Inflammatory and vasoactive factors in the aspirate from the culprit coronary artery of patients with acute myocardial infarction

Platelets in Myocardial Ischemia/Reperfusion Injury

Coronary artery disease, including myocardial infarction (MI), remains a leading cause of global mortality. Rapid reperfusion therapy is key to the improvement of patient outcome but contributes substantially to the final cardiac damage. This phenomenon is called "ischemia/reperfusion injury (IRI)." The underlying mechanisms of IRI are complex and not fully understood. Contributing cellular and molecular mechanisms involve the formation of microthrombi, alterations in ion concentrations, pH shifts, dysregulation of osmolality, and, importantly, inflammation. Beyond their known action as drivers of the development of coronary plaques leading to MI, platelets have been identified as important mediators in myocardial IRI. Circulating platelets are activated by the IRI-provoked damages in the vascular endothelium. This leads to platelet adherence to the reperfused endothelium, aggregation, and the formation of microthrombi. Furthermore, activated platelets release vasoconstrictive substances, act via surface molecules, and enhance leukocyte infiltration into post-IR tissue, that is, via platelet-leukocyte complexes. A better understanding of platelet contributions to myocardial IRI, including their interaction with other lesion-associated cells, is necessary to develop effective treatment strategies to prevent IRI and further improve the condition of the reperfused myocardium. In this review, we briefly summarize platelet properties that modulate IRI. We also describe the beneficial impacts of antiplatelet agents as well as their mechanisms of action in IRI beyond classic effects.

Renal allograft-related inflammation complicated by acute coronary syndromes: A case report

INTRODUCTION

Persistent systemic inflammation is considered to be predictive for future cardiovascular events. Here, in a patient with pyelonephritis of his failed renal allograft, consecutive coronary angiograms proved that coronary artery disease progressed within 3 weeks, when infection was uncontrolled.

PATIENT CONCERNS

A 52-year-old male type 2 diabetic with a failed renal allograft suffering from hematuria, leukocyturia, and chest pain at rest was hospitalized.

DIAGNOSES

An acute coronary syndrome in presence of pyelonephritis was diagnosed. Besides pyelonephritis, the histological examination of the kidney transplant revealed signs of chronic rejection and the presence of a renal cell carcinoma in situ.

INTERVENTIONS

A percutaneous coronary intervention was performed, and an elective surgery for allograft removal was scheduled. However, within 5 weeks after discharge, two more surges of infection coincided with episodes of unstable angina.

OUTCOMES

Once the renal allograft has been removed, systemic inflammation was contained. The patient was not re-hospitalized for acute-coronary syndrome within the next 12 months.

CONCLUSION

Surges of systemic inflammation due to infection were paralleled by instability of coronary plaques as documented by repeat coronary angiograms.

Changes in serum serotonin levels in patients with acute coronary syndrome and stable angina undergoing percutaneous coronary intervention

OBJECTIVE

Activated platelets release serotonin, causing platelet aggregation and vasoconstriction. Serotonin levels were investigated in patients with acute coronary syndrome (ACS) and chronic stable angina (CSA) treated with percutaneous coronary intervention (PCI).

METHODS

Consecutive patients undergoing PCI for either ACS or CSA were enrolled between July 2009 and April 2010. Patients were pre-treated with dual antiplatelet agents (aspirin and clopidogrel) before PCI. Serum serotonin levels, measured at baseline, pre- and post-PCI, and at 90 min, and 6, 12, 24 and 48 h following PCI, were compared between ACS and CSA groups.

RESULTS

Sixty-three patients with ACS and 60 with CSA were included. Overall baseline characteristics were similar between the two groups. Serotonin levels at post-PCI (55.2 ± 120.0 versus 20.1 ± 24.0) and at peak (regardless of timepoint; 94.0 ± 170.9 versus 38.8 ± 72.3) were significantly higher in the ACS versus CSA group. At 90 min and 6, 24 and 48 h post-PCI, serum serotonin was numerically, but not significantly, higher in patients with ACS. Serotonin levels fluctuated in both groups, showing an initial rise and fall, rebound at 24 h and drop at 48 h post-PCI.

