Gene Therapy and Hepatology Area, Center for Applied Medical Research (CIMA), University of Navarra, Pamplona, Spain.
J Hepatol. 2011 Mar;54(3):422-31. doi: 10.1016/j.jhep.2010.07.014. Epub 2010 Sep 26.
BACKGROUND & AIMS: The mechanisms by which Foxp3+ T regulatory cells (Treg) accumulate in HCV infected livers are not known. Here, we studied the role of chemokines CCL17 and CCL22 in this process.
Chemokine mRNA levels were determined by qPCR in liver biopsies from 26 HCV chronically infected patients (CHC), 11 patients with treatment-induced sustained virological response (SVR), 16 patients with other liver diseases unrelated to HCV, and 24 normal livers. Double-immunofluorescence Foxp3/CD3 or CD11c/CCL22 was performed in liver sections. Chemokine production by monocyte-derived dendritic cells (MDDC) co-cultured with uninfected or HCV-JFH1 infected Huh7 cells was measured by qPCR and ELISA. Chemotactic activity of culture supernatants was also tested.
Foxp3+ Treg were increased in CHC livers as compared to controls. Patients with CHC showed elevated intrahepatic levels of CCL17 mRNA compared to normal livers or livers from subjects with SVR or other forms of liver disease. Intrahepatic CCL22 expression was also higher in CHC than in healthy subjects or SVR patients but similar to that observed in other liver diseases. Dendritic cells producing CCL22 could be found inside the hepatic lobule in CHC patients. Contact between MDDC and HCV-JFH1-infected Huh7 cells induced the expression of CCL17 and CCL22 in a process partially dependent on ICAM-1. Transwell experiments showed that upregulation of these chemokines enhanced Treg migration.
Contact of HCV-infected cells with dendritic cells induces the production of Treg-attracting chemokines, an effect which may favour liver accumulation of Treg in CHC. Our findings contribute to explain the mechanism by which HCV escapes the immune response and thus reveals novel therapeutic targets.
Foxp3+T 调节细胞（Treg）在 HCV 感染的肝脏中积累的机制尚不清楚。在这里，我们研究了趋化因子 CCL17 和 CCL22 在这个过程中的作用。
通过 qPCR 测定 26 例慢性 HCV 感染患者（CHC）、11 例治疗诱导持续病毒学应答（SVR）患者、16 例与 HCV 无关的其他肝病患者和 24 例正常肝脏的肝活检组织中的趋化因子 mRNA 水平。对肝组织切片进行 Foxp3/CD3 或 CD11c/CCL22 的双重免疫荧光染色。通过 qPCR 和 ELISA 检测单核细胞来源的树突状细胞（MDDC）与未感染或 HCV-JFH1 感染的 Huh7 细胞共培养时趋化因子的产生。还测试了培养上清液的趋化活性。
与对照组相比，CHC 肝脏中的 Foxp3+Treg 增加。与正常肝脏或 SVR 患者或其他肝病患者相比，CHC 患者肝内 CCL17 mRNA 水平升高。CHC 患者肝内 CCL22 表达也高于健康受试者或 SVR 患者，但与其他肝病患者相似。在 CHC 患者中，可在肝小叶内发现产生 CCL22 的树突状细胞。MDDC 与 HCV-JFH1 感染的 Huh7 细胞接触可诱导 CCL17 和 CCL22 的表达，这一过程部分依赖于 ICAM-1。Transwell 实验表明，这些趋化因子的上调增强了 Treg 的迁移。
HCV 感染细胞与树突状细胞的接触诱导 Treg 趋化因子的产生，这一效应可能有利于 CHC 中 Treg 在肝脏中的积累。我们的发现有助于解释 HCV 逃避免疫反应的机制，从而揭示新的治疗靶点。
