Demonstration of increased endothelial-leukocyte adhesion molecule-1 mRNA expression in rat ischemic cortex

Poldip2 controls leukocyte infiltration into the ischemic brain by regulating focal adhesion kinase-mediated VCAM-1 induction

Stroke is a multiphasic process involving a direct ischemic brain injury which is then exacerbated by the influx of immune cells into the brain tissue. Activation of brain endothelial cells leads to the expression of adhesion molecules such vascular cell adhesion molecule 1 (VCAM-1) on endothelial cells, further increasing leukocyte recruitment. Polymerase δ-interacting protein 2 (Poldip2) promotes brain vascular inflammation and leukocyte recruitment via unknown mechanisms. This study aimed to define the role of Poldip2 in mediating vascular inflammation and leukocyte recruitment following cerebral ischemia. Cerebral ischemia was induced in Poldip2+/+ and Poldip2+/- mice and brains were isolated and processed for flow cytometry or RT-PCR. Cultured rat brain microvascular endothelial cells were used to investigate the effect of Poldip2 depletion on focal adhesion kinase (FAK)-mediated VCAM-1 induction. Poldip2 depletion in vivo attenuated the infiltration of myeloid cells, inflammatory monocytes/macrophages and decreased the induction of adhesion molecules. Focusing on VCAM-1, we demonstrated mechanistically that FAK activation was a critical intermediary in Poldip2-mediated VCAM-1 induction. In conclusion, Poldip2 is an important mediator of endothelial dysfunction and leukocyte recruitment. Thus, Poldip2 could be a therapeutic target to improve morbidity following ischemic stroke.

Microglial Lectins in Health and Neurological Diseases

Microglia are the innate sentinels of the central nervous system (CNS) and are responsible for the homeostasis and immune defense of the CNS. Under the influence of the local environment and cell-cell interaction, microglia exhibit a multidimensional and context-dependent phenotypes that can be cytotoxic and neuroprotective. Recent studies suggest that microglia express multitudinous types of lectins, including galectins, Siglecs, mannose-binding lectins (MBLs) and other glycan binding proteins. Because most studies that examine lectins focus on the peripheral system, the functions of lectins have not been critically investigated in the CNS. In addition, the types of brain cells that contribute to the altered levels of lectins present in diseases are often unclear. In this review, we will discuss how galectins, Siglecs, selectins and MBLs contribute to the dynamic functions of microglia. The interacting ligands of these lectins are complex glycoconjugates, which consist of glycoproteins and glycolipids that are expressed on microglia or surrounding cells. The current understanding of the heterogeneity and functions of glycans in the brain is limited. Galectins are a group of pleotropic proteins that recognize both β-galactoside-containing glycans and non- β-galactoside-containing proteins. The function and regulation of galectins have been implicated in immunomodulation, neuroinflammation, apoptosis, phagocytosis and oxidative bursts. Most Siglecs are expressed at a low level on the plasma membrane and bind to sialic acid residues for immunosurveillance and cell-cell communication. Siglecs are classified based on their inhibitory and activatory downstream signaling properties. Inhibitory Siglecs negatively regulate microglia activation upon recognizing the intact sialic acid patterns and vice versa. MBLs are expressed upon infection in cytoplasm and can be secreted in order to recognize molecules containing terminal mannose as an innate immune defense machinery. Most importantly, multiple studies have reported dysregulation of lectins in neurological disorders. Here, we reviewed recent studies on microglial lectins and their functions in CNS health and disease, and suggest that these lectin families are novel, potent therapeutic targets for neurological diseases.

Cinnamaldehyde inhibits inflammation and brain damage in a mouse model of permanent cerebral ischaemia

BACKGROUND AND PURPOSE

Recent findings suggest the importance of inflammation in the pathogenesis of cerebral ischaemia and its potential as a therapeutic target. Cinnamaldehyde is a diterpene with a wide range of anti-inflammatory effects thus may be advantageous in the treatment of cerebral ischaemia. The present study examined the potential therapeutic effects of cinnamaldehyde on cerebral ischaemia using a mouse model with permanent middle cerebral artery occlusion.

EXPERIMENTAL APPROACH

Male CD-1 mice, which had the middle cerebral artery occluded, were treated (i.p.) with cinnamaldehyde. Neuroprotection by cinnamaldehyde was analysed by evaluating neurological deficit scores, brain oedema and infarct volume. Expressions of signal transduction molecules and inflammatory mediators were measured by Western blotting, qRT-PCR and immunohistochemical staining. Activation of NF-κB was assessed by Western blotting, immunohistochemistry and immunofluorescence.

KEY RESULTS

Cinnamaldehyde reduced the neurological deficit scores, brain oedema and infarct volume. Cinnamaldehyde suppressed the activation of signal transduction molecules including toll-like receptor 4, tumour necrosis receptor-associated factor 6 and NF-κB, attenuated the increased levels of TNF-α, IL-1β, CCL2 and endothelial-leukocyte adhesion molecule-1 and ultimately reduced leukocyte infiltration into the ischaemic brain areas after cerebral ischaemia.

CONCLUSIONS AND IMPLICATIONS

Cinnamaldehyde protects against cerebral ischaemia injury by inhibiting inflammation, partly mediated by reducing the expression of toll-like receptor 4, tumour necrosis receptor-associated factor 6 and the nuclear translocation of NF-κB. Our findings suggest that cinnamaldehyde may serve as a new candidate for further development as a treatment for stroke.

(RS)-glucoraphanin purified from Tuscan black kale and bioactivated with myrosinase enzyme protects against cerebral ischemia/reperfusion injury in rats

Ischemic stroke is the result of a transient or permanent reduction in cerebral blood flow caused by the occlusion of a cerebral artery via an embolus or local thrombosis. Restoration of blood supply to ischemic tissues can cause additional damage known as reperfusion injury that can be more damaging than the initial ischemia. This study was aimed to examine the possible neuroprotective role of (RS)-glucoraphanin, bioactivated with myrosinase enzyme (bioactive RS-GRA), in an experimental rat model of brain ischemia/reperfusion injury (I/R). RS-GRA is a thiosaccharidic compound found in Brassicaceae, notably in Tuscan black kale (Brassica oleracea L. var. acephala sabellica). The mechanism underlying the inhibitory effects of bioactive RS-GRA on inflammatory and apoptotic responses, induced by carotid artery occlusion in rats, was carefully examined. Cerebral I/R was induced by the clamping of carotid artery for 1h, followed by 40 min of reperfusion through the release of clamp. Our results have clearly shown that administration of bioactive RS-GRA (10 mg/kg, i.p.) 15 min after ischemia, significantly reduces proinflammatory parameters, such as inducible nitric oxide synthase expression (iNOS), intercellular adhesion molecule 1 (ICAM-1), nuclear factor (NF)-kB traslocation as well as the triggering of the apoptotic pathway (TUNEL and Caspase 3 expression). Taken together our data have shown that bioactive RS-GRA possesses beneficial neuroprotective effects in counteracting the brain damage associated to I/R. Therefore, bioactive RS-GRA, could be a useful treatment in the cerebral ischemic stroke.

Solulin reduces infarct volume and regulates gene-expression in transient middle cerebral artery occlusion in rats

Background

Thrombolysis after acute ischemic stroke has only proven to be beneficial in a subset of patients. The soluble recombinant analogue of human thrombomodulin, Solulin, was studied in an in vivo rat model of acute ischemic stroke.

Methods

Male SD rats were subjected to 2 hrs of transient middle cerebral artery occlusion (tMCAO). Rats treated with Solulin intravenously shortly before reperfusion were compared to rats receiving normal saline i.v. with respect to infarct volumes, neurological deficits and mortality. Gene expression of IL-6, IL-1β, TNF-α, MMP-9, CD11B and GFAP were semiquantitatively analyzed by rtPCR of the penumbra.

Results

24 hrs after reperfusion, rats were neurologically tested, euthanized and infarct volumes determined. Solulin significantly reduced mean total (p = 0.001), cortical (p = 0.002), and basal ganglia (p = 0.036) infarct volumes. Hippocampal infarct volumes (p = 0.191) were not significantly affected. Solulin significantly downregulated the expression of IL-1β (79%; p < 0.001), TNF-α (59%; p = 0.001), IL-6 (47%; p = 0.04), and CD11B (49%; p = 0.001) in the infarcted cortex compared to controls.

