Myokines May Be the Answer to the Beneficial Immunomodulation of Tailored Exercise-A Narrative Review

Exercise can regulate the immune function, activate the activity of immune cells, and promote the health of the organism, but the mechanism is not clear. Skeletal muscle is a secretory organ that secretes bioactive substances known as myokines. Exercise promotes skeletal muscle contraction and the expression of myokines including irisin, IL-6, BDNF, etc. Here, we review nine myokines that are regulated by exercise. These myokines have been shown to be associated with immune responses and to regulate the proliferation, differentiation, and maturation of immune cells and enhance their function, thereby serving to improve the health of the organism. The aim of this article is to review the effects of myokines on intrinsic and adaptive immunity and the important role that exercise plays in them. It provides a theoretical basis for exercise to promote health and provides a potential mechanism for the correlation between muscle factor expression and immunity, as well as the involvement of exercise in body immunity. It also provides the possibility to find a suitable exercise training program for immune system diseases.

Correlation between insulin-like growth factor and complexity of glucose time series index in patients with newly diagnosed acromegaly: a PILOT study

BACKGROUND

Acromegaly has a high risk of abnormal glucose metabolism. The complexity of the glucose time series index (CGI) is calculated from refined composite multi-scale entropy analysis of the continuous glucose monitoring (CGM) data. CGI is a new indicator of glucose imbalance based on ambulatory glucose monitoring technology, which allows for earlier response to glucose metabolism imbalance and correlates with patient prognosis.

OBJECTIVE

To compare the differences in glucose metabolic profile and CGI between acromegaly with normal glucose tolerance (NGT) and healthy subjects.

METHODS

Eight newly diagnosed patients with acromegaly (GH group) and eight age- and gender-matched healthy subjects (Control group) were included in this study. All participants underwent oral glucose tolerance test (OGTT) and 72-h CGM. A refined composite multi-scale entropy analysis was performed on the CGM data to calculate the CGI and we compare the differences in glycemic profiles and CGI between the two groups.

RESULTS

After OGTT, compared with the control group, patients in the GH group had higher 2 h blood glucose (BG) (mmol/L) [GH vs control, 6.7 (6.1, 7.0) vs 5.2 (3.8, 6.3), P  = 0.012], 3 h BG [5.1 (3.8, 6.5) vs 4.0 (3.4, 4.2), P = 0.046], mean BG [6.3 (6.1, 6.5) vs 5.5 (5.1, 5.9), P = 0.002], 2 h insulin (mU/L) [112.9 (46.8, 175.5) vs 34.1 (17.1, 55.6), P = 0.009], and 3 h insulin [26.8 (17.1, 55.4) vs 10.4 (4.2, 17.8), P = 0.016]. CGI was lower in the GH group [2.77 (1.92, 3.15) vs 4.2 (3.3, 4.8), P = 0.008]. Spearman's correlation analysis showed insulin-like growth factor (IGF) (r = -0.897, P < 0.001) and mean glucose (r = -0.717, P = 0.003) were significantly negatively correlated with CGI. Multiple linear stepwise regression showed that IGF-1 (r = -0.652, P = 0.028) was independent factor associated with CGI in acromegaly.

CONCLUSION

IGF-1 was significantly associated with CGI, and CGI may serve as a novel marker to evaluate glucose homeostasis in acromegaly with normal glucose tolerance.

Unraveling of Molecular Mechanisms of Cognitive Frailty in Chronic Kidney Disease: How Exercise Makes a Difference

As our population ages, the medical challenges it faces become increasingly acute, with chronic kidney disease (CKD) becoming more prevalent among older adults. Frailty is alarmingly more common in CKD patients than in the general populace, putting the elderly at high risk of both physical and cognitive decline. CKD not only accelerates physical deterioration, but also heightens vascular dysfunction, calcification, arterial rigidity, systemic inflammation, oxidative stress, and cognitive impairment. Cognitive frailty, a distinct syndrome marked by cognitive deficits caused by physiological causes (excluding Alzheimer's and other dementias), is a critical concern. Although cognitive impairment has been well-studied, the molecular mechanisms driving cognitive frailty remain largely uncharted. Comprehensive interventions, including cutting-edge pharmaceuticals and lifestyle changes, are pivotal and effective, especially in the early stages of CKD. Recent research suggests that systematic exercise could counteract cognitive decline by improving brain blood flow, boosting neuroplasticity through the brain-derived neurotrophic factor (BDNF), and by triggering the release of neurotrophic factors such as insulin-like growth factor (IGF-1). This review delves into the molecular pathways of cognitive frailty in CKD, identifies key risk factors, and highlights therapeutic approaches, particularly the potent role of exercise in enhancing cognitive health.

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.

The modulatory effect of oat on brain-derived neurotrophic factor, orexigenic neuropeptides, and dopaminergic signaling in obesity-induced rat model: a comparative study to orlistat

BACKGROUND

Obesity is a non-communicable complex disease that is the fifth leading cause of death worldwide. According to a novel viewpoint, the brain plays a significant role in the central regulation of satiety and energy homeostasis. Because of its rich nutritional profile and versatile uses, oat (Avena sativa) is one of the most popular functional foods recommended by many nutritionists. The anti-obesity effect of oat was hypothesized, focusing on the brain as the target organ. In the current study, the interplay between brain biomarkers, obesity, and its related complications was evaluated in diet-induced obese rats for 25 weeks, in which 60 adult male white albino Wistar rats were divided into three control and seven treatment groups given oat extracts in a dose-dependent manner.

RESULTS

Oat significantly improved obesity-related metabolic complications. In terms of brain function, oat significantly increased dopaminergic signaling, brain-derived neurotrophic factor levels, vaspin, irisin, and uncoupling protein-1 brain levels, while decreasing the expression of agouti-related peptide and neuropeptide Y (P-value < 0.05).

CONCLUSION

The current study proposes oat supplementation as a new conceptual framework with numerous implications for hedonic and homeostatic mechanisms that control satiety. © 2024 Society of Chemical Industry.

Imaging and proteomics toolkits for studying organelle contact sites

Organelle contact sites are regions where two heterologous membranes are juxtaposed by molecular tethering complexes. These contact sites are important in inter-organelle communication and cellular functional integration. However, visualizing these minute foci and identifying contact site proteomes have been challenging. In recent years, fluorescence-based methods have been developed to visualize the dynamic physical interaction of organelles while proximity labeling approaches facilitate the profiling of proteomes at contact sites. In this review, we explain the design principle for these contact site reporters: a dual-organelle interaction mechanism based on how endogenous tethers and/or tethering complexes localize to contact sites. We classify the contact site reporters into three categories: (i) single-protein systems, (ii) two-component systems with activated reporter signal upon organelle proximity, and (iii) reporters for contact site proteomes. We also highlight advanced imaging analysis with high temporal-spatial resolution and the use of machine-learning algorithms for detecting contact sites.

Exerkines: Benign adaptation for exercise and benefits for non-alcoholic fatty liver disease

Exercise has multiple beneficial effects on human metabolic health and is regarded as a "polypill" for various diseases. At present, the lack of physical activity usually causes an epidemic of chronic metabolic syndromes, including obesity, cardiovascular diseases, and non-alcoholic fatty liver disease (NAFLD). Remarkably, NAFLD is emerging as a serious public health issue and is associated with the development of cirrhosis and hepatocellular carcinoma. Unfortunately, specific drug therapies for NAFLD and its more severe form, non-alcoholic steatohepatitis (NASH), are currently unavailable. Lifestyle modification is the foundation of treatment recommendations for NAFLD and NASH, especially for exercise. There are under-appreciated organs that crosstalk to the liver during exercise such as muscle-liver crosstalk. Previous studies have reported that certain exerkines, such as FGF21, GDF15, irisin, and adiponectin, are beneficial for liver metabolism and have the potential to be targeted for NAFLD treatment. In addition, some of exerkines can be modified for the new proteins and get enhanced functions, like IL-6/IC7Fc. Another importance of exercise is the physiological adaptation that combats metabolic diseases. Thus, this review aims to summarize the known exerkines and utilize a multi-omics mining tool to identify more exerkines for the future research. Overall, understanding the mechanisms by which exercise-induced exerkines exert their beneficial effects on metabolic health holds promise for the development of novel therapeutic strategies for NAFLD and related diseases.

Current knowledge and scientific trends in myokines and exercise research in the context of obesity

The relationship between exercise and obesity has attracted increasing attention from researchers worldwide in recent years. The aim of the present study was to analyze the current knowledge and scientific trends of research into myokines and exercise in the context of obesity and provide ideas for future research strategies to prevent obesity. The study conducted a comprehensive bibliometric analysis of 300 scientific publications related to myokines, exercise, and obesity from 2004 to 2024. Applying the VOSviewer tool, the analysis revealed a significant increase over time in the number of publications on these topics, with a total of 1,142 related keywords identified. Key themes identified in the analysis included molecular processes, new organokines, skeletal muscle research, model organism studies, and human studies based on sex and age differences. The study highlighted the growing interest in the molecular mechanisms of obesity and role of myokines. Results showed a substantial increase in publications from 2014 to 2024, with a focus on new organokines (myokines, adipokines) and animal models. The analysis underscored the importance of myokines in modulating metabolic processes and their potential therapeutic implications in managing non-communicable diseases such as obesity. Furthermore, the study revealed the close relationship between exercise, myokine production, and regulation of metabolism, stress response, and inflammation. In conclusion, over the last years, increasing research interest has been focused on the molecular mechanisms of obesity and benefits of exercise, and probably will be focused on a set of myokines released during muscle contraction. A newly identified myokines has emerged as a promising marker for the prevention and control of obesity.

