Aspirin delimits platelet life span by proteasomal inhibition

Nanogold-coated stent facilitated non-invasive photothermal ablation of stent thrombosis and restoration of blood flow

In-stent restenosis (ISR) and stent thrombosis (ST) are the most serious complications of coronary angioplasty and stenting. Although the evolution of drug-eluting stents (DES) has significantly restricted the incidence of ISR, they are associated with an enhanced risk of ST. In the present study, we explore the photothermal ablation of a thrombus using a nano-enhanced thermogenic stent (NETS) as a modality for revascularization following ST. The photothermal activity of NETS, fabricated by coating bare metal stents with gold nanorods generating a thin plasmonic film of gold, was found to be effective in rarefying clots formed within the stent lumen in various in vitro assays including those under conditions mimicking blood flow. NETS implanted in the rat common carotid artery generated heat following exposure to a NIR-laser that led to effective restoration of blood flow within the occluded vessel in a model of ferric chloride-induced thrombosis. Our results present a proof-of-concept for a novel photothermal ablation approach by employing coated stents in the non-invasive management of ST.

Aspirin 15cH has Different Effects on Morphology and Function of Lipopolysaccharide-Challenged RAW 264.7 Macrophages In Vitro Compared to a Pharmacological Dose of Aspirin

INTRODUCTION

 Aspirin is one of the most commonly used drugs worldwide. It is known to present antipyretic, anti-inflammatory and anti-thrombotic actions, making it extremely useful in a wide range of clinical contexts. Interestingly, homeopathically prepared Aspirin 15cH has been found to have a pro-thrombotic effect in rats, raising the hypothesis that Aspirin 15cH could also modulate the activity of inflammatory cells in different pathological processes.

OBJECTIVE

 Our objective was to assess what effect Aspirin 15cH has on RAW 264.7 macrophages in vitro.

METHODS

 The effects of Aspirin 15cH on biochemical and morphological activities of lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages were evaluated. These effects were compared with unchallenged macrophages (negative control), untreated LPS-stimulated macrophages, macrophages treated with succussed water (vehicle control), or aspirin 200 µg/mL (pharmacological inhibitor of LPS activity). Cell morphology (adhered cell area and cytoskeleton arrangements), cell viability, toll-like receptor-4 (TLR-4) expression, and the production of nitric oxide, cytokines and intracellular reactive oxygen species were assessed.

RESULTS

 Aspirin 15cH reduced the number of cells expressing TLR-4 on the surface (p = 0.03) and induced a "columnar" morphology of macrophage pseudopods, indicating changes in cytoskeleton arrangement. When cells were treated with both Aspirin 15cH and LPS, cell morphology became heterogeneous, suggesting that sub-populations of cells had differing sensitivities to LPS or Aspirin 15cH. Exposure of the cells to LPS alone, succussed water or aspirin 200 µg/mL produced effects consistent with the literature.

CONCLUSION

 Aspirin 15cH, aspirin 200 µg/mL, LPS and succussed water appear to act as independent stimuli able to induce different patterns of macrophage response. Aspirin 15cH induced changes suggestive of M2 polarization of the macrophages (i.e., toward a wound healing or tissue repair, rather than inflammatory, phenotype). These preliminary findings need to be confirmed in further specific studies.

Aspirin and Infection: A Narrative Review

Acetylsalicylic acid (ASA) is one of the most commonly used drugs in the world. It derives from the extract of white willow bark, whose therapeutic potential was known in Egypt since 1534 BC. ASA’s pharmacological effects are historically considered secondary to its anti-inflammatory, platelet-inhibiting properties; however, human studies demonstrating a pro-inflammatory effect of ASA exist. It is likely that we are aware of only part of ASA’s mechanisms of action; moreover, the clinical effect is largely dependent on dosages. During the past few decades, evidence of the anti-infective properties of ASA has emerged. We performed a review of such research in order to provide a comprehensive overview of ASA and viral, bacterial, fungal and parasitic infections, as well as ASA’s antibiofilm properties.

The Role of Oxidative and Nitrosative Stress of Silver Nanoparticles in Human Parasitic Helminth Brugia malayi: A Mechanistic Insight

PURPOSE

Silver nanoparticles (AgNPs) mediated apoptosis is well-known but its rationale is yet to be elucidated. This study explored the mechanistic underpinning of the apoptosis in the Brugia malayi parasitic model.

METHOD

Silver nanoparticles were synthesized and tested against B. malayi microfilariae (Mf) to explore the role of oxidative and nitrosative stress in its apoptotic effect.

