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Pulmonary hypertension (PH) mainly results from excessive proliferation of pulmonary artery smooth muscle cells (PASMCs) and displays mitochondrial abnormalities such as mitochondrial fragmentation. Epigallocatechin-3-gallate (EGCG), an efficient antiproliferative compound in green tea, has recently been demonstrated to inhibit PASMCs proliferation. However, the pre-clinical issues as to whether EGCG attenuates PH and the underlying mechanisms have yet to be addressed. The present study was undertaken to investigate the therapeutic effects of EGCG on PH and its effects on mitochondrial fragmentation in PASMCs. Rats exposed to hypoxia (10% O 2 , 3 weeks) developed PH. EGCG (50, 100 or 200 mg/kg/d, i.g.) dose-dependently attenuated right ventricular systolic pressure, pulmonary vascular remodeling and right ventricular hypertrophy, increased expression of mitochondrial fusion protein - mitofusin-2 (MFN-2), and promoted mitochondrial fusion as evidenced by decreased number and volume of mitochondria in PASMCs of pulmonary arteries. Notably, EGCG (50 μM) downregulated hypoxia-induced (3% O 2 , 48 h) PASMCs mitochondrial fragmentation and inhibited PASMCs proliferation via KLF-4/MFN-2/p-Erk signaling pathway. Collectively, our data demonstrated that EGCG exerts antiproliferative effects via regulating mitochondrial fragmentation of PASMCs and EGCG holds the promise as a drug against PH. [ABSTRACT FROM AUTHOR]

Pulmonary artery smooth muscle cells (PASMCs) phenotypic switching and pulmonary artery endothelial cells (PAECs) endothelial-mesenchymal transition (EndMT) are important in promoting pulmonary hypertension (PH)-pulmonary vascular remodeling (PVR). Resveratrol can efficiently inhibit the proliferation of PASMCs, but its application is limited due to its low bioavailability and solubility. In this study, we modified resveratrol to assess the role of A ring N(CH 3) 2 -based derivatives of resveratrol (Res4) in PVR-PASMCs phenotypic switching and PVR-PAECs EndMT. Chemical methods were used for the preparation of Res4; NMRS and HPLC were used to authenticate Res4. Mice developed PVR after 4 weeks of hypoxia (10% O 2). Res4 (50 mg/kg/d) attenuated right ventricular systolic pressure, right ventricular hypertrophy, and PVR. PASMCs developed phenotypic switching and PAECs developed EndMT after 2 days of hypoxia (3% O 2). Res4 (10 μM) could inhibit PASMCs and PAECs viability. Res4 could decrease proliferating cell nuclear antigen (PCNA) and osteopontin (OPN) expression, and increase α-smooth muscle actin (α-SMA) and vimentin expression in PASMCs. It could also decrease PCNA, α-SMA, vimentin expression and increase platelet endothelial cell adhesion molecule (CD31) expression in PAECs. Notably, Res4 inhibited the phosphorylation levels of mitogen-activated protein kinase kinase (MEK), extracellular signal-regulated protein kinase (ERK), Jun-N-terminal kinase (JNK), and p38 kinase in hypoxia-treated PASMCs and PAECs, indicating MAPK pathway may be involved in Res4-induced inhibition of PASMCs phenotypic switching and PAECs EndMT. Our data demonstrated that Res4 exerts antiproliferative effects by regulating PASMCs phenotypic switching and PAECs EndMT. Res4 may be potentially used as a drug against PH-PVR. [ABSTRACT FROM AUTHOR]