Niaspan reduces high-mobility group box 1/receptor for advanced glycation endproducts after stroke in type-1 diabetic rats

Ischemic stroke and diabetes: a TLR4-mediated neuroinflammatory perspective

Ischemic stroke is the major contributor to morbidity and mortality in people with diabetes mellitus. In ischemic stroke patients, neuroinflammation is now understood to be one of the main underlying mechanisms for cerebral damage and recovery delay. It has been well-established that toll-like receptor 4 (TLR4) signaling pathway plays a key role in neuroinflammation. Emerging research over the last decade has revealed that, compared to ischemic stroke without diabetes mellitus, ischemic stroke with diabetes mellitus significantly upregulates TLR4-mediated neuroinflammation, increasing the risk of cerebral and neuronal damage as well as neurofunctional recovery delay. This review aims to discuss how ischemic stroke with diabetes mellitus amplifies TLR4-mediated neuroinflammation and its consequences. Additionally covered in this review is the potential application of TLR4 antagonists in the management of diabetic ischemic stroke.

Melatonin mitigates type 1 diabetes-aggravated cerebral ischemia-reperfusion injury through anti-inflammatory and anti-apoptotic effects

INTRODUCTION

Cerebral ischemia and diabetes mellitus (DM) are common diseases that often coexist and interact with each other. DM doubles the risk of ischemic stroke, and cerebral ischemia causes stress-induced hyperglycemia. Most experimental stroke studies used healthy animals. Melatonin is neuroprotective against cerebral ischemia-reperfusion injury (CIRI) in non-DM, normoglycemic animals through anti-oxidant effect, anti-inflammation, and anti-apoptosis. Previous studies have also reported a negative correlation between hyperglycemia and urinary melatonin metabolite.

OBJECTIVES

The present study investigated the effects of type 1 DM (T1DM) on CIRI in rats and the role of melatonin against CIRI in T1DM animals.

RESULTS

Our results revealed that T1DM aggravated CIRI, leading to greater weight loss, increased infarct volume, and worse neurological deficit. T1DM aggravated the post-CIRI activation of nuclear factor kappa B (NF-κB) pathway and increase in pro-apoptotic markers. A single intraperitoneal injection of melatonin at 10 mg/kg given 30 min before ischemia onset attenuated CIRI in T1DM rats, resulting in less weight loss, decreased infarct volume, and milder neurological deficit when compared with the vehicle group. Melatonin treatment achieved anti-inflammatory and anti-apoptotic effects with reduced NF-κB pathway activation, reduced mitochondrial cytochrome C release, decreased calpain-mediated spectrin breakdown product (SBDP), and decreased caspase-3-mediated SBDP. The treatment also led to fewer iNOS+ cells, milder CD-68+ macrophage/microglia infiltration, decreased TUNEL+ apoptotic cells, and better neuronal survival.

CONCLUSIONS

T1DM aggravates CIRI. Melatonin treatment is neuroprotective against CIRI in T1DM rats via anti-inflammatory and anti-apoptotic effects.

Post-Stroke Administration of L-4F Promotes Neurovascular and White Matter Remodeling in Type-2 Diabetic Stroke Mice

Patients with type 2 diabetes mellitus (T2DM) exhibit a distinct and high risk of ischemic stroke with worse post-stroke neurovascular and white matter (WM) prognosis than the non-diabetic population. In the central nervous system, the ATP-binding cassette transporter member A 1 (ABCA1), a reverse cholesterol transporter that efflux cellular cholesterol, plays an important role in high-density lipoprotein (HDL) biogenesis and in maintaining neurovascular stability and WM integrity. Our previous study shows that L-4F, an economical apolipoprotein A member I (ApoA-I) mimetic peptide, has neuroprotective effects via alleviating neurovascular and WM impairments in the brain of db/db-T2DM stroke mice. To further investigate whether L-4F has neurorestorative benefits in the ischemic brain after stroke in T2DM and elucidate the underlying molecular mechanisms, we subjected middle-aged, brain-ABCA1 deficient (ABCA1-B/-B), and ABCA1-floxed (ABCA1fl/fl) T2DM control mice to distal middle cerebral artery occlusion. L-4F (16 mg/kg, subcutaneous) treatment was initiated 24 h after stroke and administered once daily for 21 days. Treatment of T2DM-stroke with L-4F improved neurological functional outcome, and decreased hemorrhage, mortality, and BBB leakage identified by decreased albumin infiltration and increased tight-junction and astrocyte end-feet densities, increased cerebral arteriole diameter and smooth muscle cell number, and increased WM density and oligodendrogenesis in the ischemic brain in both ABCA1-B/-B and ABCA1fl/fl T2DM-stroke mice compared with vehicle-control mice, respectively (p < 0.05, n = 9 or 21/group). The L-4F treatment reduced macrophage infiltration and neuroinflammation identified by decreases in ED-1, monocyte chemoattractant protein-1 (MCP-1), and toll-like receptor 4 (TLR4) expression, and increases in anti-inflammatory factor Insulin-like growth factor 1 (IGF-1) and its receptor IGF-1 receptor β (IGF-1Rβ) in the ischemic brain (p < 0.05, n = 6/group). These results suggest that post-stroke administration of L-4F may provide a restorative strategy for T2DM-stroke by promoting neurovascular and WM remodeling. Reducing neuroinflammation in the injured brain may contribute at least partially to the restorative effects of L-4F independent of the ABCA1 signaling pathway.

Intracerebral Hemorrhage and Diabetes Mellitus: Blood-Brain Barrier Disruption, Pathophysiology, and Cognitive Impairments

There is a surge in diabetes incidence with an estimated 463 million individuals been diagnosed worldwide. Diabetes Mellitus (DM) is a major stroke-related comorbid condition that increases the susceptibility of disabling post-stroke outcomes. Although less common, intracerebral hemorrhage (ICH) is the most dramatic subtype of stroke that is associated with higher mortality, particularly in DM population. Previous studies have focused mainly on the impact of DM on ischemic stroke. Few studies have focused on impact of DM on ICH and discussed the blood-brain barrier disruption, brain edema, and hematoma formation. However, more recently, investigating the role of oxidative damage and reactive oxygen species (ROS) production in preclinical studies involving DM-ICH animal models has gained attention. But, little is known about the correlation between neuroinflammatory processes, glial cells activation, and peripheral immune cell invasion with DM-ICH injury. DM and ICH patients experience impaired abilities in multiple cognitive domains by relatively comparable mechanisms, which could get exacerbated in the setting of comorbidities. In this review, we discuss both the pathology of DM as a comorbid condition for ICH and the potential molecular therapeutic targets for the clinical management of the ICH and its recovery.

Association of RAGE with acute ischemic stroke prognosis in type 2 diabetes

BACKGROUND

In experimental models, the receptor for advanced glycation end products (RAGE) has been reported as a key mediator in cerebral ischemia. In this study, the clinical significance of serum RAGE levels in acute ischemic stroke patients with type 2 diabetes was determined.

METHOD

Three hundred seven patients (165 patients without diabetes and 142 patients with diabetes) with acute cerebral infarction (ACI) were enrolled over 3 consecutive months. On admission, their National Institute of Health Stroke Scale (NIHSS) scores were recorded. The clinical laboratory data of all subjects were collected, and their serum levels of RAGE were assayed using enzyme-linked immunosorbent assay (ELISA). On admission and 3 months after stroke, the clinical outcomes were assessed using the Barthel index (BI) and modified Rankin scale (mRS).

RESULTS

Patients with diabetes (PwD) had significantly higher levels of triglycerides (TGs), RAGE, fasting blood glucose (FBG), glycosylated hemoglobin A1c (HbA1c), and worse stroke prognosis than patients without diabetes (p < 0.05). Hypertension history, RAGE, and FBG in patients without diabetes in ischemic stroke were increased, relative to stroke prognosis. Weight, RAGE, and FBG data showed significant correlation with stroke outcome in PwD (p < 0.05). Multiple logistic regression analysis indicated that the RAGE level was an independent risk factor for poor prognosis of stroke, especially in PwD with ACI (p < 0.05).

CONCLUSION

Acute ischemic stroke is associated with elevated serum RAGE level, which, at admission, is an independent predictor of poor outcome for stroke in type 2 diabetes.

