Novel insights into body fat distribution and cardiometabolic risk

Interactome Analysis of Visceral Adipose Tissue Elucidates Gene Regulatory Networks and Novel Gene Candidates in Obesity

Objective

Visceral adiposity is associated with increased proinflammatory activity, insulin resistance, diabetes risk and mortality rate. Numerous individual genes have been associated with obesity, but studies investigating gene-regulatory networks in human visceral obesity are lacking.

Methods

We analyzed gene-regulatory networks in human visceral adipose tissue (VAT) from 48 obese and 11 non-obese Chinese subjects using gene co-expression and network construction with RNA-sequencing data. We also conducted RNA interference-based tests on selected genes for adipocyte differentiation effects.

Results

A scale-free gene co-expression network was constructed from 360 differentially expressed genes between obese and non-obese VAT (absolute log fold-change >1, FDR<0.05) with edge probability >0.8. Gene regulatory network analysis identified candidate transcription factors associated with differentially expressed genes. Fifteen subnetworks (communities) displayed altered connectivity patterns between obese and non-obese networks. Genes in pro-inflammatory pathways showed increased network connectivities in obese VAT whereas the oxidative phosphorylation pathway displayed reduced connections (enrichment FDR<0.05). Functional screening via RNA interference identified SOX30 and OSBPL3 as potential network-derived gene candidates influencing adipocyte differentiation.

Conclusions

This interactome-based approach highlights the network architecture, identifies novel candidate genes, and leads to new hypotheses regarding network-assisted gene regulation in obese vs. non-obese VAT.What is already known about this subject?: Visceral adipose tissue (VAT) is associated with increased levels of proinflammatory activity, insulin resistance, diabetes risk and mortality rate.Gene expression studies have identified candidate genes associated with proinflammatory function in VAT.What are the new findings in your manuscript?: Using integrative network-science, we identified co-expression and gene regulatory networks that are differentially regulated in VAT samples from subjects with and without obesityWe used functional testing (adipocyte differentiation) to validate a subset of novel candidate genes with minimal prior reported associations to obesityHow might your results change the direction of research or the focus of clinical practice: Network biology-based investigation provides a new avenue to our understanding of gene function in visceral adiposityFunctional validation screen allows for the identification of novel gene candidates that may be targeted for the treatment of adipose tissue dysfunction in obesity.

Consumption of Ultraprocessed Foods and Body Fat Distribution Among U.S. Adults

INTRODUCTION

The association between ultraprocessed food consumption and body composition and potential variations by sociodemographic factors is unclear. This study aims to examine the cross-sectional associations of ultraprocessed food consumption with imaging markers of body fat distribution in a nationally representative sample of U.S. adults, overall and by sociodemographic strata.

METHODS

A total of 9,640 men and nonpregnant women aged 20-59 years were included from 4 cycles (2011-2012, 2013-2014, 2015-2016, 2017-2018) of the National Health and Nutrition Examination Survey with valid 24-hour dietary recalls and available whole-body dual-energy x-ray absorptiometry scans. Ultraprocessed foods were identified using the NOVA classification, with percentage energy from ultraprocessed food assessed in quintiles. Primary outcomes were absolute percentage fat (total, android, gynoid), and secondary ones were percentage fat (head, arm, leg, trunk), total abdominal fat (area, mass, volume), subcutaneous adipose tissue (area, mass, volume), and visceral adipose tissue (area, mass, volume). Multivariable-adjusted generalized linear regressions estimated independent relationships of ultraprocessed food intake with body composition overall and by sociodemographic subgroups. Analyses were conducted in September 2022 and January 2023.

RESULTS

Ultraprocessed food consumption accounted for more than half (55.5%) of daily energy consumption in this sample. Adults in the highest quintile (>72.1% energy) had 1.60 higher total percentage fat (95% CI=0.94, 2.26), 2.08 higher android percentage fat (95% CI=1.26, 2.89), and 1.32 higher gynoid percentage fat (95% CI=0.71, 1.93) than those in the lowest quintile of ultraprocessed food consumption (<39.4% energy) (all p-trend<0.001). Consistent findings were observed for secondary outcomes. Associations of ultraprocessed food intake with total percentage fat, android percentage fat, and gynoid percentage fat varied by age, sex, race and ethnicity, education, and income. Among those in the highest quintile of ultraprocessed food consumption compared with the lowest quintile counterpart, total percentage fat was 1.85 (95% CI=0.86, 2.84) higher for non-Hispanic White adults and 1.57 (95% CI=0.68, 2.46) higher for Hispanic adults (p-trends<0.001), whereas no difference was observed among non-Hispanic Black adults (-0.22; 95% CI= -0.93, 1.36) (p-trend=0.47) and non-Hispanic Asian adults (0.93; 95% CI= -0.57, 2.42) (p-trend=0.04) (p-interaction=0.001). Associational patterns were similar for android percentage fat and gynoid percentage fat.

CONCLUSIONS

In a national U.S. sample, higher intake of ultraprocessed food was associated with greater body fat, in particular android fat, and this relationship was most prominent in certain population subgroups. These cross-sectional findings call for prospective and interventional studies to assess the impact of ultraprocessed food on body composition in different populations.

