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Query: UNIPROT:P05231 (interleukin-6)
 23,907 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of transient global ischemia using bilateral carotid artery occlusion on regional cytokine levels in gerbil brain were investigated using enzyme-linked immunoassay techniques. Brain concentrations of interleukin-6 (IL-6), interleukin-1 beta (IL-1 beta), and tumor necrosis factor-alpha (TNF-alpha) were increased during the early recirculation period ( < 6 h) after 10 min of ischemia, with lesser degrees of elevation following only 5 min of ischemia. TNF-alpha levels in the hippocampus and striatum were significantly increased as early as 1 h after recirculation, declining sharply to control levels by 12 h, then transiently increasing at 24 h. Elevated levels of IL-1 beta and IL-6 were not seen until 3-6 h post-occlusion. No significant increases in cytokine concentrations were observed in the cerebellum or thalamus. These results suggest that regionally selective increases in cytokines may be involved in the pathophysiological changes in hippocampus and striatum following transient cerebral ischemia.
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PMID:Early increases in TNF-alpha, IL-6 and IL-1 beta levels following transient cerebral ischemia in gerbil brain. 871 Jan 73

During cerebral ischemia, the expression of interleukin-6 (IL-6), which has neuroprotective properties, increases. To understand the underlying mechanism, the regulation of IL-6 expression by neurotransmitters that accumulate during cerebral ischemia was investigated. Adenosine stimulated IL-6 secretion in primary astrocytes four- to 10-fold. The effect was concentration dependent, the EC50 being approximately 8 microM. Although the nonselective analogue 2-chloroadenosine (2CA) increased IL-6 secretion to a similar extent, the A1-selective agonist N6-cyclopentyladenosine or the A2a agonist CGS-21680 had only a marginal effect on IL-6 secretion. IL-6 secretion stimulated by 2CA (10 microM) was inhibited by the nonselective adenosine antagonist 8-(p-sulfophenyl)theophylline, whereas the A1-selective antagonist 8-cyclopentyl-1,3-dipropylxanthine or the A2a-selective antagonist 8-(3-chlorostyryl)caffeine had no effect, to a concentration of 0.1 microM. Transcription of the IL-6 gene was investigated by transfecting primary astrocytes with a reporter fusion gene containing the human IL-6 promoter (-179/+12). 2CA stimulated IL-6 gene transcription 2.5-fold. Mutations of the binding site for NF-kappaB or NF-IL6 abrogated the response to 2CA. Thus, an increase of extracellular adenosine during focal cerebral ischemia may stimulate IL-6 expression via A2b receptors. The induction of IL-6 expression appears to involve a transcriptional effect that depends on NF-kappaB and NF-IL6.
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PMID:Stimulation of interleukin-6 secretion and gene transcription in primary astrocytes by adenosine. 928 37

Interleukin-6 (IL-6) is a neurotrophic cytokine expressed in both neurons and glia. The present study shows that cerebral ischemia produced by permanent occlusion of the middle cerebral artery (MCAO) produces a dramatic increase in IL-6 bioactivity in the ischemic hemisphere within 2 hours of MCAO (167 +/- 55 IU versus sham: 50 +/- 35 IU), with further increases at 8 hours (3,456 +/- 1,162 IU) and 24 hours (6,088 +/- 1,772 IU). In a separate series of experiments, intracerebroventricular injection of recombinant IL-6 (3,100 or 31,000 IU) significantly reduced ischemic brain damage after MCAO (to 52% and 65% of controls, respectively). The large increase in endogenous IL-6 bioactivity in response to ischemia, together with the marked neuroprotection produced by exogenous IL-6 suggest that this cytokine is an important endogenous inhibitor of neuronal death during cerebral ischemia.
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PMID:Cerebral interleukin-6 is neuroprotective during permanent focal cerebral ischemia in the rat. 946 60

Markedly increased interleukin-6 (IL-6) mRNA levels occur in experimental cerebral ischemia, although the protein production and cellular sources of IL-6 remain unclear. We examined the cellular localization of IL-6 protein in gerbil brain following transient forebrain ischemia employing immunohistochemistry and Western blot analysis. The ischemia/recirculation groups revealed distinct IL-6 immunoreactivity predominantly in cortical and hippocampal neurons after 3 hours to 3 days recirculation. At 12 h recirculation, the IL-6 expression declined specifically in the hippocampus CA1. Microglia, but not activated astrocytes, also expressed IL-6 immunoreactivity. The sham group showed no apparent immunoreactivity. IL-6 protein may thus be expressed mainly in neurons following transient forebrain ischemia. Its transient decline in the CA1 at 12 h recirculation could reflect the specific vulnerability of this region.
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PMID:Cerebral neurons express interleukin-6 after transient forebrain ischemia in gerbils. 1020 45

