Health related quality of life associated with extreme obesity in adolescents - results from the baseline evaluation of the YES-study.

BACKGROUND: Obesity can significantly reduce health-related quality of life (HRQoL) and may lead to numerous health problems even in youths. This study aimed to investigate whether HRQoL varies among youths with obesity depending on grade of obesity and other factors. METHODS: For the Youths with Extreme obesity Study (YES) (2012-2014), a prospective multicenter cohort study, a baseline sample of 431 obese and extremely obese adolescents and young adults (age 14 to 24 years, BMI ≥30 kg/m2) was recruited at four German university medical centers and one job center. Obesity grade groups (OGG) were defined according to BMI (OGG I: 30-34.9 kg/m2, OGG II: 35-39.9 kg/m2, OGG III (extreme obesity): ≥40 kg/m2). HRQoL was measured with the Euroqol-5D-3 L (EQ-5D-3 L), DISABKIDS chronic generic (DCGM-31) and the KINDLR obesity module. Differences between OGGs were assessed with logistic and linear regression models, adjusting for age, sex, and study center in the base model. In a second regression analysis, we included other characteristics to identify possible determinants of HRQoL. RESULTS: Three hundred fifty-two adolescents (mean age: 16.6 (±2.4), mean BMI: 39.1 (±7.5) kg/ m2) with available HRQoL data were analysed. HRQoL of youths in all OGGs was markedly lower than reference values of non-obese adolescents. Adjusting for age and sex, HRQoL of youths in OGG III significantly impaired compared to OGG I. Youths in OGG III were 2.15 times more likely to report problems with mobility in the EQ-5D-3 L than youths in OGG I. A mean difference of 9.7 and 6.6 points between OGG III and I were found for DCGM-31 and KINDL respectively and 5.1 points between OGG II and I for DCGM-31. Including further variables into the regression models, showed that HRQoL measured by DCGM-31 was significantly different between OGGs. Otherwise, female sex and having more than 4 h of daily screen time were also associated with lower HRQoL measured by DCGM-31 and KINDL. CONCLUSION: HRQoL of adolescents with obesity is reduced, but HRQoL of adolescents with extreme obesity is particularly affected. Larger and longitudinal studies are necessary to understand the relation of extreme obesity and HRQoL, and the impact of other lifestyle or socioeconomic factors. TRIAL REGISTRATION: Clinicaltrials.gov NCT01625325; German Clinical Trials Register (DRKS) DRKS00004172.

[Recognize rare diseases by the adipose tissue : Lipodystrophy-actually simple but nevertheless often overlooked]. / Seltene Erkrankungen am Fettgewebe erkennen : Lipodystrophie ­ eigentlich einfach und dennoch oft übersehen.

Lipodystrophy (LD) syndromes are a group of rare and heterogeneous diseases characterized by a congenital deficiency or acquired loss of adipose tissue. Due to the resulting disorder of metabolism, sometimes severe sequelae can develop, such as hypertriglyceridemia, marked insulin resistance and early manifestation of type 2 diabetes, recurrent pancreatitis, fatty liver disease and liver fibrosis. Lipodystrophies are clinically recognizable due to the complete lack of subcutaneous adipose tissue or a conspicuous pattern of the distribution of body fat. Acanthosis nigricans in slimly built persons, a high fasting triglyceride level and elevated concentrations of liver enzymes as well as a positive history of pancreatitis can be indications of LD.

Prevalence and phenotypic characterization of MC4R variants in a large pediatric cohort.

