Validation of endogenous control genes in human adipose tissue: relevance to obesity and obesity-associated type 2 diabetes mellitus

LRP10, PGK1 and RPLP0: Best Reference Genes in Periprostatic Adipose Tissue under Obesity and Prostate Cancer Conditions

Obesity (OB) is a metabolic disorder characterized by adipose tissue dysfunction that has emerged as a health problem of epidemic proportions in recent decades. OB is associated with multiple comorbidities, including some types of cancers. Specifically, prostate cancer (PCa) has been postulated as one of the tumors that could have a causal relationship with OB. Particularly, a specialized adipose tissue (AT) depot known as periprostatic adipose tissue (PPAT) has gained increasing attention over the last few years as it could be a key player in the pathophysiological interaction between PCa and OB. However, to date, no studies have defined the most appropriate internal reference genes (IRGs) to be used in gene expression studies in this AT depot. In this work, two independent cohorts of PPAT samples (n = 20/n = 48) were used to assess the validity of a battery of 15 literature-selected IRGs using two widely used techniques (reverse transcription quantitative PCR [RT-qPCR] and microfluidic-based qPCR array). For this purpose, ΔCt method, GeNorm (v3.5), BestKeeper (v1.0), NormFinder (v.20.0), and RefFinder software were employed to assess the overall trends of our analyses. LRP10, PGK1, and RPLP0 were identified as the best IRGs to be used for gene expression studies in human PPATs, specifically when considering PCa and OB conditions.

Increased Expression Levels of Netrin-1 in Visceral Adipose Tissue during Obesity Favour Colon Cancer Cell Migration

Netrin (NTN)-1, an extracellular matrix protein with a crucial role in inflammation, is dysregulated during obesity (OB) and influences colon cancer (CC) progression. To decipher the mechanisms underlying CC development during obesity, we examined the expression of NTN1 and its receptors in the visceral adipose tissue (VAT) of 74 (25 normal weight (NW)) (16 with CC) and 49 patients with OB (12 with CC). We also evaluated the effect of caloric restriction (CR) on the gene expression levels of Ntn1 and its receptors in the colon from a rat model fed a normal diet. The impact of adipocyte-conditioned media (ACM) from patients with OB and NTN-1 was assessed on the expression levels of neogenin 1(NEO1), deleted in colorectal carcinomas (DCC) and uncoordinated-5 homolog B (UNC5B) in Caco-2 and HT-29 human colorectal cell lines, as well as on Caco-2 cell migration. Increased NTN1 and NEO1 mRNA levels in VAT were due to OB (p < 0.05) and CC (p < 0.001). In addition, an upregulation in the expression levels of DCC and UNC5B in patients with CC (p < 0.01 and p < 0.05, respectively) was observed. Decreased (p < 0.01) Ntn1 levels in the colon from rats submitted to CR were found. In vitro experiments showed that ACM increased DCC (p < 0.05) and NEO1 (p < 0.01) mRNA levels in HT-29 and Caco-2 cell lines, respectively, while UNC5B decreased (p < 0.01) in HT-29. The treatment with NTN-1 increased (p < 0.05) NEO1 mRNA levels in HT-29 cells and DCC (p < 0.05) in both cell lines. Finally, we revealed a potent migratory effect of ACM and NTN-1 on Caco-2 cells. Collectively, these findings point to increased NTN-1 during OB and CC fuelling cancer progression and exerting a strong migratory effect on colon cancer cells.

Identification of stable reference genes in peripheral blood mononuclear cells from type 2 diabetes mellitus patients

Reference genes are obligatory for accurate normalization of mRNA transcript levels across samples and experimental conditions in Real Time-polymerase chain reaction (qRT-PCR) based quantitative gene expression assays. Selection of stably expressed reference genes is therefore crucial for ensuring reproducibility of such assays. However, there is a complete dearth of data on stability of commonly used reference genes in Peripheral Blood Mononuclear Cells (PBMCs) from Type 2 diabetes mellitus (T2DM) patients. We have evaluated the gene expression stability of 4 widely used reference genes (Beta-actin, ACTB; Peptidylprolyl Isomerase B, PPIB; Tyrosine 3 Monooxygenase/Tryptophan 5-Monooxygenase Activation Protein Zeta, YWHAZ; and Glyceraldehyde-3-Phosphate Dehydrogenase, GAPDH); in PBMCs from 39 T2DM patients and 47 normoglycemic (NGT) subjects. ACTB and YWHAZ were found to be the most stable genes in PBMCs from T2DM patients and therefore, can be recommended as suitable reference genes in similar contexts. GAPDH and PPIB expressions were not stable in PBMCs from T2DM patients. On using ACTB and YWHAZ as reference genes for measuring relative expression of GAPDH and PPIB in these subjects, relative GAPDH expression was found to be significantly lower in female T2DM patients, compared to female NGT subjects [GAPDH relative normalization unit (RNU): female T2DM (n = 19), median (Q1, Q3): 9.0 (8.1, 9.9); female NGT (n = 18): median (Q1, Q3): 10.1 (9.1, 11.0); P = 0.034]. Dysregulation of GAPDH in PBMCs from female T2DM patients could be associated with sex-specific differences in pathogenesis and outcomes of T2DM.

Netrin-1 Promotes Visceral Adipose Tissue Inflammation in Obesity and Is Associated with Insulin Resistance

Netrin (NTN)-1 exhibits pro- and anti-inflammatory roles in different settings, playing important roles in the obesity-associated low-grade chronic inflammation. We aimed to determine the impact of NTN-1 on obesity and obesity-associated type 2 diabetes, as well as its role in visceral adipose tissue (VAT) inflammation. A total of 91 subjects were enrolled in this case-control study. Circulating levels of NTN-1 and its receptor neogenin (NEO)-1 were determined before and after weight loss achieved by caloric restriction and bariatric surgery. mRNA levels of NTN1 and NEO1 were assessed in human VAT, liver, and peripheral blood mononuclear cells. In vitro studies in human visceral adipocytes and human monocytic leukemia cells (THP-1)-derived macrophages were performed to analyze the impact of inflammation-related mediators on the gene expression levels of NTN1 and its receptor NEO1 as well as the effect of NTN-1 on inflammation. Increased (p < 0.001) circulating concentrations of NTN-1 in obesity decreased (p < 0.05) after diet-induced weight loss being also associated with a reduction in glucose (p < 0.01) and insulin levels (p < 0.05). Gene expression levels of NTN1 and NEO1 were upregulated (p < 0.05) in the VAT from patients with obesity with the highest expression in the stromovascular fraction cells compared with mature adipocytes (p < 0.01). NTN1 expression levels were enhanced (p < 0.01) under hypoxia and by inflammatory factors in both adipocytes and macrophages. Adipocyte-conditioned media strongly upregulated (p < 0.001) the mRNA levels of NTN1 in macrophages. The treatment of adipocytes with NTN-1 promoted the upregulation (p < 0.05) of pro-inflammatory and chemotactic molecules as well as its receptor NEO1. Collectively, these findings suggest that NTN-1 regulates VAT chronic inflammation and insulin resistance in obesity.

Improved Adipose Tissue Function after Single Anastomosis Duodeno-Ileal Bypass with Sleeve-Gastrectomy (SADI-S) in Diet-Induced Obesity

Bariatric surgery has been recognized as the safest and most effective procedure for controlling type 2 diabetes (T2D) and obesity in carefully selected patients. The aim of the present study was to compare the effects of Sleeve Gastrectomy (SG) and Single Anastomosis Duodenoileal Bypass with SG (SADI-S) on the metabolic profile of diet-induced obese rats. A total of 35 four-week-old male Wistar rats were submitted to surgical interventions (sham operation, SG and SADI-S) after 4 months of being fed a high-fat diet. Body weight, metabolic profile and the expression of molecules involved in the control of subcutaneous white (SCWAT), brown (BAT) and beige (BeAT) adipose tissue function were analyzed. SADI-S surgery was associated with significantly decreased amounts of total fat pads (p < 0.001) as well as better control of lipid and glucose metabolism compared to the SG counterparts. An improved expression of molecules involved in fat browning in SCWAT and in the control of BAT and BeAT differentiation and function was observed following SADI-S. Together, our findings provide evidence that the enhanced metabolic improvement and their continued durability after SADI-S compared to SG rely, at least in part, on the improvement of the BeAT phenotype and function.

High plasma and lingual uroguanylin as potential contributors to changes in food preference after sleeve gastrectomy

BACKGROUND

The biological mediators supporting long-term weight loss and changes in dietary choice behaviour after sleeve gastrectomy remain unclear. Guanylin and uroguanylin are gut hormones involved in the regulation of satiety, food preference and adiposity. Thus, we sought to analyze whether the guanylin system is involved in changes in food preference after sleeve gastrectomy in obesity.

METHODS

Proguanylin (GUCA2A) and prouroguanylin (GUCA2B) were determined in patients with severe obesity (n = 41) as well as in rats with diet-induced obesity (n = 48), monogenic obesity (Zucker fa/fa) (n = 18) or in a food choice paradigm (normal diet vs high-fat diet) (n = 16) submitted to sleeve gastrectomy. Lingual distribution and expression of guanylins (GUCA2A and GUCA2B) and their receptor GUCY2C as well as the fatty acid receptor CD36 were evaluated in the preclinical models.

RESULTS

Circulating concentrations of GUCA2A and GUCA2B were increased after sleeve gastrectomy in patients with severe obesity as well as in rats with diet-induced and monogenic (fa/fa) obesity. Interestingly, the lower dietary fat preference observed in obese rats under the food choice paradigm as well as in patients with obesity after sleeve gastrectomy were negatively associated with post-surgical GUCA2B levels. Moreover, sleeve gastrectomy upregulated the low expression of GUCA2A and GUCA2B in taste bud cells of tongues from rats with diet-induced and monogenic (fa/fa) obesity in parallel to a downregulation of the lingual lipid sensor CD36.

CONCLUSIONS

The increased circulating and lingual GUCA2B after sleeve gastrectomy suggest an association between the uroguanylin-GUCY2C endocrine axis and food preference through the regulation of gustatory responses.

