Significance of circulating microRNAs in diabetes mellitus type 2 and platelet reactivity: bioinformatic analysis and review.

In the light of growing global epidemic of type 2 diabetes mellitus (T2DM), significant efforts are made to discover next-generation biomarkers for early detection of the disease. Multiple mechanisms including inflammatory response, abnormal insulin secretion and glucose metabolism contribute to the development of T2DM. Platelet activation, on the other hand, is known to be one of the underlying mechanisms of atherosclerosis, which is a common T2DM complication that frequently results in ischemic events at later stages of the disease. Available data suggest that platelets contain large amounts of microRNAs (miRNAs) that are found in circulating body fluids, including the blood. Since miRNAs have been illustrated to play an important role in metabolic homeostasis through regulation of multiple genes, they attracted substantial scientific interest as diagnostic and prognostic biomarkers in T2DM. Various miRNAs, as well as their target genes are implicated in the complex pathophysiology of T2DM. This article will first review the different miRNAs studied in the context of T2DM and platelet reactivity, and subsequently present original results from bioinformatic analyses of published reports, identifying a common gene (PRKAR1A) linked to glucose metabolism, blood coagulation and insulin signalling and targeted by miRNAs in T2DM. Moreover, miRNA-target gene interaction networks built upon Gene Ontology information from electronic databases were developed. According to our results, miR-30a-5p, miR-30d-5p and miR-30c-5p are the most widely regulated miRNAs across all specified ontologies, hence they are the most promising biomarkers of T2DM to be investigated in future clinical studies.

Resistin is a prognostic factor for death in type 2 diabetes.

PURPOSE: To investigate the association of leptin, resistin, and tumour necrosis factor α (TNF-α) with prognosis in type 2 diabetes (T2D). METHODS: Analysis included 284 T2D patients. Apart from routine laboratory parameters, baseline leptin, resistin, and TNF-α concentrations were measured. Patients were followed for a median of 5.4 years. The primary endpoint was all-cause death at follow-up. The secondary endpoint was a composite of death, acute coronary syndrome, and stroke or transient ischemic attack. RESULTS: At baseline, median age was 68 years, and 48% of patients were female. Data on the primary endpoint were obtained for all patients: 32 (11%) died during follow-up. Data on the secondary endpoint were available for 230 patients, of whom 45 (20%) reached the secondary endpoint. In univariate analyses, older age, heart failure, lower-glomerular filtration rate, and higher resistin, TNF-α and NT-proBNP concentrations were predictors of the study endpoints. Of these variables, only resistin remained an independent predictor of both study endpoints in multivariate models. In receiver-operating characteristic analysis, area under the curve for resistin was 0.7. Resistin concentration of greater than or equal to 11.4 ng/mL had sensitivity of 41% and specificity of 91% for prediction of death at follow-up (Youden's index). CONCLUSIONS: Higher resistin is associated with reduced survival in T2D, irrespectively of TNF-α. Resistin concentration of above 11 ng/mL indicates T2D patients at an increased risk of unfavourable outcomes. Leptin was not a prognostic factor. These results suggest that in T2D, association of resistin with unfavourable outcomes might, at least in part, result from its pro-inflammatory properties.

Association of frequent genetic variants in platelet activation pathway genes with large-vessel ischemic stroke in Polish population.

Platelets are critically involved in the development of cerebral ischemia. Our study aimed to establish an association between frequent (minor allele frequency (MAF) > 5%) genetic polymorphisms in 84 candidate genetic loci previously linked to platelet reactivity by the use of next-generation sequencing of exons from pooled DNA samples in Polish patients with a history of large-vessel ischemic stroke. Genetic analysis was performed on blood samples obtained from 500 patients (diagnosed with acute non-cardioembolic ischemic stroke with coexisting large-artery atherosclerosis) and age/sex/history of smoking matching 500 controls of Polish origin with high risk of cardiovascular disease. Sequencing of 10 pools (five for each ischemic and control groups) was performed on the Ilumina HiSeq2500 sequencer which generated an average of 36.1 (22.7-45.9 range) million pair-end 101 bp reads and 5.3 (3-7 range) Gbp per pooled sample consisting of 100 subjects. In total, we observed 789 frequent polymorphisms in the sequenced 84 genes (703 of single-nucleotide polymorphism (SNP) type and 86 indels). When the MAF between control and stroke groups was compared, only two intronic polymorphisms (1 SNP and 1 indel) in RGS7 (rs127445 36) and ANKS1B (rs398098426) genes, respectively, show statistically significant differences, which persisted after individual genotyping of the variants and adjustment for potential confounding factors. From the remaining variants, 35 polymorphisms displayed various degrees of nominal significance (from 0.6.3 × 10-5 to 5 × 10-2) and 754 polymorphisms did not show any statistical significance when comparison was evaluated for differences in MAF between the study groups. In conclusion, the results of the study demonstrate statistically significant differences in two frequent intronic genetic variants (in RGS7 and ANKS1B) that could be associated with the platelet function between ischemic stroke patients with coexisting large-vessel atherosclerosis and control patients having high vascular risk.

