Imaging systemic inflammatory networks in ischemic heart disease

Thrombus leukocytes exhibit more endothelial cell-specific angiogenic markers than peripheral blood leukocytes do in acute coronary syndrome patients, suggesting a possibility of trans-differentiation: a comprehensive database mining study

Background

Current angiogenic therapies for cancers and cardiovascular diseases have not yet achieved expected benefits, which reflects the need for improved understanding of angiogenesis. In this study, we focused on solving the problem of whether tissues have different angiogenic potentials (APs) in physiological conditions and how angiogenesis is regulated in various disease conditions.

Methods

In healthy and diseased human and mouse tissues, we profiled the expression of 163 angiogenic genes, including transcription regulators (TRs), growth factors and receptors (GF/Rs), cytokines and chemokines (C/Cs), and proteases and inhibitors (P/Is). TRs were categorized as inflammatory, homeostatic, and endothelial cell-specific TRs, and C/Cs were categorized as pro-angiogenic, anti-angiogenic, and bi-functional C/Cs.

Results

We made the following findings: (1) the human heart, muscle, eye, pancreas, and lymph node are among the tissues with the highest APs; (2) tissues with high APs have more active angiogenic pathways and angiogenic C/C responses; (3) inflammatory TRs dominate regulation of all angiogenic C/Cs; homeostatic TRs regulate all to a lower extent, while endothelial cell-specific TRs mainly regulate pro-angiogenic and bi-functional C/Cs; (4) tissue AP is positively correlated with the expression of oxygen sensors PHD2 and HIF1B, VEGF pathway gene VEGFB, and stem cell gene SOX2; (5) cancers of the digestive system tend to have increased angiogenesis dominated by endothelial cell-specific pro-angiogenic pathways, while lung cancer and prostate cancer have significantly decreased angiogenesis; and (6) endothelial cell-specific pro-angiogenic pathways are significantly increased in thrombus-derived leukocytes in patients with acute coronary artery disease.

Conclusions

Our results demonstrate that thrombus-derived leukocytes express more endothelial cell-specific angiogenic markers to directly promote angiogenesis after myocardial infarction and that certain solid tumors may be more sensitive to anti-angiogenic therapies than others.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-017-0440-0) contains supplementary material, which is available to authorized users.

Conceptual Foundations of Systems Biology Explaining Complex Cardiac Diseases

Systems biology is an important concept that connects molecular biology and genomics with computing science, mathematics and engineering. An endeavor is made in this paper to associate basic conceptual ideas of systems biology with clinical medicine. Complex cardiac diseases are clinical phenotypes generated by integration of genetic, molecular and environmental factors. Basic concepts of systems biology like network construction, modular thinking, biological constraints (downward biological direction) and emergence (upward biological direction) could be applied to clinical medicine. Especially, in the field of cardiology, these concepts can be used to explain complex clinical cardiac phenotypes like chronic heart failure and coronary artery disease. Cardiac diseases are biological complex entities which like other biological phenomena can be explained by a systems biology approach. The above powerful biological tools of systems biology can explain robustness growth and stability during disease process from modulation to phenotype. The purpose of the present review paper is to implement systems biology strategy and incorporate some conceptual issues raised by this approach into the clinical field of complex cardiac diseases. Cardiac disease process and progression can be addressed by the holistic realistic approach of systems biology in order to define in better terms earlier diagnosis and more effective therapy.

Novel Noninvasive Nuclear Medicine Imaging Techniques for Cardiac Inflammation

PURPOSE OF REVIEW

Inflammation is a key player in a wide range of cardiovascular and myocardial diseases. Given the numerous implications of inflammatory processes in disease initiation and progression, functional imaging modalities including positron emission tomography (PET) represent valuable diagnostic, prognostic, and monitoring tools in patient management. Since increased glucose metabolism is a hallmark of inflammation, PET using the radiolabeled glucose analog [18F]-2-deoxy-2-fluoro-d-glucose (FDG) is the mainstay diagnostic test for nuclear imaging of (cardiac) inflammation. Recently, new approaches using more specific tracers to overcome the limited specificity of FDG have emerged.

