Skeletal muscle-specific Bambi deletion induces hypertrophy and oxidative switching coupling with adipocyte thermogenesis against metabolic disorders

Skeletal muscle plays a significant role in both local and systemic energy metabolism. The current investigation aims to explore the role of the Bambi gene in skeletal muscle, focusing on its implications for muscle hypertrophy and systemic metabolism. We hypothesize that skeletal muscle-specific deletion of Bambi induces muscle hypertrophy, improves metabolic performance, and activates thermogenic adipocytes via the reprogramming of progenitor of iWAT, offering potential therapeutic strategies for metabolic syndromes. Leveraging the Chromatin immunoprecipitation (ChIP)-seq and bioinformatics analysis, Bambi gene is shown to be a direct target of HIF2α, which is further confirmed by ChIP-qPCR and promoter luciferase assay. Skeletal muscle-specific Bambi deletion led to significant muscle hypertrophy and improved metabolic parameters, even under high-fat diet conditions. This deletion induced metabolic reprogramming of stromal vascular fractions (SVFs) into thermogenic adipocytes, contributing to systemic metabolic improvements, potentially through the secretory factor. Notably, mice with skeletal muscle-specific Bambi deletion demonstrate resistance to high-fat diet-induced metabolic disorders, highlighting a potential therapeutic pathway for metabolic syndrome management. Thus, skeletal muscle-specific deletion of Bambi triggers muscle growth, enhances metabolic performance, and activates thermogenic adipocytes. These findings suggest Bambi as a novel therapeutic target for metabolic syndromes, providing new insights into the interaction between muscle hypertrophy and systemic metabolic improvement. The study underscores the potential of manipulating muscle physiology to regulate whole-body metabolism, offering a novel perspective on treating metabolic disorders.

The interconnective role of the UPS and autophagy in the quality control of cancer mitochondria

Uncontrollable cancer cell growth is characterized by the maintenance of cellular homeostasis through the continuous accumulation of misfolded proteins and damaged organelles. This review delineates the roles of two complementary and synergistic degradation systems, the ubiquitin-proteasome system (UPS) and the autophagy-lysosome system, in the degradation of misfolded proteins and damaged organelles for intracellular recycling. We emphasize the interconnected decision-making processes of degradation systems in maintaining cellular homeostasis, such as the biophysical state of substrates, receptor oligomerization potentials (e.g., p62), and compartmentalization capacities (e.g., membrane structures). Mitochondria, the cellular hubs for respiration and metabolism, are implicated in tumorigenesis. In the subsequent sections, we thoroughly examine the mechanisms of mitochondrial quality control (MQC) in preserving mitochondrial homeostasis in human cells. Notably, we explored the relationships between mitochondrial dynamics (fusion and fission) and various MQC processes-including the UPS, mitochondrial proteases, and mitophagy-in the context of mitochondrial repair and degradation pathways. Finally, we assessed the potential of targeting MQC (including UPS, mitochondrial molecular chaperones, mitochondrial proteases, mitochondrial dynamics, mitophagy and mitochondrial biogenesis) as cancer therapeutic strategies. Understanding the mechanisms underlying mitochondrial homeostasis may offer novel insights for future cancer therapies.

Daily Lipolysis Gene Expression in Male Rat Mesenteric Adipose Tissue: Obesity and Melatonin Effects

Melatonin is involved in various functions such as the timing of circadian rhythms, energy metabolism, and body mass gain in experimental animals. However, its effects on adipose tissue lipid metabolism are still unclear. This study analyzes the effects of melatonin on the relative gene expression of lipolytic proteins in rat mesenteric adipose tissue and free fatty acid (FFA) and glycerol plasma levels of male Wistar rats fed a high-fat (HFD) or maintenance diet. Four experimental groups were established: control, obese, and control or obese plus 2.3 mg/kg/day of melatonin in tap water. After 11 weeks, animals were sacrificed at different times throughout a 24 h cycle, and mesenteric adipose tissue and plasma samples were collected and analyzed. Cgi58, Perilipin, and Dgat1 gene expression, as well as FFA and glycerol concentrations, showed rhythm patterns in the control group. HFD disrupted those rhythm patterns and increased FFA and glycerol concentrations during the dark photoperiod. In both melatonin-treated groups, almost all analyzed genes showed circadian patterns. Notably, melatonin significantly prevented the increase in FFA levels during the dark photoperiod in obese rats (obese group: ~1100 mM vs. obese + melatonin group: ~600 μM, similar to control levels). However, the rhythmic pattern observed in control animals was not sustained. According to our results, melatonin could regulate circadian gene transcription of mesenteric adipose tissue lipolysis proteins. The effect of melatonin on preventing elevated FFA plasma levels associated with high-fat diet intake warrants further investigation.

Integrative analysis of angiogenic signaling in obesity: capillary features and VEGF binding kinetics

Obesity is a global health crisis, with its prevalence particularly severe in the United States, where over 42% of adults are classified as obese. Obesity is driven by complex molecular and tissue-level mechanisms that remain poorly understood. Among these, angiogenesis-primarily mediated by vascular endothelial growth factor (VEGF-A)-is critical for adipose tissue expansion but presents unique challenges for therapeutic targeting due to its intricate regulation. Systems biology approaches have advanced our understanding of VEGF-A signaling in vascular diseases, but their application to obesity is limited by scattered and sometimes contradictory data. To address this gap, we performed a comprehensive analysis of the existing literature to synthesize key findings, standardize data, and provide a holistic perspective on the adipose vascular microenvironment. The data mining revealed five key findings: (1) obesity increases adipocyte size by 78%; (2) vessel density in adipose tissue decreases by 51% in obese mice, with vessels being 47-58% smaller and 4-9 times denser in comparison with tumor vessels; (3) capillary basement membrane thickness remains similar regardless of obesity; (4) VEGF-A shows the strongest binding affinity for VEGFR1, with four times stronger affinity for VEGFR2 than for NRP1; and (5) binding affinities measured by radioligand binding assay and surface plasmon resonance (SPR) are significantly different. These consolidated findings provide essential parameters for systems biology modeling, new insights into obesity-induced changes in adipose tissue, and a foundation for developing angiogenesis-targeting therapies for obesity.

Bone Adaptations to a Whole Body Vibration Protocol in Murine Models of Different Ages: A Preliminary Study on Structural Changes and Biomarker Evaluation

Background/Objectives: Whole body vibration (WBV) is a valuable tool to mitigate physiological adaptations related to age and inactivity. Although significant benefits have been found at the musculoskeletal level, including increased bone mass and reduced muscle atrophy, the underlying biological mechanisms remain largely unknown. Therefore, our study aimed to evaluate the effects of vibratory training on bone tissue in murine models of different age groups by investigating the structural and distribution changes in some crucial biomarkers involved in musculoskeletal homeostasis. Methods: Specifically, 4-, 12-, and 24-month-old mice were trained with a WBV protocol characterized by three series of 2 min and 30 s, interspersed with a recovery period of the same duration, on a 3-weekly frequency for 3 months. At the end of the training, histological and morphometric analyses were conducted, in association with immunohistochemical analysis to investigate changes in the distribution of fibronectin type III domain-containing protein 5 (FNDC5), NADPH oxidase 4 (NOX4), and sirtuin 1 (SIRT1). Results: Our preliminary results showed that WBV improves musculoskeletal health by preserving bone architecture and promoting up-regulation of FNDC5 and SIRT1 and down-regulation of NOX4. Conclusions: Our study confirms vibratory training as a viable alternative to counter musculoskeletal decline in elderly and/or sedentary subjects. Further investigations should be conducted to deepen knowledge in this field and explore the role of other molecular mediators in physiological adaptations to vibration.

Omics Approaches to Study Perilipins and Their Significant Biological Role in Cardiometabolic Disorders

Lipid droplets (LDs), highly dynamic cellular organelles specialized in lipid storage and maintenance of lipid homeostasis, contain several proteins on their surface, among which the perilipin (Plin) family stands out as the most abundant group of LD-binding proteins. They play a pivotal role in influencing the behavior and functionality of LDs, regulating lipase activity, and preserving a balance between lipid synthesis and degradation, which is crucial in the development of obesity and abnormal accumulation of fat in non-adipose tissues, causing negative adverse biological effects, such as insulin resistance, mitochondrial dysfunction, and inflammation. The expression levels of Plins are often associated with various diseases, such as hepatic steatosis and atherosclerotic plaque formation. Thus, it becomes of interest to investigate the Plin roles by using appropriate "omics" approaches that may provide additional insight into the mechanisms through which these proteins contribute to cellular and tissue homeostasis. This review is intended to give an overview of the most significant omics studies focused on the characterization of Plin proteins and the identification of their potential targets involved in the development and progression of cardiovascular and cardiometabolic complications, as well as their interactors that could be useful for more efficient therapeutic and preventive approaches for patients.

