分泌型蛋白质GREM1在体-肺分流性肺动脉高压中的作用

Role of secretory protein GREM1 in systemic-to-pulmonary shunt associated pulmonary arterial hypertension

目的探讨骨形态发生蛋白(BMP)拮抗因子GREM1作为先天性心脏病相关肺动脉高压(CHD/PAH)患者BMP信号通路活性下调机制的可能。方法外科手术建立大鼠体-肺分流性PAH模型。术后12周,右心导管及心脏超声测量右心系统血流动力学指标及形态学指标,心、肺、血标本取材。计算右心肥厚指数,评估肺血管重构情况,检测肺组织BMP信号通路相关蛋白及GREM1的表达变化及血浆GREM1浓度。体外培养肺动脉内皮细胞(PAECs),研究GREM1对PAECs增殖及凋亡的影响。结果体-肺分流大鼠模型成功再现了CHD/PAH的PAH状态。在分流性肺组织中,缺氧诱导因子-1α(HIF-1α)表达水平无改变(P>0.05),GREM1表达增加,但BMP信号通路组份的表达下降(P<0.05),而矫正体-肺分流可逆转这一趋势(P<0.05)。免疫组织化学染色显示重构的肺小动脉中GREM1表达增加(P<0.05)。体外细胞实验显示,增殖的PAECs中BMP信号通路相关蛋白下调而GREM1表达和分泌显著升高(P<0.05),且GREM1通过拮抗BMP信号通路显著促进PAECs的增殖并抑制其凋亡(P<0.05)。此外,体-肺分流大鼠的血浆GREM1显著升高且与肺血流动力学参数密切相关(P<0.05)。结论体-肺分流引起肺组织GREM1表达升高,而升高的GREM1通过下调BMP信号通路活性诱导肺血管重构,促进肺动脉高压的形成。此研究结果为CHD/PAH肺组织BMP信号通路活性下调机制提供了一种新的解释。

Objective To explore the possibility that GREM1,a bone morphogenetic protein(BMP)antagonist,is a mechanical explanation for BMP signal suppression in congenital heart disease associated pulmonary arterial hypertension(CHD/PAH)patients.Methods Systemic-to-pulmonary shunt induced PAH was surgically established in rats.At the postoperative 12th week,right heart catheterization and echocardiography evaluation were performed to evaluate hemodynamic indexes and morphology of right heart system.Right heart hypotrophy index and pulmonary vascular remodeling were evaluated.Changes of BMP signal pathway related proteins and GREM1 in lungs and plasma GREM1 concentration were detected.The effect of GREM1 on the proliferation and apoptosis of pulmonary arterial endothelial cells(PAECs)was also explored.Results The hypertensive status was successfully reproduced in rats with systemic-to-pulmonary shunt model.BMP signal pathway was suppressed but GREM1 was up-regulated with no change in hypoxia inducible factor-1 in lungs exposed to systemic-to-pulmonary shunt,while this trend was reversed by systemicto-pulmonary shunt correction(P<0.05).Immunohistochemical staining demonstrated enhanced staining of GREM1 in remodeled pulmonary arteries.In vitro experiments found that BMP signal was down-regulated but GREM1 expression and secretion were up-regulated in proliferative PAECs(P<0.05).Furthermore,BMP2 significantly inhibited PAECs proliferation and promoted PAECs apoptosis(P<0.05),which could be antagonized by GREM1.In addition,plasma level of GREM1 in rats with systemic-to-pulmonary shunt was also increased and positively correlated with pulmonary hemodynamic indexes.Conclusion Systemic-to-pulmonary shunt induces the up-regulation of GREM1 in lungs,which promotes pulmonary vascular remodeling via antagonizing BMP cascade.These results present a new mechanical explanation for BMP pathway suppression in lungs of CHD/PAH patients.