Expression Of Adipocytokines Research Articles

Metabolic Syndrome in Breast Cancer: Paracrine Mediators in Mammary Adipose Tissue Mediated by Metabolic Dysfunction Influence Tumour Cell Proliferation.

Abstract Introduction:Obesity and it's associated metabolic syndrome are known epidemiological risk factors for breast cancer.¹ Adipose tissue is a potent endocrine organ secreting many factors that can potentially regulate tumour growth. The breast constitutes an excellent model to determine the paracrine mediators of adiposity on breast cancer. The aim of this preliminary study was thus to describe the adipocytokine milieu in the breast and determine what influence adiposity and metabolic dysfunction played in tumour progression.Methods:Adipose conditioned media (ACM) was produced by harvesting adipose tissue from sites adjacent to (peritumoural PT) and distal (D) to tumour in 20 fresh mastectomy specimens and cultured in serum free media for 72hrs. MDA-MB 231 and MCF-7 cell lines were then cultured with this ACM for 24-48hrs. Cell survival/proliferation was determined by BrDU assay. An in depth characterisation of adipocytokine production from each adipose depot was performed using multiplex bead arrays.Results:ACM from peritumoural/distal adipose tissue promoted cell proliferation in both cell lines. The greatest proliferative effect was observed in ER+ve MCF-7 cell line relative to controls (151.9±7.3% and 150.8±9.8% in peritumoural and distal ACM respectively), compared to ER-ve MDA-MB-231 cells (111.4±5.0, 112.0±2.5%).PT ACM from metabolically unhealthy/obese patients significantly increased proliferation in MCF-7 cells, compared to normal weight cancer patients (171±12.6% vs 135.3±9.3%, p=0.034). Similarly, adipocytokine expression reflected these changes with expression differences in IL-6 (6.72±0.09, 6.31±0.16 ng/ml p=0.028), HGF (7.5±1.3, 3.98±0.43 ng/ml p=0.028).Conclusion:Peritumoural adipose tissue from metabolically unhealthy and obese patients increased cell proliferation compared to normal weight patients. Metabolic dysfunction influenced expression of several adipocytokines in ACM. A thorough analysis of this milieu should lead to a greater understanding of how obesity/metabolic dysfunction regulate tumourigenesis in breast cancer.

Abstract 5103: Perivascular Adipose Tissue in Angiotensin II Dependent Hypertension

Recent studies have suggested that perivascular adipose tissue (pvAT) is not just a mechanical scaffold for the vasculature but that it plays a critical role in vascular disease. The effects of mediators such as angiotensin II on perivascular adipose tissue however remain unknown. Accordingly, we examined the effects of chronic (14 day) angiotensin II (490ng/kg/min) infusion in mice on perivascular adipose tissue in comparison to effects on visceral (VAT) and subcutaneous (SAT) adipose tissue. Real time PCR and Western blotting showed that both AT1R and AT2R angiotensin II receptors were expressed in all studied compartments of AT but were greater in pvAT (485±90 vs. 45±18 in VAT and 3±0.7 in SAT U/ug RNA for AT1R mRNA; p<0.001). Angiotensin II infusion decreased epidydymal fat pad weight (413±45 mg vs 181±23mg; p<0.01) with concomitant increase of perivascular fat measured histologically (18±3 vs. 30±6 AU per aortic lumen; p<0.01). Interestingly, the cellularity of both pvAT and VAT increased (pvAT>>VAT) significantly but remained unchanged in SAT upon Angiotensin II infusion. Angiotensin II significantly altered adipocytokine expression in pvAT and VAT but not in SAT. Resistin levels increased in pvAT in response to angiotensin II, while leptin, visfatin and adiponectin decreased. The most significant changes were observed in inflammatory cytokines and chemokines. IL-6, TNF-a, IL-17A and were induced in pvAT to a greater degree than in VAT and were not changed by angiotensin II in SAT. Angiotensin II increased RANTES mRNA 6-fold in pvAT but not in VAT or SAT. Immunohistochemistry confirmed an increase in RANTES expression selectively in pvAT. These changes of cytokine and chemokine expression were accompanied by increased infiltration of pvAT with T lymphocytes expressing the RANTES receptor CCR5. These data indicate that angiotensin II affects adipocytokine and cytokine expression in adipose tissue and these effects are most pronounced in pvAT leading to T cell infiltration. These data indicate that the pvAT is a unique compartment of fat predisposed to angiotensin II-induced inflammation and a potential target for therapeutic intervention.

