The role of inflammation in the pathogenesis and treatment of arrhythmias

Unraveling the complex interplay between Mitochondria-Associated Membranes (MAMs) and cardiovascular Inflammation: Molecular mechanisms and therapeutic implications

Cardiovascular diseases (CVDs) represent a significant public health concern because of their associations with inflammation, oxidative stress, and abnormal remodeling of the heart and blood vessels. In this review, we discuss the intricate interplay between mitochondria-associated membranes (MAMs) and cardiovascular inflammation, highlighting their role in key cellular processes such as calcium homeostasis, lipid metabolism, oxidative stress management, and ERS. We explored how these functions impact the pathogenesis and progression of various CVDs, including myocardial ischemia-reperfusion injury, atherosclerosis, diabetic cardiomyopathy, cardiovascular aging, heart failure, and pulmonary hypertension. Additionally, we examined current therapeutic strategies targeting MAM-related pathways and proteins, emphasizing the potential of MAMs as therapeutic targets. Our review aims to provide new insights into the mechanisms of cardiovascular inflammation and propose novel therapeutic approaches to improve cardiovascular health outcomes.

Advancing drug development for atrial fibrillation by prioritising findings from human genetic association studies

BACKGROUND

Drug development for atrial fibrillation (AF) has failed to yield new approved compounds. We sought to identify and prioritise potential druggable targets with support from human genetics, by integrating the available evidence with bioinformatics sources relevant for AF drug development.

METHODS

Genetic hits for AF and related traits were identified through structured search of MEDLINE. Genes derived from each paper were cross-referenced with the OpenTargets platform for drug interactions. Confirmation/validation was demonstrated through structured searches and review of evidence on MEDLINE and ClinialTrials.gov for each drug and its association with AF.

FINDINGS

613 unique drugs were identified, with 21 already included in AF Guidelines. Cardiovascular drugs from classes not currently used for AF (e.g. ranolazine and carperitide) and anti-inflammatory drugs (e.g. dexamethasone and mehylprednisolone) had evidence of potential benefit. Further targets were considered druggable but remain open for drug development.

INTERPRETATION

Our systematic approach, combining evidence from different bioinformatics platforms, identified drug repurposing opportunities and druggable targets for AF.

FUNDING

KK is supported by Barts Charity grant G-002089 and is mentored on the AFGen 2023-24 Fellowship funded by the AFGen NIH/NHLBI grant R01HL092577. RP is supported by the UCL BHF Research Accelerator AA/18/6/34223 and NIHR grant NIHR129463. AFS is supported by the BHF grants PG/18/5033837, PG/22/10989 and UCL BHF Accelerator AA/18/6/34223 as well as the UK Research and Innovation (UKRI) under the UK government's Horizon Europe funding guarantee EP/Z000211/1 and by the UKRI-NIHR grant MR/V033867/1 for the Multimorbidity Mechanism and Therapeutics Research Collaboration. AF is supported by UCL BHF Accelerator AA/18/6/34223. CF is supported by UCL BHF Accelerator AA/18/6/34223.

Inflammation-based lung adenocarcinoma molecular subtype identification and construction of an inflammation-related signature with bulk and single-cell RNA-seq data

The role of inflammation is increasingly understood to have a central influence on therapeutic outcomes and prognosis in lung adenocarcinoma (LUAD). However, the detailed molecular divisions involved in inflammatory responses are yet to be fully elucidated. Our study identified two main inflammation-oriented LUAD grades: the inflammation-low (INF-low) and the inflammation-high (INF-high) subtypes. Both presented with unique clinicopathological features, implications for prognosis, and distinctive tumor microenvironment profiles. Broadly, the INF-low grade, marked by its dominant immunosuppressive tumor microenvironment, was accompanied by less favorable prognostic outcomes and a heightened prevalence of oncogenic mutations. In contrast, the INF-high grade exhibited more optimistic clinical trajectories, underscored by its immune-active environment. In addition, our efforts led to the conceptualization and empirical validation of an inflammation-centric predictive model with considerable predictive potency. Our study paves the way for a refined inflammation-centric LUAD classification and fosters a deeper understanding of tumor microenvironment intricacies.

Biomarker Periodic Repolarization Dynamics Indicates Enhanced Risk for Arrhythmias and Sudden Cardiac Death in Myocardial Infarction in Pigs

BACKGROUND

Periodic repolarization dynamics (PRD) is an electrocardiographic biomarker that captures repolarization instability in the low frequency spectrum and is believed to estimate the sympathetic effect on the ventricular myocardium. High PRD indicates an increased risk for postischemic sudden cardiac death (SCD). However, a direct link between PRD and proarrhythmogenic autonomic remodeling has not yet been shown.

