Atractylenolide III ameliorates DSS-induced colitis by improving intestinal epithelial barrier via suppressing the NF-κB-Mediated MLCK-pMLC signaling pathway

This study is to demonstrate the protection of atractylenolide III (AT III) on intestinal barrier dysfunction in ulcerative colitis (UC). UC model was established by 3% dextran sulfate sodium (DSS), and TNF-α was used to induce dysfunction in the intestinal epithelial barrier. TEER, FD-4 transmembrane flux and DAI were measured. Histopathological changes was identified by H&E staining, TJ structure changes were observed by TEM, IL-1β and TNF-α contents were measured by ELISA, bacterial translocation was investigated by FISH. The expressions of ZO-1, occludin, and the proteins in the MLCK/p-MLC and NF-κB pathways were analyzed by Western blotting or immunofluorescence. The results indicated that AT III alleviate the symptoms of DSS-induced colitis, reduce the disruption of intestinal epithelial barrier, and decrease FD4. Moreover, AT III inhibited the destruction of intestinal epithelial TJ structure and bacterial translocation in UC mice. AT III reversed the high levels of IL-1β and TNF-α, the decrease of occludin, ZO-1 expressions. Furthermore, AT III showed similar effects to PDTC (pyrrolidinedithiocarbamate) in ameliorating the disruption of the TNF-α-induced TEER and FD-4 disruption, MLCK protein expression, and MLC2 phosphorylation. In conclusion, AT III mitigates the dysfunction of intestinal epithelial barrier in UC through the NF-κB-mediated MLCK/p-MLC signaling pathway.