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Rubio-Araiz A, Finucane OM, Keogh S, Lynch MA. Anti-TLR2 antibody triggers oxidative phosphorylation in microglia and increases phagocytosis of β-amyloid. J Neuroinflammation 2018; 15:247. [PMID: 30170611 PMCID: PMC6119264 DOI: 10.1186/s12974-018-1281-7] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 08/15/2018] [Indexed: 01/08/2023] Open
Abstract
Background Microglia are multifunctional cells that are primarily neuroprotective and a deficit in their functional integrity is likely to be a contributory factor in the deteriorating neuronal function that occurs with age and neurodegeneration. One aspect of microglial dysfunction is reduced phagocytosis, and this is believed to contribute to the accumulation of amyloid-β (Aβ) in Alzheimer’s disease (AD). Therefore, improving phagocytosis should be beneficial in limiting the amyloidosis that characterises AD. Methods Here, we investigated whether an antibody that targets toll-like receptor (TLR)2 might attenuate the inflammatory and metabolic changes induced by lipopolysaccharide (LPS) and amyloid-β. The impact on phagocytosis was assessed by immunohistochemistry. We evaluated the metabolic changes with the SeaHorse Extracellular Flux Analyser and studied the expression of key enzymes driving glycolysis by western blotting. For all experiments, statistical significance was determined by unpaired Student’s t test and two-way analysis of variance (ANOVA). Results We have reported that, when exposed to an inflammatory stimulus, microglia switch their metabolism towards the metabolically- inefficient glycolysis; this potentially impacts on metabolically demanding functions like phagocytosis. Anti-TLR2 antibody increased phagocytosis of Aβ in LPS + Aβ-stimulated microglia and this was linked with the ability of the antibody to attenuate the LPS + Aβ-triggered inflammasome activation. LPS + Aβ increased glycolysis in microglia and increased the expression of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB)3, an enzyme that plays a key role in driving glycolysis; these effects were inhibited when cells were incubated with the anti-TLR2 antibody. The data also show that antibody treatment increased oxidative metabolism. Conclusions Thus, microglia with an inflammatory phenotype, specifically cells in which the inflammasome is activated, are glycolytic; this may compromise the metabolic efficiency of microglia and thereby provide an explanation for the reduced phagocytic function of the cells. We propose that, by restoring oxidative metabolism and reducing inflammasome activation in microglia, phagocytic function is also restored. Electronic supplementary material The online version of this article (10.1186/s12974-018-1281-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ana Rubio-Araiz
- Trinity College Institute for Neuroscience, Trinity College, Dublin 2, Ireland.
| | - Orla M Finucane
- Trinity College Institute for Neuroscience, Trinity College, Dublin 2, Ireland
| | - Samuel Keogh
- Trinity College Institute for Neuroscience, Trinity College, Dublin 2, Ireland.,Current Address: University College Cork, Cork, Ireland
| | - Marina A Lynch
- Trinity College Institute for Neuroscience, Trinity College, Dublin 2, Ireland
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Holland R, McIntosh AL, Finucane OM, Mela V, Rubio-Araiz A, Timmons G, McCarthy SA, Gun'ko YK, Lynch MA. Inflammatory microglia are glycolytic and iron retentive and typify the microglia in APP/PS1 mice. Brain Behav Immun 2018; 68:183-196. [PMID: 29061364 DOI: 10.1016/j.bbi.2017.10.017] [Citation(s) in RCA: 113] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 10/06/2017] [Accepted: 10/19/2017] [Indexed: 12/18/2022] Open
Abstract
Microglia, like macrophages, can adopt inflammatory and anti-inflammatory phenotypes depending on the stimulus. In macrophages, the evidence indicates that these phenotypes have different metabolic profiles with lipopolysaccharide (LPS)- or interferon-γ (IFNγ)-stimulated inflammatory cells switching to glycolysis as their main source of ATP and interleukin-4 (IL-4)-stimulated cells utilizing oxidative phosphorylation. There is a paucity of information regarding the metabolic signatures of inflammatory and anti-inflammatory microglia. Here, we polarized primary microglia with IFNγ and show that the characteristic increases in tumor necrosis factor-α (TNFα) and nitric oxide synthase 2 (NOS2) were accompanied by increased glycolysis and an increase in the expression of 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB)3, an enzyme that plays a significant role in driving glycolysis. These changes were associated with increased expression of ferritin and retention of iron in microglia. Significantly, retention of iron in microglia increased TNFα expression and also increased glycolysis suggesting that increased intracellular iron concentration may drive the metabolic and/or inflammatory changes. Analysis of microglia prepared from wildtype mice and from transgenic mice that overexpress amyloid precursor protein (APP) and presenilin 1 (PS1; APP/PS1) revealed genotype-related increases in glycolysis, accompanied by increased PFKFB3, and an increase in the expression of ferritin. The data indicate a distinct metabolic signature of inflammatory microglia from APP/PS1 mice that are also distinguishable by their iron handling profiles.
