The Role And Mechanism Of Coupling Factor 6 In The Formation Of Hypoxia-induced Pulmonary Hypertension

BackgroundPulmonary hypertension is a high fatality disease,which lacks effective treatment and has poor clinical prognosis.The hemodynamic characteristics were mean pulmonary artery pressure(mPAP)>25 mmHg at rest,pulmonary capillary wedge pressure(PCWP)or left ventricular end-diastolic pressure<15 mmHg.According to the characteristics of PH hemodynamics,pathology and pathophysiology,PH can be divided into arteriopulmonary hypertension,pulmonary hypertension caused by left heart disease,pulmonary hypertension caused by pulmonary diseases and/or hypoxia,chronic thromboembolic pulmonary hypertension and other pulmonary artery obstructive diseases,and unknown and/or multiple causes.Hypoxic pulmonary hypertension(HPH)is a common type in these typies.The main pathological basis of PAH is the abnormal proliferation and migration of pulmonary artery smooth muscle cells,resulting in pulmonary artery stenosis and remodeling,leading to pulmonary hypertension.Therefore,the abnormal proliferation and migration of pulmonary artery-smooth muscle cells(PASMCs)is the key to the occurrence and development of HPH.There have been many studies on the abnormal proliferation and migration of PASMCs,and many factors have been found to be involved.For example,alpha enolase regulates the proliferation of PASMCs throughAMPK/AKT pathway,and NMDA glutamate receptor activation promotes the proliferation of PASMCs.However,the specific mechanism needs to be further clarified.Coupling factor 6(CF6)is a recently discovered cytokine involved in energy metabolism.CF6 is a structural subunit of ATP synthase.The precursor of human CF6 is composed of 128 amino acids.It is widely expressed in various tissues and organs and widely distributed in mitochondrial membrane.But it not only exists in mitochondria,but also densely distributes in cell membrane.CF6 is a strong vasoconstrictive peptide,which reduces the release of arachidonic acid(AA)by inhibiting the activity of phospholipase A2(PLA2),thus inhibiting the synthesis of PGI2,leading to vasoconstriction and elevated blood pressure.It is the only endogenous inhibitor of PGI2.At present,a large number of studies have found that the expression of CF6 is increased in hypertension,coronary heart disease and other cardiovascular diseases.Previously,CF6 was significantly increased in pulmonary tissues and plasma of rats with pulmonary hypertension induced by monocrotaline(MCT),suggesting that CF6 may be involved in the occurrence and development of MCT-induced PAH.However,its role and mechanism in HPH remain unclear.ObjectiveThe aim of this study is to explore the role and mechanism of CF6 in the occurrence and development of HPH by constructing a rat model of hypoxia-induced PAH and in vitro cell experiments,and to provide a new target for HPH treatment.MethodAnimal experiment:Rats were divided into experimental group and control group.Rats in experimental group were fed in hypoxic chamber for 28 days,and PAH rat model induced by hypoxiawas established.Rats in control group were fed in normal oxygen environment.On the 28th day of the experiment,the mean pulmonary artery pressure(mPAP)was measured,and the Fulton index(RV/LV+S)was calculated The right ventricular wall thickness and left and right ventricular area were examined by color Doppler echocardiography to confirm the success of hypoxic pulmonary hypertension in rats.After confirming the success of the model,the concentration of CF6 in plasma and the expression of CF6 in lung tissue were detected by ELISA,Western-blot and immunohistochemistry.Cell experiment:Rat pulmonary artery primary smooth muscle cells(PASMCs)were purchased and stimulated by CF6 for 24 hours.Cell proliferation and cell migration were detected by quantitative(CCK8)and qualitative(scratch)experiments.Result1.After 28 days of hypoxia,the blood pressure of rats in the experimental group was slightly higher than that in the control group,but the difference was not statistically significant(P<0.05).2.After 28 days of hypoxia,the mPAP,Fulton index,right ventricular wall thickness and right ventricular area in the experimental group were significantly higher than those in the control group(P<0.05),indicating that the HPH rat model was successful.3.The concentration of plasma CF6 in the experimental group increased in a time-dependent manner,peaked at the third week and decreased slightly at the fourth week,but it was still significantly higher than that in the control group(P<0.05).4.CCK8 results indicated that when CF6 concentration was 10-7 mmol/L,the absorbance of rat PASMCs cells stimulated by CF6 for 24 hours was significantly higher than that of the control group,and the difference was statistically significant(P<0.05).5.In the cell scratch test,PASMCs began to migrate to the midline 12 hours after CF6 stimulation.With the prolongation of stimulation time,the migration distance increased gradually,and the migration rate also increased significantly.Compared with the control group,the difference was statistically significant(P<0.05).ConclusionThe expression of CF6 in hypoxia-induced HPH rat model increased significantly,suggesting that CF6 plays an important role in the occurrence and development of HPH.Its possible mechanism is that CF6 promotes the proliferation and migration of PASMCs,leading to pulmonary artery remodeling,lumen stenosis and even occlusion.