Role of HMGB1 in the Interplay between NETosis and Thrombosis in Ischemic Stroke: A Review

Neutrophil extracellular traps (NETs) comprise decondensed chromatin, histones and neutrophil granular proteins and are involved in the response to infectious as well as non-infectious diseases. The prothrombotic activity of NETs has been reported in various thrombus-related diseases; this activity can be attributed to the fact that the NETs serve as a scaffold for cells and numerous coagulation factors and stimulate fibrin deposition. A crosstalk between NETs and thrombosis has been indicated to play a role in numerous thrombosis-related conditions including stroke. In cerebral ischemia, neutrophils are the first group of cells to infiltrate the damaged brain tissue, where they produce NETs in the brain parenchyma and within blood vessels, thereby aggravating inflammation. Increasing evidences suggest the connection between NETosis and thrombosis as a possible cause of “tPA resistance”, a problem encountered during the treatment of stroke patients. Several damage-associated molecular pattern molecules have been proven to induce NETosis and thrombosis, with high mobility group box 1 (HMGB1) playing a critical role. This review discusses NETosis and thrombosis and their crosstalk in various thrombosis-related diseases, focusing on the role of HMGB1 as a mediator in stroke. We also addresses the function of peptidylarginine deiminase 4 with respect to the interplay with HMGB1 in NET-induced thrombosis.

High Mobility Group Box-1 and Diabetes Mellitus Complications: State of the Art and Future Perspectives

Diabetes mellitus (DM) is an endemic disease, with growing health and social costs. The complications of diabetes can affect potentially all parts of the human body, from the heart to the kidneys, peripheral and central nervous system, and the vascular bed. Although many mechanisms have been studied, not all players responsible for these complications have been defined yet. High Mobility Group Box-1 (HMGB1) is a non-histone nuclear protein that has been implicated in many pathological processes, from sepsis to ischemia. The purpose of this review is to take stock of all the most recent data available on the role of HMGB1 in the complications of DM.

ApoA-I Mimetic Peptide Reduces Vascular and White Matter Damage After Stroke in Type-2 Diabetic Mice

Diabetes leads to an elevated risk of stroke and worse functional outcome compared to the general population. We investigate whether L-4F, an economical ApoA-I mimetic peptide, reduces neurovascular and white-matter damage in db/db type-2 diabetic (T2DM) stroke mice. L-4F (16 mg/kg, subcutaneously administered initially 2 h after stroke and subsequently daily for 4 days) reduced hemorrhagic transformation, decreased infarct-volume and mortality, and treated mice exhibited increased cerebral arteriole diameter and smooth muscle cell number, decreased blood-brain barrier leakage and white-matter damage in the ischemic brain as well as improved neurological functional outcome after stroke compared with vehicle-control T2DM mice (p < 0.05, n = 11/group). Moreover, administration of L-4F mitigated macrophage infiltration, and reduced the level of proinflammatory mediators tumor necrosis factor alpha (TNFα), high-mobility group box-1 (HMGB-1)/advanced glycation end-product receptor (RAGE) and plasminogen activator inhibitor-1 (PAI-1) in the ischemic brain in T2DM mice (p < 0.05, n = 6/group). In vitro, L-4F treatment did not increase capillary-like tube formation in mouse-brain endothelial cells, but increased primary artery explant cell migration derived from C57BL/6-aorta 1 day after middle cerebral artery occlusion (MCAo), and enhanced neurite-outgrowth after 2 h of oxygen-glucose deprivation and axonal-outgrowth in primary cortical neurons derived from the C57BL/6-embryos subjected to high-glucose condition. This study suggests that early treatment with L-4F provides a potential strategy to reduce neuroinflammation and vascular and white-matter damage in the T2DM stroke population.

The Receptor for Advanced Glycation End Products (RAGE) and DIAPH1: Implications for vascular and neuroinflammatory dysfunction in disorders of the central nervous system

The Receptor for Advanced Glycation End Products (RAGE) is expressed by multiple cell types in the brain and spinal cord that are linked to the pathogenesis of neurovascular and neurodegenerative disorders, including neurons, glia (microglia and astrocytes) and vascular cells (endothelial cells, smooth muscle cells and pericytes). Mounting structural and functional evidence implicates the interaction of the RAGE cytoplasmic domain with the formin, Diaphanous1 (DIAPH1), as the key cytoplasmic hub for RAGE ligand-mediated activation of cellular signaling. In aging and diabetes, the ligands of the receptor abound, both in the central nervous system (CNS) and in the periphery. Such accumulation of RAGE ligands triggers multiple downstream events, including upregulation of RAGE itself. Once set in motion, cell intrinsic and cell-cell communication mechanisms, at least in part via RAGE, trigger dysfunction in the CNS. A key outcome of endothelial dysfunction is reduction in cerebral blood flow and increased permeability of the blood brain barrier, conditions that facilitate entry of activated leukocytes into the CNS, thereby amplifying primary nodes of CNS cellular stress. This contribution details a review of the ligands of RAGE, the mechanisms and consequences of RAGE signal transduction, and cites multiple examples of published work in which RAGE contributes to the pathogenesis of neurovascular perturbation. Insights into potential therapeutic modalities targeting the RAGE signal transduction axis for disorders of CNS vascular dysfunction and neurodegeneration are also discussed.

Angiopoietin-1 Mimetic Peptide Promotes Neuroprotection after Stroke in Type 1 Diabetic Rats

Angiopoietin-1 (Ang1) mediates vascular maturation and immune response. Diabetes decreases Ang1 expression and disrupts Ang1/Tie2 signaling activity. Vasculotide is an Ang1 mimetic peptide, and has anti-inflammatory effects. In this study, we test the hypothesis that vasculotide treatment induces neuroprotection and decreases inflammation after stroke in type 1 diabetic (T1DM) rats. T1DM rats were subjected to embolic middle cerebral artery occlusion (MCAo) and treated with: 1) phosphate buffered saline (PBS); 2) vasculotide (3µg/kg, i.p. injection) administered half an hour prior to MCAo and at 8 and 24 hours after MCAo. Rats were sacrificed at 48 h after MCAo. Neurological function, infarct volume, hemorrhage, blood brain barrier (BBB) permeability and neuroinflammation were measured. Vasculotide treatment of T1DM-MCAo rats significantly improves functional outcome, decreases infarct volume and BBB permeability, but does not decrease brain hemorrhagic transformation compared with PBS-treated T1DM-MCAo rats. In the ischemic brain, Vasculotide treatment significantly decreases apoptosis, number of cleaved-caspase-3 positive cells, the expression of monocyte chemotactic protein-1 (MCP-1) and tumor necrosis factor (TNF-α). Western blot analysis shows that vasculotide significantly decreases expression of receptor for advanced glycation end products (RAGE), MCP-1 and TNF-α in the ischemic brain compared with T1DM-MCAo rats. Vasculotide treatment in cultured primary cortical neurons (PCN) significantly decreases TLR4 expression compared with control. Decreased neuroinflammation and reduced BBB leakage may contribute, at least in part, to vasculotide-induced neuroprotective effects after stroke in T1DM rats.

DNA binding protein HMGB1 secreted by activated microglia promotes the apoptosis of hippocampal neurons in diabetes complicated with OSA

Type 2 diabetes mellitus (T2DM) complicated with obstructive sleep apnea (OSA) may cause neuronal apoptosis and cognitive deficits, but the underlying mechanisms remain unclear. We aimed to determine the relationship between the activation of microglia and the apoptosis of hippocampal neurons, specifically in terms of high mobility group box-1 (HMGB1), after high glucose (HG) and intermittent hypoxia (IH) exposure. Diabetic KK-Ay mice and non-diabetic C57BL/6J mice (C57 mice) underwent IH or normoxia (control) exposure for 4 weeks. Cognitive function, microglial activation and hippocampal neuronal apoptosis were assessed after IH or normoxia exposure. Compared with C57 control mice, KK-Ay control mice exhibited increased cognitive dysfunction, microglial activation and hippocampal neuronal apoptosis. There were no differences between untreated KK-Ay control mice and C57 mice that had been exposed to IH. The abovementioned responses were aggravated in IH-exposed KK-Ay mice compared with control KK-Ay mice. In vitro, a cellular co-culture experiment showed that HG combined with IH could activate BV2 microglia, leading to the release of neuroinflammatory factors (ROS, TNF-α, IL-1β) and mediating the apoptosis of HT22 cells via the PI3K/Akt/GSK-3β signaling pathway. Meanwhile, HMGB1 was actively secreted into the extracellular environment from activated BV2 microglia. As a proinflammatory factor, it was able to sustain microglial activation by directly acting on those cells. The activation promoted positive feedback and aggravated neuronal damage further. In a cellular monoculture or co-culture system, HMGB1 siRNA was able to alleviate the activation of BV2 cells and the apoptosis of HT22 cells induced by HG combined with IH. Our object is to show that inhibition of HMGB1 may break the vicious cycle to prevent or treat neuroinflammation and hippocampal neuronal apoptosis caused by T2DM complicated with OSA.

Back to Basics: Adherence With Guidelines for Glucose and Temperature Control in an American Comprehensive Stroke Center Sample

BACKGROUND

Variance from guideline-directed care for glucose and temperature control remains unknown in the United States at a time when priorities have shifted to ensure rapid diagnosis and treatment of acute stroke patients. However, protocol-driven nursing surveillance for control of hyperglycemia and hyperthermia has been shown to improve patient outcomes.

