KILLING OF GRAM-NEGATIVE BACTERIA BY LACTOFERRIN AND LYSOZYME
KILLING OF GRAM-NEGATIVE BACTERIA BY LACTOFERRIN AND LYSOZYME
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DOI：
10.1172/jci115407
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发表时间：
1991-10-01
影响因子：
15.9
通讯作者：
GIEHL, TJ
中科院分区：
文献类型：
--
作者：
ELLISON, RT;GIEHL, TJ
尽管乳铁蛋白具有抗菌活性，但其作用机制尚未完全明确。 最近我们发现该蛋白质改变了革兰氏阴性菌的外膜。 由于这种膜可以保护革兰氏阴性细胞免受溶菌酶的侵害，因此我们研究了乳铁蛋白的膜效应是否可以增强溶菌酶的抗菌活性。 我们发现，虽然每种蛋白质单独具有抑菌作用，但它们一起可以对霍乱弧菌、鼠伤寒沙门氏菌和大肠杆菌菌株具有杀菌作用。 杀菌作用是剂量依赖性的，被乳铁蛋白的铁饱和所阻断，并被高钙水平所抑制，尽管乳铁蛋白不螯合钙。 使用不同的培养基，可以部分或完全抑制乳铁蛋白和溶菌酶的作用；抑制程度与介质渗透压相关。 透射电子显微镜显示，暴露于 40 mOsm 的乳铁蛋白和溶菌酶的大肠杆菌细胞变得增大且密度降低，表明通过渗透损伤而被杀死。 透析室研究表明，杀灭细菌需要与乳铁蛋白直接接触，而使用纯化的 LPS 表明这与蛋白质直接与 LPS 结合有关。 由于乳铁蛋白和溶菌酶在粘膜分泌物和中性粒细胞颗粒中以高水平同时存在，因此它们的相互作用可能有助于宿主防御。
Although lactoferrin has antimicrobial activity, its mechanism of action is not fully defined. Recently we have shown that the protein alters the Gram-negative outer membrane. As this membrane protects Gram-negative cells from lysozyme, we have studied whether lactoferrin's membrane effect could enhance the antibacterial activity of lysozyme. We have found that while each protein alone is bacteriostatic, together they can be bactericidal for strains of V. cholerae, S. typhimurium, and E. coli. The bactericidal effect is dose dependent, blocked by iron saturation of lactoferrin, and inhibited by high calcium levels, although lactoferrin does not chelate calcium. Using differing media, the effect of lactoferrin and lysozyme can be partially or completely inhibited; the degree of inhibition correlating with media osmolarity. Transmission electron microscopy shows that E. coli cells exposed to lactoferrin and lysozyme at 40 mOsm become enlarged and hypodense, suggesting killing through osmotic damage. Dialysis chamber studies indicate that bacterial killing requires direct contact with lactoferrin, and work with purified LPS suggests that this relates to direct LPS-binding by the protein. As lactoferrin and lysozyme are present together in high levels in mucosal secretions and neutrophil granules, it is probable that their interaction contributes to host defense.