Reactive Oxygen Species

The platelet-mitochondria nexus in autoimmune and musculoskeletal diseases

Platelets are crucial for thrombosis and hemostasis. Importantly, they contain mitochondria that are responsible for energy generation and therefore vital for platelet survival and activation. Activated platelets can release mitochondria that may be free or encapsulated in platelet extracellular vesicles (EVs). Extruded mitochondria are a well-known source of mitochondrial DNA, and mitochondrial antigens that can be targeted by autoantibodies forming immune complexes (IC). Interaction of IC with the platelet cell surface FcγRIIA receptor results in platelet activation and release of platelet granule components. In this review, we summarize how platelets and mitochondria may contribute to the pathogenesis of different autoimmune and musculoskeletal diseases. Targeting key drivers of mitochondrial extrusion may ultimately lead to urgently needed targeted pharmacological interventions for treating inflammation and thrombotic diathesis, and halting organ damage in some of these rheumatological conditions.

One immune cell to bind them all: platelet contribution to neurodegenerative disease

Alzheimer's disease (AD) and related dementias (ADRD) collectively affect a significant portion of the aging population worldwide. The pathological progression of AD involves not only the classical hallmarks of amyloid beta (Aβ) plaque buildup and neurofibrillary tangle development but also the effects of vasculature and chronic inflammatory processes. Recently, platelets have emerged as central players in systemic and neuroinflammation. Studies have shown that patients with altered platelet receptor expression exhibit accelerated cognitive decline independent of traditional risk factors. Additionally, platelets from AD patients exhibit heightened unstimulated activation compared to control groups. Platelet granules contain crucial AD-related proteins like tau and amyloid precursor protein (APP). Dysregulation of platelet exocytosis contributes to disease phenotypes characterized by increased bleeding, stroke, and cognitive decline risk. Recent studies have indicated that these effects are not associated with the quantity of platelets present in circulation. This underscores the hypothesis that disruptions in platelet-mediated inflammation and healing processes may play a crucial role in the development of ADRD. A thorough look at platelets, encompassing their receptors, secreted molecules, and diverse roles in inflammatory interactions with other cells in the circulatory system in AD and ADRD, holds promising prospects for disease management and intervention. This review discusses the pivotal roles of platelets in ADRD.

Site-specific thrombus formation: advancements in photothrombosis-on-a-chip technology

Thrombosis, characterized by blood clot formation within vessels, poses a significant medical challenge. Despite extensive research, the development of effective thrombosis therapies is hindered by substantial costs, lengthy development times, and high failure rates in medication commercialization. Conventional pre-clinical models often oversimplify cardiovascular disease, leading to a disparity between experimental results and human physiological responses. In response, we have engineered a photothrombosis-on-a-chip system. This microfluidic model integrates human endothelium, human whole blood, and blood flow dynamics and employs the photothrombotic method. It enables precise, site-specific thrombus induction through controlled laser irradiation, effectively mimicking both normal and thrombotic physiological conditions on a single chip. Additionally, the system allows for the fine-tuning of thrombus occlusion levels via laser parameter adjustments, offering a flexible thrombus model with varying degrees of obstruction. Additionally, the formation and progression of thrombosis noted on the chip closely resemble the thrombotic conditions observed in mice in previous studies. In the experiments, we perfused recalcified whole blood with Rose Bengal into an endothelialized microchannel and initiated photothrombosis using green laser irradiation. Various imaging methods verified the model's ability to precisely control thrombus formation and occlusion levels. The effectiveness of clinical drugs, including heparin and rt-PA, was assessed, confirming the chip's potential in drug screening applications. In summary, the photothrombosis-on-a-chip system significantly advances human thrombosis modeling. Its precise control over thrombus formation, flexibility in the thrombus severity levels, and capability to simulate dual physiological states on a single platform make it an invaluable tool for targeted drug testing, furthering the development of organ-on-a-chip drug screening techniques.

Investigating the role of rotenone on human blood platelets: Molecular insights into abnormal platelet functions in Parkinson's disease

Parkinson's disease (PD) is a predominant neuromotor disorder characterized by the selective death of dopaminergic neurons in the midbrain. The majority of PD cases are sporadic or idiopathic, with environmental toxins and pollutants potentially contributing to its development or exacerbation. However, clinical PD patients are often associated with a reduced stroke frequency, where circulating blood platelets are indispensable. Although platelet structural impairment is evident in PD, the platelet functional alterations and their underlying molecular mechanisms are still obscure. Therefore, we investigated rotenone (ROT), an environmental neurotoxin that selectively destroys dopaminergic neurons mimicking PD, on human blood platelets to explore its impact on platelet functions, thus replicating PD conditions in vitro. Our study deciphered that ROT decreased thrombin-induced platelet functions, including adhesion, activation, secretion, and aggregation in human blood platelets. As ROT is primarily responsible for generating intracellular reactive oxygen species (ROS), and ROS is a key player regulating the platelet functional parameters, we went on to check the effect of ROT on platelet ROS production. In our investigation, it became evident that ROT treatment resulted in the stimulation of ROS production in human blood platelets. Additionally, we discovered that ROT induced ROS production by augmenting Ca2+ mobilization from inositol 1,4,5-trisphosphate receptor. Apart from this, the treatment of ROT triggers protein kinase C associated NADPH oxidase-mediated ROS production in platelets. In summary, this research, for the first time, highlights ROT-induced abnormal platelet functions and may provide a mechanistic insight into the altered platelet activities observed in PD patients.

Redox regulation of platelet function and thrombosis

Platelets are well-known players in several cardiovascular diseases such as atherosclerosis and venous thrombosis. There is increasing evidence demonstrating that reactive oxygen species (ROS) are generated within activated platelets. Nicotinamide adenine dinucleotide phosphate oxidase (NOX) is a major source of ROS generation in platelets. Ligand binding to platelet receptor glycoprotein (GP) VI stimulates intracellular ROS generation consisting of a spleen tyrosine kinase-independent production involving NOX activation and a following spleen tyrosine kinase-dependent generation. In addition to GPVI, stimulation of platelet thrombin receptors (protease-activated receptors [PARs]) can also trigger NOX-derived ROS production. Our recent study found that mitochondria-derived ROS production can be induced by engagement of thrombin receptors but not by GPVI, indicating that mitochondria are another source of PAR-dependent ROS generation apart from NOX. However, mitochondria are not involved in GPVI-dependent ROS generation. Once generated, the intracellular ROS are also involved in modulating platelet function and thrombus formation; therefore, the site-specific targeting of ROS production or clearance of excess ROS within platelets is a potential intervention and treatment option for thrombotic events. In this review, we will summarize the signaling pathways involving regulation of platelet ROS production and their role in platelet function and thrombosis, with a focus on GPVI- and PAR-dependent platelet responses.

Ultrasound Trigger Ce-Based MOF Nanoenzyme For Efficient Thrombolytic Therapy

The inflammatory damage caused by thrombus formation and dissolution can increase the risk of thrombotic complications on top of cell death and organ dysfunction caused by thrombus itself. Therefore, a rapid and precise thrombolytic therapy strategy is in urgent need to effectively dissolve thrombus and resist oxidation simultaneously. In this study, Ce-UiO-66, a cerium-based metal-organic framework (Ce-MOF) with reactive oxygen species (ROS) scavenging properties, encapsulated by low-immunogenic mesenchymal stem cell membrane with inflammation-targeting properties, is used to construct a targeted nanomedicine Ce-UiO-CM. Ce-UiO-CM is applied in combination with external ultrasound stimulation for thrombolytic therapy in rat femoral artery. Ce-UiO-66 has abundant Ce (III)/Ce (IV) coupling sites that react with hydrogen peroxide (H2O2) to produce oxygen, exhibiting catalase (CAT) activity. The multi-cavity structure of Ce-UiO-66 can generate electron holes, and its pore channels can act as micro-reactors to further enhance its ROS scavenging capacity. Additionally, the porous structure of Ce-UiO-66 and the oxygen produced by its reaction with H2O2 may enhance the cavitation effects of ultrasound, thereby improving thrombolysis efficacy.

The association of the platelet/high-density lipoprotein cholesterol ratio with self-reported stroke and cardiovascular mortality: a population-based observational study

BACKGROUND

Previous studies have shown that the relationship between high-density lipoprotein cholesterol (HDL-C) and stroke is controversial, and the association between the platelet/high-density lipoprotein cholesterol ratio (PHR), a novel marker for inflammation and hypercoagulability states, and stroke has not been established.

