Senescence-associated ß-galactosidase in subcutaneous adipose tissue associates with altered glycaemic status and truncal fat in severe obesity.

AIM/HYPOTHESIS: Altered adipose tissue secretory profile contributes to insulin resistance and type 2 diabetes in obesity. Preclinical studies have identified senescent cells as a cellular source of proinflammatory factors in adipose tissue of obese mice. In humans, potential links with obesity comorbidities are poorly defined. Here, we investigated adipose tissue senescent status and relationships with metabolic complications in human obesity. METHODS: The study includes a prospective cohort of 227 individuals with severe obesity. A photometric method was used to quantify senescence-associated ß-galactosidase (SA-ß-gal) activity in paired subcutaneous and omental adipose tissue biopsies obtained during gastric surgery. Gene and secretory profiling was performed in adipose tissue biopsies and in human primary pre-adipocytes in the presence or absence of senolytic drugs targeting senescent cells. Participants were phenotyped for anthropometric and bioclinical variables, metabolic complications and gastric surgery-induced improvement to address relationships with adipose tissue SA-ß-gal. RESULTS: SA-ß-gal activity was sevenfold higher in subcutaneous than in omental adipose tissue and not associated with BMI or chronological age. Several factors, including insulin-like growth factor binding protein 3 (IGFBP3), plasminogen activator inhibitor 1 (PAI1), C-C motif chemokine ligand 2 (CCL2) and IL-6, were upregulated in subcutaneous adipose tissue in relation with SA-ß-gal (p for linear trend across tertiles <0.05) and in pre-adipocytes cultured with inflammatory macrophage conditioned media. Senolytic treatment reduced SA-ß-gal staining and normalised these alterations. In the whole population, subcutaneous adipose tissue SA-ß-gal activity was positively associated with serum leptin, markers of insulin resistance and increased trunk fat mass. Metabolic complications, including type 2 diabetes and dyslipidaemia, were more prevalent in patients with high levels of SA-ß-gal, but improved with bariatric surgery whatever the initial adipose tissue senescent status. CONCLUSIONS/INTERPRETATION: This study highlights a phenotype of senescence in adipose tissue of severely obese individuals, which characterises prominently subcutaneous fat depots. Subcutaneous adipose tissue senescence is significantly linked to altered glucose metabolism and body fat distribution. Elimination of senescent cells through senolytic treatment could alleviate metabolic complications in severely obese people. Graphical abstract.

Subcutaneous adipose tissue imaging of human obesity reveals two types of adipocyte membranes: Insulin-responsive and -nonresponsive.

In adipose tissue, resistance to insulin's ability to increase glucose uptake can be induced by multiple factors, including obesity. Impaired insulin action may take place at different spatial loci at the cellular or subcellular level. To begin to understand the spatial response to insulin in human subcutaneous adipose tissue (hSAT), we developed a quantitative imaging method for activation of a major signaling node in the glucoregulatory insulin signaling pathway. After treatment with insulin or control media, biopsied tissues were immunostained for Akt phosphorylation at Thr-308/9 (pAkt) and then imaged by confocal fluorescence microscopy automated to collect a large grid of high resolution fields. In hSAT from 40 men and women with obesity, substantial heterogeneity of pAkt densities in adipocyte membranes were quantified in each image mosaic using a spatial unit of at least twice the size of the point spread function. Statistical analysis of the distribution of pAkt spatial units was best fit as the weighted sum of two separate distributions, corresponding to either a low or high pAkt density. A "high pAkt fraction" metric was calculated from the fraction of high pAkt distributed units over the total units. Importantly, upon insulin stimulation, tissues from the same biopsy showed either a minimal or a substantial change in the high pAkt fraction. Further supporting a two-state response to insulin stimulation, subjects with similar insulin sensitivity indices are also segregated into either of two clusters identified by the amount of membrane-localized pAkt.

Somatic PIK3CA mutations are present in multiple tissues of facial infiltrating lipomatosis.