Although interleukin-6 (IL-6) has various neuroprotective effects against cerebral ischemia, the topographic distribution and cellular source of IL-6 after cerebral ischemia remain unclear. In the current study, the localization of IL-6 protein was immunohistochemically examined in rats after 3.5, 12, 24, and 48 hours of reperfusion after 1.5 hours of middle cerebral artery occlusion. Middle cerebral artery occlusion was induced by the intraluminal suture method. The specificity of the anti-IL-6 antibody used in the current study was confirmed by Western blot analysis and an immunoabsorption test. To identify the cellular source, lectin histochemical study and immunohistochemical study with microtubule-associated protein-2, ED1, and glial fibrillary acidic protein also were carried out. The sham group did not show any clear IL-6 immunoreactivity. After 3.5 hours of reperfusion, IL-6 immunoreactivity was first detected on the reperfused side, and it was upregulated, especially in the periinfarct region, after 24 hours of reperfusion. Also, IL-6 was expressed after 3.5 hours of reperfusion in the contralateral cerebral cortex and bilateral hippocampi. Double staining showed that the cells containing IL-6 were neurons and round-type microglia, not astrocytes. The current findings suggest that IL-6 expression in ischemically threatened neurons and reactive microglia is closely associated with brain tissue neuroprotective mechanisms against cerebral ischemia.
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PMID:Temporal profile and cellular localization of interleukin-6 protein after focal cerebral ischemia in rats. 1056 72

Inflammatory reactions mediated by cytokines are involved in the pathogenesis of acute stroke. Decrease in circulating levels of protein C (PC) and protein S (PS) induced by inflammatory cytokines has been postulated as a potential mechanism for a procoagulant tendency during acute stroke. The procoagulant state associated with impairments in natural anticoagulants may induce microvascular obstruction leading to a tissue perfusion reduction that worsens cerebral ischemia. Interleukin-6 (IL-6) regulate the synthesis of C4b-binding protein (C4BP), an acute-phase protein that also regulates PS plasma levels. We measured IL-6, C4BP, erythrocyte sedimentation rate (ESR), total and free PS and PC in 44 patients with acute ischemic stroke to determine if IL-6 decreases circulating levels of natural anticoagulants through the C4BP pathway and if these acute changes in natural anticoagulants may have clinical implications. Patients with higher levels of IL-6 had more severe neurologic deficits on admission, greater infarct size, higher levels of acute-phase reactants, and lower levels of free PS. IL-6 was significantly correlated with C4BP, ESR, and free PS levels. PC levels were also lower in the group of patients with greater IL-6, but differences were not statistically significant. No correlations were found between C4BP and natural anticoagulants. Severe neurologic deficit, greater infarct volume, atrial fibrillation, increased levels of inflammatory parameters (ESR and IL-6), and reduced levels of free PS were associated with disabling stroke at 3 months, but only neurologic severity and ESR remained as independent predictors of stroke disability on multiple regression analysis. Inflammatory reactions mediated by IL-6 during the acute phase of stroke influence the modulation of free PS. However, variations in free PS levels do not have implications for clinical outcome in stroke patients. The link between proinflammatory cytokines and free PS in the acute phase of stroke is not related to the C4BP pathway.
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PMID:Interaction between interleukin-6 and the natural anticoagulant system in acute stroke. 1076 81

In the brain, the expression of the pleiotropic cytokine interleukin-6 (IL-6) is enhanced in various chronic or acute central nervous system disorders. However, the significance of IL-6 production in such neuropathologic states remains controversial. The present study investigated the role of IL-6 after cerebral ischemia. First, the authors showed that focal cerebral ischemia in rats early up-regulated the expression of IL-6 mRNA, without affecting the transcription of its receptors (IL-6Ralpha and gp130). Similarly, the striatal injection of N-methyl-D-aspartate (NMDA) in rats, a paradigm of excitotoxic injury, activated the expression of IL-6 mRNA. The involvement of glutamatergic receptor activation was further investigated by incubating cortical neurons with NMDA or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA). NMDA and ionomycin (a calcium ionophore) up-regulated IL-6 mRNA, suggesting that neurons may produce IL-6 in response to the calcium influx mediated through NMDA receptors. The potential role of IL-6 during ischemic/excitotoxic insults was then studied by testing the effect of IL-6 against apoptotic or excitotoxic challenges in cortical cultures. IL-6 did not prevent serum deprivation- or staurosporine-induced apoptotic neuronal death, or AMPA/kainate-mediated excitotoxicity. However, in both mixed and pure neuronal cultures, IL-6 dose-dependently protected neurons against NMDA toxicity. This effect was blocked by a competitive inhibitor of IL-6. Overall, the results suggest that the up-regulation of IL-6 induced by cerebral ischemia could represent an endogenous neuroprotective mechanism against NMDA receptor-mediated injury.
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PMID:Ischemia-induced interleukin-6 as a potential endogenous neuroprotective cytokine against NMDA receptor-mediated excitotoxicity in the brain. 1089 79

