The Carbomer-Lecithin Adjuvant Adjuplex Has Potent Immunoactivating Properties and Elicits Protective Adaptive Immunity against Influenza Virus Challenge in Mice

Abstract

The continued discovery and development of adjuvants for vaccine formulation are important to safely increase potency and/or reduce the antigen doses of existing vaccines and tailor the adaptive immune response to newly developed vaccines. Adjuplex is a novel adjuvant platform based on a purified lecithin and carbomer homopolymer. Here, we analyzed the adjuvant activity of Adjuplex in mice for the soluble hemagglutinin (HA) glycoprotein of influenza A virus. The titration of Adjuplex revealed an optimal dose of 1% for immunogenicity, eliciting high titers of HA-specific IgG but inducing no significant weight loss. At this dose, Adjuplex completely protected mice from an otherwise lethal influenza virus challenge and was at least as effective as the adjuvants monophosphoryl lipid A (MPL) and alum in preventing disease. Adjuplex elicited balanced Th1-/Th2-type immune responses with accompanying cytokines and triggered antigen-specific CD8+ T-cell proliferation. The use of the peritoneal inflammation model revealed that Adjuplex recruited dendritic cells (DCs), monocytes, and neutrophils in the context of innate cytokine and chemokine secretion. Adjuplex neither triggered classical maturation of DCs nor activated a pathogen recognition receptor (PRR)-expressing NF-κB reporter cell line, suggesting a mechanism of action different from that reported for classical pathogen-associated molecular pattern (PAMP)-activated innate immunity. Taken together, these data reveal Adjuplex to be a potent and well-tolerated adjuvant with application for subunit vaccines.

Surfactin inducing mitochondria-dependent ROS to activate MAPKs, NF-κB and inflammasomes in macrophages for adjuvant activity

“…For example, TLR agonists such as CpG DNA motifs can activate MAPKs and NF-κB, following lead to secretion of inflammatory mediators, expression of costimulatory ligands and major histocompatibility complex (MHC) molecules, ultimately enhance host humoral and cellular immune response3521. In this study, SFN activated NF-κB nuclear translocation that was obviously inhibited by the mitochondria-dependent ROS inhibitor.…”

“…Several types of inflammasomes ( e.g. NLRP1, NLRP3, IPAF and AIM2) have been described, each containing a specific danger sensor that mediates recognition of a distinct stimulus or a set of stimuli, including ATP, monosodium urate crystals, the adjuvant alum, as well as various bacterial products45. One event required for inflammasome activation is the generation of reactive oxygen species (ROS), as most known inflammasome stimuli trigger ROS generation and treatment with various ROS scavengers blocks inflammasome activation in response to the agonists26.…”

Effective Respiratory CD8 T-Cell Immunity to Influenza Virus Induced by Intranasal Carbomer-Lecithin-Adjuvanted Non-replicating Vaccines

“…[39–44]. Here, using the tractable chicken ovalbumin (OVA) antigen model, we investigated whether ADJ (confirmed to be endotoxin-free) can elicit antigen-specific CD4 and CD8 T cell responses.…”

“…Recent studies on the immune-stimulating properties of ADJ found evidence that ADJ did not induce TLR or NLR signaling in vitro. [68] This does not preclude a role for these signaling pathways in the various interactions underlying the generation of CTL responses in vivo, therefore we repeated our SQ vaccine experiments in MyD88-deficient mice. Virtually all TLR signaling except TLR-3 is abolished in these mice, enabling us to evaluate the role of TLRs in CTL activation and primary responses.…”

“…[39] Here we report that intramuscular, subcutaneous, and intranasal administration of ADJ-adjuvanted non-replicating antigens generated robust antigen-specific CTL responses in mice. Systemic CTL memory was induced regardless of whether mice were vaccinated via subcutaneous, intramuscular or intranasal routes, however, only intranasal vaccination provided protection against influenza viral challenge, and correlated with an enhancement of CD103 + CD69 + CXCR3 + T RM and airway memory T cells in the lung.…”