The chemokine fractalkine in patients with severe traumatic brain injury and a mouse model of closed head injury.

The potential role of the chemokine Fractalkine (CX3CL1) in the pathophysiology of traumatic brain injury (TBI) was investigated in patients with head trauma and in mice after experimental cortical contusion. In control individuals, soluble (s)Fractalkine was present at low concentrations in cerebrospinal fluid (CSF) (12.6 to 57.3 pg/mL) but at much higher levels in serum (21,288 to 74,548 pg/mL). Elevation of sFractalkine in CSF of TBI patients was observed during the whole study period (means: 29.92 to 535.33 pg/mL), whereas serum levels remained within normal ranges (means: 3,100 to 59,159 pg/mL). Based on these differences, a possible passage of sFractalkine from blood to CSF was supported by the strong correlation between blood-brain barrier dysfunction (according to the CSF-/serum-albumin quotient) and sFractalkine concentrations in CSF (R = 0.706; P < 0.01). In the brain of mice subjected to closed head injury, neither Fractalkine protein nor mRNA were found to be augmented; however, Fractalkine receptor (CX3CR1) mRNA steadily increased peaking at 1 week postinjury (P < 0.05, one-way analysis of variance). This possibly implies the receptor to be the key factor determining the action of constitutively expressed Fractalkine. Altogether, these data suggest that the Fractalkine-CX3CR1 protein system may be involved in the inflammatory response to TBI, particularly for the accumulation of leukocytes in the injured parenchyma.     

Elevated intracranial IL-18 in humans and mice after traumatic brain injury and evidence of neuroprotective effects of IL-18-binding protein after experimental closed head injury.

Proinflammatory cytokines are important mediators of neuroinflammation after traumatic brain injury. The role of interleukin (IL)-18, a new member of the IL-1 family, in brain trauma has not been reported to date. The authors investigated the posttraumatic release of IL-18 in murine brains following experimental closed head injury (CHI) and in CSF of CHI patients. In the mouse model, intracerebral IL-18 was induced within 24 hours by ether anesthesia and sham operation. Significantly elevated levels of IL-18 were detected at 7 days after CHI and in human CSF up to 10 days after trauma. Published data imply that IL-18 may play a pathophysiological role in inflammatory CNS diseases; therefore its inhibition may ameliorate outcome after CHI. To evaluate the functional aspects of IL-18 in the injured brain, mice were injected systemically with IL-18-binding protein (IL-18BP), a specific inhibitor of IL-18, 1 hour after trauma. IL-18BP-treated mice showed a significantly improved neurological recovery by 7 days, accompanied by attenuated intracerebral IL-18 levels. This demonstrates that inhibition of IL-18 is associated with improved recovery. However, brain edema at 24 hours was not influenced by IL-18BP, suggesting that inflammatory mediators other than IL-18 induce the early detrimental effects of intracerebral inflammation.     

Interleukin-6 and its soluble receptor in serum and cerebrospinal fluid after cerebral trauma

Interleukin-6 (IL-6) and its soluble receptor (sIL-6-R) were measured in cerebrospinal fluid (CSF) and serum of 11 severely head injured patients for up to 3 weeks following trauma. IL-6 increased immediately after injury displaying much higher concentrations in CSF than in serum (n = 11). Differently, median levels of sIL-6-R remained in the normal ranges being 10 times higher in serum than in CSF. However, increased amounts over control levels were found in CSF (n = 7) and intrathecal release of sIL-6-R was also suggested (n = 7). Although no correlation with the extent of cerebral lesion or with clinical outcome was evident, elevation of sIL-6-R in CSF supports a pivotal role for IL-6/sIL-6-R complex in the injured brain.     

