Adipose tissue as an endocrine organ

Impaired Gallbladder Motility and Increased Gallbladder Wall Thickness in Patients with Nonalcoholic Fatty Liver Disease

BACKGROUND/AIMS

Nonalcoholic fatty liver disease (NAFLD) is currently the most common chronic liver disease worldwide. Along with the increase in the incidence of NAFLD and associated obesity, an increase in gallbladder disease (GD) has been noted. This has led to the identification of a new disease entity called fatty GD. There is a gap in the literature on the dynamics of gallbladder function in patients with NAFLD.

METHODS

An observational case-control study, a total of 50 patients with biopsy proven NAFLD without gallbladder stone/sludge and 38 healthy comparison subjects were enrolled. Fasting, postprandial gallbladder volumes (PGV), gallbladder ejection fraction (GEF), and fasting gallbladder wall thickness (FGWT) were measured by real-time 2-dimensional ultrasonography.

RESULTS

Fasting gallbladder wall thickness, fasting gallbladder volumes and PGV were significantly higher in patients with NAFLD than control subjects (P < 0.001, P = 0.006, and P < 0.001, respectively). Gallbladder ejection fraction was significantly lower in the NAFLD group than the controls (P = 0.008). The presence of NAFLD was an independent predictor for GEF, PGV, and FGWT. Also, steatosis grade was an independent predictor for GEF, and GEF was significantly lower in the nonalcoholic steatohepatitis (NASH) subgroup than the controls.

CONCLUSIONS

Gallbladder dysfunction and increase in gallbladder wall thickness exists in asymptomatic (without stone/sludge and related symptoms) patients with NAFLD and are useful in identifying fatty GD. Measurement of these variables in NAFLD patients may be useful in identifying those at higher risk for GD.

Adipocyte nuclei captured from VAT and SAT

Background

Obesity-related comorbidities are thought to result from the reprogramming of the epigenome in numerous tissues and cell types, and in particular, mature adipocytes within visceral and subcutaneous adipose tissue, VAT and SAT. The cell-type specific chromatin remodeling of mature adipocytes within VAT and SAT is poorly understood, in part, because of the difficulties of isolating and manipulating large fragile mature adipocyte cells from adipose tissues.

Methods

We constructed MA-INTACT (Mature Adipocyte-Isolation of Nuclei TAgged in specific Cell Types) mice using the adiponectin (ADIPOQ) promoter (ADNp) to tag the surface of mature adipocyte nuclei with a reporter protein. The SUN1mRFP1Flag reporter is comprised of a fragment of the nuclear transmembrane protein SUN1, the fluorescent protein mRFP1, and three copies of the Flag epitope tag.

Results

Mature adipocyte nuclei were rapidly and efficiently immuno-captured from VAT and SAT (MVA and MSA nuclei, respectively), of MA-INTACT mice. MVA and MSA nuclei contained 1,000 to 10,000-fold higher levels of adipocyte-specific transcripts, ADIPOQ, PPARg2, EDNRB, and LEP, relative to uncaptured nuclei, while the latter expressed higher levels of leukocyte and endothelial cell markers IKZF1, RETN, SERPINF1, SERPINE1, ILF3, and TNFA. MVA and MSA nuclei differentially expressed several factors linked to adipogenesis or obesity-related health risks including CEBPA, KLF2, RETN, SERPINE1, and TNFA. The various nuclear populations dramatically differentially expressed transcripts encoding chromatin remodeler proteins regulating DNA cytosine methylation and hydroxymethylation (TETs, DNMTs, TDG, GADD45s) and nucleosomal histone modification (ARID1A, KAT2B, KDM4A, PRMT1, PRMT5, PAXIP1). Remarkably, MSA and MVA nuclei expressed 200 to 1000-fold higher levels of thermogenic marker transcripts PRDM16 and UCP1.

Conclusions

The MA-INTACT mouse enables a simple way to perform cell-type specific analysis of highly purified mature adipocyte nuclei from VAT and SAT and increases the statistical significance of data collected on adipocytes. Isolated VAT and SAT adipocyte nuclei expressed distinct patterns of transcripts encoding chromatin remodeling factors and proteins relevant to diabetes, cardiovascular disease, and thermogenesis. The MA-INTACT mouse is an useful model to test the impact of caloric intake, dietary nutrients, exercise, and pharmaceuticals on the epigenome-induced health risks of obesity.

Electronic supplementary material

The online version of this article (doi:10.1186/s40608-016-0112-6) contains supplementary material, which is available to authorized users.

The Effect of Resveratrol and Quercetin Treatment on PPAR Mediated Uncoupling Protein (UCP-) 1, 2, and 3 Expression in Visceral White Adipose Tissue from Metabolic Syndrome Rats

Uncoupling proteins (UCPs) are members of the mitochondrial anion carrier superfamily involved in the control of body temperature and energy balance regulation. They are currently proposed as therapeutic targets for treating obesity and metabolic syndrome (MetS). We studied the gene expression regulation of UCP1, -2, and -3 in abdominal white adipose tissue (WAT) from control and MetS rats treated with two doses of a commercial mixture of resveratrol (RSV) and quercetin (QRC). We found that UCP2 was the predominantly expressed isoform, UCP3 was present at very low levels, and UCP1 was undetectable. The treatment with RSV + QRC did not modify UCP3 levels; however, it significantly increased UCP2 mRNA in control and MetS rats in association with an increase in oleic and linoleic fatty acids. WAT from MetS rats showed a significantly increased expression of peroxisome proliferator-activated receptor (PPAR)-α and PPAR-γ when compared to the control group. Furthermore, PPAR-α protein levels were increased by the highest dose of RSV + QRC in the control and MetS groups. PPAR-γ expression was only increased in the control group. We conclude that the RSV + QRC treatment leads to overexpression of UCP2, which is associated with an increase in MUFA and PUFA, which might increase PPAR-α expression.

