Immune stimulating activity of an atrophic rhinitis vaccine associated to pegylated chitosan microspheres in vitro

Abstract

It has previously been found that chitosan microspheres are easily aggregated due to their physical and storage instabilities. In this study, to overcome their instability, chitosan was covalently conjugated with poly(ethylene glycol). Pegylated chitosan microspheres were prepared through the ionic gelation process of pegylated chitosan with tripolyphosphate. Bordetella bronchiseptica dermonecrotoxin, major virulence factor of atrophic rhinitis causative agent, was loaded onto pegylated chitosan microspheres for nasal vaccination. Average particle sizes of Bordetella bronchiseptica dermonecrotoxin-loaded pegylated chitosan microspheres were 5.47 µm. Microspheres obtained from pegylated chitosan microspheres were physically more stable than those from chitosan microspheres, and Bordetella bronchiseptica dermonecrotoxin-loaded pegylated chitosan microspheres released more Bordetella bronchiseptica dermonecrotoxin than Bordetella bronchiseptica dermonecrotoxin-loaded chitosan microspheres in vitro. Macrophage RAW264.7 cells stimulated with Bordetella bronchiseptica dermonecrotoxin-loaded pegylated chitosan microspheres gradually secreted tumor necrosis factor and nitric oxide, suggesting that pegylated chitosan microspheres are very promising vaccine delivery systems.