Integrating N-glycan and CODEX imaging reveal cell-specific protein glycosylation in healthy human lung

Abstract

N-linked glycosylation, the major post-translational modification of cellular proteins, is important for proper lung functioning, serving to fold, traffic, and stabilize protein structures and to mediate various cell-cell recognition events. Identifying cell-specific N-glycan structures in human lungs is critical for understanding the chemistry and mechanisms that guide cell-cell and cell-matrix interactions and determining nuanced functions of specific N-glycosylation. Our study, which used matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) combined with co-detection by indexing (CODEX) to reveal the cellular origin of N-glycans, is a significant step in this direction. This innovative technological combination enabled us to detect and differentiate N-glycans located in the vicinity of cells surrounding airways and blood vessels, parenchyma, submucosal glands, cartilage, and smooth muscles. The potential impact of our findings on future research is immense. For instance, our algorithm for grouping N-glycans based on their functional chemical features, combined with identifying group niches, paves the way for targeted studies. We found that fucosylated N-glycans are dominant around immune cells, tetra antennary N-glycans in the cartilage, high-mannose N-glycans surrounding the bronchus originate from associated collagenous structures, complex fucosylated-tetra antennary-polylactosamine N-glycans are spread over smooth muscle structures and in epithelial cells surrounding arteries, and N-glycans with Hex:6 HexNAc:6 compositions, which, according to our algorithm, can be ascribed to either tetra antennary or bisecting N-glycan, are highly abundant in the parenchyma. The findings suggest cell or region-specific functions for these localized glycan structures.