Body mass index is associated with region-dependent metabolic reprogramming of adipose tissue

Lipodystrophy as a target to delay premature aging

Lipodystrophy syndromes are rare diseases characterized by low levels and an abnormal distribution of adipose tissue, caused by diverse genetic or acquired causes. These conditions commonly exhibit metabolic complications, including insulin resistance, diabetes, hypertriglyceridemia, nonalcoholic fatty liver disease, and adipose tissue dysfunction. Moreover, genetic lipodystrophic laminopathies exhibit a premature aging phenotype, emphasizing the importance of restoring adipose tissue distribution and function. In this opinion, we discuss the relevance of adipose tissue reestablishment as a potential approach to alleviate premature aging and age-related complications in genetic lipodystrophy syndromes.

Dysglycemia Shapes Visceral Adipose Tissue's Response to GIP, GLP-1 and Glucagon in Individuals with Obesity

Visceral adipose tissue (VAT) metabolic fingerprints differ according to body mass index (BMI) and glycemic status. Glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and glucagon are gut-associated hormones that play an important role in regulating energy and glucose homeostasis, although their metabolic actions in VAT are still poorly characterized. Our aim was to assess whether GLP-1, GIP and glucagon influence the VAT metabolite profile. To achieve this goal, VAT harvested during elective surgical procedures from individuals (N = 19) with different BMIs and glycemic statuses was stimulated with GLP-1, GIP or glucagon, and culture media was analyzed using proton nuclear magnetic resonance. In the VAT of individuals with obesity and prediabetes, GLP-1 shifted its metabolic profile by increasing alanine and lactate production while also decreasing isoleucine consumption, whereas GIP and glucagon decreased lactate and alanine production and increased pyruvate consumption. In summary, GLP-1, GIP and glucagon were shown to distinctively modulate the VAT metabolic profile depending on the subject's BMI and glycemic status. In VAT from patients with obesity and prediabetes, these hormones induced metabolic shifts toward gluconeogenesis suppression and oxidative phosphorylation enhancement, suggesting an overall improvement in AT mitochondrial function.

Abdominal Adipose Tissue Associates With Adiponectin and TNFα in Middle-Aged Healthy Men

INTRODUCTION

Adipokines are highly active biopeptides involved in glucose metabolism, insulin regulation and the development and progression of obesity and its associated diseases. It includes, among others, adiponectin, visfatin and tumor necrosis factor alpha (TNFα). The sources of adipokines and their associations with glucometabolic variables are not completely understood.

AIM

In this cross-sectional study, we aimed to investigate whether gene expression levels in subcutaneous adipose tissue (SAT) of selected adipokines and their corresponding circulating levels associate with the amount of AT in superficial (sSAT), deep (dSAT) and visceral AT (VAT), assessed by computed tomography (CT). Any association with glucometabolic variables were also explored.

METHODS

In 103 healthy Caucasian men, aged 39.5 years, fasting venous blood and SAT samples from the gluteal region were collected. Ninety-four of the participants underwent CT assessment of the abdominal AT, which was divided into VAT, sSAT and dSAT. Circulating levels of adipokines were measured by ELISA and AT gene-expression by PCR. Insulin sensitivity was determined by glucose clamp, assessing glucose disposal rate (GDR).

RESULTS

Circulating adiponectin and TNFα gene expression correlated inversely and positively to the amount of AT in all three compartments (r=-0.266 to -0.276, p<0.05 for all) and (r=0.323 - 0.368, p<0.05 for all), respectively, with strongest correlations to the amount in sSAT and dSAT. When dividing AT compartments into quartiles, a tendency was observed towards lower circulating adiponectin and higher TNFα gene expression levels, respectively, with increasing amount of sSAT and dSAT. Circulating adiponectin correlated inversely to insulin, C-peptide and waist circumference (r=-456 to -0.373, p<0.001) and positively to GDR (r=0.356, p<0.001). AT-expressed visfatin correlated inversely to insulin and C-peptide (r=-0.370 and r=-0.404, p<0.001).

CONCLUSION

Increased amount of AT is associated with lower levels of adiponectin and increased levels of TNFα AT expression.

