The role of adipogenic capacity and dysfunctional subcutaneous adipose tissue in the inheritance of type 2 diabetes mellitus: cross-sectional study

OBJECTIVE

This study tested the hypothesis that limited subcutaneous adipose tissue (SAT) expansion represents a primary predisposition to the development of type 2 diabetes mellitus (T2DM), independent of obesity, and identified novel markers of SAT dysfunction in the inheritance of T2DM.

METHODS

First-degree relatives (FDR) of T2DM patients (n = 19) and control individuals (n = 19) without obesity (fat mass < 25%) were cross-sectionally compared. Body composition (bioimpedance, computed tomography) and insulin sensitivity (IS; oral glucose tolerance test, clamp) were measured. SAT obtained by needle biopsy was used to analyze adipocyte size, lipidome, mRNA expression, and inflammatory markers. Primary cultures of adipose precursors were analyzed for adipogenic capacity and metabolism.

RESULTS

Compared with control individuals, FDR individuals had lower IS and a higher amount of visceral fat. However, SAT-derived adipose precursors did not differ in their ability to proliferate and differentiate or in metabolic parameters (lipolysis, mitochondrial oxidation). In SAT of FDR individuals, lipidomic and mRNA expression analysis revealed accumulation of triglycerides containing polyunsaturated fatty acids and increased mRNA expression of lysyl oxidase (LOX). These parameters correlated with IS, visceral fat accumulation, and mRNA expression of inflammatory and cellular stress genes.

CONCLUSIONS

The intrinsic adipogenic potential of SAT is not affected by a family history of T2DM. However, alterations in LOX mRNA and polyunsaturated fatty acids in triacylglycerols are likely related to the risk of developing T2DM independent of obesity.

Calanus Oil Supplementation Does Not Further Improve Short-Term Memory or Brain-Derived Neurotrophic Factor in Older Women Who Underwent Exercise Training

Purpose

In our study, we examined changes in short-term episodic memory and brain-derived neurotrophic factor (BDNF) in women after an exercise program alone or in combination with omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementation.

Patients and Methods

Fifty-five healthy elderly women (65–80 years) were randomly split into two groups: in the first group were women attending an exercise program while taking wax esters-rich oil (Calanus) supplementation (n = 28) and in the other group were women undergoing the same exercise program while taking placebo (n = 27). The 16-week exercise program consisted of functional circuit training (twice a week) and Nordic walking lessons (once a week). Short-term episodic memory was evaluated by the Czech screening Test “Pojmenování OBrázků A jejich Vybavení” (POBAV) baseline and after the program lasting 16 weeks.

Results

Our results show that short-term memory significantly improved following the exercise program, but there was no added value in using n-3 PUFA supplements. BDNF values did not differ between baseline and follow-up in either group. However, there was a statistically significant positive relationship between relative change (%) in the POBAV test and VO₂peak in the placebo group (r = 0.49).

Conclusion

Despite the added value of n-3 PUFA supplementation not being proven, our results may strengthen the importance of physical activity in averting age-related memory decline and dementia.

Exercise Training Reduces Inflammation of Adipose Tissue in the Elderly: Cross-Sectional and Randomized Interventional Trial

CONTEXT

Metabolic disturbances and a pro-inflammatory state associated with aging and obesity may be mitigated by physical activity or nutrition interventions.

OBJECTIVE

The aim of this study is to assess whether physical fitness/exercise training (ET) alleviates inflammation in adipose tissue (AT), particularly in combination with omega-3 supplementation, and whether changes in AT induced by ET can contribute to an improvement of insulin sensitivity and metabolic health in the elderly.

DESIGN, PARTICIPANTS, MAIN OUTCOME MEASURES

The effect of physical fitness was determined in cross-sectional comparison of physically active/physically fit (trained) and sedentary/less physically fit (untrained) older women (71 ± 4 years, n = 48); and in double-blind randomized intervention by 4 months of ET with or without omega-3 (Calanus oil) supplementation (n = 55). Physical fitness was evaluated by spiroergometry (maximum graded exercise test) and senior fitness tests. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp. Samples of subcutaneous AT were used to analyze mRNA gene expression, cytokine secretion, and immune cell populations.

