, and activating conditions. It is now clear that the platelet proteome is not a static entity but can be altered slowly or rapidly in response to external signals to support physiological requirements to maintain hemostasis and other biological processes. All the necessary biological components to support protein synthesis have been identified in platelets along with post-transcriptional processing of mRNAs, regulators of translation, and post-translational modifications such as glycosylation. The last comprehensive review of the subject appeared in 2009 and much work has been conducted since that time. The current review of the field will briefly incorporate the information covered in earlier reviews and then bring the reader up to date with more recent findings.

Circulating endothelial extracellular vesicle signatures correspond with ICU requirement: an exploratory study in COVID-19 patients

Extracellular vesicles (EVs) represent nanometer-sized, subcellular spheres, that are released from almost any cell type and carry a wide variety of biologically relevant cargo. In severe cases of coronavirus disease 2019 (COVID-19) and other states of systemic pro-inflammatory activation, EVs, and their cargo can serve as conveyors and indicators for disease severity and progression. This information may help distinguish individuals with a less severe manifestation of the disease from patients who exhibit severe acute respiratory distress syndrome (ARDS) and require intensive care measures. Here, we investigated the potential of EVs and associated miRNAs to distinguish normal ward patients from intensive care unit (ICU) patients (N = 10/group), with 10 healthy donors serving as the control group. Blood samples from which plasma and subsequently EVs were harvested by differential ultracentrifugation (UC) were obtained at several points in time throughout treatment. EV-enriched fractions were characterized by flow cytometry (FC), nanoparticle tracking analysis (NTA), and qPCR to determine the presence of selected miRNAs. Circulating EVs showed specific protein signatures associated with endothelial and platelet origin over the course of the treatment. Additionally, significantly higher overall EV quantities corresponded with increased COVID-19 severity. MiR-223-3p, miR-191-5p, and miR-126-3p exhibited higher relative expression in the ICU group. Furthermore, EVs presenting endothelial-like protein signatures and the associated miR-126-3p showed the highest area under the curve in terms of receiver operating characteristics regarding the requirement for ICU treatment. In this exploratory investigation, we report that specific circulating EVs and miRNAs appear at higher levels in COVID-19 patients, especially when critical care measures are indicated. Our data suggest that endothelial-like EVs and associated miRNAs likely represent targets for future laboratory assays and may aid in clinical decision-making in COVID-19.

Sources of variability in the human platelet transcriptome

Platelets are anucleated cells produced by megakaryocytes, from which they inherit all the components necessary to carry their functions. They circulate in blood vessels where they play essential roles in coagulation, wound repair or inflammation, and have been implicated in various pathological conditions such as thrombosis, viral infection or cancer progression. The importance of these cells has been established over a century ago, and effective anti-platelet medications with different mechanisms of action have since been developed. However, these therapies are not always effective and can incur adverse events, thus a better understanding of platelets molecular processes is needed to address these issues and improve our understanding of platelet functions. In recent years, an increasing number of studies have leveraged OMICs technologies to analyze their content and identify molecular signatures and mechanisms associated with platelet functions and platelet related disorders. In particular, the increased accessibility of microarrays and RNA sequencing opened the way for studies of the platelet transcriptome under a wide array of conditions. These studies revealed distinct expression profiles in diverse pathologies, which could lead to the discovery of novel biomarkers and therapeutic targets, and suggests a dynamic transcriptome that could influence platelet mechanisms. In this review, we highlight the different sources of transcript level variability in platelets while summarizing recent advances and discoveries from this emerging field.