RESULTS

AgNPs caused significant decrease in reduced glutathione (GSH) level and increase in both protein carbonylation and nitric oxide (NO) level indicating oxidative as well as nitrosative stress. Both GSH and nitric oxide synthase (NOS) inhibitors exhibited marked reversal. Nanoparticles and NO-donor in combination but not the NO-donor alone showed significant antiparasitic effect implying the requisite of combined oxidative and nitrosative stress to induce apoptosis. Synthetically prepared peroxynitrite from NaNO₂ to H₂O₂ showed marked antiparasitic effect in very low dose which could be achieved neither by NaNO₂ or H₂O₂ alone. GSH reversed the effect of peroxynitrite similar to its specific inhibitor, acetaminophen. GSH also reversed the plummet in mitochondrial oxygen consumption by AgNPs.

CONCLUSION

We conclude that apoptosis by AgNPs is possibly mediated through peroxynitrite dependent depletion of GSH; this provides a significant insight into the pharmacological as well as toxicological impact of AgNPs.

A Comparison of Coagulation Function in Patients Receiving Aspirin and Cefoperazone-Sulbactam With and Without Vitamin K1: A Retrospective, Observational Study

PURPOSE

The study objective was to explore whether prophylaxis with vitamin K₁ improves abnormal coagulation function-associated cefoperazone-sulbactam in patients treated in the long term with low-dose aspirin.

METHODS

This retrospective, observational study assessed patients treated with long-term low-dose aspirin in a naval military hospital in China from 2004 to 2018, including all patients treated concurrently with cefoperazone-sulbactam with or without vitamin K₁. Differences in the coagulation index were analyzed statistically before and after receipt of cefoperazone-sulbactam.

FINDINGS

The cohort included 227 patients. After cefoperazone-sulbactam treatment, the mean (SD) prothrombin time (PT) was 14.07 (3.07) seconds, activated partial thromboplastin time (aPTT) was 35.15 (4.78) seconds, and international normalized ratio (INR) was 1.49 (0.49) in the cefoperazone-sulbactam group, which was significantly higher than the PT of 11.55 (1.29), aPTT of 31.37 (2.20), and INR of 1.12 (0.35) before cefoperazone-sulbactam treatment. No significant difference was in the cefoperazone-sulbactam plus vitamin K₁ group. In addition, no significant difference was found in the thrombin time or fibrinogen level between before and after cefoperazone-sulbactam treatment in both groups. The mean (SD) platelet counts of the 2 groups were 197.34 (71.82) × 10⁹/L and 187.75 (72.66) × 1 0⁹/L after cefoperazone-sulbactam treatment, respectively, which was significantly lower than 231.77 (77.05) × 10⁹/L and 232.08 (84.48) × 10⁹/L before cefoperazone-sulbactam treatment. There were greater proportions of coagulation disorders (prolongation of PT, aPTT, INR, and bleeding) after cefoperazone-sulbactam treatment in the cefoperazone-sulbactam group compared with that in the cefoperazone-sulbactam plus vitamin K₁ group.

IMPLICATIONS

Results indicate that, after adding cefoperazone-sulbactam to the regimens of patients receiving long-term low-dose aspirin, therapy contributed to remarkable increase in abnormal coagulation function and coagulation disorders. Prophylaxis with vitamin K₁ decreased the risk of these abnormalities in blood coagulation parameters associated with cefoperazone-sulbactam in patients taking long-term aspirin.

Role of Glutathione in Chalcone Derivative Induced Apoptosis of Brugia malayi and its Possible Therapeutic Implication

PURPOSE

Oxidative stress is an essential component of innate response against microbes. The oxidative impact has a very subtle connection with apoptosis. Our previous work indicated presumptive evidence of apoptosis by the chalcone derivatives against the human lymphatic filarial parasite. Evidence suggests the involvement of glutathione-S-transferase (GST) in the mechanism of action of chalcone drugs. In the present study, we explored the implications of redox status in apoptosis of the parasite by this drug.

RESULTS

Treatment with the representative drug, 4t, significantly decreased GSH level and increased GST activity in the Brugia malayi microfilariae (Mf) in comparison to Mf without 4t treatment. Drug-induced loss of motility of the parasites was reversed by the treatment with GSH (41%) and NAC (19%). A significant fall in rGST activity was observed due to drug addition, which could be reversed by the addition of GSH co-substrate, but not with the re-addition of rGST, indicating a vital role of GSH. In silico study demonstrated a favorable drug-GST enzyme interaction. Oxidative stress was reflected by increased protein carbonylation and intracellular reactive oxygen species level, in the drug-treated parasite. Mitochondrial oxygen consumption was reduced by the drug, which was reversed on the addition of GSH. Mitochondrial dysfunction was confirmed by MTT and cytochrome c assay. Apoptosis was confirmed by the inhibition in PARP activity.

