PSI-1 Effects of arginine, tryptophan, and threonine on cell viability, antioxidant capacity, and tight junction gene expression of chicken intestinal epithelial cells induced with oxidative stress.

The objective of this study was to investigate the effects of arginine (Arg), tryptophan (Trp), and threonine (Thr) on cell viability, antioxidant capacity, and tight junction-related gene expression in chicken intestinal epithelial cells (cIECs) induced with oxidative stress. The cIECs were isolated from 16-d-old specific pathogen-free (SPF) chicken embryos. The cells were grown in fibronectin-coated plastic culture dishes in growth medium (DMEM, 2.5% FBS, 10 μg/mL insulin, 100 μg/mL penicillin/streptomycin, 2.5 mg/mL gentamicin, and 20 ng/mL epidermal growth factor) and incubated at 37℃ with 5% CO2. The cells were exposed to 0 (control), 250, and 500 μM supplements of Arg, Trp, and Thr for 24 h with 6 replicates for each treatment. After 24 h, cells were incubated with fresh culture medium (PC) or 1 mM of H2O2 with different supplements (NC and each treatment) for 6 h. All data were analyzed by ANOVA using the PROC MIXED procedure of SAS (SAS Institute Inc., NC, USA). The replicate was considered an experimental unit. Significance for statistical tests was considered at P < 0.05. The cell viability was less (P < 0.05) in NC treatment than in PC treatment. All treatments of Arg, Trp, and Thr showed greater (P < 0.05) cell viability than NC treatment. Total antioxidant capacity (TAC) was significantly less (P < 0.05) in NC treatment than in PC treatment, whereas 250 μM Arg and 250 μM Trp treatments showed greater (P < 0.05) TAC than NC treatment. Superoxide dismutase activity was significantly greater (P < 0.05) in PC treatment than in other treatments, whereas no significant differences were observed between NC and other treatments. Expression levels of tight junction-related genes including zonula occludens-1 (ZO-1), claudin (CLDN), occludin (OCLN), and junctional adhesion molecule 2 (JAM2) were significantly greater (P < 0.05) in PC treatment than in NC treatment. Among supplemented treatments, 250 μM Arg treatment significantly upregulated ZO-1 expression than in NC treatment. In conclusion, oxidative stress impairs cell viability, antioxidant capacity, and tight junction integrity of cIECs. The 500 μM Thr enhances cell viability, 250 μM Trp increases antioxidant capacity, and 250 μM Arg upregulates ZO-1 gene expression in cIECs.