Positional cloning of the mouse obese gene and its human homologue

A Bird's-Eye Overview of Leptin and Female Reproduction -with Mammalian Comparisons

Leptin, a key regulator of reproductive physiology, influences various processes in vertebrates, including oocyte proliferation, embryogenesis, the onset of puberty, ovarian function, and follicle development. In mammals, leptin affects steroidogenesis, folliculogenesis, and hormonal regulation through the hypothalamic-pituitary-gonadal axis. Instead, in avian species, leptin-controlled mechanisms are poorly understood, because birds do not produce leptin in adipocytes. In birds, leptin is expressed in the brain, pituitary glands, and gonads, where it enhances ovarian function and egg-laying performance, particularly during feed deprivation. In this review, we discuss and summarize the recently discovered role of leptin in regulating ovarian function during different life stages in birds and compare it with its function in mammals.

Leptin, NK cells, and the weight of immunity: Insights into obesity

Obesity is a chronic inflammatory disease that affects more than 1 billion people worldwide and is associated with various metabolic and physiological dysfunctions, directly impacting the dynamics of the immune response, partly due to elevated leptin levels. Leptin is an important peptide hormone that regulates neuroendocrine function and energy homeostasis, with its blood levels reflecting energy reserves, fat mass, or energy deprivation. This hormone also plays a fundamental role in regulating immune function, including the activity of NK cells, which are essential components in antiviral and antitumor activity. In obese individuals, leptin resistance is commonly established, however, NK cells and other immune components remain responsive to this hormone. So far, leptin has demonstrated paradoxical activities of these cells, often associated with a dysfunctional profile when associated with obesity. The excessive fat is usually related to metabolic remodeling in NK cells, resulting in compromised antitumor responses due to reduced cytotoxic capacity and decreased expression of cytokines important for these defense mechanisms, such as IFN-γ. Therefore, this review approaches a better understanding of the immunoendocrine interactions between leptin and NK cells in the context of obesity.

Hunger Games: A Modern Battle Between Stress and Appetite

Stress, an evolutionarily adaptive mechanism, has become a pervasive challenge in modern life, significantly impacting feeding-relevant circuits that play a role in the development and pathogenesis of eating disorders (EDs). Stress activates the hypothalamic-pituitary-adrenal (HPA) axis, disrupts specific neural circuits, and dysregulates key brain regions, including the hypothalamus, hippocampus, and lateral septum. These particular structures are interconnected and key in integrating stress and feeding signals, modulating hunger, satiety, cognition, and emotional coping behaviors. Here we discuss the interplay between genetic predispositions and environmental factors that may exacerbate ED vulnerability. We also highlight the most commonly used animal models to study the mechanisms driving EDs and recent rodent studies that emphasize the discovery of novel cellular and molecular mechanisms integrating stress and feeding signals within the hippocampus-lateral septum-hypothalamus axis. In this review, we discuss the role of gut microbiome, an emerging area of research in the field of EDs and unanswered questions that persist and hinder the scientific progress, such as why some individuals remain resilient to stress while others become at high risk for the development of EDs. We finally discuss the need for future research delineating the impact of specific stressors on neural circuits, clarifying the relevance and functionality of hippocampal-septal-hypothalamic connectivity, and investigating the role of key neuropeptides such as CRH, oxytocin, and GLP-1 in human ED pathogenesis. Emerging tools like single-cell sequencing and advanced human imaging could uncover cellular and circuit-level changes in brain areas relevant for feeding in ED patients. Ultimately, by integrating basic and clinical research, science offers promising avenues for developing personalized, mechanism-based treatments targeting maladaptive eating behavior for patients suffering from EDs.

Obesity: a 100 year perspective

This review has examined the scientific basis for our current understanding of obesity that has developed over the past 100 plus years. Obesity was defined as an excess of body fat. Methods of establishing population and individual changes in levels of excess fat are discussed. Fat cells are important storage site for excess nutrients and their size and number affect the response to insulin and other hormones. Obesity as a reflection of a positive fat balance is influenced by a number of genetic and environmental factors and phenotypes of obesity can be developed from several perspectives, some of which have been elaborated here. Food intake is essential for maintenance of human health and for the storage of fat, both in normal amounts and in obesity in excess amounts. Treatment approaches have taken several forms. There have been numerous diets, behavioral approaches, along with the development of medications.. Bariatric/metabolic surgery provides the standard for successful weight loss and has been shown to have important effects on future health. Because so many people are classified with obesity, the problem has taken on important public health dimensions. In addition to the scientific background, obesity through publications and organizations has developed its own identity. While studying the problem of obesity this reviewer developed several aphorisms about the problem that are elaborated in the final section of this paper.

Mechanisms and pharmacotherapy of cancer cachexia-associated anorexia

Cachexia is a multifactorial metabolic syndrome characterized by weight and skeletal muscle loss caused by underlying illnesses such as cancer, heart failure, and renal failure. Inflammation, insulin resistance, increased muscle protein degradation, decreased food intake, and anorexia are the primary pathophysiological drivers of cachexia. Cachexia causes physical deterioration and functional impairment, loss of quality of life, lower response to active treatment, and ultimately morbidity and mortality, while the difficulties in tackling cachexia in its advanced phases and the heterogeneity of the syndrome among patients require an individualized and multidisciplinary approach from an early stage. Specifically, strategies combining nutritional and exercise interventions as well as pharmacotherapy that directly affect the pathogenesis of cachexia, such as anti-inflammatory, metabolism-improving, and appetite-stimulating agents, have been proposed, but none of which have demonstrated sufficient evidence to date. Nevertheless, several agents have recently emerged, including anamorelin, a ghrelin receptor agonist, growth differentiation factor 15 neutralization therapy, and melanocortin receptor antagonist, as candidates for ameliorating anorexia associated with cancer cachexia. Therefore, in this review, we outline cancer cachexia-associated anorexia and its pharmacotherapy, including corticosteroids, progesterone analogs, cannabinoids, anti-psychotics, and thalidomide which have been previously explored for their efficacy, in addition to the aforementioned novel agents, along with their mechanisms.

Hormonology: A kaleidoscopic tale of dedication, serendipity, and ingenuity

This article delves into stories of hormone discovery, characterization, clinical application, and the scientists themselves. Our journey begins with Arnold Berthod's rooster castration experiments, laying the groundwork for understanding testosterone, and Ernest Starling's 1902 revelation that secretin wasn't neuron-released. We'll explore the origins of kisspeptin and its role in Gonadotropin-releasing hormone pulsatile secretion by KNDY neurons. Discussions will then include the isolation of Growth hormone-releasing hormone from pancreatic tumors and growth hormone therapy's surprising link to Creutzfeldt-Jakob disease. We'll also delve into the design of long-acting follicle stimulating hormone for infertility treatment, alongside discoveries of five inhibin and activin hormones. Further, we'll uncover the discovery of receptors for relaxin family ligands and diverse chemokines, highlighting scientists' use of evolutionary genomics. We'll touch on parabiotic animal experiments leading to leptin's discovery and polarized ligand-receptor expression for receptor activation. The narrative will include instances such as a Nobel laureate who presented a rejection letter received prior to their award ceremony and a researcher pursuing receptor structure despite funding setbacks, both eventually rewarded. Through the diligent efforts of researchers and unexpected discoveries, the mechanisms of more than a hundred hormones have been elucidated. The endocrinological research domain is currently embracing the application of artificial intelligence to analyze extensive genomic and protein structure databases.

Maternal Serum and Cord Blood Leptin Concentrations in African Newborns: Relationship to Birth Weight and Gender

BACKGROUND

Leptin, a protein predominantly produced by adipocytes, plays a crucial role in regulating energy balance, inflammation, immunity, and fetal growth. During pregnancy, maternal serum leptin levels increase, peaking in the second trimester, with placental production contributing to this rise. Leptin has also been identified in fetal tissues, and its concentration in umbilical cord blood correlates with birth weight. This study aimed to evaluate serum and umbilical cord blood leptin concentrations in rural Burundian women living in marginal nutritional conditions, and investigate potential gender differences in fetal leptin levels.

METHODS

We analyzed data from 38 healthy singleton pregnancies (20 male and 18 female newborns) delivered at Hôpital Autonome de Ngozi, Burundi. Leptin concentrations were measured in maternal and umbilical cord blood samples.