B, Kappelmayer J, Kőszegi Z, Csanádi Z, Szük T. Technically Challenging Percutaneous Interventions of Chronic Total Occlusions Are Associated with Enhanced Platelet Activation

Percutaneous coronary intervention (PCI) is a frequently performed treatment option for recanalization in patients with chronic total occlusion (CTO). As CTO-PCIs are often complicated and challenging for interventionalists, the stressful and damaging nature of the procedure can be remarkable, thus platelets can be easily activated. Our aim was to investigate the effect of CTO-PCI on platelet activation and the expression of selected circulating microRNAs (miR) of platelet and endothelium origin after CTO-PCI. In this study, 50 subjects after CTO-PCI were enrolled. Blood samples were obtained before PCI, at 2 days and 3-6 months after the procedure to measure the degree of platelet activation and the level of plasma miR-223, miR-181b, and miR-126. Patients were divided based on the characteristics of the intervention. Patients with higher Japanese CTO scores and longer duration of PCI showed significantly elevated platelet P-selectin positivity (p = 0.004 and p = 0.013, respectively) 2 days after the procedure compared to pre-PCI and increased concentration of soluble P-selectin 3-6 months after the intervention (higher Japanese CTO score: p = 0.028 and longer duration of PCI: p = 0.023) compared to baseline values. Shorter total stent length caused a significantly lower miR-181b expression at 3-6 months after the intervention (p = 0.031), while no difference was observed in miR-223 and miR-126. One stent thrombosis occurred during the follow-up period. Although these technically challenging CTO-PCIs may cause enhanced platelet activation right after the intervention and long-term endothelial cell dysfunction, these interventions are not associated with more adverse clinical events.

Platelets and the Atherosclerotic Process: An Overview of New Markers of Platelet Activation and Reactivity, and Their Implications in Primary and Secondary Prevention

The key role played by platelets in the atherosclerosis physiopathology, especially in the acute setting, is ascertained: they are the main actors during thrombus formation and, thus, one of the major investigated elements related to atherothrombotic process involving coronary arteries. Platelets have been studied from different points of view, according with the technology advances and the improvement in the hemostasis knowledge achieved in the last years. Morphology and reactivity constitute the first aspects investigated related to platelets with a significant body of evidence published linking a number of their values and markers to coronary artery disease and cardiovascular events. Recently, the impact of genetics on platelet activation has been explored with promising findings as additional instrument for patient risk stratification; however, this deserves further confirmations. Moreover, the interplay between immune system and platelets has been partially elucidated in the last years, providing intriguing elements that will be basic components for future research to better understand platelet regulation and improve cardiovascular outcome of patients.

MiRNA-146a-A Key Player in Immunity and Diseases

miRNA-146a, a single-stranded, non-coding RNA molecule, has emerged as a valuable diagnostic and prognostic biomarker for numerous pathological conditions. Its primary function lies in regulating inflammatory processes, haemopoiesis, allergic responses, and other key aspects of the innate immune system. Several studies have indicated that polymorphisms in miRNA-146a can influence the pathogenesis of various human diseases, including autoimmune disorders and cancer. One of the key mechanisms by which miRNA-146a exerts its effects is by controlling the expression of certain proteins involved in critical pathways. It can modulate the activity of interleukin-1 receptor-associated kinase, IRAK1, IRAK2 adaptor proteins, and tumour necrosis factor (TNF) targeting protein receptor 6, which is a regulator of the TNF signalling pathway. In addition, miRNA-146a affects gene expression through multiple signalling pathways, such as TNF, NF-κB and MEK-1/2, and JNK-1/2. Studies have been carried out to determine the effect of miRNA-146a on cancer pathogenesis, revealing its involvement in the synthesis of stem cells, which contributes to tumourigenesis. In this review, we focus on recent discoveries that highlight the significant role played by miRNA-146a in regulating various defence mechanisms and oncogenesis. The aim of this review article is to systematically examine miRNA-146a's impact on the control of signalling pathways involved in oncopathology, immune system development, and the corresponding response to therapy.

Platelet formation and activation are influenced by neuronal guidance proteins

Platelets are anucleate blood cells derived from megakaryocytes. They link the fundamental functions of hemostasis, inflammation and host defense. They undergo intracellular calcium flux, negatively charged phospholipid translocation, granule release and shape change to adhere to collagen, fibrin and each other, forming aggregates, which are key to several of their functions. In all these dynamic processes, the cytoskeleton plays a crucial role. Neuronal guidance proteins (NGPs) form attractive and repulsive signals to drive neuronal axon navigation and thus refine neuronal circuits. By binding to their target receptors, NGPs rearrange the cytoskeleton to mediate neuron motility. In recent decades, evidence has indicated that NGPs perform important immunomodulatory functions and influence platelet function. In this review, we highlight the roles of NGPs in platelet formation and activation.

