The adipocyte as an endocrine cell1

Anthropometric Development in Children: Possible Changes in Body Mass, Basal Metabolic Rate and Inflammatory Status

(1) Background: Worldwide, public health policies focus on studying dietary patterns and the related anthropometric changes in children. Their aim is to improve the measures meant to reduce global malnutrition rates. Our goal was to study the main changes in the inflammatory status related to anthropometric changes and total daily energy intake. (2) Methods: We tested the study hypothesis by analyzing serum IL-6 and IL-8 levels, cholesterol and triglycerides values, as well as total proteins and creatinine levels, RMR, and food journals in a sample of 160 healthy subjects aged between 6 and 12 years old. (3) Results: IL-6 was correlated with the skinfold values. Changes in the skinfolds were significantly correlated with total proteins and triglycerides. Both weight for age and height for age were related to the skinfold values. Through the BMR measurements, peak carbohydrate metabolism changed significantly based upon IL-6 values, which were significantly correlated with the respiratory coefficient values. Based on the basal metabolic rate, an increased IL-8 ratio was related to the RQ value. (4) Conclusions: Skinfolds have been significantly correlated with IL-6 and IL-8 levels. With changes in body weight, we encountered differences in both serum cholesterol and serum triglycerides values, unlike total proteins and creatinine, which failed to change.

Insulin Resistance and Colorectal Cancer Risk: the Role of Elevated Plasma Resistin Levels

PURPOSE

Given the important role of resistin in insulin resistance (IR) and obesity, as well as the associations between both IR and obesity and increased risk of colorectal cancer (CRC), we investigated whether plasma resistin levels were associated with CRC risk. Furthermore, the possible correlations between resistin and insulin, IR, and obesity in patients with CRC and controls were explored.

METHODS

This study was conducted as a case-control study and 170 subjects, including 88 controls and 82 cases with CRC, were enrolled and their plasma levels of glucoe, insulin, and resistin were measured using glucose oxidase or ELISA methods. Moreover, IR was calculated according to HOMA-IR index.

RESULTS

The cases with CRC had a higher HOMA-IR than the controls (1.8 ± 0.4 versus 1.4 ± 0.3, P < 0.001). Additionally, after the stratification of the cases with CRC by tumor site, higher levels of resistin and insulin, and a higher HOMA-IR in the cases with rectal cancer than in the controls were observed (resistin 5.9 ± 1.2 versus 5.4 ± 1.3, P = 0.043; insulin 5.9 ± 1.2 versus 5.4 ± 1.3, P = 0.039; HOMA- IR 1.9 ± 0.4 versus 1.3 ± 0.3, P < 0.001). Furthermore, resistin was positively correlated with insulin in the controls (r = 0.737, P < 0.001), the cases with CRC (r = 0.881, P < 0.001), the cases with colon cancer (r = 0.811, P < 0.001), and the cases with rectal cancer (r = 0.990, P < 0.001). All these differences remained significant after adjustment for confounding factors.

CONCLUSIONS

The findings of the present study reinforce the hypothesis that higher plasma levels of resistin in connection with insulin resistance play a role in susceptibility to colorectal, notably rectal, cancer. Nevertheless, further studies with bigger sample sizes are required to validate these findings.

Anti-inflammatory activity of elicited soybean (Glycine max) extract on Balb/C mice (Mus musculus) with high-fat and -fructose diet

Obesity causes adipocyte hypertrophy, which leads to cell death. Consequently, macrophages and lymphocytes infiltrate into the adipose tissue and elevate pro-inflammatory cytokine production through TLR activation. This study aimed to determine the efficacy of soybean extract, which was elicited by Saccharomyces cerevisiae and light, as an anti-inflammatory agent in mice with a high-fat and -fructose diet (HFFD). The elicited soybean extract (ESE) was administered orally to mice for four weeks after being given an HFFD for 20 weeks. Three different doses were used: (1) low-dose (78 mg/kg BW); (2) normal dose (104 mg/kg BW); and (3) high dose (130 mg/kg BW). HFFD mice model treated with simvastatin 2.8 mg/kg BW considered as drug control. After 24 weeks, the lymphocytes were isolated and the relative number of CD4⁺TLR3⁺ T, CD4⁺TLR4⁺ T, CD4⁺TNF-α⁺ T, and CD4⁺IFN-γ⁺ T cells were analysed using flow cytometry. The results showed that the HFFD mouse model had an increased number of CD4⁺TLR3⁺ T, CD4⁺TLR4⁺ T, CD4⁺TNF-α⁺ T, and CD4⁺IFN-γ⁺ T cells. ESE administration decreased the relative number of CD4⁺TLR3⁺ T, CD4⁺TLR4⁺ T, CD4⁺TNF-α⁺ T, and CD4⁺IFN-γ⁺ T cells. The normal dose of ESE is the most effective dose in suppressing inflammation compared to positive controls. ESE 104 mg/kg BW can be considered as an alternative herbal medicine that may suppress inflammation in HFFD mice.

Parabens and Their Relation to Obesity

Parabens are a group of chemicals used as preservatives in the food, cosmetic and pharmaceutical industries. They are known to possess estrogenic effects, and therefore have been classified as endocrine disruptors. In addition to the classical endocrine organs, other tissues have endocrine activity, including adipose tissue. Several chemicals are known to cause obesogenic effects, and parabens are currently being studied in this context. The aim of this study was to investigate the possible connections of paraben exposure and obesity. Blood plasma from 27 healthy women was collected during their menstrual cycle. Basal anthropometric measures, levels of parabens (methylparaben, ethylparaben and propylparaben), adipokines (adiponectin, adipsin, leptin, resistin and visfatin) and hormones affecting energy balance and metabolic health (c-peptide, ghreline, GIP, GLP-1, glucagon, insulin, PAI-1) were measured. A Kolmogorov-Smirnov test showed higher methylparaben and propylparaben levels in women with BMI 25-34.9 compared to those with BMI 18.5-24.9. Plasma levels of methylparaben as well as the sum of parabens were positively associated with the plasma adipsin levels. Negative associations for methylparaben were found for glucagon, leptin and PAI-1. In accordance with other experimental studies we observed important associations of methylparaben and hormones affecting energy balance and metabolic health, indicating its obesogenic potential.

Rainbow trout (Oncorhynchus mykiss) adipose tissue undergoes major changes in immune gene expression following bacterial infection or stimulation with pro-inflammatory molecules

In mammals, visceral adipose is increasingly seen as playing an important role in immune function with numerous pro-inflammatory, anti-inflammatory and immune-modulating proteins and peptides being identified in adipocytes. Adipose is also now known as a tissue that has an important role in the regulation of peritoneal immune responses. Despite this, only lately has consideration been given to visceral adipose as an important immune tissue in fish, especially in the context of intraperitoneal vaccination. The present study demonstrates that fish visceral adipose is capable of expressing a large range of immune molecules in response to stimulation with a live bacterium (A. salmonicida), a bacterial PAMP (Y. ruckeri flagellin), and the pro-inflammatory cytokines IL-1β, TNF-α3 and IFN-γ. Following infection and stimulation with flagellin and IL-1β a large upregulation of pro-inflammatory and antimicrobial molecules was seen, with a high degree of overlap. TNF-α treatment affected relatively few genes and the effects were more modest. IFN-γ had the smallest impact on adipose but IFN-γ inducible genes showed some of the largest effects. Overall, it is clear that adipose tissue should be considered an active immune site in fish, capable of participating in and influencing immune responses.

