title: ICOS-induced B7h shedding on B cells is inhibited by TLR7/8 and TLR9.
abstract: We report in this study that B7h, the ligand for the ICOS costimulatory receptor, is rapidly shed from mouse B cells following either ICOS binding or BCR engagement. Shedding occurs through proteolytic cleavage that releases the extracellular ICOS-binding region of B7h. Prior exposure of B7h-expressing APCs to ICOS-expressing cells inhibits their subsequent ability to costimulate IFN-gamma and IL-4 production from CD4+ T cells. Shedding is regulated as TLR7/8 and TLR9 ligands inhibit B7h shedding. A shedding-resistant B7h mutant elicits greater costimulation of IFN-gamma production from CD4+ T cells than does wild-type B7h. These data define shedding of B7h as a novel mechanism for controlling costimulatory signaling by B7-CD28 family members that is regulated on B cells by TLR signaling.
authors.affiliation: Immunology Division, Cancer Research Laboratory, Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Eric C
authors.initials: EC
authors.lastname: Logue
authors.forename: Sonia
authors.initials: S
authors.lastname: Bakkour
authors.forename: Michael M
authors.initials: MM
authors.lastname: Murphy
authors.forename: Hector
authors.initials: H
authors.lastname: Nolla
authors.forename: William C
authors.initials: WC
authors.lastname: Sha
mesh_terms: D000818:Animals; D000945:Antigens, Differentiation, T-Lymphocyte / Q000502:physiology*; D001323:Autoantibodies / Q000096:biosynthesis; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D016466:CHO Cells; D002478:Cells, Cultured; D018920:Coculture Techniques; D006224:Cricetinae; D003412:Cricetulus; D015536:Down-Regulation / Q000276:immunology; D060945:Inducible T-Cell Co-Stimulator Ligand; D060889:Inducible T-Cell Co-Stimulator Protein; D007371:Interferon-gamma / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D011506:Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000276:immunology; D051199:Toll-Like Receptor 7 / Q000502:physiology*; D051200:Toll-Like Receptor 8 / Q000502:physiology*; D051217:Toll-Like Receptor 9 / Q000502:physiology*
chemical_list: D000945:Antigens, Differentiation, T-Lymphocyte; D001323:Autoantibodies; C556694:Icos protein, mouse; C400230:Icosl protein, mouse; D060945:Inducible T-Cell Co-Stimulator Ligand; D060889:Inducible T-Cell Co-Stimulator Protein; D008562:Membrane Glycoproteins; D011506:Proteins; C477038:Tlr7 protein, mouse; C495370:Tlr9 protein, mouse; D051199:Toll-Like Receptor 7; D051200:Toll-Like Receptor 8; D051217:Toll-Like Receptor 9; D007371:Interferon-gamma