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首页> 外文期刊>Infection and immunity >Purification and in vitro activities of rabbit platelet microbicidal proteins.
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Purification and in vitro activities of rabbit platelet microbicidal proteins.

机译：兔血小板杀微生物蛋白的纯化和体外活性。

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Recent in vitro studies have demonstrated that rabbit platelets release a small, cationic antimicrobial protein in response to thrombin stimulation under physiological conditions (M. R. Yeaman, S. M. Puentes, D. C. Norman, and A. S. Bayer, Infect. Immun. 60:1202-1209, 1992). This observation prompted our present investigation, focused on determining the array of antimicrobial proteins contained within rabbit platelets and their in vitro activity against common bloodstream pathogens. A group of small (6.0- to 9.0-kDa), cationic proteins with in vitro antimicrobial activity was purified from whole and thrombin-stimulated rabbit platelets by gel filtration and reversed-phase high-performance liquid chromatography. Purified proteins in micromolar concentrations (10 to 40 microg/ml) exerted in vitro microbiostatic and/or microbicidal activities against Staphylococcus aureus, Escherichia coli, and Candida albicans in a dose-dependent manner. The antimicrobial activities of proteins purified from rabbit platelet acid extracts were generally inversely related to pH, with maximal activity observed at pH 5.5. In contrast, the predominant protein isolated from thrombin-stimulated rabbit platelets, though biochemically and microbiologically similar to proteins extracted by acid, exhibited antimicrobial activities which were modestly enhanced at pH 7.2 compared with pH 5.5. Amino acid compositional analyses in combination with molecular mass determinations suggest that the majority of these proteins are distinct molecules not derived from a single common precursor. Collectively, these data indicate that rabbit platelets contain proteins which exert potent in vitro antimicrobial activity against bacterial and fungal pathogens which commonly invade the bloodstream. Moreover, several of these proteins were released from platelets stimulated with thrombin under physiological conditions and exerted potent antimicrobial activities in physiological pH ranges. These observations support the hypothesis that platelets serve an important role in host defense against infection, via localized release of antimicrobial proteins in response to stimuli associated with tissue injury or microbial colonization.
机译：最近的体外研究表明，在生理条件下，兔血小板响应凝血酶刺激而释放出一种小的阳离子抗微生物蛋白（MR Yeaman，SM Puentes，DC Norman和AS Bayer，Infect。Immun。60：1202-1209，1992）。 。这一发现促使我们进行了当前的研究，重点是确定兔血小板中所含的抗菌蛋白的阵列及其对常见血流病原体的体外活性。通过凝胶过滤和反相高效液相色谱法，从完整的凝血酶刺激的兔血小板中纯化出一组具有体外抗菌活性的小（6.0-9.0kDa）阳离子蛋白。以微摩尔浓度（10至40微克/毫升）纯化的蛋白质对金黄色葡萄球菌，大肠埃希氏菌和白色念珠菌具有体外抑菌和/或杀菌活性。从兔血小板酸提取物中纯化的蛋白质的抗菌活性通常与pH呈反相关，在pH 5.5时观察到最大的活性。相反，从凝血酶刺激的兔血小板中分离出的主要蛋白质，尽管在生化和微生物学上类似于酸提取的蛋白质，但其抗菌活性在pH 7.2时比pH 5.5有所提高。氨基酸组成分析与分子量测定相结合表明，这些蛋白质中的大多数是不衍生自单个共同前体的独特分子。总的来说，这些数据表明，兔血小板含有的蛋白质具有对通常侵入血流的细菌和真菌病原体发挥有效的体外抗菌活性的能力。此外，这些蛋白中的几种是在生理条件下从凝血酶刺激的血小板中释放出来的，并在生理pH范围内发挥了强大的抗菌活性。这些观察结果支持以下假设：血小板通过响应与组织损伤或微生物定植相关的刺激而局部释放抗菌蛋白，在宿主抵抗感染中起重要作用。

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