title: Control of TNF-induced dendritic cell maturation by hybrid-type N-glycans.
abstract: The activity of α-1,2-mannosidase I is required for the conversion of high-mannose to hybrid-type (ConA reactive) and complex-type N-glycans (Phaseolus vulgaris-leukoagglutinin [PHA-L] reactive) during posttranslational protein N-glycosylation. We recently demonstrated that α-1,2-mannosidase I mRNA decreases in graft-infiltrating CD11c(+) dendritic cells (DCs) prior to allograft rejection. Although highly expressed in immature DCs, little is known about its role in DC functions. In this study, analysis of surface complex-type N-glycan expression by lectin staining revealed the existence of PHA-L(low) and PHA-L(high) subpopulations in murine splenic conventional DCs, as well as in bone marrow-derived DC (BMDCs), whereas plasmacytoid DCs are nearly exclusively PHA-L(high). Interestingly, all PHA-L(high) DCs displayed a strongly reduced responsiveness to TNF-α-induced p38-MAPK activation compared with PHA-L(low) DCs, indicating differences in PHA-L-binding capacities between DCs with different inflammatory properties. However, p38 phosphorylation levels were increased in BMDCs overexpressing α-1,2-mannosidase I mRNA. Moreover, hybrid-type, but not complex-type, N-glycans are required for TNF-α-induced p38-MAPK activation and subsequent phenotypic maturation of BMDCs (MHC-II, CD86, CCR7 upregulation). α-1,2-mannosidase I inhibitor-treated DCs displayed diminished transendothelial migration in response to CCL19, homing to regional lymph nodes, and priming of IFN-γ-producing T cells in vivo. In contrast, the activity of α-1,2-mannosidase I is dispensable for LPS-induced signaling, as well as the DCs' general capability for phenotypic and functional maturation. Systemic application of an α-1,2-mannosidase I inhibitor was able to significantly prolong allograft survival in a murine high-responder corneal transplantation model, further highlighting the importance of N-glycan processing by α-1,2-mannosidase I for alloantigen presentation and T cell priming.
authors.affiliation: Institute of Medical Immunology, Charité University Medicine Berlin, D-13353 Berlin, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Schlickeiser
authors.forename: Svetlana
authors.initials: S
authors.lastname: Stanojlovic
authors.forename: Christine
authors.initials: C
authors.lastname: Appelt
authors.forename: Katrin
authors.initials: K
authors.lastname: Vogt
authors.forename: Simone
authors.initials: S
authors.lastname: Vogel
authors.forename: Stefanie
authors.initials: S
authors.lastname: Haase
authors.forename: Thomas
authors.initials: T
authors.lastname: Ritter
authors.forename: Hans-Dieter
authors.initials: HD
authors.lastname: Volk
authors.forename: Uwe
authors.initials: U
authors.lastname: Pleyer
authors.forename: Birgit
authors.initials: B
authors.lastname: Sawitzki
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000276:immunology; D002454:Cell Differentiation / Q000276:immunology*; D002469:Cell Separation; D016039:Corneal Transplantation; D003713:Dendritic Cells / Q000737:chemistry / Q000166:cytology* / Q000276:immunology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005434:Flow Cytometry; D006085:Graft Survival / Q000187:drug effects / Q000276:immunology*; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D008361:Mannosidases / Q000037:antagonists & inhibitors / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D011134:Polysaccharides / Q000096:biosynthesis / Q000276:immunology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology*
chemical_list: D004791:Enzyme Inhibitors; D011134:Polysaccharides; D014409:Tumor Necrosis Factor-alpha; D008361:Mannosidases; C046090:mannosyl-oligosaccharide 1,2-alpha-mannosidase