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Ritzel RM, He J, Li Y, Cao T, Khan N, Shim B, Sabirzhanov B, Aubrecht T, Stoica BA, Faden AI, Wu LJ, Wu J. Proton extrusion during oxidative burst in microglia exacerbates pathological acidosis following traumatic brain injury. Glia 2020; 69:746-764. [PMID: 33090575 PMCID: PMC7819364 DOI: 10.1002/glia.23926] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Revised: 10/01/2020] [Accepted: 10/07/2020] [Indexed: 01/02/2023]
Abstract
Acidosis is among the least studied secondary injury mechanisms associated with neurotrauma. Acute decreases in brain pH correlate with poor long‐term outcome in patients with traumatic brain injury (TBI), however, the temporal dynamics and underlying mechanisms are unclear. As key drivers of neuroinflammation, we hypothesized that microglia directly regulate acidosis after TBI, and thereby, worsen neurological outcomes. Using a controlled cortical impact model in adult male mice we demonstrate that intracellular pH in microglia and extracellular pH surrounding the lesion site are significantly reduced for weeks after injury. Microglia proliferation and production of reactive oxygen species (ROS) were also increased during the first week, mirroring the increase in extracellular ROS levels seen around the lesion site. Microglia depletion by a colony stimulating factor 1 receptor (CSF1R) inhibitor, PLX5622, markedly decreased extracellular acidosis, ROS production, and inflammation in the brain after injury. Mechanistically, we identified that the voltage‐gated proton channel Hv1 promotes oxidative burst activity and acid extrusion in microglia. Compared to wildtype controls, microglia lacking Hv1 showed reduced ability to generate ROS and extrude protons. Importantly, Hv1‐deficient mice exhibited reduced pathological acidosis and inflammation after TBI, leading to long‐term neuroprotection and functional recovery. Our data therefore establish the microglial Hv1 proton channel as an important link that integrates inflammation and acidosis within the injury microenvironment during head injury.
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Affiliation(s)
- Rodney M Ritzel
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Junyun He
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Yun Li
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Tuoxin Cao
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Niaz Khan
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Bosung Shim
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Boris Sabirzhanov
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Taryn Aubrecht
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Bogdan A Stoica
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, Maryland, USA
| | - Alan I Faden
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, Maryland, USA.,University of Maryland Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Maryland, USA
| | - Long-Jun Wu
- Department of Neurology, Mayo Clinic, Rochester, Minnesota, USA
| | - Junfang Wu
- Department of Anesthesiology and Center for Shock, Trauma and Anesthesiology Research (STAR), University of Maryland School of Medicine, Baltimore, Maryland, USA.,University of Maryland Center to Advance Chronic Pain Research, University of Maryland, Baltimore, Maryland, USA
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Sabirzhanov B, Faden AI, Aubrecht T, Henry R, Glaser E, Stoica BA. MicroRNA-711-Induced Downregulation of Angiopoietin-1 Mediates Neuronal Cell Death. J Neurotrauma 2018; 35:2462-2481. [PMID: 29774773 DOI: 10.1089/neu.2017.5572] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Angiopoietin-1 (Ang-1) is a well-known endothelial growth factor, but its effects on neurons have yet to be elucidated. We show that Ang-1 is rapidly downregulated in the injured brain after controlled cortical impact (CCI), a mouse experimental traumatic brain injury (TBI) model and in etoposide-induced neuronal apoptosis in vitro. Ang-1 treatment inhibits etoposide-induced upregulation of proapoptotic B-cell lymphoma 2 (Bcl-2) family members Noxa, p53 upregulated modulator of apoptosis (Puma), Bcl-2 interacting mediator of cell death (Bim), and Bcl-2-associated X protein (Bax); reduces markers of caspase-dependent (cytochrome c release/caspase activation) and caspase-independent (apoptosis-inducing factor release) pathways; and limits neuronal cell death. Ang-1 treatment phosphorylates receptors Tunica interna endothelial cell kinase 2 (Tie2), and β1-integrin and limits the etoposide-induced decrease in protein kinase B (Akt) activity. Blocking Tie2 and β1-integrin signaling reduces Ang-1 neuroprotective effects. After both TBI and etoposide treatment microRNA (miR)-711 are upregulated, consistent with its putative role as a negative regulator of Ang-1. We show that miR-711 directly targets the Ang-1 messenger RNA (mRNA), decreasing Ang-1 expression. Increased levels of miR-711 and Ang-1 mRNA are found in the RNA-induced silencing complex complex site of miR-mediated degradation of target mRNAs after etoposide treatment and the miR-711mimic downregulates Ang-1. Administration of miR-711 inhibitor elevates Ang-1 after TBI whereas Ang-1 administration increases Akt activation; reduces Puma, Noxa, Bim, and Bax levels; and attenuates caspase-dependent and -independent neuronal apoptosis 24 h after TBI. Ang-1 also attenuates neuronal degeneration, increases gene expression of molecules that maintain blood-brain barrier integrity, and reduces post-traumatic lesion volume/edema 24 h after TBI. Although we only observed short-term neuroprotective effects after Ang-1 administration, miR-711-dependent downregulation of Ang-1, followed by Akt pathway inhibition, may play a role in neuronal cell death after neuronal injury in vitro and after experimental TBI.
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Affiliation(s)
- Boris Sabirzhanov
- Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland , School of Medicine, Baltimore, Maryland
| | - Alan I Faden
- Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland , School of Medicine, Baltimore, Maryland
| | - Taryn Aubrecht
- Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland , School of Medicine, Baltimore, Maryland
| | - Rebecca Henry
- Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland , School of Medicine, Baltimore, Maryland
| | - Ethan Glaser
- Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland , School of Medicine, Baltimore, Maryland
| | - Bogdan A Stoica
- Department of Anesthesiology and Center for Shock, Trauma, and Anesthesiology Research (STAR), University of Maryland , School of Medicine, Baltimore, Maryland
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Hanscom M, Aubrecht T, Loane DJ, Faden AI, Shea‐Donohue T. Colitis‐Induced Neurobehavioral Deficits Following Chronic Brain Injury. FASEB J 2018. [DOI: 10.1096/fasebj.2018.32.1_supplement.921.8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Marie Hanscom
- Department of Anesthesiology and ShockTrauma and Anesthesiology Research (STAR) CenterUniversity of Maryland School of MedicineBaltimoreMD
| | - Taryn Aubrecht
- Department of Anesthesiology and ShockTrauma and Anesthesiology Research (STAR) CenterUniversity of Maryland School of MedicineBaltimoreMD
| | - David J. Loane
- Department of Anesthesiology and ShockTrauma and Anesthesiology Research (STAR) CenterUniversity of Maryland School of MedicineBaltimoreMD
| | - Alan I. Faden
- Department of Anesthesiology and ShockTrauma and Anesthesiology Research (STAR) CenterUniversity of Maryland School of MedicineBaltimoreMD
| | - Terez Shea‐Donohue
- Department of Radiation OncologyUniversity of Maryland School of MedicineBaltimoreMD
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