CXCL10 Induces Proliferation Of Pulmonary Artery Smooth Muscle Cells To Promote Pulmonary Vascular Remodeling In Chronic Thromboembolic Pulmonary Hypertension

【Backgroud】Chronic thromboembolic pulmonary hypertension(CTEPH)is a pulmonary vascular disease with insidious onset,progressive exacerbation,and poor prognosis.The pulmonary artery lesions of CTEPH mainly include fibrous thrombosis in the proximal pulmonary artery and peripheral pulmonary vascular remodeling.From a pathophysiological perspective,the peripheral pulmonary vascular remodeling characteristics of CTEPH are similar to those of pulmonary arterial hypertension,including thickening of the pulmonary artery intima and media,intimal fibrosis,abnormal proliferation of pulmonary artery smooth muscle cells,and plexiform lesions.Clinical and animal experimental studies have shown that fibrous thrombi in the pulmonary artery of CTEPH can cause passive diversion of blood flow from the obstructed pulmonary artery area to the unobstructed pulmonary artery area,leading to an increase in blood flow and pulmonary artery pressure in the unobstructed pulmonary artery area.The abnormally increased pulmonary blood flow load may mediate the occurrence and development of peripheral pulmonary vascular remodeling of CTEPH through the inflammatory reaction around the pulmonary artery.CXCL10 is a chemokine that acts on the CXC chemokine receptor CXCR3.It is highly expressed in the lungs and peripheral blood,mainly secreted by white blood cells(monocytes,T lymphocytes,neutrophils,etc.),and has strong leukocyte chemotaxis.It is involved in the occurrence and development of various inflammatory diseases and tumors.Clinical research found that the level of systemic circulation CXCL10 in patients with CTEPH was significantly increased,and was related to the patient’s six-minute walking distance.In cell experiments,exogenous CXCL10 can induce the migration and proliferation of fibroblasts,which may be involved in the formation of fibrous thrombi in pulmonary arteries.In addition,exogenous CXCL10 stimulation of pulmonary artery endothelial cells can affect intracellular and extracellular calcium homeostasis,and induce abnormal proliferation and migration of pulmonary artery endothelial cells,which may be involved in the disease progression of pulmonary arterial hypertension.Although the current research has confirmed that the level of CXCL10 in systemic circulation in patients with CTEPH is increased,It is still unknown whether CXCL10 is related to pulmonary hemodynamics in patients with CTEPH or whether it improves with the progression of treatment for CTEPH patients.Moreover,there is currently no research to elucidate whether the CXCL10/CXCR3 axis plays a role in the progression of CTEPH.【Objects】The aim of this study was to test and compare the plasma CXCL10 levels in patients with CTEPH before and after balloon pulmonary angioplasty(BPA)and healthy controls,and to explore the correlation between the plasma CXCL10 levels in patients with CTEPH and pulmonary hemodynamics;Furthermore,this study aims to identify the source of abnormal increase in plasma CXCL10 levels in CTEPH patients by detecting the expression and localization of CXCL10 in pulmonary artery tissue;In order to explore the mechanism of CXCL10/CXCR3 axis in peripheral pulmonary vascular remodeling of CTEPH,this study aims to use a left pulmonary artery ligation rat model(LPAL)to simulate abnormal blood flow status of CTEPH,to detect the expression level of CXCL10/CXCR3 axis under high blood flow,and to investigate the impact of CXCL10/CXCR3 axis on peripheral pulmonary vascular remodeling;At the cellular level,this study aims to bidirectional regulate the CXCL10/CXCR3 axis of pulmonary artery smooth muscle cells through exogenous CXCL10 or CXCR3 antagonists AMG487,to detect the proliferation of pulmonary artery smooth muscle cells(PASMC),and to clarify the mechanism of abnormal blood flow load regulating peripheral pulmonary vascular remodeling of CTEPH through the CXCL10/CXCR3 axis.