Inhibition Of Platelet Function Research Articles

The Impact of Marijuana Use on Postoperative Outcomes in Abdominal-based Free Flap Breast Reconstruction.

There is an increasing prevalence of marijuana use in the general population yet clinical studies on marijuana's effect on surgical outcomes remain limited. Marijuana's effect on wound healing, venous thromboembolism (VTE) due to endothelial inflammation, and bleeding due to inhibited platelet function have been cited based on animal models but have not been evaluated clinically in patients undergoing microsurgical reconstruction. Retrospective chart review was performed on all patients who underwent abdominal-based free flap breast reconstruction in a single institute from August 2018 to December 2022. Patient self-reported marijuana use, demographics, total narcotic use during hospitalization converted to oral morphine milligram equivalent (MME), and 90-day complications were collected and compared. A total of 162 patients were included and 13 patients (8.5%) had reported marijuana use on presurgical history. Marijuana users are more likely to be younger and report concurrent nicotine smoking. Marijuana users were also at a significantly elevated risk of developing symptomatic VTE (15 vs. 1%; odds ratio (OR) 13.4 [95% confidence interval (CI) 1.71-104.2]; p = 0.01) and marijuana use remained a significant risk factor with multivariate analysis. On postoperative 90-day complications, there was no increased risk of flap loss, reoperation, postoperative transfusion, or hematoma associated with marijuana use, and no significantly increased risk for overall donor or recipient site complications. Marijuana users required significantly more narcotics for pain control during hospitalization (100 ± 77 vs. 49 ± 45 MME; p = 0.0003), although they had similar lengths of stay, achievement of mobilization on post operative day (POD)1, and maximal pain scores. Marijuana use increases the risks of postoperative VTE and increased postoperative narcotic requirements in patients who underwent abdominal-based free flap breast reconstruction. Future prospective cohort study is required to further understand marijuana-associated risks in microsurgical procedures.

Impact of Platelet Hyperreactivity and Diabetes Mellitus on Ischemic Stroke Recurrence: A Single-Center Cohort Clinical Study.

Ischemic stroke recurrence (ISR) is prevented by inhibiting platelet function. To investigate the impact of high on-treatment platelet reactivity (HTPR) assessed by thromboelastography (TEG) and its risk factors on ISR in individuals who have experienced acute ischemic stroke (AIS) receiving dual anti-platelet therapy (DAPT). At the end of follow-up, a total of 264 patients who met the criteria were enrolled in this cohort study. The primary endpoint event was a recurrence of ischemic stroke within 90 days of onset. The ISR rate was 7.2% (19/264). The recurrence rate in the HTPR group was 15.1% (8/53), which was significantly higher than the 5.2% (11/211) in the non-HTPR group (p = 0.013), and the type 2 diabetes mellitus (T2DM) group (12.5%, 10/80) was also significantly higher compared to the non-T2DM group (4.9%, 9/184) (p = 0.028). T2DM was an isolated risk factor for HTPR (adjusted OR = 3.06, 95% CI 1.57-5.98, P = 0.001). Kaplan-Meier plots showed that the cumulative risk (CR) of ISR was statistically different in the HTPR and T2DM groups compared to the non-HTPR group (log-rank P = 0.009) and the non-T2DM group (log-rank P = 0.026), respectively. The HTPR and T2DM groups had greater hazard ratios (HR) of ISR than the non-HTPR (adjusted HR = 2.78, 95% CI 1.06-7.32, P = 0.038) and non-T2DM (adjusted HR = 2.64, 95% CI 1.01-6.92, P = 0.049) groups. Both HTPR and T2DM are linked to ISR. Platelet Inhibition Rate (PIR) of TEG can early identify patients who are at high risk for having another ischemic stroke in patients undergoing DAPT, and this study may offer more evidence in favor of clinically personalized treatment and secondary prevention tactics.

Enzyme-Induced Shape-Shifting Peptide Nanocarrier Coloaded with Paclitaxel and Dipyridamole Inhibits Platelet Function and Tumor Metastasis.

