Expression of inflammation-related genes in gluteal and abdominal subcutaneous adipose tissue during weight-reducing dietary intervention in obese women

Adipocyte p53 coordinates the response to intermittent fasting by regulating adipose tissue immune cell landscape

In obesity, sustained adipose tissue (AT) inflammation constitutes a cellular memory that limits the effectiveness of weight loss interventions. Yet, the impact of fasting regimens on the regulation of AT immune infiltration is still elusive. Here we show that intermittent fasting (IF) exacerbates the lipid-associated macrophage (LAM) inflammatory phenotype of visceral AT in obese mice. Importantly, this increase in LAM abundance is strongly p53 dependent and partly mediated by p53-driven adipocyte apoptosis. Adipocyte-specific deletion of p53 prevents LAM accumulation during IF, increases the catabolic state of adipocytes, and enhances systemic metabolic flexibility and insulin sensitivity. Finally, in cohorts of obese/diabetic patients, we describe a p53 polymorphism that links to efficacy of a fasting-mimicking diet and that the expression of p53 and TREM2 in AT negatively correlates with maintaining weight loss after bariatric surgery. Overall, our results demonstrate that p53 signalling in adipocytes dictates LAM accumulation in AT under IF and modulates fasting effectiveness in mice and humans.

Distinct inflammatory signatures of upper and lower body adipose tissue and adipocytes in women with normal weight or obesity

Introduction

Upper and lower body fat accumulation poses an opposing obesity-related cardiometabolic disease risk. Depot-differences in subcutaneous adipose tissue (SAT) function may underlie these associations. We aimed to investigate the inflammatory signatures of abdominal (ABD) and femoral (FEM) SAT in postmenopausal women with normal weight or obesity.

Methods

We included 23 postmenopausal women with normal weight (n = 13) or obesity (n = 10). In vivo secretion of adipokines from ABD and FEM SAT was measured using the arterio-venous balance technique. Adipokine gene expression and adipocyte morphology were examined in ABD and FEM SAT. Furthermore, adipokine expression and secretion were investigated in vitro using differentiated human primary ABD and FEM subcutaneous adipocytes derived from the study participants.

Results

Plasma leptin and plasminogen activator inhibitor (PAI)-1 concentrations were higher, and ABD and FEM adipocytes were larger in women with obesity than normal weight. No differences in adipocyte size and blood flow were apparent between ABD and FEM SAT. We found significant release of leptin and monocyte chemoattractant protein (MCP)-1 from ABD and FEM SAT, with higher fractional release of MCP-1 from ABD than FEM SAT. Gene expression of leptin, PAI-1, and tumor necrosis factor-α was lower in ABD than FEM SAT and higher in women with obesity than normal weight. In ABD adipocytes, interleukin-6, PAI-1, and leptin gene expression were higher, while adiponectin and dipeptidyl-peptidase-4 gene expression were lower than in FEM adipocytes. Finally, ABD adipocytes secreted less MCP-1 compared to FEM adipocytes.

Discussion

These findings demonstrate that upper and lower body SAT and adipocytes are characterized by distinct inflammatory signatures in postmenopausal women, which seem independent of adipocyte size.

Body fat distribution and its risk for cardiovascular events in 10 years: Brazilian Longitudinal Study of Adult Health (ELSA-Brasil)

Body fat distribution seems to have different effects in cardiovascular diseases (CVD). We aimed to estimate the associations between lower limbs and trunk fat ratio and the 10-year CVD risk, and isolated risk factors in men and women. A total of 10,917 participants from ELSA-Brasil were eligible for this cross-sectional study. Associations between lower limb/trunk fat ratio with the percentage of 10-year CVD risk - according to the Framingham Risk Score - and its risk factors (systolic blood pressure, total cholesterol and HDL-cholesterol, diabetes, and use of antihypertensive medication) were performed using generalized linear models, linear and logistic regressions. All analyses were stratified by gender and adjustments were made by age, self-reported skin color, educational attainment, alcohol consumption, leisure physical activity, hypolipidemic drug use and, for women, menopausal status. In this study, 55.91% were women, with a mean age of 52.68 (SD = 6.57) years. A higher lower limb/trunk fat ratio was related to lower 10-year CVD risk, as well as a reduction in systolic blood pressure, total cholesterol, and antihypertensive drug use, also an increasing HDL-cholesterol in both genders, but this relationship was stronger in women. Besides, a protective relationship to diabetes was observed in women. Higher fat accumulation in the lower body, when compared to the trunk, seems to have a lower risk of CVD and associated risk factors - even in the presence of fat in the abdominal region - with women presenting lower risks than men.

