黄芩苷对缺氧诱导肺动脉内皮细胞转分化的作用及机制研究

There is no ideal treatment for pulmonary arterial hypertension (PAH) that is closely associated with transdifferentiation of pulmonary arterial endothelial cells (PAECs). Baicalin can protect endothelial cells from injury and inhibit abnormal proliferation, but its effect on PAH remains unknown. Our preliminary results showed that PI3K/Akt/HIF-1α, ERK1/2 MAPK and TGF-β1/Smads pathways were involved in hypoxia response and transdifferentiation of endothelial cells. Baicalin inhibited the transdifferentiation of PAECs, but its mechanism was unclear. We hypothesized that baicalin might alleviate hypoxia-induced transdifferentiation of PAECs via inhibiting the above three signaling pathways. This project is about to establish the hypoxia culture model of PAECs and rat model with hypoxia PAH, so as to determine the role of baicalin in PAEC proliferation, apoptosis and transdifferentiation under the hypoxia condition; to observe the regulation of baicalin in pulmonary arterial pressure, vascular remodeling, muscularization of non-muscular pulmonary arterioles, and the related gene expression; and to investigate the molecular mechanism and therapeutic targets of baicalin in interfering hypoxia-induced PAEC response, proliferation and transdifferentiation. Therefore, the results will unravel the role and mechnism of baicalin in PAEC transdifferentiation evoked by hypoxia, which provides a candidate drug for prevention and treatment of hypoxia PAH and also helps to elucidate the pathogenesis of PAH.

肺动脉高压（PAH）至今仍无理想治疗手段，其发生与肺动脉内皮细胞转分化密切相关。黄芩苷可保护内皮损伤和抑制细胞异常增殖，但对PAH作用尚不清楚。我们的预实验表明PI3K/Akt/HIF-1α、ERK1/2 MAPK和TGF-β1/Smads信号通路参与内皮细胞缺氧应激和转分化，黄芩苷抑制肺动脉内皮细胞转分化，但作用机制未明。我们推测黄芩苷可能通过抑制上述3条信号通路，减轻缺氧诱导的肺动脉内皮细胞转分化。本项目拟建立人肺动脉内皮细胞缺氧培养和缺氧性PAH大鼠模型，证实黄芩苷对缺氧条件下肺动脉内皮细胞增殖、凋亡和转分化的作用，观察黄芩苷调节肺动脉压力、血管重构、无肌细动脉肌化及其相关基因表达，探讨黄芩苷干预肺动脉内皮细胞缺氧应激、增殖调控和转分化的分子机制及作用靶点；从而阐明黄芩苷对缺氧诱导肺动脉内皮细胞转分化的作用及其机制，为防治缺氧性PAH提供候选药物，也有助于阐明PAH发病机制。

肺动脉高压（PAH）至今仍无理想治疗手段，其发生发展与肺动脉内皮细胞（PAECs）转分化平滑肌样细胞密切相关。低氧引起的血管内皮损伤和功能障碍被认为是PAH的起始环节，也是肺血管重构的主要病理学基础，而筛选合适的药物保护肺血管内皮细胞功能，并阻抑动脉肌化进展，被认为是预防和治疗肺动脉高压的一种新策略。.本项目通过体内外实验研究黄芩苷对缺氧条件下PAECs增殖、凋亡和转分化的药理效应，并探讨其分子机制和作用靶点，同时利用大鼠PAH模型研究黄芩苷调节肺动脉平均压和血管重构及其相关基因表达水平，从而为防治PAH提供候选药物和重要靶点。.结果发现：1. PAH发生过程中，肺动脉血管壁增厚，面积变大，无肌细动脉肌化程度增加，黄芩苷能显著降低肺动脉平均压，降低血管重构，抑制相关信号分子的表达；2. 低氧和TGF-β1均可促进部分肺动脉内皮细胞转分化为平滑肌样细胞，转分化率分别为19%和6%，而当低氧+TGF-β1联合处理可提高PAECs转分化率至近100%，成功构建PAECs转分化细胞模型；3. 使用梯度浓度的黄芩苷、PI3K通路抑制剂LY294002和MAPK通路抑制剂PD98059干预PAECs转分化过程后，显示黄芩苷、LY294002、PD98059均不能明显抑制α-SMA表达，但对OPN表达有抑制作用；4. 基因表达谱芯片检测表明细胞增殖、分化、迁移等相关信号通路表达水平上调，在分子水平上证实本项目的PAECs低氧转分化模型成功构建；5. 黄芩苷通过新靶点AhR调控PAECs转分化平滑肌样细胞和平滑肌细胞（PASMCs）增殖过程，且与PI3K和MAPK通路密切相关。.本项目首次发现和证实，低氧+TGF-β1联合处理极大提高PAECs转化率，黄芩苷对PAH、血管重构、PAECs增殖和转分化及PASMCs生长具有显著干预效应，而PI3K、MAPK和AhR通路则在其机制中发挥重要作用。