Adipose tissue dysfunction in obesity and lipodystrophy

Deciphering the Clinical Presentations in LMNA-related Lipodystrophy: Report of 115 Cases and a Systematic Review

CONTEXT

Lipodystrophy syndromes are a heterogeneous group of rare genetic or acquired disorders characterized by generalized or partial loss of adipose tissue. LMNA-related lipodystrophy syndromes are classified based on the severity and distribution of adipose tissue loss.

OBJECTIVE

We aimed to annotate all clinical and metabolic features of patients with lipodystrophy syndromes carrying pathogenic LMNA variants and assess potential genotype-phenotype relationships.

METHODS

We retrospectively reviewed and analyzed all our cases (n = 115) and all published cases (n = 379) curated from 94 studies in the literature.

RESULTS

The study included 494 patients. The most common variants in our study, R482Q and R482W, were associated with similar metabolic characteristics and complications though those with the R482W variant were younger (aged 33 [24] years vs 44 [25] years; P < .001), had an earlier diabetes diagnosis (aged 27 [18] vs 40 [17] years; P < .001) and had lower body mass index levels (24 [5] vs 25 [4]; P = .037). Dyslipidemia was the earliest biochemical evidence described in 83% of all patients at a median age of 26 (10) years, while diabetes was reported in 61% of cases. Among 39 patients with an episode of acute pancreatitis, the median age at acute pancreatitis diagnosis was 20 (17) years. Patients who were reported to have diabetes had 3.2 times, while those with hypertriglyceridemia had 12.0 times, the odds of having pancreatitis compared to those who did not.

CONCLUSION

This study reports the largest number of patients with LMNA-related lipodystrophy syndromes to date. Our report helps to quantify the prevalence of the known and rare complications associated with different phenotypes and serves as a comprehensive catalog of all known cases.

Impaired white adipose tissue fatty acid metabolism in mice fed a high-fat diet worsened by arsenic exposure, primarily affecting retroperitoneal adipose tissue

Fatty acid (FA) metabolism dysfunction of white adipose tissue (WAT) underlies obesity and insulin resistance in response to high calorie intake and/or endocrine-disrupting chemicals (EDCs), among other factors. Arsenic is an EDC that has been associated with metabolic syndrome and diabetes. However, the combined effect of a high-fat diet (HFD) and arsenic exposure on WAT FA metabolism has been little studied. FA metabolism was evaluated in visceral (epididymal and retroperitoneal) and subcutaneous WAT of C57BL/6 male mice fed control or HFD (12 and 40% kcal fat, respectively) for 16 weeks together with an environmentally relevant chronic arsenic exposure through drinking water (100 μg/l) during the second half of the study. In mice fed HFD, arsenic potentiated the increase of serum markers of selective insulin resistance in WAT and fatty acid re-esterification and the decrease in the lipolysis index. Retroperitoneal was the WAT most affected, where the combination of arsenic and HFD in contrast to HFD, generated higher weight, larger adipocytes, increased triglyceride content, and decreased fasting stimulated lipolysis evidenced by lower phosphorylation of HSL and perilipin. At the transcriptional level, arsenic in mice fed either diet downregulated genes involved in fatty acid uptake (LPL, CD36), oxidation (PPARα, CPT1), lipolysis (ADRß3) and glycerol transport (AQP7 and AQP9). Additionally, arsenic potentiated hyperinsulinemia induced by HFD, despite a slight increase in weight gain and food efficiency. Thus, the second hit of arsenic in sensitized mice by HFD worsens fatty acid metabolism impairment in WAT, mainly retroperitoneal, along with an exacerbated insulin resistance phenotype.

Adipose tissue distribution is associated with cardio-metabolic alterations in adult patients with juvenile-onset dermatomyositis

OBJECTIVES

Primary aims were to compare adipose tissue distribution in adult patients with juvenile-onset DM (JDM), with matched controls. Secondary aims were to explore how adipose tissue distribution is associated with cardio-metabolic status (cardiac dysfunction and metabolic syndrome) in patients.

METHODS

Thirty-nine JDM patients (all aged ≥18 y, mean age 31.7 y and 51% female) were examined mean 22.7 y (s.d. 8.9 y) after disease onset and compared with 39 age/sex-matched controls. In patients, disease activity and lipodystrophy were assessed by validated tools and use of prednisolone noted. In all participants, dual-energy X-ray absorptiometry (DXA) and echocardiography were used to measure visceral adipose tissue (VAT)(g) and cardiac function, respectively. Risk factors for metabolic syndrome were measured and associations with adipose tissue distribution explored. For primary and secondary aims, respectively, P-values ≤0.05 and ≤0.01 were considered significant.

RESULTS

Patients exhibited a 2.4-fold increase in VAT, and reduced HDL-cholesterol values compared with controls (P-values ≤ 0.05). Metabolic syndrome was found in 25.7% of the patients and none of the controls. Cardiac dysfunction (systolic and/or diastolic) was found in 23.7% of patients and 8.1% of controls (P = 0.07). In patients, VAT levels were correlated with age, disease duration and occurrence of metabolic syndrome and cardiac dysfunction. Occurrence of lipodystrophy (P = 0.02) and male sex (P = 0.04) tended to be independently associated with cardiac dysfunction.

CONCLUSION

Adults with JDM showed more central adiposity and cardio-metabolic alterations than controls. Further, VAT was found increased with disease duration, which was associated with development of cardio-metabolic syndrome.

The Role of Exercise, Diet, and Cytokines in Preventing Obesity and Improving Adipose Tissue

The prevalence of obesity continues to rise worldwide despite evidence-based public health recommendations. The promise to adopt a healthy lifestyle is increasingly important for tackling this global epidemic. Calorie restriction or regular exercise or a combination of the two is accepted as an effective strategy in preventing or treating obesity. Furthermore, the benefits conferred by regular exercise to overcome obesity are attributed not only to reduced adiposity or reduced levels of circulating lipids but also to the proteins, peptides, enzymes, and metabolites that are released from contracting skeletal muscle or other organs. The secretion of these molecules called cytokines in response to exercise induces browning of white adipose tissue by increasing the expression of brown adipocyte-specific genes within the white adipose tissue, suggesting that exercise-induced cytokines may play a significant role in preventing obesity. In this review, we present research-based evidence supporting the effects of exercise and various diet interventions on preventing obesity and adipose tissue health. We also discuss the interplay between adipose tissue and the cytokines secreted from skeletal muscle and other organs that are known to affect adipose tissue and metabolism.

NLR and Intestinal Dysbiosis-Associated Inflammatory Illness: Drivers or Dampers?

The intestinal microbiome maintains a close relationship with the host immunity. This connection fosters a health state by direct and indirect mechanisms. Direct influences occur mainly through the production of short-chain fatty acids (SCFAs), gastrointestinal hormones and precursors of bioactive molecules. Indirect mechanisms comprise the crosstalk between bacterial products and the host's innate immune system. Conversely, intestinal dysbiosis is a condition found in a large number of chronic intestinal inflammatory diseases, such as ulcerative colitis and Crohn's disease, as well as in diseases associated with low-grade inflammation, such as obesity, type 1 and 2 diabetes mellitus and cardiovascular diseases. NOD-Like receptors (NLRs) are cytoplasmic receptors expressed by adaptive and innate immune cells that form a multiprotein complex, termed the inflammasome, responsible for the release of mature interleukin (IL)-1β and IL-18. NLRs are also involved in the recognition of bacterial components and production of antimicrobial molecules that shape the gut microbiota and maintain the intestinal homeostasis. Recent novel findings show that NLRs may act as positive or negative regulators of inflammation by modulating NF-κB activation. This mini-review presents current and updated evidence on the interplay between NLRs and gut microbiota and their dual role, contributing to progression or conferring protection, in diabetes and other inflammatory diseases.