IL-6 Polymorphisms Are Not Related to Obesity Parameters in Physically Active Young Men

Interleukin 6 (IL-6) is a cytokine with both pro- and anti-inflammatory actions, but is also considered as a "metabolic hormone" involved in immune responses, affecting glucose, protein and lipid metabolism. It has been proposed to be related to obesity, but various results have been presented. Thus, in this study, the very homogenous population of young, male military professionals, living in the same conditions involving high physical activity, has been selected to avoid the influence of environmental factors. The subjects were divided into groups depending on the obesity parameters BMI (body mass index) and fat percentage (fat%), and the following IL-6 SNPs (Single Nucleotide Polymorphisms) were analyzed: rs1800795, rs1800796 and rs13306435. No relation was found between obesity parameters and IL-6 polymorphisms rs1800795, rs1800796 and rs13306435. It may be postulated that even if a genetic predisposition involves IL-6 genes, this effect in individuals with obesity of a low grade is minor, or can be avoided or at least markedly reduced by changes in lifestyle.

Sex Affects Regional Variations in Subcutaneous Adipose Tissue T Cells but not Macrophages in Adults with Obesity

OBJECTIVE

The inflammatory environment in lower-body subcutaneous adipose tissue (SAT) has been largely unexplored. This study aimed to examine the effects of region (upper body vs. lower body) and sex on SAT immune cell profiles in young adults with obesity.

METHODS

Abdominal (AB) and femoral (FEM) SAT was collected from 12 males (mean [SEM] age = 30.8 [1.4] years; mean [SEM] BMI = 34.1 [1.1] kg/m² ) and 22 females (mean [SEM] age = 30.6 [0.6] years; mean [SEM] BMI = 34.0 [0.7] kg/m² ) with obesity via needle aspiration. Flow cytometry was used to quantify macrophage (CD68+) and T-cell (CD3+) subpopulations in the stromovascular fraction of each SAT region.

RESULTS

Females had a greater proportion of most T-cell types (CD3+CD4+CD45RA+, CD3+CD4+CD45RA-, and CD3+CD8+CD45RA+) in FEM compared with AB SAT, while males had similar proportions in both regions. Regardless of sex, the M1-like macrophage population (CD68+CD206-) was proportionally higher in AB SAT than in FEM SAT.

CONCLUSIONS

Results showed that T-cell populations vary by SAT region in females but not males. Both sexes, however, have proportionately more proinflammatory macrophages in upper-body than in lower-body SAT. It remains to be seen how these unique immune cell profiles in males and females with obesity contribute to adipose tissue inflammation and metabolic disease risk.

Neck adipose tissue accumulation is associated with higher overall and central adiposity, a higher cardiometabolic risk, and a pro-inflammatory profile in young adults

OBJECTIVES

Neck adipose tissue (NAT) volume increases with general adiposity, with fat accumulating in different neck tissue compartments. In patients with certain malignant/benign tumours, the accumulation of NAT, and certain NAT distributions, have been associated with cardiometabolic risk (CMR). However, it is unknown whether the same relationships exist in healthy people, and whether NAT accumulation and distribution are related to the inflammatory status.

METHODS

In this cross-sectional study, 139 young healthy adults (68% women) underwent a computed tomography scan to quantify the volume of compartmental (i.e., subcutaneous, intermuscular and perivertebral) and total NAT at the height of vertebra C5. Anthropometric indicators were measured, and body composition determined using dual energy X-ray absorptiometry. Information on CMR factors (i.e., blood glycaemic and lipid markers, blood pressure and physical fitness) was also gathered, and a CMR score calculated. Several plasma cytokines and serum components of the innate immune system were measured to determine the inflammatory status.

RESULTS

Compartmental and total NAT volumes were directly related to body mass index (BMI), and lean, fat, and visceral adipose tissue (VAT) masses (all, P ≤ 0.05). Larger compartmental (especially intermuscular) and total NAT volumes were directly associated with the CMR score, several CMR factors (i.e., glycaemic and lipid markers and blood pressure), and the C3, C4 and leptin concentrations. They were, however, inversely correlated with the CMR factors high density lipoprotein-cholesterol (HDL-C) and physical fitness, and with the adiponectin concentration (all P ≤ 0.05). Several of these associations remained statistically significant (P ≤ 0.05) after adjustment for BMI, body fat percentage or VAT mass. Overall, results did not change after applying false discovery rate correction.