Conclusions

Solulin reduced mean total, cortical and basal ganglia infarct volumes and regulated a subset of cytokines and proteases after tMCAO suggesting the potency of this compound for therapeutic interventions.

Plasma membrane calcium ATPase isoform 3 expression in single cells isolated from rat liver

The plasma membrane Ca(2+)-ATPase (PMCA) located in the hepatocyte is a controversial molecule in itself since it displays different features to those regarded as canonical for P-type Ca(2+)-ATPases, and from which transcript expression as well as catalytic activity continues to be under active investigation. Our aim in this study was to explore at a first glance, pmca isoform distribution using isolated parenchymal and non-parenchymal cells from rat liver tissue. Expression of pmca transcripts was analyzed in fresh or cell-enriched culture preparations, confirming pmca1 and pmca4 as the housekeeping isoforms in all cell types studied (hepatocytes, Kupffer cells, and stellate cells). However, for the first time we show expression of pmca3 transcripts edited at two different sites in both hepatocytes and non-parenchymal cells. Interestingly, employing non-parenchymal cells we demonstrate the specific expression of pmca3e transcripts previously considered nearly exclusive of excitable tissues. Real-time PCR quantification shows a significant decrease of pmca3 transcripts in cultured Kupffer and hepatic stellate cells in comparison with fresh cells. The presence of pmca2 along with pmca3 in all liver cell types studied suggests that high affinity isoforms are relevant to the adequate management of calcium in liver tissue, particularly when hepatic cells become activated by diverse stimuli.

Circulating intercellular adhesion molecule-1 and E-selectin in acute ischemic stroke

Exposure of endothelia to hypoxia followed by reperfusion, results in increased leukocyte activation and extravasation. These leukocytes potentiate ischemic neuronal damage. Extravasation of leukocytes is guided by adhesion molecule interactions on inflammatory and endothelial cells. Circulating adhesion molecules rapidly appear in peripheral blood. Commercially available ELISA kits were used to determine serum levels of E-selectin and intercellular adhesion molecule-1 (ICAM-1) in 36 patients at 1, 3, and 14 days after acute ischemic stroke. E-selectin levels were nonsignificantly increased at day 1, and decreased thereafter, reaching significantly lower values at day 14 in the stroke patients. ICAM-1 levels were similar in stroke patients at each sampling period, and did not differ from those of controls. Our data on ICAM-1 are in line with those of a recently published study. The decreasing circulating E-selectin may stem from endothelial cell damage, alterations in cytokine interactions, or unknown factors.

Cell adhesion molecules and ischemic stroke

OBJECTIVE

To describe the role of adhesion molecules in ischemic stroke.

METHODS

A PubMed search of literature pertaining to this study was conducted in April 2008 using specific keyword search terms pertaining to stroke and various listed subtopics related to adhesion molecules.

RESULTS

An important contribution of beta2-integrins (CD11/CD18), intercellular adhesion molecule and P-selectin in the recruitment of leukocytes as well as platelets in the post-ischemic cerebral microvasculature has been defined in related studies. Immunoblockade or genetic deletion of these adhesion molecules has been shown to reduce infarct volume, edema, behavioral deficits and/or mortality in different animal models of ischemic stroke. Anti-adhesion agents also appear to widen the therapeutic window for thrombolytic therapy in these experimental models. An emerging role of inflammatory signaling pathways has also been addressed in modulating adhesion properties of post-ischemic cerebral microvasculature. Despite the promising data obtained from animal studies, few clinical trials assessing anti-adhesion therapy in ischemic stroke have failed to show efficacy.

DISCUSSION

Several experiments using cell surface adhesion molecules as targets of stroke therapy are promising yet inadequate. Clinical trials using immune blockade of adhesion molecules by antibodies have failed due to immune reactions of the host. Further clinical trials are needed to test the efficacy of humanized antibodies or non-immunogenic agents that interfere with cell adhesion mechanisms. Adhesion blocking strategies seem to be effective particularly at reperfusion and use of these strategies with thrombolytic therapies justifies a continued effort to define the role of adhesion molecules in the pathophysiology of cerebral ischemia-reperfusion.

Investigational anti-inflammatory agents for the treatment of ischaemic brain injury

Stroke is the third leading cause of death and the leading cause of disability in Western countries. To date, only approximately 2% of stroke patients are eligible for thrombolysis treatment with recombinant tissue plasminogen activator. The very limited options available for stroke treatment and recent disappointing clinical trials in stroke call for novel therapeutic approaches. Inflammation represents one of the key pathophysiological mechanisms for the progression of ischaemic stroke. Recent advances in preclinical models of stroke using investigational small molecular antagonists, neutralising antibodies/proteins or genetically altered gene functions against various inflammatory mediators suggest a great therapeutic potential of anti-inflammation for ischaemic stroke. The scope of the present review is to update the evidence for a role of inflammatory pathways in stroke and to summarise the investigational drugs currently available both in preclinical and clinical development for potential treatment of ischaemic stroke.

Inflammation and stroke: putative role for cytokines, adhesion molecules and iNOS in brain response to ischemia

Ischemic stroke is a leading cause of death and disability in developed countries. Yet, in spite of substantial research and development efforts, no specific therapy for stroke is available. Several mechanism for neuroprotection have been explored including ion channels, excitatory amino acids and oxygen radicals yet none has culminated in an effective therapeutic effect. The review article on "inflammation and stroke" summarizes key data in support for the possibility that inflammatory cells and mediators are important contributing and confounding factors in ischemic brain injury. In particular, the role of cytokines, endothelial cells and leukocyte adhesion molecules, nitric oxide and cyclooxygenase (COX-2) products are discussed. Furthermore, the potential role for certain cytokines in modulation of brain vulnerability to ischemia is also reviewed. The data suggest that novel therapeutic strategies may evolve from detailed research on some specific inflammatory factors that act in spatial and temporal relationships with traditionally recognized neurotoxic factors. The dual nature of some mediators in reformatting of brain cells for resistance or sensitivity to injury demonstrate the delicate balance needed in interventions based on anti-inflammatory strategies.

Serum and cerebrospinal fluid concentrations of E-selectin in patients with aneurysmal subarachnoid hemorrhage

The goal of the present study was to determine concentrations of E-selectin in both cerebrospinal fluid (CSF) and serum of patients with aneurysmal subarachnoid hemorrhage (SAH) and to evaluate the correlation between the clinical parameters and E-selectin levels. Both CSF and serum samples obtained from 12 patients with aneurysmal SAH and 8 patients with hydrocephalus (control group) without any other known central nervous system disease were assayed for E-selectin by quantitative enzyme-linked immunosorbent assay and the results were compared between the two groups. Mean levels of soluble forms of E-selectin within the first 3 days and on the 5th and 7th days of SAH were 4.0 +/- 7.9, 2.8 +/- 5.2, and 3.1 +/- 4.9 ng/ml in the patient's CSF, and 33.7 +/- 9.2, 35.1 +/- 7.0, and 35.2 +/- 8.7 ng/ml in serum, respectively. In contrast, mean E-selectin levels were 0.1 +/- 0.2 ng/ml in CSF and 8.7 +/- 5.0 ng/ml in serum of control patients. The difference between groups was statistically significant regarding both CSF and serum E-selectin levels (P < 0.05). Thus, we have demonstrated a marked increase of E-selectin concentration in both CSF and serum of patients with aneurysmal SAH compared with control and suggest that blocking the interaction between E-selectin and vascular endothelium may have a beneficial effect on vasospasms.

Effect of P–selectin inhibition on leukocyteendothelium interaction and survival after global cerebral ischemia

Cerebral ischemia induces activation of leukocyte-endothelium interactions requiring upregulation of specific adhesion molecules including the selectins. The aim of the current study was to elucidate the therapeutic potency of P-selectin blockade on microcirculatory disturbances and secondary brain damage after global cerebral ischemia. Global cerebral ischemia for 15 minutes was induced in Mongolian gerbils. Functional blockade of P-selectin was achieved by pretreatment with the antibody RB 40.34 (2 mg/kg, n = 7). In vivo observation of brain microcirculation was performed by epifluorescence microscopy of a cranial window. Survival was assessed daily up to 4 days after ischemia. In the control group leukocyte rolling increased during reperfusion with a maximum at 3 h (28 +/- 14 x 100 microm(-1) x min(-1)) and was significantly reduced by the P-selectin antibody (13 +/- 9 x 100 microm(-1) x min(-1), p < 0.05). No effect on firm leukocyte adhesion was observed (4 +/- 3 vs. 2 +/- 1 x 100 microm(-1) x min(-1)). The survival of animals that received the Pselectin antibody (28 %) was significantly reduced compared with controls (71 %). Anti-P-selectin antibody reduces leukocyte rolling but has no positive effect on survival. Our data question the role of the inflammatory response in the development of secondary brain damage and do not support this kind of therapeutical approach in global cerebral ischemia.

