Increased secretion of tumor necrosis factor-alpha and interferon-gamma by mononuclear leukocytes in patients with ischemic heart disease. Relevance in superoxide anion generation

The therapeutic effect of natriuretic peptides in heart failure; differential regulation of endothelial and inducible nitric oxide synthases

The abnormal regulation of nitric oxide synthase activity represents an underlying feature of heart failure. Increased peripheral vascular resistance, and decreased renal function may be in part related to impaired endothelium-dependent nitric oxide (NO) synthesis. Paradoxically, the chronic production of NO by inducible nitric oxide synthase (iNOS) in heart failure exerts deleterious effects on ventricular contractility, and circulatory function. Consequently, pharmacologically improving endothelium-dependent NO synthesis and the concomitant inhibition of iNOS activity would be therapeutically advantageous. Interestingly, natriuretic peptides have been shown to differentially regulate endothelial NOS (eNOS) and iNOS activity. Moreover, in both patients and animal models of heart failure, pharmacologically increasing plasma natriuretic peptide levels ameliorated vascular tone, renal function, and ventricular contractility. Based on these observations, the following review will explore whether the therapeutic benefit of the natriuretic peptide system in heart failure may occur in part via the amelioration of endothelium-dependent NO synthesis, and the concomitant inhibition of cytokine-mediated iNOS expression.

Arrhythmogenic and inotropic effects of interferon investigated in perfused and in vivo rat hearts: influences of cardiac hypertrophy and isoproterenol

Although the arrhythmogenic effects of interferon (IF) have been reported in clinical practice, the experimental data are limited. Therefore, these effects were investigated in in vivo and Langendorff-perfusion studies using 3 different groups of rats (ie, control, aorta-banded, and deoxycorticosterone acetate (DOCA)-salt hypertension groups) in the presence or absence of isoproterenol. In the perfusion study, human recombinant IF-alpha (< or =15,000 U/ml) alone induced irreversible atrioventricular blockade in all groups, whereas this agent (< or =1,500 U/ml) caused negative inotropism and ventricular tachyarrhythmias (arrhythmic score greater in the order of DOCA-salt>aorta-banded = control group) in the preparations pretreated with isoproterenol (10(-9) mol/L). In an in vivo study, IF-alpha (6x10(6) U/kg) resulted in ventricular tachyarrhythmias only in the presence of isoproterenol (10 mg/kg), as in the perfusion study (arrhythmic score; DOCA-salt>aorta-banded>control). In conclusion, the arrhythmogenesis of IF-alpha is potentiated in pathophysiological conditions such as cardiac hypertrophy or elevated sympathetic activity.

The relation of aggression, hostility, and anger to lipopolysaccharide-stimulated tumor necrosis factor (TNF)-alpha by blood monocytes from normal men

Aggression, hostility, and anger significantly predict morbidity and mortality from atherosclerotic cardiovascular disease (ACVD). ACVD is believed to be an inflammatory disease characterized by increased expression of a number of proinflammatory cytokines, such as tumor necrosis factor (TNF)-alpha. This study examined the relation of aggression, hostility, and anger to monocyte-associated TNF-alpha expression following lipopolysaccharide (LPS) stimulation. Participants were 62 healthy, non-smoking men (aged 18-45 years). Hostility, anger, verbal, and physical aggression were assessed using the Buss-Perry aggression questionnaire (BPAQ). LPS-stimulated TNF-alpha expression was determined using dual-color flow cytometry gating for CD14(+) cells. After controlling for age, race, education, and alcohol use, scores on the hostility (p=.013), physical aggression (p=.010), and verbal aggression (p=.034) subscales, and the total score (p=.007) on the BPAQ were positively associated with LPS-stimulated TNF-alpha expression. The results suggest that hostility and aggression are associated with an increased expression of TNF-alpha, a cytokine implicated in ACVD.

Oxidative stress and neutrophil activation—the two keystones of ischemia/reperfusion injury

The widespread introduction of fibrinolytics and recently also PTCA in the treatment of myocardial infarction has changed the picture of modern cardiology. But this therapy also raises new problems and challenges. One of them is the occurrence of extensive tissue injury caused by reperfusion. Reinstitution of oxygen to the ischemic tissues initiates various processes leading to generation of reactive oxygen species (ROSs). Acting on the plasma membrane ROS damage its organization and release various proinflammatory agents. Different proteins, including receptors, ionic channels, transporters or components of transduction pathways are substrates of oxidation by ROSs. Their changed structure results in altered functioning and disruption of vital cellular processes. Another key factor of reperfusion injury is activation and infiltration of infarcted area by polymorphonuclear leukocytes (PMNs). Multiple studies identified consecutive stages of PMN activation and substances being involved in it. Main interest lies in cellular adhesion molecules, particularly selectins and beta2 integrins, as their antagonists were repeatedly found to diminish neutrophil activation and infarct size. Nevertheless new publications strike at the foundations of the established order and confront the relation between neutrophil infiltration and infarct size. PMNs are linked by close ties to other cells involved in inflammatory response. Seemingly also in cardiac ischemia-reperfusion injury, the activity of neutrophils is modulated by lymphocytes and macrophages. The article describes mutual interactions between different factors involved in the reperfusion injury that may enable preparing new treatments, hopefully as effective and successful as reperfusion therapy.

Elevation of serum levels of the anti-inflammatory cytokine interleukin-10 and decreased risk of coronary events in patients with unstable angina

BACKGROUND

Inflammation is an important phenomenon in atherosclerotic plaque growth and in plaque instability. Cytokines are nuclear mediators in the inflammatory response; some have proinflammatory and others anti-inflammatory roles. Proinflammatory cytokines have been associated with worse outcomes in unstable angina. The aims of this study were to determine the role of the anti-inflammatory cytokine interleukin (IL)-10 and the proinflammatory to anti-inflammatory ratios in the short-term prognosis of patients with unstable angina.

METHODS

Serum levels of proinflammatory cytokines IL-1beta, IL-6, and IL-8, and of the anti-inflammatory cytokine IL-10 were determined on admission in 127 consecutive patients with severe unstable angina, and comparisons were made between patients who had cardiovascular events (death, nonfatal myocardial infarction, readmission for refractory angina) (n = 20) and patients without coronary events (n = 107) during a follow-up period of 3 months.

RESULTS

IL-10 levels were lower (0.67 +/- 1.13 vs 1.33 +/- 1.67 pg/mL, P =.04) and IL-8 levels were higher (3.6 +/- 2.41 vs 2.23 +/- 2.47 pg/mL, P =.029) in patients in whom cardiovascular events subsequently developed compared with those without events, with resulting higher proinflammatory to anti-inflammatory cytokine ratios in the former group, whereas no significant differences were seen in IL-1beta or IL-6 levels between the groups, except for the subgroup of patients with prolonged rest angina and persistent electrocardiographic changes. A greater ratio of IL-8 to IL-10 serum levels was observed in patients who had coronary events (28 +/- 25 vs 12 +/- 21, P =.007). The risk of subsequent coronary events increased in patients in the highest quartile of proinflammatory to anti-inflammatory cytokine ratio (IL-8/IL-10). Patients in the highest quartile had a relative risk 3.8 times higher than those in the lowest quartile (P =.01).

CONCLUSIONS

Lower levels of IL-10, with higher proinflammatory to anti-inflammatory cytokine ratios, were observed on admission in patients with unstable angina who subsequently had cardiovascular events. Higher levels of the anti-inflammatory cytokine IL-10 may be needed to provide protection in unstable angina.

