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Keywords:

  • brain ischemia;
  • cytokines;
  • matrix metalloproteinases;
  • microglia;
  • neuroinflammation

Abstract

  1. Top of page
  2. Abstract
  3. Mechanisms of post-ischemic inflammation
  4. Conclusions
  5. Acknowledgements
  6. References

Neuroinflammatory mediators play a crucial role in the pathophysiology of brain ischemia, exerting either deleterious effects on the progression of tissue damage or beneficial roles during recovery and repair. Within hours after the ischemic insult, increased levels of cytokines and chemokines enhance the expression of adhesion molecules on cerebral endothelial cells, facilitating the adhesion and transendothelial migration of circulating neutrophils and monocytes. These cells may accumulate in the capillaries, further impairing cerebral blood flow, or extravasate into the brain parenchyma. Infiltrating leukocytes, as well as resident brain cells, including neurons and glia, may release pro-inflammatory mediators, such as cytokines, chemokines and oxygen/nitrogen free radicals that contribute to the evolution of tissue damage. Moreover, recent studies have highlighted the involvement of matrix metalloproteinases in the propagation and regulation of neuroinflammatory responses to ischemic brain injury. These enzymes cleave protein components of the extracellular matrix such as collagen, proteoglycan and laminin, but also process a number of cell-surface and soluble proteins, including receptors and cytokines such as interleukin-1β. The present work reviewed the role of neuroinflammatory mediators in the pathophysiology of ischemic brain damage and their potential exploitation as drug targets for the treatment of cerebral ischemia.

Abbreviations
BBB

blood–brain barrier

COX-2

cyclooxygenase-2

ICAM-1

intercellular adhesion molecule 1

ICE

interleukin-1β-converting enzyme

IL

interleukin

IL-1ra

interleukin-1 receptor antagonist

iNOS

inducible nitric oxide synthase

MCAO

middle cerebral artery occlusion

MCP-1

monocyte chemotactic protein-1

MMP

matrix metalloproteinase

NO

nitric oxide

TNF

tumor necrosis factor

Stroke is a major cause of death and long-term disability worldwide and is associated with significant clinical and socioeconomical implications, emphasizing the need for effective therapies. In fact, current therapeutic approaches, including antiplatelet and thrombolytic drugs, only partially ameliorate the clinical outcome of stroke patients because such drugs are aimed at preserving or restoring cerebral blood flow rather than at preventing the actual mechanisms associated with neuronal cell death [1,2].

The development of tissue damage after an ischemic insult occurs over time, evolving within hours or several days and is dependent on both the intensity and the duration of the flow reduction, but also on flow-independent mechanisms, especially in the peri-infarct brain regions [3].

A few minutes after the onset of ischemia, tissue damage occurs in the centre of ischemic injury, where cerebral blood flow is reduced by more than 80%. In this core region, cell death rapidly develops as a consequence of the acute energy failure and loss of ionic gradients associated with permanent and anoxic depolarization [4,5]. A few hours later, the infarct expands into the penumbra, an area of partially preserved energy metabolism, as a result of peri-infarct spreading depression and molecular injury pathways that are activated in the cellular and extracellular compartments. At this stage, cellular damage is mainly triggered by excitotoxicity, mitochondrial disturbances, reactive oxygen species production and programmed cell death [6]. The evolution of tissue damage further perpetuates for days or even weeks as a result of secondary phenomena such as vasogenic edema and delayed inflammatory processes [3].

There is increasing evidence demonstrating that neuroinflammatory processes play a pivotal role in the pathophysiology of brain ischemia. The inflammatory cascade is characterized by an immediate phase, which is initiated a few hours after stroke and may last for days and weeks as a delayed tissue reaction to injury [5,7]. In addition to their deleterious contribution to ischemic tissue damage, inflammatory mediators may also exert beneficial effects on stroke recovery [8–10].

Mechanisms of post-ischemic inflammation

  1. Top of page
  2. Abstract
  3. Mechanisms of post-ischemic inflammation
  4. Conclusions
  5. Acknowledgements
  6. References

Cellular response to injury

Post-ischemic inflammation is characterized by a rapid activation of resident microglial cells and by infiltration of neutrophils and macrophages in the injured parenchyma, as demonstrated both in animal models [11,12] and in stroke patients [13–15]. Within hours after the ischemic insult, increased levels of cytokines and chemokines enhance the expression of adhesion molecules, such as intercellular adhesion molecule 1 (ICAM-1), on cerebral endothelial cells, facilitating the adhesion and transendothelial migration of circulating neutrophils and monocytes. These cells may accumulate in the capillaries, further impairing cerebral blood flow, or may extravasate into the brain parenchyma where they release neurotoxic substances, including pro-inflammatory cytokines, chemokines and oxygen/nitrogen free radicals [16]. Four to six hours after ischemia, astrocytes become hypertrophic, followed by activation of microglial cells that evolve into an ameboid type with an enlarged cell body and shortened cellular processes. Twenty-four hours after focal ischemia, an intense microglial reaction develops in the ischemic tissue, particularly in the penumbra, and within days most microglial cells transform into phagocytes [7,17,18]. Activation of microglial cells enhances the inflammatory process and contributes to tissue injury, as demonstrated by the evidence that minocycline or other immunosuppressant drugs reduce infarct damage by preventing microglial activation induced by stroke [19,20]. In addition to their deleterious role, macrophages and microglial cells also contribute to tissue recovery by scavenging necrotic debris and by facilitating plasticity [16]. Indeed, selective ablation of proliferating microglial cells exacerbates brain injury produced by transient middle cerebral artery occlusion (MCAO) in mice [21]. Therefore, depending on the pathophysiologic context, the contribution of inflammatory cells to tissue damage may be different.

Adhesion molecules

The recruitment and infiltration of leukocytes into the brain is promoted by the expression of receptors and adhesion molecules induced by neuroinflammatory mediators that are rapidly released from injured tissue following ischemic insult. Indeed, focal ischemia is associated with significantly elevated levels of cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6 [22,23], and chemokines, such as monocyte chemotactic protein-1 (MCP-1) and macrophage inflammatory protein-1 alpha [24–26]. These mediators induce the expression of the adhesion molecules ICAM-1 [27–30], P-selectin and E-selectin [31,32] and integrins [33,34] on endothelial cells and leukocytes, which promote the adhesion and transendothelial migration of leukocytes [13,35,36]. By this mechanism, activated neutrophils and platelets accumulate in cerebral capillaries and further impair blood perfusion of the injured tissue [37,38]. ICAM-1-deficient or P-selectin-deficient mice show smaller infarct volumes and less neutrophil infiltration following acute stroke compared with wild-type mice [39–41]. However, although there was initial enthusiasm concerning the neuroprotective effect of antibodies raised against adhesion molecules in preclinical studies [32,40,42], administration an antibody against ICAM-1 in humans failed to improve stroke outcome [43,44].

Transcription factors

In rodent models of transient MCAO, inflammatory genes (including cytokines, chemokines, adhesion molecules and pro-inflammatory enzymes) are upregulated a few hours after the insult and remain elevated for days [45–49]. The expression of these pro-inflammatory genes is regulated by transcription factors that are strongly stimulated by the ischemic insult and may exert opposing effects on the evolution of tissue damage [50]. Some transcription factors, such as cyclic AMP response element-binding protein, hypoxia inducible factor-1, nuclear factor-E2-like factor 2, c-fos, p53 and peroxisome proliferator-activated receptors alpha and gamma, are known to prevent ischemic brain damage [51–57]. By contrast, nuclear factor-kappaB, activating transcription factor-3, CCAAT-enhancer binding protein-beta, interferon regulatory factor-1, signal transduction and activator of transcription-3, and early growth response-1 have been demonstrated to mediate post-ischemic neuronal damage [49,58–63]. Many transcription factors, including nuclear factor-kappaB, interferon regulatory factor-1, early growth response-1 and CCAAT-enhancer binding protein-beta promote pro-inflammatory gene expression that, in turn, contributes to secondary neuronal death [50,63]. Recent evidence suggests that the high-mobility-group box 1 protein prompts the induction of pro-inflammatory mediators, including the inducible form of nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), IL-1β and TNF-α, contributing to post-ischemic brain damage [64–66].

Enzymes

Both in human stroke and in animal models, neutrophils, vascular cells and, most notably, neurons, show increased expression of COX-2, an enzyme implicated in post-ischemic inflammation through the production of toxic prostanoids and superoxide [59,67–69]. COX-2-deficient mice develop less inflammation after stroke [69], and post-ischemic treatment with COX-2 inhibitors reduces blood–brain barrier (BBB) damage and leukocyte infiltration induced by transient focal cerebral ischemia in rat [70]. Moreover, it has been recently suggested that COX-2-derived prostaglandin E2 may contribute to ischemic cell damage by disrupting Ca2+ homeostasis in neurons via activation of prostaglandin E2 EP1 receptors [71].

