Visceral obesity and metabolic syndrome

Insulin Resistance but Not Visceral Adiposity Index Is Associated with Liver Fibrosis in Nondiabetic Subjects with Nonalcoholic Fatty Liver Disease

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is associated with obesity, type 2 diabetes mellitus, and dyslipidemia. It is well known that the presence of visceral fat increases the risk for metabolic complications of obesity, especially NAFLD. The visceral adiposity index (VAI), a novel marker of visceral fat dysfunction, shows a strong association with insulin resistance and also cardiovascular and cerebrovascular events. However, there is conflicting data regarding the association between VAI and NAFLD. Our aim was to assess the relationship between VAI, insulin resistance, adipocytokines, and liver histology, in nondiabetic subjects with NAFLD.

METHODS

A total of 215 male patients with biopsy-proven NAFLD were included. Among this group, serum levels of adiponectin, tumor necrosis factor-α (TNF-α, interleukin-6 (IL-6), and high-sensitivity C-reactive protein (hsCRP) were measured in 101 patients whose blood samples were available.

RESULTS

High gamma-glutamyl transferase (GGT), high total cholesterol (TC), high triglycerides (TGs), low high-density lipoprotein cholesterol (HDL-C), and presence of metabolic syndrome were significantly associated with higher VAI, although only higher GGT and TC were independent factors on multiple linear regression analysis. On the other hand, no significant association was found between VAI and adiponectin, TNF-α, IL-6, and hsCRP levels. The multivariate analysis of variables in patients with (n=124) and without (n=91) fibrosis showed that only higher homeostasis model assessment of insulin resistance value was independently associated with liver fibrosis.

CONCLUSIONS

Our findings suggest that VAI is not related to the severity of hepatic inflammation or fibrosis in nondiabetic patients with NAFLD. The lack of association between the adipocytokines and VAI also implies that the VAI may not be a significant indictor of the adipocyte functions.

Enhanced fatty acid oxidation in adipocytes and macrophages reduces lipid-induced triglyceride accumulation and inflammation

Lipid overload in obesity and type 2 diabetes is associated with adipocyte dysfunction, inflammation, macrophage infiltration, and decreased fatty acid oxidation (FAO). Here, we report that the expression of carnitine palmitoyltransferase 1A (CPT1A), the rate-limiting enzyme in mitochondrial FAO, is higher in human adipose tissue macrophages than in adipocytes and that it is differentially expressed in visceral vs. subcutaneous adipose tissue in both an obese and a type 2 diabetes cohort. These observations led us to further investigate the potential role of CPT1A in adipocytes and macrophages. We expressed CPT1AM, a permanently active mutant form of CPT1A, in 3T3-L1 CARΔ1 adipocytes and RAW 264.7 macrophages through adenoviral infection. Enhanced FAO in palmitate-incubated adipocytes and macrophages reduced triglyceride content and inflammation, improved insulin sensitivity in adipocytes, and reduced endoplasmic reticulum stress and ROS damage in macrophages. We conclude that increasing FAO in adipocytes and macrophages improves palmitate-induced derangements. This indicates that enhancing FAO in metabolically relevant cells such as adipocytes and macrophages may be a promising strategy for the treatment of chronic inflammatory pathologies such as obesity and type 2 diabetes.

Serum uric acid and cardiovascular risk among Portuguese adolescents

PURPOSE

The aim of the study was to investigate the association between serum uric acid (SUA) and cardiovascular risk classes (CRCs) in adolescents using a cluster-based approach.

METHODS

A cross-sectional evaluation was carried out in the 2007-2008 school year, including adolescents born in 1990 and enrolled in the schools of Porto, Portugal. The analysis included 1,286 adolescents. To identify CRC, a normal mixture model was performed including several biological cardiovascular risk factors. A multinomial logistic regression model was applied to explore the association between SUA and each CRC.

RESULTS

Three classes were extracted using model-based cluster analysis (low, medium, and high CRC). The high CRC accounted for the smallest proportion of participants (5.6%) and represented the adolescents with higher waist circumference, systolic and diastolic blood pressures, total cholesterol, triglycerides, and insulin levels. Adolescents at increased risk of cardiovascular disease had significantly higher mean concentrations of SUA compared with adolescents at low cardiovascular risk (55.0 vs. 51.5 mg/L in males and 41.9 vs. 37.6 mg/L in females). After adjustment and considering low CRC as reference, SUA was positively associated with high CRC in both sexes (odds ratio, 1.04; 95% confidence interval, 1.00-1.07 in males; and odds ratio, 1.04; 95% confidence interval, 1.01-1.07 in females).

CONCLUSIONS

Among 17-year-old adolescents, SUA increases were positively associated with higher CRC.

Purinergic signaling modulates human visceral adipose inflammatory responses: implications in metabolically unhealthy obesity

Obesity is accompanied by chronic inflammation of VAT, which promotes metabolic changes, and purinergic signaling has a key role in a wide range of inflammatory diseases. Therefore, we addressed whether fat inflammation could be differentially modulated by this signaling pathway in the MUO and in individuals who remain MHO. Our results show that the necrotized VAT of both groups released greater levels of ATP compared with lean donors. Interestingly, MUO tissue SVCs showed up-regulation and engagement of the purinergic P2X7R. The extracellular ATP concentration is regulated by an enzymatic process, in which CD39 converts ATP and ADP into AMP, and CD73 converts AMP into adenosine. In VAT, the CD73 ectoenzyme was widely distributed in immune and nonimmune cells, whereas CD39 expression was restricted to immune CD45PAN⁺ SVCs. Although the MUO group expressed the highest levels of both ectoenzymes, no difference in ATP hydrolysis capacity was found between the groups. As expected, MUO exhibited the highest NLRP3 inflammasome expression and IL-1β production. MUO SVCs also displayed up-regulation of the A2AR, allowing extracellular adenosine to increase IL-1β local secretion. Additionally, we demonstrate that metabolic parameters and BMI are positively correlated with purinergic components in VAT. These findings indicate that purinergic signaling is a novel mechanism involved in the chronic inflammation of VAT underlying the metabolic changes in obesity. Finally, our study reveals a proinflammatory role for adenosine in sustaining IL-1β production in this tissue.

Rare sugar D-psicose prevents progression and development of diabetes in T2DM model Otsuka Long-Evans Tokushima Fatty rats

BACKGROUND

The fundamental cause of overweight and obesity is consumption of calorie-dense foods. We have introduced a zero-calorie sweet sugar, d-psicose (d-allulose), a rare sugar that has been proven to have strong antihyperglycemic and antihyperlipidemic effects, and could be used as a replacement of natural sugar for the obese and diabetic subjects.

AIM

Above mentioned efficacy of d-psicose (d-allulose) has been confirmed in our previous studies on type 2 diabetes mellitus (T2DM) model Otsuka Long-Evans Tokushima Fatty (OLETF) rats with short-term treatment. In this study we investigated the long-term effect of d-psicose in preventing the commencement and progression of T2DM with the mechanism of preservation of pancreatic β-cells in OLETF rats.

