title: Differential expression and function of α-mannosidase I in stimulated naive and memory CD4+ T cells.
abstract: N-linked protein glycosylation represents an important cellular process for modifying protein properties. It resembles a cascade of various enzymatic reactions, in which class I α-mannosidases play a central role. We and others have recently shown that N-glycosylation plays a major role for immune functions. We now analyzed the expression and function of α-mannosidase I in CD4(+) naive and memory T cells studying human and murine T cells. Alpha-mannosidase I function was altered by (i) treatment with Kifunensine, a specific inhibitor class I α-mannosidases, (ii) synthetic inhibitory RNA, and (iii) overexpression by retroviral gene transfer. T-cell activation was evaluated by CD69 expression, cytokine production and proliferation. Our results demonstrate (i) that α-mannosidase I transcription is transiently downregulated after T-cell activation with either polyclonal anti-CD3/CD28 antibodies or allogeneic CD19(+) B cells, and (ii) that α-mannosidase I exerts an inhibitory effect on T-cell activation. It is interesting to note that the inhibitory effect was restricted to naive CD4(+) T cells in both systems, human T cells and murine transgenic CD4(+)OT-II cells, whereas human memory T cells and primed CD4(+)OT-II cells remained unaffected. Alpha-mannosidase I inhibition reduced the activation threshold for naive but not already primed CD4(+)OT-II cells as the cells were able to respond to lower ovalbumin peptide concentrations and increased the rejection potential of alloreactive T cells in vivo. Thus, complex N-glycans generated by enzymes such as α-mannosidase I inhibit the activation of naive T cells. These findings could be used to improve the ex vivo priming of naive T cells for adaptive T-cell therapies.
authors.affiliation: Institute of Medical Immunology, Charité-Universitätsmedizin, Berlin, Germany.
authors.forename: Inga
authors.initials: I
authors.lastname: Gebuhr
authors.forename: Kathrin
authors.initials: K
authors.lastname: Keeren
authors.forename: Katrin
authors.initials: K
authors.lastname: Vogt
authors.forename: Conny
authors.initials: C
authors.lastname: Höflich
authors.forename: Christine
authors.initials: C
authors.lastname: Appelt
authors.forename: Ulrike
authors.initials: U
authors.lastname: Schlieer
authors.forename: Christine
authors.initials: C
authors.lastname: Brandt
authors.forename: Christian
authors.initials: C
authors.lastname: Meisel
authors.forename: Hans-Dieter
authors.initials: HD
authors.lastname: Volk
authors.forename: Birgit
authors.initials: B
authors.lastname: Sawitzki
mesh_terms: D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D015703:Antigens, CD / Q000032:analysis; D001402:B-Lymphocytes / Q000276:immunology / Q000378:metabolism; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D020868:Gene Silencing; D006801:Humans; D007156:Immunologic Memory; D008213:Lymphocyte Activation / Q000187:drug effects / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D034741:RNA, Small Interfering / Q000494:pharmacology; D012190:Retroviridae; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D043323:alpha-Mannosidase / Q000037:antagonists & inhibitors / Q000235:genetics / Q000276:immunology / Q000378:metabolism
chemical_list: D000470:Alkaloids; D000906:Antibodies; D015703:Antigens, CD; D004791:Enzyme Inhibitors; D034741:RNA, Small Interfering; C065629:kifunensine; D043323:alpha-Mannosidase