二价金属铁离子（Fe^（＋＋））在体内和体外对阴道滴虫蛋白表达的调控

THE DIVALENT IRON CATION (Fe￣■) REGULATES PROTEIN EXPRESSION OF TRICHOMONAS VAGINALIS IN VITRO AND IN VIVO

阴道滴虫是世界范围的性传染的阴道滴虫病的病原体。病原微生物在机体内生存，不仅要逃避宿主的免疫反应，而且还要能获得其生存所必需的生长因子。金属铁离子（Ｆｅ^（＋＋））是关系到阴道滴虫能否正常生长的必需因子之一。先前的工作已证明，在离体条件下，高铁离子环境促进滴虫吸附到Ｈｅｌａ细胞上。本文主要研究在体内和体外条件下，滴虫是如何在蛋白质表达水平上对环境中铁离子浓度高低作出反应。这里观察到至少３个铁诱导蛋白和两个铁抑制蛋白。其中分子量为１３６ｋＤ的蛋白是以前报道的乳铁蛋白受体。也研究了环境ｐＨ对于这些铁调节蛋白的影响。结果表明：在所研究的ｐＨ５．０～６．４范围内，虽然较低的ｐＨ环境促进滴虫细胞的增殖，但并不明显地影响铁离子对铁调节蛋白的调控。通过使用阴道滴虫病患者的血清进行放射免疫沉淀实验，间接证明铁离子不仅在体外，而且可能也在体内调节这些铁调节蛋白的表达。环境铁离子在体内调节滴虫蛋白表达这一事实在国内外鲜有报道。尚需做进一步研究才能全面理解铁离子调控滴虫蛋白的分子机制和水平。

Trichomonas vaginalis is a flagellated protozoan responsible for a world-wide sexually transmitted disease-trichomoniasis. Pathogenic bacteria must not only evade host defences but also successfully compete for nutrients. Iron (Fe()) is one of the most required nutrients for the survival of T,vaginalis. Our previous work indicated that in vitro a high-iron environment promoted adherence of trichomonas to Hela eells. The current paper examines trichomonad responses at the level of protein expression to high and low concentrations of iron (Fe()) in vitro and in vivo. It was found that environmental iron induced expression of at least three trichomonad proteins and repressed expression of two proteins. One of the iron-repressed proteins with a relative molecular weight of 136kD was previously reported by our laboratory as a lactoferrin-binding receptor. The effect of environmental pH on the expression of trichomonad iron-regulated proteins was also investigated. Within the pH range tested (pH 5.0-6.4), there was no effect on the iron regulated proteins. However, the lower pH values stimulated the growth rate of T. vaginalis. Using anti-sera of patients with trichomoniasis, our radioimmunoprecipitations suggested that environmental iron regulate expression of the trichomonad proteins not only in vitro, but also in vivo. This finding further confirmes our privious observation that environmental iron regulates expression of trichomonad proteins in an in vivo svstem, Further studies are needed to understand the molecular mechanisms which control the iron-regulated expression of trichomonad proteins.