重型颅脑损伤患者血清和脑脊液髓鞘碱性蛋白变化及意义

探讨颅脑损伤患者血清和脑脊液（CSF）中髓鞘碱性蛋白（MBP）含量变化。方法采用酶联免疫吸附法测定了60例重型颅脑损伤患者的血清和CSF中MBP含量。结果患者血清和CSF中MBP含量均增高,其上升水平与脑损伤类型及程度有关。结论同步检测血清和CSF中MBP含量变化,对判断颅脑损伤的程度及类型有一定实用价值。     

Predictive value of serum interleukin-6 level in influenza virus-associated encephalopathy

OBJECTIVE: In Japan, >200 children with influenza virus-associated encephalopathy were reported in 1999 and the mortality rate was high. The levels of tumor necrosis factor-alpha (TNFalpha) and interleukin-6 (IL-6) in both CSF and serum were significantly increased in severe cases. The authors found a correlation between elevated serum cytokine levels and mortality and neurologic morbidity. METHODS: TNFalpha, IL-6, soluble tumor necrosis factor receptor 1 (sTNF-R1), interferon-gamma (IFNgamma), and IL-2 were measured by the ELISA method in sera from six children with encephalopathy before and during therapy, and in six age-matched controls with influenza type A virus infection. RESULTS: The increases in the serum TNFalpha, IL-6, and sTNF-R1 levels were statistically significant at the onset of symptoms before therapy, but the IL-6 level was most useful for diagnosis. The serum IL-6 levels were >6,000 pg/mL in children with brain stem dysfunction, about 150 pg/mL in children without brain stem dysfunction, and <80 pg/mL in controls. The time course of the serum IL-6 level also reflected the clinical condition. Once the serum IL-6 level was increased to >15,000 pg/mL, none of the children survived. The lower the maximal serum IL-6 level, the milder the CNS sequelae. CONCLUSION: The serum IL-6 level may be the most useful indicator for the diagnosis and the clinical severity of influenza virus-associated encephalopathy.     

Ischemic axonal injury and its recovery after focal cerebral ischemia

After focal cerebral infarction by occluding the middle cerebral artery (MCA) of the rat, the neuronal death occurred in the ipsilateral thalamic neurons, because axons of the thalamic neurons were injured by infarction and retrograde degeneration occurred in the thalamic neurons. However, cortical neurons adjacent to the infarction survived despite their axons injured by ischemia. We employed immunohistochemical staining for 200 kilodalton (kD) neurofilament (NF), in order to study those responses of cortical and thalamic neurons against axonal injury caused by focal cerebral infarction. In the sham operated rats the immunoreactivity to the anti-200 kD NF antibody was only detected in the axon but not in the cell bodies and dendrites. At 3 days after MCA occlusion, axonal swelling proximal to the site of ischemic injury was found in the caudoputamen and internal capsule of the ipsilateral side. At 7 days after occlusion, cell bodies and dendrites of the neurons in the ipsilateral cortex and thalamus were strongly stained with anti-NF antibodies. At 2 weeks after occlusion these responses disappeared in the cortex, but lasted in the thalamus. These phenomena are caused by stasis of the slow axonal transport, because the NF is transported by slow axonal transport. In the cortical neurons impairment of slow axonal transport recovered in the early phase after injury, but in the thalamic neurons the impairment prolonged up to 3 weeks after occlusion. The early recovery of axonal transport from ischemia seemed to be essential for survival of neurons after ischemic axonal injury.     

IL-10 levels in cerebrospinal fluid and serum of patients with severe traumatic brain injury: relationship to IL-6, TNF-alpha, TGF-beta1 and blood-brain barrier function

Controlling the extent of inflammatory responses following brain injury may be beneficial since posttraumatic intracranial inflammation has been associated with adverse outcome. In order to elucidate the potential role of anti-inflammatory mediators, the production of interleukin-10 (IL-10) was monitored in paired cerebrospinal fluid (CSF) and serum of 28 patients with severe traumatic brain injury (TBI) and compared to control samples. The pattern of IL-10 was analyzed with respect to the patterns of IL-6, tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-beta1 (TGF-beta1) in both fluids during a time period of up to 22 days. In parallel, the function/dysfunction of the blood-brain barrier (BBB) was monitored using the CSF-/serum-albumin quotient (Q(A)) and compared to intrathecal cytokine levels. Mean IL-10 concentration in CSF was elevated in 26 out of 28 TBI patients (range: 1.3-41.7 pg/ml) compared to controls (cut-off: 1.06 pg/ml), whereas only seven patients had elevated mean IL-10 concentration in serum (range: 5.4-23 pg/ml; cut-off: 5.14 pg/ml). The time course of IL-10 was similar in both fluids, showing a peak during the first days and a second, lower rise in the second week. Intrathecal IL-10 synthesis is hypothesized since CSF-IL-10 levels exceeded serum-IL-10 levels in most of the patients, IL-10-index (CSF/serum-IL-10/QA) was elevated in 23 individuals, and elevation of CSF-IL-10 showed to be independent from severe BBB dysfunction. Neither CSF nor serum IL-10 values correlated with the dysfunction of the BBB. IL-10, IL-6 and TGF-beta1 showed similar patterns in CSF over time, whereas rises of TNF-alpha corresponded to declines of IL-10 levels. Our results suggest that IL-10 is predominantly induced intrathecally after severe TBI where it may downregulate inflammatory events following traumatic brain damage.     

