IMM-H004 prevents toxicity induced by delayed treatment of tPA in a rat model of focal cerebral ischemia involving PKA-and PI3K-dependent Akt activation

A modified mouse model of haemorrhagic transformation associated with tPA administration after thromboembolic stroke

Objective

To establish a new mouse model of haemorrhagic transformation associated with delayed tissue-type plasminogen activator (tPA) treatment to provide a novel tool to study therapeutic strategies for haemorrhagic transformation.

Methods

Male C57BL/6 mice were subjected to carotid artery thrombosis stimulated with ferric chloride. The thrombus was then mechanically detached to induce migration toward the intracranial circulation. To induce haemorrhagic transformation, mice were intravenously injected with 10 mg/kg tPA 4.5 h after the onset of ischaemia and were sacrificed 24 h after tPA treatment.

Results

In this new model, administration of tPA 4.5 h after stroke exacerbated the risk of intracerebral haemorrhage. Thrombolysis with tPA also exacerbated cerebral infarction, brain oedema, blood-brain barrier breakdown, and neurological deficits. However, cerebral blood flow was not significantly affected.

Conclusion

The present model is reproducible, easy to perform, and mimics the clinical situation of haemorrhagic transformation after tPA treatment in humans. This modified model can be used as a new tool to test experimental drugs for haemorrhagic transformation associated with delayed tPA administration after an ischaemic stroke.

Verapamil as an Adjunct Therapy to Reduce tPA Toxicity in Hyperglycemic Stroke: Implication of TXNIP/NLRP3 Inflammasome

Thrombolytic therapy has remained quite challenging in hyperglycemic patients for its association with poor prognosis and increased hemorrhagic conversions. We recently showed that tissue plasminogen activator (tPA)-induced cerebrovascular damage is associated with thioredoxin-interacting protein (TXNIP) upregulation, which has an established role in the detrimental effects of hyperglycemia. In the present work, we investigated whether verapamil, an established TXNIP inhibitor, may provide protection against hyperglycemic stroke and tPA-induced blood-brain barrier (BBB) disruption. Acute hyperglycemia was induced by intraperitoneal administration of 20% glucose, 15 min prior to transient middle cerebral artery occlusion (tMCAO). Verapamil (0.15 mg/kg) or saline was intravenously infused with tPA at hyperglycemic reperfusion, 1 h post tMCAO. After 24 h of ischemia/reperfusion (I/R), mice were assessed for neurobehavioral deficits followed by sacrifice and evaluation of brain infarct volume, edema, and microbleeding. Alterations in TXNIP, inflammatory mediators, and BBB markers were further analyzed using immunoblotting or immunostaining techniques. As adjunctive therapy, verapamil significantly reduced tPA-induced BBB leakage, matrix metalloproteinase 9 (MMP-9) upregulation, and tight junction protein deregulation, which resulted in lesser hemorrhagic conversions. Importantly, verapamil strongly reversed tPA-induced TXNIP/NLRP3 (NOD-like receptor pyrin domain-containing-3) inflammasome activation and reduced infarct volume. This concurred with a remarkable decrease in high-mobility group box protein 1 (HMGB-1) and nuclear factor kappa B (NF-κB) stimulation, leading to less priming of NLRP3 inflammasome. This preclinical study supports verapamil as a safe adjuvant that may complement thrombolytic therapy by inhibiting TXNIP's detrimental role in hyperglycemic stroke.

Therapeutic potential of nutraceuticals to protect brain after stroke

Stroke leads to significant neuronal death and long-term neurological disability due to synergistic pathogenic mechanisms. Stroke induces a change in eating habits and in many cases, leads to undernutrition that aggravates the post-stroke pathology. Proper nutritional regimen remains a major strategy to control the modifiable risk factors for cardiovascular and cerebrovascular diseases including stroke. Studies indicate that nutraceuticals (isolated and concentrated form of high-potency natural bioactive substances present in dietary nutritional components) can act as prophylactic as well as adjuvant therapeutic agents to prevent stroke risk, to promote ischemic tolerance and to reduce post-stroke consequences. Nutraceuticals are also thought to regulate blood pressure, delay neurodegeneration and improve overall vascular health. Nutraceuticals potentially mediate these effects by their powerful antioxidant and anti-inflammatory properties. This review discusses the studies that have highlighted the translational potential of nutraceuticals as stroke therapies.

CKLF1/CCR5 axis is involved in neutrophils migration of rats with transient cerebral ischemia

BACKGROUND

Chemokine-like factor 1 (CKLF1) is a chemokine increased significantly in ischemic brain poststroke. It shows chemotaxis effects on various immune cells, but the mechanisms of CKLF1 migrating neutrophils are poorly understood. Recent studies have provided evidence that CC chemokine receptor 5 (CCR5), a receptor of CKLF1, is involved in ischemic stroke.

PURPOSES

To investigate the effects of HIF-1α guided AAV in ischemic brain, investigating the outcome of stroke, and examining the involvement of CKLF1/CCR5 axis in recruitment of neutrophils.

RESULTS

HIF-1α guided AAV knocked down CKLF1 in ischemic area and alleviated brain damage of rats. CKLF1 migrated neutrophils through CCR5, worsening inflammatory responses. Akt/GSK-3β pathway may involve in CKLF1/CCR5 axis guided neutrophils chemotaxis.

CONCLUSIONS

CKLF1/CCR5 axis is involved in neutrophils migration of rats with transient cerebral ischemia. CKLF1/CCR5 axis may be a useful target for stroke therapy.