CONCLUSION

We conclude that the depletion of GSH by chalcone with concomitant mitochondrial dysfunction revealed a novel rationale of apoptosis in the parasite. Such a mechanism might have wide therapeutic implications.

Autoinducer N-(3-oxododecanoyl)-l-homoserine lactone induces calcium and reactive oxygen species-mediated mitochondrial damage and apoptosis in blood platelets

Acylated homoserine lactones (AHL) such as N-(3-oxododecanoyl)-l-homoserine lactone (3-oxo-C₁₂ HSL) and N-butyryl-l-homoserine lactone (C₄ HSL) are the most common autoinducer molecules in Pseudomonas aeruginosa. These AHL molecules not only regulate the expression of virulence factors but also have been shown to interfere with the host cell and modulate its functions. Recently, we reported that 3-oxo-C₁₂ HSL but not C₄ HSL causes cytosolic Ca²⁺ rise and ROS production in platelets. In this study, we examined the potential of AHLs to induce apoptosis in the human blood platelet. Our result showed that 3-oxo-C₁₂ HSL but not C₄ HSL causes phosphatidylserine (PS) exposure, mitochondrial dysfunction (mitochondrial transmembrane potential loss, and mitochondrial permeability transition pore (mPTP) formation). Besides, 3-oxo-C₁₂ HSL also inhibited thrombin-induced platelet aggregation and clot retraction. The pretreatment of an intracellular calcium chelator BAPTA-AM or ROS inhibitor (DPI) significantly attenuated the 3-oxo-C₁₂ HSL induced apoptotic characters such as PS exposure and mitochondrial dysfunctions. These data, including our previous findings, confirmed that 3-oxo-C₁₂ HSL induced intracellular Ca²⁺ mediated ROS production results in the activation and subsequent induction of apoptotic features in platelets. Our results demonstrated that the 3-oxo-C₁₂ HSL modulates the functions of platelets that may cause severe thrombotic complications in P. aeruginosa infected individuals.

Pro-apoptotic properties and mitochondrial functionality in platelet-like-particles generated from low Aspirin-incubated Meg-01 cells

Long-term therapy with low Aspirin (ASA) dose is basis to prevent thrombotic acute events. However, the anti-platelet mechanisms of ASA remain not completely known. The aim was to analyze if in vitro exposure of human megakaryocytes to low ASA concentration may alter the apoptotic features of the newly formed platelets. Cultured Meg-01 cells, a human megakaryoblastic cell line, were stimulated to form platelets with 10 nmol/L phorbol 12-myristate-13-acetate (PMA) in the presence and absence of ASA (0.33 mmol/L). Results revealed that platelet-like particles (PLPs) derived from ASA-exposed Meg-01 cells, showed higher content of pro-apoptotic proteins Bax and Bak than PLPs from non-ASA incubated Meg-01 cells. It was accompanied of reduced cytochrome C oxidase activity and higher mitochondrial content of PTEN-induced putative kinase-1 in PLPs from ASA-incubated Meg-01 cells. However, only after calcium ionophore A23187 stimulation, caspase-3 activity, the cytosolic cytochrome C content, and reduction of mitochondrial membrane potential were higher in PLPs from ASA-incubated megakaryocytes than in those from Meg-01 without ASA. Nitric oxide synthase 3 content was higher in PLPs from ASA-exposed Meg-01 cells than in PLPs from non-ASA incubated Meg-01 cells. The L-arginine antagonist, NG-Nitro-L-arginine Methyl Ester, reduced caspase-3 activity in A23187-stimulated PLPs generated from ASA-incubated Meg-01 cells. As conclusions exposure of megakaryocyte to ASA promotes that the newly generated PLPs have, under stimulating condition, higher sensitivity to go into apoptosis than those PLPs generated from Meg-01 cells without ASA. It could be associated with differences in mitochondrial functionality and NO formation.

The role of bone marrow-derived cells in venous thromboembolism

Venous thrombosis is a life-threatening condition with high morbidity and mortality. Abnormal functioning of different cells in the blood is an integral part of its pathogenesis. In this review, we describe the contribution of bone marrow-derived cells to the development of this debilitating disease. We present both epidemiological and clinical data demonstrating involvement of various cell types in venous thrombosis, and discuss potential mechanisms underlying these effects. Modern concepts including recently discovered new paradigms in thrombosis, such as neutrophil extracellular traps, mast cells, and polyphosphate, are summarized.

