Increased expression of neutrophil and monocyte adhesion molecules in unstable coronary artery disease

Monocyte expression of tissue factor and adhesion molecules: the link with accelerated coronary artery disease in patients with chronic renal failure

OBJECTIVE

To investigate the expression of monocyte tissue factor (MTF) and adhesion molecules in patients with chronic renal failure (CRF) and to look for any correlation with thrombin generation and Lp(a) lipoprotein.

DESIGN

A study of MTF expression and adhesion molecules, prothrombin fragments 1+2 (PTf1+2), an index of thrombin generation, and lipoproteins in patients with CRF and in normal control subjects.

BACKGROUND

Patients with end stage renal failure have an increased risk of coronary artery disease despite advances in therapy. Stimulated monocytes are potent activators of blood coagulation through the generation of MTF, which was recently implicated in the aetiology of acute coronary ischaemic syndromes.

METHODS

MTF expression and adhesion molecules were measured in whole blood using immunofluorescence of monocytes labelled with anti-tissue factor antibody and CD11b and c by flow cytometry. PTf1+2 and Lp(a) lipoprotein in plasma were measured by enzyme linked immunosorbent assay (ELISA).

PATIENTS

70 patients with CRF without documented coronary artery disease (30 patients with CRF undialysed, 20 patients undergoing chronic ambulatory peritoneal dialysis (CAPD), and 20 undergoing haemodialysis (HD)), together with 20 normal controls, were studied.

RESULTS

The (mean (SD)) increased MTF of CRF (48.0 (29) v 33.3 (7.2) mesf unit/100 monocytes in controls, p = 0.04) was more pronounced in patients undergoing dialysis (HD 73.1 (32.8) (p < 0.003) and CAPD 62.8 (28.9) mesf unit/100 monocytes, p < 0.04). MTF activity showed a positive correlation with both PTf1+2 and serum creatinine (p < 0.003) but not with Lp(a) lipoprotein. Lp(a) lipoprotein was significantly increased in both dialysis groups compared with controls (p < 0.005) and non-dialysis CRF groups (p < 0.02). Monocyte adhesion molecule (CD11b) was significantly higher in all three CRF groups than in the controls (p = 0.006).

CONCLUSION

This study has demonstrated a hypercoagulable state in patients with CRF. This was especially pronounced in the dialysis patients. These findings provide a possible explanation for the increased cardiovascular and cerebrovascular morbidity and mortality in these patients.

Intense acute phase response in ischemic patients

The aim of this study was to estimate the qualitative and quantitative changes of acute phase proteins in patients suffering from coronary heart disease. The study was carried out on 74 patients and 12 healthy volunteers. The patients were divided into three groups as follows: patients with myocardial infarction (n=37), Group I--without heart failure, Group II--with heart failure (II-III NYHA), Group III--patients with unstable angina pectoris (n=35); controls-healthy volunteers (n=12). The immunological measurements were performed at the beginning of hospitalisation (point 0), after 4, 8, 12 and 72 h, and after 6, 9 and 12 days of hospitalisation. The concentrations of C-reactive protein (CRP), alpha1-acid glycoprotein (AGP) and alpha1-antichymotrypsin (ACT) were measured using rocket immunoelectrophoresis according to Laurell. Glycosylation profiles of AGP and ACT were determined using crossed affinity immunoelectrophoresis with Con A as ligand according to Bøg-Hansen. Between Groups I and II statistically significant differences were observed for all investigated parameters. Highest concentration values were observed for Groups II and III; for Group II they appeared earlier than for Group III. The maximal values for reactivity coefficients (AGP-RC and ACT-RC) were observed earlier than the respective maximal values of concentrations. Continuous activation occurring in unstable angina leads to a more rapid increase in the concentrations of acute phase proteins and more marked alterations in their glycosylation profiles. In a way these patients seem to be 'primed' with constant stimulation, so that they respond dramatically to the stimulus of ischemia.

The effects of iloprost infusion on microcirculation is independent of nitric oxide metabolites and endothelin-1 in chronic peripheral ischaemia

BACKGROUND

Endothelial vascular tone modulators are thought to be involved in aetiopathogenesis of systemic sclerosis (SS) and of peripheral artery occlusive disease (PAOD). Iloprost, a prostacyclin (PGI2) analogue, induces clinical benefit in patients suffering from peripheral ischaemia. This study was performed to investigate the effect of this drug on endothelial function in vivo to elucidate the role of vascular tone modulators.

METHODS

Fourteen PAOD and 15 SS patients were treated for 24 and 10 days respectively. On the first day, before and after therapy, nitric oxide metabolites (NO2-/NO3-) and endothelin-1 (ET-1) plasma concentrations were detected; moreover, the endothelium-dependent vasodilatation in response to artificial ischaemia was evaluated by means of an echo-Doppler device.

RESULTS

The echo-Doppler evaluation showed that the percentage of arterial reactive dilatation was not modified by placebo or by iloprost, and that the increase in blood velocity flow lasted for a significant longer time after drug infusion (226.79 +/- 17.49 vs. 310.71 +/- 36.32 s; P > 0.04). NO2-/NO3- and ET-1 plasma concentration were higher in patients than in control subjects (P < 0.004). After 6 h of iloprost infusion, no significant modifications were detected.

CONCLUSION

This study provides evidence that iloprost enhances the microvascular functional capacity and clinical benefit for patients. The effects of the drug seem to be independently or not directly correlated with its interactions with vascular tone modulators such as NO2-/NO3- or ET-1.

Chimeric 7E3 Fab (ReoPro) decreases detectable CD11b on neutrophils from patients undergoing coronary angioplasty

OBJECTIVES

The purpose of this study was to monitor the effects of chimeric 7E3 Fab (ReoPro) on leukocyte and platelet activation and interaction during coronary angioplasty.

BACKGROUND

Increased expression of CD11b on monocytes and neutrophils promotes their adhesion to endothelial cells, extracellular matrix and smooth muscle cells. Thrombin-activated platelets adhere via P-selectin to monocytes and neutrophils. These cell interactions may affect the outcome of coronary angioplasty.

METHODS

During coronary angioplasty, venous blood was obtained for flow cytometric detection of leukocyte CD11b; platelet CD41a, CD61a and CD62P; the percentage of leukocytes with adherent platelets and the intensity of bound platelet fluorescence.

RESULTS

Leukocyte CD11b expression increased after angioplasty in control patients (neutrophils 171+/-25 to 255+/-31 mean fluorescence intensity [MFI, mean+/-SEM], n=25, p < 0.0001; monocytes 200+/-40 to 248+/-36 MFI, n=17, p < 0.05) and decreased in the patients selected to receive chimeric 7E3 Fab (neutrophils 146+/-30 to 82+/-22 MFI, n=25, p < 0.0001; monocytes 256+/- 53 to 160+/-38 MFI, n= 17, p < 0.05). Neutrophil CD11b decreased after in vitro incubation of whole blood with chimeric 7E3 Fab (n=5, p=0.01), but fMLP-induced increases in CD11b were not prevented. The CD11b expression was unchanged and increased with fMLP stimulation after in vitro incubation of isolated neutrophils with chimeric 7E3 Fab. Direct-labeled chimeric 7E3 Fab was not detected bound to neutrophils in whole blood or isolated cells using flow cytometric techniques. Adhesion of isolated neutrophils to protein-coated glass was not prevented by in vitro incubation with chimeric 7E3 Fab. Platelet activation increased after angioplasty in control patients (CD62P 8.9+/-0.8 to 12.3+/-1.2 MFI, n=25, p < 0.05; CD41a 382+/-25 to 454+/-26 MFI, n=25, p < 0.05, CD61a 436+/-52 to 529+/-58 MFI, n=11, p < 0.05); it did not increase in the patients selected to receive chimeric 7E3 Fab (CD62P 13.2+/-1.0 to 9.0+/-0.9 MFI, n=25, p < 0.05; CD61a 398+/-32 to 410+/-38 MFI, n=7, p=NS). Leukocytes with adherent platelets tended to increase in the control group of patients and decrease after the procedure in patients selected to receive chimeric 7E3 Fab; individual and procedure-related variability were marked.

