Platelet pathophysiology, pharmacology, and function in coronary artery disease

Inhibitory effects of resveratrol on platelet activation and thrombosis in colon cancer through regulation of the MAPK and cGMP/VASP pathways

Thrombosis is the primary cause of death in patients with cancer. Resveratrol inhibits platelet activation, a crucial pathophysiological basis of thrombosis, in healthy individuals. However, its effects and mechanisms of action in patients with colon cancer remain unknown. Here, we investigated the effect of resveratrol on platelet adhesion and aggregation in patients with colon cancer. Through numerous in vitro and in vivo analyses, including flow cytometry, western blotting, ELISA, and immunofluorescence and colon cancer rat models, we demonstrated that resveratrol reduced thrombosis in patients with colon cancer by inhibiting the phosphorylation of the MAPK and activating the cyclic-GMP/vasodilator-stimulated phosphoprotein pathway. These findings demonstrate the potential of resveratrol in reducing thrombosis in patients with colon cancer and could be used to develop novel therapeutic strategies for this condition.

Platelet count as a prognostic marker for acute respiratory distress syndrome

BACKGROUND

This study aimed to evaluate the role of platelet count (PLT) in the prognosis of patients with acute respiratory distress syndrome (ARDS).

METHODS

The data were extracted from the Medical Information Mart for Intensive Care database (version 2.2). Patients diagnosed with ARDS according to criteria from Berlin Definition and had the platelet count (PLT) measured within the first day after intensive care unit admission were analyzed. Based on PLT, ARDS patients were divided into four groups: PLT ≤ 100 × 109/L, PLT 101-200 × 109/L, PLT 201-300 × 109/L, and PLT > 300 × 109/L. The primary outcome was 28-day mortality. Survival probabilities were analyzed using Kaplan-Meier. Furthermore, the association between PLT and mortality in ARDS patients was assessed using a univariate and multivariable Cox proportional hazards model.

RESULTS

Overall, the final analysis included 3,207 eligible participants with ARDS. According to the Kaplan-Meier curves for 28-day mortality of PLT, PLT ≤ 100 × 109/L was associated with a higher incidence of mortality (P = 0.001), the same trends were observed in the 60-day (P = 0.001) and 90-day mortality (P = 0.001). In the multivariate model adjusted for the potential factors, the adjusted hazard ratio at PLT 101-200 × 109/L group, PLT 201-300 × 109/L, and PLT > 300 × 109/L was 0.681 [95% confidence interval (CI): 0.576-0.805, P < 0.001], 0.733 (95% CI: 0.604-0.889, P = 0.002), and 0.787 (95% CI: 0.624-0.994, P = 0.044) compared to the reference group (PLT ≤ 100 × 109/L), respectively. Similar relationships between the PLT ≤ 100 × 109/L group and 28-day mortality were obtained in most subgroups.

CONCLUSION

PLT appeared to be an independent predictor of mortality in critically ill patients with ARDS.

Pharmacogenomic Polygenic Model of Clopidogrel Predicts Recurrent Ischemic Events in Chinese Patients With Coronary Artery Disease

PURPOSE

Patients with coronary artery disease (CAD) need to take antiplatelet drugs regularly in order to prevent thrombosis; however, there is existing inter-individual variability in drug response. Pharmacogenomic studies indicate that drug response may also be influenced by genetic variants, and multiple genetic variants may work together. We assumed that patients carrying more risk alleles might have a worse clopidogrel drug response and that a polygenic model integrated different single variants might have the potential to explain clopidogrel drug response variability better. We aimed to investigate whether the polygenic model could be used to predict clopidogrel drug response.

METHODS

A total of 935 CAD patients were enrolled in the study. We investigated the association between 19 clopidogrel-related single-nucleotide polymorphisms (SNPs) and the incidence of recurrent ischemic events. Additionally, a polygenic model was constructed to assess the risk of ischemic events.

FINDINGS

There were only 2 SNPs of CYP2C8 gene (rs1934980 and rs17110453) that were nominally associated with incidence of recurrent ischemic events. We constructed a polygenic model integrated with 6 clopidogrel-related SNPs. When compared with patients carrying 6 or fewer risk alleles, patients with 7 or more risk alleles had a higher risk of ischemic events (hazard ratio = 1.87; P = 0.04).

IMPLICATIONS

The polygenetic model may be useful for clopidogrel drug response prediction in patients with CAD.

