Pexelizumab and the APEX AMI trial

Targeting Gαi2 in neutrophils protects from myocardial ischemia reperfusion injury

Neutrophils are not only involved in immune defense against infection but also contribute to the exacerbation of tissue damage after ischemia and reperfusion. We have previously shown that genetic ablation of regulatory Gαi proteins in mice has both protective and deleterious effects on myocardial ischemia reperfusion injury (mIRI), depending on which isoform is deleted. To deepen and analyze these findings in more detail the contribution of Gαi2 proteins in resident cardiac vs circulating blood cells for mIRI was first studied in bone marrow chimeras. In fact, the absence of Gαi2 in all blood cells reduced the extent of mIRI (22,9% infarct size of area at risk (AAR) Gnai2-/- → wt vs 44.0% wt → wt; p < 0.001) whereas the absence of Gαi2 in non-hematopoietic cells increased the infarct damage (66.5% wt → Gnai2-/- vs 44.0% wt → wt; p < 0.001). Previously we have reported the impact of platelet Gαi2 for mIRI. Here, we show that infarct size was substantially reduced when Gαi2 signaling was either genetically ablated in neutrophils/macrophages using LysM-driven Cre recombinase (AAR: 17.9% Gnai2fl/fl LysM-Cre+/tg vs 42.0% Gnai2fl/fl; p < 0.01) or selectively blocked with specific antibodies directed against Gαi2 (AAR: 19.0% (anti-Gαi2) vs 49.0% (IgG); p < 0.001). In addition, the number of platelet-neutrophil complexes (PNCs) in the infarcted area were reduced in both, genetically modified (PNCs: 18 (Gnai2fl/fl; LysM-Cre+/tg) vs 31 (Gnai2fl/fl); p < 0.001) and in anti-Gαi2 antibody-treated (PNCs: 9 (anti-Gαi2) vs 33 (IgG); p < 0.001) mice. Of note, significant infarct-limiting effects were achieved with a single anti-Gαi2 antibody challenge immediately prior to vessel reperfusion without affecting bleeding time, heart rate or cellular distribution of neutrophils. Finally, anti-Gαi2 antibody treatment also inhibited transendothelial migration of human neutrophils (25,885 (IgG) vs 13,225 (anti-Gαi2) neutrophils; p < 0.001), collectively suggesting that a therapeutic concept of functional Gαi2 inhibition during thrombolysis and reperfusion in patients with myocardial infarction should be further considered.

Immune cells in cardiac repair and regeneration

The immune system is fundamental to tissue homeostasis and is the first line of defense following infection, injury or disease. In the damaged heart, large numbers of immune cells are recruited to the site of injury. These cells play an integral part in both repair by scar formation and the initiation of tissue regeneration. They initially assume inflammatory phenotypes, releasing pro-inflammatory cytokines and removing dead and dying tissue, before entering a reparative stage, replacing dead muscle tissue with a non-contractile scar. In this Review, we present an overview of the innate and adaptive immune response to heart injury. We explore the kinetics of immune cell mobilization following cardiac injury and how the different innate and adaptive immune cells interact with one another and with the damaged tissue. We draw on key findings from regenerative models, providing insight into how to support a robust immune response permissible for cardiac regeneration. Finally, we consider how the latest technological developments can offer opportunities for a deeper and unbiased functional understanding of the immune response to heart disease, highlighting the importance of such knowledge as the basis for promoting regeneration following cardiac injury in human patients.

Exosomes Derived from Mesenchymal Stem Cells Protect the Myocardium Against Ischemia/Reperfusion Injury Through Inhibiting Pyroptosis

Objective

Mesenchymal stem cells (MSCs) show unique advantages in cardiomyocyte repairment. Exosomes derived from MSCs can enhance the viability of myocardial cells after ischemia/reperfusion (I/R) injury and regulate inflammation response. The study was designed to ascertain whether MSCs-exo protect the myocardium against I/R injury through inhibiting pyroptosis, and the underlying mechanisms.

Methods and Results

Experiments were carried out in H/R and I/R model. Cell viability was inhibited and NLRP3 and caspase1 protein levels were upregulated in H/R model. However, MSCs could inhibit cell apoptosis and pyroptosis in H/R model. Moreover, we used MSCs-exo to treated H/R model, and flow cytometric analysis results showed the inhibition function of MSCs-exo on cell apoptosis, and Western blot data suggested that NLRP3 and Caspase-1 expressions were downregulated in H/R model. Furthermore, exosomal miR-320b targeted NLRP3 protein, and MSCs-exo OE could inhibit NLRP3 expression and pyroptosis in H/R. In addition, the inhibition function of MSCs-exo on pyroptosis also was found in I/R model, and HE and Tunel staining also got similar results.

Conclusion

Exosomes derived from mesenchymal stem cells could protect the myocardium against ischemia/reperfusion injury through inhibiting pyroptosis.

The Role of Extracellular DNA and Histones in Ischaemia-Reperfusion Injury of the Myocardium

Despite an increase in the rates of survival in patients suffering myocardial infarction, as yet there is no therapy specifically targeting ischaemia and reperfusion injury of the myocardium. With a greater understanding of immune activation during infarction, more potential treatment targets are now being identified. The innate immune system is believed to play an important role in the myocardium after ischaemia-driven cardiomyocyte death. The release of intracellular contents including DNA into the extracellular space during necrosis and cell rupture is now believed to create a pro-inflammatory milieu which propagates the inflammatory process. DNA and DNA fragments have been shown to activate the innate immune system by acting as Danger-Associated Molecular Patterns (DAMPs), which act as ligands on toll-like receptors (TLRs). Stimulation of TLRs, in turn, can activate intracellular cell death pathways such as pyroptosis. Here, we review the role of DNA fragments during ischaemia and reperfusion, and assess their potential as a target in the quest to preserve cardiomyocyte viability following myocardial infarction.

Colchicine: an affordable anti-inflammatory agent for atherosclerosis

PURPOSE OF REVIEW

Inflammation has been shown to be central to the development and progression of atherosclerosis. Despite detailed understanding of its central role and the cellular dynamics, which contribute to atherosclerotic inflammation, there has been slow progress in finding suitable agents to treat it. The recent CANTOS trial showed that the interleukin-1β inhibitor canakinumab can improve outcomes after acute coronary syndromes. Being a monoclonal antibody, it is expensive and inconvenient to administer for long-term treatment. This review summarizes recent work in finding effective, affordable alternatives to canakinumab.

