Background and aim: Studies have verified the protective effect of Hydrogen Sulfide (H2S) on gastric ulcer and ulcerative colitis, but the mechanisms are not fully illustrated. In this study, the possible protective effect of H2S on TNF-α/IFN-γ induced barrier dysfunction was investigated in Caco-2 cell monolayers.
Method: The barrier function of Caco-2 monolayers was evaluated by measuring trans-epithelial electrical resistance (TEER) and FITC-Dextran 4 kDa (FD-4) trans-membrane flux. ZO-1 and Occludin were chosen as markers of the localization of tight junction (TJ) proteins for immunofluorescence. The expression of MLCK and phosphorylation level of myosin light chain (MLC) were measured by immunoblotting. The activation of NF-kB p65 was analyzed by EMSA and immunofluorescence.
Results: NaHS at 500 uM significantly attenuated TNF-α/IFN-γ-indueced Caco-2 monolayer barrier injury. The increased expression of MLCK and increased phosphorylation level of MLC induced by TNF-α/IFN-γ was also inhibited significantly by NaHS. Additionally, NaHS inhibited TNF-α/IFN-γ induced activation and nuclear translocation of NF-kB p65.
Conclusion: The present study reveals the protective effect of H2S on TNF-α and IFN-γ-induced injury of intestinal epithelial barrier function in Caco-2 monolayers and suggests that the suppression of MLCK-P-MLC signaling mediated by NF-kB P65 might be one of the mechanisms underlying the protective effect of H2S.
Keywords: H2S; MLCK; NF-kB; Tight junction; ZO-1.