To elucidate the important cellular and molecular drivers of pulmonary long COVID, we generated a single-cell transcriptomic map of the airway mucosa using bronchial brushings from patients with long COVID who reported persistent pulmonary symptoms.

Adults with and without long COVID were recruited from the general community in Greater Vancouver, Canada. The cohort was divided into those with pulmonary long COVID, which was defined as persons with new or worsening respiratory symptoms following ≥12 weeks from their initial acute severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (n=9); and control subjects defined as SARS-CoV-2 infected persons whose acute respiratory symptoms had fully resolved or individuals who had no history of acute coronavirus disease 2019 (COVID-19) (n=9). These participants underwent bronchoscopy from which a single cell suspension was created from bronchial brush samples and then sequenced.

A total of 56 906 cells were recovered for the downstream analysis, with 34 840 cells belonging to the pulmonary long COVID group, which strikingly showed a unique cluster of neutrophils in the pulmonary long COVID group (p<0.05). Ingenuity Pathway Analysis revealed that the neutrophil degranulation pathway was enriched across epithelial cell clusters. Differential gene expression analysis between the pulmonary long COVID and control groups demonstrated upregulation of inflammatory chemokines and epithelial barrier dysfunction across epithelial cell clusters, as well as over-expression of mucin genes across secretory cell clusters.

A single-cell transcriptomic landscape of the small airways suggest that neutrophils may play a significant role in mediating the chronic small airway inflammation driving pulmonary symptoms of long COVID.

为了阐明肺长期 COVID 的重要细胞和分子驱动因素，我们使用报告持续性肺部症状的长期 COVID 患者的支气管刷牙生成了气道粘膜的单细胞转录组图。

患有和没有长期 COVID 的成年人是从加拿大大温哥华的普通社区招募的。该队列分为肺长 COVID 患者，其定义为初次急性严重急性呼吸系统综合症冠状病毒 2 （SARS-CoV-2） 感染 ≥12 周后出现新发或恶化呼吸道症状的人 （n=9）;和对照受试者定义为急性呼吸道症状已完全消退的 SARS-CoV-2 感染者或没有 2019 年急性冠状病毒病 （COVID-19） 病史的个体 （n=9）。这些参与者接受了支气管镜检查，从支气管刷样本中制备单细胞悬液，然后进行测序。

共回收 56 906 个细胞用于下游分析，其中 34 840 个细胞属于肺长 COVID 组，在肺长 COVID 组中显着显示独特的中性粒细胞簇 （p<0.05）。Ingenuity Pathway 分析显示，中性粒细胞脱颗粒途径在上皮细胞簇中富集。肺长 COVID 组和对照组之间的差异基因表达分析表明，上皮细胞簇中炎症趋化因子和上皮屏障功能障碍上调，以及分泌细胞簇中粘蛋白基因的过度表达。

小气道的单细胞转录组学景观表明，中性粒细胞可能在介导导致长期 COVID 肺部症状的慢性小气道炎症中发挥重要作用。