Persistent accumulation of cyclooxygenase-1-expressing microglial cells and macrophages and transient upregulation by endothelium in human brain injury

OBJECT: Secondary damage after central nervous system (CNS) injury is driven in part by oxidative stress and CNS inflammation and is substantially mediated by cyclooxygenases (COXs). To date, the rapidly inducible COX-2 isoform has been primarily linked to inflammatory processes, whereas expression of COX-1 is confined to physiological functions. The authors report the differential localization of COX-1 in human traumatic brain injury (TBI). METHODS: Differential cellular COX-1 protein expression profiles were analyzed following TBI in 31 patients and compared with neuropathologically unaltered control brains by using immunohistochemistry. In these patients with TBI, a significant increase of COX-1 protein expression by vessel endothelial and smooth-muscle cells and CD68+ microglia/macrophages was observed to be strictly confined to the lesion. Accumulation of COX-1+ microglia/macrophages in the lesion was already evident 6 hours postinjury, reaching maximal levels after several weeks and remaining elevated at submaximal levels for several months after injury. Furthermore, COX-1+ cell clusters were located in the Virchow-Robin space during the leukocyte infiltration period from Days 4 to 8 after TBI. Double-labeling experiments confirmed coexpression of COX-1 by CD68+ microglia/macrophages. The numbers of COX-1+ vessel endothelial and smooth-muscle cells increased from Day 1, remaining at submaximal levels for months after injury. CONCLUSIONS: The prolonged accumulation of COX- 1+ microglia/macrophages that were restricted to perilesional areas affected by the acute inflammatory response points to a role of COX-1 in secondary injury. The authors have identified localized, accumulated COX- I expression as a potential pharmacological target following TBI. Their results challenge the current paradigms of a selective COX-2 role in the postinjury inflammatory response.     

Interleukin-6 and nerve growth factor upregulation correlates with improved outcome in children with severe traumatic brain injury

Secondary brain damage after traumatic brain injury (TBI) involves neuro-inflammatory mechanisms that are mainly dependent on the intracerebral production of cytokines. Interleukin-6 (IL-6) may have a role both in the pathogenesis of neuronal damage and in the recovery mechanisms of injured neurons through the modulation of nerve growth factor (NGF) biosynthesis. However, the relationship between IL-6 and NGF expression and the severity and outcome of TBI remains controversial. We have conducted a prospective observational clinical study to determine whether the concentration of IL-6 and NGF in the cerebrospinal fluid (CSF) of children with TBI correlates with the severity of the injury and neurologic outcome of patients. CSF samples were collected from 29 children at 2 h (time T1) and 48 h (time T2) after severe TBI, and from 31 matched controls. TBI severity was evaluated by Glasgow Coma Scale (GCS) and neurologic outcome by Glasgow Outcome Score (GOS). CSF concentrations of IL-6 and NGF were measured by immunoenzymatic assays. Early NGF concentrations (T1) correlated significantly with head injury severity, whereas no correlation was found between GCS and IL-6. Furthermore, IL-6 and NGF upregulation after injury was associated with better neurologic outcomes. Based on these findings, we posit that NGF expression is a useful marker of brain damage following severe TBI. Moreover, the early upregulation of both IL-6 and NGF, which correlates with a favorable neurologic outcome, may reflect an endogenous attempt at neuroprotection in response to the damaging biochemical and molecular cascades triggered by traumatic insult.     

Molecular mechanisms underlying effects of neural stem cells against traumatic axonal injury

