Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0028754 (obesity)
 124,988 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The aim of this study was to determine the relationship between serum magnesium and TNF-alpha levels in obese subjects. A cross-sectional population based study that included 192 non-diabetic, non-hypertensive subjects allocated in three categories of body mass index (BMI) <25; > or =25 to <30 kg/m2; and > or =30 kg/m2. Elevation of TNF-alpha levels was defined by serum levels > or =3.5 pg/mL, and low serum magnesium by levels < or = 0.74 mmol/L. Multivariate odds ratios (OR) adjusted by age, HOMA-IR index, and glucose tolerance status are presented. Obese subjects exhibited higher serum concentration of TNF-alpha (p = 0.002) and lower serum magnesium levels (p < 0.0001) than lean and overweight subjects. Ninety-one (47.4%) subjects showed elevated levels of TNF-alpha, of them 7 (10.9%), 31 (48.4%), and 43 (67.2%) in the groups with BMI <25, > or = 25 to < 0, and >> or =0 kg/m2, respectively. Multivariate OR between low serum magnesium and TNF-alpha levels in obese subjects was of 1.8, Cl95% 1.2-9.1, P = 0.001, whereas in the lean and overweight individuals of 1.1, Cl95% 0.7-8.7, P = 0.12, and 1.3, Cl95% 0.9-10.8, P = 0.09, respectively. These data shows that low serum magnesium levels and elevated TNF-alpha are related in the obese subjects. It will be necessary to conduct more studies in order to add new data on this issue.
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PMID:Elevated concentrations of TNF-alpha are related to low serum magnesium levels in obese subjects. 1572 67

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a ligand-dependent nuclear receptor and regulates adipogenesis and fat metabolism. PPARgamma is activated by fatty acid derivatives and some synthetic compounds such as the thiazolidinediones. In addition, certain cytokines were known to affect the transactivation function of PPARgamma. However, the molecular mechanism of the functional interaction between PPARgamma and cytokine signaling remains unclear. We found that combined treatment of PPARgamma and cytokines (IL-1 or TNF-alpha) inhibited adipogenesis and induced osteoblastgenesis in bone marrow-derived mesenchymal stem cells. Furthermore, we showed that the ligand dependent transactivation function of PPARgamma was suppressed by IL-1 and TNF-alpha. This suppression was mediated through NF-kappaB activated by the TAK1/TAB1-NIK cascade, a downstream cascade triggered with IL-1 or TNF-alpha signaling. Thus, we have identified a molecular mechanism of functional cross-talk between PPARgamma and cytokine signaling that may provide a theoretical basis for development of novel therapeutical strategies and design of novel compounds for treatment of obesity, diabetes, and some other chronic diseases.
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PMID:Nuclear receptors as targets for drug development: crosstalk between peroxisome proliferator-activated receptor gamma and cytokines in bone marrow-derived mesenchymal stem cells. 2414 68

