alpha-Neup5Ac-(2--3)-beta-D-Galp-(1--4)-[alpha-L-Fucp-(1--3)]-D-GlcpNAc and Myocardial-Ischemia

Topics: Angioplasty, Balloon; Animals; Blood Vessels; Myocardial Ischemia; Myocardial Reperfusion Injury; Oligosaccharides; Selectins; Sialyl Lewis X Antigen

Diagnosing acute coronary syndrome in patients presenting with chest discomfort is a challenge. Because acute myocardial ischemia/reperfusion is associated with endothelial upregulation of leukocyte adhesion molecules, which persist even after ischemia has resolved, we hypothesized that microbubbles designed to adhere to endothelial selectins would permit echocardiographic identification of recently ischemic myocardium.. Lipid microbubbles (diameter, 3.3+/-1.7 microm) were synthesized. The selectin ligand sialyl Lewis(x) was conjugated to the microbubble surface (MB(sLex)). Control bubbles (MB(CTL)) bore surface Lewis(x) or sialyl Lewis(c). Intravital microscopy of mouse cremaster muscle was performed after intravenous injection of MB(sLex) (n=11) or MB(CTL) (n=9) with or without prior intrascrotal tumor necrosis factor-alpha. There was greater adhesion of MB(sLex) to inflamed versus noninflamed endothelium (P = 0.0081). Rats (n=12) underwent 15 minutes of anterior descending coronary artery occlusion. After 30 minutes and 1 hour of reperfusion, high-mechanical-index nonlinear echocardiographic imaging was performed in which single frames were acquired at 3.5 and 4 minutes after intravenous injection of MB(sLex) or MB(CTL). Video intensity at 4 minutes was subtracted from that at 3.5 minutes to derive target-specific acoustic signal. MB(sLex) caused greater opacification in postischemic versus nonischemic myocardium at both time points (P < or = 0.002). Immunostaining confirmed endothelial P-selectin expression in the ischemic bed.. Echocardiographic identification of recently ischemic myocardium is possible using ultrasound contrast agents targeted to selectins. This may offer a new approach to the more timely and precise diagnosis of acute coronary syndrome in patients presenting with chest pain of uncertain cardiac origin.

Topics: Animals; Chest Pain; Contrast Media; Diagnosis, Differential; Echocardiography; Endothelium, Vascular; Microbubbles; Myocardial Ischemia; Myocardial Reperfusion; Myocardium; Oligosaccharides; P-Selectin; Rats; Rats, Inbred Strains; Rats, Wistar; Sensitivity and Specificity; Sialyl Lewis X Antigen; Up-Regulation

1 This study investigated the effects of soluble complement receptor type 1 (sCR1) or sCR1sLex, agents which function as a complement inhibitor or as a combined complement inhibitor and selectin adhesion molecule antagonist, respectively, on the infarct size and cardiac troponin T (cTnT) release caused by regional myocardial ischaemia and reperfusion in the rat. 2 Eighty-two, male Wistar rats were subjected to 30 min occlusion of the left anterior descending coronary artery (LAD) followed by 2 h of reperfusion. Haemodynamic parameters were continuously recorded and at the end of the experiments infarct size (with p-nitro-blue tetrazolium) and cTnT release were determined. 3 Infusion of sCR1 (1, 5 or 15 mg kg-1, each n=7) or sCR1sLe(x) (1, 5 or 15 mg kg-1, n=7, 13 or 13, respectively) 5 min prior to LAD-reperfusion caused a reduction in infarct size from 59+/-2% (PBS - control, n=12) to 46+/-6%, 25+/-9% and 37+/-6% or 42+/-6%, 35+/-6% and 35+/-4%, respectively. 4 Infusion of sCR1 (15 mg kg-1, n=5) or sCR1sLe(x) (15 mg kg-1, n=5) also reduces the myocardial TnT release from 80+/-20 ng ml-1 (control) to 13+/-7 or 4+/-1 ng ml-1, respectively. 5 Thus, sCR1 or sCRsLe(x) significantly reduce infarct size and cardiac TnT release caused by 30 min of regional myocardial ischaemia and 2 h of reperfusion in the rat. The mechanisms of the cardioprotective effects of sCR1 or sCR1sLe(x) are not entirely clear, but may be due complement inhibition and/or prevention of the adhesion and activation of neutrophils.