Senoinflammation: A major mediator underlying age-related metabolic dysregulation

Chronic inflammation is a complex and unresolved inflammatory response with low-grade multivariable patterns that aggravate systemic pathophysiological conditions and the aging process. To redefine and delineate these age-related complex inflammatory phenomena at the molecular, cellular, and systemic levels, the concept of "Senoinflammation" was recently formulated. In this review, we describe the accumulated data on both the multiphase systemic inflammatory process and the cellular proinflammatory signaling pathway. We also describe the proinflammatory mechanisms underlying the metabolic molecular pathways in aging. Additionally, we review age-related lipid accumulation, the role of the inflammatory senescence-associated secretory phenotype (SASP), the involvement of cytokine/chemokine secretion, endoplasmic reticulum (ER) stress, insulin resistance, and autophagy. The last section of the review highlights the modulation of the senoinflammatory process by the anti-aging and anti-inflammatory action of calorie restriction (CR). Evidence from aging and CR research strongly suggests that SASP from senescent cells may be the major source of secreted cytokines and chemokines during aging. A better understanding of the mechanisms underpinning the senoinflammatory response and the mitigating role of CR will provide insights into the molecular mechanisms of chronic inflammation and aging for potential interventions.

Impaired glucose transport in inguinal adipocytes after short-term high-sucrose feeding in mice

Diets enriched in sucrose severely impair metabolic regulation and are associated with obesity, insulin resistance and glucose intolerance. In the current study, we investigated the effect of 4 weeks high-sucrose diet (HSD) feeding in C57BL6/J mice, with specific focus on adipocyte function. Mice fed HSD had slightly increased adipose tissue mass but displayed similar hepatic triglycerides, glucose and insulin levels, and glucose clearance capacity as chow-fed mice. Interestingly, we found adipose depot-specific differences, where both the non- and insulin-stimulated glucose transports were markedly impaired in primary adipocytes isolated from the inguinal fat depot from HSD-fed mice. This was accompanied by decreased protein levels of both GLUT4 and AS160. A similar but much less pronounced trend was observed in the retroperitoneal depot. In contrast, both GLUT4 expression and insulin-stimulated glucose uptake were preserved in adipocytes isolated from epididymal adipose tissue with HSD. Further, we found a slight shift in cell size distribution towards larger cells with HSD and a significant decrease of ACC and PGC-1α expression in the inguinal adipose tissue depot. Moreover, fructose alone was sufficient to decrease GLUT4 expression in cultured, mature adipocytes. Altogether, we demonstrate that short-term HSD feeding has deleterious impact on insulin response and glucose transport in the inguinal adipose tissue depot, specifically. These changes occur before the onset of systemic glucose dysmetabolism and therefore could provide a mechanistic link to overall impaired energy metabolism reported after prolonged HSD feeding, alone or in combination with HFD.

Changes in redox and endoplasmic reticulum homeostasis are related to congenital generalized lipodystrophy type 2

CGL type 2 is a rare autosomal recessive syndrome characterized by an almost complete lack of body fat. CGL is caused by loss-of-function mutations in both alleles of the BSCL2 gene that codifies to seipin. Subjects often show hyperglycemia, decreased HDL-c, and hypoadiponectinemia. These laboratory findings are important triggers for changes in redox and ER homeostasis. Therefore, our aim was to investigate whether these intracellular mechanisms are associated with this syndrome. We collected blood from people from Northeastern Brazil with 0, 1, and 2 mutant alleles for the rs786205071 in the BSCL2 gene. Through the qPCR technique, we evaluated the expression of genes responsible for triggering the antioxidant response, DNA repair, and ER stress in leukocytes. Colorimetric tests were applied to quantify lipid peroxidation and to evaluate the redox status of glutathione, as well as to access the panorama of energy metabolism. Long extension PCR was performed to observe leukocyte mitochondrial DNA lesions, and the immunoblot technique to investigate plasma adiponectin concentrations. Subjects with the rs786205071 in both BSCL2 alleles showed increased transcription of NFE2L2, APEX1, and OGG1 in leukocytes, as well as high concentrations of malondialdehyde and the GSSG:GSH ratio in plasma. We also observed increase of mitochondrial DNA lesions and XBP1 splicing, as well as a decrease in adiponectin and HDL-c. Our data suggest the presence of lipid lesions due to changes in redox homeostasis in that group, associated with increased levels of mitochondrial DNA damage and transcriptional activation of genes involved with antioxidant response and DNA repair.

Adult-Onset Diseases in Low Birth Weight Infants: Association with Adipose Tissue Maldevelopment

Low birth weight (LBW) infants have higher risk of developing insulin resistance and its comorbidities later in life. The concept of “developmental origins of health and disease” suggests that intrauterine and postnatal environments have an important role in increasing these risks. The risk of such adult-onset diseases in LBW infants might be associated with adipose tissue maldevelopment including altered body composition and increased amount of visceral fat, which is the same mechanism as that in children and adults with metabolic syndrome. However, LBW infants often have different characteristics: they are not always overweight or obese over their life course. The inconsistency might be associated with the thrifty phenotype, which is produced in response to impaired growth potential and decreased lean body mass. LBW infants tend to be obese within the limits of impaired growth potential. Through our previous investigations evaluating longitudinal changes in adiponectin levels at an early stage of life, we speculated that probably, the intrauterine life of term infants or the period up to term-equivalent age in preterm infants might be the key age for the development of adipose tissues including fat cells. Because of that, we hypothesized that the smaller number of adipocytes in LBW infants might be associated with overloading of single adipocytes and impaired adipose tissue expandability. The possible mechanisms are discussed from the perspective of adipose tissue maldevelopment in LBW infants.

Notoginsenoside Fe suppresses diet induced obesity and activates paraventricular hypothalamic neurons

Obesity has become a major public health challenge worldwide. Energy imbalance between calorie acquisition and consumption is the fundamental cause of obesity. Notoginsenoside Fe is a naturally occurring compound in Panax notoginseng, a herb used in the treatment of cardiovascular diseases in traditional Chinese medicine. Here, we evaluated the effect of notoginsenoside Fe on obesity development induced by high-fat diet in C57BL/6 mice. Our results demonstrated that notoginsenoside Fe decreased food intake and body weight, as well as protected liver structure integrity and normal function. Metabolic cage analysis showed that notoginsenoside Fe also promoted resting metabolic rate. In addition, intracerebroventricular (i.c.v) injection of notoginsenoside Fe induced C-Fos expression in the paraventricular nucleus (PVH) but not the arcuate nucleus (ARC) of the hypothalamus. These results suggest that Fe may reduce body weight through the activation of energy-sensing neurons in the hypothalamus.

Notoginsenoside Fe, a naturally occurring compound in Panax notoginseng, significantly reduces body weight, promotes metabolic rate, and suppresses food intake through activating C-Fos expression in PVH in high-fat diet induced obese mice.