Association between exposures to brominated trihalomethanes, hepatic injury and type II diabetes mellitus

Non-alcoholic fatty liver disease (NAFLD) is considered the most common liver disorder in the Western world, commonly diagnosed in the majority of obese patients with type 2 diabetes mellitus (T2DM). Metabolic disrupting chemicals with short half-lives, such as those of halogenated structure (trihalomethanes, THM) have been linked with hepatic insulin resistance phenomena in animal studies. However, human studies evaluating the role of THM exposure on liver pathogenesis and T2DM disease process are scarce. The objectives of this study were to: i) determine the association of urinary brominated THM (BrTHM) levels and T2DM disease status, and ii) investigate the association between urinary BrTHM levels and serum alanine aminotransferase (ALT) concentrations, often used as surrogate markers of NAFLD. A pilot case-control study was conducted in Nicosia, Cyprus (n=95). Cases were physician-diagnosed T2DM patients and controls were healthy individuals. Liver enzymes, leptin and TNF-α were measured in sera, while urinary THM levels were measured using tandem mass spectrometry. Diabetics had higher levels of serum leptin, body mass index and ALT than the controls. Among all study participants those with serum ALT levels above the median (17IU/L) had higher mean tribromomethane (TBM) concentrations compared to those with serum ALT below 17IU/L. A significant increase in the odds of having above the median serum ALT levels [OR 6.38, 95% CI: 1.11, 42.84 (p=0.044)] was observed for each unit increase in creatinine-unadjusted urinary TBM levels, along with BMI and past smoking, after adjusting for possible confounders, such as urinary creatinine, age, sex, and leptin; no other THM compound showed a significant association with serum ALT. Logistic regression models for T2DM using the urinary BrTHM as exposure variables did not reach the predetermined level of significance. The interplay between exposures to BrTHM and the initiation of key pathophysiological events relating to hepatic injury (ALT) and inflammation (leptin) was recognized via the use of selected biomarkers of effect. Our evidence that THM could act as hepatic toxins with a further initiation of diabetogenic effects call for additional studies to help us better understand the disease process of the two co-morbidities (NAFLD and T2DM).

C-reactive protein inhibits high-molecular-weight adiponectin expression in 3T3-L1 adipocytes via PI3K/Akt pathway

Adiponectin, an adipose-specific protein hormone, is secreted from white adipose tissue and involved in glucose and lipid metabolism. It is assembled into low-molecular-weight trimer (LMW), middle-molecular-weight hexameric (MMW) and high-molecular-weight (HMW), among which HMW exhibits higher activity. In this study, we proved that C-reactive protein (CRP), an inflammatory marker, inhibited adiponectin expression, especially HMW in time-and dose-dependent manners. Furthermore, CRP decreased the HMW/total adiponectin ration and reduced adiponectin assembly by increasing ERp44, and decreasing Ero1-α and DsbA-L. CRP activated pAkt, the downstream of PI3K. Inhibition of PI3K or pAkt abolished the effect of CRP. Our study suggested that CRP decreased adiponectin expression and multimerization, while CRP-induced decline in adiponectin might be mediated through the PI3K/Akt pathway.

Cardiometabolic risk markers of normal weight and excess body weight in Brazilian adolescents

Excess body weight leads to a variety of metabolic changes and increases the risk for cardiovascular diseases (CVD) in adulthood. The objective of this study was to investigate the presence of risk markers for CVD among Brazilian adolescents of normal weight and with excess body weight. The markers included blood pressure, C-reactive protein, homocysteine, tumor necrosis factor alpha, fibrinogen, fasting insulin and glucose, homeostasis model assessment of insulin resistance (HOMA-IR), leptin, total cholesterol, low-density lipoprotein cholesterol (LDL-c), high-density lipoprotein cholesterol (HDL-c), and triglycerides. We calculated odds ratios (OR) using logistic regression and adjusted for potential confounders such as age, sex, physical activity, and socioeconomic background. Compared with normal weight subjects, overweight/obese adolescents were more likely to have higher systolic blood pressure (OR = 3.49, p < 0.001), fasting insulin (OR = 8.03, p < 0.001), HOMA-IR (OR = 8.03, p < 0.001), leptin (OR = 5.55, p < 0.001), and LDL-c (OR = 5.50, p < 0.001) and lower serum HDL-c concentrations (OR = 2.76, p = 0.004). After adjustment for confounders, the estimates did not change substantially, except for leptin for which the risk associated with overweight increased to 11.09 (95% CI: 4.05-30.35). In conclusion, excess body weight in adolescents exhibits strong associations with several markers that are established as causes of CVD in adults. This observation stresses the importance of primary prevention and of maintaining a healthy body weight throughout adolescence to reduce the global burden of CVD.

