Enlarged adipocytes from subcutaneous vs. visceral adipose tissue differentially contribute to metabolic dysfunction and atherogenic risk of patients with obesity

Exposure to gestational diabetes mellitus increases subclinical inflammation mediated in part by obesity

Gestational diabetes mellitus (GDM) is a frequent and serious complication of pregnancy, often associated with obesity. Metabolic dysfunction and metainflammation are evident in both obesity and GDM. In this cross-sectional study, we aimed at defining the direct contribution of the immune system in GDM, across the main metabolic tissues, specifically focussing on elucidating the roles of obesity and GDM to the clinical outcome. Using immunoassays and multicolour flow cytometry, cytokine profiles and immune cell frequencies were measured in maternal circulation and central metabolic tissues [placenta and visceral adipose tissue (VAT)] in GDM-diagnosed (n = 28) and normal glucose tolerant (n = 32) women undergoing caesarean section. Participants were sub-grouped as non-obese [body mass index (BMI) < 30 kg/m2] or obese (BMI ≥ 30 kg/m2). Unsupervised data analysis was performed on the flow cytometry data set to identify functional alterations. GDM obese participants had significantly elevated circulating IL-6 and IL-17A levels. GDM non-obese participants had elevated circulating IL-12p70, elevated placental IL-17A, and VAT IFN-γ production. Unsupervised clustering of immune populations across the three biological sites simultaneously, identified different NK- and T-cell phenotypes that were altered in NGT obese and GDM non-obese participants, while a classical tissue monocyte cluster was increased in GDM obese participants. In this study, there was significant evidence of subclinical inflammation, and significant alterations in clusters of NK cells, T cells, and tissue monocyte populations in GDM. While increased adiposity assimilates with increased inflammation in the non-pregnant state, this overt relationship may not be as evident during pregnancy and warrants further examination in future longitudinal studies.

Defective Visceral Adipose Tissue Adaptation in Gestational Diabetes Mellitus

CONTEXT

Gestational diabetes mellitus (GDM) is a complex obstetric condition affecting localized glucose metabolism, resulting in systemic metabolic dysfunction.

OBJECTIVE

This cross-sectional study aimed to explore visceral adipose tissue (VAT) as an integral contributor to GDM, focusing on elucidating the specific contribution of obesity and GDM pathology to maternal outcomes.

METHODS

Fifty-six nulliparous pregnant women were recruited, including normal glucose tolerant (NGT) (n = 30) and GDM (n = 26) participants. Participants were subgrouped as nonobese (BMI <30 kg/m2) or obese (BMI ≥30 kg/m2). Metabolic markers in circulation, VAT, and placenta were determined. Morphological analysis of VAT and immunoblotting of the insulin signaling cascade were performed.

RESULTS

GDM participants demonstrated hyperinsulinemia and elevated homeostatic model assessment for insulin resistance (HOMA-IR) scores relative to NGT participants. The GDM-obese subgroup had significant VAT adipocyte hypoplasia relative to NGT-nonobese tissue. GDM-obese VAT had significantly lower insulin receptor substrate (IRS)-2 expression, with elevated ser312 phosphorylation of IRS-1, relative to NGT-nonobese. GDM-obese participants had significantly elevated circulating leptin levels and placental adipsin secretion, while GDM-nonobese participants had elevated circulating adipsin levels with reduced placental adiponectin secretion.

CONCLUSION

These findings suggest that GDM-obese pregnancy is specifically characterized by inadequate VAT remodeling and dysfunctional molecular signaling, which contribute to insulin resistance and hinder metabolic health.

The Role of Cdc42 in the Insulin and Leptin Pathways Contributing to the Development of Age-Related Obesity

Age-related obesity significantly increases the risk of chronic diseases such as type 2 diabetes, cardiovascular diseases, hypertension, and certain cancers. The insulin-leptin axis is crucial in understanding metabolic disturbances associated with age-related obesity. Rho GTPase Cdc42 is a member of the Rho family of GTPases that participates in many cellular processes including, but not limited to, regulation of actin cytoskeleton, vesicle trafficking, cell polarity, morphology, proliferation, motility, and migration. Cdc42 functions as an integral part of regulating insulin secretion and aging. Some novel roles for Cdc42 have also been recently identified in maintaining glucose metabolism, where Cdc42 is involved in controlling blood glucose levels in metabolically active tissues, including skeletal muscle, adipose tissue, pancreas, etc., which puts this protein in line with other critical regulators of glucose metabolism. Importantly, Cdc42 plays a vital role in cellular processes associated with the insulin and leptin signaling pathways, which are integral elements involved in obesity development if misregulated. Additionally, a change in Cdc42 activity may affect senescence, thus contributing to disorders associated with aging. This review explores the complex relationships among age-associated obesity, the insulin-leptin axis, and the Cdc42 signaling pathway. This article sheds light on the vast molecular web that supports metabolic dysregulation in aging people. In addition, it also discusses the potential therapeutic implications of the Cdc42 pathway to mitigate obesity since some new data suggest that inhibition of Cdc42 using antidiabetic drugs or antioxidants may promote weight loss in overweight or obese patients.