Activation of caspase-1 dependent interleukins in developmental brain trauma

Focal mechanical cortical trauma triggers diffuse apoptotic neurodegeneration in the developing rat brain which is associated with invasion of brain tissue with inflammatory mediators. We hypothesized that caspase-1 and the two caspase-1-processed cytokines, interleukin (IL)-1beta and IL-18, are involved in trauma-induced neuronal cell death in the developing brain. 7-day-old Wistar rats or C57/BL6 mice were subjected to head trauma using a weight drop device. Animals were sacrificed at defined time points following trauma and brains were processed for histology and molecular analyses. Neuronal cell death in the immature brain peaked at 12-24 h and was accompanied by a marked increase of mRNA and protein levels for caspase-1, IL-1beta and IL-18 within 2 to 12 h following the injury. Caspase-1 levels were elevated for 72 h, whereas IL-1beta decreased earlier at 48 h. IL-18 remained high over a period of 3 days and decreased to normal levels by day 7 after the injury. Intraperitoneal injection of recombinant human IL-18-binding protein (IL-18BP), a specific inhibitor of IL-18, attenuated traumatic brain injury. Mice deficient in IL-18 (IL-18-/-) were protected against trauma-induced brain damage. These findings indicate that IL-18 is involved in trauma-induced neuronal cell death in the immature rodent brain and might serve as a potential therapeutic target.     

Interleukin 1beta and interleukin 6 relationship with paediatric head trauma severity and outcome.

BACKGROUND: Based on the known inflammatory role of interleukins (IL), we evaluated IL-1beta and IL-6 expressions and their association with the severity of traumatic brain injury (TBI; Glasgow Coma Scale [GCS]) and the outcome (Glasgow Outcome Score [GOS]) recorded in a paediatric population. DESIGN: The design was a perspective observational clinical study carried out in the paediatric intensive care unit of the University Hospital. METHODS: We measured the IL-1beta and IL-6 levels in 14 children with severe TBI (patients) and in 12 children with obstructive hydrocephalus (control group). Cerebrospinal fluid (CSF) and plasma samples were collected 2 h (T1) and 24 h (T2) after TBI. Interleukins were assayed using the immunoenzymatic method. RESULTS: The IL-1beta mean level was significantly lower than the IL-6 mean level both in the CSF and plasma of TBI children. In the CSF, the IL-1beta level increased from 55.71+/-72.79 pg/ml at T1 to 106.10+/-142.12 pg/ml at T2 and the IL-6 level increased from 405.43+/-280.28 pg/ml at T1 to 631.57+/-385.35 pg/ml at T2; a similar trend was observed in plasma. We found a statistically significant correlation between the increase in CSF and plasma interleukin levels between T1 and T2 and head injury severity (GCS相似文献   

Early and specific expression of monocyte chemoattractant protein-1 in the thalamus induced by cortical injury