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Affiliation(s)
- R Holland
- Trinity College Institute for Neuroscience, Trinity College, Dublin 2, Ireland
| | - A L McIntosh
- Trinity College Institute for Neuroscience, Trinity College, Dublin 2, Ireland
| | - O M Finucane
- Trinity College Institute for Neuroscience, Trinity College, Dublin 2, Ireland
| | - V Mela
- Trinity College Institute for Neuroscience, Trinity College, Dublin 2, Ireland
| | - A Rubio-Araiz
- Trinity College Institute for Neuroscience, Trinity College, Dublin 2, Ireland
| | - G Timmons
- Trinity College Institute for Neuroscience, Trinity College, Dublin 2, Ireland
| | - S A McCarthy
- School of Chemistry and CRANN, Trinity College, Dublin 2, Ireland
| | - Y K Gun'ko
- School of Chemistry and CRANN, Trinity College, Dublin 2, Ireland
| | - M A Lynch
- Trinity College Institute for Neuroscience, Trinity College, Dublin 2, Ireland.
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Healy NP, Kirwan AM, McArdle MA, Holohan K, Nongonierma AB, Keane D, Kelly S, Celkova L, Lyons CL, McGillicuddy FC, Finucane OM, Murray BA, Kelly PM, Brennan L, FitzGerald RJ, Roche HM. A casein hydrolysate protects mice against high fat diet induced hyperglycemia by attenuating NLRP3 inflammasome-mediated inflammation and improving insulin signaling. Mol Nutr Food Res 2016; 60:2421-2432. [DOI: 10.1002/mnfr.201501054] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Revised: 05/26/2016] [Accepted: 05/31/2016] [Indexed: 12/21/2022]
Affiliation(s)
- Niamh P. Healy
- Nutrigenomics Research Group; Conway Institute of Biomolecular and Biomedical Research; University College Dublin; Dublin Ireland
- Institute of Food and Health; University College Dublin; Dublin Ireland
| | - Anna M. Kirwan
- Nutrigenomics Research Group; Conway Institute of Biomolecular and Biomedical Research; University College Dublin; Dublin Ireland
- Institute of Food and Health; University College Dublin; Dublin Ireland
| | - Maeve A. McArdle
- Nutrigenomics Research Group; Conway Institute of Biomolecular and Biomedical Research; University College Dublin; Dublin Ireland
- Institute of Food and Health; University College Dublin; Dublin Ireland
| | - Kieran Holohan
- Nutrigenomics Research Group; Conway Institute of Biomolecular and Biomedical Research; University College Dublin; Dublin Ireland
- Institute of Food and Health; University College Dublin; Dublin Ireland
| | - Alice B. Nongonierma
- Department of Life Sciences and Food for Health Ireland (FHI); University of Limerick; Castletroy Limerick Ireland
| | - Deirdre Keane
- Nutrigenomics Research Group; Conway Institute of Biomolecular and Biomedical Research; University College Dublin; Dublin Ireland
- Institute of Food and Health; University College Dublin; Dublin Ireland
| | - Stacey Kelly
- Nutrigenomics Research Group; Conway Institute of Biomolecular and Biomedical Research; University College Dublin; Dublin Ireland
- Institute of Food and Health; University College Dublin; Dublin Ireland
| | - Lucia Celkova
- Nutrigenomics Research Group; Conway Institute of Biomolecular and Biomedical Research; University College Dublin; Dublin Ireland
- Institute of Food and Health; University College Dublin; Dublin Ireland
| | - Claire L. Lyons
- Nutrigenomics Research Group; Conway Institute of Biomolecular and Biomedical Research; University College Dublin; Dublin Ireland