CONCLUSIONS

NAT volume and its distribution among different tissue compartments is associated with the CMR and inflammatory profile of young healthy adults. Total NAT volume appears to be as valuable as VAT mass in terms of predicting CMR and inflammatory status.

The Effect of Habitual Fat Intake, IL6 Polymorphism, and Different Diet Strategies on Inflammation in Postmenopausal Women with Central Obesity

The hypothesis that habitual fat intake, the IL6 genotype, the Mediterranean diet or the central European diet for 16 weeks affect biomarkers of inflammation in centrally obese postmenopausal women, was tested in a randomized controlled trial. Dietary intake was assessed using a three-day food diary. Lipid parameters were measured using a Beckman Coulter AU analyzer. Transcription of TNF and IL6 genes was analyzed in peripheral blood mononuclear cells using real-time PCR. Concentrations of tumor necrosis factor alpha (TNFα) and interleukin 6 (IL6) were measured with ELISA. rs1800795 polymorphism of IL6 was analyzed using hydrolyzing probes. Higher energy intake from fat was associated with higher IL6 levels (p < 0.05). Significantly (p < 0.01) lower total cholesterol (T-C) and low-density lipoprotein cholesterol (LDL-C) concentrations were observed in the GG IL6 rs1800795 genotype group. Both diets significantly (p < 0.001) decreased TNFα concentrations. Neither IL6 gene transcription levels nor blood IL6 concentrations were affected by them. Our findings confirm that habitual fat intake may affect inflammation. The rs1800795 IL6 polymorphism alone did not significantly affect body weight or body composition in aimed group, but C-allele carriers had higher levels of T-C and LDL-C. This polymorphism did not affect inflammation. Both diets may lead to a decrease in TNFα concentration.

Mechanisms of weight regain after weight loss - the role of adipose tissue

One of the biggest challenges in the management of obesity is the prevention of weight regain after successful weight loss. Weight regain after weight loss has large interindividual variation. Although many factors probably contribute to this variation, we hypothesize that variability in biological responses associated with weight loss-induced shrinking of subcutaneous adipocytes has an important role. In this Review, we show that weight loss-induced variations in cellular stress, extracellular matrix remodelling, inflammatory responses, adipokine secretion and lipolysis seem to be associated with the amount of weight that is regained after successful weight loss. Weight regain could therefore, at least in part, depend on a combination of these factors. Further research on the causality of these associations could aid the development of effective strategies to prevent weight regain after successful weight loss.

Effects of dietary supplementation with EPA and/or α-lipoic acid on adipose tissue transcriptomic profile of healthy overweight/obese women following a hypocaloric diet

In obesity, the increment of adiposity levels disrupts the whole body homeostasis, promoting an over production of oxidants and inflammatory mediators. The current study aimed to characterize the transcriptomic changes promoted by supplementation with eicosapentaenoic acid (EPA, 1.3 g/day), α-lipoic acid (0.3 g/day), or both (EPA + α-lipoic acid, 1.3 g/day + 0.3 g/day) in subcutaneous abdominal adipose tissue from overweight/obese healthy women, who followed a hypocaloric diet (30% of total energy expenditure) during ten weeks, by using a microarray approach. At the end of the intervention, a total of 33,297 genes were analyzed using Affymetrix GeneChip arrays. EPA promoted changes in extracellular matrix remodeling gene expression, besides a rise of genes associated with either chemotaxis or wound repair. α-Lipoic acid decreased expression of genes related with cell adhesion and inflammation. Furthermore, α-lipoic acid, especially in combination with EPA, upregulated the expression of genes associated with lipid catabolism while downregulated genes involved in lipids storage. Together, all these data suggest that some of the metabolic effects of EPA and α-lipoic acid could be related to their regulatory actions on adipose tissue metabolism. © 2016 BioFactors, 43(1):117-131, 2017.

The Metabolic Phenotype in Obesity: Fat Mass, Body Fat Distribution, and Adipose Tissue Function

The current obesity epidemic poses a major public health issue since obesity predisposes towards several chronic diseases. BMI and total adiposity are positively correlated with cardiometabolic disease risk at the population level. However, body fat distribution and an impaired adipose tissue function, rather than total fat mass, better predict insulin resistance and related complications at the individual level. Adipose tissue dysfunction is determined by an impaired adipose tissue expandability, adipocyte hypertrophy, altered lipid metabolism, and local inflammation. Recent human studies suggest that adipose tissue oxygenation may be a key factor herein. A subgroup of obese individuals - the 'metabolically healthy obese' (MHO) - have a better adipose tissue function, less ectopic fat storage, and are more insulin sensitive than obese metabolically unhealthy persons, emphasizing the central role of adipose tissue function in metabolic health. However, controversy has surrounded the idea that metabolically healthy obesity may be considered really healthy since MHO individuals are at increased (cardio)metabolic disease risk and may have a lower quality of life than normal weight subjects due to other comorbidities. Detailed metabolic phenotyping of obese persons will be invaluable in understanding the pathophysiology of metabolic disturbances, and is needed to identify high-risk individuals or subgroups, thereby paving the way for optimization of prevention and treatment strategies to combat cardiometabolic diseases.