Tumor-associated platelets can bind to tumor cells and protect circulating tumor cells from NK-mediated immune surveillance. Tumor-associated platelets secrete cytokines to induce the epithelial-mesenchymal transition (EMT) in tumor cells, which promotes tumor metastasis. Combining chemotherapeutic agents with antiplatelet drugs can reduce the occurrence of metastasis, but the systemic application of chemotherapeutic agents and antiplatelet drugs is prone to causing serious side effects. Therefore, delivering drugs to the tumor microthrombus site for long-lasting inhibition is a problem that needs to be addressed. Here, we show that small molecule peptide nanoparticles containing the Cys-Arg-Glu-Lys-Ala (CREKA) peptide can deliver the platelet inhibitor dipyridamole (DIP) and the chemotherapeutic drug paclitaxel (PTX) to tumor tissues, thereby inhibiting tumor-associated platelet function while killing tumor cells. The drug-loaded nanoparticles PD/Pep1 inhibited platelet-tumor cell interactions, were effectively taken up by tumor cells, and underwent morphological transformation induced by alkaline phosphatase (ALP) to prolong the retention time of the drugs. After intravenous injection, PD/Pep1 can target tumors and inhibit tumor metastasis. Thus, this small molecule peptide nanoformulation provides a simple strategy for efficient drug delivery and shows promise as a novel cancer therapy platform.

Flow cytometry for comprehensive assessment of platelet functional activity in response to ADP stimulation.

Flow cytometry with adenosine diphosphate (ADP) allows to characterize molecular changes of platelet function caused by this physiologically important activation, but the methodology has not been thoroughly investigated, standardized and characterized yet. We analyzed the influence of several major variables and chose optimal conditions for platelet function assessment. For activation, 2.5 μM CaCl2 , 5 μM ADP and antibodies were added to diluted blood and incubated for 15 min. We analyzed kinetics of antibody binding and effects of their addition sequence, agonist concentration, blood dilution, exogenous calcium addition and platelet fixation. We tested our protocol on 11 healthy children, 22 healthy adult volunteers, 9 patients after a month on dual antiplatelet therapy after percutaneous coronary intervention (PCI), 7 adult patients and 14 children with immune thrombocytopenia (ITP). We found that our protocol is highly sensitive to ADP stimulation with low percentage of aggregates formation. The assay is also sensitive to platelet function inhibition in post-PCI patients. Finally, platelet preactivation with ITP plasma was stronger and caused increase in activation response to ADP stimulation compared to preactivation with low dose of ADP. Our assay is sensitive to antiplatelet therapy and platelet preactivation in ITP patients under physiological conditions with minimal percentage of aggregates formation.

Celastrol inhibits platelet function and thrombus formation

IntroductionCelastrol is an active pentacyclic triterpenoid extracted from Tripterygium wilfordii and has anti-inflammatory and anti-tumor properties. Whether Celastrol modulates platelet function remains unknown. Our study investigated its role in platelet function and thrombosis. MethodsHuman platelets were isolated and incubated with Celastrol (0, 1, 3 and 5 μM) at 37 °C for 1 h to measure platelet aggregation, granules release, spreading, thrombin-induced clot retraction and intracellular calcium mobilization. Additionally, Celastrol (2 mg/kg) was intraperitoneally administrated into mice to evaluate hemostasis and thrombosis in vivo. ResultsCelastrol treatment significantly decreased platelet aggregation and secretion of dense or alpha granules induced by collagen-related peptide (CRP) or thrombin in a dose-dependent manner. Additionally, Celastrol-treated platelets showed a dramatically reduced spreading activity and decreased clot retraction. Moreover, Celastrol administration prolonged tail bleeding time and inhibited formation of arterial/venous thrombosis. Furthermore, Celastrol significantly reduced calcium mobilization. ConclusionCelastrol inhibits platelet function and venous/arterial thrombosis, implying that it might be utilized for treating thrombotic diseases.