METHODS

We conducted an observational pilot study to assess compliance with American guidelines for glucose and temperature control and association with discharge outcomes in consecutive acute stroke patients admitted to 5 US comprehensive stroke centers. Data for the first 5 days of stroke admission were collected from electronic medical records and entered and analyzed in SPSS using descriptive statistics, Mann-Whitney U test, Student t tests, and logistic regression.

RESULTS

A total of 1669 consecutive glucose and 3782 consecutive temperature measurements were taken from a sample of 235 acute stroke patients; the sample was 87% ischemic and 13% intracerebral hemorrhage. Poor glucose control was found in 33% of patients, and the most frequent control method ordered (35%) was regular insulin sliding scale without basal dosing. Poor temperature control was noted in 10%, and 39% did not have temperature recorded in the emergency department. Lower admission National Institutes of Health Stroke Scale score and well-controlled glucose were independent predictors of favorable outcome (discharge modified Rankin Scale score, 0-2) in reperfusion patients.

CONCLUSION

Glucose and temperature control may be overlooked in this era of rapid stroke diagnosis and treatment. Acute stroke nurses are well positioned to assume leadership of glucose and temperature monitoring and treatment.

APX3330 Promotes Neurorestorative Effects after Stroke in Type One Diabetic Rats

APX3330 is a selective inhibitor of APE1/Ref-1 redox activity. In this study, we investigate the therapeutic effects and underlying mechanisms of APX3330 treatment in type one diabetes mellitus (T1DM) stroke rats. Adult male Wistar rats were induced with T1DM and subjected to transient middle cerebral artery occlusion (MCAo) and treated with either PBS or APX3330 (10mg/kg, oral gavage) starting at 24h after MCAo, and daily for 14 days. Rats were sacrificed at 14 days after MCAo and, blood brain barrier (BBB) permeability, ischemic lesion volume, immunohistochemistry, cell death assay, Western blot, real time PCR, and angiogenic ELISA array were performed. Compared to PBS treatment, APX3330 treatment of stroke in T1DM rats significantly improves neurological functional outcome, decreases lesion volume, and improves BBB integrity as well as decreases total vessel density and VEGF expression, while significantly increases arterial density in the ischemic border zone (IBZ). APX3330 significantly increases myelin density, oligodendrocyte number, oligodendrocyte progenitor cell number, synaptic protein expression, and induces M2 macrophage polarization in the IBZ of T1DM stroke rats. Compared to PBS treatment, APX3330 treatment significantly decreases plasminogen activator inhibitor type-1 (PAI-1), monocyte chemotactic protein-1 and matrix metalloproteinase 9 (MMP9) and receptor for advanced glycation endproducts expression in the ischemic brain of T1DM stroke rats. APX3330 treatment significantly decreases cell death and MMP9 and PAI-1 gene expression in cultured primary cortical neurons subjected to high glucose and oxygen glucose deprivation, compared to untreated control cells. APX3330 treatment increases M2 macrophage polarization and decreases inflammatory factor expression in the ischemic brain as well as promotes neuroprotective and neurorestorative effects after stroke in T1DM rats.

Impact of Metabolic Diseases on Cerebral Circulation: Structural and Functional Consequences

Metabolic diseases including obesity, insulin resistance, and diabetes have profound effects on cerebral circulation. These diseases not only affect the architecture of cerebral blood arteries causing adverse remodeling, pathological neovascularization, and vasoregression but also alter the physiology of blood vessels resulting in compromised myogenic reactivity, neurovascular uncoupling, and endothelial dysfunction. Coupled with the disruption of blood brain barrier (BBB) integrity, changes in blood flow and microbleeds into the brain rapidly occur. This overview is organized into sections describing cerebrovascular architecture, physiology, and BBB in these diseases. In each section, we review these properties starting with larger arteries moving into smaller vessels. Where information is available, we review in the order of obesity, insulin resistance, and diabetes. We also tried to include information on biological variables such as the sex of the animal models noted since most of the information summarized was obtained using male animals. © 2018 American Physiological Society. Compr Physiol 8:773-799, 2018.

Pivotal neuroinflammatory and therapeutic role of high mobility group box 1 in ischemic stroke

Stroke is a major cause of mortality and disability worldwide. Stroke is a frequent and severe neurovascular disorder. The main cause of stroke is atherosclerosis, and the most common risk factor for atherosclerosis is hypertension. Therefore, prevention and treatment of stroke are crucial issues in humans. High mobility group box 1 (HMGB1) is non-histone nuclear protein that is currently one of the crucial proinflammatory alarmins in ischemic stroke (IS). It is instantly released from necrotic cells in the ischemic core and activates an early inflammatory response. HMGB1 may signal via its putative receptors, such as receptor for advanced glycation end products (RAGE), toll-like receptors (TLRs) as well as matrix metalloproteinase (MMP) enzymes during IS. These receptors are expressed in brain cells. Additionally, brain-released HMGB1 can be redox modified in the circulation and activate peripheral immune cells. The role of HMGB1 may be more complex. HMGB1 possesses beneficial actions, such as endothelial activation, enhancement of neurite outgrowth, and neuronal survival. HMGB1 may also provide a novel link for brain-immune communication leading to post-stroke immunomodulation. Therefore, HMGB1 is new promising therapeutic intervention aimed at promoting neurovascular repair and remodeling after stroke. In this review, we look at the mechanisms of secretion of HMGB1, the role of receptors, MMP enzymes, hypoglycemia, atherosclerosis, edema, angiogenesis as well as neuroimmunological reactions and post-ischemic brain recovery in IS. We also outline therapeutic roles of HMGB1 in IS.

D-4F increases microRNA-124a and reduces neuroinflammation in diabetic stroke rats

D-4F is an apolipoprotein-A1 mimetic peptide that promotes anti-inflammatory effects. MicroRNA-124 is the most abundant brain-specific microRNA and has anti-inflammatory effects. In this study, we investigated the therapeutic efficacy and mechanisms of D-4F treatment of stroke in type one diabetes mellitus (T1DM) rats. Male Wistar rats were induced with T1DM, subjected to embolic middle cerebral artery occlusion and treated with PBS or D-4F (1 mg/kg i.p.) at 2, 24 and 48 hours after stroke (n=8/group). A battery of function tests, brain blood barrier (BBB) integrity, white matter changes and microRNA expression were evaluated in vivo and in vitro. D-4F treatment in T1DM-stroke rats significantly improves functional outcome, decreases BBB leakage, increases tight junction protein expression, decreases white matter damage and inflammatory factor expression, while increasing anti-inflammatory M2 macrophage polarization in the ischemic brain. D-4F significantly increases microRNA-124a expression, and decreases matrix metalloproteinase-9, tumor necrosis factor-α and toll-like receptor-4 gene expression in the ischemic brain, and in primary cortical neuronal and microglial cultures. Inhibition of microRNA-124 in cultured primary cortical neurons and microglia attenuates D-4F induced anti-inflammatory effects and M2 macrophage polarization. D-4F treatment of T1DM-stroke increases microRNA-124 expression, promotes anti-inflammatory effects and M2 macrophage polarization, which may contribute to D-4F-induced improvement in neurological function, and BBB and white matter integrity.

Diabetes aggravates decreases in hippocalcin and parvalbumin expression in focal cerebral ischemia

Hyperglycemia is a major risk factor for stroke and increases brain damage during ischemic stroke. Hyperglycemia increases the intracellular calcium concentration after ischemic injury, thereby triggering neuronal cell death. Calcium binding proteins, including hippocalcin and parvalbumin, are critical regulators of intracellular calcium levels. This study aimed to investigate whether hyperglycemic conditions affect hippocalcin and parvalbumin expression during ischemic brain injury. Male adult rats were treated intraperitoneally with streptozotocin (40mg/kg) to induce hyperglycemia. Four weeks later, cerebral ischemic injury was induced via surgical middle cerebral artery occlusion (MCAO). Cerebral cortex samples were collected 24h after MCAO. A proteomic approach showed that the protein levels of hippocalcin and parvalbumin were significantly decreased in streptozotocin-treated animals with MCAO injury compared to streptozotocin-treated animals and animals that underwent MCAO alone. Reverse transcription-PCR and Western blot analyses clearly confirmed the decreased levels of these proteins. These decreases indicate dysregulation of the intracellular calcium balance and induction of cell death. Thus, these results suggest that significantly decreased levels of hippocalcin and parvalbumin exacerbate neuronal cell death in diabetic animals with ischemic brain injury.

Neuroprotective effect of salvianolate lyophilized injection against cerebral ischemia in type 1 diabetic rats

BACKGROUND

Salvianolate lyophilized injection (SLI) has been clinically used in China for the treatment of acutely cerebral infarction. Clinical and experimental studies have shown that Diabetes mellitus (DM) not only increases the risk of ischemic stroke recurrence but also leads to poor outcomes and increases fatality rates after stroke. Our previous study has proved that SLI can reduce the infarct volume after stroke in type 1 diabetic rats. The aim of the study is to explore the mechanism of SLI on stroke outcome in type 1 diabetic (T1DM) rats.

