Protein-rich fraction of Protaetia brevitarsis seulensis larvae induce maturation of dendritic cells and Th1-polarization: A promising adjuvant for anticancer therapy

The objective of this study was to investigate the potential anticancer immunostimulatory properties of a protein-rich fraction obtained from larvae of Protaetia brevitarsis seulensis (PBLP), a highly nutritious edible insect, in CT-26 colon carcinoma-bearing mice. The most abundant essential amino acids (EAA) in PBLP were Val, Ile, and Leu, while the most abundant non-EAA were Pro, Glu, and Gly. PBLP increased the production of Th1-polarized cytokines and the phenotypic maturation of bone marrow-derived dendritic cells (BMDCs). PBLP-treated BMDCs stimulated naïve CD4⁺ and CD8⁺ T cells to produce IFN-γ and IL-2 but not IL-5. Significantly, dietary PBLP restored CD86 and MHC-I expression in splenic DCs, and also increased TNF-α⁺IL-2⁺IFN-γ⁺CD107⁺ polyfunctional CD4⁺ and CD8⁺ T cells in the spleen, thereby inhibiting tumor growth in CT-26 tumor-bearing mice. Collectively, PBLP synchronizes DCs and T cells for anticancer immunity, suggesting that it could serve as a potential adjuvant or supplement for cancer treatment.