Platelet functions in lymphatic filariasis patients

Filariasis is a chronic disease where parasitic worms survive in human hosts even for decades and lead to complications like lymphedema and elephantiasis. Despite the persistent existence of filarial parasites in human hosts, fatal and thrombotic complications are not known, unlike other parasitic diseases like malaria. This suggests that filarial parasites might be affecting the host's platelet functions. This study was conducted to examine platelet functions in confirmed filariasis patients and healthy controls. Results showed that filariasis patients had larger platelets, inhibited aggregation, and slower speed of aggregation, compared to controls. However, in vivo markers of platelet activation and degranulation (beta thromboglobulin and soluble P-selectin) were not affected. Observations suggested that there is increased platelet turnover, cellular apoptosis and inhibited platelet functions in filariasis patients compared to controls. Platelet function inhibition was not associated with the duration of disease, lymphedema-affected organs, or gender of patients. This study confirms that filarial parasites modulate platelet functions in human hosts.

Large-scale lipidomics profiling reveals characteristic lipid signatures associated with an increased cardiovascular risk

Abstract Background Patients with cardiovascular disease (CVD) are at high risk to develop adverse events.1 The distinct risk of developing recurring adverse cardiovascular events is not solely explained by traditional risk factors.2-4 Platelets are essentially involved in progression of CVD including coronary artery disease (CAD) and platelet hyperreactivity leads to development of adverse cardiovascular (CV) events.5-7 Alterations in the platelet lipidome are associated with disease severity in CAD and lead to platelet hyperresponsiveness and thus might alter the individual risk profile.8,9 Objective In this study we investigate the platelet lipidome of CAD patients by untargeted lipidomics and elucidate alterations in the lipid composition of patients with recurring adverse cardiovascular events. Methods We characterized the platelet lipidome in a large consecutive CAD cohort (n=1057) by an untargeted lipidomics approach using liquid chromatography coupled to mass spectrometry. Results The platelet lipidome in this study covered 767 lipids and characteristic changes occurred in patients with adverse cardiovascular events. The most prominent upregulated lipids in patients with cardiovascular events primarily belong to the class of phospholipids (lysophosphatidylethanolamines (LPE)) and fatty acyls (acylcarnitines (CAR) and unsaturated fatty acids (FA)). It was striking that patients with ischemic events exclusively showed upregulation of LPE whereas mainly CAR and FA were upregulated in patients with major bleeding events in contrast to patients without CV events (Figure 1 A, B). PCA revealed a major separation of patients with adverse CV events when compared to patients free from any events during follow-up indicating a substantial change in the platelet lipidome of patients with adverse CV events (Figure 1C). Further, upregulated platelet lipids are associated with an increased cardiovascular or bleeding risk and independently predict upcoming adverse events (Figure 2 A, B). Stratification of an increased CV risk in patients with CAD including platelet lipids outperformed conventional risk assessment utilizing conventional lipids measurements (e.g. plasma lipoproteins) (Figure 2 C). In addition, specific alterations of the platelet lipidome, including LPE and CAR are associated with modulation of in vitro platelet functions and thus, might contribute to the development of adverse CV events by promotion or inhibition of platelet functions (Figure 2D, E). Conclusions Our results reveal that the composition of the platelet lipidome is altered in CVD patients with an increased cardiovascular risk and distinct platelet lipids may indicate adverse events. Results of this study may contribute to improved risk discrimination and classification for cardiovascular events in patients with CVD. Further, altered lipid signatures might modulate platelet function and contribute to disease progression and development of adverse CV events in patients with CVD.Figure 1Figure 2

Abstract 13963: Redefining the Assessment of “Therapeutic” Platelet Response to Acetylsalicylic Acid