Effects of Moderate and Subsequent Progressive Weight Loss on Metabolic Function and Adipose Tissue Biology in Humans with Obesity

Although 5%-10% weight loss is routinely recommended for people with obesity, the precise effects of 5% and further weight loss on metabolic health are unclear. We conducted a randomized controlled trial that evaluated the effects of 5.1% ± 0.9% (n = 19), 10.8% ± 1.3% (n = 9), and 16.4% ± 2.1% (n = 9) weight loss and weight maintenance (n = 14) on metabolic outcomes. 5% weight loss improved adipose tissue, liver and muscle insulin sensitivity, and β cell function, without a concomitant change in systemic or subcutaneous adipose tissue markers of inflammation. Additional weight loss further improved β cell function and insulin sensitivity in muscle and caused stepwise changes in adipose tissue mass, intrahepatic triglyceride content, and adipose tissue expression of genes involved in cholesterol flux, lipid synthesis, extracellular matrix remodeling, and oxidative stress. These results demonstrate that moderate 5% weight loss improves metabolic function in multiple organs simultaneously, and progressive weight loss causes dose-dependent alterations in key adipose tissue biological pathways.

Biology of upper-body and lower-body adipose tissue--link to whole-body phenotypes

The distribution of adipose tissue in the body has wide-ranging and reproducible associations with health and disease. Accumulation of adipose tissue in the upper body (abdominal obesity) is associated with the development of cardiovascular disease, insulin resistance, type 2 diabetes mellitus and even all-cause mortality. Conversely, accumulation of fat in the lower body (gluteofemoral obesity) shows opposite associations with cardiovascular disease and type 2 diabetes mellitus when adjusted for overall fat mass. The abdominal depots are characterized by rapid uptake of predominantly diet-derived fat and a high lipid turnover that is easily stimulated by adrenergic receptor activation. The lower-body fat stores have a reduced lipid turnover with a capacity to accommodate fat undergoing redistribution. Lower-body adipose tissue also seems to retain the capacity to recruit additional adipocytes as a result of weight gain and demonstrates fewer signs of inflammatory insult. New data suggest that the profound functional differences between the upper-body and lower-body tissues are controlled by site-specific sets of developmental genes, such as HOXA6, HOXA5, HOXA3, IRX2 and TBX5 in subcutaneous abdominal adipose tissue and HOTAIR, SHOX2 and HOXC11 in gluteofemoral adipose tissue, which are under epigenetic control. This Review discusses the developmental and functional differences between upper-body and lower-body fat depots and provides mechanistic insight into the disease-protective effects of lower-body fat.

Regional adipose tissue hormone/cytokine production before and after weight loss in abdominally obese women

OBJECTIVE

To compare the regional differences in subcutaneous adipose tissue hormone/cytokine production in abdominally obese women during weight loss.

METHODS

Forty-two abdominally obese, older women underwent a 20-week weight loss intervention composed of hypocaloric diet with or without aerobic exercise (total energy expenditure: ∼2800 kcal/week). Subcutaneous (gluteal and abdominal) adipose tissue biopsies were conducted before and after the intervention. Adipose tissue gene expression and release of leptin, adiponectin, and interleukin 6 (IL-6) were determined.

RESULTS

The intervention resulted in significant weight loss (-10.1 ± 0.7 kg, P < 0.001). At baseline, gene expression of adiponectin were higher (P < 0.01), and gene expression and release of IL-6 were lower (both P < 0.05) in abdominal than in gluteal adipose tissue. After intervention, leptin gene expression and release were lower in both gluteal and abdominal adipose tissue compared to baseline (P < 0.05-0.01). Abdominal, but not gluteal, adipose tissue adiponectin gene expression and release increased after intervention (both P < 0.05).

CONCLUSION

A 20-week weight loss program decreased leptin production in both gluteal and abdominal adipose tissue, but only increased adiponectin production from abdominal adipose tissue in obese women. This depot-specific effect may be of importance for the treatment of health complications associated with abdominal adiposity.