Hong-Xia Yin

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.

Potential contribution of nuclear factor-κB to cerebral vasospasm after experimental subarachnoid hemorrhage in rabbits

Nuclear factor-κB (NF-κB) plays a key role in inflammation, which is involved in the development of cerebral vasospasm after subarachnoid hemorrhage (SAH). In the present study, we assessed the potential role of NF-κB in regulation of cerebral vasospasm. Nuclear factor-κB DNA-binding activity was measured in cultured vascular smooth muscle cells (VSMCs) treated with hemolysate and pyrrolidine dithiocarbamate (PDTC, 80 μmol/L), an inhibitor of NF-κB. Forty-two rabbits were divided into three groups: control, SAH, and PDTC groups (n = 14 for each group). The caliber of the basilar artery was evaluated. Nuclear factor-κB DNA-binding activity and the gene expression levels of cytokines and adhesion molecules in the basilar artery were measured. Immunohistochemical study was performed to assess the expression and localization of tumor necrosis factor (TNF)-α, intercellular adhesion molecule (ICAM)-1, and myeloperoxidase (MPO). It was observed that NF-κB DNA-binding activity was significantly increased by treatment with hemolysate in cultured VSCMs, but this increase was suppressed by pretreatment with PDTC. Severe vasospasm was observed in the SAH group, which was attenuated in the PDTC group. Subarachnoid hemorrhage could induce increases of NF-κB DNA-binding activity and the gene expression levels of TNF-α, interleukin (IL)-1β, ICAM-1, and vascular cell adhesion molecule (VCAM)-1, which were reduced in the PDTC group. Immunohistochemical study demonstrated that the expression levels of TNF-α, ICAM-1, and MPO were all increased in the SAH group, but these increases were attenuated in the PDTC group. Our results suggest that NF-κB is activated in the arterial wall after SAH, which potentially leads to vasospasm development through induction of inflammatory response.

Comparison between one- and two-hemorrhage models of cerebral vasospasm in rabbits.

Injection of blood into the cisterna magna is one of the most frequently used methods to produce subarachnoid hemorrhage (SAH) models in animals. Although the two-hemorrhage model of vasospasm is frequently used in canine and rat models, most studies with rabbits only use the one-hemorrhage model. In the present study, we accomplished a side-by-side comparison between one- and two-hemorrhage models in rabbits. A total of 38 rabbits were randomly divided into three groups, i.e. control group (n = 5), one (n = 15)- and two (n = 18)-hemorrhage model groups. The degree of cerebral vasospasm, the time course of cerebral vasospasm, the clinical behavior, and the residual amount of subarachnoid blood clots were measured on days 3, 5 and 7 after the establishment of the models. Compared with one-hemorrhage model, the time course of vasospasm in the two-hemorrhage model was more coincident with that observed in humans, produced more severe vasospasm after SAH, and had an acceptable low mortality. In conclusion, the two-hemorrhage model in rabbits is more appropriate than the one-hemorrhage model for the research on SAH or cerebral vasospasm, and thus can be used for the investigation of the mechanisms of and therapeutic approaches for cerebral vasospasm.

Progesterone prevents traumatic brain injury-induced intestinal nuclear factor kappa B activation and proinflammatory cytokines expression in male rats.

We have previously shown that traumatic brain injury (TBI) can induce an upregulation of nuclear factor kappa B (NF-κB) and proinflammatory cytokines in the gut, which play an important role in the pathogenesis of acute gut mucosal injury mediated by inflammation. In this work, we investigated whether progesterone administration modulated intestinal NF-κB activity and proinflammatory cytokines expression after TBI in male rats. As a result, we found that administration of progesterone following TBI could decrease NF-κB binding activity, NF-κB p65 protein expression, and concentrations of interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α) in the gut. TBI-induced damages of gut structure were ameliorated after progesterone injections. The results of the present study suggest that the therapeutic benefit of post-TBI progesterone injections might be due to its inhibitory effects on intestinal NF-κB activation and proinflammatory cytokines expression.

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.

Expression of Toll-like receptor 4 in the basilar artery after experimental subarachnoid hemorrhage in rabbits: A preliminary study

Inflammation and immunity play a crucial role in the pathogenesis of cerebral vasospasm after subarachnoid hemorrhage (SAH). Recently, a growing body of evidence indicates that Toll-like receptor (TLR) 4 is vital for inflammation and immunity. Therefore, this study aimed to detect the expression of TLR4 in the basilar artery in a rabbit SAH model and to clarify the potential role of TLR4 in cerebral vasospasm. A total of 48 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. The animals in day 3, day 5 and day 7 groups were subjected to injection of autologous blood into cisterna magna twice on day 0 and day 2 and were killed on days 3, 5, and 7, respectively. Cross-sectional area of basilar artery was measured and the TLR4 expression was assessed by immunohistochemistry and Western blot analysis. The basilar arteries exhibited vasospasm after SAH and became more severe on day 3 and 5. The elevated expression of TLR4 was detected after SAH and peaked on day 3 and 5. TLR4 is increasingly expressed in a parallel time course to the development of cerebral vasospasm in a rabbit experimental model of SAH.

