Role of subcutaneous adipose tissue in metabolic complications of obesity

Butyrate prevents visceral adipose tissue inflammation and metabolic alterations in a Friedreich's ataxia mouse model

Friedreich's ataxia (FA) is a neurodegenerative disease resulting from a mutation in the FXN gene, leading to mitochondrial frataxin deficiency. FA patients exhibit increased visceral adiposity, inflammation, and heightened diabetes risk, negatively affecting prognosis. We investigated visceral white adipose tissue (vWAT) in a murine model (KIKO) to understand its role in FA-related metabolic complications. RNA-seq analysis revealed altered expression of inflammation, angiogenesis, and fibrosis genes. Diabetes-like traits, including larger adipocytes, immune cell infiltration, and increased lactate production, were observed in vWAT. FXN downregulation in cultured adipocytes mirrored vWAT diabetes-like features, showing metabolic shifts toward glycolysis and lactate production. Metagenomic analysis indicated a reduction in fecal butyrate-producing bacteria, known to exert antidiabetic effects. A butyrate-enriched diet restrained vWAT abnormalities and mitigated diabetes features in KIKO mice. Our work emphasizes the role of vWAT in FA-related metabolic issues and suggests butyrate as a safe and promising adjunct for FA management.

Nutrition Meets Social Marketing: Targeting Health Promotion Campaigns to Young Adults Using the Living and Eating for Health Segments

Young adults are a key target age group for lifestyle behaviour change as adoption of healthier behaviours has the potential to impact long term health. This paper arises from a multi-disciplinary research project, Communicating Health, which aims to bridge the gap between nutritionists, media, and social marketing professionals to produce the tools that may be used to improve engagement with young adults and reduce the prevalence of obesity. The aim of this paper is to provide nuanced details of the psycho-behavioral characteristics of each of these Living and Eating for Health Segments (LEHS). The design and validation of the LEHS employed a four-stage mixed methods design underpinned by the Integrated Model of Behaviour Change and incorporating sequential formative, qualitative, and quantitative phases. This paper defines the psycho-behavioural characteristics of six distinct market segments: Lifestyle Mavens, Aspirational Healthy Eaters, Balanced-all Rounders, the Health Conscious, those Contemplating Another Day, and the Blissfully Unconcerned. These psycho-behavioural characteristics are important to understand to help build our capability in designing campaigns that are specifically and purposefully targeting these different market segments of young adults. Social marketing practices can enhance the utility of nutrition and health messages to young adults in order to engage them in adopting positive lifestyle change. Tailoring health promotions to the perceived needs of sub-groups or segments of young adults should lead to increased engagement and uptake of messages and cost-efficient use of health promotion budgets.

The role of vitamin D in adipogenesis

Vitamin D, a secosteroid predominately obtained by endogenous production, has in recent years been linked to obesity and its comorbidities. The purpose of this review is to draw conclusions from animal and human studies on the effects of vitamin D on adipogenesis to identify the molecular links between vitamin D and obesity. The information presented herein was obtained from 4 databases (PubMed, CINAHL, Cochrane Library, Scopus) using predefined search terms, as well as research literature and other reviews. The effects of vitamin D on adipogenesis have been researched in several animal models, and the majority of these studies suggest vitamin D plays an inhibitory role in adipogenesis. Studies into vitamin D status and obesity in humans are limited, with the majority being observational epidemiological studies that provide no conclusions on cause and effect or clear links on the molecular mechanisms. The few cell culture and supplementation studies that have investigated adipogenesis in human cells indicate that, in contrast to findings from rodent studies, vitamin D is proadipogenic. There is insufficient evidence to determine whether 1) vitamin D deficiency is associated with a lean or obese phenotype, 2) vitamin D deficiency is a consequence of obesity, or (3) the effects of vitamin D on fat tissue are due to interactions with calcium.

