IL1B and chronic obstructive pulmonary disease: Functionally, M1 macrophage-induced iNOS, IL-1β, IL-6, IL-8, and TNF-α contribute to oxidative stress and airway inflammation, while M2 macrophage-induced TGF-β facilitates epithelial–mesenchymal transition (EMT)-based small airway remodelling in COPD (46, 47, 50).