Antiplatelet drugs do not protect from platelet-leukocyte aggregation in coronary artery disease

BACKGROUND

Despite advances in cardiovascular medicine, coronary artery disease (CAD) remains a leading cause of mortality. Among the pathophysiological features of this condition, platelet-leukocyte aggregates (PLAs) require further attention, either as diagnostic/prognostic disease markers or as potential interventional targets.

OBJECTIVES

In this study, we characterized PLAs in patients with CAD. Primarily, we investigated the association of PLA levels with CAD diagnosis. In addition, the basal levels of platelet activation and degranulation were assessed in patients with CAD and controls, and their correlation with PLA levels was analyzed. Finally, the effect of antiplatelet treatments on circulating PLA numbers, basal platelet activation, and degranulation was studied in patients with CAD.

METHODS

Participants were recruited at the Department of Cardiology of the University Heart and Vascular Centre Hamburg Eppendorf. Among patients admitted with severe chest pain, the diagnosis of CAD was made angiographically, and patients without CAD were used as controls. PLAs, platelet activation, and platelet degranulation were assessed by flow cytometry.

RESULTS

Circulating PLAs and basal platelet degranulation levels were significantly higher in patients with CAD than in controls. Surprisingly, there was no significant correlation between PLA levels and platelet degranulation (or any other measured parameter). In addition, patients with CAD on antiplatelet therapy did not display lower PLA or platelet degranulation levels compared with those in controls.

CONCLUSION

Overall, these data suggest a mechanism of PLA formation that is independent of platelet activation or degranulation and highlights the inefficiency of current antiplatelet treatments for the prevention of basal platelet degranulation and PLA formation.

Hemoglobin albumin lymphocyte and platelet score and all-cause mortality in coronary heart disease: a retrospective cohort study of NHANES database

Aim

Anemia, inflammatory status, and malnutrition are all important factors in the prognosis of cardiovascular disease (CVD), and their interactions are also noteworthy. A recent scoring system, the hemoglobin albumin lymphocyte and platelet (HALP) score, combining multi-dimensional metrics, has been used in the prognoses of many diseases except coronary heart disease (CHD). Herein, this study aims to explore the association between HALP score and all-cause mortality in patients with CHD.

Methods

Demographic and clinical data of adult patients with CHD were extracted from the National Health and Nutrition Examination Surveys (NHANES) database from 2003 to 2018 in this retrospective cohort study. Weighted univariate and multivariate COX proportional hazard models were used for covariates screening and exploration of the association between HALP score and all-cause mortality. The evaluation indexes were hazard ratios (ORs) and 95% confidence intervals (CIs). Kaplan-Meier (KM) curve and the receiver operator characteristic (ROC) curve were used to assess the predictive performance of HALP on CHD prognosis. In addition, subgroup analyses of age and congestive heart failure (CHF) were also performed.

Results

Among the eligible patients, 657 died of all-cause mortality. After adjusting for the covariates including age, education level, PIR, marital status, smoking, physical activity, total energy intake, CHF, stroke, hypertension, DM, CKD, cancer or malignancy, monocyte, drug for CVD, treatment for anemia, anticoagulants drug, and adrenal cortical steroids, we found that HALP score was negatively associated with the risk of all-cause mortality [HR = 0.83, 95% CI: (0.74-0.93)]. Compared with patients with high HALP scores, those who had lower HALP scores seemed to have a higher risk of all-cause mortality (all P < 0.05). HALP score has a potential predictive value on CHD prognosis with an area under the curve (AUC) of 0.61. Furthermore, in patients aged <65 years, with or without CHF, a lower HALP score was also associated with a higher risk of all-cause mortality (all P < 0.05).

Conclusions

HALP score has a potential predictive value on CHD prognosis; however, the causal association between HALP score and mortality in patients with CHD needs further exploration.