Transgenic Mice Overexpressing SREBP-1a in Male ob/ob Mice Exhibit Lipodystrophy and Exacerbate Insulin Resistance

Sterol regulatory element-binding protein (SREBP)-1a is a key transcription factor that activates the expression of genes involved in the synthesis of fatty acids, triglycerides (TGs), and cholesterol. Transgenic mice that overexpress the nuclear form of SREBP-1a under the control of the phosphoenolpyruvate carboxykinase promoter (Tg-1a) were previously shown to display a lipodystrophic phenotype characterized by enlarged and fatty livers, diminished peripheral white adipose tissue (WAT), and insulin resistance. In the current study, we crossed these Tg-1a mice with genetically obese (ob/ob) mice (Tg-1a;ob/ob) and examined change in fat distribution between liver and adipose tissues in severe obesity and mechanism underlying the lipodystrophic phenotype in mice with Tg-1a. Tg-1a;ob/ob mice developed more severe steatohepatitis but had reduced WAT mass and body weight compared with ob/ob mice. The reduction of WAT mass in Tg-1a and Tg-1a;ob/ob mice was accompanied by enhanced lipogenesis and lipid uptake in the liver, reduced plasma lipid levels, impaired adipocyte differentiation, reduced food intake, enhanced energy expenditure, and extended macrophage infiltration and fibrosis in WAT. Despite the improved glucose tolerance, Tg-1a;ob/ob mice showed severe peripheral insulin resistance. Adenoviral hepatic expression of SREBP-1a mimicked these phenotypes. The "fat steal"-like lipodystrophy phenotype of the Tg-1a;ob/ob model demonstrates that hepatic SREBP-1a activation has a strong impact on the partition of TG accumulation, resulting in adipose-tissue remodeling by inflammation and fibrosis and insulin resistance.

Molecular mechanisms of the anti-obesity effect of bioactive ingredients in common spices: a review

The mechanisms of the anti-obesity effects of bioactive compounds in common spices in adipocytes, animal models and human participants have been reviewed.

Spontaneous development of hepatosteatosis in perilipin-1 null mice with adipose tissue dysfunction

Fatty liver features triglyceride accumulation in hepatocytes and often occurs with obesity and lipodystrophy in humans. Here, we investigated the mechanism of maladaptive hepatosteatosis with adipose-tissue dysfunction. Perilipin 1 (Plin1) did not exist in hepatocytes but was expressed exclusively in adipocytes as a dual modulator for regulating two principal adipose-tissue functions, triglyceride storage and breakdown. Plin1-/- mice showed decreased fat storage but increased lipolysis and efflux of fatty acids from adipose tissue, and hepatosteatosis spontaneously developed without altered circulating inflammatory adipocytokine levels. Plin1-/- adipose dysfunction impaired insulin sensitivity and hepatic glucose metabolism, which might inhibit gluconeogenesis to produce more intermediates for hepatic lipid synthesis. Indeed, the livers of Plin1-/- mice exhibited upregulated mRNA and protein expression of key enzymes and transcriptional factors for the uptake and transport of fatty acids and for de novo synthesis of triglycerides, but the expression of key enzymes and transcriptional factors for fatty-acid oxidation was downregulated. Biochemical assays in Plin1-/- mice confirmed increased fatty acid synthase activity but decreased activity of mitochondrial carnitine palmitoyltransferase 1 and [³H]-palmitate oxidation in the liver. We concluded that dysregulation of two principal functions, adipose storage and hydrolysis, had deleterious consequences on the hepatic lipid metabolism and thereby caused maladaptive hepatosteatosis. This mouse model might mimic and explain the pathogenesis of hepatosteatosis occurring in two typical disorders of adipose tissue dysfunction, obesity and lipodystrophy, particularly in lipodystrophic patients with Plin1 mutation.

FPLD2 LMNA mutation R482W dysregulates iPSC-derived adipocyte function and lipid metabolism

Lipodystrophies are disorders that directly affect lipid metabolism and storage. Familial partial lipodystrophy type 2 (FPLD2) is caused by an autosomal dominant mutation in the LMNA gene. FPLD2 is characterized by abnormal adipose tissue distribution. This leads to metabolic deficiencies, such as insulin-resistant diabetes mellitus and hypertriglyceridemia. Here we have derived iPSC lines from two individuals diagnosed with FPLD2, and differentiated these cells into adipocytes. Adipogenesis and certain adipocyte functions are impaired in FPLD2-adipocytes. Consistent with the lipodystrophic phenotype, FPLD2-adipocytes appear to accumulate markers of autophagy and catabolize triglycerides at higher levels than control adipocytes. These data are suggestive of a mechanism causing the lack of adipose tissue in FPLD2 patients.

Obesity-alleviating potential of asiatic acid and its effects on ACC1, UCP2, and CPT1 mRNA expression in high fat diet-induced obese Sprague-Dawley rats

The present study evaluated the effects of asiatic acid (AA), a pentacyclic triterpenoid from Centella asiatica on lipid metabolism parameters in a rat model of obesity induced using a high fat diet (HFD) for 42 days. AA (20 mg/kg body weight [BW]) was administered orally once daily for 42 days, and an orlistat-treated group of rats (10 mg/kg BW) was included for comparison. Changes in BW, blood glucose levels, insulin resistance and leptin, adiponectin, amylase, and lipase levels in the blood; lipid profiles of plasma; liver antioxidants levels; and acetyl CoA carboxylase(ACC), uncoupling protein-2 (UCP2), and carnitine palmitoyltransferase-1 (CPT1) mRNA expression were observed in the experimental rats. Our results revealed that AA (20 mg/kg BW), similar to orlistat, reduced the increase in BW; increased bone mineral contents and bone mineral densities; reduced blood glucose levels, insulin resistance, leptin, plasma lipid levels; increased adiponectin, amylase, lipase levels in the blood; showed antioxidant activity; and altered mRNA expression of lipid metabolism-related genes, including ACC, UCP 2, and CPT 1, in the HFD-fed rats. From these results, we concluded that AA possesses significant anti-obesity potential through the suppression of BW gain, lipid lowering action, development of insulin and leptin sensitivity, antioxidant activity, and increased mRNA expression of lipid metabolism-related genes.

Visceral adiposity index and 10-year cardiovascular disease incidence: The ATTICA study

BACKGROUND AND AIMS

Visceral adiposity index (VAI) has been proposed as a marker of visceral adipose tissue accumulation/dysfunction. Our aim was to evaluate potential associations between the VAI and the 10-year cardiovascular disease (CVD) incidence.

METHODS AND RESULTS

During 2001-2002, 3042 Greek adults (1514 men; age: ≥18 years) without previous CVD were recruited into the ATTICA study, whilst the 10-year study follow-up was performed in 2011-2012, recording the fatal/non-fatal CVD incidence in 2020 (1010 men) participants. The baseline VAI scores for these participants were calculated based on anthropometric and lipid variables, while VAI tertiles were extracted for further analyses. During the study follow-up a total of 317 CVD events (15.7%) were observed. At baseline, the participants' age and the prevalence of hypertension, diabetes, hypercholesterolemia and metabolic syndrome increased significantly across the VAI tertiles. After adjusting for multiple confounders, VAI exhibited a significantly independent positive association with the 10-year CVD incidence (OR = 1.05, 95%CI: 1.01, 1.10), whereas the association of the body mass index (HR = 1.03, 95%CI: 0.99, 1.08), or the waist circumference (HR = 1.01, 95%CI: 0.99, 1.02) was less prominent. Sex-specific analysis further showed that VAI remained significantly predictive of CVD in men alone (HR = 1.06, 95%CI: 1.00, 1.11) but not in women (HR = 1.06, 95%CI: 0.96, 1.10).