Left ventricular assist devices promote changes in the expression levels of platelet microRNAs

Introduction

MicroRNAs (miRs) emerged as promising diagnostic and therapeutic biomarkers in cardiovascular diseases. The potential clinical utility of platelet miRs in the setting of left ventricular assist device (LVAD) support is unexplored.

Methods

We prospectively measured the expression levels of 12 platelet miRs involved in platelet activation, coagulation, and cardiovascular diseases in LVAD patients by quantitative real-time polymerase chain reaction. Data were longitudinally measured before LVAD implant and after 1, 6, and 12 months of LVAD support, and compared with those measured in healthy volunteers (controls). In silico analysis was also performed to identify pathways targeted by differentially expressed miRs.

Results

Data from 15 consecutive patients and 5 controls were analyzed. Pre-implant expression levels of platelet miR-126, miR-374b, miR-223, and miR-320a were significantly different in patients vs. controls. The expression levels of platelet miR-25, miR-144, miR-320, and miR-451a changed significantly over the course of LVAD support; in silico analysis revealed that these miRs are implicated in both cardiac- and coagulation-associated pathways. Furthermore, the patients who suffered from bleeding (n = 5, 33%) had significantly higher pre-implant expression levels of platelet miR-151a and miR-454 with respect to the patients who did not. The same miRs were also differentially expressed in bleeders following LVAD implantation early before the clinical manifestation of the events.

Discussion

This study provides a proof-of-concept evidence of significant modulation of platelet miRs expression driven by LVADs. The possible existence of a platelet miRs signature predictive of the development of bleeding events warrants further validation studies.

CircPDS5B Reduction Improves Angiogenesis Following Ischemic Stroke by Regulating MicroRNA-223-3p/NOTCH2 Axis

Background and Objectives

Ischemic stroke (IS) is responsible for major causes of global death and disability, for which promoting angiogenesis is a promising therapeutic strategy. This study analyzed circular RNA PDS5B (circPDS5B) and its related mechanisms in angiogenesis in IS.

Methods

In the permanent middle cerebral artery occlusion (pMCAO) mouse model, circPDS5B, microRNA (miR)-223-3p, and NOTCH2 levels were checked. By testing neurologic function, neuronal apoptosis, and expression of angiogenesis-related proteins in pMCAO mice, the protective effects of circPDS5B knockdown were probed. In human brain microvascular endothelial cells (HBMECs) under oxygen-glucose deprivation (OGD) conditions, the effects of circPDS5B, miR-223-3p, and NOTCH2 on angiogenesis were studied by measuring cellular activities.

Results

The increase of circPDS5B and NOTCH2 expression and the decrease of miR-223-3p expression were examined in pMCAO mice. Reducing circPDS5B expression indicated protection against neurologic dysfunction, apoptosis, and angiogenesis impairment. For circPDS5B-depleted or miR-223-3p-restored HBMECs under OGD treatment, angiogenesis was promoted. MiR-223-3p inhibition-associated reduction of angiogenesis could be counteracted by knocking down NOTCH2. CircPDS5B depletion-induced angiogenesis in OGD-conditioned HBMECs was repressed after overexpressing NOTCH2.

Discussion

In IS, the expression of circPDS5B was upregulated, and miR-223-3p inhibited HBMECs activity and promoted NOTCH2 expression, thus promoting IS. CircPDS5B reduction improves angiogenesis following ischemic stroke by regulating microRNA-223-3p/NOTCH2 axis.

