Targeted delivery of chitosan nanoparticles to Peyer's patch using M cell-homing peptide selected by phage display technique.

This study is aimed to develop an efficient oral vaccine carrier which specifically targets the follicle-associated epithelium region of Peyer's patch (PP). M cell-homing peptide was selected by the phase display technique and its targeting efficiency was validated using chitosan nanoparticles (CNs) conjugated with the discovered peptide. A phage clone encoding CKSTHPLSC (CKS9) peptide sequence was selected by analysis of comparative superiority in transcytosis efficacy across the M cell layer in vitro and in vivo among the candidates. CKS9 was chemically conjugated to water-soluble chitosan (WSC) and the CKS9-immobilized chitosan nanoparticles (CKS9-CNs) were prepared by ionic gelation of CKS9-WSC with tripolyphosphate, yielding spherical nanoparticles around 226.2 +/- 41.9 nm. The targeting ability of CKS9-CNs to the M cell and to the PP regions of rat small intestine was investigated by in vitro transcytosis assay and closed ileal loop assay, respectively, and was visualized by fluorescence-microscopy analysis. CKS9-CNs were transported more effectively across the M cell model and accumulated more specifically into PP regions in comparison with CNs, indicating that CKS9 peptide prominently enhanced the targeting and transcytosis ability of CNs to PP regions. These results suggest that the CKS9-CNs could be used as a new carrier for oral vaccine delivery.