Preferential fat deposition in subcutaneous versus visceral depots is associated with insulin sensitivity

Adipose Tissue Dysfunction in Obesity: Role of Mineralocorticoid Receptor

The mineralocorticoid receptor (MR) acts as an essential regulator of blood pressure, volume status, and electrolyte balance. However, in recent decades, a growing body of evidence has suggested that MR may also have a role in mediating pro-inflammatory, pro-oxidative, and pro-fibrotic changes in several target organs, including the adipose tissue. The finding that MR is overexpressed in the adipose tissue of patients with obesity has led to the hypothesis that this receptor can contribute to adipokine dysregulation and low-grade chronic inflammation, alterations that are linked to the development of obesity-related metabolic and cardiovascular complications. Moreover, several studies in animal models have investigated the role of MR antagonists (MRAs) in preventing the metabolic alterations observed in obesity. In the present review we will focus on the potential mechanisms by which MR activation can contribute to adipose tissue dysfunction in obesity and on the possible beneficial effects of MRAs in this setting.

From an Apple to a Pear: Moving Fat around for Reversing Insulin Resistance

Type 2 diabetes (T2D) is a chronic condition where the body is resistant to insulin, leading to an elevated blood glucose state. Obesity is a main factor leading to T2D. Many clinical studies, however, have described a proportion of obese individuals who express a metabolically healthy profile, whereas some lean individuals could develop metabolic disorders. To study obesity as a risk factor, body fat distribution needs to be considered rather than crude body weight. Different individuals' bodies favor storing fat in different depots; some tend to accumulate more fat in the visceral depot, while others tend to store it in the femoral depot. This tendency relies on different factors, including genetic background and lifestyle. Consuming some types of medications can cause a shift in this tendency, leading to fat redistribution. Fat distribution plays an important role in the progression of risk of insulin resistance (IR). Apple-shaped individuals with enhanced abdominal obesity have a higher risk of IR compared to BMI-matched pear-shaped individuals, who store their fat in the gluteal-femoral depots. This is related to the different adipose tissue physiology between these two depots. In this review, we will summarize the recent evidence highlighting the underlying protective mechanisms in gluteal-femoral subcutaneous adipose tissues compared to those associated with abdominal adipose tissue, and we will revise the recent evidence showing antidiabetic drugs that impact fat distribution as they manage the T2D condition.

Metabolic (dysfunction)-associated fatty liver disease in individuals of normal weight

Metabolic (dysfunction)-associated fatty liver disease (MAFLD) affects up to a third of the global population; its burden has grown in parallel with rising rates of type 2 diabetes mellitus and obesity. MAFLD increases the risk of end-stage liver disease, hepatocellular carcinoma, death and liver transplantation and has extrahepatic consequences, including cardiometabolic disease and cancers. Although typically associated with obesity, there is accumulating evidence that not all people with overweight or obesity develop fatty liver disease. On the other hand, a considerable proportion of patients with MAFLD are of normal weight, indicating the importance of metabolic health in the pathogenesis of the disease regardless of body mass index. The clinical profile, natural history and pathophysiology of patients with so-called lean MAFLD are not well characterized. In this Review, we provide epidemiological data on this group of patients and consider overall metabolic health and metabolic adaptation as a framework to best explain the pathogenesis of MAFLD and its heterogeneity in individuals of normal weight and in those who are above normal weight. This framework provides a conceptual schema for interrogating the MAFLD phenotype in individuals of normal weight that can translate to novel approaches for diagnosis and patient care.

Hypertriglyceridemic-waist phenotype is strongly associated with cardiovascular risk factor clustering in Chinese adolescents

The early identification of predictors related to cardiovascular risk factor clustering (CVRFC) in adolescents can help prevent Cardiovascular disease. The hypertriglyceridemic-waist circumference (HTW) phenotype is considered a simple and useful indicator to identify cardiovascular disease. However, there is limited research on the relationship between the HTW phenotype and (CVRFC) in adolescents. It is unclear whether the HTW phenotype can identify early the risk of developing CVRFC in adolescents. The study aimed to examine the association of the HTW phenotype with CVRFC in adolescents. A total of 1478 adolescents aged 12–18 years were classified into normal waist circumference (WC) and normal triglyceride (TG) (NWNT, 66.4%), normal WC and high TG (HTG, 5.5%), enlarged WC and normal TG (EW, 22.2%) and enlarged WC and high TG (HTW, 5.8%). High TG was defined as TG ≥ 1.47 mmol/L and enlarged WC ≥ 90th percentile by gender and age. CVRFs in this study included elevated blood pressure (BP), impaired fasting glucose (IFG), high total cholesterol (TC), low high-density lipoprotein cholesterol (HDL-C), and high low-density lipoprotein cholesterol (LDL-C). CVRFC ≥ 2 or CVRFC ≥ 3 were defined as the presence of at least two or three cardiovascular risk factors. After adjustment for BMI, gender and age, the HTW phenotype increased the risk of CVRFC ≥ 2 and CVRFC ≥ 3 compared to the NTNW phenotype, OR and 95%CI were 2.40 (1.23–4.58) and 3.63 (1.49–8.86), respectively. After stratification by gender, similar results were found in boys, however, girls with the EW phenotype had a lower risk of CVRFC ≥ 2 and CVRFC ≥ 3 compared with the NTNW phenotype after adjustment for BMI and age. The area under the ROC curve was 0.698 (0.661–0.736) and 0.782 (0.725–0.840) when TG was combined with WC to detect cardiovascular risk factors clustering, which was better than BMI, WHtR, TG or WC alone. And similar results were obtained for both boys and girls when stratified by gender. These results revealed that different combinations of TG and WC levels are closely associated with cardiovascular risk factors clustering in both boys and girls, and TG combining WC performed better than BMI, WHtR, TG or WC alone in detecting cardiovascular risk factor clustering in adolescents.

Association between Obesity, Overweight, Elevated Waist Circumference, and Insulin Resistance Markers among Brazilian Adolescent Students

(1) Background: There is still controversy concerning the most effective and efficient strategy to identify insulin resistance in adolescents. We estimated the level of fasting insulin (fasting insulin equivalent, FIeq) that would replicate the strength of the associations of obesity, overweight, and waist circumference with two insulin resistance markers: triglyceride/high-density lipoprotein (TG/HDL) and triglyceride/glucose (TyG); (2) Methods: We studied approximately 38,000 adolescents aged 12 to 17 years, sampled from a multicenter Brazilian school-based survey, The Study of Cardiovascular Risk Factors in Adolescents (Portuguese acronym, ERICA), conducted in 2013–2014. Fasting insulin equivalents for adiposity variables were calculated by dividing the beta coefficient of each adiposity measure by the fasting insulin beta coefficient from linear regression analysis according to age (12–14, 15–17 years old) and sex, and adjusted by smoking, alcohol consumption, physical inactivity, sedentary behavior, socioeconomic status, and Tanner stage; (3) Results: The FIeqs for obesity were greater than those for overweight and elevated waist circumference for both TG/HDL and TyG in early adolescence. The FIeqs for elevated WC were greater than those for obesity and overweight in adolescents aged 15 to 17 years; (4) Conclusions: Our study suggests that WC measurements might be useful to identify adolescents with insulin resistance, particularly in late adolescence.

Obesity, Weight Gain, and Fluid Overload in Peritoneal Dialysis

Obesity is a global epidemic that has a complicated pathogenesis as well as impact on the outcome of peritoneal dialysis (PD) patients. In this review, the prevalence of obesity in incident PD patients as well as the phenomenon of new-onset glucose intolerance after PD will be reviewed. Published literature on the effect of obesity on the survival and incidence of cardiovascular disease in PD patients will be discussed. Particular emphasis would be put on literature that compared the impact of obesity on the outcome of hemodialysis and PD, and the confounding effect of dialysis adequacy. Next, the complex concept of obesity and its relevance for PD will be explored. The focus would be put on the methods of assessment and clinical relevance of central versus general obesity, as well as visceral versus subcutaneous adipose tissue. The relation between obesity and systemic inflammation, as well as the biological role of several selected adipokines will be reviewed. The confounding effects of metabolic syndrome and insulin resistance will be discussed, followed by the prevalence and prognostic impact of weight gain during the first few years of PD. The differences between weight gain due to fluid overload and accumulation of adipose tissue will be discussed, followed by the current literature on the change in body composition after patients are put on chronic PD. The methods of body composition will be reviewed, and the clinical relevance of individual body component (fluid, fat, muscle, and bone) will be discussed. The review will conclude by highlighting current gaps of knowledge and further research directions in this area.

Body fat and risk of all-cause mortality: a systematic review and dose-response meta-analysis of prospective cohort studies

BACKGROUND/OBJECTIVES

We aimed to evaluate the relationships between body fat percentage (BF%), fat mass (FM), fat mass index (FMI) and visceral (VAT) and subcutaneous adipose tissue (SAT) with risk of all-cause mortality.

METHODS

We did a systematic search in PubMed, Scopus, and Web of Science to June 2021. We selected prospective cohorts of the relationship between body fat with risk of all-cause mortality in the general population. We applied random-effects models to calculate the relative risks (RRs) and 95%CIs.