RESULTS

Our results revealed that neonatal leptin levels were significantly higher in female compared to male newborns, consistent with findings in other populations. Leptin concentrations in umbilical cord blood were positively correlated with neonatal birth weight and the Kaup index, while maternal leptin levels did not show such associations.

CONCLUSIONS

Despite the challenging nutritional environment in this rural African setting, our findings suggest that leptin's role in fetal growth regulation may transcend maternal nutritional status. The gender difference observed in leptin levels could be linked to genetic or epigenetic factors rather than fat content or reproductive hormones. This study supports the notion that leptin may be an important regulator of fetal development, even in malnourished populations, and underscores the need for further research to elucidate its mechanisms in pregnancy.

Evaluation of the effects of obesity on orthodontic tooth movement

Objective

This study aimed to evaluate bone remodeling in gingival crevicular fluid (GCF) during canine distalization in obese individuals and compare it to that in normal-weight individuals. Additionally, the orthodontic tooth movement rates of obese individuals were measured and compared with those of normal-weight individuals.

Methods

Thirty-six patients (18 obese and 18 normal-weight) aged 12-18 years who were candidates for maxillary first premolar extraction for Angle Class II malocclusion were included in the study. The two groups were formed according to World Health Organization guidelines. A normal-weight group (body mass index [BMI] 16-85%) and an obese group (BMI ≥ 95%). Gingival crevicular fluid samples were collected before, 24 hours after, and on the 7th, 14th, and 21st days after the application of the distalization force. Enzyme-linked immunosorbent assay was used to measure leptin, receptor activator of nuclear factor kappa-Β ligand (RANKL), osteoprotegerin (OPG) and interleukin-6 (IL-6) levels in GCF samples. In addition to the recorded GCF sampling times, the amount of canine tooth movement was calculated using digital models obtained on the 28th day and 3rd month.

Results

Leptin, RANKL, OPG, and IL-6 levels were significantly higher in the obese group (P < 0.05). The digital model measurements displayed high rates of repeatability (ICC 0.990). The difference in the amount of tooth movement between groups was not statistically significant (P > 0.05).

Conclusions

Although obese and normal-weight individuals showed different biomarker levels during tooth movement, there were no significant differences in the amount of movement.

PCSK9 Expression in Vascular Smooth Muscle Cells: Role of Insulin Resistance and High Glucose

Beyond the regulation of cholesterol metabolism, a number of extrahepatic functions of proprotein convertase subtilisin/kexin type 9 (PCSK9) have been increasingly identified. The main purpose of this study was to verify whether PCSK9 expression in vascular smooth muscle cells (VSMC) is influenced by insulin resistance and high glucose (HG). In cultured rat aortic VSMC from lean insulin-sensitive Zucker rats (LZRs) and obese insulin-resistant Zucker rats (OZRs), a classical animal model of insulin resistance, we evaluated PCSK9 expression with or without the monoclonal antibodies against PCSK9 Alirocumab and Evolocumab or the synthetic PCSK9-binding peptide PEP 2-8. Effects and molecular mechanisms underlying altered PCSK9 expression were evaluated by proliferation and migration assay, reactive oxygen species (ROS) production, and involvement of PKC, NADPH-oxidase, MAPK/ERK-1/2 pathway activation. As a result, we found that, in comparison with LZR, VSMC from OZR showed basal PCSK9 overexpression mitigated by Alirocumab, Evolocumab, PEP 2-8, and the inhibitors of PKC, NADPH-oxidase, and MAPK. The finding of PCSK9 upregulation in VSMC from OZR paralleled with increased ROS production, proliferation, and migration. HG increased PCSK9 expression in VSMC from LZR, but not in OZR, via oxidative stress and with effects reduced by PCSK9 inhibitors. These findings suggest that a dysregulation of PCSK9 in VSMC could be involved in vascular damage in metabolic disorders, such as obesity and diabetes.

Serum levels of Wnt5a in Egyptian women with obesity and their association with toll like receptor 2 Arg753Gln gene polymorphism in a pilot case control study of obesity as a state of metaflammation

Female obesity is a worldwide health issue linked to chronic metabolic low-grade inflammation (metaflammation) causing multiple obesity-related co-morbid conditions. We aimed to assess the serum levels of wingless integration site family member 5 A (Wnt5a), leptin, and tumor necrosis factor-alpha (TNF-α) as markers of obesity-associated metaflammation and investigate the association with toll-like receptors2 (TLR2) gene (Arg753Gln) single nucleotide polymorphism (SNP) among Egyptian females. The study included 60 females with obesity and 30 matched controls. Serum levels of Wnt5a, leptin, and TNF-α were assessed by ELISA, while TLR2 (Arg753Gln) genotyping was done by PCR-RFLP. Serum Wnt5a, leptin, and TNF-α showed significantly higher levels in females with obesity than controls and a significant increase with higher classes of obesity. They showed significant positive correlations with each other. Only TNF-α and leptin were associated with metabolic syndrome (MetS) among the obesity group. According to TLR2 (Arg753Gln) SNP, the homozygous GG genotype was associated with elevated levels of Wnt5a, leptin, and TNF-α compared to the AA + GA model carriers. No significant differences were found in the distribution of TLR2 Arg753Gln (rs5743708) genotypes and alleles according to obesity or MetS, and the regression analysis showed no significant risk association. Serum Wnt5a, leptin, and TNF-α levels increase in women with obesity and the A allele of TLR2 (Arg753Gln) SNP could be protective against obesity-associated metaflammation.

Nesfatin-1 Neurons in the Ventral Premammillary Nucleus Integrate Metabolic and Reproductive Signals in Male Rats

The ability to reproduce depends on metabolic status. In rodents, the ventral premammillary nucleus (PMv) integrates metabolic and reproductive signals. While leptin (adiposity-related) signaling in the PMv is critical for female fertility, male reproductive functions are strongly influenced by glucose homeostasis. The anorexigenic peptide nesfatin-1 is a leptin-independent central regulator of blood glucose. Therefore, its integrative role in male rats can be assumed. To investigate this, we mapped the distribution of nesfatin-1 mRNA- and protein-producing cells in the PMv during postnatal development via in situ hybridization and immunohistochemistry, respectively. Fos-nesfatin-1, double immunostaining was used to determine the combined effect of heterosexual pheromone challenge and insulin-induced hypoglycemia on neuronal activation in adults. We found that ~75% of the pheromone-activated neurons were nesfatin-1 cells. Hypoglycemia reduced pheromone-induced cell activation, particularly in nesfatin-1 neurons. Immuno-electron microscopy revealed innervation of PMv nesfatin-1 neurons by urocortin3-immunoreactive terminals, reportedly originating from the medial amygdala. Nesfatin-1 immunopositive neurons expressed GPR10 mRNA, a receptor associated with metabolic signaling, but did not respond with accumulation of phosphorylated STAT3 immunopositivity, a marker of leptin receptor signaling, in response to intracerebroventricular leptin treatment. Our results suggest that PMv nesfatin-1 neurons are primarily responsible for integrating reproductive and metabolic signaling in male rats.

Recurrent depression predicts high leptin concentrations in patients with coronary artery disease over an 18-months follow-up period: Findings from the prospective multicenter randomized controlled SPIRR-CAD Trial

BACKGROUND

Leptin, an adipokine suspected to play a role in coronary artery disease (CAD), may also be associated with deteriorated mental health. We investigated the prospective impact of recurrent depressed mood (RDM) on heightened plasma leptin levels in CAD patients.

METHODS

Derived from the randomized SPIRR-CAD trial, plasma leptin were measured by the Human Leptin DuoSet ELISA at baseline in 539 patients (including 115 (21.3 %) women and 424 (78.7 %) men) and in 373 participants after 18-months follow up (T3). RDM was based on the clinical course from baseline to follow-up assessed by the Hamilton Depression Rating Scale (HAMD). Multivariate binary logistic regression models identified predictors for heightened leptin at T3.

