Another study demonstrated that some inflammatory genes (IL-1β, IL-6, IL-8, CCL2 and CCL8) were upregulated, whereas some growth factor receptor genes (BMPR2, CTGF, FGF1, KDR and TEK) were downregulated in lung tissue samples from patients who were current smokers or had moderate COPD [33]. Here, CCL8 is linked to chronic obstructive pulmonary disease.