RECENT FINDINGS

Statin drugs have anti-inflammatory properties but separating their LDL lowering effect from their anti-inflammatory effect has been difficult. Drugs acting on targets outside of the interleukin-1β (IL-1β) pathway have been tested without finding a suitable candidate. Following the proof of principle provided by the success of canakinumab, other candidates targeting the IL-1β pathway are undergoing detailed evaluation. The most likely candidates are low-dose methotrexate and low-dose colchicine. The potential mechanisms and ongoing clinical trials are described.

SUMMARY

Targeting the IL-1β pathway has already been successful with canakinumab but its expense and inconvenience of administration may limit its widespread uptake for controlling inflammation in atherosclerosis. Low-dose methotrexate and low-dose colchicine are affordable and more accessible alternatives, currently undergoing detailed evaluation for safety and efficacy in large randomized controlled trials.

Advances in Coronary No-Reflow Phenomenon-a Contemporary Review

PURPOSE OF REVIEW

Coronary artery no-reflow phenomenon is an incidental outcome of percutaneous coronary intervention in patients presenting with acute myocardial infarction. Despite advances in pharmacologic and non-pharmacologic therapies, coronary no-reflow phenomenon occurs more commonly than desired. It often results in poor clinical outcomes and remains as a relevant consideration in the cardiac catheterization laboratory. In this systematic review, we have sought to discuss the topic in detail, and to relay the most recent discoveries and data on management of this condition.

RECENT FINDINGS

We discuss several pharmacologic and non-pharmacologic treatments used in the prevention and management of coronary no-reflow and microvascular obstruction. Covered topics include the understanding of pharmacologic mechanisms of current and future agents, and recent discoveries that may result in the development of future treatment options. We conclude that the pathophysiology of coronary no-reflow phenomenon and microvascular obstruction still remains incompletely understood, although several plausible theories have led to the current standard of care for its management. We also conclude that coronary no-reflow phenomenon and microvascular obstruction must be recognized as a multifactorial condition that has certain predispositions and characteristics, therefore its prevention and treatment must begin pre-procedurally and be multi-faceted including certain medications and operator techniques in the cardiac catheterization laboratory.

White Wine Consumption Influences Inflammatory Phase of Repair After Myocardial Infarction in Rats

Effects of white wine (WW) consumption on the expression of inflammatory markers/mediators (MMP-2, MMP-9, NF-ĸB p65 and TGF-β1) in myocardial tissue after experimentally induced permanent myocardial ischemia was investigated. Male Sprague-Dawley rats were given either a combination of WW and water or only water, for 28 days. After coronary ligation, animals were left to survive for 24 hours. Three representative areas: infarct/ischemic, peri-infarct/border zone, and control/non-ischemic zones were analyzed for expression of immunoreactivity by measuring the threshold area % of signal density. For MMP-9, significantly smaller expression was found in all 3 zones of wine drinking animals (P < 0.001). There was no difference in MMP-2 immunoreactivity between the 2 groups, except in peri-infarct zones, where the signal was significantly decreased (P < 0.001). The same pattern of expression was found for the NF-κB p65 signal, although no differences between experimental groups were observed for TGF-β1. White wine consumption decreases the expression of the 3 investigated inflammatory markers/mediators in the peri-infarct zone, suggesting its significant modulatory effect. For MMP-9 and MMP-2, expression was similar to the effect of postischemic reperfusion. No effect on TGF-β1 was observed, highlighting its role in being the master-switch, changing from the inflammatory to the proliferative stage of infarct healing.

TREM-1 and its potential ligands in non-infectious diseases: from biology to clinical perspectives

Triggering receptor expressed on myeloid cells-1 (TREM-1) is expressed on the majority of innate immune cells and to a lesser extent on parenchymal cells. Upon activation, TREM-1 can directly amplify an inflammatory response. Although it was initially demonstrated that TREM-1 was predominantly associated with infectious diseases, recent evidences shed new light into its role in sterile inflammatory diseases. Indeed, TREM-1 receptor and its signaling pathways contribute to the pathology of several non-infectious acute and chronic inflammatory diseases, including atherosclerosis, ischemia reperfusion-induced tissue injury, colitis, fibrosis and cancer. This review, aims to give an extensive overview of TREM-1 in non-infectious diseases, with the focus on the therapeutic potential of TREM-1 intervention strategies herein. In addition, we provide the reader with a functional enrichment analysis of TREM-1 signaling pathway and potential TREM-1 ligands in these diseases, obtained via in silico approach. We discuss pre-clinical studies which show that TREM-1 inhibition, via synthetic soluble TREM-1 protein mimickers, is effective in treating (preventing) specific inflammatory disorders, without significant effects on antibacterial response. Further research aimed at identifying specific TREM-1 ligands, in different inflammatory disorders, is required to further unravel the role of this receptor, and explore new avenues to modulate its function.

Is Cardioprotection Dead?

For >4 decades, the holy grail in the treatment of acute myocardial infarction has been the mitigation of lethal injury. Despite promising initial results and decades of investigation by the cardiology research community, the only treatment with proven efficacy is early reperfusion of the occluded coronary artery. The remarkable record of failure has led us and others to wonder if cardioprotection is dead. The path to translation, like the ascent to Everest, is certainly littered with corpses. We do, however, highlight a therapeutic principle that provides a glimmer of hope: cellular postconditioning. Administration of cardiosphere-derived cells after reperfusion limits infarct size measured acutely, while providing long-term structural and functional benefits. The recognition that cell therapy may be cardioprotective, and not just regenerative, merits further exploration before we abandon the pursuit entirely.

