Effect of 3-aminobenzamide, PARP inhibitor, on matrix metalloproteinase-9 level in plasma and brain of ischemic stroke model

The involvement of Sting in exacerbating acute lung injury in sepsis via the PARP-1/NLRP3 signaling pathway

BACKGROUND

Interferon gene stimulator (Sting) is an indispensable adaptor protein that plays a crucial role in acute lung injury (ALI) induced by sepsis, and the PARP-1/NLRP3 signaling pathway may be an integral component of the inflammatory response mediated by Sting. However, the regulatory role of Sting in the PARP-1/NLRP3 pathway in ALI remains insufficiently elucidated.

METHODS

Using lipopolysaccharide (LPS) to induce ALI in C57BL/6 mice and HUVEC cells, an in vivo and in vitro model was established. In vivo, Sting agonists and inhibitors were administered, while in vitro, Sting was knocked down using siRNA. ELISA was employed to quantify the levels of IL-1β, IL-6, and TNF-α. TUNEL staining was conducted to assess cellular apoptosis, while co-immunoprecipitation was utilized to investigate the interaction between Sting and NLRP3. Expression levels of Sting, NLRP3, PARP-1, among others, were assessed via Western blotting and RT-qPCR. Lung HE staining and lung wet/dry ratio were evaluated in the in vivo mouse model. To validate the role of the PARP-1/NLRP3 signaling pathway, PARP-1 inhibitors were employed both in vivo and in vitro.

RESULTS

In vitro experiments revealed that the Sting agonist group exacerbated LPS-induced pulmonary pathological damage, pulmonary edema, inflammatory response (increased levels of IL-6, TNF-α, and IL-1β), and cellular injury, whereas the Sting inhibitor group significantly ameliorated the aforementioned injuries, with further improvement observed in the combination therapy of Sting inhibitor and PARP-1 inhibitor. Western blotting and RT-qPCR results demonstrated significant suppression of ICAM-1, VCAM-1, NLRP3, and PARP-1 expression in the Sting inhibitor group, with this reduction further enhanced in the Sting inhibitor + PARP-1 inhibitor treatment group, exhibiting opposite outcomes to the agonist. Furthermore, in vitro experiments using HUVEC cell lines validated these findings.

CONCLUSIONS

Our study provides new insights into the roles of Sting and the PARP-1/NLRP3 signaling pathway in inflammatory responses, offering novel targets for the development of therapeutic interventions against inflammatory reactions.

Vascular oxidative stress causes neutrophil arrest in brain capillaries, leading to decreased cerebral blood flow and contributing to memory impairment in a mouse model of Alzheimer’s disease

INTRODUCTION

In this study, we explore the role of oxidative stress produced by NOX2-containing NADPH oxidase as a molecular mechanism causing capillary stalling and cerebral blood flow deficits in the APP/PS1 mouse model of AD.

METHODS

We inhibited NOX2 in APP/PS1 mice by administering a 10 mg/kg dose of the peptide inhibitor gp91-ds-tat i.p., for two weeks. We used in vivo two-photon imaging to measure capillary stalling, penetrating arteriole flow, and vascular inflammation. We also characterized short-term memory function and gene expression changes in cerebral microvessels.

RESULTS

We found that after NOX2 inhibition capillary stalling, as well as parenchymal and vascular inflammation, were significantly reduced. In addition, we found a significant increase in penetrating arteriole flow, followed by an improvement in short-term memory, and downregulation of inflammatory gene expression pathways.

DISCUSSION

Oxidative stress is a major mechanism leading to microvascular dysfunction in AD, and represents an important therapeutic target.

Poly (ADP-ribose) polymerase: An Overview of Mechanistic Approaches and Therapeutic Opportunities in the Management of Stroke

Stroke is one of the leading causes of morbidity and mortality accompanied by blood supply loss to a particular brain area. Several mechanistic approaches such as inhibition of poly (ADP-ribose) polymerase, therapies against tissue thrombosis, and neutrophils lead to stroke's therapeutic intervention. Evidence obtained with the poly (ADP-ribose) polymerase (PARP) inhibition and animals having a deficiency of PARP enzymes; represented the role of PARP in cerebral stroke, ischemia/reperfusion, and neurotrauma. PARP is a nuclear enzyme superfamily with various isoforms, each with different structural domains and functions, and out of all, PARP-1 is the best-characterized member. It has been shown to perform multiple physiological as well as pathological processes, including its role in inflammation, oxidative stress, apoptosis, and mitochondrial dysfunction. The enzyme interacts with NF-κB, p53, and other transcriptional factors to regulate survival and cell death and modulates multiple downstream signaling pathways. Clinical trials have also been conducted using PARP inhibitors for numerous disorders and have shown positive results. However, additional information is yet to be established for the therapeutic intervention of PARP inhibitors in stroke. These agents' utilization appears to be challenging due to their unknown potential long-term side effects. PARP activity increased during ischemia, but its inhibition provided significant neuroprotection. Despite the increased interest in PARP as a pharmacological modulator for novel therapeutic therapies, the current review focused on stroke and poly ADP-ribosylation.

Radiation-induced neuroinflammation: a potential protective role for poly(ADP-ribose) polymerase inhibitors?

Radiotherapy (RT) plays a fundamental role in the treatment of glioblastoma (GBM). GBM are notoriously invasive and harbor a subpopulation of cells with stem-like features which exhibit upregulation of the DNA damage response (DDR) and are radioresistant. High radiation doses are therefore delivered to large brain volumes and are known to extend survival but also cause delayed toxicity with 50%-90% of patients developing neurocognitive dysfunction. Emerging evidence identifies neuroinflammation as a critical mediator of the adverse effects of RT on cognitive function. In addition to its well-established role in promoting repair of radiation-induced DNA damage, activation of poly(ADP-ribose) polymerase (PARP) can exacerbate neuroinflammation by promoting secretion of inflammatory mediators. Therefore, PARP represents an intriguing mechanistic link between radiation-induced activation of the DDR and subsequent neuroinflammation. PARP inhibitors (PARPi) have emerged as promising new agents for GBM when given in combination with RT, with multiple preclinical studies demonstrating radiosensitizing effects and at least 3 compounds being evaluated in clinical trials. We propose that concomitant use of PARPi could reduce radiation-induced neuroinflammation and reduce the severity of radiation-induced cognitive dysfunction while at the same time improving tumor control by enhancing radiosensitivity.