Serum Levels of IL-1 RA Increase with Obesity and Type 2 Diabetes in Relation to Adipose Tissue Dysfunction and are Reduced After Bariatric Surgery in Parallel to Adiposity

Background

Excess adiposity leads to a dysfunctional adipose tissue that contributes to the development of obesity-associated comorbidities such as type 2 diabetes (T2D). Interleukin-1 receptor antagonist (IL-1RA) is a naturally occurring antagonist of the IL-1 receptor with anti-inflammatory properties. The aim of the present study was to compare the circulating concentrations of IL-1RA and its mRNA expression in visceral adipose tissue (VAT) in subjects with normal weight (NW), obesity with normoglycemia (OB-NG), or obesity with impaired glucose tolerance or T2D (OB-IGT&T2D) and to analyze the effect of changes in body fat percentage (BF%) on IL-1RA levels.

Methods

Serum concentrations of IL-1RA were measured in 156 volunteers. Expression of IL1RN mRNA in VAT obtained from 36 individuals was determined. In addition, the concentrations of IL-1RA were measured before and after weight gain as well as weight loss following a dietetic program or Roux-en-Y gastric bypass (RYGB).

Results

Serum levels of IL-1RA were significantly increased in individuals with obesity, being further increased in the OB-IGT&T2D group (NW 440 ± 316, OB-NG 899 ± 562, OB-IGT&T2D 1265 ± 739 pg/mL; P<0.001) and associated with markers of inflammation and fatty liver. IL1RN mRNA expression in VAT was significantly increased in the OB-IGT&T2D group and correlated in the global cohort with the mRNA expression of SPP1, CCL2, CD68, and MMP9. Levels of IL-1RA were not modified after modest changes in BF%, but RYGB-induced weight loss significantly decreased IL-1RA concentrations from 1233 ± 1009 to 660 ± 538 pg/mL (P<0.001).

Conclusion

Serum IL-1RA concentrations are increased in patients with obesity being further elevated in obesity-associated IGT and T2D in association with markers of adipose tissue dysfunction. The mRNA expression of IL1RN is markedly increased in VAT of subjects with obesity and T2D in relation with genes involved in macrophage recruitment, inflammation and matrix remodeling. Serum IL-1RA concentrations are reduced when a notable amount of BF% is loss. Measurement of IL-1RA is an excellent biomarker of adipose tissue dysfunction in obesity-associated metabolic alterations.

Impaired mRNA splicing and proteostasis in preadipocytes in obesity-related metabolic disease

Preadipocytes are crucial for healthy adipose tissue expansion. Preadipocyte differentiation is altered in obese individuals, which has been proposed to contribute to obesity-associated metabolic disturbances. Here, we aimed at identifying the pathogenic processes underlying impaired adipocyte differentiation in obese individuals with insulin resistance (IR)/type 2 diabetes (T2D). We report that down-regulation of a key member of the major spliceosome, PRFP8/PRP8, as observed in IR/T2D preadipocytes from subcutaneous (SC) fat, prevented adipogenesis by altering both the expression and splicing patterns of adipogenic transcription factors and lipid droplet-related proteins, while adipocyte differentiation was restored upon recovery of PRFP8/PRP8 normal levels. Adipocyte differentiation was also compromised under conditions of endoplasmic reticulum (ER)-associated protein degradation (ERAD) hyperactivation, as occurs in SC and omental (OM) preadipocytes in IR/T2D obesity. Thus, targeting mRNA splicing and ER proteostasis in preadipocytes could improve adipose tissue function and thus contribute to metabolic health in obese individuals.

Identifying new sperm Western blot loading controls

The measurement of protein expression level plays a pivotal role in both biological and medical studies. Housekeeping proteins, generally encoded by housekeeping genes are used as loading control proteins to normalize protein expression. Obviously, proper reference standards are essential for adequate analysis of protein expression. However, our study showed that the widely used normalisation proteins, whose expression levels varied greatly among sperm samples, were unsuitable for data standardisation. To uncover the proteins steadily expressed in sperm, we analysed several published transcriptome data of sperm. Seven proteins whose expression levels were relatively stable (co-efficient variation values less than 0.35) were selected and further evaluated by quantitative real-time polymerase chain reaction, Western Blot (WB) and immunocytochemistry. Our results showed that among the classical housekeeping proteins, only β-tubulin remained constant in sperm samples from 85 individuals. Compared with other classical housekeeping proteins such as glyceraldehyde 3-phosphate dehydrogenase, actin and histone H3, Cullin-1 (CUL1) and F-box only protein 7 (FBXO7) seemed to be more suitable to be used as internal controls for WB in sperm protein studies. Combined with the locations of these proteins, CUL1 and FBXO7 were suggested to be used as a housekeeping protein for total proteins.

Pro- and anti-inflammatory adipokines are associated with cardiometabolic risk markers in Brazilian schoolchildren

Pro- and anti-inflammatory adipokines have been regarded as potential markers of obesity and cardiometabolic comorbidities. However, few studies have evaluated this association in children. We aimed to evaluate the relationship between adipokine concentrations and cardiometabolic risk markers in Brazilian schoolchildren. This was a cross-sectional study with 378 children aged 8-9 years from Viçosa, Minas Gerais, Brazil. We measured adipokines (leptin, retinol-binding protein 4, adiponectin, and chemerin) and cardiometabolic risk markers (fasting glucose, HOMA-IR, lipid profile, and blood pressure). Cardiometabolic risk markers were compared by quintiles of adipokines with linear regression adjusted for potential confounders. Leptin was positively associated with diastolic blood pressure (P = 0.03) and HOMA-IR (P = 0.01), and retinol-binding protein 4 was positively associated with total cholesterol (P = 0.04). Each standard deviation of leptin and retinol-binding protein 4 was associated to, respectively, a 0.1 (95%CI: 0.1; 0.2), 0.3 (95%CI: 0.1; 0.6), and 2.5 (95%CI: 0.1; 4.9) units increase in diastolic blood pressure, HOMA-IR, and total cholesterol. Adiponectin was negatively associated with diastolic blood pressure (P = 0.01) and HOMA-IR (P = 0.01), and chemerin was negatively associated with glucose (P = 0.001). Each standard deviation of adiponectin and chemerin was associated to, respectively, a -0.1 (95%CI: -0.2; -0.1), -0.2 (95%CI: -0.3; -0.1), and -1.2 (95%CI: -1.9; -0.5) units decrease in diastolic blood pressure, HOMA-IR, and glucose.Conclusion: Pro- and anti-inflammatory adipokines were positively and negatively associated with cardiometabolic risk markers, respectively, among schoolchildren, indicating this relationship may be identified at earlier ages. What is Known: • Although leptin, retinol-binding protein 4, and adiponectin are well-known adipokines, a consensus regarding their relationship with cardiometabolic risk markers, especially in schoolchildren, has not yet been reached. • Chemerin is an adipokine that has been studied recently. Yet, due to its dependence on the target cell type, its functions are still a controversial topic. What is New: • Leptin was positively associated with diastolic blood pressure and HOMA-IR, and retinol-binding protein 4 was positively associated with total cholesterol. • Adiponectin was negatively associated with diastolic blood pressure and HOMA-IR, and chemerin was negatively associated with glucose.

Hepatic protective effects of Shenling Baizhu powder, a herbal compound, against inflammatory damage via TLR4/NLRP3 signalling pathway in rats with nonalcoholic fatty liver disease

OBJECTIVE

High-fat diet (HFD) and inflammation are two key contributors to nonalcoholic fatty liver disease (NAFLD). Shenling Baizhu powder (SLBZP), a classical herbal compound, has been successfully used to alleviate NAFLD. However, its specific mechanisms are not fully understood. In this study, we assessed the anti-NAFLD effect of SLBZP in vivo.

METHODS

Rats were fed an HFD with or without SLBZP or with probiotics. At the end of week 16, an echo magnetic resonance imaging (EchoMRI) body composition analyser was used to quantitatively analyse body composition; a micro-computed tomography (micro-CT) imaging system was used to evaluate whole body and liver fat; and the Moor full-field laser perfusion imager 2 was used to assess liver microcirculation, after which, all rats were sacrificed. Then, biochemical indicators in the blood and the ultrastructure of rat livers were evaluated. Protein expression related to the liver Toll-like receptor 4 (TLR4)/Nod-like receptor family pyrin domain-containing 3 (NLRP3) signalling pathway was assessed using Western blot analysis. Further, high-throughput screening of 29 related inflammatory factors in liver tissue was performed using a cytokine array.

RESULTS

SLBZP supplementation reduced body weight, serum free fatty acid, and insulin resistance index (P < 0.05). It also ameliorated liver microcirculation and ultrastructural abnormalities. EchoMRI and micro-CT quantitative analyses showed that treatment with SLBZP reduced fat mass and visceral fat (P < 0.05 and P < 0.01, respectively). In addition, SLBZP decreased the expression of lipopolysaccharide (LPS)-activated TLR4/NLRP3 signalling pathway-related proteins and altered the expression levels of some inflammatory cytokines in liver tissues.

CONCLUSION

SLBZP can inhibit NLRP3 inflammasome activation and interleukin-1β release by suppressing LPS-induced TLR4 expression in rats with HFD-induced NAFLD. Thus, SLBZP may be beneficial for the prevention and treatment of inflammatory damage and associated diseases.

Decreased Levels of Microfibril-Associated Glycoprotein (MAGP)-1 in Patients with Colon Cancer and Obesity Are Associated with Changes in Extracellular Matrix Remodelling

OBJECTIVE

The protein microfibril-associated glycoprotein (MAGP)-1 constitutes a crucial extracellular matrix protein. We aimed to determine its impact on visceral adipose tissue (VAT) remodelling during obesity-associated colon cancer (CC).

