Receptor Inhibitor Eptifibatide Research Articles

Mechanism of Pulmonary Thrombosis in Hemolytic Disorders

Hemolysis is a hallmark of various inherited or acquired blood disorders including sickle cell disease, thalassemia, paroxysmal nocturnal hemoglobinuria, thrombotic thrombocytopenic purpura and hemolytic-uremic syndrome. Epidemiological evidence suggests that in situ pulmonary thrombosis is a major pathological event contributing to cardiopulmonary morbidities affecting patients with hemolytic disorders. Intravascular hemolysis promotes the release of erythrocyte-derived damage associated molecular patterns (eDAMPs) molecules such as cell free hemoglobin (Hb), heme and adenosine diphosphate (ADP). Although these eDAMPS may activate platelets, promote endothelial dysfunction and drive sterile thrombo-inflammation, the pathogenesis of pulmonary thrombosis in hemolytic disorders and the role of platelets in this process remains unclear. Intravascular hemolysis in C57BL/6 (WT) mice was induced by intravenous (IV) administration of deionized water (H2O). Alternatively, eDAMPs or tissue derived DAMPs relevant to hemolysis or endothelial injury were administered IV to WT mice. The pulmonary microcirculation was visualized using quantitative intravital fluorescence lung microscopy (qFILM). Fluorochrome-conjugated anti-mouse CD49b Ab and dextran were administered IV for in vivo staining of circulating platelets and visualization of blood vessels, respectively. Time series of qFILM images were collected at baseline and post IV administration of agonists to assess pulmonary thrombosis. IV administration of H2O led to arrival of platelet-rich thrombi in the pulmonary arterioles that occluded the arteriolar bottle-necks located at the junction of pulmonary arterioles and capillaries leading to their transient obstruction. DAMPs such as ADP, collagen, thrombin and tissue factor also triggered dose-dependent PT in mice. Identical to IV H2O, DAMPs triggered pulmonary thrombosis also involved entrapment of platelet-rich thrombi in the arteriolar bottle-necks, which led to ischemia in the pulmonary arteriole and the down-stream capillaries. Interestingly, pretreatment with IV heparin (300 U/kg) prevented TF-induced but not ADP-triggered pulmonary thrombosis in mice. In contrast, IV administration of αIIbβ3 receptor inhibitor eptifibatide (10 mg/kg) completely abrogated TF-, collagen and ADP-dependent PT. Our current findings provide the first real-time in vivo visual evidence establishing that intravascular hemolysis directly induces pulmonary thrombosis, which involves entrapment of platelet-rich thrombi in the pre-capillary pulmonary arterioles. Our results are the first to identify that platelet activation and procoagulant activity contribute to pathogenesis of hemolysis induced pulmonary thrombosis. Disclosures Ragni: OPKO: Research Funding; Bioverativ/Sanofi: Other: Advisory Board, Research Funding; Shire/Takeda: Other: Advisory Board, Research Funding; Sangamo: Research Funding; Spark Therapeutics: Other: Advisory Board, Research Funding; Alnylam/Sanofi: Other: Advisory Board, Research Funding; BioMarin: Other: Advisory Board, Research Funding. Neal:Janssen Pharmaceuticals: Consultancy, Membership on an entity's Board of Directors or advisory committees; CSL Behring: Membership on an entity's Board of Directors or advisory committees. Gladwin:Bayer Pharmaceuticals: Other: Co-investigator; United Therapeutics: Patents & Royalties: Co-inventor on an NIH government patent for the use of nitrite salts in cardiovascular diseases ; Globin Solutions, Inc: Patents & Royalties: Provisional patents for the use of recombinant neuroglobin and heme-based molecules as antidotes for CO poisoning.

Platelets Induce Apoptosis during Sepsis in a Contact-Dependent Manner That Is Inhibited by GPIIb/IIIa Blockade

