SMAD3 and chronic obstructive pulmonary disease: It was shown that the expression of miR‐145‐5p significantly diminished in response to a CS condensate and negatively regulated proinflammatory cytokine release from airway smooth‐muscle cells in COPD by targeting SMAD3.24, 25 In the present study, we found that CSE treatment down‐regulated miR‐145‐5p in HBE cells and lung fibroblasts, and this effect was reversed by TUG1 knockdown.