Inhibition of TLR4 Signalling-Induced Inflammation Attenuates Secondary Injury after Diffuse Axonal Injury in Rats

Increasing evidence suggests that secondary injury after diffuse axonal injury (DAI) damages more axons than the initial insult, but the underlying mechanisms of this phenomenon are not fully understood. Recent studies show that toll-like receptor 4 (TLR4) plays a critical role in promoting adaptive...

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Main Authors: Yonglin Zhao, Yahui Zhao, Ming Zhang, Junjie Zhao, Xudong Ma, Tingqin Huang, Honggang Pang, Jiaxi Li, Jinning Song
Format: Article
Language:English
Published: Wiley 2016-01-01
Series:Mediators of Inflammation
Online Access:http://dx.doi.org/10.1155/2016/4706915
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author Yonglin Zhao
Yahui Zhao
Ming Zhang
Junjie Zhao
Xudong Ma
Tingqin Huang
Honggang Pang
Jiaxi Li
Jinning Song
author_facet Yonglin Zhao
Yahui Zhao
Ming Zhang
Junjie Zhao
Xudong Ma
Tingqin Huang
Honggang Pang
Jiaxi Li
Jinning Song
author_sort Yonglin Zhao
collection DOAJ
description Increasing evidence suggests that secondary injury after diffuse axonal injury (DAI) damages more axons than the initial insult, but the underlying mechanisms of this phenomenon are not fully understood. Recent studies show that toll-like receptor 4 (TLR4) plays a critical role in promoting adaptive immune responses and have been shown to be associated with brain damage. The purpose of this study was to investigate the role of the TLR4 signalling pathway in secondary axonal injury in the cortices of DAI rats. TLR4 was mainly localized in microglial cells and neurons, and the levels of TLR4 downstream signalling molecules, including TLR4, myeloid differentiation primary response gene 88, toll/IR-1-(TIR-) domain-containing adaptor protein inducing interferon-beta, interferon regulatory factor 3, interferon β, nuclear factor κB (NF-κB) p65, and phospho-NF-κB p65, significantly increased and peaked at 1 d after DAI. Inhibition of TLR4 by TAK-242 attenuated apoptosis, neuronal and axonal injury, and glial responses. The neuroprotective effects of TLR4 inhibition were associated with decreases in the levels of TLR4 downstream signalling molecules and inflammatory factors, including interleukin-1β, interleukin-6, and tumour necrosis factor-α. These results suggest that the TLR4 signalling pathway plays an important role in secondary injury and may be an important therapeutic target following DAI.
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spelling doaj-art-9d6b17f875664f8e9922f4985f67cbc82025-02-03T05:51:34ZengWileyMediators of Inflammation0962-93511466-18612016-01-01201610.1155/2016/47069154706915Inhibition of TLR4 Signalling-Induced Inflammation Attenuates Secondary Injury after Diffuse Axonal Injury in RatsYonglin Zhao0Yahui Zhao1Ming Zhang2Junjie Zhao3Xudong Ma4Tingqin Huang5Honggang Pang6Jiaxi Li7Jinning Song8Department of Neurosurgery, The First Affiliated Hospital of Xi’an Jiaotong University, 277 West Yanta Road, Xi’an, Shaanxi 710061, ChinaDepartment of Neurosurgery, The First Affiliated Hospital of Xi’an Jiaotong University, 277 West Yanta Road, Xi’an, Shaanxi 710061, ChinaDepartment of Neurosurgery, The Second Affiliated Hospital of Xi’an Jiaotong University, No. 157 of Xiwu Road, Xi’an, Shaanxi 710004, ChinaDepartment of Neurosurgery, The First Affiliated Hospital of Xi’an Jiaotong University, 277 West Yanta Road, Xi’an, Shaanxi 710061, ChinaDepartment of Neurosurgery, The First Affiliated Hospital of Xi’an Jiaotong University, 277 West Yanta Road, Xi’an, Shaanxi 710061, ChinaDepartment of Neurosurgery, The First Affiliated Hospital of Xi’an Jiaotong University, 277 West Yanta Road, Xi’an, Shaanxi 710061, ChinaDepartment of Neurosurgery, The First Affiliated Hospital of Xi’an Jiaotong University, 277 West Yanta Road, Xi’an, Shaanxi 710061, ChinaDepartment of Neurosurgery, The First Affiliated Hospital of Xi’an Jiaotong University, 277 West Yanta Road, Xi’an, Shaanxi 710061, ChinaDepartment of Neurosurgery, The First Affiliated Hospital of Xi’an Jiaotong University, 277 West Yanta Road, Xi’an, Shaanxi 710061, ChinaIncreasing evidence suggests that secondary injury after diffuse axonal injury (DAI) damages more axons than the initial insult, but the underlying mechanisms of this phenomenon are not fully understood. Recent studies show that toll-like receptor 4 (TLR4) plays a critical role in promoting adaptive immune responses and have been shown to be associated with brain damage. The purpose of this study was to investigate the role of the TLR4 signalling pathway in secondary axonal injury in the cortices of DAI rats. TLR4 was mainly localized in microglial cells and neurons, and the levels of TLR4 downstream signalling molecules, including TLR4, myeloid differentiation primary response gene 88, toll/IR-1-(TIR-) domain-containing adaptor protein inducing interferon-beta, interferon regulatory factor 3, interferon β, nuclear factor κB (NF-κB) p65, and phospho-NF-κB p65, significantly increased and peaked at 1 d after DAI. Inhibition of TLR4 by TAK-242 attenuated apoptosis, neuronal and axonal injury, and glial responses. The neuroprotective effects of TLR4 inhibition were associated with decreases in the levels of TLR4 downstream signalling molecules and inflammatory factors, including interleukin-1β, interleukin-6, and tumour necrosis factor-α. These results suggest that the TLR4 signalling pathway plays an important role in secondary injury and may be an important therapeutic target following DAI.http://dx.doi.org/10.1155/2016/4706915
spellingShingle Yonglin Zhao
Yahui Zhao
Ming Zhang
Junjie Zhao
Xudong Ma
Tingqin Huang
Honggang Pang
Jiaxi Li
Jinning Song
Inhibition of TLR4 Signalling-Induced Inflammation Attenuates Secondary Injury after Diffuse Axonal Injury in Rats
Mediators of Inflammation
title Inhibition of TLR4 Signalling-Induced Inflammation Attenuates Secondary Injury after Diffuse Axonal Injury in Rats
title_full Inhibition of TLR4 Signalling-Induced Inflammation Attenuates Secondary Injury after Diffuse Axonal Injury in Rats
title_fullStr Inhibition of TLR4 Signalling-Induced Inflammation Attenuates Secondary Injury after Diffuse Axonal Injury in Rats
title_full_unstemmed Inhibition of TLR4 Signalling-Induced Inflammation Attenuates Secondary Injury after Diffuse Axonal Injury in Rats
title_short Inhibition of TLR4 Signalling-Induced Inflammation Attenuates Secondary Injury after Diffuse Axonal Injury in Rats
title_sort inhibition of tlr4 signalling induced inflammation attenuates secondary injury after diffuse axonal injury in rats
url http://dx.doi.org/10.1155/2016/4706915
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