Distinct Genomic Expression Signatures after Low-Force Electrically Induced Exercises in Persons with Spinal Cord Injury

People with a spinal cord injury are at an increased risk of metabolic dysfunction due to skeletal muscle atrophy and the transition of paralyzed muscle to a glycolytic, insulin-resistant phenotype. Providing doses of exercise through electrical muscle stimulation may provide a therapeutic intervention to help restore metabolic function for people with a spinal cord injury, but high-frequency and high-force electrically induced muscle contractions increase fracture risk for the underlying osteoporotic skeletal system. Therefore, we investigated the acute molecular responses after a session of either a 3 Hz or 1 Hz electrically induced exercise program. Ten people with a complete spinal cord injury completed a 1 h (3 Hz) or 3 h (1 Hz) unilateral electrically induced exercise session prior to a skeletal muscle biopsy of the vastus lateralis. The number of pulses was held constant. Tissue samples were analyzed for genomic and epigenomic expression profiles. There was a strong acute response after the 3 Hz exercise leading to the upregulation of early response genes (NR4A3, PGC-1α, ABRA, IRS2, EGR1, ANKRD1, and MYC), which have prominent roles in regulating molecular pathways that control mitochondrial biogenesis, contractile protein synthesis, and metabolism. Additionally, these genes, and others, contributed to the enrichment of pathways associated with signal transduction, cellular response to stimuli, gene expression, and metabolism. While there were similar trends observed after the 1 Hz exercise, the magnitude of gene expression changes did not reach our significance thresholds, despite a constant number of stimuli delivered. There were also no robust acute changes in muscle methylation after either form of exercise. Taken together, this study supports that a dose of low-force electrically induced exercise for 1 h using a 3 Hz stimulation frequency is suitable to trigger an acute genomic response in people with chronic paralysis, consistent with an expression signature thought to improve the metabolic and contractile phenotype of paralyzed muscle, if performed on a regular basis.

Brain-body mitochondrial distribution patterns lack coherence and point to tissue-specific and individualized regulatory mechanisms

Energy transformation capacity is generally assumed to be a coherent individual trait driven by genetic and environmental factors. This predicts that some individuals should have high and others low mitochondrial oxidative phosphorylation (OxPhos) capacity across organ systems. Here, we test this assumption using multi-tissue molecular and enzymatic activities in mice and humans. Across up to 22 mouse tissues, neither mitochondrial OxPhos capacity nor mtDNA density were correlated between tissues (median r = -0.01-0.16), indicating that animals with high mitochondrial capacity in one tissue can have low capacity in other tissues. Similarly, the multi-tissue correlation structure of RNAseq-based indices of mitochondrial gene expression across 45 tissues from 948 women and men (GTEx) showed small to moderate coherence between only some tissues (regions of the same brain), but not between brain-body tissue pairs in the same person (median r = 0.01). Mitochondrial DNA copy number (mtDNAcn) also lacked coherence across organs and tissues. Mechanistically, tissue-specific differences in mitochondrial gene expression were attributable in part to i) tissue-specific activation of canonical energy sensing pathways including the transcriptional coactivator PGC-1 and the integrated stress response (ISR), and ii) proliferative activity across tissues. Finally, we identify subgroups of individuals with high mitochondrial gene expression in some tissues (e.g., heart) but low expression in others (e.g., skeletal muscle) who display different clinical phenotypic patterns. Taken together, these data raise the possibility that tissue-specific energy sensing pathways may contribute to the idiosyncratic mitochondrial distribution patterns associated with the inter-organ heterogeneity and phenotypic diversity among individuals.

An immunology model for accelerated coronary atherosclerosis and unexplained sudden death in the COVID-19 era

The immunological basis for cardiac deaths remote from potential triggering viral infection, including SARS-CoV-2 infection, remains enigmatic. Cardiac surface inflammation, including the pericardium, epicardium and superficial myocardium with associated coronary artery vasculitis in infant Kawasaki Disease (KD) and multisystem inflammatory syndrome in children (MIS-C) is well recognised. In this perspective, we review the evidence pointing towards prominent post-viral infection related epicardial inflammation in older subjects, resulting in atherosclerotic plaque destabilisation with seemingly unrelated myocardial infarction that may be temporally distant from the actual infectious triggers. Cardiac surface inflammation in the relatively immune cell rich tissues in the territory though where the coronary arteries traverse is common in the adult post-COVD pneumonic phase and is also well described after vaccination including pre-COVID era vaccinations. Immunologically, the pericardium/epicardium tissue was known to be critical for coronary artery territory atherosclerotic disease prior to the COVID-19 era and may be linked to the involvement of the coronary artery vasa vasorum that physiologically oxygenates the coronary artery walls. We highlight how viral infection or vaccination-associated diffuse epicardial tissue inflammation adjacent to the coronary artery vasa vasorum territory represents a critical unifying concept for seemingly unrelated fatal coronary artery atherosclerotic disease, that could occur soon after or remote from infection or vaccination in adults. Mechanistically, such epicardial inflammation impacting coronary artery vasa vasorum immunity acts as gateways towards the slow destabilisation of pre-existing atherosclerotic plaques, with resultant myocardial infarction and other cardiac pathology. This model offers immunologists and academic cardiologists an immunopathological roadmap between innocuous viral infections or vaccinations and seemingly temporally remote "unrelated" atherosclerotic disease with excess cardiac deaths.

How Can Promoting Skeletal Muscle Health and Exercise in Children and Adolescents Prevent Insulin Resistance and Type 2 Diabetes?

Skeletal muscle secretome, through its paracrine and endocrine functions, contributes to the maintenance and regulation of overall physiological health. We conducted a narrative review on the role of skeletal muscle and exercise in maintaining glucose homeostasis, driving insulin resistance (IR), and preventing type 2 diabetes in pediatric populations, especially in the context of overweight and obesity. Myokines such as interleukin (IL)-6, IL-8, and IL-15, as well as irisin, myonectin, and myostatin, appear to play a crucial role in IR. Skeletal muscle can also become a target of obesity-induced and IR-induced inflammation. In the correlation between muscle, IR, and inflammation, the role of infiltration of the immune cells and the microvasculature may also be considered. It remains unclear which exercise approach is the best; however, combining aerobic exercise with resistance training seems to be the most effective strategy for managing IR, with high-intensity activities offering superior metabolic benefits and long-term adherence. Encouraging daily participation in enjoyable and engaging exercise is key for long-term commitment and effective glucose metabolism management. Promoting physical activity in children and adolescents must be a top priority for public health, not only in terms of individual quality of life and well-being but also for community health.

Unlocking the health benefits of melatonin supplementation: A promising preventative and therapeutic strategy

Melatonin (MLT) is crucial in controlling human sleep-wake patterns. While it has long been recognized for regulating circadian rhythms, its demonstrated efficacy in managing various diseases has recently gained considerable attention. This review discusses MLT's potential preventative and therapeutic effects on various diseases. Several studies have focused on examining the molecular mechanisms through which MLT brings about its protective or therapeutic effects on various diseases, including cancer, obesity, coronavirus, and cardiovascular diseases. Numerous preventative and therapeutic applications of MLT have been proposed, resulting from its ability to function as an antioxidant, anti-cancer, anti-inflammatory, and immune-regulating agent. There is a need for further research to determine MLT's long-term effects on antioxidant defense systems, its preventative and therapeutic benefits, and its molecular basis.

Cocoa extract induces browning of white adipocytes and improves glucose intolerance in mice fed a high-fat diet

Cocoa extract (CE) offers several health benefits, such as antiobesity and improved glucose intolerance. However, the mechanisms remain unclear. Adipose tissue includes white adipose tissue (WAT) and brown adipose tissue. Brown adipose tissue leads to body fat reduction by metabolizing lipids to heat via uncoupling protein 1 (UCP1). The conversion of white adipocytes into brown-like adipocytes (beige adipocytes) is called browning, and it contributes to the anti-obesity effect and improved glucose tolerance. This study aimed to evaluate the effect of CE on glucose tolerance in terms of browning. We found that dietary supplementation with CE improved glucose intolerance in mice fed a high-fat diet, and it increased the expression levels of Ucp1 and browning-associated gene in inguinal WAT. Furthermore, in primary adipocytes of mice, CE induced Ucp1 expression through β3-adrenergic receptor stimulation. These results suggest that dietary CE improves glucose intolerance by inducing browning in WAT.

Irisin Protects Musculoskeletal Homeostasis via a Mitochondrial Quality Control Mechanism

Irisin, a myokine derived from fibronectin type III domain-containing 5 (FNDC5), is increasingly recognized for its protective role in musculoskeletal health through the modulation of mitochondrial quality control. This review synthesizes the current understanding of irisin's impact on mitochondrial biogenesis, dynamics, and autophagy in skeletal muscle, elucidating its capacity to bolster muscle strength, endurance, and resilience against oxidative-stress-induced muscle atrophy. The multifunctional nature of irisin extends to bone metabolism, where it promotes osteoblast proliferation and differentiation, offering a potential intervention for osteoporosis and other musculoskeletal disorders. Mitochondrial quality control is vital for cellular metabolism, particularly in energy-demanding tissues. Irisin's influence on this process is highlighted, suggesting its integral role in maintaining cellular homeostasis. The review also touches upon the regulatory mechanisms of irisin secretion, predominantly induced by exercise, and its systemic effects as an endocrine factor. While the therapeutic potential of irisin is promising, the need for standardized measurement techniques and further elucidation of its mechanisms in humans is acknowledged. The collective findings underscore the burgeoning interest in irisin as a keystone in musculoskeletal health and a candidate for future therapeutic strategies.