Adipose tissue attenuation as a marker of adipose tissue quality: Associations with six-year changes in body weight

OBJECTIVE

Weight gain is associated with fat volume increases, but associations with fat quality are less well characterized The associations of weight change with visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) volume and attenuation were investigated.

METHODS

Computed tomography abdominal scans were acquired on a Framingham Heart Study subset (N = 836; 40.2% women; mean age 45.7 years), a mean of 6.1 years apart. Fat attenuation estimated fat quality.

RESULTS

Mean weight change was +2.0 (SD 6.8; IQR -0.7, 5.0) kg in women and +2.7 (SD 6.0; IQR -0.5, 5.4) kg in men. Per 2.5 kg weight increase in women, VAT volume increased 126 cm(3) (95% CI, 112-140, p < 0.0001), SAT volume increased 258 cm(3) (95% CI, 239-278, p < 0.0001), and fat attenuation decreased (i.e., fat quality worsened) in VAT and SAT (p < 0.0001). Increasing VAT volume was associated with decreasing fat attenuation even after accounting for weight change. Relative to weight-stable women (n = 129), women who lost >2.5 kg (n = 58) had smaller SAT attenuation decreases (p < 0.0001). Similar patterns were seen in men.

CONCLUSIONS

Weight gain was associated with decreases in fat attenuation independent of VAT and SAT volume changes. These findings highlighted the associations of weight gain and worsening fat attenuation, suggesting fat attenuation may be dynamic.

Central Administration of Galanin Receptor 1 Agonist Boosted Insulin Sensitivity in Adipose Cells of Diabetic Rats

Our previous studies testified the beneficial effect of central galanin on insulin sensitivity of type 2 diabetic rats. The aim of the study was further to investigate whether central M617, a galanin receptor 1 agonist, can benefit insulin sensitivity. The effects of intracerebroventricular administration of M617 on insulin sensitivity and insulin signaling were evaluated in adipose tissues of type 2 diabetic rats. The results showed that central injection of M617 significantly increased plasma adiponectin contents, glucose infusion rates in hyperinsulinemic-euglycemic clamp tests, GLUT4 mRNA expression levels, GLUT4 contents in plasma membranes, and total cell membranes of the adipose cells but reduced the plasma C-reactive protein concentration in nondiabetic and diabetic rats. The ratios of GLUT4 contents were higher in plasma membranes to total cell membranes in both nondiabetic and diabetic M617 groups than each control. In addition, the central administration of M617 enhanced the ratios of pAkt/Akt and pAS160/AS160, but not phosphorylative cAMP response element-binding protein (pCREB)/CREB in the adipose cells of nondiabetic and diabetic rats. These results suggest that excitation of central galanin receptor 1 facilitates insulin sensitivity via activation of the Akt/AS160 signaling pathway in the fat cells of type 2 diabetic rats.

GPER/GPR30 Knockout Mice: Effects of GPER on Metabolism

Endogenous estrogens, predominantly 17β-estradiol (E2), mediate various diverse effects throughout the body in both normal physiology and disease. Actions include development (including puberty) and reproduction as well as additional effects throughout life in the metabolic, endocrine, musculoskeletal, nervous, cardiovascular, and immune systems. The actions of E2 have traditionally been attributed to the classical nuclear estrogen receptors (ERα and ERβ) that largely mediate transcriptional/genomic activities. However, more recently the G protein-coupled estrogen receptor GPER/GPR30 has become recognized as an essential mediator of certain, and particularly rapid, signaling events in response to E2. Murine genetic knockout (KO) models represent an important approach to understand the mechanisms of E2 action in physiology and disease. Studies of GPER KO mice over the last years have revealed functions for GPER in the regulation of obesity, insulin resistance and glucose intolerance, among other areas of (patho)physiology. This chapter focuses on methods for the evaluation of metabolic parameters in vivo and ex vivo with an emphasis on glucose homeostasis and metabolism through the use of glucose and insulin tolerance tests, pancreatic islet and adipocyte isolation and characterization.

Body condition score and plane of nutrition prepartum affect adipose tissue transcriptome regulators of metabolism and inflammation in grazing dairy cows during the transition period

