Cpg boosts peptide-based oral immunotherapy in mice with peanut allergy

Effective therapies for peanut allergy (PA) remain limited. Cytosine-phosphate-guanine oligodeoxynucleotides (CpG ODN) have emerged as promising adjuvants for allergen-specific immunotherapy (AIT). This study aimed to evaluate whether a liposomal delivery system co-encapsulating peanut extract and CpG enhances therapeutic efficacy in a murine PA model and to elucidate the underlying immunoregulatory mechanisms.

A murine PA model was established using peanut extract. Liposomes were formulated to carry peanut extract alone (LipP), CpG alone (LipC), both (LipCP), or were empty (LipE). PA mice received daily gavage of these formulations for two weeks. Clinical symptoms, antibody profiles, intestinal mediator release, and regulatory immune cell populations were assessed.

PA mice exhibited severe anaphylaxis, including a 6.0-fold increase in diarrhea incidence (Cohen's d = 8.21, 95% CI: 5.14-11.28) and a 2.3 °C median core temperature decrease (Cohen's d = 7.94, 95% CI: 4.89-10.99) compared to naive controls (NC). LipCP treatment substantially reduced PA severity: diarrhea incidence decreased by 89% (Cohen's d = 7.86, 95% CI: 4.78-10.94), core temperature reduction was abolished, serum IgE decreased by 78% (Cohen's d = 6.58, 95% CI: 3.85-9.31), and IgG2a/IgG2c levels were restored. LipCP also suppressed intestinal mast cell and eosinophil activation and increased intestinal B10 cell frequency by 3.1-fold (Cohen's d = 6.27, 95% CI: 3.64-8.90) and Tr1 cell frequency by 4.2-fold (Cohen's d = 7.15, 95% CI: 4.21-10.09). In contrast, LipP, LipC, or LipE showed only modest, non-significant effects.

Liposomal co-delivery of peanut extract and CpG effectively suppresses peanut allergy in mice by restoring B10 cell and Tr1 cell-mediated immune tolerance. This approach warrants further investigation for clinical translation.