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Kalyani P, Lippa SM, Werner JK, Amyot F, Moore CB, Kenney K, Diaz-Arrastia R. Phosphodiesterase-5 (PDE-5) Inhibitors as Therapy for Cerebrovascular Dysfunction in Chronic Traumatic Brain Injury. Neurotherapeutics 2023; 20:1629-1640. [PMID: 37697134 PMCID: PMC10684467 DOI: 10.1007/s13311-023-01430-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2023] [Indexed: 09/13/2023] Open
Abstract
Multiple phase III randomized controlled trials (RCTs) for pharmacologic interventions in traumatic brain injury (TBI) have failed despite promising results in experimental models. The heterogeneity of TBI, in terms of pathomechanisms and impacted brain structures, likely contributes to these failures. Biomarkers have been recommended to identify patients with relevant pathology (predictive biomarkers) and confirm target engagement and monitor therapy response (pharmacodynamic biomarkers). Our group focuses on traumatic cerebrovascular injury as an understudied endophenotype of TBI and is validating a predictive and pharmacodynamic imaging biomarker (cerebrovascular reactivity; CVR) in moderate-severe TBI. We aim to extend these studies to milder forms of TBI to determine the optimal dose of sildenafil for maximal improvement in CVR. We will conduct a phase II dose-finding study involving 160 chronic TBI patients (mostly mild) using three doses of sildenafil, a phosphodiesterase-5 (PDE-5) inhibitor. The study measures baseline CVR and evaluates the effect of escalating sildenafil doses on CVR improvement. A 4-week trial of thrice daily sildenafil will assess safety, tolerability, and clinical efficacy. This dual-site 4-year study, funded by the Department of Defense and registered in ClinicalTrials.gov (NCT05782244), plans to launch in June 2023. Biomarker-informed RCTs are essential for developing effective TBI interventions, relying on an understanding of underlying pathomechanisms. Traumatic microvascular injury (TMVI) is an attractive mechanism which can be targeted by vaso-active drugs such as PDE-5 inhibitors. CVR is a potential predictive and pharmacodynamic biomarker for targeted interventions aimed at TMVI. (Trial registration: NCT05782244, ClinicalTrials.gov ).
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Affiliation(s)
- Priyanka Kalyani
- Department of Neurology, University of Pennsylvania, 3400 Spruce St, Philadelphia, PA, 19104, USA.
| | - Sara M Lippa
- Walter Reed National Military Medical Center, The National Intrepid Center of Excellence, Palmer Rd S, Bethesda, MD, 20814, USA
- Department of Neuroscience, Uniformed Services University Health Sciences, 4301, Jones Bridge Rd, Bethesda, MD, 20814, USA
| | - J Kent Werner
- Walter Reed National Military Medical Center, The National Intrepid Center of Excellence, Palmer Rd S, Bethesda, MD, 20814, USA
- Department of Neuroscience, Uniformed Services University Health Sciences, 4301, Jones Bridge Rd, Bethesda, MD, 20814, USA
| | - Franck Amyot
- Walter Reed National Military Medical Center, The National Intrepid Center of Excellence, Palmer Rd S, Bethesda, MD, 20814, USA
| | - Carol B Moore
- Department of Neuroscience, Uniformed Services University Health Sciences, 4301, Jones Bridge Rd, Bethesda, MD, 20814, USA
| | - Kimbra Kenney
- Department of Neuroscience, Uniformed Services University Health Sciences, 4301, Jones Bridge Rd, Bethesda, MD, 20814, USA
| | - Ramon Diaz-Arrastia
- Department of Neurology, University of Pennsylvania, 3400 Spruce St, Philadelphia, PA, 19104, USA
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Torrens JN, Hetzer SM, Evanson NK. Brief Oxygen Exposure after Traumatic Brain Injury Hastens Recovery and Promotes Adaptive Chronic Endoplasmic Reticulum Stress Responses. Int J Mol Sci 2023; 24:9831. [PMID: 37372978 DOI: 10.3390/ijms24129831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 06/02/2023] [Accepted: 06/05/2023] [Indexed: 06/29/2023] Open
Abstract
Traumatic brain injury (TBI) is a major public health concern, particularly in adolescents who have a higher mortality and incidence of visual pathway injury compared to adult patients. Likewise, we have found disparities between adult and adolescent TBI outcomes in rodents. Most interestingly, adolescents suffer a prolonged apneic period immediately post-injury, leading to higher mortality; therefore, we implemented a brief oxygen exposure paradigm to circumvent this increased mortality. Adolescent male mice experienced a closed-head weight-drop TBI and were then exposed to 100% O2 until normal breathing returned or recovered in room air. We followed mice for 7 and 30 days and assessed their optokinetic response; retinal ganglion cell loss; axonal degeneration; glial reactivity; and retinal ER stress protein levels. O2 reduced adolescent mortality by 40%, improved post-injury visual acuity, and reduced axonal degeneration and gliosis in optical projection regions. ER stress protein expression was altered in injured mice, and mice given O2 utilized different ER stress pathways in a time-dependent manner. Finally, O2 exposure may be mediating these ER stress responses through regulation of the redox-sensitive ER folding protein ERO1α, which has been linked to a reduction in the toxic effects of free radicals in other animal models of ER stress.
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Affiliation(s)
- Jordyn N Torrens
- Division of Pediatric Rehabilitation Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Shelby M Hetzer
- Neuroscience Graduate Program, University of Cincinnati, Cincinnati, OH 45267, USA
| | - Nathan K Evanson
- Division of Pediatric Rehabilitation Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
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Amyot F, Davis C, Sangobowale M, Moore C, Silverman E, Gandjbakhche A, Diaz-Arrastia R, Kenney K. Cerebrovascular Reactivity Measurement with Functional Near Infrared Spectroscopy. J Vis Exp 2022:10.3791/61284. [PMID: 35723463 PMCID: PMC11189107 DOI: 10.3791/61284] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/22/2024] Open
Abstract
Cerebrovascular reactivity (CVR) is the capacity of blood vessels in the brain to alter cerebral blood flow (either with dilation or constriction) in response to chemical or physical stimuli. The amount of reactivity in the cerebral microvasculature depends on the integrity of the capacitance vasculature and is the primary function of endothelial cells. CVR is, therefore, an indicator of the microvasculature's physiology and overall health. Imaging methods that can measure CVR are available but can be costly, and require magnetic resonance imaging centers and technical expertise. In this study, we used fNIRS technology to monitor changes of oxyhemoglobin (HbO) and deoxyhemoglobin (HbR) in the cerebral microvasculature to assess the CVR of 15 healthy controls (HC) in response to a vasoactive stimulus (inhaled 5% carbon dioxide or CO2). Our results suggest that this is a promising imaging technology that offers a non-invasive, accurate, portable, and cost-effective method of mapping cortical CVR and associated microvasculature function, resulting from a traumatic brain injury or other conditions associated with cerebral microvasculopathy.
