| Background:Pulmonary hypertension（PH）is a fatal disease characterized by pulmonary vascular remodeling.Its pathogenesis has not yet been elucidated.Vascular remodeling is the main pathophysiological bases of pulmonary hypertension and its complications,as well as the main reason for poor treatment of PH.Under normal conditions,autophagy can function as the protective mechanism against various diseases,but the imbalance of autophagy will aggravate the development of diseases under certain conditions.Autophagy is a dynamic process both in vivo and in vitro and the role of it in diseased status is much more complicated.Objective:To observe the expression of ATG-7（Autophagy-related gene 7）in the lung tissues of PH patients and PH mice,and to detect the pathophysiological phenomena of the lung caused by the deletion of ATG-7 in mouse PASMCs（Pulmonary artery smooth muscle cells）.As well as to explore the participation of ATG-7 regulate the mechanism of pulmonary hypertension.Methods:This study was divided into four parts:（1）Collecting pulmonary artery tissues from PH patients;（2）Establishing chronic hypoxia-induced PH mouse models;（3）Establishing gene knockout mouse（KO mouse）model;（4）Experiments in vitro to explore the molecular mechanism of ATG-7 involved in PH.The experiments were carried out according to the four parts above:（1）H&E Staining,Masson and elastic fiber morphological staining methods were used to observe the pathological changes of pulmonary artery wall in PH patients;（2）The hemodynamic detection method was used to determine the right ventricular pressure（RVP）and right ventricular mass index（RVMI）of hypoxia-induced PH mice;（3）The increased expression of ATG-7 in the lung tissues of PH patients and PH mice was determined by immunohistochemistry,western blotting and real-time PCR;（4）The use of echocardiography,hemodynamic testing,immunofluorescence and H&E staining were used to verify the successful construction of the KO mouse model;（5）Interference and over-expression techniques were used to detect the function of ATG-7 on PASMCs and explore the possible mechanism.Results:（1）H&E,Masson and elastic fiber morphological staining results showed that,compared with the control group,the collagen-meshwork of pulmonary vascular wall of PH patients were deformed,disorderly distributed,but increased in content;elastic fibers were broken;cell nuclei numbers were increased;（2）The hemodynamic results showed that the RVP and RVMI of PH mice were significantly higher than those of the control.Morphological staining also showed that the media of the pulmonary artery was thickened,the lumen became smaller and the content of collagen fibers in pulmonary vascular wall was increased,indicating that the PH model was successfully prepared;（3）The expression of ATG-7 was increased in the lung tissues of PH patients and PH mice;（4）SMC-ATG-7-/-mice model was proved to be successful based on tissue immunofluorescence and western blotting.Hemodynamic test results directly indicated that the RVP of SMC-ATG-7-/-mice was increased,and ultrasound results indirectly indicated that the pulmonary pressure index was increased,and the heart structure and function of SMC-ATG-7-/-mice were also changed;（5）Interfering with the expression of ATG-7 on mouse PASMCs can affect the proliferation,migration and phenotype of PASMCs.On the contrary,the transfection plasmid to overexpress ATG-7 can relatively inhibit cell proliferation.ATG-7 silencing participates in regulating vascular remodeling through PP2A/4EBP-1/elf-4E pathway.Conclusion:The expression of ATG-7 in the lung tissues of PH patients and PH mice was up-regulated,and the lack of ATG-7 in mice induced PH.Our study revealed that silencing ATG-7 promoted pulmonary vascular remodeling,involving cell proliferation,through the mechanism of PP2A/4EBP-1/elf-4E,which provides a new target for the treatment of PH. |
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