Intermittent fasting attenuates obesity-related atrial fibrillation via SIRT3-mediated insulin resistance mitigation

Motor protein KIF5B inhibition as a novel strategy of controlled reperfusion against myocardial ischemia/reperfusion injury

Metabolic dysregulation triggered by nutrient influx at reperfusion onset induces reactive oxygen species (ROS) burst and cellular injury, contributing to the detrimental effects observed in ischemia/reperfusion (I/R) injury. Thus, implementing controlled reperfusion emerges as a superior cardioprotective strategy to alleviate reperfusion injury. Kinesin KIF5B transports GLUT4- and CD36-containing vesicles to the plasma membrane, facilizing the import of glucose and fatty acids into cells, suggesting a role in controlled reperfusion. Herein, we aim to investigate its specific role in myocardial I/R injury. By genetic and pharmacological modulation of KIF5B, we investigated its role in myocardial I/R injury both in vivo and in vitro. During reperfusion, a coordinated inhibition of metabolism-related genes and KIF5B expression occurred, probably mitigating the metabolic stress encountered as a compensatory mechanism. Genetic inhibition of KIF5B using AAV9-shRNA attenuated myocardial I/R injury, as evidenced by reduced infarct size, decreased cardiac biomarkers, and reduced cell apoptosis. Additionally, KIF5B inhibition mitigated post-reperfusion oxidative stress and arrhythmias. Mechanistically, concurrent decrease in CD36 membrane translocation following KIF5B ablation post-reperfusion was confirmed by immunofluorescence double staining, and siRNA knockdown of Kif5b inhibited fatty acids uptake in isolated primary neonatal rat cardiomyocytes. Intraperitoneal administration of rose bengal lactone (RBL, 1 mg/kg), a selective inhibitor of KIF5B, was shown to confer cardioprotective effects against myocardial I/R injury. Our findings demonstrate that the inhibition of KIF5B, as a novel strategy of controlled reperfusion, provides cardioprotection against myocardial I/R injury, and highlights the clinical potential of its inhibitor, RBL, to ameliorate reperfusion injury.

Targeted intervention in obesity-associated atrial fibrosis using nanoparticle-loaded fusion protein

The association between obesity and atrial fibrillation (AF) has garnered increasing attention. Obesity is a significant risk factor for cardiovascular diseases and promotes the occurrence of AF through multiple mechanisms. This study aims to explore the molecular mechanisms of obesity-induced AF using GLP-1R/GIPR dual-target agonist fusion protein (Fc) loaded into adipose-derived mesenchymal stem cell (ADSC) exosome-liposome hybrid nanoparticles (LE@Fc NPs). We successfully constructed and purified the Fc, verifying its purity and functional activity through SDS-PAGE and UV absorption spectroscopy. The fusion protein was then loaded into nanovesicles, and their morphology, size, and stability were assessed using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and dynamic light scattering (DLS). In vitro experiments demonstrated that LE@Fc NPs exhibit high fusion efficiency and targeted delivery capability. In vivo experimental results show that LE@Fc NPs significantly inhibit ferroptosis in the epicardial adipose tissue (EAT) of obese mice (iron content: 3.69 ± 0.36 vs. 0.88 ± 0.09), by restoring GSH levels (0.45 ± 0.08 vs. 0.87 ± 0.08) and Gpx4 expression (0.32 ± 0.06 vs. 1.01 ± 0.16), and reducing ROS (12.01 ± 0.95 vs. 2.68 ± 0.17), MDA (3.17 ± 0.29 vs. 0.95 ± 0.09), and 4-HNE (3.74 ± 0.51 vs. 0.91 ± 0.09) levels. Furthermore, LE@Fc NPs treatment significantly improved the inflammatory response (IL-1β: 44.08 ± 3.74 vs. 12.07 ± 0.65, IL-6: 515.59 ± 47.70 vs. 288.43 ± 16.81, MCP-1: 1401.04 ± 194.88 vs. 600.28 ± 45.54, TNF-α: 39.96 ± 2.48 vs. 18.01 ± 0.85). LE@Fc NPs also reduced atrial fibrosis, thereby effectively lowering the incidence of AF. Echocardiography and electrocardiogram monitoring revealed that LE@Fc NPs treatment significantly improved atrial remodeling and reduced the occurrence of AF in obese mice. In addition, LE@Fc NPs significantly improved obesity-induced systemic inflammation and metabolic disorders. In conclusion, LE@Fc NPs show great potential for the treatment of obesity-related AF.

