Modulation of NRF2/KEAP1 Signaling by Phytotherapeutics in Periodontitis

Periodontitis affects up to 40% of adults over 60 years old and is a consequence of gingivitis. Periodontitis is characterized by a chronic inflammation, periodontal damage, and alveolar bone resorption. The nuclear factor erythroid 2-related factor 2 (NFE2L2 or NRF2)/Kelch-like ECH-Associated Protein 1 (KEAP1) (NRF2/KEAP1) signaling pathway plays a key role in periodontitis by modulating redox balance and inflammation of the periodontium. However, NRF2 expression is decreased in gingival tissues of patients with periodontitis while oxidative stress is significantly increased in this pathology. Oxidative stress and lipopolysaccharide (LPS) produced by gram-negative bacteria favor the production of inflammatory causing periodontal inflammation and favoring alveolar bone. In this review, we analyzed the current literature regarding the role of natural and synthetic compounds in modulating the NRF2/KEAP1 pathway in in vitro and in vivo models of periodontitis in order to evaluate new potential treatments of periodontitis that can improve the outcome of this disease.

Parathyroidectomy reduces inflammatory cytokines and increases vitamin D metabolites in patients with primary hyperparathyroidism

CONTEXT

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 role of parathyroidectomy (PTX) on DBP and cytokines is not clear.

OBJECTIVE

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 in 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 BMI-matched healthy subjects were included as controls (n=70).

RESULTS

Prior to PTX, patients had lower serum DBP (37.5±6.0 vs 41.5±6.1mg/dL, p<0.001) and total 25OHD (30.1±9.5 vs 33.3±7.9ng/mL, P<0.05), but similar free 25OHD when compared to controls. Serum IL-6, C-reactive protein (CRP), and MCP-1 were higher in PHPT patients (p<0.05), whereas interleukin-10 (IL-10) was similar to controls. PTX increased total and free 25OHD and DBP (p<0.001), and decreased serum IL-6 and MCP-1 (p<0.05), but not CRP and IL-10. Multiple regression analysis indicated that the preoperative PTH explained a significant portion of the variance of IL-6 and MCP-1 (p<0.05).

CONCLUSIONS

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 effect of IL-6 and MCP-1 on DBP, vitamin D metabolites and the role on clinical outcomes in patients with PHPT is an area requiring further study.

Histologic Characterization of Tumor-Adjacent Mammary Adipose Tissue in Normal-Weight and Overweight/Obese Patients with Triple-Negative Breast Cancer

Background: Obesity is a risk factor of several types of cancer, including breast cancer. In this study, we aimed to histologically characterize the adipose tissue of the tumor microenvironment (TME) of triple-negative breast cancer (TNBC) in overweight/obese versus normal-weight patients. Methods: TNBC tissue sections from normal-weight (BMI<25) and overweight/obese patients (BMI≥25) were stained with antibodies against CD68, CD163, CD31, CD34, and vimentin. At the invasive tumor front, positive cells were counted in tumor adjacent adipose tissue (AT) and within cancer tissue (CT). Further, the size of the tumor-adjacent and distant mammary adipocytes was determined in perilipin stained sections. Expression of ANGPTL4, CD36 and FABP4, proteins involved in fatty acid metabolism, was analyzed in marginal tumor cells using an immune reactive score. Results: Overweight/obese TNBC patients had significantly larger adipocytes, higher numbers of CD163+ macrophages (BMI<25: 2.80 vs. BMI≥25: 10.45; p = 0.011) and lower numbers of CD31+ (BMI<25: 4.20 vs. BMI≥25: 2.40; p = 0.018) and CD34+ (BMI<25: 14.60 vs. BMI≥25: 5.20; p = 0.045) cells as markers of angiogenesis in the AT as well as a higher frequency of cancer-associated-fibroblast-like cells in the AT and CT (BMI<25: 7.60 vs. BMI≥25: 25.39 in total; p = 0.001). Moreover, expression of CD36 (BMI<25: 2.15 vs. BMI≥25: 2.60; p = 0.041) and ANGPTL4 (BMI<25: 6.00 vs. BMI≥25: 9.80; p = 0.026) was elevated in the TNBC cells of overweight/obese patients. Conclusions: Our data suggest BMI-related changes in the TME of overweight/obese TNBC patients, including hypertrophied adipocytes, reduced vascularization, more M2-like macrophages and CAF-like cells, and an increase in the expression of fatty acid metabolizing proteins in marginal tumor cells, all contributing to a more tumor-promoting, immunosuppressive environment.

Engineering mtDNA Deletions by Reconstituting End-Joining in Human Mitochondria

Recent breakthroughs in the genetic manipulation of mitochondrial DNA (mtDNA) have enabled the precise introduction of base substitutions and the effective removal of genomes carrying harmful mutations. However, the reconstitution of mtDNA deletions responsible for severe mitochondrial myopathies and age-related diseases has not yet been achieved in human cells. Here, we developed a method to engineer specific mtDNA deletions in human cells by co-expressing end-joining (EJ) machinery and targeted endonucleases. As a proof-of-concept, we used mito-EJ and mito-ScaI to generate a panel of clonal cell lines harboring a ∼3.5 kb mtDNA deletion with the full spectrum of heteroplasmy. Investigating these isogenic cells revealed a critical threshold of ∼75% deleted genomes, beyond which cells exhibited depletion of OXPHOS proteins, severe metabolic disruption, and impaired growth in galactose-containing media. Single-cell multiomic analysis revealed two distinct patterns of nuclear gene deregulation in response to mtDNA deletion accumulation; one triggered at the deletion threshold and another progressively responding to increasing heteroplasmy. In summary, the co-expression of mito-EJ and programable nucleases provides a powerful tool to model disease-associated mtDNA deletions in different cell types. Establishing a panel of cell lines with a large-scale deletion at varying levels of heteroplasmy is a valuable resource for understanding the impact of mtDNA deletions on diseases and guiding the development of potential therapeutic strategies.

Highlights

Combining prokaryotic end-joining with targeted endonucleases generates specific mtDNA deletions in human cellsEngineering a panel of cell lines with a large-scale deletion that spans the full spectrum of heteroplasmy75% heteroplasmy is the threshold that triggers mitochondrial and cellular dysfunctionTwo distinct nuclear transcriptional programs in response to mtDNA deletions: threshold-triggered and heteroplasmy-sensing.

Molecular mechanisms of mitochondrial dynamics

Mitochondria not only synthesize energy required for cellular functions but are also involved in numerous cellular pathways including apoptosis, calcium homoeostasis, inflammation and immunity. Mitochondria are dynamic organelles that undergo cycles of fission and fusion, and these transitions between fragmented and hyperfused networks ensure mitochondrial function, enabling adaptations to metabolic changes or cellular stress. Defects in mitochondrial morphology have been associated with numerous diseases, highlighting the importance of elucidating the molecular mechanisms regulating mitochondrial morphology. Here, we discuss recent structural insights into the assembly and mechanism of action of the core mitochondrial dynamics proteins, such as the dynamin-related protein 1 (DRP1) that controls division, and the mitofusins (MFN1 and MFN2) and optic atrophy 1 (OPA1) driving membrane fusion. Furthermore, we provide an updated view of the complex interplay between different proteins, lipids and organelles during the processes of mitochondrial membrane fusion and fission. Overall, we aim to present a valuable framework reflecting current perspectives on how mitochondrial membrane remodelling is regulated.

The role of exercise-related FNDC5/irisin in depression

The complexity of depression presents a significant challenge to traditional treatment methods, such as medication and psychotherapy. Recent studies have shown that exercise can effectively reduce depressive symptoms, offering a new alternative for treating depression. However, some depressed patients are unable to engage in regular physical activity due to age, physical limitations, and other factors. Therefore, pharmacological agents that mimic the effects of exercise become a potential treatment option. A newly discovered myokine, irisin, which is produced during exercise via cleavage of its precursor protein fibronectin type III domain-containing protein 5 (FNDC5), plays a key role in regulating energy metabolism, promoting adipose tissue browning, and improving insulin resistance. Importantly, FNDC5 can promote neural stem cell differentiation, enhance neuroplasticity, and improve mood and cognitive function. This review systematically reviews the mechanisms of action of exercise in the treatment of depression, outlines the physiology of exercise-related irisin, explores possible mechanisms of irisin's antidepressant effects. The aim of this review is to encourage future research and clinical applications of irisin in the prevention and treatment of depression.

