甜菜碱对肝硬化大鼠肝脏巨噬细胞极化的影响

Intervention effects of betaine on macrophages polarization during development of liver cirrhosis in rats

目的:探讨甜菜碱干预对复合致病因素诱导肝硬化大鼠肝脏巨噬细胞极化的影响,并初步探讨其发挥作用可能的机制。方法:48只雄性SD大鼠随机分为空白对照组、甜菜碱干预对照组、肝硬化模型组和肝硬化模型甜菜碱干预组。各组动物分别于造模第6周末和8周末处死取材。肝组织切片行Masson染色;Elisa法检测大鼠血浆中ALT、内毒素、同型半胱氨酸(Hcy)的水平和肝组织匀浆中TNF-α、IL-6、诱导型一氧化氮合酶(iNOS)、精氨酸酶-1(Arg-1)的水平;实时荧光定量PCR法检测肝组织中葡萄糖调节蛋白78(Grp78)、CD_(86)、CD_(206)和转化生长因子-β(TGF-β_1)的信使核糖核酸(mRNA)表达。结果:与相应的空白对照组相比,肝硬化模型组动物血浆中ALT、内毒素、Hcy水平和肝组织中Grp78的mRNA表达随病程进展逐渐显著升高(P<0.05);肝组织中TNF-α、IL-6、iNOS水平和CD_(86)的mRNA表达均显著升高(P<0.05),且其6周水平高于8周;而肝组织中Arg-1水平和CD_(206)、TGF-β_1的mRNA表达在6周至8周逐渐显著升高(P<0.05)。与相应的肝硬化模型组相比,肝硬化模型甜菜碱干预组动物血浆中ALT、内毒素、Hcy水平和肝组织中Grp78的mRNA表达均显著降低(P<0.05);肝组织中TNF-α、IL-6水平在6周显著降低(P<0.05),8周变化不明显;肝组织中iNOS、Arg-1水平和肝组织中CD_(86)、CD_(206)、TGF-β_1的mRNA表达均显著降低(P<0.05)。相关性分析结果显示:大鼠血浆中内毒素水平与肝组织中Grp78的mRNA表达显著相关(P<0.01),血浆中内毒素水平和肝组织中Grp78的mRNA表达分别与肝组织中CD_(86)、CD_(206)的mRNA表达显著相关(P<0.01)。结论:甜菜碱可能通过降低血浆内毒素水平,拮抗肝脏内质网应激反应,调节巨噬细胞的极化状态等途径,发挥保护肝脏的作用。

AIM： To explore the effect and mechanism of betaine on macrophage polarization in the development of liver cirrhosis in rats. METHODS： Forty-eight male SD rats were randomly divided into normal control group（ N）,normal control plus betaine-treated group（ NB）, liver cirrhosis group（ M）, liver cirrhosis plus betaine-treated group（ MB）. At the 6th and 8th weeks,liver cirrhosis in rats was induced by multiple pathogenic factors. Betaine was given in rats of NB and MB groups（ 1g · kg^-1· d^-1,ig）. Levels of alanine transferase（ ALT）, endotoxin, homocysteine（ Hcy） in the plasma,tumor necrosis factor-α（ TNF-α）,interleukin-6（ IL-6）,inducible nitric oxide synthase（ iNOS）,arginase-1（ Arg-1） in the liver tissues were detected by Elisa. Histopathological change of the liver was observed under microscope with the staining of Masson. Expressions of glucoseregulated protein 78（ Grp78）,CD86,CD206 and transforming growth factor-β1（ TGF-β1） at mRNA levels in the liver tissues were detected by method of real-time fluorescence quantitative PCR. RESULTS： Compared with the corresponding normal control group,levels of ALT,endotoxin,Hcy in the plasma and Grp78 mRNA in the liver tissues of liver cirrhosis group were significantly increased（ P〈0. 05）. Levels of TNF-α,IL-6,iNOS and CD（86） mRNA in the liver tissues were significantly increased（ P〈0. 05）（ they increased at the 6th week while decreased reversely at the 8th week）. Levels of Arg-1 and mRNA expressions of CD（206）,TGF-β1in the liver tissues were significantly increased from the 6th to 8th week（ P〈0. 05）. Compared with the corresponding liver cirrhosis group,levels of ALT,endotoxin,Hcy in the plasma and the mRNA expression of Grp78 in the liver tissues of liver cirrhosis plus betaine-treated group were significantly decreased（ P〈0. 05）. Levels of TNF-α,IL-6 in the liver tissues were significantly decreased at the 6th week（ P〈0. 05）,and no significant difference at the 8th week was observed. Levels of iNOS,Arg-1and mRNA expressions of CD（86）,CD（206）,TGF-β1in the liver tissues were further significantly decreased（ P〈0. 05）. The level of endotoxin in the plasma was correlated with the mRNA expression of Grp78 mRNA in the liver tissues（ P〈0. 01）. Both endotoxin in the plasma and Grp78 mRNA in the liver tissues were correlated with the mRNA expressions of CD（86）,CD（206） in the liver tissues respectively（ P〈0. 01）. CONCLUSION： Betaine can protect the liver by decreasing the plasma endotoxin level,inhibiting the endoplasmic reticulum stress and adjusting the polarization state of the macrophages.