Reduced brain edema and matrix metalloproteinase (MMP) expression by pre-reperfusion infusion into ischemic territory in rat

The aim in this study was to investigate whether our experimental model for stroke therapy, flushing the ischemic territory with saline prior to reperfusion, could ameliorate disruption of microvascular integrity by reducing matrix metalloproteinase (MMP) expression during reperfusion. Stroke in Sprague Dawley rats (n = 42) was induced by a 2-h right middle cerebral artery (MCA) occlusion using a novel intraluminal hollow filament. Prior to reperfusion, 24 of the ischemic rats received 6ml isotonic saline at 37 degrees C infused into the ischemic area through the filament. Brain edema was determined by comparing the percentage difference in brain volume between the right and left (contralateral to stroke site) hemispheres, while the expressions of MMP-2 and -9 mRNA were analyzed by real-time reverse transcriptase-polymerase chain reaction (real-time RT-PCR). A significant (p < 0.01) brain edema, determined by an increased brain volume of 19 +/- 4%, and overexpression of the mRNA encoding MMPs, determined by increased relative mRNA level ratio, were found in ischemic rats. The brain damage, in terms of brain edema (4 +/- 1%) and overexpression of MMPs, was significantly (p < 0.05) ameliorated as a result of saline flushing into the ischemic territory prior to reperfusion. This study has enhanced our understanding of the causal mechanisms by which the neuroprotective effect of ischemic area "flushing" can be achieved.

Increased diffusion of soluble adhesion molecules in meningitis, severe sepsis and systemic inflammatory response without neurological infection is associated with intrathecal shedding in cases of meningitis

OBJECTIVE

Sepsis and systemic inflammatory response syndrome (SIRS) result in the release in plasma of inflammatory cytokines and soluble forms of adhesion molecules in relation to endothelial activation. This study was designed to compare cerebrospinal fluid (CSF) concentrations of adhesion molecules in meningitis and SIRS without neurological infection and to evaluate in meningitis whether they originate from passive diffusion through damaged blood-CSF barrier or from local production.

DESIGN

Prospective observational study.

SETTING

University hospital medical intensive care unit.

PATIENTS

Nineteen patients with meningitis and 41 patients with sepsis or SIRS without cerebrospinal infection consecutively admitted to the critical care unit over an 18-month period.

INTERVENTIONS

Soluble forms of adhesion molecules (ICAM-1, VCAM-1, E-selectin) and cytokines (interleukin (IL)-1beta and TNF-alpha) were measured in paired CSF and blood samples.

RESULTS

Serum concentrations of soluble adhesion molecules and cytokines were increased in the two groups, without significant differences. The CSF concentrations were elevated in both cases, whereas patients with meningitis demonstrated significantly higher CSF concentrations of soluble ICAM-1, VCAM-1, E-selectin, and TNF-alpha ( p<0.001), with higher corresponding CSF/serum ratios. Correlations between CSF and serum concentrations were found only in meningitis. These correlations were strong for soluble ICAM-1 (r(2)=0.7, p<0.001) and E-selectin (r(2)=0.9, p<0.001), but weaker for VCAM-1. VCAM-1 CSF/serum ratios were increased, in comparison with ICAM-1 and E-selectin CSF/serum ratios, despite similar molecular weights. Serum and CSF levels of cytokines and adhesion molecules were not predictive of death for the whole population, except concentrations of ICAM-1 significantly increased in non-surviving patients ( p<0.05).

CONCLUSIONS

The CSF soluble adhesion molecules are increased in sepsis, SIRS and meningitis. In meningitis, the correlation between CSF and serum concentrations of adhesion molecules and the presence of a discrepancy of CSF/serum ratios for molecules of the same molecular weight may suggest intrathecal shedding in addition to diffusion through blood-CSF barrier.

Vascular endothelial growth factor (VEGF) in seizures: a double-edged sword

Vascular endothelial growth factor (VEGF) is a vascular growth factor which induces angiogenesis (the development of new blood vessels), vascular permeability, and inflammation. In brain, receptors for VEGF have been localized to vascular endothelium, neurons, and glia. VEGF is upregulated after hypoxic injury to the brain, which can occur during cerebral ischemia or high-altitude edema, and has been implicated in the blood-brain barrier breakdown associated with these conditions. Given its recently-described role as an inflammatory mediator, VEGF could also contribute to the inflammatory responses observed in cerebral ischemia. After seizures, blood-brain barrier breakdown and inflammation is also observed in brain, albeit on a lower scale than that observed after stroke. Recent evidence has suggested a role for inflammation in seizure disorders. We have described striking increases in VEGF protein in both neurons and glia after pilocarpine-induced status epilepticus in the brain. Increases in VEGF could contribute to the blood-brain barrier breakdown and inflammation observed after seizures. However, VEGF has also been shown to be neuroprotective across several experimental paradigms, and hence could potentially protect vulnerable cells from damage associated with seizures. Therefore, the role of VEGF after seizures could be either protective or destructive. Although only further research will determine the exact nature of VEGF's role after seizures, preliminary data indicate that VEGF plays a protective role after seizures.

Early NFkappaB activation is inhibited during focal cerebral ischemia in interleukin-1beta-converting enzyme deficient mice

Our previous study demonstrated that the inhibition of interleukin-1beta (IL-1beta) reduces ischemic brain injury; however, the molecular mechanism of the action of IL-1 in cerebral ischemia is unclear. We are investigating currently the role of NFkappaB during focal cerebral ischemia, using mutant mice deficient in the interleukin-1 converting enzyme gene (ICE KO) in a middle cerebral artery occlusion (MCAO) model. Adult male ICE KO and wild-type mice (n = 120) underwent up to 24 hr of permanent MCAO. Cytoplasmic phospho-NFkappaB/p65 expression in ischemic brain was examined using Western blot analysis and immunohistochemistry. NFkappaB DNA-binding activity was detected using electrophoretic mobility shift assay (EMSA). Furthermore, ICAM-1 expression was examined in both the ICE KO and wild-type mice (WT). Western blot analysis and immunostaining showed that the level of cytosolic phosphorylated NFkappaB/p65 increased after 2 and 4 hr of MCAO in WT mice; however, NFkappaB/p65 was significantly reduced after MCAO in the ICE KO mice (P < 0.05). EMSA showed that NFkappaB DNA-binding activity increased after MCAO in WT mice; but this effect was reduced in the ICE KO mice. The number of ICAM-1-positive vessels in the ischemic hemisphere was greatly attenuated in the ICE KO mice (P < 0.05), which paralleled the results of immunohistochemistry. Our results demonstrate that NFkappaB phosphorylation is reduced in ICE KO mice, suggesting that ICE or IL-1 are involved in early NFkappaB phosphorylation. Because cerebral ischemia induced infarction is significantly reduced in ICE KO mice, we conclude that early NFkappaB phosphorylation plays a disruptive role in the ischemic process.

Effect of the proteasome inhibitor MLN519 on the expression of inflammatory molecules following middle cerebral artery occlusion and reperfusion in the rat

Anti-inflammatory treatment with the proteasome inhibitor MLN519 has been previously reported to be neuroprotective against ischemic brain injury in rats. These effects have been related to inhibition of the transcription factor NF-kappaB, which is activated through ubiquitin-proteasomal degradation. The aim of this study was to evaluate the effects of MLN519 to alter the expression of several inflammatory genes under the control of NF-kappaB. Male Sprague-Dawley rats underwent middle cerebral artery occlusion (MCAo) followed by vehicle or MLN519 (1.0 g/kg, i.v.) treatment immediately after reperfusion of blood to the brain at 2h. Gene expression was evaluated 3-72 h post-MCAo. The most striking effects of intravenous treatment with MLN519 were associated with reductions in ICAM-1 expression at 3 h followed by reductions in E-selectin (12-72 h). Less dramatic reductions were observed in IL-1Beta (3-24 h) and TNF-Alpha (24 h) with no apparent effects on IL-6 and VCAM-1 mRNA levels. Immunohistochemical analysis revealed that the genes most dramatically affected by MLN519 had highest expression in endothelial cells and leukocytes (E-selectin, ICAM-1),indicating that these cell types may be the primary targets of intravenously delivered MLN519 treatment.