For many years it has been known that retrograde degeneration of thalamic neurons occurs following damage to the cerebral cortex, however, the molecular mechanisms which control this process are unknown. Recent studies have demonstrated microglial activation in thalamic nuclei well before the onset of retrograde neuronal cell death. Activated monocytes and microglia synthesize factors detrimental to neuronal survival as well as phagocytose damaged and dying neurons. Our previous studies demonstrated that monocyte chemoattractant protein-1 (MCP-1), a β chemokine which attracts cells of monocytic origin to sites of injury, is rapidly expressed in the brain following visual cortical lesions. The present study examined the expression of MCP-1 messenger RNA and protein in the thalamus following a visual cortical lesion. Aspiration lesions of visual cortex were made in adult mice. At specific times after lesion, brains were harvested and dissected into specific regions. MCP-1 message as detected using northern analysis was absent in uninjured brain, but was elevated in the ipsilateral thalamus as rapidly as 1 h following the lesion. In situ hybridization localized MCP-1 message to subpial glial cells of the lateral geniculate nucleus (LGN) of the ipsilateral thalamus after injury. ELISA showed that MCP-1 protein levels were significantly elevated in the ipsilateral thalamus at 6 h, peaked at 12 h, and remained above baseline levels for at least 1 week post lesion. In addition, anti-GFAP staining demonstrated activated astrocytes localized to the ipsilateral LGN at 24 and 72 h after injury. The early expression and regional localization of MCP-1 mRNA and protein strongly suggest that MCP-1 is a critical molecule in the regulation of thalamic retrograde neuronal degeneration.     

IL-6 promotes regeneration and functional recovery after cortical spinal tract injury by reactivating intrinsic growth program of neurons and enhancing synapse formation

Most neurons in adult mammalian central nervous system (CNS) fail to regenerate their axons after injury. Peripherally conditioned primary sensory neurons have an increased capacity to regenerate their central processes. Recent studies demonstrate that a conditioning lesion increased intrinsic growth capability is associated with the up-regulation of a group of growth-associated genes, one of the most established is interleukin-6 (IL-6). However, the cellular and molecular mechanisms by which IL-6 exerts its beneficial effect on axonal regeneration and functional recovery remain to be elucidated. The purpose of this study is to further investigate the molecular mechanisms of IL-6 in promoting regeneration and functional recovery after spinal cord injury (SCI). Here, we demonstrate that in vitro administration of IL-6 enhances neurite outgrowth of neurons on an inhibitory substrate myelin proteins, accompanied by increased expression of growth-associated genes GAP-43, SPRR1A and Arginase I. In vivo, intrathecal delivery of IL-6 for 7 days after cortical spinal tract injury induces synaptic rearrangements of sprouting axons and increases the expression of mTOR in neurons surrounding the lesion site, accompanied by improved functional recovery. In conclusion, our results show that IL-6 increases the expression of growth-associated genes and induces the expression of mTOR in lesion adjacent neurons, resulting in reactivating the intrinsic growth program of neurons to promote axonal regrowth and functional recovery after SCI.     

Mild traumatic brain injury to the infant mouse causes robust white matter axonal degeneration which precedes apoptotic death of cortical and thalamic neurons

The immature brain in the first several years of childhood is very vulnerable to trauma. Traumatic brain injury (TBI) during this critical period often leads to neuropathological and cognitive impairment. Previous experimental studies in rodent models of infant TBI were mostly concentrated on neuronal degeneration, while axonal injury and its relationship to cell death have attracted much less attention. To address this, we developed a closed controlled head injury model in infant (P7) mice and characterized the temporospatial pattern of axonal degeneration and neuronal cell death in the brain following mild injury. Using amyloid precursor protein (APP) as marker of axonal injury we found that mild head trauma causes robust axonal degeneration in the cingulum/external capsule as early as 30 min post-impact. These levels of axonal injury persisted throughout a 24 h period, but significantly declined by 48 h. During the first 24 h injured axons underwent significant and rapid pathomorphological changes. Initial small axonal swellings evolved into larger spheroids and club-like swellings indicating the early disconnection of axons. Ultrastructural analysis revealed compaction of organelles, axolemmal and cytoskeletal defects. Axonal degeneration was followed by profound apoptotic cell death in the posterior cingulate and retrosplenial cortex and anterior thalamus which peaked between 16 and 24 h post-injury. At early stages post-injury no evidence of excitotoxic neuronal death at the impact site was found. At 48 h apoptotic cell death was reduced and paralleled with the reduction in the number of APP-labeled axonal profiles. Our data suggest that early degenerative response to injury in axons of the cingulum and external capsule may cause disconnection between cortical and thalamic neurons, and lead to their delayed apoptotic death.     