Transplantation of neural stem cells (NSCs) improves functional outcomes following traumatic brain injury (TBI). Previously we demonstrated that human NSCs (hNSCs) via releasing glial cell line-derived neurotrophic factor (GDNF), preserved cognitive function in rats following parasagittal fluid percussion. However, the underlying mechanisms remain elusive. In this study, we report that NSC grafts significantly reduce TBI-induced axonal injury in the fimbria and other brain regions by blocking abnormal accumulation of amyloid precursor protein (APP). A preliminary mass spectrometry proteomics study revealed the opposite effects of TBI and NSCs on many of the cytoskeletal proteins in the CA3 region of the hippocampus, including α-smooth muscle actin (α-SMA), the main stress fiber component. Further, Western blot and immunostaining studies confirmed that TBI significantly increased the expression of α-SMA in hippocampal neurons, whereas NSC grafts counteracted the effect of TBI. In an in vitro model, rapid stretch injury significantly shortened lengths of axons and dendrites, increased the expression of both APP and α-SMA, and induced actin aggregation, effects offset by GDNF treatment. These GDNF protective effects were reversed by a GDNF-neutralizing antibody or a specific calcineurin inhibitor, and were mimicked by a specific Rho inhibitor. In summary, we demonstrate for the first time that hNSC grafts and treatment with GDNF acutely reduce traumatic axonal injury and promote neurite outgrowth. Possible mechanisms underlying GDNF-mediated neurite protection include balancing the activity of calcineurin, whereas GDNF-induced neurite outgrowth may result from the reduction of the abnormal α-SMA expression and actin aggregation via blocking Rho signals. Our study also suggests the necessity of further exploring the roles of α-SMA in the central nervous system (CNS), which may lead to a new avenue to facilitate recovery after TBI and other injuries.     

Case study: Cases of two patients whose food aversions disappeared following severe traumatic brain injury

Following traumatic brain injury TBI the complete disappearance of food aversions was observed in the cases of two patients. In one of the cases, a young female, this change in her food aversion was manifested several months after the TBI, from the time when she was able to eat normally. The other patient, a young man, exhibited the disappearance of his food aversion immediately after recovery from his unconscious state following TBI. These results indicate that the disappearance of food aversions was a consequence of TBI.     

Minocycline reduces traumatic brain injury-mediated caspase-1 activation, tissue damage, and neurological dysfunction

OBJECTIVE: Caspase-1 plays an important functional role mediating neuronal cell death and dysfunction after experimental traumatic brain injury (TBI) in mice. Minocycline, a derivative of the antibiotic tetracycline, inhibits caspase-1 expression. This study investigates whether minocycline can ameliorate TBI-mediated injury in mice. METHODS: Brains from mice subjected to traumatic brain injury underwent immunohistochemical analyses for caspase-1, caspase-3, and a neuronal specific marker (NeuN). Minocycline- and saline-treated mice subjected to traumatic brain injury were compared with respect to neurological function, lesion volume, and interleukin-1beta production. RESULTS: Immunohistochemical analysis revealed that activated caspase-1 and caspase-3 are present in neurons 24 hours after TBI. Intraperitoneal administration of minocycline 12 hours before or 30 minutes after TBI in mice resulted in improved neurological function when compared with mice given saline control, as assessed by Rotarod performance 1 to 4 days after TBI. The lesion volume, assessed 4 days after trauma, was significantly decreased in mice treated with minocycline before or after trauma when compared with saline-treated mice. Caspase-1 activity, quantified by measuring mature interleukin-1beta production by enzyme-linked immunosorbent assay, was considerably increased in mice that underwent TBI, and this increase was significantly diminished in minocycline-treated mice. CONCLUSION: We show for the first time that caspase-1 and caspase-3 activities localize specifically within neurons after experimental brain trauma. Further, these results indicate that minocycline is an effective pharmacological agent for reducing tissue injury and neurological deficits that result from experimental TBI, likely through a caspase-1-dependent mechanism. These results provide an experimental rationale for the evaluation of minocycline in human trauma patients.     

