Interleukin-8 Expression by Human Neutrophils Activated by Water Soluble Proteins of Helicobacter pylori

Song, In Sung; Kim, Chung Yong; Jung, Hyun Chae; Kim, Jung Mogg; Kim, Joo Sung

Abstract

BACKGROUND AND AIMS: Some water soluble proteins released from Helicobacter pylori (H. pylori) may serve as chemoattractants for neutrophils. Once extravasated, neutrophils may be themselves a source of interleukin-8 (IL-8), further amplifying inflammatory response. We evaluated the expression of IL-8 and the activation of human neutrophils by H. pylori products.
METHODS
After human neutrophils were stimulated with H. pylori culture supernatant, the expression of IL-8 mRNA and potein were assessed by quantitative RT- PCR and ELISA for up to 9 hours, respectively. Neutrophil adhesion capacity was determined by the expression of LFA-1B using flow cytometry and the secretion of myeloperoxidase was measured by ELISA. After acetohydroxamic acid (AHA) and/or N-t-butoxycar-bonyl-methionyl- leucyl-phenylalanine (BOC-MLP) was added, IL-8 ELISA was performed until 9 h after the stimulation. The IL-8 level was determined by ELISA after the administration of urease or fMLP in various concentrations.
RESULTS
The level of IL-8 mRNA in stimulated neutrophils was increased by 16- to 67-folds, compared with the level in unstimulated neutrophils (peaked at 2 hours). The amount of IL-8 protein was markedly increased at 4 hours. H. pylori culture supernatant enhanced the expression of LFA-1B and the secretion of myeloperoxidase. AHA and/or BOC-MLP decreased IL-8 production. After stimulation by urease or fMLP, the level of IL-8 production of neutrophils paralleled the administered dose.
CONCLUSIONS
H. pylori-induced neutrophil recruitment may be mediated via IL-8 from neutrophils activated by urease and fMLP. This may explain gastric mucosal inflammatory response to the non-invasive organism.