Tissue Plasminogen Activator Promotes TXNIP-NLRP3 Inflammasome Activation after Hyperglycemic Stroke in Mice

Hyperglycemia has been shown to counterbalance the beneficial effects of tissue plasminogen activator (tPA) and increase the risk of intracerebral hemorrhage in ischemic stroke. Thioredoxin interacting protein (TXNIP) mediates hyperglycemia-induced oxidative damage and inflammation in the brain and reduces cerebral glucose uptake/utilization. We have recently reported that TXNIP-induced NLRP3 (NOD-like receptor pyrin domain-containing-3) inflammasome activation contributes to neuronal damage after ischemic stroke. Here, we tested the hypothesis that tPA induces TXNIP-NLRP3 inflammasome activation after ischemic stroke, in hyperglycemic mice. Acute hyperglycemia was induced in mice by intraperitoneal (IP) administration of a 20% glucose solution. This was followed by transient middle cerebral artery occlusion (t-MCAO), with or without intravenous (IV) tPA administered at reperfusion. The IV-tPA exacerbated hyperglycemia-induced neurological deficits, ipsilateral edema and hemorrhagic transformation, and accentuated peroxisome proliferator activated receptor-γ (PPAR-γ) upregulation and TXNIP/NLRP3 inflammasome activation after ischemic stroke. Higher expression of TXNIP in hyperglycemic t-MCAO animals augmented glucose transporter 1 (GLUT-1) downregulation and increased vascular endothelial growth factor-A (VEGF-A) expression/matrix metallopeptidase 9 (MMP-9) signaling, all of which result in blood brain barrier (BBB) disruption and increased permeability to endogenous immunoglobulin G (IgG). It was also associated with a discernible buildup of nitrotyrosine and accumulation of dysfunctional tight junction proteins: zonula occludens-1 (ZO-1), occludin and claudin-5. Moreover, tPA administration triggered activation of high mobility group box protein 1 (HMGB-1), nuclear factor kappa B (NF-κB), and tumor necrosis factor-α (TNF-α) expression in the ischemic penumbra of hyperglycemic animals. All of these observations suggest a powerful role for TXNIP-NLRP3 inflammasome activation in the tPA-induced toxicity seen with hyperglycemic stroke.

The Effect of Chronic Cerebral Hypoperfusion on Blood-Brain Barrier Permeability in a Transgenic Alzheimer's Disease Mouse Model (PS1V97L)

The blood-brain barrier (BBB) can restrict the therapeutic effects of Alzheimer's disease (AD) medications. While a large number of AD drug treatment trials targeting BBB dynamics have emerged, most have failed due to insufficient permeability. Furthermore, a subset of AD cases, which also feature chronic hypoperfusion are complicated by BBB deficits. We used a mouse model of AD with chronic hypoperfusion-transgenic mice (PS1V97L) with right common carotid artery ligation. In this model, we assessed how chronic cerebral hypoperfusion changed the pathophysiological processes that increase BBB permeability. Compared with control mice, AD mice with chronic hypoperfusion revealed significantly upregulated expression of the receptor for advanced glycation end products (RAGE) on the BBB. Upregulated RAGE caused increased accumulation of amyloid-β (Aβ) in the brain in these mice. Upregulation of RAGE (or binding to Aβ) can promote activation of the NF-κB pathway and enhance oxidative stress and increase the release of pro-inflammatory factors. These factors promoted the reduction of tight junction proteins between the endothelial cells in the BBB and increased its permeability. These findings suggest that the transporter RAGE dysregulation on the BBB initiates a series of pathophysiological processes which lead to increased BBB permeability. Taken together, we have shown that chronic hypoperfusion can serve to enhance and aggravate the BBB impairment in AD.

IMM-H004 therapy for permanent focal ischemic cerebral injury via CKLF1/CCR4-mediated NLRP3 inflammasome activation

Chemokine-like factor 1 (CKLF1) is a potential target for ischemic stroke therapy. The NOD-like receptor protein 3 (NLRP3) inflammasome has been postulated to mediate inflammatory responses during ischemic/reperfusion (I/R) injury. The compound IMM-H004 is a novel coumarin derivative that can improve cerebral I/R injury. This study aims to investigate the effects of IMM-H004 on ischemia stroke injury and further elucidate the molecular mechanisms. The standard pMCAO model of focal ischemia was used in this paper. Drugs were administered at 6 hours after ischemia, and behavioral assessment, euthanasia, and outcome measures were evaluated at 9 hours after ischemia. The effects of IMM-H004 on ischemic stroke injury were determined using 2,3,5-triphenyltetrazolium chloride (TTC) staining, behavioral tests, enzyme-linked immunosorbent assay (ELISA), and Nissl staining. Immunohistologic staining, immunofluorescence staining, quantitative RT-PCR (qPCR), western blotting, and coimmunoprecipitation (CO-IP) assays were used to elucidate the underlying mechanisms. IMM-H004 treatment provided significant protection against ischemia stroke through a CKLF1-dependent anti-inflammatory pathway in rats. IMM-H004 downregulated the amount of CKLF1 binding with C-C chemokine receptor type 4, further suppressing the activation of NLRP3 inflammasome and the following inflammatory response, ultimately protecting the ischemic brain. This preclinical study established the efficacy of IMM-H004 as a potential therapeutic medicine for permanent cerebral ischemia. These results support further efforts to develop IMM-H004 for human clinical trials in acute cerebral ischemia, particularly for patients who are not suitable for reperfusion therapy.

