Effect of GPIIb/IIIa inhibition with eptifibatide or tirofiban on the expression of cellular adhesion molecules on monocytes.

AIM: The aim of the present study was to investigate the effect of GPIIb/IIIa inhibition with eptifibatide and tirofiban on the expression of cellular adhesion molecules on monocytes at different temperatures. MATERIALS AND METHODS: Circulation of blood from six volunteers was performed in an extracorporal circulation model at 36°C and 18°C for 30 min. The blood of each donor was prepared either with addition of eptifibatide or tirofiban, or was left untreated as control. CD54 and CD162 on monocytes was measured using flow cytometry. RESULTS: Expression of CD11b was lower at 18°C compared to 36°C by 51% in the eptifibatide group (p=0.0043), by 29% in the tirofiban group (p=0.095) and by 34% in the control group (p=0.038). Expression of CD54 was not significantly different at 18°C compared to 36°C, neither with eptifibatide (p=0.29) nor tirofiban (p=0.48) nor in the control group (p=0.26). Expression of CD162 was lower at 18°C compared to 36°C by 40% using eptifibatide (p=0.0010), by 94% using tirofiban (p=0.0095) and by 34% in the control group (p=0.019). At 36°C and 18°C, no significant differences were found regarding the expression of CD11b, CD54 and CD162 between the eptifibatide-treated group, the tirofiban-treated group and the control group. CONCLUSION: GPIIb/IIIa inhibition with eptifibatide or tirofiban seems to have no effect on the expression of CD11b, CD54 and CD162 on monocytes during normothermia or hypothermia. Our results show that the beneficial effect induced by hypothermia on the extracorporal circulation-associated alteration of leukocyte function, with decreased expression of CD11b and CD162, seems not to be affected by additional treatment with eptifibatide or tirofiban.

Expression of CD11b (MAC-1) and CD162 (PSGL-1) on monocytes is decreased under conditions of deep hypothermic circulatory arrest.

Deep hypothermic circulatory arrest (DHCA) is a common technique used to protect vital organs during surgical interventions on the thoracic aorta or during surgery for complex congenital heart disease. Activated leukocytes are key mediators of inflammatory responses during ischemia. Intercellular crosstalk between leukocytes, platelets and endothelial cells is mediated by cell adhesion molecules. These molecules trigger complex cell-cell interaction mechanisms and initiate the release of proinflammatory molecules. One parameter that is known to have a significant impact on inflammatory cell activation and the production of proinflammatory markers is temperature. However, to the best of our knowledge, no data have yet been published on the effect of hypothermia on leukocyte surface markers during DHCA. Thus, the aim of the present study was to investigate the effect of hypothermia on the expression of cell adhesion molecules on monocytes under DHCA conditions in vitro. Blood samples collected from 11 healthy volunteers were incubated in a well-established model simulating circulatory arrest at 36°C and 18°C for 30 min. The expression of cluster of differentiation (CD) molecule 11B (CD11b), CD54 and CD162 on monocytes was measured as the mean fluorescence intensity (MFI) using flow cytometry. The expression level of CD11b on monocytes was significantly decreased following the incubation of the blood samples at 18°C compared with the level in blood samples incubated at 36°C (P<0.001). After 30 min of blood stasis in the circulatory arrest model, the expression level of CD162 on monocytes was significantly lower in the blood samples incubated at 18°C than in those incubated at 36°C (P<0.001). No association was identified between temperature and the surface expression of CD54 on monocytes following 30 min of stasis. These findings demonstrate that deep hypothermia decreases the expression of CD11b and CD162 on monocytes in an experimental setup simulating the conditions of DHCA. This may be the result of the inhibition of leukocyte-endothelial and leukocyte-platelet interactions, which may be a beneficial aspect of deep hypothermia that affects the inflammatory response and tissue damage during DHCA.

Hypothermia inhibits expression of CD11b (MAC-1) and CD162 (PSGL-1) on monocytes during extracorporeal circulation.

AIM: The aim of the present study was to investigate the effect of different hypothermic temperatures on the expression of cellular adhesion molecules on leukocytes. MATERIALS AND METHODS: Circulation of blood from six volunteers was performed in an extracorporeal circulation model at 36°C, 28°C and 18°C for 30 minutes. Expression of CD11b, CD54 and CD162 on monocytes was measured using flow cytometry. RESULTS: Expression of CD11b significantly decreased at 18°C and at 28°C compared to 36°C. A significant reduction of CD162 expression was found at 18°C compared to 28°C and 36°C and at 28°C compared to 36°C. No association was found between temperature and expression of CD54. CONCLUSION: Expression of CD11b and CD162 on monocytes has a temperature-dependent regulation, with decreased expression during hypothermia, which may result in an inhibition of leukocyte-endothelial and leukocyte-platelet interaction. This beneficial effect may influence the extracorporeal circulation-related inflammatory response and tissue damage.

Thrombogenicity of sirolimus-eluting stents and bare metal stents: evaluation in the early phase after stent implantation.