METHODS

Samples obtained from 79 subjects (29 normoponderal (NP) (17 with CC) and 50 patients with obesity (OB) (19 with CC)) were used in the study. Circulating concentrations of MAGP-1 and its gene expression levels (MFAP2) in VAT were analysed. The impact of inflammation-related factors and adipocyte-conditioned media (ACM) on MFAP2 mRNA levels in colon adenocarcinoma HT-29 cells were further analysed. The effects of MAGP-1 in the expression of genes involved in the extracellular matrix (ECM) remodelling and tumorigenesis in HT-29 cells was also explored.

RESULTS

Obesity (p < 0.01) and CC (p < 0.001) significantly decreased MFAP2 gene expression levels in VAT whereas an opposite trend in TGFB1 mRNA levels was observed. Increased mRNA levels of MFAP2 after the stimulation of HT-29 cells with lipopolysaccharide (LPS) (p < 0.01) and interleukin (IL)-4 (p < 0.01) together with a downregulation (p < 0.05) after hypoxia mimicked by CoCl₂ treatment was observed. MAGP-1 treatment significantly enhanced the mRNA levels of the ECM-remodelling genes collagen type 6 α3 chain (COL6A3) (p < 0.05), decorin (DCN) (p < 0.01), osteopontin (SPP1) (p < 0.05) and TGFB1 (p < 0.05). Furthermore, MAGP-1 significantly reduced (p < 0.05) the gene expression levels of prostaglandin-endoperoxide synthase 2 (COX2/PTGS2), a key gene controlling cell proliferation, growth and adhesion in CC. Interestingly, a significant decrease (p < 0.01) in the mRNA levels of MFAP2 in HT-29 cells preincubated with ACM from volunteers with obesity compared with control media was observed. Conclusion: The decreased levels of MAGP-1 in patients with obesity and CC together with its capacity to modulate key genes involved in ECM remodelling and tumorigenesis suggest MAGP-1 as a link between AT excess and obesity-associated CC development.

Histopathological and aquaporin7 mRNA expression analyzes in the skeletal and cardiac muscles of obese db/db mice

The aim of this study is to examine 1) muscle fiber type composition, 2) myofiber diameter, and 3) aquaporin (AQP) 7 and AQP 9 mRNA expressions by quantitative PCR in muscles of obese db/db mice. The myofiber type composition of skeletal muscle was not statistically significantly different between db/db mice and control mice; while the average myofiber diameter ratio showed a decrease in db/db mice. The expression of AQP7 but not AQP9 mRNA in the skeletal and cardiac muscles was significantly upregulated in db/db mice. Thus this study revealed quantitatively that type 2 myofiber atrophy was shown in the skeletal muscles of db/db mice. AQP7 mRNA expression was upregulated in the skeletal and cardiac muscles of db/db mice.

The associations of leptin and adiponectin with the metabolic syndrome in an Indonesian and a Dutch population

BACKGROUND AND AIMS

At the same BMI, Asian populations develop cardiometabolic complications earlier than Western populations. We hypothesized that a different secretion of the adipocyte-derived hormones leptin and adiponectin plays a role and investigated the associations of the two hormones with the metabolic syndrome (MetS) in an Indonesian and a Dutch population.

METHODS AND RESULTS

We performed cross-sectional analyses of the Netherlands Epidemiology of Obesity Study (n = 6602) and the SUGAR Scientific Programme Indonesia-Netherlands Study (n = 1461). We examined sex-stratified associations of leptin and adiponectin with MetS, using multivariate logistic regression including adjustment for total body fat. The mean (SD) leptin (mcg/L) were 4.7 (6.0) in Indonesian men, 18.6 (12.0) in Indonesian women, 9.1 (7.7) in Dutch men, and 23.4 (17.4) in Dutch women. The mean (SD) adiponectin (mg/L) were 5.7 (5.4), 7.5 (7.1), 6.6 (3.3), and 11.3 (4.9), respectively. Within the same BMI category, leptin concentrations were similar in the two populations, whereas adiponectin was lower in the Indonesian population. Per SD of leptin, adjusted prevalence odds ratios (ORs, 95%CI) of MetS were 0.9 (0.6-1.2) in Indonesian men, 1.1 (0.9-1.4) in Indonesian women, 2.2 (1.6-2.8) in Dutch men, and 1.2 (1.0-1.5) in Dutch women. Per SD of adiponectin, the ORs were 0.9 (0.7-1.2), 0.8 (0.7-1.0), 0.6 (0.6-0.8), and 0.4 (0.4-0.5), respectively.

CONCLUSIONS

Despite lower adiponectin levels, adiponectin was not related to the MetS in the Indonesian population and can not explain their increased cardiometabolic risk at the same BMI.

GLP-1 alleviates NLRP3 inflammasome-dependent inflammation in perivascular adipose tissue by inhibiting the NF-κB signalling pathway

Objectives

To study the effect of glucagon-like peptide 1 (GLP-1) on NLR family pyrin domain containing 3 (NLRP3) inflammasome-induced inflammation in perivascular adipose tissue (PVAT) of Zucker diabetic fatty (ZDF) rats and the underlying role of nuclear factor (NF)-κB signalling.

Methods

Thirty ZDF rats were randomly divided into three study groups: DM (0.9% saline, subcutaneously); DM+GLP-1 (liraglutide, s.c.); and NF-κB+GLP-1 (betulinic acid then liraglutide, s.c.). Ten Zucker lean rats were examined as normal controls. PVAT from ZDF (DM) rats was examined for inflammasome mRNA. Protein levels of NLRP3, cleaved caspase-1, caspase-1, gasdermin D (GSDMD), interleukin (IL)-1β and IL-18 in PVAT were compared between control, DM and DM+GLP-1 groups. Protein levels of NLRP3, IL-1β, IL-18 and NF-κB in PVAT were compared between control, DM, DM+GLP-1 and NF-κB+GLP-1 groups.

Results

The inflammasome most abundantly expressed in ZDF rat PVAT was NLRP3. NLRP3, cleaved caspase-1, IL-1β, IL-18, and GSDMD were markedly upregulated in DM versus control tissue, and GLP-1 reversed this effect. Inhibition of NLRP3 inflammasome-associated inflammation by GLP-1 was lost by activation of NF-κB with betulinic acid.

Conclusion

GLP-1 may alleviate NLRP3 inflammasome-dependent inflammation in PVAT by inhibiting NF-κB signalling.

Publication output of National Health Service Bariatric centres in England

Obesity has been identified as an independent risk factor for a wide range of health conditions. Therefore, there is a clear need for high quality Bariatric research in order to improve patient selection, outcomes and safety for patients with obesity. We sought to identify and compare the quantitative and qualitative publication output from Bariatric centres in England. We identified 42 National Health Service (NHS) Trusts and 162 surgeons providing Bariatric services in England. A median of 4 (range 1-7) Bariatric surgeons were identified per centre. Eight NHS Trusts (19%) and 75 surgeons (46.3%) had no Bariatric publications during the study period, while 87 surgeons published a total of 432 Bariatric papers. Only 15 surgeons (9%) had ≥10 publications within the study period. However, these surgeons produced >50% of all Bariatric publications. Departments with more than 4 surgeons produced a significantly higher number of Bariatric publications (median 8.5 vs 2, p = 0.01). There is significant variation in research contribution amongst Bariatric centres in England. Academia should be encouraged and promoted across all bariatric services in order to broaden our understanding on Bariatric outcomes by expanding the service and proportional increase in funding. Given that a number of health conditions can afflict individuals living with obesity, bariatric surgery research becomes all the more important.

Polycystic ovary syndrome: Pathways and mechanisms for possible increased susceptibility to COVID-19

In 75% of women with polycystic ovary syndrome (PCOS), insulin action is impaired. In obesity, visceral adipose tissue becomes dysfunctional: Chronic inflammation is favored over storage, contributing to the development of metabolic complications. PCOS, metabolic syndrome (MetSy) and non-alcoholic fatty liver disease (NAFLD) apparently share common pathogenic factors; these include abdominal adiposity, excess body weight and insulin resistance. Alterations in the gut microbiome have been noted in women with PCOS compared to controls; these may lead to deterioration of the intestinal barrier, increased gut mucosal permeability and immune system activation, hyperinsulinemia and glucose intolerance, which hamper normal ovarian function and follicular development (all being hallmarks of PCOS). It has been proposed that PCOS may entail higher susceptibility to coronavirus disease 2019 (COVID-19) via its associated comorbidities (NAFLD, obesity, MetSy and alterations in the gut microbiome). Studies have found an association between acute respiratory distress syndrome (seen in severe cases of COVID-19) and the intestinal microbiome. Furthermore, apparently, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can gain entry to the gastrointestinal tract via locally-expressed angiotensin converting enzyme type 2 receptors. Excess body weight is associated with more severe COVID-19 and increased mortality. Although robust links between SARS-CoV-2 infection and PCOS/NAFLD/gut microbiome/metabolic consequences are yet to be confirmed, it seems that strategies for adapting the intestinal microbiome could help reduce the severity of COVID-19 in women with PCOS with or without NAFLD, MetSy or obesity.

Leptin Is Associated with Poor Clinical Outcomes and Promotes Clear Cell Renal Cell Carcinoma Progression

Emerging evidence has shown the oncogenic roles of leptin in modulating cancer progression in addition to its original roles. Analyses of transcriptomic data and patients’ clinical information have revealed leptin’s prognostic significance in renal cell carcinoma (RCC). However, its biological effects on RCC progression have not yet been explored. Clinical and transcriptomic data of a RCC cohort of 603 patients were retrieved from The Cancer Genome Atlas (TCGA) and analyzed to reveal the correlation of leptin with clinical outcomes and the hierarchical clustering of gene signatures based on leptin levels. In addition, cox univariate and multivariate regression analyses, cell migration upon leptin treatment, identification of putative leptin-regulated canonical pathways via ingenuity pathway analysis (IPA), and the investigation of induction of Wnt5a, ROR2, and Jun N-terminal Kinases (JNK) phosphorylation activation were performed. We first observed a correlation of high leptin levels and poor outcomes in RCC patients. Knowledge-based analysis by IPA indicated the induction of cancer cell migration by leptin, which was manifested via direct leptin treatment in the RCC cell lines. In RCC patients with high leptin levels, the planar cell polarity (PCP)/JNK signaling pathway was shown to be activated, and genes in the axis, including CTHRC1, FZD2, FZD10, ROR2, WNT2, WNT4, WNT10B, WNT5A, WNT5B, and WNT7B, were upregulated. All of these genes were associated with unfavorable clinical outcomes. WNT5A and ROR2 are pivotal upstream regulators of PCP/JNK signaling, and their correlations with leptin expression levels were displayed by a Pearson correlation analysis. The inhibition of signal transduction by SP600125 reversed leptin-mediated cell migration properties in RCC cell lines. The results indicate the prognostic impact of leptin on RCC patients and uncover its ability to promote cell migration via PCP/JNK signaling.

