Characterization of dedifferentiating human mature adipocytes from the 6 visceral and subcutaneous fat compartments : fibroblast-activation protein 7 alpha and Dipeptidyl peptidase 4 as major components of matrix remodeling

Mature adipocytes can reverse their phenotype to become fibroblast-like cells. This is achieved by ceiling culture and the resulting cells, called dedifferentiated fat (DFAT) cells, are multipotent. Beyond the potential value of these cells for regenerative medicine, the dedifferentiation process itself raises many questions about cellular plasticity and the pathways implicated in cell behavior. This work has been performed with the objective of obtaining new information on adipocyte dedifferentiation, especially pertaining to new targets that may be involved in cellular fate changes. To do so, omental and subcutaneous mature adipocytes sampled from severely obese subjects have been dedifferentiated by ceiling culture. An experimental design with various time points along the dedifferentiation process has been utilized to better understand this process. Cell size, gene and protein expression as well as cytokine secretion were investigated. Il-6, IL-8, SerpinE1 and VEGF secretion were increased during dedifferentiation, whereas MIF-1 secretion was transiently increased. A marked decrease in expression of mature adipocyte transcripts (PPARγ2, C/EBPα, LPL and Adiponectin) was detected early in the process. In addition, some matrix remodeling transcripts (FAP, DPP4, MMP1 and TGFβ1) were rapidly and strongly up-regulated. FAP and DPP4 proteins were simultaneously induced in dedifferentiating mature adipocytes supporting a potential role for these enzymes in adipose tissue remodeling and cell plasticity

Metabolic and cardiovascular improvements after biliopancreatic diversion in a severely obese patient

BACKGROUND: Severe obesity is associated with important morbidity and increased mortality. The successes of lifestyle modifications and drug therapy have been partial and mostly unsustained in reducing obesity and its comorbidities. Bariatric surgery, particularly biliopancreatic diversion with duodenal switch reduces efficiently excess body weight and improves metabolic and cardiovascular functions. CASE PRESENTATION: A 56-year-old man with severe clinical obesity underwent a biliopancreatic diversion with a duodenal switch after unsuccessful treatment with weight loss pharmacotherapy. He had diabetes, hypertension and sleep apnea syndrome and was on three medications for hypertension and two hypoglycemic agents in addition to > 200 insulin units daily. Eleven months after the surgery, he had lost 40% of his body weight. The lipid profile showed great improvement and the hypertension and diabetes were more easily controlled with no more insulin needed. The pseudonormalized pattern of left ventricular diastolic function improved and ventricular walls showed decreased thickness. CONCLUSION: Biliopancreatic diversion may bring metabolic and cardiovascular benefits in severely obese patients from a cardiovascular perspective

The laval questionnaire: a new instrument to measure quality of life in morbid obesity

<p>Abstract</p> <p>Background</p> <p>Our recent review of the literature uncovered eleven obesity-specific quality of life questionnaires, all with incomplete demonstration of their measurement properties. Our objective was to validate a new self-administered questionnaire specific to morbid obesity to be used in clinical trials. The study was carried out at the bariatric surgery clinic of Laval Hospital, Quebec City, Canada.</p> <p>Methods</p> <p>This study followed our description of health-related quality of life in morbid obesity from which we constructed the Laval Questionnaire. Its construct validity and responsiveness were tested by comparing the baseline and changes at 1-year follow-up in 6 domain scores (symptoms, activity/mobility, personal hygiene/clothing, emotions, social interactions, sexual life) with those of questionnaires measuring related constructs (SF-36, Impact of Weight on Quality of Life-Lite, Rosenberg Self-Esteem Scale and Beck Depression Inventory-II).</p> <p>Results</p> <p>112 patients (67 who got bariatric surgery, 45 who remained on the waiting list during the study period) participated in this study. The analysis of the discriminative function of the questionnaire showed moderate-to-high correlations between the scores in each domain of our instrument and the corresponding questionnaires. The analysis of its evaluative function showed (1) significant differences in score changes between patients with bariatric surgery and those without, and (2) moderate-to-high correlations between the changes in scores in the new instrument and the changes in the corresponding questionnaires. Most of these correlations met the <it>a priori </it>predictions we had made regarding their direction and magnitude.</p> <p>Conclusion</p> <p>The Laval Questionnaire is a valid measure of health-related quality of life in patients with morbid obesity and is responsive to treatment-induced changes.</p

Impact of Orlistat-Induced Weight Loss on Diastolic Function and Heart Rate Variability in Severely Obese Subjects with Diabetes