Triglycerides/High density lipoprotein cholesterol ratio as a cardiometabolic risk marker in children and adolescents from Mérida city, Venezuela

OBJECTIVE

To determine the behavior of the triglycerides/HDL-cholesterol ratio (TG/HDL) as a cardiometabolic risk marker in children and adolescents from Mérida, Venezuela.

METHODS

A total of 1292 children and adolescents aged 7-18 years who attended educational institutions in the Libertador Municipality were enrolled into this study. Anthropometric measurements and blood pressure values were recorded. Fasting blood glucose, insulin and lipid levels were measured. The TG/HDL ratio, HOMA-IR, and QUICKI indexes were calculated. Subjects were categorized as with and without cardiometabolic risk based on the presence or absence of 2or more risk factors. Cut-off points for the TG/HDL ratio were determined by constructing ROC curves.

RESULTS

Significantly higher mean TG/HDL ratios were found in pubertal (2.2 ± 1.7) as compared to prepubertal subjects (1.8 ± 1.5; P=.001), with no sex differences. Two or more risk factors were found in 14.7% (n=192) of the participants, in whom TG/HDL ratios were significantly higher as compared to those with no risk (3.5±2.9 versus 1.6±0.8 in prepubertal and 4.1 ± 3.5 versus 1.8 ± 0.9 in pubertal subjects; P=.0001). According to cardiometabolic risk, cut-off points for the TG/HDL ratio of 1.8 and 2.5 were found for prepubertal and pubertal children respectively. These cut-off points showed risks (odds ratio) higher than 2.5 for conditions such as metabolic syndrome, elevated non-HDL-C, abdominal obesity, and elevated HOMA-IR.

CONCLUSION

In this sample of children and adolescents, an elevated TG/HDLc ratio was found to be a good marker for predicting cardiometabolic risk.

In vitro structure-specific Zn(II)-induced adipogenesis and structure-function bioreactivity correlations

The advent of Zn(II) metallodrugs in metabolic syndrome pathologies generates a strong challenge toward synthetic endeavors targeting well-defined, atoxic and biologically active binary/ternary species of Zn(II). Proper formulation of that metal ion's coordination sphere sets the stage for construction of appropriately configured Schiff ligands based on tromethamine and variably modified vanillin core components. The arising Schiff ligands react with Zn(II) in a defined stoichiometry, thereby delivering new binary Zn(II)-L species with defined physicochemical properties. Analytical (elemental), spectroscopic (FT-IR, Thermogravimetric Analysis) and crystallographic techniques attest to the distinct nature of the derived binary-ternary materials, bearing defined Zn(II):L molecular stoichiometry, variable nuclearity, charge, bulk and balance mix of hydrophilicity-hydrophobicity, thereby providing the physicochemical profile based on which biological studies could ensue. The structurally based selection of species was applied onto in vitro 3T3-L1 cultures, essentially exploring toxicity, migration, morphology, cell differentiation and maturation. The systematic effort toward comparative work on appropriately defined Zn(II) species and insulin in inducing adipogenesis reveals the salient structural features in the Schiff family of ligands configuring Zn(II) so as to promote complex formation sufficient to engage biomolecular targets during the process of initiation and maturation. Molecular targets of importance in adipogenesis were examined under the influence of Zn(II) and their expression levels suggest the structural composition that a Zn(II) ion might have to optimally pursue cell differentiation. Thus, a well-defined selection of binary Zn(II)-L species is tightly associated with the incurred bioactivity, thereby setting the stage for the development of efficient Zn(II) metallodrugs to combat Diabetes mellitus II.

Microglia activation due to obesity programs metabolic failure leading to type two diabetes

Obesity is an energy metabolism disorder that increases susceptibility to the development of metabolic diseases. Recently, it has been described that obese subjects have a phenotype of chronic inflammation in organs that are metabolically relevant for glucose homeostasis and energy. Altered expression of immune system molecules such as interleukins IL-1, IL-6, IL-18, tumor necrosis factor alpha (TNF-α), serum amyloid A (SAA), and plasminogen activator inhibitor-1 (PAI-1), among others, has been associated with the development of chronic inflammation in obesity. Chronic inflammation modulates the development of metabolic-related comorbidities like metabolic syndrome (insulin resistance, glucose tolerance, hypertension and hyperlipidemia). Recent evidence suggests that microglia activation in the central nervous system (CNS) is a priority in the deregulation of energy homeostasis and promotes increased glucose levels. This review will cover the most significant advances that explore the molecular signals during microglia activation and inflammatory stage in the brain in the context of obesity, and its influence on the development of metabolic syndrome and type two diabetes.

The adipogenic potential of Cr(III). A molecular approach exemplifying metal-induced enhancement of insulin mimesis in diabetes mellitus II

Insulin resistance is identified through numerous pathophysiological conditions, such as Diabetes mellitus II, obesity, hypertension and other metabolic syndromes. Enhancement of insulin action and\or its complete replacement by insulin-enhancing or insulin-mimetic agents seems to improve treatment of metabolic diseases. Over the last decades, intensive research has targeted the investigation of such agents, with chromium emerging as an important inorganic cofactor involved in the requisite metabolic chemistry. Chromium in its trivalent state has been shown to play a central role in carbohydrate metabolism by enhancing insulin signaling, action, and thus the sensitivity of insulin-sensitive tissues. A very likely link between diabetes and obesity is the adipose tissue, which stores energy in the form of triglycerides and releases free fatty acids. To date, there is paucity of information on the exact mechanism of the chromium effect concerning insulin-activated molecular paths, such as adipogenesis. The aim of the present study is to delve into such an effect by employing a well-defined form of chromium (Cr(III)-citrate) on the a) survival of pre- and mature adipocytes (3T3-L1), b) endogenous cell motility, and c) insulin-enhancing adipogenic capacity. The emerging results suggest that Cr(III)-citrate a) is (a)toxic in a concentration- and time-dependent manner, b) has no influence on cell motility, c) can induce 3T3-L1 pre-adipocyte differentiation into mature adipocytes through elevation of tissue specific biomarker levels (PPAR-γ, GLUT 4 and GCK), and d) exemplifies structurally-based metal-induced adipogenesis as a key process contributing to the development of future antidiabetic metallodrugs.