RESULTS

A total of 35 prospective cohort studies with 923,295 participants and 68,389 deaths were identified. The HRs of all-cause mortality for a 10% increment in BF were 1.11 (95%CI: 1.02, 1.20; I² = 93%, n = 11) in the general adult populations, and 0.92 (95%CI: 0.79, 1.06; I² = 76%, n = 7) in adults older than 60 years. The HRs were 1.06 (95%CI: 1.01, 1.12; I² = 86%, n = 10) for a 5 kg increment in FM, 1.11 (95%CI: 1.06, 1.16; I² = 79%, n = 7) for a 2 kg/m² increment in FMI, and 1.17 (95%CI: 1.03, 1.33; I² = 72%, n = 8) and 0.81 (0.66, 0.99; I² = 59%, n = 6) for a 1-SD increment in VAT and SAT, respectively. There was a J shaped association between BF% and FM and all-cause mortality risk, with the lowest risk at BF% of 25% and FM of 20 kg. In subgroup analyses, although there was little evidence of between-subgroup heterogeneity, the observed positive associations were more pronounced in studies which had a longer duration, excluded participants with prevalent cardiovascular disease and cancer at baseline, with adjustment for smoking or restricted to never smokers, and less pronounced in studies which adjusted for potential intermediates, suggesting an impact of reverse causation, confounding and over-adjustment in some of the studies.

CONCLUSIONS

Higher body fat content was related to a higher risk of mortality in a J shaped manner. Any future studies should further assess the impact of reverse causation and residual confounding on these associations.

REGISTRATION

PROSPERO (CRD42021240743).

Association of metabolic syndrome with TyG index and TyG-related parameters in an urban Chinese population: a 15-year prospective study

BACKGROUND

The metabolic syndrome (Mets) is a multiplex risk factor for atherosclerotic cardiovascular diseases. The aims of the study were to assess the association of the Mets with TyG index and TyG-related parameters in an urban Chinese population.

METHODS

The data were collected in 1992 and then again in 2007 from the same group of 590 individuals (363 males and 227 females) without Mets in 1992. The fasting lipid profile and blood glucose were measured. TyG index and related parameters were calculated, and Mets defined according to the harmonized criteria. The area under the curve (AUC) of receiver operating characteristic curves was used to evaluate TyG index and related parameters for their diagnostic ability to identify people with Mets. Odd ratios (OR) for Mets prediction were calculated using stepwise logistic regression analyses.

RESULTS

The incidence of Mets was 18.64% over the 15-year follow-up period.During 15 years' follow-up, TyG-waist to height ratio (TyG-WHtR) shows the largest AUC for Mets detection (0.686) followed by TyG-waist circumference (TyG-WC) (0.660), TyG-waist-to-hip ratio (TyG-WHpR) (0.564), and TyG index (0.556) in all participants. Gender analysis revealed that TyG-WHtR and TyG-WC have the largest AUC in both genders. TyG-WHtR significantly predicted Mets in all participants, with an unadjusted odds ratio of 5.63 (95% CI 3.23-9.83 P < 0.001). Associations remained significant after adjustment for smoking, drinking, physical exercise and components of Mets.

CONCLUSIONS

TyG-WHtR might be a strong and independent predictor for Mets in all participants in an urban Chinese population. TyG-related markers that combine obesity markers with TyG index are superior to other parameters in identifying Mets in both genders.

Impact of Obesity Phenotype on Central Aortic Hemodynamics and Arterial Stiffness in a Chinese Health Assessment Population

Background

This study aimed to explore the association between BMI and/or central obesity parameters and measures of arterial hemodynamics to assess the effect of obesity on function of large arteries.

Methods

Data was obtained from 634 subjects undergoing health assessment at Ruijin Hospital, Shanghai. Subjects were divided into 3 groups according to their Body Mass Index (BMI (kg/ m 2 ) < 24 normal, 24-28 overweight, ≥ 28 obese). In addition, central obesity was described by waist-hip ratio (WHR) and waist-height ratio (WHtR). Radial arterial waveforms and carotid-femoral pulse wave velocity (cf-PWV) were measured with the subjects recumbent. Central arterial pressures were measured by pulse wave analysis of the radial waveform calibrated to peripheral cuff systolic (PSP) and diastolic pressure (PDP) to obtain central systolic pressure (CSP), central diastolic pressure (CDP), central pulse pressure (CPP), central augmentation pressure (CAP), and central augmentation index (cAIx). Pulse pressure was determined from the ratio of peripheral (PPP) and central (CPP) pulse pressure (PPP/CPP).

Results

CAP and cAIx were lowest in the obese group (p < 0.01). Pressure amplification was significantly higher as BMI increased (p < 0.05). After adjusting for confounding factors, WC, WHtR and WHR were independent risk factors for cf-PWV ( β = 0.120, p = 0.001, β = 0.103, p = 0.004, β = 0.092, p = 0.013), When BMI, WC, WHtR, WHR were put into the stepwise linear regression model, only WC was an independent risk factor for cf-PWV ( β = 0.135, p < 0.001).

Conclusions

Central obesity (WC and WHR) measures may have greater predictive value for vascular stiffness than BMI. This possibility warrants further studies focused on arterial wave travel and its relationship with body fat distribution.

Relationship of American Heart Association's Life Simple 7, Ectopic Fat, and Insulin Resistance in 5 Racial/Ethnic Groups

BACKGROUND

The inverse association between ideal cardiovascular health (CVH) as measured by the American Heart Association's Life Simple 7 (LS7) and cardiovascular disease (CVD) incidence is well documented. However, research exploring the association between CVH and specific risk factors for cardiometabolic disease is sparse in diverse cohorts.

METHODS

This study included 7717 participants from the Mediators of Atherosclerosis in South Asians Living in America and the Multi-Ethnic Study of Atherosclerosis cohorts. We assigned each LS7 component a 0, 1, and 2 and summed these scores to derive an overall CVH score. Visceral, subcutaneous, and intermuscular fat area, pericardial fat volume, and hepatic fat attenuation were measured using noncontrast computed tomography. Multivariable linear regression was used to examine associations between CVH categories and each log-transformed ectopic fat depot, as well as the homeostatic assessment for insulin resistance (HOMA-IR).

RESULTS

In adjusted analysis, compared to those with ideal CVH, participants with poor CVH demonstrated 63.4% (95% CI, 54.3-73.0) higher visceral fat area, 84.0% (95% CI, 76.5-92.1) higher pericardial fat volume, 61.6% (95% CI, 50.7-73.2) higher subcutaneous fat area, and 40.6% (95% CI, 30.2-52.0) higher intermuscular fat area, and 15.1% (95% CI, 13.1-17.2) higher hepatic fat (all Ps < 0.001). Also, poor CVH was associated with 148.2% (95% CI, 131.1-166.7) higher HOMA-IR. We also found significant heterogeneity in the strengths of association by race/ethnicity for each ectopic fat depot.

CONCLUSION

Poor and intermediate CVH, as defined by LS7 metrics, were associated with significantly higher measures of ectopic fat and insulin resistance among individuals from 5 racial/ethnic groups.

Enhanced C/EBPβ function promotes hypertrophic versus hyperplastic fat tissue growth and prevents steatosis in response to high-fat diet feeding

Chronic obesity is correlated with severe metabolic and cardiovascular diseases as well as with an increased risk for developing cancers. Obesity is usually characterized by fat accumulation in enlarged – hypertrophic – adipocytes that are a source of inflammatory mediators, which promote the development and progression of metabolic disorders. Yet, in certain healthy obese individuals, fat is stored in metabolically more favorable hyperplastic fat tissue that contains an increased number of smaller adipocytes that are less inflamed. In a previous study, we demonstrated that loss of the inhibitory protein-isoform C/EBPβ-LIP and the resulting augmented function of the transactivating isoform C/EBPβ-LAP promotes fat metabolism under normal feeding conditions and expands health- and lifespan in mice. Here, we show that in mice on a high-fat diet, LIP-deficiency results in adipocyte hyperplasia associated with reduced inflammation and metabolic improvements. Furthermore, fat storage in subcutaneous depots is significantly enhanced specifically in LIP-deficient male mice. Our data identify C/EBPβ as a regulator of adipocyte fate in response to increased fat intake, which has major implications for metabolic health and aging.

Visceral Adipose Tissue and Non-alcoholic Fatty Liver Disease in Patients with Type 2 Diabetes

AIM

To explore the association of visceral adipose tissue (VAT) area and non-alcoholic fatty liver disease (NAFLD) in patients with type 2 diabetes mellitus (T2DM).

METHODS

This was a cross-sectional study comprising 100 patients with T2DM and 100 non-T2DM individuals, matched for age, sex, and body mass index (BMI). Transient elastography was used to assess hepatic steatosis and liver stiffness measurements (LSM). Controlled attenuation parameter (CAP) was used to quantify hepatic steatosis. To distinguish grades of hepatic steatosis, cutoff values were as follows: S1 ≥ 302, S2 ≥ 331, and S3 ≥ 337 dB/m. Moreover, VAT area was measured by dual-energy X-ray absorptiometry in accordance with validated protocols.

