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Abstract：
BACKGROUND: The liver regeneration is a highly complicated process depending on the close cooperations between the hepatocytes and non-parenchymal cells involving various inflammatory cells. Here, we explored the role of myeloid-derived suppressor cells (MDSCs) in the processes of liver regeneration and liver fibrosis after liver injury.
METHODS: We established four liver injury models of mice including CCl4-induced liver injury model, bile duct ligation (BDL) model, concanavalin A (Con A)-induced hepatitis model, and lipopolysaccharide (LPS)-induced hepatitis model. The intrahepatic levels of MDSCs (CD11b+Gr-1+) after the liver injury were detected by flow cytometry. The effects of MDSCs on liver tissues were analyzed in the transwell co-culture system, in which the MDSCs cytokines including IL-10, VEGF, and TGF-β were measured by ELISA assay and followed by being blocked with specific antibodies.
RESULTS: The intrahepatic infiltrations of MDSCs with surface marker of CD11b+Gr-1+ remarkably increased after the establishment of four liver injury models. The blood served as the primary reservoir for hepatic recruitment of MDSCs during the liver injury, while the bone marrow appeared play a compensated role in increasing the number of MDSCs at the late stage of the inflammation. The recruited MDSCs in injured liver were mainly the M-MDSCs (CD11b+Ly6G-Ly6Chigh) featured by high expression levels of cytokines including IL-10, VEGF, and TGF-β. Co-culture of the liver tissues with MDSCs significantly promoted the proliferation of both hepatocytes and hepatic stellate cells (HSCs).
CONCLUSIONS: The dramatically and quickly infiltrated CD11b+Gr-1+ MDSCs in injured liver not only exerted pro-proliferative effects on hepatocytes, but also accounted for the activation of profibrotic HSCs.
METHODS: We established four liver injury models of mice including CCl4-induced liver injury model, bile duct ligation (BDL) model, concanavalin A (Con A)-induced hepatitis model, and lipopolysaccharide (LPS)-induced hepatitis model. The intrahepatic levels of MDSCs (CD11b+Gr-1+) after the liver injury were detected by flow cytometry. The effects of MDSCs on liver tissues were analyzed in the transwell co-culture system, in which the MDSCs cytokines including IL-10, VEGF, and TGF-β were measured by ELISA assay and followed by being blocked with specific antibodies.
RESULTS: The intrahepatic infiltrations of MDSCs with surface marker of CD11b+Gr-1+ remarkably increased after the establishment of four liver injury models. The blood served as the primary reservoir for hepatic recruitment of MDSCs during the liver injury, while the bone marrow appeared play a compensated role in increasing the number of MDSCs at the late stage of the inflammation. The recruited MDSCs in injured liver were mainly the M-MDSCs (CD11b+Ly6G-Ly6Chigh) featured by high expression levels of cytokines including IL-10, VEGF, and TGF-β. Co-culture of the liver tissues with MDSCs significantly promoted the proliferation of both hepatocytes and hepatic stellate cells (HSCs).
CONCLUSIONS: The dramatically and quickly infiltrated CD11b+Gr-1+ MDSCs in injured liver not only exerted pro-proliferative effects on hepatocytes, but also accounted for the activation of profibrotic HSCs.
摘要：
背景：肝脏再生是一个非常复杂的过程，取决于肝细胞和涉及各种炎症细胞的非实质细胞之间的密切合作。这里,我们探讨了骨髓来源的抑制细胞（MDSCs）在肝损伤后肝再生和肝纤维化过程中的作用。
方法：我们建立了四种小鼠肝损伤模型，包括CCl4诱导的肝损伤模型，胆管结扎（BDL）模型，伴刀豆球蛋白A（ConA）诱导的肝炎模型，和脂多糖（LPS）诱导的肝炎模型。流式细胞术检测肝损伤后肝内MDSCs(CD11b+Gr-1+)水平。在transwell共培养系统中分析MDSCs对肝组织的影响,其中MDSCs细胞因子包括IL-10、VEGF、和TGF-β通过ELISA测定，然后用特异性抗体阻断。
结果：建立4种肝损伤模型后，表面标记为CD11b+Gr-1+的MDSCs肝内浸润明显增加。在肝损伤期间，血液作为MDSCs肝募集的主要储库，而骨髓在炎症晚期出现时对增加MDSCs的数量起代偿作用。在损伤的肝脏中招募的MDSCs主要是M-MDSCs（CD11bLy6G-Ly6Clhigh），具有高表达水平的细胞因子，包括IL-10，VEGF，和TGF-β。肝组织与MDSC的共培养显着促进肝细胞和肝星状细胞（HSC）的增殖。
结论：在损伤的肝脏中迅速迅速浸润的CD11b+Gr-1+MDSCs不仅对肝细胞产生促增殖作用，但也是促纤维化HSC的激活原因。
方法：我们建立了四种小鼠肝损伤模型，包括CCl4诱导的肝损伤模型，胆管结扎（BDL）模型，伴刀豆球蛋白A（ConA）诱导的肝炎模型，和脂多糖（LPS）诱导的肝炎模型。流式细胞术检测肝损伤后肝内MDSCs(CD11b+Gr-1+)水平。在transwell共培养系统中分析MDSCs对肝组织的影响,其中MDSCs细胞因子包括IL-10、VEGF、和TGF-β通过ELISA测定，然后用特异性抗体阻断。
结果：建立4种肝损伤模型后，表面标记为CD11b+Gr-1+的MDSCs肝内浸润明显增加。在肝损伤期间，血液作为MDSCs肝募集的主要储库，而骨髓在炎症晚期出现时对增加MDSCs的数量起代偿作用。在损伤的肝脏中招募的MDSCs主要是M-MDSCs（CD11bLy6G-Ly6Clhigh），具有高表达水平的细胞因子，包括IL-10，VEGF，和TGF-β。肝组织与MDSC的共培养显着促进肝细胞和肝星状细胞（HSC）的增殖。
结论：在损伤的肝脏中迅速迅速浸润的CD11b+Gr-1+MDSCs不仅对肝细胞产生促增殖作用，但也是促纤维化HSC的激活原因。