Neuronal lipid droplets play a conserved and sex-biased role in maintaining whole-body energy homeostasis

Lipids are essential for neuron development and physiology. Yet, the central hubs that coordinate lipid supply and demand in neurons remain unclear. Here, we combine invertebrate and vertebrate models to establish the presence and functional significance of neuronal lipid droplets (LD) in vivo. We find that LD are normally present in neurons in a non-uniform distribution across the brain, and demonstrate triglyceride metabolism enzymes and lipid droplet-associated proteins control neuronal LD formation through both canonical and recently-discovered pathways. Appropriate LD regulation in neurons has conserved and male-biased effects on whole-body energy homeostasis across flies and mice, specifically neurons that couple environmental cues with energy homeostasis. Mechanistically, LD-derived lipids support neuron function by providing phospholipids to sustain mitochondrial and endoplasmic reticulum homeostasis. Together, our work identifies a conserved role for LD as the organelle that coordinates lipid management in neurons, with implications for our understanding of mechanisms that preserve neuronal lipid homeostasis and function in health and disease.

Evaluation of serum irisin level and severity of erectile dysfunction in diabetic males: a cross sectional prospective study

BACKGROUND

Irisin is an exercise-induced myokine that alleviates endothelial dysfunction and reduces insulin resistance in type 2 diabetes mellitus (T2DM). The current study aimed to assess the serum level of irisin in T2DM men with erectile dysfunction (ED) compared to T2DM patients with normal erectile function and healthy controls, as well as investigate the association between serum irisin level and the severity of ED in T2DM patients.

PATIENTS AND METHODS

A cross-sectional study was conducted on 90 males, divided into three groups: 32 T2DM patients with ED, 24 T2DM patients without ED, and 34 healthy controls. Socio-demographic characteristics and scores of the validated Arabic version of the international Index of Erectile Function-5 (ArIIEF-5), Generalized Anxiety Disorder-7 (GAD-7) and Patient Health Questionnaire-9 (PHQ-9) were obtained. Furthermore, routine laboratory tests employed for diabetes monitoring and serum levels of total testosterone and irisin were assessed within these groups.

RESULTS

T2DM men with ED had significantly lower serum levels of irisin and testosterone, as well as a lower ArIIEF-5 score, but their GAD-7 and PHQ-9 scores were significantly higher than those without ED or controls (p < 0.001). Among T2DM men, serum irisin levels positively associated with ArIIEF-5 scores and serum testosterone (r = 0.413, p = 0.002; r = 0.936, p < 0.001, respectively) but negatively associated with glycosylated hemoglobin levels (r = -0.377, p = 0.004). Multivariate regression analysis to predict ED in T2DM patients found that GAD-7 score was the only most significant predictor for ED (ꞵ = - 1.176, standard error = 0.062, p < 0.001).

CONCLUSION

The current study had demonstrated that irisin positively correlated with the ArIIEF-5 and serum testosterone but negatively correlated with HbA1c in T2DM men. Nevertheless, further validation of these findings is necessary through cohort studies.

Short- and long-term effects of concurrent aerobic and resistance training on circulating irisin levels in overweight or obese individuals: a systematic review and meta-analysis of randomized controlled trials

Background

Concurrent training (CT) is emerging as a practical and effective approach to enhance body composition, cardiovascular function, and muscle mass, thereby elevating overall individual health. This study aims to systematically investigate the effects of short- and long-term concurrent aerobic and resistance training on circulating irisin levels in overweight or obese individuals.

Methodology

The electronic databases, including China National Knowledge Infrastructure, PubMed, Embase, Wan Fang Database, and Web of Science, were systematically searched for articles on "concurrent training" and "irisin" published from their inception to 30 November 2023. The pooled effect size was determined using standardized mean difference (SMD) and corresponding 95% confidence intervals (CIs). The study protocol received registration with the International Prospective Register of Systematic Reviews (CRD42023494163).

Results

All nine studies, encompassing a total of 264 participants, were randomized controlled trials and met the eligibility criteria. Results indicate that short- and long-term concurrent training moderately increased circulating irisin levels compared to the control group (SMD = 0.56, 95% CI [0.33-0.80], p = 0.00; I 2 = 36.6%, heterogeneity p = 0.106). Subgroup analyses revealed that both equal to or less than 10 weeks (SMD = 0.78, 95% CI [0.18-1.37], p = 0.01; I 2 = 62.3%, heterogeneity p = 0.03) and more than 10 weeks (SMD = 0.45, 95% CI [0.14-0.76], p = 0.00; I 2 = 0%, heterogeneity p = 0.54) of concurrent training significantly increased circulating irisin levels in overweight or obese individuals. There were no significant between-group differences (I 2 = 0%, p = 0.34). Additionally, concurrent training significantly increased irisin levels in overweight or obese participants (SMD = 1.06, 95% CI [0.34-1.78], p = 0.00; I 2 = 50.6%, heterogeneity p = 0.13) and in type 2 diabetes patients (SMD = 0.70, 95% CI [0.30-1.10], p = 0.00; I 2 = 0%, heterogeneity p = 0.99). However, no significant effect was observed in patients with metabolic syndrome (SMD = 0.21, 95% CI [-0.25-0.68], p = 0.37; I 2 = 38.7%, heterogeneity p = 0.18). There were significant between-group differences (I 2 = 53.9%, p = 0.11). Lastly, concurrent training significantly increased circulating irisin levels in overweight or obese individuals aged 45-60 years (SMD = 0.56, 95% CI [0.25-0.86], p = 0.00; I 2 = 6.5%, heterogeneity p = 0.38), and a significant increase in irisin levels was observed 12 h post-intervention (SMD = 0.70, 95% CI [0.35-1.05], p = 0.00; I 2 = 0%, heterogeneity p = 0.74). However, none of the above categorical variables showed significant between-group differences.

Conclusions

Short- and long-term concurrent training can effectively improve circulating irisin levels in overweight or obese individuals. However, the effects of short- and long-term concurrent training should consider the participants' health status, age, and the timing of post-exercise measurements to maximize health benefits.

Adipokines in the Crosstalk between Adipose Tissues and Other Organs: Implications in Cardiometabolic Diseases

Adipose tissue was previously regarded as a dormant organ for lipid storage until the identification of adiponectin and leptin in the early 1990s. This revelation unveiled the dynamic endocrine function of adipose tissue, which has expanded further. Adipose tissue has emerged in recent decades as a multifunctional organ that plays a significant role in energy metabolism and homeostasis. Currently, it is evident that adipose tissue primarily performs its function by secreting a diverse array of signaling molecules known as adipokines. Apart from their pivotal function in energy expenditure and metabolism regulation, these adipokines exert significant influence over a multitude of biological processes, including but not limited to inflammation, thermoregulation, immune response, vascular function, and insulin sensitivity. Adipokines are pivotal in regulating numerous biological processes within adipose tissue and facilitating communication between adipose tissue and various organs, including the brain, gut, pancreas, endothelial cells, liver, muscle, and more. Dysregulated adipokines have been implicated in several metabolic diseases, like obesity and diabetes, as well as cardiovascular diseases. In this article, we attempted to describe the significance of adipokines in developing metabolic and cardiovascular diseases and highlight their role in the crosstalk between adipose tissues and other tissues and organs.

Insights into the molecular changes of adipocyte dedifferentiation and its future research opportunities

Recent studies have challenged the traditional belief that mature fat cells are irreversibly differentiated and revealed they can dedifferentiate into fibroblast-like cells known as dedifferentiated fat (DFAT) cells. Resembling pluripotent stem cells, DFAT cells hold great potential as a cell source for stem cell therapy. However, there is limited understanding of the specific changes that occur following adipocyte dedifferentiation and the detailed regulation of this process. This review explores the epigenetic, genetic, and phenotypic alterations associated with DFAT cell dedifferentiation, identifies potential targets for clinical regulation and discusses the current applications and challenges in the field of DFAT cell research.

Plant miR6262 Modulates the Expression of Metabolic and Thermogenic Genes in Human Hepatocytes and Adipocytes

BACKGROUND

Edible plants have been linked to the mitigation of metabolic disturbances in liver and adipose tissue, including the decrease of lipogenesis and the enhancement of lipolysis and adipocyte browning. In this context, plant microRNAs could be key bioactive molecules underlying the cross-kingdom beneficial effects of plants. This study sought to explore the impact of plant-derived microRNAs on the modulation of adipocyte and hepatocyte genes involved in metabolism and thermogenesis.

METHODS

Plant miR6262 was selected as a candidate from miRBase for the predicted effect on the regulation of human metabolic genes. Functional validation was conducted after transfection with plant miRNA mimics in HepG2 hepatocytes exposed to free fatty acids to mimic liver steatosis and hMADs cells differentiated into brown-like adipocytes.

RESULTS

miR6262 decreases the expression of the predicted target RXRA in the fatty acids-treated hepatocytes and in brown-like adipocytes and affects the expression profile of critical genes involved in metabolism and thermogenesis, including PPARA, G6PC, SREBF1 (hepatocytes) and CIDEA, CPT1M and PLIN1 (adipocytes). Nevertheless, plant miR6262 mimic transfections did not decrease hepatocyte lipid accumulation or stimulate adipocyte browning.

