Toll-like receptor 2-mediated gene expression in epithelial cells during Helicobacter pylori infection

Helicobacter pylori is the major pathogen causing chronic gastritis and peptic ulcer disease and is closely linked to gastric malignancy. We have previously shown that H. pylori-induced NF-(kappa)B activation and interleukin (IL)-8 secretion are mediated by Toll-like receptor (TLR) 2 in epithelial cells. However, the TLR2-mediated global gene expression profile of the epithelial cell during H. pylori infection is still unknown. The goal of this study was to identify TLR2-regulated genes in epithelial cells induced by H. pylori.

The HEK293 and HEK-TLR2 cells were cocultured with H. pylori 26695 for 6 hours. Total RNA was extracted and hybridized to the Affymetrix human U133A microarray chipset, which contains 22,283 total probe sets including 14,285 genes. Data analyses were performed using affymetrix suite 5 software. The expression of selected genes in gastric epithelial cells AGS and MKN45 was monitored by quantitative reverse transcriptase-polymerase chain reaction (RT-PCR).

Forty-six genes, contained in 57 probe sets, were induced > 2-fold and three genes (five probe sets) decreased > 2-fold by H. pylori infection of HEK293 cells. Fifty-four genes, contained in 69 probe sets, were induced > 2-fold, whereas only 1 gene was repressed > 2-fold in H. pylori-infected HEK-TLR2 cells. Comparisons of genes induced in HEK293 or HEK-TLR2 cells identified 28 genes whose expression was dependent on the presence of TLR2. Seventeen genes were selected and their expression was assessed using the quantitative RT-PCR in gastric epithelial cells during H. pylori infection. Eight of the 17 genes showed distinct expression patterns in AGS and MKN45 cells after H. pylori stimulation.

The current study investigated the TLR2-mediated global gene changes after H. pylori stimulation in the epithelial cell system. This approach will be helpful in identifying genes whose expression is mediated by specific TLRs and in determining the cellular responses that are responsible for diverse signal pathways during H. pylori infection.