Nuclear factor-kappaB and cell death after experimental intracerebral hemorrhage in rats

Change of Nrf2 expression in rat hippocampus in a model of chronic cerebral hypoperfusion

Chronic cerebral hypoperfusion (CCH) is common in vascular dementia and Alzheimer's disease. CCH-related oxidative damage plays a significant role in the development of cognitive impairment. Nuclear factor-erythroid 2-related factor-2 (Nrf2) mediates activation of the antioxidant responsive element (ARE)-related gene expression, which is crucial to the endogenous antioxidative system. In this case, we used permanent bilateral occlusion of common carotid arteries (2VO) to mimic CCH. The expression of Nrf2 in different regions of the hippocampus as well as the ability of nuclear Nrf2 and ARE binding have been examined. A phenomenon has been observed that the DNA binding activities were down-regulated. Interestingly, the expression of Nrf2 rose significantly in most regions of rat hippocampus within three weeks after the 2VO surgery. The mismatch might attribute to Nrf2 dysfunction and compensatory synthesis. A conclusion can be drawn that Nrf2 dysfunction is an important factor as a cause of CCH-induced oxidative damage and Nrf2 can be treated as a promising target to alleviate oxidative damage, even cognitive impairment caused by CCH.

Inflammation in intracerebral hemorrhage: from mechanisms to clinical translation

Intracerebral hemorrhage (ICH) accounts for 10-15% of all strokes and is associated with high mortality and morbidity. Currently, no effective medical treatment is available to improve functional outcomes in patients with ICH. Potential therapies targeting secondary brain injury are arousing a great deal of interest in translational studies. Increasing evidence has shown that inflammation is the key contributor of ICH-induced secondary brain injury. Inflammation progresses in response to various stimuli produced after ICH. Hematoma components initiate inflammatory signaling via activation of microglia, subsequently releasing proinflammatory cytokines and chemokines to attract peripheral inflammatory infiltration. Hemoglobin (Hb), heme, and iron released after red blood cell lysis aggravate ICH-induced inflammatory injury. Danger associated molecular patterns such as high mobility group box 1 protein, released from damaged or dead cells, trigger inflammation in the late stage of ICH. Preclinical studies have identified inflammatory signaling pathways that are involved in microglial activation, leukocyte infiltration, toll-like receptor (TLR) activation, and danger associated molecular pattern regulation in ICH. Recent advances in understanding the pathogenesis of ICH-induced inflammatory injury have facilitated the identification of several novel therapeutic targets for the treatment of ICH. This review summarizes recent progress concerning the mechanisms underlying ICH-induced inflammation. We focus on the inflammatory signaling pathways involved in microglial activation and TLR signaling, and explore potential therapeutic interventions by targeting the removal of hematoma components and inhibition of TLR signaling.

New Horizons for Primary Intracerebral Hemorrhage Treatment: Experience From Preclinical Studies

Intracerebral hemorrhage (ICH) remains a major medical problem, for which there is no effective treatment. However, extensive experimental and clinical research carried out in recent years has brought to light new exciting ideas for novel potential treatments. First, it was well documented that the management of hypertension helps to prevent new and recurrent ICH. Also, development of new guidelines for management of hypertension after the onset of the ICH may help in more effective ICH treatment. Existing contemporary data collected from preclinical studies indicates that ICH-induced inflammation represents a key factor leading to secondary brain damage, suggesting that some anti-inflammatory approaches can be used to treat hemorrhagic stroke. In this article, beyond discussing implications related to hypertension, we will summarize important (but not all) new discoveries connecting the role of inflammation to ICH pathology. Selected aspects of inflammatory response including the role of cytokines, transcription factor nuclear factor-kB, microglia activation, astrogliosis, and complement activation will be introduced. We will also discuss the role for reactive oxygen species and metalloproteinases in ICH pathogenesis and introduce basic knowledge on the nature of ICH-induced cell death including apoptosis. Potential targets for intervention and translation will be discussed.

Ethyl pyruvate ameliorates intracerebral hemorrhage-induced brain injury through anti-cell death and anti-inflammatory mechanisms

Ethyl pyruvate (EP) is a pyruvate derivative and known to be cytoprotective in various pathological conditions through anti-cell death and anti-inflammatory mechanisms. The present study investigated the neuroprotective effect of ethyl pyruvate using a mouse model of collagenase-induced intracerebral hemorrhage (ICH). Our results showed that EP treatment to mice reduced brain edema and improved neurological function after ICH. Delayed treatment with EP until 6h after ICH to mice was still neuroprotective. We further demonstrated that EP protected neurons from hemoglobin-induced cell death in vitro and neuronal cell degeneration in ICH mice. Moreover, EP exerted anti-inflammatory effects by inhibiting microglia activation, nuclear factor-κB (NF-κB) DNA binding activity and subsequent downstream pro-inflammatory cytokines (tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β)) production. Taken together, these results suggest that EP exerts neuroprotective effect via anti-cell death and anti-inflammatory actions. EP is a potential novel treatment for ICH patients and deserves further investigation.

TNF-alpha receptor antagonist, R-7050, improves neurological outcomes following intracerebral hemorrhage in mice

Intracerebral hemorrhage (ICH), the most common form of hemorrhagic stroke, exhibits the highest acute mortality and the worst long-term prognosis of all stroke subtypes. Unfortunately, treatment options for ICH are lacking due in part to a lack of feasible therapeutic targets. Inflammatory activation is associated with neurological deficits in pre-clinical ICH models and with patient deterioration after clinical ICH. In the present study, we tested the hypothesis that R-7050, a novel cell permeable triazoloquinoxaline inhibitor of the tumor necrosis factor receptor (TNFR) complex, attenuates neurovascular injury after ICH in mice. Up to 2h post-injury administration of R-7050 significantly reduced blood-brain barrier opening and attenuated edema development at 24h post-ICH. Neurological outcomes were also improved over the first 3 days after injury. In contrast, R-7050 did not reduce hematoma volume, suggesting the beneficial effects of TNFR inhibition were downstream of clot formation/resolution. These data suggest a potential clinical utility for TNFR antagonists as an adjunct therapy to reduce neurological injury and improve patient outcomes after ICH.

Toll-like receptor 4 signaling in intracerebral hemorrhage-induced inflammation and injury

Intracerebral hemorrhage (ICH) is a common type of fatal stroke, accounting for about 15% to 20% of all strokes. Hemorrhagic strokes are associated with high mortality and morbidity, and increasing evidence shows that innate immune responses and inflammatory injury play a critical role in ICH-induced neurological deficits. However, the signaling pathways involved in ICH-induced inflammatory responses remain elusive. Toll-like receptor 4 (TLR4) belongs to a large family of pattern recognition receptors that play a key role in innate immunity and inflammatory responses. In this review, we summarize recent findings concerning the involvement of TLR4 signaling in ICH-induced inflammation and brain injury. We discuss the key mechanisms associated with TLR4 signaling in ICH and explore the potential for therapeutic intervention by targeting TLR4 signaling.

Thrombin and hemin as central factors in the mechanisms of intracerebral hemorrhage-induced secondary brain injury and as potential targets for intervention

Intracerebral hemorrhage (ICH) is a subtype of stoke that may cause significant morbidity and mortality. Brain injury due to ICH initially occurs within the first few hours as a result of mass effect due to hematoma formation. However, there is increasing interest in the mechanisms of secondary brain injury as many patients continue to deteriorate clinically despite no signs of rehemorrhage or hematoma expansion. This continued insult after primary hemorrhage is believed to be mediated by the cytotoxic, excitotoxic, oxidative, and inflammatory effects of intraparenchymal blood. The main factors responsible for this injury are thrombin and erythrocyte contents such as hemoglobin. Therapies including thrombin inhibitors, N-methyl-D-aspartate antagonists, chelators to bind free iron, and antiinflammatory drugs are currently under investigation for reducing this secondary brain injury. This review will discuss the molecular mechanisms of brain injury as a result of intraparenchymal blood, potential targets for therapeutic intervention, and treatment strategies currently in development.

