Transcriptional Analysis of FOXO1, C/EBP-α and PPAR-γ2 Genes and Their Association with Obesity-Related Insulin Resistance.

BACKGROUND: Obesity is associated with several comorbid disorders, ranging from cardiovascular diseases to insulin resistance. In this context, visceral adipose tissue (VAT) seems to have a close connection with insulin resistance. In our study, we hypothesized that the expression profile of key adipogenic genes, such as proliferator-activated receptor γ type 2 (PPAR-γ2), CCAAT/enhancer-binding protein type α (C/EBP-α), and forkhead box protein class O type 1 (FOXO1) in VAT should shed light on their association with obesity-related insulin resistance. METHODS: To test this idea, we studied the expression profile of C/EBP-α, FOXO1 and PPAR-γ2 in VAT from non-obese individuals, and low insulin (LIR-MO) and high insulin morbidly obese (HIR-MO) subjects, through a combination of RT-qPCR, co-immunoprecipitation, ELISA, Western blot analysis and EMSA assays. RESULTS: Our results show that C/EBP-α and PPAR-γ2 were down-expressed in HIR-MO individuals, while FOXO1 was overexpressed. In addition, the PPAR-γ2-RXR-α heterodimer showed weak activity and bound weakly to the putative IGFBP-2-PPRE promoter sequence in VAT from HIR-MO subjects when compared with LIR-MO individuals. CONCLUSIONS: These results show that PPAR-γ2, C/EBP-α, FOXO1 and IGFBP-2 have a close relationship with insulin resistance in VAT of morbidly obese individuals.

Role of epicardial adipose tissue NPR-C in acute coronary syndrome.

BACKGROUND AND AIMS: It has been suggested that epicardial adipose tissue (EAT) thermogenesis plays a role in coronary artery disease (CAD). Recent evidence indicates that natriuretic peptide receptors (NPRs) are critical for thermogenesis. We determined the expression and signaling of NPRs in EAT in the context of CAD progression and their association with brown fat-related genes, such as uncoupling protein 1 (UCP1) and peroxisome proliferator-activated receptor gamma coactivator alpha (PGC1α). METHODS: NPR-A, NPR-B and NPR-C mRNA and protein expression levels were analyzed in EAT and thoracic subcutaneous adipose tissue (SAT) from non-CAD (NCAD), stable CAD and acute coronary syndrome (ACS) patients. The associations of NPRs with thermogenic genes were also evaluated. RESULTS: The EAT of ACS patients showed lower NPR-C gene and protein expression levels compared with that of stable CAD or NCAD patients. NPR-C mRNA expression in EAT also decreased as the number of injured arteries rose, and correlated positively with left ventricular ejection fraction and EAT PGC1α mRNA expression. EAT PGC1α and UCP1 gene expression levels also decreased in the ACS group. Linear and logistic regression models showed associations of EAT NPR-C mRNA levels with EAT PGC1α mRNA levels and the presence of ACS. Furthermore, the EAT of ACS patients showed reduced p38 mitogen-activated protein kinase (p38 MAPK) phosphorylation levels, which correlated positively with NPR-C protein levels. CONCLUSIONS: The EAT of patients with ACS is characterized by decreased NPR-C, reduced UCP1 and PGC1α mRNA expression levels and reduced activation of the p38 MAPK pathway. The associations among the expression of EAT NPR-C and ACS, and brown fat markers suggest that NPR-C may play a role in ACS and in the regulation of EAT brown-like fat features in humans.

The Antagonist Effect of Arachidonic Acid on GLUT4 Gene Expression by Nuclear Receptor Type II Regulation.

