Selenocyanate as a novel treatment of cystic fibrosis lung disease

项目总结 感染介导的炎症过程推动进行性肺部疾病的机制(S)仍然存在 难以捉摸。新的初步数据支持进化选择性代谢途径，这可能解释 肺可以抵御病原体的侵袭，而不会在这个过程中伤害自己。我们发现， 含有硫氧还蛋白还原酶(SEC-TrxR)的哺乳动物硒半胱氨酸(SEC-TrxR)是一种存在于肺部的酶，可以 将卤代过氧化物酶产生的次硫氰酸盐(HOSCN)解毒，并将其循环回到-SCN。我们假设 从原核细菌中分离到含半胱氨酸的硫氧还蛋白还原酶(Cys-TrxR)。 铜绿假单胞菌由于酶结构的差异，尤其是缺乏C-末端，不能解毒HOSCN 只有高等真核生物中才有的硒半胱氨酸残基。囊性纤维化(CF)是由于囊性 纤维组织跨膜电导调节因子(CFTR)基因编码根尖膜阴离子 转运蛋白，可运输多种阴离子物种，包括-SCN。Cf受试者患有慢性肺病 导致与这种遗传性疾病相关的发病率和死亡率的感染。Cftr蛋白 转运-SCN进入呼吸道表面液体，我们假设这是异常宿主的关键特征 与慢性阻塞性肺疾病相关的防御。-SCN可以直接与HOCl反应生成HOSCN，后者可以 由宿主代谢，而不是病原体。我们提供了支持哺乳动物能力的初步数据 Sec-TrxR对HOSCN的解毒作用及原核细胞Cys-TrxR对HOSCN的解毒作用我们已经出版了 CFTR在维持呼吸道液体-SCN水平中的重要性的体内外数据和初步研究 吸入SCN显著改善铜绿假单胞菌的发病率和减少肺部炎症的研究 小鼠肺部感染模型。新的数据表明，一种SCN类似物，硒氰酸酯(-SECN)更有效 比SCN更抗微生物，但具有-SCN的所有选择性解毒好处。工作假说是 在慢性肺病中，肺不能以最佳方式利用-SCN，导致卤代过氧化物酶产生更多的次氯酸盐(HOCl)，这 没有选择性地解毒，会产生更多的肺损伤和炎症。具体目标1将决定 含SEC的TrxR抵抗HOSCN/HOSeCN氧化失活的化学机制 含有半胱氨酸的TrxR被HOSCN/HOSeCN灭活。特定目标2将检查CFTR和SEC-TrxR -SCN/HOSCN介导的肺宿主抵抗细菌感染的重要性。具体目标3 利用野生型和CFTR作为治疗肺部炎症和感染的潜在疗法 KO和-ENaC TG小鼠模型。该方案的主要创新点是：1)我们的新发现选择性 哺乳动物Sec-TrxR对HOSCN/HOSeCN的解毒作用，使肺能抵抗病原体 2)HOSCN/HOSeCN靶向原核Cys-TrxR；3)-SCN/-SECN可能 改善中性粒细胞和巨噬细胞的宿主防御功能；4)改善肺部感染模型 雾化-SECN；5)将SECN疗法引入临床的原理研究证据。

PROJECT SUMMARY The mechanism(s) by which infection-mediated inflammatory processes drive progressive lung disease remains elusive. Novel preliminary data supports an evolutionary selective metabolism pathway that may explain how the lung defends against pathogen colonization without harming itself in the process. We have discovered that mammalian selenocysteine containing thioredoxin reductase (Sec-TrxR), an enzyme found in the lung, can detoxify the haloperoxidase produced hypothiocyanate (HOSCN) and recycle it back to -SCN. We hypothesize that cysteine-containing thioredoxin reductase (Cys-TrxR) from prokaryotic bacteria such as E. coli and P. aeruginosa cannot detoxify HOSCN due to differences in enzyme structure, especially the lack of a C-terminal selenocysteine residue found only in higher eukaryotes. Cystic fibrosis (CF) is due to mutations in the cystic fibrosis transmembrane conductance regulator (cftr) gene that encodes for an apical membrane anion transporter protein that transports a number of anion species including -SCN. CF subjects have chronic lung infections that contribute to morbidity and mortality associated with this genetic disease. The CFTR protein transports -SCN into the airway surface fluid and we hypothesize that this is a critical feature of the aberrant host defense associated with CF lung disease. -SCN can directly react with HOCl producing HOSCN which can be metabolized by the host but not the pathogen. We provide preliminary data supporting the ability of mammalian Sec-TrxR to detoxify HOSCN and the inability of prokaryotic Cys-TrxR to detoxify HOSCN. We have published in vitro and in vivo data on the importance of CFTR in maintaining airway fluid -SCN levels and preliminary studies that inhaled -SCN dramatically improves morbidity and decreases lung inflammation in a P. aeruginosa lung infection mouse models. Novel data is presented that a SCN analog, selenocyanate (–SeCN), is more potent antimicrobial than SCN, but shares all the selective detoxification benefits of -SCN. The working hypothesis is that in CF the lung cannot use -SCN optimally resulting in haloperoxidases make more hypochlorite (HOCl) which is not selectively detoxified and produces more lung damage and inflammation. Specific aim 1 will determine the chemical mechanism by which Sec-containing TrxR resists inactivation by HOSCN/HOSeCN oxidation and Cys-containing TrxR are inactivated by HOSCN/HOSeCN. Specific aim 2 will examine CFTR’s and Sec-TrxR’s role in the importance of –SCN/HOSCN -mediated lung host defense against bacterial infection. Specific aim 3 Examine -SeCN as a potential therapy for treatment of lung inflammation and infection using wild type and CFTR KO and -ENaC Tg mouse models. The major innovations in this proposal are: 1) our novel discovery of selective detoxification of HOSCN/HOSeCN by mammalian Sec-TrxR that allows the lung to defend against pathogens without harming self; 2) novel targeting of prokaryotic Cys-TrxR by HOSCN/HOSeCN; 3) –SCN/-SeCN may improve neutrophil and macrophage host defense functions; 4) improvement in lung infection models with nebulized -SeCN; and 5) proof of principle studies to bring -SeCN therapy into the clinic.