Characterization of a transient outward K+ current with inward rectification in canine ventricular myocytes

Targeting the vicious inflammation-oxidative stress cycle for the management of heart failure

Oxidative stress and inflammation are each implicated independently in the development and progression of heart failure. Their interaction, however, is also evident throughout the process from initial injury to cardiac remodeling and failure. In the failing heart, the linkage between excessive reactive oxygen species (ROS) and the cytokine elaboration is manifested in shared elements and cross-promotion within downstream signaling pathways. In spite of this, the failure of anticytokine immunotherapy and antioxidant therapy, which had previously shown promise, suggests that a more complete perspective of ROS-cytokine interaction is required. The present review focuses on two of the major cytokines that are demonstrably connected to oxidative stress--the pro-inflammatory tumor necrosis factor-alpha (TNF-alpha) and the anti-inflammatory interleukin-10 (IL-10)--and their interactions in cardiac remodeling and failure. It is proposed that an optimal balance between TNF-alpha and IL-10 may be of crucial importance in mitigating both inflammation and oxidative stress processes leading to heart failure.

Ocimum gratissimum Aqueous Extract Protects H9c2 Myocardiac Cells from H(2)O(2)-Induced Cell Apoptosis through Akt Signalling

Increased cell death of cardiomyocyte by oxidative stress is known to cause dysfunction of the heart. O. gratissimum is one of the more well-known medicinal plants among the Ocimum species and widely used in treatment of inflammatory diseases. In this study, we hypothesized that aqueous extract of O. gratissimum leaf (OGE) may protect myocardiac cell H9c2 from oxidative injury by hydrogen peroxide (H₂O₂). Our results revealed that OGE pretreatment dose-dependently protects H9c2 cells from cell death when exposed to H₂O₂. Additionally, DNA condensation induced by H₂O₂ was also reduced by OGE pretreatment, suggesting that Ocimum gratissimum extract may attenuate H₂O₂-induced chromosome damage. Further investigation showed that OGE pretreatment inhibited H₂O₂-induced activation of caspase-3 and caspase-9, as well as H₂O₂-induced upregulation of proapoptotic Apaf-1 and the release of cytosolic cytochrome c, but has little effect on the activation of caspase-8. Additionally, OGE pretreatment significantly upregulated Bcl-2 expression and Akt phosphorylation, and slightly affected the phosphorylation of mitogen-activated protein kinases including p38 MAPK and JNK. Taken together, our findings revealed that Ocimum gratissimum extract effectively inhibited the mitochondrial pathway and upregulated Bcl-2 expression, which may be important in protecting H9c2 cells from H₂O₂-induced cell death.

Novel insights for systemic inflammation in sepsis and hemorrhage

The inflammatory responses in sepsis and hemorrhage remain a major cause of death. Clinically, it is generally accepted that shock in sepsis or hemorrhage differs in its mechanisms. However, the recognition of inflammatory cytokines as a common lethal pathway has become consent. Proinflammatory cytokines such as tumor necrosis factor (TNF) or high-mobility group box1 (HMGB1) are fanatically released and cause lethal multiorgan dysfunction. Inhibition of these cytokines can prevent the inflammatory responses and organ damage. In seeking potential anti-inflammatory strategies, we reported that ethyl pyruvate and alpha7 nicotinic acetylcholine receptor (alpha7nAChR) agonists effectively restrained cytokine production to provide therapeutic benefits in both experimental sepsis and hemorrhage. Here, we review the inflammatory responses and the anti-inflammatory strategies in experimental models of sepsis and hemorrhage, as they may have a consistent inflammatory pathway in spite of their different pathophysiological processes.

Diabetic cardiomyopathy: signaling defects and therapeutic approaches

Diabetes mellitus is the world's fastest growing disease with high morbidity and mortality rates, predominantly as a result of heart failure. A significant number of diabetic patients exhibit diabetic cardiomyopathy; that is, left ventricular dysfunction independent of coronary artery disease or hypertension. The pathogenesis of diabetic cardiomyopathy is complex, and is characterized by dysregulated lipid metabolism, insulin resistance, mitochondrial dysfunction and disturbances in adipokine secretion and signaling. These abnormalities lead to impaired calcium homeostasis, ultimately resulting in lusitropic and inotropic defects. This article discusses the impact of these hallmark factors in diabetic cardiomyopathy, and concludes with a survey of available and emerging therapeutic modalities.

Effective blockage of both the extrinsic and intrinsic pathways of apoptosis in mice by TAT-crmA

Evidence accumulates that in clinically relevant cell death, both the intrinsic and extrinsic apoptotic pathway synergistically contribute to organ failure. In search for an inhibitor of apoptosis that provides effective blockage of these pathways, we analyzed viral proteins that evolved to protect the infected host cells. In particular, the cowpox virus protein crmA has been demonstrated to be capable of blocking key caspases of both pro-apoptotic pathways. To deliver crmA into eukaryotic cells, we fused the TAT protein transduction domain of HIV to the N terminus of crmA. In vitro, the TAT-crmA fusion protein was efficiently translocated into target cells and inhibited apoptosis mediated through caspase-8, caspase-9, and caspase-3 after stimulation with alpha-Fas, etoposide, doxorubicin, or staurosporine. The extrinsic apoptotic pathway was investigated following alpha-Fas stimulation. In vivo 90% of TAT-crmA-treated animals survived an otherwise lethal dose of alpha-Fas and showed protection from Fas-induced organ failure. To examine the intrinsic apoptotic pathway, we investigated the survival of mice treated with an otherwise lethal dose of doxorubicin. Whereas all control mice died within 31 days, 40% of mice that concomitantly received intraperitoneal injections of TAT-crmA survived. To test the ability to comprehensively block both the intrinsic and extrinsic apoptotic pathway in a clinically relevant setting, we employed a murine cardiac ischemia-reperfusion model. TAT-crmA reduced infarction size by 40% and preserved left ventricular function. In summary, these results provide a proof of principle for the inhibition of apoptosis with TAT-crmA, which might provide a new treatment option for ischemia-reperfusion injuries.

Heart-brain interactions in mental stress-induced myocardial ischemia

Myocardial ischemia that results from emotional provocation occurs in as many as 30% to 50% of patients with coronary artery disease during the discourse of their lives. This emotionally provoked or mental stress ischemia is associated with poor prognosis, with emerging treatment strategies. This article outlines the conceptual constructs that support the pathophysiologic underpinnings, and biobehavioral aspects associated with this mental stress ischemia. We review a biobehavioral model in which cognitive stress is transduced in the brain. The response of the brain to psychosocial stress is a highly sophisticated and integrated process by which sensory inputs are evaluated and appraised for their importance in relation to previous experience and current goals. The biologic consequences of such stress transduced in the central nervous system has its effect on cardiovascular flow and function through changes in autonomic balance, which result in various biologic processes that culminate in the perturbation of flow and function of the heart.

Glycoproteome study in myocardial lesions serum by integrated mass spectrometry approach: preliminary insights

Bottom up proteomics requires efficient and selective pre-fractionation procedures to simplify the analysis of the enormous number of peptides resulting from the hydrolysis of a cellular extract enabling the detection, identification and the structural characterization of the post-translational modifications. Glycosylation, a well-known post-translational modification, plays a key role in the enormous complexity, and heterogeneity of the human blood serum proteome. Thereby, characterization of glycosylation from serum is a challenging task, even for the existing sophisticated analytical methodologies. Here we report a glycoproteomics study on the identification of even low abundant glycoproteins, including the localization of N-glycosylation sites and the glycan profiling in human sera from healthy and myocarditis affected donors. The strategy is simply based on proteolytic digestion of total serum proteins followed by a single enrichment step of glycopeptides on ConA lectin affinity chromatography. Glycopeptides were then deglycosylated by PNGaseF treatment and nano-liquid chromatography-electrospray ionization tandem mass spectrometry analyses of the free peptides provided the basis for both identification of the individual proteins and elucidation of their modification sites. Moreover, glycan profilings could be obtained by matrix-assisted laser desorption/ionization mass spectrometry analysis of the released oligosaccharides. Our data led to the identification of 68 different glycosylation sites within 49 different proteins. Moreover, the analyses carried out on glycans represent the first picture of a glycosylation pattern in myocardial lesions. As a whole, several differences in the glycosylation patterns from different sera were observed, thus indicating glycan profiling as a possible tool to discriminate among different diseases.

