Tumor necrosis factor-alpha contributes to ischemia- and reperfusion-induced endothelial activation in isolated hearts

Metabolic Inflammation-A Role for Hepatic Inflammatory Pathways as Drivers of Comorbidities in Nonalcoholic Fatty Liver Disease?

Nonalcoholic fatty liver disease (NAFLD) is a global and growing health concern. Emerging evidence points toward metabolic inflammation as a key process in the fatty liver that contributes to multiorgan morbidity. Key extrahepatic comorbidities that are influenced by NAFLD are type 2 diabetes, cardiovascular disease, and impaired neurocognitive function. Importantly, the presence of nonalcoholic steatohepatitis and advanced hepatic fibrosis increase the risk for systemic comorbidity in NAFLD. Although the precise nature of the crosstalk between the liver and other organs has not yet been fully elucidated, there is emerging evidence that metabolic inflammation-in part, emanating from the fatty liver-is the engine that drives cellular dysfunction, cell death, and deleterious remodeling within various body tissues. This review describes several inflammatory pathways and mediators that have been implicated as links between NAFLD and type 2 diabetes, cardiovascular disease, and neurocognitive decline.

Reperfusion injury as a target for diminishing infarct size

Therapies for preventing reperfusion injury (RI) have been widely studied. However, the attempts to transfer cardioprotective therapies for reducing RI from experiments into clinical practice have been so far unsuccessful. Pathophysiological mechanisms of RI are complicated and compose of many pathways e.g. hypercontracture-mediated sarcolemma rupture, mitochondrial permeability transition pore persistent opening, reactive oxygen species formation, inflammation and no-reflow phenomenon. Based on research, it cannot be determined which mechanism dominates, probably they cooperate with a domination of one or another in different clinical circumstances. Our hypothesis is, that only intervention that at the same time interferes with different (all?) pathways of RI may turn out to be effective in decreasing the final area of infarction.

Myocardial Ischemia and Diabetes Mellitus: Role of Oxidative Stress in the Connection between Cardiac Metabolism and Coronary Blood Flow

Ischemic heart disease (IHD) has several risk factors, among which diabetes mellitus represents one of the most important. In diabetic patients, the pathophysiology of myocardial ischemia remains unclear yet: some have atherosclerotic plaque which obstructs coronary blood flow, others show myocardial ischemia due to coronary microvascular dysfunction in the absence of plaques in epicardial vessels. In the cross-talk between myocardial metabolism and coronary blood flow (CBF), ion channels have a main role, and, in diabetic patients, they are involved in the pathophysiology of IHD. The exposition to the different cardiovascular risk factors and the ischemic condition determine an imbalance of the redox state, defined as oxidative stress, which shows itself with oxidant accumulation and antioxidant deficiency. In particular, several products of myocardial metabolism, belonging to oxidative stress, may influence ion channel function, altering their capacity to modulate CBF, in response to myocardial metabolism, and predisposing to myocardial ischemia. For this reason, considering the role of oxidative and ion channels in the pathophysiology of myocardial ischemia, it is allowed to consider new therapeutic perspectives in the treatment of IHD.

Nicorandil modulated macrophages activation and polarization via NF-κb signaling pathway

Nicorandil, a drug with both nitrate-like and ATP-sensitive potassium (K_ATP) channel-activating properties, has been well demonstrated in various aspects of myocardial infarction (MI), especially in inhibiting cell apoptosis and increasing coronary flow. However, the role of nicorandil in regulating inflammation and angiogenesis following myocardial infarction is still unrevealed. In the present study, we explored the effect of nicorandil on macrophage phenotype transition and inflammation regulation and the potential underlying mechanisms. For the phenotype transition and phagocytosis ability of macrophages detection, flow cytometry analysis was used. The inflammation factors were measured with ELISA and qRT-PCR. Western blot was used to assess the levels of NF-κb and its target genes and VEGF expression. The tube formation ability of endothelial cells was examined on matrigel. We discovered that nicorandil can obviously inhibit the differentiation of monocytes into mature macrophages and decrease M1 phenotype transition both in peritoneal macrophages and cultured macrophage cell line in normal or hypoxia and serum deprivation (H/SD) conditions. Meanwhile, nicorandil can induce an anti-inflammatory M2 phenotype. Thereby, nicorandil regulated macrophages switching to M1/M2 status. Our data further showed that NF-κb and the expression of its target genes were pivotal players in the regulation of macrophages phenotype. Besides, we also showed that nicorandil can promote the tube formation and VEGF expression in endothelial cells. We concluded that nicorandil may serve as an effective modulator of NF-κb signaling pathway during the pathogenesis of MI via regulating M1/M2 status and promoting angiogenesis.

Protective Effects of HDL Against Ischemia/Reperfusion Injury

Several lines of evidence suggest that, besides being a strong independent predictor of the occurrence of primary coronary events, a low plasma high density lipoprotein (HDL) cholesterol level is also associated with short- and long-term unfavorable prognosis in patients, who have recovered from a myocardial infarction, suggesting a direct detrimental effect of low HDL on post-ischemic myocardial function. Experiments performed in ex vivo and in vivo models of myocardial ischemia/reperfusion (I/R) injury have clearly shown that HDL are able to preserve cardiac function when given before ischemia or at reperfusion; the protective effects of HDL against I/R injury have been also confirmed in other tissues and organs, as brain and hind limb. HDL were shown to act on coronary endothelial cells, by limiting the increase of endothelium permeability and promoting vasodilation and neoangiogenesis, on white blood cells, by reducing their infiltration into the ischemic tissue and the release of pro-inflammatory and matrix-degrading molecules, and on cardiomyocytes, by preventing the activation of the apoptotic cascade. Synthetic HDL retains the cardioprotective activity of plasma-derived HDL and may become a useful adjunctive therapy to improve clinical outcomes in patients with acute coronary syndromes or undergoing coronary procedures.

Pathophysiology of Myocardial Infarction

Myocardial infarction is defined as sudden ischemic death of myocardial tissue. In the clinical context, myocardial infarction is usually due to thrombotic occlusion of a coronary vessel caused by rupture of a vulnerable plaque. Ischemia induces profound metabolic and ionic perturbations in the affected myocardium and causes rapid depression of systolic function. Prolonged myocardial ischemia activates a "wavefront" of cardiomyocyte death that extends from the subendocardium to the subepicardium. Mitochondrial alterations are prominently involved in apoptosis and necrosis of cardiomyocytes in the infarcted heart. The adult mammalian heart has negligible regenerative capacity, thus the infarcted myocardium heals through formation of a scar. Infarct healing is dependent on an inflammatory cascade, triggered by alarmins released by dying cells. Clearance of dead cells and matrix debris by infiltrating phagocytes activates anti-inflammatory pathways leading to suppression of cytokine and chemokine signaling. Activation of the renin-angiotensin-aldosterone system and release of transforming growth factor-β induce conversion of fibroblasts into myofibroblasts, promoting deposition of extracellular matrix proteins. Infarct healing is intertwined with geometric remodeling of the chamber, characterized by dilation, hypertrophy of viable segments, and progressive dysfunction. This review manuscript describes the molecular signals and cellular effectors implicated in injury, repair, and remodeling of the infarcted heart, the mechanistic basis of the most common complications associated with myocardial infarction, and the pathophysiologic effects of established treatment strategies. Moreover, we discuss the implications of pathophysiological insights in design and implementation of new promising therapeutic approaches for patients with myocardial infarction.

Effect of hydrogen sulfide on inflammatory cytokines in acute myocardial ischemia injury in rats

Hydrogen sulfide (H₂S) is believed to be involved in numerous physiological and pathophysiological processes, and now it is recognized as the third endogenous signaling gasotransmitter, following nitric oxide and carbon monoxide; however, the effects of H₂S on inflammatory factors in acute myocardial ischemia injury in rats have not been clarified. In the present study, sodium hydrosulfide (NaHS) was used as the H₂S donor. Thirty-six male Sprague Dawley rats were randomly divided into five groups: Sham, ischemia, ischemia + low-dose (0.78 mg/kg) NaHS, ischemia + medium-dose (1.56 mg/kg) NaHS, ischemia + high-dose (3.12 mg/kg) NaHS and ischemia + propargylglycine (PPG) (30 mg/kg). The rats in each group were sacrificed 6 h after the surgery for sample collection. Compared with the ischemia group, the cardiac damage in the rats in the ischemia + NaHS groups was significantly reduced, particularly in the high-dose group; in the ischemia + PPG group, the myocardial injury was aggravated compared with that in the ischemia group. Compared with the ischemia group, the levels of interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α) in the serum of rats in the ischemia + medium- and high-dose NaHS groups were significantly reduced, and the expression of intercellular adhesion molecule-1 (ICAM-1) mRNA and nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) protein in the myocardial tissues of rats was significantly reduced. In the ischemia + PPG group, the TNF-α, IL-1β and IL-6 levels in the serum were significantly increased, the expression of ICAM-1 mRNA was increased, although without a significant difference, and the expression of NF-κB was increased. The findings of the present study provide novel evidence for the dual effects of H₂S on acute myocardial ischemia injury via the modulation of inflammatory factors.