Background: Despite extensive investigations, the optimal assessment of the “therapeutic response” to acetylsalicylic acid (ASA) remains unclear. Limited information is available on the relation between serum thromboxane (Tx)B 2 ; arachidonic acid (AA)-induced platelet aggregation (PA) by light transmittance aggregometry (LTA); aspirin reaction units (ARU) by VerifyNow aspirin test (VN), and pharmacokinetics (PK). Methods: Serial PD and PK analyses were performed immediately after a single 162 or 650 mg dose of chewed and swallowed ASA in ten healthy volunteers. ASA response was defined as >95% inhibition of serum TxB 2, <550 ARU by VN test and ≤20% AA-induced PA. Correlation analyses between PK and PD measurements and receiver operating characteristic (ROC) curve analyses were performed. Results: ASA Response measured by VN, and AA-induced PA was achieved within 30 minutes of ASA administration. A good correlation was observed between VN ARU and 1 mM AA-induced maximum PA (r=0.80, p<0.001), serum TxB 2 (r=0.76, p<0.001), and inhibition of serum TxB 2 (r=0.87, p<0.001). The relation between platelet aggregation and TxB 2 inhibition appears to be dichotomous, with only modest inhibition of TxB 2 (~50% inhibition) associated with marked inhibition of platelet aggregation. ROC curve analyses indicated that ≤558 ARU and ≤7% AA-induced PA were associated with >95% inhibition of TxB 2 . A plasma ASA 686 ng/mL cut-off was associated with >95% inhibition of serum TxB 2 , ≤7% 1 mM AA-induced PA by LTA, and ≤585 ARU. Conclusion: Our study demonstrated an important relationship between PD and PK parameters measured immediately following oral ASA and cutoff values for VN assay and LTA that is associated with >95% inhibition of serum TxB 2 . We demonstrated that ~50% inhibition of TxB 2 is required to reach high levels of platelet function inhibition.

Addition of aspirin to venous thromboembolism chemoprophylaxis safely decreases venous thromboembolism rates in trauma patients

BackgroundTrauma patients exhibit a multifactorial hypercoagulable state and have increased risk of venous thromboembolism (VTE). Despite early and aggressive chemoprophylaxis (CP) with various heparin compounds (“standard” CP; sCP), VTE rates...

Identification of Plasma Biomarkers from Rheumatoid Arthritis Patients Using an Optimized Sequential Window Acquisition of All THeoretical Mass Spectra (SWATH) Proteomics Workflow.

Rheumatoid arthritis (RA) is a systemic autoimmune and inflammatory disease. Plasma biomarkers are critical for understanding disease mechanisms, treatment effects, and diagnosis. Mass spectrometry-based proteomics is a powerful tool for unbiased biomarker discovery. However, plasma proteomics is significantly hampered by signal interference from high-abundance proteins, low overall protein coverage, and high levels of missing data from data-dependent acquisition (DDA). To achieve quantitative proteomics analysis for plasma samples with a balance of throughput, performance, and cost, we developed a workflow incorporating plate-based high abundance protein depletion and sample preparation, comprehensive peptide spectral library building, and data-independent acquisition (DIA) SWATH mass spectrometry-based methodology. In this study, we analyzed plasma samples from both RA patients and healthy donors. The results showed that the new workflow performance exceeded that of the current state-of-the-art depletion-based plasma proteomic platforms in terms of both data quality and proteome coverage. Proteins from biological processes related to the activation of systemic inflammation, suppression of platelet function, and loss of muscle mass were enriched and differentially expressed in RA. Some plasma proteins, particularly acute-phase reactant proteins, showed great power to distinguish between RA patients and healthy donors. Moreover, protein isoforms in the plasma were also analyzed, providing even deeper proteome coverage. This workflow can serve as a basis for further application in discovering plasma biomarkers of other diseases.

No impact of polymorphism in the phosphodiesterase 5A gene in Cavalier King Charles Spaniels on pimobendan-induced inhibition of platelet aggregation response.