METHODS AND RESULTS

We investigated autonomic remodeling in pigs with myocardial infarction (MI)-related ischemic heart failure induced by balloon occlusion of the left anterior descending artery (n=17) compared with pigs without MI (n=11). Thirty days after MI, pigs demonstrated enhanced sympathetic innervation in the infarct area, border zone, and remote left ventricle paralleled by altered expression of autonomic marker genes/proteins. PRD was enhanced 30 days after MI compared with baseline (pre-MI versus post-MI: 1.75±0.30 deg2 versus 3.29±0.79 deg2, P<0.05) reflecting pronounced autonomic alterations on the level of the ventricular myocardium. Pigs with MI-related ventricular fibrillation and SCD had significantly higher pre-MI PRD than pigs without tachyarrhythmias, suggesting a potential role for PRD as a predictive biomarker for ischemia-related arrhythmias (no ventricular fibrillation versus ventricular fibrillation: 1.50±0.39 deg2 versus 3.18±0.53 deg2 [P<0.05]; no SCD versus SCD: 1.67±0.32 deg2 versus 3.91±0.63 deg2 [P<0.01]).

CONCLUSIONS

We demonstrate that ischemic heart failure leads to significant proarrhythmogenic autonomic remodeling. The concomitant elevation of PRD levels in pigs with ischemic heart failure and pigs with MI-related ventricular fibrillation/SCD suggests PRD as a biomarker for autonomic remodeling and as a potential predictive biomarker for ventricular arrhythmias/survival in the context of MI.

Tirzepatide attenuates lipopolysaccharide-induced left ventricular remodeling and dysfunction by inhibiting the TLR4/NF-kB/NLRP3 pathway

BACKGROUNDS

Sepsis-induced cardiac dysfunction is a leading cause of mortality in intensive care units. Tirzepatide, a dual glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptor agonist, possess cardio-protective, their effects on sepsis-induced cardiomyopathy remain unknown.

METHODS

C57BL/6 mice received subcutaneous injections of tirzepatide once a day for 14 days before subjected to LPS challenge for 12 h. LPS-induced cardiac dysfunction and its potential mechanisms were estimated by pathological analysis, echocardiographic measurement, electrocardiography, langendorff-perfused heart and molecular analysis.

RESULTS

Pretreatment with tirzepatide attenuates LPS-induced cardiac dysfunction. tirzepatide remarkably reduces LPS-mediated inflammatory responses by inhibiting  the cardiac protein levels of TNF-α, IL-6, and IL-1B in mice. Interestingly, tirzepatide administration also improves cardiomyocytes apoptosis caused by LPS treatment. Furthermore, the protective roles of irzepatide against LPS-mediated increased inflammatory responses and decreased cardiomyocytes apoptosis are partially blunted by inhibiting TLR4/NF-kB/NLRP3 inflammation signaling. In addition, tirzepatide reduce the susceptibility ventricular arrhythmia in LPS-treated mice.

CONCLUSION

In brief, tirzepatide attenuates LPS-induced left ventricular remodeling and dysfunction by inhibiting the TLR4/NF-kB/NLRP3 pathway.

Formulated chitosan-sodium tripolyphosphate nanoparticles for co-encapsulation of ellagic acid and anti-inflammatory peptide: characterization, stability and anti-inflammatory activity

BACKGROUND

Chitosan (CS) and tripolyphosphate (TPP) can be combined in the development of a material with synergistic properties and promising potential for the conservation of food products. In this study, ellagic acid (EA) and anti-inflammatory peptide (FPL)-loaded CS nanoparticles (FPL/EA NPs) were prepared using the ionic gelation method and optimal preparation conditions were obtained through a single factor design.

RESULTS

The synthesized nanoparticles (NPs) were characterized using a scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). Nanoparticles were spherical, with an average size of 308.33 ± 4.61 nm, a polydispersity index (PDI) of 0.254, a zeta potential of +31.7 ± 0.08 mV, and a high encapsulation capacity (22.16 ± 0.79%). An in vitro release study showed that EA/FPL had a sustainable release from FPL/EA NPs. The stability of the FPL/EA NPs was evaluated for 90 days at 0, 25, and 37 °C. Significant anti-inflammatory activity of FPL/EA NPs was verified by nitric oxide (NO) and tumor necrosis factor-α (TNF-α) reduction.