Complement 3a receptor 1 on macrophages and Kupffer cells is not required for the pathogenesis of metabolic dysfunction-associated steatotic liver disease

Together with obesity and type 2 diabetes, metabolic dysfunction-associated steatotic liver disease (MASLD) is a growing global epidemic. Activation of the complement system and infiltration of macrophages has been linked to progression of metabolic liver disease. The role of complement receptors in macrophage activation and recruitment in MASLD remains poorly understood. In human and mouse, C3AR1 in the liver is expressed primarily in Kupffer cells, but is downregulated in humans with MASLD compared to obese controls. To test the role of complement 3a receptor (C3aR1) on macrophages and liver resident macrophages in MASLD, we generated mice deficient in C3aR1 on all macrophages (C3aR1-MφKO) or specifically in liver Kupffer cells (C3aR1-KpKO) and subjected them to a model of metabolic steatotic liver disease. We show that macrophages account for the vast majority of C3ar1 expression in the liver. Overall, C3aR1-MφKO and C3aR1-KpKO mice have similar body weight gain without significant alterations in glucose homeostasis, hepatic steatosis and fibrosis, compared to controls on a MASLD-inducing diet. This study demonstrates that C3aR1 deletion in macrophages or Kupffer cells, the predominant liver cell type expressing C3ar1, has no significant effect on liver steatosis, inflammation or fibrosis in a dietary MASLD model.

Understanding the Role of Irisin in Longevity and Aging: A Narrative Review

Irisin is a protein resulting from a proteolytic cleavage of fibronectin type III domain-containing protein 5 (FND5). The ability of irisin to modulate adipocyte and control glucose metabolism in human metabolic diseases gave rise to the hypothesis that irisin could have a pivotal role in aging-related diseases. Although in animal models, increased levels of irisin have been positively associated with better health outcomes, in humans, its role remains controversial. To provide an overview of the main finding on irisin in older adults, a comprehensive search was performed through the MEDLINE-PubMed, Web of Science, Scopus, and Cochrane databases for studies conducted in older adults (≥60 years) published since 2012. After grouping and analyzing the articles based on diseases associated with older adults, the main conclusion of this narrative review is that the included studies did not yield consistent evidence regarding the association between irisin and health or disease in older adults. Further studies are necessary to clarify the effective role of this protein in promoting health and longevity.

Effects of time-of-day on the noradrenaline, adrenaline, cortisol and blood lipidome response to an ice bath

While the effect of time-of-day (morning versus evening) on hormones, lipids and lipolysis has been studied in relation to meals and exercise, there are no studies that have investigated the effects of time-of-day on ice bath induced hormone and lipidome responses. In this crossover-designed study, a group of six women and six men, 26 ± 5 years old, 176 ± 7 cm tall, weighing 75 ± 10 kg, and a BMI of 23 ± 2 kg/m2 had an ice bath (8-12 °C for 5 min) both in the morning and evening on separate days. Absence from intense physical exercise, nutrient intake and meal order was standardized in the 24 h prior the ice baths to account for confounders such as diet or exercise. We collected venous blood samples before and after (5 min and 30 min) the ice baths to measure hormones (noradrenaline, adrenaline, and cortisol) and lipid levels in plasma via liquid chromatography mass spectrometry shotgun lipidomics. We found that ice baths in the morning increase plasma fatty acids more than in the evening. Overall plasma lipid composition significantly differed in-between the morning and evening, and only in the morning ice bathing is accompanied by significantly increased plasma fatty acids from 5.1 ± 2.2% to 6.0 ± 2.4% (P = 0.029) 5 min after and to 6.3 ± 3.1% (P = 0.008) 30 min after. Noradrenaline was not affected by time-of-day and increased significantly immediately after the ice baths in the morning by 127 ± 2% (pre: 395 ± 158 pg/ml, post 5 min: 896 ± 562 pg/ml, P = 0.025) and in the evening by 144 ± 2% (pre: 385 ± 146 pg/ml, post 5 min: 937 ± 547 pg/ml, P = 0.015). Cortisol was generally higher in the morning than in the evening (pre: 179 ± 108 pg/ml versus 91 ± 59 pg/ml, P = 0.013; post 5 min: 222 ± 96 pg/ml versus 101 ± 52 pg/ml, P = 0.001; post 30 min: 190 ± 96 pg/ml versus 98 ± 54 pg/ml, P = 0.009). There was no difference in the hormonal and lipidome response to an ice bath between women and men. The main finding of the study was that noradrenaline, adrenaline, cortisol and plasma lipidome responses are similar after an ice bath in the morning and evening. However, ice baths in the morning increase plasma fatty acids more than in the evening.

Study on gene expression in the liver at various developmental stages of human embryos

Background

The normal development of the liver during human embryonic stages is critical for the functionality of the adult liver. Despite this, the essential genes, biological processes, and signal pathways that drive liver development in human embryos remain poorly understood.

Methods

In this study, liver samples were collected from human embryos at progressive developmental stages, ranging from 2-month-old to 7-month-old. Highly expressed genes and their associated enrichment processes at various developmental stages of the liver were identified through transcriptomic sequencing.

Results

The findings indicated that genes associated with humoral immune responses and B-cell-mediated immunity were highly expressed during the early developmental stages. Concurrently, numerous genes related to vitamin response, brown adipocyte differentiation, T cell differentiation, hormone secretion, hemostasis, peptide hormone response, steroid metabolism, and hematopoietic regulation exhibited increased expression aligned with liver development. Our results suggest that the liver may possess multiple functions during embryonic stages, beyond serving hematopoietic roles. Moreover, this study elucidated the complex regulatory interactions among genes involved in lymphocyte differentiation, the regulation of hemopoiesis, and liver development. Consequently, the development of human embryonic liver necessitates the synergistic regulation of numerous genes. Notably, alongside conventionally recognized genes, numerous previously uncharacterized genes involved in liver development and function were also identified.

Conclusion

These findings establish a critical foundation for future research on liver development and diseases arising from fetal liver abnormalities.

The GIP receptor activates futile calcium cycling in white adipose tissue to increase energy expenditure and drive weight loss in mice

Obesity is a chronic disease that contributes to the development of insulin resistance, type 2 diabetes (T2D), and cardiovascular risk. Glucose-dependent insulinotropic polypeptide (GIP) receptor (GIPR) and glucagon-like peptide-1 (GLP-1) receptor (GLP-1R) co-agonism provide an improved therapeutic profile in individuals with T2D and obesity when compared with selective GLP-1R agonism. Although the metabolic benefits of GLP-1R agonism are established, whether GIPR activation impacts weight loss through peripheral mechanisms is yet to be fully defined. Here, we generated a mouse model of GIPR induction exclusively in the adipocyte. We show that GIPR induction in the fat cell protects mice from diet-induced obesity and triggers profound weight loss (∼35%) in an obese setting. Adipose GIPR further increases lipid oxidation, thermogenesis, and energy expenditure. Mechanistically, we demonstrate that GIPR induction activates SERCA-mediated futile calcium cycling in the adipocyte. GIPR activation further triggers a metabolic memory effect, which maintains weight loss after the transgene has been switched off, highlighting a unique aspect in adipocyte biology. Collectively, we present a mechanism of peripheral GIPR action in adipose tissue, which exerts beneficial metabolic effects on body weight and energy balance.

Repeated fasting events sensitize enhancers, transcription factor activity and gene expression to support augmented ketogenesis

Mammals withstand frequent and prolonged fasting periods due to hepatic production of glucose and ketone bodies. Because the fasting response is transcriptionally regulated, we asked whether enhancer dynamics impose a transcriptional program during recurrent fasting and whether this generates effects distinct from a single fasting bout. We found that mice undergoing alternate-day fasting (ADF) respond profoundly differently to a following fasting bout compared to mice first experiencing fasting. Hundreds of genes enabling ketogenesis are 'sensitized' (i.e. induced more strongly by fasting following ADF). Liver enhancers regulating these genes are also sensitized and harbor increased binding of PPARα, the main ketogenic transcription factor. ADF leads to augmented ketogenesis compared to a single fasting bout in wild-type, but not hepatocyte-specific PPARα-deficient mice. Thus, we found that past fasting events are 'remembered' in hepatocytes, sensitizing their enhancers to the next fasting bout and augment ketogenesis. Our findings shed light on transcriptional regulation mediating adaptation to repeated signals.