Population-Specific Associations of Deleterious Rare Variants in Coding Region of P2RY1-P2RY12 Purinergic Receptor Genes in Large-Vessel Ischemic Stroke Patients.

The contribution of low-frequency and damaging genetic variants associated with platelet function to ischemic stroke (IS) susceptibility remains unknown. We employed a deep re-sequencing approach in Polish patients in order to investigate the contribution of rare variants (minor allele frequency, MAF < 1%) to the IS genetic susceptibility in this population. The genes selected for re-sequencing consisted of 26 genes coding for proteins associated with the surface membrane of platelets. Targeted pooled re-sequencing (Illumina HiSeq 2500) was performed on genomic DNA of 500 cases (patients with history of clinically proven diagnosis of large-vessel IS) and 500 controls. After quality control and prioritization based on allele frequency and damaging probability, follow-up individual genotyping of deleterious rare variants was performed in patients from the original cohort. Gene-based analyses identified an association between IS and 6 rare functional and damaging variants in the purinergic genes (P2RY1 and P2RY12 locus). The predicted properties of the most damaging rare variants in P2RY1 and P2RY12 were confirmed by using mouse fibroblast cell cultures transfected with plasmid constructs containing cDNA of mutated variants (FLIPR on FlexStation3). This study identified a putative role for rare variants in P2RY1 and P2RY12 genes involved in platelet reactivity on large-vessel IS susceptibility in a Polish population.

MiR-126 Is an Independent Predictor of Long-Term All-Cause Mortality in Patients with Type 2 Diabetes Mellitus.

MicroRNAs are endogenous non-coding RNAs that are involved in numerous biological processes through regulation of gene expression. The aim of our study was to determine the ability of several miRNAs to predict mortality and response to antiplatelet treatment among T2DM patients. Two hundred fifty-two patients with diabetes were enrolled in the study. Among the patients included, 26 (10.3%) patients died within a median observation time of 5.9 years. The patients were receiving either acetylsalicylic acid (ASA) 75 mg (65%), ASA 150 mg (15%) or clopidogrel (19%). Plasma miR-126, miR-223, miR-125a-3p and Let-7e expressions were assessed by quantitative real time PCR and compared between the patients who survived and those who died. Adjusted Cox-regression analysis was used for prediction of mortality. Differential miRNA expression due to different antiplatelet treatment was analyzed. After including all miRNAs into one multivariate Cox regression model, only miR-126 was predictive of future occurrence of long-term all-cause death (HR = 5.82, 95% CI: 1.3-24.9; p = 0.024). Furthermore, miR-126, Let-7e and miR-223 expressions in the clopidogrel group were significantly higher than in the ASA group (p = 0.014; p = 0.013; p = 0.028, respectively). To conclude, miR-126 expression is a strong and independent predictor of long-term all-cause mortality among patients with T2DM. Moreover, miR-223, miR-126 and Let-7e present significant interactions with antiplatelet treatment regimens and clinical outcomes.

The role of acetylsalicylic acid and circulating microRNAs in primary prevention of cardiovascular events in patients with Diabetes Mellitus Type 2 - A Review.