CONCLUSIONS

Despite standard aspirin and heparin therapy, leukocyte and platelet activation with platelet adherence to leukocytes occurs after coronary angioplasty. Although chimeric 7E3 Fab does not bind to leukocytes directly, it influences CD11b expression in whole blood. Modulation of platelet and leukocyte activation and interaction by chimeric 7E3 Fab may contribute to an improved outcome after coronary angioplasty.

Plasma soluble intercellular adhesion molecule-1 levels in coronary circulation in patients with unstable angina

It has been suggested that active inflammation plays an important role in the pathogenesis of acute coronary syndromes, including unstable angina. Intracellular adhesion molecule-1 (ICAM-1) is a major ligand on the endothelial cells for adherence of the activated polymorphonuclear leukocytes. Recently, it has been demonstrated that the soluble form of ICAM-1 has been detected in human serum and has been increased in many other inflammatory or autoimmune disorders. To evaluate the involvement of ICAM-1 in unstable angina, we examined plasma soluble ICAM-1 (sICAM-1) levels in coronary circulation. The plasma sICAM-1 levels in the coronary sinus and aortic root were simultaneously examined in 20 patients with unstable angina, 19 patients with stable exertional angina, and 16 control subjects. The plasma levels of sICAM-1 were measured by enzyme-linked immunosorbent assay. The mean plasma sICAM-1 levels (nanograms per milliliter) both in the coronary sinus and aortic root were significantly higher (p <0.01) in patients with unstable angina than in those with stable exertional angina and in control subjects (217+/-14 vs 126+/-8; 120+/-10 in the coronary sinus, 202+/-13 vs 125+/-9; 123+/-10 in the aortic root). Furthermore, the mean value was higher in the coronary sinus than in the aortic root in patients with unstable angina. There were no significant differences in the values between in the coronary sinus and aortic root in patients with stable exertional angina and control subjects. Thus, sICAM-1 release is increased, especially in coronary circulation in unstable angina.

Is vasculitis a significant component of atherosclerosis?

Although atherosclerosis was linked to infections many decades ago, only recently there has been a renewed interest to study this association further. These research endeavors have provided a substantial amount of knowledge concerning the mechanisms that may link inflammation, immunity, and infections to the molecular and cellular events in the arterial wall leading to atherosclerotic lesions.

Myocardial ischemia-reperfusion injury in CD18- and ICAM-1-deficient mice

Previous studies have demonstrated that circulating neutrophils (PMNs) contribute to the pathophysiology of myocardial ischemia-reperfusion (MI/R) injury. PMN-endothelial cell interactions are highly regulated by adhesive interactions between PMN CD11/CD18 and coronary endothelial cell intercellular adhesion molecule-1 (ICAM-1). We investigated the effects of MI/R in wild-type, CD18-, and ICAM-1-deficient (-/-) mice. Wild-type (n = 6), CD18 -/- (n = 6), and ICAM-1 -/- (n = 6) mice were subjected to 30 min of myocardial ischemia and 120 min of reperfusion to determine the extent of PMN infiltration and myocardial cell necrosis. Myocardial infarction (% of the area at risk) was 45.1 +/- 5.9 in wild-type mouse hearts. In contrast, the extent of myocardial infarction was significantly (P < 0.05) reduced in the CD18 (19.3 +/- 5.1%)- and ICAM-1 (17.9 +/- 3.2%)-deficient mice. Similarly, PMN infiltration into the ischemic-reperfused myocardium was attenuated by 54% in the CD18 -/- mice and by 32% in ICAM-1 -/- mice compared with wild-type hearts. Deficiency in either CD18 or ICAM-1 expression results in a marked reduction in PMN accumulation and myocardial necrosis after acute MI/R.

Immune system activation follows inflammation in unstable angina: pathogenetic implications

OBJECTIVES

The aim of this study was to assess the relations between inflammation, specific immune response and clinical course in unstable angina (UA).

BACKGROUND

Several studies suggest that either inflammation and/or T-cell activation might have a pathogenetic role in UA, but neither their potential reciprocal connection nor their relation to the clinical course is known.

METHODS

Serum levels of C-reactive protein (CRP) (inflammation), IgG, IgA, IgM, C3, C4 (humoral immunity), IL-2 and the percentage of CD4+, CD8+ and CD3+/DR+ T-cells (cell-mediated immunity) were measured in 35 patients with UA and 35 patients with chronic stable angina (CSA) during a period of 6 months.

RESULTS

The CRP levels and the main specific immune markers (CD4+ and CD3+/DR+ cells, IL-2 and IgM) were higher in unstable than in stable angina. In UA, the serum levels of IgM and IL-2 and the percentage of double positive CD3+/DR+ significantly increased at 7 to 15 days, and returned to baseline at 6 months. The increment of circulating activated T cells (CD3+/ DR+) in UA was inversely related to the admission levels of CRP (r=-0.63, p=0.003) and associated with a better outcome.

CONCLUSIONS

Our data suggest that the inflammatory component systemically detectable in UA may be antigen-related and that the magnitude of the immune response correlates with the clinical outcome of instability.

Prognostic implications of detection of troponin I in patients with unstable angina pectoris

In our study, troponin I was not a predictor of cardiac events and a negative troponin I test did not exclude the presence of severe coronary artery disease. A positive troponin I test in patients with unstable angina identified a subgroup with probable, more active coronary disease (with higher levels of C-reactive protein).

Chlamydia pneumoniae: inflammation and instability of the atherosclerotic plaque

Coronary heart disease remains the most common cause of death in industrialized countries. Although atherosclerosis is generally asymptomatic in the early stages, progressive plaque development leads to arterial stenosis which is characterized by angina and may eventually lead to unstable angina, myocardial infarction and cardiac death. Evidence that the coagulation cascade is activated during acute coronary events has justified the use of antithrombotic agents such as aspirin, heparin and low molecular weight heparin (LMWH) in the standard management of acute coronary syndromes. The inflammatory process is also known to play a significant role in the pathogenesis of atherosclerosis, resulting in a cycle of continued inflammatory cell activation and ongoing cell recruitment. As the human leukocyte-associated antigen (HLA) system plays a key role in the regulation of the inflammatory process, the expression of HLA antigens in patients with symptomatic coronary heart disease has been investigated. These studies have demonstrated a relationship between the major histocompatibility complex (MHC) class II expression and the most severe pattern of angina refractory to conventional therapy, within the framework of a chronic infectious disease. A number of studies have documented an association between coronary heart disease and the presence of high titres of antibodies to Chlamydia pneumoniae, and this organism has been implicated in plaque instability. Such findings have stimulated interest in the role of C. pneumoniae in the pathogenesis of coronary heart disease, with a view to developing novel and effective treatment approaches. The ROXIS study showed a lower incidence of acute ischaemic events in patients with unstable angina treated with an antichlamydial antibiotic, roxithromycin.

Rationale for the management of coronary syndromes with low-molecular-weight heparins

The well-documented disadvantages of unfractionated heparin in the management of coronary syndromes, such as unpredictable bioavailability and maintenance of therapeutic range, has prompted several studies into the benefits of low-molecular-weight heparins (LMWHs). The favorable pharmacologic properties of LMWHs include a binding affinity for antithrombin III, anti-factor IIa activity, excellent bioavailability, minimal protein binding, predictable anticoagulant response, and clinical tolerance by patients. LMWHs are also characterized by having a specific anti-factor Xa effect and inducing only a small prolongation in general clotting tests-i.e., activated partial thromboplastin time, prothrombin time, and antithrombin activity-when used in high doses. Several studies have recently demonstrated that LMWHs are superior to placebo and are at least equal or superior to standard heparin when added to aspirin for the treatment of unstable angina and following non-Q-wave myocardial infarction. These studies, which include Thrombolysis in Myocardial Infarction (TIMI) 11A and Efficacy and Safety of Subcutaneous Enoxaparin versus intravenous unfractionated heparin in Non-Q-wave Coronary Events (ESSENCE), will be reviewed and discussed.

