PAH血管重塑新靶点半乳凝素-3在肺血管平滑肌细胞中的功能及其作用机制研究

Progressive inward hypertrophic remodeling of pulmonary arteries is a defining characteristic of pulmonary arterial hypertension (PAH) and the therapeutic strategy of lowering pulmonary vascular resistance by reducing vascular tone is only temporarily effective and eventually failure of the right ventricle and death. Multiple signaling pathways which are involved in cellular proliferation, inflammation and fibrosis can cause pulmonary vascular remodeling in PAH, however the mechanisms are not yet well understood. Galectins are b-galactoside binding lectins that have been implicated as a nodal regulator of multiple signaling pathways involved in cellular proliferation, inflammation and fibrosis. We have found a member of Galectin proteins Galectin-3 (Gal-3) expression is increased in pulmonary vascular smooth muscle cells in remodeled PA. In cultured human pulmonary artery vascular smooth muscle cells (HPAVSMC), upregulation of Gal-3 expression promotes whereas inhibition of Gal-3 reduces proliferation, fibrosis and inflammation. However, the therapeutic utility of targeting Gal-3 in PAH and the mechanisms by which it influences pulmonary vascular remodeling are not yet known. This application will address the deficits in our knowledge by: 1) establishing a functional role of Gal-3 in the pathogenesis of PAH, 2) identifying the molecular regulatory mechanism of Gal-3 in pulmonary artery vascular smooth muscle cells in vascular remodeling, 3) exploring the significance of this pathway in PAH and its translational potential in PAH. We anticipate the development of novel therapeutic agents targeting Gal-3 that will help reduce pulmonary arterial remodeling and subsequently improving the morbidity and mortality associated with PAH.

肺动脉高压（PAH）是一个进行性发展高死亡率的恶性疾病，表现为肺血管重塑和肺动脉高压。血管重塑表现为血管肌化、炎症和纤维化，目前缺乏有效治疗方案。本课题初步研究表明，半乳凝素-3（Gal-3）表达在3种不同的PAH模型肺动脉中明显升高，在动物和人的PAH动脉中膜平滑肌细胞Gal-3大量产生。在人肺动脉血管平滑肌细胞中，抑制Gal-3可以明显减少细胞增殖，纤维化和炎症反应。然而，Gal-3影响肺血管重塑的机制以及将Gal-3作为早期诊断和治疗靶点的价值还不清楚。本研究旨在1）证实Gal-3在PAH血管重塑中的作用，2）研究Gal-3在血管平滑肌细胞及其临近细胞中的作用及调控机制，3）探索Gal-3抑制剂在PAH治疗中的应用价值及意义。本项目的完成将有助于了解Gal-3在血管重塑中的作用、明确其在PAH中的转化潜力，发展Gal-3新型治疗药物将有助于逆转血管重塑，降低PAH发病率和病死率。

肺动脉高压（PAH）是一个进行性发展高死亡率的恶性疾病，表现为肺血管重塑和肺动脉高压，最终诱发右心衰而致死亡。血管重塑是起源于血管管壁的病变，表现为血管肌化、炎症和纤维化，其发生机制不清，目前缺乏逆转肺血管重塑的有效方案。本项目在细胞分子水平、整体动物和临床样本中开展研究工作，深入解析了半乳凝素-3（Galectin-3, Gal-3）信号通路分子在PAH发生发展中的作用及其分子机制。本课题研究表明，Gal-3的表达在3种不同的PAH模型肺动脉中明显升高，动物和人的PAH动脉中膜平滑肌细胞是Gal-3重要来源。在MCT诱导的PAH实验动物模型中，Gal-3特异性抑制剂能有效阻止并逆转肺动脉血管重塑、右心室肥厚，并改善血流动力学；在MCT和缺氧诱导的大鼠PAH模型中敲除Gal-3表达同样能够阻止并逆转肺动脉血管重塑、右心室肥厚，并改善血流动力学。体内和细胞水平实验证实，抑制Gal-3显著降低细胞增殖和相关分子Ki-67(MKi-67)，cyclin-dependent kinase 1(CDK1)和cyclin A2(CCNA2)的表达水平，cleaved caspase3水平检测和TUNEL染色表明Gal-3参与了细胞凋亡调控的重要分子机制，抑制Gal-3可以显著降低纤维化及相关分子标记CD90，VCAN，Col1A，thrombspondin-4，periostin和vimentin的基因表达水平。本课题还深入探索了Gal-3调控肺血管平滑肌细胞增殖，纤维化和炎症的具体分子机制，研究发现Gal-3对肺血管平滑肌细胞行为的调控可能通过影响下游分子Erk，STAT1，STAT3，Akt和FAK的磷酸化水平发挥作用，并可能与其参与的对Nox1-5基因表达水平和细胞内氧化应激水平的调控密切相关。在PAH临床样本中，利用备用候选基因关联研究的遗传学策略筛选了包括Gal-3在内的14个基因的143个TagSNP多态性与PAH的关联，结果并没有发现与PAH显著相关的Gal-3 TagSNP，提示可能与候选的SNP筛选和临床样本量不够有关，未来将利用全基因组关联在更大样本上开展研究。本项目明确了Gal-3在血管重塑中的作用、证实了其在PAH治疗方面的潜在价值，发展针对Gal-3新型治疗药物将有助于减轻或逆转肺血管重塑，降低PAH的发病率和病死率。