Association of Habitual Patterns and Types of Physical Activity and Inactivity with MRI-Determined Total Volumes of Visceral and Subcutaneous Abdominal Adipose Tissue in a General White Population

Population-based evidence for the role of habitual physical activity (PA) in the accumulation of visceral (VAT) and subcutaneous (SAAT) abdominal adipose tissue is limited. We investigated if usual patterns and types of self-reported PA and inactivity were associated with VAT and SAAT in a general white population. Total volumes of VAT and SAAT were quantified by magnetic resonance imaging in 583 men and women (61 ± 11.9 y; BMI 27.2 ± 4.4 kg/m2). Past-year PA and inactivity were self-reported by questionnaire. Exploratory activity patterns (APAT) were derived by principal components analysis. Cross-sectional associations between individual activities, total PA in terms of metabolic equivalents (PA MET), or overall APAT and either VAT or SAAT were analyzed by multivariable-adjusted robust or generalized linear regression models. Whereas vigorous-intensity PA (VPA) was negatively associated with both VAT and SAAT, associations between total PA MET, moderate-intensity PA (MPA), or inactivity and VAT and/or SAAT depended on sex. There was also evidence of a threshold effect in some of these relationships. Total PA MET was more strongly associated with VAT in men (B = -3.3 ± 1.4; P = 0.02) than women (B = -2.1 ± 1.1; P = 0.07), but was more strongly associated with SAAT in women (B = -5.7 ± 2.5; P = 0.05) than men (B = -1.7 ± 1.6; P = 0.3). Men (-1.52 dm3 or -1.89 dm3) and women (-1.15 dm3 or -2.61 dm3) in the highest (>6.8 h/wk VPA) or second (4.0-6.8 h/wk VPA) tertile of an APAT rich in VPA, had lower VAT and SAAT, respectively, than those in the lowest (<4.0 h/wk VPA) tertile (P ≤ 0.016; P trend ≤ 0.0005). They also had lower VAT and SAAT than those with APAT rich in MPA and/or inactivity only. In conclusion, our results suggest that in white populations, habitual APAT rich in MPA might be insufficient to impact on accumulation of VAT or SAAT. APAT including ≥ 4.0-6.8 h/wk VPA, by contrast, are more strongly associated with lower VAT and SAAT.

MRI-determined total volumes of visceral and subcutaneous abdominal and trunk adipose tissue are differentially and sex-dependently associated with patterns of estimated usual nutrient intake in a northern German population

BACKGROUND

Visceral (VAT) and subcutaneous abdominal (SAAT) and trunk (STRAT) adipose tissue (AT) have been suggested to be differentially influenced by diet.

OBJECTIVE

We investigated whether and to what extent usual patterns of nutrient intake are associated with VAT, SAAT, and STRAT compared with nondietary predictors in northern German adults (n = 583).

DESIGN

AT volumes were quantified by magnetic resonance imaging. Nutrient intake was estimated by a 112-item food-frequency questionnaire linked to the German Food Code and Nutrient Database. Exploratory nutrient patterns were derived by principal components analysis (PCA) and partial least-squares regression (PLS) of 87 nutrients. Cross-sectional associations between nutrient patterns, single nutrients, or total energy intake and AT compartments were analyzed by multiple linear regression.

RESULTS

Next to sex and age, respectively, which were important nondietary predictors and accounted for more of the variation in VAT (∼13% and ∼4%) than in SAAT or STRAT (both 4-7% and <1%), variation in VAT (16.8% or 17.6%) was explained to a greater extent by 9 or 2 nutrient patterns derived by principal components analysis or partial least-squares regression, respectively, than was variation in SAAT (10.6% or 8.2%) or STRAT (11.5% or 8.6%). Whereas VAT (16.6%) was primarily explained by nutrient quality, SAAT (6.9%) and STRAT (7.4%) were mainly explained by total energy intake. VAT was positively associated with nutrients characteristic of animal (except for dairy) products, including arachidonic acid (standardized β: 0.25; 95% CI: 0.15, 0.34; P < 0.0001), but negatively with dietary fiber, including polypentoses (standardized β: -0.17; 95% CI: -0.24, -0.09; P < 0.0001), and nutrients found in milk. The direction and strength of many associations, however, depended strongly on sex and adjustment for BMI.

