Oligochitosan glycosylation of casein by TGase: Protective effect and mechanism on alcohol-induced intestinal injury in C57BL/6 mice

Abstract

Glycosylated protein by transglutaminase-type could alter the structures and functional properties of proteins. However, the beneficial effects of glycosylated proteins against alcohol-induced intestinal injury remain unclear. Herein, the protective role and mechanism of glycosylated casein ameliorating alcohol-induced intestinal injury were assessed in vivo. The results showed that glycosylated casein and casein significantly relieved alcohol-induced oxidative stress and inflammatory responses in a concentration-dependent manner. The interventions of glycosylated casein and casein decreased serum parameters, improved the activities of antioxidant enzymes, reduced levels of inflammatory cytokines, and alleviated histopathological impairment in intestine tissues. Glycosylated casein and casein treatment downregulated protein expressions of TLR4, NF-κB p65, IKB-α, and MyD88 in mice, which activated the TLR4/NF-κB signaling pathway as a protective mechanism. More importantly, glycosylated caseinate showed a better effect against alcohol-induced intestinal injury than casein, suggesting that transglutaminase-mediated glycosylation of proteins is a useful technique to enforce protein biofunctions in the intestine.