OBJECTIVE: We aimed to determine the prevalence of melanocortin-4 receptor (MC4R) variants in a large German cohort of children with obesity in a pediatric outpatient clinic and to ascertain whether there is a specific phenotype associated with loss-of-function variants as previously reported. STUDY DESIGN: Eight hundred and ninety-nine patients from our pediatric obesity clinic were screened for MC4R variants by DNA sequencing after PCR amplification. Retrospective statistical analysis of anthropometric and metabolic characteristics was performed, comparing patients with and without MC4R variants across the entire cohort (n=586) as well as in case-control analysis using patients with common sequence MC4R individually matched for age, sex and body mass index standard deviation score (SDS) (n=11 case-control pairs). RESULTS: We identified heterozygous variants within the coding region of the MC4R gene in n=22 (2.45%) patients. Fourteen (1.56%) had a variant that impaired receptor function. One new frameshift (p.F152Sfs), an yet unpublished nonsense mutation (p.Q156X) and one nonsynonymous variation (p.V65E) described in the Mouse Genome Database were detected. Across the whole cohort, at all ages, mean height SDS in subjects with impaired receptor function was higher than in patients with common sequence MC4R. In matched individuals, this trend persisted (8 of the 11 pairs) within the case-control setting. No differences were found regarding metabolic characteristics. CONCLUSIONS: The observed prevalence of mutations causing impaired receptor function in this large cohort is comparable to other pediatric cohorts. MC4R deficiency tends to lead to a taller stature, confirming previous clinical reports. The association of MC4R mutations with a distinct phenotype concerning metabolic characteristics remains questionable.

New approach shows no association between maternal milk fatty acid composition and childhood wheeze or asthma.

BACKGROUND: Previous observational studies have implied breastmilk fatty acid composition may play a role in the development of atopic eczema or atopic sensitization in breastfed infants and toddlers. However, studies investigating associations with wheeze and asthma in later childhood are scarce and did not account for inherent correlation of compositional data. Our aim was to explore the association of maternal milk fatty acid composition with childhood wheezing phenotypes and asthma up to age 13 years using a new statistical approach. METHODS: Breastmilk was collected 6 weeks and 6 months postdelivery in the Ulm Birth Cohort Study (n=720 and n=454, respectively). Concentrations of 28 fatty acids were measured by high-resolution capillary gas-liquid chromatography. To control for constant-sum constraint, concentration data were transformed using the centered log ratio method. Compositional biplots and correlation matrices were used to group centered log ratio transformed fatty acids. Adjusted risk ratios with parent-reported wheezing phenotypes and doctor-diagnosed asthma were computed using a modified Poisson regression. RESULTS: We observed no straightforward evidence of associations between overall breastmilk fatty acid composition and specific wheeze phenotypes or doctor-diagnosed asthma. CONCLUSION: Using appropriate statistical methodology, we report null associations. These findings may partly be attributable to several cohort-specific factors associated with breastfeeding and breastmilk collection. Further studies could improve on ours by analyzing samples of breastmilk and formula and by including all children for whom these are exclusively or together the major source of fatty acids in the first months of life.

Anti-inflammatory properties of bone morphogenetic protein 4 in human adipocytes.

BACKGROUND: Obesity is characterized by increased adipocyte number and size as well as white adipose tissue (WAT) inflammation, which is fundamental for the development of insulin resistance and type-2 diabetes. These processes, regulated by various endocrine, paracrine and autocrine factors, are extensively studied with the hope to interfere and to inhibit weight gain and related complications in obese patients. Recent data suggest an important role of bone morphogenic protein 4 (BMP4) in the regulation of adipogenesis and development of obesity. BMP4 is a growth factor of the transforming growth factor-ß superfamily. Initially, BMPs were identified as inducers of ectopic bone formation. It is now apparent, however, that these proteins have different pleiotropic developmental actions and including playing a role in white adipogenesis. METHODS AND RESULTS: Here, we demonstrate that the expression of BMP4 in human WAT is negatively correlated to body mass index and to the expression of pro-inflammatory cytokines. In vitro, BMP4 expression in cultured human adipocytes is upregulated after induction of differentiation. Cells treated with exogenous BMP4 increased peroxisome proliferator-activated receptor γ (PPARγ) expression and significantly reduced the expression of pro-inflammatory cytokines including tumor necrosis factor α (TNF-α) and monocyte chemoattractant protein 1. TNF-α treatment of fully differentiated adipocytes resulted in downregulation of the expression of adipogenic genes and elevated expression of pro-inflammatory cytokines. Exogenous BMP4 addition significantly reduced the negative effect of TNF-α on the expression profile of adipocytes. Finally, treatment of human adipocytes with exogenous BMP4 reduced the adipocytes' chemoattractant potential and the migration of monocytes toward adipocyte-conditioned medium. CONCLUSIONS: These results indicate that BMP4 is an important anti-inflammatory molecule, which may act through PPARγ and reduces TNF-α-mediated pro-inflammatory cytokine production in human adipocytes. Through its anti-inflammatory potential, BMP4 may serve as a protective factor for inflammation-related diseases such as insulin-tolerance or type-2 diabetes.

