Cytokines in AIDS and Cancer

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We have used the previously developed technologies of RNA optimization to optimize expression of IL-15 cytokine, and have shown that we can over-produce bioactive cytokine after DNA delivery in mice and macaques. An important conclusion this period is that DNA delivery of vectors expressing heterodimeric IL-15 leads to systemically active levels of cytokine and the increased proliferation of NK and T cells. Therefore, DNA injection is now a practical method for the delivery of IL-15 in humans. We explored the biology of IL-15 and showed that efficient production of IL-15 is possible only by co-expression in the same cell with the so-called IL-15 Receptor-alpha. We also showed that a second form of IL-15 (SSP IL-15) previously identified in humans and rodents as intracellular or nuclear IL-15 is also efficiently secreted from the cells when co-expressed with the IL-15 Receptor alpha. These results shed new light in the biology and regulation of IL-15 and provide methods for the efficient production and clinical application of this cytokine. Cell lines overproducing soluble bioactive IL-15/IL-15 Receptor alpha heterodimers have been constructed and were used for the production of the authentic bioactive form of IL-15 found in the body. IL-15 purified from over-producing human cells was injected in mice and shown to be bioactive. Extensive studies in primates have shown that heterodimeric IL-15 has favorable pharmacokinetic and pharmacodynamic properties. The extended half life of heterodimeric IL-15 is in sharp contrast to other cytokines and is in agreement with the homeostatic role of this cytokine for the immune system. Heterodimeric IL-15 has been extensively characterized and it is heavily glycosylated. IL-15 is of interest due to its ability to stimulate the growth, activation and survival of lymphocytes, including CD8 and NK cells. Thus, IL-15 has been considered for cancer immunotherapy and for support of the growth of cytotoxic cell clones after adoptive transfer. Other proposed uses of IL-15 are in lymphopenia, in supporting NK cell growth and activation after NK transfer, and as vaccine adjuvant. We have shown that IL-15 injection accelerates the recovery of lymphocytes in mice rendered lymphopenic after treatment with cytotoxic drugs. We have used optimized expression vectors to express IL-12 cytokine in animals. Efficient expression results in bioactive levels, which increase immune response after DNA vaccination, thus becoming important molecular adjuvant for our vaccines. This work established methods to optimize expression of the IL-12 family of cytokines (IL-12, IL-23, IL-27, IL-35). Efficient expression of IL-27 after DNA delivery demonstrated synergy with IL-2 in the elimination of neuroblastoma metastases in mice.