Adipokines in atherosclerosis: unraveling complex roles

Adiponectin: its role in diabetic and pancreatic cancer

Adiponectin (ApN) is an antidiabetic and anti-inflammatory protein synthesized by adipose tissue. It is essential in regulating insulin sensitivity, glucose, and lipid metabolism by controlling AMPK, PPARα, and MAPK signals. It is an anti-inflammatory property that protects pancreatic β-cells. Often, low levels of ApN are linked to obesity, type II diabetes and the development of PDAC. However, changes in lifestyle and the use of certain drugs can improve ApN function and insulin sensitivity. PDAC is a highly aggressive cancer linked to obesity, type II diabetes, and insulin resistance. ApN plays a complex role in PDAC progression and can suppress PDAC development by weakening β-catenin signaling. Decreases in ApN levels are associated with increased PDAC risk in diabetic patients. PDAC and diabetes are interconnected through the development of insulin resistance, islet dysfunction, change in immunological response, inflammation, oxidative stress, and altered hormone secretion. Genetic studies highlight specific genes like HNF4G and PDX1 that influence both conditions and miRNAs such as miR-19a promote tumor progression through the PI3K/AKT pathway. This review discusses the role of ApN in diabetes and PDAC and the interrelation between diabetes and PDAC.

NOTCH Signaling Networks in Perivascular Adipose Tissue

Over a hundred years ago, mutants were detected in Drosophila melanogaster that led to a NOTCH in the wing tip. This original phenotype was reflected in the nomenclature of the gene family that was later cloned and characterized in the 1980s and found to be conserved across metazoans. NOTCH signaling relies on transmembrane ligands and receptors that require cellular contact for receptor activation, reflecting its role in multicellular organisms as an intercellular signaling strategy. In humans, mutations in genes encoding NOTCH and their ligands have been shown to promote human disease; these aspects have been extensively reviewed. Notch signaling plays important roles in vascular development (vasculogenesis and angiogenesis) and homeostasis. NOTCH signaling is also active in adipose tissue and contributes to adipocyte differentiation. In addition, NOTCH activity regulates functions of other metabolic organs. This review focuses on NOTCH activity in perivascular adipose tissue within the vascular microenvironment as defined by mouse studies and summarizes expression and potential signaling of the NOTCH signaling network in human perivascular adipose tissue. Due to the strong activity of NOTCH in regulation of metabolic function, activation of the NOTCH network in specific cell types in perivascular adipose tissue has implications for signaling to the underlying blood vessel and control of vascular health and disease.

Obesity, White Adipose Tissue, and Adipokines Signaling in Male Reproduction

Currently, obesity is a global pandemic characterized by systemic metabolic complications that negatively impact several organs, including white adipose tissue (WAT) and the tissues of the male reproductive system. Since the discovery of leptin in 1994, WAT has been recognized as a dynamic endocrine organ for secreting a series of molecules with hormonal functions, collectively called adipokines. The link between obesity, WAT, adipokines, and the male reproductive system is direct and little explored. With changes in nutritional status, WAT undergoes morphofunctional changes, and the secretion of adipokines is altered, negatively impacting reproductive mechanisms, including steroidogenesis and spermatogenesis. In this review, we address in an updated way the structural and functional characteristics of WAT as well as the link between obesity and changes in the signaling pathways of the adipokines leptin, adiponectin, resistin, visfatin, apelin, chemerin, omentin-1, vaspin, and asprosin in male reproduction. Understanding the relationship between obesity, these adipokines, and reproductive dysfunction can contribute to new strategies for the treatment of subfertility and male infertility.

Mitochondrial dysfunction and calcium homeostasis in heart failure: Exploring the interplay between oxidative stress and cardiac remodeling for future therapeutic innovations

Heart failure (HF) is a multifaceted clinical syndrome characterized by the heart's inability to pump sufficient blood to meet the body's metabolic demands. It arises from various etiologies, including myocardial injury, hypertension, and valvular heart disease. A critical aspect of HF pathophysiology involves mitochondrial dysfunction, particularly concerning calcium (Ca2+) homeostasis and oxidative stress. This review highlights the pivotal role of excess mitochondrial Ca2+ in exacerbating oxidative stress, contributing significantly to HF progression. Novel insights are provided regarding the mechanisms by which mitochondrial Ca2+ overload leads to increased production of reactive oxygen species (ROS) and impaired cellular function. Despite this understanding, key gaps in research remain, particularly in elucidating the complex interplay between mitochondrial dynamics and oxidative stress across different HF phenotypes. Furthermore, therapeutic strategies targeting mitochondrial dysfunction are still in their infancy, with limited applications in clinical practice. By summarizing recent findings and identifying these critical research gaps, this review aims to pave the way for innovative therapeutic approaches that improve the management of heart failure, ultimately enhancing patient outcomes through targeted interventions.

