心脏肥大细胞及Toll样受体4在小鼠病毒性心肌炎中的作用

目的：探讨心脏肥大细胞及Toll样受体4（TLR4）在病毒性心肌炎（VMC）发生发展中的作用。方法：48只BALB/C小鼠随机分为对照组和模型组，每组24只，以柯萨奇病毒B3腹腔注射制作VMC模型，分别于制模后7 d、14 d和28 d，两组各取8只小鼠心肌组织，行苏木精-伊红和Masson染色观察两组小鼠心肌病理改变，以甲苯胺蓝染色法和透射电镜检测两组小鼠各时间点心肌肥大细胞数目及脱颗粒情况，采用免疫组化法及RT-PCR检测小鼠心肌TLR4及其mRNA的表达，并对模型组各时间点肥大细胞数目及TLR4 mRNA的表达进行相关性分析。结果：模型组各时间点心肌病理评分均较对照组明显增高（均P<0.05）；模型组28 d时心肌胶原纤维容积分数较对照组各时间点以及模型组7 d、14 d时均明显增高（均P<0.05）。模型组肥大细胞数目明显多于对照组相应时间点（均P<0.05）；各时间点模型组心肌TLR4及其mRNA表达均高于对照组（P<0.05）。模型组各时间点心肌肥大细胞数目和TLR4 mRNA表达呈正相关（R2=0.877, P<0.05）。结论：VMC小鼠心肌肥大细胞数和TLR4的表达在各时间点均较对照组明显增加，提示肥大细胞及TLR4可能在VMC的炎症反应和纤维化过程中起重要作用。

Roles of cardiac mast cells and Toll-like receptor 4 in viral myocarditis among mice

Objective To investigate the role and significance of cardiac mast cells and Toll-like receptor 4 (TLR4) in the development and progression of viral myocarditis (VMC). Methods Forty-eight Balb/c mice were randomly divided into a control group (n=24) and a model group (n=24). Coxsackievirus B3 was intraperitoneally injected into the model group mice to establish a VMC model. In each group, cardiac tissues were collected from 8 mice at 7, 14 and 28 days after the model was established. The cardiac tissues were stained with hematoxylin and eosin as well as Masson trichrome to observe pathological changes in cardiac tissues. The number and degranulation of cardiac mast cells at each time point were measured and evaluated by toluidine blue staining and transmission electron microscopy. The mRNA and protein expression of TLR4 in cardiac tissues was measured by RT-PCR and immunohistochemistry. In the model group, the correlation between number of cardiac mast cells and mRNA expression of TLR4 at all time points was analyzed. Results The model group had significantly higher pathological scores of cardiac tissues than the control group at all time points (P<0.05). The myocardial collagen volume fraction in the model group at 28 days was significantly higher than in the control group at all time points and higher than in the model group at 7 and 14 days (P<0.05). At each time point, the model group had a significantly increased number of mast cells (P<0.05), and significantly increased mRNA and protein expression of TLR4 (P<0.05) compared with the control group. In the model group, the number of cardiac mast cells was positively correlated with the mRNA expression of TLR4 at all time points (R2=0.877, P<0.05). Conclusions Mice with VMC have significantly increased numbers of cardiac mast cells and expression of TLR4 compared with control mice at all time points, suggesting that mast cells and TLR4 may play important roles in the inflammatory response and fibrosis of VMC.