METHODS

This study presents an analysis of cross-sectional data from the 2005-2018 National Health and Nutrition Examination Survey (NHANES). Stroke history, HDL-C levels, and platelet counts were obtained during cross-sectional surveys. The PHR was calculated as the ratio of the number of platelets to HDL-C concentration. Weighted logistic regression was used to assess the associations of HDL-C and the PHR with stroke. Nonlinearity of this relationship was determined through restricted cubic splines (RCSs) and two-piecewise linear regression for identifying inflection points. Furthermore, Cox regression was utilized to prospectively analyze the associations of the PHR and HDL-C concentration with cardiovascular disease (CVD) mortality in stroke survivors.

RESULTS

A total of 27,301 eligible participants were included in the study; mean age, 47.28 years and 50.57% were female, among whom 1,040 had a history of stroke. After full adjustment, the odds ratio (OR) of stroke associated with a per standard deviation (SD) increase in the PHR was estimated at 1.13 (95% confidence interval (CI): 1.03 - 1.24, P = 0.01), and the OR of stroke associated with a per SD increase in HDL-C was 0.95 (95% CI: 0.86-1.05, P = 0.30). The RCS indicated a nonlinear relationship for both variables (PPHR = 0.018 and PHDL-C = 0.003), and further piecewise linear regression identified inflection points at PHR = 223.684 and HDL-C = 1.4 mmol/L. Segmental regression indicated that in the PHR ≥ 223.684 segment, the estimated OR of stroke associated with a per-SD increase in the PHR was 1.20 (95% CI: 1.09 - 1.31, P < 0.001), while the association of stroke with HDL-C was not significant before or after the inflection point (P > 0.05). Furthermore, Cox regression and RCS showed that a per-SD increase in the PHR was linearly associated with a greater risk of CVD mortality among stroke survivors (HR: 1.14, 95% CI: 1.06 - 1.22, P < 0.001; nonlinear, P = 0.956), while HDL-C was not significantly associated with CVD mortality.

CONCLUSION

The association between the PHR and stroke incidence exhibited a significant threshold effect, with an inflection point at 223.684. A PHR exceeding 223.684 was positively associated with stroke, while the association between HDL-C and stroke was not significant. Additionally, the PHR was positively and linearly associated with CVD mortality among stroke survivors.

Gestational diabetes mellitus is associated with in vivo platelet activation and platelet hyperreactivity

BACKGROUND

Gestational diabetes mellitus is associated with obstetrical and long-term cardiovascular complications. Although platelet hyperresponsiveness in type-2 diabetes mellitus has been well characterized and has been shown to play a crucial role in cardiovascular complications, this aspect has been little studied in gestational diabetes mellitus.

OBJECTIVE

We aimed to evaluate platelet reactivity, in vivo platelet activation, and endothelial function in gestational diabetes mellitus in comparison with normal pregnancy.

STUDY DESIGN

This was a prospective, case-control study of 23 women with gestational diabetes mellitus and 23 healthy pregnant women who were studied at 26 to 28 and 34 to 36 weeks of gestation and at 8 weeks postpartum. Platelet reactivity and in vivo platelet activation, including light transmission aggregometry, PFA-100, platelet activation antigen expression, platelet adhesion under flow, platelet nitric oxide and reactive oxygen species production, and endothelial dysfunction markers, were assessed.

RESULTS

The study of platelet function showed a condition of platelet hyperreactivity in cases with gestational diabetes mellitus when compared with healthy pregnant women at enrollment, which was further enhanced at the end of pregnancy and tended to decrease 2 months after delivery, although it still remained higher in gestational diabetes mellitus. In vivo platelet activation was also evident in gestational diabetes mellitus, especially at the end of pregnancy, in part persisting up to 8 weeks after delivery. Finally, women with gestational diabetes mellitus showed defective platelet nitric oxide production and endothelial dysfunction when compared with healthy pregnancies.

CONCLUSION

Our data showed that gestational diabetes mellitus generates a condition of platelet hyperreactivity that in part persists up to 2 months after delivery. Impaired platelet sensitivity to nitric oxide and reduced platelet and endothelial nitric oxide production may contribute to the platelet hyperreactivity condition. Platelet hyperreactivity may play a role in the long-term cardiovascular complications of gestational diabetes mellitus women.

Engineering Platelet Membrane Imitating Nanoparticles for Targeted Therapeutic Delivery

Platelet Membrane Imitating Nanoparticles (PMINs) is a novel drug delivery system that imitates the structure and functionality of platelet membranes. PMINs imitate surface markers of platelets to target specific cells and transport therapeutic cargo. PMINs are engineered by incorporating the drug into the platelet membrane and encapsulating it in a nanoparticle scaffold. This allows PMINs to circulate in the bloodstream and bind to target cells with high specificity, reducing off-target effects and improving therapeutic efficacy. The engineering of PMINs entails several stages, including the separation and purification of platelet membranes, the integration of therapeutic cargo into the membrane, and the encapsulation of the membrane in a nanoparticle scaffold. In addition to being involved in a few pathological conditions including cancer, atherosclerosis, and rheumatoid arthritis, platelets are crucial to the body's physiological processes. This study includes the preparation and characterization of platelet membrane-like nanoparticles and focuses on their most recent advancements in targeted therapy for conditions, including cancer, immunological disorders, atherosclerosis, phototherapy, etc. PMINs are a potential drug delivery system that combines the advantages of platelet membranes with nanoparticles. The capacity to create PMMNs with particular therapeutic cargo and surface markers provides new possibilities for targeted medication administration and might completely change the way that medicine is practiced. Despite the need for more studies to optimize the engineering process and evaluate the effectiveness and safety of PMINs in clinical trials, this technology has a lot of potential.

NOX-2 Inhibitors may be Potential Drug Candidates for the Management of COVID-19 Complications

COVID-19 is an RNA virus that attacks the targeting organs, which express angiotensin- converting enzyme-2 (ACE-2), such as the lungs, heart, renal system, and gastrointestinal tract. The virus that enters the cell by endocytosis triggers ROS production within the confines of endosomes via a NOX-2 containing NADPH-oxidase. Various isoforms of NADPH oxidase are expressed in airways and alveolar epithelial cells, endothelial and vascular smooth muscle cells, and inflammatory cells, such as alveolar macrophages, monocytes, neutrophils, and Tlymphocytes. The key NOX isoform expressed in macrophages and neutrophils is the NOX-2 oxidase, whereas, in airways and alveolar epithelial cells, it appears to be NOX-1 and NOX-2. The respiratory RNA viruses induce NOX-2-mediated ROS production in the endosomes of alveolar macrophages. The mitochondrial and NADPH oxidase (NOX) generated ROS can enhance TGF-β signaling to promote fibrosis of the lungs. The endothelium-derived ROS and platelet-derived ROS, due to activation of the NADPH-oxidase enzyme, play a crucial role in platelet activation. It has been observed that NOX-2 is generally activated in COVID-19 patients. The post-COVID complications like pulmonary fibrosis and platelet aggregation may be due to the activation of NOX-2. NOX-2 inhibitors may be a useful drug candidate to prevent COVID-19 complications like pulmonary fibrosis and platelet aggregation.

Effects of Platelet Count on Blood Pressure: Evidence from Observational and Genetic Investigations

Platelet count has been associated with blood pressure, but whether this association reflects causality remains unclear. To strengthen the evidence, we conducted a traditional observational analysis in the Lifelines Cohort Study (n = 167,785), and performed bi-directional Mendelian randomization (MR) with summary GWAS data from the UK Biobank (n = 350,475) and the International Consortium of Blood Pressure (ICBP) (n = 299,024). Observational analyses showed positive associations between platelet count and blood pressure (OR = 1.12 per SD, 95% CI: 1.10 to 1.14 for hypertension; B = 0.07, 95% CI: 0.07 to 0.08 for SBP; B = 0.07 per SD, 95% CI: 0.06 to 0.07 for DBP). In MR, a genetically predicted higher platelet count was associated with higher SBP (B = 0.02 per SD, 95% CI = 0.00 to 0.04) and DBP (B = 0.03 per SD, 95% CI = 0.01 to 0.05). IVW models and sensitivity analyses of the association between platelet count and DBP were consistent, but not all sensitivity analyses were statistically significant for the platelet count-SBP relation. Our findings indicate that platelet count has modest but significant effects on SBP and DBP, suggesting causality and providing further insight into the pathophysiology of hypertension.

