Interaction between tumour cells and macrophages enables cancer cells to evade immune detection and clearance by interfering with macrophage phagocytosis. The anti-phagocytic signals regulated by anti-phagocytic proteins are termed "don't eat me" signals; these signals include sialic acid-binding immunoglobulin-type lectin-10 (Siglec-10) and the recently revealed CD24 immune checkpoint (ICP). In this study, we demonstrate that targeting a specific glycan on CD24 exhibits the potential to inhibit ICP. Sambucus nigra agglutinin (SNA), a sialic acid-binding lectin, was employed to block CD24 and to enhance phagocytosis in melanoma tumours. In addition, we prepared SNA-conjugated hollow gold-iron oxide nanoparticles for photothermal therapy of tumours. Our findings show that the combination treatment of SNA-conjugated photothermal nanoparticles and near-infrared exposure successfully augments tumour cell phagocytosis both in vitro and in vivo models.
Keywords: Glycan; Immune checkpoint; Immunotherapy; Lectin; Macrophages; Melanoma cancer; Phagocytosis; Photothermal nanoparticles.
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