Primary Human Cardiomyocytes and Cardiofibroblasts Treated with Sera from Myocarditis Patients Exhibit an Increased Iron Demand and Complex Changes in the Gene Expression

Myocarditis: A multi-omics approach

Myocarditis, an inflammatory condition of weakened heart muscles often triggered by a variety of causes, that can result in heart failure and sudden death. Novel ways to enhance our understanding of myocarditis pathogenesis is available through newer modalities (omics). In this review, we examine the roles of various biomolecules and associated functional pathways across genomics, transcriptomics, proteomics, and metabolomics in the pathogenesis of myocarditis. Our analysis further explores the reproducibility and variability intrinsic to omics studies, underscoring the necessity and significance of employing a multi-omics approach to gain profound insights into myocarditis pathogenesis. This integrated strategy not only enhances our understanding of the disease, but also confirms the critical importance of a holistic multi-omics approach in disease analysis.

Interaction between systemic iron parameters and left ventricular structure and function in the preserved ejection fraction population: a two-sample bidirectional Mendelian randomization study

BACKGROUND

Left ventricular (LV) remodeling and diastolic function in people with heart failure (HF) are correlated with iron status; however, the causality is uncertain. This Mendelian randomization (MR) study investigated the bidirectional causal relationship between systemic iron parameters and LV structure and function in a preserved ejection fraction population.

METHODS

Transferrin saturation (TSAT), total iron binding capacity (TIBC), and serum iron and ferritin levels were extracted as instrumental variables for iron parameters from meta-analyses of public genome-wide association studies. Individuals without myocardial infarction history, HF, or LV ejection fraction (LVEF) < 50% (n = 16,923) in the UK Biobank Cardiovascular Magnetic Resonance Imaging Study constituted the outcome dataset. The dataset included LV end-diastolic volume, LV end-systolic volume, LV mass (LVM), and LVM-to-end-diastolic volume ratio (LVMVR). We used a two-sample bidirectional MR study with inverse variance weighting (IVW) as the primary analysis method and estimation methods using different algorithms to improve the robustness of the results.

RESULTS

In the IVW analysis, one standard deviation (SD) increased in TSAT significantly correlated with decreased LVMVR (β = -0.1365; 95% confidence interval [CI]: -0.2092 to -0.0638; P = 0.0002) after Bonferroni adjustment. Conversely, no significant relationships were observed between other iron and LV parameters. After Bonferroni correction, reverse MR analysis showed that one SD increase in LVEF significantly correlated with decreased TSAT (β = -0.0699; 95% CI: -0.1087 to -0.0311; P = 0.0004). No heterogeneity or pleiotropic effects evidence was observed in the analysis.

CONCLUSIONS

We demonstrated a causal relationship between TSAT and LV remodeling and function in a preserved ejection fraction population.

Comparison of the Protective Effects of Nebivolol and Metoprolol against LPS-Induced Injury in H9c2 Cardiomyoblasts

Here, we, for the first time, compared the cardioprotective effects of third-generation vasodilating beta-blocker nebivolol (Neb) and conventional beta-blocker metoprolol (Met) on LPS-induced injury in H9c2 cardiomyoblasts. Our findings denoted that Neb and Met pretreatment diminish LPS-mediated cytotoxicity and oxidative stress. Concomitantly, LPS-triggered inflammatory cytokines activation was significantly suppressed by Neb but not by Met. Pretreatment with either Neb or Met alleviated LPS-mediated mitochondrial impairment by enhancing the expression of genes related to its biogenesis such as PGC-1α, NRF1, and TFAM. On the contrary, Neb but not Met-upregulated mitochondrial fusion-related genes such as OPA, and MFN2. In summary, our findings suggest that Neb and Met treatment significantly ameliorated the LPS-induced cytotoxicity and oxidative stress. Additionally, these findings suggest that Neb but not Met significantly down-regulates LPS-induced proinflammatory factors, probably by enhancing mitochondrial biogenesis and fusion.

Intravenous iron supplementation improves energy metabolism of exercising skeletal muscles without effect on either oxidative stress or inflammation in male patients with heart failure with reduced ejection fraction

BACKGROUND

Skeletal muscle dysfunction is a feature of heart failure (HF). Iron deficiency (ID) is prevalent in patients with HF associated with exercise intolerance and poor quality of life. Intravenous iron in iron deficient patients with HF has attenuated HF symptoms, however the pathomechanisms remain unclear. The aim of study was to assess whether intravenous iron supplementation as compared to placebo improves energy metabolism of skeletal muscles in patients with HF.

METHODS

Men with heart failure with reduced ejection fraction (HFrEF) and ID were randomised in 1:1 ratio to either intravenous ferric carboxymaltose (IV FCM) or placebo. In vivo reduction of lactates by exercising skeletal muscles of forearm was analyzed. A change in lactate production between week 0 and 24 was considered as a primary endpoint of the study.

RESULTS

There were two study arms: the placebo and the IV FCM (12 and 11 male patients with HFrEF). At baseline, there were no differences between these two study arms. IV FCM therapy as compared to placebo reduced the exertional production of lactates in exercising skeletal muscles. These effects were accompanied by a significant increase in both serum ferritin and transferrin saturation in the IV FCM arm which was not demonstrated in the placebo arm.

CONCLUSIONS

Intravenous iron supplementation in iron deficient men with HFrEF improves the functioning of skeletal muscles via an improvement in energy metabolism in exercising skeletal muscles, limiting the contribution of anaerobic reactions generating ATP as reflected by a lower in vivo lactate production in exercising muscles in patients with repleted iron stores.

