Steroids mediate resistance to the bactericidal effect of phosphatidylcholines against Helicobacter pylori.
Helicobacter pylori assimilates various steroids as membrane lipid components, but it can also survive in the absence of steroids. It thus remains to be clarified as to why the organism relies on steroid physiologically. In this study, we have found that phosphatidylcholine carrying a linoleic acid molecule or arachidonic acid molecule has the potential to kill steroid-free H. pylori. The bactericidal action of phosphatidylcholines against H. pylori was due to the lytic activity of the phosphatidylcholines themselves and not due to the lytic activity of the unsaturated fatty acids or lyso-phosphatidylcholine resulting from the hydrolysis of the phosphatidylcholines. In contrast to the steroid-free H. pylori, the organism that absorbed and glucosylated free cholesterol was unaffected by the bactericidal action of the phosphatidylcholines. Similarly, H. pylori that absorbed estrone without glucosylating it also resisted the bactericidal action of the phosphatidylcholines. The steroids absorbed by H. pylori existed in both the outer and inner membranes, while the glucosyl-steroids produced via the steroid absorption were localized in the outer membrane rather than in the inner membrane. These results indicate that H. pylori absorbs the steroids to reinforce the membrane lipid barrier and thereby expresses resistance to the bacteriolytic action of hydrophobic compounds such as phosphatidylcholine.
Shimomura
Hirofumi
H
Department of Infection and Immunity, Division of Bacteriology, Jichi Medical University, Tochigi, Japan. shimo@jichi.ac.jp
Hosoda
Kouichi
K
Hayashi
Shunji
S
Yokota
Kenji
K
Oguma
Keiji
K
Hirai
Yoshikazu
Y
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016718:Arachidonic Acid / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism*; D024881:Drug Resistance, Bacterial; D004970:Estrone / Q000378:metabolism*; D006027:Glycosides / Q000378:metabolism; D016481:Helicobacter Infections / Q000188:drug therapy / Q000378:metabolism / Q000382:microbiology; D016480:Helicobacter pylori / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D054884:Host-Pathogen Interactions; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D019787:Linoleic Acid / Q000378:metabolism; D008826:Microbial Sensitivity Tests; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D006027:Glycosides; D010713:Phosphatidylcholines; D016718:Arachidonic Acid; D004970:Estrone; D002784:Cholesterol; D019787:Linoleic Acid