Airway Alkalinization and Repurposing Tromethamine as a Therapeutic Approach in Cystic Fibrosis

项目摘要 尽管开发了新的治疗方法，囊性纤维化（CF）仍然是一种缩短寿命的疾病。呼吸道感染- 炎症开始于婴儿期并导致呼吸衰竭。因此，早期干预的目的是 纠正最初的主机防御缺陷和预防/减少感染可以大大提高 CF肺病的病程。众所周知，编码CFTR的基因中的突变， 3 导管通道，导致CF。然而，CF肺病的起源仍然不太清楚。我们不- 报道了CFTR的丢失损害了两种重要的气道宿主防御机制。（a）空气活动减少- 方式表面液体（ASL）抗菌剂。B）更粘稠的粘液，也有异常的性质，损害 其与粘膜下腺管分离的能力，从而阻碍粘膜纤毛转运（MCT）。在这两种情况下， CFTR介导的HCO 3分泌的丧失和异常酸性pH是关键因素。我们的长期目标是 开发靶向由于CFTR功能丧失导致的原发性宿主防御缺陷的新疗法。整体 本提案的目的是确定气道碱化，与一个重新利用的药物，可以预防或减轻， 导致CF气道疾病的发展。我们的假设是氨丁三醇导致的气道碱化 (THAM是FDA批准的用于人类临床代谢性酸中毒的碱化剂）， CF中的宿主防御和预防/减轻CF气道疾病的发展。我们在人类身上发现的， 雾化THAM（一种基于三羟甲基氨基甲烷的非碳酸氢盐缓冲剂）的猪，导致ASL pH值持续升高， 与NaHCO 3的短得多的持续时间相比，该效果持续数小时。THAM增强ASL细菌 杀死并降低粘液粘度。我们测试以下具体目标：目标1。雾化的THAM 在猪和人类中产生ASL pH值的长期增加并增强抗菌活性？基于 根据我们已发表和未发表的数据，我们的工作假设是，雾化THAM将增加ASL pH值， 并恢复ASL的抗菌性能，在人类和猪CF。目标2.气道碱化是否会影响- 证明MCT？从我们早期的研究中，我们假设气道碱化THAM将逆转MCT脱- 在CF中的作用，从而增强CF中的MCT。目标3.气道碱化是否减轻或预防早期气道 CF猪的疾病？我们已发表的和初步的数据表明，CF猪已经有气道宿主防御 出生时就存在缺陷，并在3周龄内发展为呼吸道疾病。因此，我们假设，在CF 猪，长期恢复ASL pH与THAM将改善气道宿主防御和减少或防止早期 CF猪的呼吸道疾病。我们处于独特的地位，可以将我们最近在发病机制方面的发现 转化为治疗干预。这些结果来自人类和临床前动物研究， 即，将改变CF和可能的其他气道疾病。它们将产生重要的积极影响 加速THAM和其他新的治疗干预措施和终点的临床开发， CF是新生儿CF筛查普及时代的一个至关重要的时间点。

PROJECT SUMMARY Despite the development of new therapies, cystic fibrosis (CF) remains a life-shortening disease. Airway infec- tion and inflammation begin during infancy and lead to respiratory failure. Thus, early interventions aimed at correcting the initial host defense defects and preventing/reducing infection could dramatically improve the course of CF lung disease. It is well known that mutations in the gene encoding CFTR, a HCO – and Cl– con- 3 ducting channel, cause CF. Yet, the origins of CF lung disease have remained less well understood. We dis- covered that loss of CFTR impairs two important airway host defense mechanisms. a) Reduced activity of air- way surface liquid (ASL) antimicrobials. b) More viscous mucus that also has abnormal properties, impairing its ability to detach from submucosal gland ducts, thus hindering mucociliary transport (MCT). In both cases, loss of CFTR-mediated HCO3– secretion and an abnormally acidic pH are key factors. Our long-term goal is to develop novel therapeutics that target primary host defense defects due to loss of CFTR function. The overall objective of this proposal is to determine if airway alkalinization, with a repurposed drug, can prevent or allevi- ate the development of CF airway disease. Our hypothesis is that airway alkalinization with tromethamine (THAM, an FDA-approved alkalinizing agent in human clinical use for metabolic acidosis), will restore airway host defenses in CF and prevent/alleviate the development of CF airway disease. We found in humans and pigs that aerosolized THAM, a tris-based, non-bicarbonate buffer, causes a sustained increase in ASL pH and the effect lasts for hours, in contrast to a much shorter duration with NaHCO3. THAM enhanced ASL bacterial killing and decreased mucus viscosity. We test the following Specific Aims: Aim 1. Does aerosolized THAM produce a prolonged increase in ASL pH and enhance antimicrobial activity in pigs and humans? Based upon our published and unpublished data, our working hypothesis is that aerosolized THAM will increase ASL pH and restore ASL antimicrobial properties, in humans and pigs with CF. Aim 2. Will airway alkalinization im- prove MCT? From our earlier studies, we postulate that airway alkalinization with THAM will reverse MCT de- fects in CF, thereby enhancing MCT in CF. Aim 3. Does airway alkalinization alleviate or prevent early airway disease in CF pigs? Our published and preliminary data show that CF pigs already have airway host defense defects present at birth and develop airway disease within 3 weeks of age. Thus, we hypothesize that, in CF pigs, long-term restoration of ASL pH with THAM will improve airway host defense and lessen or prevent early airway disease in CF pigs. We are uniquely positioned to translate our recent discoveries on the pathogenesis of CF lung disease into a therapeutic intervention. These results, from both human and preclinical animal stud- ies, will be transformative for CF and likely other airway diseases. They will have an important positive impact on accelerating clinical development of THAM and other new therapeutic interventions and endpoints for early CF, a critically important time point in the era of universal newborn CF screening.