Nutrition and stem cell integrity in aging.

Adult stem cells (SCs) represent the regenerative capacity of organisms throughout their lifespan. The maintenance of robust SC populations capable of renewing organs and physiological systems is one hallmark of healthy aging. The local environment of SCs, referred to as the niche, includes the nutritional milieu, which is essential to maintain the quantity and quality of SCs available for renewal and regeneration. There is increased recognition that SCs have unique metabolism and conditional nutrient needs compared to fully differentiated cells. However, the contribution of SC nutrition to overall human nutritional requirements is an understudied and underappreciated area of investigation. Nutrient needs vary across the lifespan and are modified by many factors including individual health, disease, physiological states including pregnancy, age, sex, and during recovery from injury. Although current nutrition guidance is generally derived for apparently healthy populations and to prevent nutritional deficiency diseases, there are increased efforts to establish nutrient-based and food-based recommendations based on reducing chronic disease. Understanding the dynamics of SC nutritional needs throughout the life span, including the role of nutrition in extending biological age by blunting biological systems decay, is fundamental to establishing food and nutrient guidance for chronic disease reduction and health maintenance. This review summarizes a 3-day symposium of the Marabou Foundation (www.marabousymposium.org) held to examine the metabolic properties and unique nutritional needs of adult SCs and their role in healthy aging and age-related chronic disease.

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

BACKGROUND/OBJECTIVES: Bariatric surgery improves nonalcoholic fatty liver disease (NAFLD) and nonalcoholic steatohepatitis (NASH), but the underlying mechanisms remain elusive. We evaluated the potential role of ghrelin isoforms in the amelioration of hepatic inflammation after sleeve gastrectomy and Roux-en-Y gastric bypass (RYGB). SUBJECTS/METHODS: Plasma ghrelin isoforms were measured in male Wistar rats (n = 129) subjected to surgical (sham operation, sleeve gastrectomy, or RYGB) or dietary interventions [fed ad libitum a normal (ND) or a high-fat diet (HFD) or pair-fed diet]. The effect of acylated and desacyl ghrelin on markers of inflammation, mitochondrial dysfunction, and endoplasmic reticulum (ER) stress in primary rat hepatocytes under palmitate-induced lipotoxic conditions was assessed. RESULTS: Plasma desacyl ghrelin was decreased after sleeve gastrectomy and RYGB, whereas the acylated/desacyl ghrelin ratio was augmented. Both surgeries diminished obesity-associated hepatic steatosis, CD68+- and apoptotic cells, proinflammatory JNK activation, and Crp, Tnf, and Il6 transcripts. Moreover, a postsurgical amelioration in the mitochondrial DNA content, oxidative phosphorylation (OXPHOS) complexes I and II, and ER stress markers was observed. Specifically, following bariatric surgery GRP78, spliced XBP-1, ATF4, and CHOP levels were reduced, as were phosphorylated eIF2α. Interestingly, acylated and desacyl ghrelin inhibited steatosis and inflammation of palmitate-treated hepatocytes in parallel to an upregulation of OXPHOS complexes II, III, and V, and a downregulation of ER stress transducers IRE1α, PERK, ATF6, their downstream effectors, ATF4 and CHOP, as well as chaperone GRP78. CONCLUSIONS: Our data suggest that the increased relative acylated ghrelin levels after bariatric surgery might contribute to mitigate obesity-associated hepatic inflammation, mitochondrial dysfunction, and ER stress.

Nutrition and its role in human evolution.

Our understanding of human evolution has improved rapidly over recent decades, facilitated by large-scale cataloguing of genomic variability amongst both modern and archaic humans. It seems clear that the evolution of the ancestors of chimpanzees and hominins separated 7-9 million years ago with some migration out of Africa by the earlier hominins; Homo sapiens slowly emerged as climate change resulted in drier, less forested African conditions. The African populations expanded and evolved in many different conditions with slow mutation and selection rates in the human genome, but with much more rapid mutation occurring in mitochondrial DNA. We now have evidence stretching back 300 000 years of humans in their current form, but there are clearly four very different large African language groups that correlate with population DNA differences. Then, about 50 000-100 000 years ago a small subset of modern humans also migrated out of Africa resulting in a persistent signature of more limited genetic diversity amongst non-African populations. Hybridization with archaic hominins occurred around this time such that all non-African modern humans possess some Neanderthal ancestry and Melanesian populations additionally possess some Denisovan ancestry. Human populations both within and outside Africa also adapted to diverse aspects of their local environment including altitude, climate, UV exposure, diet and pathogens, in some cases leaving clear signatures of patterns of genetic variation. Notable examples include haemoglobin changes conferring resistance to malaria, other immune changes and the skin adaptations favouring the synthesis of vitamin D. As humans migrated across Eurasia, further major mitochondrial changes occurred with some interbreeding with ancient hominins and the development of alcohol intolerance. More recently, an ability to retain lactase persistence into adulthood has evolved rapidly under the environmental stimulus of pastoralism with the ability to husband lactating ruminants. Increased amylase copy numbers seem to relate to the availability of starchy foods, whereas the capacity to desaturase and elongate monounsaturated fatty acids in different societies seems to be influenced by whether there is a lack of supply of readily available dietary sources of long-chain polyunsaturated fatty acids. The process of human evolution includes genetic drift and adaptation to local environments, in part through changes in mitochondrial and nuclear DNA. These genetic changes may underlie susceptibilities to some modern human pathologies including folate-responsive neural tube defects, diabetes, other age-related pathologies and mental health disorders.