Levels of Adipokines and Some Steroids During the Menstrual Cycle

The cyclical effects of hormones during the menstrual cycle (MC) are not just responsible for driving ovulation, but also have significant influence on dietary intake and appetite, as well as psychological and behavioral changes. The aim of our study was to describe changes and relationships between the MC and selected steroids, adipokines and food intake-related hormones. Twenty-seven women with regular menstrual cycles were included in the study, and their hormonal spectrum was measured in regular intervals starting from the first day of their cycle. Classical changes in gonadotropins, estrogens and progesterone during the menstrual cycle are accompanied by less striking but significant changes in 17-hydroxyprogesterone and testosterone. No significant changes show dehydroepiandrosterone and its 7-oxygenated metabolites. Adipokines show a tendency to increase during ovulation, while ghrelin and resistin decrease. There is also a remarkable association of sex hormone-binding globulin on the day of the cycle. Our results demonstrate that changes to adipokines during the menstrual cycle are not substantial, but nonetheless can play a role in the changes of food intake described in the literature. Precise descriptions of physiological changes in healthy women are important in helping us understand the significance of the changes accompanying various pathological states.

Declined plasma sfrp5 concentration in patients with type 2 diabetes and latent autoimmune diabetes in adults

OBJECTIVE

Secreted frizzled-related protein 5 (sfrp5), like adiponectin, has been identified as a novel insulin-sensitising and anti-inflammatory adipokine. Our objective was to determine whether differences of circulating plasma sfrp5 concentration exist among type 2 diabetes (T2D), latent autoimmune diabetes in adults (LADA) and healthy population.

METHODS

Enzyme-linked immuno sorbent assay was employed to detect the circulating sfrp5 level in plasma, and other lab tests such as fasting glucose and creatinine were also examined. Correlation analysis between sfrp5 and characteristics of subjects was conducted IBM SPSS Statistics and GraphPad Prism.

RESULTS

Circulating sfrp5 level was significantly decreased in T2D and LADA patients plasma compared with that in healthy control (14.14±11.91ng/mL, 14.82±11.27ng/mL, 22.98±12.36ng/mL, respectively), although no differences was observed between LADA and T2D groups. Furthermore, we found sfrp5 was correlated with homeostasis model assessment of insulin resistance (HOMA-IR), diabetes duration and BMI. Finally we found sfrp5 was still negatively correlated with HOMA-IR after being adjusted for disease duration and BMI(r= -0.315, P< 0.05).

CONCLUSIONS

Our results support a role for SFRP5 as a protective factor in the pathogenesis of autoimmune diabetes and facilitate a novel aspect for diabetes research.

Association of four insulin resistance genes with type 2 diabetes mellitus and hypertension in the Chinese Han population

Insulin resistance plays an important role in the development of type 2 diabetes mellitus (T2DM) and hypertension. The purpose of the present study was to evaluate the association between four insulin resistance genes (ADIPOQ, LEPR, RETN, and TRIB3) and both T2DM and hypertension. A total of 768 Han Chinese subjects were recruited into this study, including 188 cases who had T2DM alone, 223 cases who had hypertension alone, 181 cases with both T2DM and hypertension, and 176 control subjects with neither T2DM nor hypertension. Twenty-three tag SNPs in four insulin resistance genes were genotyped and analyzed for association with T2DM and hypertension. One intron SNP (rs13306519) in LEPR and one 3′UTR SNP (rs1063537) in ADIPOQ demonstrated a significant association with T2DM (P = 0.024 and 0.014 respectively). Another intron SNP (rs12037879) in LEPR and a promoter region SNP (rs266729) in ADIPOQ were significantly associated with hypertension (P = 0.041 and 0.042, respectively). These associations survived the permutation test (P = 0.023, 0.018, 0.026, and 0.035, respectively). These associations were still found to be significant in the additive model after adjusting for potential confounding factors including age, sex, BMI, HDL, LDL, total cholesterol, and triglyceride levels (P = 0.024, 0.016, 0.04, and 0.043, respectively). No other gene variants were found to be significantly associated with T2DM or hypertension (P > 0.05). None of the studied gene variants were found to be significantly associated with T2DM+ hypertension (P > 0.05). A significant interaction was observed between two SNPs rs13306519 in LEPR and rs266729 in ADIPOQ for T2DM (P_int = 0.012, OR_int = 2.67) and hypertension (P_int = 0.0041, OR_int = 2.23). These findings suggest that variants in ADIPOQ and LEPR are risk factors for T2DM and hypertension in the Chinese population and that variants in RETN and TRIB3 are not major risk factors for these diseases.

Adiposopathy: how do diet, exercise and weight loss drug therapies improve metabolic disease in overweight patients?

An increase in bodyweight is generally associated with an increased risk of excessive fat-related metabolic diseases (EFRMD), including Type 2 diabetes mellitus, hypertension and dyslipidemia. However, not all patients who are overweight have EFRMD, and not all patients with EFRMD are significantly overweight. The adipocentric paradigm provides the basis for a unifying, pathophysiological process whereby fat gain in susceptible patients leads to fat dysfunction ('sick fat'), and wherein pathological abnormalities in fat function (adiposopathy) are more directly related to the onset of EFRMD than increases in fat mass (adiposity) alone. But just as worsening fat function worsens EFRMD, improved fat function improves EFRMD. Peroxisome proliferator-activated receptor-gamma agonists increase the recruitment, proliferation and differentiation of preadipocytes ('healthy fat') and cause apoptosis of hypertrophic and dysfunctional (including visceral) adipocytes resulting in improved fat function and improved metabolic parameters associated with EFRMD. Weight loss interventions, such as a hypocaloric diet and physical exercise, in addition to agents such as orlistat, sibutramine and cannabinoid receptor antagonists, may have favorable effects upon fat storage (lipogenesis and fat distribution), nutrient metabolism (such as free fatty acids), favorable effects upon adipose tissue factors involved in metabolic processes and inflammation, and enhanced 'cross-talk' with other major organ systems. In some cases, weight loss therapeutic agents may even affect metabolic parameters and adipocyte function independently of weight loss alone, suggesting that the benefit of these agents in improving EFRMD may go beyond their efficacy in weight reduction. This review describes how adiposopathy interventions may affect fat function, and thus improve EFRMD.

Effects of leptin and adiponectin on the growth of porcine myoblasts are associated with changes in p44/42 MAPK signaling

We hypothesized that both adiponectin and leptin affect the growth of porcine skeletal muscle cells, with fatty acids acting as modifiers in adipokine action and that both adipokines influence the gene expression of their receptors. Therefore, the objective of this study was to investigate the effects of recombinant adiponectin and leptin on cell number (DNA) and DNA synthesis rate with and without oleic acid supplementation, on cell death, and on key intracellular signaling molecules of proliferating porcine myoblasts in vitro. Moreover, the mRNA expression of genes encoding for the leptin and adiponectin receptors (LEPR, ADIPOR1, ADIPOR2) as affected by leptin or adiponectin was examined. Recombinant porcine adiponectin (40 μg/mL) and leptin (20 ng/mL) increased DNA synthesis rate, measured as [(3)H]-thymidine incorporation (P < 0.01), reduced cell viability in terms of lactate dehydrogenase release (P < 0.05), or lowered DNA content after 24 h (P < 0.05). In adiponectin-treated cultures, oleic acid supplementation increased DNA synthesis rate and reduced cell number in a dose-dependent manner (P < 0.05). Both adiponectin (P = 0.07) and leptin (P < 0.05) induced a transient activation of p44/42 mitogen-activated protein kinase (MAPK) after 15 min, followed by decreases after 60 and 180 min (P < 0.05). Adiponectin tended to increase c-fos activation (P = 0.08) and decreased p53 activation at 180 min (P = 0.03). Both adiponectin and leptin down-regulated the abundance of ADIPOR2 mRNA and, transiently, of LEPR mRNA (P < 0.05). In conclusion, adiponectin and leptin may adversely affect the growth of porcine myoblasts, which is related to p44/42 MAPK signaling and associated with changes in ligand receptor gene expression.