Effects of Thyroid Hormone Analogue and a Leukotrienes Pathway-Blocker on Reperfusion Injury Attenuation after Heart Transplantation

Background. Global myocardial ischemia reperfusion injury after heart transplantation is believed to impair graft function and aggravate both acute and chronic rejection episodes. Objectives. To assess the possible protective potential of MK-886 and 3,5-diiodothyropropionic acid DITPA against global myocardial ischemia reperfusion injury after heart transplantation. Materials and Methods. Adult albino rats were randomized into 6 groups as follows: group I sham group; group II, control group; groups III and IV, control vehicles (1,2); group V, MK-886 treated group. Donor rats received MK-886 30 min before transplantation, and the same dose was repeated for recipients upon reperfusion; in group VI, DITPA treated group, donors and recipients rats were pretreated with DITPA for 7 days before transplantation. Results. Both MK-886 and DITPA significantly counteract the increase in the levels of cardiac TNF-α, IL-1β, and ICAM-1 and plasma level of cTnI (P < 0.05). Morphologic analysis showed that both MK-886 and DITPA markedly improved (P < 0.05) the severity of cardiac injury in the heterotopically transplanted rats. Conclusions. The results of our study reveal that both MK-886 and DITPA may ameliorate global myocardial ischemia reperfusion injury after heart transplantation via interfering with inflammatory pathway.

Defibrotide: properties and clinical use of an old/new drug

The drug named defibrotide (DFT) has been studied for many years. It has been shown to possess many activities: profibrinolytic, antithrombotic-thrombolytic, antiischemic (heart, liver, kidney, skin, brain), antishock, antiatherosclerotic, antirejection and anti-angiogenic. The previously displayed activities, as antithrombotic, profibrinolytic and anti-inflammatory, suggested its use in vascular disorders, as in the treatment of peripheral obliterative arterial disease and in thrombophlebitis. Some years after, the use of DFT in hepatic veno-occlusive disease has been also proposed. Even if DFT was considered for long time a multi-target drug, now it could be considered on the whole as a drug able to protect endothelium against activation. The present work reviews the more important experimental and clinical studies performed to detect DFT effects.

Long-term, up to 18 months, protective effects of the angiotensin II receptor blocker telmisartan on Epirubin-induced inflammation and oxidative stress assessed by serial strain rate

PURPOSE

The primary objective of the present study was to show the long lasting cardioprotective activity, at different time-points, up to 18 month-follow-up, of telmisartan in preserving the systolic function (assessed as Strain Rate-SR) in cancer patients treated with EPI both in the adjuvant and metastatic setting; the secondary objective was to confirm the correlation of the cardioprotective activity of telmisartan with a reduction of inflammation and oxidative stress induced by EPI.

METHODS

Phase II single blind placebo-controlled randomized trial. Sample size 50 patients per arm: based on a pre-planned interim analysis for early stopping rules, the study was discontinued for ethical reasons at 49 patients. Cardiovascular disease-free patients with cancer at different sites eligible for EPI-based treatment randomized to: telmisartan n = 25 or placebo n = 24. Echocardiography Tissue Doppler imaging (TDI) strain and strain rate was performed, serum levels of proinflammatory cytokines (IL-6, TNF-α) and oxidative stress (reactive oxygen species, ROS) were assessed at baseline, every 100 mg/m(2) EPI dose and at 6-, 12- and 18-month follow-up (FU).

RESULTS

Significant SR peak reduction in both arms was observed at t2 (cumulative dose EPI 200 mg/m(2)) vs t0. Conversely, at t3, t4, 6-, 12- and 18-month FU SR increased towards normal range in the telmisartan arm, while in the placebo arm SR remained significantly lower. Differences between SR changes in the placebo and telmisartan arm were significant from t3 up to 18 month-FU. IL-6 and ROS increased significantly in the placebo arm at t2 but did not change in the telmisartan arm. A significant (p < 0.05) correlation between changes of SR vs IL-6 and ROS was observed.

CONCLUSIONS

Our results suggest that the protective effect of telmisartan is long lasting, probably by ensuring a permanent (at least up to 18-month FU) defense against chronic or late-onset types of anthracycline-induced cardiotoxicity.

Adora2b signaling on bone marrow derived cells dampens myocardial ischemia-reperfusion injury

BACKGROUND

Cardiac ischemia-reperfusion (I-R) injury represents a major cause of cardiac tissue injury. Adenosine signaling dampens inflammation during cardiac I-R. The authors investigated the role of the adenosine A2b-receptor (Adora2b) on inflammatory cells during cardiac I-R.

METHODS

To study Adora2b signaling on inflammatory cells, the authors transplanted wild-type (WT) bone marrow (BM) into Adora2b(-/-) mice or Adora2b(-/-) BM into WT mice. To study the role of polymorphonuclear leukocytes (PMNs), neutrophil-depleted WT mice were treated with an Adora2b agonist. After treatments, mice were exposed to 60 min of myocardial ischemia and 120 min of reperfusion. Infarct sizes and troponin I concentrations were determined by triphenyltetrazolium chloride staining and enzyme-linked immunosorbent assay, respectively.

RESULTS

Transplantation of WT BM into Adora2b(-/-) mice decreased infarct sizes by 19 ± 4% and troponin I by 87.5 ± 25.3 ng/ml (mean ± SD, n = 6). Transplantation of Adora2b(-/-) BM into WT mice increased infarct sizes by 20 ± 3% and troponin I concentrations by 69.7 ± 17.9 ng/ml (mean ± SD, n = 6). Studies on the reperfused myocardium revealed PMNs as the dominant cell type. PMN depletion or Adora2b agonist treatment reduced infarct sizes by 30 ± 11% or 26 ± 13% (mean ± SD, n = 4); however, the combination of both did not produce additional cardioprotection. Cytokine profiling showed significantly higher cardiac tumor necrosis factor α concentrations in Adora2b(-/-) compared with WT mice (39.3 ± 5.3 vs. 7.5 ± 1.0 pg/mg protein, mean ± SD, n = 4). Pharmacologic studies on human-activated PMNs revealed an Adora2b-dependent tumor necrosis factor α release.

CONCLUSION

Adora2b signaling on BM-derived cells such as PMNs represents an endogenous cardioprotective mechanism during cardiac I-R. The authors' findings suggest that Adora2b agonist treatment during cardiac I-R reduces tumor necrosis factor α release of PMNs, thereby dampening tissue injury.

Long-term protective effects of the angiotensin receptor blocker telmisartan on epirubicin-induced inflammation, oxidative stress and myocardial dysfunction

Chronic inflammation, oxidative stress and the renin-angiotensin system (RAS) play a significant role in chemotherapy-induced cardiotoxicity (CTX). Telmisartan (TEL), an antagonist of the angiotensin II type-1 receptor, was found to reduce anthracycline (ANT)-induced CTX. We carried out a phase II placebo (PLA)-controlled randomized trial to assess the possible role of TEL in the prevention of cardiac subclinical damage induced by epirubicin (EPI). Forty-nine patients (mean age ± SD, 53.0±8 years), cardiovascular disease-free with cancer at different sites and eligible for EPI-based treatment, were randomized to one of two arms: TEL n=25; PLA n=24. A conventional echocardiography equipped with Tissue Doppler imaging, strain and strain rate (SR) was performed, and serum levels of proinflammatory cytokines, IL-6 and TNF-α, and oxidative stress parameters, reactive oxygen species (ROS) and glutathione peroxidase were determined. All assessments were carried out at baseline, after every 100 mg/m(2) of EPI dose and at the 12-month follow-up (FU). A significant reduction in the SR peak both in the TEL and PLA arms was observed at t(2) (cumulative dose of 200 mg/m(2) of EPI) in comparison to t(0). Conversely, at t(3) (300 mg/m(2) EPI), t(4) (400 mg/m(2) EPI) and the 12-month FU, the SR increased reaching the normal range only in the TEL arm, while in the PLA arm the SR remained significantly lower as compared to t(0) (baseline). The differences between SR changes in the PLA and TEL arms were significant from 300 mg/m(2) EPI (t(3)) up to the 12-month FU. Serum levels of IL-6 increased significantly in the PLA arm at 200 mg/m(2) EPI (t(2)) in comparison to baseline, but remained unchanged in the TEL arm. The same trend was demonstrated for ROS levels which significantly increased at t(2) vs. baseline in the PLA arm, while remained unchanged in the TEL arm. The mean change in ROS and IL-6 at t(2) was significantly different between the two arms. In the present study, we confirmed at the 3-month FU a trend toward a decrease in ROS and IL-6 from t(2) in the PLA arm. Our results suggest that TEL is able to reverse acute (early) EPI-induced myocardial dysfunction and to maintain later a normal systolic function up to the 12-month FU. These effects are likely to be due to different mechanisms, RAS blockade and prevention of chronic inflammation/oxidative stress.