OBJECTIVES: Obesity is a complex disease that has a strong association with diet and lifestyle. Dietary factors can influence the expression of key genes connected to insulin resistance, lipid metabolism, and adipose tissue composition. In this study, our objective was to determine gene expression and fatty acid (FA) profiles in visceral adipose tissue (VAT) from lean and morbidly obese individuals. We also aimed to study the agonist effect of dietary factors on glucose metabolism. DESIGN AND METHODS: Lean and low and high insulin resistance morbidly obese subjects (LIR-MO and HIR-MO) were included in this study. The gene expression of liver X receptor type alpha (LXR-α) and glucose transporter type 4 (GLUT4) and the FA profiles in VAT were determined. Additionally, the in vivo and in vitro agonist effects of oleic acid (OA), linoleic acid (LA), and arachidonic acid (AA) by peroxisome proliferator-activated receptor type gamma 2 (PPAR-γ2) on the activity of GLUT4 were studied. RESULTS: Our results showed a dysregulation of GLUT4 and LXR-α in VAT of morbidly obese subjects. In addition, a specific FA profile for morbidly obese individuals was found. Finally, AA was an PPAR-γ2 agonist that activates the expression of GLUT4. CONCLUSIONS: Our study suggests a dysregulation of LXR-α and GLUT4 expression in VAT of morbidly obese individuals. FA profiles in VAT could elucidate their possible role in lipolysis and adipogenesis. Finally, AA binds to PPAR-γ2 to activate the expression of GLUT4 in the HepG2 cell line, showing an alternative insulin-independent activation of GLUT4.

Overexpression of scavenger receptor and infiltration of macrophage in epicardial adipose tissue of patients with ischemic heart disease and diabetes.

BACKGROUND: Oxidized low-density lipoproteins and scavenger receptors (SRs) play an important role in the formation and development of atherosclerotic plaques. However, little is known about their presence in epicardial adipose tissue (EAT). The objective of the study was to evaluate the mRNA expression of different SRs in EAT of patients with ischemic heart disease (IHD), stratifying by diabetes status and its association with clinical and biochemical variables. METHODS: We analyzed the mRNA expression of SRs (LOX-1, MSR1, CXCL16, CD36 and CL-P1) and macrophage markers (CD68, CD11c and CD206) in EAT from 45 patients with IHD (23 with type 2 diabetes mellitus (T2DM) and 22 without T2DM) and 23 controls without IHD or T2DM. RESULTS: LOX-1, CL-P1, CD68 and CD11c mRNA expression were significantly higher in diabetic patients with IHD when compared with those without T2DM and control patients. MSR1, CXCL16, CD36 and CD206 showed no significant differences. In IHD patients, LOX-1 (OR 2.9; 95% CI 1.6-6.7; P = 0.019) and CD68 mRNA expression (OR 1.7; 95% CI 0.98-4.5; P = 0.049) were identified as independent risk factors associated with T2DM. Glucose and glycated hemoglobin were also shown to be risk factors. CONCLUSIONS: SRs mRNA expression is found in EAT. LOX-1 and CD68 and were higher in IHD patients with T2DM and were identified as a cardiovascular risk factor of T2DM. This study suggests the importance of EAT in coronary atherosclerosis among patients with T2DM.

Adipose Tissue LPL Methylation is Associated with Triglyceride Concentrations in the Metabolic Syndrome.

BACKGROUND: DNA methylation is one of the epigenetic mechanisms that regulate gene expression. DNA methylation may be modified by environmental and nutritional factors. Thus, epigenetics could potentially provide a mechanism to explain the etiology of metabolic disorders, such as metabolic syndrome (MetS). The aim of this study was to analyze the level of DNA methylation of several lipoprotein lipase (LPL)-promoter-CpG dinucleotides in a CpG island region and relate this to the gene and protein expression levels in human visceral adipose tissue (VAT) from individuals with and without MetS. METHODS: VAT samples were collected from laparoscopic surgical patients without and with MetS, and levels of LPL mRNA, LPL protein, and LPL DNA methylation were measured by qPCR, western blot, and pyrosequencing. Biochemical and anthropometric variables were analyzed. Individuals included in a subset underwent a dietary fat challenge test, and levels of postprandial triglycerides were determined. RESULTS: We found higher levels of DNA methylation in MetS patients but lower gene expression and protein levels. There was a negative association between LPL methylation and LPL gene expression. We found a positive association between LPL methylation status and abnormalities of the metabolic profile and basal and postprandial triglycerides, whereas LPL gene expression was negatively associated with these abnormalities. CONCLUSIONS: We demonstrate that LPL methylation may be influenced by the degree of metabolic disturbances and could be involved in triglyceride metabolism, promoting hypertriglyceridemia and subsequent associated disorders, such as MetS.