Plasma Atrial Natriuretic Peptide Predicts Oxidized Low-Density Lipoprotein Levels in Type 2 Diabetes Mellitus Patients Independent of Circulating Adipokine and Cytokine

Atrial natriuretic peptide (ANP) and oxidized low-density lipoprotein (ox-LDL) play essential roles in the development and progression of vascular complications associated with type 2 diabetes mellitus (T2DM), and both are independently linked to cardiovascular diseases (CVD). However, the relationship between ANP and ox-LDL in patients with T2DM remains unclear as previous studies have primarily focused on circulating levels in various diseases. This study investigated the relationship between ANP and ox-LDL levels in obese individuals with T2DM. The cohort included 57 patients with T2DM (mean age 61.14 ± 9.99 years; HbA1c 8.66 ± 1.60%; BMI 35.15 ± 6.65 kg/m2). Notably, 95% of the patients had hypertension, 82% had dyslipidemia, 59% had an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2, 14% had coronary artery disease (CAD), and 5% had a history of stroke. Plasma concentrations of ANP and ox-LDL were measured using ELISA. Adipokines and cytokines levels were measured using the multiplex® MAP Human Adipokine Magnetic Beads Spearman's correlation analysis which revealed a negative correlation between ANP and ox-LDL (r = -0.446, p = 0.001) as well as with the ox-LDL/apoB ratio (r = -0.423, p = 0.001) and ox-LDL/LDLc ratio (r = -0.307, p = 0.038). Multivariable regression analysis indicated that ANP was independently associated with ox-LDL (β = -115.736, p = 0.005). Stepwise linear regression further identified TNFα, leptin, and adiponectin as the strongest predictors influencing the relationship between ANP and ox-LDL levels (β = -64.664, p = 0.0311, and r2 = 0.546 for the model). However, these factors did not significantly mediate this association. This study emphasizes the need for further exploration of the complex interaction between ANP and ox-LDL in larger patient populations. This could provide valuable insights into potential therapeutic approaches for managing vascular complications in obese individuals with T2DM.

Adiponectin and Adiponectin Receptors in Atherosclerosis

Adiponectin is an abundantly secreted hormone that communicates information between the adipose tissue, and the immune and cardiovascular systems. In metabolically healthy individuals, adiponectin is usually found at high levels and helps improve insulin responsiveness of peripheral tissues, glucose tolerance, and fatty acid oxidation. Beyond its metabolic functions in insulin-sensitive tissues, adiponectin plays a prominent role in attenuating the development of atherosclerotic plaques, partially through regulating macrophage-mediated responses. In this context, adiponectin binds to its receptors, adiponectin receptor 1 (AdipoR1) and AdipoR2 on the cell surface of macrophages to activate a downstream signaling cascade and induce specific atheroprotective functions. Notably, macrophages modulate the stability of the plaque through their ability to switch between proinflammatory responders, and anti-inflammatory proresolving mediators. Traditionally, the extremes of the macrophage polarization spectrum span from M1 proinflammatory and M2 anti-inflammatory phenotypes. Previous evidence has demonstrated that the adiponectin-AdipoR pathway influences M1-M2 macrophage polarization; adiponectin promotes a shift toward an M2-like state, whereas AdipoR1- and AdipoR2-specific contributions are more nuanced. To explore these concepts in depth, we discuss in this review the effect of adiponectin and AdipoR1/R2 on 1) metabolic and immune responses, and 2) M1-M2 macrophage polarization, including their ability to attenuate atherosclerotic plaque inflammation, and their potential as therapeutic targets for clinical applications.