Characterization of multiple ion channels in cultured human cardiac fibroblasts

Background

Although fibroblast-to-myocyte electrical coupling is experimentally suggested, electrophysiology of cardiac fibroblasts is not as well established as contractile cardiac myocytes. The present study was therefore designed to characterize ion channels in cultured human cardiac fibroblasts.

Methods and Findings

A whole-cell patch voltage clamp technique and RT-PCR were employed to determine ion channels expression and their molecular identities. We found that multiple ion channels were heterogeneously expressed in human cardiac fibroblasts. These include a big conductance Ca²⁺-activated K⁺ current (BK_Ca) in most (88%) human cardiac fibroblasts, a delayed rectifier K⁺ current (IK_DR) and a transient outward K⁺ current (I_to) in a small population (15 and 14%, respectively) of cells, an inwardly-rectifying K⁺ current (I_Kir) in 24% of cells, and a chloride current (I_Cl) in 7% of cells under isotonic conditions. In addition, two types of voltage-gated Na⁺ currents (I_Na) with distinct properties were present in most (61%) human cardiac fibroblasts. One was a slowly inactivated current with a persistent component, sensitive to tetrodotoxin (TTX) inhibition (I_Na.TTX, IC₅₀ = 7.8 nM), the other was a rapidly inactivated current, relatively resistant to TTX (I_Na.TTXR, IC₅₀ = 1.8 µM). RT-PCR revealed the molecular identities (mRNAs) of these ion channels in human cardiac fibroblasts, including KCa.1.1 (responsible for BK_Ca), Kv1.5, Kv1.6 (responsible for IK_DR), Kv4.2, Kv4.3 (responsible for I_to), Kir2.1, Kir2.3 (for I_Kir), Clnc3 (for I_Cl), Na_V1.2, Na_V1.3, Na_V1.6, Na_V1.7 (for I_Na.TTX), and Na_V1.5 (for I_Na.TTXR).

Conclusions

These results provide the first information that multiple ion channels are present in cultured human cardiac fibroblasts, and suggest the potential contribution of these ion channels to fibroblast-myocytes electrical coupling.

Cytokines and matrix metalloproteinases as potential biomarkers in chronic heart failure

Heart failure (HF) is accompanied by the upregulation of bioactive signaling molecules, known as cytokines, and a family of downstream proteases, matrix metalloproteinases (MMPs). It is now apparent that these molecules contribute to adverse myocardial remodeling during HF. Elevated levels of cytokines and MMPs exist in the myocardium and can subsequently spill over into the systemic circulation. The purpose of this article is to examine clinical studies of HF that have quantified levels of different types of cytokines, MMPs and endogenous tissue inhibitors of MMPs in relation to this disease process. HF is a complex syndrome that can develop from various etiologies and can be characterized into two distinct phenotypes: systolic and diastolic. This article will present recent clinical studies that have identified significant differences between the cytokine and MMP circulating profile of systolic and diastolic HF patients. In general, elevated levels of cytokines and MMPs exist in systolic HF patients when compared with diastolic HF patients, whereas diastolic HF patients have elevated levels of cytokines and MMPs when compared with controls. Therefore, future studies distinguishing between HF phenotypes may provide more consistent results in determining possible analytes to be used as biomarkers. Furthermore, this article will emphasize why standardization of analytical techniques and establishment of referent cytokine and MMP levels are necessary if these analytes are to be used as biomarkers for the diagnosis, prognosis and evaluation of treatment in the context of HF.

Role of apoptosis in cardiovascular disease

Apoptosis plays a key role in the pathogenesis in a variety of cardiovascular diseases due to loss of terminally differentiated cardiac myocytes. Cardiac myocytes undergoing apoptosis have been identified in tissue samples from patients suffering from myocardial infarction, diabetic cardiomyopathy, and end-stage congestive heart failure. Apoptosis is a highly regulated program of cell death and can be mediated by death receptors in the plasma membrane, as well as the mitochondria and the endoplasmic reticulum. The cell death program is activated in cardiac myocytes by various stressors including cytokines, increased oxidative stress and DNA damage. Many studies have demonstrated that inhibition of apoptosis is cardioprotective and can prevent the development of heart failure. This review provides a current overview of the evidence of apoptosis in cardiovascular diseases and discusses the molecular pathways involved in cardiac myocyte apoptosis.

Dual roles of tumor necrosis factor-alpha receptor-1 in a mouse model of hindlimb ischemia

Signals in the tumor necrosis factor alpha (TNF-alpha) pathway are upregulated after ischemia, yet its role in peripheral ischemia remains unclear. We investigated the effect of TNF-alpha receptor 1 (TNFR-1) in acute limb ischemia of TNFR-1 knockout (TNFR-1-/-) and wild type (WT, TNFR-1+/+) mice. Laser Doppler scanning showed that although pre-ischemia blood flow levels were similar in these mice, the limb reperfusion after ischemia was significantly higher in TNFR-1-/- mice 1-7 days after injury. Consistently, fewer TUNEL-positive cells, less DNA fragmentation, and a lower ischemic score were detected in the TNFR-1-/- group when compared to WT controls. Western blot analysis revealed less expression of pro-apoptotic markers Bax and cleaved caspase-3 in TNFR-1-/- mice 1 day after ischemia, supporting the hypothesis that the absence of TNFR-1 results in a reduction of apoptosis. The rate of post-ischemia amputation was 50% in WT mice versus 0% in TNFR-1-/- mice. However, immunohistochemical co-staining of microvessel marker CD31 and cellular proliferation marker BrdU 21 days after ischemia showed an impaired angiogenic activity in the TNFR-1-/- mice. These data were supported by Western blot analysis, which indicated a decreased expression of angiopoietin-1 (Ang-1) and its receptor Tie-2 in TNFR-1-/- mice. Our results suggest that a deficiency in TNFR-1 prevents the activation of death-related proteins downstream to TNF-alpha and attenuates apoptosis in acute limb ischemia, but the lack of TNFR-1 signaling hinders the belated angiogenesis mediated by the Ang-1/Tie-2 pathway.

Cardioprotection by polysaccharide sulfate against ischemia/reperfusion injury in isolated rat hearts

AIM

Polysaccharide sulfate (PSS) is a new type of heparinoid synthesized with alginic acid as the basic material and then by chemical introduction of effective groups. Although PSS is successfully applied in ischemic cardio-cerebrovascular disease, its effect on cardiac function after ischemia/reperfusion (I/R) injury has previously not been investigated. The aim of the present study was to investigate whether PSS can protect the heart from I/R injury and the underlying mechanism of protection.

METHODS

Isolated rat hearts were perfused (Langendorff) and subjected to 20 min global ischemia followed by 60 min reperfusion with Kreb's Henseleit solution or PSS (0.3-100 mg/L). Myocardial contractile function was continuously recorded. Creatine kinase (CK) and lactate dehydrogenase (LDH) leakage were measured. Tumor necrosis factor-alpha (TNF-alpha) expression in cardiomyocytes was investigated. Western blot analysis for extracellular regulated kinases (ERKs), c-jun amino-terminal kinase (JNKs) and p38 mitogen-activated protein kinase (MAPK) activity was performed.

RESULTS

After I/R, cardiac contractility decreased, CK and LDH levels increased in the coronary effluent, and TNF-alpha expression increased in cardiomyocytes. PSS administration at concentrations of 1-30 mg/L improved cardiac contractility, reduced CK and LDH release and inhibited TNF-alpha production. Phosphorylated-p38MAPK (p-p38MAPK) and p-p54/p46-JNK increased in I/R rat hearts but diminished in PSS (1-30 mg/L) treated hearts. P-p44/p42-ERK levels were unchanged. In contrast, high concentrations of PSS (100 mg/L) had adverse effects that caused a worsening of heart function.

