Effect of Ticagrelor on Reducing the Risk of Gram-Positive Infections in Patients With Acute Coronary Syndrome

The role of platelet P2Y12 receptors in inflammation

Inflammation is a complex pathophysiological process underlying many clinical conditions. Platelets contribute to the thrombo-inflammatory response. Platelet P2Y12 receptors amplify platelet activation, potentiating platelet aggregation, degranulation and shape change. The contents of platelet alpha granules, in particular, act directly on leucocytes, including mediating platelet-leucocyte aggregation and activation via platelet P-selectin. Much evidence for the role of platelet P2Y12 receptors in inflammation comes from studies using antagonists of these receptors, such as the thienopyridines clopidogrel and prasugrel, and the cyclopentyltriazolopyrimidine ticagrelor, in animal and human experimental models. These suggest that antagonism of P2Y12 receptors decreases markers of inflammation with some evidence that this reduces incidence of adverse clinical sequelae during inflammatory conditions. Interpretation is complicated by pleiotropic effects such as those of the thienopyridines on circulating leucocyte numbers and of ticagrelor on adenosine reuptake. The available evidence suggests that P2Y12 receptors are prominent mediators of inflammation and P2Y12 receptor antagonism as a potentially powerful strategy in a broad range of inflammatory conditions. LINKED ARTICLES: This article is part of a themed issue on Platelet purinergic receptor and non-thrombotic disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.4/issuetoc.

Endothelial ADAM10 utilization defines a molecular pathway of vascular injury in mice with bacterial sepsis

The endothelium plays a critical role in the host response to infection and has been a focus of investigation in sepsis. While it is appreciated that intravascular thrombus formation, severe inflammation, and loss of endothelial integrity impair tissue oxygenation during sepsis, the precise molecular mechanisms that lead to endothelial injury remain poorly understood. We demonstrate here that endothelial ADAM10 was essential for the pathogenesis of Staphylococcus aureus sepsis, contributing to α-toxin-mediated (Hla-mediated) microvascular thrombus formation and lethality. As ADAM10 is essential for endothelial development and homeostasis, we examined whether other major human sepsis pathogens also rely on ADAM10-dependent pathways in pathogenesis. Mice harboring an endothelium-specific knockout of ADAM10 were protected against lethal Pseudomonas aeruginosa and Streptococcus pneumoniae sepsis, yet remained fully susceptible to group B streptococci and Candida albicans sepsis. These studies illustrate a previously unknown role for ADAM10 in sepsis-associated endothelial injury and suggest that understanding pathogen-specific divergent host pathways in sepsis may enable more precise targeting of disease.

Bioactive surface coating for preventing mechanical heart valve thrombosis

BACKGROUND

Prosthetic heart valves are the only treatment for most patients with severe valvular heart disease. Mechanical valves, made of metallic components, are the most long-lasting type of replacement valves. However, they are prone to thrombosis and require permanent anticoagulation and monitoring, which leads to higher risk of bleeding and impacts the patient's quality of life.

OBJECTIVES

To develop a bioactive coating for mechanical valves with the aim to prevent thrombosis and improve patient outcomes.

METHODS

We used a catechol-based approach to produce a drug-releasing multilayer coating adherent to mechanical valves. The hemodynamic performance of coated Open Pivot valves was verified in a heart model tester, and coating durability in the long term was assessed in a durability tester producing accelerated cardiac cycles. Coating antithrombotic activity was evaluated in vitro with human plasma or whole blood under static and flow conditions and in vivo after surgical valve implantation in a pig's thoracic aorta.

RESULTS

We developed an antithrombotic coating consisting of ticagrelor- and minocycline-releasing cross-linked nanogels covalently linked to polyethylene glycol. We demonstrated the hydrodynamic performance, durability, and hemocompatibility of coated valves. The coating did not increase the contact phase activation of coagulation, and it prevented plasma protein adsorption, platelet adhesion, and thrombus formation. Implantation of coated valves in nonanticoagulated pigs for 1 month efficiently reduced valve thrombosis compared with noncoated valves.

CONCLUSION

Our coating efficiently inhibited mechanical valve thrombosis, which might solve the issues of anticoagulant use in patients and the number of revision surgeries due to valve thrombosis despite anticoagulation.