Differences in Adipocytokines and Fatty Acid Composition between Two Adipocyte Fractions of Small and Large Cells in High-Fat Diet-Induced Obese Mice

Objective: This study was conducted to compare the differences in adipocytokines and fatty acid composition between two fraction sizes of small and large cells from subcutaneous and visceral fat of mice receiving a high-fat diet (HFD). Methods: Body weight, blood glucose and cholesterol levels, and adipocyte diameter distribution were examined. Total adipocyte fractions could be separated into the small-cell fraction (SCF) and the large-cell fraction (LCF). Adipocytokine expression, fatty acid composition and stearoyl-CoA desaturase (SCD) expression were compared between SCF and LCF. Results: In HFD mice, body weight, glucose and cholesterol levels were significantly higher than in NCD mice. The adipocyte diameter of HFD mice continuously increased throughout the feeding period regardless of the fat depot. The expression of adipocytokine genes such as angiotensinogen, plasminogen activator inhibitor-1, adipsin, leptin, TNF-α and adiponectin was higher in LCF than SCF. The ratio of stearic acid to the total fatty acid content was lower in SCF than LCF, whereas oleic acid composition was higher in LCF. SCD expression was higher in LCF than SCF. Conclusion: Our results indicate that large adipocytes strongly express adipocytokine genes and show high oleic acid composition via SCD upregulation. Based on these findings, the differences in fatty acid composition between adipocyte sizes may be related to adipocytokine expression.

Effects of weight loss induced by bariatric surgery on hepatic adipocytokine expression

Adipocytokines play a key role in the pathophysiology of non-alcoholic fatty liver diseases (NAFLD). Whereas adiponectin has mainly anti-inflammatory functions, leptin, resistin and pre-B cell enhancing factor (PBEF)/Nampt/visfatin are considered as mainly pro-inflammatory mediators regulating metabolic and immune processes. We prospectively examined the effect of weight loss on systemic levels and/or hepatic expression of adiponectin/adiponectin receptors, leptin/leptin receptors, resistin and PBEF/Nampt/visfatin. Severely obese patients underwent laparoscopic adjustable gastric banding (LABG) and serum samples (n=30) were collected before, and after 6 and 12 months. Paired liver biopsies (before and 6 months after LABG) were obtained from 18 patients. Bariatric surgery improved insulin resistance, abnormal liver function tests and liver histology. Pronounced weight loss after 6 and 12 months was accompanied by a significant increase in serum adiponectin levels whereas both leptin and PBEF/Nampt/visfatin levels decreased. Resistin serum levels increased after 6 months but fell below baseline values after 12 months. Liver mRNA expression of adiponectin increased slightly after 6 months whereas leptin mRNA expression did not change. Interestingly, weight loss resulted in a significant decrease of hepatic mRNA expression of resistin, PBEF/Nampt/visfatin and both leptin receptor isoforms while expression of type 1 and 2 adiponectin receptor was not affected. Liver immunohistochemistry performed on index and follow-up liver biopsies revealed an increase in adiponectin staining, showed no effect on resistin/leptin positivity, and demonstrated a decrease in PBEF/Nampt/visfatin immunoreactivity. Weight loss after LABG surgery drives the adipocytokine milieu towards a more anti-inflammatory direction both systemically and in the liver.

Adipocytokines, Sex Hormones, and Cardiovascular Risk Factors in Postmenopausal Women: Factor Analysis of the Rancho Bernardo Study

Steroid sex hormones modulate the expression of adipocytokines implicated in the pathogenesis of athero-thrombotic cardiovascular disease. We used exploratory factor analysis to search for latent associations between circulating sex steroid hormones, adipocytokines, and cardiovascular risk factors in a well-characterized cohort of postmenopausal women. Among participants in the Rancho Bernardo community study we identified 515 Caucasian women with a mean age of 74+/-8 years and mean body mass index of 24.2+/-3.7 kg/m(2). All had intact ovaries and none was using estrogen therapy. We constructed models aiming for structural clarity and high loading of variables on individual factors. Total adiponectin loaded with major lipid subfractions (low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and fasting triglycerides) and with sex hormone-binding globulin. Leptin loaded with central obesity (waist circumference) and fasting insulin levels. Neither adipocytokine loaded with total or bioavailable testosterone or with estradiol or dehydroepiandrosterone sulfate. Sex hormones consistently loaded together on a separate factor; this co-segregation was not influenced by body mass index. Exclusion of women with diabetes did not alter these observations. In conclusion, we identified evidence of latent associations between adipocytokines and a range of cardiovascular risk factors in postmenopausal women. Our results suggest that cardiovascular risk in older women may be modulated through a hitherto unrecognized association between adiponectin, lipid subfractions, and sex hormone bioavailability.