METHODS

Type 1 diabetes rats model (T1DM) was induced in male Wistar rats by intraperitoneal (i.p) injection of streptozotocin (60 mg/kg) and T1DM rats were subjected to intraluminal middle cerebral artery occlusion (MCAO). The T1DM + MCAO rats were randomly divided into six groups: sham-operated, model-vehicle, positive control group (Edaravone-treating, DE 6 mg/kg) and SLI-treating group (10.5 mg/kg, 21 mg/kg and 42 mg/kg). SLI and DE were administered by tail vein injection at 3 h after MCAO, then daily for 14 days. Micro-CT scans of the brain tissue revealed vessel characteristics and distribution in the ischemia zone. Glucose uptake was analyzed by PET/CT. RAGE, MMP9 and inflammatory factors (COX-2, TNF-α and ICAM-1), HQ-1, HQO-1 and Nrf-2 expression levels in the ischemic brain tissue were analyzed by Immunofluorescence staining and Western blot at 14 days after MCAO.

RESULTS

In this study, we have demonstrated that SLI treatment significantly increased the number of brain microvasculature in ipsilateral and glucose uptake in cortex, hippocampus and penumbra in the T1DM + MCAO rats. SLI also significantly decreased the expression of RAGE, MMP9 and inflammatory factors expression, and increased the expression of HQ-1, HQO-1 and Nrf-2 in T1DM + MCAO rats.

CONCLUSION

The study showed that SLI could protect against cerebral ischemia injury in T1DM + MCAO rats and the mechanism is related to decrease inflammatory factors and activate of the Nrf2/HO-1 signaling pathway.

Inhibiting HMGB1 Reduces Cerebral Ischemia Reperfusion Injury in Diabetic Mice

High mobility group box1 (HMGB1) promotes inflammatory injury, and accumulating evidence suggests that it plays a key role in brain ischemia reperfusion (I/R), as well as the development of diabetes mellitus (DM). The purpose of this study was to investigate whether HMGB1 plays a role in brain I/R in a DM mouse model. Diabetes mellitus was induced by a high-calorie diet and streptozotocin treatment, and cerebral ischemia was induced by middle cerebral artery occlusion. We examined HMGB1 levels following cerebral I/R injury in DM and non-DM mice and evaluated the influence of altered HMGB1 levels on the severity of cerebral injury. Serum HMGB1 levels and the inflammatory factors IL-1β, IL-6, and inflammation-related enzyme iNOS were significantly elevated in DM mice with brain I/R compared with non-DM mice with brain I/R. Blocking HMGB1 function by intraperitoneal injection of anti-HMGB1 neutralizing antibodies reversed the inflammatory response and the extent of brain damage, suggesting that HMGB1 plays an important role in cerebral ischemic stroke in diabetic mice.

Diabetes Worsens Functional Outcomes in Young Female Rats: Comparison of Stroke Models, Tissue Plasminogen Activator Effects, and Sexes

Diabetes worsens stroke outcome and increases the risk of hemorrhagic transformation (HT) after ischemic stroke, especially with tissue plasminogen activator (tPA) treatment. The widespread use of tPA is still limited by the fear of hemorrhagic transformation (HT), and underlying mechanisms are actively being pursued in preclinical studies. However, experimental models use a 10 times higher dose of tPA than the clinical dose (10 mg/kg) and mostly employ only male animals. In this translational study, we hypothesized that low-dose tPA will improve the functional recovery after the embolic stroke in both control and diabetic male and female animals. Diabetes was induced in age-matched male and female Wistar rats with high fat diet and low-dose streptozotocin (30 mg/kg, i.p.). Embolic stroke was induced with clot occlusion of the middle cerebral artery (MCA). The animals were treated with or without tPA (1 mg/kg, i.v.) at 90 min after surgery. An additional set of animals were subjected to 90 min MCAO with suture. Neurological deficits (composite score and adhesive removal test-ART), infarct size, edema ratio, and HT index were assessed 3 days after surgery. In the control groups, female rats had smaller infarcts and better functional outcomes. tPA decreased infarct size in both sexes with a greater effect in males. While there was no difference in HT between males and females without tPA, HT was less in the female + tPA group. In the diabetic groups, neuronal injury increased in females reaching that of the infarct sizes seen in male rats. tPA decreased infarct size in females but not males. HT was greater in female rats than in males and was not further increased with tPA. Diabetes worsened neurological deficits in both sexes. Male animals showed improved sensorimotor skills, especially with tPA treatment, but there was no improvement in females. These data suggest that diabetes amplifies neurovascular injury and neurological deficits in both sexes. Human dose tPA offers some degree of protection in male but not female rats. Given that control female animals experience less injury compared to male rats, the diabetes effect is more profound in females.

Hyperglycemia aggravates decreases of PEA-15 and its two phosphorylated forms in cerebral ischemia

Diabetes is a metabolic health disorder and an important risk factor for stroke. Phosphoprotein enriched in astrocytes 15 (PEA-15) is a multifunctional protein modulating cell proliferation, survival, apoptosis and glucose metabolism. This study investigated whether diabetes modulates the expression of PEA-15 and two phosphorylated forms (Ser 104 and Ser 116) in middle cerebral artery occlusion (MCAO)-induced brain injury. Male Sprague-Dawley rats were administrated with streptozotocin (40 mg/kg) and were underwent right middle cerebral artery occlusion (MCAO) 4 weeks after streptozotocin injection. Brain tissues were collected 24 hr after MCAO and stained using triphenyltetrazolium chloride. Western blot analysis was performed to elucidate the expression of PEA-15 and two phosphorylated forms (Ser 104 and Ser 116) in right cerebral cortex. Infarct volume during MCAO injury was severely increased in diabetic animals compared to non-diabetic animals. We identified the decrease in PEA-15 in animals that underwent MCAO using proteomic approach. PEA-15 expression during MCAO was strongly decreased in diabetic animals compared to non-diabetic animals. Western blots analysis confirmed that diabetes exacerbated the decrease in PEA-15 expression after MCAO. Moreover, decrease in expression of phospho-PEA-15 (Ser 104 and Ser 116) was greater in diabetic than in non-diabetic animals. These results suggested that a diabetic condition may aggravate brain damage through decreasing expression of PEA-15 and phospho-PEA-15 (Ser 104 and Ser 116) in ischemic brain injury.

Cerebral ischemic damage in diabetes: an inflammatory perspective

Stroke is one of the leading causes of death worldwide. A strong inflammatory response characterized by activation and release of cytokines, chemokines, adhesion molecules, and proteolytic enzymes contributes to brain damage following stroke. Stroke outcomes are worse among diabetics, resulting in increased mortality and disabilities. Diabetes involves chronic inflammation manifested by reactive oxygen species generation, expression of proinflammatory cytokines, and activation/expression of other inflammatory mediators. It appears that increased proinflammatory processes due to diabetes are further accelerated after cerebral ischemia, leading to increased ischemic damage. Hypoglycemia is an intrinsic side effect owing to glucose-lowering therapy in diabetics, and is known to induce proinflammatory changes as well as exacerbate cerebral damage in experimental stroke. Here, we present a review of available literature on the contribution of neuroinflammation to increased cerebral ischemic damage in diabetics. We also describe the role of hypoglycemia in neuroinflammation and cerebral ischemic damage in diabetics. Understanding the role of neuroinflammatory mechanisms in worsening stroke outcome in diabetics may help limit ischemic brain injury and improve clinical outcomes.

MiR-126 Contributes to Human Umbilical Cord Blood Cell-Induced Neurorestorative Effects After Stroke in Type-2 Diabetic Mice

Diabetes mellitus (DM) is a high risk factor for stroke and leads to more severe vascular and white-matter injury than stroke in non-DM. We tested the neurorestorative effects of delayed human umbilical cord blood cell (HUCBC) treatment of stroke in type-2 diabetes (T2DM). db/db-T2DM and db/+-non-DM mice were subjected to distal middle cerebral artery occlusion (dMCAo) and were treated 3 days after dMCAo with: (a) non-DM + Phosphate buffered saline (PBS); (b) T2DM + PBS; (c) T2DM + naïve-HUCBC; (d) T2DM + miR-126(-/-) HUCBC. Functional evaluation, vascular and white-matter changes, neuroinflammation, and miR-126 effects were measured in vivo and in vitro. T2DM mice exhibited significantly decreased serum and brain tissue miR-126 expression compared with non-DM mice. T2DM + HUCBC mice exhibited increased miR-126 expression, increased tight junction protein expression, axon/myelin, vascular density, and M2-macrophage polarization. However, decreased blood-brain barrier leakage, brain hemorrhage, and miR-126 targeted gene vascular cell adhesion molecule-1 and monocyte chemotactic protein 1 expression in the ischemic brain as well as improved functional outcome were present in HUCBC-treated T2DM mice compared with control T2DM mice. MiR-126(-/-) HUCBC-treatment abolished the benefits of naïve-HUCBC-treatment in T2DM stroke mice. In vitro, knock-in of miR-126 in primary cultured brain endothelial cells (BECs) or treatment of BECs with naïve-HUCBCs significantly increased capillary-like tube formation, and increased axonal outgrowth in primary cultured cortical neurons; whereas treatment of BECs or cortical neurons with miR-126(-/-) HUCBC attenuated HUCBC-treatment-induced capillary tube formation and axonal outgrowth. Our data suggest delayed HUCBC-treatment of stroke increases vascular/white-matter remodeling and anti-inflammatory effects; MiR-126 may contribute to HUCBC-induced neurorestorative effects in T2DM mice.

