Characterization of a plasma-derived protein fraction from Magallana gigas and its modulatory effects on lipopolysaccharide-induced inflammatory responses in HT-29 cells.

A plasma-derived protein fraction (MG-1) was partially purified from the hemolymph of the Pacific oyster, Magallana gigas, and its potential modulatory effects on lipopolysaccharide (LPS)-induced inflammatory responses were evaluated in HT-29 intestinal epithelial cells. SDS-PAGE analysis revealed two major protein bands, MG-11 and MG-12, which shared identical peptide sequences based on LC-MS/MS analysis and may represent different molecular forms of the same protein. The reconstructed MG-12 sequence consisted of 192 amino acid residues and exhibited similarity to previously reported cavortin-like proteins.MG-1 showed no detectable cytotoxicity at concentrations up to 500 μg/mL. LPS exposure reduced cell viability and increased the production of inflammatory mediators, whereas MG-1 treatment was associated with partial attenuation of these responses. MG-1 also reduced the expression of Toll-like receptor 4 (TLR4), myeloid differentiation factor 2 (MD-2), cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS), prostaglandin E₂ (PGE₂), and several inflammation-related cytokines. In addition, phosphorylation of nuclear factor-kappa B (NF-κB), extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase (JNK) was decreased following MG-1 treatment. These findings suggest that MG-1 attenuates LPS-induced inflammatory signaling in HT-29 cells; however, the present study does not provide direct evidence of a molecular interaction between MG-1 and LPS. However, direct molecular interactions were not demonstrated and require further validation.These findings provide preliminary evidence that MG-1 may influence LPS-induced inflammatory responses in intestinal epithelial cells and warrant further investigation of oyster-derived plasma proteins.