内质网应激在肺动脉高压引起的右心肥厚与衰竭中的作用及分子机制

Pulmonary arterial hypertension (PAH) is a severe disease characterized by an progressive increase in pulmonary vascular resistance and ultimately right ventricular hypertrophy and failure with limited therapeutic options and a dismal prognosis.It has become a serious public health problem. Right ventricular hypertrophy and failure are strong independent predictors of mortality and poor quality of life in patients with PAH. Prevention of right ventricular hypertrophy and failure for treatment of PAH has importantly clinical significance. So far,the mechanism of right ventricular hypertrophy is not clear. A large number of studies have demonstrated that endoplasmic reticulum stress (ERS) plays an important role in the development of left ventricular hypertrophy and failure. Thus, therapeutic interventions that inhibition of ERS will be promising strategies to prevent and treat left ventricular hypertrophy and failure. But the role and mechanism of ERS during the occurrence and development of right ventricular hypertrophy and failure caused by PAH is still not clear. Observation in preliminary experiments showed that the ERS related molecules GRP78 and CHOP expressed in PAH hypertrophic right ventricle organization. Upon on domestic and international researches, we hypothesized that ERS and its mediated apoptosis is a early critical determinant of right ventricular hypertrophy and failure in PAH. To address this hypothesis, we performed different animal and cell model and applied molecular biology, small interfering RNA and other technologies to prove the impact of ERS and its mediated apoptosis pathway on the development of right ventricular hypertrophy and failure.The findings are expected to further deepen the understanding of the molecular mechanisms of the development of right ventricular hypertrophy and failure in PAH, and make a breakthrough for clinical therapy of PAH, and provide a useful target for ideal therapeutic drug.

肺动脉高压（PAH）治疗棘手、预后极差，已成为严重危害社会公众的卫生问题。右心室肥厚与衰竭是PAH患者生活质量低下和预后不良的决定因素。防治右心室肥厚与衰竭对治疗PAH治疗具有十分重要的临床意义。迄今为止，右心肥厚的机制尚不明确。大量研究表明内质网应激（ERS）是影响左心室心肌肥厚、衰竭发生发展的重要因素，抑制ERS可防治左心肥厚、衰竭。但有关ERS在PAH及其导致的右心肥厚、衰竭发生发展的作用和机制尚不明确。预实验中观察到ERS相关分子GRP78和CHOP出现在PAH大鼠肥厚的右心室心肌组织中。结合国内外相关研究，我们推测，ERS 及其介导的细胞凋亡是PAH右心肥厚、衰竭发生发展的早期决定因素。为证明这种假说，本实验应用分子生物学、SiRNA等技术，从整体和细胞两个层次，观察ERS及其介导的细胞凋亡通路对右心肥厚与衰竭的影响。预期研究结果将进一步深化对PAH右心肥厚、衰竭分子机制的认识。

肺动脉高压（PAH）治疗棘手、预后极差，已成为严重危害社会公众的卫生问题。右心室肥厚与衰竭是PAH 患者生活质量低下和预后不良的决定因素。防治右心室肥厚与衰竭对治疗PAH 治疗具有十分重要的临床意义。迄今为止，右心衰竭的机制尚不明确。目前已有研究表明ERS参与PAH的发生发展，右心肥厚、衰竭与PAH密切相关，但有关ERS在PAH导致的右心肥厚、衰竭发生发展的作用和机制尚不明确。本研究探讨了ERS在PAH诱导的右心功能障碍中的作用以及抑制ERS能否对右心功能障碍起保护作用。研究结果：① 构建野百合碱诱导的PAH大鼠右心室肥厚衰竭模型、肺动脉缩窄诱导的右心室肥厚模型、内质网应激诱导原代培养心肌细胞凋亡的模型；②野百合碱（MCT）注射后3天，大鼠右心室心肌ERS分子伴侣GRP78就明显表达升高（1.5±0.06倍），并且一直持续28天，提示ERS在PAH形成之前就出现在大鼠右心室心肌，并且参与右心室心肌肥厚、功能障碍的发生发展；③ MCT注射后，ERS内质网膜上的三种感受器： IRE1、ATF 6、PERK)表达逐渐升高，在两周升高最为显著（p < 0.05），达到高峰，提示发生ERS过度。④ERS相关凋亡分子CHOP在MCT注射后3、7天表达很少，但到了14天时表达明显升高，相应的，TUNEL提示右心室心肌细胞凋亡增加，提示过度的ERS导致右心室心肌细胞凋亡；⑤ 肺动脉缩窄诱导的右心室肥厚模型，GRP78表达逐渐升高， ATF6、IRE1、PERK表达明显升高（p <0.05），但CHOP表达无明显明显升高（p >0.05）。⑥细胞学研究进一步证实炎症和缺氧可以诱导心肌细胞发生ERS，随着炎症和缺氧程度加重或持续时间延长，ERS反应程度增加，CHOP表达明显增高，心肌细胞凋亡明显；⑦探讨其保护机制，从细胞及整体动物水平证实，ERS抑制剂4-苯基丁酸（4-phenylbutyric acid，PBA)）是通过抑制PERK-eIF2α-ATF4-CHOP通路减轻了内质网应激，调节细胞Bcl-2/Bax比例的表达，从而减轻了心肌细胞凋亡，改善了PAH大鼠右心室功能障碍、衰竭的发生发展。结论：早期适度ERS促进心肌细胞代偿性肥厚，起保护作用。持续或过度ERS促进心肌细胞凋亡和右心室心肌肥厚、功能障碍。应用PBA抑制ERS可能为预防PAH患者右心室衰竭提供了一种合适的治疗途径。