title: Regulation of expression and secretion of galectin-3 in human monocyte-derived dendritic cells.
abstract: Galectin-3 (Gal-3) is a beta-galactoside binding lectin displaying both intracellular and extracellular immune functions. In Schistosoma mansoni infection, Gal-3 has been associated with the induction of a T helper 2 response. Whereas dendritic cells (DCs) play a pivotal role in the regulation of T cell differentiation, little is known about the regulation of Gal-3 expression in DCs. In this study we determined Gal-3 mRNA and protein levels during in vitro differentiation of human monocytes into immature DCs (iDCs), by culturing monocytes in the presence of interleukin-4 (IL-4) and granulocyte-macrophage colony-stimulating factor (GM-CSF). Gal-3 mRNA levels show a moderate, transient increase during iDC generation, accompanied by elevated cell-associated Gal-3 protein. Our data show that culturing monocytes with IL-4 alone strongly increases Gal-3 mRNA levels, whereas GM-CSF induces a low increase in Gal-3 mRNA. The combined data indicate that GM-CSF reduces IL-4 induced Gal-3 mRNA levels during the generation of iDC. Remarkably, stimulation of monocytes with GM-CSF results in secretion of significant amounts of Gal-3 in the medium, whereas iDCs do not release detectable amounts of Gal-3, indicating a suppressive role of IL-4 on GM-CSF induced Gal-3 secretion. Finally, our data demonstrate that all differentiated cell types tested show a significantly lower capacity to bind Gal-3 on the cell surface than monocytes. In conclusion, Gal-3 expression in iDCs is restricted, and Gal-3 protein is localized mainly intracellular, due to the opposite actions of IL-4 and GM-CSF. By these properties, the DCs may be protected against Gal-3 induced phosphatidylserine (PS) exposure and/or apoptosis.
authors.affiliation: Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands.
authors.forename: Caroline M W
authors.initials: CM
authors.lastname: van Stijn
authors.forename: Marloes
authors.initials: M
authors.lastname: van den Broek
authors.forename: Robert
authors.initials: R
authors.lastname: van de Weerd
authors.forename: Michael
authors.initials: M
authors.lastname: Visser
authors.forename: Ismayil
authors.initials: I
authors.lastname: Taşdelen
authors.forename: Boris
authors.initials: B
authors.lastname: Tefsen
authors.forename: Irma
authors.initials: I
authors.lastname: van Die
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D037502:Galectin 3 / Q000096:biosynthesis* / Q000276:immunology; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D016178:Granulocyte-Macrophage Colony-Stimulating Factor / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D015847:Interleukin-4 / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D009000:Monocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D010718:Phosphatidylserines / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis / Q000276:immunology; D012550:Schistosoma mansoni / Q000276:immunology; D012555:Schistosomiasis mansoni / Q000276:immunology / Q000378:metabolism; D018418:Th2 Cells / Q000276:immunology / Q000378:metabolism
chemical_list: D037502:Galectin 3; C508598:IL4 protein, human; D010718:Phosphatidylserines; D012333:RNA, Messenger; D015847:Interleukin-4; D016178:Granulocyte-Macrophage Colony-Stimulating Factor