Long-term glucosamine supplementation aggravates atrial fibrillation susceptibility by impairing AMPK signaling

AIMS

Glucosamine, a widely used dietary supplement, has been linked to potential cardiovascular risks, including atrial fibrillation (AF). This study aimed to investigate the effects of long-term glucosamine supplementation on AF susceptibility and the underlying mechanisms.

MATERIALS AND METHODS

C57BL/6 J mice were treated with low-dose (15 mg/kg/day) or high-dose (250 mg/kg/day) glucosamine via drinking water for 6 weeks. AF susceptibility was assessed through transesophageal electrical stimulation. Atrial remodeling was characterized through electrophysiological and echocardiography studies, histological analysis, and molecular examination. AMP-activated protein kinase (AMPK) activator 5-aminoimidazole-4-carboxamide-1-beta-4-ribofuranoside (AICAR) was used to validation the underlying mechanism in mice and isolated neonatal atrial cardiomyocytes.

KEY FINDINGS

Long-term high-dose glucosamine supplementation increased AF susceptibility in mice, as indicated by an elevated AF incidence and duration. Glucosamine induced notable electrical remodeling, evidenced by intra-atrial conduction slowing (P wave duration, amplitude, and area), likely attributable to reduced conduction velocity, as confirmed by two-dimensional electrical mapping. Structural remodeling including increased left atrial weight, cardiomyocyte hypertrophy and fibrosis was evident in the atria of glucosamine-treated mice, despite unaffected cardiac function. Mechanistically, glucosamine suppressed atrial AMPK signaling, leading to lipid and glycogen accumulation. Intriguingly, despite impaired atrial AMPK signaling, high-dose glucosamine improved systemic insulin sensitivity. Pharmacological activation of AMPK with AICAR mitigated glucosamine-induced AF susceptibility and associated pathological changes both in vivo and in vitro.

SIGNIFICANCE

Our findings demonstrate that long-term glucosamine supplementation enhances AF susceptibility, potentially by impairing atrial AMPK signaling, underscoring the importance of caution in the utilization of glucosamine.

Time-restricted feeding improves metabolic syndrome by activating thermogenesis in brown adipose tissue and reducing inflammatory markers

Background

Obesity and metabolic syndrome (MetS) have become increasingly significant global health issues. Time-restricted feeding (TRF), as a novel dietary intervention, has garnered attention in recent years. However, there is limited research focusing on the effects of TRF on energy expenditure and systemic low-grade inflammation. This study aims to investigate the impact of TRF on weight management, glucose metabolism, insulin resistance, and lipid metabolism in male C57BL/6J mice, particularly in the context of metabolic disorders induced by a high-fat diet (HFD).

Methods

C57BL/6J mice were divided into two groups: a normal diet (ND) group and a high-fat diet (HFD) group. The study duration was 12 weeks. Key parameters observed included body weight, glucose tolerance (via glucose tolerance tests), insulin resistance (HOMA-IR), and insulin secretion under glucose stimulation. Additionally, liver tissue was subjected to Oil Red O staining to assess lipid accumulation, and white and brown adipose tissues were stained with hematoxylin and eosin (HE) to evaluate adipocyte size. The expression of hepatic lipogenesis-related genes (Srebp-c, Chrebp, Fasn, and Acc1) and thermogenic genes in brown adipose tissue (UCP1 and PGC-1α) were also measured. Furthermore, temperature changes in the interscapular brown adipose tissue (BAT) were monitored.