CONCLUSIONS

these findings suggest that plant miR6262 could have a cross-kingdom regulation relevance through the modulation of human genes involved in lipid and glucose metabolism and thermogenesis in adipocytes and hepatocytes.

The Role of Secreted Frizzled-Related Protein 5 (Sfrp5) in Overweight and Obesity in Childhood and Adolescence

Background/Objective: Secreted frizzled-related protein 5 (Sfrp5) is an anti-inflammatory adipokine that has been implicated in the pathophysiology of obesity and its metabolic complications. Despite the fact that numerous studies have been carried out in adults, limited data on Sfrp5 exist for youth, especially in relation to overweight and obesity. Methods: In our study, we assessed the concentrations of Sfrp5, total oxidative (TOS) and antioxidative (TAS) status, high-sensitivity C-reactive protein (hs-CRP), and several cytokines (IL-1α, IL-1β, IL-2, IL-6, IL-8, IL-12, TNF-α) in 120 children and adolescents (mean age ± SE: 11.48 ± 0.25 years; 48 prepubertal, 72 pubertal; 74 males and 46 females) before and 1 year after the implementation of a personalized, structured, lifestyle intervention program of healthy diet, sleep, and physical exercise. Results: Based on the body mass index (BMI), participants were categorized as having morbid obesity (n = 63, 52.5%), obesity (n = 21, 17.5%), overweight (n = 22, 18.33%), or normal BMIs (n = 14, 11.67%), based on the International Obesity Task Force (IOTF) cut-off points. Following the 1-year lifestyle intervention program, a significant improvement in anthropometric measurements (BMI, BMI-z score, diastolic blood pressure, WHR, and WHtR), body-composition parameters, hepatic enzymes, lipid profile, inflammation markers, and the insulin-sensitivity profile (HbA1C, HOMA index) was observed in all subjects. Sfrp5 decreased in subjects with obesity (p < 0.01); however, it increased significantly (p < 0.05) in patients with morbid obesity. Linear regression analysis indicates that TNF-α and systolic blood pressure were the best positive predictors and hs-CRP was the best negative predictor for Sfpr5 concentration at initial assessment and glucose concentration for ΔSfrp5, while TNF-α and TAS were the best positive predictors for Sfpr5 concentration at annual assessment. Conclusions: These results indicate that Sfrp5 is associated with severe obesity and is increased following weight loss in children and adolescents with morbid obesity. It is also related to metabolic homeostasis, as well as inflammation and oxidative status.

Atomic vacancies of molybdenum disulfide nanoparticles stimulate mitochondrial biogenesis

Diminished mitochondrial function underlies many rare inborn errors of energy metabolism and contributes to more common age-associated metabolic and neurodegenerative disorders. Thus, boosting mitochondrial biogenesis has been proposed as a potential therapeutic approach for these diseases; however, currently we have a limited arsenal of compounds that can stimulate mitochondrial function. In this study, we designed molybdenum disulfide (MoS2) nanoflowers with predefined atomic vacancies that are fabricated by self-assembly of individual two-dimensional MoS2 nanosheets. Treatment of mammalian cells with MoS2 nanoflowers increased mitochondrial biogenesis by induction of PGC-1α and TFAM, which resulted in increased mitochondrial DNA copy number, enhanced expression of nuclear and mitochondrial-DNA encoded genes, and increased levels of mitochondrial respiratory chain proteins. Consistent with increased mitochondrial biogenesis, treatment with MoS2 nanoflowers enhanced mitochondrial respiratory capacity and adenosine triphosphate production in multiple mammalian cell types. Taken together, this study reveals that predefined atomic vacancies in MoS2 nanoflowers stimulate mitochondrial function by upregulating the expression of genes required for mitochondrial biogenesis.

Inter-organ cross-talk in human cancer cachexia revealed by spatial metabolomics

BACKGROUND

Cancer cachexia (CCx) presents a multifaceted challenge characterized by negative protein and energy balance and systemic inflammatory response activation. While previous CCx studies predominantly focused on mouse models or human body fluids, there's an unmet need to elucidate the molecular inter-organ cross-talk underlying the pathophysiology of human CCx.

METHODS

Spatial metabolomics were conducted on liver, skeletal muscle, subcutaneous and visceral adipose tissue, and serum from cachectic and control cancer patients. Organ-wise comparisons were performed using component, pathway enrichment and correlation network analyses. Inter-organ correlations in CCx altered pathways were assessed using Circos. Machine learning on tissues and serum established classifiers as potential diagnostic biomarkers for CCx.

RESULTS

Distinct metabolic pathway alteration was detected in CCx, with adipose tissues and liver displaying the most significant (P ≤ 0.05) metabolic disturbances. CCx patients exhibited increased metabolic activity in visceral and subcutaneous adipose tissues and liver, contrasting with decreased activity in muscle and serum compared to control patients. Carbohydrate, lipid, amino acid, and vitamin metabolism emerged as highly interacting pathways across different organ systems in CCx. Muscle tissue showed decreased (P ≤ 0.001) energy charge in CCx patients, while liver and adipose tissues displayed increased energy charge (P ≤ 0.001). We stratified CCx patients by severity and metabolic changes, finding that visceral adipose tissue is most affected, especially in cases of severe cachexia. Morphometric analysis showed smaller (P ≤ 0.05) adipocyte size in visceral adipose tissue, indicating catabolic processes. We developed tissue-based classifiers for cancer cachexia specific to individual organs, facilitating the transfer of patient serum as minimally invasive diagnostic markers of CCx in the constitution of the organs.

CONCLUSIONS

These findings support the concept of CCx as a multi-organ syndrome with diverse metabolic alterations, providing insights into the pathophysiology and organ cross-talk of human CCx. This study pioneers spatial metabolomics for CCx, demonstrating the feasibility of distinguishing cachexia status at the organ level using serum.

Vgll2 as an integrative regulator of mitochondrial function and contractility specific to skeletal muscle

During skeletal muscle adaptation to physiological or pathophysiological signals, contractile apparatus and mitochondrial function are coordinated to alter muscle fiber type. Although recent studies have identified various factors involved in modifying contractile proteins and mitochondrial function, the molecular mechanisms coordinating contractile and metabolic functions during muscle fiber transition are not fully understood. Using a gene-deficient mouse approach, our previous studies uncovered that vestigial-like family member 2 (Vgll2), a skeletal muscle-specific transcription cofactor activated by exercise, is essential for fast-to-slow adaptation of skeletal muscle. The current study provides evidence that Vgll2 plays a role in increasing muscle mitochondrial mass and oxidative capacity. Transgenic Vgll2 overexpression in mice altered muscle fiber composition toward the slow type and enhanced exercise endurance, which contradicted the outcomes observed with Vgll2 deficiency. Vgll2 expression was positively correlated with the expression of genes related to mitochondrial function in skeletal muscle, mitochondrial DNA content, and protein abundance of oxidative phosphorylation complexes. Additionally, Vgll2 overexpression significantly increased the maximal respiration of isolated muscle fibers and enhanced the suppressive effects of endurance training on weight gain. Notably, no additional alteration in expression of myosin heavy chain genes was observed after exercise, suggesting that Vgll2 plays a direct role in regulating mitochondrial function, independent of its effect on contractile components. The observed increase in exercise endurance and metabolic efficiency may be attributed to the acute upregulation of genes promoting fatty acid utilization as a direct consequence of Vgll2 activation facilitated by endurance exercise. Thus, the current study establishes that Vgll2 is an integrative regulator of mitochondrial function and contractility in skeletal muscle.

Directly targeting PRDM16 in thermogenic adipose tissue to treat obesity and its related metabolic diseases

Obesity is increasing globally and is closely associated with a range of metabolic disorders, including metabolic associated fatty liver disease, diabetes, and cardiovascular diseases. An effective strategy to combat obesity involves stimulating brown and beige adipocyte thermogenesis, which significantly enhances energy expenditure. Recent research has underscored the vital role of PRDM16 in the development and functionality of thermogenic adipocytes. Consequently, PRDM16 has been identified as a potential therapeutic target for obesity and its related metabolic disorders. This review comprehensively examines various studies that focus on combating obesity by directly targeting PRDM16 in adipose tissue.

Approach to the Patient With Suspected Silver-Russell Syndrome

Silver-Russell syndrome (SRS) is a clinical diagnosis requiring the fulfillment of ≥ 4/6 Netchine-Harbison Clinical Scoring System (NH-CSS) criteria. A score of ≥ 4/6 NH-CSS (or ≥ 3/6 with strong clinical suspicion) warrants (epi)genetic confirmation, identifiable in ∼60% patients. The approach to the investigation and diagnosis of SRS is detailed in the only international consensus guidance, published in 2016. In the intervening years, the clinical, biochemical, and (epi)genetic characteristics of SRS have rapidly expanded, largely attributable to advancing molecular genetic techniques and a greater awareness of related disorders. The most common etiologies of SRS remain loss of methylation of chromosome 11p15 (11p15LOM) and maternal uniparental disomy of chromosome 7 (upd(7)mat). Rarer causes of SRS include monogenic pathogenic variants in imprinted (CDKN1C and IGF2) and non-imprinted (PLAG1 and HMGA2) genes. Although the age-specific NH-CSS can identify more common molecular causes of SRS, its use in identifying monogenic causes is unclear. Preliminary data suggest that NH-CSS is poor at identifying many of these cases. Additionally, there has been increased recognition of conditions with phenotypes overlapping with SRS that may fulfill NH-CSS criteria but have distinct genetic etiologies and disease trajectories. This group of conditions is frequently overlooked and under-investigated, leading to no or delayed diagnosis. Like SRS, these conditions are multisystemic disorders requiring multidisciplinary care and tailored management strategies. Early identification is crucial to improve outcomes and reduce the major burden of the diagnostic odyssey for patients and families. This article aims to enable clinicians to identify key features of rarer causes of SRS and conditions with overlapping phenotypes, show a logical approach to the molecular investigation, and highlight the differences in clinical management strategies.

