Glycosylated Carbonated Apatite Particles for Macrophage-Targeted Delivery of CpG Oligodeoxynucleotides From Streptococcus thermophilus Enhance Immune Activation.

Abstract

Immunostimulatory CpG oligodeoxynucleotides (CpG-ODNs) are potent activators of innate immunity with promising applications in human and veterinary medicine. We previously developed carbonate apatite-based oligonucleotide particles (ODNcaps) for oral delivery, which are efficiently taken up by macrophages in jejunal Peyer's patches. To enhance macrophage-specific targeting, we introduced glycan modifications to ODNcaps, exploiting carbohydrate-binding receptors on macrophages. In this study, glycosylated ODNcaps were synthesized through N-acetylglucosamine (GlcNAc) conjugation and evaluated for cellular uptake and immunostimulatory activity in mouse peritoneal macrophages. Uptake efficiency was quantified using fluorescently labeled CpG-ODNs, and immune activation was assessed by IL-6 mRNA expression and IL-6 secretion. GlcNAc-modified ODNcaps showed markedly higher uptake and induced the strongest IL-6 responses at both transcriptional and protein levels compared with non-glycosylated controls. These results demonstrate that glycosylation is a simple yet effective strategy to improve macrophage targeting and immunostimulation by CpG-ODNs. Beyond murine models, this platform may hold promise for oral or mucosal immune modulation in livestock such as cattle, poultry, and swine, offering a novel approach to enhance antigen-presenting cell activation and strengthen mucosal immunity in animal production.