DAMP-Inducing Adjuvant and PAMP Adjuvants Parallelly Enhance Protective Type-2 and Type-1 Immune Responses to Influenza Split Vaccination

Abstract

Recently, it was reported that 2-hydroxypropyl-β-cyclodextrin (HP-β-CyD), a common pharmaceutical additive, can act as a vaccine adjuvant to enhance protective type-2 immunogenicity to co-administered seasonal influenza split vaccine by inducing host-derived damage-associated molecular patterns (DAMPs). However, like most other DAMP-inducing adjuvants such as aluminum hydroxide (Alum), HP-β-CyD may not be sufficient for the induction of protective type-1 (cellular) immune responses, thereby leaving room for improvement. Here, we demonstrate that a combination of HP-β-CyD with a humanized TLR9 agonist, K3 CpG-ODN, a potent pathogen-associated molecular pattern (PAMP), enhanced the protective efficacy of the co-administered influenza split vaccine by inducing antigen-specific type-2 and type-1 immune responses, respectively. Moreover, substantial antigen-specific IgE induction by HP-β-CyD, which can cause an allergic response to immunized antigen was completely suppressed by the addition of K3 CpG-ODN. Furthermore, HP-β-CyD- and K3 CpG-ODN-adjuvanted influenza split vaccination protected the mice against lethal challenge with high doses of heterologous influenza virus, which could not be protected against by single adjuvant vaccines. Further experiments using gene deficient mice revealed the unique immunological mechanism of action in vivo, where type-2 and type-1 immune responses enhanced by the combined adjuvants were dependent on TBK1 and TLR9, respectively, indicating their parallel signaling pathways. Finally, the analysis of immune responses in the draining lymph node suggested that HP-β-CyD promotes the uptake of K3 CpG-ODN by plasmacytoid dendritic cells and B cells, which may contributes to the activation of these cells and enhanced production of IgG2c. Taken together, the results above may offer potential clinical applications for the combination of DAMP-inducing adjuvant and PAMP adjuvant to improve vaccine immunogenicity and efficacy by enhancing both type-2 and type-1 immune responses in a parallel manner.

Murine Cross-Reactive Nonneutralizing Polyclonal IgG1 Antibodies Induced by Influenza Vaccine Inhibit the Cross-Protective Effect of IgG2 against Heterologous Virus in Mice

“…Consistent with previous reports (17,18), we showed that CpG ODN, as an adjuvant, has the potential to protect against heterologous virus challenge (Fig. 3c to f).…”

State‐of‐the‐art in marketed adjuvants and formulations in Allergen Immunotherapy: A position paper of the European Academy of Allergy and Clinical Immunology (EAACI)

“…Since it is the oldest adjuvant in AIT, most facts, figures and toxicity studies are available for Al(OH) 3 . Mechanisms involved include both a depot effect (ie slow release of the allergen, formulation of the allergen as particles to target antigen‐presenting cells (APCs)) as well as interaction with the innate immune system: for example by stimulating the release of damage‐associated molecular patterns (DAMPs), by activating inflammatory DCs or by metabolic reprogramming DCs, while the previously reported dependence from inflammasome activation recently was disputed . More than 90% of all registered AIT products contain Al(OH) 3 in which the European Pharmacopoiea limits the aluminium content to 1.25 mg per parenteral dose .…”

Use of DAMPs and SAMPs as Therapeutic Targets or Therapeutics: A Note of Caution

“…However, one has to realize that-according to current knowledgecell death leads to release of large amounts of other DAMPs as well, which all mediate adjuvanticity. Thus, it is not a surprise that the ongoing development of novel vaccines intend to incorporate the combination of DAMP-inducing adjuvants and PAMP adjuvants [72].…”