Expression of interleukin-6 (IL-6), a neurotrophic cytokine, is up-regulated after cerebral ischemia, but the underlying mechanism of the up-regulation remains unclear. NS-7 is a novel blocker of voltage-sensitive Ca2+ and Na+ channels and is known to reduce cerebral damage by ischemia. The present study was undertaken to examine the association between increases in intracellular Ca2+ concentration induced by membrane depolarization and IL-6 induction. IL-6 expression in rat brain was investigated by immunohistochemistry and Western blot analysis following 3.5-48 h of reperfusion after 1.5 h of occlusion of the middle cerebral artery. NS-7 (1 mg/kg; NS-7 group) or saline (saline group) was injected i.v. 5 min after the start of reperfusion. The saline group showed clear IL-6 expression in various cortical regions, which peaked at 24 h of reperfusion. By contrast, IL-6 expression was significantly suppressed in the NS-7 group throughout the reperfusion period. Microglia activation was also reduced in the NS-7 group. These findings suggest that IL-6 expression may be up-regulated by the increased intracellular Ca2+ concentration triggered by membrane depolarization after cerebral ischemia.
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PMID:Expression of interleukin-6 is suppressed by inhibition of voltage-sensitive Na+/Ca2+ channels after cerebral ischemia. 1094 23

Although anatomical and biochemical properties of the rat entopeduncular nucleus (EPN) closely resemble those of the substantia nigra pars reticulata (SNr), the present study shows that, unlike in the SNr, focal cerebral ischemia does not cause trans-synaptic degeneration of EPN neurons, despite striatal infarction and a similar delayed glial activation in both nuclei. In this study, interleukin-6 (IL-6) expression was found within EPN neurons 3 and 7 days after striatal ischemia. Since it has been reported that neuroprotective properties seem to predominate IL-6 function and that distinct SNr regions which demonstrate low trans-synaptic neuronal degeneration show high IL-6 expression and vice versa, IL-6 expression within partially deafferentiated but surviving EPN neurons could represent an intrinsic neuroprotective mechanism.
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PMID:Interleukin-6 expression in exo-focal neurons after striatal cerebral ischemia. 1156 53

The presence of an inflammatory response in the pathophysiology of acute brain ischemia is relatively well established, but less is known about the anti-inflammatory mechanisms. The aim of the present study was to evaluate part of the immune response in acute stroke patients and to analyze a possible correlation with other hematological parameters, clinical outcome, size of infarct and subtypes of strokes. We prospectively studied 42 stroke patients, without signs of infections or inflammatory diseases, at days 0, 1, 3, 7 and 14, and 39 healthy control subjects. We measured serum levels of the anti-inflammatory cytokine interleukin-10 (IL-10) and the pro-inflammatory cytokine interleukin-6 (IL-6) by ELISA method. We observed a highly inverse correlation between these two molecules in control subjects (r=-0.78, p=0.0000001), and this correlation was lost in stroke patients. Patients had significantly lowered IL-10 serum levels soon after the acute event (p=0.00005), with a slight increase at the seventh day. On the other hand, patients had increased IL-6 serum levels compared with controls after day one until day 14 (p<0.04), with a maximum increase at day 3. Interleukin-6 correlated with clinical outcome whereas interleukin-10 did not. Low levels of interleukin-10 indicate that the antiinflammatory response is down-regulated in acute stroke patients. The pro-inflammatory response begins 24 hours after the onset of acute cerebral ischemia, as indicated by the increased serum levels of interleukin-6. The physiological balance between these two molecules is altered in acute stroke patients.
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PMID:Temporal profile of serum anti-inflammatory and pro-inflammatory interleukins in acute ischemic stroke patients. 1180 50


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