Protective effects of glutathione on oxidative injury induced by hydrogen peroxide in intestinal epithelial cells

Background: Reactive oxygen species are increased in multiple gastrointestinal diseases and contribute to their pathogenesis. glutathione (GSH) is an antioxidant that helps to prevent reactive oxygen species-mediated mucosal damage. This study examines the mechanisms by which GSH attenuates hydrogen peroxide (H₂O₂)-induced injury in intestinal epithelial cells.

Methods: IEC-6 cells were cultured and treated with H₂O₂ ± GSH. Inflammation was measured by nuclear factor kappa-B (NF-κB) P65 expression, NF-κB nuclear translocation, iκBα phosphorylation, and interleukin 1 beta secretion. Terminal deoxynucleotidyl transferase-mediated UTP end-labeling staining and cleaved caspase-3 were used to assess apoptosis. The role of P38 mitogen-activated protein kinase (P38 MAPK) signaling was examined using the P38 MAPK agonist U46619 and inhibitor SB203580 in H₂O₂ and GSH-treated cells. Phosphorylated and total P38 MAPKs and cleaved caspase-3 were measured by Western blot. Data are means ± standard deviation, statistical significance P < 0.05 by student's t-test, or one-way analysis of variance.

Results: Pretreatment with GSH attenuates the activation of NF-κB and P38 MAPK signaling pathways by H₂O₂. GSH also decreased H₂O₂-mediated increases in interleukin 1 beta secretion, cleaved caspase-3 activation, and apoptosis in IEC-6 cells. SB203580 attenuated the increase in apoptosis and cleaved caspase-3 in H₂O₂-treated cells. The increase in apoptotic index and cleaved caspase-3 observed in U46619-treated cells was also diminished by GSH.

Conclusions: GSH appears to ameliorate oxidative injury in intestinal epithelial cells by attenuating H₂O₂-mediated activation of NF-κB and P38 MAPK signaling pathways that regulate intestinal inflammation and apoptosis.