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

BACKGROUND/OBJECTIVES: Obesity is related to a dynamic extracellular matrix (ECM) remodeling, which involves the synthesis and degradation of different proteins, such as tenascin C (TNC) in the adipose tissue (AT). Given the functional relationship between leptin and inducible nitric oxide synthase (iNOS), our aim was to analyze the impact of the absence of the iNOS gene in AT inflammation and ECM remodeling in ob/ob mice. SUBJECTS/METHODS: The expression of genes involved in inflammation and ECM remodeling was evaluated in 10-week-old male double knockout (DBKO) mice simultaneously lacking the ob and iNOS genes as well as in ob/ob mice classified into three groups [control, leptin-treated (1 mg kg-1 day-1) and pair-fed]. RESULTS: Leptin deficiency increased inflammation and fibrosis in AT. As expected, leptin treatment improved the obesity phenotype. iNOS deficiency in ob/ob mice improved insulin sensitivity, AT inflammation, and ECM remodeling, as evidenced by lower AT macrophage infiltration and collagen deposition, a downregulation of proinflammatory and profibrogenic genes Tnf, Emr1, Hif1a, Col6a1, Col6a3, and Tnc, as well as lower circulating TNC levels. Interestingly, leptin upregulated TNC expression and release in 3T3-L1 adipocytes, and iNOS knockdown in 3T3-L1 fat cells produced a significant decrease in basal and leptin-induced Tnc expression. CONCLUSIONS: Ablation of iNOS in leptin-deficient mice improved AT inflammation and ECM remodeling-related genes, attenuating fibrosis, and metabolic dysfunction. The activation of iNOS by leptin is necessary for the synthesis and secretion of TNC in adipocytes, suggesting an important role of this alarmin in the development of AT inflammation and fibrosis.

Dissociation of body mass index, excess weight loss and body fat percentage trajectories after 3 years of gastric bypass: relationship with metabolic outcomes.

BACKGROUND/OBJECTIVES: Body weight, body mass index (BMI) and excess weight loss (EWL) are the most frequently used measures to analyse bariatric surgery outcomes. However, these measurements do not provide accurate information on body composition (BC) with body fat (BF), importantly determining the levels of cardiometabolic risk factors. Our aim was to analyse the evolution of BC after Roux-en-Y Gastric Bypass (RYGB) and its influence on the changes of cardiometabolic risk factors in comparison to BMI and EWL. SUBJECTS/METHODS: A group of 81 obese Caucasian patients (19 males/62 females) aged 44.9±1.3 years undergoing RYGB between January 2006 and December 2011 was prospectively followed up for a period of 3 years. BC was determined by air-displacement plethysmography. Visceral adiposity, physical activity and cardiometabolic risk factors were measured. RESULTS: BF was markedly (P<0.001) reduced after the first year, increasing progressively during the second and third years after RYGB, following a different trajectory than body weight, BMI and EWL that decreased up to the second year post surgery. Markers of glucose homeostasis decreased during the first month and continued to decrease during the first year (P<0.05), remaining stabilised or slightly increased between the second and third years following RYGB. However, markers of lipid metabolism decreased (P<0.05) markedly during the first 12 months, increasing thereafter in parallel to the changes observed in BC, with the exception of high-density lipoprotein-cholesterol, which increased progressively throughout the whole period analysed. CONCLUSIONS: The adverse switch in the changes in BC between the first and the second years after RYGB may underlie the changes observed in cardiometabolic risk factors. Tracking of adiposity during the follow-up of bariatric/metabolic surgery yields clinically relevant information to better identify patients in need of increased lifestyle advice or treatment intensification.

Role of aquaporin-7 in ghrelin- and GLP-1-induced improvement of pancreatic ß-cell function after sleeve gastrectomy in obese rats.

