Protective effect of carboxytmethylpachymaran on TNF-α-induced damage in Caco-2 cell monolayers

This study was carried out to study the protective effect of carboxytmethylpachymaran (CMP) on TNF-α-induced intestinal epithelial barrier dysfunction in Caco-2 cell monolayers and the underlying mechanism. The Caco-2 cell monolayers were pretreated with 50, 100 or 150 μg/mL CMP for 72 h, and then they were exposed to 100 ng/mL tumor necrosis factor alpha (TNF-α) for 72 h. The results showed that CMP alleviated the drop of trans-epithelial electrical resistance (TEER) and the increase of phenol red flux induced by TNF-α. CMP also ameliorated TNF-α-induced decrease of mRNA/protein expression and distribution of Occludin and ZO-3 which were chosen as makers of tight junction (TJ). Additionally, the increased protein expressions of MLCK, phosphorylation level of myosin light chain (p-MLC), NF-κB p-P65 and p-IκBα induced by TNF-α were significantly inhibited by CMP. This study demonstrates the protective effect of CMP on TNF-α-induced damage of intestinal epithelial barrier in Caco-2 monolayers and discovers that the suppression of MLCK-p-MLC signaling regulated by NF-κB might be one of the mechanisms underlying the protective effect of CMP.