RESULTS

At baseline, highest leptin level (3rd tertile) was associated with type 2 diabetes (p = 0.009), heart failure symptoms (NYHA III) (p < 0.001), female sex and BMI ≥30 (p < 0.001) but not with age and depression. At study endpoint (T3), RDM was associated with a substantially increased risk of experiencing the highest plasma leptin level (OR 2.92 (95 % CI 1.27-6.75)) followed by increased NT-proBNP (the most prominent indicator of CHF) with an OR of 2.73 (1.22-6.11) - both after adjustment for concurrent factors including weight gain (diff BMI T3-T1) over the study period - the latter accounting for an OR of 1.41 (1.17-1.70).

LIMITATIONS

Findings are limited to people of Caucasian ancestry which prevents being generalized to other ethnicities. Although relying upon a prospective design, reverse causality cannot be excluded but is unlikely.

CONCLUSIONS

In CAD patients, RDM is a significant predictor of heightened leptin -a finding opening room for a new pathway of the psychobiological underpinning of depression on CAD risk.

The research progress and prospects of circadian rhythm in obesity: a bibliometric analysis

Background

Numerous studies have shown a link between circadian rhythms disruptions and a higher risk of obesity. This article aims to conduct an extensive bibliometric analysis to deepen our understanding of the relationship between circadian rhythms and obesity.

Methods

The literature related to the circadian rhythm of obesity, published from the inception of the Web of Science Core Collection (WoSCC) until June 30, 2024, was extracted from the WoSCC databases (SCIE, SSCI, ESCI). Using CiteSpace, Vosviewer, WPS, and other software, this paper examines the publication trends, including the number of papers, countries/regions, institutions, authors, journals, references, and keywords.

Results

A total of 2,870 articles were included in this analysis, revealing a consistent year by year increase in research on the circadian rhythm of obesity. These publications originate from 460 institutions in 88 countries. Among the authors analysis, Garaulet, Marta was the most prolific, and Turek FW was the most co-cited. Proceedings of the National Academy of Sciences of the United States of America emerged as the journal with the highest number of publications, and American Journal of Physiology had the highest centrality. The most frequently used keywords were "obesity," "circadian rhythm," "circadian clock," "metabolic syndrome," "metabolism." Additionally, research areas involving intermittent fasting, restricted feeding, and gut microbiota were rapidly developing and represented the forefront of research on circadian rhythms and obesity.

Conclusion

Our study demonstrates that research on circadian rhythms in obesity has been rapidly expanding, with increasingly in-depth exploration of the topic. It is recommended to strengthen cooperation between countries and institutions to jointly promote research in this field. The gene expression of obesity is an early hotspot in the study of circadian rhythm and obesity, and emerging research areas such as intermittent fasting, restricted feeding, endothelial nitric oxide synthase and gut microbiota will become significant hotspots and trends in the field of circadian rhythm and obesity. These findings provide researchers critical directions for future studies and may have significant implications for clinical practice and public health policy.

Neuroglia in eating disorders (obesity, Prader-Willi syndrome and anorexia nervosa)

The hypothalamus is widely recognized as one of the most extensively studied brain regions involved in the central regulation of energy homeostasis. Within the hypothalamus, peptidergic neurons play a crucial role in monitoring peripheral concentrations of metabolites and hormones, and they finely adjust the sensing of these factors, leading to the activation of either anorexigenic (appetite-suppressing) or orexigenic (appetite-stimulating) pathways. While cortical innervation of the hypothalamus does influence these processes, it is generally considered of secondary importance. Eating-related disorders, such as obesity and anorexia nervosa, are strongly associated with imbalances in energy intake and expenditure. The phenotypes of these disorders can be attributed to dysfunctions in the hypothalamus. Traditionally, it has been believed that hypothalamic dysfunction in these disorders primarily stems from defects in neural pathways. However, recent evidence challenges this perception, highlighting the active participation of neuroglial cells in shaping both physiologic and behavioral characteristics. This review aims to provide an overview of the latest insights into glial biology in three specific eating disorders: obesity, Prader-Willi syndrome, and anorexia. In these disorders, neural dysfunction coincides with glial malfunction, suggesting that neuroglia actively contribute to the development and progression of various neurologic disorders. These findings underscore the importance of glial cells and open up potential new avenues for therapeutic interventions.

Brain receptor dynamics in early and adult life stress: Gateways to maladaptive coping strategies

Stress plays a significant role in the onset of numerous psychiatric disorders. Depending on individual resilience or stressor's nature, long-term changes to stress in the brain can lead to a wide range of behavioral symptoms, including social withdrawal, feelings of helplessness, and emotional overeating. The brain receptor molecules are key mediators of these processes, translating neuromodulatory signals into neuronal responses or circuit activity changes that ultimately shape behavioral outcomes. Here, I highlight several of my previous studies that reveal the pivotal role of receptor molecules in critical brain regions such as the nucleus accumbens, lateral hypothalamus, and lateral septum. I identified how mGluR5 signaling in the nucleus accumbens promotes stress resilience through pathways involving ΔFosB and SRF, while leptin receptor or glucocorticoid receptor signaling within lateral hypothalamic circuits contributes to stress eating. Additionally, I uncovered the role of dopamine receptor 3 signaling in the lateral septum in mediating the impact of early life stress on social behaviors. These findings underscore the functional relevance of brain receptor molecules in transducing stress-from early life through adulthood-into maladaptive coping behaviors. As druggable targets, these receptor-mediated pathways provide a critical foundation for developing targeted interventions to alleviate stress-related psychiatric symptoms.

YAP/TAZ Drive Agrin-Matrix Metalloproteinase 12-Mediated Diabetic Skin Wound Healing

Macroscopic loss of extracellular matrix can lead to chronic defects in skin wound healing, but supplementation of extracellular matrix holds promise for facilitating wound closure, particularly in diabetic wound healing. We recently showed that the extracellular matrix proteoglycan agrin accelerates cutaneous wound healing by improving mechanoperception of migrating keratinocytes and allowing them to respond to mechanical stresses through matrix metalloproteinase 12 (MMP12). RNA-sequencing analysis revealed that in addition to a disorganized extracellular matrix, agrin-depleted skin cells have impaired YAP/TAZ transcriptional outcomes, leading us to hypothesize that YAP/TAZ, as central mechanosensors, drive the functionality of agrin-MMP12 signaling during cutaneous wound repair. In this study, we demonstrate that agrin activates YAP/TAZ during migration of keratinocytes after wounding in vitro and in vivo. Mechanistically, YAP/TAZ sustain agrin and MMP12 protein expression during migration after wounding through positive feedback. YAP/TAZ silencing abolishes agrin-MMP12-mediated force recognition and geometrical constraints. Importantly, soluble agrin therapy accelerates wound closure in diabetic mouse models by engaging MMP12-YAP. Because patients with diabetic foot ulcers and impaired wound healing have reduced expression of agrin-MMP12 that correlates with YAP/TAZ inactivation, we propose that timely activation of YAP/TAZ by soluble agrin therapy can accentuate mechanobiological microenvironments for efficient wound healing, under normal and diabetic conditions.

Leptin deficiency leads to nerve degeneration and impairs axon remyelination by inducing Schwann cell apoptosis and demyelination in type 2 diabetic peripheral neuropathy in rats

Diabetic peripheral neuropathy, characterized by symptoms such as paresthesia, neuropathic pain, and potential lower limb amputation, poses significant clinical management challenges. Recent studies suggest that chronic hyperglycemia-induced Schwann cells (SCs) apoptosis contributes to neurodegeneration and impaired nerve regeneration, but the detailed mechanisms are still unknown. Our study investigated a mixed-sex type 2 diabetes mellitus (T2DM) rat model using leptin knockout (KO) to simulate obesity and diabetes-related conditions. Through extensive assessments, including mechanical allodynia, electrophysiology, and microcirculation analyses, along with myelin degradation studies in KO versus wild-type rats, we focused on apoptosis, autophagy, and SCs dedifferentiation in the sciatic nerve and examined nerve regeneration in KO rats. KO rats exhibited notable reductions in mechanical withdrawal force, prolonged latency, decreased compound muscle action potential (CMAP) amplitude, reduced microcirculation, myelin sheath damage, and increases in apoptosis, autophagy, and SCs dedifferentiation. Moreover, leptin KO was found to impair peripheral nerve regeneration postinjury, as indicated by reduced muscle weight, lower CMAP amplitude, extended latency, and decreased remyelination and SCs density. These findings underscore the effectiveness of the T2DM rat model in clarifying the impact of leptin KO on SCs apoptosis, dedifferentiation, and demyelination, providing valuable insights into new therapeutic avenues for treating T2DM-induced peripheral neuropathy.

