Search

There has been an explosion of interest in the signaling capacity of energy metabolites. A prime example is the Krebs cycle substrate succinate, an archetypal respiratory substrate with functions beyond energy production as an intracellular and extracellular signaling molecule. Long associated with inflammation, emerging evidence supports a key role for succinate in metabolic processes relating to energy management. As the natural ligand for SUCNR1, a G protein-coupled receptor, succinate is akin to hormones and likely functions as a reporter of metabolism and stress. In this review, we reconcile new and old observations to outline a regulatory role for succinate in metabolic homeostasis. We highlight the importance of the succinate-SUCNR1 axis in metabolic diseases as an integrator of macrophage immune response, and we discuss new metabolic functions recently ascribed to succinate in specific tissues. Because circulating succinate has emerged as a promising biomarker in chronic metabolic diseases, a better understanding of the physiopathological role of the succinate-SUCNR1 axis in metabolism might open new avenues for clinical use in patients with obesity or diabetes.

Purpose Recent studies point to adipose-derived stem cells (ASCs) as a link between obesity and cancer. We aimed to determine whether survivin, which is highly secreted by ASCs from subjects with obesity, might drive a pro-tumoral phenotype in macrophages. Methods The effect of ASC conditioned medium on the macrophage phenotype was assessed by expression studies. Survivin intracellular localization and internalization were examined by subcellular fractionation and immunofluorescence, respectively. Loss- and gain-of-function studies were performed using adenoviral vectors, and gene expression patterns, migration and invasion capacities of cancer cells were examined. Heterotypic cultures of ASCs, macrophages and cancer cells were established to mimic the tumor microenvironment. Survivin-blocking experiments were used to determine the impact of survivin on both macrophages and cancer cells. Immunohistochemical analysis of survivin was performed in macrophages from ascitic fluids of cancer patients and healthy controls. Results We found that obese-derived ASCs induced a phenotypic switch in macrophages characterized by the expression of both pro- and anti-inflammatory markers. Macrophages were found to internalize extracellular survivin, generating hybrid macrophages with a tumor-associated phenotype that included secretion of survivin. Exogenous expression of survivin in macrophages generated a similar phenotype and enhanced the malignant characteristics of cancer cells by a mechanism dependent on survivin phosphorylation at threonine 34. Survivin secreted by both ASCs from subjects with obesity and tumor-associated macrophages synergistically boosted the malignancy of cancer cells. Importantly, survivin was mainly detected in ascites-associated macrophages from patients with a malignant diagnosis. Conclusion Our data indicate that survivin may serve as a molecular link between obesity and cancer and as a novel marker for tumor-associated macrophages.

Background: Succinate is produced by both host and microbiota, with a key role in the interplay of immunity and metabolism and an emerging role as a biomarker for infammatory and metabolic disorders in middle-aged adults. The relationship between plasma succinate levels and cardiovascular disease (CVD) risk in young adults is unknown. Methods: Cross-sectional study in 100 (65% women) individuals aged 18–25 years from the ACTIvating Brown Adipose Tissue through Exercise (ACTIBATE) study cohort. CVD risk factors, body composition, dietary intake, basal metabolic rate, and cardiorespiratory ftness were assessed by routine methods. Plasma succinate was measured with an enzyme-based assay. Brown adipose tissue (BAT) was evaluated by positron emission tomography, and circulating oxylipins were assessed by targeted metabolomics. Fecal microbiota composition was analyzed in a sub-sample. Results: Individuals with higher succinate levels had higher levels of visceral adipose tissue (VAT) mass (+42.5%), tri‑ glycerides (+63.9%), C-reactive protein (+124.2%), diastolic blood pressure (+5.5%), and pro-infammatory omega-6 oxylipins than individuals with lower succinate levels. Succinate levels were also higher in metabolically unhealthy individuals than in healthy overweight/obese peers. Succinate levels were not associated with BAT volume or activity or with fecal microbiota composition and diversity. Conclusions: Plasma succinate levels are linked to a specifc pro-infammatory omega-6 signature pattern and higher VAT levels, and seem to refect the cardiovascular status of young adults., Spanish Ministry of Economy and Competitiveness via Retos de la Sociedad (DEP2016-79512-R to JRR and RTI2018-093919-B to SFV), European Regional Development Funds (ERDF), Spanish Ministry of Education (FPU16/02828, FPU16/05159, FPU17/01523 and FPU19/01609), University of Granada Plan Propio de Investigación 2016-Excellence actions–Unit of Excellence on Exercise and Health (UCEES), Junta de Andalucía, Consejería de Conocimiento, Investigación y Universidades (ERDF: ref. SOMM17/6107/UGR), The Spanish Ministry of Science and Innovation (PI20/00095 to VCM and PI20/00338 to JV) co-fnanced by the European Regional Development Fund (ERDF), Ramón y Cajal program (RYC2019026490-I) from the Spanish Ministry of Science and Innovation, co-fnanced by the ERDF, y Fundación Bancaria Caixa d’Estalvis i Pensions de Barcelona (HR20-00051 to S.F.-V.), The Netherlands CardioVascular Research Initiative: ‘the Dutch Heart Foundation, Dutch Federation of University Medical Centers, The Netherlands Organization for Health Research and Development and the Royal Netherlands Academy of Sciences’ (CVON2017-20 GENIUS-2) to PCNR, Chinese Scholarship Council (CSC, No. 201707060012) to XD, Miguel Servet tenure-track program (CP10/00438 and CPII16/00008) from the Fondo de Investigación Sanitaria, co-fnanced by the ERDF, Fundación Alfonso Martin Escudero

Adipose-derived mesenchymal stem cells (ASCs) are a promising option for the treatment of obesity and its metabolic co-morbidities. Despite the recent identification of brown adipose tissue (BAT) as a potential target in the management of obesity, the use of ASCs isolated from BAT as a therapy for patients with obesity has not yet been explored. Metabolic activation of BAT has been shown to have not only thermogenic effects, but it also triggers the secretion of factors that confer protection against obesity. Herein, we isolated and characterized ASCs from the visceral adipose tissue surrounding a pheochromocytoma (IB-hASCs), a model of inducible BAT in humans. We then compared the anti-obesity properties of IB-hASCs and human ASCs isolated from visceral white adipose tissue (W-hASCs) in a murine model of diet-induced obesity. We found that both ASC therapies mitigated the metabolic abnormalities of obesity to a similar extent, including reducing weight gain and improving glucose tolerance. However, infusion of IB-hASCs was superior to W-hASCs in suppressing lipogenic and inflammatory markers, as well as preserving insulin secretion. Our findings provide evidence for the metabolic benefits of visceral ASC infusion and support further studies on IB-hASCs as a therapeutic option for obesity-related comorbidities.