Infiltrating neutrophils, microglia/macrophages and endothelial cells may release toxic amounts of nitric oxide (NO) via the iNOS isoform, which is strongly induced following the ischemic insult both in animal models [72,73] and in stroke patients [74]. Immediately after brain ischemia, NO produced by endothelial NOS exerts beneficial effects by promoting vasodilatation, whereas NO produced during later stages of injury by overactivation of neuronal NOS and de novo expression of iNOS contributes to ischemic tissue injury [75]. Despite substantial evidence underlying the deleterious role of iNOS-derived NO in ischemic pathophysiology [73,75–77], by using chimeric iNOS-deficient mice, a recent study has suggested that this enzyme may not be implicated in the development of brain damage induced by transient focal ischemia [78], but further evidence is needed to confirm this hypothesis.

Excessive production of NO by iNOS is responsible for cytotoxicity by inhibiting ATP-producing enzymes, by producing peroxynitrite and by stimulating other pro-inflammatory enzymes such as COX-2 [79]. Moreover, NO has been suggested to promote ischemic cell death via S-nitrosylation and, thereby, activation of matrix metalloproteinase (MMP)-9 [80].

Recent studies have highlighted the involvement of MMPs in ischemic pathophysiology. MMPs cleave protein components of the extracellular matrix, such as collagen, proteoglycan and laminin, but also process a number of cell-surface and soluble proteins, including receptors, cytokines and chemokines [81]. Thus, in addition to their physiological roles, such as extracellular matrix remodelling, MMPs contribute to the propagation and regulation of neuroinflammatory responses to injury [82,83]. Two members of this class of proteases, the gelatinases MMP-2 and MMP-9, have been strongly implicated in ischemic pathophysiology because they contribute to the disruption of the BBB and hemorrhagic transformation following injury both in animal models [84–87] and in stroke patients [88–90]. Previous studies have described increased expression and activity of gelatinases in the brain following transient focal ischemia [85,91–94]. Moreover, in a rat model of transient MCAO, we have recently demonstrated that gelatinolytic activity increases very early after the start of reperfusion in the regions supplied by the middle cerebral artery. Enzyme activity was mainly detected in neuronal nuclei during the early stages after the insult, but also appeared in the cytosolic compartment and in non-neuronal, presumably glial, cells at later reperfusion times [95].

Treatment with MMP inhibitors or MMP neutralizing antibodies has been reported to decrease infarct volume and to prevent BBB disruption after permanent or transient MCAO in rodents [84,87,96]. We have previously demonstrated that systemic administration of the MMP inhibitor, GM6001, at a dose that significantly prevents the increase of MMP-2 and MMP-9 in the ischemic hemisphere, results in reduced infarct volume in rats subjected to transient MCAO [97].

MMP-9, but not MMP-2 [98], gene knockout is associated with reduced infarct size and less BBB damage in mouse models of ischemic stroke [87,99,100]. The mechanisms of brain damage involve gelatinase-mediated disruption of the BBB integrity, of edema and hemorrhagic transformation, as well as of white matter myelin degradation [83,99]. Recent work has also emphasized the role of MMPs and their endogenous inhibitors (tissue inhibitor of matrix metalloproteinases) in the regulation of neuronal cell death through the modulation of excitotoxicity [101], anoikis [80], calpain activity [102], death receptor activation [103], neurotrophic factor bioavailability [104] and production of neurotoxic products [80,105]. Moreover, these proteases may regulate inflammatory processes because they have been involved in the processing of pro-inflammatory cytokines, such as IL-1β, into its biologically active form both in vitro [106] and under ischemic conditions in vivo [97]. Indeed, we have demonstrated that systemic administration of a neuroprotective dose of GM6001 prevents the early increase of IL-1β in the cortex of rats subjected to transient MCAO. This suggests that, in addition to extracellular matrix degradation, MMPs might elicit some direct, pathogenic effects that contribute to brain tissue damage under various neuropathological conditions, including brain ischemia.

A recent study has also demonstrated that the extracellular MMP inducer is strongly upregulated in endothelial cells and astrocytes of peri-focal regions 2–7 days after permanent MCAO in mice. The expression of the extracellular MMP inducer has been spatially and temporally associated with the delayed increase of MMP-9, suggesting its involvement in neurovascular remodelling after stroke [107]. Accordingly, inhibition of MMP-9 between 7 and 14 days after stroke results in a substantial reduction in the number of neurons and new vessels implicated in neurovascular remodelling [108]. This was associated with reduced vascular endothelial growth factor signalling resulting from MMP inhibition [108]. These findings underscore the complexity of MMP activity during tissue injury, ranging from detrimental effects during the early phases after stroke to beneficial roles at later stages [109].

Cytokines

After an ischemic insult, several cytokines are upregulated in cells of the immune system, but also in resident brain cells, including neurons and glia [110]. While some cytokines, such as IL-1, appear to exacerbate cerebral injury, others (e.g. IL-6, IL-10 and transforming growth factor-beta) seem to provide neuroprotection [111].

The pro-inflammatory cytokine IL-1β represents a crucial mediator of neurodegeneration induced by excitatory or traumatic brain injury and, most notably, by experimental cerebral ischemia in rodents [112] (Fig. 1). Focal brain ischemia produced by either permanent or transient MCAO in rats results in a significant induction of IL-1β mRNA [23,113,114]. Accordingly, IL-1β protein levels increase very early following permanent MCAO [115,116] and peak within hours of reperfusion in transient focal ischemic models in rodents [97,117,118]. The main source of the cytokine after cerebral ischemia are endothelial cells, microglia and macrophages, although it may also be expressed by neurons and astrocytes [119,120]. Activation of p38 mitogen-activated protein kinase has been suggested to underlie IL-1β production by astrocytes and microglia during ischemic injury in rats [121–123]. Moreover, there is evidence suggesting that activation of the Toll-like receptor-4 may be responsible for (pro-)IL-1β production following cerebral ischemia [124].

image

Figure 1.  Putative mechanisms implicated in IL-1β-induced neuroinflammation after stroke injury. CNS, central nervous system.

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Intracerebral injection of IL-1β neutralizing antibody to rats reduces ischemic brain damage [125], and both intracerebroventricular and systemic administration of IL-1 receptor antagonist (IL-1ra) markedly reduces brain damage induced by focal stroke, further implicating IL-1β in ischemic pathophysiology [126–129]. IL-1β expression is closely associated with an upregulation of ICAM and endothelial leucocyte adhesion molecule, which reach a peak between 6 and 12 h after the onset of ischemia [130]. ICAM-1-deficient mice suffer smaller infarcts after transient MCAO, suggesting that part of the IL-1β-dependent injury is mediated by the activation of ICAM-1 [41].

IL-1β is synthesized as a precursor molecule, pro-IL-1β, which is cleaved and converted into the mature, biologically active form of the cytokine by caspase-1, formerly referred to as interleukin-1β-converting enzyme (ICE) [131–133]. Inhibition of caspase-1 by Ac-YVAD.cmk affords neuroprotection in rodent models of permanent [134] or transient [117] MCAO, and evidence from knockout mice indicates that caspase-1 is important in the development of cerebral ischemic damage [135,136]. However, to date, it is not clear whether neuroprotection yielded by caspase-1-preferring inhibitors is mediated by reduced IL-1β production or by interference with the cell-death process [137]. Although most studies have clearly established the role of ICE in the maturation of IL-1β, evidence from ICE-deficient mice and from in vitro studies suggests that cytokine activation might also involve other mechanisms [138–140]. Interestingly, in vitro studies have described the involvement of MMPs in cytokine processing. The conversion of recombinant pro-IL-1β into mature IL-1β has been demonstrated to occur after co-incubation with recombinant MMP-2 or MMP-9, the latter operating a more effective and rapid cleavage [106].

We have recently demonstrated that the early increase of IL-1β detected in the ischemic cortex of rats subjected to transient MCAO is not associated with increased activity of caspase-1 [97]. By contrast, as discussed above, cytokine production during ischemia-reperfusion injury appears to be dependent on MMP activity because systemic administration of the MMP inhibitor, GM6001, prevents the early increase of mature IL-1β in the ischemic cortex [97] (Fig. 1). As cytokines, such as IL-1β, regulate the expression and the activation of MMPs, a complex cross-regulation does occur between these neuroinflammatory mediators, and further studies are needed to understand their spatio-temporal occurrence during stroke injury.

Despite being structurally and functionally correlated with IL-1, results from animal studies suggest that IL-18 is not involved in stroke pathophysiology [141]. However, blood levels of the cytokine increase in acute stroke patients and appear to be predictive of unfavourable clinical outcome [142,143].

In addition to IL-1β, brain injury induced by focal ischemia is characterized by a significant and rapid upregulation of TNF-α, as demonstrated both in animal models and in stroke patients. Increased expression of TNF-α has been described in neurones, especially during the first hours after the ischemic insult, and at later stages in microglia/macrophages and in cells of the peripheral immune system [22,144–147]. A focal ischemic insult has also been shown to upregulate expression of the TNF-α receptor, p75, in resident microglia and infiltrating macrophages of the injured hemisphere [145,148].