Remote Ischemic Conditioning for Patients With STEMI

ST-segment elevation myocardial infarction (STEMI) remains a leading cause of death and morbidity, despite declining incidence and improved short-term outcome in many countries. Although mortality declines in developed countries with easy and fast access to optimized treatment, development of heart failure often remains a challenge in survivors and still approaches 10% at 1 year. Rapid admission and acute interventional treatment combined with modern antithrombotic pharmacologic therapy frequently establish complete reperfusion and acutely stabilize the patient, but the reperfusion itself adds further to the damage in the myocardium compromising the long-term outcome. Reperfusion injury is believed to be a significant-if not the dominant-contributor to the net injury resulting from STEMI and has become a major focus of research in recent years. Despite a plethora of pharmacological and mechanical interventions showing consistent reduction of reperfusion injury in experimental models, translation into a clinical setting has been challenging. In patients, attempts to modify reperfusion injury by pharmacological strategies have largely been unsuccessful, and focus is increasingly directed toward mechanical modalities. Remote ischemic conditioning of the heart is achieved by repeated brief interruption of the blood supply to a distant part of the body, most frequently the arm. At present, remote ischemic conditioning is the most promising adjuvant therapy to reduce reperfusion injury in patients with STEMI. In this review, we discuss the results of clinical trials investigating the effect of remote ischemic conditioning in patients admitted with STEMI and potential reasons for its apparent superiority to current pharmacologic adjuvant therapies.

Nanoparticle-Mediated Delivery of Irbesartan Induces Cardioprotection from Myocardial Ischemia-Reperfusion Injury by Antagonizing Monocyte-Mediated Inflammation

Myocardial ischemia-reperfusion (IR) injury limits the therapeutic effect of early reperfusion therapy for acute myocardial infarction (AMI), in which the recruitment of inflammatory monocytes plays a causative role. Here we develop bioabsorbable poly-lactic/glycolic acid (PLGA) nanoparticles incorporating irbesartan, an angiotensin II type 1 receptor blocker with a peroxisome proliferator-activated receptor (PPAR)γ agonistic effect (irbesartan-NP). In a mouse model of IR injury, intravenous PLGA nanoparticles distribute to the IR myocardium and monocytes in the blood and in the IR heart. Single intravenous treatment at the time of reperfusion with irbesartan-NP (3.0 mg kg(-1) irbesartan), but not with control nanoparticles or irbesartan solution (3.0 mg kg(-1)), inhibits the recruitment of inflammatory monocytes to the IR heart, and reduces the infarct size via PPARγ-dependent anti-inflammatory mechanisms, and ameliorates left ventricular remodeling 21 days after IR. Irbesartan-NP is a novel approach to treat myocardial IR injury in patients with AMI.

Post-myocardial infarct inflammation and the potential role of cell therapy

Myocardial infarction triggers reparative inflammatory processes programmed to repair damaged tissue. However, often additional injury to the myocardium occurs through the course of this inflammatory process, which ultimately can lead to heart failure. The potential beneficial effects of cell therapy in treating cardiac ischemic disease, the number one cause of death worldwide, are being studied extensively, both in clinical trials using adult stem cells as well as in fundamental research on cardiac stem cells and regenerative biology. This review summarizes the current knowledge on molecular and cellular processes implicated in post-infarction inflammation and discusses the potential beneficial role cell therapy might play in this process. Due to its immunomodulatory properties, the mesenchymal stromal cell is a candidate to reverse the disease progression of the infarcted heart towards heart failure, and therefore is emphasized in this review.

Adjuvant treatment with dexamethasone plus anti-C5 antibodies improves outcome of experimental pneumococcal meningitis: a randomized controlled trial

Background

We compared adjunctive treatment with placebo, dexamethasone, anti-C5 antibodies, and the combination of dexamethasone plus anti-C5 antibodies in experimental pneumococcal meningitis.

Methods

In this prospective, investigator-blinded, randomized trial, 96 mice were infected intracisternally with 10⁷ CFU/ml Streptococcus pneumoniae serotype 3, treated with intraperitoneal ceftriaxone at 20 h, and randomly assigned to intraperitoneal adjunctive treatment with placebo (saline), dexamethasone, anti-C5 antibodies, or dexamethasone plus anti-C5 antibodies. The primary outcome was survival during a 72-h observational period that was analyzed with the log-rank test. Secondary outcome was clinical severity, scored on a validated scale using a linear mixed model.

Results

Mortality rates were 16 of 16 mice (100 %) in the placebo group, 12 of 15 mice (80 %) in the dexamethasone group, 25 of 31 mice (80 %) in the anti-C5 antibody group, and 18 of 30 mice (60 %) in the dexamethasone plus anti-C5 antibody group (Fisher’s exact test for overall difference, P = .012). Mortality of mice treated with dexamethasone plus anti-C5 antibodies was lower compared to the anti-C5 antibody-treated mice (log-rank P = .039) and dexamethasone-treated mice (log-rank P = .040). Clinical severity scores for the dexamethasone plus anti-C5 antibody-treated mice increased more slowly (0.199 points/h) as compared to the anti-C5 antibody-treated mice (0.243 points/h, P = .009) and dexamethasone-treated mice (0.249 points/h, P = .012). Modeling of severity data suggested an additive effect of dexamethasone and anti-C5 antibodies.

Conclusion

Adjunctive treatment with dexamethasone plus anti-C5 antibodies improves survival in severe experimental meningitis caused by S. pneumoniae serotype 3, posing an important new treatment strategy for patients with pneumococcal meningitis.

Intracoronary electrocardiogram ST-segment elevation in patients with non-ST-segment elevation myocardial infarction and its association with culprit lesion location and myocardial injury

AIMS

An intracoronary electrocardiogram (IC-ECG) is a sensitive method to detect local myocardial ischaemia. We investigated the prevalence of IC-ECG ST-segment elevation (STE) with respect to culprit lesion location in patients with non-ST-segment elevation myocardial infarction (NSTEMI) and its relationship with elevated levels of cardiac biomarkers.

METHODS AND RESULTS

We examined 87 NSTEMI patients who underwent IC-ECG recording by locating the insulated polymer-coated guidewire distal to the culprit lesion before percutaneous coronary intervention (PCI). Cardiac biomarkers were serially examined. IC-ECG STE was observed in 24 patients (27.6%) before PCI, and was significantly more frequent in patients with LCx culprit lesions (LAD vs. LCx vs. RCA, 12.1% vs. 53.3% vs. 16.7%; p<0.001). Peak cardiac troponin I (cTnI) values were associated with IC-ECG STE, ejection fraction (EF), cTnI values on admission, and type B2/C lesions. In multivariate analysis, IC-ECG STE (odds ratio [OR], 5.04; 95% confidence intervals [CI]: 1.51-16.85; p=0.009), and EF (OR, 0.95; 95% CI: 0.90-1.00; p=0.043) were predictors of greater peak cTnI values.

