Gene delivery to dendritic cells facilitated by a tumor necrosis factor alpha-competing peptide

Efficient gene delivery systems tailor-designed for dendritic cells (DCs) would allow the possibility of therapeutic manipulation of a wide spectrum of immune functions. Toward achieving this goal, we have identified a novel heptameric peptide (YTYQGKL) that functions as a localization moiety to mediate gene transfer in murine DCs. The sequence was identified by screening a phage display library against a DC cell line (JAWSII) using mouse TNFalpha as the eluting ligand. Alignment analysis reveals YTYQGKL resembles a solvent accessible region in mouse and human TNFalpha structures. A cyclized synthetic peptide bearing the sequence CYTYQGKLC binds to DCs in a concentration-dependent manner. Appending the cyclic peptide to a DNA binding domain (16 consecutive lysine residues) enhances transfection of reporter gene-encoding plasmids in JAWSII cells and in bone marrow derived primary DCs (BMDC). Further enhancement of gene transfer was observed when the peptide-DNA construct was anchored onto polymeric microspheres, with up to 25% of BMDC expressing the transgene. Exposing cells to the free peptide prior to transfection significantly diminished transgene expression. These results demonstrate that YTYQGKL can be used to facilitate gene transfer in DCs.