IGFBP-3 Interacts with the Vitamin D Receptor in Insulin Signaling Associated with Obesity in Visceral Adipose Tissue.

Adipose tissue has traditionally only been considered as an energy storage organ. Nevertheless, the importance of this tissue in systemic physiology and, especially, in systemic inflammation has been highlighted in recent years. Adipose tissue expresses proteins related to vitamin D (VD) metabolism, and it has been proposed that it can act as a VD storage tissue. The active form of VD, 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), is able to modify adipocyte and adipose tissue physiology via the VD receptor (VDR), decreasing the expression of pro-inflammatory cytokines in adipose tissue. Moreover, VD deficiency and VDR has been reported to be associated with obesity and diabetes. However, the results of the different studies are not conclusive. Insulin growth binding proteins (IGFBPs) have been identified in adipose tissue, but their roles are poorly understood. Therefore, the objective of this study was to analyze the plasma levels of VD and the gene expression of VDR in the adipose tissue of subjects with morbid obesity (MO) and with different degrees of insulin resistance (IR), as well as the functionality of direct interaction between IGFBP-3 and VDR, which could explain its inhibitory role in adipogenesis. Our results show a novel role of the VD system in the regulation and activation of IGFBP-3 in visceral adipose tissue (VAT) of patients with MO, as a new and alternative mechanism proposed in the insulin signaling associated with obesity.

Expression of epicardial adipose tissue thermogenic genes in patients with reduced and preserved ejection fraction heart failure.

Epicardial adipose tissue has been proposed to participate in the pathogenesis of heart failure. The aim of our study was to assess the expression of thermogenic genes (Uncoupling protein 1 (UCP1), peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α), and PR-domain-missing 16 (PRDM16) in epicardial adipose tissue in patients with heart failure, stablishing the difference according to left ventricular ejection fraction (reduced or preserved). Among the 75 patients in our study, 42.7% (n=32) had reduced left ventricular ejection fraction. UCP1, PGC1α and PRDM16 mRNA in EAT were significantly lower in patients with reduced left ventricular ejection fraction. Multiple regression analysis showed that age, male gender, body max index, presence of obesity, type-2-diabetes mellitus, hypertension and coronary artery disease and left ventricular ejection fraction were associated with the expression levels of UCP1, PGC1α and PRDM16 mRNA. Thermogenic genes expressions in epicardial adipose tissue (UCP1: OR 0.617, 95%CI 0.103-0.989, p=0.042; PGC1α: OR 0.416, 95%CI 0.171-0.912, p=0.031; PRDM16: OR 0.643, 95%CI 0.116-0.997, p=0.044) were showed as protective factors against the presence of heart failure with reduced left ventricular ejection fraction, and age (OR 1.643, 95%CI 1.001-3.143, p=0.026), presence of coronary artery disease (OR 6.743, 95%CI 1.932-15.301, p<0.001) and type-2-diabetes mellitus (OR 4.031, 95%CI 1.099-7.231, p<0.001) were associated as risk factors. The adequate expression of thermogenic genes has been shown as possible protective factors against heart failure with reduced ejection fraction, suggesting that a loss of functional epicardial adipose tissue brown-like features would participate in a deleterious manner on heart metabolism. Thermogenic genes could represent a future novel therapeutic target in heart failure.

Expression of Sterol Regulatory Element-Binding Proteins in epicardial adipose tissue in patients with coronary artery disease and diabetes mellitus: preliminary study.