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Affiliation(s)
- Franck Amyot
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center;
| | - Cora Davis
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center
| | | | - Carol Moore
- Uniformed Services University of the Health Sciences
| | | | - Amir Gandjbakhche
- The Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health
| | | | - Kimbra Kenney
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center; Uniformed Services University of the Health Sciences
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Haber M, Amyot F, Lynch CE, Sandsmark DK, Kenney K, Werner JK, Moore C, Flesher K, Woodson S, Silverman E, Chou Y, Pham D, Diaz-Arrastia R. Imaging biomarkers of vascular and axonal injury are spatially distinct in chronic traumatic brain injury. J Cereb Blood Flow Metab 2021; 41:1924-1938. [PMID: 33444092 PMCID: PMC8327117 DOI: 10.1177/0271678x20985156] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Revised: 10/07/2020] [Accepted: 12/06/2020] [Indexed: 11/17/2022]
Abstract
Traumatic Brain Injury (TBI) is associated with both diffuse axonal injury (DAI) and diffuse vascular injury (DVI), which result from inertial shearing forces. These terms are often used interchangeably, but the spatial relationships between DAI and DVI have not been carefully studied. Multimodal magnetic resonance imaging (MRI) can help distinguish these injury mechanisms: diffusion tensor imaging (DTI) provides information about axonal integrity, while arterial spin labeling (ASL) can be used to measure cerebral blood flow (CBF), and the reactivity of the Blood Oxygen Level Dependent (BOLD) signal to a hypercapnia challenge reflects cerebrovascular reactivity (CVR). Subjects with chronic TBI (n = 27) and healthy controls (n = 14) were studied with multimodal MRI. Mean values of mean diffusivity (MD), fractional anisotropy (FA), CBF, and CVR were extracted for pre-determined regions of interest (ROIs). Normalized z-score maps were generated from the pool of healthy controls. Abnormal ROIs in one modality were not predictive of abnormalities in another. Approximately 9-10% of abnormal voxels for CVR and CBF also showed an abnormal voxel value for MD, while only 1% of abnormal CVR and CBF voxels show a concomitant abnormal FA value. These data indicate that DAI and DVI represent two distinct TBI endophenotypes that are spatially independent.
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Affiliation(s)
- Margalit Haber
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Franck Amyot
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, USA
| | - Cillian E Lynch
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Danielle K Sandsmark
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Kimbra Kenney
- National Intrepid Center of Excellence, Walter Reed National Military Medical Center, Bethesda, MD, USA
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - John K Werner
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Carol Moore
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Kelley Flesher
- Department of Neurology, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
| | - Sarah Woodson
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Erika Silverman
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Yiyu Chou
- Center for Neuroscience and Regenerative Medicine, Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Dzung Pham
- Center for Neuroscience and Regenerative Medicine, Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, USA
| | - Ramon Diaz-Arrastia
- Department of Neurology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
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Kenney K, Amyot F, Moore C, Haber M, Turtzo LC, Shenouda C, Silverman E, Gong Y, Qu BX, Harburg L, Wassermann EM, Lu H, Diaz‐Arrastia R. Phosphodiesterase-5 inhibition potentiates cerebrovascular reactivity in chronic traumatic brain injury. Ann Clin Transl Neurol 2018; 5:418-428. [PMID: 29687019 PMCID: PMC5899908 DOI: 10.1002/acn3.541] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 12/12/2017] [Accepted: 12/26/2017] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Traumatic cerebrovascular injury (TCVI), a common consequence of traumatic brain injury (TBI), presents an attractive therapeutic target. Because phosphodiesterase-5 (PDE5) inhibitors potentiate the action of nitric oxide (NO) produced by endothelial cells, they are candidate therapies for TCVI. This study aims to: (1) measure cerebral blood flow (CBF), cerebrovascular reactivity (CVR), and change in CVR after a single dose of sildenafil (ΔCVR) in chronic TBI compared to uninjured controls; (2) examine the safety and tolerability of 8-week sildenafil administration in chronic symptomatic moderate/severe TBI patients; and as an exploratory aim, (3) assess the effect of an 8-week course of sildenafil on chronic TBI symptoms. METHODS Forty-six subjects (31 chronic TBI, 15 matched healthy volunteers) were enrolled. Baseline CBF and CVR before and after administration of sildenafil were measured. Symptomatic TBI subjects then completed an 8-week double-blind, placebo-controlled, crossover trial of sildenafil. A neuropsychological battery and neurobehavioral symptom questionnaires were administered at each study visit. RESULTS After a single dose of sildenafil, TBI subjects showed a significant increase in global CVR compared to healthy controls (P < 0.001, d = 0.9). Post-sildenafil CVR maps showed near-normalization of CVR in many regions where baseline CVR was low, predominantly within areas without structural abnormalities. Sildenafil was well tolerated. Clinical Global Impression (CGI) scale showed a trend toward clinical improvement while on sildenafil treatment. FINDINGS Single-dose sildenafil improves regional CVR deficits in chronic TBI patients. CVR and ΔCVR are potential predictive and pharmacodynamic biomarkers of PDE5 inhibitor therapy for TCVI. Sildenafil is a potential therapy for TCVI.
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Affiliation(s)
- Kimbra Kenney
- Department of NeurologyUniformed Services University of the Health SciencesBethesdaMaryland
| | - Franck Amyot
- Department of NeurologyUniformed Services University of the Health SciencesBethesdaMaryland
| | - Carol Moore
- Department of NeurologyUniformed Services University of the Health SciencesBethesdaMaryland
| | - Margalit Haber
- Department of NeurologyUniversity of Pennsylvania Perelman School of MedicinePhiladelphiaPennsylvania
| | | | - Christian Shenouda
- Department of Physical Medicine and RehabilitationNational Institutes of Health Clinical CenterBethesdaMaryland
| | - Erika Silverman
- Department of NeurologyUniversity of Pennsylvania Perelman School of MedicinePhiladelphiaPennsylvania
| | - Yunhua Gong
- Department of NeurologyUniversity of Pennsylvania Perelman School of MedicinePhiladelphiaPennsylvania
| | - Bao‐ Xi Qu
- Department of NeurologyUniformed Services University of the Health SciencesBethesdaMaryland
| | - Leah Harburg
- Department of NeurologyUniformed Services University of the Health SciencesBethesdaMaryland
| | - Eric M. Wassermann
- Behavioral Neurology UnitNational Institute of Neurological Diseases and StrokeNational Institutes of HealthBethesdaMaryland
| | | | - Ramon Diaz‐Arrastia
- Department of NeurologyUniversity of Pennsylvania Perelman School of MedicinePhiladelphiaPennsylvania
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Amyot F, Kenney K, Moore C, Haber M, Turtzo LC, Shenouda C, Silverman E, Gong Y, Qu BX, Harburg L, Lu HY, Wassermann EM, Diaz-Arrastia R. Imaging of Cerebrovascular Function in Chronic Traumatic Brain Injury. J Neurotrauma 2018; 35:1116-1123. [PMID: 29065769 DOI: 10.1089/neu.2017.5114] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Traumatic cerebrovascular injury (TCVI) is a common pathologic mechanism of traumatic brain injury (TBI) and presents an attractive target for intervention. The aims of this study were to assess cerebral blood flow (CBF) and cerebrovascular reactivity (CVR) using magnetic resonance imaging (MRI) to assess their value as biomarkers of TCVI in chronic TBI, characterize the spatial distribution of TCVI, and assess the relationships between each biomarker and neuropsychological and clinical assessments. Forty-two subjects (27 chronic TBI, 15 age- and gender-matched healthy volunteers) were studied cross-sectionally. CBF was measured by arterial spin labeling and CVR by assessing the MRI-blood oxygen level-dependent signal with hypercapnia challenge. A focused neuropsychological battery adapted from the TBI Common Data Elements and neurobehavioral symptom questionnaires were administered at the time of the imaging session. Chronic TBI subjects showed a significant reduction in mean global, gray matter (GM), and white matter (WM) CVR, compared with healthy volunteers (p < 0.001). Mean GM CVR had the greatest effect size (Cohen's d = 0.9). CVR maps in chronic TBI subjects showed patchy, multifocal CVR deficits. CBF discriminated poorly between TBI subjects and healthy volunteers and did not correlate with CVR. Mean global CVR correlated best with chronic neurobehavioral symptoms among TBI subjects. Global, GM, and WM CVR are reliable and potentially useful biomarkers of TCVI in the chronic stage after moderate-to-severe TBI. CBF is less useful as biomarker of TCVI. CVR correlates best with chronic TBI symptoms. CVR has potential as a predictive and pharmacodynamic biomarker for interventions targeting TCVI.
