TNF-α levels were decreased after TGF-β stimulation in lung fibroblasts from healthy subjects at normoxic conditions (p = 0.034) and a tendency at hypoxic conditions (p = 0.076), whereas there were no effects of either hypoxia or TGF-β stimuli in lung fibroblasts from COPD patients (Fig. 4e). Here, TNF is linked to chronic obstructive pulmonary disease.