Succinate is a signaling metabolite sensed extracellularly by succinate receptor 1 (SUNCR1). The accumulation of succinate in macrophages is known to activate a pro-inflammatory program; however, the contribution of SUCNR1 to macrophage phenotype and function has remained unclear. Here we found that activation of SUCNR1 had a critical role in the anti-inflammatory responses in macrophages. Myeloid-specific deficiency in SUCNR1 promoted a local pro-inflammatory phenotype, disrupted glucose homeostasis in mice fed a normal chow diet, exacerbated the metabolic consequences of diet-induced obesity and impaired adipose-tissue browning in response to cold exposure. Activation of SUCNR1 promoted an anti-inflammatory phenotype in macrophages and boosted the response of these cells to type 2 cytokines, including interleukin-4. Succinate decreased the expression of inflammatory markers in adipose tissue from lean human subjects but not that from obese subjects, who had lower expression of SUCNR1 in adipose-tissue-resident macrophages. Our findings highlight the importance of succinate-SUCNR1 signaling in determining macrophage polarization and assign a role to succinate in limiting inflammation., This study was supported by grants from the Spanish Ministry of Science, Innovation and Universities (PI14/00228 and PI17/01503 to J.V., SAF2015-65019-R to S.F.-V., SAF2014-56819-R and SAF2015-71878-REDT to A.C., BFU2016-78951-R to G.M.-M., PI15/00143 to C.S. and PI15/01562 to A.M., BFU2015-70454-REDT and BFU2017-90578-REDT to S.F.-V. and G.M.-M.) co-financed by the European Regional Development Fund (ERDF). The Spanish Biomedical Research Center in Diabetes and Associated Metabolic Disorders (CIBERDEM) (CB07708/0012) is an initiative of the Instituto de Salud Carlos III. N.K. is recipient of a predoctoral fellowship from MINECO, Spain (FPI, BES-2016-077745). C.S. acknowledges support from the ‘Ramón y Cajal’ program from MINECO (RYC2013-13186) and S.F.-V. the Miguel Servet tenure-track program (CP10/00438 and CPII16/00008) from the Fondo de Investigación Sanitaria, co-financed by the ERDF.

The study was supported by grants from the Instituto de Salud Carlos III (PI14/00228, PI17/0153 and PI20/00338 to J.V.), Ministerio de Ciencia e Innovación (RTI2018- 093919-B-I00 to S.F.-V. and PID2019-105969GB-I00 to A.M) and Generalitat Valenciana (PROMETEO/2018/A/133 to A.M), co-financed by the European Regional Development Fund. The Spanish Biomedical Research Center in Diabetes and Associated Metabolic Disorders (CB07708/0012) is an initiative of the Instituto de Salud Carlos III. S.FV. acknowledges the Miguel Servet tenure-track program (CP10/00438 and CPII16/00008) from Fondo de Investigación Sanitaria.

OBJECTIVE To determine the potential use of baseline circulating succinate to predict type 2 diabetes remission after bariatric surgery. RESEARCH DESIGN AND METHODS Forty-five obese patients with diabetes were randomly assigned to Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG), or laparoscopic greater curvature plication. Anthropometric parameters were evaluated, and a complete biochemical analysis including circulating serum succinate concentrations was performed at baseline and 1 year after surgery. The results were externally validated in a second cohort including 88 obese patients with diabetes assigned to RYGB or SG based on clinical criteria. RESULTS Succinate baseline concentrations were an independent predictor of diabetes remission after bariatric surgery. Patients achieving remission after 1 year had lower levels of baseline succinate (47.8 [37.6–64.6] µmol/L vs. 64.1 [52.5–82.9] µmol/L; P = 0.018). Moreover, succinate concentrations were significantly decreased 1 year after surgery (58.9 [46.4–82.4] µmol/L vs. 46.0 [35.8–65.3] µmol/L, P = 0.005). In multivariate analysis, the best logistic regression model showed that baseline succinate (odds ratio [OR] 11.3, P = 0.031) and the type of surgery (OR 26.4, P = 0.010) were independently associated with remission. The C-statistic for this model was 0.899 (95% CI 0.809–0.989) in the derivation cohort, which significantly improved the prediction of remission compared with current available scores, and 0.729 (95% CI 0.612–0.846) in the validation cohort. Interestingly, patients had a different response to the type of surgery according to baseline succinate, with significant differences in remission rates. CONCLUSIONS Circulating succinate is reduced after bariatric surgery. Baseline succinate levels have predictive value for diabetes remission independently of previously described presurgical factors and improve upon the current available scores to predict remission.

Background A functional population of adipocyte precursors, termed adipose-derived stromal/stem cells (ASCs), is crucial for proper adipose tissue (AT) expansion, lipid handling, and prevention of lipotoxicity in response to chronic positive energy balance. We previously showed that obese human subjects contain a dysfunctional pool of ASCs. Elucidation of the mechanisms underlying abnormal ASC function might lead to therapeutic interventions for prevention of lipotoxicity by improving the adipogenic capacity of ASCs. Methods Using epigenome-wide association studies, we explored the impact of obesity on the methylation signature of human ASCs and their differentiated counterparts. Mitochondrial phenotyping of lean and obese ASCs was performed. TBX15 loss- and gain-of-function experiments were carried out and western blotting and electron microscopy studies of mitochondria were performed in white AT biopsies from lean and obese individuals. Results We found that DNA methylation in adipocyte precursors is significantly modified by the obese environment, and adipogenesis, inflammation, and immunosuppression were the most affected pathways. Also, we identified TBX15 as one of the most differentially hypomethylated genes in obese ASCs, and genetic experiments revealed that TBX15 is a regulator of mitochondrial mass in obese adipocytes. Accordingly, morphological analysis of AT from obese subjects showed an alteration of the mitochondrial network, with changes in mitochondrial shape and number. Conclusions We identified a DNA methylation signature in adipocyte precursors associated with obesity, which has a significant impact on the metabolic phenotype of mature adipocytes.

Adipose tissue-derived stem cells (ASCs) are proposed as an alternative stem cell source to bone marrow-derived cells for immune cell therapy. However, microenvironmental factors may impact the functionality of this population in human adipose tissue (AT). We hypothesized that the fat depot in addition to the donor phenotype controls the immunomodulatory capacity of ASCs. Focusing on obesity and type 2 diabetes (T2D) as metabolic disorders that might affect the immune response of ASCs, we compared the inflammatory response of ASCs from subcutaneous and visceral AT of age-matched donors (lean n = 4, body mass index [BMI] 21.98 ± 1.9; obese n = 4 BMI 33.1 ± 2.1 and T2D n = 4 BMI 35.3 ± 1.5). Obese and particularly T2D-derived ASCs showed increased expression of inflammatory markers, activation of NLRP3 inflammasome and higher migration, invasion and phagocytosis capacities than those derived from lean donors. Remarkably, ASCs derived from obese and T2D subjects exhibited a reduction in typical immunosuppressive activities attributed to stem cells. Accordingly, obese and T2D-ASCs were less effective in suppressing lymphocyte proliferation, activating the M2 macrophage phenotype, and in increasing TGF-β1 secretion, than lean-derived ASCs. Treatment of lean hASCs with interleukin (IL)-1β mimicked the dysfunctional immune behavior of obese and T2D hASCs. Conversely, combined treatment with IL1RA and TGF-β1 reverted the phenotype of obese- and T2D-ASCs. These data indicate that the donor metabolic phenotype compromises the immunomodulatory properties of ASCs. These results are relevant not only for understanding the physiology of ASCs in terms of cell-based therapies but also for their role as key regulators of the immune response. Video Highlight: https://youtu.be/ceWOIIZd7Jo

