Nasal nanovaccines.

Nasal administration of vaccines is convenient for the potential stimulation of mucosal and systemic immune protection. Moreover the easy accessibility of the intranasal route renders it optimal for pandemic vaccination. Nanoparticles have been identified as ideal delivery systems and adjuvants for vaccine application. Heterogeneous protocols have been used for animal studies. This complicates the understanding of the formulation influence on the immune response and the comparison of the different nanoparticles approaches developed. Moreover anatomical and immunological differences between rodents and humans provide an additional hurdle in the rational development of nasal nanovaccines. This review will give a comprehensive expertise of the state of the art in nasal nanovaccines in animals and humans focusing on the nanomaterial used.

Mechanisms allowing protein delivery in nasal mucosa using NPL nanoparticles.

The intranasal administration of proteins using nanoparticles is a promising approach for several applications, especially for mucosal vaccines. Delivery of protein within the epithelial barrier is a key point to elicit an immune response and nano-carrier has to show no toxicity. The aim of this work was to elucidate the interactions of cationic porous nanoparticles loaded with protein delivery for antigen delivery in the nose. We investigated the loading, the cellular delivery and the epithelial transcytosis of proteins associated to these nanoparticles containing an anionic lipid in their core (NPL). NPL were highly endocytosed by airway epithelial cells and significantly improved the protein delivery into the cell. In vitro transcytosis studies showed that NPL did not modify the in vitro epithelial permeability suggesting no toxicity of these carriers. Moreover protein and NPL did not translocate the epithelial barrier. In vivo studies demonstrated that NPL prolonged the nasal residence time of the protein and no NPL were found beyond the epithelial barrier in vivo, precluding a negative side effect. All together these results establish the NPL as a bio-eliminable and optimal vaccine carrier.

Characterization and phase behaviour of phospholipid bilayers adsorbed on spherical polysaccharidic nanoparticles.

In this paper a new drug carrier, the Light-biovector, is described. These biovectors are composed of a neutral, anionic or cationic polysaccharidic core surrounded by phospholipids. They can be prepared with high yield and in a nearly pure form as determined by density analysis on sucrose gradients. These particles showed great stability with no sedimentation being observed after more than one year of storage. Physicochemical studies carried out with dipalmitoylphosphatidylcholine and dipalmitoylphosphatidylcholine/dipalmitoylphosphatidylglycerol mixtures showed that in Light-biovectors, the lipids are organized in bilayer surrounding the polysaccharidic core. In presence of a neutral polysaccharidic core, the gel to liquid phase transition temperature Tm of DPPC was only slightly affected as compared to liposomal dispersions of the lipid. In contrast, for cationic and anionic Light-biovectors, the Tm of the lipids was affected by the electric charge born by the polysaccharidic core, indicating that electrostatic interactions contribute to the organization of the lipid bilayer in these systems. It was also found that the association of anionic membrane to anionic polysaccharidic cores and the association of cationic membrane to cationic polysaccharidic cores was possible.

A combination of interleukin-2 and 60 nm cationic supramolecular biovectors for the treatment of established tumours by subcutaneous or intranasal administration.

The Supramolecular Biovector (SMBV) KY is a drug delivery nanocarrier which consists of a discretely sized, ionically charged, cross-linked polysaccharide core surrounded by a lipid membrane. We used the non-immunogenic spontaneous mammary adenocarcinoma TS/A tumour to test the efficacy on tumour growth of low (10(4) IU) or ultra-low (10(3) IU) doses of interleukin-2 (IL-2) adsorbed to these 60 nm cationic synthetic particles. In comparison with the progressive growth of TS/A cells in syngeneic mice, KY/IL-2 particles coinjected with TS/A cells or administered at a distance from the tumour, inhibited tumour growth while free IL-2, even at 10-100 times the dose used in the KY/IL-2 formulations, had no effect. Studies performed on implanted tumours (treatment at day 6 (D6)) showed that KY/IL-2 administered subcutaneously (s.c.) at five sites distant from the tumour (10(3) IL-2 IU per site) induced rejection of the implanted tumours. Six out of 10 mice were cured while the other four had residual tumours only. In the same experiment, free IL-2 induced only tumoral growth reduction. Protection induced by KY/IL-2 administered s.c. at five sites involved recruitment of a CD8(+) T cell response since nu/nu mice and CD8-depleted mice did not reject the tumours. Mice cured were protected significantly to completely against a rechallenge with TS/A tumour cells, and a systemic tumour-specific CTL activity was induced. Finally, we showed that repeated intranasal (i.n.) administration of KY/IL-2 (low-dose) also led to complete regression of pre-established tumours and partial protection from tumour rechallenge. We therefore suggest that, in contrast to free IL-2, a KY/IL-2 formulation could be used as a systemic immunostimulant leading to the eradication of non-immunogenic, established tumours.

