Expanding the Frontiers of Guardian Antioxidant Selenoproteins in Cardiovascular Pathophysiology

Selenoprotein P predicting mortallity in acute ill patients with dyspnea

BACKGROUND AND AIMS

Good Selenium (Se) status predicts favorable prognoses for various diseases and a reduced overall mortality. The primary objective of the study was to determine whether Selenium status, i.e. Selenoprotein P (SeP) levels, is associated with risk of 90-day mortality in elderly patients with acute dyspnea at the Emergency Department (ED).

METHODS AND RESULTS

Patients presenting with dyspnea were enrolled from the ED at the University Hospital in Malmö between 2013 and 2018. Cox regression analyses were conducted to evaluate hazard ratios (HRs) for 90-day mortality. This analysis was performed in two steps. Model A included adjustments for age and sex with 95 % confidence intervals (95 % CI) for individual factors such as SeP levels, the Medical Emergency Triage and Treatment System - Adult (METTS-A), BMI levels, comorbidities, and smoking status. Model B was a multivariate analysis with 99 % confidence intervals (99 % CI), incorporating age, sex, and statistically significant factors from Model A, including SeP levels, BMI, heart failure, anemia, and stroke. A lower concentration of SeP was independently associated with a higher risk of death within 90 days. In the continuous model of SeP, the HR was 0.798 (99 % CI 0.678-0.940). When comparing the lowest quartile to the highest quartile of SeP, the HR was 2.462 (99 % CI 1.240-4.891).

CONCLUSION

Low SeP concentrations were found to predict 90-day mortality in ED patients presenting with dyspnea. The assessment of SeP levels could serve as a valuable tool in the initial evaluation of elderly patients in the ED.

Interspecies differences in mitochondria: Implications for cardiac and vascular translational research

Mitochondria are essential organelles that regulate cellular energy metabolism, redox balance, and signaling pathways related to proliferation, aging and survival. So far, significant interspecies differences exist in mitochondrial structure, function, and dynamics, which have critical implications for cardiovascular physiology and pharmacology. This review explores the main differences in mitochondrial properties across species of animals that are commonly used for translational research, emphasizing their cardiac and vascular relevance. By addressing key interspecies differences, including mitochondrial DNA (mtDNA) variation, bioenergetic profile, oxidative stress response, epigenetic regulation, mitochondrial biogenesis, and adaptive mechanisms, we aim to provide insights into the challenges and opportunities in translating preclinical findings to clinical applications. Understanding these interspecies differences is essential for optimizing the design and interpretation of preclinical studies and for developing effective mitochondrial-targeted therapies.

Elucidating emerging signaling pathways driving endothelial dysfunction in cardiovascular aging

The risk for developing cardiovascular diseases dramatically increases in older individuals, and aging vasculature plays a crucial role in determining their morbidity and mortality. Aging disrupts endothelial balance between vasodilators and vasoconstrictors, impairing function and promoting pathological vascular remodeling. In this Review, we discuss the impact of key and emerging molecular pathways that transduce aberrant inflammatory signals (i.e., chronic low-grade inflammation-inflammaging), oxidative stress, and mitochondrial dysfunction in aging vascular compartment. We focus on the interplay between these events, which contribute to generating a vicious cycle driving the progressive alterations in vascular structure and function during cardiovascular aging. We also discuss the primary role of senescent endothelial cells and vascular smooth muscle cells, and the potential link between vascular and myeloid cells, in impairing plaque stability and promoting the progression of atherosclerosis. The aim of this summary is to provide potential novel insights into targeting these processes for therapeutic benefit.

Mitochondrial quality control: Biochemical mechanism of cardiovascular disease

Mitochondria play a key role in the regulation of energy homeostasis and ATP production in cardiac cells. Mitochondrial dysfunction can trigger several pathological events that contribute to the development and progression of cardiovascular diseases. These mechanisms include the induction of oxidative stress, dysregulation of intracellular calcium cycling, activation of the apoptotic pathway, and alteration of lipid metabolism. This review focuses on the role of mitochondria in intracellular signaling associated with cardiovascular diseases, emphasizing the contributions of reactive oxygen species production and mitochondrial dynamics. Indeed, mitochondrial dysfunction has been implicated in every aspect of cardiovascular disease and is currently being evaluated as a potential target for therapeutic interventions. To treat cardiovascular diseases and improve overall heart health, it is important to better understand these biochemical systems. These findings allow the achievement of targeted therapies and preventive measures. Therefore, this review investigates different studies that demonstrate how changes in mitochondrial dynamics like fusion, fission, and mitophagy contribute to the development or worsening of disorders related to heart diseases by summarizing current research on their role.