BackgroundFacial infiltrating lipomatosis (FIL) is a congenital disorder that causes overgrowth of one side of the face. The purpose of this study was to determine whether PIK3CA mutations are present in tissues outside of the subcutaneous adipose.MethodsFIL tissues from three patients were dissected to enrich for cells from skin, subcutaneous tissue, orbicularis oris muscle, buccal fat, zygomatic bone, and mucosal neuroma. Endothelial cells within the affected tissue also were enriched using CD31 microbeads. Laser capture microdissection on formalin-fixed paraffin-embedded histologic sections was performed to collect specific cell types. DNA was extracted from each tissue and cell type, and measured for the abundance of mutant PIK3CA alleles using droplet digital PCR.ResultsWe detected mutant PIK3CA alleles in every tissue and cell type tested from each overgrown face; frequencies ranged from 1.5 to 53%. There were fewer mutant endothelial cells compared with nonendothelial cells, and the stromal cell compartment had the highest frequency of mutant cells in each tissue.ConclusionsPIK3CA mutations are not restricted to a single tissue or cell type in FIL. Overgrowth in this condition is likely due to the mutation arising in a cell that contributes to several different facial structures during embryogenesis.

Metalloproteinase 2 and 9 Activity Increase in Epicardial Adipose Tissue of Patients with Coronary Artery Disease.

BACKGROUND: Epicardial adipose tissue (EAT) is a visceral adipose tissue (AT) surrounding and infiltrating myocardium and coronary arteries. Increased EAT may represent a chronic inflammatory injury and a link with coronary artery disease (CAD). Metalloproteinases (MMPs) are involved in expansion of AT. OBJECTIVE: To evaluate MMP-2 and -9 behaviour in EAT from CAD patients. METHODS: In EAT and subcutaneous AT (SAT) from patients undergoing coronary artery bypass graft (CABG, n=26) or valve replacement (No CABG, n=18), MMP-2 and -9 activity and localization, inflammatory cells and vascular endothelial growth factor (VEGF) levels were determined. RESULTS: In EAT from CABG, MMP-2 and -9 activity was increased compared with No CABG (p=0.041 and p=0.027, respectively) and compared with SAT (p=0.005 and p=0.048, respectively). In CABG patients EAT showed higher infiltration of macrophages and T lymphocytes than SAT (p=0.01 and p=0.002, respectively). In No CABG patients no sign of cellular retention was observed in EAT or SAT. Vascular density was higher in EAT from CABG than No CABG (p=0.015) and it was directly correlated with MMP-2 (p=0.006) and MMP-9 (p=0.02). VEGF levels in EAT were directly associated with MMP-2 (p=0.016). CONCLUSION: In EAT from CABG patients the increase of MMP-2 and -9 activity and the presence of inflammatory cells would be partially responsible for extracellular matrix (ECM) remodeling and major vascular density necessary for EAT expansion. Improved knowledge of EAT behaviour may allow to identify new therapeutic targets for the treatment of CAD.

Sirt1 decreased adipose inflammation by interacting with Akt2 and inhibiting mTOR/S6K1 pathway in mice.

Sirtuin type 1 (Sirt1) and protein kinase B (Akt2) are associated with development of obesity and inflammation, but the molecular mechanisms of Sirt1 and Akt2 interaction on adipose inflammation remain unclear. To explore these mechanisms, a mouse model was used. Mice were fed with a high-fat diet (HFD) for 8 weeks, with interventions of resveratrol (RES) or nicotinamide (NAM) during the last 15 days. The HFD reduced Sirt1 mRNA in adipose tissue and elevated interleukin-6 (IL-6) expression. RES reduced the adipose tissue weight, increased the Sirt1 mRNA level, and reduced both mRNA and protein levels of IL-6, MCP-1, inducible nitric oxide synthase, and TNF-α by inhibiting phosphorylation of Akt2 in adipose tissue. Additionally, macrophage type I marker genes were reduced while macrophage type II marker genes were elevated by RES addition. Moreover, activation of Akt2 signal by using insulin significantly blunted the inhibitory effect of RES on adipose inflammation. Immunoprecipitation assay demonstrated that RES enhances the protein-protein interaction between Sirt1 and Akt2, but NAM inhibits this interaction. Furthermore, Sirt1 significantly reduced the levels of raptor and inactivated mammalian target of rapamycin (mTOR)C1 signal by interacting with Akt2, and confirmed that RES attenuated adipose inflammation by inhibiting the mTOR/S6K1 pathway via rapamycin.

Macrophage Infiltration into Subcutaneous Adipose Tissue is Associated with Local Levels of 11BHSD1.

