TNFα in myocardial ischemia/reperfusion: Damage vs. protection

Inflammation in Myocardial Ischemia/Reperfusion Injury: Underlying Mechanisms and Therapeutic Potential

Acute myocardial infarction (MI) occurs when blood flow to the myocardium is restricted, leading to cardiac damage and massive loss of viable cardiomyocytes. Timely restoration of coronary flow is considered the gold standard treatment for MI patients and limits infarct size; however, this intervention, known as reperfusion, initiates a complex pathological process that somewhat paradoxically also contributes to cardiac injury. Despite being a sterile environment, ischemia/reperfusion (I/R) injury triggers inflammation, which contributes to infarct expansion and subsequent cardiac remodeling and wound healing. The immune response is comprised of subsets of both myeloid and lymphoid-derived cells that act in concert to modulate the pathogenesis and resolution of I/R injury. Multiple mechanisms, including altered metabolic status, regulate immune cell activation and function in the setting of acute MI, yet our understanding remains incomplete. While numerous studies demonstrated cardiac benefit following strategies that target inflammation in preclinical models, therapeutic attempts to mitigate I/R injury in patients were less successful. Therefore, further investigation leveraging emerging technologies is needed to better characterize this intricate inflammatory response and elucidate its influence on cardiac injury and the progression to heart failure.

Acute heart failure as an adverse event of tumor necrosis factor inhibitor therapy in inflammatory bowel disease: A review of the literature

Tumor necrosis factor inhibitors (anti-TNFs) are widely used therapies for the treatment of inflammatory bowel diseases (IBD); however, their administration is not risk-free. Heart failure (HF), although rare, is a potential adverse event related to administration of these medications. However, the exact mechanism of development of HF remains obscure. TNFα is found in both healthy and damaged hearts. Its effects are concentration- and receptor-dependent, promoting either cardio-protection or cardiomyocyte apoptosis. Experimental rat models with TNFα receptor knockout showed increased survival rates, less reactive oxygen species formation, and improved diastolic left ventricle pressure. However, clinical trials employing anti-TNF therapy to treat HF had disappointing results, suggesting abolishment of the cardioprotective properties of TNFα, making cardiomyocytes susceptible to apoptosis and oxidation. Thus, patients with IBD who have risk factors should be screened for HF before initiating anti-TNF therapy. This review aims to discuss adverse events associated with the administration of anti-TNF therapy, with a focus on HF, and propose some approaches to avoid cardiac adverse events in patients with IBD.

Pre-operative kidney biomarkers and risks for death, cardiovascular and chronic kidney disease events after cardiac surgery: the TRIBE-AKI study

BACKGROUND

Soluble tumor necrosis factor receptor (sTNFR)1, sTNFR2, and plasma kidney injury molecule-1 (KIM-1) are associated with kidney events in patients with and without diabetes. However, their associations with clinical outcomes when obtained pre-operatively have not been explored.

METHODS

The TRIBE-AKI cohort study is a prospective, multicenter, cohort study of high-risk adults undergoing cardiac surgery. We assessed the associations between pre-operative concentrations of plasma sTNFR1, sTNFR2, and KIM-1 and post-operative long-term outcomes including mortality, cardiovascular events, and chronic kidney disease (CKD) incidence or progression after discharge.

RESULTS

Among 1378 participants included in the analysis with a median follow-up period of 6.7 (IQR 4.0-7.9) years, 434 (31%) patients died, 256 (19%) experienced cardiovascular events and out of 837 with available long-term kidney function data, 30% developed CKD. After adjustment for clinical covariates, each log increase in biomarker concentration was independently associated with mortality with 95% CI adjusted hazard ratios (aHRs) of 3.0 (2.3-4.0), 2.3 (1.8-2.9), and 2.0 (1.6-2.4) for sTNFR1, sTNFR2, and KIM-1, respectively. For cardiovascular events, the 95% CI aHRs were 2.1 (1.5-3.1), 1.9 (1.4-2.6) and 1.6 (1.2-2.1) for sTNFR1, sTNFR2 and KIM-1, respectively. For CKD events, the aHRs were 2.2 (1.5-3.1) for sTNFR1, 1.9 (1.3-2.7) for sTNFR2, and 1.7 (1.3-2.3) for KIM-1. Despite the associations, each of the biomarkers alone or in combination failed to result in robust discrimination on an absolute basis or compared to a clinical model.

CONCLUSION

sTNFR1, sTNFR2, and KIM-1 were independently associated with longitudinal outcomes after discharge from a cardiac surgery hospitalization including death, cardiovascular, and CKD events when obtained pre-operatively in high-risk individuals. Pre-operative plasma biomarkers could serve to assist during the evaluation of patients in whom cardiac surgery is planned.