VEGF and VEGF receptor expression after experimental brain contusion in rat

Angiogenesis following traumatic brain injury (TBI) may be of importance not only for post-traumatic reparative processes but also for the development of secondary injuries. Vascular endothelial growth factor (VEGF) is a major regulator of endothelial cell proliferation, angiogenesis, and vascular permeability, though its possible involvement in secondary injuries after TBI is largely unknown. This study was undertaken to analyze the expression of VEGF and the VEGF receptors in experimental brain contusion in rat. Twenty-three adult female Sprague-Dawley rats were subjected to a focal cerebral contusion injury by use of a weight-drop model. Four additional rats underwent craniotomy only. The animals were sacrificed 6 h, or 1, 2, 4, 6, 8, or 16 days post-injury. Expression of VEGF and the VEGF receptors VEGFR1 (Flt-1) and VEGFR2 (Flk-1) were studied by in situ hybridization and immunohistochemistry. VEGF messenger (m)RNA and protein expression were detected in astrocytes, neutrophils, and macrophages in or adjacent to the injury from 1 day after injury, with a peak expression after 4-6 days. Flt-1 and Flk-1 mRNA and protein were detected in vessels adjacent to the lesion from 1 day after injury throughout day 6 after injury. It was also noted that Flt-1/Flk-1 and VEGF-positive vessels often were negative for SMI-71, a marker for vessels in areas with blood-brain barrier (BBB). In conclusion, we have demonstrated that TBI leads to an upregulation of VEGF, Flt-1, and Flk-1 mRNA and protein in and around the lesion. The data provide a foundation for future pharmacological intervention studies focusing on posttraumatic angiogenesis and possible injury repair effects of the VEGF system in TBI.     

Guidelines for the pharmacologic treatment of neurobehavioral sequelae of traumatic brain injury

There is currently a lack of evidence-based guidelines to guide the pharmacological treatment of neurobehavioral problems that commonly occur after traumatic brain injury (TBI). It was our objective to review the current literature on the pharmacological treatment of neurobehavioral problems after traumatic brain injury in three key areas: aggression, cognitive disorders, and affective disorders/anxiety/ psychosis. Three panels of leading researchers in the field of brain injury were formed to review the current literature on pharmacological treatment for TBI sequelae in the topic areas of affective/anxiety/ psychotic disorders, cognitive disorders, and aggression. A comprehensive Medline literature search was performed by each group to establish the groups of pertinent articles. Additional articles were obtained from bibliography searches of the primary articles. Group members then independently reviewed the articles and established a consensus rating. Despite reviewing a significant number of studies on drug treatment of neurobehavioral sequelae after TBI, the quality of evidence did not support any treatment standards and few guidelines due to a number of recurrent methodological problems. Guidelines were established for the use of methylphenidate in the treatment of deficits in attention and speed of information processing, as well as for the use of beta-blockers for the treatment of aggression following TBI. Options were recommended in the treatment of depression, bipolar disorder/mania, psychosis, aggression, general cognitive functions, and deficits in attention, speed of processing, and memory after TBI. The evidence-based guidelines and options established by this working group may help to guide the pharmacological treatment of the person experiencing neurobehavioral sequelae following TBI. There is a clear need for well-designed randomized controlled trials in the treatment of these common problems after TBI in order to establish definitive treatment standards for this patient population.     

Neurochemical alterations and current pharmacological strategies in the treatment of traumatic brain injury

Summary In recent years, our knowledge concerning pathophysiological changes in brain metabolism after traumatic brain injury (TBI) has greatly expanded. This, in turn, has enabled the development of specific pharmacological strategies for the supplementary treatment of brain-injured patients with the aim of reducing secondary brain damage. The present article focuses on the pathophysiology of TBI and the possibilities for pharmacological intervention. While some of the substances reviewed are presently used in the treatment of TBI, others are under experimental and clinical evaluation at different stages.      

Is there a role for vagus nerve stimulation therapy as a treatment of traumatic brain injury?

This paper aims to review the current literature on vagus nerve stimulation (VNS) use in animal models of traumatic brain injury (TBI) and explore its potential role in treatment of human TBI. A MEDLINE search yielded four primary papers from the same group that demonstrated VNS mediated improvement following fluid percussion models of TBI in rats, seen as motor and cognitive improvements, reduction of cortical oedema and neuroprotective effects. The underlying mechanisms are elusive and authors attribute these to attenuation of post traumatic seizures, a noradrenergic mechanism and as yet undetermined mechanisms. Reviewing and elaborating on these ideas, we speculate other potential mechanisms including attenuation of peri-infarct depolarisations, attenuation of glutamate mediated excitotoxicity, stabilisation of intracranial pressure, enhancement of synaptic plasticity, upregulation of endogenous neurogenesis and anti-inflammatory effects may have a role. Although this data unequivocally shows that VNS improves outcome from TBI in animal models, it remains to be determined if these findings translate clinically. Further studies are warranted.     