Suppression of MafA mRNA with siRNA prevents adipose cell differentiation in 3T3-L1 cells

One of the large Mafs, MafA protein, is a strong transactivator of insulin in pancreatic beta cells. Mafs are also known to play important roles in a variety of developmental and differentiation processes in many organs and tissues. Adipocytes are highly involved in insulin actions and glucose and lipid metabolism, and their proliferation and differentiation is regulated by coordination of several signal transduction and transcriptional factors, including members of the Maf family. To explore the role of MafA in adipocytes, we modified the MafA mRNA level in cultured adipocytes by the RNA interference technique and analyzed the resulting morphological changes and changes in expression of related genes. MafA siRNA was transfected into 3T3-L1 adipocytes. Expression of MafA was confirmed by real-time PCR and Western blotting. Expression of adipocytokines and transcriptional factors was also measured by real-time PCR. Cells were examined for morphological changes and lipid accumulation by microscopy. The MafA expression level in the MafA-siRNA-transfected pre-adipocytes was reduced by approximately 30% on day 0 pre-induction and by approximately 70% on day 3 post-induction, in comparison with stop-siRNA-transfected cells. Cell growth and lipid droplet accumulation were prevented by MafA mRNA suppression, and peroxisome proliferator-activated receptor (PPAR) gamma2 and CCAAT/enhancer-binding proteins (C/EBP)alpha, both of which are transcriptional factors essential for adipocyte differentiation, were down-regulated. Expression of the genes encoding the adipocytokines, adiponectin and adipsin was also suppressed. The results suggested a possible role of the transcriptional factor MafA in regulation of adipocyte function and differentiation.

Role of grape powder extract (GPE), quercetin (QUE), and resveratrol (RSV) in attenuating markers of inflammation in primary cultures of human (pre)adipocytes

Obesity‐associated inflammation in white adipose tissue (WAT) is strongly implicated in the development of insulin resistance. GPE is rich in phenolic phytochemicals like QUE and RSV that possess anti‐inflammatory properties. Thus, we examined the ability of GPE, QUE, and RSV to attenuate tumor necrosis factor (TNF)‐α ‐mediated activation of mitogen‐activated protein kinases (MAPK), nuclear factor kappa B (NFκB) and activator protein (AP)‐1 and induction of inflammatory genes in primary cultures of human (pre)adipocytes. We found that GPE, QUE, and RSV attenuated TNF‐α ‐induced expression of inflammatory adipocytokines [i.e., interleukin (IL)‐6, IL‐1β, IL‐8], markers of macrophage recruitment into WAT [i.e., monocyte chemoattractant protein (MCP)‐1], and negative regulators of insulin sensitivity [i.e., protein tyrosine phosphatase (PTP)‐1B]. Furthermore, we found that GPE and QUE attenuated TNF‐α ‐activated MAPK (i.e., ERK1/2, JNK1/2), NFκB, and AP‐1 (i.e., c‐Jun). RSV, however, only modestly attenuated TNFα‐activation of NFκB and c‐Jun, and had no effect on TNF‐α ‐activation of ERK1/2 and JNK1/2. Taken together, these data suggest that GPE, QUE, and RSV attenuate TNF‐α ‐mediated inflammation in primary cultures of human (pre)adipocytes by different upstream mechanisms. (Funded by the WB Kellogg Institute for Food and Nutrition Research; Grape Powder supplied by the CA Table Grape Com.)Grant Funding SourceWB Kellogg Institute for Food and Nutrition Research

Asymmetrical dimethylarginine triggers lipolysis and inflammatory response via induction of endoplasmic reticulum stress in cultured adipocytes

