N-3 Polyunsaturated Fatty Acids Protect Esophageal Epithelial Cell From Acid Exposure

Abstract

Abstract Objectives Our previous study has found that n-3 polyunsaturated fatty acids (PUFAs) inhibited inflammation in rats with esophagitis. This study was aimed to observe the protective effect of n-3 PUFAs on esophageal epithelial cells against acid damage and to explore its mechanism. Methods Human esophageal epithelial cells (Het-1A) were repeatedly treated with acidified medium (pH 5.0) and PUFAs with different ratios of n-6/n-3 (9:1, 3:1, 1:1 and 1:3, respectively), and Nrf2 agonists or inhibitors were used to assess the role of Nrf2 in mechanism of n-3 PUFAs. Western Blot and Quantitative Real-time PCR (qPCR) were used to assess the expression of Nrf2, NLRP3 and caspase-1. IL-1β, IL-18 and LDH levels in cell culture supernatants were detected by enzyme linked immunosorbent assay (ELISA), while pyroptosis was assessed by caspase-1 and TUNEL double staining. Results Compared with the normal group, the level of MDA was increased after acid intervention, while that of SOD was decreased (P < 0.05). In groups with different ratios of n-6/n-3 PUFAs, the expressions of Nrf2 and SOD were increased along with the increasing of n-3 PUFAS ratio, which was reached the highest at 1:1 (P < 0.05) and was followed by a decrease. Compared with the 9:1 group, the expression of NLRP3, caspase-1 and the pyroptosis rate of 1:1 group were decreased (P < 0.05). IL-1β, IL-18, and LDH levels in the cell culture supernatant were also decreased in 1:1 group (P < 0.05). Among Nrf2 agonist group, inhibitor group, control group and solvent group, the expression of Nrf2 was highest while the expressions of NLRP3, caspase-1 and pyroptosis rate were lowest in the agonist group (P < 0.05). In the inhibitor group, the expression of Nrf2 was lowest and pyroptosis related protein as well as pyroptosis rate were highest (P < 0.05). There was no significant difference in all indexes between control and solvent group (P > 0.05). Conclusions N-3 PUFAs protected esophageal epithelial cells from acid damage through upregulating Nrf2, which therefore disrupted oxidative stress and NLRP3 inflammasome activation, and then resulted in pyroptosis inhibition. Funding Sources This study was supported by the Science Foundation of the Fujian Province, China(Grant No. 2019J01447).