PurposeEnd-organ apoptosis is well-described in progressive sepsis and Multiple Organ Dysfunction Syndrome (MODS), especially where platelets accumulate (e.g. spleen and lung). We previously reported an acute sepsis-induced cytotoxic platelet phenotype expressing serine protease granzyme B. We now aim to define the site(s) of and mechanism(s) by which platelet granzyme B induces end-organ apoptosis in sepsis.MethodsEnd-organ apoptosis in murine sepsis (i.e. polymicrobial peritonitis) was analyzed by immunohistochemistry. Platelet cytotoxicity was measured by flow cytometry following 90 minute ex vivo co-incubation with healthy murine splenocytes. Sepsis progression was measured via validated preclinical murine sepsis score.Measurements and Main ResultsThere was evident apoptosis in spleen, lung, and kidney sections from septic wild type mice. In contrast, there was a lack of TUNEL staining in spleens and lungs from septic granzyme B null mice and these mice survived longer following induction of sepsis than wild type mice. In co-incubation experiments, physical separation of septic platelets from splenocytes by a semi-permeable membrane reduced splenocyte apoptosis to a rate indistinguishable from negative controls. Chemical separation by the platelet GPIIb/IIIa receptor inhibitor eptifibatide decreased apoptosis by 66.6±10.6% (p = 0.008). Mice treated with eptifibatide in vivo survived longer following induction of sepsis than vehicle control mice.ConclusionsIn sepsis, platelet granzyme B-mediated apoptosis occurs in spleen and lung, and absence of granzyme B slows sepsis progression. This process proceeds in a contact-dependent manner that is inhibited ex vivo and in vivo by the platelet GPIIb/IIIa receptor inhibitor eptifibatide. The GPIIb/IIIa inhibitors and other classes of anti-platelet drugs may be protective in sepsis.

Mechanisms of C-reactive protein, interleukin-6 and soluble CD40L blood concentration changes after coronary stent implantation

Background: The pathway linking inflammation and thrombosis has been extensively studied. Experimental data support that arterial thrombosis also induces a detectable inflammatory response, which in turn, activates prothrombotic pathways closing a vicious circle that interconnects inflammation and thrombosis. Aim: We designed this study to investigate the causes of inflammatory markers increase after coronary angioplasty. Methods: We analyzed the interrelationship of thrombotic and inflammatory markers and the effect of blocking thrombus formation on the inflammatory response in 50 patients undergoing high thrombotic risk coronary angioplasty. The relationship of platelet number to soluble CD40 Ligand, Interleukin-6 and C-reactive protein blood levels was studied. Half of the study population was treated with standard antithrombotic drugs and the other half with the standard therapy plus platelet GP IIb-IIIa receptor inhibitor Eptifibatide. Results: There was a clear correlation between basal platelet count and sCD40L basal levels, post-angioplasty sCD40L increase and post-angioplasty IL-6 levels and post-angioplasty IL-6 levels with post-angioplasty CRP levels. Postangioplasty CRP, IL-6 and sCD40L blood levels were influenced by GP IIb-IIIa treatment in patients with angiographic thrombus. Conclusion: Platelet aggregation induces a proinflammatory response which is blocked by a GP IIb-IIIa inhibitor agent, particularly in patients with patent angiographic thrombus.

Perioperative Management of Patients on Clopidogrel (Plavix) Undergoing Major Lung Resection

Management of patients requiring antiplatelet therapy with clopidogrel (Plavix) and major lung resection must balance the risks of bleeding and cardiovascular events. We reviewed our experience with patients treated with clopidogrel perioperatively to examine outcomes, including results of a new strategy for high-risk patients. Patients who underwent major lung resection and received perioperative clopidogrel between January 2005 and September 2010 were reviewed. Initially, clopidogrel management consisted of discontinuation approximately 5 days before surgery and resumption immediately after surgery. After July 2010, high-risk patients (drug-eluting coronary stent placement within prior year or previous coronary event after clopidogrel discontinuation) were admitted 2 to 3 days preoperatively and bridged with the intravenous glycoprotein IIb/IIIa receptor inhibitor eptifibatide (Integrilin) according to a multidisciplinary cardiology/anesthesiology/thoracic surgery protocol. Outcomes were compared with control patients (matched for preoperative risk factors and extent of pulmonary resection) who did not receive perioperative clopidogrel. Fifty-four patients who had major lung resection between January 2005 and September 2010 and received clopidogrel perioperatively were matched with 108 control subjects. Both groups had similar mortality, postoperative length of stay, and no differences in the rates of perioperative transfusions, reoperations for bleeding, myocardial infarctions, and strokes. Seven of the 54 clopidogrel patients were admitted preoperatively for an eptifibatide bridge. Two of these patients received perioperative transfusions, but there were no deaths, reoperations, myocardial infarctions, or stroke. Patients taking clopidogrel can safely undergo major lung resection. Treatment with an eptifibatide bridge may minimize the risk of cardiovascular events in higher risk patients.

