Steroids mediate resistance to the bactericidal effect of phosphatidylcholines against Helicobacter pylori
Steroids mediate resistance to the bactericidal effect of phosphatidylcholines against Helicobacter pylori
复制标题
DOI：
10.1111/j.1574-6968.2009.01807.x
复制
发表时间：
2009-12-01
影响因子：
2.1
通讯作者：
Hirai, Yoshikazu
中科院分区：
文献类型：
--
作者：
Shimomura, Hirofumi;Hosoda, Kouichi;Hirai, Yoshikazu
幽门螺杆菌可以吸收多种类固醇作为膜脂成分，但它也可以在没有类固醇的情况下存活。因此，对于生物体在生理上依赖类固醇的原因仍有待澄清。在本研究中，我们发现携带亚油酸分子或花生四烯酸分子的磷脂酰胆碱具有杀死不含类固醇的幽门螺杆菌的潜力。磷脂酰胆碱对幽门螺杆菌的杀菌作用是由于磷脂酰胆碱本身的裂解活性，而不是由于不饱和脂肪酸的裂解活性或磷脂酰胆碱的水解所致。与不含类固醇的幽门螺杆菌不同，吸收和糖化游离胆固醇的生物体不受磷脂酰胆碱杀菌作用的影响。同样，没有糖基化就能吸收雌酮的幽门螺杆菌也能抵抗磷脂酰胆碱的杀菌作用。幽门螺杆菌吸收的类固醇存在于外膜和内膜中，而通过吸收类固醇产生的糖基类固醇定位于外膜而不是内膜。这些结果表明，幽门螺杆菌吸收类固醇来加强膜脂屏障，从而对疏水化合物如磷脂酰胆碱的溶菌作用表现出抵抗。
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.