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

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.

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.

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.

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.