Specific and Efficient Uptake of Surfactant-Free Poly(Lactic Acid) Nanovaccine Vehicles by Mucosal Dendritic Cells in Adult Zebrafish after Bath Immersion.

Julien Rességuier,Emilie Delaune,Dominique Le Guellec,Bernard Verrier,Pierre Boudinot,Jean-Pierre Levraud,Anne-Line Coolen

doi:10.3389/fimmu.2017.00190

Abstract

Activation of mucosal immunity is a key milestone for next-generation vaccine development. Biocompatible polymer-based nanoparticles (NPs) are promising vectors and adjuvants for mucosal vaccination. However, their in vivo uptake by mucosae and their biodistribution in antigen-presenting cells (APCs) need to be better understood to optimize mucosal nanovaccine designs. Here, we assessed if APCs are efficiently targeted in a spontaneous manner by surfactant-free poly(lactic acid) nanoparticles (PLA-NPs) after mucosal administration. Combining histology and flow imaging approaches, we describe and quantify the mucosal uptake of 200 nm PLA-NPs in adult zebrafish. Following bath administration, PLA-NPs penetrated and crossed epithelial barriers from all exposed mucosae. In mucosae, PLA-NPs accumulated in APCs, which were identified as dendritic cells (DCs), macrophages, and IgZ+ B cells in gills and skin. PLA-NP uptake by phagocytes was specific to these cell types, as PLA-NPs were not detected in neutrophils. Importantly, quantitative analyses in gills revealed that DCs take up PLA-NPs with specifically high efficiency. This study shows that surfactant-free PLA-NPs, which display optimal biocompatibility, can spontaneously target DCs with high efficiency in vivo following mucosal administration, and highlights PLA-NPs as powerful platforms for mucosal vaccine delivery in the medical and veterinary fields, and particularly in aquaculture.

Highlights

Mucosae represent the first defensive barriers of the organism against most pathogens
Our results suggest that active targeting strategies are not necessarily required for efficient uptake of polymeric NPs by mucosal dendritic cells (DCs), and further highlight the potential of poly(lactic acid co-glycolic acid) (PLGA)- and poly(lactic acid) nanoparticles (PLA-NPs) as mucosal vaccine vehicles for applications in aquaculture
Poly(lactic acid) nanoparticles were produced by nanoprecipitation, a single step process whereby acetone-dissolved PLA is precipitated into a swirling aqueous phase of water and ethanol, in absence of surfactant

Summary

Introduction

Mucosae represent the first defensive barriers of the organism against most pathogens. PLA- and PLGA-NPs constitute versatile vectors for adsorbing and/or encapsulating antigenic peptides and immunostimulant drugs [8, 9]. They have been shown to induce immune responses against various model antigens following parenteral administration in mammals [2, 8]. Their mucosal administration has revealed their ability to cross mucosal barriers, reach some APCs, and elicit mucosal immune responses [6, 10,11,12]. We analyze if polymeric NPs efficiently cross fish mucosal barriers and reach APCs in vivo, using surfactant-free 200 nm poly(lactic acid) nanoparticles (PLA-NPs) as a model. Because NPs generally become quickly coated by proteins and factors present in biological media [14], this model is likely representative of a variety of NPs which surface is functionalized using targeting or antigenic proteins

Methods

Results

Discussion

Conclusion