Seki Ekihiro, de Minicis Samuele, Inokuchi Sayaka, Taura Kojiro, Miyai Katsumi, van Rooijen Nico, Schwabe Robert F, Brenner David A
Department of Medicine, University of California, San Diego, School of Medicine, La Jolla, CA 92093-0702, USA.
Hepatology. 2009 Jul;50(1):185-97. doi: 10.1002/hep.22952.
Chemokines and chemokine receptors contribute to the migration of hepatic stellate cells (HSCs) and Kupffer cells, two key cell types in fibrogenesis. Here, we investigate the role of CCR2, the receptor for monocyte chemoattractant protein (MCP)-1, MCP-2, and MCP-3, in hepatic fibrosis. Hepatic CCR2, MCP-1, MCP-2, and MCP-3 messenger RNA expression was increased after bile duct ligation (BDL). Both Kupffer cells and HSCs, but not hepatocytes, expressed CCR2. BDL- and CCl(4)-induced fibrosis was markedly reduced in CCR2(-/-) mice as assessed through collagen deposition, alpha-smooth muscle actin expression, and hepatic hydroxyproline content. We generated CCR2 chimeric mice by the combination of clodronate, irradiation, and bone marrow (BM) transplantation allowing full reconstitution of Kupffer cells, but not HSCs, with BM cells. Chimeric mice containing wild-type BM displayed increased macrophage recruitment, whereas chimeric mice containing CCR2(-/-) BM showed less macrophage recruitment at 5 days after BDL. Although CCR2 expressed in the BM enhanced macrophage recruitment in early phases of injury, CCR2 expression on resident liver cells including HSCs, but not on the BM, was required for fibrogenic responses in chronic fibrosis models. In vitro experiments demonstrated that HSCs deficient in CCR2(-/-) or its downstream mediator p47phox(-/-) did not display extracellular signal-regulated kinase and AKT phosphorylation, chemotaxis, or reactive oxygen species production in response to MCP-1, MCP-2, and MCP-3.
Our results indicate that CCR2 promotes HSC chemotaxis and the development of hepatic fibrosis.
趋化因子和趋化因子受体有助于肝星状细胞（HSC）和库普弗细胞的迁移，这两种细胞类型是纤维化形成中的关键细胞。在此，我们研究单核细胞趋化蛋白（MCP）-1、MCP-2和MCP-3的受体CCR2在肝纤维化中的作用。胆管结扎（BDL）后，肝脏中CCR2、MCP-1、MCP-2和MCP-3信使核糖核酸表达增加。库普弗细胞和肝星状细胞均表达CCR2，但肝细胞不表达。通过胶原沉积、α平滑肌肌动蛋白表达和肝脏羟脯氨酸含量评估，CCR2基因敲除（-/-）小鼠中BDL和四氯化碳（CCl₄）诱导的纤维化明显减轻。我们通过氯膦酸盐、照射和骨髓（BM）移植相结合的方法构建了CCR2嵌合小鼠，使库普弗细胞能够完全由BM细胞重建，但肝星状细胞不能。含有野生型BM的嵌合小鼠巨噬细胞募集增加，而含有CCR2（-/-）BM的嵌合小鼠在BDL后5天巨噬细胞募集较少。尽管BM中表达的CCR2在损伤早期增强了巨噬细胞募集，但在慢性纤维化模型中，包括肝星状细胞在内的驻留肝细胞而非BM上的CCR2表达是纤维化反应所必需 的。体外实验表明，缺乏CCR2（-/-）或其下游介质p47phox（-/-）的肝星状细胞对MCP-1、MCP-2和MCP-3不表现出细胞外信号调节激酶和AKT磷酸化、趋化性或活性氧产生。
我们的结果表明，CCR2促进肝星状细胞趋化和肝纤维化的发展。