TNF-alpha is a mediator of insulin resistance in sepsis, obesity, and type 2 diabetes and is known to impair insulin signaling in adipocytes. Akt (protein kinase B) is a crucial signaling mediator for insulin. In the present study we examined the posttranslational mechanisms by which short-term (<6-h) exposure of 3T3-L1 adipocytes to TNF-alpha decreases Akt levels. TNF-alpha treatment both increased the ubiquitination of Akt and decreased its protein level. The decrease in protein was associated with the presence of an (immunoreactive) Akt fragment after TNF-alpha treatment, indicative of Akt cleavage. The broad-spectrum caspase inhibitor t-butoxycarbonyl-Asp(O-Me)-fluoromethyl ketone markedly suppressed these effects of TNF-alpha. The caspase-6 inhibitor Z-Val-Glu(OMe)-Ile-Asp(OMe)-CH(2)F potently suppressed Akt ubiquitination, degradation, and fragment formation, whereas the proteasome inhibitor Z-Leu-Leu-Leu-CHO modestly attenuated the decline in Akt levels. Exposure to TNF-alpha also enhanced the association of Akt with an E3 ligase activity. Adipocytes preexposed to TNF-alpha for 5 h and then stimulated with insulin for 30 min exhibited decreased levels of Akt, phosphorylated Akt, as well as phosphorylated Mdm2, which is a known direct substrate of Akt, and glucose uptake. Caspase inhibition attenuated these inhibitory effects of TNF-alpha. Collectively, our results suggest that TNF-alpha induces the caspase-dependent degradation of Akt via the cleavage and ubiquitination of Akt, which results in its degradation through the 26S proteasome. Furthermore, the caspase- and proteasome-mediated degradation of Akt due to TNF-alpha exposure leads to impaired Akt-dependent insulin signaling in adipocytes. These findings expand the mechanism by which TNF-alpha impairs insulin signaling.
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PMID:Tumor necrosis factor-{alpha} decreases Akt protein levels in 3T3-L1 adipocytes via the caspase-dependent ubiquitination of Akt. 1574 49

White adipose tissue (WAT) is the source of pro- and anti-inflammatory cytokines and we have recently shown that this tissue is a major source of the anti-inflammatory interleukin (IL)-1 receptor antagonist (IL-1Ra). We now aimed at identifying additional adipose-derived cytokines, which might serve as regulators of IL-1Ra. We demonstrate here for the first time that the antiinflammatory cytokine IL-10 is secreted by human WAT explants and that it is up-regulated by LPS and TNF-alpha in vitro, as well as in obesity in humans (2- and 6-fold increase in subcutaneous and visceral WAT, respectively) and rodents (4-fold increase).
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PMID:Adipose tissue is a regulated source of interleukin-10. 1574 27

In experimental models, adiponectin improves and tumor necrosis factor alpha (TNF- alpha ) impairs insulin action, and the expression of these adipocytokines seems to have a reciprocal regulation. The aim was to examine whether in a cross-sectional study, associations supporting this concept may be found in 58-year-old clinically healthy men, and also the relation to C-reactive protein (CRP). In 102 men, euglycemic hyperinsulinemic clamp was used to assess glucose infusion rate (GIR). Total body fat (dual-energy x-ray absorptiometry), plasma adiponectin (radioimmunoassay), TNF-alpha , and CRP (enzyme-linked immunosorbent assay) were measured. Adiponectin correlated positively to GIR (r=0.33, P<.001) and negatively to total fat mass (r=-0.29, P=.004), whereas TNF- alpha showed reverse associations (r=-0.31, P<.01, and r=0.31, P<.01). Adiponectin and TNF- alpha were negatively correlated (-0.28, P=.006). An interaction term (TNF- alpha /adiponectin ratio) and body fat together explained 31.3% (P<.001) in GIR variability. The odds ratio for having insulin resistance was 9.3 (95% CI, 2.2-38.9) in subjects with TNF-alpha values above and adiponectin levels below the median, as compared to subjects with TNF- alpha values below and adiponectin levels above the median. Total fat and TNF-alpha , but not adiponectin, were significantly associated with log CRP (R2=20%, P<.001). In conclusion, this study in man showed that plasma adiponectin and TNF-alpha were independently and reversely associated with insulin resistance. C-reactive protein levels were related to TNF-alpha and obesity.
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PMID:The reciprocal association of adipocytokines with insulin resistance and C-reactive protein in clinically healthy men. 1579 48

