TRAUMA, INFECTION, AND PROSTHETIC BIOMATERIALS

以生物材料为中心的感染是导致手术失败的重要原因 假体植入物和器官。几乎所有这类感染，早期和 晚期，发生在假体周围间隙，由低水平的 手术时植入的微生物造成的污染。这个 宿主不能清除相对较少的细菌很可能是 由于在中性粒细胞存在的情况下，中性粒细胞未能氧化杀死 异物。在之前的拨款中，我们已经仔细研究过了 期间，中性粒细胞呼吸爆发之间的直接相互作用 以及各种生物材料。我们和其他人的证据支持 吸附在特定聚合物上的蛋白质与特定蛋白质结合的观点 中性粒细胞上的受体，并使其产生过量的 被污染触发时的活性氧中间体(ROI) 细菌制品(葡萄球菌或脂多糖)或炎症性 像肿瘤坏死因子这样的细胞因子。由于过度的 ROI的产生，中性粒细胞很可能在他们的 杀死细菌的能力。支持这一想法的是这样一个事实： 吸附的蛋白质不仅可以结合和激发中性粒细胞，而且它们 还可以专门结合(调理)细菌和细菌产品。 这些蛋白质包括血浆蛋白(纤维蛋白原)、细胞外 基质蛋白(纤维连接蛋白、层粘连蛋白)，血小板衍生蛋白 (凝血酶敏感蛋白)和脂多糖结合蛋白(LBP)。这个 假体表面会成为感染的平台，因为它 吸附将细菌和中性粒细胞结合在一起的蛋白质 导致大量和长时间ROI生产的配置 这反过来又降低了氧化杀戮的水平。此外，这样的一个 复杂的生物材料/蛋白质/细菌表面可能会刺激 巨噬细胞：1)分泌细胞因子，下调吞噬功能 杀戮；2)分泌具有反应能力的一氧化氮 和淬灭杀灭细菌所需的投资回报率。目前的建议 旨在系统地阐明几个 选定的生物材料和可疑的光学蛋白以确定 这些蛋白质如何与生物材料结合，以及这些复合体如何固定细菌 到聚合物表面。一旦事情变得明朗起来，某些光学技术 蛋白质可以被吸附到生物材料上，并在那里结合细菌， 生物材料/蛋白质/细菌复合体对中性粒细胞和 可以测定巨噬细胞的反应。最终的目标是更多 完全了解这些相互作用对 在人工植入物存在的情况下氧化杀灭细菌。

Biomaterial centered infection is an important cause of the failure of prosthetic implants and organs. Almost all such infections, early and late, occur in the periprosthetic space and are caused by low levels of contamination with microbes implanted at the time of surgery. The inability of the host to eliminate relatively few bacteria is most likely due to failure of oxidative killing by the neutrophil in the presence of the foreign body. We have carefully explored, in the previous grant period, the direct interactions between neutrophilic respiratory burst and various biomaterials. Our evidence and that of others supports the idea that proteins adsorbed to certain polymers bind to specific receptors on the neutrophil and prime it to excessive production of reactive oxygen intermediates (ROI) when triggered by contaminating bacterial products (Staphylococcus or lipopolysaccharide) or inflammatory cytokines like tumor necrosis factor. As a result of excessive production of ROI, the neutrophils are likely to be impaired in their capacity to kill bacteria. In support of this idea is the fact that may adsorbed proteins can not only bind and prime neutrophils, but they can also specifically bind (opsonize) bacteria and bacterial products. Such proteins include the plasma protein (fibrinogen), the extracellular matrix proteins (fibronectin, laminin), the platelet derived protein (thrombospondin), and lipopolysaccharide binding protein (LBP). The prosthetic surface would then become a platform for infection because it adsorbs proteins which both bind the bacteria and the neutrophil into a configuration which leads to massive and prolonged production of ROI which in turn downregulates oxidative killing. Furthermore, such a complex biomaterial/protein/bacterial surface is likely to stimulate macrophages: 1) to secrete cytokines which will downregulate phagocytic killing; and 2) to secrete nitric oxide which has the capacity to react with and quench the ROI needed to kill bacteria. The present proposal is designed to systematically elucidate the interactions between a few selected biomaterials and suspect opsonic proteins in order to determine how such proteins bind to biomaterial and how the complexes fix bacteria to the polymeric surface. Once it becomes clear that certain opsonic proteins can be adsorbed onto biomaterials and bind bacteria there, the effects of the biomaterial/protein/bacterial complex on neutrophil and macrophage responses can be determined. The ultimate goal is a more complete understanding of the net effect of these interactions on oxidative killing of bacteria in the presence of a prosthetic implant.