Succinate is a signaling metabolite sensed extracellularly by succinate receptor 1 (SUNCR1). The accumulation of succinate in macrophages is known to activate a pro-inflammatory program; however, the contribution of SUCNR1 to macrophage phenotype and function has remained unclear. Here we found that activation of SUCNR1 had a critical role in the anti-inflammatory responses in macrophages. Myeloid-specific deficiency in SUCNR1 promoted a local pro-inflammatory phenotype, disrupted glucose homeostasis in mice fed a normal chow diet, exacerbated the metabolic consequences of diet-induced obesity and impaired adipose-tissue browning in response to cold exposure. Activation of SUCNR1 promoted an anti-inflammatory phenotype in macrophages and boosted the response of these cells to type 2 cytokines, including interleukin-4. Succinate decreased the expression of inflammatory markers in adipose tissue from lean human subjects but not that from obese subjects, who had lower expression of SUCNR1 in adipose-tissue-resident macrophages. Our findings highlight the importance of succinate-SUCNR1 signaling in determining macrophage polarization and assign a role to succinate in limiting inflammation.

Objective\ud \ud β-secretase/β-site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1) is a key enzyme involved in Alzheimer's disease that has recently been implicated in insulin-independent glucose uptake in myotubes. However, it is presently unknown whether BACE1 and the product of its activity, soluble APPβ (sAPPβ), contribute to lipid-induced inflammation and insulin resistance in skeletal muscle cells.\ud \ud \ud \ud Materials/Methods\ud \ud Studies were conducted in mouse C2C12 myotubes, skeletal muscle from Bace1−/−mice and mice treated with sAPPβ and adipose tissue and plasma from obese and type 2 diabetic patients.\ud \ud \ud \ud Results\ud \ud We show that BACE1 inhibition or knockdown attenuates palmitate-induced endoplasmic reticulum (ER) stress, inflammation, and insulin resistance and prevents the reduction in Peroxisome Proliferator-Activated Receptor γ Co-activator 1α (PGC-1α) and fatty acid oxidation caused by palmitate in myotubes. The effects of palmitate on ER stress, inflammation, insulin resistance, PGC-1α down-regulation, and fatty acid oxidation were mimicked by soluble APPβ in vitro. BACE1 expression was increased in subcutaneous adipose tissue of obese and type 2 diabetic patients and this was accompanied by a decrease in PGC-1α mRNA levels and by an increase in sAPPβ plasma levels of obese type 2 diabetic patients compared to obese non-diabetic subjects. Acute sAPPβ administration to mice reduced PGC-1α levels and increased inflammation in skeletal muscle and decreased insulin sensitivity.\ud \ud \ud \ud Conclusions\ud \ud Collectively, these findings indicate that the BACE1 product sAPPβ is a key determinant in ER stress, inflammation and insulin resistance in skeletal muscle and gluconeogenesis in liver.

To study whether FGF21 was present in cord blood and explore its relationship with maternal variables and postnatal growth. The study included 157 pregnant women at the beginning of the third trimester; 79 with gestational diabetes (GDM), 78 with normal glucose tolerance (NGT), and their offspring. Glucose metabolism was assessed by oral glucose tolerance test. Insulin resistance was assessed by homeostasis model assessment index–insulin resistance (HOMA-IR). FGF21 was determined in maternal plasma drawn at recruitment and in cord blood obtained at delivery. Offspring weight and height was assessed at birth and at 12, 24 and 48 months. Maternal FGF21 was higher in gestational diabetes than in the normal glucose-tolerant group, whereas similar cord blood FGF21 levels were observed in both groups. Lower cord blood FGF21 was strongly positively correlated with maternal circulating levels. This relationship was independent of mother’s prepregnancy body mass index (BMI), glucose levels and HOMA-IR. Although maternal FGF21 levels were correlated with prepregnancy BMI and HOMA-IR index, no relationship was observed between FGF21 and birth weight. However, cord blood FGF21 levels were correlated with BMI Zeta Score at 12 and 24 months, and this relationship became stronger when only the NGT group was analyzed. FGF21 is present in human cord blood, and its levels are closely correlated with maternal levels. The association observed between cord blood FGF21 and postnatal BMI may suggest a potential role during intrauterine life that may influence future metabolic imbalance.

Adipose tissue (AT) has a central role in obesity-related metabolic imbalance through the dysregulated production of cytokines and adipokines. In addition to its known risk for cardiovascular disease and diabetes, obesity is also a major risk for cancer. We investigated the impact of obesity for the expression of survivin, an antiapoptotic protein upregulated by adipokines and a diagnostic biomarker of tumor onset and recurrence. In a cross-sectional study of 111 subjects classified by body mass index, circulating levels of survivin and gene expression in subcutaneous AT were significantly higher in obese patients and positively correlated with leptin. Within AT, survivin was primarily detected in human adipocyte-derived stem cells (hASCs), the adipocyte precursors that determine AT expansion. Remarkably, survivin expression was significantly higher in hASCs isolated from obese patients that from lean controls and was increased by proinflammatory M1 macrophage soluble factors including IL-1β. Analysis of survivin expression in hASCs revealed a complex regulation including epigenetic modifications and protein stability. Surprisingly, obese hASCs showed survivin promoter hypermethylation that correlated with a significant decrease in its mRNA levels. Nonetheless, a lower level of mir-203, which inhibits survivin protein translation, and higher protein stability, was found in obese hASCs compared with their lean counterparts. We discovered that survivin levels determine the susceptibility of hASCs to apoptotic stimuli (including leptin and hypoxia). Accordingly, hASCs from an obese setting were protected from apoptosis. Collectively, these data shed new light on the molecular mechanisms governing AT expansion in obesity through promotion of hASCs that are resistant to apoptosis, and point to survivin as a potential new molecular player in the communication between AT and tumor cells. Thus, inhibition of apoptosis targeting survivin might represent an effective strategy for both obesity and cancer therapy.