Soluble adhesion molecules in reperfusion during coronary bypass grafting

OBJECTIVE

Adhesion of activated leukocytes to the endothelial cells as a result of myocardial ischaemia/reperfusion during open chest coronary artery surgery has been shown to be involved in the development of tissue damage. Activated leukocytes adhere to endothelium via adhesion molecules expressed by both cell types, resulting in the impairment of coronary capillary flow. Upon cell activation, adhesion proteins may be released in the soluble form to circulating blood. The purpose of our study was to verify whether myocardial ischaemia/reperfusion occurring during coronary artery bypass grafting results in release of the soluble adhesion molecules VCAM-1, ICAM-1, E-selectin and L-selectin into the circulation.

METHODS

Plasma levels of the soluble adhesion molecules were measured in vein, arterial and coronary sinus blood samples taken from 15 patients undergoing coronary artery bypass grafting (CABG). Blood samples for estimations were collected during the procedure: before aorta cross-clamping, at the beginning of reperfusion and 30 min after reperfusion. Soluble adhesion molecules levels were measured by standard ELISA assays.

RESULTS

Mean plasma levels of soluble VCAM-1 in arterial samples increased significantly at the beginning of reperfusion and 30 min after reperfusion. In contrast, soluble L-selectin plasma levels in arterial samples remained unchanged. In coronary sinus samples, levels of soluble ICAM-1 significantly increased 30 min after reperfusion. Moreover, in coronary sinus samples collected 30 min after reperfusion, soluble ICAM-1 levels were significantly higher than in arterial samples obtained at the same time. The mean concentration of soluble E-selectin in samples obtained from coronary sinus decreased significantly 30 min after reperfusion. Moreover, plasma levels of soluble E-selectin in coronary sinus samples obtained 30 min after reperfusion were significantly decreased compared with these observed in arterial samples collected at the same time.

CONCLUSIONS

The reperfusion of ischaemic myocardium during CABG results in a significant increase in plasma levels of the soluble endothelial adhesion molecules VCAM-1 and ICAM-1 and significant decrease in soluble E-selectin plasma levels. L-selectin plasma levels during CABG procedure remain unchanged. We propose that the increased plasma concentrations of soluble VCAM-1 and ICAM-1 are a result of endothelial cell activation during ischaemia/reperfusion following bypass surgery.

Interactive role of infection, inflammation and traditional risk factors in atherosclerosis and coronary artery disease

Although first suggested at the turn of the 20th century, there is a renewed interest in the infectious theory of atherosclerosis. Studies done in many laboratories around the world over the past several years have shown an association between markers of inflammation and coronary atherosclerosis with an exacerbation of the inflammatory process during acute myocardial ischemia, particularly in the early stages of reperfusion. It is also being recognized that the traditional risk factors, such as smoking, dyslipidemia, hypertension and diabetes mellitus, do not explain the presence of coronary atherosclerosis in a large proportion of patients. We believe that in certain genetically susceptible people, infection with very common organisms, such as Chlamydia pneumoniae or cytomegalovirus, may lead to a localized infection and a chronic inflammatory reaction. Persistence of infection may relate to the degree of inflammation and severity of atherosclerosis. Early trials with appropriate antibiotic agents in some patients with a recent history of acute myocardial infarction have led to very salutary results. If patients with an infectious basis of atherosclerosis can be identified, a therapy directed at eradication of the offending organism may be appropriate.

Cell adhesion molecules in cardiovascular disease: a clinical perspective

In summary, there is increasing evidence that cell adhesion molecules play an important role in cardiovascular pathology. They are involved in the main processes that underlie cardiac disease including thrombosis, leucocyte infiltration, smooth muscle proliferation, and cell migration. Anti-integrin treatment is already widely used to treat thrombotic complications, and it seems likely that manipulation of other cell adhesion molecules will be used clinically in the near future.

Effect of trans-resveratrol, a natural polyphenolic compound, on human polymorphonuclear leukocyte function

1. Polymorphonuclear leukocytes (PMN) may contribute to the pathogenesis of acute coronary heart disease (CHD). 2. Epidemiological and laboratory evidence suggests that red wine, by virtue of its polyphenolic constituents, may be more effective than other alcoholic beverages in reducing the risk of CHD mortality. 3 The aim of the present study was to investigate the effects of trans-resveratrol (3,4',5-trihydroxy-trans-stilbene), a polyphenol present in most red wines, on functional and biochemical responses of PMN, upon in vitro activation. 4. trans-Resveratrol exerted a strong inhibitory effect on reactive oxygen species produced by PMN stimulated with 1 microM formyl methionyl leucyl phenylalamine (fMLP) (IC50 1.3+/-0.13 microM, mean+/-s.e.mean), as evaluated by luminol-amplified chemiluminescence. 5. trans-Resveratrol prevented the release of elastase and beta-glucuronidase by PMN stimulated with the receptor agonists fMLP (1 microM, IC50 18.4+/-1.8 and 31+/-1.8 microM), and C5a (0.1 microM, IC50 41.6+/-3.5 and 42+/-8.3 microM), and also inhibited elastase and beta-glucuronidase secretion (IC50 37.7+/-7 and 25.4+/-2.2 microM) and production of 5-lipoxygenase metabolites leukotriene B4 (LTB4), 6-trans-LTB4 and 12-trans-epi-LTB4 (IC50 48+/-7 microM) by PMN stimulated with the calcium ionophore A23187 (5 microM). 6. trans-Resveratrol significantly reduced the expression and activation of the beta2 integrin MAC-1 on PMN surface following stimulation, as revealed by FACS analysis of the binding of an anti-MAC-1 monoclonal antibody (MoAb) and of the CBRM1/5 MoAb, recognizing an activation-dependent epitope on MAC-1. Consistently, PMN homotypic aggregation and formation of mixed cell-conjugates between PMN and thrombin-stimulated fixed platelets in a dynamic system were also prevented by transresveratrol. 7. These results, indicating that trans-resveratrol interferes with the release of inflammatory mediators by activated PMN and down-regulates adhesion-dependent thrombogenic PMN functions, may provide some biological plausibility to the protective effect of red wine consumption against CHD.

Elevated circulating levels of C-C chemokines in patients with congestive heart failure

BACKGROUND

Immunologic and inflammatory responses appear to play a pathogenic role in the development of congestive heart failure (CHF). Activation and migration of leukocytes to areas of inflammation are important factors in these immunologic responses. Because the C-C chemokines are potent chemoattractants of monocytes and lymphocytes and can modulate other functions of these cells (eg, generation of reactive oxygen species), we measured circulating levels of three C-C chemokines in CHF.

METHODS AND RESULTS

Levels of macrophage chemoattractant protein-1 (MCP-1), macrophage inflammatory protein- 1alpha (MIP-1alpha), and RANTES (regulated on activation normally T-cell expressed and secreted) were measured by enzyme immunoassays in 44 patients with CHF and 21 healthy control subjects. CHF patients had significantly elevated levels of all chemokines with the highest levels in New York Heart Association class IV, and MCP-1 and MIP-1alpha levels were significantly inversely correlated with left ventricular ejection fraction. Elevated C-C chemokine levels were found independent of the cause of the heart failure, but MCP-1 levels were particularly raised in patients with coronary artery disease. Studies on cells isolated from peripheral blood suggested that platelets, CD3+ lymphocytes, and in particular, monocytes, might contribute to the elevated C-C chemokine levels in CHF. The increased MCP-1 levels in CHF were correlated with increased monocyte activity reflected in an enhancing effect of serum from CHF patients on O2-generation in monocytes, which was inhibited by neutralizing antibodies against MCP-1.

CONCLUSIONS

This first demonstration of increased circulating levels of C-C chemokines in CHF with particularly high levels in patients with severe disease may represent previously unrecognized pathogenic factors in CHF.