Time course of IL-6 expression in experimental CNS ischemia.

Interleukin-6 (IL-6) appears to be an important modulator of the inflammatory response associated with CNS ischemia. Clinically, IL-6 values obtained in the first week post-stroke have been shown to correlate with infarct size and outcome. In this study we used a focal reversible stroke model to investigate the time course and relationship to outcome of IL-6 production in plasma, brain and CSF. Reversible middle cerebral artery occlusion or sham surgery was produced in 50 adult Swiss Webster mice by advancing an 8-0 filament into the internal carotid artery for 2 h (sham 1 min). At 3, 6, 12, 24, and 72 h (8 each ischemia; 2 each sham) groups of animals were evaluated on a 28 point clinical scale, blood and CSF obtained, and the brains were evaluated for infarct volume and IL-6 mRNA levels. Serum levels of IL-6 (ELISA mean +/- SD; undetectable in controls) overall sham group, 102 +/- 87; 3 h, 908 +/- 494* pg ml-1; 6 h, 1079 +/- 468* pg ml-1; 12 h, 980 +/- 221* pg ml-1; pg ml-1; 24 h, 320 +/- 314* pg ml-1; 72 h, 20 +/- 30* pg ml-1 (*p < or = 0.05 to sham). CSF levels (ELISA) overall sham group, 10 +/- 18; 3 h, 379 +/- 210* pg ml-1; 6 h, 157 +/- 61* pg ml-1; 12 h, 136 +/- 88* pg ml-1; 24 h, 127 +/- 99 pg ml-1; 72 h, 72 +/- 9* pg ml-1 (*p < or = 0.05 to sham). Brain IL-6 mRNA levels overall sham group, 20; 3 h, 480; 6 h, 599; 12 h, 7960; 24 h, 20267; 72 h, 0. There was an overall R2 of 0.20 between plasma and CSF IL-6. There was an overall R2 of 0.13 and 0.20 between infarct size and serum and CSF IL-6 level respectively, and an overall R2 of 0.10 and 0.17 between neurologic function and serum and CSF IL-6 level respectively. These findings confirm that IL-6 values increase following CNS ischemia with peak serum and CSF levels occurring before brain values. CSF IL-6 levels had a stronger correlation with neurologic function and infarct size than serum.     

Increase of interleukin-1β mRNA and protein in the spinal cord following experimental traumatic injury in the rat

Interleukin-1 beta (IL-1β) is a major mediator of inflammation and a growth promoter for many cell types that could play an important role in the consequences of traumatic spinal cord injury (SCI). In the present study, the expression of IL-1β and its mRNA was determined in the rat spinal cord following a standardized contusion injury. IL-1β mRNA, measured with quantitative RT-PCR, was significantly increased in the lesion site by 1 h after SCI (35.2±5.9 vs. 9.1±2.1 pg/mg RNA, n=3, P<0.05) and remained significantly higher than in the normal spinal cord for at least 72 h post-injury (p.i.). IL-1β mRNA levels in tissue immediately caudal to the lesion site did not change after the injury. IL-1β protein levels, measured by an ELISA, were determined at the lesion site and in cerebrospinal fluid (CSF) and serum samples. IL-1β levels in the CSF and serum were much lower than in the spinal cord. At the lesion site, IL-1β was increased significantly by 1 h p.i., peaked at 8 h (32.3±0.1 vs. 7.6±1.9, ng/g tissue, n=5, P<0.05) and remained significantly higher than normal through at least 7 days p.i. These results suggest that the increased IL-1β mRNA and protein levels are an early and local response at the lesion site that could trigger other, later, responses to traumatic SCI.     