Objectives: Sterol regulatory element-binding proteins (SREBP) genes are crucial in lipid biosynthesis and cardiovascular homeostasis. Their expression in epicardial adipose tissue (EAT) and their influence in the development of coronary artery disease (CAD) and type-2 diabetes mellitus remain to be determined. The aim of our study was to evaluate the expression of SREBP genes in EAT in patients with CAD according to diabetes status and its association with clinical and biochemical data. Methods: SREBP-1 and SREBP-2 mRNA expression levels were measured in EAT from 49 patients with CAD (26 with diabetes) and 23 controls without CAD or diabetes. Results: Both SREBPs mRNA expression were significantly higher in patients with CAD and diabetes (p<0.001) and were identified as independent cardiovascular risk factor for coronary artery disease in patients with type-2 diabetes (SREBP-1: OR 1.7, 95%CI 1.1-2.5, p=0.02; SREBP-2: OR 1.6, 95%CI 1.2-3, p=0.02) and were independently associated with the presence of multivessel CAD, left main and anterior descending artery stenosis, and higher total and LDL cholesterol levels, and lower HDL cholesterol levels, in patients with CAD and diabetes. Conclusions: SREBP genes are expressed in EAT and were higher in CAD patients with diabetes than those patients without CAD or diabetes. SREBP expression was associated as cardiovascular risk factor for the severity of CAD and the poor lipid control. In this preliminary study we suggest the importance of EAT in the lipid metabolism and cardiovascular homeostasis for coronary atherosclerosis of patients with diabetes and highlight a future novel therapeutic target.

Fibrillin 2 is upregulated in the ascending aorta of patients with bicuspid aortic valve.

OBJECTIVES: Bicuspid aortic valve (BAV) is the most prevalent congenital cardiac malformation, frequently associated with aortic dilatation (AD). The molecular mechanisms involved in AD and its aetiological link with BAV formation are poorly understood. Altered fibrillin-1 (FBN1) and metalloprotease-2, -9 (MMP2,9) protein activities have been suggested to be involved in BAV aortopathy. In addition, FBN2 participates in embryonic valve formation, but its possible involvement in BAV-associated AD has never been explored. In this report, we evaluate the expression levels of MMP2,9 and FBN1,2 in the ascending aorta of patients with normal or dilated aortas and with tricuspid aortic valve (TAV) or BAV, using appropriate tissue-specific reference genes. METHODS: Gene expression was quantified by real-time quantitative polymerase chain reaction in 52 patients, using one or three reference genes previously validated in the same patient population. RESULTS: FBN2 expression was significantly increased in the aortas of patients with BAV compared with individuals with TAV (0.178 ± 0.042 vs 0.096 ± 0.021, P = 0.015), whereas differences in FBN1 did not reach statistical significance (1.946 ± 0.228 vs 1.430 ± 0.114, P = 0.090). When four groups of samples were considered, FBN2 expression was significantly higher in patients with BAV and AD compared with patients with TAV and AD (0.164 ± 0.035 vs 0.074 ± 0.027, P = 0.040). No significant differences were found when FBN1/FBN2 ratio, and MMP2 and MMP9 expression levels were analysed. No linear relationship between aortic diameter and gene expression levels were found. CONCLUSIONS: BAV patients have an increased FBN (especially FBN2) gene expression level in the ascending aorta, irrespective of dilatation, whereas MMP expression does not change significantly. These results add a new piece of information to the pathophysiology of BAV disease and point to FBN2 as a new molecular player.

Type 2 diabetes is associated with decreased PGC1α expression in epicardial adipose tissue of patients with coronary artery disease.

