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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adipose tissue-derived cytokines are presumably involved in obesity-associated pathologies including type 2 diabetes and atherosclerosis. Here we studied the lipopolysaccharide (LPS)-induced expression dynamics of tumor necrosis factor-alpha (TNFalpha), interleukin-6 (IL-6), IL-8 and IL-10 in human adipose tissue biopsies, in preadipocyte-derived adipocytes, and in mesenchymal stem cell (MSC)-derived adipocytes. TNFalpha, IL-6, IL-8 and IL-10 secretions by adipose tissue explants were increased 5.5-, 19.5-, 3.5- and 12.5-fold, respectively, by LPS (1 microg/mL) administration. Concordantly, IL-6 and IL-8 release was dose-dependently induced in MSC-derived adipocytes by LPS (>10 pg/mL). In contrast, TNFalpha and IL-10 remained undetectable even at the highest LPS dose (1 microg/mL) after 24h. In MSC- and preadipocyte-derived adipocytes, respectively, exposure to LPS evoked a weak and transient induction of TNFalpha mRNA whereas induction of IL-6 and IL-8 mRNA were pronounced and sustained for at least 24h. Basal glucose uptake, lipolysis and IL-6 mRNA were induced by exogenous TNFalpha (10 ng/mL) but not by IL-6 (10 ng/mL), IL-8 (100 ng/mL) and IL-10 (20 ng/mL). In this adipocyte model TNFalpha induces well known metabolic effects, but together with previous reports these data suggest that inflammation-induced TNFalpha may derive from non-adipocyte sources in adipose tissue, likely to be macrophages.
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PMID:LPS induces interleukin-6 and interleukin-8 but not tumor necrosis factor-alpha in human adipocytes. 1806 Aug 2

Obesity is a rising problem in cats. It is a risk factor for several diseases and has been linked to impaired immunity. The goal of this study was to determine the effect of body composition and effects of diet on immune function in cats. Twenty-eight short-term obese and 12 lean cats with equal gender distribution were evenly and randomly divided into two groups which were either fed a diet containing saturated (SFA) or long-chain n-3 polyunsaturated fatty acids (3-PUFA) for a period of 6 months prior to testing. Blood was collected by venipuncture from the jugular vein. Blood samples were analyzed in a double blind fashion. A complete blood count was performed and lymphocyte distribution was examined by flow cytometric analysis with specific fluorescein-conjugated subset markers. Immune function was measured as follows: the proliferative activity of different cellular fractions was tested with polyclonal mitogens such as lipopolysaccharide (LPS), phytohaemagglutinin (PHA), phorbol 12-myristate 13-acetate (PMA), Ca ionophore, and concanavalin A. Innate immune functions assessed were phagocytosis and natural killer cell (NK) cytotoxicity. A similar immune innate and adaptive immune response was elicited regardless of diet or body condition. However, there was no correlation between body condition, diet, and any of the quantitative and qualitative functional responses of the immune system. We conclude that short-term obesity and the fatty acid composition of the diet do not alter immune responses in cats.
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PMID:The effects of obesity and fatty acids on the feline immune system. 1806 76

Adipose tissue-derived cytokines (adipokines) are associated with the development of inflammation and insulin resistance. However, which adipokine(s) mediate this linkage and the mechanisms involved during obesity is poorly understood. Through proteomics and microarray screening, we recently identified lipocalin 2 (LCN 2) as an adipokine that potentially connects obesity and its related adipose inflammation. Herein we show that the levels of LCN2 mRNA are dramatically increased in adipose tissue and liver of ob/ob mice and primary adipose cells isolated from Zucker obese rats, and thiazolidinedione administration reduces LCN2 expression. Interestingly, addition of LCN2 induces mRNA levels of peroxisome proliferator-activated receptor-gamma (PPARgamma) and adiponectin. Reducing LCN2 gene expression causes decreased expression of PPARgamma and adiponectin, slightly reducing insulin-stimulated Akt2 phosphorylation at Serine 473 in 3T3-L1 adipocytes. LCN2 administration to 3T3-L1 cells attenuated TNFalpha-effect on glucose uptake, expression of PPARgamma, insulin receptor substrate-1, and glucose transporter 4, and secretion of adiponectin and leptin. When added to macrophages, LCN2 suppressed lipopolysaccharide-induced cytokine production. Our data suggest that LCN2, as a novel autocrine and paracrine adipokine, acts as an antagonist to the effect of inflammatory molecules on inflammation and secretion of adipokines.
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PMID:The role of lipocalin 2 in the regulation of inflammation in adipocytes and macrophages. 1829 40

