A novel endogenous antimicrobial peptide CAMP(211-225) derived from casein in human milk

A large number of bioactive peptides derived from breast milk have been identified to be multifunctional having anti-inflammatory, immunoregulatory and antimicrobial activities. Here, we report that an endogenous peptide located at beta-casein 211-225 amino acid from human breast milk (hereafter called CAMP(211-225)) presents specific antimicrobial activity against pathogenic E. coli and Y. enterocolitica. CAMP(211-225) is a novel peptide that occurs at higher levels in preterm milk than in term milk. The minimal inhibitory concentrations (MIC) of CAMP(211-225) against E. coli and Y. enterocolitica are 3.125 mu g ml(-1) and 6.25 mu g ml(-1), respectively, and the antimicrobial activity of CAMP(211-225) was also confirmed by a disk diffusion assay. Further studies using fluorescence staining, scanning electron microscopy and a DNA-binding assay revealed that CAMP(211-225) kills bacteria through a membrane-disrupting mechanism, but not by binding to intracellular nucleic acids. Neonatal necrotizing enterocolitis (NEC) is a devastating gastrointestinal disease in neonatal intensive care units. In our study, CAMP(211-225) administration effectively reduced ileal mucosa damage in an experimental NEC mice model. These results suggest that the antimicrobial peptide CAMP(211-225) may have potential value in the prevention and treatment of neonatal infections.