Characterization of a benzyl-phenoxy-ethanamine binding protein in Trypanosoma equiperdum and the possible relation between binding affinity and trypanocidal activity.

A new family of benzyl-phenoxy-ethanamine derivatives has been assayed for trypanocidal activity. Using tritiated morpholino-benzyl-phenoxy-ethanamine as a probe, it is shown that this ligand is able to bind specifically to a protein contained in extracts of Trypanosoma equiperdum. The binding is saturable and of high affinity (KD = 4 nM: Bmax = 200 fmol (mg protein)-1). The in vitro activities of the investigated compounds against this parasite correlate with their affinities to the putative binding site. Moreover, using an azido functionalized morpholino-benzyl-phenoxyethanamine as photoprobe a major M(r) = 40,000 protein was specifically revealed by sodium dodecyl sulphate polyacrylamide gel electrophoresis. This molecular weight corresponds with the previously observed value determined for the antioestrogen binding site protein of rat liver which has been shown to specifically bind antioestrogens of the triphenylethylene family and phenoxyethanamine derivatives.

Production of homogeneous basic fibroblast growth factor by specific enzymatic hydrolysis of larger microheterogeneous molecular forms.

The 146-amino acid form of basic fibroblast growth factor (bFGF) was expressed in Escherichia coli and purified by a two step process including ion exchange and heparin-Sepharose chromatographies. However, the resulting protein consisted of a mixture of 146- and 145-amino acid forms, indicating that, besides the initial methionine, also the following residue (proline) was removed from the N-terminus. The same phenomenon was observed when the 155-amino acid form, which is biologically equivalent to the shorter one, was expressed in E. coli. Taking into account the previously known data concerning the possible mechanism of cleavage of the extended forms of bFGF in vivo, we developed an efficient enzymatic process that allows the production of an homogeneous 146-amino acid form from recombinant NH2-end extended forms. This process takes advantage of the protecting effect that heparin exerts on bFGF. Accordingly, when bFGF, complexed to heparin, is treated with pepsin A, an aspartic protease with a broad specificity, only the Leu9-Pro10 peptide bond is cleaved generating the 146-amino acid form. Quantitative yields of this reaction are also achieved when bFGF is bound to a heparin-Sepharose column, allowing the integration of this enzymatic step directly during purification of the recombinant extended forms of bFGF.

Fluosol 43 intravascular persistence in mice measured by 19F nmr.

Quantitative determination of the intravascular persistence of F-tri-n-butylamine (FC 43 as Fluosol 43) in mice was carried out using 19F nmr spectroscopy. The method allows the direct study of whole blood, neither separation nor extraction of the sample being required. Accuracy (reproducibility) is better than +/- 3%, and is comparable to that of the gas chromatographic (gc) method. The sensitivity of detection is less than that of the gc method but is sufficient for this biological study. It was observed that the intravascular elimination of F-tri-n-butylamine follows a non-linear kinetic and becomes faster about 40 h after the injection. This phenomenon may be explained by the size-increase of the FC 43 droplets in the emulsion. Indeed, at about 40 h after injection, the level of Pluronic F-68 in the bloodstream was no longer sufficient to maintain the stability of the FC-43 droplets. They therefore tended to coalesce forming larger droplets that were phagocytosed more rapidly by the histiocytes of the reticuloendothelial system.

