Browsing by Author "Amaral, Rita"
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- Cellular uptake of BCG-loaded chitosan microparticles and in vivo evaluation of immune response following intranasal immunisationPublication . Caetano, Liliana Aranha; Figueiredo, Lara; Amaral, Rita; Almeida, António José; Gonçalves, Lídia Maria DiogoAttenuated Mycobacterium bovis bacillus Calmette-Guérin (BCG) is the only currently available vaccine against tuberculosis. It is highly effective in pre-exposure immunisation against TB in children when administered by subcutaneous route to newborns. However, it does not provide permanent protection in adults. In this work, polymeric chitosan-alginate microparticles have been evaluated as potential nasal delivery systems and mucosal adjuvants for live attenuated BCG. Chitosan (CS) has been employed as adjuvant and mucosal permeation-enhancer, and, together with alginate (ALG), as additive to enhance BCG-loaded microparticles (MPs) cellular uptake in a human monocyte cell line, by particle surface modification. The most suitable particles were used for vaccine formulation and evaluation of immune response following intranasal immunisation of BALB/c mice.
- Chitosan nanoparticles for enhanced immune response and delivery of multi-epitope helicobacter pylori vaccines in a BALB/c mouse modelPublication . Amaral, Rita; Concha, Tomás ; Vítor, Jorge; Almeida, António J.; Calado, Cecília; Diogo Gonçalves, Lídia MariaHelicobacter pylori is the leading cause of chronic gastritis, peptic ulcer, gastric adenocarcinoma, and mucosal-associated lymphoma. Due to the emerging problems with antibiotic treatment against H. pylori in clinical practice, H. pylori vaccination has gained more interest. Oral immunization is considered a promising approach for preventing initial colonization of this bacterium in the gastrointestinal tract, establishing a first line of defense at gastric mucosal surfaces. Chitosan nanoparticles can be exploited effectively for oral vaccine delivery due to their stability, simplicity of target accessibility, and beneficial mucoadhesive and immunogenic properties. Methods: In this study, new multi-epitope pDNA- and recombinant protein-based vaccines incorporating multiple H. pylori antigens were produced and encapsulated in chitosan nanoparticles for oral and intramuscular administration. The induced immune response was assessed through the levels of antigen-specific IgGs, secreted mucosal SIgA, and cytokines (IL-2, IL-10, and IFN-γ) in immunized BALB/C mice. Results: Intramuscular administration of both pDNA and recombinant protein-based vaccines efficiently stimulated the production of specific IgG2a and IgG1, which was supported by cytokines levels. Oral immunizations with either pDNA or recombinant protein vaccines revealed high SIgA levels, suggesting effective gastric mucosal immunization, contrasting with intramuscular immunizations, which did not induce SIgA. Conclusions: These findings indicate that both pDNA and recombinant protein vaccines encapsulated into chitosan nanoparticles are promising candidates for eradicating H. pylori and mitigating associated gastric diseases in humans.
- Chitosan-alginate microparticulate delivery system for an alternative route of administration of BCG vaccinePublication . Caetano, Liliana Aranha; Amaral, Rita; Figueiredo, Lara; Almeida, António J.; Gonçalves, Lídia M.Immunisation against M. tuberculosis with current available BCG vaccine lacks efficacy in preventing adult pulmonary tuberculosis. Targeting nasal mucosa is an attractive option for a more effective immunization. The delivery of BCG via the intranasal route involves overcoming barriers such as crossing the physical barrier imposed by the mucus layer and ciliar remotion, cellular uptake and intracellular trafficking by antigen presenting cells. Due to its biodegradable, immunogenic and mucoadhesive properties, chitosan particulate delivery systems can act both as vaccine carrier and adjuvant, improving the elicited immune response. In this study, different combinations of Chitosan/Alginate/TPP microparticles with BCG were produced as vaccine systems. The developed microparticle system successfully modulates BCG surface physicochemical properties and promotes effective intracellular uptake by human macrophage cell lines Preliminary immune responses were evaluated after s.c. and intranasal immunisation of BALB/c mice. BCG vaccination successfully stimulated the segregation of IgG2a and IgG1, where intranasal immunisation with chitosan/alginate particulate system efficiently elicited a more equilibrated cellular/humoral immune response.