RESULTS

CAP score was significantly higher in participants with T2DM (294.61 ± 3.82 vs. 269.86 ± 3.86 dB/ m; P < 0.001). Furthermore, 42% of participants with T2DM had hepatic steatosis (S > S1: 302 dB/m), while this figure was 26% in non-T2DM group (P < 0.003). The mean liver stiffness measurement was also significantly higher in patients with T2DM (5.53 vs. 4.79 kPa; P < 0.001). VAT area was greater in patients with T2DM compared to non-T2DM individuals: 163.79 ± 47.98 cm² versus 147.49 ± 39.09 cm², P = 0.009. However, total and truncal fat mass were not different between the two groups. Age, BMI, waist circumference, ALT, CAP, and LSM were significantly associated with VAT area. BMI and VAT area were the important determinants of steatosis in both groups of participants with and without T2DM. Moreover, the VAT area was associated with the severity of hepatic steatosis and liver stiffness, independent of anthropometric measures of obesity.

CONCLUSION

VAT area is a major determinant of the severity of hepatic steatosis and liver stiffness in patient with T2DM.

Distinctive clinical and genetic features of lean vs overweight fatty liver disease using the UK Biobank

BACKGROUND

Lean NAFLD may differ from NAFLD found in overweight or obese patients. We used the UK biobank to conduct a cross-sectional study that examined features that distinguish lean NAFLD from overweight or obese NAFLD.

METHODS

MRI-PDFF data were used to identify patients with NAFLD, with NAFLD defined as PDFF ≥ 5%. BMI patient cohorts were identified, with lean defined as a BMI < 25, and overweight or obese defined as a BMI ≥ 25. Variables of interest to fatty liver disease, including single nucleotide polymorphisms, were chosen from the UK biobank data portal. Logistic regression was used to generate models predictive of NAFLD in each cohort.

RESULTS

1007 patients had NAFLD, and of these, 871 had BMI ≥ 25, and 136 BMI < 25. Factors associated with NAFLD in patients with BMI < 25 included male sex, white blood cell count, red blood cell count, triglycerides, ALT, creatinine, visceral adipose tissue, rs58542926 T, and rs738409 G. In contrast, factors associated with NAFLD in patients with BMI ≥ 25 included male sex, waist circumference, HDL cholesterol, triglycerides, serum glucose, ALT, creatinine, urate, visceral adipose tissue, rs1260326 T, rs1044498 C, rs58542926 T, and rs738409 G. For lean patients, our generated prediction score had an AUC of 0.92, sensitivity of 0.90 and specificity of 0.81. For overweight or obese patients, the prediction score had an AUC of 0.86, sensitivity of 0.87 and specificity of 0.70.

CONCLUSIONS

Our analysis suggests that lean and overweight or obese NAFLD are distinct entities. We have developed a risk score incorporating both clinical and genetic factors that accurately classify lean patients with NAFLD, with the potential to serve as a tool for screening purposes.

Functions and origins of cardiac fat

Triglyceride droplets can be stored within cardiac adipocytes (CAs) and cardiomyocytes in the heart. Cardiac adipocytes reside in three distinct regions: pericardial, epicardial, and intramyocardial adipose tissues. In healthy individuals, cardiac adipose tissues modulate cardiovascular functions and energy partitioning, which are, thus, protective. However, ectopic deposition of cardiac adipose tissues turns them into adverse lipotoxic, prothrombotic, and pro-inflammatory tissues with local and systemic contribution to the development of cardiovascular disorders. Accumulation of triglyceride droplets in cardiomyocytes may lead to lipotoxic injury of cardiomyocytes and contribute to the development of cardiac hypertrophy and dysfunction. Here, we summarize the roles of CAs and myocardial triglyceride droplets under physiological and pathological conditions and review the cellular sources of CAs in heart development and diseases. Understanding the functions and cellular origins of cardiac fat will provide clues for future studies on pathophysiological processes and treatment of cardiovascular diseases.

Polycystic Ovary Syndrome: An Evolutionary Adaptation to Lifestyle and the Environment

Polycystic ovary syndrome (PCOS) is increasingly recognized as a complex metabolic disorder that manifests in genetically susceptible women following a range of negative exposures to nutritional and environmental factors related to contemporary lifestyle. The hypothesis that PCOS phenotypes are derived from a mismatch between ancient genetic survival mechanisms and modern lifestyle practices is supported by a diversity of research findings. The proposed evolutionary model of the pathogenesis of PCOS incorporates evidence related to evolutionary theory, genetic studies, in utero developmental epigenetic programming, transgenerational inheritance, metabolic features including insulin resistance, obesity and the apparent paradox of lean phenotypes, reproductive effects and subfertility, the impact of the microbiome and dysbiosis, endocrine-disrupting chemical exposure, and the influence of lifestyle factors such as poor-quality diet and physical inactivity. Based on these premises, the diverse lines of research are synthesized into a composite evolutionary model of the pathogenesis of PCOS. It is hoped that this model will assist clinicians and patients to understand the importance of lifestyle interventions in the prevention and management of PCOS and provide a conceptual framework for future research. It is appreciated that this theory represents a synthesis of the current evidence and that it is expected to evolve and change over time.

High Visceral Fat in Female Breast Cancer Patients Correlates with the Risk of Progression after Adjuvant Chemotherapy

RATIONALE

Clinical and epidemiological evidence indicate that obesity is associated with the risk and progression of breast cancer. Body mass index (BMI) as a measure of adiposity does not precisely describe individual body composition and adipose tissue distribution. We aimed to investigate the association between body composition and the efficiency of adjuvant chemotherapy as well as post-treatment progress among female breast cancer patients.

METHODS

Participants included 199 females with stage I-III breast cancer. Body composition, including body fat mass, visceral fat level, and skeletal muscle mass, was assessed based on the bioelectrical impedance analysis (BIA). The Kaplan-Meier survival curves, log-rank test, and Cox proportional-hazards model were used to estimate the effects of body composition as prognostic factors on survival.

RESULTS

Postmenopausal women had a higher proportion of visceral fat compared to premenopausal women (64% vs. 33.87%, P < 0.001). Compared with those with normal visceral fat level, patients with high visceral fat level were older (P < 0.001), had higher body fat mass (p < 0.001), skeletal muscle mass (P = 0.013), minerals (P = 0.011), protein (P = 0.036), triglycerides (P = 0.038), cholesterol (P = 0.022), and low-density lipoprotein cholesterol (LDL-C) (P = 0.015). A more prolonged disease-free survival (DFS) was noted in patients with a normal visceral fat level as compared to patients with a high visceral fat level (hazard ratio [HR] 1.9, 95% CI 1-3.5; adjusted HR 1.77, 95% CI 0.932-3.36).

CONCLUSIONS

A high visceral fat level in female patients with breast cancer is associated with a shorter DFS after adjuvant chemotherapy. Body composition alongside BIA provides a quick and noninvasive approach to identify breast cancer patients with a higher risk of cancer progression.

Polycystic ovary syndrome as a plausible evolutionary outcome of metabolic adaptation

As a common endocrinopathy of reproductive-aged women, polycystic ovary syndrome (PCOS) is characterized by hyperandrogenism, oligo-anovulation and polycystic ovarian morphology. It is linked with insulin resistance through preferential abdominal fat accumulation that is worsened by obesity. Over the past two millennia, menstrual irregularity, male-type habitus and sub-infertility have been described in women and confirm that these clinical features of PCOS were common in antiquity. Recent findings in normal-weight hyperandrogenic PCOS women show that exaggerated lipid accumulation by subcutaneous (SC) abdominal stem cells during development to adipocytes in vitro occurs in combination with reduced insulin sensitivity and preferential accumulation of highly-lipolytic intra-abdominal fat in vivo. This PCOS phenotype may be an evolutionary metabolic adaptation to balance energy storage with glucose availability and fatty acid oxidation for optimal energy use during reproduction. This review integrates fundamental endocrine-metabolic changes in healthy, normal-weight PCOS women with similar PCOS-like traits present in animal models in which tissue differentiation is completed during fetal life as in humans to support the evolutionary concept that PCOS has common ancestral and developmental origins.

The beneficial metabolic actions of prolactin

The role of prolactin (PRL) favoring metabolic homeostasis is supported by multiple preclinical and clinical studies. PRL levels are key to explaining the direction of its actions. In contrast with the negative outcomes associated with very high (>100 μg/L) and very low (<7 μg/L) PRL levels, moderately high PRL levels, both within but also above the classically considered physiological range are beneficial for metabolism and have been defined as HomeoFIT-PRL. In animal models, HomeoFIT-PRL levels counteract insulin resistance, glucose intolerance, adipose tissue hypertrophy and fatty liver; and in humans associate with reduced prevalence of insulin resistance, fatty liver, glucose intolerance, metabolic syndrome, reduced adipocyte hypertrophy, and protection from type 2 diabetes development. The beneficial actions of PRL can be explained by its positive effects on main metabolic organs including the pancreas, liver, adipose tissue, and hypothalamus. Here, we briefly review work supporting PRL as a promoter of metabolic homeostasis in rodents and humans, the PRL levels associated with metabolic protection, and the proposed mechanisms involved. Finally, we discuss the possibility of using drugs elevating PRL for the treatment of metabolic diseases.