Modulation of Inflammasome and Pyroptosis by Olaparib, a PARP-1 Inhibitor, in the R6/2 Mouse Model of Huntington's Disease

Pyroptosis is a type of cell death that is caspase-1 (Casp-1) dependent, which leads to a rapid cell lysis, and it is linked to the inflammasome. We recently showed that pyroptotic cell death occurs in Huntington’s disease (HD). Moreover, we previously described the beneficial effects of a PARP-1 inhibitor in HD. In this study, we investigated the neuroprotective effect of Olaparib, an inhibitor of PARP-1, in the mouse model of Huntington’s disease. R6/2 mice were administered Olaparib or vehicle from pre-symptomatic to late stages. Behavioral studies were performed to investigate clinical effects of the compound. Immunohistochemical and Western blotting studies were performed to evaluate neuroprotection and the impact of the compound on the pathway of neuronal death in the HD mice. Our results indicate that Olaparib administration starting from the pre-symptomatic stage of the neurodegenerative disease increased survival, ameliorated the neurological deficits, and improved clinical outcomes in neurobehavioral tests mainly by modulating the inflammasome activation. These results suggest that Olaparib, a commercially available drug already in use as an anti-neoplastic compound, exerts a neuroprotective effect and could be a useful pharmaceutical agent for Huntington’s disease therapy.

HDAC Inhibitors Induce BDNF Expression and Promote Neurite Outgrowth in Human Neural Progenitor Cells-Derived Neurons

Besides its key role in neural development, brain-derived neurotrophic factor (BDNF) is important for long-term potentiation and neurogenesis, which makes it a critical factor in learning and memory. Due to the important role of BDNF in synaptic function and plasticity, an in-house epigenetic library was screened against human neural progenitor cells (HNPCs) and WS1 human skin fibroblast cells using Cell-to-Ct assay kit to identify the small compounds capable of modulating the BDNF expression. In addition to two well-known hydroxamic acid-based histone deacetylase inhibitors (hb-HDACis), SAHA and TSA, several structurally similar HDAC inhibitors including SB-939, PCI-24781 and JNJ-26481585 with even higher impact on BDNF expression, were discovered in this study. Furthermore, by using well-developed immunohistochemistry assays, the selected compounds were also proved to have neurogenic potential improving the neurite outgrowth in HNPCs-derived neurons. In conclusion, we proved the neurogenic potential of several hb-HDACis, alongside their ability to enhance BDNF expression, which by modulating the neurogenesis and/or compensating for neuronal loss, could be propitious for treatment of neurological disorders.

Therapeutic Targeting of Poly(ADP-Ribose) Polymerase-1 (PARP1) in Cancer: Current Developments, Therapeutic Strategies, and Future Opportunities

Poly(ADP-ribose) polymerase-1 (PARP-1) plays a central role in numerous cellular processes including DNA repair, replication, and transcription. PARP interacts directly, indirectly or via PARylation with various oncogenic proteins and regulates several transcription factors thereby modulating carcinogenesis. Therapeutic inhibition of PARP is therefore perceived as a promising anticancer strategy and a number of PARP inhibitors (PARPi) are currently under development and clinical evaluation. PARPi inhibit the DNA repair pathway and thus form the concept of synthetic lethality in cancer therapeutics. Preclinical and clinical studies have shown the potential of PARPi as chemopotentiator, radiosensitizer, or as adjuvant therapeutic agents. Recent studies have shown that PARP-1 could be either oncogenic or tumor suppressive in different cancers. PARP inhibitor resistance is also a growing concern in the clinical setting. Recently, changes in the levels of PARP-1 activity or expression in cancer patients have provided the basis for consideration of PARP-1 regulatory proteins as potential biomarkers. This review focuses on the current developments related to the role of PARP in cancer progression, therapeutic strategies targeting PARP-associated oncogenic signaling, and future opportunities in use of PARPi in anticancer therapeutics.

Synthesis of the novel PARP-1 inhibitor AG-690/11026014 and its protective effects on angiotensin II-induced mouse cardiac remodeling

We previously identified AG-690/11026014 (6014) as a novel poly(ADP-ribose) polymerase-1 (PARP-1) inhibitor that effectively prevented angiotensin II (Ang II)-induced cardiomyocyte hypertrophy. In the present study, we reported a new synthesis route for 6014, and investigated its protective effects on Ang II-induced cardiac remodeling and cardiac dysfunction and the underlying mechanisms in mice. We designed a new synthesis route to obtain a sufficient quantity of 6014 for this in vivo study. C57BL/6J mice were infused with Ang II and treated with 6014 (10, 30, 90 mg·kg^-1·d^-1, ig) for 4 weeks. Then two-dimensional echocardiography was performed to assess the cardiac function and structure. Histological changes of the hearts were examined with HE staining and Masson's trichrome staining. The protein expression was evaluated by Western blot, immunohistochemistry and immunofluorescence assays. The activities of sirtuin-1 (SIRT-1) and the content of NAD+ were detected with the corresponding test kits. Treatment with 6014 dose-dependently improved cardiac function, including LVEF, CO and SV and reversed the changes of cardiac structure in Ang II-infused mice: it significantly ameliorated Ang II-induced cardiac hypertrophy evidenced by attenuating the enlargement of cardiomyocytes, decreased HW/BW and LVW/BW, and decreased expression of hypertrophic markers ANF, BNP and β-MHC; it also prevented Ang II-induced cardiac fibrosis, as implied by the decrease in excess accumulation of extracellular matrix (ECM) components collagen I, collagen III and FN. Further studies revealed that treatment with 6014 did not affect the expression levels of PARP-1, but dose-dependently inhibited the activity of PARP-1 and subsequently restored the activity of SIRT-1 in heart tissues due to the decreased consumption of NAD+ and attenuated Poly-ADP-ribosylation (PARylation) of SIRT-1. In conclusion, the novel PARP-1 inhibitor 6014 effectively protects mice against AngII-induced cardiac remodeling and improves cardiac function. Thus, 6014 might be a potential therapeutic agent for heart diseases..

Poly(ADP-ribose)polymerase-1 hyperactivation in neurodegenerative diseases: The death knell tolls for neurons

Neurodegeneration is a salient feature of chronic refractory brain disorders like Alzheimer's, Parkinson's, Huntington's, amyotropic lateral sclerosis and acute conditions like cerebral ischemia/reperfusion etc. The pathological protein aggregates, mitochondrial mutations or ischemic insults typifying these disease conditions collude with and intensify existing oxidative stress and attendant mitochondrial dysfunction. Interlocking these mechanisms is poly(ADP-ribose) polymerase (PARP-1) hyperactivation that invokes a distinct form of neuronal cell death viz., 'parthanatos'. PARP-1, a typical 'moonlighting protein' by virtue of its ability to poly(ADP-ribosyl)ate a plethora of cellular proteins exerts diverse functions that impinge significantly on cellular processes. In addition, its interactions with various nuclear proteins like transcription factors and chromatin modifiers elicit varied transcriptional outcomes that wield pathological cellular responses. Further, emerging leitmotifs like mitochondrial and nucleolar PARPs and the novel aspects of gene expression regulation by PARP-1 and poly(ADP-ribosyl)ation can provide a holistic view of PARP-1's influence on cell vitality. In this review, we discuss the pathological underpinnings of PARP-1, with a special emphasis on mitochondrial dysfunction and cell death subroutines, in the realm of neurodegeneration. This would provide a deeper insight into the functions of PARP-1 in neurodegenerative conditions that would enable the development of more effective therapeutic strategies.