- Institute of Food and Health; University College Dublin; Dublin Ireland
| | - Fiona C McGillicuddy
- Nutrigenomics Research Group; Conway Institute of Biomolecular and Biomedical Research; University College Dublin; Dublin Ireland
| | - Orla M Finucane
- Nutrigenomics Research Group; Conway Institute of Biomolecular and Biomedical Research; University College Dublin; Dublin Ireland
- Institute of Food and Health; University College Dublin; Dublin Ireland
| | - Brian A. Murray
- Teagasc Food Research Centre; Moorepark and Food for Health Ireland (FHI); Fermoy County Cork Ireland
| | - Philip M. Kelly
- Teagasc Food Research Centre; Moorepark and Food for Health Ireland (FHI); Fermoy County Cork Ireland
| | - Lorraine Brennan
- Institute of Food and Health; University College Dublin; Dublin Ireland
| | - Richard J. FitzGerald
- Department of Life Sciences and Food for Health Ireland (FHI); University of Limerick; Castletroy Limerick Ireland
| | - Helen M. Roche
- Nutrigenomics Research Group; Conway Institute of Biomolecular and Biomedical Research; University College Dublin; Dublin Ireland
- Institute of Food and Health; University College Dublin; Dublin Ireland
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Finucane OM, Lyons CL, Murphy AM, Reynolds CM, Klinger R, Healy NP, Cooke AA, Coll RC, McAllan L, Nilaweera KN, O'Reilly ME, Tierney AC, Morine MJ, Alcala-Diaz JF, Lopez-Miranda J, O'Connor DP, O'Neill LA, McGillicuddy FC, Roche HM. Monounsaturated fatty acid-enriched high-fat diets impede adipose NLRP3 inflammasome-mediated IL-1β secretion and insulin resistance despite obesity. Diabetes 2015; 64:2116-28. [PMID: 25626736 DOI: 10.2337/db14-1098] [Citation(s) in RCA: 200] [Impact Index Per Article: 22.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 01/14/2015] [Indexed: 12/18/2022]
Abstract
Saturated fatty acid (SFA) high-fat diets (HFDs) enhance interleukin (IL)-1β-mediated adipose inflammation and insulin resistance. However, the mechanisms by which different fatty acids regulate IL-1β and the subsequent effects on adipose tissue biology and insulin sensitivity in vivo remain elusive. We hypothesized that the replacement of SFA for monounsaturated fatty acid (MUFA) in HFDs would reduce pro-IL-1β priming in adipose tissue and attenuate insulin resistance via MUFA-driven AMPK activation. MUFA-HFD-fed mice displayed improved insulin sensitivity coincident with reduced pro-IL-1β priming, attenuated adipose IL-1β secretion, and sustained adipose AMPK activation compared with SFA-HFD-fed mice. Furthermore, MUFA-HFD-fed mice displayed hyperplastic adipose tissue, with enhanced adipogenic potential of the stromal vascular fraction and improved insulin sensitivity. In vitro, we demonstrated that the MUFA oleic acid can impede ATP-induced IL-1β secretion from lipopolysaccharide- and SFA-primed cells in an AMPK-dependent manner. Conversely, in a regression study, switching from SFA- to MUFA-HFD failed to reverse insulin resistance but improved fasting plasma insulin levels. In humans, high-SFA consumers, but not high-MUFA consumers, displayed reduced insulin sensitivity with elevated pycard-1 and caspase-1 expression in adipose tissue. These novel findings suggest that dietary MUFA can attenuate IL-1β-mediated insulin resistance and adipose dysfunction despite obesity via the preservation of AMPK activity.
