Basic Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Jul 21, 2015; 21(27): 8314-8325
Published online Jul 21, 2015. doi: 10.3748/wjg.v21.i27.8314
TLR4-HMGB1-, MyD88- and TRIF-dependent signaling in mouse intestinal ischemia/reperfusion injury
Jie Wang, Gui-Zhen He, Yu-Kang Wang, Qian-Kun Zhu, Wei Chen, Tai Guo
Jie Wang, Gui-Zhen He, Yu-Kang Wang, Qian-Kun Zhu, Wei Chen, Department of Parenteral and Enteral Nutrition, Peking Union Medical College Hospital, Centre for Translational Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100730, China
Tai Guo, National Institutes for Food and Drug Control, Beijing 100050, China
Author contributions: Wang J, Wang YK, Zhu QK, Chen W, and Guo T performed the animal experiments; Wang J and Chen W performed the research; Zhu QK collected the data; Wang J analyzed the data and wrote the paper; He GZ designed the research and was also involved in editing the manuscript.
Supported by National Natural Science Foundation of China, No. 30940069; and the Natural Sciences Foundation of Beijing, No.7102127.
Institutional review board statement: The study was reviewed and approved by the Academic Committee of Chinese Academy of Medical Sciences and Peking Union Medical College Hospital Institutional Review Board.
Institutional animal care and use committee statement: All procedures involving animals were reviewed and approved by the Institutional Animal Care and Use Committee of the Academic Committee of Chinese Academy of Medical Sciences and Peking Union Medical College Hospital (IACUC protocol number:XHDW-2013-008).
Conflict-of-interest statement: The authors declare no conflict of interests.
Data sharing statement: No additional data are available.
Open-Access: This article is an open-access article which 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/
Correspondence to: Gui-Zhen He, Professor, Department of Parenteral and Enteral Nutrition, Peking Union Medical College Hospital, Centre for Translational Medicine, Chinese Academy of Medical Sciences and Peking Union Medical College, No.1 ShuaifuyuanWangfujing, Dongcheng District, Beijing 100730, China. hgzpumc@163.com
Telephone: +86-10-69154096 Fax: +86-10-69154096
Received: December 22, 2014
Peer-review started: December 23, 2014
First decision: February 10, 2015
Revised: April 1, 2015
Accepted: May 21, 2015
Article in press: May 21, 2015
Published online: July 21, 2015
Abstract

AIM: To characterize high-mobility group protein 1-toll-like receptor 4 (HMGB1-TLR4) and downstream signaling pathways in intestinal ischemia/reperfusion (I/R) injury.

METHODS: Forty specific-pathogen-free male C57BL/6 mice were randomly divided into five groups (n = 8 per group): sham, control, anti-HMGB1, anti-myeloid differentiation gene 88 (MyD88), and anti-translocating-chain-associating membrane protein (TRIF) antibody groups. Vehicle with the control IgG antibody, anti-HMGB1, anti-MyD88, or anti-TRIF antibodies (all 1 mg/kg, 0.025%) were injected via the caudal vein 30 min prior to ischemia. After anesthetization, the abdominal wall was opened and the superior mesenteric artery was exposed, followed by 60 min mesenteric ischemia and then 60 min reperfusion. For the sham group, the abdominal wall was opened for 120 min without I/R. Levels of serum nuclear factor (NF)-κB p65, interleukin (IL)-6, and tumor necrosis factor (TNF)-α were measured, along with myeloperoxidase activity in the lung and liver. In addition,morphologic changes that occurred in the lung and intestinal tissues were evaluated. Levels of mRNA transcripts encoding HMGB1 and NF-κB were measured by real-time quantitative PCR, and levels of HMGB1 and NF-κB protein were measured by Western blot. Results were analyzed using one-way analysis of variance.

RESULTS: Blocking HMGB1, MyD88, and TRIF expression by injecting anti-HMGB1, anti-MyD88, or anti-TRIF antibodies prior to ischemia reduced the levels of inflammatory cytokines in serum; NF-κB p65: 104.64 ± 11.89, 228.53 ± 24.85, 145.00 ± 33.63, 191.12 ± 13.22, and 183.73 ± 10.81 (P < 0.05); IL-6: 50.02 ± 6.33, 104.91 ± 31.18, 62.28 ± 6.73, 85.90 ± 17.37, and 78.14 ± 7.38 (P < 0.05); TNF-α, 43.79 ± 4.18, 70.81 ± 6.97, 52.76 ± 5.71, 63.19 ± 5.47, and 59.70 ± 4.63 (P < 0.05) for the sham, control, anti-HMGB1, anti-MyD88, and anti-TRIF groups, respectively (all in pg/mL).Antibodies also alleviated tissue injury in the lung and small intestine compared with the control group in the mouse intestinal I/R model. The administration of anti-HMGB1, anti-MyD88, and anti-TRIF antibodies markedly reduced damage caused by I/R, for which anti-HMGB1 antibody had the most obvious effect.

CONCLUSION: HMGB1 and its downstream signaling pathway play important roles in the mouse intestinal I/R injury, and the effect of the TRIF-dependent pathway is slightly greater.

Keywords: C57BL/6 mouse, High-mobility group protein 1, Intestinal ischemia-reperfusion injury, Myeloid differentiation gene 88, Nuclear factor-κB translocating-chain-associating membrane protein

Core tip: Intestinal mucosal barrier injury induced by intestinal ischemia/reperfusion is often the basis for a poor prognosis in many diseases. Despite extensive investigative efforts,the underlying mechanism remains a subject of debate, and there are currently no effective methods for its prevention or control. The findings reported here suggest that the high-mobility group protein 1-toll-like receptor 4 axis and the two downstream signaling pathways play important roles in ischemia/reperfusion injury and show potential therapeutic value for their blockade. This study has an important clinical significance, which could improve the survival rate and reduce complications in critically ill patients.