Inflammatory microRNAs in cardiovascular pathology: another brick in the wall

The regulatory role of microRNAs (miRNAs) is mainly mediated by their effect on protein expression and is recognized in a multitude of pathophysiological processes. In recent decades, accumulating evidence has interest in these factors as modulatory elements of cardiovascular pathophysiology. Furthermore, additional biological processes have been identified as new components of cardiovascular disease etiology. In particular, inflammation is now considered an important cardiovascular risk factor. Thus, in the present review, we will focus on the role of a subset of miRNAs called inflamma-miRs that may regulate inflammatory status in the development of cardiovascular pathology. According to published data, the most representative candidates that play functional roles in thromboinflammation are miR-21, miR-33, miR-34a, miR-146a, miR-155, and miR-223. We will describe the functions of these miRNAs in several cardiovascular pathologies in depth, with specific emphasis on the molecular mechanisms related to atherogenesis. We will also discuss the latest findings on the role of miRNAs as regulators of neutrophil extracellular traps and their impact on cardiovascular diseases. Overall, the data suggest that the use of miRNAs as therapeutic tools or biomarkers may improve the diagnosis or prognosis of adverse cardiovascular events in inflammatory diseases. Thus, targeting or increasing the levels of adequate inflamma-miRs at different stages of disease could help mitigate or avoid the development of cardiovascular morbidities.

The Novel Role of Noncoding RNAs in Modulating Platelet Function: Implications in Activation and Aggregation

It is currently believed that plaque complication, with the consequent superimposed thrombosis, is a key factor in the clinical occurrence of acute coronary syndromes (ACSs). Platelets are major players in this process. Despite the considerable progress made by the new antithrombotic strategies (P2Y12 receptor inhibitors, new oral anticoagulants, thrombin direct inhibitors, etc.) in terms of a reduction in major cardiovascular events, a significant number of patients with previous ACSs treated with these drugs continue to experience events, indicating that the mechanisms of platelet remain largely unknown. In the last decade, our knowledge of platelet pathophysiology has improved. It has been reported that, in response to physiological and pathological stimuli, platelet activation is accompanied by de novo protein synthesis, through a rapid and particularly well-regulated translation of resident mRNAs of megakaryocytic derivation. Although the platelets are anucleate, they indeed contain an important fraction of mRNAs that can be quickly used for protein synthesis following their activation. A better understanding of the pathophysiology of platelet activation and the interaction with the main cellular components of the vascular wall will open up new perspectives in the treatment of the majority of thrombotic disorders, such as ACSs, stroke, and peripheral artery diseases before and after the acute event. In the present review, we will discuss the novel role of noncoding RNAs in modulating platelet function, highlighting the possible implications in activation and aggregation.

The Acute and Chronic Effects of Resistance and Aerobic Exercise in Hemostatic Balance: A Brief Review

Hemostatic balance refers to the dynamic balance between blood clot formation (coagulation), blood clot dissolution (fibrinolysis), anticoagulation, and innate immunity. Although regular habitual exercise may lower the incidence of cardiovascular diseases (CVD) by improving an individual’s hemostatic profile at rest and during exertion, vigorous exercise may increase the risk of sudden cardiac death and venous thromboembolism (VTE). This literature review aims to investigate the hemostatic system’s acute and chronic adaptive responses to different types of exercise in healthy and patient populations. Compared to athletes, sedentary healthy individuals demonstrate similar post-exercise responses in platelet function and coagulatory and fibrinolytic potential. However, hemostatic adaptations of patients with chronic diseases in regular training is a promising field. Despite the increased risk of thrombotic events during an acute bout of vigorous exercise, regular exposure to high-intensity exercise might desensitize exercise-induced platelet aggregation, moderate coagulatory parameters, and up-regulate fibrinolytic potential via increasing tissue plasminogen activator (tPA) and decreasing plasminogen activator inhibitor (PAI-1) response. Future research might focus on combining different types of exercise, manipulating each training characteristic (frequency, intensity, time, and volume), or investigating the minimal exercise dosage required to maintain hemostatic balance, especially in patients with various health conditions.