Interplay of co-cultured chimeric adipose and gingival tissues exacerbates inflammatory dysfunction relevant to periodontal and metabolic conditions

Adipose tissue dysfunction is a key feature of metabolic syndrome, which increases the risk of periodontitis, an inflammatory disease induced by bacteria that affects the gingiva and other components of periodontal tissue. Recent studies indicate that molecules from inflamed periodontal tissue contribute to adipose tissue dysfunction. However, the cellular mechanisms and interactions between adipose tissue and gingiva driving the progression of metabolic and periodontal conditions remain unclear. To address this, we developed a chimeric (mouse/human) co-culture tissue model (which identifies the origins of species-specific cytokines) to investigate these interactions. Using tissue-specific functional cells and immunocytes, we constructed equivalents of adipose tissue (ATE) and gingiva (GTE), co-cultivating them under inflammatory conditions induced by bacterial endotoxin, lipopolysaccharide (LPS). Our findings showed that exposure to LPS resulted in a notable reduction in lipid accumulation, GLUT4 expression, and adiponectin secretion in ATE, along with increased macrophage colonies forming around lipid droplets, as well as elevated levels of triglyceride, leptin, and IL-6. In GTE, LPS triggered significant inflammatory responses, characterized by increased macrophage accumulation, elevated COX-2 expression, and heightened secretion of inflammatory cytokines. LPS also reduced epithelial thickness and the expression of keratin 19 and collagen IV, indicating impaired barrier function and gingival integrity. Co-culturing ATE with GTE exacerbated these LPS-induced harmful effects in both tissues. In conclusion, our findings suggest that interplay between gingiva and adipose tissue can intensify the inflammatory and dysfunctional changes caused by LPS. This co-culture tissue model offers a valuable tool for future studies on periodontitis and metabolic syndrome.

Irisin suppresses PDGF-BB-induced proliferation of vascular smooth muscle cells in vitro by activating AMPK/mTOR-mediated autophagy

Restenosis is a pivotal factor that restricts the efficacy of coronary artery bypass grafting. Inhibition of vascular smooth muscle cells (VSMCs) proliferation can improve intimal hyperplasia and lumen stenosis. Irisin, a polypeptide secreted by muscle cells, has been demonstrated to have a protective role in various cardiovascular diseases. However, the effect and mechanism of irisin on VSMCs proliferation and phenotype switching remain unclear. Cell proliferation ability was assessed using the methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay and 5-ethynyl-2'-deoxyuridine (EdU) incorporation. Cell cycle analysis was performed using flow cytometry, while expression levels of contractile and synthesis-related proteins were determined through RT-qPCR and Western blot. The VSMCs were infected with an adenovirus carrying GFP-LC3, and the proportion of cells showing positive expression was assessed. Additionally, the formation of autophagic lysosomes in cells was observed through transmission electron microscopy. In this study, we have demonstrated the inhibitory effects of irisin on the proliferation and phenotypic transition of platelet-derived growth factor-BB (PDGF-BB)-induced VSMCs. More importantly, we have discovered that irisin can activate the AMP-activated protein kinase/mammalian target of rapamycin (AMPK/mTOR) signaling pathway to mediate autophagy in PDGF-BB-induced VSMCs. The inhibitory effect of irisin on PDGF-BB-induced VSMCs proliferation was significantly attenuated by the AMPK inhibitor, Compound C. Conversely the mTOR inhibitor, rapamycin further enhanced the inhibitory effect of irisin on PDGF-BB induced VSMCs proliferation. In conclusion, our findings suggest that irisin effectively suppresses the aberrant proliferation of VSMCs following PDGF-BB stimulation by modulating autophagy levels through the AMPK/mTOR signaling pathway.

Myocardial ischemia-reperfusion injury: The balance mechanism between mitophagy and NLRP3 inflammasome

Myocardial ischemia-reperfusion injury (MIRI) is an injury to cardiomyocytes due to restoration of blood flow after myocardial infarction (MI). It has recently gained much attention in clinical research with special emphasis on the roles of mitochondrial autophagy and inflammation. A mild inflammatory response promotes recovery of post-ischemic cardiomyocyte function and vascular regeneration, but a severe inflammatory response can cause irreversible and substantial cellular damage. Similarly, moderate mitochondrial autophagy can help inhibit excessive inflammation and protect cardiomyocytes. However, MIRI is aggravated when mitochondrial function is disrupted, such as inadequate clearance of damaged mitochondria or excessive activation of mitophagy. How to moderately control mitochondrial autophagy while promoting its balance with nucleotide-binding oligomerization structural domain receptor protein 3 (NLRP3) inflammasome activation is critical. In this paper, we reviewed the molecular mechanisms of mitochondrial autophagy and NLRP3 inflammasome, described the interaction between NLRP3 inflammasome and mitochondrial autophagy, and the effects of different signaling pathways and molecular proteins on MIRI, to provide a reference for future research.

TRPV4 modulation affects mitochondrial parameters in adipocytes and its inhibition upregulates lipid accumulation

Enhanced lipid-droplet formation by adipocytes is a complex process and relevant for obesity. Using knock-out animals, involvement of TRPV4, a thermosensitive ion channel in the obesity has been proposed. However, exact role/s of TRPV4 in adipogenesis and obesity remain unclear and contradictory. Here we used in vitro culture of 3T3L-1 preadipocytes and primary murine-mesenchymal stem cells as model systems, and a series of live-cell-imaging to analyse the direct involvement of TRPV4 exclusively at the adipocytes that are free from other complex signalling as expected in in-vivo condition. Functional TRPV4 is endogenously expressed in pre- and in mature-adipocytes. Pharmacological inhibition of TRPV4 enhances differentiation of preadipocytes to mature adipocytes, increases expression of adipogenic and lipogenic genes, enhances cholesterol, promotes bigger lipid-droplet formation and reduces the lipid droplet temperature. On the other hand, TRPV4 activation enhanced the browning of adipocytes with increased UCP-1 levels. TRPV4 regulates mitochondrial-temperature, Ca2+-load, ATP, superoxides, cardiolipin, membrane potential (ΔΨm), and lipid-mitochondrial contact sites. TRPV4 also regulates the extent of actin fibres, affecting the cells mechanosensing ability. These findings link TRPV4-mediated mitochondrial changes in the context of lipid-droplet formation involved in adipogenesis and confirm the direct involvement of TRPV4 in adipogenesis. These findings may have broad implication in treating adipogenesis and obesity in future.

A metabolic dysfunction-associated steatotic liver acinus biomimetic induces pancreatic islet dysfunction in a coupled microphysiology system

Preclinical and clinical studies suggest that lipid-induced hepatic insulin resistance is a primary defect that predisposes to dysfunction in islets, implicating a perturbed liver-pancreas axis underlying the comorbidity of T2DM and MASLD. To investigate this hypothesis, we developed a human biomimetic microphysiological system (MPS) coupling our vascularized liver acinus MPS (vLAMPS) with pancreatic islet MPS (PANIS) enabling MASLD progression and islet dysfunction to be assessed. The modular design of this system (vLAMPS-PANIS) allows intra-organ and inter-organ dysregulation to be deconvoluted. When compared to normal fasting (NF) conditions, under early metabolic syndrome (EMS) conditions, the standalone vLAMPS exhibited characteristics of early stage MASLD, while no significant differences were observed in the standalone PANIS. In contrast, with EMS, the coupled vLAMPS-PANIS exhibited a perturbed islet-specific secretome and a significantly dysregulated glucose stimulated insulin secretion response implicating direct signaling from the dysregulated liver acinus to the islets. Correlations between several pairs of a vLAMPS-derived and a PANIS-derived factors were significantly altered under EMS, as compared to NF conditions, mechanistically connecting MASLD and T2DM associated hepatic-factors with islet-derived GLP-1 synthesis and regulation. Since vLAMPS-PANIS is compatible with patient-specific iPSCs, this platform represents an important step towards addressing patient heterogeneity, identifying disease mechanisms, and advancing precision medicine.

Myeloid cannabinoid CB1 receptor deletion confers atheroprotection in male mice by reducing macrophage proliferation in a sex-dependent manner

AIMS

Although the cannabinoid CB1 receptor has been implicated in atherosclerosis, its cell-specific effects in this disease are not well understood. To address this, we generated a transgenic mouse model to study the role of myeloid CB1 signalling in atherosclerosis.

METHODS AND RESULTS

Here, we report that male mice with myeloid-specific Cnr1 deficiency on atherogenic background developed smaller lesions and necrotic cores than controls, while only minor genotype differences were observed in females. Male Cnr1-deficient mice showed reduced arterial monocyte recruitment and macrophage proliferation with less inflammatory phenotype. The sex-specific differences in proliferation were dependent on oestrogen receptor (ER)α-oestradiol signalling. Kinase activity profiling identified a CB1-dependent regulation of p53 and cyclin-dependent kinases. Transcriptomic profiling further revealed chromatin modifications, mRNA processing, and mitochondrial respiration among the key processes affected by CB1 signalling, which was supported by metabolic flux assays. Chronic administration of the peripherally restricted CB1 antagonist JD5037 inhibited plaque progression and macrophage proliferation, but only in male mice. Finally, CNR1 expression was detectable in human carotid endarterectomy plaques and inversely correlated with proliferation, oxidative metabolism, and inflammatory markers, suggesting a possible implication of CB1-dependent regulation in human pathophysiology.

CONCLUSION

Impaired macrophage CB1 signalling is atheroprotective by limiting their arterial recruitment, proliferation, and inflammatory reprogramming in male mice. The importance of macrophage CB1 signalling appears to be sex-dependent.