The present study aimed to evaluate the infiltration of macrophages in form of crown-line structures (CLS) in subcutaneous adipose tissue (SAT) of obese individuals, and to investigate the effect of these on both metabolic parameters and adipose tissue 11-beta-hydroxysteroid dehydrogenase type 1 (11BHSD1) enzyme levels. A total of 53 obese (10 men, 43 woman) enrolled in the study. Body mass index (BMI), waist circumference (WC), hip circumfrence, and systolic (SBP) and diastolic blood pressures (DBP) of all subjects were recorded. Insulin resistance was determined using the homeostasis model assessment (HOMA). The concentration of SAT, tumor necrosis factor (TNF)-α, interleukin (IL)-6, 11BHSD1 were performed by enzyme-linked immunosorbent assay (ELISA) method. The infiltration of macrophages in form of CLS in adipose tissue were determined using cell-specific stains against CD68. There was no significant difference between the CLS+group and the CLS- group in terms of age, gender, BMI, WC, waist-to-hip circumference ratio (WHR), SBP and DBP levels. Fasting plasma glucose (FPG), HOMA-IR, insulin and SAT TNF-α levels were higher in the CLS+group compared to the CLS- group. FPG and SAT TNF-α levels were significantly higher in participants with high CLS density compared to participants with low density CLS. SAT 11BHSD1 levels was significant higher in the CLS+group compare to the CLS- group and in the high CLS density group compared to the low density group. In conclusion, the infiltration of macrophages in the form of CLS in SAT is associated with increased 11BHSD1 levels. It may be an important mechanism in the development of metabolic disorders.

Steroid sulfatase activity in subcutaneous and visceral adipose tissue: a comparison between pre- and postmenopausal women.

OBJECTIVE: Adipose tissue is an important extragonadal site for steroid hormone biosynthesis. After menopause, estrogens are synthesized exclusively in peripheral tissues from circulating steroid precursors, of which the most abundant is dehydroepiandrosterone sulfate (DHEAS). Our aim was to study activity of steroid sulfatase, an enzyme hydrolyzing DHEAS, and expression of steroid-converting enzyme genes in subcutaneous and visceral adipose tissue derived from pre- and postmenopausal women. DESIGN: Serum and paired abdominal subcutaneous and visceral adipose tissue samples were obtained from 18 premenopausal and seven postmenopausal women undergoing elective surgery for non-malignant reasons in Helsinki University Central Hospital. METHODS: To assess steroid sulfatase activity, radiolabeled DHEAS was incubated in the presence of adipose tissue homogenate and the liberated dehydroepiandrosterone (DHEA) was measured. Gene mRNA expressions were analyzed by quantitative RT-PCR. Serum DHEAS, DHEA, and estrogen concentrations were determined by liquid chromatography-tandem mass spectrometry. RESULTS: Steroid sulfatase activity was higher in postmenopausal compared to premenopausal women in subcutaneous (median 379 vs 257 pmol/kg tissue per hour; P=0.006) and visceral (545 vs 360 pmol/kg per hour; P=0.004) adipose tissue. Visceral fat showed higher sulfatase activity than subcutaneous fat in premenopausal (P=0.035) and all (P=0.010) women. The mRNA expression levels of two estradiol-producing enzymes, aromatase and 17ß-hydroxysteroid dehydrogenase type 12, were higher in postmenopausal than in premenopausal subcutaneous adipose tissue. CONCLUSIONS: Steroid sulfatase activity in adipose tissue was higher in postmenopausal than in premenopausal women suggesting that DHEAS, derived from the circulation, could be more efficiently utilized in postmenopausal adipose tissue for the formation of biologically active sex hormones.

[Effect of free fatty acids on CYP19A1 (aromatase) gene expression in human adipose tissue stromal vascular fraction cells].