Gene coexpression network analysis reveals perirenal adipose tissue as an important target of prenatal malnutrition in sheep

We have previously demonstrated that pre- and early postnatal malnutrition in sheep induced depot- and sex-specific changes in adipose morphological features, metabolic outcomes, and transcriptome in adulthood, with perirenal (PER) as the major target followed by subcutaneous (SUB) adipose tissue. We aimed to identify coexpressed and hub genes in SUB and PER to identify the underlying molecular mechanisms contributing to the early nutritional programming of adipose-related phenotypic outcomes. Transcriptomes of SUB and PER of male and female adult sheep with different pre- and early postnatal nutrition histories were used to construct networks of coexpressed genes likely to be functionally associated with pre- and early postnatal nutrition histories and phenotypic traits using weighted gene coexpression network analysis. The modules from PER showed enrichment of cell cycle regulation, gene expression, transmembrane transport, and metabolic processes associated with both sexes' prenatal nutrition. In SUB (only males), a module of enriched adenosine diphosphate metabolism and development correlated with prenatal nutrition. Sex-specific module enrichments were found in PER, such as chromatin modification in the male network but histone modification and mitochondria- and oxidative phosphorylation-related functions in the female network. These sex-specific modules correlated with prenatal nutrition and adipocyte size distribution patterns. Our results point to PER as a primary target of prenatal malnutrition compared to SUB, which played only a minor role. The prenatal programming of gene expression and cell cycle, potentially through epigenetic modifications, might be underlying mechanisms responsible for observed changes in PER expandability and adipocyte-size distribution patterns in adulthood in both sexes.

Lupenone-Rich Fraction Derived from Cissus quadrangularis L. Suppresses Lipid Accumulation in 3T3-L1 Adipocytes

Cissus quadrangularis L. (CQ) has potential as a therapeutic for managing obesity and balancing metabolic activity, but the main bioactive compound and regulatory mechanism remain unknown. Herein, the CQ hexane extract was fractionated into 30 fractions (CQ-H) using flash column chromatography and analyzed using thin-layer chromatography. The direct antiadipogenesis effect of CQ-H fractions was tested on 3T3-L1 preadipocytes. Lupenone-rich fractions 2H and 3H were identified as containing potent antiadipogenesis agents that reduced differentiated cell numbers and intracellular lipid droplet size. Although the overall mitochondrial density remained unchanged, differentiated cells exhibited a higher mitochondrial density than that in non-differentiated cells. Additionally, 2H increased mitochondrial activity in both cell types as shown by their differentiation and lipid formation stages. Lupenone was isolated from 2H (Lu-CQ) and shown to dose-dependently inhibit adipogenesis, with 2H being more potent than Lu-CQ. Lu-CQ and 2H downregulated the expression of Pparg2 mRNA and upregulated that of glucose transporter genes, Slc2a1 and Slc2a4. Lu-CQ and 2H induced increased glucose uptake by 3T3-L1 cells. These findings suggest that lupenone-rich fractions in CQ contribute to balancing metabolic activity and reducing adipose tissue formation. Further exploration of CQ and its components may prompt innovative strategies for managing obesity and metabolic disorders.

GDF10 is related to obesity as an adipokine derived from subcutaneous adipose tissue

Introduction

Adipokines are proteins that are secreted by the adipose tissue. Although they are associated with obesity-related metabolic disorders, most studies have focused on adipokines expressed by visceral adipose tissue (VAT). This study aimed to identify the adipokine potentially derived from subcutaneous adipose tissue (SAT) and its clinical significance.

Methods

Samples of SAT and VAT were obtained from six adult male patients who underwent laparoscopic surgery for benign gall bladder disease. Differentially expressed genes were analyzed by subjecting the samples to RNA sequencing. The serum concentration of selected proteins according to body mass index (BMI) was analyzed in 58 individuals.

Results

GDF10 showed significantly higher expression in the SAT, as per RNA sequencing (fold change = 5.8, adjusted P value = 0.009). Genes related to insulin response, glucose homeostasis, lipid homeostasis, and fatty acid metabolism were suppressed when GDF10 expression was high in SAT, as per genotype-tissue expression data. The serum GDF10 concentration was higher in participants with BMI ≥ 25 kg/m² (n = 35, 2674 ± 441 pg/mL) than in those with BMI < 25 kg/m² (n = 23, 2339 ± 639 pg/mL; P = 0.022). There was a positive correlation between BMI and serum GDF10 concentration (r = 0.308, P = 0.019).

Conclusions

GDF10 expression was higher in SAT than in VAT. Serum GDF10 concentration was high in patients with obesity. Therefore, GDF10 could be a SAT-derived protein related to obesity.

Obesity and the risk of cardiometabolic diseases

The prevalence of obesity has reached pandemic proportions, and now approximately 25% of adults in Westernized countries have obesity. Recognized as a major health concern, obesity is associated with multiple comorbidities, particularly cardiometabolic disorders. In this Review, we present obesity as an evolutionarily novel condition, summarize the epidemiological evidence on its detrimental cardiometabolic consequences and discuss the major mechanisms involved in the association between obesity and the risk of cardiometabolic diseases. We also examine the role of potential moderators of this association, with evidence for and against the so-called 'metabolically healthy obesity phenotype', the 'fatness but fitness' paradox or the 'obesity paradox'. Although maintenance of optimal cardiometabolic status should be a primary goal in individuals with obesity, losing body weight and, particularly, excess visceral adiposity seems to be necessary to minimize the risk of cardiometabolic diseases.