Increased expression of neutrophil and monocyte adhesion molecules LFA-1 and Mac-1 and their ligand ICAM-1 and VLA-4 throughout the acute phase of myocardial infarction: possible implications for leukocyte aggregation and microvascular plugging

OBJECTIVES

This study sought to evaluate expression of adhesion molecules on neutrophils and monocytes throughout the acute phase of myocardial infarction.

BACKGROUND

Neutrophil and monocyte counts increase within days from onset of acute myocardial infarction. Because leukocytes are recruited to the involved myocardial region, we postulated that these activated cells would display an increased expression of adhesion molecules necessary for effective endothelial transmigration.

METHODS

We measured the expression of neutrophil and monocyte lymphocyte function associated antigen-1 (LFA-1), Mac-1, very late after activation antigen-4 (VLA-4) and intercellular adhesion molecule-1 (ICAM-1) by flow cytometry throughout the acute phase of acute myocardial infarction in 25 patients and 10 age-matched control subjects.

RESULTS

Expression of Mac-1 on neutrophils increased significantly, whereas no expression of VLA-4 and ICAM-1 was detected. The expression of LFA-1, Mac-1, VLA-4 and ICAM-1 on the monocyte cell membrane in patients with an acute myocardial infarction was increased compared with that in control subjects by 22% (on day 7), 67%, 13% and 44% (all on day 4), respectively (all p < 0.001). Elevated density of monocyte-specific CD14 in the AMI versus the control group was also shown (30%, p < 0.001).

CONCLUSIONS

Increased expression of neutrophil and monocyte adhesion molecules may contribute to their adhesion to endothelium in the ischemic territory. This adhesion could feasibly precipitate vasoconstriction or add a local thrombotic effect due to tissue factor expression secondary to Mac-1 engagement. In addition, the manifestation of increased density of LFA-1 and Mac-1 by activated leukocytes with monocytes also expressing ICAM-1 suggests that leukocytes may form microaggregates that could cause microvascular plugging. This mechanism may facilitate the occurrence of the "no-reflow" phenomenon or slow coronary filling after acute myocardial infarction.

Host tissue damage by phagocytes

Evidence continues to accumulate on the importance of neutrophils (PMNs) and phagocytes in the causation of tissue and endothelial injury that frequently accompanies the inflammatory response. Increased production of superoxide anions in combination with decreased endothelial antioxidant activity may contribute to the development of vascular disease including atherosclerosis, vasospasm, diabetic vascular complications, tissue damage in ischemia-reperfusion, and hypotension. Free radicals generated in the vascular wall may act directly on smooth muscle or interact with each other thus producing biologically active endogenous mediators. Derangement of macrophage function may occur in conditions characterized by protein malnutrition, thus leading to failure to develop a specific immunoresponse and to an increase in the production of oxygen intermediate radicals, which may cause tissue damage. A local inflammatory response followed by endothelial cell activation could also facilitate migration of immunocompetent cells into the parenchyma of grafted organs and stimulate dendritic cells in the graft. There is now convincing evidence that excessive and prolonged production of NO contributes to tissue damage in septicemia, ischemia/reperfusion injury, and other inflammatory conditions. There is also increasing evidence that the complement system plays an important role in tissue damage in association with phagocytes, e.g., in ischemia/reperfusion injury, carcinogenesis, and aging. It can therefore be surmised that phagocytic cells may act both as "friends" and as "foes" and that they are important mediators of tissue damage in a variety of conditions.

C-reactive protein elevation and early outcome in patients with unstable angina pectoris

C-reactive protein, a reactant of the acute phase of inflammation, has been shown to be increased in patients with unstable angina. Moreover, it has recently been found that increased C-reactive protein is associated with a poor outcome during hospitalization in selected patients with severe unstable angina. The aim of this study was to investigate the prognostic value of C-reactive protein elevation in a large population with unstable angina. We measured serum levels of this marker in 140 patients hospitalized with unstable angina (class IIIB of the Braunwald classification, mean time from last anginal episode 5 +/- 5 hours). Thirty-nine of them (28%) had increased serum levels on hospital admission and 33 (24%) experienced an adverse outcome (myocardial infarction or refractory angina) during hospitalization. Kaplan-Meier analysis showed that the probability of developing cardiac events during hospitalization was not different between patients with and without abnormal C-reactive protein levels. Furthermore, the incidence of ischemia at Holter monitoring during the first 72 hours after hospitalization was not different between patients with and without abnormal C-reactive protein. In a representative population of patients with unstable angina, a sizable proportion had increased serum C-reactive protein levels; however, abnormal concentrations of C-reactive protein do not predict an adverse outcome in the early phase after the acute episode.

Priming of neutrophils after elective percutaneous transluminal coronary angioplasty is unrelated to accompanying brief myocardial ischemia

OBJECTIVE

The purpose of this study was to investigate the effect of brief myocardial ischemia and vascular trauma induced by elective percutaneous transluminal coronary angioplasty on in vivo 'priming' and activation of neutrophils.

PATIENTS AND METHODS

We studied 16 patients undergoing elective coronary angioplasty for symptomatic coronary artery disease and a control group of seven patients undergoing diagnostic cardiac catheterization. Free radical production from purified neutrophils (Ficoll-Hypaque density gradient method) was measured indirectly by the chemiluminescence method. Myocardial ischemia during balloon inflation was assessed by serial lactate determinations from coronary sinus and arterial blood. The degree of transient angioplasty-related myocardial ischemia was related to the oxidative response of activated neutrophils.

RESULTS

Mean (+/-S.E.M.) oxidative response, i.e. the lucigenin- and luminol-enhanced-chemiluminescence (counts per minute) of neutrophils sampled from the coronary sinus increased significantly after percutaneous transluminal coronary angioplasty (Lucigenin-chemiluminescence: pre-angioplasty 3.69+/-0.64x10(5) vs. post-angioplasty 7.08+/-1.2x10(5), P<0.01; Luminol-chemiluminescence: pre-angioplasty 2.81+/-0.67x10(6) vs. post-angioplasty 5.2+/-0.92x10(6), P<0.01). Twelve of 16 patients developed transient cardiac lactate production (mean coronary sinus lactate excess: +0.12 mmol/l) and three disclosed a lactate extraction ratio <10%, both suggestive of myocardial ischemia. However, there was no correlation between the cardiac lactate production and the increased oxidative response after coronary angioplasty (r2 (Lucigenin-chemiluminescence)=0.02, n.s.; r2 (Luminol-chemiluminescence)=0.06, n.s.).

CONCLUSION

'Priming' of neutrophils, as reflected by increased oxidative response, is likely to occur after coronary angioplasty, but not after the angiographic procedure itself. However, 'priming' seems to be unrelated to the transient brief period of myocardial ischemia and rather depends on an alternative mechanism.

Juxtalumenal location of plaque necrosis and neoformation in symptomatic carotid stenosis

PURPOSE

The structural features that underlie carotid plaque disruption and symptoms are largely unknown. We have previously shown that the chemical composition and structural complexity of critical carotid stenoses are related to plaque size regardless of symptoms. To further determine whether the spatial distribution of individual plaque components in relation to the lumen corresponds to symptomatic outcome, we evaluated 99 carotid endarterectomy plaques.

METHODS

Indications for operation were symptomatic disease in 59 instances (including hemispheric transient ischemic attack in 29, stroke in 19, and amaurosis fugax in 11) and angiographic asymptomatic stenosis > 75% in 40. Plaques removed after remote symptoms beyond 6 months were excluded. Histologic sections from the most stenotic region of the plaque were examined using computer-assisted morphometric analysis. The percent area of plaque cross-section occupied by necrotic lipid core with or without associated plaque hematoma, by calcification, as well as the distance from the lumen or fibrous cap of each of these features, were determined. The presence of foam cells, macrophages, and inflammatory cell collections within, on, or just beneath the fibrous cap was taken as an additional indication of plaque neoformation.