Insulin/glucose induces natriuretic peptide clearance receptor in human adipocytes: a metabolic link with the cardiac natriuretic pathway.

Cardiac natriuretic peptides (NP) are involved in cardiorenal regulation and in lipolysis. The NP activity is largely dependent on the ratio between the signaling receptor NPRA and the clearance receptor NPRC. Lipolysis increases when NPRC is reduced by starving or very-low-calorie diet. On the contrary, insulin is an antilipolytic hormone that increases sodium retention, suggesting a possible functional link with NP. We examined the insulin-mediated regulation of NP receptors in differentiated human adipocytes and tested the association of NP receptor expression in visceral adipose tissue (VAT) with metabolic profiles of patients undergoing renal surgery. Differentiated human adipocytes from VAT and Simpson-Golabi-Behmel Syndrome (SGBS) adipocyte cell line were treated with insulin in the presence of high-glucose or low-glucose media to study NP receptors and insulin/glucose-regulated pathways. Fasting blood samples and VAT samples were taken from patients on the day of renal surgery. We observed a potent insulin-mediated and glucose-dependent upregulation of NPRC, through the phosphatidylinositol 3-kinase pathway, associated with lower lipolysis in differentiated adipocytes. No effect was observed on NPRA. Low-glucose medium, used to simulate in vivo starving conditions, hampered the insulin effect on NPRC through modulation of insulin/glucose-regulated pathways, allowing atrial natriuretic peptide to induce lipolysis and thermogenic genes. An expression ratio in favor of NPRC in adipose tissue was associated with higher fasting insulinemia, HOMA-IR, and atherogenic lipid levels. Insulin/glucose-dependent NPRC induction in adipocytes might be a key factor linking hyperinsulinemia, metabolic syndrome, and higher blood pressure by reducing NP effects on adipocytes.

[Current Guidelines to Prevent Obesity in Childhood and Adolescence]. / Aktuelle Empfehlungen zur Prävention der Adipositas im Kindes- und Jugendalter.

BACKGROUND: Current guidelines for the prevention of obesity in childhood and adolescence are presented. METHODS: A literature search was performed in Medline via PubMed, and appropriate studies were analysed. RESULTS: Programs to prevent childhood obesity were to date mainly school-based. Effects were limited to date. Analyses tailored to different age groups show that prevention programs have the best effects in younger children (< 12 years). Evidence based recommendations for preschool- and early school age imply the need for interventions addressing parents and teachers alike. During adolescence, school-based interventions were most effective when adolescents were directly addressed. To date, obesity prevention programs have mainly focused on behavior oriented prevention. Recommendations for condition oriented prevention have been suggested by the German Alliance of Non-communicable Diseases and include one hour of physical activity at school, promotion of healthy food choices by taxing unhealthy foods, mandatory quality standards for meals at kindergarten and schools as well as a ban on unhealthy food advertisement addressing children. CONCLUSION: Behavior oriented prevention programs showed hardly any or only limited effects in the long term. Certain risk groups for the development of obesity are not reached effectively by available programs. Due to the heterogeneity of available studies, universally valid conclusions cannot be drawn. The combination with condition oriented prevention, which has to counteract on an obesogenic environment, is crucial for sustainable success of future obesity prevention programs.

Ethnicity and cardiovascular risk factors: evaluation of 40,921 normal-weight, overweight or obese children and adolescents living in Central Europe.