Results

In the ND group: TRF improved insulin resistance and reduced circulating levels of the pro-inflammatory cytokine IL-6, with a slight reduction in body weight.In the HFD group: TRF significantly mitigated weight gain, improved glucose tolerance and insulin resistance, and enhanced insulin secretion under glucose stimulation. Additionally, TRF reduced hepatic steatosis by downregulating the expression of lipogenesis-related genes in the liver. TRF also increased thermogenesis by upregulating the expression of thermogenic genes (UCP1 and PGC-1α) in BAT, while lowering serum levels of pro-inflammatory cytokines IL-6 and TNF-α, though IL-1β levels remained unchanged.

Conclusion

This study demonstrates that TRF can activate thermogenesis in brown adipose tissue and reduce inflammation maker, leading to an improvement in hepatic steatosis and a reduction in white adipose tissue accumulation. These findings suggest that TRF may be a promising intervention for mitigating metabolic disturbances associated with obesity and metabolic syndrome. The study provides mechanistic insights into the beneficial effects of TRF, highlighting its potential in modulating lipid metabolism and exerting anti-inflammatory effects.

Cardiac Urea Cycle Activation by Time-Restricted Feeding Protects Against Pressure Overload-Induced Heart Failure

Heart failure is a leading cause of mortality worldwide, necessitating the development of novel therapeutic and lifestyle interventions. Recent studies highlight a potential role of time-restricted feeding (TRF) in the prevention and treatment of cardiac diseases. Here, it is found that TRF protected against heart failure at different stages in mice. Metabolomic profiling revealed that TRF upregulated most circulating amino acids, and amino acid supplementation protected against heart failure. In contrast, TRF showed a mild effect on cardiac amino acid profile, but increased cardiac amino acid utilization and activated the cardiac urea cycle through upregulating argininosuccinate lyase (ASL) expression. Cardiac-specific ASL knockout abolished the cardioprotective effects afforded by TRF. Circulating amino acids also protected against heart failure through activation of the urea cycle. Additionally, TRF upregulated cardiac ASL expression through transcription factor Yin Yang 1, and urea cycle-derived NO contributes to TRF-afforded cardioprotection. Furthermore, arteriovenous gradients of circulating metabolites across the human hearts were measured, and found that amino acid utilization and urea cycle activity were impaired in patients with decreased cardiac function. These results suggest that TRF is a promising intervention for heart failure, and highlight the importance of urea cycle in regulation of cardiac function.

Fasting alleviates bleomycin-induced lung inflammation and fibrosis via decreased Tregs and monocytes

PURPOSE

Idiopathic pulmonary fibrosis (IPF), a chronic and progressively worsening condition characterized by interstitial lung inflammation and fibrosis of unknown etiology, has a grim prognosis. The treatment options for IPF are limited and new therapeutic strategies are urgently needed. Dietary restriction can improve various inflammatory diseases, but its therapeutic effect on bleomycin (BLM)-induced pulmonary fibrosis mouse model remains unclear. This study aims to investigate whether intermittent fasting (IF) can alleviate BLM-induced pulmonary inflammation and fibrosis.

METHODS

Pulmonary fibrosis mouse models were induced by BLM. The IF group underwent 24-h fasting cycles for one week prior and three weeks following BLM administration. Meanwhile, the ad libitum feeding group had unrestricted access to food throughout the experiment. The evaluation focused on lung pathology via histological staining, qPCR analysis of collagen markers, and immune cell profiling through flow cytometry.

RESULTS

IF group significantly reduced inflammation and fibrosis in lung tissues of BLM-induced mice compared to ad libitum feeding group. qPCR results showed IF remarkably decreased the mRNA expression of Col 1a and Col 3a in the lungs of BLM-induced mouse models. IF also reduced the numbers of regulatory T cells (Tregs), T helper 17 (Th17) cells, monocytes, and monocyte-derived alveolar macrophages (MoAMs) in the lung tissues.

CONCLUSIONS

IF may improve BLM-induced pulmonary fibrosis by decreasing numbers of immune cells including Treg cells, Th17 ​cells, monocytes, and MoAMs in the lungs. This study offers experimental validation for dietary intervention as a viable treatment modality in IPF management.

