Cathepsin B was also upregulated in COPD vs HV-ES in bronchial biopsies (log2FC of 0.246 p = 0.028) (Additional file 1: Figure S2B), but not in HV-ES vs HV-NS, log2FC of − 0.12 (p = 0.33) (Additional file 1: Figure S2D). This evidence concerns the gene CTSB and chronic obstructive pulmonary disease.