Obesity, Adipose Tissue, and Inflammation Answered in Questions

Background. Obesity is a global health problem of epidemic proportions, which is characterized by increased adipose tissue (AT) mass and significant repercussions in different body apparati and systems. AT is a special connective tissue, which contains several types of cells, in addition to adipocytes, and is a highly active endocrine and immune organ, which directly modulates many processes, including energy balance, metabolism, and inflammation. Summary. In this paper, the authors list and attempt to answer in a brief and simple way several questions regarding the complex relationships between obesity, adipose tissue, and inflammation, with the objective to provide an easy way to understand the main changes that occur in this pathological state. The questions are the following: Is adipose tissue only made up of adipocytes? Are adipocytes just a reservoir of free fatty acids? Do different types of fatty tissue exist? If so, which types? Can we further subcategorize the types of adipose tissue? Is it possible to form new adipocytes during adulthood? What is the role of inflammation? What is the role of macrophages? Are macrophages central mediators of obesity-induced adipose tissue inflammation and insulin resistance? What causes macrophage infiltration into adipose tissue? What is the role of hypoxia in AT alterations? Is there cross talk between adipocytes and immune cells? What other changes occur in AT in obesity? Does metabolically healthy obesity really exist? Is this a benign condition? Key messages. Obesity is a complex disease with numerous metabolic consequences, which are mainly the result of dysfunction that occurs in the adipose tissue of patients with this pathology. Understanding the pathophysiology of AT and the changes that occur in obesity would contribute to a better approach to patients with obesity, with the inherent medical implications that could result from this.

Diabetic yoga protocol improves glycemic, anthropometric and lipid levels in high risk individuals for diabetes: a randomized controlled trial from Northern India

PURPOSE

To study the effectiveness of diabetic yoga protocol (DYP) against management of cardiovascular risk profile in a high-risk community for diabetes, from Chandigarh, India.

METHODS

The study was a randomized controlled trial, conducted as a sub study of the Pan India trial Niyantrita Madhumeha Bharath (NMB). The cohort was identified through the Indian Diabetes Risk Scoring (IDRS) (≥ 60) and a total of 184 individuals were randomized into intervention (n = 91) and control groups (n = 93). The DYP group underwent the specific DYP training whereas the control group followed their daily regimen. The study outcomes included changes in glycemic and lipid profile. Analysis was done under intent-to-treat principle.

RESULTS

The 3 months DYP practice showed diverse results showing glycemic and lipid profile of the high risk individuals. Three months of DYP intervention was found to significantly reduce the levels of post-prandial glucose levels (p = 0.035) and LDL-c levels (p = 0.014) and waist circumference (P = 0.001).

CONCLUSION

The findings indicate that the DYP intervention could improve the metabolic status of the high-diabetes-risk individuals with respect to their glucose tolerance and lipid levels, partially explained by the reduction in abdominal obesity. The study highlights the potential role of yoga intervention in real time improvement of cardiovascular profile in a high diabetes risk cohort.

TRIAL REGISTRATION

CTRI, CTRI/2018/03/012804. Registered 01 March 2018-Retrospectively registered, http://www.ctri.nic.in/ CTRI/2018/03/012804.

Exploring Obesity as a Gendered Contagion: Impact on Lifestyle Interventions to Improve Cardiovascular Health

PURPOSE

Obesity increases the risk of cardiovascular disease. Lifestyle interventions such as physical activity and diet are important components for reducing the risk of obesity. Data suggest that lifestyle choices differ between men and women, as well as in groups. The purpose of this review was to explore whether obesity can be considered as a gendered social contagion, associated with differences in lifestyle and response to lifestyle interventions in men and women.

FINDINGS

There are important sex-based differences of obesity to consider. There is evidence that peers have an influence on lifestyle preferences such as physical activity level and dietary habits, but the evidence is inconclusive if the differences exist between men and women. Similarly, data from lifestyle intervention studies are not conclusive whether there are differences between men and women. There is not enough evidence for the notion that obesity is a gendered social contagion.

IMPLICATIONS

More research is needed to understand differences in lifestyle and lifestyle interventions between men and women, especially across the life span, which could have profound public health implications.

Gender difference in the relationship between lipid accumulation product index and pulse pressure in nondiabetic Korean adults: The Korean National Health and Nutrition Examination Survey 2013-2014

The present study was conducted to assess the association between the lipid accumulation product index (LAP) and pulse pressure (PP) by gender in nondiabetic Korean adults. This study used the data of 8,240 nondiabetic adults (3,577 men and 4,663 women) aged ≥ 20 years from the Korean National Health and Nutrition Examination Survey 2013-2014. Key findings from the study were as follows: first, the mean values of age for the overall population, men, and women were 49.59 ± 15.73 years, 49.26 ± 16.04 years, and 49.85 ± 15.47 years, respectively. Second, in women (n = 4,663), after adjustment for related variables and with quartile 1 of LAP as a reference, the odds ratios (ORs) of high PP (PP > 60 mmHg) were significantly higher in quartile 3 [1.735 (95% confidence interval [CI], 1.064-2.831)] and quartile 4 of LAP [2.271 (95% CI, 1.325-3.893)]. Third, high PP in men (n = 3,577) was not associated with the quartiles of LAP. Forth, after adjustment for related variables, the PP level was positively associated with the quartiles of LAP in women (p < .001) but not in men (p = .400). PP was positively associated with LAP in nondiabetic Korean women but not in men.

Cutoff point of TyG index for metabolic syndrome in Brazilian farmers

OBJECTIVE

Thus, the aim of this study was to identify the cutoff point of the TyG index for the diagnosis of insulin resistance (IR), according to two different diagnostic criteria of metabolic syndrome in a rural Brazilian population.

METHODS

The study population consisted of 790 family farmers from 18 to 59 years old. The triglyceride-glucose index (TyG index) was calculated, and the Metabolic Syndrome was defined using the NCEP-ATPIII and IDF criteria. Mann-Whitney U test was used to analyze the association of quantitative and qualitative variables. When the qualitative variable had three or more categories, the comparison between the means was performed by the Kruskal-Wallis test (using the Mann-Whitney U Test two by two to identify the differences). For correlations, Spearman's correlation test was used. The cutoff values of TyG index for MetS were obtained using the Receiver Operating Characteristic (ROC) curve analysis with the area under the curve (AUC) and the Youden Index.

RESULTS

The median TyG values increased according to the aggregation of the components of MetS. The AUCs and Youden's cutoff point for TyG index according to the NCEP and IDF diagnostic criteria were 0.873, Ln 4.52 (sensitivity: 84.30%; specificity: 75.75%), and 0.867, Ln 4.55 (sensitivity: 80.0%; specificity: 79.82%), respectively.

CONCLUSION

A cutoff point of Ln 4.52 was defined, and it can be used both in clinical practice and epidemiological studies. It represents an important tool for promotion, protection and recovery health of rural populations.

Detection of diabetes from whole-body MRI using deep learning

Obesity is one of the main drivers of type 2 diabetes, but it is not uniformly associated with the disease. The location of fat accumulation is critical for metabolic health. Specific patterns of body fat distribution, such as visceral fat, are closely related to insulin resistance. There might be further, hitherto unknown, features of body fat distribution that could additionally contribute to the disease. We used machine learning with dense convolutional neural networks to detect diabetes-related variables from 2371 T1-weighted whole-body MRI data sets. MRI was performed in participants undergoing metabolic screening with oral glucose tolerance tests. Models were trained for sex, age, BMI, insulin sensitivity, HbA1c, and prediabetes or incident diabetes. The results were compared with those of conventional models. The area under the receiver operating characteristic curve was 87% for the type 2 diabetes discrimination and 68% for prediabetes, both superior to conventional models. Mean absolute regression errors were comparable to those of conventional models. Heatmaps showed that lower visceral abdominal regions were critical in diabetes classification. Subphenotyping revealed a group with high future diabetes and microalbuminuria risk.Our results show that diabetes is detectable from whole-body MRI without additional data. Our technique of heatmap visualization identifies plausible anatomical regions and highlights the leading role of fat accumulation in the lower abdomen in diabetes pathogenesis.

Serum Testosterone to Androstenedione Ratio Predicts Metabolic Health in Normal-Weight Polycystic Ovary Syndrome Women

Context

Increased aldo-keto reductase 1C3 (AKR1C3)-mediated conversion of androstenedione (A4) to testosterone (T) promotes lipid storage in subcutaneous (SC) abdominal adipose in overweight/obese polycystic ovary syndrome (PCOS) women.

Objective

This work examines whether an elevated serum T/A4 ratio, as a marker of enhanced AKR1C3 activity in SC abdominal adipose, predicts metabolic function in normal-weight PCOS women.

Methods

This prospective cohort study took place in an academic center and comprised 19 normal-weight PCOS women and 21 age- and body mass index–matched controls. Interventions included circulating hormone/metabolic determinations, intravenous glucose tolerance testing, total body dual-energy x-ray absorptiometry, and SC abdominal fat biopsy. Serum T/A4 ratios, hormone/metabolic measures, and AKR1C3 expression of adipocytes matured in vitro were compared between female types; serum T/A4 ratios were correlated with serum lipids, adipose insulin resistance (adipose-IR), homeostatic model assessment of insulin resistance (HOMA-IR) and insulin sensitivity (Si).

Results

Increased serum T/A4 ratios (P = .040) and log adipose-IR values (P = .002) in PCOS women vs controls were accompanied by AKR1C3 messenger RNA overexpression of PCOS adipocytes matured in vitro (P = .016). Serum T/A4 ratios in PCOS women, but not controls, negatively correlated with log triglycerides (TGs: R = –0.65, P = .002) and the TG index (R = –0.57, P = .011). Adjusting for serum free T, serum T/A4 ratios in PCOS women remained negatively correlated with log TG (R = –0.57, P = .013) and TG index (R = –0.50, P = .036), respectively, without significant relationships with other metabolic measures.