Ubiquitin proteasome system and autophagy associated proteins in human testicular tumors

Ubiquitin proteasome sytem (UPS) and autophagy govern protein quality control by degradation and clearance of damaged proteins. Many proteins working in these pathways such as p97/VCP, Ubiquitin (Ub), Jab1/CSN5, p62, LC3B and Beclin 1 are known to be essential for different pathological conditions, especially in cancer, but their expression in human testicular tumors has not been characterized yet. In the present study, we aimed to investigate the expression of UPS (p97/VCP, Ubiquitin, Jab1/CSN5) and autophagic (p62, LC3B, Beclin 1) proteins in human testicular tumors and cancer adjacent normal testicular tissues. We used an immunohistochemical staining technique. 120 cases of testicular germ and non-germ cell tumors, which are 42 seminomas, 31 embryonal carcinomas, 11 yolk sac tumors, 25 intratubular germ cell neoplasms, 6 Leydig cell tumors, 5 Sertoli cell tumors, were collected and evaluated on tissue microarray. For the first time, the expression of p97/VCP, Ub, Jab1/CSN5, p62, LC3B and Beclin 1 in different type of human testicular tumors has been confirmed. We found that p97/VCP, Ub and Jab1/CSN5 were frequently expressed at higher levels in testicular tumours. In contrast to UPS markers, p62, LC3B and Beclin 1 showed significantly diminished expressions in testicular tumors. Accordingly, a negative correlation between p97/VCP and autophagic markers (p62 and LC3B) was found, suggesting a relationship between UPS and autophagy in different type of testicular tumors. The current results displayed elevated level of p97/VCP, Ub and Jab1/CSN5 expressions in contrast to the diminished expression of p62, LC3B and Beclin 1 in human testicular tumors, thereby supporting a correlation between p97/VCP and autophagic markers in testicular tumors.

Review, Performance Comparison, and Validation of Models Predicting Type 2 Diabetes Remission After Bariatric Surgery in a Western European Population

PURPOSE

The majority of patients with type 2 diabetes (T2DM) achieve remission after bariatric surgery. Several models are available to preoperatively predict T2DM remission. This study compares the performance of these models in a Western population one year after surgery and explores their predictive value in comparison to a model specifically designed for our study population.

MATERIALS AND METHODS

Prediction models were retrieved using a literature search. Patients were retrospectively selected from a database of the Antwerp University Hospital. Performance of the models was assessed by determining the area under the receiver operating characteristic curve (AUROC), the accuracy, and the goodness of fit, and by comparing them to a custom-made logistic model.

RESULTS

The probability of T2DM remission was calculated using 11 predictive scoring models and 8 regression models in a cohort of 250 patients. Complete T2DM remission occurred in 64.0% of patients. The IMS score (AUROC = 0.912; accuracy = 83.6%), DiaBetter score (0.907; 82.0%), and Ad-DiaRem score (0.903; 82.8%) best predicted T2DM remission and closely approached the performance of the custom-constructed model (0.917; 84.0%). The model by Ioffe et al. (0.630; 69.2%), Umemura et al. (0.692; 71.4%), and the ABCD score (0.757; 72.8%) were the least accurate.

CONCLUSION

Most T2DM remission models reliably predicted one-year T2DM remission, with limited inter-model differences. The accuracy of most models approached that of the custom-constructed model, indicating a high predictive capability and performance in our patient cohort. To date, most models are only validated to estimate T2DM remission one year after surgery and they do not predict long-term remission.

Bariatric Surgery Outcomes in Patients with Latent Autoimmune Diabetes of the Adult

Bariatric surgery is a very effective treatment for obesity-associated type 2 diabetes. However, the benefits of bariatric surgery in patients with obesity and autoimmune diabetes, such as type 1 diabetes and latent autoimmune diabetes in adults (LADA), are controversial. We report 3 female patients with obesity and LADA who underwent laparoscopic Roux-en-Y gastric bypass >10 years ago. The patients were diagnosed with LADA both 1 and 9 years before (n = 2) or 11 years after the surgery (n = 1). Patients preoperative body mass index ranged from 36 to 47 kg/m2 and improved to 23-37 kg/m2 in the last follow-up visit, 10-15 years after surgery. Daily insulin dose also decreased from an average of 0.68 to 0.45 IU/kg in those patients treated with insulin before bariatric surgery. Only one patient developed diabetes-related target organ damage. This study shows that patients with LADA depict remarkable reduction of body weight and insulin requirements over long-term after bariatric surgery. So, LADA should not be considered a contraindication for bariatric surgery yet should only be recommended for patients with concomitant obesity with the primary aim of achieving sustained weight loss.

The Association of Cortisol Excretion with Weight and Metabolic Parameters in Nondiabetic Patients with Morbid Obesity

INTRODUCTION

Cortisol is involved in the regulation of gluconeogenesis and glucose utilization. In morbid obesity (MO), the association of cortisol excretion with metabolic parameters is not well-characterized. In our study, we evaluated cortisol excretion in nondiabetic subjects with MO and its effect on glucose metabolism.

METHODS

We included 1,249 nondiabetic patients with MO (79.8% females, mean BMI 44.9 ± 6.5 kg/m2, mean age 38 ± 11 years). Anthropometric data and cardiovascular risk factors were assessed, and an oral glucose tolerance test for calculation of insulin resistance was performed. Cortisol excretion was assessed on 2 consecutive days (24 h urine specimens).

RESULTS

Regarding cortisol excretion, patients were divided into 3 tertiles (urinary cortisol ≤51.6, >51.6 and <117.6, and ≥117.6 μg/24 h, respectively). Patients in the highest tertile were younger (p = 0.003), more obese (BMI: p = 0.040), had lower diastolic blood pressure ([DBP]; p = 0.012), lower total (p = 0.032) and LDL cholesterol (p = 0.021), fasting (p = 0.049) and 2-h glycemia (p = 0.028), 2-h insulinemia (p = 0.020), and HbA1c (p < 0.001), and a higher estimated glomerular filtration rate (eGFR) (p < 0.001). The glucose (p < 0.001) and insulin (p = 0.011) area under the curve (AUC) were also lower. Urinary cortisol excretion adjusted for age, sex, and eGFR was positively correlated with body weight (BW, beta = 0.076, p = 0.004) and overall glucose tolerance (oral disposition index, beta = 0.090, p = 0.011), and negatively with HbA1c (beta = -0.179, p < 0.001), 2-h glycemia (beta = -0.075, p = 0.032), AUC glucose (beta = -0.103, p = 0.002), and DBP (beta = -0.139, p < 0.001). HbA1c, BW, and DBP remained significant after multivariable analysis.

DISCUSSION/CONCLUSION

Despite being more obese, patients with higher cortisol excretion have a more favorable metabolic profile. These results deserve further attention regarding the respective mechanisms.

Generation of immune cell containing adipose organoids for in vitro analysis of immune metabolism

Adipose tissue is an organized endocrine organ with important metabolic and immunological functions and immune cell-adipocyte crosstalk is known to drive various disease pathologies. Suitable 3D adipose tissue organoid models often lack resident immune cell populations and therefore require the addition of immune cells isolated from other organs. We have created the first 3D adipose tissue organoid model which could contain and maintain resident immune cell populations of the stromal vascular fraction (SVF) and proved to be effective in studying adipose tissue biology in a convenient manner. Macrophage and mast cell populations were successfully confirmed within our organoid model and were maintained in culture without the addition of growth factors. We demonstrated the suitability of our model for monitoring the lipidome during adipocyte differentiation in vitro and confirmed that this model reflects the physiological lipidome better than standard 2D cultures. In addition, we applied mass spectrometry-based lipidomics to track lipidomic changes in the lipidome upon dietary and immunomodulatory interventions. We conclude that this model represents a valuable tool for immune-metabolic research.

High-Fat Diet Alters the Expression of Reference Genes in Male Mice

Quantitative PCR (qPCR), the most accurate and sensitive technique for quantifying mRNA expression, and choice of appropriate reference genes for internal error controlling in qPCR are essential to understanding the molecular mechanisms that drive the obesity epidemic and its comorbidities. In this study, using the high-fat diet (HFD)-induced obese mouse model, we assessed the expression of 10 commonly used reference genes to validate gene-expression stability in adipose tissue, liver, and muscle across different time points (4, 8, 12, and 16 weeks after HFD feeding) during the process of obesity. The data were analyzed by the GeNorm, NormFinder, BestKeeper, and Delta-Ct method, and the results showed that the most stable reference genes were different for a specific organ or tissue in a specific time point; however, PPIA, RPLP0, and YWHAZ were the top three most stable reference genes in qPCR experiments on adipose, hepatic tissues, and muscles of mice in diet-induced obesity. In addition, the mostly used genes ACTB and GAPDH were more unstable in the fat and liver, the ACTB mRNA levels were increased in four adipose tissues, and the GAPDH mRNA levels were decreased in four adipose tissues and liver after HFD feeding. These results suggest that PPIA, RPLP0, or YWHAZ may be more appropriate to be used as reference gene than ACTB and GAPDH in the adipose tissue and liver of mice during the process of high-fat diet-induced obesity.