Administration of neutralizing antibodies raised against TNF-α or soluble TNF receptor 1 results in reduced infarct size in rats subjected to permanent MCAO, suggesting that the cytokine exacerbates ischemic injury [28,149–151]. However, to date, the role of TNF-α has not been fully clarified because neuronal damage caused by focal brain ischemia is exacerbated in mice genetically deficient in p55 TNF receptors [152]. The pleiotropic activities of TNF are mediated by two structurally related, but functionally distinct, receptors, namely p55 and p75. Selective deletion of the p55 gene results in increased brain damage, as compared with wild-type and p75-deficient mice following transient focal ischemia [153]. Moreover, ischemic preconditioning by TNF-α has been suggested to occur via p55 receptor upregulation in neurons [154]. Thus, the roles of p55 and p75 in modulating cell death/survival remain unclear, as both receptors may activate intracellular mechanisms contributing either to the induction of cell-death mechanisms or to anti-inflammatory and anti-apoptotic functions [155].

IL-6 expression significantly increases in the acute phase of cerebral ischemia [156,157] and remains elevated in neurons and reactive microglia of the ischemic penumbra up to 14 days after the ischemic insult [158,159]. In patients with acute brain ischemia, plasma concentrations of IL-6 are strongly associated with stroke severity and long-term clinical outcome [160–162]. In a double-blind clinical trial on patients with acute stroke, intravenous administration of human recombinant IL-1ra ameliorates clinical outcome and reduces blood concentrations of IL-6 [163]. This is in contrast to the results from animal studies suggesting that IL-6 may exert a neuroprotective role during stroke. In fact, intracerebroventricular injection of recombinant IL-6 reduces ischemic brain damage induced by permanent MCAO in rat [164]. It has been suggested that increased levels of the endogenous cytokine prevent damaged neurons from undergoing apoptosis via signal transduction and activator of transcription-3 activation [165].

Among other cytokines involved in stroke pathophysiology, IL-10 and transforming growth factor-beta have been demonstrated to have anti-inflammatory effects, providing significant protection against ischemic brain damage [166].

Chemokines

Chemokines are regulatory polypeptides that mediate cellular communication and leukocyte recruitment in inflammatory and immune responses. Increased mRNA expression for MCP-1 and macrophage inflammatory protein-1 alpha has been described in the rat brain after focal cerebral ischemia, and both chemokines have been suggested to contribute to tissue damage via recruitment of inflammatory cells [25,167,168]. Expression of MCP-1 has been described in neurons 12 h after focal brain ischemia, but also in astrocytes and microglia at later stages following the insult [26,169]. The MCP-1 levels are also increased in the cerebrospinal fluid of stroke patients [170]. MCP-1 is a major factor driving leukocyte infiltration in the brain parenchyma [171]. Mice deficient in MCP-1 develop less infarct volume as a consequence of focal brain ischemia [172]. Similarly, in mice deficient in the gene for the MCP-1 receptor, CCR2, transient focal ischemia results in reduced infarct size, edema, leukocyte infiltration and expression of inflammatory mediators [173]. Moreover, MCP-1, as well as stromal cell-derived factor-1α, have been shown to trigger migration of newly formed neuroblasts from neurogenic regions to ischemic damaged areas [169,174].

Stromal cell-derived factor-1α expression is increased in the ischemic penumbra, particularly in perivascular astrocytes [175]. This chemokine has been suggested to promote neuroprotection by increasing bone marrow-derived cell targeting to the ischemic brain and by improving local cerebral blood flow [176,177]. The crucial involvement of chemokines in regulating cell migration, promoting the interaction of stem cells with ischemia-damaged host tissue, might be useful for improving the clinical application of stem cell therapy.

Another chemokine implicated in ischemic pathophysiology is fractalkine, whose expression is increased in neurons and in some endothelial cells after a focal ischemic insult. Interestingly, expression of its receptor, CX3CR1, was observed only in microglia/macrophages, suggesting that fractalkine is involved in neuron–microglia signalling [178]. In fact, this chemokine participates in leukocyte migration and in the activation and chemoattraction of microglia into the infracted tissue [178]. Indeed, fractalkine-deficient mice exhibit a smaller infarct size and lower mortality after transient focal cerebral ischemia, further underlying the detrimental effect of this chemokine on stroke outcome [179].

Conclusions

  1. Top of page
  2. Abstract
  3. Mechanisms of post-ischemic inflammation
  4. Conclusions
  5. Acknowledgements
  6. References

Neuroinflammatory mechanisms activated following an ischemic insult play a complex role in the pathophysiology of cerebral ischemia (Fig. 2). The induction of pro-inflammatory genes may occur very early after the insult and commonly aggravate tissue damage. Thus, early inflammatory responses appear to contribute to ischemic injury, whereas late responses may represent endogenous mechanisms of recovery and repair. The switch from detrimental to beneficial effects seems to depend on the strength and the duration of the insult and is crucial for determining the time-window for an effective pharmacotherapy.

image

Figure 2.  Main pathways implicated in the neuroinflammatory response to ischemic injury. CBF, cerebral blood flow; MIP-1α, macrophage inflammatory protein-1 alpha; ROS, reactive oxygen species.

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Given its pivotal role in stroke pathophysiology, the IL-1 system represents an attractive therapeutic target (Fig. 1). Indeed, IL-1ra reduces brain injury in animal models of cerebral ischemia and, in a recent randomized clinical trial, intravenous administration of recombinant human IL-1ra in patients with acute stroke provided evidence for safety and for effective reduction of peripheral inflammatory markers [163]. Recombinant human IL-1ra administered intravenously has also been shown to penetrate the human brain at experimentally therapeutic concentrations [180], although its slow penetration into cerebrospinal fluid [181] will probably result in subtherapeutic concentrations during the crucial early hours of an acute stroke. Further work is necessary to identify a suitable therapeutic regime prior to phase II/III clinical trials.

Acknowledgements

  1. Top of page
  2. Abstract
  3. Mechanisms of post-ischemic inflammation
  4. Conclusions
  5. Acknowledgements
  6. References

Financial support from the Italian Ministry of University and Research (PRIN prot. 2006059200_002) is gratefully acknowledged.

