apyrase and Myocardial-Infarction

Extracellular nucleotides and nucleosides act as signaling molecules involved in a wide spectrum of biological effects. Their levels are controlled by a complex cell surface-located group of enzymes called ectonucleotidases. There are four major families of ectonucleotidases, nucleoside triphosphate diphosphohydrolases (NTPDases/CD39), ectonucleotide pyrophosphatase/phosphodiesterases (E-NPPs), alkaline phosphatases and ecto-5'-nucleotidase. In the last few years, substantial progress has been made toward the molecular identification of members of the ectonucleotidase families and their enzyme structures and functions. In this review, there is an emphasis on the involvement of NTPDase and 5'-nucleotidase activities in disease processes in several tissues and cell types. Brief background information is given about the general characteristics of these enzymes, followed by a discussion of their roles in thromboregulatory events in diabetes, hypertension, hypercholesterolemia and cancer, as well as in pathological conditions where platelets are less responsive, such as in chronic renal failure. In addition, immunomodulation and cell-cell interactions involving these enzymes are considered, as well as ATP and ADP hydrolysis under different clinical conditions related with alterations in the immune system, such as acute lymphoblastic leukemia (ALL), B-chronic lymphocytic leukemia (B-CLL) and infections associated with human immunodeficiency virus (HIV). Finally, changes in ATP, ADP and AMP hydrolysis induced by inborn errors of metabolism, seizures and epilepsy are discussed in order to highlight the importance of these enzymes in the control of neuronal activity in pathological conditions. Despite advances made toward understanding the molecular structure of ectonucleotidases, much more investigation will be necessary to entirely grasp their role in physiological and pathological conditions.

Topics: 5'-Nucleotidase; Adenosine; Adenosine Triphosphate; Animals; Antigens, CD; Apyrase; Atherosclerosis; Blood Coagulation; Blood Platelets; Cell Communication; Demyelinating Diseases; Epilepsy; Humans; Metabolism, Inborn Errors; Myocardial Infarction; Neoplasms; Platelet Activation; Platelet Aggregation; Seizures; Signal Transduction; Tamoxifen; Thrombosis

The occurrence of intramyocardial hemorrhage (IMH) and microvascular obstruction (MVO) in myocardial infarction (MI), known as severe ischemia/reperfusion injury (IRI), has been associated with adverse remodeling. APT102, a soluble human recombinant ecto-nucleoside triphosphate diphosphohydrolase-1, can hydrolyze extracellular nucleotides to attenuate their prothrombotic and proinflammatory effects. The purpose of this study was to temporally evaluate the therapeutic effect of APT102 on IRI in rats and to elucidate the evolution of IRI in the acute stage using cardiovascular magnetic resonance imaging (CMRI).. Fifty-four rats with MI, induced by ligation of the origin of the left anterior descending coronary artery for 60 minutes, were randomly divided into the APT102 (n = 27) or control (n = 27) group. Intravenous infusion of APT102 (0.3 mg/kg) or placebo was administered 15 minutes before reperfusion, and then 24 hours, 48 hours, 72 hours, and on day 4 after reperfusion. CMRI was performed at 24 hours, 48 hours, 72 hours, and on day 5 post-reperfusion using a 7T system and the hearts were collected for histopathological examination. Cardiac function was quantified using cine imaging and IMH/edema using T2 mapping, and infarct/MVO using late gadolinium enhancement.. The extent of infarction (. APT102 can significantly alleviate damage to the ischemic myocardium and microvasculature. IMH size peaked at 48 hours post reperfusion and IMH is a downstream consequence of MVO. IMH may be a potential therapeutic target to prevent adverse remodeling in MI.

Topics: Animals; Apyrase; Drug Administration Schedule; Female; Heart Ventricles; Infusions, Intravenous; Linear Models; Magnetic Resonance Imaging, Cine; Microvessels; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium; Placebo Effect; Rats; Rats, Sprague-Dawley; Recombinant Proteins; Ventricular Function, Left