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Affiliation(s)
- Orla M Finucane
- Nutrigenomics Research Group, Conway Institute of Biomedical and Biomolecular Research, and Institute of Food and Health, University College Dublin, Belfield, Dublin, Ireland
| | - Claire L Lyons
- Nutrigenomics Research Group, Conway Institute of Biomedical and Biomolecular Research, and Institute of Food and Health, University College Dublin, Belfield, Dublin, Ireland
| | - Aoife M Murphy
- Nutrigenomics Research Group, Conway Institute of Biomedical and Biomolecular Research, and Institute of Food and Health, University College Dublin, Belfield, Dublin, Ireland
| | - Clare M Reynolds
- Nutrigenomics Research Group, Conway Institute of Biomedical and Biomolecular Research, and Institute of Food and Health, University College Dublin, Belfield, Dublin, Ireland
| | - Rut Klinger
- School of Biomolecular & Biomedical Science, University College Dublin, Belfield, Dublin, Ireland
| | - Niamh P Healy
- Nutrigenomics Research Group, Conway Institute of Biomedical and Biomolecular Research, and Institute of Food and Health, University College Dublin, Belfield, Dublin, Ireland
| | - Aoife A Cooke
- Nutrigenomics Research Group, Conway Institute of Biomedical and Biomolecular Research, and Institute of Food and Health, University College Dublin, Belfield, Dublin, Ireland
| | - Rebecca C Coll
- Inflammatory Research Group, Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | - Liam McAllan
- Teagasc Food Research Centre, Moorepark, Fermoy, Ireland
| | | | - Marcella E O'Reilly
- Nutrigenomics Research Group, Conway Institute of Biomedical and Biomolecular Research, and Institute of Food and Health, University College Dublin, Belfield, Dublin, Ireland
| | - Audrey C Tierney
- Department of Dietetics and Human Nutrition, La Trobe University, Melbourne, Victoria, Australia
| | - Melissa J Morine
- The Microsoft Research-University of Trento Centre for Computational and Systems Biology, Rovereto, Italy
| | - Juan F Alcala-Diaz
- Lipids and Atherosclerosis Research Unit, Reina Sofía University Hospital, and CIBER Phyisiopathology of Obesity and Nutrition (CIBEROBN), University of Córdoba, Córdoba, Spain
| | - Jose Lopez-Miranda
- Lipids and Atherosclerosis Research Unit, Reina Sofía University Hospital, and CIBER Phyisiopathology of Obesity and Nutrition (CIBEROBN), University of Córdoba, Córdoba, Spain
| | - Darran P O'Connor
- School of Biomolecular & Biomedical Science, University College Dublin, Belfield, Dublin, Ireland
| | - Luke A O'Neill
- Inflammatory Research Group, Biomedical Sciences Institute, Trinity College Dublin, Dublin, Ireland
| | - Fiona C McGillicuddy
- Nutrigenomics Research Group, Conway Institute of Biomedical and Biomolecular Research, and Institute of Food and Health, University College Dublin, Belfield, Dublin, Ireland
| | - Helen M Roche
- Nutrigenomics Research Group, Conway Institute of Biomedical and Biomolecular Research, and Institute of Food and Health, University College Dublin, Belfield, Dublin, Ireland
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Murphy AM, Lyons CL, Finucane OM, Roche HM. Interactions between differential fatty acids and inflammatory stressors-impact on metabolic health. Prostaglandins Leukot Essent Fatty Acids 2015; 92:49-55. [PMID: 24947613 DOI: 10.1016/j.plefa.2014.05.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Revised: 03/11/2014] [Accepted: 05/06/2014] [Indexed: 12/26/2022]
Abstract
Current interest in obesity has established a clear link between diets high in fat and metabolic complications such as Type 2 Diabetes. Dietary fats and their metabolites act as stressors to induce a pro-inflammatory immune response which dysregulates many essential metabolic functions. Recent research suggests that different dietary fats may have varying inflammatory potentials. However the molecular mechanisms involved in the cross talk between dietary fat composition and the 'immuno-metabolism' remain enigmatic. It is probable that lipids, and their derivatives, differentially regulate IL-1β activation and inflammatory signaling via the NLRP3 inflammasome complex. Also from the translational perspective, certain nutrient sensitive genotypes and potential gene nutrient interactions offer the possibility to reduce inflammation through personalized nutrition approaches.
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Affiliation(s)
- Aoife M Murphy
- Nutrigenomics Research Group, UCD Conway Institute & UCD Institute of Food & Health, School of Public Health, University College Dublin, Belfield, Dublin 4, Ireland
| | - Claire L Lyons
- Nutrigenomics Research Group, UCD Conway Institute & UCD Institute of Food & Health, School of Public Health, University College Dublin, Belfield, Dublin 4, Ireland
| | - Orla M Finucane
- Nutrigenomics Research Group, UCD Conway Institute & UCD Institute of Food & Health, School of Public Health, University College Dublin, Belfield, Dublin 4, Ireland
| | - Helen M Roche
- Nutrigenomics Research Group, UCD Conway Institute & UCD Institute of Food & Health, School of Public Health, University College Dublin, Belfield, Dublin 4, Ireland..