INTRODUCTION: Type 2 diabetes mellitus (T2DM) is a common metabolic disorder, which carries a risk for atherosclerosis and cardiovascular impairment. The purpose of this review is to demonstrate the role of acetylsalicylic acid (ASA) in primary cardiovascular prevention in T2DM patients, as well as present an outline of microRNAs (miRNA) relevant to ASA therapy and should be evaluated as targets to improve treatment. BRIEF DESCRIPTION OF STATE OF KNOWLEDGE: Although the etiology of hypercoagulable state in T2DM is considered multifactorial, attention mainly focuses on platelet disturbances. Platelets in T2DM not only demonstrate intensified adhesion, activation, aggregation, and thrombin generation, but are likely to deliver miRNAs at specific sites of action in the cardiovascular system, hence contributing to the pathogenesis of cardiovascular events. OBJECTIVE: Since cardiovascular disease (CVD) is currently the leading cause of mortality among T2DM patients, appropriate risk stratification and management is necessary to reduce morbidity and mortality in this group. A large number of T2DM patients show inadequate response to antiplatelet therapy, which currently revolves around ASA, despite compliance with treatment regimens proposed by the guidelines. CONCLUSIONS: The review shows that the use of ASA for primary prevention is beneficial in patients at high cardiovascular risk. However, it is important to select patients in whom ASA therapy will bring the most beneficial outcome with minimal risk for adverse effects. This can be potentially achieved with the use of unique biomarkers. The biologically diverse characteristics of miRNA make them a promising novel biomarker and potential tool for better risk stratification, as well as antiplatelet therapy optimization.

Effectiveness of Antiplatelet Drugs Under Therapeutic Hypothermia: A Comprehensive Review.

Out-of-hospital cardiac arrest is among the most frequent causes of death worldwide. Immediate intervention, as well as dual antiplatelet therapy consisting of acetylsalicylic acid and a P2Y12 inhibitor is often recommended. In line with the growing number of reports on cardiac arrest treatment, therapeutic hypothermia (TH) has been proposed for unconscious patients to improve neurological outcomes. Nevertheless, studies report controversial and often discrepant results on the effect of hypothermia on blood coagulability and platelet reactivity. In this review, we summarize the knowledge on platelet function under diverse hypothermic conditions. Additionally, we review the current literature on the effect of systemic hypothermia on pharmacokinetic and pharmacodynamic properties of antiplatelet agents. It has been shown that TH can alter the effectiveness of antiplatelet agents, including P2Y12 inhibitors, through multiple mechanisms, hence, special attention should be paid while implementing antiplatelet therapy in patients under TH conditions.

Switching between P2Y12 antagonists - From bench to bedside.

Platelet P2Y12 receptors play a key role in platelet activation and thrombus formation. Accordingly, P2Y12 receptor antagonists are the cornerstone of secondary prevention of atherothrombotic events in patients undergoing percutaneous coronary intervention (PCI). The availability of different oral P2Y12 antagonists (clopidogrel, prasugrel, ticagrelor) along with the introduction of the first intravenous P2Y12 antagonist cangrelor offer an opportunity to individualize antiplatelet therapy according to the changing clinical setting. The recent International Expert Consensus provided the first recommendations on switching between the P2Y12 antagonists. While the consensus greatly helps to guide switching between P2Y12 antagonists, a number of controversial clinical scenarios remain where the evidence regarding the optimal switch strategy is scarce. In such clinical scenarios, understanding of the (i) pharmacological properties of P2Y12 antagonists, (ii) recent evidence from pharmacodynamics studies, clinical trials and registries, and (iii) factors affecting the efficacy and safety of the P2Y12 antagonists, all summarized below, are crucial to choose the optimal switch strategy.

Increased burden of rare deleterious variants of the KCNQ1 gene in patients with large­vessel ischemic stroke.

The impact of rare and damaging variants in genes associated with platelet function in large­vessel ischemic stroke (LVIS) remains unknown. The aim of this study was to investigate the contribution of some of these variants to the genetic susceptibility to LVIS in Polish patients using a deep re­sequencing of 54 selected genes, coding for proteins associated with altered platelet function. Targeted pooled re­sequencing (Illumina HiSeq 2500) was performed on genomic DNA of 500 cases (patients with history of clinically proven diagnosis of LVIS) and 500 age­, smoking status­, and sex­matched controls (no history of any type of stroke), and from the same population as patients with LVIS. After quality control and prioritization based on allele frequency and damaging probability, individual genotyping of all deleterious rare variants was performed in patients from the original cohort, and stratified to concomitant cardiac conditions differing between the study and stroke groups. We demonstrated a statistically significant increase in the number of rare and potentially damaging variants in some of the investigated genes in the LVIS pool (an increase in the genomic variants burden). Furthermore, we identified an association between LVIS and 6 rare functional and damaging variants in the Kv7.1 potassium channel gene (KCNQ1). The predicted functional properties (partial loss­of function) for the three most damaging variants in KCNQ1 coding locus were further confirmed in vitro by analyzing the membrane potential changes in cell lines co­transfected heterogeneously with human muscarinic type 1 receptor and wild­type or mutated KCNQ1 cDNA constructs using fluorescence imaging plate reader. The study demonstrated an increased rare variants burden for 54 genes associated with platelet function, and identified a putative role for rare damaging variants in the KCNQ1 gene on LVIS susceptibility in the Polish population.

