Helicobacter pylori alters n-6 fatty acid metabolism and prostaglandin E₂ synthesis in rat gastric mucosal cells

Authors: Nakaya, Atsuko¹; Wakabayashi, Hiroyuki¹; Imamura, Lisa²; Fukuta, Kanako¹; Makimoto, Shinya¹; Naganuma, Kotaro¹; Orihara, Tadahiro¹; Minemura, Masami¹; Shimizu, Yukihiro¹; Nagasawa, Tetsuro³; Hamazaki, Tomohito³; Watanabe, Akiharu¹

Source: Journal of Gastroenterology and Hepatology, Volume 16, Number 11, November 2001 , pp. 1197-1205(9)

Publisher: Wiley-Blackwell

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Abstract:

Background and Aims:

Little is known about whether Helicobacter pylori infection alters fatty acid metabolism in gastric mucosal cells. By using cultured rat gastric mucosal cells (RGM-1), we investigated the effect of H. pylori broth culture filtrates on this point. Furthermore, our study aimed to find out whether n-6 long chain polyunsaturated fatty acids from linoleic acid are formed in RGM-1 cells. Methods:

Rat gastric mucosal cells were incubated with 10, 20 and 40 μg/mL of linoleic acid or medium alone. Phosphatidylcholine content extracted from whole RGM-1 cells was quantitated by using a densitometer, and its fatty acid composition was analyzed by using gas chromatography. Prostaglandin E₂ concentration in the culture medium was measured by using radioimmunoassay. The expression of cyclooxygenase (COX)-1 and COX-2 was examined by using reverse transcription-polymerase chain reaction. In addition, after incubation with [1-¹⁴C] linoleic acid, radioactivities of both linoleic acid and arachidonic acid components of the PC fraction were counted. The effects of H. pylori broth culture filtrates on PC content, its fatty acid composition and prostaglandin (PG)E₂ synthesis were also assessed. Results:

Linoleic acid addition caused an increase in the composition of arachidonic acid, as well as linoleic acid, and also in PGE₂ concentration. Cyclo-oxygenase-2 expression was induced in RGM-1 cells by the addition of linoleic acid. In addition, [1-¹⁴C] linoleic acid added to the culture medium was converted to [1-¹⁴C] arachidonic acid in RGM-1 cells. Helicobacter pylori broth culture filtrates decreased linoleic acid composition and increased arachidonic acid composition. Moreover, after incubation with H. pylori broth culture filtrates, PGE₂ concentrations were higher than that of the controls. Conclusions:

These findings suggest the presence of fatty acid elongase and Δ⁵- and Δ⁶-desaturases synthesize arachidonic acid from linoleic acid in RGM-1 cells. Thus, H. pylori infection may enhance PGE₂ synthesis and accelerate n-6 fatty acid metabolism in gastric mucosal cells, which could make the gastric mucosal barrier more fragile.

Keywords: fatty acid metabolism; Helicobacter pylori; phosphatidyl choline; prostaglandin E2; rat gastric mucosal cells

Document Type: Research article

DOI: http://dx.doi.org/10.1046/j.1440-1746.2001.02541.x

Affiliations: 1: Third Department of Internal Medicine, Faculty of Medicine, 2: Department of Hygiene and Biochemistry, Faculty of Pharmaceutical Science and 3: Department of Clinical Application, Institute of Natural Medicine, Toyama Medical and Pharmaceutical University, Toyama, Japan

Publication date: 2001-11-01