A recombinant fragment antigen-binding (Fab) of trastuzumab displays low cytotoxic profile in adult human cardiomyocytes: first evidence and the key implication of FcγRIIA receptor

Fragment crystallizable gamma receptors (FcγRs) mediate various cellular responses with significant cardiovascular implications. They contribute to the anticancer activity of trastuzumab (TRZ), a recombinant humanized monoclonal antibody that interferes with human epidermal growth factor receptor 2 (HER2), thereby blocking its physiological function in cardiac cells. This is responsible for cardiac complications that hamper TRZ clinical application. In this study we investigated the involvement of FcγRs in the TRZ cardiotoxicity. We used a recombinant antigen-binding fragment (Fab) of TRZ (rFab-HER2) to examine whether the absence of the Fc region resulted in fewer cardiomyocyte toxicity while preserving TRZ's ability to inhibit HER2. When exposed to rFab-HER2, AC16 human adult ventricular cardiomyocytes were less vulnerable to damage and death, than to TRZ. Specifically, TRZ exhibited cytotoxicity at a lower concentration (150 µg/mL, corresponding to ~1 µM) compared to rFab-HER2 (250 µg/mL, corresponding to ~5 µM). Like TRZ, rFab-HER2 negatively modulated HER2 levels in cardiomyocyte (without inducing cytotoxic activity in BJ human fibroblast cells that either did not express or express very low levels of HER2) and inhibited the downstream ERK/AKT cascades. But rFab-HER2 did not alter cardiomyocyte mitochondrial dynamic balance, and affect apoptosis and inflammation, while it limited cytosolic and mitochondrial ROS indicators. On contrary, the Fc region (50-250 μg/mL) exerted direct cytotoxic action on cardiomyocytes (but not on human fibroblasts that lacked Fc receptors). TRZ (150 μg/mL) markedly upregulated the expression level of FcγRIIA (a FcγRs strongly involved in TRZ-induced antibody-dependent cellular toxicity) in cardiomyocytes, whereas the Fab fragment (150 μg/mL) had no effect. Our results demonstrate that Fc region plays an important pathogenic role in TRZ-induced cardiomyocyte toxicity. In addition, targeting FcγRIIA might contribute to the off-target effects of TRZ therapy.

Endothelial Dysfunction: Redox Imbalance, NLRP3 Inflammasome, and Inflammatory Responses in Cardiovascular Diseases

Endothelial dysfunction (ED) is characterized by an imbalance between vasodilatory and vasoconstrictive factors, leading to impaired vascular tone, thrombosis, and inflammation. These processes are critical in the development of cardiovascular diseases (CVDs) such as atherosclerosis, hypertension and ischemia/reperfusion injury (IRI). Reduced nitric oxide (NO) production and increased oxidative stress are key contributors to ED. Aging further exacerbates ED through mitochondrial dysfunction and increased oxidative/nitrosative stress, heightening CVD risk. Antioxidant systems like superoxide-dismutase (SOD), glutathione-peroxidase (GPx), and thioredoxin/thioredoxin-reductase (Trx/TXNRD) pathways protect against oxidative stress. However, their reduced activity promotes ED, atherosclerosis, and vulnerability to IRI. Metabolic syndrome, comprising insulin resistance, obesity, and hypertension, is often accompanied by ED. Specifically, hyperglycemia worsens endothelial damage by promoting oxidative stress and inflammation. Obesity leads to chronic inflammation and changes in perivascular adipose tissue, while hypertension is associated with an increase in oxidative stress. The NLRP3 inflammasome plays a significant role in ED, being triggered by factors such as reactive oxygen and nitrogen species, ischemia, and high glucose, which contribute to inflammation, endothelial injury, and exacerbation of IRI. Treatments, such as N-acetyl-L-cysteine, SGLT2 or NLRP3 inhibitors, show promise in improving endothelial function. Yet the complexity of ED suggests that multi-targeted therapies addressing oxidative stress, inflammation, and metabolic disturbances are essential for managing CVDs associated with metabolic syndrome.

Selenoprotein P as a prognostic biomarker of burn sepsis: A prospective cohort study

INTRODUCTION

Severely burned patients exhibit increased nutritional requirements and are at high risk of developing sepsis. Selenium is an essential trace element supporting antioxidant and anti-inflammatory pathways, mediated by incorporation into selenoproteins. The selenium status may affect sepsis risk in burn injury.