Orlistat is an antiobesity drug with a well documented efficacy in weight reduction and weight maintenance. Weight reduction with orlistat has been associated with a favourable effect on obesity-related cardiovascular risk factors. Orlistat treatment is associated with a reduction in serum insulin levels. Moreover, orlistat reduces the incidence of type 2 diabetes in patients with impaired glucose tolerance and lowers the required dose of metformin, sulfonylureas and insulin in patients with type 2 diabetes. Furthermore, orlistat can reduce total and low density lipoprotein (LDL) cholesterol levels and improve postprandial triglyceridemia, as well as the low density lipoprotein cholesterol/high density lipoprotein cholesterol ratio (LDL/HDL ratio). Moreover, orlistat appears to have a favourable effect on some inflammatory markers, such as TNF-alpha and interleukin-6 and has a time-depended effect on some haemostatic factors.
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PMID:The effects of orlistat on metabolic parameters and other cardiovascular risk factors. 1580 8

BACKGROUND: Recent findings have established an association between obesity and immune dysfunction. However, most of the studies investigating the effects of obesity on immune function have been carried out in genetically obese rodent models. Since human obesity is mostly due to intake of a high fat diet and decreased energy expenditure, we asked whether immunological defects also occur in diet-induced obesity. Specifically, we focused on the function of monocytes and macrophages, as these cells are thought to be involved in the low-grade inflammation present in obesity. METHODS: Male Sprague-Dawley rats were fed a high-fat or a standard chow diet for either 2 or 10 weeks. At the end of the intervention period animals were anaesthetised, blood collected for determination of plasma mediator concentrations and lipopolysaccharide (LPS) stimulated production of TNF-alpha by monocytes. LPS stimulated production of TNF-alpha in alveolar macrophages was also determined. RESULTS: High-fat feeding for either 2 or 10 weeks resulted in significant increases in fat mass and serum leptin. Although increased serum leptin has previously been linked to modulation of innate immunity, we found no significant difference in the LPS stimulated production of TNF-alpha by either blood monocytes or alveolar macrophages between the dietary groups. Furthermore, we failed to find a significant increase in circulating TNF-alpha concentrations in obese animals, as reported for genetically obese animals. CONCLUSION: Our data suggest that defects in innate immune function observed in genetically obese animals are not mimicked by dietary obesity, and may more likely reflect the gross abnormality in leptin function of these models. Further work is required delineate the effects of dietary obesity on inflammatory state and immune function.
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PMID:Unaltered TNF-alpha production by macrophages and monocytes in diet-induced obesity in the rat. 1581 57

The adipokine resistin is suggested to be an important link between obesity and insulin resistance. In the present study, we assessed the impact of resistin as inflammatogenic cytokine in the setting of arthritis. In vitro experiments on human PBMC were performed to assess cytokine response and transcription pathways of resistin-induced inflammation. Proinflammatory properties of resistin were evaluated in animal model by intra-articular injection of resistin followed by histological evaluation of the joint. Levels of resistin were assessed by ELISA in 74 paired blood and synovial fluid samples of patients with rheumatoid arthritis. Results were compared with the control group comprised blood samples from 34 healthy individuals and 21 synovial fluids from patients with noninflammatory joint diseases. We now show that resistin displays potent proinflammatory properties by 1) strongly up-regulating IL-6 and TNF-alpha, 2) responding to TNF-alpha challenge, 3) enhancing its own activity by a positive feedback, and finally 4) inducing arthritis when injected into healthy mouse joints. Proinflammatory properties of resistin were abrogated by NF-kappaB inhibitor indicating the importance of NF-kappaB signaling pathway for resistin-induced inflammation. Resistin is also shown to specifically accumulate in the inflamed joints of patients with rheumatoid arthritis and its levels correlate with other markers of inflammation. Our results indicate that resistin is a new and important member of the cytokine family with potent regulatory functions. Importantly, the identified properties of resistin make it a novel and interesting therapeutic target in chronic inflammatory diseases such as rheumatoid arthritis.
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PMID:Resistin, an adipokine with potent proinflammatory properties. 1584 82

