Morphological aspects of the cytotoxic action of Helicobacter pylori

To morphologically investigate the cytotoxic action of Helicobacter pylori on gastric mucosal cells.

Twenty biopsy specimens were obtained from the antrum and greater curvature of the upper body of the stomach, and examined by electron microscopy to elucidate the process of mucus cell injury induced by H. pylori.

Only H. pylori colonies in intimate contact with the mucosal cells caused various cell alterations, including loss of microvilli, mucus depletion, cell membrane injury and degeneration of the cytoplasm. In contrast, H. pylori that were not in contact with the mucosa had no effect on the surface mucus cells.

The results of this study suggested the following mechanism of H. pylori-induced gastric mucosal injury. Intimate contact between H. pylori and the epithelial cell is necessary for cytotoxic action. During the process of cytotoxic action, degradation of the mucous gel layer and the glycocalyx are first caused by the proteolytic enzymes produced by H. pylori. Then the microorganism approaches the surface mucus cell, making intimate contact with the cell surface. Finally, H. pylori adheres directly to the cell membrane, effecting direct action of the toxins on the cell membrane. Subsequently, the degenerative changes induced destroy the cell membrane, resulting in degeneration of the cell itself.