Direct relationship between levels of TNF-alpha expression and endothelial dysfunction in reperfusion injury

We previously found that myocardial ischemia/reperfusion (I/R) initiates expression of tumor necrosis factor-alpha (TNF) leading to coronary endothelial dysfunction. However, it is not clear whether there is a direct relationship between levels of TNF expression and endothelial dysfunction in reperfusion injury. We studied levels of TNF expression by using different transgenic animals expressing varying amounts of TNF in I/R. We crossed TNF overexpression (TNF(++/++)) with TNF knockout (TNF(-/-)) mice; thus we have a heterozygote population of mice with the expression of TNF "in between" the TNF(-/-) and TNF(++/++) mice. Mouse hearts were subjected to 30 min of global ischemia followed by 90 min of reperfusion and their vasoactivity before and after I/R was examined in wild type (WT), TNF(-/-), TNF(++/++) and TNF heterozygote (TNF(-/++), cross between TNF(-/-) and TNF(++/++)) mice. In heterozygote TNF(-/++) mice with intermediate cardiac-specific expression of TNF, acetylcholine-induced or flow-induced endothelial-dependent vasodilation following I/R was between TNF(++/++) and TNF(-/-) following I/R. Neutralizing antibodies to TNF administered immediately before the onset of reperfusion-preserved endothelial-dependent dilation following I/R in WT, TNF(-/++) and TNF(++/++) mice. In WT, TNF(-/++) and TNF(++/++) mice, I/R-induced endothelial dysfunction was progressively lessened by administration of free-radical scavenger TEMPOL immediately before initiating reperfusion. During I/R, production of superoxide (O(2) (.-)) was greatest in TNF(++/++) mice as compared to WT, TNF(-/++) and TNF(-/-) mice. Following I/R, arginase mRNA expression was elevated in the WT, substantially elevated in the TNF(-/++) and TNF(++/++) mice and not affected in the TNF(-/-) mice. These results suggest that the level of TNF expression determines arginase expression in endothelial cells during myocardial I/R, which is one of the mechanisms by which TNF compromises coronary endothelial function in reperfusion injury.

Tumor necrosis factor induces matrix metalloproteinases in cardiomyocytes and cardiofibroblasts differentially via superoxide production in a PI3Kgamma-dependent manner

Tumor necrosis factor (TNF) is an inflammatory cytokine that is upregulated in a number of cardiomyopathies. Adverse cardiac remodeling and dilation result from degradation of the extracellular matrix by matrix metalloproteinases (MMPs). We investigated whether TNF can directly trigger expression and activation of MMPs in cardiac cells. We compared MMP expression profile and activities between primary cultures of mouse neonatal cardiomyocytes and cardiofibroblasts and in cellular and extracellular compartments. In response to recombinant TNF (rTNF, 20 ng/ml), cardiomyocytes exhibited faster and more pronounced superoxide production compared with cardiofibroblasts, concomitant with increased expression of several MMPs. MMP9 levels increased more rapidly and about twofold more in cardiomyocytes than in cardiofibroblasts. TNF did not induce MMP2 expression. Expression of collagenases (MMP8, MMP12, MMP13, and MMP14) increased significantly, while total collagenase activity increased to a greater degree in conditioned medium of cardiomyocytes than in cardiofibroblasts. rTNF-mediated MMP expression and activation were dependent on superoxide production and were blocked by apocynin, an NADPH oxidase inhibitor. We identified phosphatidylinositol 3-kinase (PI3K)gamma as a key factor in TNF-mediated events since TNF-induced superoxide production, MMP expression, and activity were significantly suppressed in cardiomyocytes and cardiofibroblasts deficient in PI3Kgamma. We further demonstrated that the TNF-superoxide-MMP axis of events is in fact activated in heart disease in vivo. Wild-type and TNF(-/-) mice subjected to cardiac pressure overload revealed that TNF deficiency resulted in reduced superoxide levels, collagenase activities, PI3K activity, and fibrosis leading to attenuated cardiac dilation and dysfunction. Our study demonstrates that TNF triggers expression and activation of MMPs faster and stronger in cardiomyocytes than in cardiofibroblasts in a superoxide-dependent manner and via activation of PI3Kgamma, thereby contributing to adverse myocardial remodeling in disease.

Role of Reactive Oxygen Species in Tumor Necrosis Factor-alpha Induced Endothelial Dysfunction

Endothelial cell injury and dysfunction are the major triggers of pathophysiological processes leading to cardiovascular disease. Endothelial dysfunction (ED) has been implicated in atherosclerosis, hypertension, coronary artery disease, vascular complications of diabetes, chronic renal failure, insulin resistance and hypercholesterolemia. Although now recognized as a class of physiological second messengers, reactive oxygen species (ROS) are important mediators in cellular injury, specifically, as a factor in endothelial cell damage. Uncontrolled ROS production and/or decreased antioxidant activity results in a deleterious state referred to as 'oxidative stress'. A candidate factor in causing ROS production in endothelial cells is tumor necrosis factor alpha (TNF-α), a pleiotropic inflammatory cytokine. TNF-α has been shown to both be secreted by endothelial cells and to induce intracellular ROS formation. These observations provide a potential mechanism by which TNF-α may activate and injure endothelial cells resulting in ED. In this review, we focus on the relationship between intracellular ROS formation and ED in endothelial cells or blood vessels exposed to TNF-α to provide insight into the role of this important cytokine in cardiovascular disease.

The immune system and cardiac repair

Myocardial infarction is the most common cause of cardiac injury and results in acute loss of a large number of myocardial cells. Because the heart has negligible regenerative capacity, cardiomyocyte death triggers a reparative response that ultimately results in formation of a scar and is associated with dilative remodeling of the ventricle. Cardiac injury activates innate immune mechanisms initiating an inflammatory reaction. Toll-like receptor-mediated pathways, the complement cascade and reactive oxygen generation induce nuclear factor (NF)-kappaB activation and upregulate chemokine and cytokine synthesis in the infarcted heart. Chemokines stimulate the chemotactic recruitment of inflammatory leukocytes into the infarct, while cytokines promote adhesive interactions between leukocytes and endothelial cells, resulting in transmigration of inflammatory cells into the site of injury. Monocyte subsets play distinct roles in phagocytosis of dead cardiomyocytes and in granulation tissue formation through the release of growth factors. Clearance of dead cells and matrix debris may be essential for resolution of inflammation and transition into the reparative phase. Transforming growth factor (TGF)-beta plays a crucial role in cardiac repair by suppressing inflammation while promoting myofibroblast phenotypic modulation and extracellular matrix deposition. Myofibroblast proliferation and angiogenesis result in formation of highly vascularized granulation tissue. As the healing infarct matures, fibroblasts become apoptotic and a collagen-based matrix is formed, while many infarct neovessels acquire a muscular coat and uncoated vessels regress. Timely resolution of the inflammatory infiltrate and spatial containment of the inflammatory and reparative response into the infarcted area are essential for optimal infarct healing. Targeting inflammatory pathways following infarction may reduce cardiomyocyte injury and attenuate adverse remodeling. In addition, understanding the role of the immune system in cardiac repair is necessary in order to design optimal strategies for cardiac regeneration.

Nonviral approaches for targeted delivery of plasmid DNA and oligonucleotide

Successful gene therapy depends on the development of efficient delivery systems. Although pDNA and ODN are novel candidates for nonviral gene therapy, their clinical applications are generally limited owing to their rapid degradation by nucleases in serum and rapid clearance. A great deal of effort had been devoted to developing gene delivery systems, including physical methods and carrier-mediated methods. Both methods could improve transfection efficacy and achieve high gene expression in vitro and in vivo. As for carrier-mediated delivery in vivo, since gene expression depends on the particle size, charge ratio, and interaction with blood components, these factors must be optimized. Furthermore, a lack of cell-selectivity limits the wide application to gene therapy; therefore, the use of ligand-modified carriers is a promising strategy to achieve well-controlled gene expression in target cells. In this review, we will focus on the in vivo targeted delivery of pDNA and ODN using nonviral carriers.