Topics: Animals; Blood Pressure; Cardiovascular Agents; Glycosylation; Heart Rate; Hemodynamics; Male; Monocytes; Myocardial Infarction; Myocardial Ischemia; Myocardium; Oligosaccharides; Rats; Rats, Wistar; Receptors, Complement; Recombinant Proteins; Sialyl Lewis X Antigen; Troponin T

The role of P-selectin and the ligands of selectins such as sialyl Lewis X and sulfatide was studied in a myocardial ischemia and reperfusion injury model. Anesthetized rabbits underwent the occlusion of coronary artery (30 min) followed by reperfusion (5 h). The inhibitory effect on myocardial ischemia and reperfusion injury was examined with infarct size normalized by area-at-risk. Intravenous administration of an anti-P-selectin monoclonal antibody, PB1.3 (2 mg/kg), reduced infarct size by 38%. Similarly, the administration of sialyl Lewis X-oligosaccharide (10 mg/kg) reduced infarct size by 53% significantly. Finally, the infarct size was significantly reduced bv 39% in sulfatide-treated group (10 mg/kg). These results suggest that P-selectin plays an important role in myocardial ischemia and reperfusion injury and that the ligands of selectins, such as sialyl Lewis X-oligosaccharide and sulfatide, have cardioprotective effect on myocardial ischemia and reperfusion injury.

Topics: Animals; Antibodies, Monoclonal; Leukocyte Count; Ligands; Male; Myocardial Ischemia; Myocardial Reperfusion Injury; Oligosaccharides; P-Selectin; Rabbits; Sialyl Lewis X Antigen; Sulfoglycosphingolipids

Neutrophils (PMNs) are known to contribute to both cardiac dysfunction and myocardial necrosis after reperfusion of an ischemic heart. Moreover, platelets are also important blood cells that can aggravate myocardial ischemic injury. This study was designed to test the effects of PMNs and platelets separately and together in provoking cardiac dysfunction in isolated perfused rat hearts after ischemia and reperfusion.. Control rat hearts not subjected to ischemia were perfused without blood cells for 80 minutes. Additional control rat hearts were perfused with 75x106 PMNs, with 100x106 platelets, or with 75x106 PMNs+100x106 platelets over a 5-minute perfusion followed by a 75-minute observation period. No significant reduction in coronary flow, left ventricular developed pressure (LVDP), or the first derivative of LVDP (dP/dtmax) was observed at the end of the observation period in any nonischemic group. Similarly, global ischemia (I) for 20 minutes followed by 45 minutes of reperfusion (R) produced no sustained effects on the final recovery of any of these parameters in any group of hearts perfused in the absence of blood cells. However, I/R hearts perfused with either PMNs or platelets alone exhibited decreases in these variables of 10% to 12% (P<0.05 from control). Furthermore, I/R hearts perfused with both PMNs and platelets exhibited decreases of 50% to 60% in all measurements of cardiac function (P<0.001). These dual-cell-perfused I/R hearts also exhibited marked increases in cardiac myeloperoxidase (MPO) activity, indicating a significant PMN infiltration, and enhanced P-selectin expression on the coronary microvascular endothelium. All cardiodynamic effects as well as MPO accumulation and PMN infiltration were markedly attenuated by a sialyl LewisX-oligosaccharide or a recombinant soluble P-selectin ligand, which inhibits selectin-mediated cell adhesion.. These results provide evidence that platelets and neutrophils act synergistically in provoking postreperfusion cardiac dysfunction and that this may be largely due to cell-to-cell interactions mediated by P-selectin. These findings may help explain the reperfusion injury phenomenon.

Topics: Animals; Blood Platelets; Cell Communication; Coronary Circulation; Heart; Male; Myocardial Ischemia; Myocardial Reperfusion Injury; Neutrophils; Oligosaccharides; P-Selectin; Peroxidase; Rats; Rats, Sprague-Dawley; Sialyl Lewis X Antigen

Polymorphonuclear leukocytes (PMN) are directly involved in development of ischemic myocardial injury. Adhesion of PMN to endothelial cells is an initial step that triggers a sequential process leading to acute inflammatory responses. Interaction between P-selectin and its oligosaccharide ligand, sialyl Lewis x (sLex), plays an important role in the early stage of the adhesion. To examine the role of P-selectin in various animal disease models especially in rats, we have cloned rat E- and P-selectin cDNAs and established monoclonal antibodies against these rat selectins. In this report, we describe the generation and characterization of anti-rat P-selectin antibodies (ARPs). These antibodies detect cell surface P-selectin on thrombin-stimulated rat platelets. More importantly, intravenous administration of ARP2-4 reduced infarction developed after 30 min of ischemia followed by 24 h of reperfusion in a rat myocardial injury model. In addition, similar protective effect was also observed by administration of a sLex-oligosaccharide. These results indicate that cell adhesion mediated via P-selectin is involved in the development of ischemia and reperfusion injury in rat heart.

