Regarding the severity of airway obstruction as well as symptoms burden and the history of exacerbations (assessed by CAT), the gene expression of HSP70 and TLR2 was up-regulated in GOLD 2, GOLD 3 and GOLD 4 stages as well as in GOLD A, GOLD B and GOLD D groups, respectively, in comparison to the control group (Table 4). This evidence concerns the gene TLR2 and Airway obstruction.