BACKGROUND/OBJECTIVES: Glycerol is a key metabolite for lipid accumulation in insulin-sensitive tissues as well as for pancreatic insulin secretion. We examined the role of aquaporin-7 (AQP7), the main glycerol channel in ß-cells, and AQP12, an aquaporin related to pancreatic damage, in the improvement of pancreatic function and steatosis after sleeve gastrectomy in diet-induced obese rats. SUBJECTS/METHODS: Male Wistar obese rats (n=125) were subjected to surgical (sham operation and sleeve gastrectomy) or dietary (pair-fed to the amount of food eaten by sleeve-gastrectomized animals) interventions. The tissue distribution and expression of AQPs in the rat pancreas were analyzed by real-time PCR, western blotting and immunohistochemistry. The effect of ghrelin isoforms and glucagon-like peptide 1 (GLP-1) on insulin secretion, triacylglycerol (TG) accumulation and AQP expression was determined in vitro in RIN-m5F ß-cells. RESULTS: Sleeve gastrectomy reduced pancreatic ß-cell apoptosis, steatosis and insulin secretion. Lower ghrelin and higher GLP-1 concentrations were also found after bariatric surgery. Acylated and desacyl ghrelin increased TG content, whereas GLP-1 increased insulin release in RIN-m5F ß-cells. Sleeve gastrectomy was associated with an upregulation of AQP7 together with a normalization of the increased AQP12 levels in the rat pancreas. Interestingly, ghrelin and GLP-1 repressed AQP7 and AQP12 expression in RIN-m5F ß-cells. AQP7 protein was negatively correlated with intracellular lipid accumulation in acylated ghrelin-treated cells and with insulin release in GLP-1-stimulated ß-cells. CONCLUSIONS: AQP7 upregulation in ß-cells after sleeve gastrectomy contributes, in part, to the improvement of pancreatic steatosis and insulin secretion by increasing intracellular glycerol used for insulin release triggered by GLP-1 rather than for ghrelin-induced TG biosynthesis.

Guanylin and uroguanylin stimulate lipolysis in human visceral adipocytes.

BACKGROUND/OBJECTIVES: Uroguanylin and guanylin are secreted by intestinal epithelial cells as prohormones postprandially and act on the hypothalamus to induce satiety. The impact of obesity and obesity-associated type 2 diabetes (T2D) on proguanylin and prouroguanylin expression/secretion as well as the potential role of guanylin and uroguanylin in the control of lipolysis in humans was evaluated. SUBJECTS/METHODS: Circulating and gastrointestinal expression of proguanylin (GUCA2A) and prouroguanylin (GUCA2B) were measured in 134 subjects. In addition, plasma proguanylin and prouroguanylin were measured before and after weight loss achieved either by Roux-en-Y gastric bypass (RYGB) (n=24) or after a conventional diet (n=15). The effect of guanylin and uroguanylin (1-100 nmol l(-1)) on lipolysis was determined in vitro in omental adipocytes. RESULTS: Circulating concentrations of prouroguanylin, but not proguanylin, were decreased in obesity in relation to adiposity. Weight loss achieved by RYGB increased plasma proguanylin and prouroguanylin. Obese T2D individuals showed higher expression of intestinal GUCA2A as well as of the receptors of the guanylin system, GUCY2C and GUCY2D, in omental adipocytes. The incubation with guanylin and uroguanylin significantly stimulated lipolysis in differentiated omental adipocytes, as evidenced by hormone-sensitive lipase phosphorylation at Ser563, an increase in fatty acids and glycerol release together with an upregulation of several lipolysis-related genes, including AQP3, AQP7, FATP1 or CD36. CONCLUSIONS: Both guanylin and uroguanylin trigger lipolysis in human visceral adipocytes. Given the lipolytic action of the guanylin system on visceral adipocytes, the herein reported decrease of circulating prouroguanylin concentrations in obese patients may have a role in excessive fat accumulation in obesity.

Leptin administration activates irisin-induced myogenesis via nitric oxide-dependent mechanisms, but reduces its effect on subcutaneous fat browning in mice.