MicroRNA: Crucial modulator in purinergic signalling involved diseases

Both microRNAs (miRNAs) and purinergic signalling are widely and respectively expressed in various tissues of different organisms and play vital roles in a variety of physiological and pathological processes. Here, we reviewed the current publications contributed to the relationship of miRNAs and purinergic signalling in cardiovascular diseases, gastrointestinal diseases, neurological diseases, and ophthalmic diseases. We tried to decode the miRNAs-purinergic signalling network of purinergic signalling involved diseases. The evidence indicated that more than 30 miRNAs (miR-22, miR-30, miR-146, miR-150, miR-155, miR-187, etc.) directly or indirectly modulate P1 receptors (A₁, A_2A, A_2B, A₃), P2 receptors (P2X1, P2X3, P2X4, P2X7, P2Y2, P2Y6, P2Y12), and ecto-enzymes (CD39, CD73, ADA2); P2X7 and CD73 could be modulated by multiple miRNAs (P2X7: miR-21, miR-22, miR-30, miR-135a, miR-150, miR-186, miR-187, miR-216b; CD73: miR-141, miR-101, miR-193b, miR-340, miR-187, miR-30, miR-422a); miR-187 would be the common miRNA to modulate P2X7 and CD73.

Expression of microRNA Predicts Cardiovascular Events in Patients with Stable Coronary Artery Disease

BACKGROUND

 New biomarkers are warranted to identify patients with coronary artery disease (CAD) at high risk of recurrent cardiovascular events. It has been reported that the expression of microRNAs (miRs) may influence the development of CAD.

OBJECTIVES

 We aimed to investigate whether the expression of selected candidate miRs is a predictor of cardiovascular events in a cohort of stable CAD patients.

METHODS

 We performed a single-center prospective study of 749 stable CAD patients with a median follow-up of 2.8 years. We investigated the expression of nine candidate miRs and their relation to cardiovascular events in this cohort. The primary endpoint was the composite of nonfatal myocardial infarction (MI), stent thrombosis (ST), ischemic stroke, and cardiovascular death. The composite of nonfatal MI and ST was analyzed as a secondary endpoint. Furthermore, nonfatal MI, ST, ischemic stroke, and all-cause mortality were analyzed as individual endpoints.

RESULTS

 Employing receiver operating characteristic curves, it was shown that compared with traditional cardiovascular risk factors alone, combining the expression of miR-223-3p with existing traditional cardiovascular risk factors increased the predictive value of ST (area under the curve: 0.88 vs. 0.77, p = 0.04), the primary composite endpoint (0.65 vs. 0.61, p = 0.049), and the secondary endpoint of the composite of nonfatal MI and ST (0.68 vs. 0.62, p = 0.04).

CONCLUSION

 Among patients with CAD, adding miR-223-3p expression to traditional cardiovascular risk factors may improve prediction of cardiovascular events, particularly ST. Clinical trials confirming these findings are warranted.

Ticagrelor Resistance in Cardiovascular Disease and Ischemic Stroke

Ticagrelor, acting as a reversible platelet aggregation inhibitor of P2Y12 receptors (P2Y12R), is regarded as one of the first-line antiplatelet drugs for acute cardiovascular diseases. Though the probability of ticagrelor resistance is much lower than that of clopidogrel, there have been recent reports of ticagrelor resistance. In this review, we summarized the clinical application of ticagrelor and then presented the criteria and current status of ticagrelor resistance. We further discussed the potential mechanisms for ticagrelor resistance in terms of drug absorption, metabolism, and receptor action. In conclusion, the incidences of ticagrelor resistance fluctuated between 0 and 20%, and possible mechanisms mainly arose from its absorption and receptor action. Specifically, a variety of factors, such as the drug form of ticagrelor, gut microecology, and the expression and function of P-glycoprotein (P-gp) and P2Y12R, have been shown to be associated with ticagrelor resistance. The exact mechanisms of ticagrelor resistance warrant further exploration, which may contribute to the diagnosis and treatment of ticagrelor resistance.