Development of innovative paclitaxel-loaded small PLGA nanoparticles: study of their antiproliferative activity and their molecular interactions on prostatic cancer cells.

Taxanes, including paclitaxel, are anti-cancer drugs approved for the treatment of prostate cancer but which have limited clinical application due to their hydrophobicity, their low therapeutic index and the emergence of chemoresistance. These side effects may be avoided through the use of new drug delivery systems such as nanoparticles, and paclitaxel-loaded PLGA nanoparticles up to 200 nm in size have shown encouraging results. As it is known that size affects the tissular penetration and distribution of tumors via the enhanced permeability and retention effect, so nanoparticles smaller than 100 nm are potentially interesting vehicles for improving paclitaxel delivery and efficacy. In this work, new paclitaxel-loaded small PLGA nanoparticles, between 49 nm and 95 nm in size and with positive or negative surface charges, were prepared without detergent. They were stable in the presence of serum, and HPLC showed that high paclitaxel loading and stability were achieved. Intracellular uptake of these nanoparticles was studied in PC3 cells by flow cytometry. Confocal studies confirmed a high tubulin destructuration at very low dose with these nanoparticles. This study suggests that both positively and negatively charged paclitaxel-loaded small PLGA nanoparticles deliver this drug into PC3 cells, and that this nanoparticle mode of delivery highly improves paclitaxel efficiency by up to two log-increase. These results also highlight the importance of small nanoparticles for drug delivery in cancer applications and are extremely promising for in vivo studies.

Formulation and characterization of polyphenol-loaded lipid nanocapsules.

The purpose of this study was to design and characterize two flavonoid-loaded lipid nanocapsules (LNC) by applying the phase inversion process, and to enhance their apparent solubility and/or the stability. The flavonoid-loaded LNC were characterized by particle size, encapsulation efficiency, drug leakage rates, stability and spectroscopic studies. It was observed that quercetin-loaded LNC30 (3%) and LNC60 (2%) carried a particle size of 30.3 and 55.1 nm, respectively and significant higher entrapment efficiency. Encapsulation of quercetin (QC) in LNC enabled us to increase its apparent aqueous solubility by a factor of 100. And in view of calculations and results, it seems most probable that QC is arranged at this LNC interface between the oil phase and the hydrophilic polyethylene glycol moieties of the surfactant. In addition, colloidal suspensions proved to be stable in term of encapsulation for at least 10 weeks and QC was not oxidised. With simple chemical modification of (-)-epigallocatechin-3-gallate or (-)-EGCG, it was possible to reach very high encapsulation rates (95%). Thus we obtained stable colloidal suspensions of (-)-EGCG in water over 4 weeks while free (-)-EGCG solubilised in water exhibited 100% degradation within 4h. The initial problems (solubility and stability) of these flavonoids were resolved thanks to drug-loaded LNC.

Effect of high-intensity interval training and detraining on extra VO2 and on the VO2 slow component.

To examine the effect of 6-week of high-intensity interval training (HIT) and of 6-week of detraining on the VO2/Work Rate (WR) relationship and on the slow component of VO2, nine young male adults performed on cycle ergometer, before, after training and after detraining, an incremental exercise (IE), and a 6-min constant work rate exercise (CWRE) above the first ventilatory threshold (VT1). For each IE, the slope and the intercept of the VO2/WR relationship were calculated with linear regression using data before VT1. The difference between VO2max measured and VO2max expected using the pre-VT1 slope was calculated (extra VO2). The difference between VO2 at 6th min and VO2 at 3rd min during CWRE (DeltaVO2(6'-3')) was also determined. HIT induced significant improvement of most of the aerobic fitness parameters while most of these parameters returned to their pre-training level after detraining. Extra VO2 during IE was reduced after training (130 +/- 100 vs. -29 +/- 175 ml min(-1), P = 0.04) and was not altered after detraining compared to post-training. DeltaVO2(6'-3') during CWRE was unchanged by training and by detraining. We found a significant correlation (r2 = 0.575, P = 0.02) between extra VO2 and DeltaVO2(6'-3') before training. These results show that an alteration of extra VO2 can occur without any change in the VO2 slow component, suggesting a possible dissociation of the two phenomena. Moreover, the fact that extra VO2 did not change after detraining could indicate that this improvement may remain after the loss of other adaptations.