CONCLUSIONS

Our findings show for the first time in a large-sample, long-term, prospective study in Europe that the VAI is independently associated with elevated 10-year CVD risk, particularly in men. This suggests that the VAI may be utilized as an additional indicator of long-term CVD risk for Caucasian/Mediterranean men without previous CVD.

Ethanolic Fraction of Terminalia tomentosa Attenuates Biochemical and Physiological Derangements in Diet Induced Obese Rat Model by Regulating Key Lipid Metabolizing Enzymes and Adipokines

The prevalence of overweight-obesity and associated comorbidities have reached alarming levels necessitating the need to explore effective therapeutics. In the present work, we demonstrated the promising antiobesity activity of ethanolic fraction of Terminalia tomentosa bark (EFTT) in diet induced obese rat model. High Fat Diet (HFD)-fed obese rats were orally administered with EFTT (50, 100 and 200 mg/kg body weight). Changes in body weight, body composition, bone mineral concentration, bone mineral density, plasma glucose, insulin, leptin, adiponectin, circulatory and tissue lipid profiles, and the activities of liver antioxidant enzymes, key lipid metabolic enzymes and mRNA expressions of fatty acid synthase (FAS), peroxisome proliferator-activated receptor gamma (PPAR-γ), leptin and tumor necrosis factor alpha (TNF-α) were assessed in experimental rats in the presence and absence of EFTT. At a dose of 200 mg/kg b.wt, EFTT has substantially attenuated body weight and related patho-physiological alterations in HFD-induced obese rats. These findings were correlated with histological observations of adipose tissue. The therapeutic activity of EFTT could be possibly through restoration of antioxidants status, regulation of key lipid metabolizing enzymes, expression of FAS, leptin, PPAR-γ and by synchronized control of energy metabolism in liver and adipose tissue.

Divergent relationship of circulating CTRP3 levels between obesity and gender: a cross-sectional study

C1q TNF Related Protein 3 (CTRP3) is a novel adipose tissue derived secreted factor, or adipokine, which has been linked to a number of beneficial biological effects on metabolism, inflammation, and survival signaling in a variety of tissues. However, very little is known about CTRP3 in regards to human health. The purpose of this project was to examine circulating CTRP3 levels in a clinical population, patients with symptoms requiring heart catheterization in order to identify the presence of obstructive coronary artery disease (CAD). It was hypothesized that serum CTRP3 levels would be decreased in the presence of CAD.

Serum adiponectin in HIV-1 and hepatitis C virus mono- and co-infected Kenyan injection drug users

Adiponectin is an important marker of anthropometric profiles of adipose tissue. However, association of adiponectin and adiposity in HIV mono- and co-infected and hepatitis (HCV) injection drug users (IDUs) has not been elucidated. Therefore, the relationship of total adiponectin levels with anthropometric indices of adiposity was examined in HIV mono-infected (anti-retroviral treatment, ART-naive, n=16 and -experienced, n=34); HCV mono-infected, n=36; HIV and HCV co-infected (ART-naive, n=5 and -experienced, n=13); uninfected, n=19 IDUs; and healthy controls, n=16 from coastal Kenya. Anthropometric indices of adiposity were recorded and total circulating adiponectin levels were measured in serum samples using enzyme-linked immunosorbent assay. Adiponectin levels differed significantly amongst the study groups (P<0.0001). Post-hoc analyses revealed decreased levels in HIV mono-infected ART-naive IDUs in comparison to uninfected IDUs (P<0.05) and healthy controls (P<0.05). However, adiponectin levels were elevated in HCV mono-infected IDUs relative to HIV mono-infected ART-naive (P<0.001) and -experienced (P<0.001) as well as HIV and HCV co-infected ART-naive (P<0.05) IDUs. Furthermore, adiponectin correlated with weight (ρ=0.687; P=0.003) and BMI (ρ=0.598; P=0.014) in HIV mono-infected ART-naive IDUs; waist circumference (ρ=-0.626; P<0.0001), hip (ρ=-0.561; P=0.001) circumference, and bust-to-waist ratio (ρ=0.561; P=0.001) in HIV mono-infected ART-experienced IDUs; waist girth (ρ=0.375; P=0.024) in HCV mono-infected IDUs; and waist-to-hip ratio (ρ=-0.872; P=0.048) in HIV and HCV co-infected ART-naive IDUs. Altogether, these results suggest suppression of adiponectin production in treatment-naive HIV mono-infected IDUs and that circulating adiponectin is a useful surrogate marker of altered adiposity in treatment-naive and -experienced HIV and HCV mono- and co-infected IDUs.

Obesity, insulin resistance and comorbidities? Mechanisms of association

Overall excess of fat, usually defined by the body mass index, is associated with metabolic (e.g. glucose intolerance, type 2 diabetes mellitus (T2DM), dyslipidemia) and non-metabolic disorders (e.g. neoplasias, polycystic ovary syndrome, non-alcoholic fat liver disease, glomerulopathy, bone fragility etc.). However, more than its total amount, the distribution of adipose tissue throughout the body is a better predictor of the risk to the development of those disorders. Fat accumulation in the abdominal area and in non-adipose tissue (ectopic fat), for example, is associated with increased risk to develop metabolic and non-metabolic derangements. On the other hand, observations suggest that individuals who present peripheral adiposity, characterized by large hip and thigh circumferences, have better glucose tolerance, reduced incidence of T2DM and of metabolic syndrome. Insulin resistance (IR) is one of the main culprits in the association between obesity, particularly visceral, and metabolic as well as non-metabolic diseases. In this review we will highlight the current pathophysiological and molecular mechanisms possibly involved in the link between increased VAT, ectopic fat, IR and comorbidities. We will also provide some insights in the identification of these abnormalities.

Expression of seipin in adipose tissue rescues lipodystrophy, hepatic steatosis and insulin resistance in seipin null mice

OBJECTIVES

Gene mutations in an ER protein seipin result in congenital generalized lipodystrophy (CGL) in humans, accompanied with hepatic steatosis and insulin resistance. Seipin gene is highly expressed in the brain, testis and adipose tissue. Seipin globally deficient mice (SKO) displayed similar phenotypes as human counterparts. It has been demonstrated that adipose-specific seipin knockout mice at elder age were indistinguishable from SKO mice. Due to the large mass of adipose tissue in the body, we hypothesized that seipin in adipose tissue might be responsible for the multiple metabolism-related abnormalities in SKO mice.

METHODS AND RESULTS

Transgenic mice with adipose-specific expression of human seipin gene driven by aP2 promoter were generated and crossed with SKO mice to obtain adipose-specific seipin reconstitute (Seipin-RE) mice. In comparison with wild-type (WT) and SKO mice, the Seipin-RE mice exhibited normal plasma triglyceride and non-esterified fatty acids upon fasting, recovered adipose tissue mass, restored epididymal and subcutaneous fat pads morphology and partially recovered plasma leptin and adiponectin levels. Moreover, hepatic steatosis and insulin resistance was also absent in these mice.

CONCLUSION

Our study demonstrates that expression of seipin in adipose tissue alone could rescue dyslipidemia, lipodystrophy, hepatic steatosis and insulin resistance in SKO mice.

