Angiocrine polyamine production regulates adiposity

CD14loCD301b+ macrophages gathering as a proangiogenic marker in adipose tissues

The role of the monocyte marker CD14 in the regulation of obesity is increasingly recognized. Our observations indicated that Cd14-/- mice exhibited a leaner body shape compared to their wild type (WT) counterparts. And the loss of CD14 alleviated high-fat diet (HFD)-induced obesity in mice. In human subjects, CD14 level was tested to be positively correlated with overweight and obesity. However, the relationship between CD14 and the development of obesity remains only partially understood. To investigate the underlying mechanisms, adipose tissues (AT) from Cd14-/- and WT mice were subjected to deep RNA sequencing. Gene Ontology enrichment analysis revealed a significant enhancement of angiogenesis-related function in the Cd14-/- epWAT compared to WT counterpart, which was accompanied by an upregulation of Cd301b. Subsequent assays confirmed the enhanced angiogenesis and more accumulation of CD301b+ macrophages in Cd14-/- epWAT. Because Igf1 expression has been suggested to be associated with Cd301b expression through pseudotime analysis, we found it was IGF-1 secreted from Cd14-/- macrophages that mediated the angiogenesis enhancement. Collectively, our findings indicate that the accumulation of CD14loCD301b+ macrophages may serve as a proangiogenic marker in adipose tissues, providing novel insights into the relationship between CD14 and obesity development.

Exercise-regulated lipolysis: Its role and mechanism in health and diseases

Exercise has received considerable attention because of its importance not just in regulating physiological function, but also in ameliorating multiple pathological processes. Among these processes, lipolysis may play an important role in exercise-induced benefits. It is generally accepted that active lipolysis contributes to breakdown of fats, leading to the release of free fatty acids (FFAs) that serve as an energy source for muscles and other tissues during exercise. However, the significance of lipolysis in the context of exercise has not been fully understood. This review comprehensively outlines the potential regulatory mechanisms by which exercise stimulates lipolysis. The potential roles of exercise-mediated lipolysis in various physiological and pathological processes are also summarized. Additionally, we also discussed the potential non-classical effects of key lipolytic effectors induced by exercise. This will enhance our understanding of how exercise improves lipolytic function to bring about beneficial effects, offering new insights into potential therapeutic avenues for promoting health and alleviating diseases.

Polyamine metabolism in macrophage-adipose tissue function and homeostasis

Intracellular metabolism is a crucial regulator of macrophage function. Recent evidence revealed that the polyamine pathway and subsequent hypusination of eukaryotic initiation factor 5A (eIF5A) are master regulators of immune cell functions. In brown adipose tissue (BAT), macrophages show an impressive degree of heterogenicity, with specific subsets supporting adaptive thermogenesis during cold exposure. In this review, we discuss the impact of polyamine metabolism on macrophage diversity and function, with a particular focus on their role in adipose tissue homeostasis. Thus, we highlight the exploration of how polyamine metabolism in macrophages contributes to BAT homeostasis as an attractive and exciting new field of research.

Metabolic adaptations in prostate cancer

Prostate cancer is one of the most commonly diagnosed cancers in men and is a major cause of cancer-related deaths worldwide. Among the molecular processes that contribute to this disease, the weight of metabolism has been placed under the limelight in recent years. Tumours exhibit metabolic adaptations to comply with their biosynthetic needs. However, metabolites also play an important role in supporting cell survival in challenging environments or remodelling the tumour microenvironment, thus being recognized as a hallmark in cancer. Prostate cancer is uniquely driven by androgen receptor signalling, and this knowledge has also influenced the paths of cancer metabolism research. This review provides a comprehensive perspective on the metabolic adaptations that support prostate cancer progression beyond androgen signalling, with a particular focus on tumour cell intrinsic and extrinsic pathways.

Obesity alters adipose tissue response to fasting and refeeding in women: A study on lipolytic and endocrine dynamics and acute insulin resistance

Fasting induces significant shifts in substrate utilization with signs of acute insulin resistance (IR), while obesity is associated with chronic IR. Nonetheless, both states substantially influence adipose tissue (AT) function. Therefore, in this interventional study (NCT04260542), we investigated if excessive adiposity in premenopausal women alters insulin sensitivity and AT metabolic and endocrine activity in response to a 60-h fast and a subsequent 48-h refeeding period. Using physiological methods, lipidomics, and AT explants, we showed that obesity partially modified AT endocrine activity and blunted the dynamics of AT insulin resistance in response to the fasting/refeeding challenge compared to that observed in lean women. AT adapted to its own excess by reducing lipolytic activity/free fatty acids (FFA) flux per mass. This adaptation persisted even after a 60-h fast, resulting in lower ketosis in women with obesity. This could be a protective mechanism that limits the lipotoxic effects of FFA; however, it may ultimately impede desirable weight loss induced by caloric restriction in women with obesity.