Rutin ameliorates HCD-induced cholesterol metabolism disorder in zebrafish larvae revealed by transcriptome and metabolome analysis

Changes in modern lifestyles have led to an increase in obesity rates. Excessive lipid accumulation leads to abnormal cholesterol metabolism, and maintaining a balanced cholesterol metabolism is essential for the normal functioning of cells and the body. Rutin belongs to the group of flavonoids with hypolipidemic, anti-inflammatory and antioxidant effects. The aim of this study was to investigate the role of rutin in cholesterol metabolism disorders induced by a high cholesterol diet in zebrafish larvae. The trial was divided into five groups: Normal diet (ND), 5 % high cholesterol diet (HCD), 5 % high cholesterol diet with 80 μg/g ezetimibe diet (EZE), 5 % high cholesterol diet with 5 % rutin diet (RL-HCD), and 5 % high cholesterol diet with 10 % rutin diet (RH-HCD). Zebrafish larvae at 5 dpf were randomly divided into five groups and continuously fed different diets for 10 days, after 10 days zebrafish samples were collected for subsequent experiments. Body length, body width, oil red O, and Nile red staining were measured to detect biochemical indexes, analyze inflammatory response and lipid accumulation. Vascular endothelial injury was assessed by stereofluorescence microscopy and ELISA. In order to study the protective effect of rutin in zebrafish with cholesterol metabolism disorder induced by HCD, RNA-seq and LC-MS/MS nontargeted metabolomics were employed. The results indicate that HCD led to an increase in the body length and width of zebrafish. The HCD group induced an increase in body length and width, lipid accumulation, and exacerbated inflammation. Additionally, vascular damage and abnormal expression of endothelial cell markers were observed. Rutin lowered lipid levels in zebrafish fed an HCD, reduced inflammation, and protected endothelial cells. The RNA-seq and metabolomic analysis combined demonstrated that rutin effectively ameliorates the disorder of cholesterol metabolism in vivo by reducing cholesterol synthesis and promoting cholesterol transport.

PRDM3/16 regulate chromatin accessibility required for NKX2-1 mediated alveolar epithelial differentiation and function

While the critical role of NKX2-1 and its transcriptional targets in lung morphogenesis and pulmonary epithelial cell differentiation is increasingly known, mechanisms by which chromatin accessibility alters the epigenetic landscape and how NKX2-1 interacts with other co-activators required for alveolar epithelial cell differentiation and function are not well understood. Combined deletion of the histone methyl transferases Prdm3 and Prdm16 in early lung endoderm causes perinatal lethality due to respiratory failure from loss of AT2 cells and the accumulation of partially differentiated AT1 cells. Combination of single-cell RNA-seq, bulk ATAC-seq, and CUT&RUN data demonstrate that PRDM3 and PRDM16 regulate chromatin accessibility at NKX2-1 transcriptional targets critical for perinatal AT2 cell differentiation and surfactant homeostasis. Lineage specific deletion of PRDM3/16 in AT2 cells leads to lineage infidelity, with PRDM3/16 null cells acquiring partial AT1 fate. Together, these data demonstrate that NKX2-1-dependent regulation of alveolar epithelial cell differentiation is mediated by epigenomic modulation via PRDM3/16.

Development and validation of an MRI and clinicopathological factors prediction model for low anterior resection syndrome in anterior resection of middle and low rectal cancer

Objective

To validate the predictive power of newly developed magnetic resonance (MR) morphological and clinicopathological risk models in predicting low anterior resection syndrome (LARS) 6 months after anterior resection of middle and low rectal cancer (MLRC).

Methods

From May 2018 to January 2021, 236 patients with MLRC admitted to two hospitals (internal and external validation) were included. MR images, clinicopathological data, and LARS scores (LARSS) were collected. Tumor morphology data included longitudinal involvement length, maximum tumor diameter, proportion of tumor to circumference of the intestinal wall, tumor mesorectal infiltration depth, circumferential margin status, and distance between the tumor and anal margins. Pelvic measurements included anorectal angle, mesenterial volume (MRV), and pelvic volume. Univariate and multivariate logistic regression was used to obtain independent risk factors of LARS after anterior resection Then, the prediction model was constructed, expressed as a nomogram, and its internal and external validity was assessed using receiver operating characteristic curves.

Results

The uni- and multivariate analysis revealed distance between the tumor and anal margins, MRV, pelvic volume, and body weight as significant independent risk factors for predicting LARS. From the nomogram, the area under the curve (AUC), sensitivity, and specificity were 0.835, 75.0 %, and 80.4 %, respectively. The AUC, sensitivity, and specificity in the external validation group were 0.874, 83.3 %, and 91.7 %, respectively.

Conclusion

This study shows that MR imaging and clinicopathology presented by a nomogram can strongly predict LARSS, which can then individually predict LARS 6 months after anterior resection in patients with MLRC and facilitate clinical decision-making.

Clinical relevance statement

We believe that our study makes a significant contribution to the literature. This method of predicting postoperative anorectal function by preoperative measurement of MRV provides a new tool for clinicians to study LARS.

Melatonin rescues pregnant female mice and their juvenile offspring from high fat diet-induced alzheimer disease neuropathy

High fat diet (HFD) is a prime factor, which contributes to the present epidemic of metabolic syndrome. Prolonged intake of HFD induces oxidative stress (OS) that in turn causes neuroinflammation, neurodegeneration, insulin resistance, amyloid burden, synaptic dysfunction and cognitive impairment hence leading to Alzheimer's disease neuropathy. Melatonin (secreted by the Pineal gland) has the potential to nullify the toxic effects of reactive oxygen species (ROS) and have been shown to ameliorate various complications induced by HFD in rodent models. This study aimed to assess the neurotherapeutic effects of melatonin on HFD-induced neuroinflammation and neurodegeneration mediated by OS in pregnant female mice and their offspring. Western blotting, immunohistochemistry and antioxidant enzyme assays were used for quantification of samples from the hippocampal region of the brain of pregnant albino mice and their offspring. Short- and long-term memory was assessed by Y-maze and Morris Water Maze tests. HFD significantly induced OS leading to AD like neuropathology in the pregnant mice and their offspring while melatonin administration simultaneously with the HFD significantly prevented this neuropathy. This study reports that melatonin exerts these effects through the stimulation of SIRT1/Nrf2/HO-1 pathway that in turn reduces the HFD-induced OS and its downstream signaling. In conclusion melatonin prevents HFD-induced multiple complications that ultimately leads to the memory dysfunction in pregnant female mice and their successive generation via activation of SIRT1/Nrf2 signaling pathway.

NR4A1-mediated regulation of lipid droplets in progesterone synthesis in goat luteal cells†

Nuclear receptor NR4A1 is a key factor in glycolipid metabolism and steroidogenesis, while lipid droplets serve as crucial dynamic organelles for lipid metabolism in luteal cells. To investigate the effects of NR4A1 on lipid droplet metabolism and progesterone (P4) synthesis in goat corpus luteum in vitro, luteal cells from the middle-cyclic corpus luteum were isolated and treated with Cytosporone B (CSNB, an agonist) or siRNA of NR4A1. Results showed that both low (1 μM) and high (50 μM) concentrations of CSNB promoted lipid droplet accumulation, while NR4A1 knockdown reduced lipid droplet content. CSNB increased while siNR4A1 decreased total cholesterol content; however, CSNB and siNR4A1 did not change triglyceride content. CSNB increased the expression of perilipins at mRNA and protein levels, also increased LDLR, SCARB1, SREBFs, and HMGCR mRNA abundance. Treatment with siNR4A1 revealed opposite results of CSNB, except for HMCGR and SREBF2. For steroidogenesis, 1 μM CSNB increased, but 50 μM CSNB inhibited P4 synthesis, NR4A1 knockdown also reduced the P4 level. Further analysis demonstrated that 1 μM CSNB increased the protein levels of StAR, HSD3B, and P-HSL, while 50 μM CSNB decreased StAR, HSD3B, and CYP11A1 protein levels. Moreover, 50 μM CSNB impaired active mitochondria, reduced the BCL2, and increased DRP1, Caspase 3, and cleaved-Caspase 3 protein levels. siNR4A1 consistently downregulated the P-HSL/HSL ratio and the steroidogenic protein levels. In conclusion, NR4A1-mediated lipid droplets are involved in the regulation of progesterone synthesis in goat luteal cells.

