GM1 Oligosaccharide Modulates Microglial Activation and α-Synuclein Clearance in a Human In Vitro Model

Neuroinflammation driven by microglial activation and α-synuclein (αSyn) aggregation is one of the central features driving Parkinson's disease (PD) pathogenesis. GM1 ganglioside's oligosaccharide moiety (OligoGM1) has shown neuroprotective potential in PD neuronal models, but its direct effects on inflammation remain poorly defined. This study investigated the ability of OligoGM1 to modulate microglial activation and αSyn handling in a human in vitro model. Human embryonic microglial (HMC3) cells were exposed to αSyn pre-formed fibrils (PFFs) in the presence or absence of OligoGM1. Microglial activation markers, intracellular αSyn accumulation, and cytokine release were assessed by immunofluorescence and ELISA. OligoGM1 had no effect on microglial morphology or cytokine release under basal conditions. Upon αSyn challenge, cells exhibited increased amounts of ionized calcium-binding adaptor molecule 1 (Iba1), triggered receptor expressed on myeloid cells 2 (TREM2), elevated αSyn accumulation, and secreted pro-inflammatory cytokines. OligoGM1 pre-treatment significantly reduced the number and area of Iba1(+) cells, the intracellular αSyn burden in TREM2(+) microglia, and the release of interleukin 6 (IL-6). OligoGM1 selectively attenuated αSyn-induced microglial activation and enhanced αSyn clearance without compromising basal immune function. These findings confirm and support the potential of OligoGM1 as a multitarget therapeutic candidate for PD that is capable of modulating glial reactivity and neuroinflammatory responses.