Gastric mucosal barrier: evidence for Helicobacter pylori ingesting gastric surfactant and deriving protection from it.

Ultrastructural examination by electron microscopy has been undertaken on human oxyntic mucosa from biopsy specimens obtained during diagnostic endoscopy from patients in whom infection by Helicobacter pylori was subsequently confirmed. A novel fixation procedure was used that avoided conventional fixatives based upon glutaraldehyde, which can destroy the hydrophobic lining of surfaces such as gastric mucosa. The resulting electron micrographs show densely osmiophilic inclusions of varying sizes in Helicobacter, some of which can be resolved and identified as lamellar bodies and their partially digested states. This finding indicates that Helicobacter may act as an aggressive agent by ingesting a gastric mucosal barrier of gastric surfactant, exposing the surface to attack by acid while simultaneously rendering it less hydrophobic. There is also evidence that Helicobacter pylori avoid their own digestion by coating themselves with essentially the same barrier of gastric surfactant, probably derived from the host. This is a possible explanation for the apparent absence of these bacteria in the duodenum.