CONCLUSION

PSS has dose-dependent cardioprotective effects on the rat heart after I/R injury. The beneficial effects may be mediated through normalization of the activity of p38 MAPK and JNK pathways as well as controlling the level of TNF-alpha expression.

Human Kir2.1 channel carries a transient outward potassium current with inward rectification

We have previously reported a depolarization-activated 4-aminopyridine-resistant transient outward K(+) current with inward rectification (I (to.ir)) in canine and guinea pig cardiac myocytes. However, molecular identity of this current is not clear. The present study was designed to investigate whether Kir2.1 channel carries this current in stably transfected human embryonic kidney (HEK) 293 cells using whole-cell patch-clamp technique. It was found that HEK 293 cells stably expressing human Kir2.1 gene had a transient outward current elicited by voltage steps positive to the membrane potential (around -70 mV). The current exhibited a current-voltage relationship with intermediate inward rectification and showed time-dependent inactivation and rapid recovery from inactivation. The half potential (V (0.5)) of availability of the current was -49.4 +/- 2.1 mV at 5 mM K(+) in bath solution. Action potential waveform clamp revealed two components of outward currents; one was immediately elicited and then rapidly inactivated during depolarization, and another was slowly activated during repolarization of action potential. These properties were similar to those of I (to.ir) observed previously in native cardiac myocytes. Interestingly, inactivation of the I (to.ir) was strongly slowed by increasing intracellular free Mg(2+) (Mg(2+) ( i ), from 0.03 to 1.0, 4.0, and 8.0 mM). The component elicited by action potential depolarization increased with the elevation of Mg(2+) ( i ). Inclusion of spermine (100 muM) in the pipette solution remarkably inhibited both the I (to.ir) and steady-state current. These results demonstrate that the Mg(2+) ( i )-dependent current carried by Kir2.1 likely is the molecular identity of I (to.ir) observed previously in cardiac myocytes.

Mechanisms of sex differences in TNFR2-mediated cardioprotection

BACKGROUND

TNFR1/TNFR2 signaling may mediate different cellular and molecular responses (injury versus protection) and the balance may be affected by sex hormones. Previous studies have shown that females have improved myocardial functional recovery, TNFR1 signaling resistance, and increased SOCS3 expression after acute ischemia/reperfusion when compared with males. However, it is unknown whether the TNFR2 pathway protects the myocardium from ischemia/reperfusion injury, and if so, whether sex differences exist in TNFR2-mediated cardioprotection. Therefore, we hypothesized that (1) TNFR2 mediates myocardial protection from ischemia/reperfusion through STAT3, SOCS3, and vascular endothelial growth factor in both sexes; and (2) TNFR2 elicits greater protective signaling in females compared with males.

METHODS AND RESULTS

Isolated male and female mouse hearts from TNFR2 knockout, TNFR1/2 knockout, and wild-type (C57BL/6J or B6129SF2/J; n=5 to 6/group) were subjected to 20 minutes ischemia followed by 60 minutes reperfusion. TNFR2 deficiency decreased postischemic myocardial recovery in both sexes but had a greater effect on females. The deleterious effects of TNFR2 ablation were associated with a decrease in mRNA and protein levels of SOCS3, STAT3, and vascular endothelial growth factor as well as an increase in myocardial interleukin-1-beta production in female hearts. However, a significant increase in JNK activation and interleukin-1-beta protein levels was noted in male TNFR2KO hearts after ischemia/reperfusion. Additionally, TNFR1/2 knockout decreased myocardial function in female hearts but not males. This observation was associated with a decrease in mRNA levels of SOCS3, STAT3, and vascular endothelial growth factor and an increase in myocardial p38 mitogen-activated protein kinase activation in females.

CONCLUSIONS

Sex differences in the mechanisms of TNFR2-mediated cardioprotection occur by increasing STAT3, SOCS3, and vascular endothelial growth factor in females and by decreasing JNK in males.

Inducible nitric oxide synthase expression and cardiomyocyte dysfunction during sustained moderate ischemia in pigs

In acute myocardial ischemia, regional blood flow and function are proportionally reduced. With prolongation of ischemia, function further declines at unchanged blood flow. We studied the involvement of an inflammatory signal cascade in such progressive dysfunction and whether dysfunction is intrinsic to cardiomyocytes. In 10 pigs, ischemia was induced by adjusting inflow into the cannulated left anterior coronary artery to reduce coronary arterial pressure to 45 mm Hg (ISCH); 4 pigs received the inducible nitric oxide synthase (iNOS) inhibitors aminoguanidine or L-N(6)-(1-iminoethyl)-lysine during ISCH (ISCH+iNOS-Inhib); 6 pigs served as controls (SHAM). Anterior (AW) and posterior (PW) systolic wall thickening (sonomicrometry) were measured. After 6 hours, nitric oxide (NO) synthase (NOS) protein expression, NOS activity, and NO metabolites (nitrite/nitrate/nitroso species) were quantified in biopsies isolated from AW and PW. Cardiomyocyte shortening and intracellular calcium (Indo-1 acetoxymethyl ester) were measured without and with the NOS substrate L-arginine (100 micromol/L). In ISCH, AW wall thickening decreased from 42+/-4% (baseline) to 16+/-3% (6 hours). Wall thickening remained unchanged in ISCH-PW and SHAM-AW/PW. NOS2 (iNOS) protein expression and activity, but not NOS3 (endothelial NO synthase), were increased in ISCH-AW and ISCH-PW. iNOS expression correlated with increased nitrite contents. Cardiomyocyte shortening was reduced in ISCH-AW versus SHAM-AW (4.4+/-0.3% versus 5.6+/-0.3%). L-Arginine reduced cardiomyocyte shortening further in ISCH-AW (to 2.8+/-0.2%) and ISCH-PW (3.4+/-0.4% versus 5.4+/-0.4%) but not in SHAM or in ISCH+iNOS-Inhib; intracellular [Ca(2+)] remained unchanged. With L-arginine, in vitro AW cardiomyocyte shortening correlated with in vivo AW wall thickening (r=0.72). In conclusion, sustained regional ischemia induces myocardial iNOS expression in pigs, which contributes to contractile dysfunction at the cardiomyocyte level.

Biology of TNFalpha and IL-10, and their imbalance in heart failure

Our understanding of the multiple in vivo functions of the proinflammatory cytokine, tumor necrosis factor (TNFalpha), is advancing at a rapid pace. In addition to its antitumor effects, overproduction of TNFalpha provokes tissue injury and organ failure. TNFalpha has also been shown to be cardiodepressant and responsible for various cardiovascular complications. It appears that still much needs to be learned for a full comprehension of the role of TNFalpha in heart biology. Another cytokine, interleukin-10 (IL-10), has been shown to have anti-inflammatory properties. It is suggested to counterbalance many adverse effects of TNFalpha. IL-10 suppresses the production of TNFalpha and many other proinflammatory cytokines. TNFalpha-induced oxidative stress is also known to be mitigated by IL-10. Moreover, improvement in cardiac function after treatment with various drugs is also shown to be associated with an increase in IL-10 content. Based on the data reviewed in here, it is suggested that an optimal balance between IL-10 and TNFalpha may be a new therapeutic strategy for a healthier heart.

Estrogen-mediated protection in myocardial ischemia-reperfusion injury

Before menopause, a woman has a relatively low risk for developing cardiovascular disease. After menopause, however, the risk increases nearly twofold and cardiovascular disease remains the number one cause of death among women. Observational trials and studies in animal models of cardiovascular disease suggested that females have reduced injury after myocardial ischemia and reperfusion injury. However, two large clinical trials, the women's health initiative (WHI) and the heart estrogen and progestin replacement study (HERS), found an increase in cardiovascular incidences in women taking hormone replacement therapy. The discrepancy between these data highlights the need for further research on the mechanism of estrogen in the cardiovascular system. Animal studies have demonstrated protective effects by endogenous estrogen (gender differences) and also by the administration of exogenous estrogen. In vivo studies suggest a possible anti-inflammatory mechanism of estrogen. Exogenous estrogen has been shown to have anti-oxidant activities. Pre-treatment with estrogen prior to myocardial ischemia and reperfusion causes a decrease in neutrophil infiltration into the irreversibly injured myocardium, decrease in C-reactive protein expression, and deposition of the membrane attack complex. This review will summarize the protection afforded by estrogen as well as discuss several possible mechanisms of protection for exogenous estrogen administration.

