title: The response of human macrophages to β-glucans depends on the inflammatory milieu.
abstract: BACKGROUND
  β-glucans are fungal cell wall components that bind to the C-type lectin-like receptor dectin-1. Polymorphisms of dectin-1 gene are associated with susceptibility to invasive fungal infection and medically refractory ulcerative colitis. The purpose of this study has been addressing the response of human macrophages to β-glucans under different conditions mimicking the composition of the inflammatory milieu in view of the wide plasticity and large range of phenotypical changes showed by these cells, and the relevant role of dectin-1 in several pathophysiological conditions.
  
  
  RESULTS
  Serum-differentiated macrophages stimulated with β-glucans showed a low production of TNFα and IL-1β, a high production of IL-6 and IL-23, and a delayed induction of cyclooxygenase-2 and PGE2 biosynthesis that resembled the responses elicited by crystals and those produced when phagosomal degradation of the phagocytic cargo increases ligand access to intracellular pattern recognition receptors. Priming with a low concentration of LPS produced a rapid induction of cyclooxygenase-2 and a synergistic release of PGE2. When the differentiation of the macrophages was carried out in the presence of M-CSF, an increased expression of dectin-1 B isoform was observed. In addition, this treatment made the cells capable to release arachidonic acid in response to β-glucan.
  
  
  CONCLUSIONS
  These results indicate that the macrophage response to fungal β-glucans is strongly influenced by cytokines and microbial-derived factors that are usual components of the inflammatory milieu. These responses can be sorted into three main patterns i) an elementary response dependent on phagosomal processing of pathogen-associated molecular patterns and/or receptor-independent, direct membrane binding linked to the immunoreceptor tyrosine-based activation motif-bearing transmembrane adaptor DNAX-activating protein 12, ii) a response primed by TLR4-dependent signals, and iii) a response dependent on M-CSF and dectin-1 B isoform expression that mainly signals through the dectin-1 B/spleen tyrosine kinase/cytosolic phospholipase A2 route.
authors: Instituto de Biología y Genética Molecular, CSIC, Valladolid, Spain.
authors: Cristina
authors: C
authors: Municio
authors: Yolanda
authors: Y
authors: Alvarez
authors: Olimpio
authors: O
authors: Montero
authors: Etzel
authors: E
authors: Hugo
authors: Mario
authors: M
authors: Rodríguez
authors: Esther
authors: E
authors: Domingo
authors: Sara
authors: S
authors: Alonso
authors: Nieves
authors: N
authors: Fernández
authors: Mariano Sánchez
authors: MS
authors: Crespo
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism; D051546:Cyclooxygenase 2 / Q000378:metabolism; D016207:Cytokines / Q000096:biosynthesis; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D015232:Dinoprostone / Q000096:biosynthesis; D004789:Enzyme Activation; D017353:Gene Deletion; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000276:immunology* / Q000378:metabolism*; D037181:Lectins, C-Type / Q000235:genetics; D008264:Macrophages / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D015054:Zymosan / Q000276:immunology / Q000378:metabolism; D047071:beta-Glucans / Q000276:immunology* / Q000378:metabolism; D000099181:Dectin-1
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D016718:Arachidonic Acid; D051546:Cyclooxygenase 2; D016207:Cytokines; D015232:Dinoprostone; D037181:Lectins, C-Type; D016328:NF-kappa B; D015054:Zymosan; D047071:beta-Glucans; D000099181:Dectin-1
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