Quantitative real-time RT-PCR analysis of inflammatory gene expression associated with ischemia-reperfusion brain injury

Ischemia-reperfusion brain injury initiates an inflammatory response involving the expression of adhesion molecules and cytokines, some of which are regulated by the nuclear transcription factor NF-kappaB. In this study the authors examined mRNA expression levels for several important genes associated with inflammation at five time points (3, 6, 12, 24, and 72 hours) after transient middle cerebral artery occlusion (MCAO) in Sprague-Dawley rats. A sensitive and quantitative technique (TaqMan real-time QRT-PCR) was used to simultaneously measure mRNA levels for key cell adhesion molecules and inflammatory cytokines. Gene expression increased significantly in the injured hemisphere for interleukin (IL)-1beta (12-fold increase at 24 hours), IL-6 (25-fold increase at 6 hours) and ICAM-1 (4-fold increase at 24 hours), and the interhemispheric differences for these genes were significant for every time point examined (P < 0.05 for all values). Tumor necrosis factor-alpha mRNA was upregulated in the injured versus uninjured hemisphere from 3 to 24 hours (5-fold increase at 6 hours), while E-selectin showed a significant increase in mRNA levels from 6 to 24 hours after MCAO (10-fold increase at 6 hours) (P < 0.05 for all values). VCAM-1 mRNA levels did not respond differentially to injury at any time point between the two brain hemispheres. At all time points examined, activated NF-kappaB immunoreactivity was observed in cells throughout the infarct-damaged tissue. These results are consistent with the proinflammatory properties of the induced molecules, which are involved in the initiation of the inflammatory cascade, and may thus contribute to secondary cellular responses that lead to further brain damage.

Cytokine regulation of E-selectin in rat CNS microvascular endothelial cells: differential response of CNS and non-CNS vessels

We have compared the induced expression of E-selectin in primary cultures of rat brain microvascular endothelial cells (EC), pericytes and in non-CNS microvascular endothelium stimulated with the cytokines, IL-1beta (20 ng/ml), and tumor necrosis factor (TNF)-alpha (75 ng/ml). Expression was studied at both the protein and mRNA levels. Fluorescence in-situ hybridization (FISH) was used to examine de novo synthesis of E-selectin mRNA. Laser cytometric analysis was used as a novel approach to the quantitaion of FISH. In-situ hybridization was performed using two PCR-generated probes. The first probe (517 bp) spanned the lectin and epidermal growth factor (EGF)-like domain. The second probe (562 bp) spanned the CR3, 4, and 6 domains. E-selectin-specific mRNA was localized to the perinuclear regions of the EC. Both cytokines, IL-1beta and TNF-alpha significantly increased E-selectin gene expression in CNS EC but not pericytes. IL-1beta induced higher E-selectin mRNA levels than TNF-alpha. The maximum number of mRNA-positive cells was observed after stimulation for 4--6 h. Surface protein expression was sustained for up to 48 h following addition of cytokine. This was in contrast to the transient expression in non-CNS EC indicating that pure primary CNS EC display slightly different kinetics of E-selectin expression than non-CNS EC.

Endothelial markers and adhesion molecules in acute ischemic stroke--sequential change and differences in stroke subtype

The progress of a stroke concerns the activation of endothelial cells and platelets. We measured the plasma activities of von Willebrand factor (vWf) and the serum levels of soluble thrombomodulin (sTM) as endothelial markers, and the plasma concentrations of soluble P-selectin (sP-selectin) and soluble E-selectin (sE-selectin) as adhesion molecules during the acute (within 48 h from onset) and subacute (after 1 month from the onset) phases of 52 consecutive patients with acute ischemic stroke and 86 age-matched control subjects. The plasma vWf activities and levels of sP-and sE-selectins in stroke patients were significantly elevated compared with those in controls during both the acute and subacute phases. The serum levels of sTM in stroke patients were significantly higher than those in controls only during the subacute phase. In atherothrombotic infarction, the vWf activities and the levels of sP-selectin, markers for endothelial and platelet activation, remained higher until the subacute phase compared with controls, and the concentrations of sTM, a marker for endothelial injury, were increased during the subacute phase compared with during the acute phase. In lacunar infarction, the levels of sTM and sE-selectin of patients were higher only during the acute phase than controls. These findings suggest that the endothelial cell damage might be maintained until the subacute phase in atherothrombotic infarction, whereas it is remarkable only during the acute phase in lacunar infarction. The evaluation of endothelial markers and adhesion molecules would represent the pathophysiological states of stroke and may provide useful information for the treatment of the ischemic infarction.

Connexin43 null mutation increases infarct size after stroke

Glial-neuronal interactions have been implicated in both normal information processing and neuroprotection. One pathway of cellular interactions involves gap junctional intercellular communication (GJIC). In astrocytes, gap junctions are composed primarily of the channel protein connexin43 (Cx43) and provide a substrate for formation of a functional syncytium implicated in the spatial buffering capacity of astrocytes. To study the function of gap junctions in the brain, we used heterozygous Cx43 null mice, which exhibit reduced Cx43 expression. Western blot analysis showed a reduction in the level of Cx43 protein and GJIC in astrocytes cultured from heterozygote mice. The level of Cx43 is reduced in the adult heterozygote cerebrum to 40% of that present in the wild-type. To assess the effect of reduced Cx43 and GJIC on neuroprotection, we examined brain infarct volume in wild-type and heterozygote mice after focal ischemia. In our model of focal stroke, the middle cerebral artery was occluded at two points, above and below the rhinal fissure. Four days after surgery, mice were killed, the brains were sectioned and analyzed. Cx43 heterozygous null mice exhibited a significantly larger infarct volume compared with wild-type (14.4 +/- 1.4 mm(3) vs. 7.7 +/- 0.82 mm(3), P < 0.002). These results suggest that augmentation of GJIC in astrocytes may contribute to neuroprotection after ischemic injury.

Renoprotective effects of carvedilol in hypertensive-stroke prone rats may involve inhibition of TGF beta expression

1. The effect of carvedilol on renal function, structure and expression of TGF beta and the matrix proteins fibronectin, collagen I and collagen III, was evaluated in spontaneously hypertensive stroke-prone (SHR-SP) rats fed a high fat, high salt diet. 2. Carvedilol treatment for 11 to 18 weeks did not alter systolic blood pressure in SHR-SP rats, however, it resulted in a significant reduction in heart rate. 3. Carvedilol treatment reduced renal fibrosis and total, active and chronic renal damage to levels approaching those of WKY rats on a normal diet. 4. Urinary protein excretion was higher in SHR-SP rats (51+/-10 mg day(-1)) than WKY rats (18+/-2 mg day(-1)) and this was further increased when SHR-SP rats were fed a high fat, high salt diet (251+/-120 mg day(-1)). Treatment with carvedilol resulted in significantly lower urinary protein excretion (37+/-15 mg day(-1)). 5. The expression of TGF beta mRNA was significantly higher in SHR-SP rats compared to WKY rats and a further increase was observed when rats were fed a high fat, high salt diet. Renal TGF beta expression was significantly reduced by treatment with carvedilol. The expression of fibronectin and collagen I and collagen III mRNA showed a pattern similar to that observed with TGF beta mRNA expression. Collagen I mRNA expression followed a pattern similar to renal fibrosis. 6. These data indicate that carvedilol can provide significant renal protection in the absence of any antihypertensive activity and that the mechanisms involved in this action may include reduced expression of profibrotic factors such as TGF beta.

Serum concentration of adhesion molecules in patients with delayed ischaemic neurological deficit after aneurysmal subarachnoid haemorrhage: the immunoglobulin and selectin superfamilies

OBJECTIVES

Adhesion molecules are involved in the pathogenesis of cerebral ischaemia and may play a part in the pathophysiology of delayed ischaemic neurological deficit (DIND) after aneurysmal subarachnoid haemorrhage. It was hypothesised that after aneurysmal subarachnoid haemorrhage, adhesion molecules may play a part in the pathophysiology of DIND as reflected by significantly altered serum concentrations in patients with and without DIND.