CONCLUSIONS

In patients undergoing PCI, serum serotonin was more elevated in patients with ACS than those with CSA, suggesting the need for more potent and sustained platelet inhibition, particularly in patients with ACS.

Novel insights in the relationship of gut microbiota and coronary artery diseases

Atherosclerosis is a chronic, progressive, inflammatory disease in the vasculature and is common in both coronary and peripheral arteries. Human beings harbor a complex and dynamic population of microorganisms defined as the microbiota. Importantly, alterations in the bacterial composition (dysbiosis) and the metabolic compounds produced by these bacteria have been associated with the pathogenesis of many inflammatory diseases and infections. There is also a close relationship between intestinal microbiota and cardiovascular diseases. The aim of this review was to analyze how changes in the gut microbiota and their metabolites might affect coronary artery diseases. The most representative groups of bacteria that make up the intestinal microbiota are altered in coronary artery disease patients, resulting in a decrease in Bacteroidetes and an increase in Firmicutes. In relation to metabolites, trimethylamine-N-oxide plays an important role in atherosclerosis and may act as a cardiovascular risk predictor. In addition, the use of probiotics, prebiotics, diet modulation, and fecal transplantation, which may represent alternative treatments for these diseases, is thoroughly discussed. Finally, the role of lipid-lowering treatments is also analyzed as they may affect and alter the gut microbiota and, conversely, gut microbiota diversity could be associated with resistance or sensitivity to these treatments.

Evaluation of Serum Serotonin as a Biomarker for Myocardial Infarction and Ischemia/Reperfusion Injury

Background: Activated platelets release serotonin during acute myocardial infarction (AMI), aggravating myocardial damage and ischemia/reperfusion (I/R) injury. However, serum serotonin and its potential role as a biomarker for myocardial infarction and I/R injury have not been studied so far. Methods: In this investigator-initiated pilot study, we examined 38 patients with ST-segment myocardial infarction (STEMI). We determined serum serotonin levels prior to percutaneous coronary intervention and 8, 16, and 24 h afterwards. We studied whether serum serotonin was associated with I/R injury assessed by ECG analysis and by analysis of TIMI myocardial perfusion grade (TMP) and myocardial blush grade (MGB). Serum serotonin levels were compared to an age-matched control group consisting of patients admitted to the emergency department for any other reason than STEMI. Results: Serum serotonin levels were not elevated in the myocardial infarction group compared to the control cohort and they did not show any timeline kinetics after STEMI. They were not associated with the severity of coronary artery disease, the outcome of coronary angiography, the extent of I/R injury, or the degree of heart failure. Conclusions: Serum serotonin is not suitable as a biomarker after myocardial infarction and in the assessment of I/R injury.

High-molecular-weight kininogen and the intrinsic coagulation pathway in patients with de novo acute myocardial infarction

After an acute ischaemic event serum proteins may change reflecting the ischaemic damage. Proteomic studies could provide new insights into potential biomarkers in the evolution of ischaemic syndromes. In this study we have investigated the coordinated changes in coagulation-related proteins in the evolution after an acute myocardial infarction (AMI). Serum proteome (2D-electrophoresis and MALDI-TOF/ TOF) of AMI-patients within the first 6 hours after event onset (admission-time) and 3 days after were compared to controls. Systems biology and bioinformatic analysis were performed to identify the differentially expressed canonical pathways. In silico analysis of differential proteins revealed changes in the intrinsic coagulation pathway in the early phase post-AMI. The two identified high-molecular weight kininogen (HMWK) clusters were inversely correlated in AMI patients at admission, being the intensity of the low-molecular-weight form inversely related to myocardial necrosis (p<0.05). Factor XI (FXI) levels were decreased in AMI patients at admission and normalised 3 days after (p<0.05). There was an early increase in fibrinogen gamma and D-dimer at admission, followed by a decrease in fibrinogen turnover 3 days after (p<0.05). The influence of elapsed time of ischaemia on fibrinogen distribution changes was validated in coronary thrombi retrieved by thromboaspiration. In conclusion, our results demonstrate an active exchange between HMWK forms and a decrease in FXI indicative of intrinsic pathway activation, together with an increase in fibrinogen gamma turnover and D-dimer formation in the early phase post-AMI. Moreover, coronary thrombi showed a dynamic evolution in fibrinogen composition depending on the duration of ischaemia influencing serum fibrinogen-related products content.