METHODS

Treated OLETF rats were fed 5% d-psicose dissolved in water and control rats only water. Nondiabetic control rats, Long-Evans Tokushima Otsuka (LETO), were taken as healthy control and fed water. To follow the progression of diabetes, periodic measurements of blood glucose, plasma insulin, and body weight changes were continued till sacrifice at 60 weeks. Periodic in vivo body fat mass was measured. On sacrifice, pancreas, liver, and abdominal adipose tissues were collected for various staining tests.

RESULTS

d-Psicose prevented the commencement and progression of T2DM till 60 weeks through the maintenance of blood glucose levels, decrease in body weight gain, and the control of postprandial hyperglycemia, with decreased levels of HbA1c in comparison to nontreated control rats. This improvement in glycemic control was accompanied by the maintenance of plasma insulin levels and the preservation of pancreatic β-cells with the significant reduction in inflammatory markers. Body fat accumulation was significantly lower in the treatment group, with decreased infiltration of macrophages in the abdominal adipose tissue.

CONCLUSION

Our findings suggest that the rare sugar d-psicose could be beneficial for the prevention and control of obesity and hyperglycemia with the preservation of β-cells in the progression of T2DM.

Positive effect of exercise training at maximal fat oxidation intensity on body composition and lipid metabolism in overweight middle-aged women

The purpose of this study was to test the hypothesis that 10 weeks of supervised exercise training at the maximal fat oxidation (FATmax) intensity would improve important variables of body composition and lipid metabolism in overweight middle-aged women. A longitudinal study design was employed to evaluate the effects of FATmax exercise training. Thirty women (45-59 years old; BMI 28·2 ± 1·8 kg m(-2) ; body fat 38·9 ± 4·1%) were randomly allocated into the Exercise and Control groups, n = 15 in each group. Body composition, FATmax, predicted VO2 max, lipid profile, plasma lipoprotein lipase activity and serum leptin concentration were measured before and after the experimental period. The Exercise group was trained at the individualized FATmax intensity, 5 days per week and 1 h per day for 10 weeks. No diet control was introduced during the experimental period for all participants. Exercise group obtained significant decreases in body mass, BMI, body fat % and abdominal fat mass, as well as the concentrations of triglycerides, serum leptin and blood glucose. The activity of lipoprotein lipase was increased in trained participants. There were no changes in these variables in the Control group. In addition, there was no significant change in daily energy intake for all participants before and after the experimental period. In conclusion, the 10-week FATmax exercise training achieved improvements in body composition and lipid metabolism in overweight middle-aged women. This result suggests FATmax is an effective exercise training intensity for obesity treatment.

Adipose tissue-resident regulatory T cells: phenotypic specialization, functions and therapeutic potential

Foxp3(+)  CD4(+) regulatory T (Treg) cells, recognized to be one of the most important defences of the human body against an inappropriate immune response, have recently gained attention from those outside immunology thanks to the compelling evidence for their capability to exert non-canonical immune functions in a variety of tissues in health and disease. The recent discovery of the differences between tissue-resident Treg cells and those derived from lymphoid organs is affecting the mindset of many investigators now questioning the broad applicability of observations originally based on peripheral blood/lymphoid organ cells. So far, the best characterized 'Treg flavour' comes from studies focused on their role in suppressing adipose tissue inflammation and obesity-driven insulin resistance. Adipose tissue derived Treg cells are distinct from their counterparts in lymphoid organs based on their transcriptional profile, T-cell receptor repertoire, and cytokine and chemokine receptor expression pattern. These cells are abundant in visceral adipose tissue of lean mice but their number is greatly reduced in insulin-resistant animal models of obesity. Interestingly, peroxisome-proliferator-activated receptor γ expression by visceral adipose tissue Treg cells is crucial for their accumulation, phenotype and function in the fat and surprisingly necessary for complete restoration of insulin sensitivity in obese mice by the anti-diabetic drug Pioglitazone. This review surveys recent findings relating to the unique phenotype and function of adipose tissue-resident Treg cells, speculates on the nature of their dynamics in lean and obese mouse models, and analyses their potential therapeutic application in the treatment of type 2 diabetes.

Body composition in patients with rheumatoid arthritis is not different than healthy subjects

OBJECTIVE

Rheumatoid arthritis (RA) is associated with an increased risk of cardiovascular disease (CVD). Increased body fat, particularly its central distribution, is a well-known risk factor for CVD. A change in body composition in RA has been described previously. However, in most of these studies, age- and sex- but not body mass index (BMI)-matched controls were used. The aim of this study was to evaluate body composition in RA patients and compare it with age-, sex-, and BMI-matched controls.

MATERIAL AND METHODS

Sixty-five RA patients (55 females and 10 males; mean age 54.9 ± 10.8) and 31 healthy controls (25 females, 6 males; 53.8±8.6) were included in this study. Mean disease duration was 9.2±9.6 years. Body composition was assessed by anthropometric methods (skinfold thicknesses, body circumferences), bioimpedance analysis, and dual-energy X-ray absorptiometry (DXA). Visceral adipose tissue (VAT) was assessed with computed tomography.

RESULTS

There were no significant differences for total body fatness, regional fat distribution, and total body water and fat-free mass between RA patients and control subjects. Bone mineral content (BMC), assessed by DXA, was significantly lower in RA patients (p=0.004). Clinical disease activity indices and steroid treatment do not affect soft tissue body composition or BMC.

CONCLUSION

At least some RA patients do not have soft tissue composition alterations and may have similar health risks in comparison with subjects with similar age, sex, and total adiposity.

Inflammation and insulin/IGF-1 resistance as the possible link between obesity and neurodegeneration

Obesity is a growing epidemic that contributes to several brain disorders including Alzheimer's, Parkinson's, and Huntington's diseases. Obesity could promote these diseases through several different mechanisms. Here we review evidence supporting the involvement of two recently recognized factors linking obesity with neurodegeneration: the induction of pro-inflammatory cytokines and onset of insulin and insulin-like growth factor 1 (IGF-1) resistance. Excess peripheral pro-inflammatory mediators, some of which can cross the blood brain barrier, may trigger neuroinflammation, which subsequently exacerbates neurodegeneration. Insulin and IGF-1 resistance leads to weakening of neuroprotective signaling by these molecules and can contribute to onset of neurodegenerative diseases.

Pentraxin 3 production in the adipose tissue and the skeletal muscle in diabetic-obese mice

: Inflammation has been shown to promote obesity-induced insulin resistance. Although pentraxin (PTX) 3 is known as an anti-inflammatory factor, the effect of PTX3 on insulin sensitivity has not yet been elucidated. The aim of this study is to investigate a part of the role of PTX3 on insulin sensitivity. The authors studied the PTX3 and glucose transport protein expression levels in epididymal adipose tissue and soleus muscles of male diabetic-obese [Tsumura Suzuki obese-diabetic (TSOD)] and lean control mice. The levels of PTX3 in both skeletal muscle and adipose tissue were significantly lower in TSOD mice than in controls, and there was a significant positive correlation between them. They observed a significant positive correlation between PTX3 and glucose transport protein 4 levels in skeletal muscle. This study suggests that PTX3 may play a part of role as promoting insulin sensitivity of skeletal muscle in TSOD mice.