BACKGROUND AND AIMS: Cardiovascular disease (CVD) is a major global health problem and the leading cause of death in Europe. Risk factors such as obesity and hypertension that accelerate the development of CVD begin in childhood. Ethnicity is a known risk factor for CVD in adults. The aim of this study is to explore differences in the prevalence of hypertension and dyslipidemia among overweight/obese and normal-weight children/adolescents of three different ethnic origins living in Central Europe. METHODS AND PROCEDURES: Prevalence of hypertension and dyslipidemia was calculated among obese/overweight children/adolescents (n = 25,986; mean age 12.7 ± 3.0 years; range: 0-18 years; 46% males) documented in the German-Austrian-Swiss APV (Prospective Documentation of Overweight Children and Adolescents) registry and among normal-weight subjects (n = 14,935; mean age: 8.8 ± 5.1 years; range 0-18 years; 51% males) from the population-based cross-sectional German Health Interview and Examination Survey for Children and Adolescents (KiGGS) study. In both cohorts, subjects were categorized into three ethnic groups (Central European: Germany, Austria, Switzerland; Southeastern European: Turkish; Southern European: Spain, Portugal, Italy, Greece, Cyprus, Malta) based on the country of birth of both parents. Regression models were used to examine ethnic differences after adjustment for age and gender and body mass index (BMI) category. RESULTS: Age-, gender- and BMI category-adjusted prevalence of hypertension were 38% and 39% for the ethnic minority groups, compared with 35% among German/Austrian/Swiss counterparts. Turkish ethnicity was significantly associated with hypertension (odds ratio (OR) 1.14; 95% confidence interval: 1.02-1.27; P = 0.0446). No significant ethnic differences were found in lipid levels. Prevalence of hypertension found among normal-weight subjects (Central European vs Southeastern vs Southern European: 6.8% vs 6.3% vs 7.2%) did not differ significantly. CONCLUSIONS: Turkish obese/overweight children/adolescents showed a significantly higher prevalence of hypertension relative to their peers of Central European descent. No significant ethnic difference in the prevalence of hypertension was found among normal-weight children/adolescents. The high prevalence of hypertension among Turkish obese/overweight children/adolescents indicates the need for greater preventive and therapeutic efforts to reduce cardiovascular risk factors among vulnerable populations.

Calcium-dependent release of adipocyte fatty acid binding protein from human adipocytes.

BACKGROUND: Fatty acid binding protein 4 (FABP4) is a predominantly cytosolic protein of the adipocytes, but also abundantly present in human plasma; its plasma concentrations were linked to obesity and metabolic syndrome. Recent studies have suggested a direct extracellular effect of FABP4 in the regulation of glucose metabolism and heart function independently of its effect as a carrier protein. Interestingly, FABP4 has no secretory signal sequence; hence, the mechanisms how FABP4 is released from adipocytes are unclear. METHODS AND RESULTS: In this study we investigated the mechanisms for FABP4 secretion from human adipocytes by using isolated primary pre-adipocytes (PAs) and the human adipocyte cell strain Simpson-Golabi-Behmel syndrome. In undifferentiated PAs, FABP4 expression was barely detectable and increased continuously during differentiation. The increase in FABP4 mRNA expression was accompanied by high levels of FABP4 secretion. In differentiated human adipocytes, FABP4 secretion was not abolished by blocking the Golgi-dependent secretory pathway in vitro, supporting a non-classical secretion mechanism for FABP4. However, raising intracellular Ca(2+) levels enhanced FABP4 secretion in a concentration-dependent manner. CONCLUSION: This study shows that FABP4 is actively released from human adipocytes in vitro via a non-classical, calcium-dependent mechanism.

Bariatric surgery in adolescents and young adults--safety and effectiveness in a cohort of 345 patients.

