Transcriptomic changes in GOLD grade 2 to 3 COPD with chronic bronchitis following metered cryospray

Introduction: Metered cryospray (MCS) significantly improves quality of life in COPD patients with chronic bronchitis (CB), using liquid nitrogen administered to the large airways, ablating abnormal epithelial tissue, and stimulating the regeneration of healthy cells. Hypothesis:GOLD grade 2 to 3 COPD with CB is associated with transcriptomic changes in large airway epithelial cells, that are altered by MCS, leading to the regeneration and treatment of dysplastic epithelial tissues Methods: Bronchial brushes were collected from patients (n=32) at baseline, 6 weeks and 6 months post-MCS or sham-procedure. Bulk RNA sequencing of all samples was analysed using R and pathway analysis consisted of Gene Set Variation Analysis and Gene Set Enrichment Analysis. Results:1756 genes were differentially expressed exclusively in the MCS group. Analysis revealed expression changes in WNT5B, by a log2 fold change of 0.62 in the MCS group(padj<0.05), and CXCL10, by 2.57 in the sham group with no concomitant change in the MCS group(padj<0.05). ELN and VANGL2 were upregulated, by 1.4 and 1.33 respectively in the MCS arm(padj<0.05), suggesting improved lung architecture. Enrichment of the DNA methylation gene signature in the MCS group was significantly altered compared to sham. An epithelial to mesenchymal transition gene signature was identified as significant in the treatment arm only. Conclusions:MCS altered abnormal lung epithelium morphology pathways and DNA methylation pathways, in patients with COPD with CB, suggesting the increase in quality of life is associated with regeneration and treatment of dysplastic epithelial tissues.