Cerebrospinal fluid interleukin-6 levels in patients with West syndrome

Elevated cytokine response has been reported in patients with epileptic seizures. The objective of this study was to investigate the possible role of interleukin-6 (IL-6) in the pathogenesis of infantile spasms in West syndrome (WS). We measured IL-6 levels in cerebrospinal fluid (CSF) obtained from the newly diagnosed patients with WS. Twelve patients with WS (Group I) were classified as symptomatic WS (Group IA) in eight and as cryptogenic WS (Group IB) in four. The results were compared with control groups including patients with tonic-clonic seizures associated with two different kind of inflammation of central nervous system; Group IIA (infection): bacterial meningitis/encephalitis and Group IIB (trauma): post-traumatic seizures. There was no statistically significant difference between the mean values of CSF IL-6 levels in patients with WS (2.95 +/- 2.31 pg/ml) and those of subgroups of WS (Group IA: 2.26 +/- 2.01 pg/ml and Group IB: 4.33 +/- 2.52 pg/ml). Both control groups had highly increased IL-6 levels in CSF (Group IIA: 193.05 +/- 185.52 pg/ml and Group IIB: 112.74 +/- 167.44 pg/ml) than those of the patients with WS. Elevated IL-6 response in patients with tonic-clonic seizures associated with inflammation of central nervous system might be due to the seizures themselves or related to the underling etiology (infection or trauma). However, no elevated IL-6 response was found in patients with infantile spasms.     

High-sensitivity C-reactive protein levels in cerebrospinal fluid and serum in severe head injury: Relationship to tumor necrosis factor-α and interleukin-6

Recent studies have demonstrated the role of high-sensitivity C-reactive protein (hsCRP) in inflammatory diseases; however, it is unclear whether this molecule has a role after severe head injury (SHI). Our aim was to evaluate the levels of hsCRP in both cerebrospinal fluid (CSF) and serum from patients after SHI. The study focused on 11 patients with SHI, and evaluated CSF and serum levels of hsCRP, tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in a 10-day period following the head trauma. The values were compared with those from nine control patients, who had normal pressure hydrocephalus. In the CSF and serum of the patients after SHI, HsCRP was found to be significantly higher, at all times, than in the controls; TNF-α and IL-6 levels were also higher in these patients. However, hsCRP levels did not correlate with either TNF-α or IL-6. TNF-α and IL-6 increased during the period immediately following the SHI, and intrathecal levels were always higher than those of the serum. This study demonstrates for the first time that hsCRP reaches high levels in both CSF and serum in patients with SHI, and it may therefore be used as an inflammatory index. This finding suggests a need for further studies in this area, which are larger in scope than the present study.     

卒中后抑郁与炎症因子的关系研究

目的分析卒中后抑郁(post-stroke depression,PSD)大鼠血清IL-17A水平、海马IL-1β、TNF-α mRNA表达的变化,探讨PSD的病理生理机制。方法将30只成年的无特定病原体级SD雄性大鼠随机分为假手术组、卒中组、PSD组,对各组大鼠进行基线行为学评估,其中卒中组和PSD组大鼠行大脑中动脉闭塞(middle cerebral artery occlusion,MCAO)缺血再灌注处理,1周后对PSD组大鼠行慢性轻度刺激(chronic unpredictable mild stress,CUMS),每天给予1~2种刺激,连续4周,CUMS刺激4周后对各组大鼠进行行为学评估。评估结束后采用尼氏染色观察各组大鼠海马区神经元形态,使用ELISA方法检测大鼠血清中IL-17A水平,实时荧光定量PCR检测大鼠海马IL-1β、TNF-α mRNA表达。观察PSD情况下,血清及海马神经元炎症因子的表达水平及海马损伤情况。结果假手术组、卒中组和PSD组大鼠血清的IL-17A水平分别为18.56±2.56 pg/mL、40.78±4.13 pg/mL和52.10±5.22 pg/mL,三组比较差异有统计学意义;假手术组、卒中组、PSD组大鼠海马区IL-1βmRNA相对表达水平分别为0.570±0.322、2.617±0.128和3.189±0.107,三组比较差异有统计学意义;假手术组、卒中组、PSD组大鼠海马区TNF-α mRNA基因相对表达水平分别为0.999±0.007、1.258±0.042和1.623±0.041,三组比较差异有统计学意义;尼氏染色提示卒中组、PSD组海马区CA1区神经元存在损伤,以PSD组最明显。结论 PSD组大鼠血清IL-17A水平上调,海马IL-1β、TNF-αmRNA高表达,提示PSD发生的病理生理机制中可能有炎症反应参与。