RESULTS

The mean percent angiographic stenosis was 82% +/- 11% and 79% +/- 13% for the asymptomatic and symptomatic groups, respectively (p > 0.05). The necrotic core was twice as close to the lumen in symptomatic plaques when compared with asymptomatic plaques (0.27 +/- 0.3 mm vs 0.5 +/- 0.5 mm; p < 0.01). The percent area of necrotic core or calcification was similar for both groups (22% vs 26% and 7% vs 6%, respectively). There was no significant relationship to symptom production of either the distance of calcification from the lumen or of the percent area occupied by the lipid necrotic core or calcification. The number of macrophages infiltrating the region of the fibrous cap was three times greater in the symptomatic plaques compared with the asymptomatic plaques (1114 +/- 1104 vs 385 +/- 622, respectively, p < 0.009). Regions of fibrous cap disruption or ulceration were more commonly observed in the symptomatic plaques than in the asymptomatic plaques (32% vs 20%). None of the demographic or clinical atherosclerosis risk factors distinguished between symptomatic and asymptomatic plaques.

CONCLUSIONS

These findings indicate that proximity of plaque necrotic core to the lumen and cellular indicators of plaque neoformation or inflammatory reaction about the fibrous cap are associated with clinical ischemic events. The morphologic complexity of carotid stenoses does not appear to determine symptomatic outcome but rather the topography of individual plaque components in relation to the fibrous cap and the lumen. Imaging techniques that precisely resolve the position of the necrotic core and evidence of inflammatory reactions within carotid plaques should help identify high-risk stenoses before disruption and symptomatic carotid disease.

The release of soluble adhesion molecules ICAM-1 and E-selectin after acute myocardial infarction and following coronary angioplasty

Endothelial cells express surface adhesion molecules for leukocytes in response to myocardial ischaemia. These molecules may be released into plasma by activated cells and be detectable in soluble form. Samples were collected from the peripheral vein of 14 consecutive patients with acute myocardial infarction (AMI) at the time of admission, 6 h, and 1 and 5 days post-admission. Additionally, samples were drawn from the coronary sinus ostium and peripheral artery of seven patients undergoing coronary angioplasty (PTCA) before and after the first balloon inflation. We measured the plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1) and soluble E-selectin (sELAM-1). In patients with AMI plasma levels of sICAM-1 exceeded those observed in age and sex-matched healthy subjects, (mean+/-SEM; 220.6+/-18 ng/ml) at all the time intervals assessed (358.9+/-24.5; 330.9+/-24.4; 379.4+/-39.7 and 366.8+/-47.5 ng/ml, respectively, p<0.01). sELAM-1 levels, however, were normal on admission, increased at 6 h to 52.7+/-3.8 ng/ml, p<0.05, and at day 1 (56.0+/-4.6 ng/ml) before decreasing to normal levels on the fifth day. After brief myocardial ischaemia occurring during PTCA, an increased level of sICAM-1 was observed following balloon deflation in the coronary sinus (329.2+/-20 ng/ml; p<0.05) as compared to the subjects undergoing coronary angiography, but not in the peripheral artery. sELAM-1 levels remained unchanged during angioplasty. Thus, soluble adhesion molecules expressed by activated endothelial cells are released into peripheral blood during both AMI and brief myocardial ischaemia and measurement of such molecules may prove useful for monitoring vascular endothelium activation following myocardial ischaemia/necrosis.

Role of inflammation in the pathogenesis of unstable coronary artery disease

In this article, the clinical, angiographic, and postmortem features of unstable angina are reviewed and its pathogenesis is discussed. Coronary plaque inflammation may play a key role in the pathogenesis of unstable angina and the evidence for this assertion is examined. Finally, the therapeutic implications of the involvement of inflammation in acute coronary syndromes are outlined.

Increased plasma soluble intercellular adhesion molecule-1 levels in patients with acute myocardial infarction

Intercellular adhesion molecule-1 (ICAM-1) is a major ligand for 2 members of the CD18 family of leukocyte integrin adhesion molecules and mediates adhesion between leukocytes and stimulated endothelial cells. We examined plasma soluble ICAM-1 (sICAM-1) levels in 30 patients with acute myocardial infarction (AMI) within 6 h of symptom onset, 21 patients with unstable angina (UA), 35 patients with stable exertional angina (SEA) and 21 control subjects. Plasma sICAM-1 levels (ng/ml) were significantly higher in both the acute and chronic phases of AMI and in the UA group than in the SEA and the control groups (195 +/- 14, 198 +/- 16 in the acute and chronic phases of AMI, 188 +/- 11 in the UA group vs 142 +/- 7 in the SEA group, 141 +/- 10 in the control group, p < 0.01). Plasma sICAM-1 levels were significantly higher in AMI patients when preceded by unstable angina than when not preceded by unstable angina at any point over the time course except 1 week after admission (p < 0.01 vs admission, 12 h, 2 days, 3 days, 5 days, 2 weeks, 3 weeks. p < 0.05 vs 24 h). These results suggest that the increase in sICAM-1 is associated with repeated episodes of myocardial ischemia and reperfusion not leading to myocardial necrosis. The increase in sICAM-1 may play an important role as an inflammatory component in the pathogenesis of the ischemic myocardium.

Changes in the polymorphonuclear leukocyte function of blood samples induced by storage time, temperature and agitation

We have investigated changes in polymorphonuclear leukocyte (PMN) functions of blood samples caused by such typical elements of laboratory handling as storage time, temperature and agitation. The blood of five healthy subjects was stored upright in test tubes at 4, 22 and 37 degrees C over periods of 20 min, one, two, six and 24 h. Controlled agitation was performed on a shaker. The following PMN functional parameters were measured: the white blood cell count (WBC), migration, elastase (EL) release, reactive oxygen species (ROS) production and lipid peroxidation. Migration was determined in a whole-blood membrane filter assay; ROS production by latex-stimulated, luminol-enhanced chemiluminescence (CL) in a whole-blood assay; EL as EL alpha 1-antitrypsin complex; and lipid peroxidation by malondialdehyde (MDA) generation. The reactions after handling were compared with the values measured immediately after blood withdrawal which served as reference values of 'genuine' PMN reactivity. The outstanding result was the marked scatter between the individual reactions. Overall, the proportion of migrating PMNs in the blood total decreased, while CL, correlating positively with MDA, increased with the time of storage. EL increased considerably in some of the samples. Agitation raised CL and MDA. The effect of temperature was apparent only after 24 h at 37 degrees C. There was evidence that inhomogeneities in the blood samples were another interfering factor, since resuspension of sedimented blood after storage can be incomplete. In order to obtain reliable results from PMN functional tests, whole-blood assays and processing of blood samples within 20 min after blood withdrawal are recommended.

Levels of expression of P-selectin, E-selectin, and intercellular adhesion molecule-1 in coronary atherectomy specimens from patients with stable and unstable angina pectoris

Unstable angina occurs when atherosclerotic plaque ruptures. Recent evidence suggests a role for inflammation in this process. Leukocyte-endothelial cell interactions are important in inflammation and are regulated by cell adhesion molecules. This study was designed to examine the vascular expression of cell adhesion molecules and cytokines in patients with unstable angina. Directional coronary atherectomy was performed in patients with unstable and stable angina. Expression of the cell adhesion molecules P-selectin, E-selectin, and intercellular adhesion molecule-1 in the tissue obtained was examined using immunohistochemistry. In addition, expression of the cytokines tumor necrosis factor-alpha and interleukin-1beta, which participate in the regulation of cell adhesion molecule expression, was also examined. Atherectomy specimens had significantly greater P-selectin expression from patients with unstable angina than from patients with stable angina. P-selectin expression was observed primarily on endothelial cells. There were no differences in any of the other factors between patients with unstable and stable angina. In addition, other clinical and angiographic variables were not associated with differential expression of any of the cell adhesion molecules or cytokines. These results indicate a possible role for P-selectin in the process of unstable angina.