Effect of some natural products either alone or in combination on gastritis induced in experimental rats

Gastritis, an inflammatory state in gastric mucosa, can be induced experimentally in various ways. The present study considered the iodoacetamide model (Iodo). Omega-3 fatty acids (fish oil), black seed oil, and curcuminoids (natural products) in addition to omeprazole (synthetic proton-pump inhibitor) were tested. Supplementation of 0.1% iodoacetamide to drinking water of experimental rats for two consecutive weeks resulted in: (i) increased serum nitric oxide (NO) and gastrin, and decreased pepsinogen, (ii) depletion of gastric mucosal glutathione (GSH), and (iii) increased gastric mucosal lipid peroxidation (MDA), but failed to affect gastric mucosal myeloperoxidase (MPO) activity. Histological examination showed marked neutrophilic infiltration after 1 week of iodoacetamide administration and shedding of apical cell layer with pale edematous vacuolated gastric gland cells and thickening of muscularis mucosa after 2 weeks of iodoacetamide intake. Individual administration of omega-3 fatty acids 12 mg/kg, black seed oil 50 mg/kg, and curcuminoids 50 mg/kg body weight orally daily for 3 weeks decreased MDA, gastrin, and NO, and normalized mucosal GSH but failed to affect serum pepsinogen level. Combined administration of these natural products for 3 weeks normalized MPO activity, and other effects were nearly the same as with individual use. Omeprazole administration 30 mg/kg body weight orally daily for 3 weeks induced a similar response except for an observed increase in serum gastrin and pepsinogen levels.

Increased activities of cardiac matrix metalloproteinases matrix metalloproteinase (MMP)-2 and MMP-9 are associated with mortality during the acute phase of experimental Trypanosoma cruzi infection

The strong inflammatory reaction that occurs in the heart during the acute phase of Trypanosoma cruzi infection is modulated by cytokines and chemokines produced by leukocytes and cardiomyocytes. Matrix metalloproteinases (MMPs) have recently emerged as modulators of cardiovascular inflammation. In the present study we investigated the role of MMP-2 and MMP-9 in T. cruzi-induced myocarditis, by use of immunohistochemical analysis, gelatin zymography, enzyme-linked immunosorbent assay, and real-time polymerase chain reaction to analyze the cardiac tissues of T. cruzi-infected C57BL/6 mice. Increased transcripts levels, immunoreactivity, and enzymatic activity for MMP-2 and MMP-9 were observed by day 14 after infection. Mice treated with an MMP inhibitor showed significantly decreased heart inflammation, delayed peak in parasitemia, and improved survival rates, compared with the control group. Reduced levels of cardiac tumor necrosis factor-alpha, interferon-gamma, serum nitrite, and serum nitrate were also observed in the treated group. These results suggest an important role for MMPs in the induction of T. cruzi-induced acute myocarditis.

Desflurane preconditioning inhibits endothelial nuclear factor-kappa-B activation by targeting the proximal end of tumor necrosis factor-alpha signaling

BACKGROUND

Volatile anesthetics interfere with inflammatory cytokine production and expression of adhesion molecules which are critical for ischemia reperfusion induced injury. Nuclear factor (NF)-kappaB has been reported to be suppressed in this process, but the detailed molecular mechanism is still unclear.

METHODS

In this study, ECV304 (a human umbilical vein endothelial cell line) was preconditioned with 30 min desflurane (1 minimal alveolar concentration), after 15 min washout, 30 min anoxia, and 60 min reoxygenation was performed. ECV304 was finally stimulated with tumor necrosis factor (TNF)-alpha (10 ng/mL). Control groups, which were not preconditioned and/or not stimulated, were also included in the protocol. IkappaB-alpha, phospho-IkappaB-alpha, phospho-IkappaB kinase (IKKalpha)/IKKbeta, and phospho-p38 were detected by Western blotting. The nuclear NF-kappaB p65 subunit was measured by subcellular fractionation and Western blotting. The surface expression of TNF-R1 was measured by flow cytometry. Receptor-associated signaling adaptors, e.g., TNF receptor-associated factor 2 (TRAF2) and IKK-alpha, were evaluated by immunoprecipitation by TNF-R1 antibody and subsequent Western blotting.

RESULTS

Desflurane preconditioning inhibits IkappaB-alpha phosphorylation, degradation, and p65 nuclear localization. Desflurane also affects p38 phosphorylation, which is needed for optimal inflammatory response. The phosphorylation of IKKalpha/IKKbeta was suppressed by preconditioning while the surface abundance of TNF-R1 was not affected. The association of TRAF2 and IKK-alpha with TNF-R1 was compromised by desflurane.

CONCLUSIONS

Our results suggest that the molecular target of desflurane in the NF-kappaB pathway is upstream of IKK activation. The abundance of TNF-R1 on the cell membrane is not affected by anesthetic preconditioning. We suggest that desflurane preconditioning targets the proximal end of TNF-alpha signaling.

TNFalpha-initiated oxidative/nitrative stress mediates cardiomyocyte apoptosis in traumatic animals

Whole body non-penetrating trauma causes myocardial infarction in humans and mechanical trauma (MT) results in cardiac dysfunction in animals. Our recent study demonstrated that incubation of cardiomyocytes with plasma isolated from MT animals causes significant cardiomyocyte apoptosis that can be blocked by neutralization of TNFalpha. The present study attempted to obtain direct in vivo evidence to support that overproduction of TNFalpha plays a causative role in trauma-induced cardiomyocyte apoptosis. Non-lethal MT caused significant TNFalpha overproduction (2.4-fold at 1.5 h after MT) and increased cardiomyocyte apoptosis (starting 3 h and peaking 12 h after MT). Pharmacological inhibition of TNFalpha with etanercept or TNFalpha gene deletion reduced post-trauma myocyte apoptosis (P<0.01). Expression of iNOS and NADPH oxidase, overproduction of NO and O2-, and excessive protein nitration in the MT heart were all significantly reduced in etanercept-treated or TNFalpha-/- mice, suggesting that oxidative/nitrative stress may contribute to TNFalpha-initiated myocyte apoptosis in MT hearts. Additional experiments demonstrated that inhibiting iNOS (1400W) or NADPH oxidase (apocynin), or scavenging peroxynitrite (FP15) significantly reduced myocyte apoptosis in MT animals (P<0.01). Collectively, these data demonstrated that non-lethal mechanical trauma caused significant TNFalpha production that in turn stimulated myocardial apoptosis via oxidative/nitrative stress.

Ischemic preconditioning: from molecular mechanisms to therapeutic opportunities

Ischemia/reperfusion (I/R) injury is a major contributory factor to cardiac dysfunction and infarct size that determines patient prognosis after acute myocardial infarction. Considerable interest exists in harnessing the heart's endogenous capacity to resist I/R injury, known as ischemic preconditioning (IPC). The IPC research has contributed to uncovering the pathophysiology of I/R injury on a molecular and cellular basis and to invent potential therapeutic means to combat such damage. However, the translation of basic research findings learned from IPC into clinical practice has often been inadequate because the majority of basic research findings have stemmed from young and healthy animals. Few if any successful implementations of IPC have occurred in the diseased hearts that are the primary target of viable therapies activating cardioprotective mechanisms to limit cardiac dysfunction and infarct size. Therefore, the first purpose of this review is to facilitate understanding of pathophysiology of I/R injury and the mechanisms of cardioprotection afforded by IPC in the normal heart. Then I focus on the problems and opportunities for successful bench-to-bedside translation of IPC in the diseased hearts.