Objective. Determine the impact of Orlistat-induced weight loss on metabolic profile and cardiovascular function in severely obese patients with type 2 diabetes. Methods. Twenty-nine patients were randomized either to a nonplacebo control group or to a treatment group with Orlistat thrice a day. Metabolic profile, anthropometric parameters, heart rate variability indices, and echocardiographic variables were measured before and after a 12-week treatment period. Results. Treatment with Orlistat induced a modest but significant weight loss compared to controls (3.7 ± 3.0 versus 0.5 ± 2.2 kg, resp.; P = .003). There was significant decrease in fasting glycemia (7.9 ± 3.0 versus 6.7 ± 2.2 mmol/L; P = .03) and significant improvements in left ventricular diastolic function (P = .03) and in the sympathovagal balance (LF/HF ratio) (P = .04) in the Orlistat group. Conclusion. These results suggest that a modest weight loss improves fasting glycemia, left ventricular diastolic function, and sympathovagal balance in severely obese patients with type 2 diabetes

BPD-DS in the elderly

Background : Biliopancreatic diversion with duodenal switch (BPD-DS) is one of the most effective surgical approaches for the treatment of severe obesity. Objective : The objective of this study is to compare perioperative complications and long-term results of open BPD-DS in elderly versus younger patients. Methods : All patients aged 60 years and above who underwent a primary open BPD-DS in our center were selected (n = 105). Patients were matched 1:1 for sex, BMI, the presence of type 2 diabetes (T2DM), and year of surgery with a group of younger patients (aged ≤55 years). Results : The mean age of the patients was 62.3 ± 2.0 vs. 40.4 ± 7.0 years (p ≤ 0.0001). Initial BMI and prevalence of T2DM were similar in both groups, at 50.9 kg/m2 and 57 %, respectively. Mean operative time (178.6 ± 46.7 vs. 162.5 ± 39.9 min, p = 0.01), hospital stay (10.2 ± 8.3 vs. 6.3 ± 1.5 days, p = 0.0001), and blood loss (593 ± 484 vs. 474 ± 241 ml, p = 0.05) were significantly higher in elderly patients. No difference in 30-day mortality rate was observed (0.9 % in each group). There was no significant difference in major complication rate (16.2 vs. 8.6 %, p = 0.09). At a mean follow-up of 7.1 ± 4.1 years, excess weight loss (67.6 ± 19.2 vs. 72.7 ± 20.7 %, p = 0.06) and BMI (32.2 ± 5.7 vs. 30.8 ± 6.6 kg/m2, p = 0.15) were not significantly different. No significant difference was observed between the two groups for the resolution of T2DM (p = 0.53) and obstructive sleep apnea (p = 0.44). Conclusions : Open BPD-DS is associated with similar long-term benefits in elderly and younger patients, in terms of weight loss and resolution or improvement of obesity-related comorbidities. Perioperative complications might be more frequent in the elderly population, but this was not associated with increased mortality

Methylation-associated SNPs in adipose tissue

A genetic influence on methylation levels has been reported and methylation quantitative trait loci (meQTLs) have been identified in various tissues. The contribution of genetic and epigenetic factors in the development of the metabolic syndrome (MetS) has also been noted. In order to pinpoint candidate genes for testing association of SNPs with MetS and its components, we aimed to evaluate the contribution of genetic variations to differentially methylated CpG sites in severely obese men discordant for MetS. Genome-wide differential methylation analysis was conducted in visceral adipose tissue (VAT) of 31 severely obese men discordant for MetS (16 with and 15 without MetS) and identified ~17,800 variable CpG sites. Genome-wide association study conducted to identify SNPs (meQTL) associated with methylation levels at variable CpG sites revealed 2292 significant associations (P<2.22x10-11) involving 2182 unique meQTL regulating methylation levels of 174 variable CpG sites. Two meQTLs disrupting CpG sites located within the collagen encoding COL11A2 gene were tested for associations with MetS and its components in a cohort of 3021 obese individuals. Rare allele of these meQTLs showed association with plasma fasting glucose levels. Further analysis conducted on these meQTL suggested a biological impact mediated through disruption of transcription factor (TF) binding sites based on prediction of TF binding affinities. The current study identified meQTL in VAT of severely obese men and revealed associations of two COL11A2 meQTL with fasting glucose levels