METHODS

In a prospective study, mean serum concentrations of ICAM-1, VCAM-1, PECAM, and E, P, and L-selectin were compared between patients without (n=23) and with (n=13) DIND in patients with World Federation of Neurological Surgeons (WFNS) grades 1 or 2 subarachnoid haemorrhage. Serum was sampled from patients within 2 days of haemorrhage and on alternate days until discharge. Concentrations of adhesion molecules were measured by standard procedures using commercially available enzyme linked immunoabsorbent assays.

RESULTS

There were non-significant differences in serum concentrations of ICAM-1 (290.8 ng/ml v 238.4 ng/ml, p=0.0525), VCAM-1 (553.2 ng/ml v 425.8 ng/ml, p=0.053), and PECAM (22.0 ng/ml v 21.0 ng/ml, p=0.56) between patients without and with DIND respectively. The E-selectin concentration between the two patient groups (44.0 ng/ml v 37.4 ng/ml, p=0.33) was similar. The P-selectin concentration, however, was significantly higher in patients with DIND compared with those patients without DIND (149.5 ng/ml v 112.9 ng/ml, p=0.039). By contrast, serum L-selectin concentrations were significantly lower in patients with DIND (633.8 ng/ml v 897.9 ng/ml, p=0.013).

CONCLUSIONS

Of all the adhesion molecules examined in this study, P and L-selectin are involved in the pathophysiology of DIND after aneurysmal subarachnoid haemorrhage.

AT1 receptor antagonist prevents brain edema without lowering blood pressure

In order to investigate the role of Angiotensin II (AII) for the vasogenic cerebral edema, the AT1 receptor antagonist (TCV-116) was administered to 19-week-old stroke-prone spontaneously hypertensive rats (SHRSP) for 2 weeks at a dosage which did not decrease the blood pressure. Although no remarkable changes were found in blood pressure after treatment, the average brain weight of the treated group was relatively lower as compared to that of control SHRSP and no edematous changes were found in any brains. The immunohistochemical expression of intercellular adhesion molecule-1 (ICAM-1) was less and the glucose transporter-1 (GLUT-1) expression was much more intense in the endothelial cells of the micro vessels in the cerebral cortex of the treated group. Fibrinogen expression around micro-vessels was also remarkably reduced in the treated group. A decreased expression of ICAM-1 in the treated group was confirmed by RT-PCR analysis. These results indicate that the AT1 receptor blockade ameliorates hypertensive cerebral injury in a blood pressure-independent manner and suggest that AII may have an important role for endothelial injury in severe hypertension.

The selectin superfamily: the role of selectin adhesion molecules in delayed cerebral ischaemia after aneurysmal subarachnoid haemorrhage

Cerebral ischaemia and reperfusion injury may be exacerbated by leukocyte recruitment and activation. Adhesion molecules play a pivotal role in leukocyte recruitment. We report a prospective study of the potential role of the selectin family of adhesion molecules (E-, P- and L-selectin) in delayed cerebral ischaemia (DID) following aneurysmal subarachnoid haemorrhage. In patients with good grade SAH, we have compared serum concentrations of E-, P- and L-selectin, between patients who do, and do not develop delayed cerebral ischaemia. There was no difference in E-selectin concentration between the two groups (44.0 ng/ml vs. 37.4 ng/ml). Serum P-selectin concentration was significantly higher in patients with DID compared to those patients without DID (149.5 ng/ml vs. 112.9 ng/ml, p = 0.039). Serum L-selectin concentrations were significantly lower in patients with DID (633.8 ng/ml vs 897.9 ng/ml, p = 0.013). We conclude that P- and L-selectin are involved in the pathogenesis of DID following aneurysmal subarachnoid haemorrhage. The results of this study do not elucidate the exact role of each selectin in DID.

Gene expression in rats with renal disease treated with the angiotensin II receptor antagonist, eprosartan

The role of ANG II on renal and cardiac gene expression of matrix proteins was studied in rats with progressive renal disease. Induction of renal failure by five-sixths nephrectomy of Sprague-Dawley rats resulted in hypertension (163 +/- 19 vs. control pressures of 108 +/- 6 mmHg), proteinuria (83 +/- 47 vs. 14 +/- 2 mg/day), and increased renal expression of fibronectin, thrombospondin, collagen I and III, transforming growth factor-beta (TGF-beta), and plasminogen activator inhibitor-1 (PAI-1) mRNA. Treatment with the ANG II receptor antagonist, eprosartan (60 mg. kg(-1).day(-1)), lowered blood pressure (95 +/- 5 mmHg) and proteinuria (19 +/- 8 mg/d) and abrogated the increased TGF-beta, fibronectin, thrombospondin, collagens I and III, and PAI-1 mRNA expression. An increase in left ventricular weight was observed in five-sixths nephrectomized rats (0.13 +/- 0.01 vs. 0.08 +/- 0.01 g/100 g body wt), a response that was inhibited by eprosartan treatment (0.10 +/- 0.01 g/100 g). Left ventricular expression of TGF-beta and fibronectin was also increased in rats with renal disease; however, the small decreases in expression observed in eprosartan-treated rats did not reach statistical significance. These data suggest that eprosartan may be beneficial in progressive renal disease and that the mechanism of action includes inhibition of cytokine production in addition to antihypertensive activity.

Effects of the AT1 receptor antagonist on adhesion molecule expression in leukocytes and brain microvessels of stroke-prone spontaneously hypertensive rats

To elucidate the possible involvement of angiotensin II (AII) in the pathogenesis of microvascular changes in severe hypertension, we investigated the effects of angiotensin II type 1 (AT1) receptor antagonist and angiotensin-converting enzyme inhibitor (ACEI) on the expression of adhesion molecules of leukocytes and brain microvessels. Male stroke-prone spontaneously hypertensive rats (SHRSP) at 19 weeks of age were divided into three groups and age-matched Wistar-Kyoto rats (WKY) were used as the control group. AT1 receptor antagonist (TCV-116, 0.5 mg/kg/day) and ACEI (captopril, 20 mg/kg/day) were administered to SHRSP for 4 weeks. Mac-1 expression in leukocytes was investigated by flow cytometric analysis. For endothelial cells, we examined the expression of intercellular adhesion molecule-1 (ICAM-1), the AT1 receptor, and glucose transporter-1 (GLUT-1, a marker of the blood-brain barrier) using reverse transcription-polymerase chain reaction (RT-PCR). The blood pressure of AT1 receptor antagonist and ACEI-treated groups was slightly lower than that of the control, but was still greater than 220 mm Hg. Mac-1 expression, as well as ICAM-1 expression, was higher in control SHRSP than in WKY. Such enhanced expression of adhesion molecules in SHRSP was ameliorated by the administration of AT1 receptor antagonist or ACEI, the former being more effective. AT1 receptor expression was higher in control SHRSP than in WKY, and was lower in the AT1 receptor antagonist group, whereas no difference was found in the ACEI group. No significant differences were found in GLUT-1 expression among all groups. In the case of hypertensive cerebral injuries in SHRSP, leukocytes may have an important role for initiation via adhesion to endothelial cells. AT1 receptor antagonist showed a beneficial effect for the amelioration of enhanced expression of adhesion molecule in both leukocytes and endothelial cells. Thus, AII seems to be an important mediator for the hypertensive microvascular injuries.

Quantitative assessment of cell adhesion molecule gene expression in endomyocardial biopsy specimens from cardiac transplant recipients using competitive polymerase chain reaction

BACKGROUND

Adhesion of leukocytes to vascular endothelium is an early step in cardiac allograft rejection leading to migration of lymphocytes into parenchymal tissues. Cell adhesion molecule (CAM) protein expression appears to increase as a result of rejection. The relationship of CAM gene expression to rejection is less well defined. The goal of this study was to define cell adhesion molecule gene expression in relation to the presence of acute cellular rejection in endomyocardial biopsies from cardiac transplant recipients.

METHODS

To quantitatively assess intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and E-selectin gene expression, we developed a competitive PCR system using nonhomologous DNA fragments (MIMICs) with complementary sequences to CAM gene-specific primers as internal standards. MIMIC fragments with known concentrations were mixed in serial dilutions with constant amounts of cDNA from the biopsy specimens and amplified with common primers under the same polymerase chain reaction conditions. The relative CAM cDNA concentrations were determined by comparing the density of MIMIC to target cDNA bands on agarose gel. ICAM-1, VCAM-1, and E-selectin mRNA concentrations were analyzed from 38 cardiac transplant biopsies divided into 3 groups according to ISHLT rejection grade: group 1-grade 0 (n=13); group 2-grade 1A or 1B (n=13); group 3-grade 3A (n=12). Glyceraldehyde-3-phosphate dehydrogenase (a constitutive gene) was quantified in the same way as CAMs to normalize the relative levels of CAMs.

