过度自噬介导心肌肥厚心功能不全

Excessive activation of autophagy mediates the development of cardiac dysfunction due to cardiac hypertrophy

目的研究自噬在心肌肥厚心功能不全中的作用。方法采用前期构建的心肌肥厚心功能失代偿的热休克蛋白27转基因鼠（heat shock protein transgenic mice,Hsp27 Tg）模型（4周龄、雌性）,随机分为（1）自噬抑制（WM）组：自噬抑制剂渥曼青霉素（wortmannin,WM）溶于DMSO溶剂,以1 mg/kg腹腔注射;（2）溶剂组：等体积的DMSO溶剂腹腔注射,连续3~7周龄。选取年龄、性别匹配的野生型对照鼠（wild type,WT）作为WT组。于注射WM前、后,测定心脏质量/体质量比值（heart weight/body weight,HW/BW）,以二维超声心动图测定心功能,以免疫印迹方法测定LC3-Ⅱ/LC3-Ⅰ比值和p62水平以评价自噬水平。结果 （1）与WT组相比,4周龄Hsp27 Tg鼠HW/BW显著增加,而心脏射血分数（ejection fraction,EF%）和短轴缩短率（fraction shortening,FS%）均显著下降（P〈0.01）;（2）与WT组相比,4周龄Hsp27 Tg鼠心肌组织中LC3-Ⅱ/LC3-Ⅰ比值升高,而p62水平下降（P〈0.01）;（3）与溶剂组比较,注射3周后的WM组Hsp27 Tg鼠心肌组织中LC3-Ⅱ/LC3-Ⅰ水平下降,而p62水平升高（P〈0.01）;（4）与溶剂组比较,WM注射3周Hsp27 Tg鼠的心脏EF%、FS%均显著增加（P〈0.01）。结论WM通过抑制自噬水平改善Hsp27高表达诱导的病理性心肌肥厚心功能不全,提示过度自噬介导了心肌肥厚心功能不全的进展,为进一步探究心肌肥厚失代偿阶段的发病机制提供理论基础。

Objective To investigate the role of autophagy in the progress of cardiac dysfunction due to cardiac hypertrophy. Methods The established pathological cardiac hypertrophy induced by high overexpression of Hsp27 in mice at the age of four weeks were divided into two groups：（ 1） vehicle-treated controls;（ 2） autophagy inhibition group：autophagy inhibitor Wortmannin（ WM） was injected intraperitoneally（ 1 mg / kg） for three weeks. Age- and gendermatched wild type（ WT） mice were chose as WT group. Heart weight to body weight ratio（ HW / BW） were measured.Cardiac function was evaluated by two-D echocardiography. The autophagic flux was indicated by LC3-Ⅱ / LC3-Ⅰ ratio and p62 protein degradation. Results（ 1） Compared with WT group,Hsp27 Tg mice showed an increased HW / BW ratio and declined cardiac ejection fraction（ EF%） and fraction shortening（ FS%）（ P〈0. 01）;（ 2） Compared with WT group,Hsp27 Tg mice exhibited an increased LC3-Ⅱ / LC3-I ratio and decreased p62 protein level（ P〈0. 01）;（ 3） A dministration with WM for 3 weeks in Hsp27 Tg mice decreased LC3-Ⅱ / LC3-I ratio and increased p62 protein level,compared with vehicle-treated controls（ P〈0. 01）;（ 4） Administration with WM for 3 weeks increased EF% and FS% in Hsp27 Tg mice compared with vehicle-treated controls（ P〈0. 01）. Conclusions WM improves cardiac dysfunction in mice with cardiac hypertrophy through inhibiting autophagy,which indicates the excessive activation of autophagy mediates the progress of cardiac dysfunction from cardiac hypertrophy. The data suggest that targeting of autophagy may serve as an alternative approach for the treatment of maladaptation of cardiac hypertrophy.