Ji-Xin Shi

Effect of systemic LPS injection on cortical NF-κB activity and inflammatory response following traumatic brain injury in rats

The aim of current study is to investigate the effect of systemic administration of lipopolysaccharide (LPS) on the temporal pattern of cortical nuclear factor kappa B (NF-kappaB) binding activity, inflammatory response and secondary damage in the injured brain following traumatic brain injury (TBI). Right parietal cortical contusion in rats was made by using weight-dropping method. The rats were randomly divided into sham, LPS, TBI and TBI-LPS groups, with LPS injected intraperitoneally. NF-kappaB binding activity, cytokines, intercellular adhesion molecule-1 (ICAM-1) and brain damage were detected by electrophoretic mobility shift assay (EMSA), enzyme-linked immunosorbent assay (ELISA), immunohistochemistry and terminal deoxynucleotidyl-transferase-mediated biotin-dUTP nick end labeling (TUNEL) apoptosis, respectively. The results showed that systemic administration of LPS following TBI could induce an immediate, strong and persistent upregulation of NF-kappaB, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and ICAM-1 in the area surrounding the injured brain. As compared with rats of sham, LPS and TBI groups, NF-kappaB binding activity, TNF-alpha and IL-6 were significantly upregulated in the surrounding cortex of injured site as early as 3 h postinjury when challenged with LPS, kept at high level up to 7-days postinjury. ICAM-1-positive vessels and apoptotic TUNEL-positive cells in the injured brain were also significantly increased in TBI-LPS rats. It was concluded that inflammatory response and secondary brain damage occurred in the injured brain could be highly exacerbated by endotoxemia.

Cortical expression of nuclear factor κB after human brain contusion

Abstract The aim of current study was to analyze the binding activity and the temporal and cellular expression of nuclear factor kappa B (NF-κB) in human contused brain. Eighteen contused brain samples were obtained from 17 patients undergoing surgery for brain contusions 5–80xa0h after trauma. NF-κB binding activity was detected by electrophoretic mobility shift assay (EMSA), and temporal and cellular expression of NF-κB subunits p65 and p50 was analyzed by immunohistochemistry. The results showed that a progressive upregulation of NF-κB activity occurred in the area surrounding the injured brain with the time from brain trauma to operation. The maximal expression of NF-κB was detected after 48xa0h postinjury. The expression of NF-κB p65 was mainly located at glial and vascular endothelial cells without expression at neurons. The expression of NF-κB p50 was mainly located at glial cells, a little at neurons and no expression at vascular endothelial cells. Within 24xa0h postinjury, both NF-κB p65 and p50 immunoreactivity was mainly observed in the nucleus of cells. After 24xa0h postinjury, NF-κB p65 labeling was found in the both nucleus and cytoplasm of glial and endothelial cells; otherwise, p50 labeling was primarily found in the nucleus of glial cells and in the nucleus, cytoplasm and process of neurons. It is concluded that NF-κB could be highly upregulated at human contused brain and the cellular pattern of p65 and p50 expression might be closely associated with the cell functions.

Concomitant upregulation of nuclear factor-kB activity, proinflammatory cytokines and ICAM-1 in the injured brain after cortical contusion trauma in a rat model

BACKGROUNDnNuclear factor kappa B (NF-kB), proinflammatory cytokines and intercellular adhesion molecule 1 (ICAM-1) are frequently upregulated in the injured brain after traumatic brain injury (TBI). However, the temporal pattern of upregulation is not well defined.nnnAIMSnThe current study was undertaken to investigate the temporal profile of the expression of NF-kB, proinflammatory cytokines and ICAM-1 in the injured brain after cortical contusion trauma of the rat brain.nnnSETTINGS AND DESIGNnA rat model of cortical contusion was produced by a free-falling weight on the exposed dura of right parietal lobe. The rats were randomly divided into control group and TBI groups at hours 3, 12, 24 and 72, and on day 7.nnnMATERIAL AND METHODSnNF-kB binding activity in the surrounding brain of injured area was studied by electrophoretic mobility shift assay (EMSA). The levels of TNF-alpha and IL-6 were detected using ELISA and ICAM-1 expression studied by immunohistochemistry.nnnSTATISTICAL ANALYSISnThe data were analyzed by one-way ANOVA followed by Student-Newman-Keuls post hoc test. Relation between variables was analyzed using bivariate correlation with two-tailed test.nnnRESULTSnCompared with that of control group, NF-kB binding activity in the injured brain was significantly increased through 12 h and 7 days postinjury, with the maximum at 72 h. The concentrations of TNF-alpha and IL-6 in the injured brain were significantly increased from 3 h to 7 days and maximal at 24 h postinjury. The number of ICAM-1 immunostained microvessels was significantly increased in the injured brain from 24 h to 7 days postinjury, with its peak at 72 h. Concomitant upregulation of TNF-alpha, IL-6, ICAM-1 and the cytokine mediators NF-kB in the injured brain was observed in the injured brain after cortical contusion, and there was a highly positive relation among these variables.nnnCONCLUSIONSnCortical contusion trauma could induce a concomitant and persistent upregulation of NF-kB binding activity, TNF-alpha, IL-6 and ICAM-1 in the injured rat brain which might play a central role in the injury-induced immune response of brain.

Expression of Toll-like receptor 4 in the brain in a rabbit experimental subarachnoid haemorrhage model.

Abstract.Objective:To investigate the expression of the Toll-like receptor (TLR) 4 in the brain after experimental subarachnoid haemorrhage (SAH) in rabbits.Methods:A total of 52 rabbits were randomly divided into four groups: control group; day 3, day 5, and day 7 groups. Day 3, day 5, and day 7 groups were all SAH groups in which the rabbits were killed on day 3, 5, and 7, respectively. In SAH groups, autologous arterial blood was injected into cisterna magna twice on day 0 and day 2. Immunostaining and immunoblotting experiments were performed to detect the expression of TLR4 protein. Reverse-transcriptase polymerase chain reaction was used to analyze the presence and quantity of TLR4 mRNA.Results:The expressions of TLR4 protein and mRNA were increased remarkably in SAH groups compared with the control group. The immunohistochemical staining demonstrated high level expression of TLR4 was present mainly in the endothelial cells of capillaries in the brain.Conclusion:Our results indicate that TLR4 expression is upregulated in the brain after experimental SAH.

Glutamine decreases intestinal nuclear factor kappa B activity and pro-inflammatory cytokine expression after traumatic brain injury in rats

Abstract.Objective:To investigate whether glutamine supplementation modulates intestinal nuclear factor kappa B (NF-κB) activity and pro-inflammatory cytokine expression after traumatic brain injury (TBI) in rats.Materials and methods:Right parietal cortical contusion in male rats was made by the weight-dropping method. After trauma, the rats were randomly given chow alone or glutamine mixed chow for 5 d. Gut samples were extracted at 5 d postinjury. We measured NF-κB binding activity by electrophoretic mobility shift assay; NF-κB subunits p50 and p65 expression by immunohistochemistry; the concentrations of interleukin-1β, tumor necrosis factor-α and interleukin-6 by enzyme-linked immunosorbent assay; intestinal mucosal morphological changes by histopathological study and electron microscopy; and apoptosis by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling staining.Results:Administration of glutamine following TBI could decrease NF-κB binding activity, NF-κB p65 protein expression and concentrations of pro-inflammatory cytokines in the gut. TBI-induced damage of gut structure was ameliorated after glutamine supplementation.Conclusion:The results of the present study suggest that the therapeutic benefit of post-TBI glutamine supplementation might be due to its inhibitory effects on intestinal NF-κB activation and pro-inflammatory cytokine expression.