Liraglutide, a long-acting GLP-1 mimetic, and its metabolite attenuate inflammation after intracerebral hemorrhage

The inflammatory response plays a pivotal role in propagating injury of intracerebral hemorrhage (ICH). Glucagon-like-peptide-1 (GLP-1) is a hormone with antidiabetic effect and may also have antiinflammatory properties. Despite consensus that the glucoregulatory action is mediated by the GLP-1 receptor (GLP-1R), mechanisms in the brain remain unclear. We investigated the effect of a long-acting GLP-1 analog, liraglutide, and its truncated metabolite, GLP-1(9-36)a from dipeptidyl peptidase-4 (DPP-4) cleavage in ICH-induced brain injury. Primary outcomes were cerebral edema formation, neurobehavior, and inflammatory parameters. GLP-1(9-36)a, GLP-1R inhibitor, adenosine monophosphate-activated protein kinase (AMPK) phosphorylation inhibitor and DPP-4 inhibitor were administered to examine the mechanisms of action. Liraglutide suppressed neuroinflammation, prevented brain edema and neurologic deficit following ICH, which were partially reversed by GLP-1R inhibitor and AMPK phosphorylation inhibitor. Liraglutide-mediated AMPK phosphorylation was unaffected by GLP-1R inhibitor, and was found to be induced by GLP-1(9-36)a. GLP-1(9-36)a showed salutary effects on primary outcomes that were reversed by AMPK phosphorylation inhibitor but not by GLP-1R inhibitor. Liraglutide and DPP-4 inhibitor co-administration reversed liraglutide-mediated AMPK phosphorylation and antiinflammatory effects. Liraglutide exerted duals actions and the antiinflammatory effects are partially mediated by its metabolite in a phosphorylated AMPK-dependent manner. Therapies that inhibit GLP-1 degradation may weaken the metabolite-mediated effects.

Putative role of prostaglandin receptor in intracerebral hemorrhage

Each year, approximately 795,000 people experience a new or recurrent stroke. Of all strokes, 84% are ischemic, 13% are intracerebral hemorrhage (ICH) strokes, and 3% are subarachnoid hemorrhage strokes. Despite the decreased incidence of ischemic stroke, there has been no change in the incidence of hemorrhagic stroke in the last decade. ICH is a devastating disease 37–38% of patients between the ages of 45 and 64 die within 30 days. In an effort to prevent ischemic and hemorrhagic strokes we and others have been studying the role of prostaglandins and their receptors. Prostaglandins are bioactive lipids derived from the metabolism of arachidonic acid. They sustain homeostatic functions and mediate pathogenic mechanisms, including the inflammatory response. Most prostaglandins are produced from specific enzymes and act upon cells via distinct G-protein coupled receptors. The presence of multiple prostaglandin receptors cross-reactivity and coupling to different signal transduction pathways allow differentiated cells to respond to prostaglandins in a unique manner. Due to the number of prostaglandin receptors, prostaglandin-dependent signaling can function either to promote neuronal survival or injury following acute excitotoxicity, hypoxia, and stress induced by ICH. To better understand the mechanisms of neuronal survival and neurotoxicity mediated by prostaglandin receptors, it is essential to understand downstream signaling. Several groups including ours have discovered unique roles for prostaglandin receptors in rodent models of ischemic stroke, excitotoxicity, and Alzheimer disease, highlighting the emerging role of prostaglandin receptor signaling in hemorrhagic stroke with a focus on cyclic-adenosine monophosphate and calcium (Ca²⁺) signaling. We review current ICH data and discuss future directions notably on prostaglandin receptors, which may lead to the development of unique therapeutic targets against hemorrhagic stroke and brain injuries alike.

The protective role of oxymatrine on neuronal cell apoptosis in the hemorrhagic rat brain

ETHNOPHARMACOLOGICAL RELEVANCE

Oxymatrine is extracted from the traditional Chinese herb Sophora flavescens Ait, possesses anti-inflammatory, anti-oxidative and anti-apoptotic properties, and has been used for the treatment of chronic viral hepatitis and many other diseases.

AIMS OF THE STUDY

This study aimed to investigate the effects of oxymatrine on inflammatory response mediated by Toll-like receptor4 (TLR4) and nuclear factor kappa-B (NF-κB), oxidative injury induced by 12/15 lipoxygenase (12/15-LOX), phosphorylated p38 mitogen activated protein kinase (phosphor-p38 MAPK) and cytosolic phospholipase A2 (cPLA2), and neuronal cell apoptosis in rat brain with intracerebral hemorrhage (ICH).

MATERIALS AND METHODS

Wistar rats were treated intraperitoneally with 60 or 120mg/kg of oxymatrine daily for 5 days following ICH. The rats were sacrificed at hour 2, 6, 12, 24, 48, 72, and 120 after ICH. The gene expressions of TLR-4 and NF-κB, the levels of TNF-alpha, interleukin-1beta, interleukin-6, 12/15-LOX, phospho-p38 MAPK and cPLA2, and the number of apoptotic neuronal cells in rat brain were determined.

RESULTS

Oxymatrine at 120mg/kg significantly suppressed gene expressions of TLR-4 and NF-κB, decreased levels of TNF-alpha, interleukin-1beta and interleukin-6, inhibited synthesis of 12/15-LOX, phospho-p38 MAPK and cPLA2 protein, and mitigated apoptotic neuronal changes following ICH in rat.

CONCLUSION

Oxymatrine at 120mg/kg following ICH inhibits inflammatory responses, oxidative injury, and neuronal cell apoptosis in rats.

Microglial cell activation is a source of metalloproteinase generation during hemorrhagic transformation

Hemorrhage and edema accompany evolving brain tissue injury after ischemic stroke. In patients, these events have been associated with metalloproteinase (MMP)-9 in plasma. Both the causes and cellular sources of MMP-9 generation in this setting have not been defined. MMP-2 and MMP-9 in nonhuman primate tissue in regions of plasma leakage, and primary murine microglia and astrocytes, were assayed by immunocytochemistry, zymography, and real-time RT-PCR. Ischemia-related hemorrhage was associated with microglial activation in vivo, and with the leakage of plasma fibronectin and vitronectin into the surrounding tissue. In strict serum-depleted primary cultures, by zymography, pro-MMP-9 was generated by primary murine microglia when exposed to vitronectin and fibronectin. Protease secretion was enhanced by experimental ischemia (oxygen-glucose deprivation, OGD). Primary astrocytes, on each matrix, generated only pro-MMP-2, which decreased during OGD. Microglia-astrocyte contact enhanced pro-MMP-9 generation in a cell density-dependent manner under normoxia and OGD. Compatible with observations in a high quality model of focal cerebral ischemia, microglia, but not astrocytes, respond to vitronectin and fibronectin, found when plasma extravasates into the injured region. Astrocytes alone do not generate pro-MMP-9. These events explain the appearance of MMP-9 antigen in association with ischemia-induced cerebral hemorrhage and edema.

