Identification of Targeting Peptides for Mucosal Delivery in Sheep and Mice

Abstract

In this study we identified and characterized a novel cyclic peptide that facilitates the rapid transportation of conjugated molecules across the epithelial layer of the small intestine. The peptide was initially selected from phage display libraries using a large animal experimental model which employed consecutive in vitro and in vivo panning. The procedure was designed to enrich for peptides that facilitated transcytosis across the intestinal epithelium into the intestinal afferent lymphatic system. A small set of peptides was repeatedly isolated using this selection method, 2 however the cyclic nonamer CTANSSAQC, 13C dominated. The activity of the putative targeting peptide C13 was then verified using a mouse model. These experiments showed that the 13C peptide as well as macromolecules conjugated to it were rapidly transported across the intestinal mucosa into distinct subsets of epithelial cells and CD11+ cells located in the lamina propria and Peyer's Patches. Significant amounts of intact protein could be delivered into the systemic circulation after rectal and nasal application. Thus, peptide 13C is regarded as an attractive carrier candidate for mucosal delivery of large molecules. The preferential targeting to distinct intestinal cells may be utilized to deliver active biological drugs for the effective control of diseases of the gut.

Facilitated Peptide Transport via the Mucosal Epithelium: Impact on Tolerance Induction

“…Microscopic analysis revealed that the fluorochrome-labeled 13C transporter is taken up while the scrambled control peptide largely remains in the lumen of the large intestine, as already shown previously for the small intestine (4). Uptake is first observed in a subset of epithelial cells that have the morphological features of goblet cells, notably in the small intestine (4), but the conjugate also becomes detectable in mucosal CD11c + cells, which mainly consist of DCs (Figure 3).…”

“…The 13C peptide, a nine amino acid long cyclic peptide facilitated mucosal uptake of coupled molecules by, as of yet, unknown mechanisms (4). We here studied the impact of this strategy on vaccination efficacy and tolerance induction in the DO11.10/OVA323-339 peptide (pOVA) model.…”

“…Uptake is first observed in a subset of epithelial cells that have the morphological features of goblet cells, notably in the small intestine (4), but the conjugate also becomes detectable in mucosal CD11c + cells, which mainly consist of DCs (Figure 3). The proportion of the conjugates remaining in DCs and the proportion being transported via lymph to the systemic circulation could not been determined with the present technique.…”

“…We have previously demonstrated that the 13C peptide is also able to carry large proteins in intact form through the mucosal barrier (4). It will be interesting to test whether tolerization with intact proteins using this targeting pathway leads to different results compared with high-dose oral protein application, where most likely only peptides reach the circulation.…”

“…We recently identified the 13C peptide that increases uptake and transcytosis of peptides and proteins upon mucosal administration (4). The study demonstrated that labeled 13C peptide as well as peptide or protein bound to it is rapidly taken up by subsets of epithelial cells in the intestinal mucosa.…”