Positive Effects of Aerobic-Resistance Exercise and an Ad Libitum High-Protein, Low-Glycemic Index Diet on Irisin, Omentin, and Dyslipidemia in Men with Abdominal Obesity: A Randomized Controlled Trial

OBJECTIVES

The aim of this research was to evaluate changes in body composition, adipokine levels, and dyslipidemia parameters in males with abdominal obesity following two distinct interventions: exercise alone and exercise combined with an ad libitum diet.

METHODS

This study included 44 males with abdominal obesity (mean age 34.7 ± 5.5 years, waist circumference [WC] 110.3 ± 8.5, BMI 32.0 ± 3.9), who were randomly assigned to three groups: an experimental group engaging in aerobic-resistance exercise (II, n = 16), an experimental group engaging in aerobic-resistance exercise combined with an ad libitum high-protein, low-glycemic index carbohydrate diet (III, n = 16), both interventions lasting 6 weeks, and a control group without interventions (I, n = 12). Body composition metrics (body mass index [BMI], waist circumference [WC], body fat [BF], abdominal fat [ABD]) and fat-free mass [FFM], along with biochemical blood analyses (irisin [IR], omentin [OMEN], glucose [GLU], insulin [INS], LDL- and HDL-cholesterol), were measured at baseline and after the 6-week intervention. The effects of the interventions on the analyzed variables across groups were assessed using mixed ANOVA tests with post-hoc comparisons. Effect size (ES) was also calculated using partial eta squared (ηp2).

RESULTS

The intervention in group III resulted in a significant decrease in IR (p < 0.01, ηp2 = 0.03) by 41% and LDL-C (p < 0.01, ηp2 = 0.02) by 14%. These effects were associated with a reduction in BF (p < 0.01, ηp2 = 0.02) by 14%, ABD (p < 0.01, ηp2 = 0.03) by 31%, and WC (p < 0.01, ηp2 = 0.01) by 3%. In group II, decreases after 6 weeks of intervention were noted only in WC (p = 0.02, ηp2 = 0.01) by 1% and in INS (p < 0.01, ηp2 = 0.04) by 47%. No differences were found between groups. The use of low-glycemic index carbohydrates (p < 0.01, ηp2 = 0.06) and increased protein intake (p < 0.01, ηp2 = 0.30) led to changes in the fiber-to-energy value of the diet ratio (p < 0.01, ηp2 = 0.18) and a reduction in dietary energy value (p < 0.01, ηp2 = 0.13) by 23%, resulting in a greater energy deficit than in the II group.

CONCLUSIONS

These findings highlight the effect of combining dietary and exercise interventions to achieve significant changes in body composition and metabolic parameters, even over a short period of intervention.

A novel genetic mouse model of osteoporosis with double heterozygosity of Irx3 and Irx5 characterizes sex-dependent phenotypes in bone homeostasis

Iroquois homeobox gene 3 (Irx3) and Irx5 encode transcription factors that play crucial roles in limb development and bone formation. Previous studies using knockout mice have revealed a role of Irx3 and Irx5 in osteogenesis in young adult mice. However, whether these genes are also essential for bone homeostasis in adulthood and contribute to bone diseases remain poorly understood. Osteoporosis is a disease characterized by lower bone mineral density and disrupted bone microarchitecture, typically occurs in postmenopausal women. Here, we demonstrate that Irx3/5dHet mice with a half-reduction of Irx3 and Irx5 dosage serve as a novel model of osteoporosis. By micro-computed tomography, we found that Irx3/5dHet mice exhibited sex-dependent bone loss patterns. While male Irx3/5dHet mice progressively lost trabecular microstructures with aging, female mutants exhibited lower bone mineral density (BMD) and bone volume fraction (BV/TV) at early adulthood (9-15 weeks old) but without further loss later at 1 year of age. Bone marrow adipocytes are known to be elevated at the expenses of lower osteogenesis in osteoporotic bone marrow. Surprisingly, we found sex-dependent changes in adipogenesis at the age of skeletal maturity that bone marrow adipocytes were reduced in female Irx3/5dHet mice along with deteriorated osteogenesis, while male mice exhibited elevated adipogenesis. In summary, we reported a novel genetic model for osteoporosis-like phenotypes, highlighting sex-dependent bone mineral density and bone marrow adipocyte characteristics.

Luteolin alleviates muscle atrophy, mitochondrial dysfunction and abnormal FNDC5 expression in high fat diet-induced obese rats and palmitic acid-treated C2C12 myotubes

Obesity is associated with a series of skeletal muscle impairments and dysfunctions, which are characterized by metabolic disturbances and muscle atrophy. Luteolin is a phenolic phytochemical with broad pharmacological activities. The present study aimed to evaluate the protective effects of Luteolin on muscle function and explore the potential mechanisms in high-fat diet (HFD)-induced obese rats and palmitic acid (PA)-treated C2C12 myotubes. Male Sprague-Dawley (SD) rats were fed with a control diet or HFD and orally administrated 0.5% sodium carboxymethyl cellulose (vehicle) or Luteolin (25, 50, and 100 mg/kg, respectively) for 12 weeks. The results showed that Luteolin ameliorated HFD-induced body weight gain, glucose intolerance and hyperlipidemia. Luteolin also alleviated muscle atrophy, decreased ectopic lipid deposition and prompted muscle-fiber-type conversion in the skeletal muscle. Meanwhile, we observed an evident improvement in mitochondrial quality control and respiratory capacity, accompanied by reduced oxidative stress. Mechanistic studies indicated that AMPK/SIRT1/PGC-1α signaling pathway plays a key role in the protective effects of Luteolin on skeletal muscle in the obese states, which was further verified by using specific inhibitors of AMPK and SIRT1. Moreover, the mRNA expression levels of markers in brown adipocyte formation were significantly up-regulated post Luteolin supplementation in different adipose depots. Taken together, these results revealed that Luteolin supplementation might be a promising strategy to prevent obesity-induced loss of mass and biological dysfunctions of skeletal muscle.

Aerobic Exercise Prevents High-Fat-Diet-Induced Adipose Tissue Dysfunction in Male Mice

BACKGROUND/OBJECTIVES

This study aimed to assess the effect of aerobic exercise on capillary density and vascular smooth muscle cell (VSMC) phenotype in the visceral and subcutaneous adipose tissue of high-fat-diet (HFD) mice in order to understand the mechanisms underlying improvements in insulin resistance (IR) and chronic inflammation in adipose tissue (AT).

METHODS

Male C57BL/6J mice were divided into HFD and normal diet groups for 12 weeks and then further split into sedentary and aerobic exercise subgroups for an additional 8 weeks. Various parameters including body weight, fat weight, blood glucose, lipid profile, insulin levels, glucose tolerance, and inflammatory cytokines were evaluated.

RESULTS

Aerobic exercise reduced HFD-induced weight gain, IR, and improved lipid profiles. HFD had a minimal effect on inflammatory cytokines except in visceral adipose tissue (VAT). IR was associated with capillary density in subcutaneous adipose tissue (SAT) and VSMC phenotype in VAT. Aerobic exercise promoted anti-inflammatory responses in VAT, correlating with VSMC phenotype in this tissue.

CONCLUSIONS

Aerobic exercise can alleviate HFD-induced IR and inflammation through the modulation of VSMC phenotype in AT.

Rewriting cellular fate: epigenetic interventions in obesity and cellular programming

External constraints, such as development, disease, and environment, can induce changes in epigenomic patterns that may profoundly impact the health trajectory of fetuses and neonates into adulthood, influencing conditions like obesity. Epigenetic modifications encompass processes including DNA methylation, covalent histone modifications, and RNA-mediated regulation. Beyond forward cellular differentiation (cell programming), terminally differentiated cells are reverted to a pluripotent or even totipotent state, that is, cellular reprogramming. Epigenetic modulators facilitate or erase histone and DNA modifications both in vivo and in vitro during programming and reprogramming. Noticeably, obesity is a complex metabolic disorder driven by both genetic and environmental factors. Increasing evidence suggests that epigenetic modifications play a critical role in the regulation of gene expression involved in adipogenesis, energy homeostasis, and metabolic pathways. Hence, we discuss the mechanisms by which epigenetic interventions influence obesity, focusing on DNA methylation, histone modifications, and non-coding RNAs. We also analyze the methodologies that have been pivotal in uncovering these epigenetic regulations, i.e., Large-scale screening has been instrumental in identifying genes and pathways susceptible to epigenetic control, particularly in the context of adipogenesis and metabolic homeostasis; Single-cell RNA sequencing (scRNA-seq) provides a high-resolution view of gene expression patterns at the individual cell level, revealing the heterogeneity and dynamics of epigenetic regulation during cellular differentiation and reprogramming; Chromatin immunoprecipitation (ChIP) assays, focused on candidate genes, have been crucial for characterizing histone modifications and transcription factor binding at specific genomic loci, thereby elucidating the epigenetic mechanisms that govern cellular programming; Somatic cell nuclear transfer (SCNT) and cell fusion techniques have been employed to study the epigenetic reprogramming accompanying cloning and the generation of hybrid cells with pluripotent characteristics, etc. These approaches have been instrumental in identifying specific epigenetic marks and pathways implicated in obesity, providing a foundation for developing targeted therapeutic interventions. Understanding the dynamic interplay between epigenetic regulation and cellular programming is crucial for advancing mechanism and clinical management of obesity.