Background: The primary purpose of this study was to investigate the significance of pretreatment glycemic parameters in the prognosis of head and neck squamous cell carcinoma (HNSCC). Methods: Plasma samples of 71 patients with untreated HNSCC were obtained at the time of diagnosis. The prognostic value of fasting insulin, glucose, glycosylated hemoglobin levels, and the homeostatic model of risk assessment-insulin resistance (HOMA-IR) was evaluated toward disease-free survival. Results: High HOMA-IR levels were associated with poor disease-free survival in intermediate-advanced stage tumors. Kaplan-Meier curves showed lower disease-free survival rates in patients with high HOMA-IR than in patients with low levels. In patients with intermediate-advanced stage tumors, multivariate analysis revealed that those with an HOMA-IR > 2.974 presented a 2.7 times higher risk of poor outcome (95% confidence interval [CI] 1.023-7.341; P = .045). Conclusion: The HOMA-IR is independently associated with disease-free survival in patients with HNSCC. We found an optimal HOMA-IR cutoff value for disease-free survival in patients with intermediate- advanced HNSCC.

Objective For a long time Aquaporin-7 has been the only aquaporin associated with the adipose tissue, and its dysregulation has been linked to the underlying mechanisms of obesity. However, the presence of alternative glycerol channels within the adipose tissue has been postulated, which has prompted us to the search of alternate glycerol transport routes in adipocytes. In view of this, it is hypothesized that Aquaporin-11 (AQP11) would have a role in adipocyte cell biology. Methods The expression, the localization and the function of human AQP11 (hAQP11) in cultured differentiated adipocytes were investigated. Results Gene expression analysis revealed the presence of AQP11 in both subcutaneous and visceral human mature adipocytes. It is found that hAQP11 is primarily located intracellularly in human adipocytes and partially colocalizes with perilipin, pointing towards AQP11 preferential location in the vicinity of lipid droplets. Overexpression of hAQP11 in 3T3-L1 adipocytes enabled to validate its function as a water channel and reveal its glycerol permeation activity. Conclusions hAQP11 permeates both water and glycerol, localizing in the vicinity of lipid droplets in human adipocytes.

The aim of this study was to investigate the relationship between advanced glycation end products (AGEs) and arterial stiffness (AS) in subjects with type 1 diabetes without clinical cardiovascular events. A set of 68 patients with type 1 diabetes and 68 age- and sex-matched healthy subjects were evaluated. AGEs were assessed using serum concentrations ofN-carboxy-methyl-lysine (CML) and using skin autofluorescence. AS was assessed by aortic pulse wave velocity (aPWV), using applanation tonometry. Patients with type 1 diabetes had higher serum concentrations of CML (1.18 vs 0.96 μg/ml;P=0.008) and higher levels of skin autofluorescence (2.10 vs 1.70;Pr=0.370;P=0.003). No association was found between CML and aPWV. Skin autofluorescence was independently and significantly associated with aPWV in subjects with type 1 diabetes (β=0.380;P

In the article cited above, the clinical trial number was mistakenly given as NCT1410475, clinicaltrials.gov. …

Visceral fat is strongly associated with insulin resistance. Obesity-associated adipose tissue inflammation and inflammatory cytokine production are considered key mediators of insulin signaling inhibition. TWEAK is a relatively new member of the TNF cytokine superfamily, which can exist as full length membrane-associated (mTWEAK) and soluble (sTWEAK) isoforms. Although TWEAK has been shown to have important functions in chronic inflammatory diseases its physiological role in adipose tissue remains unresolved. In this study, we explore the molecular mechanisms involved in the modulation of TNF-α-induced effects on insulin sensitivity by sTWEAK in a human visceral adipose cell line and also in primary human adipocytes obtained from visceral fat depots. Our data reveal that sTWEAK ameliorates TNF-α-induced insulin resistance on glucose uptake, GLUT4 translocation and insulin signaling without affecting other metabolic effects of TNF-α such as lipolysis or apoptotis. Co-immunoprecipitation experiments in adipose cells revealed that pretreatment with sTWEAK specifically inhibits TRAF2 association with TNFR1, but not with TNFR2, which mediates insulin resistance. However, sTWEAK does not affect other downstream molecules activated by TNF-α, such as TAK1. Rather, sTWEAK abolishes the stimulatory effect of TNF-α on JNK1/2, which is directly involved in the development of insulin resistance. This is associated with an increase in PP2A activity upon sTWEAK treatment. Silencing of the PP2A catalytic subunit gene overcomes the dephosphorylation effect of sTWEAK on JNK1/2, pointing to PP2A as a relevant mediator of sTWEAK-induced JNK inactivation. Overall, our data reveal a protective role of TWEAK in glucose homeostasis and identify PP2A as a new driver in the modulation of TNF-α signaling by sTWEAK.

Recent advances have demonstrated that the adipose tissue plays a central role in regulating overall energy balance. Obesity results from a chronic deregulation of energy balance, with energy intake exceeding energy expenditure. Recently, new mechanisms that control the obesity phenotype such as the equilibrium between white and brown adipose tissue function has been identified. In this context, it is becoming increasingly clear that in addition to cellular growth, AMP-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) also regulate lipid metabolism and adipogenesis. Here, we review recent advances in the understanding of the molecular mechanisms involved in white and brown differentiation programs focusing on AMPK and mTOR signaling pathways, which may play differential roles in white adipose tissue and brown adipose tissue development. In view of the worldwide epidemic of obesity and its associated metabolic disorders such as insulin resistance and type 2 diabetes, targeting these kinases may represent a potential approach for reducing adiposity and improving obesity-related diseases. © 2013 IUBMB Life, 65(7):572-583, 2013.

Leptin, adiponectin and IL18 are adipokines related with obesity, insulin resistance and dyslipidemia in the general population. Treated HIV-1-infected patients with lipodystrophy may develop insulin resistance and proatherogenic dyslipidemia. We assessed the relationship between plasma adipokine levels, adipokine genetics, lipodystrophy and metabolic disturbances. Plasma leptin, adiponectin and IL18 levels were assessed in 446 individuals: 282 HIV-1-infected patients treated with antiretroviral drugs (132 with lipodystrophy and 150 without) and 164 uninfected controls (UC). The LEP2410A > G, LEPRQ223R, ADIPQ276G > T, ADIPOR2-Intron5A > G and IL18-607C > A polymorphisms were validated by sequencing. Leptin levels were higher in UC than in HIV-1-infected, either with or without lipodystrophy (p < 0.001 for both comparisons) and were lower in patients with lipodystrophy compared with those without lipodystrophy (p = 0.006). In patients with lipodystrophy, leptin had a positive correlation with insulin and with HOMA-IR. Adiponectin levels were non-significantly different in UC and HIV-1-infected patients. Patients with lipodystrophy had lower adiponectin levels than non-lipodystrophy subjects (p < 0.001). In patients with lipodystrophy, adiponectin was negatively correlated with insulin, HOMA-IR and triglycerides. Plasma IL18 levels were higher in HIV-1-infected patients compared with UC (p < 0.001), and no differences were found according to the presence of lipodystrophy. In patients with lipodystrophy there was a negative correlation between IL18 levels and LDLc. Genetic analyses indicated no significant associations with lipodystrophy nor with insulin resistance or with lipid abnormalities. In conclusion, HIV-1-infected patients have reduced plasma leptin levels. This reduction is magnified in patients with lipodystrophy whose adiponectin levels were lower than that of non-lipodystrophy subjects. Plasma IL18 levels are increased in infected patients irrespective of the presence of lipodystrophy. The polymorphisms assessed are not associated with lipodystrophy or metabolic disturbances in treated HIV-1-infected patients. (C) 2012 Elsevier Ltd. All rights reserved.