Immune Dysregulation in Obesity

The immune system plays fundamental roles in maintaining physiological homeostasis. With the increasing prevalence of obesity-a state characterized by chronic inflammation and systemic dyshomeostasis-there is growing scientific and clinical interest in understanding how obesity reshapes immune function. In this review, we propose that obesity is not merely an altered metabolic state but also a fundamentally altered immunological state. We summarize key seminal and recent findings that elucidate how obesity influences immune function, spanning its classical role in microbial defense, its contribution to maladaptive inflammatory diseases such as asthma, and its impact on antitumor immunity. We also explore how obesity modulates immune function within tissue parenchyma, with a particular focus on the role of T cells in adipose tissue. Finally, we consider areas for future research, including investigation of the durable aspects of obesity on immunological function even after weight loss, such as those observed with glucagon-like peptide-1 (GLP-1) receptor agonist treatment. Altogether, this review emphasizes the critical role of systemic metabolism in shaping immune cell functions, with profound implications for tissue homeostasis across various physiological contexts.

Cholesterol restriction primes antiviral innate immunity via SREBP1-driven noncanonical type I IFNs

Cholesterol metabolism is associated with innate immune responses; however, the underlying mechanism remains unclear. Here, we perform chemical screening to isolate small molecules influencing RIG-I activity, a cytoplasmic viral RNA sensor. We find that statins, which inhibit cholesterol synthesis, dramatically enhance RIG-I-dependent antiviral responses in specific cell types. Since statins exhibit pleiotropic effects on type I interferon (IFN) responses, we further focus on their effects on RIG-I signaling. The restriction of cholesterol synthesis induces expression of noncanonical type I IFNs, such as IFN-ω, in an SREBP1 transcription factor-dependent manner. This pathway subsequently enhances RIG-I-mediated signaling following viral infection. Administration of statins augments RIG-I-dependent cytokine expression in the lungs of mice. Conversely, a mouse obesity model shows a diminished RIG-I response. Single-cell transcriptome analyses reveal a subset of alveolar macrophages that increase RIG-I expression in response to inhibited cholesterol synthesis in vivo. This study reveals SREBP1-mediated noncanonical type I IFN expression, linking cholesterol metabolism and RIG-I signaling.

Leptin/Melanocortin Pathway in Cholelithiasis Patients: A Diagnostic Perspective

BACKGROUND

Cholelithiasis is the most prevalent inflammatory condition of the gallbladder. The regulation of biological processes, including energy homeostasis, and control of body weight are key mechanisms that the leptin and melanocortin pathways play a role in Cholelithiasis is the most prevalent inflammatory condition of the gallbladder. There are various risk factors for the development of gallstone disease, especially weight gain, and obesity is just one of them. This risk factor can be minimized by maintaining appetite and energy balance. Here, leptin and melanocortin pathways are the key mechanisms in maintaining appetite and energy homeostasis.

OBJECTIVES

The aim of this study was to investigate the relationship between the levels of LEP, LEPR, TrkB, BDNF, POMC, and MC4R proteins in patients with Cholelithiasis. This study aims to determine the relationship between LEP, LEPR, TrkB, BDNF, POMC, and MC4R protein levels, which play a role in maintaining appetite and energy homeostasis, and cholelithiasis.

METHODS

This study examined 44 patients diagnosed with Cholelithiasis and 44 healthy control subjects who had not previously been diagnosed with any form of Cholelithiasis. The levels of leptin (LEP), Leptin Binds To Leptin Receptors (LEPR), Tropomyosin Receptor Kinase B (TrkB), Brain-Derived Neurotrophic Factor (BDNF), Pro-OpioMelanoCortin (POMC), and Melanocortin- 4 Receptors (MC4R) molecules were analyzed using the Enzyme-Linked Immunosorbent Assay (ELISA) method. The results were analyzed using the SPSS Software (Version 22.0) program and GraphPad Prism 8.0.1 software.

RESULTS

The study found a statistically significant decrease (p < 0.05) in MC4R, TrkB, BDNF, and POMC protein levels in Cholelithiasis patients compared to the control group. There was no statistically significant difference in LEP and LEPR concentration values between the two groups (p = 0.247, p = 0.674).

CONCLUSION

The proteins MC4R, TrkB, BDNF, and POMC, which are involved in the leptin and melanocortin pathways may play a significant role in Cholelithiasis disease. However, more detailed research on the relevant proteins is needed. Nevertheless, this research will guide new studies.

Understanding Adipose Tissue Dysfunction

Diseases affecting adipose tissue (AT) function include obesity, lipodystrophy, and lipedema, among others. Both a lack of and excess AT are associated with increased risk for developing diseases including type 2 diabetes mellitus, hypertension, obstructive sleep apnea, and some types of cancer. However, individual risk of developing cardiometabolic and other 'obesity-related' diseases is not entirely determined by fat mass. Rather than excess fat accumulation, AT dysfunction may represent the mechanistic link between obesity and comorbid diseases. There are people who remain metabolically healthy despite obesity, whereas people with normal weight or very low subcutaneous AT mass may develop typically obesity-related diseases. AT dysfunction is characterized by adipocyte hypertrophy, impaired subcutaneous AT expandability (ectopic fat deposition), hypoxia, a variety of stress, inflammatory processes, and the release of proinflammatory, diabetogenic, and atherogenic signals. Genetic and environmental factors might contribute to AT heterogeneity either alone or via interaction with intrinsic biological factors. However, many questions remain regarding the mechanisms of AT dysfunction initiation and whether and how it could be reversed. Do AT signatures define clinically relevant subtypes of obesity? Is the cellular composition of AT associated with variation in obesity phenotypes? What roles do environmental compounds play in the manifestation of AT dysfunction? Answers to these and other questions may explain AT disease mechanisms and help to define strategies for improving AT health. This review focuses on recent advances in our understanding of AT biology.

SGLT2 inhibition and adipose tissue metabolism: current outlook and perspectives

Sodium-glucose co-transporter 2 inhibitors (SGLT2i) have emerged as important agents for the treatment of type 2 diabetes mellitus (T2DM). SGLT2 inhibitors have been associated with improved cardiovascular outcomes, not only through their immediate hemodynamic effects-such as glycosuria and (at least temporary) increased natriuresis-but also due to their multifaceted impact on metabolism. Recently, studies have also focused on the effects of SGLT2 inhibitors on adipose tissue. Aside from the well-documented effects on human adiposity, SGLT2i have shown, both in vitro and in murine models, the ability to reduce fat mass, upregulate genes related to browning of white adipose tissue, influence adipocyte size and fatty acid oxidation, and improve oxidative stress and overall metabolic health. In humans, even though data are still limited, recent evidence seems to confirm that the SGLT2i effects observed in cardiovascular outcome trials could be partially explained by their impact on adipose tissue. This review aims to clarify the impact of SGLT2i on adipose tissue, highlighting their role in metabolic health and their potential to transform treatment strategies for T2DM beyond glucose metabolism.

Dietary Modulation of the Immune System

Recent insights into the influence of nutrition on immune system components have driven the development of dietary strategies targeting the prevention and management of major metabolic-inflammatory diseases. This review summarizes the bidirectional relationship between nutrition and immunocompetence, beginning with an overview of immune system components and their functions. It examines the effects of nutritional status, dietary patterns, and food bioactives on systemic inflammation, immune cell populations, and lymphoid tissues, as well as their associations with infectious and chronic disease pathogenesis. The mechanisms by which key nutrients influence immune constituents are delineated, focusing on vitamins A, D, E, C, and B, as well as minerals including zinc, iron, and selenium. Also highlighted are the immunomodulatory effects of polyunsaturated fatty acids as well as bioactive phenolic compounds and probiotics, given their expanding relevance. Each section addresses the implications of nutritional and nutraceutical interventions involving these nutrients within the broader context of major infectious, metabolic, and inflammatory diseases. This review further underscores that, while targeted nutrient supplementation can effectively restore immune function to optimal levels, caution is necessary in certain cases, as it may increase morbidity in specific diseases. In other instances, dietary counseling should be integrated to ensure that therapeutic goals are achieved safely and effectively.

