Discovery of KC-1: a novel porcine dendritic cell-targeting peptide with potential applications in swine vaccine design.

Abstract

Dendritic cells (DCs) are key antigen-presenting cells essential for initiating and regulating immune responses. While DC targeting has proven to be an effective strategy for vaccine enhancement, and targeting peptides have been extensively utilized as efficient delivery tools in DC-targeted drug and vaccine development, there remains a notable scarcity of peptides specifically selected through porcine dendritic cell screening platforms. In this study, phage display biopanning was employed to identify a novel DC-targeting peptide, designated KC (KCCYPNQMAAFA). Systematic alanine-scanning mutagenesis identified the N-terminal hexapeptide KC-1 (KCCYPN) as the minimal functional epitope responsible for DC binding. In addition to DCs, KC-1 also demonstrated selective binding to bone marrow-derived dendritic cells(BM-DCs)and porcine alveolar macrophages (PAMs) but exhibited no interaction with intestinal porcine epithelial (IPI) cells, swine testis (ST) cells, or Vero cells. Further analysis revealed that KC-1 specifically binds to the N-terminal region (1-126 aa) of SLA-DRB1, which is a key domain of the MHC II β-chain involved in the formation of the peptide-binding groove. Using the Porcine Epidemic Diarrhea Virus (PEDV) S1 subunit as a model antigen, we further evaluated the immunomodulatory effects of KC-1 on DCs in vitro. The results demonstrated that KC-1-S1 significantly promoted DCs maturation and T-cell proliferation, accompanied by increased secretion of IL-4, IL-12, and IFN-γ. These findings indicate that KC-1-S1 enhances the overall immunogenicity of the antigen, triggering a robust and mixed immune response encompassing both Th1- and Th2-type cytokine profiles compared to controls. Collectively, this study characterizes the binding profile and preliminary immunomodulatory activity of the novel peptide KC-1 at the cellular level, providing basic experimental data and a reference for further development of porcine DC-targeted antigen delivery strategies.