Reduced HMGB 1-Mediated Pathway and Oxidative Stress in Resveratrol-Treated Diabetic Mice: A Possible Mechanism of Cardioprotection of Resveratrol in Diabetes Mellitus

Myocardial fibrosis and inflammation are intricately linked in diabetic cardiomyopathy (DCM), and resveratrol has been shown to attenuate oxidative stress, inflammation, and fibrosis in several cell types or animal models. High mobility group box 1 (HMGB 1), a proinflammatory cytokine, has been reported to regulate fibrosis and inflammation in various organs. Then the present study aimed to reveal the expression of HMGB 1-mediated signaling pathway and oxidative stress in resveratrol-treated diabetic mice. The significant increase in serum HMGB 1 concentration in diabetic mice was attenuated by treatment with resveratrol. Similarly, western blot analysis revealed a significant increase of HMGB 1 protein in monocytes and heart tissues of diabetic mice, and resveratrol partly normalized the changes. In addition, resveratrol abrogated the increased expression of HMGB 1-mediated signaling pathway, oxidative stress, fibrosis, and inflammation in diabetic hearts. In conclusion, inhibition of HMGB 1-mediated signaling pathway and oxidative stress may contribute to resveratrol-induced anti-inflammatory and antifibrotic effects in DCM.

Is shorter transient middle cerebral artery occlusion (t-MCAO) duration better in stroke experiments on diabetic female Sprague Dawely rats?

AIM

To determine optimal duration of transient middle cerebral artery occlusion (t-MCAO) for a stroke model in female diabetic Sprague-Dawley (SD) rats.

METHODS

Streptozotocin-induced type-1 diabetic SD female rats (n = 25, 12 weeks old, five groups; n = 5 per group) were subjected to different duration of t-MCAO (20, 30, 45, 60 and 90 minutes) followed by reperfusion. A control group of rats without diabetes (n = 5) was subjected to 30 minutes of t-MCAO followed by reperfusion. Twenty-four hours after reperfusion, infarct volumes were evaluated by 2,3,5-triphenyltetrazolium chloride (TTC) staining.

RESULTS

Intra-ischaemic reductions of regional cerebral blood flow (rCBF) were similar in all groups (68-75% of baseline values). Reperfusion was significantly impaired in the 90-minute ischaemia group (56-62% vs 80-125% in other groups). Twenty minutes of t-MCAO induced a small infarct (3 ± 5% of ischaemic hemisphere). Thirty minutes of ischaemia produced a significantly larger infarct (46 ± 6%). In the 45 and 60 minute groups, ischaemia infarct was 52 ± 5% and 59 ± 3% of the ischaemic hemisphere, respectively. Ischaemia of 90' led to a massive stroke (89 ± 6% of ischaemic hemisphere encompassing the whole striatum (22 ± 3%) and almost the whole MCA irrigated cortex area (67 ± 6%)). Thirty minutes of t-MCAO did not produce stroke in the control group.

CONCLUSION

The diabetic rat stroke model should be different from the non-diabetic, because female type-1 diabetic SD rats are highly sensitive to brain ischaemia and it is necessary to significantly shorten the duration of t-MCAO, optimally to 30 minutes.

miR-145 Regulates Diabetes-Bone Marrow Stromal Cell-Induced Neurorestorative Effects in Diabetes Stroke Rats

In rats with type 1 diabetes mellitus (T1DM) subject to stroke, the therapeutic effects and underlying mechanisms of action of bone-marrow stromal cells (BMSCs) derived from T1DM rats (DM-BMSCs) and BMSCs derived from normal rats (Nor-BMSCs) were compared. In vitro and in vivo, DM-BMSCs exhibited decreased miR-145 expression. In T1DM rats, DM-BMSC treatment significantly improved functional outcome and increased vascular and white matter remodeling. However, overexpression of miR-145 in DM-BMSCs attenuates DM-BMSC-induced neurorestorative effects in T1DM stroke rats.

In rats with type 1 diabetes (T1DM), the therapeutic effects and underlying mechanisms of action of stroke treatment were compared between bone-marrow stromal cells (BMSCs) derived from T1DM rats (DM-BMSCs) and BMSCs derived from normal rats (Nor-BMSCs). The novel role of microRNA-145 (miR-145) in mediating DM-BMSC treatment-induced benefits was also investigated. T1DM rats (n = 8 per group) underwent 2 hours of middle cerebral artery occlusion (MCAo) and were treated 24 hours later with the one of the following (5 × 10⁶ cells administered i.v.): (a) phosphate-buffered saline (PBS); (b) Nor-BMSCs; (c) DM-BMSCs; (d) DM-BMSCs with miR-145 overexpression (miR-145+/+DM-BMSCs); or (e) Nor-BMSCs with miR-145 knockdown. Evaluation of functional outcome, vascular and white-matter remodeling and microRNA expression was made, and in vitro studies were performed. In vitro, DM-BMSCs exhibited decreased miR-145 expression and increased survival compared with Nor-BMSCs. Capillary tube formation and axonal outgrowth in cultured primary cortical neurons were significantly increased by DM-BMSC-conditioned medium compared with Nor-BMSCs, and significantly decreased by miR-145+/+DM-BMSC-conditioned medium compared with DM-BMSCs. In T1DM rats in which stroke had been induced (T1DM stroke rats), DM-BMSC treatment significantly improved functional outcome, increased vascular and white matter remodeling, decreased serum miR-145 expression, and increased expression of the miR-145 target genes adenosine triphosphate-binding cassette transporter 1 (ABCA1) and insulin-like growth factor 1 receptor (IGFR1), compared with Nor-BMSCs or PBS treatment. However, miR-145+/+DM-BMSCs significantly increased serum miR-145 expression and decreased brain ABCA1 and IGFR1 expression, as well as attenuated DM-BMSC-induced neurorestorative effects in T1DM-MCAo rats. DM-BMSCs exhibited decreased miR-145 expression. In T1DM-MCAo rats, DM-BMSC treatment improved functional outcome and promoted neurorestorative effects. The miR-145/ABCA1/IGFR1 pathway may contribute to the enhanced DM-BMSCs’ functional and neurorestorative effects in T1DM stroke rats.

Significance

In rats with type 1 diabetes (T1DM), the therapeutic effects and underlying mechanisms of action of stroke treatment were compared between bone-marrow stromal cells (BMSCs) derived from T1DM rats (DM-BMSCs) and BMSCs derived from normal rats (Nor-BMSCs). In vitro, DM-BMSCs and derived exosomes decreased miR-145 expression and increased DM-BMSC survival, capillary tube formation, and axonal outgrowth, compared with Nor-BMSCs; these effects were decreased by DM-BMSCs in which miR-145 was overexpressed. In vivo, compared with Nor-BMSC or phosphate-buffered saline treatment, DM-BMSC treatment improved functional outcome and vascular and white matter remodeling, decreased serum miR-145 expression, and increased expression of the miR-145 target genes ABCA1 and IGFR1. microRNA-145 mediated the benefits induced by DM-BMSC treatment.

Inhibition of CaMKIV relieves streptozotocin-induced diabetic neuropathic pain through regulation of HMGB1

Background

The pathogenesis of diabetic neuropathic pain is complicated and its underlying mechanisms remain unclear. Calmodulin-dependent protein kinases (CaMKs) IV (CaMKIV), one of CaMKs, regulates several transcription factors in pain mechanisms. High-mobility group box 1 (HMGB1) is a key mediator in diabetic neuropathic pain. This study aims to find the roles and mechanisms of CaMIV in diabetic neuropathic pain.

Methods

Diabetic animal models were constructed by injecting with streptozotocin (STZ) intraperitoneally. They were randomly divided into seven groups (n = 6 per group): Naive, Normal Saline, STZ, STZ + Sham, STZ + DMSO and STZ + KN93 (an inhibitor of CaMKIV) (50 μg), STZ + KN93 (100 μg), which received KN93 (50 or 100 μg) intrathecally after the administration of STZ. Phospho-CaMKIV (pCaMKIV) and HMGB1 expression in rat dorsal root ganglion (DRG) and RAW264.7 cell line were measured by western blot. Distribution of pCaMKIV immune reactivity in different subpopulations of DRG neurons was measured by double-immunofluorescence staining.