References

  1. Top of page
  2. Abstract
  3. Mechanisms of post-ischemic inflammation
  4. Conclusions
  5. Acknowledgements
  6. References
  • 1
    Gladstone DJ, Black SE, Hakim AM & Heart and Stroke Foundation of Ontario Centre of Excellence in Stroke Recovery (2002) Toward wisdom from failure: lessons from neuroprotective stroke trials and new therapeutic directions. Stroke 33, 21232136.
  • 2
    Lo EH, Dalkara T & Moskowitz MA (2003) Mechanisms, challenges and opportunities in stroke. Nat Rev Neurosci 4, 21232126.
  • 3
    Hossmann KA (2006) Pathophysiology and therapy of experimental stroke. Cell Mol Neurobiol 26, 10571084.
  • 4
    Hossmann KA (1994) Viability thresholds and the penumbra of focal ischemia. Ann Neurol 36, 557565.
  • 5
    Dirnagl U, Iadecola C & Moskowitz MA (1999) Pathobiology of ischaemic stroke: an integrated view. Trends Neurosci 22, 391397.
  • 6
    Lo EH, Moskowitz MA & Jacobs TP (2005) Exciting, radical, sucidal: how brain cells die after stroke. Stroke 36, 189192.
  • 7
    Stoll G, Jander S & Schroeter M (1998) Inflammation and glial responses in ischemic brain lesions. Prog Neurobiol 56, 149171.
  • 8
    Del Zoppo GJ, Becker KJ & Hallenbeck JM (2001) Inflammation after stroke: is it harmful? Arch Neurol 58, 669672.
  • 9
    Kriz J (2006) Inflammation in ischemic brain injury: timing is important. Crit Rev Neurobiol 18, 145157.
  • 10
    Denes A, Vidyasagar R, Feng J, Narvainen J, McColl BW, Kauppinen RA & Allan SM (2007) Proliferating resident microglia after focal cerebral ischaemia in mice. J Cereb Blood Flow Metab 27, 19411953.
  • 11
    Schilling M, Besselmann M, Leonhard C, Mueller M, Ringelstein EB & Kiefer R (2003) Microglial activation precedes and predominates over macrophage infiltration in transient focal cerebral ischemia: a study in green fluorescent protein transgenic bone marrow chimeric mice. Exp Neurol 183, 2533.
  • 12
    Tanaka R, Komine-Kobayashi M, Mochizuki H, Yamada M, Furuya T, Migita M, Shimada T, Mizuno Y & Urabe T (2003) Migration of enhanced green fluorescent protein expressing bone marrow-derived microglia/macrophage into the mouse brain following permanent focal ischemia. Neuroscience 117, 531539.
  • 13
    Lindsberg PJ, Carpén O, Paetau A, Karjalainen-Lindsberg ML & Kaste M (1996) Endothelial ICAM-1 expression associated with inflammatory cell response in human ischemic stroke. Circulation 94, 939945.
  • 14
    Gerhard A, Neumaier B, Elitok E, Glatting G, Ries V, Tomczak R, Ludolph AC & Reske SN (2000) In vivo imaging of activated microglia using [11C]PK11195 and positron emission tomography in patients after ischemic stroke. Neuroreport 11, 29572960.
  • 15
    Price CJ, Menon DK, Peters AM, Ballinger JR, Barber RW, Balan KK, Lynch A, Xuereb JH, Fryer T, Guadagno JV et al. (2004) Cerebral neutrophil recruitment, histology, and outcome in acute ischemic stroke: an imaging-based study. Stroke 35, 16591664.
  • 16
    Danton GH & Dietrich WD (2003) Inflammatory mechanisms after ischemia and stroke. J Neuropathol Exp Neurol 62, 127136.
  • 17
    Zhang ZG, Chopp M & Powers C (1997) Temporal profile of microglial response following transient (2 h) middle cerebral artery occlusion. Brain Res 774, 189198.
  • 18
    Schilling M, Besselman M, Muller M, Strecker JK, Ringelstein EB & Kiefer R (2005) Predominant phagocytic activity of resident microglia over hematogenous macrophages following transient cerebral brain ischemia: an investigation using green fluorescent protein transgenic bone marrow chimeric mice. Exp Neurol 196, 290297.
  • 19
    Yrjanheikki J, Tikka T, Keinanen R, Goldsteins G, Chan PH & Koistinaho J (1999) A tetracycline derivative, minocycline, reduces inflammation and protects against focal cerebral ischemia with a wide therapeutic window. Proc Natl Acad Sci USA 96, 1349613500.
  • 20
    Hailer NP (2008) Immunosuppression after traumatic or ischemic CNS damage: it is neuroprotective and illuminates the role of microglial cells. Prog Neurobiol 84, 211233.
  • 21
    Lalancette-Hébert M, Gowing G, Simard A, Weng YC & Kriz J (2007) Selective ablation of proliferating microglial cells exacerbates ischemic injury in the brain. J Neurosci 27, 25962605.
  • 22
    Liu T, Clark RK, McDonnell PC, Young PR, White RF, Barone FC & Feuerstein GZ (1994) Tumor necrosis factor-alpha expression in ischemic neurons. Stroke 25, 14811488.
  • 23
    Wang X, Yue TL, Barone FC, White RF, Gagnon RC & Feuerstein GZ (1994) Concomitant cortical expression of TNF-alpha and IL-1 beta mRNAs follows early response gene expression in transient focal ischemia. Mol Chem Neuropathol 23, 103114.
  • 24
    Kim JS, Gautam SC, Chopp M, Zaloga C, Jones ML, Ward PA & Welch KM (1995b) Expression of monocyte chemoattractant protein-1 and macrophage inflammatory protein-1 after focal cerebral ischemia in the rat. J Neuroimmunol 56, 127134.
  • 25
    Wang X, Yue TL, Barone FC & Feuerstein GZ (1995) Monocyte chemoattractant protein-1 messenger RNA expression in rat ischemic cortex. Stroke 26, 661665.
  • 26
    Che X, Ye W, Panga L, Wu DC & Yang GY (2001) Monocyte chemoattractant protein-1 expressed in neurons and astrocytes during focal ischemia in mice. Brain Res 902, 171177.
  • 27
    Stanimirovic DB, Wong J, Shapiro A & Durkin JP (1997) Increase in surface expression of ICAM-1, VCAM-1 and E-selectin in human cerebromicrovascular endothelial cells subjected to ischemia-like insults. Acta Neurochir Suppl 70, 1216.
  • 28
    Yang GY, Gong C, Qin Z, Ye W, Mao Y & Bertz AL (1998) Inhibition of TNFalpha attenuates infarct volume and ICAM-1 expression in ischemic mouse brain. Neuroreport 9, 21312134.
  • 29
    Yang GY, Schielke GP, Gong C, Mao Y, Ge HL, Liu XH & Betz AL (1999) Expression of tumor necrosis factor-alpha and intercellular adhesion molecule-1 after focal cerebral ischemia in interleukin-1beta converting enzyme deficient mice. J Cereb Blood Flow Metab 19, 11091117.
  • 30
    Schöning B, Elepfandt P, Daberkow N, Rupprecht S, Stockhammer F, Stoltenburg G, Volk HD & Woiciechowsky C (2002) Differences in immune cell invasion into the cerebrospinal fluid and brain parenchyma during cerebral infusion of interleukin-1beta. Neurol Sci 23, 211218.
  • 31
    Zhang R, Chopp M, Zhang Z, Jiang N & Powers C (1998b) The expression of P- and E-selectins in three models of middle cerebral artery occlusion. Brain Res 785, 207214.
  • 32
    Huang J, Choudhri TF, Winfree CJ, McTaggart RA, Kiss S, Mocco J, Kim LJ, Protopsaltis TS, Zhang Y, Pinsky DJ et al. (2000) Postischemic cerebrovascular E-selectin expression mediates tissue injury in murine stroke. Stroke 31, 30473053.
  • 33
    Kim JS, Chopp M, Chen H, Levine SR, Carey JL & Welch KM (1995a) Adhesive glycoproteins CD11a and CD18 are upregulated in the leukocytes from patients with ischemic stroke and transient ischemic attacks. J Neurol Sci 128, 4550.
  • 34
    Fiszer U, Korczak-Kowalska G, Palasik W, Korlak J, Górski A & Członkowska A (1998) Increased expression of adhesion molecule CD18 (LFA-1beta) on the leukocytes of peripheral blood in patients with acute ischemic stroke. Acta Neurol Scand 97, 221224.
  • 35
    Matsuo Y, Onodera H, Shiga Y, Shozuhara H, Ninomiya M, Kihara T, Tamatani T, Miyasaka M & Kogure K (1994) Role of cell adhesion molecules in brain injury after transient middle cerebral artery occlusion in the rat. Brain Res 656, 344352.
  • 36
    Okada Y, Copeland BR, Mori E, Tung MM, Thomas WS & del Zoppo GJ (1994) P-selectin and intercellular adhesion molecule-1 expression after focal brain ischemia and reperfusion. Stroke 25, 202211.
  • 37
    Del Zoppo GJ, Schmid-Schönbein GW, Mori E, Copeland BR & Chang CM (1991) Polymorphonuclear leukocytes occlude capillaries following middle cerebral artery occlusion and reperfusion in baboons. Stroke 22, 12761283.
  • 38
