Pseudomonas aeruginosa Adaptation During Early CF Airway Infection and Treatment

描述（由申请人提供）： 肺部疾病是遗传性疾病囊性纤维化（CF）患者预期寿命和生活质量的主要决定因素。机会性革兰氏阴性菌铜绿假单胞菌感染大多数CF患者的呼吸道，感染这种病原体显然与更差的呼吸结局相关。铜绿假单胞菌在生命早期感染CF气道。多年来，细菌适应CF气道环境并刺激炎症反应，这些炎症反应在根除感染方面无效，但会损害气道。预防铜绿假单胞菌定植和消除慢性感染的策略的发展将需要了解细菌对CF肺病的自然史。该辅助拨款提案描述了一个包括CF临床医生，微生物学家和流行病学家的合作项目，该项目将利用两项大型，相互关联，正在进行的CF微生物学多中心研究产生的独特资源，称为囊性纤维化研究中的早期抗假单胞菌治疗（EPIC）。我们建议使用EPIC试验中的铜绿假单胞菌临床分离株、相关临床数据和独特的临床研究指导机会来研究铜绿假单胞菌对CF气道适应的自然史。具体而言，拟议的项目将定义感染铜绿假单胞菌的临床相关性，该铜绿假单胞菌携带新发现的适应性变化：编码主要转录调节因子LasR的基因中的失活突变。在最近的一项单中心横断面研究中，我们发现这种突变在CF慢性气道感染早期发生，平均比粘液性（最佳描述的铜绿假单胞菌CF适应性变化）早两年，但患病率相似。此外，LasR突变体感染与加速肺功能下降相关。可能与这一发现有关，初步证据表明LasR突变导致对CF治疗中最常用的三类抗生素的耐药性增加：内酰胺类，氨基糖苷类和氟喹诺酮类。相反，LasR突变体在体外对至少两类代谢抑制剂更敏感，这表明感染这些分离株的患者的替代治疗策略。因此，在慢性铜绿假单胞菌CF气道感染期间LasR突变的出现可以作为疾病进展的标志物，并且可以为携带这些适应性突变体的患者开发新的疗法。然而，为了解决这些方法的效用，我们的初步流行病学研究结果必须在一个更大的，多中心的人口验证。我们建议确定EPIC试验中招募的幼儿中LasR突变铜绿假单胞菌感染的患病率和相关临床特征，以检验LasR突变在铜绿假单胞菌CF感染期间相对常见和早期发生的假设，并与先前的抗生素暴露、肺功能加速下降和更频繁的呼吸道加重相关。这项研究的结果将澄清CF肺病的自然史，并可能导致目前CF治疗方案的改进。公共卫生相关性：囊性纤维化（CF）是高加索人最常见的遗传性疾病。CF患者死于慢性肺部感染的中位年龄为37岁，这限制了他们的生活质量和寿命。该项目将研究导致CF肺部感染的细菌之间的差异，以及这些细菌特征与肺部疾病进展之间的关系。该项目的目标是更好地了解CF肺病的发病机制，以便开发更好的治疗方法。

DESCRIPTION (provided by applicant): Lung disease is the primary determinant of life expectancy and quality of life among people with the genetic disease cystic fibrosis (CF). The opportunistic Gram-negative bacterium Pseudomonas aeruginosa infects the respiratory tracts of most patients with CF, and infection with this pathogen is clearly associated with worse respiratory outcomes. P. aeruginosa infects CF airways early in life. Over many years, bacteria adapt to the CF airway environment and stimulate inflammatory responses that are ineffective in eradicating the infection, yet damage airways. The development of strategies to prevent P. aeruginosa colonization and eliminate chronic infection will require an understanding of the natural history of the bacterial contribution to CF lung disease. This ancillary grant proposal describes a collaborative project including CF clinicians, microbiologists, and epidemiologists that will make use of the unique resources generated from two large, interrelated, ongoing multicenter studies of CF microbiology, known as the Early Antipseudomonal Therapy in Cystic Fibrosis studies (EPIC). We propose to use the P. aeruginosa clinical isolates, linked clinical data, and unique clinical research mentorship opportunities available from the EPIC trials to study the natural history of P. aeruginosa adaptation to the CF airway. Specifically, the proposed project will define the clinical relevance of infection with P. aeruginosa carrying a newly-identified adaptive change: inactivating mutation in the gene encoding the major transcriptional regulator LasR. In a recent single-center, cross-sectional study, we found this mutation to occur early during CF chronic airway infection, on average two years earlier than mucoidy (the best-described P. aeruginosa CF adaptive change), yet with a similar prevalence. Furthermore, LasR mutant infection was associated with accelerated lung function decline. Perhaps related to this finding, preliminary evidence suggests that LasR mutation leads to increased resistance to the three classes of antibiotic used most often in CF therapy: ¿lactams, aminoglycosides, and fluoroquinolones. Conversely, LasR mutants are more susceptible in vitro to at least two classes of metabolic inhibitors, suggesting alternative therapeutic strategies for patients infected with these isolates. Thus, the emergence of LasR mutation during chronic P. aeruginosa CF airway infections may serve as a marker for advancing disease, and novel therapies could be developed for patients carrying these adaptive mutants. However, to address the utility of these approaches, our preliminary epidemiologic findings must be validated in a larger, multicenter population. We propose to define the prevalence and associated clinical features of LasR mutant P. aeruginosa infection among the young children enrolled in the EPIC trials, to test the hypothesis that LasR mutation occurs relatively commonly and early during P. aeruginosa CF infections, and is associated with preceding antibiotic exposure, accelerated decline in lung function, and more frequent respiratory exacerbations. The results of this study will clarify the natural history of CF lung disease, and may lead to improvements in current CF therapeutic regimens. PUBLIC HEALTH RELEVANCE: Cystic fibrosis (CF) is the most common genetic disease of Caucasians. People with CF die at a median age of 37 years from chronic lung infections that limit their quality and length of life. This project will examine the differences among the bacteria that cause CF lung infections, and the relationship between these bacterial characteristics and lung disease progression. The goal of this project is to better understand the pathogenesis of CF lung disease so that better treatments can be developed.