Role Of NADPH Oxidase (NOX4) Involved In Pulmonary Arterial Smooth Muscle Remodeling In Chronic Obstructive Pulmonary Disease

Objective:To investigate the role of NOX4 in small arteriolar remodeling of Chronic Obstructive Pulmonary Disease（COPD）.To evaluate the relationship between COPD pulmonary small arterial remodeling with pulmonary artery hemodynamics parameters and the right ventricular function parameters under cardiac magnetic resonance imaging（CMR）,transthoracic doppler echocardiography（TDE）measurement.Method:34 patients who were about to undergo lobectomy for suspected primary lung cancer were recruited in the General Hospital of Ningxia Medical University.Accoding to the results of chest CT scan and lung function examination,15 lung tumor patients combination with COPD（COPD group）and 19 lung tumor patients with normal lung function（control group）.6-minute walk test,transthoracic Doppler echocardiography,cardiac magnetic resonance imaging test were done before the surgery.At the same time blood sample were collected before the surgery for serum endothelin 1（ET-1）,malondialdehyde（MDA）,superoxide dismutase（SOD）measurement.A portion of grossly normal lung tissue was collected from the distal end of lesion during the operation process.Lung tissues were processed for paraffin embedding and/or embedded in optimal cutting temperature compound.And further cut for hematoxylin and eosin（HE）,histochemistry（includes immunohistochemistry,IHC）and characters of pulmonary arterioles were marked bymodified Weigert elastic fiber staining,the localization and expression of NOX4,а-SMA and PCNA in the pulmonary arterioles were observed by immunohistochemistry and dual immunofluorescence and Western blottling and Real-time Quantitative PCR Detecting System.Results:1.Pulmonary arteriolar remodeling and the expression of NOX4 expression of COPD patients as follows（1）pulmonary artery smooth muscle（WT）,pulmonary artery smooth muscle thickness accounted for the percentage of vascular diameter（WT%）,pulmonary artery smooth muscle area accounted for the percentage of total vascular area（WA%）was（37.07±18.07）μm,（64.76±19.48）%,（55.38±23.46）%in COPD group respectively and which were significantly higher than those（18.71±3.35）μm,（29.17±5.36）%,（39.67±6.78）%in control group respectively,the difference was statistically significant（P<0.05）.（2）The expression of NOX4andа-SMA in Pulmonary arteriolar smooth muscle:the results of immunohistochemistry and and Western blottling and Real-time Quantitative PCR Detecting System showed that the expression of NOX4 andа-SMA in COPD group were higher than that in control group（P<0.05）.（3）The expression of proliferating cell nuclear antigen（PCNA）in the Pulmonary arteriolar smooth muscle cells of COPD group was（33.78±11.24）%which was significantly higher than that in the control group（10.72±7.19）%（P<0.01）.（4）The correlation analysis shows:WA%,WT%were negatively correlated with forced expiratory volume in one second/forced vital capacity（FEV1/FVC）and forced expiratory volume in one second total predicted value（FEV1%pred）respectively（P<0.01）.The expression of NOX4 in pulmonary arteriolar was negatively correlated with FEV1/FVC and FEV1%pred respectively（P<0.05）,and was positively correlated with the expression of WA%,WT%and PCNA respectively（P<0.05）.2.Pulmonary arterial hemorheology and right ventricular function parameters under CMR are as follows,the maximum main pulmonary artery diameter（mPADmax）,minimum main pulmonary artery diameter（mPADmin）,maximum cross-sectional area（CSAmax）,minimum cross-sectional area（CSAmin）,average negative flow（ANF）,regurgitant fraction（RF%）,right ventricular myocardial mass end-diastolic（RVMED）,right ventricular myocardial mass end-systolic（RVMES）,ventricular myocardial mass index（VMI）were significantly higher in the COPD group than that in the control group（P<0.05）.The main pulmonary artery strongly（mPAD%）in COPD group was（43.82±10.87）%which was significantly lower than that in the control group（57.29±14.47）%（P<0.05）.mPAD%was positively correlated with FEV1/FVC and FEV1%pred respectively（P<0.05）,RF%was negatively correlated with FEV1/FVC and FEV1%pred respectively（P<0.05）;RVMED was negatively correlated with PO₂（P<0.05）and positively correlated with PCO₂（P<0.05）respectively.3.Oxidative stress indicators in the serum of patients with COPD:The levels of serum ET-1and MDA in COPD group was（10.49±4.79）pg/ml,（1406.62±360.63）ng/ml respectively and which were significantly higher than those（6.61±3.23）pg/ml,（1156.71±185.58）ng/ml in control group respectively,the difference was statistically significant（P<0.05）.The level of SOD in COPD group was（164.41±59.72）ng/ml which was significantly lower than that in control group（222.37±63.94）ng/ml,the difference was statistically significant（P<0.05）.Conclusion:1.An increased ASM mass and enhanced of cell proliferation activity of pulmonary artery smooth muscle cells were common in COPD patients Such ahyperreactivity or remodeling of pulmonary artery smooth muscle was enhanced with cell proliferative capacity and disease severity.2.The expression of NOX4 in the pulmonary arteriolar smooth muscle cells in COPD group was significantly higher than that in the control group and the expression of NOX4 was positively correlated with the severity of air flow limitation and was positively correlated with the remodeling of pulmonary arteriolar smooth muscle,suggesting that NOX4 may be involved in the development of pulmonary arteriolar remodeling of COPD in unknown signaling pathway.3.COPD patients with elevation in the main pulmonary artery area and the negative flow and decrease in the main pulmonary artery strongly.At the same time COPD patients with elevation in right ventricular myocardial mass.Suggesting that pulmonary arteriolar remodeling will affect the main pulmonary artery hemorheology in COPD patients and further affect the structure of right heart myocardial,Suggesting that the pulmonary arteriolar remodeling and pulmonary rheological changes even right heart myocardial structural changes were observed in COPD patients although they did not have clinical pulmonary hypertension.4.COPD patients with increased circulating oxidative stress products and decreased antioxidant substances,suggesting that oxidative stress may play a significant role in the pathogenesis of COPD,including the vascular remodeling.