The brain–adipose axis: A review of involvement of molecules

Many molecules are involved in the regulation of feeding behavior, and they and their receptors are located in the brain hypothalamus and adipocytes. On the basis of evidence suggesting an association between the brain and adipose tissue, we propose the concept of the brain-adipose axis. This model consists of (l) the expression of endogenous molecules and/or their receptors in the hypothalamus and peripheral adipose tissue, (2) the function of these molecules as appetite regulators in the brain, (3) their existence in the general circulation as secreted proteins and (4) the physiological affects of these molecules on fat cell size and number. These molecules can be divided into two anorexigenic and orexigenic classes. In adipose tissue, all orexigenic molecules possess adipogenic activity, and almost all anorexigenic molecules suppress fat cell proliferation. Although the manner, in which they present in the circulating blood connect the brain and peripheral adipocytes, remains to be well-organized, these observations suggest the positive feedback axis affecting molecules in the hypothalamus and adipose tissue. Analysis of the disturbance and dysregulation of this axis might promote the development of new anti-obesity drugs useful in treating the metabolic syndrome.

Daily flaxseed consumption improves glycemic control in obese men and women with pre-diabetes: a randomized study

The study hypothesis was that fasting glucose, insulin, fructosamine, C-reactive protein, and interleukin-6 decrease and adiponectin increases with daily flaxseed consumption in overweight or obese individuals with pre-diabetes. In this randomized, cross-over study overweight or obese men and postmenopausal women (n = 25) with pre-diabetes consumed 0, 13, or 26 g ground flaxseed for 12 weeks. Glucose, insulin, homeostatic model assessment (HOMA-IR), and normalized percent of α-linolenic fatty acid (ALA) were significantly different by treatment (multiple analysis of variance, P = .036, P = .013, P = .008, P = .024 respectively). Paired t tests showed glucose decreased on the 13 g intervention compared to the 0 g period [13 g = -2.10 ± 1.66 mg/L (mean ± SEM), 0 g = 9.22 ± 4.44 mg/L, P = .036]. Insulin decreased on the 13 g intervention but not the 26 g (P = .021) and 0 g (P = .013) periods (13 g = -2.12 ± 1.00 mU/L, 26 g = 0.67 ± 0.84 mU/L, 0 g = 1.20 ± 1.16 mU/L). HOMA-IR decreased on the 13 g period but not on the 26 g (P = .012) and 0 g (P = .008) periods (13 g = -0.71 ± 0.31, 26 g = 0.27 ± 0.24, 0 g = 0.51 ± 0.35). The α-linolenic fatty acid decrease for the 0 g period was different than the 13 g (P = .024) and 26 g (P = .000) periods (13 g = 0.20 ± 0.04, 26 g = 0.35 ± 0.07, 0 g = -0.01 ± 0.07). Fructosamine, high sensitivity C-reactive protein, adiponectin, and high-sensitivity interleukin-6 had no significant differences. Flaxseed intake decreased glucose and insulin and improved insulin sensitivity as part of a habitual diet in overweight or obese individuals with pre-diabetes.

Adiponectin, leptin and ghrelin levels in obese adolescent girls with polycystic ovary syndrome

STUDY OBJECTIVE

To evaluate the differences in adipokines, namely adiponectin, leptin, and ghrelin, in obese adolescent girls with or without polycystic ovary syndrome (PCOS).

DESIGN

Case-control study.

SETTING

University hospital.

PARTICIPANTS

38 adolescent girls (age 15-20 years). Group I: 17 Obese adolescent girls with PCOS (BMI ≥ 30 kg/m(2)); Group II: Control group of 21 obese adolescent girls (BMI ≥ 30 kg/m(2)).

MAIN OUTCOME MEASURES

Adiponectin, leptin, and ghrelin measurements.

RESULTS

LH, LH/FSH, and cortisol levels were significantly higher in the obese PCOS girls compared to the obese controls (6.94 ± 3.28 vs 4.44 ± 1.79; 1.50 ± 0.72 vs 0.90 ± 0.36; 16.02 ± 4.28 vs 12.46 ± 5.29; P < .05, respectively). Adiponectin, leptin, and ghrelin levels were similar between the obese PCOS girls and the obese controls (11.13 ± 6.00 vs 15.26 ± 12.66; 23.66 ± 11.54 vs 23.11 ± 11.17; 665.69 ± 402.12 vs 650.22 ± 467.73, respectively). Adiponectin negatively correlated with BMI (r = -0.32; P = .04) and positively correlated with fasting glucose (r = 0.40; P = .01). Leptin positively correlated with BMI (r = 0.534; P = .001), estradiol (r = 0.354; P = .02), and TSH (r = 0.374; P = .02). No significant correlation was found between ghrelin and the test parameters.

CONCLUSION

Among obese adolescents with PCOS, adiponectin, and leptin levels do not seem to be determined by the existence of PCOS, while ghrelin presents no significant correlation.

Serum concentrations of adiponectin, leptin, resistin, ghrelin and insulin and their association with obesity indices in obese normo- and hypertensive patients - pilot study

INTRODUCTION

Hypertension often coexists with obesity. Adipokines, ghrelin and insulin play important roles in the pathogenesis of both diseases. The aim of this study was to compare adiponectin, leptin, resistin, insulin and ghrelin mean serum concentrations and insulin resistance (HOMA-IR) in normo- and hypertensive patients with obesity.

MATERIAL AND METHODS

ALL INCLUDED PATIENTS WERE DIVIDED ON THE FOLLOWING GROUPS: non-diabetic hypertensive patients with class I obesity (group A, n = 21) and class II/III obesity (group B, n = 10), and normotensive obese (class I)patients (group C, n = 7). Correlations between obesity indices (body mass index [BMI], waist-to-hip ratio [WHR], waist circumference [WC]), HOMA-IR, and hormone and adipokine serum levels were also analyzed.

RESULTS

Leptin level and HOMA-IR were significantly higher in group B compared to group C (9.74 ±3.88 ng/ml vs. 4.53 ±3.00 ng/ml; p < 0.02 and 3.30 ±1.59 vs. 1.65 ±0.41; p < 0.02, respectively). A negative correlation between WC and adiponectin level (R = -0.6275; p < 0.01) and a positive correlation between WC and insulin concentration (R = 0.5122; p< 0.05) as well as with HOMA-IR (R = 0.5228; p < 0.02) were found in group A. Negative correlations between BMI and ghrelin level (R = -0.7052; p < 0.05), WHR and adiponectin level (R = -0.6912; p < 0.05) and WHR and leptin level (R = -0.6728; p < 0.05) were observed in group B.