The lipid peroxidation product 4-hydroxynonenal (4-HNE) is a signaling mediator with wide-ranging biological effects. In this paper, we report that disruption of mGsta4, a gene encoding the 4-HNE-conjugating enzyme mGSTA4-4, causes increased 4-HNE tissue levels and is accompanied by age-dependent development of obesity which precedes the onset of insulin resistance in 129/sv mice. In contrast, mGsta4 null animals in the C57BL/6 genetic background have normal 4-HNE levels and remain lean, indicating a role of 4-HNE in triggering or maintaining obesity. In mGsta4 null 129/sv mice, the expression of the acetyl-CoA carboxylase (ACC) transcript is enhanced several-fold with a concomitant increase in the tissue level of malonyl-CoA. Also, mitochondrial aconitase is partially inhibited, and tissue citrate levels are increased. Accumulation of citrate could lead to allosteric activation of ACC, further augmenting malonyl-CoA levels. Aconitase may be inhibited by 4-HNE or by peroxynitrite generated by macrophages which are enriched in white adipose tissue of middle-aged mGsta4 null 129/sv mice and, upon lipopolysaccharide stimulation, produce more reactive oxygen species and nitric oxide than macrophages from wild-type mice. Excessive malonyl-CoA synthesized by the more abundant and/or allosterically activated ACC in mGsta4 null mice leads to fat accumulation by the well-known mechanisms of promoting fatty acid synthesis and inhibiting fatty acid beta-oxidation. Our findings complement the recent report that obesity causes both a loss of mGSTA4-4 and an increase in the level of 4-HNE [Grimsrud, P. A., et al. (2007) Mol. Cell. Proteomics 6, 624-637]. The two reciprocal processes are likely to establish a positive feedback loop that would promote and perpetuate the obese state.
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PMID:Role of the electrophilic lipid peroxidation product 4-hydroxynonenal in the development and maintenance of obesity in mice. 1831 40

Obesity results from alterations in the body's regulation of energy intake, expenditure, and storage. Recent evidence, primarily from investigations in animal models, suggests that the gut microbiota affects nutrient acquisition and energy regulation. Its composition has also been shown to differ in lean vs obese animals and humans. In this article, we review the published evidence supporting the potential role of the gut microbiota in the development of obesity and explore the role that modifying the gut microbiota may play in its future treatment. Evidence suggests that the metabolic activities of the gut microbiota facilitate the extraction of calories from ingested dietary substances and help to store these calories in host adipose tissue for later use. Furthermore, the gut bacterial flora of obese mice and humans include fewer Bacteroidetes and correspondingly more Firmicutes than that of their lean counterparts, suggesting that differences in caloric extraction of ingested food substances may be due to the composition of the gut microbiota. Bacterial lipopolysaccharide derived from the intestinal microbiota may act as a triggering factor linking inflammation to high-fat diet-induced metabolic syndrome. Interactions among microorganisms in the gut appear to have an important role in host energy homeostasis, with hydrogen-oxidizing methanogens enhancing the metabolism of fermentative bacteria. Existing evidence warrants further investigation of the microbial ecology of the human gut and points to modification of the gut microbiota as one means to treat people who are over-weight or obese.
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PMID:Gut microbiota and its possible relationship with obesity. 1838 Sep 92

