An increase in STAT5 gene expression was observed in the COPD III and IV group compared to the other groups (Figure 7A, p = 0.0007), and unlike the lung tissue homogenate samples, there was a decrease in Foxp3 gene expression in the COPD I and II group compared to the NOS group (Figure 7B, p = 0.02). This evidence concerns the gene FOXP3 and chronic obstructive pulmonary disease.