The mitochondria as a potential therapeutic target in cerebral I/R injury

Ischemic stroke is a major cause of mortality and disability worldwide. Among patients with ischemic stroke, the primary treatment goal is to reduce acute cerebral ischemic injury and limit the infarct size in a timely manner by ensuring effective cerebral reperfusion through the administration of either intravenous thrombolysis or endovascular therapy. However, reperfusion can induce neuronal death, known as cerebral reperfusion injury, for which effective therapies are lacking. Accumulating data supports a paradigm whereby cerebral ischemia/reperfusion (I/R) injury is coupled with impaired mitochondrial function, contributing to the pathogenesis of ischemic stroke. Herein, we review recent evidence demonstrating a heterogeneous mitochondrial response following cerebral I/R injury, placing a specific focus on mitochondrial protein modifications, reactive oxygen species, calcium (Ca2+), inflammation, and quality control under experimental conditions using animal models.

Glutamine metabolism is systemically different between primary and induced pluripotent stem cell-derived brain microvascular endothelial cells

Human primary (hpBMEC) and induced pluripotent stem cell (iPSC)-derived brain microvascular endothelial-like cells (hiBMEC) are interchangeably used in blood-brain barrier models to study neurological diseases and drug delivery. Both hpBMEC and hiBMEC use glutamine as a source of carbon and nitrogen to produce metabolites and build proteins essential to cell function and communication. We used metabolomic, transcriptomic, and computational methods to examine how hpBMEC and hiBMEC metabolize glutamine, which may impact their utility in modeling the blood-brain barrier. We found that glutamine metabolism was systemically different between the two cell types. hpBMEC had a higher metabolic rate and produced more glutamate and GABA, while hiBMEC rerouted glutamine to produce more glutathione, fatty acids, and asparagine. Higher glutathione production in hiBMEC correlated with higher oxidative stress compared to hpBMEC. α-ketoglutarate (α-KG) supplementation increased glutamate secretion from hiBMEC to match that of hpBMEC; however, α-KG also decreased hiBMEC glycolytic rate. These fundamental metabolic differences between BMEC types may impact in vitro blood-brain barrier model function, particularly communication between BMEC and surrounding cells, and emphasize the importance of evaluating the metabolic impacts of iPSC-derived cells in disease models.

Irisin reshapes bone metabolic homeostasis to delay age-related osteoporosis by regulating the multipotent differentiation of BMSCs via Wnt pathway

Introduction

Bone aging is linked to changes in the lineage differentiation of bone marrow stem cells (BMSCs), which show a heightened tendency to differentiate into adipocytes instead of osteoblasts. The therapeutic potential of irisin in addressing age-related diseases has garnered significant attention. More significantly, irisin has the capacity to enhance bone mass recovery and sustain overall bone health. Its mechanism of action in preventing osteoporosis has generated considerable interest within the research community. Nonetheless, the targeting effect of irisin on age-related osteoporosis and its underlying molecular biological mechanisms remain unclear.

Methods

The specific role of irisin in osteogenic-adipogenic differentiation in young or aging BMSCs was evaluated by multiple cells staining and quantitative real-time PCR (RT-qPCR) analysis. RNA-seq and protein Western blotting excavated and validated the key pathway by which irisin influences the fate determination of aging BMSCs. The macroscopic and microscopic changes of bone tissue in aging mice were examined using Micro-computed tomography (Micro-CT) and morphological staining.

Results

It was noted that irisin affected the multilineage differentiation of BMSCs in a manner dependent on the dosage. Simultaneously, the Wnt signaling pathway might be a crucial mechanism through which irisin sustains the bone-fat balance in aging BMSCs and mitigates the decline in pluripotency. In vivo, irisin reduced bone marrow fat deposition in aging mice and effectively alleviating the occurrence of bone loss.

Conclusion

Irisin mediates the Wnt signaling pathway, thereby influencing the fate determination of BMSCs. In addition, it is essential for preserving metabolic equilibrium in the bone marrow microenvironment and significantly contributes to overall bone health. The findings provide new evidence for the use of iris extract in the treatment of age-related osteoporosis.

Emerging debates and resolutions in brown adipose tissue research

Until two decades ago, brown adipose tissue (BAT) was studied primarily as a thermogenic organ of small rodents in the context of cold adaptation. The discovery of functional human BAT has opened new opportunities to understand its physiological role in energy balance and therapeutic applications for metabolic disorders. Significantly, the role of BAT extends far beyond thermogenesis, including glucose and lipid homeostasis, by releasing mediators that communicate with other cells and organs. The field has made major advances by using new model systems, ranging from subcellular studies to clinical trials, which have also led to debates. In this perspective, we identify six fundamental issues that are currently controversial and comprise dichotomous models. Each side presents supporting evidence and, critically, the necessary methods and falsifiable experiments that would resolve the dispute. With this collaborative approach, the field will continue to productively advance the understanding of BAT physiology, appreciate the importance of thermogenic adipocytes as a central area of ongoing research, and realize the therapeutic potential.

Epidemiological features of uterine fibroid-associated imaging changes in Chinese women of reproductive age: a retrospective study

OBJECTIVES

To investigate uterine fibroid (UF)-associated imaging changes, and their prevalence, incidence and potential risk factors in the Chinese population.

DESIGN

This was a retrospective observational study using health examination data.

SETTING

A physical examination centre in Nanchong, China, between October 2017 and December 2020.

PARTICIPANTS

A total of 33 915 Chinese women older than 15 years of age underwent uterine imaging during the study period.

PRIMARY AND SECONDARY OUTCOME MEASURES

This study identified entries of UF-associated imaging changes through a two-round expert consultation and calculated prevalence and incidence of UF-associated imaging changes. Logistic regression estimated the association (OR, 95% CI of body mass index, high blood pressure (HBP), blood lipid profile, and fasting blood glucose level) with UF-associated imaging changes. Age-stratified (≤40 years and >40 years) risks were ascertained.

RESULTS

Besides the entry 'Potential UF', 17 other entries of UF-associated imaging changes screened by the expert consultation were included, involving a total of 46 864 records (n=33 915), and crude prevalence=25.18%; crude incidence density/1000-woman-years=63.28. Incidence and prevalence increased with age during reproductive age (15-49 years) and decreased thereafter. The greatest burden was in women aged 40-54 years, the prevalence was 38.60%-45.38% and the incidence was 14.73%-17.96%. In the incident younger population (age ≤40 years), overweight (OR: 1.48, 95% CI 1.03 to 2.14) and HBP (OR: 2.16, 95% CI 1.10 to 4.24) were associated with a higher risk for UF-associated imaging changes; in the >40 years group, no association was observed.

CONCLUSION

UF incidence and prevalence in Asians were higher than previously reported, showed age-related increase in reproductive age, and UF incidence increased with overweight and HBP in ≤40-year-old participants. Variation in UF burden and factors with higher risk noted in different age ranges, and the correlations identified in younger women make it possible for early preventive measures for women with a higher risk of UF.

Mitochondria-giant lipid droplet proximity and autophagy suppression in nitrogen-depleted oleaginous yeast Lipomyces starkeyi cells

Balancing energy production and storage is a fundamental process critical for cellular homeostasis in most eukaryotes that relies on the intimate interplay between mitochondria and lipid droplets (LDs). In the oleaginous yeast Lipomyces starkeyi under nitrogen starvation, LD forms a single giant spherical structure that is easily visible under a light microscope. Currently, how mitochondria behave in L. starkeyi cells undergoing giant LD formation remains unknown. Here we show that mitochondria transition from fragments to elongated tubules and sheet-like structures that are in close proximity to a giant LD in nitrogen-depleted L. starkeyi cells. Under the same conditions, mitochondrial degradation and autophagy are strongly suppressed, suggesting that these catabolic events are not required for giant LD formation. Conversely, carbon-depleted cells suppress mitochondrial elongation and LD expansion, whereas they promote mitochondrial degradation and autophagy. We propose a potential link of mitochondrial proximity and autophagic suppression to giant LD formation.

