Mucosal Immunization Through Peptide Specific for GM-1 or M cell

Objectives: Mucosal surface, the most common infection route, is exposed to the harsh environment but is well protected by a layer of tightly joined epithelial cell and mucosal immune system. In mucosal vaccination, this barrier is a hard obstacle for antigen to pass through to reach underlying immune induction machinery. One approach to enhance vaccine delivery across the epithelial barrier is mucosal targeting of antigen to reach mucosal lymphoid tissue such as Peyer's patch containing GM-1 abundant M cell, a specialized antigen uptake cell. Methods: Phage display library was utilized to select peptide ligands binding to GM-1 ganglioside or cultured M cell. Using recombinant EGFP-ligand fusion protein, the role of ligand in mucosal delivery was tested using EGFP with or without ligand motif in culture M cell, in the intestinal loop system ex vivo, and finally in mouse model. Genrations of EGFP-specific antibodies after oral administration of EGFP with or without ligand motif were compared to confirm the roles of ligands in EGFP-specific immune induction. T cell proliferation assay and cytokine analysis were also conducted. Results: The recombinant fusion proteins bind to GM-1 ganglioside or cultured M cell and more significantly bind to Peyer's patch ex vivo and in vivo. Also we observed that some of ligands fusion protein transport across mucosal surface of the Peyer's patch in ex vivo intestinal loop model. In mouse model, these ligand fusion proteins induced mucosal IgA response after oral administration and also high systemic immune response yielding EGFP-specific serum IgG. Interestingly, one M-cell specifc ligand bound to M cell and induced IgA production early in oral administration of EGFP-ligand fusion protein but thereafter declined EGFP-specific IgA production. Conclusion: Our study suggests that GM-1 or M cell specific peptide ligands could function as adjuvants for mucosal targeting and vaccine development.