Nobiletin promotes antioxidant and anti-inflammatory responses and elicits protection against ischemic stroke in vivo

BACKGROUND

Post-ischemic oxidative stress and inflammation play pivotal roles in the pathogenesis of ischemic stroke and may represent therapeutic targets. Nobiletin (NOB) has been reported to elicit a variety of biological effects through its anti-oxidant and anti-inflammatory properties. Our previous study has demonstrated the beneficial effect of NOB in ischemic stroke, but the underlying mechanisms remain poorly defined. We therefore further investigated the role of NOB in cerebral ischemia and its potential mechanisms.

METHODS

Adult male Sprague-Dawley rats were randomly assigned to five groups: Sham (sham-operated+0.05% Tween-80), permanent middle cerebral artery occlusion (pMCAO+0.9% saline), Vehicle (pMCAO+0.05% Tween-80), NOB-L (pMCAO+NOB 10mg/kg) and NOB-H (pMCAO+NOB 25mg/kg) groups. Rats were pre-administered intraperitoneally once daily for 3 days prior to ischemia and then received once again immediately after surgery. Neurological deficit, brain edema and infarct volume were evaluated at 24h after stroke. Immunohistochemistry, western blot and RT-qPCR were used to detect the expression of Nrf2, HO-1, SOD1, NF-κB and MMP-9. SOD1, GSH and MDA were measured by spectrophotometer.

RESULTS

Compared with Vehicle group, neurological deficits and brain edema were relieved in NOB-H group, infarct volume was lessened in both NOB-L and NOB-H groups (P<0.05). NOB significantly increased the expression of Nrf2, HO-1, SOD1 and GSH, while decreased the levels of NF-κB, MMP-9 and MDA (P<0.05).

CONCLUSION

NOB may have a neuroprotective effect on cerebral ischemia, and this protection may be through upregulating Nrf2, HO-1 and downregulating NF-κB expression.

Oxidative DNA Damage Mediated by Intranuclear MMP Activity Is Associated with Neuronal Apoptosis in Ischemic Stroke

Evidence of the pathological roles of matrix metalloproteinases (MMPs) in various neurological disorders has made them attractive therapeutic targets. MMPs disrupt the blood-brain barrier and cause neuronal death and neuroinflammation in acute cerebral ischemia and are critical for angiogenesis during recovery. However, some challenges have to be overcome before MMPs can be further validated as drug targets in stroke injury. Identifying in vivo substrates of MMPs should greatly improve our understanding of the mechanisms of ischemic injury and is critical for providing more precise drug targets. Recent works have uncovered nontraditional roles for MMPs in the cytosol and nucleus. These have shed light on intracellular targets and biological actions of MMPs, adding additional layers of complexity for therapeutic MMP inhibition. In this review, we discussed the recent advances made in understanding nuclear location of MMPs, their regulation of intranuclear sorting, and their intranuclear proteolytic activity and substrates. In particular, we highlighted the roles of intranuclear MMPs in oxidative DNA damage, neuronal apoptosis, and neuroinflammation at an early stage of stroke insult. These novel data point to new putative MMP-mediated intranuclear actions in stroke-induced pathological processes and may lead to novel approaches to treatment of stroke and other neurological diseases.

Strategies for Pharmacological Organoprotection during Extracorporeal Circulation Targeting Ischemia-Reperfusion Injury

Surgical correction of congenital cardiac malformations or aortocoronary bypass surgery in many cases implies the use of cardiopulmonary-bypass (CPB). However, a possible negative impact of CPB on internal organs such as brain, kidney, lung and liver cannot be neglected. In general, CPB initiates a systemic inflammatory response (SIRS) which is presumably caused by contact of blood components with the surface of CPB tubing. Moreover, during CPB the heart typically undergoes a period of cold ischemia, and the other peripheral organs a global low flow hypoperfusion. As a result, a plethora of pro-inflammatory mediators and cytokines is released activating different biochemical pathways, which finally may result in the occurrence of microthrombosis, microemboli, in depletion of coagulation factors and haemorrhagic diathesis besides typical ischemia-reperfusion injuries. In our review we will focus on possible pharmacological interventions in patients to decrease negative effects of CPB and to improve post-operative outcome with regard to heart and other organs like brain, kidney, or lung.

PARP-1 Inhibition Is Neuroprotective in the R6/2 Mouse Model of Huntington's Disease

Poly (ADP-ribose) polymerase 1 (PARP-1) is a nuclear enzyme that is involved in physiological processes as DNA repair, genomic stability, and apoptosis. Moreover, published studies demonstrated that PARP-1 mediates necrotic cell death in response to excessive DNA damage under certain pathological conditions. In Huntington’s disease brains, PARP immunoreactivity was described in neurons and in glial cells, thereby suggesting the involvement of apoptosis in HD. In this study, we sought to determine if the PARP-1 inhibitor exerts a neuroprotective effect in R6/2 mutant mice, which recapitulates, in many aspects, human HD. Transgenic mice were treated with the PARP-1 inhibitor INO-1001 mg/Kg daily starting from 4 weeks of age. After transcardial perfusion, histological and immunohistochemical studies were performed. We found that INO 1001-treated R6/2 mice survived longer and displayed less severe signs of neurological dysfunction than the vehicle treated ones. Primary outcome measures such as striatal atrophy, morphology of striatal neurons, neuronal intranuclear inclusions and microglial reaction confirmed a neuroprotective effect of the compound. INO-1001 was effective in significantly increasing activated CREB and BDNF in the striatal spiny neurons, which might account for the beneficial effects observed in this model. Our findings show that PARP-1 inhibition could be considered as a valid therapeutic approach for HD.

3-aminobenzamide, a poly (ADP ribose) polymerase inhibitor, enhances wound healing in whole body gamma irradiated model

The custom use of radiotherapy was found to participate in the development of chronic unhealed wounds. In general, exposure to gamma radiation stimulates the production of reactive oxygen species (ROS) that eventually leads to damaging effect. Conversely, overexpression of a nuclear poly (ADP-ribose) polymerase enzyme (PARP) after oxidative insult extremely brings about cellular injury due to excessive consumption of NAD and ATP. Here, we dedicated our study to investigate the role of 3-aminobenzamide (3-AB), a PARP inhibitor, on pregamma irradiated wounds. Two full-thickness (6 mm diameter) wounds were created on the dorsum of Swiss albino mouse. The progression of wound contraction was monitored by capturing daily photo images. Exposure to gamma radiation (6Gy) exacerbated the normal healing of excisional wounds. Remarkably, topical application of 3-AB cream (50 µM) revealed a marked acceleration in the rate of wound contraction. Likewise, PARP inhibition ameliorated the unbalanced oxidative/nitrosative status of granulated skin tissues. Such effect was significantly revealed by the correction of the reduced antioxidant capacity and the enhanced lipid peroxidation, hydrogen peroxide, and myeloperoxidase contents. Moreover, application of 3-AB modified the cutaneous nitrite content throughout healing process. Conversely, the expressions of pro-inflammatory cytokines were down-regulated by PARP inhibition. The mitochondrial ATP content showed a lower consumption rate on 3-AB-treated wound bed as well. In parallel, the mRNA expressions of Sirt-1 and acyl-COA oxidase-2 (ACOX-2) were up-regulated; whom functions control the mitochondrial ATP synthesis and lipid metabolism. The current data suggested that inhibition of PARP-1 enzyme may accelerate the delayed wound healing in whole body gamma irradiated mice by early modifying the oxidative stress as well as the inflammatory response.