CONCLUSIONS

IC-ECG STE was not uncommon in NSTEMI patients, particularly those with LCx culprit lesions. IC-ECG monitoring before PCI may help identify NSTEMI patients with high risk of greater myocardial injury.

Remote conditioning the heart overview: translatability and mechanism

Conditioning the heart to resist predictable and unpredictable ischaemia-reperfusion (IR) injury is one of the fastest growing areas of bench to bedside research within cardiology. Basic science has provided important insights into signalling pathways and protective mechanisms in the heart, and a growing number of clinical studies have, with important exceptions, shown the potential applicability and beneficial effect of various mechanical conditioning strategies achieved by intermittent short-lasting-induced ischaemia of the heart itself or a remote tissue. Remote ischaemic conditioning (RIC) in particular has been utilized in a number of clinical settings with promising results. However, while many novel 'downstream' mechanisms of RIC have been discovered, translation to pharmacological conditioning has not yet been convincingly demonstrated in clinical studies. One explanation for this apparent failure may be that most pharmacological approaches mimic a single instrument in a complex orchestra activated by mechanical conditioning. Recent studies, however, provide important insights into upstream events occurring in RIC, which may allow for development of drugs activating more complex systems of biological organ protection. With this review, we will systematically examine the first generation of pharmacological cardioprotection studies and then provide a summary of the recent discoveries in basic science that could illuminate the path towards more advanced approaches in the next generation of pharmacological agents that may work by reproducing the diverse effects of RIC, thereby providing protection against IR injury.

The immune system and the remodeling infarcted heart: cell biological insights and therapeutic opportunities

Extensive necrosis of ischemic cardiomyocytes in the infarcted myocardium activates the innate immune response triggering an intense inflammatory reaction. Release of danger signals from dying cells and damaged matrix activates the complement cascade and stimulates Toll-like receptor/interleukin-1 signaling, resulting in the activation of the nuclear factor-κB system and induction of chemokines, cytokines, and adhesion molecules. Subsequent infiltration of the infarct with neutrophils and mononuclear cells serves to clear the wound from dead cells and matrix debris, while stimulating reparative pathways. In addition to its role in repair of the infarcted heart and formation of a scar, the immune system is also involved in adverse remodeling of the infarcted ventricle. Overactive immune responses and defects in suppression, containment, and resolution of the postinfarction inflammatory reaction accentuate dilative remodeling in experimental models and may be associated with chamber dilation, systolic dysfunction, and heart failure in patients surviving a myocardial infarction. Interventions targeting the inflammatory response to attenuate adverse remodeling may hold promise in patients with myocardial infarction that exhibit accentuated, prolonged, or dysregulated immune responses to the acute injury.

Pharmacological attenuation of myocardial reperfusion injury in a closed-chest porcine model: a systematic review

Myocardial ischemia-reperfusion injury is a clinical challenge in interventional cardiology, and at the moment, no pharmacological agent is universally accepted in the prevention. In order to prevent inappropriate clinical trials, a potential pharmacological agent should be proved reproducibly effective in clinically relevant experimental studies before initiation of human studies. The closed-chest porcine model is a promising experimental model of ischemia-reperfusion injury. The purpose of this systematic review was to describe the pharmacological treatments evaluated in the closed-chest porcine model and discuss different aspects of the model for future use. The systematic review was performed according to the PRISMA guidelines.

The inflammatory response in myocardial injury, repair, and remodelling

Myocardial infarction triggers an intense inflammatory response that is essential for cardiac repair, but which is also implicated in the pathogenesis of postinfarction remodelling and heart failure. Signals in the infarcted myocardium activate toll-like receptor signalling, while complement activation and generation of reactive oxygen species induce cytokine and chemokine upregulation. Leukocytes recruited to the infarcted area, remove dead cells and matrix debris by phagocytosis, while preparing the area for scar formation. Timely repression of the inflammatory response is critical for effective healing, and is followed by activation of myofibroblasts that secrete matrix proteins in the infarcted area. Members of the transforming growth factor β family are critically involved in suppression of inflammation and activation of a profibrotic programme. Translation of these concepts to the clinic requires an understanding of the pathophysiological complexity and heterogeneity of postinfarction remodelling in patients with myocardial infarction. Individuals with an overactive and prolonged postinfarction inflammatory response might exhibit left ventricular dilatation and systolic dysfunction and might benefit from targeted anti-IL-1 or anti-chemokine therapies, whereas patients with an exaggerated fibrogenic reaction can develop heart failure with preserved ejection fraction and might require inhibition of the Smad3 (mothers against decapentaplegic homolog 3) cascade. Biomarker-based approaches are needed to identify patients with distinct pathophysiologic responses and to rationally implement inflammation-modulating strategies.

Complement factor concentrations in patients with acute myocardial infarction: time course and ability to predict left ventricular dysfunction

Aim: Inflammatory processes may contribute to myocardial ischemia/reperfusion injury after myocardial infarction (MI). We aimed to evaluate the predictive value of complement factor concentrations for the occurrence of post-MI left ventricular (LV) dysfunction. Patients & methods: Fifty-five patients with acute MI were included. Complement factors and CRP were assessed at hospital admission (HA) and during the first 3 days. LV ejection fraction was determined by echocardiography before hospital discharge. Results: Total hemolytic complement (CH50) on admission and peak CRP during the first hospitalization days were higher in patients who developed LV dysfunction (LV ejection fraction ≤45%). By contrast, neither absolute concentrations of single complement factor concentrations nor changes in these concentrations over time were associated with the occurrence of LV dysfunction. CH50 at HA was independently associated with LV dysfunction. Conclusion: This study generates the hypothesis that CH50 concentration at HA in patients with acute MI may identify individuals at high risk for LV dysfunction.

Prognostic value of culprit site neutrophils in acute coronary syndrome

BACKGROUND

Recent data suggest that acute coronary syndromes (ACS) and acute myocardial infarction (AMI) are characterized by an inflammatory subset of thrombosis. We have previously described the accumulation of neutrophils at the coronary culprit lesion site. In this work, we assessed the prognostic value of culprit site (CS) neutrophil accumulation on long-term mortality in patients with AMI.

MATERIALS AND METHODS

In this prospective study, 417 AMI patients were enrolled after thrombectomy during primary percutaneous coronary intervention. The optimal cut-off for CS neutrophil accumulation for predicting 4-year all-cause mortality was calculated using time-dependent receiver operator characteristic curve analyses.