Recent Advances of Exosomes Derived from Skeletal Muscle and Crosstalk with Other Tissues

Skeletal muscle plays a crucial role in movement, metabolism, and energy homeostasis. As the most metabolically active endocrine organ in the body, it has recently attracted widespread attention. Skeletal muscle possesses the ability to release adipocytokines, bioactive peptides, small molecular metabolites, nucleotides, and other myogenic cell factors; some of which have been shown to be encapsulated within small vesicles, particularly exosomes. These skeletal muscle exosomes (SKM-Exos) are released into the bloodstream and subsequently interact with receptor cell membranes to modulate the physiological and pathological characteristics of various tissues. Therefore, SKM-Exos may facilitate diverse interactions between skeletal muscle and other tissues while also serving as biomarkers that reflect the physiological and pathological states of muscle function. This review delves into the pivotal role and intricate molecular mechanisms of SKM-Exos and its derived miRNAs in the maturation and rejuvenation of skeletal muscle, along with their intercellular signaling dynamics and physiological significance in interfacing with other tissues.

Exploring lipodystrophy gene expression in adipocytes: unveiling insights into the pathogenesis of insulin resistance, type 2 diabetes, and clustering diseases (metabolic syndrome) in Asian Indians

Background

Studying the molecular mechanisms of lipodystrophy can provide valuable insights into the pathophysiology of insulin resistance (IR), type 2 diabetes (T2D), and other clustering diseases [metabolic syndrome (MetS)] and its underlying adipocentric disease (MetS disease).

Methods

A high-confidence lipodystrophy gene panel comprising 50 genes was created, and their expressions were measured in the visceral and subcutaneous (both peripheral and abdominal) adipose depots of MetS and non-MetS individuals at a tertiary care medical facility.

Results

Most lipodystrophy genes showed significant downregulation in MetS individuals compared to non-MetS individuals in both subcutaneous and visceral depots. In the abdominal compartment, all the genes showed relatively higher expression in visceral depot as compared to their subcutaneous counterpart, and this difference narrowed with increasing severity of MetS. Their expression level shows an inverse correlation with T2D, MetS, and HOMA-IR and with other T2D-related intermediate traits. Results also demonstrated that individualization of MetS patients could be done based on adipose tissue expression of just 12 genes.

Conclusion

Adipose tissue expression of lipodystrophy genes shows an association with MetS and its intermediate phenotypic traits. Mutations of these genes are known to cause congenital lipodystrophy syndromes, whereas their altered expression in adipose tissue contributes to the pathogenesis of IR, T2D, and MetS.

Mitochondrial Function and Dysfunction in White Adipocytes and Therapeutic Implications

For a long time, white adipocytes were thought to function as lipid storages due to the sizeable unilocular lipid droplet that occupies most of their space. However, recent discoveries have highlighted the critical role of white adipocytes in maintaining energy homeostasis and contributing to obesity and related metabolic diseases. These physiological and pathological functions depend heavily on the mitochondria that reside in white adipocytes. This article aims to provide an up-to-date overview of the recent research on the function and dysfunction of white adipocyte mitochondria. After briefly summarizing the fundamental aspects of mitochondrial biology, the article describes the protective role of functional mitochondria in white adipocyte and white adipose tissue health and various roles of dysfunctional mitochondria in unhealthy white adipocytes and obesity. Finally, the article emphasizes the importance of enhancing mitochondrial quantity and quality as a therapeutic avenue to correct mitochondrial dysfunction, promote white adipocyte browning, and ultimately improve obesity and its associated metabolic diseases. © 2024 American Physiological Society. Compr Physiol 14:5581-5640, 2024.

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.

Transport of Neutral Amino Acids in the Jejunum of Pigs with Special Consideration of L-Methionine

Background: Methionine (Met) is a popular nutritional supplement in humans and animals. It is routinely supplemented to pigs as L-Met, DL-Met, or DL-2-hydroxy-4-(methylthio) butanoic acid (DL-HMTBA). Methods: We investigated the effect of these Met supplements on jejunal amino acid (AA) transport in male castrated Piétrain × Danbred pigs, also including a non-supplemented group. The mucosal-to-serosal flux of ten [14C]-labeled AAs (L-glutamine, glycine, L-leucine, L-lysine, L-Met, L-serine, L-threonine, L-tryptophan, L-tyrosine and L-valine) was investigated at two concentrations (50 µM and 5 mM). Inhibition of apical uptake by mucosal L-Met was also measured for these AAs. The intestinal expression of apical AA transporters, angiotensin-converting enzyme II and inflammation-related genes were compared with those of a previous study. Results: Except for tryptophan and lysine at 5 mM, all AA fluxes were Na+-dependent (p ≤ 0.05), and the uptake of most AAs, except glycine and lysine, was inhibited by L-Met (p < 0.001). A correlation network existed between Na+-dependent fluxes of most AAs (except tryptophan and partly glycine). We observed the upregulation of B0AT1 (SLC6A19) (p < 0.001), the downregulation of ATB0,+ (SLC6A14) (p < 0.001) and a lower expression of CASP1, IL1β, IL8, TGFβ and TNFα in the present vs. the previous study (p < 0.001). Conclusions: The correlating AAs likely share the same Na+-dependent transporter(s). A varying effect of the Met supplement type on AA transport in the two studies might be related to a different level of supplementation or a different inflammatory status of the small intestine.

TOMM40-APOE chimera linking Alzheimer's highest risk genes: a new pathway for mitochondria regulation and APOE4 pathogenesis

The patho-mechanism of apolipoprotein variant, APOE4, the strongest genetic risk for late-onset Alzheimer's disease (AD) and longevity, remains unclear. APOE's neighboring gene, TOMM40 (mitochondria protein transport channel), is associated with brain trauma outcome and aging-related cognitive decline, however its role in AD APOE4-independently is controversial. We report that TOMM40 is prone to transcription readthrough into APOE that can generate spliced TOMM40-APOE mRNA chimera (termed T9A2) detected in human neurons and other cells and tissues. T9A2 translation tethers APOE (normal APOE3 or APOE4) to near-full-length TOM40 that is targeted to mitochondria. Importantly, T9A2-APOE3 boosts mitochondrial bioenergetic capacity and decreases oxidative stress significantly more than T9A2-APOE4 and APOE3, and lacking in APOE4. We describe detailed interactomes of these actors that may inform about the activities and roles in pathogenesis. T9A2 uncovers a new candidate pathway for mitochondria regulation and oxidative stress-protection that are impaired in APOE4 genotypes and could initiate neurodegeneration.

A review on drug repurposing applicable to obesity

Obesity is a major public health concern and burden on individuals and healthcare systems. Due to the challenges and limitations of lifestyle adjustments, it is advisable to consider pharmacological treatment for people affected by obesity. However, the side effects and limited efficacy of available drugs make the obesity drug market far from sufficient. Drug repurposing involves identifying new applications for existing drugs and offers some advantages over traditional drug development approaches including lower costs and shorter development timelines. This review aims to provide an overview of drug repurposing for anti-obesity medications, including the rationale for repurposing, the challenges and approaches, and the potential drugs that are being investigated for repurposing. Through advanced computational techniques, researchers can unlock the potential of repurposed drugs to tackle the global obesity epidemic. Further research, clinical trials, and collaborative efforts are essential to fully explore and leverage the potential of drug repurposing in the fight against obesity.

Obesity and leptin in breast cancer angiogenesis

At the time of breast cancer diagnosis, most patients meet the diagnostic criteria to be classified as obese or overweight. This can significantly impact patient outcome: breast cancer patients with obesity (body mass index > 30) have a poorer prognosis compared to patients with a lean BMI. Obesity is associated with hyperleptinemia, and leptin is a well-established driver of metastasis in breast cancer. However, the effect of hyperleptinemia on angiogenesis in breast cancer is less well-known. Angiogenesis is an important process in breast cancer because it is essential for tumor growth beyond 1mm3 in size as well as cancer cell circulation and metastasis. This review investigates the role of leptin in regulating angiogenesis, specifically within the context of breast cancer and the associated tumor microenvironment in obese patients.