Neuroprotective Mechanisms of Taurine against Ischemic Stroke

Ischemic stroke exhibits a multiplicity of pathophysiological mechanisms. To address the diverse pathophysiological mechanisms observed in ischemic stroke investigators seek to find therapeutic strategies that are multifaceted in their action by either investigating multipotential compounds or by using a combination of compounds. Taurine, an endogenous amino acid, exhibits a plethora of physiological functions. It exhibits antioxidative properties, stabilizes membrane, functions as an osmoregulator, modulates ionic movements, reduces the level of pro-inflammators, regulates intracellular calcium concentration; all of which contributes to its neuroprotective effect. Data are accumulating that show the neuroprotective mechanisms of taurine against stroke pathophysiology. In this review, we describe the neuroprotective mechanisms employed by taurine against ischemic stroke and its use in clinical trial for ischemic stroke.

Adoptive regulatory T-cell therapy protects against cerebral ischemia

OBJECTIVE

Recent evidence suggests that functional deficiency in regulatory T cells (Tregs), an innate immunomodulator, exacerbates brain damage after cerebral ischemia. We therefore evaluated the effect of Treg transfer in rodent models of ischemic stroke and further investigated the mechanism underlying Treg-afforded neuroprotection.

METHODS

We examined the therapeutic potential of Tregs and the mechanisms of neuroprotection in vivo in 2 rodent models of ischemic stroke and in vitro in Treg-neutrophil cocultures using a combined approach including cell-specific depletion, gene knockout mice, and bone marrow chimeras.

RESULTS

Systemic administration of purified Tregs at 2, 6, or even 24 hours after middle cerebral artery occlusion resulted in a marked reduction of brain infarct and prolonged improvement of neurological functions lasting out to 4 weeks. Treg-afforded neuroprotection was accompanied by attenuated blood-brain barrier (BBB) disruption during early stages of ischemia, decreased cerebral inflammation, and reduced infiltration of peripheral inflammatory cells into the lesioned brain. Surprisingly, Tregs exerted early neuroprotection without penetrating into the brain parenchyma or inhibiting the activation of residential microglia. Rather, both in vivo and in vitro studies demonstrated that Tregs suppressed peripheral neutrophil-derived matrix metallopeptidase-9 production, thus preventing proteolytic damage of the BBB. In addition to its potent central neuroprotection, Treg treatment was shown to ameliorate poststroke lymphopenia, suggesting a beneficial effect on immune status.

INTERPRETATION

Our study suggests that Treg adoptive therapy is a novel and potent cell-based therapy targeting poststroke inflammatory dysregulation and neurovascular disruption.

Role of poly(ADP-ribose) polymerases in the regulation of inflammatory processes

PARP enzymes influence the immune system at several key points and thus modulate inflammatory diseases. PARP enzymes affect immune cell maturation and differentiation and regulate the expression of inflammatory mediators such as cytokines, chemokines, inducible nitric oxide synthase and adhesion molecules. Moreover, PARP enzymes are key regulators of cell death during inflammation-related oxidative and nitrosative stress. Here we provide an overview of the different inflammatory diseases regulated by PARP enzymes.

In vitro screening of NADPH oxidase inhibitors and in vivo effects of L-leucinethiol on experimental autoimmune encephalomyelitis-induced mice

Experimental autoimmune encephalomyelitis (EAE), a Th1 polarized demyelinating disease of the central nervous system, shares many pathological and clinical similarities with multiple sclerosis (MS). The objectives of this study were i) to evaluate the suppressive effects of L-leucinethiol (LeuSH), a metalloprotease inhibitor on EAE-induced mice and ii) to study the effects of LeuSH on matrix metalloproteinase-9 (MMP-9), NADPH oxidase and cytokines (IFN-γ, IL-5 and IL-10) in tissues and plasma of EAE mice as a measure of potential markers associated with EAE disease. C57BL/6 mice were immunized with myelin oligodendrocyte glycoprotein (MOG35-55) peptide in complete Freund's adjuvant to induce EAE. A significant difference was observed in body weights and clinical signs of LeuSH (8 mg/kg) administered EAE-induced mice compared to control mice. The findings of this study include alterations in the enzymatic expression of MMP-9, NADPH oxidase and cytokine levels in the brain, spinal cord, spleen, thymus and plasma of inhibitor-treated EAE mice as well as EAE-induced mice. The enzyme activities of NADPH oxidase were inhibited by LeuSH. From these results, it can be considered that LeuSH acts as one of the antigen candidates in ameliorating the clinical symptoms of EAE disease in mice.

Suppression of matrix metalloproteinase-9 expression in undifferentiated, non-apoptotic keratinocytes is abrogated by the cleavage of poly(ADP-ribose) polymerase-1

Matrix metalloproteinase (MMP)-9, an enzyme that degrades the extracellular matrix, has been implicated as a key enzyme in the process of tissue remodeling. This study demonstrates the regulation of MMP-9 transcription through a gene regulatory element in its promoter (the KRE-M9 element). The KRE-M9-binding protein was purified and identified as poly(ADP-ribose) polymerase-1 (PARP-1), which inhibits the transcription of MMP-9 similar to involucrin. This regulation occurs in non-apoptotic keratinocytes using the distinctive culture conditions of high and low Ca(2+) levels. PARP cleavage, which occurs during apoptosis, results in de-repression of MMP-9 promoter activity. These data clarify a new role of PARP-1 and suggest a physiologically relevant connection between caspase activation and MMP-9 expression.

A lipoxin A4 analog ameliorates blood-brain barrier dysfunction and reduces MMP-9 expression in a rat model of focal cerebral ischemia-reperfusion injury

LXA(4) methyl ester (LXA(4)ME), a lipoxin A(4) analog, reduces ischemic insult in the rat models of transient or permanent cerebral ischemic injury. We investigated whether LXA(4)ME could ameliorate blood-brain barrier (BBB) dysfunction after stroke by reducing matrix metalloproteinase (MMP)-9 expression. Adult male rats were subjected to 2-h middle cerebral artery occlusion (MCAO) followed by 24-h reperfusion. Brain infarctions were detected by triphenyltetrazolium chloride (TTC) staining. BBB dysfunction was determined by examining brain edema and Evans Blue extravasation. Temporal expression of MMP-9 was determined by zymography and Western blot. The presence of tissue inhibitors of metalloproteinase-1 (TIMP-1) was also determined by Western blot in tissue protein sample. Brain edema and Evans Blue leakage were significantly reduced after stroke in the LXA(4)ME group and were associated with reduced brain infarct volumes. MMP-9 activity and expression were inhibited by LXA(4)ME after stroke. In addition, LXA(4)ME significantly increased TIMP-1 protein levels. Our results indicate that LXA(4)ME reduces brain injury by improving BBB function in a rat model of MCAO, and that a relationship exists between BBB permeability and MMP-9 expression following ischemic insult. Furthermore, these results suggest that LXA(4)ME-mediated reduction of MMP-9 following stroke are attributed to increased TIMP-1 expression.