Effect of prior heavy exercise on muscle deoxygenation kinetics at the onset of subsequent heavy exercise.

This study examines the effect of prior heavy exercise on muscle deoxygenation kinetics at the onset of heavy-intensity cycling exercise. Ten young male adults (20 +/- 2 years) performed two repetitions of step transitions (6 min) from 35 W to heavy-intensity exercise preceded by either no warm-up or by a heavy-intensity exercise. VO2 was measured breath-by-breath, and muscle deoxygenation (HHb) and total hemoglobin (Hb(tot)) were monitored continuously by near-infrared spectroscopy. We used a two-exponential model to describe the VO2 kinetics and a mono-exponential model for the HHb kinetic. The parameters of the phase II VO2 kinetics (TD1 VO2, tau1 VO2 and A1 VO2) were unaffected by prior heavy exercise, while some parameters of local muscle deoxygenation kinetics were significantly faster (TD HHb: 7 +/- 2 vs. 5 +/- 2 s; P < 0.001, MRT HHb: 20 +/- 3 vs. 15+/- 4 s; P < 0.05). Blood lactate, heart rate and Hb(tot) values were significantly higher before the second bout of heavy exercise. These results collectively suggest that the prior heavy exercise probably increased muscle O2 availability and improved O2 utilization at the onset of a subsequent bout of heavy exercise.

Effect of prior exercise on the VO2/work rate relationship during incremental exercise and constant work rate exercise.

The disproportionate increase in VO2 ("extra VO2) reported at elevated intensity during incremental exercise (IE) might result from the same physiological mechanisms as the VO2 slow component observed during heavy constant work rate exercise (CWRE). Moreover, it has been demonstrated that prior heavy exercise can diminish the VO2 slow component. The aim of this study was to evaluate whether prior heavy exercise also alters the "extra VO2" during IE. Ten trained sprinters performed three tests on a cycle ergometer: Test 1 was an IE; Test 2 consisted of six minutes of a CWRE (90% of VO2max) followed by six minutes at 35 W and by an IE and Test 3 was composed of two CWRE of six minutes separated by six minutes of exercise at 35 W. For each IE, the slope and the intercept of the VO2/work rate relationship were calculated by linear regression using data before the first Ventilatory Threshold (pre-VT1 slope). The difference between VO2max measured and VO2max expected using the pre-LT slope was calculated (deltaVO2). We also calculated the difference between VO2 at min five and VO2 at min three during CWRE of Test 3 (deltaVO2(5' - 3')). VO2max was significantly higher than VO2exp during IE of Test 1 and Test 2. deltaVO2 during IE did not differ between Test 1 and Test 2 (+ 259 +/- 229 ml x min(-1) vs. + 222 +/- 221 ml x min(-1)). During Test 3, six subjects achieved five minutes of exercise during the second CWRE and deltaVO2(5' - 3') was significantly decreased during the second CWRE (338 +/- 65 ml x min(-1) vs. 68 +/- 98 ml x min(-1), n = 6). These results demonstrate that the amplitude of the "extra VO2"during IE was not affected by prior exercise, whereas the slow component of VO2 evaluated by deltaVO2(5' - 3') during CWRE was lowered. This implies that prior exercise does not have the same effect on the slow component of VO2 and on the "extra VO2". Therefore we were unable to demonstrate a relationship between the VO2 slow component and the extra-VO2 phenomenon during IE.

The stereoselective enzymatic synthesis of 9-beta-D-2'-deoxyribofuranosyl 1-deazapurine.