Protein energy wasting, a state of decreased stores of body protein and fat, is a risk factor for mortality in advanced chronic kidney disease (CKD). Little is known about the mechanism underlying loss of fat in CKD. Accumulation of asymmetric dimethylarginine (ADMA) is prevalent in advanced CKD. Here we assessed the effect of ADMA on cellular perturbation in cultured 3T3-L1 adipocytes. Exposure of adipocytes to ADMA induced lipolysis and decreased perilipin A, with no alteration of lipases expression or activity. ADMA treatment also upregulated the expression of inflammatory adipocytokines via activation of nuclear factor-kappaB (NF-kappaB). Blocking the inflammatory responses with NF-kappaB inhibitor partly inhibited the ADMA-induced lipolysis. Furthermore, ADMA treatment triggered endoplasmic reticulum (ER) stress, revealed by phosphorylation of PKR-like eukaryotic initiation factor 2alpha kinase, eukaryotic translational initiation factor 2alpha, c-Jun NH2-terminal kinase, and overexpression of glucose-regulated protein 78. Treatment with ER stress inhibitor completely abolished the ADMA-induced lipolysis and inflammatory responses. Moreover, conditioned medium from the ADMA-treated adipocytes increased protein degradation in cultured C2C12 myotubes, suggesting that the ADMA-induced adipocyte perturbation may promote skeletal muscle proteolysis. These data suggest that elevated ADMA promoted the adipocyte perturbation through induction of ER stress, which might have implication for protein energy wasting in CKD.

The effects of soy isoflavone on insulin sensitivity and adipocytokines in insulin resistant rats administered with high-fat diet

The effects of soy isoflavone (SIF) on insulin sensitivity and adipocytokines in high-fat-diet-induced insulin resistant (IR) rats were studied. Male Sprague Dawley rats (n = 80) were randomly assigned into a basal diet fed group and high-fat diet fed group. The high-fat-diet-induced IR rats were assigned into IR model control group and three SIF-treated groups with different dosages. Thirty days later, the fasting blood glucose, insulin and adipocytokines in serum and mRNA expressions of adipocytokines in perirenal white adipose tissue were measured. The Homeostasis Model Assessment of IR was calculated. The administration of 450 mg kg−1 d−1 SIF decreased the body weights and depositions of visceral adipose tissue as well as improved insulin resistance in high-fat-diet-induced IR rats. The mechanisms were associated with SIF regulating the expression of adipocytokines, including adiponectin, leptin, resistin and TNF-α. SIF supplements may have favourable effects on insulin resistance in high-fat-diet-induced IR rats.

Increasing adiposity in normal ovulatory women affects adipocytokine expression in subcutaneous and visceral abdominal fat

Objective To determine which adipocytokines are differentially expressed as a function of body mass index (BMI), to compare expression of adipocytokines in abdominal subcutaneous and omental fat, and to correlate these findings with serum levels, BMI, and parameters of insulin resistance. Methods Serum and subcutaneous (sc) and omental (om) tissue were obtained from lean and obese ovulatory women undergoing gynecologic surgery. We determined adipocytokine expression in sc versus om abdominal fat and related this to increasing BMI. Results Serum leptin was higher and adiponectin lower in overweight subjects. Adipocytokines had higher expression in sc abdominal versus om adipose tissue with the most significant difference observed for leptin ( P = 0.01). As BMI increased, sc leptin expression increased and adiponectin expression decreased. The leptin/adiponectin ratio correlated significantly with BMI (R = 0.84, P = 0.0001). Conclusion Increased adipocytokine expression correlates with BMI. Abdominal sc tissue has greater adipocytokine expression overall. The serum leptin/adiponectin ratio is highly correlated with BMI. These data may help in our understanding of how obesity affects women in a variety of ways.

Hypoxia upregulates the expression of angiopoietin‐like‐4 in human articular chondrocytes: Role of angiopoietin‐like‐4 in the expression of matrix metalloproteinases and cartilage degradation

The objective of this article was to investigate the role and expression of a novel adipocytokine, angiopoietin-like-4 (ANGPTL4), in arthropathy. Human chondrocytes were obtained from articular cartilage of patients with rheumatoid arthritis (RA) and osteoarthritis (OA), who underwent total knee or hip arthroplasty. Isolated chondrocytes were cultured under hypoxic (95% N(2), 5% CO(2)) or normoxic conditions. The effects of hypoxia on ANGPTL4 expression were determined by real-time reverse transcription polymerase chain reaction and Western blot analysis. We examined the role of ANGPTL4 using small interference RNA or by stimulating chondrocytes with recombinant ANGPTL4 protein. ANGPTL4 expression in the articular cartilage specimens was examined by immunohistochemistry. Hypoxia induced a significant increase in ANGPTL4 production (p < 0.05). Incubation of chondrocytes in vitro with recombinant ANGPTL4 enhanced the expression of matrix metalloproteinase (MMP)-1 and MMP-3. Downregulation of ANGPTL4 mRNA expression by siRNA diminished the expression of MMP-1, but not that of MMP-3, suggesting that each proteinase has a distinct response to ANGPTL4. Although the in vitro responses of chondrocytes to hypoxia were similar between RA and OA samples, the in vivo expression of ANGPTL4 had unique disease-specific patterns, suggesting differences in oxygen tension in vivo. Human chondrocytes expressed ANGPTL4 and the expression was enhanced by hypoxia. ANGPTL4 might modulate cartilage metabolism by regulating MMPs.

