Hemodynamic and anti-Toxin Treatments in Anthrax Lethal Toxin Challenged Canines

炭疽致命毒素挑战犬的血流动力学和抗毒素治疗

• 批准号: 8952905
• 负责人: Peter Eichacker
• 金额: --
• 依托单位: CLINICAL CENTER
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8952905
• 关键词: Address; Adenylate Cyclase; Algorithms; American; Animal Model; Anthrax disease; Antibodies; Antigens; Attention; Bacterial Toxins; Calmodulin; Canis familiaris; Cardiac; Cardiovascular system; Catecholamines; Catheters; Cessation of life; Chest; Critical Illness; Data; Disease Outbreaks; Edema; Effectiveness; Escherichia coli; Exotoxins; Image; Inflammatory; Infusion procedures; International; Lipopolysaccharides; Liquid substance; Lung; MAP2K1 gene; Manuscripts; Measures; Metalloproteases; Mitogen-Activated Protein Kinase Kinases; Modeling; Monitor; Monoclonal Antibodies; Myocardial dysfunction; Nitric Oxide; Norepinephrine; Organism; Pathogenesis; Patients; Perfusion; Publications; Publishing; Rattus; Regimen; Research; Resistance; Shock; Societies; Staphylococcus aureus; Testing; Toxin; United States; United States National Institutes of Health; Vasoconstrictor Agents; Work; Zinc; anthrax lethal factor; anthrax toxin; base; biodefense; cytokine; edema factor; hemodynamics; improved; in vivo; pressure; programs; protective effect; response; symposium; uptake

Although shock resistant to conventional hemodynamic support with fluids and vasopressors contributed to death in all five nonsurvivors in the 2001 United States anthrax outbreak, its mechanisms and optimal management remain unclear. Lethal (LeTx) and edema (ETx) toxin are major contributors to the pathogenesis of anthrax. Both LeTx and ETx consist of protective antigen (PA) which is necessary for cellular uptake of the toxic moities; lethal factor (LF) for LeTx and edema factor (EF) for ETx. Lethal factor is a zinc metalloproteinase that inhibits mitogen activated protein kinase kinases (MAPKK1-4, 6 and 7) while EF is a calmodulin dependent adenyl cyclase. Recent research has shown that LeTx and ETx produce cellular changes different from those associated with more commonly encountered bacterial toxins such as lipopolysaccharide (LPS) or the exotoxins of gram-positive organisms like S. aureus. Despite this research, there has been limited in vivo work defining these toxins cardiovascular effects. Furthermore, although there have been major efforts to develop and test new toxin directed agents, little attention has been paid to the efficacy of conventional fluid, vasopressor and inotrope support during anthrax toxin associated shock. Work done largely in our laboratiory suggests these responses may be difficult to predict. In a rat model, 24 h LeTx infusion produced lethality and shock, but it did not alter circulating inflammatory cytokines, nitric oxide or catecholamines. In this model, while PA directed monoclonal antibody (PA-mAb, 5H3 or Raxibacumab) (HGS, Rockville, MD) was protective, regimens of fluid or norepinephrine support beneficial with LPS or E. coli, were not with LeTx (4 - 6). In fact fluids not only worsened survival with LeTx but also negated the effects of PA-mAb. Although informative, the rat model did not permit the duration (i.e. > 24h) or type of hemodynamic monitoring (i.e. systemic and pulmonary arterial catheter measures and serial cardiac imaging) necessary to fully characterize the cardiovascular effects of LeTx and ETx. Therefore a canine model was developed with support from the Trans-NIH/FDA Biodefense Program. In initial studies, LeTx challenge in the canine produced many of the same changes noted in the rat. LeTx was also associated with myocardial depression in the canine. The purpose of present study is to use the now developed canine anthrax LeTx model to comprehensively investigate the effects of fluid and vasopressor treatment alone and in combination with a toxin directed treatment. An advantage of this model not possible in smaller animal models is the ability to titrate hemodynamic support based on measures of preload and perfusion pressure just as it is done in critically ill patients. Specifically, this study will address whether a standard regimen (fluid and norepinephrine infusion) or a toxin directed therapy (i.e. 5H3-mAb or Raxibacumab) are beneficial when used alone or together in canines challenged with 24 h infusions of LeTx. Based on earlier studies with this canine model, treatment algorithms have been developed for the sequential administration of fluid and norepinephrine titrated using preload measures. Studies examining the effects of hemodynamic support and Raxibacumab with LeTx challenge are complete. Addition of Raxibacumab to hemodynamic support improved hemodynamics, reduced vasopressor needs and fluid retention and increased survival following LeTx challenge. This data was presented at the International Conference of the American Thoracic Society 2011 and has now been published. (Barochia et al. Protective antigen antibody augments hemodynamic support in anthrax lethal toxin shock in canines. J Infect Dis. 2012; 205: 818 829.) Studies are now also complete examining the effects of Raxibacumab and hemodynamic support alone or together with ETx challenge alone and with ETx and LeTx in combination in this same canine model. Raxibacumab also augmented hemodynamic support and improved survival with ETx alone and with ETx and LeTx together. These findings were presented at the International Conference of the American Thoracic Society in 2013 and 2014. A manuscript has been submitted for consideration of publication.

