花旗松素在小鼠心肌肥厚及纤维化中的作用及机制研究

Effect and mechanism of taxifolin on cardiac hypertrophy and fibrosis in mice

目的:探讨花旗松素(taxifolin,TXL)在压力负荷诱导的小鼠心肌肥厚及纤维化中的作用及机制。方法:通过主动脉缩窄术(AB)构建心肌肥厚及纤维化小鼠模型,采用随机数表法,将30只雄性C57/B6小鼠(6~8周)随机分为假手术组、AB组及AB+TXL组,每组10只。AB+TXL组小鼠在AB术后第2天给予TXL(20 mg/kg)灌胃处理,共8周。超声心动图检测小鼠心脏功能,HE染色及PSR染色评估小鼠心脏组织肥厚及纤维化情况;实时聚合酶链反应(qRT-PCR)检测心肌组织ANP、Ctgf及白细胞介素-6(IL-6)的mRNA表达水平;免疫组织化学染色标记CD45及CD68评估心肌组织白细胞和巨噬细胞的浸润情况;Western blot法检测心肌组织中磷酸化的STAT3(p-STAT3)及总STAT3(t-STAT3)的蛋白表达水平。结果:AB术后8周,与假手术组相比,AB组小鼠左室射血分数(LVEF)和左室短轴缩短率(LVFS)明显降低,左室收缩末期内径(LVESD)和左室舒张末期内径(LVEDD)明显升高,心肌细胞横截面积及心脏质量/体质量明显增加,心肌组织胶原沉积及Ctgf mRNA表达水平明显升高,心肌组织中CD45阳性白细胞和CD68阳性巨噬细胞浸润及IL-6 mRNA表达水平明显增加(P均<0.05);与AB组相比,AB+TXL组小鼠心功能明显改善,心肌细胞横截面积及心脏质量/体质量明显降低,心肌组织胶原沉积及Ctgf mRNA表达水平明显受抑,心肌组织中CD45阳性白细胞和CD68阳性巨噬细胞浸润及IL-6 mRNA表达水平明显降低(P均<0.05)。Western blot结果显示,TXL能够明显抑制AB诱导的小鼠心肌组织STAT3的磷酸化(P<0.05)。结论:花旗松素可通过调节STAT3介导的炎性反应,减轻压力负荷诱导的小鼠心肌肥厚及心肌纤维化。

Objective:To investigate the effect and mechanism of taxifolin(TXL)on cardiac hypertrophy and fibrosis induced by pressure overload in mice.Methods:Aortic banding(AB)was used to construct a model of cardiac hypertrophy and fibrosis in mice.Using a random number table,30 male C57/B6 mice(6-8 weeks old)were randomly divided into sham-operated group,AB group and AB+TXL group,and each group consisted of 10 mice.The mice in AB+TXL group were given TXL(20 mg/kg)by gavage for 8 weeks from the second day after aortic constriction surgery.Echocardiography was used to detect cardiac function in each group.HE staining and PSR staining were used to assess cardiac hypertrophy and fibrosis.The mRNA expression level of atrial natriuretic peptide(ANP),connective tissue growth factor(CTGF)and interleukin-6(IL-6)in cardiac tissue were detected by quantitative real-time PCR(qRT-PCR).The expression of CD45 and CD68 in the cardiac tissue were detected by immunohistochemical staining to evaluate the level of leukocyte and macrophage infiltration.Western blot was used to detect the protein expression levels of phosphorylated STAT3(p-STAT3)and total STAT3(t-STAT3).Results:Eight weeks after surgery,compared with the sham-operated group,in the AB group the left ventricular ejection fraction(LVEF)and left ventricular fractional shortening(LVFS)were lower,the left ventricular end-systolic diameter(LVESD),left ventricular end-diastolic diameter(LVEDD),the ratio of heart weight/body weight and cross-sectional area were larger,with higher level of collagen deposition and expression of CTGF mRNA,IL-6 mRNA as well as CD45 positive leukocytes and CD68 positive macrophages infiltration(all P<0.05).Compared with the AB group,the ratio of heart weight/body weight and cross-sectional area were smaller,and the level of collagen deposition,CD45 positive leukocytes and CD68 positive macrophages infiltration,as well as expression level of CTGF mRNA and IL-6 mRNA were lower in the AB+TXL group(all P<0.05).Western blot results showed that TXL could significantly inhibit the phosphorylation of STAT3 induced by AB in cardiac tissue of mice(P<0.05).Conclusions:TXL can reduce pressure overload-induced cardiac hypertrophy and fibrosis in mice by regulating STAT3-mediated inflammation.