RESULTS

The results expressed as mean (1x10(-3) pM) (+/-SEM) in groups 1, 2, and 3, respectively, were: ICAM-1; 5+/-1; 57+/-4*; 64+/-13*, VCAM-1; 0.8+/-0.1; 6+/-1**; 9+/-1*, E-selectin; 0.4+/-0.2; 0.8+/-0.2; 0.4+/-0.1 (*P<0.001 versus group 1; **P<0.01 versus group 1).

CONCLUSIONS

ICAM-1 and VCAM-1 gene expression was increased during rejection in endomyocardial biopsy specimens. Competitive polymerase chain reaction can be used to quantitatively assess gene expression in biopsy specimens from patients.

Matrix remodeling after stroke. De novo expression of matrix proteins and integrin receptors

Following an ischemic insult to the central nervous system a reorganization of cells and tissue takes place as the surrounding cells attempt to limit the injury, repair the damage, and restore normal architecture of the brain. This tissue remodeling requires de novo synthesis of genes and proteins which enables cells to actively change their relationship with the existing extracellular matrix and with other cells to reorganize the damaged tissue. We have identified two key molecular components of the matrix remodeling process after focal ischemia: osteopontin (OPN) and its integrin receptor alpha v beta 3 (alpha v beta 3). OPN is initially expressed by activated macrophages and microglia in the periinfarct region (24-48 hr) and at later times (5-15 days) in the core infarct. After focal stroke the alpha v beta 3 was upregulated by astrocytes in the periinfarct region. Spatial and temporal analyses demonstrated that at 5 days after injury the alpha v beta 3-positive astrocytes were at a distance from the osteopontin-expressing macrophages; by 15 days the alpha v beta 3-expressing astrocytes were localized within an osteopontin-rich matrix. In vitro OPN was shown to induce migration of astrocytes in a Boyden chamber system. These data suggest that OPN derived from microglia at the infarct border zone (and possible macrophages in the infarct core) may serve as an "astrokine" (suggested term for astrocyte chemoattractant) to organize the astrocyte scar after focal stroke. Our data demonstrate profound changes in brain matrix remodeling after focal ischemic stroke, including the synthesis and release of matrix proteins alien to the normal brain, the expression of integrin receptors that ligate these proteins, and possibly a novel function for microglial-derived OPN in astrocyte migration after focal ischemia that may drive glial activation, organization, and repair functions.

Expression of receptors for complement anaphylatoxins C3a and C5a following permanent focal cerebral ischemia in the mouse

In the present study, we have examined the expression of anaphylatoxin C3a and C5a receptors (C3aR and C5aR) at the mRNA and protein levels in ischemic brain tissues following permanent middle cerebral artery (MCA) occlusion in the mouse. C3aR and C5aR mRNAs were both detected by semiquantitative reverse transcription and polymerase chain reaction (RT-PCR) and the cellular distribution of each receptor was analyzed by immunohistochemistry. Significant increases in the expression of C3aR and C5aR mRNAs in the ischemic cortex were observed; the expression of both reached a peak at 2 days after MCA occlusion (4.3- and 3.4-fold increases, respectively, compared with nonoperated control cortical samples; P < 0.00625 with Bonferroni's correction, n = 3). C3aR and C5aR stainings were found constitutively on neurons and astrocytes. In ischemic tissues, we observed that C3aR and C5aR were expressed de novo on endothelial cells of blood vessels, at 6 h and 2 days after MCA occlusion, respectively. C3aR and C5aR immunostaining was increased in macrophage-like cells and reactive astrocytes 7 days postocclusion. C3a and C5a may play an important role in promoting inflammatory and/or repair processes in the ischemic brain by regulating glial cell activation and chemotaxis.

Sgk, a putative serine/threonine kinase, is differentially expressed in the kidney of diabetic mice and humans

Differential display PCR was used to identify alternate expression of serum glucocorticoid-regulated kinase (Sgk) mRNA in diabetes-induced renal disease. Differential expression of Sgk mRNA was identified in the kidneys of normal and obese db/db mice, a model of select aspects of human diabetic nephropathy. Sgk mRNA was selectively increased in diabetic mouse kidneys. The Sgk mRNA levels remained constant in other tissues from obese db/db mice. An increase in Sgk mRNA was also observed in the human diabetic kidney. In addition, thrombin, which may play a role in the progression of renal disease, increased Sgk message in cell culture. Because the diabetes-induced increase in Sgk was only observed in the kidney, which is particularly susceptible to diabetes-induced damage, Sgk may play a role in diabetic nephropathy.

Molecular cloning and expression of the rat monocyte chemotactic protein-3 gene: a possible role in stroke

Using the suppression subtractive hybridization (SSH) strategy for differential gene cloning, we identified the induced expression of a rat homologue to murine and human monocyte chemotactic protein-3 (MCP-3) in ischemic brain. The 2.4-kilobase rat MCP-3 gene features high homology in gene structure and sequence to murine MCP-3. The temporal expression of MCP-3 mRNA was examined in brain tissue rendered ischemia by permanent or temporary occlusion of the middle cerebral artery (MCAO). A marked increase in MCP-3 mRNA was observed 12 h post-ischemia, with 49-fold and 17-fold increase (n=4, p<0.01) over control in the permanent or temporary MCAO, respectively. Significant induction of MCP-3 in the ischemic cortex was sustained up to 5 days after ischemic injury. The profile of MCP-3 mRNA induction paralleled leukocyte infiltration and accumulation that occur after focal stroke, suggesting a role for MCP-3 in recruiting these inflammatory cells into the ischemic tissue. Molecular cloning of rat MCP-3 should provide a valuable tool, as demonstrated in the present work, for the investigation of MCP-3 expression and function in rat disease models.

Inflammatory mediators and stroke: new opportunities for novel therapeutics

Contrary to previous dogmas, it is now well established that brain cells can produce cytokines and chemokines, and can express adhesion molecules that enable an in situ inflammatory reaction. The accumulation of neutrophils early after brain injury is believed to contribute to the degree of brain tissue loss. Support for this hypothesis has been drawn from many studies where neutrophil-depletion blockade of endothelial-leukocyte interactions has been achieved by various techniques. The inflammation reaction is an attractive pharmacologic opportunity, considering its rapid initiation and progression over many hours after stroke and its contribution to evolution of tissue injury. While the expression of inflammatory cytokines that may contribute to ischemic injury has been repeatedly demonstrated, cytokines may also provide "neuroprotection" in certain conditions by promoting growth, repair, and ultimately, enhanced functional recovery. Significant additional basic work is required to understand the dynamic, complex, and time-dependent destructive and protective processes associated with inflammation mediators produced after brain injury. The realization that brain ischemia and trauma elicit robust inflammation in the brain provides fertile ground for discovery of novel therapeutic agents for stroke and neurotrauma. Inhibition of the mitogen-activated protein kinase (MAPK) cascade via cytokine suppressive anti-inflammatory drugs, which block p38 MAPK and hence the production of interleukin-1 and tumor necrosis factor-alpha, are most promising new opportunities. However, spatial and temporal considerations need to be exercised to elucidate the best opportunities for selective inhibitors for specific inflammatory mediators.

Temporal modulation of cytokine expression following focal cerebral ischemia in mice

There is increasing evidence that the inflammatory response plays an important role in CNS ischemia. The murine model of focal ischemia, however, remains incompletely characterized. In this study we examined expression of several cytokines and the vascular adhesion molecule E-selectin, in order to characterize the molecular events following stroke in the C57BL/6J mouse. Using a multi-probe RNAse protection assay (RPA), mRNA for 19 cytokines was analyzed following permanent and transient occlusion of the middle cerebral artery in mice. In addition, samples from the same mice were analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR) to evaluate E-selectin mRNA expression levels. Several cytokine mRNAs showed a similar expression pattern in both permanent and transient CNS ischemia while others showed a temporal expression pattern that was dependent on the type of stroke. For both models, mRNA levels of TNFalpha rose early (4 h) followed by IL-6 (10-18 h) and a comparatively late increase (96 h) in TGFbeta1. IL-1alpha, IL-1beta and IL-1ra levels showed a model dependent shift in temporal expression. Reperfusion appeared to delay the induction of these cytokines. Temporal changes in cytokine mRNA expression in the mouse CNS occur following ischemic damage. Our findings demonstrate the utility and power of multi-probe RPA for evaluation of changes in cytokine mRNA levels. Moreover, this study is, to our knowledge the first to show temporal changes in cytokine mRNA in mouse cerebral ischemia, forming a basis for further exploration of the roles of these cytokines in modulating ischemic neuronal damage in this model.

