Original Article
Copyright ©2014 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Feb 28, 2014; 20(8): 2062-2070
Published online Feb 28, 2014. doi: 10.3748/wjg.v20.i8.2062
Impaired balance of T helper 17/T regulatory cells in carbon tetrachloride-induced liver fibrosis in mice
Xiao-Fei Sun, Lei Gu, Wen-Sheng Deng, Qing Xu
Xiao-Fei Sun, Lei Gu, Wen-Sheng Deng, Qing Xu, Department of General Surgery, Renji Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai 200127, China
Author contributions: Sun XF and Deng WS performed the majority of experiments and wrote the manuscript; Gu L provided vital reagents and analytical tools and revised the manuscript; Xu Q designed the study and provided financial support for this work.
Supported by Grants for Scientific Research Innovation Project of Shanghai Education Committee, China, No. 13yz040
Correspondence to: Qing Xu, PhD, Department of General Surgery, Renji Hospital, School of Medicine, Shanghai Jiaotong University, No. 160, Pujian Road, Shanghai 200127, China. surgeonxq@hotmail.com
Telephone: +86-21-68383732 Fax: +86-21-68383732
Received: September 8, 2013
Revised: November 1, 2013
Accepted: November 18, 2013
Published online: February 28, 2014
Abstract

AIM: To investigate the effect of T helper (Th) 17/T regulatory (Treg) cells on hepatic fibrosis in mice and its possible mechanism.

METHODS: Hepatic fibrosis was induced by intraperitoneal injection of carbon tetrachloride. Hepatic pathological changes were observed by hematoxylin and eosin staining; the protein levels of interleukin (IL)-6, transforming growth factor (TGF)-β and α-smooth muscle actin (SMA) in liver tissue were determined by Western blotting; and the frequency of Th17 and Treg cells in the liver was estimated by flow cytometry. In addition, hepatic stellate cells were isolated from healthy mouse liver and co-cultured with Th17 or Treg cells. Immunofluorescence staining and Western blotting were performed to determine the change in HSC activation.

RESULTS: In the model group, there were different degrees of fibroplasia, degeneration and necrosis. The protein levels of IL-6, TGF-β and α-SMA in liver tissue were significantly higher than those in the control group at 12 wk (P < 0.05). Compared with the control group, the frequency of Th17 cells in the model group was increased but the frequency of Treg cells decreased gradually. Furthermore, at 4, 8 and 12 wk, there were significant differences in the number of Th17 cells (0.52% ± 0.16%, 1.46% ± 0.24%, and 2.60% ± 0.41%, respectively, P < 0.05) and Treg cells (2.99% ± 0.40%, 2.16% ± 0.50%, and 1.49% ± 0.34%, respectively, P < 0.05). In vitro, Th17 cells promoted, whereas Treg cells inhibited the expression of α-SMA, both in a dose-dependent manner, compared with the control group.

CONCLUSION: Th17/Treg imbalance exists in mice with liver fibrosis, which potentially promotes liver fibrosis via HSC activation.

Keywords: T helper 17 cell, Treg cell, Carbon tetrachloride, Hepatic fibrosis, Hepatic stellate cell

Core tip: It has been reported that T helper (Th) 17/T regulatory (Treg) cell imbalance is closely related to many autoimmune diseases. The role of Th17/Treg imbalance in liver fibrosis has seldom been reported. Our study focused on the change in Th17/Treg balance in a liver fibrosis model in mice, and explored the possible mechanism through which the development of fibrosis is regulated. The frequency of Th17 cells increased, while the frequency of Treg cells decreased in liver fibrosis. These changes promote the occurrence of liver fibrosis via hepatic stellate cell activation.