Results

The pCaMKIV and HMGB1 in DRG significantly increased after STZ administration, and pCaMKIV can regulate the expression of HMGB1 based on both cellular and animal models. Pretreatment with CaMKIV inhibitor attenuated STZ-induced mechanical allodynia and thermal hyperalgesia, as well as reduced HMGB1 expression in the DRG.

Conclusions

This study demonstrates that CaMKIV can relieve STZ-induced diabetic neuropathic pain. The mechanism of this function depended on the process: pCaMKIV localized in the nuclei of DRG neurons and regulated HMGB1 which was an important mediator of neuropathic pain. These findings reported CaMKIV may be a potential target or important node in relieving diabetic neuropathic pain.

Therapy Effects of Bone Marrow Stromal Cells on Ischemic Stroke

Stroke is the second most common cause of death and major cause of disability worldwide. Recently, bone marrow stromal cells (BMSCs) have been shown to improve functional outcome after stroke. In this review, we will focus on the protective effects of BMSCs on ischemic brain and the relative molecular mechanisms underlying the protective effects of BMSCs on stroke.

Bone marrow stromal cells inhibits HMGB1-mediated inflammation after stroke in type 2 diabetic rats

High-mobility group box 1 (HMGB1), a ligand of receptor for advanced glycation endproducts (RAGE), functions as a proinflammatory factor. It is mainly involved in inflammatory activation and contributes to the initiation and progression of stroke. By using a model of transient middle cerebral artery occlusion (MCAo) in type 2 diabetic rats, we investigated the changes of pro-inflammation mediators, blood-brain barrier (BBB) leakage and functional outcome after stroke. Type 2 diabetic rats did not show an increased lesion volume, but exhibited significantly increased expression of HMGB1 and RAGE, BBB leakage, as well as decreased functional outcome after stroke compared with control rats. Injection of bone marrow stromal cells (BMSCs) into type 2 diabetic rats significantly reduced the expression of HMGB1 and RAGE, attenuated BBB leakage, and improved functional outcome after stroke. BMSCs-treated type 2 diabetic rats inhibited inflammation and improved functional outcome after stroke. Furthermore, in vitro data support the hypothesis that BMSCs-induced reduction of HMGB1 and RAGE in T2DM-MCAo rats contributed to attenuated inflammatory response in the ischemic brain, which may lead to the beneficial effects of BMSCs treatment. Further investigation of BMSCs treatment in type 2 diabetic stroke is warranted.

Experimental animal models and inflammatory cellular changes in cerebral ischemic and hemorrhagic stroke

Stroke, including cerebral ischemia, intracerebral hemorrhage, and subarachnoid hemorrhage, is the leading cause of long-term disability and death worldwide. Animal models have greatly contributed to our understanding of the risk factors and the pathophysiology of stroke, as well as the development of therapeutic strategies for its treatment. Further development and investigation of experimental models, however, are needed to elucidate the pathogenesis of stroke and to enhance and expand novel therapeutic targets. In this article, we provide an overview of the characteristics of commonly-used animal models of stroke and focus on the inflammatory responses to cerebral stroke, which may provide insights into a framework for developing effective therapies for stroke in humans.

D-4F Decreases White Matter Damage After Stroke in Mice

BACKGROUND AND PURPOSE

Stroke-induced neuroinflammation and white matter damage are associated with neurological deficits. Whether D-4F, an apolipoprotein A-I mimetic peptide, treatment of stroke decreases neuroinflammation and white matter damage and improves functional outcome has not been investigated.

METHODS

Adult male C57BL/6 mice were subjected to permanent middle cerebral artery occlusion (MCAo) and were orally administered saline as a vehicle control and different doses of D-4F (2, 4, 8, 16, or 32 mg/kg) starting at 2 h after MCAo and daily until euthanized at 7 days after MCAo. D-4F treatment did not alter the blood levels of high-density lipoprotein, total cholesterol, triglyceride, blood-brain barrier leakage, and infarction volume compared with control group.

RESULTS

D-4F (16 mg/kg) treatment of stroke significantly improved functional outcome, increased the white matter density and the number of oligodendrocyte progenitor cells in the ischemic boundary zone of the ipsilateral striatum, and increased myelin basic protein, insulin-like growth factor-1 (IGF1), but decreased inflammatory factor Toll-like receptor-4 and tumor necrosis factor-α expression in the ischemic brain 7 days after MCAo (P<0.05, n=11/group). The neurite/axonal outgrowth in primary cultured neurons was significantly increased when treated with D-4F (100 ng/mL) and IGF1 (100 ng/mL) compared with the nontreatment control. Inhibition of IGF1 significantly attenuated D-4F or IGF1 treatment-induced axonal outgrowth. D-4F-treatment did not increase oligodendrocyte-progenitor cell proliferation but decreased oligodendrocyte-progenitor cell death.

CONCLUSIONS

D-4F treatment initiated 2 h after MCAo decreases neuroinflammation and white matter damage and improves functional outcome after stroke. D-4F-induced increase in IGF1 may contribute to D-4F-induced neurite/axonal outgrowth after stroke.

Intranasal administration of human umbilical cord mesenchymal stem cells-conditioned medium enhances vascular remodeling after stroke

Stem cell-based treatments have been reported to be a potential strategy for stroke. However, tumorigenic potential and low survival rates of transplanted cells could attenuate the efficacy of the stem cell-based treatments. The application of stem cell-condition medium (CM) may be a practicable approach to conquer these limitations. In this study, we investigated whether intranasal administration of human umbilical cord mesenchymal stem cells (hUCMSCs)-CM has the therapeutic effects in rats after stroke. Adult male rats were subjected to middle cerebral artery occlusion (MCAo) and were treated by intranasal routine with or without hUCMSCs-CM (1 ml/kg/d), starting 24h after MCAo and daily for 14 days. Neurological functional tests, blood brain barrier (BBB) leakage, were measured. Angiogenesis and angiogenic factor expression were measured by immunohistochemistry, and Western blot, respectively. hUCMSCs-CM treatment of stroke by intranasal routine starting 24h after MCAo in rats significantly enhances BBB functional integrity and promotes functional outcome but does not decrease lesion volume compared to rats in DMEM/F12 medium control group and saline control group. Treatment of ischemic rats with hUCMSCs-CM by intranasal routine also significantly decreases the levels of Ang2 and increases the levels of both Ang1 and Tie2 in the ischemic brain. To take together, increased expression of Ang1 and Tie2 and decreased expression of Ang2, induced by hUCMSCs-CM treatment, contribute to vascular remodeling in the ischemic brain which plays an important role in functional outcome after stroke.

Neurorestorative Therapy of Stroke in Type 2 Diabetes Mellitus Rats Treated With Human Umbilical Cord Blood Cells

BACKGROUND AND PURPOSE

Diabetes mellitus is a high-risk factor for ischemic stroke. Diabetic stroke patients suffer worse outcomes, poor long-term recovery, risk of recurrent strokes, and extensive vascular damage. We investigated the neurorestorative effects and the underlying mechanisms of stroke treatment with human umbilical cord blood cells (HUCBCs) in type 2 diabetes mellitus (T2DM) rats.

METHODS

Adult male T2DM rats were subjected to 2 hours of middle cerebral artery occlusion (MCAo). Three days after MCAo, rats were treated via tail-vein injection with (1) PBS and (2) HUCBCs (5×10(6)), n=10 per group.

RESULTS

HUCBC stroke treatment initiated 3 days after MCAo in T2DM rats did not significantly decrease blood-brain barrier leakage (P=0.1) and lesion volume (P=0.078), but significantly improved long-term functional outcome and decreased brain hemorrhage (P<0.05) when compared with the PBS-treated T2DM MCAo control group. HUCBC treatment significantly promoted white matter remodeling as indicated by increased expression of Bielschowsky silver (axons marker), Luxol fast blue (myelin marker), SMI-31 (neurofilament), and Synaptophysin in the ischemic border zone. HUCBC promoted vascular remodeling and significantly increased arterial and vascular density. HUCBC treatment of stroke in T2DM rats significantly increased M2 macrophage polarization (increased M2 macrophage, CD163and CD 206; decreased M1 macrophage, ED1 and inducible nitric oxide synthase expression) in the ischemic brain compared with PBS-treated T2DM MCAo controls (P<0.05). HUCBC also significantly decreased proinflammatory factors, that is, matrix metalloproteinase 9, receptor for advanced glycation end products and toll-like receptor 4 expression in the ischemic brain.

CONCLUSIONS

HUCBC treatment initiated 3 days after stroke significantly increased white matter and vascular remodeling in the ischemic brain as well as decreased neuroinflammatory factor expression in the ischemic brain in T2DM rats and promoted M2 macrophage polarization. HUCBC reduction of neuroinflammation and increased vascular and white matter axonal remodeling may contribute to the HUCBC-induced beneficial effects in T2DM stroke rats.