Effects and mechanisms of supramaximal high-intensity interval training on extrapulmonary manifestations in people with and without chronic obstructive pulmonary disease (COPD-HIIT): study protocol for a multi-centre, randomized controlled trial

BACKGROUND

Beyond being a pulmonary disease, chronic obstructive pulmonary disease (COPD) presents with extrapulmonary manifestations including reduced cognitive, cardiovascular, and muscle function. While exercise training is the cornerstone in the non-pharmacological treatment of COPD, there is a need for new exercise training methods due to suboptimal adaptations when following traditional exercise guidelines, often applying moderate-intensity continuous training (MICT). In people with COPD, short-duration high-intensity interval training (HIIT) holds the potential to induce a more optimal stimulus for training adaptations while circumventing the ventilatory burden often associated with MICT in people with COPD. We aim to determine the effects of supramaximal HIIT and MICT on extrapulmonary manifestations in people with COPD compared to matched healthy controls.

METHODS

COPD-HIIT is a prospective, multi-centre, randomized, controlled trial with blinded assessors and data analysts, employing a parallel-group designed trial. In phase 1, we will investigate the effects and mechanisms of a 12-week intervention of supramaximal HIIT compared to MICT in people with COPD (n = 92) and matched healthy controls (n = 70). Participants will perform watt-based cycling two to three times weekly. In phase 2, we will determine how exercise training and inflammation impact the trajectories of neurodegeneration, in people with COPD, over 24 months. In addition to the 92 participants with COPD performing HIIT or MICT, a usual care group (n = 46) is included in phase 2. In both phases, the primary outcomes are a change from baseline in cognitive function, cardiorespiratory fitness, and muscle power. Key secondary outcomes include change from baseline exercise tolerance, brain structure, and function measured by MRI, neuroinflammation measured by PET/CT, systemic inflammation, and intramuscular adaptations. Feasibility of the interventions will be comprehensively investigated.

DISCUSSION

The COPD-HIIT trial will determine the effects of supramaximal HIIT compared to MICT in people with COPD and healthy controls. We will provide evidence for a novel exercise modality that might overcome the barriers associated with MICT in people with COPD. We will also shed light on the impact of exercise at different intensities to reduce neurodegeneration. The goal of the COPD-HIIT trial is to improve the treatment of extrapulmonary manifestations of the disease.

TRIAL REGISTRATION

Clinicaltrials.gov: NCT06068322. Prospectively registered on 2023-09-28.

Inflammatory Trajectory of Type 2 Diabetes: Novel Opportunities for Early and Late Treatment

Low-grade inflammation (LGI) represents a key driver of type 2 diabetes (T2D) and its associated cardiovascular diseases (CVDs). Indeed, inflammatory markers such as hs-CRP and IL-6 predict the development of T2D and its complications, suggesting that LGI already increases before T2D diagnosis and remains elevated even after treatment. Overnutrition, unhealthy diets, physical inactivity, obesity, and aging are all recognized triggers of LGI, promoting insulin resistance and sustaining the pathogenesis of T2D. Once developed, and even before frank appearance, people with T2D undergo a pathological metabolic remodeling, with an alteration of multiple CVD risk factors, i.e., glycemia, lipids, blood pressure, and renal function. In turn, such variables foster a range of inflammatory pathways and mechanisms, e.g., immune cell stimulation, the accrual of senescent cells, long-lasting epigenetic changes, and trained immunity, which are held to chronically fuel LGI at the systemic and tissue levels. Targeting of CVD risk factors partially ameliorates LGI. However, some long-lasting inflammatory pathways are unaffected by common therapies, and LGI burden is still increased in many T2D patients, a phenomenon possibly underlying the residual inflammatory risk (i.e., having hs-CRP > 2 mg/dL despite optimal LDL cholesterol control). On the other hand, selected disease-modifying drugs, e.g., GLP-1RA, seem to also act on the pathogenesis of T2D, curbing the inflammatory trajectory of the disease and possibly preventing it if introduced early. In addition, selected trials demonstrated the potential of canonical anti-inflammatory therapies in reducing the rate of CVDs in patients with this condition or at high risk for it, many of whom had T2D. Since colchicine, an inhibitor of immune cell activation, is now approved for the prevention of CVDs, it might be worth exploring a possible therapeutic paradigm to identify subjects with T2D and an increased LGI burden to treat them with this drug. Upcoming studies will reveal whether disease-modifying drugs reverse early T2D by suppressing sources of LGI and whether colchicine has a broad benefit in people with this condition.

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.

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.

Baicalin suppresses macrophage JNK-mediated adipose tissue inflammation to mitigate insulin resistance in obesity

ETHNOPHARMACOLOGICAL RELEVANCE

Radix scutellariae (the root of Scutellaria baicalensis Georgi) is a traditional Chinese medicine (TCM) used to treat a wide range of inflammation-related diseases, such as obesity, diabetes, diabetic kidney disease, and COVID-19-associated inflammatory states in the lung and kidney. Baicalin is the major anti-inflammatory component of Radix scutellariae and has shown the potential to inhibit inflammation in metabolic disorders. In this study, we explored the ability and underlying mechanisms of baicalin to modulate the macrophage to mitigate insulin resistance in obesity.

MATERIALS AND METHODS

Obese mice were administered baicalin (50 mg/kg/day) intraperitoneally for 3 weeks. RAW264.7 and BMDM cells were stimulated with LPS and treated with baicalin for 24 h, while 3T3-L1 and primary white adipocytes were treated with the supernatants from baicalin-treated RAW264.7 cells for 24 h.

RESULTS

The results showed that baicalin significantly improved glucose and insulin tolerance as well as decreased fat and adipose tissue macrophage levels in obese mice. Besides, baicalin significantly reduced serum and adipose tissue IL-1β, TNF-α and IL-6 levels in obese mice, as well as suppressed LPS-induced IL-1β, TNF-α and IL-6 expression and release in macrophages. Furthermore, treatment with the supernatant from baicalin-treated RAW264.7 cells increased the levels of PGC-1α, SIRT1, p-IRS-1 and p-AKT in adipocytes. Moreover, baicalin treatment dramatically downregulated macrophage p-p38, p-JNK, and Ac-p65Lys310 levels while increasing SIRT1 both in vivo and in vitro. Importantly, JNK inhibitor SP600125 blocked most of the effects of baicalin on SIRT1, Ac-p65Lys310 and pro-inflammatory factors in macrophages.

CONCLUSION

Therefore, these results demonstrated for the first time that baicalin exerts its anti-inflammatory effects in obese adipose tissue macrophages mainly through suppressing JNK/SIRT1/p65 signaling. These findings amplified the mechanisms of baicalin and its potential to attenuate insulin resistance.

Unveiling the impact of TREM-2+ Macrophages in metabolic disorders

The Triggering Receptor Expressed on Myeloid cells 2 (TREM-2) has been widely known by its anti-inflammatory activity. It can be activated in response to microbes and tissue damage, leading to phagocytosis, autophagy, cell polarization and migration, counter inflammation, and tissue repair. So far, the receptor has been largely explored in neurodegenerative disorders, however, a growing number of studies have been investigating its contribution in different pathological conditions, including metabolic diseases, in which (resident) macrophages play a crucial role. In this regard, TREM-2 + macrophages have been implicated in the onset and development of obesity, atherosclerosis, and fibrotic liver disease. These macrophages can be detected in the brain, white adipose tissue, liver, and vascular endothelium. In this review we discuss how different murine models have been demonstrating the ability of such cells to contribute to tissue and body homeostasis by phagocytosing cellular debris and lipid structures, besides contributing to lipid homeostasis in metabolic diseases. Therefore, understanding the role of TREM-2 in metabolic disorders is crucial to expand our current knowledge concerning their immunopathology as well as to foster the development of more targeted therapies to treat such conditions.

Relationship between CCL25/CCR9 Levels in Follicular Fluid and High Ovarian Response in Patients with Polycystic Ovary Syndrome

Objective

Polycystic ovary syndrome (PCOS) is one of the prevalent gynecological endocrine disorders encountered in clinical practice. Women diagnosed with PCOS demonstrate increased ovarian responsiveness, rendering them more prone to ovarian hyperstimulation syndrome (OHSS) during controlled ovarian stimulation (COS) procedures. The current study aimed at investigating whether CCL25/CCR9 plays a role in the pathological process of high ovarian response (HOR) during COS procedures.

Design

Single-center retrospective cohort study. Patients. A total of 200 PCOS patients who received a fixed regimen of gonadotropin-releasing hormone (GnRH) antagonist were enrolled in this study. The cohort comprised 118 patients exhibiting HOR and 82 patients demonstrating a normal ovarian response (NOR).