UNLABELLED: BACKGROUND/OBJETIVES: Obese leptin-deficient ob/ob mice exhibit high adiposity and reduced muscle mass with leptin replacement promoting weight loss and inducing muscle accretion through PGC-1α-dependent mechanisms. Our aim was to analyze in vivo and in vitro the effect of leptin on FNDC5, a novel PGC-1α-dependent myokine that is synthesized and cleaved to form irisin that induces white adipose browning. METHODS/RESULTS: Twelve-week-old male wild-type and ob/ob mice were divided in three groups as follows: control, leptin-treated (1 mg kg(-1) day(-1)) and pair-fed. Leptin administration was associated with increased gastrocnemius weight and cell surface area, higher Pgc1a and Fndc5 transcript levels and a slight increase in circulating irisin. Leptin upregulated Fndc5 expression through nitric oxide (NO)-dependent mechanisms in murine C2C12 myocytes and stimulated both basal and irisin-stimulated myogenesis, as evidenced by increased myocyte cell proliferation, higher myogenin and myonectin transcript levels together with lower mRNA expression of myostatin and dystrophin and the muscle atrophy-related factors MuRF1 and MAFbx. Interestingly, leptin downregulated Fndc5 expression in a NO-independent manner in murine differentiated subcutaneous adipocytes. Furthermore, leptin prevented the irisin-induced upregulation of both brown (Ucp1 and Cidec) and beige (Tmem26) adipocyte-specific genes and the increase in uncoupling protein-1-positive cells. CONCLUSIONS: Taken together, our results provide evidence for a regulatory role of leptin on FNDC5/irisin, favoring muscle accretion but reducing fat browning.

Opposite alterations in FGF21 and FGF19 levels and disturbed expression of the receptor machinery for endocrine FGFs in obese patients.

OBJECTIVE: Fibroblast growth factor (FGF)-21, and possibly FGF19, protect against type 2 diabetes mellitus (T2DM) and obesity in rodents. We investigated the circulating levels of FGF21 and FGF19 in obese patients with varying degrees of abnormal glucose homeostasis, and we determined gene expression for FGF receptors (FGFR1-4) and the co-receptor ß-Klotho, in liver and adipose tissues. SUBJECTS AND METHODS: We analyzed 35 lean healthy (71% men) and 61 obese patients (49% men, median body mass index (BMI): 40.5 kg m(-2), interquartile range: 34.7-46.2). Among obese patients, 36 were normoglycemic, 15 showed impaired glucose tolerance and 10 had T2DM. Biopsies from liver and visceral and subcutaneous fat from a subset of obese patients and controls were analyzed. FGF19 and FGF21 levels were measured using enzyme-linked immunosorbent assay, and tissue mRNA and protein levels by reverse transcription-polymerase chain reaction and immunoblotting. RESULTS: FGF21 serum levels were significantly increased in obese patients compared with controls (P<0.001), whereas FGF19 levels were decreased (P < 0.001). FGF21 levels were positively correlated with homeostasis model assessment of insulin resistance (P = 0.0002, r = 0.37) and insulin (P = 0.001, r = 0.32), whereas FGF19 levels were negatively correlated (P = 0.007, r = -0.27; P=0.003, r = -0.28; respectively). After adjusting for BMI, the correlations of FGF21 and FGF19 levels with indicators of abnormal glucose homeostasis were not significant. In obese patients, the hepatic expression of FGF21 was increased. (P = 0.04). ß-Klotho transcript levels in visceral fat (P = 0.002) and ß-Klotho protein levels in subcutaneous (P = 0.03) and visceral fat (P = 0.04) were significantly reduced in obese patients, whereas hepatic levels for ß-Klotho (P = 0.03), FGFR1 (P = 0.04) and FGFR3 (P = 0.001) transcripts were significantly increased. CONCLUSIONS: Obesity is characterized by reciprocal alterations in FGF19 (decrease) and FGF21 (increase) levels. Although worsened in diabetic obese patients, obesity itself appears as the predominant determinant of the abnormalities in FGF21 and FGF19 levels. Opposite changes in ß-Klotho expression in fat and liver indicate potential tissue-specific alterations in the responsiveness to endocrine FGFs in obesity.

Characterising metabolically healthy obesity in weight-discordant monozygotic twins.

AIMS/HYPOTHESIS: Not all obese individuals display the metabolic disturbances commonly associated with excess fat accumulation. Mechanisms maintaining this 'metabolically healthy obesity' (MHO) are as yet unknown. We aimed to study different fat depots and transcriptional pathways in subcutaneous adipose tissue (SAT) as related to the MHO phenomenon. METHODS: Sixteen rare young adult obesity-discordant monozygotic (MZ) twin pairs (intra-pair difference (∆) in BMI ≥ 3 kg/m(2)), aged 22.8-35.8 years, were examined for detailed characteristics of metabolic health (subcutaneous, intra-abdominal and liver fat [magnetic resonance imaging/spectroscopy]), OGTT, lipids, adipokines and C-reactive protein (CRP). Affymetrix U133 Plus 2.0 chips were used to analyse transcriptomics pathways related to mitochondrial function and inflammation in SAT. RESULTS: Based on liver fat accumulation, two metabolically different subgroups emerged. In half (8/16) of the pairs (∆weight 17.1 ± 2.0 kg), the obese co-twin had significantly higher liver fat (∆718%), 78% increase in AUC insulin during OGTT and CRP, significantly more disturbance in the lipid profile and greater tendency for hypertension compared with the lean co-twin. In these obese co-twins, SAT expression of mitochondrial oxidative phosphorylation, branched-chain amino acid catabolism, fatty acid oxidation and adipocyte differentiation pathways were downregulated and chronic inflammation upregulated. In the other eight pairs (∆weight 17.4 ± 2.8 kg), the obese co-twin did not differ from the non-obese co-twin in liver fat (∆8%), insulin sensitivity, CRP, lipids, blood pressure or SAT transcriptomics. CONCLUSIONS/INTERPRETATION: Our results suggest that maintenance of high mitochondrial transcription and lack of inflammation in SAT are associated with low liver fat and MHO.

