Sequential Barrier Navigation by Yeast β-Glucan-Engineered Liposomal Nanovaccines Potentiates Oral Melanoma Immunotherapy.

PURPOSE: Orally delivered protein antigens face gastrointestinal degradation and inefficient transport through mucus, across the intestinal epithelium, and into antigen-presenting cells (APCs). To address these barriers, we developed YGB@OVA/PBA-C-LIPs, an ovalbumin (OVA)-loaded cationic liposomal nanovaccine coated with yeast β-glucan (YGB) and functionalized with phenylboronic acid (PBA).

METHODS

We characterized the physicochemical properties of YGB@OVA/PBA-C-LIPs and evaluated their mucus and epithelial transport, macrophage uptake, OVA cross-presentation, and immune activation in vitro. Laminarin competition was used to assess β-glucan-sensitive uptake. Gastrointestinal residence, immune responses, antitumor activity, and tolerability were examined after oral administration to B16-OVA-bearing mice.

RESULTS

YGB@OVA/PBA-C-LIPs averaged 127.5 ± 0.8 nm in diameter and had an OVA encapsulation efficiency of 83.17 ± 1.98%, with no marked size increase over 12 days at 4 °C. They improved transport through a simulated mucus layer and across the Caco-2/Raji B model and increased RAW264.7 macrophage uptake; laminarin attenuated this advantage, supporting a β-glucan-sensitive component of uptake. The formulation also increased surface CD80 and H-2Kb-SIINFEKL levels in DC2.4 cells and IFN-γ release in DC2.4-splenocyte co-cultures. After a single oral dose, the Cy7-labeled formulation remained detectable in the abdomen at 72 h. Repeated dosing reduced tumor weight by 75.0% versus untreated tumor-bearing controls (0.36 ± 0.11 versus 1.44 ± 0.23 g) and increased serum OVA-specific IgG reactivity to 3.8 times the control value. Major-organ histology showed no evident abnormalities.

CONCLUSION

The YGB/PBA dual-functionalized formulation combined gastrointestinal protection and mucosal transport with enhanced antigen presentation by APCs, improving immune responses and tumor control in the B16-OVA model. Validation with clinically relevant tumor antigens is needed to establish broader therapeutic relevance.