Size at birth and abdominal adiposity in adults: a systematic review and meta-analysis

We performed a systematic literature review on the associations between birth size and abdominal adiposity in adults, while also investigating the role of the adjustment for adult body mass index (BMI). MEDLINE, Scopus, Web of Science, LILACS and SciELO databases were searched for articles published up to February 2013. Only prospective studies were included. After screening 2,570 titles, we selected 31 publications for the narrative synthesis, of which 13 were considered to be of high methodological quality. Six main indicators of birth size were identified, and birth weight (BW) was the most extensively studied. Most studies relied on anthropometric measurements as proxies for abdominal fatness or as indicators of body fat distribution. Few studies assessed abdominal adiposity through imaging methods, generally with small sample sizes. Eleven articles could be included in the meta-analyses. BW was found to be positively associated with waist circumference in adulthood, but the association disappeared after adjustment for adult BMI. In contrast, there was no association between BW and waist-to-hip ratio, whereas a strong negative association became evident after controlling for adult BMI. In conclusion, BW seems to be associated with larger adult size in general, including both waist and hip circumferences. The marked change in coefficients after adjustment for adult BMI suggests that post-natal growth strongly affects relative central adiposity, whereas BW per se does not play a role. Given the potential impact of post-natal growth, further research is needed to identify different growth trajectories that lead to abdominal adiposity, as well as studies on interactions of foetal and post-natal growth patterns.

Fetal and neonatal exposure to nicotine leads to augmented hepatic and circulating triglycerides in adult male offspring due to increased expression of fatty acid synthase

While nicotine replacement therapy is assumed to be a safer alternative to smoking during pregnancy, the long-term consequences for the offspring remain elusive. Animal studies now suggest that maternal nicotine exposure during perinatal life leads to a wide range of adverse outcomes for the offspring including increased adiposity. The focus of this study was to investigate if nicotine exposure during pregnancy and lactation leads to alterations in hepatic triglyceride synthesis. Female Wistar rats were randomly assigned to receive daily subcutaneous injections of saline (vehicle) or nicotine bitartrate (1mg/kg/day) for two weeks prior to mating until weaning. At postnatal day 180 (PND 180), nicotine exposed offspring exhibited significantly elevated levels of circulating and hepatic triglycerides in the male offspring. This was concomitant with increased expression of fatty acid synthase (FAS), the critical hepatic enzyme in de novo triglyceride synthesis. Given that FAS is regulated by the nuclear receptor Liver X receptor (LXRα), we measured LXRα expression in both control and nicotine-exposed offspring. Nicotine exposure during pregnancy and lactation led to an increase in hepatic LXRα protein expression and enriched binding to the putative LXRE element on the FAS promoter in PND 180 male offspring. This was also associated with significantly enhanced acetylation of histone H3 [K9,14] surrounding the FAS promoter, a hallmark of chromatin activation. Collectively, these findings suggest that nicotine exposure during pregnancy and lactation leads to an increase in circulating and hepatic triglycerides long-term via changes in the transcriptional and epigenetic regulation of the hepatic lipogenic pathway.

Effects of exercise and diet composition on expression of MCP-1 and oxidative stress-related mRNA of adipose tissue in diet-induced obese mice

The aim of the study was to analyze how the expression of MCP-1, HIF-1α, NOX2, ERK1, ERK2, and Mn-SOD mRNA, which are related to inflammation and oxidative stress and which can influence the accumulation of macrophage in obese adipose tissue, differed according to a high-fat diet, change of diet composition, and exercise. Obesity was induced using a high-fat diet (45% fat) for five weeks. This investigation analyzed how the change of diet composition for eight weeks and long-term exercise training affected the expression of mRNA in epididymal white adipose tissue. For the experiment, 56 four-week-old C57BL/6 mice were used. Their epididymal white adipose tissue was extracted and used in RT-PCR analysis to find the expression level of mRNA. A high-fat diet for 13 weeks showed a significant increase in the expression of MCP-1, HIF-1α, NOX2, and ERK1 mRNA in epididymal adipose tissue. Change in diet composition and exercise decreased the expression of MCP-1, HIF-1α, NOX2, and ERK1 mRNA. Particularly, the group combining a high-fat diet and exercise had a significant increase in the expression of Mn-SOD mRNA in epididymal adipose tissue; however, it showed a significant decrease in MCP-1, HIF-1α, and NOX2. These results suggest that the antioxidant effect and weight loss by exercise decreased inflammation and oxidative stress.

Visceral adiposity in the first half of pregnancy predicts newborn weight among adolescent mothers

OBJECTIVE

Maternal obesity is a strong risk factor for gestational diabetes mellitus and fetal macrosomia. We assessed the association between maternal visceral adiposity tissue (VAT) depth in the first half of pregnancy and both glucose tolerance in late pregnancy and newborn weight in pregnant adolescents.

METHODS

We completed a prospective cohort study of 73 pregnant adolescents aged 10 to 19 years, without pre-pregnancy diabetes. VAT depth was measured by ultrasound at 12 to 20 weeks' gestation, followed by a two-hour 75-g oral glucose tolerance test at 36 to 39 weeks' gestation, to determine the glucose area under the curve (AUC glucose0-120). The association between VAT depth and newborn weight was evaluated by multiple linear regression analysis, controlling for maternal age, parity, smoking, gestational age at delivery, infant sex, pre-pregnancy BMI, weight gain in pregnancy, and fasting serum glucose at 36 to 39 weeks' gestation. The relation between VAT depth and AUC glucose0-120 was assessed by linear regression analysis, adjusting for maternal age, parity, smoking, pre-pregnancy BMI, and weight gain in pregnancy.

RESULTS

A 1 cm increase in VAT depth was associated with a 206 g (95% CI 101 to 311) adjusted increase in mean birth weight. VAT depth and the other model covariates together explained more of the variance in birth weight (r(2) = 0.282; P < 0.001) than pre-pregnancy BMI with the other covariates in the same model (r(2) = 0.081; P = 0.076). All three glucose tolerance test measures were performed at 36 to 39 weeks' gestation in 51 of the 73 participants. The relationship between VAT depth and AUC glucose0-120 was not significant (P = 0.43).

CONCLUSION

VAT depth in the first half of pregnancy predicts newborn weight better than BMI, but is not associated with glucose tolerance in late pregnancy.

Immunological mechanisms in the pathophysiology of non-alcoholic steatohepatitis

Non-alcoholic steatohepatitis (NASH) is characterized by the presence of steatosis, inflammation and hepatocyte injury and constitutes hepatic manifestation of the metabolic syndrome. The pathogenesis of NASH is complex and implicates cross-talk between different metabolically active sites, such as liver and adipose tissue. Obesity is considered a chronic low-grade inflammatory state and the liver has been recognized as being an "immunological organ". The complex role of the immune system in the pathogenesis of NASH is currently raising great interest, also in view of the possible therapeutic potential of immunotherapy in NASH. This review focuses on the disturbances of the cells constituting the innate and adaptive immune system in the liver and in adipose tissue.

