Abstract
BackgroundPulmonary hypertension (PH) is a progressive and fatal disease. While cigarette smoke can change DNA methylation status, the role of such molecular alterations in smoke-associated PH is unclear.MethodsA PH rat model was developed by exposing animals to cigarette smoke for 3 months. Right ventricular systolic pressure was measured with a right heart catheter. Histological changes (right ventricular hypertrophy index, medial wall thickness in pulmonary arteries (PAs)) and DNMT1 protein levels in rat PAs or primary human PA smooth muscle cells (HPASMCs) exposed to cigarette smoke extract were assessed. Methylation sequencing and MassArray® were used to detect genomic and RASEF promoter methylation status, respectively. After DNMT1 knockdown and cigarette smoke extract exposure, HPASMCs behavior (proliferation, migration) and RASEF methylation status were examined; RASEF mRNA expression was evaluated by real-time-polymerase chain reaction. RASEF overexpression viral vectors were used to assess the impact of RASEF on rat PH and HPASMCs remodeling.ResultsHigher right ventricular systolic pressure, medial wall thickness, and right ventricular hypertrophy index values were observed in the smoking group rats. Smoke exposure increased DNMT1 expression and RASEF methylation levels in rat PAs and HPASMCs. Cigarette smoke extract induced HPASMCs behavioral changes and RASEF hypermethylation followed by silencing, while DNMT1 knockdown markedly inhibited these changes. RASEF overexpression distinctly inhibited PH and HPASMCs remodeling, possibly through phospho-AKT (Ser473), PCNA, and MMP9 downregulation.ConclusionsCigarette smoke caused PA remodeling in PH rats related to RASEF hypermethylation. These results expand our understanding of key epigenetic mechanisms in cigarette smoke-associated PH and potentially provide a novel therapeutic target for PH.
Highlights
Pulmonary hypertension (PH) is defined as an increase in mean pulmonary arterial pressure above 25 mmHg at rest
DNA methyltransferase 1 (DNMT1) overexpression has been found in PH tissues and involved in hypoxia-induced human Pulmonary arteries (PAs) smooth muscle cells (HPASMCs) proliferation and apoptotic resistance [21]. 5-Azacytidine (5-Aza), a selective DNMT1 inhibitor, has been shown to inhibit platelet-derived growth factor-induced aortic and airway smooth muscle cells (SMCs) proliferation and migration, and has a protective role in atherosclerosis and asthma [22, 23]
Cigarette smoke induced PH in rats The Right ventricle systolic pressure (RVSP) was significantly higher in the smoking group (37.2 ± 3.5 mmHg) than in the air group (22.2 ± 1.0 mmHg, P < 0.01, Fig. 1a, b)
Summary
Pulmonary hypertension (PH) is defined as an increase in mean pulmonary arterial pressure above 25 mmHg at rest. Pulmonary arterial smooth muscle remodeling (PASMR) can lead to media thickening, a main pathological characteristic of PH [5, 6], due to increased proliferation, apoptotic resistance, and migration of PA smooth muscle cells (SMCs) [7]. Cigarette and tobacco smoke have been shown to strongly modify genome methylation [14, 15], which is related to many diseases, such as COPD [16], lung cancer [17], and atherosclerosis [18]. 5-Azacytidine (5-Aza), a selective DNMT1 inhibitor, has been shown to inhibit platelet-derived growth factor-induced aortic and airway SMC proliferation and migration, and has a protective role in atherosclerosis and asthma [22, 23]. While cigarette smoke can change DNA methylation status, the role of such molecular alterations in smoke-associated PH is unclear
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