α-Lipoic acid and amlodipine/perindopril combination potentiate the therapeutic effect of mesenchymal stem cells on isoproterenol induced cardiac injury in rats

Cardiac injury is a dangerous disease and become a greater issue in the forthcoming decades. The ultimate goal is to prevent the progression of heart failure and apoptotic processes. Cardiac tissue may regenerate itself but to certain extent depending on the number of resident stem cells that is limited. Thus, research had been focused on bone marrow derived stem cells (BM-MSCs) as a promising therapy in different types of tissues, including the heart. This study is designed not only to assess the therapeutic effect of BM-MSCs but also to improve their therapeutic effect in combination with antioxidant α-lipoic acid (ALA) and antihypertensive therapeutic drug form (AP) against isoproterenol-induced cardiac injury and compared with that of BM-MSCs alone. Cardiac injury was induced in 70 male rats by Isoproterenol (ISO was injected s.c. for four consecutive days). Experimental animals were divided into six ISO-treated groups beside a control non treated one. The six ISO-treated groups were divided into: ISO group, ISO+BM-MSCs group, ISO+ALA group, ISO+AP group, ISO+ALA+AP group and ISO+ALA+AP+BM-MSCs group, the last five groups were treated with the examined materials after one week of ISO injection. Isoproterenol significantly increased serum CK-MB, LDH activities, Troponin1 and TNF-α. Oxidative stress is evidenced by the increased MDA, NO and Caspase-3 activity associated with significant reduction of GSH content and SOD activity in cardiac tissue. Furthermore, mRNA expression of NFκB and iNOS were significantly up regulated and eNOS mRNA expression was down regulated. Administration of BM-MSCs, ALA and AP alone significantly mitigated the induced cardiac injury. Concomitant administration of ALA and AP after BM-MSCs induced a more pronounced improving effect on cardiac functions. In conclusion, the concomitant administration of ALA and AP after BM-MSCs infusion increases the cellular antioxidant levels of cardiac tissue that improves the repairing function of BM-MSCs.

Pro- and anti-inflammatory cytokines in post-infarction left ventricular remodeling

OBJECTIVES

Acute myocardial infarction (MI) leads to molecular, structural, geometric and functional changes in the heart during a process known as ventricular remodeling. Myocardial infarction is followed by an inflammatory response in which pro- and anti-inflammatory cytokines play a crucial role, particularly in left ventricular remodeling. This study aimed at evaluating serum concentrations of interleukin-8 (IL8), tumor-necrosis-factor-alpha (TNFα) and interleukin-10 (IL10), pro- and anti-inflammatory cytokines, and at correlating them with left ventricular remodeling as assessed by echocardiographic parameters.

METHODS

In a case-control study 30 MI patients were compared with 30 healthy controls. Serum concentrations of IL8, TNFα and IL10 were measured on day 2 and day 30 post-MI by chemiluminescence immunoassay and correlated with echocardiographic parameters.

RESULTS

There was an increase of IL8, and TNFα together with a decrease of IL10 at both time points. IL8 was negatively correlated with the left ventricular end-diastolic diameter (LVEDD) and positively with left ventricular systolic volume. IL10 was negatively correlated with LVEDD and left atrial volume 30days post-MI.

CONCLUSION

The increase of pro-inflammatory cytokines TNFα and IL8 was accompanied by decreased anti-inflammatory IL10. This imbalance between pro- and anti-inflammatory cytokines might contribute to the progression of left ventricular remodeling and may lead to heart failure.

Reduced acute myocardial ischemia-reperfusion injury in IL-6-deficient mice employing a closed-chest model

Objective and design

We examined the role of IL-6 in the temporal development of cardiac ischemia–reperfusion injury employing a closed-chest I/R model.

Materials/methods

Infarction, local and systemic inflammation, neutrophil infiltration, coagulation and ST elevation/resolution were compared between wild-type (WT) and IL-6-deficient (IL-6^−/−) mice after 1 h ischemia and 0, ½, 3, and 24 h reperfusion.

