郑州市第七人民医院心血管内科,郑州 450000
R-33
Department of Cardiology, Zhengzhou Seventh People’s Hospital, Zhengzhou 450000, China
目的 探讨髓样分化蛋白 1(MD1)的缺失通过激活 Toll 样受体 4(TLR4) / 髓样分化因子(MyD88) 信号通路增加肥胖小鼠室性心律失常的易感性。 方法 对 MD1 基因敲出小鼠 16 只和雄性 WT 小鼠 16 只进行分组,分别为 WT 正常组、MD1-ko-正常组、WT 高脂组、MD1-ko-高脂组。 WT 高脂组和 MD1-ko-高脂组小鼠喂养 20 周高脂肪食物(含 60%的脂肪),WT 正常组和 MD1-ko- 正常组正常饲料(含 10%的脂肪) 喂养。测量小鼠的体重 (BW)、血糖值、总胆固醇、甘油三酯和低密度脂蛋白胆固醇水平、HW/ BW 的比值。通过心电图和超声心动图测量 RR 间距、PR 间距、QRS 持续时间、QTc 间期、LVEDd、LVEDs、LVFS 和 LVEF。 采用 Western blot 检测对分析 TLR4、 MyD88、P-CAMKII、CollagenI、CollagenIII 和 TGF-β1 蛋白水平。通过 HE 染色和 PSR 染色观察小鼠心肌肥大和纤维化。 结果 MD1-ko-高脂组中的体指数、血糖值、总胆固醇、甘油三酯、低密度脂蛋白胆固醇、QTc 间期、LVEDd、 LVEDs、LVFS、LVEF 明显高于 WT 高脂组(均 P< 0. 05);MD1-ko-高脂组的动作点位时程(APD20、APD50、APD90) 显著高于 WT 高脂组(P< 0. 05);MD1-ko-高脂组 APD 交替阈值显著高于 WT 高脂组(P< 0. 05);MD1-ko-高脂组心律失常比例显著高于 WT 高脂组(P< 0. 05);MD1-ko-高脂组中 TLR4、MyD88 和 P-CAMKII 蛋白的表达明显高于 WT 高脂组(均 P< 0. 05);MD1-ko- 高脂组 HW/ BW 比值(7. 59±0. 78) 明显高于 WT 高脂组( 6. 07± 0. 58) (P< 0. 05)。 MD1-ko-高脂组小鼠心肌细胞横截面积(381. 23±35. 76)μm2 明显高于 WT 高脂组(190. 15±25. 23)μm2(P< 0. 05); MD1-ko-高脂组的 CollagenI、CollagenIII 和 TGF-β1 的蛋白明显高于 WT 高脂组(P< 0. 05)。 结论 MD1 缺乏增加了 高脂饮食诱导的心律失常的易感性,主要原因是由于 TLR4 / MyD88 信号通路的激活增强,导致左心室的肥厚和纤维化,增加了 TLR4 / MyD88 信号通路相关蛋白的表达。
Objective To investigate effects of MD1 deficiency on the susceptibility of obese mice to ventricular arrhythmias and the mechanism involved. Methods Sixteen MD1-knockout (KO) mice and 16 male wild type (WT) mice were divided into WT normal group, MD1-ko- normal group, WT high fat group and MD1-ko- high fat group. The high fat groups were fed a high-fat diet (fat energy accounted for 60%) for 20 weeks, and the normal groups were fed a normal diet (fat energy accounted for 10%). The body weight (BW), heart weight ( HW), blood glucose level, total cholesterol, triglyceride and low-density lipoprotein ( LDL) cholesterol levels, and HW/ BW ratio of the mice were measured. RR spacing, PR spacing, QRS duration, QTc interval, LVEDd, LVEDs, LVFS, and LVEF were measured by electrocardiography and echocardiography. Western blot was used to analyze TLR4, MyD88, P-CAMKII, Collagen I, Collagen III and TGF-β1 protein levels. Cardiac hypertrophy and fibrosis were observed in mice by HE staining and PSR staining. Results The body index, blood glucose, total cholesterol, triglyceride, LDL cholesterol, QTc interval, LVEDd, LVEDs, LVFS, and LVEF were significantly higher in the MD1-ko- high fat group than in the WT high fat group (P < 0. 05). Furthermore, the action potential duration ( APD20, APD50, APD90) of the MD1-ko- high fat group was significantly higher than that of the WT high fat group (P <0. 05), and he APD alternating threshold of the MD1-ko- high fat group was significantly higher than that of the WT high fat group (P< 0. 05). The arrhythmia ratio of the MD1-ko- high fat group was significantly higher than that of the WT high fat group (P < 0. 05). The expression of TLR4, MyD88, and P- CAMKII in the MD1-ko- high fat group was significantly higher than that in the WT high fat group (P < 0. 05). The HW/ BW ratio in the MD1-ko- high fat group (7. 59 ± 0. 78) was significantly higher than that in the WT high fat group (6. 07 ± 0. 58; P < 0. 05). The Gross hearts of the MD1-ko- high fat group (381. 23 ± 35. 76) μm2was significantly higher than that of the WT high fat group (190. 15 ± 25. 23) μm2 ; P < 0. 05). Finally, the protein expression of Collagen I, Collagen III, and TGF-β1 in the MD1-ko- high fat group was significantly higher than that in the WT high fat group (P< 0. 05). Conclusions MD1 deficiency increases the susceptibility to high-fat-diet-induced arrhythmias, mainly because of enhanced activation of the TLR4 / MyD88 signaling pathway, leading to left ventricular hypertrophy and fibrosis, which increases the expression of TLR4 / MyD88 signaling pathway-related proteins.
. MD1 的缺失通过激活 TLR4 / MyD88 信号通路增加肥胖小鼠室性心律失常的易感性[J].中国比较医学杂志,2020,30(6):76~82.
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