Transglutaminase-Mediated Caseinate Oligochitosan
Glycation Enhances the Effect of Caseinate Hydrolysate to Ameliorate
the LPS-Induced Damage on the Intestinal Barrier Function in IEC‑6
Cells
Some food components can regulate
the intestinal barrier function.
Herein, the effect of transglutaminase-type oligochitosan glycation
on caseinate hydrolysate for its ability to maintain intestinal epithelial
integrity and the tight junction (TJ) structure was investigated by
assessing and comparing the bioactivities of glycated caseinate hydrolysate
and caseinate hydrolysate against the lipopolysaccharide-induced barrier
damage in the model cells (rat intestinal epithelial IEC-6 cells).
The results from liquid chromatography with tandem mass spectrometry
(LC-MS/MS) analysis demonstrated that oligochitosan glycation occurred
at the Gln residues of α-S1-casein and α-S2-casein. The
two hydrolysates retarded the lipopolysaccharide cytotoxicity toward
IEC-6 cells and enhanced the barrier integrity by increasing the transepithelial
electrical resistance or decreasing the paracellular permeability.
In addition, these two hydrolysates could upregulate both mRNA and
protein expression of three TJ proteins in IEC-6 cells. More importantly,
the glycated caseinate hydrolysate had higher potential than caseinate
hydrolysate to protect IEC-6 cells against the lipopolysaccharide-induced
barrier damage, suggesting that the transglutaminase-mediated oligochitosan
glycation of proteins is a useful approach to enforce protein biofunctions
in the intestine.