The transcription factor interferon regulatory factor 1 is expressed after cerebral ischemia and contributes to ischemic brain injury

The transcription factor interferon regulatory factor 1 (IRF-1) is involved in the molecular mechanisms of inflammation and apoptosis, processes that contribute to ischemic brain injury. In this study, the induction of IRF-1 in response to cerebral ischemia and its role in ischemic brain injury were investigated. IRF-1 gene expression was markedly upregulated within 12 h of occlusion of the middle cerebral artery in C57BL/6 mice. The expression reached a peak 4 d after ischemia (6.0 +/- 1.8-fold; P < 0.001) and was restricted to the ischemic regions of the brain. The volume of ischemic injury was reduced by 23 +/- 3% in IRF-1(+/-) and by 46 +/- 9% in IRF-1(-/-) mice (P < 0.05). The reduction in infarct volume was paralleled by a substantial attenuation in neurological deficits. Thus, IRF-1 is the first nuclear transacting factor demonstrated to contribute directly to cerebral ischemic damage and may be a novel therapeutic target in ischemic stroke.

Mitogen-activated protein kinase cascade is involved in endothelin-1-induced rat puerperal uterine contraction

The regulation of mitogen-activated protein (MAP) kinase by endothelin-1 (ET-1) in cultured rat puerperal uterine myometrial cells was investigated. ET-1 caused the rapid stimulation of MAP kinase activity. ET-1-induced MAP kinase activation is neither extracellular Ca2+- nor intracellular Ca2+-dependent. ET-1 stimulation also led to an increase in phosphorylation of son-of-sevenless (SOS), and transfection of dominant negative SOS attenuated the ET-1-induced MAP kinase activity. Phorbol-12-myristate 13-acetate (PMA) also induced the MAP kinase activity, but pretreatment of the cultured cells with PMA, to down-regulate protein kinase C (PKC), did not abolish the activation of MAP kinase by ET-1. In addition, down-regulation of PKC had no effect on ET-1-induced SOS phosphorylation. Pertussis toxin, which inactivates Gi/Go proteins, blocked the ET-1-induced MAP kinase activation but not the PMA-induced MAP kinase activation. The results suggested that MAP kinase is acutely activated by ET-1 through a pertussis toxin-sensitive G protein and SOS, not through the PMA-sensitive PKC. In addition, although reverse-transcriptase PCR assays detected messenger RNA for both ET- 1 receptor subtypes in cultured rat puerperal uterine myometrial cells, ET-1-induced MAP kinase activity and uterine contraction were blocked by treatment with BQ485, an antagonist selective for an ET type A receptor (but not by BQ788, an ET type B receptor antagonist). Ritodrine, which is known to relax uterine muscle contraction, attenuated ET-1-induced MAP kinase activity. We further examined the role of MAP kinase pathway in uterine contraction using an inhibitor of MEK activity, PD098059. This inhibitor completely inhibited the ET-1-induced MAP kinase activation and partially, but significantly, inhibited the ET-1-induced uterine contraction. These results indicate that ET-1-induced MAP kinase signaling cascade may play an important role in the ET-1-induced uterine contraction.

The expression of P- and E-selectins in three models of middle cerebral artery occlusion

The expression and localization of P- and E-selectins in rat brain (n=126) were examined using immunohistochemical techniques at various time points after induction of middle cerebral artery (MCA) occlusion in the suture, thrombotic and embolic models of stroke. Expression of P- or E-selectin was not observed in brain tissue of sham operated control rats (n=9). P-selectin immunoreactivity was detected as early as 15 min and decreased to control level at 1 h after the onset of the MCA occlusion in all three models. P-selectin then slightly increased at 2 h and peaked at 6 h after MCA occlusion. E-selectin immunoreactivity was first observed at 2 h and peaked at 6 h and 12 h of after MCA occlusion in all three models. P- and E-selectin immunoreactivity was colocalized with von Willebrand factor immunoreactive microvessels. 90.4+/-2.0% of all vessels expressing P-selectin immunoreactivity were 7.5 to 30.0 micron in diameter; 3.6+/-1.4% were contained in vessels smaller than 7.5 micron, and 6.0+/-1.8% were localized in vessels greater than 30.0 micron in diameter. The percent distribution of E-selectin immunoreactive vessels were 75.9+/-2.1% in vessels 7.5 to 30.0 micron in diameter; 23.6+/-2.2% were in vessels smaller than 7.5 micron, and 0.6+/-0.4% were localized in vessels greater than 30.0 micron in diameter. These findings indicate that the temporal profiles of P- and E-selectin expression are independent of these models of MCA occlusion and are consistent with the time course of selectin mediated leukocyte infiltration after focal cerebral ischemia in the rat.

Cerebral vessels express interleukin 1beta after focal cerebral ischemia

Rapid and marked increased levels of expression of interleukin 1beta (IL-1beta) mRNA have been detected in animal models of cerebral ischemia. However, the protein production of IL-1beta and the cellular sources of IL-1beta are largely undefined after cerebral ischemia. In the present study, we have measured the cellular localization of IL-1beta protein in brain tissue from non-ischemic and ischemic mice using immunohistochemistry. Male C57B/6J (n=45) mice were subjected to middle cerebral artery (MCA) occlusion by a clot or a suture. The mice were sacrificed at time points spanning the period from 15 min to 24 h after onset of the MCA occlusion. Non-operated and sham-operated mice were used as control groups. A monoclonal anti-IL-1beta antibody was used to detect IL-1beta. In the non-operated and sham-operated mice, a few IL-1beta immunoreactive cells were detected scattered throughout both hemispheres. IL-1beta immunoreactive cells increased in the ischemic lesion as early as 15 min and peaked at 1 h to 2 h after MCA occlusion. IL-1beta immunoreactivity was detected in the cortex of the contralateral hemisphere 1 h after ischemia. By 24 h after onset of ischemia, IL-1beta immunoreactivity was mainly present adjacent to the ischemic lesion and in the non-ischemic cortex. IL-1beta immunoreactivity was found on endothelial cells and microglia. This study demonstrates an early bilateral expression of IL-1beta on endothelium after MCA occlusion in mice.

Inflammatory gene expression in cerebral ischemia and trauma. Potential new therapeutic targets

This review summarized evidence in support for the case that ischemia elicits an inflammatory condition in the injured brain. The inflammatory condition consists of cells (neutrophils at the onset and later monocytes) and mediators (cytokines, chemokines, others). It is clear that de novo upregulation of proinflammatory cytokines, chemokines and endothelial-leukocyte adhesion molecules in the brain follow soon after the ischemic insult and at a time when the cellular component is evolving. The significance of the inflammatory response to brain ischemia is not fully understood. Evidence is emerging in support of the possibility that the acute inflammatory reaction to brain ischemia may be causally related to brain damage. This evidence includes: 1) the capacity of cytokines to exacerbate brain damage; 2) the capacity of specific cytokine antagonists such as IL-1ra to reduce ischemic brain damage; 3) that depletion of circulating neutrophils reduces ischemic brain injury; 4) and that antagonists of the endothelial-leukocyte adhesion interactions (e.g., anti-ICAM-1) reduce ischemic brain injury. However, it should be kept in mind that cytokines were also argued to provide beneficial effects in brain injury as inferred from studies with TNF-receptor knock-out mice (p55 and p75 knock-out), which display increased sensitivity to brain ischemia, and the capacity of IL-1 to elicit the state of ischemic tolerance upon repeated administration. Nevertheless, the recent revelation on the capacity of ischemia to induce acute inflammation in the brain provides a new and fertile ground for new explorations for novel therapeutic agents that could confine the neuronal damage that follows ischemia. Furthermore, many of the genes that are upregulated by ischemia have growth-promotion capacity and therefore raise the possibility that such gene products may be useful in counteracting brain damage by enhancing repair and establishing compensatory mechanisms that enhance histological and functional recovery.