Sphingosine kinase 1 is induced by glucocorticoids in adipose derived stem cells and enhances glucocorticoid mediated signaling in adipose expansion

Sphingosine kinase 1 (SphK1) plays a crucial role in regulating metabolic pathways within adipocytes and is elevated in the adipose tissue of obese mice. While previous studies have reported both pro- and inhibitory effects of SphK1 and its product, sphingosine-1-phosphate (S1P), on adipogenesis, the precise mechanisms remain unclear. This study explores the timing and downstream effects of SphK1/S1P expression and activation during in vitro adipogenesis. We demonstrate that the synthetic glucocorticoid dexamethasone robustly induces SphK1 expression, suggesting its involvement in glucocorticoid-dependent signaling during adipogenesis. Notably, the activation of C/EBPδ, a key gene in early adipogenesis and a target of glucocorticoids, is diminished in SphK1-/- adipose-derived stem cells (ADSCs). Furthermore, glucocorticoid administration promotes adipose tissue expansion via SphK1 in a depot-specific manner. Although adipose expansion still occurs in SphK1-/- mice, it is significantly reduced. These findings indicate that while SphK1 is not essential for adipogenesis, it enhances early gene activation, thereby facilitating adipose tissue expansion.

Role of Irisin in exercise training-regulated endoplasmic reticulum stress, autophagy and myogenesis in the skeletal muscle after myocardial infarction

Patients with heart failure (HF) are often accompanied by skeletal muscle abnormalities, which can lead to exercise intolerance and compromise daily activities. Irisin, an exercise training (ET) -induced myokine, regulates energy metabolism and skeletal muscle homeostasis. However, the precise role of Irisin in the benefits of ET on inhibiting skeletal muscle atrophy, particularly on endoplasmic reticulum (ER) stress, autophagy, and myogenesis following myocardial infarction (MI) remains unclear. In this study, we investigated the expression of Irisin protein in wild-type mice with MI, and assessed its role in the beneficial effects of ET using an Fndc5 knockout mice. Our findings revealed that MI reduced muscle fiber cross-sectional area (CSA), while downregulating the expression of Irisin, PGC-1α and SOD1. Concurrently, MI elevated the levels of ER stress and apoptosis, and inhibited autophagy in skeletal muscle. Conversely, ET mitigated ER stress and apoptosis in the skeletal muscle of infarcted mice. Notably, Fndc5 knockout worsened MI-induced ER stress and apoptosis, suppressed autophagy and myogenesis, and abrogated the beneficial effects of ET. In conclusion, our findings highlight the role of Irisin in the ET-mediated alleviation of skeletal muscle abnormalities. This study provides valuable insights into MI-induced muscle abnormalities and enhances our understanding of exercise rehabilitation mechanisms in clinical MI patients.

Bidirectional Effect of Long-Term Δ9-Tetrahydrocannabinol Treatment on mTOR Activity and Metabolome

Brain aging is associated with cognitive decline, reduced synaptic plasticity, and altered metabolism. The activity of mechanistic target of rapamycin (mTOR) has a major impact on aging by regulating cellular metabolism. Although reduced mTOR signaling has a general antiaging effect, it can negatively affect the aging brain by reducing synaptogenesis and thus cognitive functions. Increased mTOR activity facilitates aging and is responsible for the amnestic effect of the cannabinoid receptor 1 agonist Δ9-tetrahydrocannabinol (THC) in higher doses. Long-term low-dose Δ9-THC had an antiaging effect on the brain by restoring cognitive abilities and synapse densities in old mice. Whether changes in mTOR signaling and metabolome are associated with its positive effects on the aging brain is an open question. Here, we show that Δ9-THC treatment has a tissue-dependent and dual effect on mTOR signaling and the metabolome. In the brain, Δ9-THC treatment induced a transient increase in mTOR activity and in the levels of amino acids and metabolites involved in energy production, followed by an increased synthesis of synaptic proteins. Unexpectedly, we found a similar reduction in the mTOR activity in adipose tissue and in the level of amino acids and carbohydrate metabolites in blood plasma as in animals on a low-calorie diet. Thus, long-term Δ9-THC treatment first increases the level of energy and synaptic protein production in the brain, followed by a reduction in mTOR activity and metabolic processes in the periphery. Our study suggests that a dual effect on mTOR activity and the metabolome could be the basis for an effective antiaging and pro-cognitive medication.

Effects of Omega-3 Polyunsaturated Fatty Acids on the Formation of Adipokines, Cytokines, and Oxylipins in Retroperitoneal Adi-Pose Tissue of Mice

Oxylipins and specialized pro-resolving lipid mediators (SPMs) derived from polyunsaturated fatty acids (PUFAs) are mediators that coordinate an active process of inflammation resolution. While these mediators have potential as circulating biomarkers for several disease states with inflammatory components, the source of plasma oxylipins/SPMs remains a matter of debate but may involve white adipose tissue (WAT). Here, we aimed to investigate to what extent high or low omega (n)-3 PUFA enrichment affects the production of cytokines and adipokines (RT-PCR), as well as oxylipins/SPMs (liquid chromatography-tandem mass spectrometry) in the WAT of mice during lipopolysaccharide (LPS)-induced systemic inflammation (intraperitoneal injection, 2.5 mg/kg, 24 h). For this purpose, n-3 PUFA genetically enriched mice (FAT-1), which endogenously synthesize n-3 PUFAs, were compared to wild-type mice (WT) and combined with n-3 PUFA-sufficient or deficient diets. LPS-induced systemic inflammation resulted in the decreased expression of most adipokines and interleukin-6 in WAT, whereas the n-3-sufficient diet increased them compared to the deficient diet. The n-6 PUFA arachidonic acid was decreased in WAT of FAT-1 mice, while n-3 derived PUFAs (eicosapentaenoic acid, docosahexaenoic acid) and their metabolites (oxylipins/SPMs) were increased in WAT by genetic and nutritional n-3 enrichment. Several oxylipins/SPMs were increased by LPS treatment in WAT compared to PBS-treated controls in genetically n-3 enriched FAT-1 mice. Overall, we show that WAT may significantly contribute to circulating oxylipin production. Moreover, n-3-sufficient or n-3-deficient diets alter adipokine production. The precise interplay between cytokines, adipokines, and oxylipins remains to be further investigated.

The Therapeutic Potential of Theobromine in Obesity: A Comprehensive Review

Obesity, characterized by chronic low-grade inflammation, is a significant health concern. Phytochemicals found in plants are being explored for therapeutic use, particularly in combating obesity. Among these, theobromine, commonly found in cocoa and chocolate, shows promise. Although not as extensively studied as caffeine, theobromine exhibits positive effects on human health. It improves lipid profiles, aids in asthma treatment, lowers blood pressure, regulates gut microbiota, reduces tumor formation, moderates blood glucose levels, and acts as a neuroprotective agent. Studies demonstrate its anti-obesity effects through mechanisms such as browning of white adipose tissue, activation of brown adipose tissue, anti-inflammatory properties, and reduction of oxidative stress. This study aims to suggest theobromine as a potential therapeutic agent against obesity-related complications.

Myosteatosis and the clinical outcomes of patients with liver cirrhosis: A meta-analysis

OBJECTIVES

This study aimed to examine the potential correlation between myosteatosis and the prognosis of patients diagnosed with liver cirrhosis by a meta-analysis.

METHODS

Cohort studies of relevance were acquired through comprehensive searches of the Medline, Web of Science, and Embase databases. To account for heterogeneity, a random-effects model was employed to combine the findings.

RESULTS

The meta-analysis included 10 retrospective and four prospective cohort studies, encompassing a total of 4287 patients diagnosed with cirrhosis. The pooled findings indicated a notable decline in transplant-free survival (TFS) among individuals with liver cirrhosis and myosteatosis compared to those without this condition (risk ratio: 1.94; 95% confidence interval: 1.61 to 2.34, p < 0.001; I2 = 49%). The predefined subgroup analyses demonstrated consistent findings across various categories, including Asian and non-Asian studies, prospective and retrospective cohort studies, patients with cirrhosis overall and those who underwent transjugular intrahepatic portosystemic shunt, studies with different follow-up durations (< or ≥ 24 months), studies employing univariate and multivariate analyses, and studies with and without an adjustment for sarcopenia (p > 0.05 for all subgroup differences). Additionally, Egger's regression test indicated the presence of significant publication bias (p = 0.044). However, trim-and-fill analysis by including three hypothesized studies showed consistent results.

CONCLUSIONS

The presence of myosteatosis in individuals diagnosed with liver cirrhosis may potentially be linked to a poor TFS prognosis. Further investigations are required to ascertain whether enhancing myosteatosis could potentially yield a survival advantage for this particular patient population.

Hypoxia in Human Obesity: New Insights from Inflammation towards Insulin Resistance-A Narrative Review

Insulin resistance (IR), marked by reduced cellular responsiveness to insulin, and obesity, defined by the excessive accumulation of adipose tissue, are two intertwined conditions that significantly contribute to the global burden of cardiometabolic diseases. Adipose tissue, beyond merely storing triglycerides, acts as an active producer of biomolecules. In obesity, as adipose tissue undergoes hypertrophy, it becomes dysfunctional, altering the release of adipocyte-derived factors, known as adipokines. This dysfunction promotes low-grade chronic inflammation, exacerbates IR, and creates a hyperglycemic, proatherogenic, and prothrombotic environment. However, the fundamental cause of these phenomena remains unclear. This narrative review points to hypoxia as a critical trigger for the molecular changes associated with fat accumulation, particularly within visceral adipose tissue (VAT). The activation of hypoxia-inducible factor-1 (HIF-1), a transcription factor that regulates homeostatic responses to low oxygen levels, initiates a series of molecular events in VAT, leading to the aberrant release of adipokines, many of which are still unexplored, and potentially affecting peripheral insulin sensitivity. Recent discoveries have highlighted the role of hypoxia and miRNA-128 in regulating the insulin receptor in visceral adipocytes, contributing to their dysfunctional behavior, including impaired glucose uptake. Understanding the complex interplay between adipose tissue hypoxia, dysfunction, inflammation, and IR in obesity is essential for developing innovative, targeted therapeutic strategies.