Cerebral apoptosis in severe traumatic brain injury patients: an in vitro, in vivo, and postmortem study

One of the most important recent observations in traumatic brain injury (TBI) relates to the potential role of apoptosis in secondary brain injury. We aimed to analyze the presence of apoptosis and the expression of apoptosis-related proteins in brain samples from patients with TBI. We also tried to find any association between the in situ results and the in vitro observations in a neuronal model of induced-apoptosis. Brain tissue from the pericontusional zone (PCZ) of patients with traumatic contusions and from post-mortem samples was analyzed. Immunohistochemical analyses of apoptosis-related proteins and the terminal deoxynucleotide transferase-mediated nick end labeling (TUNEL) method to determine the presence of apoptotic cells were performed. Apoptotic rates on neuronal cells induced by jugular bulb vein sera was determined by flow cytometry. TUNEL-positive cells were detected in all PCZ of traumatic contusions and in most of PCZ in post-mortem specimens (none in control; p = 0.026). In vivo samples showed higher expression of antiapoptotic proteins Bcl-2 (p = 0.027) and Bcl-XL (p = 0.014) than post-mortem samples. In autopsies, the expression of Fas and Bim (p < 0.05) were higher in PCZ than in the zone distal from the contusion. In vitro studies showed that apoptotic rate was an independent factor associated with mortality at 6 months (p = 0.014). In the receiving operator curve (ROC) curve, a cut-off point of 66.5% showed a sensitivity of 89.5% and specificity of 66.7% in the prediction of patients' death. Cerebral apoptosis is a prominent form of cell death in the PCZ of human traumatic cerebral contusions, and high rates of in vitro apoptosis are associated with a poorer prognosis after TBI.     

不同降温方式对脑外伤后伤灶区c-fos mRNA和神经生长因子表达的影响

目的 通过对大鼠重型脑挫裂伤后体温的干预,观察不同降温方式对脑外伤后伤灶区c-fos mRNA和神经生长因子(nerve growth factor,NGF)表达的影响,了解其表达强度是否与伤后不同降温方式对脑损伤的保护机制有关. 方法 健康成年SD大鼠336只,随机分为四组(每组84只),除假手术组外各组动物均按自由落体法造成重度脑挫裂伤;每组又按处死时间分为七个亚组(每亚组12只),分别检测c-fos mRNA(6只)与NGF(6只)的表达. 结果 ①伤后4h、8h、12 h与24h,全身亚低温组与局部亚低温组c-fos mRNA表达明显高于TBI组(P＜0.01),其他各时点无差异;TBI组在伤后4h、8h、12 h、24h与3d,c-fos mRNA表达均明显高于假手术组(P＜0.01).②伤后4h、8h,全身亚低温组与局部亚低温组NGF表达与TBI组无明显差异(P＞0.05);而在伤后12 h、24h、3d、5d与7d,两亚低温组NGF表达明显高于TBI组((P＜0.05或P＜0.01).③全身亚低温组与局部亚低温组在伤后各时间点c-fos mRNA和NGF表达无显著性差异(P＞0.05). 结论 脑外伤后亚低温可促进c-fos mRNA和NGF表达上调,全身亚低温与局部亚低温两种不同降温方式无明显差异.     

神经激肽1受体拮抗剂对大鼠创伤性脑损伤的影响

目的 研究大鼠创伤性脑损伤(Traumatic brain injury,TBI)后血P物质(Substance P,SP)的表达和神经激肽1受体拮抗剂对TBI的作用,探讨抑制神经源性炎症反应对创伤性脑损伤的影响.方法 建立大鼠自由落体创伤模型,药物组于创伤后立即尾静脉给予n-乙酰左旋色氨酸(n-acetyl-L-tryptophan,NAT)(25 μmol/kg).大鼠TBI后30分钟和6小时利用酶联免疫吸附法检测血SP的含量,TBI后24小时采用rotarod试验评估大鼠神经行为功能及干湿称重法检测脑组织含水量.结果 大鼠TBI后30分钟时血SP浓度出现明显升高(P＜0.01),6小时时血SP浓度降低.大鼠TBI后24小时脑组织含水量明显升高,其神经行为功能下降,NAT可减少TBI后24h脑组织含水量并改善神经功能损伤(P＜0.05).结论 大鼠TBI早期血SP浓度增高,NAT通过抑制神经源性炎症可减轻脑水肿及神经功能损伤.     