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Affiliation(s)
- Franck Amyot
- 1 Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, Maryland
| | - Kimbra Kenney
- 1 Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, Maryland
| | - Carol Moore
- 1 Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, Maryland
| | - Margalit Haber
- 2 Department of Neurology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - L Christine Turtzo
- 3 Center for Neuroscience and Regenerative Medicine, National Institute of Neurological Disorder and Stroke, National Institutes of Health , Bethesda, Maryland
| | - Christian Shenouda
- 3 Center for Neuroscience and Regenerative Medicine, National Institute of Neurological Disorder and Stroke, National Institutes of Health , Bethesda, Maryland
| | - Erika Silverman
- 2 Department of Neurology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Yunhua Gong
- 2 Department of Neurology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
| | - Bao-Xi Qu
- 1 Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, Maryland
| | - Leah Harburg
- 1 Department of Neurology, Uniformed Services University of the Health Sciences , Bethesda, Maryland
| | - Hanzhang Y Lu
- 4 Department of Radiology and Radiological Science, Johns Hopkins University Baltimore , Maryland
| | - Eric M Wassermann
- 5 National Institute of Neurological Disorders and Stroke, National Institutes of Health , Bethesda, Maryland
| | - Ramon Diaz-Arrastia
- 2 Department of Neurology, University of Pennsylvania Perelman School of Medicine , Philadelphia, Pennsylvania
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Abstract
Traumatic brain injury (TBI) has become the signature injury of the military conflict in Iraq and Afghanistan and also has a high rate of occurrence in civilian populations in the United States. Although the effects of a moderate to severe brain injury have been investigated for decades, the chronic effects of single and repetitive mild TBI are just beginning to be investigated. Data suggest that the different types and severities of TBI have unique long-term outcomes and thus may represent different types of diseases. Therefore, this review outlines the causes, incidence, symptoms, and pathophysiology of mild, moderate, and severe TBI.
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Thelin EP, Frostell A, Mulder J, Mitsios N, Damberg P, Aski SN, Risling M, Svensson M, Morganti-Kossmann MC, Bellander BM. Lesion Size Is Exacerbated in Hypoxic Rats Whereas Hypoxia-Inducible Factor-1 Alpha and Vascular Endothelial Growth Factor Increase in Injured Normoxic Rats: A Prospective Cohort Study of Secondary Hypoxia in Focal Traumatic Brain Injury. Front Neurol 2016; 7:23. [PMID: 27014178 PMCID: PMC4780037 DOI: 10.3389/fneur.2016.00023] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2015] [Accepted: 02/15/2016] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Hypoxia following traumatic brain injury (TBI) is a severe insult shown to exacerbate the pathophysiology, resulting in worse outcome. The aim of this study was to investigate the effects of a hypoxic insult in a focal TBI model by monitoring brain edema, lesion volume, serum biomarker levels, immune cell infiltration, as well as the expression of hypoxia-inducible factor-1 alpha (HIF-1α) and vascular endothelial growth factor (VEGF). MATERIALS AND METHODS Female Sprague-Dawley rats (n = 73, including sham and naive) were used. The rats were intubated and mechanically ventilated. A controlled cortical impact device created a 3-mm deep lesion in the right parietal hemisphere. Post-injury, rats inhaled either normoxic (22% O2) or hypoxic (11% O2) mixtures for 30 min. The rats were sacrificed at 1, 3, 7, 14, and 28 days post-injury. Serum was collected for S100B measurements using ELISA. Ex vivo magnetic resonance imaging (MRI) was performed to determine lesion size and edema volume. Immunofluorescence was employed to analyze neuronal death, changes in cerebral macrophage- and neutrophil infiltration, microglia proliferation, apoptosis, complement activation (C5b9), IgG extravasation, HIF-1α, and VEGF. RESULTS The hypoxic group had significantly increased blood levels of lactate and decreased pO2 (p < 0.0001). On MRI post-traumatic hypoxia resulted in larger lesion areas (p = 0.0173), and NeuN staining revealed greater neuronal loss (p = 0.0253). HIF-1α and VEGF expression was significantly increased in normoxic but not in hypoxic animals (p < 0.05). A trend was seen for serum levels of S100B to be higher in the hypoxic group at 1 day after trauma (p = 0.0868). No differences were observed between the groups in cytotoxic and vascular edema, IgG extravasation, neutrophils and macrophage aggregation, microglia proliferation, or C5b-9 expression. CONCLUSION Hypoxia following focal TBI exacerbated the lesion size and neuronal loss. Moreover, there was a tendency to higher levels of S100B in the hypoxic group early after injury, indicating a potential validity as a biomarker of injury severity. In the normoxic group, the expression of HIF-1α and VEGF was found elevated, possibly indicative of neuro-protective responses occurring in this less severely injured group. Further studies are warranted to better define the pathophysiology of post-TBI hypoxia.
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Affiliation(s)
- Eric Peter Thelin
- Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden
| | - Arvid Frostell
- Department of Clinical Neuroscience, Karolinska Institutet , Stockholm , Sweden
| | - Jan Mulder
- Science for Life Laboratory, Department of Neuroscience, Karolinska Institutet , Stockholm , Sweden
| | - Nicholas Mitsios
- Science for Life Laboratory, Department of Neuroscience, Karolinska Institutet , Stockholm , Sweden
| | - Peter Damberg
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; Karolinska Experimental Research and Imaging Center, Karolinska Universitetssjukhuset Solna, Stockholm, Sweden
| | - Sahar Nikkhou Aski
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; Karolinska Experimental Research and Imaging Center, Karolinska Universitetssjukhuset Solna, Stockholm, Sweden
| | - Mårten Risling
- Department of Neuroscience, Karolinska Institutet , Stockholm , Sweden
| | - Mikael Svensson
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; Department of Neurosurgery, Karolinska University Hospital, Stockholm, Sweden
| | - Maria Cristina Morganti-Kossmann
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, VIC, Australia; Department of Child Health, Barrow Neurological Institute, Phoenix Children's Hospital, University of Arizona College of Medicine Phoenix, Phoenix, AZ, USA
| | - Bo-Michael Bellander
- Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden; Department of Neurosurgery, Karolinska University Hospital, Stockholm, Sweden
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Hellewell SC, Ziebell JM, Lifshitz J, Morganti-Kossmann MC. Impact Acceleration Model of Diffuse Traumatic Brain Injury. Methods Mol Biol 2016; 1462:253-266. [PMID: 27604723 DOI: 10.1007/978-1-4939-3816-2_15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The impact acceleration (I/A) model of traumatic brain injury (TBI) was developed to reliably induce diffuse traumatic axonal injury in rats in the absence of skull fractures and parenchymal focal lesions. This model replicates a pathophysiology that is commonly observed in humans with diffuse axonal injury (DAI) caused by acceleration-deceleration forces. Such injuries are typical consequences of motor vehicle accidents and falls, which do not necessarily require a direct impact to the closed skull. There are several desirable characteristics of the I/A model, including the extensive axonal injury produced in the absence of a focal contusion, the suitability for secondary insult modeling, and the adaptability for mild/moderate injury through alteration of height and/or weight. Furthermore, the trauma device is inexpensive and readily manufactured in any laboratory, and the induction of injury is rapid (~45 min per animal from weighing to post-injury recovery) allowing multiple animal experiments per day. In this chapter, we describe in detail the methodology and materials required to produce the rat model of I/A in the laboratory. We also review current adaptations to the model to alter injury severity, discuss frequent complications and technical issues encountered using this model, and provide recommendations to ensure technically sound injury induction.
