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Pal D, Dasgupta S, Kundu R, Maitra S, Das G, Mukhopadhyay S, Ray S, Majumdar SS, Bhattacharya S. Fetuin-A acts as an endogenous ligand of TLR4 to promote lipid-induced insulin resistance. Nat Med 2012; 18:1279-85. [PMID: 22842477 DOI: 10.1038/nm.2851] [Citation(s) in RCA: 655] [Impact Index Per Article: 54.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 05/31/2012] [Indexed: 02/06/2023]
Abstract
Toll-like receptor 4 (TLR4) has a key role in innate immunity by activating an inflammatory signaling pathway. Free fatty acids (FFAs) stimulate adipose tissue inflammation through the TLR4 pathway, resulting in insulin resistance. However, current evidence suggests that FFAs do not directly bind to TLR4, but an endogenous ligand for TLR4 remains to be identified. Here we show that fetuin-A (FetA) could be this endogenous ligand and that it has a crucial role in regulating insulin sensitivity via Tlr4 signaling in mice. FetA (officially known as Ahsg) knockdown in mice with insulin resistance caused by a high-fat diet (HFD) resulted in downregulation of Tlr4-mediated inflammatory signaling in adipose tissue, whereas selective administration of FetA induced inflammatory signaling and insulin resistance. FFA-induced proinflammatory cytokine expression in adipocytes occurred only in the presence of both FetA and Tlr4; removing either of them prevented FFA-induced insulin resistance. We further found that FetA, through its terminal galactoside moiety, directly binds the residues of Leu100-Gly123 and Thr493-Thr516 in Tlr4. FFAs did not produce insulin resistance in adipocytes with mutated Tlr4 or galactoside-cleaved FetA. Taken together, our results suggest that FetA fulfills the requirement of an endogenous ligand for TLR4 through which lipids induce insulin resistance. This may position FetA as a new therapeutic target for managing insulin resistance and type 2 diabetes.
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Affiliation(s)
- Durba Pal
- Cellular and Molecular Endocrinology Laboratory, Centre for Advanced Studies in Zoology, School of Life Science, Visva-Bharati (A Central University), Santiniketan, West Bengal, India
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202
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Abstract
Inflammation and lipid signaling are intertwined modulators of homeostasis and immunity. In addition to the extensively studied eicosanoids and inositol phospholipids, emerging studies indicate that many other lipid species act to positively and negatively regulate inflammatory responses. Conversely, inflammatory signaling can significantly alter lipid metabolism in the liver, adipose tissue, skeletal muscle, and macrophage in the context of infection, diabetes, and atherosclerosis. Here, we review recent findings related to this interconnected network from the perspective of immunity and metabolic disease.
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Affiliation(s)
- Christopher K Glass
- Department of Medicine, University of California, San Diego, La Jolla, CA 92093-0673, USA.
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203
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Lee ES, Park SH, Kim MS, Han SY, Kim HS, Kang YH. Caffeic acid disturbs monocyte adhesion onto cultured endothelial cells stimulated by adipokine resistin. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:2730-2739. [PMID: 22356100 DOI: 10.1021/jf203774y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Adipokines have been implicated in the pathogenesis of atherosclerosis via pro-inflammatory mechanisms contributing to insulin resistance. The adipokine resistin causes endothelium dysfunction, which plays an important role in sustaining atherogenesis. This study investigated whether resistin induced expression of cell adhesion molecules and integrins in endothelial cells and THP-1 monocytes and whether such induction was attenuated by 1-20 μM caffeic acid. Resistin enhanced endothelial expression of vascular cell adhesion molecule 1 (VCAM-1), intercellular cell adhesion molecule 1 (ICAM-1), and E-selectin and monocyte expression of β1, β2, and α4 integrins. The enhancement of these proteins was diminished by caffeic acid with reduced THP-1 cell adhesion on activated endothelium. Caffeic acid at ≤20 μM demoted resistin-stimulated interleukin 8 (IL-8) production responsible for ICAM-1 and β2 integrin induction. The endothelial up-regulation of IL-8 secretion by resistin entailed toll-like receptor 4 (TLR4) activation, but caffeic acid diminished IL-8 production and TLR4 induction. Furthermore, caffeic acid encumbered resistin-activated nuclear factor κB (NF-κB) signaling. These results demonstrate that caffeic acid blocked monocyte trafficking to resistin-activated endothelium via disturbing NF-κB signaling responsive to IL-8. Therefore, caffeic acid may have therapeutic potential in preventing obesity-associated atherosclerosis.
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Affiliation(s)
- Eun-Sook Lee
- Department of Food and Nutrition, Hallym University, Chuncheon, Kangwon-do, Korea
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204
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Stearoyl-CoA desaturase-1 (SCD1) augments saturated fatty acid-induced lipid accumulation and inhibits apoptosis in cardiac myocytes. PLoS One 2012; 7:e33283. [PMID: 22413010 PMCID: PMC3297642 DOI: 10.1371/journal.pone.0033283] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Accepted: 02/06/2012] [Indexed: 01/22/2023] Open
Abstract
Mismatch between the uptake and utilization of long-chain fatty acids in the myocardium leads to abnormally high intracellular fatty acid concentration, which ultimately induces myocardial dysfunction. Stearoyl-Coenzyme A desaturase-1 (SCD1) is a rate-limiting enzyme that converts saturated fatty acids (SFAs) to monounsaturated fatty acids. Previous studies have shown that SCD1-deficinent mice are protected from insulin resistance and diet-induced obesity; however, the role of SCD1 in the heart remains to be determined. We examined the expression of SCD1 in obese rat hearts induced by a sucrose-rich diet for 3 months. We also examined the effect of SCD1 on myocardial energy metabolism and apoptotic cell death in neonatal rat cardiac myocytes in the presence of SFAs. Here we showed that the expression of SCD1 increases 3.6-fold without measurable change in the expression of lipogenic genes in the heart of rats fed a high-sucrose diet. Forced SCD1 expression augmented palmitic acid-induced lipid accumulation, but attenuated excess fatty acid oxidation and restored reduced glucose oxidation. Of importance, SCD1 substantially inhibited SFA-induced caspase 3 activation, ceramide synthesis, diacylglycerol synthesis, apoptotic cell death, and mitochondrial reactive oxygen species (ROS) generation. Experiments using SCD1 siRNA confirmed these observations. Furthermore, we showed that exposure of cardiac myocytes to glucose and insulin induced SCD1 expression. Our results indicate that SCD1 is highly regulated by a metabolic syndrome component in the heart, and such induction of SCD1 serves to alleviate SFA-induced adverse fatty acid catabolism, and eventually to prevent SFAs-induced apoptosis.
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205
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Jungbauer A, Medjakovic S. Anti-inflammatory properties of culinary herbs and spices that ameliorate the effects of metabolic syndrome. Maturitas 2012; 71:227-39. [DOI: 10.1016/j.maturitas.2011.12.009] [Citation(s) in RCA: 83] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 12/09/2011] [Accepted: 12/10/2011] [Indexed: 01/07/2023]
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Abstract
Consumption of specific dietary fatty acids has been shown to influence risk and progression of several chronic diseases, such as cardiovascular disease, obesity, cancer, and arthritis. In recent years, insights into the mechanisms underlying the biological effects of fatty acids have improved considerably and have provided the foundation for the emerging concept of fatty acid sensing, which can be interpreted as the property of fatty acids to influence biological processes by serving as signaling molecules. An important mechanism of fatty acid sensing is via stimulation or inhibition of DNA transcription. Here, we focus on fatty acid sensing via regulation of gene transcription and address the role of peroxisome proliferator-activated receptors, sterol regulatory element binding protein 1, Toll-like receptor 4, G protein-coupled receptors, and other putative mediators.
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Affiliation(s)
- Anastasia Georgiadi
- Nutrition, Metabolism and Genomics Group, Wageningen University, Wageningen, the Netherlands
| | - Sander Kersten
- Nutrition, Metabolism and Genomics Group, Wageningen University, Wageningen, the Netherlands
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207
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Bilbo SD, Smith SH, Schwarz JM. A lifespan approach to neuroinflammatory and cognitive disorders: a critical role for glia. J Neuroimmune Pharmacol 2012; 7:24-41. [PMID: 21822589 PMCID: PMC3267003 DOI: 10.1007/s11481-011-9299-y] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 07/14/2011] [Indexed: 12/15/2022]
Abstract
Cognitive decline is a common problem of aging. Whereas multiple neural and glial mechanisms may account for these declines, microglial sensitization and/or dystrophy has emerged as a leading culprit in brain aging and dysfunction. However, glial activation is consistently observed in normal brain aging as well, independent of frank neuroinflammation or functional impairment. Such variability suggests the existence of additional vulnerability factors that can impact neuronal-glial interactions and thus overall brain and cognitive health. The goal of this review is to elucidate our working hypothesis that an individual's risk or resilience to neuroinflammatory disorders and poor cognitive aging may critically depend on their early life experience, which can change immune reactivity within the brain for the remainder of the lifespan. For instance, early-life infection in rats can profoundly disrupt memory function in young adulthood, as well as accelerate age-related cognitive decline, both of which are linked to enduring changes in glial function that occur in response to the initial infection. We discuss these findings within the context of the growing literature on the role of immune molecules and neuroimmune crosstalk in normal brain development. We highlight the intrinsic factors (e.g., chemokines, hormones) that regulate microglial development and their colonization of the embryonic and postnatal brain, and the capacity for disruption or "re-programming" of this crucial process by external events (e.g., stress, infection). An impact on glia, which in turn alters neural development, has the capacity to profoundly impact cognitive and mental health function at all stages of life.
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Affiliation(s)
- Staci D Bilbo
- Department of Psychology & Neuroscience, Duke University, Durham, NC 27708, USA.
