TGFB1 and chronic obstructive pulmonary disease: This was significantly greater than the NLFS and COPD groups which showed almost complete suppression of TGF-β1 in mild-moderate COPD and NLFS compared to NC (NLFS: 1% positive staining, COPD-CS: 0.6% and COPD-ES: 0.6%) (Figures 1, 2, Table 2).