The asthmatic epithelium/moDCs co-cultures (6.4 fold change (3.4 to 11.5 fold change)) as well as triple-co-cultures (3.5 fold change (1.8 to 5.7 fold change)) were characterised by the most substantial changes in IL-8 mRNA expression after UPM exposure compared to COPD (− 1.3 fold change (− 1.8 to 1.7 fold change), p = 0.01; (− 1.5 fold change (− 2.4 to 1.7 fold change), p = 0.04, for epithelial/moDCs and triple co-cultures, respectively) (Fig. 4). This evidence concerns the gene CXCL8 and chronic obstructive pulmonary disease.