Dynamics of APC recruitment at the site of injection following injection of vaccine adjuvants

Abstract

a b s t r a c tVaccines often contain adjuvants to strengthen the response to the vaccine antigen. However, their modes of action at the site of injection (SOI) are poorly understood. Therefore, we assessed the local effects of adjuvant on the innate immune system in mice. We investigated the safe, widely used adjuvants MF59 and aluminum hydroxide (alum), as well as trehalose-6,60 -dibehenate (TDB), Complete Freund's Adjuvant (CFA) and the Toll-Like-Receptor-ligands lipopolysaccharide (LPS) and Pam3CysSerLys4 (Pam 3 CSK 4 ). We assessed muscle immune cell infiltration after adjuvant injection and observed 16 h post immunization (hpi) an increased influx with CFA, MF59 and TDB, but not with alum, LPS or Pam 3 CSK 4 . An elevated influx with the latter three became visible only 72 hpi. Contribution of granulocytes, macrophages and dendritic cells to the influx differed per adjuvant and in time. Adjuvants generally induced a local pro-inflammatory micro-milieu that was transient except for CFA and TDB. The gene expression of CXCL-1, CCL-2 and CCL-5, involved in recruitment of immune cells, varied per adjuvant and corresponded grossly with the observed influx of granulocytes and monocytes/ macrophages. Muscles injected with CFA or MF59 (when co-injected with peptide) resulted in APC ex vivo capable to induce proliferation of peptide-specific T-cells. By adding in vitro an excess of peptide to the APC/T cell co-cultures, we observed an adjuvant-enhanced co-stimulation or antigen presentation by APC after CFA-but not MF59-injection. After TDB-injection this effect was observed only at 72 hpi, but not 24 hpi. Thus the cellular influx profile and the local cytokine and chemokine micro-milieu in the muscle were strongly influenced by the type of adjuvant. Additionally, the capacity of muscle APC to load and present antigen was affected by the adjuvant. These findings may assist the development of novel adjuvanted vaccines in a more rational manner.

Respiratory Syncytial Virus F Subunit Vaccine With AS02 Adjuvant Elicits Balanced, Robust Humoral and Cellular Immunity in BALB/c Mice

“…MPL in AS02 may also activate the NF-κB signaling pathway (GO Enrichment “I-κB kinase/NF-κB signaling,” P -value 0.028, data not shown) through TLR-4 receptors on immune cells, such as macrophages or dendritic cells at the intramuscular injection site ( 52 ). Cytokines such as interleukin-1 can promote monocyte and immature DC recruitment to the injection-site, and mobilize these monocytes into APCs ( 53 – 55 ).…”

A Canine-Directed Chimeric Multi-Epitope Vaccine Induced Protective Immune Responses in BALB/c Mice Infected with Leishmania infantum

“…The results showed that the mice vaccinated with LiChimera developed antigen-specific cellular and humoral immune responses, which were significantly enhanced when LiChimera was given along with Addavax, a commercial oil-in-water emulsion analogue of the MF59 adjuvant. The main effect of that emulsion was the effective recruitment of APCs to the site of injection followed by their migration to draining lymph nodes for antigens presentation to the CD4 + T cells [ 72 , 73 ]. Importantly, we found that bone marrow-derived macrophages from the LiChimera/Addavax-vaccinated mice presented enhanced leishmanicidal capacity as assessed by a decreased percentage of infected cells, which was attributed to increased levels of NO production.…”

Bystander activation of irrelevant CD4+ T cells following antigen-specific vaccination occurs in the presence and absence of adjuvant

“…The experimental adjuvant CFA is known to induce strong inflammatory responses [33,36] including the induction of autoimmune arthritis in rats [37,38] and mice [39], and therefore not suitable for human vaccines [33]. It was included as the compound to secure maximal immune activation and indeed we were able to show that unrelated transferred CD4 + T cells were activated and proliferating after CFA prime injection as well as after CFA/IFA prime-boost injection (Fig 3) indicating bystander activation.…”