New Therapeutic Approach for Ricin-Induced Lung Injury

描述（由申请人提供）：世界范围内日益增加的生物恐怖主义威胁已经升级了对可用于生物武器的毒素治疗方法的开发需求。蓖麻毒素是蓖麻（Ricinus communis）的天然产物，属于B类毒素。它是一种核糖体失活蛋白，由于其热稳定性、全球可用性、易于生产，并且可以作为气溶胶传播，恐怖分子可能会使用这种途径，因此有可能被用作生物武器。当作为可吸入的气溶胶吸入时，它会引起呼吸道不可逆的病理改变，导致上皮坏死、肺水肿和肺泡充血，最终导致死亡。蓖麻毒素（RT）是一种由二硫桥连接的两条多肽链组成的凝集素，需要进入细胞才能产生毒性。b链（RTB）促进毒素进入细胞，a链（RTA）具有RNA n -糖苷酶活性，通过去纯化28S真核核糖体RNA （rRNA）中的单个腺嘌呤来禁用翻译，从而诱导核毒性。体外选择已被用于产生RNA配体（适体）特异性的催化RTA。这些RNA适配体抑制RTA去嘌呤化，并对蓖麻毒素的核毒性有保护作用。我们假设暴露后处理可以通过在细胞内递送这些新的抗RTA适配体来抑制RTA活性和毒性。为了验证我们的假设，我们提出了以下目标：(1)在细胞培养模型中测试聚阳离子聚乙烯亚胺（PEI）促进适体的细胞摄取和对蓖麻毒素细胞毒性的保护作用；(2)确定pei -适配体对蓖麻毒素诱导的肺损伤和致死性的保护作用，并描述pei -适配体在肺中的摄取情况；(3)在雾化蓖麻毒素小鼠模型上验证pei适配体的有效性。与公共卫生的相关性：由于目前没有治疗蓖麻毒素毒性的方法，因此迫切需要开发有效的蓖麻毒素解毒剂。由于蓖麻毒素是一种重要的生物恐怖主义威胁，我们的长期目标是开发人类使用的抗毒素方案，以保护平民和军队人口免受恐怖主义或战争行为中使用蓖麻毒素的影响。

DESCRIPTION (provided by applicant): The increasing threat of bioterrorism worldwide has escalated the demand for the development of therapeutics for toxins that can be used as biological weapons. Ricin is a natural product of the castor bean (Ricinus communis) and a Category B toxin. It is a ribosome-inactivating protein that has the potential of being used as a biological weapon because of its heat stability, worldwide availability, ease in production and can be disseminated as an aerosol, a likely route that terrorists may use. When inhaled as a respirable aerosol, it causes irreversible pathological changes in the respiratory tract resulting in epithelial necrosis, pulmonary edema and alveolar flooding, and eventual death. The ricin toxin (RT) is a lectin consisting of two polypeptide chains linked by a disulfide bridge and cellular entry is required for toxicity. The B-chain (RTB) facilitates entry of the toxin into the cell and the A-chain (RTA) possesses RNA N-glycosidase activity that disables translation by depurinating a single adenine in the 28S eukaryotic ribosomal RNA (rRNA), thereby inducing ribotoxicity. In vitro selection has been used to generate RNA ligands (aptamers) specific for the catalytic RTA. These RNA aptamers inhibited RTA depurination and protects against ricin ribotoxicity. We hypothesize that post-exposure treatment can be developed against ricin ribotoxicity by delivering these novel anti-RTA aptamers intracellularly to inhibit RTA activity and toxicity. To test our hypothesis, the following aims are proposed: (1) To test the efficacy of the polycation polyethylenimine (PEI) in facilitating cellular uptake of aptamers and protective effects against ricin cytotoxicity in cell culture models; (2) To ascertain the efficacy of PEI-aptamers in the protection against ricin-induced lung injury and lethality and characterize the uptake of PEI-aptamers in the lungs; and (3) To validate the efficacy of PEI-aptamers in an aerosolized ricin mouse model. Relevance to Public Health: Since there is currently no treatment for ricin toxicity, there is an urgent need to develop effective antidotes for ricin. Because ricin is an important bioterrorist threat, our long-term goal is generate anti-toxin regimen for human use to protect the civilian and military populations against the use of ricin in acts of terrorism or war.