title: Antibody-mimetic ligand selected by mRNA display targets DC-SIGN for dendritic cell-directed antigen delivery.
abstract: Dendritic cell (DC)-based vaccines have shown promise as an immunotherapeutic modality for cancer and infectious diseases in many preclinical studies and clinical trials. Provenge (sipuleucel-T), a DC-based vaccine based on ex vivo-generated autologous DCs loaded with antigens, has recently received FDA approval for prostate cancer treatment, further validating the potential of DC-based vaccine modalities. However, direct antigen delivery to DCs in vivo via DC-specific surface receptors would enable a more direct and less laborious approach to immunization. In this study, the recombinant extracellular domains (ECD) of human and mouse DC-SIGN (hDC-SIGN and mDC-SIGN) were generated as DC-specific targets for mRNA display. Accordingly, an antibody-mimetic library was constructed by randomizing two exposed binding loops of an expression-enhanced 10th human fibronectin type III domain (e10Fn3). After three rounds of selection against mDC-SIGN, followed by four rounds of selection against hDC-SIGN, we were able to evolve several dual-specific ligands, which could bind to both soluble ECD of human and mouse DC-SIGNs. Using a cell-binding assay, one ligand, eFn-DC6, was found to have high affinity to hDC-SIGN and moderate affinity to mDC-SIGN. When fused with an antigenic peptide, eFn-DC6 could direct the antigen delivery and presentation by human peripheral blood mononuclear cell (PBMC)-derived DCs and stimulate antigen-specific CD8(+) T cells to secrete inflammatory cytokines. Taken together, these results demonstrate the utility of mRNA display to select protein carriers for DC-based vaccination and offer in vitro evidence that the antibody-mimetic ligand eFn-DC6 represents a promising candidate for the development of an in vivo DC-based vaccine in humans.
authors: Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA 90089, USA.
authors: Liang
authors: L
authors: Xiao
authors: Kuo-Chan
authors: KC
authors: Hung
authors: Terry T
authors: TT
authors: Takahashi
authors: Kye-Il
authors: KI
authors: Joo
authors: Matthew
authors: M
authors: Lim
authors: Richard W
authors: RW
authors: Roberts
authors: Pin
authors: P
authors: Wang
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D000941:Antigens / Q000008:administration & dosage* / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D040761:Biomimetic Materials; D015815:Cell Adhesion Molecules / Q000235:genetics* / Q000378:metabolism; D061505:Cell Surface Display Techniques / Q000379:methods*; D003713:Dendritic Cells / Q000276:immunology* / Q000378:metabolism; D016503:Drug Delivery Systems / Q000379:methods*; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D037181:Lectins, C-Type / Q000235:genetics* / Q000378:metabolism; D008024:Ligands; D051379:Mice; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000276:immunology / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin
chemical_list: D000906:Antibodies; D000941:Antigens; D015815:Cell Adhesion Molecules; D005353:Fibronectins; D037181:Lectins, C-Type; D008024:Ligands; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D011994:Recombinant Proteins; D000099215:DC-Specific ICAM-3 Grabbing Nonintegrin; C501364:fibronectin type III like peptide, human