Adipocyte morphology and implications for metabolic derangements in acquired obesity.

BACKGROUND: Adipocyte size and number have been suggested to predict the development of metabolic complications in obesity. However, the genetic and environmental determinants behind this phenomenon remain unclear. METHODS: We studied this question in rare-weight discordant (intra-pair difference (Δ) body mass index (BMI) 3-10 kg m(-2), n=15) and concordant (ΔBMI 0-2 kg m(-)(2), n=5) young adult (22-35 years) monozygotic twin pairs identified from 10 birth cohorts of Finnish twins (n=5 500 pairs). Subcutaneous abdominal adipocyte size from surgical biopsies was measured under a light microscope. Adipocyte number was calculated from cell size and total body fat (D × A). RESULTS: The concordant pairs were remarkably similar for adipocyte size and number (intra-class correlations 0.91-0.92, P<0.01), suggesting a strong genetic control of these measures. In the discordant pairs, the obese co-twins (BMI 30.6 ± 0.9 kg m(-2)) had significantly larger adipocytes (volume 547 ± 59 pl), than the lean co-twins (24.9 ± 0.9 kg m(-)(2); 356 ± 34 pl, P<0.001). In 8/15 pairs, the obese co-twins had less adipocytes than their co-twins. These hypoplastic obese twins had significantly higher liver fat (spectroscopy), homeostatic model assessment-index, C-reactive protein and low-density lipoprotein cholesterol than their lean co-twins. Hyperplastic obesity was observed in the rest (7/15) of the pairs, obese and lean co-twins having similar metabolic measures. In all pairs, Δadipocyte volume correlated positively and Δcell number correlated negatively with Δhomeostatic model assessment-index and Δlow-density lipoprotein, independent of Δbody fat. Transcripts most significantly correlating with Δadipocyte volume were related to a reduced mitochondrial function, membrane modifications, to DNA damage and cell death. CONCLUSIONS: Together, hypertrophy and hypoplasia in acquired obesity are related to metabolic dysfunction, possibly through disturbances in mitochondrial function and increased cell death within the adipose tissue.

Reduced hepatic aquaporin-9 and glycerol permeability are related to insulin resistance in non-alcoholic fatty liver disease.

BACKGROUND/OBJECTIVES: Glycerol represents an important metabolite for the control of lipid accumulation and hepatic gluconeogenesis. We investigated whether hepatic expression and functionality of aquaporin-9 (AQP9), a channel mediating glycerol influx into hepatocytes, is impaired in non-alcoholic fatty liver disease (NAFLD) and steatohepatitis (NASH) in the context of insulin resistance. SUBJECTS/METHODS: Liver biopsies were obtained from 66 morbid obese patients undergoing bariatric surgery (66% women, mean body mass index (BMI) 46.1±1.0 kg m(-2)) with available liver echography and pathology analysis of the biopsies in this cross-sectional study. Subjects were classified according to normoglycemia (NG), impaired glucose tolerance (IGT) or type 2 diabetes (T2D). Hepatic expression of AQP9 was analyzed by real-time PCR, western blotting and immunohistochemistry, while glycerol permeability (P(gly)) was measured by stopped-flow light scattering. RESULTS: AQP9 was the most abundantly (P<0.0001) expressed aquaglyceroporin in human liver (AQP9>>>AQP3>AQP7>AQP10). Obese patients with T2D showed increased plasma glycerol as well as lower P(gly) and hepatic AQP9 expression. The prevalence of NAFLD and NASH in T2D patients was 100 and 65%, respectively. Interestingly, AQP9 expression was decreased in patients with NAFLD and NASH as compared with those without hepatosteatosis, in direct relation to the degree of steatosis and lobular inflammation, being further reduced in insulin-resistant individuals. The association of AQP9 with insulin sensitivity was independent of BMI and age. Consistent with these data, fasting insulin and C-reactive protein contributed independently to 33.1% of the hepatic AQP9 mRNA expression variance after controlling for the effects of age and BMI. CONCLUSIONS: AQP9 downregulation together with the subsequent reduction in hepatic glycerol permeability in insulin-resistant states emerges as a compensatory mechanism whereby the liver counteracts further triacylglycerol accumulation within its parenchyma as well as reduces hepatic gluconeogenesis in patients with NAFLD.

