Bovine β-Casein Peptide YPFPGPIH Regulates Inflammation and Macrophage Activity via TLR/NF-κB/MAPK Signaling.

Food-derived bioactive peptides are known to possess immunomodulatory properties, although their molecular mechanisms remain incompletely characterized. In this study, we investigated the immunoregulatory effects and underlying mechanisms of YPFPGPIH, a peptide derived from bovine β-casein, using the RAW264.7 macrophage model. Our results demonstrate that YPFPGPIH enhanced macrophage proliferation and phagocytosis in a dose-dependent manner and promoted chemotactic migration through the upregulation of monocyte chemoattractant proteins MCP-1 and MCP-3. Under lipopolysaccharide (LPS)-induced inflammatory conditions, YPFPGPIH significantly reduced the levels of pro-inflammatory mediators, including interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and nitric oxide (NO), while increasing the production of the anti-inflammatory cytokine interleukin-10 (IL-10), thereby reestablishing cytokine balance. Mechanistic studies revealed that YPFPGPIH inhibited LPS-induced activation of the NF-κB and MAPK pathways, as indicated by reduced nuclear translocation of p65 and decreased phosphorylation of ERK, JNK, and p38. Molecular docking analysis indicated strong binding affinities between YPFPGPIH and Toll-like receptors TLR2 and TLR4, suggesting the involvement of TLR-mediated signaling. Notably, YPFPGPIH downregulated inducible nitric oxide synthase (iNOS) expression and upregulated chemokine mRNA levels, reflecting its dual role in modulating inflammatory and migratory responses. These findings highlight YPFPGPIH as a multifunctional immunomodulatory peptide that fine-tunes macrophage activity through crosstalk between TLR, NF-κB, and MAPK signaling pathways. This study provides new insights for developing peptide-based therapeutics and functional foods aimed at managing inflammatory diseases.