Skeletal Site-Specific Lipid Profile and Hematopoietic Progenitors of Bone Marrow Adipose Tissue in Patients Undergoing Primary Hip Arthroplasty

BACKGROUND/OBJECTIVES

Bone marrow adipose tissue (BMAT) has been described as an important biomechanic and lipotoxic factor with negative impacts on skeletal and hematopoietic system regeneration. BMAT undergoes metabolic and cellular adaptations with age and disease, being a source of potential biomarkers. However, there is no evidence on the lipid profile and cellularity at different skeletal locations in osteoarthritis patients undergoing primary hip arthroplasty.

METHODS

Acetabular and femoral bone marrow (BM) and gluteofemoral subcutaneous adipose tissue (gfSAT) were obtained from matched patients undergoing hip replacement surgery. BM, BMAT, and gfSAT were explored at the levels of total lipids, fatty acids, and cells by using thin-layerand gas chromatography, ex vivo cellular assays, and flow cytometry.

RESULTS

BMAT content was significantly higher in femoral than in acetabular BM. Total lipid analyses revealed significantly lower triglyceride content in femoral than in acetabular BMAT and gfSAT. Frequencies of saturated palmitic, myristic, and stearic acids were higher in femoral than in acetabular BMAT and gfSAT. The content of CD45+CD34+ cells within femoral BMAT was higher than in acetabular BMAT or gfSAT. This was associated with a higher incidence of total clonogenic hematopoietic progenitors and late erythroid colonies CFU-E in femoral BMAT when compared to acetabular BMAT, similar to their BM counterparts.

CONCLUSIONS

Collectively, our results indicate that the lipid profiles of hip bone and femoral BMAT impose significantly different microenvironments and distributions of cells with hematopoietic potential. These findings might bring forth new inputs for defining BMAT biology and setting novel directions in OA disease investigations.

Exercise-driven cellular autophagy: A bridge to systematic wellness

BACKGROUND

Exercise enhances health by supporting homeostasis, bolstering defenses, and aiding disease recovery. It activates autophagy, a conserved cellular process essential for maintaining balance, while dysregulated autophagy contributes to disease progression. Despite extensive research on exercise and autophagy independently, their interplay remains insufficiently understood.

AIM OF REVIEW

This review explores the molecular mechanisms of exercise-induced autophagy in various tissues, focusing on key transduction pathways. It examines how different types of exercise trigger specific autophagic responses, supporting cellular balance and addressing systemic dysfunctions. The review also highlights the signaling pathways involved, their roles in protecting organ function, reducing disease risk, and promoting longevity, offering a clear understanding of the link between exercise and autophagy.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Exercise-induced autophagy is governed by highly coordinated and dynamic pathways integrating direct and indirect mechanical forces and biochemical signals, linking physical activity to cellular and systemic health across multiple organ systems. Its activation is influenced by exercise modality, intensity, duration, and individual biological characteristics, including age, sex, and muscle fiber composition. Aerobic exercises primarily engage AMPK and mTOR pathways, supporting mitochondrial quality and cellular homeostasis. Anaerobic training activates PI3K/Akt signaling, modulating molecules like FOXO3a and Beclin1 to drive muscle autophagy and repair. In pathological contexts, exercise-induced autophagy enhances mitochondrial function, proteostasis, and tissue regeneration, benefiting conditions like sarcopenia, neurodegeneration, myocardial ischemia, metabolic disorders, and cancer. However, excessive exercise may lead to autophagic overactivation, leading to muscle atrophy or pathological cardiac remodeling. This underscores the critical need for balanced exercise regimens to maximize therapeutic efficacy while minimizing risks. Future research should prioritize identifying reliable biomarkers, optimizing exercise protocols, and integrating exercise with pharmacological strategies to enhance therapeutic outcomes.

Serum Irisin Levels Are Positively Correlated with Physical Activity Capacity in Hemodialysis Patients

INTRODUCTION

Regular physical activity is beneficial for health but is often reduced in patients receiving maintenance hemodialysis treatment. Irisin is a muscle-secreted hormone that reportedly improves metabolism and slows down the progression of some chronic diseases. In this study, we aimed to investigate the relationship between physical activity capacity and serum irisin levels in hemodialysis patients.

METHODS

Our study included 252 patients undergoing hemodialysis at Xuanwu Hospital Capital Medical University. Enzyme-linked immunosorbent assay was used to measure blood irisin levels. Body composition was analyzed by bioelectrical impedance analysis. The International Physical Activity Questionnaire (IPAQ) was used to score physical activity ability.

RESULTS

Bivariate correlation analysis showed a positive correlation between IPAQ scores and ln irisin (the natural logarithm of irisin; r = 0.326, p < 0.001). Independent determinants of IPAQ scores were ln irisin, age, fasting glucose, and carbon dioxide combining power.

CONCLUSION

Our findings provide the first clinical evidence that serum irisin levels are positively correlated with physical activity capacity in hemodialysis patients.

Phenotyping atherosclerotic plaque and perivascular adipose tissue: signalling pathways and clinical biomarkers in atherosclerosis

Computed tomography coronary angiography provides a non-invasive evaluation of coronary artery disease that includes phenotyping of atherosclerotic plaques and the surrounding perivascular adipose tissue (PVAT). Image analysis techniques have been developed to quantify atherosclerotic plaque burden and morphology as well as the associated PVAT attenuation, and emerging radiomic approaches can add further contextual information. PVAT attenuation might provide a novel measure of vascular health that could be indicative of the pathogenetic processes implicated in atherosclerosis such as inflammation, fibrosis or increased vascularity. Bidirectional signalling between the coronary artery and adjacent PVAT has been hypothesized to contribute to coronary artery disease progression and provide a potential novel measure of the risk of future cardiovascular events. However, despite the development of more advanced radiomic and artificial intelligence-based algorithms, studies involving large datasets suggest that the measurement of PVAT attenuation contributes only modest additional predictive discrimination to standard cardiovascular risk scores. In this Review, we explore the pathobiology of coronary atherosclerotic plaques and PVAT, describe their phenotyping with computed tomography coronary angiography, and discuss potential future applications in clinical risk prediction and patient management.

Murine gut microbial interactions exert antihyperglycemic effects

The correlations between gut microbiota and host metabolism have been studied extensively, whereas little relevant work has been done to investigate the impact of gut microbial interactions on host metabolism. With the use of a bacteriocin-targeting strategy, we aimed to identify the gut microbes associated with glucose and lipid metabolism by adjusting the gut microbial composition of mice fed a high-fat diet. To fulfill this goal, a Listeria monocytogenes (Lmo)-derived bacteriocin Lmo2776 secretion module was constructed and integrated into the genome of Escherichia coli Nissle 1917 (EcN), yielding the Lmo2776-secreting strain EcN-2776. In high-fat diet-fed mice, EcN-2776 administration decreased blood glucose and increased serum triglyceride, and gene amplicon sequencing of 16S rRNA in these mice indicated that intestinal secretion of Lmo2776 led to adjustment of the gut microbial composition. Specifically, Lmo2776 restricted the growth of Ligilactobacillus murinus, thus alleviating its inhibitory impact towards Faecalibaculum rodentium. Further analyses indicated that F. rodentium administration decreased the fasting blood glucose of high-fat diet-fed mice, an effect that may be attributable to the intestinal consumption of glucose by F. rodentium. In this study, we identified the gut microbes associated with glucose metabolism, uncovered their interactions, and deciphered the impact of these gut microbial interactions on the host glucose metabolism. Our findings may pave the way for the treatment of hyperglycemia from the perspective of gut microbial interactions.

Paracrine role of endothelial IGF-1 receptor in depot-specific adipose tissue adaptation in male mice

During recent decades, changes in lifestyle have led to widespread nutritional obesity and its related complications. Remodelling adipose tissue as a therapeutic goal for obesity and its complications has attracted much attention and continues to be actively explored. The endothelium lines all blood vessels and is close to all cells, including adipocytes. The endothelium has been suggested to act as a paracrine organ. We explore the role of endothelial insulin-like growth factor-1 receptor (IGF-1R), as a paracrine modulator of white adipose phenotype. We show that a reduction in endothelial IGF-1R expression in the presence of high-fat feeding in male mice leads to depot-specific beneficial white adipose tissue remodelling, increases whole-body energy expenditure and enhances insulin sensitivity via a non-cell-autonomous paracrine mechanism. We demonstrate that increased endothelial malonate may be contributory and that malonate prodrugs have potentially therapeutically relevant properties in the treatment of obesity-related metabolic disease.