Effect of aerobic exercise and low-carbohydrate high-fat diet on glucose tolerance and android/gynoid fat in overweight/obese women: A randomized controlled trial

The study was designed to compare the effects of weight loss induced by a low-carbohydrate-high-fat diet or a normal diet, with and without exercise, on glucose tolerance measured as area under the curve (AUC), and android (A) and gynoid (G) fat distribution. The study was registered at clinicaltrials.gov; NCT04100356. In total, 57 women classified as overweight or obese (age 40 ± 3.5 years, body mass index 31.1 ± 2.6 kg/m²) were randomly assigned and completed a 10-week intervention using a low-carbohydrate high-fat diet or a normal diet, with or without aerobic interval exercise. An equal deficit of 700 kcal/day was prescribed, either restricting the diet only, or moderately restricting diet and including three 50-min high-intensity bicycle sessions per week. There were thus four groups: normal diet (NORM); low-carbohydrate-high-fat diet (LCHF); normal diet with exercise (NORM-EX); and low-carbohydrate-high-fat diet with exercise (LCHF-EX). Linear mixed models was used to assess differences between groups. With all groups pooled, the intervention resulted in a weight loss of 6.7 ± 2.5% (p < 0.001). The intervention did not result in differences between groups in AUC glucose, nor in fasting glucose or indicis for insulin resistance such as Homeostatic Model Assessment, Matsuda Insulin Sensitivity Index, insulinogenic index and disposition index. Post-intervention android fat was lower in LCHF than NORM (3,223 ± 727 vs. 2,533 ± 535 g, p = 0.041). LCHF reached a lower A/G ratio than NORM (0.94 ± 0.12 vs. 1.04 ± 0.09, p = 0.011) and LCHF-EX (0.94 ± 0.12 vs. 1.09 ± 0.09, p < 0.001) after the intervention. LCHF resulted in lower android fat mass compared to NORM and the lowest A/G ratio compared to the other matched groups, but with no accompanying improvement in AUC glucose. In conclusion, although all groups achieved improvements in glucose tolerance, no superior effect was observed with the LCHF diet, neither with nor without exercise.

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.

High Sensitivity C-reactive Protein (hsCRP) and its Implications in Cardiovascular Outcomes

Atherosclerosis and its fearsome complications represent the first cause of morbidity and mortality worldwide. Over the last two decades, several pieces of evidence have been accumulated, suggesting a central role of inflammation in atheroma development. High sensitivity C-reactive protein (hsCRP) is a well-established marker of cardiovascular (CV) disease; high levels of hsCRP have been associated with adverse CV outcome after acute coronary syndrome (ACS) and, despite some controversy, an active role for hsCRP in initiation and development of the atherosclerotic plaque has been also proposed. Randomized clinical trials focusing on hsCRP have been crucial in elucidating the anti-inflammatory effects of statin therapy. Thus, hsCRP has been progressively considered a real CV risk factor likewise to low-density lipoprotein cholesterol (LDL-C), expanding the concept of residual CV inflammatory risk. Subsequent research has been designed to investigate potential new targets of atherothrombotic protection. Despite the fact that the clinical usefulness of hsCRP is widely recognized, hsCRP may not represent the ideal target of specific anti-inflammatory therapies. Clinical investigations, therefore, have also focused on other inflammatory mediators, restricting hsCRP to an indicator rather than a therapeutic target. The aim of the present review is to provide an illustrative overview of the current knowledge of atherosclerosis and inflammation, highlighting the most representative clinical studies of lipid-lowering and antiinflammatory therapies focused on hsCRP in CV diseases.

Cardiovascular Anthropometry: What Is Best Suited for Large-Scale Population Screening in Sub-Saharan Africa?

Background : Body mass index (BMI) measures overweight/obesity. It, however, especially in sub-Saharan Africa (SSA), misclassifies cardiometabolic risk. Central obesity measures are superior. We therefore sought to compare BMI, waist-to-hip ratio (WHR) and abdominal height (AH) in predicting cardiovascular disease risk in sub-Saharan Africa. Methods : Subjects had blood pressures, BMI, and WHR determined. Blood pressure was taken, weight and height measured to generate BMI, and AH measured with a new locally fabricated abdominometer. The ability of the anthropometric indices in identifying abnormal individuals needing intervention was assessed with sensitivity, specificity, and area under the receiver operator characteristic curve. Results : Adults totaling 1,508 (728 M/780 F) adults were studied. For BMI, 985 (65.3%) were normal, while 375 (24.9%), consisting of 233 males and 142 females, had normal WHR. Blood pressure was normal in 525 (34.8%) and 317 (21.0%) for systolic and diastolic blood pressures, respectively. Using BMI as gold standard, sensitivity, specificity, positive, and negative predictive values for WHR in males were 80.7, 37.5, 62.5, and 19.3%, respectively. For females and in the same order, they were 62.0, 34.3, 65.7, and 38.0%. For AH, it was equal in both genders at 82.6, 39.2, 60.8, and 17.4%. By receiver operating curves comparing AH, WHR, and BMI against blood pressure detection, the area under the curve was 0.745, 0.604, and 0.554 for AH, BMI, and WHR, respectively. Conclusion : Abdominometer-derived AH has a better sensitivity and greater area under the receiver operator curve compared with BMI and WHR in this sub-Sahara African population; implying superiority as a cardiovascular anthropometric index.