Megakaryocytes and platelets in vascular disease

Platelets are anucleate cells with no DNA. They are derived from their precursor, the megakaryocyte (MK), whose differentiation is characterized by nuclear polyploidization through a process called endomitosis. Changes in the MK-platelet-haemostasis axis may precede acute thrombotic events. Changes in MK ploidy distribution may be associated with the production of large platelets. Mean platelet volume (MPV) is an important biological variable as it is a determinant of platelet reactivity. Large platelets are denser and more active haemostatically. MPV is increased in patients after myocardial infarction (MI) and is a predictor of a further ischaemic event and death when measured after MI. It has been suggested that changes not only in platelets but also in the parental MK are associated with chronic and acute vascular events. The regulation of megakaryocytopoiesis depends on several haematopoietic factors such as thrombopoietin. An understanding of the signalling system that controls platelet number and size might give insight into a role of platelet production in thrombogenesis and atherogenesis.

Expression of polymorphonuclear leukocyte adhesion molecules and its clinical significance in patients treated with percutaneous transluminal coronary angioplasty

OBJECTIVES

This study evaluated the role of neutrophil adhesion molecules LFA-1 (CD11a/CD18), Mac-1 (CD11b/CD18) and p150,95 (CD11c/CD18) in patients undergoing percutaneous transluminal coronary angioplasty (PTCA).

BACKGROUND

Several recent studies have suggested that cell adhesion molecules on both neutrophils and vascular endothelial cells play an important role in the process of tissue inflammation.

METHODS

Thirty-eight patients (30 men, 8 women; mean [+/-SE] age 56 +/- 5 years, range 38 to 76) with single-vessel coronary artery disease of the left anterior descending artery underwent coronary angioplasty. Peripheral blood was sampled at baseline before, immediately after and 12, 24, 48 and 144 h after PTCA. The expression of CD18, CD11a, CD11b and CD11c on the surface of polymorphonuclear leukocytes was examined by flow cytometry with monoclonal antibodies.

RESULTS

In patients without subsequent restenosis, there was no change in mean channel fluorescence intensity (MFI) of CD18 at each sampling time. However, in the patients with restenosis, the MFI of CD18 significantly increased at 48 h after PTCA (from 57 +/- 6 to 73 +/- 8, p = 0.0008). The MFI of CD11b increased slightly at 48 h after PTCA in patients without restenosis (from 584 +/- 121 to 735 +/- 114, p = 0.037). In patients with restenosis, the MFI of CD11b was slightly increased at 24 h after PTCA (from 586 +/- 122 to 768 +/- 214, p = 0.018) and significantly increased at 48 h after PTCA (to 1,534 +/- 268, p = 0.0006). The expression of CD11a and CD11c did not change at any sampling points after PTCA in either of the two patient groups. Percent change in the expression of CD18 at 48 h after PTCA (from baseline) and that of CD11b were correlated (r = 0.73, p = 0.0008) in patients with restenosis.

CONCLUSIONS

Inflammatory stimuli within the coronary vessels associated with coronary angioplasty may upregulate Mac-1 expression on the surface of polymorphonuclear leukocytes. This process may be more marked in patients who experience later restenosis. Thus, activation of neutrophil adhesion molecule Mac-1 at 48 h after PTCA may have value as a predictor of subsequent restenosis.

Iloprost effects on phagocytes in patients suffering from ischaemic diseases: in vivo evidence for down-regulation of alpha M beta 2 integrin

This study has been designed to demonstrate the in vivo effects of iloprost therapy on expression of adhesion molecules on phagocytes. Sixty patients suffering from peripheral arterial occlusive disease (PAOD) and/or from skin ulcers due to secondary progressive systemic sclerosis (PSS) were enrolled in a double-blind controlled parallel study. Thirty patients (group I) underwent iloprost infusion and 30 patients (group II) were treated with aspirin. Clinical assessment and measurement of phagocyte activation in vivo, using quantitative flow cytometry, were performed on entry and after 6 h on the first day of therapy. After 3 months of therapy, complete healing of all cutaneous lesions was observed in 84% of the patients treated with iloprost compared with the control patients (P < 0.001). Neutrophils and monocytes of PAOD and PSS patients showed a significant decrease in the expression of the alpha M beta 2 integrin adhesion receptor after 6 h of iloprost infusion. Neutrophils and monocytes released a lower amount of anion superoxide (O2-) after 6 h of iloprost treatment. These data confirm other clinical observations but demonstrate that in vivo this drug modifies the expression of the alpha M beta 2 integrin of phagocytes that has a key role in leukocyte-endothelium interactions in cases of inflammation and thrombosis.

Expression of neutrophil and monocyte CD11B/CD18 adhesion molecules at different sites of the coronary tree in unstable angina pectoris

To assess the site of leukocyte activation in unstable angina, the expression of neutrophil and monocyte CD11B/CD18 adhesion molecules in 26 patients was measured from blood samples taken from the coronary ostium, the coronary sinus, and the coronary artery just distal to the culprit lesion (postobstructive chamber). CD11B/CD18 adhesion molecules detected by direct immunofluorescence evaluated by flow cytometry were significantly higher in the coronary sinus blood than in both the coronary ostium and the postobstructive chamber blood, suggesting that leukocyte activation takes place at the microcirculatory interface with the injured myocardium, probably as the result of short but repeated episodes of myocardial ischemia.

Leukocyte activation with platelet adhesion after coronary angioplasty: a mechanism for recurrent disease?

OBJECTIVES

The purpose of this pilot study was to determine whether leukocyte activation occurs, whether leukocyte-platelet complexes develop and whether there is any association between these findings and clinical outcome after coronary angioplasty.

BACKGROUND

Increased expression of CD11b on monocytes and neutrophils promotes their adhesion to endothelial cells, extracellular matrix and smooth muscle cells. Thrombin-activated platelets adhere to monocytes and neutrophils through P-selectin. These cell complexes may affect the inflammatory process and, thus, the outcome of coronary angioplasty.

METHODS

During elective single-vessel coronary angioplasty in 11 men, samples were obtained for flow cytometric detection of CD11b, as well as the percent of leukocytes with adherent platelets and the intensity of bound platelet fluorescence (number of platelets/leukocyte).

RESULTS

After angioplasty, there was an increase in CD11b (monocytes: p = 0.001, neutrophils: p = 0.02) and leukocytes with adherent platelets (p = 0.02). During follow-up, five patients remained in stable condition and six had subsequent clinical events: restenosis and progression of disease requiring coronary artery bypass grafting (n = 3), myocardial infarction involving the dilated artery (n = 1) and unstable angina (n = 2). Values for leukocyte CD11b expression, the percent of leukocytes with adherent platelets and the intensity of bound platelet fluorescence were higher both before and after angioplasty in the six patients experiencing clinical events.

CONCLUSIONS

Despite standard aspirin and heparin therapy, leukocyte activation with platelet adherence occurs after coronary angioplasty. The magnitude of leukocyte activation and platelet adherence appears to be higher in patients experiencing late clinical events.