Platelet Glycoprotein-Ib (GPIb) May Serve as a Bridge between Type 2 Diabetes Mellitus (T2DM) and Atherosclerosis, Making It a Potential Target for Antiplatelet Agents in T2DM Patients

Type 2 diabetes mellitus (T2DM) is a persistent metabolic condition that contributes to the development of cardiovascular diseases. Numerous studies have provided evidence that individuals with T2DM are at a greater risk of developing cardiovascular diseases, typically two to four times more likely than those without T2DM, mainly due to an increased risk of atherosclerosis. The rupture of an atherosclerotic plaque leading to pathological thrombosis is commonly recognized as a significant factor in advancing cardiovascular diseases caused by TD2M, with platelets inducing the impact of plaque rupture in established atherosclerosis and predisposing to the primary expansion of atherosclerosis. Studies suggest that individuals with T2DM have platelets that display higher baseline activation and reactivity than those without the condition. The expression enhancement of several platelet receptors is known to regulate platelet activation signaling, including platelet glycoprotein-Ib (GPIb). Furthermore, the high expression of platelet GP1b has been reported to increase the risk of platelet adhesion, platelet-leucocyte interaction, and thrombo-inflammatory pathology. However, the study exploring the role of GP1b in promoting platelet activation-induced cardiovascular diseases in T2DM patients is still limited. Therefore, we summarize the important findings regarding pathophysiological continuity between T2DM, platelet GPIb, and atherosclerosis and highlight the potential therapy targeting GPIb as a novel antiplatelet agent for preventing further cardiovascular incidents in TD2M patients.

Mean platelet volume modifies the contribution of homocysteine to cardiovascular disease: A real-world study

BACKGROUND AND AIMS

The effect of reductions in homocysteine (Hcy) on cardiovascular disease (CVD) was suggested to be modified by platelet activation, but the interaction between Hcy and platelet activation on CVD events is not well studied. Here, we aimed to examine the interaction between Hcy and platelet activation on CVD in a large, real-world population.

METHODS AND RESULTS

A total of 27,234 patients with hypertension (mean 63 years, 48% male) who were registered in Taicang city and free of CVD were prospectively followed up for new CVD events from 2017 to 2020. Hcy and platelet indices including mean platelet volume (MPV) were assayed at baseline. A total of 1063 CVD events were recorded during follow-up. Hcy at baseline was significantly associated with a higher risk of CVD (HR = 1.85, P < 0.001 for log-transformed Hcy). MPV showed a significant interaction effect with Hcy on CVD (HR = 1.20, P = 0.030 for the interaction term). The association between Hcy and CVD was significantly stronger in participants with a large (vs. small) MPV (HR = 2.71 vs. 1.32, P = 0.029 for log-transformed Hcy). For participants with both elevated Hcy and a large MPV, the attributable proportion of CVD events due to their interaction was 0.26 (95% CI: 0.06-0.45).

CONCLUSIONS

The association between Hcy and CVD was significantly stronger in patients with hypertension with a larger MPV. MPV may modify the contribution of Hcy to CVD events through synergistic interactions with Hcy. These findings suggest that MPV could be monitored and controlled in the prevention of CVD.

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.

Prognostic value of the PDW/HDL-C ratio in patients with chest pain symptoms and coronary artery calcification

Background

Platelet-related parameters and HDL-C have been regarded as reliable and alternative markers of coronary heart disease (CHD) and the independent predictors of cardiovascular outcomes. PDW is a simple platelet index, which increases during platelet activation. Whether the PDW/HDL-C ratio predicts major adverse cardiovascular and cerebrovascular events (MACCEs) in patients who complained of chest pain and confirmed coronary artery calcification remains to be investigated. This study aimed to investigate the prognostic value of the PDW/HDL-C ratio in patients with chest pain symptoms and coronary artery calcification.

Methods

A total of 5,647 patients with chest pain who underwent coronary computer tomography angiography (CTA) were enrolled in this study. Patients were divided into two groups according to their PDW/HDL-C ratio or whether the MACCE occurs. The primary outcomes were new-onset MACCEs, defined as the composite of all-cause death, non-fatal MI, non-fatal stroke, revascularization, malignant arrhythmia, and severe heart failure.

Results

All patients had varying degrees of coronary calcification, with a mean CACS of 97.60 (22.60, 942.75), and the level of CACS in the MACCEs group was significantly higher than that in non-MACCE (P<0.001). During the 89-month follow-up, 304 (5.38%) MACCEs were recorded. The incidence of MACCEs was significantly higher in patients with the PDW/HDL-C ratio > 13.33. The K–M survival curves showed that patients in the high PDW/HDL-C ratio group had significantly lower survival rates than patients in the low PDW/HDL-C ratio group (log-rank test: P < 0.001). Multivariate Cox hazard regression analysis reveals that the PDW/HDL ratio was an independent predictor of MACCEs (HR: 1.604, 95% CI: 1.263–2.035; P < 0.001). Cox regression analysis showed that participants with a lower PDW/HDL-C ratio had a higher risk of MACCEs than those in the higher ratio group. The incidence of MACCEs was also more common in the PDW/HDL-C ratio > 13.33 group among different severities of coronary artery calcification. Furthermore, adding the PDW/HDL-C ratio to the traditional prognostic model for MACCEs improved C-statistic (P < 0.001), the NRI value (11.3% improvement, 95% CI: 0.018–0.196, P = 0.01), and the IDI value (0.7% improvement, 95% CI: 0.003–0.010, P < 0.001).

