Furthermore, BS exposure activates pulmonary macrophages and other cells, inducing IL-6, IL-8, MCP-1, MIP-2, and TNF-α production, which contributes to proteolysis and tissue remodelling27; still, in sputum, it has been described in lesser activation.28 These findings underscore the inflammatory heterogeneity present in COPD-BS, like that observed in COPD-TS. Here, CXCL8 is linked to chronic obstructive pulmonary disease.