RESULTS

The median follow-up time was 39 months interquartile range (IQR 21·4-54·6 months) corresponding to 1217 patient years of follow-up. The cut-off for CS neutrophil accumulation (difference between culprit neutrophil counts and systemic neutrophil counts) was 0·25 Giga/l. CS neutrophil accumulation occurred in 195 patients (47%) and was independently associated with mortality (hazard ratio 1·88 (95%CI 1·02-3·41, P = 0·043)). In patients with CS neutrophil accumulation, 1-year mortality (10·8% vs. 7·2%) and 4-year mortality (19·8% vs. 10·4%) were markedly increased compared with patients without local neutrophil accumulation. Concordance index for CS neutrophil accumulation and mortality was 0·64 (95% CI 0·51-0·77; P = 0·035). Patients with CS neutrophil accumulation had significantly more often nonobstructive lesions compared with patients without neutrophil accumulation (32·6% vs. 22·4%; P = 0·024).

CONCLUSIONS

Neutrophil accumulation at the coronary culprit lesion site is a strong and independent predictor of mortality in patients with ACS/AMI.

Prognostic implications of left ventricular end-diastolic pressure during primary percutaneous coronary intervention for ST-segment elevation myocardial infarction: Findings from the Assessment of Pexelizumab in Acute Myocardial Infarction study

BACKGROUND

Left ventricular end-diastolic pressure (LVEDP) is frequently measured during primary percutaneous coronary intervention (PCI). However, little is known of this measurement's utility in predicting outcomes or informing treatment decisions. We sought to determine the prognostic value of LVEDP measured during primary PCI for ST-segment elevation myocardial infarction (STEMI).

METHODS

We studied 1,909 (33.2%) of 5,745 STEMI patients in whom LVEDP was measured during primary PCI in the APEX-AMI trial. Cox regression analysis was used to evaluate whether LVEDP was an independent predictor of mortality and the composite of death, cardiogenic shock, or congestive heart failure (CHF) at 90 days.

RESULTS

The median (25th, 75th percentiles) LVEDP level was 22 mm Hg (16, 29); compared with patients with LVEDP ≤ 22 mm Hg, those with LVEDP > 22 mm Hg had higher rates of CHF (7.3% vs 3.1%, P < .001), cardiogenic shock (4.6% vs 1.7%, P < .001), and death (4.1% vs 2.2%, P = .014) at 90 days. After multivariable adjustment, LVEDP was associated with increased risk of mortality through 90 days (adjusted hazard ratio 1.22, 95% CI 1.02-1.46, per 5-mmHg increase, P = .044) and the composite of death, cardiogenic shock, or CHF within the first 2 days (adjusted hazard ratio 1.40, 95% CI 1.23-1.59, per 5-mm Hg increase, P < .001), but not from day 3 to 90 (P = .25).

CONCLUSIONS

Left ventricular end-diastolic pressure measured during primary PCI for STEMI is an independent predictor of inhospital and longer term cardiovascular outcomes. Measuring LVEDP may be useful to stratify patient risk and guide postinfarct treatment.

B lymphocytes trigger monocyte mobilization and impair heart function after acute myocardial infarction

Acute myocardial infarction is a severe ischemic disease responsible for heart failure and sudden death. Here, we show that after acute myocardial infarction in mice, mature B lymphocytes selectively produce Ccl7 and induce Ly6C(hi) monocyte mobilization and recruitment to the heart, leading to enhanced tissue injury and deterioration of myocardial function. Genetic (Baff receptor deficiency) or antibody-mediated (CD20- or Baff-specific antibody) depletion of mature B lymphocytes impeded Ccl7 production and monocyte mobilization, limited myocardial injury and improved heart function. These effects were recapitulated in mice with B cell-selective Ccl7 deficiency. We also show that high circulating concentrations of CCL7 and BAFF in patients with acute myocardial infarction predict increased risk of death or recurrent myocardial infarction. This work identifies a crucial interaction between mature B lymphocytes and monocytes after acute myocardial ischemia and identifies new therapeutic targets for acute myocardial infarction.

Acute myocardial infarction and thyroid function: new pathophysiological and therapeutic perspectives

In the post-reperfusion era, molecular and genetic mechanisms of cardioprotection and regeneration represent new therapeutic challenges to limit infarct size and minimize post-ischemic remodeling after acute myocardial infarction (AMI). Activation of cell survival mechanisms can be promoted by the administration of external drugs, stimulation of internal mechanisms, and genetic manipulation to delete or replace pathological genes or enhance gene expression. Among internal cardiovascular regulatory mechanisms, thyroid hormones (THs) may play a fundamental role. TH has a critical role in cardiovascular development and homeostasis in both physiological and pathological conditions. In experimental AMI, TH has been shown to affect cardiac contractility, left ventricular (LV) function, and remodeling. Several experimental studies have clearly shown that THs participate in the regulation of molecular mechanisms of angiogenesis, cardioprotection, cardiac metabolism, and ultimately myocyte regeneration, changes that can reverse left ventricular remodeling by favorably improving myocyte shape and geometry of LV cavity, thus improving systolic and diastolic performance. This review is focused on the role of thyroid on AMI evolution and on the potential novel option of thyroid-related treatment of AMI.

Final tips in interpreting evidence-based medicine

In this issue, the Southern Medical Journal presents a series of articles to help students of medicine understand the principles of evidence-based medicine. These articles are not meant to be a comprehensive review, but rather an easy-to-read primer. In this final article, the authors offer suggestions to aid the reader in navigating the ever-expanding amount of information. These tips address a number of points that are commonly encountered in the medical literature, but are not all-inclusive.

Role of complement and perspectives for intervention in ischemia-reperfusion damage

Reperfusion of an organ following prolonged ischemia instigates the pro-inflammatory and pro-coagulant response of ischemia / reperfusion (IR) injury. IR injury is a wide-spread pathology, observed in many clinically relevant situations, including myocardial infarction, stroke, organ transplantation, sepsis and shock, and cardiovascular surgery on cardiopulmonary bypass. Activation of the classical, alternative, and lectin complement pathways and the generation of the anaphylatoxins C3a and C5a lead to recruitment of polymorphonuclear leukocytes, generation of radical oxygen species, up-regulation of adhesion molecules on the endothelium and platelets, and induction of cytokine release. Generalized or pathway-specific complement inhibition using protein-based drugs or low-molecular-weight inhibitors has been shown to significantly reduce tissue injury and improve outcome in numerous in-vitro, ex-vivo, and in-vivo models. Despite the obvious benefits in experimental research, only few complement inhibitors, including C1-esterase inhibitor, anti-C5 antibody, and soluble complement receptor 1, have made it into clinical trials of IR injury. The results are mixed, and the next objectives should be to combine knowledge and experience obtained in the past from animal models and channel future work to translate this into clinical trials in surgical and interventional reperfusion therapy as well as organ transplantation.

