Exercise Training Combined with Calanus Oil Supplementation Improves the Central Cardiodynamic Function in Older Women.

The aim of this study was to investigate the possible beneficial effects of exercise training (ET) with omega-3/Calanus oil supplementation on cardiorespiratory and adiposity parameters in elderly women. Fifty-five women (BMI: 19-37 kg/m2, 62-80 years old) were recruited and randomly assigned to the 4 month intervention with ET and omega-3 supplementation (Calanus oil, ET-Calanus) or ET and the placebo (sunflower oil; ET-Placebo). The body composition was determined by dual-energy X-ray absorptiometry (DXA), and cardiorespiratory parameters were measured using spiroergometry and PhysioFlow hemodynamic testing. Both interventions resulted in an increased lean mass whereas the fat mass was reduced in the leg and trunk as well as the android and gynoid regions. The content of trunk fat (in percent of the total fat) was lower and the content of the leg fat was higher in the ET-Calanus group compared with the ET-Placebo. Although both interventions resulted in similar improvements in cardiorespiratory fitness (VO2max), it was explained by an increased peripheral oxygen extraction (a-vO2diff) alone in the ET-Placebo group whereas increased values of both a-vO2diff and maximal cardiac output (COmax) were observed in the ET-Calanus group. Changes in COmax were associated with changes in systemic vascular resistance, circulating free fatty acids, and the omega-3 index. In conclusion, Calanus oil supplementation during a 4 month ET intervention in elderly women improved the cardiorespiratory function, which was due to combined central and peripheral cardiodynamic mechanisms.

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.

Hybrid and Model-Based Iterative Reconstruction Influences the Volumetry of Visceral and Subcutaneous Adipose Tissue on Ultra-Low-Dose CT.

OBJECTIVE: The aim of this study was to compare three different reconstruction algorithms for the volumetry of the visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) on ultra-low-dose computed tomography (CT) images. METHODS: Thirty-seven male patients underwent ultra-low-dose CT at the level of the fourth lumbar vertebra (22.5 mm in z-axis). The acquisitions were reconstructed in 5-mm slices with 50% overlap using filtered back projection (FBP), hybrid iterative reconstruction (HIR), and iterative model-based reconstruction (IMR) techniques. The volume of VAT and SAT was measured using an interactive seed-growing segmentation and by thresholding (-30 to -190 HU). RESULTS: The volume of SAT measured by the interactive method was smaller in FBP compared with both HIR (P = 0.0011) and IMR (P = 0.0034), and the volume of VAT was greater in IMR compared with HIR (P = 0.0253) or FBP (P = 0.0065). Using the thresholding method, IMR volumes of VAT were greater compared with HIR (P < 0.0001), and volumes of SAT were greater compared with both HIR and FBP (both P ≤ 0.0001). The VAT to SAT ratio was greater in IMR compared with HIR or FBP (both P < 0.0001). CONCLUSIONS: There are significant differences among FBP, HIR, and IMR in the volumetry of SAT and VAT, their ratios, and attenuation measured on ultra-low-dose images.

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.

Effect of Calanus Oil Supplementation and 16 Week Exercise Program on Selected Fitness Parameters in Older Women.

We investigated changes in functional fitness after an exercise program in combination with Calanus oil supplementation, a novel source of bioactive lipids rich in wax esters with omega-3 polyunsaturated fatty acid (n-3 PUFA). Fifty-five healthy sedentary women aged 65-80 (mean age 70.9 ± 3.9 years, BMI 27.24 ± 3.9 kg m-2, VO2peak 19.46 ± 3.7 ml kg-1 min-1) were enrolled in the study. The participants were divided into two groups: exercise training plus Calanus Oil supplementation (n = 28) or exercise plus placebo (sunflower oil) supplementation (n = 27). The exercise intervention program was completed by 53 participants and contained functional circuit training (twice a week, 45 min plus 15 min of stretching and balance training) and Nordic walking (once a week, 60 min) for 16 weeks. Senior fitness test, exercise stress test on bicycle ergometer, hand-grip, and body composition were evaluated before and after the program. Our results show that functional fitness and body composition improved following the interventional exercise program, but for most of the parameters there was no synergic effect of supplementing n-3 PUFA-rich Calanus oil. In comparison to the placebo group, the group with Calanus supplementation experienced significantly higher improvement of functional strength of lower body which was evaluated by the chair stand test. Supplementation with Calanus may have a synergic effect with exercise on functional strength of the lower body in the elderly.

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.