Prior work suggests that ischemic preconditioning increases the level of CD39 in the heart and contributes to cardiac protection. Therefore, we examined if targeted cardiac expression of CD39 protects against myocardial injury.. Mice with cardiac-specific expression of human CD39 (αMHC/hCD39-Tg) were generated, characterized and subjected to left coronary artery ischemia-reperfusion injury and infarct size at 24h following injury quantified.. αMHC/hCD39-Tg mice have increased in cardiac ATPase and ADPase activity compared to WT littermates. The increased activity in αMHC/hCD39-mice was inhibited by the CD39 antagonist sodium polyoxotungstate (POM-1). Measurement of basal cardiac function by echocardiography revealed that αMHC/hCD39-Tg mice have a lower resting heart rate and increased stroke volume. In response to myocardial ischemia, systolic and diastolic function was better preserved in αMHC/hCD39-Tg compared to WT mice. Comparison of Tau also revealed preserved cardiac relaxation during ischemia in αMHC/hCD39-Tg hearts. Assessment of myocardial infarct size in response to 60min of ischemia and 24h of reperfusion demonstrated a significant reduction in infarct size in αMHC/hCD39-Tg hearts. Analysis of isolated cardiomyocytes revealed no basal difference in calcium transients between WT and αMHC/hCD39-Tg cardiomyocytes. However, in response to isoproterenol stimulation, there was a trend toward lower calcium transients in αMHC/hCD39 cardiomyocytes suggesting less calcium accumulation in response to metabolic stress.. Cardiac-specific expression of CD39 reduces myocardial dysfunction and infarct size following ischemia-reperfusion injury. Increasing nucleotidase expression in the heart may be a novel approach to protect the heart from ischemic injury.

Topics: Animals; Antigens, CD; Apyrase; Calcium; Disease Models, Animal; Echocardiography; Gene Expression; Heart Rate; Humans; Isoproterenol; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Myocardial Infarction; Myocardial Reperfusion Injury; Myocytes, Cardiac; Stress, Physiological; Stroke Volume

In patients with acute myocardial infarction undergoing reperfusion therapy to restore blood flow through blocked arteries, simultaneous inhibition of platelet P2Y12 receptors with the current standard of care neither completely prevents recurrent thrombosis nor provides satisfactory protection against reperfusion injury. Additionally, these antiplatelet drugs increase the risk of bleeding. To devise a different strategy, we engineered and optimized the apyrase activity of human nucleoside triphosphate diphosphohydrolase-3 (CD39L3) to enhance scavenging of extracellular adenosine diphosphate, a predominant ligand of P2Y12 receptors. The resulting recombinant protein, APT102, exhibited greater than four times higher adenosine diphosphatase activity and a 50 times longer plasma half-life than did native apyrase. Treatment with APT102 before coronary fibrinolysis with intravenous recombinant human tissue-type plasminogen activator in conscious dogs completely prevented thrombotic reocclusion and significantly decreased infarction size by 81% without increasing bleeding time. In contrast, clopidogrel did not prevent coronary reocclusion and increased bleeding time. In a murine model of myocardial reperfusion injury caused by transient coronary artery occlusion, APT102 also decreased infarct size by 51%, whereas clopidogrel was not effective. These preclinical data suggest that APT102 should be tested for its ability to safely and effectively maximize the benefits of myocardial reperfusion therapy in patients with arterial thrombosis.

Topics: Adenosine Diphosphate; Animals; Apyrase; Clopidogrel; Coronary Circulation; Dogs; Fibrinolysis; Hemorrhage; Humans; Mice, Inbred C57BL; Myocardial Infarction; Myocardial Reperfusion Injury; Piperazines; Platelet Aggregation; Prasugrel Hydrochloride; Risk Factors; Thiophenes; Thrombosis; Ticlopidine; Time Factors; Tissue Plasminogen Activator; Treatment Outcome; Vascular Patency

The ectoenzymes CD39 and CD73 are expressed by a broad range of immune cells and promote the extracellular degradation of nucleotides to anti-inflammatory adenosine. This study explored the abundance of CD73 and CD39 on circulating and resident cardiac leukocytes and coronary endothelial cells under control conditions and in response to inflammation following myocardial ischemia and reperfusion (I/R).. A method was elaborated to permit FACS analysis of non-myocardial cells (resident leukocytes, coronary endothelium and CD31(-) CD45(-) cells) of the unstressed heart. Under control conditions the murine heart contained 2.3 × 10(3) resident leukocytes/mg tissue, the most prominent fraction being antigen-presenting mononuclear cells (CD11b(+) CD11c(+) F4/80(+) MHCII(+)) followed by B-cells, monocytes and T-cells. CD73 was highly expressed on circulating and resident cardiac lymphoid cells with little expression on myeloid cells, while the opposite was true for CD39. Cardiomyocytes and erythrocytes do not measurably express CD39/CD73 and CD39 dominates on coronary endothelium. Three days after I/R, CD73 was significantly upregulated on invading granulocytes (2.8-fold) and T-cells (1.5-fold). Compared with coronary endothelial cells, CD73 associated with leukocytes comprised 2/3 of the total cardiac CD73.. Our study suggests that extracellular ATP formed during I/R is preferentially degraded by CD39 present on myeloid cells, while the formation of immunosuppressive adenosine is mainly catalysed by CD73 present on granulocytes and lymphoid cells. Upregulated CD73 on granulocytes and T-cells infiltrating the injured heart is consistent with the existence of an autocrine adenosinergic loop which may promote the healing process.