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Affiliation(s)
- Sarah C Hellewell
- Canadian Military and Veterans' Clinical Rehabilitation Research Program, Faculty of Rehabilitation Medicine, University of Alberta, 3-48, Corbett Hall, Edmonton, AB, Canada, T6G 2G4.
| | - Jenna M Ziebell
- Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ, USA
- Department of Child Health, University of Arizona College of Medicine - Phoenix, Phoenix, AZ, USA
| | - Jonathan Lifshitz
- Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ, USA
- Department of Child Health, University of Arizona College of Medicine - Phoenix, Phoenix, AZ, USA
- Phoenix VA Healthcare System, Phoenix, AZ, USA
- Neuroscience Program, Department of Psychology, Arizona State University, Tempe, AZ, USA
| | - M Cristina Morganti-Kossmann
- Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ, USA
- Neuroscience Program, Department of Psychology, Arizona State University, Tempe, AZ, USA
- Department of Epidemiology and Preventive Medicine, Monash University and Australian New Zealand Intensive Care Research Centre, Melbourne, VIC, Australia
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Kenney K, Amyot F, Haber M, Pronger A, Bogoslovsky T, Moore C, Diaz-Arrastia R. Cerebral Vascular Injury in Traumatic Brain Injury. Exp Neurol 2016; 275 Pt 3:353-366. [DOI: 10.1016/j.expneurol.2015.05.019] [Citation(s) in RCA: 155] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 05/19/2015] [Accepted: 05/26/2015] [Indexed: 12/14/2022]
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Abstract
Traumatic brain injury (TBI) is one of the most common causes of death and disability, and cerebral hypoxia is a frequently occurring harmful secondary event in TBI patients. The hypoxic conditions that occur on the scene of accident, where the airways are often obstructed or breathing is in other ways impaired, could be reproduced using animal TBI models where oxygen delivery is strictly controlled throughout the entire experimental procedure. Monitoring physiological parameters of the animal is of utmost importance in order to maintain an adequate quality of the experiment. Peripheral oxygen saturation, O2 pressure (pO2) in the blood, or fraction of inhaled O2 (FiO2) could be used as goals to validate the hypoxic conditions. Different models of traumatic brain injury could be used to inflict desired injury type, whereas effects then could be studied using radiological, physiological and functional tests. In order to confirm that the brain has been affected by a hypoxic injury, appropriate substances in the affected cerebral tissue, cerebrospinal fluid, or serum should be analyzed.
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Abstract
Spinal cord injury (SCI) is a major health problem and is associated with a diversity of neurological symptoms. Pathophysiologically, dysfunction after SCI results from the culmination of tissue damage produced both by the primary insult and a range of secondary injury mechanisms. The application of hypothermia has been demonstrated to be neuroprotective after SCI in both experimental and human studies. The myriad of protective mechanisms of hypothermia include the slowing down of metabolism, decreasing free radical generation, inhibiting excitotoxicity and apoptosis, ameliorating inflammation, preserving the blood spinal cord barrier, inhibiting astrogliosis, promoting angiogenesis, as well as decreasing axonal damage and encouraging neurogenesis. Hypothermia has also been combined with other interventions, such as antioxidants, anesthetics, alkalinization and cell transplantation for additional benefit. Although a large body of work has reported on the effectiveness of hypothermia as a neuroprotective approach after SCI and its application has been translated to the clinic, a number of questions still remain regarding its use, including the identification of hypothermia's therapeutic window, optimal duration and the most appropriate rewarming rate. In addition, it is necessary to investigate the neuroprotective effect of combining therapeutic hypothermia with other treatment strategies for putative synergies, particularly those involving neurorepair.
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Affiliation(s)
- Jiaqiong Wang
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, the Lois Pope Life Center, Locator code (R-48), PO BOX 016960, Miami, FL 33136, USA.
| | - Damien D Pearse
- The Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, the Lois Pope Life Center, Locator code (R-48), PO BOX 016960, Miami, FL 33136, USA.
- The Department of Neurological Surgery, University of Miami Miller School of Medicine, the Lois Pope Life Center, Locator code (R-48), PO BOX 016960, Miami, FL 33136, USA.
- The Neuroscience Program, University of Miami Miller School of Medicine, the Lois Pope Life Center, Locator code (R-48), PO BOX 016960, Miami, FL 33136, USA.
- The Interdisciplinary Stem Cell Institute, University of Miami Miller School of Medicine, the Lois Pope Life Center, Locator code (R-48), PO BOX 016960, Miami, FL 33136, USA.
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Capillary transit time heterogeneity and flow-metabolism coupling after traumatic brain injury. J Cereb Blood Flow Metab 2014; 34:1585-98. [PMID: 25052556 PMCID: PMC4269727 DOI: 10.1038/jcbfm.2014.131] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Revised: 06/10/2014] [Accepted: 06/20/2014] [Indexed: 12/26/2022]
Abstract
Most patients who die after traumatic brain injury (TBI) show evidence of ischemic brain damage. Nevertheless, it has proven difficult to demonstrate cerebral ischemia in TBI patients. After TBI, both global and localized changes in cerebral blood flow (CBF) are observed, depending on the extent of diffuse brain swelling and the size and location of contusions and hematoma. These changes vary considerably over time, with most TBI patients showing reduced CBF during the first 12 hours after injury, then hyperperfusion, and in some patients vasospasms before CBF eventually normalizes. This apparent neurovascular uncoupling has been ascribed to mitochondrial dysfunction, hindered oxygen diffusion into tissue, or microthrombosis. Capillary compression by astrocytic endfeet swelling is observed in biopsies acquired from TBI patients. In animal models, elevated intracranial pressure compresses capillaries, causing redistribution of capillary flows into patterns argued to cause functional shunting of oxygenated blood through the capillary bed. We used a biophysical model of oxygen transport in tissue to examine how capillary flow disturbances may contribute to the profound changes in CBF after TBI. The analysis suggests that elevated capillary transit time heterogeneity can cause critical reductions in oxygen availability in the absence of 'classic' ischemia. We discuss diagnostic and therapeutic consequences of these predictions.