Inflammation and insulin resistance exert dual effects on adipose tissue tumor protein 53 expression.

OBJECTIVE: The purpose of this study was to investigate the expression of human adipose tissue protein 53 (p53) in subjects who varied widely in terms of obesity and insulin resistance. We also analyzed different in vivo and in vitro models to try to comprehend the associations found in humans. METHODS: p53 was analyzed in human adipose and isolated adipocytes, in high fat-fed and GLP-1R KO mice, during in vitro adipogenesis, and in adipocytes after high glucose, rosiglitazone and inflammatory conditions. The effects of surgery-induced weight loss and ex vivo metformin were also evaluated. RESULTS: Omental (OM) p53 gene expression (+27%, P=0.001) and protein (+11%, P=0.04) were increased in obese subjects and high fat diet-induced obese mice (+86%, P=0.018). Although the obesity-associated inflammatory milieu was associated with increased OM p53, this was negatively related to insulin resistance and glycated hemoglobin, and positively with biomarkers for insulin sensitivity. Multiple linear regression analyses revealed that glycated hemoglobin (P<0.0001) and body mass index (P=0.048) contributed independently to explain 13.7% (P<0.0001) of the OM p53 variance. Accordingly, the improvement of insulin sensitivity with surgery-induced weight loss (+51%, P=0.01) and metformin (+42%, P=0.02) led to increased adipose p53. While the glucose-intolerant GLP-1R KO mice showed decreased mesenteric p53 (-45.4%, P=0.017), high glucose led to decreased p53 in pre-adipocytes (-27%, P<0.0001). Inflammatory treatments led to increased p53 (+35%, P<0.0001), while Rs downregulated this expression (-40%, P=0.005) in mature adipocytes. CONCLUSION: Inflammation and insulin resistance exert dual effects on adipose p53, which seems to be the final result of these opposing forces.

Alarmin high-mobility group B1 (HMGB1) is regulated in human adipocytes in insulin resistance and influences insulin secretion in ß-cells.

BACKGROUND: The nuclear protein high-mobility group box 1 (HMGB1) can be passively released by necrotic cells or secreted actively by several cell types to regulate immune and inflammatory responses, as well as tissue remodeling. We herein aimed to characterize the effect of insulin resistance on HMGB1 in adipose tissue and to examine its potential role as a metabolic regulator in ß-pancreatic cells. DESIGN: Plasma HMGB1 concentration and adipose HMGB1 expression were assessed in relation to obesity and insulin resistance. Cultured adipocytes from lean and obese patients were used to investigate the intracellular distribution and factors regulating HMGB1 release, as well as to test its effects on adipogenesis and lipid metabolism. A regulatory role for HMGB1 in insulin secretion was also investigated. RESULTS: Circulating HMGB1 was positively associated with body mass index, while adipose HMGB1 mRNA levels correlated with the expression of inflammatory markers. Insulin resistance modified the intracellular distribution of HMGB1 in human adipocytes, with HMGB1 being predominantly nuclear in lean and obese normoglycemic individuals while localized to the cytosol in obese patients with type 2 diabetes. Adipocytes from lean individuals exposed to conditioned media from lipopolysaccharide-stimulated macrophages induced HMGB1 redistribution to the cytoplasm and release. HMGB1 treatment had no effect on differentiation and lipid metabolism in adipocytes. However, HMGB1, whose circulating levels correlated with postload insulin concentration, increased both insulin release and intracellular Ca(2+) concentration in INS-1 cells. CONCLUSIONS: These findings show, for the first time, that HMGB1 expression and release by human adipocytes is altered by inflammatory conditions as those imposed by obesity and insulin resistance. Our data reveal a novel role for HMGB1 as a stimulatory factor of insulin secretion of ß-pancreatic cells.

[Interdisciplinary European guidelines on metabolic and bariatric surgery]. / Interdisciplinární Evropská doporucení metabolické a bariatrické chirurgie.

In 2012, an outstanding expert panel derived from IFSO-EC (International Federation for the Surgery of Obesity - European Chapter) and EASO (European Association for the Study of Obesity), composed by key representatives of both Societies including past and present presidents together with EASOs OMTF (Obesity Management Task Force) chair, agreed to devote the joint Medico-Surgical Workshop of both institutions to the topic of metabolic surgery as a pre-satellite of the 2013 European Congress on Obesity (ECO) to be held in Liverpool given the extraordinarily advancement made specifically in this field during the past years. It was further agreed to revise and update the 2008 Interdisciplinary European Guidelines on Surgery of Severe Obesity produced in cooperation of both Societies by focusing in particular on the evidence gathered in relation to the effects on diabetes during this lustrum and the subsequent changes that have taken place in patient eligibility criteria. The expert panel composition allowed the coverage of key disciplines in the comprehensive management of obesity and obesity-associated diseases, aimed specifically at updating the clinical guidelines to reflect current knowledge, expertise and evidence-based data on metabolic and bariatric surgery.