Early inflammatory cytokine response: a direct comparison between spontaneous coronary plaque destabilization vs angioplasty induced

AIM

To compare inflammatory response accompanying acute coronary syndrome (ACS) with that following coronary plaque rupture caused by coronary angioplasty (PCI).

METHODS

Twenty-seven consecutive subjects with either ACS or treated with PCI in the subacute phase of ACS underwent serial evaluation of circulating interleukin (IL)-2, IL-8, IL-10, interferon (IFN)-γ and tumor-necrosis-factor (TNF)-α levels. Blood samples were drawn immediately before angioplasty (T0) in the PCI group or at admission in the ACS group, 12 h (T1) and 24 h later (T2).

RESULTS

Differences between cytokine levels were substantially not statistically significant when comparing PCI, non-ST-elevation-ACS, and ST-elevation-ACS groups, especially 24 h after plaque rupture (T2, Type-II error 85-94%).

CONCLUSIONS

Inflammatory activation during the first 24 h of ACS or after PCI is comparable, regardless of myocardial damage in terms of troponin levels. Coronary plaque rupture may be presumed as being the main responsible for increased circulating cytokine levels in this early phase.

Serum albumin levels on admission are associated with angiographic no-reflow after primary percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction

Low serum albumin (SA) levels are associated with increased cardiovascular mortality. We investigated whether baseline SA levels are associated with no-reflow following primary percutaneous coronary intervention (pPCI). A total of 536 patients (aged 60 ± 13 years; 74% men) who underwent pPCI were enrolled. The patients were divided into 2 groups: no-reflow and normal-reflow. No-reflow was defined as thrombolysis in myocardial infarction ≤2 flow. Admission SA levels were significantly lower in the no-reflow group than in the normal-reflow group (3.55 ± 0.44 vs 4.01 ± 0.32 mg/dL, P < .001). Also, high-sensitivity C-reactive protein (hsCRP), creatinine, creatine kinase myocardial band isoenzyme, and troponin T were significantly higher while hemoglobin and left ventricular ejection fraction (LVEF) were significantly lower in the no-reflow group. In multivariate analysis, SA level remained an independent predictor of angiographic no-reflow (odds ratio 0.114, 95% confidence interval 0.032-0.405, P = .001) together with LVEF, hsCRP, and baseline culprit artery patency. Admission SA level was an independent predictor of no-reflow after pPCI.

Elevated plasma IL-37, IL-18, and IL-18BP concentrations in patients with acute coronary syndrome

OBJECTIVE

More recently, evidence showed that the novel anti-inflammatory cytokine interleukin- (IL-) 37 was expressed in the foam-like cells of atherosclerotic coronary and carotid artery plaques, suggesting that IL-37 is involved in atherosclerosis-related diseases. However, the plasma levels of IL-37 in patients with acute coronary syndrome (ACS, including unstable angina pectoris and acute myocardial infarction) have yet to be investigated.

METHODS

Plasma IL-37, IL-18, and IL-18BP levels were measured in 50 patients with stable angina pectoris (SAP), 75 patients with unstable angina pectoris (UAP), 67 patients with acute myocardial infarction (AMI), and 65 control patients.

RESULTS

The plasma IL-37, IL-18, and IL-18BP levels were significantly increased in ACS patients compared to SAP and control patients. A correlation analysis showed that the plasma biomarker levels were positively correlated with each other and with the levels of C-reactive protein (CRP), N-terminal probrain natriuretic peptide (NT-proBNP), and left ventricular end-diastolic dimension (LVEDD) but negatively correlated with left ventricular ejection fraction (LVEF). Furthermore, the plasma IL-37, IL-18, and IL-18BP had no correlation with the severity of the coronary artery stenosis.

CONCLUSIONS

The results indicate that the plasma IL-37 levels are associated with the onset of ACS.