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208
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Chemokine and free fatty acid levels in insulin-resistant state of successful pregnancy: a preliminary observation. Mediators Inflamm 2012; 2012:432575. [PMID: 22496600 PMCID: PMC3306909 DOI: 10.1155/2012/432575] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Revised: 10/31/2011] [Accepted: 11/10/2011] [Indexed: 01/12/2023] Open
Abstract
Increased insulin resistance and inflammatory action are observed in pregnancy-induced hypertension (PIH), but similar insulin resistance is observed also in successful pregnancy. To estimate insulin resistance and inflammatory activity in normal pregnancy and PIH, serum concentrations of free fatty acids (FFA; corrected with albumin to estimate unbound FFA), monocyte chemoattractant protein (MCP)-1, and high-molecular weight (HMW) adiponectin were measured in severe PIH patients with a BMI less than 25 kg/m2 and were measured 3 times during the course of pregnancy in women with normal pregnancies. FFA/albumin, MCP-1, and HMW adiponectin concentrations were significantly higher in PIH patients than in women with normal pregnancies. The 3 measurements of FFA/albumin showed a significant increase through the course of uncomplicated pregnancies. In contrast, MCP-1 and HMW adiponectin were significantly decreased during the course of pregnancy. These results suggest that the reduced MCP-1 concentration in normal pregnancy may be a pathway to inhibit the induction of pathological features from physiological insulin resistance and homeostatic inflammation.
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209
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Subcutaneous adipose tissue fatty acid desaturation in adults with and without rare adipose disorders. Lipids Health Dis 2012; 11:19. [PMID: 22300160 PMCID: PMC3286418 DOI: 10.1186/1476-511x-11-19] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 02/03/2012] [Indexed: 01/21/2023] Open
Abstract
Background Elevated stearoyl-CoA desaturase activity has been described in obese states, with an increased desaturation index (DI) suggesting enhanced lipogenesis. Differences in the DI among various phenotypes of abnormal adiposity have not been studied. Abnormal accumulation of subcutaneous adipose tissue occurs in rare adipose disorders (RADs) including Dercum's disease (DD), multiple symmetric lipomatosis (MSL), and familial multiple lipomatosis (FML). Examining the DI in subcutaneous fat of people with DD, MSL and FML may provide information on adipose tissue fatty acid metabolism in these disorders. The aims of this pilot study were: 1) to determine if differences in adipose tissue DIs are present among RADs, and 2) to determine if the DIs correlate to clinical or biochemical parameters. Methods Subcutaneous adipose tissue was obtained from human participants with DD (n = 6), MSL (n = 5), FML (n = 8) and obese Controls (n = 6). Fatty acid composition was determined by gas chromatography/mass spectrometry. The DIs (palmitoleic/palmitic, oleic/stearic, vaccenic/stearic ratios) were calculated from the gas chromatogram peak intensities. SCD1 gene expression was determined. Spearman's correlations between the DIs and available clinical or biochemical data were performed. Results In DD subjects, the vaccenic/stearic index was lower (p < 0.05) in comparison to Controls. Percent of total of the saturated fatty acid myristic acid was higher in DD compared with Controls and FML. Percent of monounsaturated vaccenic acid in DD trended lower when compared with Controls, and was decreased in comparison to FML. In MSL, total percent of the polyunsaturated fatty acids was significantly lower than in the Control group (p < 0.05). In the total cohort of subjects, the palmitoleic/palmitic and oleic/stearic DIs positively correlated with age, BMI, and percent body fat. Conclusions The positive associations between the DIs and measures of adiposity (BMI and percent body fat) support increased desaturase activity in obesity. The lower vaccenic/stearic DI in DD SAT compared with Controls suggests presence of other factors involved in fat accumulation in addition to lifestyle. Other mechanisms driving fat accumulation in DD such as inflammation or lymphatic dysfunction should be investigated.
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210
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Young JL, Mora A, Cerny A, Czech MP, Woda B, Kurt-Jones EA, Finberg RW, Corvera S. CD14 deficiency impacts glucose homeostasis in mice through altered adrenal tone. PLoS One 2012; 7:e29688. [PMID: 22253759 PMCID: PMC3258240 DOI: 10.1371/journal.pone.0029688] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2011] [Accepted: 12/03/2011] [Indexed: 01/22/2023] Open
Abstract
The toll-like receptors comprise one of the most conserved components of the innate immune system, signaling the presence of molecules of microbial origin. It has been proposed that signaling through TLR4, which requires CD14 to recognize bacterial lipopolysaccharide (LPS), may generate low-grade inflammation and thereby affect insulin sensitivity and glucose metabolism. To examine the long-term influence of partial innate immune signaling disruption on glucose homeostasis, we analyzed knockout mice deficient in CD14 backcrossed into the diabetes-prone C57BL6 background at 6 or 12 months of age. CD14-ko mice, fed either normal or high-fat diets, displayed significant glucose intolerance compared to wild type controls. They also displayed elevated norepinephrine urinary excretion and increased adrenal medullary volume, as well as an enhanced norepinephrine secretory response to insulin-induced hypoglycemia. These results point out a previously unappreciated crosstalk between innate immune- and sympathoadrenal- systems, which exerts a major long-term effect on glucose homeostasis.
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Affiliation(s)
- James L. Young
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Interdisciplinary Graduate Program, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Alfonso Mora
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Anna Cerny
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Michael P. Czech
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Bruce Woda
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Evelyn A. Kurt-Jones
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Robert W. Finberg
- Department of Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Silvia Corvera
- Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail:
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211
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Wang H, Zhao J, Huang Y, Yan X, Meyer AM, Du M, Vonnahme KA, Reynolds LP, Caton JS, Zhu MJ. Effects of maternal plane of nutrition and increased dietary selenium in first-parity ewes on inflammatory response in the ovine neonatal gut1. J Anim Sci 2012; 90:325-33. [DOI: 10.2527/jas.2011-4155] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- H. Wang
- Department of Animal Science, University of Wyoming, Laramie 82071
| | - J. Zhao
- Department of Animal Science, University of Wyoming, Laramie 82071
| | - Y. Huang
- Department of Animal Science, University of Wyoming, Laramie 82071
| | - X. Yan
- Department of Animal Science, University of Wyoming, Laramie 82071
| | - A. M. Meyer
- Department of Animal Science, North Dakota State University, Fargo 58108
| | - M. Du
- Department of Animal Science, University of Wyoming, Laramie 82071
| | - K. A. Vonnahme
- Department of Animal Science, North Dakota State University, Fargo 58108
| | - L. P. Reynolds
- Department of Animal Science, North Dakota State University, Fargo 58108
| | - J. S. Caton
- Department of Animal Science, North Dakota State University, Fargo 58108
| | - M. J. Zhu
- Department of Animal Science, University of Wyoming, Laramie 82071
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212
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Tishinsky JM, Dyck DJ, Robinson LE. Lifestyle factors increasing adiponectin synthesis and secretion. VITAMINS AND HORMONES 2012; 90:1-30. [PMID: 23017710 DOI: 10.1016/b978-0-12-398313-8.00001-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Adiponectin is an anti-inflammatory adipokine released from adipose tissue that is known to exert insulin-sensitizing effects in skeletal muscle and liver. Given that the secretion of adiponectin is impaired in obesity and related pathologies, strategies to enhance its synthesis and secretion are of interest. There is evidence that several lifestyle factors, including consumption of dietary long-chain n-3 PUFA, TZD administration, and weight loss can increase adiponectin synthesis and secretion. The effect of chronic exercise, independent of weight loss, is variable and less convincing. Potential mechanisms by which such lifestyle factors exert their favorable effects on adiponectin include activation of PPARγ and AMPK, regulation of posttranslational modifications, and changes in adipose tissue morphology and macrophage infiltration. As a clear role for adiponectin in mitigating obesity-related impairments in lipid metabolism and insulin sensitivity is evident, further research investigating factors that enhance adiponectin synthesis and secretion is distinctly warranted.
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Affiliation(s)
- Justine M Tishinsky
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, Ontario, Canada
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213
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Etiopathogenesis of nonalcoholic steatohepatitis: role of obesity, insulin resistance and mechanisms of hepatotoxicity. Int J Hepatol 2012; 2012:212865. [PMID: 22792473 PMCID: PMC3389710 DOI: 10.1155/2012/212865] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Revised: 02/26/2012] [Accepted: 04/25/2012] [Indexed: 12/14/2022] Open
Abstract
Incidence of nonalcoholic fatty liver disease is increasing with an estimated prevalence of 20-30% in developed nations. This is leading to increased incidence of chronic liver disease, cirrhosis, and hepatocellular cancer. It is critical to understand the etiology and pathogenesis of any disease to create therapeutic targets and develop new treatments. In this paper we discuss the etiology and pathogenesis of nonalcoholic steatohepatitis with special focus on obesity, role of insulin resistance, and molecular mechanisms of hepatotoxicity.
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214
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Trellakis S, Rydleuskaya A, Fischer C, Canbay A, Tagay S, Scherag A, Bruderek K, Schuler PJ, Brandau S. Low adiponectin, high levels of apoptosis and increased peripheral blood neutrophil activity in healthy obese subjects. Obes Facts 2012; 5:305-18. [PMID: 22722748 DOI: 10.1159/000339452] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 11/15/2011] [Indexed: 01/23/2023] Open
Abstract
OBJECTIVE Growing evidence supports a link between obesity and inflammation. Current research is focused on the role of adipokines such as adiponectin and immune cells, especially macrophages, in adipose tissue. Our aim was to examine the role of inflammation not in tissue but in the peripheral blood of healthy overweight and obese subjects. We especially investigated the role of neutrophils and their possible regulation by adiponectin. METHODS In healthy normal-weight, overweight, and obese human subjects (n = 32) the peripheral blood concentrations of adipokines, satiety hormones, apoptosis markers, and cytokines as well as the blood count were related to inflammation and neutrophils, at 3 independent days of examination. The response of neutrophils to stimulation by adiponectin was also investigated in vitro. RESULTS In obese and by tendency already in overweight subjects, inflammation was increased showing a higher neutrophil-to-lymphocyte ratio, elevated high-sensitivity C-reactive protein, increased chemokines (CXCL8, CCL3, CCL5), increased apoptosis markers (M30 and M65), and changes in hormone levels in the peripheral blood. LPS- and fMLP-induced production of CXCL8 by neutrophils was elevated in overweight and obese subjects. High plasma levels of adiponectin were associated with reduced CXCL8 production in peripheral blood neutrophils. In vitro, production of CXCL8 by neutrophils was inhibited by adiponectin. CONCLUSION Reduced adiponectin and enhanced apoptosis may occur already in the peripheral blood of healthy overweight subjects. This process seems to further enhance neutrophil activity in overweight and obese.
