Epicardial Adipose Tissue in Myocardial Disease: From Physiology to Heart Failure Phenotypes

Epicardial adipose tissue (EAT) is increasingly being recognized as a determinant of myocardial biology. The EAT-heart crosstalk suggests causal links between dysfunctional EAT and cardiomyocyte impairment. Obesity promotes EAT dysfunction and shifts in secreted adipokines which adversely affect cardiac metabolism, induce cardiomyocyte inflammation, redox imbalance and myocardial fibrosis. Thus, EAT determines cardiac phenotype via effects on cardiac energetics, contractility, diastolic function, and atrial conduction. Vice-versa the EAT is altered in heart failure (HF), and such phenotypic changes can be detected by noninvasive imaging or incorporated in Artificial Intelligence-enhanced tools to aid the diagnosis, subtyping or risk prognostication of HF. In the present article, we summarize the links between EAT and the heart, explaining how the study of epicardial adiposity can improve the understanding of cardiac disease, serve as a source of diagnostic and prognostic biomarkers, and as a potential therapeutic target in HF to improve clinical outcomes.

Oxidative Stress Biomarkers in Coronary Artery Disease

Oxidative stress plays a central role in atherogenesis, implicated in endothelial dysfunction, coronary plaque formation, and destabilization. Therefore, identifying oxidative stress in the vascular wall by reliable biomarkers could aid in early diagnosis and better coronary artery disease (CAD) prognostication. Because of the short half-life of reactive oxygen species, the current approach is to measure stable products generated by the oxidation of macromolecules in plasma or urine. Most popular oxidative stress biomarkers are oxidized low-density lipoprotein, myeloperoxidase and lipid peroxidation biomarkers, such as malondialdehyde and F2-isoprostanes. Oxidative protein modification biomarkers and oxidized phospholipids have also been studied and discussed in the present review. Most of these biomarkers are associated with the presence and extent of CAD, are elevated in patients with acute coronary syndromes, and may predict outcomes independent of traditional CAD risk factors. However, further standardization of measurement methods and assessment in large randomized clinical trials are required to integrate these biomarkers into clinical practice. In addition, evidence that these biomarkers detect oxidative stress in the vascular wall lacks and more specific biomarkers should be developed to identify vascular oxidative stress. Consequently, several oxidative stress biomarkers have been developed, most of which can be associated with the presence and extent of CAD and event prognosis. However, they still have significant limitations that hinder their integration into clinical practice.

Interleukin-6 Signaling in Atherosclerosis: From Molecular Mechanisms To Clinical Outcomes

Interleukin-6 (IL-6) is a cytokine centrally involved in several immune responses and it has been recognized as a driver of enhanced atherothrombotic risk. Immunity and inflammation are intrinsically involved in atherosclerosis progression. This generated 'inflammation hypothesis', which is now validated in large-scale clinical trials. Abundant evidence supports the distinctive role of IL-6 in coronary artery disease. The focus on this cytokine stems from epidemiological studies linking high plasma concentrations of IL-6 with greater risk for adverse cardiovascular events, genetic studies which implicate a causative role of IL-6 in atherosclerosis and murine data which support the involvement of IL-6 in various pathophysiological cascades of atherothrombosis. The fact that high IL-6 levels are equivalent to increased cardiovascular risk created an unmet need to address those who are at 'residual inflammatory risk'. Moreover, the opposing effects of IL-6 underlined the importance of deciphering specific signaling cascades, which may be responsible for different effects. Finally, murine data and some small clinical trials highlighted the possibility of reversing the pro-atherogenic effects of IL-6 by directly targeting it. While IL-1 blockage was proved effective, it is reasonable to examine if moving more downstream in the inflammation cascade could be more selective and effective than other anti-inflammatory therapies. In the present review, we examine the role of IL-6 as a biomarker of 'residual inflammatory risk', its vital role in the pathophysiology of atherosclerosis progression and the possibility of targeting it to stall coronary artery disease progression.

Lipoprotein(a) and inflammation- pathophysiological links and clinical implications for cardiovascular disease

The role of lipoprotein(a) (Lp[a]) as a significant and possibly causal cardiovascular disease (CVD) risk factor has been well established. Many studies, mostly experimental, have supported inflammation as a mediator of Lp(a)-induced increase in CVD risk. Lp(a), mainly through oxidized phospholipids bound to its apolipoprotein(a) part, leads to monocyte activation and endothelial dysfunction. The relationship between Lp(a) and inflammation is bidirectional as Lp(a) levels, besides being associated with inflammatory properties, are regulated by inflammatory stimuli or anti-inflammatory treatment. Reduction of Lp(a) concentration, especially by potent siRNA agents, contributes to partial reversion of the Lp(a) related inflammatory profile. This review aims to present the current pathophysiological and clinical evidence of the relationship between Lp(a) and inflammation.

Stem Cell-based Therapies in Cardiovascular Diseases: From Pathophysiology to Clinical Outcomes

Over 20 years of intensified research in the field of stem cells brought about unprecedented possibilities in treating heart diseases. The investigators were initially fascinated by the idea of regenerating the lost myocardium and replacing it with new functional cardiomyocytes, but this was extremely challenging. However, the multifactorial effects of stem cell-based therapies beyond mere cardiomyocyte generation, caused by paracrine signaling, would open up new possibilities in treating cardiovascular diseases. To date, there is a strong body of evidence that the anti-inflammatory, anti-apoptotic, and immunomodulatory effects of stem cell therapy may alleviate atherosclerosis progression. In the present review, our objective is to provide a brief overview of the stem cell-based therapeutic options. We aim to delineate the pathophysiological mechanisms of their beneficial effects in cardiovascular diseases especially in coronary artery disease and to highlight some conclusions from important clinical studies in the field of regenerative medicine in cardiovascular diseases and how we could further move onwards.