BACKGROUND: Thrombogenicitiy of drug-eluting stents is a matter of controversial debate. The aim of this study was to evaluate the thrombogenicity of sirolimus-eluting stents (SES) compared to bare metal stents (BMS) in a standardised in vitro model. MATERIALS AND METHODS: Nine SES and nine BMS were implanted in tubing loops and nine loops without stent served as controls. Initially and after 90 minutes of blood circulation in a modified chandler loop model, thrombin-antithrombin III complex (TAT), PMN-elastase, factor XIIa, SC5b-9, sP-selectin and platelet count were measured. Expression of CD62P, CD45/41 and PAC-1 on platelets were determined by flow cytometry. RESULTS: After 90 minutes, platelet count decreased significantly in the loops with BMS and SES (p<0.05). Levels of TAT, PMN-elastase and SC5b-9 were significantly elevated after 90 minutes in all loops (p<0.05). sP-selectin significantly increased in the loops with BMS and SES after 90 minutes. No significant changes occurred in any flow cytometric data. Platelet count, sP-selectin, TAT, PMN-elastase, SC5b-9, CD62P, CD41/CD45 and PAC-1 showed no significant difference between BMS and SES. CONCLUSION: These data provide evidence that there is no difference in thrombogenicity of BMS and SES in the in vitro model.

Effect of clopidogrel on adhesion molecules, hemostasis, and fibrinolysis in coronary heart disease.

BACKGROUND: The interaction among inflammation, Hemostasis, and fibrinolysis plays a major role in the genesis of coronary artery disease (CAD). The aim of the study was to compare the effect of clopidogrel plus aspirin versus aspirin alone on cellular adhesion molecules on leukocytes, soluble adhesion molecules, and molecular markers of coagulation and fibrinolysis in patients with CAD. METHODS: In this randomized, placebo-controlled, and double-blind study, 42 patients with chronic angina pectoris were included. All patients were treated with aspirin (ASA). Twenty-three patients received clopidogrel additionally (75 mg/day with a 300-mg loading dose) for 14 days. Nineteen patients received placebo additionally. Soluble adhesion molecules (sICAM-1, sVCAM-1, sP-selectin), surface expression of CD54, CD11a, CD11b, CD40, CD40L, CD41, CD42b, and CD62L on lymphocytes, monocytes, and neutrophils, and markers of hemostasis and fibrinolysis (TAT, PAP, D-dimers) were measured. RESULTS: In the ASA + clopidogrel group, no change in surface expression of cellular adhesion molecules on leukocytes and on plasma levels of sICAM-1, sVCAM-1, sP-selectin, TAT, PAP, and D-dimers was detectable. CONCLUSIONS: Clopidogrel plus aspirin for 2 weeks did not result in a detectable benefit versus sole aspirin therapy regarding cellular adhesion molecules on leukocytes, plasma markers of coagulation, fibrinolysis, and soluble adhesion molecules in patients with CAD.

Significance of the endothelin ETA receptor in the haemodynamic and inotropic effects of endothelin-1 in rats.

The main aim of the present study was to investigate the direct inotropic effects of stimulation of the endothelin (ET) receptor ETA under in vivo conditions. It is well known that ETA receptor stimulation causes pronounced vasoconstriction. The ET-1-induced coronary vasoconstriction may lead to myocardial ischaemia and, consequently, to cardiodepressor effects that may mask the direct positive inotropic effect of ETA receptor stimulation. Thus, in the present study, steps were taken to avoid this possibility. In anaesthetized open-chest rats the haemodynamic and inotropic effects of ETA receptor stimulation were studied by monitoring responses evoked by ET-1 (1 nmol/kg of body weight) after ETB receptor blockade with BQ 788 (0.5 micromol/kg of body weight); these responses were compared with saline controls (after ETB receptor blockade). To avoid vasoconstrictor effects induced by ETA receptor stimulation, additional experiments were performed in the presence of the vasodilator adenosine (2.0 mg.kg(-1) of body weight.min(-1)). Myocardial function was also examined during aortic clamping so as to circumvent the effect of changes in afterload. We studied further the effect of ETA receptor stimulation on myocardial energy metabolism. ETA receptor stimulation reduced cardiac output (-49% compared with control), raised total peripheral resistance (+173%) and reduced myocardial ATP content (-23%). Aortic clamping did not reveal a positive inotropic effect of ETA receptor stimulation. Furthermore, even though adenosine attenuated the decrease in cardiac output (-21%), the increase of total peripheral resistance (+48%) and prevented the fall of myocardial ATP content (+6%), this did not unmask a positive inotropic effect of ETA receptor stimulation. Thus we conclude that ETA receptor stimulation causes vasoconstriction and myocardial ischaemia, but has no positive inotropic effects in rats.

Relationship between minor myocardial damage and inflammatory acute-phase reaction in acute coronary syndromes.

