Trajectory 2 showed significant IL‐33 alarmin upregulation in COPD (log2FC 0.331, FDR adjusted p = 5.6e‐10) and elevation of multiple fibrotic signatures in pulmonary fibrosis, including TGFβ (log2FC 0.295, FDR adjusted p = 1.4e‐07), IL‐33 (log2FC 0.195, FDR adjusted p = 1.9e‐04), and IL‐4 + IL‐13 (log2FC 0.266, FDR adjusted p = 2.9e‐03) (Figure S13A). Here, IL33 is linked to pulmonary fibrosis.