Defective differentiation of adipose precursor cells from lipodystrophic mice lacking perilipin 1

Perilipin 1 (Plin1) localizes at the surface of lipid droplets to regulate triglyceride storage and hydrolysis in adipocytes. Plin1 defect leads to low adiposity in mice and partial lipodystrophy in human. This study investigated the roles of Plin1 in adipocyte differentiation. Plin1 null (-/-) mice showed plenty of multilocular adipocytes and small unilocular adipocytes in adipose tissue, along with lack of a subpopulation of adipose progenitor cells capable of in vivo adipogenesis and along with downregulation of adipogenic pathway. Before initiation of differentiation, adipose stromal-vascular cells (SVCs) from Plin1-/- mice already accumulated numerous tiny lipid droplets, which increased in number and size during the first 12-h induction but thereafter became disappeared at day 1 of differentiation. The adipogenic signaling was dysregulated despite protein level of PPARγ was near normal in Plin1-/- SVCs like in Plin1-/- adipose tissue. Heterozygous Plin1+/- SVCs were able to develop lipid droplets, with both the number and size more than in Plin1-/- SVCs but less than in Plin1+/+ SVCs, indicating that Plin1 haploinsufficiency accounts for attenuated adipogenesis. Aberrant lipid droplet growth and differentiation of Plin1-/- SVCs were rescued by adenoviral Plin1 expression and were ameliorated by enhanced or prolonged adipogenic stimulation. Our finding suggests that Plin1 plays an important role in adipocyte differentiation and provides an insight into the pathology of partial lipodystrophy in patients with Plin1 mutation.

Lipin Family Proteins - Key Regulators in Lipid Metabolism

Background: Proteins in the lipin family play a key role in lipid synthesis due to their phosphatidate phosphatase activity, and they also act as transcriptional coactivators to regulate the expression of genes involved in lipid metabolism. The lipin family includes three members, lipin1, lipin2, and lipin3, which exhibit tissue-specific expression, indicating that they may have distinct roles in mediating disease. To date, most studies have focused on lipin1, whereas the roles of lipin2 and lipin3 are less understood. Summary: This review introduces the structural characteristics, physiological functions, relationship to lipid metabolism, and patterns of expression of the lipin family proteins, highlighting their roles in lipid metabolic homeostasis. © 2014 S. Karger AG, Basel

Anti-obesity action of gingerol: effect on lipid profile, insulin, leptin, amylase and lipase in male obese rats induced by a high-fat diet

BACKGROUND

Obesity represents a rapidly growing threat to the health of populations and diet intervention has been proposed as one of the strategies for weight loss. Ginger and its constituents have been used for their anti-flatulent, expectorant and appetising properties and they are reported to possess gastro-protective and cholesterol-lowering properties. The present study investigated the effects of gingerol on the changes in body weight, serum glucose, insulin, insulin resistance and lipid profile in plasma and liver as well as on the activity of amylase, lipase and leptin in high-fat diet (HFD)-induced obese rats.

RESULTS

HFD-induced obese rats were treated orally with gingerol (25, 50 and 75 mg kg(-1) ) once daily for 30 days. A lorcaserin-treated group (10 mg kg(-1) ) was included for comparison. The levels of body weight, glucose, lipid profile and insulin, insulin resistance, leptin, amylase and lipase were increased significantly (P < 0.05) in HFD rats. Rats treated with gingerol and fed a HFD showed significantly (P < 0.05) decreased glucose level, body weight, leptin, insulin, amylase, lipase plasma and tissue lipids when compared to normal control. The effect at a dose of 75 mg kg(-1) of gingerol was more pronounced than that of the dose 25 mg kg(-1) and 50 mg kg(-1) . The lorcaserin-treated group also manifested similar effects to those of gingerol.

CONCLUSION

These findings suggested that ginger supplementation suppresses obesity induced by a high fat diet and it might be a promising adjuvant therapy for the treatment of obesity and its complications.

The impact of ageing on adipose structure, function and vasculature in the B6D2F1 mouse: evidence of significant multisystem dysfunction

The critical influence of the white adipose tissue (WAT) on metabolism is well-appreciated in obesity, but adipose tissue dysfunction as a mechanism underlying age-associated metabolic dysfunction requires elucidation. To explore this possibility, we assessed metabolism and measures of epididymal (e)WAT mitochondria and artery function in young (6.1 ± 0.4 months) and old (29.6 ± 0.2 months) B6D2F1 mice. There were no group differences in average daily oxygen consumption, fasted blood glucose or plasma free fatty acids, but fasted plasma insulin and the homeostatic model assessment of insulin resistance (HOMA-IR%) were higher in the old (∼50-85%, P < 0.05). Tissue mass (P < 0.05) and adipocyte area were lower (∼60%) (P < 0.01) and fibrosis was greater (sevenfold, P < 0.01) in eWAT with older age. The old also exhibited greater liver triglycerides (∼60%, P < 0.05). The mitochondrial respiratory oxygen flux after the addition of glutamate and malate (GM), adenosine diphosphate (d), succinate (S) and octanoyl carnitine (O) were one- to twofold higher in eWAT of old mice (P < 0.05). Despite no change in the respiratory control ratio, substrate control ratios of GMOd/GMd and GMOSd/GMd were ∼30-40% lower in old mice (P < 0.05) and were concomitant with increased nitrotyrosine (P < 0.05) and reduced expression of brown adipose markers (P < 0.05). Ageing reduced vascularity (∼50%, P < 0.01), angiogenic capacity (twofold, P < 0.05) and expression of vascular endothelial growth factor (∼50%, P < 0.05) in eWAT. Finally, endothelium-dependent dilation was lower (P < 0.01) in isolated arteries from eWAT arteries of the old mice. Thus, metabolic dysfunction with advancing age occurs in concert with dysfunction in the adipose tissue characterized by both mitochondrial and arterial dysfunction.

Visceral adiposity index (VAI) is predictive of an altered adipokine profile in patients with type 2 diabetes

Aims

Although there is still no clear definition of “adipose tissue dysfunction” or ATD, the identification of a clinical marker of altered fat distribution and function may provide the needed tools for early identification of a condition of cardiometabolic risk. Our aim was to evaluate the correlations among various anthropometric indices [BMI, Waist Circumference (WC), Hip Circumference (HC), Waist/Hip ratio (WHR), Body Adiposity Index (BAI) and Visceral adiposity Index (VAI)] and several adipocytokines [Visfatin, Resistin, Leptin, Soluble leptin receptors (sOB-R), Adiponectin, Ghrelin, Adipsin, PAI-1, vascular endothelial growth factor (VEGF), Hepatocyte growth factor (HGF) TNF-α, hs-CRP, IL-6, IL-18] in patients with type 2 diabetes (DM2).

Materials and Methods

Ninety-one DM2 patients (age: 65.25±6.38 years; 42 men and 49 women) in stable treatment for the last six months with metformin in monotherapy (1.5–2 g/day) were cross-sectionally studied. Clinical, anthropometric, and metabolic parameters were evaluated. Serum adipocytokine levels were assayed with Luminex based kits.

Results

At the Pearson’s correlation, among all the indices investigated, VAI showed a significant correlation with almost all adipocytokines analyzed [Visfatin, Resistin and hsCRP (all p<0.001); Adiponectin, sOb-R, IL-6, IL-18, HGF (all p<0.010); Ghrelin and VEGF (both p<0.05)]. Through a two-step cluster analysis, 55 patients were identified with the most altered adipocytokine profile (patients with ATD). At a ROC analysis, VAI showed the highest C-statistic [0.767 (95% CI 0.66–0.84)] of all the indices.

Conclusions

Our study suggests that the VAI, among the most common indexes of adiposity assessment, shows the best correlation with the best known adipocytokines and cardiometabolic risk serum markers. Although to date we are still far from clearly identifying an ATD, the VAI would be an easy tool for clearly mirroring a condition of cardiometabolic risk, in the absence of an overt metabolic syndrome.