A systems view of the vascular endothelium in health and disease

The dysfunction of blood-vessel-lining endothelial cells is a major cause of mortality. Although endothelial cells, being present in all organs as a single-cell layer, are often conceived as a rather inert cell population, the vascular endothelium as a whole should be considered a highly dynamic and interactive systemically disseminated organ. We present here a holistic view of the field of vascular research and review the diverse functions of blood-vessel-lining endothelial cells during the life cycle of the vasculature, namely responsive and relaying functions of the vascular endothelium and the responsive roles as instructive gatekeepers of organ function. Emerging translational perspectives in regenerative medicine, preventive medicine, and aging research are developed. Collectively, this review is aimed at promoting disciplinary coherence in the field of angioscience for a broader appreciation of the importance of the vasculature for organ function, systemic health, and healthy aging.

Enhanced lipid metabolism reprogramming in CHF rats through IL-6-mediated cardiac glial cell modulation by digilanid C and electroacupuncture stimulation combination

Background

Cardiac lipid metabolism reprogramming is recognized as a critical pathological factor in the progression of chronic heart failure (CHF). The therapeutic potential of digilanid C and electroacupuncture stimulation (ES) in enhancing lipid metabolism and cardiac function has been established. However, the optimal synergistic regulatory strategies of these interventions on cardiac lipid metabolism have yet to be elucidated.

Methods

This study aimed to comprehensively evaluate the impact of a digilanid C-ES combination on cardiac steatosis remodeling in CHF. Assessments were conducted across various dimensions, including myocardial oxygen consumption, mitochondrial function, and lipid metabolism. Additionally, we sought to uncover the underlying neuromolecular mechanisms.

Results

Our findings, at both molecular and morphological levels, indicated that the synergistic application of digilanid C and ES significantly inhibited myocardial fibrosis and steatosis. This combination therapy facilitated the repair of cardiac neuro-vascular uncoupling and induced a reprogramming of lipid metabolism. Notably, the digilanid C-ES combination ameliorated cardiomyocyte apoptosis and enhanced mitochondrial biogenesis in CHF, leading to a restructured energy supply pattern. Cardiac immunofluorescence analyses revealed the aggregation of cardiac glial cells (CGCs) at sites of abnormal neurovascular coupling, a response to cardiac lipid degeneration. This was accompanied by a marked reduction in the abnormally elevated expression of interleukin 6 (IL-6) and glutamatergic signaling, which correlated with the severity of cardiac steatosis and the aberrant activation of CGCs. The combined therapy was found to activate the Janus kinase 1 (JAK1)/signal transducer and activator of transcription 3 (STAT3) pathway, effectively attenuated lipid accumulation and over-recruitment of CGCs and deprivation of glutamatergic nerves.

Conclusion

These findings underscore the potential of digilanid C and ES combination therapy as a novel approach to modulate the complex interplay between neurovascular dynamics and metabolic dysregulation in CHF.

Gastrodin alleviates the deterioration of depressive-like behavior and glucolipid metabolism promoted by chronic stress in type 2 diabetic mice

The growing burden of psychological stress among diabetes patients has contributed to a rising incidence of depression within this population. It is of significant importance to conduct research on the impact of stress on diabetes patients and to explore potential pharmacological interventions to counteract the stress-induced exacerbation of their condition. Gastrodin is a low molecular weight bioactive compound extracted from the rhizome of Gastrodiae elata Blume, and it may be a preventive strategy for diabetes and a novel treatment for depression symptoms. However, its relevant pharmacological mechanisms for protecting against the impacts of psychological stress in diabetic patients are unclear. In this study, we performed 5 weeks CUMS intervention and simultaneously administered gastrodin (140 mg/kg, once daily) on T2DM mice, to investigate the potential protective effects of gastrodin. The protective effect of gastrodin was evaluated by behavioral tests, biochemical analysis, histopathological examination, RT-qPCR and gut microbiota analysis. We found that the depressive-like behavior and glucolipid metabolism could be deteriorated by chronic stress in type 2 diabetic mice, while gastrodin showed a protective effect against these exacerbations by regulating HPA hormones, activating FXR and Cyp7a1, reducing inflammatory and oxidative stress responses, and regulating ileal gut microbiota abundance. Gastrodin might be a potential therapeutic agent for mitigating the deterioration of diabetes conditions due to chronic stress.

