S1767 NOD1 is Essential Signal Transducer in Human Gastric Epithelial Cells Infected With Helicobacter pylori

Abstract

BACKGROUND/AIM Nucleotide binding oligomerization domain (Nod) proteins are members of a family that includes the apoptosis regulator APAF1. Nod proteins have been implicated in the induction of NF-κB activity and in the activation of caspases. Helicobacter pylori (H. pylori) infection is reported to express TLR 4, TLR-5 and TLR-9 in gastric epithelial cells. However, TLR-4 and TLR-5 are not recognized as important role in H. pylori infection. This implicated that another signal transducer different from TLR pathway may affect NFκB activation in cag PAI (+) H. pylori infection. The purpose of this study was to investigate whether cag PAI (+) H. pylori infection affects NF-κB activation and IL-8 production through Nod1 and to evaluate the transepithelial neutrophil migration induced by H. pylori infection. METHODS Stable transfection of Dominant Negative (DN) Nod1 in AGS cell line was established followed by NF-κB activation and IL-8 production by H. pylori HP 99 infection was assessed. The role of cag PAI was examined comparing wild type H. pylori strain with cag PAI knock-down CagAand CagEH. pylori strain. To assess the production of IL-8, we examined mRNA expression using RT-PCR, and IL-8 secretion using ELISA. To assess the inhibition of NF-κB activation, we examined degradation and phosphorylation of IκBα using western blot and EMSA. To examine the role of cag PAI, we examined the production of IL-8 and the inhibition of NF-κB activation in the cag PAI knock-down CagAand CagEH. pylori infection in the same manner with wild type. We established the neutrophil migration model induced by H. pylori infection in polarized DN Nod1 Caco-2 cell line and evaluated transepithelial neutrophil migration as to the cag PAI status. RESULTS Stable transfection of DN Nod1 followed by cag PAI (+) H. pylori inhibited IL-8 mRNA expression and IL-8 production. In addition, cag PAI (+) H. pylori inhibited IκB-α degradation and IκB-α phosphorylation. IL-8 mRNA expression and IL-8 production by CagA-and CagEH. pylori were significantly decreased compared with those by wild type H. pylori. IκB-α degradation and IκB-α phosphorylation by CagA-and CagEH. pylori were significantly decreased compared with those by wild type H. pylori. NF-κB expression by CagA-and CagEH. pylori was significantly decreased compared with that by wild type H. pylori. Transepithelial neutrophil migration was more prominent in wild type H. pylori than CagAand CagEH. pylori CONCLUSION Signaling through Nod1 plays an essential role in the upregulated expression of IL-8 in human epithelial cells infected with H. pylori.