Conclusion

An elevated serum T/A4 ratio, as a marker of enhanced AKR1C3 activity in SC abdominal adipose, predicts healthy metabolic function in normal-weight PCOS women.

Distinct opposing associations of upper and lower body fat depots with metabolic and cardiovascular disease risk markers

BACKGROUND

To examine the associations of total and regional adiposity with metabolic and cardiovascular disease (CVD) risk markers.

METHODS

This cross-sectional study included 1080 (53.8% men, aged 39-44 years) individuals from South India. Anthropometry (height, weight, waist and hip circumference), body composition assessment using dual-energy X-ray absorptiometry (DXA), blood pressure (BP), and plasma glucose, insulin and lipids were measured. Regression analysis was used to examine associations of standardized fat measurements with type 2 diabetes (T2D), insulin resistance (IR), hypertension and hypertriglyceridemia and continuous measurements of BP, glucose, insulin, HOMA-IR and lipids. Contour plots were constructed to visualize the differential effect of upper and lower fat depots.

RESULTS

DXA-measured fat depots were positively associated with metabolic and CVD risk markers. After adjusting for fat mass index, upper body fat remained positively, while lower body fat was negatively associated with risk markers. A one standard deviation (SD) increase in android fat showed higher odds ratios (ORs) for T2D (6.59; 95% CI 3.17, 13.70), IR (4.68; 95% CI 2.31, 9.50), hypertension (2.57; 95% CI 1.56, 4.25) and hypertriglyceridemia (6.39; 95% CI 3.46, 11.90) in men. A 1 SD increase in leg fat showed a protective effect with ORs for T2D (0.42; 95% CI 0.24, 0.74), IR (0.31; 95% CI 0.17, 0.57) and hypertriglyceridemia (0.61; 95% CI 0.38, 0.98). The magnitude of the effect was greater with DXA-measured fat compared with anthropometry.

CONCLUSION

At any level of total body fat, upper and lower body fat depots demonstrate opposite risk associations with metabolic and CVD risk markers in Asian Indians.

The Effect of Weight-Loss Interventions on Cervical and Chin Subcutaneous Fat Depots; the CENTRAL Randomized Controlled Trial

Accumulation of cervical and chin subcutaneous adipose tissues (SAT) represent known phenotypes of obesity. We aimed to evaluate the sensitivity of these fat storages to long-term weight-loss directed lifestyle-intervention and to assess their relations to bodily-adiposity, insulin-resistance, and cardiometabolic risk; We randomly assigned 278 participants with abdominal-obesity/dyslipidemia to low-fat or Mediterranean/low-carbohydrate diets +/- physical-activity. All participants underwent an 18 month whole-body magnetic resonance imaging follow-up, from which we assessed cervical and chin SAT-areas; Participants (age = 48 years; 90% men; body-mass-index = 30.9 kg/m²) had an 18-month adherence-rate of 86%. Cervical-SAT and chin-SAT decreased after 6-months (-13.1% and -5.3%, respectively, p < 0.001). After 18-months only cervical-SAT remained decreased compared to baseline (-5%, p < 0.001). Cervical and chin-SAT 18-month changes were associated with changes in weight (r = 0.70, r = 0.66 respectively; <0.001 for both) and visceral-adipose-tissue (VAT; r = 0.35, r = 0.42 respectively; <0.001 for both). After adjustment to VAT, waist-circumference, or weight-changes, chin-SAT 18-month reduction was associated with favorable changes in fasting-glucose (β = 0.10; p = 0.05), HbA1c (β = 0.12; p = 0.03), and homeostasis-model-assessment-of-insulin-resistance (β = 0.12; p = 0.03). Cervical-SAT 18-month reduction was associated with decreased triglycerides (β = 0.16; p = 0.02) and leptin (β = 0.19; p = 0.01) independent of VAT; Cervical and chin-SATs are dynamic fat depots that correspond with weight-loss and are associated with changes in cardiometabolic profile. In long-term, chin-SAT displays a larger rebound compared with cervical-SAT. Chin-SAT accumulation is associated with in insulin-resistance, independent of central obesity. (ClinicalTrials identifier NCT01530724).

EH Domain-Containing 2 Deficiency Restricts Adipose Tissue Expansion and Impairs Lipolysis in Primary Inguinal Adipocytes

Lipid uptake can be facilitated via caveolae, specific plasma membrane invaginations abundantly expressed in adipocytes. The dynamin-related protein EH domain-containing 2 (EHD2) stabilizes caveolae at the cell surface. Here, we have examined the importance of EHD2 for lipid handling using primary adipocytes isolated from EHD2 knockout (Ehd2^−/−) C57BL6/N mice. Following high-fat diet (HFD) feeding, we found a clear impairment of epididymal, but not inguinal, adipose tissue expansion in Ehd2^−/− compared with Ehd2^+/+ (WT) mice. Cell size distribution analysis revealed that Ehd2^−/− mice had a lower proportion of small adipocytes, and an accumulation of medium-sized adipocytes in both epididymal and inguinal adipose tissue. Further, PPARγ activity, FABP4 and caveolin-1 expression were decreased in adipocytes isolated from Ehd2^−/− mice. Inguinal adipocytes isolated from Ehd2^−/− mice displayed reduced lipolysis in response to beta adrenergic receptor agonist, which was associated with reduced phosphorylation of perilipin-1 and hormone sensitive lipase (HSL). This impairment could not be rescued using a cAMP analog, indicating that impaired lipolysis in Ehd2^−/− primary adipocytes likely occurs at the level of, or downstream of, protein kinase A (PKA). Altogether, these findings pinpoint the importance of EHD2 for maintained intracellular lipid metabolism, and emphasize differences in mechanisms regulating lipid handling in various adipose-tissue depots.

Metformin alleviates stress-induced cellular senescence of aging human adipose stromal cells and the ensuing adipocyte dysfunction

Aging is associated with central fat redistribution and insulin resistance. To identify age-related adipose features, we evaluated the senescence and adipogenic potential of adipose-derived stromal cells (ASCs) from abdominal subcutaneous fat obtained from healthy normal-weight young (<25 years) or older women (>60 years). Increased cell passages of young-donor ASCs (in vitro aging) resulted in senescence but not oxidative stress. ASC-derived adipocytes presented impaired adipogenesis but no early mitochondrial dysfunction. Conversely, aged-donor ASCs at early passages displayed oxidative stress and mild senescence. ASC-derived adipocytes exhibited oxidative stress, and early mitochondrial dysfunction but adipogenesis was preserved. In vitro aging of aged-donor ASCs resulted in further increased senescence, mitochondrial dysfunction, oxidative stress, and severe adipocyte dysfunction. When in vitro aged young-donor ASCs were treated with metformin, no alteration was alleviated. Conversely, metformin treatment of aged-donor ASCs decreased oxidative stress and mitochondrial dysfunction resulting in decreased senescence. Metformin's prevention of oxidative stress and of the resulting senescence improved the cells' adipogenic capacity and insulin sensitivity. This effect was mediated by the activation of AMP-activated protein kinase as revealed by its specific inhibition and activation. Overall, aging ASC-derived adipocytes presented impaired adipogenesis and insulin sensitivity. Targeting stress-induced senescence of ASCs with metformin may improve age-related adipose tissue dysfunction.

Lipid Accumulation Product as an Index for Visceral Obesity and Cardiovascular Risk among a Sample of Obese Egyptian Women

Background:Lipid accumulation product (LAP) is one of the indices that can demonstrate cardiovascularrisk factors according to international studies. Aim: To evaluate relationship between LAP, visceral obesity and different cardio vascular risk factors among sample of obese Egyptian Women. Methods: A retrospective cross-sectional observational study included 350 obese Egyptian women; aged 25- 55 years. They were subjected to blood pressure and anthropometric assessment (weight, height and waist circumference), abdominal ultrasound (visceral fat) and laboratory tests (fasting blood sugar and lipid profile).Results: The majority of the participated women had wide WC (88.9%) and increased visceral fat (80.6%). Hyperglycemia was present among (47.4%), hypertension among 42.6%, high triglycerides among 26.6% and low HDL among 44.3%. The odds of obtaining LAP >80.74 cm.mmol/L (4th quartile) is 2.7 times higher in individuals with hypertension(BP > 130/85),and 6.79 times higher in individuals with visceral fat ≥ 5 cm. Depending on the visceral fat as a standard for classification of visceral obesity (>5 cm for women), revealed that the AUCs of LAP was 0.752 (95% CI 0.697–0.806) in women. The cutoff point of LAP;for prediction of visceral obesity among Egyptian women, was 61.69; using ROC analysis; with sensitivity 68% and specificity 75% and PPV/NPV 1.05 and accuracy 71.5% .Conclusion: LAP index had significant correlations with visceral obesity and hypertension. The cutoff point of LAP 61.69 can be used to predict visceral obesity among Egyptian women.