Impaired polyamine metabolism causes behavioral and neuroanatomical defects in a mouse model of Snyder-Robinson syndrome

Snyder-Robinson syndrome (SRS) is a rare X-linked recessive disorder caused by a mutation in the SMS gene, which encodes spermine synthase, and aberrant polyamine metabolism. SRS is characterized by intellectual disability, thin habitus, seizure, low muscle tone/hypotonia and osteoporosis. Progress towards understanding and treating SRS requires a model that recapitulates human gene variants and disease presentations. Here, we evaluated molecular and neurological presentations in the G56S mouse model, which carries a missense mutation in the Sms gene. The lack of SMS protein in the G56S mice resulted in increased spermidine/spermine ratio, failure to thrive, short stature and reduced bone density. They showed impaired learning capacity, increased anxiety, reduced mobility and heightened fear responses, accompanied by reduced total and regional brain volumes. Furthermore, impaired mitochondrial oxidative phosphorylation was evident in G56S cerebral cortex, G56S fibroblasts and Sms-null hippocampal cells, indicating that SMS may serve as a future therapeutic target. Collectively, our study establishes the suitability of the G56S mice as a preclinical model for SRS and provides a set of molecular and functional outcome measures that can be used to evaluate therapeutic interventions for SRS.

Comprehensive review on lipid metabolism and RNA methylation: Biological mechanisms, perspectives and challenges

Adipose tissue plays a crucial role in maintaining energy balance, regulating hormones, and promoting metabolic health. To address disorders related to obesity and develop effective therapies, it is essential to have a deep understanding of adipose tissue biology. In recent years, RNA methylation has emerged as a significant epigenetic modification involved in various cellular functions and metabolic pathways. Particularly in the realm of adipogenesis and lipid metabolism, extensive research is ongoing to uncover the mechanisms and functional importance of RNA methylation. Increasing evidence suggests that RNA methylation plays a regulatory role in adipocyte development, metabolism, and lipid utilization across different organs. This comprehensive review aims to provide an overview of common RNA methylation modifications, their occurrences, and regulatory mechanisms, focusing specifically on their intricate connections to fat metabolism. Additionally, we discuss the research methodologies used in studying RNA methylation and highlight relevant databases that can aid researchers in this rapidly advancing field.

Hepatic nutrient and hormone signaling to mTORC1 instructs the postnatal metabolic zonation of the liver

The metabolic functions of the liver are spatially organized in a phenomenon called zonation, linked to the differential exposure of portal and central hepatocytes to nutrient-rich blood. The mTORC1 signaling pathway controls cellular metabolism in response to nutrients and insulin fluctuations. Here we show that simultaneous genetic activation of nutrient and hormone signaling to mTORC1 in hepatocytes results in impaired establishment of postnatal metabolic and zonal identity of hepatocytes. Mutant hepatocytes fail to upregulate postnatally the expression of Frizzled receptors 1 and 8, and show reduced Wnt/β-catenin activation. This defect, alongside diminished paracrine Wnt2 ligand expression by endothelial cells, underlies impaired postnatal maturation. Impaired zonation is recapitulated in a model of constant supply of nutrients by parenteral nutrition to piglets. Our work shows the role of hepatocyte sensing of fluctuations in nutrients and hormones for triggering a latent metabolic zonation program.

Endothelial TET2 regulates the white adipose browning and metabolism via fatty acid oxidation in obesity

Obesity is a complex metabolic disorder, manifesting as excessive accumulation of body fat. Ten-Eleven Translocation-2 (TET2) has garnered significant attention in the context of obesity due to its crucial role in epigenetic regulation and metabolic homeostasis. In this study, we aimed to investigate the effect of endothelial TET2 on obesity and explore the potential mechanism. We generated endothelial cell-specific TET2 deficiency mice and investigated endothelial TET2 using transcriptomic and epigenomic analyses. We determined the downregulation of endothelial TET2 in white adipose tissues. Furthermore, we identified that endothelial TET2 loss aggravated high-fat diet-induced obesity by inhibiting vascularization and thus suppressing white adipose tissue browning. Mechanistically, endothelial TET2 modulates obesity by engaging in endothelial fatty acid oxidation and angiocrine-mediated secretion of bone morphogenetic protein 4 (BMP4), in which nuclear factor-erythroid 2-related factor 2 (NRF2) serves as a key mediator. Our study reveals that endothelial TET2 regulates white adipose tissue browning by interacting with NRF2 to facilitate fatty acid oxidation and lipolysis in adipocytes.