Role of the TGF-β pathway in dedifferentiation of human mature adipocytes

Dedifferentiation of adipocytes contributes to the generation of a proliferative cell population that could be useful in cellular therapy or tissue engineering. Adipocytes can dedifferentiate into precursor cells to acquire a fibroblast-like phenotype using ceiling culture, in which the buoyancy of fat cells is exploited to allow them to adhere to the inner surface of a container. Ceiling culture is usually performed in flasks, which limits the ability to test various culture conditions. Using a new 6-well plate ceiling culture approach, we examined the relevance of TGF-β signaling during dedifferentiation. Adipose tissue samples from patients undergoing bariatric surgery were digested with collagenase and cell suspensions were used for ceiling cultures. Using the 6-well plate approach, cells were treated with SB431542 (an inhibitor of TGF-β receptor ALK5) or human TGF-β1 during dedifferentiation. Gene expression was measured in these cultures and in whole adipose tissue, the stromal-vascular fraction (SVF), mature adipocytes and dedifferentiated fat (DFAT) cells. TGF-β1 and collagen type I alpha 1 (COL1A1) gene expression was significantly higher in DFAT cells compared to whole adipose tissue samples and SVF cells. TGF-β1, COL1A1 and COL6A3 gene expression was significantly higher at day 12 of dedifferentiation compared to day 0. In the 6-well plate model, treatment with recombinant TGFβ1 or SB431542 respectively stimulated and inhibited the TGF-β pathway as shown by increased TGF-β1, TGF-β2, COL1A1 and COL6A3 gene expression and decreased expression of TGF-β1, COL1A1, COL1A2 and COL6A3, respectively. Treatment of DFAT cells with recombinant TGF-β1 increased the phosphorylation level of SMAD 2 and SMAD 3. Thus, a new 6-well plate model for ceiling culture allowed us to demonstrate a role for TGF-β in modulating collagen gene expression during dedifferentiation of mature adipocytes

Impact of NMT1 gene polymorphisms on features of the metabolic syndrome among severely obese patients

Introduction: N-myristoyltransferase (NMT) is implicated in myristoylation, required for biological activities of several proteins. Its gene N-myristoyltransferase 1 (NMT1) has been found to be overexpressed and hypermethylated in Visceral Adipose Tissue (VAT) of severely obese individuals with Metabolic Syndrome (MetS+) versus without (MetS-). Objective: The aim of this study was to verify the associations between NMT1 gene polymorphisms Single Nucleotide Polymorphisms (SNPs) and metabolic complications among obese subjects. Methods: Associations between SNPs and determinants of MetS were tested with 1752 obese participants undergoing a bariatric surgery. The effect of selected SNPs on methylation, and correlation with expression levels of NMT1 were verified in subgroups. Results: Rs2239921 was significantly associated with systolic (p=0.03) and diastolic (p<0.0001) blood pressures. Rs2239923 was associated with plasma High Density Lipoprotein-Cholesterol or HDL-Cholesterol (HDL-C) levels (p=0.05), while rs2269746 was associated with Low Density Lipoprotein-Cholesterol or LDL-Cholesterol (LDL-C) (p=0.006) and Total-Cholesterol (Total-C) levels (p=0.004). Rs1005136 (p=0.03), rs8066395 (p=0.03) or rs2157840 (p=0.04) were associated with plasma concentrations of C-Reactive Protein (CRP). Phenotype-associated SNPs were associated with NMT1 methylation levels of six CpG sites. NMT1 methylation levels of one CpG site, cg10755730, correlated with gene expression levels (r=0.57; p=0.04). Conclusion: These results suggest that the presence of NMT1 SNPs is associated with altered plasma lipid levels as well as with increased inflammation markers and blood pressure among severely obese patients

Gene expression variability in subcutaneous and omental adipose tissue of obese men

We investigated interindividual variability in gene expression in abdominal subcutaneous (SC) and omental (OM) adipose tissue of 10 massively obese men. Affymetrix human U133A microarrays were used to measure gene expression levels. A total of 6811 probesets generated significant signal in both depots in all samples. Interindividual variability in gene expression was rather low, with more than 90% of transcripts showing a coefficient of variation (CV) lower than 23.6% and 21.7% in OM and SC adipose tissues, respectively. The distributions of CV were similar between the two fat depots. A set of highly variable genes was identified for both tissues on the basis of a high CV and elevated gene expression level. Among the set of highly regulated genes, 18 transcripts were involved in lipid metabolism and 28 transcripts were involved in cell death for SC and OM samples, respectively. In conclusion, gene expression interindividual variability was rather low and globally similar between fat compartments, and the adipose tissue transcriptome appeared as relatively stable, although specific pathways were found to be highly variable in SC and OM depots