Structural determination and Toll-like receptor 2-dependent proinflammatory activity of dimycolyl-diarabino-glycerol from Mycobacterium marinum.
Although it was identified in the cell wall of several pathogenic mycobacteria, the biological properties of dimycolyl-diarabino-glycerol have not been documented yet. In this study an apolar glycolipid, presumably corresponding to dimycolyl-diarabino-glycerol, was purified from Mycobacterium marinum and subsequently identified as a 5-O-mycolyl-β-Araf-(1→2)-5-O-mycolyl-α-Araf-(1→1')-glycerol (designated Mma_DMAG) using a combination of nuclear magnetic resonance spectroscopy and mass spectrometry analyses. Lipid composition analysis revealed that mycolic acids were dominated by oxygenated mycolates over α-mycolates and devoid of trans-cyclopropane functions. Highly purified Mma_DMAG was used to demonstrate its immunomodulatory activity. Mma_DMAG was found to induce the secretion of proinflammatory cytokines (TNF-α, IL-8, IL-1β) in human macrophage THP-1 cells and to trigger the expression of ICAM-1 and CD40 cell surface antigens. This activation mechanism was dependent on TLR2, but not on TLR4, as demonstrated by (i) the use of neutralizing anti-TLR2 and -TLR4 antibodies and by (ii) the detection of secreted alkaline phosphatase in HEK293 cells co-transfected with the human TLR2 and secreted embryonic alkaline phosphatase reporter genes. In addition, transcriptomic analyses indicated that various genes encoding proinflammatory factors were up-regulated after exposure of THP-1 cells to Mma_DMAG. Importantly, a wealth of other regulated genes related to immune and inflammatory responses, including chemokines/cytokines and their respective receptors, adhesion molecules, and metalloproteinases, were found to be modulated by Mma_DMAG. Overall, this study suggests that DMAG may be an active cell wall glycoconjugate driving host-pathogen interactions and participating in the immunopathogenesis of mycobacterial infections.
Université Lille Nord de France, Université Lille1, Unité de Glycobiologie Structurale et Fonctionnelle, UGSF, IFR 147, France. elisabeth.elass@univ-lille1.fr
Elisabeth
E
Elass-Rochard
Yoann
Y
Rombouts
Bernadette
B
Coddeville
Emmanuel
E
Maes
Renaud
R
Blervaque
David
D
Hot
Laurent
L
Kremer
Yann
Y
Guérardel
D019013:CD40 Antigens / Q000276:immunology / Q000378:metabolism; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D006017:Glycolipids / Q000737:chemistry / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D057809:HEK293 Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D018836:Inflammation Mediators / Q000276:immunology / Q000378:metabolism; D018799:Intercellular Adhesion Molecule-1 / Q000276:immunology / Q000378:metabolism; D008264:Macrophages / Q000276:immunology / Q000378:metabolism; D009165:Mycobacterium Infections, Nontuberculous / Q000276:immunology / Q000378:metabolism; D019910:Mycobacterium marinum / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D051195:Toll-Like Receptor 2 / Q000276:immunology / Q000378:metabolism
D019013:CD40 Antigens; D016207:Cytokines; D006017:Glycolipids; C573420:ICAM1 protein, human; D018836:Inflammation Mediators; C495342:TLR2 protein, human; D051195:Toll-Like Receptor 2; D018799:Intercellular Adhesion Molecule-1