Inflammatory mediator contributes to leptin resistance and obesity in craniopharyngioma

Obesity presents a significant challenge in managing patients with craniopharyngioma (CP). Cyst fluid (CF), rich in inflammatory mediators, is implicated in CP-related obesity, though the precise mechanism remains unclear. This study investigated the impact of CF or C-X-C motif chemokine ligand-1 (CXCL1) injections on body weight, Lee index, plasma lipid profiles, hepatic lipid accumulation, leptin levels, NF-κB pathway, the suppressor of cytokine signaling 3 (SOCS3) expression, and leptin sensitivity in rats. Bioinformatics was employed to identify differentially expressed genes (DEGs) between CF/CXCL1-treated and control SY5Y cells, as well as to confirm enriched pathways. Western blotting was used for experimental validation, including the effects of sodium salicylate (SS) on leptin sensitivity in SY5Y cells. Injecting CF or CXCL1 into the brain, without hypothalamic damage, led to increased body weight, Lee index, and hepatic lipid accumulation in rats, alongside elevated fasting blood glucose, triglycerides, and total cholesterol, while high-density lipoprotein cholesterol levels decreased. Additionally, CF and CXCL1 could induce elevated leptin levels, a higher leptin-to-body weight ratio, and resistance to exogenous leptin by activating the NF-κB pathway and upregulating the expression of SOCS3 in rats. Further validation confirmed that CF and CXCL1 suppress leptin signaling by activating the NF-κB pathway and upregulating SOCS3. Moreover, SS mitigated the inhibitory effects of CF or CXCL1 on leptin signaling, preserving leptin sensitivity in SY5Y cells. These results highlight the obesogenic role of CF and CXCL1, offering insights into the development of morbid obesity through inflammatory factor-mediated leptin resistance, independent of hypothalamic damage. SS may serve as a promising therapeutic approach for CP-associated obesity, though additional clinical studies are necessary to confirm its efficacy.

Cellular and molecular mechanisms underlying obesity in degenerative spine and joint diseases

Degenerative spine and joint diseases, including intervertebral disc degeneration (IDD), ossification of the spinal ligaments (OSL), and osteoarthritis (OA), are common musculoskeletal diseases that cause pain or disability to the patients. However, the pathogenesis of these musculoskeletal disorders is complex and has not been elucidated clearly to date. As a matter of fact, the spine and joints are not independent of other organs and tissues. Recently, accumulating evidence demonstrates the association between obesity and degenerative musculoskeletal diseases. Obesity is a common metabolic disease characterized by excessive adipose tissue or abnormal adipose distribution in the body. Excessive mechanical stress is regarded as a critical risk factor for obesity-related pathology. Additionally, obesity-related factors, mainly including lipid metabolism disorder, dysregulated pro-inflammatory adipokines and cytokines, are reported as plausible links between obesity and various human diseases. Importantly, these obesity-related factors are deeply involved in the regulation of cell phenotypes and cell fates, extracellular matrix (ECM) metabolism, and inflammation in the pathophysiological processes of degenerative spine and joint diseases. In this study, we systematically discuss the potential cellular and molecular mechanisms underlying obesity in these degenerative musculoskeletal diseases, and hope to provide novel insights for developing targeted therapeutic strategies.

Body Composition Changes and Factors Influencing the Total Weight Loss Rate After Laparoscopic Sleeve Gastrectomy

Objectives: While the effectiveness of metabolic/bariatric surgery has been confirmed, understanding the factors associated with weight loss is paramount for providing guidance in postoperative treatment strategies. Here, we aimed to examine the factors associated with long-term maintenance of weight loss after laparoscopic sleeve gastrectomy (LSG). Methods: This prospective observational cohort included patients who underwent LSG at a single academic health center between January 2017 and June 2022. We examined their body composition using InBody 720 or 770 and analyzed the factors associated with the percentage of total weight loss (%TWL) for 24 months. Results: The median body mass index (BMI) was 38.8 (interquartile range [IQR]: 35.6-46.7) preoperatively, 32.7 kg/m2 (IQR: 28.2-38.7) at 12 months postoperatively, and 33.9 kg/m2 (IQR: 29.1-40.1) at 24 months postoperatively. The lowest BMI was observed at 12 months (p < 0.001 vs. preoperative), followed by a significant increase at 24 months (p = 0.003). However, BMI remained significantly lower at 24 months than preoperatively (p < 0.001). The skeletal muscle mass to fat mass ratio (SMM/FM) was 0.59 (IQR: 0.50-0.71) preoperatively, 0.79 (IQR: 0.58-1.26) at 12 months, and 0.70 (IQR: 0.54-1.05) at 24 months, peaking at 12 months (p < 0.001 vs. preoperative) and decreasing significantly by 24 months (p < 0.001). Nevertheless, the SMM/FM ratio at 24 months remained higher than preoperative values (p < 0.001). Median body weight and %TWL were 86.0 kg and 15.6%, respectively, at 24 months after LSG. The SMM/FM ratio at 12 months was positively correlated with %TWL at 24 months after adjusting for age and sex. Conclusions: The effects of LSG persisted for up to 24 months postoperatively. The SMM/FM ratio 12 months after LSG was associated with the rate of weight loss at 24 months.

Can brain neurons change identity? Lessons from obesity

It has long been thought that the functional identity of mammalian brain neurons is programmed during development and remains stable throughout adult life; however, certain populations of neurons continue to express active regulators of neuronal identity into adulthood. Prolonged exposure to diet-induced metabolic stress induces features of neuronal identity modification in adult mice, and maladaptive changes in neuronal identity maintenance have been linked to cognitive impairment in humans suffering from neurodegenerative diseases often associated with obesity. Here we discuss how, by unraveling the neurological roots of obesity, we may solve the puzzle of whether mammalian brain neurons retain identity plasticity into adulthood, while advancing knowledge of the pathogenic mechanisms at the interface of metabolic and neurodegenerative disorders.

In vivo dynamics of hard tissue-forming cell origins: Insights from Cre/loxP-based cell lineage tracing studies

Bone tissue provides structural support for our bodies, with the inner bone marrow (BM) acting as a hematopoietic organ. Within the BM tissue, two types of stem cells play crucial roles: mesenchymal stem cells (MSCs) (or skeletal stem cells) and hematopoietic stem cells (HSCs). These stem cells are intricately connected, where BM-MSCs give rise to bone-forming osteoblasts and serve as essential components in the BM microenvironment for sustaining HSCs. Despite the mid-20th century proposal of BM-MSCs, their in vivo identification remained elusive owing to a lack of tools for analyzing stemness, specifically self-renewal and multipotency. To address this challenge, Cre/loxP-based cell lineage tracing analyses are being employed. This technology facilitated the in vivo labeling of specific cells, enabling the tracking of their lineage, determining their stemness, and providing a deeper understanding of the in vivo dynamics governing stem cell populations responsible for maintaining hard tissues. This review delves into cell lineage tracing studies conducted using commonly employed genetically modified mice expressing Cre under the influence of LepR, Gli1, and Axin2 genes. These studies focus on research fields spanning long bones and oral/maxillofacial hard tissues, offering insights into the in vivo dynamics of stem cell populations crucial for hard tissue homeostasis.

A subcortical feeding circuit linking an interoceptive node to jaw movement

The brain processes an array of stimuli, enabling the selection of appropriate behavioural responses, but the neural pathways linking interoceptive inputs to outputs for feeding are poorly understood1-3. Here we delineate a subcortical circuit in which brain-derived neurotrophic factor (BDNF)-expressing neurons in the ventromedial hypothalamus (VMH) directly connect interoceptive inputs to motor centres, controlling food consumption and jaw movements. VMHBDNF neuron inhibition increases food intake by gating motor sequences of feeding through projections to premotor areas of the jaw. When food is unavailable, VMHBDNF inhibition elicits consummatory behaviours directed at inanimate objects such as wooden blocks, and inhibition of perimesencephalic trigeminal area (pMe5) projections evokes rhythmic jaw movements. The activity of these neurons is decreased during food consumption and increases when food is in proximity but not consumed. Activity is also increased in obese animals and after leptin treatment. VMHBDNF neurons receive monosynaptic inputs from both agouti-related peptide (AgRP) and proopiomelanocortin neurons in the arcuate nucleus (Arc), and constitutive VMHBDNF activation blocks the orexigenic effect of AgRP activation. These data indicate an Arc → VMHBDNF → pMe5 circuit that senses the energy state of an animal and regulates consummatory behaviours in a state-dependent manner.