Adipose tissue depot and cell size dependency of adiponectin synthesis and secretion in human obesity

Adiponectin is an insulin sensitizing fat cell (FC) hormone whose levels are related to adipose tissue (AT) mass and depot distribution. We hypothesized that the nature of AT expansion (hypertrophy vs. hyperplasia) contributes to obesity-related reductions in serum adiponectin and that this effect is influenced by the regional distribution of AT to subcutaneous (S) and visceral (V) depots. Thirteen obese subjects provided paired AT biopsies. Serum total and high molecular weight (HMW) adiponectin levels were determined by ELISA. Secretion was quantified following 24-h explant culture. FC size, number, % large, and % small FC were determined by microscopic analysis. Secretion of total adiponectin was highest by SAT (P = 0.008) and correlated more strongly with serum adiponectin (total: P = 0.015, r = 0.77; HMW: P = 0.005, r = 0.83) than did secretion by VAT (P = 0.05, r = 0.66 for both). FC size was greatest in SAT and correlated negatively with both serum (total: P = 0.01, r = −0.74; HMW: P = 0.03, r = −0.69) and secreted (total: P = 0.05, r = −0.72; HMW: P = 0.02, r = −0.87) adiponectin. The % small FC in SAT correlated positively with both serum (total: P = 0.006, r = 0.87; HMW: P = 0.009, r = 0.79) and secreted (total: P = 0.03, r = 0.75; HMW: P = 0.01, r = 0.92) adiponectin. VAT FC size correlated negatively with serum HMW adiponectin (P = 0.01, r = −0.76) but not with any measure of secretion. VAT had the greatest % small FC, which related positively to serum HMW (P = 0.004, r = 0.81) and to secreted total adiponectin (P = 0.02, r = 0.78). These studies indicate that differences in fat cell size and depot distribution of AT expansion are important influences on adiponectin in obesity.

Polycystic ovarian syndrome in patients with lipodystrophy: Report of 2 cases with review of literature

Lipodystrophy is a clinical disorder characterized by maldistribution of body fat. Hyperinsulinemia, insulin resistance, and abnormalities of glucose homeostasis are commonly described among these patients. Hyperinsulinemia is also involved in the pathogenesis of polycystic ovarian syndrome, a condition, described rarely in patients with lipodystrophy. Here, we describe 2 females of partial lipodystrophy who presented with features of polycystic ovarian disease. Both had severe hyperinsulinemia and irregular periods, one had hyperandrogenism and hirsuitism while the other was non-hirsuite.

Experimental hyperthyroidism decreases gene expression and serum levels of adipokines in obesity

Aims. To analyze the influence of hyperthyroidism on the gene expression and serum concentration of leptin, resistin, and adiponectin in obese animals. Main Methods. Male Wistar rats were randomly divided into two groups: control (C)—fed with commercial chow ad libitum—and obese (OB)—fed with a hypercaloric diet. After group characterization, the OB rats continued receiving a hypercaloric diet and were randomized into two groups: obese animals (OB) and obese with 25 μg triiodothyronine (T₃)/100 BW (OT). The T₃ dose was administered every day for the last 2 weeks of the study. After 30 weeks the animals were euthanized. Samples of blood and adipose tissue were collected for biochemical and hormonal analyses as well as gene expression of leptin, resistin, and adiponectin. Results. T₃ treatment was effective, increasing fT₃ levels and decreasing fT₄ and TSH serum concentration. Administration of T₃ promotes weight loss, decreases all fat deposits, and diminishes serum levels of leptin, resistin, and adiponectin by reducing their gene expression. Conclusions. Our results suggest that T₃ modulate serum and gene expression levels of leptin, resistin, and adiponectin in experimental model of obesity, providing new insights regarding the relationship between T₃ and adipokines in obesity.

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.

Polycystic ovary syndrome in the pediatric population

Polycystic ovary syndrome (PCOS) is a common disorder characterized by hyperandrogenism and disordered gonadotropin secretion, often associated with insulin resistance. The syndrome, which modulates both hormonal and metabolic processes, is the most common endocrinopathy in reproductive-age women and increases a woman's risk of infertility, endometrial pathology, and cardiometabolic disease. As it is currently defined, PCOS most likely encompasses several distinct diseases with similar clinical phenotypes but different underlying pathophysiological processes. However, hyperandrogenism remains the syndrome's clinical hallmark. The clinical manifestations of PCOS often emerge during childhood or in the peripubertal years, suggesting that the syndrome is influenced by fetal programming and/or early postnatal events. However, given that the full clinical spectrum of PCOS does not typically appear until puberty, a "two-hit" hypothesis has been proposed: (1) a girl develops hyperandrogenism via one or more of many different potential mechanisms; (2) the preexisting hyperandrogenism subsequently disturbs the hypothalamic–pituitary–ovarian axis, resulting in ovulatory dysfunction and sustained hyperandrogenism. No consensus guidelines exist regarding the diagnosis and management of PCOS in the pediatric population; however, because the syndrome is a diagnosis of exclusion, the clinical evaluation of girls suspected of having PCOS is aimed at excluding other causes of androgen excess and menstrual dysfunction. For the syndrome's management, emphasis is placed on lifestyle and symptom-directed treatment.

Pathology of congenital generalized lipodystrophy in Agpat2-/- mice

Congenital generalized lipodystrophy (CGL) comprises a heterogeneous group of rare diseases associated with partial or total loss of adipose tissue. Of these, autosomal recessive Berardinelli-Seip congenital lipodystrophy (BSCL) is characterized by the absence of metabolically active subcutaneous and visceral adipose tissues. Metabolic abnormalities associated with lipodystrophy include insulin resistance, hypertriglyceridemia, hepatic steatosis, and diabetes. One form of BSCL has been linked to genetic mutations affecting the lipid biosynthetic enzyme 1-acyl-sn-glycerol 3-phosphate O-acyltransferase 2 (AGPAT2), which is highly expressed in adipose tissue. Precisely how AGPAT2 deficiency causes lipodystrophy remains unresolved, but possible mechanisms include impaired lipogenesis (triglyceride synthesis and storage), blocked adipogenesis (differentiation of preadipocytes to adipocytes), or apoptosis/necrosis of adipocytes. Agpat2(-/-) mice share important pathophysiologic features of CGL previously reported in humans. However, the small white adipose tissue (WAT) depots consisting largely of amoeboid adipocytes with microvesiculated basophilic cytoplasm showed that adipogenesis with deficient lipogenesis was present in all usual locations. Although well-defined lobules of brown adipose tissue (BAT) were present, massive necrosis resulted in early ablation of BAT. Although necrotic or apoptotic adipocytes were not detected in WAT of 10-day-old Agpat2(-/-), the absence of adipocytes in aged mice indicates that these cells must undergo necrosis/apoptosis at some point. Another significant finding in aged lipodystrophic mice was massive pancreatic islet hypertrophy in the face of chronic hyperglycemia, which suggests that glucotoxicity is insufficient by itself to cause β-cell loss and that adipocyte-derived factors help regulate total β-cell mass.