Prevention of Diabetes and Cardiovascular Disease in Obesity

Obesity is one of the major risk factors for the development of both impaired glucose tolerance (IGT, or prediabetes) and type 2 diabetes (T2D), and its prevalence worldwide drives toward an increased rate of cardiovascular morbidity and mortality. Given the estimations of the World Health Organization (WHO) and the recommendation of the Diabetes Prevention Program (DPP), where IGT and diabetes are considered as risk factors for the development of cardiovascular complications and obesity, the development of diabetes should be treated because of its potential reversibility. In this view, several interventions such as diet, lifestyle changes, and pharmacological treatment are effective, including bariatric metabolic surgery (BMS), which is the most incisive way to efficiently lower body weight. In this review, we sought to summarize some of the major aspects linked to diabetes prevention in overweight/obesity, focusing on the use of surgery; we also attempted to elucidate molecular pathways involved in a variety of obesity-induced processes able to favor the progression of chronic diseases, such as diabetes and its complications.

NLRP3 inflammasome blockade reduces adipose tissue inflammation and extracellular matrix remodeling

The NLRP3-IL-1β pathway plays an important role in adipose tissue (AT)-induced inflammation and the development of obesity-associated comorbidities. We aimed to determine the impact of NLRP3 on obesity and its associated metabolic alterations as well as its role in adipocyte inflammation and extracellular matrix (ECM) remodeling. Samples obtained from 98 subjects were used in a case-control study. The expression of different components of the inflammasome as well as their main effectors and inflammation- and ECM remodeling-related genes were analyzed. The impact of blocking NLRP3 using siRNA in lipopolysaccharide (LPS)-mediated inflammation and ECM remodeling signaling pathways was evaluated. We demonstrated that obesity (P < 0.01), obesity-associated T2D (P < 0.01) and NAFLD (P < 0.05) increased the expression of different components of the inflammasome as well as the expression and release of IL-1β and IL-18 in AT. We also found that obese patients with T2D exhibited increased (P < 0.05) hepatic gene expression levels of NLRP3, IL1B and IL18. We showed that NLRP3, but not NLRP1, is regulated by inflammation and hypoxia in visceral adipocytes. We revealed that the inhibition of NLRP3 in human visceral adipocytes significantly blocked (P < 0.01) LPS-induced inflammation by downregulating the mRNA levels of CCL2, IL1B, IL6, IL8, S100A8, S100A9, TLR4 and TNF as well as inhibiting (P < 0.01) the secretion of IL1-β into the culture medium. Furthermore, blocking NLRP3 attenuated (P < 0.01) the LPS-induced expression of important molecules involved in AT fibrosis (COL1A1, COL4A3, COL6A3 and MMP2). These novel findings provide evidence that blocking the expression of NLRP3 reduces AT inflammation with significant fibrosis attenuation.

Role of ghrelin isoforms in the mitigation of hepatic inflammation, mitochondrial dysfunction, and endoplasmic reticulum stress after bariatric surgery in rats

BACKGROUND/OBJECTIVES

Bariatric surgery improves nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH), but the underlying mechanisms remain elusive. We evaluated the potential role of ghrelin isoforms in the amelioration of hepatic inflammation after sleeve gastrectomy and Roux-en-Y gastric bypass (RYGB).

SUBJECTS/METHODS

Plasma ghrelin isoforms were measured in male Wistar rats (n = 129) subjected to surgical (sham operation, sleeve gastrectomy, or RYGB) or dietary interventions [fed ad libitum a normal (ND) or a high-fat diet (HFD) or pair-fed diet]. The effect of acylated and desacyl ghrelin on markers of inflammation, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress in primary rat hepatocytes under palmitate-induced lipotoxic conditions was assessed.

RESULTS

Plasma desacyl ghrelin was decreased after sleeve gastrectomy and RYGB, whereas the acylated/desacyl ghrelin ratio was augmented. Both surgeries diminished obesity-associated hepatic steatosis, CD68⁺- and apoptotic cells, proinflammatory JNK activation, and Crp, Tnf, and Il6 transcripts. Moreover, a postsurgical amelioration in the mitochondrial DNA content, oxidative phosphorylation (OXPHOS) complexes I and II, and ER stress markers was observed. Specifically, following bariatric surgery GRP78, spliced XBP-1, ATF4, and CHOP levels were reduced, as were phosphorylated eIF2α. Interestingly, acylated and desacyl ghrelin inhibited steatosis and inflammation of palmitate-treated hepatocytes in parallel to an upregulation of OXPHOS complexes II, III, and V, and a downregulation of ER stress transducers IRE1α, PERK, ATF6, their downstream effectors, ATF4 and CHOP, as well as chaperone GRP78.

CONCLUSIONS

Our data suggest that the increased relative acylated ghrelin levels after bariatric surgery might contribute to mitigate obesity-associated hepatic inflammation, mitochondrial dysfunction, and ER stress.

GLP-1 Limits Adipocyte Inflammation and Its Low Circulating Pre-Operative Concentrations Predict Worse Type 2 Diabetes Remission after Bariatric Surgery in Obese Patients

OBJECTIVE

Glucagon-like peptide (GLP)-1 has been proposed as a key candidate in glucose improvements after bariatric surgery. Our aim was to explore the role of GLP-1 in surgically-induced type 2 diabetes (T2D) improvement and its capacity to regulate human adipocyte inflammation.

METHODS

Basal circulating concentrations of GLP-1 as well as during an oral glucose tolerance test (OGTT) were measured in lean and obese volunteers with and without T2D (n = 93). In addition, GLP-1 levels were determined before and after weight loss achieved by Roux-en-Y gastric bypass (RYGB) (n = 77). The impact of GLP-1 on inflammation signalling pathways was also evaluated.

RESULTS

We show that the reduced (p < 0.05) circulating levels of GLP-1 in obese T2D patients increased (p < 0.05) after RYGB. The area under the curve was significantly lower in obese patients with (p < 0.01) and without (p < 0.05) T2D compared to lean volunteers while obese patients with T2D exhibited decreased GLP-1 levels at baseline (p < 0.05) and 120 min (p < 0.01) after the OGTT. Importantly, higher (p < 0.05) pre-operative GLP-1 concentrations were found in patients with T2D remission after RYGB. We also revealed that exendin-4, a GLP-1 agonist, downregulated the expression of inflammation-related genes (IL1B, IL6, IL8, TNF) and, conversely, upregulated the mRNA levels of ADIPOQ in human visceral adipocytes. Furthermore, exendin-4 blocked (p < 0.05) LPS-induced inflammation in human adipocytes via downregulating the expression and secretion of key inflammatory markers.

CONCLUSIONS

Our data indicate that GLP-1 may contribute to glycemic control and exert a role in T2D remission after RYGB. GLP-1 is also involved in limiting inflammation in human visceral adipocytes.

iNOS Gene Ablation Prevents Liver Fibrosis in Leptin-Deficient ob/ob Mice

The role of extracellular matrix (ECM) remodeling in fibrosis progression in nonalcoholic fatty liver disease (NAFLD) is complex and dynamic, involving the synthesis and degradation of different ECM components, including tenascin C (TNC). The aim was to analyze the influence of inducible nitric oxide synthase (iNOS) deletion on inflammation and ECM remodeling in the liver of ob/ob mice, since a functional relationship between leptin and iNOS has been described. The expression of molecules involved in inflammation and ECM remodeling was analyzed in the liver of double knockout (DBKO) mice simultaneously lacking the ob and the iNOS genes. Moreover, the effect of leptin was studied in the livers of ob/ob mice and compared to wild-type rodents. Liver inflammation and fibrosis were increased in leptin-deficient mice. As expected, leptin treatment reverted the obesity phenotype. iNOS deletion in ob/ob mice improved insulin sensitivity, inflammation, and fibrogenesis, as evidenced by lower macrophage infiltration and collagen deposition as well as downregulation of the proinflammatory and profibrogenic genes including Tnc. Circulating TNC levels were also decreased. Furthermore, leptin upregulated TNC expression and release via NO-dependent mechanisms in AML12 hepatic cells. iNOS deficiency in ob/ob mice improved liver inflammation and ECM remodeling-related genes, decreasing fibrosis, and metabolic dysfunction. The activation of iNOS by leptin is necessary for the synthesis and secretion of TNC in hepatocytes, suggesting an important role of this alarmin in the development of NAFLD.

Intraindividual Variation in Markers of Intestinal Permeability and Adipose Tissue Inflammation in Healthy Normal-Weight to Obese Adults

BACKGROUND

Intestinal permeability and adipose tissue inflammation are considered mechanistic links in the relationship between diet, obesity, and chronic disease. However, methods to measure both are not well standardized, and the reliability of commonly used measures is not known.

METHODS

We calculated the intraclass correlation coefficient (ICC) for several common measures of intestinal permeability and adipose tissue inflammation from a randomized clinical trial of cross-over design in which normal-weight (n = 12) or overweight/obese (n = 12) individuals each completed three 8-day dietary intervention periods.

RESULTS

For biomarkers of intestinal permeability, plasma zonulin, and lipopolysaccharide-binding protein, ICCs were "excellent" (i.e., >0.9). The direct measure of intestinal permeability, the lactulose/mannitol test, exhibited "fair" reliability (ICC = 0.53). A wider range of ICCs (0.6-0.9), suggesting "good" to "excellent" reliability, were obtained for measures of adipose tissue expression of genes encoding major mediators of inflammation. Similarly, individual immune cell populations isolated from adipose tissue, expressed as a percentage of all CD45⁺ cells, also had "good" to "excellent" ICCs. However, when these populations were expressed as number of cells per gram of tissue, ICC values were "fair," falling below 0.6.

CONCLUSIONS

Due to the repeated measures design, our study offered a unique opportunity to assess reliability of commonly used biomarkers of intestinal permeability and adipose tissue inflammation. Our findings suggest that these measures were generally highly reliable in the short-term.

IMPACT

Along with other factors, particularly validity, the demonstrated reliabilities can help inform the choice of endpoints in studies of intestinal permeability and adipose tissue inflammation.

