肝纤维化发生时15d-PGJ2通过MIF抑制骨髓来源的单核巨噬细胞的浸润和活化

We reported 15-deoxy-delta12, 14-Prostagandin J2, (15d-PGJ2) inhibits migration of bone marrow-derived monocyte/macrophage cells (BMM) to the injured liver during liver fibrosis. Hepatic inflammation and fibrosis were also strikingly ameliorated after 15d-PGJ2 administration (Hepatology,2012). But the underlying mechanism remains elusive. Macrophage migration inhibitory factor (MIF) as a proinflammatory cytokine may play an important role in this process. Our preliminary results indicate that the expression of MIF was significantly increased during liver fibrosis. Treatment with 15d-PGJ2 reduced the expression of MIF. Besides,MIF protein was expressed in the BMM infiltrated at the sites of fibrotic liver or in the BMM obtained from mice. Based on these findings, We hypothesize that 15d-PGJ2 reduces BMM migration to the lesion through MIF during liver fibrosis, Accordingly, hepatic inflammation and fibrosis are ameliorated. In this study, we will first investigate the effect of 15d-PGJ2 on MIF in mouse models of bile duct ligation (BDL)- or carbon tetrachloride (CCl4)-induced liver injury. In addition, we will determine the effects of 15d-PGJ2 on migration, phagocytic activity, and inflammatory cytokines generation in the BMM by changing the expression of MIF. To assess the therapeutic potential of 15d-PGJ2 in hepatic inflammation and fibrosis through regulation of MIF, we will examine the inflammation area, production of inflammatory cytokines, and deposition of collagen in liver tissue of mice injected with recombinant lentiviral vector of MIF. We will perform cell coculture and genetic EGFP-labeled mice to explore the mechanisms of 15d-PGJ2 in the inhibition of BMM and liver fibrosis. Our results will provide new insight into the antifibrogenic mechanism of 15d-PGJ2, as well as a new therapeutic target for liver fibrosis.

我们报道了小鼠肝纤维化过程中，15d-前列腺素J2 (15d-PGJ2)抑制骨髓来源的单核巨噬细胞 (BMM) 向受损肝脏的浸润和活化，从而减轻了小鼠肝脏的炎症及纤维化(Hepatology,2012)，但其具体的分子机理尚不清楚。巨噬细胞迁移抑制因子(MIF)作为炎症'瀑布'上游的促炎因子可能在其中发挥重要作用。前期实验结果表明：小鼠肝纤维化时，MIF的表达增加，且迁移至纤维化部位的BMM和体外培养的BMM均表达MIF； 当用15d-PGJ2 干预后，发现MIF的表达降低，提示：MIF可能在15d-PGJ2对BMM的作用过程中发挥重要功能。故提出假说：小鼠肝纤维化时，15d-PGJ2通过下调MIF，抑制BMM向纤维化部位浸润，从而缓解肝脏的炎症和纤维化。本课题拟应用骨髓细胞被EGFP标记的嵌合体小鼠和原代培养的BMM为研究对象，验证假说。从新的角度探讨15d-PGJ2抗纤维化的分子机制。

背景：.15d-PGJ2 抑制骨髓来源的单核巨噬细胞向受损肝脏浸润，从而减轻了小鼠肝脏的炎症，但具体的分子机制尚不清楚。前期试验提示：15d-PGJ2可能通过调控MIF，抑制BMM浸润至受损的肝脏，这很可能是15d-PGJ2发挥抗炎和抗纤维化作用的主要机制。.结果：.1.在小鼠急性肝损伤模型中，MIF主要表达在肝脏实质细胞中，且15d-PGJ2 能够下调MIF表达。MIF蛋白在损伤后表达水平升高，而15d-PGJ2 治疗组小鼠肝组织样品中MIF表达和分泌发生下调。.2. 小鼠急性肝脏损伤模型中,15d-PGJ2 能够抑制MCP-1，TNFα，IL-1β，IL-6，IL-12炎症因子表达, 并且可以减轻肝脏炎症反应。15d-PGJ2 阻止骨髓来源的单核巨噬细胞侵袭至受损伤肝脏。 .3.原代培养的肝细胞和AL-12细胞能够表达和分泌MIF，15d-PGJ2 阻止了LPS刺激引起的MIF mRNA和蛋白表达水平下调。.4. 在原代培养的肝细胞和AL-12细胞中发现15d-PGJ2 和MIF抑制了MCP1，TNFα，IL-1β，IL-6，和IL-12等炎性因子的表达，抑制了骨髓来源的单核巨噬细胞的迁移和活化。.5. 15d-PGJ2依赖PPARγ激活途径调控MIF的表达，而不依赖ROS形成途径调控这一事件。.科学意义：.本研究首次探讨了MIF参与15d-PGJ2抑制骨髓来源单核巨噬细胞迁移至收损伤肝脏的过程，有助于阐明15d-PGJ2 抑制肝脏炎症和纤维化的分子机制，为临床提供以MIF作为药物靶点治疗肝脏疾病的新思路。