Objectives Treated HIV-1-infected patients with lipodystrophy often develop insulin resistance and proatherogenic dyslipidaemia. Zinc alpha-2 glycoprotein (ZAG) is a recently characterized adipokine which has been shown to be involved in the development of obesity and metabolic syndrome in uninfected subjects. We assessed the relationship between circulating ZAG levels and metabolic derangements in HIV-1-infected patients receiving antiretroviral drugs. Methods Plasma ZAG levels were assessed in 222 individuals: 166 HIV-1-infected patients treated with antiretroviral drugs (77 with lipodystrophy and 89 without lipodystrophy) and 56 uninfected controls. Plasma ZAG levels were assessed by enzyme-linked immunosorbent assay (ELISA) and were correlated with fat distribution abnormalities and metabolic parameters. Results HIV-1-infected patients had lower plasma ZAG levels compared with uninfected controls (P

OBJECTIVE To analyze the relationship between maternal adiponectin (mAdiponectin) and cord blood adiponectin (cbAdiponectin) multimeric forms (high molecular weight [HMW], medium molecular weight [MMW], and low molecular weight [LMW]) in a cohort of gestational diabetes mellitus (GDM) and normal glucose–tolerant (NGT) pregnant women. RESEARCH DESIGN AND METHODS A total of 212 women with a singleton pregnancy, 132 with NGT and 80 with GDM, and their offspring were studied. Maternal blood was obtained in the early third trimester and cord blood was obtained at delivery. Total adiponectin and the multimeric forms of adiponectin were determined in cord blood and maternal serum. Spearman rank correlation and stepwise linear correlation analysis were used to assess the relationship between cbAdiponectin levels and clinical and analytical parameters. RESULTS No differences in cbAdiponectin concentration or its multimeric forms were observed in the offspring of diabetic mothers compared with NGT mothers. The HMW-to-total adiponectin ratio was higher in cord blood than in maternal serum, whereas the MMW- and LMW-to-total adiponectin ratio was lower. Cord blood total and HMW adiponectin levels were positively correlated with birth weight and the ponderal index (PI), whereas cord blood MMW adiponectin was negatively correlated with the PI. In addition, cbAdiponectin and its multimeric forms were correlated with mAdiponectin concentrations. In the multivariate analysis, maternal multimeric forms of adiponectin emerged as independent predictors of cbAdiponectin, its multimers, and their distribution. CONCLUSIONS cbAdiponectin concentrations are independently related to mAdiponectin levels and unrelated to the diagnosis of GDM. Maternal multimeric forms of adiponectin are independent predictors of the concentrations of cbAdiponectin and its multimeric forms at delivery.

AQP7 is considered to be the sole adipose glycerol channel, and its regulation is crucial for glycemia control.In this work, we aimed to further characterize AQP7 in human adipose tissue in obesity and type 2 diabetes (T2D): 1) to assess AQP7 expression levels in paired abdominal adipose tissue depots (sc and visceral); 2) to relate it with gene expression of genes involved in lipid metabolism; and 3) to confirm that AQP7 is mainly expressed in the adipocytes.We conducted a transversal study of gene expression in paired samples of sc adipose tissue (SAT) and visceral adipose tissue (VAT).Caucasian lean and obese subjects (n = 62, matched for age and gender) and T2D subjects (n = 11, matched for age, gender, and BMI with their control group) participated in the study.We measured AQP7 expression levels in paired SAT and VAT.We have proved the presence of AQP7 mRNA and protein in the adipocyte rather than the stromovascular fraction of adipose tissue (P = 0.001) and in mature adipocytes when differentiated in vitro. Increased AQP7 mRNA expression levels in VAT from T2D obese subjects (P0.05) were found. AQP7 transcript levels ratio of SAT vs. VAT changed with the presence of obesity and T2D. Interestingly, there were positive associations between AQP7 and both lipogenic and lipolytic genes in a similar manner in both adipose depots.Taken together, these data suggest a subtle regulation between adipose depots of the sole adipose aquaporin, AQP7, which is unbalanced in obesity and T2D.

The trafficking of glycerol from adipose and hepatic tissue is mainly mediated by 2 aquaporin channel proteins: AQP7 and AQP9, respectively. In rodents, both aquaporins were found to act in a coordinated manner. The aim was to study the relationship between adipose AQP7 and hepatic AQP9 messenger RNA expression and the presence of glucose abnormalities simultaneously in morbid obesity. Adipose tissue (subcutaneous [SAT] and visceral [VAT]) and liver biopsies from the same patient were obtained during bariatric surgery in 30 (21 male and 9 female) morbidly obese subjects. Real-time quantification of AQP7 in SAT and VAT and hepatic AQP9 gene expression were performed. A 75-g oral glucose tolerance test was performed in all subjects. The homeostasis model assessment of insulin resistance and lipidic profile were also determined. Visceral adipose tissue AQP7 expression levels were significantly higher than SAT AQP7 (P = .009). Subcutaneous adipose tissue AQP7 positively correlated with both VAT AQP7 and hepatic AQP9 messenger RNA expression (r = 0.44, P = .013 and r = 0.45, P = .012, respectively). The correlation between SAT AQP7 and liver AQP9 was stronger in intolerant and type 2 diabetes mellitus subjects (r = 0.602, P = .011). We have found no differences in compartmental AQP7 adipose tissue distribution or AQP9 hepatic gene expression according to glucose tolerance classification. The present study provides, for the first time, evidence of coordinated regulation between adipose aquaglyceroporins, with a greater expression found in visceral fat, and between subcutaneous adipose AQP7 and hepatic AQP9 gene expression within the context of human morbid obesity.

Aquaporin-7 is required for efflux of glycerol from adipocytes and influences whole-body glucose homeostasis in animal studies.Our objective was to test the hypothesis that AQP7 gene expression levels may be affected by presence of obesity and type 2 diabetes in humans.The obesity study cohort consisted of 12 lean, 22 nonseverely obese, and 13 severely obese subjects. The type 2 diabetes study cohort consisted of 17 lean and 39 obese type 2 diabetic patients. Circulating levels of plasma soluble proteins monocyte chemoattractant protein-1, TNF receptors 1 and 2, and IL-6 and glycerol were measured. The sc adipose tissue gene expression of AQP7, MCP-1, IL-6, TNFalpha, PPARgamma, and SREBP1c genes was measured by real-time PCR. AQP7 gene mutation analysis was performed.Severely obese women showed lower AQP7 expression levels compared with lean and nonseverely obese (P0.001). Moreover, circulating glycerol concentration was lower in severely obese subjects, but no correlation with AQP7 adipose tissue expression was observed. AQP7 expression was negatively related with proinflammatory genes (for monocyte chemoattractant protein-1, r = -0.203 and P = 0.044; for TNFalpha, r = -0.209 and P = 0.036). Concerning adipogenic factors, AQP7 expression levels were found to be positively determined by PPARgamma mRNA expression levels (r = 0.265; P = 0.012). AQP7 expression did not show differences regarding the presence of type 2 diabetes.Expression of AQP7 is down-regulated in women with severe obesity. The expression of this glycerol channel is not affected by type 2 diabetes.

