Mechanisms of anthrax lethal toxin-induced mortality and the novel biological-based targeted therapies

炭疽芽孢杆菌是炭疽病的病原体，自 2001年，炭疽病袭击。炭疽杆菌通过细菌感染和毒血症的组合导致炭疽病。作为一名 炭疽致死毒素(LT)是该病的主要毒力因子，在疾病的多个阶段起着至关重要的作用。 由于炭疽病病程较快，特别是早期出现非特异性、吸入性流行性感冒症状 炭疽病，患者通常在疾病已处于中晚期时寻求医疗帮助，使 炭疽病患者的临床管理是一项极具挑战性的任务。目前的治疗方法包括抗生素。 和抗毒素抗体，分别消除病原体和中和毒素。然而，没有 可用于处理已经到达其分子的LT引起的细胞/组织损伤的治疗方法 牢房内的目标。当宿主不能修复这种损伤时，死亡通常会随之而来，即所谓的“临界点” Return“是目前的治疗方法。因此，即使在重症监护下，系统性炭疽病的死亡率也很高， 达到50%。因此，迫切需要开发更好的靶向疗法，以避免 炭疽热导致的死亡。我们在这项应用中的目标是发现LT- 诱导致命性，并开发潜在的靶向疗法，以治疗超出“不返回点”的患者。 在这里，我们开始确定在炭疽病中干扰ERK、p38和JNK通路的具体作用- 诱导致死，发现潜在的分子机制，并发展重新激活的概念 /动员这些途径作为针对炭疽病所致死亡的靶向治疗。在目标1中，我们将确定 特异性干扰ERK通路在炭疽热致死中的作用。在三个核心MAPK中 作为LT靶向的通路，ERK通路是许多生物过程的基础，包括细胞 扩散和生存。因此，我们推测，破坏ERK途径是炭疽病的主要原因- 诱致性致死。我们将创造和使用包含MEK等位基因的新型小鼠模型，这些等位基因对LT- 裂解以了解ERK途径失活在炭疽病发病中的确切作用。在目标2中，我们将 进一步确定p38和JNK这两条主要的应激激活通路的破坏作用 在炭疽病的发病机制中，宿主为了适应无数的不利条件而激活。基于 我们强有力的初步数据表明，LT干扰的MAPK通路，特别是ERK通路，可以是 通过添加有效的有丝分裂原重新激活，在目标3中，我们将探索ERK通路的重新激活作为一种 炭疽热所致组织损伤的靶向治疗。 这些研究完成后，我们期望在以下方面取得重大的概念上的进展 我们对炭疽病发病的潜在分子机制的理解，并提供了证据- 开发炭疽靶向疗法的基础框架，这将补充目前的疗法 抗生素和抗毒素抗体，以防止炭疽死亡，即使在炭疽感染的晚期也是如此。

Bacillus anthracis, the causative agent of anthrax disease, has remained as a top bioterrorism concern since the 2001 anthrax attack. B. anthracis causes anthrax through a combination of bacterial infection and toxemia. As a major virulence factor, the anthrax lethal toxin (LT) plays an essential role during multiple steps of the disease. Due to the rapid course of anthrax disease, in particular, the early non-specific, flu-like symptoms of inhalational anthrax, patients usually seek medical assistance when the disease is already in the middle/late stages, making the clinical management of anthrax patients an extremely challenging task. Current treatments include antibiotics and anti-toxin antibodies that respectively eliminate the pathogen and neutralize the toxin. However, there is no therapy available to deal with the cellular/tissue damage caused by LT already having reached its molecular targets inside cells. Mortality usually follows when the host fails to repair this damage, the so called “point-of-no- return” for current therapy. Thus, even with intensive medical care, the mortality rate of systemic anthrax is high, reaching > 50%. Therefore, there is an urgent unmet clinical need to develop better targeted therapies to avert anthrax-induced mortality. Our goal in this application is to discover the molecular mechanisms underlying LT- induced lethality and to develop potential targeted therapeutics to treat patients beyond the “point-of-no-return”. Here, we set out to determine the specific roles of disrupting each of the ERK, p38, and JNK pathways in anthrax- induced lethality, discover the underlying molecular mechanisms, and develop the concept of reactivation /mobilization of these pathways as a targeted therapy for anthrax-induced mortality. In Aim 1, we will determine the role of specifically disrupting the ERK pathway in anthrax-induced lethality. Among the three core MAPK pathways targeted by LT, the ERK pathway is fundamental to many biological processes, including cell proliferation and survival. Thus, we hypothesize that disrupting the ERK pathway is the major cause of anthrax- induced lethality. We will generate and use novel mouse models containing MEK alleles that are resistant to LT- cleavage to understand the precise role of ERK pathway inactivation in anthrax pathogenesis. In Aim 2, we will further determine the roles of disrupting the p38 and JNK pathways, the two major stress-activated pathways that hosts activate in order to adapt to a myriad of unfavorable conditions, in anthrax pathogenesis. Based on our strong preliminary data that the LT-disrupted MAPK pathways, in particular the ERK pathway, can be reactivated by the addition of potent mitogens, in Aim 3, we will explore the ERK pathway reactivation as a targeted therapy for anthrax-induced tissue damage. Upon completion of these studies, it is our expectation that we will provide significant conceptual advances in our understanding of the underlying molecular mechanisms of anthrax pathogenesis, and offer an evidence- based framework for developing anthrax-targeted therapies, which will complement the current therapies with antibiotics and anti-toxin antibodies, to prevent anthrax mortality, even at advanced stages of anthrax infection.