S1294 Role of Corticotropin-Releasing Factors in Pathogenesis of NSAID-Induced Small Intestinal Lesions in Rats

G A A b st ra ct s tissue concentrations of adipocyte hormones and ghrelin in trinitrobenzene sulphonic acid (TNBS) induced colitis before and after anti TNF treatment in rats. METHODS: Forty Sprague Dawley rats were divided into 1. Control, 2. Infliximab (IFX), 3.TNBS, 4.TNBS&IFX groups. Colitis was induced by intrarectal TNBS in groups 3&4 and physiological saline (PS) in groups 1&2. Infliximab (IFX) 5 mg/kg iv or PS infusion were given in the groups 2&4 and in the groups 1&3 respectively, on day 3 via jugular vein. Rats were decapitated on day 6. Blood, mesenteric fat and colonic samples were obtained. Leptin, adiponectin, resistin, ghrelin, IL-6, TNF-α were determined in serum by ELISA, and in tissue by immunohistochemistry semiquantitatively. Macroscopic and histological inflammation was scored. Myeloperoxidase (MPO), malonyldialdehyde (MDA) and glutathione (GSH) levels were determined in tissue homogenates. RESULTS: TNBS led to colitis which was ameliorated by IFX macroscopically and histopathologically. MPO andMDAwere increased in the colon andmesenteric fat in colitis whereas GSH was decreased. IFX reverted effects of TNBS on MPO and MDA, increased GSH levels. There were no changes in serum levels of adipocytokines except adiponectin in the TNBS group. The effects of TNBS and IFX on tissue cytokine immunoexpressions were expressed as median (range) and depicted in the table. CONCLUSION: Tissue expression of adipocytokines reflects inflammatory activity more accurately than serum level does. Decreased adiponectin, resistin and ghrelin levels in the mesenteric tissue in the TNBS group may support their anti-inflammatory role. Colonic expressions were in parallel with that of the mesentery except resistin. Paradoxical expression of resistin in the colon and mesentery may mandate to investigate if resistin has at least dual actions in those tissues not necessarily related to the inflammation. The mechanisms of action of anti-TNF agent to alleviate the inflammation and to reduce oxidative stress do not involve adipocytokines in this experimental setting.

95 MONOCYTE CHEMOATTRACTANT PROTEIN-1 (MCP-1) IS REQUIRED FOR THE DEVELOPMENT OF INFLAMMATION, OXIDATIVE DAMAGE AND FIBROSIS IN MURINE STEATOHEPATITIS

as treatments for steatohepatitis. The mechanisms implicated remain poorly understood. Activation of PPARg induces expression of adiponectin, an anti-inflammatory and insulin-sensitising adipocytokine. Upon binding to specific receptors on liver cells, adiponectin activates the AMP-activated protein kinase (AMPK), stimulates b-oxidation and represses hepatic de novo lipogenesis. Also, adiponectin, through PPARa, activates fat oxidation and inhibits inflammatory reaction. Here we tested the hypothesis that the beneficial effect of PGZ on steatohepatitis results from reduced hepatic fat accumulation due to adiponectin-dependent stimulation of AMPK and PPARa. Methods: Mice lacking adiponectin (adipo−/−), the AMPK catalytic subunit alpha1 (AMPKa1−/−) and their respective littermates were fed a methionine and choline (MCD) deficient diet, supplemented or not with pioglitazone 0.01%. Histopathology, hepatic lipid content, serum adiponectin levels were assessed. In liver tissues, we evaluated AMPK (total, a1, a2) activities, proteins and mRNA levels, PPARa mRNA and the expression of downstream targets of AMPK or PPARa. Results: In wt mice, PGZ reduces the severity of MCD diet-induced steatohepatitis, while it increased circulating levels of adiponectin. By contrast, in adiponectin−/− mice, PGZ did not alter the severity of steatohepatitis. AMPKa1−/− mice and their littermates were genetically less sensitive to dietary steatohepatitis than C57 mice. In AMPKa1−/− mice fed the MCD diet, PGZ did not reduce the severity of steatohepatitis, although it significantly increased serum adiponectin levels. In wt mice, PGZ almost completely repressed the expression and activation of SREBP1c, a key transcription factor for de novo lipogenesis and downstream target of AMPK. This effect of PGZ was lacking in adiponectin−/− and in AMPKa1−/− mice. In the strains analysed, PGZ did not alter the expression of PPARa or of its downstream targets implicated in the regulation of lipid oxidation. In conclusion, we showed that the preventive effect of PGZ on MCD-induced steatohepatitis is dependent on the up-regulation of adiponectin. While the adiponectin-PPARa-boxidation axis does not appear to be implicated, our data strongly suggest that adiponectin produces its effect by controlling the expression and activity of SREBP-1c via the activation of the AMPK complex.

