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Giannetto MJ, Gomolka RS, Gahn-Martinez D, Newbold EJ, Bork PAR, Chang E, Gresser M, Thompson T, Mori Y, Nedergaard M. Glymphatic fluid transport is suppressed by the aquaporin-4 inhibitor AER-271. Glia 2024; 72:982-998. [PMID: 38363040 PMCID: PMC11203403 DOI: 10.1002/glia.24515] [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] [Received: 06/05/2023] [Revised: 01/29/2024] [Accepted: 02/05/2024] [Indexed: 02/17/2024]
Abstract
The glymphatic system transports cerebrospinal fluid (CSF) into the brain via arterial perivascular spaces and removes interstitial fluid from the brain along perivenous spaces and white matter tracts. This directional fluid flow supports the clearance of metabolic wastes produced by the brain. Glymphatic fluid transport is facilitated by aquaporin-4 (AQP4) water channels, which are enriched in the astrocytic vascular endfeet comprising the outer boundary of the perivascular space. Yet, prior studies of AQP4 function have relied on genetic models, or correlated altered AQP4 expression with glymphatic flow in disease states. Herein, we sought to pharmacologically manipulate AQP4 function with the inhibitor AER-271 to assess the contribution of AQP4 to glymphatic fluid transport in mouse brain. Administration of AER-271 inhibited glymphatic influx as measured by CSF tracer infused into the cisterna magna and inhibited increases in the interstitial fluid volume as measured by diffusion-weighted MRI. Furthermore, AER-271 inhibited glymphatic efflux as assessed by an in vivo clearance assay. Importantly, AER-271 did not affect AQP4 localization to the astrocytic endfeet, nor have any effect in AQP4 deficient mice. Since acute pharmacological inhibition of AQP4 directly decreased glymphatic flow in wild-type but not in AQP4 deficient mice, we foresee AER-271 as a new tool for manipulation of the glymphatic system in rodent brain.
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Affiliation(s)
- Michael J. Giannetto
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA
- Department of Neuroscience, University of Rochester Medical Center, Rochester, NY, USA
| | - Ryszard S. Gomolka
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Daniel Gahn-Martinez
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA
| | - Evan J. Newbold
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA
- Department of Neuroscience, University of Rochester Medical Center, Rochester, NY, USA
| | - Peter A. R. Bork
- Department of Physics, Technical University of Denmark, Richard Petersens Plads, 2800 Lyngby, Denmark
| | - Ethan Chang
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA
| | - Michael Gresser
- Aeromics Inc., 470 James Street Suite 007, New Haven, CT 06513
| | - Trevor Thompson
- Aeromics Inc., 470 James Street Suite 007, New Haven, CT 06513
| | - Yuki Mori
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, NY, USA
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, 2200 Copenhagen, Denmark
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Bordoni L, Thoren AE, Gutiérrez‐Jiménez E, Åbjørsbråten KS, Bjørnstad DM, Tang W, Stern M, Østergaard L, Nagelhus EA, Frische S, Ottersen OP, Enger R. Deletion of aquaporin-4 improves capillary blood flow distribution in brain edema. Glia 2023; 71:2559-2572. [PMID: 37439315 PMCID: PMC10952478 DOI: 10.1002/glia.24439] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 06/22/2023] [Accepted: 06/26/2023] [Indexed: 07/14/2023]
Abstract
Brain edema is a feared complication to disorders and insults affecting the brain. It can be fatal if the increase in intracranial pressure is sufficiently large to cause brain herniation. Moreover, accruing evidence suggests that even slight elevations of intracranial pressure have adverse effects, for instance on brain perfusion. The water channel aquaporin-4 (AQP4), densely expressed in perivascular astrocytic endfeet, plays a key role in brain edema formation. Using two-photon microscopy, we have studied AQP4-mediated swelling of astrocytes affects capillary blood flow and intracranial pressure (ICP) in unanesthetized mice using a mild brain edema model. We found improved regulation of capillary blood flow in mice devoid of AQP4, independently of the severity of ICP increase. Furthermore, we found brisk AQP4-dependent astrocytic Ca2+ signals in perivascular endfeet during edema that may play a role in the perturbed capillary blood flow dynamics. The study suggests that astrocytic endfoot swelling and pathological signaling disrupts microvascular flow regulation during brain edema formation.