Interplay between the brain and adipose tissue: a metabolic conversation

The central nervous system and adipose tissue interact through complex communication. This bidirectional signaling regulates metabolic functions. The hypothalamus, a key homeostatic brain region, integrates exteroceptive and interoceptive signals to control appetite, energy expenditure, glucose, and lipid metabolism. This regulation is partly achieved via the nervous modulation of white (WAT) and brown (BAT) adipose tissue. In this review, we highlight the roles of sympathetic and parasympathetic innervation in regulating WAT and BAT activities, such as lipolysis and thermogenesis. Adipose tissue, in turn, plays a dual role as an energy reservoir and an endocrine organ, secreting hormones that influence brain function and metabolic health. In addition, this review focuses on recently uncovered communication pathways, including extracellular vesicles and neuro-mesenchymal units, which add new layers of regulation and complexity to the brain-adipose tissue interaction. Finally, we also examine the consequences of disrupted communication between the brain and adipose tissue in metabolic disorders like obesity and type-2 diabetes, emphasizing the potential for new therapeutic strategies targeting these pathways to improve metabolic health.

Increased cancellous bone mass accompanies decreased cortical bone mineral density and higher axial deformation in femurs of leptin-deficient obese mice

INTRODUCTION

Leptin is a pleiotropic hormone that regulates food intake and energy homeostasis with enigmatic effects on bone development. It is unclear if leptin promotes or inhibits bone growth. The aim of this study was to characterize the micro-architecture and mechanical competence of femur bones of leptin-deficient mice.

MATERIALS AND METHODS

Right femur bones of 15-week old C57BL/6 (n = 9) and leptin-deficient (ob/ob, n = 9) mice were analyzed. Whole bones were scanned using micro-CT and morphometric parameters of the cortex and trabeculae were assessed. Elastic moduli were determined from microindentations in midshaft cross-sections. Mineral densities were determined using quantitative backscatter scanning electron microscopy. 3D models of the distal femur metaphysis, cleared from trabecular bone, were meshed and used for finite element simulations of axial loading to identify straining differences between ob/ob and C57BL/6 controls.

RESULTS

Compared with C57BL/6 controls, ob/ob mice had significantly shorter bones. ob/ob mice showed significantly increased cancellous bone volume and trabecular thickness. qBEI quantified a ∼7% lower mineral density in ob/ob mice in the distal femur metaphysis. Indentation demonstrated a significantly reduced Young's modulus of 12.14 [9.67, 16.56 IQR] GPa for ob/ob mice compared to 23.12 [20.70, 26.57 IQR] GPa in C57BL/6 mice. FEA revealed greater deformation of cortical bone in ob/ob as compared to C57BL/6 mice.

CONCLUSION

Leptin deficient ob/ob mice have a softer cortical bone in the distal femur metaphysis but an excessive amount of cancellous bone, possibly as a response to increased deformation of the bones during axial loading. Both FEA and direct X-ray and electron microscopy imaging suggest that the morphology and micro-architecture of ob/ob mice have inferior biomechanical properties suggestive of a reduced mechanical competence.

Regulatory role of Heparan sulfate in leptin signaling

Leptin, a hormone mainly secreted by adipocytes, has attracted significant attention since its discovery in 1994. Initially known for its role in appetite suppression and energy regulation, leptin is now recognized for its influence on various physiological processes, including immune response, bone formation, and reproduction. It exerts its effects by binding to receptors and initiating an intracellular signaling cascade. Heparan sulfate (HS) is known to regulate the intracellular signaling of various ligands. HS is present as the glycan portion of HSPGs on cell surfaces and in intercellular spaces, with diverse structures due to extensive sulfation and epimerization. Although HS chains on HSPGs are involved in many physiological processes, the detailed effects of HS chains on leptin signaling are not well understood. This study examined the role of HS chains on HSPGs in leptin signaling using Neuro2A cells expressing the full-length leptin receptor (LepR). We showed that cell surface HS was essential for efficient leptin signaling. Enzymatic degradation of HS significantly reduced leptin-induced phosphorylation of downstream molecules, such as signal transducer and activator of transcription 3 and p44/p42 Mitogen-activated protein kinase. In addition, HS regulated LepR expression and internalization, as treatment with HS-degrading enzymes decreased cell surface LepR. HS was also found to exhibit a weak interaction with LepR. Enzymatic removal of HS enhanced the interaction between LepR and low-density lipoprotein receptor-related protein 1, suggesting that HS negatively regulates this interaction. In conclusion, HS plays a significant role in modulating LepR availability on the cell surface, thereby influencing leptin signaling. These findings provide new insights into the complex regulation of leptin signaling and highlight potential therapeutic targets for metabolic disorders and obesity.

Leptin-activated hypothalamic BNC2 neurons acutely suppress food intake

Leptin is an adipose tissue hormone that maintains homeostatic control of adipose tissue mass by regulating the activity of specific neural populations controlling appetite and metabolism1. Leptin regulates food intake by inhibiting orexigenic agouti-related protein (AGRP) neurons and activating anorexigenic pro-opiomelanocortin (POMC) neurons2. However, whereas AGRP neurons regulate food intake on a rapid time scale, acute activation of POMC neurons has only a minimal effect3-5. This has raised the possibility that there is a heretofore unidentified leptin-regulated neural population that rapidly suppresses appetite. Here we report the discovery of a new population of leptin-target neurons expressing basonuclin 2 (Bnc2) in the arcuate nucleus that acutely suppress appetite by directly inhibiting AGRP neurons. Opposite to the effect of AGRP activation, BNC2 neuronal activation elicited a place preference indicative of positive valence in hungry but not fed mice. The activity of BNC2 neurons is modulated by leptin, sensory food cues and nutritional status. Finally, deleting leptin receptors in BNC2 neurons caused marked hyperphagia and obesity, similar to that observed in a leptin receptor knockout in AGRP neurons. These data indicate that BNC2-expressing neurons are a key component of the neural circuit that maintains energy balance, thus filling an important gap in our understanding of the regulation of food intake and leptin action.

Evidence from clinical studies of leptin: current and future clinical applications in humans

Leptin has been established as the prototype adipose tissue secreted hormone and as a major regulator of several human physiology functions. Here, we are primarily reviewing the findings from studies in humans involving leptin administration. We are describing the metabolic, endocrine and immunologic effects of leptin replacement in conditions of leptin deficiency, such as short-term fasting in healthy individuals, relative energy deficiency in sports (REDS), congenital leptin deficiency (CLD), generalized (GL) and partial lipodystrophy (PL), HIV-associated lipodystrophy (HIV-L) and of leptin treatment in conditions of leptin excess (common obesity, type 2 diabetes, steatotic liver disease). We are comparing the results with the findings from preclinical models and present the main conclusions regarding the role of leptin in human physiology, pathophysiology and therapeutics. We conclude that, in conditions of energy deficiency, leptin substitution effectively reduces body weight and fat mass through reduction of appetite, it improves hypertriglyceridemia, insulin resistance and hepatic steatosis (especially in GL and PL), it restores neuroendocrine function (especially the gonadotropic axis), it regulates adaptive immune system cell populations and it improves bone health. On the contrary, leptin treatment in conditions of leptin excess, such as common obesity and type 2 diabetes, does not improve any metabolic abnormalities. Strategies to overcome leptin tolerance/resistance in obesity and type 2 diabetes have provided promising results in animal studies, which should though be tested in humans in randomized clinical trials.

