Role of the TLR4 pathway in blood-spinal cord barrier dysfunction during the bimodal stage after ischemia/reperfusion injury in rats
Authors: Hong Ma
Wen-Fei Tan
Huang-Wei Lv
Bo Fang
Xiao-Qian Li
He Wang
Journal: Journal of Neuroinflammation (2014)
Discipline: NEUROSCIENCE & BEHAVIOR
Keywords: Spinal cord ischemia-reperfusion; TLR₄ pathway; BSCB dysfunction; MyD₈₈-dependent pathway; TRIF-dependent pathway
Affiliations: Department of Anesthesiology, First Affiliated Hospital, China Medical University, Shenyang 110001, Liaoning, China. .

Abstract:  Background: Spinal cord ischemia-reperfusion (I/R) involves two-phase injury, including an initial acute ischemic insult and subsequent inflammatory reperfusion injury, resulting in blood-spinal cord barrier (BSCB) dysfunction involving the TLR₄ pathway. However, the correlation between TLR₄/MyD₈₈-dependent and TLR₄/TRIF-dependent pathways in BSCB dysfunction is not fully understood. The aim of this study is to characterize inflammatory responses in spinal cord I/R and the events that define its clinical progression with delayed neurological deficits, supporting a bimodal mechanism of injury. Methods: Rats were intrathecally pretreated with TAK-242, MyD₈₈ inhibitory peptide, or Resveratrol at a 12 h interval for 3 days before undergoing 14-minute occlusion of aortic arch. Evan's Blue (EB) extravasation and water content were detected at 6, 12, 18, 24, 36, 48, and 72 h after reperfusion. EB extravasation, water content, and NF-κB activation were increased with time after reperfusion, suggesting a bimodal distribution, as maximal increasing were detected at both 12 and 48 h after reperfusion. The changes were directly proportional to TLR₄ levels determined by Western blot. Double-labeled immunohistochemical analysis was also used to detect the relationship between different cell types of BSCB with TLR₄. Furthermore, NF-κB and IL-1β were analyzed at 12 and 48 h to identify the correlation between MyD₈₈-dependent and TRIF-dependent pathways. Results: Rats without functional TLR₄ and MyD₈₈ attenuated BSCB leakage and inflammatory responses at 12 h, suggesting the ischemic event was largely mediated by MyD₈₈-dependent pathway. Similar protective effects observed in rats with depleted TLR₄, MyD₈₈, and TRIF receptor at 48 h infer that the ongoing inflammation which occurred in late phase was mainly initiated by TRIF-dependent pathway and such inflammatory response could be further amplified by MyD₈₈-dependent pathway. Additionally, microglia appeared to play a major role in early phase of inflammation after I/R injury, while in late responding phase both microglia and astrocytes were necessary. Conclusions: These findings indicate the relevance of TLR4/MyD₈₈-dependent and TLR₄/TRIF-dependent pathways in bimodal phases of inflammatory responses after I/R injury, corresponding with the clinical progression of injury and delayed onset of symptoms. The clinical usage of TLR₄ signaling inhibitors at different phases may be a therapeutic option for the prevention of delayed injury. 

Retracted: No

PubPeer comments:
 1h and 48h basically identical ![file] Disclaimer: These potential image duplications have been detected automatically using ImageTwin http: dx.doi.org 10.1145 3019612.3019875 Although results have been curated, the automatic algorithm may have generated false positive results and cannot take into account all scientific explanations for apparent duplications like stripped and reprobed blots, time series, serial sections and reused controls. , 
 #1 I agree with this finding; images are repeated after rotation. TAM. *** ![file] ,