BACKGROUND: Although recent studies indicate that epicardial adipose tissue expresses brown fat-like genes, such as PGC1α, UCP1 and PRDM16, the association of these genes with type 2 diabetes mellitus (DM2) in coronary artery disease (CAD) remains unknown. METHODS: PGC1α, UCP1, and PRDM16 mRNAs expression levels were measured by real-time PCR in epicardial and thoracic subcutaneous adipose tissue from 44 CAD patients (22 with DM2 [CAD-DM2] and 22 without DM2 [CAD-NDM2]) and 23 non-CAD patients (NCAD). RESULTS: The CAD-DM2 patients had significantly lower PGC1α and UCP1 expression in epicardial adipose tissue than the CAD-NDM2 and NCAD patients. However, PGC1α and UCP1 mRNA trended upward in subcutaneous adipose tissue from CAD-DM2 patients. At multiple regression analysis, age, body mass index, left ventricular ejection fraction, UCP1 expression of epicardial adipose tissue and diabetes came out to be independent predictors of PGC1α levels. Epicardial adipose tissue PGC1α expression was dependent on the number of injured coronary arteries and logistic regression analysis showed that PGC1α expression in epicardial adipose tissue could exert a protective effect against coronary lesions. CONCLUSIONS: DM2 is associated with decreased expression of PGC1α and UCP1 mRNA in epicardial adipose tissue of patients with CAD, likely reflecting a loss of brown-like fat features. Decreased expression of PGC1α in human epicardial adipose tissue is associated with higher prevalence of coronary lesions.

Papel de la leptina sérica en la gravedad de la enfermedad coronaria en pacientes con angina estable / Role of serum leptin in the severity of coronary artery disease in patients with stable angina

Fundamentos y objetivo: La leptina es una hormona plasmática que ha sido relacionada con la homeostasis cardiovascular y la aterosclerosis, pero no existen datos concluyentes sobre su asociación con la patogénesis de la enfermedad coronaria. El objetivo de este estudio fue evaluar el valor de la leptina sérica en pacientes con angina estable y su relación con la gravedad de la enfermedad coronaria. Pacientes y método: Se incluyeron 204 pacientes, 152 con angina estable (grupo con enfermedad coronaria) y 52 sin enfermedad coronaria, excluida por tomografía computarizada cardíaca (grupo control). El grupo con enfermedad coronaria fue dividido en 2 subgrupos atendiendo a la gravedad de la afectación (enfermedad monovaso o multivaso, 46 y 106 pacientes respectivamente). Los niveles de leptina sérica fueron determinados mediante Enzyme-Linked Inmunosorbent Assay. Resultados: Los niveles de leptina fueron significativamente superiores en los pacientes con enfermedad multivaso y se asociaron de forma independiente con una mayor gravedad de la enfermedad coronaria en comparación con los controles (OR 1,14; IC95% 1,03-1,27; p = 0,014) y con pacientes con enfermedad monovaso (OR 1,12; IC95% 1,01-1,25; p = 0,036). Se testó el valor diagnóstico de la leptina sérica para el diagnóstico enfermedad multivaso, obteniendo un área bajo la curva en la curva Receiver Operating Characteristic de 0,6764 (IC95% 0,5765-0,7657). Conclusiones: La leptina sérica se asoció en pacientes con angina estable con la mayor gravedad de la enfermedad coronaria, mostrando su implicación en el desarrollo de la enfermedad coronaria y como futuro objetivo terapéutico (AU)

Background and objectives: Leptin is a plasmatic peptide hormone that has been related to cardiovascular homeostasis and atherosclerosis but much is still unknown about its relationship with coronary artery disease. The aim of this study was to evaluate the value of serum leptin in patients with stable angina and its relationship with the severity of coronary disease. Patients and methods: 204 patients, 152 with stable angina (coronary artery disease group) and 52 without coronary disease excluded by cardiac computerized tomography (control group) were included. The coronary artery disease group was divided into 2 subgroups according to severity of coronary disease (single or multivessel disease, 46 and 106 patients, respectively). Serum leptin levels were determined by Enzyme-Linked InmunoSorbent Assay. Results: Leptin levels were significantly higher in patients with multivessel disease and were independently associated with a greater severity of coronary artery disease when compared with controls (OR 1.14; 95%CI: 1.03-1.27; p = 0.014) and with patients with single vessel disease (OR 1.12; 95%CI: 1.01-1.25; p = 0.036). Serum leptin was tested as a diagnostic marker of multivessel disease with an area under the curve obtained from Receiver Operating Characteristics of 0.6764 (95%CI 0.5765-0.7657). Conclusions: Serum leptin levels were associated in patients with stable angina with the severity of coronary artery disease, suggesting its value in the development of coronary disease and as a future therapeutic target (AU)

[Role of serum leptin in the severity of coronary artery disease in patients with stable angina]. / Papel de la leptina sérica en la gravedad de la enfermedad coronaria en pacientes con angina estable.