Free fatty acids, glicentin and glucose-dependent insulinotropic polypeptide as potential major determinants of fasting substrate oxidation

The selection of carbohydrates or fat to generate intracellular energy is thought to be crucial for long-term metabolic health. While most studies assess fuel selection after a metabolic challenge, the determinants of substrate oxidation in the fasted state remain largely unexplored. We therefore assessed the respiratory quotient by indirect calorimetry as a read-out for substrate oxidation following an overnight fast. This cross-sectional analysis consisted of 192 (92 women, 100 men) either lean or obese participants. Following an overnight fast, the respiratory quotient (RQ) was assessed, after which a 5-point 75-g oral glucose tolerance test was performed. Unlike glucose and insulin, fasting free fatty acids (FFA) correlated negatively with fasting RQ (p < 0.0001). Participants with high levels of the ketone body β-hydroxybutyric acid had significantly lower RQ values. Fasting levels of glucose-dependent insulinotropic polypeptide (GIP) and glicentin were positively associated with fasting RQ (all p ≤ 0.03), whereas GLP-1 showed no significant association. Neither BMI, nor total body fat, nor body fat distribution correlated with fasting RQ. No relationship between the RQ and diabetes or the metabolic syndrome could be observed. In the fasting state, FFA concentrations were strongly linked to the preferentially oxidized substrate. Our data did not indicate any relationship between fasting substrate oxidation and metabolic diseases, including obesity, diabetes, and the metabolic syndrome. Since glicentin and GIP are linked to fuel selection in the fasting state, novel therapeutic approaches that target these hormones may have the potential to modulate substrate oxidation.

White adipose tissue dysfunction in obesity and aging

Both obesity and aging are associated with the development of metabolic diseases such as type 2 diabetes and cardiovascular disease. Chronic low-grade inflammation of adipose tissue is one of the mechanisms implicated in the progression of these diseases. Obesity and aging trigger adipose tissue alterations that ultimately lead to a pro-inflammatory phenotype of the adipose tissue-resident immune cells. Obesity and aging also share other features such as a higher visceral vs. subcutaneous adipose tissue ratio and a decreased lifespan. Here, we review the common characteristics of obesity and aging and the alterations in white adipose tissue and resident immune cells. We focus on the adipose tissue metabolic derangements in obesity and aging such as inflammation and adipose tissue remodeling.

Fat-enlarged axillary lymph nodes are associated with node-positive breast cancer in obese patients

PURPOSE

Obesity associated fat infiltration of organ systems is accompanied by organ dysfunction and poor cancer outcomes. Obese women demonstrate variable degrees of fat infiltration of axillary lymph nodes (LNs), and they are at increased risk for node-positive breast cancer. However, the relationship between enlarged axillary nodes and axillary metastases has not been investigated. The purpose of this study is to evaluate the association between axillary metastases and fat-enlarged axillary nodes visualized on mammograms and breast MRI in obese women with a diagnosis of invasive breast cancer.

METHODS

This retrospective case-control study included 431 patients with histologically confirmed invasive breast cancer. The primary analysis of this study included 306 patients with pre-treatment and pre-operative breast MRI and body mass index (BMI) > 30 (201 node-positive cases and 105 randomly selected node-negative controls) diagnosed with invasive breast cancer between April 1, 2011, and March 1, 2020. The largest visible LN was measured in the axilla contralateral to the known breast cancer on breast MRI. Multivariate logistic regression models were used to assess the association between node-positive status and LN size adjusting for age, BMI, tumor size, tumor grade, tumor subtype, and lymphovascular invasion.

RESULTS

A strong likelihood of node-positive breast cancer was observed among obese women with fat-expanded lymph nodes (adjusted OR for the 4th vs. 1st quartile for contralateral LN size on MRI: 9.70; 95% CI 4.26, 23.50; p < 0.001). The receiver operating characteristic curve for size of fat-enlarged nodes in the contralateral axilla identified on breast MRI had an area under the curve of 0.72 for predicting axillary metastasis, and this increased to 0.77 when combined with patient and tumor characteristics.

CONCLUSION

Fat expansion of axillary lymph nodes was associated with a high likelihood of axillary metastases in obese women with invasive breast cancer independent of BMI and tumor characteristics.

Differences in Abdominal Body Composition According to Glycemic Status: An Inverse Probability Treatment Weighting Analysis

BACKGROUND

Several studies have reported that abdominal fat and muscle changes occur in diabetic patients. However, there are few studies about such changes among prediabetic patients. In this study, we evaluated the differences in abdominal fat and muscles based on abdominopelvic computed tomography in prediabetic and diabetic subjects compared to normal subjects.

METHODS

We performed a cross-sectional study using health examination data from March 2014 to June 2019 at Ulsan University Hospital and classified subjects into normal, prediabetic, and diabetic groups. We analyzed the body mass index corrected area of intra-abdominal components among the three groups using inverse probability treatment weighting (IPTW) analysis.

RESULTS

Overall, 8,030 subjects were enrolled; 5,137 (64.0%), 2,364 (29.4%), and 529 (6.6%) subjects were included in the normal, prediabetic, and diabetic groups, respectively. After IPTW adjustment of baseline characteristics, there were significant differences in log visceral adipose tissue index (VATI; 1.22±0.64 cm2/[kg/m2] vs. 1.30±0.63 cm2/[kg/m2] vs. 1.47±0.64 cm2/[kg/m2], P<0.001) and low-attenuation muscle index (LAMI; 1.02±0.36 cm2/[kg/m2] vs. 1.03±0.36 cm2/[kg/m2] vs. 1.09±0.36 cm2/[kg/m2], P<0.001) among the normal, prediabetic, and diabetic groups. Prediabetic subjects had higher log VATI (estimated coefficient= 0.082, P<0.001), and diabetic subjects had higher log VATI (estimated coefficient=0.248, P<0.001) and LAMI (estimated coefficient=0.078, P<0.001) compared to normal subjects.

CONCLUSION

Considering that VATI and LAMI represented visceral fat and lipid-rich skeletal muscle volumes, respectively, visceral obesity was identified in both prediabetic and diabetic subjects compared to normal subjects in this study. However, intra-muscular fat infiltration was observed in diabetic subjects only.

Obesity activates immunomodulating properties of mesenchymal stem cells in adipose tissue with differences between localizations

Mesenchymal stem cells from healthy adipose tissue are adipocytes progenitors with immunosuppressive potential that are used for years in cell therapy. Whether adipose stem cells (ASC) may prevent inflammation in early obesity is not known. To address this question, we performed a kinetic study of high-fat (HF) diet induced obesity in mice to follow the immune regulating functions of adipose stem cells (ASC) isolated from the subcutaneous (SAT) and the visceral adipose tissue (VAT). Our results show that, early in obesity and before inflammation was detected, HF diet durably and differently activated ASC from SAT and VAT. Subcutaneous ASC from HF-fed mice strongly inhibited the proliferation of activated T lymphocytes, whereas visceral ASC selectively inhibited TNFα expression by macrophages and simultaneously released higher concentrations of IL6. These depot specific differences may contribute to the low-grade inflammation that develops with obesity in VAT while inflammation in SAT is delayed. The mechanisms involved differ from those already described for naïve cells activation with inflammatory cytokines and probably engaged metabolic activation. These results evidence that adipose stem cells are metabolic sensors acquiring an obesity-primed immunocompetent state in answer to depot-specific intrinsic features with overnutrition, placing these cells ahead of inflammation in the local dialog with immune cells.

Insulin action at a molecular level - 100 years of progress

The discovery of insulin 100 years ago and its application to the treatment of human disease in the years since have marked a major turning point in the history of medicine. The availability of purified insulin allowed for the establishment of its physiological role in the regulation of blood glucose and ketones, the determination of its amino acid sequence, and the solving of its structure. Over the last 50 years, the function of insulin has been applied into the discovery of the insulin receptor and its signaling cascade to reveal the role of impaired insulin signaling-or resistance-in the progression of type 2 diabetes. It has also become clear that insulin signaling can impact not only classical insulin-sensitive tissues, but all tissues of the body, and that in many of these tissues the insulin signaling cascade regulates unexpected physiological functions. Despite these remarkable advances, much remains to be learned about both insulin signaling and how to use this molecular knowledge to advance the treatment of type 2 diabetes and other insulin-resistant states.

Impact of Diabetes Mellitus on the Potential of Autologous Stem Cells and Stem Cell-Derived Microvesicles to Repair the Ischemic Heart

Ischemic heart disease remains the leading cause of morbidity and mortality worldwide. Despite the advances in medical management and catheter-based therapy, mortality remains high, as does the risk of developing heart failure. Regenerative therapies have been widely used as an alternative option to repair the damaged heart mainly because of their paracrine-related beneficial effects. Although cell-based therapy has been demonstrated as feasible and safe, randomized controlled trials and meta-analyses show little consistent benefit from treatments with adult-derived stem cells. Mounting evidence from our group and others supports that cardiovascular risk factors and comorbidities impair stem cell potential thus hampering their autologous use. This review aims to better understand the influence of diabetes on stem cell potential. For this purpose, we will first discuss the most recent advances in the mechanistic understanding of the effects of diabetes on stem cell phenotype, function, and molecular fingerprint to further elaborate on diabetes-induced alterations in stem cell extracellular vesicle profile. Although we acknowledge that multiple sources of stem or progenitor cells are used for regenerative purposes, we will focus on bone marrow hematopoietic stem/progenitor cells, mesenchymal stem cells residing in the bone marrow, and adipose tissue and briefly discuss endothelial colony-forming cells.