RECENT FINDINGS

PET imaging has proven its value in a number of inflammatory conditions of the heart including myocarditis, endocarditis, sarcoidosis, or reactive changes after myocardial infarction. In infection-related endocarditis, FDG-PET and white blood cell scintigraphy have been implemented in current guidelines. FDG-PET is considered as nuclear medical gold standard in myocarditis, pericarditis, or sarcoidosis. Novel strategies, including targeting of somatostatin receptors or C-X-C motif chemokine receptor CXCR4, have shown promising results in first studies.

SUMMARY

Nuclear medicine techniques offer valuable information in the assessment of myocardial inflammation. Given the possibility to directly visualize inflammatory activity, they represent useful tools for diagnosis, risk stratification, and therapy monitoring.

Mesenchymal Stem Cell Therapy for the Treatment of Heart Failure Caused by Ischemic or Non-ischemic Cardiomyopathy: Immunosuppression and Its Implications

HF patients with signs and symptoms of worsening heart failure (HF), despite optimal medical therapy, have a poor prognosis. The pathways contributing to HF are multiple, probably accounting, in part, for current treatment approaches not being more effective. Stem cells, particularly mesenchymal stem cells (MSCs), have a broad range of activities, making them particularly interesting candidates for a new HF therapeutic. This review presents an overview of the studies examining the efficacy of stem cell studies administered to HF patients, focusing mainly on MSCs. It examines the issues surrounding autologous vs. allogenic stem cells, the results of different routes of administration, and implications deriving from the belief that for stem cells to be effective, they must engraft in the myocardium and exert local effects. Since intravenous administration of stem cells leads to sparse cardiac engraftment, stem cell delivery strategies have uniformly involved catheter-based delivery systems. This becomes problematic in a disease that will almost certainly require delivery of the therapeutic throughout the course of the disease. Importantly, it appears that a critical contributing cause of the progressive cardiac dysfunction experienced by HF patients is the existence of a persistent inflammatory response. Since MSCs exert potent anti-inflammatory effects through paracrine mechanisms, it is possible that intravenous delivery of MSCs may be therapeutically effective. If this concept is valid, it could lead to a transformational change in stem cell delivery strategies.

Magnetic resonance imaging biomarkers of exercise-induced improvement of oxidative stress and inflammation in the brain of old high-fat-fed ApoE-/- mice

KEY POINTS

Vascular brain lesions and atherosclerosis are two similar conditions that are characterized by increased inflammation and oxidative stress. Non-invasive imaging in a murine model of atherosclerosis showed vascular brain damage and peripheral inflammation. In this study, exercise training reduced magnetic resonance imaging-detected abnormalities, insulin resistance and markers of oxidative stress and inflammation in old ApoE-/- mice. Our results demonstrate the protective effect of exercise on neurovascular damage in the ageing brain of ApoE-/- mice.

ABSTRACT

Vascular brain lesions, present in advanced atherosclerosis, share pathological hallmarks with peripheral vascular lesions, such as increased inflammation and oxidative stress. Physical activity reduces these peripheral risk factors, but its cerebrovascular effect is less documented, especially by non-invasive imaging. Through a combination of in vivo and post-mortem techniques, we aimed to characterize vascular brain damage in old ApoE-/- mice fed a high-cholesterol (HC) diet with dietary controlled intake. We then sought to determine the beneficial effects of exercise training on oxidative stress and inflammation in the brain as a treatment option in an ageing atherosclerosis mouse model. Using in vivo magnetic resonance imaging (MRI) and biological markers of oxidative stress and inflammation, we evaluated the occurrence of vascular abnormalities in the brain of HC-diet fed ApoE-/- mice >70 weeks old, its association with local and systemic oxidative stress and inflammation, and whether both can be modulated by exercise. Exercise training significantly reduced both MRI-detected abnormalities (present in 71% of untrained vs. 14% of trained mice) and oxidative stress (lipid peroxidation, 9.1 ± 1.4 vs. 5.2 ± 0.9 μmol mg-1 ; P < 0.01) and inflammation (interleukin-1β, 226.8 ± 27.1 vs. 182.5 ± 21.5 pg mg-1 ; P < 0.05) in the brain, and the mortality rate. Exercise also decreased peripheral insulin resistance, oxidative stress and inflammation, but significant associations were seen only within brain markers. Highly localized vascular brain damage is a frequent finding in this ageing atherosclerosis model, and exercise is able to reduce this outcome and improve lifespan. In vivo MRI evaluated both the neurovascular damage and the protective effect of exercise.