Ischemia and reperfusion--from mechanism to translation

Ischemia and reperfusion-elicited tissue injury contributes to morbidity and mortality in a wide range of pathologies, including myocardial infarction, ischemic stroke, acute kidney injury, trauma, circulatory arrest, sickle cell disease and sleep apnea. Ischemia-reperfusion injury is also a major challenge during organ transplantation and cardiothoracic, vascular and general surgery. An imbalance in metabolic supply and demand within the ischemic organ results in profound tissue hypoxia and microvascular dysfunction. Subsequent reperfusion further enhances the activation of innate and adaptive immune responses and cell death programs. Recent advances in understanding the molecular and immunological consequences of ischemia and reperfusion may lead to innovative therapeutic strategies for treating patients with ischemia and reperfusion-associated tissue inflammation and organ dysfunction.

Complement component 5 contributes to poor disease outcome in humans and mice with pneumococcal meningitis

Pneumococcal meningitis is the most common and severe form of bacterial meningitis. Fatality rates are substantial, and long-term sequelae develop in about half of survivors. Disease outcome has been related to the severity of the proinflammatory response in the subarachnoid space. The complement system, which mediates key inflammatory processes, has been implicated as a modulator of pneumococcal meningitis disease severity in animal studies. Additionally, SNPs in genes encoding complement pathway proteins have been linked to susceptibility to pneumococcal infection, although no associations with disease severity or outcome have been established. Here, we have performed a robust prospective nationwide genetic association study in patients with bacterial meningitis and found that a common nonsynonymous complement component 5 (C5) SNP (rs17611) is associated with unfavorable disease outcome. C5 fragment levels in cerebrospinal fluid (CSF) of patients with bacterial meningitis correlated with several clinical indicators of poor prognosis. Consistent with these human data, C5a receptor-deficient mice with pneumococcal meningitis had lower CSF wbc counts and decreased brain damage compared with WT mice. Adjuvant treatment with C5-specific monoclonal antibodies prevented death in all mice with pneumococcal meningitis. Thus, our results suggest C5-specific monoclonal antibodies could be a promising new antiinflammatory adjuvant therapy for pneumococcal meningitis.

Apixaban with antiplatelet therapy after acute coronary syndrome

BACKGROUND

Apixaban, an oral, direct factor Xa inhibitor, may reduce the risk of recurrent ischemic events when added to antiplatelet therapy after an acute coronary syndrome.

METHODS

We conducted a randomized, double-blind, placebo-controlled clinical trial comparing apixaban, at a dose of 5 mg twice daily, with placebo, in addition to standard antiplatelet therapy, in patients with a recent acute coronary syndrome and at least two additional risk factors for recurrent ischemic events.

RESULTS

The trial was terminated prematurely after recruitment of 7392 patients because of an increase in major bleeding events with apixaban in the absence of a counterbalancing reduction in recurrent ischemic events. With a median follow-up of 241 days, the primary outcome of cardiovascular death, myocardial infarction, or ischemic stroke occurred in 279 of the 3705 patients (7.5%) assigned to apixaban (13.2 events per 100 patient-years) and in 293 of the 3687 patients (7.9%) assigned to placebo (14.0 events per 100 patient-years) (hazard ratio with apixaban, 0.95; 95% confidence interval [CI], 0.80 to 1.11; P=0.51). The primary safety outcome of major bleeding according to the Thrombolysis in Myocardial Infarction (TIMI) definition occurred in 46 of the 3673 patients (1.3%) who received at least one dose of apixaban (2.4 events per 100 patient-years) and in 18 of the 3642 patients (0.5%) who received at least one dose of placebo (0.9 events per 100 patient-years) (hazard ratio with apixaban, 2.59; 95% CI, 1.50 to 4.46; P=0.001). A greater number of intracranial and fatal bleeding events occurred with apixaban than with placebo.

CONCLUSIONS

The addition of apixaban, at a dose of 5 mg twice daily, to antiplatelet therapy in high-risk patients after an acute coronary syndrome increased the number of major bleeding events without a significant reduction in recurrent ischemic events. (Funded by Bristol-Myers Squibb and Pfizer; APPRAISE-2 ClinicalTrials.gov number, NCT00831441.).

Cardioprotection in the clinical setting-lessons from J-WIND studies

INTRODUCTION

Both prevention and attenuation of ischemic heart disease are important issues, and there are three different strategies to save patients from the deleterious sequelae of ischemic injury. The first strategy is to remove the causes of ischemic heart disease; the second is to attenuate on-going ischemic and reperfusion injury; the third is to prevent the progression of cardiac remodeling and chronic heart failure following ischemic injury.

EVIDENCE AND DISCUSSION

For prevention of acute myocardial infarction, it is widely accepted to treat high risk patients with aspirin and/or statins. On the other hand, several medications such as angiotensin converting enzyme inhibitors, aldosterone receptor antagonists and beta blockers have been used for the prevention of post-infarction heart failure in patients who have suffered from an acute myocardial infarction. However, at present we do not have an adjunctive drug therapy to reduce infarct size in the acute phase in patients with myocardial infarction. Recently, the J-WIND trials suggested that an infusion of human atrial natriuretic peptide in the acute phase and oral administration of nicorandil in the chronic phase of infarction result in a better outcome in patients with a myocardial infarction. In this article we propose potential mechanisms for cardioprotection in patients with an acute myocardial infarction.

Treatment with the C5a receptor antagonist ADC-1004 reduces myocardial infarction in a porcine ischemia-reperfusion model

BACKGROUND

Polymorphonuclear neutrophils, stimulated by the activated complement factor C5a, have been implicated in cardiac ischemia/reperfusion injury. ADC-1004 is a competitive C5a receptor antagonist that has been shown to inhibit complement related neutrophil activation. ADC-1004 shields the neutrophils from C5a activation before they enter the reperfused area, which could be a mechanistic advantage compared to previous C5a directed reperfusion therapies. We investigated if treatment with ADC-1004, according to a clinically applicable protocol, would reduce infarct size and microvascular obstruction in a large animal myocardial infarct model.