Ayurvedic preparations of Raudra Rasa inhibit agonist-mediated platelet activation and restrict thrombogenicity without affecting cell viability

Ayurveda is considered to be one of the most ancient forms of medicine still practiced. The Ayurvedic preparation Raudra Rasa and its derivatives have been widely employed against cancer since the 12th century, but the effect of these traditional formulations on platelet function and signaling has not previously been examined. Here we demonstrate that Raudra Rasa and its derivatives significantly reduce thrombin-induced integrin activation and granule secretion in platelets, as observed by reduced PAC-1 binding and P-selectin externalization, respectively. These formulations also inhibited thrombin-stimulated phosphatidylserine exposure, mitochondrial reactive oxygen species generation, and mitochondrial transmembrane potential in platelets. Consistent with the above, Raudra Rasa significantly reduced thrombin-induced tyrosine phosphorylation of the platelet proteins, as well as phosphorylation of the enzymes AKT and GSK-3β. In summary, Raudra Rasa inhibits agonist-mediated platelet activation without affecting cell viability, suggesting it may have therapeutic potential as an anti-platelet/anti-thrombotic agent.

Platelets as Potential Non-Traditional Cardiovascular Risk Factor-Analysis Performed in Healthy Donors

Abnormal lipid profile, increased glucose level, and elevated body weight are traditional cardiometabolic risk factors; however, the role of platelets in the development of cardiovascular disease (CVD) is increasingly being highlighted. The aim of this study was to select platelet-related parameters (non-genetic molecular and routine laboratory measurements) that may be associated with increased cardiovascular risk among healthy populations. We evaluated the level of platelet indices, platelet-based inflammatory markers, platelet reactivity parameters, and platelet reactive oxygen species (ROS) generation in relation to selected cardiometabolic risk factors. We noted the association between total cholesterol and LDL cholesterol with platelet aggregation and platelet ROS generation. We found the relationship between triglycerides, glucose, and body mass index with the relatively new multi-inflammatory indices (MII-1 and MII-3). Moreover, we noticed that the mean platelet volume-to-lymphocyte ratio in healthy subjects is not a good source of information about platelets and inflammation. We also highlighted that platelet-to-HDL-cholesterol ratio may be a promising prognostic cardiometabolic indicator. The association between platelet-related (especially molecular) and cardiometabolic parameters requires further research. However, the goal of this study was to shed light on the consideration of platelets as a non-traditional cardiovascular risk factor and a crucial element in identifying individuals at high-risk of developing CVD in the future.

Liposomal Resveratrol Alleviates Platelet Storage Lesion via Antioxidation and the Physical Buffering Effect

Platelet transfusion is essential in the treatment of platelet-related diseases and the prevention of bleeding in patients with surgical procedures. Platelet transfusion efficacy and shelf life are limited mainly by the development of platelet storage lesion (PSL). Mitigating PSL is the key to prolonging the platelet shelf life and reducing wastage. Excess intracellular reactive oxygen species (ROS) are one of the main factors causing PSL. In this study, we explored a nanomedicine strategy to improve the quality and functions of platelets in storage. Resveratrol (Res), a natural plant product, is known for its antioxidative effect. However, medical applications of Res are limited due to its low water solubility and stability. Therefore, we used a resveratrol-loaded liposomal system (Res-Lipo) to better utilize the antioxidant effect of the drug. This study aimed to evaluate the effect of Res-Lipo on platelet oxidative stress and alleviation of PSL during the storage time. Res-Lipo scavenged intracellular ROS and inhibited platelet apoptosis and activation during storage. Res-Lipo not only maintained mitochondrial function but also improved platelet aggregation in response to adenosine 5'-diphosphate. These results revealed that Res-Lipo ameliorated PSL and prolonged the platelet survival time in vivo. The strategy provides a potential method for extending the platelet storage time and might be considered a potential and safe additive to alleviate PSL.

Gas plasma-induced platelet activation corresponds to reactive species profiles and lipid oxidation

Surgical-induced hemostasis is a critical step in the closure of incisions, which is frequently achieved via electrocauterization and subsequent tissue necrotization. The latter is associated with postoperative complications. Recent in vivo work suggested reactive species-producing gas plasma technology as a pro-homeostatic agent acting via platelet activation. However, it remained elusive how platelet activation is linked to lipid and protein oxidation and the reactive species compositions. A direct relation between the reactive species composition and platelet activation was revealed by assessing the production of several reactive species and by using antioxidants. In addition, platelet lipidome and proteome analysis identified significantly regulated key lipids in the platelet activation pathway, such as diacylglycerols and phosphatidylinositol as well as oxylipins like thromboxanes. Lipid oxidation products mainly derived from phosphatidylethanolamine and phosphatidylserine species were observed at modest levels. In addition, oxidative post-translational modifications were identified on key proteins of the hemostasis machinery. This study provides new insights into oxidation-induced platelet activation in general and suggests a potential role of those processes in gas plasma-mediated hemostasis in particular.

Platelet mitochondria: the mighty few

PURPOSE OF REVIEW

Platelet mitochondrial dysfunction is both caused by, as well as a source of oxidative stress. Oxidative stress is a key hallmark of metabolic disorders such as dyslipidemia and diabetes, which are known to have higher risks for thrombotic complications.

RECENT FINDINGS

Increasing evidence supports a critical role for platelet mitochondria beyond energy production and apoptosis. Mitochondria are key regulators of reactive oxygen species and procoagulant platelets, which both contribute to pathological thrombosis. Studies targeting platelet mitochondrial pathways have reported promising results suggesting antithrombotic effects with limited impact on hemostasis in animal models.

SUMMARY

Targeting platelet mitochondria holds promise for the reduction of thrombotic complications in patients with metabolic disorders. Future studies should aim at validating these preclinical findings and translate them to the clinic.

What do we know about platelets in myocardial ischemia-reperfusion injury and why is it important?

Myocardial ischemia-reperfusion injury (MIRI), the joint result of ischemic injury and reperfusion injury, is associated with poor outcomes in patients with acute myocardial infarction undergoing primary percutaneous coronary intervention. Accumulating evidence demonstrates that activated platelets directly contribute to the pathogenesis of MIRI through participating in the formation of microthrombi, interaction with leukocytes, secretion of active substances, constriction of microvasculature, and activation of spinal afferent nerves. The molecular mechanisms underlying the above detrimental effects of activated platelets include the homotypic and heterotypic interactions through surface receptors, transduction of intracellular signals, and secretion of active substances. Revealing the roles of platelet activation in MIRI and the associated mechanisms would provide potential targets/strategies for the clinical evaluation and treatment of MIRI. Further studies are needed to characterize the temporal (ischemia phase vs. reperfusion phase) and spatial (systemic vs. local) distributions of platelet activation in MIRI by multi-omics strategies. To improve the likelihood of translating novel cardioprotective interventions into clinical practice, basic researches maximally replicating the complexity of clinical scenarios would be necessary.

N-acetylcysteine Amide AD4/NACA and Thioredoxin Mimetic Peptides Inhibit Platelet Aggregation and Protect against Oxidative Stress

In the present study, we tested the effect of small-molecular-weight redox molecules on collagen-induced platelet aggregation. We used N-acetylcysteine amide (AD4/NACA), the amide form of N-acetylcysteine (NAC), a thiol antioxidant with improved lipophilicity and bioavailability compared to NAC, and the thioredoxin-mimetic (TXM) peptides, TXM-CB3, TXM-CB13, and TXM-CB30. All compounds significantly inhibited platelet aggregation induced by collagen, with TXM-peptides and AD4 being more effective than NAC. The levels of TxB₂ and 12-HETE, the main metabolites derived from the cyclooxygenase and lipoxygenase pathways following platelet activation, were significantly reduced in the presence of AD4, TXM peptides, or NAC, when tested at the highest concentration (0.6 mM). The effects of AD4, TXM-peptides, and NAC were also tested on the clotting time (CT) of whole blood. TXM-CB3 and TXM-CB30 showed the greatest increase in CT. Furthermore, two representative compounds, TXM-CB3 and NAC, showed an increase in the anti-oxidant free sulfhydryl groups of plasma detected via Ellman's method, suggesting a contribution of plasma factors to the antiaggregating effects. Our results suggest that these small-molecular-weight redox peptides might become useful for the prevention and/or treatment of oxidative stress conditions associated with platelet activation.

Unveiling the mechanism of platelet dysfunction in Parkinson's disease: The effect of 6-hydroxydopamine on human blood platelets

INTRODUCTION

Parkinson's disease (PD) is a progressive neuronal illness often linked to increased cardiovascular complications, such as myocardial infarction, cardiomyopathy, congestive heart failure, and coronary heart disease. Platelets, which are the essential components of circulating blood, are considered potential players in regulating these complications, as platelet dysfunction is evident in PD. These tiny blood cell fragments are supposed to play a crucial role in these complications, but the underlying molecular processes are still obscure.