The transfer of 2-deoxyribose from thymidine to 1-deazapurine which is catalysed by N-deoxyribosyl transferases from Lactobacillus leichmanii occurs in high yield. This is a very stereoselective process and only one product, 9-beta-D-2'-deoxyribofuranosyl 1-deazapurine, is formed. Nmr spectroscopy, and in particular, nuclear Overhauser enhancement experiments, confirm that the 2-deoxyribose moiety is bound to N-9 rather than N-7 and that the glycosidic link has the beta-configuration.

Design and antileishmanial activity of amphotericin B-loaded stable ionic amphiphile biovector formulations.

A new delivery system, Ionic Amphiphilic Biovector (ABV), comprised of anionic lipids (dipalmitoyl phosphatidyl glycerol) included in a cationic cross-linked polysaccharide matrix was used as a reservoir for amphotericin B (AmB). Two ABV formulations exhibited an in vitro and in vivo efficacy similar to commercial AmBisome against Leishmania donovani-infected mice. The higher stability of these ABV formulations indicates their potential for further development and applications.

Proofs of the structure of lipid coated nanoparticles (SMBV) used as drug carriers.

PURPOSE: Supramolecular Biovectors (SMBV) consist of cross-linked cationic nanoparticles surrounded by a lipid membrane. The purpose was to study the structure of the lipid membrane and to characterise its interaction with the nanoparticles in order to differentiate SMBV from other polymer/lipid associations. METHODS: The interaction of lipids with the nanoparticle surface was studied using zeta potential. Fluorescence Energy Transfer (FET) and Fluorescence Microscopy. SMBV were compared to liposomes and mixtures nanoparticles/liposomes. Finally the structure of SMBV was visualised by Electron Microscopy. RESULTS: Zeta potential measurements showed that lipids on SMBV had a pronounced shielding effect on the surface charge. This was not the case for mixtures of nanoparticles and liposomes. FET experiments confirmed these results indicating that, for SMBV, the lipids are much closer to the nanoparticle surface. SMBV Fluorescence microscopy on model microparticles showed a lipid crown on SMBV that was confirmed by electron microscopy on SMBV nanoparticles. CONCLUSIONS: Results show that in case of SMBV lipids are strongly adsorbed on the polysaccharide core surface probably due to ionic/hydrophobic interactions. The resulting supramolecular structure is a spherical cationic polysaccharide particle surrounded by a phospholipid/cholesterol layer.

Stabilization and enhancement of interleukin-2 in vitro bioactivity by new carriers: supramolecular biovectors.

Human recombinant interleukin-2 can be associated and released from supramolecular biovectors (SMBVs), consisting of particles made of polymerized polysaccharides. The particles are substituted with phosphate residues and contain bound lipid molecules (palmitic acid) buried near their surfaces. The association of IL-2 with SMBVs modifies its in vitro bioactivity. SMBVs prolong the growth of IL-2-dependent cells, enhance IL-2 proliferative activity and restore the activity of impaired IL-2. These properties mainly depend on the presence of lipids linked to the SMBV and on both the degree of acylation and the SMBV: IL-2 ratio. SMBVs are therefore good candidates for the stabilization and enhancement of the biological activity of IL-2.

Evaluation of effect of charge and lipid coating on ability of 60-nm nanoparticles to cross an in vitro model of the blood-brain barrier.

A cell culture model of the blood-brain barrier (BBB) consisting of a coculture of bovine brain capillary endothelial cells and rat astrocytes has been used to examine the ability of 60-nm nanoparticles with different physicochemical characteristics to cross the BBB. Neutral, anionic, and cationic nanoparticles were made from crosslinked malto-dextrins derivatized or not (neutral) with phosphates (anionic), quaternary ammoniums (cationic) ligands. Then, these particles were coated or not with a lipid bilayer made of dipalmitoyl phosphatidyl choline and cholesterol. Lipid coating of ionically charged nanoparticles was able to increase BBB crossing 3- or 4-fold compared with uncoated particles, whereas coating of neutral particles did not significantly alter their permeation characteristics across the endothelial cell monolayer. Lipid-coated nanoparticles were nontoxic toward BBB integrity, and crossed the BBB by transcytosis without any degradation. Furthermore, a 27-fold increase in albumin transport was observed when albumin had previously been loaded in the cationic lipid-coated nanoparticles. The influence of red blood cells was studied; a marked inhibition of the transport was observed, probably due to strong interaction between nanoparticles and red blood cells.