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Finucane OM, Reynolds CM, McGillicuddy FC, Harford KA, Morrison M, Baugh J, Roche HM. Macrophage migration inhibitory factor deficiency ameliorates high-fat diet induced insulin resistance in mice with reduced adipose inflammation and hepatic steatosis. PLoS One 2014; 9:e113369. [PMID: 25412423 PMCID: PMC4239060 DOI: 10.1371/journal.pone.0113369] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2013] [Accepted: 10/27/2014] [Indexed: 01/21/2023] Open
Abstract
Macrophage infiltration is a critical determinant of high-fat diet induced adipose tissue inflammation and insulin resistance. The precise mechanisms underpinning the initiation of macrophage recruitment and activation are unclear. Macrophage migration inhibitory factor (MIF), a pro-inflammatory cytokine, displays chemokine-like properties. Circulating MIF levels are elevated during obesity however its role in high-fat diet induced adipose inflammation and insulin resistance remains elusive. Wildtype and MIF-/- C57Bl\6J mice were fed chow or high-fat diet. Body weight and food intake was assessed. Glucose homeostasis was monitored by glucose and insulin tolerance tests. Adipose tissue macrophage recruitment and adipose tissue insulin sensitivity was evaluated. Cytokine secretion from stromal vascular fraction, adipose explants and bone marrow macrophages was measured. Inflammatory signature and insulin sensitivity of 3T3-L1-adipocytes co-cultured with wildtype and MIF-/- macrophage was quantified. Hepatic triacylglyceride levels were assessed. MIF-/- exhibited reduced weight gain. Age and weight-matched obese MIF-/- mice exhibited improved glucose homeostasis coincident with reduced adipose tissue M1 macrophage infiltration. Obese MIF-/- stromal vascular fraction secreted less TNFα and greater IL-10 compared to wildtype. Activation of JNK was impaired in obese MIF-/-adipose, concomitant with pAKT expression. 3T3-L1-adipocytes cultured with MIF-/- macrophages had reduced pro-inflammatory cytokine secretion and improved insulin sensitivity, effects which were also attained with MIF inhibitor ISO-1. MIF-/- liver exhibited reduced hepatic triacyglyceride accumulation, enhanced pAKT expression and reduced NFκB activation. MIF deficiency partially protects from high-fat diet induced insulin resistance by attenuating macrophage infiltration, ameliorating adipose inflammation, which improved adipocyte insulin resistance ex vivo. MIF represents a potential therapeutic target for treatment of high-fat diet induced insulin resistance.
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Affiliation(s)
- Orla M. Finucane
- Institute of Molecular Medicine, School of Medicine, Trinity Centre for Health Sciences, St. James Hospital, Dublin 8, Ireland
- Nutrigenomics Research Group, School of Public Health & Population Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - Clare M. Reynolds
- Nutrigenomics Research Group, School of Public Health & Population Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
- Liggins Institute, University of Auckland, Auckland, New Zealand
| | - Fiona C. McGillicuddy
- Nutrigenomics Research Group, School of Public Health & Population Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - Karen A. Harford
- Nutrigenomics Research Group, School of Public Health & Population Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - Martine Morrison
- Nutrigenomics Research Group, School of Public Health & Population Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - John Baugh
- School of Medicine and Medical Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | - Helen M. Roche
- Nutrigenomics Research Group, School of Public Health & Population Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland
- * E-mail:
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McArdle MA, Finucane OM, Connaughton RM, McMorrow AM, Roche HM. Mechanisms of obesity-induced inflammation and insulin resistance: insights into the emerging role of nutritional strategies. Front Endocrinol (Lausanne) 2013; 4:52. [PMID: 23675368 PMCID: PMC3650620 DOI: 10.3389/fendo.2013.00052] [Citation(s) in RCA: 327] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2012] [Accepted: 04/22/2013] [Indexed: 12/11/2022] Open
Abstract
Obesity and associated chronic inflammation initiate a state of insulin resistance (IR). The secretion of chemoattractants such as MCP-1 and MIF and of cytokines IL-6, TNF-α, and IL-1β, draw immune cells including dendritic cells, T cells, and macrophages into adipose tissue (AT). Dysfunctional AT lipid metabolism leads to increased circulating free fatty acids, initiating inflammatory signaling cascades in the population of infiltrating cells. A feedback loop of pro-inflammatory cytokines exacerbates this pathological state, driving further immune cell infiltration and cytokine secretion and disrupts the insulin signaling cascade. Disruption of normal AT function is causative of defects in hepatic and skeletal muscle glucose homeostasis, resulting in systemic IR and ultimately the development of type 2 diabetes. Pharmaceutical strategies that target the inflammatory milieu may have some potential; however there are a number of safety concerns surrounding such pharmaceutical approaches. Nutritional anti-inflammatory interventions could offer a more suitable long-term alternative; whilst they may be less potent than some pharmaceutical anti-inflammatory agents, this may be advantageous for long-term therapy. This review will investigate obese AT biology, initiation of the inflammatory, and insulin resistant environment; and the mechanisms through which dietary anti-inflammatory components/functional nutrients may be beneficial.