METHODS

This prospective cohort study included 90 adult patients admitted to Zurich Burn Center, Switzerland. All patients received a continuous intravenous infusion of 1000 μg sodium selenite per day during the first week as part of local standard of care. Three complementary biomarkers of serum selenium status were determined at nine time-points up to six months postburn, namely total selenium, selenoprotein P, and glutathione peroxidase 3. The resulting data were correlated to clinical parameters and outcomes, with sepsis as the primary end point.

RESULTS

A high fraction of the patients displayed selenium deficiency already at admission, and developed sepsis during hospitalization (n = 55; 61 %). Selenium status at admission was inversely related to burn severity. Low baseline selenoprotein P was associated with sepsis incidence, irrespective of trauma severity (adjusted HR, 1.94; 95 % CI, 1.05-3.63; p = 0.035). Burn severity and baseline concentrations of selenoprotein P and white blood cells together predicted sepsis with an area under the curve of 0.84 (95 % CI, 0.75-0.93; p < 0.0001). Supplemental selenium was associated with a transient normalization of selenium status.

CONCLUSION

Considering its rapid decline following severe burn injury, the assessment of serum selenoprotein P upon admission may contribute to an early prediction of sepsis risk.

Adherence to the Mediterranean diet and its protective effects against colorectal cancer: a meta-analysis of 26 studies with 2,217,404 participants

Colorectal cancer (CRC) is a major global health concern and represents a significant public health challenge in Hungary, where it exhibits some of the highest morbidity and mortality rates in the European Union. The Mediterranean diet has been suggested to reduce the incidence of CRC, but comprehensive evidence from diverse study designs is needed to substantiate this effect. A systematic literature search was conducted in PubMed, ClinicalTrials.gov, CENTRAL, and the Web of Science to identify randomized controlled trials and human clinical trials from 2008 to 2024 to identify relevant studies. Statistical analysis was performed using the https://metaanalysisonline.com web application using a random effects model to estimate the pooled hazard rates (HRs). Forest plots, funnel plots, and Z-score plots were utilized to visualize results. We identified 15 clinical trials and 9 case-control studies, encompassing a total of 2,217,404 subjects. The pooled analysis indicated that adherence to the Mediterranean diet significantly reduced the prevalence of CRC (HR = 0.84, 95% CI = 0.78-0.91, p < 0.01). This protective effect was consistent across sexes, with HRs of 0.85 (95% CI = 0.75-0.97, p = 0.01) for males and 0.88 (95% CI = 0.79-0.99, p = 0.03) for females. Case-control studies specifically showed a substantial effect (HR = 0.51, 95% CI = 0.38-0.68, p < 0.01). Notable heterogeneity was observed across studies, yet the a priori information size was substantially below the cumulative sample size, ensuring sufficient data for reliable conclusions. The findings from this meta-analysis reinforce the protective role of the Mediterranean diet against CRC. The results of this meta-analysis will inform dietary interventions designed to mitigate CRC risk, which are conducted within the framework of the Semmelweis Study, an ongoing comprehensive cohort study at Semmelweis University, designed to explore the multifaceted causes of unhealthy aging in Hungary. These interventions aim to explore the practical application of Mediterranean dietary patterns in reducing CRC incidence among the Hungarian population.

Selenium and Selenoproteins: Mechanisms, Health Functions, and Emerging Applications

Selenium (Se) is an essential trace element crucial for human health that primarily functions as an immunonutrient. It is incorporated into polypeptides such as selenocysteine (SeC) and selenomethionine (SeMet), two key amino acids involved in various biochemical processes. All living organisms can convert inorganic Se into biologically active organic forms, with SeMet being the predominant form and a precursor for SeC production in humans and animals. The human genome encodes 25 selenoprotein genes, which incorporate low-molecular-weight Se compounds in the form of SeC. Organic Se, especially in the form of selenoproteins, is more efficiently absorbed than inorganic Se, driving the demand for selenoprotein-based health products, such as functional foods. Se-enriched functional foods offer a practical means of delivering bioavailable Se and are associated with enhanced antioxidant properties and various health benefits. Recent advancements in selenoprotein synthesis have improved our understanding of their roles in antioxidant defense, cancer prevention, immune regulation, anti-inflammation, hypoglycemia, cardiovascular health, Alzheimer's disease, fertility, and COVID-19. This review highlights key selenoproteins and their biological functions, biosynthetic pathways, and emerging applications while highlighting the need for further research.

