| Background and Objective:Pulmonary arterial hypertension(PAH)is a major reason of death in patients of Systemic sclerosis(SSc).As its insidious onset,untypical clinical manifestation,difficulty of early diagnosis and dissatisfied treatment results,the early diagnosis,treatment and prognosis evaluation of SSc-PAH is still an important problem for rheumatology physician at present.PAH is one of the worst prognostic diseases in SSc-related lung diseases.Its pathological changes are related to endothelial dysfunction and local inflammation.In its later stage,PAH is an over-proliferation and decreased apoptosis of pulmonary vascular smooth muscle cells.In the pathogenesis of PAH,Endothelin-1(ET-1)plays a pivotal role.ET-1 is a 21 peptide synthesized by vascular endothelial cells,as a strong and sustained vasoconstrictor,it also actively involved in hypertrophy and fibrosis of vascular wall.ET1 is through its receptor(Endothelin receptor,ETR)(type A receptor,type B receptor)pathway to play the role of vasoconstrictor,the Endothelin Receptor Type A(ETRA)located in pulmonary artery smooth muscle cells and vascular endothelial cells is a major factor in triggering vascular contraction,and plays an important role in the regulation of cell proliferation and pulmonary immune microenvironment.This study is designed to detect the positive rate and specificity of anti-Endothelin Receptor Type A Autoantibodies(ETRA-Ab)in SSc-PAH and to observe the relationship between incidence and severity of SSc-PAH and ETRA-Ab.Then to investigate the possibility of ETRA-Ab as an early biomarker for early diagnosis of SSc-PAH.And further confirm the role that ETRA-Ab plays as a functional antibody in the course of PAH by animal experiments.Method:1?Observation of clinical indexes: A total of 24 SSc-PAH samples and 24 cases of SSc non-PAH and 24 normal controls were included.And recorded the clinical data.Detected pulmonary artery systolic pressure(PASP)diagnosed by cardiothoracic ultrasonography,among then five cases of SSc-PAH were examined by right cardiac catheterization.The 6 minute walking distance(6MWD)was measured in each group.The ETAR antibody in the plasma of each group was detected by enzyme-linked immunosorbent assay(ELISA),and the positive rate was calculated.2? Establishment of Monocrotatine(MCT)pulmonary hypertension rat models: a total of 34 male SD rats were enrolled in this study,we performed a randomized trial of control group vs experimental group(n=10).In the experimental group,MCT was used to build the model,randomly divided into MCT group and MCT+ETRA-Ab group(n=12).In MCT+ETRA-Ab group,the rats were injected with ETRA-Ab polyclonal IgG antibody via tail vein for three times a week at first week to third week of modeling.3?Mensuration of the mean pulmonary arterial pressure(mPAP): At the 4th week after MCT modeling,the right external jugular vein was intubated and the mPAP was measured with Medlab-E biological function signal acquisition system.And SPSS20.0 was used to analyze the differences between groups.4?Mensuration of the right ventricular hypertrophy index(RVHI %): Removed the heart and then separated the left and right ventricle and the interventricular septum.Weighed the quality of the right ventricular wall(RV)and the quality of the left ventricle and the interventricular septum(LV+S),then calculated of right heart hypertrophy index(=RV/(LV+S))and analyzed differences between the groups.5? Observation of the pulmonary vascular morphology: Cut the whole upper lobe of right lung,formaldehyde fixed,dehydrated,dipped in wax,embedded,sliced,dried,HE stained.And the morphological changes of pulmonary arterioles were observed under light microscope.Then compared the changes of proportions of muscular artery(MA),partial muscular artery(PMA)and non-muscular artery(NMA)pulmonary vascular between the two groups.6?Detection of the plasma inflammatory cytokines: Interleukin(IL)-6 and tumor necrosis factor TNF –?were detected,and then the differences between the groups were analyzed.Result:1?The positive rate of ETRA antibody in SSc-PAH group was 50% and the SSc non PAH group was 12.5%,and the positive rate of ETRA antibody in normal control group was 0%.There was significant difference in positive rate(P<0.01).2?The level of ETRA-Ab antibody in serum of patients with SSC-PAH was correlated with PASP(r=0.3439 P=0.0321).However,there was a significant negative correlation between the level of ETRA antibody titer and 6MWD test(r=-0.3221 P=0.0391),and correlated with NT-proBNP results(r=0.3335 P=0.0318).3?At the fourth week established MCT model,the comparison of mPAP(mmHg)among injection of 10% chloral hydrate,anesthesia abdominal and cavity external jugular vein intubation :normal control group(17.3±1.1).MCT group(30.8±2.0),MCT+ETRA-Ab group(34.5±3.1)(P<0.05).4?The RVHI % was compared between the two groups in separated of right ventricle after pressure measured of animals: the group of MCT(0.355±0.051),the other group of MCT+ETRA-Ab(0.402±0.049)(P<0.05).5?The proportions of MA,PMA and NMA in three groups(PMA?PPMA?PNMA)were compared by HE staining in lung tissue : The PMA and PMMA in MCT + ETRA-Ab group were higher than those of MCT control group(P <0.05),both of which were significantly higher than those in normal control group.6?Mensuration of the inflammatory factor :the level of IL-6?TNF-?in MCT group and MCT+ETRA-Ab group were significantly higher than the normal control group.And the MCT+ETRA-Ab group was more significant than that of MCT group.conclusion1?ETRA-Ab has a good sensitivity and high specificity for the diagnosis of SSc-PAH,suggesting that ETRA-Ab can be used as a new biomarker for early diagnosis of SSc-PAH.2 ? ETRA-Ab titer was positively correlated with PASP,NT-proBNP and microcirculation index and negatively correlated with distance of 6MWD.the results suggesting that ETRA-Ab titer can be used as an indicator to evaluate the prognosis of patients.3?ETRA-Ab was positively correlated with the hemodynamic indexes and right ventricular hypertrophy index and pulmonary vascular morphology of MCT rats,and it up regulated inflammatory factor IL-6 and TNF-?suggesting that ETRA-Ab can participate in many aspects such as pulmonary vascular remodeling and right ventricular hypertrophy as functional antibody. |
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