Proteins in the milk release biologically active peptides upon enzymatic digestion. In the present study, we report the identification of novel monocyte/macrophage chemotactic peptides derived from enzymatically digested bovine β-casein, a casein family member that is a major constituent of milk. β-casein fragments generated by actinase E showed potent chemotactic activity for human and mouse monocytes/macrophages, but not neutrophils, T lymphocytes or dendritic cells. The fragment-induced migration of human monocytes was inhibited by pertussis toxin and was not desensitized by a variety of known chemoattractants, suggesting that the digests activate a unique G protein-coupled receptor(s). The digests were further fractionated and purified to yield 3 small peptides. One peptide Q1 designated as "β-casochemotide-1" with the amino acid sequence of YPVEP (f114-118 of β-casein) induced high levels of macrophage chemotaxis. It also promoted calcium mobilization in macrophages, another indication of cell activation. Our study suggests that biologically active peptides released by actinase-digested milk β-casein may promote innate host immune responses by inducing macrophage migration and activation.
ASJC Scopus subject areas
- Immunology and Allergy