Systematic review and meta-analyses of adipokine levels in hypothyroidism: a role for retinol-binding protein 4

BACKGROUND

Hypothyroidism (HT) is associated with numerous well-characterized comorbidities and established biomarkers for subclinical atherosclerosis which may lead to an elevated risk of cardiovascular disease; however, the precise molecular mechanism underlying these pathological features remains elusive. Increased levels of adipokines may have adverse effects on multiple atherosclerotic risk factors in HT. Different studies have evaluated the association between HT and adipokines with conflicting results.

METHODS

A systematic review and meta-analyses were conducted to provide an overview of adipokine levels in HT. The last literature search was done in February 2024 for studies analyzing traditional and novel circulating adipokines levels (excluding resistin and irisin) in patients with HT. The standard mean differences and 95% confidence intervals (CI) were calculated using random-effect models except if no heterogeneity was found.

RESULTS

HT was not associated with leptin, adiponectin, omentin-1, visfatin, or apelin levels; however, increased retinol-binding protein 4 (RPB4) levels were found in both overall and subclinical HT (p-values = 0.0002 and 0.004 respectively).

CONCLUSION

While pooled analysis suggested a role for RBP4 in hypothyroid patients, associations do not imply cause-effect relationships, and therefore the potential clinical implications of these findings should await further mechanistic studies.

REGISTRATION

The protocol has been registered in the Prospective Register of Systematic Reviews (PROSPERO) under the identification number CRD42024537717.

Effect of Low- and Moderate-Intensity Aerobic Training on Body Composition Cardiorespiratory Functions, Biochemical Risk Factors and Adipokines in Morbid Obesity

BACKGROUND

Obesity poses an enormous public health and economic burden worldwide. Visceral fat accumulation is associated with various metabolic and cardiovascular consequences, resulting in an increased prevalence of atherosclerotic conditions. We aimed to examine the impact of low-and moderate-intensity aerobic training on several anthropometric and cardiorespiratory parameters and markers of atherosclerosis, including inflammation, serum levels of lipoproteins and adipokines of extremely obese patients in poor condition.

METHODS

Forty severely obese patients were recruited and randomized into two groups, Group 1 and Group 2, for a six-week inpatient study. Group 1 received moderate-intensity (40-60% heart rate reserve) and Group 2 received low-intensity (30-39% of heart rate reserve) aerobic training combined with resistance training. The patients' cardiorespiratory functions were assessed by ergospirometry. Anthropometric data were recorded, body composition was analyzed and functional tests were performed. We also investigated serum lipids and high-sensitive C-reactive protein levels and calculated the homeostatic model assessment-insulin resistance indices and adipokine levels as predictive biomarkers.

RESULTS

Functional abilities and some biochemical parameters, such as homeostatic model assessment-insulin resistance, serum lipids, apolipoprotein A and apolipoprotein-B improved in both groups in a positive direction. However, cardiorespiratory capacity and the serum levels of high-sensitive C-reactive protein and Lipocalin-2 decreased, while irisin and paraoxonase 1 increased significantly, but only in Group 1.

CONCLUSIONS

Six weeks of aerobic training, regardless of its intensity, could induce favorable changes in functional tests, body composition and serum lipids, even in severely obese, extremely unconditioned patients in both groups. However, moderate-intensity aerobic training should at least increase cardiorespiratory capacity and yield a better lipid profile oxidative status and inflammation profile.

Common Genetic Factors May Play a Role in the Relationships Between Body Composition, Adipokines, and Low-Back-Pain-Related Disability

In this study, we evaluated the contribution of the putative genetic factors into the established associations between selected circulating adipokine levels, body composition measurements, and low-back-pain-related disability scores (LBP_DS). A total of 1078 individuals from 98 nuclear families (with 1 to 11 siblings per family) were examined. A detailed self-report questionnaire was used to collect LBP disability data; body composition (fat, skeletal muscle mass, and extracellular water (ECW)) was assessed using the bioimpedance method; plasma levels of adipokines were measured by ELISA. Pedigree-based statistical analysis methods were used, including family-based variance component analysis (VCA) and principal phenotype analysis (PPA), to estimate the contribution of potential genetic and environmental factors. The VCA revealed a significant additive genetic component in LBP_DS and for the selected body composition phenotypes and adipokines. The study also revealed that both adipokines (GDF-15, chemerin, and follistatin) and body composition variables (BMI, fat mass/weight, waist circumference, and ECW) were genetically correlated with LBP_DS. Next, PPA generated two synthetic phenotypes: PPCT (combining cytokines) and PPBC (combining body composition variables). There was no significant correlation between the putative genetic factors underlying the created PPs. However, each of them displayed a significant genetic correlation with LBP_DS. These findings indicate that genetic factors that are assumingly common for several adipokine variations and several body composition measurements, respectively, presumably have a pleotropic genetic influence on the LBP_DS variation, independently from one another. This, in turn, suggests that the alleged genetic factors employing pleiotropic effects on LBP_DS have a complex and probably non-overlapping composition.

