myelin-basic-protein and Infarction--Middle-Cerebral-Artery

The neuroprotective effects of hypothermia in acute ischemic stroke are well documented. However, the mechanisms involved in the effects remain to be clearly elucidated and the role of hypothermia on long-term white matter integrity after acute ischemic stroke has yet to be investigated.. To investigate the role of mild focal hypothermia on long-term white matter (WM) integrity after transient cerebral ischemia.. Mild focal hypothermia treatment immediately after ischemic stroke significantly promotes WM integrity 28 days after the occlusion of the middle cerebral artery (MCAO) in mice. Higher integrity of white matter, lower activation of total microglia, less infarct volume, and better neurobehavioral function were detected in hypothermia-treated mice compared to normothermia-treated mice. Furthermore, we found that hypothermia could decrease detrimental M1 phenotype microglia and promote healthy M2 phenotype microglia. In vitro, results also indicated that hypothermia promoted oligodendrocytes differentiation and maturation after oxygen glucose deprivation.. Hypothermia promotes long-term WM integrity and inhibits neuroinflammation in a mouse model of ischemic brain injury.

Topics: Animals; Animals, Newborn; Antigens; Antigens, CD; Brain; Brain Infarction; Calcium-Binding Proteins; Cell Hypoxia; Cells, Cultured; Cerebrum; Disease Models, Animal; Gene Expression Regulation; Glucose; Hypothermia, Induced; Infarction, Middle Cerebral Artery; Leukoencephalopathies; Male; Maze Learning; Mice; Mice, Inbred C57BL; Microfilament Proteins; Myelin Basic Protein; Neurofilament Proteins; Oligodendroglia; Proteoglycans; Rats; Rats, Sprague-Dawley; RNA, Messenger; Rotarod Performance Test; Time Factors

Cell therapy has emerged as a potential treatment for many neurodegenerative diseases including stroke and neonatal ischemic brain injury. Delayed intranasal administration of mesenchymal stem cells (MSCs) after experimental hypoxia-ischemia and after a transient middle cerebral artery occlusion (tMCAO) in neonatal rats has shown improvement in long-term functional outcomes, but the effects of MSCs on white matter injury (WMI) are insufficiently understood. In this study we used longitudinal T2-weighted (T2W) and diffusion tensor magnetic resonance imaging (MRI) to characterize chronic injury after tMCAO induced in postnatal day 10 (P10) rats and examined the effects of delayed MSC administration on WMI, axonal coverage, and long-term somatosensory function. We show unilateral injury- and region-dependent changes in diffusion fraction anisotropy 1 and 2 weeks after tMCAO that correspond to accumulation of degraded myelin basic protein, astrocytosis, and decreased axonal coverage. With the use of stringent T2W-based injury criteria at 72 hr after tMCAO to randomize neonatal rats to receive intranasal MSCs or vehicle, we show that a single MSC administration attenuates WMI and enhances somatosensory function 28 days after stroke. A positive correlation was found between MSC-enhanced white matter integrity and functional performance in injured neonatal rats. Collectively, these data indicate that the damage induced by tMCAO progresses over time and is halted by administration of MSCs. © 2016 Wiley Periodicals, Inc.

Topics: Age Factors; Analysis of Variance; Animals; Animals, Newborn; Bromodeoxyuridine; Cell- and Tissue-Based Therapy; Disease Models, Animal; Gene Expression Regulation, Developmental; Glial Fibrillary Acidic Protein; Image Processing, Computer-Assisted; Infarction, Middle Cerebral Artery; Lectins; Magnetic Resonance Imaging; Mesenchymal Stem Cells; Myelin Basic Protein; Psychomotor Disorders; Rats; Rats, Sprague-Dawley; White Matter

Macrophages are involved in demyelination in many brain diseases. However, the role of macrophages in the recovery phase of the ischemic brain is unknown. The present study aims to explore the role of macrophages in the ischemic brain injury and tissue repair following a 90-min transient middle cerebral artery occlusion in mice.. Clodronate liposomes were injected into mice to deplete periphery macrophages. These mice subsequently underwent middle cerebral artery occlusion. F4/80(+) and CD68(+) cells were examined in the mouse spleen and brain to confirm macrophage depletion at 14 days after middle cerebral artery occlusion. Modified neurological severity scores were used to evaluate the behavioral function between 1 and 14 days after middle cerebral artery occlusion. MBP, Iba1, and CD31 immunostaining were performed to determine myelin lesion, microglia activation, and microvessel density.. Clodronate liposomes depleted 80 % of the macrophages in the mouse spleen and reduced macrophage infiltration in the mouse brain. Macrophage depletion reduced the myelin damage in the ipsilateral striatum and microglia activation in both the ipsilateral cortex and striatum, enhanced the microvessel density in the peri-infarct region, attenuated brain atrophy, and promoted neurological recovery following middle cerebral artery occlusion.. Our results suggested that macrophage depletion is a potential intervention that can promote tissue repair and remodeling after brain ischemia, reduce demyelination and microglia activation, and enhance focal microvessel density.