Imaging High-Risk Atherosclerotic Plaques with PET

OPINION STATEMENT

Atherosclerotic disease, a primary cause of stroke and myocardial infarction, is the most common underlying cause of death worldwide. While atherosclerosis was formerly considered to be a relatively inert structural abnormality, decades of research have since shown that it is a biologically active process, driven by active inflammation. In concert with this conceptual shift, newer strategies to image vascular lesions have evolved. ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography (PET) imaging has been validated as a non-invasive tool to characterize atherosclerotic inflammation. It is hypothesized that a combination of structural and biological (e.g., inflammatory) imaging may provide better means to assess clinical risk, to assess efficacy of therapy, and to identify new, effective treatments. Limitations remain, however, and further advances in technology and tracer development are required before FDG PET imaging will contribute a significant clinical impact at the level of the individual patient.

Targeting Amino Acid Metabolism for Molecular Imaging of Inflammation Early After Myocardial Infarction

Acute tissue inflammation after myocardial infarction influences healing and remodeling and has been identified as a target for novel therapies. Molecular imaging holds promise for guidance of such therapies. The amino acid (11)C-methionine is a clinically approved agent which is thought to accumulate in macrophages, but not in healthy myocytes. We assessed the suitability of positron emission tomography (PET) with (11)C-methionine for imaging post-MI inflammation, from cell to mouse to man. Uptake assays demonstrated 7-fold higher (11)C-methionine uptake by polarized pro-inflammatory M1 macrophages over anti-inflammatory M2 subtypes (p<0.001). C57Bl/6 mice (n=27) underwent coronary artery ligation or no surgery. Serial (11)C-methionine PET was performed 3, 5 and 7d later. MI mice exhibited a perfusion defect in 32-50% of the left ventricle (LV). PET detected increased (11)C-methionine accumulation in the infarct territory at 3d (5.9±0.9%ID/g vs 4.7±0.9 in remote myocardium, and 2.6±0.5 in healthy mice; p<0.05 and <0.01 respectively), which declined by d7 post-MI (4.3±0.6 in infarct, 3.4±0.8 in remote; p=0.03 vs 3d, p=0.08 vs healthy). Increased (11)C-methionine uptake was associated with macrophage infiltration of damaged myocardium. Treatment with anti-integrin antibodies (anti-CD11a, -CD11b, -CD49d; 100µg) lowered macrophage content by 56% and (11)C-methionine uptake by 46% at 3d post-MI. A patient study at 3d after ST-elevation MI and early reperfusion confirmed elevated (11)C-methionine uptake in the hypoperfused myocardial region. Targeting of elevated amino acid metabolism in pro-inflammatory M1 macrophages enables PET imaging-derived demarcation of tissue inflammation after MI. (11)C-methionine-based molecular imaging may assist in the translation of novel image-guided, inflammation-targeted regenerative therapies.

Unexpected arterial wall and cellular inflammation in patients with rheumatoid arthritis in remission using biological therapy: a cross-sectional study

Background

Increasing numbers of patients (up to 40 %) with rheumatoid arthritis (RA) achieve remission, yet it remains to be elucidated whether this also normalizes their cardiovascular risk. Short-term treatment with TNF inhibitors lowers arterial wall inflammation, but not to levels of healthy controls. We investigated whether RA patients in long-term remission are characterized by normalized inflammatory activity of the arterial wall and if this is dependent on type of medication used (TNF-inhibitor versus nonbiological disease-modifying antirheumatic drugs (DMARDs)).