NLRP3 Inflammasome: A Possible Link Between Obesity-Associated Low-Grade Chronic Inflammation and Colorectal Cancer Development

Emerging evidence reveals that adipose tissue-associated inflammation is a main mechanism whereby obesity promotes colorectal cancer risk and progression. Increased inflammasome activity in adipose tissue has been proposed as an important mediator of obesity-induced inflammation and insulin resistance development. Chronic inflammation in tumor microenvironments has a great impact on tumor development and immunity, representing a key factor in the response to therapy. In this context, the inflammasomes, main components of the innate immune system, play an important role in cancer development showing tumor promoting or tumor suppressive actions depending on the type of tumor, the specific inflammasome involved, and the downstream effector molecules. The inflammasomes are large multiprotein complexes with the capacity to regulate the activation of caspase-1. In turn, caspase-1 enhances the proteolytic cleavage and the secretion of the inflammatory cytokines interleukin (IL)-1β and IL-18, leading to infiltration of more immune cells and resulting in the generation and maintenance of an inflammatory microenvironment surrounding cancer cells. The inflammasomes also regulate pyroptosis, a rapid and inflammation-associated form of cell death. Recent studies indicate that the inflammasomes can be activated by fatty acids and high glucose levels linking metabolic danger signals to the activation of inflammation and cancer development. These data suggest that activation of the inflammasomes may represent a crucial step in the obesity-associated cancer development. This review will also focus on the potential of inflammasome-activated pathways to develop new therapeutic strategies for the prevention and treatment of obesity-associated colorectal cancer development.

Novel protective role of kallistatin in obesity by limiting adipose tissue low grade inflammation and oxidative stress

OBJECTIVE

Kallistatin plays an important role in the inhibition of inflammation, oxidative stress, fibrosis and angiogenesis. We aimed to determine the impact of kallistatin on obesity and its associated metabolic alterations as well as its role in adipocyte inflammation and oxidative stress.

METHODS

Samples obtained from 95 subjects were used in a case-control study. Circulating concentrations and expression levels of kallistatin as well as key inflammation, oxidative stress and extracellular matrix remodelling-related genes were analyzed. Circulating kallistatin concentrations were measured before and after weight loss achieved by Roux-en-Y gastric bypass (RYGB). The impact of kallistatin on lipopolysaccharide (LPS)- and tumour necrosis factor (TNF)-α-mediated inflammatory as well as oxidative stress signalling pathways was evaluated.

RESULTS

We show that the reduced (P < 0.00001) circulating levels of kallistatin in obese patients increased (P < 0.00001) after RYGB. Moreover, gene expression levels of SERPINA4, the gene coding for kallistatin, were downregulated (P < 0.01) in the liver from obese subjects with non-alcoholic fatty liver disease. Additionally, we revealed that kallistatin reduced (P < 0.05) the expression of inflammation-related genes (CCL2, IL1B, IL6, IL8, TNFA, TGFB) and, conversely, upregulated (P < 0.05) mRNA levels of ADIPOQ and KLF4 in human adipocytes in culture. Kallistatin inhibited (P < 0.05) LPS- and TNF-α-induced inflammation in human adipocytes via downregulating the expression and secretion of key inflammatory markers. Furthermore, kallistatin also blocked (P < 0.05) TNF-α-mediated lipid peroxidation as well as NOX2 and HIF1A expression while stimulating (P < 0.05) the expression of SIRT1 and FOXO1.

CONCLUSIONS

These findings provide, for the first time, evidence of a novel role of kallistatin in obesity and its associated comorbidities by limiting adipose tissue inflammation and oxidative stress.

The caveolae-associated coiled-coil protein, NECC2, regulates insulin signalling in Adipocytes

Adipocyte dysfunction in obesity is commonly associated with impaired insulin signalling in adipocytes and insulin resistance. Insulin signalling has been associated with caveolae, which are coated by large complexes of caveolin and cavin proteins, along with proteins with membrane-binding and remodelling properties. Here, we analysed the regulation and function of a component of caveolae involved in growth factor signalling in neuroendocrine cells, neuroendocrine long coiled-coil protein-2 (NECC2), in adipocytes. Studies in 3T3-L1 cells showed that NECC2 expression increased during adipogenesis. Furthermore, NECC2 co-immunoprecipitated with caveolin-1 (CAV1) and exhibited a distribution pattern similar to that of the components of adipocyte caveolae, CAV1, Cavin1, the insulin receptor and cortical actin. Interestingly, NECC2 overexpression enhanced insulin-activated Akt phosphorylation, whereas NECC2 downregulation impaired insulin-induced phosphorylation of Akt and ERK2. Finally, an up-regulation of NECC2 in subcutaneous and omental adipose tissue was found in association with human obesity and insulin resistance. This effect was also observed in 3T3-L1 adipocytes exposed to hyperglycaemia/hyperinsulinemia. Overall, the present study identifies NECC2 as a component of adipocyte caveolae that is regulated in response to obesity and associated metabolic complications, and supports the contribution of this protein as a molecular scaffold modulating insulin signal transduction at these membrane microdomains.

Targeted disruption of the iNOS gene improves adipose tissue inflammation and fibrosis in leptin-deficient ob/ob mice: role of tenascin C

BACKGROUND/OBJECTIVES

Obesity is related to a dynamic extracellular matrix (ECM) remodeling, which involves the synthesis and degradation of different proteins, such as tenascin C (TNC) in the adipose tissue (AT). Given the functional relationship between leptin and inducible nitric oxide synthase (iNOS), our aim was to analyze the impact of the absence of the iNOS gene in AT inflammation and ECM remodeling in ob/ob mice.

SUBJECTS/METHODS

The expression of genes involved in inflammation and ECM remodeling was evaluated in 10-week-old male double knockout (DBKO) mice simultaneously lacking the ob and iNOS genes as well as in ob/ob mice classified into three groups [control, leptin-treated (1 mg kg^-1 day^-1) and pair-fed].

RESULTS

Leptin deficiency increased inflammation and fibrosis in AT. As expected, leptin treatment improved the obesity phenotype. iNOS deficiency in ob/ob mice improved insulin sensitivity, AT inflammation, and ECM remodeling, as evidenced by lower AT macrophage infiltration and collagen deposition, a downregulation of proinflammatory and profibrogenic genes Tnf, Emr1, Hif1a, Col6a1, Col6a3, and Tnc, as well as lower circulating TNC levels. Interestingly, leptin upregulated TNC expression and release in 3T3-L1 adipocytes, and iNOS knockdown in 3T3-L1 fat cells produced a significant decrease in basal and leptin-induced Tnc expression.

CONCLUSIONS

Ablation of iNOS in leptin-deficient mice improved AT inflammation and ECM remodeling-related genes, attenuating fibrosis, and metabolic dysfunction. The activation of iNOS by leptin is necessary for the synthesis and secretion of TNC in adipocytes, suggesting an important role of this alarmin in the development of AT inflammation and fibrosis.

Gastric Plication Improves Glycemia Partly by Restoring the Altered Expression of Aquaglyceroporins in Adipose Tissue and the Liver in Obese Rats

BACKGROUND

Gastric plication is a minimally invasive bariatric surgical procedure, where the greater curvature is plicated inside the gastric lumen. Our aims were to analyze the effectiveness of gastric plication on the resolution of obesity, impaired glucose tolerance, and fatty liver in an experimental model of diet-induced obesity (DIO) and to evaluate changes in glycerol metabolism, a key substrate for adiposity and gluconeogenesis, in adipose tissue and the liver.

METHODS

Male Wistar DIO rats (n = 58) were subjected to surgical (sham operation and gastric plication) or dietary interventions [fed a normal diet (ND) or high-fat diet (HFD) or pair-fed to the amount of food eaten by gastric-plicated animals]. The expression of aquaglyceroporins (AQPs) in epididymal (EWAT) and subcutaneous (SCWAT) fat and the liver was analyzed by real-time PCR and Western blot.

RESULTS

Gastric plication did not result in a significant weight loss in DIO rats, showing a modest reduction in whole-body adiposity and hepatic steatosis. However, gastric-plicated animals exhibited an improvement in basal glycemia and glucose clearance, without changes in hepatic gluconeogenic genes. DIO was associated with an increase in glycerol, higher AQP3 and AQP7 in EWAT and SCWAT, and a decrease in hepatic AQP9. Gastric plication downregulated AQP3 in both fat depots without changes in adipose AQP7 and hepatic AQP9.

CONCLUSION

Gastric plication results in a modest reduction in adiposity and hepatosteatosis but restores glycemia by downregulating AQP3, which entails lower efflux of glycerol from fat, lower plasma glycerol availability, and a reduced use of glycerol as a substrate for hepatic gluconeogenesis.

Circulating sex steroids coregulate adipose tissue immune cell populations in healthy men

Male hypogonadism results in changes in body composition characterized by increases in fat mass. Resident immune cells influence energy metabolism in adipose tissue and could promote increased adiposity through paracrine effects. We hypothesized that manipulation of circulating sex steroid levels in healthy men would alter adipose tissue immune cell populations. Subjects (n = 44 men, 19-55 yr of age) received 4 wk of treatment with the gonadotropin-releasing hormone receptor antagonist acyline with daily administration of 1) placebo gel, 2) 1.25 g testosterone gel (1.62%), 3) 5 g testosterone gel, or 4) 5 g testosterone gel with an aromatase inhibitor. Subcutaneous adipose tissue biopsies were performed at baseline and end-of-treatment, and adipose tissue immune cells, gene expression, and intra-adipose estrogen levels were quantified. Change in serum total testosterone level correlated inversely with change in the number of CD3⁺ (β = -0.36, P = 0.04), CD4⁺ (β = -0.34, P = 0.04), and CD8⁺ (β = -0.33, P = 0.05) T cells within adipose tissue. Change in serum 17β-estradiol level correlated inversely with change in the number of adipose tissue macrophages (ATMs) (β = -0.34, P = 0.05). A negative association also was found between change in serum testosterone and change in CD11c⁺ ATMs (β = -0.41, P = 0.01). Overall, sex steroid deprivation was associated with increases in adipose tissue T cells and ATMs. No associations were found between changes in serum sex steroid levels and changes in adipose tissue gene expression. Circulating sex steroid levels may regulate adipose tissue immune cell populations. These exploratory findings highlight a possible novel mechanism that could contribute to increased metabolic risk in hypogonadal men.