【Methods】(1)Plasma CXCL10 levels in CTEPH patients before and after BPA,as well as in healthy controls,were tested;(2)The correlation between plasma CXCL10 level and pulmonary hemodynamics in patients with CTEPH was analyzed;(3)LPAL rat model was constructed;(4)Cardiac and pulmonary pathological indicators such as right ventricular systolic pressure,right ventricular hypertrophy index,and right pulmonary vascular remodeling in LPAL rats were evaluated;(5)The expression of CXCL10 and CXCR3 in the right lung tissue of LPAL rats was tested;(6)The proliferation of right lung PASMC in LPAL rats was tested;(7)On the basis of the LPAL rat model,the CXCR3 antagonist AMG487 was administered;(8)Cardiac and pulmonary pathological indicators such as right ventricular systolic pressure,right ventricular hypertrophy index,and right pulmonary vascular remodeling in LPAL rats administered with AMG487 were evaluated;(9)The expression levels of CXCL10 and CXCR3 in the right lung tissue of LPAL rats treated with AMG487 was tested;(10)The proliferation of right lung PASMC in LPAL rats treated with AMG487 was evaluated;(11)Using normal and LPAL rats’ right pulmonary artery smooth muscle cells,exogenous CXCL10 or AMG487 stimulation was administered to evaluate cell proliferation,and to evaluate the effect of regulating the CXCL10/CXCR3 axis of pulmonary artery smooth muscle cells on proliferation.【Results】1.The plasma CXCL10 level in patients with CTEPH was significantly higher than that in healthy controls matched with sex and age,and decreased with the improvement of pulmonary hemodynamics after BPA treatment.Plasma CXCL10 levels in patients with CTEPH were significantly correlated with pulmonary hemodynamics and NT-pro BNP.There are a large number of CD68 positive macrophages with high expression of CXCL10 in the pulmonary artery intima tissue of CTEPH patients.2.Left pulmonary artery ligation can cause a significant increase in right ventricular systolic pressure and right heart hypertrophy index in rats,leading to thickening of the smooth muscle layer of the peripheral pulmonary arterioles in the right lung and infiltration of inflammatory cells around the arteries.The expression levels of CXCL10 and CXCR3 in the right lung tissue of LPAL rats increased,and the plasma CXCL10 levels increased.There is a large number of CD68 positive macrophages with high expression of CXCL10 infiltrating around the right pulmonary arteriole of LPAL rats.The proliferation and migration of smooth muscle cells in the right pulmonary artery of LPAL rats are enhanced.3.CXCR3 antagonist AMG487 can improve right ventricular systolic blood pressure and right ventricular hypertrophy index in LPAL rats,and improve peripheral pulmonary vascular remodeling.AMG487 can significantly downregulate the expression levels of CXCL10 and CXCR3 in the right lung tissue of LPAL rats,and reduce the plasma CXCL10 level of LPAL rats.In vivo administration of AMG487 can significantly inhibit the proliferation and migration of smooth muscle cells in the right pulmonary artery of LPAL rats.In vitro administration of exogenous CXCL10 to LPAL rat PASMC can significantly promote its proliferation and migration,while AMG487 can significantly inhibit the abnormal proliferation of LPAL rat PASMC caused by exogenous CXCL10,which may be related to the abnormal increase in CXCR3 expression level in right lung PASMC of LPAL rat.【Conclusion】1.Plasma CXCL10 levels in patients with CTEPH increased significantly,and decreased with the improvement of pulmonary hemodynamics after BPA treatment.2.There is a large number of CD68 positive macrophages with high expression of CXCL10 in the pulmonary artery intima tissue of CTEPH patients.3.Subcutaneous injection of CXCR3 antagonist AMG487 can significantly improve right ventricular systolic pressure and right ventricular hypertrophy index in LPAL rats,and improve peripheral pulmonary vascular remodeling.4.AMG487 can significantly downregulate the expression levels of CXCL10 and CXCR3 in the right lung tissue of LPAL rats,and reduce the plasma CXCL10 level of LPAL rats.5.In vitro administration of exogenous CXCL10 to LPAL rat PASMC can significantly promote cell proliferation and migration,while AMG487 can significantly inhibit the abnormal proliferation of LPAL rat PASMC caused by exogenous CXCL10,which may be related to the abnormal increase in CXCR3 expression level in the right lung PASMC of LPAL rats.