The Function and Regulation of Platelet P2Y12 Receptor

In addition to the key role in hemostasis and thrombosis, platelets have also been wildly acknowledged as immune regulatory cells and involving in the pathogenesis of inflammation-related diseases. Since purine receptor P2Y12 plays a crucial role in platelet activation, P2Y12 antagonists such as clopidogrel, prasugrel, and ticagrelor have been widely used in cardiovascular diseases worldwide in recent decades due to their potent antiplatelet and antithrombotic effects. Meanwhile, the role of P2Y12 in inflammatory diseases has also been extensively studied. Relatively, there are few studies on the regulation of P2Y12. This review first summarizes the various roles of P2Y12 in the process of platelet activation, as well as downstream effects and signaling pathways; then introduces the effects of P2Y12 in inflammatory diseases such as sepsis, atherosclerosis, cancer, autoimmune diseases, and asthma; and finally reviews the current researches on P2Y12 regulation.

Platelet-derived TLT-1 promotes tumor progression by suppressing CD8+ T cells

Current understanding of tumor immunosuppressive mechanisms forms the basis for modern day immunotherapies. Immunoregulatory role of platelets in cancer remains largely elusive. Platelets from non-small cell lung cancer (NSCLC) patients revealed a distinct activation phenotype. TREM-like transcript 1 (TLT-1), a platelet protein, was increased along with enhanced extracellular release from NSCLC platelets. The increased platelet TLT-1 was also evident in humanized mice with patient-derived tumors. In immunocompetent mice with syngeneic tumors, TLT-1 binding to T cells, in vivo, led to suppression of CD8 T cells, promoting tumor growth. We identified direct interaction between TLT-1 and CD3ε on T cells, implicating the NF-κB pathway in CD8 T cell suppression. Anti-TLT-1 antibody rescued patients' T cells from platelet-induced suppression ex vivo and reduced tumors in mice in vivo. Clinically, higher TLT-1 correlated with reduced survival of NSCLC patients. Our findings thus identify TLT-1 as a platelet-derived immunosuppressor that suppresses CD8 T cells and demonstrate its therapeutic and prognostic significance in cancer.

An Insight into Platelets at Older Age: Cellular and Clinical Perspectives

Higher access to medical care, advanced diagnostic tools, and overall public health improvements have favored increased humans lifespan. With a growing proportion of older adults, the associated costs to care for ageing-associated conditions will continue to grow. This chapter highlights recent cellular and clinical evidence of platelets at an older age, from the hyperreactive phenotype associated with thrombosis to the well-known hallmarks of ageing identifiable in platelets and their potential functional implications on platelets at an older age. Therefore, it is imperative to understand platelets' molecular and cellular mechanisms during ageing in health and disease. New knowledge will favor the development of new ways to prevent some of the age-associated complications where platelets are key players.

Contents in tumor-educated platelets as the novel biosource for cancer diagnostics

Liquid biopsy, a powerful non-invasive test, has been widely used in cancer diagnosis and treatment. Platelets, the second most abundant cells in peripheral blood, are becoming one of the richest sources of liquid biopsy with the capacity to systematically and locally respond to the presence of cancer and absorb and store circulating proteins and different types of nucleic acids, thus called "tumor-educated platelets (TEPs)". The contents of TEPs are significantly and specifically altered, empowering them with the potential as cancer biomarkers. The current review focuses on the alternation of TEP content, including coding and non-coding RNA and proteins, and their role in cancer diagnostics.

Plasma levels of platelet-enriched microRNAs change during antiplatelet therapy in healthy subjects

Platelets are the main effectors of primary hemostasis but also cause thrombosis in pathological conditions. Antiplatelet drugs are the cornerstone for the prevention of adverse cardiovascular events. Monitoring the extent of platelet inhibition is essential. Currently available platelet function tests come with constraints, limiting use in antiplatelet drug development as well as in clinical routine. With this study, we aim to investigate whether plasma miRNAs might be suitable biomarkers for monitoring antiplatelet treatment. Platelet-poor plasma was obtained from a trial including 87 healthy male volunteers that either received ticagrelor (n = 44) or clopidogrel (n = 43). Blood was collected before drug intake and after 2 h, 6 h, and 24 h. We measured a panel of 11 platelet-enriched miRNAs (thrombomiRs) by RT-qPCR and selected four biomarker candidates (i.e., miR-223-3p, miR-150-5p, miR-126-3p, miR-24-3p). To further characterize those miRNAs, we performed correlation analyses with the number of extracellular vesicles and clotting time dependent on procoagulant vesicles (PPL assay). We show that platelet-enriched miRNAs in the circulation are significantly reduced upon P2Y12-mediated platelet inhibition. This effect occurred fast, reaching its peak after 2 h. Additionally, we demonstrate that higher baseline levels of thrombomiRs are linked to a stronger reduction upon antiplatelet therapy. Finally, we show that miRNAs from our panel might be the cargo of platelet-derived and procoagulant vesicles. In conclusion, we provide evidence that thrombomiR levels change within 2 h after pharmacological platelet inhibition and circulate the body within platelet-derived and procoagulant extracellular vesicles, rendering them potential biomarker candidates for the assessment of in vivo platelet function.