Objective Glycogen metabolism has emerged as a mediator in the control of energy homeostasis and studies in murine models reveal that adipose tissue might contain glycogen stores. Here we investigated the physio(patho)logical role of glycogen in human adipose tissue in the context of obesity and insulin resistance. Methods We studied glucose metabolic flux of hypoxic human adipoctyes by nuclear magnetic resonance and mass spectrometry-based metabolic approaches. Glycogen synthesis and glycogen content in response to hypoxia was analyzed in human adipocytes and macrophages. To explore the metabolic effects of enforced glycogen deposition in adipocytes and macrophages, we overexpressed PTG, the only glycogen-associated regulatory subunit (PP1-GTS) reported in murine adipocytes. Adipose tissue gene expression analysis was performed on wild type and homozygous PTG KO male mice. Finally, glycogen metabolism gene expression and glycogen accumulation was analyzed in adipose tissue, mature adipocytes and resident macrophages from lean and obese subjects with different degrees of insulin resistance in 2 independent cohorts. Results We show that hypoxia modulates glucose metabolic flux in human adipocytes and macrophages and promotes glycogenesis. Enforced glycogen deposition by overexpression of PTG re-orients adipocyte secretion to a pro-inflammatory response linked to insulin resistance and monocyte/lymphocyte migration. Furthermore, glycogen accumulation is associated with inhibition of mTORC1 signaling and increased basal autophagy flux, correlating with greater leptin release in glycogen-loaded adipocytes. PTG-KO mice have reduced expression of key inflammatory genes in adipose tissue and PTG overexpression in M0 macrophages induces a pro-inflammatory and glycolytic M1 phenotype. Increased glycogen synthase expression correlates with glycogen deposition in subcutaneous adipose tissue of obese patients. Glycogen content in subcutaneous mature adipocytes is associated with BMI and leptin expression. Conclusion Our data establish glycogen mishandling in adipose tissue as a potential key feature of inflammatory-related metabolic stress in human obesity., Highlights • Hypoxia redirects extracellular glucose to glycogen synthesis in human adipocytes. • Glycogen modifies the endocrine function of adipocytes and induces insulin resistance. • Glycogen stimulates leptin secretion through an autophagy-dependent mechanism. • Enforced glycogen accumulation in macrophages promotes M1 polarization. • Obesity is associated with higher GS expression and glycogen stores in adipose tissue.

Objective Evidence from mouse models suggests that zinc-α2-glycoprotein (ZAG) is a novel anti-obesity adipokine. In humans, however, data are controversial and its physiological role in adipose tissue (AT) remains unknown. Here we explored the molecular mechanisms by which ZAG regulates carbohydrate metabolism in human adipocytes. Methods ZAG action on glucose uptake and insulin action was analyzed. β1 and β2-adrenoreceptor (AR) antagonists and siRNA targeting PP2A phosphatase were used to examine the mechanisms by which ZAG modulates insulin sensitivity. Plasma levels of ZAG were measured in a lean patient cohort stratified for HOMA-IR. Results ZAG treatment increased basal glucose uptake, correlating with an increase in GLUT expression, but induced insulin resistance in adipocytes. Pretreatment of adipocytes with propranolol and a specific β1-AR antagonist demonstrated that ZAG effects on basal glucose uptake and GLUT4 expression are mediated via β1-AR, whereas inhibition of insulin action is dependent on β2-AR activation. ZAG treatment correlated with an increase in PP2A activity. Silencing of the PP2A catalytic subunit abrogated the negative effect of ZAG on insulin-stimulated AKT phosphorylation and glucose uptake but not on GLUT4 expression and basal glucose uptake. ZAG circulating levels were unchanged in a lean patient cohort stratified for HOMA-IR. Neither glucose nor insulin was associated with plasma ZAG. Conclusions ZAG inhibits insulin-induced glucose uptake in human adipocytes by impairing insulin signaling at the level of AKT in a β2-AR- and PP2A-dependent manner.

Context: Glucose-dependent insulinotropic peptide (GIP) has a central role in glucose homeostasis through its amplification of insulin secretion; however, its physiological role in adipose tissue is unclear. Objective: Our objective was to define the function of GIP in human adipose tissue in relation to obesity and insulin resistance. Design: GIP receptor (GIPR) expression was analyzed in human sc adipose tissue (SAT) and visceral adipose (VAT) from lean and obese subjects in 3 independent cohorts. GIPR expression was associated with anthropometric and biochemical variables. GIP responsiveness on insulin sensitivity was analyzed in human adipocyte cell lines in normoxic and hypoxic environments as well as in adipose-derived stem cells obtained from lean and obese patients. Results: GIPR expression was downregulated in SAT from obese patients and correlated negatively with body mass index, waist circumference, systolic blood pressure, and glucose and triglyceride levels. Furthermore, homeostasis model assessment of insulin resistance, glucose, and G protein-coupled receptor kinase 2 (GRK2) emerged as variables strongly associated with GIPR expression in SAT. Glucose uptake studies and insulin signaling in human adipocytes revealed GIP as an insulin-sensitizer incretin. Immunoprecipitation experiments suggested that GIP promotes the interaction of GRK2 with GIPR and decreases the association of GRK2 to insulin receptor substrate 1. These effects of GIP observed under normoxia were lost in human fat cells cultured in hypoxia. In support of this, GIP increased insulin sensitivity in human adipose-derived stem cells from lean patients. GIP also induced GIPR expression, which was concomitant with a downregulation of the incretin-degrading enzyme dipeptidyl peptidase 4. None of the physiological effects of GIP were detected in human fat cells obtained from an obese environment with reduced levels of GIPR. Conclusions: GIP/GIPR signaling is disrupted in insulin-resistant states, such as obesity, and normalizing this function might represent a potential therapy in the treatment of obesity-associated metabolic disorders.