    Mori E, del Zoppo GJ, Chambers JD, Copeland BR & Arfors KE (1992) Inhibition of polymorphonuclear leukocyte adherence suppresses no-reflow after focal cerebral ischemia in baboons. Stroke 23, 712718.
  • 39
    Connolly ES Jr, Winfree CJ, Springer TA, Naka Y, Liao H, Yan SD, Stern DM, Solomon RA, Gutierrez-Ramos JC & Pinsky DJ (1996) Cerebral protection in homozygous null ICAM-1 mice after middle cerebral artery occlusion. Role of neutrophil adhesion in the pathogenesis of stroke. J Clin Invest 97, 209216.
  • 40
    Connolly ES, Winfree CJ, Prestigiacomo CJ, Kim SC, Choudhri TF, Hoh BL, Naka Y, Solomon RA & Pinsky DJ (1997) Exacerbation of cerebral injury in mice that express the P-selectin gene: identification of P-selectin blockade as a new target for the treatment of stroke. Circ Res 81, 304310.
  • 41
    Soriano SG, Lipton SA, Wang YMF, Xiao M, Springer TA, Gutierrezramo JC & Hickey PR (1996) Intercellular adhesion molecule-1-deficient mice are less susceptible to cerebral ischemia-reperfusion injury. Ann Neurol 39, 618624.
  • 42
    Chopp M, Li Y, Jiang N, Zhang RL & Prostak J (1996) Antibodies against adhesion molecules reduce apoptosis after transient middle cerebral artery occlusion in rat brain. J Cereb Blood Flow Metab 16, 578584.
  • 43
    Enlimomab Acute Stroke Trial Investigators (2001) Use of anti-ICAM-1 therapy in ischemic stroke: results of the enlimomab acute stroke trial. Neurology 57, 14281434.
  • 44
    Furuya K, Takeda H, Azhar S, McCarron RM, Chen Y, Ruetzler CA, Wolcott KM, DeGraba TJ, Rothlein R, Hugli TE et al. (2001) Examination of several potential mechanisms for the negative outcome in a clinical stroke trial of enlimomab, a murine anti-human intercellular adhesion molecule-1 antibody: a bedside-to-bench study. Stroke 32, 26652674.
  • 45
    Soriano MA, Tessier M, Certa U & Gil R (2000) Parallel gene expression monitoring using oligonucleotide probe arrays of multiple transcripts with an animal model of focal ischemia. J Cereb Blood Flow Metab 20, 10451055.
  • 46
    Vemuganti R, Bowen KK, Dhodda VK, Song G, Franklin JL, Gavva NR & Dempsey RJ (2002) Gene expression analysis of spontaneously hypertensive rat cerebral cortex following transient focal ischemia. J Neurochem 83, 10721086.
  • 47
    Vemuganti R, Dempsey RJ & Bowen KK (2004) Inhibition of intercellular adhesion molecule-1 protein expression by antisense oligonucleotides is neuroprotective after transient middle cerebral artery occlusion in rat. Stroke 35, 179184.
  • 48
    Lu XC, Williams AJ, Yao C, Berti R, Hartings JA, Whipple R, Vahey MT, Polavarapu RG, Woller KL, Tortella FC et al. (2004) Microarray analysis of acute and delayed gene expression profile in rats after focal ischemic brain injury and reperfusion. J Neurosci Res 77, 843857.
  • 49
    Kapadia R, Tureyen K, Bowen KK, Kalluri H, Johnson PF & Vemuganti R (2006) Decreased brain damage and curtailed inflammation in transcription factor CCAAT/enhancer binding protein beta knockout mice following transient focal cerebral ischemia. J Neurochem 98, 17181731.
  • 50
    Yi JH, Park SW, Kapadia R & Vemuganti R (2007) Role of transcription factors in mediating post-ischemic cerebral inflammation and brain damage. Neurochem Int 50, 10141027.
  • 51
    Bergeron M, Yu AY, Solway KE, Semenza GL & Sharp FR (1999) Induction of hypoxia-inducible factor-1 (HIF-1) and its target genes following focal ischaemia in rat brain. Eur J Neurosci 11, 41594170.
  • 52
    Tanaka K, Nogawa S, Ito D, Suzuki S, Dembo T, Kosakai A & Fukuchi Y (2000) Activated phosphorylation of cyclic AMP response element binding protein is associated with preservation of striatal neurons after focal cerebral ischemia in the rat. Neuroscience 100, 345354.
  • 53
    Cho S, Park EM, Kim Y, Liu N, Gal J, Volpe BT & Joh TH (2001) Early c-Fos induction after cerebral ischemia: a possible neuroprotective role. J Cereb Blood Flow Metab 21, 550556.
  • 54
    Maeda K, Hata R, Gillardon F & Hossman KA (2001) Aggravation of brain injury after focal cerebral ischemia in p53-deficient mice. Mol Brain Res 88, 5461.
  • 55
    Sundararajan S, Gamboa JL, Victor AN, Wanderi EW, Lust D & Landreth GE (2005) Peroxisome proliferator-activated receptor-γ ligands reduce inflammation and infarction size in transient focal ischemia. Neuroscience 130, 685696.
  • 56
    Luo Y, Yin W, Signore AP, Zhang F, Hong Z, Wang S, Graham SH & Chen J (2006) Neuroprotection against focal ischemic brain injury by the peroxisomal proliferator-activated receptor-γ agonist rosiglitazone. J Neurochem 97, 435448.
  • 57
    Tureyen K, Kapadia R, Bowen KK, Satriotomo R, Liang J, Feinstein DL & Vemuganti R (2007) Peroxisome proliferator-activated receptor-gamma agonists induce neuroprotection following transient focal ischemia in normotensive, normoglycemic as well as hypertensive and type-2 diabetic rodents. J Neurochem 101, 4156.
  • 58
    O’Neill LA & Kaltschmidt C (1997) NF-kappa B: a crucial transcription factor for glial and neuronal cell function. Trends Neurosci 20, 252258.
  • 59
    Iadecola C, Forster C, Nogawa S, Clark HB & Ross ME (1999) Cyclooxygenase-2 immunoreactivity in the human brain following cerebral ischemia. Acta Neuropathol 98, 914.
  • 60
    Stephenson D, Yin T, Smalstig EB, Hsu MA, Panetta J, Little S & Clemens J (2000) Transcription factor nuclear factor-kappa B is activated in neurons after focal cerebral ischemia. J Cereb Blood Flow Metab 20, 592603.
  • 61
    Ohba N, Maeda M, Nakagomi S, Muraoka M & Kiyama H (2003) Biphasic expression of activating transcription factor-3 in neurons after cerebral ischemia. Mol Brain Res 115, 147156.
  • 62
    Satriotomo I, Bowen K & Vemuganti R (2006) JAK2 and STAT3 activation contributes to neuronal damage following transient focal cerebral ischemia. J Neurochem 98, 13531368.
  • 63
    Tureyen K, Brooks N, Bowen K, Svaren J & Vemuganti R (2008) Transcription factor early growth response-1 induction mediates inflammatory gene expression and brain damage following transient focal ischemia. J Neurochem 105, 13131324.
  • 64
    Faraco G, Fossati S, Bianchi ME, Patrone M, Pedrazzi M, Sparatore B, Moroni F & Chiarugi A (2007) High mobility group box 1 protein is released by neural cells upon different stresses and worsens ischemic neurodegeneration in vitro and in vivo. J Neurochem 103, 590603.
  • 65
    Liu K, Mori S, Takahashi HK, Tomono Y, Wake H, Kanke T, Sato Y, Hiraga N, Adachi N, Yoshino T et al. (2007) Anti-high mobility group box 1 monoclonal antibody ameliorates brain infarction induced by transient ischemia in rats. FASEB J 21, 39043916.
  • 66
    Qiu J, Nishimura M, Wang Y, Sims JR, Qiu S, Savitz SI, Salomone S & Moskowitz MA (2008) Early release of HMGB-1 from neurons after the onset of brain ischemia. J Cereb Blood Flow Metab 28, 927938.
  • 67
    Nogawa S, Zhang F, Ross ME & Iadecola C (1997) Cyclo-oxygenase-2 gene expression in neurons contributes to ischemic brain damage. J Neurosci 17, 27462755.
  • 68
    Bidmon HJ, Oermann E, Schiene K, Schmitt M, Kato K, Asayama K, Witte OW & Zilles K (2000) Unilateral upregulation of cyclooxygenase-2 following cerebral, cortical photothrombosis in the rat: suppression by MK-801 and co-distribution with enzymes involved in the oxidative stress cascade. J Chem Neuroanat 20, 163176.
  • 69
    Iadecola C, Niwa K, Nogawa S, Zhao X, Nagayama M, Araki E, Morham S & Ross ME (2001) Reduced susceptibility to ischemic brain injury and N-methyl-D-aspartate-mediated neurotoxicity in cyclooxygenase-2-deficient mice. Proc Natl Acad Sci USA 98, 12941299.
  • 70
    Candelario-Jalil E, González-Falcón A, García-Cabrera M, León OS & Fiebich BL (2007) Post-ischaemic treatment with the cyclooxygenase-2 inhibitor nimesulide reduces blood–brain barrier disruption and leukocyte infiltration following transient focal cerebral ischaemia in rats. J Neurochem 100, 11081120.
  • 71
