Helicobacter pylori-induced gastric inflammation and gastric cancer

Helicobacter pylori (H. pylori) infect over half of the world's population. The prevalence of H. pylori infection and the predominant genotype of H. pylori virulence factors vary considerably across different geographical regions. H. pylori could uniquely persist for decades in the harsh stomach environment, where it damages the gastric mucosa and changes the pattern of gastric hormone release, thereby affects gastric physiology. By utilizing various virulence factors, H. pylori targets different cellular proteins to modulate the host inflammatory response and initiate multiple "hits" on the gastric mucosa, resulting in chronic gastritis and peptic ulceration. Among the long-term consequences of H. pylori infection is gastric malignancies, particularly gastric cancer (GC) and gastric mucosa-associated lymphoid tissue (MALT) lymphoma. As such, H. pylori has been recognized as a class I carcinogen by the International Agency for Research on Cancer. Despite a close causal link between H. pylori infection and the development of gastric malignancies, the precise mechanisms involved in this process are still obscure. Studies over the past two decades have revealed that H. pylori exert oncogenic effects on gastric mucosa through a complex interaction between bacterial factors, host factors, and environmental factors. Numerous signaling pathways can be activated by H. pylori. In this review, we aim to elaborate on the recent developments in the pathophysiological mechanisms of H. pylori-induced gastric inflammation and gastric cancer.