BACKGROUND: In severe acute coronary syndromes (ACS) elevation of markers of inflammation and acute phase reaction (APR) like C-reactive protein (CRP) as well as a release of troponin have been reported. Using a high sensitivity troponin T (TnT) test we investigated whether an APR occurs in ACS only in the presence of ischemic myocardial damage. METHODS: In 85 patients with ACS C-reactive protein (CRP), serum amyloid A (SAA), fibrinogen, thrombin antithrombin III complexes (TAT) and kallikrein were determined vs. high sensitive TnT (> or =0.02 ng/ml) initially and 2 d later vs. 45 patients with stable angina pectoris and 42 controls. RESULTS: In stable angina pectoris, markers of inflammation and coagulation were slightly elevated (p < 0.05). Initially in ACS elevations of CRP to 1.2 +/- 0.3 mg/dl, SAA to 4.8 +/- 2.6 mg/dl and fibrinogen to 448 +/- 21 mg/dl (all p < 0.01 vs. controls) were found followed by a significant APR (p < 0.01). In the subgroup of TnT positive ACS patients, an APR with increased CRP (4.1 +/- 1.3 mg/dl), SAA (20.4 +/- 8.3 mg/dl), and fibrinogen (641 +/- 45 mg/dl) was detectable (all p < 0.05 vs. TnT negative patients). In contrast, patients without TnT release showed APR markers comparable to patients with stable angina pectoris. CONCLUSION: Our findings demonstrate an association between myocardial injury in ACS and acute phase reaction as evidenced by several molecular markers. A highly sensitive TnT-test identified myocardial injury in about all patients with APR while a standard TnT cut-off (0.1 ng/ml) missed 32% of these patients. Thus, the APR in patients with ACS is strongly associated with at least minor ischemic myocardial damage and prior findings of an APR independent from myocardial injury are probably based on less sensitive troponin tests.

ET(A) receptor blockade improves post-ischaemic functional recovery in 'hibernating' rat myocardium.

Endothelin-1 (ET-1) is a potent vasoconstrictor, and ET(A) receptors mainly mediate this effect. Elevated plasma levels of ET-1 are observed in patients with coronary heart disease. The release of this peptide from the damaged endothelium may play a role in the initiation and maintenance of myocardial ischaemia. This study examines the ET(A) receptor-mediated role of endogenous ET-1 in post-ischaemic myocardial function after prolonged hypoperfusion in normal non-failing hearts. In an isolated rat heart model for short-term myocardial hibernation, left ventricular functional recovery after 3 h of hypoperfusion (15% of pre-ischaemic flow) followed by 2 h of reperfusion was determined. Under steady-state conditions, coronary flow, left ventricular pressure (LVP) and dP/dt(max) were measured in the isovolumically beating heart. Additionally, the maximal inotropic response (LVP and dP/dt(max)) to calcium stimulation was determined. To study the role of ET(A) receptors under these pathophysiological conditions, one group was treated with the ET(A) antagonist BQ 610 (0.8 micromol/l) during hypoperfusion, and compared with a control group which received a saline infusion during hypoperfusion. Reperfusion for 2 h after 3 h of hypoperfusion resulted in partial functional recovery in both groups. Post-ischaemic recovery was significantly better in the hearts that were treated with the ET(A) antagonist BQ 610 during hypoperfusion (LVP, +19.5% compared with control; dP/dt(max), +13.7% compared with control). The inotropic response to calcium was nearly normalized after ET(A) blockade. Thus the normal non-failing myocardium profits from ET(A) receptor blockade during a prolonged period of hypoperfusion, resulting in significantly better post-ischaemic recovery of myocardial function.

Comparison of C-reactive protein and terminal complement complex in patients with unstable angina pectoris versus stable angina pectoris.

Elevated C-reactive protein (CRP) can identify patients with coronary artery disease who are prone to future acute events. We investigated whether elevated CRP is related to the activation of the terminal complement cascade in 66 patients with unstable angina pectoris (UAP), in 45 patients with stable angina pectoris, and in 42 controls. CRP, additional acute phase reactants, the terminal complement complex (sC5b-9), leukocytes, and troponin T were measured. In 47 patients with UAP the CRP values were regarded as elevated (>0.3 mg/dl). In patients with UAP and elevated CRP, the plasma levels of sC5b-9 were markedly higher than in patients with UAP and lower CRP (245 +/- 14 vs 188 +/- 19 ng/ml, p <0.02) and in patients with stable angina pectoris with slightly (0.4 +/- 0.1 mg/dl) increased CRP (sC5b-9 173 +/- 21 vs 130 +/- 7 ng/ml [controls; p <0.05]). A further acute phase reaction was present only in patients with UAP and elevated CRP already on admission (p <0.01). sC5b-9 was not related to troponin release. Thus, elevated CRP levels are associated with activation of the plaque destabilizating terminal complement system in patients with UAP during the acute phase reaction. This may explain the prognostic value of CRP in acute coronary syndromes (ACS).