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Affiliation(s)
- Maeve A. McArdle
- Nutrigenomics Research Group, UCD Conway Institute, School of Public Health, Physiotherapy and Population Science, University College DublinDublin, Republic of Ireland
| | - Orla M. Finucane
- Nutrigenomics Research Group, UCD Conway Institute, School of Public Health, Physiotherapy and Population Science, University College DublinDublin, Republic of Ireland
| | - Ruth M. Connaughton
- Nutrigenomics Research Group, UCD Conway Institute, School of Public Health, Physiotherapy and Population Science, University College DublinDublin, Republic of Ireland
| | - Aoibheann M. McMorrow
- Nutrigenomics Research Group, UCD Conway Institute, School of Public Health, Physiotherapy and Population Science, University College DublinDublin, Republic of Ireland
| | - Helen M. Roche
- Nutrigenomics Research Group, UCD Conway Institute, School of Public Health, Physiotherapy and Population Science, University College DublinDublin, Republic of Ireland
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Reynolds CM, McGillicuddy FC, Harford KA, Finucane OM, Mills KHG, Roche HM. Dietary saturated fatty acids prime the NLRP3 inflammasome via TLR4 in dendritic cells-implications for diet-induced insulin resistance. Mol Nutr Food Res 2012; 56:1212-22. [PMID: 22700321 DOI: 10.1002/mnfr.201200058] [Citation(s) in RCA: 122] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2012] [Revised: 04/05/2012] [Accepted: 04/17/2012] [Indexed: 12/25/2022]
Abstract
SCOPE Inflammasome-mediated inflammation is a critical regulator of obesity-induced insulin resistance (IR). We hypothesized that saturated fatty acids (SFA) directly prime the NLRP3 inflammasome via TLR4 concurrent with IR. We focused on dendritic cells (DCs) (CD11c(+) CD11b(+) F4/80(-) ), which are recruited into obese adipose tissue following high-fat diet (HFD) challenge and are a key cell in inflammasome biology. METHODS AND RESULTS C57BL/6 mice were fed HFD for 16 weeks (45% kcal palm oil), glucose homeostasis was monitored by glucose and insulin tolerance tests. Stromal vascular fraction (SVF) cells were isolated from adipose and analyzed for CD11c(+) CD11b(+) F480(-) DC. Following coculture with bone marrow derived DC (BMDC) insulin-stimulated (3) H-glucose transport into adipocytes, IL-1β secretion and caspase-1 activation was monitored. BMDCs primed with LPS (100 ng/mL), linoleic acid (LA; 200 μM), or palmitic acid (PA; 200 μM) were used to monitor inflammasome activation. We demonstrated significant infiltration of DCs into adipose after HFD. HFD-derived DCs reduce adipocyte insulin sensitivity upon coculture co-incident with enhanced adipocyte caspase-1 activation/IL-1β secretion. HFD-derived DCs are skewed toward a pro-inflammatory phenotype with increased IL-1β secretion, IL-1R1, TLR4, and caspase-1 expression. Complementary in vitro experiments demonstrate that TLR4 is critical in propagating SFA-mediated inflammasome activation. CONCLUSION SFA represent metabolic triggers priming the inflammasome, promoting adipocyte inflammation/IR, suggesting direct effects of SFA on inflammasome activation via TLR4.
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Affiliation(s)
- Clare M Reynolds
- Nutrigenomics Research Group, UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
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