Abstract
The antimicrobial and immunomodulatory activities of whey proteins and peptides make them promising candidates for protection against pathogens. To test this hypothesis, a whey protein isolate and three peptide fractions obtained from its trypsin/chymotrypsin digestion were given orally to mice for 7 days. Half the mice were then infected with Escherichia coli O157:H7 and serum cytokines and total immunoglobulin A (IgA) were measured over the next 7 days. All whey products strongly stimulated total IgA production in non-infected mice, suggesting a potential adjuvant role. The peptide fractions produced contrasting immunomodulatory effects: the neutral fraction (4.5 < pH < 7) stimulated serum interferon-gamma (IFN-γ), whereas the acidic fraction (pH < 4.5) inhibited it. In the infected model, only the basic fraction (pH > 7) induced a sustained serum IgA secretion, which coincided with increased transforming growth factor-beta 1 (TGF-β1) levels. These results indicate that some whey peptides modulate immune parameters in healthy mice, whereas the basic peptide fraction increased immune vigilance during the infection.
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