Conclusion

The higher PDW/HDL-C ratio was independently associated with the increasing risk of MACCEs in patients with chest pain symptoms and coronary artery calcification. In patients with moderate calcification, mild coronary artery stenosis, and CAD verified by CTA, the incidence of MACCEs increased significantly in the PDW/HDL-C ratio > 13.33 group. Adding the PDW/HDL-C ratio to the traditional model provided had an incremental prognostic value for MACCEs.

Contribution of CYP19A1, CYP1A1, and CYP1A2 polymorphisms in coronary heart disease risk among the Chinese Han population

The previous study has pointed to that endogenous CYP metabolites play an important role in the pathogenesis of coronary heart disease (CHD). The study aimed to identify the association of CYP19A1, CYP1A1, and CYP1A2 polymorphisms with CHD susceptibility in a Chinese Han population. A total of 960 genetically unrelated participants consist of 480 CHD patients and 480 healthy controls were enrolled. Nine SNPs in CYP19A1, CYP1A1, and CYP1A2 were randomly selected and genotyped using the Agena MassARRAY platform. Logistic regression analysis was used for the relationship between selected SNPs and CHD susceptibility by calculating odds ratios (OR) with 95% confidence intervals (CI) adjusted for age and gender. The distribution of clinical characteristics in different genotypes was evaluated by one-way analysis of variance (ANOVA). CYP1A2 rs2470890 TT genotype had a higher CHD risk compared with CC genotype (OR = 3.06, p = 0.032) or CC-CT genotype (OR = 3.04, p = 0.033). Moreover, the contribution of CYP19A1 and CYP1A2 polymorphisms to CHD susceptibility was associated with age, gender, and clinical phenotypes (course of the disease and Gensini score). Besides, CYP1A2 rs762551 was related to serum levels of red blood cell, triglyceride, total cholesterol, and low-density lipoprotein cholesterol (LDL-C, p < 0.05). Our findings provided scientific evidence about CYP19A1, CYP1A1, and CYP1A2 polymorphisms on CHD incidence.

Targeting Platelet Activation in Abdominal Aortic Aneurysm: Current Knowledge and Perspectives

Abdominal aortic aneurysm (AAA) is a potentially fatal vascular disease that involves complex multifactorial hemodynamic, thrombotic, inflammatory, and aortic wall remodeling processes. However, its mechanisms are incompletely understood. It has become increasingly clear that platelets are involved in pathological processes of vascular diseases beyond their role in hemostasis and thrombosis. Platelet activation with membrane receptors and secreted mediators promotes thrombus formation and the accumulation of inflammatory cells, which may play an important role in the development of AAA by destroying the structural integrity and stability of the vessel wall. Turbulent blood flow in aortic aneurysms promotes platelet activation and aggregation. Platelet count and heterogeneity are important predictive, diagnostic, and prognostic indicators of AAA. We summarize the relationship between platelet activation and AAA development and propose future research directions and possible clinical applications.

Is platelet responsiveness to clopidogrel attenuated in overweight or obese patients and why? A reverse translational study in mice

BACKGROUND AND PURPOSE

Overweight or obese patients exhibit poorer platelet responses to clopidogrel. However, the mechanisms behind this phenotype remain to be elucidated. Here, we sought to discover whether and why obesity could affect the metabolic activation of and/or platelet response to clopidogrel in obese patients and high-fat diet-induced obese mice.

EXPERIMENTAL APPROACH

A post hoc stratified analysis of an observational clinical study was performed to investigate changes in residual platelet reactivity with increasing body weight in patients taking clopidogrel. Furthermore, high-fat diet-induced obese mice were used to reveal alterations in systemic exposure of clopidogrel thiol active metabolite H4, ADP-induced platelet activation and aggregation, the expression of genes involved in the metabolic activation of clopidogrel, count of circulating reticulated and mature platelets, and proliferation profiles of megakaryocytes in bone marrow. The relevant genes and potential signalling pathways were predicted and enriched according to the GEO datasets available from obese patients.

