Potential of Transfected Muscle Cells to Contribute to DNA Vaccine Immunogenicity

Abstract

The mechanism(s) by which DNA vaccines trigger the activation of Ag-specific T cells is incompletely understood. A series of in vivo and in vitro experiments indicates plasmid transfection stimulates muscle cells to up-regulate expression of MHC class I and costimulatory molecules and to produce multiple cytokines and chemokines. Transfected muscle cells gain the ability to directly present Ag to CD8 T cells through an IFN-regulatory factor 3-dependent process. These findings suggest that transfected muscle cells at the site of DNA vaccination may contribute to the magnitude and/or duration of the immune response initiated by professional APCs.

DNA vaccination against a fish rhabdovirus promotes an early chemokine-related recruitment of B cells to the muscle

“…Although it seems that IgT + cells play an important role in mucosal responses [19], recent evidence implicates IgT in systemic responses as well [20]. Our results demonstrate that both IgM + and IgT + cells are recruited to the muscle upon DNA vaccination, in contrast to reports in mammals, in which macrophages, T cells and neutrophils are the predominant recruited cell types [21,22]. To gain an insight into the mechanisms responsible for this B cell mobilization, we have also studied the transcription of a wide range of chemokine genes and all chemokine receptors known for rainbow trout.…”

“…In concordance with the transcriptional studies and in contrast to the situation in higher vertebrates [21,22], high levels of both IgM and IgT were found at the injection site (Fig. 2).…”

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

“…However, more importantly, plasmid ET also initiates a strong innate immune response to the presence of DNA that appears mediated by, or at least causes upregulation of, TLR9-dependent and -independent pathways and inflammasome components, as well as costimulatory molecules that may facilitate antigen presentation to CD8 T cells. 31 Kinetics of cellular infiltration In addition to upregulation of immune system genes, we also saw evidence of tissue infiltration through increases in genes associated with cellular transport, cellular adhesion and migration, extracellular matrix organisation as well as some cell death, probably associated with phagocytosis of damaged cells (Figure 1b; Supplementary Table 9). Further characterisation of the inflammatory response was performed by histology, fluorescence-activated cell sorting (FACS) and qPCR of marker genes on whole-tissue lysate taken at different time points after ET (Supplementary Figure 2 --5).…”

“…Many co-stimulatory molecules were identified to be upregulated specifically after plasmid ET, whereas tissue damage was also associated with the upregulation of some major histocompatibility complex molecules that may impact vaccine function and/or limit gene therapy applications. 8,31 A positive feedback loop exists whereby most or all of the PRRs and DNA detection processes are induced by PRR signalling and the resulting IFN response. 30 Thus, activation of one pathway will essentially upregulate many other pathways, making it difficult to discern the contributions of each pathway to DNA detection.…”

“…Plasmid DNA induced upregulation of members of the p47 and p200 GTPase and GBP GTPase families, in addition to those associated with the 46 common tissue response genes (Figures 2b and 3b). Importantly, several co-stimulatory molecules involved in antigen presentation and associated with the muscle 31 were also induced by plasmid DNA (Figure 3b) in addition to many less characterised IFN-responsive genes not seen after saline ET (data not shown). Several important signal transducers and IRF transcription factors were also specifically upregulated after plasmid ET (Figure 3c).…”