CONCLUSIONS

Insulin resistance and leptin may be important pathogenic factors in hypertensive patients with severe obesity. Indices of abdominal obesity (WC, WHR) correlate better than BMI with HOMA-IR, insulin, adiponectin and leptin serum levels in hypertensive obese patients.

Leptin in farm animals: where are we and where can we go?

Fat affects meat quality, value and production efficiency as well as providing energy reserves for pregnancy and lactation in farm livestock. Leptin, the adipocyte product of the obese (ob) gene, was quickly seen as a predictor of body fat content in animals approaching slaughter and an aid to assessing reproductive readiness in females. Its participation in inflammation and immune responses that help animals survive infection and trauma has clear additional relevance to meat and milk production. Furthermore, almost a decade of discoveries of nucleotide polymorphisms in the leptin and leptin receptor genes has suggested useful applications relating to feed intake regulation, the efficiency of feed use, the composition of growth, the timing of puberty, mammogenesis and mammary gland function and fertility in cattle, pigs and poultry. The current review attempts to summarise where research has taken us in each of these aspects and speculates on where future research might lead.

Comparative proteome analysis of 3T3-L1 adipocyte differentiation using iTRAQ-coupled 2D LC-MS/MS

Adipose tissue is critical in obesity and type II diabetes. Blocking of adipocyte differentiation is one of the anti-obesity strategies targeting on strong rise in fat storage and secretion of adipokine(s). However, the molecular basis of adipocyte differentiation and its regulation remains obscure. Therefore, we exposed 3T3-L1 cell line to appropriate hormonal inducers as adipocyte differentiation model. Using iTRAQ-coupled 2D LC-MS/MS, a successfully exploited high-throughput proteomic technology, we nearly quantitated 1,000 protein species and found 106 significantly altered proteins during adipocyte differentiation. The great majority of differentially expressed proteins were related to metabolism enzymes, structural molecules, and proteins involved in signal transduction. In addition to previously reported differentially expressed molecules, more than 20 altered proteins previously unknown to be involved with adipogenic process were firstly revealed (e.g., HEXB, DPP7, PTTG1IP, PRDX5, EPDR1, SPNB2, STEAP3, TPP1, etc.). The partially differential proteins were verified by Western blot and/or real-time PCR analysis. Furthermore, the association of PCX and VDAC2, two altered proteins, with adipocyte conversion was analyzed using siRNA method, and the results showed that they could contribute considerably to adipogenesis. In conclusion, our data provide valuable information for further understanding of adipogenesis.

Reduced cardiovascular risk following bariatric surgeries is related to a partial recovery from "adiposopathy"

BACKGROUND

Altered cytokine secretion from dysfunctional adipose tissue or "adiposopathy" is implicated in obesity related inflammation and may mediate reduced cardiovascular disease (CVD) risk in response to weight loss after bariatric surgery. We hypothesized that bariatric surgery reduces CVD risk by favorably altering the pro-inflammatory profile of adipose tissue as a result of weight loss.

METHODS

In this observational study with repeated measures, 142 patients underwent bariatric surgery of which 45 returned for follow-up at ∼6 months. At both time-points, lipid profiles and levels of plasma adiponectin, leptin, and TNF-α were obtained. Ratios of various adipokine parameters were related to pre- and post- surgical (gastric bypass vs. other restrictive bariatric procedures) lipid ratios.

RESULTS

Prior to surgery, circulating adiponectin and the adiponectin/TNF-α ratio was strongly associated with CVD risk characterized by levels of triglycerides, HDL, and the TC/HDL, LDL/HDL, and TG/HDL ratios (all P < 0.05). Following bariatric surgery, BMI was decreased by 22%, adiponectin was increased by 93%, and leptin decreased by 50% as compared to baseline (all P < 0.01). TNF-α levels increased by 120% (P < 0.01) following surgery. Post-surgical changes in adiponectin and the leptin/adiponectin ratio were strongly associated with incremental improvements in triglycerides, HDL, and TC/HDL, LDL/HDL and TG/HDL ratios (all P < 0.05). Roux-en-y gastric bypass surgery (RYGB) as compared to other bariatric procedures was associated with more robust improvements in BMI, HDL, and leptin/adiponectin ratio than other gastric restrictive procedures (P < 0.05).

CONCLUSIONS

Thus, bariatric surgery, especially RYGB, ameliorates CVD risk through a partial recovery from "adiposopathy", distinctively characterized by improved adiponectin and the leptin/adiponectin ratio.

Complement factor D in age-related macular degeneration

PURPOSE

To examine the role of complement factor D (CFD) in age-related macular degeneration (AMD) by analysis of genetic association, copy number variation, and plasma CFD concentrations.

METHODS

Single nucleotide polymorphisms (SNPs) in the CFD gene were genotyped and the results analyzed by binary logistic regression. CFD gene copy number was analyzed by gene copy number assay. Plasma CFD was measured by an enzyme-linked immunosorbent assay.

RESULTS

Genetic association was found between CFD gene SNP rs3826945 and AMD (odds ratio 1.44; P = 0.028) in a small discovery case-control series (462 cases and 325 controls) and replicated in a combined cohorts meta-analysis of 4765 cases and 2693 controls, with an odds ratio of 1.11 (P = 0.032), with the association almost confined to females. Copy number variation in the CFD gene was identified in 13 out of 640 samples examined but there was no difference in frequency between AMD cases (1.3%) and controls (2.7%). Plasma CFD concentration was measured in 751 AMD cases and 474 controls and found to be elevated in AMD cases (P = 0.00025). The odds ratio for those in the highest versus lowest quartile for plasma CFD was 1.81. The difference in plasma CFD was again almost confined to females.

CONCLUSIONS

CFD regulates activation of the alternative complement pathway, which is implicated in AMD pathogenesis. The authors found evidence for genetic association between a CFD gene SNP and AMD and a significant increase in plasma CFD concentration in AMD cases compared with controls, consistent with a role for CFD in AMD pathogenesis.

The evolution of the adipose tissue: a neglected enigma

The complexity of the anatomical distribution and functions of adipose tissue (AT) has been rarely analyzed in an evolutionary perspective. From yeast to man lipid droplets are stored mainly in the form of triglycerides in order to provide energy during periods when energy demands exceed caloric intake. This simple scenario is in agreement with the recent discovery of a highly conserved family of proteins for fat storage in both unicellular and multicellular organisms. However, the evolutionary history of organs such as the fat body in insects, playing a role in immunity and other functions besides energy storage and thermal insulation, and of differently distributed subtypes of AT in vertebrates is much less clear. These topics still await a systematic investigation using up-to-date technologies and approaches that would provide information useful for understanding the role of different AT subtypes in normal/physiological conditions or in metabolic pathologies of humans.

The crosstalks between adipokines and catecholamines

Adipocytes, which secrete a spectrum of adipokines, play an integral role in metabolism via communications with other endocrine cells. In the present work, we have studied the interplays between adipokines and catecholamines, using 3T3-L1 adipocytes and PC12 cells as the cell models and an integrative experimental platform. We demonstrate that all catecholamines inhibit vesicle trafficking and secretion of leptin and resistin through β-adrenergic receptors, while leptin and resistin enhance the vesicle trafficking and secretion of catecholamines through PKC, PKA, MAPK kinase and Ca(2+) dependent pathways. The crosstalks between adipokines and catecholamines were further corroborated by co-culturing 3T3-L1 adipocytes and PC12 cells. Our findings highlight the importance of adipo-adrenal axis in energy metabolism and the intricate interactions between metabolic hormones.