Recent studies demonstrating a higher incidence of metabolic disorders after calving have challenged the management practice of increasing dietary energy density during the last ~3 wk prepartum. Despite our knowledge at the whole-animal level, the tissue-level mechanisms that are altered in response to feeding management prepartum remain unclear. Our hypothesis was that prepartum body condition score (BCS), in combination with feeding management, plays a central role in the peripartum changes associated with energy balance and inflammatory state. Twenty-eight mid-lactation grazing dairy cows of mixed age and breed were randomly allocated to 1 of 4 treatment groups in a 2 × 2 factorial arrangement: 2 prepartum BCS categories (4.0 and 5.0, based on a 10-point scale; BCS4, BCS5) obtained via differential feeding management during late-lactation, and 2 levels of energy intake during the 3 wk preceding calving (75 and 125% of estimated requirements). Subcutaneous adipose tissue was harvested via biopsy at -1, 1, and 4 wk relative to parturition. Quantitative polymerase chain reaction was used to measure mRNA and microRNA (miRNA) expression of targets related to fatty acid metabolism (lipogenesis, lipolysis), adipokine synthesis, and inflammation. Both prepartum BCS and feeding management had a significant effect on mRNA and miRNA expression throughout the peripartum period. Overfed BCS5 cows had the greatest prepartum expression of fatty acid synthase (FASN) and an overall greater expression of leptin (LEP); BCS5 was also associated with greater overall adiponectin (ADIPOQ) and peroxisome proliferator-activated receptor gamma (PPARG), whereas overfeeding upregulated expression of proadipogenic miRNA. Higher postpartum expression of chemokine ligand 5 (CCL5) and the cytokines interleukin 6 (IL6) and tumor necrosis factor (TNF) was detected in overfed BCS5 cows. Feed-restricted BCS4 cows had the highest overall interleukin 1 (IL1B) expression. Prepartum feed restriction resulted in greater chemokine ligand 2 (CCL2) expression. Overall, changes in mRNA expression were consistent with the expression pattern of inflammation-related miRNA. These data shed light on molecular mechanisms underlying the effect of prepartum BCS and feeding management on metabolic and inflammatory status of adipose tissue during the peripartum period. Data support the use of a controlled feed restriction prepartum in optimally conditioned cows, as well as the use of a higher level of dietary energy in under-conditioned cows.

Adiponectin Levels Differentiate Metabolically Healthy vs Unhealthy Among Obese and Nonobese White Individuals

CONTEXT

Adiponectin levels (ADPN) are lower in individuals with central obesity and cardiometabolic diseases. Conversely, studies have shown paradoxical hyperadiponectinemia (HA) in metabolically healthy obese (MHO) individuals of non-European descent. Moreover, individuals with higher sc to visceral adipose tissue (ie, higher peripheral adiposity) distribution have higher ADPNs. However, it is not known whether metabolically healthy individuals have predominantly peripheral adiposity along with higher ADPNs.

OBJECTIVE

This study aimed to evaluate the association of ADPN and adiposity distribution with metabolic health in white individuals.

DESIGN AND SETTING

This was a cross-sectional study of members of "Take Off Pounds Sensibly" weight loss club and their relatives.

PARTICIPANTS

We recruited 2486 (72% women, 61% obese) individuals. They were defined as metabolically healthy by absence of hypertension, diabetes, and dyslipidemia; and they were further classified into metabolically healthy nonobese (MHNO), metabolically unhealthy nonobese (MUNO), metabolically healthy obese (MHO), and metabolically unhealthy obese (MUO). Waist-to-hip ratios (WHRs) were used as markers of adiposity distribution. Insulin resistance was measured using homeostasis model assessment.

RESULTS

Among the four groups, MHNO had the lowest WHRs (higher peripheral adiposity) and highest ADPN, and MUO had highest WHRs (higher central adiposity) and lowest ADPN (P < .001). Among both nonobese and obese, metabolically healthy individuals had higher ADPN than metabolically unhealthy individuals (P < .05) after adjustment for age, sex, and body mass index. MHNO also had lower WHRs compared with MUNO (P < .01). Although WHRs were lower among MHO compared with MUO, the difference was not significant. In addition, nonobese and obese individuals with HA (defined using sex-specific cutoffs) had lower homeostasis model assessment and dyslipidemia compared with individuals without HA.

CONCLUSIONS

Higher ADPN and lower WHRs (higher peripheral adiposity) are associated with better metabolic health in both nonobese and obese white individuals. These results suggest that ADPN and peripheral adiposity play a key role in determining the metabolic health independent of body mass index.

Serum Omentin Levels in Adolescent Girls With Anorexia Nervosa and Obesity

It is believed that omentin is secreted by stromal cells of adipose tissue and modulates insulin sensitivity. Data from a few studies have shown lower serum omentin in obese children and higher in anorexia nervosa. However, to date, there is lack of research on serum omentin concentrations in adolescent patients in a wide range of body mass index (BMI) and insulin resistance. In this cross-sectional study omentin-1 serum concentrations were evaluated using commercially available ELISA kit in 47 Polish girls with restrictive anorexia nervosa (AN), 50 with simple obesity (OB) and 39 healthy controls (C). The mean serum omentin-1 concentration in girls with AN was statistically significantly higher than that of C and OB girls. Statistically significant (P<0.0001) negative correlations between the serum concentrations of omentin-1 and body weight (r=−0.73), BMI (r=−0.75), standard deviation score for body mass index (BMI-SDS) (r=−0.75), insulin (r=−0.81) and HOMA-IR index (r=−0.82) were seen in the entire examined population. We conclude, that omentin-1 is the nutritional marker reflecting body weight and insulin resistance. Our findings support the hypothesized role of omentin in maintenance of body weight and regulation of appetite and suggest the adaptation of its secretion to body weight and glucose metabolism.