From Atherosclerotic Plaque to Myocardial Infarction-The Leading Cause of Coronary Artery Occlusion

Cardiovascular disease (CVD) constitutes the most common cause of death worldwide. In Europe alone, approximately 4 million people die annually due to CVD. The leading component of CVD leading to mortality is myocardial infarction (MI). MI is classified into several types. Type 1 is associated with atherosclerosis, type 2 results from inadequate oxygen supply to cardiomyocytes, type 3 is defined as sudden cardiac death, while types 4 and 5 are associated with procedures such as percutaneous coronary intervention and coronary artery bypass grafting, respectively. Of particular note is type 1, which is also the most frequently occurring form of MI. Factors predisposing to its occurrence include, among others, high levels of low-density lipoprotein cholesterol (LDL-C) in the blood, cigarette smoking, chronic kidney disease (CKD), diabetes mellitus (DM), hypertension, and familial hypercholesterolaemia (FH). The primary objective of this review is to elucidate the issues with regard to type 1 MI. Our paper delves into, amidst other aspects, its pathogenesis, risk assessment, diagnosis, pharmacotherapy, and interventional treatment options in both acute and long-term conditions.

The Role of FNDC5/Irisin in Cardiovascular Disease

Disorders of cardiomyocyte metabolism play a crucial role in many cardiovascular diseases, such as myocardial infarction, heart failure and ischemia-reperfusion injury. In myocardial infarction, cardiomyocyte metabolism is regulated by mitochondrial changes and biogenesis, which allows energy homeostasis. There are many proteins in cells that regulate and control metabolic processes. One of them is irisin (Ir), which is released from the transmembrane protein FNDC5. Initial studies indicated that Ir is a myokine secreted mainly by skeletal muscles. Further studies showed that Ir was also present in various tissues. However, its highest levels were observed in cardiomyocytes. Ir is responsible for many processes, including the conversion of white adipose tissue (WAT) to brown adipose tissue (BAT) by increasing the expression of thermogenin (UCP1). In addition, Ir affects mitochondrial biogenesis. Therefore, the levels of FNDC5/Ir in the blood and myocardium may be important in cardiovascular disease. This review discusses the current knowledge about the role of FNDC5/Ir in cardiovascular disease.

Mitochondrial Melatonin: Beneficial Effects in Protecting against Heart Failure

Cardiovascular disease is the cause of physical infirmity and thousands of deaths annually. Typically, during heart failure, cardiomyocyte mitochondria falter in terms of energy production and metabolic processing. Additionally, inflammation and the accumulation of non-contractile fibrous tissue contribute to cardiac malfunction. Melatonin, an endogenously produced molecule, experimentally reduces the initiation and progression of atherosclerotic lesions, which are often the basis of coronary artery disease. The current review critically analyzes published data related to the experimental use of melatonin to forestall coronary artery pathologies. Collectively, these studies document melatonin's anti-atherosclerotic actions in reducing LDL oxidation and triglyceride levels, lowering endothelial malfunction, limiting adhesion molecule formation, preventing macrophage polarization to the M1 pro-inflammatory phenotype, changing cellular metabolism, scavenging destructive reactive oxygen species, preventing the proliferation and invasion of arterial smooth muscle cells into the lesioned area, restricting the ingrowth of blood vessels from the vasa vasorum, and solidifying the plaque cap to reduce the chance of its rupture. Diabetic hyperglycemia, which aggravates atherosclerotic plaque formation, is also inhibited by melatonin supplementation in experimental animals. The potential value of non-toxic melatonin as a possible inhibitor of cardiac pathology in humans should be seriously considered by performing clinical trials using this multifunctional molecule.