Engineering of a self-adjuvanted iTEP-delivered CTL vaccine

Abstract

Cytotoxic T lymphocyte (CTL) epitope peptide-based vaccines are widely used in cancer and infectious disease therapy. We previously generated an immune-tolerant elastin-like polypeptides (iTEPs)-based carrier to deliver a peptide CTL vaccine and enhance the efficiency of the vaccine. To further optimize the vaccine carrier, we intended to potentiate its function by designing an iTEP-based carrier that was able to deliver adjuvant and a vaccine epitope as one molecule. Thus, we fused a 9-mer H, a peptide derived from the high-mobility group box 1 protein (HMGB1) that could induce activation of dendritic cells (DCs), with an iTEP polymer to generate a new iTEP polymer named H-iTEP. The H-iTEP still kept the feature of reversible phase transition of iTEPs and should be able to be used as a polymer carrier to deliver peptide vaccines. The expression levels of CD80/CD86 on DCs were assessed using flow cytometry. The iTEP fusion-stimulated IL-6 secretion by DCs was measured with ELISA. Activation of antigen-specific CD8 T cells induced by iTEP fusions was examined through a B3Z hybridoma cell activation assay. In vivo CTL activation promoted by iTEP fusions was detected by an IFN-γ-based ELISPOT assay. The iTEP fused with H could induce maturation of DCs in vitro as evidenced by increased CD80 and CD86 expression. The iTEP fusion also promoted activation of DCs by increasing secretion of a proinflammatory cytokine IL-6. The N-terminus or C-terminus fusion of H to iTEP had a similar effect and a reduced form of cysteine in iTEP fusions was required for DC stimulation. iTEP fusions potentiated a co-administrated CTL vaccine by increasing an antigen-specific CTL response in vitro and in vivo. When the H-iTEP was fused to a CTL epitope to generate a one-molecule vaccine, this self-adjuvanted vaccine elicited a stronger antigen-specific CTL response than a vaccine adjuvanted by Incomplete Freund's Adjuvant. Thus, we have successfully generated a functional, one-molecule iTEP-based self-adjuvanted vaccine.

Triggered Immune Response Induced by Antigenic Epitopes Covalently Linked with Immunoadjuvant-Pulsed Dendritic Cells as a Promising Cancer Vaccine

“…These findings are consistent with previous studies indicating that the free HMGB-1-derived peptide has almost no effect on the maturation and activation of DCs [31]. They are also consistent with results of studies showing that the adjuvant covalently linked to the short peptides could stimulate higher epitope recognition than the physically mixed formulation of the same molecules [39,40].…”

“…As mentioned previously, the success of peptide-based vaccines mainly depends on the utilized peptides and selection of an appropriate adjuvant. Herein, it has been found that the covalent linking of adjuvant to tumor-associated antigens (TAAs) could result in the maturation and activation of DCs in vitro and induced a potent antitumor immune response in vivo compared to TAAs which they physically mixed with adjuvant [30,31].…”

Depletion of PD-1-positive cells ameliorates autoimmune disease

“…The linker was also inserted in between the ABD domain and the PE domain of ABD-PE. The coding genes of αPD-1-ABD-PE and αPD-1-PE were generated by fusing the synthesized genes together using a previously described protocol 52,53 . Meanwhile, a gene that encodes the linker was inserted between the genes of αPD-1…”

A modified HLA-A*0201-restricted CTL epitope from human oncoprotein (hPEBP4) induces more efficient antitumor responses

“…42,43 To evaluate the risk of autoimmunity induction by overexpressed self-antigen-derived peptide vaccinations, several preclinical and clinical trials have demonstrated that peptides derived from overexpressed self-antigens were able to induce effective and specific CTL responses without any serious systemic adverse events. [44][45][46][47] However, studies by Overwijk and Restifo 48 and Overwijk et al 49 revealed that potent CD8 + T-cell responses induced with MDA in melanoma patients could interact with melanocytes in the skin, resulting in autoimmune depigmentation. Therefore, if hPEBP4-derived peptides are to serve as candidates for CTL-based immunotherapy against breast cancer or other hPEBP4-expressing carcinomas, their safety and tolerability need to be further assessed in basic and clinical studies.…”