Effects of microRNA-21 on endothelial-to-mesenchymal transition and its role in the pathogenesis of chronic obstructive pulmonary disease.

OBJECTIVES: Chronic obstructive pulmonary disease (COPD) is a disease characterized by persistent airflow restriction. This study aims to explore whether there is endothelial-to-mesenchymal transition (EndMT) in COPD mice and to explore the relationship between microRNA-21 (miR-21) and EndMT. METHODS: We established the COPD and the miR-21 gene knockout COPD animal model (both cigarette smoke-induced). Mice were divided into 3 groups (n=4): a control group, a COPD group, and a miR-21 knockout COPD (miR-21(-)/(-)-COPD) group. Masson trichrome staining was used to observe the deposition of collagen around the perivascular. The relative protein levels and positions of endothelial cell markers including vascular endothelial-cadherin (VE-cadherin), endothelial nitric oxide synthase (eNOS), and platelet endothelial cell adhesion molecule-1 (CD31) as well as mesenchymal cell markers including α-smooth muscle actin (α-SMA) and neural cadherin (N-cadherin) in lung tissues were observed by immunohistochemical staining. RESULTS: Compared with the control group, the area of collagen fibril deposition was increased in the COPD group (P<0.05), the expression levels of VE-cadherin, eNOS, and CD31 were all decreased (all P<0.05), and the expression levels of α-SMA and N-cadherin were increased (both P<0.05). Compared with the COPD group, the miR-21(-)/(-)-COPD group had a reduced area of collagen fiber deposition (P<0.05), the expression levels of VE-cadherin, eNOS, and CD31 were all increased (all P<0.05), and the expression levels of α-SMA and N-cadherin were decreased (both P<0.05). CONCLUSIONS: There is a EndMT process in cigarette smoke-induced COPD animal models.MiR-21 gene knockdown could reduce collagen deposition area and inhibit the EndMT process in COPD mice.