The transcriptional repressor HEY2 regulates mitochondrial oxidative respiration to maintain cardiac homeostasis

Energy deprivation and metabolic rewiring of cardiomyocytes are widely recognized hallmarks of heart failure. Here, we report that HEY2 (a Hairy/Enhancer-of-split-related transcriptional repressor) is upregulated in hearts of patients with dilated cardiomyopathy. Induced Hey2 expression in zebrafish hearts or mammalian cardiomyocytes impairs mitochondrial respiration, accompanied by elevated ROS, resulting in cardiomyocyte apoptosis and heart failure. Conversely, Hey2 depletion in adult mouse hearts and zebrafish enhances the expression of mitochondrial oxidation genes and cardiac function. Multifaceted genome-wide analyses reveal that HEY2 enriches at the promoters of genes known to regulate metabolism (including Ppargc1, Esrra and Cpt1) and colocalizes with HDAC1 to effectuate histone deacetylation and transcriptional repression. Consequently, restoration of PPARGC1A/ESRRA in Hey2- overexpressing zebrafish hearts or human cardiomyocyte-like cells rescues deficits in mitochondrial bioenergetics. Knockdown of Hey2 in adult mouse hearts protects against doxorubicin-induced cardiac dysfunction. These studies reveal an evolutionarily conserved HEY2/HDAC1-Ppargc1/Cpt transcriptional module that controls energy metabolism to preserve cardiac function.

Deep learning and genome-wide association meta-analyses of bone marrow adiposity in the UK Biobank

Bone marrow adipose tissue is a distinct adipose subtype comprising more than 10% of fat mass in healthy humans. However, the functions and pathophysiological correlates of this tissue are unclear, and its genetic determinants remain unknown. Here, we use deep learning to measure bone marrow adiposity in the femoral head, total hip, femoral diaphysis, and spine from MRI scans of approximately 47,000 UK Biobank participants, including over 41,000 white and over 6300 non-white participants. We then establish the heritability and genome-wide significant associations for bone marrow adiposity at each site. Our meta-GWAS in the white population finds 67, 147, 134, and 174 independent significant single nucleotide polymorphisms, which map to 54, 90, 43, and 100 genes for the femoral head, total hip, femoral diaphysis, and spine, respectively. Transcriptome-wide association studies, colocalization analyses, and sex-stratified meta-GWASes in the white participants further resolve functional and sex-specific genes associated with bone marrow adiposity at each site. Finally, we perform a multi-ancestry meta-GWAS to identify genes associated with bone marrow adiposity across the different bone regions and across ancestry groups. Our findings provide insights into BMAT formation and function and provide a basis to study the impact of BMAT on human health and disease.

Relationship of serum irisin levels, physical activity, and metabolic syndrome biomarkers in obese individuals with low-calorie intake and non-obese individuals with high-calorie intake

BACKGROUND

Despite all the advances in our knowledge regarding obesity, our understanding of its etiology is still far from complete. This study aimed to evaluate the association of serum irisin levels with physical activity and some of the metabolic syndrome-related biomarkers among obese people with low-calorie intake and non-obese people with high-calorie intake.

METHODS

Obese and non-obese healthy individuals with respectively low and high-calorie intakes were recruited. Irisin and other biomarkers were measured using standard biochemical methods. Participants' physical activity was evaluated by administering the International Physical Activity Questionnaire (IPAQ). To analyze the body composition of the participants, a standard body composition device (ioi 353) was applied. Logistic regression was used to calculate the odds ratio (OR) and to examine the effect of confounders such as age, sex, genetics, and activity.

RESULTS

Data from the seventy-seven participants were included in the final analysis. The mean age of the participants in the obese and non-obese groups was 38.33 ± 14.88 and 30.24 ± 13.37 years, respectively. Participants in the obese group had lower physical activity compared to the non-obese group (3395.38 ± 2801 MET-min/week vs. 6015.18 ± 3178 MET-min/week; p < 0.001). The Irisin concentration in the obese and non-obese groups was 7.84 ± 2.49 ng/ml and 8.06 ± 1.89 ng/ml, respectively, which wasn't significantly different (p = 0.66). We observed a noteworthy and favorable association between irisin concentration and total body water (TBW), lean body mass (LBM), and soft lean mass (SLM) in the non-obese group.

CONCLUSIONS

These data indicated that although obese participants were relatively inactive compared to non-obese individuals, circulating irisin level wasn't significantly different between the two groups.

Diacylglycerol kinase alpha regulates post-hepatectomy liver regeneration

Diacylglycerol kinases (DGKs) phosphorylate diacylglycerol to generate phosphatidic acid, which plays important roles in intracellular signal transduction. DGKα is reportedly associated with progression of tumors, including hepatocellular carcinomas, but its relationship with liver regeneration has not been examined. The purpose of this research is to elucidate the role of DGKα in liver regeneration. Here, we provide a detailed examination of C57BL/6 wild-type and DGKα knockout (KO) mice subjected to 70% partial hepatectomy (70% PH) modeling, including survival rates, hematological marker and gene expression levels, and histological analyses of factors related to liver regeneration. Following 70% PH, DGKα KO mice produce higher levels of hepatobiliary enzymes and have a higher incidence of jaundice compared with wild-type mice, with a death rate of ~ 40%. Furthermore, they exhibit impaired glycogen and lipid consumption, low liver energy charge, and hepatocyte hypertrophy disorder, accompanied by significantly reduced liver expression of proliferating cell nuclear antigen and cyclin D. We conclude that DGKα is a key molecule in the post-PH liver regeneration process and may have potential as a therapeutic target for the acceleration of liver regeneration.

Parathyroidectomy Reduces Inflammatory Cytokines and Increases Vitamin D Metabolites in Patients With Primary Hyperparathyroidism

OBJECTIVE

Primary hyperparathyroidism (PHPT) is accompanied by a decreased 25-hydroxyvitamin D (25OHD) and vitamin D binding protein (DBP). High parathyroid hormone (PTH) is associated with elevated interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1), yet the effect of parathyroidectomy (PTX) on DBP and cytokines is not clear. This study aims to prospectively evaluate the effect of PTX on inflammatory profiles, total and free 25OHD, and DBP in patients with PHPT.

METHODS

Newly diagnosed patients with PHPT were recruited for the study (n = 70). Twenty-eight patients returned after PTX, 3 months later. Biochemical markers were measured before and after PTX. A group of age and body mass index-matched healthy subjects were included as controls (n = 70).

RESULTS

Before PTX, patients had lower serum DBP (37.5 ± 6.0 vs 41.5 ± 6.1 mg/dL, P < .001) and total 25OHD (30.1 ± 9.5 vs 33.3 ± 7.9 ng/mL, P < .05) but similar free 25OHD when compared to controls. Serum IL-6, C-reactive protein, and MCP-1 were higher in patients with PHPT (P < .05), whereas interleukin-10 was similar to that in controls. PTX increased total and free 25OHD and DBP (P < .001) and decreased serum IL-6 and MCP-1 (P < .05), but not C-reactive protein and interleukin-10. Multiple regression analysis indicated that the preoperative PTH explained a significant portion of the variance of IL-6 and MCP-1 (P < .05).

CONCLUSION

These findings suggest that PTH may upregulate the production of MCP-1 and IL-6 and downregulate circulating DBP in patients with PHPT that are normalized by PTX. The exact mechanism of IL-6 and MCP-1 on DBP, vitamin D metabolites, and clinical outcomes in patients with PHPT is an area requiring further study.

Mitochondrial metabolism: A moving target in hepatocellular carcinoma therapy

Mitochondria are pivotal contributors to cancer mechanisms due to their homeostatic and pathological roles in cellular bioenergetics, biosynthesis, metabolism, signaling, and survival. During transformation and tumor initiation, mitochondrial function is often disrupted by oncogenic mutations, leading to a metabolic profile distinct from precursor cells. In this review, we focus on hepatocellular carcinoma, a cancer arising from metabolically robust and nutrient rich hepatocytes, and discuss the mechanistic impact of altered metabolism in this setting. We provide distinctions between normal mitochondrial activity versus disease-related function which yielded therapeutic opportunities, along with highlighting recent preclinical and clinical efforts focused on targeting mitochondrial metabolism. Finally, several novel strategies for exploiting mitochondrial programs to eliminate hepatocellular carcinoma cells in metabolism-specific contexts are presented to integrate these concepts and gain foresight into the future of mitochondria-focused therapeutics.