    Kawano T, Anrather J, Zhou P, Park L, Wang G, Frys KA, Kunz A, Cho S, Orio M & Iadecola C (2006) Prostaglandin E2 EP1 receptors: downstream effectors of COX-2 neurotoxicity. Nat Med 12, 225229.
  • 72
    Nakashima MN, Yamashita K, Kataoka Y, Yamashita YS & Niwa M (1995) Time course of nitric oxide synthase activity in neuronal, glial, and endothelial cells of rat striatum following focal cerebral ischemia. Cell Mol Neurobiol 15, 341349.
  • 73
    Iadecola C, Zhang F, Casey R, Clark HB & Ross ME (1996) Inducible nitric oxide synthase gene expression in vascular cells after transient focal cerebral ischemia. Stroke 27, 13731380.
  • 74
    Forster C, Clark HB, Ross ME & Iadecola C (1999) Inducible nitric oxide synthase expression in human cerebral infarcts. Acta Neuropathol 97, 215220.
  • 75
    Moro MA, Cárdenas A, Hurtado O, Leza JC & Lizasoain I (2004) Role of nitric oxide after brain ischaemia. Cell Calcium 36, 265275.
  • 76
    Iadecola C, Zhang F, Casey R, Nagayama M & Ross ME (1997) Delayed reduction of ischemic brain injury and neurological deficits in mice lacking the inducible nitric oxide synthase gene. J Neurosci 17, 91579164.
  • 77
    Murphy S & Gibson CL (2007) Nitric oxide, ischaemia and brain inflammation. Biochem Soc Trans 35, 11331137.
  • 78
    Prüss H, Prass K, Ghaeni L, Milosevic M, Muselmann C, Freyer D, Royl G, Reuter U, Baeva N, Dirnagl U et al. (2008) Inducible nitric oxide synthase does not mediate brain damage after transient focal cerebral ischemia in mice. J Cereb Blood Flow Metab 28, 526539.
  • 79
    Nogawa S, Forster C, Zhang F, Nagayama M, Ross ME & Iadecola C (1998) Interaction between inducible nitric oxide synthase and cyclooxygenase-2 after cerebral ischemia. Proc Natl Acad Sci USA 95, 1096610971.
  • 80
    Gu Z, Kaul M, Yan B, Kriedel SJ, Cul J, Strongin A, Smith JW, Liddington RC & Lipton SA (2002) S-nitrosylation of matrix metalloproteinases: signaling pathway to neuronal cell death. Science 297, 11861190.
  • 81
    Sternlicht MD & Werb Z (2001) How matrix metalloproteinases regulate cell behaviour. Annu Rev Cell Dev Biol 17, 463516.
  • 82
    Rosenberg GA (2002) Matrix metalloproteinases in neuroinflammation. Glia 39, 279291.
  • 83
    Cunningham LA, Wetzel M & Rosenberg GA (2005) Multiple roles for MMPs and TIMPs in cerebral ischemia. Glia 50, 329339.
  • 84
    Romanic AM, White RF, Arleth AJ, Ohlstein EH & Barone FC (1998) Matrix metalloproteinase expression increases after cerebral focal ischemia in rats: inhibition of matrix metalloproteinase-9 reduces infarct size. Stroke 29, 10201030.
  • 85
    Rosenberg GA, Estrada EY & Dencoff JE (1998) Matrix metalloproteinases and TIMPs are associated with blood–brain barrier opening after reperfusion in rat brain. Stroke 29, 21892195.
  • 86
    Heo JH, Lucero J, Abumiya T, Koziol JA, Copeland BR & del Zoppo GJ (1999) Matrix metalloproteinases increase very early during experimental focal cerebral ischemia. J Cereb Blood Flow Metab 19, 624633.
  • 87
    Asahi M, Asahi K, Jung JC, del Zoppo GJ, Fini ME & Lo EH (2000) Role for matrix metalloproteinase 9 after focal cerebral ischemia: effects of gene knockdown and enzyme inhibition with BB-94. J Cereb Blood Flow Metab 20, 16811689.
  • 88
    Horstmann S, Kalb P, Koziol J, Gardner H & Wagner S (2003) Profiles of matrix metalloproteinases, their inhibitors, and laminin in stroke patients: influence of different therapies. Stroke 34, 21652170.
  • 89
    Rosell A, Ortega-Aznar A, Alvarez-Sabin J, Fernandez-Cadenas I, Ribo M, Molina CA, Lo EH & Montanter J (2006) Increased brain expression of matrix metalloproteinase-9 after ischemic and hemorrhagic human stroke. Stroke 37, 13991406.
  • 90
    Rosell A, Cuadrado E, Ortega-Aznar A, Hernández-Guillamon M, Lo EH & Montaner J (2008) MMP-9-positive neutrophil infiltration is associated to blood–brain barrier breakdown and basal lamina type iv collagen degradation during hemorrhagic transformation after human ischemic stroke. Stroke 39, 11211126.
  • 91
    Planas AM, Sole S & Justicia C (2001) Expression and activation of matrix metalloproteinase-2 and -9 in rat brain after transient focal cerebral ischemia. Neurobiol Dis 8, 834846.
  • 92
    Rosenberg GA, Cunningham LA, Wallace J, Alexander S, Estrada EY, Grossetete M, Razhagi A, Miller K & Gearing A (2001) Immunohistochemistry of matrix metalloproteinases in reperfusion injury in rat brain: activation of MMP-9 linked to stromelysin-1 and microglia in cell cultures. Brain Res 893, 104112.
  • 93
    Gu Z, Cui J, Brown S, Fridman R, Mobashery S, Strongin AY & Lipton SA (2005) A highly specific inhibitor of matrix metalloproteinase-9 rescues laminin from proteolysis and neurons from apoptosis in transient focal cerebral ischemia. J Neurosci 25, 64016408.
  • 94
    Yang Y, Estrada EY, Thompson JF, Liu W & Rosenberg GA (2007) Matrix metalloproteinase-mediated disruption of tight junction proteins in cerebral vessels is reversed by synthetic matrix metalloproteinase inhibitor in focal ischemia in rat. J Cereb Blood Flow Metab 27, 697709.
  • 95
    Amantea D, Corasaniti MT, Mercuri NB, Bernardi G & Bagetta G (2008) Brain regional and cellular localization of gelatinase activity in rat that have undergone transient middle cerebral artery occlusion. Neuroscience 152, 817.
  • 96
    Gasche Y, Copin JC, Sugawara T, Fujimura M & Chan PH (2001) Matrix metalloproteinase inhibition prevents oxidative stress associated blood–brain barrier disruption after transient focal cerebral ischemia. J Cereb Blood Flow Metab 21, 13931400.
  • 97
    Amantea D, Russo R, Gliozzi M, Fratto V, Berliocchi L, Bagetta G, Bernardi G & Corasaniti MT (2007) Early upregulation of matrix metalloproteinases following reperfusion triggers neuroinflammatory mediators in brain ischemia in rat. Int Rev Neurobiol 82, 149169.
  • 98
    Asahi M, Sumii T, Fini ME, Itohara S & Lo EH (2001a) Matrix metalloproteinase-2 gene knock out has no effect on acute brain injury after focal ischemia. NeuroReport 17, 30033007.
  • 99
    Asahi M, Wang X, Mori T, Sumii T, Jung JC, Moskowitz MA, Fini ME & Lo EH (2001b) Effects of matrix metalloproteinase 9 gene knock out on the proteolysis of blood–brain barrier and white matter components after cerebral ischemia. J Neurosci 21, 77247732.
  • 100
    Wang X, Jung JC, Asahi M, Chwang W, Russo L, Moskowitz MA, Dixon CE, Fini E & Lo EH (2000) Effects of matrix metalloproteinase 9 gene knock out on morphological and motor outcomes after traumatic brain injury. J Neurosci 20, 70377042.
  • 101
    Jourquin J, Tremblay E, Decanis N, Charton G, Hanessian S, Chollet AM, Le Diguardher T, Khrestchatiski M & Rivera S (2003) Neuronal activity-dependent increase of net matrix metalloproteinase activity is associated with MMP-9 neurotoxicity after kainate. Eur J Neurosci 18, 15071517.
  • 102
    Copin JC, Goodyear MC, Gidday JM, Shah AR, Gascon E, Dayer A, Morel DM & Gasche Y (2005) Role of matrix metalloproteinases in apoptosis after transient focal cerebral ischemia in rats and mice. Eur J Neurosci 22, 15971608.
  • 103
    Wetzel M, Rosenberg GA & Cunningham LA (2003) Tissue inhibitor of metalloproteinase-3 and matrix metalloproteinase-3 regulate neuronal sensitivity to doxorubicin-induced apoptosis. Eur J Neurosci 18, 10501060.
  • 104
    Lee R, Kermani P, Teng KK & Hempstead BL (2001) Regulation of cell survival by secreted proneurotrophins. Science 294, 19451948.
  • 105
    Zhang K, McQuibban GA, Silva C, Butler GS, Johnston JB, Holden J, Clark-Lewis I, Overall CM & Power C (2003) HIV-induced metalloproteinase processing of the chemokine stromal cell derived factor-1 causes neurodegeneration. Nat Neurosci 6, 10641071.
  • 106
    Schönbeck U, Mach F & Libby P (1998) Generation of biologically active IL-1 beta by matrix metalloproteinases: a novel caspase-1-independent pathway of IL-1 beta processing. J Immunol 161, 33403346.
  • 107
