Factors involved in the maturation of murine dendritic cells transduced with adenoviral vector variants

Abstract

Adenoviral vector (Ad)-mediated gene transfer is an attractive method for manipulating the immunostimulatory properties of dendritic cells (DCs) for cancer immunotherapy. DCs treated with Ad have phenotype alterations (maturation) that facilitate T cell sensitization. We investigated the mechanisms of DC maturation with Ad transduction. Expression levels of a maturation marker (CD40) on DCs treated with conventional Ad, fiber-modified Ads (AdRGD, AdF35, AdF35DeltaRGD), or a different serotype Ad (Ad35) were correlated with their transduction efficacy. The alphav-integrin directional Ad, AdRGD, exhibited the most potent ability to enhance both foreign gene expression and CD40 expression, and induced secretion of interleukin-12, tumor necrosis factor-alpha, and interferon-alpha in DCs. The presence of a foreign gene expression cassette in AdRGD was not necessary for DC maturation. Maturation of DCs treated with AdRGD was suppressed by destruction of the Ad genome, inhibition of endocytosis, or endosome acidification, whereas proteasome inhibition increased CD40 expression levels on DCs. Moreover, inhibition of alphav-integrin signal transduction and blockade of cytokine secretion affected the maturation of DCs treated with AdRGD only slightly or not at all, respectively. Thus, our data provide evidence that Ad-induced DC maturation is due to Ad invasion of the DCs, followed by nuclear transport of the Ad genome, and not to the expression of foreign genes.

Novel Technologies for Vaccine Development

“…Attempts have therefore been made to improve the growth characteristics of the current vaccine backbone (i.e., PR8 virus). This effect was mediated by a tyrosine residue at position 360 of PB2 and a glutamic acid residue at position 55 of NS1 (Murakami et al 2008). Similar findings were made in MDCK cells (Murakami et al 2008).…”

“…High-growth capability is particularly important in the event of a severe pandemic, when there will be an overwhelming demand for vaccine to the novel virus. Further testing showed the highest virus titers for a vaccine virus possessing the H5N1 HA and NA genes; the PB2, PB1, PA, NP, and M genes of PR8(UW) virus; and the NS gene of PR8(Cambridge) virus (Murakami et al 2008). One study compared the growth properties of the PR8 Cambridge isolate [termed PR8(Cambridge); one of the isolates used for vaccine production] with another isolate [PR8 (UW)], which was found to replicate more efficiently in embryonated chicken eggs than PR8(Cambridge) when tested with the HA and NA genes of a highly pathogenic H5N1 viruses (Horimoto et al 2007).…”

“…Upon activation DCs migrate to the draining lymph nodes (LNs) and simultaneously upregulate costimulatory molecules and cytokines to prime both T helpers (Th) and CTLs in paracortical areas of LNs (Fig. Besides, Ad5 vectors exhibit adjuvant effect on their own and are capable of inducing DC activation and maturation upon transduction (Geutskens et al 2000;Kanagawa et al 2008). DCs thus provide a link between innate and adaptive immunity.…”

Adenoviral Vectors: Potential and Challenges as a Gene Delivery System

“…Several of the anti-cancer therapies utilizing AdV have coupled the vector with the DC's abilities in order to generate an effective anti-tumor therapy. This method offers several advantages: (1) the AdV demonstrates adjuvant activity and has the ability to activate DCs and promote maturation which facilitates the induction of strong anti-tumor response (Geutskens et al, 2000;Kanagawa et al, 2008) , (2) AdV expression of TAA within DCs permits processing and loading onto both MHCI and MHCII molecules which stimulates the appropriate and relatively persistent activation of CD8+/CD4+ responses (Xia et al, 2006), and (3) ex vivo treatment of DCs with AdV evades any potential problems with pre-existing vector immunity (Wan et al, 1999).…”

Adenoviral Vector-Based Strategies for Cancer Therapy

“…Ad transduced DCs-based cancer gene therapy offers several advantages. For example, apart from transferring immune activating genes, the Ad vector, on its own, exhibits adjuvant effects and has ability to induce DC activation and maturation, which further assist in induction of stronger anti-tumor immune responses [209, 210]. Ad vector-delivered TAA is expressed intracellularly, processed and loaded onto both MHC I and MHC II molecules, thus allowing appropriate and relatively persistent induction of CD8+ as well as CD4+ responses [208].…”