Antimicrobial peptides from human plateletst
Antimicrobial peptides from human plateletst
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DOI：
10.1128/iai.70.12.6524-6533.2002
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发表时间：
2002-12-01
影响因子：
3.1
通讯作者：
Selsted, ME
中科院分区：
文献类型：
--
作者：
Tang, YQ;Yeaman, MR;Selsted, ME
血小板与已知参与抗微生物宿主防御的粒细胞具有结构和功能相似性。为了评价血小板蛋白的潜在抗菌活性，在体外用人凝血酶刺激正常人血小板。通过反相高效液相色谱法将刺激血小板上清液的组分纯化至均一。通过质谱、氨基酸分析和序列测定，对在琼脂扩散抗菌试验中具有对大肠杆菌ML 35抑制活性的纯化肽进行了表征。这些分析能够从人血小板中鉴定出7种凝血酶可释放的抗菌肽：血小板因子4（PF-4）、RANTES、结缔组织激活肽3（CTAP-3）、血小板碱性蛋白、胸腺素β-4（Tbeta-4）、纤维蛋白肽B（FP-B）和纤维蛋白肽A（FP-A）。除FP-A和FP-B外，所有肽也从未刺激的血小板的酸提取物中纯化。进一步测试七种释放的肽的体外抗微生物活性对抗细菌（E.大肠杆菌和金黄色葡萄球菌）和真菌（白色念珠菌和新型隐球菌）。每种肽对至少两种生物体发挥活性。一般来说，肽对细菌比真菌更有效，在酸性pH下活性更大，并且抗微生物活性是剂量依赖性的。与这些观察结果相反，PF-4在杀微生物试验中显示出双峰剂量-反应关系，而Tbeta-4在碱性pH下具有更大的活性。PF-4和CTAP-3在亚致死浓度下对大肠杆菌有协同作用。杆菌总的来说，这些发现表明血小板的直接抗菌作用，因为它们被激活以响应创伤或炎症介质释放肽。
Platelets share structural and functional similarities with granulocytes known to participate in antimicrobial host defense. To evaluate the potential antimicrobial activities of platelet proteins, normal human platelets were stimulated with human thrombin in vitro. Components of the stimulated-platelet supernatants were purified to homogeneity by reversed-phase high-performance liquid chromatography. Purified peptides with inhibitory activity against Escherichia coli ML35 in an agar diffusion antimicrobial assay were characterized by mass spectrometry, amino acid analysis, and sequence determination. These analyses enabled the identification of seven thrombin-releasable antimicrobial peptides from human platelets: platelet factor 4 (PF-4), RANTES, connective tissue activating peptide 3 (CTAP-3), platelet basic protein, thymosin beta-4 (Tbeta-4), fibrinopeptide B (FP-B), and fibrinopeptide A (FP-A). With the exception of FP-A and FP-B, all peptides were also purified from acid extracts of nonstimulated platelets. The in vitro antimicrobial activities of the seven released peptides were further tested against bacteria (E. coli and Staphylococcus aureus) and fungi (Candida albicans and Cryptococcus neoformans). Each peptide exerted activity against at least two organisms. Generally, the peptides were more potent against bacteria than fungi, activity was greater at acidic pHs, and antimicrobial activities were dose dependent. Exceptions to these observations were observed with PF-4, which displayed a bimodal dose-response relationship in microbicidal assays, and Tbeta-4, which had greater activity at alkaline pHs. At concentrations at which they were individually sublethal, PF-4 and CTAP-3 exerted synergistic microbicidal activity against E. coli. Collectively, these findings suggest a direct antimicrobial role for platelets as they are activated to release peptides in response to trauma or mediators of inflammation.