Metabolic Syndrome and Menopause: Pathophysiology, Clinical and Diagnostic Significance

Menopause is a risk factor for cardiometabolic diseases, including metabolic syndrome (MetS), type 2 diabetes, and cardiovascular diseases. MetS is a constellation of interdependent factors such as insulin resistance, abdominal obesity, dyslipidemia, and hypertension. The prevalence of MetS in postmenopause is due to loss of the protective role of estrogens and increased circulating androgens resulting in changes to body fat distribution and development of abdominal obesity. Excessive visceral adipose tissue plays an important role due to synthesis and secretion of bioactive substances such as adipocytokines, proinflammatory cytokines, reactive oxygen species, prothrombotic, and vasoconstrictor factors. MetS may also impact risk assessment of breast cancer, osteoporosis and chronic kidney disease, and quality of life during the menopausal transition. Increased MetS has stimulated the exploration of new laboratory tests for early detection and therapies.

Adipose tissue hypoxia and low-grade inflammation: a possible mechanism for ethanol-related glucose intolerance?

The exact mechanism of ethanol's effects on glucose tolerance has not been well determined. The present study focuses for the first time on hypoxia and low-grade inflammation in adipose tissue (AT). In the in vivo experiments, twenty-four male Wistar rats were randomly allocated into control and ethanol feeding groups. Ethanol-treated rats received edible ethanol once a day at a total dosage of 5 g/kg per d, and the controls received distilled water. Ethanol volumes were adjusted every week. At the end of 8 weeks, we carried out an oral glucose tolerance test. Blood and AT were collected for measuring hypoxia-inducible factor-1α (HIF-1α), GLUT1, TNF-α, IL-6, leptin and vascular endothelial growth factor (VEGF). In the in vitro experiments, differentiated OP9 adipocytes were incubated with 100 mm of ethanol for 48 h; the media and cells were then collected for measuring HIF-1α, GLUT1, TNF-α and IL-6. The results showed that long-term ethanol consumption impaired glucose tolerance in rats. Ethanol consumption had little influence on body weight, but both epididymal and perirenal AT were markedly enlarged in the ethanol-treated rats as compared to the controls. Visceral adipose tissue (VAT) had accumulated, and the protein levels of HIF-1α and GLUT1, the indicators of hypoxia in rat epididymal AT and OP9 adipocytes, were elevated. Secondary to the AT hypoxia, the levels of inflammation-related adipokines, such as TNF-α, IL-6, leptin and VEGF, were increased. Based on these findings, we conclude that VAT hypoxia and low-grade inflammation might be a new mechanism in the treatment of ethanol-related diabetes.

Effect of 5-caffeoylquinic acid on the NF-κB signaling pathway, peroxisome proliferator-activated receptor gamma 2, and macrophage infiltration in high-fat diet-fed Sprague-Dawley rat adipose tissue

Obesity, considered as a consequence of overnutrition, sustains a low-degree inflammatory state and results in insulin-resistance and type 2 diabetes. Here, we investigated the anti-inflammatory effects of 5-caffeoylquinic acid (5-CQA) in high-fat diet-induced obese rats. Serum interleukin (IL)-6, monocyte chemotactic protein 1 (MCP-1), tumor necrosis factor-alpha (TNF-α), total cholesterol (TC), triglyceride (TG), and free fatty acid (FFA) levels were determined. Expression of genes related to TG metabolism, macrophage biomarkers, and inflammation was assessed by real-time PCR. Protein expression of NF-κB, PPARγ2, and phosphorylated IκBα was evaluated by western blotting, and the histology of adipose tissue was examined. Supplementation of the rat diet with 5-CQA reduced obesity development, macrophage infiltration, and steatosis. Additionally, 5-CQA decreased the expression of NF-κB and downstream inflammatory cytokines, but increased the expression of PPARγ2, in a dose-dependent manner. Thus, 5-CQA improved obesity and obesity-related metabolic disturbances via PPARγ2 and the NF-κB signaling pathway.

Ultra-structural morphology of long-term cultivated white adipose tissue-derived stem cells

White adipose tissue was long perceived as a passive lipid storage depot but it is now considered as an active and important endocrine organ. It also harbours not only adipocytes and vascular cells but also a wide array of immunologically active cells, including macrophages and lymphocytes, which may induce obesity-related inflammation. Recently, adipose tissue has been reported as a source of adult mesenchymal stem cells with wide use in regenerative medicine and tissue engineering. Their relatively non-complicated procurement and collection (often performed as liposuction during aesthetic surgery) and grand plasticity support this idea even more. We focused our research on exploring the issues of isolation and long-term cultivation of mesenchymal stem cells obtained from adipose tissue. Ultra-structural morphology of the cells cultivated in vitro has been studied and analysed in several cultivation time periods and following serial passages--up to 30 passages. In the first passages they had ultra-structural characteristics of cells with high proteosynthetic activity. Within the cytoplasm, big number of small lipid droplets and between them, sparsely placed, small and inconspicuous, electron-dense, lamellar bodies, which resembled myelin figures were observed. The cells from the later passages contained high number of lamellar electron-dense structures, which filled out almost the entire cytoplasm. In between, mitochondria were often found. These bodies were sometimes small and resembled myelin figures, but several of them reached huge dimensions (more than 1 µm) and their lamellar structure was not distinguishable. We did not have an answer to the question about their function, but they probably represented the evidence of active metabolism of lipids present in the cytoplasm of these cells or represented residual bodies, which arise after the breakdown of cellular organelles, notably mitochondria during long-term cultivation.