Effects of running wheel training on adult obese rats programmed by maternal prolactin inhibition

The inhibition of maternal prolactin production in late lactation leads to metabolic syndrome and hypothyroidism in adult offspring. Physical training is a therapeutic strategy that could prevent or reverse this condition. We evaluated the effects of a short-duration low-intensity running wheel training program on the metabolic and hormonal alterations in rats. Lactating Wistar rats were treated with bromocriptine (Bro, 1 mg twice a day) or saline on days 19, 20, and 21 of lactation, and the training of offspring began at 35 days of age. Offspring were divided into sedentary and trained controls (C-Sed and C-Ex) and sedentary and trained Bro-treated rats (Bro-Sed and Bro-Ex). Chronic exercise delayed the onset of weight gain in Bro-Ex offspring, and the food intake did not change during the experimental period. At 180 days, visceral fat mass was higher (+46%) in the Bro-Sed offspring than in C-Sed and Bro-Ex rats. As expected, running capacity was higher in trained animals. Most parameters observed in the Bro-Sed offspring were consistent with hypothyroidism and metabolic syndrome and were reversed in the Bro-Ex group. Chronic exercise did not influence the muscle glycogen in the C-Ex group; however, liver glycogen was higher (+30%) in C-Ex group and was unchanged in both Bro offspring groups. Bro-Ex animals had higher plasma lactate dehydrogenase levels, indicating skeletal muscle damage and intolerance of the training program. Low-intensity chronic training is able to normalize many clinical aspects in Bro animals; however, these animals might have had a lower threshold for exercise adaptation than the control rats.

Regulatory T Cells Control Immune Responses through Their Non-Redundant Tissue Specific Features

Regulatory T cells (Treg) are needed in the control of immune responses and to maintain immune homeostasis. Of this subtype of regulatory lymphocytes, the most potent are Foxp3 expressing CD4+ T cells, which can be roughly divided into two main groups; natural Treg cells (nTreg), developing in the thymus, and induced or adaptive Treg cells (iTreg), developing in the periphery from naïve, conventional T cells. Both nTreg cells and iTreg cells have their own, non-redundant roles in the immune system, with nTreg cells mainly maintaining tolerance toward self-structures, and iTreg developing in response to externally delivered antigens or commensal microbes. In addition, Treg cells acquire tissue specific features and are adapted to function in the tissue they reside. This review will focus on some specific features of Treg cells in different compartments of the body.

Low dietary calcium and obesity: a comparative study in genetically obese and normal rats during early growth

PURPOSE

A low calcium intake (LCaI) may predispose to obesity, and excessive fat mass may be detrimental to bone. The impact of Ca inadequacy would be greater in subjects predisposed to obesity. LCaI effect on obesity development during the rapid growth period was compared in two strains of rats: spontaneously obese IIMb/β (O) and Wistar (W). Pregnant rats were fed 0.5% (N) or 0.2% (L) of Ca (OLCa, ONCa, WLCa and WNCa). Male pups were fed the maternal diet until day 60.

METHODS

Body composition, lipid profile, glucose homeostasis, 25 hydroxyvitamin D, Ca-phosphorus, and bone metabolism were evaluated.

RESULTS

BW and body fat were higher, whereas body protein was lower in OLCa versus ONCa (p < 0.05). OLCa presented the highest body fat, glucose, non-HDL and total cholesterol, TGL, insulin levels, and HOMA-IR, liver weight, and adipose perigonadal plus retroperitoneal pads (p < 0.05). WLCa did not exhibit an increase BW and only showed a slight change in body composition with minor biochemical alterations compared to WNCa (p < 0.05). Osteocalcin, CTX, and proximal tibia and lumbar spine BMDs were lower in O than in W rats fed the same Ca diet (p < 0.05). Body ash and Ca content, and total skeleton BMC/BW were lower in OLCa and WLCa versus their corresponding NCa groups (p < 0.05).

CONCLUSION

The negative effect of a low Ca diet on fat mass accumulation and lipid profile may be more evident in rats predisposed to obesity. Nevertheless, low CaI interferes with the normal glucose homeostasis leading to an increase in insulin resistance. Low CaI during early growth may be an obesogenic factor that may persist into adult life and may account for the development of obesity and some of its co-morbidities.

Changes in adipose tissue distribution during pregnancy in overweight and obese compared with normal weight women

OBJECTIVE

Differences in body fat distribution contribute to the metabolic abnormalities associated with overweight and obesity; however, such differences have not been adequately explored during pregnancy. Our aim was to compare longitudinal trends in maternal abdominal adipose tissue deposition during pregnancy in overweight/obese compared with normal weight women.

STUDY DESIGN

Pregnant women, classified as normal weight (body mass index (BMI) <25 kg m(-2); N=61) or overweight/obese (BMI 25 kg m(-2); N=57), were enrolled in a prospective cohort study starting in the first trimester. Maternal subcutaneous (smin) and preperitoneal (pmax) fat were measured by ultrasound at five time points starting between 6 and 10 weeks gestation. The abdominal fat index (AFI), an established marker of visceral adipose tissue, was calculated as the ratio of pmax to smin. The trajectories of smin, pmax, cumulative fat index (smin plus pmax) and the AFI across pregnancy were analyzed using mixed linear models.

RESULTS

The rate of maternal weight gain during pregnancy was significantly lower for overweight/obese women compared with their non-overweight counterparts (P<0.05). Accordingly, the rate of change of pmax and smin differed significantly in normal weight compared with overweight/obese women (P=0.0003 and 0.01, respectively). The cumulative fat index did not change across gestation in normal weight women, whereas it decreased for overweight/obese women (P=0.0005). The log AFI increased across pregnancy in both strata, but significantly more rapidly for normal weight compared with overweight/obese women (P=0.06).

CONCLUSIONS

Adipose tissue is preferentially deposited in the more metabolically active visceral compartment as pregnancy progresses. However, this process differs in normal weight compared with overweight/obese women and may contribute to metabolic differences between these groups. Our study is a step toward a more refined description of obesity and its consequences during pregnancy.

Fyn deficiency promotes a preferential increase in subcutaneous adipose tissue mass and decreased visceral adipose tissue inflammation

Previous studies have demonstrated that Fyn knockout (FynKO) mice on a standard chow diet display increased glucose clearance and whole-body insulin sensitivity associated with decreased adiposity resulting from increased fatty acid use and energy expenditure. Surprisingly, however, despite a similar extent of adipose tissue (AT) mass accumulation on a high-fat diet, the FynKO mice remained fully glucose tolerant and insulin sensitive. Physiologic analyses demonstrated that the FynKO mice had a combination of skewed AT expansion into the subcutaneous compartment rather than to the visceral depot, reduced AT inflammation associated with reduced T-cell and macrophage infiltration, and increased proportion of anti-inflammatory M2 macrophages. These data demonstrate that Fyn is an important regulator of whole-body integrative metabolism that coordinates AT expansion, inflammation, and insulin sensitivity in states of nutrient excess. These data further suggest that inhibition of Fyn function may provide a novel target to prevent AT inflammation, insulin resistance, and the dyslipidemia components of the metabolic syndrome.