METHODS

To gain a better understanding of platelet dysfunction in PD, we investigated the impact of 6-hydroxydopamine (6-OHDA), an analog of dopamine that simulates PD by destroying dopaminergic neurons, on human blood platelets. The levels of intraplatelet reactive oxygen species (ROS) were assessed using H₂DCF-DA (20 μM), while mitochondrial ROS was evaluated using MitoSOX™ Red (5 μM), and intracellular Ca²⁺ was measured with Fluo-4-AM (5 μM). The data were acquired through the use of both a multimode plate reader and a laser-scanning confocal microscope.

RESULTS

Our findings showed that 6-OHDA treatment increased the production of ROS in human blood platelets. The increase in ROS was confirmed by the ROS scavenger, NAC, and was also reduced by inhibiting the NOX enzyme with apocynin. Additionally, 6-OHDA potentiated mitochondrial ROS production in platelets. Furthermore, 6-OHDA triggered the intraplatelet Ca²⁺ elevation. This effect was mitigated by the Ca²⁺ chelator BAPTA, which decreased the ROS production triggered by 6-OHDA in human blood platelets, while the IP₃ receptor blocker, 2-APB, reduced the formation of ROS induced by 6-OHDA.

CONCLUSION

Our findings suggest that the 6-OHDA-induced ROS production is regulated by the IP₃ receptor-Ca²⁺-NOX signaling axis in human blood platelets, where the platelet mitochondria also play a significant role. This observation provides a crucial mechanistic understanding of the altered platelet activities that are commonly observed in PD patients.

Research progress on the interaction between oxidative stress and platelets: Another avenue for cancer?

Oxidative stress (OS) is a chemical imbalance between an oxidant and an antioxidant, causing damage to redox signaling and control or causing molecular damage. Unbalanced oxidative metabolism can produce excessive reactive oxygen species (ROS). These excess ROS can cause drastic changes in platelet metabolism and further affect platelet function. It will also lead to an increase in platelet procoagulant phenotype and cell apoptosis, which will increase the risk of thrombosis. The creation of ROS and subsequent platelet activation, adhesion, and recruitment are then further encouraged in an auto-amplifying loop by ROS produced from platelets. Meanwhile, cancer cells produce a higher concentration of ROS due to their fast metabolism and high proliferation rate. However, excessive ROS can result in damage to and modification of cellular macromolecules. The formation of cancer and its progression is strongly associated with oxidative stress and the resulting oxidative damage. In addition, platelets are an important part of the tumor microenvironment, and there is a significant cross-communication between platelets and cancer cells. Cancer cells alter the activation status of platelets, their RNA spectrum, proteome, and other properties. The "cloaking" of cancer cells by platelets providing physical protection，avoiding destruction from shear stress and the attack of immune cells, promoting tumor cell invasion.We explored the vicious circle interaction between ROS, platelets, and cancer in this review, and we believe that ROS can play a stimulative role in tumor growth and metastasis through platelets.

Pyroptosis in platelets: Thrombocytopenia and inflammation

OBJECTIVE

The purpose of this manuscript was to conclude the role of platelets in immune inflammation and discuss the complex mechanisms of pyroptosis in platelets as well as their related diseases.

METHODS

This article reviewed the existing literature to see the development of pyroptosis in platelets.

RESULTS

Platelets have been shown to be capable of activating inflammasomes assembled from NOD-like receptor family pyrin domain containing 3 (NLRP3), apoptosis-associated speck-like protein containing a CARD (ASC) and caspase-1. Recently, they were also implicated in pyroptosis. Cleaved by caspase-1, N-terminal gasdermin D (N-GSDMD) could form pores in the cell membrane, inducing nonselective intracellular substance release. This programmed cell death induced thrombocytopenia and inflammatory cytokine release such as IL-1β and IL-18, promoting platelet aggregation, vaso-occlusion, endothelial permeability and cascaded inflammatory response.

CONCLUSION

Pyroptosis in platelets contributes to thrombocytopenia and inflammation.

Platelets and Cardioprotection: The Role of Nitric Oxide and Carbon Oxide

Nitric oxide (NO) and carbon monoxide (CO) represent a pair of biologically active gases with an increasingly well-defined range of effects on circulating platelets. These gases interact with platelets and cells in the vessels and heart and exert fundamentally similar biological effects, albeit through different mechanisms and with some peculiarity. Within the cardiovascular system, for example, the gases are predominantly vasodilators and exert antiaggregatory effects, and are protective against damage in myocardial ischemia-reperfusion injury. Indeed, NO is an important vasodilator acting on vascular smooth muscle and is able to inhibit platelet activation. NO reacts with superoxide anion (O₂(^-•)) to form peroxynitrite (ONOO(^-)), a nitrosating agent capable of inducing oxidative/nitrative signaling and stress both at cardiovascular, platelet, and plasma levels. CO reduces platelet reactivity, therefore it is an anticoagulant, but it also has some cardioprotective and procoagulant properties. This review article summarizes current knowledge on the platelets and roles of gas mediators (NO, and CO) in cardioprotection. In particular, we aim to examine the link and interactions between platelets, NO, and CO and cardioprotective pathways.

H2O2-triggered "off/on signal" nanoparticles target P-selectin for the non-invasive and contrast-enhanced theranostics for arterial thrombosis

Pathological coagulation within an injured artery and the subsequent cardiovascular complications, such as stroke and heart attack, greatly threaten human life. Inspired by the biochemical features of acute arterial thrombosis, such as abundant activated platelets and hydrogen peroxide (H₂O₂), we constructed platelet-targeted theranostic nanoparticles (CyBA/PFM NPs) with H₂O₂-triggered photoacoustic contrast enhancement and antithrombotic capabilities. CyBA/PFM NPs were designed to target platelet-rich clots via fucoidan segment within the carrier, which could be activated by H₂O₂ to produce fluorescent "CyOH" molecules, thus turning on the photoacoustic signal. CyBA/PFM NPs showed obvious amplification of fluorescence following incubation with fresh clots, exhibiting efficient scavenging ability of intracellular reactive oxygen species (ROS). In a FeCl₃-induced mouse model of carotid thrombosis, CyBA/PFM NPs significantly amplified the photoacoustic contrast in thrombogenic tissues, effectively eliminated ROS within the occlusion site, and suppressed the thrombus formation, accompanied by a normalization of the soluble CD40L level. Given their accurate imaging potential, potent antithrombotic activities and acceptable biosafety, CyBA/PFM NPs hold strong potential as nanoscale theranostics for H₂O₂-correlated cardiovascular diseases. STATEMENT OF SIGNIFICANCE: In this study, we developed a platelet-targeted and H₂O₂-triggered nanosystem self-assembled from phenylboronated fucoidan/maltodextrin polymers and responsive near-infrared probes. The fucoidan segment within the carrier could facilitate the specific delivery of the therapeutic polymers and probes to the platelet-rich arterial thrombus. In a mouse model of FeCl₃-induced arterial thrombosis, the system could be activated by H₂O₂ to produce fluorescent "CyOH" molecules, thus turning on the photoacoustic signal and specifically imaging thrombosed tissues. Besides, CyBA/PFM NPs significantly effectively eliminated ROS within the occlusion site and suppressed the thrombus formation. Given their theranostic potential and acceptable biosafety, this system has great potential for H₂O₂-correlated cardiovascular diseases.

Application of Nanotechnology in Thrombus Therapy

A thrombus is a blood clot that forms in the lumen of an artery or vein, restricting blood flow and causing clinical symptoms. Thrombosis is associated with many life-threatening cardiovascular diseases. However, current clinical therapeutic technologies still have many problems in targeting, enrichment, penetration, and safety to meet the thrombosis treatment needs. Therefore, researchers devote themselves to developing nanosystems loaded with antithrombotic drugs to address this paradox in recent years. Herein, the existing thrombosis treatment technologies are first reviewed; and then, their advantages and disadvantages are outlined based on a brief discussion of thrombosis's definition and formation mechanism. Furthermore, the need and application cases for introducing nanotechnology are discussed, focusing on thrombus-specific targeted ligand modification technology and microenvironment-triggered responsive drug release technology. Then, nanomaterials that can be used to design antithrombotic nanotherapeutic systems are summarized. Moreover, a variety of drug delivery technologies driven by nanomotors in thrombosis therapy is also introduced. Last of all, a prospective discussion on the future development of nanotechnology for thrombosis therapy is highlighted.

Blood biomarkers for new-onset hypertension in midlife women: a nested case-control study

OBJECTIVE

Midlife in women is associated with an increase in prevalence of hypertension. Little is known on the risk factors of new-onset hypertension among middle-aged women.

