Multiepitope Trojan Antigen Peptide Vaccines for the Induction of Antitumor CTL and Th Immune Responses

Abstract

We describe in this study a strategy to produce synthetic vaccines based on a single polypeptide capable of eliciting strong immune responses to a combination CTL and Th epitopes with the purpose of treating malignancies or preventing infectious diseases. This strategy is based on the capacity of Trojan Ags to deliver exogenous Ags into the intracellular compartments, where processing into MHC-binding peptides takes place. Our previous work demonstrated that Trojan Ags containing a CTL epitope localized to intracellular compartments, where MHC class I-binding peptides were generated in a TAP-independent fashion by the action of various exopeptidases and the endopeptidase furin. In this study, we report that Trojan Ags containing several CTL epitopes joined via furin-sensitive linkers generated all of the corresponding MHC class I-binding peptides, which were recognized by CTL. However, Trojan Ags prepared with furin-resistant linkers failed to produce the MHC class I-binding peptides. We also present data indicating that Trojan Ags bearing both CTL and Th epitopes can generate the corresponding MHC class I- and II-binding peptides, which are capable of stimulating T cell responses. Most significantly, in vivo vaccination of mice with a single injection of multiepitope Trojan Ags resulted in strong CTL and Th responses that translated into significant antitumor responses in a model of malignant melanoma. The overall results indicate that Trojan Ags prepared with furin-sensitive linkers are ideal candidates for producing synthetic multiepitope vaccines for the induction of CTL and Th responses that could be used against a variety of diseases, including cancer.

Furin-Processed Antigens Targeted to the Secretory Route Elicit Functional TAP1−/−CD8+ T Lymphocytes In Vivo

“…Both furin (11,12) and cathepsin S (14) have been involved in TAP-independent cross-priming of immunogens that originate from an exogenous source. However, as the cytosolic proteins Ova and cC-Ova did not induce CD8 ϩ T lymphocytes in TAP1-deficient mice, the evidence suggests that the potential of constructs like sC-Ova⌬C for in vivo immunization depends on direct priming by professional APC rather than on cross-priming.…”

“…There is evidence for TAP-independent pathways of Ag presentation by MHC class I molecules (4,5). The proteases involved include ER signal peptidase, trans-Golgi network furin and cathepsins for endogenously synthesized proteins (6 -10) and for internalized Ags (11)(12)(13)(14).…”

“…Notably, when chimeric proteins containing a MHC class I epitope downstream of furin cleavage sites are directed to the secretory pathway in TAP-negative cells, so that there is no contribution from cytosolic epitopes, antigenic presentation is elicited in a strictly furindependent fashion (8,9). Furin is also essential for generating MHC class I ligands from some exogenous Ags (11,12). Considering these capabilities, we have explored the potential of the furin-mediated secretory pathway of Ag processing to generate in vivo a compensatory and effective CD8 ϩ T lymphocyte response in TAP-deficient mice and the potential relevance of this mechanism to contribute to overall MHC class I Ag presentation also in TAP-positive individuals.…”

An Anti-Nucleic Acid Antibody Delivers Antigen to the Cross-Presentation Pathway in Dendritic Cells and Potentiates Therapeutic Antitumor Effects

“…Draining lymph node CD11c + DCs from mice cross presented OVA 48 h after injection of 3D8-OVA [250][251][252][253][254][255][256][257][258][259][260][261][262][263][264] . Ag targeting to the cross-presentation pathway in DCs has been studied using Ags coupled to carriers such as cell-penetrating peptides (CPPs) (27)(28)(29), endocytosed Hsps (9,30), and Abs against DC-specific endocytic receptors, including DC-SIGN and DEC205 (26). In particular, Ag targeting to the cross-presentation pathway in both murine and human DCs has been extensively studied by Steinman's group, using an anti-DEC205 Ab (31,32).…”

Whole protein and defined CD8+ and CD4+ peptides linked to penetratin targets both MHC class I and II antigen presentation pathways

“…33 When the HIV-I Tat peptide was linked to multiple CD8 and CD4 epitopes from OVA and furin-sensitive linker sequences were incorporated, potent CTL and Th responses were induced in vivo which showed striking prophylactic and therapeutic tumor protection against B16.OVA. 24 Previously, we have shown that immunizing mice with penetratin linked to the tumor-associated Mucin 1K b -restricted CTL peptide (MUC1-K b ), induced strong antigen-specific T-cell responses in vivo and tumor protection. 20 In the same study, mice immunized with penetratin linked to MUC1FP glutathione S-transferase fusion protein comprising of five variable number of tandem repeats from MUC1-induced antitumor responses in vivo.…”