Alterations in circulating intercellular adhesion molecule-1 and L-selectin: further evidence for chronic inflammation in ischemic heart disease

Atherosclerosis is increasingly thought to be a chronic inflammatory disease. Inflammation requires transmigration of leukocytes from the circulation to the tissues. Adhesion of leukocytes to endothelial calls is the initial event in an inflammatory response and is mediated by expression of several adhesion molecules. In this study we characterize the contribution of intercellular adhesion molecules (ICAM-1) and L-selectin in patients with different coronary artery disease syndromes. Serum concentrations of cICAM-1 and sL-selectin were measured by enzyme-linked immunosorbent assay in 31 patients with stable angina, 30 patients with unstable angina, 18 patients with acute myocardial infarction and 20 healthy subjects in a control group. All patients underwent coronary angiography. Mean (+/-SE) cICAM-1 levels were higher (p < 0.05) in patients with stable angina (249 +/- 6 ng/ml), unstable angina (260 +/- 16 ng/ml), or acute myocardial infarction (261 +/- 24 ng/ml) compared with those in subjects in the control group (171 +/- 11 ng/ml). In contrast, levels of sL-selectin were lower (p < 0.01) in patients with stable angina (1.2 +/- 0.1 microg/ml), unstable angina (1.1 +/- 0.6 microg/ml), or acute myocardial infarction (1.1 +/- 0.1 microg/ml) compared with those in subjects in the control group (1.8 +/- 0.1 microg/ml). No difference was found in cICAM-1 or sL-selectin levels among patients with stable angina, unstable angina, or acute myocardial infarction. No correlation was seen between cICAM-1 or sL-selectin levels and extent (or severity) of coronary artery disease or leukocyte count. L-selectin expression was observed to be depressed in patients with severe angina compared with that in members of the control group. To examine the mechanism of reduction in sL-selectin levels and L-selectin expression on leukocytes, leukocytes from the control group were stimulated in vitro. Stimulation of leukocytes resulted in a rapid downregulation of surface L-selectin expression, measured by flowcytometry, similar to the suppressed expression of L-selectin found on leukocytes from patients with coronary artery disease. In conclusion, altered cICAM-1 and sL-selectin levels in patients with coronary artery disease reflect the presence of a chronic inflammatory process. This inflammatory process results in downregulation of leukocyte expression of L-selectin and thus lower circulating sL-selectin levels.

Increased plasma levels of B-type natriuretic peptide in patients with unstable angina

This study was designed to examine the plasma levels of B-type or brain natriuretic peptide (BNP), as well as A-type or atrial natriuretic peptide (ANP) in patients with unstable angina as compared with those in patients with stable exertional angina and control subjects. We measured the plasma levels of BNP and ANP in 33 patients with unstable angina, 20 patients with stable exertional angina, and 20 control subjects. The plasma levels of BNP were significantly increased in patients with unstable angina compared with those in patients with stable exertional angina and control subjects, respectively (39.5 +/- 29.4 pg/ml vs 15.1 +/- 8.0 pg/ml; p < 0.01 and 39.5 +/- 29.4 pg/ml vs 10.3 +/- 6.4 pg/ml; p < 0.01, respectively). On the other hand, there was no significant difference in the plasma levels of ANP among the three groups. Furthermore, in patients with unstable angina, the plasma levels of BNP decreased significantly after the medical treatment (from 39.5 +/- 29.4 pg/ml to 15.8 +/- 11.0 pg/ ml; p < 0.01), whereas the plasma levels of ANP did not change. We conclude that the plasma levels of BNP are increased in the majority of patients with unstable angina and that the increased levels decrease toward normal after treatment.

Circulating intercellular adhesion molecule-1 and E-selectin in patients with acute coronary syndrome

To characterize the role of circulating intercellular adhesion molecules (ICAM-1) and E-selectin in patients with acute coronary syndrome, serum levels of ICAM-1 and E-selectin were measured by enzyme-linked immunosorbent assay (ELISA). Group 1 comprised 17 patients with acute myocardial infarction; group 2 included 17 patients with unstable angina; and group 3 included 19 control subjects. These 53 patients all had prolonged chest pain within 24 h and all underwent coronary angiography. Group 1 and 2 patients had significant coronary artery disease, while group 3 had normal coronary arteries. Blood samples were collected at the emergency department before antiplatelet agents were given. Serum levels of 1CAM-1 were higher in group 1 and 2 (383 +/- 27 and 337 +/- 11 ng/mL, respectively) as compared with group 3 (282 +/- 18 ng/mL) (group 1 vs 3, p<0.01; group 2 vs 3, p<0.05). The serum levels of ICAM-1 were not significantly different between group 1 and 2. Serum levels of E-selectin in group 1, 2, and 3 were 58 +/- 8, 51 +/- 4, and 58 +/- 5 ng/mL, respectively. The serum levels of E-selectin showed no significant difference among the three groups. In conclusion, serum levels of ICAM-1 were elevated in patients with acute coronary syndrome within 24 h, while the E-selectin levels did not change significantly. This finding suggests that adhesion molecule may play an important role in the postrolling process of leukocyte-endothelial cell interaction in acute coronary syndrome.

Pathophysiology and inflammatory aspects of plaque rupture

Atherosclerotic plaque disruption with superimposed thrombosis is the main cause of acute coronary events. At present it is not known specifically how various risk factors influence the development and configuration of coronary plaques. The risk of plaque disruption depends more on plaque composition and vulnerability (plaque type) than on the degree of stenosis (plaque size). Lipid accumulation and chronic inflammation, particularly macrophage activities, seem to influence the development and the stability of a plaque and thus its propensity to rupture. Macrophages have the ability to secrete proteolytic enzymes and often infiltrate the region of imminent plaque rupture, and disruption may be associated with a generalized inflammatory reaction. Further, plaque disruption tends to occur at points where the plaque surface is weakest, corresponding to locations where mechanical and hemodynamic forces have their highest impact. The risk of plaque disruption is a function of both plaque vulnerability (intrinsic disease) and rupture triggers (extrinsic forces). The former predisposes the plaque to rupture; the latter may precipitate rupture. The danger of vulnerable plaques, however, is not related to disruption as such but to the resulting thrombosis. The magnitude of this thrombotic response and the ensuing flow obstruction depends on the contents and quantity of exposed thrombogenic plaque material, the degree of pre-existing stenosis, and the systemic thrombotic tendency. The thrombotic response is a dynamic process that is decisive for the clinical presentation and the outcome.

Atherosclerotic plaque rupture in symptomatic carotid artery stenosis

PURPOSE

Plaque rupture is often the precipitating event in acute coronary syndromes. We hypothesized that a similar process occurs in stenotic carotid plaques in association with ischemic neurologic symptoms. Our purpose was to examine several morphologic features of stenotic carotid plaques and to determine which characteristics are more commonly associated with plaques obtained from patients with symptomatic carotid artery disease than with those from patients with asymptomatic carotid artery disease.

METHODS

Forty-four carotid endarterectomy specimens (from 25 asymptomatic and 19 symptomatic patients) were analyzed with pentachrome staining and light microscopy. The asymptomatic patients and symptomatic patients had similar mean percent stenosis (77% vs 74%). Other risk factors, including hypertension, diabetes mellitus, coronary artery disease, smoking history, serum cholesterol, and triglyceride levels, were similar between groups.

RESULTS

Patients with symptomatic carotid artery disease were found to have more frequent plaque rupture, fibrous cap thinning, and fibrous cap foam-cell infiltration when compared with the asymptomatic group. Plaque rupture was seen in 74% of symptomatic plaques and in only 32% of plaques from asymptomatic patients (p = 0.004). Fibrous cap thinning was noted in 95% of symptomatic plaques and in 48% of asymptomatic plaques (p = 0.003). Infiltration of the fibrous cap with foam cells was also significantly more common in the symptomatic plaques (84% vs 44% of asymptomatic plaques; p = 0.006). In addition, intraplaque fibrin was more common in symptomatic plaques than in asymptomatic (100% vs 68%; p = 0.008). No significant differences were found between the two groups with respect to plaque hemorrhage, the presence of a necrotic core, luminal thrombus, smooth muscle cell infiltration, eccentric shape, and plaque type (fibrous, necrotic, or calcified).

CONCLUSIONS

As in the coronary artery system, rupture of the atherosclerotic plaque may play an important role in the pathogenesis of ischemic stroke caused by carotid artery stenosis. The process of inflammation, involving foam-cell infiltration of the fibrous cap, may contribute to rupture of the atherosclerotic plaque.