TNF-alpha and IL-10 gene polymorphisms versus cardioimmunological responses in sudden infant death

We hypothesized that genetic variations of cytokines could contribute to the risk of developing a fatal immunological reaction in the heart of infants. Thus, tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 gene polymorphisms versus induction of cardioimmunologxical responses in victims of sudden infant death syndrome (SIDS) were explored. We genotyped 35 infants (23 cases of SIDS and 12 infants with a known cause of death), and 100 healthy adult controls for IL-10 -1082 G/A, -592 C/A and TNF-alpha-238 G/A, -308 G/A. We found a higher frequency of the ATA haplotype and ATA/ATA genotype of IL-10 associated with SIDS (13%). The frequency of homozygote infants for IL-10 haplotypes in SIDS was higher (52%) than the control group (34%). All SIDS cases were homozygotice for the TNF-alpha-238 G allele and 20 infants were homozygous for the TNF-alpha-308 G allele in the same group. None of the infants with higher levels of infiltrated T-cells (n=8) was homozygous for IL-10 gene polymorphisms, whereas in contrast 3 cases of the 6 that displayed higher levels of cardiac mast cells were homozygous. In this study, the increased number of interstitial T-cells, mast cells, and macrophages in the myocardial interstitium demonstrated no correlation with the genotype for either cytokines.

TNFR1 and TNFR2 Signaling Interplay in Cardiac Myocytes

Tumor necrosis factor alpha (TNFalpha) plays a major role in chronic heart failure, signaling through two different receptor subtypes, TNFR1 and TNFR2. Our aim was to further delineate the functional role and signaling pathways related to TNFR1 and TNFR2 in cardiac myocytes. In cardiac myocytes isolated from control rats, TNFalpha induced ROS production, exerted a dual positive and negative action on [Ca(2+)] transient and cell fractional shortening, and altered cell survival. Neutralizing anti-TNFR2 antibodies exacerbated TNFalpha responses on ROS production and cell death, arguing for a major protective role of the TNFR2 pathway. Treatment with either neutralizing anti-TNFR1 antibodies or the glutathione precursor, N-acetylcysteine (NAC), favored the emergence of TNFR2 signaling that mediated a positive effect of TNFalpha on [Ca(2+)] transient and cell fractional shortening. The positive effect of TNFalpha relied on TNFR2-dependent activation of the cPLA(2) activity, independently of serine 505 phosphorylation of the enzyme. Together with cPLA(2) redistribution and AA release, TNFalpha induced a time-dependent phosphorylation of ERK, MSK1, PKCzeta, CaMKII, and phospholamban on the threonine 17 residue. Taken together, our results characterized a TNFR2-dependent signaling and illustrated the close interplay between TNFR1 and TNFR2 pathways in cardiac myocytes. Although apparently predominant, TNFR1-dependent responses were under the yoke of TNFR2, acting as a critical limiting factor. In vivo NAC treatment proved to be a unique tool to selectively neutralize TNFR1-mediated effects of TNFalpha while releasing TNFR2 pathways.

Postconditioning: a mechanical maneuver that triggers biological and molecular cardioprotective responses to reperfusion

Infarct size is determined not only by the duration and severity of ischemia, but also by pathological processes initiated at reperfusion (reperfusion injury). Numerous pharmacological strategies have been reported which administer drugs at or just before the onset of reperfusion, with subsequent salubrious effects, notably a reduction in infarct size. However, few if any of these strategies have become standard of care in the catheterization laboratory setting. Postconditioning, defined as repeated brief cycles of reperfusion interrupted by ischemia (or hypoxia) applied at the onset of reperfusion, was recently introduced as a mechanical strategy to attenuate reperfusion injury. Postconditioning intervenes only during the first few minutes of reperfusion. However, it reduces endothelial activation and dysfunction, the inflammatory response to reperfusion, necrosis, and apoptosis both acutely and long-term. Cardioprotection has been demonstrated by multiple independent laboratories and in multiple species. Postconditioning stimulates G-protein coupled receptors by their cognate endogenously released ligands and surprisingly activates survival kinases that may converge on mitochondrial K(ATP) channels and the permeability transition pore. Postconditioning has been shown in two clinical studies to reduce infarct size in patients undergoing percutaneous coronary intervention in the catheterization laboratory, and at least five other studies are in some phase of implementation. This significant reduction in infarct size has implications for reduction in heart failure as a consequence of myocardial infarction, but this link has yet to be demonstrated. The salubrious effects of postconditioning are an indirect validation of the experimental and clinical importance of reperfusion injury in the setting of coronary artery occlusion.

The effect of adrenomedullin on the L-type calcium current in myocytes from septic shock rats: signaling pathway

Adrenomedullin (ADM) is upregulated in cardiac tissue under various pathophysiological conditions, particularly in septic shock. The intracellular mechanisms involved in the effect of ADM on adult rat ventricular myocytes are still to be elucidated. Ventricular myocytes were isolated from adult rats 4 h after an intraperitoneal injection of lipopolysaccharide (LPS, 10 mg/kg). Membrane potential and L-type calcium current ( ICa,L) were determined using whole cell patch-clamp methods. APD in LPS group was significantly shorter than control values (time to 50% repolarization: LPS, 169 ± 2 ms; control, 257 ± 2 ms, P < 0.05; time to 90% repolarization: LPS, 220 ± 2 ms; control, 305 ± 2 ms, P < 0.05). ICa,Ldensity was significantly reduced in myocytes from the LPS group (−3.2 ± 0.8 pA/pF) compared with that of control myocytes (−6.7 ± 0.3 pA/pF, P < 0.05). The ADM antagonist ADM-(22-52) reversed the shortened APD and abolished the reduction of ICa,Lin shock myocytes. In myocytes from control rats, incubating with ADM for 1 h induced a marked decrease in peak ICa,Ldensity. This effect was reversed by ADM-(22-52). The Giprotein inhibitor, pertussis toxin (PTX), the protein kinase A (PKA) inhibitor, KT-5720, and the specific cyclooxygenase 2 (COX-2) inhibitor, nimesulide, reversed the LPS-induced reduction in peak ICa,L. The results suggest a COX-2-involved PKA-dependent switch from Gscoupled to PTX-sensitive Gicoupling by ADM in adult rat ventricular myocytes. The present study delineates the intracellular pathways involved in ADM-mediated effects on ICa,Lin adult rat ventricular myocytes and also suggests a role of ADM in sepsis.

Reduction of gap and adherens junction proteins and intercalated disc structural remodeling in the hearts of mice submitted to severe cecal ligation and puncture sepsis*

OBJECTIVE

The present study describes intercalated disc remodeling under both protein expression and structural features in experimental severe sepsis induced by cecal ligation and puncture in mice.

DESIGN

Controlled animal study.

SETTING

University research laboratory.

SUBJECTS

Male C57BL/6 mice.

INTERVENTIONS

Mice were submitted to moderate and severe septic injury by cecal ligation and puncture.

MEASUREMENT AND MAIN RESULTS

Severe septic injury was accompanied by a large number of bacteria in the peritoneal cavity and blood, high levels of tumor necrosis factor-alpha, and monocyte inflammatory protein-1alpha in the septic focus and serum, marked hypotension, and a high mortality rate. Western blot analysis and immunofluorescence showed a marked decrease of key gap and adherens junction proteins (connexin43 and N-cadherin, respectively) in mice submitted to severe septic injury. These changes may result in the loss of intercalated disc structural integrity, characterized in the electron microscopic study by partial separation or dehiscence of gap junctions and adherens junctions.

CONCLUSIONS

Our data provide important insight regarding the alterations in intercalated disc components resulting from severe septic injury. The intercalated disc remodeling under both protein expression and structural features in experimental severe sepsis induced by cecal ligation and puncture may be partly responsible for myocardial depression in sepsis/septic shock. Although further electrophysiological studies in animals and humans are needed to determine the effect of these alterations on myocardial conduction velocity, the abnormal variables may emerge as therapeutic targets, and their modulation might provide beneficial effects on future cardiovascular outcomes and mortality in sepsis.

