New Therapeutic Approach for Ricin-Induced Lung Injury

描述（由申请人提供）：全世界生物恐怖主义的威胁日益增加，对开发可用作生物武器的毒素治疗剂的需求不断升级。蓖麻毒素是蓖麻子（Ricinus communis）的天然产物和B类毒素。这是一种核糖体失活蛋白，由于其热稳定性、全球可获得性、易于生产并可作为气雾剂散发，有可能被用作生物武器，这是恐怖分子可能使用的一种途径。当作为可吸入气雾剂吸入时，其在呼吸道中引起不可逆的病理变化，导致上皮坏死、肺水肿和肺泡溢流，并最终死亡。蓖麻毒素（RT）是一种凝集素，由二硫键连接的两条多肽链组成，毒性需要进入细胞。B链（RTB）促进毒素进入细胞，A链（RTA）具有RNA N-糖苷酶活性，其通过使28 S真核核糖体RNA（rRNA）中的单个腺嘌呤脱嘌呤而使翻译失效，从而诱导核糖毒性。体外选择已用于产生对催化RTA特异性的RNA配体（适体）。这些RNA适体抑制RTA脱嘌呤并保护免受蓖麻毒素核糖毒性。我们假设，暴露后治疗可以开发针对蓖麻毒素核糖毒性通过提供这些新的抗RTA适体细胞内抑制RTA的活性和毒性。为了验证我们的假设，提出了以下目的：（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的功效和对蓖麻毒素细胞毒性的保护作用：（2）确定PEI适体对蓖麻毒素诱导的肺损伤和致死性的保护功效，并表征PEI适体在肺中的摄取;以及（3）验证PEI-适体在雾化蓖麻毒素小鼠模型中的功效。与公共卫生的相关性：由于目前还没有蓖麻毒素毒性的治疗方法，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，我们的长期目标是产生人类使用的抗毒素方案，以保护平民和军事人口免受蓖麻毒素在恐怖主义行为或战争中的使用。

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.