Adipogenic and SWAT cells separate from a common progenitor in human brown and white adipose depots

Adipocyte function is a major determinant of metabolic disease, warranting investigations of regulating mechanisms. We show at single-cell resolution that progenitor cells from four human brown and white adipose depots separate into two main cell fates, an adipogenic and a structural branch, developing from a common progenitor. The adipogenic gene signature contains mitochondrial activity genes, and associates with genome-wide association study traits for fat distribution. Based on an extracellular matrix and developmental gene signature, we name the structural branch of cells structural Wnt-regulated adipose tissue-resident (SWAT) cells. When stripped from adipogenic cells, SWAT cells display a multipotent phenotype by reverting towards progenitor state or differentiating into new adipogenic cells, dependent on media. Label transfer algorithms recapitulate the cell types in human adipose tissue datasets. In conclusion, we provide a differentiation map of human adipocytes and define the multipotent SWAT cell, providing a new perspective on adipose tissue regulation.

Study on fatty acid binding protein in lipid metabolism of livestock and poultry

Fatty acid binding proteins (FABPs) are key proteins in lipid transport, and 12 family members have been documented in the literature. In recent years, new insights have been gained into the structure and function of FABPs, which are important regulators of lipid metabolic processes in the body and play a central role in coordinating lipid transport and metabolism in various tissues and organs across species. This paper provides a brief overview of the structure and biological functions of FABPs and reviews related studies on lipid metabolism in livestock and poultry to lay the foundation for research on the mechanism underlying the regulatory effect of FABPs on lipid metabolism in livestock and poultry and for the genetic improvement of livestock and poultry.

Estrogens in Adipose Tissue Physiology and Obesity-Related Dysfunction

Menopause-related decline in estrogen levels is accompanied by a change in adipose tissue distribution from a gynoid to an android and an increased prevalence of obesity in women. These unfavorable phenomena can be partially restored by hormone replacement therapy, suggesting a significant role for estrogen in the regulation of adipocytes' function. Indeed, preclinical studies proved the involvement of these hormones in adipose tissue development, metabolism, and inflammatory activity. However, the relationship between estrogen and obesity is bidirectional. On the one hand-their deficiency leads to excessive fat accumulation and impairs adipocyte function, on the other-adipose tissue of obese individuals is characterized by altered expression of estrogen receptors and key enzymes involved in their synthesis. This narrative review aims to summarize the role of estrogen in adipose tissue development, physiology, and in obesity-related dysfunction. Firstly, the estrogen classification, synthesis, and modes of action are presented. Next, their role in regulating adipogenesis and adipose tissue activity in health and the course of obesity is described. Finally, the potential therapeutic applications of estrogen and its derivates in obesity treatment are discussed.

Impact of White Adipose Tissue on Brain Structure, Perfusion, and Cognitive Function in Patients With Severe Obesity: The BARICO Study

BACKGROUND AND OBJECTIVE

While underlying pathophysiology linking obesity to brain health is not completely understood, white adipose tissue (WAT) is considered a key player. In obesity, WAT becomes dysregulated, showing hyperplasia, hypertrophy, and eventually inflammation. This disbalance leads to dysregulated secretion of adipokines influencing both (cardio)vascular and brain health. Within this study, we investigated the association between omental WAT (oWAT) and subcutaneous WAT (scWAT) with brain structure and perfusion and cognition in adults with severe obesity.

METHODS

Within the cross-sectional BARICO study, brain structure and perfusion and cognitive function were measured before bariatric surgery (BS) using MRI and cognitive assessments. During BS, oWAT and scWAT depots were collected and analyzed by histopathology. The number and diameter of adipocytes were quantified together with the amount of crown-like structures (CLS) as an indication of inflammation. Blood samples were collected to analyze adipokines and inflammatory markers. Neuroimaging outcomes included brain volumes, cortical thickness, white matter (WM) integrity, WM hyperintensities, cerebral blood flow using arterial spin labeling (ASL), and the ASL spatial coefficient of variation (sCoV), reflecting cerebrovascular health.

RESULTS

Seventy-one patients were included (mean age 45.1 ± 5.8 years; 83.1% women; mean body mass index 40.8 ± 3.8 kg/m²). scWAT showed more CLS (z = -2.72, p < 0.01, r = -0.24) and hypertrophy compared with oWAT (F(1,64) = 3.99, p < 0.05, η² = 0.06). Adiponectin levels were inversely associated with the average diameter of scWAT (β = -0.31, 95% CI -0.54 to -0.08) and oWAT (β = -0.33, 95% CI -0.55 to -0.09). Furthermore, the adipocyte diameter in oWAT was positively associated with the sCoV in the parietal cortex (β = 0.33, 95% CI 0.10-0.60), and the number of adipocytes (per mm²) was positively associated with sCoV in the nucleus accumbens (NAcc) (β = 0.34, 95% CI 0.09-0.61). Cognitive function did not correlate with any WAT parameter or plasma marker. These associations were highly influenced by age and sex. sCoV in the NAcc was positively associated with fasting plasma glucose (β = 0.35, 95% CI 0.10-0.56).