History and future of leptin: Discovery, regulation and signaling

The cloning of leptin 30 years ago in 1994 was an important milestone in obesity research. Prior to the discovery of leptin, obesity was stigmatized as a condition caused by lack of character and self-control. Mutations in either leptin or its receptor were the first single gene mutations found to cause severe obesity, and it is now recognized that obesity is caused mostly by a dysregulation of central neuronal circuits. Since the discovery of the leptin-deficient obese mouse (ob/ob) the cloning of leptin (ob aka lep) and leptin receptor (db aka lepr) genes, we have learned much about leptin and its action in the central nervous system. The first hope that leptin would cure obesity was quickly dampened because humans with obesity have increased leptin levels and develop leptin resistance. Nevertheless, leptin target sites in the brain represent an excellent blueprint to understand how neuronal circuits control energy homeostasis. Our expanding understanding of leptin function, interconnection of leptin signaling with other systems and impact on distinct physiological functions continues to guide and improve the development of safe and effective interventions to treat metabolic illnesses. This review highlights past concepts and current emerging concepts of the hormone leptin, leptin receptor signaling pathways and central targets to mediate distinct physiological functions.

Association between metabolic syndrome and benign prostatic hyperplasia: The underlying molecular connection

Benign prostatic hyperplasia (BPH), a common cause of lower urinary tract symptoms (LUTS), has been recently regarded as a metabolic disease. Metabolic syndrome (MetS) is a constellation of metabolic disarrangements, including insulin resistance, obesity, hypertension, and dyslipidemia, and it has been established that these components of MetS are important contributing factors exacerbating the degree of prostatic enlargement and bladder outlet obstruction among patients with BPH. Clinical and experimental studies demonstrated that many molecules, such as insulin, insulin-like growth factor 1 (IGF-1), androgen and estrogen, and adipokines, are involved in the overlapping pathogenesis of BPH and MetS, indicating that clinicians might be able to simultaneously alleviate or cure two diseases by choosing appropriate medications. This article aims to systematically review the pathophysiological aspect and traditional etiology and pathogenesis of BPH and discuss the intricate association between MetS and BPH from the molecular point of view, in an attempt to provide stronger evidence for better treatment of two diseases.

Leptin physiology and pathophysiology in energy homeostasis, immune function, neuroendocrine regulation and bone health

Since its discovery and over the past thirty years, extensive research has significantly expanded our understanding of leptin and its diverse roles in human physiology, pathophysiology and therapeutics. A prototypical adipokine initially identified for its critical function in appetite regulation and energy homeostasis, leptin has been revealed to also exert profound effects on the hypothalamic-pituitary-gonadal, thyroid, adrenal and growth hormone axis, differentially between animals and humans, as well as in regulating immune function. Beyond these roles, leptin plays a pivotal role in significantly affecting bone health by promoting bone formation and regulating bone metabolism both directly and indirectly through its neuroendocrine actions. The diverse actions of leptin are particularly notable in leptin-deficient animal models and in conditions characterized by low circulating leptin levels, such as lipodystrophies and relative energy deficiency. Conversely, the effectiveness of leptin is attenuated in leptin-sufficient states, such as obesity and other high-adiposity conditions associated with hyperleptinemia and leptin tolerance. This review attempts to consolidate 30 years of leptin research with an emphasis on its physiology and pathophysiology in humans, including its promising therapeutic potential. We discuss preclinical and human studies describing the pathophysiology of energy deficiency across organ systems and the significant role of leptin in regulating neuroendocrine, immune, reproductive and bone health. We finally present past proof of concept clinical trials of leptin administration in leptin-deficient subjects that have demonstrated positive neuroendocrine, reproductive, and bone health outcomes, setting the stage for future phase IIb and III randomized clinical trials in these conditions.

Postnatal surge of adipose-secreted leptin is a robust predictor of fat mass trajectory in mice

The transient postnatal increase in circulating leptin levels, known as leptin surge, may increase later susceptibility to diet-induced obesity in rodents. However, the source of leptin during the surge needs to be better characterized, and the long-term effects of leptin are contradictory. Characterization of the interaction of leptin with the genetic background, sex, and other factors is required. Here, we focused on the impact of circulating leptin levels and several related variables, measured in 2- and 4-wk-old i) obesity-prone C57BL/6 (B6) and ii) obesity-resistant A/J mice. In total, 264 mice of both sexes were used. Posttranscriptionally controlled leptin secretion from subcutaneous white adipose tissue, the largest adipose tissue depot in mice pups, was the primary determinant of plasma leptin levels. When the animals were randomly assigned standard chow or high-fat diet (HFD) between 12 and 24 wk of age, the obesogenic effect of HFD feeding was observed in B6 but not A/J mice. Only leptin levels at 2 wk, i.e., close to the maximum in the postnatal leptin surge, correlated with both body weight (BW) trajectory throughout the life and adiposity of the 24-wk-old mice. Leptin surge explained 13 and 7% of the variance in BW and adiposity of B6 mice, and 9 and 35% of the variance in these parameters in A/J mice, with a minor role of sex. Our results prove the positive correlation between the leptin surge and adiposity in adulthood, reflecting the fundamental biological role of leptin. This role could be compromised in subjects with obesity.NEW & NOTEWORTHY The postnatal surge in circulating leptin levels in mice reflects particularly posttranscriptionally controlled release of this hormone from subcutaneous white adipose tissue. Leptinemia in 2-wk-old pups predicts both body weight and adiposity in adult mice fed a high-fat diet. The extent of these effects depends on genetically determined differences in propensity to obesity between C57BL/6 and A/J mice. The leptin effect on adiposity is compromised in the obesity-prone C57BL/6 mice.

Brown and beige adipose tissue-derived metabokine and lipokine inter-organ signalling in health and disease

Adipose tissue has an established endocrine function through the secretion of adipokines. However, a role for bioactive metabolites and lipids, termed metabokines and lipokines, is emerging in adipose tissue-mediated autocrine, paracrine and endocrine signalling and inter-organ communication. Traditionally seen as passive entities, metabolites are now recognized for their active roles in regulating cellular signalling and local and systemic metabolism. Distinct from white adipose tissue, specific endocrine functions have been attributed to thermogenic brown and beige adipose tissues. Brown and beige adipose tissues have been identified as sources of metabokines and lipokines, which influence diverse metabolic pathways, such as fatty acid β-oxidation, mitochondrial function and glucose homeostasis, across a range of tissues, including skeletal muscle, adipose tissue and heart. This review explores the intricate signalling mechanisms of brown and beige adipose tissue-derived metabokines and lipokines, emphasizing their roles in maintaining metabolic homeostasis and their potential dysregulation in metabolic diseases. Furthermore, we discuss the therapeutic potential of targeting these pathways, proposing that precise modulation of metabokine receptors and transporters could offer superior specificity and efficacy in comparison to conventional approaches, such as β-adrenergic signalling-stimulated activation of brown adipose tissue thermogenesis. Understanding the complex interactions between adipokines, metabokines and lipokines is essential for developing a systems-level approach to new interventions for metabolic disorders, underscoring the need for continued research in this rapidly evolving field.

Adipokines and their potential impacts on susceptibility to myocardial ischemia/reperfusion injury in diabetes

Coronary artery disease has a high mortality rate and is a striking public health concern, affecting a substantial portion of the global population. On the early onset of myocardial ischemia, thrombolytic therapy and coronary revascularization could promptly restore the bloodstream and nutrient supply to the ischemic tissue, efficiently preserving less severely injured myocardium. However, the abrupt re-establishment of blood flow triggers the significant discharge of previously accumulated oxidative substances and inflammatory cytokines, leading to further harm referred to as ischemia/reperfusion (I/R) injury. Diabetes significantly raises the vulnerability of the heart to I/R injury due to disrupted glucose and lipid processing, impaired insulin sensitivity and metabolic signaling, and increased inflammatory responses. Numerous studies have indicated that adipokines are crucial in the etiology and pathogenesis of obesity, diabetes, hyperlipidemia, hypertension, and coronary artery disease. Adipokines such as adiponectin, adipsin, visfatin, chemerin, omentin, and apelin, which possess protective properties against inflammatory activity and insulin resistance, have been shown to confer myocardial protection in conditions such as atherosclerosis, myocardial hypertrophy, myocardial I/R injury, and diabetic complications. On the other hand, adipokines such as leptin and resistin, known for their pro-inflammatory characteristics, have been linked to elevated cardiac lipid deposition, insulin resistance, and fibrosis. Meteorin-like (metrnl) exhibits opposite effects in various pathological conditions. However, the data on adipokines in myocardial I/R, especially in diabetes, is still incomplete and controversial. This review focuses on recent research regarding the categorization and function of adipokines in the heart muscle, and the identification of different signaling pathways involved in myocardial I/R injury under diabetic conditions, aiming to facilitate the exploration of therapeutic strategies against myocardial I/R injury in diabetes.