Results

IL-6 deficiency reduced infarct size at 3 h reperfusion (28.8 ± 4.5 % WT vs 17.6 ± 2.5 % IL-6^−/−), which reduction persisted and remained similar at 24 h reperfusion (25.1 ± 3.0 % WT vs 14.6 ± 4.4 % IL-6^−/−). Serum Amyloid A was reduced at 24 h reperfusion only (57.5 ± 4.9 WT vs 24.8 ± 5.6 ug/ml IL-6^−/− mice). Cardiac cytokines (IL-6, IL-1β and TNFα) peaked at 3 h reperfusion, but IL-1β and TNFα levels were unaffected by IL-6 deficiency. Significant neutrophil influx was only detected at 24 h reperfusion and was similar for WT and IL-6^−/−. Tissue factor peaked at 24 h reperfusion, whereas fibrin/fibrinogen peaked at 3 h reperfusion and was completely resolved at 24 h reperfusion; both coagulation factors were unaltered by IL-6 deficiency. Prolonged ST elevation was observed during ischemia that completely resolved for both genotypes at early reperfusion.

Conclusions

The data suggest that, in the absence of major surgical intervention, IL-6 contributes to the development of infarct size in the early phase of reperfusion; this contribution did not depend on neutrophil influx, IL-1β and TNFα, tissue factor and fibrin.

Non-invasive technology that improves cardiac function after experimental myocardial infarction: Whole Body Periodic Acceleration (pGz)

Myocardial infarction (MI) may produce significant inflammatory changes and adverse ventricular remodeling leading to heart failure and premature death. Pharmacologic, stem cell transplantation, and exercise have not halted the inexorable rise in the prevalence and great economic costs of heart failure despite extensive investigations of such treatments. New therapeutic modalities are needed. Whole Body Periodic Acceleration (pGz) is a non-invasive technology that increases pulsatile shear stress to the endothelium thereby producing several beneficial cardiovascular effects as demonstrated in animal models, normal humans and patients with heart disease. pGz upregulates endothelial derived nitric oxide synthase (eNOS) and its phosphorylation (p-eNOS) to improve myocardial function in models of myocardial stunning and preconditioning. Here we test whether pGz applied chronically after focal myocardial infarction in rats improves functional outcomes from MI. Focal MI was produced by left coronary artery ligation. One day after ligation animals were randomized to receive daily treatments of pGz for four weeks (MI-pGz) or serve as controls (MI-CONT), with an additional group as non-infarction controls (Sham). Echocardiograms and invasive pressure volume loop analysis were carried out. Infarct transmurality, myocardial fibrosis, and markers of inflammatory and anti-inflammatory cytokines were determined along with protein analysis of eNOS, p-eNOS and inducible nitric oxide synthase (iNOS).At four weeks, survival was 80% in MI-pGz vs 50% in MI-CONT (p< 0.01). Ejection fraction and fractional shortening and invasive pressure volume relation indices of afterload and contractility were significantly better in MI-pGz. The latter where associated with decreased infarct transmurality and decreased fibrosis along with increased eNOS, p-eNOS. Additionally, MI-pGz had significantly lower levels of iNOS, inflammatory cytokines (IL-6, TNF-α), and higher level of anti-inflammatory cytokine (IL-10). pGz improved survival and contractile performance, associated with improved myocardial remodeling. pGz may serve as a simple, safe, non-invasive therapeutic modality to improve myocardial function after MI.

Up-regulation of mRNA ventricular PRNP prion protein gene expression in air pollution highly exposed young urbanites: endoplasmic reticulum stress, glucose regulated protein 78, and nanosized particles

Mexico City Metropolitan Area children and young adults exposed to high concentrations of air pollutants including fine and ultrafine particulate matter (PM) vs. clean air controls, exhibit myocardial inflammation and inflammasome activation with a differential right and left ventricular expression of key inflammatory genes and inflammasomes. We investigated the mRNA expression levels of the prion protein gene PRNP, which plays an important role in the protection against oxidative stress and metal toxicity, and the glucose regulated protein 78, a key protein in endoplasmic reticulum (ER) stress signaling, in ventricular autopsy samples from 30 children and young adults age 19.97 ± 6.8 years with a lifetime of low (n:4) vs. high (n:26) air pollution exposures. Light microscopy and transmission electron microscopy studies were carried out in human ventricles, and electron microscopy studies were also done in 5 young, highly exposed Mexico City dogs. There was significant left ventricular PRNP and bi-ventricular GRP78 mRNA up-regulation in Mexico City young urbanites vs. controls. PRNP up-regulation in the left ventricle was significantly different from the right, p < 0.0001, and there was a strong left ventricular PRNP and GRP78 correlation (p = 0.0005). Marked abnormalities in capillary endothelial cells, numerous nanosized particles in myocardial ER and in abnormal mitochondria characterized the highly exposed ventricles. Early and sustained cardiac ER stress could result in detrimental irreversible consequences in urban children, and while highly complex systems maintain myocardial homeostasis, failure to compensate for chronic myocardial inflammation, oxidative and ER stress, and particles damaging myocardial organelles may prime the development of pathophysiological cardiovascular states in young urbanites. Nanosized PM could play a key cardiac myocyte toxicity role.