METHODS

In this nested case-control study, 1,430 women aged 40 to 60 years with repeated physical examinations between 2009 and 2019 were recruited. Data included age, body mass index, blood pressure (BP), and a series of blood biomarkers. Participants with hypertension were divided into two case-control samples: 388 cases with episodic new-onset hypertension (ie, one normal BP at the first visit and one abnormal BP during follow-up) each with two age-matched controls (n = 776) and 151 cases with regular new-onset hypertension (ie, normal BP at the first two visits and abnormal BP at two or more follow-up visits) each with three age-matched controls (n = 453). Multivariable-adjusted logistic regression was used to analyze the data.

RESULTS

Our data showed very consistent results for episodic and regular new-onset hypertension, respectively, and verified known associations (odds ratio [95% confidence interval], per SD increase) with obesity (body mass index, 1.72 [1.49-1.98] and 1.81 [1.45-2.26]), inflammation (white blood cell count, 1.39 [1.23-1.58] and 1.38 [1.13-1.69]), and metabolic dysregulation (triglycerides, 1.25 [1.09-1.44] and 1.31 [1.08-1.58]; glucose, 1.46 [1.23-1.73] and 1.27 [1.05-1.54]) but, more surprisingly, also revealed positive associations with red blood cell count (1.27 [1.11-1.44] and 1.38 [1.14-1.68]), hemoglobin (1.18 [1.03-1.35] and 1.31 [1.05-1.64]), and platelet count (1.39 [1.20-1.61] and 1.33 [1.09-1.63]).

CONCLUSIONS

In addition to obesity and metabolic dysregulation, increased hemoglobin and counts of platelets, and red and white blood cells are associated with hypertension in this period. Future study may verify whether these associations are causal in nature and whether these variables are useful in risk stratification.

Platelet-Covered Nanocarriers for Targeted Delivery of Hirudin to Eliminate Thrombotic Complication in Tumor Therapy

Most patients are at high risk of thrombosis during cancer treatment. However, the major discrepancy in the therapeutic mechanisms and microenvironment between tumors and thrombosis makes it challenging for a panacea to treat cancer while being able to eliminate the risk of thrombosis. Herein, we developed a biomimetic MnOx/Ag₂S nanoflower platform with platelet membrane modification (MnOx@Ag₂S@hirudin@platelet membrane: MAHP) for the long-term release of anticoagulant drugs to treat thrombosis together with tumor therapy. This MAHP platform could achieve the targeted delivery of hirudin to the thrombus site and perform the controlled release under the irradiation of near-infrared light, demonstrating effective removal of the thrombus. Moreover, MAHP could inhibit tumor progression and prolong the survival time of mice with thromboembolic complications.

At the Heart of Eosinophilic Granulomatosis with Polyangiitis: into Cardiac and Vascular Involvement

PURPOSE OF REVIEW

To provide an overview of existing literature on pathogenetic and clinical aspects of cardiac and vascular involvement in eosinophilic granulomatosis with polyangiitis (EGPA).

RECENT FINDINGS

In EGPA, cardiac and vascular involvement are more common than previously thought. However, no international recommendations on the topic are available yet. Herein, we summarize the existing evidence on the topic and propose a diagnostic approach for cardiac involvement in EGPA. The prevalence of cardiovascular involvement in patients with EGPA varies greatly among published studies, ranging between 3.1-18.7% for occlusive arterial disease, 5.8-30% for venous thrombosis and 17-92% for heart involvement. Cardiac involvement in EGPA is associated with high mortality even though manifestations are heterogeneous. In principle, every anatomical structure of the heart can be involved, and EGPA-related heart disease may be completely asymptomatic at first. A careful diagnostic work-up for early detection and prompt treatment initiation is therefore required. While cardiac manifestations are more common in anti-neutrophil cytoplasmic antibodies (ANCA)-negative patients, arterial and venous thrombotic events are not linked to ANCA status but correlate closely with disease activity and accumulate at disease onset. Thrombotic events (mainly venous) are considerably more frequent in EGPA than in the general population contributing substantially to morbidity and highlighting the importance of developing specific prevention strategies for patients who are diagnosed with EGPA.

Platelet Redox Imbalance in Hypercholesterolemia: A Big Problem for a Small Cell

The imbalance between reactive oxygen species (ROS) synthesis and their scavenging by anti-oxidant defences is the common soil of many disorders, including hypercholesterolemia. Platelets, the smallest blood cells, are deeply involved in the pathophysiology of occlusive arterial thrombi associated with myocardial infarction and stroke. A great deal of evidence shows that both increased intraplatelet ROS synthesis and impaired ROS neutralization are implicated in the thrombotic process. Hypercholesterolemia is recognized as cause of atherosclerosis, cerebro- and cardiovascular disease, and, closely related to this, is the widespread acceptance that it strongly contributes to platelet hyperreactivity via direct oxidized LDL (oxLDL)-platelet membrane interaction via scavenger receptors such as CD36 and signaling pathways including Src family kinases (SFK), mitogen-activated protein kinases (MAPK), and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. In turn, activated platelets contribute to oxLDL generation, which ends up propagating platelet activation and thrombus formation through a mechanism mediated by oxidative stress. When evaluating the effect of lipid-lowering therapies on thrombogenesis, a large body of evidence shows that the effects of statins and proprotein convertase subtilisin/kexin type 9 inhibitors are not limited to the reduction of LDL-C but also to the down-regulation of platelet reactivity mainly by mechanisms sensitive to intracellular redox balance. In this review, we will focus on the role of oxidative stress-related mechanisms as a cause of platelet hyperreactivity and the pathophysiological link of the pleiotropism of lipid-lowering agents to the beneficial effects on platelet function.

The Sodium-Glucose Co-Transporter-2 (SGLT2) Inhibitors Reduce Platelet Activation and Thrombus Formation by Lowering NOX2-Related Oxidative Stress: A Pilot Study

Sodium−glucose co-transporter-2 inhibitors or gliflozins, the newest anti-hyperglycemic class, induce cardioprotective benefits in patients with type 2 diabetes (T2D). As platelet activation and oxidative stress play a key role in atherothrombotic-related complications, we hypothesized that gliflozins might modulate oxidative stress, platelet activation and thrombus formation. We performed an interventional open-label single-arm before-after study in 32 T2D patients on top of their ongoing metformin therapy. The population was divided into two groups: treatment with GLP-1 receptor agonists (GLP-1RA, Group A) and gliflozins (Group B). Oxidative stress, platelet activation and thrombus growth were assessed before and after 15 days of treatment. Compared to the baseline, gliflozins treatment significantly decreased sNOX2-dp (−45.2%, p < 0.001), H2O2 production (−53.4%, p < 0.001), TxB2 (−33.1%, p < 0.001), sP-selectin (−49.3%, p < 0.001) and sCD40L levels (−62.3%, p < 0.001) as well as thrombus formation (−32%, p < 0.001), whereas it potentiated anti-oxidant power (HBA, +30.8%, p < 0.001). Moreover, a significant difference in oxidative stress, platelet activation and thrombus formation across groups A and B was found. In addition, an in vitro study on stimulated platelets treated with gliflozins (10−30 μM) showed a reduction in oxidative stress, platelet activation and thrombus growth. Our results showed that gliflozins have antiplatelet and antithrombic activity related to an NOX2 down-regulation, suggesting a new mechanism responsible for cardiovascular protection.

Three-Dimensional Quantitative Structure and Activity Relationship of Flavones on Their Hypochlorite Scavenging Capacity

Flavonoids, a class of polyphenolic substances widely present in the plant realm, are considered as ideal hypochlorite scavengers. However, to our knowledge, little study has focused on the structure-activity relationship between flavonoids and hypochlorite scavenging capacity. Herein, we report for the first time the three-dimensional quantitative structure and activity relationship (3D-QSAR) combined with comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). Four models derived from CoMFA and CoMSIA with different combinations of descriptors were built and compared; the CoMFA model, which included both steric and electrostatic fields, showed great potential (R² = 0.989; Q² = 0.818) in predictive quality according to both internal and external validation criteria. Additionally, the average local ionization energy (ALIE), electrostatic potential (ESP), and orbital weighted dual descriptor (OWDD) were determined to identify the key structural moiety for scavenging capacity of flavonoids against hypochlorite. The computational results indicated that hypochlorous acid (HClO) serves as an electrophile undergoing electrophilic addition to the C6 carbon, which has the highest negative charge density, which are influenced by the functional groups on the flavones. The DFT calculated mechanism revealed the catalytic role of water of mono- and di-chlorination reactions, characterized by low activation barriers, and the involvement of neutral, instead of high-energy carbocation, intermediates.