Methods

Arterial wall inflammation, bone marrow and splenic activity (index of progenitor cell activity) was assessed with ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) in RA patients in remission (disease activity score (DAS28) <2.6 for >6 months) and healthy controls. We performed ex vivo characterization of monocytes using flow cytometry and a transendothelial migration assay.

Results

Overall, arterial wall inflammation was comparable in RA patients (n = 23) in long-term remission and controls (n = 17). However, RA subjects using current anti-TNF therapy (n = 13, disease activity score 1.98[1.8–2.2]) have an almost 1.2-fold higher ¹⁸F-FDG uptake in the arterial wall compared to those using DMARDs (but with previous anti-TNF therapy) (n = 10, disease activity score 2.24[1.3–2.5]), which seemed to be predominantly explained by longer duration of their rheumatic disease in a multivariate linear regression analysis. This coincided with increased expression of pro-adhesive (CCR2) and migratory (CD11c, CD18) surface markers on monocytes and a concomitant increased migratory capacity. Finally, we found increased activity in bone marrow and spleen in RA patients using anti-TNF therapy compared to those with DMARDs and controls.

Conclusions

A subset of patients with RA in clinical remission have activated monocytes and increased inflammation in the arterial wall, despite the use of potent TNF blocking therapies. In these subjects, RA disease duration was the most important contributor to the level of arterial wall inflammation. This increased inflammatory state implies higher cardiovascular risk in these patients, who thus may require more stringent CV risk management.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-1008-z) contains supplementary material, which is available to authorized users.

Coronary Atherosclerosis: Pathophysiologic Basis for Diagnosis and Management

Coronary atherosclerosis is a long lasting and continuously evolving disease with multiple clinical manifestations ranging from asymptomatic to stable angina, acute coronary syndrome (ACS), heart failure (HF) and sudden cardiac death (SCD). Genetic and environmental factors contribute to the development and progression of coronary atherosclerosis. In this review, current knowledge related to the diagnosis and management of coronary atherosclerosis based on pathophysiologic mechanisms will be discussed. In addition to providing state-of-the-art concepts related to coronary atherosclerosis, special consideration will be given on how to apply data from epidemiologic studies and randomized clinical trials to the individual patient. The greatest challenge for the clinician in the twenty-first century is not in absorbing the fast accumulating new knowledge, but rather in applying this knowledge to the individual patient.

Mechanisms Contributing to the Progression of Ischemic and Nonischemic Dilated Cardiomyopathy: Possible Modulating Effects of Paracrine Activities of Stem Cells

Over the past 1.5 decades, numerous stem cell trials have been performed in patients with cardiovascular disease. Although encouraging outcome signals have been reported, these have been small, leading to uncertainty as to whether they will translate into significantly improved outcomes. A reassessment of the rationale for the use of stem cells in cardiovascular disease is therefore timely. Such a rationale should include analyses of why previous trials have not produced significant benefit and address whether mechanisms contributing to disease progression might benefit from known activities of stem cells. The present paper provides such a reassessment, focusing on patients with left ventricular systolic dysfunction, either nonischemic or ischemic. We conclude that many mechanisms contributing to progressive left ventricular dysfunction are matched by stem cell activities that could attenuate the myocardial effect of such mechanisms. This suggests that stem cell strategies may improve patient outcomes and justifies further testing.

Improving Cell Engraftment in Cardiac Stem Cell Therapy

Myocardial infarction (MI) affects millions of people worldwide. MI causes massive cardiac cell death and heart function decrease. However, heart tissue cannot effectively regenerate by itself. While stem cell therapy has been considered an effective approach for regeneration, the efficacy of cardiac stem cell therapy remains low due to inferior cell engraftment in the infarcted region. This is mainly a result of low cell retention in the tissue and poor cell survival under ischemic, immune rejection and inflammatory conditions. Various approaches have been explored to improve cell engraftment: increase of cell retention using biomaterials as cell carriers; augmentation of cell survival under ischemic conditions by preconditioning cells, genetic modification of cells, and controlled release of growth factors and oxygen; and enhancement of cell survival by protecting cells from excessive inflammation and immune surveillance. In this paper, we review current progress, advantages, disadvantages, and potential solutions of these approaches.