Novel adjuvant Alum-TLR7 significantly potentiates immune response to glycoconjugate vaccines.

Although glycoconjugate vaccines are generally very efficacious, there is still a need to improve their efficacy, especially in eliciting a strong primary antibody response. We have recently described a new type of vaccine adjuvant based on a TLR7 agonist adsorbed to alum (Alum-TLR7), which is highly efficacious at enhancing immunogenicity of protein based vaccines. Since no adjuvant has been shown to potentiate the immune response to glycoconjugate vaccines in humans, we investigated if Alum-TLR7 is able to improve immunogenicity of this class of vaccines. We found that in a mouse model Alum-TLR7 greatly improved potency of a CRM197-MenC vaccine increasing anti-MenC antibody titers and serum bactericidal activity (SBA) against MenC compared to alum adjuvanted vaccine, especially with a low dose of antigen and already after a single immunization. Alum-TLR7 also drives antibody response towards Th1 isotypes. This adjuvant was also able to increase immunogenicity of all polysaccharides of a multicomponent glycoconjugate vaccine CRM197-MenACWY. Furthermore, we found that Alum-TLR7 increases anti-polysaccharide immune response even in the presence of a prior immune response against the carrier protein. Finally, we demonstrate that Alum-TLR7 adjuvant effect requires a functional TLR7. Taken together, our data support the use of Alum-TLR7 as adjuvant for glycoconjugate vaccines.

Positive Contribution of Adjuvanted Influenza Vaccines to the Resolution of Bacterial Superinfections.

BACKGROUND: Most preclinical studies assess vaccine effectiveness in single-pathogen infection models. This is unrealistic given that humans are continuously exposed to different commensals and pathogens in sequential and mixed infections. Accordingly, complications from secondary bacterial infection are a leading cause of influenza-associated morbidity and mortality. New vaccination strategies are needed to control infections on simultaneous fronts. METHODS: We compared different anti-influenza vaccines for their protective potential in a model of viral infection with bacterial superinfection. Mice were immunized with H1N1/A/California/7/2009 subunit vaccines, formulated with different adjuvants inducing either T-helper type 1 (Th1) (MF59 plus CpG)-, Th1/2 (MF59)-, or Th17 (LTK63)-prone immune responses and were sequentially challenged with mouse-adapted influenza virus H1N1/A/Puerto Rico/8/1934 and Staphylococcus aureus USA300, a clonotype emerging as a leading contributor in postinfluenza pneumonia in humans. RESULTS: Unadjuvanted vaccine controlled single viral infection, yet mice had considerable morbidity from viral disease and bacterial superinfection. In contrast, all adjuvanted vaccines efficiently protected mice in both conditions. Interestingly, the Th1-inducing formulation was superior to Th1/2 or Th17 inducers. CONCLUSIONS: Our studies should help us better understand how differential immunity to influenza skews immune responses toward coinfecting bacteria and discover novel modes to prevent bacterial superinfections in the lungs of persons with influenza.

Novel injectable and in situ cross-linkable hydrogels of dextran methacrylate and scleroglucan derivatives: preparation and characterization.

In this paper mixtures of two biocompatible polymers, dextran methacrylate (DEX-MA) with different molecular weights and scleroglucan (Scl), in its native form and as carboxymethyl derivative (Scl-CM), were tested as injectable and in situ cross-linkable systems. Rheological and texture analyses were carried out to better investigate the behavior of this kind of matrices. The combination of these polymers is able to assure adequate mechanical properties, suitable for biomedical applications. In addition swelling studies and in vitro release studies of three different biomolecules were also carried out.

Novel pH-sensitive physical hydrogels of carboxymethyl scleroglucan.