Management of patients on antithrombotic therapy with severe infections: a joint clinical consensus statement of the ESC Working Group on Thrombosis, the ESC Working Group on Atherosclerosis and Vascular Biology, and the International Society on Thrombosis and Haemostasis

Patients with severe infections and a pre-existing indication for antithrombotic therapy, i.e. antiplatelet agents, anticoagulant drugs, or their combinations, require integrated clinical counselling among coagulation, infectious disease, and cardiology specialists, due to sepsis-induced coagulopathy that frequently occurs. Bacterial and viral pathogens constitute an increasing threat to global public health, especially for patients with ongoing antithrombotic treatment who have a high risk of thrombotic recurrences and high susceptibility to severe infections with increased morbidity and mortality. Similarly, sepsis survivors are at increased risk for major vascular events. Coagulopathy, which often complicates severe infections, is associated with a high mortality and obligates clinicians to adjust antithrombotic drug type and dosing to avoid bleeding while preventing thrombotic complications. This clinical consensus statement reviews the best available evidence to provide expert opinion and statements on the management of patients hospitalized for severe bacterial or viral infections with a pre-existing indication for antithrombotic therapy (single or combined), in whom sepsis-induced coagulopathy is often observed. Balancing the risk of thrombosis and bleeding in these patients and preventing infections with vaccines, if available, are crucial to prevent events or improve outcomes and prognosis.

The Role of Platelets in Infective Endocarditis

Over the last decade, the incidence of infective endocarditis (IE) has increased, with a change in the frequency of causative bacteria. Early evidence has substantially demonstrated the crucial role of bacterial interaction with human platelets, with no clear mechanistic characterization in the pathogenesis of IE. The pathogenesis of endocarditis is so complex and atypical that it is still unclear how and why certain bacterial species will induce the formation of vegetation. In this review, we will analyze the key role of platelets in the physiopathology of endocarditis and in the formation of vegetation, depending on the bacterial species. We provide a comprehensive outline of the involvement of platelets in the host immune response, investigate the latest developments in platelet therapy, and discuss prospective research avenues for solving the mechanistic enigma of bacteria-platelet interaction for preventive and curative medicine.

Non-Antimicrobial Adjuvant Therapy Using Ticagrelor Reduced Biofilm-Related Staphylococcus aureus Prosthetic Joint Infection

Background: Prosthetic joint infection (PJI), frequently caused by Staphylococcus aureus, leads to a significant arthroplasty failure rate. Biofilm is a crucial virulence factor of S. aureus that is intrinsic to the pathogenesis of PJI. Biofilm-related infections are recalcitrant to antibiotic treatment. Surgical and antibiotic therapy could be combined with non-antibacterial adjuvants to improve overall treatment success. Ticagrelor, a P2Y12 receptor inhibitor antiplatelet drug, is known to have anti-staphylococcal antibacterial and antibiofilm activity. However, the molecular mechanism for ticagrelor’s antibiofilm activity and its efficacy in the treatment of S. aureus PJI are unknown.

Methods: To study the in vitro antibacterial and antibiofilm activity of ticagrelor, broth microdilution and crystal violet staining method were used. Ticagrelor’s effect on the expression of S. aureus biofilm genes (icaA, icaD, ebps, fib, eno, and agr) was studied using the relative quantification method. To test ticagrelor’s in vivo efficacy to treat S. aureus PJI, mice were randomized into five groups (n = 8/group): infected femoral implants treated with ticagrelor alone; infected implants treated with cefazolin alone; infected implants treated with ticagrelor and cefazolin; infected implants treated with phosphate buffer solution (PBS)-positive controls, and sterile implants-negative controls. Ticagrelor was administered orally from day 4 to day 7 post-surgery, while cefazolin was injected intravenously on day 7.

Results: Ticagrelor, alone and with selected antibiotics, showed in vitro antibacterial and antibiofilm activity against S. aureus. Strain-specific downregulation of biofilm-related genes, fib, icaD, ebps, and eno, was shown. In an animal model of biofilm-related S. aureus PJI, ticagrelor alone and combined with cefazolin significantly reduced bacterial concentrations on the implants compared with the positive control group. Ticagrelor significantly reduced bacterial dissemination to periprosthetic tissue compared with the positive controls.

Conclusion: Ticagrelor adjuvant therapy reduced S. aureus PJI in an animal model. However, this study is very preliminary to make a conclusion on the clinical implication of the findings. Based on the current results, more studies are recommended to better understand its implication.

Antiplatelet Therapy in Staphylococcus aureus Bacteremia: No Time Like the Past?

In this invited commentary, we reflect on the accompanying study by A. R. Caffrey, H. J. Appaneal, K. L. LaPlante, V. V. Lopes, et al. (Antimicrob Agents Chemother 66:e02117-21, 2022, https://doi.org/10.1128/aac.02117-21), which analyzed the impact of clopidogrel use on clinical outcomes in Staphylococcus aureus bacteremia.

