Phenotypically Silent Bone Morphogenetic Protein Receptor 2 Mutations Predispose Rats to Inflammation-Induced Pulmonary Arterial Hypertension by Enhancing the Risk for Neointimal Transformation
Phenotypically Silent Bone Morphogenetic Protein Receptor 2 Mutations Predispose Rats to Inflammation-Induced Pulmonary Arterial Hypertension by Enhancing the Risk for Neointimal Transformation
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DOI：
10.1161/circulationaha.119.040629
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发表时间：
2019-10-22
期刊：
影响因子：
37.8
通讯作者：
Nicolls, Mark R.
中科院分区：
文献类型：
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作者：
Tian, Wen;Jiang, Xinguo;Nicolls, Mark R.
背景资料：Bmpr 2（骨形态发生蛋白受体2）突变是遗传性肺动脉高压（PAH）的关键风险因素，约20%的携带者发生疾病。有一个未满足的医学需求，以了解环境因素，如炎症，使Bmpr 2突变体对PAH敏感。过度表达5-LO（5-脂氧合酶）在Bmpr 2（+/-）小鼠中引起肺部炎症和短暂PAH。因此，5-LO及其代谢物白三烯B-4是第二次命中的候选物。本研究的目的是确定5-LO介导的肺部炎症如何与表型沉默的Bmpr 2缺陷协同作用，以引起大鼠显著的肺血管疾病。方法：产生单等位基因Bmpr 2突变大鼠，并观察长达1年，发现表型正常。为了评估第二次打击是否会引发疾病，将动物暴露于5-LO表达腺病毒、野百合碱、SU 5416、SU 5416伴慢性缺氧或仅慢性缺氧。评估Bmpr 2突变型遗传性PAH患者样本的新生内膜5-LO表达。将BMPR 2信号传导受损的肺动脉内皮细胞暴露于增加的5-LO介导的炎症，并评估表型和转录组学变化。结果如下：在Bmpr 2（+/-）大鼠中，通过气管内递送表达5-LO的腺病毒诱导的肺部炎症引起严重的PAH伴内膜重塑，但在其野生型同窝仔中没有。患病Bmpr 2（+/-）大鼠的新生内膜病变获得与升高的白三烯B-4生物合成相关的内源性5-LO表达。Bmpr 2突变型遗传性PAH患者在新生内膜细胞中表达类似的5-LO。在体外，BMPR 2缺陷，5-LO介导的炎症，产生的肺动脉内皮细胞间充质特性的耐肺动脉炎和增殖。这些转化细胞表达与诱导的白三烯B-4产生一致的核定位5-LO，以及与临床疾病相似的转录组学特征，包括上调的核因子κ B亚基（NF-κ B）、白细胞介素-6和转化生长因子β（TGF-β）信号传导途径。通过TGF-β拮抗作用逆转Bmpr 2突变体中的PAH和血管病变表明TGF-β对新生内膜转化至关重要。结论：在一种新的2-hit疾病模型中，肺部炎症在Bmpr 2（+/-）大鼠中诱导了严重的PAH病理。内皮细胞转化需要激活经典和非经典TGF-β信号通路，其特征在于5-LO核膜易位和增强的白三烯B-4产生。这项研究解释了环境伤害如何释放原本沉默的基因突变的破坏性潜力。
Background: Bmpr2 (bone morphogenetic protein receptor 2) mutations are critical risk factors for hereditary pulmonary arterial hypertension (PAH) with approximately 20% of carriers developing disease. There is an unmet medical need to understand how environmental factors, such as inflammation, render Bmpr2 mutants susceptible to PAH. Overexpressing 5-LO (5-lipoxygenase) provokes lung inflammation and transient PAH in Bmpr2(+/-) mice. Accordingly, 5-LO and its metabolite, leukotriene B-4, are candidates for the second hit. The purpose of this study was to determine how 5-LO-mediated pulmonary inflammation synergized with phenotypically silent Bmpr2 defects to elicit significant pulmonary vascular disease in rats. Methods: Monoallelic Bmpr2 mutant rats were generated and found phenotypically normal for up to 1 year of observation. To evaluate whether a second hit would elicit disease, animals were exposed to 5-LO-expressing adenovirus, monocrotaline, SU5416, SU5416 with chronic hypoxia, or chronic hypoxia alone. Bmpr2-mutant hereditary PAH patient samples were assessed for neointimal 5-LO expression. Pulmonary artery endothelial cells with impaired BMPR2 signaling were exposed to increased 5-LO-mediated inflammation and were assessed for phenotypic and transcriptomic changes. Results: Lung inflammation, induced by intratracheal delivery of 5-LO-expressing adenovirus, elicited severe PAH with intimal remodeling in Bmpr2(+/-) rats but not in their wild-type littermates. Neointimal lesions in the diseased Bmpr2(+/-) rats gained endogenous 5-LO expression associated with elevated leukotriene B-4 biosynthesis. Bmpr2-mutant hereditary PAH patients similarly expressed 5-LO in the neointimal cells. In vitro, BMPR2 deficiency, compounded by 5-LO-mediated inflammation, generated apoptosis-resistant and proliferative pulmonary artery endothelial cells with mesenchymal characteristics. These transformed cells expressed nuclear envelope-localized 5-LO consistent with induced leukotriene B-4 production, as well as a transcriptomic signature similar to clinical disease, including upregulated nuclear factor Kappa B subunit (NF-kappa B), interleukin-6, and transforming growth factor beta (TGF-beta) signaling pathways. The reversal of PAH and vasculopathy in Bmpr2 mutants by TGF-beta antagonism suggests that TGF-beta is critical for neointimal transformation. Conclusions: In a new 2-hit model of disease, lung inflammation induced severe PAH pathology in Bmpr2(+/-) rats. Endothelial transformation required the activation of canonical and noncanonical TGF-beta signaling pathways and was characterized by 5-LO nuclear envelope translocation with enhanced leukotriene B-4 production. This study offers an explanation of how an environmental injury unleashes the destructive potential of an otherwise silent genetic mutation.