Normal-weight obesity: implications for cardiovascular health

We sought to review the epidemiological features and clinical implications of normal-weight obesity. The concept of normal-weight obesity has been recently reported as an important risk factor for cardiovascular disease, metabolic dysregulation, and poor functional outcomes. However, in clinical practice, normal-weight obesity is not commonly recognized. In this review, we examine the clinical significance and important epidemiological outcomes of normal-weight obesity and describe other variants of adiposity and adiposity-related metabolic status. The incorporation of measures of body fat content and distribution in the clinical setting could allow more accurate identification of adiposity-related long-term risk. This could in turn lead to early lifestyle changes and behavioral modifications that are essential to the treatment of obesity.

In vivo dedifferentiation of adult adipose cells

Introduction

Adipocytes can dedifferentiate into fibroblast-like cells in vitro and thereby acquire proliferation and multipotent capacities to participate in the repair of various organs and tissues. Whether dedifferentiation occurs under physiological or pathological conditions in vivo is unknown.

Methods

A tissue expander was placed under the inguinal fat pads of rats and gradually expanded by injection of water. Samples were collected at various time points, and morphological, histological, cytological, ultrastructural, and gene expression analyses were conducted. In a separate experiment, purified green fluorescent protein+ adipocytes were transplanted into C57 mice and collected at various time points. The transplanted adipocytes were assessed by bioluminescence imaging and whole-mount staining.

Results

The expanded fat pad was obviously thinner than the untreated fat pad on the opposite side. It was also tougher in texture and with more blood vessels attached. Hematoxylin and eosin staining and transmission electron microscopy indicated there were fewer monolocular adipocytes in the expanded fat pad and the morphology of these cells was altered, most notably their lipid content was discarded. Immunohistochemistry showed that the expanded fat pad contained an increased number of proliferative cells, which may have been derived from adipocytes. Following removal of the tissue expander, many small adipocytes were observed. Bioluminescence imaging suggested that some adipocytes survived when transplanted into an ischemic-hypoxic environment. Whole-mount staining revealed that surviving adipocytes underwent a process similar to adipocyte dedifferentiation in vitro. Monolocular adipocytes became multilocular adipocytes and then fibroblast-like cells.

Conclusions

Mature adipocytes may be able to dedifferentiate in vivo, and this may be an adipose tissue self-repair mechanism. The capacity of adipocytes to dedifferentiate into stem cell-like cells may also have a more general role in the regeneration of many tissues, notably in fat grafting.

Adipose-derived stems cells and their role in human cancer development, growth, progression, and metastasis: a systematic review

Obesity is a well recognized risk factor for several types of cancers, many of which occur solely or disproportionately in women. Adipose tissue is a rich source of adipose-derived stem cells (ASC), which have received attention for their role in cancer behavior. The purpose of this systematic review is to present the existing literature on the role of ASCs in the growth, development, progression, and metastasis of cancer, with an emphasis on malignancies that primarily affect women. To accomplish this goal, the bibliographic database PubMed was systematically searched for articles published between 2001 and 2014 that address ASCs' relationship to human cancer. Thirty-seven articles on ASCs' role in human cancer were reviewed. Literature suggests that ASCs exhibit cancer-promoting properties, influence/are influenced by the tumor microenvironment, promote angiogenesis, and may be associated with pathogenic processes through a variety of mechanisms, such as playing a role in hypoxic tumor microenvironment. ASCs appear to be important contributors to tumor behavior, but research in areas specific to women's cancers, specifically endometrial cancer, is scarce. Also, because obesity continues to be a major health concern, it is important to continue research in this area to improve understanding of the impact adiposity has on cancer incidence.

Exercise increases pancreatic β-cell viability in a model of type 1 diabetes through IL-6 signaling

Type 1 diabetes (T1D) is provoked by an autoimmune assault against pancreatic β cells. Exercise training enhances β-cell mass in T1D. Here, we investigated how exercise signals β cells in T1D condition. For this, we used several approaches. Wild-type and IL-6 knockout (KO) C57BL/6 mice were exercised. Afterward, islets from control and trained mice were exposed to inflammatory cytokines (IL-1β plus IFN-γ). Islets from control mice and β-cell lines (INS-1E and MIN6) were incubated with serum from control or trained mice or medium obtained from 5-aminoimidazole-4 carboxamide1-β-d-ribofuranoside (AICAR)-treated C2C12 skeletal muscle cells. Subsequently, islets and β cells were exposed to IL-1β plus IFN-γ. Proteins were assessed by immunoblotting, apoptosis was determined by DNA-binding dye propidium iodide fluorescence, and NO(•) was estimated by nitrite. Exercise reduced 25, 75, and 50% of the IL-1β plus IFN-γ-induced iNOS, nitrite, and cleaved caspase-3 content, respectively, in pancreatic islets. Serum from trained mice and medium from AICAR-treated C2C12 cells reduced β-cell death, induced by IL-1β plus IFN-γ treatment, in 15 and 38%, respectively. This effect was lost in samples treated with IL-6 inhibitor or with serum from exercised IL-6 KO mice. In conclusion, muscle contraction signals β-cell survival in T1D through IL-6.