Circulating Monocyte and Lymphocyte Populations in Healthy First-Degree Relatives of Type 2 Diabetic Patients at Fasting and during Short-Term Hyperinsulinemia.

AIM: The development of type 2 diabetes (T2DM) is associated with disturbances of immune status that may be reflected by alterations of the profile of circulating immune cells. In order to study whether there exists genetic predisposition to these alterations, we investigated the relative content of circulating monocyte and lymphocyte subpopulations at fasting condition and upon stimulation by short-term hyperinsulinemia in nondiabetic first-degree relatives (FDR) of T2DM patients and in control subjects. MATERIALS AND METHODS: 19 nondiabetic (FDR) and 19 control subjects without a family history of diabetes (all men) matched for age and BMI underwent 2-hour hyperinsulinemic-euglycemic clamp. Blood samples taken before and at the end of the clamp were used for the flow cytometry analysis of lymphocyte and monocyte populations and for the assessment of cytokine levels. RESULTS: At fasting conditions, FDR showed a higher CD4/CD8 ratio of peripheral lymphocytes, a higher percentage of Th17 lymphocytes, and a lower content of intermediate monocytes when compared to controls. The CD4/CD8 ratio correlated with fat mass, insulin, and HOMA-IR in the entire group of subjects. Hyperinsulinemia decreased a relative content of peripheral CD4+ and increased a relative content of CD8+ T lymphocytes, thus decreasing the CD4/CD8 ratio by 18-22% in both groups of subjects. In FDR but not in controls, the decrease of CD4+ T lymphocyte content was partially based on the decrease of TH2 and TH17 lymphocyte subpopulations. In control subjects but not in FDR, the number of intermediate monocytes has declined in response to hyperinsulinemia. CONCLUSION: The alterations of the CD4/CD8 lymphocyte ratio, relative content of TH17 cells, and intermediate monocytes in FDR are features of genetic predisposition to T2DM and may play a role in pathogenesis of T2DM. Short-term hyperinsulinemia affected mostly the immune cell populations deregulated in FDR subjects, which suggests important interplay between immune system homeostasis and insulin levels.

Apolipoprotein M: a novel adipokine decreasing with obesity and upregulated by calorie restriction.

BACKGROUND: The adipose tissue (AT) is a secretory organ producing a wide variety of factors that participate in the genesis of metabolic disorders linked to excess fat mass. Weight loss improves obesity-related disorders. OBJECTIVES: Transcriptomic studies on human AT, and a combination of analyses of transcriptome and proteome profiling of conditioned media from adipocytes and stromal cells isolated from human AT, have led to the identification of apolipoprotein M (apoM) as a putative adipokine. We aimed to validate apoM as novel adipokine, investigate the relation of AT APOM expression with metabolic syndrome and insulin sensitivity, and study the regulation of its expression in AT and secretion during calorie restriction-induced weight loss. METHODS: We examined APOM mRNA level and secretion in AT from 485 individuals enrolled in 5 independent clinical trials, and in vitro in human multipotent adipose-derived stem cell adipocytes. APOM expression and secretion were measured during dieting. RESULTS: APOM was expressed in human subcutaneous and visceral AT, mainly by adipocytes. ApoM was released into circulation from AT, and plasma apoM concentrations correlate with AT APOM mRNA levels. In AT, APOM expression inversely correlated with adipocyte size, was lower in obese compared to lean individuals, and reduced in subjects with metabolic syndrome and type 2 diabetes. Regardless of fat depot, there was a positive relation between AT APOM expression and systemic insulin sensitivity, independently of fat mass and plasma HDL cholesterol. In human multipotent adipose-derived stem cell adipocytes, APOM expression was enhanced by insulin-sensitizing peroxisome proliferator-activated receptor agonists and inhibited by tumor necrosis factor α, a cytokine that causes insulin resistance. In obese individuals, calorie restriction increased AT APOM expression and secretion. CONCLUSIONS: ApoM is a novel adipokine, the expression of which is a hallmark of healthy AT and is upregulated by calorie restriction. AT apoM deserves further investigation as a potential biomarker of risk for diabetes and cardiovascular diseases.

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.

Interaction between hormone-sensitive lipase and ChREBP in fat cells controls insulin sensitivity.

