Dendritic cells (DC) orchestrate several crucial steps of adaptive immunity, including both the activation of naive T cells and the regulation of their subsequent phenotype and function. Hence, antigen-expressing DCs have been used as the basis of over 100 clinical trials. These trials typically involve DC """"""""maturation"""""""" of monocyte-derived DCs to upregulate costimulatory and antigen-presenting molecules and often further """"""""activation"""""""" to increase production of TH1 cytokine, IL-12. However, modest clinical outcomes of DC vaccine trials for the treatment of cancer dictate the refinement of vaccine design. While many potential tumor antigens have been identified, development of methods to enhance DC antigen presentation has lagged. Toward this goal, we have developed several strategies to manipulate the survival and/or activation state of DCs as a means to enhance the function of DCs and overcome potential tolerogenic mechanisms. These include engineering a drug-inducible CD40 (iCD40) receptor that permits temporally controlled DC-specific activation within the context of an immunological synapse, downregulation of c-Cbl in DCs to stabilize endogenous CD40 expression following ligand binding, and development of an """"""""optimized"""""""" lipid raft-targeted constitutive Akt-1 molecule, MyrF-deltaAkt that extends DC survival and maturation following growth factor withdrawal. Our central hypothesis is that enhancing the maturation and activation of DCs after injection in vivo should increase the """"""""window of interaction"""""""" with naive T cells in lymph nodes, leading to a more robust anti-tumor immune response. To test this hypothesis and further develop enhanced DCs (eDCs) for clinical applications, we propose three specific aims: (i) Determine whether enforced expression of MyrF-deltaAkt, in DCs can extend their survival and potency in vivo, leading to improved antigen presentation and anti-tumor immunity against poorly immunogenic tumor cells, (ii) Test the hypothesis that suppression of c-Cbl in DCs can stabilize CD40 and improve the efficacy of DC-based vaccines, (iii) Compare the efficacy of human DCs engineered to express MyrF-deltaAkt iCD40 or treated with c-Cbl si-RNA for migratory capacity and efficacy in vitro against defined antigens and in a human LCL tumor-based xenograft model. These three aims should ultimately lead to improved clinical applications of DCs for not only treating malignancy but numerous pathogens, as well.
| Narayanan, Priyadharshini; Lapteva, Natalia; Seethammagari, Mamatha et al. (2011) A composite MyD88/CD40 switch synergistically activates mouse and human dendritic cells for enhanced antitumor efficacy. J Clin Invest 121:1524-34 |
| Chiou, Shin-Heng; Shahi, Payam; Wagner, Ryan T et al. (2011) The E3 ligase c-Cbl regulates dendritic cell activation. EMBO Rep 12:971-9 |
| Lapteva, Natalia; Seethammagari, Mamatha R; Hanks, Brent A et al. (2007) Enhanced activation of human dendritic cells by inducible CD40 and Toll-like receptor-4 ligation. Cancer Res 67:10528-37 |
