Oral Vaccination Through Peyer's Patches: Update on Particle Uptake

Background: Oral immunization has numerous advantages over parenteral administrations. In addition to ease administration, more effective pathogen elimination on the mucosa before spreading into the blood circulation, constitutes the main benefit. This is particularly true for pathogens that enter the body through the oral route. On the other hand, it is the most challenging administration route for peptides, proteins and recombinant antigens due to gastrointestinal (GI) tract, numerous barriers including the harsh environment and the inherent weak immunogenicity. In addition to the adjuvant properties, polymeric particles arise as the most promising strategy to overcome poor antigen bioavailability/ stability upon oral administration. The Peyer's patches have been considered an important structure of the gut associate lymphoid tissue (GALT) for the initiation of the immune response towards particulate oral antigens. Objective: The transport mechanism of both, nano and microparticles across intestinal mucosa, particularly throughout Peyer's patches, is discussed in this review. Conclusion: We provide a short and concise update (last decade) focused on the importance of particle physicochemical properties, M-cell ligands and size-dependent transport and intracellular fate concerning Peyer's patches targeted oral vaccination.