S100B: role in cardiac remodeling and function following myocardial infarction in diabetes

Role of S100β in Patients with Unstable Angina Pectoris: Insights from Quantitative Flow Ratio

BACKGROUND AND OBJECTIVE

Disturbed autonomic nervous system (ANS) may promote inflammatory, immune, and oxidative stress responses, which may increase the risk of acute coronary events. S100β has been proposed as a biomarker of neuronal injury that would provide an insightful understanding of the crosstalk between the ANS, immune-inflammatory cells, and plaques that drive atherosclerosis. This study investigates the correlation between S100β, and functional coronary stenosis as determined by quantitative flow ratio (QFR).

METHODS

Patients with unstable angina pectoris (UAP) scheduled for coronary angiography and QFR were retrospectively enrolled. Serum S100β levels were determined by enzyme-linked immunosorbent assay. The Gensini score was used to estimate the extent of atherosclerotic lesions and the cumulative sum of three-vessel QFR (3V-QFR) was calculated to estimate the total atherosclerotic burden.

RESULTS

Two hundred thirty-three patients were included in this study. Receiver operator characteristic (ROC) curve indicated that S100β>33.28 pg/mL predicted functional ischemia in patients with UAP. Multivariate logistic analyses showed that a higher level of S100β was independently correlated with a functional ischemia-driven target vessel (QFR ≤0.8). This was also closely correlated with the severity of coronary lesions, as measured by the Gensini score (OR = 5.058, 95% CI: 2.912-8.793, p <0.001). According to 3V-QFR, S100β is inversely associated with total atherosclerosis burden (B = -0.002, p <0.001).

CONCLUSIONS

S100β was elevated in the functional ischemia stages of UAP. It was independently associated with coronary lesion severity as assessed by Gensini score and total atherosclerosis burden as estimated by 3V-QFR in patients with UAP.

Immune-related biomarkers in myocardial infarction; diagnostic/prognostic value and therapeutic potential

The incidence of myocardial infarction (MI) is increasing worldwide on an annual basis. The incorporation of circulating biomarkers, along with electrocardiography, echocardiography, coronary angiograms, and other diagnostic techniques, is essential in the evaluation, prediction, and therapeutic efficacy assessment of patients afflicted with MI. Biomarker evaluation has been employed in the diagnosis of MI for over five decades. Further biomarker research can be carried out as newer biomarkers have been discovered in pathways such as inflammatory response, neurohormonal stimulation, or myocardial stress that initiate significantly earlier than myocyte necrosis and the diagnostic establishment of cardiac troponins. The assessment of biomarkers for MI is on the brink of a significant transformation due to advancements in comprehending the intricate pathophysiology of the condition. This has led to a pursuit of innovative biomarkers that could potentially overcome the limitations of current biomarkers. For individuals with a high-risk profile, this may facilitate tailoring of appropriate treatment. This review places emphasis on a diverse array of biomarkers that have the potential to offer diagnostic and prognostic information, as well as the latest clinical and preclinical evidence that is driving theoretical advancements in cardiovascular immunotherapy.

S100 proteins in cardiovascular diseases

Cardiovascular diseases have become a serious threat to human health and life worldwide and have the highest fatality rate. Therefore, the prevention and treatment of cardiovascular diseases have become a focus for public health experts. The expression of S100 proteins is cell- and tissue-specific; they are implicated in cardiovascular, neurodegenerative, and inflammatory diseases and cancer. This review article discusses the progress in the research on the role of S100 protein family members in cardiovascular diseases. Understanding the mechanisms by which these proteins exert their biological function may provide novel concepts for preventing, treating, and predicting cardiovascular diseases.

Galectin-3 and soluble RAGE as new biomarkers of post-infarction cardiac remodeling

Post-infarction remodeling is a clinical problem with no curative treatment. Our objective was to search for new biomarkers of cardiac remodeling that have clinical value after ST-segment elevation myocardial infarction (STEMI). This pilot study enrolled 67 consecutive patients with de novo STEMI who underwent revascularization by primary angioplasty. Echocardiography studies of cardiac function were completed during the first 48 h post-STEMI and after 6 months of follow-up. Galectin-3 and soluble receptor for advanced glycation end products (sRAGE) were tested in the peripheral venous blood during the 24 h post-infarction. Cardiac remodeling was defined as changes ≥ 15% in the left ventricular end-systolic volume (LVESV) or > 10% in the left atrial area (LAA). An inverse association was found between galectin-3 (r_s = - 0.296; p < 0.001) and sRAGE (r_s = - 0.327; p < 0.001) levels and the basal left ventricle ejection fraction (LVEF). However, only galectin-3 was directly associated with the increase in LVESV (r_s = 0.389; p = 0.007) and LVEDV (r_s = 0.314; p = 0.031) during the follow-up. sRAGE was inversely related to the change in LAA (r_s = - 0.320; p = 0.032). These data are consistent with galectin-3, but not sRAGE levels, as a predictor of left ventricle remodeling (OR 1.036, 95% CI 1.002-1.071; p = 0.039). Galectin-3 and sRAGE levels that were measured during hospitalization are inversely related to basal LVEF after a STEMI. Galectin-3 levels are a predictor of adverse post-STEMI LV remodeling, whereas sRAGE levels exhibited an inverse relationship with left atrial remodeling. KEY MESSAGES: Post-infarction remodeling is a clinical problem with no curative treatment. New biomarkers for remodeling after acute myocardial infarction were explored. Early post-STEMI galectin-3 and soluble RAGE are inversely related with left ventricle function. Galectin-3 levels were predictors of adverse post-STEMI left ventricle remodeling. Soluble RAGE levels were associated with left atrial remodeling.

