Gangliosides (acidic glycosphingolipids) contain ceramide moieties and oligosaccharide chains with sialic acid residue(s). Although gangliosides are well studied in the context of neurological diseases, they have also been linked to infectious diseases, including Staphylococcus aureus (S. aureus). The presence of multiple sialylation sites gives rise to many possible isomeric structures, complicating ganglioside characterization. Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) enables untargeted spatial analysis of gangliosides, among other biomolecules, within tissues. Integrating trapped ion mobility mass spectrometry (TIMS), a gas-phase separation technology, with MALDI IMS, shows great promise for resolving ganglioside isomerism in situ. Isomeric disialogangliosides GD1a and GD1b, highly abundant in mammalian brain tissues, contain two sialic acid residues on their oligosaccharide chain. GD1a has a sialic acid on both the terminal and the inner galactose, whereas GD1b has both residues on the terminal galactose. Immunohistochemical approaches can reveal the localization of GD1a and GD1b species, but provides no information on the ceramide moieties. MALD IMS, on the other hand, can clearly show the localization of GD1s with different ceramide compositions, such as 36:1 and 38:1, but cannot discern between GD1a and GD1b. Our negative ionization mode ion mobility results demonstrate the partial TIMS separation of GD1a and GD1b for both 36:1 and 38:1 ceramide composition directly from murine tissue. The two isomers show similar but distinct localizations within the murine brain and spinal cord tissues. As a case study, S. aureus infected mouse kidney revealed changes in the ganglioside composition at different time points post infection. Preliminary results indicate TIMS-separated isomeric mono/di-sialogangliosides have different localizations within S. aureus abscesses. These results suggest that MALDI TIMS IMS can be used to discern the localization of disialogangliosides that differ in sialic acid position and ceramide composition.

Differential distributions of disialoganglioside isomers -GD1a and GD1b in murine tissue by MALDI TIMS IMS

ACS Spring 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.