Impaired adipose tissue insulin signalling is a critical feature of insulin resistance. Here we identify a pathway linking the lipolytic enzyme hormone-sensitive lipase (HSL) to insulin action via the glucose-responsive transcription factor ChREBP and its target, the fatty acid elongase ELOVL6. Genetic inhibition of HSL in human adipocytes and mouse adipose tissue results in enhanced insulin sensitivity and induction of ELOVL6. ELOVL6 promotes an increase in phospholipid oleic acid, which modifies plasma membrane fluidity and enhances insulin signalling. HSL deficiency-mediated effects are suppressed by gene silencing of ChREBP and ELOVL6. Mechanistically, physical interaction between HSL, independent of lipase activity, and the isoform activated by glucose metabolism ChREBPα impairs ChREBPα translocation into the nucleus and induction of ChREBPß, the isoform with high transcriptional activity that is strongly associated with whole-body insulin sensitivity. Targeting the HSL-ChREBP interaction may allow therapeutic strategies for the restoration of insulin sensitivity.

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.

[Adaptation of adipose tissue to weight-reduction energy-restricted diet in obese individuals]. / Adaptace tukové tkáne na redukcní nízkoenergetickou dietu u obézních jedincu.

Obesity is associated with a number of metabolic disorders that lead to the development of type 2 diabetes, hyperlipidemia and ultimately cardiovascular diseases. An important role in the pathogenesis of metabolic disorders accompanying obesity is probably played by the alterations of adipose tissue characteristics: metabolic, endocrine and immune functions. The key component of obesity treatment, the weight-reduction energy-restricted diet, leads not only to the reduction of weight (specifically fat mass), but also to correction of obesity accompanying metabolic disorders. The mechanisms which mediate the metabolic effect of the weight-reduction energy-restricted diet, are unclear. It can be assumed that the weight-reduction diet "corrects" the impaired functions of the obese individuals adipose tissue and, subsequently, of the resulting metabolic disorders. The following text presents an overview of the changes of morphological and functional characteristics of adipose tissue that are induced by weight-reduction energy-restricted diets in obese individuals: the energy-restricted diet and the associated weight reduction cause a change in the size and differentiation of adipocytes, a change of metabolic functions, primarily of the regulation of adipose tissue lipolysis and lipogenesis, change in the regulation of endocrine functions and, finally, they lead to the change in the immune function indicators, i.e. adipose tissue infiltration with immune cells and secretion of a spectrum of cytokines. The knowledge about the mechanisms of favourable metabolic effects of energy-restricted diets may lead to an advancement in non-pharmacological procedures of therapy for obesity and its complications, and, in the longer, term to the development of new therapeutic pharmacological procedures.Key words: energy-restricted diet - obesity - weight reduction - adipose tissue.

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 ß-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.

Irf5 deficiency in macrophages promotes beneficial adipose tissue expansion and insulin sensitivity during obesity.

Accumulation of visceral adipose tissue correlates with elevated inflammation and increased risk of metabolic diseases. However, little is known about the molecular mechanisms that control its pathological expansion. Transcription factor interferon regulatory factor 5 (IRF5) has been implicated in polarizing macrophages towards an inflammatory phenotype. Here we demonstrate that mice lacking Irf5, when placed on a high-fat diet, show no difference in the growth of their epididymal white adipose tissue (epiWAT) but they show expansion of their subcutaneous white adipose tissue, as compared to wild-type (WT) mice on the same diet. EpiWAT from Irf5-deficient mice is marked by accumulation of alternatively activated macrophages, higher collagen deposition that restricts adipocyte size, and enhanced insulin sensitivity compared to epiWAT from WT mice. In obese individuals, IRF5 expression is negatively associated with insulin sensitivity and collagen deposition in visceral adipose tissue. Genome-wide analysis of gene expression in adipose tissue macrophages highlights the transforming growth factor ß1 (TGFB1) gene itself as a direct target of IRF5-mediated inhibition. This study uncovers a new function for IRF5 in controlling the relative mass of different adipose tissue depots and thus insulin sensitivity in obesity, and it suggests that inhibition of IRF5 may promote a healthy metabolic state during this condition.

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.

Stress of endoplasmic reticulum modulates differentiation and lipogenesis of human adipocytes.

