title: Immunomodulatory glycan lacto-N-fucopentaose III requires clathrin-mediated endocytosis to induce alternative activation of antigen-presenting cells.
abstract: The mechanism of alternative activation of antigen-presenting cells (APCs) is largely unknown. Lacto-N-fucopentaose III (LNFPIII) is a biologically conserved pentasaccharide that contains the Lewis(x) trisaccharide. LNFPIII conjugates and schistosome egg antigens, which contain the Lewis(x) trisaccharide, drive alternative activation of APCs and induce anti-inflammatory responses in vivo, preventing inflammation-based diseases, including psoriasis, transplant organ rejection, and metabolic disease. In this study, we show that LNFPIII conjugates and schistosome egg antigens interact with APCs via a receptor-mediated process, requiring internalization of these molecules through a clathrin/dynamin-dependent but caveolus-independent endocytic pathway. Using inhibitors/small interfering RNA (siRNA) against dynamin and clathrin, we show for the first time that endocytosis of Lewis(x)-containing glycans is required to drive alternative maturation of antigen-presenting cells and Th2 immune responses. We identified mouse SIGNR-1 as a cell surface receptor for LNFPIII conjugates. Elimination of SIGNR-1 showed no effect on uptake of LNFPIII conjugates, suggesting that other receptors bind to and facilitate uptake of LNFPIII conjugates. We demonstrate that disruption of actin filaments partially prevented the entry of LNFPIII conjugates into APCs and that LNFPIII colocalizes with both early and late endosomal markers and follows the classical endosomal pathway leading to lysosome maturation. The results of this study show that the ability of LNFPIII to induce alternative activation utilizes a receptor-mediated process that requires a dynamin-dependent endocytosis. Thus, key steps have been defined in the previously unknown mechanism of alternative activation that ultimately leads to induction of anti-inflammatory responses.
authors.affiliation: Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA.
authors.forename: Leena
authors.initials: L
authors.lastname: Srivastava
authors.forename: Smanla
authors.initials: S
authors.lastname: Tundup
authors.forename: Beak-San
authors.initials: BS
authors.lastname: Choi
authors.forename: Thomas
authors.initials: T
authors.lastname: Norberg
authors.forename: Donald
authors.initials: D
authors.lastname: Harn
mesh_terms: D000606:Amino Sugars / Q000276:immunology* / Q000378:metabolism; D000818:Animals; D000938:Antigen-Presenting Cells / Q000502:physiology*; D000947:Antigens, Helminth; D015496:CD4-Positive T-Lymphocytes; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism; D002460:Cell Line; D002966:Clathrin / Q000378:metabolism*; D018920:Coculture Techniques; D003713:Dendritic Cells; D004705:Endocytosis / Q000502:physiology*; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D037181:Lectins, C-Type / Q000235:genetics / Q000378:metabolism; D008264:Macrophages; D051379:Mice; D011134:Polysaccharides / Q000276:immunology* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D012550:Schistosoma mansoni / Q000378:metabolism*; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin
chemical_list: D000606:Amino Sugars; D000947:Antigens, Helminth; D015815:Cell Adhesion Molecules; D002966:Clathrin; D037181:Lectins, C-Type; D011134:Polysaccharides; D011956:Receptors, Cell Surface; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin; C434666:lacto-N-fucopentaose III