OBJECTIVE: To examine the safety and effectiveness of adolescent bariatric surgery and to improve treatment recommendations for this age group. DESIGN: Prospective longitudinal registry. Since January 2005, patients undergoing bariatric surgery in Germany are enlisted in an online registry called 'study for quality assurance in obesity surgeries'. SUBJECTS: Adolescents and young adults up to the age of 21 years, operated from January 2005 to December 2010. MEASUREMENTS: Weight, BMI, comorbidities, complication rates. RESULTS: N=345 primary procedures were recorded by 58 hospitals. N=51 patients were under the age of 18 years. Follow-up information was available for 48% (n=167) of patients, with an average observation period of 544±412 days (median: 388 days). The most common surgical techniques were gastric banding (n=118, 34.2%), gastric bypass (n=116, 33.6%) and sleeve gastrectomy (n=78, 22.6%). Short-term complications (intra-operative; general postoperative; specific postoperative) were slightly lower for gastric banding (0.8%; 2.5%; 0.8%) than for gastric bypass (2.6%; 5.2%; 1.7%) or sleeve gastrectomy (0%; 9.0%; 7.7%). In accordance with published findings, weight and BMI reduction were lower for gastric banding (-28 kg; -9.5 kg m(-2)) compared to gastric bypass (-50 kg; -16.4 kg m(-2)) P< 0.001 or sleeve gastrectomy (-46 kg; -15.4 kg m(-2)) P< 0.001. Outcomes did not differ between the <18 and ≥18-year-old patients. CONCLUSION: Like in adults, bariatric surgery has low short-term complication rates and results in sustained weight loss in adolescents. However, the missing long-term observations prohibit a final conclusion about lasting effectiveness and safety. Clinical trials with structured follow-up programs and mechanisms to ascertain patient adherences are needed.

Evidence of inappropriate cardiovascular risk assessment in middle-age women based on recommended cut-points for waist circumference.

BACKGROUND AND AIMS: Diverse waist circumference thresholds for assessment of metabolic and cardiovascular risk in Caucasians are recommended by different health professional organizations. We aimed to determine optimal sex-specific thresholds for anthropometric measures showing the strongest association with cardiovascular risk factors in a cohort of middle-aged Germans. METHODS AND RESULTS: Statistical analyses are based on data from 426 mothers and 267 fathers of participants of the Ulm Birth Cohort Study undergoing a clinical follow-up examination in 2008 (median age 41 years) using logistic regression analyses. The prevalence of many cardiometabolic risk factors was significantly higher in men than in women; hypertension: 45%/17% (p < 0.0001), apolipoprotein ratio B/A1 > 0.72: 35%/9% (<0.0001), hyperglycemia: 11%/14% (p = 0.3), which is in contrast to the predicted cardiovascular risk of 52%/70% and 24%/36% based on thresholds for waist circumference proposed by International Diabetes Federation and American Heart Association, respectively. We determined optimal thresholds for waist circumference between 90 and 95 cm for men and women. Using a threshold of 92 cm the prevalence of abdominal obesity was 59% in men and 24% in women, which was in agreement with the higher prevalence of overweight and obesity in men than in women (Body Mass Index (BMI) > 25: 64%/35%). The prediction of cardiometabolic risk factors by waist circumference and waist-to-height ratio did not outperform the prediction by BMI. In contrast to BMI, waist circumference was correlated with body height independent of sex. CONCLUSION: Currently proposed thresholds for waist circumference spuriously overestimate the cardiovascular risk in women, but not in men in a German population.

Influence of Tyrphostin AG490 on the expression of diabetes-associated markers in human adipocytes.