METHODS

In anesthetized pigs (42-53 kg), a percutaneous coronary intervention balloon was inflated in the left anterior descending artery for 40 minutes, followed by 4 hours of reperfusion. Twenty minutes after balloon inflation the pigs were randomized to an intravenous bolus administration of ADC-1004 (175 mg, n = 8) or saline (9 mg/ml, n = 8). Area at risk (AAR) was evaluated by ex vivo SPECT. Infarct size and microvascular obstruction were evaluated by ex vivo MRI. The observers were blinded to the treatment at randomization and analysis.

RESULTS

ADC-1004 treatment reduced infarct size by 21% (ADC-1004: 58.3 ± 3.4 vs control: 74.1 ± 2.9%AAR, p = 0.007). Microvascular obstruction was similar between the groups (ADC-1004: 2.2 ± 1.2 vs control: 5.3 ± 2.5%AAR, p = 0.23). The mean plasma concentration of ADC-1004 was 83 ± 8 nM at sacrifice. There were no significant differences between the groups with respect to heart rate, mean arterial pressure, cardiac output and blood-gas data.

CONCLUSIONS

ADC-1004 treatment reduces myocardial ischemia-reperfusion injury and represents a novel treatment strategy of myocardial infarct with potential clinical applicability.

Predicting the no-reflow phenomenon following successful percutaneous coronary intervention

In the setting of acute myocardial infarction, early and adequate reopening of an infarct-related artery is not necessarily followed by a complete restoration of myocardial perfusion. This condition is usually defined as ‘no-reflow’. The pathophysiology of no-reflow is multifactorial since extravascular compression, microvascular vasoconstriction, embolization during percutaneous coronary intervention, and platelet and neutrophil aggregates are involved. In the clinical arena, angiographic findings and easily available clinical parameters can predict the risk of no-reflow. More recently, several studies have demonstrated that biomarkers, especially those related to the pathogenetic components of no-reflow, could also have a prognostic role in the prediction and in the full understanding of the multiple mechanisms of this phenomenon. Thus, in this article, we investigate the role of several biomarkers on admission in predicting the occurrence of no-reflow following successful percutaneous coronary intervention.

Stem cell therapy for chronic myocardial infarction

Although recent advances for the treatment of myocardial infarction have dramatically increased the rate of survival after the ischemic event, this has also led to a rise in the number of chronic patients, making the finding of a suitable therapy a compulsory subject for modern medicine. Over the last decade, stem cells have been a promise for the cure of several diseases not only due to their plasticity but also to their capacity to act in a paracrine manner and influence the affected tissue, prompting the launching of several clinical trials. In spite of the knowledge already acquired, stem cell application to chronically infarcted hearts has been much less approached than its acute counterpart. Through this review, we will focus in stem cell therapy in animal models of chronic myocardial infarction: cell types employed, functional results, mechanisms analyzed, and questions raised.

The inflammatory response and cardiac repair after myocardial infarction

One of the most important therapeutic targets of current cardiology practice is to determine optimal strategies for the minimization of myocardial necrosis and optimization of cardiac repair following an acute myocardial infarction. Myocardial necrosis after acute myocardial infarction induces complement activation and free radical generation, triggering a cytokine cascade initiated by tumor necrosis factor-alpha (TNF-α) release. When reperfusion of the infarcted area is initiated, intense inflammation follows. Chemokines, cytokines and the complement system play an important role in recruiting neutrophils in the ischemic and reperfused myocardium. Cytokines promote adhesive interactions between leukocytes and endothelial cells, resulting in transmigration of inflammatory cells into the site of injury. The recruited neutrophils have potent cytotoxic effects through the release of proteolytic enzymes, and they interact with adhesion molecules on cardiomyocytes. In spite of the potential injury, reperfusion enhances cardiac repair; this may be related to the inflammatory response. Monocyte chemoattractant protein (MCP)-1 is upregulated in reperfused myocardium and can induce monocyte recruitment in the infarcted area. Monocyte subsets play a role in phagocytosis of dead cardiomyocytes and in granulation tissue formation. In addition, the transforming growth factor (TGF)-β plays a crucial role in cardiac repair by suppressing inflammation. Resolution of inflammatory infiltration, containment of inflammation and the reparative response affecting the infarcted area are essential for optimal infarct healing. Here, we review the current literature on the inflammatory response and cardiac repair after myocardial infarction.

Complement-mediated ischemia-reperfusion injury: lessons learned from animal and clinical studies

Ischemia-reperfusion (I/R) injury provides a substantial limitation to further improvements in the development of therapeutic strategies for ischemia-related diseases. Studies in animal I/R models, including intestinal, hindlimb, kidney, and myocardial I/R models, have established a key role of the complement system in mediation of I/R injury using complement inhibitors and knock-out animal models. As complement activation has been shown to be an early event in I/R injury, inhibiting its activation or its components may offer tissue protection after reperfusion. However, clinical study results using complement inhibitors have largely been disappointing. Therefore, identification of a more specific pathogenic target for therapeutic intervention seems to be warranted. For this purpose more detailed knowledge of the responsible pathway of complement activation in I/R injury is required. Recent evidence from in vitro and in vivo models suggests involvement of both the classic and the lectin pathways in I/R injury via exposition of neo-epitopes in ischemic membranes. However, most of these findings have been obtained in knock-out murine models and have for a large part remained unconfirmed in the human setting. The observation that the relative role of each pathway seems to differ among organs complicates matters further. Whether a defective complement system protects from I/R injury in humans remains largely unknown. Most importantly, involvement of mannose-binding lectin as the main initiator of the lectin pathway has not been demonstrated at tissue level in human I/R injury to date. Thus, conclusions drawn from animal I/R studies should be extrapolated to the human setting with caution.

From randomized trials to registry studies: translating data into clinical information

All clinicians face the challenge of practicing evidence-based medicine and are confronted with data from a variety of studies, ranging from prospective randomized and registry studies to retrospective analyses. Unfortunately, the data frequently provide conflicting recommendations. How then should one interpret the information so that study findings can be applied directly in patient care? To evaluate the relevance of the abundance of studies published and how they apply to an individual patient, physicians must understand subtle nuances of study design and their effect on the interpretation of the results. In this Review, we examine the strengths and weaknesses of different study designs with the aim of providing the reader with a greater understanding how best to apply study results in the clinical setting.