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Chatzipanteli K, Vitarbo E, Alonso OF, Bramlett HM, Dietrich WD. Temporal profile of cerebrospinal fluid, plasma, and brain interleukin-6 after normothermic fluid-percussion brain injury: effect of secondary hypoxia. Ther Hypothermia Temp Manag 2014; 2:167-75. [PMID: 23667780 DOI: 10.1089/ther.2012.0016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Interleukin-6 (IL-6) is a proinflammatory cytokine that may play multiple roles in the pathogenesis of traumatic brain injury (TBI). The present study determined time-dependent changes in IL-6 concentrations in vulnerable brain regions, cerebrospinal fluid (CSF) samples, and plasma after normothermic TBI. Because secondary insults are common in head injured patients, we also assessed the consequences of a post-traumatic secondary hypoxic insult on this pleiotropic cytokine. Male Sprague-Dawley rats were intubated, anesthetized, and underwent a moderate parasagittal fluid-percussion brain injury (1.8-2.1 atm, 37°C) followed by either 30 minutes of normoxic or hypoxic (pO₂ = 30-40 mmHg) gas levels. Rats were sacrificed 3, 6, or 24 hours after TBI or shamoperated procedures. Brain samples, including the ipsilateral cerebral cortex and hippocampus were dissected and analyzed. Plasma and CSF samples were collected at similar times and stored at -80°C until analysis. IL-6 levels were significantly increased ( p < 0.05) at 3, 6, and 24 hours in the cerebral cortex and at 6 hours in the hippocampus after TBI. IL-6 levels in the TBI normoxic group for both structures returned to control levels by 24 hours. Plasma levels of IL-6 were elevated at all time points, while CSF levels were high at 3 and 6 hours, but normalized by 24 hours. Post-traumatic hypoxia led to significantly elevated ( p < 0.05) IL-6 protein levels in the cerebral cortex at 24 hours compared to sham-operated controls. These findings demonstrate that moderate TBI leads to an early increase in IL-6 brain, plasma, and CSF protein levels. Secondary post-traumatic hypoxia, a common secondary injury mechanism, led to prolonged elevations in plasma IL-6 levels that may participate in the pathophysiology of this complicated TBI model.
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Erythropoietin improves motor and cognitive deficit, axonal pathology, and neuroinflammation in a combined model of diffuse traumatic brain injury and hypoxia, in association with upregulation of the erythropoietin receptor. J Neuroinflammation 2013; 10:156. [PMID: 24344874 PMCID: PMC3896698 DOI: 10.1186/1742-2094-10-156] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 12/05/2013] [Indexed: 01/12/2023] Open
Abstract
Background Diffuse axonal injury is a common consequence of traumatic brain injury (TBI) and often co-occurs with hypoxia, resulting in poor neurological outcome for which there is no current therapy. Here, we investigate the ability of the multifunctional compound erythropoietin (EPO) to provide neuroprotection when administered to rats after diffuse TBI alone or with post-traumatic hypoxia. Methods Sprague–Dawley rats were subjected to diffuse traumatic axonal injury (TAI) followed by 30 minutes of hypoxic (Hx, 12% O2) or normoxic ventilation, and were administered recombinant human EPO-α (5000 IU/kg) or saline at 1 and 24 hours post-injury. The parameters examined included: 1) behavioural and cognitive deficit using the Rotarod, open field and novel object recognition tests; 2) axonal pathology (NF-200); 3) callosal degradation (hematoxylin and eosin stain); 3) dendritic loss (MAP2); 4) expression and localisation of the EPO receptor (EpoR); 5) activation/infiltration of microglia/macrophages (CD68) and production of IL-1β. Results EPO significantly improved sensorimotor and cognitive recovery when administered to TAI rats with hypoxia (TAI + Hx). A single dose of EPO at 1 hour reduced axonal damage in the white matter of TAI + Hx rats at 1 day by 60% compared to vehicle. MAP2 was decreased in the lateral septal nucleus of TAI + Hx rats; however, EPO prevented this loss, and maintained MAP2 density over time. EPO administration elicited an early enhanced expression of EpoR 1 day after TAI + Hx compared with a 7-day peak in vehicle controls. Furthermore, EPO reduced IL-1β to sham levels 2 hours after TAI + Hx, concomitant to a decrease in CD68 positive cells at 7 and 14 days. Conclusions When administered EPO, TAI + Hx rats had improved behavioural and cognitive performance, attenuated white matter damage, resolution of neuronal damage spanning from the axon to the dendrite, and suppressed neuroinflammation, alongside enhanced expression of EpoR. These data provide compelling evidence of EPO’s neuroprotective capability. Few benefits were observed when EPO was administered to TAI rats without hypoxia, indicating that EPO’s neuroprotective capacity is bolstered under hypoxic conditions, which may be an important consideration when EPO is employed for neuroprotection in the clinic.
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Miyauchi T, Wei EP, Povlishock JT. Therapeutic targeting of the axonal and microvascular change associated with repetitive mild traumatic brain injury. J Neurotrauma 2013; 30:1664-71. [PMID: 23796228 DOI: 10.1089/neu.2013.2995] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Recent interest in mild traumatic brain injury (mTBI) has increased the recognition that repetitive mTBI occurring within the sports and military settings can exacerbate the adverse consequences of the initial injury. While multiple studies have recently reported the pathological, metabolic, and functional changes associated with repetitive mTBI, no consideration has been given to the development of therapeutic approaches to attenuate these abnormalities. In this study, we used the model of repetitive impact acceleration insult previously reported by our laboratory to cause no initial structural and functional changes, yet evoke dramatic change following second insult of the same intensity. Using this model, we employed established neuroprotective agents including FK506 and hypothermia that were administered 1 h after the second insult. Following either therapeutic intervention, changes of cerebral vascular reactivity to acetylcholine were assessed through a cranial window. Following the completion of the vascular studies, the animals were prepared to access the numbers of amyloid precursor protein (APP) positive axons, a marker of axonal damage. Following repetitive injury, cerebral vascular reactivity was dramatically preserved by either therapeutic intervention or the combination thereof compared to control group in which no intervention was employed. Similarly, APP density was significantly lower in the therapeutic intervention group compared in controls. Although the individual use of FK506 or hypothermia exerted significant protection, no additive benefit was found when both therapies were combined. In sum, the current study demonstrates that the exacerbated pathophysiological changes associated with repetitive mTBI can be therapeutically targeted.
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Affiliation(s)
- Takashi Miyauchi
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University Medical Center , Richmond, Virginia
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18
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Xiong M, Chen LX, Ma SM, Yang Y, Zhou WH. Short-term effects of hypothermia on axonal injury, preoligodendrocyte accumulation and oligodendrocyte myelination after hypoxia-ischemia in the hippocampus of immature rat brain. Dev Neurosci 2013; 35:17-27. [PMID: 23446161 DOI: 10.1159/000346324] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Accepted: 12/04/2012] [Indexed: 11/19/2022] Open
Abstract
Hypothermia is known to improve neurological recovery of animals and humans exposed to hypoxic-ischemic (HI) injury. However, the underlying mechanisms of the neuroprotective effects of hypothermia are only partially understood, including decreased excitotoxicity and apoptosis, and suppressed inflammation. There are few studies about the hypothermic effects on axonal injury and oligodendrocyte (OL) lineage degeneration, which are important components of neonatal brain injuries that cause cognitive disability. We hypothesized that mild hypothermia would reduce axonal injury and increase myelination in the hippocampus after HI. We performed left carotid artery ligation followed by 8% oxygen for 2 h in 7-day-old rats. Animals were divided into a hypothermic group (rectal temperature 32-33°C for 24 h) and a normothermic group (36-37°C for 24 h) immediately after HI. Animals were sacrificed at 1, 3 and 7 days for immunohistochemistry or Western blot analysis. We detected neuron loss by microtubule-associated protein 2 labeling and axonal injury by non-phosphorylated neurofilament (SMI32) with neurofilament 200 (NF200) double staining. We examined early OL progenitors by A2B5 or NG2, preoligodendrocytes (preOLs) by O4, and mature OLs by 2,3-cyclic nucleotide 3-phosphodiesterase (CNPase) and glutathione S-transferase (GST)-pi staining. Apoptosis was studied by active caspase-3. Hypothermia was associated with a significant elevation of neurons and axons in the hippocampal CA1 region after HI. Early OL progenitors (A2B5(+)) were elevated, but preOLs (O4(+)) and active caspase-3 were dramatically reduced in the hypothermic rat brain. Further study showed that the apoptotic rate of preOLs (caspase-3(+)-O4(+)/O4(+)) was markedly attenuated by hypothermic treatment compared to normothermic animals. The immunoreactivity of CNPase and GST-pi and the protein level of the myelin basic protein significantly increased in the hippocampus of hypothermia-treated rat brain. Axonal myelination also increased in hypothermic animals, which were tested by myelin basic protein and NF200 double staining and electron microscopy. These results showed that hypothermia reduced HI damage to axons and OL myelination coincided with increased early OL progenitor proliferation and decreased preOL accumulation and apoptosis. This study suggested new aspects that may contribute to elucidate the mechanism of hypothermic neuroprotection in neonatal rat brain.