The potential effects of ethyl acetate fraction from Curcuma longa L. on lipolysis in differentiated 3T3-L1 adipocytes

The effects of the turmeric ethyl acetate fraction (TEF) from the methanolic extract from Curcuma longa L. on lipid metabolism and underlying mechanisms of lipolysis were investigated in 3T3-L1 adipocytes. The intracellular lipid droplets were stained with Oil red O dye and quantified. Compared to the control, lipid accumulation was significantly decreased by 46.6% with treatment by TEF at the concentration of 20 microg/mL. The intracellular triglyceride (TG) level was also reduced by 37.9% at the concentration of 20 microg/mL. To determine the mechanism for TG content reduction, levels of glucose uptake and glycerol release were measured. Incubation of the 3T3-L1 adipocytes with TEF for 4 hours significantly lowered the cellular level of glucose in a dose-dependent manner. Furthermore, cellular expression of insulin-responsive glucose transporter (GLUT)-4 was decreased by 46%, indicating that reduced glucose uptake was due to a decrease in cellular GLUT-4 expression. In addition, the level of free glycerol released into the cultured medium was increased by 36.4% with the treatment by TEF. In subsequent measurements using quantitative real-time polymerase chain reaction, mRNA levels of hormone-sensitive lipase (HSL) and adipose TG lipase (ATGL) were elevated by 34.8% and 16.9%, respectively, at the concentration of 20 microg/mL. These results suggest that TEF partially inhibits lipogenesis by the suppression of glucose uptake via the decreased expression of cellular GLUT-4 and stimulates lipolysis through the induction of HSL and/or ATGL gene expression, resulting in the increased glycerol release.

Modulatory effect of grape-seed procyanidins on local and systemic inflammation in diet-induced obesity rats

Chronic low-grade inflammation in obesity is characterized by macrophage accumulation in white adipose tissue (WAT) and abnormal cytokine production. We tested the hypothesis that grape-seed procyanidin extract (PE), with known anti-inflammatory and antioxidant effects, would improve local and systemic inflammation in diet-induced obesity rats. First, we analyzed the preventive effects of procyanidins (30 mg/kg per day) on rats fed a 60% kcal fat diet for 19 weeks. Second, we induced cafeteria diet obesity for 13 weeks to investigate the corrective effects of two PE doses (25 and 50 mg/kg per day) for 10 and 30 days. In the preventive model, PE group had reduced not only body weight but also plasmatic systemic markers of inflammation tumor necrosis factor-α (TNF-α) and C-reactive protein (CRP). The PE preventive treatment significantly showed an increased adiponectin expression and decreased TNF-α, interleukin-6 and CRP expression in mesenteric WAT and muscle TNF-α. A reduced NF-κB activity in liver is also observed which can be related to low expression rates of hepatic inflammatory markers found in PE group. Finally, PE dietary supplementation is linked to a reduced expression of Emr1 (specific marker of macrophage F4/80), which suggests a reduced macrophage infiltration of WAT. In the corrective model, however, only the high dose of PE reduced CRP plasma levels in the short treatment without changes in plasmatic TNF-α. In conclusion, orally ingested PE helps preventing imbalanced obesity cytokine pattern, but its corrective effects need to be further investigated. The dietary regular intake of food or drinks containing procyanidins might help prevent low-grade inflammatory-related diseases.

De novo lipogenesis and stearoyl-CoA desaturase are coordinately regulated in the human adipocyte and protect against palmitate-induced cell injury

De novo lipogenesis (DNL) is paradoxically up-regulated by its end product, saturated fatty acids (SAFAs). We tested the hypothesis that SAFA-induced up-regulation of DNL reflects coordinate up-regulation of elongation and desaturation pathways for disposal of SAFAs and production of monounsaturated fatty acids to protect cells from SAFA toxicity. Human preadipocytes were differentiated in vitro for 14 days with [U-(13)C]palmitate (0-200 microM) to distinguish exogenous fatty acids from those synthesized by DNL. Exogenous palmitate up-regulated DNL (p < 0.001) concomitantly with SCD and elongation (each p < 0.001). Adipocytes from some donors were intolerant to high palmitate concentrations (400 microM). Palmitate-intolerant cells showed lower TG accumulation. They had lower expression of SCD mRNA and less monounsaturated fatty acids in TG, emphasizing the importance of desaturation for dealing with exogenous SAFAs. There was greater [U-(13)C]palmitate incorporation in phospholipids. SCD knockdown with small interfering RNA caused down-regulation of DNL and of expression of DNL-related genes, with reduced membrane fluidity (p < 0.02) and insulin sensitivity (p < 0.01), compared with scrambled small interfering RNA controls. There was preferential channeling of DNL-derived versus exogenous palmitate into elongation and of DNL-derived versus exogenous stearate into desaturation. DNL may not act primarily to increase fat stores but may serve as a key regulator, in tandem with elongation and desaturation, to maintain cell membrane fluidity and insulin sensitivity within the human adipocyte.

Adipose tissue expandability and the early origins of PCOS

The most prevalent phenotypes of polycystic ovary syndrome (PCOS) are characterized by insulin resistance and androgen excess. The adipose tissue (AT) expandability hypothesis explains the development of insulin resistance in obesity and in cases of AT deficit. In line with this hypothesis, we propose that hyperinsulinemic androgen excess in PCOS is often underpinned by exhaustion of the capacity to expand subcutaneous AT in a metabolically safe way. Such exhaustion might occur when a positive energy imbalance meets a normal fat-storage capacity and/or when a normal energy balance faces a low fat storage capacity. This concept thus explains how PCOS phenotypes might result from obesity, prenatal growth restraint or a genetic lipodystrophy, or, experimentally, from prenatal androgen excess.

Low-birth weight children develop lower sex hormone binding globulin and higher dehydroepiandrosterone sulfate levels and aggravate their visceral adiposity and hypoadiponectinemia between six and eight years of age

BACKGROUND

Most children born small for gestational age (SGA) normalize their body size by late infancy. Between 2 and 6 yr, such SGA children develop higher circulating levels of insulin, lower levels of adiponectin, and more visceral fat than appropriate-for-gestational-age (AGA) controls, even in the absence of overweight. Here we report on their further course between 6 and 8 yr. STUDY DESIGN AND POPULATION: Longitudinal study over 2 yr comparing data from 32 AGA vs. 32 SGA children, matched for gender, height, weight, and body mass index at the age of 6 yr.

MAIN OUTCOMES

Fasting insulin, dehydroepiandrosterone sulfate (DHEAS), SHBG, high-molecular-weight (HMW) adiponectin, leptin, IGF-I; body composition by absorptiometry; and abdominal fat partitioning by magnetic resonance imaging.

RESULTS

Between 6 and 8 yr, novel AGA-vs.-SGA divergences emerged (higher DHEAS and lower SHBG in SGA; P < 0.001), and some earlier divergences widened further (HMW adiponectin, visceral fat; P < 0.001), whereas others stabilized (fasting insulin, IGF-I). At age 8 yr, the most discerning features of SGA children were a high ratio of visceral over sc fat in the abdominal region (69% of SGA children), HMW hypoadiponectinemia (41%), fasting hyperinsulinemia (34%), and elevated circulating IGF-I levels (31%).

CONCLUSION

SGA children with spontaneous catch-up growth develop relatively high DHEAS and low SHBG levels and become more often HMW hypoadiponectinemic and viscerally adipose between 6 and 8 yr of age.