DISCUSSION

scWAT and oWAT are different in morphology and in their relationship with plasma markers and cerebrovascular health. Although scWAT showed more CLS and hypertrophy, scWAT was not associated with brain readouts. This study showed, however, important relationships between oWAT morphology and cerebrovascular health in obesity.

TRIAL REGISTRATION INFORMATION

Trial Registration Number NTR7288 (trialregister.nl/trial/7090).

Nonalcoholic Fatty Liver Disease and Adverse Pregnancy Outcomes in Women With Normal Prepregnant Weight

CONTEXT

Existing studies focusing on the effects of nonalcoholic fatty liver disease (NAFLD) combined with normal prepregnant weight on pregnancy outcomes are limited.

OBJECTIVE

This study aimed to explore the relationship between maternal NAFLD and adverse pregnancy outcomes in different body mass index (BMI) groups.

METHODS

Using an antenatal care and delivery database, we retrospectively analyzed women who delivered in Minhang Hospital affiliated to Fudan University, Shanghai, China from January 1, 2013, to June 30, 2020. NAFLD was confirmed by ultrasound in early pregnancy. A logistic regression model with adjustment for confounders was used to examine potential associations between NAFLD and pregnancy outcomes.

RESULTS

A total of 14 708 pregnant women (mean prepregnant BMI 21.0 [SD, 2.8] kg/m2) were included in our final study, of whom 554 (3.8%) had NAFLD. After fully adjusting for potential confounders, NAFLD significantly increased the risk of gestational diabetes mellitus (adjusted odds ratio 2.477; 95% CI, 1.885-3.254), gestational hypertension (3.054; 2.191-4.257), preeclampsia/eclampsia (3.994; 2.591-6.005), cesarean section (1.569; 1.315-1.872), preterm births (1.831; 1.229-2.727), and macrosomia (1.691; 1.300-2.198). It is notable that 83.9% (12 338) of women were of normal weight at the start of pregnancy (prepregnant 18.5 ≤ BMI < 24 kg/m2), and they still had higher odds of adverse pregnancy outcomes.

CONCLUSION

Women with NAFLD and a normal weight have a higher risk for adverse pregnancy outcomes. Pregnant women with NAFLD, regardless of obesity status, should be offered a more qualified surveillance to optimize pregnancy outcomes.

The Effect of Microbiome Therapies on Waist Circumference, a Measure of Central Obesity, in Patients with Type 2 Diabetes: A Systematic Review and Meta-analysis of Randomized Controlled Trials

BACKGROUND

Microbiome therapies (probiotic, prebiotic, and synbiotics) have been proposed as adjuvants in the control of central obesity; however, their results for patients with type 2 diabetes (T2D) remain inconclusive.

OBJECTIVE

The aim of this systematic review and meta-analysis was to evaluate the effect of microbiome therapies on central obesity as measured by waist circumference (WC), and to evaluate the effect of microbiome therapies for glycemic parameters (fasting glucose [FPG], fasting insulin [FPI], hemoglobin A1c [HbA1c], and insulin resistance [HOMA1-IR]) in patients with T2D.

METHODS

SCOPUS, Pubmed, EBSCO, and LILACS databases were searched for studies that investigated the effect of microbiome therapies on WC up to June 1, 2022. Heterogeneity was determined using Cochran's Q test and quantified using the inconsistency index. The random effects model was used to calculate the pooled difference in means (DM) and 95% confidence intervals (95%CI). Egger's test and Beggs-Muzamar's test were used to assess publication bias.

RESULTS

Fifteen reports were included (443 treated and 387 controls). Overall, a significant decrease in WC was found (DM = -0.97 cm; 95% confidence interval [95%CI] = -1.74 to -0.20; P = 0.014); however, when stratified by type of microbiome therapy, only probiotics significantly decreased WC (DM = -0.62 cm; 95%CI = -1.00 to -0.24; P = 0.002). No effect was observed for prebiotics and synbiotics. With respect to glycemic parameters, HbA1c, FPG, and HOMA1-IR significantly decrease with microbiome therapies (P ≤ 0.001). When stratified by the type of therapy, for probiotic treatments, HbA1c, FPG, and HOMA1-IR scores decrease (P < 0.001). For prebiotic treatments, HbA1c and FPG (P ≤ 0.001) levels decrease, whereas FPI increased (P = 0.012). Synbiotic treatments were only associated with an increase in FPI (P = 0.031).

CONCLUSION

Findings indicate that using probiotics alone improved WC in patients with T2D. Both probiotics and prebiotics decreased HbA1c and FPG; however, prebiotics and synbiotics resulted in an increase in FPI. The formulation of the therapy (single vs multi) had no difference on the effect.

Adipokines: Deciphering the cardiovascular signature of adipose tissue

Obesity and hypertension are intimately linked due to the various ways that the important cell types such as vascular smooth muscle cells (VSMC), endothelial cells (EC), immune cells, and adipocytes, communicate with one another to contribute to these two pathologies. Adipose tissue is a very dynamic organ comprised primarily of adipocytes, which are well known for their role in energy storage. More recently adipose tissue has been recognized as the largest endocrine organ because of its ability to produce a vast number of signaling molecules called adipokines. These signaling molecules stimulate specific types of cells or tissues with many adipokines acting as indicators of adipocyte healthy function, such as adiponectin, omentin, and FGF21, which show anti-inflammatory or cardioprotective effects, acting as regulators of healthy physiological function. Others, like visfatin, chemerin, resistin, and leptin are often altered during pathophysiological circumstances like obesity and lipodystrophy, demonstrating negative cardiovascular outcomes when produced in excess. This review aims to explore the role of adipocytes and their derived products as well as the impacts of these adipokines on blood pressure regulation and cardiovascular homeostasis.