Microbleeds and free active MMP-9 are independent risk factors for neurological deterioration in acute lacunar stroke

BACKGROUND AND PURPOSE

in this prospective study, we evaluated mutual relationships amongst microbleeds, matrix metalloproteinase-9 (MMP-9) and neurological deterioration in patients with their first acute lacunar stroke.

METHODS

based on diffusion-weighted image findings, we recruited 206 patients with their first acute lacunar stroke. Those without a MRI scan were excluded. Small (a maximum lesion diameter of 15 mm) areas of subcortical gray and white matter with increased signals were considered as lacunar infarctions. GRE images were obtained within 24 h of the onset of stroke symptoms. Venous blood was sampled at base line (within 24 h). Clinical, biochemical, rheological and inflammatory parameters, neurological scales and free, active MMP-9 levels were compared between patients with and without microbleeds. Neurological deterioration was defined as an increase in more than two points on the National Institutes of Health Stroke Scale Score baseline 14 days after the onset of lacunar stroke.

RESULTS

of the patients, 79 (38.3%) had microbleeds and 48 (23.3%) showed neurological deterioration. Free, active MMP-9 and C-reactive protein (CRP) levels were significantly increased amongst patients with microbleeds (P < 0.001 and P = 0.047, respectively). Existence of microbleeds (RR = 2.47, 95% CI = 1.25-3.83) and increased free, active MMP-9 (RR = 1.10 per 10 ng/ml, 95% CI = 1.03-1.19) were identified as independent risk factors for neurological deterioration after adjusting for potential confounders.

DISCUSSION

ncreased levels of active MMP-9 and the existence of microbleeds might be useful in predicting the deterioration following an initial acute lacunar stroke.

Neuroprotective effects of a novel water-soluble poly(ADP-ribose) polymerase-1 inhibitor, MP-124, in in vitro and in vivo models of cerebral ischemia

Cerebral ischemia induces excessive activation of poly(ADP-ribose) polymerase-1 (PARP-1), leading to neuronal cell death and the development of post-ischemic dysfunction. Blockade of PARP-related signals during cerebral ischemia has become a focus of interest as a new therapeutic approach for acute stroke treatment. The purpose of the present study was to examine the pharmacological profiles of MP-124, a novel water-soluble PARP-1 inhibitor, and its neuroprotective effects on ischemic injury in vitro and in vivo. MP-124 demonstrated competitive inhibition of the PARP-1 activity of human recombinant PARP-1 enzyme (Ki=16.5nmol/L). In P388D(1) cells, MP-124 inhibited the LDH leakage induced by H(2)O(2) in a concentration-dependent manner. (IC(50)=20.8nmol/L). In rat primary cortical neurons, MP-124 also inhibited the NAD depletion and polymerized ADP-ribose formation induced by H(2)O(2) exposure. Moreover, we investigated the neuroprotective effects of MP-124 in rat permanent and transient stroke models. In the rat permanent middle cerebral artery occlusion (MCAO) model, MP-124 was administered intravenously for 24h from 5min after the onset of MCAO. MP-124 (1, 3 and 10mg/kg/h) significantly inhibited the cerebral infarction in a dose-dependent manner (18, 42 and 48%). In rat transient MCAO model, MP-124 was administered intravenously from 30min after the onset of MCAO. MP-124 (3 and 10mg/kg/h) significantly reduced the infarct volume (53% and 50%). The present findings suggest that MP-124 acts as a potent neuroprotective agent in focal ischemia and its actions can be attributed to a reduction in NAD depletion and PAR formation.

Anti-inflammatory mechanism of taurine against ischemic stroke is related to down-regulation of PARP and NF-κB

Taurine is reported to reduce tissue damage induced by inflammation and to protect the brain against experimental stroke. The objective of this study was to investigate whether taurine reduced ischemic brain damage through suppressing inflammation related to poly (ADP-ribose) polymerase (PARP) and nuclear factor-kappaB (NF-κB) in a rat model of stroke. Rats received 2 h ischemia by intraluminal filament and were then reperfused. Taurine (50 mg/kg) was administered intravenously 1 h after ischemia. Treatment with taurine markedly reduced neurological deficits, lessened brain swelling, attenuated cell death, and decreased the infarct volume 72 h after ischemia. Our data showed the up-regulation of PARP and NF-κB p65 in cytosolic fractions in the core and nuclear fractions in the penumbra and core, and the increases in the nuclear poly (ADP-ribose) levels and the decreases in the intracellular NAD+ levels in the penumbra and core at 22 h of reperfusion; these changes were reversed by taurine. Moreover, taurine significantly reduced the levels of tumor necrosis factor-α, interleukin-1β, inducible nitric oxide synthase, and intracellular adhesion molecule-1, lessened the activities of myeloperoxidase and attenuated the infiltration of neutrophils in the penumbra and core at 22 h of reperfusion. These data demonstrate that suppressing the inflammatory reaction related to PARP and NF-κB-driven expression of inflammatory mediators may be one mechanism of taurine against ischemic stroke.

Pyruvate-enriched cardioplegia suppresses cardiopulmonary bypass-induced myocardial inflammation

BACKGROUND

Cardiopulmonary bypass-induced oxidative stress initiates inflammation that can damage the myocardium. This study tested whether cardioplegia enriched with the intermediary metabolite and antioxidant pyruvate dampens postbypass myocardial inflammation.

METHODS

Pigs were maintained on cardiopulmonary bypass while their hearts were arrested for 60 minutes with 4:1 blood:crystalloid cardioplegia, in which the crystalloid contained 188 mM glucose ± 24 mM pyruvate. Pigs were weaned from bypass after 30 minutes of whole blood reperfusion and recovered for 4 hours. Glutathione (GSH) and glutathione disulfide (GSSG) were measured in coronary sinus plasma to indirectly monitor myocardial GSH redox state (GSH/GSSG). Left ventricular myocardium was sampled 4 hours after cardiopulmonary bypass for analyses of C-reactive protein, matrix metalloproteinases 2 and 9 and tissue inhibitor of metalloproteinase-2 (TIMP-2), and to assess neutrophil infiltration by histology and myeloperoxidase assay.

RESULTS

Coronary sinus GSH/GSSG fell 70% after cardiopulmonary bypass with control cardioplegia, but pyruvate cardioplegia produced a robust increase in coronary sinus GSH/GSSG that persisted for 4 hours after bypass. Myocardial C-reactive protein content increased 5.6-fold after control bypass, and neutrophil infiltration and myeloperoxidase activity also increased, but pyruvate-fortified cardioplegia prevented these inflammatory effects. Control cardioplegia lowered myocardial TIMP-2 content by 59% and increased matrix metalloproteinase-9 activity by 35% versus nonbypass sham values, but pyruvate cardioplegia increased TIMP-2 content ninefold versus control cardioplegia and prevented the increase in matrix metalloproteinase-9. Matrix metalloproteinase-2 was not affected by bypass ± pyruvate.