Autoimmunological features in inflammatory cardiomyopathy

During recent years, increasing evidence has been obtained that cellular as well as humoral autoimmunity is involved in the pathogenesis of dilated cardiomyopathy (DCM). The immune system is generally activated by viral infections with the objective of virus elimination from the myocardium. However, a relevant number of patients demonstrate viral persistence and/or chronic inflammation in the myocardium. This chronic myocardial inflammation, defined by chronic inflammation, is termed "inflammatory cardiomyopathy" according to the WHO classification of cardiomyopathies. Chronic inflammation is frequently followed by the development of autoimmunity. A breakdown in the control mechanisms protecting against autoimmune reactions by both presentation of normally not accessible self-antigens and bystander- activation, induced by the pathogen, leads to the formation of autoreactive antibodies and T cells. The auto-reactive antibodies interact directly with heart tissue resulting in altered signal transduction or complement activation, whereas the T cell-mediated mechanisms include direct attack by cytotoxic T cells or indirect effects of cytotoxic cytokines released by stimulated T cells or macrophages.

Toll-like receptor 2 activation by bacterial peptidoglycan-associated lipoprotein activates cardiomyocyte inflammation and contractile dysfunction

OBJECTIVE

Although cardiac dysfunction plays an important role in the pathogenesis of sepsis, the mechanisms that underlie cardiac dysfunction in sepsis remain poorly understood. Bacterial peptidoglycan-associated lipoprotein (PAL), an outer-membrane protein of Gram-negative bacteria, was recently found to be released into the bloodstream in sepsis and to cause inflammation and death in mice. The present studies assessed the effects of PAL on cardiomyocyte function and its signal transduction in cardiomyocytes.

DESIGN

Randomized prospective animal study.

SETTING

Research laboratory.

SUBJECTS

Male C57BL/6 mice, B6;129S-Tnfrsf1a(tm1Imx) Tnfrsf1b(tm1Imx)/J knockout mice, Toll-like receptor 2 (TLR2) knockout mice, and myeloid differentiation factor 88 (MyD88) knockout mice.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Immunohistochemical staining and immunoblot analysis indicated that intravenously injected PAL bound to myocardium. Injection of PAL decreased cardiac function in vivo. Challenge with PAL altered cell shortening and Ca2+ transients in isolated mouse cardiomyocytes but not in cardiomyocytes isolated from TLR2 -/- and MyD88 -/- mice. Cytokine profiling arrays demonstrated that tumor necrosis factor-alpha (TNFalpha), granulocyte colony-stimulating factor, and interferon-gamma-production were elevated in PAL-treated cardiomyocytes. Increased TNFalpha production was abolished in MyD88 -/- cardiomyocytes but restored by adenovirally mediated expression of MyD88. PAL did not affect cell shortening and Ca2+ cycling in cardiomyocytes obtained from mice deficient for TNFalpha receptor (TNFR) 1 and TNFR2 (TNFR1/2 -/-).

CONCLUSION

Our data reveal that PAL uses the TLR2/MyD88 signaling cascade to induce cardiomyocyte dysfunction and inflammatory responses and that TNFalpha is a major mediator of PAL-induced dysfunction in cardiomyocytes. These studies suggest that circulating PAL and other TLR2 agonists may contribute to cardiac dysfunction in sepsis.

FUNCTIONAL IMPAIRMENT OF CARDIAC TRANSIENT OUTWARD K+CURRENT AS A RESULT OF ABNORMALLY ALTERED CELLULAR ENVIRONMENT

1. Physiological functions of cardiac cells require a normal cellular environment. Under pathological conditions, there is a loss of normal cellular environment due to metabolic perturbations and other abnormalities. To test the hypothesis that cellular environmental stresses can create an electrophysiological substrate for electrical disorders in the heart, we investigated the effects of hypoxia, acidosis and ischaemia on transient outward K+ current (I(to)) in single canine ventricular myocytes. 2. The I(to) was studied because it plays a critical role in initiating cardiac repolarization and, thereby, arrhythmias. It was found that I(to) was significantly depressed by some 30% under hypoxic conditions relative to that in a normal cellular environment with normal Tyrode's solution. 3. Acidosis created by lowering the pH of the external solution from 7.4 to 7.2 produced a substantial (approximately 35%) reduction of the I(to) amplitude. 4. A marked impairment of I(to) function was consistently observed in ischaemic hearts in the canine coronary artery ligation model, with an approximate 30% decrease in the size of I(to). 5. Importantly, the impairment of I(to) under these environmental stresses was largely reversible following restoration to normal conditions. 6. The results of the present study suggest that I(to) is susceptible to changes in the cellular environment and the functional impairment of I(to) under environmental stresses contributes to arrhythmias under relevant pathological conditions of the heart.

Anti-tumour necrosis factor-alpha therapy in heart failure: future directions

The elevated level of tumour necrosis factor-alpha (TNF-alpha) in patients with heart failure has triggered interest in investigating the role of TNF-alpha in the pathogenesis of heart failure. Both clinical and experimental evidence has suggested that high levels of TNF-alpha occur in heart failure and lead to progression of left ventricular dysfunction. In addition, it has been documented that inhibition of TNF-alpha reverses its deleterious effects in heart failure. A number of clinical trials have been initiated to investigate the effect of anti-TNF-alpha therapy in patients with heart failure. The discouraging results of recent clinical trials of anti-TNF-alpha therapy in patients with heart failure have raised a number of questions about the role of TNF-alpha in heart failure. The present review critically analyzes the reasons of failure of anti-TNF-alpha therapy in heart failure. Moreover the potential approaches for the development of new anti-TNF-alpha therapy has been discussed which may open new vista of the management of heart failure.

Associative pairing enhances action potential back-propagation in radial oblique branches of CA1 pyramidal neurons

Back-propagating action potentials (bAPs) are involved in associative synaptic plasticity and the modulation of dendritic excitability. We have used high-speed confocal and two-photon imaging to measure calcium and voltage signals associated with action potential propagation into oblique branches of CA1 pyramidal neurons in adult hippocampal slices. The spatial profile of the bAP-associated Ca(2+) influx was biphasic, with an initial increase in the proximity of the branch point followed by a progressive decrease. Voltage imaging in the branches showed that bAP amplitude was initially constant and then steadily declined with distance from the soma. To determine the role of transient K(+) channels in this profile, we used external Ba(2+) (150 microm) as a channel blocker, after characterizing its effect on A-type K(+) channels in the apical trunk. Bath application of Ba(2+) significantly reduced the A-type K(+) current in outside-out patches and nearly eliminated the distance-dependent decrease in bAP amplitude and its associated Ca(2+) signal. Finally, small amplitude bAPs at more distal oblique branch locations could be boosted by simultaneous branch depolarization, such that the paired Ca(2+) signal became nearly the same for proximal and distal oblique dendrites. These data suggest that dendritic K(+) channels regulate the amplitude of bAPs to create a dendritic Ca(2+) signal whose magnitude is inversely related to the electrotonic distance from the soma when bAPs are not associated with a significant amount of localized synaptic input. This distance-dependent Ca(2+) signal from bAPs, however, can be amplified and a strong associative signal is produced once the proper correlation between synaptic activation and AP output is achieved. We hypothesize that these two signals may be involved in the regulation of the expression and activity of dendritic voltage- and ligand-gated ion channels.