Adipokine concentrations in nonobese women: a study of reproductive aging, body mass index, and menstrual cycle effects

OBJECTIVE

To explore the influence of reproductive aging, body mass index (BMI), and the menstrual cycle on adiponectin (AD) and leptin concentrations.

DESIGN

Cross-sectional comparison in age- and BMI-matched nonobese volunteers with regular cycles (CO, n = 19) or in early postmenopause (EPM, n = 19), aged 40-52 years, and a young cycling group (CY, n = 21), aged 20-30 years.

MEASURES

Sex steroids, fasting AD, leptin, insulin, glucose, AD/leptin (A/L) ratio, and insulin resistance (IR) by homeostasis model assessment (HOMA-IR). In ovulatory women, AD, estradiol (E(2)), and progesterone were assessed weekly across the same menstrual cycle.

RESULTS

Insulin, glucose, HOMA-IR, A/L ratio, and leptin values were similar across the three study groups. AD differed, with the highest concentrations in the EPM group (CY: 13.0 +/- 0.9 microg/ml vs. CO: 14.0 +/- 1.1 microg/ml vs. EPM: 17.7 +/- 1.5 microg/ml; p = .05). Values among cycling women were similar. When the cycling groups were combined into a premenopausal (PRE) group and compared to EPM women by BMI (> or

CONCLUSION

Nonobese, midlife women experience minimal adverse effects from reproductive aging on insulin sensitivity and adipokine secretion. The menstrual cycle is not a key mediator of AD. Early menopause has differential, BMI-dependent effects on adipokine secretion.

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Key Words

• menopause
• menstrual cycle
• adipokines

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MESH Headings

• Adipokines/blood
• Adult
• Aging/blood
• Body Mass Index
• Female
• Humans
• Insulin Resistance
• Middle Aged
• Reproduction

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Grants

• P30 NR010677-03 NINR NIH HHS
• R01 AG015083-04 NIA NIH HHS
• P30 NR010677 NINR NIH HHS
• P30NR010677 NINR NIH HHS
• R01-AG15083-04 NIA NIH HHS
• 5-M01-00042 PHS HHS

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Affiliation(s)

Patricia A. Rouen McAuley School of Nursing, University of Detroit Mercy, 4001 W. McNichols Road., Detroit, MI 48221, , Phone: (313) 993-1739 Fax: (313) 993-1271
Jane L. Lukacs School of Nursing, University of Michigan, Ann Arbor, MI
Nancy E. Reame School of Nursing, Columbia University, New York, NY

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Ultra-sensitive detection of adipocytokines with CMOS-compatible silicon nanowire arrays

Perfectly aligned arrays of single-crystalline silicon nanowires were fabricated using top-down CMOS-compatible techniques. We demonstrate that these nanowire devices are able to detect adipocytokines secreted by adipose cells with femtomolar sensitivity, high specificity, wide detection range, and ability for parallel monitoring. The nanowire sensors also provide a novel tool to reveal the poorly understood signaling mechanisms of these newly recognized signaling molecules, as well as their relevance in common diseases such as obesity and diabetes.

Adiposopathy and bariatric surgery: is 'sick fat' a surgical disease?

OBJECTIVE

To review how bariatric surgery in obese patients may effectively treat adiposopathy (pathogenic adipose tissue or 'sick fat'), and to provide clinicians a rationale as to why bariatric surgery is a potential treatment option for overweight patients with type 2 diabetes, hypertension, and dyslipidaemia.

METHODS

A group of clinicians, researchers, and surgeons, all with a background in treating obesity and the adverse metabolic consequences of excessive body fat, reviewed the medical literature regarding the improvement in metabolic disease with bariatric surgery.

RESULTS

Bariatric surgery improves metabolic disease through multiple, likely interrelated mechanisms including: (i) initial acute fasting and diminished caloric intake inherent with many gastrointestinal surgical procedures; (ii) favourable alterations in gastrointestinal endocrine and immune responses, especially with bariatric surgeries that reroute nutrient gastrointestinal delivery such as gastric bypass procedures; and (iii) a decrease in adipose tissue mass. Regarding adipose tissue mass, during positive caloric balance, impaired adipogenesis (resulting in limitations in adipocyte number or size) and visceral adiposity are anatomic manifestations of pathogenic adipose tissue (adiposopathy). This may cause adverse adipose tissue endocrine and immune responses that lead to metabolic disease. A decrease in adipocyte size and decrease in visceral adiposity, as often occurs with bariatric surgery, may effectively improve adiposopathy, and thus effectively treat metabolic disease. It is the relationship between bariatric surgery and its effects upon pathogenic adipose tissue that is the focus of this discussion.

CONCLUSIONS

In selective obese patients with metabolic disease who are refractory to medical management, adiposopathy is a surgical disease.

Diet influences the content of bioactive peptides in goat milk

Leptin, insulin, ghrelin, and IGF-I are circulating peptide hormones concerned with energy homeostasis and the regulation of GH axis. They are present in human milk, and are thought to promote neonatal development. The aim of the present study was to detect these substances in goat milk and determine whether their levels can be modified by changing the macronutrient content of the lactating animals' diet. Sixteen Saanen goats in mid-lactation were divided into two balanced groups, one given a diet containing 17% starch (LS) and the other a diet of 33% starch (HS). Eighty days later, leptin, insulin, ghrelin, and IGF-I were determined by human radioimmunoassay kits in plasma before and after feeding, and in sonicated milk centrifuged to remove fat from morning and evening milking. The HS diet was associated with higher plasma and milk insulin and IGF-I, and plasma ghrelin. Leptin, insulin, and ghrelin in milk were two-three times higher than in plasma; milk IGF-I was only 5-20% of plasma level. Plasma insulin correlated positively with plasma IGF-I; morning milk IGFI and insulin correlated positively with morning plasma levels. These findings demonstrate that human immuno-activities of bioactive peptides are present in goat milk, and also that levels of insulin and IGF-I in milk can be altered by changing the macronutrient content of the diet. Further research is required to determine whether these substances can be transferred from the milk to suckling animals and humans, and whether they have biological activity in such animals.

The interface between obesity and periodontitis with emphasis on oxidative stress and inflammatory response

Obesity is characterized by the abnormal or excessive deposition of fat in the adipose tissue. Its consequences go far beyond adverse metabolic effects on health, causing an increase in oxidative stress that leads not only to endothelial dysfunction but also to negative effects in relation to periodontitis, because of the increase in proinflammatory cytokines. Thus, obesity appears to participate in the multifactorial phenomenon of causality of periodontitis through the increased production of reactive oxygen species. Within this context, this paper aims to highlight, by analysis and description of previous studies, the interface between obesity and periodontitis, with emphasis on oxidative stress and the inflammatory response.