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Affiliation(s)
- Sokratis Trellakis
- Department of Otorhinolaryngology, Biometry and Epidemiology, University Hospital Essen, Essen, Germany.
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Regulation of LYRM1 gene expression by free fatty acids, adipokines, and rosiglitazone in 3T3-L1 adipocytes. EXPERIMENTAL DIABETES RESEARCH 2011; 2012:820989. [PMID: 22110480 PMCID: PMC3205718 DOI: 10.1155/2012/820989] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2011] [Revised: 08/13/2011] [Accepted: 08/18/2011] [Indexed: 11/24/2022]
Abstract
LYR motif containing 1 (LYRM1) is a novel gene that is abundantly expressed in the adipose tissue of obese subjects and is involved in insulin resistance. In this study, free fatty acids (FFAs) and tumor necrosis factor-α (TNF-α) are shown to upregulate LYRM1 mRNA expression in 3T3-L1 adipocytes. Conversely, resistin and rosiglitazone exert an inhibitory effect on LYRM1 mRNA expression. These results suggest that the expression of LYRM1 mRNA is affected by a variety of factors that are related to insulin sensitivity. LYRM1 may be an important mediator in the development of obesity-related insulin resistance.
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216
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A systems biology approach to nutritional immunology - focus on innate immunity. Mol Aspects Med 2011; 33:14-25. [PMID: 22061966 DOI: 10.1016/j.mam.2011.10.013] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2011] [Revised: 10/24/2011] [Accepted: 10/24/2011] [Indexed: 12/22/2022]
Abstract
Innate immunity and nutrient metabolism are complex biological systems that must work in concert to sustain and preserve life. The effector cells of the innate immune system rely on essential nutrients to generate energy, produce metabolic precursors for macromolecule biosynthesis and tune their responses to infectious agents. Thus disruptions to nutritional status have a substantial impact on immune competence and can result in increased susceptibility to infection in the case of nutrient deficiency, or chronic inflammation in the case of over-nutrition. The traditional, reductionist methods used in the study of nutritional immunology are incapable of exploring the extremely complex interactions between nutrient metabolism and innate immunity. Here, we review a relatively new analytical approach, systems biology, and highlight how it can be applied to nutritional immunology to provide a comprehensive view of the mechanisms behind nutritional regulation of the innate immune system.
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217
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Abstract
Type 2 diabetes mellitus is characterized by subclinical systemic inflammation and impaired regulation of blood glucose levels. Interestingly, impairment of glycemic control occurs despite substantial insulin secretion early in the course of this disease. Dysfunction of several organs (including pancreatic islets, liver, skeletal muscle, adipose tissue, gut, hypothalamus and the immune system) has been implicated in the pathogenesis of type 2 diabetes mellitus. However, diabetes-promoting lifestyle factors do not inevitably cause disease in all persons exposed. Hence, defense mechanisms must exist that can keep the detrimental influence of these risk factors at bay. Hormesis describes the phenomenon that exposure to a mild stressor confers resistance to subsequent, otherwise harmful, conditions of increased stress. This Review discusses the emerging concept that the effectiveness of an adaptive (hormetic) response to detrimental lifestyle factors determines the extent of protection from progression to type 2 diabetes mellitus. Further analysis of these protective hormetic responses at the molecular level should help to identify novel targets for preventive or therapeutic intervention in patients at risk of developing type 2 diabetes mellitus or those with overt disease.
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Affiliation(s)
- Hubert Kolb
- Immunobiology Research Group, Institute of Molecular Medicine, University of Düsseldorf, D-40001 Düsseldorf, Germany.
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218
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Goh FG, Midwood KS. Intrinsic danger: activation of Toll-like receptors in rheumatoid arthritis. Rheumatology (Oxford) 2011; 51:7-23. [PMID: 21984766 DOI: 10.1093/rheumatology/ker257] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
RA is a debilitating disorder that manifests as chronic localized synovial and systemic inflammation leading to progressive joint destruction. Recent advances in the molecular basis of RA highlight the role of both the innate and adaptive immune system in disease pathogenesis. Specifically, data obtained from in vivo animal models and ex vivo human tissue explants models has confirmed the central role of Toll-like receptors (TLRs) in RA. TLRs are pattern recognition receptors (PRRs) that constitute one of the primary host defence mechanisms against infectious and non-infectious insult. This receptor family is activated by pathogen-associated molecular patterns (PAMPs) and by damage-associated molecular patterns (DAMPs). DAMPs are host-encoded proteins released during tissue injury and cell death that activate TLRs during sterile inflammation. DAMPs are also proposed to drive aberrant stimulation of TLRs in the RA joint resulting in increased expression of cytokines, chemokines and proteases, perpetuating a vicious inflammatory cycle that constitutes the hallmark chronic inflammation of RA. In this review, we discuss the signalling mechanisms of TLRs, the central function of TLRs in the pathogenesis of RA, the role of endogenous danger signals in driving TLR activation within the context of RA and the current preclinical and clinical strategies available to date in therapeutic targeting of TLRs in RA.
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Affiliation(s)
- Fui G Goh
- Kennedy Institute of Rheumatology Division, Matrix Biology Department, Faculty of Medicine, Imperial College of Science, Technology and Medicine, 65 Aspenlea Road, Hammersmith, London W6 8LH, UK
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Miyazaki T, Kurokawa J, Arai S. AIMing at metabolic syndrome. -Towards the development of novel therapies for metabolic diseases via apoptosis inhibitor of macrophage (AIM).-. Circ J 2011; 75:2522-31. [PMID: 21970839 DOI: 10.1253/circj.cj-11-0891] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Metabolic syndrome (MetS) is a cascade of metabolic diseases, starting with obesity and progressing to atherosclerosis, and is often fatal because of serious cardiovascular problems such as heart/brain infarction and hemorrhage. Accumulating evidence has revealed a critical involvement of inflammatory responses triggered by lesional macrophages in the pathogenesis of MetS. Importantly, we found that macrophages are associated with disease progression, not only in the induction of inflammation but also in the production of apoptosis inhibitor of macrophages (AIM), which we initially identified as a soluble factor expressed by macrophages. In atherosclerotic plaques, AIM is highly expressed by foam macrophages and inhibits apoptosis of these cells, which results in the accumulation of macrophages, causing inflammatory responses within the lesion, and ultimately disease progression. In adipose tissue, macrophage-derived AIM is incorporated into adipocytes through CD36-mediated endocytosis, thereby reducing the activity of cytosolic fatty acid synthase. This unique response stimulates lipolysis, resulting in a decrease in adipocyte size, which is physiologically relevant to the prevention of obesity. The lipolytic response also stimulates inflammation of adipocytes in association with the induction of metabolic disorders subsequent to obesity. Thus, AIM is involved in the progression of MetS in both an advancing and inhibitory fashion. Regulation of AIM could therefore be therapeutically applicable for MetS.
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Affiliation(s)
- Toru Miyazaki
- Laboratory of Molecular Biomedicine for Pathogenesis, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, The University of Tokyo, Tokyo, Japan.
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Ros Pérez M, Medina-Gómez G. [Obesity, adipogenesis and insulin resistance]. ACTA ACUST UNITED AC 2011; 58:360-9. [PMID: 21778123 DOI: 10.1016/j.endonu.2011.05.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Revised: 04/12/2011] [Accepted: 05/11/2011] [Indexed: 12/25/2022]
Abstract
Insulin resistance precedes the development of type 2 diabetes mellitus and is also a common denominator in the so-called metabolic syndrome. Although the cause of insulin resistance has not been fully elucidated, it seems clear that lifestyle changes, including little physical exercise and constant access to food, particularly in developed and economically emergent countries, as well as genetic factors, appear to have triggered the escalating incidence of diseases related to insulin resistance, including type 2 diabetes and metabolic syndrome. Obesity is considered as a risk factor for developing insulin resistance. Increased adipose tissue has been related to an increased production of pro-inflammatory cytokines which, together with fatty acids, appear to be responsible for the development of insulin resistance. Thus, a greater or lesser expansibility or ability of adipose tissue to store lipids also appears to play a significant role in the development of insulin resistance because overcoming of this capacity, which is variable in each case, would result in leaking of lipids to other tissues where they could interfere with insulin signaling. This article reviews various molecular mechanisms related to the development of insulin resistance and its relationship to expansibility of adipose tissue and obesity.
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Affiliation(s)
- Manuel Ros Pérez
- Departamento de Bioquímica, Fisiología y Genética Molecular, Universidad Rey Juan Carlos, Facultad de Ciencias de la Salud, Alcorcón, Madrid, España
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Apoptosis inhibitor of macrophage (AIM) is required for obesity-associated recruitment of inflammatory macrophages into adipose tissue. Proc Natl Acad Sci U S A 2011; 108:12072-7. [PMID: 21730133 DOI: 10.1073/pnas.1101841108] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Infiltration of inflammatory macrophages into adipose tissues with the progression of obesity triggers insulin resistance and obesity-related metabolic diseases. We recently reported that macrophage-derived apoptosis inhibitor of macrophage (AIM) protein is increased in blood in line with obesity progression and is incorporated into adipocytes, thereby inducing lipolysis in adipose tissue. Here we show that such a response is required for the recruitment of adipose tissue macrophages. In vitro, AIM-dependent lipolysis induced an efflux of palmitic and stearic acids from 3T3-L1 adipocytes, thereby stimulating chemokine production in adipocytes via activation of toll-like receptor 4 (TLR4). In vivo administration of recombinant AIM to TLR4-deficient (TLR4(-/-)) mice resulted in induction of lipolysis without chemokine production in adipose tissues. Consistently, mRNA levels for the chemokines that affect macrophages were far lower in AIM-deficient (AIM(-/-)) than in wild-type (AIM(+/+)) obese adipose tissue. This reduction in chemokine production resulted in a marked prevention of inflammatory macrophage infiltration into adipose tissue in obese AIM(-/-) mice, although these mice showed more advanced obesity than AIM(+/+) mice on a high-fat diet. Diminished macrophage infiltration resulted in decreased inflammation locally and systemically in obese AIM(-/-) mice, thereby protecting them from insulin resistance and glucose intolerance. These results indicate that the increase in blood AIM is a critical event for the initiation of macrophage recruitment into adipose tissue, which is followed by insulin resistance. Thus, AIM suppression might be therapeutically applicable for the prevention of obesity-related metabolic disorders.