The Effects of D-Chiro-Inositol on Glucose Metabolism in 3T3-L1 Cells

Background: The target of the treatment of metabolic syndrome and diabetes is an improvement of insulin resistance. D-chiro-inositol (DCI) plays a role in a phospholipid mediating intracellular insulin action. In the previous studies, the urine level of DCI were decreased in the diabetic animal with insulin resistance. Some clinical studies showed that DCI improved a glucose level and HbA1c. Therefore we studied the relationship between DCI and glucose metabolism, especially insulin resistance. Methods: To investigate the mechanism of DCI affecting the glucose metabolism, we examined the effects of DCI on 2-deoxyglucose uptake, gene expression of adipocytokines and AMPK pathway by using RT-PCR and western blot in 3T3-L1 cells. Results: Insulin-stimulated 2-deoxyglucose uptake increased in DCI-treated cells by about 1.2-fold (relative to the control) and was inhibited by phosphoinositide 3-kinase (PI3 Kinase) inhibitors (Wortmanin, LY294002) and AMPK inhibitor (STO-609). In Western blot analysis, it didn't show the difference of phosphorylation of Akt and AMPK between DCI-treated group and control in 3T3-L1 cells. However, DCI decreased the gene expression of resistin in 3T3-L1 cells. Conclusion: DCI may involve other pathway of insulin signaling, but not PI 3 Kinase and AMPK signaling pathways and it may be useful in managing metabolic syndrome by improving insulin resistance through increasing glucose uptake and decreasing resistin relevant to insulin resistance. (KOREAN DIABETES J 32:196-203, 2008)

Cyanidin 3-glucoside ameliorates hyperglycemia and insulin sensitivity due to downregulation of retinol binding protein 4 expression in diabetic mice

Adipocyte dysfunction is strongly associated with the development of obesity and insulin resistance. It is accepted that the regulation of adipocytokine expression is one of the most important targets for the prevention of obesity and improvement of insulin sensitivity. In this study, we have demonstrated that anthocyanin (cyanidin 3-glucoside; C3G) which is a pigment widespread in the plant kingdom, ameliorates hyperglycemia and insulin sensitivity due to the reduction of retinol binding protein 4 (RBP4) expression in type 2 diabetic mice. KK-A y mice were fed control or control +0.2% of a C3G diet for 5 weeks. Dietary C3G significantly reduced blood glucose concentration and enhanced insulin sensitivity. The adiponectin and its receptors expression were not responsible for this amelioration. C3G significantly upregulated the glucose transporter 4 (Glut4) and downregulated RBP4 in the white adipose tissue, which is accompanied by downregulation of the inflammatory adipocytokines (monocyte chemoattractant protein-1 and tumor necrosis factor-α) in the white adipose tissue of the C3G group. These findings indicate that C3G has significant potency in an anti-diabetic effect through the regulation of Glut4-RBP4 system and the related inflammatory adipocytokines.