From fasting to fat reshaping: exploring the molecular pathways of intermittent fasting-induced adipose tissue remodeling

Obesity, characterised by excessive fat accumulation, is a complex chronic condition that results from dysfunctional adipose tissue expansion due to prolonged calorie surplus. This leads to rapid adipocyte enlargement that exceeds the support capacity of the surrounding neurovascular network, resulting in increased hypoxia, inflammation, and insulin resistance. Intermittent fasting (IF), a dietary regimen that cycles between periods of fasting and eating, has emerged as an effective strategy to combat obesity and improve metabolic homeostasis by promoting healthy adipose tissue remodeling. However, the precise molecular and cellular mechanisms behind the metabolic improvements and remodeling of white adipose tissue (WAT) driven by IF remain elusive. This review aims to summarise and discuss the relationship between IF and adipose tissue remodeling and explore the potential mechanisms through which IF induces alterations in WAT. This includes several key structural changes, including angiogenesis and sympathetic innervation of WAT. We will also discuss the involvement of key signalling pathways, such as PI3K, SIRT, mTOR, and AMPK, which potentially play a crucial role in IF-mediated metabolic adaptations.

Associations of Dietary and Lifestyle Components with Atrial Fibrillation

Atrial fibrillation (AF) is a prevalent cardiac arrhythmia that still remains a significant health concern, especially due to its consequences, including stroke and heart failure. This review explores the intricate interplay between AF, lifestyle choices, and dietary habits. It is particularly focused on findings from diverse studies about non-pharmacological methods of managing AF. Moreover, its purpose is to elucidate the implementation of lifestyle changes such as physical activity or proper diet choices in the integrated treatment strategy of patients with AF.

Exerkine β-aminoisobutyric acid protects against atrial structural remodeling and atrial fibrillation in obesity via activating AMPK signaling and improving insulin sensitivity

Moderate exercise decreases the risk for atrial fibrillation (AF), an effect which is probably mediated via exercise-stimulated release of exerkines. β-Aminoisobutyric acid (BAIBA), a novel exerkine, has been reported to provide protective benefits against many cardiovascular diseases, yet its role in AF remains elusive. Herein, using a mouse model of obesity-related AF through high-fat diet (HFD) feeding, we found that 12-week drinking administration of BAIBA (170 mg/kg/day) decreased AF susceptibility in obese mice. Atrial remodeling assessment showed that BAIBA attenuated obesity-induced atrial hypertrophy and interstitial fibrosis, thereby ablating the substrate for AF. Of note, to our knowledge, this is the first report of the direct association of BAIBA and hypertrophy. BAIBA has been reported to be a key regulator of glucose and lipid metabolism, and we found that BAIBA alleviated insulin resistance in obese mice. Transcriptional analysis of metabolism-related genes showed that BAIBA increased the transcription of fatty acids metabolism-related genes in the atria of lean mice but not in that of obese mice. Mechanistic investigation showed that BAIBA stimulated AMP-activated protein kinase (AMPK) signaling in the atria of obese mice and palmitic acid (PA)-treated neonatal rat cardiomyocytes (NRCM), whereas inhibition of AMPK via Compound C attenuated BAIBA-conferred cardioprotection against hypertrophy and insulin resistance in PA-treated NRCM. Collectively, BAIBA attenuates AF susceptibility in obese mice via activated AMPK signaling and resultant improvement of insulin sensitivity, thereby providing perspectives on the potential therapeutic role of BAIBA in AF treatment.

SIRT3 regulates mitochondrial function: A promising star target for cardiovascular disease therapy

Dysregulation of mitochondrial homeostasis is common to all types of cardiovascular diseases. SIRT3 regulates apoptosis and autophagy, material and energy metabolism, mitochondrial oxidative stress, inflammation, and fibrosis. As an important mediator and node in the network of mechanisms, SIRT3 is essential to many activities. This review explains how SIRT3 regulates mitochondrial homeostasis and the tricarboxylic acid cycle to treat common cardiovascular diseases. A novel description of the impact of lifestyle factors on SIRT3 expression from the angles of nutrition, exercise, and temperature is provided.