Not all (N)SAID and done: Effects of nonsteroidal anti-inflammatory drugs and paracetamol intake on platelets

Platelets are key mediators of hemostasis and thrombosis and can be inhibited by nonsteroidal anti-inflammatory drugs (NSAIDs). As a result, platelet donors are temporarily deferred from donating if they have recently taken NSAIDs such as aspirin or ibuprofen. Despite these measures, a proportion of platelet donations show exposure to these drugs; however, little is known about the effect of NSAIDs and their metabolites on platelet quality in vivo and during storage. In this review, the effect of NSAIDs on platelet function is summarized, with a focus on the widely consumed over-the-counter (OTC) medications aspirin, ibuprofen, and the non-NSAID paracetamol. Aspirin and ibuprofen have well-defined antiplatelet effects. In comparison, studies regarding the effect of paracetamol on platelets report variable findings. The timing and order of NSAID intake is important, as concurrent NSAID use can inhibit or potentiate platelet activation depending on the drug taken. NSAID deferral periods and maximum platelet shelf-life is set by each country and are revised regularly. Reduced donor deferral periods and longer platelet storage times may affect the quality of platelet products, and it is therefore important to identify the possible impact of NSAID intake on platelet quality before and after storage.

Hemin-induced platelet activation and ferroptosis is mediated through ROS-driven proteasomal activity and inflammasome activation: Protection by Melatonin

Reactive oxygen species (ROS) are capable of inducing cell death or apoptosis. Recently, we demonstrated that lipid-ROS can mediate ferroptosis and activation of human platelets. Ferroptosis is an intracellular iron-mediated cell death, distinct from classical apoptosis and necrosis, which is mediated through the accumulation of ROS, lipid peroxides and depletion of cellular GSH. Lately, we demonstrated that hemoglobin degradation product hemin induces ferroptosis in platelets via ROS and lipid peroxidation. In this study, we demonstrate that hemin-induced ferroptosis in platelets is mediated through ROS-driven proteasome activity and inflammasome activation, which were mitigated by Melatonin (MLT). Although inflammasome activation is linked with pyroptosis, it is still not clear whether ferroptosis is associated with inflammasome activation. Our study for the first time demonstrates an association of platelet activation/ferroptosis with proteasome activity and inflammasome activation. Although, high-throughput screening has recognized ferrostatin-1 (Fer-1) and liproxstatin-1 (Lip-1) as potent ferroptosis inhibitors, having an endogenous antioxidant such as MLT as ferroptosis inhibitor is of high interest. MLT is a well-known chronobiotic hormone that regulates the circadian rhythms in vertebrates. It also exhibits potent antioxidant and ROS quenching capabilities. MLT can regulate fundamental cellular functions by exhibiting cytoprotective, oncostatic, antiaging, anti-venom, and immunomodulatory activities. The ROS scavenging capacity of MLT is key for its cytoprotective and anti-apoptotic properties. Considering the anti-ferroptotic and anti-apoptotic potentials of MLT, it could be a promising clinical application to treat hemolytic, thrombotic and thrombocytopenic conditions. Therefore, we propose MLT as a pharmacological and therapeutic agent to inhibit ferroptosis and platelet activation.

Predictors of high on-aspirin platelet reactivity in elderly patients with coronary artery disease

Objectives

Previous studies have illustrated the link between high on-aspirin platelet reactivity (HAPR) with increasing thrombotic risks. The aim of our study was to investigate relative risk factors of HAPR in elderly patients with coronary artery disease.

Methods

Elderly, hospitalized coronary artery disease patients on regular aspirin treatment were enrolled from January 2014 to September 2016. Medical records of each patient were collected, including demographic information, cardiovascular risk factors, concomitant drugs and routine biological parameters. Arachidonic acid (AA, 0.5 mg/mL) and adenosine diphosphate (ADP, 5 µmol/L) induced platelet aggregation were measured via light transmission assay (LTA) to evaluate antiplatelet responses, referred as LTA–AA and LTA–ADP.

Results

A total of 275 elderly patients were included, with mean age of 77.2±8.1 years, and males accounted for 81.8%. HAPR was defined as LTA–AA in the upper quartile of the enrolled population. HAPR patients tended to have lower renal function (P=0.052). Higher serum uric acid (SUA) level, as well as lower platelet count, hemoglobin and hematocrit were observed in HAPR patients, with a higher proportion of diuretics use (P<0.05). Multivariate analysis revealed that SUA (OR: 1.004, 95% CI: 1.000–1.007, P=0.048), platelet count (OR: 0.994, 95% CI: 0.989–1.000, P=0.045), hematocrit (OR: 0.921, 95% CI: 0.864–0.981, P=0.011) and concomitant P2Y12 receptor inhibitors use (OR: 1.965, 95% CI: 1.075–3.592, P=0.028) were correlated with HAPR. Spearman’s correlation analysis demonstrated an inverse association of LTA–AA with hematocrit (r=−0.234, P<0.001), hemoglobin (r=−0.209, P<0.001) and estimated glomerular filtration rate (r=−0.132, P=0.031).