Retinol-binding protein 4 in obesity and metabolic dysfunctions

Excessive increased adipose tissue mass in obesity is associated with numerous co-morbid disorders including increased risk of type 2 diabetes, fatty liver disease, hypertension, dyslipidemia, cardiovascular diseases, dementia, airway disease and some cancers. The causal mechanisms explaining these associations are not fully understood. Adipose tissue is an active endocrine organ that secretes many adipokines, cytokines and releases metabolites. These biomolecules referred to as adipocytokines play a significant role in the regulation of whole-body energy homeostasis and metabolism by influencing and altering target tissues function. Understanding the mechanisms of adipocytokine actions represents a hot topic in obesity research. Among several secreted bioactive signalling molecules from adipose tissue and liver, retinol-binding protein 4 (RBP4) has been associated with systemic insulin resistance, dyslipidemia, type 2 diabetes and other metabolic diseases. Here, we aim to review and discuss the current knowledge on RBP4 with a focus on its role in the pathogenesis of obesity comorbid diseases.

Circulating Adiponectin and Resistin Levels Are Associated with Adiposity Indices and Physical Fitness in Healthy Adult Males

BACKGROUND The aim of this study was to assess the correlation of physical fitness scores (PFS) with serum adiponectin, resistin, and adiponectin/resistin ratio (AR ratio) in relation to body adiposity indices in healthy adult males. MATERIAL AND METHODS This cross-sectional study was conducted at the Clinical Physiology Unit, Physiology Department, King Saud University Medical City, King Saud University, Riyadh, from March 2017 to April 2018. We included 125 healthy adult males. Serum samples were obtained after overnight fasting. Analysis was performed for fasting blood glucose (FBG), glycosylated hemoglobin (HbA1c), basal insulin, lipid profile, resistin, and adiponectin. Bioimpedance analysis (BIA) was used to assess body composition. Based on ideal body composition, PFS were computed as previously published for all subjects and compared with serum markers. RESULTS There was a positive correlation of adiponectin with PFS (r=.218, p=0.015) and an inverse correlation with obesity degree (OD), OD (r=-.239, p=0.001), body mass index (BMI) (r=-.244, p=0.001), and waist/hip ratio (WHR) WHR (r=-.296, p=0.001). Moreover, it was correlated negatively with basal insulin (r=-.211, p=0.009) and homeostatic insulin resistance model (HOMA-IR) HOMA-IR (r=-.221, p=0.013). Resistin was correlated negatively with PFS (r=-.203, p=0.023), while its correlation with OD, BMI, WHR, and HOMA-IR was not significant. AR ratio was positively correlated with PFS (r=.286, p=0.001) and negatively with OD (r=-.210, p=0.019), BMI (r=-.222, p=0.013), WHR (r=-.308, p=0.001) and basal insulin (r=-.237, p=0.008). In linear regression analysis, the relationship of PFS was significant with adiponectin (r=.218, p=0.015), resistin (r=-.203, p=0.023) and AR ratio (r=.286, p=0.001). ROC curve analysis showed that individually the values of adiponectin and resistin were not significantly correlated with PFS, but they were significant with the combined AR ratio with AUC 64.6% (p=0.029). CONCLUSIONS Serum adiponectin was positively correlated and resistin was negatively correlated with physical fitness scores based on healthy body composition with low proportion of body adiposity and a higher proportion of fat-free mass. However, the combined effect of adiponectin/resistin ratio is an even better predictor of physical fitness. Moreover, the adiponectin/resistin ratio is even more highly associated with physical fitness than adiponectin or resistin alone.

The autophagy inducer spermidine protects against metabolic dysfunction during overnutrition

Autophagy, a process catabolizing intracellular components to maintain energy homeostasis, impacts aging and metabolism. Spermidine, a natural polyamine and autophagy activator, extends lifespan across a variety of species, including mice. In addition to protecting cardiac and liver tissue, spermidine also affects adipose tissue through unexplored mechanisms. Here, we examined spermidine in the links between autophagy and systemic metabolism. Consistently, daily injection of spermidine delivered even at late life is sufficient to cause a trend in lifespan extension in wild type mice. We further found that spermidine has minimal metabolic effects in young and old mice under normal nutrition. However, spermidine counteracts HFD (high-fat diet)-induced obesity by increasing lipolysis in visceral fat. Mechanistically, spermidine increases the hepatokine FGF21 expression in liver without reducing food intake. Spermidine also modulates FGF21 in adipose tissues, elevating FGF21 expression in subcutaneous fat, but reducing it in visceral fat. Despite this, FGF21 is not required for spermidine action, since Fgf21  -/- mice were still protected from HFD. Furthermore, the enhanced lipolysis by spermidine was also independent of autophagy in adipose tissue, given that adipose-specific autophagy deficient (Beclin-1  flox/+  Fabp4-cre) mice remained spermidine-responsive under HFD. Our results suggest that the metabolic effects of spermidine occurs through systemic changes in metabolism, involving multiple mechanistic pathways.

How the love of muscle can break a heart: Impact of anabolic androgenic steroids on skeletal muscle hypertrophy, metabolic and cardiovascular health

It is estimated 6.4% of males and 1.6% of females globally use anabolic-androgenic steroids (AAS), mostly for appearance and performance enhancing reasons. In combination with resistance exercise, AAS use increases muscle protein synthesis resulting in skeletal muscle hypertrophy and increased performance. Primarily through binding to the androgen receptor, AAS exert their hypertrophic effects via genomic, non-genomic and anti-catabolic mechanisms. However, chronic AAS use also has a detrimental effect on metabolism ultimately increasing the risk of cardiovascular disease (CVD). Much research has focused on AAS effects on blood lipids and lipoproteins, with abnormal concentrations of these associated with insulin resistance, hypertension and increased visceral adipose tissue (VAT). This clustering of interconnected abnormalities is often referred as metabolic syndrome (MetS). Therefore, the aim of this review is to explore the impact of AAS use on mechanisms of muscle hypertrophy and markers of MetS. AAS use markedly decreases high-density lipoprotein cholesterol (HDL-C) and increases low-density lipoprotein cholesterol (LDL-C). Chronic AAS use also appears to cause higher fasting insulin levels and impaired glucose tolerance and possibly higher levels of VAT; however, research is currently lacking on the effects of AAS use on glucose metabolism. While cessation of AAS use can restore normal lipid levels, it may lead to withdrawal symptoms such as depression and hypogonadism that can increase CVD risk. Research is currently lacking on effective treatments for withdrawal symptoms and further long-term research is warranted on the effects of AAS use on metabolic health in males and females.

Significance of Adipose Tissue Maintenance in Patients Undergoing Hemodialysis

In the general population, obesity is known to be associated with adverse outcomes, including mortality. In contrast, high body mass index (BMI) may provide a survival advantage for hemodialysis patients, which is known as the obesity paradox. Although BMI is the most commonly used measure for the assessment of obesity, it does not distinguish between fat and lean mass. Fat mass is considered to serve as an energy reserve against a catabolic condition, while the capacity to survive starvation is also thought to be dependent on its amount. Thus, fat mass is used as a nutritional marker. For example, improvement of nutritional status by nutritional intervention or initiation of hemodialysis is associated with an increase in fat mass. Several studies have shown that higher levels of fat mass were associated with better survival in hemodialysis patients. Based on body distribution, fat mass is classified into subcutaneous and visceral fat. Visceral fat is metabolically more active and associated with metabolic abnormalities and inflammation, and it is thus considered to be a risk factor for cardiovascular disease and mortality. On the other hand, subcutaneous fat has not been consistently linked to adverse phenomena and may reflect nutritional status as a type of energy storage. Visceral and subcutaneous adipose tissues have different metabolic and inflammatory characteristics and may have opposing influences on various outcomes, including mortality. Results showing an association between increased subcutaneous fat and better survival, along with other conditions, such as cancer or cirrhosis, in hemodialysis patients have been reported. This evidence suggests that fat mass distribution (i.e., visceral fat and subcutaneous fat) plays a more important role for these beneficial effects in hemodialysis patients.

Adipocyte-specific deletion of HuR induces spontaneous cardiac hypertrophy and fibrosis

Adipose tissue homeostasis plays a central role in cardiovascular physiology, and the presence of thermogenically active brown adipose tissue (BAT) has recently been associated with cardiometabolic health. We have previously shown that adipose tissue-specific deletion of HuR (Adipo-HuR^-/-) reduces BAT-mediated adaptive thermogenesis, and the goal of this work was to identify the cardiovascular impacts of Adipo-HuR^-/-. We found that Adipo-HuR^-/- mice exhibit a hypercontractile phenotype that is accompanied by increased left ventricle wall thickness and hypertrophic gene expression. Furthermore, hearts from Adipo-HuR^-/- mice display increased fibrosis via picrosirius red staining and periostin expression. To identify underlying mechanisms, we applied both RNA-seq and weighted gene coexpression network analysis (WGCNA) across both cardiac and adipose tissue to define HuR-dependent changes in gene expression as well as significant relationships between adipose tissue gene expression and cardiac fibrosis. RNA-seq results demonstrated a significant increase in proinflammatory gene expression in both cardiac and subcutaneous white adipose tissue (scWAT) from Adipo-HuR^-/- mice that is accompanied by an increase in serum levels of both TNF-α and IL-6. In addition to inflammation-related genes, WGCNA identified a significant enrichment in extracellular vesicle-mediated transport and exosome-associated genes in scWAT, whose expression most significantly associated with the degree of cardiac fibrosis observed in Adipo-HuR^-/- mice, implicating these processes as a likely adipose-to-cardiac paracrine mechanism. These results are significant in that they demonstrate the spontaneous onset of cardiovascular pathology in an adipose tissue-specific gene deletion model and contribute to our understanding of how disruptions in adipose tissue homeostasis may mediate cardiovascular disease.NEW & NOTEWORTHY The presence of functional brown adipose tissue in humans is known to be associated with cardiovascular health. Here, we show that adipocyte-specific deletion of the RNA binding protein HuR, which we have previously shown to reduce BAT-mediated thermogenesis, is sufficient to mediate a spontaneous development of cardiac hypertrophy and fibrosis. These results may have implications on the mechanisms by which BAT function and adipose tissue homeostasis directly mediate cardiovascular disease.