    Zhu W, Khachi S, Hao Q, Shen F, Young WL, Yang GY & Chen Y (2008) Upregulation of EMMPRIN after permanent focal cerebral ischemia. Neurochem Int 52, 10861091.
  • 108
    Zhao BQ, Wang S, Kim HY, Storrie H, Rosen BR, Mooney DJ, Wang X & Lo EH (2006) Role of matrix metalloproteinases in delayed cortical responses after stroke. Nat Med 12, 441445.
  • 109
    Yong VW (2005) Metalloproteinases: mediators of pathology and regeneration in the CNS. Nat Rev Neurosci 6, 931944.
  • 110
    Minami M, Katayama T & Satoh M (2006) Brain cytokines and chemokines: roles in ischemic injury and pain. J Pharmacol Sci 100, 461470.
  • 111
    Allan SM & Rothwell NJ (2001) Cytokines and acute neurodegeneration. Nat Rev Neurosci 2, 734744.
  • 112
    Rothwell N (2003) Interleukin-1 and neuronal injury: mechanisms, modification, and therapeutic potential. Brain Behav Immun 17, 152157.
  • 113
    Liu T, McDonnell PC, Young PR, White RF, Siren AL, Hallenbeck JM, Barone FC & Feurerstein GZ (1993) Interleukin-1-beta messenger RNA expression in ischemic rat cortex. Stroke 24, 17461751.
  • 114
    Buttini M, Sauter A & Boddeke H (1994) Induction of interleukin-1beta mRNA after focal ischemia in the rat. Mol Brain Res 23, 126134.
  • 115
    Davies CA, Loddick SA, Toulmond S, Stroemer RP, Hunt J & Rothwell NJ (1999) The progression and topographic distribution of interleukin-1 beta expression after permanent middle cerebral artery occlusion in the rat. J Cereb Blood Flow Metab 19, 8798.
  • 116
    Legos JJ, Whitmore RG, Erhardt JA, Parsons AA, Tuma RF & Barone FC (2000) Quantitative changes in interleukin proteins following focal stroke in the rat. Neurosci Lett 282, 189192.
  • 117
    Hara H, Friedlander RM, Gagliardini V, Ayata C, Fink K, Huang Z, Shimizu-Sasamata M, Yuan J & Moskowitz MA (1997) Inhibition of interleukin 1β converting enzyme family proteases reduces ischemic and excitotoxic neuronal damage. Proc Natl Acad Sci USA 94, 20072012.
  • 118
    Zhang Z, Chopp M, Goussev A & Powers C (1998a) Cerebral vessels express interleukin 1 beta after focal cerebral ischemia. Brain Res 784, 210217.
  • 119
    Touzani O, Boutin H, Chuquet J & Rothwell N (1999) Potential mechanisms of IL-1 involvement in cerebral ischemia. J Neuroimmunol 100, 203215.
  • 120
    Mabuchi T, Kitagawa K, Ohtsuki T, Kuwabara K, Yagita Y, Yanagihara T, Hori M & Matsumoto M (2000) Contribution of microglia/macrophages to expansion of infarction and response of oligodendrocytes after focal cerebral ischemia in rats. Stroke 31, 17351743.
  • 121
    Irving EA, Barone FC, Reith AD, Hadingham SJ & Parsons AA (2000) Differential activation of MAPK/ERK and p38/SAPK in neurones and glia following focal cerebral ischaemia in the rat. Brain Res 77, 6575.
  • 122
    Walton KM, DiRocco R, Bartlett BA, Koury E, Marcy VR, Jarvis B, Schaefer EM & Bhat RV (1998) Activation of p38MAPK in microglia after ischemia. J Neurochem 70, 17641767.
  • 123
    Barone FC, Irving EA, Ray AM, Lee JC, Kassis S, Kumar S, Badger AM, Legos JJ, Erhardt JA, Ohlstein EH et al. (2001) Inhibition of p38 mitogen-activated protein kinase provides neuroprotection in cerebral focal ischemia. Med Res Rev 21, 129145.
  • 124
    Simi A, Lerouet D, Pinteaux E & Brough D (2007) Mechanisms of regulation for interleukin-1β in neurodegenerative disease. Neuropharmacology 52, 15631569.
  • 125
    Yamasaki Y, Matsuura N, Shizuhara H, Onodera H & Itoyama YKK (1995) Interleukin-1 as a pathogenetic mediator of ischemic brain damage in the rats. Stroke 26, 676681.
  • 126
    Relton JK & Rothwell NJ (1992) Interleukin-1 receptor antagonist inhibits ischaemic and excitotoxic neuronal damage in the rat. Brain Res Bull 29, 242246.
  • 127
    Garcia JH, Liu KF & Relton JK (1995) Interleukin-1 receptor antagonist decreases the number of necrotic neurons in rats with middle cerebral artery occlusion. Am J Pathol 147, 14771486.
  • 128
    Relton JK, Martin D, Thompson RC & Russell DA (1996) Peripheral administration of interleukin-1 receptor antagonist inhibits brain damage after focal cerebral ischemia in the rat. Exp Neurol 138, 206213.
  • 129
    Mulcahy N, Ross J, Rothwell NJ & Loddick SA (2003) Delayed administration of interleukin-1 receptor antagonist protects against transient cerebral ischemia in the rat. Br J Pharmacol 140, 471476.
  • 130
    Wang XK & Feuerstein GZ (1995) Induced expression of adhesion molecules following focal brain ischemia. J Neurotrauma 12, 825832.
  • 131
    Black RA, Kronheim SR, Cantrell M, Deeley MC, March CJ, Prockett KS, Wignall J, Conlon PJ, Cosman D & Hopp TP (1988) Generation of biologically active interleukin-1 beta by proteolytic cleavage of the inactive precursor. J Biol Chem 263, 94379442.
  • 132
    Howard AD, Kostura MJ, Thornberry N, Ding GJF, Limjuco G, Weidner J, Salley JP, Hogquist KA, Chaplin DD, Mumford RA et al. (1991) IL-1-converting enzyme requires aspartic acid residues for processing of the IL-1β precursor at two distinct sites and does not cleave 31 k-Da IL-1α. J Immunol 147, 29642969.
  • 133
    Thornberry NA, Bull HG, Calaycay JR, Chapman KT, Howard AD, Kostura MJ, Miller DK, Molineaux SM, Weidner JR, Aunins J et al. (1992) A novel heterodimeric cysteine protease is required for interleukin-1β processing in monocytes. Nature 356, 768774.
  • 134
    Rabuffetti M, Sciorati C, Tarozzo G, Clementi E, Manfredi AA & Beltramo M (2000) Inhibition of caspase-1-like activity by Ac-Tyr-Val-Ala-Asp-chloromethyl ketone induces long-lasting neuroprotection in cerebral ischemia through apoptosis reduction and decrease of proinflammatory cytokines. J Neurosci 20, 43984404.
  • 135
    Friedlander RM & Yuan J (1998) ICE, neuronal apoptosis and neurodegeneration. Cell Death Diff 5, 823831.
  • 136
    Schielke GP, Yang GY, Shivers BD & Lorris Betz A (1998) Reduced ischemic brain injury in interleukin-1β converting enzyme-deficient mice. J Cereb Blood Flow Metab 18, 180185.
  • 137
    Corasaniti MT, Russo R, Amantea D, Gliozzi M, Siviglia E, Stringaro AR, Malori W, Melino G & Bagetta G (2005) Neuroprotection by the caspase-1 inhibitor Ac-YVAD-(acyloxy)mk in experimental neuroAIDS is independent from IL-1beta generation. Cell Death Differ 12(Suppl. 1), 9991001.
  • 138
    Fantuzzi G, Ku G, Harding MW, Livingston DJ, Sipe JD, Kuida K, Flavell RA & Dinarello CA (1997) Response to local inflammation of IL-1β-converting enzyme-deficient mice. J Immunol 158, 18181824.
  • 139
    Herzog C, Kaushal GP & Haun RS (2005) Generation of biologically active interleukin-1 beta by meprin B. Cytokine 31, 394403.
  • 140
    Pinteaux E, Inoue W, Schmidt L, Molina-Holgado F, Rothwell NJ & Luheshi GN (2007) Leptin induces interleukin-1beta release from rat microglial cells through a caspase 1 independent mechanism. J Neurochem 102, 826833.
  • 141
    Wheeler RD, Boutin H, Touzani O, Luheshi GN, Takeda K & Rothwell NJ (2003) No role for interleukin-18 in acute murine stroke-induced brain injury. J Cereb Blood Flow Metab 23, 531535.
  • 142
    Zaremba J & Losy J (2003) Interleukin-18 in acute ischaemic stroke patients. Neurol Sci 24, 117124.
  • 143
    Yuen CM, Chiu CA, Chang LT, Liou CW, Lu CH, Youssef AA & Yip HK (2007) Level and value of interleukin-18 after acute ischemic stroke. Circ J 71, 16911696.
  • 144
    Gregersen R, Lambertsen K & Finsen B (2000) Microglia and macrophages are the major source of tumor necrosis factor in permanent middle cerebral artery occlusion in mice. J Cereb Blood Flow Metab 20, 5365.
  • 145
    Dziewulska D & Mossakowski MJ (2003) Cellular expression of tumor necrosis factor a and its receptors in human ischemic stroke. Clin Neuropathol 22, 3540.
  • 146
    Yin L, Ohtaki H, Nakamachi T, Dohi K, Iwai Y, Funahashi H, Makino R & Shioda S (2003) Expression of tumor necrosis factor alpha (TNFalpha) following transient cerebral ischemia. Acta Neurochir Suppl 86, 9396.
  • 147