CONCLUSIONS

Pyruvate-enriched cardioplegia dampens cardiopulmonary bypass-induced myocardial inflammation. Increased GSH/GSSG and TIMP-2 may mediate pyruvate's effects.

Expression and activation of matrix metalloproteinase-9 and NADPH oxidase in tissues and plasma of experimental autoimmune encephalomyelitis in mice

Experimental autoimmune encephalomyelitis (EAE) is a widely used animal model for multiple sclerosis (MS) that can be induced by immunization with myelin antigens such as myelin oligodendrocyte glycoprotein (MOG). The objective of this study was (i) to investigate how matrix metalloproteinase-9 (MMP-9) and NADPH oxidase enzymes are affected in the EAE mouse model and (ii) to know whether peripheral organs also express these enzymes in the EAE model. MOG(33-55) was administered subcutaneously on two sites over the back. Pertussis toxin was administered intraperitoneally immediately after MOG and again two days later. A significant difference was observed in body weights and clinical signs of EAE-induced mice. MMP-9 and NADPH oxidase enzymes were measured in central nervous system (CNS) tissues, peripheral tissues and plasma of EAE-induced mice. The primary findings include the distribution pattern of MMP-9 in CNS and peripheral tissues, and alterations in the enzymatic expression of MMP-9 and NADPH oxidase in the CNS tissues, spleen and plasma of EAE-induced mice. From these results, it can be considered that the spleen as well as the CNS can act as target organs in EAE disease, and plasma MMP-9 and NADPH oxidase may contribute to the pathogenesis of the disease.

Poly(ADP-ribose)polymerase inhibitor can attenuate the neuronal death after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced neurotoxicity in mice

An excessive expression of poly(ADP-ribose)polymerase (PARP) has been demonstrated to play a key role in the pathogenesis of Parkinson's disease (PD). Here we investigated the therapeutic effect of the PARP inhibitor benzamide against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) neurotoxicity in mice. In our HPLC and Western blot analysis, pretreatment with benzamide showed a neuroprotective effect against MPTP neurotoxicity in mice. Posttreatment with benzamide also attenuated MPTP neurotoxicity in mice. Furthermore, our immunohistochemical study showed that posttreatment with benzamide significantly prevented neuronal damage by suppressing overexpression of neuronal, microglial, and astroglial PARP after MPTP treatment. These findings have important implications for the therapeutic time window and choice of PARP inhibitors in PD patients. Our present findings provide further evidence that PARP inhibitor may offer a novel therapeutic strategy for PD.

Calcium signal-initiated early activation of NF-kappaB in neurons is a neuroprotective event in response to kainic acid-induced excitotoxicity

We demonstrate that activation of nuclear factor kappaB (NF-kappaB) in neurons is neuroprotective in response to kainic acid (KA)-induced excitotoxicity. Combination of Western blotting, immunocytochemistry, and electrophoresis mobility shift assay showed that KA exposure induced a fast but transient nuclear translocation of the NF-kappaB p65 subunit and increased DNA-binding activity of NF-kappaB in primary cultured cortical neurons. The transient NF-kappaB activity was associated with upregulation of antiapoptotic Bcl-xL and XIAP gene products revealed by real-time PCR. Knockdown of p65 decreased neuronal viability and antiapoptotic gene expression. In addition, we showed that KA-stimulated DNA-binding activity of NF-kappaB was associated with reactive oxygen species and calcium signals, using AMPA/KA receptor antagonist, calcium chelator, and antioxidant. These results suggest that the fast and transient activation of NF-kappaB initiated by calcium signals is one of the important proximal events in response to KA-induced excitotoxicity, which has neuroprotective effect against KA-induced apoptosis.

Plasma and brain matrix metalloproteinase-9 after acute focal cerebral ischemia in rats

BACKGROUND AND PURPOSE

Plasma levels of matrix metalloproteinase-9 (MMP-9) have been proposed to be a useful biomarker for assessing pathological events in brain. Here, we examined the temporal profiles of MMP-9 in blood and brain using a rat model of acute focal cerebral ischemia.

METHODS

Plasma and brain levels of MMP-2 and MMP-9 were quantified at 3, 6, 12, and 24 hours after permanent middle cerebral artery occlusion in male Sprague-Dawley rats. Infarct volumes at 24 hours were confirmed with 2,3,5-triphenyl-tetrazolium-chloride staining.

RESULTS

In plasma, zymographic bands were detected between 70 and 95 kDa corresponding to pro-MMP-2, pro-MMP-9, and activated MMP-9. A higher 135-kDa band was also seen that is likely to be NGAL-conjugated MMP-9. After ischemia, there were no significant changes in pro-MMP-2, but plasma levels of pro-MMP-9 steadily increased over the course of 24 hours. Activated MMP-9 levels in plasma were significantly elevated only at 24 hours. Plasma NGAL-MMP-9 complexes showed a transient elevation between 3 to 6 hours, after which levels decreased back down to pre-ischemic baselines. In brain homogenates, pro-MMP-2, pro-MMP-9, and activated MMP-9 were seen but no NGAL-MMP-9 bands were detected. Compared to the contralateral hemisphere, MMP-2 and MMP-9 levels in ischemic brain progressively increased over the course of 24 hours. Overall levels of MMP-9 in plasma and brain were significantly correlated, especially at 24 hours. Plasma levels of pro-MMP-9 at 24 hours were correlated with final infarct volumes.

CONCLUSIONS

Elevated plasma levels of MMP-9 appear to be correlated with brain levels within 24 hours of acute cerebral ischemia in rats. Further investigation into clinical profiles of MMP-9 in acute stroke patients may be useful.

Erythropoietin increases the motility of human bone marrow-multipotent stromal cells (hBM-MSCs) and enhances the production of neurotrophic factors from hBM-MSCs

Cell therapy has been extensively studied as an approach to repair damage in nervous system diseases. Multipotent stromal cells [MSCs] are well known to have neuroprotective effects and neural differentiation potential. The ability to induce migration of MSCs near nervous system damage via direct transplantation or via intravenous injections and increase the secretion of neurotrophic factors from MSCs might improve our ability to repair damage to the nervous system through cell therapy. In the present study, we investigated whether recombinant human erythropoietin [rhEPO], known to have a hematopoietic effect, could increase the motility of human bone marrow [hBM]-MSCs and enhance production of neurotrophic factors from hBM-MSCs. Based on the results of our MTT assay, trypan blue staining, and bromodeoxyuridine ELISA, rhEPO treatment increases the viability of MSCs but not their proliferation. With a migration assay kit, we demonstrated that the motility of hBM-MSCs was enhanced in rhEPO-treated cells. Immunoblotting assays revealed increased expression of phospho-Akt, phospho-GSK-3beta, phospho-extracellular signal-regulated kinase (ERK), beta PAK-interacting exchange factor (PIX), CXCR4, phospho tyrosine kinase B (TrkB), and vascular endothelial growth factor receptor-2 [VEGFR-2] in rhEPO-treated cells. Reverse transcription-polymerase chain reaction and gelatin zymography demonstrated that rhEPO treatment induces MMP-2 mRNA level and activity. In the studies using ELISAs, we found that rhEPO could increase levels of stromal cell-derived factor-1alpha, VEGF, and brain-derived neurotrophic factors. These findings suggest that rhEPO can increase the viability and motility of hBM-MSCs by affecting various intracellular signals including Akt, ERK, beta-PIX, CXCR4, TrkB, VEGFR-2, and MMP-2 and can enhance the production of neurotrophic factors from hBM-MSCs.