Liver, but not adipose tissue PEDF gene expression is associated with insulin resistance.

OBJECTIVE: Recent studies linked circulating pigment epithelium-derived factor (PEDF) to obesity-associated insulin resistance, but the main source of circulating PEDF is unknown. We aimed to investigate liver and adipose tissue PEDF gene expression in association with obesity and insulin resistance. DESIGN, SUBJECTS AND METHODS: Three (two cross-sectional and one longitudinal) independent cohorts have been studied, for adipose tissue (n=80 and n=30) and liver gene expression (n=32 and n=14). Effects of high glucose and cytokines on HepG2 cell line were also investigated. PEDF gene expression and circulating PEDF were analyzed using real-time PCR and ELISA, respectively. RESULTS: In a first cohort of subjects, PEDF relative gene expression was higher in subcutaneous (SC) than in omental (OM) adipose tissue (P<0.0001) being also higher in mature adipocytes compared with stromo-vascular cells (P<0.0001). However, OM PEDF relative gene expression was decreased in morbidly obese subjects (P=0.01). Both OM PEDF and OM PEDF receptor (PEDFR) correlated positively with lipogenic and lipolytic genes, and with genes implicated in the lipid vacuole formation. Circulating PEDF levels were not associated with fat PEDF gene expression. In the second cohort, SC PEDF was decreased in subjects with type 2 diabetes and did not change significantly after weight loss. We next explored circulating PEDF in association with markers of liver-related insulin resistance injury (alanine aminotransferase, r=0.59, P=0.001). Interestingly, liver PEDF gene expression increased with obesity and insulin resistance in men, being significantly associated with fasting glucose and glycated hemoglobin in two independent cohorts. In fact, high glucose led to increased PEDF in HepG2 cells, while inflammatory stimuli present in the adipose tissue environment downregulated PEDF. CONCLUSION: Liver, but not adipose tissue, might be the source of increased circulating PEDF linked to insulin resistance.

The ghrelin O-acyltransferase-ghrelin system reduces TNF-α-induced apoptosis and autophagy in human visceral adipocytes.

AIMS/HYPOTHESIS: Proinflammatory and proapoptotic cytokines such as TNF-α are upregulated in human obesity. We evaluated the association between ghrelin isoforms (acylated and desacyl ghrelin) and TNF-α in obesity and obesity-associated type 2 diabetes, as well as the potential role of ghrelin in the control of apoptosis and autophagy in human adipocytes. METHODS: Plasma concentrations of the ghrelin isoforms and TNF-α were measured in 194 participants. Ghrelin and ghrelin O-acyltransferase (GOAT) levels were analysed by western-blot, immunohistochemistry and real-time PCR in 53 biopsies of human omental adipose tissue. We also determined the effect of acylated and desacyl ghrelin (10 to 1,000 pmol/l) on TNF-α-induced apoptosis and autophagy-related molecules in omental adipocytes. RESULTS: Circulating concentrations of acylated ghrelin and TNF-α were increased, whereas desacyl ghrelin levels were decreased in obesity-associated type 2 diabetes. Ghrelin and GOAT were produced in omental and subcutaneous adipose tissue. Visceral adipose tissue from obese patients with type 2 diabetes showed higher levels of GOAT, increased adipocyte apoptosis and increased expression of the autophagy-related genes ATG5, BECN1 and ATG7. In differentiating human omental adipocytes, incubation with acylated and desacyl ghrelin reduced TNF-α-induced activation of caspase-8 and caspase-3, and cell death. In addition, acylated ghrelin reduced the basal expression of the autophagy-related genes ATG5 and ATG7, while desacyl ghrelin inhibited the TNF-α-induced increase of ATG5, BECN1 and ATG7 expression. CONCLUSIONS/INTERPRETATION: Apoptosis and autophagy are upregulated in human visceral adipose tissue of patients with type 2 diabetes. Acylated and desacyl ghrelin reduce TNF-α-induced apoptosis and autophagy in human visceral adipocytes.

Body mass index classification misses subjects with increased cardiometabolic risk factors related to elevated adiposity.