Comparison Benefit between Hydrogen Peroxide and Adrenaline in Tonsillectomy: A Randomized Controlled Study

This study aimed to further evaluate the benefit of topical hemostasis agents in tonsillectomy. We compared the clinical effects of topical application between hydrogen peroxide and adrenaline in tonsillectomy. Overall, 60 patients (120 tonsils) were prospectively enrolled for tonsillectomy between February 2018 and December 2020. The patients were randomly assigned to either the hydrogen peroxide or adrenaline group. Then, tonsillectomy was performed using hydrogen peroxide as a hemostatic agent on the assigned side, while adrenaline was applied to the other side. All procedures were performed by a surgeon who was blinded to the randomization. The outcome measurements of operation time, intraoperative blood loss, postoperative pain, and hemorrhage events were analyzed. The intraoperative blood loss was significantly lower in the hydrogen peroxide group than in the adrenaline group (9.99 ± 4.51 mL vs. 13.87 ± 6.32 mL; p = 0.0). The median operation time was also significantly lower in the hydrogen peroxide group (8.02 ± 3.59 min vs. 9.22 ± 3.88 min; p = 0.019). Meanwhile, the visual analogue scale (VAS) scores were significantly higher in the hydrogen peroxide group (4.98 ± 1.94 vs. 4.27 ± 1.97; p = 0.001). The topical application of hydrogen peroxide as a hemostatic agent effectively decreases the operation time and intraoperative blood loss. Thus, hydrogen peroxide can be used as a routine hemostatic agent for bleeding control in tonsillectomy.

Platelet-leukocyte crosstalk in COVID-19: How might the reciprocal links between thrombotic events and inflammatory state affect treatment strategies and disease prognosis?

Platelet-leukocyte crosstalk is commonly manifested by reciprocal links between thrombosis and inflammation. Platelet thrombus acts as a reactive matrix that recruits leukocytes to the injury site where their massive accumulation, activation and migration promote thrombotic events while triggering inflammatory responses. As a life-threatening condition with the associations between inflammation and thrombosis, COVID-19 presents diffuse alveolar damage due to exaggerated macrophage activity and cytokine storms. These events, together with direct intracellular virus invasion lead to pulmonary vascular endothelialitis, cell membranes disruption, severe endothelial injury, and thrombosis. The developing pre-alveolar thrombus provides a hyper-reactive milieu that recruits circulating leukocytes to the injury site where their activation contributes to thrombus stabilization and thrombosis propagation, primarily through the formation of Neutrophil extracellular trap (NET). NET fragments can also circulate and deposit in further distance where they may disseminate intravascular thrombosis in severe cases of disease. Thrombi may also facilitate leukocytes migration into alveoli where their accumulation and activation exacerbate cytokine storms and tissue damage, further complicating the disease. Based on these mechanisms, whether an effective anti-inflammatory protocol can prevent thrombotic events, or on the other hand; efficient antiplatelet or anticoagulant regimens may be associated with reduced cytokine storms and tissue damage, is now of interests for several ongoing researches. Thus shedding more light on platelet-leukocyte crosstalk, the review presented here discusses the detailed mechanisms by which platelets may contribute to the pathogenesis of COVID-19, especially in severe cases where their interaction with leukocytes can intensify both inflammatory state and thrombosis in a reciprocal manner.

Antithrombotic Therapy by Regulating the ROS-Mediated Thrombosis Microenvironment and Specific Nonpharmaceutical Thrombolysis Using Prussian Blue Nanodroplets

In thrombotic diseases, the effects of reactive oxygen species (ROS)-mediated oxidative stress as a "perpetrator" in thrombosis must be resolved. Accordingly, an insufficient understanding of thrombus therapy prompted the authors to pursue a more comprehensive and efficient antithrombotic treatment strategy. A Prussian blue (PB)-based nanodroplet system (PB-PFP@PC) is designed using PB and perfluorinated pentane (PFP) in the core, and a targeting peptide (CREKA, Cys-Arg-Glu-Lys-Ala) is attached to poly(lactic-coglycolic acid) (PLGA) as the delivery carrier shell. Upon near-infrared (NIR) laser irradiation, PB and PFP jointly achieve an unprecedented dual strategy for drug-free thrombolysis: photothermal therapy (PTT) combined with optical droplet vaporization (ODV). PB, a nanoenzyme, also regulates the vascular microenvironment via its antioxidant activity to continuously scavenge abnormally elevated ROS and correspondingly reduce inflammatory factors in the thrombus site. This study provides a demonstration of not only the potential of ODV in thrombus therapy but also the mechanism underlying PTT thrombolysis due to thermal ablation-induced fibrin network structural damage. Moreover, PB catalyzes ROS to generate oxygen (O₂ ), which combines with the ODV effect, enhancing the ultrasound signal. Thus, regulation of the thrombosis microenvironment combined with specific nonpharmaceutical thrombolysis by PB nanodroplets provides a more comprehensive and efficient antithrombotic therapeutic strategy.

Mechanisms Underlying Dichotomous Procoagulant COAT Platelet Generation-A Conceptual Review Summarizing Current Knowledge

Procoagulant platelets are a subtype of activated platelets that sustains thrombin generation in order to consolidate the clot and stop bleeding. This aspect of platelet activation is gaining more and more recognition and interest. In fact, next to aggregating platelets, procoagulant platelets are key regulators of thrombus formation. Imbalance of both subpopulations can lead to undesired thrombotic or bleeding events. COAT platelets derive from a common pro-aggregatory phenotype in cells capable of accumulating enough cytosolic calcium to trigger specific pathways that mediate the loss of their aggregating properties and the development of new adhesive and procoagulant characteristics. Complex cascades of signaling events are involved and this may explain why an inter-individual variability exists in procoagulant potential. Nowadays, we know the key agonists and mediators underlying the generation of a procoagulant platelet response. However, we still lack insight into the actual mechanisms controlling this dichotomous pattern (i.e., procoagulant versus aggregating phenotype). In this review, we describe the phenotypic characteristics of procoagulant COAT platelets, we detail the current knowledge on the mechanisms of the procoagulant response, and discuss possible drivers of this dichotomous diversification, in particular addressing the impact of the platelet environment during in vivo thrombus formation.

Platelets in Fetal Growth Restriction: Role of Reactive Oxygen Species, Oxygen Metabolism, and Aggregation

Fetal growth restriction (FGR) is mainly caused by failure of the uteroplacental unit. The exact pathogenesis remains unclear. The cause is thought to be related to abnormal platelet activation, which may result in microthrombus formation in the small vessels of the placenta. Reactive oxygen species (ROS) may initiate the pathological process of platelet activation. This study aimed to evaluate selected platelet parameters in pregnancy complicated by FGR and relate them to the severity of hemodynamic abnormalities. A total of 135 women (pregnant with FGR, with an uncomplicated pregnancy, and non-pregnant) were enrolled to study different platelet parameters: count (PLT), mean volume (MPV), ROS levels, intracellular oxygen level, oxygen consumption, and aggregation indices. No abnormalities in PLT and MPV were found in the FGR group, although it revealed increased ROS levels in platelets, lower platelet oxygen consumption, and intraplatelet deprivation. Aggregation parameters were similar as in uncomplicated pregnancy. No significant relationships were observed between hemodynamic abnormalities and the studied parameters. Platelets in pregnancies complicated by FGR may reveal an impaired oxidative metabolism, which may, in turn, lead to oxidative stress and, consequently, to an impaired platelet function. This study adds to the understanding of the role of platelets in the etiology of FGR.

Combination of Colchicine and Ticagrelor Inhibits Carrageenan-Induced Thrombi in Mice

The formation of a thrombus is closely related to oxidative stress and inflammation. Colchicine is one of the most commonly prescribed medication for gout treatment, with anti-inflammation and antioxidative stress properties. Therefore, we speculated that it is possible for colchicine to treat thrombosis. In this study, we used carrageenan to induce thrombosis in BALB/c mice and fed mice with colchicine, ticagrelor, and their combination, respectively. We found colchicine inhibited carrageenan-induced thrombi in mouse tail, and the inhibition was enhanced by ticagrelor. In vitro, colchicine inhibited thrombin-induced retraction of human platelet clots. Mechanically, colchicine inhibited platelet activation by reducing the expression of platelet receptors, protease-activated receptor 4 (PAR4) and CD36, and inactivating of AKT and ERK1/2 pathways. Furthermore, in human umbilical vein endothelial cells (HUVECs), colchicine showed antioxidative stress effects through increasing protein expression of glutathione peroxidase-1 (GPx-1), and mRNA levels of forkhead box O3 (FOXO3a) and superoxide dismutase 2 (SOD2). In RAW264.7 cells, colchicine reduced LPS-enhanced inflammatory response through attenuating toll-like receptor 4 (TLR4) activation. In addition, colchicine reduced LPS or ox-LDL-induced monocyte adhesion to HUVECs by inhibiting intercellular adhesion molecule-1 (ICAM-1) and vascular adhesion molecule-1 (VCAM-1) levels. Taken together, our study demonstrates that colchicine exerts antithrombotic function by attenuating platelet activation and inhibiting oxidative stress and inflammation. We also provide a potential new strategy for clinical treatment.

