Potent and Safe Inhibitors of B. anthracis Lethal Factor

描述(申请人提供)：炭疽致命因子的有效和安全的抑制物：炭疽主要是一种由革兰氏阳性、需氧、芽胞形成的炭疽杆菌引起的食草动物疾病。人类是意外宿主，几乎每个国家都报告了炭疽病例。自然产生或通过故意工程产生的抗药性细菌菌株的存在进一步强调了替代治疗方法的必要性。疫苗对于大型平民群体的预防性治疗通常是有问题的，因为必须以某种方式权衡不可避免的副作用和流行的可能性。炭疽病的发展依赖于一种分泌的毒素--致死因子(Lf)，这是一种通过裂解特定的人类细胞信号蛋白而在诱导巨噬细胞凋亡过程中发挥关键作用的蛋白酶。因此，通过靶向LF治疗感染的抗毒素方法应该是抗生素和疫苗的一种有希望的替代或补充。然而，由于缺乏有效和选择性的药理工具，进一步研究LF在炭疽疗法开发中的作用受到阻碍。基于这些观察，我们的研究提案中的一个中心假设是，能够阻断或降低LF活性的小有机分子将使炭疽杆菌无毒，使炭疽病与传统抗生素相结合可以治疗。我们建议基于多学科方法开发一系列新的LF抑制剂，包括基于片段的先导设计、药物化学和基于迭代结构的优化。将对最有希望的药物进行体外和最终的体内疗效研究。我们的三个具体目标是：(I)完成基于结构的有效抑制剂的设计，该抑制剂能够选择性地阻断LF切割活性，而不影响人的基质金属蛋白酶。(2)通过衍生和迭代，提高所选缓蚀剂支架的选择性、效力和安全性。(ILL)测试微调化合物在保护培养细胞方面的有效性，并确定LF的类药物铅抑制剂，用于继续药物精制和体内疗效研究。 相关性：吸入炭疽杆菌孢子会导致吸入性炭疽病，这是该病最致命的形式。随着疾病的发展，被肺泡巨噬细胞吞噬的孢子发芽产生细菌，细菌通过淋巴结传播到血液，最终导致全身性致命休克。为了成功地完成入侵，炭疽杆菌必须削弱宿主免疫系统。Lf(致死因子)是一种分泌型毒素，通过裂解特定的人类细胞信号蛋白，在诱导巨噬细胞凋亡(细胞死亡)中发挥关键作用。相反，特异性抑制Lf可防止巨噬细胞死亡，促进疾病的终止。我们将开发的LF抑制剂，最有可能与抗生素结合使用，应该会促进和确保携带这种疾病的患者的康复。

DESCRIPTION (provided by applicant): Potent and safe inhibitors of anthrax lethal factor: Anthrax is primarily a disease of herbivores caused by gram-positive, aerobic, spore-forming B. anthracis. Humans are accidental hosts and cases of anthrax have been reported from almost every country. The existence of antibiotic resistant bacterial strains that arise either naturally or through deliberate engineering further emphasizes the need for alternative therapeutic approaches. Vaccines are typically problematic for prophylactic treatment of large civilian groups, because the inevitable side-effects must somehow be weighed against the chances of epidemics. The progression of anthrax depends on a secreted toxin, LF (lethal factor), a protease that plays a key role in inducing apoptosis of macrophages by cleaving the specific human cell signaling proteins. Anti-toxin approaches that treat infection therapeutically by targeting LF should therefore provide a promising alternative or complement to antibiotics and vaccines. However, further research on the role of LF for the development of Anthrax therapies is hampered by the lack of potent and selective pharmacological tools. Based on these observations, a central hypothesis in our research proposal is that small organic molecules capable of blocking or reducing the activity of LF would render B. anthracis avirulent, making Anthrax disease treatable in combination with conventional antibiotics. We propose here to develop a novel series of LF inhibitors based on a multidisciplinary approach that involves fragment-based lead design, medicinal chemistry and iterative structure-based optimizations. In vitro and finally in vivo efficacy studies will be conducted on the most promising agents. Our three specific aims are: (I) To accomplish structure-based design of potent inhibitors capable of selectively blocking the LF cleavage activity without affecting human MMP enzymes. (II) To increase, through derivatizations and iterations, the selectivity, potency and safety of the selected inhibitor scaffolds. (Ill) To test the effectiveness of fine-tuned compounds in protecting the cultured cells and to identify the drug-like lead inhibitors of LF for continued drug refinement, and in vivo efficacy studies. Relevance: Inhaling B. anthracis spores causes inhalation anthrax, the most deadly form of the disease. As the disease progresses, the spores, engulfed by alveolar macrophages, germinate to generate the bacteria, which spread through the lymph nodes to the bloodstream, eventually leading to systemic fatal shock. To successfully accomplish invasion, B. anthracis has to weaken the host immune system. LF (lethal factor) is a secreted toxin that plays a key role in inducing apoptosis (cell-death) of macrophages by cleaving the specific human cell signaling proteins. Conversely, specific inhibition of LF should prevent macrophage cell-death and promote termination of the disease. The inhibitors of LF we will develop, most likely when used in combination with antibiotics, should facilitate and assure the recovery of patients who harbor the disease.