1-磷酸鞘氨醇通过提高心脏微血管密度缓解压力负荷诱导的小鼠心力衰竭

Sphingosine-1-phosphate alleviates pressure overload-induced heart failure via increasing cardiac microvascular density

目的:探究1-磷酸鞘氨醇(sphingosine-1-phosphate, S1P)通过调节心脏微血管密度对压力负荷诱导的小鼠心力衰竭的作用及相关机制。方法:将8周龄的雄性C57BL/6小鼠随机分为4组:假手术(sham)组、sham+2-乙酰基-5-四羟基丁基咪唑(2-acetyl-5-tetrahydroxybutyl imidazole, THI;S1P裂解酶抑制剂)组、主动脉弓缩窄术(transverse aortic constriction, TAC)组和TAC+THI组。TAC手术后1周给予THI灌胃处理,实验终点检测各组小鼠血浆和心脏匀浆组织中S1P水平;心脏超声和Millar导管检测心功能;HE染色检测各组小鼠心脏肥大程度,Masson染色观察各组小鼠心脏间质和管周纤维化程度,CD31和麦胚凝集素免疫荧光染色观察各组小鼠心肌细胞横截面积和心脏微血管密度;RT-qPCR检测心房钠尿肽(atrial natriuretic peptide, ANP)、脑钠肽(brain natriuretic peptide, BNP)、I型胶原蛋白(collagen type I)、Ⅲ型胶原蛋白(collagen type Ⅲ)、CD31、血管性血友病因子(von Willebrand factor, vWF)和血管生成素1(angiopoietin 1, Ang1)的mRNA表达水平;Western blot检测各组小鼠心脏组织中血管内皮生长因子(vascular endothelial growth factor, VEGF)、VEGF受体(VEGF receptor, VEGFR)、磷酸化VEGFR、蛋白激酶B(protein kinase B, PKB/Akt)和磷酸化Akt的蛋白水平。结果:TAC小鼠体内S1P水平明显降低,给予THI可显著升高小鼠血浆和心脏匀浆组织中S1P水平。S1P能显著改善心衰小鼠心功能,减轻心肌肥大和纤维化表型,抑制ANP、BNP、collagen type I和collagen type Ⅲ的表达,上调血管内皮标志物CD31、Ang1和vWF的表达,激活VEGF-VEGFR-Akt信号通路,促进心脏微血管生成。结论:S1P通过VEGF-VEGFR-Akt信号通路提高心衰小鼠心脏微血管密度,从而缓解压力负荷诱导的心力衰竭。

AIM: To investigate the effect of sphingosine-1-phosphate(S1P) on pressure overload-induced heart failure in mice, and to explore its mechanism. METHODS: Eight-week-old male C57BL/6 mice were randomly divided into 4 groups: sham group, sham+2-acetyl-5-tetrahydroxybutyl imidazole(THI;an S1P lyase inhibitor) group, transverse aortic constriction(TAC) group, and TAC+THI group. The THI was administered by gavage one week after TAC surgery. The S1P level in the plasma and heart were measured by ELISA. Cardiac function of mice was detected by echocardiography and Millar catheter. Cardiac hypertrophy was observed by HE staining. Immunofluorescence staining of CD31 and wheat germ agglutinin was used to indicate the cross-sectional area of cardiomyocytes and cardiac microvascular density. Cardiac fibrosis was evaluated by Masson staining. The mRNA expression levels of atrial natriuretic peptide(ANP), brain natriuretic peptide(BNP), collagen type I, collagen type Ⅲ, CD31, angiopoietin 1(Ang1) and von Willebrand factor(vWF) were detected by RT-qPCR. The protein levels of vascular endothelial growth factor(VEGF), VEGF receptor(VEGFR), phosphorylated VEGFR, protein kinase B(PKB/Akt) and phosphorylated Akt were determined by Western blot. RESULTS: The ELISA results showed that plasma and heart S1P levels were decresed in TAC mice, while THI increased S1P levels in plasma and heart. Treatment with THI improved cardiac function of mice with heart failure.Compared with TAC group, THI increased cardiac microvascular density, while the cross-sectional area of cardiomyocytes was reduced. Masson staining revealed that S1P attenuated myocardial collagen deposition in TAC mice. The RT-qPCR results showed that S1P inhibited the expression of ANP, BNP, collagen type I and collagen type Ⅲ, but up-regulated the expression of vascular endothelial makers CD31, Ang1 and vWF. Western blot results indicated that S1P activated VEGFVEGFR-Akt signaling pathway. CONCLUSION: The S1P increases cardiac microvascular density via activation of VEGF-VEGFR-Akt signaling pathway, thus alleviating pressure overload-induced heart failure in mice.