Topics: Analysis of Variance; Animals; Antigens, CD; Bone Density Conservation Agents; Brain; Brain Injuries; Calcium-Binding Proteins; Clodronic Acid; Disease Models, Animal; Flow Cytometry; Gene Expression Regulation; Infarction, Middle Cerebral Artery; Macrophages; Male; Mice; Mice, Inbred ICR; Microfilament Proteins; Microglia; Microvessels; Myelin Basic Protein; Time Factors

Thymosin β4 (Tβ4) is a 5K actin binding peptide. Tβ4 improves neurological outcome in a rat model of embolic stroke and research is now focused on optimizing its dose for clinical trials. The purpose of this study was to perform a dose-response study of Tβ4 to determine the optimal dose of neurological improvement in a rat model of embolic stroke.. Male Wistar rats were subjected to embolic middle cerebral artery occlusion (MCAo). Rats were divided into 4 groups of 10 animals/group: control, 2, 12 and 18 mg/kg. Tβ4 was administered intraperitoneally 24h after MCAo and then every 3 days for 4 additional doses in a randomized controlled fashion. Neurological tests were performed after MCAo and before treatment and up to 8 weeks after treatment. The rats were sacrificed 56 days after MCAo and lesion volumes measured. Generalized estimating equation was used to compare the treatment effect on long term functional recovery at day 56. A quartic regression model was used for an optimal dose determination.. Tβ4 significantly improved neurological outcome at dose of 2 and 12 mg/kg at day 14 and extended to day 56 (p-values <0.05). The higher dose of 18 mg/kg did not show significant improvement. The estimated optimal dose of 3.75 mg/kg would provide optimal neurological improvement.. This study shown that Tβ4 significantly improved the long term neurological functional recovery at day 56 after MCAo with an optimal dose of 3.75 mg/kg. These results provide preclinical data for human clinical trials.

Topics: Acute Disease; Adenomatous Polyposis Coli; Animals; Brain; Bromodeoxyuridine; Disease Models, Animal; Dose-Response Relationship, Drug; Infarction, Middle Cerebral Artery; Male; Myelin Basic Protein; Neuroimaging; Neurologic Examination; Rats; Stroke; Thymosin; Time Factors; Treatment Outcome; Versicans

Anamnestic recall of stroke-related deficits is a common clinical observation, especially during periods of systemic infection. The pathophysiology of this transient re-emergence of neurological dysfunction is unknown.. Male Lewis rats underwent 3 hours middle cerebral artery occlusion and were treated with lipopolysaccharide or saline at the time of reperfusion. The delayed-type hypersensitivity (DTH) response to myelin basic protein was examined 28 days after middle cerebral artery occlusion. Changes in behavioral outcomes were assessed after DTH testing and repeat administration of lipopolysaccharide or saline at 34 days. At the time of euthanasia (36 days), the immunologic response of splenocytes to myelin basic protein, neuron-specific enolase, and proteolipid protein was determined by enzyme-linked immunospot assay and the number of lymphocytes in the brain determined by immunocytochemistry.. Animals treated with lipopolysaccharide at middle cerebral artery occlusion had a greater DTH response to myelin basic protein than animals treated with saline. Among those animals that had fully recovered on a given behavioral test before DTH testing, those treated with lipopolysaccharide at middle cerebral artery occlusion displayed more neurological deterioration after DTH testing and had more CD8(+) lymphocytes within the ischemic core of the brain. Furthermore, the Th1 immune response to brain antigens in the spleen was more robust among those animals that deteriorated after DTH testing and there were more CD4(+) lymphocytes in the penumbral region of animals with a Th1 response to myelin basic protein.. Our data suggest that an immune response to the brain contributes to the phenomenon of anamnestic recall of stroke-related deficits after an infection. The contribution of the immune response to this phenomenon deserves further investigation.

Topics: Amnesia; Animals; Brain; Hypersensitivity, Delayed; Immune System; Infarction, Middle Cerebral Artery; Lipopolysaccharides; Male; Models, Animal; Myelin Basic Protein; Nervous System Diseases; Rats; Rats, Inbred Lew; Stroke; Th1 Cells; Time Factors

Animals subjected to an inflammatory insult at the time of stroke are predisposed to the development of an inflammatory autoimmune response to brain. This response is associated with worse neurological outcome. Because induction of immunologic tolerance to brain antigens before stroke onset is associated with improved outcome, we sought to determine whether this paradigm could prevent the deleterious autoimmune response to brain provoked by an inflammatory stimulus at the time of ischemia.. Male Lewis rats were tolerized to myelin basic protein (MBP) or ovalbumin by intranasal administration before middle cerebral artery occlusion. At the time of reperfusion, all animals received lipopolysaccharide (1 mg/kg intraperitoneal). Behavioral tests were performed at set time intervals.. One month after middle cerebral artery occlusion, lymphocytes from the spleens of MBP-tolerized animals were less likely to evidence an autoimmune response and more likely to evidence a regulatory response (Treg) toward MBP than those from ovalbumin-tolerized animals. Animals that had an inflammatory response toward MBP (a Th1 response) performed worse on behavioral tests than those that did not. Fractalkine, a surrogate marker of inflammation, was elevated in animals with a Th1 response to MBP.. These data extend our previous findings and suggest that deleterious autoimmunity to brain antigens can be prevented by prophylactically inducing regulatory T-cell responses to those antigens.