The Multifaceted Role of the Polyphenol Curcumin: A Focus on Type 2 Diabetes Mellitus

Type 2 Diabetes Mellitus (T2DM) is a chronic metabolic disorder characterized by chronic hyperglycemia, which often co-exists with other metabolic impairments. This condition can damage various tissues and organs, resulting in the development of severe complications, both microvascular, such as retinopathy, nephropathy, and neuropathy, and macrovascular, responsible for an increased risk of cardiovascular diseases. Curcumin is the main bioactive molecule found in the rhizomes of turmeric. Many studies have reported curcumin to exhibit antioxidant, anti-inflammatory, anti-infectious, and anti-cancer properties; thus, there is an increasing interest in exploiting these properties in order to prevent the rise or the progression of T2DM, as well as its possible associated conditions. In this review, we have presented the current state-ofart regarding the clinical trials that have involved curcumin administration and analyzed the possible mechanisms by which curcumin might exert the beneficial effects observed in literature.

Organellar quality control crosstalk in aging-related disease: Innovation to pave the way

Organellar homeostasis and crosstalks within a cell have emerged as essential regulatory and determining factors for the survival and functions of cells. In response to various stimuli, cells can activate the organellar quality control systems (QCS) to maintain homeostasis. Numerous studies have demonstrated that dysfunction of QCS can lead to various aging-related diseases such as neurodegenerative, pulmonary, cardiometabolic diseases and cancers. However, the interplay between QCS and their potential role in these diseases are poorly understood. In this review, we present an overview of the current findings of QCS and their crosstalk, encompassing mitochondria, endoplasmic reticulum, Golgi apparatus, ribosomes, peroxisomes, lipid droplets, and lysosomes as well as the aberrant interplays among these organelles that contributes to the onset and progression of aging-related disorders. Furthermore, potential therapeutic approaches based on these quality control interactions are discussed. Our perspectives can enhance insights into the regulatory networks underlying QCS and the pathology of aging and aging-related diseases, which may pave the way for the development of novel therapeutic targets.

Exploring the reduction in aquaporin-4 and increased expression of ciliary neurotrophic factor with the frontal-striatal gliosis induced by chronic high-fat dietary stress

High-fat diet (HFD)-induced obesity induces peripheral inflammation and hypothalamic pathogenesis linking the activation of astrocytes and microglia. Clinical evidence indicates a positive correlation between obesity and psychiatric disorders, such as depression. The connectivity of the frontal-striatal (FS) circuit, involving the caudate putamen (CPu) and anterior cingulate cortex (ACC) within the prefrontal cortex (PFC), is known for its role in stress-induced depression. Thus, there is a need for a thorough investigation into whether chronic obesity-induced gliosis, characterized by the activation of astrocytes and microglia, in these brain regions of individuals with chronic obesity. The results revealed increased S100β+ astrocytes and Iba1+ microglia in the CPu and ACC of male obese mice, along with immune cell accumulation in meningeal lymphatic drainage. Activated GFAP+ astrocytes and Iba1+ microglia were observed in the corpus callosum of obese mice. Gliosis in the CPu and ACC was linked to elevated cleaved caspase-3 levels, indicating potential neural cell death by chronic HFD feeding. There was a loss of myelin and adenomatous polyposis coli (APC)+ oligodendrocytes (OLs) in the corpus callosum, an area known to be linked with injury to the CPu. Additionally, reduced levels of aquaporin-4 (AQP4), a protein associated within the glymphatic systems, were noted in the CPu and ACC, while ciliary neurotrophic factor (CNTF) gene expression was upregulated in these brain regions of obese mice. The in vitro study revealed that high-dose CNTF causing a trend of reduced astrocytic AQP4 expression, but it significantly impaired OL maturation. This pathological evidence highlights that prolonged HFD consumption induces persistent FS gliosis and demyelination in the corpus callosum. An elevated level of CNTF appears to act as a potential regulator, leading to AQP4 downregulation in the FS areas and demyelination in the corpus callosum. This cascade of events might contribute to neural cell damage within these regions and disrupt the glymphatic flow.

Blockage of ATGL-mediated breakdown of lipid droplets in microglia alleviates neuroinflammatory and behavioural responses to lipopolysaccharides

Lipid droplets (LD) are triglyceride storing organelles that have emerged as an important component of cellular inflammatory responses. LD lipolysis via adipose triglyceride lipase (ATGL), the enzyme that catalyses the rate-limiting step of triglyceride lipolysis, regulates inflammation in peripheral immune and non-immune cells. ATGL elicits both pro- and anti-inflammatory responses in the periphery in a cell-type dependent manner. The present study determined the impact of ATGL inhibition and microglia-specific ATGL genetic loss-of-function on acute inflammatory and behavioural responses to pro-inflammatory insult. First, we evaluated the impact of lipolysis inhibition on lipopolysaccharide (LPS)-induced expression and secretion of cytokines and phagocytosis in mouse primary microglia cultures. Lipase inhibitors (ORlistat and ATGListatin) and LPS led to LD accumulation in microglia. Pan-lipase inhibition with ORlistat alleviated LPS-induced expression of IL-1β and IL-6. Specific inhibition of ATGL had a similar action on CCL2, IL-1β and IL-6 expression in both neonatal and adult microglia cultures. CCL2 and IL-6 secretion were also reduced by ATGListatin or knockdown of ATGL. ATGListatin increased phagocytosis in neonatal cultures independently from LPS treatment. Second, targeted and untargeted lipid profiling revealed that ATGListatin reduced LPS-induced generation of pro-inflammatory prostanoids and modulated ceramide species in neonatal microglia. Finally, the role of microglial ATGL in neuroinflammation was assessed using a novel microglia-specific and inducible ATGL knockout mouse model. Loss of microglial ATGL in adult male mice dampened LPS-induced expression of IL-6 and IL-1β and microglial density. LPS-induced sickness- and anxiety-like behaviours were also reduced in male mice with loss of ATGL in microglia. Together, our results demonstrate potent anti-inflammatory effects produced by pharmacological or genetic inhibition of ATGL-mediated triglyceride lipolysis and thereby propose that supressing microglial LD lipolysis has beneficial actions in acute neuroinflammatory conditions.

PGC-1α regulation by FBXW7 through a novel mechanism linking chaperone-mediated autophagy and the ubiquitin-proteasome system

Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) is a key regulator of mitochondrial biogenesis and antioxidative defenses, and it may play a critical role in Parkinson's disease (PD). F-box/WD repeat domain-containing protein (FBXW7), an E3 protein ligase, promotes the degradation of substrate proteins through the ubiquitin-proteasome system (UPS) and leads to the clearance of PGC-1α. Here, we elucidate a novel post-translational mechanism for regulating PGC-1α levels in neurons. We show that enhancing chaperone-mediated autophagy (CMA) activity promotes the CMA-mediated degradation of FBXW7 and consequently increases PGC-1α. We confirm the relevance of this pathway in vivo by showing decreased FBXW7 and increased PGC-1α as a result of boosting CMA selectively in dopaminergic (DA) neurons by overexpressing lysosomal-associated membrane protein 2A (LAMP2A) in TH-Cre-LAMP2-loxp conditional mice. We further demonstrate that these mice are protected against MPTP-induced oxidative stress and neurodegeneration. These results highlight a novel regulatory pathway for PGC-1α in DA neurons and suggest targeted increasing of CMA or decreasing FBXW7 in DA neurons as potential neuroprotective strategies in PD.

Origin of dedifferentiated adipocyte-derived cells (DFAT) during ceiling culture in an Adiponectin Cre-Recombinase mouse model

DFAT cells represent an attractive source of stem cells in tissue engineering and in the potential treatment of several clinical conditions. Our objective was to determine whether DFAT cells originate from mature adipocytes and address whether contamination from the stromal vascular fraction (SVF) could be as a source for these cells. A murine adiponectin-creERT;mT/mG model was used with the excision of the cassette induced by tamoxifen injection for the cells expressing adiponectin (adipoq). This model allows distinguishing of mature adipocytes (green fluorescence) from other SVF cell types (red fluorescence) based on the fluorescent protein expressed. Mature adipocytes and SVF cells were isolated from adipose tissues by collagenase digestion. Ceiling cultures were imaged by time-lapse microscopy. Confocal microscopy was used to follow cells over 21 days. Time-lapse microscopy experiments showed liposecretion occurring in mature adipocytes displaying green fluorescence. Confocal imaging allowed the identification of a heterogeneous cell population expressing green but also red fluorescence after 21 days of culture. Asymmetrical division of mature adipocytes was not observed. In conclusion, liposecretion of mature adipocytes is a phenomenon that can be observed in vitro and DFAT cells do originate from mature adipocytes. However, the population of DFAT cells is heterogenous.