Effects of weight loss on epicardial adipose tissue thickness and its relationship between serum soluble CD40 ligand levels in obese men

BACKGROUND

Epicardial adipose tissue (EAT) induces activated inflammatory cells secreting cytokines, including soluble CD40 ligand (sCD40L). In turn, the serum sCD40L can trigger inflammatory responses. We examined the reduction of EAT in response to weight loss (WL) and its relationship with alterations in sCD40L in obese men.

METHODS

We prospectively provided dietary education and exercise intervention for 3 months for 32 non-diabetic obese men with metabolic syndrome. Twenty-five age-matched healthy men served as controls. Circulating sCD40L was measured, and EAT thickness (EATt) was determined by magnetic resonance imaging before and after WL.

RESULTS

EATt was increased in the obese individuals, but there were no significant differences in baseline serum sCD40L levels between the 2 groups. Serum concentrations of sCD40L were higher in individuals with high right atrioventricular groove (RAVG)-EATt. EATt was reduced significantly in individuals who completed the weight-loss program. In addition, a positive correlation was shown between changes in sCD40L and RAVG-EATt. Multiple linear regression analysis showed the change in sCD40L to be independently associated with the change in RAVG-EATt.

CONCLUSION

WL can significantly reduce epicardial fat thickness, and the reduced EATt after WL may provide a beneficial reduction in circulating levels of sCD40L in obese males.

Lessons from human coronary aspirate

The interventional implantation of a stent into an atherosclerotic coronary artery is a unique and paradigmatic scenario of plaque rupture in humans. The use of protection devices not only prevents the released plaque particles and the superimposed thrombotic material from being washed and embolized into the coronary microcirculation of the individual patient, but permits also the retrieval and ex vivo analysis of particulate plaque debris and soluble substances. The particulate debris comprises typical cholesterol crystals, foam cells, hyalin material and calcium deposits from the atheroma as well as platelets and coagulation material; soluble substances include vasoconstrictors, such as serotonin and thromboxane, as well as inflammatory mediators, such as TNFα which amplifies vasoconstriction by inducing endothelial dysfunction. The vasoconstriction observed in a bioassay ex vivo correlates to clinical symptoms, angiographic stenosis and plaque burden, as assessed by intravascular ultrasound. The release of TNFα into the aspirate correlates to restenosis. Detailed analysis of the human coronary aspirate may promote a better understanding of the pathophysiology of the vulnerable atherosclerotic plaque and help to better antagonize the microvascular consequences of coronary microembolization, including the no reflow phenomenon. This article is part of a Special Issue entitled "Coronary Blood Flow."

Management of the no-reflow phenomenon

The lack of reperfusion of myocardium after prolonged ischaemia that may occur despite opening of the infarct-related artery is termed "no reflow". No reflow or slow flow occurs in 3-4% of all percutaneous coronary interventions, and is most common after emergency revascularization for acute myocardial infarction. In this setting no reflow is reported to occur in 30% to 40% of interventions when defined by myocardial perfusion techniques such as myocardial contrast echocardiography. No reflow is clinically important as it is independently associated with increased occurrence of malignant arrhythmias, cardiac failure, as well as in-hospital and long-term mortality. Previously the no-reflow phenomenon has been difficult to treat effectively, but recent advances in the understanding of the pathophysiology of no reflow have led to several novel treatment strategies. These include prophylactic use of vasodilator therapies, mechanical devices, ischaemic postconditioning and potent platelet inhibitors. As no reflow is a multifactorial process, a combination of these treatments is more likely to be effective than any of these alone. In this review we discuss the pathophysiology of no reflow and present the numerous recent advances in therapy for this important clinical problem.

