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      Ticagrelor Exerts Immune-Modulatory Effect by Attenuating Neutrophil Extracellular Traps

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          Abstract

          Neutrophils through the release of neutrophil extracellular traps (NETs) containing active tissue factor (TF) are key components of thrombo-inflammation. Platelets-neutrophils interplay in ST elevation myocardial infarction (STEMI) promotes NET formation via inorganic polyphosphates (polyP) released by thrombin-activated platelets. NETs, however, are also induced by biomaterials in a platelet-independent manner. Considering the possible pleiotropic effects of Ticagrelor beyond platelet inhibition and the clinical need for novel antithrombotic strategies targeting inflammation, we investigated the effects of Ticagrelor on polyP and stent-induced NETs in STEMI. Neutrophils from healthy individuals and patients receiving Ticagrelor were stimulated with polyP or drug-eluting stents (DES) to produce NETs. To induce TF expression, neutrophils were further incubated with plasma obtained from the infarct-related artery (IRA) of STEMI patients. The effects of Ticagrelor on NETs and TF loading were assessed using fluorescence microscopy, flow cytometry, myeloperoxidase(MPO)/DNA complex ELISA, and a Western blot. Ticagrelor interrupts platelet–neutrophil interaction by attenuating NETs induced by polyP. However, Ticagrelor does not affect polyP secretion from thrombin-activated platelets. Similarly, the intracellular production of TF in neutrophils triggered by IRA plasma is not hindered by Ticagrelor. Furthermore, DES induce NETs and synchronous stimulation with IRA plasma leads to the formation of thrombogenic TF-bearing NETs. Ticagrelor inhibits stent-induced NET release. These findings suggest a novel immune-modulatory effect of Ticagrelor when it attenuates the formation of thrombogenic NETs.

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          Most cited references47

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          Platelet TLR4 activates neutrophil extracellular traps to ensnare bacteria in septic blood.

          It has been known for many years that neutrophils and platelets participate in the pathogenesis of severe sepsis, but the inter-relationship between these players is completely unknown. We report several cellular events that led to enhanced trapping of bacteria in blood vessels: platelet TLR4 detected TLR4 ligands in blood and induced platelet binding to adherent neutrophils. This led to robust neutrophil activation and formation of neutrophil extracellular traps (NETs). Plasma from severely septic humans also induced TLR4-dependent platelet-neutrophil interactions, leading to the production of NETs. The NETs retained their integrity under flow conditions and ensnared bacteria within the vasculature. The entire event occurred primarily in the liver sinusoids and pulmonary capillaries, where NETs have the greatest capacity for bacterial trapping. We propose that platelet TLR4 is a threshold switch for this new bacterial trapping mechanism in severe sepsis.
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            Netting neutrophils in autoimmune small-vessel vasculitis.

            Small-vessel vasculitis (SVV) is a chronic autoinflammatory condition linked to antineutrophil cytoplasm autoantibodies (ANCAs). Here we show that chromatin fibers, so-called neutrophil extracellular traps (NETs), are released by ANCA-stimulated neutrophils and contain the targeted autoantigens proteinase-3 (PR3) and myeloperoxidase (MPO). Deposition of NETs in inflamed kidneys and circulating MPO-DNA complexes suggest that NET formation triggers vasculitis and promotes the autoimmune response against neutrophil components in individuals with SVV.
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              Neutrophil Extracellular Traps Directly Induce Epithelial and Endothelial Cell Death: A Predominant Role of Histones

              Neutrophils play an important role in innate immunity by defending the host organism against invading microorganisms. Antimicrobial activity of neutrophils is mediated by release of antimicrobial peptides, phagocytosis as well as formation of neutrophil extracellular traps (NET). These structures are composed of DNA, histones and granular proteins such as neutrophil elastase and myeloperoxidase. This study focused on the influence of NET on the host cell functions, particularly on human alveolar epithelial cells as the major cells responsible for gas exchange in the lung. Upon direct interaction with epithelial and endothelial cells, NET induced cytotoxic effects in a dose-dependent manner, and digestion of DNA in NET did not change NET-mediated cytotoxicity. Pre-incubation of NET with antibodies against histones, with polysialic acid or with myeloperoxidase inhibitor but not with elastase inhibitor reduced NET-mediated cytotoxicity, suggesting that histones and myeloperoxidase are responsible for NET-mediated cytotoxicity. Although activated protein C (APC) did decrease the histone-induced cytotoxicity in a purified system, it did not change NET-induced cytotoxicity, indicating that histone-dependent cytotoxicity of NET is protected against APC degradation. Moreover, in LPS-induced acute lung injury mouse model, NET formation was documented in the lung tissue as well as in the bronchoalveolar lavage fluid. These data reveal the important role of protein components in NET, particularly histones, which may lead to host cell cytotoxicity and may be involved in lung tissue destruction.
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                Author and article information

                Journal
                Int J Mol Sci
                Int J Mol Sci
                ijms
                International Journal of Molecular Sciences
                MDPI
                1422-0067
                21 May 2020
                May 2020
                : 21
                : 10
                : 3625
                Affiliations
                [1 ]Laboratory of Molecular Hematology, Department of Medicine, Democritus University of Thrace, 68100 Alexandroupolis, Greece; alexmitsios@ 123456gmail.com (A.M.); akrivika@ 123456hotmail.com (A.C.); thanos.arampatzioglou@ 123456gmail.com (A.A.); iliana_angelidou@ 123456yahoo.gr (I.A.); kritis@ 123456med.duth.gr (K.R.); dstakos@ 123456med.duth.gr (D.S.)
                [2 ]Natural Products Synthesis and Bioorganic Chemistry Laboratory, Institute of Nanoscience and Nanotechnology, NCSR “Demokritos”, 15310 Athens, Greece; v.vidali@ 123456inn.demokritos.gr
                [3 ]First Department of Internal Medicine, University Hospital of Alexandroupolis, Democritus University of Thrace, 68100 Alexandroupolis, Greece
                [4 ]Cardiology Department, University Hospital of Alexandroupolis, Democritus University of Thrace, 68100 Alexandroupolis, Greece
                Author notes
                [* ]Correspondence: pskendro@ 123456med.duth.gr
                [†]

                These authors contributed equally to this work.

                Author information
                https://orcid.org/0000-0001-9020-8726
                Article
                ijms-21-03625
                10.3390/ijms21103625
                7279443
                32455533
                896573fb-7915-485b-923b-addfdfda0a11
                © 2020 by the authors.

                Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ( http://creativecommons.org/licenses/by/4.0/).

                History
                : 23 April 2020
                : 19 May 2020
                Categories
                Article

                Molecular biology
                neutrophil,neutrophil extracellular traps,inorganic polyphosphate,thrombo-inflammation,ticagrelor,myocardial infraction

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