Obesity, inflammation, and insulin resistance

White adipose tissue (WAT) is considered an endocrine organ. When present in excess, WAT can influence metabolism via biologically active molecules. Following unregulated production of such molecules, adipose tissue dysfunction results, contributing to complications associated with obesity. Previous studies have implicated pro- and anti-inflammatory substances in the regulation of inflammatory response and in the development of insulin resistance. In obese individuals, pro-inflammatory molecules produced by adipose tissue contribute to the development of insulin resistance and increased risk of cardiovascular disease. On the other hand, the molecules with anti-inflammatory action, that have been associated with the improvement of insulin sensitivity, have your decreased production. Imbalance of these substances contributes significantly to metabolic disorders found in obese individuals. The current review aims to provide updated information regarding the activity of biomolecules produced by WAT.

The effect of obesity and tobacco smoke exposure on inflammatory mediators and matrix metalloproteinases in rat model

Obesity is characterized by hypertrophy of adipose tissue and chronic obstructive pulmonary disease (COPD) by lung damage; both diseases are associated with systemic low-grade inflammation. There are no animal models combining obesity and COPD; therefore, these diseases were induced simultaneously in rats to analyze their effects on the expression of inflammatory mediators and enzymes involved in lung tissue remodeling. Obesity was induced with sucrose (30%) for 4 months concomitant with tobacco smoke exposure (20 cigarettes/day, 5 days/wk) for the last 2 months. Were evaluated: body weight, abdominal fat, dyslipidemia, glucose tolerance test (GTT), histology, inflammatory mediators with qPCR and enzyme-linked immunosorbent assay, matrix metalloproteinases (MMP-2), MMP-9, MMP-12, TIMP-1 and TIMP-2 through qRT-PCR, and MMP-2 and MMP-9 by gelatin zymography. The rats on a sucrose diet exhibited increased body weight, abdominal fat, triglycerides, GTT, and plasma levels of insulin, adiponectin, leptin, resistin, IL-6, IL-1β, tumor necrosis factor-α (TNF-α) and IFN-γ, upregulated lung IL-6, IL-1β, TNF-α and IFN-γ, showing hyperplastic bronchial and alveolar epithelium. The animals exposed to sucrose and tobacco smoke exhibited decreased body weight, abdominal fat and plasma levels of leptin, resistin, IL-1β and IFN-γ, reducing inflammation but showing emphysematous lesions. Expression of gelatinases and MMP-12 augmented in the rats exposed to tobacco smoke alone or combined with sucrose. Zymography showed prominent gelatinases activity in all the experimental groups. These results suggest that simultaneous exposure to sucrose and tobacco smoke decreases inflammation but results in emphysematous lesions similar to those observed with tobacco smoke exposure, suggesting that obesity does not confer any protective effect against lung damage.

Hypercholesterolemia induces adipose dysfunction in conditions of obesity and nonobesity

It is well known that hypercholesterolemia can lead to atherosclerosis and coronary heart disease. Adipose tissue represents an active endocrine and metabolic site, which might be involved in the development of chronic disease. Because adipose tissue is a key site for cholesterol metabolism and the presence of hypercholesterolemia has been shown to induce adipocyte cholesterol overload, it is critical to investigate the role of hypercholesterolemia on normal adipose function. Studies in preadipocytes revealed that cholesterol accumulation can impair adipocyte differentiation and maturation by affecting multiple transcription factors. Hypercholesterolemia has been observed to cause adipocyte hypertrophy, adipose tissue inflammation, and disruption of endocrine function in animal studies. Moreover, these effects can also be observed in obesity-independent conditions as confirmed by clinical trials. In humans, hypercholesterolemia disrupts adipose hormone secretion of visfatin, leptin, and adiponectin, adipokines that play a central role in numerous metabolic pathways and regulate basic physiologic responses such as appetite and satiety. Remarkably, treatment with cholesterol-lowering drugs has been shown to restore adipose tissue endocrine function. In this review the role of hypercholesterolemia on adipose tissue differentiation and maturation, as well as on hormone secretion and physiologic outcomes, in obesity and non–obesity conditions is presented.

Benefits of healthy adipose tissue in the treatment of diabetes

The major malfunction in diabetes mellitus is severe perturbation of glucose homeostasis caused by deficiency of insulin. Insulin deficiency is either absolute due to destruction or failure of pancreatic β cells, or relative due to decreased sensitivity of peripheral tissues to insulin. The primary lesion being related to insulin, treatments for diabetes focus on insulin replacement and/or increasing sensitivity to insulin. These therapies have their own limitations and complications, some of which can be life-threatening. For example, exogenous insulin administration can lead to fatal hypoglycemic episodes; islet/pancreas transplantation requires life-long immunosuppressive therapy; and anti-diabetic drugs have dangerous side effects including edema, heart failure and lactic acidosis. Thus the need remains for better safer long term treatments for diabetes. The ultimate goal in treating diabetes is to re-establish glucose homeostasis, preferably through endogenously generated hormones. Recent studies increasingly show that extra-pancreatic hormones, particularly those arising from adipose tissue, can compensate for insulin, or entirely replace the function of insulin under appropriate circumstances. Adipose tissue is a versatile endocrine organ that secretes a variety of hormones with far-reaching effects on overall metabolism. While unhealthy adipose tissue can exacerbate diabetes through limiting circulation and secreting of pro-inflammatory cytokines, healthy uninflamed adipose tissue secretes beneficial adipokines with hypoglycemic and anti-inflammatory properties, which can complement and/or compensate for the function of insulin. Administration of specific adipokines is known to alleviate both type 1 and 2 diabetes, and leptin mono-therapy is reported to reverse type 1 diabetes independent of insulin. Although specific adipokines may correct diabetes, administration of individual adipokines still carries risks similar to those of insulin monotherapy. Thus a better approach is to achieve glucose homeostasis with endogenously-generated adipokines through transplantation or regeneration of healthy adipose tissue. Our recent studies on mouse models show that type 1 diabetes can be reversed without insulin through subcutaneous transplantation of embryonic brown adipose tissue, which leads to replenishment of recipients’ white adipose tissue; increase of a number of beneficial adipokines; and fast and long-lasting euglycemia. Insulin-independent glucose homeostasis is established through a combination of endogenously generated hormones arising from the transplant and/or newly-replenished white adipose tissue. Transplantation of healthy white adipose tissue is reported to alleviate type 2 diabetes in rodent models on several occasions, and increasing the content of endogenous brown adipose tissue is known to combat obesity and type 2 diabetes in both humans and animal models. While the underlying mechanisms are not fully documented, the beneficial effects of healthy adipose tissue in improving metabolism are increasingly reported, and are worthy of attention as a powerful tool in combating metabolic disease.

