ABSTRACT
Objectives: To explore the effect of 17β-estradiol (E2) on hypoxic pulmonary hypertension (HPH) and explore if the effects were mediated through suppressing pulmonary artery smooth muscle cells (PASMCs) proliferation by targeting miRNA-21 (miR-21). Methods: Animal experiment: A total of 32 healthy female SD rats with castrated surgery were randomly divided into 4 groups: normoxia group, normoxia+E2 group, hypoxia group, hypoxia+E2 group (n=8 each). The rats in normoxia+E2 group and hypoxia+E2 group received subcutaneous injection of E2 20 μg/kg/d, and the rest groups received subcutaneous injection of equal volume saline. The hypoxic groups were placed in the hypoxic chamber (24 hours per day for 8 weeks) to establish HPH model and normoxic groups were kept in the room air. The pulmonary artery remodeling, mean pulmonary artery pressure (mPAP), right ventricle hypertrophy index (RVHI) were observed. Real-time PCR and Western blot were used to detect the levels of proliferation cell nuclear antibody (PCNA) and miR-21 expression in pulmonary artery. In vitro: human pulmonary artery smooth muscle cells (hPASMCs) were randomly divided into 3 groups: normoxia group, hypoxia group, hypoxia+E2 group. The levels of cell proliferation in each group were tested by MTT after 24 hours. Real-time PCR and Western blot were used to detect the levels of PCNA and miR-21 in cells. Results: Animal experiment: compared with normoxia group, the hypoxia group showed obviously thickened pulmonary artery wall, increased mPAP and RVHI, and significantly increased expression of miR-21 and PCNA (P<0.01);above changed were significantly attenuated in hypoxia+E2 group (P<0.01). In vitro: compared with normoxia group, the hypoxia group showed obvious proliferation and significantly increased expression of miR-21 and PCNA (P<0.01);compared with hypoxia group, the proliferation of hPASMCs and expression of miR-21 and PCNA were obviously reduced in hypoxia+E2 group (P<0.01). Conclusions: E2 could effectively reduce mPAP, attenuate the degree of right heart hypertrophy and pulmonary vascular remodeling, the protective effect may be mediated through downregulating miR-21 and PCNA expression, and subsequently inhibiting the proliferation of hPASMCs.