The Molecular Mechanisms that Promote Edema After Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a devastating type of stroke with no effective therapies. Clinical advances in ICH treatment are limited by an incomplete understanding of the molecular mechanisms responsible for secondary injury and poor outcome. Increasing evidence suggests that cerebral edema is a major contributor to secondary injury and poor outcome in ICH. ICH activates specific signaling pathways that promote edema and damage neuronal tissue. By increasing our understanding of these pathways, we may be able to target them pharmaceutically to reduce edema in ICH patients. In this review, we focus on three major signaling pathways that promote edema after ICH: (1) the coagulation cascade and thrombin, (2) the inflammatory response and matrix metalloproteinases, and (3) the complement cascade and hemoglobin toxicity. We will describe the experimental evidence that confirms these pathways promote edema in ICH, discuss potential targets for new therapies, and comment on important directions for future research.

Age-related comparisons of evolution of the inflammatory response after intracerebral hemorrhage in rats

In the hours to days after intracerebral hemorrhage (ICH), there is an inflammatory response within the brain characterized by the infiltration of peripheral neutrophils and macrophages and the activation of brain-resident microglia and astrocytes. Despite the strong correlation of aging and ICH incidence, and increasing information about cellular responses, little is known about the temporal- and age-related molecular responses of the brain after ICH. Here, we monitored a panel of 27 genes at 6 h and 1, 3, and 7 days after ICH was induced by injecting collagenase into the striatum of young adult and aged rats. Several molecules (CR3, TLR2, TLR4, IL-1β, TNFα, iNOS, IL-6) were selected to reflect the classical activation of innate immune cells (macrophages, microglia) and the potential to exacerbate inflammation and damage brain cells. Most of the others are associated with the resolution of innate inflammation, alternative pathways of macrophage/microglial activation, and the repair phase after acute injury (TGFβ, IL-1ra, IL-1r2, IL-4, IL-13, IL-4Rα, IL-13Rα1, IL-13Rα2, MRC1, ARG1, CD163, CCL22). In young animals, the up-regulation of 26 in 27 genes (not IL-4) was detected within the first week. Differences in timing or levels between young and aged animals were detected for 18 of 27 genes examined (TLR2, GFAP, IL-1β, IL-1ra, IL-1r2, iNOS, IL-6, TGFβ, MMP9, MMP12, IL-13, IL-4Rα, IL-13Rα1, IL-13Rα2, MRC1, ARG1, CD163, CCL22), with a generally less pronounced or delayed inflammatory response in the aged animals. Importantly, within this complex response to experimental ICH, the induction of pro-inflammatory, potentially harmful mediators often coincided with resolving and beneficial molecules.

Proteasome Inhibitor Reduces Astrocytic iNOS Expression and Functional Deficit after Experimental Intracerebral Hemorrhage in Rats

Intracerebral hemorrhage (ICH) is associated with perihematoma inflammation and edema. We have recently shown cell death and a robust activation of the proinflammatory transcription factor, nuclear factor-κB (NF-κB) in brain areas adjacent to the hematoma. Proteasome represents a key component necessary for the activation of NF-κB. The aim of our present study was to examine if selective proteasome inhibition with a clinically relevant agent, PS-519, might influence the ICH pathogenesis, and improve functional outcome. ICH was induced in Sprague-Dawley rats by the double blood injection method. PS-519 was administered intravenously 4 h and 15 min after induction of ICH. Behavioral testing was performed 3, 5, and 7 days later. The animals were sacrificed on day 7, and their brains were evaluated for hemorrhage size and inflammation using immunohistochemistry with antibody to various inflammatory markers. Treatment with PS-519 significantly (p < 0.05) reduced behavioral impairment post-ICH as determined by the footfault test. This effect was not due to difference in ICH volume. The improved functional status of PS-519 treated animals correlated positively (p < 0.01) with reduced expression of astroglial iNOS in areas adjacent to the hemorrhage 7 days post-ICH. No delayed changes in expression of OX-42 and ED-1 (microglia/macrophages marker), or vimentin (intermediate filament; marker of astroglia activation) were detected in animals treated with PS-519. This data suggests that modulation of proteasome-activated processes may represent a strategic target for treatment of ICH in humans.

Ginkgolide B reduces neuronal cell apoptosis in the hemorrhagic rat brain: possible involvement of Toll-like receptor 4/nuclear factor-kappa B pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Ginkgolide B (GB) is one of the ginkgolides that have been isolated from leaves and root bark of the Chinese tree Ginkgo biloba L. (Ginkgoaceae), and is a specific and potent antagonist of platelet activating factor. There is a large body of data showing that GB possesses a markedly neuroprotective property against ischemia-induced impairment in vivo and in vitro. Recently it has been found that GB can inhibit the inflammation in the rat brain tissues with ischemia/reperfusion injury and in the astrocytes treated with lipopolysaccharide, as well as protect neurons against beta-amyloid 25-35 and ischemia-induced apoptosis. However, there have been few reports on the influence of GB on intracerebral hemorrhage (ICH). This study was to investigate the effects of intraperitoneal GB on neuronal cell apoptosis, inflammatory cytokines and Toll-like receptor 4 (TLR4)/nuclear factor kappa-B (NF-κB) pathway after ICH.

MATERIALS AND METHODS

Wistar rats obtained an intraperitoneal injection of 5, 10 and 20mg/kg GB after ICH once a day till day 5. Rats were sacrificed by decapitation at hour 2, 6 and 12, as well as day 1, 2, 3 and 5 after ICH. Gene expressions of TLR-4 and NF-κB, concentrations of tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β) and interleukin-6 (IL-6) as well as number of apoptotic neuronal cells in hemorrhagic rat brain tissues were determined.

RESULTS

The administration of 10 and 20mg/kg GB could significantly suppress gene expressions of TLR-4 and NF-κB, lessen concentrations of TNF-α, IL-1β and IL-6 as well as reduce number of apoptotic neuronal cells in hemorrhagic rat brain tissues by Least-significant Difference test (P<0.05), but the administration of 5mg/kg GB not (P>0.05). However, a clear concentration-response relationship was not found.

CONCLUSIONS

GB may inhibit TLR4/NF-κB-dependent inflammatory responses, and furthermore lessen neuronal cell apoptosis after ICH, which may support the use of G. biloba extracts for the treatment of ICH.

Treatment targets in intracerebral hemorrhage

Intracerebral hemorrhage (ICH) imparts a higher mortality and morbidity than ischemic stroke. The therapeutic interventions that are currently available focus mainly on supportive care and secondary prevention. There is a paucity of evidence to support any one acute intervention that improves functional outcome. This chapter highlights current treatment targets for ICH based on the pathophysiology of the disease.

Molecular pathophysiology of cerebral hemorrhage: secondary brain injury

Intracerebral hemorrhage (ICH) is an often fatal type of stroke that kills approximately 30,000 people annually in the United States. If the patient survives the ictus, then the resulting hematoma within brain parenchyma triggers a series of adverse events causing secondary insults and severe neurological deficits. This article discusses selected aspects of secondary brain injury after ICH and outlines key mechanisms associated with hematoma toxicity, oxidative stress, and inflammation. Finally, this review discusses the relevance of hematoma resolution processes as a target for ICH therapy and presents potential clinically relevant molecular targets that could be harnessed to treat secondary injury associated with ICH injury.

Attenuation of hematoma size and neurological injury with curcumin following intracerebral hemorrhage in mice

OBJECT

Intracerebral hemorrhage (ICH) is associated with significant morbidity and mortality. Acute hematoma enlargement is an important predictor of neurological injury and poor clinical prognosis; but neurosurgical clot evacuation may not be feasible in all patients and treatment options remain largely supportive. Thus, novel therapeutic approaches to promote hematoma resolution are needed. In the present study, the authors investigated whether the curry spice curcumin limited neurovascular injury following ICH in mice.