Topics: Animals; Antibodies, Monoclonal; Disease Models, Animal; Myocardial Ischemia; Myocardial Reperfusion Injury; Oligosaccharides; P-Selectin; Rats; Sialyl Lewis X Antigen; Superoxide Dismutase

Neutrophils which infiltrate into the myocardial tissue subjected to ischaemia, followed by reperfusion, play a major role in myocardial reperfusion injury. It is known that early rolling attachment of neutrophils is mainly mediated by the selection family of cell-adhesion molecules and that this adhesion is then strengthened through the interaction of integrins and intercellular adhesion molecule-1. To investigate the role of sialyl Lewis(X) (SLe(X)), which is a ligand of all three members of the selections, in myocardial reperfusion injury, the expression of SLe(X) was examined in rat hearts subjected to 30 min of ischaemia followed by reperfusion. The effects were also analysed of in vivo administration of an anti-SLe(X) monoclonal antibody (MAb) on myocardial necrosis in a rat model of myocardial reperfusion injury. Reperfusion of ischaemic myocardial tissue resulted in enhanced expression of SLe(X) on the luminal surface of vascular endothelial cells (VECs), as well as cardiac myocytes. Furthermore, the in vivo administration of an anti-SLe(X) MAb significantly reduced the extent of the myocardial infarction developed after 30 min of ischaemia followed by 48 h of reperfusion. These findings indicate that SLe(X) plays a critical role in the development of myocardial reperfusion injury and offer a potentially useful immune therapy to protect against this injury.

Topics: Animals; Antibodies, Monoclonal; Endothelium, Vascular; Immunoenzyme Techniques; Male; Myocardial Ischemia; Myocardial Reperfusion; Myocardial Reperfusion Injury; Myocardium; Oligosaccharides; Rats; Rats, Wistar; Sialyl Lewis X Antigen

Selectins are important adhesion molecules which utilize a carbohydrate ligand such as sialyl Lewisx (SLex). Our objective was to study the effects of a liposome-conjugated SLex (Lipo-SLex) in myocardial ischaemia (MI) and reperfusion (R) injury in order to further clarify the actions of this carbohydrate.. We studied the efficacy of Lipo-SLex in a feline model of MI (90 min) and R (270 min) injury in vivo. Lipo-SLex (400 micrograms SLex/kg, iv) was administered intravenously 10 min prior to R. We also utilized an in vitro system of neutrophil adherence to thrombin-stimulated coronary endothelium to validate the efficacy of Lipo-SLex.. Lipo-SLex significantly attenuated myocardial necrosis (8.6 +/- 1.2 vs. 29.5 +/- 3.1% of area-at-risk, P < 0.01) and plasma creatine kinase activities (P < 0.01) compared to vehicle (liposome alone). Moreover, endothelium-dependent relaxation to acetylcholine and A23187 in ischaemic-reperfused coronary rings obtained from cats treated with Lipo-SLex was significantly preserved compared to cats given liposomes without SLex (P < 0.01). After reperfusion, ex vivo PMN adherence to ischaemic-reperfused coronary endothelium was significantly increased in vehicle-treated cats, however, this was significantly attenuated in Lipo-SLex-treated cats (82 +/- 7 vs. 28 +/- 3 PMNs/mm2, P < 0.01). Myeloperoxidase activity in the ischaemic myocardium, a marker of PMN accumulation, was also significantly attenuated in Lipo-SLex-treated cats compared to liposomes without SLex (P < 0.01).. Liposome-conjugated SLex-oligosaccharide attenuates myocardial necrosis and preserves coronary endothelial function following MI/R in vivo. The mechanism appears to be mediated by inhibition of the initial PMN-endothelial interaction and eventual accumulation into the ischaemic cardiac tissue. The liposome-SLex complex may be an efficient drug formulation for acute inflammatory diseases.

Topics: Acetylcholine; Animals; Calcimycin; Cats; Cell Adhesion; Creatine Kinase; Drug Carriers; Endothelium, Vascular; In Vitro Techniques; Liposomes; Male; Myocardial Ischemia; Myocardial Reperfusion Injury; Myocardium; Neutrophils; Oligosaccharides; Peroxidase; Sialyl Lewis X Antigen; Thrombin; Vasodilation