Metabolism of IMM-H004 and Its Pharmacokinetic-Pharmacodynamic Analysis in Cerebral Ischemia/Reperfusion Injured Rats

IMM-H004, a derivative of coumarin, is a promising candidate for the treatment of cerebral ischemia. The pharmacodynamic mechanisms of IMM-H004 are still under exploration. The present study was conducted to explore the pharmacoactive substances of IMM-H004 from the perspective of drug metabolism. Four metabolites of IMM-H004 including demethylated metabolites M1 and M2, glucuronide conjugate IMM-H004G (M3), and sulfated conjugate M4 were found in rats in vivo. IMM-H004G was the major metabolite in rats and cultured human hepatocytes, and uridine diphosphate-glucuronosyltransferase (UGT) was found to catalyze the metabolism of IMM-H004 in human liver microsomes (HLMs) and rat liver microsomes (RLMs) with high capacity (V _max at 3.25 and 5.04 nmol/min/mg protein). Among 13 recombinant human UGT isoforms, UGT1A7, 1A9, 1A8, and 1A1 appeared to be primarily responsible for IMM-H004G formation. The exposure and duration of IMM-H004G (28,948 h × ng/ml of area under the plasma concentration-time curve (AUC), 6.61 h of t _1/2β) was much higher than that of the parent drug (1,638 h × ng/ml of AUC, 0.42 h of t _1/2β) in transient middle cerebral artery occlusion/reperfusion (MCAO/R) rats, consistent with the malondialdehyde (MDA) inhibition effect for at least 10 h. Further pharmacological study revealed that IMM-H004G exhibited a similar neuroprotective activity to that of the parent drug on both oxygen-glucose deprivation injured PC12 cells and transient MCAO/R injured rats. These results demonstrate that both prototype and IMM-H004G are the active pharmaceutical substances, and IMM-H004G, at least in part, contributes to the maintenance of anti-cerebral ischemia efficacy of IMM-H004.

The Effect of Chronic Cerebral Hypoperfusion on Amyloid-β Metabolism in a Transgenic Mouse Model of Alzheimer's Disease (PS1V97L)

Alzheimer's disease (AD) and cerebrovascular disease often coexist. However, it is difficult to determine how chronic cerebral hypoperfusion affects the metabolism of amyloid-β peptides (Aβ) in a living patient with AD. Thus, we developed an animal model of this condition, using transgenic mice (PS1V97L) and right common carotid artery ligation to create chronic cerebral hypoperfusion. The metabolic processes associated with amyloid-β peptide (Aβ) were observed and evaluated in this PS1V97L plus hypoperfusion model. Compared with control mice, the model revealed significantly upregulated expression of Aβ (including Aβ oligomers), with decreased α-secretase activity and expression and increased β-secretase activity and expression. Furthermore, the model revealed increased mRNA and protein expression of the receptor for advanced glycation end products (RAGE) and decreased mRNA and protein expression of low-density lipoprotein receptor-related protein 1 (LRP-1); both these are Aβ transporters. Moreover, the model revealed decreased activity and expression of neprilysin, which is a peripheral Aβ degrading enzyme. These findings suggest that hypoperfusion may magnify the effect of AD on Aβ metabolism by aggravating its abnormal production, transport, and clearance.

IMM-H004 Protects against Cerebral Ischemia Injury and Cardiopulmonary Complications via CKLF1 Mediated Inflammation Pathway in Adult and Aged Rats

(1) Background: Chemokine-like factor 1 (CKLF1) is a chemokine with potential to be a target for stroke therapy. Compound IMM-H004 is a novel coumarin derivative screened from a CKLF1/C-C chemokine receptor type 4 (CCR4) system and has been reported to improve cerebral ischemia/reperfusion injury. This study aims to investigate the protective effects of IMM-H004 on cerebral ischemia injury and its infectious cardiopulmonary complications in adult and aged rats from the CKLF1 perspective. (2) Methods: The effects of IMM-H004 on the protection was determined by 2,3,5-triphenyltetrazolium chloride (TTC) staining, behavior tests, magnetic resonance imaging (MRI) scans, enzyme-linked immunosorbent assay (ELISA), Nissl staining, histo-pathological examination, and cardiopulmonary function detection. Immunohistological staining, immunofluorescence staining, quantitative real-time PCR (qPCR), and western blotting were used to elucidate the underlying mechanisms. (3) Results: IMM-H004 protects against cerebral ischemia induced brain injury and its cardiopulmonary complications, inhibiting injury, and inflammation through CKLF1-dependent anti-inflammation pathway in adult and aged rats. IMM-H004 downregulates the amount of CKLF1, suppressing the followed inflammatory response, and further protects the damaged organs from ischemic injury. (4) Conclusions: The present study suggested that the protective mechanism of IMM-H004 is dependent on CKLF1, which will lead to excessive inflammatory response in cerebral ischemia. IMM-H004 could also be a therapeutic agent in therapy for ischemic stroke and cardiopulmonary complications in the aged population.

Combination therapy for ischemic stroke: Novel approaches to lengthen therapeutic window of tissue plasminogen activator

Tissue plasminogen activator (tPA) thrombolysis continues to be the gold standard therapy for ischemic stroke. Due to the time-limited treatment window, within 4.5 h of stroke onset, and a variety of potentially deadly complications related to delayed administration, particularly hemorrhagic transformation (HT), clinical use of tPA is limited. Combination therapies with other interventions, drug or nondrug, have been hypothesized as a logical approach to enhancing tPA effectiveness. Here, we discuss various potential pharmacological and nondrug treatments to minimize adverse effects, primarily HT, associated with delayed tPA administration. Pharmacological interventions include many that support the integrity of the blood–brain barrier (i.e., atorvastatin, batimastat, candesartan, cilostazol, fasudil, and minocycline), promote vascularization and preserve cerebrovasculature (i.e., coumarin derivative IMM-H004 and granulocyte-colony stimulating factor), employing other mechanisms of action (i.e., oxygen transporters and ascorbic acid). Nondrug treatments are comprised of stem cell transplantation and gas therapies with multi-faceted approaches. Combination therapy with tPA and the aforementioned treatments demonstrated promise for mitigating the adverse complications associated with delayed tPA treatment and rescuing stroke-induced behavioral deficits. Therefore, the conjunctive therapy method is a novel therapeutic approach that can attempt to minimize the limitations of tPA treatment and possibly increase the therapeutic window for ischemic stroke treatment.