METHODS

Intracerebral hemorrhage was induced in adult male CD-1 mice by intracerebral administration of collagenase or autologous blood. Clinically relevant doses of curcumin (75-300 mg/kg) were administered up to 6 hours after ICH, and hematoma volume, inflammatory gene expression, blood-brain barrier permeability, and brain edema were assessed over the first 72 hours. Neurological assessments were performed to correlate neurovascular protection with functional outcomes.

RESULTS

Curcumin increased hematoma resolution at 72 hours post-ICH. This effect was associated with a significant reduction in the expression of the proinflammatory mediators, tumor necrosis factor-α, interleukin-6, and interleukin-1β. Curcumin also reduced disruption of the blood-brain barrier and attenuated the formation of vasogenic edema following ICH. Consistent with the reduction in neuroinflammation and neurovascular injury, curcumin significantly improved neurological outcome scores after ICH.

CONCLUSIONS

Curcumin promoted hematoma resolution and limited neurological injury following ICH. These data may indicate clinical utility for curcumin as an adjunct therapy to reduce brain injury and improve patient outcome.

Astrocyte-derived glutathione attenuates hemin-induced apoptosis in cerebral microvascular cells

Intracerebral hemorrhage (ICH) induces neurovascular injury via poorly defined mechanisms. The aim of this study was to determine whether gliovascular communication may restrict hemorrhagic vascular injury. Hemin, a hemoglobin by-product, concentration- and time-dependently increased apoptotic cell death in mouse bEnd.3 cells and in primary human brain microvascular endothelial cells, at least in part, via a caspase-3 dependent pathway. Cell death was preceded by a NFκB-mediated increase in inflammatory gene expression, including upregulation of inducible nitric oxide synthase (iNOS) expression and activity. Functionally, inhibition of iNOS or the addition of a peroxynitrite decomposition catalyst reduced cell death. Interestingly, co-treatment with astrocyte-conditioned media (ACM) reversed hemin-induced NFκB activation, nitrotyrosine formation, and apoptotic cell death, at least in part, via the release of the endogenous antioxidant, reduced glutathione (GSH). Prior treatment of astrocytes with the GSH-depleting agent, DL-buthionine (S,R)-sulfoximine or direct addition of diethyl maleate, a thiol-depleting agent, to ACM reversed the observed protection. In contrast, neither exogenous GSH nor the GSH precursor, N-acetylcysteine, was protective in bEnd.3 cells. Together, these data support an important role for astrocyte-derived GSH in the maintenance of oxidative balance in the vasculature and suggest therapeutic targeting of the GSH system may reduce neurological injury following ICH.

FTY720 is neuroprotective and improves functional outcomes after intracerebral hemorrhage in mice

Intracerebral hemorrhage (ICH) accounts for 20% of all strokes and is the most devastating form across all stroke types. Lymphocytes have been shown to potentiate cerebral inflammation and brain injury after stroke. FTY720 (Fingolimod) is an immune-modulating drug that prevents the egress of peripheral lymphocytes from peripheral stores. We hypothesized that FTY720 would reduce peripheral circulating lymphocytes, resulting in reduced brain injury and improved functional outcomes. CD-1 mice were anesthetized and then injected with collagenase into the right basal ganglia. Animals were divided into three groups: sham, ICH+Vehicle, and ICH+FTY720, by the intra-peritoneal route at 1 h after ICH induction. Brain water content was measured at 24 and 72 h. Neurobehavioral tests included corner test, forelimb use asymmetry, paw placement, wire-hang test, beam balance test, and a Neuroscore. FTY720 significantly reduced brain edema and improved neurological function at all time points tested. Lymphocyte modulation with FTY720 is an effective neuroprotective strategy to reduce brain injury and promote functional recovery after ICH.

Hemoglobin-induced oxidative stress contributes to matrix metalloproteinase activation and blood-brain barrier dysfunction in vivo

Hemoglobin (Hb) released from extravasated erythrocytes is implicated in brain edema after intracerebral hemorrhage (ICH). Hemoglobin is a major component of blood and a potent mediator of oxidative stress after ICH. Oxidative stress and matrix metalloproteinases (MMPs) are associated with blood-brain barrier (BBB) dysfunction. This study was designed to elucidate whether Hb-induced oxidative stress contributes to MMP-9 activation and BBB dysfunction in vivo. An intracerebral injection of Hb into rat striata induced increased hydroethidine (HEt) signals in parallel with MMP-9 levels. In situ gelatinolytic activity colocalized with oxidized HEt signals in vessel walls, accompanied by immunoglobulin G leakage and a decrease in immunoactivity of endothelial barrier antigen, a marker of endothelial integrity. Administration of a nonselective MMP inhibitor prevented MMP-9 levels and albumin leakage in injured striata. Moreover, reduction in oxidative stress by copper/zinc-superoxide dismutase (SOD1) overexpression reduced oxidative stress, MMP-9 levels, albumin leakage, and subsequent apoptosis compared with wild-type littermates. We speculate that Hb-induced oxidative stress may contribute to early BBB dysfunction and subsequent apoptosis, partly through MMP activation, and that SOD1 overexpression may reduce Hb-induced oxidative stress, BBB dysfunction, and apoptotic cell death.

Relationship between leukocyte kinetics and behavioral tests changes in the inflammatory process of hemorrhagic stroke recovery

In this study, we investigated the inflammatory response to hemorrhagic stroke (HS) as the main mechanism of brain functional recovery. Sprague-Dawley rats (n = 24) underwent surgery with sterile saline (control group, n = 12) and collagenase IV-S (stroke group, n = 12) being injected into the right striatum. White blood cell analysis, histological and immunohistological examination of the brain slices, as well as densitometric analysis of polymorphonuclear and microglial cells/macrophages were correlated with behavioral tests, and the data were subjected to appropriate statistical processing. The results indicate a strong correlation between polymorphonuclear and mononuclear changes in the blood and the zone of hemorrhagic stroke with behavioral tests of functional brain recovery. We propose that the inflammatory response is determined by kinetics of polymorphonuclear and mononuclear cells in both the blood and the hemorrhagic stroke zone. Kinetics of these cells is followed by the restoration of functions, and the maximum functional recovery is observed by the time polymorphonuclear and mononuclear stages have completed. With the development of inflammation and leukocyte kinetics, it is possible to predict functional recovery of hemorrhagic stroke. Improvement of the degree and rate of hemorrhagic stroke functional recovery may be achieved by therapeutic interventions into the inflammatory mechanisms influencing polymorphonuclear and mononuclear cell kinetics.

Erythropoietin in combination of tissue plasminogen activator exacerbates brain hemorrhage when treatment is initiated 6 hours after stroke

BACKGROUND AND PURPOSE

Erythropoietin (EPO), a hematopoietic cytokine, exerts neuroprotective effects in experimental stroke. In the present study, we investigated the effect of recombinant human EPO (rhEPO) in combination with tissue plasminogen activator (tPA) on embolic stroke.

METHODS

Rats subjected to embolic middle cerebral artery occlusion (MCAO) were treated with rhEPO (5000 U/kg) in combination with tPA (10 mg/kg) at 2 or 6 hours after MCAO. Control groups consisted of ischemic rats treated with rhEPO (5000 U/kg) alone, tPA (10 mg/kg) alone, or saline at 2 or 6 hours after MCAO.

