title: Macrophage migration inhibitory factor deficiency ameliorates high-fat diet induced insulin resistance in mice with reduced adipose inflammation and hepatic steatosis.
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.
authors.affiliation: 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.
authors.forename: Orla M
authors.initials: OM
authors.lastname: Finucane
authors.affiliation: 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.
authors.forename: Clare M
authors.initials: CM
authors.lastname: Reynolds
authors.affiliation: Nutrigenomics Research Group, School of Public Health & Population Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland.
authors.forename: Fiona C
authors.initials: FC
authors.lastname: McGillicuddy
authors.affiliation: Nutrigenomics Research Group, School of Public Health & Population Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland.
authors.forename: Karen A
authors.initials: KA
authors.lastname: Harford
authors.affiliation: Nutrigenomics Research Group, School of Public Health & Population Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland.
authors.forename: Martine
authors.initials: M
authors.lastname: Morrison
authors.affiliation: School of Medicine and Medical Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland.
authors.forename: John
authors.initials: J
authors.lastname: Baugh
authors.affiliation: Nutrigenomics Research Group, School of Public Health & Population Science, UCD Conway Institute, University College Dublin, Dublin 4, Ireland.
authors.forename: Helen M
authors.initials: HM
authors.lastname: Roche
mesh_terms: D016475:3T3 Cells; D000273:Adipose Tissue / Q000276:immunology / Q000378:metabolism; D000818:Animals; D001835:Body Weight; D059305:Diet, High-Fat / Q000009:adverse effects*; D004435:Eating; D005234:Fatty Liver / Q000276:immunology* / Q000517:prevention & control; D007249:Inflammation / Q000276:immunology*; D007333:Insulin Resistance; D019746:Intramolecular Oxidoreductases / Q000172:deficiency*; D008263:Macrophage Migration-Inhibitory Factors / Q000172:deficiency*; D008264:Macrophages / Q000166:cytology / Q000276:immunology*; D051379:Mice; D009765:Obesity / Q000139:chemically induced / Q000276:immunology* / Q000378:metabolism
chemical_list: D008263:Macrophage Migration-Inhibitory Factors; D019746:Intramolecular Oxidoreductases; C076231:Mif protein, mouse