Disturbances in affective communication following brain injury

PRIMARY OBJECTIVE: Disturbances in affect expression and perception are often clinically observed in brain injured patients during the acute stages of recovery. This study examined whether such disturbances are related to the acute nature of the injury or specific type of injury in patients with stroke (CVA) versus traumatic brain injury (TBI). RESEARCH DESIGN: Retrospective cohort of patients seen for inpatient rehabilitation following brain injury. PROCEDURES: Participants were 27 CVA and 27 TBI patients. Their performance was compared to 27 normal controls on the BNI Screen for Higher Cerebral Functions. OUTCOMES AND RESULTS: While both patient groups performed significantly worse than the control group on affect expression, perception and spontaneity (p<0.01), the CVA group performed significantly worse than the TBI group (p<0.01) on affect perception. Results of this study document disturbances in affect in brain injured patients and highlight the importance of assessing affect during early recovery.     

异丙酚对大鼠创伤性脑损伤时DAPK mRNA表达的影响

目的 探讨异丙酚对大鼠创伤性脑损伤(TBI)时死亡相关蛋白激酶(DAPK)mRNA表达的影响.方法 雄性Wistar大鼠60只,月龄3～4月,体重250～300 g,随机分为6组(n=10):正常对照组(C组)、假手术组(S组)、TVI组、生理盐水组(NS组)、脂肪乳剂组(FE组)及异丙酚组(P组).采用自由落体撞击法建立大鼠创伤性脑损伤模型,于制备模型成功后以2 ml·kg-1·h-1的速率经尾静脉分别输注生理盐水、10%脂肪乳剂、1%异丙酚4 h.于模型制备成功后24 h断头处死大鼠取脑,采用细胞原位末端标记(TUNEL)法计数凋亡神经元,计算神经元凋亡率;采用RT-PCR法检测DAPK mRNA的表达水平.结果 与C组和S组比较,TBI组模型制备成功后24 h时损伤区及损伤边缘区神经元DAPK mRNA表达上调,神经元凋亡率升高(P<0.05);P组DAPK mRNA表达水平及神经元凋亡率较TBI组、NS组和FE组降低(P<0.05).结论 异丙酚可能通过抑制DAPK mRNA表达上调减少脑神经元凋亡,从而在一定程度上减轻大鼠创伤性脑损伤.     

Neuronal apoptosis inhibitory protein expression after traumatic brain injury in the mouse.

Apoptosis of brain cells is triggered by traumatic brain injury (TBI) and is blocked by caspase inhibitors. The neuronal apoptosis inhibitor protein (NAIP), which has been shown to inhibit apoptosis by both caspase-dependant and caspase-independent mechanisms, is neuroprotective in rat models of cerebral ischemia and axotomy. In order to gain a better appreciation of CNS apoptosis following head injury in general and the possible involvement of NAIP specifically, we have configured a mouse model of TBI. In addition to demonstrating apoptosis, the spatiotemporal expression or levels of a number of proteins with apoptosis modulating effects have been determined. Apoptosis of neurons and oligodendrocytes following TBI was observed in brain sections which were triple-stained with in situ end labeling, bisbenzimide and immunofluorescent stain for neuron specific nuclear protein and myelin-associated glycoprotein, respectively. Further evidence for apoptosis following TBI in this model was obtained in brain samples using ligation-mediated PCR amplification of DNA fragments and gel electrophoresis. The temporal profile of apoptosis was similar to the temporal profile of microglial activation determined by CD11b staining and TNFa expression induced by TBI. NAIP staining in sections of cerebral cortex and subcortical white matter increased at 6 h and decreased towards control levels at 24 h post-TBI. Temporal changes in the expression of NAIP were also observed using Western blot analysis of brain samples removed from injured cortex and sub-cortical white matter. At the time that NAIP expression decreased markedly (24 h post-TBI), procaspase-3 levels also decreased, PARP cleavage increased, and the highest levels of apoptosis were observed. These findings have implications in our understanding of traumatically induced programmed cell death and may be useful in the configuration of therapies for this common injury state.     