Inhibition of GSK-3 reduces infarct volume and improves neurobehavioral functions

In the present study, we have investigated the effects of glycogen synthase kinase-3 (GSK-3) inhibition on infarct volume and neurobehavioral functions in a focal cerebral ischemia model. To achieve our goals, GSK-3 inhibitor II or VIII was injected at several time points and in varing dosages. GSK-3 inhibitor VIII was more effective than inhibitor II, and infarct volume and water content in the VIII group were significantly decreased 24h after the onset of ischemic stroke, as compared with the control group. These protective effects were associated with reductions of TUNEL-positive cells, neutrophil infiltration, glucose levels after ischemia, and GSK-3 enzyme activity. In addition, expressions of death and inflammation-related signals decreased and those of survival-related signals increased. Lastly, neurobehavioral functions were restored to a greater extent in the VIII group than in the control group. Together, these results suggest that GSK-3 inhibition reduces infarct volume and restores neurobehavioral functions.

Reduction of hemorrhagic transformation by PJ34, a poly(ADP-ribose)polymerase inhibitor, after permanent focal cerebral ischemia in mice

Hemorrhagic transformation is an aggravating event that occurs in 15 to 43% of patients suffering from ischemic stroke. This phenomenon due to blood-brain barrier breakdown appears to be mediated in part by matrix metalloproteinases (MMPs) among which MMP-2 and MMP-9 could be particularly involved. Recent experimental studies demonstrated that post-ischemic MMP-9 overexpression is regulated by poly(ADP-ribose)polymerase (PARP). In this context, our study aimed to evaluate the effect of PJ34 (N-(6-oxo-5,6-dihydrophenanthridin-2-yl)-2-(N,N-dimethylamino)acetamide), a potent PARP inhibitor, on MMP-2 and MMP-9 levels and on hemorrhagic transformations in a model of permanent focal cerebral ischemia in mice. PJ34 (6.25-12.5 mg/kg, i.p.) was given at the time of ischemia onset and 4 h later. Hemorrhagic transformations, divided into microscopic and macroscopic hemorrhages, were counted 48 h after ischemia on 12 coronal brain slices. Microscopic and macroscopic hemorrhages were respectively reduced by 38% and 69% with 6.25 mg/kg PJ34. The anti-hemorrhagic effect of PJ34 was associated with a 57% decrease in MMP-9 overexpression assessed by gelatin zymography. No increase in MMP-2 activity was observed after ischemia in our model. The vascular protection achieved by PJ34 was associated with a reduction in the motor deficit (P<0.05) and in infarct volume (-31%, P<0.01). In conclusion, our study demonstrates for the first time that PJ34 reduces hemorrhagic transformations after cerebral ischemia. Thus this PARP inhibitor exhibits both anti-hemorrhagic and neuroprotective effects that may be of valuable interest for the treatment of stroke.

Molecular mechanisms of apoptosis in cerebral ischemia: multiple neuroprotective opportunities

Cerebral ischemia/reperfusion (I/R) injury triggers multiple and distinct but overlapping cell signaling pathways, which may lead to cell survival or cell damage. There is overwhelming evidence to suggest that besides necrosis, apoptosis do contributes significantly to the cell death subsequent to I/R injury. Both extrinsic and intrinsic apoptotic pathways play a vital role, and upon initiation, these pathways recruit downstream apoptotic molecules to execute cell death. Caspases and Bcl-2 family members appear to be crucial in regulating multiple apoptotic cell death pathways initiated during I/R. Similarly, inhibitor of apoptosis family of proteins (IAPs), mitogen-activated protein kinases, and newly identified apoptogenic molecules, like second mitochondrial-activated factor/direct IAP-binding protein with low pI (Smac/Diablo), omi/high-temperature requirement serine protease A2 (Omi/HtrA2), X-linked mammalian inhibitor of apoptosis protein-associated factor 1, and apoptosis-inducing factor, have emerged as potent regulators of cellular apoptotic/antiapoptotic machinery. All instances of cell survival/death mechanisms triggered during I/R are multifaceted and interlinked, which ultimately decide the fate of brain cells. Moreover, apoptotic cross-talk between major subcellular organelles suggests that therapeutic strategies should be optimally directed at multiple targets/mechanisms for better therapeutic outcome. Based on the current knowledge, this review briefly focuses I/R injury-induced multiple mechanisms of apoptosis, involving key apoptotic regulators and their emerging roles in orchestrating cell death programme. In addition, we have also highlighted the role of autophagy in modulating cell survival/death during cerebral ischemia. Furthermore, an attempt has been made to provide an encouraging outlook on emerging therapeutic approaches for cerebral ischemia.

Poly(ADP-ribose) polymerase inhibitor is neuroprotective in epileptic rat via apoptosis-inducing factor and Akt signaling

3-Aminobenzamide (3-AB), an inhibitor of poly(ADP-ribose) polymerase (PARP), has been proved to have neuroprotective properties. In this study, we examined the role of 3-AB in rat hippocampal neuron death induced by seizures. Our data showed that the seizures resulted in PARP activation and translocation of the apoptosis-inducing factor from the mitochondria to the nucleus, leading to neuron death. These effects could, however, all be abolished by 3-AB. Moreover, we showed that 3-AB facilitated Akt activation and decreased the activity of its downstream target, glycogen synthase kinase-3beta. Altogether, our data suggested that 3-AB might have a therapeutic value in seizure-induced hippocampal neuron damage, probably due to the inhibition of apoptosis and activation of Akt cell survival signaling.

Pyruvate enhances neurological recovery following cardiopulmonary arrest and resuscitation

PURPOSE

Cerebral oxidative stress and metabolic dysfunction impede neurological recovery from cardiac arrest-resuscitation. Pyruvate, a potent antioxidant and energy-yielding fuel, has been shown to protect against oxidant- and ischemia-induced neuronal damage. This study tested whether acute pyruvate treatment during cardiopulmonary resuscitation can prevent neurological dysfunction and cerebral injury following cardiac arrest.

