替普瑞酮通过E3泛素连接酶CHIP减轻LPS引起的心肌炎症反应和心功能障碍

Teprenone alleviates LPS-induced inflammatory response and cardiac dysfunction through E3 ubiquitin ligase CHIP

目的:探究替普瑞酮又称香叶基香叶基丙酮,GGA)对脂多糖(LPS)诱导的心功能障碍的治疗作用及机制。方法:(1)取8周龄C57BL/6雄性野生型小鼠和热休克蛋白70(HSP70)羧基末端相互作用蛋白(CHIP)基因敲除小鼠,随机分为对照组、LPS组、LPS+GGA组和GGA组,每组8只。用腹腔注射LPS(25 mg/kg)的方法建立模型,于LPS刺激后1 h给予小鼠腹腔注射GGA(100 mg/kg)。利用小动物超声系统评估小鼠心脏功能;采集各组小鼠血清,检测血清肌酸激酶同工酶(CK-MB)和乳酸脱氢酶(LDH)水平;HE染色观察病理学改变;ELISA检测心脏组织中炎症因子肿瘤坏死因子α(TNF-α)和白细胞介素6(IL-6)的水平;Western blot检测各组心脏组织HSP70、CHIP、核转运蛋白α2(KPNA2)、髓过氧化物酶(MPO)、血管细胞黏附分子(VCAM)和细胞间黏附分子(ICAM)的蛋白表达以及细胞核NF-κB的水平。(2)利用小鼠心肌细胞HL-1,建立LPS刺激的离体细胞炎症模型。ELISA检测细胞上清中TNF-α和IL-6的水平;Western blot检测心肌细胞中HSP70、CHIP和KPNA2蛋白表达;免疫荧光染色观察细胞核NF-κB的表达。结果:(1)GGA有效改善LPS刺激小鼠的心脏功能,显著提高射血分数和左室短轴缩短率(P<0.01),减少血清CK-MB和LDH含量(P<0.01),减轻心肌损伤。(2)GGA显著减少LPS引起的TNF-α和IL-6炎症因子的释放(P<0.01),以及NF-κB的入核,降低心肌组织中KPNA2、MPO、VCAM和ICAM蛋白表达,增加心肌组织和细胞HSP70的水平(P<0.01)。(3)在CHIP基因敲除的心肌细胞和小鼠中,GGA不能抑制LPS引起的炎症反应,失去了改善LPS刺激小鼠心脏功能的作用。结论:GGA能够减轻LPS引起的心功能障碍,其作用机制与升高HSP70的表达,促进CHIP的活化,减少NF-κB的入核,抑制炎症因子的释放有关。CHIP的敲除使GGA丧失了减轻LPS诱导的炎症反应和心肌损伤的作用。

AIM:To explore the therapeutic effect of teprenone(geranylgeranylacetone,GGA)on lipopolysac-charide(LPS)-induced cardiac dysfunction and its mechanism.METHODS:(1)Eight-week-old male C57BL/6 wild-type mice and carboxyl terminus of heat shock protein 70(HSP70)-interacting protein(CHIP)gene knockout mice were randomly divided into control group,LPS group,LPS+GGA group and GGA group,with 8 mice in each group.The model was established by intraperitoneal injection of LPS(25 mg/kg),and 1 h after LPS stimulation,mice were given intraperito-neal injection of GGA(100 mg/kg).The technique of high-resolution ultrasonography system was used to evaluate the car-diac function of mice.The serum of mice from each group were collected to detect the levels of creatine kinase-MB(CK-MB)and lactate dehydrogenase(LDH).HE staining was performed to observe histological changes of cardiac tissues.ELISA was used to detect the levels of tumor necrosis factor-α(TNF-α)and interleukin-6(IL-6)in cardiac tissues.West-ern blot was used to detect the protein levels of HSP70,CHIP,karyopherin-α2(KPNA2),myeloperoxidase(MPO),vas-cular cell adhesion molecule(VCAM),intercellular cell adhesion molecule(ICAM),and nuclear factor-κB(NF-κB)in cardiac tissues.(2)In vitro cell inflammation model was established using mouse myocardial cells HL-1 stimulated with LPS.ELISA was used to detect the levels of TNF-αand IL-6 in cell supernatants.Western blot was used to detect the pro-tein expression levels of HSP70,CHIP,and KPNA2 in myocardial cells.Immunofluorescence staining was performed to observe the content of nuclear NF-κB.RESULTS:(1)GGA effectively improved cardiac function of LPS-stimulated mice,significantly increased ejection fraction and left ventricular fractional shortening(P<0.01),reduced serum levels of CK-MB and LDH(P<0.01),and alleviated myocardial injury.(2)GGA significantly reduced the release of TNF-αand IL-6 caused by LPS(P<0.01),as well as nuclear translocation of NF-κB,decreased the levels of KPNA2,MPO,VCAM and ICAM in cardiac tissues,and increased the levels of HSP70 in cardiac tissues and cells(P<0.01).(3)In CHIP knockout myocardial cells and mice,GGA failed to inhibit LPS-induced inflammatory response and lost its effect on im-proving cardiac function.CONCLUSION:The protective effect of GGA against LPS-caused cardiac dysfunction of mice is related to increasing expression of HSP70 and promoting CHIP activation,which inhibits the translocation of NF-κB into nucleus and suppresses inflammatory factor release.CHIP knockout abolishes the effects of GGA on reducing LPS-induced inflammatory response and myocardial injury.