Board-invited review: the biology and regulation of preadipocytes and adipocytes in meat animals

The quality and value of the carcass in domestic meat animals are reflected in its protein and fat content. Preadipocytes and adipocytes are important in establishing the overall fatness of a carcass, as well as being the main contributors to the marbling component needed for consumer preference of meat products. Although some fat accumulation is essential, any excess fat that is deposited into adipose depots other than the marbling fraction is energetically unfavorable and reduces efficiency of production. Hence, this review is focused on current knowledge about the biology and regulation of the important cells of adipose tissue: preadipocytes and adipocytes.

Effects of leptin on lipid metabolism and gene expression of differentiation-associated growth factors and transcription factors during differentiation and maturation of 3T3-L1 preadipocytes

The present study was designed to determine the effects of leptin on lipid metabolism and gene expression during differentiation and maturation of the 3T3-L1 murine preadipocyte. The preadipocytes were induced to differentiate in a growth medium containing 10% calf serum and a hormonal cocktail for 2 days. The cells were next allowed to maturate for 14 days in the growth medium supplemented with 10 microg/ml insulin or 500 ng/ml insulin-like growth factor (IGF)-I in the absence or presence of supplemented leptin. Leptin, at a dose of 5 to 500 ng/ml, had no effect on proliferation of undifferentiated 3T3-L1 cells. However, leptin suppressed the insulin- or IGF-I-stimulated lipid accumulation and enhanced the release of glycerol, a measure of lipolysis, in a dose-dependent manner during and after the maturation of the cell. Moreover, leptin at a dose of 50 ng/ml inhibited IGF-I gene expression during the entire differentiation and maturation and also peroxisome proliferator activated receptor (PPAR)-gamma expression during late maturation as monitored by semi-quantitative reverse transcription-polymerase chain reaction. However, leptin exerted no effect on the expression of transforming growth factor-beta, CCAT/enhancer binding protein-alpha and PPAR-delta. Taken together, results suggest the anti-lipogenic and lipolytic effects of leptin in differentiating and mature adipocytes may have been partly mediated by suppressing the expression of PPAR-gamma and IGF-I genes.

Reproductive endocrinology and clinical aspects of obesity in women

Obesity is a growing worldwide problem and is associated with a wide range of adverse effects on the female reproductive system. The endocrinological changes in obesity that may cause these adverse effects are complex and include changes in circulating adipokines and sex steroids as well as insulin resistance. Considerable evidence suggests an adverse effect of obesity on the risk of miscarriage and other maternal and fetal complications. Obese patients are also more prone to infertility. The most important single method to improve reproductive performance in obese women is weight loss that can be achieved with lifestyle changes and diet. Antiobesity drugs may also be used and, in severe cases, bariatric surgery.

Age-related changes in fatty acids from different adipose depots in rat and their association with adiposity and insulin

OBJECTIVE

We studied age-related changes in fatty acids (FAs) from serum and adipose tissue in rats by comparing different adipose regions and analyzed their relations to adiposity and insulin function.

METHODS

Female weaned rats were fed on a high-fat diet until 6, 14, and 20 mo of age (n = 12, n = 6, n = 10, respectively). Body weight, adiposity, serum insulin, serum glucose, and homeostatic model assessment index were measured. FA compositions from serum and interscapular brown, periovarian, mesenteric, and subcutaneous tissues were determined by gas chromatography.

RESULTS

Body weight and adiposity increased with age; visceral depots grew by hypertrophy, whereas subcutaneous depots grew by hyperplasia and in a higher ratio. Initially, the mesenteric tissue showed greater saturated and trans-FA contents, whereas brown tissue had higher polyunsaturated FA (PUFA) proportions. Aging resulted in a lower saturation degree in adipose tissue, attenuating earlier differences among depots. There was an elevation in omega-6 PUFAs with age, mainly because of C18:2omega-6, whereas omega-3 long-chain PUFAs, C20:5omega-3 and C22:6omega-3, tended to decrease in serum and adipose tissue. Adiposity was associated positively with monounsaturated FAs and inversely with PUFAs; insulin-related variables correlated negatively with serum omega-6 PUFA but positively with serum monounsaturated FAs and subcutaneous depot trans-FAs.

CONCLUSION

The mesenteric tissue showed the least favorable FA profile compared with the other depots, but differences among adipose regions diminished with age. In rats fed a high-fat diet, aging resulted in a lower saturation degree, with increased values in the cardiometabolic risk factor omega-6/omega-3 ratio in serum and adipose tissue.

Does breast size modify the association between mammographic density and breast cancer risk?

BACKGROUND

Both the absolute and the percent of mammographic density are strong and independent risk factors for breast cancer. Previously, we showed that the association between mammographic density and breast cancer risk tended to be weaker in African American than in White U.S. women. Because African American women have a larger breast size, we assessed whether the association between mammographic density and breast cancer was less apparent in large than in small breasts.

METHODS

We assessed mammographic density on mammograms from 348 African American and 507 White women, 479 breast cancer patients and 376 control subjects, from a case-control study conducted in Los Angeles County. We estimated odds ratios (OR) for breast cancer with increasing mammographic density, and the analyses were stratified by mammographic breast area.

RESULTS

Median breast size was 168.4 cm2 in African American women and 121.7 cm2 in White women (P for difference <0.001). For absolute density, adjusted ORs (95% confidence intervals) per increase of 10 cm2 were 1.32 (1.13-1.54), 1.14 (1.03-1.26), and 1.02 (0.98-1.07) in the first, second, and third tertiles of breast area, respectively (P for effect modification by breast area = 0.005). The results for percent density were similar although weaker; adjusted ORs per 10% increase (absolute value) in percent density were 1.22 (1.05-1.40), 1.22 (1.06-1.41), and 1.03 (0.90-1.18 P for effect modification by breast area = 0.34).

CONCLUSION

Our results indicate that the association between mammographic density and breast cancer may be weaker in women with larger breasts.

Pathogenic potential of adipose tissue and metabolic consequences of adipocyte hypertrophy and increased visceral adiposity

When caloric intake exceeds caloric expenditure, the positive caloric balance and storage of energy in adipose tissue often causes adipocyte hypertrophy and visceral adipose tissue accumulation. These pathogenic anatomic abnormalities may incite metabolic and immune responses that promote Type 2 diabetes mellitus, hypertension and dyslipidemia. These are the most common metabolic diseases managed by clinicians and are all major cardiovascular disease risk factors. 'Disease' is traditionally characterized as anatomic and physiologic abnormalities of an organ or organ system that contributes to adverse health consequences. Using this definition, pathogenic adipose tissue is no less a disease than diseases of other body organs. This review describes the consequences of pathogenic fat cell hypertrophy and visceral adiposity, emphasizing the mechanistic contributions of genetic and environmental predispositions, adipogenesis, fat storage, free fatty acid metabolism, adipocyte factors and inflammation. Appreciating the full pathogenic potential of adipose tissue requires an integrated perspective, recognizing the importance of 'cross-talk' and interactions between adipose tissue and other body systems. Thus, the adverse metabolic consequences that accompany fat cell hypertrophy and visceral adiposity are best viewed as a pathologic partnership between the pathogenic potential adipose tissue and the inherited or acquired limitations and/or impairments of other body organs. A better understanding of the physiological and pathological interplay of pathogenic adipose tissue with other organs and organ systems may assist in developing better strategies in treating metabolic disease and reducing cardiovascular disease risk.