Tyrosine kinase inhibitors (TKi) hold promise as a treatment for a variety of disorders ranging from those in oncology to diseases thought as immune mediated. Tyrphostin AG490 is a potent Jak-Stat TKi shown effective in the prevention of allograft transplant rejection, experimental autoimmune disease, as well as the treatment of cancer. However, given its ability to modulate this important but pleiotropic intracellular pathway, we thought that it is important to examine its effects on glucose metabolism and expression of major transcription factors and adipokines associated with insulin insensitivity and diabetes. We investigated the metabolic effects of AG490 on glucose levels in vivo using an animal model of diabetes, nonobese diabetic (NOD) mice, and transcription factor expression through assessment of human adipocytes. AG490 treatment of young nondiabetic NOD mice significantly reduced blood glucose levels (p = 0.002). In vitro, treatment of adipocytes with rosiglitazone, an insulin sensitizer that binds to peroxisome proliferator-activated receptor (PPAR) receptors and increases the adipocyte response to insulin, significantly increased the expression of the antidiabetic adipokine adiponectin. Importantly, the combination of rosiglitazone plus Tyrphostin AG490 further increased this effect and was specifically associated with significant upregulation of C-enhanced binding protein (C/EBP) (p < 0.0001). In terms of the mechanism underlying this action, regulatory regions of the PPARγ, ADIPOQ, and C/EBP contain the Stat5 DNA-binding sequences and were demonstrated, by gel shift experiments in vitro. These data suggest that blocking Jak-Stat signaling with AG490 reduces blood glucose levels and modulates the expression of transcription factors previously associated with diabetes, thereby supporting its potential as a therapy for this disease.

[Hormonal alterations in obese children and adolescents]. / Hormonelle Folgestörungen bei Adipositas im Kindes- und Jugendalter.

There are a number of rare endocrine causes of obesity including defined genetic syndromes. However, there are frequent alterations in endocrine functions in obesity, which are characteristic of the obese state, including disorders of insulin secretion and function, alterations in the function of the growth hormone-IGF-1 axis, the hypothalamic-pituitary-thyroid axis, the hypothalamic-pituitary-adrenal axis, and pubertal development. The characteristic endocrine alterations in obesity may have an influence on energy metabolism and energy storage. Alterations in glucocorticoid production and metabolism and the impaired growth hormone production for example show that these secondary endocrine changes may facilitate further increase in weight. Notwithstanding this, all described endocrine changes are completely or partially reversible under calorie restriction and weight loss.

Transcriptomic analysis of Simpson Golabi Behmel syndrome cells during differentiation exhibit BAT-like function.

High-throughput RNA sequencing of human Simpson-Golabi-Behmel syndrome cells (SGBS) was performed during the time-course of adipogenic differentiation at day 4 (D04), 6 (D06), 8 (D08), and 10 (D10) to characterize transcriptomic changes and to identify key patterns involved in adipogenesis and browning. In the comparisons, 932 and 384 overlapping transcripts were consistently up- and down-regulated, respectively. Combining the results of protein-protein interaction network analysis MCODE and CytoHubba, 55 up-regulated hub genes from four clusters and 9 down-regulated genes were identified. The up-regulated hub genes were mainly enriched in brown adipocyte differentiation, extracellular matrix organization, and valine, leucine, and isoleucine degradation. The enrichment of downregulated hub genes was related to NRF2 signalling and glutathione metabolism, indicating that oxidative stress also plays a role. Analysis of overlapping down-regulated genes, targets of transcription factors, revealed enrichment in the IL-18 signalling pathway, which is involved in browning process and extracellular matrix organization via actomyosin mechanics and integrin-extracellular matrix interactions. Finally, the comparison transcriptomic analysis with the gene signature reported by BATLAS and PROFAT web-based tools showed an increased percentage of the brown phenotype, confirming that differentiated SGBS cells at D06, D08, and D10 gradually acquire BAT-like function.

Hypoxia-driven metabolic reprogramming of adipocytes fuels cancer cell proliferation.