Clinical Application of Serum microRNAs in Atherosclerotic Coronary Artery Disease

MicroRNAs (miRs) are promising diagnostic, prognostic and therapeutic biomolecules for atherosclerotic cardiovascular disease. Atherosclerotic occlusive disease concerns a large population of patients, carrying the highest incidence of fatal and non-fatal adverse events, such as myocardial infarction, ischemic stroke, and limb ischemia, worldwide. Consistently, miRs are involved in regulation and pathogenesis of atherosclerotic coronary artery disease (CAD), acute coronary syndromes (ACS), both with ST-segment (STEMI) and non-ST segment elevation myocardial infarctions (NSTEMI), as well as cardiac remodeling and fibrosis following ACS. However, the genetic and molecular mechanisms underlying adverse outcomes in CAD are multifactorial, and sometimes difficult to interpret for clinicians. Therefore, in the present review paper we have focused on the clinical meaning and the interpretation of various miRs findings, and their potential application in routine clinical practice.

Platelet in thrombo-inflammation: Unraveling new therapeutic targets

In the broad range of human diseases, thrombo-inflammation appears as a clinical manifestation. Clinically, it is well characterized in context of superficial thrombophlebitis that is recognized as thrombosis and inflammation of superficial veins. However, it is more hazardous when developed in the microvasculature of injured/inflamed/infected tissues and organs. Several diseases like sepsis and ischemia-reperfusion can cause formation of microvascular thrombosis subsequently leading to thrombo-inflammation. Thrombo-inflammation can also occur in cases of antiphospholipid syndrome, preeclampsia, sickle cell disease, bacterial and viral infection. One of the major contributors to thrombo-inflammation is the loss of normal anti-thrombotic and anti-inflammatory potential of the endothelial cells of vasculature. This manifest itself in the form of dysregulation of the coagulation pathway and complement system, pathologic platelet activation, and increased recruitment of leukocyte within the microvasculature. The role of platelets in hemostasis and formation of thrombi under pathologic and non-pathologic conditions is well established. Platelets are anucleate cells known for their essential role in primary hemostasis and the coagulation pathway. In recent years, studies provide strong evidence for the critical involvement of platelets in inflammatory processes like acute ischemic stroke, and viral infections like Coronavirus disease 2019 (COVID-19). This has encouraged the researchers to investigate the contribution of platelets in the pathology of various thrombo-inflammatory diseases. The inhibition of platelet surface receptors or their intracellular signaling which mediate initial platelet activation and adhesion might prove to be suitable targets in thrombo-inflammatory disorders. Thus, the present review summarizes the concept and mechanism of platelet signaling and briefly discuss their role in sterile and non-sterile thrombo-inflammation, with the emphasis on role of platelets in COVID-19 induced thrombo-inflammation. The aim of this review is to summarize the recent developments in deciphering the role of the platelets in thrombo-inflammation and discuss their potential as pharmaceutical targets.

Platelet-derived extracellular vesicles encapsulate microRNA-34c-5p to ameliorate inflammatory response of coronary artery endothelial cells via PODXL-mediated P38 MAPK signaling pathway

BACKGROUND AND AIMS

Low-grade chronic inflammation was reported to serve as a distinctive pathophysiologic feature of coronary artery disease (CAD), the leading cause of death around the world. Herein, the current study aimed to explore whether and how microRNA-34c-5p (miR-34c-5p), a miRNA enriched in extracellular vesicles (EVs) originated from the activated platelet (PLT-EVs), affects the inflammation of human coronary artery endothelial cells (HCAECs).

