The effect of antigen encapsulation in chitosan particles on uptake, activation and presentation by antigen presenting cells

Abstract

Particle-based vaccine delivery systems are under exploration to enhance antigen-specific immunity against safe but poorly immunogenic polypeptide antigens. Chitosan is a promising biomaterial for antigen encapsulation and delivery due to its ability to form nano- and microparticles in mild aqueous conditions thus preserving the antigenicity of loaded polypeptides. In this study, the influence of chitosan encapsulation on antigen uptake, activation and presentation by antigen presenting cells (APCs) is explored. Fluorescein isothiocyanate-labeled bovine serum albumin (FITC-BSA) and ovalbumin (OVA) were used as model protein antigens and encapsulated in chitosan particles via precipitation-coacervation at loading efficiencies >89%. Formulation conditions were manipulated to create antigen-encapsulated chitosan particles (AgCPs) with discrete nominal sizes (300nm, 1µm, and 3µm). Uptake of AgCPs by dendritic cells and macrophages was found to be dependent on particle size, antigen concentration and exposure time. Flow cytometry analysis revealed that uptake of AgCPs enhanced upregulation of surface activation markers on APCs and increased the release of pro-inflammatory cytokines. Lastly, antigen-specific T cells exhibited higher proliferative responses when stimulated with APCs activated with AgCPs versus soluble antigen. These data suggest that encapsulation of antigens in chitosan particles enhances uptake, activation and presentation by APCs.

Pulmonary dry powder vaccine of pneumococcal antigen loaded nanoparticles

“…In addition, the decrease in surface charge could be due to the protein molecules orientation adopted on the surface of the NPs exposing only a small part of the protein. Similar results have been reported by Koppolu et al and Gordon et al (Gordon et al, 2008;Koppolu and Zaharoff, 2013).…”

“…In addition, the size, charge, shape and site of delivery all affect the extent of DCs uptake and thus the immune response generated (Joshi et al, 2013), with NPs < 500 nm showing higher uptake and activation of DCs and inducing stronger immune responses (Foged et al, 2005;Joshi et al, 2013;Koppolu and Zaharoff, 2013). Here, to substantiate our claims of effective uptake by DCs upon producing NPs of size ~ 300 nm, their uptake in JAWS II DC cell type was visualized using confocal microscopy.…”

“…Research is now focused on delivering antigens via particulate carriers where the antigen can be associated with the particles acting as delivery systems with the added benefit of augmenting the generated immune response upon uptake by antigen presenting cells (APCs) (O'Hagan, 2001). In addition, particulate antigens are known to generate a stronger immune response compared to soluble antigen (Koppolu and Zaharoff, 2013). As such, research has been focused on using polymeric nanoparticles (NPs) as delivery vehicles for antigen delivery (Kong et al, 2013;Koppolu and Zaharoff, 2013).…”

“…In addition, particulate antigens are known to generate a stronger immune response compared to soluble antigen (Koppolu and Zaharoff, 2013). As such, research has been focused on using polymeric nanoparticles (NPs) as delivery vehicles for antigen delivery (Kong et al, 2013;Koppolu and Zaharoff, 2013). Lately, it has also been shown by different groups that polymeric particles have enhanced the immunogenicity of PspA (Anish et al, 2014;Haughney et al, 2013;Kong et al, 2013).…”

Harnessing Nanoparticles for Immune Modulation

“…Furthermore, positively charged antigen-loaded NPs are significantly more effective at stimulating Th1 responses after either intradermal or mucosal (pulmonary) inoculation, whereas anionic particles stimulate T and B cell responses poorly under similar conditions [22,23]. The ability of cationic particles to stimulate Th1 responses has been associated with preferential DC uptake of such particles and the propensity of cationic particles to regulate positive costimulatory molecules [24]. However, cationic NPs may also alter mitochondrial and endoplasmic reticulum function, triggering the production of reactive oxygen species and proinflammatory cytokines, as well as cell death [25][26][27].…”