Activation of human phagocyte oxidative metabolism by Helicobacter pylori

Area of Science:

• Immunology
• Gastroenterology
• Microbiology

Background:

• Chronic antral gastritis involves significant inflammation linked to Helicobacter pylori.
• The precise mechanisms of tissue damage in H. pylori-associated gastritis remain unclear.
• Reactive oxygen radicals are known contributors to tissue damage in inflammatory conditions.

Purpose of the Study:

• To investigate the effect of H. pylori sonicate on the oxidative burst response of human phagocytes.
• To determine if H. pylori components can prime immune cells for enhanced reactive oxygen radical production.
• To characterize the nature of the H. pylori-induced stimulatory activity.

Main Methods:

• Human polymorphonuclear leukocytes and monocytes were exposed to H. pylori sonicate.
• Chemiluminescence assays were used to measure oxidative burst responsiveness.
• Cells were preincubated with sonicate and then stimulated with N-f-methionyl-leucyl-phenylalanine and phorbol-myristate-acetate.
• Biochemical treatments including dialysis, proteinase digestion, and heat treatment were employed to characterize the active component.

Main Results:

• H. pylori sonicate dose-dependently stimulated reactive oxygen radical production in both leukocytes and monocytes.
• Preincubation with sonicate primed cells, enhancing their response to subsequent stimuli.
• The stimulatory activity was nondialysable, destroyed by proteinase, and heat-resistant but reduced by dialysis of boiled sonicate.
• Preliminary data suggest the active component is a protein of 25-35 kilodaltons.

Conclusions:

• H. pylori sonicate contains a protein component that stimulates reactive oxygen radical production by human phagocytes.
• This finding provides insight into the immunopathological mechanisms underlying tissue damage in H. pylori infections.
• The identified protein may play a significant role in the inflammatory processes of chronic gastritis.