Topics: Administration, Intranasal; Animals; Autoimmune Diseases of the Nervous System; Autoimmunity; Biomarkers; Chemokine CX3CL1; Encephalitis; Immune Tolerance; Immunity, Cellular; Immunotherapy; Infarction, Middle Cerebral Artery; Male; Myelin Basic Protein; Ovalbumin; Rats; Rats, Inbred Lew; Stroke; T-Lymphocytes, Regulatory; Treatment Outcome

After stroke, the blood-brain barrier is transiently disrupted, allowing leukocytes to enter the brain and brain antigens to enter the peripheral circulation. This encounter of normally sequestered brain antigens by the systemic immune system could therefore present an opportunity for an autoimmune response to brain to occur after stroke. In this study, we assessed the immune response to myelin basic protein (MBP) in animals subjected to middle cerebral artery occlusion (MCAO). Some animals received an intraperitoneal injection of lipopolysaccharide (LPS; 1 mg/kg) at reperfusion to stimulate a systemic inflammatory response. At 1 month after MCAO, animals exposed to LPS were more likely to be sensitized to MBP (66.7% versus 22.2%; P=0.007) and had more profound and persistent neurologic deficits than non-LPS-treated animals. Exposure to LPS was associated with increased expression of the costimulatory molecule B7.1 early after stroke onset (P=0.009) and increased brain atrophy 1 month after MCAO (P=0.03). These data suggest that animals subjected to a systemic inflammatory insult at the time of stroke are predisposed to develop an autoimmune response to brain, and that this response is associated with worse outcome. These data may partially explain why patients who become infected after stroke experience increased morbidity.

Topics: Animals; Atrophy; Autoantigens; Behavior, Animal; Blood-Brain Barrier; Brain; CD4-Positive T-Lymphocytes; Gram-Negative Bacteria; Infarction, Middle Cerebral Artery; Lipopolysaccharides; Male; Myelin Basic Protein; Rats; Rats, Inbred Lew

White matter of the neonatal brain is highly sensitive to hypoxic-ischemic insult. The susceptibility of premature oligodendrocytes (OLs) to free radicals (FRs) produced during hypoxia-ischemia (HI) has been proposed as one of the mechanisms involved. To test this hypothesis, and to further investigate if the FR scavenger alpha-phenyl-N-tert-butyl-nitrone (PBN) attenuates hypoxic-ischemic white matter damage (WMD), postnatal day 4 (P4) SD rats were subjected to bilateral common carotid artery ligation (BCAL), followed by 8% oxygen exposure for 20 min. Pathological changes were evaluated on P6 and P9, 2 and 5 days after the HI insult. HI caused severe WMD including rarefaction, necrosis and cavity formation in the corpus callosum, external and internal capsule areas. OL injury was evidenced by degeneration of O4 positive OLs on P6. Disrupted myelination was verified by decreased immunostaining of myelin basic protein (MBP) on P9. Axonal injury was demonstrated by increased amyloid precursor protein (APP) immunostaining on both P6 and P9. Two lipid peroxidation end products, malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), showed a one-fold elevation within 1-24 h following HI. 4-HNE immunostaining was found to specifically localize in the white matter area. Furthermore, pyknotic O4+ OLs were double-labeled with 4-HNE. These findings suggest that FRs are involved in the pathogenesis of neonatal WMD. PBN (100 mg/kg, i.p.) treatment alleviated the pathological changes of WMD following HI. It improved the survival of O4 positive OLs, attenuated hypomyelination and reduced axonal damage. PBN treatment also decreased the brain concentration of MDA/4-HNE and positive 4-HNE staining in the white matter area. These findings indicate that in the current WMD model, PBN protects both OLs and axons, the two main components in the white matter, from neonatal HI insult. FR scavenging appears to be the primary mechanism underlying its neuroprotective effect.

Topics: Age Factors; Aldehydes; Amyloid beta-Peptides; Analysis of Variance; Animals; Animals, Newborn; Antigens, Differentiation; Brain; Cell Count; Cell Survival; Cyclic N-Oxides; Free Radical Scavengers; Hypoxia-Ischemia, Brain; Immunohistochemistry; Infarction, Middle Cerebral Artery; Malondialdehyde; Myelin Basic Protein; Nitrogen Oxides; Oligodendroglia; Rats; Staining and Labeling; Time Factors