BACKGROUND: Adipocytes are cells specialized for storage of neutral lipids. This storage capacity is dependent on lipogenesis and is diminished in obesity. The reason for the decline in lipogenic activity of adipocytes in obesity remains unknown. Recent data show that lipogenesis in liver is regulated by pathways initiated by endoplasmic reticulum stress (ERS). Thus, we aimed at investigating the effect of ERS on lipogenesis in adipose cells. METHODS: Preadipocytes were isolated from subcutaneous abdominal adipose tissue from obese volunteers and in vitro differentiated into adipocytes. ERS was induced pharmacologically by thapsigargin (TG) or tunicamycin (TM). Activation of Unfolded Protein Response pathway (UPR) was monitored on the level of eIF2α phosphorylation and mRNA expression of downstream targets of UPR sensors. Adipogenic and lipogenic capacity was evaluated by Oil Red O staining, measurement of incorporation of radio-labelled glucose or acetic acid into lipids and mRNA analysis of adipogenic/lipogenic markers. RESULTS: Exposition of adipocytes to high doses of TG (100 nM) and TM (1 µg/ml) for 1-24 h enhanced expression of several UPR markers (HSPA5, EDEM1, ATF4, XBP1s) and phosphorylation of eIF2α. This acute ERS substantially inhibited expression of lipogenic genes (DGAT2, FASN, SCD1) and glucose incorporation into lipids. Moreover, chronic exposure of preadipocytes to low dose of TG (2.5 nM) during the early phases of adipogenic conversion of preadipocytes impaired both, lipogenesis and adipogenesis. On the other hand, chronic low ERS had no apparent effect on lipogenesis in mature adipocytes. CONCLUSIONS: Acute ERS weakened a capacity of mature adipocytes to store lipids and chronic ERS diminished adipogenic potential of preadipocytes.

Effect of short-term hyperglycemia on adipose tissue fluxes of selected cytokines in vivo during multiple phases of diet-induced weight loss in obese women.

CONTEXT: Hyperglycemia is suggested to be one of the drivers of the proinflammatory state observed in obese and diabetic patients. OBJECTIVES: The objectives of the study was to investigate whether sc abdominal adipose tissue (scAT) could be one of the important sources of proinflammatory cytokines released in response to short-term hyperglycemia and whether this secretion capacity could be influenced by weight loss. DESIGN, PATIENTS, AND INTERVENTIONS: Output of cytokines and proteins of acute phase from scAT in response to a 3-hours hyperglycemic clamp was evaluated in nine obese women in vivo using Fick's principle. Moreover, the output of cytokines was analyzed during a multiphase dietary intervention consisting of 1 month on a very low-calorie diet and subsequent 5-month weight-stabilization phase. MAIN OUTCOME MEASURE(S): The levels of cytokines and proteins of acute phase [IL-6, IL-8, IL-1 receptor antagonist (IL-1Ra), TNF-α, monocyte chemoattractant protein-1 (MCP-1), serum amyloid A, and C-reactive protein] in arterial and venous plasma were measured during each dietary phase. The insulin sensitivity of scAT in respect to the antilipolytic effect of insulin during the clamp was assessed. RESULTS: Hyperglycemia increased the output of cytokines IL-6, MCP-1, and IL-1Ra from scAT. This effect had a tendency to be reduced after weight loss. The output of other proinflammatory substances from scAT into circulation was not detected. The diet-induced weight loss was associated with the improvement of antilipolytic insulin sensitivity in scAT. CONCLUSIONS: The results suggest that short-term hyperglycemia induces an increase of the output of cytokines IL-6, IL-1Ra, and MCP-1 from adipose tissue, and this deleterious hyperglycemia effect may be attenuated by the diet-induced weight reduction. This lowered responsiveness of the inflammation-related system may be an important feature of the weight reduction-induced improvement of the metabolic status of obese prediabetic individuals.

Immune cell Toll-like receptor 4 mediates the development of obesity- and endotoxemia-associated adipose tissue fibrosis.

Adipose tissue fibrosis development blocks adipocyte hypertrophy and favors ectopic lipid accumulation. Here, we show that adipose tissue fibrosis is associated with obesity and insulin resistance in humans and mice. Kinetic studies in C3H mice fed a high-fat diet show activation of macrophages and progression of fibrosis along with adipocyte metabolic dysfunction and death. Adipose tissue fibrosis is attenuated by macrophage depletion. Impairment of Toll-like receptor 4 signaling protects mice from obesity-induced fibrosis. The presence of a functional Toll-like receptor 4 on adipose tissue hematopoietic cells is necessary for the initiation of adipose tissue fibrosis. Continuous low-dose infusion of the Toll-like receptor 4 ligand, lipopolysaccharide, promotes adipose tissue fibrosis. Ex vivo, lipopolysaccharide-mediated induction of fibrosis is prevented by antibodies against the profibrotic factor TGFß1. Together, these results indicate that obesity and endotoxemia favor the development of adipose tissue fibrosis, a condition associated with insulin resistance, through immune cell Toll-like receptor 4.