BACTERIAL MEMBRANE PROTEINS IN GRAM-NEGATIVE SEPSIS

革兰氏阴性脓毒症继续导致大量的发病率和死亡率。许多病理生理学被认为是由毒性细菌细胞壁分子引起的，包括脂多糖（LPS），其引起直接毒性和/或诱导继发性促炎反应。我们的初步数据表明，LPS是从垂死的细菌中释放出来的，血液中含有三种保守的外膜蛋白（OMPs），这些OMPs本身可能具有生物活性。这三种细菌膜蛋白已被鉴定为外膜蛋白A（OmpA）、肽聚糖相关脂蛋白（PAL）和胞壁蛋白脂蛋白（MLP）。该提案的总体目标是评价OmpA、PAL和MLP在革兰氏阴性脓毒症中的作用，最终目标是开发一种使用交叉反应性抗OMP抗体治疗脓毒症的策略。我们的第一个具体目标是扩大研究，表明有一种形式的PAL从细菌表面释放，以低密度与人类脂蛋白一起漂浮。我们的第三个具体目标是研究针对OmpA，PAL和MLP上表位的单克隆和多克隆IgG结合和中和每个外膜蛋白的生物学效应并促进LPS/OMP复合物的视蛋白吞噬作用的能力。我们最后的具体目标是研究单克隆和多克隆免疫球蛋白G针对OmpA，PAL和MLP在两种革兰氏阴性菌感染模型中的保护效力。这些研究将促进我们对革兰氏阴性脓毒症病理生理学的基本理解。每种OMP在革兰氏阴性菌的临床菌株中是高度保守的。因此，该项目的成功结果将为开发用于治疗脓毒症的人用抗OMP抗体提供直接和立即的方法。

Gram-negative sepsis continues to cause substantial morbidity and mortality. Much of the pathophysiology is believed to be caused by toxic bacterial cell wall molecules, including lipopolysaccharides (LPS), that cause direct toxicity and/or induce a secondary pro-inflammatory response. Our preliminary data indicate that LPS is released from dying bacteria that blood in complexes that contain three conserved outer membrane proteins (OMPs), and that these OMPs may have biological activity themselves. The three bacterial membrane proteins have been identified as outer membrane protein A (OmpA), peptidoyglycan associated lipoprotein (PAL), and murein lipoprotein (MLP). The overall objective of the proposal is to evaluate the role(s) of OmpA, PAL, and MLP in Gram-negative sepsis, with the ultimate goal of developing a strategy of treating sepsis with cross-reacting anti-OMP antibodies. Our first specific aim is to expand studies suggesting that there is a form of PAL released from the bacterial surface that floats at low density together with human lipoproteins. Our third specific aim is to study monoclonal and polyclonal IgG directed to epitopes on OmpA, PAL, and MLP for their ability to bind and neutralize the biological effects of each outer membrane protein and to promote opsinophagocyosis of LPS/OMP complexes. Our final specific aim is to study the protective efficacy of monoclonal and polyclonal immunoglobulin G directed to OmpA, PAL, and MLP in two models of Gram-negative infection. The studies should advance our fundamental understanding of the pathophysiology of Gram-negative sepsis. Each of the OMPs are highly conserved amongst clinical strains of Gram-negative bacteria. Therefore, a successful outcome of the project would provide a direct and immediate approach to developing anti-OMP antibodies for human use for the treatment of sepsis.