RESULTS

Trained women had lower mRNA levels of inflammation and oxidative stress markers, lower relative content of CD36+ macrophages, and higher relative content of γδT-cells in AT when compared with untrained women. Similar effects were recapitulated in response to a 4-month ET intervention. Content of CD36+ cells, γδT-cells, and mRNA expression of several inflammatory and oxidative stress markers correlated to insulin sensitivity and cardiorespiratory fitness.

CONCLUSIONS

In older women, physical fitness is associated with less inflammation in AT. This may contribute to beneficial metabolic outcomes achieved by ET. When combined with ET, omega-3 supplementation had no additional beneficial effects on AT inflammatory characteristics.

Lymphatic drainage affects lipolytic activity of femoral adipose tissue in women

It has been shown that many molecules released by adipose tissue (AT) into interstitial fluid can reach the bloodstream preferentially via lymphatic system. Worsened lymphatic drainage may alter interstitial fluid (ISF) composition and thus affect microenvironment of adipocytes. Nevertheless, the effect of lymphatic drainage on AT functions remains unknown. Therefore, we analyzed the lipolytic activity of femoral AT in two groups of premenopausal women similar in adiposity but differing in the efficiency of lymphatic drainage of lower body as assessed by lymphoscintigraphy. Levels of lipolytic markers were assessed in plasma and ISF collected by skin blister technique in femoral area. In addition, microdialysis was used to monitor lipolysis of AT in vivo. Our results indicate that worsened lymphatic drainage is associated with lower in vivo lipolytic index and reduced lipolytic responsiveness of femoral AT to adrenergic stimuli. Thus, efficiency of lymphatic drainage appears to play a role in the regulation of AT metabolism. Accordingly, worsened lymphatic drainage could contribute to the resistance of lower body AT to intentional weigh loss.

Signs of Deregulated Gene Expression Are Present in Both CD14+ and CD14- PBMC From Non-Obese Men With Family History of T2DM

AIM

Development of type 2 diabetes (T2DM) is associated with disturbances in immune and metabolic status that may be reflected by an altered gene expression profile of peripheral blood mononuclear cells (PBMC). To reveal a potential family predisposition to these alterations, we investigated the regulation of gene expression profiles in circulating CD14⁺ and CD14^- PBMC in fasting conditions and in response to oral glucose tolerance test (OGTT) in glucose tolerant first-degree relatives (FDR) of T2DM patients and in control subjects.

MATERIALS AND METHODS

This work is based on the clinical study LIMEX (NCT03155412). Non-obese 12 non-diabetic (FDR), and 12 control men without family history of diabetes matched for age and BMI underwent OGTT. Blood samples taken before and at the end of OGTT were used for isolation of circulating CD14⁺ and CD14^- PBMC. In these cells, mRNA levels of 94 genes related to lipid and carbohydrate metabolism, immunity, and inflammation were assessed by qPCR.

RESULTS

Irrespectively of the group, the majority of analyzed genes had different mRNA expression in CD14⁺ PBMC compared to CD14^- PBMC in the basal (fasting) condition. Seven genes (IRS1, TLR2, TNFα in CD14⁺ PBMC; ABCA1, ACOX1, ATGL, IL6 in CD14^- PBMC) had different expression in control vs. FDR groups. OGTT regulated mRNA levels of nine genes selectively in CD14⁺ PBMC and of two genes (ABCA1, PFKL) selectively in CD14^-PBMC. Differences in OGTT-induced response between FDR and controls were observed for EGR2, CCL2 in CD14⁺ PBMC and for ABCA1, ACOX1, DGAT2, MLCYD, and PTGS2 in CD14^- PBMC.

CONCLUSION

This study revealed a different impact of glucose challenge on gene expression in CD14⁺ when compared with CD14^- PBMC fractions and suggested possible impact of family predisposition to T2DM on basal and OGTT-induced gene expression in these PBMC fractions. Future studies on these putative alterations of inflammation and lipid metabolism in fractionated PBMC in larger groups of subjects are warranted.