Comparative Analysis of the Protective Effect of Naringenin on Cardiovascular Parameters of Normotensive and Hypertensive Rats Subjected to the Myocardial Infarction Model

Background: Cardiovascular diseases rank as the top global cause of mortality, particularly acute myocardial infarction (MI). MI arises from the blockage of a coronary artery, which disrupts blood flow and results in tissue death. Among therapeutic approaches, bioactives from medicinal plants emerge as promising for the development of new medicines. Objectives: This study explored the effects of naringenin (NAR 100 mg/kg), a flavonoid found in citrus fruits, in normotensive (NTR) and spontaneously hypertensive (SHR) rats, both subjected to isoproterenol (ISO 85 mg/kg)-induced MI. Results: Post-treatment assessments indicated that NAR reduced blood pressure and minimized clot formation, particularly notable in the SHR group, which helps mitigate damage related to hypertension and ISO exposure. Additionally, NAR effectively restored KCl-induced contractility in the aortas of both NTR and SHR groups. NAR treatment reduced reduced glutathione (GSH) and lipid hydroperoxides (LOOH) values and recovered the activity of the antioxidant enzymes catalase (CAT) and glutathione-s-transferase (GST) in NTR groups. Moreover, myocardial damage assessed through histological analyses was reduced in groups treated with NAR. Conclusions: The results highlight significant pathophysiological differences between the groups, suggesting that NAR has protective potential against ISO-induced cardiac damage, warranting further investigation into its protective effects and mechanisms.

Metabolic Syndrome, Thyroid Dysfunction, and Cardiovascular Risk: The Triptych of Evil

The triad formed by thyroid dysfunction, metabolic syndrome (MetS), and cardiovascular (CV) risk forms a network with many connections that aggravates health outcomes. Thyroid hormones (THs) play an important role in glucose and lipid metabolism and hemodynamic regulation at the molecular level. It is noteworthy that a bidirectional association between THs and MetS and their components likely exists as MetS leads to thyroid dysfunction, whereas thyroid alterations may cause a higher incidence of MetS. Thyroid dysfunction increases insulin resistance, the circulating levels of lipids, in particular LDL-C, VLDL-C, and triglycerides, and induces endothelial dysfunction. Furthermore, THs are important regulators of both white and brown adipose tissue. Moreover, the pathophysiological relationship between MetS and TH dysfunction is made even tighter considering that these conditions are usually associated with inflammatory activation and increased oxidative stress. Therefore, the role of THs takes place starting from the molecular level, then manifesting itself at the clinical level, through an increased risk of CV events in the general population as well as in patients with heart failure or acute myocardial infarction. Thus, MetS is frequently associated with thyroid dysfunction, which supports the need to assess thyroid function in this group, and when clinically indicated, to correct it to maintain euthyroidism. However, there are still several critical points to be further investigated both at the molecular and clinical level, in particular considering the need to treat subclinical dysthyroidism in MetS patients.

The redox-active defensive Selenoprotein T as a novel stress sensor protein playing a key role in the pathophysiology of heart failure

Maladaptive cardiac hypertrophy contributes to the development of heart failure (HF). The oxidoreductase Selenoprotein T (SELENOT) emerged as a key regulator during rat cardiogenesis and acute cardiac protection. However, its action in chronic settings of cardiac dysfunction is not understood. Here, we investigated the role of SELENOT in the pathophysiology of HF: (i) by designing a small peptide (PSELT), recapitulating SELENOT activity via the redox site, and assessed its beneficial action in a preclinical model of HF [aged spontaneously hypertensive heart failure (SHHF) rats] and against isoproterenol (ISO)-induced hypertrophy in rat ventricular H9c2 and adult human AC16 cardiomyocytes; (ii) by evaluating the SELENOT intra-cardiomyocyte production and secretion under hypertrophied stimulation. Results showed that PSELT attenuated systemic inflammation, lipopolysaccharide (LPS)-induced macrophage M1 polarization, myocardial injury, and the severe ultrastructural alterations, while counteracting key mediators of cardiac fibrosis, aging, and DNA damage and restoring desmin downregulation and SELENOT upregulation in the failing hearts. In the hemodynamic assessment, PSELT improved the contractile impairment at baseline and following ischemia/reperfusion injury, and reduced infarct size in normal and failing hearts. At cellular level, PSELT counteracted ISO-mediated hypertrophy and ultrastructural alterations through its redox motif, while mitigating ISO-triggered SELENOT intracellular production and secretion, a phenomenon that presumably reflects the extent of cell damage. Altogether, these results indicate that SELENOT could represent a novel sensor of hypertrophied cardiomyocytes and a potential PSELT-based new therapeutic approach in myocardial hypertrophy and HF.