The protective effect of irisin against hemorrhagic injury is mediated by PI3K and p38 pathways in hemorrhage/resuscitation

The objective of this study was to investigate whether phosphoinositide 3-kinase (PI3K) and p38 mitogen-activated kinase contribute to the protection of irisin during hemorrhage/resuscitation. Experimental groups were divided based on the different treatments during resuscitation as follows: (1) hemorrhage: adult male CD-1 mice were subjected to hemorrhage at a mean arterial blood pressure of 35-45 mm Hg for 60 minutes, followed by resuscitation with shed blood and lactated Ringer's solution (n = 13); (2) hemorrhage + irisin: receiving irisin (5 μg/kg; n = 13); (3) hemorrhage + irisin + PI3K inhibitor: receiving both Ly294002 (1 mg/kg, i.v.) and irisin (n = 6); and (4) hemorrhage + irisin + p38 inhibitor: receiving SB202190 (1 mg/kg, i.v.) and irisin (n = 6). Compared with hemorrhage/resuscitation control, irisin improved cardiac function and the recovery of hemodynamics in association with the decreased systemic interleukin (IL)-1, IL-6, and tumor necrosis factor (TNF)-α, which were completely abrogated by PI3K or p38 inhibitions. Furthermore, the inhibition of PI3K or p38 abolished irisin-induced reduction of the inflammatory cell infiltration and terminal deoxynucleotidyl transferase-mediated digoxigenin-deoxyuridine nick-end labeling-positive apoptosis in the cardiac and skeletal muscles. Irisin reduced TNF-α and IL-6 expression in cardiac and skeletal muscles, which was abrogated by the inhibition of PI3K or p38. Irisin-treated hemorrhage increases the phosphorylation of PI3K and p38 in both cardiac and skeletal muscles, which was mitigated by the inhibition of PI3K or p38. PI3K and p38 play an important role in modulating the protective effect of irisin during the hemorrhage/resuscitation. SIGNIFICANCE STATEMENT: This study has identified a critical pathway in the regulation of trauma/hemorrhage by using a preclinical trauma model, in which irisin, as a hormone factor, stimulates PI3K and p38 pathways to induce protection against traumatic conditions. The study holds promise for developing a new therapeutic strategy to target irisin and its pathways related to PI3K and p38 to treat trauma and its comorbidities to reduce mortality for clinical implications.

Single-cell omics: experimental workflow, data analyses and applications

Cells are the fundamental units of biological systems and exhibit unique development trajectories and molecular features. Our exploration of how the genomes orchestrate the formation and maintenance of each cell, and control the cellular phenotypes of various organismsis, is both captivating and intricate. Since the inception of the first single-cell RNA technology, technologies related to single-cell sequencing have experienced rapid advancements in recent years. These technologies have expanded horizontally to include single-cell genome, epigenome, proteome, and metabolome, while vertically, they have progressed to integrate multiple omics data and incorporate additional information such as spatial scRNA-seq and CRISPR screening. Single-cell omics represent a groundbreaking advancement in the biomedical field, offering profound insights into the understanding of complex diseases, including cancers. Here, we comprehensively summarize recent advances in single-cell omics technologies, with a specific focus on the methodology section. This overview aims to guide researchers in selecting appropriate methods for single-cell sequencing and related data analysis.

Key Players in the Complex Pathophysiology of Obesity: A Cross-Talk Between the Obesogenic Genes and Unraveling the Metabolic Pathway of Action of Capsaicin and Orange Peel

Obesity is a widespread prevailing health concern with multifactorial causes. Among the various defined molecular targets associated with obesity, peroxisome proliferator activated receptor gamma, leptin, ghrelin, and adiponectin play crucial roles in fundamental processes including energy balance, adipose tissue biology, and metabolic health, making them particularly significant in the study of obesity.Capsaicin and orange peel exhibit promising anti-obesity properties through their thermogenic, metabolic, and anti-inflammatory effects. Potential pathways for therapeutic approaches in the management of obesity are provided by these targets. The lipid-lowering and anti-obesity benefits of specific plant species have been highlighted in Asian medicine. Due to the potential anti-obesity qualities, capsaicin, which is derived from chilli peppers, and orange peel extract has been focused in this review. Capsaicin causes apoptosis in preadipocytes and adipocytes and suppresses adipogenesis. Citrus fruits are a significant source of bioactive substances, primarily flavonoids. Due to their ability to reduce adipocyte development and cellular lipid content, citrus polyphenols are helpful in the control of obesity. This extensive analysis offers insights into new treatment approaches for the prevention and management of obesity and metabolic syndrome by examining the interactions of molecular variables in obesity as well as the possible anti-obesity advantages of capsaicin and orange peel extract.

VEGFB promotes adipose tissue thermogenesis by inhibiting norepinephrine clearance in macrophages

Adipokines play key roles in adaptive thermogenesis of beige adipocytes, though its detailed regulatory mechanisms are not fully understood. In the present study, we identify a critical function of vascular endothelial growth factor B (VEGFB)/vascular endothelial growth factor receptor 1 (VEGFR1) signaling in improving thermogenesis in white adipose tissue (WAT). In mouse subcutaneous WAT (scWAT), thermogenesis activation leads to the up-regulation of VEGFB in adipocytes and its receptor VEGFR1 in macrophages. Ablation of adipocyte VEGFB results in deficiency in murine WAT browning. Meanwhile, supplementation of VEGFB promotes WAT thermogenesis, but this effect is blocked by knockout of macrophage VEGFR1. Mechanistic studies show that the VEGFB-activated VEGFR1 inhibits p38 MAPK signaling through its dissociation with receptor for activated C kinase 1, thereby preventing norepinephrine transporter (solute carrier family 6 member 2) and norepinephrine-degrative monoamine oxidase a mediated norepinephrine clearance in macrophages. Our findings demonstrate that VEGFB/VEGFR1 circuit contributes to the WAT thermogenesis.

Sarcopenia and cachexia: molecular mechanisms and therapeutic interventions

Sarcopenia is defined as a muscle-wasting syndrome that occurs with accelerated aging, while cachexia is a severe wasting syndrome associated with conditions such as cancer and immunodeficiency disorders, which cannot be fully addressed through conventional nutritional supplementation. Sarcopenia can be considered a component of cachexia, with the bidirectional interplay between adipose tissue and skeletal muscle potentially serving as a molecular mechanism for both conditions. However, the underlying mechanisms differ. Recognizing the interplay and distinctions between these disorders is essential for advancing both basic and translational research in this area, enhancing diagnostic accuracy and ultimately achieving effective therapeutic solutions for affected patients. This review discusses the muscle microenvironment's changes contributing to these conditions, recent therapeutic approaches like lifestyle modifications, small molecules, and nutritional interventions, and emerging strategies such as gene editing, stem cell therapy, and gut microbiome modulation. We also address the challenges and opportunities of multimodal interventions, aiming to provide insights into the pathogenesis and molecular mechanisms of sarcopenia and cachexia, ultimately aiding in innovative strategy development and improved treatments.

Resveratrol stimulates brown of white adipose via regulating ERK/DRP1-mediated mitochondrial fission and improves systemic glucose homeostasis

PURPOSE

Diabetes mellitus and metabolic homeostasis disorders may benefit from white adipose tissue (WAT) browning, which is associated with mitochondrial fission. Resveratrol, a dietary polyphenol, exhibits beneficial effects against abnormalities related to metabolic diseases. However, it remains unknown whether resveratrol contributes to WAT browning by regulating mitochondrial fission.

METHODS

We administered resveratrol (0.4% mixed with control) to db/db mice for 12 weeks, measuring body weight, oral glucose tolerance, insulin tolerance, and histological changes. The uncoupling protein 1 (UCP1) and dynamin-related protein 1 (DRP1) expressions in the epididymal WAT were assessed via immunoblotting.

RESULTS

We found that resveratrol improved systemic glucose homeostasis and insulin resistance in db/db mice, which was associated with increased UCP1 in epididymal WAT. Resveratrol-treated mice exhibited more fragmented mitochondria and increased phosphorylation of DRP1 in the epididymal WAT of the db/db mice. These results were further confirmed in vitro, where resveratrol induced extracellular signal-regulated kinase (ERK) signaling activation, leading to phosphorylation of DRP1 at the S616 site (p-DRP1S616) and mitochondrial fission, which was reversed by an ERK inhibitor in 3T3-L1 adipocytes.