Aspirin or Ticagrelor in Staphylococcus aureus Infective Endocarditis: Where Do We Stand?

Infective endocarditis is a challenging disease with a high mortality and morbidity rate. Antibiotic prophylaxis is currently recommended in high-risk infective endocarditis patients. However, the use of antibiotics faces the challenge of a low efficacy and contributes further to the emerging infection rate by antibiotic-resistant strains, emphasizing the need for new therapeutic strategies. Platelets are essential in the initial phase of infective endocarditis, acting as first-line immune responders. During the first phase of disease, bacteria can interact with platelets and counteract platelet antimicrobial activities. Mechanistic in vitro and animal studies on the effect of aspirin on bacteria-platelet interactions and the prevention of vegetation development showed promising results. However, data from clinical studies on the outcome of infective endocarditis patients who were receiving medically indicated aspirin therapy remain controversial. Therefore, the benefit of antiplatelet agents in infective endocarditis prevention has been questioned. Besides aspirin, it has been discovered that the platelet P2Y12 receptor antagonist ticagrelor has antibacterial properties in addition to its potent antiplatelet activity. Furthermore, a recent study in mice and a case report remarkably indicated the ability of this drug to eradicate Staphylococcus aureus bacteremia. This review will focus on current knowledge on antibacterial activity of ticagrelor, compared to aspirin, pointing out main unanswered questions. The goal is to provide food for thought as to whether a prior ticagrelor therapy might be beneficial for the prevention of infective endocarditis.

Ticagrelor and the risk of infections during hospitalization in patients with ST-elevation myocardial infarction undergoing percutaneous coronary intervention

BACKGROUND AND AIMS

Although ticagrelor exerts an antibacterial activity, its effect on infections in patients with ST-segment elevation myocardial infarction (STEMI) undergoing percutaneous coronary intervention (PCI) is unclear. We aimed to assess whether ticagrelor and clopidogrel affect infections in these patients during hospitalization.

METHODS

A total of 2116 consecutive patients with STEMI undergoing PCI were divided into the ticagrelor (n = 388) and clopidogrel (n = 1728) groups. The primary outcome was infection onset. Secondary outcomes were in-hospital all-cause death and major adverse cardiovascular and cerebrovascular events (MACCE). Propensity score analyses were conducted to test the robustness of the results.

RESULTS

Infections developed in 327 (15.4%) patients. There was no significant difference in infection between both groups (ticagrelor vs. clopidogrel: 13.1% vs. 16.0%, p = 0.164). Patients in the ticagrelor group had lower rates of in-hospital all-cause death and MACCE than patients in the clopidogrel group. Multivariate logistic regression analysis determined that ticagrelor and clopidogrel had a similar preventive effect on infections during hospitalization (adjusted odds ratio [OR] = 1.20; 95% confidence interval [CI] = 0.80-1.78, p = 0.380). Compared to the patients treated with clopidogrel, patients treated with ticagrelor had a slightly lower risk of other outcomes, but no statistical difference. Propensity score analyses demonstrated similar results for infections and other outcomes.

CONCLUSIONS

Compared with clopidogrel treatment, ticagrelor treatment did not significantly alter the risk of infections during hospitalization among STEMI patients undergoing PCI, but was associated with a slightly lower risk of in-hospital all-cause death and MACCE.

Coagulopathy and sepsis: Pathophysiology, clinical manifestations and treatment

Sepsis is a complex syndrome with a high incidence, increasing by 8.7% annually over the last 20 years. Coagulopathy is a leading factor associated with mortality in patients with sepsis and range from slight thrombocytopenia to fatal disorders, such as disseminated intravascular coagulation (DIC). Platelet reactivity increases during sepsis but prospective trials of antiplatelet therapy during sepsis have been disappointing. Thrombocytopenia is a known predictor of worse prognosis during sepsis. The mechanisms underlying thrombocytopenia in sepsis have yet to be fully understood but likely involves decreased platelet production, platelet sequestration and increased consumption. DIC is an acquired thrombohemorrhagic syndrome, resulting in intravascular fibrin formation, microangiopathic thrombosis, and subsequent depletion of coagulation factors and platelets. DIC can be resolved with treatment of the underlying disorder, which is considered the cornerstone in the management of this syndrome. This review presents the current knowledge on the pathophysiology, diagnosis, and treatment of sepsis-associated coagulopathies.