For a long time Aquaporin-7 has been the only aquaporin associated with the adipose tissue, and its dysregulation has been linked to the underlying mechanisms of obesity. However, the presence of alternative glycerol channels within the adipose tissue has been postulated, which has prompted us to the search of alternate glycerol transport routes in adipocytes. In view of this, it is hypothesized that Aquaporin-11 (AQP11) would have a role in adipocyte cell biology.The expression, the localization and the function of human AQP11 (hAQP11) in cultured differentiated adipocytes were investigated.Gene expression analysis revealed the presence of AQP11 in both subcutaneous and visceral human mature adipocytes. It is found that hAQP11 is primarily located intracellularly in human adipocytes and partially colocalizes with perilipin, pointing towards AQP11 preferential location in the vicinity of lipid droplets. Overexpression of hAQP11 in 3T3-L1 adipocytes enabled to validate its function as a water channel and reveal its glycerol permeation activity.hAQP11 permeates both water and glycerol, localizing in the vicinity of lipid droplets in human adipocytes.

Aim This study investigated the relationship between endothelial dysfunction (ED) and arterial stiffness (AS) in adults with type 1 diabetes and no clinical cardiovascular (CV) disease. Methods A total of 68 patients with type 1 diabetes and 68 age- and gender-matched healthy (non-diabetic) subjects were evaluated. ED was assessed by reactive hyperaemia peripheral arterial tonometry (RH-PAT) and by serum concentrations of soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1 (sVCAM-1) and E-selectin. AS was assessed by aortic pulse wave velocity (aPWV). All statistical analyses were stratified by gender. Results Adults with type 1 diabetes had RH-PAT index scores similar to those of their matching controls [men: 1.55 (1.38–1.98)% versus 1.61 (1.40–2.17)%, P =0.556; women: 2.07 (1.55–2.31)% versus 2.08 (1.79–2.49)%; P =0.215]. However, after adjusting for potential confounders, type 1 diabetes emerged as the main determinant of the RH-PAT index in women. Also, differences between genders in both the controls and type 1 diabetes patients disappeared. Men with diabetes had higher serum concentrations of E-selectin, and women had higher serum concentrations of sICAM-1, sVCAM-1 and E-selectin than their respective controls. However, after adjusting for potential confounders, only the differences in sICAM-1 (women) and E-selectin (both genders) remained significant. No association was found between aPWV and the RH-PAT index and ED markers after adjusting for CV risk factors. Conclusion ED was increased in adults with type 1 diabetes compared with age-matched non-diabetic subjects. Also, gender differences in ED were lost in type 1 diabetes. However, ED was not associated with AS after adjusting for potential confounders. These findings suggest that ED occurs earlier than AS in type 1 diabetes.

Psoriasis has been related to metabolic syndrome (MS). Adipocytokines produced by white adipose tissue may be involved in the pathogenesis of psoriasis and its association with MS. Our objectives were to characterize the profile of a number of different inflammatory and atherogenic markers, vitamins, adipokines and cytokines and their potential involvement in MS in patients with moderate-to-severe psoriasis without joint involvement compared to anthropometrically matched controls, and to evaluate correlation with severity of the skin disease and changes after narrow-band UVB (NB-UVB) phototherapy. We designed a prospective cross-sectional study. Baseline waist circumference, body fat composition, lipid, carbohydrate and calcium metabolism profile, inflammation markers, homocysteine and vitamins D, B6, B12 and folic acid, leptin, resistin, omentin, lipocalin-2, adipocyte fatty acid-binding protein, retinol-binding protein-4 (RBP-4), interleukin-6, soluble tumour necrosis factor receptor 1 (sTNFR1) and interleukin-17 of 50 psoriasis patients and 50 gender, age and body mass index-matched controls were recorded, then evaluated after NB-UVB in the patients. The patients had higher baseline serum concentrations of leptin, RBP-4, lipocalin-2 and sTNFR1. Baseline psoriasis area and severity index correlated with serum concentrations of RBP-4 and lipocalin-2 only. Principal components analysis disclosed a component including vitamins B12, B6, folic acid, calcidiol and HDL-cholesterol that was only present in healthy controls and opposed to a cluster of variables which promote MS. This component was absent in the patients. Our results point to lipocalin-2 and RBP-4 as relevant mediators of the trend towards MS in psoriatic patients.

Objective We sought to analyze the role of cord blood adiponectin and its multimeric forms in neonatal adiposity and fetal growth velocity (FGV) during the third trimester of pregnancy according to fetal gender. Study design This was a prospective analytical observational study conducted at the Diabetes and Pregnancy Unit, University Hospital Joan XXIII, Tarragona, Spain. In all, 96 healthy pregnant women were included in the early third trimester and were followed up until delivery. Maternal blood was obtained upon recruitment, and cord blood was obtained at delivery. Serial fetal ultrasounds were performed during the third trimester to assess FGV. Skinfolds were measured after birth to assess neonatal adiposity. Adiponectin multimers were determined in maternal and cord blood. Results In female neonates, adiposity and FGV in the late third trimester were correlated positively with cord blood insulin (r = 0.343, P = .015 and r = 0.430, P = .002, respectively) and maternal pregravid body mass index (r = 597, P P = .002, respectively), and negatively with maternal high-molecular-weight (HMW)/total adiponectin ratio (r = −0.269, P = .035 and r = −0.387, P = .005, respectively), but in the stepwise multiple regression model, the main determinants were cord blood insulin, pregravid body mass index, and cord blood HMW adiponectin. Otherwise, in male neonates, adiposity and fetal growth were correlated with cord blood low-molecular-weight adiponectin (r = 0.486, P = .003 and r = 0.394, P = .020, respectively), and it was this multimeric form that emerged as an independent determinant in the stepwise regression model. Conclusion Adiponectin seems to determine fetal growth and adipose tissue accretion, and low molecular weight is more specifically implicated in males, whereas the HMW isoform may be more important in females.

LPIN1 is a gene with important effects on lipidic and metabolic homeostasis. Human subcutaneous LPIN1 expression levels in adipose tissue are related with a better metabolic profile, including insulin sensitivity markers. However, there are few data on the regulation of LPIN1 in visceral adipose tissue (VAT). Our aim was to perform a cross-sectional analysis of VAT compared with subcutaneous (SAT) LPIN1 expression in a well-characterized obese cohort, its relation with the expression of genes involved in lipid metabolism, and the in vitro response to lipogenic and lipolytic stimuli. A downregulation of total LPIN1 mRNA expression in subjects with obesity was found in VAT similarly to that in SAT. Despite similar total LPIN1 mRNA levels in SAT and VAT, a close relationship with clinical parameters and with many lipogenic and lipolytic genes was observed primarily in SAT depot. As shown in the in vitro analysis, the low-grade proinflammatory environment and the insulin resistance associated with obesity may contribute to downregulate LPIN1 in adipose tissue, leading to a worse metabolic profile.

