Comparison of the adverse events associated with MF59-adjuvanted and non-adjuvanted H1N1 vaccines in healthy young male Korean soldiers

[Adjuvants of influenza vaccines: new possibilities of using sulphated polysaccharides from marine brown algae.]

The review article presents the characteristics of the main adjuvant groups (mineral salts of aluminum, synthetic squalenebased adjuvants - MF59 and AS03, CpG-oligodeoxynucleotides, virosomes, polyoxidonium, sovidone) included in the licensed influenza vaccine. The main mechanisms of adjuvant action, advantages and disadvantages of these adjuvants are shown. The vaccines adjuvants in the phase of experimental studies and clinical trials (ISCOMs, Advax™, chitosan) are described too. Particular attention is paid to sulfated polysaccharides (fucoidans) from marine brown algae as vaccine adjuvants. Numerous results of their application in compositions of experimental vaccines are presented. The prospects of sulfated polysaccharides using in the design of influenza vaccines are estimated. These prospects are determined by high biocompatibility, low toxicity and good tolerance of the human body to fucoidans, as well as mechanisms of their adjuvant activity. Sulfated polysaccharides are agonists of toll-like receptors of innate immunity cells and powerful inducers of the cellular and humoral immune response, which is important for the development of influenza vaccines. The review is based on the information presented in the bibliographic and abstract databases of scientific publications, search engines and publishers: RSCI, Web of Science, Scopus, MEDLINE, Google Scholar, PubMed, Springer Nature, Elsevier and others.

The Sulfated Polysaccharides of Brown Algae and Products of Their Enzymatic Transformation as Potential Vaccine Adjuvants

The review is devoted to critical analysis of literature data, deal with effects and mechanisms of action of sulfated polysaccharides (PSs) – fucoidans from brown algae and products of their enzymatic transformation as potential adjuvants for enhancement of anti-infective and antitumor immune response. Numerous experimental data indicate that sulfated PSs demonstrate properties of vaccine adjuvants. Application perspectiveness of fucoidans as vaccine adjuvants is defined by their high biocompatibility, low-toxicity, safety and good tolerance by macroorganism, and also mechanisms of their immunomodulatory action. In particular, fucoidans are agonists of receptors of innate immunity and strong inducers of cellular and humoral immune response. At presenting the data of structural - functional interrelations, attention focused to the defining role of degree of sulfation, uronic acids and polyphenols contents, and also molecular mass in actions of fucoidans to innate and adaptive immunity cells. Insufficiency of literary data on studying of correlation of structure – physicochemical characteristics with adjuvanticities of the sulfated PSs, and also the problem of standardization of their active fractions are noted. Special attention is paid to the analysis of immunomodulatory and adjuvant activity of fucoidan oligosaccharides. Presented here results of experimental trial indicate that, despite the difficulties due to preparation of highly purified structurally characterized fractions and complex structure of fucoidans, these substances can be used as safe and effective adjuvants in vaccines against various pathogens including viruses, and also in antitumor vaccines.

Hydroxypropyl-β-cyclodextrin spikes local inflammation that induces Th2 cell and T follicular helper cell responses to the coadministered antigen

Cyclodextrins are commonly used as a safe excipient to enhance the solubility and bioavailability of hydrophobic pharmaceutical agents. Their efficacies and mechanisms as drug-delivery systems have been investigated for decades, but their immunological properties have not been examined. In this study, we reprofiled hydroxypropyl-β-cyclodextrin (HP-β-CD) as a vaccine adjuvant and found that it acts as a potent and unique adjuvant. HP-β-CD triggered the innate immune response at the injection site, was trapped by MARCO(+) macrophages, increased Ag uptake by dendritic cells, and facilitated the generation of T follicular helper cells in the draining lymph nodes. It significantly enhanced Ag-specific Th2 and IgG Ab responses as potently as did the conventional adjuvant, aluminum salt (alum), whereas its ability to induce Ag-specific IgE was less than that of alum. At the injection site, HP-β-CD induced the temporary release of host dsDNA, a damage-associated molecular pattern. DNase-treated mice, MyD88-deficient mice, and TBK1-deficient mice showed significantly reduced Ab responses after immunization with this adjuvant. Finally, we demonstrated that HP-β-CD-adjuvanted influenza hemagglutinin split vaccine protected against a lethal challenge with a clinically isolated pandemic H1N1 influenza virus, and the adjuvant effect of HP-β-CD was demonstrated in cynomolgus macaques. Our results suggest that HP-β-CD acts as a potent MyD88- and TBK1-dependent T follicular helper cell adjuvant and is readily applicable to various vaccines.