BACKGROUND AND OBJECTIVES: Leptin is a plasmatic peptide hormone that has been related to cardiovascular homeostasis and atherosclerosis but much is still unknown about its relationship with coronary artery disease. The aim of this study was to evaluate the value of serum leptin in patients with stable angina and its relationship with the severity of coronary disease. PATIENTS AND METHODS: 204 patients, 152 with stable angina (coronary artery disease group) and 52 without coronary disease excluded by cardiac computerized tomography (control group) were included. The coronary artery disease group was divided into 2 subgroups according to severity of coronary disease (single or multivessel disease, 46 and 106 patients, respectively). Serum leptin levels were determined by Enzyme-Linked InmunoSorbent Assay. RESULTS: Leptin levels were significantly higher in patients with multivessel disease and were independently associated with a greater severity of coronary artery disease when compared with controls (OR 1.14; 95%CI: 1.03-1.27; p=0.014) and with patients with single vessel disease (OR 1.12; 95%CI: 1.01-1.25; p=0.036). Serum leptin was tested as a diagnostic marker of multivessel disease with an area under the curve obtained from Receiver Operating Characteristics of 0.6764 (95%CI 0.5765-0.7657). CONCLUSIONS: Serum leptin levels were associated in patients with stable angina with the severity of coronary artery disease, suggesting its value in the development of coronary disease and as a future therapeutic target.

Serum 25-hydroxyvitamin D and adipose tissue vitamin D receptor gene expression: relationship with obesity and type 2 diabetes.

CONTEXT: The relationship between 25-hydroxyvitamin D [25(OH)D] and obesity and type 2 diabetes is not completely understood. Vitamin D receptor (VDR) expression in adipose tissue (AT) is related to obesity and might be regulated by 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. OBJECTIVE: To analyze serum 25(OH)D and VDR gene expression in AT according to body mass index (BMI) and glycemic status and the effect of 1,25(OH)2D3 on AT according to BMI. DESIGN AND PATIENTS: Two cohorts were studied: 1) 118 subjects classified according to their BMI (lean, overweight, obese, or morbidly obese [MO]) and their glycemic status (normoglycemic [NG] and prediabetic and diabetic [P&D]); and 2) 30 obese subjects (BMI > 30 kg/m(2)) classified as NG and P&D. VDR gene expression was analyzed during preadipocyte differentiation and in vitro stimulation with 1,25(OH)2D3 of AT explants from donors with different BMI values. SETTING: University Hospital. MAIN OUTCOME MEASURES: Serum 25(OH)D, parathyroid hormone (PTH), and AT VDR gene expression. RESULTS: 25(OH)D levels were lower in P&D than NG subjects, significantly so in the lean and MO groups (P < .05). 25(OH)D levels correlated negatively with homeostasis model of assessment for insulin resistance (HOMA-IR) (r = -0.200; P = .032) and glucose (r = -0.295; P = .001), but not with BMI. VDR gene expression was higher in MO than in the other BMI groups (P < .05). 1,25(OH)2D3 increased VDR gene expression in AT from obese patients (P < .05) but not from lean subjects. CONCLUSIONS: 25(OH)D levels are diminished in P&D compared to NG subjects, independently of BMI, and are closely related to glucose metabolism variables, suggesting that vitamin D deficiency is associated more with carbohydrate metabolism than with obesity. Moreover, AT has a different response to 1,25(OH)2D3 depending on the degree of obesity.

Computational and biological evaluation of N-octadecyl-N'-propylsulfamide, a selective PPARα agonist structurally related to N-acylethanolamines.