HMGB1 in health and disease

Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.

Oxygen-glucose deprivation of neurons transfected with toll-like receptor 3-siRNA: Determination of an optimal transfection sequence

Toll-like receptor 3 protein expression has been shown to be upregulated during cerebral ischemia/reperfusion injury in rats. In this study, rat primary cortical neurons were subjected to oxygen-glucose deprivation to simulate cerebral ischemia/reperfusion injury. Chemically synthesized small interfering RNA (siRNA)-1280, -1724 and -418 specific to toll-like receptor 3 were transfected into oxygen-glucose deprived cortical neurons to suppress the upregulation of toll-like receptor 3 protein expression. Western blotting demonstrated that after transfection with siRNA, toll-like receptor 3 protein expression reduced, especially in the toll-like receptor 3-1724 group. These results suggested that siRNA-1724 is an optimal sequence for inhibiting toll-like receptor 3 expression in cortical neurons following oxygen-glucose deprivation.

HUCBCs increase angiopoietin 1 and induce neurorestorative effects after stroke in T1DM rats

BACKGROUND AND PURPOSE

We investigated the neurorestorative effects and underlying mechanisms of stroke treatment with human umbilical cord blood cells (HUCBCs) in Type one diabetes mellitus (T1DM) rats.

METHODS

Type one diabetes mellitus rats were subjected to middle cerebral artery occlusion (MCAo) and 24 h later were treated with: (1) phosphate-buffered-saline; (2) HUCBCs. Brain endothelial cells (MBECs) were cultured and capillary tube formation was measured.

RESULTS

Human umbilical cord blood cells treatment significantly improved functional outcome and promoted white matter (WM) remodeling, as identified by Bielschowsky silver, Luxol fast blue and SMI-31 expression, increased oligodendrocyte progenitor cell and oligodendrocyte density after stroke in T1DM rats. HUCBC also promoted vascular remodeling, evident from enhanced vascular and arterial density and increased artery diameter, and decreased blood-brain barrier leakage. HUCBC treatment also increased Angiopoietin-1 and decreased receptor for advanced glycation end-products (RAGE) expression compared to T1DM-MCAo control. In vitro analysis of MBECs demonstrated that Ang1 inversely regulated RAGE expression. HUCBC and Ang1 significantly increased capillary tube formation and decreased inflammatory factor expression, while anti-Ang1 attenuated HUCBC-induced tube formation and antiinflammatory effects.

CONCLUSION

Human umbilical cord blood cells is an effective neurorestorative therapy in T1DM-MCAo rats and the enhanced vascular and WM remodeling and associated functional recovery after stroke may be attributed to increasing Angiopoietin-1 and decreasing RAGE.

8-O-acetyl shanzhiside methylester attenuates cerebral ischaemia/reperfusion injury through an anti-inflammatory mechanism in diabetic rats

Inflammatory activation plays a vital role in the pathophysiological mechanisms of stroke and diabetes mellitus (DM), exerts the deleterious effects on the progression of the brain and leads to vascular damage in diabetic stroke. The objectives of this study were to investigate the effects of 8-O-acetyl shanzhiside methylester (ND01) on tumour necrosis factor-α (TNF-α)-stimulated SH-SY5Y cell line in vitro and the experimental ischaemic diabetic stroke model in vivo. TNF-α-stimulated SH-SY5Y cells were pre-incubated with ND01, then analysed protein expression. For in vivo experiment, the diabetic rats were subjected to middle cerebral artery occlusion (MCAO) for 30 min. followed by reperfusion for 23 hr. Treatment of SH-SY5Y cells with ND01 blocked TNF-α-induced nuclear transcription factor κB (NF-κB) activation and decreased high-mobility group box-1 (HMGB-1) expression. ND01 40 mg/kg demonstrated significant neuroprotective effect even after delayed administration at 4 hr after I/R. ND01 40 mg/kg attenuated the histopathological damage, decreased brain swelling, inhibited NF-κB activation and reduced HMGB-1 expression in ischaemic brain tissue. These data show that ND01 protects diabetic brain against I/R injury with a favourable therapeutic time-window by alleviating diabetic cerebral I/R injury and attenuating blood-brain barrier (BBB) breakdown, and its protective effects may involve HMGB-1 and NF-κB signalling pathway.

Inhibition of high-mobility group box 1 improves myocardial fibrosis and dysfunction in diabetic cardiomyopathy

BACKGROUND

High-mobility group box 1 (HMGB1) is an important mediator of the inflammatory response. Its expression is increased in diabetic cardiomyopathy (DCM), but its role is unclear. We investigated the potential role and mechanism of HMGB1 in diabetes-induced myocardial fibrosis and dysfunction in mice.

METHODS

In vivo, type 1 diabetes was induced by streptozotocin (STZ) in mice. HMGB1 expression was knocked down by lentivirus-mediated short-hairpin RNA (shRNA). Cardiac function was assessed by echocardiography. Total collagen deposition was assessed by Masson's trichrome and Picrosirius red staining. HMGB1, collagen I and III, and transforming growth factor β1 (TGF-β1) expression was quantified by immunostaining and western bolt analysis. In vitro, isolated neonatal cardiac fibroblasts were treated with high glucose (HG) or recombinant HMGB1 (rHMGB1). Pharmacologic (neutralizing anti-HMGB1 antibody) or genetic (shRNA-HMGB1) inhibition of HMGB1 was used to investigate the role of HMGB1 in HG-induced functional changes of cardiac fibroblasts.

RESULTS

In vivo, HMGB1 was diffusely expressed in the myocardium of diabetic mice. HMGB1 silencing ameliorated left ventricular dysfunction and remodeling and decreased collagen deposition in diabetic mice. In vitro, HG induced HMGB1 translocation and secretion in both viable cardiomyocytes and fibroblasts. Administration of rHMGB1 dose-dependently increased the expression of collagens I and III and TGF-β1 in cardiac fibroblasts. HMGB1 inhibition reduced HG-induced collagen production, matrix metalloproteinase (MMP) activities, proliferation, and activated mitogen-activated protein kinase signaling in cardiac fibroblasts.

CONCLUSIONS

HMGB1 inhibition could alleviate cardiac fibrosis and remodeling in diabetic cardiomyopathy. Inhibition of HMGB1 might have therapeutic potential in the treatment of the disease.

Neamine induces neuroprotection after acute ischemic stroke in type one diabetic rats

INTRODUCTION

Angiogenin is a member of the ribonuclease superfamily and promotes degradation of the basement membrane and the extracellular matrix. After stroke in type one diabetes (T1DM) rats, Angiogenin is significantly increased and the Angiogenin is inversely correlated with functional outcome. Neamine, an aminoglycoside antibiotic, blocks nuclear translocation of Angiogenin, thereby abolishing the biological activity of Angiogenin. In this study, we therefore investigated the effect and underlying protective mechanisms of Neamine treatment of stroke in T1DM.

METHODS

T1DM was induced in male Wistar rats by streptozotocin (60mg/kg, ip), and T1DM rats were subjected to embolic middle cerebral artery occlusion (MCAo). Neamine (10mg/kg ip) was administered at 2, 24 and 48h after the induction of embolic MCAo. A battery of functional outcome tests was performed. Blood-brain barrier (BBB) leakage, and lesion volume were evaluated and immunostaining, and Western blot were performed.

RESULTS

Neamine treatment of stroke in T1DM rats significantly decreased BBB leakage and lesion volume as well as improved functional outcome compared to T1DM-control. Neamine also significantly decreased apoptosis and cleaved caspase-3 in the ischemic brain. Using immunostaining, we found that Neamine treatment significantly decreased nuclear Angiogenin, nuclear factor kappa-light-chain-enhancer of activated B cells (NFκB) activity, advanced glycation endproducts receptor (RAGE) number, the positive area of toll-like receptor 4 (TLR4) and increased Angeopoietin-1 expression compared to T1DM-MCAo control rats. Western blot results are consistent with the immunostaining.

CONCLUSION

Neamine treatment of stroke is neuroprotective in T1DM rats. Inhibition of neuroinflammatory factor expression and decrease of BBB leakage may contribute to Neamine-induced neuroprotective effects after stroke in T1DM rats.

Niaspan attenuates the adverse effects of bone marrow stromal cell treatment of stroke in type one diabetic rats

AIMS

Our previous studies have found that bone-marrow-stromal cells (BMSC) therapy improves functional recovery after stroke in non-diabetic rats while increases brain hemorrhage and induces arteriosclerosis-like changes in type-one-diabetic (T1DM) rats. Niaspan treatment of stroke increases vascular stabilization, decreases brain hemorrhage and blood-brain-barrier (BBB) leakage in T1DM rats. We therefore tested the hypothesis that combination therapy of BMSC with Niaspan attenuates the side effects of BMSC monotherapy in T1DM rats.

