Helicobacter Pylori

Helicobacter pylori is a Gram negative bacteria which colonizes in the human stomach and stimulates gastric mucosal inflammations leading to acute gastritis-associated diseases among them are atrophic gastritis, peptic ulcer and gastric cancer.

H. pylori is found in half of the world’s population and is defined as a group I carcinogens. .

An important virulence factor of H. pylori is Cytotoxin-associated gene A (CagA) which is located at the end of an approximately 40-kb cluster of genes called cag pathoge¬nicity island (PAI).

Cag PAI encodes a type-IV secretion system and transfers CagA protein into the intracellular region of gastric epithelial cell.

This relocation induces cellular hyper proliferation, apoptosis and leading to failure of gastric epithelial cell in maintaining its normal cytoskeletal structure. Furthermore it increases the secretion of cytokines such as tumor necrosis factor (TNF) and interleukin (IL) 1, 6 and 8 by the epithelial cells.

The IL-8 leads to extreme inflammatory responses and also stimulates the production of oxygen free radicals that could cause DNA damage to adjacent cells and lead to genetic modifications of gastric epithelial cells which are carcinogenic.

Helicobacter pylori, a Gram-negative, microaerophilic bacterium that populates in the stomach, predominantly at the antrum. Helicobacter pylori causes a chronic inflammation of the mucoid lining of stomach and is highly related to the growth of duodenal and gastric ulcers and stomach cancer. Over 50% of the world's population harbor H. pylori in their upper gastrointestinal tract, infection is more prevalent in developing countries. Thus far, no ideal target H. pylori antigen has been developed for the diagnostic purpose. 23 kDa H. pylori outer membrane protein was identified with a good sensitivity and coverage in the diagnosis of H. pylori infection.

HP-NAP protects DNA from oxidative damage by sequestering intracellular Fe2+ ion and storing it in the form of Fe3+ oxyhydroxide mineral. One hydrogen peroxide oxidizes two Fe2+ ions, thus preventing hydroxyl radical production by the Fenton reaction. HP-NAP is necessary for the survival in the presence of oxidative stress. Dps is also a virulence factor which activates neutrophils, mast cells and monocytes. HP-NAP binds to neutrophil-glycosphingolipids and to sulfated carbohydrates on mucin. HP-NAP might play a part in the accumulation of neutrophils and monocytes at the site of infection. HP-NAP induces superoxide anion generation, adhesion and chemotaxis of neutrophils, via a pertussis toxin-sensitive pathway involving MAP kinases.