A novel MtHSP70-FPR1 fusion protein enhances cytotoxic T lymphocyte responses to cervical cancer cells by activating human monocyte-derived dendritic cells via the p38 MAPK signaling pathway

Abstract

ObjectiveTo evaluate the potential effects of recombinant mycobacterium tuberculosis heat shock protein 70-formyl peptide receptor 1 (MtHSP70-FPR1) fusion protein on human monocyte-derived dendritic cell (moDC) maturation; cytotoxic T lymphocyte (CTL) responses to cervical cancer (CC) cells; and the roles of the p38 MAPK, ERK, and JNK pathways in its transition. MethodsMonocytes were positively selected with a MACS column with antiCD14 antibody-conjugated microbeads from umbilical cord blood. MoDCs were stimulated with MtHSP70-FPR1, MtHSP70, a mix of MtHSP70 and FPR1, FPR1, or phosphate buffer solution (PBS) as control. Flow cytometry was used to analyze the surface molecule expression of moDCs and IFN-γ-producing CD8+ T cells. T cell proliferation was assessed using [3][H]-thymidine assays. The cytotoxicity of moDC-activated T cells against CC cells was evaluated by MTT assays. Cytokine production was determined by enzyme-linked immunosorbent assay. Western blotting was used to investigate protein expression. ResultsCompared with MtHSP70, MtHSP70 + FPR1, FPR1, or PBS-mediated moDCs, MtHSP70-FPR1-pulsed moDCs expressed higher levels of CD80, CD86, CD83, HLA-DR, and CCR7; secreted more IL-12p70, TNF-ɑ and IL-1β; and elicited stronger CTL priming and proliferation, resulting in an effective, HLA-I-dependent killing effect on CC cells. The p38 MAPK, ERK, and JNK pathways were all activated in MtHSP70-FPR1-mediated moDC maturation, but the p38 MAPK pathway played a vital role. ConclusionsThe excellent capability of MtHSP70-FPR1 fusion protein to induce phenotypical and functional maturation of moDCs and CC-specific CTL responses partly illustrates the potential clinical benefits of DC-based immunotherapy for CC.