Expression of lipogenic markers is decreased in subcutaneous adipose tissue and adipocytes of older women and is negatively linked to GDF15 expression

In aging, the capacity of subcutaneous adipose tissue (SAT) to store lipids decreases and this results in metabolically unfavorable fat redistribution. Triggers of this age-related SAT dysfunction may include cellular senescence or endoplasmic reticulum (ER) stress. Therefore, we compared lipogenic capacity of SAT between young and older women and investigated its relation to senescence and ER stress markers. Samples of SAT and corresponding SAT-derived primary preadipocytes were obtained from two groups of women differing in age (36 vs. 72 years, n = 15 each) but matched for fat mass. mRNA levels of selected genes (lipogenesis: ACACA, FASN, SCD1, DGAT2, ELOVL6; senescence: p16, p21, NOX4, GDF15; ER stress-ATF4, XBP1s, PERK, HSPA5, GADD34, HYOU1, CHOP, EDEM1, DNAJC3) were assessed by qPCR, protein levels of GDF15 by ELISA, and mitochondrial function by the Seahorse Analyzer. Compared to the young, SAT and in vitro differentiated adipocytes from older women exhibited reduced mRNA expression of lipogenic enzymes. Out of analyzed senescence and ER stress markers, the only gene, whose expression correlated negatively with the expression of lipogenic enzymes in both SAT and adipocytes, was GDF15, a marker of not only senescence but also mitochondrial dysfunction. In line with this, inhibition of mitochondrial ATP synthase in adipocytes strongly upregulated GDF15 while reduced expression of lipogenic enzymes. Moreover, adipocytes from older women had a tendency for diminished mitochondrial capacity. Thus, a reduced lipogenic capacity of adipocytes in aged SAT appears to be linked to mitochondrial dysfunction rather than to ER stress or accumulation of senescent cells.

Metformin Does Not Inhibit Exercise-Induced Lipolysis in Adipose Tissue in Young Healthy Lean Men

Objective: Metformin was shown to exert an antilipolytic action in adipose tissue (AT) that might mediate beneficial effects on lipid metabolism in diabetic patients. However, during exercise, the inhibition of induced lipolysis in AT would limit the energy substrate supply for working muscle. Thus, the aim of this study was to investigate whether metformin exerts inhibitory effect on exercise-induced lipolysis in subcutaneous adipose tissue (SCAT) (Moro et al., 2007) in humans. Approach: Ten healthy lean men underwent two exercise sessions consisting of 60 min of cycling on bicycle ergometer combined with (a) orally administered metformin and (b) metformin locally administered into SCAT. Microdialysis was used to assess lipolysis in situ in SCAT. Glycerol, metformin and lactate were measured in dialysate and plasma by enzyme colorimetric kits and capillary electrophoresis. Results: Metformin levels increased continuously in plasma during 3 h after oral administration, and peaked after 3.5 h (peak concentration 4 μg/ml). Metformin was detected in dialysate outflowing from SCAT and showed a similar time-course as that in plasma with the peak concentration of 1.3 μg/ml. The lipolytic rate in SCAT (assessed as glycerol release) increased in response to exercise (4.3 ± 0.5-fold vs. basal; p = 0.002) and was not suppressed either by local or oral metformin administration. The lactate levels increased in plasma and in dialysate from SCAT after 30-60 min of exercise (3.6-fold vs. basal; p = 0.015; 2.75-fold vs. basal; p = 0.002, respectively). No effect of metformin on lactate levels in SCAT dialysate or in plasma during exercise was observed. Conclusion: Metformin did not reduce the exercise-induced lipolysis in SCAT. This suggests that metformin administration does not interfere with the lipid mobilization and energy substrate provision during physical activity.

Comparison of Early (2 Days) and Later (28 Days) Response of Adipose Tissue to Very Low-Calorie Diet in Obese Women

CONTEXT

Beneficial metabolic effects of calorie restriction found in the early stage of hypocalorie diets may be caused by the modulation of metabolic and endocrine function of adipose tissue.

OBJECTIVE

The objective of the study was to compare metabolic and inflammation-related characteristics of sc adipose tissue (SAAT) in the early (2 d) and later (28 d) phase of a very low calorie diet (VLCD). Design, Setting, Intervention, and Patients: Seventeen moderately obese premenopausal women followed an 800 kcal/d VLCD for 28 days. Anthropometric measurements, blood sampling, and a biopsy of SAAT were performed before the diet and after 2 and 28 days of the VLCD.

MAIN OUTCOME MEASURE(S)

mRNA expression of 50 genes related to lipid metabolism, inflammation, and fibrosis were analyzed in SAAT. Secretion of adipokines was determined in SAAT explants and adipokines, fibroblast growth factor 21 (FGF21) and C-reactive protein were measured in plasma.