Postconditioning attenuates cardiomyocyte apoptosis via inhibition of JNK and p38 mitogen-activated protein kinase signaling pathways

A sequence of intermittent interruptions of oxygen supply (i.e., postconditioning, Postcon) at reoxygenation reduces oxidant-induced cardiomyocyte loss. This study tested the hypothesis that prevention of cardiomyocyte apoptosis by Postcon is mediated by mitogen-activated protein kinases pathways. Primary cultured neonatal rat cardiomyocytes were exposed to 3 h hypoxia followed by 6 h of reoxygenation. Cardiomyocytes were postconditioned by three cycles each of 5 min reoxygenation and 5 min hypoxia after prolonged hypoxia. Relative to hypoxia alone, reoxygenation stimulated expression of JNKs and p38 kinases, corresponding to increased activity of JNKs (phospho-c-Jun) and p38 (phospho-ATF2). The level of TNFalpha in cell lysates, activity of cytosolic caspases-8, -3, expression of Bax and the number of apoptotic cardiomyocytes were increased while expression of Bcl-2 was decreased with reoxygenation. Consistent with an attenuation in generation of superoxide anions detected by lucigenin-enhanced chemiluminescence at early period of reoxygenation, treatment of cardiomyocytes with Postcon further reduced expression and activity of JNKs and p38 kinases, level of TNFalpha, the frequency of apoptotic cells and expression of Bax. However, the inhibitory effects of Postcon on these changes were lost when its application was delayed by 5 min after the start of reoxygenation. Addition of a JNK/p38 stimulator, anisomycin into cardiomyocytes at the beginning of reoxygenation eliminated protection by Postcon. These data suggest that 1) hypoxia/reoxygenation elicits cardiomyocyte apoptosis in conjunction with expression and activation of JNK and p38 kinases, release of TNFalpha, activation of caspases, and an increase in imbalance of pro-/anti-apoptotic proteins; 2) Postcon attenuates cardiomyocyte apoptosis, potentially mediated by inhibiting JNKs/p-38 signaling pathways and reducing TNFalpha release and caspase expression.

Cardioprotective effect of aprotinin on myocardial ischemia/reperfusion injury during cardiopulmonary bypass

BACKGROUND

Aprotinin is a serine protease inhibitor used extensively in cardiac operations to reduce postoperative bleeding. It also has cardioprotective effects in ischemia/reperfusion injury. In this study, the effects of aprotinin on the release of cardiac markers were evaluated in patients who had good ventricular function and were undergoing coronary artery bypass grafting with cardiopulmonary bypass (CPB).

METHODS AND RESULTS

Eighty male patients with an ejection fraction >or=40%, were randomized into either an aprotinin (Group-I; n=40) or control (Group-II; n=40) group. Patients in the aprotinin group received the full Hammersmith doses of aprotinin (2 x 10(6) KIU pre-CPB, 2 x 10(6) KIU at pump prime, 500,000 KIU/h during CPB), whereas the patients in the control group received only saline solutions. Cardiac troponin-I (cTnI) levels were measured before surgery, immediately after surgery, and at postoperative 6(th), 12(th), 24(th) h and 5(th) day. Creatine kinase (CK)-MB measurements were performed at the same time except for the postoperative 5(th) day. Cardiac index (CI), mixed venous oxygen saturation and lactate dehydrogenase (LDH) measurements were also performed.

CONCLUSION

Although all patients were in reasonable condition, less myocardial enzyme leakage occurred on the aprotinin group, suggesting that aprotinin has a protective effect on the myocardium beyond that achieved with blood cardioplegia and systemic hypothermia. Because of aprotinin's effects on multiple targets of metabolism, its protective value might increase in more complicated cases.

Coxsackievirus B3 induces T regulatory cells, which inhibit cardiomyopathy in tumor necrosis factor-alpha transgenic mice

Innate immunity promotes both the generation of autoimmunity and immunoregulation of adaptive immunity. Transgenic mice expressing the tumor necrosis factor-alpha (TNF-alpha) gene under the cardiac myosin promoter (TNF1.6 mice) develop dilated cardiomyopathy. Transgenic mice show extensive cardiac inflammation, suggesting that immunopathogenic mechanisms may promote cardiomyopathy. Two coxsackievirus B3 (CVB3) variants infect and replicate in the heart. H3 variant is highly myocarditic, but H310A1 variant activates CD4(+) T regulatory cells, which protect against viral myocarditis. T-cell depletion of TNF1.6 mice using monoclonal anti-CD3 or anti-CD4 antibody significantly reduced heart size and plasma troponin I concentrations compared with control TNF1.6 mice. Cardiomyopathy in TNF1.6 mice correlates to a CD4(+)Th1 response and autoimmune IgG2a antibodies. TNF1.6 mice infected with H310A1 virus reduced heart size and cardiac inflammation corresponding to the activation of CD4(+)CD25(+)FoxP3(+) (T regulatory cells). Immunosuppression is dependent on IL-10 but not TGFbeta. Adoptive transfer of the CD4(+)CD25(+) cells from H310A1-infected mice into uninfected TNF1.6 recipients abrogated cardiomyopathy. Exogenous administration of recombinant TNF-alpha to H310A1-infected mice for 4 days abrogated immunosuppression. Cardiac enlargement in TNF1.6 mice is partly attributable to T-cell activation and humoral autoimmunity caused by cytokine expression. T regulatory cells induced by H310A1 virus abrogate autoimmunity caused by TNF-alpha overexpression. H3 virus infection induces high levels of systemic TNF-alpha, whereas H310A1 virus does not. The low TNF-alpha response during H310A1 infections is likely responsible for the T regulatory cell response in these animals.

Inhibition of p38 mitogen-activated protein kinase attenuates left ventricular dysfunction by mediating pro-inflammatory cardiac cytokine levels in a mouse model of diabetes mellitus

AIMS/HYPOTHESIS

We investigated the effect of SB 203580, a pharmacological inhibitor of p38 mitogen-activated protein kinase (MAPK), on cardiac inflammation, cardiac fibrosis, and left ventricular function using an animal model of diabetic cardiomyopathy.

MATERIALS AND METHODS

Diabetes mellitus was induced by streptozotocin (50 mg/kg i.p. for 5 days) in 20 C57/BL6J mice. Diabetic mice were treated daily with the p38 MAPK inhibitor SB 203580 (1 mg/kg daily, n=10) or with placebo (n=10) and were compared to non-diabetic controls. Left ventricular function was measured by pressure-volume loops after 8 weeks of diabetes mellitus. The parameters for systolic function were the end systolic pressure-volume relationship (ESPVR) and the left ventricular end systolic pressure. The parameters for diastolic function were the left ventricular end diastolic pressure and the end diastolic pressure-volume relationship (EDPVR). Cardiac tissue was analysed by ELISA for the protein content of the cytokines TNF-alpha, IL6, IL1-beta, and TGF-beta1. Phosphorylation of MAPK p38 was analysed by western blot, and the total cardiac collagen content was analysed by Sirius red staining.

RESULTS

Left ventricular dysfunction was documented by impaired ESPVR and EDPVR. Cardiac cytokine levels and cardiac fibrosis were increased in diabetic animals compared to controls. Treatment with the p38 inhibitor normalised cardiac cytokine levels and improved systolic function, but did not change cardiac fibrosis and diastolic dysfunction compared to placebo.

CONCLUSIONS/INTERPRETATION

Pharmacological inhibition of p38 MAPK prevents cardiac inflammation and attenuates left ventricular dysfunction in diabetic cardiomyopathy.

Tumor necrosis factor receptor 1 signaling resistance in the female myocardium during ischemia

BACKGROUND

Tumor necrosis factor-alpha (TNF) is increased in myocardial tissue after ischemia and reperfusion (I/R). TNF contributes to postischemic myocardial dysfunction and induces proinflammatory signaling, which may be mediated by the 55-kDa TNF receptor (TNFR1). In humans, there is a direct correlation between functional capacity, survival, and circulating TNF levels. Although decreasing the TNF level in animals was beneficial after myocardial ischemia, simply decreasing the bioavailability of TNF in humans with heart failure was not beneficial. This led to the important appreciation that TNF may have beneficial or deleterious effects in the heart, depending on which of its receptors is activated. Females have a lower incidence of heart failure and a higher heart failure survival than males. We hypothesized that TNFR1 signaling resistance occurs in the female myocardium during ischemia.

