Aim of the study
The aim of this study was to investigate the protective effects of TC extract on inflammatory responses and intestinal barrier dysfunction in lipopolysaccharide (LPS)-stimulated Caco-2 cells. Materials and
Conclusion
Our findings suggest that ethanolic extract of TC could attenuate the LPS-induced intestinal barrier dysfunction by increasing the TJ protein and suppressing inflammatory responses.
Methods
The inhibitory effect of TC on nitric oxide (NO) and pro-inflammatory cytokines production were determined by Griess reagent and enzyme-linked immunosorbent assay, respectively. The epithelial permeability was evaluated by transepithelial electrical resistance (TEER) assay, and inflammation- and tight junction (TJ)-related protein expression were analyzed by Western blotting. In addition, the presence of ten active compounds was identified and quantified using UHPLC-ESI-MS and HPLC-DAD analyses.
Results
Treatment with TC significantly reduced NO production and pro-inflammatory cytokines production [interleukin (IL)-6 and tumor necrosis factor (TNF)-α] compared to the group treated with LPS only, particularly at 100 μg/mL. TC significantly decreased monolayer permeability as detected by TEER. In addition, the transmission of fluorescein isothiocyanate-dextran 4 across the barrier was decreased after treatment with TC. Inflammation-related proteins (inducible NO synthase, cyclooxygenase-2, TNF-α, IL-6, and IL-1β) were down-regulated after treatment with TC. In contrast, TC significantly increased the protein levels of the TJ-related protein, claudin-5. Ten phytochemicals (protocatechuic acid, chlorogenic acid, caffeic acid, scopoletin, chicoric acid, hyperoside, nicotiflorin, luteoloside, sophoricoside, and luteolin) were identified by UHPLC-ESI-MS and HPLC-DAD analysis.