title: Mgat2 ablation in the myeloid lineage leads to defective glycoantigen T cell responses.
abstract: N-linked glycosylation is a central regulatory factor that influences the immune system in varied and profound ways, including leukocyte homing, T cell receptor signaling and others. Moreover, N-glycan branching has been demonstrated to change as a function of infection and inflammation. Our previous findings suggest that complex-type N-glycans on the class II major histocompatibility complex play an important role in antigen selection within antigen presenting cells (APCs) such that highly branched N-glycans promote polysaccharide (glycoantigen, GlyAg) presentation following Toll-like receptor 2 (TLR2)-dependent antigen processing. In order to explore the impact of N-glycan branching on the myeloid-derived APC population without the confounding problems of altering the branching of lymphocytes and non-hematopoietic cells, we created a novel myeloid-specific knockout of the β-1,2-N-acetylglucosaminyltransferase II (Mgat2) enzyme. Using this novel mouse, we found that the reduction in multi-antennary N-glycans characteristic of Mgat2 ablation had no impact on GlyAg-mediated TLR2 signaling. Likewise, no deficits in antigen uptake or cellular homing to lymph nodes were found. However, we discovered that Mgat2 ablation prevented GlyAg presentation and T cell activation in vitro and in vivo without apparent alterations in protein antigen response or myeloid-mediated protection from infection. These findings demonstrate that GlyAg presentation can be regulated by the N-glycan branching pattern of APCs, thereby establishing an in vivo model where the T cell-dependent activity of GlyAgs can be experimentally distinguished from GlyAg-mediated stimulation of the innate response through TLR2.
authors: Department of Pathology.
authors: Sean O
authors: SO
authors: Ryan
authors: Sixto M
authors: SM
authors: Leal
authors: Derek W
authors: DW
authors: Abbott
authors: Eric
authors: E
authors: Pearlman
authors: Brian A
authors: BA
authors: Cobb
mesh_terms: D000818:Animals; D017951:Antigen Presentation; D000938:Antigen-Presenting Cells / Q000276:immunology; D017353:Gene Deletion; D008213:Lymphocyte Activation; D051379:Mice; D008810:Mice, Inbred C57BL; D022423:Myeloid Cells / Q000276:immunology*; D017351:N-Acetylglucosaminyltransferases / Q000235:genetics / Q000378:metabolism*; D011134:Polysaccharides / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology*; D051195:Toll-Like Receptor 2 / Q000378:metabolism
chemical_list: D011134:Polysaccharides; C493486:Tlr2 protein, mouse; D051195:Toll-Like Receptor 2; D017351:N-Acetylglucosaminyltransferases; C063313:alpha-1,6-mannosyl-glycoprotein beta-1,2-N-acetylglucosaminyltransferase
keywords: CDG-IIa; MHC class II; T lymphocyte; antigen presentation; glycoantigen