Inflammatory response to coronary stent implantation in patients with unstable angina

Previous evidence has shown that coronary angioplasty leads to the release of inflammatory mediators. In this study, we sought to characterize the systemic inflammatory response after coronary stent implantation in patients with unstable angina by measuring different protein markers. Peripheral blood samples were taken before and 24 h, 48 h, and 7 days after successful coronary stenting in 58 patients. Several markers of acute-phase response were determined: C-reactive protein (CRP), alpha2-macroglobulin, haptoglobin, acid alpha1-glycoprotein, prealbumin and albumin. Besides, proinflammatory cytokines (tumor necrosis factor-alpha, IL-6, IL-8) and the anti-inflammatory cytokine IL-10 were also measured. We have found that coronary angioplasty with stent implantation produces a systemic inflammatory response with a rise in inflammation markers concentration. CRP plasma levels declined 1 week after the intervention, but the other marker levels were even higher after 7 days. IL-6 was the only cytokine whose plasma levels significantly increased in peripheral blood after stenting, with a rise after 24 h, maintained after 48 h, and decreased to near-basal levels after 1 week. There was a good correlation between CRP and IL-6 plasma levels (r=0.5, p<0.001). IL-10 levels were slightly decreased after 24 h. Although no significant differences in the means at different time points were found, there was a decrease in IL-10 in most patients 24 h after the intervention. These results indicate that coronary stent implantation induces a systemic inflammatory reaction, with a temporal increase in the concentration of the inflammation markers, especially CRP and IL-6. Since these markers had been previously used as prognostic markers, this needs to be taken into account in patients undergoing stent implantation.

Postprandial lipemia is associated with platelet and monocyte activation and increased monocyte cytokine expression in normolipemic men

The activation of platelets and monocytes has been implicated in the development of cardiovascular diseases. We asked the question if postprandial lipemia following a fat- containing meal is associated with platelet and monocyte activation and increased platelet-monocyte interaction. Thirteen healthy, normal weight, normolipemic males, 20 to 49 years, consumed a 40% fat meal of whole foods. Blood samples were obtained at fasting and 3 1/2 and 6 hours after ingestion. Triglyceride levels increased to 48% over baseline at 3 1/2 hours postconsumption and returned to fasting levels by 6 hours. Multiparameter flow cytometry using monoclonal antibodies showed that the percentage of platelets expressing surface P-selectin and the activated conformation the GPIIb-IIa receptor was significantly higher at 3 1/2 hours compared to fasting. The percentage of platelet-monocyte aggregates increased by 36% at 3 1/2 hours and 43% at 6 hours postconsumption. The percentage of monocytes expressing intracellular tumor necrosis factor-alpha (TNF-alpha) increased seven and eightfold at 3 1/2 and 6 hours, respectively. The expression of interleukin-1beta (IL-1beta increased in a similar manner. These data suggest activation of platelets and monocytes after a moderate fat meal. Repetitive activation of platelets and monocytes could be an early event in the initiation and development of atherosclerosis.

Influence of tumor necrosis factor-alpha gene-308 polymorphism on the development of coronary vasculopathy after cardiac transplantation

BACKGROUND

Tumor necrosis factor-alpha (TNF-alpha) has been implicated in cardiovascular disease. Polymorphism of the TNF-alpha gene promoter region (position -308) influences an individual's production of TNF-alpha. This affects susceptibility to acute rejection after cardiac transplantation. Because the highest serum levels of TNF-alpha have been found in recipients with cardiac transplant vasculopathy and because TNF-alpha blockade can prevent the disease in rabbits, we investigated the effect of TNF-alpha promoter polymorphism on the development of vasculopathy in human cardiac allograft recipients.

METHODS

Using sequence-specific primers to the TNF-alpha gene and polymerase chain reaction, the genotypes of 147 cardiac transplant recipients and 134 heart donors were identified. An association was sought between the presence of high-producing (A homozygotes, GA heterozygotes) or low-producing (G homozygotes) TNF-alpha genotype and the development of coronary vasculopathy, diagnosed by routine surveillance coronary angiography.

RESULTS

We found that 31.9% of recipients and 27.0% of donors were high TNF-alpha producers. The presence of the high-producing TNF-alpha allele led to an earlier diagnosis of vasculopathy; 3.42 years (+/- 91.3 days) vs 3.84 years (+/- 76.3 days) for high- and low-producing cardiac graft recipients, respectively; 3.52 years (+/- 87.3 days) vs 3.78 years (+/- 77.4 days) for high- and low-producing donor grafts, respectively. However, neither of these differences were significant. By Kaplan Meier actuarial analysis and log-rank test, TNF-alpha polymorphism had no effect on the freedom from vasculopathy when considering either recipient (p = 0.99) or donor (p = 0.86) TNF-alpha genotype. Multivariate analysis identified increasing donor age and the number of acute rejection episodes of International Society for Heart and Lung Transplantation grade 3 or greater as independent risk factors for vasculopathy in both the recipient and donor cohorts.

CONCLUSIONS

Polymorphism at position -308 in the promoter region of the TNF-alpha gene fails to predict the development of cardiac transplant-related vasculopathy and cannot be used as a genetic risk marker. This may be because of the effects of immunosuppressive treatment.

Interleukin-10 and tumor necrosis factor gene polymorphisms and risk of coronary artery disease and myocardial infarction

Inflammation plays an important role in the pathogenesis of atherosclerosis and acute coronary syndromes. Cytokines IL-10 and TNF-alpha exert opposite functions in inflammatory reactions, IL-10 acting predominantly as an antiinflammatory and TNF-alpha as a proinflammatory factor. Functional single nucleotide polymorphisms in the genes of IL-10, TNF-alpha, and TNF-beta are associated with gene expression and plasma levels of IL-10 and TNF-alpha. The aim of the study was to assess whether these IL-10 and TNF gene polymorphisms are related to the risk of coronary artery disease (CAD) and myocardial infarction (MI). Consecutive, angiographically examined patients with significant coronary stenoses but without symptoms or signs of old or acute MI constituted the group with CAD (n=998) and patients with old or acute MI constituted the group with MI (n=793). Subjects with neither angiographic CAD nor symptoms or signs of MI (n=340) served as controls. They were matched with the patients for age and sex. Genotyping was performed with techniques based on the polymerase chain reaction. Allele frequencies, genotype distributions, and frequencies of allele combinations for three IL-10 promoter polymorphisms, -1082G/A, -819C/T and -592C/A, were similar between CAD patients, MI patients, and matched controls. Similarly, genetic analysis did not reveal group-specific differences for the TNF-alpha promoter polymorphisms -863C/A and -308G/A, as well as for the TNF-beta intron 1 polymorphism 252G/A. In addition, no relationship was found between specific combinations of IL-10 and TNF alleles, indicative of low IL-10 and high TNF-alpha production, respectively, and CAD or MI. The lack of association persisted also after adjusting for other cardiovascular risk factors. Our findings suggest that six different and functionally relevant polymorphisms of the genes coding for IL-10, TNF-alpha, and TNF-beta are neither separately nor in cooperation associated with the risk of CAD or MI in angiographically examined patients.