Proteasome inhibitor attenuates skeletal muscle reperfusion injury by blocking the pathway of nuclear factor-kappaB activation

BACKGROUND

Nuclear factor-kappaB is a key transcriptional factor in the regulation of inflammatory factors that are involved in tissue reperfusion injury, but conflicting data have been presented in the literature. The proteasome regulates proteins that control cell-cycle progression and apoptosis, and inhibition of the proteasome has been shown to reduce nuclear factor-kappaB activation and reperfusion injury. Although bortezomib is a potent proteasome inhibitor, its role in skeletal muscle reperfusion injury has not been documented, and its effects on the regulation of inflammatory factors in reperfused tissue are unclear. In this study, the authors investigated the role of nuclear factor-kappaB in skeletal muscle reperfusion injury and the effect of bortezomib (a proteasome inhibitor) on reperfusion injury.

METHODS

Pedicled cremaster muscle flaps from bortezomib-treated and phosphate-buffered saline-treated control mice were subjected to 4.5 hours of ischemia and 90 minutes of reperfusion.

RESULTS

During reperfusion, arterial diameters and blood flow recovered earlier and more completely in bortezomib-treated muscle than in controls. Compared with controls, Western blot analysis demonstrated a significant reduction in degradation of nuclear factor-kappaB inhibitory protein and expression of inducible nitric oxide synthase protein in bortezomib-treated muscle at the end of reperfusion. Immunohistochemistry showed decreased nuclear factor-kappaB p65-binding activity and down-regulated protein expression of intercellular adhesion molecule-1 and nitrotyrosine, accompanied by less muscle edema and inflammation as proven by histologic examination.

CONCLUSIONS

Bortezomib effectively blocks nuclear factor-kappaB activation in attenuating muscle reperfusion injury through inhibiting nuclear factor-kappaB inhibitory protein degradation. Therefore, inhibition of proteasome activity may provide a novel therapeutic strategy for the treatment of skeletal muscle reperfusion injury.

Cardioplegic ischemia or reperfusion: which is a main trigger for tumor necrosis factor production?

BACKGROUND

Tumor necrosis factor alpha (TNF-alpha) is a key cytokine in the pathogenesis of ischemia-reperfusion injury (I/R) that also possesses negative inotropic and direct cardiotoxic effects. We investigated whether myocardial ischemia and/or reperfusion is the trigger for TNF-alpha synthesis and whether TNF-alpha release is time dependent.

METHODS

Isolated rat hearts undergoing 30 min of coronary perfusion with modified Krebs-Henseleit solution followed by cardioplegic arrest for 60 min of global cardioplegic normothermic ischemia (GCI) and 30 min of reperfusion using a modified Langendorff model. Myocardial TNF-mRNA expression and TNF-alpha protein levels in effluent from the coronary sinus were measured at baseline and then after 15, 30, and 60 min of GCI and after 10 and 30 min of reperfusion.

RESULTS

GCI induced myocardial TNF-alpha mRNA expression and elevation protein TNF-alpha levels in a time-dependent manner after 30 min of ischemia from 78+/-17 pg/ml to 915+/-287 pg/ml after 60 min (p<0.0015). Reperfusion did not cause time-dependent increase of TNF-alpha synthesis and release but was accompanied by progressive decrease of left ventricular (LV) function. There was a correlation between TNF-alpha protein levels and depression of LV function immediately after GCI but not with TNF-alpha protein levels at 30 min of reperfusion.

CONCLUSION

This study demonstrated that myocardial ischemia rather than reperfusion is the main trigger for time-dependent TNF-alpha synthesis. Depression of LV function during reperfusion correlated significantly only with TNF-alpha levels at the end of GCI.

TNFα is required to confer protection in an in vivo model of classical ischaemic preconditioning

Although Tumor Necrosis Factor alpha (TNFalpha) is used as a preconditioning mimetic in vitro, its role in ischaemic preconditioning (IPC) has not been clearly defined. Here, we propose to use an in vivo model (that takes into account the activation of leukocytes which may affect levels of TNFalpha) to demonstrate that i) TNFalpha acts as a trigger in IPC and ii) the dose-dependent nature of this cardioprotective effect of TNFalpha. Male Wistar rats were subjected to 30 min of left coronary artery occlusion (index ischaemia), followed by 24 h reperfusion. In the presence or absence of a soluble TNFalpha receptor (sTNFalpha-R), preconditioning was induced by 3 cycles of ischaemia (3 min)/reperfusion (5 min) (IPC) or various doses (0.05-4 microg/kg) of exogenous TNFalpha. Following 24 h reperfusion, infarct size (IS, expressed as % of the area at risk (AAR)) was assessed. Tissue levels of TNFalpha from the AAR, following IPC and TNFalpha stimulus were determined using Western Blot. IPC caused decrease in IS (4.5+/-1.3% vs 30.8+/-4.3% in ischaemic rats; P<0.001) and increase of TNFalpha levels following the IPC stimulus. The protective effect of IPC was abrogated in the presence of the sTNFalpha-R. In addition, exogenous TNFalpha dose-dependently reduced IS with maximal protection at a dose of 0.1 microg/kg (IS=12.6%, P<0.01 vs ischaemic). In conclusion our data provide strong evidence for a role of TNFalpha during the trigger phase of IPC. In addition, exogenous TNFalpha mimics IPC by providing a dose-dependent cardioprotective effect against ischaemia-reperfusion injury in vivo.

Status of the endothelium-derived hyperpolarizing factor pathway in coronary arteries after heterotopic heart transplantation

BACKGROUND

After the first year of transplantation, the major limitation to long-term survival is the development of graft coronary vasculopathy, characterized by a pathologic activation of the endothelium with an attendant loss of its regulatory properties on homeostasis of the vascular wall. The present study was designed to evaluate the integrity of coronary vascular relaxations attributed to the endothelium-derived hyperpolarizing factor (EDHF) and to study hyperpolarization of smooth muscle cells after heterotopic heart transplantation.

METHODS

Six weeks after heart transplantation in a porcine model, vascular reactivity studies of control, native and allograft epicardial coronary artery rings were performed in standard organ chamber experiments. Moreover, membrane potential measurements were made with intracellular microelectrodes in rings of native and allograft coronary arteries.

RESULTS

There was a significant decrease in endothelium-dependent relaxations to 5-hydroxytryptamine (5-HT), high doses of bradykinin (BK) alone and BK plus N-omega-nitro-L-arginine (L-NNA) in rings from allograft compared to native, whereas the variation was significantly increased in response to cromakalim, a K(+)-ATP channel opener. Electrical and mechanical recordings showed no alteration in the resting membrane potential of smooth muscle cells, depolarization during contraction to prostaglandin F(2alpha) (PGF(2alpha)), or hyperpolarization in the presence of BK + L-NNA in rings of allograft vs native.

CONCLUSIONS

In this swine model of heart transplantation, part of the reduction in endothelium-dependent relaxations to BK may be attributed to an alteration in the activity of EDHF. This impairment of EDHF-mediated relaxations may compound the endothelial dysfunction preceding the development of coronary graft vasculopathy.

Inhibition of TNF-α Reduces Myocardial Injury and Proinflammatory Pathways Following Ischemia-Reperfusion in the Dog

We examined whether tumor necrosis factor-alpha (TNF-alpha) promotes postischemic inflammation and myocardial injury via activation of nuclear factor kappa B (NFkappaB) in an in vivo canine model. Isoflurane-anesthetized dogs underwent closed-chest balloon occlusion of the anterior descending coronary artery for 90 minutes, followed by reperfusion for 3 hours. Dogs randomly received a soluble TNF inhibitor (etanercept, 0.5 mg/kg intravenously) or saline before occlusion. Collateral blood flow and risk region size (RISK) were measured with radioactive microspheres, infarct size (INF) was measured by triphenyltetrazolium chloride staining, inflammation was measured by tissue myeloperoxidase (MPO) activity, intercellular adhesion molecular-1 (ICAM-1) messenger ribonucleic acid (mRNA) was measured by Northern blotting, and ICAM-1 protein expression was measured by Western blotting. NFkappaB activation was measured in nuclear extracts by electrophoretic mobility shift assays. INF/RISK was significantly smaller in the etanercept group than in the saline control group after adjusting for collateral flow (P < 0.009 by analysis of covariance, mean reduction in INF/RISK = 40%, 0.32 +/- 0.09 versus 0.53 +/- 0.09). MPO activity, ICAM-1 mRNA and protein expression, and NFkappaB binding activity were all significantly reduced in the etanercept group. Administration of a soluble TNF-alpha inhibitor reduced NFkappaB activation, ICAM-1 upregulation, and myocardial injury following ischemia-reperfusion. TNF-alpha appears to play a significant role in vivo in the genesis of postischemic inflammation.