CONCLUSION

VAT may be particularly associated with sex-specific interplays of nutrients found in animal products and fiber, whereas SAAT and STRAT are associated with total energy intake.

Continued loss in visceral and intermuscular adipose tissue in weight-stable women following bariatric surgery

OBJECTIVE

To assess changes in total (TAT), subcutaneous (SAT), visceral (VAT), and intermuscular (IMAT) adipose tissue by whole-body MRI before surgery and at 12 months and 24 months post-surgery in a subset of participants of the Longitudinal Assessment of Bariatric Surgery-2.

METHODS

From 0 to 12 months, n = 20 females and 3 males; from 12 to 24 months, n = 42 females and 7 males. Paired t-tests and GLM repeated measures examined changes in TAT, SAT, VAT, and IMAT at 12 and 24 months, with sex and age as covariates.

RESULTS

Changes from 0 to 12 months included weight (-41.9 ± 12.1 kg; -36%), TAT (-33.5 ± 9.6 kg; -56%), SAT (-29.2 ± 8.2 kg; -55%), VAT (-3.3 ± 1.6 kg; -73%), and IMAT (-0.99 ± 0.68 kg; -50%), all P < 0.001. In females, from 12 to 24 months, despite relative weight stability (-1.8 ± 6.5 kg, -2%; P = 0.085), VAT (-0.5 ± 0.7 kg; -30%; P < 0.001) and IMAT (-0.2 ± 0.4 kg; -14%; P = 0.012) decreased further. In males, from 12 to 24 months, weight increased (5.1 ± 5.2 kg; 6%; P = 0.04) with no significant changes in TAT or sub-depots.

CONCLUSIONS

Bariatric surgery continues to induce favorable changes in body composition, i.e., persistent adipose tissue loss at 24 months in the absence of further significant weight loss.

Metabolic basis of ethnic differences in diabetes risk in overweight and obese youth

The global pandemic of childhood obesity has led to increased risk for prediabetes and type 2 diabetes mellitus (T2DM). Studies have shown decreased insulin sensitivity and/or secretion with increasing adiposity and consistently observed greater risk for T2DM in obese, non-Caucasian youth. In the current review we describe recent advances in understanding how obesity and metabolic status in children and adolescents confers various risk profiles for T2DM among Latinos, African Americans, Caucasians, Asians, and Native Americans. These possible determinants include ectopic fat distribution, adipose tissue inflammation and fibrosis, and elevated plasma levels of nonesterified free fatty acids. Future work should aim to elucidate the ethnic-specific pathophysiology of T2DM in order to develop and implement appropriate prevention and treatment strategies based on different ethnic profiles of diabetes risk.

Heterogeneity in subcutaneous adipose tissue morphology and metabolic complications in overweight and obese women

OBJECTIVE

The aim of this study was to assess morphological features of intact adipose tissue (AT) ex vivo from both subcutaneous (s.c.) abdominal and gluteal areas using a novel approach of multiphoton autofluorescence microscopy (MPAM) combined with second harmonic generation microscopy (SHGM), and to assess the relationship between morphological features in the two AT sites and insulin resistance to peripheral glucose disposal.

METHOD

This study was a cross-sectional evaluation of AT morphology feature and peripheral insulin resistance.

SUBJECTS

Fourteen overweight/obese premenopausal women underwent body composition studies, hyperinsulinemic-euglycemic clamps, and needle biopsy of both the s.c. abdominal and gluteal AT areas. MPAM combined with SHGM was used to measure adipocyte maximal diameter and collagen fiber bundle thickness within a sampled image volume after three-dimensional visualization.