    Offner H, Subramanian S, Parker SM, Afentoulis ME, Vandenbark AA & Hurn PD (2006) Experimental stroke induces massive, rapid activation of the peripheral immune system. J Cereb Blood Flow Metab 26, 654665.
  • 148
    Lambertsen KL, Clausen BH, Fenger C, Wulf H, Owens T, Dagnaes-Hansen F, Meldgaard M & Finsen B (2007) Microglia and macrophages express tumor necrosis factor receptor p75 following middle cerebral artery occlusion in mice. Neuroscience 144, 934949.
  • 149
    Barone FC, Arvin B, White RF, Miller A, Webb CL, Willette RN, Lysko PG & Feuerstein GZ (1997) Tumor necrosis factor-alpha. A mediator of focal ischemic brain injury. Stroke 28, 12331244.
  • 150
    Nawashiro H, Martin D & Hallenbeck JM (1997) Inhibition of tumor necrosis factor and amelioration of brain infarction in mice. J Cereb Blood Flow Metab 17, 229232.
  • 151
    Lavine SD, Hofman FM & Zlokovic BV (1998) Circulating antibody against tumor necrosis factor-alpha protects rat brain from reperfusion injury. J Cereb Blood Flow Metab 18, 5258.
  • 152
    Bruce AJ, Boling W, Kindy MS, Peschon J, Kraemer PJ, Carpenter MK, Holtsberg FW & Mattson MP (1996) Altered neuronal and microglial responses to excitotoxic and ischemic brain injury in mice lacking TNF receptors. Nat Med 2, 788794.
  • 153
    Gary DS, Bruce-Keller AJ, Kindy MS & Mattson MP (1998) Ischemic and excitotoxic brain injury is enhanced in mice lacking the p55 tumor necrosis factor receptor. J Cereb Blood Flow Metab 18, 12831287.
  • 154
    Pradillo JM, Romera C, Hurtado O, Cárdenas A, Moro MA, Leza JC, Dávalos A, Castillo J, Lorenzo P & Lizasoain I (2005) TNFR1 upregulation mediates tolerance after brain ischemic preconditioning. J Cereb Blood Flow Metab 25, 193203.
  • 155
    Hallenbeck JM (2002) The many faces of tumor necrosis factor in stroke. Nat Med 8, 13631368.
  • 156
    Ali C, Nicole O, Docagne F, Lesne S, MacKenzie ET, Nouvelot A, Buisson A & Vivien D (2000) Ischemia-induced interleukin-6 as a potential endogenous neuroprotective cytokine against NMDA receptor-mediated excitotoxicity in the brain. J Cereb Blood Flow Metab 20, 956966.
  • 157
    Berti R, Williams AJ, Moffett JR, Hale SL, Velarde LC, Elliott PJ, Yao C, Dave JR & Tortella FC (2002) Quantitative real-time RT-PCR analysis of inflammatory gene expression associated with ischemia-reperfusion brain injury. J Cereb Blood Flow Metab 22, 10681079.
  • 158
    Block F, Peters M & Nolden-Koch M (2000) Expression of IL-6 in the ischemic penumbra. Neuroreport 11, 963967.
  • 159
    Suzuki S, Tanaka K, Nogawa S, Nagata E, Ito D, Dembo T & Fukuuchi Y (1999) Temporal profile and cellular localization of interleukin-6 protein after focal cerebral ischemia in rats. J Cereb Blood Flow Metab 19, 12561262.
  • 160
    Smith CJ, Emsley HC, Gavin CM, Georgiou RF, Vail A, Barberan EM, del Zoppo GJ, Hallenbeck JM, Rothwell NJ, Hopkins SJ et al. (2004) Peak plasma interleukin-6 and other peripheral markers of inflammation in the first week of ischaemic stroke correlate with brain infarct volume, stroke severity and long-term outcome. BMC Neurol 4, 2.
  • 161
    Waje-Andreassen U, Kråkenes J, Ulvestad E, Thomassen L, Myhr KM, Aarseth J & Vedeler CA (2005) IL-6: an early marker for outcome in acute ischemic stroke. Acta Neurol Scand 111, 360365.
  • 162
    Orion D, Schwammenthal Y, Reshef T, Schwartz R, Tsabari R, Merzeliak O, Chapman J, Mekori YA & Tanne D (2008) Interleukin-6 and soluble intercellular adhesion molecule-1 in acute brain ischaemia. Eur J Neurol 15, 323328.
  • 163
    Emsley HC, Smith CJ, Georgiou RF, Vail A, Hopkins SJ, Rothwell NJ, Tyrrell PJ & Acute Stroke Investigators (2005) A randomised phase II study of interleukin-1 receptor antagonist in acute stroke patients. J Neurol Neurosurg Psychiatry 76, 13661372.
  • 164
    Loddick SA, Turnbull AV & Rothwell NJ (1998) Cerebral interleukin-6 is neuroprotective during permanent focal cerebral ischemia in the rat. J Cereb Blood Flow Metab 18, 176179.
  • 165
    Yamashita T, Sawamoto K, Suzuki S, Suzuki N, Adachi K, Kawase T, Mihara M, Ohsugi Y, Abe K & Okano H (2005) Blockade of interleukin-6 signaling aggravates ischemic cerebral damage in mice: possible involvement of Stat3 activation in the protection of neurons. J Neurochem 94, 459468.
  • 166
    Wang Q, Tang XN & Yenari MA (2007) The inflammatory response in stroke. J Neuroimmunol 184, 5368.
  • 167
    Takami S, Minami M, Nagata I, Namura S & Satoh M (2001) Chemokine receptor antagonist peptide, viral MIP-II, protects the brain against focal cerebral ischemia in mice. J Cereb Blood Flow Metab 21, 14301435.
  • 168
    Minami M & Satoh M (2003) Chemokines and their receptors in the brain: pathophysiological roles in ischemic brain injury. Life Sci 74, 321327.
  • 169
    Yan YP, Sailor KA, Lang BT, Park SW, Vemuganti R & Dempsey RJ (2007) Monocyte chemoattractant protein-1 plays a critical role in neuroblast migration after focal cerebral ischemia. J Cereb Blood Flow Metab 27, 12131224.
  • 170
    Losy J & Zaremba J (2001) Monocyte chemoattractant protein-1 is increased in the cerebrospinal fluid of patients with ischemic stroke. Stroke 32, 26952696.
  • 171
    Chen Y, Hallenbeck JM, Ruetzler C, Bol D, Thomas K, Berman NE & Vogel SN (2003) Overexpression of monocyte chemoattractant protein 1 in the brain exacerbates ischemic brain injury and is associated with recruitment of inflammatory cells. J Cereb Blood Flow Metab 23, 748755.
  • 172
    Hughes PM, Allegrini PR, Rudin M, Perry VH, Mir AK & Wiessner C (2002) Monocyte chemoattractant protein-1 deficiency is protective in a murine stroke model. J Cereb Blood Flow Metab 22, 308317.
  • 173
    Dimitrijevic OB, Stamatovic SM, Keep RF & Andjelkovic AV (2007) Absence of the chemokine receptor CCR2 protects against cerebral ischemia/reperfusion injury in mice. Stroke 38, 13451353.
  • 174
    Robin AM, Zhang ZG, Wang L, Zhang RL, Katakowski M, Zhang L, Wang Y, Zhang C & Chopp M (2006) Stromal cell-derived factor 1 alpha mediates neural progenitor cell motility after focal cerebral ischemia. J Cereb Blood Flow Metab 26, 125134.
  • 175
    Hill WD, Hess DC, Martin-Studdard A, Carothers JJ, Zheng J, Hale D, Maeda M, Fagan SC, Carroll JE & Conway SJ (2004) SDF-1 (CXCL12) is upregulated in the ischemic penumbra following stroke: association with bone marrow cell homing to injury. J Neuropathol Exp Neurol 63, 8496.
  • 176
    Cui X, Chen J, Zacharek A, Li Y, Roberts C, Kapke A, Savant-Bhonsale S & Chopp M (2007) Nitric oxide donor upregulation of stromal cell-derived factor-1/chemokine (CXC motif) receptor 4 enhances bone marrow stromal cell migration into ischemic brain after stroke. Stem Cells 25, 27772785.
  • 177
    Shyu WC, Lin SZ, Yen PS, Su CY, Chen DC, Wang HJ & Li H (2008) Stromal cell-derived factor-1 alpha promotes neuroprotection, angiogenesis, and mobilization/homing of bone marrow-derived cells in stroke rats. J Pharmacol Exp Ther 324, 834849.
  • 178
    Tarozzo G, Campanella M, Ghiani M, Bulfone A & Beltramo M (2002) Expression of fractalkine and its receptor, CX3CR1, in response to ischaemia-reperfusion brain injury in the rat. Eur J Neurosci 15, 16631668.
  • 179
    Soriano SG, Amaravadi LS, Wang YF, Zhou H, Yu GX, Tonra JR, Fairchild-Huntress V, Fang Q, Dunmore JH, Huszar D et al. (2002) Mice deficient in fractalkine are less susceptible to cerebral ischemia-reperfusion injury. J Neuroimmunol 125, 5965.
  • 180
    Clark SR, McMahon CJ, Gueorguieva I, Rowland M, Scarth S, Georgiou R, Tyrrell PJ, Hopkins SJ & Rothwell NJ (2007) Interleukin-1 receptor antagonist penetrates human brain at experimentally therapeutic concentrations. J Cereb Blood Flow Metab 28, 387394.
  • 181
    Gueorguieva I, Clark SR, McMahon CJ, Scarth S, Rothwell NJ, Tyrell PJ, Hopkins SJ & Rowland M (2008) Pharmacokinetic modelling of interleukin-1 receptor antagonist in plasma and cerebrospinal fluid of patients following subarachnoid haemorrhage. Br J Clin Pharmacol 65, 317325.