Deficiency of TNFR1 protects myocardium through SOCS3 and IL-6 but not p38 MAPK or IL-1beta

Tumor necrosis factor-alpha (TNF-alpha) plays an important role in the development of heart failure. There is a direct correlation between myocardial function and myocardial TNF levels in humans. TNF may induce local inflammation to exert tissue injury. On the other hand, suppressors of cytokine signaling (SOCS) proteins have been shown to inhibit proinflammatory signaling. However, it is unknown whether TNF mediates myocardial inflammation via STAT3/SOCS3 signaling in the heart and, if so, whether this effect is through the type 1 55-kDa TNF receptor (TNFR1). We hypothesized that TNFR1 deficiency protects myocardial function and decreases myocardial IL-6 production via the STAT3/SOCS3 pathway in response to TNF. Isolated male mouse hearts (n = 4/group) from wild-type (WT) and TNFR1 knockout (TNFR1KO) were subjected to direct TNF infusion (500 pg.ml(-1).min(-1) x 30 min) while left ventricular developed pressure and maximal positive and negative values of the first derivative of pressure were continuously recorded. Heart tissue was analyzed for active forms of STAT3, p38, SOCS3 and SOCS1 (Western blot analysis), as well as IL-1beta and IL-6 (ELISA). Coronary effluent was analyzed for lactate dehydrogenase (LDH) activity. As a result, TNFR1KO had significantly better myocardial function, less myocardial LDH release, and greater expression of SOCS3 (percentage of SOCS3/GAPDH: 45 +/- 4.5% vs. WT 22 +/- 6.5%) after TNF infusion. TNFR1 deficiency decreased STAT3 activation (percentage of phospho-STAT3/STAT3: 29 +/- 6.4% vs. WT 45 +/- 8.8%). IL-6 was decreased in TNFR1KO (150.2 +/- 3.65 pg/mg protein) versus WT (211.4 +/- 26.08) mice. TNFR1 deficiency did not change expression of p38 and IL-1beta following TNF infusion. These results suggest that deficiency of TNFR1 protects myocardium through SOCS3 and IL-6 but not p38 MAPK or IL-1beta.

Insights from knock-out models concerning postischemic release of TNFalpha from isolated mouse hearts

The inflammatory cytokine tumor necrosis factor alpha (TNFalpha) is controversially discussed in ischemia/reperfusion damage of the heart. Purpose of this study was to elucidate cellular sources of TNFalpha and parameters which possibly influence its release in the heart following ischemia. Isolated hearts of mice were subjected to 15 min of global ischemia and 90 min of reperfusion. We employed hearts of various mice knock-out strains (interleukin-6(-/-), matrix metalloprotease-7(-/-), mast-cell deficient WBB6F1-Kit(W)/Kit(W-v), TNF-R1(-/-)) and wildtype mice, the latter perfused without and with infusion of cycloheximide or TNFalpha-cleaving-enzyme inhibitor (TAPI-2). Normoxic control hearts showed basal release of TNFalpha during the whole experiment. Immunohistology identified cardiac mast cells, macrophages and endothelial cells as main sources. TNFalpha release was stimulated during postischemic reperfusion, occurring in a two-peak pattern: directly after ischemia (0-10 min) and again after 60-90 min. The first peak mainly reflects tissue washout of TNFalpha accumulated during ischemia. The second, protracted peak arose continuously from the basal level and was abolished by protein synthesis inhibitor cycloheximide. Both properties are characteristic for de novo synthesis of TNFalpha, e.g., in cardiac muscle cells. However, immunohistological staining for TNFalpha failed in cardiomyocytes after 90 min of reperfusion. In contrast to hearts of TNF-R1(-/-) and Kit(W/W-v)-mice, those of IL-6(-/-) and MMP-7(-/-) mice lacked the late TNFalpha peak. TAPI did not suppress release of TNFalpha. While autostimulation via TNF-R1 also does not seem obligatory and mast cell can be ignored as source of the second peak, IL-6 may support de novo synthesis of TNFalpha. Additionally, TNFalpha release may essentially involve cleavage of membrane bound TNFalpha by MMP-7.

The mechanistic basis of infarct healing

Myocardial infarction triggers an inflammatory cascade that results in healing and replacement of the damaged tissue with scar. Cardiomyocyte necrosis triggers innate immune mechanisms eliciting Toll-like receptor- mediated responses, activating the complement cascade and generating reactive oxygen species. Subsequent activation of NF-kappaB is a critical element in the regulation of cytokine, chemokine, and adhesion molecule expression in the ischemic myocardium. Chemokine induction mediates leukocyte recruitment in the myocardium. Pleiotropic proinflammatory cytokines, such as TNF-alpha, IL-1, and IL-6, are also upregulated in the infarct and exert a wide range of effects on a variety of cell types. Timely repression of proinflammatory gene synthesis is crucial for optimal healing; IL-10 and TGF-beta-mediated pathways may be important for suppression of chemokine and cytokine expression and for resolution of the leukocytic infiltrate. In addition, TGF-beta may be critically involved in inducing myofibroblast differentiation and activation, promoting extracellular matrix protein deposition in the infarcted area. The composition of the extracellular matrix plays an important role in regulating cell behavior. Both structural and matricellular proteins modulate cell signaling through interactions with specific surface receptors. The molecular and cellular changes associated with infarct healing directly influence ventricular remodeling and affect prognosis in patients with myocardial infarction.

Gender differences in injury induced mesenchymal stem cell apoptosis and VEGF, TNF, IL-6 expression: role of the 55 kDa TNF receptor (TNFR1)

Concomitant pro- and anti-inflammatory properties of bone marrow stem cells (BMSC) may be an important aspect of their ability to heal injured tissue. However, very few studies have examined whether gender differences exist in BMSC function. Indeed, it remains unknown whether gender differences exist in BMSC function and ability to resist apoptosis, and if so, whether TNF receptor 1 (TNFR1) plays a role in these differences. We hypothesized that TNFR1 ablation equalizes gender differences in bone marrow mesenchymal stem cell (MSC) apoptosis, as well as expression of vascular endothelial growth factor (VEGF), TNF and interleukin (IL)-6. Mouse MSCs from male wild type (WT), female WT, male TNFR1 knockouts (TNFR1KO) and female TNFR1KO were stressed by endotoxin 200 ng/ml or 1 h hypoxia. MSC activation was determined by measuring VEGF, TNF and IL-6 production (ELISA). Differences considered significant if p<0.05. LPS and hypoxia resulted in significant activation in all experimental groups compared to controls. Male WT demonstrated significantly greater TNF and IL-6 and significantly less VEGF release than female WT MSCs. However, release of TNF, IL-6 and VEGF in male TNFR1 knockouts differed from male WT, but was not different from female WT MSCs. Similarly apoptosis in hypoxic male TNFRIKO differed from male WT, but it was not different from apoptosis from WT female. Female WT did not differ in TNF, IL-6 and VEGF release compared to female TNFR1KO. Gender differences exist in injury induced BMSC VEGF, TNF and IL-6 expression. TNFR1 may autoregulate VEGF, TNF and IL-6 expression in males more than females. MSCs are novel therapeutic agents for organ protection, but further study of the disparate expression of VEGF, TNF and IL-6 in males and females as well as the role of TNFR1 in these gender differences is necessary to maximize this protection.

Effect of cardioplegic and organ preservation solutions and their components on coronary endothelium-derived relaxing factors

Cardioplegic (and organ preservation) solutions were initially designed to protect the myocardium (cardiac myocytes) during cardiac operation (and heart transplantation). Because of differences between cardiac myocytes and vascular (endothelial and smooth muscle) cells in structure and function, the solutions may have an adverse effect on coronary vascular cells. However, such effect is often complicated by many other factors such as ischemia-reperfusion injury, temperature, and perfusion pressure or duration. To evaluate the effect of a solution on the coronary endothelial function, a number of points should be taken into consideration. First, the overall effect on endothelium should be identified. Second, the effect of the solution on the individual endothelium-derived relaxing factors (nitric oxide, prostacyclin, and endothelium-derived hyperpolarizing factor) must be distinguished. Third, the effect of each major component of the solution should be investigated. Lastly, the effect of a variety of new additives in the solution may be studied. Based on available literature these issues are reviewed to provide information for further development of cardioplegic or organ preservation solutions.