KEY RESULTS

Obese patients exhibited significantly attenuated antiplatelet effects of clopidogrel. In diet-induced obese mice, systemic exposure of clopidogrel active metabolite H4 was reduced but that of its hydrolytic metabolite was increased due to down-regulation of certain P450s but up-regulation of carboxylesterase-1 in the liver. Moreover, enhanced proliferation of megakaryocytes and elevated platelet count also contributed.

CONCLUSION AND IMPLICATIONS

Obesity attenuated metabolic activation of clopidogrel and increased counts of circulating reticulated and mature platelets, leading to impaired platelet responsiveness to the drug in mice, suggesting that clopidogrel dosage may need to be adjusted adequately in overweight or obese patients.

Platelet Activation and Plasma Levels of Furin Are Associated With Prognosis of Patients With Coronary Artery Disease and COVID-19

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Prognostic value of peripheral blood inflammatory cell subsets in patients with acute coronary syndrome undergoing percutaneous coronary intervention

Objective

This study aimed to investigate the predictive value of inflammatory cells in peripheral blood on the prognosis of patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI).

Methods

Patients (n=1558) were consecutively enrolled and the median follow-up was 1142 days. Patients were divided into the major adverse cardiac events (MACE) 1 group (n=63) (all-cause mortality [n=58] and rehospitalization for severe heart failure [n=5], no MACE1 group (n=1495), MACE2 group (n=38) (cardiac mortality [n=33] and rehospitalization for severe heart failure [n=5]), and no MACE2 group (n=1520). The neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR), and platelet-to-lymphocyte ratio (PLR) were analyzed.

Results

The NLR, MLR, and PLR were higher in the MACE groups than in the no MACE groups. Different subsets of inflammatory cells had similar diagnostic values for MACE. Kaplan–Meier curves showed that the survival time gradually decreased with an increase in the degree of risk as determined by the NLR, MLR, and PLR. The risk of MACE was highest in the extremely high-risk group.

Conclusion

Peripheral blood inflammatory cell subsets can predict MACE in patients with ACS undergoing PCI. These cell subsets could be important laboratory markers for the prognosis and clinical treatment of these patients.

Platelet bound complement split product (PC4d) is a marker of platelet activation and arterial vascular events in Systemic Lupus Erythematosus

Platelet-bound complement activation products (PC4d) are associated with thrombosis in Systemic Lupus Erythematosus (SLE). This study investigated the effect of PC4d on platelet function, as a mechanistic link to arterial thrombosis. In a cohort of 150 SLE patients, 13 events had occurred within five years of enrollment. Patients with arterial events had higher PC4d levels (13.6 [4.4-24.0] vs. 4.0 [2.5-8.3] net MFI), with PC4d 10 being the optimal cutoff for event detection. The association of arterial events with PC4d remained significant after adjusting for antiphospholipid status, smoking, and prednisone use (p = 0.045). PC4d levels correlated with lower platelet counts (r = -0.26, p = 0.002), larger platelet volumes (r = 0.22, p = 0.009) and increased platelet aggregation: the adenosine diphosphate (ADP) concentration to achieve 50% maximal aggregation (EC₅₀) was lower in patients with PC4d 10 compared with PC4d < 10 (1.6 vs. 3.7, p = 0.038, respectively). These results suggest that PC4d may be a mechanistic marker for vascular disease in SLE.

Src-family Protein Tyrosine Kinases: A promising target for treating Cardiovascular Diseases

The Src-family protein tyrosine kinases (SFKs), a subfamily of non-receptor tyrosine kinases, are ubiquitously expressed in various cell types. Numerous studies have suggested that SFKs are related to signal transduction in major cardiac physiological and pathological processes, it is the activity of SFKs that is connected with the maintenance of cardiovascular homeostasis. Upon stimulation of various injury factors or stress, the phosphorylation state of SFKs is changed, which has been found to modulate different cardiac pathological conditions, such as hypertension, coronary heart disease, ischemic heart disease, myocardial ischemia-reperfusion injury, arrhythmia and cardiomyopathy via regulating cell growth, differentiation, movement and function, electrophysiologic signals. This review summarizes the basic information about SFKs, updates its role in the different processes underlying the development of multiple cardiovascular diseases (CVDs), and highlights their potential role as disease biomarkers and therapeutic targets, which would help understand the pathophysiology of CVDs and promote the further potential clinical adhibition.