A variant in the canine phosphodiesterase (PDE) 5A gene (PDE5A:E90K) is associated with decreased concentrations of circulating cyclic guanosine monophosphate (cGMP) and response to PDE5 inhibitor treatment. Pimobendan is a PDE inhibitor recommended for medical treatment of certain stages of myxomatous mitral valve disease (MMVD) in dogs. PDE5A:E90K polymorphism attenuates the inhibitory effect of pimobendan on in vitro platelet aggregation and increases basal platelet aggregation in Cavalier King Charles Spaniels (CKCS). Selected clinical variables (MMVD severity, sex, age, hematocrit, platelet count in platelet-rich plasma [PRP], and echocardiographic left ventricular fractional shortening [LV FS]) will not show an association with results. Fifty-two privately owned CKCS with no or preclinical MMVD. Using blood samples, we prospectively assessed PDE5A genotype using Sanger sequencing and adenosine diphosphate-induced platelet aggregation response (area under the curve [AUC], maximal aggregation [MaxA], and velocity [Vel]) with and without pimobendan using light transmission aggregometry. Dogs also underwent echocardiography. Pimobendan inhibited platelet function as measured by AUC, MaxA, and Vel at a concentration of 10 μM (P < .0001) and Vel at 0.03 μM (P < .001). PDE5A:E90K polymorphism did not influence the inhibitory effect of pimobendan or basal platelet aggregation response. The PDE5A:E90K polymorphism did not influence in vitro basal platelet aggregation response or the inhibitory effect of pimobendan on platelet aggregation in CKCS. Dogs with the PDE5A:E90K polymorphism did not appear to have altered platelet function or response to pimobendan treatment.

Differential inhibition of platelet function by cilostazol in combination with clopidogrel.

To assess the antiplatelet effect of cilostazol clinically, we compared the effects of cilostazol in combination with clopidogrel on various platelet function tests. We recruited patients with ischemic stroke at high risk of recurrence who were treated with clopidogrel alone within 180days after stroke onset. Subjects underwent baseline platelet function tests, and were then randomly assigned to receive dual antiplatelet therapy (DAPT) comprising clopidogrel and cilostazol or clopidogrel monotherapy (SAPT). After 6months, platelet function was measured again and compared to that at baseline in each group, and the rate of change was compared between groups. Thirty-four patients were enrolled, but 4 patients were excluded for various reasons. In total, 30 subjects (13 in DAPT and 17 in SAPT group) were analyzed. Adenosine diphosphate- and collagen-induced aggregation, VerifyNow P2Y12 reaction units, vasodilator-stimulated phosphoprotein (platelet reactivity index: PRI) and plasma p-selectin concentration were significantly lower (P = 0.004, 0.042, 0.049, 0.003 and 0.006 respectively), while VerifyNow % inhibition was significantly higher at 6months compared to baseline (P = 0.003) in the DAPT group only. Comparison of the rate of change in each parameter from baseline to 6months showed that while PRI decreased at a greater rate (P = 0.012), VerifyNow % inhibition increased at a greater rate (P = 0.003) in the DAPT group than the SAPT group. The inhibitory effects of adjunctive cilostazol added to clopidogrel on platelet function differed by type of platelet function test. VerifyNow % inhibition and PRI were more inhibited than the other platelet function tests. CSPS.com substudy in TWMU (UMIN000026672), registered on April 1, 2017. This study was performed as a substudy of CSPS.com (UMIN000012180, registered on October 31, 2013) and was retrospectively registered.

The oxylipin analog CS585 prevents platelet activation and thrombosis through activation of the prostacyclin receptor