RESULTS

The combination therapy of rhEPO and tPA initiated 6 hours after MCAO did not reduce the ischemic lesion volume and significantly (P<0.05) increased the incidence of brain hemorrhage measured by frequency of gross hemorrhage and a quantitative spectrophotometric hemoglobin assay compared with rats treated with rhEPO alone and tPA alone. However, when the combination therapy was initiated 2 hours after MCAO, the treatment significantly (P<0.05) reduced the lesion volume and did not substantially increase the incidence of hemorrhagic transformation compared with saline-treated rats. Immunostaining analysis revealed that the combination therapy of rhEPO and tPA at 6 hours significantly (P<0.05) increased matrix metalloproteinase-9, NF-kappaB, and interleukin-1 receptor-associated kinase-1 immunoreactive cerebral vessels compared with rats treated with rhEPO alone and saline.

CONCLUSIONS

EPO exacerbates tPA-induced brain hemorrhage without reduction of ischemic brain damage when administered 6 hours after stroke in a rat model of embolic MCAO and that matrix metalloproteinase-9, NF-kappaB, and interleukin-1 receptor-associated kinase-1 upregulated by the delayed combination therapy may contribute to augmentation of brain hemorrhage.

Dynamic changes of inflammatory markers in brain after hemorrhagic stroke in humans: a postmortem study

This histopathologic case-control study was designed to characterize the dynamic changes in protein expression of nuclear factor-kappa B (NF-kappaB)/p65 subunit, macrophage inflammatory protein-2 (MIP-2), and matrix metalloproteinase-9 (MMP-9) in postmortem brains of patients with and without intracerebral hemorrhage (ICH). Thirty-six human brains from patients with ICH and six control brains were included in this study. We found that expression levels of NF-kappaB/p65, MIP-2, and MMP-9 were each upregulated on the injured side of the hippocampus at times ranging from 2h to 5days post-ICH. Interestingly, the expression of all three markers was also upregulated on the uninjured side of the hippocampus and in the cerebellum, although to a lesser extent. These data suggest that inflammation occurs early and persists for several days after ICH in humans and could be involved in the progression of ICH-induced secondary brain damage.

Activation of TLR4-mediated NFkappaB signaling in hemorrhagic brain in rats

Inflammation and immunity play a crucial role in the pathogenesis of Intracerebral hemorrhage (ICH). Toll-like receptor 4- (TLR4-) mediated nuclear factor kappa-B (NFκB) signaling plays critical roles in the activation and regulation of inflammatory responses in injured brain. However, the involvement of TLR4-mediated NFκB signaling in the pathogenesis of ICH remains unknown. The present study was to evaluate the temporal profile of the expression of TLR4 and the activation of TLR4-mediated NFκB signaling in brain tissues of Wistar rats after ICH. TLR4 mRNA and protein, the phosphorylation of inhibitors of kappa B (p-IκBα), and the activity of NFκB were examined in hemorrhagic cerebral tissue by Rt-PCR, Western blots, immunohistochemistry staining, and EMSA. Compared with saline control, the TLR4 mRNA and protein significantly increased starting at 6 hours after ICH, peaked on the 3rd day after ICH, and then decreased but still maintained at a higher level on the 7th day after ICH (P < .05). The level of p-IκBα and the activity of NFκB also increased in the brain after ICH compared with saline control. The present study firstly suggests that TLR4-mediated NFκB signaling participates in the pathogenesis of ICH, which may become a therapeutic target for ICH-induced brain damage.

Decreased brain edema after collagenase-induced intracerebral hemorrhage in mice lacking the inducible nitric oxide synthase gene. Laboratory investigation

OBJECT

Hematoma size and brain edema after intracerebral hemorrhage (ICH) are important prognostic factors. Inducible nitric oxide synthase (iNOS) is induced after cerebral ischemia and is known to be involved in secondary neuronal injury, but its significance in ICH is unknown. The authors tested whether iNOS would influence hematoma size and brain edema after ICH.

METHODS

The authors used C57BL/6 and iNOS knockout mice for all the experiments. Experimental ICH was induced by the intrastriatal stereotactic administration of bacterial collagenase. Brain tissue was obtained at 72 hours after ICH. The volume of hematoma was quantified by spectrophotometric assay, and the brain water content was measured. The investigators also measured blood-brain barrier permeability using Evans blue dye.

RESULTS

There was no significant difference in hematoma size between the 2 groups. The brain water content of the lesional hemisphere was higher in C57BL/6 mice than in iNOS knockout mice. More Evans blue leakage in the brain was observed in C57BL/6 control mice than in iNOS knockout mice. Immunohistochemistry showed iNOS immunoreactivity in the perihematoma areas of C57BL/6 mice but not in the iNOS knockout mice.

CONCLUSIONS

When hematoma size was similar, iNOS knockout mice had significantly less brain edema than their littermates. These results suggest that iNOS modulation might become an antiedematous therapy for ICH.

Tissue inhibitor of matrix metalloproteinases-3 (TIMP-3) lacks involvement in bacterial collagenase-induced intracerebral hemorrhage in mouse

Intracerebral hemorrhage (ICH) leads to delayed cell death in the regions around the hemorrhagic mass. Apoptosis has been identified in the dying cells, but the mechanism involved is unclear. Others and us have shown that matrix metalloproteinases (MMPs) are increased in ICH and could directly contribute to cell death. Tissue inhibitor to metalloproteinases-3 (TIMP-3) facilitates apoptosis in cancer cells and neurons by inhibiting the shedding of tumor necrosis factor-alpha (TNF-alpha) death receptors, Fas and p55TNF receptor 1, by MMP-3 and TNF-alpha converting enzyme (TACE), respectively. Therefore, TIMP-3 may contribute to cell death in ICH. We adapted the bacterial collagenase-induced hemorrhage (CIH) model to the mouse. Adult C57Bl/6 and Timp-3 knockout mice had CIH. Expression of mRNA for TIMP-3 was determined by real-time PCR. Hemorrhage volume and numbers of apoptotic cells were measured by unbiased stereology. Timp-3 mRNA was similar in the knockout and wild-type mice prior to injury and induction of CIH failed to cause an increase in Timp-3 mRNA in the wild-type. Furthermore, there were no differences found in the hemorrhage size or in the numbers of apoptotic cells between the Timp-3 knockout or wild-type. We were unable to prove the hypothesis that TIMP-3 is involved cell death in CIH in the mouse.

Preclinical models of intracerebral hemorrhage: a translational perspective

Intracerebral hemorrhage (ICH) is a devastating and relatively common disease affecting as many as 50,000 people annually in the United States alone. ICH remains associated with poor outcome, and approximately 40-50% of afflicted patients will die within 30 days. In reports from the NIH and AHA, the importance of developing clinically relevant models of ICH that will extend our understanding of the pathophysiology of the disease and target new therapeutic approaches was emphasized. Traditionally, preclinical ICH research has most commonly utilized two paradigms: clostridial collagenase-induced hemorrhage and autologous blood injection. In this article, the use of various species is examined in the context of the different model types for ICH, and a mechanistic approach is considered in evaluating the numerous breakthroughs in our current fund of knowledge. Each of the model types has its inherent strengths and weaknesses and has the potential to further our understanding of the pathophysiology and treatment of ICH. In particular, transgenic rodent models may be helpful in addressing genetic influences on recovery from ICH.