Role of Coxsackievirus B3-Induced Immune Responses in the Transition from Myocarditis to Dilated Cardiomyopathy and Heart Failure

Dilated cardiomyopathy (DCM) is a cardiac disease marked by the stretching and thinning of the heart muscle and impaired left ventricular contractile function. While most patients do not develop significant cardiac diseases from myocarditis, disparate immune responses can affect pathological outcomes, including DCM progression. These altered immune responses, which may be caused by genetic variance, can prolong cytotoxicity, induce direct cleavage of host protein, or encourage atypical wound healing responses that result in tissue scarring and impaired mechanical and electrical heart function. However, it is unclear which alterations within host immune profiles are crucial to dictating the outcomes of myocarditis. Coxsackievirus B3 (CVB3) is a well-studied virus that has been identified as a causal agent of myocarditis in various models, along with other viruses such as adenovirus, parvovirus B19, and SARS-CoV-2. This paper takes CVB3 as a pathogenic example to review the recent advances in understanding virus-induced immune responses and differential gene expression that regulates iron, lipid, and glucose metabolic remodeling, the severity of cardiac tissue damage, and the development of DCM and heart failure.

Cardiovascular Complications of Viral Respiratory Infections and COVID-19

Viral respiratory infections (VRI) are the most prevalent type of infectious diseases and constitute one of the most common causes of contact with medical care. Regarding the pathophysiology of the cardiovascular system, VRI can not only exacerbate already existing chronic cardiovascular disease (such as coronary artery disease or heart failure) but also trigger new adverse events or complications (e.g., venous thromboembolism), the latter particularly in subjects with multimorbidity or disease-related immobilization. In the current paper, we provide a narrative review of diverse cardiovascular complications of VRI as well as summarize available data on the pathology of the circulatory system in the course of coronavirus disease 2019 (COVID-19).

Aberrant Transferrin and Ferritin Upregulation Elicits Iron Accumulation and Oxidative Inflammaging Causing Ferroptosis and Undermines Estradiol Biosynthesis in Aging Rat Ovaries by Upregulating NF-Κb-Activated Inducible Nitric Oxide Synthase: First Demonstration of an Intricate Mechanism

We report herein a novel mechanism, unraveled by proteomics and validated by in vitro and in vivo studies, of the aberrant aging-associated upregulation of ovarian transferrin and ferritin in rat ovaries. The ovarian mass and serum estradiol titer plummeted while the ovarian labile ferrous iron and total iron levels escalated with age in rats. Oxidative stress markers, such as nitrite/nitrate, 3-nitrotyrosine, and 4-hydroxy-2-nonenal, accumulated in the aging ovaries due to an aberrant upregulation of the ovarian transferrin, ferritin light/heavy chains, and iron regulatory protein 2(IRP2)-mediated transferrin receptor 1 (TfR1). Ferritin inhibited estradiol biosynthesis in ovarian granulosa cells in vitro via the upregulation of a nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and p65/p50-induced oxidative and inflammatory factor inducible nitric oxide synthase (iNOS). An in vivo study demonstrated how the age-associated activation of NF-κB induced the upregulation of iNOS and the tumor necrosis factor α (TNFα). The downregulation of the keap1-mediated nuclear factor erythroid 2-related factor 2 (Nrf2), that induced a decrease in glutathione peroxidase 4 (GPX4), was observed. The aberrant transferrin and ferritin upregulation triggered an iron accumulation via the upregulation of an IRP2-induced TfR1. This culminates in NF-κB-iNOS-mediated ovarian oxi-inflamm-aging and serum estradiol decrement in naturally aging rats. The iron accumulation and the effect on ferroptosis-related proteins including the GPX4, TfR1, Nrf2, Keap1, and ferritin heavy chain, as in testicular ferroptosis, indicated the triggering of ferroptosis. In young rats, an intraovarian injection of an adenovirus, which expressed iron regulatory proteins, upregulated the ovarian NF-κB/iNOS and downregulated the GPX4. These novel findings have contributed to a prompt translational research on the ovarian aging-associated iron metabolism and aging-associated ovarian diseases.

TFRC upregulation promotes ferroptosis in CVB3 infection via nucleus recruitment of Sp1

CVB3 is a single positive-strand enterovirus, and a common pathogen in myocarditis etiology. Although a number of antiviral candidates are under development, specific targeted therapy is not available for CVB3. Ferroptosis is a new type of regulatory cell death discovered in recent years. In this study, our team provided the first evidence that ferroptosis existed in CVB3 infection in vivo and in vitro by iron overload, and massive accumulation of lipid peroxides. Mechanistically, we construct a classical model of HeLa cells following a time-course infection (6, 12, 24, 36, 48 h) with CVB3 (MOI = 10). We demonstrated that the TFRC gene plays an important role in promoting ferroptosis in CVB3 infection and downregulation of TFRC attenuated the ferroptosis. Interestingly, we observed that TFRC was nuclear translocation induced by the CVB3, which was predominantly localized in the cell membrane, but redistributed to the nucleus during CVB3 infection. Moreover, we found that the transcription factor Sp1 was an essential factor that could bind to the TFRC promoter and upregulate the TFRC transcription. Collectively, these results suggest that the Sp1/TFRC/Fe axis may provide a new target for the development of therapies against CVB3 infection.