The dual nature of DNA damage response in obesity and bariatric surgery-induced weight loss

This novel study applies targeted functional proteomics to examine tissues and cells obtained from a cohort of individuals with severe obesity who underwent bariatric surgery (BS), using a Reverse-Phase Protein Array (RPPA). In obese individuals, visceral adipose tissue (VAT), but not subcutaneous adipose tissue (SAT), shows activation of DNA damage response (DDR) markers including ATM, ATR, histone H2AX, KAP1, Chk1, and Chk2, alongside senescence markers p16 and p21. Additionally, stress-responsive metabolic markers, such as survivin, mTOR, and PFKFB3, are specifically elevated in VAT, suggesting both cellular stress and metabolic dysregulation. Conversely, peripheral blood mononuclear cells (PBMCs), while exhibiting elevated mTOR and JNK levels, did not present significant changes in DDR or senescence markers. Following BS, unexpected increases in phosphorylated ATM, ATR, and KAP1 levels, but not in Chk1 and Chk2 nor in senescence markers, were observed. This was accompanied by heightened levels of survivin and mTOR, along with improvement in markers of mitochondrial quality and health. This suggests that, following BS, pro-survival pathways involved in cellular adaptation to various stressors and metabolic alterations are activated in circulating PBMCs. Moreover, our findings demonstrate that the DDR has a dual nature. In the case of VAT from individuals with obesity, chronic DDR proves to be harmful, as it is associated with senescence and chronic inflammation. Conversely, after BS, the activation of DDR proteins in PBMCs is associated with a beneficial survival response. This response is characterized by metabolic redesign and improved mitochondrial biogenesis and functionality. This study reveals physiological changes associated with obesity and BS that may aid theragnostic approaches.

New insights into lipid and fatty acid metabolism from Raman spectroscopy

One of the challenges facing biology is to understand metabolic events at a single cellular level. While approaches to examine dynamics of protein distribution or report on spatiotemporal location of signalling molecules are well-established, tools for the dissection of metabolism in single living cells are less common. Advances in Raman spectroscopy, such as stimulated Raman scattering (SRS), are beginning to offer new insights into metabolic events in a range of experimental systems, including model organisms and clinical samples, and across a range of disciplines. Despite the power of Raman imaging, it remains a relatively under-used technique to approach biological problems, in part because of the specialised nature of the analysis. To raise the profile of this method, here we consider some key studies which illustrate how Raman spectroscopy has revealed new insights into fatty acid and lipid metabolism across a range of cellular systems. The powerful and non-invasive nature of this approach offers a new suite of tools for biomolecular scientists to address how metabolic events within cells informs on or underpins biological function. We illustrate potential biological applications, discuss some recent advances, and offer a direction of travel for metabolic research in this area.

Comparative efficacy of different exercise modalities on metabolic profiles and liver functions in non-alcoholic fatty liver disease: a network meta-analysis

Objective

Research evidence suggests that exercise is a potent therapeutic strategy for non-alcoholic fatty liver disease (NAFLD). Many investigations have delved into the curative potential of diverse exercise regimens on NAFLD. This investigation synthesizes findings from randomized controlled trials via a network meta-analysis to evaluate the efficacy of exercise-based interventions on NAFLD.

Methods

We conducted a search across five electronic databases (Web of Science, EMBASE, PubMed, SCOPUS, and CNKI)to identify randomized controlled trials (RCTs) comparing the effects of different exercise modalities on metabolic profiles and liver functions in patients with NAFLD. The literature search was comprehensive up to 15, December 2023. The selected studies were subjected to a rigorous quality appraisal and risk of bias analysis in accordance with the Cochrane Handbook's guidelines, version 5.1.0. We employed Stata/MP 17 for the network meta-analysis, presenting effect sizes as standardized mean differences (SMD).

Results

This study aggregated results from 28 studies, involving a total of 1,606 participants. The network meta-analysis revealed that aerobic exercise was the most effective intervention for improving BMI in patients with NAFLD, demonstrating a significant decrease in BMI (-0.72, 95%CI: -0.98 to -0.46; p < 0.05; Surface Under the Cumulative Ranking (SUCRA) = 79.8%). HIIT was the top intervention for enhancing HDL-C (0.12, 95% CI: 0.04 to 0.20; p < 0.05; SUCRA = 76.1%). Resistance exercise was the most effective for reducing LDL-C (-0.20, 95% CI: -0.33 to -0.06; p < 0.05; SUCRA = 69.7%). Mind-body exercise showed superior effectiveness in improving TC (-0.67, 95% CI: -1.10 to -0.24; p < 0.05; SUCRA = 89.7%), TG = -0.67, 95% CI: -1.10 to -0.24; p < 0.05; SUCRA = 99.6%), AST (-8.07, 95% CI: -12.88 to -3.25; p < 0.05; SUCRA = 76.1%), ALT (-12.56, 95% CI: -17.54 to -7.58; p < 0.05; SUCRA = 99.5%), and GGT (-13.77, 95% CI: -22.00 to -5.54; p < 0.05; SUCRA = 81.8%).

Conclusion

This network meta-analysis demonstrates that exercise interventions positively affect various metabolic profiles and liver functions in NAFLD patients. Mind-body exercises are particularly effective, surpassing other exercise forms in improving metabolic profiles and liver functions.

Systematic Review Registration

https://www.crd.york.ac.uk/PROSPERO/, identifier registration number CRD42024526332.

Irisin attenuates acute glaucoma-induced neuroinflammation by activating microglia-integrin αVβ5/AMPK and promoting autophagy

Neuroinflammation, characterized by microglial activation and the release of multiple inflammatory mediators, is a key factor in acute glaucomatous injury leading to retinal ganglion cell (RGC) death and ultimately irreversible vision loss. Irisin, a novel exercise-induced myokine, has demonstrated anti-inflammatory activity in ischemia/reperfusion injuries across multiple organs and has displayed a significant neuroprotective role in experimental stroke disease models. This study examined the protective impact of irisin and investigated its potential mechanism involved in this process utilizing an acute ocular hypertension (AOH)-induced retinal injury model in mice and a microglia inflammation model induced by lipopolysaccharide (LPS). There was a transient downregulation of irisin in the retina after AOH injury, with parallel emergence of retinal neuroinflammation and RGC death. Irisin attenuated retinal and optic nerve damage and promotes the phenotypic conversion of microglia from M1 to M2. Mechanistically, irisin significantly upregulated the expression of integrin αVβ5, p-AMPK, and autophagy-related markers. Integrin αVβ5 was highly expressed on microglia but hardly expressed on RGC. The integrin αVβ5 inhibitor cilengitide, the AMPK inhibitor dorsomorphin, and the autophagy inhibitor 3-Methyladenine (3-MA) blocked the neuroprotective effects of irisin. Our results suggest irisin attenuates acute glaucoma-induced neuroinflammation and RGC death by activating integrin αVβ5/AMPK in microglia and promoting autophagy. It should be considered a potential neuroprotective therapy for acute glaucoma.

The effect of 60 days of 6° head-down-tilt bed rest on circulating adropin, irisin, retinol binding protein-4 (RBP4) and individual metabolic responses in young, healthy males

Background

Alterations in the circulating concentrations and target-tissue action of organokines underpin the development of insulin resistance in microgravity and gravity deprivation. The purpose of this study was to examine changes in circulating adropin, irisin, retinol binding protein-4 (RBP4), and the metabolic response of healthy young males following 60 days of 6° head-down-tilt (HDT) bed rest, with and without reactive jump training (RJT), to explore links with whole-body and tissue-specific insulin sensitivity. To our knowledge, this is the first time that adropin, irisin, and RBP4 have been studied in HDT bed rest.

Methods

A total of 23 male subjects (29 ± 6 years, 181 ± 6 cm, 77 ± 7 kg) were exposed to 60 days of 6° HDT bed rest and randomized to a control (CTRL, n = 11) or a RJT (JUMP, n = 12) group (48 sessions with ≤4 min total training time per session). Circulating adropin, irisin, and RBP4 were quantified in fasting serum before and after HDT bed rest. A subanalysis was performed a posteriori to investigate individual metabolic responses post-HDT bed rest based on subjects that showed an increase or decrease in whole-body insulin sensitivity (Matsuda index).

Results

There were significant main effects of time, but not group, for decreases in adropin, irisin, Matsuda index, and liver insulin sensitivity following HDT bed rest (p < 0.05), whereas RBP4 did not change. The subanalysis identified that in a subgroup with decreased whole-body insulin sensitivity (n = 17), RBP4 increased significantly, whereas adropin, irisin, and liver insulin sensitivity were all decreased significantly following HDT bed rest. Conversely, in a subgroup with increased whole-body insulin sensitivity (n = 6), liver insulin sensitivity increased significantly after HDT bed rest, whereas adropin, irisin, and RBP4 did not change.

Conclusion

Investigating individual metabolic responses has provided insights into changes in circulating adropin, irisin, RBP4, in relation to insulin sensitivity following HDT bed rest. We conclude that adropin, irisin, and RBP4 are candidate biomarkers for providing insights into whole-body and tissue-specific insulin sensitivity to track changes in physiological responsiveness to a gravity deprivation intervention in a lean male cohort.