Aromatase plays an important role in the estrogen biosynthesis. Its gen (CYP19A1) is expressed in preadipocytes (stromal vascular fraction, SVF) of adipose tissue. Estrogens are found to be protective for metabolism homeostasis, and cardiovascular system. Disturbed dietary and endogenous fatty acids (FAs) turnover is responsible for development of metabolic syndrome and it complications. Aim of the work was to investigate the effect of physiological concentrations of acids: arachidonic (AA), oleic (OA), palmitynoic (PA) and eikozapentaenoic (EPA) on CYP19A1 expression in differentiating human SVF, able to form adipocytes as well as endothelial cells. Material and Methods: Human (n=38 healthy woman) SVF cells were isolated from subcutaneous adipose tissue harvested intrasurgery. SVF cells were incubated in proadipogenic or angiogenic media to obtain adipocytes (Adipo-SVF) or endothelial (Angio-SVF) cells (confirmed by microarray). Changes in the CYP19A1 expression induced by 24hs incubation in the presence of FAs (10 ­ 30 µM )were monitored by the Real time PCR (qRT -PCR). Results: The aromatase gene expression correlated positively with BMI of patients, but only in group of obese or overweight women. The negative correlation was found in the group of young, slim women. The highest expression of aromatase was found in the fresh, not differentiated SVF. In differentiating to endothelial cells (Angio - SVF) OA inhibited (p=0.008), when n-3 polyunsaturated AA activated (p=0.003) the CYP19A1 gene expression. In differentiating to preadipocytes (Adipo-SVF) AA significantly (p=0.031) inhibited CYP19A1 expression. Conclusion: The changes in the aromatase gene expression in differentiating SVF has been confirmed. The different effect of the dietary FA (OA vs. AA) on the aromatase gene expression argue for the role of the locally formed proangiogenic estrogens.

Improved Insulin Sensitivity 3 Months After RYGB Surgery Is Associated With Increased Subcutaneous Adipose Tissue AMPK Activity and Decreased Oxidative Stress.

Morbidly obese individuals are predisposed to a wide range of disorders, including type 2 diabetes, atherosclerotic cardiovascular disease, fatty liver disease, and certain cancers. Remarkably, all of these disorders can be improved or prevented by Roux-en-Y gastric bypass (RYGB) surgery. We have reported that decreased AMPK activity, together with increased oxidative stress and inflammation in adipose tissue, is associated with insulin resistance in morbidly obese bariatric surgery patients. In the current study, we assessed how these parameters are affected by RYGB surgery. Eleven patients (average age of 46 ± 4 years) were studied immediately prior to surgery and 3 months postoperatively. We measured subcutaneous adipose tissue AMPK phosphorylation (threonine 172, an index of its activation), malonyl-CoA content, protein carbonylation (a marker of oxidative stress), plasma adiponectin, and mRNA expression of several inflammatory cytokines. After surgery, AMPK activity increased 3.5-fold and oxidative stress decreased by 50% in subcutaneous adipose tissue. In addition, malonyl-CoA levels were reduced by 80%. Furthermore, patients had improvements in their BMI and insulin sensitivity (HOMA) and had increased circulating high-molecular weight adiponectin and decreased fasting plasma insulin levels. In contrast, the expression of inflammatory markers in subcutaneous adipose tissue was unchanged postoperatively, although plasma CRP was diminished by 50%.

Glitazones inhibit human monoamine oxidase but their anti-inflammatory actions are not mediated by VAP-1/semicarbazide-sensitive amine oxidase inhibition.

Glitazones are peroxisome proliferator-activated receptor gamma (PPARγ) agonists widely used as antidiabetic drugs also known as thiazolidinediones. Most of them exert other effects such as anti-inflammatory actions via mechanisms supposed to be independent from PPARγ activation (e.g., decreased plasma monocyte chemoattractant protein-1 (MCP-1) levels). Recently, pioglitazone has been shown to inhibit the B form of monoamine oxidase (MAO) in mouse, while rosiglitazone and troglitazone were described as non-covalent inhibitors of both human MAO A and MAO B. Since molecules interacting with MAO might also inhibit semicarbazide-sensitive amine oxidase (SSAO), known as vascular adhesion protein-1 (VAP-1), and since VAP-1/SSAO inhibitors exhibit anti-inflammatory activity, our aim was to elucidate whether VAP-1/SSAO inhibition could be a mechanism involved in the anti-inflammatory behaviour of glitazones. To this aim, MAO and SSAO activities were measured in human subcutaneous adipose tissue biopsies obtained from overweight women undergoing plastic surgery. The production of hydrogen peroxide, an end-product of amine oxidase activity, was determined in tissue homogenates using a fluorometric method. The oxidation of 1 mM tyramine was inhibited by pargyline and almost resistant to semicarbazide, therefore predominantly MAO-dependent. Rosiglitazone was more potent than pioglitazone in inhibiting tyramine oxidation. By contrast, benzylamine oxidation was only abolished by semicarbazide: hence SSAO-mediated. Pioglitazone hampered SSAO activity only when tested at 1 mM while rosiglitazone was inefficient. However, rosiglitazone exhibited anti-inflammatory activity in human adipocytes by limiting MCP-1 expression. Our observations rule out any involvement of VAP-1/SSAO inhibition and subsequent limitation of leukocyte extravasation in the anti-inflammatory action of glitazones.