Targeting Platelet in Atherosclerosis Plaque Formation: Current Knowledge and Future Perspectives

Besides their role in hemostasis and thrombosis, it has become increasingly clear that platelets are also involved in many other pathological processes of the vascular system, such as atherosclerotic plaque formation. Atherosclerosis is a chronic vascular inflammatory disease, which preferentially develops at sites under disturbed blood flow with low speeds and chaotic directions. Hyperglycemia, hyperlipidemia, and hypertension are all risk factors for atherosclerosis. When the vascular microenvironment changes, platelets can respond quickly to interact with endothelial cells and leukocytes, participating in atherosclerosis. This review discusses the important roles of platelets in the plaque formation under pro-atherogenic factors. Specifically, we discussed the platelet behaviors under disturbed flow, hyperglycemia, and hyperlipidemia conditions. We also summarized the molecular mechanisms involved in vascular inflammation during atherogenesis based on platelet receptors and secretion of inflammatory factors. Finally, we highlighted the studies of platelet migration in atherogenesis. In general, we elaborated an atherogenic role of platelets and the aspects that should be further studied in the future.

Integrative Genomic Analysis Reveals Four Protein Biomarkers for Platelet Traits

RATIONALE

Mean platelet volume (MPV) and platelet count (PLT) are platelet measures that have been linked to cardiovascular disease (CVD) and mortality risk. Identifying protein biomarkers for these measures may yield insights into CVD mechanisms.

OBJECTIVE

We aimed to identify causal protein biomarkers for MPV and PLT among 71 CVD-related plasma proteins measured in FHS (Framingham Heart Study) participants.

METHODS AND RESULTS

We conducted integrative analyses of genetic variants associated with PLT/MPV with protein quantitative trait locus variants associated with plasma proteins followed by Mendelian randomization to infer causal relations of proteins for PLT/MPV. We also tested protein-PLT/MPV association in FHS participants. Using induced pluripotent stem cell-derived megakaryocyte clones that produce functional platelets, we conducted RNA-sequencing and analyzed expression differences between low- and high-platelet producing clones. We then performed small interfering RNA gene knockdown experiments targeting genes encoding proteins with putatively causal platelet effects in megakaryocyte clones to examine effects on platelet production. In protein-trait association analyses, ten proteins were associated with MPV and 31 with PLT. Mendelian randomization identified 4 putatively causal proteins for MPV and 4 for PLT. GP-5 (Glycoprotein V), GRN (granulin), and MCAM (melanoma cell adhesion molecule) were associated with PLT, while MPO (myeloperoxidase) showed significant association with MPV in both analyses. RNA-sequencing analysis results were directionally concordant with observed and Mendelian randomization-inferred associations for GP-5, GRN, and MCAM. In siRNA gene knockdown experiments, silencing GP-5, GRN, and MPO decreased PLTs. Genome-wide association study results suggest several of these may be linked to CVD risk.

CONCLUSIONS

We identified 4 proteins that are causally linked to PLTs. These proteins may also have roles in the pathogenesis of CVD via a platelet/blood coagulation-based mechanism.

Mean platelet volume levels in children with sleep-disordered breathing: a meta-analysis

BACKGROUND

Pediatric sleep-disordered breathing (SDB) correlated with respiratory conditions of snoring and hypopnea. Mean platelet volume (MPV) was an inflammatory marker, related to increased inflammatory condition of pediatric patients. Increase of MPV level may cause failure to thrive or increased upper airway infection rate. The aim of this study was to perform systematic review and meta-analysis to investigate the difference on MPV values for pediatric SDB, and compare the change on MPV after surgery in patients with pediatric SDB.

METHODS

A systemic review of the studies from PubMed, EMBASE, and Cochrane Library databases was conducted in March 2020, supported by reviewing of published articles for studies comparing MPV in pediatric SDB. Meta-analysis was used to compare the change of MPV in pediatric SDB, and sub-group analysis was also used to compare the MPV decrease after surgeries of adenoidectomy or adenotonsillectomy.