虽然休克抵抗传统的血液动力学支持液体和血管加压药导致死亡的所有五个非幸存者在2001年美国炭疽爆发，其机制和最佳管理仍不清楚。致死毒素（LeTx）和水肿毒素（ETx）是炭疽病发病机制的主要贡献者。LeTx和ETx都由保护性抗原（PA）组成，其是细胞摄取毒性部分所必需的; LeTx的致死因子（LF）和ETx的水肿因子（EF）。致死因子是一种锌金属蛋白酶，可抑制丝裂原活化蛋白激酶激酶（MAPKK 1 -4、6和7），而EF是一种钙调蛋白依赖性腺苷酸环化酶。最近的研究表明，LeTx和ETx产生的细胞变化与更常见的细菌毒素（如脂多糖（LPS）或革兰氏阳性生物体（如S.金黄色。尽管有这项研究，但定义这些毒素心血管效应的体内工作有限。此外，尽管已经做出了重大努力来开发和测试新的毒素导向剂，但是很少关注常规液体、血管加压药和正性肌力药支持在炭疽毒素相关休克期间的功效。在我们的实验室中进行的大量工作表明，这些反应可能很难预测。 在大鼠模型中，24小时LeTx输注产生致死性和休克，但它没有改变循环炎性细胞因子，一氧化氮或儿茶酚胺。在该模型中，虽然PA定向的单克隆抗体（PA-mAb，5 H3或Raxibacumab）（HGS，Rockville，MD）是保护性的，但液体或去甲肾上腺素支持方案有益于LPS或E. coli，不含LeTx（4 - 6）。事实上，液体不仅使LeTx的存活率恶化，而且还否定了PA-mAb的作用。 尽管提供了信息，但大鼠模型不允许充分表征LeTx和ETx的心血管效应所需的血液动力学监测的持续时间（即> 24小时）或类型（即全身和肺动脉导管测量和连续心脏成像）。因此，在Trans-NIH/FDA生物防御计划的支持下开发了犬模型。在最初的研究中，犬的LeTx激发产生了许多与大鼠相同的变化。LeTx也与犬的心肌抑制有关。 本研究的目的是使用现在开发的犬炭疽LeTx模型，以全面调查流体和血管加压剂治疗单独和与毒素定向治疗相结合的效果。该模型在较小动物模型中不可能实现的一个优点是能够根据前负荷和灌注压的测量来滴定血流动力学支持，就像在重症患者中所做的那样。具体而言，本研究将探讨标准方案（液体和去甲肾上腺素输注）或毒素导向治疗（即5 H3-mAb或Raxibacumab）在LeTx输注24 h激发的犬中单独或联合使用时是否有益。基于该犬模型的早期研究，已经开发了使用前负荷测量进行液体和去甲肾上腺素滴定的顺序给药的治疗算法。 检查血流动力学支持和雷巴单抗与LeTx激发的影响的研究已经完成。在血液动力学支持中添加Raxibacumab可改善血液动力学，减少血管加压药需求和液体潴留，并增加LeTx激发后的存活率。该数据在2011年美国胸科学会国际会议上发表，现已发表。（Barochia等人，保护性抗原抗体增强犬科动物炭疽致死毒素休克中的血液动力学支持。2012; 205：818 829.） 研究现在也完成了检查Raxibacumab和血流动力学支持单独或与ETx单独激发以及ETx和LeTx组合在同一犬模型中的作用。Raxibacumab还增强了血流动力学支持，并改善了ETx单独使用以及ETx和LeTx联合使用的生存率。这些研究结果在2013年和2014年的美国胸科学会国际会议上发表。 已提交一份手稿供考虑出版。