The regulation of adipocyte growth in white adipose tissue

Adipocytes can increase in volume up to a thousand-fold, storing excess calories as triacylglycerol in large lipid droplets. The dramatic morphological changes required of adipocytes demands extensive cytoskeletal remodeling, including lipid droplet and plasma membrane expansion. Cell growth-related signalling pathways are activated, stimulating the production of sufficient amino acids, functional lipids and nucleotides to meet the increasing cellular needs of lipid storage, metabolic activity and adipokine secretion. Continued expansion gives rise to enlarged (hypertrophic) adipocytes. This can result in a failure to maintain growth-related homeostasis and an inability to cope with excess nutrition or respond to stimuli efficiently, ultimately leading to metabolic dysfunction. We summarize recent studies which investigate the functional and cellular structure remodeling of hypertrophic adipocytes. How adipocytes adapt to an enlarged cell size and how this relates to cellular dysfunction are discussed. Understanding the healthy and pathological processes involved in adipocyte hypertrophy may shed light on new strategies for promoting healthy adipose tissue expansion.

Discovery of a novel anti-obesity meroterpenoid agent targeted subcutaneous adipose tissue

BACKGROUND

Meroterpenoid furanasperterpene A (T2-3) with a novel 6/6/6/6/5 pentacyclic skeleton was isolated from the Aspergillus terreus GZU-31-1. Previously, we showed that T2-3 possessed significant lipid-lowering effects in 3T3-L1 adipocytes at 5 μM concentration. However, its therapeutic effect in metabolic disease and the underlying mechanisms of action remain unclear.

METHODS

High fat diet-induced obesity (DIO) mouse model and 3T3-L1 cell model were used to assess the anti-obesity effects of T2-3. Lipids in the adipocytes were examined by Oil Red O staining. β-catenin expression was examined by immunofluorescence and Western blotting, its activity was assessed by TOPflash/FOPflash assay.

RESULTS

T2-3 possessed potent anti-obesity effects in DIO mice, it significantly reduced body weight and subcutaneous adipose tissue (SAT) mass. Mechanistic studies showed that T2-3 significantly inhibited 3T3-L1 preadipocyte differentiation as indicated by the reduced number of mature adipocytes. The treatments also reduced the expressions of critical adipogenic transcription factors CEBP-α and PPAR-γ in both 3T3-L1 adipocytes and SAT in DIO mice. Interestingly, T2-3 increased the cytoplasmic and nuclear expressions of β-catenin and the transcriptional activity of β-catenin in 3T3-L1 adipocytes; the elevated β-catenin expression was also observed in SAT of the T2-3-treated DIO mice. Indeed, upregulation of β-catenin activity suppressed adipogenesis, while β-catenin inhibitor JW67 reversed the anti-adipogenic effect of T2-3. Taken together, our data suggest that T2-3 inhibits adipogenesis by upregulating β-catenin activity.

CONCLUSIONS

Our study is the first report demonstrating meroterpenoid furanasperterpene A as a novel 6/6/6/6/5 pentacyclic skeleton (T2-3) that possesses potent anti-adipogenic effect by targeting β-catenin signaling pathway. Our findings drive new anti-obesity drug discovery and provide drug leads for chemists and pharmacologists.

Parental obesity-induced changes in developmental programming

Many studies support the link between parental obesity and the predisposition to develop adult-onset metabolic syndromes that include obesity, high blood pressure, dyslipidemia, insulin resistance, and diabetes in the offspring. As the prevalence of obesity increases in persons of childbearing age, so does metabolic syndrome in their descendants. Understanding how parental obesity alters metabolic programs in the progeny, predisposing them to adult-onset metabolic syndrome, is key to breaking this cycle. This review explores the basis for altered metabolism of offspring exposed to overnutrition by focusing on critical developmental processes influenced by parental obesity. We draw from human and animal model studies, highlighting the adaptations in metabolism that occur during normal pregnancy that become maladaptive with obesity. We describe essential phases of development impacted by parental obesity that contribute to long-term alterations in metabolism in the offspring. These encompass gamete formation, placentation, adipogenesis, pancreas development, and development of brain appetite control circuits. Parental obesity alters the developmental programming of these organs in part by inducing epigenetic changes with long-term consequences on metabolism. While exposure to parental obesity during any of these phases is sufficient to alter long-term metabolism, offspring often experience multiple exposures throughout their development. These insults accumulate to increase further the susceptibility of the offspring to the obesogenic environments of modern society.