Inflammatory pathways in atherosclerosis and acute coronary syndromes

Evidence from a broad range of studies demonstrates that atherosclerosis is a chronic disease that, from its origins to its ultimate complications, involves inflammatory cells (T cells, monocytes, macrophages), inflammatory proteins (cytokines, chemokines), and inflammatory responses from vascular cells (endothelial cell expression of adhesion molecules). Investigators have identified a variety of proteins whose levels might predict cardiovascular risk. Of these candidates, C-reactive protein, tumor necrosis factor-alpha, and interleukin-6 have been most widely studied. There is also the prospect of inflammation as a therapeutic target, with investigators currently debating to what extent the decrease in cardiovascular risk seen with statins, angiotensin-converting enzyme inhibitors, and peroxisome proliferator-activated receptor ligands derives from changes in inflammatory parameters. These advances in basic and clinical science have placed us on a threshold of a new era in cardiovascular medicine.

Polymorphisms in the TNF-alpha and TNF-receptor genes in patients with coronary artery disease

BACKGROUND

Coronary artery disease (CAD) is both multifactorial and polygenic in nature. Atheroma formation, the pathological hallmark of CAD, is an inflammatory process, with pro-inflammatory cytokines, such as tumour necrosis factor-alpha (TNF-alpha), having a major role in its pathogenesis. We have therefore investigated whether polymorphisms in the TNF-alpha (- 238 and - 308), TNF receptor 1 (position - 609 and + 10, intron 6) and TNF receptor 2 (position + 422, codon 198) genes show an association with CAD.

MATERIALS AND METHODS

Patients with angiographically proven single vessel (n = 58) and multivessel (n = 122) CAD were compared to patients with angiographically proven normal coronary arteries (n = 79) and volunteers without clinical evidence of CAD (n = 250). Genotyping was performed by PCR-RFLP analysis. For the TNF-alpha polymorphisms, a meta-analysis of all published studies was also undertaken.

RESULTS

No significant differences in allele or genotype frequencies were found between the normal coronary artery group or healthy volunteers and patients with CAD for any of the polymorphisms. There was also no difference in allele frequency between patients with single- and multivessel disease. For the - 308 and - 238 TNRalpha gene polymorphisms, a meta-analysis of our data and previously published studies failed to demonstrate any significant association with CAD.

CONCLUSIONS

Polymorphisms in the TNF-alpha promoter region and TNF-receptor genes are not associated with the development of CAD.

The role of tumor necrosis factor in cardiac disease

Tumor necrosis factor (TNF) is a proinflammatory cytokine that can produce widespread deleterious effects when expressed in large amounts. It is produced in the heart by both cardiac myocytes and resident macrophages under conditions of cardiac stress, and is thought to be responsible for many of the untoward manifestations of cardiac disease. This article discusses the role of TNF in heart disease and some potential therapeutic modalities that can influence the cytokine activity. The results of controlled studies would suggest that TNF inhibition does not influence the clinical course of patients with heart failure.

Increased concentrations of inflammatory mediators in unstable angina: correlation with serum troponin T

OBJECTIVE

To measure plasma interferon γ, monocyte chemotactic protein-1 (MCP-1), and interleukin 6 and to assess their correlation with cardiac troponin T in unstable angina.

DESIGN

Blood sampling in patients undergoing coronary arteriography for known or suspected ischaemic heart disease.

PATIENTS

76 patients divided in three groups: 29 with unstable angina (group 1), 28 with stable angina (group 2), and 19 without ischaemic heart disease and with angiographically normal coronary arteries (group 3).

MAIN OUTCOME MEASURES

Plasma interleukin 6, interferon γ, MCP-1, and troponin T in the three groups of patients.

RESULTS

Interleukin 6 was increased in group 1 (median 2.19 (range 0.53–50.84) pg/ml) compared with the control group (1.62 (0.79–3.98) pg/ml) (p < 0.005), whereas interferon γ was higher in group 1 (range 0–5.51 pg/ml) than in the other two groups (range 0–0.74 pg/ml and 0–0.37 pg/ml; p < 0.005 and p < 0.001, respectively). Patients with unstable angina (group 1) and positive troponin T had higher concentrations of interferon γ than those with negative troponin T (0–5.51 pg/mlv 0–0.60 pg/ml, p < 0.001). Plasma MCP-1 was also higher in group 1 (median 267 (range 6–8670) pg/ml) than in the other two groups (134 (19–890) pg/ml and 84.5 (5–325) pg/ml; p < 0.005 and p < 0.001, respectively), and among group 1 patients with a positive troponin T assay than in those with normal troponin T (531 (14.5–8670) pg/mlv 69 (6–3333) pg/ml; p < 0.01). There was no difference in plasma interleukin 6 in group 1 patients between those with and without raised troponin T.

CONCLUSIONS

The inflammatory cytokines interferon γ and MCP-1 are increased in patients with unstable angina, particularly in those with raised concentrations of troponin T, suggesting that they are probably related to myocardial cell damage or to plaque rupture and thrombus formation.

Increased concentrations of inflammatory mediators in unstable angina: correlation with serum troponin T

OBJECTIVE

To measure plasma interferon gamma, monocyte chemotactic protein-1 (MCP-1), and interleukin 6 and to assess their correlation with cardiac troponin T in unstable angina.

DESIGN

Blood sampling in patients undergoing coronary arteriography for known or suspected ischaemic heart disease.

PATIENTS

76 patients divided in three groups: 29 with unstable angina (group 1), 28 with stable angina (group 2), and 19 without ischaemic heart disease and with angiographically normal coronary arteries (group 3).

MAIN OUTCOME MEASURES

Plasma interleukin 6, interferon gamma, MCP-1, and troponin T in the three groups of patients.

RESULTS

Interleukin 6 was increased in group 1 (median 2.19 (range 0.53-50.84) pg/ml) compared with the control group (1.62 (0.79-3.98) pg/ml) (p < 0.005), whereas interferon gamma was higher in group 1 (range 0-5.51 pg/ml) than in the other two groups (range 0-0.74 pg/ml and 0-0.37 pg/ml; p < 0.005 and p < 0.001, respectively). Patients with unstable angina (group 1) and positive troponin T had higher concentrations of interferon gamma than those with negative troponin T (0-5.51 pg/ml v 0-0.60 pg/ml, p < 0.001). Plasma MCP-1 was also higher in group 1 (median 267 (range 6-8670) pg/ml) than in the other two groups (134 (19-890) pg/ml and 84.5 (5-325) pg/ml; p < 0.005 and p < 0.001, respectively), and among group 1 patients with a positive troponin T assay than in those with normal troponin T (531 (14.5-8670) pg/ml v 69 (6-3333) pg/ml; p < 0.01). There was no difference in plasma interleukin 6 in group 1 patients between those with and without raised troponin T.

CONCLUSIONS

The inflammatory cytokines interferon gamma and MCP-1 are increased in patients with unstable angina, particularly in those with raised concentrations of troponin T, suggesting that they are probably related to myocardial cell damage or to plaque rupture and thrombus formation.