Endurance exercise in a rat model of metabolic syndrome

We have measured the responses to endurance exercise training on body composition and glucose regulation, as well as cardiovascular and liver structure and function in rats fed a high carbohydrate and high fat (HCHF) diet as a model of human metabolic syndrome. Male Wistar rats (9-10 weeks old) were randomly allocated into corn starch (CS) or HCHF diet groups for 16 weeks; half of each group were exercised on a treadmill for 20, 25, and then 30 min/day, 5 days/week, during the last 8 weeks of the protocol. Metabolic, cardiovascular, and liver parameters were monitored. The HCHF diet induced symptoms of metabolic syndrome, including obesity, dyslipidemia, impaired glucose tolerance, and increased systolic blood pressure associated with the development of cardiovascular remodeling and nonalcoholic steatohepatitis. Exercise in HCHF rats decreased body mass, abdominal fat pads and circumference, blood glucose concentrations, plasma lipid profiles, systolic blood pressure, left ventricular diastolic stiffness, collagen deposition and inflammatory cell infiltration in the left ventricle, improved aortic contractile and relaxation responses, and decreased liver mass and hepatic fat accumulation. This study demonstrates that endurance exercise is effective in this rat model of diet-induced metabolic syndrome in improving body composition and glucose regulation, as well as cardiovascular and liver structure and function.

Treatment of Obesity Using GH

The obesity epidemic calls for complementary treatment possibilities in addition to lifestyle changes. One of the important regulators of lipid homeostasis is growth hormone (GH). Clinical trials have tested if GH can reduce obesity in humans. The mechanisms underlying the response to GH administration have also been investigated in animal models of human obesity. A literature search yielded 19 randomized placebo-controlled clinical studies and several animal studies investigating chronic GH treatment of obesity. Significant effects were found in some of the larger trials. One clinical trial showed significantly increased weight loss due to GH treatment, and in seven trials, a significant reduction of fat mass was found. The improvements observed were modest, but even minor improvements have been shown to be beneficial, especially if the reduction in fat mass includes visceral adipose tissue, as was reported in three of six trials. In principle, animal data support the clinical observations although the reduction of fat mass was more dramatic than observed in humans. The mechanisms resulting in lipid mobilization most likely include adipose tissue lipo-protein lipase (LPL) inhibition and antagonization of the anti-lipolytic activity of insulin. By feeding a restricted amount of a high fat diet to GH exposed rats hyper-insulinemia was avoided, loss of body fat was accelerated and metabolic markers were improved. Provision of a diet suitable for the metabolic conditions during GH treatment shows promise for improving metabolic control and can perhaps increase the efficacy and/or widen the therapeutic window of GH.

Adipokines promote lipotoxicity in human skeletal muscle cells

Studies have shown the implication of specific adipokines or fatty acids (FA) in the pathogenesis of insulin resistance. However, the interplay of adipokines with FA remains poorly understood. This study aimed to investigate the combined effects of adipokines and low concentrations of palmitic acid (PA, 100 µmol/l) on skeletal muscle metabolism. Human skeletal muscle cells were incubated with adipocyte-conditioned medium (CM), PA or PA+CM, and FA transporter and FA metabolism were analysed. CM-incubation increased CD36 level (1.8 fold) and PA-uptake (1.4 fold). However, only co-application of PA+CM resulted in profound lipid accumulation (5.3 fold), 60% reduction of PA-oxidation and 3.5 fold increased diacylglycerol content. Our results support a novel role for adipokines in the pathogenesis of T2D by increasing the lipotoxic potential of PA, notably of low concentrations. This implies an increased lipotoxic risk already at an early stage of weight gain, when lipolysis has not yet contributed to increased plasma free FA levels.

Cross-sectional and longitudinal associations between serum uric acid and metabolic syndrome

Research on the importance of serum uric acid (SUA) as a contributing metabolic factor to cardiovascular diseases has conducted to conflicting results, with most studies assuming a cross-sectional design. The aim of this study was to evaluate the association of SUA and metabolic syndrome (MetS) and its features. A representative sample of 2,485 individuals aged ≥18 years was randomly selected from the non-institutionalized resident population of Porto, Portugal. A total of 1,054 eligible subjects were included for the longitudinal analyses. Hyperuricemia was defined as SUA ≥70 mg/L in men and ≥60 mg/L in women. MetS was defined according the Joint Interim (2009) criteria. Associations were estimated using Poison regression and binomial models. In the cross-sectional analysis, subjects with hyperuricemia had a 2.10-fold increased risk of MetS as compared with normouricemic subjects (PR = 2.10, 95% CI: 1.68-2.63). Among MetS features, high triglycerides presented the strongest association with hyperuricemia (PR = 2.32, 95% CI: 1.84-2.91). The MetS crude incidence rate was 4.5/100 person-year (95% CI: 3.9-5.2) in normal uricemic and 13.0/100 person-year (95% CI: 8.5-20.0) in hyperuricemic participants. Using a multivariate longitudinal approach, hyperuricemia was positively associated with MetS incidence rate ratios (IRR = 1.73, 95% CI: 1.08-2.76). One standard deviation increase of SUA concentration was associated with a 1.22-fold increase in MetS risk (IRR = 1.22, 95% CI: 1.05-1.42). Elevated SUA presented the strongest association with high-triglycerides concentration (IRR = 1.44, 95%: 1.22-1.71) and waist circumference (IRR = 1.25, 95%: 1.05-1.49). The independent positive association between SUA and MetS suggested by this longitudinal study supports that SUA might be a risk factor for MetS.

Selection of aptamers specific for adipose tissue

Background

Obesity has reached epidemic proportions, affecting more than one tenth of the world’s population. As such, adipose tissue is being increasingly recognized as an important therapeutic target for obesity and related metabolic disorders. While many potential targets of adipose tissue have been established and drugs developed, very few of those drugs specifically target adipose tissue without affecting other tissue. This results from a limited knowledge of both cell-surface markers and physicochemical traits specific to adipocytes that might otherwise be exploited by circulating drugs.

Methodology/Principal Findings

Here we report the use of cell-SELEX technology to select two aptamers that can specifically recognize mature adipocytes: adipo-1 and adipo-8. Adipo-8 shows high affinity for differentiated, mature 3T3-L1 adipocytes with a K_d value of 17.8±5.1 nM. The binding was sustained upon incubation at 37°C and insulin stimulation, but was lost upon trypsin treatment. The binding ability was also verified on frozen tissue slides with low background fluorescence and isolated adipocytes.

Conclusions/Significance

Aptamer adipo-8 selected from a random library appears to bind to mature differentiated adipocytes specifically. This aptamer holds great promise as a molecular recognition tool for adipocyte biomarker discovery or for targeted delivery of molecules to adipocytes.

