肝星状细胞活化和肝脏巨噬细胞的募集是肝纤维化过程中重要环节，星状细胞分泌的TIMP-1有促肝纤维化作用。我们前期研究发现：动物体内干预TIMP-1具有的抗肝纤维化作用，与巨噬细胞向肝脏的募集减少以及CCL2分泌降低相关，但作用机制尚不明确。同时发现细胞分泌的外泌小体可以稳定传递miRNA信息，反映细胞功能状态。本课题拟首先以前期发现的与CCL2表达相关的miRNA145为切入点，明确TIMP-1通过miRNA145调控CCL2蛋白表达的分子机制。其次观察携带miRNA145的外泌小体在星状细胞之间以及星状细胞和巨噬细胞之间的胞间传递及对CCL2蛋白表达的影响。最后利用小鼠四氯化碳肝纤维化模型，探讨TIMP-1下调后的星状细胞通过外泌小体传递抑制巨噬细胞趋化信息进而发挥抗肝纤维化作用的可能性。本研究将明确TIMP-1调控CCL2的具体分子机制并为外泌小体为载体的抗肝纤维化治疗提供实验室依据。

The activation of hepatic stellate cells (HSCs) and the recruitment of hepatic macrophages to the injured liver are the central events in the progression of liver fibrosis. The tissue inhibitor of metalloproteinase-1 (TIMP-1) secreted by HSCs plays crucial role in fibrogenesis. Our previous studies found that the antifibrotic effects of a recombinant adeno-associated virus carrying small interfering RNA targeting TIMP-1 in rat liver fibrosis were associated with decreased recruitement of hepatic macrophages and less expression of C-C motif ligand 2 (CCL2) in the liver. However, the mechanisms remain unclear. Exosomes, small vesicles containing miroRNAs (miRNAs) and other nucleic acids in the form of steady state, are important in intercellular communication. Our preliminary data has also shown that the changes of miRNA in exosomes isolated from cell cultrue medium were consistent with that in the cultured cells, indicating that the information carried by exosomes reveals the cell conditions. Based on our preliminary data that miRNA145 maybe correlated with the transcription of CCL2, in the present study we will further determine the regulatory mechanism of TIMP-1 on CCL2 transcription through miRNA145. Furthermore, we will elucidate the intercellular communication by exosomes containing miRNA145 between HSCs, as well as HSCs and hepatic macrophages and expression of CCL2 in target cells. Lastly, we will investigate whether the infusion of exosomes containing miRNA145 will alter CCL2 expression in serum and liver of receptor mice and have antifibrotic effectes in carbon tetrachloride induced liver fibrosis mice model. This study may help clarify the regulating mechanism of TIMP-1 on CCL2 transcription and feasibility of exosomes as vector in antifibrotic strategy.