Chronic Ethanol‐Induced Insulin Resistance Is Associated With Macrophage Infiltration Into Adipose Tissue and Altered Expression of Adipocytokines

Chronic ethanol consumption disrupts glucose homeostasis and is associated with the development of insulin resistance. While adipose tissue and skeletal muscle are the two major organs utilizing glucose in response to insulin, the relative contribution of these two tissues to impaired glucose homeostasis during chronic ethanol feeding is not known. As other models of insulin resistance, such as obesity, are characterized by an infiltration of macrophages into adipose tissue, as well as changes in the expression of adipocytokines that play a central role in the regulation of insulin sensitivity, we hypothesized that chronic ethanol-induced insulin resistance would be associated with increased macrophage infiltration into adipose tissue and changes in the expression of adipocytokines by adipose tissue. Male Wistar rats were fed a liquid diet containing ethanol as 36% of calories or pair-fed a control diet for 4 weeks. The effects of chronic ethanol feeding on insulin-stimulated glucose utilization were studied using the hyperinsulinemic-euglycemic clamp technique, coupled with the use of isotopic tracers. Further, macrophage infiltration into adipose tissue and expression of adipocytokines were also assessed after chronic ethanol feeding. Hyperinsulinemic-euglycemic clamp studies revealed that chronic ethanol feeding to rats decreased whole-body glucose utilization and decreased insulin-mediated suppression of hepatic glucose production. Chronic ethanol feeding decreased glucose uptake in epididymal, subcutaneous, and omental adipose tissue during the hyperinsulinemic-euglycemic clamp, but had no effect on glucose disposal in skeletal muscle. Chronic ethanol feeding increased the infiltration of macrophages into epididymal adipose tissue and changed the expression of mRNA for adipocytokines: expression of mRNA for monocyte chemoattractant protein 1, tumor necrosis factor alpha, and interleukin-6 were increased, while expression of mRNA for retinol binding protein 4 and adiponectin were decreased in epididymal adipose tissue. These data demonstrate that chronic ethanol feeding results in the development of insulin resistance, associated with impaired insulin-mediated suppression of hepatic glucose production and decreased insulin-stimulated glucose uptake into adipose tissue. Chronic ethanol-induced insulin resistance was associated with increased macrophage infiltration into adipose tissue, as well as changes in the expression of adipocytokines by adipose tissue.

REGULATORY EFFECTS OF ESTROGEN AND PROGESTERONE ON THE ADIPOSE RESISTIN EXPRESSION

Resistin, a hormone secreted by adipocytes, is suggested to be an important link between obesity and diabetes. In addition, resistin gene expression increases during adipogenesis, and its serum levels are elevated in both genetically or diet-induced obese mice. To elucidate the role of resistin, the endocrine mechanisms that regulate resistin expression will be remarkable. Several studies revealed that resistin expression is regulated by hormone, including glucocorticoids, endothelin-1, etc. Gender difference in resistin expression was also reported, the expression was higher in male than female mice, and was significant enhanced after testosterone treatment in males, but not in females. In addition to resistin, estrogen has been implicated in the regulation of adipocytokines expression and secretion. Progesterone is another sex hormone possessing pivotal physiological functions in estrus cycle. A cluster of studies strongly indicated the regulatory effect of progesterone on estrogen action in various aspects, including neuro-protection, vasodilatation, and carbohydrate metabolism. We hypothesized that the resistin expression is co-regulated by both estrogen and progesterone. The aim of this study was to evaluate the regulatory effect of estrogen and progesterone on adipocyte resistin gene expression in ovariectomized (OVX) rats, isolated rat adipocytes and 3T3-L1 adipocytes in vitro. Our preliminary results show that subcutaneous injection of estradiol benzoate (EB) reduced resistin mRNA levels in adipocytes isolated from the inguinal, parametrial, perirenal, retroperitoneal, or periovarian fat deposits of OVX rats, while an in vitro study showed that estradiol treatment decreased resistin mRNA levels in cultured rat adipocytes. Both in vivo and in vitro studies show that progesterone (P4) has no regulatory effect on resistin mRNA expression in rat adipocytes. In 3T3-L1 adipocytes, both EB and P4 have no effect on resistin mRNA expression. These data suggest that estrogen is a pivotal regulator of resistin gene expression. The underlying mechanism mediate EBregulated resistin expression will be explored in the further studies. (poster)

Subcutaneous and omental fat expression of adiponectin and leptin in women with polycystic ovary syndrome