Integrative miRNA-mRNA profiling of adipose tissue unravels transcriptional circuits induced by sleep fragmentation

Obstructive sleep apnea (OSA) is a prevalent condition and strongly associated with metabolic disorders. Sleep fragmentation (SF) is a major consequence of OSA, but its contribution to OSA-related morbidities is not known. We hypothesized that SF causes specific perturbations in transcriptional networks of visceral fat cells, leading to systemic metabolic disturbances. We simultaneously profiled visceral adipose tissue mRNA and miRNA expression in mice exposed to 6 hours of SF during sleep, and developed a new computational framework based on gene set enrichment and network analyses to merge these data. This approach leverages known gene product interactions and biologic pathways to interrogate large-scale gene expression profiling data. We found that SF induced the activation of several distinct pathways, including those involved in insulin regulation and diabetes. Our integrative methodology identified putative controllers and regulators of the metabolic response during SF. We functionally validated our findings by demonstrating altered glucose and lipid homeostasis in sleep-fragmented mice. This is the first study to link sleep fragmentation with widespread disruptions in visceral adipose tissue transcriptome, and presents a generalizable approach to integrate mRNA-miRNA information for systematic mapping of regulatory networks.

Ten-year change in the association between obesity and parity: results from the National FINRISK Population Study

BACKGROUND

Overweight or weight development related to pregnancy has been associated with number of deliveries (ie, parity).

OBJECTIVE

This study evaluates 10-year changes in associations between obesity and parity.

METHODS

The data were from the National FINRISK Study on women 25-64 years of age. The study included a questionnaire and anthropometric measurements in 1997 (N = 4193) and 2007 (N = 3578). Women whose body mass index (BMI) was ≥ 30 kg/m² were considered obese, and women whose waist circumference was ≥ 88 cm were considered viscerally obese. Women with no pregnancies were categorized as nulliparous, those with 1-2 deliveries as parous, and those with ≥ 3 deliveries as multiparous. Logistic regression models were used to estimate separately the odd ratios (ORs) and 95% CIs for BMI and waist circumference. Linear regression models were used to evaluate the main effect of parity on obesity and visceral obesity.

RESULTS

Women with 1 or 2 children were less often obese (OR = 0.75; 95% CI, 0.64-0.88) or viscerally obese (OR = 0.98; 95% CI, 0.85-1.14) than nulliparous or multiparous women. Multiparous women had more visceral obesity in 2007 (OR = 1.36; 95% CI, 1.16-1.60) than other parity groups. Multiparous women had the highest BMI or waist circumference even after adjusting for age, study year, and education. The year 2007 was significantly associated with visceral obesity (OR = 2.07; 95% CI, 1.87-2.30) and obesity (OR = 1.13; 95% CI, 1.01-1.28) when compared with 1997.

CONCLUSION

Parity is an important determinant of visceral obesity, which is more prevalent in younger age groups than a decade ago. Women with ≥ 3 deliveries were more often obese or viscerally obese than other women.

Injury-induced insulin resistance in adipose tissue

Hyperglycemia and insulin resistance are common findings in critical illness. Patients in the surgical ICU are frequently treated for this 'critical illness diabetes' with intensive insulin therapy, resulting in a substantial reduction in morbidity and mortality. Adipose tissue is an important insulin target tissue, but it is not known whether adipose tissue is affected by critical illness diabetes. In the present study, a rodent model of critical illness diabetes was used to determine whether adipose tissue becomes acutely insulin resistant and how insulin signaling pathways are being affected. There was a reduction in insulin-induced phosphorylation of IR, IRS-1, Akt and GSK-3β. Since insulin resistance occurs rapidly in adipose tissue, but before the insulin resistance in skeletal muscle, it may play a role in the initial development of critical illness diabetes.

Inflammation and metabolic dysfunction: links to cardiovascular diseases

Abdominal obesity is a major risk factor for cardiovascular disease, and recent studies highlight a key role of adipose tissue dysfunction, inflammation, and aberrant adipokine release in this process. An increased demand for lipid storage results in both hyperplasia and hypertrophy, finally leading to chronic inflammation, hypoxia, and a phenotypic change of the cellular components of adipose tissue, collectively leading to a substantially altered secretory output of adipose tissue. In this review we have assessed the adipo-vascular axis, and an overview of adipokines associated with cardiovascular disease is provided. This resulted in a first list of more than 30 adipokines. A deeper analysis only considered adipokines that have been reported to impact on inflammation and NF-κB activation in the vasculature. Out of these, the most prominent link to cardiovascular disease was found for leptin, TNF-α, adipocyte fatty acid-binding protein, interleukins, and several novel adipokines such as lipocalin-2 and pigment epithelium-derived factor. Future work will need to address the potential role of these molecules as biomarkers and/or drug targets.

Effect of moderate weight loss on hepatic, pancreatic and visceral lipids in obese subjects

OBJECTIVE

To compare the effects of weight loss on visceral and subcutaneous abdominal fat, liver and pancreas lipid content and to test the effects of these changes on metabolic improvement observed after weight loss.

DESIGN

Weight-loss program designed to achieve a loss of 7-10% of the initial weight.

SUBJECTS

24 obese subjects (13 males and 11 females) with age ranging from 26 to 69 years and body mass index (BMI) 30.2-50.5 kg m(-2).

MEASUREMENTS

weight, BMI, waist circumference, body composition as assessed by dual-energy X-ray absorptiometry, metabolic variables, leptin, adiponectin, visceral and subcutaneous abdominal fat, liver and pancreas lipid content as assessed by magnetic resonance were evaluated before and after weight loss achieved by hypocaloric diet.

RESULTS

After a mean body weight decrease of 8.9%, BMI, waist circumference, fat mass, all metabolic variables, homeostasis model assessment of insulin resistance (HOMA), alanine amino transferase, gamma glutamyl transpeptidase, high-sensitivity C-reactive protein (hs-CRP) and leptin, but not adiponectin and high-density lipoprotein-cholesterol, significantly decreased (all P<0.01). Visceral and subcutaneos abdominal fat, liver and pancreas lipid content significantly decreased (all P<0.01). Percent changes in liver lipid content were greater (84.1±3%) than those in lipid pancreas content (42.3±29%) and visceral abdominal fat (31.9±15.6%). After weight loss, percentage of subjects with liver steatosis decreased from 75 to 12.5%. Insulin resistance improvement was predicted by changes in liver lipid content independently of changes in visceral fat, pancreas lipid content, systemic inflammation, leptin and gender.

CONCLUSION

Moderate weight loss determines significant decline in visceral abdominal fat, lipid content in liver and pancreas. Reduction of liver lipid content was greater than that of pancreas lipid content and visceral fat loss. Liver lipid content is the strongest predictor of insulin resistance improvement after weight loss.