A carboxymethyl derivative of scleroglucan (Scl-CM) with derivatization degree 300 ± 10 was synthesized and characterized by Fourier transform infrared spectroscopy, potentiometer titration, mucus adhesion studies, and rheological measurements. Rheological measurements showed the ability of the polymer to undergo sol-gel transitions even in the absence of salts. Swelling experiments, performed on freeze-dried samples in different media, showed good affinity of these hydrogels toward the aqueous media and a pH-sensitive behavior. Four nonsteroidal anti-inflammatory drugs (NSAIDs) were loaded into the physical hydrogels obtained from 2.0% (w/v) solutions of the polymer. The results of the release studies carried out in conditions simulating the gastrointestinal tract showed that the new hydrogels could be suggested for the modified oral delivery of NSAIDs, particularly damaging for the gastric mucosa. In vivo studies proved the biocompatibility of the matrix and the absence of any gastric damage for administration of ulcerogenic doses of diclofenac loaded into the hydrogel (DIC/Scl-CM-300). Moreover, DIC/Scl-CM-300 was found to be effective in peripheral analgesia.

Physical carboxymethylscleroglucan/calcium ion hydrogels as modified drug delivery systems in topical formulations.

A carboxymethyl derivative of scleroglucan (Scl-CM) with a 65+/-5% carboxylic group degree of derivatization (DD) was recently synthesized and characterized. Aqueous solutions of the polymer underwent to a sharp transition toward a gel like behaviour in the presence of divalent ions such as Ca(+2). Physical hydrogels with different Scl-CM/Ca(+2) ratios were prepared and characterized for their rheological behaviour. Their potential as drug delivery systems was also evaluated. To this end three non steroidal anti-inflammatory drugs (NSAIDs) were loaded into the hydrogels obtained with 2% w/v solution of Scl-CM and 0.05 and 0.1 M CaCl(2). The release rate of the drugs was critically related to the salt concentration. By an appropriate combination of the hydrogels prepared using different amounts of salt, it was possible to obtain a system able to release diclofenac with zero-order kinetics. Primary skin irritation tests showed a good biocompatibility of the new polymer, as well as of its hydrogels. These results suggest a potential of the new hydrogels for the development of modified delivery systems in topical formulations.

Influence of the formulation components on the properties of the system SLN-dextran hydrogel for the modified release of drugs.

A system composed by solid lipid nanoparticles (SLN) entrapped into a chemical hydrogel of dextran was recently proposed for the controlled release of lipophilic drugs in oral formulations. This study reports now an extension of such study focused on the investigation of how the nature and the amount of the formulation components are able to modify the properties of the system. In particular the concentration of the two surfactants used for the nanosuspension stabilization, the nature of the lipid phase used for the nanoparticles preparation, as well as the concentration and the derivatization degree of the polymer employed for the gel preparation were investigated. The effects of these variables on the physicochemical properties of the nanoparticles and/or on the release profiles of the model drug (S)-(+)-2-(4-isobutylphenyl)-propionic acid (ibuprofen) were reported and discussed. Rheological experiments on samples of SLN, dextran hydrogel, and SLN-dextran hydrogel were also performed.

pH-sensitive hydrogels of dextran: synthesis, characterization and in vivo studies.

pH-Sensitive hydrogels of dextran were synthesized by photochemical cross-linking reaction of methacrylate dextran (DEX-MA) at different derivatization degree, functionalized with acidic residues through reaction with phthalic anhydride. The hydrogels were characterized by FT-IR spectra, swelling measurements, experiments of chemical and enzymatic hydrolyses. The swelling data agreed with the formation of networks having pH-sensitive behaviour. This property was confirmed by the morphological examination performed by scanning electron microscopy on samples maintained in media at different pH. (S)-4-Isobutyl-2-phenylpropionic acid (ibuprofen) was loaded into the polymeric matrices. The analysis of the release profiles of the drug from the three networks showed that all the matrices were able to retain ibuprofen during the transit through the stomach, releasing it in a sustained way in the intestinal tract at a rate strictly dependent on the derivatization degree in methacrylic groups. In vivo studies verified the biocompatibility of the materials. Moreover, when the matrix loaded with ibuprofen was administered to rats, it was able to protect them from the ulcerogenic effects of the drug.