Bivalirudin during primary PCI in acute myocardial infarction

BACKGROUND

Treatment with the direct thrombin inhibitor bivalirudin, as compared with heparin plus glycoprotein IIb/IIIa inhibitors, results in similar suppression of ischemia while reducing hemorrhagic complications in patients with stable angina and non-ST-segment elevation acute coronary syndromes who are undergoing percutaneous coronary intervention (PCI). The safety and efficacy of bivalirudin in high-risk patients are unknown.

METHODS

We randomly assigned 3602 patients with ST-segment elevation myocardial infarction who presented within 12 hours after the onset of symptoms and who were undergoing primary PCI to treatment with heparin plus a glycoprotein IIb/IIIa inhibitor or to treatment with bivalirudin alone. The two primary end points of the study were major bleeding and combined adverse clinical events, defined as the combination of major bleeding or major adverse cardiovascular events, including death, reinfarction, target-vessel revascularization for ischemia, and stroke (hereinafter referred to as net adverse clinical events) within 30 days.

RESULTS

Anticoagulation with bivalirudin alone, as compared with heparin plus glycoprotein IIb/IIIa inhibitors, resulted in a reduced 30-day rate of net adverse clinical events (9.2% vs. 12.1%; relative risk, 0.76; 95% confidence interval [CI] 0.63 to 0.92; P=0.005), owing to a lower rate of major bleeding (4.9% vs. 8.3%; relative risk, 0.60; 95% CI, 0.46 to 0.77; P<0.001). There was an increased risk of acute stent thrombosis within 24 hours in the bivalirudin group, but no significant increase was present by 30 days. Treatment with bivalirudin alone, as compared with heparin plus glycoprotein IIb/IIIa inhibitors, resulted in significantly lower 30-day rates of death from cardiac causes (1.8% vs. 2.9%; relative risk, 0.62; 95% CI, 0.40 to 0.95; P=0.03) and death from all causes (2.1% vs. 3.1%; relative risk, 0.66; 95% CI, 0.44 to 1.00; P=0.047).

CONCLUSIONS

In patients with ST-segment elevation myocardial infarction who are undergoing primary PCI, anticoagulation with bivalirudin alone, as compared with heparin plus glycoprotein IIb/IIIa inhibitors, results in significantly reduced 30-day rates of major bleeding and net adverse clinical events. (ClinicalTrials.gov number, NCT00433966 [ClinicalTrials.gov].).

Discovery and development of the complement inhibitor eculizumab for the treatment of paroxysmal nocturnal hemoglobinuria

The complement system provides critical immunoprotective and immunoregulatory functions but uncontrolled complement activation can lead to severe pathology. In the rare hemolytic disease paroxysmal nocturnal hemoglobinuria (PNH), somatic mutations result in a deficiency of glycosylphosphatidylinositol-linked surface proteins, including the terminal complement inhibitor CD59, on hematopoietic stem cells. In a dysfunctional bone marrow background, these mutated progenitor blood cells expand and populate the periphery. Deficiency of CD59 on PNH red blood cells results in chronic complement-mediated intravascular hemolysis, a process central to the morbidity and mortality of PNH. A recently developed, humanized monoclonal antibody directed against complement component C5, eculizumab (Soliris; Alexion Pharmaceuticals Inc., Cheshire, CT, USA), blocks the proinflammatory and cytolytic effects of terminal complement activation. The recent approval of eculizumab as a first-in-class complement inhibitor for the treatment of PNH validates the concept of complement inhibition as an effective therapy and provides rationale for investigation of other indications in which complement plays a role.

Anti-inflammatory drugs and atherosclerosis

PURPOSE OF REVIEW

Inflammation contributes to the formation and progression of atherosclerosis and the therapeutic potential of some anti-inflammatory drugs has been evaluated for possible antiatherosclerotic effects. This review will briefly describe the mechanisms underlying the inflammation-atherosclerosis connection, the effect of various anti-inflammatory therapies on atherosclerotic disease and a sampling of the potential targets and agents under evaluation.

RECENT FINDINGS

Some agents with anti-inflammatory properties appear to have beneficial effects on atherosclerosis or subsequent risk for cardiovascular events, while others have been disappointing. The anti-inflammatory actions of statins have been linked retrospectively with their favorable effects on atherosclerosis progression and clinical outcomes. The cardiovascular safety of COX-2 inhibitors is being assessed prospectively in patients with atherosclerosis. Potential new therapeutic agents targeting other inflammatory mechanisms and oxidative stress are being evaluated in animal models and clinical trials.

SUMMARY

Due to the contributory inflammatory pathways in atherosclerosis, the properties of existing and novel anti-inflammatory agents are being carefully and actively evaluated in cardiovascular disease. Advances in our understanding of both atherosclerosis and the inflammatory contributors may play an important role in future strategies to decrease the incidence of atherosclerotic cardiovascular disease.

Complement-targeted therapeutics

The complement system is a central component of innate immunity and bridges the innate to the adaptive immune response. However, it can also turn its destructive capabilities against host cells and is involved in numerous diseases and pathological conditions. Modulation of the complement system has been recognized as a promising strategy in drug discovery, and a large number of therapeutic modalities have been developed. However, successful marketing of complement-targeted drugs has proved to be more difficult than initially expected, and many strategies have been discontinued. The US Food and Drug Administration's approval of the first complement-specific drug, an antibody against complement component C5 (eculizumab; Soliris), in March 2007, was a long-awaited breakthrough in the field. Approval of eculizumab validates the complement system as therapeutic target and might facilitate clinical development of other promising drug candidates.

Natural IgM-mediated innate autoimmunity: a new target for early intervention of ischemia-reperfusion injury

Recent studies showed that innate autoimmunity is an early mechanism for ischemia-reperfusion (I/R) injury. Results from different animal models showed that reperfusion of ischemic tissues elicits an acute inflammatory response involving a complement system, which is activated by autoreactive natural IgM. Moreover, ischemia-specific self-targets were identified. In contrast to the unsuccessful attempts in the past to treat I/R injury, targeting natural IgM-mediated innate autoimmunity may open a new avenue for early intervention.