Hemin-induced necroptosis involves glutathione depletion in mouse astrocytes

Intracerebral hemorrhage (ICH) is a devastating neurological injury associated with significant mortality. Astrocytic inflammation may contribute to the pathogenesis of ICH, although the underlying cellular mechanisms remain unclear. In this study, the hemoglobin oxidation by-product, hemin, concentration dependently induced necroptotic cell death in cortical astrocytes within 5 h of treatment. Hemin-induced cell death was preceded by increased inflammatory gene expression (COX-2, IL-1beta, TNF-alpha, iNOS). Inhibition of the NF-kappaB transcription factor reversed inflammatory gene expression and attenuated cell death after hemin treatment, suggesting a possible role for inflammatory mediators in astrocytic injury. Superoxide production paralleled the increase in iNOS expression, and inhibition of either iNOS (aminoguanidine or iminopiperdine) or superoxide (apocynin) significantly reduced cell death. Similarly, reduced formation of peroxynitrite, the damaging product of nitric oxide and superoxide, significantly reduced hemin injury. Hemin-induced peroxidative injury was associated with a rapid depletion of intracellular glutathione (GSH), culminating in lipid peroxidation and cell death, effects that were reduced by cotreatment with exogenous GSH, N-acetyl-L-cysteine, or the glutathione peroxidase mimetic ebselen. Together, these studies suggest a novel role for GSH depletion in necroptotic astrocyte injury after a hemorrhagic injury and indicate that therapeutic targeting of GSH may exert a beneficial effect after ICH.

The profile of gene expression and role of nuclear factor kappa B on glomerular injury in rats with Thy-1 nephritis

Mesangioproliferative glomerulonephritis (MsPGN) is a disease of high incidence in humans. Rats with Thy-1 nephritis (Thy-1 N) are used as an animal model for studying MsPGN. Although several studies have demonstrated that many pathological factors could cause the injury of glomerular mesangial cells (GMCs) in Thy-1 N, changes of profile and the molecular mechanism of the disease (i.e. the role of transcription factors) at intervals remain unclear. The purpose of this study was to identify the changes in gene expression profile and to observe the role of nuclear factor kappa B (NF-kappaB) on the pathological change of renal tissue in Thy-1 N rats. Our results showed that the pathological changes of GMCs in Thy-1 N included three phases: apoptosis (40 min), necrosis (24 h) and proliferation (7 days). Concomitantly, at 40 min and on day 7, the up-regulation of 341 genes and 250 genes were observed, while 392 genes and 119 genes were down-regulated in Thy-1 N. Expression of interleukin (IL)-1beta, IL-6, proliferating cell nuclear antigen, alpha-smooth muscle actin, collagen type IV and excretion of urinary protein was increased in rats with Thy-1 N and decreased in pyrrolidine dithiocarbamate-treated rats with Thy-1 N. These data indicated that the significant changes in the gene profile were coupled with the pathological changes of Thy-1 N, and activation of NF-kappaB may contribute to the pathogenesis of GMCs apoptosis, proliferation, extracelluar matrix accumulation and proteinuria in Thy-1 N.

Matrix metalloproteinase inhibition facilitates cell death in intracerebral hemorrhage in mouse

Intracerebral hemorrhage (ICH) initiates an inflammatory response with secondary growth of hemorrhage and cell death. Matrix metalloproteinase (MMP) gelatinolytic activity is increased in ICH, and synthetic inhibitors to MMPs reduce edema and hemorrhage size. Recently, we found that tissue inhibitor of metalloproteinase-3 (TIMP-3) is elevated after ischemia and colocalizes with TUNEL (terminal deoxynucleotidyl transferase-mediated 2'-deoxyuridine 5'-triphosphate-biotin nick end-labeled)-labeled cells. Tissue inhibitor of metalloproteinase-3 promotes neuronal apoptosis in vitro by blocking the shedding of the tumor necrosis factor (TNF) superfamily of death receptors/ligands by stromelysin-1 (MMP-3). However, the effect of TIMP-3 and synthetic MMP inhibitors on cell death in ICH is unclear. Therefore, we used the collagenase-induced intracerebral hemorrhage (CIH) model in Timp-3 knockout and C57Bl/6 wild-type mice to study MMP expression, hemorrhage volume, and cell death. Real-time PCR showed an increase in Mmp-3 mRNA in CIH, but similar Mmp-2 and -9 mRNA expression levels in CIH and saline-injected mice. Protein levels of pro and cleaved MMP-3 were increased in CIH, and zymographic gelatinolytic activity of MMP-9 was elevated after CIH at 72 h, suggesting an exogenous source. Apoptosis was shown by increased caspase-3 levels at 2 and 72 h, and active caspase-8 by 2 and 24 h. The Timp-3 null mouse and wild types had similar hemorrhage sizes and TUNEL-labeled cells. Unexpectedly, the broad-spectrum MMP inhibitor BB-94 increased hemorrhage size and TUNEL-labeled cells. Our results fail to implicate TIMP-3 in apoptosis in CIH, but show that BB-94 increased apoptosis in CIH, possibly by blocking shedding of TNF death receptors and/or their ligands.

PKB/Akt inhibits ceramide-induced apoptosis in neuroblastoma cells by blocking apoptosis-inducing factor (AIF) translocation

Ceramide is a sphingolipid that is abundant in the plasma membrane of neuronal cells and is thought to have regulatory roles in cell differentiation and cell death. Ceramide is known to induce apoptosis in a variety of different cell types, whereas the physiological significance of gangliosides, another class of sphingolipids, in these processes is still unclear. We examined the mechanisms of ceramide-induced cell death using a human neuroblastoma cell line. Treatment of the human neuroblastoma cell line SH-SY5Y with ceramide induced dephosphorylation of the PKB/Akt kinase and subsequent mitochondrial dysfunction. In addition, ceramide-induced neuronal cell death was not completely blocked by inhibition of caspase activity. This incomplete inhibition appeared to be attributable to the translocation of apoptosis-inducing factor to the nucleus. Furthermore, overexpression of active PKB/Akt or Bcl-2 successfully blocked ceramide-induced neuronal cell death through inhibition of the translocation of apoptosis-inducing factor.

Stroke in the immature brain: review of pathophysiology and animal models of pediatric stroke

Pediatric stroke research presents many challenges. Relatively low incidence, need for age stratification, diverse etiologies, delays in diagnosis, lack of an established age-based stroke severity scale and outcome measures are only some of the issues that have prevented the implementation of clinical trials in infants and children with stroke. Experimental animal models of pediatric stroke, therefore, are critical to understanding the pathophysiology and management of ischemic brain damage in the immature brain, and provide the necessary platform for future clinical trials. In this review we discuss the pertinent clinical aspects of pediatric stroke, the pathophysiology of stroke in the developing brain and the animal models established to study basic mechanisms as well as translational issues in pediatric stroke.

A mouse model of intracerebral hemorrhage using autologous blood infusion

The development of controllable and reproducible animal models of intracerebral hemorrhage (ICH) is essential for the systematic study of the pathophysiology and treatment of hemorrhagic stroke. In recent years, we have used a modified version of a murine ICH model to inject blood into mouse basal ganglia. According to our protocol, autologous blood is stereotactically infused in two stages into the right striatum to mimic the natural events of hemorrhagic stroke. Following ICH induction, animals demonstrate reproducible hematomas, brain edema formation and marked neurological deficits. Our technique has proven to be a reliable and reproducible means of creating ICH in mice in a number of acute and chronic studies. We believe that our model will serve as an ideal paradigm for investigating the complex pathophysiology of hemorrhagic stroke. The protocol for establishing this model takes about 2 h.