Results

The age and body mass index (BMI) variances across the two groups did not differ significantly. Similarly, the two groups observed no statistically significant differences in the baseline levels of luteinizing hormone (LH), progesterone (P), estradiol (E2), basal prolactin (PRL), and testosterone (T). Compared to the NOR group, HOR patients exhibit markedly elevated levels of anti-Müllerian hormone (AMH), antral follicle count (AFC), basal follicle-stimulating hormone (FSH), and HOMA-IR (all p  <  0.05). Conversely, no statistically significant differences were observed between the two groups with respect to COS parameters, encompassing initial gonadotropin (Gn) dose, stimulation duration, and total Gn dose. During COS, the number of oocytes with diameter ≥14 mm, the levels of E2 on the HCG day, and the number of retrieved oocytes were significantly higher in the HOR group than in the NOR group (all p < 0.001). Additionally, the levels of CCL25/CCR9, matrix metalloproteinases (MMPs), tissue inhibitor of metalloproteinases (TIMPs), TNF-α, and IL-6 were significantly higher in the FF of the HOR group than in the NOR group (all p < 0. 001), while the variance in IL-1β levels between the two cohorts did not reach statistical significance. The relevance analysis results indicated that the levels of CCL25/CCR9 in the FF of the HOR group are positively correlated with the number of retrieved oocytes and oocytes with diameters ≥14 mm during COS, AMH levels, and AFC. Concurrently, the CCL25 levels in the FF of the HOR group were positively correlated with HOMA-IR. Multivariable linear regression analysis revealed that the elevated AFC and HOMA-IR independently increase the CCL25 levels.

Conclusion

The CCL25/CCR9 levels in FF are positively correlated with the clinical indicators of HOR, suggesting that CCL25/CCR9 may play a role in the pathogenesis of HOR in patients with PCOS.

Rationale and Protocol of the ETERNITY-ITA Study: Use of Etelcalcetide for Preserving Vitamin K-Dependent Protein Activity-An Italian Study

Background/Objectives: Chronic kidney disease and mineral bone disorders (CKD-MBD) are frequently associated with an increased risk of both vascular calcifications (VCs) and bone fractures (BFs). The complex pathogenesis of VCs and BFs involves various factors such as calcium overload, phosphate imbalance, and secondary hyperparathyroidism. Key players, such as the vitamin K-dependent proteins (VKDPs) matrix Gla protein (MGP) and bone Gla protein (BGP), have pivotal roles both for VCs and BFs. The VIKI study highlighted that hemodialysis patients treated with calcimimetics had higher levels of total BGP and MGP compared to those untreated, suggesting a potential protective effect of these drugs on BFs and VCs beyond the beneficial effect of reducing PTH levels. Methods: ETERNITY-ITA is a multi-center, comparative effectiveness, observational, longitudinal study that will enroll 160 hemodialysis patients (80 patients treated with Etelcalcetide and 80 age- and sex-matched patients treated with calcitriol or vitamin D analogs). Nephrologists will tailor the target dose of Etelcalcetide on an individual level to achieve the KDIGO PTH target. In the Etelcalcetide-treated group, the addition of calcitriol will be allowed when required by clinical practice (for correction of hypocalcemia). Conclusions: This study will evaluate the real-world effect of Etelcalcetide on VKDP levels, such as BGP and MGP, at 3, 9, and 18 months from baseline. The resulting preservation of vascular and bone health will be assessed for the first time by examining aortic and iliac artery calcifications and vertebral fractures, respectively.

Role of complement factor D in cardiovascular and metabolic diseases

In the genesis and progression of cardiovascular and metabolic diseases (CVMDs), adipose tissue plays a pivotal and dual role. Complement factor D (CFD, also known as adipsin), which is mainly produced by adipocytes, is the rate-limiting enzyme of the alternative pathway. Abnormalities in CFD generation or function lead to aberrant immune responses and energy metabolism. A large number of studies have revealed that CFD is associated with CVMDs. Herein, we will review the current studies on the function and mechanism of CFD in CVMDs such as hypertension, coronary heart disease, ischemia/reperfusion injury, heart failure, arrhythmia, aortic aneurysm, obesity, insulin resistance, and diabetic cardiomyopathy.

Sex-specific response of the human plasma lipidome to short-term cold exposure

Cold-induced lipolysis is widely studied as a potential therapeutic strategy to combat metabolic disease, but its effect on lipid homeostasis in humans remains largely unclear. Blood plasma comprises an enormous repertoire in lipids allowing insights into whole body lipid homeostasis. So far, reported results originate from studies carried out with small numbers of male participants. Here, the blood plasma's lipidome of 78 male and 93 female volunteers, who were exposed to cold below the shivering threshold for 2 h, was quantified by comprehensive lipidomics using high-resolution mass spectrometry. Short-term cold exposure increased the concentrations in 147 of 177 quantified circulating lipids and the response of the plasma's lipidome was sex-specific. In particular, the amounts of generated glycerophospholipid and sphingolipid species differed between the sexes. In women, the BMI could be related with the lipidome's response. A logistic regression model predicted with high sensitivity and specificity whether plasma samples were from male or female subjects based on the cold-induced response of phosphatidylcholine (PC), lysophosphatidylcholine (LPC), and sphingomyelin (SM) species. In summary, cold exposure promotes lipid synthesis by supplying fatty acids generated after lipolysis for all lipid classes. The plasma lipidome, i.e. PC, LPC and SM, shows a sex-specific response, indicating a different regulation of its metabolism in men and women. This supports the need for sex-specific research and avoidance of sex bias in clinical trials.

Activin E upregulates uncoupling protein 1 and fibroblast growth factor 21 in brown adipocytes

Activin E activates brown and beige adipocytes and has been controversially implicated as a factor that induces obesity and fatty liver. Here, we sought to address this controversial issue by producing recombinant human activin E to evaluate its effects on HB2 brown adipocytes in vitro. Activin E increased uncoupling protein 1 (Ucp1) and fibroblast growth factor 21 (Fgf21) mRNA expression in the adipocytes. This upregulation was suppressed by SB431542, an inhibitor of activin receptor-like kinase (Alk) TGF-β type I receptors. SB431542 also inhibited the activin E-induced phosphorylation of Smad2/3. A promoter assay using a CAGA-Luc reporter and Alk expression vectors revealed that activin E activated the TGF-β/activin pathway via Alk7. The upregulation of Ucp1 and Fgf21 mRNA might be mediated through Alk7 and Smad2/3 phosphorylation. Activin E is a potential stimulator of energy expenditure by activating brown adipocytes and highlights its potential as a therapeutic target for treating obesity.

IRX3 promotes adipose tissue browning and inhibits fibrosis in obesity-resistant mice

Obesity is one of the threats to human health and survival. High fat diet (HFD)-induced obesity leads to adipose tissue fibrosis and a series of metabolic diseases. There are some people still thin under HFD, a phenomenon known as the "obesity resistance (OR) phenotype". It was found that Iroquois homeobox 3 (IRX3) is considered as a regulator in obesity, but the regulatory mechanism between OR and IRX3 is still unclear. In this study, we investigated OR on a HFD and the role of the IRX3 gene. Using mice, we observed that OR mice had lower body weights, reduced liver lipid synthesis, and increased white adipose tissue (WAT) lipolysis compared to obesity-prone (OP) mice. Additionally, OR mice exhibited spontaneous WAT browning and less fibrosis, correlating with higher Irx3 expression. Utilizing 3T3-L1 differentiated adipocytes, our study demonstrated that overexpression of Irx3 promoted thermogenesis-related gene expression and reduced adipocyte fibrosis. Therefore, Irx3 promotes WAT browning and inhibits fibrosis in OR mice. These results provide insight into the differences between obesity and OR, new perspectives on obesity treatment, and guidance for lessening adipose tissue fibrosis.

FAM210A: An emerging regulator of mitochondrial homeostasis

Mitochondrial homeostasis serves as a cornerstone of cellular function, orchestrating a delicate balance between energy production, redox status, and cellular signaling transduction. This equilibrium involves a myriad of interconnected processes, including mitochondrial dynamics, quality control mechanisms, and biogenesis and degradation. Perturbations in mitochondrial homeostasis have been implicated in a wide range of diseases, including neurodegenerative diseases, metabolic syndromes, and aging-related disorders. In the past decades, the discovery of numerous mitochondrial proteins and signaling has led to a more complete understanding of the intricate mechanisms underlying mitochondrial homeostasis. Recent studies have revealed that Family with sequence similarity 210 member A (FAM210A) is a novel nuclear-encoded mitochondrial protein involved in multiple aspects of mitochondrial homeostasis, including mitochondrial quality control, dynamics, cristae remodeling, metabolism, and proteostasis. Here, we review the function and physiological role of FAM210A in cellular and organismal health. This review discusses how FAM210A acts as a regulator on mitochondrial inner membrane to coordinate mitochondrial dynamics and metabolism.