Tumor necrosis factor superfamily molecules in acute coronary syndromes

Accumulating evidence suggests that inflammatory pathways play an essential role in all stages of atherogenesis. Inflammatory processes are not only involved in plaque progression, but seem also to play a critical role in plaque rupture. Members of the tumor necrosis factor (TNF) superfamiliy are potent regulators of inflammation and cell survival and consist of 20 ligands that signal through 29 different receptors. Several lines of evidence suggest that TNF-related molecules are involved in the development of acute coronary syndromes (ACS). Most, convincing evidence exists for CD40 ligand-CD40 interaction, but several other members of the TNF superfamily seem also to be involved in this immune-mediated promotion of plaque instability, including LIGHT, receptor activator of nuclear factor κB ligand, and TNF-α. These plaque destabilization pathways involve the bidirectional interaction between platelets and endothelial cells/monocytes, activation of vascular smooth muscle cells, and co-stimulatory effects on T cells, promoting inflammation, thrombus formation, matrix degradation, and apoptosis. TNF-related pathways could contribute to the non-resolving inflammation that characterizes atherosclerosis, representing pathogenic loops that are operating during plaque rupture and the development of ACS. These TNF-related molecules could also represent attractive new targets for therapy in this disorder.

Behavior of coagulation factors and normal inhibitors of coagulation during the acute phase of myocardial infarction

Acute coronary syndromes are characterized by increased endothelial activation. The aim of this study was to investigate the behavior of coagulation factors V, VII, VIII and normal inhibitors antithrombin III and protein C during the acute phase of myocardial infarction. Thirty-six patients (27 men, nine women) and 35 normal individuals were studied during the acute phase of myocardial infarction, in the first 24 h. A group of 35 normal individuals was used as a control group. Blood samples were taken within the first 24 h of the hospital admission. The plasma levels of the coagulation factors were measured by the clot formation method, whereas the normal inhibitors were measured by ELISA. In the acute phase of myocardial infarction significant changes occur in coagulant and fibrinolytic factors. A decrease in plasma levels of factor V, antithrombin III and protein C was found in patients with acute myocardial infarction, compared to control group, whereas an increase in plasma levels of factor VII were observed. This study concludes that acute myocardial infarction causes consumption of fibrinolytic factors, whereas the coagulant factors seem to increase when being activated.

The CD40/CD40 ligand system: linking inflammation with atherothrombosis

The role of CD40/CD40 ligand (CD40L) in atherothrombosis is now widely accepted. However, the exact mechanisms linking the CD40/CD40L system and the soluble form of CD40 ligand (sCD40L) with atherothrombosis are currently a topic of intensive research. CD40L and sCD40L belong to the tumor necrosis factor superfamily, and they are molecules with a dual prothrombotic and proinflammatory role. They are expressed in a variety of tissues such as the immune system (in both B and T cells), the vascular wall, and activated platelets. Soluble CD40L has multiple autocrine, paracrine, and endocrine actions, and it may trigger key mechanisms participating in atherothrombosis. CD40/CD40L may participate in the development of coronary atherosclerosis and the triggering of acute coronary syndromes, while sCD40L seems to have a prognostic role not only in subjects with advanced atherosclerosis but also in the general population. Although conventional cardiovascular medication such as antiplatelet therapy, statins, angiotensin-converting enzyme inhibitors, and many others have been shown to reduce both sCD40L and cardiovascular risk, it is still unclear whether specific treatments targeting the CD40/CD40L system will prove to be beneficial against atherothrombosis in the near future.

Coronary artery embolisation

In the setting of an acute inferior myocardial infarction undergoing primary stent implantation, we could document a macroscopic embolus moving along the right coronary artery. Coronary embolisation is a well known drawback of percutaneous coronary interventions and dedicated devices can be used in order to minimize myocardial damage. Nonetheless, unexpected macroscopic embolisation after the first manual contrast injection through a diagnostic catheter remains a possible complication and may lead to unsatisfactory results when the upstream pharmacological therapy is not appropriate.

The impact of admission C-reactive protein levels on the development of no-reflow phenomenon after primary PCI in patients with acute myocardial infarction: the role of inflammation

The role of admission CRP levels on the prediction of poor myocardial perfusion grades after percutaneous coronary intervention (PCI) in patients with acute myocardial infarction (AMI) has not been clearly elucidated. Dynamic nature of acute coronary syndromes is usually associated with spontaneous ischemia-reperfusion injury in infarct related artery. So we considered that poor myocardial perfusion after primary PCI is not only related to procedural factors and clinical characteristics of the patients but may also be related to microvascular damage starting before coronary intervention. We suggested that CRP mediated complement activation and neutrophil plugging may be the factors contributing to the development of microvascular damage in patients with AMI.