METHODS

Anesthetized, open-chest mongrel dogs underwent 5 min cardiac arrest, 5 min open-chest cardiac compression (OCCC), defibrillation and 3-day recovery. Pyruvate (n=9) or NaCl volume control (n=8) were given (0.125 mmol kg(-1) min(-1) i.v.) throughout OCCC and the first 55 min recovery. Sham dogs (n=6) underwent surgery and recovery without cardiac arrest-resuscitation.

RESULTS

Neurological deficit score (NDS), evaluated at 2-day recovery, was sharply increased in NaCl-treated dogs (10.3+/-3.5) versus shams (1.2+/-0.4), but pyruvate treatment mitigated neurological deficit (NDS=3.3+/-1.2; P<0.05 versus NaCl). Brain samples were taken for histological examination and evaluation of inflammation and cell death at 3-day recovery. Loss of pyramidal neurons in the hippocampal CA1 subregion was greater in the NaCl controls than in pyruvate-treated dogs (11.7+/-2.3% versus 4.3+/-1.2%; P<0.05). Cardiac arrest increased caspase-3 activity, matrix metalloproteinase activity, and DNA fragmentation in the CA1 subregion; pyruvate prevented caspase-3 activation and DNA fragmentation, and suppressed matrix metalloproteinase activity.

CONCLUSION

Intravenous pyruvate therapy during cardiopulmonary resuscitation prevents initial oxidative stress and neuronal injury and enhances neurological recovery from cardiac arrest.

Neuroprotective effects of NU1025, a PARP inhibitor in cerebral ischemia are mediated through reduction in NAD depletion and DNA fragmentation

Oxidative stress induced cell injury is reported to contribute to the pathogenesis of cerebral ischemia. Reactive oxygen species such as hydrogen peroxide (H2O2) and superoxide radical along with nitric oxide and peroxynitrite generated during ischemia-reperfusion injury, causes the overactivation of poly (ADP-ribose) polymerase (PARP) leading to neuronal cell death. In the present study we have evaluated the effects of PARP inhibitor, 8-hydroxy-2 methyl-quinazolin-4-[3H]one (NU1025) in H2O2 and 3-morphilinosyndonimine (SIN-1) induced cytotoxicity in PC12 cells as well as in middle cerebral artery occlusion (MCAO) induced focal cerebral ischemia in rats. Exposure of PC12 cells to H2O2 (0.4 mM) and SIN-1 (0.8 mM) resulted in a significant decrease in cell viability after 6 h. Pretreatment with NU1025 (0.2 mM) restored cell viability to approximately 73 and 82% in H2O2 and SIN-1 injured cells, respectively. In MCAO studies, NU1025 was administered at different time points (1 h before reperfusion, immediately before reperfusion, 3 h after reperfusion and 6 h after reperfusion). NU1025 at 1 and 3 mg/kg reduced total infarct volume to 25% and 45%, respectively, when administered 1 h before reperfusion. NU1025 also produced significant improvement in neurological deficits. Neuroprotection with NU1025 was associated with reduction in PAR accumulation, reversal of brain NAD depletion and reduction in DNA fragmentation. Results of this study demonstrate the neuroprotective activity of NU1025 and suggest its potential in cerebral ischemia.

Anti-inflammatory effects of PJ34, a poly(ADP-ribose) polymerase inhibitor, in transient focal cerebral ischemia in mice

BACKGROUND AND PURPOSE

Activation of poly(ADP-ribose) polymerase (PARP) is deleterious during cerebral ischemia. We assessed the influence of PARP activation induced by cerebral ischemia on the synthesis of proinflammatory mediators including the cytokines, tumour necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) and the adhesion molecules, E-selectin and intercellular adhesion molecule-1 (ICAM-1).

EXPERIMENTAL APPROACH

Ischemia was induced by intravascular occlusion of the left middle cerebral artery for 1 h in male Swiss mice anaesthetized with ketamine and xylazine. The PARP inhibitor PJ34 (1.25-25 mg kg(-1)) was administered intraperitoneally 15 min before and 4 hours after, the onset of ischemia. Animals were killed 6 h or 24 h after ischemia and cerebral tissue removed for analysis.

KEY RESULTS

Ischemia increased TNF-alpha protein in cerebral tissue at 6 and 24 h after ischemia. All doses of PJ34 blocked the increase in TNF-alpha at 6 h and 25 mg kg(-1) PJ34 had a sustained effect for up to 24 h. Quantitative real time polymerase chain reaction showed that PJ34 (25 mg kg(-1)) reduced the increase in TNF-alpha mRNA by 70% at 6 h. PJ34 also prevented the increase in mRNAs encoding IL-6 (-41%), E-selectin (-81%) and ICAM-1 (-54%). PJ34 (25 mg kg(-1)) reduced the infarct volume (-26%) and improved neurological deficit, 24 h after ischemia.

CONCLUSIONS AND IMPLICATIONS

PJ34 inhibited the increase in the mRNAs of four inflammatory mediators, caused by cerebral ischemia. The contribution of this effect of PJ34 to neuroprotection remains to be clarified.

The role of matrix metalloproteinase 9 in early neurological worsening of acute lacunar infarction

The involvement of matrix metalloproteinases (MMPs) in ischemic-stroke-induced inflammatory response has recently been suggested; however, the relationship between MMPs and stroke progression has not been evaluated. We investigated the role of MMPs in neurological worsening of acute lacunar infarction. Forty-nine consecutive patients with an acute lacunar infarction (as defined by clinical and MRI criteria within 48 h after stroke onset) were evaluated. Clinical, biochemical, rheological, inflammatory and other parameters were compared between progressive and nonprogressive groups. Among the variables, only inflammatory parameters, including MMP-9 and erythrocyte sedimentation rate, were associated with neurological worsening of acute lacunar infarction (p<0.05). These results suggest that the inflammatory process could play an important role in early neurological worsening of acute lacunar infarction.

An improved post-operative care protocol allows detection of long-term functional deficits following MCAo surgery in rats

Developing new therapeutants for stroke requires animal models in which typical stroke outcomes can be detected. In rats, temporary occlusion of the middle cerebral artery (MCAo) closely resembles reversible human ischemic stroke, but most neuroprotection studies have used limited, short-term (1-2 weeks) behavioural and histological endpoints in this model. Further, the use of this model for assessing long-term recovery has been questioned. Long-term deficits may be difficult to detect because testing may not reflect the diversity of functional outcomes in clinical stroke, and/or high mortality rates mean that only the least severely affected rats remain to be tested. We believe that enhanced survival through intensive post-operative husbandry practices, and extensive behavioural testing that reflects multiple clinically relevant behavioural endpoints, will permit the detection of long-term functional deficits. In the present study, male SD rats (280-320 g) received transient (90 min) MCAo (n = 19) or sham surgery (n = 13). An intense post-operative care protocol was maintained, and assessments included various physical and sensorimotor parameters, tests of emotionality and tests of learning and memory. We report 0% mortality, and statistically significant deficits on all aspects of this battery, including learning and memory deficits up to 2 months post-MCAo. The current study demonstrates that with adequate post-operative care and extensive behavioural testing, assessing the potential of new therapeutants for promoting long-term functional neuroprotection following MCAo in the rat is feasible.