Rapid and widespread microglial activation induced by traumatic brain injury in rat brain slices

In order to assess the role of circulating blood in early microglial activation after traumatic brain injury (TBI), controlled cortical impact injury was applied to adult rat brain slices (400 microm in thickness) and the microglial response was examined. The complement receptor (CR3) expression and morphological transformation of the microglia were evaluated by OX42 immunohistochemistry. At 5 min following injury, activated microglia with intense CR3 expression appeared throughout the hemisphere on the injured side. In contrast, the morphology and CR3 expression of the microglia on the contralateral side were indistinguishable from those of the resident ramified microglia seen in normal brains. At 30 min following injury, microglial activation was more pronounced on the injured side, while the microglia on the contralateral side still retained a ramified morphology. These results are consistent with our previous observations made in in vivo experiments, which indicate that, as the brain slice paradigm excludes variables arising from the circulating blood, the rapid and widespread microglial activation observed following TBI can not be attributed exclusively to the infiltration of blood-borne macrophages or molecules. Rather this activation is most likely caused by intrinsic mechanisms within the brain tissue, such as traumatic depolarization.     

Age-associated mitochondrial DNA deletions are not evident chronically after experimental brain injury in the rat

The enduring cognitive and sensorimotor deficits that result from traumatic brain injury (TBI) are associated with metabolic stress and free radical cascades, which establish conditions that may promote mitochondrial DNA (mtDNA) deletion and oxidation, often observed as a consequence of normal aging. Without substantial mtDNA repair mechanisms, permanent alterations to essential mitochondrial enzymes could perpetuate post-injury pathologic cascades. To determine whether mitochondria from the injured cortex and hippocampus sustain mtDNA damage after TBI, we evaluated mtDNA deletion and oxidation following lateral fluid percussion TBI in the anesthetized adult Sprague-Dawley rat (4 months) compared with uninjured adult and aged rats (n = 4/group). The presence of the 4.8-KB common deletion in mtDNA was assessed by conventional PCR to generate products representing total, non-deleted wild-type, and deleted mtDNA in homogenized tissue and isolated mitochondria 3 and 14 days following TBI. Total and wild-type mtDNA amplification products were obtained from cortical and hippocampal tissue and mitochondria for all conditions. Although no mtDNA deletions were observed following experimental TBI, mtDNA deletion was detected in cortical tissue, but not isolated mitochondria, of naive, aged (24 months) Sprague-Dawley rats, suggesting that the isolation protocol may exclude mitochondria harboring mtDNA damage. Oxidative mtDNA damage in isolated mitochondria assayed by ELISA for 8-hydroxy-2'-deoxyguanosine (8-OHdG) from cortical (0.50 +/- 0.08 pg 8-OHdG/ micro g mitochondria) and hippocampal (0.35 +/- 0.02) regions were unaffected by TBI. However, mitochondrial protein yields from injured and aged brains were comparable and significantly lower than uninjured brain, suggesting that the underlying pathology between TBI and aging may be similar.     

Effect of decompressive craniectomy on aquaporin-4 expression after lateral fluid percussion injury in rats

Decompressive craniectomy is one therapeutic option for severe traumatic brain injury (TBI), and it has long been used for the treatment of patients with malignant post-traumatic brain edema. A lack of definitive evidence, however, prevents physicians from drawing any conclusions about the effects of decompressive craniectomy for the treatment of TBI. Therefore, the aim of the present study was to investigate the influence of decompressive craniectomy on post-traumatic brain edema formation. The aquaporin-4 (AQP4) water channel is predominantly expressed in astrocytes, and it plays an important role in the regulation of brain water homeostasis. In the present study, we investigated the time course of AQP4 expression and the water content of traumatized cortex following decompressive craniectomy after TBI. Adult male Sprague-Dawley rats (300-400?g) were subjected to lateral fluid percussion injury using the Dragonfly device. The effect of decompressive craniectomy was studied in traumatized rats without craniectomy (closed skull, DC-), and in rats craniectomized immediately after trauma (DC+). AQP4 expression was investigated with a Western blot analysis and immunohistochemistry. Brain edema was measured using the wet weight/dry weight method. At 48?h after TBI, AQP4 expression of the DC- group was significantly increased compared with the DC+ group (p?相似文献