Of mice and men: Pinpointing species differences in adipose tissue biology

The prevalence of obesity and metabolic diseases continues to rise, which has led to an increased interest in studying adipose tissue to elucidate underlying disease mechanisms. The use of genetic mouse models has been critical for understanding the role of specific genes for adipose tissue function and the tissue’s impact on other organs. However, mouse adipose tissue displays key differences to human fat, which has led, in some cases, to the emergence of some confounding concepts in the adipose field. Such differences include the depot-specific characteristics of visceral and subcutaneous fat, and divergences in thermogenic fat phenotype between the species. Adipose tissue characteristics may therefore not always be directly compared between species, which is important to consider when setting up new studies or interpreting results. This mini review outlines our current knowledge about the cell biological differences between human and mouse adipocytes and fat depots, highlighting some examples where inadequate knowledge of species-specific differences can lead to confounding results, and presenting plausible anatomic explanations that may underlie the differences. The article thus provides critical insights and guidance for researchers working primarily with only human or mouse fat tissue, and may contribute to new ideas or concepts in the important and evolving field of adipose biology.

Combined resistance and aerobic training improves lung function and mechanics and fibrotic biomarkers in overweight and obese women

Background: Obesity impairs lung function and mechanics and leads to low-grade inflammation, but the effects of combined physical exercise (CPE) on that are unknown.

Methods: We investigated the effects of 12 weeks of combined physical exercise (aerobic + resistance training), in non-obese (n = 12), overweight (n = 17), and obese grade I (n = 11) women. Lung function and lung mechanics were evaluated. The systemic immune response was evaluated by whole blood analysis and biomarker measurements, while pulmonary fibrotic biomarkers were evaluated in the breath condensate.

Result: CPE improved forced vital capacity (FVC) % (p < 0.001) and peak expiratory flow (PEF) % (p < 0.0003) in the obese group; resistance of the respiratory system (R5Hz) in non-obese (p < 0.0099), overweight (p < 0.0005), and obese (p < 0.0001) groups; resistance of proximal airways (R20Hz) in non-obese (p < 0.01), overweight (p < 0.0009), and obese (p < 0.0001) groups; resistance of distal airways (R5Hz–R20Hz) in non-obese (p < 0.01), overweight (p < 0.0012), and obese (p < 0.0001) groups; reactance of the respiratory system (X5Hz) in non-obese (p < 0.01), overweight (p < 0.0006), and obese (p < 0.0005) groups; impedance of the respiratory system (Z5Hz) in non-obese (p < 0.0099), overweight (p < 0.0005), and obese (p < 0.0001) groups; central resistance (RCentral) in non-obese (p < 0.01), overweight (p < 0.001), and obese (p < 0.0003) groups; and the peripheral resistance (RPeripheral) in non-obese (p < 0.03), overweight (p < 0.001), and obese (p < 0.0002) groups. CPE reduced the pro-fibrotic IGF-1 levels in BC in overweight (p < 0.0094) and obese groups (p < 0.0001) and increased anti-fibrotic Klotho levels in BC in obese (p < 0.0001) groups, and reduced levels of exhaled nitric oxide in overweight (p < 0.03) and obese (p < 0.0001) groups.

Conclusion: CPE improves lung function, mechanics, and pulmonary immune response in overweight and obese grade I women by increasing anti-fibrotic protein Klotho and reducing pro-fibrotic IGF-1.

Obesity-Associated Cancers: Evidence from Studies in Mouse Models

Obesity, one of the major problems in modern human society, is correlated with various diseases, including type 2 diabetes mellitus (T2DM). In particular, epidemiological and experimental evidence indicates that obesity is closely linked to at least 13 different types of cancer. The mechanisms that potentially explain the link between obesity and cancer include hyperactivation of the IGF pathway, metabolic dysregulation, dysfunctional angiogenesis, chronic inflammation, and interaction between pro-inflammatory cytokines, endocrine hormones, and adipokines. However, how the largely uniform morbidity of obesity leads to different types of cancer still needs to be investigated. To study the link between obesity and cancer, researchers have commonly used preclinical animal models, particularly mouse models. These models include monogenic models of obesity (e.g., ob/ob and db/db mice) and genetically modified mouse models of human cancers (e.g., Kras-driven pancreatic cancer, Apc-mutated colorectal cancer, and Her2/neu-overexpressing breast cancer). The experimental results obtained using these mouse models revealed strong evidence of a link between obesity and cancer and suggested their underlying mechanisms.

The Phenotype of the Adipocytes Derived from Subcutaneous and Visceral ADMSCs Is Altered When They Originate from Morbidly Obese Women: Is There a Memory Effect?

Adipose tissue is an abundant source of mesenchymal stem cells (ADMSCs). Evidence has suggested that depot-specific ADMSCs (obtained from subcutaneous or visceral adipose tissue-subADMSCs or visADMSCs, respectively) account for differential responses of each depot to metabolic challenges. However, little is known about the phenotype and changes in metabolism of the adipocytes derived from ADMSCs of obese individuals. Therefore, we investigated the phenotypic and metabolic characteristics, particularly the lipid profile, of fully differentiated adipocytes derived from ADMSCs of lean and obese (with/without metabolic syndrome) postmenopausal women. We observed a depot-specific pattern, with more pronounced changes present in the adipocytes obtained from subADMSCs. Namely, chronic oversupply of fatty acids (present in morbid obesity) triggered an increase in CD36/SR-B2 and FATP4 protein content (total and cell surface), which translated to an increased LCFA influx (3H-palmitate uptake). This was associated with the accumulation of TAG and DAG in these cells. Furthermore, we observed that the adipocytes of visADMSCs origin were larger and showed smaller granularity than their counterparts of subADMSCs descent. Although ADMSCs were cultured in vitro, in a fatty acids-deprived environment, obesity significantly influenced the functionality of the progenitor adipocytes, suggesting the existence of a memory effect.