Distribuição de obesidade geral e abdominal em adultos de uma cidade no Sul do Brasil

O objetivo foi determinar a prevalência e a evolução da obesidade geral e abdominal em adultos com 20 anos ou mais em Pelotas, Rio Grande do Sul, Brasil. Estudo transversal de base populacional realizado em 2010. A obesidade geral foi definida pelo índice de massa corporal (IMC) > 30kg/m² e a obesidade abdominal definida como > 88cm para mulheres e > 102cm para homens. Foram entrevistados 2.448 indivíduos. A prevalência de obesidade foi de 21,7% nos homens e 29,2% nas mulheres, já a obesidade abdominal foi de 19,5% e 37,5%, respectivamente. Na análise multivariada, menor escolaridade esteve associada ao aumento da obesidade geral e abdominal em mulheres. Renda familiar apresentou relação inversa com obesidade abdominal em homens. Comparativamente, mostraram aumento das prevalências de obesidade de 1,2 vez para as mulheres e 1,5 vez para os homens, com estudos em 1994 e 2000. Porém, para obesidade abdominal houve pequena redução entre as mulheres e se manteve semelhante para os homens. A prevalência de obesidade geral aumentou nos últimos 10 anos, enquanto que a obesidade abdominal mostrou estabilidade.

The metabolic syndrome and risk of chronic kidney disease: pathophysiology and intervention strategies

Metabolic syndrome is characterized by a clustering of cardiovascular risk factors, including abdominal obesity, elevated blood pressure and glucose concentrations, and dyslipidemia. The presence of this clinical entity is becoming more pervasive throughout the globe as the prevalence of obesity increases worldwide. Moreover, there is increased recognition of the complications and mortality related to this syndrome. This paper looks to examine the link between metabolic syndrome and the development of chronic kidney disease.

The calcium-sensing receptor affects fat accumulation via effects on antilipolytic pathways in adipose tissue of rats fed low-calcium diets

Low-calcium intake is associated with increased risk of obesity, but the mechanism underlying this is not clear. We previously reported that the calcium-sensing receptor (CaSR) plays an important role in modulating the expression of rate-limiting lipolysis enzymes in human adipocytes. In the present study, rats were fed diets containing normal [0.50% (NC)], low [0.30% (LC)], or very low [0.15% (VLC)] calcium for 15 wk. Ten rats of each group were killed at wk 5, 10, and 15 of the intervention. The LC-fed rats had greater visceral fat mass, lower serum FFA and glycerol concentrations, and greater CaSR expression in white adipose tissue than did those fed the NC diet at wk 10 and 15. Hormone-sensitive lipase (HSL) and adipose TG lipase (ATGL) protein levels were lower, whereas fatty acid synthase mRNA in white adipose tissue was greater in the LC-fed rats compared with the NC-fed rats. These differences from the NC group were greater in the VLC group than in the LC group at wk 15. In vitro experiments showed that 1,25-dihydroxycholecalciferol stimulated the expression of CaSR through the nuclear vitamin D receptor (nVDR). This resulted in an antilipolytic effect by increasing intracellular calcium, decreasing the intracellular cAMP level, and downregulating HSL and ATGL protein expression in adipocytes. These effects were suppressed by either nVDR or CaSR small-interfering RNA. These results suggest that CaSR affects fat accumulation by mediating antilipolytic pathways in adipose tissue of rats fed low-calcium diets.

The genetics of obesity and the metabolic syndrome

In this review, we discuss the genetic architecture of obesity and the metabolic syndrome, highlighting recent advances in identifying genetic variants and loci responsible for a portion of the variation in components of the metabolic syndrome, namely, adiposity traits, serum HDL and triglycerides, blood pressure, and glycemic traits. We focus particularly on recent progress from large-scale genome-wide association studies (GWAS), by detailing their successes and how lessons learned can pave the way for future discovery. Results from recent GWAS coalesce with earlier work suggesting numerous interconnections between obesity and the metabolic syndrome, developed through several potentially pleiotropic effects. We detail recent work by way of a case study on the cadherin 13 gene and its relation with adiponectin in the HyperGEN and the Framingham Heart Studies, and its association with obesity and the metabolic syndrome. We provide also a gene network analysis of recent variants related to obesity and metabolic syndrome discovered through genome-wide association studies, and 4 gene networks based on searching the NCBI database.

Bipolar disorder and metabolic syndrome: an international perspective

INTRODUCTION

The ubiquity and hazards posed by abnormal body composition and metabolic parameters in the bipolar population are a priority research and clinical issue. Herein, we summarize and synthesize international studies describing the rate of US National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III [ATP III])- and International Diabetes Federation (IDF)-defined metabolic syndrome and its criterion components in individuals with bipolar disorder.

METHODS

We conducted a PubMed search of all English-language articles published between January 2005 and July 2009 with the following search terms: metabolic syndrome and bipolar disorder, mania and manic-depression. Articles selected for review were based on adequacy of sample size, the use of standardized experimental procedures, validated assessment measures, and overall manuscript quality.

RESULTS

The rate of metabolic syndrome in individuals with bipolar disorder is increased relative to the general population. Disparate estimates are reported ranging from comparability to approximately twofold greater than the general population. The increased hazard for metabolic syndrome amongst bipolar individuals is now documented in twelve countries from Europe, Australia, Asia, North and South America. The co-occurrence of metabolic syndrome in the bipolar population is associated with a more complex illness presentation, less favourable response to treatment, and adverse course and outcome. The association between metabolic syndrome and bipolar disorder is mediated/moderated by both iatrogenic and non-iatrogenic factors.

DISCUSSION

The increased hazard for metabolic syndrome in bipolar populations is due to the clustering of traditional (and emerging) risk factors as well as iatrogenic and health systems factors. Extant data support recommendations for prioritizing, surveillance, prevention, diagnosis and management of metabolic syndrome as routine care of the bipolar patient.

Short-term weight loss in overweight/obese low-income women improves plasma zinc and metabolic syndrome risk factors

Metabolic syndrome is a group of disorders involving obesity, insulin resistance, dyslipidemia and hypertension. Obesity is the most crucial risk factor of metabolic syndrome, because it is known to precede other risk factors. Obesity is also associated with disturbances in the metabolism of the trace mineral, zinc. The overall purpose of this study was to investigate the effects of short-term weight loss on plasma zinc and metabolic syndrome risk factors. An 8-week weight loss intervention study was conducted with 90 low-income overweight/obese mothers, whose youngest child was 1-3 years old. Plasma levels of zinc, glucose, insulin, leptin, triglycerides, total, high-density lipoprotein (HDL) and low-density lipoprotein (LDL) cholesterol were measured and compared at weeks 0 and 8 of the weight loss program. At pre-study, plasma zinc was low in 39% and, within normal values in 46%, of obese/overweight mothers. By the end of intervention, plasma zinc rose by 22% and only 5% of the mothers continued to exhibit low plasma zinc. At post-study, the metabolic syndrome risk factors of waist circumference, HDL cholesterol, and diastolic blood pressure (p<0.05) showed significant improvements. Plasma zinc increased by a greater margin (67%) in women with low zinc, as compared to those with normal zinc (18%); weight reduction was similar in both the groups. Finally, changes in % body fat were related negatively with changes in plasma zinc (r=- 0.28, p<0.05). The circulating levels of zinc, as well as the metabolic syndrome components, showed significant improvements in overweight/obese low-income women after weight loss.