Topics: 5'-Nucleotidase; Adenosine; Adenosine Triphosphate; Animals; Antigens, CD; Apyrase; B-Lymphocytes; Cells, Cultured; Erythrocytes; Female; Flow Cytometry; Granulocytes; Leukocytes; Mice; Mice, Inbred C57BL; Myocardial Infarction; Myocytes, Cardiac; T-Lymphocytes

Modulation of purinergic signaling is critical to myocardial homeostasis. Ectonucleoside triphosphate diphosphohydrolase 1 (ENTPD-1; CD39) which converts the proinflammatory molecules ATP or ADP to AMP is a key regulator of purinergic modulation. However, the salutary effects of transgenic over expression of ENTPD-1 on myocardial response to ischemic injury have not been tested to date. Therefore we hypothesized that ENTPD-1 over expression affords myocardial protection from ischemia-reperfusion injury via specific cell signaling pathways. ENTPD-1 transgenic mice, which over express human ENTPDase-1, and wild-type (WT) littermates were subjected to either ex vivo or in vivo ischemia-reperfusion injury. Infarct size, inflammatory cell infiltrate and intracellular signaling molecule activation were evaluated. Infarct size was significantly reduced in ENTPD-1 versus WT hearts in both ex vivo and in vivo studies. Following ischemia-reperfusion injury, ENTPD-1 cardiac tissues demonstrated an increase in the phosphorylation of the cellular signaling molecule extracellular signal-regulated kinases 1/2 (ERK 1/2) and glycogen synthase kinase-3β (GSK-3β). Resistance to myocardial injury was abrogated by treatment with a non-selective adenosine receptor antagonist, 8-SPT or the more selective A(2B) adenosine receptor antagonist, MRS 1754, but not the A(1) selective antagonists, DPCPX. Additionally, treatment with the ERK 1/2 inhibitor PD98059 or the mitochondrial permeability transition pore opener, atractyloside, abrogated the cardiac protection provided by ENTPDase-1 expression. These results suggest that transgenic ENTPDase-1 expression preferentially conveys myocardial protection from ischemic injury via adenosine A(2B) receptor engagement and associated phosphorylation of the cellular protective signaling molecules, Akt, ERK 1/2 and GSK-3β that prevents detrimental opening of the mitochondrial permeability transition pore.

Topics: Animals; Antigens, CD; Apyrase; Disease Models, Animal; Gene Expression; Humans; Mice; Mice, Inbred C57BL; Mice, Transgenic; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Myocardial Infarction; Myocardial Reperfusion Injury; Phosphorylation; Receptor, Adenosine A2B; Signal Transduction

Ectonucleotidase dependent adenosine generation has been implicated in preconditioning related cardioprotection against ischemia-reperfusion injury, and treatment with a soluble ectonucleotidase has been shown to reduce myocardial infarct size (IS) when applied prior to induction of ischemia. However, ectonucleotidase treatment according to a clinically applicable protocol, with administration only after induction of ischemia, has not previously been evaluated. We therefore investigated if treatment with the ectonucleotidase apyrase, according to a clinically applicable protocol, would reduce IS and microvascular obstruction (MO) in a large animal model.. A percutaneous coronary intervention balloon was inflated in the left anterior descending artery for 40 min, in 16 anesthetized pigs (40-50 kg). The pigs were randomized to 40 min of 1 ml/min intracoronary infusion of apyrase (10 U/ml, n = 8) or saline (0.9 mg/ml, n = 8), twenty minutes after balloon inflation. Area at risk (AAR) was evaluated by ex vivo SPECT. IS and MO were evaluated by ex vivo MRI.. No differences were observed between the apyrase group and saline group with respect to IS/AAR (75.7 +/- 4.2% vs 69.4 +/- 5.0%, p = NS) or MO (10.7 +/- 4.8% vs 11.4 +/- 4.8%, p = NS), but apyrase prolonged the post-ischemic reactive hyperemia.. Apyrase treatment according to a clinically applicable protocol, with administration of apyrase after induction of ischemia, does not reduce myocardial infarct size or microvascular obstruction.

