Hyung‐Ju Cho

Background Allergic inflammation affects the epithelial cell populations resulting in goblet cell hyperplasia and decreased ciliated cells. Recent advances in single‐cell RNA sequencing (scRNAseq) have enabled the identification of new cell subtypes and genomic features of single cells. In this study, we aimed to investigate the effect of allergic inflammation in nasal epithelial cell transcriptomes at the single‐cell level. Methods We performed scRNAseq in cultured primary human nasal epithelial (HNE) cells and in vivo nasal epithelium. The transcriptomic features and epithelial cell subtypes were determined under IL‐4 stimulation, and cell‐specific marker genes and proteins were identified. Results We confirmed that cultured HNE cells were similar to in vivo epithelial cells through scRNAseq. Cell‐specific marker genes were utilized to cluster the cell subtypes, and FOXJ1 + ‐ciliated cells were sub‐classified into multiciliated and deuterosomal cells. PLK4 and CDC20B were specific for deuterosomal cells, and SNTN, CPASL, and GSTA2 were specific for multiciliated cells. IL‐4 altered the proportions of cell subtypes, resulting in a decrease in multiciliated cells and loss of deuterosomal cells. The trajectory analysis revealed deuterosomal cells as precursor cells of multiciliated cells and deuterosomal cells function as a bridge between club and multiciliated cells. A decrease in deuterosomal cell marker genes was observed in nasal tissue samples with type 2 inflammation. Conclusion The effects of IL‐4 appear to be mediated through the loss of the deuterosomal population, resulting in the reduction in multiciliated cells. This study also newly suggests cell‐specific markers that might be pivotal for investigating respiratory inflammatory diseases.

Objectives This study is aimed to investigate the differences in the clinical features and surgical outcomes between hypopnea‐ and apnea‐predominant obstructive sleep apnea (OSA). Design Cohort study. Setting Single tertiary care centre. Participants This study included 190 patients with OSA who underwent multilevel upper airway surgery between September 2012 and September 2021. The patients were divided into two groups according to the proportion of each respiratory event: hypopnea‐predominant ( n = 102) and apnea‐predominant ( n = 88). Main Outcome Measures The primary outcome measure was the percentage improvement in the apnea‐hypopnea index (AHI) from baseline AHI after surgery. Results The apnea‐predominant group included more male patients and had higher AHI, respiratory disturbance index (RDI) and oxygen desaturation index (ODI) than the hypopnea‐predominant group. Both groups showed significant improvements in AHI, apnea index, RDI, supine AHI, REM AHI, non‐REM AHI, ODI, lowest O 2 saturation and Epworth Sleepiness Scale scores following the surgery. Notably, hypopnea index increased after surgery in the apnea‐predominant OSA group. Although the improvement in the absolute value of AHI by surgery was significantly greater in the apnea‐predominant group than in the hypopnea‐predominant group, the two groups showed no significant difference in the percentage improvement in AHI from baseline AHI. Conclusion Patients with apnea‐predominant OSA had more severe disease than those with hypopnea‐predominant OSA; however, surgical outcomes, as evaluated by percentage AHI improvement, were comparable between the two groups. In addition, multilevel upper airway surgery may induce the transition from apnea to hypopnea in patients with apnea‐predominant OSA.