The Role Of Nuclear Factor-κB And Its Inhibitor PDTC In Pulmonary Arterial Hypertension

Objective The main pathomechanisms of pulmonary arterial hypertension are vascular constriction,remodeling and thrombosis.A lot of studies have revealed that inflammatory reaction and inflammatory factors are highly related to pulmonary vascular constriction,remodeling and thrombosis.Nuclear factor-κB(NF-κB),a transcription factor,plays a significant role on immune response and inflammation,after activation,NF-κB can start and control a series of inflammatory factors expression.Intercellular adhesion molecule-1(ICAM-1) is one of downstream products after activation of NF-κB.ICAM-1 participates in and mediats adhesion of cell-cell and cell-extracellular matrix,it is the basis of inflammatory reaction.This study aims to investigate changes and functions of nuclear factor-κB(NF-κB) and its inhibitor PDTC in monocrotaline(MCT)-induced pulmonary arterial hypertension (PAH).Methons1.Pulmonary arterial hypertension rats model was established by injecting the toxin MCT.There were 58 Wistar rats.2.Before and 1,2 and 3 weeks after MCT injection(randomly choose 8rats at each time point,recoded as MCT₀group,MCT_1W group,MCT_2W group and MCT_3W group ),rats were underwent mean right ventricular pressure(mRVP) measurements with right cardiac catheterization.Indexes of right ventricular hypertrophy were calculated by measurement ratio of right ventricle(RV) to left ventricle plus septum(LV+S).The index of wall thickness of pulmonary arteriole was measured by a computerized image analyzer.Expression of intercellular adhesion molecule-1(ICAM-1) and Macrophage infiltration in lung tissues were detected before and after injection by immunohistochemistry.3.Next,26rats were randomly divided into three groups:MCT/vehicle group(rats injected with MCT and treated with saline solution from the second day after MCT injection,n=9),MCT/PDTC group(rats injected with MCT and treated with PDTC from the second day after MCT injection,n=9),control/vehicle group(controls similarly treated with saline solution[control/vehicle group,n=8).Three weeks later, rats were underwent mean right ventricular pressure(mRVP) measurements with right cardiac catheterization.Indexes of right ventricular hypertrophy were calculated by measurement ratio of right ventricle(RV) to left ventricle plus septum(LV+S).The index of wall thickness of pulmonary arteriole was measured by a computerized image analyzer.Activity of NF-κB in lung tissues was confirmed by electrophoretic mobility shift assays(EMSA).Expression of intercellular adhesion molecule-1 (ICAM-1) and Macrophage infiltration in lung tissues were detected by immunohistochemistry.Results1.The mean right ventricular pressure and index of right ventricular hypertrophy barely changed at 1week after MCT injection,they were remarkably higher at 2 weeks after MCT injection than before injection(P<0.01) and were more higher at 3 weeks after MCT injection(P<0.01).2.WT%and WA%of pulmonary medial arteries and arteriole barely changed at 1 week after MCT injection,they were remarkably higher at 2weeks after MCT injection than before injection(P<0.01) and were more higher at 3weeks aider MCT injection(P< 0.01).3.The expression of ICAM-1 was observed in the pulmonary vascular endothelium. In quantitative analysis of immunohistochemical findings,the endothelial expression of ICAM-1 was significantly up-regulated on weeks 1,2 and 3after injection(P<0.01) Macrophage Infiltration were significantly up-regulated in the endothelium of diseased vessels from week 1after injection(p<0.01). 4.Another 26rats,Compared to controls,MCT treatment increased the mean right ventricular pressure(MCT/vehicle group,27.8±1.5mm Hg;control/vehicle group,17.2±1.4mm Hg,P<0.01)and indexes of right ventricular hypertrophy (MCT/vehicle group,0.56±0.05;control/vehicle group,0.26±0.02;P<0.01)). MCT treatment significantly increased the activity of NF-κB(MCT/vehicle group, 458±12.8;control/vehicle group,265±17.6;P<0.01),the expression of ICAM-1 in the endothelium of pulmonary vessels(MCT/vehicle group,2.20±0.50; control/vehicle group,0.20±0.41;P<0.01) and the number of CD68-positive cells in the adventitia of diseased vessels(MCT/vehicle group,225±10.6 per 30 high-power fields;control/vehicle group,48±6.8 per 30 high-power fields;P< 0.01).5.Compared to controls,PDTC treatment reduced the mean right ventricular pressure(MCT/PDTC group,18.4±2.2mm Hg;MCT/vehicle group,27.8±1.5mm Hg,P<0.01)and indexes of right ventricular hypertrophy(MCT/PDTC group, 0.28±0.03;MCT/vehicle group,0.56±0.05;P<0.01).PDTC treatment significantly decreased the activity of NF-κB(MCT/PDTC group,458±12.8;MCT/vehicle group,265±17.6;P<0.01),the expression of ICAM-1 in the endothelium of pulmonary vessels(MCT/PDTC group,0.32±0.55;MCT/vehicle group,2.20±0.50; P<0.01)and the number of CD68-positive cells in the adventitia of diseased vessels(MCT/PDTC group,54±8.7 per 30high-power fields;MCT/vehicle group, 225±10.6 per 30 high-power fields;P<0.01).Conclusions We concluded that the NF-κB activity and ICAM-1 expression is probably associated with the development of MCT-induced PAH,which was ameliorated by administering a NF-κB inhibitor,PDTC.