CONCLUSION

Resveratrol plays a role in regulating the phosphorylation of ERK and DRP1, resulting in the promotion of beige cells with epididymal WAT and the improvement of glucose homeostasis. Our present study provides novel insights into the potential mechanism of resveratrol-mediated effects on WAT browning, suggesting that it is, at least in part, mediated through ERK/DRP1-mediated mitochondrial fission.

Inflammation and resolution in obesity

Inflammation is an essential physiological defence mechanism, but prolonged or excessive inflammation can cause disease. Indeed, unresolved systemic and adipose tissue inflammation drives obesity-related cardiovascular disease and type 2 diabetes mellitus. Drugs targeting pro-inflammatory cytokine pathways or inflammasome activation have been approved for clinical use for the past two decades. However, potentially serious adverse effects, such as drug-induced weight gain and increased susceptibility to infections, prevented their wider clinical implementation. Furthermore, these drugs do not modulate the resolution phase of inflammation. This phase is an active process orchestrated by specialized pro-resolving mediators, such as lipoxins, and other endogenous resolution mechanisms. Pro-resolving mediators mitigate inflammation and development of obesity-related disease, for instance, alleviating insulin resistance and atherosclerosis in experimental disease models, so mechanisms to modulate their activity are, therefore, of great therapeutic interest. Here, we review current clinical attempts to either target pro-inflammatory mediators (IL-1β, NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome, tumour necrosis factor (TNF) and IL-6) or utilize endogenous resolution pathways to reduce obesity-related inflammation and improve cardiometabolic outcomes. A remaining challenge in the field is to establish more precise biomarkers that can differentiate between acute and chronic inflammation and to assess the functionality of individual leukocyte populations. Such advancements would improve the monitoring of drug effects and support personalized treatment strategies that battle obesity-related inflammation and cardiometabolic disease.

Anatomy, Histology, and Embryonic Origin of Adipose Tissue: Insights to Understand Adipose Tissue Homofunctionality in Regeneration and Therapies

Preadipocytes are formed during the 14th and 16th weeks of gestation. White adipose tissue, in particular, is generated in specific areas and thereby assembles after birth, rapidly increasing following the propagation of adipoblasts, which are considered the preadipocyte cell precursors. The second trimester of gestation is a fundamental phase of adipogenesis, and in the third trimester, adipocytes, albeit small may be present within the main deposition areas. In the course of late gestation, adipose tissue develops in the foetus and promotes the synthesis of large amounts of uncoupling protein 1, in similar quantities relative to differentiated brown adipose tissue. In mammals, differentiation occurs in two functionally different types of adipose cells: white adipose cells resulting from lipid storage and brown adipose cells from increased metabolic energy consumption. During skeletogenesis, synovial joints develop through the condensation of mesenchymal cells, which forms an insertional layer of flattened cells that umlaut skeletal elements, by sharing the same origin in the development of synovium. Peri-articular fat pads possess structural similarity with body subcutaneous white adipose tissue; however, they exhibit a distinct metabolic function due to the micro-environmental cues in which they are embedded. Fat pads are an important component of the synovial joint and play a key role in the maintenance of joint homeostasis. They are also implicated in pathological states such as osteoarthritis.In this paper we explore the therapeutic potential of adipocyte tissue mesenchymal precursor-based stem cell therapy linking it back to the anatomic origin of adipose tissue.

Heat acclimation defense against exertional heat stroke by improving the function of preoptic TRPV1 neurons

Rationale: Record-breaking heatwaves caused by greenhouse effects lead to multiple hyperthermia disorders, the most serious of which is exertional heat stroke (EHS) with the mortality reaching 60 %. Repeat exercise with heat exposure, termed heat acclimation (HA), protects against EHS by fine-tuning feedback control of body temperature (Tb), the mechanism of which is opaque. This study aimed to explore the molecular and neural circuit mechanisms of the HA training against EHS. Methods: Male C57BL/6 mice (6-8 weeks) and male TRPV1-Cre mice (6-8 weeks) were used in our experiments. The EHS model with or without HA training were established for this study. RNA sequencing, qPCR, immunoblot, immunofluorescent assays, calcium imaging, optogenetic/ chemical genetic intervention, virus tracing, patch clamp, and other methods were employed to investigate the molecular mechanism and neural circuit by which HA training improves the function of the medial preoptic area (mPOA) neurons. Furthermore, a novel exosome-based strategy targeting the central nervous system to deliver irisin, a protective peptide generated by HA, was established to protect against EHS. Results: HA-related neurons in the mPOA expressing transient receptor potential vanilloid-1 (TRPV1) were identified as a population whose activation reduces Tb; inversely, dysfunction of these neurons contributes to hyperthermia and EHS. mPOATRPV1 neurons facilitate vasodilation and reduce adipose tissue thermogenesis, which is associated with their inhibitory projection to the raphe pallidus nucleus (RPa) and dorsal medial hypothalamus (DMH) neurons, respectively. Furthermore, HA improves the function of preoptic heat-sensitive neurons by enhancing TRPV1 expression, and Trpv1 ablation reverses the HA-induced heat tolerance. A central nervous system-targeted exosome strategy to deliver irisin, a protective peptide generated by HA, can promote preoptic TRPV1 expression and exert similar protective effects against EHS. Conclusions: Preoptic TRPV1 neurons could be enhanced by HA, actively contributing to heat defense through the mPOA"DMH/RPa circuit during EHS, which results in the suppression of adipose tissue thermogenesis and facilitation of vasodilatation. A delivery strategy of exosomes engineered with RVG-Lamp2b-Irisin significantly improves the function of mPOATRPV1 neurons, providing a promising preventive strategy for EHS in the future.

Muscle PGC-1α Overexpression Drives Metabolite Secretion Boosting Subcutaneous Adipocyte Browning

Muscle and adipose tissue (AT) are in mutual interaction through the integration of endocrine and biochemical signals, thus regulating whole-body function and physiology. Besides a traditional view of endocrine relationships that imply the release of cytokines and growth factors, it is becoming increasingly clear that a metabolic network involving metabolites as signal molecules also exists between the two tissues. By elevating the number and functionality of mitochondria, a key role in muscle metabolism is played by the master regulator of mitochondrial biogenesis peroxisome-proliferator-activated receptor-γ coactivator-1α (PGC-1α), that induces a fiber type shift from glycolytic to oxidative myofibers. As a consequence, the upregulation of muscle respiratory rate might affect metabolite production and consumption. However, the underlying mechanisms have not yet been fully elucidated. Here, we used a muscle-specific PGC-1α overexpressing mouse model (MCK-PGC-1α) to analyze the metabolite secretion profile of serum and culture medium recovered from MCK-PGC-1α muscle fibers by NMR. We revealed modified levels of different metabolites that might be ascribed to the metabolic activation of the skeletal muscle fibers. Notably, the dysregulated levels of these metabolites affected adipocyte differentiation, as well as the browning process in vitro and in vivo. Interestingly such effect was exacerbated in the subcutaneous WAT, while only barely present in the visceral WAT. Our data confirm a prominent role of PGC-1α as a trigger of mitochondrial function in skeletal muscle and propose a novel function of this master regulator gene in modulating the metabolite production in turn affecting the activation of WAT and its conversion toward the browning.

The role of irisin and cytokines in the etiology of parotid tumors

This study explores the role of irisin and interleukins in parotid tumors by determining the tissue staining intensity of irisin, the salivary and plasma levels of irisin, and the plasma levels of IL-4, IL-6, IL-10 and TNF-alpha in individuals with parotid tumors. Forty-eight patients and forty healthy individuals were included to the study and allocated into four group. Benign Group I (pleomorphic adenoma), Group II (Warthin's tumor), Group III (mucoepidermoid carcinoma) and Group IV (benign parotid control group, healthy control group). Parotid tissue, plasma and saliva samples were collected from each of the patients with parotid tumors, while plasma and saliva samples were collected from the healthy individuals. Normal parotid tissue for histologic evaluation was obtained from unaffected areas in patients with parotid tumors. The levels of irisin in the plasma and saliva were significantly lower in the parotid tumors, while the plasma levels of IL-6 and TNF-alpha were higher in patients with parotid tumors, but no statistically significant difference in IL-4 and IL-10 levels was found. The histopathological intensity of FNDC-5/irisin staining was significantly decreased in the parotid tumor tissues when compared to the benign parotid control group with normal parotid tissue. The low histopathological tissue staining intensity and plasma and salivary levels of irisin suggest that irisin may be a protective protein in parotid tumors.