Obesogenic diet disrupts tissue-specific mitochondrial gene signatures in the artery and capillary endothelium

Endothelial cells (ECs) adapt to the unique needs of their resident tissue and metabolic perturbations, such as obesity. We sought to understand how obesity affects EC metabolic phenotypes, specifically mitochondrial gene expression. We investigated the mesenteric and adipose endothelium because these vascular beds have distinct roles in lipid homeostasis. Initially, we performed bulk RNA sequencing on ECs from mouse adipose and mesenteric vasculatures after a normal chow (NC) diet or high-fat diet (HFD) and found higher mitochondrial gene expression in adipose ECs compared with mesenteric ECs in both NC and HFD mice. Next, we performed single-cell RNA sequencing and categorized ECs as arterial, capillary, venous, or lymphatic. We found mitochondrial genes to be enriched in adipose compared with mesentery under NC conditions in artery and capillary ECs. After HFD, these genes were decreased in adipose ECs, becoming like mesenteric ECs. Transcription factor analysis revealed that peroxisome proliferator-activated receptor-γ (PPAR-γ) had high specificity in NC adipose artery and capillary ECs. These findings were recapitulated in single-nuclei RNA-sequencing data from human visceral adipose. The sum of these findings suggests that mesenteric and adipose arterial ECs metabolize lipids differently, and the transcriptional phenotype of the vascular beds converges in obesity due to downregulation of PPAR-γ in adipose artery and capillary ECs.NEW & NOTEWORTHY Using bulk and single-cell RNA sequencing on endothelial cells from adipose and mesentery, we found that an obesogenic diet induces a reduction in adipose endothelial oxidative phosphorylation gene expression, resulting in a phenotypic convergence of mesenteric and adipose endothelial cells. Furthermore, we found evidence that PPAR-γ drives this phenotypic shift. Mining of human data sets segregated based on body mass index supported these findings. These data point to novel mechanisms by which obesity induces endothelial dysfunction.

Metabolic flux analysis in adipose tissue reprogramming

Obesity is a growing epidemic in the United States and worldwide and is associated with insulin resistance and cardiovascular disease, among other comorbidities. Understanding of the pathology that links overnutrition to these disease processes is ongoing. Adipose tissue is a heterogeneous organ comprised of multiple different cell types and it is likely that dysregulated metabolism within these cell populations disrupts both inter- and intracellular interactions and is a key driver of human disease. In recent years, metabolic flux analysis, which offers a precise quantification of metabolic pathway fluxes in biological systems, has emerged as a candidate strategy for uncovering the metabolic changes that stoke these disease processes. In this mini review, we discuss metabolic flux analysis as an experimental tool, with a specific emphasis on mass spectrometry with isotope tracing as this is the technique most frequently used for metabolic flux analysis in adipocytes. Furthermore, we examine existing literature that uses metabolic flux analysis to further our understanding of adipose tissue biology. Our group has a specific interest in understanding the role of white adipose tissue inflammation in the progression of cardiometabolic disease, as we know that in obesity the accumulation of pro-inflammatory adipose tissue macrophages is associated with significant morbidity, so we use this as a paradigm throughout our review for framing the application of these experimental techniques. However, there are many other biological applications to which they can be applied to further understanding of not only adipose tissue biology but also systemic homeostasis.

The evolving functions of the vasculature in regulating adipose tissue biology in health and obesity

Adipose tissue is an endocrine organ and a crucial regulator of energy storage and systemic metabolic homeostasis. Additionally, adipose tissue is a pivotal regulator of cardiovascular health and disease, mediated in part by the endocrine and paracrine secretion of several bioactive products, such as adipokines. Adipose vasculature has an instrumental role in the modulation of adipose tissue expansion, homeostasis and metabolism. The role of the adipose vasculature has been extensively explored in the context of obesity, which is recognized as a global health problem. Obesity-induced accumulation of fat, in combination with vascular rarefaction, promotes adipocyte dysfunction and induces oxidative stress, hypoxia and inflammation. It is now recognized that obesity-associated endothelial dysfunction often precedes the development of cardiovascular diseases. Investigations have revealed heterogeneity within the vascular niche and dynamic reciprocity between vascular and adipose cells, which can become dysregulated in obesity. Here we provide a comprehensive overview of the evolving functions of the vasculature in regulating adipose tissue biology in health and obesity.

Adipose tissue lipid metabolism: lipolysis

White adipose tissue stores fatty acid (FA) as triglyceride in the lipid droplet organelle of highly specialized cells known as fat cells or adipocytes. Depending on the nutritional state and energy demand, hormonal and biochemical signals converge on activating an elegant and fundamental process known as lipolysis, which involves triglyceride hydrolysis to FAs. Almost six decades of work have vastly expanded our knowledge of lipolysis from enzymatic processes to complex protein assembly, disassembly, and post-translational modification. Research in recent decades ushered in the discovery of new lipolytic enzymes and coregulators and the characterization of numerous factors and signaling pathways that regulate lipid hydrolysis on transcriptional and post-transcriptional levels. This review will discuss recent developments with particular emphasis on the past two years in enzymatic lipolytic pathways and transcriptional regulation of lipolysis. We will summarize the positive and negative regulators of lipolysis, the adipose tissue microenvironment in lipolysis, and the systemic effects of lipolysis. The dynamic nature of adipocyte lipolysis is emerging as an essential regulator of metabolism and energy balance, and we will discuss recent developments in this area.