The Molecular Brakes of Adipose Tissue Lipolysis

Adaptation to changes in energy availability is pivotal for the survival of animals. Adipose tissue, the body’s largest reservoir of energy and a major source of metabolic fuel, exerts a buffering function for fluctuations in nutrient availability. This functional plasticity ranges from energy storage in the form of triglycerides during periods of excess energy intake to energy mobilization via lipolysis in the form of free fatty acids for other organs during states of energy demands. The subtle balance between energy storage and mobilization is important for whole-body energy homeostasis; its disruption has been implicated as contributing to the development of insulin resistance, type 2 diabetes and cancer cachexia. As a result, adipocyte lipolysis is tightly regulated by complex regulatory mechanisms involving lipases and hormonal and biochemical signals that have opposing effects. In thermogenic brown and brite adipocytes, lipolysis stimulation is the canonical way for the activation of non-shivering thermogenesis. Lipolysis proceeds in an orderly and delicately regulated manner, with stimulation through cell-surface receptors via neurotransmitters, hormones, and autocrine/paracrine factors that activate various intracellular signal transduction pathways and increase kinase activity. The subsequent phosphorylation of perilipins, lipases, and cofactors initiates the translocation of key lipases from the cytoplasm to lipid droplets and enables protein-protein interactions to assemble the lipolytic machinery on the scaffolding perilipins at the surface of lipid droplets. Although activation of lipolysis has been well studied, the feedback fine-tuning is less well appreciated. This review focuses on the molecular brakes of lipolysis and discusses some of the divergent fine-tuning strategies in the negative feedback regulation of lipolysis, including delicate negative feedback loops, intermediary lipid metabolites-mediated allosteric regulation and dynamic protein–protein interactions. As aberrant adipocyte lipolysis is involved in various metabolic diseases and releasing the brakes on lipolysis in thermogenic adipocytes may activate thermogenesis, targeting adipocyte lipolysis is thus of therapeutic interest.

Differential effects of obesity on visceral versus subcutaneous adipose arteries: role of shear-activated Kir2.1 and alterations to the glycocalyx

Obesity imposes well-established deficits to endothelial function. We recently showed that obesity-induced endothelial dysfunction was mediated by disruption of the glycocalyx and a loss of Kir channel flow sensitivity. However, obesity-induced endothelial dysfunction is not observed in all vascular beds: visceral adipose arteries (VAAs), but not subcutaneous adipose arteries (SAAs), exhibit endothelial dysfunction. To determine whether differences in SAA versus VAA endothelial function observed in obesity are attributed to differential impairment of Kir channels and alterations to the glycocalyx, mice were fed a normal rodent diet, or a high-fat Western diet to induce obesity. Flow-induced vasodilation (FIV) was measured ex vivo. Functional downregulation of endothelial Kir2.1 was accomplished by transducing adipose arteries from mice and obese humans with adenovirus containing a dominant-negative Kir2.1 construct. Kir function was tested in freshly isolated endothelial cells seeded in a flow chamber for electrophysiological recordings under fluid shear. Atomic force microscopy was used to assess biophysical properties of the glycocalyx. Endothelial dysfunction was observed in VAAs of obese mice and humans. Downregulating Kir2.1 blunted FIV in SAAs, but had no effect on VAAs, from obese mice and humans. Obesity abolished Kir shear sensitivity in VAA endothelial cells and significantly altered the VAA glycocalyx. In contrast, Kir shear sensitivity was observed in SAA endothelial cells from obese mice and effects on SAA glycocalyx were less pronounced. We reveal distinct differences in Kir function and alterations to the glycocalyx that we propose contribute to the dichotomy in SAA versus VAA endothelial function with obesity.NEW & NOTEWORTHY We identified a role for endothelial Kir2.1 in the differences observed in VAA versus SAA endothelial function with obesity. The endothelial glycocalyx, a regulator of Kir activation by shear, is unequally perturbed in VAAs as compared with SAAs, which we propose results in a near complete loss of VAA endothelial Kir shear sensitivity and endothelial dysfunction. We propose that these differences underly the preserved endothelial function of SAA in obese mice and humans.

Obesity epidemic through the prism of evolutionary processes

Currently, obesity has become one of the most serious public health problems. It takes millions of lives worldwide every year due to its association with numerous diseases and leads to significant social and economic losses. It is generally accepted that obesity is the result of the interaction of genes and environment, and the predisposition to it lies in our evolutionary past. This review discusses the role of adipose tissue in human evolution, the factors specifying a person’s predisposition to obesity, the main hypotheses for obesity origin, and potential prevention and treatment strategies arising from them. The evolutionary significance of visceral adipose tissue and some ethnic and sex characteristics associated with its distribution are also considered.