To further understand the pharmacological properties of N-oleoylethanolamine (OEA), a naturally occurring lipid that activates peroxisome proliferator-activated receptor alpha (PPARα), we designed sulfamoyl analogs based on its structure. Among the compounds tested, N-octadecyl-N'-propylsulfamide (CC7) was selected for functional comparison with OEA. The performed studies include the following computational and biological approaches: 1) molecular docking analyses; 2) molecular biology studies with PPARα; 3) pharmacological studies on feeding behavior and visceral analgesia. For the docking studies, we compared OEA and CC7 data with crystallization data obtained with the reference PPARα agonist GW409544. OEA and CC7 interacted with the ligand-binding domain of PPARα in a similar manner to GW409544. Both compounds produced similar transcriptional activation by in vitro assays, including the GST pull-down assay and reporter gene analysis. In addition, CC7 and OEA induced the mRNA expression of CPT1a in HpeG2 cells through PPARα and the induction was avoided with PPARα-specific siRNA. In vivo studies in rats showed that OEA and CC7 had anorectic and antiobesity activity and induced both lipopenia and decreases in hepatic fat content. However, different effects were observed when measuring visceral pain; OEA produced visceral analgesia whereas CC7 showed no effects. These results suggest that OEA activity on the PPARα receptor (e.g., lipid metabolism and feeding behavior) may be dissociated from other actions at alternative targets (e.g., pain) because other non cannabimimetic ligands that interact with PPARα, such as CC7, do not reproduce the full spectrum of the pharmacological activity of OEA. These results provide new opportunities for the development of specific PPARα-activating drugs focused on sulfamide derivatives with a long alkyl chain for the treatment of metabolic dysfunction.

The retinoic acid receptor-related orphan nuclear receptor γ1 (RORγ1): a novel player determinant of insulin sensitivity in morbid obesity.

The orphan nuclear receptors (ONRs), retinoic acid receptor-related orphan receptor γ-1 (RORγ1) and peroxisome proliferator-activated receptor γ-2 (PPARγ2), are central mediators controlling adipocyte (AD) differentiation. Through their distinct tissue distribution and specific target gene activation, ONRs control diverse aspects of fatty acid metabolism and insulin sensitivity. Adding further complexity, obesity begets resistance to insulin signals and can ultimately result in diabetes. In this study, we investigate whether there are differences in the RORγ1 and PPARγ2 expression in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) from morbid obesity (MO) individuals either insulin resistant (high-IR MO) or insulin sensitivity (low-IR MO). Our results indicate for the first time in human the RORγ1 mRNA and protein expression levels and activation with coactivator, such as peroxisome proliferator-activated receptor γ coactivator 1-α (PGC-1α) were higher in the VAT from high-IR MO. In contrast, PPARγ2 expression and activation were higher in the VAT from low-IR MO. In this way, we have also found a positive association between RORγ1 mRNA and protein expression with many components of metabolic syndrome, with a strong dependence of insulin and HOMA(IR) index in VAT, but not in SAT. Our data suggest that RORγ1 may be added to the growing list of nuclear receptors in adipose tissue use to modulate the insulin resistance associated to the obesity. Measurement of RORγ1 and PPARγ2 in adipose tissue might be useful for evaluating the outcomes of various clinical interventions for obesity-related diabetes type II.

Stearoyl-CoA desaturase-1 is associated with insulin resistance in morbidly obese subjects.