Clotting Dysfunction in Sepsis: A Role for ROS and Potential for Therapeutic Intervention

Sepsis is regarded as one of the main causes of death among the critically ill. Pathogen infection results in a host-mediated pro-inflammatory response to fight infection; as part of this response, significant endogenous reactive oxygen (ROS) and nitrogen species (RNS) production occurs, instigated by a variety of sources, including activated inflammatory cells, such as neutrophils, platelets, and cells from the vascular endothelium. Inflammation can become an inappropriate self-sustaining and expansive process, resulting in sepsis. Patients with sepsis often exhibit loss of aspects of normal vascular homeostatic control, resulting in abnormal coagulation events and the development of disseminated intravascular coagulation. Diagnosis and treatment of sepsis remain a significant challenge for healthcare providers globally. Targeting the drivers of excessive oxidative/nitrosative stress using antioxidant treatments might be a therapeutic option. This review focuses on the association between excessive oxidative/nitrosative stress, a common feature in sepsis, and loss of homeostatic control at the level of the vasculature. The literature relating to potential antioxidants is also described.

Oxidative Stress and Endothelial Dysfunction in Sepsis and Acute Inflammation

Significance: Under homeostatic conditions, the endothelium dynamically regulates vascular barrier function, coagulation pathways, leukocyte adhesion, and vasomotor tone. During sepsis and acute inflammation, endothelial cells (ECs) undergo multiple phenotypic and functional modifications that are initially adaptive but eventually become harmful, leading to microvascular dysfunction and multiorgan failure. Critical Issues and Recent Advances: Sepsis unbalances the redox homeostasis toward a pro-oxidant state, characterized by an excess production of reactive oxygen species and reactive nitrogen species, mitochondrial dysfunction, and a breakdown of antioxidant systems. In return, oxidative stress (OS) alters multiple EC functions and promotes a proinflammatory, procoagulant, and proadhesive phenotype. The OS also induces glycocalyx deterioration, cell death, increased permeability, and impaired vasoreactivity. Thus, during sepsis, the ECs are both a significant source and one of the main targets of OS. Future Directions: This review aims at covering the current understanding of the role of OS in the endothelial adaptive or maladaptive multifaceted response to sepsis and to outline the therapeutic potential and issues of targeting OS and endothelial dysfunction during sepsis and septic shock. One of the many challenges in the management of sepsis is now based on the detection and correction of these anomalies of endothelial function.

Prothrombotic state associated with preeclampsia

PURPOSE OF REVIEW

Preeclampsia is a common complication of pregnancy and contributes significantly to maternal and fetal morbidity and mortality. A protective hypercoagulable state is often developed during late pregnancy and can evolve into a prothrombotic state in patients with preeclampsia. The underlying mechanism of this prothrombotic transition remains poorly understood. We discuss recent progress in understanding the pathophysiology of preeclampsia and associated prothrombotic state.

RECENT FINDINGS

The hypercoagulable state developed during pregnancy is initiated by placental factors and progresses into the prothrombotic state in preeclampsia when the placenta is subjected ischemic and oxidative injuries. The cause of the preeclampsia-induced prothrombotic state is multifactorial, involving not only placental factors but also maternal conditions, which include genetic predisposition, preexisting medical conditions, and conditions acquired during pregnancy. Endotheliopathy is the primary pathology of preeclampsia and contributes to the prothrombotic state by inducing the dysregulation of coagulation, platelets, and adhesive ligands.

SUMMARY

Patients with preeclampsia often develop a severe prothrombotic state that predisposes them to life-threatening thrombosis and thromboembolism during and after pregnancy. Early recognition and treatment of this prothrombotic state can improve maternal and infant outcomes of preeclampsia patients.

Hydrogen peroxide-responsive platelet membrane-coated nanoparticles for thrombus therapy

Occlusion of blood vessels caused by thrombi is the major pathogenesis of various catastrophic cardiovascular diseases. Thrombi can be prevented or treated by antithrombotic drugs. However, free antithrombotic drugs often have relatively low therapeutic efficacy due to a number of limitations such as short half-life, unexpected bleeding complications, low thrombus targeting capability, and negligible hydrogen peroxide (H2O2)-scavenging ability. Inspired by the abundance of H2O2 and the active thrombus-targeting property of platelets, a H2O2-responsive platelet membrane-cloaked argatroban-loaded polymeric nanoparticle (PNPArg) was developed for thrombus therapy. Poly(vanillyl alcohol-co-oxalate) (PVAX), a H2O2-degradable polymer, was synthesized to form an argatroban-loaded nanocore, which was further coated with platelet membrane. The PNPArg can effectively target the blood clots due to the thrombus-homing property of the cloaked platelet membrane, and subsequently exert combined H2O2-scavenging effect via the H2O2-degradable nanocarrier polymer and antithrombotic effect via argatroban, the released payload. The PNPArg effectively scavenged H2O2 and protected cells from H2O2-induced cellular injury in RAW 264.7 cells and HUVECs. The PNPArg rapidly targeted the thrombosed vessels and remarkably suppressed thrombus formation, and the levels of H2O2 and inflammatory cytokines in the ferric chloride-induced carotid arterial thrombosis mouse model. Safety assessment indicated good biocompatibility of the PNPArg. Taken together, the biomimetic PNPArg offers multiple functionalities including thrombus-targeting, antioxidation, and H2O2-stimulated antithrombotic action, thereby making it a promising therapeutic nanomedicine for thrombosis diseases.

Thrombolome and Its Emerging Role in Chronic Kidney Diseases

Patients with chronic kidney disease (CKD) are at an increased risk of thromboembolic complications, including myocardial infarction, stroke, deep vein thrombosis, and pulmonary embolism. These complications lead to increased mortality. Evidence points to the key role of CKD-associated dysbiosis and its effect via the generation of gut microbial metabolites in inducing the prothrombotic phenotype. This phenomenon is known as thrombolome, a panel of intestinal bacteria-derived uremic toxins that enhance thrombosis via increased tissue factor expression, platelet hyperactivity, microparticles release, and endothelial dysfunction. This review discusses the role of uremic toxins derived from gut-microbiota metabolism of dietary tryptophan (indoxyl sulfate (IS), indole-3-acetic acid (IAA), kynurenine (KYN)), phenylalanine/tyrosine (p-cresol sulfate (PCS), p-cresol glucuronide (PCG), phenylacetylglutamine (PAGln)) and choline/phosphatidylcholine (trimethylamine N-oxide (TMAO)) in spontaneously induced thrombosis. The increase in the generation of gut microbial uremic toxins, the activation of aryl hydrocarbon (AhRs) and platelet adrenergic (ARs) receptors, and the nuclear factor kappa B (NF-κB) signaling pathway can serve as potential targets during the prevention of thromboembolic events. They can also help create a new therapeutic approach in the CKD population.

NADPH Oxidases Are Required for Full Platelet Activation In Vitro and Thrombosis In Vivo but Dispensable for Plasma Coagulation and Hemostasis

OBJECTIVE

Using 3KO (triple NOX [NADPH oxidase] knockout) mice (ie, NOX1-/-/NOX2-/-/NOX4-/-), we aimed to clarify the role of this family of enzymes in the regulation of platelets in vitro and hemostasis in vivo. Approach and Results: 3KO mice displayed significantly reduced platelet superoxide radical generation, which was associated with impaired platelet aggregation, adhesion, and thrombus formation in response to the key agonists collagen and thrombin. A comparison with single-gene knockouts suggested that the phenotype of 3KO platelets is the combination of the effects of the genetic deletion of NOX1 and NOX2, while NOX4 does not show any significant function in platelet regulation. 3KO platelets displayed significantly higher levels of cGMP-a negative platelet regulator that activates PKG (protein kinase G). The inhibition of PKG substantially but only partially rescued the defective phenotype of 3KO platelets, which are responsive to both collagen and thrombin in the presence of the PKG inhibitors KT5823 or Rp-8-pCPT-cGMPs, but not in the presence of the NOS (NO synthase) inhibitor L-NG-monomethyl arginine. In vivo, triple NOX deficiency protected against ferric chloride-driven carotid artery thrombosis and experimental pulmonary embolism, while hemostasis tested in a tail-tip transection assay was not affected. Procoagulatory activity of platelets (ie, phosphatidylserine surface exposure) and the coagulation cascade in platelet-free plasma were normal.