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Hsueh HW, Zhou Z, Whelan J, Allen KGD, Moustaid-Moussa N, Kim H, Claycombe KJ. Stearidonic and eicosapentaenoic acids inhibit interleukin-6 expression in ob/ob mouse adipose stem cells via Toll-like receptor-2-mediated pathways. J Nutr 2011; 141:1260-6. [PMID: 21562237 DOI: 10.3945/jn.110.132571] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Increased adipose tissue positively correlates with circulating inflammatory cytokines such as IL-6. We previously reported that adipose stem cells from genetically obese ob/ob mice produce significantly higher levels of IL-6 compared with other cell types such as adipocytes and macrophages within adipose tissue. We also demonstrated that (n-3) PUFA have antiinflammatory effects on adipocyte IL-6 secretion. Based on these findings, we hypothesized that EPA [20:5 (n-3)] and stearidonic acid [SDA, 18:4 (n-3)] would decrease LPS (200 μg/L)-induced IL-6 secretion and IL-6 mRNA content in the adipose stem cells. SDA (100 μmol/L) and EPA (100 μmol/L) significantly reduced LPS-induced IL-6 secretion and decreased IL-6 mRNA expression. To determine the underlying intracellular mechanisms, we tested whether LPS-induced Toll-like-receptor (TLR) 4 and TLR2 expression were modulated by these fatty acids using Western-blot analysis. EPA and SDA suppressed LPS-induced TLR2 but not TLR4 protein expression in the adipose stem cells. Furthermore, SDA and EPA significantly lowered the activation and translocation of NF-κB, a TLR2 downstream signaling target, while protein expression of extracellular signal-regulated kinases-1/2 were unaffected. Collectively, our results suggest that EPA and SDA inhibit LPS-induced IL-6 secretion and IL-6 mRNA expression in the adipose stem cells by decreasing TRL2-mediated signaling pathways.
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Affiliation(s)
- Hui Wen Hsueh
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI 48824, USA
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Abstract
Obesity is a highly prevalent health problem in Western countries that leads to many important diseases such as type 2 diabetes and metabolic syndrome being now considered an inflammatory chronic disease. Adipocytes are no longer considered passive cells storing fat since they are major producers of inflammatory cytokines during obesity. Adipocytes and macrophages share many biological properties including the synthesis of similar molecules regulating inflammation. Fatty acid levels are elevated in obesity and induce inflammatory pathways by yet a mostly unknown mechanism, leading to the development of insulin and leptin resistance. Recent studies suggest that these effects could be mediated through the activation of toll-like receptors (TLR). TLR signalling pathways might contribute to the development of obesity-associated insulin resistance, thus representing a connection between innate immunity and metabolism. Here, we summarize the recent evidence for the important role that TLRs play in adipose tissue, obesity and insulin resistance.
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Affiliation(s)
- Manuel Fresno
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
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Choudhury M, Jonscher KR, Friedman JE. Reduced mitochondrial function in obesity-associated fatty liver: SIRT3 takes on the fat. Aging (Albany NY) 2011; 3:175-8. [PMID: 21386135 PMCID: PMC3082013 DOI: 10.18632/aging.100289] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Aging is associated with various metabolic disorders that may have their origin in the liver, including non-alcoholic fatty liver disease, obesity, type 2 diabetes mellitus, and atherosclerosis. Although well-characterized in models of caloric restriction, relatively little is known about the role of sirtuins and acetylation under conditions of caloric excess. Sirtuins are NAD (+)-dependent protein deacetylases that mediate adaptive responses to a variety of stresses, including calorie restriction and metabolic stress. Sirtuin 3 (SIRT3) is localized within the mitochondrial matrix, where it regulates acetylation levels of a diverse set of metabolic enzymes. When normal mice are fed a high fat diet they demonstrate reduced SIRT3 activity, impaired mitochondrial function, and hyperacetylation of a diverse set of proteins in their livers. Furthermore, SIRT3 knockout mice have signs of accelerated aging and cancer. Understanding SIRT3?s biochemical function and regulation in the liver under conditions of caloric excess may potentially increase our understanding of the normal aging process and diseases associated with aging, such as diabetes, fatty liver disease, or cancer.
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Affiliation(s)
- Mahua Choudhury
- Department of Pediatrics, University of Colorado School of Medicine, Aurora, CO 80045, USA
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225
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Negative regulation of dermal fibroblasts by enlarged adipocytes through release of free fatty acids. J Invest Dermatol 2011; 131:2004-9. [PMID: 21697886 DOI: 10.1038/jid.2011.145] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Subcutaneous adipose tissue lies just beneath the dermal layer, but the interaction between the two types of tissue remains obscure. Recently, we reported that obesity is associated with decreased dermal elasticity. To investigate the mechanism of the adipose tissue/dermal interaction, fibroblasts were cocultured with small or enlarged adipocytes, using a membrane insert to prevent direct contact. Enlarged adipocytes reduced 3T3-L1 fibroblast proliferation and gene expression of collagen (I)-α1 (col (I)-α1) and elastin while increasing gene expression of matrix metalloproteinase 13 (MMP13). In contrast, small adipocytes had no such effects. These results indicate that factors secreted by enlarged adipocytes influence dermal condition. As enlarged adipocytes are known to release free fatty acids (FFAs), the effects of these acids on 3T3-L1 fibroblasts were examined. Palmitic acid decreased fibroblast proliferation, reduced gene expressions of col (I)-α1 and elastin, and increased MMP13. Similar effects were observed in human dermal fibroblasts. The influence of palmitic acid on fibroblasts was inhibited by eicosapentaenoic acid (EPA), an inhibitor of Toll-like receptors (TLRs). Furthermore, EPA inhibited the effects of enlarged adipocytes on fibroblasts in the coculture system. These data indicate that enlarged adipocytes negatively control the function of dermal fibroblasts through the activation of TLRs by secreted FFAs.
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226
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Ibrahim A, Mbodji K, Hassan A, Aziz M, Boukhettala N, Coëffier M, Savoye G, Déchelotte P, Marion-Letellier R. Anti-inflammatory and anti-angiogenic effect of long chain n-3 polyunsaturated fatty acids in intestinal microvascular endothelium. Clin Nutr 2011; 30:678-87. [PMID: 21632157 DOI: 10.1016/j.clnu.2011.05.002] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Revised: 04/22/2011] [Accepted: 05/02/2011] [Indexed: 12/11/2022]
Abstract
BACKGROUND & AIMS The role of endothelial cells in inflammatory bowel disease has been recently emphasized. Endothelial activation and expression of adhesion molecules are critical for leukocytes recruitment into the inflammatory wall. Compelling evidence demonstrated anti-inflammatory effects of long chain n-3 PUFA in inflammatory models. We previously showed that long chain n-3 PUFA (EPA and DHA) inhibited inflammatory response in epithelial and dendritic cells. As long chain n-3 PUFA treatment led to a decreased expression of adhesion molecules in endothelial cells from other organs, we have now investigated their effect on intestinal endothelial cells in vitro and in colitic rats. METHODS In vitro study: Primary culture of human intestinal microvascular endothelial cells (HIMEC) were pre-treated with DHA and then incubated with IL-1β. In vivo study: Colitis was induced in 2 groups at day0 by intrarectal injection of 2-4-6-trinitrobenzen sulfonic acid (TNBS). Rats received by gavage either fish oil, rich in EPA and DHA (TNBS+n-3) or an isocaloric isolipidic oil formula for 14 days. RESULTS DHA led to a decreased VCAM-1, TLR4, cyclooxygenase-2 and VEGFR2 expression and a decreased production of IL-6, IL-8 and GM-CSF and a reduced production of PGE(2) and LTB(4) (p < 0.001) in IL-1β-induced HIMEC. Similarly, dietary intervention with fish oil rich in EPA and DHA significantly decreased colon production of PGE(2) and LTB(4,) endothelial VCAM-1 and VEGFR2 in rats with colitis. CONCLUSIONS Data obtained from in vitro and in vivo studies reveal a potential anti-angiogenic role of long chain n-3 PUFA in intestinal endothelial cells. This protective effect of long chain n-3 PUFA may partly explain the observed benefit of dietary intake of long chain n-3 PUFA in IBD development.
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Affiliation(s)
- Ayman Ibrahim
- Appareil Digestif Environnement Nutrition (ADEN EA 4311), Medicine, University of Rouen, I.F.R. 23, Institute of Biomedical Research, 22 boulevard Gambetta, 76183 Rouen cedex, France
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Dalmas E, Clément K, Guerre-Millo M. Defining macrophage phenotype and function in adipose tissue. Trends Immunol 2011; 32:307-14. [PMID: 21616718 DOI: 10.1016/j.it.2011.04.008] [Citation(s) in RCA: 169] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2011] [Revised: 03/18/2011] [Accepted: 04/21/2011] [Indexed: 12/12/2022]
Abstract
In obesity, chronic low-grade inflammation is thought to mediate the effects of increased adipose tissue mass on metabolic comorbidity. Of the different cell types that contribute to obesity-induced inflammation in adipose tissue, this review focuses on macrophages and their monocytes precursors. Mechanisms for monocyte recruitment to adipose tissue, and how both monocytes and macrophages are phenotypically modified in this environment in response to increasing fat mass, are considered. The versatile phenotype of adipose tissue macrophages might contribute not only to inflammatory and metabolic alterations, but could also help to maintain adipose tissue homeostasis in the setting of obesity.