Inhibitory effects of edaravone on the production of tumor necrosis factor-α in the isolated heart undergoing ischemia and reperfusion

We evaluated the effects of edaravone, a hydroxyl radical scavenging agent, on the production of tumor necrosis factor-alpha (TNF-alpha) in myocardium, and the release of TNF-alpha and P-selectin from myocardium after ischemia-reperfusion injury in isolated Langendorff-perfused rat hearts. Cardiodynamic function at stable points during perfusion and 5, 15, 30, and 60 min after the initiation of reperfusion was evaluated by left ventricular developed pressure, rate of increase in left ventricular pressure and rate of decrease in ventricular pressure, coronary flow, and heart rate. At 60 min after the initiation of reperfusion, myocardial infarct size was estimated microscopically using triphenyltetrazolium chloride staining, and expression of TNF-alpha in myocardium was detected by Western blot and immunohistochemistry. At the same time points as the measurement of cardiodynamic function, TNF-alpha and the soluble form of P-selectin in coronary effluent were measured by enzyme immunoassay. At all time points during reperfusion, edaravone markedly improved cardiodynamic function and reduced myocardial infarct size in comparison to the control. In myocardium in the control, TNF-alpha was detected in the endothelial cells and other cells bearing some resemblance to interstitial cells and monocyte cells. Edaravone suppressed this cytokine expression in the corresponding sites. P-selectin as well as TNF-alpha was found in the coronary effluent of the control, and edaravone significantly decreased soluble P-selectin levels in comparison to the control (P < 0.01). Edaravone might have protective effects on cardiac function through reduction of infarct size via decrease of production of TNF-alpha in myocardium induced by ischemia-reperfusion injury and through reduction of the release of adhesion molecules such as P-selectin from vascular endothelial cells.

TNFR1 mediates increased neuronal membrane EAAT3 expression after in vivo cerebral ischemic preconditioning

A short ischemic event (ischemic preconditioning) can result in subsequent resistance to severe ischemic injury (ischemic tolerance). Glutamate is released after ischemia and produces cell death. It has been described that after ischemic preconditioning, the release of glutamate is reduced. We have shown that an in vitro model of ischemic preconditioning produces upregulation of glutamate transporters which mediates brain tolerance. We have now decided to investigate whether ischemic preconditioning-induced glutamate transporter upregulation takes also place in vivo, its cellular localization and the mechanisms by which this upregulation is controlled. A period of 10 min of temporary middle cerebral artery occlusion was used as a model of ischemic preconditioning in rat. EAAT1, EAAT2 and EAAT3 glutamate transporters were found in brain from control animals. Ischemic preconditioning produced an up-regulation of EAAT2 and EAAT3 but not of EAAT1 expression. Ischemic preconditioning-induced increase in EAAT3 expression was reduced by the TNF-alpha converting enzyme inhibitor BB1101. Intracerebral administration of either anti-TNF-alpha antibody or of a TNFR1 antisense oligodeoxynucleotide also inhibited ischemic preconditioning-induced EAAT3 up-regulation. Immunohistochemical studies suggest that, whereas the expression of EAAT3 is located in both neuronal cytoplasm and plasma membrane, ischemic preconditioning-induced up-regulation of EAAT3 is mainly localized at the plasma membrane level. In summary, these results demonstrate that in vivo ischemic preconditioning increases the expression of EAAT2 and EAAT3 glutamate transporters the upregulation of the latter being at least partly mediated by TNF-alpha converting enzyme/TNF-alpha/TNFR1 pathway.

Tumor-Necrosis-Factor-.ALPHA.-Gene-Deficient Mice Have Improved Cardiac Function Through Reduction of Intercellular Adhesion Molecule-1 in Myocardial Infarction

BACKGROUND

Tumor necrosis factor (TNF)-alpha is linked to the pathogenesis of cardiovascular diseases, but how it affects myocardial infarction (MI), so the present study examined the effects of TNF-alpha and the involvement of intercellular adhesion molecule (ICAM)-1 on MI.

METHODS AND RESULTS

Left coronary arteries of C57BL/6 wild type (WT) and TNF-alpha knockout (KO) mice were ligated and the mice were killed 1, 3, and 7 days later. Fractional shortening on echocardiography of the KO mice was significantly higher than that of the WT mice from day 1 to 7 (p<0.01). The ICAM-1 mRNA in the infarcted area of the KO mice was significantly lower than that of the WT from day 1 (p<0.01) to 7. In immunohistochemistry, the expression of ICAM-1 was weaker in the KO than in the WT mice. The number of neutrophils in the KO mice peaked at day 1, but even this peak level failed to reach the levels in the infarcted (p<0.01) and peri-infarcted areas (p<0.05) in the WT. The number of macrophages in the KO mice peaked at day 7, but this peak level failed to reach the levels in the infarcted (p<0.01) and peri-infarcted areas (p<0.05) in the WT.

CONCLUSION

In a permanent occlusion model of MI TNF-alpha decreased cardiac function and ameliorated myocardial remodeling through the induction of ICAM-1.

Calpains: a physiological regulator of the endothelial barrier?

The intracellular protease calpain, abundant in endothelial cells (EC), is assumed to be inactive under physiological conditions but may account for Ca2+ -linked pathophysiological events. However, nonstimulated EC contained autolyzed, activated calpain. Adding 12-48 microM calpain inhibitor I (CI) or 0.5-1 microM of the novel, membrane-permeable conjugate of calpastatin peptide-penetratin (CPP) caused rapid rounding and retraction of cultured EC (phase contrast, capacitance) and translocation of Syk, Rac, and Rho to the membrane, signifying activation upon inhibition of calpain. Isolated hearts (guinea pig) perfused with 12 microM CI or 0.5 muM CPP developed coronary leak. We conclude that calpain is constitutively active in EC and regulates vascular permeability by governing cell-cell attachment.

Caffeic acid phenethyl ester possesses potent cardioprotective effects in a rabbit model of acute myocardial ischemia-reperfusion injury

Although great achievements have been made in elucidating the molecular mechanisms contributing to acute myocardial ischemia/reperfusion (I/R) injury, an effective pharmacological therapy to protect cardiac tissues from serious damage associated with acute myocardial infarction, coronary arterial bypass grafting surgery, or acute coronary syndromes has not been developed. We examined the in vivo cardioprotective effects of caffeic acid phenethyl ester (CAPE), a natural product with potent anti-inflammatory, antitumor, and antioxidant activities. CAPE was systemically delivered to rabbits either 60 min before or 30 min after surgically inducing I/R injury. Infarct dimensions in the area at risk were reduced by >2-fold ( P < 0.01) with CAPE treatment at either period. Accordingly, serum levels of normally cytosolic enzymes lactate dehydrogenase, creatine kinase (CK), MB isoenzyme of CK, and cardiac-specific troponin I were markedly reduced in both CAPE treatment groups ( P < 0.05) compared with the vehicle-treated control group. CAPE-treated tissues displayed significantly less cell death ( P < 0.05), which was in part due to inhibition of p38 mitogen-activated protein kinase activation and reduced DNA fragmentation often associated with caspase 3 activation ( P < 0.05). In addition, CAPE directly blocked calcium-induced cytochrome c release from mitochondria. Finally, the levels of inflammatory proteins IL-1β and TNF-α expressed in the area at risk were significantly reduced with CAPE treatment ( P < 0.05). These data demonstrate that CAPE has potent cardioprotective effects against I/R injury, which are mediated, at least in part, by the inhibition of inflammatory and cell death responses. Importantly, protection is conferred when CAPE is systemically administered after the onset of ischemia, thus demonstrating potential efficacy in the clinical scenario.