Activation of the immune system and coronary artery disease: the role of anti-endothelial cell antibodies

On the basis of the role of immuno-mediated inflammation in atherosclerosis we investigated, (1) the prevalence of anti-endothelial cell antibodies (AECA) in ischaemic heart disease (IHD); (2) if beta2-glycoprotein I (beta2-GPI) was the target antigen of AECA; (3) the relationship between AECA, tissue factor (TF) and tissue factor pathway inhibitor (TFPI). In 93 consecutive IHD patients undergoing percutaneous transluminal coronary angioplasty (PTCA) and 105 controls AECA were detected by ELISA on human umbilical vein endothelial cells (HUVEC). AECA positive sera were evaluated for anti-beta2-GPI antibodies by ELISA. TF and TFPI plasma levels were assessed by ELISA. Twelve of 93 (12.9%) IHD patients and only one of 105 controls (0.95%) were AECA positive. The prevalence of AECA was higher in unstable angina (UA) than in effort angina (EA) (P=0.01). Three of 12 AECA positive sera resulted positive for anti-beta2-GPI and showed a marked decrease in EC-binding when tested on HUVEC cultured in serum-free medium. The binding was restored by the addition of beta2-GPI. TF and TFPI levels were similar in AECA positive and AECA negative patients. The rate of angiographically documented clinical recurrences was 66.7% in the AECA positive and 14.8% in the AECA negative group (P=0.0004) with a significant relationship between restenosis and AECA (P<0.0001), unchanged by the inclusion of cardiovascular risk factors in the regression model. Our results suggest a 'role' for AECA in the immune-mediated inflammation in UA beta2-GPI is not the only AECA target antigen. AECA are not responsible for high TF and TFPI levels. The high rate of clinical recurrences after PTCA, confirmed by angiography, in AECA positive patients is in line with such a role and suggests further large-scale 'ad hoc' studies.

The viral anti-inflammatory chemokine-binding protein M-T7 reduces intimal hyperplasia after vascular injury

Chemokines and IFN-gamma function as central regulators of inflammatory responses to vascular injury. Both classes of cytokines are upregulated during restenosis, a response to vascular injury that leads to recurrent atherosclerotic plaque growth, but the relative impact of each class of cytokines remains undetermined. M-T7 is a secreted myxoma viral immunomodulatory glycoprotein that functions both as a species-specific inhibitor of rabbit IFN-gamma and as a chemokine-binding protein, interacting with a wide range of C, C-C, and C-X-C chemokines in a species-nonspecific fashion. We wished to (a) assess the efficacy of purified M-T7 protein in inhibiting intimal hyperplasia after angioplasty injury and (b) exploit unique species-specific functions of M-T7 in order to judge the relative importance of each cytokine class on plaque growth. Anesthetized New Zealand white rabbits and Sprague-Dawley rats received either M-T7 or control at the time of arterial angioplasty injury. Histological analysis at 28 days demonstrated significant reductions in intimal hyperplasia with M-T7 treatment in both models, with an associated early inhibition of inflammatory cell invasion. Purified M-T7 protein inhibits intimal hyperplasia after angioplasty injury in a species-nonspecific fashion, thus implicating the chemokine-binding activity as more critical for prevention of plaque growth after vascular injury.

Increased cardiomyocyte intracellular calcium during endotoxin-induced cardiac dysfunction in guinea pigs

Septic shock is a complex pathophysiologic state characterized by circulatory insufficiency, multiple system organ dysfunction, and frequent mortality. Although profound cardiac dysfunction occurs during sepsis, the pathogenesis of this dysfunction remains poorly understood. To determine whether abnormalities in intramyocyte calcium accumulation might contribute to the development of cardiac dysfunction, we measured myocyte intracellular calcium during peak cardiac dysfunction after an endotoxin challenge. Intraperitoneal administration of Escherichia coli lipopolysaccharide 4 mg/kg to adult guinea pigs resulted in significantly impaired cardiac performance (Langendorff preparation) 18 h after challenge compared with control. This included diminished left ventricular pressure development (56 +/- 7 versus 95 +/- 4 mm Hg, p < 0.05), maximal rate of left ventricular pressure rise (998 +/- 171 versus 1784 +/- 94 mm Hg/s, p < 0.05) and left ventricular pressure fall (1014 +/- 189 versus 1621 +/- 138 mm Hg/s, p < 0.05). Assay of intracellular calcium in fura-2AM-loaded cardiac myocytes demonstrated increased intracellular calcium concentration in myocytes obtained from lipopolysaccharide-challenged animals compared with controls (234 +/- 18 versus 151 +/- 6 nM, p < 0.05). Inhibition of calcium-release channel (ryanodine receptor) opening by administration of dantrolene prevented the increase in intracytoplasmic calcium (159 +/- 8 versus 234 +/- 18 nM, p < 0.05) and partially ameliorated systolic and diastolic ventricular dysfunction. These data indicate that abnormalities of intracellular calcium contribute to the development of endotoxin-induced myocardial dysfunction.

Circulating levels of IL-1beta, a prothrombotic cytokine, are elevated in unstable angina versus stable angina

BACKGROUND

Multiple studies support a role for inflammation in the pathogenesis of coronary atherosclerosis and unstable cardiac syndromes. However, of the known proinflammatory cytokines, only elevated plasma levels of interleukin-6 have been linked to unstable angina. We sought to examine the plasma levels of other major proinflammatory cytokines in similar clinical settings and to determine the extent of the relationship between inflammation and unstable coronary syndromes by measuring the levels of various proinflammatory cytokines in patients with stable and unstable angina.

METHODS

We measured plasma levels of interleukin-1 beta (IL-1beta), tumor necrosis factor alpha (TNF-alpha), and interleukin 6 (IL-6) in 97 patients: 67 with stable angina, 24 with unstable angina, and 15 healthy controls.

RESULTS

Mean levels of IL-1beta were significantly higher in patients with unstable angina as compared to patients with stable angina (p =.009). Levels of IL-6 were significantly higher than control patients for both stable angina and unstable angina patients (p =.031 and.006, respectively). No significant differences were found in the levels of TNF-alpha.

CONCLUSIONS

Our results suggest that both IL-1beta and IL-6 contribute to the pathogenesis of unstable angina, and that the profile of circulating plasma levels of proinflammatory cytokines differs in unstable angina from that in stable angina. Abbreviated Abstract. Multiple studies support a role for inflammation in the pathogenesis of coronary atherosclerosis and unstable cardiac syndromes. We measured plasma levels of interleukin-1 beta (IL-1beta), tumor necrosis factor alpha (TNF-alpha), and interleukin 6 (IL-6) in patients with stable and unstable coronary syndromes. Levels of IL-1beta and IL-6 were found to be elevated in patients with unstable coronary syndromes. No significant differences were found in the levels of TNF-alpha. Our results suggest that both IL-1beta and IL-6 contribute to the pathogenesis of unstable angina.

Endothelial apoptosis: could it have a role in the pathogenesis and treatment of disease?

Endothelial apoptosis can be found in a number of diseases. This review summarizes the current knowledge about the causes and consequences of endothelial apoptosis, and analyzes its possible role in the pathogenesis and treatment of several diseases. Novel forms of therapy based on the proposed pathophysiologic mechanisms are discussed.

Endotoxin and ischemic preconditioning: TNF-alpha concentration and myocardial infarct development in rabbits

Ischemic preconditioning (IP) and prior exposure to lipopolysaccharides (LPS) reduce infarct size (IS) and serum tumor necrosis factor-alpha (TNF-alpha) concentration resulting from myocardial ischemia-reperfusion in rabbits. The decrease in TNF-alpha might relate to an induced TNF-alpha inhibitory serum activity (TNF-alpha-ISA). We analyzed TNF-alpha and TNF-alpha-ISA during 30 and 180 min ischemia and reperfusion, respectively, in anesthetized rabbits either untreated (group 1, n = 7), preconditioned (5 and 10 min ischemia and reperfusion, respectively, group 2, n = 9), or exposed to LPS 72 h before ischemia (group 3, n = 9). TNF-alpha-ISA was assessed by coincubating LPS-stimulated rabbit blood with serum of groups 1-3 and measuring TNF-alpha (WEHI assay). With a comparable area at risk, IS in group 1 was 36.9 +/- 11.1 (SD)%, and it was reduced to 13.1 +/- 11.6% and 17.3 +/- 11.3% (both P < 0.05) in groups 2 and 3, respectively. TNF-alpha was increased during ischemia-reperfusion in group 1 but remained unchanged in rabbits subjected to IP or LPS. TNF-alpha-ISA was detected during ischemia-reperfusion in group 2 (29% and 38% of maximum inhibition, respectively) and during baseline, ischemia and reperfusion in group 3 (51%, 46%, 48% of maximum inhibition, respectively) but was absent in group 1. Cardioprotection by IP and LPS is associated with a reduced TNF-alpha and an induced TNF-alpha-ISA during ischemia-reperfusion.