METHODS AND RESULTS

HCAECs were established as an in vitro cell model using oxidized low-density lipoprotein (ox-LDL). miR-34c-5p, an abundant miRNA in PLT-EVs, can be transferred to HCAECs and target PODXL by binding to its 3'UTR. Gain- and loss-of-function experiments of miR-34c-5p and podocalyxin (PODXL) were performed in ox-LDL-induced HCAECs. Subsequently, HCAECs were subjected to co-culture with PLT-EVs, followed by detection of the expression patterns of key pro-inflammatory factors. Either miR-34c-5p mimic or PLT-EVs harboring miR-34c-5p attenuated the ox-LDL-evoked inflammation in HCAECs by suppressing interleukin-1β (IL-1β), IL-6 and tumor necrosis factor-α (TNF-α). By blocking the P38 MAPK signaling pathway, miR-34c-5p-mediated depletion of PODXL contributed to protection against ox-LDL-induced inflammation. In vitro findings were further validated by findings observed in ApoE knock-out mice. Additionally, miR-34c-5p in PLT-EVs showed an athero-protective role in the murine model.

CONCLUSION

Altogether, our findings highlighted that miR-34c-5p in PLT-EVs could alleviate inflammation response in HCAECs by targeting PODXL and inactivation of the P38 MAPK signaling pathway.

miR-146a-5p, miR-223-3p and miR-142-3p as Potential Predictors of Major Adverse Cardiac Events in Young Patients with Acute ST Elevation Myocardial Infarction-Added Value over Left Ventricular Myocardial Work Indices

Acute ST elevation myocardial infarction (STEMI) remains a leading cause of morbidity and mortality worldwide despite continuous advances in diagnostic, prognostic and therapeutic methods. Myocardial work (MW) indices and miRNAs have both emerged as potential prognostic markers in acute coronary syndromes in recent years. In this study we aim to assess the prognostic role of myocardial work indices and of a group of miRNAs in young patients with STEMI. We enrolled 50 young patients (<55 years) with STEMI who underwent primary PCI and 10 healthy age-matched controls. We performed standard 2D and 3D echocardiography; we also calculated left ventricular global longitudinal strain (GLS) and the derived myocardial work indices. Using RT-PCR we determined the plasmatic levels of six miRNAs: miR-223-3p, miR-142-3p, miR-146a-5p, miR-125a-5p, miR-486-5p and miR-155-5p. We assessed the occurrence of major adverse cardiac events (MACE) at up to one year after STEMI. Out of 50 patients, 18% experienced MACE at the one-year follow-up. In a Cox univariate logistic regression analysis, myocardial work indices were all significantly associated with MACE. The ROC analysis showed that GWI, GCW and GWE as a group have a better predictive value for MACE than each separately (AUC 0.951, p = 0.000). Patients with higher miRNAs values at baseline (miR-223-3p, miR-142-3p and miR-146a-5p) appear to have a higher probability of developing adverse events at 12 months of follow-up. ROC curves outlined for each variable confirmed their good predictive value (AUC = 0.832, p = 0.002 for miR-223-3p; AUC = 0.732, p = 0.031 for miR-142-3p and AUC = 0.848, p = 0.001 for miR-146a-5p); the group of three miRNAs also proved to have a better predictive value for MACE together than separately (AUC = 0.862). Moreover, adding each of the miRNAs (miR-233, miR-142-3p and miR-146a-5p) or all together over the myocardial work indices in the regression models improved their prognostic value. In conclusion, both myocardial work indices (GWI, GCW and GWE) and three miRNAs (miR-223-3p, miR-142-3p and miR-146a-5p) have the potential to be used as prognostic markers for adverse events after acute myocardial infarction. The combination of miRNAs and MW indices (measured at baseline) rather than each separately has very good predictive value for MACE in young STEMI patients (C-statistic 0.977).