TIMP3 and pulmonary fibrosis: To be specific, miR-34b-5p restricted extracellular matrix (ECM) degradation and enlarged the alveolar spaces continually via inhibiting the expression of tissue inhibitor of metalloproteinases-3 (TIMP3), which has been acknowledged as a pivotal regulator in lung homeostasis, to inhibit the progression of pulmonary fibrosis [65, 66].