METHODS AND RESULTS

Hearts from male and female TNFR1-knockout and wild-type (WT) mice were subjected to I/R. Female WT mice had better postischemic recovery than did male WT mice, an effect that appeared to be due to TNFR1 signaling resistance in females. Female WT mice had less myocardial depression after TNF infusion despite equivalent TNFR1 expression. Interestingly, TNFR1 ablation improved postischemic myocardial function, decreased activation of p38 mitogen-activated protein kinase, and reduced expression of interleukins-1beta and -6 in males but not in females. Furthermore, WT females expressed more of the suppressor of cytokine signaling protein 3 after I/R, which may in part explain TNFR1 signaling resistance in the female myocardium.

CONCLUSIONS

This study demonstrates that sex differences exist in myocardial TNF signaling by TNFR1 after I/R.

Reduction of apoptosis in the amygdala by an A2A adenosine receptor agonist following myocardial infarction

It has been observed that a cytokine synthesis inhibitor, pentoxifylline, prevents the apoptotic processes taking place in the amygdala following myocardial infarction. However, it is unknown if the cardioprotective effect of A(2A) adenosine receptor agonist, CGS21680, which reduces cytokine synthesis, would lead to such amygdala apoptosis regression. Thus, this study was designed to investigate whether cardioprotective A(2A) adenosine receptor activation reduces apoptosis in the amygdala following myocardial infarction. Anesthetized rats were subjected to left anterior descending coronary artery occlusion for 40 min, followed by 72 h of reperfusion. The A(2A) agonist CGS21680 (0.2 mug/kg/min i.v.) was administered continuously for 120 min, starting (1) five minutes prior to instituting reperfusion (Early) or (2) five minutes after the beginning of reperfusion (Late). After reperfusion, myocardial infarct size was determined and the amygdala was dissected from the brain. Infarct size was reduced significantly in the Early compared to the Control group (34.6 +/- 1.8% and 52.3 +/- 2.8% respectively; p < 0.05), with no difference compared to the Late group (40.1 +/- 6.1%). Apoptosis regression was documented in the amygdala of the Early group by an enhanced phosphatidylinositol 3-kinase-Akt pathway activation and Bcl-2 expression concurrently to a caspase-3 activation limitation and reduction in TUNEL-positive cells staining. On the other hand, amygdala TUNEL-positive cell numbers were not reduced in the Late group. Moreover, TNFalpha was significantly reduced in the amygdala of the Early group compared to the Control and Late groups. These results indicate that A(2A) adenosine receptor stimulation is associated with apoptosis regression in the amygdala following myocardial infarction.

Chemically Modified Tetracycline Improves Contractility in Porcine Coronary Ischemia/Reperfusion Injury

BACKGROUND

Reperfusion of ischemic myocardium has been implicated in extension of infarct size and deleterious clinical outcomes. Anti-inflammatory agents reduce this reperfusion injury. Chemically modified tetracycline-3 (CMT-3) (Collagenex Pharmaceuticals, Newtown, PA, USA) lacks antimicrobial properties yet retains anti-inflammatory activity. We examined infarct size and myocardial function in a porcine coronary artery occlusion/reperfusion model in CMT-3-treated and control animals.

METHODS

Yorkshire pigs (n = 8) underwent median sternotomy, pretreatment with heparin (300 U/kg and 67 U/kg/hr IV) and lidocaine (1 mg/kg IV) and were divided into two groups. Group one (n = 4) had the left anterior descending artery (LAD) occluded for 1 hour, after which it was reperfused for 2 hours. Group two (n = 4) had an identical protocol to group one except CMT-3 (2 mg/kg IV) was administered prior to occlusion of the LAD.

RESULTS

Animals receiving CMT-3 had significantly decreased infarct size in relation to the ventricular area-at-risk (AAR) (28 +/- 9% vs. 64 +/- 8%; p < 0.05). Myocardial contractile function was superior in the CMT-3 treatment, indicated by a higher cardiac index (2.9 +/- 0.3 vs. 2.0 +/- 0.3 L/min/m(2); p < 0.05) and stroke volume index (22 +/- 2 vs. 17 +/- 1 L/m(2)/beat; p < 0.05).

CONCLUSIONS

CMT-3 decreased infarct size in relation to the AAR resulting in relative preservation of contractility, suggesting CMT-3 may improve outcomes during myocardial ischemia reperfusion.

Aprotinin decreases ischemic damage during coronary revascularization

BACKGROUND AND AIM

This study sought to determine whether the favorable anti-inflammatory effects of aprotinin might limit ischemic damage during the revascularization of ischemic myocardium.

METHODS

Twenty pigs underwent 90 minutes of coronary occlusion followed by 45 minutes of blood cardioplegic arrest and 180 minutes of reperfusion. Ten animals received a loading dose of aprotinin (40,000 kallikrein inhibiting units/kg) during the start of coronary occlusion followed by an infusion of 20,000 kallikrein inhibiting units/kg/hour. Ten other animals received no aprotinin. Summary statistics are expressed as the mean +/- standard error.

RESULTS

The aprotinin-treated animals required less cardioversions for ventricular arrhythmias (1.0 +/- 0.7 vs. 3.6 +/- 0.6; p < 0.001), accumulated less lung water (1.0 +/- 0.2% change vs. 6.2 +/- 0.9% change; p = 0.038), had more complete coronary relaxation to bradykinin (34.1 +/- 5.9% change vs. 9.2 +/- 3.5% change; p = 0.01), and had reduced infarct size (area necrosis/area risk = 20 +/- 1.1% vs. 39 +/- 1.2%; p = 0.003).

CONCLUSIONS

Aprotinin limits ischemic injury during acute coronary revascularization by decreasing ventricular arrhythmias and lung edema, preserving endothelial function, and minimizing myocardial necrosis.

Biologics in the treatment of transplant rejection and ischemia/reperfusion injury: new applications for TNFalpha inhibitors?

Tumor necrosis factor (TNF)-alpha inhibitors have proven efficacy in various autoimmune diseases such as Crohn disease, rheumatoid arthritis, psoriasis, and ankylosing spondylitis. Indeed, some TNFalpha inhibitors have already been approved for the management of the inflammatory manifestations associated with Crohn disease and rheumatoid arthritis. These agents are increasingly used for treatment of corticosteroid-resistant graft-versus-host disease after bone marrow transplantation, and case reports have documented their efficacy in treating corticosteroid- and muromonab-resistant rejection after intestinal transplantation. Thus, the potential role of TNFalpha inhibitors in transplantation of other vascularized solid organs is worthy of investigation. Experimental evidence indicates that TNFalpha plays a key role in mediating ischemia/reperfusion (IR) injury after liver, kidney, intestine, heart, lung, and pancreas transplantation. TNFalpha was also identified as a marker cytokine during organ rejection. Single-center studies evaluating the role of TNFalpha inhibitors in kidney transplantation have been initiated but the results are not yet available. TNFalpha is known to be a contributing factor in kidney allograft rejection, and may have value in predicting the onset of steroid-resistant acute rejection after liver transplantation. Experimental and preliminary clinical data have shown that circulating levels of TNFalpha are increased during cardiac graft rejection, and indicate that TNFalpha plays a role in the pathogenesis of acute cardiac allograft rejection. Anti-TNFalpha therapy was shown to prolong cardiac allograft survival when used alone or in combination with other drugs. TNFalpha genotype has been strongly associated with mortality in humans due to acute cell-mediated heart transplant rejection. In addition, there is evidence for a genetic predisposition toward acute rejection after kidney and simultaneous kidney-pancreas transplantation. TNFalpha inhibition has been used successfully as part of an induction therapy for pancreatic islet cell transplantation. Apart from IR injury and acute rejection after lung transplantation, TNFalpha was also found to be involved in the pathoimmunology of obliterative bronchiolitis. In conclusion, a substantial body of experimental evidence and preliminary clinical data suggest that TNFalpha inhibitors may play an important role in solid-organ transplantation, both in the amelioration of IR injury and in the treatment and prevention of acute rejection. Pharmacodynamic monitoring and pharmacogenetic screening may help to identify patients most likely to benefit from TNFalpha blockade. Randomized controlled trials in patients undergoing solid-organ transplantation are needed to further elucidate the clinical value of TNFalpha inhibition.

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.