In rats, neonatal treatment with monosodium L-glutamate (MSG) induces several metabolic and neuroendocrine abnormalities, which result in hyperadiposity. No data exist, however, regarding neuroendocrine, immune and metabolic responses to acute endotoxemia in the MSG-damaged rat. We studied the consequences of MSG treatment during the acute phase response of inflammatory stress. Neonatal male rats were treated with MSG or vehicle (controls, CTR) and studied at age 90 days. Pituitary, adrenal, adipo-insular axis, immune, metabolic and gonadal functions were explored before and up to 5 h after single sub-lethal i.p. injection of bacterial lipopolysaccharide (LPS; 150 microg/kg). Our results showed that, during the acute phase response of inflammatory stress in MSG rats: (1) the corticotrope-adrenal, leptin, insulin and triglyceride responses were higher than in CTR rats, (2) pro-inflammatory (TNFalpha) cytokine response was impaired and anti-inflammatory (IL-10) cytokine response was normal, and (3) changes in peripheral estradiol and testosterone levels after LPS varied as in CTR rats. These data indicate that metabolic and neroendocrine-immune functions are altered in MSG-damaged rats. Our study also suggests that the enhanced corticotrope-corticoadrenal activity in MSG animals could be responsible, at least in part, for the immune and metabolic derangements characterizing hypothalamic obesity.
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PMID:Neuroendocrine, metabolic, and immune functions during the acute phase response of inflammatory stress in monosodium L-glutamate-damaged, hyperadipose male rat. 1838 67

The microbial community present in the human mouth is engaged in a complex network of diverse metabolic activities. In addition to serving as energy and building-block sources, metabolites are key players in interspecies and host-pathogen interactions. Metabolites are also implicated in triggering the local inflammatory response, which can affect systemic conditions such as atherosclerosis, obesity, and diabetes. While the genome of several oral pathogens has been sequenced, quantitative understanding of the metabolic functions of any oral pathogen at the system level has not been explored yet. Here we pursue the computational construction and analysis of the genome-scale metabolic network of Porphyromonas gingivalis, a gram-negative anaerobe that is endemic in the human population and largely responsible for adult periodontitis. Integrating information from the genome, online databases, and literature screening, we built a stoichiometric model that encompasses 679 metabolic reactions. By using flux balance approaches and automated network visualization, we analyze the growth capacity under amino-acid-rich medium and provide evidence that amino acid preference and cytotoxic by-product secretion rates are suitably reproduced by the model. To provide further insight into the basic metabolic functions of P. gingivalis and suggest potential drug targets, we study systematically how the network responds to any reaction knockout. We focus specifically on the lipopolysaccharide biosynthesis pathway and identify eight putative targets, one of which has been recently verified experimentally. The current model, which is amenable to further experimental testing and refinements, could prove useful in evaluating the oral microbiome dynamics and in the development of novel biomedical applications.
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PMID:Metabolic network model of a human oral pathogen. 1893 Nov 37

Obesity and related disorders represent states of systemic low-grade inflammation. Chemokine secretion by adipocytes may initiate leukocyte infiltration in obese adipose tissue and thus mediate an important step in the establishment of chronic immune activation. The chemokine RANTES (regulated upon activation normal T cell expressed and secreted)/CCL5 is a chemoattractant for various leukocyte subsets. This study was designed to examine whether RANTES is expressed and released by human adipocytes and how its expression is regulated. RANTES expression under basal conditions was studied in mature adipocytes. Cells were therefore challenged with lipopolysaccharide (LPS), interferon (IFN)-gamma, interleukin (IL)-4, monocyte chemoattractant protein (MCP)-1 or exposed to low oxygen pressure. RANTES was expressed and secreted constitutively in most samples of mature adipocytes from the omental and the subcutaneous depot. RANTES release was dependent on adipocyte size and also seemed to be higher from cells of obese donors. Hypoxia (4% O (2)) caused an approximately 36% increase of RANTES release. Human adipocytes express the chemokine RANTES and are thus identified as a novel cellular source of this immune mediator. LPS and IFNgamma do not seem to play a significant role for the expression of RANTES in contrast to moderate hypoxia, which points to a distinct role in the innate immune system.
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PMID:Expression and secretion of RANTES (CCL5) in human adipocytes in response to immunological stimuli and hypoxia. 1895 2