Animal studies have revealed the association between stearoyl-CoA desaturase 1 (SCD1) and obesity and insulin resistance. However, only a few studies have been undertaken in humans. We studied SCD1 in visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) from morbidly obese patients and their association with insulin resistance, sterol regulatory element binding protein-1 (SREBP-1) and ATPase p97, proteins involved in SCD1 synthesis and degradation. The insulin resistance was calculated in 40 morbidly obese patients and 11 overweight controls. Measurements were made of VAT and SAT SCD1, SREBP-1 and ATPase p97 mRNA expression and protein levels. VAT and SAT SCD1 mRNA expression levels in the morbidly obese patients were significantly lower than in the controls (P = 0.006), whereas SCD1 protein levels were significantly higher (P < 0.001). In the morbidly obese patients, the VAT SCD1 protein levels were decreased in patients with higher insulin resistance (P = 0.007). However, SAT SCD1 protein levels were increased in morbidly obese patients with higher insulin resistance (P < 0.05). Multiple linear regressions in the morbidly obese patients showed that the variable associated with the SCD1 protein levels in VAT was insulin resistance, and the variables associated with SCD1 protein levels in SAT were body mass index (BMI) and ATPase p97. In conclusion, these data suggest that the regulation of SCD1 is altered in individuals with morbid obesity and that the SCD1 protein has a different regulation in the two adipose tissues, as well as being closely linked to the degree of insulin resistance.

PPARgamma expression after a high-fat meal is associated with plasma superoxide dismutase activity in morbidly obese persons.

Peroxisome proliferator-activated receptor-gamma (PPARgamma) may play a protective role in the regulation of vascular function, partly mediated by its effects on superoxide dismutase (SOD). The aim of this study was to determine the association between PPARgamma expression in peripheral blood mononuclear cells (PBMCs) and SOD activity in morbidly obese persons with varying degrees of insulin resistance (IR). We studied in 10 morbidly obese persons (five with no IR and five with high IR) the effect of a high-fat meal on the plasma activity of various antioxidant enzymes and the mRNA expression of PPARgamma in PBMC. The high-fat meal resulted in a significant decrease in plasma SOD activity, glutathione reductase (GSH-Rd) activity, and mRNA expression of PPARgamma only in the group of morbidly obese persons with high IR. PPARgamma expression after the high-fat meal correlated with the IR levels (r = -0.803, P = 0.009) and the plasma SOD activity (r = 0.903, P = 0.001). Likewise, the reduction in PPARgamma expression correlated with the increase in free fatty acids (FFA) (r = 0.733, P = 0.016). In conclusion, the decreased expression of PPARgamma in PBMC in morbidly obese persons after a high-fat meal was associated with the state of IR, the plasma SOD activity, and the changes in the concentration of FFA.

VEGF gene expression in adult human thymus fat: a correlative study with hypoxic induced factor and cyclooxygenase-2.

UNLABELLED: It is well known that the adult human thymus degenerates into fat tissue; however, it has never been considered as a potential source of angiogenic factors. Recently, we have described that this fat (TAT) produces angiogenic factors and induces human endothelial cell proliferation and migration, indicating its potential angiogenic properties. DESIGN: Adult thymus fat and subcutaneous adipose tissue specimens were obtained from 28 patients undergoing cardiac surgery, making this tissue readily available as a prime source of adipose tissue. We focused our investigation on determining VEGF gene expression and characterizing the different genes, mediators of inflammation and adipogenesis, and which are known to play a relevant role in angiogenesis regulation. RESULTS: We found that VEGF-A was the isoform most expressed in TAT. This expression was accompanied by an upregulation of HIF-1alpha, COX-2 and HO-1 proteins, and by increased HIF-1 DNA binding activity, compared to SAT. Furthermore, we observed that TAT contains a high percentage of mature adipocytes, 0.25% of macrophage cells, 15% of endothelial cells and a very low percentage of thymocyte cells, suggesting the cellular variability of TAT, which could explain the differences in gene expression observed in TAT. Subsequently, we showed that the expression of genes known as adipogenic mediators, including PPARgamma1/gamma2, FABP-4 and adiponectin was similar in both TAT and SAT. Moreover the expression of these latter genes presented a significantly positive correlation with VEGF, suggesting the potential association between VEGF and the generation of adipose tissue in adult thymus. CONCLUSION: Here we suggest that this fat has a potential angiogenic function related to ongoing adipogenesis, which substitutes immune functions within the adult thymus. The expression of VEGF seems to be associated with COX-2, HO-1 and adipogenesis related genes, suggesting the importance that this new fat has acquired in research in relation to adipogenesis and angiogenesis.