TANK-binding kinase-1 delineates innate and adaptive immune responses to DNA vaccines

Abstract

Successful vaccines contain not only protective antigen(s) but also an adjuvant component that triggers innate immune activation and is necessary for their optimal immunogenicity. In the case of DNA vaccines, this consists of plasmid DNA; however, the adjuvant element(s) as well as its intra- and inter-cellular innate immune signalling pathway(s) leading to the encoded antigen-specific T- and B-cell responses remain unclear. Here we demonstrate in vivo that TANK-binding kinase 1 (TBK1), a non-canonical IkappaB kinase, mediates the adjuvant effect of DNA vaccines and is essential for its immunogenicity in mice. Plasmid-DNA-activated, TBK1-dependent signalling and the resultant type-I interferon receptor-mediated signalling was required for induction of antigen-specific B and T cells, which occurred even in the absence of innate immune signalling through a well known CpG DNA sensor-Toll-like receptor 9 (TLR9) or Z-DNA binding protein 1 (ZBP1, also known as DAI, which was recently reported as a potential B-form DNA sensor). Moreover, bone-marrow-transfer experiments revealed that TBK1-mediated signalling in haematopoietic cells was critical for the induction of antigen-specific B and CD4(+) T cells, whereas in non-haematopoietic cells TBK1 was required for CD8(+) T-cell induction. These data suggest that TBK1 is a key signalling molecule for DNA-vaccine-induced immunogenicity, by differentially controlling DNA-activated innate immune signalling through haematopoietic and non-haematopoietic cells.

Molecular signature of the immune and tissue response to non-coding plasmid DNA in skeletal muscle after electrotransfer

“…41 Furthermore, vaccine action has shown to occur in the absence of Zbp-1, meaning that other pathways, or a combination of pathways, are critical for vaccine action in skeletal muscle. 29 Our data also show that subtle modifications to the DNA, and thus their profile of detection by PRRs, can alter the intensity and duration of inflammation, and consequently the molecular signature of the innate immune response. Future studies are likely to reveal additional pathways for nucleic acid detection, as well as potentially important tissue differences in these pathways.…”

“…Vaccine action is already known to occur in the absence of TLR9 signalling, requiring the molecule Tbk1, which is thought to bridge PRR signalling to transcriptional activation. 29,46 However, in our array analysis, we did not detect upregulation of Tbk1 or the related molecule STING, which may partially explain the often limited immunogenicity of muscle in some trials. 41 Furthermore, vaccine action has shown to occur in the absence of Zbp-1, meaning that other pathways, or a combination of pathways, are critical for vaccine action in skeletal muscle.…”

“…The adaptor protein Irak1 was almost twofold downregulated after saline-only ET (0.53 relative expression) and upregulated to near-normal levels in pET muscle (1.19 relative expression), a twofold increase, whereas we could not detect a significant fold change in the other adaptor molecules Tbk1 or STING (Tmem173), which are implicated in vaccine action. 29 In addition to the TLR9 pathway, we identified respective 4.67-and 1.60-fold upregulation of cytoplasmic DNA detectors Zbp-1 and Trex1 after plasmid ET, but not saline ET, whereas Dhx36 was mildly upregulated in ET, but not pET samples (Figure 3a). Figure 3.…”

The TLR‐independent DNA recognition pathway in murine macrophages: Ligand features and molecular signature

“…IL-1b secretion is governed by the DNA sensor AIM2 that has recently been identified [11][12][13][14]. IFN-b production is regulated by the DNA-dependent activator of IFN-regulatory factors (DAI, formerly known as DLM-1/ZBP1) [15] and as-yet unknown DNA sensors [16,17]. With regard to the IFN pathway, it has been suggested that the B-conformation of DNA is stimulatory, whereas Z-DNA is not [9].…”

Serum amyloid P component facilitates DNA clearance and inhibits plasmid transfection: implications for human DNA vaccine

“…35,50 In brief, sera from the immunized mice were collected by tail bleeding 2 weeks after the last immunization for anti-HBsAg antibody ELISA assay. For the specific IFN-g assays, commercially available ELISA Kits (R&D Systems) were used according to their manuals.…”