METHODS

T1DM-rats induced by streptozotocin were subjected to 2 hours of middle-cerebral-artery occlusion (MCAo) and treated with: 1) PBS; 2) BMSC (5×10(6)); 3) Niaspan (40 mg/kg) daily for 14 days; 4) BMSC (5×10(6)) +Niaspan (40 mg/kg, daily for 14 days) combination starting at 24 hours after MCAo. All rats were monitored for 14 days.

RESULTS

Combination BMSC+Niaspan treatment of T1DM-MCAo rats did not increase brain hemorrhage, and significantly decreased BBB leakage and vascular arteriosclerosis-like changes as well as decreased Angiogenin, matrix metalloproteinase 9 (MMP9) and ED1 expression in ischemic brain and internal-carotid-artery compared to non-treatment control and BMSC monotherapy animals.

CONCLUSIONS

Combination therapy using BMSC with Niaspan decreases BBB leakage and cerebral arteriosclerosis-like changes. These beneficial effects may be attributed to the decreased expression of Angiogenin, MMP9 and ED1.

Combination BMSC and Niaspan treatment of stroke enhances white matter remodeling and synaptic protein expression in diabetic rats

Objective

White matter remodeling plays an important role in neurological recovery after stroke. Bone marrow stromal cells (BMSCs) and Niaspan, an agent which increases high density lipoprotein (HDL), each induces neurorestorative effects and promotes white matter remodeling after stroke in non-diabetic rats. In this study, we test whether combination of BMSCs with Niaspan induces an enhanced white matter remodeling in the ischemic brain of diabetic rats.

Research design and methods

Type-1 diabetes (T1DM) rats were subjected to transient middle cerebral artery occlusion (MCAo) and treated with or without BMSCs; Niaspan; and the combination of BMSCs + Niaspan daily for 14 days after MCAo. Immunostaining for white matter remodeling and synaptic protein expression including NG2; CNPase; BS (Bielschowsky silver); LFB (luxol fast blue); Synaptophysin and SMI-31 immunostaining were performed.

Results

BMSC monotherapy did not regulate NG2 and CNPase expression compared to T1DM control rats. Both, combination of BMSCs + Niaspan treatment, and Niaspan monotherapy significantly increase NG2 and CNPase expression compared to T1DM control. While combination BMSC+Niaspan, BMSC monotherapy and Niaspan monotherapy groups all increase BS, LFB, synaptophysin, and SMI-31 expression in the ischemic brain compared to T1DM-MCAo control. In addition, the combination treatment significantly enhances LFB, SMI-31, and Synaptophysin expression compared to BMSC monotherapy.

Conclusions

Combination treatment of stroke with BMSCs and Niaspan in T1DM rats increases white matter remodeling and additively increases BMSC monotherapy induced myelination and synaptic plasticity after stroke in T1DM rats.

ROCK mediates the inflammatory response in thrombin induced microglia

To investigate whether the ROCK pathway is involved in thrombin-induced microglial inflammatory response, thrombin-induced microglia were pretreated with the thrombin inhibitor argatroban or a ROCK inhibitor Y-27632. Microglial inflammatory response was evaluated by phagocytosis of fluorescein labeled latex beads analyses and inflammatory mediators' expression such as nitric oxide (NO) and tumor necrosis factor-alpha (TNF-а). Compared to non-induced microglia, thrombin-induced microglia show significantly enhanced phagocytotic capacity and increased ROCK, NO and TNF-а expression. Pretreatment of thrombin-induced microglia with argatroban or Y-27632 significantly decreased phagocytotic capacity and reduced ROCK, NO and TNF-α expression. Therefore, the ROCK pathway may play a vital role in the mechanisms by which thrombin induces microglia in the inflammatory response.

Intracranial aneurysm formation in type-one diabetes rats

BACKGROUND & OBJECTIVE

Diabetes mellitus (DM) plays an important role in the pathogenesis of vascular complications including arteriosclerosis and ischemic stroke. Whether DM impacts intracranial aneurysm (IA) formation has not been extensively investigated. In this study, we tested the underlying mechanism of type one DM (T1DM) induced IA formation in rats.

EXPERIMENTAL APPROACHES

T1DM was induced by streptozotocin injection. Rats were euthanized at 0, 4 and 10 weeks after T1DM induction. To evaluate cerebral vascular perfusion, Fluorescein isothiocyanate - dye was injected at 5 min prior to euthanasia. Vascular perfusion was measured by laser scanning confocal microscopy. Trichrome, Elastica van Gieson, alpha-smooth muscle actin (a-SMA) and receptor of advanced glycation end-products (RAGE), toll-like receptor 4 (TLR4) and matrix metalloproteinase 9 (MMP9) immunostaining were performed. The IA formation was classified by 0-3 stages: 0: Normal; 1: Endothelial damage; 2: Moderate protrusion; and 3: Saccular aneurysm formation.

RESULTS

T1DM significantly increased IA formation identified by the classification of aneurysmal changes compared with non-DM rats (p<0.05). However, T1DM induced IA formations were classified as stage 1 and stage 2, but not stage 3. Cerebral vascular perfusion was significantly decreased in T1DM rats compared to non-DM rats (p<0.01). DM10W rats exhibited a significant decrease of cerebral vascular perfusion compared to DM4W rats (p<0.05). T1DM rats also significantly increased the internal carotid artery (ICA) intimae and media thickness, and decreased the internal carotid artery diameter compared to non-DM rats. RAGE, MMP9 and TLR4 expression were significantly increased in T1DM rats compared to non-DM rats. The increased RAGE, TLR4 and MMP9 significantly correlated with IA formation (p<0.05).

CONCLUSION

T1DM increases IA formation. The increased RAGE, MMP9 and TLR4 expressions might contribute to IA formation in T1DM rats.

The immune system in stroke: clinical challenges and their translation to experimental research

Stroke represents an unresolved challenge for both developed and developing countries and has a huge socio-economic impact. Although considerable effort has been made to limit stroke incidence and improve outcome, strategies aimed at protecting injured neurons in the brain have all failed. This failure is likely to be due to both the incompleteness of modelling the disease and its causes in experimental research, and also the lack of understanding of how systemic mechanisms lead to an acute cerebrovascular event or contribute to outcome. Inflammation has been implicated in all forms of brain injury and it is now clear that immune mechanisms profoundly influence (and are responsible for the development of) risk and causation of stroke, and the outcome following the onset of cerebral ischemia. Until very recently, systemic inflammatory mechanisms, with respect to common comorbidities in stroke, have largely been ignored in experimental studies. The main aim is therefore to understand interactions between the immune system and brain injury in order to develop novel therapeutic approaches. Recent data from clinical and experimental research clearly show that systemic inflammatory diseases -such as atherosclerosis, obesity, diabetes or infection - similar to stress and advanced age, are associated with dysregulated immune responses which can profoundly contribute to cerebrovascular inflammation and injury in the central nervous system. In this review, we summarize recent advances in the field of inflammation and stroke, focusing on the challenges of translation between pre-clinical and clinical studies, and potential anti-inflammatory/immunomodulatory therapeutic approaches.

Rosmarinic acid protects against experimental diabetes with cerebral ischemia: relation to inflammation response

BACKGROUND

Inflammatory activation plays a vital role in the pathophysiological mechanisms of stroke, exerting deleterious effects on the progression of tissue damage and may lead to the vascular damage in diabetes. The objectives of this study were to determine the effects of rosmarinic acid (RA) on a cultured neuronal cell line, SH-SY5Y in vitro and experimental ischemic diabetic stroke in vivo.

METHODS

For oxygen-glucose deprivation (OGD) and tumor necrosis factor-α (TNF-α) stimulated SH-SY5Y cell line in vitro, SH-SY5Y cells were incubated with RA. For an in vivo experiment, diabetic rats were subjected to middle cerebral artery occlusion (MACO) for 40 minutes followed by reperfusion for 23 h.

RESULTS

Treatment of SH-SY5Y cells with RA reduced the OGD-induced apoptosis and cytotoxicity, blocked TNF-α-induced nuclear transcription factor κB (NF-κB) activation, and decreased high-mobility group box1 (HMGB1) expression. At doses higher than 50 mg/kg, RA produced a significant neuroprotective potential in rats with ischemia and reperfusion (I/R). RA (50 mg/kg) demonstrated significant neuroprotective activity even after delayed administration at 1 h, 3 h and 5 h after I/R. RA 50 mg/kg attenuated histopathological damage, decreased brain edema, inhibited NF-κB activation and reduced HMGB1 expression.

CONCLUSION

These data show that RA protects the brain against I/R injury with a favorable therapeutic time-window by alleviating diabetic cerebral I/R injury and attenuating blood-brain barrier (BBB) breakdown, and its protective effects may involve HMGB1 and the NF-κB signaling pathway.