Microvascular responses to cerebral ischemia/inflammation

Experimental occlusion of a brain-supplying artery triggers tissue ischemia and subsequent inflammatory events that are initiated at the blood microvessel interface. Cytokine production and molecular adhesive events occur in the early moments following cerebral blood flow reduction, which underlie the transition from ischemic to inflammatory injury. Events both within the microvascular lumen and in the immediately surrounding tissue are involved. Cytokines, including TNF-alpha, IL-1 beta, IL-6, and PAF, are produced from the ischemic parenchyma and contribute to the endothelial cell expression of P-selectin, ICAM-1, and E-selectin. Platelet activation occurs paris passu and probably involves alpha-granule P-selectin to mediate PMN leukocyte-platelet interactions. Other integrin heterodimers are also involved in the early microvascular responses to ischemia. The response of the basal lamina and ECM is somewhat slower, entailing yet unproven mechanisms that most probably include the proteolytic processes of leukocyte transmigration. The modifications to microvascular structure are likely to affect both endothelial and astrocyte relationships, promote erythrocyte extravasation and hemorrhage, and contribute to tissue injury. Remodeling of the microvasculature, apparent in other tissues, involves a number of these processes. However, the enzymatic participants and regulating mechanisms are coming under study: the unraveling of regulatory mechanisms of adhesion receptor expression and their modulation, and the companion roles of integrins as mediators of structural integrity and intercellular signaling.

Postischemic expression of P-selectin immunoreactivity in rat brain

Change of immunoreactive P-selectin was examined in rat brain after transient middle cerebral artery (MCA) occlusion (O) with anti-P-selectin monoclonal antibody using brain samples of sham control and after ischemia. Temporal, spatial, and cellular changes of immunohistochemical expressions of P-selectin were evaluated with rat brain sections at 2 and 8 h, 1, 3, and 7 days of reperfusion after 1 h of MCAO. Western blot showed a single band at molecular weight of 140 kDa for P-selectin after ischemia. P-selectin immunoreactivity was not normally present in rat brain sections. However, it was expressed mainly in the post-capillary venules of the cerebral cortex and caudate in the MCA territory with a peak at 8 h-1 day. The expression was diminished by 3 days of reperfusion. The present results indicate that P-selectin was expressed from an earlier stage of reperfusion in post-capillary venules, and the expression became maximum at the same time both in the cerebral cortex and caudate.

Expressions of P-selectin- and HSP72-like immunoreactivities in rat brain after transient middle cerebral artery occlusion

The role of an adhesion molecule such as P-selectin may be important in the pathogenesis of stroke. However, temporal, spatial and cellular profiles of the expression of such a protein have not been fully studied. Change of immunoreactive P-selectin was examined in rat brain after transient middle cerebral artery (MCA) occlusion in comparison with that of 72 kDa heat shock protein (HSP72) which is a well known marker of cell injury. Western blot analyses were performed to ensure the selective detection of immunoreactive P-selectin and HSP72 proteins with each antibody using brain samples before and after ischemia. Temporal, spatial and cellular changes of immunohistochemical expressions of P-selectin and HSP72 were evaluated with rat brain sections at 2 and 8 h, and 1, 3 and 7 days of reperfusion after 1 h of MCA occlusion (MCAO). Hematoxylin-eosin (HE) staining was performed to evaluate brain cell damage at 3 and 7 days of reperfusion. Western blot showed a single band at molecular weights of 140 and 72 kDa for P-selectin and HSP72, respectively, only after ischemia. No significant band was observed without primary antibody. P-selectin-like immunoreactivity was not normally present in rat brain sections. However, it was expressed mainly in the post-capillary venules of the cerebral cortex and caudate in the MCA territory with a peak at 8 h to 1 day. The expression was diminished by 3 days of reperfusion. An immunoreactive HSP72 was scarcely present in the cerebral cortex and caudate of the sham control brain. However, the protein was induced in neurons of the MCA territory. The HSP72 induction was gradually intensified from 8 h with peaks at 1 day in the cortex and at 3 days in the caudate. The immunoreactivity decreased by 7 days. Histopathological study with HE staining showed no evident cell damage at 3 and 7 days of reperfusion. The present results indicate that temporal, spatial and cellular differences were present in the expressions of immunoreactive P-selectin and HSP72 proteins. P-selectin was expressed from an earlier stage of reperfusion in post-capillary venules, and the expression became maximum at the same time both in the cerebral cortex and caudate. In contrast, HSP72 induction began later in neurons and reached maximum at a different time between the cortex and caudate.

E-selectin in focal cerebral ischemia and reperfusion in the rat

The selectin family of glycoproteins facilitates the early phase of polymorphonuclear leukocyte adhesion to the endothelial cell and, thus, may promote ischemic cell damage. To evaluate E-selectin in the pathogenesis of focal cerebral ischemia and reperfusion injury, we cloned rat E-selectin cDNA and measured the temporal profiles E-selectin mRNA (Northern blot) and protein (immunohistochemistry) during (1 h of ischemia) and after (up to 1 week) transient (2 h) middle cerebral artery (MCA) occlusion in the male Wistar rat. We also tested the effect on these rats of administration of CY-1503, an analog of sialyl Lewis(x) (SLe(x)), on ischemia cell damage. mRNA for E-selectin was first detected in the ischemic hemisphere at 2 h of reperfusion and persisted to 46 h of reperfusion. E-selectin (protein) was localized to microvessels within the ischemic lesion at 0 h of reperfusion and persisted to 70 h of reperfusion. Treatment of the ischemic animals with CY-1503 (50 mg/kg) (n = 8) significantly reduced infarct volume by 42% (p < 0.05) and significantly reduced myeloperoxidase immunoreactive cells in the ischemic lesion by 60% (p < 0.05). These findings provide the first direct evidence for the involvement of E-selectin in transient MCA occlusion in rats and suggest that the E-selectin may facilitate neutrophil adhesion and subsequent cerebral ischemic cell damage.

Interferon-inducible protein-10 involves vascular smooth muscle cell migration, proliferation, and inflammatory response

Interferon-inducible protein-10 (IP-10) is a member of the C-X-C chemokine family. Using mRNA differential display, we isolated a rat homologue to murine and human IP-10 from lipopolysaccharide-stimulated carotid arteries. Our studies demonstrated that IP-10 is a potent mitogenic and chemotactic factor for vascular smooth muscle cells, the critical features of smooth muscle cells for their contribution to the pathogenesis of atherosclerosis and restenosis. IP-10 induced a concentration-dependent stimulation of DNA synthesis, cell proliferation, and cell migration of rat aortic smooth muscle cells. A concentration- and time-dependent IP-10 mRNA induction was observed in lipopolysaccharide- or interferon-gamma-stimulated, but not interleukin-1beta- or tumor necrosis factor-alpha-stimulated smooth muscle cells. A marked synergistic effect on IP-10 mRNA expression was observed when smooth muscle cells were challenged with interferon-gamma together with interleukin-1beta or tumor necrosis factor-alpha. Furthermore, IP-10 mRNA expression was induced in the rat carotid artery after balloon angioplasty. The mitogenic and chemotactic features of IP-10 for smooth muscle cells, along with its discrete induction in cultured vascular smooth muscle cells and in carotid arteries after balloon angioplasty (neointima formation) suggest that IP-10 may play an active and distinct role in vascular remodeling processes.

E-selectin expression on human brain microvascular endothelial cells

E-Selectin is an endothelial adhesion molecule involved in binding and targeting of neutrophils. Little is known of its expression in the brain. We examined the expression of E-selectin on cultured human brain microvascular endothelial cells (HBMEC). There was no basal expression of E-selectin on HBMEC but with I1-1b, tumor necrosis factor (TNF), or lipopolysaccharide (LPS) stimulation there was surface expression at 4 h. The expression was quantitatively less than on cultured human umbilical vein endothelial cells (HUVEC). The cytokine-induced upregulation was partially inhibited with the glutathione donor, N-acetylcysteine (NAC), the free radical scavenger, dimethylthiourea (DMTU; 15 mM) and dexamethasone (1 microM). Allopurinol (100 microM) had no effect. TNF activated nuclear factor kappa B (NF kappa B) in HBMEC. This activation could be attenuated by prior treatment with NAC and dexamethasone. Thiol donors and corticosteroids could play a role in inhibiting potentially deleterious neutrophil-endothelial interactions in inflammatory conditions involving the brain.