重组高密度脂蛋白调控心肌自噬改善心功能的机制研究

HDL is a independent protective factor of cardiovascular disease. The mechanism for this have been attributed to reverse cholesterol transport. However, HDL also have potential anti-inflammatory, anti-oxidant and anti-apoptosis properties. Recent studies revealed that HDL serves as a carrier of biologically active compounds termed sphingosine-1-phosphate (S1P). The mechanism of cardioprotection by S1P is suggested: S1P binds to its membrane receptors and the complex activates protein G. Activated protein G activates PI3K which in turn activates pro-survival Akt kinase. PI3K/Akt signalling pathway had been confirmed playing an important role in autophagy and it can inhibite autophagy through downregulating the expression of autophagy-related genes (Atgs). Studies suggest that autophay is activated and may be maladaptive in the load-induced heart failure. Autophagy is an evolutionarily conserved catabolic pathway of lysosome-dependent turnover of damaged proteins and organelles and prolonged activation of autophagy pathways can result in cell death. However, there is on report about S1P regulate autophay to improve heart function via PI3K/Akt. The present study, cultured neonatal rat cardiomyocytes and adult rats were performed to prepared load-induced heart failure in vitro and in vivo, and were interfered with reconstituted HDL (rHDL). The cardiomyocyte vitality was methered with MTT method, the cells were stained with MDC, and flow cytometry was performed to identify the autophagy of cardiaomyocytes induced by load-induced heart failure, and RT-PCR and western-blot were performed to detect the mRNA and protein level of Atgs. Furthermore, it is observed whether PI3K/Akt is involved in the signal transduction of S1P anti-autophagy effect. These will help us to demonstrate rHDL can improve load-induced heart failure throug inhibited cardiomyocyte autophagy and to study the metabolisim of inhibiting autophagy via PI3K/Akt signal transduction pathway. Meanwhile, the application of rHDL will provide new theory and method for improving load-induced heart failure.

HDL是独立的心血管疾病保护因素，其生物活性成分S1P能够激活PI3K/Akt信号转导通路发挥心脏保护作用。PI3K/Akt信号通路是调控自噬的经典途径，其激活能下调自噬基因表达而抑制自噬的发生。随着压力负荷持续，心肌细胞过度自噬，使心功能进一步恶化。目前尚未见有关S1P通过激活PI3K/Akt信号转导通路抑制心肌细胞自噬保护心功能的研究报道。本研究应用包含S1P成分的重组HDL干预压力负荷心力衰竭（HF），通过体内及体外实验，测定左室收缩舒张功能、心肌细胞自噬率等指标，观察重组HDL是否能够抑制压力负荷HF诱导的心肌细胞自噬，从而改善心功能；并运用RT-PCR、Western blot等方法检测重组HDL对心肌细胞自噬基因表达的影响，为进一步深入探讨PI3K/Akt信号转导通路在重组HDL调控心肌细胞自噬中的分子机制奠定基础，为HDL心肌保护作用的机制提供新的理论依据，为心力衰竭的治疗提供新的视角。

HDL是独立的心血管疾病保护因素，业已发现其生物活性成分S1P具有心脏保护作用。本研究应用包含S1P成分的重组HDL干预压力负荷心力衰竭（HF），通过体内及体外实验，测定左室收缩舒张功能、心肌细胞自噬率等指标，观察重组HDL是否能够抑制压力负荷HF诱导的心肌细胞自噬，从而改善心功能；并运用Western blot等方法检测重组HDL对心肌细胞自噬相关蛋白表达的影响。结果表明：压力负荷小鼠心衰模型建立成功后，继续应用重组HDL干预4周，干预组小鼠心脏EF值明显高于未干预组（41.2±2.8% vs 32.5±1.4%，P< 0.05），心肌细胞的自噬率低于未干预组，干预组心肌组织的Agt5、Beclin-1、LC3-Ⅱ、LC3-Ⅰ蛋白水平的表达下降。本研究为进一步深入探讨PI3K/Akt信号转导通路在重组HDL调控心肌细胞自噬中的分子机制奠定基础，为HDL心肌保护作用的机制提供新的理论依据，为心力衰竭的治疗提供新的视角。