Normalization of adiponectin concentrations by leptin replacement in ob/ob mice is accompanied by reductions in systemic oxidative stress and inflammation

The circulating concentrations of adiponectin, an antidiabetic adipokine, have been shown to be reduced in obesity, in relation to an increase in inflammation. The aim of the present work was to assess the effect of leptin replacement on adiponectin levels and expression as well as on markers of oxidative stress and inflammation in leptin-deficient ob/ob mice. Twelve-week-old male mice (n = 7–10 per group) were treated with either saline (wild type and ob/ob mice) or leptin (ob/ob mice) for 18 days. A third group of ob/ob mice was treated with saline and pair-fed to the amount of food consumed by the leptin-treated group. Leptin replacement restored values of adiponectin (P < 0.001), reduced circulating 8-isoprostane and serum amyloid A (SAA) levels (P < 0.05 for both), and significantly downregulated the increased gene expression of osteopontin (Spp1, P < 0.05), Saa3 (P < 0.05), Cd68 (P < 0.01), Il6 (P < 0.01) and NADPH oxidase (Nox1 and Nox2, P < 0.01) in the perirenal WAT and Spp1 (P < 0.05) in the liver of ob/ob mice. In cultured adipocytes from ob/ob mice, leptin increased (P < 0.05) the mRNA expression and secretion of adiponectin. We concluded that circulating concentrations of adiponectin are positively regulated by leptin and ameliorate obesity-associated oxidative stress and inflammation in mice.

The short-term and long-term effects of bariatric/metabolic surgery on subcutaneous adipose tissue inflammation in humans

CONTEXT

The mechanisms mediating the short- and long-term improvements in glucose homeostasis following bariatric/metabolic surgery remain incompletely understood.

OBJECTIVE

To investigate whether a reduction in adipose tissue inflammation plays a role in the metabolic improvements seen after bariatric/metabolic surgery, both in the short-term and longer-term.

DESIGN

Fasting blood and subcutaneous abdominal adipose tissue were obtained before (n=14), at one month (n=9), and 6-12months (n=14) after bariatric/metabolic surgery from individuals with obesity who were not on insulin or anti-diabetes medication. Adipose tissue inflammation was assessed by a combination of whole-tissue gene expression and flow cytometry-based quantification of tissue leukocytes.

RESULTS

One month after surgery, body weight was reduced by 13.5±4.4kg (p<0.001), with improvements in glucose tolerance reflected by a decrease in area-under-the-curve (AUC) glucose in 3-h oral glucose tolerance tests (-105±98mmol/L * min; p=0.009) and enhanced pancreatic β-cell function (insulinogenic index: +0.8±0.9pmol/mmol; p=0.032), but no change in estimated insulin sensitivity (Matsuda insulin sensitivity index [ISI]; p=0.720). Furthermore, although biomarkers of systemic inflammation and pro-inflammatory gene expression in adipose tissue remained unchanged, the number of neutrophils increased in adipose tissue 15-20 fold (p<0.001), with less substantial increases in other leukocyte populations. By the 6-12month follow-up visit, body weight was reduced by 34.8±10.8kg (p<0.001) relative to baseline, and glucose tolerance was further improved (AUC glucose -276±229; p<0.001) along with estimated insulin sensitivity (Matsuda ISI: +4.6±3.2; p<0.001). In addition, improvements in systemic inflammation were reflected by reductions in circulating C-reactive protein (CRP; -2.0±5.3mg/dL; p=0.002), and increased serum adiponectin (+1358±1406pg/mL; p=0.003). However, leukocyte infiltration of adipose tissue remained elevated relative to baseline, with pro-inflammatory cytokine mRNA expression unchanged, while adiponectin mRNA expression trended downward (p=0.069).

CONCLUSION

Both the short- and longer-term metabolic improvements following bariatric/metabolic surgery occur without significant reductions in measures of adipose tissue inflammation, as assessed by measuring the expression of genes encoding key mediators of inflammation and by flow cytometric immunophenotyping and quantification of adipose tissue leukocytes.

Effects of dietary supplementation with EPA and/or α-lipoic acid on adipose tissue transcriptomic profile of healthy overweight/obese women following a hypocaloric diet

In obesity, the increment of adiposity levels disrupts the whole body homeostasis, promoting an over production of oxidants and inflammatory mediators. The current study aimed to characterize the transcriptomic changes promoted by supplementation with eicosapentaenoic acid (EPA, 1.3 g/day), α-lipoic acid (0.3 g/day), or both (EPA + α-lipoic acid, 1.3 g/day + 0.3 g/day) in subcutaneous abdominal adipose tissue from overweight/obese healthy women, who followed a hypocaloric diet (30% of total energy expenditure) during ten weeks, by using a microarray approach. At the end of the intervention, a total of 33,297 genes were analyzed using Affymetrix GeneChip arrays. EPA promoted changes in extracellular matrix remodeling gene expression, besides a rise of genes associated with either chemotaxis or wound repair. α-Lipoic acid decreased expression of genes related with cell adhesion and inflammation. Furthermore, α-lipoic acid, especially in combination with EPA, upregulated the expression of genes associated with lipid catabolism while downregulated genes involved in lipids storage. Together, all these data suggest that some of the metabolic effects of EPA and α-lipoic acid could be related to their regulatory actions on adipose tissue metabolism. © 2016 BioFactors, 43(1):117-131, 2017.

Acylated and desacyl ghrelin are associated with hepatic lipogenesis, β-oxidation and autophagy: role in NAFLD amelioration after sleeve gastrectomy in obese rats

Bariatric surgery improves non-alcoholic fatty liver disease (NAFLD). Our aim was to investigate the potential role of ghrelin isoforms in the resolution of hepatic steatosis after sleeve gastrectomy, a restrictive bariatric surgery procedure, in diet-induced obese rats. Male Wistar rats (n = 161) were subjected to surgical (sham operation and sleeve gastrectomy) or dietary interventions [fed ad libitum a normal (ND) or a high-fat (HFD) diet or pair-fed]. Obese rats developed hepatosteatosis and showed decreased circulating desacyl ghrelin without changes in acylated ghrelin. Sleeve gastrectomy induced a dramatic decrease of desacyl ghrelin, but increased the acylated/desacyl ghrelin ratio. Moreover, sleeve gastrectomy reduced hepatic triglyceride content and lipogenic enzymes Mogat2 and Dgat1, increased mitochondrial DNA amount and induced AMPK-activated mitochondrial FFA β-oxidation and autophagy to a higher extent than caloric restriction. In primary rat hepatocytes, the incubation with both acylated and desacyl ghrelin (10, 100 and 1,000 pmol/L) significantly increased TG content, triggered AMPK-activated mitochondrial FFA β-oxidation and autophagy. Our data suggest that the decrease in the most abundant isoform, desacyl ghrelin, after sleeve gastrectomy contributes to the reduction of lipogenesis, whereas the increased relative acylated ghrelin levels activate factors involved in mitochondrial FFA β-oxidation and autophagy in obese rats, thereby ameliorating NAFLD.

Evaluation of candidate reference genes for RT-qPCR studies in three metabolism related tissues of mice after caloric restriction

Reverse transcription quantitative-polymerase chain reaction (RT-qPCR) is a routine method for gene expression analysis, and reliable results depend on proper normalization by stable reference genes. Caloric restriction (CR) is a robust lifestyle intervention to slow aging and delay onset of age-associated diseases via inducing global changes in gene expression. Reliable normalization of RT-qPCR data becomes crucial in CR studies. In this study, the expression stability of 12 candidate reference genes were evaluated in inguinal white adipose tissue (iWAT), skeletal muscle (Sk.M) and liver of CR mice by using three algorithms, geNorm, NormFinder, and Bestkeeper. Our results showed β2m, Ppia and Hmbs as the most stable genes in iWAT, Sk.M and liver, respectively. Moreover, two reference genes were sufficient to normalize RT-qPCR data in each tissue and the suitable pair of reference genes was β2m-Hprt in iWAT, Ppia-Gusb in Sk.M and Hmbs-β2m in liver. By contrast, the least stable gene in iWAT or Sk.M was Gapdh, and in liver was Pgk1. Furthermore, the expression of Leptin and Ppar-γ were profiled in these tissues to validate the selected reference genes. Our data provided a basis for gene expression analysis in future CR studies.

Increased Interleukin-32 Levels in Obesity Promote Adipose Tissue Inflammation and Extracellular Matrix Remodeling: Effect of Weight Loss

Interleukin (IL)-32 is a recently described cytokine involved in the regulation of inflammation. We aimed to explore whether IL-32 could function as an inflammatory and angiogenic factor in human obesity and obesity-associated type 2 diabetes. Samples obtained from 90 subjects were used in the study. Obese patients exhibited higher expression levels of IL-32 in visceral adipose tissue (AT) as well as in subcutaneous AT and peripheral blood mononuclear cells. IL32 was mainly expressed by stromovascular fraction cells, and its expression was significantly enhanced by inflammatory stimuli and hypoxia, whereas no changes were found after the incubation with anti-inflammatory cytokines. The addition of exogenous IL-32 induced the expression of inflammation and extracellular matrix-related genes in human adipocyte cultures, and IL32-silenced adipocytes showed a downregulation of inflammatory genes. Furthermore, adipocyte-conditioned media obtained from obese patients increased IL32 gene expression in human monocyte cultures, whereas the adipocyte-conditioned media from lean volunteers had no effect on IL32 mRNA levels. These findings provide evidence, for the first time, about the inflammatory and remodeling properties of IL-32 in AT, implicating this cytokine in obesity-associated comorbidities.

Maternal obesity alters brain derived neurotrophic factor (BDNF) signaling in the placenta in a sexually dimorphic manner

INTRODUCTION

Obesity is a major clinical problem in obstetrics being associated with adverse pregnancy outcomes and fetal programming. Brain derived neurotrophic factor (BDNF), a validated miR-210 target, is necessary for placental development, fetal growth, glucose metabolism, and energy homeostasis. Plasma BDNF levels are reduced in obese individuals; however, placental BDNF has yet to be studied in the context of maternal obesity. In this study, we investigated the effect of maternal obesity and sexual dimorphism on placental BDNF signaling.