AbstractCardiovascular disease remains the primary cause of morbidity and mortality globally. Platelet activation is critical for maintaining hemostasis and preventing the leakage of blood cells from the vessel. There has been a paucity in the development of new drugs to target platelet reactivity. Recently, the oxylipin 12(S)-hydroxy-eicosatrienoic acid (12-HETrE), which is produced in platelets, was shown to limit platelet reactivity by activating the prostacyclin receptor. Here, we demonstrated the synthesis of a novel analog of 12-HETrE, known as CS585. Human blood and mouse models of hemostasis and thrombosis were assessed for the ability of CS585 to attenuate platelet activation and thrombosis without increasing the risk of bleeding. Human platelet activation was assessed using aggregometry, flow cytometry, western blot analysis, total thrombus formation analysis system, microfluidic perfusion chamber, and thromboelastography. Hemostasis, thrombosis, and bleeding assays were performed in mice. CS585 was shown to potently target the prostacyclin receptor on the human platelet, resulting in a highly selective and effective mechanism for the prevention of platelet activation. Furthermore, CS585 was shown to inhibit platelet function in human whole blood ex vivo, prevent thrombosis in both small and large vessels in mouse models, and exhibit long-lasting prevention of clot formation. Finally, CS585 was not observed to perturb coagulation or increase the risk of bleeding in the mouse model. Hence, CS585 represents a new validated target for the treatment of thrombotic diseases without the risk of bleeding or off-target activation observed with other prostaglandin receptor agonists.

Effects of orally administered pimobendan on platelet function in healthy adult cats.

Several phosphodiesterase inhibitors have demonstrable antiplatelet actions when administered to human patients. Concentration-dependent inhibition of feline platelet aggregation by pimobendan has been previously demonstrated in vitro. However, there are no published reports characterizing the effect of oral pimobendan, administered at therapeutic doses, on platelet function in cats. This study aimed to evaluate the effect of orally administered pimobendan on platelet function in healthy adult cats. 6 healthy purpose-bred adult cats. Cats were administered pimobendan orally at a dosage of 0.625 mg/cat (low-dose) twice daily for 1 week, followed by 1.25 mg/cat (high-dose) twice daily for 1 week. Venous blood sampling for platelet testing and plasma drug concentration occurred at baseline, 1 hour postdose on the eighth day of treatment with low-dose pimobendan, 1 hour postdose on the eighth day of treatment with high-dose pimobendan, and after a 1-week washout period. Platelet function was assessed by whole blood aggregometry and by use of a platelet function analyzer (PFA-100®). Friedman tests were used to compare platelet function parameters among the 4 sampling timepoints. After 1 week of treatment, median (range) plasma pimobendan concentrations were 15.1 ng/mL (6.89-20.2 ng/mL) and 32.8 ng/mL (23.3-44.8 ng/mL) in cats receiving low-dose and high-dose pimobendan, respectively. No significant differences in PFA closure time or any aggregometry variable were found among the treatment conditions. Pimobendan was not associated with measurable inhibition of platelet function when administered orally to healthy adult cats at 2 clinically relevant dosages.

Aspirin reduces the mortality risk of sepsis-associated acute kidney injury: an observational study using the MIMIC IV database.

Introduction: Sepsis-associated acute kidney injury (SA-AKI) is a complication of sepsis and is characterized by high mortality. Aspirin affects cyclooxygenases which play a significant role in inflammation, hemostasis, and immunological regulation. Sepsis is an uncontrolled inflammatory and procoagulant response to a pathogen, but aspirin can inhibit platelet function to attenuate the inflammatory response, thus improving outcomes. Several studies have generated contradictory evidence regarding the effect of aspirin on patients with sepsis-associated acute kidney injury (SA-AKI). We conducted an analysis of the MIMIC IV database to investigate the correlation between aspirin utilization and the outcomes of patients with SA-AKI, as well as to determine the most effective dosage for aspirin therapy. Materials and methods: SA-AKI patients' clinical data were extracted from MIMIC-IV2.1. Propensity score matching was applied to balance the baseline characteristics between the aspirin group and the non-user group. Subsequently, the relationship between aspirin and patient death was analyzed by Kaplan-Meier method and Cox proportional hazard regression models. Results: 12,091 patients with SA-AKI were extracted from the MIMIC IV database. In the propensity score-matched sample of 7,694 individuals, lower 90-day mortality risks were observed in the aspirin group compared to the non-users group (adjusted HR: 0.722; 95%CI: 0.666, 0.783) by multivariable cox proportional hazards analysis. In addition, the Kaplan-Meier survival curves indicated a superior 90-day survival rate for aspirin users compared to non-users (the log-rank test p-value was 0.001). And the median survival time of patients receiving aspirin treatment was significantly longer than those not receiving (46.47days vs. 24.26days). In the aspirin group, the average ICU stay length was shorter than non-users group. (5.19days vs. 5.58days, p = 0.006). There was no significant association between aspirin and an increased risk of gastrointestinal hemorrhage (p = 0.144). Conclusion: Aspirin might reduce the average ICU stay duration and the 30-day or 90-day mortality risks of SA-AKI patients. No statistically significant difference in the risk of gastrointestinal hemorrhage was found between the aspirin group and the control group.