Mechanisms by which obesity regulates inflammation and anti-tumor immunity in cancer

Obesity is associated with an increased risk for 13 different cancers. The increased risk for cancer in obesity is mediated by obesity-associated changes in the immune system. Obesity has distinct effects on different types of inflammation that are tied to tumorigenesis. For example, obesity promotes chronic inflammation in adipose tissue that is tumor-promoting in peripheral tissues. Conversely, obesity inhibits acute inflammation that rejects tumors. Obesity therefore promotes cancer by differentially regulating chronic versus acute inflammation. Given that obesity is chronic, the initial inflammation in adipose tissue will lead to systemic inflammation that could induce compensatory anti-inflammatory reactions in peripheral tissues to suppress chronic inflammation. The overall effect of obesity in peripheral tissues is therefore dependent on the duration and severity of obesity. Adipose tissue is a complex tissue that is composed of many cell types in addition to adipocytes. Further, adipose tissue cellularity is different at different anatomical sites throughout the body. Consequently, the sensitivity of adipose tissue to obesity is dependent on the anatomical location of the adipose depot. For example, obesity induces more inflammation in visceral than subcutaneous adipose tissue. Based on these studies, the mechanisms by which obesity promotes tumorigenesis are multifactorial and immune cell type-specific. The objective of our paper is to discuss the cellular mechanisms by which obesity promotes tumorigenesis by regulating distinct types of inflammation in adipose tissue and the tumor microenvironment.

The role of macrophage and adipocyte mitochondrial dysfunction in the pathogenesis of obesity

Obesity has emerged as a prominent global public health concern, leading to the development of numerous metabolic disorders such as cardiovascular diseases, type-2 diabetes mellitus (T2DM), sleep apnea and several system diseases. It is widely recognized that obesity is characterized by a state of inflammation, with immune cells-particularly macrophages-playing a significant role in its pathogenesis through the production of inflammatory cytokines and activation of corresponding pathways. In addition to their immune functions, macrophages have also been implicated in lipogenesis. Additionally, the mitochondrial disorders existed in macrophages commonly, leading to decreased heat production. Meantime, adipocytes have mitochondrial dysfunction and damage which affect thermogenesis and insulin resistance. Therefore, enhancing our comprehension of the role of macrophages and mitochondrial dysfunction in both macrophages and adipose tissue will facilitate the identification of potential therapeutic targets for addressing this condition.

The hypothalamus as the central regulator of energy balance and its impact on current and future obesity treatments

The hypothalamus is a master regulator of energy balance in the body. First-order hypothalamic neurons localized in the arcuate nucleus sense systemic signals that indicate the energy stores in the body. Through distinct projections, arcuate nucleus neurons communicate with second-order neurons, which are mostly localized in the paraventricular nucleus and in the lateral hypothalamus. The signals then proceed to third- and fourth-order neurons that activate complex responses aimed at maintaining whole-body energy homeostasis. During the last 30 years, since the identification of leptin in 1994, there has been a great advance in the unveiling of the hypothalamic and extra-hypothalamic neuronal networks that control energy balance. This has contributed to the characterization of the mechanisms by which glucagon-like peptide-1 receptor agonists promote body mass reduction and has opened new windows of opportunity for the development of drugs to treat obesity. This review presents an overview of the mechanisms involved in the hypothalamic regulation of energy balance and discusses how advancements in this field are contributing to the development of new pharmacological strategies to treat obesity.

Leptin A deficiency affecting the mitochondrial dynamics of aged oocytes in medaka (Oryzias latipes)

Mitochondrial dysfunction and metabolic disorder have been associated to age-related subfertility, however, the precise molecular mechanism controlling the development of fertile oocytes in aging females remains elusive. Leptin plays an important role in the maintenance of energy homeostasis, as both excessive or insufficient levels can affect the body weight and fertility of mice. Here, we report that leptin A deficiency affects growth and shortens reproductive lifespan by reducing fertility in medaka (Oryzias latipes). Targeted disruption of lepa (lepa-/-) females reduced their egg laying and fertility compared to normal 3-month-old females (lepa+/+ sexual maturity), with symptoms worsening progressively at the age of 6 months and beyond. Transcriptomic analysis showed that differentially expressed genes involved in metabolic and mitochondrial pathways were significantly altered in lepa-/- ovaries compared with the normal ovaries at over 6 months old. The expression levels of the autophagy-promoting genes ulk1a, atg7 and atg12 were significantly differentiated between normal and lepa-/- ovaries, which were further confirmed by quantitative polymerase chain reaction analysis, indicating abnormal autophagy activation and mitochondrial dysfunction in oocyte development lacking lepa. Transmission electron microscopy observations further confirmed these mitochondrial disorders in lepa-deficient oocytes. In summary, these research findings provide novel insights into how leptin influences female fertility through mitochondrial-mediated oocyte development.

Rare variant analyses in 51,256 type 2 diabetes cases and 370,487 controls reveal the pathogenicity spectrum of monogenic diabetes genes

Type 2 diabetes (T2D) genome-wide association studies (GWASs) often overlook rare variants as a result of previous imputation panels' limitations and scarce whole-genome sequencing (WGS) data. We used TOPMed imputation and WGS to conduct the largest T2D GWAS meta-analysis involving 51,256 cases of T2D and 370,487 controls, targeting variants with a minor allele frequency as low as 5 × 10-5. We identified 12 new variants, including a rare African/African American-enriched enhancer variant near the LEP gene (rs147287548), associated with fourfold increased T2D risk. We also identified a rare missense variant in HNF4A (p.Arg114Trp), associated with eightfold increased T2D risk, previously reported in maturity-onset diabetes of the young with reduced penetrance, but observed here in a T2D GWAS. We further leveraged these data to analyze 1,634 ClinVar variants in 22 genes related to monogenic diabetes, identifying two additional rare variants in HNF1A and GCK associated with fivefold and eightfold increased T2D risk, respectively, the effects of which were modified by the individual's polygenic risk score. For 21% of the variants with conflicting interpretations or uncertain significance in ClinVar, we provided support of being benign based on their lack of association with T2D. Our work provides a framework for using rare variant GWASs to identify large-effect variants and assess variant pathogenicity in monogenic diabetes genes.

Cue-potentiated feeding in rodents: Implications for weight regulation in obesogenic environments

Cue-potentiated feeding (CPF) describes instances where food intake is increased by exposure to conditioned cues associated with food, often in the absence of hunger. CPF effects have been reported in a range of experimental protocols developed by researchers working across diverse fields spanning behavioural neuroscience, social psychology and ecology. Here we review the evolution of research on cue-potentiated feeding in animal models to identify important behavioural parameters and key neural circuits and pharmacological systems underlying the effect. Overall, evidence indicates that social, discrete and contextual stimuli can be used to elicit CPF effects across multiple species, though effects are often subtle and sensitive to procedural variables. While regular exposure to food cues is thought to be a key risk factor for overeating in so-called 'obesogenic' environments, further work is needed to identify whether CPF promotes positive energy balance and weight gain over the longer term. We suggest several methodological and conceptual areas for inquiry to elucidate the contribution of CPF to the regulation of food choice and energy intake.

From Mammals to Insects: Exploring the Genetic and Neural Basis of Eating Behavior

Obesity and anorexia are life-threatening diseases that are still poorly understood at the genetic and neuronal levels. Patients suffering from these conditions experience disrupted regulation of food consumption, leading to extreme weight gain or loss and, in severe situations, death from metabolic dysfunction. Despite the development of various behavioral and pharmacological interventions, current treatments often yield limited and short-lived success. To address this, a deeper understanding of the genetic and neural mechanisms underlying food perception and appetite regulation is essential for identifying new drug targets and developing more effective treatment methods. This review summarizes the progress of past research in understanding the genetic and neural mechanisms controlling food consumption and appetite regulation, focusing on two key model organisms: the fruit fly Drosophila melanogaster and the mouse Mus musculus. These studies investigate how the brain senses energy and nutrient deficiency, how sensory signals trigger appetitive behaviors, and how food intake is regulated through interconnected neural circuits in the brain.