Platelet aggregation inhibition blocks C-reactive protein and interleukin-6 (IL-6) elevation after the coronary angioplasty: Effect of the −174 G/C IL-6 gene polymorphism

C-reactive protein (CRP), interleukin-6 (IL-6), and the -174 GC IL-6 gene polymorphism were analyzed after coronary angioplasty in 50 patients, 25 of whom were treated with the glycoprotein IIb/IIIa platelet receptor inhibitor eptifibatide for 24 hours. It was found that glycoprotein IIb/IIIa inhibition significantly blocked postangioplasty CRP increases in all patients but blocked IL-6 increases only in patients carrying the -174 GG genotype.

Intracranial clot lysis with intravenous microbubbles and transcranial ultrasound in swine.

Destruction of microbubbles by transcutaneous low-frequency ultrasound (LFUS) has been used to lyse adjacent clot and recanalize acutely thrombosed vessels. LFUS with intraarterial microbubbles has been shown to lyse cerebral clot rapidly in pigs without thrombolytic drugs. We hypothesized that intravenous platelet-targeted microbubbles with LFUS may be a rapid noninvasive technique to recanalize thrombosed intracerebral vessels. After angiography, 0.5 cc of autogenous thrombus was injected into 1 ascending pharyngeal artery of a pig, occluding it and the rete mirabile. These vessels connect the carotid to the internal carotid and are the main cerebral blood supply. Saline control or intravenous decafluorobutane-sonicated dextrose albumin microbubbles tagged with a subtherapeutic quantity of glycoprotein 2b/3a receptor inhibitor eptifibatide (75 U/kg plus 12 cc of microbubbles administered over 21 minutes), or eptifibatide control, was given with transcutaneous temporal LFUS (1 MHz at 2.0 W/cm2) for 24 minutes. Angiography followed with scoring of declotting and flow. The same protocol was repeated on the contralateral side with the other test fluid so each animal received a saline control and either tagged microbubble or eptifibatide alone. Fifteen pigs completed the protocol with a mean clot age of 4.6 hours. Using tagged microbubbles, 6 of 8 achieved success compared with 0 of 7 receiving eptifibatide alone (P=0.007) and 1 of 15 receiving saline alone (P=0.02). Intravenous platelet-targeted microbubbles combined with transcranial LFUS can rapidly open acute intracranial thrombotic occlusions. Further development for ischemic stroke therapy is justified.

Effect of eptifibatide on angiographic complications during percutaneous coronary intervention in the IMPACT- (integrilin to minimize platelet aggregation and coronary thrombosis) II Trial

We sought to determine whether eptifibatide reduces elevation of creatine kinase (CK)-MB isoenzyme release during coronary intervention by preventing angiographic complications, by minimizing the sequelae of angiographic complications once they occur, or by other mechanisms. In the Integrilin to Minimize Platelet Aggregation and Coronary Thrombosis trial, patients underwent coronary intervention during treatment with placebo versus the glycoprotein IIb/IIIa receptor inhibitor eptifibatide. Eptifibatide decreased ischemic complications at 24 hours and 30 days. CK-MB elevations and in-laboratory angiographic complications (including major dissection, distal embolization, residual thrombus, abrupt closure, residual stenosis >50%, and side branch occlusion) were prospectively recorded. The incidence of any angiographic complication was lower in eptifibatide-treated patients (33%) than in placebo-treated patients (38%, p = 0.019). For patients with angiographic complications, there was a trend toward a reduced incidence of any elevation in CK-MB in the first 24 hours (29%, 135/0.75 eptifibatide dose; 33%, 135/0.5 eptifibatide dose; 37%, placebo). Among patients without angiographic complications, there was a similar trend toward fewer abnormal CK-MB levels in patients receiving eptifibatide (17% and 18% in eptifibatide arms vs 21% placebo). Thus, eptifibatide reduces angiographically evident complications during coronary intervention, but this effect accounts for only 1/3 of the reduced frequency of CK-MB elevations observed with eptifibatide. When angiographic complications occur, eptifibatide reduces rates of subsequent CK-MB elevation, accounting for another 1/3 of the reduction in CK-MB elevations. Finally, eptifibatide reduces the incidence of periprocedural CK-MB elevations in patients without angiographically evident complications, accounting for 1/3 of eptifibatide’s overall effect in reducing of CK-MB elevations in patients undergoing percutanous coronary intervention.