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Affiliation(s)
- Man Xiong
- Key Laboratory of Neonatal Diseases, Ministry of Health, Children's Hospital, Fudan University, Shanghai, China
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Fujita M, Wei EP, Povlishock JT. Intensity- and interval-specific repetitive traumatic brain injury can evoke both axonal and microvascular damage. J Neurotrauma 2012; 29:2172-80. [PMID: 22559115 DOI: 10.1089/neu.2012.2357] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
In the experimental setting several investigators have recently reported exacerbations of the burden of axonal damage and other neuropathological changes following repetitive traumatic brain injuries (TBI) that were sustained at intervals from hours to days following the initial insult. These same studies also revealed that prolonging the interval between the first and second insult led to a reduction in the burden of neuropathological changes and/or their complete elimination. Although demonstrating the capability of repetitive TBI to evoke increased axonal and other neuropathological changes, these studies did not address the potential for concomitant microvascular dysfunction or damage, although vascular dysfunction has been implicated in the second-impact syndrome. In this study we revisit the issue of repetitive injury in a well-controlled animal model in which the TBI intensity was bracketed from subthreshold to threshold insults, while the duration of the intervals between the injuries varied. Employing cranial windows to assess vascular reactivity and post-mortem amyloid precursor protein (APP) analysis to determine the burden of axonal change, we recognized that subthreshold injuries, even when administered in repeated fashion over a short time frame, evoked neither axonal nor vascular change. However, with an elevation of insult intensity, repetitive injuries administered within 3-h time frames caused dramatic axonal damage and significant vascular dysfunction bordering on a complete loss of vasoreactivity. If, however, the interval between the repetitive injury was extended to 5 h, the burden of axonal change was reduced, as was the overall magnitude of the ensuing vascular dysfunction. With the extension of the interval between injuries to 10 h, neither axonal nor vascular changes were found. Collectively, these studies reaffirm the existence of significant axonal damage following repetitive TBI administered within a relatively short time frame. Additionally, they also demonstrate that these axonal changes parallel changes in the cerebral microcirculation, which also may have adverse consequences for the injured brain.
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Affiliation(s)
- Motoki Fujita
- Department of Anatomy and Neurobiology, Virginia Commonwealth University Medical Center, Richmond, Virginia, USA
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20
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Guilty molecules, guilty minds? The conflicting roles of the innate immune response to traumatic brain injury. Mediators Inflamm 2012; 2012:356494. [PMID: 22701273 PMCID: PMC3373171 DOI: 10.1155/2012/356494] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 03/26/2012] [Indexed: 12/11/2022] Open
Abstract
Traumatic brain injury (TBI) is a complex disease in the most complex organ of the body, whose victims endure lifelong debilitating physical, emotional, and psychosocial consequences. Despite advances in clinical care, there is no effective neuroprotective therapy for TBI, with almost every compound showing promise experimentally having disappointing results in the clinic. The complex and highly interrelated innate immune responses govern both the beneficial and deleterious molecular consequences of TBI and are present as an attractive therapeutic target. This paper discusses the positive, negative, and often conflicting roles of the innate immune response to TBI in both an experimental and clinical settings and highlights recent advances in the search for therapeutic candidates for the treatment of TBI.
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Fujita M, Oda Y, Wei EP, Povlishock JT. The combination of either tempol or FK506 with delayed hypothermia: implications for traumatically induced microvascular and axonal protection. J Neurotrauma 2012; 28:1209-18. [PMID: 21521034 DOI: 10.1089/neu.2011.1852] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Following traumatic brain injury (TBI), inhibition of reactive oxygen species and/or calcineurin can exert axonal and vascular protection. This protection proves optimal when these strategies are used early post-injury. Recent work has shown that the combination of delayed drug administration and delayed hypothermia extends this protection. Here we revisit this issue in TBI using the nitroxide antioxidant Tempol, or the immunophilin ligand FK506, together with delayed hypothermia, to determine their effects upon cerebral vascular reactivity and axonal damage. Animals were subjected to TBI and treated with Tempol at 30 or 90 min post-injury, or 90 min post-injury with concomitant mild hypothermia (33°C). Another group of animals were treated in the same fashion with the exception that they received FK506. Cranial windows were placed to assess vascular reactivity over 6 h post-injury, when the animals were assessed for traumatically induced axonal damage. Vasoreactivity was preserved by early Tempol administration; however, this benefit declined with time. The coupling of hypothermia and delayed Tempol, however, exerted significant vascular protection. The use of early and delayed FK506 provided significant vascular protection which was not augmented by hypothermia. The early administration of Tempol provided dramatic axonal protection that was not enhanced with hypothermia. Early and delayed FK506 provided significant axonal protection, although this protection was not enhanced by delayed hypothermia. The current investigation supports the premise that Tempol coupled with hypothermia extends its benefits. While FK506 proved efficacious with early and delayed administration, it did not provide either increased vascular or axonal benefit with hypothermia. These studies illustrate the potential benefits of Tempol coupled to delayed hypothermia. However, these findings do not transfer to the use of FK506, which in previous studies proved beneficial when coupled with hypothermia. These divergent results may be a reflection of the different animal models used and/or their associated injury severity.
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Affiliation(s)
- Motoki Fujita
- Department of Anatomy and Neurobiology, Virginia Commonwealth University Medical Center, Richmond, VA 23298, USA
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Fujita M, Wei EP, Povlishock JT. Effects of hypothermia on cerebral autoregulatory vascular responses in two rodent models of traumatic brain injury. J Neurotrauma 2012; 29:1491-8. [PMID: 22364620 DOI: 10.1089/neu.2011.2278] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Traumatic brain injury (TBI) can trigger disturbances of cerebral pressure autoregulation that can translate into the generation of secondary insults and increased morbidity/mortality. Few therapies have been developed to attenuate the damaging consequences of disturbed autoregulatory control, although some suggest that hypothermia may exert such protection. Here we reexamine this issue of traumatically induced autoregulatory disturbances and their modulation by hypothermic intervention, examining these phenomena in two different models of TBI. Adult rats were subjected to either impact acceleration injury (IAI) or lateral fluid percussion injury (LFPI) followed by the insertion of cranial windows to assess the pial arteriolar cerebral autoregulatory vascular response to the post-traumatic induction of sequential reductions of arterial blood pressure. The potential for continued pial vasodilation in response to declining blood pressure was directly measured post-injury and compared with that in injured groups subjected to 33° C of hypothermia of 1-2 h duration initiated 1 h post-injury. We observed that the TBI resulted in either impaired or abolished cerebral vascular dilation in response to the sequential declines in blood pressure. Following IAI there was a 50% reduction in the vasculature's ability to dilate in response to the induced hypotension. In contrast, following LFPI, the vascular response to hypotension was abolished both ipsilateral and contralateral to the LFPI. In animals sustaining IAI, the use of 1 h post-traumatic hypothermia preserved vascular dilation in response to declines in blood pressure in contrast to the LFPI in which the use of the same strategy afforded no improvement. However, with LFPI, the use of 2 h of hypothermia provided partial vascular protection. These results clearly illustrate that TBI can alter the cerebral autoregulatory vascular response to sequentially induced hypotensive insult, whereas the use of post-traumatic hypothermia provides benefit. Collectively, these studies also demonstrate that different animal models of TBI can evoke different biological responses to injury.
