内毒素对实验性肝纤维化大鼠基质金属蛋白酶-2的影响

目的探讨内毒素对早期实验性肝纤维化大鼠基质金属蛋白酶-2（MMP-2）的影响及其在肝纤维形成过程中的作用机制。方法建立实验性肝纤维化大鼠模型，采用免疫组化染色法半定量测定MMP-2、α-SMA在肝纤维化过程中的时序动态表达，网状纤维法判定肝纤维化程度，同时采用ELISA法测定血浆内毒素和TNF-α的水平。结果有内毒素血症发生，不同时期（0、2、4、6周）血浆内毒素水平呈梯度增加，组间差异明显，血浆内毒素与TNF-α及肝组织MMP-2、α-SMA表达有较好的相关性。MMP-2表达的部位、时序、量的变化都与α-SMA的表达大致平行，以中央静脉周围、汇管区、纤维间隔内为明显，提示MMP-2主要由活化的肝星状细胞（HSC）合成。肝纤维化程度与α-SMA、MMP-2在肝脏的表达呈正相关。结论内毒素可能通过细胞因子TNF-α，介导肝组织MMP-2、α-SMA的表达，而后者又与肝纤维化的程度密切相关。

Effects of endotoxin on MMP-2 in the experimental liver fibrosis rats

Objective To explore the effect of endotoxin on matrix metalloproteinases-2 （MMP-2） in the experimental liver fibrosis rats, and the mechanism to form liver fibrosis. Methods An experimental CCl4 induced liver fibrosis rat model was established by intraperitoneal administration of carbon tetraehloride for 2, 4, 6 weeks. The dynamic expression of MMP-2 and α-smooth muscle aetin （α-SMA） in 2, 4, 6 weeks were semi-quantitatively determinated by immunohistoehemisty, and reticular fiber staining method was adopted to estimate the degree of liver fibrosis, meanwhile the ELISA method was used to determine the levels of plasma endotoxin and tumor necrosis factor alpha （TNF-α）. Results Endotoxemia occurred in our rat models. The plasma endotoxin levels （0, 2, 4, 6 weeks） increased significantly, which were closely related to the plasma TNF-α and the expressions of MMP-2 and α-SMA in the liver. The expression of MMP-2 was always in accordance with the α-SMA in the site of expression, time and content, especially in the central veins around, header area, and fibrous septum. MMP-2 was mainly synthetized by the activated hepatic stellate cell. There was a direct correlation among degree of liver fibrosis, MMP-2 and α-Smooth muscle actin （α-SMA） expression in liver. Conclusion Through inducing the cytokines TNF-α, the endotoxin mediates the expressions of MMP-2 and α-SMA in liver tissue, which are closely related to the degree of liver fibrosis.