CONCLUSION

These characteristics support the use of CS nanoparticles to encapsulate EA and FPL and improve their bioactivity in food products. © 2023 Society of Chemical Industry.

Monotropein attenuates doxorubicin-induced oxidative stress, inflammation, and arrhythmia via the AKT signal pathway

As a glycoside iridoid, monotropein (MON) has a wide range of pharmacological properties, including anti-inflammatory, antioxidant, and anti-apoptotic effects. However, few studies have investigated MON's cardiovascular protective effects. Therefore, this study aimed to explore the role of MON in doxorubicin (DOX)-induced cardiotoxicity. To establish the myocardial toxicity model, mice were intraperitoneally injected with DOX. After admimistration of DOX, myocardial injury markers were increased, cardiac function was reduced, and pathological changes were observed in the myocardium, indicating successful construction of the myocardial injury model. Our study showed that MON treatment mitigated DOX-induced myocardial damage and improved cardiac dysfunction. In addition, DOX-treated mice displayed higher levels of inflammation and oxidative stress, while MON treatment also reversed these pathological changes. Moreover, DOX-treated mice were more susceptible to ventricular fibrillation, whereas MON reduced ventricular fibrillation incidence. Further studies have shown that MON could reverse DOX-induced inhibition of the AKT signaling pathway. Besides, the application of AKT inhibitor could partially abolish MON's cardioprotective effects. To conclude, this study demonstrated the ability of MON to reduce DOX-induced myocardial damage, cardiac dysfunction, inflammation, and oxidative stress, as well as ventricular fibrillation risk. These may attributable to the activation of the AKT pathway.

Radiofrequency Ablation in Patients Undergoing Mitral Valve Surgery with or without Giant Left Atria

Purpose: We aimed to compare the efficacy of radiofrequency ablation (RFA) in patients undergoing mitral valve (MV) surgery with or without giant left atria.

Methods: This retrospective, single-center, cohort study investigated patients who underwent MV surgery and concomitant RFA from 2009 to 2019. Patients were divided into non-giant left atria (diameter ≤65 mm, n = 1543) and giant left atria (diameter >65 mm, n = 241) groups. Five-year freedom from atrial tachyarrhythmia recurrence and thromboembolic event (TE) rates were assessed with death as the competing risk factor with and without propensity-score matching.

Results: Patients with giant left atria had higher mortality (10.8% versus 6.2%, P = 0.008) and readmission rates for heart failure than those without (12.0% versus 6.8%, P = 0.004). Atrial tachyarrhythmia recurrence rates were higher in patients with giant left atria than in those without (49% versus 24% at 5 years, P <0.001), but the cumulative incidence of TEs before (P = 0.944) and after (P = 0.695) propensity-score matching was comparable.

Conclusions: RFA effectively prevented TEs in patients with giant left atria, despite significant atrial tachyarrhythmia recurrence. Atrial tachyarrhythmia recurrence did not increase the risk of TEs. A lower success rate should be considered when deciding whether to perform surgical ablation in patients with giant left atria.

Mechanistic Insights Into Inflammation-Induced Arrhythmias: A Simulation Study

Cardiovascular diseases are the primary cause of death of humans, and among these, ventricular arrhythmias are the most common cause of death. There is plausible evidence implicating inflammation in the etiology of ventricular fibrillation (VF). In the case of systemic inflammation caused by an overactive immune response, the induced inflammatory cytokines directly affect the function of ion channels in cardiomyocytes, leading to a prolonged action potential duration (APD). However, the mechanistic links between inflammatory cytokine-induced molecular and cellular influences and inflammation-associated ventricular arrhythmias need to be elucidated. The present study aimed to determine the potential impact of systemic inflammation on ventricular electrophysiology by means of multiscale virtual heart models. The experimental data on the ionic current of three major cytokines [i.e., tumor necrosis factor-α (TNF-α), interleukin-1 (IL-1β), and interleukin-6 (IL-6)] were incorporated into the cell model, and the effects of each cytokine and their combined effect on the cell action potential (AP) were evaluated. Moreover, the integral effect of these cytokines on the conduction of excitation waves was also investigated in a tissue model. The simulation results suggested that inflammatory cytokines significantly prolonged APD, enhanced the transmural and regional repolarization heterogeneities that predispose to arrhythmias, and reduced the adaptability of ventricular tissue to fast heart rates. In addition, simulated pseudo-ECGs showed a prolonged QT interval—a manifestation consistent with clinical observations. In summary, the present study provides new insights into ventricular arrhythmias associated with inflammation.