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Affiliation(s)
- Luca Bordoni
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
- Department of BiomedicineAarhus UniversityAarhusDenmark
| | - Anna E. Thoren
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
| | - Eugenio Gutiérrez‐Jiménez
- Center of Functionally Integrative Neuroscience (CFIN), Department of Clinical MedicineAarhus UniversityAarhusDenmark
| | - Knut S. Åbjørsbråten
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
| | - Daniel M. Bjørnstad
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
| | - Wannan Tang
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
- Department of Clinical and Molecular MedicineNorwegian University of Science and TechnologyTrondheimNorway
- Department of Neurology, NeuroclinicSt. Olavs HospitalTrondheimNorway
| | - Mette Stern
- Department of BiomedicineAarhus UniversityAarhusDenmark
| | - Leif Østergaard
- Center of Functionally Integrative Neuroscience (CFIN), Department of Clinical MedicineAarhus UniversityAarhusDenmark
- Department of NeuroradiologyAarhus University HospitalAarhusDenmark
| | - Erlend A. Nagelhus
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
| | | | - Ole P. Ottersen
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
| | - Rune Enger
- GliaLab and Letten Centre, Division of Anatomy, Department of Molecular Medicine, Institute of Basic Medical SciencesUniversity of OsloOsloNorway
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Bordoni L, Li B, Kura S, Boas DA, Sakadžić S, Østergaard L, Frische S, Gutiérrez-Jiménez E. Quantification of Capillary Perfusion in an Animal Model of Acute Intracranial Hypertension. J Neurotrauma 2020; 38:446-454. [PMID: 32998634 DOI: 10.1089/neu.2019.6901] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Intracranial hypertension (IH) is a common feature of many pathologies, including brain edema. In the brain, the extended network of capillaries ensures blood flow to meet local metabolic demands. Capillary circulation may be severely affected by IH, but no studies have quantified the effect of intracranial pressure (ICP) and cerebral perfusion pressure (CPP) on capillary perfusion during the development of brain edema. We used optical coherence tomography angiography to quantify relative changes of fractional perfused volume (FPV) in cortical capillaries and simultaneously monitored ICP and blood pressure (BP) in anesthetized male C57Bl/6NTac mice during development of brain edema induced by water intoxication (WI) within 30 min. WI induced severe IH and brain herniation. ICP and CPP reached 90.2 mm Hg and 38.4 mm Hg, respectively. FPV was significantly affected already at normal ICP (ICP <15 mm Hg, slope ≈ -1.46, p < 0.001) and, at the onset of IH (ICP = 20-22 mm Hg), FPV was 17.9 ± 13.3% lower than baseline. A decreasing trend was observed until the ICP peak (Δ%FPV = -43.6 ± 19.2%). In the ICP range of 7-42 mm Hg, relative changes in FPV were significantly correlated with ICP, BP, and CPP (p < 0.001), with ICP and CPP being the best predictors. In conclusion, elevated ICP induces a gradual collapse of the cerebral microvasculature, which is initiated before the clinical threshold of IH. In summary, the estimate of capillary perfusion might be essential in patients with IH to assess the state of the brain microcirculation and to improve the availability of oxygen and nutrients to the brain.
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Affiliation(s)
- Luca Bordoni
- Institute of Biomedicine, Aarhus University, Aarhus C, Denmark
| | - Baoqiang Li
- Brain Cognition and Brain Disease Institute, Chinese Academy of Sciences, Shenzhen, China.,Shenzhen-Hong Kong Institute of Brain Science, Shenzhen Fundamental Research Institutions, Shenzhen, China
| | - Sreekanth Kura
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA
| | - David A Boas
- Department of Biomedical Engineering, Boston University, Boston, Massachusetts, USA.,Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
| | - Sava Sakadžić
- Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Charlestown, Massachusetts, USA
| | - Leif Østergaard
- Department of Clinical Medicine, Aarhus University, Aarhus C, Denmark.,Department of Neuroradiology, Aarhus University Hospital, Aarhus C, Denmark
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