To assess message expression of adiponectin and leptin in visceral and SC fat in women with polycystic ovary syndrome (PCOS) and in control women. Prospective clinical trial. Academic medical centers in Mexico City, Mexico and New York, New York. Women with PCOS and control women. Surgical biopsies of visceral (omental) and subcutaneous (SC) adipose tissue, fasting blood samples, and ultrasound measurements of visceral and SC fat. Messenger RNA assessment of adiponectin and leptin in adipose tissue samples; serum measurements of adiponectin, leptin, glucose, insulin, and hormone levels; measurements of fat quantity by ultrasound. Correlative analyses as well as comparisons between women with PCOS and control women were performed. Confirming previous data, women with PCOS had more insulin resistance, similar serum leptin, but lower serum adiponectin compared with control women. When control women were divided into quartiles by body mass index (BMI), messenger RNA expression of leptin and adiponectin decreased with increasing BMI. Adiponectin and leptin expression was significantly lower in women with PCOS; in weight-matched patients and control women, leptin and adiponectin expression was statistically significantly lower in SC tissue, and adiponectin expression was statistically significantly lower in omental tissue in women with PCOS. In control women, there was greater expression in SC tissue compared with in visceral tissue. There were significant negative correlations between visceral and SC fat mass by both ultrasound as well as adiponectin and leptin expression in women with PCOS. Serum adiponectin correlated statistically significantly with visceral adiponectin expression (r = 0.64) in women with PCOS, and there was a statistically significant correlation between SC adiponectin expression and the Quantitative Insulin-Sensitivity Check Index as a marker of insulin resistance (r = 0.43). Adipocytokine expression in fat tissue appears to be down-regulated by an increased fat mass; this is particularly evident in the case of adiponectin expression in women with PCOS. It is probable that insulin resistance is a factor that may contribute, in part, to these findings.

Role of adipocytokines in hepatic fibrogenesis

Obesity and insulin resistance are the key factors for progression of hepatic fibrosis in various chronic liver diseases including non-alcoholic steatohepatitis (NASH). Recently it has been shown that leptin plays a pivotal role in development of hepatic fibrosis. Leptin promotes hepatic fibrogenesis through upregulation of transforming growth factor-beta in Kupffer cells and sinusoidal endothelial cells. Further, leptin facilitates proliferation and prevents apoptosis of hepatic stellate cells. There is a paradox, however, in that ob/ob mice and Zucker rats, which are the obese and diabetic strains, had minimal profibrogenic responses in the liver, most likely because they lack leptin and its receptors. To establish a more clinically relevant model to study the mechanism of fibrogenesis under steatohepatitis, fatty changes and profibrogenic responses in the liver caused by methionine-choline deficiency (MCD) were investigated in the KK-A(y) mouse, which is an obese and diabetic strain. KK-A(y) mice developed more severe hepatic steatosis, inflammation and fibrosis induced by an MCD diet as compared to C57Bl/6 controls. Importantly, KK-A(y) mice lack physiological upregulation of adiponectin levels, suggesting that adiponectin plays a pivotal role not only in regulation of insulin sensitivity but also in modulation of inflammatory and profibrogenic responses in dietary steatohepatitis. Collectively, these findings support the hypothesis that the balance of adipocytokine expression is a key regulator for the progression of hepatic fibrosis in the setting of steatohepatitis.

Adipose Tissue Hypoxia in Obesity and Its Impact on Adipocytokine Dysregulation

Obesity is linked to a variety of metabolic disorders, such as insulin resistance and atherosclerosis. Dysregulated production of fat-derived secretory factors, adipocytokines, is partly responsible for obesity-linked metabolic disorders. However, the mechanistic role of obesity per se to adipocytokine dysregulation has not been fully elucidated. Here, we show that adipose tissue of obese mice is hypoxic and that local adipose tissue hypoxia dysregulates the production of adipocytokines. Tissue hypoxia was confirmed by an exogenous marker, pimonidazole, and by an elevated concentration of lactate, an endogenous marker. Moreover, local tissue hypoperfusion (measured by colored microspheres) was confirmed in adipose tissue of obese mice. Adiponectin mRNA expression was decreased, and mRNA of C/EBP homologous protein (CHOP), an endoplasmic reticulum (ER) stress-mediated protein, was significantly increased in adipose tissue of obese mice. In 3T3-L1 adipocytes, hypoxia dysregulated the expression of adipocytokines, such as adiponectin and plasminogen activator inhibitor type-1, and increased the mRNAs of ER stress marker genes, CHOP and GRP78 (glucose-regulated protein, 78 kD). Expression of CHOP attenuated adiponectin promoter activity, and RNA interference of CHOP partly reversed hypoxia-induced suppression of adiponectin mRNA expression in adipocytes. Hypoxia also increased instability of adiponectin mRNA. Our results suggest that hypoperfusion and hypoxia in adipose tissues underlie the dysregulated production of adipocytokines and metabolic syndrome in obesity.