Type 2 Immunity Regulates Dermal White Adipose Tissue Function

Type 2 immune responses have been increasingly linked with tissue maintenance, regeneration, and metabolic homeostasis. The molecular basis of regulator and effector mechanisms of type 2 immunity in skin regeneration and homeostasis is still lacking. In this study, we analyzed the role of IL-4Rα signaling in the regeneration of diverse cellular compartments in the skin. Mutants with global IL-4Rα deficiency showed two major phenotypes: first, a pronounced atrophy of the interfollicular epidermis, and second, a significant increase in dermal white adipose tissue thickness in mice aged 3 weeks (postnatal day 21) compared with littermate controls. Notably, IL-4Rα deficiency decreased the activation of hormone-sensitive lipase, a rate-limiting step in lipolysis. Immunohistochemical and FACS analysis in IL-4/enhanced GFP reporter mice showed that IL-4 expression peaked on postnatal day 21 and that eosinophils are the predominant IL-4-expressing cells. Eosinophil-deficient mice recapitulated the lipolytic-defective dermal white adipose tissue phenotype of Il4ra-deficient mice, showing that eosinophils are necessary for dermal white adipose tissue lipolysis. Collectively, we provide mechanistic insights into the regulation of interfollicular epidermis and hormone-sensitive lipase-mediated lipolysis in dermal white adipose tissue in early life by IL-4Rα, and our findings show that eosinophils play a critical role in this process.

Adipose tissue endothelial cells: insights into their heterogeneity and functional diversity

Cardiovascular disease is the leading cause of death globally. Endothelial cells (ECs), the key units of all vascular segments, have a significant impact on the health and disease of organisms. Adipose tissue is vital to cardiovascular health, therefore, understanding adipose EC (AdEC) biology is important. Recent data have highlighted the presence of distinct AdEC subpopulations that govern adipose tissue homeostasis. In addition to their role in nutrient metabolism and transport, AdECs are involved in bidirectional cellular communication with adipocytes, among other cells. These interactions are mainly mediated by paracrine factors, including noncoding RNAs. In this review, we highlight recent results showcasing the functions of AdECs in adipose tissue biology, metabolic homeostasis, and changes occurring in obesity.

Deletion of endothelial leptin receptors in mice promotes diet-induced obesity

Obesity promotes endothelial dysfunction. Endothelial cells not only respond, but possibly actively promote the development of obesity and metabolic dysfunction. Our aim was to characterize the role of endothelial leptin receptors (LepR) for endothelial and whole body metabolism and diet-induced obesity. Mice with tamoxifen-inducible, Tie2.Cre-ER^T2-mediated deletion of LepR in endothelial cells (End.LepR knockout, KO) were fed high-fat diet (HFD) for 16 weeks. Body weight gain, serum leptin levels, visceral adiposity and adipose tissue inflammation were more pronounced in obese End.LepR-KO mice, whereas fasting serum glucose and insulin levels or the extent of hepatic steatosis did not differ. Reduced brain endothelial transcytosis of exogenous leptin, increased food intake and total energy balance were observed in End.LepR-KO mice and accompanied by brain perivascular macrophage accumulation, whereas physical activity, energy expenditure and respiratory exchange rates did not differ. Metabolic flux analysis revealed no changes in the bioenergetic profile of endothelial cells from brain or visceral adipose tissue, but higher glycolysis and mitochondrial respiration rates in those isolated from lungs. Our findings support a role for endothelial LepRs in the transport of leptin into the brain and neuronal control of food intake, and also suggest organ-specific changes in endothelial cell, but not whole-body metabolism.