Topics: Animals; Apyrase; Blood Pressure; Disease Models, Animal; Female; Heart Rate; Male; Myocardial Infarction; Myocardial Reperfusion Injury; Random Allocation; Swine

Hypoxia is common to several inflammatory diseases, where multiple cell types release adenine-nucleotides (particularly adenosine triphosphate/adenosine diphosphate). Adenosine triphosphate/adenosine diphosphate is metabolized to adenosine through a 2-step enzymatic reaction initiated by CD39 (ectonucleoside-triphosphate-diphosphohydrolase-1). Thus, extracellular adenosine becomes available to regulate multiple inflammatory endpoints. Here, we hypothesized that hypoxia transcriptionally up-regulates CD39 expression. Initial studies revealed hypoxia-dependent increases in CD39 mRNA and immunoreactivity on endothelia. Examination of the human CD39 gene promoter identified a region important in hypoxia inducibility. Multiple levels of analysis, including site-directed mutagenesis, chromatin immunoprecipitation, and inhibition by antisense, revealed a critical role for transcription-factor Sp1 in hypoxia-induction of CD39. Using a combination of cd39(-/-) mice and Sp1 small interfering RNA in in vivo cardiac ischemia models revealed Sp1-mediated induction of cardiac CD39 during myocardial ischemia. In summary, these results identify a novel Sp1-dependent regulatory pathway for CD39 and indicate the likelihood that CD39 is central to protective responses to hypoxia/ischemia.

Topics: Animals; Antigens, CD; Apyrase; Cells, Cultured; Disease Models, Animal; Endothelial Cells; Female; Gene Expression Regulation; Humans; Hypoxia; Male; Mice; Mice, Inbred C57BL; Mutagenesis, Site-Directed; Myocardial Infarction; Myocardial Reperfusion Injury; Promoter Regions, Genetic; RNA, Messenger; RNA, Small Interfering; Sp1 Transcription Factor

Extracellular adenosine, generated from extracellular nucleotides via ectonucleotidases, binds to specific receptors and provides cardioprotection from ischemia and reperfusion. In the present study, we studied ecto-enzymatic ATP/ADP-phosphohydrolysis by select members of the ectonucleoside triphosphate diphosphohydrolase (E-NTPDase) family during myocardial ischemia.. As a first step, we used a murine model of myocardial ischemia and in situ preconditioning and performed pharmacological studies with polyoxometalate 1, a potent E-NTPDase inhibitor (Na6[H2W12O40]). Polyoxometalate 1 treatment increased infarct sizes and abolished beneficial effects of preconditioning. To define relative contributions of distinct E-NTPDases, we investigated transcriptional responses of E-NTPDases 1 to 3 and 8 to preconditioning. We noted robust and selective induction of E-NTPDase 1 (CD39) transcript and protein. Histological analysis of preconditioned myocardium localized CD39 induction to endothelia and myocytes. Cd39-/- mice exhibited larger infarct sizes with ischemia (cd39+/+ 43.0+/-3.3% versus cd39-/- 52%+/-1.8; P<0.05), and cardioprotection was abrogated by preconditioning (cd39+/+ 13.3%+/-1.5 versus cd39-/- 50.5%+/-2.8; P<0.01). Heightened levels of injury after myocardial ischemia and negligible preconditioning benefits in cd39-/- mice were corrected by infusion of the metabolic product (AMP) or apyrase. Moreover, apyrase treatment of wild-type mice resulted in 43+/-4.2% infarct size reduction (P<0.01).. Taken together, these studies reveal E-NTPDase 1 in cardioprotection and suggest apyrase in the treatment of myocardial ischemia.

Topics: Adenosine; Adenosine Monophosphate; Animals; Antigens, CD; Apyrase; Disease Models, Animal; Enzyme Induction; Ischemic Preconditioning, Myocardial; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Myocardial Infarction; Myocardial Reperfusion Injury; Myocardium

Hypertension is a major risk factor for stroke/myocardial infarction as expression of the atherogenic process. Platelets play a fundamental role in all these disease processes. In physiological conditions there is an equilibrium between pro aggregating and anti aggregating factors. In pathological situations this equilibrium is broken and pro aggregating factors are predominant . Patients with hypertension have an state of hyper-aggregation and dysequilibrium in the production of eicosanoids. Some antihypertensive drugs tend to not only reduce blood pressure to control levels but to reduce platelet aggregation and re-establish the broken equilibrium in eicosanoid production.