Ginkgo biloba extract and its diterpene ginkgolide constituents ameliorate the metabolic disturbances caused by recombinant tissue plasminogen activator in rat prefrontal cortex

INTRODUCTION

Although recombinant tissue plasminogen activator (rtPA) is a widely used therapy in patients with acute ischemic stroke, rtPA-induced toxicity or its adverse effects have been reported in our previous studies. However, Ginkgo biloba extract (GBE) may provide neuroprotective effects against rtPA-induced toxicity. Thus, in the present study, we investigated whether a single administration of rtPA caused neurotoxicity in the prefrontal cortex (PFC) of rats and determined whether GBE or its diterpene ginkgolide (DG) constituents were neuroprotective against any rtPA-induced toxicity.

MATERIALS AND METHODS

We randomly divided adult Sprague-Dawley rats into four groups that were intravenously administered saline, rtPA, rtPA+DG, or rtPA+GBE. The rats were sacrificed 24 hours later and the whole brain removed. A gas chromatography-mass spectrometry metabolomic approach was used to detect molecular changes in the PFC among the groups. Multivariate statistical and pathway analyses were used to determine the relevant metabolites as well as their functions and pathways.

RESULTS

We found 32 metabolites differentially altered in the four groups that were primarily involved in neurotransmitter, amino acid, energy, lipid, and nucleotide metabolism. Our results indicated that a single rtPA administration caused metabolic disturbances in the PFC. Both GBE and DG effectively ameliorated these rtPA-induced disturbances, although DG better controlled the rtPA-induced glutamate and aspartate excitotoxicity and the activation of NMDA receptor.

CONCLUSION

Our results provide important novel mechanistic insights into the adverse effects of rtPA and offer directions for future exploration on the thrombolytic effects of rtPA combined with the administration of DG or GBE for the treatment of acute ischemic stroke in humans.

Targeting vascular inflammation in ischemic stroke: Recent developments on novel immunomodulatory approaches

Ischemic stroke is a devastating and debilitating medical condition with limited therapeutic options. However, accumulating evidence indicates a central role of inflammation in all aspects of stroke including its initiation, the progression of injury, and recovery or wound healing. A central target of inflammation is disruption of the blood brain barrier or neurovascular unit. Here we discuss recent developments in identifying potential molecular targets and immunomodulatory approaches to preserve or protect barrier function and limit infarct damage and functional impairment. These include blocking harmful inflammatory signaling in endothelial cells, microglia/macrophages, or Th17/γδ T cells with biologics, third generation epoxyeicosatrienoic acid (EET) analogs with extended half-life, and miRNA antagomirs. Complementary beneficial pathways may be enhanced by miRNA mimetics or hyperbaric oxygenation. These immunomodulatory approaches could be used to greatly expand the therapeutic window for thrombolytic treatment with tissue plasminogen activator (t-PA). Moreover, nanoparticle technology allows for the selective targeting of endothelial cells for delivery of DNA/RNA oligonucleotides and neuroprotective drugs. In addition, although likely detrimental to the progression of ischemic stroke by inducing inflammation, oxidative stress, and neuronal cell death, 20-HETE may also reduce susceptibility of onset of ischemic stroke by maintaining autoregulation of cerebral blood flow. Although the interaction between inflammation and stroke is multifaceted, a better understanding of the mechanisms behind the pro-inflammatory state at all stages will hopefully help in developing novel immunomodulatory approaches to improve mortality and functional outcome of those inflicted with ischemic stroke.

Pinocembrin Protects Blood-Brain Barrier Function and Expands the Therapeutic Time Window for Tissue-Type Plasminogen Activator Treatment in a Rat Thromboembolic Stroke Model

Tissue-type plasminogen activator (t-PA) remains the only approved therapy for acute ischemic stroke but has a restrictive treatment time window of 4.5 hr. Prolonged ischemia causes blood-brain barrier (BBB) damage and increases the incidence of hemorrhagic transformation (HT) secondary to reperfusion. In this study, we sought to determine the effect of pinocembrin (PCB; a pleiotropic neuroprotective agent) on t-PA administration-induced BBB damage in a novel rat thromboembolic stroke model. By assessing the leakage of Evans blue into the ischemic hemisphere, we demonstrated that PCB pretreatment 5 min before t-PA administration significantly reduced BBB damage following 2 hr, 4 hr, 6 hr, and even 8 hr ischemia. Consistently, PCB pretreatment significantly decreased t-PA infusion-resulting brain edema and infarction volume and improved the behavioral outcomes following 6 hr ischemia. Mechanistically, PCB pretreatment inhibited the activation of MMP-2 and MMP-9 and degradation of tight junction proteins (TJPs) occludin and claudin-5 in the ischemic hemisphere. Moreover, PCB pretreatment significantly reduced phosphorylation of platelet-derived growth factor receptor α (PDGFRα) as compared with t-PA alone. In an in vitro BBB model, PCB decreased transendothelial permeability upon hypoxia/aglycemia through inhibiting PDGF-CC secretion. In conclusion, we demonstrated that PCB pretreatment shortly before t-PA infusion significantly protects BBB function and improves neurological outcomes following prolonged ischemia beyond the regular 4.5 hr t-PA time window. PCB pretreatment may represent a novel means of increasing the safety and the therapeutic time window of t-PA following ischemic stroke.