RESULTS

There were seven studies included in the review. Six of them including 963 subjects showed that a significant increase of MPV was noted in pediatric SDB compared to those in pediatric non-SDB (P < 0.05). Total standardized mean difference (SMD) in MPV between pediatric SDB and non-SDB was 0.51 (95% CI =0.30-0.72, P < 0.05). A significant decrease of MPV was found in pediatric SDB patients who underwent surgery (total SMD = - 0.36; 95% CI = - 0.70- -0.02, P < 0.05). Decreases of MPV after adenoidectomy and adenotonsillectomy were observed, but only the effect of adenotonsillectomy had a statistical significance (total SMD = - 0.72; 95% CI = - 1.18 - -0.26, P < 0.05).

CONCLUSION

The MPV was significantly higher in patients with pediatric SDB, indicating the presence of increased platelet activity in pediatric SDB patients. The level of MPV could be reduced by the two surgeries, especially adenotonsillectomy.

Effects of 17β-Estradiol on the Plasminogen Activator System in Vascular Smooth Muscle Cells Treated with Lysophophatidylcholine

Objectives

When administered soon after menopause, hormone therapy can prevent coronary heart diseases in women. To explore the mechanism underlying the cardioprotective actions of estrogen, we investigated the effects of 17β-estradiol (17β-E₂) on the plasminogen activator system using cultured vascular smooth muscle cells (VSMCs).

Methods

VSMCs were isolated from rat aortas. Protein expression of plasminogen activator inhibitor type 1 (PAI-1) and tissue-type plasminogen activator (t-PA) were evaluated using Western blotting and enzyme-linked immunosorbent assay, respectively. The enzyme activity of PAI-1 in a conditioned medium was assessed via reverse fibrin overlay zymography and that of t-PA was assessed via fibrin overlay zymography. Gene expression was quantified using real-time reverse transcription-polymerase chain reaction.

Results

Following pre-treatment for 24 hours, 17β-E₂ suppressed both protein expression and enzyme activity of PAI-1 stimulated by lysophosphatidylcholine (lysoPC) in a significant and dose-dependent manner at a near physiological concentration. Moreover, 17β-E₂ (10⁻⁷ M) inhibited PAI-1 gene expression, and ICI 182,780—a specific estrogen receptor antagonist—blocked the effects of 17β-E₂ on the PAI-1 protein. 17β-E₂ did not affect t-PA secretion but significantly enhanced free t-PA activity through reduced binding to PAI-1. Furthermore, 17β-E₂ suppressed intracellular reactive oxygen species production and nuclear factor-κB-mediated transcription.

Conclusions

In VSMCs stimulated with lysoPC, 17β-E₂ reduced PAI-1 expression through a non-receptor-mediated mechanism via antioxidant activity as well as a receptor-mediated mechanism; however, it did not alter t-PA secretion. Of note, 17β-E₂ suppressed PAI-1 activity and concurrently enhanced t-PA activity, suggesting a beneficial influence on fibrinolysis.

Platelet activity and hypercoagulation in type 2 diabetes

Background

A strong correlation exists between type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD), with CVD and the presence of atherosclerosis being the prevailing cause of morbidity and mortality in diabetic populations. T2DM is accompanied by various coagulopathies, including anomalous clot formation or amyloid fibrin(ogen), the presence of dysregulated inflammatory molecules. Platelets are intimately involved in thrombus formation and particularly vulnerable to inflammatory cytokines.

Methods

The aim of this current study was therefore to assess whole blood (hyper)coagulability, platelet ultrastructure and receptor expression, as well as the levels of IL-1β, IL-6, IL-8 and sP-selectin in healthy and diabetic individuals. Platelet morphology was assessed through scanning electron microscopy (SEM), while assessment of GPIIb/IIIa receptor expression was performed with confocal microscopy and flow cytometry with the addition of FITC-PAC-1 and CD41-PE antibodies. IL-1β, IL-6 and IL-8 and sP-selectin levels were assessed using a multiplex assay.

Results

In T2DM there is significant upregulation of circulating inflammatory markers, hypercoagulation and platelet activation, with increased GPIIb/IIIa receptor expression, as seen with flow cytometry and confocal microscopy. Analyses showed that these receptors were additionally shed onto microparticles, which was confirmed with SEM.

Conclusions

Cumulatively, this provides mechanistic evidence that pathological states of platelets together with amyloid fibrin(ogen) in T2DM, might underpin an increased risk for cardiovascular events.