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Affiliation(s)
- Motoki Fujita
- Department of Anatomy and Neurobiology, Virginia Commonwealth University Medical Center, Richmond, Virginia 23298, USA
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23
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Bramlett HM, Dietrich WD. THE EFFECTS OF POSTTRAUMATIC HYPOTHERMIA ON DIFFUSE AXONAL INJURY FOLLOWING PARASAGGITAL FLUID PERCUSSION BRAIN INJURY IN RATS. Ther Hypothermia Temp Manag 2012; 2:14-23. [PMID: 23420536 DOI: 10.1089/ther.2012.0002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Previous investigations have demonstrated the beneficial effects of mild hypothermia following different types of traumatic brain injury (TBI). In some models, early cooling following TBI has been shown to reduce the frequency of axonal damage, a major consequence of head injury. The purpose of this study was to evaluate the effects of posttraumatic hypothermia in a model that has been shown to be sensitive to temperature manipulations in the early injury setting. Animals underwent moderate parasagittal fluid percussion (FP) brain injury and were then either randomized into normothermic or hypothermic groups. In the hypothermic groups, brain temperature was reduced to either 30 or 33°C 5 minutes after trauma and maintained for a three hour period. Normothermic or sham-operated animals were held under normal temperature conditions. At three days after TBI, animals were perfusion-fixed for quantitative assessment of β-APP immunohistochemistry and silver staining. Traumatic injury led to a significant increase in the frequency of β-APP immunoreactive profiles both within the corpus callosum, external capsule, as well as internal capsule. While early cooling revealed a trend for protection, no significant differences were shown between normothermic and hypothermic animals in terms of the frequency of injured axons at 3 days posttrauma. These results emphasize that axonal pathology is a major consequence of brain injury using this particular model. It is concluded that longer periods of posttraumatic hypothermia may be required to chronically protect axon populations undergoing progressive injury.
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Affiliation(s)
- Helen M Bramlett
- The Miami Project to Cure Paralysis, The Department of Neurological Surgery University of Miami Miller School of Medicine Miami, Florida 33136
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Yan EB, Hellewell SC, Bellander BM, Agyapomaa DA, Morganti-Kossmann MC. Post-traumatic hypoxia exacerbates neurological deficit, neuroinflammation and cerebral metabolism in rats with diffuse traumatic brain injury. J Neuroinflammation 2011; 8:147. [PMID: 22034986 PMCID: PMC3215944 DOI: 10.1186/1742-2094-8-147] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2011] [Accepted: 10/28/2011] [Indexed: 11/29/2022] Open
Abstract
Background The combination of diffuse brain injury with a hypoxic insult is associated with poor outcomes in patients with traumatic brain injury. In this study, we investigated the impact of post-traumatic hypoxia in amplifying secondary brain damage using a rat model of diffuse traumatic axonal injury (TAI). Rats were examined for behavioral and sensorimotor deficits, increased brain production of inflammatory cytokines, formation of cerebral edema, changes in brain metabolism and enlargement of the lateral ventricles. Methods Adult male Sprague-Dawley rats were subjected to diffuse TAI using the Marmarou impact-acceleration model. Subsequently, rats underwent a 30-minute period of hypoxic (12% O2/88% N2) or normoxic (22% O2/78% N2) ventilation. Hypoxia-only and sham surgery groups (without TAI) received 30 minutes of hypoxic or normoxic ventilation, respectively. The parameters examined included: 1) behavioural and sensorimotor deficit using the Rotarod, beam walk and adhesive tape removal tests, and voluntary open field exploration behavior; 2) formation of cerebral edema by the wet-dry tissue weight ratio method; 3) enlargement of the lateral ventricles; 4) production of inflammatory cytokines; and 5) real-time brain metabolite changes as assessed by microdialysis technique. Results TAI rats showed significant deficits in sensorimotor function, and developed substantial edema and ventricular enlargement when compared to shams. The additional hypoxic insult significantly exacerbated behavioural deficits and the cortical production of the pro-inflammatory cytokines IL-6, IL-1β and TNF but did not further enhance edema. TAI and particularly TAI+Hx rats experienced a substantial metabolic depression with respect to glucose, lactate, and glutamate levels. Conclusion Altogether, aggravated behavioural deficits observed in rats with diffuse TAI combined with hypoxia may be induced by enhanced neuroinflammation, and a prolonged period of metabolic dysfunction.
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Affiliation(s)
- Edwin B Yan
- National Trauma Research Institute, The Alfred Hospital, 89 Commercial Road, Melbourne 3004, Australia
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25
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Marklund N, Hillered L. Animal modelling of traumatic brain injury in preclinical drug development: where do we go from here? Br J Pharmacol 2011; 164:1207-29. [PMID: 21175576 PMCID: PMC3229758 DOI: 10.1111/j.1476-5381.2010.01163.x] [Citation(s) in RCA: 178] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2010] [Revised: 12/02/2010] [Accepted: 12/06/2010] [Indexed: 11/26/2022] Open
Abstract
Traumatic brain injury (TBI) is the leading cause of death and disability in young adults. Survivors of TBI frequently suffer from long-term personality changes and deficits in cognitive and motor performance, urgently calling for novel pharmacological treatment options. To date, all clinical trials evaluating neuroprotective compounds have failed in demonstrating clinical efficacy in cohorts of severely injured TBI patients. The purpose of the present review is to describe the utility of animal models of TBI for preclinical evaluation of pharmacological compounds. No single animal model can adequately mimic all aspects of human TBI owing to the heterogeneity of clinical TBI. To successfully develop compounds for clinical TBI, a thorough evaluation in several TBI models and injury severities is crucial. Additionally, brain pharmacokinetics and the time window must be carefully evaluated. Although the search for a single-compound, 'silver bullet' therapy is ongoing, a combination of drugs targeting various aspects of neuroprotection, neuroinflammation and regeneration may be needed. In summary, finding drugs and prove clinical efficacy in TBI is a major challenge ahead for the research community and the drug industry. For a successful translation of basic science knowledge to the clinic to occur we believe that a further refinement of animal models and functional outcome methods is important. In the clinical setting, improved patient classification, more homogenous patient cohorts in clinical trials, standardized treatment strategies, improved central nervous system drug delivery systems and monitoring of target drug levels and drug effects is warranted.
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Affiliation(s)
- Niklas Marklund
- Department of Neuroscience, Neurosurgery, Uppsala University, Uppsala University Hospital, Uppsala, Sweden.