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228
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Youssef-Elabd EM, McGee KC, Tripathi G, Aldaghri N, Abdalla MS, Sharada HM, Ashour E, Amin AI, Ceriello A, O'Hare JP, Kumar S, McTernan PG, Harte AL. Acute and chronic saturated fatty acid treatment as a key instigator of the TLR-mediated inflammatory response in human adipose tissue, in vitro. J Nutr Biochem 2011; 23:39-50. [PMID: 21414768 PMCID: PMC3243902 DOI: 10.1016/j.jnutbio.2010.11.003] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 10/14/2010] [Accepted: 11/18/2010] [Indexed: 01/28/2023]
Abstract
A post-prandial increase in saturated fatty acids (SFAs) and glucose (Glc) activates an inflammatory response, which may be prolonged following restoration of physiological SFAs and Glc levels--a finding referred to as 'metabolic memory'. This study examined chronic and oscillating SFAs and Glc on the inflammatory signalling pathway in human adipose tissue (AT) and adipocytes (Ads) and determined whether Ads are subject to "metabolic memory." Abdominal (Abd) subcutaneous (Sc) explants and Ads were treated with chronic low glucose (L-Glc): 5.6 mM and high glucose (H-Glc): 17.5 mM, with low (0.2 mM) and high (2 mM) SFA for 48 h. Abd Sc explants and Ads were also exposed to the aforementioned treatment regimen for 12-h periods, with alternating rest periods of 12 h in L-Glc. Chronic treatment with L-Glc and high SFAs, H-Glc and high SFAs up-regulated key factors of the nuclear factor-κB (NFκB) pathway in Abd Sc AT and Ads (TLR4, NFκB; P<.05), whilst down-regulating MyD88. Oscillating Glc and SFA concentrations increased TLR4, NFκB, IKKβ (P<.05) in explants and Ads and up-regulated MyD88 expression (P<.05). Both tumor necrosis factor α and interleukin 6 (P<.05) secretion were markedly increased in chronically treated Abd Sc explants and Ads whilst, with oscillating treatments, a sustained inflammatory effect was noted in absence of treatment. Therefore, SFAs may act as key instigators of the inflammatory response in human AT via NFκB activation, which suggests that short-term exposure of cells to uncontrolled levels of SFAs and Glc leads to a longer-term inflammatory insult within the Ad, which may have important implications for patients with obesity and Type 2 diabetes.
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229
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Vijay-Kumar M, Aitken JD, Carvalho FA, Ziegler TR, Gewirtz AT, Ganji V. Loss of function mutation in toll-like receptor-4 does not offer protection against obesity and insulin resistance induced by a diet high in trans fat in mice. JOURNAL OF INFLAMMATION-LONDON 2011; 8:2. [PMID: 21314942 PMCID: PMC3048481 DOI: 10.1186/1476-9255-8-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 02/11/2011] [Indexed: 02/06/2023]
Abstract
Background Toll-like receptor-4 (TLR4) triggers inflammatory signaling in response to microbial lipoploysaccharide. It has been reported that loss of TLR4 protected against saturated fat-induced inflammation and insulin resistance. It is not known whether loss of TLR4 function offers protection against trans fat (TF) induced obesity, inflammation, and insulin resistance. We investigated whether mice with loss of function mutation in TLR4 were resistant to TF-induced pathologies such as obesity, inflammation, hyperglycemia, and hyperinsulinemia. Methods C57BL/6j and C57BL/10 mice were cross bred to generate TLR4 mutant and wild type (WT). TLR4 mutant (n = 12) and WT (n = 12) mice were fed either low fat (LF) (13.5% fat energy) or high TF diets (60% fat energy) for 12 weeks. In vitro experiments were conducted on mouse macrophage cells (RAW 264.7 and J774A.1) to investigate whether elaidic (trans 18:1) or oleic acid (cis 18:1) would upregulate inflammatory markers. Results TLR4 mutant mice were ~26.4% heavier than WT mice. In both genotypes, mice that received TF diet were significantly heavier than those mice that received LF diet (P < 0.01). TLR4 mutant mice compared to WT mice had significantly higher fasting blood glucose, serum insulin, insulin resistance, serum leptin, and serum cholesterol when they received TF diet (P < 0.05). No upregulation of iNOS or COX2 in response to either elaidic or oleic acid in macrophage cells was observed. Conclusions Loss of function mutation in TLR4 not only did not protect mice from TF-induced obesity, hyperglycemia, hyperinsulinemia, and hypercholesterolemia but also exacerbated the above pathologies suggesting that functional TLR4 is necessary in attenuating TF-induced deleterious effects. It is likely that TF induces pathologies through pathways independent of TLR4.
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Affiliation(s)
- Matam Vijay-Kumar
- Division of Nutrition, School of Health Professions, College of Health and Human Sciences, Georgia State University, Atlanta, GA 30302, USA.
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Role of toll-like receptors and their downstream molecules in the development of nonalcoholic Fatty liver disease. Gastroenterol Res Pract 2011; 2010:362847. [PMID: 21274430 PMCID: PMC3026974 DOI: 10.1155/2010/362847] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2010] [Revised: 10/28/2010] [Accepted: 12/15/2010] [Indexed: 02/07/2023] Open
Abstract
Activation of innate immunity is associated with the development of liver disease, including non-alcoholic fatty liver disease (NAFLD). In the innate immune system, Toll-like receptors (TLRs) are sensors that recognize bacterial and viral components such as lipopolysaccharide, bacterial DNA, and peptidoglycan. Recent data have demonstrated that the liver is exposed to a high load of TLR ligands due to bacterial overgrowth and increased intestinal permeability in NAFLD. Upon stimulation by these TLR ligands, hepatic immune cells produce various mediators that are involved in host defense. On the other hand, these mediators alter lipid metabolism, insulin signaling, and cell survival. Indeed, some TLR-deficient mice demonstrate lesser degrees of NAFLD even though TLR ligands are increased. This paper will highlight the recent progress on the study of TLR signaling and their downstream molecules in the development of NAFLD.
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231
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Interactions of overweight, poor oral health, and stress related to chronic disease in an aging population. Curr Gerontol Geriatr Res 2011; 2010:614814. [PMID: 21197087 PMCID: PMC3004404 DOI: 10.1155/2010/614814] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2010] [Revised: 09/09/2010] [Accepted: 10/24/2010] [Indexed: 11/30/2022] Open
Abstract
The prevalence of excess body mass (XBM), poor oral health (POH), and stress in a secluded population of aged (≥60 years) Hmong immigrants was surveyed. The findings were related to the prevalence of diabetes in the same population. Diabetes was associated separately with POH (OR 2.4; CL 1.3, 4.2) or with XBM (OR 2.5; CL 1.4, 4.8). The association of diabetes with the combination of XBM and POH was striking (OR 5.1; CL 3.4, 7.5); that apparent synergism has not been fully appreciated. We describe a mechanism that explains the synergism. The concept of “thrifty genotype” is a plausible explanation of XBM in the elderly Hmong immigrants and possibly the current older Laotian population. POH is common among elderly Laotians as it is in most developing countries. We conclude that synergism of XBM and POH significantly elevates the prevalence of diabetes among aging populations and probably other age groups as well.
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232
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Könner AC, Brüning JC. Toll-like receptors: linking inflammation to metabolism. Trends Endocrinol Metab 2011; 22:16-23. [PMID: 20888253 DOI: 10.1016/j.tem.2010.08.007] [Citation(s) in RCA: 245] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 08/25/2010] [Accepted: 08/25/2010] [Indexed: 02/06/2023]
Abstract
Obesity has been characterized as a state of chronic inflammation. Inflammatory signaling not only causes peripheral insulin resistance, but also promotes neuronal insulin and leptin resistance, which further propagates a positive energy balance. Upon development of obesity, numerous conditions, including increased circulating cytokine concentrations and cell autonomous dysregulation of homeostatic signaling pathways, such as the endoplasmic reticulum stress response, promote activation of stress kinases, to cause peripheral insulin as well as central insulin and leptin resistance. Recently, activation of toll-like receptor (TLR) signaling has been recognized as an alternative activator of obesity-induced inflammation. In this paper, we review recent progress in defining the molecular basis of obesity-associated TLR activation and its role in the development of metabolic syndrome.
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Affiliation(s)
- A Christine Könner
- Department of Mouse Genetics and Metabolism, Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), Center of Molecular Medicine Cologne (CMMC), University of Cologne and Max Planck Institute for the Biology of Ageing, D-50674 Cologne, Germany
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233
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Bauer S, Wanninger J, Schmidhofer S, Weigert J, Neumeier M, Dorn C, Hellerbrand C, Zimara N, Schäffler A, Aslanidis C, Buechler C. Sterol regulatory element-binding protein 2 (SREBP2) activation after excess triglyceride storage induces chemerin in hypertrophic adipocytes. Endocrinology 2011; 152:26-35. [PMID: 21084441 DOI: 10.1210/en.2010-1157] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Chemerin is an adipokine whose systemic concentration and adipose tissue expression is increased in obesity. Chemerin is highly abundant in adipocytes, yet the molecular mechanisms mediating its further induction in obesity have not been clarified. Adipocyte hypertrophy contributes to dysregulated adipokine synthesis, and we hypothesized that excess loading with free fatty acids (FFA) stimulates chemerin synthesis. Chemerin was expressed in mature adipocytes, and differentiation of 3T3-L1 cells in the presence of FFA further increased its level. TNF and IL-6 were induced by FFA, but concentrations were too low to up-regulate chemerin. Sterol regulatory element-binding protein 2 (SREBP2) was activated in these cells, indicative for cholesterol shortage. Suppression of cholesterol synthesis by lovastatin led to activation of SREBP2 and increased chemerin, and supplementation with mevalonate reversed this effect. Knockdown of SREBP2 reduced basal and FFA-induced chemerin. EMSA confirmed binding of 3T3-L1 adipocyte nuclear proteins to a SREBP site in the chemerin promotor. SREBP2 was activated and chemerin was induced in adipose tissue of mice fed a high-fat diet, and higher systemic levels seem to be derived from adipocytes. Lipopolysaccharide-mediated elevation of chemerin was similarly effective as induction by FFA, indicating that both mechanisms are equally important. Chemokine-like receptor 1 was not altered by the incubations mentioned above, and higher expression in fat of mice fed a high-fat diet may reflect increased number of adipose tissue-resident macrophages in obesity. In conclusion, the current data show that adipocyte hypertrophy and chronic inflammation are equally important in inducing chemerin synthesis.