METHODS

BDNF signaling was measured in placentas from lean (pre-pregnancy BMI < 25) and obese (pre-pregnancy BMI>30) women at term without medical complications that delivered via cesarean section without labor. MiRNA-210, BDNF mRNA, proBDNF, and mature BDNF were measured by RT - PCR, ELISA, and Western blot. Downstream signaling via TRKB (BDNF receptor) was measured using Western blot.

RESULTS

Maternal obesity was associated with increased miRNA-210 and decreased BDNF mRNA in placentas from female fetuses, and decreased proBDNF in placentas from male fetuses. We also identified decreased mature BDNF in placentas from male fetuses when compared to female fetuses. Mir-210 expression was negatively correlated with mature BDNF protein. TRKB phosphorylated at tyrosine 817, not tyrosine 515, was increased in placentas from obese women. Maternal obesity was associated with increased phosphorylation of MAPK p38 in placentas from male fetuses, but not phosphorylation of ERK p42/44.

DISCUSSION

BDNF regulation is complex and highly regulated. Pre-pregnancy/early maternal obesity adversely affects BDNF/TRKB signaling in the placenta in a sexually dimorphic manner. These data collectively suggest that induction of placental TRKB signaling could ameliorate the placental OB phenotype, thus improving perinatal outcome.

No differential effect of beverages sweetened with fructose, high-fructose corn syrup, or glucose on systemic or adipose tissue inflammation in normal-weight to obese adults: a randomized controlled trial

BACKGROUND

Sugar-sweetened beverage (SSB) consumption and low-grade chronic inflammation are both independently associated with type 2 diabetes and cardiovascular disease. Fructose, a major component of SSBs, may acutely trigger inflammation, which may be one link between SSB consumption and cardiometabolic disease.

OBJECTIVE

We sought to determine whether beverages sweetened with fructose, high-fructose corn syrup (HFCS), and glucose differentially influence systemic inflammation [fasting plasma C-reactive protein and interleukin-6 (IL-6) as primary endpoints] acutely and before major changes in body weight. Secondary endpoints included adipose tissue inflammation, intestinal permeability, and plasma fetuin-A as potential mechanistic links between fructose intake and low-grade inflammation.

DESIGN

We conducted a randomized, controlled, double-blind, crossover design dietary intervention (the Diet and Systemic Inflammation Study) in 24 normal-weight to obese adults without fructose malabsorption. Participants drank 4 servings/d of fructose-, glucose-, or HFCS-sweetened beverages accounting for 25% of estimated calorie requirements while consuming a standardized diet ad libitum for three 8-d periods.

RESULTS

Subjects consumed 116% of their estimated calorie requirement while drinking the beverages with no difference in total energy intake or body weight between groups as reported previously. Fasting plasma concentrations of C-reactive protein and IL-6 did not differ significantly at the end of the 3 diet periods. We did not detect a consistent differential effect of the diets on measures of adipose tissue inflammation except for adiponectin gene expression in adipose tissue (P = 0.005), which was lowest after the glucose phase. We also did not detect consistent evidence of a differential impact of these sugars on measures of intestinal permeability (lactulose:mannitol test, plasma zonulin, and plasma lipopolysaccharide-binding protein).

CONCLUSION

Excessive amounts of fructose, HFCS, and glucose from SSBs consumed over 8 d did not differentially affect low-grade chronic systemic inflammation in normal-weight to obese adults. This trial was registered at clinicaltrials.gov as NCT01424306.

Selection of Suitable Reference Genes for Quantitative Real-Time PCR Normalization in Three Types of Rat Adipose Tissue

Quantitative real-time PCR (qRT-PCR) is the most classical technique in the field of gene expression study. This method requires an appropriate reference gene to normalize mRNA levels. In this study, the expression stability of four frequently-used reference genes in epididymal white adipose tissue (eWAT), inguinal beige adipose tissue (iBeAT) and brown adipose tissue (BAT) from obese and lean rats were evaluated by geNorm, NormFinder and BestKeeper. Based on the Minimum Information for Publication of Quantitative Real-Time PCR Experiments (MIQE) guidelines, the two most stable reference genes were recommended in each type of adipose tissue. Two target genes were applied to test the stability of the reference genes. The geNorm and NormFinder results revealed that GAPDH and 36B4 exhibited the highest expression stabilities in eWAT, while 36B4 and β-actin had the highest expression stabilities in iBeAT and BAT. According to the results of the BestKeeper analysis, 36B4 was the most stable gene in eWAT, iBeAT and BAT, in terms of the coefficient of variance. In terms of the coefficient of correlation, GAPDH, 36B4 and β-actin were the most stable genes in eWAT, iBeAT and BAT, respectively. Additionally, expected results and statistical significance were obtained using a combination of two suitable reference genes for data normalization. In conclusion, 36B4 and GAPDH, in combination, are the best reference genes for eWAT, while 36B4 and β-actin are two most suitable reference genes for both iBeAT and BAT. We recommend using these reference genes accordingly.

RPL13A and EEF1A1 Are Suitable Reference Genes for qPCR during Adipocyte Differentiation of Vascular Stromal Cells from Patients with Different BMI and HOMA-IR

Real-time or quantitative PCR (qPCR) is a useful technique that requires reliable reference genes for data normalization in gene expression analysis. Adipogenesis is among the biological processes suitable for this technique. The selection of adequate reference genes is essential for qPCR gene expression analysis of human Vascular Stromal Cells (hVSCs) during their differentiation into adipocytes. To the best of our knowledge, there are no studies validating reference genes for the analyses of visceral and subcutaneous adipose tissue hVSCs from subjects with different Body Mass Index (BMI) and Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) index. The present study was undertaken to analyze this question. We first analyzed the stability of expression of five potential reference genes: CYC, GAPDH, RPL13A, EEF1A1, and 18S ribosomal RNA, during in vitro adipogenic differentiation, in samples from these types of patients. The expression of RPL13A and EEF1A1 was not affected by differentiation, thus being these genes the most stable candidates, while CYC, GAPDH, and 18S were not suitable for this sort of analysis. This work highlights that RPL13A and EEF1A1 are good candidates as reference genes for qPCR analysis of hVSCs differentiation into adipocytes from subjects with different BMI and HOMA-IR.

FGF19 and FGF21 serum concentrations in human obesity and type 2 diabetes behave differently after diet- or surgically-induced weight loss

BACKGROUND & AIMS

Fibroblast growth factor 19 (FGF19) and 21 (FGF21) have emerged as key regulators of energy homeostasis. Our aim was to analyze the impact of weight loss (WL) induced either by conventional dietary treatment (CDT) or bariatric surgery on FGF19 and FGF21 concentrations. Furthermore, the diverse effect of sleeve gastrectomy (SG) versus RYGB (Roux-en-Y gastric bypass) as two surgical procedures that affect the gastrointestinal anatomy and physiology differently was also analyzed.

METHODS

Serum concentrations of FGF19 and FGF21 were measured in 137 obese patients with different degrees of insulin resistance matched by sex, age and body adiposity and compared to 33 lean individuals. Furthermore, FGF19 and FGF21 were measured in 114 subjects before and one-year after WL induced either by CDT (n = 28), SG (n = 20) or RYGB (n = 66).

RESULTS

Circulating serum FGF19 concentrations were decreased (P < 0.01) similarly in obese patients regardless of their degree of insulin resistance, while FGF21 levels were increased in obesity (P < 0.01), being further increased in obesity-associated T2D (P < 0.01). FGF19 concentrations were increased in obese subjects after surgically-induced WL (P < 0.01), but not after WL achieved by CDT, while FGF21 levels were reduced after CDT- (P < 0.05) or SG-induced WL (P < 0.05), but not after RYGB. The change in FGF21 concentrations emerged as a significant predictor of the change in insulin resistance (HOMA) after WL.

CONCLUSIONS

Based on the circulating concentrations and their subsequent pattern of response following WL, we conclude that FGF19 levels are mainly related to body adiposity, in particular visceral adiposity, while FGF21 is mainly related to glucose homeostasis. CLINICALTRIALS.

GOV IDENTIFIER

NCT01572090.

Guanylin and uroguanylin stimulate lipolysis in human visceral adipocytes

BACKGROUND/OBJECTIVES

Uroguanylin and guanylin are secreted by intestinal epithelial cells as prohormones postprandially and act on the hypothalamus to induce satiety. The impact of obesity and obesity-associated type 2 diabetes (T2D) on proguanylin and prouroguanylin expression/secretion as well as the potential role of guanylin and uroguanylin in the control of lipolysis in humans was evaluated.

SUBJECTS/METHODS

Circulating and gastrointestinal expression of proguanylin (GUCA2A) and prouroguanylin (GUCA2B) were measured in 134 subjects. In addition, plasma proguanylin and prouroguanylin were measured before and after weight loss achieved either by Roux-en-Y gastric bypass (RYGB) (n=24) or after a conventional diet (n=15). The effect of guanylin and uroguanylin (1-100 nmol l(-1)) on lipolysis was determined in vitro in omental adipocytes.

RESULTS

Circulating concentrations of prouroguanylin, but not proguanylin, were decreased in obesity in relation to adiposity. Weight loss achieved by RYGB increased plasma proguanylin and prouroguanylin. Obese T2D individuals showed higher expression of intestinal GUCA2A as well as of the receptors of the guanylin system, GUCY2C and GUCY2D, in omental adipocytes. The incubation with guanylin and uroguanylin significantly stimulated lipolysis in differentiated omental adipocytes, as evidenced by hormone-sensitive lipase phosphorylation at Ser563, an increase in fatty acids and glycerol release together with an upregulation of several lipolysis-related genes, including AQP3, AQP7, FATP1 or CD36.

CONCLUSIONS

Both guanylin and uroguanylin trigger lipolysis in human visceral adipocytes. Given the lipolytic action of the guanylin system on visceral adipocytes, the herein reported decrease of circulating prouroguanylin concentrations in obese patients may have a role in excessive fat accumulation in obesity.