Walnut extract protects against hepatic inflammation and toxicity induced by a high-fat diet

A high-fat diet (HFD) is one of the main causes of obesity and metabolic diseases. The liver is particularly affected by HFD causing metabolic dysfunction associated with fatty liver disease. Therefore, different strategies are used to mitigate the negative effects of HFD. This study aimed to assess the protective effects of walnut extract against HFD-induced toxicity in mice. The mice were fed HFD and walnut extract alone or in combination. The walnut extract was analyzed for composition using high-performance liquid chromatography with a diode array detector (HPLC-DAD) and ultra-high-performance liquid chromatography with mass spectrometry (UHPLC-MS/MS). Serum lipid profile; liver histology; hepatic antioxidants such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), lipid peroxidation (TBARS), and reduced glutathione (GSH); inflammatory markers like IL-6 and TNF-α; and phospholipids were determined. Results showed that phenolic acids, epicatechin, catechin, benzaldehyde, and juglone were the main constituents in the extract. The HFD group showed increased hepatic fat accumulation as evidenced by biochemical and histopathological examinations compared to the control animals. The HFD group mice also showed increased body and cardiac weights, modified lipid profiles, decreased antioxidant status, and increased levels of hepatic inflammatory markers. The weights of the body and heart, lipid profiles, antioxidant contents (CAT, SOD, GSH-Px, TBARS, and GSH), and pro-inflammatory cytokines (IL-6 and TNF-α) were all normalized by consuming walnut extract. Similarly, the HFD group had significantly high amounts of hepatic lipase, phospholipid, and lysophospholipid levels, which were improved by walnut extract. In conclusion, walnut extract has been shown to play a unique role in promoting the recovery of liver damage caused by a high-fat diet.

Disruption of nucleotide biosynthesis reprograms mitochondrial metabolism to inhibit adipogenesis

A key organismal response to overnutrition involves the development of new adipocytes through the process of adipogenesis. Preadipocytes sense changes in the systemic nutrient status and metabolites can directly modulate adipogenesis. We previously identified a role of de novo nucleotide biosynthesis in adipogenesis induction, whereby inhibition of nucleotide biosynthesis suppresses the expression of the transcriptional regulators PPARγ and C/EBPα. Here, we set out to identify the global transcriptomic changes associated with the inhibition of nucleotide biosynthesis. Through RNA sequencing (RNAseq), we discovered that mitochondrial signatures were the most altered in response to inhibition of nucleotide biosynthesis. Blocking nucleotide biosynthesis induced rounded mitochondrial morphology, and altered mitochondrial function, and metabolism, reducing levels of tricarboxylic acid cycle intermediates, and increasing fatty acid oxidation (FAO). The loss of mitochondrial function induced by suppression of nucleotide biosynthesis was rescued by exogenous expression of PPARγ. Moreover, inhibition of FAO restored PPARγ expression, mitochondrial protein expression, and adipogenesis in the presence of nucleotide biosynthesis inhibition, suggesting a regulatory role of nutrient oxidation in differentiation. Collectively, our studies shed light on the link between substrate oxidation and transcription in cell fate determination.

Sarcopenic obesity and osteoporosis: Research progress and hot spots

Sarcopenic obesity (SO) and osteoporosis (OP) are associated with aging and obesity. The pathogenesis of SO is complex, including glucolipid and skeletal muscle metabolic disorders caused by inflammation, insulin resistance, and other factors. Growing evidence links muscle damage to bone loss. Muscle-lipid metabolism disorders of SO disrupt the balance between bone formation and bone resorption, increasing the risk of OP. Conversely, bones also play a role in fat and muscle metabolism. In the context of aging and obesity, the comprehensive review focuses on the effects of mechanical stimulation, mesenchymal stem cells (MSCs), chronic inflammation, myokines, and adipokines on musculoskeletal, at the same time, the impact of osteokines on muscle-lipid metabolism were also analyzed. So far, exercise combined with diet therapy is the most effective strategy for increasing musculoskeletal mass. A holistic treatment of musculoskeletal diseases is still in the preliminary exploration stage. Therefore, this article aims to improve the understanding of musculoskeletal -fat interactions in SO and OP, explores targets that can provide holistic treatment for SO combined with OP, and discusses current limitations and challenges. We hope to provide relevant ideas for developing specific therapies and improving disease prognosis in the future.

Whole-genome resequencing identifies candidate genes associated with heat adaptation in chickens

The wide distribution and diverse varieties of chickens make them important models for studying genetic adaptation. The aim of this study was to identify genes that alter heat adaptation in commercial chicken breeds by comparing genetic differences between tropical and cold-resistant chickens. We analyzed whole-genome resequencing data of 186 chickens across various regions in Asia, including the following breeds: Bian chickens (B), Dagu chickens (DG), Beijing-You chickens (BY), and Gallus gallus jabouillei from China; Gallus gallus murghi from India; Vietnam native chickens (VN); Thailand native chickens (TN) and Gallus gallus spadiceus from Thailand; and Indonesia native chickens (IN), Gallus gallus gallus, and Gallus gallus bankiva from Indonesia. In total, 5,454,765 SNPs were identified for further analyses. Population genetic structure analysis revealed that each local chicken breed had undergone independent evolution. Additionally, when K = 5, B, BY, and DG chickens shared a common ancestor and exhibited high levels of inbreeding, suggesting that northern cold-resistant chickens are likely the result of artificial selection. In contrast, the runs of homozygosity (ROH) and the ROH-based genomic inbreeding coefficient (FROH) results for IN, TN, and VN chickens showed low levels of inbreeding. Low population differentiation index values indicated low differentiation levels, suggesting low genetic diversity in tropical chickens, implying increased vulnerability to environmental changes, decreased adaptability, and disease resistance. Whole-genome selection sweep analysis revealed 69 candidate genes, including LGR4, G6PC, and NBR1, between tropical and cold-resistant chickens. The genes were further subjected to GO and KEGG enrichment analyses, revealing that most of the genes were primarily enriched in biological synthesis processes, metabolic processes, central nervous system development, ion transmembrane transport, and the Wnt signaling pathway. Our study identified heat adaptation genes and their functions in chickens that primarily affect chickens in high-temperature environments through metabolic pathways. These heat-resistance genes provide a theoretical basis for improving the heat-adaptation capacity of commercial chicken breeds.

Transcriptional control of metabolism by interferon regulatory factors

Interferon regulatory factors (IRFs) comprise a family of nine transcription factors in mammals. IRFs exert broad effects on almost all aspects of immunity but are best known for their role in the antiviral response. Over the past two decades, IRFs have been implicated in metabolic physiology and pathophysiology, partly as a result of their known functions in immune cells, but also because of direct actions in adipocytes, hepatocytes, myocytes and neurons. This Review focuses predominantly on IRF3 and IRF4, which have been the subject of the most intense investigation in this area. IRF3 is located in the cytosol and undergoes activation and nuclear translocation in response to various signals, including stimulation of Toll-like receptors, RIG-I-like receptors and the cGAS-STING pathways. IRF3 promotes weight gain, primarily by inhibiting adipose thermogenesis, and also induces inflammation and insulin resistance using both weight-dependent and weight-independent mechanisms. IRF4, meanwhile, is generally pro-thermogenic and anti-inflammatory and has profound effects on lipogenesis and lipolysis. Finally, new data are emerging on the role of other IRF family members in metabolic homeostasis. Taken together, data indicate that IRFs serve as critical yet underappreciated integrators of metabolic and inflammatory stress.

Maintenance of thermogenic adipose tissues despite loss of the H3K27 acetyltransferases p300 or CBP

Brown and beige adipose tissues are specialized for thermogenesis and are important for energy balance in mice. Mounting evidence suggests that chromatin-modifying enzymes are integral for the development, maintenance, and functioning of thermogenic adipocytes. p300 and cAMP-response element binding protein (CREB)-binding protein (CBP) are histone acetyltransferases (HATs) responsible for writing the transcriptionally activating mark H3K27ac. Despite their homology, p300 and CBP do have unique tissue- and context-dependent roles, which have yet to be examined in brown and beige adipocytes specifically. We assessed the requirement of p300 or CBP in thermogenic fat using uncoupling protein 1 (Ucp1)-Cre-mediated knockdown in mice to determine whether their loss impacted tissue development, susceptibility to diet-induced obesity, and response to pharmacological induction via β3-agonism. Despite successful knockdown, brown adipose tissue mass and expression of thermogenic markers were unaffected by loss of either HAT. As such, knockout mice developed a comparable degree of diet-induced obesity and glucose intolerance to that of floxed controls. Furthermore, "browning" of white adipose tissue by the β3-adrenergic agonist CL-316,243 remained largely intact in knockout mice. Although p300 and CBP have nonoverlapping roles in other tissues, our results indicate that they are individually dispensable within thermogenic fats specifically, possibly due to functional compensation by one another.NEW & NOTEWORTHY The role of transcriptionally activating H3K27ac epigenetic mark has yet to be examined in mouse thermogenic fats specifically, which we achieved here via Ucp1-Cre-driven knockdown of the histone acetyltransferases (HAT) p300 or CBP under several metabolic contexts. Despite successful knockdown of either HAT, brown adipose tissue was maintained at room temperature. As such, knockout mice were indistinguishable to controls when fed an obesogenic diet or when given a β3-adrenergic receptor agonist to induce browning of white fat. Unlike other tissues, thermogenic fats are resilient to p300 or CBP ablation, likely due to sufficient functional overlap between them.

Irisin expression and FNDC5 (rs3480) gene polymorphism in type 2 diabetic patients with and without CAD

BACKGROUND

Irisin was found to correlate with coronary artery disease (CAD) in diabetic patients. This study investigated the association of irisin and FNDC5 (SNP rs3480) with the presence and severity of CAD in T2DM.