Adiponectin protects against myocardial ischemia-reperfusion injury through AMPK- and COX-2-dependent mechanisms

Obesity-related disorders are associated with the development of ischemic heart disease. Adiponectin is a circulating adipose-derived cytokine that is downregulated in obese individuals and after myocardial infarction. Here, we examine the role of adiponectin in myocardial remodeling in response to acute injury. Ischemia-reperfusion in adiponectin-deficient (APN-KO) mice resulted in increased myocardial infarct size, myocardial apoptosis and tumor necrosis factor (TNF)-alpha expression compared with wild-type mice. Administration of adiponectin diminished infarct size, apoptosis and TNF-alpha production in both APN-KO and wild-type mice. In cultured cardiac cells, adiponectin inhibited apoptosis and TNF-alpha production. Dominant negative AMP-activated protein kinase (AMPK) reversed the inhibitory effects of adiponectin on apoptosis but had no effect on the suppressive effect of adiponectin on TNF-alpha production. Adiponectin induced cyclooxygenase (COX)-2-dependent synthesis of prostaglandin E(2) in cardiac cells, and COX-2 inhibition reversed the inhibitory effects of adiponectin on TNF-alpha production and infarct size. These data suggest that adiponectin protects the heart from ischemia-reperfusion injury through both AMPK- and COX-2-dependent mechanisms.

Cyclosporine-induced coronary endothelial dysfunction: is tetrahydrobiopterin the solution?

BACKGROUND

Coronary endothelial dysfunction after heart transplantation is predictive of cardiac allograft vasculopathy. Immunosuppressive drugs, particularly cyclosporine may contribute to this dysfunction by a direct effect. Tetrahydrobiopterin (BH(4)) is a potent antioxidant and an essential cofactor of nitric oxide biosynthesis. The purpose of this study was to investigate whether BH(4) could reverse the endothelial dysfunction induced by cyclosporine.

METHODS

A previously described in vitro model of drug incubation in Krebs-bicarbonate solution (4 degrees C, 48 hours) of porcine epicardial coronary arteries was used. Coronary endothelial function studies were performed in organ chamber experiments after incubation with cyclosporine (10(-4) mol/L) in the presence or absence of 6-methyltetrahydropterin (MH(4) [0.1 mol/L], a BH(4) analog) to assess its effect on the cyclosporine-induced endothelial dysfunction.

RESULTS

The average doses of PGF2(alpha) required to attain 50% of the maximal contraction to KCl was significantly lower (P < .001) in the cyclosporine group (8.6 +/- 1.94 x 10(-6) mol/L) compared to the control group (24.8 +/- 5.2 x 10(-6) mol/L). Exposure to cyclosporine induced a significant decrease in endothelium-dependent relaxations to serotonin (5HT) (% E(max) [5HT]: 77% +/- 4%; P < .05). Addition of MH(4) significantly reversed this impaired response (% E(max) [5HT]: 62% +/- 4%; P < .05). No alterations of relaxation were observed with bradykinin in both groups. Endothelium-independent relaxations to sodium nitroprussiate were fully preserved.

CONCLUSIONS

These results suggest a significant protective role of BH(4) on coronary endothelial function following exposure to cyclosporine, which could reduce the incidence of endothelial dysfunction and cardiac allograft vasculopathy following cardiac transplantation.

A potential role for angiotensin II in obesity induced cardiac hypertrophy and ischaemic/reperfusion injury

BACKGROUND

The mechanisms for obesity induced myocardial remodelling and subsequent mechanical dysfunction are poorly understood. There is good evidence that angiotensin II and TNFalpha have strong growth promoting properties and are elevated with obesity. In addition, these two peptides may interact to exacerbate myocardial ischaemic/reperfusion injury.

HYPOTHESIS

Obesity increases systemic and myocardial renin-angiotensin system (RAS) activity and TNFalpha levels and contributes to obesity induced cardiac remodelling and ischaemic/reperfusion injury.

METHODS

Male Wistar rats were placed on a standard rat chow diet or cafeteria diet for 16 weeks. Two additional groups of rats received the respective diets and losartan (30 mg/ kg/d) in their drinking water. Hearts were perfused on the isolated working rat heart perfusion system and mechanical function was documented before and after 15 min normothermic total global ischaemia. Blood and myocardial samples were collected for angiotensin II, TNFalpha and NADPH oxidase activity determinations.

RESULTS

The rats on the cafeteria diet became obese compared to rats on the standard rat chow (438 +/- 5.9 g vs 393 +/- 7.3 g for control, p < 0.05). Obesity was associated with elevated serum angiotensin II (0.050 +/- 0.015 pmol/ml vs. 0.035 +/- 0.003 pmol/ml, p < 0.05) and TNFalpha levels (42.8 +/- 5.93 pg/ml vs. 13.18 +/- 2.50 pg/ml, p < 0.05), and increased heart to body weight ratios (3.1 +/- 0.04 mg/g vs. 2.8 +/- 0.03 mg/g, p < 0.05). Losartan had no effect on body weight but decreased basal myocardial angiotensin II and TNFAlpha levels as well as heart to body weight ratio in the obese and lean controls (2.5 +/- 0.05 mg/g and 2.6 +/- 0.04 mg/g relative to their controls, p < 0.05). Hearts from obese rats had lower reperfusion aortic outputs (AO) than their concurrent controls (18.42 +/- 1.17 ml/min vs. 27.8 +/- 0.83 ml/min, p < 0.05). Losartan improved aortic output recoveries in obese rats (23.0 +/- 1.71 ml/min, p < 0.05).

CONCLUSIONS

Obesity increased serum angiotensin II and TNFalpha levels, blood pressure, and heart weight to body weight ratios. These changes were associated with decreased basal and post-ischaemic myocardial mechanical function. Chronic AT(1) receptor antagonism prevented the adverse changes in heart weight, mechanical function and susceptibility to ischaemic/reperfusion injury. Although current data do not exclude additional mechanisms for obesity induced cardiac remodelling, they suggest that angiotensin II may contribute to obesity induced cardiac remodelling and ischaemic/reperfusion injury.

Role of cytokines in cardiovascular diseases: a focus on endothelial responses to inflammation

Complex cellular and inflammatory interactions are involved in the progress of vascular diseases. Endothelial cells, upon exposure to cytokines, undergo profound alterations of function that involve gene expression and de novo protein synthesis. The functional reprogramming of endothelial cells by cytokines is of importance especially in patients with chronic vascular inflammation. The intercellular network of dendritic cells, T-lymphocytes, macrophages and smooth muscle cells generates a variety of stimulatory cytokines [e.g. TNF-alpha (tumour necrosis factor-alpha), IL (interleukin)-1, IL-6 and IFN-gamma (interferon-gamma)] and growth factors that promote the development of functional and structural vascular changes. High concentrations of proinflammatory cytokines increase oxidative stress, down-regulate eNOS (endothelial nitric oxide synthase) bioactivity and induce endothelial cell apoptosis. Chemoattractant cytokines [e.g. VEGF (vascular endothelial growth factor), TGF-beta1 (transforming growth factor-beta1) and IL-8] are important regulators of inflammation-induced angiogenesis and are directly modulated by nitric oxide. This review will focus on the vascular mechanisms orchestrated by cytokines and summarizes the current knowledge concerning the contribution of cytokines to cardiovascular diseases.

Fluorescence imaging microscopy of cellular markers in ischemic vs non-ischemic cardiomyopathy after left ventricular unloading

BACKGROUND

The heart undergoes repair and initiates protective mechanisms via ventricular unloading. We examined the presence of 2 markers in pre-unloaded and post-unloaded human cardiac tissue that are important indicators of cardiac failure, tumor necrosis factor-alpha and inducible nitric oxide synthase. We also measured 2 nuclear transcription factors, NFkappaB50 and NFkappaB65, comparing quantities and localizations to determine if mechanical unloading reduced their presence, as these markers are also thought to be indicators of impending heart failure. Amounts and localizations in patients that had been diagnosed with either ischemic or non-ischemic cardiomyopathy were compared after mechanical unloading with a left ventricular assist device. To establish that unloading had been achieved, levels of atrial natriuretic protein were determined.

METHODS

Core biopsies were harvested at assist device implantation and removal. Fluorescence deconvolution microscopy image reconstructions of fluorescence probes were correlated with data obtained by western Blot and electrobility shift assays.

RESULTS

Statistically significant differences in localization and amounts of tumor necrosis factor and nitric oxide synthase were seen between pre- and post-assist device samples. Amounts of tumor necrosis factor and nitric oxide synthase in ischemic tissue were increased at the time of assist device removal, but decreased in dilated or idiomyopathic samples. Ventricular unloading resulted in reduced levels of natriuretic protein, with the greatest reduction being seen in ischemic tissue. Both NFkappaB50 and NFkappaB65 increased in ischemic tissue, but only NFkappaB50 in non-ischemic samples.

CONCLUSIONS

Changes in localization of the factors and altered levels of cytokine and nitric oxide synthase indicate that the heart switches to a "protective and repair" mode, and mechanical unloading allows this transition to occur. Observed changes were dependent on the etiology of the disease.