Polymorphisms of genes coding for ghrelin and its receptor in relation to colorectal cancer risk: a two-step gene-wide case-control study

Background

Ghrelin, an endogenous ligand for the growth hormone secretagogue receptor (GHSR), has two major functions: the stimulation of the growth hormone production and the stimulation of food intake. Accumulating evidence also indicates a role of ghrelin in cancer development.

Methods

We conducted a case-control study to examine the association of common genetic variants in the genes coding for ghrelin (GHRL) and its receptor (GHSR) with colorectal cancer risk. Pairwise tagging was used to select the 11 polymorphisms included in the study. The selected polymorphisms were genotyped in 680 cases and 593 controls from the Czech Republic.

Results

We found two SNPs associated with lower risk of colorectal cancer, namely SNPs rs27647 and rs35683. We replicated the two hits, in additional 569 cases and 726 controls from Germany.

Conclusion

A joint analysis of the two populations indicated that the T allele of rs27647 SNP exerted a protective borderline effect (P_trend = 0.004).

Insulin resistance, inflammation, and obesity: role of monocyte chemoattractant protein-1 (or CCL2) in the regulation of metabolism

To maintain homeostasis under diverse metabolic conditions, it is necessary to coordinate nutrient-sensing pathways with the immune response. This coordination requires a complex relationship between cells, hormones, and cytokines in which inflammatory and metabolic pathways are convergent at multiple levels. Recruitment of macrophages to metabolically compromised tissue is a primary event in which chemokines play a crucial role. However, chemokines may also transmit cell signals that generate multiple responses, most unrelated to chemotaxis, that are involved in different biological processes. We have reviewed the evidence showing that monocyte chemoattractant protein-1 (MCP-1 or CCL2) may have a systemic role in the regulation of metabolism that sometimes is not necessarily linked to the traffic of inflammatory cells to susceptible tissues. Main topics cover the relationship between MCP-1/CCL2, insulin resistance, inflammation, obesity, and related metabolic disturbances.

Serum lipid levels are positively associated with non-erosive reflux disease, but not with functional heartburn

BACKGROUND

Metabolic syndrome and obesity are known risk factors for gastro-esophageal reflux disease (GERD), especially for erosive esophagitis. Although non-erosive reflux disease (NERD) is probably associated with obesity or other metabolic syndrome, there is little direct evidence to support this assertion.

METHODS

Workers in Keio University who underwent a general health examination between September 2006 and August 2007 were enrolled. Reflux symptom questionnaires were administered and metabolic parameters were obtained. The severity of gastro-esophageal reflux (GER) was scored using a validated scale of videoesophagography.

KEY RESULTS

Two hundred and eighty-three subjects (243 men and 40 women; mean age 49.8 +/- 6.9 years) with no radiographic evidence of erosive esophagitis were enrolled. The severity of GER was worse among men than among women, whereas the severity of reflux symptoms was worse among women. The severity of GER was associated with age and serum triglyceride levels in men, and with the serum low-density lipoprotein cholesterol levels in women. The severity of reflux symptoms, however, was not associated with metabolic parameters. There were more women than men with reflux symptoms but without GER ('presumed' functional heartburn group), compared with subjects with neither GER nor reflux symptoms. In men, the presence of both reflux symptoms and GER ('presumed' NERD group) was associated with the serum triglyceride levels.

CONCLUSIONS & INFERENCES

While NERD is associated with serum lipid levels, functional heartburn is not. The prevalence of GER was greater among men; conversely, the prevalence of functional heartburn was greater among women.

Chemerin correlates with markers for fatty liver in morbidly obese patients and strongly decreases after weight loss induced by bariatric surgery

CONTEXT

Chemerin is a new adipokine involved in in vitro adipogenesis and insulin resistance and associates with body mass index (BMI) in vivo.

OBJECTIVE

We investigated the role of chemerin in morbid obesity, associated metabolic diseases (insulin resistance, hepatic diseases), and postsurgery-induced weight loss.

SETTING

This was a prospective study performed at a university hospital.

SUBJECTS

Subjects included 60 obese female patients (BMI 50.0 +/- 1.0 kg/m(-2)) being candidates for gastric bypass.

STUDY DESIGN

Patients were examined before and 3, 6, and 12 months after surgery. In 27 patients, chemerin was measured after 2 yr.

MAIN OUTCOME

Outcomes included chemerin, anthropometric parameters, homeostasis model assessment for insulin resistance index (HOMA-IR), cholesterol, high-density lipoprotein, triglycerides, C-reactive protein, adipokines at all time points; and liver histology and macrophage content in fat at baseline.

RESULTS

Chemerin was substantially elevated in obese patients compared with nonobese persons (353.8 +/- 18.0 vs. 191 +/- 14 ng/ml, P < 0.001). Preoperatively, chemerin concentrations correlated positively with BMI, C-reactive protein, IL-6, HOMA-IR, and the amount of omental macrophages and negatively with high-density lipoprotein levels. Baseline chemerin was elevated in patients with a significant activity score for nonalcoholic fatty liver disease, portal inflammation, fibrosis, and fibroinflammation. After surgery, chemerin decreased significantly to 253.0 +/- 14.9 ng/ml after 1 yr and pursued its decrease in patients studied for 2 yr. After surgery, chemerin concentrations positively correlated with triglycerides. The strong decrease of chemerin in the 3 months after surgery was associated with the decrease in HOMA-IR and blood glucose.

CONCLUSIONS

Chemerin concentrations are elevated in morbidly obese patients and correlated with insulin resistance and markers of liver pathology. Chemerin plasma concentrations decreased after bariatric surgery. This study suggests that chemerin might mediate metabolic alterations in obesity, drastically improving after gastric bypass.

Validation of endogenous reference genes for qRT-PCR analysis of human visceral adipose samples

Background

Given the epidemic proportions of obesity worldwide and the concurrent prevalence of metabolic syndrome, there is an urgent need for better understanding the underlying mechanisms of metabolic syndrome, in particular, the gene expression differences which may participate in obesity, insulin resistance and the associated series of chronic liver conditions. Real-time PCR (qRT-PCR) is the standard method for studying changes in relative gene expression in different tissues and experimental conditions. However, variations in amount of starting material, enzymatic efficiency and presence of inhibitors can lead to quantification errors. Hence the need for accurate data normalization is vital. Among several known strategies for data normalization, the use of reference genes as an internal control is the most common approach. Recent studies have shown that both obesity and presence of insulin resistance influence an expression of commonly used reference genes in omental fat. In this study we validated candidate reference genes suitable for qRT-PCR profiling experiments using visceral adipose samples from obese and lean individuals.

Results

Cross-validation of expression stability of eight selected reference genes using three popular algorithms, GeNorm, NormFinder and BestKeeper found ACTB and RPII as most stable reference genes.

Conclusions

We recommend ACTB and RPII as stable reference genes most suitable for gene expression studies of human visceral adipose tissue. The use of these genes as a reference pair may further enhance the robustness of qRT-PCR in this model system.