Salidroside improves brain ischemic injury by activating PI3K/Akt pathway and reduces complications induced by delayed tPA treatment

Cerebral ischemia causes blood-brain barrier (BBB) injury and thus increases the risk of complications secondary to thrombolysis, which limited its clinical application. This study aims to clarify the role and mechanism of salidroside (SALD) in alleviating brain ischemic injury and whether pretreatment of it could improve prognosis of delayed treatment of tissue plasminogen activator (t-PA). Rats were subjected to 3 h of middle cerebral artery occlusion (MCAO) and were intraperitoneally administered with 10, 20 or 40 mg/kg SALD before ischemia. 1.5% 5-triphenyl-2H-tetrazolium chloride (TTC) staining and neurological studies were performed to observe the effectiveness of SALD. The expressions and the distribution of phosphoinositide-3-kinase/protein kinase B (PI3K/Akt) signaling were analyzed. Experiments were further conducted in isolated microvessels and human brain microvascular endothelial cells (HBMECs) to explore the protective mechanism of SALD. Finally, rats were subjected to 6 h of MCAO and 24 h of reperfusion. tPA was given with or without the pretreatment of SALD. Various approaches including gelatin zymography, western blot and immunofluorescence were used to evaluate the effect of this combination therapy. SALD could reduce cerebral ischemic injury and enhance HBMECs viability subjected to OGD. In vivo and in vitro studies showed the mechanism might be related to the activation of PI3K/Akt signaling by phosphorylating Akt on Ser473. Pretreatment of SALD could alleviate BBB injury and improve the outcome of delayed treatment of tPA. These results provide evidence that SALD might be an effective adjuvant to reduce the complications induced by delayed tPA treatment for brain ischemia.

Clinical and Basic Evaluation of the Prognostic Value of Uric Acid in Traumatic Brain Injury

Background: As a major antioxidant in serum, uric acid (UA) was once considered only as the leading cause of gout; however, recent studies have validated its neuroprotective role in ischemic stroke. Because the potential protective effects of UA in traumatic brain injury (TBI) remain largely unknown, this study investigated the role of UA in TBI in both clinical patients and experimental animals. Methods: In TBI patients, serum UA concentrations were measured within 3 days after injury. Clinical outcomes at discharge were classified according to the Glasgow Outcome Scale: good outcome (4-5) and poor outcome (1-3). Risk factors for good outcome were identified via backward logistic regression analysis. For the animal study, a controlled cortical impact (CCI) injury model was established in mice. These mice were given UA at different doses intraperitoneally, and subsequent UA concentrations in mouse serum and brain tissue were determined. Neurological function, oxidative stress, inflammatory response, neuronal maintenance, cerebral blood flow, and lesion size were also assessed. Results: The serum UA level was significantly lower in TBI patients who had a good outcome (P<0.01), and low serum UA was an independent predictor of good outcome after TBI (P<0.01; odds ratio, 0.023; 95% confidence interval, 0.006-0.082). Consistently, decreased levels of serum UA were observed in both TBI patients and CCI animals (P<0.05), whereas the UA concentration was increased in CCI brain tissue (P<0.05). Administration of UA further increased the UA level in brain tissue as compared to that in control animals (P<0.05). Among the different doses administered, 16 mg/kg UA improved sensorimotor functional recovery, spatial learning, and memory in CCI mice (P<0.05). Moreover, oxidative stress and the inflammatory response were inhibited by UA treatment (P<0.05). UA treatment also improved neuronal maintenance and cortical blood flow (P<0.05) but not lesion size (P>0.05). Conclusions: UA acted to attenuate neuronal loss, cerebral perfusion impairment and neurological deficits in TBI mice through suppression of neuronal and vascular oxidative stress. Following TBI, active antioxidant defense in the brain may result in consumption of UA in the serum, and thus, a decreased serum UA level could be predictive of good clinical recovery.

Adjunctive Therapy Approaches for Ischemic Stroke: Innovations to Expand Time Window of Treatment

Tissue plasminogen activator (tPA) thrombolysis remains the gold standard treatment for ischemic stroke. A time-constrained therapeutic window, with the drug to be given within 4.5 h after stroke onset, and lethal side effects associated with delayed treatment, most notably hemorrhagic transformation (HT), limit the clinical use of tPA. Co-administering tPA with other agents, including drug or non-drug interventions, has been proposed as a practical strategy to address the limitations of tPA. Here, we discuss the pharmacological and non-drug approaches that were examined to mitigate the complications-especially HT-associated with delayed tPA treatment. The pharmacological treatments include those that preserve the blood-brain barrier (e.g., atovarstatin, batimastat, candesartan, cilostazol, fasudil, minocycline, etc.), enhance vascularization and protect the cerebrovasculature (e.g., coumarin derivate IMM-H004 and granulocyte-colony stimulating factor (G-CSF)), and exert their effects through other modes of action (e.g., oxygen transporters, ascorbic acid, etc.). The non-drug approaches include stem cell treatments and gas therapy with multi-pronged biological effects. Co-administering tPA with the abovementioned therapies showed promise in attenuating delayed tPA-induced side effects and stroke-induced neurological and behavioral deficits. Thus, adjunctive treatment approach is an innovative therapeutic modality that can address the limitations of tPA treatment and potentially expand the time window for ischemic stroke therapy.