Objective: Obesity increases the risk of certain cancers, especially tumours that reside close to adipose tissue (breast and ovarian metastasis in the omentum). The obesogenic and tumour micro-environment share a common pathogenic feature, oxygen deprivation (hypoxia). Here we test how hypoxia changes the metabolome of adipocytes to assist cancer cell growth. Methods: Human and mouse breast and ovarian cancer cell lines were co-cultured with human and mouse adipocytes respectively under normoxia or hypoxia. Proliferation and lipid uptake in cancer cells were measured by commercial assays. Metabolite changes under normoxia or hypoxia were measured in the media of human adipocytes by targeted LC/MS. Results: Hypoxic cancer-conditioned media increased lipolysis in both human and mouse adipocytes. This led to increased transfer of lipids to cancer cells and consequent increased proliferation under hypoxia. These effects were dependent on HIF1α expression in adipocytes, as mouse adipocytes lacking HIF1α showed blunted responses under hypoxic conditions. Targeted metabolomics of the human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes media revealed that culture with hypoxic-conditioned media from non-malignant mammary epithelial cells (MCF10A) can alter the adipocyte metabolome and drive proliferation of the non-malignant cells. Conclusion: Here, we show that hypoxia in the adipose-tumour microenvironment is the driving force of the lipid uptake in both mammary and ovarian cancer cells. Hypoxia can modify the adipocyte metabolome towards accelerated lipolysis, glucose deprivation and reduced ketosis. These metabolic shifts in adipocytes could assist both mammary epithelial and cancer cells to bypass the inhibitory effects of hypoxia on proliferation and thrive.

Human growth hormone receptor (GHR) expression in obesity: II. Regulation of the human GHR gene by obesity-related factors.

BACKGROUND AND METHODS: In our previous analyses, we found significantly lower levels of growth hormone receptor (GHR) mRNA in adipose tissues of obese than in those of lean individuals, suggesting that idiopathic obesity involves GH resistance due to decreased GHR availability. To understand the mechanism(s) behind this downregulation, we performed an in silico analysis of the three most relevant GHR gene promoters, which revealed putative response elements (REs) for a number of obesity adipose-associated factors, including tumor necrosis factor-alpha (TNFα), hypoxia-inducible factor-1-alpha (HIF-1α) and glucocorticoids. We then characterized the dose-dependent effects of these factors on GHR expression in HEK293 cells and in mature human SGBS (Simpson-Golabi-Behmel syndrome) adipocytes using quantitative reverse transcriptase-PCR and assessed the function of their putative REs by luciferase-reporter assays, site-directed mutagenesis and chromatin immunoprecipitation (ChIP) assays. RESULTS: TNFα treatments significantly reduced GHR mRNA levels and GHR promoter activities at doses ≥ 10 ng ml(-1) in both cell lines. Transient overexpression of HIF-1α or exposure to the hypoxia mimetic CoCl(2) significantly increased GHR mRNA levels and promoter activities. Dexamethasone had biphasic effects: there was a significant increase in GHR mRNA levels at 10(-10) M and in promoter activities at 10(-10) and 10(-8) M, whereas a significant decrease in both mRNA levels and promoter activities occurred at 10(-6) M. Site-directed mutagenesis of the putative nuclear factor-κB, HIF-1α and glucocorticoid REs resulted in the loss of these effects, whereas ChIP analysis confirmed specific transcription factor-promoter interactions. CONCLUSIONS: Our results suggest that the increased activity of TNFα, HIF-1α and glucocorticoids in obese adipose tissues could alter GHR gene transcription through specific REs and that TNFα may be involved in the development of GH resistance.

LIGHT (TNFSF14) inhibits adipose differentiation without affecting adipocyte metabolism.

OBJECTIVE: The member of the tumor necrosis factor family LIGHT (lymphotoxin-like inducible protein that competes with glycoprotein D for herpesvirus entry on T cells; TNFSF14 (tumor necrosis factor super family protein 14) is primarily expressed in lymphocytes, in which it induces the expression of pro-inflammatory cytokines and alterations of lipid homeostasis. Recently, the protein was shown to be upregulated in obesity and to induce cytokine secretion from adipocytes. RESEARCH METHODS AND PROCEDURES: Using an automated complementary DNA (cDNA) screen, LIGHT was identified to inhibit adipose differentiation. As cellular models for adipogenesis mouse 3T3-L1, human SGBS (Simpson-Golabi-Behmel syndrome) and primary human preadipocytes differentiated in vitro were used as well as primary human adipocytes to study adipocyte functions. Analysis of lipid deposition by Oil Red O staining, mRNA expression by quantitative reverse transcriptase-PCR, nuclear factor (NF)-κB activation as well as protein secretion by enzyme linked immunosorbent assay and Luminex technology was performed. RESULTS: LIGHT was found to inhibit lipid accumulation in the three models of preadipocytes in a dose-dependent manner without cytotoxic effects. This inhibition of differentiation was probably because of interference at early steps of adipogenesis, as early exposure during differentiation showed the strongest effect, as assessed by decreased peroxisome proliferator-activated receptor-γ (PPARγ) and CCAAT/enhancer-binding protein-α (C/EBPα) mRNA expression. In contrast to TNFα, basal and insulin-stimulated glucose uptake and lipolysis of terminally differentiated mature adipocytes were not altered in the presence of LIGHT. At a concentration sufficient to inhibit differentiation, secretion of proinflammatory cytokines was not significantly induced and NF-κB activity was only modestly induced compared with TNFα. CONCLUSION: LIGHT is a novel inhibitor of human adipocyte differentiation without adversely influencing central metabolic pathways in adipocytes.