Adiponectin is an adipose-secreted hormone with anti-inflammatory properties mediated by inhibition of nuclear factor-kappaB (NF-kappaB) signaling. This study investigates whether fenofibrate alters adiponectin levels in patients with hypertriglyceridemia and the metabolic syndrome, and examines the association of adiponectin with circulating inflammatory markers and whole blood cytokine production. The effects of fenofibrate (160 mg/day) on adiponectin and other inflammatory markers were investigated in a 12-week randomized, placebo-controlled trial in 55 patients with hypertriglyceridemia (plasma triglycerides > or =1.7 mmol/l and <6.8 mmol/l), central obesity and other characteristics of the metabolic syndrome who were not receiving lipid-altering therapies. In the fenofibrate group, adiponectin levels increased from 4.10 to 4.50 microg/ml (+7.7%); in the placebo group, adiponectin levels increased by 1.8%; (P = 0.0005). In multivariate models including age, gender, and waist circumference, there were inverse correlations between changes in adiponectin and vascular cell adhesion molecule-1 (VCAM-1) (r = -0.54, P < 0.0001) and intercellular adhesion molecule-1 (ICAM-1) (r = -0.57, P < 0.0001), and C-reactive protein (CRP) (r = -0.40, P = 0.0041); lipopolysaccharide (LPS)-stimulated production of tumor necrosis factor-alpha (TNF-alpha) (r = -0.30, P = 0.035), interleukin (IL)-1beta (r = -0.44, P = 0.0016), monocyte chemotactic protein-1 (MCP-1) (r = -0.46, P = 0.001), and macrophage inflammatory protein-1alpha (MIP-1alpha) (r = -0.45, P = 0.0012). Fenofibrate (160 mg/day) raised adiponectin levels in patients with hypertriglyceridemia and the metabolic syndrome. Changes in adiponectin were significantly and inversely associated with changes in multiple inflammatory markers. These data suggest that adiponectin may contribute to the anti-inflammatory effects of fenofibrate.
Obesity (Silver Spring) 2009 Mar
PMID:Effect of fenofibrate on adiponectin and inflammatory biomarkers in metabolic syndrome patients. 1902 79

Obesity is associated with an increase in chronic, low-grade inflammation which has been implicated in the development of type 2 diabetes mellitus and cardiovascular disease. The purpose of this study was to determine whether obesity was associated with an elevation of whole blood lipopolysaccharide (LPS)-stimulated tumor necrosis factor-alpha (TNF-alpha) production. African-American women were recruited from a larger study and assigned to one of five groups based on BMI: normal weight (NORM; BMI 20-25, n = 7), overweight (OVER; BMI 25-30, n = 12), class 1 obese (OB1; BMI 30-35, n = 19), class 2 obese (OB2; BMI 35-40, n = 10), or class 3 obese (OB3; BMI >40, n = 17). Body composition was determined via a whole body dual-energy X-ray absorptiometry (DXA) scan. Venous blood samples were collected following an overnight fast (>8 h), and stimulated with five doses of LPS (Salmonella enteriditis): 80, 40, 20, 10, and 5 microg/ml for 24 h in a 37 degrees C, 5% CO(2) incubator. Following stimulation, TNF-alpha was measured using enzyme-linked immunosorbent assay. OB3 produced 365% more TNF-alpha than NORM at an LPS dose of 20 microg/ml (P < 0.05). When maximal TNF-alpha production was assessed regardless of LPS dose, OB3 produced 230% more than NORM and OVER produced 190% more than NW (P = 0.001). Total and trunk fat mass and BMI were significantly correlated with maximal TNF-alpha production and LPS = 20 microg/ml. Our findings are consistent with previous reports suggesting a relationship between increased adiposity and inflammatory marker production. This is one of the first studies to focus on African-American women, who have higher rates of obesity.
Obesity (Silver Spring) 2009 Mar
PMID:Severely obese have greater LPS-stimulated TNF-alpha production than normal weight African-American women. 1905 21


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