METHODS

This cross-sectional study included 100 patients with T2DM divided into two groups, DM group (n = 50), including patients without CAD and CAD group (n = 50), including those confirmed to have CAD by coronary angiography. Irisin was measured. SNP rs3480 genotyping of FNDC5 was done.

RESULTS

Irisin levels were significantly lower in the CAD group (p < 0.001). The CAD group had significantly higher HbA1c and lower HDL (p < 0.001). Patients with controlled DM had significantly higher irisin levels (p < 0.001). single nucleotide polymorphism (SNP) rs3480 was not associated with irisin levels, and the FNDC5 rs3480 AA reference allele was significantly associated with significant CAD.

CONCLUSION

Irisin appears to be protective against developing CAD in diabetic patients. Irisin level was an independent predictor of significant CAD in diabetic patients combined with the FNDC5 rs3480 genotype.

CLINICAL TRIAL REGISTRATION NUMBER

NCT04957823.

Neuronal glucose sensing mechanisms and circuits in the control of insulin and glucagon secretion

Glucose homeostasis is mainly under the control of the pancreatic islet hormones insulin and glucagon, which, respectively, stimulate glucose uptake and utilization by liver, fat, and muscle and glucose production by the liver. The balance between the secretions of these hormones is under the control of blood glucose concentrations. Indeed, pancreatic islet β-cells and α-cells can sense variations in glycemia and respond by an appropriate secretory response. However, the secretory activity of these cells is also under multiple additional metabolic, hormonal, and neuronal signals that combine to ensure the perfect control of glycemia over a lifetime. The central nervous system (CNS), which has an almost absolute requirement for glucose as a source of metabolic energy and thus a vital interest in ensuring that glycemic levels never fall below ∼5 mM, is equipped with populations of neurons responsive to changes in glucose concentrations. These neurons control pancreatic islet cell secretion activity in multiple ways: through both branches of the autonomic nervous system, through the hypothalamic-pituitary-adrenal axis, and by secreting vasopressin (AVP) in the blood at the level of the posterior pituitary. Here, we present the autonomic innervation of the pancreatic islets; the mechanisms of neuron activation by a rise or a fall in glucose concentration; how current viral tracing, chemogenetic, and optogenetic techniques allow integration of specific glucose sensing neurons in defined neuronal circuits that control endocrine pancreas function; and, finally, how genetic screens in mice can untangle the diversity of the hypothalamic mechanisms controlling the response to hypoglycemia.

Aged microbiota exacerbates cardiac failure by PPARα/PGC1α pathway

The dysbiosis of gut microbiota with aging has been extensively studied, revealing its substantial contribution to variety of diseases. However, the impact of aged microbiota in heart failure (HF) remains unclear. In this study, we employed the method of fecal microbiota transplantation (FMT) from aged donors to investigate its role in the context of HF. Our results demonstrate that FMT from aged donors alters the recipient's gut microbiota composition and abundance. Furthermore, FMT impairs cardiac function and physical activity in HF mice. Aged FMT induces metabolic alterations, leading to body weight gain, impaired glucose tolerance, increased respiratory exchange ratio, and enhanced fat accumulation. The epicardium of aged FMT recipients shows fat accumulation, accompanied by cardiomyocyte hypertrophy, cardiac fibrosis and increased cellular apoptosis. Mechanistically, aged FMT suppresses the PPARα/PGC1α signaling pathway in HF. Notably, activation of PPARα effectively rescues the metabolic changes and myocardial injury caused by aged FMT. In conclusion, our study emphasizes the role of the PPARα/PGC1α signaling pathway in aged FMT-mediated HF.

Effect of irisin on ovarian phosphatidylinositol-3-kinase/protein kinase B signaling pathway and mitogen-activated protein kinase/extracellular signal-regulated kinase pathways of rats with polycystic ovary syndrome

OBJECTIVE

To investigate the independent effects of irisin on insulin resistance (IR) in ovary of polycystic ovary syndrome (PCOS) and explore possible pathways.

METHODS

We established PCOS medel using Poretsky L's method, then PCOS rats were randomly divided into model group (M) and irisin group (I), and normal rats (N) were used as the control. Then rats in the group I were injected with recombinant irisin. Then the levels of circulating fasting blood glucose (FBG), fasting insulin (FINS), homeostasis model assessment of IR (HOMA-IR) and PI3K/AKT and MAPK/ERK pathways in each group were observed, as well as the effects of irisin on the levels of circulating HOMA-IR and PI3K/AKT and MAPK/ERK pathways in ovary of PCOS rats were evaluated.

RESULTS

Compared with normal group, levels of FBG, FINS, and HOMA-IR of model group were significantly increased (p < 0.001, p < 0.001, and p < 0.001, respectively), levels of average optical density by IHC of p-PI3K, PI3K, p-AKT, and AKT (p = 0.015, p = 0.010, p = 0.005, and p = 0.009, respectively) and levels of mRNA concentration of PI3K and AKT (p = 0.001, and p = 0.005, respectively) were decreased, while the levels of average optical density of p-ERK, ERK (p = 0.011, and p = 0.013, respectively) and level of mRNA concentration of ERK (p < 0.001) were increased in ovary. After irisin intervention, compared with model group, levels of FBG, FINS, and HOMA-IR of rats in irisin group were significantly decreased (p = 0.001, p < 0.001, and p < 0.001, respectively), levels of average optical density by IHC of p-PI3K, PI3K, p-AKT, and AKT (p = 0.030, p = 0.024, p = 0.012, and p = 0.025, respectively) and levels of mRNA concentration of PI3K and AKT (p = 0.002, and p = 0.003, respectively) were significantly increased, while the levels of average optical density of p-ERK, ERK (p = 0.004, and p = 0.026, respectively) and level of mRNA concentration of ERK (p = 0.001) were significantly decreased.

CONCLUSION

Our study demonstrated that irisin could not only improve circulating insulin resistance, but may also improve ovarian IR through an increase in the activity of PI3K/AKT signaling and a decrease of MAPK/ERK signaling.

Impact of different hormones on the regulation of nitric oxide in diabetes

Polymetabolic syndrome achieved pandemic proportions and dramatically influenced public health systems functioning worldwide. Chronic vascular complications are the major contributors to increased morbidity, disability, and mortality rates in diabetes patients. Nitric oxide (NO) is among the most important vascular bed function regulators. However, NO homeostasis is significantly deranged in pathological conditions. Additionally, different hormones directly or indirectly affect NO production and activity and subsequently act on vascular physiology. In this paper, we summarize the recent literature data related to the effects of insulin, estradiol, insulin-like growth factor-1, ghrelin, angiotensin II and irisin on the NO regulation in physiological and diabetes circumstances.

Neuregulin 4 Attenuates Podocyte Injury and Proteinuria in Part by Activating AMPK/mTOR-Mediated Autophagy in Mice

In this study, we investigate the effect of neuregulin 4 (NRG4) on podocyte damage in a mouse model of diabetic nephropathy (DN) and we elucidate the underlying molecular mechanisms. In vivo experiments were conducted using a C57BL/6 mouse model of DN to determine the effect of NRG4 on proteinuria and podocyte injury, and in vitro experiments were performed with conditionally immortalized mouse podocytes treated with high glucose and NRG4 to assess the protective effects of NRG4 on podocyte injury. Autophagy-related protein levels and related signaling pathways were evaluated both in vivo and in vitro. The involvement of the adenosine monophosphate-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) pathway was detected using chloroquine or AMPK inhibitors. The results showed that the AMPK/mTOR pathway was involved in the protective roles of NRG4 against high glucose-mediated podocyte injury. Also, NRG4 significantly decreased albuminuria in DN mice. PAS staining indicated that NRG4 mitigated glomerular volume and mesangium expansion in DN mice. Consistently, western blot and RT-PCR analyses confirmed that NRG4 decreased the expression of pro-fibrotic molecules in the glomeruli of DN mice. The immunofluorescence results showed that NRG4 retained expression of podocin and nephrin, whereas transmission electron microscopy revealed that NRG4 alleviated podocyte injury. In DN mice, NRG4 decreased podocyte apoptosis and increased expression of nephrin and podocin, while decreasing the expression of desmin and HIF1α. Overall, NRG4 improved albuminuria, glomerulosclerosis, glomerulomegaly, and hypoxia in DN mice. The in vitro experiments showed that NRG4 inhibited HG-induced podocyte injury and apoptosis. Furthermore, autophagy of the glomeruli decreased in DN mice, but reactivated following NRG4 intervention. NRG4 intervention was found to partially activate autophagy via the AMPK/mTOR signaling pathway. Consequently, when the AMPK/mTOR pathway was suppressed or autophagy was inhibited, the beneficial effects of NRG4 intervention on podocyte injury were diminished. These results indicate that NRG4 intervention attenuates podocyte injury and apoptosis by promoting autophagy in the kidneys of DN mice, in part, by activating the AMPK/mTOR signaling pathway.