Division of Molecular and Clinical Medicine, University of Dundee, Ninewells Hospital and Medical School, Dundee, UK.
Respiratory Department, Hospital Clinic, University of Barcelona, IDIBAPS, CIBERES, Barcelona, Spain.
Lancet Respir Med. 2021 Aug;9(8):873-884. doi: 10.1016/S2213-2600(20)30504-X. Epub 2021 Feb 17.
Bronchiectasis is predominantly a neutrophilic inflammatory disease. There are no established therapies that directly target neutrophilic inflammation because little is understood of the underlying mechanisms leading to severe disease. Neutrophil extracellular trap (NET) formation is a method of host defence that has been implicated in multiple inflammatory diseases. We aimed to investigate the role of NETs in disease severity and treatment response in bronchiectasis.
In this observational study, we did a series of UK and international studies to investigate the role of NETs in disease severity and treatment response in bronchiectasis. First, we used liquid chromatography-tandem mass spectrometry to identify proteomic biomarkers associated with disease severity, defined using the bronchiectasis severity index, in patients with bronchiectasis (n=40) in Dundee, UK. Second, we validated these biomarkers in two cohorts of patients with bronchiectasis, the first comprising 175 patients from the TAYBRIDGE study in the UK and the second comprising 275 patients from the BRIDGE cohort study from centres in Italy, Spain, and UK, using an immunoassay to measure NETs. Third, we investigated whether pathogenic bacteria had a role in NET concentrations in patients with severe bronchiectasis. In a separate study, we enrolled patients with acute exacerbations of bronchiectasis (n=20) in Dundee, treated with intravenous antibiotics for 14 days and proteomics were used to identify proteins associated with treatment response. Findings from this cohort were validated in an independent cohort of patients who were admitted to the same hospital (n=20). Fourth, to assess the potential use of macrolides to reduce NETs in patients with bronchiectasis, we examined two studies of long-term macrolide treatment, one in patients with bronchiectasis (n=52 from the UK) in which patients were given 250 mg of azithromycin three times a week for a year, and a post-hoc analysis of the Australian AMAZES trial in patients with asthma (n=47) who were given 500 mg of azithromycin 3 times per week for a year.
Sputum proteomics identified that NET-associated proteins were the most abundant and were the proteins most strongly associated with disease severity. This finding was validated in two observational cohorts, in which sputum NETs were associated with bronchiectasis severity index, quality of life, future risk of hospital admission, and mortality. In a subgroup of 20 patients with acute exacerbations, clinical response to intravenous antibiotic treatment was associated with successfully reducing NETs in sputum. Patients with Pseudomonas aeruginosa infection had a lessened proteomic and clinical response to intravenous antibiotic treatment compared with those without Pseudomonas infections, but responded to macrolide therapy. Treatment with low dose azithromycin was associated with a significant reduction in NETs in sputum over 12 months in both bronchiectasis and asthma.
We identified NETs as a key marker of disease severity and treatment response in bronchiectasis. These data support the concept of targeting neutrophilic inflammation with existing and novel therapies.
Scottish Government, British Lung Foundation, and European Multicentre Bronchiectasis Audit and Research Collaboration (EMBARC).
支气管扩张症主要是一种中性粒细胞炎症性疾病。目前尚无针对中性粒细胞炎症的既定治疗方法，因为人们对导致严重疾病的潜在机制知之甚少。中性粒细胞胞外诱捕网（NET）的形成是一种宿主防御方法，它与多种炎症性疾病有关。我们旨在研究 NET 在支气管扩张症疾病严重程度和治疗反应中的作用。
在这项观察性研究中，我们进行了一系列英国和国际研究，以调查 NET 在支气管扩张症疾病严重程度和治疗反应中的作用。首先，我们使用液相色谱-串联质谱法鉴定了与支气管扩张症严重程度指数定义相关的疾病严重程度的蛋白质组学生物标志物，该指数用于评估英国邓迪的 40 名支气管扩张症患者。其次，我们使用免疫测定法在英国 TAYBRIDGE 研究的 175 名患者和意大利、西班牙和英国 BRIDGE 队列研究的 275 名患者的两个支气管扩张症队列中验证了这些生物标志物。第三，我们研究了是否致病性细菌在严重支气管扩张症患者的 NET 浓度中起作用。在一项单独的研究中，我们招募了邓迪的支气管扩张症急性加重患者（n=20），他们接受了 14 天的静脉抗生素治疗，并使用蛋白质组学来识别与治疗反应相关的蛋白质。该队列的研究结果在同一医院收治的 20 名患者的独立队列中得到了验证。第四，为了评估大环内酯类药物在支气管扩张症患者中降低 NET 的潜在用途，我们检查了两项大环内酯类药物长期治疗研究，一项是在英国的 52 名支气管扩张症患者中进行的，他们每周服用 250 毫克阿奇霉素三次，为期一年，以及澳大利亚 AMAZES 试验中接受每周三次 500 毫克阿奇霉素治疗一年的哮喘患者的事后分析。
痰液蛋白质组学鉴定出 NET 相关蛋白是最丰富的，也是与疾病严重程度最密切相关的蛋白。这一发现在两个观察队列中得到了验证，其中痰液 NET 与支气管扩张症严重指数、生活质量、未来住院风险和死亡率相关。在 20 名急性加重的患者亚组中，静脉抗生素治疗的临床反应与成功降低痰液中的 NET 有关。与无铜绿假单胞菌感染的患者相比，铜绿假单胞菌感染患者对静脉抗生素治疗的蛋白质组学和临床反应较差，但对大环内酯类药物治疗有反应。在支气管扩张症和哮喘患者中，低剂量阿奇霉素治疗 12 个月可显著降低痰液中的 NET。
我们将 NET 确定为支气管扩张症疾病严重程度和治疗反应的关键标志物。这些数据支持使用现有和新型疗法靶向中性粒细胞炎症的概念。
苏格兰政府、英国肺脏基金会和欧洲多中心支气管扩张症审计和研究合作组织（EMBARC）。
