In Vivo Expression of Helicobacter pylori Virulence Genes in Patients with Gastritis, Ulcer, and Gastric Cancer

Abstract

The best-studied Helicobacter pylori virulence factor associated with development of peptic ulcer disease or gastric cancer (GC) rather than asymptomatic nonatrophic gastritis (NAG) is the cag pathogenicity island (cagPAI), which encodes a type IV secretion system (T4SS) that injects the CagA oncoprotein into host epithelial cells. Here we used real-time reverse transcription-PCR (RT-PCR) to measure the in vivo expression of genes on the cagPAI and of other virulence genes in patients with NAG, duodenal ulcer (DU), or GC. In vivo expression of H. pylori virulence genes was greater overall in gastric biopsy specimens of patients with GC than in those of patients with NAG or DU. However, since in vitro expression of cagA was not greater in H. pylori strains from patients with GC than in those from patients with NAG or DU, increased expression in GC in vivo is likely a result of environmental conditions in the gastric mucosa, though it may in turn cause more severe pathology. Increased expression of virulence genes in GC may represent a stress response to elevated pH or other environmental conditions in the stomach of patients with GC, which may be less hospitable to H. pylori colonization than the acidic environment in patients with NAG or DU.

Helicobacter pylori Antigen HP0986 (TieA) Interacts with Cultured Gastric Epithelial Cells and Induces IL8 Secretion via NF‐κB Mediated Pathway

“…. It was also shown that in vivo expression of CagA in gastric biopsies was lower than its in vitro expression which was further consistent with a DNA microarray study wherein the in vivo CagA expression was downregulated by low pH levels .…”

Helicobacter pylori vacAtranscription is genetically-determined and stratifies the level of human gastric inflammation and atrophy

“…A recent study found vacA expression to be higher in patients with gastric cancer than in those with non-atrophic gastritis or duodenal ulcer 25. This agrees with our finding that higher vacA expression in the gastric mucosa is associated with increased inflammation and the presence of atrophy.…”

CXC chemokine CXCL12 tissue expression and circulating levels in peptic ulcer patients with Helicobacter pylori infection

“…Helicobacter pylori infection is found in approximately 50% of the world's population and provokes chronic inflammation which can further cause peptic ulcer disease (10-15%) and gastric cancer (1-3%) [1]. Recently, H. pylori infection has been found to be a major risk factor for peptic ulcer disease (PUD), including gastric and duodenal ulcers [2].…”