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Affiliation(s)
- Sabrina Bauer
- Department of Internal Medicine I, Regensburg University Hospital, D-93042 Regensburg, Germany.
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234
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Hosek J, Zavalova V, Kollar P. Effect of solvent on cytotoxicity and bioavailability of fatty acids. Immunopharmacol Immunotoxicol 2010; 32:462-5. [PMID: 20095809 DOI: 10.3109/08923970903513147] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Fatty acids (FAs) represent an important part of cell membranes and a source of energy. However, their abundance is linked with several diseases such as type 2 diabetes mellitus, and for this reason they are studied intensively. In this article we compare the two main methods of dissolving FAs for work in vitro, (i) dissolution in dimethylsulfoxide (DMSO) and (ii) conjugation with bovine serum albumin (BSA), and describe the effects of the solvent on cytotoxicity (determination of viability) and bioavailability (as shown by the impact on the gene expression of TNF-alpha). We have found that conjugation with BSA is significantly less cytotoxic than dissolution in DMSO and also yields greater bioavailability.
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Affiliation(s)
- Jan Hosek
- Department of Natural Drugs, Faculty of Pharmacy, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Czech Republic.
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235
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Noguchi T, Sado T, Naruse K, Shigetomi H, Onogi A, Haruta S, Kawaguchi R, Nagai A, Tanase Y, Yoshida S, Kitanaka T, Oi H, Kobayashi H. Evidence for activation of Toll-like receptor and receptor for advanced glycation end products in preterm birth. Mediators Inflamm 2010; 2010:490406. [PMID: 21127710 PMCID: PMC2993025 DOI: 10.1155/2010/490406] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Revised: 10/11/2010] [Accepted: 10/26/2010] [Indexed: 12/22/2022] Open
Abstract
OBJECTIVE Individuals with inflammation have a myriad of pregnancy aberrations including increasing their preterm birth risk. Toll-like receptors (TLRs) and receptor for advanced glycation end products (RAGE) and their ligands were all found to play a key role in inflammation. In the present study, we reviewed TLR and RAGE expression, their ligands, and signaling in preterm birth. RESEARCH DESIGN AND METHODS A systematic search was performed in the electronic databases PubMed and ScienceDirect up to July 2010, combining the keywords "preterm birth," "TLR", "RAGE", "danger signal", "alarmin", "genomewide," "microarray," and "proteomics" with specific expression profiles of genes and proteins. RESULTS This paper provides data on TLR and RAGE levels and critical downstream signaling events including NF-kappaB-dependent proinflammatory cytokine expression in preterm birth. About half of the genes and proteins specifically present in preterm birth have the properties of endogenous ligands "alarmin" for receptor activation. The interactions between the TLR-mediated acute inflammation and RAGE-mediated chronic inflammation have clear implications for preterm birth via the TLR and RAGE system, which may be acting collectively. CONCLUSIONS TLR and RAGE expression and their ligands, signaling, and functional activation are increased in preterm birth and may contribute to the proinflammatory state.
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Affiliation(s)
- Taketoshi Noguchi
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
| | - Toshiyuki Sado
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
| | - Katsuhiko Naruse
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
| | - Hiroshi Shigetomi
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
| | - Akira Onogi
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
| | - Shoji Haruta
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
| | - Ryuji Kawaguchi
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
| | - Akira Nagai
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
| | - Yasuhito Tanase
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
| | - Shozo Yoshida
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
| | - Takashi Kitanaka
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
| | - Hidekazu Oi
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
| | - Hiroshi Kobayashi
- Department of Obstetrics and Gynecology, Nara Medical University, 840 Shijo-cho, Kashihara, Nara 634-8522, Japan
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Kopp A, Bala M, Buechler C, Falk W, Gross P, Neumeier M, Schölmerich J, Schäffler A. C1q/TNF-related protein-3 represents a novel and endogenous lipopolysaccharide antagonist of the adipose tissue. Endocrinology 2010; 151:5267-78. [PMID: 20739398 DOI: 10.1210/en.2010-0571] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Proteins secreted by adipocytes (adipokines) play an important role in the pathophysiology of type 2 diabetes mellitus and the associated chronic and low-grade state of inflammation. It was the aim to characterize the antiinflammatory potential of the new adipocytokine, C1q/TNF-related protein-3 (CTRP-3), which shows structural homologies to the pleiotropic adipocytokine adiponectin. mRNA and protein expression of CTRP-3 was analyzed by RT-PCR and Western blot. Recombinant CTRP-3 and small interfering RNA-based strategies were used to investigate the effect of CTRP-3 on toll-like receptor (TLR) ligand, lipopolysaccharide (LPS)-, and lauric acid-induced chemokine release of monocytes and adipocytes. Together with complex ELISA-based techniques, a designed TLR4/myeloid differentiation protein-2 fusion molecule shown to bind LPS was used to prove the ability of CTRP-3 to act as endogenous LPS antagonist. CTRP-3 is synthesized in monocytes and adipocytes. The recombinant protein dose-dependently inhibits the release of chemokines in monocytes and adipocytes that were induced by lauric acid, LPS, and other TLR ligands in vitro and ex vivo. CTRP-3 inhibits monocyte chemoattractant protein-1 release in adipocytes, whereas small interfering RNA-mediated knockdown of CTRP-3 up-regulates monocyte chemoattractant protein-1 release, reduces lipid droplet size, and decreases intracellular triglyceride concentration in adipocytes, causing a dedifferentiation into a more proinflammatory and immature phenotype. By using a designed TLR4/MD-2 fusion molecule, it is shown by different techniques that CTRP-3 specifically and effectively inhibits the binding of LPS to its receptor, TLR4/MD-2. CTRP-3 inhibits three basic and common proinflammatory pathways involved in obesity and type 2 diabetes mellitus (adipo-inflammation) by acting as an endogenous LPS antagonist of the adipose tissue.
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Affiliation(s)
- Andrea Kopp
- Department of Internal Medicine I, University of Regensburg, D-93042 Regensburg, Germany
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Li F, Wang CH, Wang JG, Thai T, Boysen G, Xu L, Turner AL, Wolberg AS, Mackman N, Maeda N, Takahashi N. Elevated tissue factor expression contributes to exacerbated diabetic nephropathy in mice lacking eNOS fed a high fat diet. J Thromb Haemost 2010; 8:2122-32. [PMID: 20626618 PMCID: PMC5744483 DOI: 10.1111/j.1538-7836.2010.03976.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Human eNOS (NOS3) polymorphisms that lower its expression are associated with advanced diabetic nephropathy (DN), and the lack of eNOS accelerates DN in diabetic mice. Diabetes is associated with fibrin deposition. Lack of nitric oxide and fatty acids stimulates the NF-kB pathway, which increases tissue factor (TF). OBJECTIVES To test the hypothesis that TF contributes to the severity of DN in the diabetic eNOS(-/-) mice fed a high-fat diet (HF). METHODS We made eNOS(-/-) and wild-type mice diabetic with streptozotocin. Half of them were placed on HF. RESULTS Blood glucose levels were not affected by either the diet or eNOS genotype. Lack of eNOS in the diabetic mice increased urinary albumin excretion, glomerulosclerosis, interstitial fibrosis, and glomerular basement membrane thickness. HF by itself did not affect DN in the wild-type mice, but significantly enhanced DN in eNOS(-/-) mice. More than half of diabetic eNOS(-/-) mice on HF died prematurely with signs of thrombotic complications. Diabetic kidneys contained fibrin and TF, and their levels were increased by the lack of eNOS and by HF in an additive fashion. The HF diet increased the kidney expression of inflammatory genes. The increase in TF preceded DN, and administration of an anti-mouse TF antibody to diabetic mice reduced the expression of inflammatory genes. CONCLUSION Together, these data indicate a causal link between TF and the exacerbation of DN in eNOS(-/-) mice. The condition is significantly worsened by enhanced inflammatory responses to an HF diet via TF.
