N-acetylcysteine reduces inflammation in the small intestine by regulating redox, EGF and TLR4 signaling

This study determined whether N-acetylcysteine (NAC) could affect intestinal redox status, proinflammatory cytokines, epidermal growth factor (EGF), EGF receptor (EGFR), Toll-like receptor-4 (TLR4), and aquaporin-8 in a lipopolysaccharide (LPS)-challenged piglet model. Eighteen piglets (35-day-old) were randomly allocated into one of the three treatments (control, LPS and NAC). The control and LPS groups were fed a basal diet, and the NAC group received the basal diet +500 mg/kg NAC. On days 10, 13, and 20 of the trial, the LPS- and NAC-treated piglets received intraperitoneal administration of LPS (100 mu g/kg BW), whereas the control group received the same volume of saline. On days 10 and 20, venous blood samples were obtained at 3 h post LPS or saline injection. On day 21 of the trial, piglets were killed to obtain the intestinal mucosa for analysis. Compared with the control group, LPS challenge reduced (P < 0.05) the activities of superoxide dismutase, catalase, and glutathione peroxidase in jejunal mucosae, while increasing (P < 0.05) the concentrations of malondialdehyde, H2O2, O-2 (center dot-) and the ratio of oxidized to reduced glutathione in jejunal mucosae, and concentrations of TNF-alpha, cortisol, interleukin-6, and prostaglandin E-2 in both plasma and intestinal mucosae. These adverse effects of LPS were attenuated (P < 0.05) by NAC supplementation. Moreover, NAC prevented LPS-induced increases in abundances of intestinal HSP70 and NF-kappa B p65 proteins and TLR4 mRNA. NAC supplementation enhanced plasma EGF concentration and intestinal EGFR mRNA levels. Collectively, these results indicate that dietary NAC supplementation alleviates LPS-induced intestinal inflammation via regulating redox, EGF, and TLR4 signaling.