神经母细胞瘤抑瘤蛋白1（NBL1）在先天性心脏病肺动脉高压肺血管重构中的作用及分子机制

Researches confirmed that mutations in BMPRⅡ cause the genesis of pulmonary arterial hypertension, however, BMPRⅡmutations in congenital heart diseases associated pulmonary arterial hypertension(CHD/PAH) have the lowest frequency, so the underling mechanisms of the downregulation of BMP signal pathway in CHD/PAH require further investigation. Through an antibody microarray procedure, we found that, comparing with those of the normal age- and gender-matched subjects, the plasma levels of one of the BMP antagonists, NBL1, were significantly up-regulated in patients with CHD/PAH, furthermore, immunohistochemistry also confirmed that NBL1 demonstrated a conspicuous augmentation in the remodeled pulmonary arteries/arterioles in lungs from patients with CHD/PAH. Therefore, we proposed that NBL1 is possibly involved in the genesis and/or the progression of CHD/PAH. This study attempts to further investigate：① the alteration trend of the mRNA and protein level of NBL1 in lung tissues with the progression of PAH induced by systemic-to-pulmonary shunt，and the correlation between the plasma level of NBL1 and pulmonary hemodynamic index and the extent of pulmonary pathological lesions.; ② the effects of NBL1 on the proliferation，migration and apoptosis of human pulmonary arterial smooth muscle cells and endothelial cells, and the BMP signal pathway; ③the impact of blocking the endogenous NBL1 on the progression of PAH induced by systemic-to-pulmonary shunt. Conclusively, this study aims to investigate the mechanism of NBL1 involved in the remodeling process of pulmonary artery/arterioles and the potential of NBL1 to be a promising treatment target for CHD/PAH, especially, to provide an alternative elucidation for the BMP signaling reduction in lung tissues from CHD/PAH.

研究证实骨形态发生蛋白Ⅱ型受体(BMPRⅡ)突变导致肺动脉高压的发生, 而先天性心脏病肺动脉高压(CHD/PAH) BMPRⅡ突变率最低，但其BMP信号通路显著下调且机制不明。本研究通过蛋白抗体芯片筛选发现CHD/PAH患者BMP拮抗因子NBL1血浆浓度显著升高；组织化学显示CHD/PAH重构的肺血管强表达NBL1，因此推测升高的NBL1通过拮抗BMP参与CHD/PAH进程。本研究拟探讨: ①在持续的体-肺分流刺激下，大鼠肺组织NBL1和BMP信号通路表达水平的变化及NBL1血浆浓度与肺血流动力学指标和肺血管重构程度的相关性；②NBL1抑制BMP活性，调节人肺动脉内皮和平滑肌细胞增殖、迁移、凋亡及对BMP信号通路的影响；③在体阻断NBL1对PAH的影响。本研究旨在揭示NBL1参与CHD/PAH肺血管重构的机制及其作为干预靶点的可行性，特别是CHD/PAH肺组织BMP信号通路下调的新机制。

背景：生理状态下，分泌型蛋白质神经母细胞瘤抑瘤蛋白1（ NBL1）主要表达在正常肺组织，而在体-肺分流的病理状态下NBL1表达水平显著下降，提示NBL1应该是先天性心脏病肺动脉高压潜在的研究靶点。本课题拟研究分泌型蛋白质NBL1在先天性心脏病肺动脉高压中的作用。.方法及结果：本研究通过外科技术，采取右肺动脉结扎术+左侧颈部体-肺分流术的方法在SD大鼠上诱导出体-肺分流性肺动脉高压状态及显著的肺血管重构病变，而实时PCR及蛋白印迹显示NBL1的表达水平在正常肺组织中要明显高于体-肺分流性肺组织；免疫组织化学分析显示NBL1在正常肺小动脉血管壁高表达而在严重重构的肺小动脉血管壁很少发现。同时发现在体-肺分流状态下NBL1的血浆浓度显著降低且与肺血流动力学指标（RVSP, PASP, mPAP ）及右室肥厚指数显著负相关。NBL1还可显著逆转BMP2/4对肺动脉内皮细胞及肺动脉平滑肌细胞的增殖抑制作用，但对肺动脉平滑肌细胞及肺动脉内皮细胞的增殖没有直接作用，另外NBL1还可以通过阻断PDGFβ-p38MAPK信号通路抑制PDGF-BB诱导的肺动脉平滑肌细胞的增殖；而从肺动脉血流动力学指标，右室肥厚程度及肺血管重构程度的角度来说，持续补充重组NBL1蛋白可引起体-肺分流性肺动脉高压程度的恶化。.结论：NBL1在体-肺分流性肺组织中的表达水平的显著下调可延缓体-肺分流相关肺动脉高压的进展，而这种作用至少部分是通过NBL1拮抗BMP信号通路及PDGFβ-p38MAPK信号通路实现的。因此NBL1或是先天性心脏病肺动脉高压潜在的治疗靶点及候选的新型生物标记物。