Unique N-glycosylation signatures in human iPSC derived microglia activated by Aβ oligomer and lipopolysaccharide

Microglia are the immune cells in the central nervous system (CNS) and become pro-inflammatory/activated in Alzheimer’s disease (AD). Cell surface glycosylation plays an important role in immune cells, however, the N-glycosylation and glycosphingolipid (GSL) signatures of activated microglia are poorly understood. Here, we study comprehensive combined transcriptomic and glycomic profiles using human induced pluripotent stem cells-derived microglia (hiMG). Distinct changes in N-glycosylation patterns in Aβ oligomer (AβO) and LPS -treated hiMG were observed. In AβO treated cells, the relative abundance of bisecting N-acetylglucosamine (GlcNAc) N-glycans decreased, corresponding with a downregulation of MGAT3, the gene responsible for bisecting GlcNAc N-glycan formation. The sialylation of N-glycans increased in response to AβO, accompanied by an upregulation of genes involved in N-glycan sialylation (ST3GAL2, 4, and 6). Moreover, we found that the N-glycosylation signature of LPS-induced hiMG differed from that of AβO-induced hiMG. LPS-induced hiMG exhibited a decreased abundance of complex-type N-glycans, aligned with downregulation of mannosidase genes (MAN1A1, MAN2A2, MAN1C1). Fucosylation increased in LPS-induced hiMG, aligned with upregulated fucosyltransferase 4 (FUT4) and downregulated alpha-L-fucosidase 1 (FUCA1) gene expression. However, the GSL profile did not exhibit significant changes in response to AβO or LPS activation. AβO- and LPS- specific glycosylation changes could contribute to impaired microglia function, highlighting glycosylation pathways as potential therapeutic targets for AD.