Plasma levels of interleukin 2, 6, 10 and phenotypic characterization of circulating T lymphocytes in ischemic heart disease

The purpose of this study was to assess lymphocyte receptors expression in patients with ischemic heart diseases, as well as to measure the plasma levels of interleukin (IL) 2, 6 and 10. T Lymphocytes are found in large numbers in human atherosclerotic plaques, indicating that immune and inflammatory mechanisms are important factors in the pathogenesis of atherosclerosis. Recent data have also implicated T lymphocytes in the pathogenetic mechanism of unstable angina and ischemic heart disease. Three groups of patients were studied: 42 with an acute ischemic syndrome (AIS), 36 with stable angina (SA) and 39 healthy controls. To characterize lymphocyte phenotype, flow cytometry was performed in whole-blood samples. IL-2, IL-6 and IL-10 were measured using the ELISA method. Double fluorescence evaluation showed an increase in CD8+/CD11b+ cells (cytotoxic T lymphocytes) and in CD11b+/CD16+CD56+ cells (NK lymphocytes) in the AIS group and in SA group as compared to the control group (P < 0.05 and P < 0.001, respectively). IL-2 was increased in the AIS and SA groups compared to the control group (AIS 4.5 +/- 0.5 pg/ml; SA 6.3 +/- 0.6 pg/ml; controls 2.4 +/- 0.8 pg/ml, P < 0.05), whereas IL-6 was higher in the AIS group than in the other two groups (AIS 10.8 +/- 1.8 pg/ml; SA 1.8 +/- 0.8 pg/ml; controls 1.2 +/- 0.6 pg/ml, P < 0.0001). These data show that patients with ischemic heart disease have an increase in circulating cytotoxic T lymphocytes and in IL-2 plasma levels, irrespective of their clinical presentation, compared to normal control subjects, whereas IL-6 is elevated only in patients with AIS.

Kinetics of tumor necrosis factor alpha in plasma and the cardioprotective effect of a monoclonal antibody to tumor necrosis factor alpha in acute myocardial infarction

BACKGROUND

Inflammation plays a critical role in acute myocardial infarction (AMI) and tumor necrosis factor alpha (TNF-alpha) is a potent inflammatory trigger. This study was designed to examine the kinetics of TNF-alpha in plasma in patients with AMI and the potential benefit of inhibition of TNF-alpha monoclonal antibody in AMI.

METHODS AND RESULTS

TNF-alpha levels in plasma were measured in 42 patients with AMI. TNF-alpha levels were elevated at 4 hours after onset of chest pain and declined to control values at 48 hours. TNF-alpha levels were higher in patients with Killip III and IV than in those with Killip I and II (P <.01). To examine the pathogenic role of TNF-alpha, New Zealand White rabbits were treated with buffer or a TNF-alpha monoclonal antibody before left anterior descending artery (LAD) ligation. Treatment with the TNF-alpha monoclonal antibody decreased area of necrosis, number of circulating endothelial cells, and lipid peroxidation product malonaldehyde bis(dimethyl acetal). There was a significant correlation of TNF-alpha levels with peak CK-MB in AMI patients, and area of necrosis, MDA, and circulating endothelial cells in rabbits (all P <.05).

CONCLUSIONS

TNF-alpha release early in the course of AMI contributes to myocardial injury and dysfunction. Treatment with the monoclonal antibody against TNF-alpha can be cardioprotective, particularly in the setting of heart failure in patients with AMI.

Inflammation, the acute phase response and atherosclerosis

There is increasing evidence that atherosclerosis is a chronic inflammatory disorder resulting from a combination of processes, and that acute exacerbations of this inflammation are associated with the acute coronary syndromes such as myocardial infarction and unstable angina. Measurement of the serum level of acute phase proteins, such as C-reactive protein and serum amyloid A protein, has been used to predict the risk of acute events in patients with atherosclerosis. Prospective studies have shown that higher serum acute phase protein levels, often within the reference range, are associated with increased risk of myocardial infarction (MI), stroke or peripheral vascular disease and predict risk of infarction and death among high-risk patients. These observations have important implications for the assessment of patients and for treatment.

Tyrosine kinase-dependent modulation by interferon-alpha of the ATP-sensitive K+ current in rabbit ventricular myocytes

We examined the effects of interferon-alpha on the ATP-sensitive K+ current (IK,ATP) in rabbit ventricular cells using the patch-clamp technique. IK,ATP was induced by NaCN. Whole-cell experiments indicated that interferon-alpha (5 x 10(2) - 2.4 x 10(4) U/ml) inhibited IK,ATP in a concentration-dependent manner (60.7+/-7.5% with 2.4 x 10(4) U/ml). In cell-attached configuration, interferon-alpha (2.4 x 10(4) U/ml) applied to the external solution also inhibited the activity of the single ATP-sensitive K+ (KATP) channel by 56.0+/-5.8% without affecting the single channel conductance. The inhibitory effect of IK,ATP by interferon-alpha was blocked by genistein and herbimycin A, tyrosine kinase inhibitors, but was not affected by N-(2-metylpiperazyl)-5-isoquinolinesulfoamide (H-7), an inhibitor of protein kinase C and cAMP-dependent protein kinase. These findings suggest that interferon-alpha inhibits the cardiac KATP channel through the activation of tyrosine kinase. The tyrosine kinase-mediated inhibition of IK,ATP by cytokines may aggravate cell damage during myocardial ischemia.

The role of linoleic acid in endothelial cell gene expression. Relationship to atherosclerosis

There is evidence that linoleic acid plays a critical role in gene expression and vascular function as it relates to the pathogenesis of atherosclerosis. The lipid environment, particularly linoleic acid and its derivatives, of the vascular endothelium may profoundly influence the inflammatory response mediated by cytokines. Modulations in the level of activity of a select set of endothelial transcription factors appear to provide a mechanism for linking lipid/cytokine-mediated vessel wall dysfunction, including endothelial cell activation, altered proteoglycan metabolism, and endothelial barrier dysfunction, with the onset of atherosclerotic lesion formation. The activity of endothelial transcription factors is in part regulated by the balance of cellular oxidative stress and antioxidant status. Our data suggest that linoleic acid can activate the vascular endothelium and may thus be an atherogenic fatty acid. Furthermore, nutrients/chemicals with antioxidant properties can protect endothelial cells against lipid-mediated cell injury, suggesting that oxidative stress is a critical component in linoleic acid-mediated gene expression. Our discoveries that linoleic acid can influence significantly the cytokine-mediated inflammatory response may open new fields in dietary intervention of atherosclerosis.