Glutathione depletion activates mitogen-activated protein kinase (MAPK) pathways that display organ-specific responses and brain protection in mice

Because mitogen-activated protein kinases (MAPK) are downstream effectors of antioxidant responses, changes in GSH levels in an organism might induce organ-specific responses. To test our hypothesis, mice were treated intraperitoneally with L-buthionine-S-R-sulfoximine (BSO) to inhibit GSH synthesis. A time-related GSH depletion in the liver and kidney correlated with p38(MAPK) phosphorylation and induction of thioredoxin 1 (Tx-1) transcription. This positive regulation was associated with nuclear translocation of NF-kappaB and ATF-2 and c-Jun phosphorylation in the liver, but only c-Jun phosphorylation in the kidney. Increased levels of GSH were observed in the brain together with extracellular regulated kinase 2 (ERK2) activation, Nrf2 nuclear accumulation, and increases in transcription of Nrf2, xCT, gamma-glutamylcysteine synthetase (gammaGCSr), and Tx-1. Pretreatment with MAPK inhibitors SB203580 and U0126, or addition of the exogenous thiol N-acetylcysteine, abrogated both p38(MAPK) and ERK2 activation as well as downstream effects on gene expression. No effect on gammaGCSr was observed. These results indicate that in mice, GSH depletion is associated with p38(MAPK) phosphorylation in the liver and kidney and with ERK2 activation in the brain, in what could be considered part of the brain's protective response to thiol depletion.

Experimental intracerebral hematoma in the rat: Characterization by sequential magnetic resonance imaging, behavior, and histopathology. Effect of albumin therapy

We characterized acute intracerebral hemorrhage (ICH) in the rat by sequential magnetic resonance imaging (MRI) and correlated MRI findings with neurobehavior and histopathology. In addition, we investigated whether albumin treatment would reduce ICH-induced brain injury. ICH was produced in rats by a double-injection method in which 45 microl of fresh arterial blood was injected into the right striatum. Susceptibility-weighted (SWI) and T2-weighted (T2WI) MRI was carried out on a 4.7T magnet at 0-1 h, 6 h, 24 h, 72 h, and 7 days after ICH. Animals were treated with either 25% human albumin, 1.25 g/kg, or saline vehicle i.v. at 90 min after ICH. Neurological status was evaluated before ICH and after treatment (at 4 h, 24 h, 48 h, 72 h, and 7 days). Brains were then perfusion-fixed, re-imaged on an 11.7T magnet, and studied by histopathology and immunochemistry. MRI revealed a consistent hematoma involving the striatum and overlying corpus callosum, with significant volume changes over time. Lesion volumes computed from T2WI images and by histopathology agreed closely with one another and were highly correlated (p=0.002). SWI lesion volumes were also highly correlated to histological volumes (p<0.001) but overestimated histological hematoma volume by approximately 5-fold. Albumin treatment significantly improved neurological scores compared to saline at 72 h (3.8+/-0.6 vs. 1.5+/-0.7) and 7 days (3.8+/-0.4 vs. 1.3+/-0.5, respectively, p<0.05), but did not affect histological or MRI lesion volumes. Taken together, sequential MRI plus histopathology provides a comprehensive characterization of experimental ICH. Albumin treatment improves neurological deficit after ICH but does not affect MRI or histological hematoma size.

Inflammation after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating clinical event without effective therapies. Increasing evidence suggests that inflammatory mechanisms are involved in the progression of ICH-induced brain injury. Inflammation is mediated by cellular components, such as leukocytes and microglia, and molecular components, including prostaglandins, chemokines, cytokines, extracellular proteases, and reactive oxygen species. Better understanding of the role of the ICH-induced inflammatory response and its potential for modulation might have profound implications for patient treatment. In this review, a summary of the available literature on the inflammatory responses after ICH is presented along with discussion of some of the emerging opportunities for potential therapeutic strategies. In the near future, additional strategies that target inflammation could offer exciting new promise in the therapeutic approach to ICH.

Proteasomal inhibition in intracerebral hemorrhage: Neuroprotective and anti-inflammatory effects of bortezomib

Inflammation is an important pathophysiologic mechanism of injury induced by intracerebral hemorrhage (ICH). The ubiquitin-proteasome system (UPS) regulates the inflammatory responses via the up-regulation of several pro-inflammatory molecules. In this study, we determined that a potent proteasome inhibitor, bortezomib, exerted therapeutic effects in experimental model of ICH. Either bortezomib (0.05, 0.2, 0.5, 1mg/kg) or vehicle was intravenously administered 2h after ICH induction. The high doses of bortezomib caused high mortality rates. Bortezomib at 0.2 mg/kg reduced the early hematoma growth and alleviated hematoma volume and brain edema at 3 days after ICH, compared with the ICH-vehicle group. The numbers of myeloperoxidase(+) neutrophils, Ox42(+) microglia, and TUNEL(+) cells in the perihematomal regions were decreased by bortezomib. Bortezomib induced significant decrements of mRNA expression of TNF-alpha and IL-6. The production of iNOS and COX2 was also reduced significantly by bortezomib. We concluded that the early treatment with bortezomib induced a reduction in the early hematoma growth and mitigated the development of brain edema, coupled with a marked inhibitory effect on inflammation in ICH.

Suppression of Perfluoroisobutylene Induced Acute Lung Injury by Pretreatment with Pyrrolidine Dithiocarbamate

Perfluoroisobutylene (PFIB) is produced as a main by-product in large quantities by the fluoropolymer industry. As a highly toxic compound, even the case of brief inhalation of PFIB can result in acute lung injury (ALI), pulmonary edema and even death. To test for any preventive or therapeutic effects of pyrrolidine dithiocarbamate (PDTC), a NF-kappaB activation inhibitor, against PFIB inhalation-induced ALI, mice were exposed in a flow-past exposure system to PFIB and the prophylactic and therapeutic effects of PDTC were studied. The inhibitory effects of PDTC on ALI, the activation of NF-kappaB, as well as the expression of cytokines (IL-1beta and IL-8) after PFIB exposure were evaluated. The results demonstrated that pretreatment with PDTC (120 mg/kg, 30 min before PFIB exposure) could significantly lower the lung coefficient (wet lung-to-body weight ratio, dry lung-to-body weight ratio, water content in the lung, and lung wet-to-dry weight ratio) and protein content in bronchoalveolar lavage fluid (BALF), but no effects of PDTC were found when PDTC was treated after PFIB inhalation, suggesting a preventative effect rather than a therapeutic effect of PDTC. Furthermore, the above preventative effects of PDTC (when given at 30 min before PFIB exposure) on PFIB-induced lung injury were achieved in a dose-dependent manner. In support of these preventive effects of PDTC, our toxicological studies demonstrated that PFIB-inhalation induced a quick activation of NF-kappaB (0.5 h post PFIB exposure) and expression of IL-1beta and IL-8 (0.5 h and 1 h post PFIB exposure, respectively). Pretreatment with PDTC (120 mg/kg, 30 min before PFIB exposure) resulted in a significant inhibitive effect on the activation of NF-kappaB (0.5 h post PFIB exposure) and expression of IL-1beta and IL-8 (1 h post PFIB exposure). The mortality, the extent of lung injury of the mice indexed by lung coefficients, the content of total protein and albumin in BALF, as well as the lung histopathologic changes, were dramatically alleviated in PFIB exposure after pretreatment with PDTC, clearly suggesting that PDTC has a prophylactic role against PFIB inhalation-induced ALI, and that NF-kappaB activation might play a central role in initiating an acute inflammatory response and in causing injury to the lungs after PFIB inhalation.

