Alpha-1,2-Mannosidase and Hence N-Glycosylation Are Required for Regulatory T Cell Migration and Allograft Tolerance in Mice

Abstract

BackgroundSpecific immunological unresponsiveness to alloantigens can be induced in vivo by treating mice with a donor alloantigen in combination with a non-depleting anti-CD4 antibody. This tolerance induction protocol enriches for alloantigen reactive regulatory T cells (Treg). We previously demonstrated that alpha-1,2-mannosidase, an enzyme involved in the synthesis and processing of N-linked glycoproteins, is highly expressed in tolerant mice, in both graft infiltrating leukocytes and peripheral blood lymphocytes.Principal FindingsIn this study we have identified that alpha-1,2-mannosidase expression increases in CD25+CD4+ Treg when they encounter alloantigen in vivo. When alpha-1,2-mannosidase enzyme activity was blocked, Treg retained their capacity to suppress T cell proliferation in vitro but were unable to bind to physiologically relevant ligands in vitro. Further in vivo analysis demonstrated that blocking alpha-1,2-mannosidase in Treg resulted in the migration of significantly lower numbers to the peripheral lymph nodes in skin grafted mice following adoptive transfer, where they were less able to inhibit the proliferation of naïve T cells responding to donor alloantigen and hence unable prevent allograft rejection in vivo.SignificanceTaken together, our results suggest that activation of alloantigen reactive Treg results in increased alpha-1,2-mannosidase expression and altered N-glycosylation of cell surface proteins. In our experimental system, altered N-glycosylation is not essential for intrinsic Treg suppressive capacity, but is essential in vivo as it facilitates Treg migration to sites where they can regulate immune priming. Migration of Treg is central to their role in regulating in vivo immune responses and may require specific changes in N-glycosylation upon antigen encounter.

Control of TNF-Induced Dendritic Cell Maturation by Hybrid-Type N-Glycans

“…We also recently found that kifunensine pretreatment of allo-activated T cells that were adoptively transferred into syngeneic RAG 2/2 mice accelerated rejection of skin allografts (I. Gebuhr, K. Keeren, K. Vogt, C. Höflich, C. Appelt, C. Brandt, C. Meisel, H.-D. Volk, and B. Sawitzki, manuscript in preparation). In contrast, it was demonstrated that inhibition of a-1,2-mannosidase I impairs homing of regulatory T cells and their capacity to prevent skin allograft rejection (53). The latter finding might explain why there was no permanent corneal allograft acceptance after cessation of inhibitor treatment in the current study.…”

Nuclear Factor kappa B is central to Marek’s Disease herpesvirus induced neoplastic transformation of CD30 expressing lymphocytes in-vivo

“…f) Immune evasion mechanisms are increased: MAN1A2, (which induces T-reg cell migration and prevents T cell priming [62]), was increased and this supports our previous contention that as neoplastic transformation proceeds, a T-reg-like phenotype is induced [3,6,12]. IRG1 protein and mRNA (p < 0.06) were decreased in the CD30 hi cells.…”

Gene Expression and Methylation Signatures ofMAN2C1are Associated with PTSD

“…Nevertheless, the locus is known to be involved in cancer progression, as its expression appears to modulate tumor growth in in vivo [29,30] experiments. In addition, both in vitro [31,32] and in vivo [32] work has implicated MAN2C1 in T-cell functioning, and yeast two hybrid assays have shown that it interacts with an immune-system related gene, HLA-B associated transcript 2 (BAT2) [33]. Both gene expression [17][18][19] and methylation [16] studies of PTSD have indicated that dysregulation in immune system related genes in peripheral blood are associated with this disorder.…”