Zhang Xiaohui, Lou Jinli, Bai Li, Chen Yu, Zheng Sujun, Duan Zhongping
Artificial Liver Treatment Center, Beijing YouAn Hospital, Capital Medical University, Beijing, China (mainland).
Clinical Laboratory Center, Beijing YouAn Hospital, Capital Medical University, Beijing, China (mainland).
Med Sci Monit. 2017 Feb 25;23:1009-1016. doi: 10.12659/msm.899725.
BACKGROUND Liver fibrosis is the result of chronic inflammation and repair, and many immune cells contribute to the process. Regulatory T cells (Tregs) mediate immune tolerance and are highly expressed in liver fibrosis. However, few reports have studied the specific effects of Tregs on regulating immune cells in liver fibrosis. The present study aimed to investigate the regulation of Tregs on intrahepatic immune cells in liver fibrosis by depleting Tregs in mice. MATERIAL AND METHODS Liver fibrosis was induced by carbon tetrachloride, and an anti-CD25 mAb (PC61) was used to deplete Tregs. Liver fibrosis and injury were reflected by immunofluorescence staining and alanine aminotransferase level. The expressions of immune cell Tregs and cytokines were detected by flow cytometry and/or real-time PCR. Interferon-γ (IFN-γ) concentration was measured by ELISA. RESULTS Tregs were rich in fibrotic livers; after Tregs depletion, the intrahepatic CD4+ T cell and Kupffer cells (KC) populations did not change compared with liver fibrosis, but CD8+ T cells were slightly elevated. However, natural killer (NK) cells and IFN-g levels were significantly decreased in fibrosis and increased after Tregs depletion. Interesting, we found Tregs promoted KC M1/M2 balance to M2, because inducible nitric oxide synthase (M1) was increased but arginase-1 (M2) was reduced after depleting Tregs. Furthermore, in isolated KCs from livers, IL-12 (M1) was increased, but TGF-β (M2) was reduced after depleting Tregs, compared with fibrotic livers. CONCLUSIONS Tregs are involved in the immune regulation of liver fibrosis, primarily by suppressing NK cells and M1 KCs, and mildly suppressing CD8+ T cells.
肝纤维化是慢性炎症和修复的结果，许多免疫细胞参与这一过程。调节性T细胞（Tregs）介导免疫耐受，在肝纤维化中高表达。然而，很少有报道研究Tregs对肝纤维化中免疫细胞调节的具体作用。本研究旨在通过清除小鼠体内的Tregs来研究其对肝纤维化肝内免疫细胞的调节作用。
用四氯化碳诱导肝纤维化，并用抗CD25单克隆抗体（PC61）清除Tregs。通过免疫荧光染色和丙氨酸转氨酶水平反映肝纤维化和损伤情况。通过流式细胞术和/或实时PCR检测免疫细胞Tregs和细胞因子的表达。用ELISA法检测干扰素-γ（IFN-γ）浓度。
Tregs在纤维化肝脏中丰富；清除Tregs后，与肝纤维化相比，肝内CD4+T细胞和库普弗细胞（KC）数量没有变化，但CD8+T细胞略有升高。然而，自然杀伤（NK）细胞和IFN-γ水平在纤维化时显著降低，清除Tregs后升高。有趣的是，我们发现Tregs促进KC的M1/M平衡向M2转变，因为清除Tregs后诱导型一氧化氮合酶（M1）增加而精氨酸酶-1（M2）减少。此外，与纤维化肝脏相比，从肝脏分离的KC中，清除Tregs后IL-12（M1）增加，但TGF-β（M2）减少。
Tregs参与肝纤维化的免疫调节，主要通过抑制NK细胞和M1 KC，轻度抑制CD8+T细胞。