Association of nicotinamide-N-methyltransferase mRNA expression in human adipose tissue and the plasma concentration of its product, 1-methylnicotinamide, with insulin resistance.

AIMS/HYPOTHESIS: Nicotinamide-N-methyltransferase (NNMT) was recently shown to be upregulated in mouse models of insulin resistance and obesity. So far, it is unknown whether NNMT is regulated in human disease. We have explored the hypothesis that white adipose tissue (WAT) NNMT expression and plasma 1-methylnicotinamide (MNA) concentration are increased in human insulin resistance and type 2 diabetes. METHODS: NNMT expression and plasma MNA were analysed in three groups of individuals: (1) 199 patients undergoing abdominal surgery; (2) 60 individuals on a 12-week exercise programme and (3) 55 patients on a two-step bariatric surgery programme. RESULTS: Patients with manifest type 2 diabetes have a significantly (approximately twofold) higher NNMT expression both in omental and subcutaneous WAT compared with controls. Notably, plasma MNA correlated significantly with WAT NNMT expression in patients with type 2 diabetes (women, r = 0.59, p < 0.001; men, r = 0.61, p < 0.001) but not in healthy control individuals. In insulin-resistant individuals, there was an inverse correlation between insulin sensitivity and plasma MNA (r = 0.44, p = 0.01) or adipose tissue NNMT mRNA (r = 0.64, p < 0.001). The latter association was confirmed in a second cohort (n = 60, r = 0.78, p < 0.001). Interventions improving insulin sensitivity--exercise and bariatric surgery--were associated with a significant (p < 0.001) reduction in WAT NNMT expression. Bariatric surgery was also associated with a significant decrease in plasma MNA. CONCLUSIONS/INTERPRETATION: We demonstrate that WAT NNMT expression is regulated in human insulin resistance and type 2 diabetes and that plasma MNA correlates with increased tissue NNMT expression and the degree of insulin resistance, making it a potential biomarker for loss of insulin sensitivity.

Free fatty acids, lipopolysaccharide and IL-1α induce adipocyte manganese superoxide dismutase which is increased in visceral adipose tissues of obese rodents.

Excess fat storage in adipocytes is associated with increased generation of reactive oxygen species (ROS) and impaired activity of antioxidant mechanisms. Manganese superoxide dismutase (MnSOD) is a mitochondrial enzyme involved in detoxification of ROS, and objective of the current study is to analyze expression and regulation of MnSOD in obesity. MnSOD is increased in visceral but not subcutaneous fat depots of rodents kept on high fat diets (HFD) and ob/ob mice. MnSOD is elevated in visceral adipocytes of fat fed mice and exposure of differentiating 3T3-L1 cells to lipopolysaccharide, IL-1α, saturated, monounsaturated and polyunsaturated free fatty acids (FFA) upregulates its level. FFA do not alter cytochrome oxidase 4 arguing against overall induction of mitochondrial enzymes. Upregulation of MnSOD in fat loaded cells is not mediated by IL-6, TNF or sterol regulatory element binding protein 2 which are induced in these cells. MnSOD is similarly abundant in perirenal fat of Zucker diabetic rats and non-diabetic animals with similar body weight and glucose has no effect on MnSOD in 3T3-L1 cells. To evaluate whether MnSOD affects adipocyte fat storage, MnSOD was knocked-down in adipocytes for the last three days of differentiation and in mature adipocytes. Knock-down of MnSOD does neither alter lipid storage nor viability of these cells. Heme oxygenase-1 which is induced upon oxidative stress is not altered while antioxidative capacity of the cells is modestly reduced. Current data show that inflammation and excess triglyceride storage raise adipocyte MnSOD which is induced in epididymal adipocytes in obesity.

Adipose dipeptidyl peptidase-4 and obesity: correlation with insulin resistance and depot-specific release from adipose tissue in vivo and in vitro.