PPARgamma and GLUT-4 expression as developmental regulators/markers for preadipocyte differentiation into an adipocyte

In this document, we have integrated knowledge about two major cellular markers found in cells of the adipocyte lineage (an adipogenic marker and a metabolic marker). This review provides information as to how differentiation of a cell (such as an adipofibroblast, fibroblast or preadipocyte) to become a viable (and new) adipocyte is under different regulation than that experienced by an immature adipocyte that is just beginning to accumulate lipid. The differentiation, prior to lipid-filling, involves PPARgamma. Subsequently, lipid-filling of the adipocyte relies on a late subset of genes and, depending on depot specificity, involves GLUT-4 or any number of other metabolic markers.

Calcitriol and calcium regulate cytokine production and adipocyte-macrophage cross-talk

OBJECTIVE

The objective of this study was to investigate the effects of calcitriol on adipocyte and macrophage cytokine expression as well as release and on adipocyte-macrophage cross-talk in local modulation of inflammation.

RESEARCH PROCEDURES AND RESULTS

We investigated calcitriol modulation of the expression of macrophage inhibitory factor (MIF) and macrophage surface-specific protein CD14, two key factors in regulating macrophage function and survival, in differentiated human adipocytes. Calcitriol significantly increased MIF and CD14 expression by 59% and 33%, respectively, while calcium-channel antagonism with nifedipine completely reversed these effects, indicating that calcitriol stimulates MIF and CD14 expression via a calcium-dependent mechanism. Similar results were also found in cultured 3T3-L1 adipocytes; in addition, calcitriol also up-regulated macrophage colony-stimulating factor, macrophage inflammatory protein, interleukin-6 (IL-6) as well as monocyte chemoattractant protein-1 expression in 3T3-L1 adipocytes and stimulated tumor necrosis factor as well as IL-6 expression in RAW 264 macrophages. These effects were blocked by either a calcium-channel antagonist (nifedipine) or a mitochondrial uncoupler (dinitrophenol). Moreover, co-culture of 3T3-L1 adipocytes with RAW 264 macrophages significantly increased the expression and production of multiple inflammatory cytokines in response to calcitriol in both cell types.

CONCLUSIONS

These data demonstrate that calcitriol regulates local inflammation via modulating the interaction between adipocytes and macrophages as well as regulating inflammatory cytokine production in each cell type via calcium-dependent and mitochondrial uncoupling-dependent mechanisms. These data provide further mechanistic explanation for our recent observations that suppression of calcitriol by dietary calcium reduces inflammatory cytokine expression and oxidative stress in adipose tissue.

Engineering adipose-like tissue in vitro and in vivo utilizing human bone marrow and adipose-derived mesenchymal stem cells with silk fibroin 3D scaffolds

Biomaterials derived from silk fibroin prepared by aqueous (AB) and organic (HFIP) solvent-based processes, along with collagen (COL) and poly-lactic acid (PLA)-based scaffolds were studied in vitro and in vivo for their utility in adipose tissue engineering strategies. For in vitro studies, human bone marrow and adipose-derived mesenchymal stem cells (hMSCs and hASCs) were seeded on the various biomaterials and cultured for 21 days in the presence of adipogenic stimulants (AD) or maintained as noninduced controls. Alamar Blue analysis revealed each biomaterial supported initial attachment of hMSCs and hASCs to similar levels for all matrices except COL in which higher levels were observed. hASCs and hMSCs cultured on all biomaterials in the presence of AD showed significant upregulation of adipogenic mRNA transcript levels (LPL, GLUT4, FABP4, PPARgamma, adipsin, ACS) to similar extents when compared to noninduced controls. Similarly Oil-Red O analysis of hASC or hMSC-seeded scaffolds displayed substantial amounts of lipid accumulating adipocytes following cultivation with AD. The data revealed AB and HFIP scaffolds supported similar extents of lipid accumulating cells while PLA and COL scaffolds qualitatively displayed lower and higher extents by comparison, respectively. Following a 4-week implantation period in a rat muscle pouch defect model, both AB and HFIP scaffolds supported in vivo adipogenesis either alone or seeded with hASCs or hMSCs as assessed by Oil-Red O analysis, however the presence of exogenous cell sources substantially increased the extent and frequency of adipogenesis observed. In contrast, COL and PLA scaffolds underwent rapid scaffold degradation and were irretrievable following the implantation period. The results suggest that macroporous 3D AB and HFIP silk fibroin scaffolds offer an important platform for cell-based adipose tissue engineering applications, and in particular, provide longer-term structural integrity to promote the maintenance of soft tissue in vivo.

Adiponectin inhibits superoxide generation by human neutrophils

Adiponectin (Ad), a member of the adipocytokine family, has been reported to possess antiinflammatory properties. We investigated the effects of full-length human Ad (hAd) on phorbol 12-myristate 13-acetate (PMA)-induced O2-* generation by human neutrophils. hAd, even at the lowest tested concentration of 0.001 microg/ml, after 30-min pretreatment of cells, significantly inhibited O2-* generation by neutrophils stimulated with PMA (100 nM). However, no relation between the dose of hAd and extent of inhibition of PMA-induced O2-* generation was observed with increasing the concentration of hAd up to 1 microg/ml. hAd also significantly inhibited neutrophil O2-* generation stimulated by N-formyl-methionyl-leucyl-phenylalanine (100 microM) and diacylglycerol (500 nM), as well as the PMA-induced neutrophil nitroblue tetrazolium reduction and H2O2 formation. Pretreatment of neutrophils with pronase-digested hAd failed to inhibit the PMA-induced O2-* generation. For the first time, this study revealed that Ad inhibited O2-* generation by neutrophils, possibly through regulation of NADPH oxidase.

Presence of functional TLR2 and TLR4 on human adipocytes

In addition to the well-known role of adipose tissue in energy metabolism, it has recently been demonstrated that this tissue can secrete a large array of molecules, including inflammatory cytokines. Furthermore, recent studies suggest that adipose cells can behave as immune cells. Therefore, the aim of this study was to determine the presence of the two most prominent 'pattern recognition receptors' for bacterial and fungal cell wall components, TLR2 and TLR4 on human adipose cells, as well as to assess their functionality. We demonstrated that TLR2 and TLR4 were expressed at relatively high levels (compared to a monocyte cell line) on the surface of human adipose cells. Stimulation of human adipocytes with lipopolysaccharide (LPS), or with lipoteichoic acid (LTA), two specific ligands of TLR4 and TLR2, respectively, induced a strong increase in TNFalpha production. The specificity of the response was demonstrated by the use of anti-TLR4 and anti-TLR2 blocking antibodies, which were able to decrease LPS- or LTA-induced TNFalpha secretion. Thus, it is clear that these receptors are functional in human adipocytes. This study adds weight to the argument that human fat tissue plays a potential role in innate immunity.