The particularities of hemostasis in patients with non-ST elevation myocardial infarction and some comorbidities

The formation of an obstructive thrombus within an artery remains a major cause of mortality and morbidity worldwide. [1] Despite effective inhibition of platelet function by modern antiplatelet therapies, these agents fail to fully eliminate atherothrombotic risk. This may well be related to extensive vascular disease, beyond the protective abilities of the treatment agents used. However, recent evidence suggests that residual vascular risk in those treated with modern antiplatelet therapies is related, at least in part, to impaired fibrin clot lysis. Along these lines, thrombosis is the result of several changes in local homeostasis: endothelial dysfunction, changes in the fibrinolytic system, increased content of some coagulation factors, decreased natural inhibitors, platelet hyperactivity [2] [3]. In this review, we attempt to shed more light on the role of hypofibrinolysis in predisposition to arterial vascular events. We provide a brief overview of the coagulation system followed by addressing the role of impaired coagulation, anticoagulation, and fibrinolysis in acute vascular conditions, including coronary artery disease. We also discuss the prognostic implications of coagulation biomarkers regarding arterial thrombotic events, addressing, in particular, people who are exposed to metabolic risks (hyperlipidemia, hypertension, and diabetes). We conclude that affecting coagulation appears to contribute to residual thrombosis risk in individuals with arterial disease on antiplatelet therapy, and targeting proteins in the fibrinolytic and coagulant system represents a viable strategy to improve outcomes in this population. Future work is required to refine the antithrombotic approach by modulating pathological abnormalities in the fibrinolytic and anticoagulant system and tailoring the therapy according to the need of each individual

Dimethyl fumarate possesses antiplatelet and antithrombotic properties

BackgroundDimethyl fumarate (DMF) is a methyl ester of fumaric acid and has been approved for treating multiple sclerosis (MS) and psoriasis due to anti-inflammatory effect. There is a close association between platelets and the pathogenesis of MS. Whether DMF affects platelet function remains unclear. Our study intends to evaluate DMF’s effect on platelet function. MethodsWashed human platelets were treated with different concentrations of DMF (0, 50, 100 and 200 μM) at 37 °C for 1 h followed by analysis of platelet aggregation, granules release, receptors expression, spreading and clot retraction. In addition, mice received intraperitoneal injection of DMF (15 mg/kg) to assess tail bleeding time, arterial and venous thrombosis. ResultsDMF significantly inhibited platelet aggregation and the release of dense/alpha granules in response to collagen-related peptide (CRP) or thrombin stimulation dose-dependently without altering the expression of platelet receptors αIIbβ3, GPIbα, and GPVI. In addition, DMF-treated platelets presented significantly reduced spreading on collagen or fibrinogen and thrombin-mediated clot retraction along with the decreased phosphorylation of c-Src and PLCγ2. Moreover, administration of DMF into mice significantly prolonged the tail bleeding time and impaired arterial and venous thrombus formation. Furthermore, DMF reduced the generation of intracellular reactive oxygen species and calcium mobilization, and inhibited NF-κB activation and the phosphorylation of ERK1/2, p38 and AKT. ConclusionDMF inhibits platelet function and arterial/venous thrombus formation. Considering the presence of thrombotic events in MS, our study indicates that DMF treatment for patients with MS might obtain both anti-inflammatory and anti-thrombotic benefits.

Chemical degradation of BTK/TEC as a novel approach to inhibit platelet function.

Chemical degradation of BTK/TEC as a novel approach to inhibit platelet function.

