Poly(anhydride) nanoparticles as adjuvants for mucosal vaccination.

In the last years, many efforts have been directed toward the enhancement of vaccine delivery by using polymeric nanoparticles as adjuvants for mucosal immunization. However, conventional nanoparticles usually display a low capability to target specific sites within the gut and, thus, the elicited immune responses are not as high as necessary to offer the adequate protection to the host. To overcome these drawbacks, one possible strategy can be the association of nanoparticles with compounds involved in the colonization process of microorganisms. In this biomimetic context, two different examples are shown. In both cases, poly(anhydride) nanoparticles were coated with either flagellin from Salmonella Enteritidis or mannosamine. When administered by the oral route both types of ligand-coated nanoparticles induced stronger and more balanced serum titers of IgG2a and IgG1 than control nanoparticles which induced a typical Th2 response. This Th1 response enhancement may be related to the high tropism of both flagellin- and mannosylated-nanoparticles to the ileum and uptake by Peyer's patches rich in antigen presenting cells.

Immunoadjuvant capacity of flagellin and mannosamine-coated poly(anhydride) nanoparticles in oral vaccination.

Bioadhesive poly(anhydride) nanoparticles coated with mannose (M-NP) or Salmonella Enteritidis derived flagellin (F-NP) were designed to be applied in oral vaccination strategies using ovalbumin (OVA) as antigen model. Nanoparticles formulations (OVA-M-NP, OVA-F-NP and control OVA-NP) were characterized and evaluated in BALB/c mice. OVA-M-NP and OVA-F-NP displayed a size of about 300-400 nm and were efficiently coated with the respective ligand, Systemic and mucosal immune responses reported after S.C. and oral administration, indicated that a single dose of OVA-M-NP and OVA-F-NP, elicited higher and balanced systemic specific antibody responses [IgG1 (Th2-response) and IgG2a (Th1-response)] compared to non-coated ones. In addition, oral immunization using OVA-M-NP or OVAF-NP was able to elicit a higher levels of intestinal secretory IgA compared to S.C. In summary, oral immunization by bioadhesive mannosylated or flagellin nanoparticles demonstrated strong long lasting systemic and mucosal immune responses than the respective non-conjugated vectors.

Evaluation of bioadhesive capacity and immunoadjuvant properties of vitamin B(12)-Gantrez nanoparticles.

PURPOSE: To design bioadhesive Gantrez AN (poly[methyl vinyl ether-co-maleic anhydride], PVM/MA) nanoparticles (NP) coated with vitamin B(12) (Vit B(12)), and investigate their application in oral antigen delivery. METHODS: The association of Vit B(12) to Gantrez AN nanoparticles was performed by the direct attachment of reactive Vit B(12) to the surface of the nanoparticles (NPB), or linking to the copolymer chains in dimethylformamide prior to NP formation (NPB-DMF). Nanoparticles were characterized by measuring the size, zeta potential, Vit B(12) association efficacy, and stability of Vit B(12) on the surface of the nanoparticles. In vivo bioadhesion study was performed by the oral administration of fluorescently-labeled nanoparticle formulations to rats. Both systemic and mucosal immune responses were evaluated after oral and subcutaneous immunization with ovalbumin (OVA) containing Vit B(12)-coated nanoparticles. RESULTS: The Vit B(12) nanoparticles displayed homogenous size distribution with a mean diameter of about 200 nm and a negative surface charge. The association efficiency of Vit B(12) to NPB-DMF formulation was about two times higher than to the NPB, showing also a higher surface stability of Vit B(12). The bioadhesion study demonstrated that NPB-DMF had an important tropism to the distal portions of the gut, which was about two and 3.5 times higher than the tropism observed for NPB and control NP, respectively (p < 0.05). Oral administration of OVA-NPB-DMF induced also stronger and more balanced serum anti-OVA titers of IgG2a (Th1) and IgG1 (Th2) compared to control OVA-NP. In addition, oral immunization with OVA-NPB-DMF induced a higher mucosal IgA response than subcutaneous administration. CONCLUSIONS: These results indicate the benefits of bioadhesive Vit B(12)-coated nanoparticles in oral antigen delivery eliciting systemic and mucosal immune response.

Mannose-targeted systems for the delivery of therapeutics.

BACKGROUND: The specific targeting of nanomedicines to mannose receptors, highly expressed in cells of the immune system, performs a useful strategy for improving the efficacy of vaccines and chemotherapy. OBJECTIVE: This review discusses the potential of mannose-targeted drug/antigen delivery systems for vaccination and treatment of diseases localized in macrophages and other antigen-presenting cells. METHODS: The first part of the review describes the characteristics, localization and functions of mannose receptors. The following sections are devoted to the description of different methods used to deliver therapeutic agents, including mannose conjugates and mannosylated carriers or particulates (i.e., liposomes, nanoparticles and niosomes). RESULTS/CONCLUSIONS: A general overview of published reports confirms the effectiveness of mannosylation strategies, although the optimization and full exploitation of mannose-targeted drug delivery systems would require a deeper understanding of the structure-activity relationship. In the near future, these nanomedicines have the potential to treat a number of diseases (including cancer) and improve the quality of life of patients.