Endothelial cell-derived stem cell factor promotes lipid accumulation through c-Kit-mediated increase of lipogenic enzymes in brown adipocytes

Active thermogenesis in the brown adipose tissue (BAT) facilitating the utilization of lipids and glucose is critical for maintaining body temperature and reducing metabolic diseases, whereas inactive BAT accumulates lipids in brown adipocytes (BAs), leading to BAT whitening. Although cellular crosstalk between endothelial cells (ECs) and adipocytes is essential for the transport and utilization of fatty acid in BAs, the angiocrine roles of ECs mediating this crosstalk remain poorly understood. Using single-nucleus RNA sequencing and knock-out male mice, we demonstrate that stem cell factor (SCF) derived from ECs upregulates gene expressions and protein levels of the enzymes for de novo lipogenesis, and promotes lipid accumulation by activating c-Kit in BAs. In the early phase of lipid accumulation induced by denervation or thermoneutrality, transiently expressed c-Kit on BAs increases the protein levels of the lipogenic enzymes via PI3K and AKT signaling. EC-specific SCF deletion and BA-specific c-Kit deletion attenuate the induction of the lipogenic enzymes and suppress the enlargement of lipid droplets in BAs after denervation or thermoneutrality in male mice. These data provide insight into SCF/c-Kit signaling as a regulator that promotes lipid accumulation through the increase of lipogenic enzymes in BAT when thermogenesis is inhibited.

Liraglutide promotes angiogenesis in adipose tissue via suppression of adipocyte-derived IL-6

Accumulating evidence suggests that Liraglutide is a favorable treatment for obese people. Obesity induces cellular senescence and accumulated senescent adipocytes in adipose tissue. However, the role of Liraglutide in adipose tissue (AT) senescence and the underlying mechanisms remain obscure. In this study, we found that HFD induces adipocyte senescence and impaired angiogenesis in AT. The deleterious effects provoked unhealthy adipose tissue remodeling and metabolic disturbance. In contrast, treatment of Liraglutide promoted weight reduction, alleviated adipose tissue senescence, and improved angiogenesis in AT. Notably, we demonstrated that Liraglutide promotes angiogenesis in AT dependent on adipocyte-derived IL-6. These findings revealed distinctive roles of Liraglutide in the regulation of adipocyte senescence and provide a therapeutic potential to obesity-associated metabolic disorders.

Endotheliopathy in the metabolic syndrome: Mechanisms and clinical implications

The increasing prevalence of the metabolic syndrome (MetS) is a threat to global public health due to its lethal complications. Nonalcoholic fatty liver disease (NAFLD) is the hepatic manifestation of the MetS characterized by hepatic steatosis, which is potentially progressive to the inflammatory and fibrotic nonalcoholic steatohepatitis (NASH). The adipose tissue (AT) is also a major metabolic organ responsible for the regulation of whole-body energy homeostasis, and thereby highly involved in the pathogenesis of the MetS. Recent studies suggest that endothelial cells (ECs) in the liver and AT are not just inert conduits but also crucial mediators in various biological processes via the interaction with other cell types in the microenvironment both under physiological and pathological conditions. Herein, we highlight the current knowledge of the role of the specialized liver sinusoidal endothelial cells (LSECs) in NAFLD pathophysiology. Next, we discuss the processes through which AT EC dysfunction leads to MetS progression, with a focus on inflammation and angiogenesis in the AT as well as on endothelial-to-mesenchymal transition of AT-ECs. In addition, we touch upon the function of ECs residing in other metabolic organs including the pancreatic islet and the gut, the dysregulation of which may also contribute to the MetS. Finally, we highlight potential EC-based therapeutic targets for human MetS, and NASH based on recent achievements in basic and clinical research and discuss how to approach unsolved problems in the field.

Impaired polyamine metabolism causes behavioral and neuroanatomical defects in a novel mouse model of Snyder-Robinson Syndrome

Polyamines (putrescine, spermidine, and spermine) are essential molecules for normal cellular functions and are subject to strict metabolic regulation. Mutations in the gene encoding spermine synthase (SMS) lead to accumulation of spermidine in an X-linked recessive disorder known as Snyder-Robinson syndrome (SRS). Presently, no treatments exist for this rare disease that manifests with a spectrum of symptoms including intellectual disability, developmental delay, thin habitus, and low muscle tone. The development of therapeutic interventions for SRS will require a suitable disease-specific animal model that recapitulates many of the abnormalities observed in patients. Here, we characterize the molecular, behavioral, and neuroanatomical features of a mouse model with a missense mutation in Sms gene that results in a glycine-to-serine substitution at position 56 (G56S) of the SMS protein. Mice harboring this mutation exhibit a complete loss of SMS protein and elevated spermidine/spermine ratio in skeletal muscles and the brain. In addition, the G56S mice demonstrate increased anxiety, impaired learning, and decreased explorative behavior in fear conditioning, Morris water maze, and open field tests, respectively. Furthermore, these mice failed to gain weight over time and exhibit abnormalities in brain structure and bone density. Transcriptomic analysis of the cerebral cortex revealed downregulation of genes associated with mitochondrial oxidative phosphorylation and ribosomal protein synthesis. Our findings also revealed impaired mitochondrial bioenergetics in fibroblasts isolated from the G56S mice, indicating a correlation between these processes in the affected mice. Collectively, our findings establish the first in-depth characterization of an SRS preclinical mouse model that identifies cellular processes that could be targeted for future therapeutic development.

