Oral mucosal immunization using glucomannosylated bilosomes.

The present study embarks on the feasibility of GM-bilosomes as a rationally designed vehicle for oral mucosal immunization. Bilosomes containing BSA as a model antigen were found to have vesicle size of 157 +/- 3 nm, PDI of 0.287 +/- 0.045, zeta potential of -21.8 +/- 2.01 mV and entrapment efficiency of 71.3 +/- 4.3%. Bilosomal formulations were freeze dried and entrapped BSA in freeze dried formulations was found to retain its structural and conformational stability as evident by SDS-PAGE and CD analysis. The GM-bilosomes were also found stable in different simulated biological fluids and bile salt solutions of different concentrations. In-vitro drug release revealed that GM-bilosomes were able to sustain drug release up to 24 h. In-vitro cell uptake in RAW 264.7 macrophage cells demonstrated significantly higher uptake of GM-bilosomes in comparison with bilosomes and free antigen. Intestinal uptake studies on excised rat intestinal sections further demonstrated higher uptake of vesicular systems throughout the intestinal region in comparison with free antigen. Significantly higher (p < 0.05) systemic immune response (serum IgG level) was observed in case of GM-bilosomes in comparison with bilosomes and alum adsorbed BSA (BSA-AL) following oral administration. The immune response observed in case of GM-bilosomes was comparable to BSA-AL administered through im route without any significant difference (p > 0.05). More importantly, GM-bilosomes were found capable of inducing mucosal immune response as well as cell mediated immune response which was not induced by im BSA-AL. In conclusion, GM-bilosomes could be considered as promising carrier and adjuvant system for oral mucosal immunization and productively exploited for oral delivery of other candidate antigens.