Topics: Adult; Aged; Antihypertensive Agents; Apyrase; Cerebrovascular Disorders; Eicosanoids; Endothelium, Vascular; Female; Humans; Hypertension; Male; Middle Aged; Myocardial Infarction; Nitric Oxide; Platelet Aggregation; Platelet Aggregation Inhibitors; Risk Factors; Vasodilation; Venezuela

The de-aggregatory effect of prostacyclin (PGI2) and the rate of spontaneous platelet aggregation (SPA) were studied in vitro in whole blood of 24 males with acute myocardial infarction (MI) and 18 males, patient controls (PC). The de-aggregatory effect of PGI2 and the rate of SPA (measured as a percentage of changes in free platelet number in whole blood) were higher (p less than 0.01) in MI than PC. The de-aggregatory effect of PGI2 in whole blood was higher (p less than 0.05) on the first day of MI than on day 14 following MI. The highest de-aggregatory effect of PGI2 was found in whole blood of patients with MI complicated by ventricular fibrillation. In neither of the groups did the de-aggregatory effect of PGI2 correlate with patients' age, haematocrit, erythrocyte and leucocyte counts, triglycerides, HDL, LDL or total cholesterol levels. In the MI group, de-aggregatory effect of PGI2 was correlated with free platelet concentration (r = -0.59, p less than 0.05), elevation of glutamic oxalacetic transaminase (r = 0.53, p less than 0.05) and creatinine phosphokinase (r = 0.69, p less than 0.001). The de-aggregatory effect of PGI2 in blood of patients with evolving MI did not differ from that in PC. It is concluded that the increased rate of SPA and formation of PGI2-sensitive platelet aggregates in vitro in whole blood of MI patients are secondary to myocardial necrosis.

Topics: Adult; Aged; Apyrase; Coronary Vessels; Epoprostenol; Humans; In Vitro Techniques; Male; Middle Aged; Myocardial Infarction; Platelet Aggregation; Platelet Count

A rapid radioassay was used to characterise the adenosine diphosphatase (ADPase) activities in human plasma. There was a major peak at pH 9.3, 80% of whose activity was attributable to non-specific alkaline phosphatase, with the remaining 20% probably due to a specific ADPase. There was also a small peak of ADPase activity at pH 4.0. Inhibitor and chromatographic studies showed that whilst much of this activity was attributable to non-specific acid phosphatase, there was a discrete acid ADPase. Assays of plasma ADPase activities in vascular disorders, including myocardial infarction, peripheral vascular disease and diabetes mellitus, reveal no alterations from control values. Activities of alkaline ADPase were elevated in both chronic and acute liver failure. Acid ADPase was also increased in chronic liver disease and it is suggested that alterations in ADPase activities in liver disorders may contribute to the haemostatic problems observed in these patients.

Topics: Acid Phosphatase; Acute Disease; Alkaline Phosphatase; Apyrase; Chromatography, Gel; Chronic Disease; Humans; Hydrogen-Ion Concentration; Kinetics; Liver Diseases; Myocardial Infarction; Phosphoric Monoester Hydrolases; Vascular Diseases

To investigate the clinical implications and mechanisms of spontaneous platelet aggregation (SPA) in man, 150 normal subjects, 22 patient controls and 130 patients with vascular insufficiency were studied. SPA was negative in normal subjects and patient controls whereas it was positive in 36 of 66 (54%) patients with transient ischemic attacks, 6 of 32 (19%) patients with stable angina, 7 of 10 (70%) patients with acute myocardial infarction and 11 of 14 (80%) patients with acute peripheral arterial insufficiency. The SPA was inhibited with aspirin in vivo, and inhibited competitively in vitro by low concentrations of aspirin, 2-chloroadenosine, prostaglandin E1 or apyrase but only by high concentrations of heparin or hirudin. Addition of platelet-poor plasma from patients with positive SPA did not cause normal platelets to aggregate. Treatment of patients who had acute peripheral arterial insufficiency with aspirin and dipyridamole prevented SPA with notable clinical improvement of the ischemic changes.

Topics: Adenosine; Adult; Aged; Angina Pectoris; Apyrase; Arterial Occlusive Diseases; Aspirin; Coronary Disease; Dipyridamole; Heparin; Hirudins; Humans; Ischemic Attack, Transient; Middle Aged; Myocardial Infarction; Platelet Aggregation; Prostaglandins E