NAD replenishment with nicotinamide mononucleotide protects blood-brain barrier integrity and attenuates delayed tissue plasminogen activator-induced haemorrhagic transformation after cerebral ischaemia

BACKGROUND AND PURPOSE

Tissue plasminogen activator (tPA) is the only approved pharmacological therapy for acute brain ischaemia; however, a major limitation of tPA is the haemorrhagic transformation that follows tPA treatment. Here, we determined whether nicotinamide mononucleotide (NMN), a key intermediate of nicotinamide adenine dinucleotide biosynthesis, affects tPA-induced haemorrhagic transformation.

EXPERIMENTAL APPROACH

Middle cerebral artery occlusion (MCAO) was achieved in CD1 mice by introducing a filament to the left MCA for 5 h. When the filament was removed for reperfusion, tPA was infused via the tail vein. A single dose of NMN was injected i.p. (300 mg·kg^-1 ). Mice were killed at 24 h post ischaemia, and their brains were evaluated for brain infarction, oedema, haemoglobin content, apoptosis, neuroinflammation, blood-brain barrier (BBB) permeability, the expression of tight junction proteins (TJPs) and the activity/expression of MMPs.

KEY RESULTS

In the mice infused with tPA at 5 h post ischaemia, there were significant increases in mortality, brain infarction, brain oedema, brain haemoglobin level, neural apoptosis, Iba-1 staining (microglia activation) and myeloperoxidase staining (neutrophil infiltration). All these tPA-induced alterations were significantly prevented by NMN administration. Mechanistically, the delayed tPA treatment increased BBB permeability by down-regulating TJPs, including claudin-1, occludin and zonula occludens-1, and enhancing the activities and protein expression of MMP9 and MMP2. Similarly, NMN administration partly blocked these tPA-induced molecular changes.

CONCLUSIONS AND IMPLICATIONS

Our results demonstrate that NMN ameliorates tPA-induced haemorrhagic transformation in brain ischaemia by maintaining the integrity of the BBB.

Regulatory T cells ameliorate tissue plasminogen activator-induced brain haemorrhage after stroke

Delayed thrombolytic treatment with recombinant tissue plasminogen activator (tPA) may exacerbate blood-brain barrier breakdown after ischaemic stroke and lead to lethal haemorrhagic transformation. The immune system is a dynamic modulator of stroke response, and excessive immune cell accumulation in the cerebral vasculature is associated with compromised integrity of the blood-brain barrier. We previously reported that regulatory T cells, which function to suppress excessive immune responses, ameliorated blood-brain barrier damage after cerebral ischaemia. This study assessed the impact of regulatory T cells in the context of tPA-induced brain haemorrhage and investigated the underlying mechanisms of action. The number of circulating regulatory T cells in stroke patients was dramatically reduced soon after stroke onset (84 acute ischaemic stroke patients with or without intravenous tPA treatment, compared to 115 age and gender-matched healthy controls). Although stroke patients without tPA treatment gradually repopulated the numbers of circulating regulatory T cells within the first 7 days after stroke, post-ischaemic tPA treatment led to sustained suppression of regulatory T cells in the blood. We then used the murine suture and embolic middle cerebral artery occlusion models of stroke to investigate the therapeutic potential of adoptive regulatory T cell transfer against tPA-induced haemorrhagic transformation. Delayed administration of tPA (10 mg/kg) resulted in haemorrhagic transformation in the ischaemic territory 1 day after ischaemia. When regulatory T cells (2 × 106/mouse) were intravenously administered immediately after delayed tPA treatment in ischaemic mice, haemorrhagic transformation was significantly decreased, and this was associated with improved sensorimotor functions. Blood-brain barrier disruption and tight junction damages were observed in the presence of delayed tPA after stroke, but were mitigated by regulatory T cell transfer. Mechanistic studies demonstrated that regulatory T cells completely abolished the tPA-induced elevation of MMP9 and CCL2 after stroke. Using MMP9 and CCL2 knockout mice, we discovered that both molecules partially contributed to the protective actions of regulatory T cells. In an in vitro endothelial cell-based model of the blood-brain barrier, we confirmed that regulatory T cells inhibited tPA-induced endothelial expression of CCL2 and preserved blood-brain barrier integrity after an ischaemic challenge. Lentivirus-mediated CCL2 knockdown in endothelial cells completely abolished the blood-brain barrier protective effect of regulatory T cells in vitro. Altogether, our studies suggest that regulatory T cell adoptive transfer may alleviate thrombolytic treatment-induced haemorrhage in stroke victims. Furthermore, regulatory T cell-afforded protection in the tPA-treated stroke model is mediated by two inhibitory mechanisms involving CCL2 and MMP9. Thus, regulatory T cell adoptive transfer may be useful as a cell-based therapy to improve the efficacy and safety of thrombolytic treatment for ischaemic stroke.

Determination of IMM-H004, a novel neuroprotective agent, in rat plasma and brain tissue by liquid chromatography-tandem mass spectrometry

A rapid and sensitive liquid chromatography-tandem mass spectrometry method for determination of IMM-H004, a novel neuroprotective agent, in rat plasma and brain was developed. Plasma and brain tissue homogenate samples containing IMM-H004 and propranolol (internal standard, IS) were prepared by using a direct protein precipitation of acetonitrile. Separation was carried out in Zorbax SB-C18 column at a flow rate of 0.3mL/min utilizing acetonitrile/water as mobile phases which contain 0.5% formic acid (v/v). Triple quadrupole mass spectrometer was used for detection with selective reaction monitoring. The mass transition ion-pairs were 305→248 for IMM-H004 and 260→183 for IS in positive ion mode. The linear ranges of IMM-H004 were 5-1000ng/mL in plasma and 1-200ng/mL in brain tissue homogenate. The intra- and inter-day precisions were within ±14.9% for analyte in both matrices (±17.0% at the lowest limit of quantification level), while the deviation of assay accuracy was within ±12.9%. No obvious matrix effect was observed. The recovery of the analyte was higher than 85.3%. IMM-H004 was stable during the whole analytic process. The method was applied successfully to the plasma and brain pharmacokinetic study of IMM-H004 in rats after a single intravenous administration.