Inflammation contributes to insulin resistance in diabetes and obesity. Mouse Pelle-like kinase (mPLK, homolog of human IL-1 receptor-associated kinase (IRAK)) participates in inflammatory signaling. We evaluated IRS-1 as a novel substrate for mPLK that may contribute to linking inflammation with insulin resistance. Wild-type mPLK, but not a kinase-inactive mutant (mPLK-KD), directly phosphorylated full-length IRS-1 in vitro. This in vitro phosphorylation was increased when mPLK was immunoprecipitated from tumor necrosis factor (TNF)-alpha-treated cells. In NIH-3T3(IR) cells, wild-type mPLK (but not mPLK-KD) co-immunoprecipitated with IRS-1. This association was increased by treatment of cells with TNF-alpha. Using mass spectrometry, we identified Ser(24) in the pleckstrin homology (PH) domain of IRS-1 as a specific phosphorylation site for mPLK. IRS-1 mutants S24D or S24E (mimicking phosphorylation at Ser(24)) had impaired ability to associate with insulin receptors resulting in diminished tyrosine phosphorylation of IRS-1 and impaired ability of IRS-1 to bind and activate PI-3 kinase in response to insulin. IRS-1-S24D also had an impaired ability to mediate insulin-stimulated translocation of GLUT4 in rat adipose cells. Importantly, endogenous mPLK/IRAK was activated in response to TNF-alpha or interleukin 1 treatment of primary adipose cells. In addition, using a phospho-specific antibody against IRS-1 phosphorylated at Ser(24), we found that interleukin-1 or TNF-alpha treatment of Fao cells stimulated increased phosphorylation of endogenous IRS-1 at Ser(24). We conclude that IRS-1 is a novel physiological substrate for mPLK. TNF-alpha-regulated phosphorylation at Ser(24) in the pleckstrin homology domain of IRS-1 by mPLK/IRAK represents an additional mechanism for cross-talk between inflammatory signaling and insulin signaling that may contribute to metabolic insulin resistance.
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PMID:Phosphorylation of Ser24 in the pleckstrin homology domain of insulin receptor substrate-1 by Mouse Pelle-like kinase/interleukin-1 receptor-associated kinase: cross-talk between inflammatory signaling and insulin signaling that may contribute to insulin resistance. 1584 59

Nearly half of the U.S. adult population is overweight or obese, which may be related to increased energy intake combined with lack of physical activity. Obesity increases the risk of several chronic diseases including diabetes, coronary heart disease, hypertension, and stroke. Conjugated linoleic acids (CLA) were shown to decrease fat and increase lean mass in several animal studies. However, the effects of CLA in combination with exercise (Ex) on body composition have not been studied in an animal model. We examined the effect of a low concentration of either safflower oil as control (0.5%) or mixed isomers of CLA (0.4%) along with treadmill exercise on body composition in male Balb/C mice fed a high-fat diet (20% corn oil) in a 2 x 2 factorial design. CLA consumption lowered change in fat mass (P < 0.001) confirming the results of other studies, and change in fat mass decreased further (P < 0.001) with CLA and exercise. Change in lean mass did not increase with exercise alone; it increased, although not significantly, with CLA alone and increased significantly (P < 0.05) due to the combination of CLA and exercise. This effect was accompanied by decreased serum leptin levels and lower leptin mRNA expression in peritoneal fat (P < 0.001). Serum insulin, glucose, tumor necrosis factor (TNF)-alpha, and interleukin-6 were lower in CLA-fed mice than in controls (P < 0.05), whereas serum TNF-alpha was increased by exercise (P < 0.05). Exercise increased oxygen consumption and energy expenditure when measured under resting conditions (P < 0.05). In summary, the combination of dietary CLA and exercise decreased fat mass and increased lean mass in mice fed a high-fat diet, and these effects may be related in part to decreased serum leptin and exercise-induced increases in oxygen consumption and energy expenditure.
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PMID:The combination of dietary conjugated linoleic acid and treadmill exercise lowers gain in body fat mass and enhances lean body mass in high fat-fed male Balb/C mice. 1586 92


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