Obesity, abdominal obesity, and insulin resistance

The correlation of body mass index (BMI) with both adiposity and risk for type 2 diabetes mellitus (DM) is positive. An elevated BMI is also associated with increased mortality from cardiovascular disease (CVD). However, for any given BMI measurement, some persons are at risk for type 2 DM and CVD, while others are not. This disparity of risk may relate to differences in age, fitness, and body composition, including body fat. Obesity- excess body fat- is associated with insulin resistance. Abdominal obesity, in particular, places people at higher risk for developing insulin resistance and, consequently, is associated with an increased risk for type 2 DM and CVD. The association between obesity and insulin resistance is largely due to changes in the function of adipose tissue, specifically, increased release of free fatty acids and abnormalities in adipokine secretion. The properties of visceral adipose tissue may cause these dysfunctions to become magnified. Weight loss has the potential to improve insulin sensitivity through alterations in adipose tissue function.

Patterns of abdominal fat distribution: the Framingham Heart Study

OBJECTIVE

The prevalence of abdominal obesity exceeds that of general obesity. We sought to determine the prevalence of abdominal subcutaneous and visceral obesity and to characterize the different patterns of fat distribution in a community-based sample.

RESEARCH DESIGN AND METHODS

Participants from the Framingham Heart Study (n = 3,348, 48% women, mean age 52 years) underwent multidetector computed tomography; subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) volumes were assessed. Sex-specific high SAT and VAT definitions were based on 90th percentile cut points from a healthy referent sample. Metabolic risk factors were examined in subgroups with elevated SAT and VAT.

RESULTS

The prevalence of high SAT was 30% (women) and 31% (men) and that for high VAT was 44% (women) and 42% (men). Overall, 27.8% of the sample was discordant for high SAT and high VAT: 19.9% had SAT less than but VAT equal to or greater than the 90th percentile, and 7.9% had SAT greater than but VAT less than the 90th percentile. The prevalence of metabolic syndrome was higher among women and men with SAT less than the 90th percentile and high VAT than in those with high SAT but VAT less than the 90th percentile, despite lower BMI and waist circumference. Findings were similar for hypertension, elevated triglycerides, and low HDL cholesterol.

CONCLUSIONS

Nearly one-third of our sample has abdominal subcutaneous obesity, and >40% have visceral obesity. Clinical measures of BMI and waist circumference may misclassify individuals in terms of VAT and metabolic risk.

Visfatin in human pregnancy: maternal gestational diabetes vis-à-vis neonatal birthweight

OBJECTIVE

Adipose tissue dysfunction, characterized by dysregulation of adipokines production and/or secretion, has been implicated in the pathophysiology of type-2 diabetes mellitus, a metabolic complication closely related to gestational diabetes mellitus (GDM). Recently, an association between circulating maternal visfatin, a novel adipokine with metabolic and immunoregulatory properties, and impaired glucose metabolism as well as with altered fetal growth, has been proposed. The aims of this study were to determine whether there is an association between maternal plasma visfatin concentration, GDM, and a large-for-gestational-age (LGA) newborn.

STUDY DESIGN

This cross-sectional study, included pregnant women at term in the following groups: 1) normal pregnancy and an appropriate-for-gestational-age (AGA) neonate (n=54); 2) normal pregnancy and an LGA newborn (n=47); 3) GDM and an AGA newborn (n=56); 4) GDM and an LGA newborn (n=45). The study population was further stratified by first trimester BMI (<25 vs. > or =25 kg/m(2)). Maternal plasma visfatin concentration was determined by ELISA. Parametric and non-parametric statistics were used for analysis.

RESULTS

1) Among women who delivered an AGA neonate, the median maternal plasma concentration of visfatin was higher in patients with GDM than in those with a normal pregnancy; 2) Among women with a normal pregnancy, those who delivered an LGA neonate had a higher median maternal plasma visfatin concentration than those who delivered an AGA neonate; 3) among patients with normal BMI, there were no significant differences in the median maternal plasma visfatin concentration between the four study groups; and 4) maternal GDM, as well as delivery of an LGA neonate were independently associated with a higher maternal plasma visfatin concentrations.

CONCLUSION

The linkage between increased maternal circulating visfatin and the presence of GDM or delivery of an LGA neonate supports the hypothesis that perturbation of adipokines homeostasis may play a role in the pathophysiology of GDM or excess fetal growth.

Grape-seed procyanidins prevent low-grade inflammation by modulating cytokine expression in rats fed a high-fat diet

OBJECTIVE

The main objective of this study was to evaluate the effect of procyanidin intake on the level of inflammatory mediators in rats fed a hyperlipidic diet, which are a model of low-grade inflammation as they show an altered cytokine production.

DESIGN

Male Zucker Fa/fa rats were randomly grouped to receive a low-fat (LF) diet, a high-fat (HF) diet or a high-fat diet supplemented with procyanidins from grape seed (HFPE) (3.45 mg/kg feed) for 19 weeks and were then euthanized. We determined biochemical parameters, C-reactive protein (CRP) and IL-6 levels in plasma. Adipose tissue depots and body weight were also determined. We assessed CRP, IL-6, TNF-alpha and adiponectin gene expression in liver and white adipose tissue (WAT).

RESULTS

As expected, rats fed the HF diet show an enhanced production of CRP. Our results demonstrate that the HFPE diet decreases rat plasma CRP levels but not IL-6 levels. The decrease in plasma CRP in HFPE rats is related to a down-regulation of CRP mRNA expression in the liver and mesenteric WAT. We have also shown a decrease in the expression of the proinflammatory cytokines TNF-alpha and IL-6 in the mesenteric WAT. In contrast, adiponectin mRNA is increased in this tissue due to the procyanidin treatment. As previously reported, CRP plasma levels correlate positively with its expression in the mesenteric WAT, suggesting that procyanidin extract (PE) modulates CRP at the synthesis level. CRP plasma levels also correlate positively with body weight. As expected, body weight is associated with the adiposity index. Also, TNF-alpha expression and IL-6 expression have a strong positive correlation. In contrast, the expression of the anti-inflammatory cytokine adiponectin correlates negatively with the expression of TNF-alpha and IL-6 in the mesenteric WAT.

CONCLUSION

These results suggest a beneficial effect of PE on low-grade inflammatory diseases, which may be associated with the inhibition of the proinflammatory molecules CRP, IL-6 and TNF-alpha and the enhanced production of the anti-inflammatory cytokine adiponectin. These findings provide a strong impetus to explore the effects of dietary polyphenols in reducing obesity-related adipokine dysregulation to manage cardiovascular and metabolic risk factors.

Regulation of lipin-1 gene expression by glucocorticoids during adipogenesis

Lipin-1 deficiency in the mouse causes generalized lipodystrophy, characterized by impaired adipose tissue development and insulin resistance. Lipin-1 expression in differentiating preadipocytes is required for normal expression of adipogenic transcription factors, including peroxisome proliferator-activated receptor gamma and CCAAT enhancer binding protein alpha, and for the synthesis of triacylglycerol. The requirement of lipin-1 for adipocyte differentiation can be explained, in part, by its activity as the sole adipocyte phosphatidic acid phosphatase-1 enzyme, which converts phosphatidate to diacylglycerol, the immediate precursor of triacylglycerol. Here we identify glucocorticoids as the stimulus for the induction of lipin-1 expression in differentiating adipocytes, and characterize a glucocorticoid response element (GRE) in the Lpin1 promoter. The Lpin1 GRE binds to the glucocorticoid receptor and leads to transcriptional activation in adipocytes and hepatocytes, as demonstrated by reporter gene transcription, electrophoretic mobility shift, and chromatin immunoprecipitation assays. This represents the first gene regulatory element identified to directly influence lipin-1 expression levels, and may modulate lipin-1 mRNA levels in adipose tissue and liver in conditions associated with increased local glucocorticoid concentrations in vivo, such as obesity and fasting.