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Affiliation(s)
- Feng Li
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Chih-Hong Wang
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Jian-Guo Wang
- Department of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Tiffany Thai
- Department of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Gunnar Boysen
- Center of Environmental Health and Susceptibility, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Longquan Xu
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Adam L Turner
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Alisa S. Wolberg
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Nigel Mackman
- Department of Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Nobuyo Maeda
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
| | - Nobuyuki Takahashi
- Department of Pathology and Laboratory Medicine, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
- Department of Cell and Molecular Physiology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7525, USA
- Tohoku University, Graduate Schools of Pharmaceutical Sciences and Medicine, Sendai, 980-8578, Japan
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Abstract
Our genome adapts slowly to changing conditions of existence. Many diseases of civilisation result from mismatches between our Paleolithic genome and the rapidly changing environment, including our diet. The objective of the present study was to reconstruct multiple Paleolithic diets to estimate the ranges of nutrient intakes upon which humanity evolved. A database of, predominantly East African, plant and animal foods (meat/fish) was used to model multiple Paleolithic diets, using two pathophysiological constraints (i.e. protein < 35 energy % (en%) and linoleic acid (LA) >1.0 en%), at known hunter-gatherer plant/animal food intake ratios (range 70/30-30/70 en%/en%). We investigated selective and non-selective savannah, savannah/aquatic and aquatic hunter-gatherer/scavenger foraging strategies. We found (range of medians in en%) intakes of moderate-to-high protein (25-29), moderate-to-high fat (30-39) and moderate carbohydrates (39-40). The fatty acid composition was SFA (11.4-12.0), MUFA (5.6-18.5) and PUFA (8.6-15.2). The latter was high in α-linolenic acid (ALA) (3.7-4.7 en%), low in LA (2.3-3.6 en%), and high in long-chain PUFA (LCP; 4.75-25.8 g/d), LCP n-3 (2.26-17.0 g/d), LCP n-6 (2.54-8.84 g/d), ALA/LA ratio (1.12-1.64 g/g) and LCP n-3/LCP n-6 ratio (0.84-1.92 g/g). Consistent with the wide range of employed variables, nutrient intakes showed wide ranges. We conclude that compared with Western diets, Paleolithic diets contained consistently higher protein and LCP, and lower LA. These are likely to contribute to the known beneficial effects of Paleolithic-like diets, e.g. through increased satiety/satiation. Disparities between Paleolithic, contemporary and recommended intakes might be important factors underlying the aetiology of common Western diseases. Data on Paleolithic diets and lifestyle, rather than the investigation of single nutrients, might be useful for the rational design of clinical trials.
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Zhu MJ, Ma Y, Long NM, Du M, Ford SP. Maternal obesity markedly increases placental fatty acid transporter expression and fetal blood triglycerides at midgestation in the ewe. Am J Physiol Regul Integr Comp Physiol 2010; 299:R1224-31. [PMID: 20844260 DOI: 10.1152/ajpregu.00309.2010] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Obesity of women at conception is increasing, a condition associated with offspring obesity. We hypothesized that maternal obesity increases placental fatty acid transporter (FATP) expression, enhancing delivery of fatty acids to their fetuses. Sheep are a commonly utilized biomedical model for pregnancy studies. Nonpregnant ewes were randomly assigned to a control group [100% of National Research Council (NRC) recommendations] or obese group (OB, 150% of NRC) from 60 days before conception to 75 or 135 days of gestation (dG; term = 150 dG), when placental cotyledonary tissue was collected for analysis. Fetuses of OB ewes were markedly heavier (P < 0.05) on 75 dG than fetuses from control ewes, but this difference disappeared by 135 dG. Maternal obesity markedly increased (P < 0.05) cholesterol and triglyceride concentrations of both maternal and fetal blood. There is no difference in lipoprotein lipase mRNA expression between control and OB group at either gestational age. On 75 dG, the mRNA expression of FATP1 (P < 0.05), FATP4 (P = 0.08), and fatty acid translocase CD (cluster of differentiation) 36 (P < 0.05) proteins were more enhanced in cotyledonary tissue from OB than control ewes; consistently, protein expression of FATP1 and FATP4 was increased (P < 0.05). Similarly, on 135 dG, the mRNA levels of FATP1, FATP4, and CD36 were all higher (P < 0.05), but only FATP4 protein content was enhanced (P < 0.05) in OB cotyledonary tissue. Peroxisome proliferator-activated receptor (PPAR)-γ regulates the expression of FATPs. Both the mRNA expression and protein content of PPARγ were increased in OB cotyledonary in the midgestation. In conclusion, maternal obesity enhances the mRNA expression and protein content of FATPs in cotyledonary in the midgestation, which is associated with higher PPARγ content in cotyledonary.
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Affiliation(s)
- Mei J Zhu
- Dept. of Animal Science, Univ. of Wyoming, Laramie, WY 82071, USA.
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240
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Denison FC, Roberts KA, Barr SM, Norman JE. Obesity, pregnancy, inflammation, and vascular function. Reproduction 2010; 140:373-85. [DOI: 10.1530/rep-10-0074] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Maternal obesity is associated with increased morbidity and mortality for both mother and offspring. The mechanisms underlying the increased risk associated with maternal obesity are not well understood. In non-pregnant populations, many of the complications of obesity are thought to be mediated in part by inflammation and its sequelae. Recent studies suggest that a heightened inflammatory response may also be involved in mediating adverse clinical outcomes during pregnancy. This review summarizes our current knowledge about adipose tissue biology, and its role as an endocrine and inflammatory organ. The evidence for inflammation as a key mediator of adverse pregnancy outcome is also presented, focusing on the role of inflammation in adipose tissue, systemic inflammation, the placenta, and vascular endothelium.
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241
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Miyake T, Akbar SMF, Yoshida O, Chen S, Hiasa Y, Matsuura B, Abe M, Onji M. Impaired dendritic cell functions disrupt antigen-specific adaptive immune responses in mice with nonalcoholic fatty liver disease. J Gastroenterol 2010; 45:859-67. [PMID: 20195647 DOI: 10.1007/s00535-010-0218-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Accepted: 01/29/2010] [Indexed: 02/04/2023]
Abstract
BACKGROUND/AIMS The magnitude of antigen-specific immunity was assessed in a murine model of nonalcoholic fatty liver diseases (NAFLD). Because antigen-specific immunity was diminished in NAFLD mice, the underlying mechanisms were evaluated through analysis of the functions of antigen-presenting dendritic cells (DC) and other immunocytes. METHODS For 12 weeks, NAFLD mice received a high-fat (60%) and high-calorie (520 kcal/100 g) diet. C57BL/6 mice (controls) received a standard diet. NAFLD mice and control mice were immunized with hepatitis B vaccine containing hepatitis B surface antigen (HBsAg) and hepatitis B core antigen (HBcAg). Antibody to HBsAg (anti-HBs), HBsAg and HBcAg-specific cellular immune response and functions of whole spleen cells, T lymphocytes, B lymphocytes and spleen DCs of NAFLD and control mice were assessed in vitro. RESULTS Levels of anti-HBs and the magnitude of proliferation of HBsAg and HBcAg-specific lymphocytes were significantly lower in NAFLD mice than control mice (P < 0.05). The spleen cells of NAFLD mice produced significantly higher levels of inflammatory cytokines (P < 0.05) and exhibited significantly increased T cell proliferation compared with control mice (P < 0.05). However, the antigen processing and presenting capacities of spleen DCs were significantly decreased in NAFLD mice compared with control mice (P < 0.05). Palmitic acid, a saturated fatty acid, caused diminished antigen processing and presenting capacity of both murine and human DCs. CONCLUSIONS Nonalcoholic fatty liver disease mice exhibit decreased magnitudes of antigen-specific humoral and cellular immune responses. This effect is mainly, if not solely, due to impaired antigen processing and presentation capacities of DC.
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Affiliation(s)
- Teruki Miyake
- Department of Gastroenterology and Metabology, Ehime University Graduate School of Medicine, Toon, Ehime 791-0295, Japan
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242
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Innate immunity and adipose tissue biology. Trends Immunol 2010; 31:228-35. [PMID: 20434953 DOI: 10.1016/j.it.2010.03.001] [Citation(s) in RCA: 194] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 03/01/2010] [Accepted: 03/24/2010] [Indexed: 12/20/2022]
Abstract
The understanding of the role of adipose tissue has changed from a lipid storage organ to an endocrine and immunologically active organ. Here, we summarize the evidence for an important role of adipose tissue in innate immunity. The review focuses on the expression and function of Toll-like receptors (TLRs) in adipocytes and on the role of adipose tissue macrophages. The dual activation of TLR4 in adipocytes by lipopolysaccharide and fatty acids represents a molecular gate that connects innate immunity with metabolism. Dichotomic molecules derived from ancient precursor molecules control metabolism and immune function. Visceral adipose tissue is infiltrated by macrophages in obesity, and there is local crosstalk between these two types of cells, leading to an inflammatory transformation of adipose tissue.
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243
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DAMPening inflammation by modulating TLR signalling. Mediators Inflamm 2010; 2010. [PMID: 20706656 PMCID: PMC2913853 DOI: 10.1155/2010/672395] [Citation(s) in RCA: 652] [Impact Index Per Article: 46.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2009] [Accepted: 04/20/2010] [Indexed: 12/12/2022] Open
Abstract
Damage-associated molecular patterns (DAMPs) include endogenous intracellular molecules released by activated or necrotic cells and extracellular matrix (ECM) molecules that are upregulated upon injury or degraded following tissue damage. DAMPs are vital danger signals that alert our immune system to tissue damage upon both infectious and sterile insult. DAMP activation of Toll-like receptors (TLRs) induces inflammatory gene expression to mediate tissue repair. However, DAMPs have also been implicated in diseases where excessive inflammation plays a key role in pathogenesis, including rheumatoid arthritis (RA), cancer, and atherosclerosis. TLR activation by DAMPs may initiate positive feedback loops where increasing tissue damage perpetuates pro-inflammatory responses leading to chronic inflammation. Here we explore the current knowledge about distinct signalling cascades resulting from self TLR activation. We also discuss the involvement of endogenous TLR activators in disease and highlight how specifically targeting DAMPs may yield therapies that do not globally suppress the immune system.
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244
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Fatty acids regulate CREBh via transcriptional mechanisms that are dependent on proteasome activity and insulin. Mol Cell Biochem 2010; 344:99-107. [PMID: 20607591 DOI: 10.1007/s11010-010-0533-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 06/23/2010] [Indexed: 10/19/2022]
Abstract
Excess fatty acids are closely associated with metabolic dysfunction. The deleterious effects of fatty acids relate, in part, to their ability to up-regulate pro-inflammatory cytokines and propagate a state of systemic inflammation. CREBh is a recently identified transcription factor that appears to be required for hepatic synthesis of C-reactive protein. Recent data suggest that fatty acids can up-regulate CREBh, thus establishing a potential molecular link between fatty acids and inflammation. The aim of this study was to examine the nature and mechanisms of fatty acid-mediated regulation of CREBh. H4IIE liver cells were incubated in the absence or presence of varying concentrations (50-500 μM) of albumin-bound, long-chain saturated (palmitate, stearate) or unsaturated (oleate, linoleate) fatty acids (1-16 h). All fatty acids significantly increased CREBh gene expression via transcriptional mechanisms, at concentrations as low as 50 μM. Palmitate- or oleate-mediated up-regulation of CREBh was not inhibited by triacsin C, an inhibitor of long-chain fatty acyl CoA synthetase, or by the PPARα antagonist, MK886. Inhibition of proteasome activity with MG132 or lactacystin, or inclusion of insulin reduced palmitate- and oleate-mediated increases in CREBh mRNA. Finally, we examined fatty acid regulation of CREBh in vivo. Male Wistar rats were exposed to a 4-h pancreatic clamp combined with infusion of saline or a mixed lipid emulsion. CREBh mRNA and protein were significantly increased in rats exposed to the lipid infusion compared to the saline group. Collectively, these results may have important implications for metabolic diseases characterized by excess fatty acids, insulin resistance, and inflammation.
