BACKGROUND Monocytes and macrophages are critical innate immune cells of the airways. Despite their differing functions, few clinical studies discriminate between them and little is known about their regulation in asthma. OBJECTIVE We aimed to distinguish and quantify macrophages, monocytes and monocyte subsets in induced sputum and blood, and examine their relationship with inflammatory and clinical features of asthma. Methods We applied flow cytometry to distinguish macrophages, monocytes and subsets in sputum and blood (n=53; 45 asthma, 8 non-asthma) and a second asthma sputum cohort (n=26). Monocyte subsets were identified by surface CD14/CD16 (CD14++ CD16- classical, CD14+ CD16+ intermediate and CD14+ CD16++ non-classical monocytes). Surface CD206, a marker of monocyte tissue differentiation, was measured in sputum. Relationship to airway inflammatory phenotype (neutrophilic n=9, eosinophilic n=14, paucigranulocytic n=22) and asthma severity (severe n=12, non-severe n=33) was assessed. RESULTS Flow cytometry- and microscope-quantified sputum differential cell proportions were significantly correlated. Sputum macrophage number was reduced (p=0.036), while classical monocyte proportion was increased in asthma vs non-asthma (p=0.032). Sputum classical monocyte number was significantly higher in neutrophilic vs paucigranulocytic asthma (p=0.013). CD206- monocyte proportion and number were increased in neutrophilic vs eosinophilic asthma (p<0.001, p=0.013). Increased sputum classical and CD206- monocyte numbers in neutrophilic asthma were confirmed in the second cohort. Blood monocytes did not vary with airway inflammatory phenotype, but blood classical monocyte proportion and number were increased in severe vs non-severe asthma (p=0.022, p=0.011). CONCLUSION & CLINICAL RELEVANCE Flow cytometry allowed distinction of sputum macrophages, monocytes and subsets, revealing compartment-specific dysregulation of monocytes in asthma. We observed an increase in classical and CD206- monocytes in sputum in neutrophilic asthma, suggesting co-recruitment of monocytes and neutrophils to the airways in asthma. Our data suggest further investigation of how airway monocyte dysregulation impacts on asthma-related disease activity is merited.

中文翻译：

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中性粒细胞哮喘的特点是气道经典单核细胞增加

背景技术单核细胞和巨噬细胞是气道的关键先天免疫细胞。尽管它们的功能不同，但很少有临床研究能区分它们，而且对它们在哮喘中的调节知之甚少。目的我们旨在区分和量化诱导痰和血液中的巨噬细胞、单核细胞和单核细胞亚群，并检查它们与哮喘炎症和临床特征的关系。方法 我们应用流式细胞术来区分痰液和血液中的巨噬细胞、单核细胞和亚群（n=53；45 例哮喘患者，8 例非哮喘患者）和第二个哮喘痰液队列（n=26）。通过表面 CD14/CD16（CD14++ CD16- 经典、CD14+ CD16+ 中间和 CD14+ CD16++ 非经典单核细胞）鉴定单核细胞亚群。在痰液中测量了表面 CD206，一种单核细胞组织分化的标志物。评估了与气道炎症表型（中性粒细胞 n=9，嗜酸性粒细胞 n=14，少粒细胞 n=22）和哮喘严重程度（严重 n=12，非严重 n=33）的关系。结果流式细胞仪和显微镜量化的痰细胞比例显着相关。痰中巨噬细胞数量减少（p=0.036），而哮喘与非哮喘患者的经典单核细胞比例增加（p=0.032）。中性粒细胞哮喘与少粒细胞哮喘患者的痰经典单核细胞数显着升高（p=0.013）。CD206-单核细胞比例和数量在嗜中性哮喘与嗜酸性哮喘中增加（p<0.001，p=0.013）。在第二个队列中证实了嗜中性哮喘患者痰中经典和 CD206 单核细胞数量增加。血单核细胞不随气道炎症表型而变化，但严重哮喘与非严重哮喘患者的血液经典单核细胞比例和数量增加（p=0.022，p=0.011）。结论和临床相关性 流式细胞术可以区分痰巨噬细胞、单核细胞和亚群，揭示哮喘中单核细胞的隔室特异性失调。我们观察到中性粒细胞哮喘患者痰液中的经典单核细胞和 CD206- 单核细胞增加，表明单核细胞和中性粒细胞共同募集到气道中。我们的数据表明，值得进一步研究气道单核细胞失调对哮喘相关疾病活动的影响。揭示哮喘中单核细胞的隔室特异性失调。我们观察到中性粒细胞哮喘患者痰液中的经典单核细胞和 CD206- 单核细胞增加，表明单核细胞和中性粒细胞共同募集到气道中。我们的数据表明，值得进一步研究气道单核细胞失调对哮喘相关疾病活动的影响。揭示哮喘中单核细胞的隔室特异性失调。我们观察到中性粒细胞哮喘患者痰液中的经典单核细胞和 CD206- 单核细胞增加，表明单核细胞和中性粒细胞共同募集到气道中。我们的数据表明，值得进一步研究气道单核细胞失调对哮喘相关疾病活动的影响。