Probiotic induced synthesis of microbiota polyamine as a nutraceutical for metabolic syndrome and obesity-related type 2 diabetes

The gut microbiota regulates multiple facets of host metabolism and immunity through the production of signaling metabolites, such as polyamines which are small organic compounds that are essential to host cell growth and lymphocyte activation. Polyamines are most abundant in the intestinal lumen, where their synthesis by the gut microbiota is influenced by microbiome composition and host diet. Disruption of the host gut microbiome in metabolic syndrome and obesity-related type 2 diabetes (obesity/T2D) results in potential dysregulation of polyamine synthesis. A growing body of evidence suggests that restoration of the dysbiotic gut microbiota and polyamine synthesis is effective in ameliorating metabolic syndrome and strengthening the impaired immune responses of obesity/T2D. In this review, we discuss existing studies on gut microbiome determinants of polyamine synthesis, polyamine production in obesity/T2D, and evidence that demonstrates the potential of polyamines as a nutraceutical in obesity/T2D hosts.

Genetically personalised organ-specific metabolic models in health and disease

Understanding how genetic variants influence disease risk and complex traits (variant-to-function) is one of the major challenges in human genetics. Here we present a model-driven framework to leverage human genome-scale metabolic networks to define how genetic variants affect biochemical reaction fluxes across major human tissues, including skeletal muscle, adipose, liver, brain and heart. As proof of concept, we build personalised organ-specific metabolic flux models for 524,615 individuals of the INTERVAL and UK Biobank cohorts and perform a fluxome-wide association study (FWAS) to identify 4312 associations between personalised flux values and the concentration of metabolites in blood. Furthermore, we apply FWAS to identify 92 metabolic fluxes associated with the risk of developing coronary artery disease, many of which are linked to processes previously described to play in role in the disease. Our work demonstrates that genetically personalised metabolic models can elucidate the downstream effects of genetic variants on biochemical reactions involved in common human diseases.

Cellular Senescence in Obesity and Associated Complications: a New Therapeutic Target

PURPOSE OF REVIEW

Obesity has increased worldwide recently and represents a major global health challenge. This review focuses on the obesity-associated cellular senescence in various organs and the role of these senescent cells (SnCs) in driving complications associated with obesity. Also, the ability to target SnCs pharmacologically with drugs termed senotherapeutics as a therapy for these complications is discussed.

RECENT FINDINGS

Several studies have shown a positive correlation between obesity and SnC burden in organs such as adipose tissue, liver, and pancreatic-β-cells. These SnCs produce several secretory factors which affect other cells and tissues in a paracrine manner resulting in organ dysfunction. The accumulation of SnCs in adipocytes affects their lipid storage and impairs adipogenesis. The inflammatory senescence-associated secretory phenotype (SASP) of SnCs downregulates the antioxidant capacity and mitochondrial function in tissues. Senescent hepatocytes cannot oxidize fatty acids, which leads to lipid deposition and senescence in β-cells decrease function. These and other adverse effects of SnCs contribute to insulin resistance and type-2 diabetes. The reduction in the SnC burden genetically or pharmacologically improves the complications associated with obesity. The accumulation of SnCs with age and disease accelerates aging. Obesity is a key driver of SnC accumulation, and the complications associated with obesity can be controlled by reducing the SnC burden. Thus, senotherapeutic drugs have the potential to be an effective therapeutic option.

Comprehensive Review of the Vascular Niche in Regulating Organ Regeneration and Fibrosis

The vasculature occupies a large area of the body, and none of the physiological activities can be carried out without blood vessels. Blood vessels are not just passive conduits and barriers for delivering blood and nutrients. Meanwhile, endothelial cells covering the vascular lumen establish vascular niches by deploying some growth factors, known as angiocrine factors, and actively participate in the regulation of a variety of physiological processes, such as organ regeneration and fibrosis and the occurrence and development of cancer. After organ injury, vascular endothelial cells regulate the repair process by secreting various angiocrine factors, triggering the proliferation and differentiation process of stem cells. Therefore, analyzing the vascular niche and exploring the factors that maintain vascular homeostasis can provide strong theoretical support for clinical treatment targeting blood vessels. Here we mainly discuss the regulatory mechanisms of the vascular niche in organ regeneration and fibrosis.

