AAV2/IL-12 gene delivery into dendritic cells (DC) enhances CTL stimulation above other IL-12 applications

Abstract

Adoptive transfer of antigen-specific cytotoxic T lymphocytes (CTL) holds significant promise in treating cancer and Th1 response cytokines are critical for their stimulation. Recently we reported that interleukin 7-(IL-7) and interferongamma-(IFNγ) autocrine/T cell gene delivery resulted in superior ex vivo CTL stimulation over paracrine/DC delivery. IL-12 is yet another important Th1 cytokine which affects both DC and T cells. Here, using adeno-associated virus Type 2 (AAV2) gene delivery, IL-12-paracrine/DC gene delivery gave significantly superior stimulation of carcinoembryonic antigen (CEA)-specific CTL killing over that induced by autocrine gene delivery (or exogenous IL-12 addition). This is surprising as both AAV2/IL-12-treated T cells and DC secreted approximately the same level of IL-12. Paracrine IL-12 gene delivery also resulted in highest IL-12/IL-10 secretion ratio by DC and highest CD40, CD80, CD83 and CD86 expression. Moreover, AAV2/IL-12-DC stimulated the highest T-cell IFNγ production, highest T cell proliferation, highest CD69+/CD8+ levels, and lowest level of CD25+/CD4+ Treg. These data strongly suggest that the primary activity of IL-12 during CTL generation is upon the DC. These data are also consistent with there being novel activity for IL-12 within the DC itself, not involving its surface receptor; an “intracrine” activity. Given the plethora of IL-12 studies, these data also suggest that this gene delivery comparison approach could be useful for uncovering new cytokine activities and mechanism(s) of action gone unrecognized by conventional immunologic assays. Finally, these data further suggest AAV2/IL-12 intracrine gene delivery into DC may have utility in immunotherapy protocols involving antigen-specific CTL.

The transduction pattern of IL‐12‐encoding lentiviral vectors shapes the immunological outcome

“…Under normal circumstances, endogenous IL‐12 is mainly produced by APCs. Moreover, it has been shown that IL‐12 gene delivery to DCs is superior in stimulating CTLs in an autocrine, paracrine, and even “intracrine” fashion . Therefore, it has been questioned if and how APC‐restricted delivery of IL‐12 in vivo could enhance the stimulation of CTLs , while overcoming toxic side effects.…”

Past, Present and Future Targets For Immunotherapy in Ovarian Cancer

“…Some groups have shown successful antitumor activity with reinfusion of unloaded DCs [114] or DCs that are transformed to overexpress various chemokines (such as IL-12 [115–117], CCL 21 [118], or IL-23 [119]) or antigen (p53 [120], MART [121], MUC-1 [122], or gp100 [123]). In other instances, DCs loaded ex vivo with TAA [114,115] or pulsed with RNA [124–126] have been reinfused with good effect.…”

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“…The rationale behind all these approaches is that DCs become loaded ex vivo with TAAs or TAA-coding molecules, hence becoming able to prime TAA-targeting immune responses upon reinfusion. Additional DC-based anticancer immunotherapies include the targeting of specific TAAs to DCs in vivo [169,[198][199][200][201][202][203][204][205], the use of DC-derived exosomes [206][207][208], and the (re-)administration of autologous or allogeneic DCs amplified, matured and optionally genetically modified ex vivo, but not loaded with TAAs [209][210][211][212][213][214]. In the former setting, TAAs are fused to mAbs, polypeptides or carbohydrates that selectively bind to DCs [169, 198-202, 215, 216], encapsulated in DC-targeting immunoliposomes [217,218], or (3) encoded by DC-specific vectors [219][220][221].…”

“…In the former setting, TAAs are fused to mAbs, polypeptides or carbohydrates that selectively bind to DCs [169, 198-202, 215, 216], encapsulated in DC-targeting immunoliposomes [217,218], or (3) encoded by DC-specific vectors [219][220][221]. In the latter scenarios, DCs or their exosomes are administered as a relatively non-specific immunostimulatory intervention [209][210][211][212][213]. Interestingly, one cellular product containing a significant proportion of (partially immature) DCs is currently licensed for use in cancer patients, namely sipuleucel-T (also known as Provenge ® ) (source http:// www.fda.gov).…”