RESULTS

In the early phase of the VLCD, the expression of lipolytic genes was increased, whereas the expression of lipogenic genes was significantly suppressed. The inflammatory markers in SAAT remained unchanged. At the later phase, expression of genes involved in lipogenesis and β-oxidation was markedly suppressed, whereas the expression of inflammatory markers was increased. The changes of lipogenic genes after 28 days of the VLCD correlated with FGF21 changes.

CONCLUSION

The early and later phases of a VLCD differ with respect to metabolic and inflammatory responses in SAAT. The expression changes in SAAT in the early phase of the VLCD could not explain the effect of short calorie restriction on the improvement of insulin sensitivity. An interplay of SAAT with liver function during VLCD mediated by FGF21 might be suggested.

Acute hyperlipidemia initiates proinflammatory and proatherogenic changes in circulation and adipose tissue in obese women

BACKGROUND

Obesity represents a high risk factor for the development of atherosclerosis and is associated with a low-grade inflammation and activation of immune cells.

AIMS

The aim of our study was to investigate the effect of a short-term lipid infusion on immune cells in blood and subcutaneous abdominal adipose tissue (SAAT) in obese women.

METHODS

Seven-hour intravenous lipid/control infusions were performed in two groups of women (n = 15, n = 10, respectively). Before and at the end of the infusion, SAAT and blood samples were obtained and relative content and phenotype of immune cells were analyzed using flow cytometry. Analysis of immune cell markers, inflammation and angiogenesis markers was performed in SAAT by RT-PCR and in plasma by immunoassays.

RESULTS

Relative content of CD45+/14+ and CD45+/14+/16+ populations of monocytes was reduced in circulation by 21% (p = 0.004) and by 46% (p = 0.0002), respectively, in response to hyperlipidemia, which suggested the increased adhesion of these cells to endothelium. In line with this, the levels of sICAM and sVCAM in plasma were increased by 9.4% (p = 0.016), 11.8% (p = 0.008), respectively. In SAAT, the relative content of M2 monocyte/macrophages subpopulation CD45+/14+/206+/16+ decreased by 27% (p = 0.012) and subpopulations CD14+/CD206- and CD14/+TLR4+ cells increased (p = 0.026; p = 0.049, respectively). Intralipid infusion promoted an increase of mRNA levels in SAAT: RORC (marker of proinflammatory Th17 lymphocytes) by 43% (p = 0.048), MCP-1 (78%, p = 0.028) and VEGF (68.5%, p = 0.0001).

CONCLUSIONS

Acute hyperlipidemia induces a proinflammatory and proatherogenic response associated with altered relative content of immune cells in blood and SAAT in obese women.

Experimental hyperglycemia induces an increase of monocyte and T-lymphocyte content in adipose tissue of healthy obese women

Background/Objectives

Hyperglycemia represents one of possible mediators for activation of immune system and may contribute to worsening of inflammatory state associated with obesity. The aim of our study was to investigate the effect of a short-term hyperglycemia (HG) on the phenotype and relative content of immune cells in circulation and subcutaneous abdominal adipose tissue (SAAT) in obese women without metabolic complications.

Subjects/Methods

Three hour HG clamp with infusion of octreotide and control investigations with infusion of octreotide or saline were performed in three groups of obese women (Group1: HG, Group 2: Octreotide, Group 3: Saline, n=10 per group). Before and at the end of the interventions, samples of SAAT and blood were obtained. The relative content of immune cells in blood and SAAT was determined by flow cytometry. Gene expression analysis of immunity-related markers in SAAT was performed by quantitative real-time PCR.

Results

In blood, no changes in analysed immune cell population were observed in response to HG. In SAAT, HG induced an increase in the content of CD206 negative monocytes/macrophages (p<0.05) and T lymphocytes (both T helper and T cytotoxic lymphocytes, p<0.01). Further, HG promoted an increase of mRNA levels of immune response markers (CCL2, TLR4, TNFα) and lymphocyte markers (CD3g, CD4, CD8a, TBX21, GATA3, FoxP3) in SAAT (p<0.05 and 0.01). Under both control infusions, none of these changes were observed.

Conclusions

Acute HG significantly increased the content of monocytes and lymphocytes in SAAT of healthy obese women. This result suggests that the short-term HG can modulate an immune status of AT in obese subjects.