Bioadhesive capacity and immunoadjuvant properties of thiamine-coated nanoparticles.

The general aim of this work was to develop polymeric nanoparticle carriers with bioadhesive properties, and to evaluate its adjuvant potential for oral vaccination. Thiamine was used as specific ligand-nanoparticle conjugate (TNP) to target specific sites within the gastrointestinal tract, enterocytes and Peyer's patches. The affinity of nanoparticles to the gut mucosa was studied in orally inoculated rats. In contrast to conventional non-coated nanoparticles (NP), higher levels of TNP were found in the ileum tissue, showing a strong capacity to be captured by Peyer's patches. TNP were characterized by an AUCadh which was found to be three times higher than for control NP. To investigate the adjuvant capacity of TNP, ovalbumin (OVA) was used as standard antigen. Oral immunization of BALB/c mice with OVA-TNP induced stronger serum titers of specific IgG2a and IgG1 and mucosal IgA compared to OVA-NP. This mucosal immune response (IgA) was about 4-titers higher than that elicited by OVA-NP. These results suggest the use of thiamine-coated nanoparticles as particle vectors for oral vaccine and immunotherapy delivery strategies.

Bioadhesive mannosylated nanoparticles for oral drug delivery.

The aim of this work was to design mannosylated Gantrez AN nanoparticles (M-NP) and to describe their gut bioadhesive properties in order to develop a promising carrier for future applications in oral drug delivery. For that purpose, the process of the nanoparticles coating with mannosamine was optimized by the incubation of Gantrez AN nanoparticles with different volumes of mannosamine aqueous solutions at different times. Then, the nanoparticles were characterized by measuring the size, zeta potential, mannosamine content, and concanavalin A (Con A) binding. Furthermore, in vivo quantitative bioadhesion study and kinetic analysis of the bioadhesion curves were performed after oral administration to rats of fluorescently labelled nanoparticles. The selected mannosylated nanoparticles (M-NP1 and M-NP10) were of homogenous sizes (about 300 and 200 nm), negatively charged and successfully coated with 36 and 18 microg mannosamine/mg NP, respectively. In vitro agglutination assay using Con A confirmed the successful coating of nanoparticles with mannosamine. The gut distribution profile of M-NP1 indicated a stronger bioadhesive capacity than M-NP10 and non-mannosylated ones, 1 h post-administration. Interestingly, M-NP1 showed an important ileum tropism where around 20% of the given dose remained adhered. Besides, the kinetic parameters of the bioadhesion profile of M-NP1 indicated their higher bioadhesive capacity with Q(max) and AUC(adh) about 2-times higher than control ones. Moreover, fluorescence microscopy corroborated the stronger interactions of M-NP1 with the normal mucosa and demonstrated a strong uptake of these carriers by Peyer's patches. In conclusion, we propose that mannosylated nanoparticles could be a promising non-live vector for oral delivery strategies.

Salmonella-like bioadhesive nanoparticles.

The aim of this work was to evaluate the bioadhesive potential of a polymeric vector obtained by the association between Gantrez AN nanoparticles and flagella-enriched Salmonella enteritidis extract. Fluorescently labelled nanoparticles (SE-NP) were prepared, after incubation between the polymer and the extract, by a solvent displacement method and cross-linkage with 1,3-diaminopropane. SE-NP displayed a size close to 280 nm and the amount of associated bacterial extract was 18 mug/mg nanoparticle. Flagellin represents more than 80% of the total proteins associated with SE-NP, which was identified by SDS-PAGE and confirmed by Western blotting. Concerning the bioadhesive properties, SE-NP shows an important tropism for the ileum. In fact, about 50% of the given dose of SE-NP was found in this gut region for at least 3 h. Interestingly, the bioadhesive ability of SE-NP correlated well with the described colonisation profile for Salmonella enteritidis. This fact was corroborated by competitive tissue distribution studies. Thus, when SE-NP and Salmonella cells were administered together by the oral route, both the bacteria and the nanoparticles displayed a similar distribution within the intestinal mucosa. However, the ability of SE-NP to be taken up by Peyer's patches appeared to be negatively affected by the presence of the bacteria. Similarly, when SE-NP was administered 30 min before cells, SE-NP were found broadly distributed in Peyer's patches, whereas the bacteria were neither able to adhere to nor penetrate this lymphoid tissue. In summary, SE-NP demonstrated their Salmonella-like gut colonization, which can be a useful vector for oral targeting strategies.