Context: LPIN1 is the phosphatidic acid phosphatase that produces 1,2-diacylglycerol, and thus it is related to the synthesis of triglycerides in the adipocyte. LPIN1 has a role in lipid synthesis and nuclear receptor coactivation, both of which may be involved in lipid homeostasis and metabolism. Among others, hypoxia and endoplasmic reticulum (ER) stress are being shown to be related to the adipose dysfunction found in human obesity. Objective: The aim of this study was to analyze LPIN1 gene expression in human adipose tissue in parallel with several hypoxia, angiogenic, ER stress and peroxisome proliferator-activated receptor (PPAR)-related genes in human obesity. Design and Patients: Gene expression was quantified in abdominal (subcutaneous and visceral) adipose tissue from 62 subjects. Results: We have shown a marked association between LPIN1 and PPARα gene expression both in subcutaneous and visceral adipose tissues. Similarly, a strong interdependence with vascular endothelial growth factor (VEGF) gene expression was also described; in fact, LPIN1 and VEGF expression levels were significantly decreased with obesity to a similar extent. Conclusion: These associations might suggest a possible role of LPIN1 in stress conditions that occur in chronic obesity and underlie insulin resistance.

Context: Zinc-α2-glycoprotein (ZAG) is a soluble protein similar to the class I major histocompatibility complex heavy chain, which has been implicated in lipid catabolism. We hypothesized that ZAG mRNA expression in adipose tissue may be linked with lipolytic and adipokine gene expression and have a close relationship with clinical phenotype.Objectives: The objective of the study was to analyze ZAG gene expression in human adipose tissue from lean and obese subjects. ZAG circulating plasma levels and its relationship with cardiometabolic risk factors were also studied.Design: Seventy-three Caucasian (43 male and 30 female) subjects were included. Plasma and adipose tissue [sc (SAT) and visceral (VAT)] from the same patient were studied. mRNA of PPARγ, hormone-sensitive lipase (HSL), adipose triglyceride lipase, adiponectin, omentin, visfatin, and ZAG were quantified. Plasma concentrations of ZAG were determined with ELISA.Results: ZAG plasma levels showed a negative correlation with insulin (r = −0.39; P = 0.008) and the homeostasis model assessment for insulin resistance index (r = −0.36; P = 0.016). No differences in ZAG circulating levels according to body mass index classification were observed.ZAG expression in SAT was significantly reduced in overweight and obese individuals compared with lean subjects (P < 0.001 and P = 0.007, respectively). ZAG mRNA expression in both SAT and VAT depots were negatively correlated with many clinical and metabolic cardiovascular risk factors. After multiple linear regression analysis, SAT ZAG was mainly predicted by adiponectin mRNA expression (B = 0.993; P < 0.0001) and plasma triglyceride levels (B = −0.565; P = 0.006). VAT ZAG expression was predicted by adiponectin expression (B = 0.449; P < 0.0001), and HSL VAT expression (B = 0.180; P = 0.023).Conclusions: The present study provides evidence of a role of ZAG gene in adipose tissue metabolism, with a close association with adiponectin gene expression in sc and visceral fat.

Flavonoids are functional constituents of many fruits and vegetables. Procyanidins are flavonoids with an oligomeric structure, and it has been shown that they can improve the pathological oxidative state of a diabetic situation. To evaluate whether procyanidins can modulate inflammation, an event strongly associated with obesity, diabetes and insulin resistance states, we used human adipocytes (SGBS) and macrophage-like (THP-1) cell lines and administered an extract of grape-seed procyanidins (GSPE). THP-1 and SGBS cells pre-treated with GSPE showed a reduction of IL-6 and MCP-1 expression after an inflammatory stimulus. GSPE stimuli alone modulate adipokine (APM1 and LEP) and cytokine (IL-6 and MCP-1) gene expression. GSPE partially inhibited NF-kappaB translocation to the nucleus in both cell lines. These preliminary findings demonstrate that GSPE reduces the expression of IL-6 and MCP-1 and enhances the production of the anti-inflammatory adipokine adiponectin suggesting that may have a beneficial effect on low-grade inflammatory diseases such obesity and type 2 diabetes.

The aim of this study was to analyze LPIN1 adipose tissue gene expression levels in 3 clinical insulin-resistant conditions-obesity, type 2 diabetes mellitus, and human immunodeficiency virus (HIV)-associated lipodystrophy-and its relationship with adipogenic and inflammatory markers. Subcutaneous adipose tissue samples were obtained from 2 cohorts: 98 subjects with different degrees of adiposity and with or without the presence of type 2 diabetes mellitus and 37 HIV-infected patients. Real-time polymerase chain reaction was used to measure gene expression of LPIN1 and adipogenic (PPARgamma, SREBP1c) and inflammatory markers (IL6, TNFalpha, TNFR1, and TNFR2). LPIN1 messenger RNA expression levels were significantly lower in the obese group (P = .002), were similar in type 2 diabetes mellitus patients and control subjects (P = .211), and were significantly higher in HIV-infected patients (P < .001). LPIN1 messenger RNA levels positively correlated with insulin sensitivity in all subjects. Moreover, an inverse correlation with proinflammatory cytokines was observed.

This is an open-access article distributed under the terms of the Creative Commons Attribution License.-- et al., [Background]: FABP4 is predominantly expressed in adipose tissue, and its circulating levels are linked with obesity and a poor atherogenic profile. [Objective]: In patients with a wide BMI range, we analyze FABP4 expression in adipose and hepatic tissues in the settings of obesity and insulin resistance. Associations between FABP4 expression in adipose tissue and the FABP4 plasma level as well as the main adipogenic and lipolytic genes expressed in adipose tissue were also analyzed. [Methods]: The expression of several lipogenic, lipolytic, PPAR family and FABP family genes was analyzed by real time PCR. FABP4 protein expression in total adipose tissues and its fractions were determined by western blot. [Results]: In obesity FABP4 expression was down-regulated (at both mRNA and protein levels), with its levels mainly predicted by ATGL and inversely by the HOMA-IR index. The BMI appeared as the only determinant of the FABP4 variation in both adipose tissue depots. FABP4 plasma levels showed a significant progressive increase according to BMI but no association was detected between FABP4 circulating levels and SAT or VAT FABP4 gene expression. The gene expression of FABP1, FABP4 and FABP5 in hepatic tissue was significantly higher in tissue from the obese IR patients compared to the non-IR group. [Conclusion]: The inverse pattern in FABP4 expression between adipose and hepatic tissue observed in morbid obese patients, regarding the IR context, suggests that both tissues may act in a balanced manner. These differences may help us to understand the discrepancies between circulating plasma levels and adipose tissue expression in obesity. © 2012 Queipo Ortuño et al., This work was supported by Fondo de Investigacion Sanitaria (FIS) 07/1024, 08/1195, CB06/03/0018, CP07/0095 and PI081655, 10/00967, 11/00085 from the Spanish Instituto de Salud Carlos III (ISCIII), Ministerio de Sanidad y Consumo; with the participation of the European Regional Development Fund (ERDF) SAF-2009-10461 from the Ministerio de Economia y Competitividad (MICINN), the Servicio Andaluz de Salud (PI325/2008) and Fundación Mutua Madrileña, Spain (BP). LGS and VCM are supported by fellowships from the Juan de la Cierva programme (JdlC) (JCI200904086 and JCI-2010-06395). CIBERs are an ISCIII Project.