Visceral Adipose Tissue Displays Unique Metabolomic Fingerprints in Obesity, Pre-Diabetes and Type 2 Diabetes

Visceral adipose tissue (VAT) metabolic profiling harbors the potential to disentangle molecular changes underlying obesity-related dysglycemia. In this study, the VAT exometabolome of subjects with obesity and different glycemic statuses are analyzed. The subjects (n = 19) are divided into groups according to body mass index and glycemic status: subjects with obesity and euglycemia (Ob+NGT, n = 5), subjects with obesity and pre-diabetes (Ob+Pre-T2D, n = 5), subjects with obesity and type 2 diabetes under metformin treatment (Ob+T2D, n = 5) and subjects without obesity and with euglycemia (Non-Ob, n = 4), used as controls. VATs are incubated in culture media and extracellular metabolite content is determined by proton nuclear magnetic resonance (1H-NMR). Glucose consumption is not different between the groups. Pyruvate and pyroglutamate consumption are significantly lower in all groups of subjects with obesity compared to Non-Ob, and significantly lower in Ob+Pre-T2D as compared to Ob+NGT. In contrast, isoleucine consumption is significantly higher in all groups of subjects with obesity, particularly in Ob+Pre-T2D, compared to Non-Ob. Acetate production is also significantly lower in Ob+Pre-T2D compared to Non-Ob. In sum, the VAT metabolic fingerprint is associated with pre-diabetes and characterized by higher isoleucine consumption, accompanied by lower acetate production and pyruvate and pyroglutamate consumption. We propose that glucose metabolism follows different fates within the VAT, depending on the individuals' health status.

Anthropometric measurements of school-going-girls of the Punjab, Pakistan

BACKGROUND

Child's growth has been considered an important indicator to evaluate health trends in a population and to devise strategies accordingly. The purpose of the present study was to determine most commonly occurring weight abnormalities among school-going girls from Punjab and to compare with international growth references devised by World Health Organization (WHO) and Centre for Disease Control and Prevention (CDC).

METHODS

In this cross-sectional study a sample of 10,050 child and adolescent girls from 12 districts, 35 public/private sector schools, located in rural, semi-urban and urban areas of northern, central and southern Punjab were included. Parameters were measured according to standardised techniques and centile curves obtained by Lambda, Mu, Sigma (LMS) method.

RESULTS

The results showed an increase in weight, height and BMI of the Punjabi girls until 15 years. When compared with international growth references, weight and BMI in our population were significantly lowered; however, height was lower during 12-16 years of age and the differences observed were more pronounced with CDC as compared to WHO. When 3rd, 50th and 90th percentiles of weight, height and BMI in our population were compared with international standards, the values were lower in our paediatric population.

CONCLUSION

The Punjabi schoolgirls significantly differed from CDC and WHO references, and this difference should be taken into consideration for evaluation of growth abnormalities in our paediatric population. However, in the absence of national reference data, WHO standards have been considered more appropriate for comparison.

Changes in plasma phospholipid fatty acid profiles over 13 years and correlates of change: European Prospective Investigation into Cancer and Nutrition-Norfolk Study

BACKGROUND

Little is known about changes in blood fatty acid compositions over time and the correlates of any changes in a general population.

OBJECTIVE

The aim of this study was to estimate changes in 27 individual plasma phospholipid fatty acids and fatty acid groups over time, and to identify potential correlates of these changes.

METHODS

Plasma phospholipid fatty acids were profiled at 3 time-points (1993-1997, 1998-2000, 2004-2011) among 722 participants in the European Prospective Investigation into Cancer and Nutrition-Norfolk Study, UK. Linear regression models were used to estimate both 1) mean changes over time in 27 individual fatty acids and 8 prespecified fatty acid groups and 2) associations of changes in dietary and lifestyle factors with changes in the 8 fatty acid groups, mutually adjusted for dietary/lifestyle factors and other confounders. The prespecified fatty acid groups were odd-chain saturated fatty acids (SFAs), even-chain SFAs, very-long-chain SFAs, marine n-3 polyunsaturated fatty acids (PUFAs), plant n-3 PUFA, n-6 PUFAs, monounsaturated fatty acids (MUFAs), and trans-fatty acids (TFAs).

RESULTS

Adjusted for confounders, fatty acid concentrations decreased for odd-chain SFAs (annual percentage difference in mol percentage: -0.63%), even-chain SFAs (-0.05%), n-6 PUFAs (-0.25%), and TFAs (-7.84%). In contrast, concentrations increased for marine n-3 PUFAs (1.28%) and MUFAs (0.45%), but there were no changes in very-long-chain SFAs or plant n-3 PUFA. Changes in fatty acid levels were associated with consumption of different food groups. For example, a mean 100 g/d increase in fatty fish intake was associated with a 19.3% greater annual increase in marine n-3 PUFAs.