Association of plasma fibrinogen levels with coronary artery disease, smoking and inflammatory markers

The plasma level of fibrinogen is associated with the risk of ischaemic heart disease (IHD) and the severity of atherosclerosis. It has been suggested that an increased plasma level of fibrinogen is a coronary risk indicator because it reflects the inflammatory condition of the vascular wall. An inflamed vascular wall may increase the production of the cytokines interleukin 6 (IL6), interleukin 1-beta (IL1-beta), and tumour necrosis factor alpha(TNF-alpha), which have a major role in the regulation of synthesis in the liver of acute phase proteins, including fibrinogen. Smoking has also been reported to increase the levels of fibrinogen and C-reactive protein (CRP). This may indicate that smoking induces an inflammatory reaction, probably of the pulmonary bronchi and alveolae. Therefore, we anticipated that with both types of inflammation the levels of acute phase proteins and cytokines would be related. We have investigated the contribution of inflammation to the plasma levels of fibrinogen in 34 patients with severe coronary artery disease (CAD) and 30 healthy controls comparable for age and smoking habits. We did not find a parallel in the effects of smoking and ischaemic heart disease on the plasma levels of fibrinogen, CRP, IL6, IL1-beta and TNF-alpha. Cardiovascular disease had its most important effect on the plasma fibrinogen level, while smoking appeared to increase the CRP levels, while both CAD and smoking seemed to affect the IL6 levels. Our results indicate that both smoking and CAD induce an inflammatory condition but that the increase of plasma levels of different inflammatory markers is complex. Although the acute phase reaction is the main regulatory mechanism of fibrinogen, the increase of fibrinogen in our group of CAD patients could not be fully explained by increased inflammation.

Intracellular neutrophil myeloperoxidase is reduced in unstable angina and acute myocardial infarction, but its reduction is not related to ischemia

OBJECTIVES

This study sought to assess neutrophil activation in acute coronary syndromes and its relation to ischemic episodes.

BACKGROUND

Neutrophil activation has been reported in unstable angina and acute myocardial infarction; however, it is not clear whether it is related exclusively to ischemia-reperfusion injury.

METHODS

We measured the index of intracellular myeloperoxidase in 1) patients with unstable angina, myocardial infarction, variant angina and chronic stable angina and in normal subjects (protocol A); and 2) in patients with unstable angina and acute myocardial infarction during the first 4 days of the hospital period (protocol B). To assess whether neutrophil activation was triggered by ischemia, the myeloperoxidase intracellular index was analyzed before and after spontaneous ischemic episodes and before and after ischemia induced by an exercise stress test in 10 patients with chronic stable angina. In 11 patients with unstable angina, we also compared values of the myeloperoxidase intracellular index at entry with those after waning of symptoms.

RESULTS

In protocol A, the myeloperoxidase intracellular index was significantly reduced in patients with unstable angina and acute myocardial infarction compared with patients with stable and variant angina and normal subjects (p < 0.01). In protocol B, the myeloperoxidase intracellular index did not change over time in patients with unstable angina and myocardial infarction. However, in 11 patients with waning symptoms, the myeloperoxidase intracellular index was significantly higher afer symptoms had waned (p < 0.05). In patients with unstable angina, 23 ischemic episodes were studied; no changes in the myeloperoxidase intracellular index were observed. In 10 patients with chronic stable angina and positive exercise stress test results, no significant differences in the myeloperoxidase intracellular index were observed after stress-induced ischemia.

CONCLUSIONS

Our study confirms that neutrophils are activated in acute coronary syndromes but suggests that their activation may not be only secondary to ischemia-reperfusion injury.

Potentiation of human polymorphonuclear leukocyte activation by atrial natriuretic peptide. Inhibitory effect of carnitine congeners

Polymorphonuclear leukocytes (PMN), atrial natriuretic peptide (ANP) and leukotriene B4 (LTB4) reportedly play a major role in ischemia/reperfusion states of coronary artery disease. We sought to determine whether ANP and LTB4 cooperate in inducing PMN activation with consequent modulation of membrane molecules required for adherence to endothelium and myocardial cells, namely CD11b and L-selectin and the release of toxic oxygen radicals. ANP (from 10(-16) to 10(-8) M), LTB4 (from 10(-10) to 10(-6) M) and combinations of the two were incubated with normal PMN at 37 degrees C for 15 minutes. Membrane molecules modulation was measured by flow cytometry using specific monoclonal antibodies. Hydrogen peroxide production, an indicator of the capacity of PMN to release toxic oxygen species was quantified by flow cytometry using the peroxide-sensitive fluorescent probe dichlorofluorescein diacetate. ANP, uneffective when used alone, dose-dependently potentiated the PMN response to LTB4 (10(-9) M) as evidenced by an up-regulation of CD11b expression and peroxide production, and a down-regulation of L-selectin expression. These effects were prevented dose-dependently by the protein kinase C (PKC) inhibitor staurosporine (from 10 to 160 microM). Two carnitine congeners, palmytoylcarnitine (tested from 125 pg to 2 micrograms/ml) that also possesses an established ability to antagonise PKC and L-carnitine (tested from 12 to 200 ng/ml) were also effective. These data indicate that ANP potentiates LTB4 in inducing PMN mobilization and activation with a possible consequent detrimental effect on cardiac tissue and evisages the usefulness of PMN metabolism modulators.

Chronic treatment with interleukin-1 beta induces coronary intimal lesions and vasospastic responses in pigs in vivo. The role of platelet-derived growth factor

Studies in vitro have suggested that inflammatory cytokines may play an important role in the pathogenesis of atherosclerosis. However, little is known about their effects in vivo. Thus, the present study was designed to determine in vivo what histological and functional changes may be induced by chronic treatment with IL-1 beta, one of the major inflammatory cytokines, and also to clarify what mechanisms are involved in those changes. Under aseptic conditions, proximal segments of the left porcine coronary arteries were gently wrapped with cotton mesh absorbing Sepharose beads either with or without recombinant human IL-1 beta. From 1 to 4 wk after the operation, coronary vasospastic responses to intracoronary serotonin or histamine were noted at the IL-1 beta-treated site but not at the control site. Histologically, intimal thickening was greater at the IL-1 beta-treated site than at the control site. Those functional and histological changes induced by the chronic treatment with IL-1 beta were significantly inhibited by the simultaneous treatment with a neutralizing antibody to either IL-1 beta or PDGF. These results indicate that chronic treatment with Il-1 beta induces coronary intimal lesions and vasospastic responses in porcine coronary arteries in vivo and also suggest that these changes are substantially mediated by PDGF.

Episodic activation of the coagulation system in unstable angina does not elicit an acute phase reaction

The results of our study suggest that the acute phase response may be partly related to a yet unknown primary inflammatory component in unstable angina. Further studies are needed to elucidate the actual role of inflammation in unstable angina and its relation to activation of the coagulation system.

Quantification of leukocyte migration: improvement of a method

Eighteen different permeable membrane supports with and without confluent endothelial cell monolayers were incubated with normal donor derived neutrophils in the upper chambers of a 24 multiwell double chamber system. In order to study transmembrane or transendothelial leukocyte migration leukocytes were stimulated by chemoattractants, or endothelial cells were activated by IL-1. After coincubation the membrane supports building the upper chambers were discarded. Using this technique, leukocytes that had migrated into the lower chamber were exposed to the fluorescent dye calcein AM without additional washing or transfer steps. Absolute cell counts were determined computer assisted using dilution series of calcein AM labeled leukocytes as standards. Serial dilutions of neutrophils exposed to calcein AM showed reproducible linear fluorescence intensity, and relative fluorescence intensity correlated significant with cell counts (r2 = 0.974, p < 0.0001). Out of 18 membrane supports only one was suitable for our assay set up. Best technical and optical performance was achieved with a membrane made of polyethylene terephtalate with a pore size of 3 mm at a pore density of 0.8 x 10(6)/cm2. Stimulation of leukocytes or endothelium by FMLP or IL-1 revealed an increase of transendothelial migration to 7.2 +/- 1.8 x 10(5) PMN and 5.1 +/- 0.7 x 10(5) PMN respectively if compared with medium (0.6 +/- 0.2 x 10(5) PMN). IL-1 induced migration of neutrophils was inhibited by anti IL-1 autoantibodies derived from chronic renal failure patients (IL-1: 100% of PMN migrated, anti IL-1 antibody: 39% of PMN migrated, control antibody: 84% of PMN migrated). In summary, a simple fluorimetric assay was established for the quantification of transmembrane and transendothelial leukocyte migration.