CONCLUSIONS

This study indicates that inhibiting NOXs has strong antithrombotic effects partially caused by increased intracellular cGMP but spares hemostasis. NOXs are, therefore, pharmacotherapeutic targets to develop new antithrombotic drugs without bleeding side effects.

Brief High Oxygen Concentration Induces Oxidative Stress in Leukocytes and Platelets: A Randomized Cross-over Pilot Study in Healthy Male Volunteers

BACKGROUND

Supplemental oxygen is administered routinely in the clinical setting to relieve or prevent tissue hypoxia, but excessive exposure may induce oxidative damage or disrupt essential homeostatic functions. It is speculated that oxidative stress in leukocytes and platelets may contribute to vascular diseases by promoting inflammation and cell aggregation.

METHODS

In this pilot study 30 healthy male volunteers (18-65 years) were exposed to high oxygen concentration (non-rebreather mask, 8 L/min, 100% O2) and synthetic air (non-rebreather mask, 8 L/min, 21% O2) in a cross-over design for 20 min at a 3-week interval. Venous blood samples were obtained at baseline and 1, 3, and 6 h postintervention. Primary outcome was generation of reactive oxygen species in leukocytes as measured by the redox-sensitive fluorescent dye dihydrorhodamine 123. Additional outcomes were oxidative stress in platelets and platelet aggregation as measured by thromboelastography (ROTEM) and Multiplate analyses.

FINDINGS

High oxygen exposure induced oxidative stress in leukocytes as evidenced by significantly higher mean fluorescence intensity (MFI) compared with synthetic air at 3 h postintervention (47% higher, P = 0.015) and 6 h postintervention (37% higher, P = 0.133). Oxidative stress was also detectable in platelets (33% higher MFI in comparison with synthetic air at 6 h, P = 0.024; MFI 20% above baseline at 3 h, P  = 0.036; 37% above baseline at 6 h, P = 0.002). ROTEM analyses demonstrated reduced mean clotting time 1 h postintervention compared with baseline (-4%, P = 0.049), whereas there were no significant effects on other surrogate coagulation parameters.

CONCLUSION

Clinically relevant oxygen exposure induces oxidative stress in leukocytes and platelets, which may influence the immune and clotting functions of these cells.

N-acetylcysteine reduce the stress induced by cold storage of platelets: A potential way to extend shelf life of platelets

The room temperature storage used for platelets worldwide leads to platelet storage lesion (PSL) and risk of bacterial growth, limiting platelet shelf life and safety in transfusion. Thus, there is a need for an alternative storage method that can serve as effective temperature storage for platelet concentrates (PCs). In the previous investigation, we have shown that N-acetylcysteine (NAC) is a potential candidate for an additive solution to retain platelet characteristics during cold storage for up to 5 days. However, the study partially describes the efficacy and has drawbacks to address. Here, we used the apheresis platelet product with 50 mM NAC and stored up to 10 days under refrigerated condition (4 ± 1 °C). Stored platelet concentrates were analyzed for critical parameters such as platelet activation, annexin V binding, sialic acid, reactive oxygen species (ROS), neuraminidase activity, and in vivo efficacy using Prkdc^scid mice. Investigation observations revealed that PCs with NAC showed reduced platelet activation, annexin V binding, ROS production, and sialic acid levels. in vivo recovery of PCs showed similar recovery rates stored PCs irrespective of treatment or storage condition. However, on the tenth day after 24 h, recovery in room temperature stored concentrates was about 32 %, whereas in NAC treated refrigerated concentrates, it stands at 47 %. These observations indicate that NAC addition protects refrigerated concentrates during long-term storage retaining the platelet integrity. The study also suggests that extending PC storage beyond 10 days is practically accomplishable with efficacy similar to room temperature (RT) stored PCs.

Organ Care System Lung resulted in lower apoptosis and iNOS expression in donor lungs

Ischemia-reperfusion (IR) injury after lung transplantation is still today an important complication in up to 25% of patients. The Organ Care System (OCS) Lung, an advanced normothermic ex vivo lung perfusion system, was found to be effective in reducing primary graft dysfunction compared to standard organ care (SOC) but studies on tissue/molecular pathways that could explain these more effective clinical results are lacking. This observational longitudinal study aimed to investigate IR injury in 68 tissue specimens collected before and after reperfusion from 17 OCS and 17 SOC preserved donor lungs. Several tissue analyses including apoptosis evaluation and inducible nitric oxide synthase (iNOS) expression (by immunohistochemistry and real-time reverse transcriptase-polymerase chain reaction) were performed. Lower iNOS expression and apoptotic index were distinctive of OCS preserved tissues at pre- and post-reperfusion times, independently from potential confounding factors. Moreover, OCS recipients had lower acute cellular rejection at the first 6-month follow-up. In conclusion, IR injury, in terms of apoptosis and iNOS expression, was less frequent in OCS- than in SOC-preserved lungs, which could eventually explain a better clinical outcome. Further studies are needed to validate our data and determine the role of iNOS expression as a predictive biomarker of the complex IR injury mechanism.

Biomimetic fibrin-targeted and H2O2-responsive nanocarriers for thrombus therapy

Thrombosis is a principle cause of various life-threatening cardiovascular diseases. However, current antithrombotic treatments using drugs only offer limited efficacy due to short half-life, low targeting ability to the thrombus site, and unexpected bleeding complications. Taking into account of the biological characteristics of thrombus including upregulation of hydrogen peroxide (H₂O₂) and abundance of fibrin, we engineered a H₂O₂-responsive nanocarrier for thrombus-targeting delivery of an antithrombotic agent (i.e., tirofiban). The nanocarrier was composed of a drug-conjugated dextran nanocore and a red blood cell (RBC) membrane shell, and its surface was functionalized with a fibrin-targeting peptide, CREKA. Tirofiban was conjugated to dextran through a H₂O₂-cleavable phenylboronic ester linkage. The fibrin-targeting RBC membrane-cloaked dextran-tirofiban conjugate nanoparticles (i.e., T-RBC-DTC NPs) can scavenge H₂O₂ and provide controlled release of tirofiban to achieve site-specific antithrombotic effects. In RAW 264.7 cells and HUVECs, the T-RBC-DTC NPs effectively scavenged H₂O₂ and protected cells from H₂O₂-induced cytotoxicity. In the ferric chloride-induced carotid thrombosis mouse model, the T-RBC-DTC NPs efficiently accumulated at the injured carotid artery and exhibited significantly enhanced antithrombotic activity compared to free drug. The T-RBC-DTC NPs also exhibited good biocompatibility according to histology analysis. Overall, our results indicated that this bioengineered nanocarrier offers a promising therapeutic strategy for thrombotic disorders.

The effect of gamma irradiation on platelet redox state during storage

BACKGROUND

As a method with insignificant adverse effects on in vitro quality of platelet concentrates (PCs), gamma irradiation is applied to abrogate the risk of transfusion-associated graft-vs-host disease in vulnerable recipients. However, there is some evidence of lower posttransfusion responses and proteomic alterations in gamma-irradiated platelets (PLTs), which raises some questions about their quality, safety, and efficacy. Since reactive oxygen species (ROS) are considered as markers of PLT storage lesion (PSL), the study presented here investigated oxidant state in gamma-irradiated PCs.

STUDY DESIGN AND METHODS

PLT-rich plasma PC was split into two bags, one kept as control while other was subjected to gamma irradiation. Within 7 days of storage, the levels of intra-PLT superoxide, H₂ O₂ , mitochondrial ROS, P-selectin expression, and phosphatidylserine (PS) exposure were detected by flow cytometry while intracellular reduced glutathione (GSH), glucose concentration, and lactate dehydrogenase (LDH) activity were measured by enzymocolorimetric method.

RESULTS

GSH decreased, while ROS generation and LDH activity increased, during storage. Gamma irradiation significantly attenuated GSH whereas increased ROS generation in earlier and later stages of storage associated with either P-selectin or PS exposure increments.

CONCLUSION

Gamma irradiation can significantly increase cytosolic ROS generation in two distinct phases, one upon irradiation and another later in longer-stored PCs. While earlier ROS influx seems to be governed by direct effect of irradiation, the second phase of oxidant stress is presumably due to the storage-dependent PLT activation. Intriguingly, these observations were also in line with early P-selectin increments and increased PS exposure in longer-stored PLTs. Given the mutual link between ROS generation and PLT activation, further investigation is required to explore the effect of gamma irradiation on the induction of PSL.