Skeletal Muscle SIRT3 Deficiency Contributes to Pulmonary Vascular Remodeling in Pulmonary Hypertension Due to Heart Failure With Preserved Ejection Fraction

BACKGROUND

Pulmonary hypertension (PH) is a major complication linked to adverse outcomes in heart failure with preserved ejection fraction (HFpEF), yet no specific therapies exist for PH associated with HFpEF (PH-HFpEF). We have recently reported on the role of skeletal muscle SIRT3 (sirtuin-3) in modulation of PH-HFpEF, suggesting a novel endocrine signaling pathway for skeletal muscle modulation of pulmonary vascular remodeling.

METHODS

Using skeletal muscle-specific Sirt3 knockout mice (Sirt3skm-/-) and mass spectrometry-based comparative secretome analysis, we attempted to define the processes by which skeletal muscle SIRT3 defects affect pulmonary vascular health in PH-HFpEF.

RESULTS

Sirt3skm-/- mice exhibited reduced pulmonary vascular density accompanied by pulmonary vascular proliferative remodeling and elevated pulmonary pressures. Comparative analysis of secretome by mass spectrometry revealed elevated secretion levels of LOXL2 (lysyl oxidase homolog 2) in SIRT3-deficient skeletal muscle cells. Elevated circulation and protein expression levels of LOXL2 were also observed in plasma and skeletal muscle of Sirt3skm-/- mice, a rat model of PH-HFpEF, and humans with PH-HFpEF. In addition, expression levels of CNPY2 (canopy fibroblast growth factor signaling regulator 2), a known proliferative and angiogenic factor, were increased in pulmonary artery endothelial cells and pulmonary artery smooth muscle cells of Sirt3skm-/- mice and animal models of PH-HFpEF. CNPY2 levels were also higher in pulmonary artery smooth muscle cells of subjects with obesity compared with nonobese subjects. Moreover, treatment with recombinant LOXL2 protein promoted pulmonary artery endothelial cell migration/proliferation and pulmonary artery smooth muscle cell proliferation through regulation of CNPY2-p53 signaling. Last, skeletal muscle-specific Loxl2 deletion decreased pulmonary artery endothelial cell and pulmonary artery smooth muscle cell expression of CNPY2 and improved pulmonary pressures in mice with high-fat diet-induced PH-HFpEF.

CONCLUSIONS

This study demonstrates a systemic pathogenic impact of skeletal muscle SIRT3 deficiency in remote pulmonary vascular remodeling and PH-HFpEF. This study suggests a new endocrine signaling axis that links skeletal muscle health and SIRT3 deficiency to remote CNPY2 regulation in the pulmonary vasculature through myokine LOXL2. Our data also identify skeletal muscle SIRT3, myokine LOXL2, and CNPY2 as potential targets for the treatment of PH-HFpEF.

Swimming alleviates myocardial fibrosis of type II diabetic rats through activating miR-34a-mediated SIRT1/PGC-1α/FNDC5 signal pathway

Myocardial fibrosis can trigger heart failure in diabetic cardiomyopathy (DCM), and irisin, an exercise-induced myokine, may have a beneficial effect on cardiac function. However, the specific molecular mechanism between exercise and irisin in the diabetic heart remains not fully explored. This study aimed to investigate how miR-34a mediates exercise-induced irisin to ameliorate myocardial fibrosis and its underlying mechanisms. Type 2 diabetes mellitus (T2DM) with DCM was induced in adult male rats with high-fat diet and streptozotocin injection. The DCM rats were subjected to swimming (60 min/d) and recombinant irisin (r-irisin, 500 μg/kg/d) interventions for 8 weeks, respectively. Cardiac function, cardiomyocyte structure, myocardial fibrosis and its correlated gene and protein expression were analyzed. Swimming intervention alleviated insulin resistance, myocardial fibrosis, and myocardial hypertrophy, and promoted blood glucose homeostasis in T2DM model rats. This improvement was associated with irisin upregulation and miR-34a downregulation in the myocardium, thus enhancing cardiac function. Similar efficacy was observed via intraperitoneal injection of exogenous recombinant irisin. Inhibition of miR-34a in vivo exhibited an anti-myocardial fibrotic effect by promoting irisin secretion through activating sirtuin 1 (SIRT1)/peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α)/fibronectin type III domain-containing protein 5 (FNDC5) signal pathway and downregulating myocardial fibrosis markers (collagen I, collagen III, and transforming growth factor-β1). Therefore, swimming-induced irisin has the potential therapeutic effect on diabetic myocardial fibrosis through activating the miR-34a-mediated SIRT1/PGC-1α/FNDC5 signal pathway.

Evidence of Browning and Inflammation Features in Visceral Adipose Tissue of Women with Endometriosis

BACKGROUND

Patients with endometriosis tend to have a low body mass index, suggesting an inverse relationship between body fat and risk of disease. This is supported by evidence that miRNAs differentially expressed in endometriosis induce browning of pre-adipocytes in vitro. Thus, we hypothesize that endometriosis may underlie adipose tissue (AT) dysfunction and browning.

AIMS

Identify inflammation and browning processes in AT collected from endometriosis patients.

METHODS

Visceral and subcutaneous AT samples were obtained during endometriosis (n = 32) or uterine myoma (n = 14; controls) surgery. Blood catecholamines were determined by high-performance liquid chromatography while IL-6 and TGF-β levels were quantified by ELISA. Adipocyte cross-sectional areas were analyzed in H&E-stained sections by computer-assisted morphometry. Macrophages (F4/80; Galectin-3) and browning activation (UCP-1; PGC-1α) in tissues were identified by dual label immunofluorescence. Expression of inflammatory (IL-6; MCP-1; Galectin-3; CD206; TIMP1; TGF-β) and browning-related (UCP-1; PGC-1α; DIO2; CITED1; CIDEA; TMEM26; TBX1; PRDM16; PPAR-γ) molecules in AT were assessed by RT-PCR and Western blotting.

RESULTS

Compared to controls, patients presented smaller adipocytes, especially in VAT, and lower norepinephrine levels. Serum IL-6, but not TGF-β, was increased in patients. UCP-1, PGC-1α, IL-6, and MCP-1 were upregulated in VAT from endometriosis women, which also evidenced a reduction of CD206, relative to controls. However, no differences were found in mRNA expression of IL-6, TIMP1, and TGF-β nor Galectin-3 protein levels. In SAT, protein expression remained unchanged between patients and controls.

CONCLUSIONS

Our findings support an endometriosis' role as a pro-catabolic state along with local signals of VAT browning and inflammation.

Mitochondrial topoisomerase I (Top1MT) prevents the onset of metabolic dysfunction-associated steatohepatitis (MASH) in mice

High fat (HF) diet is a major factor in the development of metabolic dysfunction-associated steatotic liver disease (MASLD) and steatohepatis (MASH), and mitochondria have been proposed to play a role in the pathogenesis of HF diet-induced MASH. Because Mitochondrial topoisomerase I (Top1MT) is exclusively present in mitochondria and Top1MT knock-out mice are viable, we were able to assess the role of Top1MT in the development of MASH. We show that after 16 weeks of HF diet, mice lacking Top1MT are prone to the development of severe MASH characterized by liver steatosis, lobular inflammation and hepatocyte damage. Mice lacking Top1MT also show prominent mitochondrial dysfunction, ROS production and mitochondrial DNA (mtDNA) release, accompanied by hepatic inflammation and fibrosis. In summary, our study demonstrates the importance of Top1MT in sustaining hepatocyte functions and suppressing MASH.

Endothelin-1 down-regulates nuclear factor erythroid 2-related factor-2 and contributes to perivascular adipose tissue dysfunction in obesity

Perivascular adipose tissue (PVAT) negatively regulates vascular muscle contraction. However, in the context of obesity, the PVAT releases vasoconstrictor substances that detrimentally affect vascular function. A pivotal player in this scenario is the peptide endothelin-1 (ET-1), which induces oxidative stress and disrupts vascular function. The present study postulates that obesity augments ET-1 production in the PVAT, decreases the function of the nuclear factor erythroid 2-related factor-2 (Nrf2) transcription factor, further increasing reactive oxygen species (ROS) generation, culminating in PVAT dysfunction. Male C57BL/6 mice were fed either a standard or a high-fat diet for 16 weeks. Mice were also treated with saline or a daily dose of 100 mg·kg-1 of the ETA and ETB receptor antagonist Bosentan, for 7 days. Vascular function was evaluated in thoracic aortic rings, with and without PVAT. Mechanistic studies utilized PVAT from all groups and cultured WT-1 mouse brown adipocytes. PVAT from obese mice exhibited increased ET-1 production, increased ECE1 and ETA gene expression, loss of the anticontractile effect, as well as increased ROS production, decreased Nrf2 activity, and downregulated expression of Nrf2-targeted antioxidant genes. PVAT of obese mice also exhibited increased expression of Tyr216-phosphorylated-GSK3β and KEAP1, but not BACH1 - negative Nrf2 regulators. Bosentan treatment reversed all these effects. Similarly, ET-1 increased ROS generation and decreased Nrf2 activity in brown adipocytes, events mitigated by BQ123 (ETA receptor antagonist). These findings place ET-1 as a major contributor to PVAT dysfunction in obesity and highlight that pharmacological control of ET-1 effects restores PVAT's cardiovascular protective role.