Southampton NIHR Respiratory Biomedical Research Unit, Southampton University Hospital, Southampton, UK.
Clinical and Experimental Sciences, University of Southampton Faculty of Medicine, Sir Henry Wellcome Laboratories, Southampton University Hospital, Southampton, UK.
Lancet. 2015 Feb 26;385 Suppl 1:S42. doi: 10.1016/S0140-6736(15)60357-9.
Incomplete understanding of mechanisms and clinicopathobiological heterogeneity in asthma hinders research progress. Pathogenic roles for T-helper-type 17 (Th17) cells and invariant T cells implied by murine data have yet to be assessed in man. We aimed to investigate the role of Th17 and mucosal associated invariant T (MAIT) cells in airway inflammation; to characterise associations between diverse clinical and immunological features of asthma; and to identify novel multidimensional asthma endotypes.
In this single-centre, cross-sectional observational study in the UK, we assessed volunteers with mild-to-severe asthma and healthy non-atopic controls using clinical and physiological assessment and immunological sampling of blood, induced sputum, endobronchial biopsy, and bronchoalveolar lavage for flow cytometry and multiplex-electrochemiluminescence assays. Primary outcomes were changes in frequencies of Th17 and MAIT cells between health and asthma using Mann-Whitney U tests and the Jonckheere-Terpstra test (linear trend across ranked groups). The study had 80% power to detect 60% differences in T-cell frequencies at p<0·05. Bayesian Network Analysis (BNA) was used to explore associations between parameters. Topological Data Analysis (TDA) was used to identify multidimensional endotypes. The study had local research ethics approval. All participants provided informed consent.
Participants were 84 male and female volunteers (60 with mild-to-severe asthma and 24 healthy, non-atopic controls) aged 18-70 years recruited from clinics and research cohorts. Th17 cells and γδ17 cells were not associated with asthma, even in severe neutrophilic forms. MAIT-cell frequencies were strikingly reduced in asthma compared with health (median frequency in blood 0·9% of CD3+ cells [IQR 0·3-1·8] in asthma vs 1·6 [1·2-2·6] in health, p=0·005; in sputum 1·1 [0·7-2·0] vs 1·8 [1·6-2·3], p=0·002; and in biopsy samples 1·3 [0·7-2·3] vs 3·9% [1·3-5·3%], p=0·02), especially in severe asthma where BAL regulatory T cells were also reduced compared with those in health (4·4, 3·1-6·1, vs 8·1, 5·6-10; p=0·02). BNA and TDA identified six novel clinicopathobiological clusters of underlying disease mechanisms, with elevated mast cell mediators tryptase (p<0·0001), chymase (p=0·02), and carboxypeptidase A3 (p=0·02) in severe asthma.
This study suggests that Th17 cells do not have a major pathogenic role in human asthma. We describe a novel deficiency of MAIT cells in severe asthma. We also provide proof of concept for application of TDA to identification of multidimensional clinicopathobiological endotypes. Endotypes will require validation in further cohorts.
Wellcome Trust.
对哮喘发病机制和临床病理生物学异质性的不完全了解阻碍了研究进展。鼠类研究中暗示的辅助性 T 细胞 17（Th17）细胞和固有 T 细胞的致病作用尚未在人类中进行评估。我们旨在研究 Th17 和黏膜相关不变 T（MAIT）细胞在气道炎症中的作用；描述哮喘不同临床和免疫学特征之间的关联；并确定新的多维哮喘表型。
在英国的这项单中心、横断面观察性研究中，我们使用临床和生理评估以及血液、诱导痰、支气管活检和支气管肺泡灌洗的免疫取样，评估了轻度至重度哮喘和健康非过敏性对照志愿者。使用曼-惠特尼 U 检验和琼克赫斯特-特普斯特拉检验（等级组中线性趋势）评估健康与哮喘之间 Th17 和 MAIT 细胞频率的变化。该研究有 80%的功效来检测 p<0.05 时 60%的 T 细胞频率差异。贝叶斯网络分析（BNA）用于探索参数之间的关联。拓扑数据分析（TDA）用于识别多维表型。该研究获得了当地研究伦理委员会的批准。所有参与者均提供了知情同意。
参与者为 84 名男性和女性志愿者（60 名患有轻度至重度哮喘，24 名健康、非过敏性对照），年龄 18-70 岁，来自诊所和研究队列。Th17 细胞和 γδ17 细胞与哮喘无关，即使是严重的中性粒细胞性形式。与健康相比，哮喘患者 MAIT 细胞频率明显降低（血液中 MAIT 细胞频率中位数为 0.9%的 CD3+细胞[IQR 0.3-1.8]，哮喘患者为 1.6 [1.2-2.6]，p=0.005；在痰中为 1.1 [0.7-2.0]，p=0.002；在活检样本中为 1.3 [0.7-2.3]，p=0.02），尤其是在严重哮喘中，与健康相比，BAL 调节性 T 细胞也减少（4.4、3.1-6.1，vs 8.1、5.6-10；p=0.02）。BNA 和 TDA 确定了六个潜在疾病机制的新型临床病理生物学簇，严重哮喘中肥大细胞介质类胰蛋白酶（p<0.0001）、糜蛋白酶（p=0.02）和羧肽酶 A3（p=0.02）升高。
本研究表明 Th17 细胞在人类哮喘中没有主要的致病作用。我们描述了严重哮喘中 MAIT 细胞的新缺陷。我们还提供了证据表明 TDA 可用于鉴定多维临床病理生物学表型。表型将需要在进一步的队列中进行验证。
惠康信托基金会。