Effects of tumour necrosis factor-alpha on left ventricular function in the rat isolated perfused heart: possible mechanisms for a decline in cardiac function

1. The cardiac depressant actions of TNF were investigated in the isolated perfused rat heart under constant flow (10 ml min(-1)) and constant pressure (70 mmHg) conditions, using a recirculating (50 ml) mode of perfusion. 2. Under constant flow conditions TNF (20 ng ml(-1)) caused an early (< 25 min) decrease in left ventricular developed pressure (LVDP), which was maintained for 90 min (LVDP after 90 min: control vs TNF; 110 +/- 4 vs 82 +/- 10 mmHg, P < 0.01). 3. The depression in cardiac function seen with TNF under constant flow conditions, was blocked by the ceramidase inhibitor N-oleoylethanolamine (NOE), 1 microM, (LVDP after 90 min: TNF vs TNF with NOE; 82 +/- 10 vs 11 +/- 5 mmHg, P < 0.05). 4. In hearts perfused at constant pressure, TNF caused a decrease in coronary flow rate (change in flow 20 min after TNF: control vs TNF; -3.0 +/- 0.9 vs -8.7 +/- 1.2 ml min(-1), P < 0.01). This was paralleled by a negative inotropic effect (change in LVDP 20 min after TNF: control vs TNF; -17 +/- 7 vs -46 +/- 6 mmHg, P < 0.01). The decline in function was more rapid and more severe than that seen under conditions of constant flow. 5. These data indicate that cardiac function can be disrupted by TNF on two levels, firstly via a direct, ceramidase dependant negative inotropic effect, and secondly via an indirect coronary vasoconstriction.

Evidence of phenotypic alteration as a cause of systolic dysfunction in the failing heart

This article describes the phenotype of dilated cardiomyopathy in humans and describes parallel studies in experimental models that support or refute the relevance of these changes to the development of the heart failure phenotype.

Increased levels of soluble tumor necrosis factor receptors in atherosclerosis: no clear relationship with levels of tumor necrosis factor

Inflammatory mediators, such as tumor necrosis factor alpha (TNF), may be important in the pathogenesis of atherosclerosis. Interactions between TNF and its target cell(s) requires the presence of specific receptors on the latter. Plasma levels of the two soluble forms of these receptors (tumor necrosis factor receptors, (sTNFr)) and TNF itself were measured by ELISA in 20 patients with peripheral vascular disease (PVD), 20 survivors of a myocardial infarction, and 20 age and sex matched controls. Levels of the p55 variant of the sTNFr were unchanged but levels of the p75 variant were increased in both groups of patients (ANOVA both P < 0.01). TNF was also raised in both groups of patients (both P < 0.05) but levels did not correlate with either sTNFr. In atherosclerosis, increased levels of p75 sTNFr may be further evidence of inappropriate leukocyte activation but unlikely to modulate the effect of free plasma TNF.

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.

Polymorphisms of the tumour necrosis factor-alpha gene, coronary heart disease and obesity

BACKGROUND

Tumour necrosis factor-alpha (TNF-alpha) is a cytokine that has multiple functions. Through its effects on lipid metabolism, coagulation, insulin resistance and endothelial function, TNF-alpha could be involved in cardiovascular pathophysiology. Given this possibility, we hypothesized that polymorphisms of the TNF-alpha gene might be associated with a predisposition to coronary heart disease (CHD).

METHODS

The entire coding region and 1053 bp upstream of the transcription start site of the TNF-alpha gene were screened for polymorphisms using polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and sequencing. Five polymorphisms were identified: four were located in the upstream region at positions -857, -851, -308, -238 from the first transcribed nucleotide and one was found in a non-translated region at position +691. Six-hundred and forty-one patients with myocardial infarction (MI) and 710 control subjects from the ECTIM Study were genotyped.

RESULTS

The genotype frequencies were similar in cases and control subjects in the high-risk population of Belfast and in France; however, the TNF-alpha/-308A allele was more frequent in Belfast than in France (0.242 vs. 0.157; P < 0.0001), and carriers of this allele were more frequently obese than non-carriers [1.52 (1.15-1.99), P < 0.004]. No associations were found for the other polymorphisms.

CONCLUSIONS

These results suggest that polymorphisms of the TNF-alpha gene are unlikely to contribute to CHD risk in an important way, but the TNF-alpha/-308 polymorphism should be investigated further in relation to obesity.

Systemic inflammatory responses in acute coronary syndrome: increased activity observed in polymorphonuclear leukocytes but not T lymphocytes

BACKGROUND

Local inflammation within the coronary arteries is involved in the pathogenesis of acute coronary syndrome. However, the contribution of a systemic inflammatory response to the pathogenesis of this syndrome has not been well characterized. Accordingly, we investigated systemic inflammatory responses in patients with acute coronary syndrome.

METHODS

A total of 83 patients with ischemic heart disease (15 with stable exertional angina and 68 with acute coronary syndrome) were studied. The luminol-dependent chemiluminescence (CL) response of polymorphonuclear leukocytes (PMNs), which reflects their ability to generate oxygen species, was used as a marker for PMN activation. Soluble interleukin-2 receptor (sIL-2R) levels were measured to assess T-lymphocyte activation.

RESULTS

CL counts of whole blood from patients with acute coronary syndrome were twice those of patients with stable angina (2.38 +/- 0.22 vs 1.10 +/- 0.17 x 10(6) counts, P < 0.05). A comparison of CL counts between patients with unstable angina and those with acute myocardial infarction revealed no significant differences. T-lymphocyte activity, measured by serum sIL-2R, was significantly lower in patients with acute coronary syndrome than those with stable angina (214.3 +/- 11.5 vs. 358.3 +/- 115.7 U/ml, P < 0.05).

CONCLUSIONS

This investigation shows that there is a systemic increase in PMN activity and a decrease in T-lymphocyte activity in patients with acute coronary syndrome. This contrasts with the pattern of cellular activation seen at sites of local inflammation within atherosclerotic plaques, suggesting that two independent inflammatory processes (local and systemic) may be involved in the pathogenesis of this syndrome.

Cytokine inhibitors in patients with heart failure and impaired functional capacity

Cytokines are proteins with pleiotropic biological effects, but the pathophysiologic role of cytokine inhibitors in advanced cardiac disease remains unclear. We assessed the levels of tumor necrosis factor (TNF)-alpha and its soluble receptors I (sTNF-RI) and II (sTNF-RII), soluble interleukin-1 receptor antagonist (sIL-1 Ra), and interleukin-6 soluble receptor (IL-6 sR) in sera from 11 patients with severe chronic congestive heart failure (mean left ventricular ejection fraction 19 +/- 6%; mean symptom-limited oxygen consumption 13 +/- 4 ml/min per kg) and 11 healthy volunteers. The serum concentrations of TNF, sTNF-RI, and sIL-1 Ra, but not of sTNF-RII and IL-6 sR, were significantly increased in heart failure patients. Importantly, their symptom-limited oxygen consumption was strongly associated with both sTNF-RI (R = -0.68, p = 0.04) and sIL-1 Ra (R = -0.77, p = 0.01). These results suggest that cytokine inhibitors from different receptor families may be involved in functional disability, a characteristic feature in patients with severe congestive heart failure. Understanding the response of cytokine inhibitors to heart failure might have therapeutic value as interventions against cytokines become available.