Serum Resistin Levels and Related Genetic Variants Are Associated With Bone Mineral Density in Postmenopausal Women

BACKGROUND

Osteoporosis is a multifactorial disorder and a number of genetic variants or loci responsible for bone mineral density (BMD) have been identified. Resistin, a novel adipokine has diverse role in human body including its function in bone remodeling. The objective of this study was to see the association of serum resistin levels and related genetic variants (rs3931020, rs13144478) with BMD in postmenopausal females.

METHODS

This comparative analytical study was conducted on postmenopausal osteoporotic (n=101), osteopenic (n=77) and non-osteoporotic (n=74) females. For comparison and correlational analysis, Kruskal-Wallis test and Spearman's rho correlation were used respectively. Hardy-Weinberg equilibrium (HWE) was calculated by using Chi-square test (χ²).

RESULTS

There was significant difference in the serum levels of resistin (p <0.001), among the three groups. Significant negative correlation of resistin was observed with BMD at various sites. Serum resistin levels were significantly low in the rs3931020 AA homozygous genotype (p = 0.010), and significantly high in the rs13144478 AT heterozygous genotype (p = 0.020), BMD at all sites except left femoral neck was significantly high in rs3931020 AA genotype, while BMD at lumbar spine, left hip and total BMD were significantly low in the rs13144478 TT homozygotes.

CONCLUSION

High serum resistin levels are associated with low BMD and single nucleotide variation in rs3931020 and rs13144478 may lead to high serum resistin levels and low bone mineral density. Resistin can serve as a new genetic marker, potential therapeutic target and predictor of osteoporosis.

Apolipoprotein CIII Reduction Protects White Adipose Tissues against Obesity-Induced Inflammation and Insulin Resistance in Mice

Apolipoprotein CIII (apoCIII) is proinflammatory and increases in high-fat diet (HFD)-induced obesity and insulin resistance. We have previously shown that reducing apoCIII improves insulin sensitivity in vivo by complex mechanisms involving liver and brown adipose tissue. In this study the focus was on subcutaneous (SAT) and visceral (VAT) white adipose tissue (WAT). Mice were either given HFD for 14 weeks and directly from start also treated with antisense oligonucleotide (ASO) against apoCIII or given HFD for 10 weeks and HFD+ASO for an additional 14 weeks. Both groups had animals treated with inactive (Scr) ASO as controls and in parallel chow-fed mice were injected with saline. Preventing an increase or lowering apoCIII in the HFD-fed mice decreased adipocytes’ size, reduced expression of inflammatory cytokines and increased expression of genes related to thermogenesis and beiging. Isolated adipocytes from both VAT and SAT from the ASO-treated mice had normal insulin-induced inhibition of lipolysis compared to cells from Scr-treated mice. In conclusion, the HFD-induced metabolic derangements in WATs can be prevented and reversed by lowering apoCIII.

Cardiac-derived TGF-β1 confers resistance to diet-induced obesity through the regulation of adipocyte size and function

Regulation of organismal homeostasis in response to nutrient availability is a vital physiological process that involves inter-organ communication. Understanding the mechanisms controlling systemic cross-talk for the maintenance of metabolic health is critical to counteract diet-induced obesity. Here, we show that cardiac-derived transforming growth factor beta 1 (TGF-β1) protects against weight gain and glucose intolerance in mice subjected to high-fat diet. Secretion of TGF-β1 by cardiomyocytes correlates with the bioavailability of this factor in circulation. TGF-β1 prevents adipose tissue inflammation independent of body mass and glucose metabolism phenotypes, indicating protection from adipocyte dysfunction-driven immune cell recruitment. TGF-β1 alters the gene expression programs in white adipocytes, favoring their fatty acid oxidation and consequently increasing their mitochondrial oxygen consumption rates. Ultimately, subcutaneous and visceral white adipose tissue from cadiac-specific TGF-β1 transgenic mice fail to undergo cellular hypertrophy, leading to reduced overall adiposity during high-fat feeding. Thus, TGF-β1 is a critical mediator of heart-fat communication for the regulation of systemic metabolism.

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TGFb1 is secreted from the heart to alter systemic metabolism.

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TGFb1 protects from diet-induced obesity.

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TGFb1 increases mitochondrial basal respiration in white adipocytes.

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Cardiac-derived TGFb1 prevents adipose tissue inflammation.

The Effect of Magnesium Supplementation on Endothelial Function: A Randomised Cross-Over Pilot Study

Evidence supports an association between low magnesium (Mg) intake and coronary heart disease and between Mg intake and endothelial function. The aim of this study was to assess the effect of one week of Mg supplementation on endothelial function, assessed by flow mediated dilatation (FMD). Nineteen healthy men and women completed this cross-over pilot study in which participants were randomised to take an over-the-counter magnesium supplement for one week or to follow their usual diet. Weight, FMD and blood pressure (BP) were taken on completion of each intervention and 24 h urine collections and blood samples were taken to assess compliance. Baseline serum Mg was within normal range for all participants. Urinary Mg and urinary magnesium-creatinine ratio (Mg/Cr) significantly increased between interventions, (p = 0.03, p = 0.005, respectively). No significant differences in FMD or BP were found between the interventions. A significant negative correlation was seen between age and FMD (r = -0.496, p = 0.031). When adjusted for age, saturated fat was negatively associated with FMD (p = 0.045). One week of Mg supplementation did not improve FMD in a healthy population.