RESULTS

Higher body mass index (BMI) was associated with larger adipocyte diameter in s.c. abdominal, but not gluteal, AT. Higher adipocyte diameter was associated with higher pericellular collagen thickness. Adipocyte diameter in s.c. abdominal, but not gluteal, AT was associated positively with leptin and negatively with adiponectin plasma levels and peripheral glucose disposal rate. The latter correlation was no longer significant after adjustment for collagen thickness.

CONCLUSION

In overweight/obese premenopausal women, larger adipocyte diameter in s.c. abdominal, but not gluteal, AT associates with low plasma adiponectin and systemic insulin resistance, and suggests that increased collagen thickness (obesity-related scarring) could contribute to these findings.

UP780, a chromone-enriched aloe composition improves insulin sensitivity

BACKGROUND

Diabetic individuals experience elevated fasting glucose, glycosylated hemoglobin (HbA1c), and plasma insulin and impaired glucose tolerance. Adiponectin is a hormone inversely correlated with insulin resistance. Here we describe the activity of aloesin, an aloe chromone that increases adiponectin production and, when formulated with an aloe polysaccharide composition, improves the insulin sensitivity in db/db and diet-induced obese-diabetic mice.

METHODS

Two aloe chromones, aloesin and aloesinol, were tested in vitro for adiponectin production. Following confirmation of glucose-lowering activity in a high-fat diet (HFD)-induced mouse model, aloesin was formulated with an Aloe vera inner leaf gel powder polysaccharide preparation to yield a composition designated UP780. Efficacy of UP780 was evaluated in HDF-induced and db/db mouse models. GW1929, a synthetic peroxisome proliferator-activated receptor-γ (PPARγ) agonist, was used as a positive control.

RESULTS

After 3 weeks of treatment of HDF-induced mice, plasma insulin levels were decreased 37.9% and 46.7% by aloesin and aloesinol, respectively. In db/db mice, the chromone- (2% chromone:98% aloe polysaccharide) enriched UP780 aloe composition showed a 33.7% and 46.0% decrease in fasting triglyceride and plasma glucose levels after 10 weeks of oral treatment, respectively. Diabetic mice gavaged with 200 mg/kg of UP780 for 10 weeks showed a 30.3% decrease in fasting blood glucose levels and a 32.2% reduction in plasma insulin. In both animal models, UP780 showed a statistically significant improvement in blood glucose clearance.

CONCLUSION

These findings indicate that UP780, a chromone-standardized, aloe-based composition, could potentially be used as a natural product option to facilitate the maintenance of healthy blood glucose levels.

Role of subcutaneous adipose tissue in the pathogenesis of insulin resistance

Burden of obesity has increased significantly in the United States over last few decades. Association of obesity with insulin resistance and related cardiometabolic problems is well established. Traditionally, adipose tissue in visceral fat depot has been considered a major culprit in development of insulin resistance. However, growing body of the literature has suggested that adipose tissue in subcutaneous fat depot, not only due to larger volume but also due to inherent functional characteristics, can have significant impact on development of insulin resistance. There are significant differences in functional characteristics of subcutaneous abdominal/truncal versus gluteofemoral depots. Decreased capacity for adipocyte differentiation and angiogenesis along with adipocyte hypertrophy can trigger vicious cycle of inflammation in subcutaneous adipose tissue and subsequent ectopic fat deposition. It is important to shift focus from fat content to functional heterogeneity in adipose tissue depots to better understand the relative role of subcutaneous adipose tissue in metabolic complications of obesity. Therapeutic lifestyle change continues to be the most important intervention in clinical practice at any level of increased adiposity. Future pharmaceutical interventions aimed at improving adipose tissue function in various subcutaneous depots have potential to help maintain adequate insulin sensitivity and reduce risk for development of insulin resistance complications.