Distinct patterns of intracerebral hemorrhage-induced alterations in NF-κB subunit, iNOS, and COX-2 expression

Transcription factor nuclear factor-kappaB (NF-kappaB), plays a key role in regulating inflammation in brain pathologies. The goal of this study was to characterize temporal changes in NF-kappaB activation, NF-kappaB subunit expression, and expression of selected NF-kappaB-regulated gene products [inducible form of nitric oxide synthase (iNOS) and cyclooxygenase-2], at the transcriptional and translational level in the brain after intracerebral hemorrhage (ICH). Employing the intrastriatal injection of autologous blood in rats to model ICH, we demonstrated, using NF-kappaB-DNA binding assay, a robust and prolonged NF-kappaB activation, starting as early as 15 min after the onset of ICH. Consequently, we demonstrated that the mRNA and protein for p50, p52, p65, c-Rel, and RelB NF-kappaB subunits, as well as IkappaBalpha were all up-regulated, with a time course ranging from minutes to days following ICH, depending on the subunit. Using reverse transcription-polymerase chain reaction to analyze mRNA and immunoblotting to analyze protein in ICH-affected tissue, we found robust induction of iNOS at both mRNA and protein levels that followed a time-course similar to changes in p65, p52, and RelB mRNA. Oddly, in contrast to iNOS, cyclooxygenase-2 mRNA and protein following an early transient increase demonstrated significant reduction in response to ICH. In summary, NF-kappaB activation occurs within minutes and persists for at least a week in response to ICH. This reaction utilizes different NF-kappaB regulatory subunits and is associated with the expression of selected target genes.

Neuronal expression of peroxisome proliferator-activated receptor-gamma (PPARγ) and 15d-prostaglandin J2—Mediated protection of brain after experimental cerebral ischemia in rat

Existing experimental evidence suggests that PPARgamma may play a beneficial role in neuroprotection from various brain pathologies. Here we found that focal cerebral ischemia induced by middle cerebral/common carotid arteries occlusion (MCA/CCAo) induced up-regulation of PPARgamma messenger RNA in the ischemic hemisphere as early as 6 h after the ischemic event. The increased PPARgamma mRNA expression was primarily associated with neurons in the ischemic penumbra, suggesting an important role for PPARgamma in neurons after ischemia. Intraventricular injection of 15d-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)), a proposed endogenous PPARgamma agonist, into the ischemic rat brains significantly increased the PPARgamma-DNA-binding activity and reduced infarction volume at 24 h after reperfusion. We propose that PPARgamma up-regulation in response to ischemia may contribute to PPARgamma activation in the presence of PPARgamma agonists. Activation of PPARgamma in neurons at an early stage after ischemia may represent a pro-survival mechanism against ischemic injury.

15d-Prostaglandin J2 activates peroxisome proliferator-activated receptor-gamma, promotes expression of catalase, and reduces inflammation, behavioral dysfunction, and neuronal loss after intracerebral hemorrhage in rats

Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a transcription factor that regulates the expression of various gene products that are essential in lipid and glucose metabolism, as well as that of the peroxisome-enriched antioxidant enzyme, catalase. Activation of PPARgamma is linked to anti-inflammatory activities and is beneficial for cardiovascular diseases. However, little is known about its role in intracerebral hemorrhage (ICH). 15-Deoxy-Delta(12,14)-prostaglandin J2 (15d-PGJ2) acts as a physiologic agonist for PPARgamma. In this study, we found that injection of 15d-PGJ2 into the locus of striatal hematoma increased PPARgamma-deoxyribonucleic acid (DNA) binding activity and the expression of catalase messenger ribonucleic acid (mRNA) and protein in the perihemorrhagic area. Additionally, 15d-PGJ2 significantly reduced nuclear factor-kappaB (NF-kappaB) activation and prevented neutrophil infiltration measured by myeloperoxidase (MPO) immunoassay, and also reduced cell apoptosis measured by terminal deoxynucleotide transferase dUTP nick-end labeling (TUNEL). In addition, 15d-PGJ2 reduced behavioral dysfunction produced by the ICH. Altogether, our findings indicate that injection of 15d-PGJ2 at the onset of ICH is associated with activation of PPARgamma and elevation of catalase expression, suppression of NF-kappaB activity, and restricted neutrophil infiltration. All these events predicted reduced behavioral deficit and neuronal damage.

Quantitative analysis of influence of sevoflurane on the reactivity of microglial cells in the course of the experimental model of intracerebral haemorrhage

BACKGROUND

Microglial cells play an important role in the pathophysiology of intracerebral haemorrhage. We have examined the possible influence of sevoflurane on the reactivity of microglial cells during intracranial haemorrhage.

METHODS

Forty adult male rats were divided into two groups. All animals were anaesthetized with fentanyl, dehydrobenzperidol and midazolam. In the experimental group animals additionally received sevoflurane 2.2 vol% end-tidal concentration. Intracranial haemorrhage was produced through infusion of blood into the striatum. The microglial cell population (numerical density of immunoreactive cells and their distribution) was assessed on days 1, 3, 7, 14 and 21 after producing a haematoma using antibodies OX42 and OX6.

RESULTS

In the control group significant differences in the density of OX42-ir cells between 3rd and 7th (81.86 vs. 129.99) (95% CI: -77.99 to -18.25, P = 0.0035) and between 14th and 21st (105.36 vs. 63.81) (95% CI: 13.21 to 69.89, P = 0.006) survival days were observed. However, significant increase of percentage of amoeboid OX42-ir cells between 3rd and 7th (0.98 vs. 48.71) (95% CI: -52.17 to -43.30, P = 0.0001) and between 7th and 14th (48.71 vs. 58.47) (95% CI: -13.96 to -5.55, P = 0.0002) and then their decrease - between 14th and 21st (58.47 vs. 31.74) (95% CI: 22.52 to 30.93, P = 0.0001) days of observation were noted. In the sevoflurane groups OX42-ir cells were not found. On the 3rd day the density of OX6-ir cells in the sevoflurane group was significantly lower than that in the control group (12.39 vs. 34.57) (95% CI: -49.78 to -2.96, P = 0.02). The percentage of an amoeboid form of OX6-ir cells was significantly lower in the sevoflurane group than that in the control group (27.31 vs. 82.03) (95% CI: -72.52 to -36.92, P = 0.0001) (58.76 vs. 82.37) (95% CI: -38.81 to -8.41, P = 0.003) (42.87 vs. 81.55) (95% CI: -53.23 to -24.10, P = 0.0001) respectively for 3rd, 7th and 14th days of survival.

CONCLUSION

Administration of sevoflurane during anaesthesia in animals with intracerebral haemorrhage evoked a decrease of activation of the microglial cells.

Nimodipine treatment to assess a modified mouse model of intracerebral hemorrhage

One of the main limitations of intracerebral hemorrhage (ICH) research is lack of reproducible animal models. ICH appears to be associated with a volume of edema and ischemic injury surrounding the hematoma that may be reduced by nimodipine due to its vasodilating and cytoprotective effects. The present study was designed to produce a modified ICH model in mice based on the double-injection method initially developed by Dr. Belayev and accordingly performed in 3 groups: to evaluate this model itself and to assess the pharmacological effects of nimodipine in this model, respectively. In 80 ICR mice (32 +/- 3 g), ICH was induced by 30 microL whole blood injection into the caudate nucleus. ICH animals were then randomly received either nimodipine (5 mg/kg) or vehicle intraperitoneal injection just before and every 24 h after ICH (total of four times). The changes for cortical blood flow (CBF) were studied by the technique of Laser Doppler Perfusion Measure (LDPM). Animals were rated on a behavioral test and sacrificed at 72 h after ICH. The brains were removed, and hematoma volume and brain edema were subsequently determined. Due to the vasodilating effect of nimodipine, ICH animals treated with nimodipine had marked improved CBF accompanied by the improvement of forelimb placing performance compared with vehicle-treated ICH animals, though there was no marked difference in the hematoma volume and brain water content. In conclusion, the 30 microL whole blood injection closely mimicked natural ischemic events that occurred in human massive ICH and confirmed the anti-ischemia effect of nimodipine. This study suggested that nimodipine could be markedly effective to reduce edema and hematoma volume when administered in combination with other neuroprotective agents because ICH can induce brain injury by multiple mechanisms.