OBJECTIVE: To study expression of the recently identified adipokine dipeptidyl peptidase-4 (DPP4) in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) of patients with various BMIs and insulin sensitivities, as well as to assess circulating DPP4 in relation to obesity and insulin sensitivity. RESEARCH DESIGN AND METHODS: DPP4 expression was measured in SAT and VAT from 196 subjects with a wide range of BMIs and insulin sensitivities. DPP4 release was measured ex vivo in paired biopsies from SAT and VAT as well as in vivo from SAT of lean and obese patients. Circulating DPP4 was measured in insulin-sensitive and insulin-resistant BMI-matched obese patients. RESULTS: DPP4 expression was positively correlated with BMI in both SAT and VAT, with VAT consistently displaying higher expression than SAT. Ex vivo release of DPP4 from adipose tissue explants was higher in VAT than in SAT in both lean and obese patients, with obese patients displaying higher DPP4 release than lean controls. Net release of DPP4 from adipose tissue was also demonstrated in vivo with greater release in obese subjects than in lean subjects and in women than in men. Insulin-sensitive obese patients had significantly lower circulating DPP4 than did obesity-matched insulin-resistant patients. In this experiment, DPP4 positively correlated with the amount of VAT, adipocyte size, and adipose tissue inflammation. CONCLUSIONS: DPP4, a novel adipokine, has a higher release from VAT that is particularly pronounced in obese and insulin-resistant patients. Our data suggest that DPP4 may be a marker for visceral obesity, insulin resistance, and the metabolic syndrome.

The expression of 11ß-HSDs, GR, and H6PDH in subcutaneous adipose tissue from polycystic ovary syndrome subjects.

The aim of the work was to investigate the expression of 11ß-hydroxysteroid dehydrogenase (11ß-HSD) type 1 and 2, hexose-6-phosphate dehydrogenase (H6PDH), and glucocorticoids receptor (GR) mRNA in subcutaneous adipose tissue (SAT) from obese women with or without polycystic ovary syndrome (PCOS), and the association between their expression and the adipocytokines' concentration. Sixteen women with PCOS (group P) and 18 age- and BMI-matched control women (group C) were enrolled for the study. Subcutaneous adipose tissue was collected from the abdomen. The genes' expression was detected by real-time PCR, and the adipocytokines' concentration was measured by ELISA. Peripheral insulin sensitivity was assessed by homeostatic assessment model of insulin resistance (HOMA-IR). ß-cell function was assessed by homeostasis model assessment of ß-cell function (HOMA-IS). The expression of 11ß-HSD1 mRNA was significantly higher in PCOS subjects (p<0.05) than controls; there was no difference for the expression of 11ß-HSD2, GR, and H6PDH mRNA between the 2 groups. The stepwise multiple linear regression analysis showed that the mRNA level of 11ß-HSD1 was positively correlated to the concentration of the serum tumor necrosis factor-alpha (TNF-α). Expression of 11ß-HSD1 mRNA was increased in the SAT from the women with PCOS, which may contribute to the increased local active glucocorticoids (cortisol), and subsequently affects the secretion of the local adipose tissue.

Differences between men and women in the regulation of adipose 11ß-HSD1 and in its association with adiposity and insulin resistance.

This study explored sex differences in 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) activity and gene expression in isolated adipocytes and adipose tissue (AT), obtained via subcutaneous biopsies from non-diabetic subjects [58 M, 64 F; age 48.3 ± 15.3 years, body mass index (BMI) 27.2 ± 3.9 kg/m²]. Relationships with adiposity and insulin resistance (IR) were addressed. Males exhibited higher 11ß-HSD1 activity in adipocytes than females, but there was no such difference for AT. In both men and women, adipocyte 11ß-HSD1 activity correlated positively with BMI, waist circumference, % body fat, adipocyte size and with serum glucose, triglycerides and low-density lipoprotein:high-density lipoprotein (LDL:HDL) ratio. Positive correlations with insulin, HOMA-IR and haemoglobin A1c (HbA1c) and a negative correlation with HDL-cholesterol were significant only in males. Conversely, 11ß-HSD1 activity in AT correlated with several markers of IR and adiposity in females but not in males, but the opposite pattern was found with respect to 11ß-HSD1 mRNA expression. This study suggests that there are sex differences in 11ß-HSD1 regulation and in its associations with markers of obesity and IR.

Modulation of double-stranded RNA-activated protein kinase in insulin sensitive tissues of obese humans.

