Basic Study
Copyright ©The Author(s) 2019. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jun 28, 2019; 25(24): 3044-3055
Published online Jun 28, 2019. doi: 10.3748/wjg.v25.i24.3044
Effect of NLRC5 on activation and reversion of hepatic stellate cells by regulating the nuclear factor-κB signaling pathway
Yan-Zhen Zhang, Jian-Ning Yao, Lian-Feng Zhang, Chun-Feng Wang, Xue-Xiu Zhang, Bing Gao
Yan-Zhen Zhang, Jian-Ning Yao, Lian-Feng Zhang, Chun-Feng Wang, Xue-Xiu Zhang, Bing Gao, Department of Second Gastroenterology, the First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, Henan Province, China
Author contributions: Zhang YZ, Yao JN, and Zhang LF designed the research; Zhang YZ, Yao JN, and Wang CF performed the research; Zhang LF and Wang CF contributed new reagents and analytic tools; Zhang XX and Gao B analyzed the data; Zhang YZ, Yao JN, Zhang LF, Wang CF, Zhang XX, and Gao B wrote the paper.
Institutional review board statement: The study was approved by the ethics committee of the First Affiliated Hospital of Zhengzhou University.
Institutional animal care and use committee statement: The study was approved by the institutional animal care and use committee of the First Affiliated Hospital of Zhengzhou University.
Conflict-of-interest statement: The authors declare that they have no competing interests.
Data sharing statement: No additional data are available.
ARRIVE guidelines statement: The authors have read the ARRIVE guidelines, and the manuscript was prepared and revised according to the ARRIVE guidelines.
Open-Access: This is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Corresponding author: Yan-Zhen Zhang, MD, Doctor, Department of Second Gastroenterology, the First Affiliated Hospital of Zhengzhou University, No. 1, Jianshe East Road, Zhengzhou 450052, Henan Province, China. zhangyz8848@163.com
Telephone: +86-371-66271117
Received: March 20, 2019
Peer-review started: March 20, 2019
First decision: April 4, 2019
Revised: April 27, 2019
Accepted: June 1, 2019
Article in press: June 1, 2019
Published online: June 28, 2019
Processing time: 101 Days and 5 Hours
Abstract
BACKGROUND

The formation of liver fibrosis is mainly caused by the activation of hepatic stellate cells (HSCs) and the imbalance of extracellular matrix (ECM) production and degradation. The treatment of liver fibrosis mainly includes removing the cause, inhibiting the activation of HSCs, and inhibiting inflammation. NOD-like receptor (NLR) family, caspase activation and recruitment domain (CARD) domain containing 5/NOD27/CLR16.1 (NLRC5) is a highly conserved member of the NLR family and is involved in inflammation and immune responses by regulating various signaling pathways such as nuclear factor-κB (NF-κB) signaling. It has been found that NLRC5 plays an important role in liver fibrosis, but its specific effect and possible mechanism remain to be fully elucidated.

AIM

To investigate the role of NLRC5 in the activation and reversion of HSCs induced with transforming growth factor-β (TGF-β) and MDI, and to explore its relationship with liver fibrosis.

METHODS

A total of 24 male C57BL/6 mice were randomly divided into three groups, including normal, fibrosis, and recovery groups. Twenty-four hours after a liver fibrosis and spontaneous reversion model was established, the mice were sacrificed and pathological examination of liver tissue was performed to observe the degree of liver fibrosis in each group. LX-2 cells were cultured in vitro and treated with TGF-β1 and MDI. Real-time quantitative PCR (qPCR) and Western blot were used to analyze the expression levels of NLRC5, α-smooth muscle actin (α-SMA), and collagen type I alpha1 (Col1a1) in each group. The activity of NF-κB in each group of cells transfected with NLRC5-siRNA was detected.

RESULTS

Compared with the normal mice, the expression level of NLRC5 increased significantly (P < 0.01) in the fibrosis group, but decreased significantly in the recovery group (P < 0.01). In in vitro experiments, the content of NLRC5 was enhanced after TGF-β1 stimulation and decreased to a lower level when treated with MDI (P < 0.01). The expression of α-SMA and Col1a1 proteins and mRNAs in TGF-β1-mediated cells was suppressed by transfection with NLRC5-siRNA (P < 0.01). Western blot analysis showed that the expression of NF-κB p65 protein and phosphorylated IκBα (p-IκBα) was increased in the liver of mice in the fibrosis group but decreased in the recovery group (P < 0.01), and the protein level of nuclear p65 and p-IκBα was significantly increased after treatment with NLRC5-siRNA (P < 0.01).

CONCLUSION

NLRC5 may play a key role in the development and reversal of hepatic fibrosis through the NF-κB signaling pathway, and it is expected to be one of the clinical therapeutic targets.

Keywords: NLRC5; Hepatic stellate cells; Liver fibrosis; Recovery

Core tip: Liver fibrosis is a pathological tissue repair process characterized by excessive deposition of extracellular matrix in the liver, accompanied by inflammation, and eventually progresses to cirrhosis. Several recent reports have shown that effective treatment can reverse liver fibrosis, which is associated with inactivation of hepatic stellate cells (HSCs) and multiple signaling pathways. NOD-like receptor (NLR) family, caspase activation and recruitment domain (CARD) domain containing 5/NOD27/CLR16.1 (NLRC5) is the largest member of the NLR family and is highly expressed in immune tissues or organs such as the spleen, lung, thymus, and liver, mediating inflammation inhibition and antiviral response. This study aimed to investigate the role of NLRC5 in activating and devitalization of HSCs and its mechanism. The results demonstrate that NLRC5 may be involved in the development and reversal of liver fibrosis by negative regulation of nuclear factor-κB.