Influence of tumour necrosis factor alpha on the outcome of ischaemic postconditioning in the presence of obesity and diabetes

Obesity and diabetes contribute to cardiovascular disease and alter cytokine profile. The cytokine, tumour necrosis factor alpha (TNFα), activates a protective signalling cascade during ischaemic postconditioning (IPostC). However, most successful clinical studies with IPostC have not included obese and/or diabetic patients. We aimed to investigate the influence of TNFα on the outcome of IPostC in obese or diabetic mice. TNF knockout or wildtype mice were fed for 11 weeks with a high carbohydrate diet (HCD) to induce modest obesity. Diabetes was induced in a separate group by administration of a single intraperitoneal injection of streptozotocin. Hearts were then isolated and subjected to ischaemia (35 min of global ischaemia) followed by 45 min of reperfusion. HCD increased body weight, plasma insulin and leptin levels while the glucose level was unchanged. In streptozotocin-treated mice, blood glucose, plasma leptin and insulin were altered. Control, obese or diabetic mice were protected with IPostC in wiltype animals. In TNF knockout mice, IPostC failed to protect control and diabetic hearts while a slight protection was observed in obese hearts. Our data confirm a bidirectional role for TNFα associated with the severity of concomitant comorbidities and suggest that diabetic and/or modestly obese patients may still benefit from IPostC.

Intra-city Differences in Cardiac Expression of Inflammatory Genes and Inflammasomes in Young Urbanites: A Pilot Study

Southwest Mexico City (SWMC) air pollution is characterized by high concentrations of ozone and particulate matter < 10 μm (PM₁₀) containing lipopolysaccharides while in the North PM_2.5 is high. These intra-city differences are likely accounting for higher CD14 and IL-1β in SWMC v NMC mice myocardial expression. This pilot study was designed to investigate whether similar intra-city differences exist in the levels of myocardial inflammatory genes in young people. Inflammatory mediator genes and inflammasome arrays were measured in right and left autopsy ventricles of 6 southwest/15 north (18.5 ± 2.6 years) MC residents after fatal sudden accidental deaths. There was a significant S v N right ventricle up-regulation of IL-1β (p=0.008), TNF-α (p=0.001), IL-10 (p=0.001), and CD14 (p=0.002), and a left ventricle difference in TNF-α (p=0.007), and IL-10 (p=0.02). SW right ventricles had significant up-regulation of NLRC1, NLRP3 and of 29/84 inflammasome genes, including NOD factors and caspases. There was significant degranulation of mast cells both in myocardium and epicardial nerve fibers. Differential expression of key inflammatory myocardial genes and inflammasomes are influenced by the location of residence. Myocardial inflammation and inflammasome activation in young hearts is a plausible pathway of heart injury in urbanites and adverse effects on the cardiovascular system are expected.

Comparison of cardioprotective and anti-inflammatory effects of ischemia pre- and postconditioning in rats with myocardial ischemia-reperfusion injury

OBJECTIVE

To compare cardioprotective and anti-inflammatory effects of ischemia preconditioning (IPC) and ischemia postconditioning (IPOC) in a rat myocardial ischemia-reperfusion injury (IRI) model.

METHODS

Forty Sprague-Dawley rats were randomly divided equally into four groups. In the groups other than the sham group, the left anterior descending coronary artery was ligated for 30 min followed by a 180 min reperfusion in vivo. The control group was subjected to no additional intervention, the IPC group to three cycles of 5 min ischemia separated by 5 min reperfusion before the index ischemia and the IPOC group to three cycles of 10 s ischemia separated by 10 s reperfusion immediately after the end of the index ischemia. Hemodynamic changes during the ischemia and reperfusion were recorded. At 180 min of reperfusion, serum concentrations of troponin I (TnI), tumor necrosis factor α (TNF-α) and high-mobility group box 1 (HMGB-1) were assayed, and the infarction size was assessed by Evans blue and triphenyltetrazolium chloride staining.

RESULTS

Compared to the control group, infarct size and serum concentrations of TnI, TNF-α and HMGB1 at 180 min of reperfusion were significantly reduced in the IPC and IPOC groups. However, infarct size and serum concentrations of TNF-α and HMGB1 at 180 min of reperfusion were significantly increased in the IPOC group compared to the IPC group.

CONCLUSIONS

In the rats with myocardial IRI in vivo, both IPC and IPOC can produce significant cardioprotective and anti-inflammatory effects. However, cardioprotective and anti-inflammatory effects provided by IPOC are weaker than with IPC.