Proinflammatory microenvironment promotes lymphoma progression in mice with high megakaryocyte and TPO levels.

Platelets have been shown to enhance the survival of lymphoma cell lines. However, it remains unclear whether they play a role in lymphoma. Here, we investigated the potential role of platelets and/or megakaryocytes in the progression of Eμ-myc lymphoma. Eμ-myc tumor cells were transplanted into recipient wild-type (WT) control, Mpl-/-, or TpoTg mice, which exhibited normal, low, and high platelet and megakaryocyte counts, respectively. TpoTg mice that underwent transplantation exhibited enhanced lymphoma progression with increased white blood cell (WBC) counts, spleen and lymph node weights, and enhanced liver infiltration when compared with WT mice. Conversely, tumor-bearing Mpl-/- mice had reduced WBC counts, lymph node weights, and less liver infiltration than WT mice. Using an Mpl-deficient thrombocytopenic immunocompromised mouse model, our results were confirmed using the human non-Hodgkin lymphoma GRANTA cell line. Although we found that platelets and platelet-released molecules supported Eμ-myc tumor cell survival invitro, pharmacological inhibition of platelet function or anticoagulation in WT mice transplanted with Eμ-myc did not improve disease outcome. Furthermore, transient platelet depletion or sustained Bcl-xL-dependent thrombocytopenia did not alter lymphoma progression. Cytokine analysis of the bone marrow fluid microenvironment revealed increased levels of the proinflammatory molecule interleukin 1 in TpoTg mice, whereas these levels were lower in Mpl-/- mice. Moreover, RNA sequencing of blood-resident Eμ-myc lymphoma cells from TpoTg and WT mice after tumor transplantation revealed the upregulation of hallmark gene sets associated with an inflammatory response in TpoTg mice. We propose that the proinflammatory microenvironment in TpoTg mice promotes lymphoma progression.

Mitochondrial calcium uniporter b deletion inhibits platelet function and reduces susceptibility to arterial thrombosis

BackgroundMitochondrial calcium uniporter b (MCUb) is a negative regulator of the mitochondrial calcium uniporter (MCU) and is known to limit mitochondrial calcium ion (Ca2+) uptake. The role of MCUb in platelet function remains unclear. ObjectivesUtilizing MCUb−/− mice, we examined the role of MCUb in regulating platelet function and thrombosis. MethodsPlatelet activation was evaluated in agonist-induced standardized in vitro assays. Susceptibility to arterial thrombosis was evaluated in FeCl3 injury–induced carotid artery and laser injury–induced mesenteric artery thrombosis models. The glycolytic proton efflux rate and oxygen consumption rate were measured to evaluate aerobic glycolysis. ResultsUpon stimulation, MCUb−/− platelets exhibited reduced cytoplasmic Ca2+ responses concomitant with increased mitochondrial Ca2+ uptake. MCUb−/− platelets displayed reduced agonist-induced platelet aggregation and spreading on fibrinogen and decreased α and dense-granule secretion and clot retraction. MCUb−/− mice were less susceptible to arterial thrombosis in FeCl3 injury–induced carotid and laser injury–induced mesenteric thrombosis models with unaltered tail bleeding time. In adoptive transfer experiments, thrombocytopenic hIL-4Rα/GPIbα-transgenic mice transfused with MCUb−/− platelets were less susceptible to FeCl3 injury-induced carotid thrombosis compared with hIL-4Rα/GPIbα-Tg mice transfused with wild type platelets, suggesting a platelet-specific role of MCUb in thrombosis. MCUb−/− stimulated platelets exhibited reduced glucose uptake, decreased glycolytic rate, and lowered pyruvate dehydrogenase phosphorylation, suggesting that mitochondrial Ca2+ mediates bioenergetic changes in platelets. ConclusionOur findings suggest that mitochondrial Ca2+ signaling and glucose oxidation are functionally linked in activated platelets and reveal a novel role of MCUb in platelet activation and arterial thrombosis.