Nonalcoholic fatty liver disease increases risk for gastroesophageal reflux symptoms

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) is now recognized as a leading cause of liver dysfunction. Gastroesophageal reflux disease (GERD) is a common disorder causing symptoms that often impair patients' quality of life. In recent years, the prevalence of both these diseases has increased, partially overlapping the rise of metabolic disorders.

AIMS

We investigated whether a relation does exist between NAFLD and GERD symptoms.

METHODS

Cross-sectional study among 206 outpatients diagnosed with NAFLD and 183 controls. We collected clinical and laboratory data, assessed severity and frequency of GERD symptoms and the esophageal endoscopic pattern.

RESULTS

The prevalence of GERD symptoms was higher in NAFLD patients than controls (61.2 vs. 27.9%, p < 0.001). We found a positive association between NAFLD and the experiencing of heartburn, regurgitation and belching. GERD symptoms were related to body mass index (BMI) and metabolic syndrome (MetS); a strong association persisted after adjustment for all the covariates (adjusted OR 3.49, 95 CI% 2.24-5.44, p < 0.001).

CONCLUSIONS

Our data show that the prevalence of GERD typical symptoms is higher in patients with NAFLD. GERD was associated with higher BMI and MetS, but not with age and diabetes type 2. NAFLD remained strongly associated with GERD, independently of a coexisting MetS status. Consistent with these findings, MetS can be considered a shared background, but cannot completely explain this correlation. We suggest NAFLD as an independent risk factor for GERD symptoms.

Perivascular adipose tissue, potassium channels, and vascular dysfunction

Perivascular adipose tissue has been recognized unequivocally as a major player in the pathology of metabolic and cardiovascular diseases. Through its production of adipokines and the release of other thus far unidentified factors, this recently discovered adipose tissue modulates vascular regulation and the myogenic response. After the discovery of its ability to diminish the vessel's response to vasoconstrictors, a new paradigm established adipose-derived relaxing factor (ADRF) as a paracrine smooth muscle cells' potassium channel opener that could potentially help combat vascular dysfunction. This review will discuss the role of ADRF in vascular dysfunction in obesity and hypertension, the different potassium channels that can be activated by this factor, and describes new pharmacological tools that can mimic the ADRF effect and thus can be beneficial against vascular dysfunction in cardiovascular disease.

Obesity-mediated association between exposure to brominated trihalomethanes and type II diabetes mellitus: an exploratory analysis

With the exception of chloroform, the rest of trihalomethanes (THM), the so-called brominated THM (Br-THM) are composed of bromine-substituted molecules with increased lipophilicity and potency to biological tissues. The THM are formed within disinfected tap water and their health effects, under research, range from cancer to adverse reproductive outcomes. However, the association between human exposures to Br-THM and the risk of developing type II diabetes mellitus (T2DM) and metabolic co-morbidities, such as obesity and non-alcoholic steatohepatitis has never been previously explored. The objective of this exploratory analysis was to address obesity-mediated associations between urinary concentrations of brominated THM and incidences of T2DM in a Cypriot adult population (n=326). First morning urine voids were collected once during summer and another time during winter while a detailed questionnaire was administered to participants. Creatinine-adjusted urinary Br-THM analyte concentrations were significantly (p<0.05) higher in T2DM cases when compared with those in healthy individuals. Multivariate logistic regression models adjusted for potential confounders showed that participants with ≥30 kg m(-2) BMI were at a higher T2DM risk (OR=8.42, 95% CI: 1.97, 45.5; p<0.01) when compared with that of normal weight participants (<25 kg m(-2)). About 4 times higher risk for developing T2DM was observed for individuals in the upper tertile of urinary Br-THM levels (OR=3.99, 95% CI: 1.07, 19.7; p<0.05) when compared with the lower tertile participants. Among the participants with BMI≥25 kg m(-2), urinary Br-THM levels were significantly (p<0.001) higher in diabetics than in healthy individuals. Ingestion and non-ingestion exposures to Br-THM deserve careful consideration in relevant epidemiological studies, as a possible environmental risk factor of T2DM.