Fig. 2. Intracellular glutathione imbalance sensitizes hepatocytes to TNFα cytotoxicity.

a, b Both HepG2 (a) and NCTC1469 cells (b) were exposed to complete DMEM containing H₂O₂ (0.2 mM) for the indicated time periods. Intracellular GSH and GSSG levels were measured, and the GSSG/GSH ratios were calculated. All values are denoted as the mean ± SD from three or more independent studies. Bars with different characters differ significantly (p < 0.05). c, d H₂O₂ sensitizes hepatocytes to TNFα-induced cell death. HepG2 (c) and NCTC cells (d) were pretreated with H₂O₂ (0.1 and 0.2 mM) for 2 h before the addition of TNFα (40 ng/mL). Cell death was measured 16 h later by LDH release assay. Bars with different characters differ significantly (p < 0.05). e Hoechst 33342 staining. Arrows denote apoptotic bodies. f Western blot analysis of PARP cleavage. HepG2 cells were pretreated with H₂O₂ (0.2 mM) for 2 h, followed by TNFα (40 ng/mL) stimulation. Whole-cell lysates were collected and subjected to western blot for the detection of PARP cleavage. g DNA fragmentation ELISA assay. h Caspase-3 activities. Bars with different characters differ significantly (p < 0.05)