The Potential Role of Platelet-Related microRNAs in the Development of Cardiovascular Events in High-Risk Populations, Including Diabetic Patients: A Review.

Platelet activation plays a pivotal role in the development and progression of atherosclerosis, which often leads to potentially fatal ischemic events at later stages of the disease. Platelets and platelet microvesicles (PMVs) contain large amounts of microRNA (miRNA), which contributes largely to the pool of circulating miRNAs. Hence, they represent a promising option for the development of innovative diagnostic biomarkers, that can be specific for the underlying etiology. Circulating miRNAs can be responsible for intracellular communication and may have a biological effect on target cells. As miRNAs associated to both cardiovascular diseases (CVD) and diabetes mellitus can be measured by means of a wide array of techniques, they can be exploited as an innovative class of smart disease biomarkers. In this manuscript, we provide an outline of miRNAs associated with platelet function and reactivity (miR-223, miR-126, miR-197, miR-191, miR-21, miR-150, miR-155, miR-140, miR-96, miR-98) that should be evaluated as novel biomarkers to improve diagnostics and treatment of CVD.

New single-nucleotide polymorphisms associated with differences in platelet reactivity and their influence on survival in patients with type 2 diabetes treated with acetylsalicylic acid: an observational study.

AIMS: Genetic polymorphisms may contribute to platelet reactivity in diabetic patients; however, the information on their influence on long-term antiplatelet therapy is lacking. Our aim was to evaluate the role of previously described genetic variants and platelet reactivity on risk of all-cause mortality and cardiovascular events. METHODS: Blood samples were obtained from 303 Caucasian patients. Genome-wide genotyping was performed using Illumina Human Omni 2.5-Quad microarrays, and individual genotyping of selected SNPs was performed using a custom Sequenom iPLEX assay in conjunction with the Mass ARRAY platform. Platelet reactivity was measured with VerifyNow Aspirin Assay and PFA-100 Assay. Univariate and multivariate Cox regression analyses were performed to determine the impact of genetic variants and platelets reactivity on risk of all-cause mortality and cardiovascular events. RESULTS: Among the 237 patients included in the follow-up, death from any cause occurred in 34 (14.3%) patients and cardiovascular events occurred in 51 (21.5%) patients within a median observation time of 71 months (5.9 years). In univariate analyses, significant association in the presence of minor alleles in TXBA2R (rs1131882) with primary (HR 2.54, 95% CI 1.15-5.60, p = 0.021) and secondary endpoint (HR 2.06, 95% CI 1.06-4.04, p = 0.034) was observed. In addition, multivariate analyses revealed the impact of this polymorphism on primary (HR 2.34, 95% CI 1.09-5.00, p = 0.029) and secondary endpoint (HR 1.89, 95% CI 1.00-3.57, p = 0.048). CONCLUSIONS: Results of the study demonstrate for the first time an association between genetic polymorphism within TXBA2R gene encoding platelet's surface receptor and long-term survival of diabetic patients treated with ASA.

Common genetic variants in platelet surface receptors and its association with ischemic stroke.

Ischemic stroke has been named one of the leading causes of death worldwide. Whereas numerous biological mechanisms and molecules were found to be associated with stroke, platelets are particularly contributive to its pathogenesis. Recent data indicate considerable variability in platelet phenotype which accounts for differences in platelet surface receptor function, count and reactivity. These features collectively influence both the events leading to a disease and effectiveness of antiplatelet therapies. Consequently, genetic variants predisposing to cerebrovascular diseases can be sequenced using a wide array of techniques and become a useful tool in clinical setting. In this review, we provide an outline of common platelet polymorphisms that impose risk on ischemic stroke development and should be evaluated as targets to improve treatment. As study results are often inconsistent, partly due to differences in demographic characteristics between study populations and the fact that the functional impact of these variants has been relatively small, we conclude that both rare, low-frequency and common variants might account for genetic contribution on abnormal platelet response to antiplatelet drugs.