CONCLUSIONS

Even-chain SFAs and TFAs declined and marine n-3 PUFAs increased over time. These changes were partially explained by changes in dietary habits, and could potentially help interpret associations of baseline fatty acid composition with future disease risk.

Transcriptome Profiles of Human Visceral Adipocytes in Obesity and Colorectal Cancer Unravel the Effects of Body Mass Index and Polyunsaturated Fatty Acids on Genes and Biological Processes Related to Tumorigenesis

Obesity, a low-grade inflammatory condition, represents a major risk factor for the development of several pathologies including colorectal cancer (CRC). Although the adipose tissue inflammatory state is now recognized as a key player in obesity-associated morbidities, the underlying biological processes are complex and not yet precisely defined. To this end, we analyzed transcriptome profiles of human visceral adipocytes from lean and obese subjects affected or not by CRC by RNA sequencing (n = 6 subjects/category), and validated selected modulated genes by real-time qPCR. We report that obesity and CRC, conditions characterized by the common denominator of inflammation, promote changes in the transcriptional program of adipocytes mostly involving pathways and biological processes linked to extracellular matrix remodeling, and metabolism of pyruvate, lipids and glucose. Interestingly, although the transcriptome of adipocytes shows several alterations that are common to both disorders, some modifications are unique under obesity (e.g., pathways associated with inflammation) and CRC (e.g., TGFβ signaling and extracellular matrix remodeling) and are influenced by the body mass index (e.g., processes related to cell adhesion, angiogenesis, as well as metabolism). Indeed, cancer-induced transcriptional program is deeply affected by obesity, with adipocytes from obese individuals exhibiting a more complex response to the tumor. We also report that in vitro exposure of adipocytes to ω3 and ω6 polyunsaturated fatty acids (PUFA) endowed with either anti- or pro-inflammatory properties, respectively, modulates the expression of genes involved in processes potentially relevant to carcinogenesis, as assessed by real-time qPCR. All together our results suggest that genes involved in pyruvate, glucose and lipid metabolism, fibrosis and inflammation are central in the transcriptional reprogramming of adipocytes occurring in obese and CRC-affected individuals, as well as in their response to PUFA exposure. Moreover, our results indicate that the transcriptional program of adipocytes is strongly influenced by the BMI status in CRC subjects. The dysregulation of these interrelated processes relevant for adipocyte functions may contribute to create more favorable conditions to tumor establishment or favor tumor progression, thus linking obesity and colorectal cancer.

MRI assessment of changes in adipose tissue parameters after bariatric surgery

Bariatric surgery and other therapeutic options for obese patients are often evaluated by the loss of weight, reduction of comorbidities or improved quality of life. However, little is currently known about potential therapy-related changes in the adipose tissue of obese patients. The aim of this study was therefore to quantify fat fraction (FF) and T1 relaxation time by magnetic resonance imaging (MRI) after Roux-en-Y gastric bypass surgery and compare the resulting values with the preoperative ones. Corresponding MRI data were available from 23 patients (16 females and 7 males) that had undergone MRI before (M0) and one month after (M1) bariatric surgery. Patients were 22–59 years old (mean age 44.3 years) and their BMI ranged from 35.7–54.6 kg/m² (mean BMI 44.6 kg/m²) at M0. Total visceral AT volumes (V_VAT-T, in L) were measured by semi-automatic segmentation of axial MRI images acquired between diaphragm and femoral heads. MRI FF and T1 relaxation times were measured in well-defined regions of visceral (VAT) and subcutaneous (SAT) adipose tissue using two custom-made analysis tools. Average BMI values were 45.4 kg/m² at time point M0 and 42.4 kg/m² at M1. Corresponding V_VAT-T values were 5.94 L and 5.33 L. Intraindividual differences in both BMI and V_VAT-T were highly significant (p<0.001). Average relaxation times T1_VAT were 303.7 ms at M0 and 316.9 ms at M1 (p<0.001). Corresponding T1_SAT times were 283.2 ms and 280.7 ms (p = 0.137). Similarly, FF_VAT differences (M0: 85.7%, M1: 83.4%) were significant (p <0.01) whereas FF_SAT differences (M0: 86.1, M1: 85.9%) were not significant (p = 0.517). In conclusion, bariatric surgery is apparently not only related to a significant reduction in common parameters of adipose tissue distribution, here BMI and total visceral fat volume, but also significant changes in T1 relaxation time and fat fraction of visceral adipose tissue. Such quantitative MRI measures may potentially serve as independent biomarkers for longitudinal and cross-sectional measurements in obese patients.