Strategies to Extend Thrombolytic Time Window for Ischemic Stroke Treatment: An Unmet Clinical Need

To date, reperfusion with tissue plasminogen activator (tPA) remains the gold standard treatment for ischemic stroke. However, when tPA is given beyond 4.5 hours of stroke onset, deleterious effects of the drug ensue, especially, hemorrhagic transformation (HT), which causes the most significant morbidity and mortality in stroke patients. An important clinical problem at hand is to develop strategies that will enhance the therapeutic time window for tPA therapy and reduce the adverse effects (especially HT) of delayed tPA treatment. We reviewed the pharmacological agents which reduced the risk of HT associated with delayed (beyond 4.5 hours post-stroke) tPA treatment in preclinical studies, which we classified into those that putatively preserve the blood-brain barrier (e.g., minocycline, cilostazol, fasudil, candesartan, and bryostatin) and/or enhance vascularization and protect the cerebrovasculature (e.g., coumarin derivate IMM-H004 and granulocyte colony-stimulating factor). Recently, other new therapeutic modalities (e.g., oxygen transporters) have been reported which improved delayed tPA-associated outcomes by acting through other mechanisms. While the above-mentioned interventions unequivocally reduced delayed tPA-induced HT in stroke models, the long-term efficacy of these drugs are not yet established. Further optimization is required to expedite their future clinical application. The findings from this review indicate the need to explore the most ideal adjunctive interventions that will not only reduce delayed tPA–induced HT, but also preserve neurovascular functions. While waiting for the next breakthrough drug in acute stroke treatment, it is equally important to allocate considerable effort to find approaches to address the limitations of the only FDA-approved stroke therapy.

IMM-H004, a coumarin derivative, attenuated brain ischemia/reperfusion injuries and subsequent inflammation in spontaneously hypertensive rats through inhibition of VCAM-1

We studied the effect of IMM-H004 in treating brain I/R injury in spontaneously hypertensive rats and showed that IMM-H004 could efficiently ameliorate neurological defects and infarct volume in a time and dose dependent manner.

Neuroprotective effects of Aceglutamide on motor function in a rat model of cerebral ischemia and reperfusion

PURPOSE

To investigate the effect and underlying mechanism of Aceglutamide on motor dysfunction in rats after cerebral ischemia-reperfusion.

METHODS

Adult male Sprague-Dawley rats were subjected to 2 h transient middle cerebral artery occlusion (MCAO). Aceglutamide or vehicle was intraperitoneally given to rats at 24 h after reperfusion and lasted for 14 days. Subsequently functional recovery was assessed and number of tyrosine hydroxylase (TH)-positive neurons in substantia nigra (SN) was analyzed. Tumor necrosis factor receptor-associated factor 1(TRAF1), P-Akt and Bcl-2/Bax were determined in mesencephalic tissue by Western blot method. PC12 cells and primary cultured mesencephalic neurons were employed to further investigate the mechanism of Aceglutamide.

RESULTS

Aceglutamide treatment improved behavioral functions, reduced the infarction volume, and elevated the number of TH-positive neurons in the SN. Moreover, Aceglutamide significantly attenuated neuronal apoptosis in the SN. Meanwhile Aceglutamide treatment significantly inhibited the expression of TRAF1 and up-regulated the expression of P-Akt and Bcl-2/Bax ratio both in vitro and in vivo.

CONCLUSIONS

Aceglutamide ameliorated motor dysfunction and delayed neuronal death in the SN after ischemia, which involved the inhibition of pro-apoptotic factor TRAF1 and activation of Akt/Bcl-2 signaling pathway. These data provided experimental information for applying Aceglutamide to ischemic stroke treatment.

Recombinant Tissue Plasminogen Activator Induces Neurological Side Effects Independent on Thrombolysis in Mechanical Animal Models of Focal Cerebral Infarction: A Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

Recombinant tissue plasminogen activator (rtPA) is the only effective drug approved by US FDA to treat ischemic stroke, and it contains pleiotropic effects besides thrombolysis. We performed a meta-analysis to clarify effect of tissue plasminogen activator (tPA) on cerebral infarction besides its thrombolysis property in mechanical animal stroke.

METHODS

Relevant studies were identified by two reviewers after searching online databases, including Pubmed, Embase, and ScienceDirect, from 1979 to 2016. We identified 6, 65, 17, 12, 16, 12 and 13 comparisons reporting effect of endogenous tPA on infarction volume and effects of rtPA on infarction volume, blood-brain barrier, brain edema, intracerebral hemorrhage, neurological function and mortality rate in all 47 included studies. Standardized mean differences for continuous measures and risk ratio for dichotomous measures were calculated to assess the effects of endogenous tPA and rtPA on cerebral infarction in animals. The quality of included studies was assessed using the Stroke Therapy Academic Industry Roundtable score. Subgroup analysis, meta-regression and sensitivity analysis were performed to explore sources of heterogeneity. Funnel plot, Trim and Fill method and Egger's test were obtained to detect publication bias.

RESULTS

We found that both endogenous tPA and rtPA had not enlarged infarction volume, or deteriorated neurological function. However, rtPA would disrupt blood-brain barrier, aggravate brain edema, induce intracerebral hemorrhage and increase mortality rate.

