5-LOX inhibitor modulates the inflammatory responses provoked by Helicobacter pylori infection.
BACKGROUND
Arachidonic acid metabolites have been considered as pivotal mediators in Helicobacter pylori-induced inflammatory response, which are mainly metabolized by two distinct enzymes: cyclooxygenase (COX) and lipoxygenase (LOX). While COX has become well known to play a key role in either carcinogenesis or inflammation related to H. pylori infection, little is known regarding the implication of LOX in H. pylori infection. In this study, we evaluated the roles of 5-LOX and its metabolites in H. pylori-induced host responses and further a potential beneficial action of specific LOX inhibitors against H. pylori infection.


METHODS
Expressions of cytosolic phospholipase A(2) (cPLA(2)), COX-2, and 5-LOX after H. pylori infection were evaluated by immunofluorescence staining and Western blotting. Synthesis of LOX metabolites was measured with reversed-phase high-performance liquid chromatography. For analyzing the influence of 5-LOX inhibitors, nordihydroguaiaretic acid (NDGA) and geraniin, on H. pylori-induced inflammatory responses, RNase protection assay and RT-PCR were performed.


RESULTS
H. pylori stimulated the translocation of cPLA(2) from cytoplasm to nucleus and increased the biosynthesis of hydroxyeicosatetraenoic acids (HETEs) as a predominant form of 5S-HETE in gastric epithelium. NDGA exerted a strong suppression activity of H. pylori-induced 5-LOX signaling. The administration of LOX inhibitors was related with down-expression of proinflammatory mediators such as interleukin-8 and tumor necrosis factor-alpha in both H. pylori-infected gastric epithelial cells and macrophage cells.


CONCLUSIONS
LOX modulation with its specific inhibitors could impose significant anti-inflammatory responses after H. pylori infection, based on the fact that H. pylori infection provoked gastric inflammation through metabolizing arachidonic acid by the 5-LOX pathway.
Park
Soojin
S
Genomic Research Center for Gastroenterology, Ajou University School of Medicine, Suwon, Bundang Jesaeng Hospital, Seongnam, Korea.
Han
Sang-Uk
SU
Lee
Kee-Myung
KM
Park
Kyung Ha
KH
Cho
Sung Won
SW
Hahm
Ki-Baik
KB
D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D016718:Arachidonic Acid / Q000378:metabolism*; D002460:Cell Line; D015536:Down-Regulation; D004847:Epithelial Cells / Q000378:metabolism / Q000382:microbiology; D005960:Glucosides / Q000494:pharmacology; D016481:Helicobacter Infections / Q000378:metabolism*; D016480:Helicobacter pylori; D006801:Humans; D047348:Hydrolyzable Tannins / Q000494:pharmacology; D016209:Interleukin-8 / Q000378:metabolism; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology; D008264:Macrophages / Q000378:metabolism / Q000382:microbiology; D009637:Masoprocol / Q000494:pharmacology*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D005960:Glucosides; D047348:Hydrolyzable Tannins; D016209:Interleukin-8; D016859:Lipoxygenase Inhibitors; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D016718:Arachidonic Acid; C024603:Geraniin; D009637:Masoprocol; D001094:Arachidonate 5-Lipoxygenase; D048052:Mitogen-Activated Protein Kinase 3