Expression of monocyte chemoattractant protein-1 in the cerebral artery after experimental subarachnoid hemorrhage

Monocyte chemoattractant protein-1 (MCP-1) is a potent chemokine that plays an important role in the recruitment of macrophages. Although previous studies have demonstrated that MCP-1 has been shown to be involved in the damaging inflammatory processes associated with stroke, infection, neoplasia, and others in the central nervous system, the role of MCP-1 in the cerebral artery after experimental subarachnoid hemorrhage (SAH) in rats has been largely unexplored. This study was undertaken to investigate the expression of the MCP-1 in SAH model and to clarify the potential role of MCP-1 in cerebral vasospasm. A total of 80 rats 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. The animals in day 3, day 5 and day 7 groups were subjected to injection of autologous blood into cisterna magna twice on day 0 and day 2 and were killed on days 3, 5, and 7, respectively. Cross-sectional area of basilar artery was measured and the MCP-1 expression was assessed by real-time PCR, Western blot and immunohistochemistry. The cross-sectional area of basilar artery was found to be 85,373+/-8794 mum(2) in control group, 59,210+/-7281 mum(2) in day 3, 50,536+/-6519 mum(2) in day 5, and 66,360+/-7452 mum(2) in day 7, respectively. The basilar arteries exhibited vasospasm after SAH and became more severe on day 5. The elevated mRNA and protein of MCP-1 were detected after SAH and peaked on day 5. MCP-1 is increasingly expressed in a parallel time course to the development of cerebral vasospasm in a rat experimental model of SAH and these findings might have important implications during the administration of specific MCP-1 antagonists in order to prevent or reduce cerebral vasospasm caused by SAH.

Inhibition of hemolysate-induced iNOS and COX-2 expression by genistein through suppression of NF-кB activation in primary astrocytes

Genistein is a major isoflavone compound from soybean. We investigated the anti-inflammatory properties of genistein in primary astrocytes treated with hemolysate. The results indicated that genistein inhibited the expression of hemolysate induced iNOS and COX-2 mRNA on astrocytes. Furthermore, this compound inhibited the level of hemolysate-stimulated nuclear factor-kappa B (NF-small ka, CyrillicB). Therefore, we suggested that the effect of genistein-mediated inhibition of the expression hemolysate-induced iNOS and COX-2 genes is due to under the suppression of NF-small ka, CyrillicB activation in the transcriptional level.

N-acetylcysteine suppresses oxidative stress in experimental rats with subarachnoid hemorrhage

The neuroprotective effect of N-acetylcysteine (NAC), a sulfhydryl-containing antioxidant, on experimentally induced subarachnoid hemorrhage (SAH) in rats was assessed. NAC was administered to rats after the induction of SAH. Neurological deficits and brain edema were investigated. The activity of antioxidant defense enzymes, copper/zinc superoxide dismutase (CuZn-SOD) and glutathione peroxidase (GSH-Px), were measured in the brain cortex by spectrophotometer. The content of the lipid peroxidation product malondialdehyde (MDA) was also analyzed. We found that NAC markedly reversed the SAH-induced neurological deficit and brain edema. We further investigated the mechanism involved in the neuroprotective effects of NAC on rat brain tissue and found that NAC significantly increased CuZn-SOD and GSH-Px activity and decreased MDA content in the SAH brain. NAC has the potential to be a novel therapeutic strategy for the treatment of SAH, and its neuroprotective effect may be partly mediated via enhancing the activity of endogenous antioxidant enzymes and inhibiting free radical generation.

Therapeutic potential of peroxisome proliferator-activated receptor gamma agonist rosiglitazone in cerebral vasospasm after a rat experimental subarachnoid hemorrhage model

The pathogenesis of cerebral vasospasm is closely associated with inflammation and immune response in arterial walls. Recently, the authors proved the key role of Toll-like receptor (TLR)4 in the development of vasospasm in experimental subarachnoid hemorrhage (SAH) model. Because peroxisome proliferator-activated receptor (PPAR) gamma agonists are identified as effective inhibitors of TLR4 activation, we investigated the anti-inflammation properties of PPAR-gamma agonist rosiglitazone in basilar arteries in a rat experimental SAH model and evaluated the effects of rosiglitazone on vasospasm. Inflammatory responses in basilar arteries were assessed by immunohistochemical staining for intercellular molecule (ICAM)-1 and myeloperoxidase (MPO). Expression of TLR4 was determined by western blot analysis. The degree of cerebral vasospasm was evaluated by measuring the mean diameter and cross-sectional area of basilar arteries. Rosiglitazone suppressed the SAH-induced inflammatory responses in basilar arteries by inhibiting the TLR4 signalling. Furthermore, rosiglitazone could attenuate cerebral vasospasm following SAH. Therefore, we suggested that PPAR-gamma agonists may be potential therapeutic agents for cerebral vasospasm.