AP2-microRNA-26a overexpression reduces visceral fat mass and blood lipids

BACKGROUND

MicroRNA-26a (miR-26a) is a key player in tumor suppression and plays important roles in glucose and lipid metabolism. However, its function in adipose tissue is not well defined.

OBJECTIVE

The study aimed to examine the effect on fat expansion and function of miR-26a in adipose tissue.

METHODS

Adipose-specific miR-26a transgenic mice (Ap2-miR-26a) were firstly generated by breeding miR-26a floxed (Mir26a^loxP/^loxP) mice with Ap2-Cre recombinase transgenic mice. The effects of miR-26a adipose-specific overexpression on body weight, body fat composition, fat pad weight, adipocyte size, blood lipid levels, glucose metabolism, and adipogenesis were investigated in mice on a chow diet and a high fat diet. White adipose tissue browning was evaluated by energy expenditure, adipocyte morphology and browning related genes expression levels both at room temperature and after cold exposure. Gene expression was determined by Real-Time quantitative PCR and western blotting.

RESULTS

MiR-26a was specifically overexpressed in adipose by ~4 folds. Ap2-miR-26a mice had a moderate decrease in body weight, body fat composition, epididymal white adipose (eWAT) weight and blood lipid levels, along with smaller adipocytes in eWAT. The favorable phenotype was not due to white adipose tissue browning (even after cold exposure) or adipogenesis or lipolysis. Ap2-miR-26a mice exhibited no significant metabolic phenotype under high-fat-diet feeding.

CONCLUSION

This study suggests that adipose-specific overexpression of miR-26a could moderately reduce visceral fat pad mass and lipid levels independent of white adipose tissue browning, adipogenesis and adipose lipolysis based on the gene expression level.

The Impact of H2S on Obesity-Associated Metabolic Disturbances

Over the last several decades, hydrogen sulfide (H₂S) has gained attention as a new signaling molecule, with extensive physiological and pathophysiological roles in human disorders affecting vascular biology, immune functions, cellular survival, metabolism, longevity, development, and stress resistance. Apart from its known functions in oxidative stress and inflammation, new evidence has emerged revealing that H₂S carries out physiological functions by targeting proteins, enzymes, and transcription factors through a post-translational modification known as persulfidation. This review article provides a critical overview of the current state of the literature addressing the role of H₂S in obesity-associated metabolic disturbances, with particular emphasis on its mechanisms of action in obesity, diabetes, non-alcoholic fatty liver disease (NAFLD), and cardiovascular diseases.

Htd2 deficiency-associated suppression of α-lipoic acid production provokes mitochondrial dysfunction and insulin resistance in adipocytes

Mitochondria harbor a unique fatty acid synthesis pathway (mtFAS) with mysterious functions gaining increasing interest, while its involvement in metabolic regulation is essentially unknown. Here we show that 3-Hydroxyacyl-ACP dehydratase (HTD2), a key enzyme in mtFAS pathway was primarily downregulated in adipocytes of mice under metabolic disorders, accompanied by decreased de novo production of lipoic acid, which is the byproduct of mtFAS pathway. Knockdown of Htd2 in 3T3-L1 preadipocytes or differentiated 3T3-L1 mature adipocytes impaired mitochondrial function via suppression of complex I activity, resulting in enhanced oxidative stress and impaired insulin sensitivity, which were all attenuated by supplement of lipoic acid. Moreover, lipidomic study revealed limited lipid alterations in mtFAS deficient cells which primarily presenting accumulation of triglycerides, attributed to mitochondrial dysfunction. Collectively, the present study highlighted the pivotal role of mtFAS pathway in regulating mitochondrial function and adipocytes insulin sensitivity, demonstrating supportive evidence for lipoic acid being potential effective nutrient for improving insulin resistance and related metabolic disorders.

•

3-Hydroxyacyl-ACP dehydratase is decreased in adipocytes under diabetic condition.

•

Deficient of 3-Hydroxyacyl-ACP dehydratase (HTD2) triggers mitochondrial dysfunction.

•

Deficient of HTD2 promotes insulin resistance in adipocytes.

•

Supplement of lipoic acid ameliorates deleterious effects of HTD2 deficiency.

Adipose Tissue Macrophage Polarization in Healthy and Unhealthy Obesity

Over 650 million adults are obese (body mass index ≥ 30 kg/m²) worldwide. Obesity is commonly associated with several comorbidities, including cardiovascular disease and type II diabetes. However, compiled estimates suggest that from 5 to 40% of obese individuals do not experience metabolic or cardiovascular complications. The existence of the metabolically unhealthy obese (MUO) and the metabolically healthy obese (MHO) phenotypes suggests that underlying differences exist in both tissues and overall systemic function. Macrophage accumulation in white adipose tissue (AT) in obesity is typically associated with insulin resistance. However, as plastic cells, macrophages respond to stimuli in their microenvironments, altering their polarization between pro- and anti-inflammatory phenotypes, depending on the state of their surroundings. The dichotomous nature of MHO and MUO clinical phenotypes suggests that differences in white AT function dictate local inflammatory responses by driving changes in macrophage subtypes. As obesity requires extensive AT expansion, we posit that remodeling capacity with adipose expansion potentiates favorable macrophage profiles in MHO as compared with MUO individuals. In this review, we discuss how differences in adipogenesis, AT extracellular matrix deposition and breakdown, and AT angiogenesis perpetuate altered AT macrophage profiles in MUO compared with MHO. We discuss how non-autonomous effects of remote organ systems, including the liver, gastrointestinal tract, and cardiovascular system, interact with white adipose favorably in MHO. Preferential AT macrophage profiles in MHO stem from sustained AT function and improved overall fitness and systemic health.

Clinical Outcomes of Subcutaneous and Visceral Adipose Tissue Characteristics Assessed in Patients Underwent Transcatheter Aortic Valve Replacement

BACKGROUND

Adipose tissue (AT) characteristics are considered to be a marker for predicting clinical outcomes. This study aimed to investigate the prognostic value of subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) computed tomography (CT) assessment in patients who underwent transcatheter aortic valve replacement (TAVR).

METHODS

We used the Japanese multicentre registry data of 1372 patients (age: 84.5 ± 5.0 years, women: 70.6%) who underwent TAVR. The SAT and VAT were assessed according to the preprocedural CT area and density. Baseline characteristics and clinical outcomes were compared based on the differences in AT characteristics. The independent associations with all-cause mortality after TAVR were evaluated according to the CT area and density of AT.

RESULTS

Low-volume area of SAT and VAT was associated with worse clinical outcomes compared with high-volume area of SAT and VAT in patients who underwent TAVR (log-rank test P = 0.016 and P = 0.014). High CT density of SAT and VAT was associated with increasing mortality in comparison with low CT density of SAT and VAT (log-rank test P < 0.001 and P = 0.007). The Cox regression multivariate analysis demonstrated the independent association of increased all-cause mortality in the high SAT and VAT density (hazard ratio [HR]: 1.41, 95% confidence interval [CI]: 1.06-1.88, P = 0.019, and HR: 1.34, 95% CI: 1.03-1.76, P = 0.031, respectively), but not in the low SAT and VAT area (HR: 0.85, 95% CI: 0.74-1.29, P = 0.85, and HR: 0.78, 95% CI: 0.60-1.03, P = 0.085, respectively).

CONCLUSIONS

CT-derived AT characteristics, particularly the qualitative assessments, were useful for predicting the prognosis in patients after TAVR.

Adiposity in Survivors of Cancer in Childhood: How is it Measured and Why Does it Matter?

Survival of cancer in childhood is increasingly common with modern therapeutic protocols but leads frequently to adverse long-term impacts on health, including metabolic and cardiovascular disease. Changes in body composition, especially an increase in fat mass and a decrease in muscle mass, are found early in patients with pediatric cancer, persist long after treatment has been completed and seem to contribute to the development of chronic disease. This review details the effects of such changes in body composition and reviews the underlying pathophysiology of the development of sarcopenic obesity and its adverse metabolic impact. The authors discuss the particular challenges in identifying obesity accurately in survivors of pediatric cancer using available measurement techniques, given that common measures, such as body mass index, do not distinguish between muscle and adipose tissue or assess their distribution. The authors highlight the importance of a harmonized approach to the assessment of body composition in pediatric cancer survivors and early identification of risk using "gold-standard" measurements. This will improve our understanding of the significance of adiposity and sarcopenia in this population, help identify thresholds predictive of metabolic risk, and ultimately prevent or ameliorate the long-term metabolic and cardiovascular impacts on health experienced by survivors of cancer in childhood.