TNFR1 upregulation mediates tolerance after brain ischemic preconditioning

A short ischemic event (ischemic preconditioning (IPC)) can result in subsequent resistance to severe ischemic injury (ischemic tolerance (IT)). The expression and neuroprotective role of tumor necrosis factor (TNF-alpha) have been described in models of IPC and we have showed the participation of its processing enzyme, the TNF-alpha convertase enzyme (TACE) in this process. We have now decided to explore the expression and localization of TNF receptors (TNFR) as well as other signalling mechanisms involved in IT. A period of 10 mins of temporary middle cerebral artery occlusion (tMCAO) was used for focal IPC. To evaluate the ability of IPC to produce IT, permanent MCAO was performed 48 hours after IPC. Ischemic preconditioning produced a reduction in infarct volume, as we showed previously. Ischemic preconditioning caused upregulation of neuronal TNFR1 that was reduced by the selective TACE inhibitor BB1101. Intracerebral administration of TNFR1 antisense oligodeoxynucleotide, which caused a reduction in TNFR1 expression, inhibited the IPC-induced protective effect, showing that TNFR1 upregulation is implicated in IT. Moreover, treatment with BB1101, TNFR1 antisense and lactacystin-a specific proteasome inhibitor-blocked IPC-induced NF-kappaB. Immunohistochemical studies showed the expression of TACE and TNFR1 in neurons. In summary, these data show that IPC produces neuronal upregulation of TACE and TNFR1, and that the pathway TACE/TNF-alpha/TNFR1/NF-kappaB is involved in IT.

Ischemic preconditioning ameliorates microcirculatory disturbance through downregulation of TNF-alpha production in a rat cremaster muscle model

Ischemia-reperfusion (I/R) injury is a complex process involving the generation and release of inflammatory cytokines, and the accumulation and infiltration of neutrophils and macrophages, which disturbs the microcirculatory hemodynamics. Nonetheless, ischemic preconditioning (IPC) is known to produce immediate tolerance to subsequent prolonged I/R insults, although its underlying mechanism largely remains unknown. Our study investigated the role of the IkappaB-alpha-NF-kappaB-TNF-alpha (tumor necrosis factor-alpha) pathway in IPC's ability to ameliorate I/R-induced microcirculatory disturbances in rat cremaster muscle flaps. Male Sprague-Dawley rats were randomized (n = 8 per group) into 3 groups: a sham-operated control group, an I/R group (4 h of pudic epigastric artery ischemia followed by 2 h of reperfusion), and an IPC+I/R group (3 cycles of 10 min of ischemia followed by 10 min reperfusion before I/R). Intravital microscopy was used to observe leukocyte/endothelial cell interactions and quantify functional capillaries in cremaster muscles. I/R markedly increased the number of rolling, adhering, and migrating leukocytes. It was also observed that I/R significantly increased TNF-alpha expression in these injured tissues. On the other hand, IPC prevented I/R-induced increases in leukocyte rolling, adhesion, and transmigration. Moreover, TNF-alpha protein production and its mRNA expression were downregulated in the IPC group. Finally, I/R-induced IkappaB-alpha phosphorylation and NF-kappaB (p65) nuclear translocation were both suppressed by IPC. These results indicated that IPC attenuated NF-kappaB activation and subsequently reduced TNF-alpha expression, which resulted in the amelioration of microcirculatory disturbances in I/R-injured cremaster muscles.

TNF-alpha accounts for short-term persistence of oxidative status in rat brain after two weeks of repeated stress

Inducible nitric oxide synthase (NOS-2) accounts for the accumulation of oxidative and nitrosative mediators in brain after stress. To determine whether and when repeated exposure to immobilization stress leads to persistent oxidative status in rat brain, male Wistar rats were immobilized for 6 h/day for 7 or 14 days (S7, S14). Cerebral cortices were obtained immediately after the last session of stress or 1 day later. Stress increased NOS-2 activity after S7 or S14. This enzymatic activity returned to basal values 1 day after S7, but not 1 day after S14. Stress increased malondialdehyde (MDA) accumulation in cortex after S7 and S14. MDA levels returned to basal values 1 day after S7 but not 1 day after S14. In order to elucidate the possible mechanisms involved in this short-term persistence of oxidative status, brain levels of the cytokine tumour necrosis factor alpha (TNF-alpha) were determined. TNF-alpha levels did not increase after S7 or 1 day after S7, but increased after S14 and 1 day after S14. This was paralleled by an increase in TNF-alpha converting enzyme (TACE) activity in brain. When the increase in TNF-alpha at S14 was blocked by BB1101, an inhibitor of TACE, or its effects were blocked with anti-TNF-alpha, the accumulation of MDA and NOS-2 activity 1 day after S14 did not take place. These findings indicate that TACE and TNF-alpha account for stress-induced short-term persistence of NOS-2 activity and MDA accumulation after 14 days of repeated exposure and support a possible neuroprotective role for specific blockers of TNF-alpha in this situation.

Exogenous and Endogenous Nitric Oxide Donors Improve Post-Ischemic Tissue Oxygenation in Early Pancreatic Ischemia/Reperfusion Injury in the Rat

INTRODUCTION

In pancreatic ischemia/reperfusion (IR) injury (IRI) the role of nitric oxide (NO) is not completely understood. Using a rat model of normothermic in situ IRI, the effect of endogenous and exogenous NO donors on post-ischemic tissue oxygenation and tissue damage was investigated.

METHODS

IR was induced by 2-hour normothermic in situ ischemia of a pancreatic tail segment pedunculated on the splenic vessels with 2 h of reperfusion in an untreated, an L-arginine- and a sodium-nitroprusside-treated group (Wistar rats, n = 7/group). Animals without ischemia served as controls. Tissue oxygenation (pO(2ti)) was monitored using a pO2-sensitive Clark-type electrode. Histological investigation was performed following a semiquantitative score (edema, vacuolization, PMN infiltration, necrosis). Plasma lipase was another marker of organ damage.

RESULTS

The administration of L-arginine and sodium nitroprusside caused a significant amelioration of the decrease in pO2i) after reperfusion compared to IR animals (p < 0.05). Histological damage was also reduced in the NO donor groups (p < 0.05). After reperfusion, plasma lipase in the L-arginine-treated animals was significantly lower compared to IR and sodium nitroprusside (p < 0.05).

CONCLUSIONS

The administration of both endogenous and exogenous NO donors is protective in IRI of the rat pancreas which can be seen by an improvement in post-ischemic tissue oxygenation which indicates better nutritive tissue perfusion, amelioration of the histological tissue injury and, in L-arginine animals, lower lipase levels. NO donors could be useful in the prevention and reduction of the pancreatic IRI.

Protection against acute adriamycin-induced cardiotoxicity by garlic: role of endogenous antioxidants and inhibition of TNF-alpha expression

Background

Oxidative stress is the major etiopathological factor in adriamycin-induced cardiotoxicity. Relatively low amounts of endogenous antioxidant makes the heart vulnerable to oxidative stress-induced damage. Chronic oral administration of garlic has been reported to enhance the endogenous antioxidants of heart. We hypothesized that garlic-induced enhanced cardiac antioxidants may offer protection against acute adriamycin-induced cardiotoxicity.

Results

Rats were either administered freshly prepared garlic homogenate (250 and 500 mg/kg daily, orally, for 30 days) or probucol (cumulative dose, 120 mg/kg body weight divided in 12, i.p. over a period of 30 days) or double distilled water (vehicle), followed by a single dose of adriamycin (30 mg/kg i.p.). In the adriamycin group, increased oxidative stress was evidenced by a significant increase in myocardial TBARS (thiobarbituric acid reactive substances) and decrease in myocardial SOD (superoxide dismutase), catalase and GPx (glutathione peroxidase) activity. Histopathological studies showed focal as well as subendocardial myocytolysis with infiltration of macrophages, lymphocytes and edema. Immunocytochemistry showed marked expression of TNF-α (tumor necrosis factor-alpha) in the myocardium. Increase in myocardial TBARS and decrease in endogenous antioxidants by adriamycin was prevented significantly in the garlic treated rat hearts, which was comparable to the probucol-treated group. Histopathological evidence of protection was also evident in both garlic-treated and probucol-treated groups. Probucol, 250 mg/kg and 500 mg/kg of garlic reduced adriamycin induced TNF-α expression in the myocardium and was associated with reduced myocyte injury.

Conclusions

It is concluded that chronic garlic administration prevents acute adriamycin-induced cardiotoxicity and decreases myocardial TNF-α expression.