Using Untargeted LC-MS Metabolomics to Identify the Association of Biomarkers in Cattle Feces with Marbling Standard Longissimus Lumborum

Background: To improve the grade of beef marbling has great economic value in the cattle industry since marbling has the traits of high quality and comprehensive nutrition. And because of the marbling’s importance and complexity, it is indispensable to explore marbled beef at multiple levels. This experiment studied the relationship between fecal metabolites and marbling characters, and further screened biomarkers. Results: We performed fecal metabolomics analysis on 30 individuals selected from 100 crossbreed cattle (Luxi Yellow cattle ♀ × Japanese Wagyu cattle ♂), 15 with an extremely high-grade marbling beef and 15 with an extremely low-grade marbling beef. A total of 9959 and 8389 m/z features were detected in positive ionization and negative ionization mode by liquid chromatography-mass spectrometry (LC-MS). Unfortunately, the sample separation in the PCA is not obvious, and the predictive ability of the orthogonal partial least squares discrimination analysis (OPLS-DA) model is not good. However, we got six differential metabolites filtered by VIP > 1 and p < 0.05. After that, we used weighted correlation network analysis (WGCNA) and found out a module in each positive and negative mode most related to the trait of marbling beef, and then identified three metabolites in positive mode. By further annotation of the Kyoto encyclopedia of genes and genomes (KEGG), it was found that these metabolites involved a variety of metabolic ways, including sphingomyelin metabolism, linoleic acid metabolism, glycerophospholipid metabolism, and so on. Finally, receiver operating characteristic (ROC) analysis was used to evaluate the predictability of metabolites, and the result showed that SM(d18:0/16:1(9Z)) (AUC = 0.72), PC(15:0/18:2(9Z,12Z)) (AUC = 0.72), ADP (AUC = 0.71), PC(16:0/16:0) (AUC = 0.73), and 3-O-Sulfogalactosylceramide (d18:1/18:0) (AUC = 0.69) have an accuracy diagnosis. Conclusions: In conclusion, this study supports new opinions for the successive evaluation of marbling beef through metabolites. Furthermore, six non-invasive fecal metabolites that can evaluate beef marbling grade were found, including SM(d18:0/16:1(9Z)), PC(15:0/18:2(9Z,12Z)), ADP, PC(16:0/16:0), and 3-O-Sulfogalactosylceramide.

When, where and which PIK3CA mutations are pathogenic in congenital disorders

PIK3CA encodes the class I PI3Kα isoform and is frequently mutated in cancer. Activating mutations in PIK3CA also cause a range of congenital disorders featuring asymmetric tissue overgrowth, known as the PIK3CA-related overgrowth spectrum (PROS), with frequent vascular involvement. In PROS, PIK3CA mutations arise postzygotically, during embryonic development, leading to a mosaic body pattern distribution resulting in a variety of phenotypic features. A clear skewed pattern of overgrowth favoring some mesoderm-derived and ectoderm-derived tissues is observed but not understood. Here, we summarize our current knowledge of the determinants of PIK3CA-related pathogenesis in PROS, including intrinsic factors such as cell lineage susceptibility and PIK3CA variant bias, and extrinsic factors, which refers to environmental modifiers. We also include a section on PIK3CA-related vascular malformations given that the vasculature is frequently affected in PROS. Increasing our biological understanding of PIK3CA mutations in PROS will contribute toward unraveling the onset and progression of these conditions and ultimately impact on their treatment. Given that PIK3CA mutations are similar in PROS and cancer, deeper insights into one will also inform about the other.

Angiogenesis in adipose tissue and obesity

While most tissues exhibit their greatest growth during development, adipose tissue is capable of additional massive expansion in adults. Adipose tissue expandability is advantageous when temporarily storing fuel for use during fasting, but becomes pathological upon continuous food intake, leading to obesity and its many comorbidities. The dense vasculature of adipose tissue provides necessary oxygen and nutrients, and supports delivery of fuel to and from adipocytes under fed or fasting conditions. Moreover, the vasculature of adipose tissue comprises a major niche for multipotent progenitor cells, which give rise to new adipocytes and are necessary for tissue repair. Given the multiple, pivotal roles of the adipose tissue vasculature, impairments in angiogenic capacity may underlie obesity-associated diseases such as diabetes and cardiometabolic disease. Exciting new studies on the single-cell and single-nuclei composition of adipose tissues in mouse and humans are providing new insights into mechanisms of adipose tissue angiogenesis. Moreover, new modes of intercellular communication involving micro vesicle and exosome transfer of proteins, nucleic acids and organelles are also being recognized to play key roles. This review focuses on new insights on the cellular and signaling mechanisms underlying adipose tissue angiogenesis, and on their impact on obesity and its pathophysiological consequences.

A new signal that shrinks fat

Healthy white adipose tissue is dependent on proliferation of endothelial cells to maintain homeostasis or undergo expansion. A new study shows that endothelial cells communicate with adipocytes via polyamines to promote vascularization of adipose tissue, thereby reversing the metabolic effects of obesity.