The Immune Activity of PT-Peptide Derived from Anti-Lipopolysaccharide Factor of the Swimming Crab Portunus trituberculatus Is Enhanced when Encapsulated in Milk-Derived Extracellular Vesicles

PT-peptide is derived from the anti-lipopolysaccharide factor of the swimming crab Portunus trituberculatus. The peptide, consisting of 34 amino acids, contains a lipopolysaccharide binding domain. In this study, we investigated the effect of PT-peptide encapsulated in raw milk-derived extracellular vesicles (EVs), designated as EVs-PT peptide, on immune regulation. The results showed that raw milk-derived EVs efficaciously delivered the PT-peptide into monocytes and elevated immune activity, including reactive oxygen species level, superoxide anion production, and phagocytosis. PT-peptide and EVs-PT peptide also elevated the secretion of cytokines, such as interferon-γ, interleukin-6, and tumor necrosis factor-α in human monocytic THP-1 cells. These results suggest that the PT-peptide could be developed as an immune stimulator.