CONTEXT: Body mass index (BMI) is widely used as a measure of overweight and obesity, but underestimates the prevalence of both conditions, defined as an excess of body fat. OBJECTIVE: We assessed the degree of misclassification on the diagnosis of obesity using BMI as compared with direct body fat percentage (BF%) determination and compared the cardiovascular and metabolic risk of non-obese and obese BMI-classified subjects with similar BF%. DESIGN: We performed a cross-sectional study. SUBJECTS: A total of 6123 (924 lean, 1637 overweight and 3562 obese classified according to BMI) Caucasian subjects (69% females), aged 18-80 years. METHODS: BMI, BF% determined by air displacement plethysmography and well-established blood markers of insulin sensitivity, lipid profile and cardiovascular risk were measured. RESULTS: We found that 29% of subjects classified as lean and 80% of individuals classified as overweight according to BMI had a BF% within the obesity range. Importantly, the levels of cardiometabolic risk factors, such as C-reactive protein, were higher in lean and overweight BMI-classified subjects with BF% within the obesity range (men 4.3 ± 9.2, women 4.9 ± 19.5 mg l(-1)) as well as in obese BMI-classified individuals (men 4.2 ± 5.5, women 5.1 ± 13.2 mg l(-1)) compared with lean volunteers with normal body fat amounts (men 0.9 ± 0.5, women 2.1 ± 2.6 mg l(-1); P<0.001 for both genders). CONCLUSION: Given the elevated concentrations of cardiometabolic risk factors reported herein in non-obese individuals according to BMI but obese based on body fat, the inclusion of body composition measurements together with morbidity evaluation in the routine medical practice both for the diagnosis and the decision-making for instauration of the most appropriate treatment of obesity is desirable.

Circulating lipopolysaccharide-binding protein (LBP) as a marker of obesity-related insulin resistance.

OBJECTIVE: Lipopolysaccharide-binding protein (LBP) is a 65-kDa acute-phase protein present in blood at high concentrations, known to be derived from the liver. We aimed to gain insights into the association of circulating LBP with insulin resistance in humans and mice. METHODS, DESIGN AND MEASUREMENTS: We studied the cross-sectional (n=222) and weight loss-induced (n=34) associations of LBP (enzyme-linked immunosorbent assay) with inflammatory and metabolic parameters (including minimal model-measured insulin sensitivity), and the effects of high-fat diet (HFD), metformin and genetic insulin sensitization (glucagon-like peptide 1 receptor knockout model) in mice. RESULTS: Circulating LBP concentration was significantly increased in subjects with type 2 diabetes and dramatically increased in subjects with morbid obesity. LBP was significantly associated with insulin sensitivity and different inflammatory markers and decreased after weight loss (22.2 ± 5.8 vs 16.2 ± 9.3 µg ml(-1), P<0.0001) in association with changes in body mass index and insulin sensitivity. Circulating LBP concentration was increased in HFD mice, whereas decreased in glucagon-like peptide 1 receptor knockout mice (significantly more insulin sensitive than wild-type mice) and after metformin administration. CONCLUSION: LBP is an inflammatory marker associated with obesity-related insulin resistance.

Association of increased visfatin/PBEF/NAMPT circulating concentrations and gene expression levels in peripheral blood cells with lipid metabolism and fatty liver in human morbid obesity.

BACKGROUND AND AIMS: Nicotinamide phosphoribosyltransferase (NAMPT) is an adipokine with physiological effects on the control of glucose homeostasis as well as potentially involved in inflammation. The association of circulating NAMPT concentrations with obesity has not been clearly established. The aim of the present work was to evaluate the effect of obesity on circulating concentrations and gene expression levels of NAMPT in human peripheral blood cells (PBCs) as well as its involvement in inflammation, glucose and lipid metabolism. METHODS AND RESULTS: Forty-four serum samples obtained from 14 lean and 30 obese volunteers were used to analyse the circulating concentrations of NAMPT. In addition, PBC, omental adipose tissue (OM) and liver biopsy samples obtained from a subgroup of subjects were used to determine transcript levels of NAMPT by Real-time PCR. Glucose and lipid profile as well as several inflammatory factors and hepatic enzymes were analysed. NAMPT circulating concentrations (P<0.01) and gene expression levels in PBC (P<0.05) were significantly increased in obese patients as compared to lean subjects. Total-cholesterol (P=0.016), HDL-cholesterol (P=0.036) and triglycerides (P=0.050) were significant and independent determinants of circulating concentrations of NAMPT (P<0.01). Moreover, a positive correlation (P<0.01) was found with the hepatic enzymes alanine aminotransferase, aspartate aminotransferase, and γ-glutamyltransferase after BMI adjustment. CONCLUSION: Our work shows that NAMPT circulating concentrations and mRNA expression levels in PBC are increased in obese patients and that plasma NAMPT levels are related to inflammation, lipid metabolism and hepatic enzymes suggesting a potential involvement in fatty liver disease and in the obesity-associated inflammatory state.