Leukocyte activation in atherosclerosis: correlation with risk factors

Leukocytes have been implicated in the development of atherosclerotic vascular diseases, and numerous abnormalities of leukocytes in conjunction with atherosclerosis have been reported. The aim of this study of middle-aged asymptomatic subjects with early atherosclerosis was to determine whether a relationship exists between the levels of plasma markers of leukocyte activation, i.e. cytokines and proteases and risk factors for atherosclerosis or the degree of atherosclerotic disease. Using ELISAs we measured the plasma levels of neutrophil gelatinase-associated lipocalin (NGAL), neutrophil protease 4 (NP4) as markers for neutrophil activation, tumor necrosis factor alpha (TNF) and soluble TNF receptor-1 (sTNFR-1) as markers of monocyte/macrophage activation in 156 subjects with asymptomatic carotid artery plaque detected at ultrasound examination. Plasma TNF and sTNFR-1 levels were found to correlate with systolic blood pressure (r = 0.32, P < 0.04 and r = 0.22, P < 0.05, respectively). plasma NGAL level to correlate with diastolic blood pressure (r = 0.22; P < 0.005), the plasma levels of sTNFR-1 and NGAL to correlate with age (r = 0.28, P < 0.001 and r = 0.20, P < 0.05, respectively). As compared with non-smokers (n = 112), smokers (n = 43) had higher plasma levels of TNF (2.9 vs. 1.4 microg/l; P < 0.02) and of NP4 (27.5 vs. 23.4 microg/l; P < 0.05). The plasma NGAL level was higher in hypertensive women (n = 7) than in normotensive women (n = 85) (109 vs. 87 microg/l; P < 0.05). We thus demonstrated that, in subjects with asymptomatic early atherosclerosis, the plasma levels of markers of systemic leukocyte activation were correlated with age and blood pressure, and were higher in smokers and hypertensives. These results support the hypothesized relationship between the level of systemic leukocyte activation and risk factors for atherosclerotic vascular disease.

Circulating levels of cytokines and their endogenous modulators in patients with mild to severe congestive heart failure due to coronary artery disease or hypertension

OBJECTIVES

This study sought to determine the circulating levels of cytokines and their respective endogenous modulators in patients with congestive heart failure of variable severity.

BACKGROUND

Activation of immune elements localized in the heart or periphery, or both, may promote release of cytokines in patients with congestive heart failure. Although an increased circulating level of tumor necrosis factor-alpha (TNF-alpha) and its soluble receptor type II (sTNF-RII) is well documented, less is known about other cytokines (i.e., interleukin-1-beta [IL-1-beta], interleukin-6 [IL-6] and interleukin-2 [IL-2] and their soluble receptor/receptor antagonists).

METHODS

Circulating levels of TNF-alpha and sTNF-RII, IL-1-beta, IL-1 receptor antagonist (IL-1-Ra), IL-6, IL-6 soluble receptor (IL-6-sR), IL-2 and IL-2 soluble receptor-alpha were measured using enzyme-linked immunosorbent assay kits (Quantikine, R&D Systems) in 80 patients with congestive heart failure due to coronary artery disease or hypertension. The severity of their symptoms, which ranged from New York Heart Association functional class I to IV, was confirmed by measurement of peak oxygen consumption.

RESULTS

The percentage of patients with elevated levels of cytokines and their corresponding soluble receptor/receptor antagonists significantly increased with functional class. For TNF-alpha and IL-1-beta, the percentage of patients with elevated levels of soluble receptor/receptor antagonists was higher than that of patients with elevated levels of the cytokine itself. For IL-6, the percentage of patients with elevated levels of IL-6-sR tended to be lower than that of patients with elevated levels of IL-6. All but two patients had undetectable levels of IL-2, and all but seven had levels of IL-2-sR within a normal range.

CONCLUSIONS

In patients with congestive heart failure, circulating levels of cytokines increased with the severity of symptoms. In these patients, circulating levels of sTNF-RII and IL-1-Ra are more sensitive markers of immune activation than are circulating levels of TNF-alpha and IL-1-beta, respectively. Levels of IL-2 and IL-2-sR are not elevated when congestive heart failure is due to coronary artery disease or hypertension.

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.

Ischemic colitis during interferon-alpha treatment for chronic active hepatitis C

Between 1991 and 1994, at Hoshigaoka Koseinenkin Hospital, we treated 280 patients with chronic hepatitis C with interferon (IFN), and ischemic colitis occurred in two patients (0.7%) during the treatment. Melena appeared in case 1 in the 2nd month after the initiation of IFN-alpha treatment, and in case 2 in the 6th month. In both patients, longitudinal ulcerations in the descending colon were revealed by urgent colonoscopy, and these resolved within 2 weeks after discontinuation of the IFN treatment. It appears that ischemic colitis was associated with the IFN treatment, suggesting that attention should be paid to this possible complication.

Cytoprotective mechanisms in cultured cardiomyocytes

Tumor necrosis factor-alpha (TNF-alpha), a potent cytokine mainly secreted by macrophages exerts pleiotropic effects on different cell types. However, the intracellular mediators of its action are not yet well characterized. To get an insight into endogenous cytoprotective mechanisms, we developed an in vitro model based on cultured cardiomyocytes treated with TNF-alpha at which we examined gene expression of heat shock proteins (HSP-27, HSP-70 and ubiquitin). Cardiomyocytes were isolated from the hearts of 18 day old fetal mice by enzymatic dissociation and grown in minimum essential medium containing 10% fetal calf serum. Spontaneously contractile cells were serum deprived for 24 h and treated with TNF-alpha (25 ng/ml) for 1, 2, 4, 6, 8, 12, and 24 h After each incubation, cells were processed to extract total proteins for Western and total RNA for Northern blot analyses. TNF-alpha induced arrhythmias and cessation of spontaneous contractions in a concentration and time dependent manner. Steady state (ubiquitin) or undetectable mRNA levels (HSP-27, HSP-70) were drastically induced (> 4 fold for all three genes vs untreated control cells) by TNF-alpha, reaching maximal values between 6-8 h of stimulation. Thereafter, the expression of these stress genes declined but remained elevated as compared to control. By Western blot analysis, we found increased multiple bands of ubiquitin protein conjugates in TNF-alpha treated cells whereas no significant change in HSP-27 protein accumulation until 12 h was observed as compared to control. 24 h of TNF-alpha incubation resulted in partial cellular necrosis. Our results indicate that TNF-alpha induces in cardiomyocytes transiently gene expression for cytoprotective molecules like HSP-27, HSP-70 and ubiquitin, suggesting these stress proteins to participate in subsequent defense mechanisms, for example in postischemic myocardial recovery.

Enhanced NO production during Mg deficiency and its role in mediating red blood cell glutathione loss

The effect of dietary Mg deficiency on nitric oxide (NO) production and its role in mediating oxidative depletion of red blood cell (RBC) glutathione in rats were investigated. Male Sprague-Dawley rats were placed on Mg-deficient or Mg-sufficient diets for up to 3 wk. Plasma nitrate plus nitrite levels, determined by the Escherichia coli reductase/Griess reagent procedures, increased 1.7-fold during the 1st wk and increased 2- to 2.4-fold during the 2nd and 3rd wk on the Mg-deficient diet. In association, substantial losses (approximately 50%) of RBC glutathione occurred during the 2nd and 3rd wk. Administration of the NO synthesis inhibitor NG-nitro-L-arginine methyl ester (L-NAME) in drinking water (0.5 mg/ml) effectively blunted the increases in plasma nitrate/nitrite during Mg deficiency. Concomitantly, losses of RBC glutathione exhibited by Mg-deficient rats were significantly attenuated. Packed RBCs, obtained from Mg-deficient but not from Mg-sufficient animals, displayed a prominent nitrosyl hemoglobin signal detected by electron spin resonance spectroscopy; the signals of the samples from the L-NAME-treated Mg-deficient rats were greatly reduced. With isolated RBCs, losses of the glutathione could be induced directly by peroxynitrite or 3-morpholinosydnonimine, which generates NO + .O2-, but not by NO (from sodium nitroprusside) alone, in a concentration-dependent manner. The results clearly indicate that NO overproduction occurs and participates in RBC glutathione loss during Mg deficiency. Because neutrophil activation also occurs, we suggest that NO might interact with superoxide anions to form peroxynitrite, which then directly oxidizes RBC glutathione.