Diagnostic and Prognostic Biomarkers for Myocardial Infarction

The incidence of myocardial infarction (MI) increases every year worldwide. Better diagnostic and prognostic biomarkers for clinical applications are the consistent pursuit of MI research. In addition to electrocardiogram, echocardiography, coronary angiography, etc., circulating biomarkers are essential for the diagnosis, prognosis, and treatment effect monitoring of MI patients. In this review, we assessed both strength and weakness of MI circulating biomarkers including: (1) originated from damaged myocardial tissues including current golden standard cardiac troponin, (2) released from non-myocardial tissues due to MI-induced systems reactions, and (3) preexisted in blood circulation before the occurrence of MI event. We also summarized newly reported MI biomarkers. We proposed that the biomarkers preexisting in blood circulation before MI incidents should be emphasized in research and development for MI prevention in near future.

Circulating Ligands of the Receptor for Advanced Glycation End Products and the Soluble Form of the Receptor Modulate Cardiovascular Cell Apoptosis in Diabetes

We determined whether plasma concentrations of the receptor for advanced glycation end products (RAGE) and the soluble (s) form of RAGE (sRAGE) in healthy individuals and patients with type 2 diabetes (T2D) modulate vascular remodeling. Healthy individuals and patients with T2D were divided into two age groups: young = <35 years old or middle-aged (36-64 years old) and stratified based on normal glucose tolerance (NGT), impaired (IGT), and T2D. Plasma titers of sRAGE, the RAGE ligands, AGEs, S100B, S100A1, S100A6, and the apoptotic marker Fas ligand Fas(L) were measured by enzyme-linked immunosorbent assay (ELISA). The apoptotic potential of the above RAGE ligands and sRAGE were assessed in cultured adult rat aortic smooth muscle cells (ASMC). In NGT individuals, aging increased the circulating levels of AGEs and S100B and decreased sRAGE, S100A1 and S100A6. Middle-aged patients with T2D presented higher levels of circulating S100B, AGEs and FasL, but lower levels of sRAGE, S100A1 and S100A6 than individuals with NGT or IGT. Treatment of ASMC with either AGEs or S100B at concentrations detected in T2D patients increased markers of inflammation and apoptosis. Responses attenuated by concomitant administration of sRAGE. In middle-aged patients with T2D, lower circulating plasma levels of sRAGE may limit decoy and exogenous trapping of deleterious pro-apoptotic/pro-inflammatory RAGE ligands AGEs and S100B, increasing the risk for diabetic complications.

Receptor for Advanced Glycation End Products (RAGE) and Mechanisms and Therapeutic Opportunities in Diabetes and Cardiovascular Disease: Insights From Human Subjects and Animal Models

Obesity and diabetes are leading causes of cardiovascular morbidity and mortality. Although extensive strides have been made in the treatments for non-diabetic atherosclerosis and its complications, for patients with diabetes, these therapies provide less benefit for protection from cardiovascular disease (CVD). These considerations spur the concept that diabetes-specific, disease-modifying therapies are essential to identify, especially as the epidemics of obesity and diabetes continue to expand. Hence, as hyperglycemia is a defining feature of diabetes, it is logical to probe the impact of the specific consequences of hyperglycemia on the vessel wall, immune cell perturbation, and endothelial dysfunction-all harbingers to the development of CVD. In this context, high levels of blood glucose stimulate the formation of the irreversible advanced glycation end products, the products of non-enzymatic glycation and oxidation of proteins and lipids. AGEs accumulate in diabetic circulation and tissues and the interaction of AGEs with their chief cellular receptor, receptor for AGE or RAGE, contributes to vascular and immune cell perturbation. The cytoplasmic domain of RAGE lacks endogenous kinase activity; the discovery that this intracellular domain of RAGE binds to the formin, DIAPH1, and that DIAPH1 is essential for RAGE ligand-mediated signal transduction, identifies the specific cellular means by which RAGE functions and highlights a new target for therapeutic interruption of RAGE signaling. In human subjects, prominent signals for RAGE activity include the presence and levels of two forms of soluble RAGE, sRAGE, and endogenous secretory (es) RAGE. Further, genetic studies have revealed single nucleotide polymorphisms (SNPs) of the AGER gene (AGER is the gene encoding RAGE) and DIAPH1, which display associations with CVD. This Review presents current knowledge regarding the roles for RAGE and DIAPH1 in the causes and consequences of diabetes, from obesity to CVD. Studies both from human subjects and animal models are presented to highlight the breadth of evidence linking RAGE and DIAPH1 to the cardiovascular consequences of these metabolic disorders.

