Browsing by Author "Figueiredo, Lara"
Now showing 1 - 7 of 7
Results Per Page
Sort Options
- Alginate-chitosan particulate delivery systems for mucosal immunization against tuberculosisPublication . Caetano, Liliana Aranha; Figueiredo, Lara; Almeida, António J.; Gonçalves, Lídia M. D.Although vaccination is still the most cost-effective strategy for tuberculosis control, there is an urgent need for an improved vaccine. Current BCG vaccine lacks efficacy in preventing adult pulmonary tuberculosis, the most prevalent form of the disease. Targeting nasal mucosa, Mycobacterium tuberculosis infection site, will allow a simpler, less prone to risk of infection and more effective immunization against disease. Due to its biodegradable, immunogenic and mucoadhesive properties, chitosan particulate delivery systems can act both as carrier and as adjuvant, improving the elicited immune response. In this study, BCG was encapsulated in alginate and chitosan microparticles, via a mild ionotropic gelation procedure with sodium tripolyphosphate as a counterion. The particulate system developed shows effective modulation of BCG surface physicochemical properties, suitable for mucosal immunization. Intracellular uptake was confirmed by effective transfection of human macrophage cell lines.
- BCG-loaded chitosan microparticles: interaction with macrophages and preliminary in vivo studiesPublication . Caetano, Liliana Aranha; Figueiredo, Lara; Almeida, António J.; Gonçalves, L. M.The aim of this study was to develop a novel BCG-loaded chitosan vaccine with high association efficiency which can afford efficient interaction with APC and elicit local and Th1-type-specific immune response after intranasal administration. Chitosan-suspended BCG and BCG-loaded chitosan-alginate microparticles were prepared by ionotropic gelation. Interaction with APC was evaluated by fluorescence microscopy using rBCG-GFP. Specific immune responses were evaluated following intranasal immunization of mice. Cellular uptake was approximately two-fold higher for chitosan-suspended BCG. A single dose of BCG-loaded microparticles or chitosan-suspended BCG by intranasal route improved Th1-type response compared with subcutaneous BCG. Chitosan-suspended BCG originated the highest mucosal response in the lungs by the intranasal route. These positive results indicate that the proposed approach of whole live BCG microencapsulation in chitosan-alginate for intranasal immunization was successful in allowing efficient interaction with APC while improving the cellular immune response, which is of interest for local immunization against tuberculosis.
- BCG-loaded chitosan microparticles: interaction with macrophages and preliminary in vivo studiesPublication . Caetano, Liliana Aranha; Figueiredo, Lara; Almeida, António J.; Gonçalves, L. M. D.The aim of this study was to develop a novel BCG-loaded chitosan vaccine with high association efficiency which can afford efficient interaction with APC and elicit local and Th1-type-specific immune response after intranasal administration. Chitosan-suspended BCG and BCG-loaded chitosan-alginate microparticles were prepared by ionotropic gelation. Interaction with APC was evaluated by fluorescence microscopy using rBCG-GFP. Specific immune responses were evaluated following intranasal immunisation of mice. Cellular uptake was approximately two-fold higher for chitosan-suspended BCG. A single dose of BCG-loaded microparticles or chitosan-suspended BCG by intranasal route improved Th1-type response compared with subcutaneous BCG. Chitosan-suspended BCG originated the highest mucosal response in the lungs by intranasal route. These positive results indicate that the proposed approach of whole live BCG microencapsulation in chitosan-alginate for intranasal immunisation was successful in allowing efficient interaction with APC, while improving the cellular immune response, which is of interest for local immunisation against tuberculosis.
- Biodegradable nanoparticles of alginate and chitosan as non-viral DNA oral delivery systemPublication . Gonçalves, Lídia M. D.; Cadete, Ana; Figueiredo, Lara; Calado, Cecília; Almeida, António J.The delivery of nucleic acids via the oral route involves overcoming barriers such as degradation of nucleic acids by low pH in the stomach, enzymatic degradation by DNases in the gut, crossing the physical barrier imposed by the mucus layer, cellular uptake, intracellular trafficking and nuclear uptake. As an oral drug carrier system chitosan nanoparticles are ideal, being mucoadhesive, interacting with the anionic sialic acid residues in mucin. In this study, plasmid DNA expressing a humanized secreted Gaussia Luciferase as reporter gene was encapsulated in alginate and chitosan nanoparticles, via a mild ionotropic gelation procedure with sodium tripolyphosphate as a counterion. The nanoparticle system here developed shows effective transfection of different human gastric epithelial cell lines with distinct cell differention. That was confirmed by the expression of luciferase in the different tested conditions, particularly the amount of encapsulated pGLuc.
- 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-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.
- Protein and DNA nanoparticulate multiantigenic vaccines against H. pylori: In vivo evaluationPublication . Figueiredo, Lara; Calado, Cecília; Almeida, António J.; Gonçalves, Lídia M. D.Immunisation against H. pylori is an attractive option for antibiotic resistance and reinfection situations. Strain genetic heterogeneity, and low immunogenicity of protein antigens and DNA alone are nonetheless obstacles to this approach. We developed multigenic H. pylori DNA-nanoparticle and protein-nanoparticle vaccines based on pathogenic relevance. Six antigens were chosen for the vaccine construction: CagA, VacA, HpaA, UreB, HomB and GroEL. Different combinations of CS/DS and CS/Alg /TPP nanoparticles with DNA and chimeric proteins were produced as vaccine systems. Immune responses were evaluated after i.m. and oral immunisation of BALB/c mice. Oral vaccination successfully stimulated mucosal immunity while i.m. immunisation efficiently elicited a more equilibrated cellular/humoral immune response.