Influence of surface charge of PLGA particles of recombinant hepatitis B surface antigen in enhancing systemic and mucosal immune responses.
ABSTRACT This study investigates the efficacy of surface-modified microspheres of hepatitis B surface antigen (HBsAg) in eliciting systemic and mucosal immune responses. Positively charged poly(D,L-lactic-co-glycolic acid) microspheres were prepared by a double-emulsion solvent-evaporation method with cationic agents--stearylamine and polyethylenimine--in the external aqueous phase. Formulations were characterized for morphology, size, density, aerodynamic diameter, entrapment efficiency and in vitro drug-release profile. Immunization was performed after pulmonary administration of the formulations to female Sprague-Dawley rats and the immune response was monitored by measuring IgG levels in serum and secretory (sIgA) levels in salivary, vaginal and bronchoalveolar lavage fluids. The cell-mediated immune response was studied by measuring cytokine levels in spleen homogenates, and a cytotoxicity study was performed with Calu-3 cell line. The aerodynamic diameter of the particles was within the respirable range, with the exception of stearylamine-modified particles. Zeta potential values moved from negative (-6.76 mV) for unmodified formulations to positive (+0.515 mV) for polyethylenimine-modified particles. Compared to unmodified formulations, polyethylenimine-based formulations showed continuous release of antigen over a period of 28-42 days and increased levels of IgG in serum and sIgA in salivary, vaginal and bronchoalveolar lavage. Further, cytokine levels-interferon gamma and interleukin-2-were increased in spleen homogenates. The viability of Calu-3 cells was not adversely affected by the microparticles. In summation, this study establishes that positive surface charges on poly(D,L-lactic-co-glycolic acid) particles containing HBsAg enhances both the systemic and mucosal immune response upon immunization via the respiratory route.
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ABSTRACT: The development of novel immune adjuvants is emerging as a significant area of vaccine delivery based on the continued necessity to amplify immune responses to a wide array of new antigens that are poorly immunogenic. This article specifically focuses on the application of nanoparticles and microparticles as vaccine adjuvants. Many investigators are in agreement that the size of the particles is crucial to their adjuvant activities. However, reports on correlating the size of particle-based adjuvants and the resultant immune responses have been conflicting, with investigators on both sides of the fence with impressive data in support of the effectiveness of particles with small sizes (submicron) over those with larger sizes (micron) and vice versa, while other investigators reported data that showed submicron- and micron-sized particles are effective to the same degree as immune adjuvants. We have generated a list of biological, immunological and, more importantly, vaccine formulation parameters that may have contributed to the inconsistency from different studies and made recommendations on future studies attempting to correlate the size of particulate adjuvants and the immune responses induced. The information gathered could lead to strategies to optimize the performance of nano-microparticles as immune adjuvants.Expert Review of Vaccines 09/2010; 9(9):1095-107. · 4.22 Impact Factor
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ABSTRACT: Cross-presentation is the key process in stimulation of cytotoxic T lymphocyte (CTL) immune response in eliminating many infectious diseases and tumors. Previous studies have shown that surface modification of poly(D,L-lactic-co-glycolic acid) (PLGA) particles with polycations enhanced their adjuvant ability resulting in a strong antibody response to the encapsulated antigen. However, the in vitro cross-presentation by protamine-coated PLGA nanoparticles (NPs) has not been addressed yet. In this study, a model antigen ovalbumin (OVA) was encapsulated into PLGA nanoparticles, with (OVA-NPs/protamine) or without protamine coating (OVA-NPs). These nanoparticles were then used to stimulate murine bone marrow-derived dendritic cells (BMDCs). Flow cytometry analysis revealed an increase in endocytosis of protamine-coated PLGA nanoparticles by BMDCs at 37°C. Compared with OVA-NPs-treated BMDCs, stimulation with OVA-NPs/protamine led to significantly upregulation of CD80, CD86, and CD83, increased secretion of IL-12p70, and decreased production of IL-4 by BMDCs. Furthermore, OVA-NPs/protamine-treated BMDCs also showed an enhanced cross-presentation to B3Z T cell hybridoma in vitro. Transmission electron microscopy (TEM) study showed that protamine-coated PLGA nanoparticles escaped from lysosomes through the interaction with lysosomal membrane. These results demonstrated that protamine-coated PLGA nanoparticles could enhance the cross-presentation of encapsulated exogenous antigen by facilitating antigen uptake and lysosomal escape, suggesting the feasibility to be a potent adjuvant for cellular vaccines.Journal of Biomedical Materials Research Part A 01/2011; 96(1):142-9. · 2.83 Impact Factor
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ABSTRACT: Abstract Technological advances in drug discovery have resulted in increasing number of molecules including proteins and peptides as drug candidates. However, how to deliver drugs with satisfactory therapeutic effect, minimal side effects and increased patient compliance is a question posted before researchers, especially for those drugs with poor solubility, large molecular weight or instability. Microfabrication technology, polymer science and bioconjugate chemistry combine to address these problems and generate a number of novel engineered drug delivery systems. Injection routes usually have poor patient compliance due to their invasive nature and potential safety concerns over needle reuse. The alternative non-invasive routes, such as oral, mucosal (pulmonary, nasal, ocular, buccal, rectal, vaginal), and transdermal drug delivery have thus attracted many attentions. Here, we review the applications of the novel engineered systems for oral, mucosal and transdermal drug delivery.Journal of Drug Targeting 08/2013; 21(7):611-29. · 2.77 Impact Factor