CONCLUSIONS

This meta-analysis reveals rtPA can lead to neurological side effects besides thrombolysis in mechanical animal stroke, which may account for clinical exacerbation for stroke patients that do not achieve vascular recanalization with rtPA.

Intravenous high mobility group box 1 upregulates the expression of HIF-1α in the myocardium via a protein kinase B-dependent pathway in rats following acute myocardial ischemia

The effects of intravenous high mobility group box 1 (HMGB1) on myocardial ischemia/reperfusion (I/R) injury remains to be elucidated. The purpose of the present study was to investigate the effects of intravenous HMGB1 on the expression of hypoxia inducible factor-1α (HIF-1α) in the myocardium of rats following acute myocardial ischemia, and to examine the effects of intravenous HMGB1 on myocardial I/R injury. Male Wistar rats were divided into the following groups: Sham operation group (n=10), a group exposed to ischemia for 30 min and reperfusion for 4 h (I/R group) as a control (n=10), an HMGB group, in which 100 ng/kg HMGB was administered intravenously 30 min prior to ischemia (n=10), an LY group, in whic LY294002, an inhibitor of phosphoinositide 3-kinase (PI3K), was administered intravenously (0.3 mg/kg) 40 min prior to ischemia (n=10), and the HMGB1+LY group, in which HMGB1 (100 ng/kg) and LY294002 (0.3 mg/kg) were administered intravenously 30 min and 40 min prior to ischemia, respectively (n=10). The serum levels of cardiac troponin I (cTnI) and tumor necrosis factor-α (TNF-α), and myocardial infarct size were measured. The expression levels of phosphorylated Akt and HIF-1α were investigated using western blot analyses. The results showed that pre-treatment with HMGB1 significantly decreased serum levels of cTnI, and TNF-α, and reduced myocardial infarct size following 4 h reperfusion (all P<0.05). HMGB1 also increased the expression levels of HIF-1α and p-Akt induced by I/R (P<0.05). LY294002 was found to eliminate the effects of intravenous HMGB1 on myocardial I/R injury (P<0.05). These results suggest that intravenous pre-treatment with HMGB1 may exert its cardioprotective effects via the upregulation of the myocardial expression of HIF-1α, which may be regulated by the PI3K/Akt signaling pathway, in rats following acute myocardial I/R.

Compound IMM-H004, a novel coumarin derivative, protects against CA1 cell loss and spatial learning impairments resulting from transient global ischemia

AIMS

Compound IMM-H004 (7-hydroxy-5-methoxy-4-methyl-3-[4-methylpiperazin-1-yl]-2H-chromen-2-one) is a new synthetic derivative of coumarin, and previous studies showed that it exhibited antioxidant and neuroprotective roles in focal cerebral ischemia. However, we know little about the compound's function in transient global ischemia. This study is to investigate whether compound IMM-H004 can protect against transient global ischemic injury.

METHODS

Four-vessel occlusion (4VO) rat model was induced for a 20-min occlusion and different times of reperfusion to mimic transient global cerebral ischemia. IMM-H004 (3, 6, 9 mg/kg) or Edaravone (6 mg/kg) was administered after 30 min of reperfusion. Morris water maze tests were used to estimate the ability of spatial learning and memory. Nissl staining, TUNEL assay and Immunoblot for Bax/Bcl-2 and activated caspase-3 were used to detect hippocampal neuron injury. Immunoblot for PSD-95 and synapsin 1, and electron microscopy were used to observe synaptic function.

RESULTS

Compared with vehicle group, IMM-H004 significantly improved the spatial learning performance and exhibited less CA1 neurons loss. The expressions of Bax/Bcl-2 and activated caspase-3 were decreased. IMM-H004 also ameliorated synaptic structure, decreased PSD-95 and increased synapsin 1 expression.

CONCLUSION

These findings suggested that IMM-H004 exerted neuroprotective role in global ischemia by reducing apoptosis and maintaining the integrity of synaptic structure.

Adipose stem cells promote smooth muscle cells to secrete elastin in rat abdominal aortic aneurysm

Background

Abdominal aortic aneurysm (AAA) is a life-threatening disease and its prevalence rate increases with social aging. The degradation of elastic is an important factor in the formation of AAA.

Methods

Adipose derived stem cells (ADSCs) and bone marrow mesenchymal stem cells (BMSCs) were isolated from rats, and identified by Oil red O and alizarin red staining after adipogenesis and osteogenesis induction. In addition, ADSCs were also identified by flow cytometry with CD markers. AAA model in rats was established, and smooth muscle cells (SMCs) were isolated from AAA aortic wall and identified by immunohistochemistry. ADSCs or BMSCs were co-cultured with AAA aortic wall for in vitro experiment, and ADSCs were injected into AAA model for in vivo test. Then orcein staining was used for observing the morphology of elastic fiber, Western blot and real-time PCR were used respectively to detect the protein and gene expression of elastin, gelatinases spectrum analysis was used to detect the activity of matrix metalloproteinase-2 (MMP-2) and MMP-9.

Results

Lots of red lipid droplets were visible by Oil red O staining after adipogenesis induction, and black calcium nodules appeared by alizarin red staining after osteogenesis induction. The results of flow cytometry showed that ADSCs expressed CD44 and CD105, but exhibited negligible expression of CD31 and CD45. SMCs exhibited spindle-like morphology and α-actin protein was positive in cytoplasm. After co-cultured with ADSCs or BMSCs, the elastic fiber recovered normal winding shape, both the gene and protein expression of elastin increased, and the activity of MMP-2 decreased. The in vivo result was similar to that of in vitro.

Conclusions

ADSCs promote the expression of elastin in SMCs and contribute to the reconstruction of elastic fiber, which may provide new ideas for treating AAA.