重组小鼠白细胞介素11致小鼠心肌纤维化的实验探究

Experimental research on cardiac fibrosis induced by recombinant mouse interleukin-11 in mice

目的:观察皮下注射重组小鼠白细胞介素11(rmIL-11)对小鼠心脏结构功能的影响并明确其促进心肌纤维化的作用。方法:将C57BL/6小鼠随机分为实验组和溶媒对照组,实验组小鼠背部皮下注射rmIL-11,100μg·kg-1·d-1,连续注射3周;而对照组同法皮下注射等量的生理盐水。实验结束后,超声心动图测定小鼠心功能参数;取心脏称重,计算心重指数(CWI);HE染色和Masson染色分别观察小鼠心肌组织病理变化及纤维化程度,并计算心肌胶原容积分数(CVF);Western blot技术检测2组小鼠心肌组织中细胞外基质组分Ⅰ型、Ⅲ型胶原及纤连蛋白等蛋白表达的变化。结果:超声心电图结果显示实验组小鼠左室射血分数和短轴缩短率均明显降低(P<0.01),而左室舒张末期内径和收缩末期内径均明显增大(P<0.05)。与对照组比较,实验组小鼠CWI明显增大(P<0.01),心肌排列紊乱,肌细胞坏死增多,且细胞间可见大量胶原纤维沉积,相应地,CVF和左室Ⅰ型、Ⅲ型胶原及纤连蛋白表达水平明显增加(P<0.05)。结论:皮下注射rmIL-11能诱导小鼠心肌纤维化发生,揭示IL-11可能是一种新的促纤维化因子。

AIM:To observe the effect of recombinant mouse interleukin-11(rmIL-11)injected subcutaneously into mice on heart structure and function and to determine its pro-fibrotic effect.METHODS:C57 BL/6 mice were randomly divided into experimental group and control group. The mice in experimental group were injected subcutaneously with recombinant mouse IL-11 at the dose of 100 μg·kg-1·d-1 for 3 consecutive weeks,while the control group were given equal volume of normal saline in the same way. After the experiment was finished,the parameters of heart function were measured by echocardiography. The heart weight was weighed and the cardiac weight index(CWI)was calculated. HE staining and Masson’s trichrome staining were performed to observe the pathological changes and the extent of myocardial fibrosis in mouse myocardia respectively,and the cardiac collagen volume fraction(CVF)was calculated. The expression levels of extracellular matrix proteins in the myocardial tissues of mice,including type Ⅰ collagen,type Ⅲ collagen and fibronectin,were determined by Western blot.RESULTS:Left ventricular ejection fraction and left ventricular fraction shortening in experimental group were obviously lower than those in control group(P<0. 01),however left ventricular enddiastolic diamension and left ventricular end systolic dimension were significantly higher than those in control group(P<0. 05). Compared with control group,the CWI was increased(P<0. 01),the myocardial arrangement was disorder,the necrosis of cardiac myocytes was increased,and excessive deposition of collagen was observed in the myocardial tissues in experimental group. Correspondingly,the CVF and protein levels of type Ⅰ collagen,type Ⅲ collagen and fibronectin in the left ventricle in experimental group were increased significantly(P<0. 05).CONCLUSION:Injection of rmIL-11 into the mice subcutaneously induces fibrogenesis in the heart,which implies that IL-11 is likely a novel pro-fibrotic factor.