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Wang J, Hamm RJ, Povlishock JT. Traumatic axonal injury in the optic nerve: evidence for axonal swelling, disconnection, dieback, and reorganization. J Neurotrauma 2011; 28:1185-98. [PMID: 21506725 DOI: 10.1089/neu.2011.1756] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Traumatic axonal injury (TAI) is a major feature of traumatic brain injury (TBI) and is associated with much of its morbidity. To date, significant insight has been gained into the initiating pathogenesis of TAI. However, the nature of TAI within the injured brain precludes the consistent evaluation of its specific anterograde and retrograde sequelae. To overcome this limitation, we used the relatively organized optic nerve in a central fluid percussion injury (cFPI) model. To improve the visualization of TAI, we utilized mice expressing yellow fluorescent protein (YFP) in their visual pathways. Through this approach, we consistently generated TAI in the optic nerve and qualitatively and quantitatively evaluated its progression over a 48-h period in YFP axons via confocal microscopy and electron microscopy. In this model, delayed axonal swelling with subsequent disconnection were the norm, together with the fact that once disconnected, both the proximal and distal axonal segments revealed significant dieback, with the proximal swellings showing regression and reorganization, while the distal swellings persisted, although showing signs of impending degeneration. When antibodies targeting the C-terminus of amyloid precursor protein (APP), a routine marker of TAI were employed, they mapped exclusively to the proximal axonal segments without distal targeting, regardless of the survival time. Concomitant with this evolving axonal pathology, focal YFP fluorescence quenching occurred and mapped precisely to immunoreactive loci positive for Texas-Red-conjugated-IgG, indicating that blood-brain barrier disruption and its attendant edema contributed to this phenomenon. This was confirmed through the use of antibodies targeting endogenous YFP, which demonstrated the retention of intact immunoreactive axons despite YFP fluorescence quenching. Collectively, the results of this study within the injured optic nerve provide unprecedented insight into the evolving pathobiology associated with TAI.
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Affiliation(s)
- Jiaqiong Wang
- Department of Anatomy and Neurobiology, Virginia Commonwealth University Medical Center, Richmond, VA 23298, USA
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Oda Y, Gao G, Wei EP, Povlishock JT. Combinational therapy using hypothermia and the immunophilin ligand FK506 to target altered pial arteriolar reactivity, axonal damage, and blood-brain barrier dysfunction after traumatic brain injury in rat. J Cereb Blood Flow Metab 2011; 31:1143-54. [PMID: 21157473 PMCID: PMC3070975 DOI: 10.1038/jcbfm.2010.208] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This study evaluated the utility of combinational therapy, coupling delayed posttraumatic hypothermia with delayed FK506 administration, on altered cerebral vascular reactivity, axonal injury, and blood-brain barrier (BBB) disruption seen following traumatic brain injury (TBI). Animals were injured, subjected to various combinations of hypothermic/FK506 intervention, and equipped with cranial windows to assess pial vascular reactivity to acetylcholine. Animals were then processed with antibodies to the amyloid precursor protein and immunoglobulin G to assess axonal injury and BBB disruption, respectively. Animals were assigned to five groups: (1) sham injury plus delayed FK506, (2) TBI, (3) TBI plus delayed hypothermia, (4) TBI plus delayed FK506, and (5) TBI plus delayed hypothermia with FK506. Sham injury plus FK506 had no impact on vascular reactivity, axonal injury, or BBB disruption. Traumatic brain injury induced dramatic axonal injury and altered pial vascular reactivity, while triggering local BBB disruption. Delayed hypothermia or FK506 after TBI provided limited protection. However, TBI with combinational therapy achieved significantly enhanced vascular and axonal protection, with no BBB protection. This study shows the benefits of combinational therapy, using posttraumatic hypothermia with FK506 to attenuate important features of TBI. This suggests that hypothermia not only protects but also extends the therapeutic window for improved FK506 efficacy.
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Affiliation(s)
- Yasutaka Oda
- Department of Anatomy and Neurobiology, Virginia Commonwealth University Medical Center, Richmond, Virginia 23298, USA
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Hellewell SC, Yan EB, Agyapomaa DA, Bye N, Morganti-Kossmann MC. Post-Traumatic Hypoxia Exacerbates Brain Tissue Damage: Analysis of Axonal Injury and Glial Responses. J Neurotrauma 2010; 27:1997-2010. [DOI: 10.1089/neu.2009.1245] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Sarah C. Hellewell
- National Trauma Research Institute, The Alfred Hospital, Melbourne, Victoria, Australia
- Department of Medicine, Monash University, Melbourne, Victoria, Australia
| | - Edwin B. Yan
- National Trauma Research Institute, The Alfred Hospital, Melbourne, Victoria, Australia
- Department of Medicine, Monash University, Melbourne, Victoria, Australia
| | - Doreen A. Agyapomaa
- National Trauma Research Institute, The Alfred Hospital, Melbourne, Victoria, Australia
- Department of Medicine, Monash University, Melbourne, Victoria, Australia
| | - Nicole Bye
- National Trauma Research Institute, The Alfred Hospital, Melbourne, Victoria, Australia
- Department of Medicine, Monash University, Melbourne, Victoria, Australia
| | - M. Cristina Morganti-Kossmann
- National Trauma Research Institute, The Alfred Hospital, Melbourne, Victoria, Australia
- Department of Medicine, Monash University, Melbourne, Victoria, Australia
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Atkins CM, Truettner JS, Lotocki G, Sanchez-Molano J, Kang Y, Alonso OF, Sick TJ, Dietrich WD, Bramlett HM. Post-traumatic seizure susceptibility is attenuated by hypothermia therapy. Eur J Neurosci 2010; 32:1912-20. [PMID: 21044182 DOI: 10.1111/j.1460-9568.2010.07467.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Traumatic brain injury (TBI) is a major risk factor for the subsequent development of epilepsy. Currently, chronic seizures after brain injury are often poorly controlled by available antiepileptic drugs. Hypothermia treatment, a modest reduction in brain temperature, reduces inflammation, activates pro-survival signaling pathways, and improves cognitive outcome after TBI. Given the well-known effect of therapeutic hypothermia to ameliorate pathological changes in the brain after TBI, we hypothesized that hypothermia therapy may attenuate the development of post-traumatic epilepsy and some of the pathomechanisms that underlie seizure formation. To test this hypothesis, adult male Sprague Dawley rats received moderate parasagittal fluid-percussion brain injury, and were then maintained at normothermic or moderate hypothermic temperatures for 4 h. At 12 weeks after recovery, seizure susceptibility was assessed by challenging the animals with pentylenetetrazole, a GABA(A) receptor antagonist. Pentylenetetrazole elicited a significant increase in seizure frequency in TBI normothermic animals as compared with sham surgery animals and this was significantly reduced in TBI hypothermic animals. Early hypothermia treatment did not rescue chronic dentate hilar neuronal loss nor did it improve loss of doublecortin-labeled cells in the dentate gyrus post-seizures. However, mossy fiber sprouting was significantly attenuated by hypothermia therapy. These findings demonstrate that reductions in seizure susceptibility after TBI are improved with post-traumatic hypothermia and provide a new therapeutic avenue for the treatment of post-traumatic epilepsy.
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Affiliation(s)
- Coleen M Atkins
- Department of Neurological Surgery, University of Miami Miller School of Medicine, Miami, FL 33136, USA
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