OBJECTIVE: The double-stranded RNA-dependent protein kinase (PKR) was recently implicated in regulating molecular integration of nutrient- and pathogen-sensing pathways in obese mice. However, its modulation in human tissues in situations of insulin resistance has not been investigated. The present study was performed to first determine the tissue expression and phosphorylation levels of PKR in the liver, muscle, and adipose tissue in obese humans, and also the modulation of this protein in the adipose tissue of obese patients after bariatric surgery. DESIGN AND METHODS: Eleven obese subjects who were scheduled to undergo Roux-en-Y Gastric Bypass Procedure participated in this study. Nine apparently healthy lean subjects as a control group were also included. RESULTS: Our data show that PKR is activated in liver, muscle, and adipose tissue of obese humans and, after bariatric surgery, there is a clear reduction in PKR activation accompanied by a decrease in protein kinase-like endoplasmic reticulum kinase, c-Jun N-terminal kinase, inhibitor of kappa ß kinase, and insulin receptor substrate-1 serine 312 phosphorylation in subcutaneous adipose tissue from these patients. CONCLUSION: Thus, it is proposed that PKR is an important mediator of obesity-induced insulin resistance and a potential target for the therapy.

Regulation of 11ß-HSD1 expression during adipose tissue expansion by hypoxia through different activities of NF-κB and HIF-1α.

11ß-Hydroxysteroid dehydrogenase type 1 (11ß-HSD1) is involved in the pathogenesis of type 2 diabetes by generating active glucocorticoids (cortisol and corticosterone) that are strong inhibitors of angiogenesis. However, the mechanism of 11ß-HSD1 gene expression and its relationship to adipose angiogenesis are largely unknown. To address this issue, we examined 11ß-HSD1 expression in visceral and subcutaneous adipose tissue (AT) of diet-induced obese (DIO) mice during weight gain and investigated the gene regulation by hypoxia in vitro. 11ß-HSD1 mRNA was reduced in the adipose tissues during weight gain in DIO mice, and the reduction was associated with an elevated expression of angiogenic factors. In vitro, 11ß-HSD1 expression was induced in mRNA and protein by hypoxia. Of the two transcription factors activated by hypoxia, the nuclear factor-κB (NF-κB) enhanced but the hypoxia inducible factor-1α (HIF-1α) reduced 11ß-HSD1 expression. 11ß-HSD1 expression was elevated by NF-κB in epididymal fat of aP2-p65 mice. The hypoxia-induced 11ß-HSD1 expression was attenuated by NF-κB inactivation in p65-deficient cells but enhanced by HIF-1 inactivation in HIF-1α-null cells. These data suggest that 11ß-HSD1 expression is upregulated by NF-κB and downregulated by HIF-1α. During AT expansion in DIO mice, the reduction of 11ß-HSD1 expression may reflect a dominant HIF-1α activity in the adipose tissue. This study suggests that NF-κB may mediate the inflammatory cytokine signal to upregulate 11ß-HSD1 expression.

Activities of lipogenic enzymes in subcutaneous adipose tissue are not increased in patients with chronic kidney failure.

INTRODUCTION: Since renal replacement therapy has started to be a routine procedure in chronic kidney disease (CKD), patients no longer die of end-stage renal disease (ESRD). Today, patients with CKD live longer and the most important causes of morbidity and mortality in this group are cardiovascular events. Lipid abnormalities, such as hypertriglyceridemia (HT), are an important factor of high cardiovascular risk in this group. It is known that HT is partially caused by inhibition of lipolysis, but it is also postulated that increased lipogenesis is another cause of HT. Previous studies performed in our center has provided evidence that lipogenesis is increased in the animal model of ESRD.  OBJECTIVES: The aim of this study was to investigate the activities of lipogenic enzymes in the subcutaneous white adipose tissue in patients with CKD. PATIENTS AND METHODS: The study was performed on 36 patients (17 women and 19 men). Patients with ESRD were divided into 2 groups: patients on conservative treatment in the prehemodialysis period (pre­HD group, n = 18) and patients on maintenance hemodialysis (HD group, n = 18). The control group consisted of 22 patients without ESRD. The activities of lipogenic enzymes in the subcutaneous white adipose tissue (fatty acid synthase, adenosine triphosphate citrate lyase, malic enzyme, glucose­6­phosphate dehydrogenase, and 6­phosphogluconate dehydrogenase) were assessed by spectrophotometry.  RESULTS: There were no statistically significant differences in the activities of lipogenic enzymes in a fat tissue sample between patients with ESRD and the control group. CONCLUSIONS: The results did not confirm increased lipogenesis in patients with ESRD.