To evaluate cytokine accumulation in the progression of COPD, the authors analyzed the serum concentrations of cytokines, such as TGF-β and IL-10, which are considered to be primarily anti-inflammatory, as well as pro-inflammatory cytokines, including TNF-α, IL-17 and IL-9 (Figure 1A). This evidence concerns the gene TGFB1 and chronic obstructive pulmonary disease.