The Mechanism Of HDAC1-mediated Abnormal Deposition Of Extracellular Matrix In Pulmonary Artery

Background: pulmonary arterial hypertension（PAH）is a clinical syndrome with increased pulmonary vascular resistance and abnormal pulmonary pressure caused by a variety of factors,which can lead to right ventricular insufficiency,failure and even premature death.The pathogenesis of PAH mainly involves the imbalance of pulmonary vascular relaxation and contraction,pulmonary vascular remodeling and pulmonary vascular thrombosis in situ,among which pulmonary vascular remodeling is the most important.The pathological changes of PAH include pulmonary intima hyperplasia and thickening,media thickening,adventitia thickening and fibrosis and abnormal deposition of extracellular matrix,which eventually lead to pulmonary vascular remodeling,wall thickening and lumen stenosis.Abnormal deposition of extracellular matrix plays an important role in pulmonary vascular remodeling.The etiology of PAH is complex,in which epigenetic changes play an important role.Histone acetylation modification is one of the most widely and deeply studied epigenetic modifications.Histone acetylation is mainly regulated by histone deacetylases（HDACs）and histone acetyltransferase s（HATs）,which plays a key role in gene regulation.It has been found that HDAC1 plays a certain role in the abnormal deposition of extracellular matrix in most tissues The expression of HDAC1 is up-regulated in patients with pulmonary arterial hypertension and animal models of pulmonary arterial hypertension,which plays an important role in the occurrence and development of PAH,also,targeted inhibition of HDAC1 has a certain therapeutic potential for PAH,but the specific mechanism is not clear.The existing treatment of pulmonary arterial hypertension can’t significantly improve the prognosis of patients.Therefore,it is necessary to further explore the molecular mechanism of pulmonary vascular remodeling in PAH and explore new molecular targets for the treatment of PAH in order to improve the quality of life and survival rate of patients with PAH.Objective: To study and explore the role and possible molecular mechanism of HDAC1-mediated abnormal deposition of extracellular matrix in pulmonary artery in rats.Methods: Thirty-two healthy SPF male rats weighing 150-200 g were randomly divided into three groups: control group（CON group）,monocrotaline（MCT）model group（MCT group）and class I HDAC inhibitor（Entinostat,MS-275）intervention group（MCT+MS-275 group）.The rats in the CON group were not treated,the rats in the MCT group were injected intraperitoneally with monocrotaline（60mg/kg）on the first day of the experiment,and the rats in the MCT+MS-275 group were intraperitoneally injected with MCT（60mg/kg）on the first day of the experiment,followed by intraperitoneal injection of MS-275（3mg/kg）every other day.The experimental period was 28 days,during which the general condition of rats was observed and the death was recorded.28 days later,the survival rats were anesthetized.The right ventricular systolic blood pressure（RVSP）and right ventricular hypertrophy index（RVHI）were measured.The pulmonary vascular remodeling was evaluated by HE staining.The pulmonary vascular collagen deposition was observed by Masson trichromatic staining.The expression of HDAC1 in lung tissue sections was analyzed by immunofluorescence staining,and the expression of collagen I was detected by ELISA method.The protein levels of HDAC1 and tissue inhibitor of metalloproteinase-1（TIMP-1）were detected by Western blot method,the activity of matrix metalloproteinase2/9（MMP2/9）was determined by gel zymography.Results: 1.Compared with CON group,RVSP and RVHI of rats were significantly increased in MCT group（P<0.05）,percentage of medial wall thickness to outer diameter（MT%）of small pulmonary arteries was increased（P<0.05）,vascular lumen was narrowed significantly,and pulmonary vascular collagen deposition was increased,the expression of HDAC1,collagen I and TIMP-1 were up-regulated significantly（P<0.05）,the activity of MMP2/9 were increased（P<0.05）;2.Compared with MCT group,RVSP and RVHI of rats were significantly decreased in MCT+MS-275 group（P<0.05）,percentage of medial wall thickness to outer diameter（MT%）of small pulmonary arteries was decreased（P<0.05）,the degree of lumen stenosis is reduced,and pulmonary vascular collagen deposition was decreased,the expression of HDAC1,collagen I and TIMP-1 were down-regulated（P<0.05）,the activity of MMP2/9 were decreased（P<0.05）.Conclusion: The expression of HDAC1 was increased in MCT-induced pulmonary arterial hypertension in rats.HDAC1 mediates the abnormal deposition of extracellular matrix in rat pulmonary artery and contributes to the development of MCT-induced PAH in rats by by increasing the activity of MMP2/9,up-regulating the expression of TIMP-1 and subsequently increasing the expression of collagen I.Inhibition of HDAC1 can reduce the activity of MMP2/9,down-regulate the expression of TIMP-1,and subsequently down-regulate the expression of collagen I,then reduce the abnormal deposition of extracellular matrix in pulmonary artery and improve the occurrence and development of PAH,suggesting that inhibition of HDAC1 may be a new therapeutic strategy for the prevention and treatment of PAH.