Further evidence of the presence of constitutive and inducible nitric oxide synthase isoforms in human platelets

Previous studies have suggested the presence of nitric oxide synthase (NOS) enzyme in human platelets. We herein provide definitive evidence for the presence of both endothelial constitutive NOS (ecNOS) and inducible NOS (iNOS) isoforms and their mRNA in human platelets. Total RNA was isolated from human platelets, and reverse-transcription polymerase chain reaction (RT-PCR) demonstrated the expression of the ecNOS and iNOS isoforms in platelets. High-stringency Southern analysis confirmed the molecular authenticity of the RT-PCR products for each NOS isoform. Western analysis with mouse monoclonal antibody against human ecNOS consistently demonstrated a band with a molecular weight of 140-150 kDa. Western analysis with mouse monoclonal antibody against rat macrophage iNOS showed a single 200-kDa band in both resting and lipopolysaccharide (LPS)-plus interferon-gamma (IFN-gamma)-stimulated platelets. Immunoprecipitation further confirmed the presence of the 200-kDa iNOS band. Expression of iNOS protein, measured with densitometry, was increased in LPS- and IFN-gamma-stimulated platelets (p < 0.01 vs. resting platelets). Thus, human platelets possess both ecNOS and iNOS isoforms and their mRNA, and iNOS exhibits molecular weight and kinetic characteristics distinct from those of ecNOS.

The immune system mediates blood-brain barrier damage; possible implications for pathophysiology of neuropsychiatric illnesses

In this investigation the effects of immune activation on the brain are characterized. In order to study this, we used a model for chronic immune activation, the myocardial infarction, and intravenous injections with the pro-inflammatory cytokine Tumour Necrosis Factor alpha (TNF-α). The incentive for this study is the observation that myocardial infarction is accompanied by behavioural and neuronal abnormalities. The effects of myocardial infarction on the brain and its functioning are widespread. In order to examine the mechanism through which this interaction occurs, a group of rats underwent an experimentally induced myocardial infarction whereafter immunohistochemistry was performed on slices of the brain. This experiment revealed regional serum protein extravasation, pointing to leakage of the blood-brain barrier. This process occurred in certain cortical, subcortical and hindbrain areas in discrete patches. The leakage was co-localized with the expression of the immune activation marker ICAM-1. A second group of rats was therefore injected with TNF-α, a major pro-inflammatory cytokine, to assess the involvement of the immune system in the effects shown. This procedure rendered the same results. It is concluded that myocardial infarction may interfere with the integrity of the blood-brain barrier and possibly with brain functioning through activation of the immune system. The relevance for pathophysiological processes is discussed.

Clinical and angiographic correlates of leukocyte activation in unstable angina

OBJECTIVES

This study sought to evaluate the relation, if any, between clinical and angiographic findings in patients with unstable angina and monocyte and neutrophil CD11b/CD18 receptor density. The expression of HLA-DR molecules on T lymphocytes, an index of activation of these cells, was also investigated.

BACKGROUND

Although activation of neutrophils and monocytes has recently been shown in unstable angina, no studies have correlated activation indexes with clinical and angiographic features of patients with this clinical condition.

METHODS

Sixty patients underwent diagnostic coronary arteriography and simultaneous blood sampling from the aorta and coronary sinus before injection of contrast medium. Cell surface receptors were detected by direct immunofluorescence evaluated by flow cytometry using monoclonal antibodies tagged with fluorescent markers.

RESULTS

In 38 patients with unstable angina, neutrophils and monocytes showed a significantly higher expression of CD11b/CD18 adhesion receptors in coronary sinus than aortic blood (p < 0.0001 and p < 0.001, respectively). When these patients were analyzed according to clinical characteristics or angiographic findings, no difference in CD11b/CD18 receptor expression in coronary sinus blood was found between the various subgroups, except for patients with at least one episode of chest pain at rest within 48 h of coronary arteriography and a higher neutrophil adhesion molecule density than patients who remained asymptomatic (p = 0.04). Lymphocytes in patients with stable and unstable angina showed a similar percent expression of CD2/CD19 and CD3/HLA-DR antigens, with no difference between aortic and coronary sinus blood.

CONCLUSION

These results in a larger cohort confirm previous data that neutrophil and monocyte CD11b/CD18 adhesion molecules show a higher expression in the coronary sinus blood of patients with unstable angina. Among clinical and angiographic findings in patients with unstable angina, only the occurrence of chest pain within 48 h of coronary angiography was related to significantly higher values of neutrophil fluorescence intensity, suggesting that the degree of neutrophil activation is related to the proximity of rest angina episodes to blood sampling. Finally, our data do not support the concept of systemic or transcardiac lymphocyte activation in unstable angina.

Role of glutathione redox cycle in TNF-alpha-mediated endothelial cell dysfunction

Modulation of the glutathione redox cycle may influence tumor necrosis factor-alpha (TNF)-mediated disturbances of endothelial integrity. To test this hypothesis, normal endothelial cells or cells with either increased or decreased glutathione levels were exposed to 100 ng (500 U) TNF/ml. Increased glutathione levels were achieved by exposure to 0.2 mM N-acetyl-L-cysteine (NAC) and decreased glutathione levels by exposure to 25 microM buthionine sulfoximine (BSO). Several components of the glutathione redox cycle as well as markers of endothelial integrity, such as cytoplasmic free calcium and transendothelial albumin transfer, were measured in the treated cells. Exposure to TNF for 3 and 6 h decreased total glutathione levels, which was followed by an increase at later time points. Moreover, treatment with TNF resulted in an increase in the ratio of oxidized to reduced glutathione, intracellular free calcium, albumin transfer across endothelial monolayers and lipid hydroperoxides. However, an increase in lipid hydroperoxides was seen only when endothelial cell cultures were supplemented with iron. BSO treatment increased susceptibility of endothelial cells to TNF-mediated metabolic disturbances. On the other hand, NAC partially protected against TNF-induced injury to endothelial monolayers. Our results demonstrate the important role of the glutathione redox cycle in TNF-mediated disturbances of the vascular endothelium and indicate that modulation of glutathione levels may potentiate the injurious effects of this inflammatory cytokine.

Monocyte-related cytokines in acute myocardial infarction

To elucidate the role of monocytes in the cytokine system in acute myocardial infarction (AMI), we examined the time courses of plasma concentrations and generation capacities of monocyte-related cytokines in 17 consecutive patients with uncomplicated AMI (from day 1 to 28) and in 10 control subjects. The concentrations of monocyte-related cytokines were measured by enzyme immunoassay with horseradish peroxidase. Cytokine generation capacity was evaluated by cytokine concentrations in the culture solution 24 hours after incubation of 0.5 ml whole blood with 5 micrograms lipopolysaccharide. Two distinct patterns of increases in the cytokine concentrations were noted: transient (plasma interleukin [IL]-6) and sustained (plasma macrophage colony-stimulating factor and generation capacities of IL-1 alpha, IL-6, granulocyte colony-stimulating factor, and tumor necrosis factor alpha). There was no significant increase in the concentrations of other cytokines. These results indicate that the concentrations of the monocyte-related cytokines dynamically change during the course of AMI, suggesting that they may contribute to the inflammatory and subsequent proliferative responses in AMI.