Urban air pollution produces up-regulation of myocardial inflammatory genes and dark chocolate provides cardioprotection

Air pollution is a serious environmental problem. Elderly subjects show increased cardiac morbidity and mortality associated with air pollution exposure. Mexico City (MC) residents are chronically exposed to high concentrations of fine particulate matter (PM(2.5)) and PM-associated lipopolysaccharides (PM-LPS). To test the hypothesis that chronic exposure to urban pollution produces myocardial inflammation, female Balb-c mice age 4 weeks were exposed for 16 months to two distinctly different polluted areas within MC: southwest (SW) and northwest (NW). SW mice were given either no treatment or chocolate 2g/9.5 mg polyphenols/3 times per week. Results were compared to mice kept in clean air. Key inflammatory mediator genes: cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), and the LPS receptor CD14 (cluster of differentiation antigen 14) were measured by real-time polymerase chain reaction. Also explored were target NFκB (nuclear factor κB), oxidative stress and antioxidant defense genes. TNF-α, IL-6, and COX-2 were significantly increased in both NW and SWMC mice (p=0.0001). CD14 was up-regulated in SW mice in keeping with the high exposures to particulate matter associated endotoxin. Chocolate administration resulted in a significant down-regulation of TNF-α (p<0.0001), IL-6 (p=0.01), and IL-1β (p=0.02). The up-regulation of antioxidant enzymes and the down-regulation of potent oxidases, toll-like receptors, and pro-apoptotic signaling genes completed the protective profile. Exposure to air pollution produces up-regulation of inflammatory myocardial genes and endotoxin plays a key role in the inflammatory response. Regular consumption of dark chocolate may reduce myocardial inflammation and have cardioprotective properties in the setting of air pollution exposures.

AMP-activated protein kinase confers protection against TNF-{alpha}-induced cardiac cell death

AIMS

Although a substantial role for 5' adenosine monophosphate-activated protein kinase (AMPK) has been established in regulating cardiac metabolism, a less studied action of AMPK is its ability to prevent cardiac cell death. Using established AMPK activators like dexamethasone (DEX) or metformin (MET), the objective of the present study was to determine whether AMPK activation prevents tumour necrosis factor-alpha (TNF-alpha) induced apoptosis in adult rat ventricular cardiomyocytes.

METHODS AND RESULTS

Cardiomyocytes were incubated with DEX, MET, or TNF-alpha for varying durations (0-12 h). TNF-alpha-induced cell damage was evaluated by measuring caspase-3 activity and Hoechst staining. Protein and gene estimation techniques were employed to determine the mechanisms mediating the effects of AMPK activators on TNF-alpha-induced cardiomyocyte apoptosis. Incubation of myocytes with TNF-alpha for 8 h has increased caspase-3 activation and apoptotic cell death, an effect that was abrogated by DEX and MET. The beneficial effect of DEX and MET was associated with stimulation of AMPK, which led to a rapid and sustained increase in Bad phosphorylation. This event reduced the interaction between Bad and Bcl-xL, limiting cytochrome c release and caspase-3 activation. Addition of Compound C to inhibit AMPK reduced Bad phosphorylation and prevented the beneficial effects of AMPK against TNF-alpha-induced cytotoxicity.

CONCLUSION

Our data demonstrate that although DEX and MET are used as anti-inflammatory agents or insulin sensitizers, respectively, their common property to phosphorylate AMPK promotes cardiomyocyte cell survival through its regulation of Bad and the mitochondrial apoptotic mechanism.

Activation of the protective Survivor Activating Factor Enhancement (SAFE) pathway against reperfusion injury: Does it go beyond the RISK pathway?

Lethal reperfusion injury is now recognized as a major limitation of current reperfusion therapy by primary percutaneous coronary intervention for acute myocardial infarction. Interestingly, the heart itself is capable of activating an intrinsic protective signaling programme to limit cell death during reperfusion. Tumor necrosis factor alpha (TNFalpha) is a cytokine generally thought to contribute to myocardial dysfunction in ischemia/reperfusion or heart failure. We review evidence that TNFalpha can paradoxically initiate the activation of a novel protective pathway against reperfusion injuries that we have named the Survivor Activating Factor Enhancement (SAFE) pathway. This path requires the activation of the signal transducer and activator of transcription 3 (STAT-3) and it can successfully lessen cardiomyocyte death at the time of reperfusion, independently of the activation of the already well-described Reperfusion Injury Salvage Kinase (RISK) pathway (which includes activation of Akt and Erk 1/2). Emerging knowledge on this novel protective path is presented here with the aim of unravelling its interaction with the RISK pathway and its potential human application to protect against lethal reperfusion injury.