A new family of carriers (biovectors) enhances the immunogenicity of rabies antigens.

Biovectors (BV) are a new family of protein carriers. They are nanoparticles of polymerized polysaccharides substituted with phosphate residues and surrounded by covalently bound lipid molecules (palmitic acid). The effect of BV was tested on the immunogenicity of rabies antigens. Biovectors enhanced the production of antibody induced by both rabies glycoprotein and ribonucleoprotein. Moreover, they enhanced the protective activity of an experimental rabies vaccine composed of inactivated and purified virus. The isotype profile of antibody produced in vivo was not modified when BV were mixed with rabies antigens. To clarify the mechanism of the adjuvant/ immunostimulation effect of BV, two types of approach were used: (1) analysis of the antibody response when antigen and BV were injected separately; (2) determination of the nature of cells involved in the proliferation in vitro of murine splenocytes in the presence of BV. The enhancing effect of BV on antibody production was highest when mixed with antigens. In vitro BV induced the proliferation of B cells. These findings suggest that BV have immunostimulating properties in addition to their probable depot and/or antigen-presentation effect which explain in part their adjuvant activity.

Biovector nanoparticles improve antinociceptive efficacy of nasal morphine.

PURPOSE: We have studied the antinociceptive activity and blood and brain delivery of nasal morphine with or without Biovector nanoparticles in mice. METHODS: A tail flick assay was used to evaluate the antinociceptive activity. The kinetics of morphine were evaluated in blood and brain, using tritiated morphine as tracer. RESULTS: These nanoparticles were shown to increase the duration of the antinociceptive activity of morphine after nasal administration. This effect was not due to an increase of morphine in the blood; and the analgesic activity of morphine in association with nanoparticles was reversed by naloxone. The ED50 value was 33.6+/-15.6 mg/kg for morphine alone and 14.4+/-7.6 mg/kg in presence of nanoparticles. They were only effective at low doses (1.5 to 2.5 microg), a higher or a lower dose had no effect. No interaction was found between nanoparticles and morphine. NaDOC, a permeation enhancer, was unable to improve nasal morphine activity. CONCLUSIONS: These results show the presence of nanoparticles only at a very specific dose increases the antinociceptive activity of nasal morphine in mice. The occurrence of a direct transport of morphine from the nasal mucosa to the brain is discussed.

Combination of human cytomegalovirus recombinant immediate-early protein (IE1) with 80 nm cationic biovectors: protection from proteolysis and potentiation of presentation to CD4+ T-cell clones in vitro.

We have shown in a previous study that the proliferative CD4+ T-cell response to the regulatory immediate-early protein IE1 was a major component of the overall anti viral response in human cytomegalovirus (HCMV) seropositive blood donors. This viral antigen may be valuable in subunit vaccine design, since anti IE1 CD4+ T cells might provide help for production of antibodies and cytotoxic T lymphocytes (CTL) responses, and could take part in the control of viral infection. Preliminary to the elaboration of future vaccine formulations, we developed immunogenic complexes resulting from the combination of a purified recombinant protein derived from the fusion of Escherichia coli glutathione-S-transferase (GST) and a large C-terminal fragment (e4) of IE1, with new 80 nm cationic synthetic particles called Biovectors. We have shown that the antigen GST-e4 was stably complexed to vectors and that, contrary to the soluble form, it was protected from proteolysis in cell culture medium. By confocal microscopy we observed that the synthetic vectors were internalized by lymphoblastoid B cells, providing a significant enhancement of antigen delivery in antigen presenting cells (APC). Indeed, we demonstrated that the previous combination of antigen with particles, significantly enhanced the proliferation of specific CD4+ T-cell clones directed against IE1 in vitro, when either HLA-matched isolated peripheral blood mononuclear cells or EBV transformed B cell lines were used as APC. The relevance of these observations to the use of these new vectors for vaccine design against HCMV is discussed.