2012-08-012024-05-13https://scholars.lib.ntu.edu.tw/handle/123456789/642637摘要：感染性心內膜炎是主要由口腔鏈球菌(S. mutans, S. sanguinis, S. mitis/oralis)及葡萄球菌(S. aureus or S. epidermidis) 在心臟瓣膜上所引起的感染性疾病，通常具有高致死率及高再發率，而感染性心內膜炎的病徵為心臟瓣膜上贅生物的產生，而這種贅生物是由纖維蛋白與血小板的凝塊及在其上形成生物膜的細菌所組成，這樣的構造對於抗生素的治療具有高度的抵抗性，直至目前，臨床上心內膜炎還是予以高劑量且長時間的抗生素治療，但即使治癒，也依然存在著高復發率；而我們實驗室長久以來的目的是探討感染性心內膜炎的分子及免疫致病機轉，並試圖為感染性心內膜炎尋找有效的治療的方法；而在過去四年的基因體計畫中，我們建立了實驗性心內膜炎的大鼠模型，並利用基因質體學及蛋白質體學(二維電泳技術搭配質譜儀分析與核酸微陣列分析)鑑定了在鏈球菌中與感染性心內膜炎致病有關的毒力因子(結果發表於J. Infect Dis. 2009.199:1488–1496 及Mol. Microbiol. 2009; 74:888–902)。我們的結果率先提出一個觀念，証明除了細菌本身以外，宿主本身的因子對於感染性心內膜炎的致病機轉中也扮演重要角色；其中特別的是，不管是在試管內模式或是大鼠試驗中，都證實了血小板是促進細菌生物膜的形成及其抗藥性的重要的宿主因子(J. Infect Dis. 2012; 205:1066-75)；此外，我們初步的結果發現這種細菌與血小板的生物膜構造可以促進浸潤的嗜中性白血球釋放出胞外網狀結構(NETs)，而這種結構可以進一步引起血小板凝集、促進纖維蛋白凝塊的形成及心內膜炎贅生物的發展成熟；因此，在這個計劃中，我們將針對嗜中性白血球胞外網狀結構在感染性心膜炎的角色做研究，我們將探討受細菌與血小板的生物膜構造刺激而形成的嗜中性白血球胞外網狀結構的分子機制，並將鑑定出其中參與的重要宿主因子。這三年計劃的目標為：1. 研究受細菌與血小板的生物膜構造所刺激形成的嗜中性白血球胞外網狀結構的分子機制。2. 鑑定參與在刺激嗜中性白血球胞外網狀結構形成的細菌或/和血小板分子及其在嗜中性白血球表面的接受分子。3. 利用大鼠實驗性心內膜炎模型確定已鑑定的細菌或宿主分子在致病機轉中的角色。在這個計劃中，我們將利用已建立好的試管內的生物膜模型來研究嗜中性白血球胞外網狀結構形成的分子機制，及參與在其中的細菌及宿主分子，並利用大鼠實驗性心內膜炎模型來確定所鑑定出的分子機制及參與在其中的細菌及宿主分子的角色，而由這個計畫所得到的結果未來將可對於感染性心內膜炎的預防及治療提供新的選擇。<br> Abstract: Infective endocarditis (IE) is an infectious disease caused primarily by oral Streptococci(S. mutans, S. sanguinis, S. mitis/oralis), or Staphylococci (S. aureus or S. epidermidis) on theheart valves, with high mortality and recurrent rates. Histopathologically, IE is characterizedby the formation of vegetations, fibrin-platelet clots with the embedded bacteria formingbiofilm, which is refractory to routine antibiotic treatment. Until now, clinical management ofIE still demands long-lasting and high dose of antibiotic treatment, but possessing highrecurrent rates. The long-term goal of our laboratory is to elucidate the molecular- andimmuno-pathogenesis of IE and search for the therapeutic molecules for IE. During the past 4years of genomic projects, we have established a rat model of experimental endocarditis andidentified essential virulence factors in Streptococci for inducing IE by proteomic andgenomic approaches (2-DE coupled with MS analysis and microarray) (J. Infect Dis. 2009;199:1488–1496; Mol. Microbiol. 2009; 74:888–902). Our pioneering results also lead to thenotion that host factors play important roles in the pathogenesis of IE. Specifically, platelet isan essential host factor for Streptococci to enhance bacterial biofilm formation and resistancein vitro and in vivo (J. Infect Dis. 2012; 205:1066-75). In addition, our preliminary data showthat the bacteria-platelet biofilm can induce the extracellular DNA secretion from theinfiltrated neutrophils (named neutrophil extracellular traps; NETs) and the NETs couldfurther induce the platelet aggregation, fibrin-clot formation and vegetation maturation.Therefore, in this project, we will focus specifically on the role of NETs in IE. We willelucidate the molecular mechanisms of NET formation induced by the bacteria-plateletbiofilm and will identify the key host factors involved in the NETs formation. The specificaims of this three-year project will be1. Investigation of the underlying mechanisms of neutrophil NETs formation induced bythe bacteria-platelet biofilm2. Identification of bacterial or/and platelet components responsible for inducing neutrophilNETs formation and their receptors on the neutrophil surface3. Confirm the role of the identified bacterial or/and host components in the pathogenesis ina rat experimental endocarditisIn this project, we will investigate the underlying mechanisms of neutrophil NETsformation and identify the bacterial or/and host components in the well-established in-vitroNETs-containing bacteria-platelet biofilm model, and confirmed these identifiedmechanisms or bacterial or/and host components in the in-vivo rat experimental IE model.Results obtained from this study could offer new strategies for the clinical prevention andtherapy for IE.感染性心內膜炎生物膜細菌血小板交互作用嗜中性白血球胞外網狀結構Infective endocarditisbiofilmthe interaction of bacteria and plateletneutrophilextracellular traps (NETs)