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245
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Release of inflammatory mediators by human adipose tissue is enhanced in obesity and primarily by the nonfat cells: a review. Mediators Inflamm 2010; 2010:513948. [PMID: 20508843 PMCID: PMC2874930 DOI: 10.1155/2010/513948] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 01/27/2010] [Accepted: 02/23/2010] [Indexed: 02/08/2023] Open
Abstract
This paper considers the role of putative adipokines that might be involved in the enhanced inflammatory response of human adipose tissue seen in obesity. Inflammatory adipokines [IL-6, IL-10, ACE, TGFbeta1, TNFalpha, IL-1beta, PAI-1, and IL-8] plus one anti-inflammatory [IL-10] adipokine were identified whose circulating levels as well as in vitro release by fat are enhanced in obesity and are primarily released by the nonfat cells of human adipose tissue. In contrast, the circulating levels of leptin and FABP-4 are also enhanced in obesity and they are primarily released by fat cells of human adipose tissue. The relative expression of adipokines and other proteins in human omental as compared to subcutaneous adipose tissue as well as their expression in the nonfat as compared to the fat cells of human omental adipose tissue is also reviewed. The conclusion is that the release of many inflammatory adipokines by adipose tissue is enhanced in obese humans.
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247
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Mediators of inflammation in polycystic ovary syndrome in relation to adiposity. Mediators Inflamm 2010; 2010:758656. [PMID: 20396393 PMCID: PMC2852606 DOI: 10.1155/2010/758656] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2009] [Accepted: 03/18/2010] [Indexed: 11/25/2022] Open
Abstract
Polycystic ovary syndrome (PCOS) is a common endocrine disorder in women of reproductive age group and is associated with a higher cardiovascular risk. Obesity, mainly visceral adiposity, is prevalent in patients with PCOS. Obesity is associated with low-grade inflammation and raised inflammatory cytokines, both of which are also described in patients with PCOS. In this paper, the potential relationships between fat distribution, adipocyte dysfunction and, altered inflammatory markers in patients with PCOS have been discussed.
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248
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van den Berg SA, Guigas B, Bijland S, Ouwens M, Voshol PJ, Frants RR, Havekes LM, Romijn JA, van Dijk KW. High levels of dietary stearate promote adiposity and deteriorate hepatic insulin sensitivity. Nutr Metab (Lond) 2010; 7:24. [PMID: 20346174 PMCID: PMC2852377 DOI: 10.1186/1743-7075-7-24] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Accepted: 03/27/2010] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Relatively little is known about the role of specific saturated fatty acids in the development of high fat diet induced obesity and insulin resistance. Here, we have studied the effect of stearate in high fat diets (45% energy as fat) on whole body energy metabolism and tissue specific insulin sensitivity. METHODS C57Bl/6 mice were fed a low stearate diet based on palm oil or one of two stearate rich diets, one diet based on lard and one diet based on palm oil supplemented with tristearin (to the stearate level of the lard based diet), for a period of 5 weeks. Ad libitum fed Oxidative metabolism was assessed by indirect calorimetry at week 5. Changes in body mass and composition was assessed by DEXA scan analysis. Tissue specific insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamp analysis and Western blot at the end of week 5. RESULTS Indirect calorimetry analysis revealed that high levels of dietary stearate resulted in lower caloric energy expenditure characterized by lower oxidation of fatty acids. In agreement with this metabolic phenotype, mice on the stearate rich diets gained more adipose tissue mass. Whole body and tissue specific insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamp and analysis of insulin induced PKBser473 phosphorylation. Whole body insulin sensitivity was decreased by all high fat diets. However, while insulin-stimulated glucose uptake by peripheral tissues was impaired by all high fat diets, hepatic insulin sensitivity was affected only by the stearate rich diets. This tissue-specific pattern of reduced insulin sensitivity was confirmed by similar impairment in insulin-induced phosphorylation of PKBser473 in both liver and skeletal muscle. CONCLUSION In C57Bl/6 mice, 5 weeks of a high fat diet rich in stearate induces a metabolic state favoring low oxidative metabolism, increased adiposity and whole body insulin resistance characterized by severe hepatic insulin resistance. These results indicate that dietary fatty acid composition per sé rather than dietary fat content determines insulin sensitivity in liver of high fat fed C57Bl/6 mice.
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Affiliation(s)
- Sjoerd Aa van den Berg
- Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands.
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Bauer S, Weigert J, Neumeier M, Wanninger J, Schäffler A, Luchner A, Schnitzbauer AA, Aslanidis C, Buechler C. Low-abundant adiponectin receptors in visceral adipose tissue of humans and rats are further reduced in diabetic animals. Arch Med Res 2010; 41:75-82. [PMID: 20470935 DOI: 10.1016/j.arcmed.2010.02.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Accepted: 01/12/2010] [Indexed: 12/22/2022]
Abstract
BACKGROUND AND AIMS Adipose tissue is an endocrine organ that releases various proteins that may also exert autocrine/paracrine effects. The antidiabetic adipokine adiponectin acts through two receptors, AdipoR1 and AdipoR2, but so far mainly mRNA expression has been measured in adipocytes and adipose tissues. Therefore, we aimed to analyze AdipoR1 and AdipoR2 proteins in adipocytes and paired samples of subcutaneous and visceral adipocytes/adipose tissue. METHODS AdipoR1 and AdipoR2 mRNA and protein expression were determined in adipocytes and paired samples of subcutaneous and visceral adipose tissue of humans and rats. RESULTS AdipoR1 and AdipoR2 proteins were similarly abundant in preadipocytes and mature adipocytes despite an induction of mRNA expression during differentiation. Differentiation of 3T3-L1 cells in the presence of palmitic acid did not alter adiponectin receptor proteins but metformin and fenofibrate upregulated AdipoR2 within 24 h of incubation. AdipoR2 protein was significantly lower in human visceral compared to subcutaneous fat, and both receptors were reduced in visceral adipocytes. In rat tissues both receptors were reduced in visceral fat. In diabetic animals AdipoR2 protein, but not mRNA, was lower in both fat depots compared to similarly obese rats with normal glucose disposal. AdipoR1 was only reduced in subcutaneous adipose tissue of diabetic animals where mRNA expression was induced. CONCLUSIONS These data indicate that mRNA expression is not suitable to predict adiponectin receptor protein. Low adiponectin receptors in visceral adipocytes and adipose tissue and further suppression in adipose tissue of insulin-resistant animals indicate disturbed adiponectin bioactivity.
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Affiliation(s)
- Sabrina Bauer
- Department of Internal Medicine I, Regensburg University Hospital, D-93042 Regensburg, Germany
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Kopp A, Buechler C, Bala M, Neumeier M, Schölmerich J, Schäffler A. Toll-like receptor ligands cause proinflammatory and prodiabetic activation of adipocytes via phosphorylation of extracellular signal-regulated kinase and c-Jun N-terminal kinase but not interferon regulatory factor-3. Endocrinology 2010; 151:1097-108. [PMID: 20130114 DOI: 10.1210/en.2009-1140] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Here, we aim to investigate the mechanisms of Toll-like receptor (TLR)-induced prodiabetic and proinflammatory activation of adipocytes and to detect differences in the responsiveness of TLRs to their respective ligands between adipocytes isolated from inflamed vs. noninflamed adipose tissue. Experiments using specific ligands for all known TLRs were performed in murine 3T3-L1 adipocytes and in human adipocytes isolated from noninflamed and inflamed adipose tissue. IL-6 and monocyte chemoattractant protein-1 (MCP-1) release were measured by ELISA. The expression of the signal transduction proteins phospho-extracellular signal-regulated kinase (P-Erk), P-c-Jun N-terminal kinase (JNK), and P-interferon regulatory factor-3 was investigated by Western blot analysis. Additionally, functional inhibitors of MAPK kinase-1/-2 and JNK-1/-2 were used in the stimulation experiments. Activation of TRL4 by lipopolysaccharide (LPS) and TLR1/2 by Pam(3)Cys up-regulates IL-6 and MCP-1 release in adipocytes via specific activation of Erk. Stimulation of adipocytes by macrophage activating lipopeptide-2 (MALP-2) induces MCP-1 but has no effect on IL-6 release. This stimulatory effect on MCP-1 release is antagonized by inhibition of both mitogen-activated protein kinase-1/-2 and JNK-1/-2. Phosphorylation of Erk and JNK is up-regulated after stimulation by MALP-2. In human adipocytes isolated from noninflamed adipose tissue, LPS and Pam(3)Cys, but not MALP-2, are potent inducers of IL-6 and MCP-1. MALP-2 is able to induce IL-6 and MCP-1 release in adipocytes isolated from inflamed adipose tissue, whereas these adipocytes lost their ability to respond to LPS. The present results point to a role of the adipose tissue in innate immunity. TLR-ligand-induced proinflammatory and prodiabetic activation of adipocytes might couple visceral adipose tissue dysfunction with insulin resistance and type 2 diabetes mellitus.
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Affiliation(s)
- Andrea Kopp
- Department of Internal Medicine I, University of Regensburg, D-93042 Regensburg, Germany
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