Pyridostigmine regulates glucose metabolism and mitochondrial homeostasis to reduce myocardial vulnerability to injury in diabetic mice

Diabetic patients are more susceptible to myocardial ischemia damage than nondiabetic patients, with worse clinical outcomes and greater mortality. The mechanism may be related to glucose metabolism, mitochondrial homeostasis, and oxidative stress. Pyridostigmine may improve vagal activity to protect cardiac function in cardiovascular diseases. Researchers have not determined whether pyridostigmine regulates glucose metabolism and mitochondrial homeostasis to reduce myocardial vulnerability to injury in diabetic mice. In the present study, autonomic imbalance, myocardial damage, mitochondrial dysfunction, and oxidative stress were exacerbated in isoproterenol-stimulated diabetic mice, revealing the myocardial vulnerability of diabetic mice to injury compared with mice with diabetes or exposed to isoproterenol alone. Compared with normal mice, the expression of glucose transporters (GLUT)1/4 phosphofructokinase (PFK) FB3, and pyruvate kinase isoform (PKM) was decreased in diabetic mice, but increased in isoproterenol-stimulated normal mice. Following exposure to isoproterenol, the expression of (GLUT)1/4 phosphofructokinase (PFK) FB3, and PKM decreased in diabetic mice compared with normal mice. The downregulation of SIRT3/AMPK and IRS-1/Akt in isoproterenol-stimulated diabetic mice was exacerbated compared with that in diabetic mice or isoproterenol-stimulated normal mice. Pyridostigmine improved vagus activity, increased GLUT1/4, PFKFB3, and PKM expression, and ameliorated mitochondrial dysfunction and oxidative stress to reduce myocardial damage in isoproterenol-stimulated diabetic mice. Based on these results, it was found that pyridostigmine may reduce myocardial vulnerability to injury via the SIRT3/AMPK and IRS-1/Akt pathways in diabetic mice with isoproterenol-induced myocardial damage. This study may provide a potential therapeutic target for myocardial damage in diabetic patients.

Deficiency of S100B confers resistance to experimental diabetes in mice

The calcium binding protein S100B has been implicated in diabetic neuronal and vascular complications but has not been examined in the development of diabetes. S100B knock out (S100B KO) and wild-type (WT) mice were injected with 40 mg/kg body weight streptozotocin (STZ) for 5 days. Blood and pancreatic tissue samples were obtained to examine islet structure and function, the profile of glucose and insulin and expression of glucose transporter 2 (Glut2), S100B and its receptor, the receptor for advanced glycation end products (RAGE). Primary islet β-cells cultures from WT mice were used to test the apoptotic potential of S100B. S100B KO mice were resistant to STZ induced-diabetes with lower urine volume, food and water intake compared to WT mice. S100B increased in the WT islet following diabetes but did not co-localize with beta or peri-islet Schwann cells but with CD3 + T lymphocytes. S100B KO mice exhibited enhanced glucose tolerance, insulin sensitivity, prevented β-cell destruction and functional impairment in response to STZ treatment. S100B deficiency was associated with decreased Glut2 and RAGE. In primary β-cell cultures from WT mice, S100B induced reactive oxygen species (ROS) and RAGE-dependent apoptosis. In the STZ diabetic animal model, abrogation of S100B enhances insulin sensitivity and reduces pancreatic islet, and β-cell destruction. S100B may be a promising target for pharmacological interventions aimed at repressing diabetes.

S100B protein in tissue development, repair and regeneration

The Ca²⁺-binding protein of the EF-hand type, S100B, exerts both intracellular and extracellular regulatory activities. As an intracellular regulator, S100B is involved in the regulation of energy metabolism, transcription, protein phosphorylation, cell proliferation, survival, differentiation and motility, and Ca²⁺ homeostasis, by interacting with a wide array of proteins (i.e., enzymes, enzyme substrates, cytoskeletal subunits, scaffold/adaptor proteins, transcription factors, ubiquitin E3 ligases, ion channels) in a restricted number of cell types. As an extracellular signal, S100B engages the pattern recognition receptor, receptor for advanced glycation end-products (RAGE), on immune cells as well as on neuronal, astrocytic and microglial cells, vascular smooth muscle cells, skeletal myoblasts and cardiomyocytes. However, RAGE may not be the sole receptor activated by S100B, the protein being able to enhance bFGF-FGFR1 signaling by interacting with FGFR1-bound bFGF in particular cell types. Moreover, extracellular effects of S100B vary depending on its local concentration. Increasing evidence suggests that at the concentration found in extracellular fluids in normal physiological conditions and locally upon acute tissue injury, which is up to a few nM levels, S100B exerts trophic effects in the central and peripheral nervous system and in skeletal muscle tissue thus participating in tissue homeostasis. The present commentary summarizes results implicating intracellular and extracellular S100B in tissue development, repair and regeneration.