Regulation of FTO and FTM expression during human preadipocyte differentiation.

In genome-wide association studies (GWAS), polymorphisms in the first intron of FTO were shown to be associated with body fat mass. However, the functional properties of FTO and its nearby gene FTM are largely unknown. We examined the expression of these genes in subcutaneous adipose tissue and in isolated preadipocytes of lean and obese women. In in vitro differentiated primary human preadipocytes and in SGBS preadipocytes we found a decline in FTO and FTM expression during adipogenic differentiation. When investigating the hormonal regulation of FTO and FTM in adipocytes, insulin was identified as a key factor regulating FTM expression indicating a potential role of FTM in insulin regulated adipocyte metabolism.

Differential expression of alternative Acyl-CoA binding protein (ACBP) transcripts in an inducible human preadipocyte cell line.

Understanding the function of fat metabolism during differentiation of human preadipocytes to fully developed fat tissue has been the aim of various studies in the past decades. Due to the lack of suitable human cell culture lines, experimental research predominantly focused on rodent models and nonhuman cell culture systems. Here, we demonstrate that a human preadipocyte cell line SGBS is well suited to examine differential expression of the Acyl-CoA binding protein (ACBP) during adipogenesis. The Acbp gene expresses various alternative high- and low-abundant transcript variants encoding ACBP protein isoforms, which play a central role in fat metabolism. Whereas the low-abundant transcript Acbp-1G is downregulated during SGBS adipogenesis, the high-abundant and well established transcripts Acbp-1A (1) and -1B are moderately (2-4-fold) upregulated. In contrast, the alternative high-abundant transcript Acbp-1C is strongly (29-fold) upregulated at mRNA and protein level indicating that particularly ACBP-1C functions in lipogenic processes during fat cell differentiation in humans.

Hypoxia induces apelin expression in human adipocytes.

Adipokines play a central role in the development of diseases associated with insulin resistance and obesity. Hypoxia in adipose tissue leads to a dysregulation of the expression of adipokines. The effect of hypoxia on the more recently identified adipokine apelin in human adipocytes is unclear. Therefore, we aimed at investigating the role of hypoxia on the expression of the adipokine apelin. Differentiated human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes were cultured under hypoxic conditions for varying time periods. A modular incubator chamber was used to create a hypoxic tissue culture environment (defined as 1% O(2), 94% N, and 5% CO(2)). In addition, hypoxic conditions were mimicked by using CoCl(2). The effect of hypoxia on the expression of the investigated adipokines was measured by real-time PCR and the secretion of apelin was quantified by ELISA. Induction of hypoxia significantly induced mRNA expression of leptin and apelin in differentiated SGBS adipocytes compared with the normoxic control condition. Expression of adiponectin was significantly decreased by hypoxia. In addition, the amount of secreted apelin protein in response to hypoxia was elevated compared to untreated cells. Furthermore, we could demonstrate that the observed hypoxia-induced induction of apelin mRNA expression is in the first phase dependent on HIF-1α. In our study, we could demonstrate for the first time that apelin expression and secretion by human adipocytes are strongly induced under hypoxic conditions and that the early response on hypoxia with apelin induction is dependent on HIF-1α.