Development of Alginate/Chitosan Microparticles for Dust Mite Allergen

Purpose: To develop chitosan/alginate microparticles for the mucosal delivery of allergen from dust mite ( Dermatophagoides pteronyssinus ). Methods: Chitosan/alginate microparticles were prepared by ionotropic gelation. The effects of polymer content, crosslinking agent, and preparation method on the physicochemical characteristics of the microparticles as well as their in vitro cytotoxicity were investigated. Results: The microparticles were small (1 -17 µm) and spherical in shape. The highest allergen content (0.30 ± 0.07 mg/g) was obtained with 2.5 % initial allergen loading in chitosan-triphosphate (CS-TPP) microparticles. Sustained allergen release (approx. 50 % over 24 h) was observed from alginate-coated chitosan microparticles. Allergen incorporation method and initial drug-loading could be varied to obtain optimum particle size with high allergen-loading and sustained release. The cytotoxicity of various microparticle formulations did not differ significantly (p > 0.05 ), as cell viability values were close to 100 %. Conclusion: This study indicates that alginate and alginate-coated chitosan microparticles are safe and can be further developed for mucosal allergen delivery

Ovalbumin lipid core peptide vaccines and their CD4+ and CD8+ T cell responses

The lipid core peptide (LCP) system has successfully been used in development of peptide-based vaccines against cancer and infectious diseases (such as group A streptococcal infection). CD8 T cells are important targets for vaccines, however developing a vaccine that activates long-lasting immunity has proven challenging. The ability of LCP vaccines to activate antigen-specific CD8 and/or CD4 T cell responses was tested using compounds that contained two or four copies of OVA and/or OVA peptides conjugated to LCP, which are recognised by OTI (CD8 specific) and OTII (CD4 specific) T cells, respectively. The LCP-ovalbumin vaccines developed in this study were synthesised in 30% yields and showed no significant haemolytic effect on red blood cells (below 4% haemolysis when tested with compounds at up to 100μM concentrations). Promising in vivo data in mice suggested that this LCP-ovalbumin vaccine system could act as a novel and potent vehicle for the stimulation of robust antigen-specific CD8 T cell responses

Oral Methylated N-Aryl Chitosan Derivatives for Inducing Immune Responses to Ovalbumin

Purpose: To investigate different structures of modified chitosan containing different chain lengths and aromatic moieties for vaccine delivery capacity. Methods: The characteristics of the modified chitosan, namely, methylated N-(4-N,Ndimethylaminobenzyl) chitosan (TM-Bz-CS), methylated N-(4-N,N-dimethylaminocinnamyl) chitosan (TM-CM-CS) and methylated N-(4-pyridinylmethyl) chitosan (TM-Py-CS), with Eqiva degree (equivalent degree) were studied by in vitro absorption enhancement on the transepithelial electrical resistance (TEER) in Caco-2 cell monolayers as well as by in vivo adjuvant activity against ovalbumin (OVA), a model antigen, via oral administration to BALB/c mice. Results: At the same concentration and pH (0.1 mg/ml, pH 7.4), TM65CM50CS exhibited the highest in vitro enhancing paracellular permeability and also the highest in vivo adjuvant activity following oral administration to mice. OVA-specific serum immunoglobulin G (IgG) antibody levels of mice that received OVA in TM65CM50CS were significantly (p < 0.05) higher than those that received OVA in TM65CS, TM56Bz42CS and TM53Py40CS. On the other hand, TM65CS and TM56Bz42CS exhibited in vitro enhancing paracellular permeability but showed no immune responses, while TM53Py40CS failed to enhance paracellular permeability and did not elicit immune responses as well. Conclusion: This study demonstrates that addition of hydrophobic moiety (dimethylaminocinnamyl) to CS backbone can increase both its absorption enhancing property and adjuvant activity. The chemical structure and the positive charge location play an important role for binding affinity, absorption enhancement and immune responses