Conclusion

SUA, platelet count, hematocrit and P2Y12 receptor inhibitors use were independently correlated with HAPR. These parameters might provide novel therapeutic targets for optimizing antiplatelet therapy.

Acetylsalicylic acid differentially limits the activation and expression of cell death markers in human platelets exposed to Staphylococcus aureus strains

Beyond their hemostatic functions, platelets alter their inflammatory response according to the bacterial stimulus. Staphylococcus aureus is associated with exacerbated inflammation and thrombocytopenia, which is associated with poor prognosis during sepsis. Acetylsalicylic acid and statins prevent platelet aggregation and decrease the mortality rate during sepsis. Therefore, we assessed whether these two molecules could reduce in vitro platelet activation and the inflammatory response to S. aureus. Platelets were exposed to clinical strains of S. aureus in the presence or absence of acetylsalicylic acid or fluvastatin. Platelet activation, aggregation, and release of soluble sCD62P, sCD40 Ligand, RANTES and GROα were assessed. Platelet cell death was evaluated by analyzing the mitochondrial membrane potential, phosphatidylserine exposure, platelet microparticle release and caspase-3 activation. All S. aureus strains induced platelet activation but not aggregation and decreased the platelet count, the expression of cell death markers and the release of RANTES and GROα. Acetylsalicylic acid but not fluvastatin limited platelet activation and inflammatory factor release and restored the platelet count by protecting platelets from Staphylococcus-induced expression of cell death markers. This study demonstrates that acetylsalicylic acid limits S. aureus-induced effects on platelets by reducing cell death, revealing new strategies to reduce the platelet contribution to bacteremia-associated inflammation.

Adverse Effects of Subchronic Dose of Aspirin on Reproductive Profile of Male Rats

Aspirin (acetylsalicylic acid) is widely used for cardiovascular prophylaxis and as anti-inflammatory pharmaceutical. An investigation was carried out to evaluate the influence of subchronic dose of aspirin on reproductive profile of male rats, if any. Experimental animals were divided into three groups: control and aspirin subchronic dose of 12.5 mg/kg for 30 days and 60 days, respectively, while alterations in sperm dynamics, testicular histopathological and planimetric investigations, body and organs weights, lipid profiles, and hematology were performed as per aimed objectives. Subchronic dose of aspirin reduced sperm density, count, and mobility in cauda epididymis and testis; histopathology and developing primary spermatogonial cells (primary spermatogonia, secondary spermatogonia, and mature spermatocyte) count were also significantly decreased in rats. Hematological investigations revealed hemopoietic abnormalities in 60-day-treated animals along with dysfunctions in hepatic and renal functions. The findings of the present study revealed that administration with subchronic dose of aspirin to male rats resulted in altered reproductive profiles and serum biochemistry.

Unconjugated Bilirubin exerts Pro-Apoptotic Effect on Platelets via p38-MAPK activation

Thrombocytopenia is one of the most frequently observed secondary complications in many pathological conditions including liver diseases, where hyperbilirubinemia is very common. The present study sought to find the cause of thrombocytopenia in unconjugated hyperbilirubinemic conditions. Unconjugated bilirubin (UCB), an end-product of heme catabolism, is known to have pro-oxidative and cytotoxic effects at high serum concentration. We investigated the molecular mechanism underlying the pro-apoptotic effect of UCB on human platelets in vitro, and followed it up with studies in phenylhydrazine-induced hyperbilirubinemic rat model and hyperbilirubinemic human subjects. UCB is indeed found to significantly induce platelet apoptotic events including elevated endogenous reactive oxygen species generation, mitochondrial membrane depolarization, increased intracellular calcium levels, cardiolipin peroxidation and phosphatidylserine externalization (p < 0.001) as evident by FACS analysis. The immunoblots show the elevated levels of cytosolic cytochrome c and caspase activation in UCB-treated platelets. Further, UCB is found to induce mitochondrial ROS generation leading to p38 activation, followed by downstream activation of p53, ultimately resulting in altered expression of Bcl-2 and Bax proteins as evident from immunoblotting. All these parameters conclude that elevated unconjugated bilirubin causes thrombocytopenia by stimulating platelet apoptosis via mitochondrial ROS-induced p38 and p53 activation.