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Castro-Arnau J, Chauvigné F, Toft-Bertelsen TL, Finn RN, MacAulay N, Cerdà J. Aqp4a and Trpv4 mediate regulatory cell volume increase for swimming maintenance of marine fish spermatozoa. Cell Mol Life Sci 2024; 81:285. [PMID: 38969941 DOI: 10.1007/s00018-024-05341-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2024] [Revised: 06/19/2024] [Accepted: 06/28/2024] [Indexed: 07/07/2024]
Abstract
Volume regulation is essential for cell homeostasis and physiological function. Amongst the sensory molecules that have been associated with volume regulation is the transient receptor potential vanilloid 4 (TRPV4), which is a non-selective cation channel that in conjunction with aquaporins, typically controls regulatory volume decrease (RVD). Here we show that the interaction between orthologous AQP4 (Aqp4a) and TRPV4 (Trpv4) is important for regulatory volume increase (RVI) in post-activated marine fish spermatozoa under high osmotic stress. Based upon electrophysiological, volumetric, and in vivo and ex vivo functional experiments using the pharmacological and immunological inhibition of Aqp4a and Trpv4 our model suggests that upon ejaculation and exposure to the hypertonic seawater, spermatozoon shrinkage is initially mediated by water efflux through Aqp1aa in the flagellar tail. The shrinkage results in an increase in intracellular Ca2+ concentration, and the activation of sperm motility and a Na+/K+/2Cl- (NKCC1) cotransporter. The activity of NKCC1 is required for the initiation of cell swelling, which secondarily activates the Aqp4a-Trpv4 complex to facilitate the influx of water via Aqp4a-M43 and Ca2+ via Trpv4 and L-type channels for the mediation of RVI. The inhibitory experiments show that blocking of each of these events prevents either shrinkage or RVI. Our data thus reveal that post-activated marine fish spermatozoa are capable of initiating RVI under a high hypertonic stress, which is essential for the maintenance of sperm motility.
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Affiliation(s)
- Júlia Castro-Arnau
- Institute of Marine Sciences, Spanish National Research Council (CSIC), Barcelona, 08003, Spain
- Institute of Biotechnology and Biomedicine (IBB), Universitat Autònoma de Barcelona, Bellaterra (Barcelona), 08193, Spain
- Department of Cell Biology & Physiology, Washington University in St. Louis School of Medicine, St. Louis, MO, 63110, USA
| | - François Chauvigné
- Institute of Marine Sciences, Spanish National Research Council (CSIC), Barcelona, 08003, Spain
- Institute of Biotechnology and Biomedicine (IBB), Universitat Autònoma de Barcelona, Bellaterra (Barcelona), 08193, Spain
| | | | - Roderick Nigel Finn
- Institute of Biotechnology and Biomedicine (IBB), Universitat Autònoma de Barcelona, Bellaterra (Barcelona), 08193, Spain
- Department of Biological Sciences, University of Bergen, Bergen, 5020, Norway
| | - Nanna MacAulay
- Department of Neuroscience, University of Copenhagen, Copenhagen N, 2200, Denmark
| | - Joan Cerdà
- Institute of Marine Sciences, Spanish National Research Council (CSIC), Barcelona, 08003, Spain.
- Institute of Biotechnology and Biomedicine (IBB), Universitat Autònoma de Barcelona, Bellaterra (Barcelona), 08193, Spain.
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Chen Z, Lai JHC, Xu J, Zhang H, Huang J, Chan KWY. The effect of aquaporin-4 inhibition on cerebrospinal fluid-tissue water exchange in mouse brain detected by magnetization transfer indirect spin labeling MRI. NMR IN BIOMEDICINE 2024; 37:e5093. [PMID: 38163739 DOI: 10.1002/nbm.5093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 11/19/2023] [Accepted: 11/27/2023] [Indexed: 01/03/2024]
Abstract
The fluid transport of cerebrospinal fluid (CSF) and interstitial fluid in surrounding tissues plays an important role in the drainage pathway that facilitates waste clearance from the brain. This pathway is known as the glymphatic or perivascular system, and its functions are dependent on aquaporin-4 (AQP4). Recently, magnetization transfer indirect spin labeling (MISL) magnetic resonance imaging (MRI) has been proposed as a noninvasive and noncontrast-enhanced method for detecting water exchange between CSF and brain tissue. In this study, we first optimized the MISL sequence at preclinical 3 T MRI, and then studied the correlation of MISL in CSF with magnetization transfer (MT) in brain tissue, as well as the altered water exchange under AQP4 inhibition, using C57BL/6 mice. Results showed a strong correlation of MISL signal with MT signal. With the AQP4 inhibitor, we observed a significant decrease in MISL value (P < 0.05), suggesting that the hampered AQP4 activity led to decreased water exchange between CSF and brain tissue or the impairment of the glymphatic function. Overall, our findings demonstrate the potential application of MISL in assessing brain water exchange at 3 T MRI and its potential clinical translation.
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Affiliation(s)
- Zilin Chen
- Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China
| | - Joseph H C Lai
- Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China
| | - Jiadi Xu
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, Maryland, USA
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Hao Zhang
- Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China
| | - Jianpan Huang
- Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong, China
| | - Kannie W Y Chan
- Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
- Hong Kong Centre for Cerebro-Cardiovascular Health Engineering (COCHE), Hong Kong, China
- Tung Biomedical Sciences Centre (TBSC), Hong Kong, China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, China
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3
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Hladky SB, Barrand MA. Alterations in brain fluid physiology during the early stages of development of ischaemic oedema. Fluids Barriers CNS 2024; 21:51. [PMID: 38858667 PMCID: PMC11163777 DOI: 10.1186/s12987-024-00534-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Accepted: 03/22/2024] [Indexed: 06/12/2024] Open
Abstract
Oedema occurs when higher than normal amounts of solutes and water accumulate in tissues. In brain parenchymal tissue, vasogenic oedema arises from changes in blood-brain barrier permeability, e.g. in peritumoral oedema. Cytotoxic oedema arises from excess accumulation of solutes within cells, e.g. ischaemic oedema following stroke. This type of oedema is initiated when blood flow in the affected core region falls sufficiently to deprive brain cells of the ATP needed to maintain ion gradients. As a consequence, there is: depolarization of neurons; neural uptake of Na+ and Cl- and loss of K+; neuronal swelling; astrocytic uptake of Na+, K+ and anions; swelling of astrocytes; and reduction in ISF volume by fluid uptake into neurons and astrocytes. There is increased parenchymal solute content due to metabolic osmolyte production and solute influx from CSF and blood. The greatly increased [K+]isf triggers spreading depolarizations into the surrounding penumbra increasing metabolic load leading to increased size of the ischaemic core. Water enters the parenchyma primarily from blood, some passing into astrocyte endfeet via AQP4. In the medium term, e.g. after three hours, NaCl permeability and swelling rate increase with partial opening of tight junctions between blood-brain barrier endothelial cells and opening of SUR1-TPRM4 channels. Swelling is then driven by a Donnan-like effect. Longer term, there is gross failure of the blood-brain barrier. Oedema resolution is slower than its formation. Fluids without colloid, e.g. infused mock CSF, can be reabsorbed across the blood-brain barrier by a Starling-like mechanism whereas infused serum with its colloids must be removed by even slower extravascular means. Large scale oedema can increase intracranial pressure (ICP) sufficiently to cause fatal brain herniation. The potentially lethal increase in ICP can be avoided by craniectomy or by aspiration of the osmotically active infarcted region. However, the only satisfactory treatment resulting in retention of function is restoration of blood flow, providing this can be achieved relatively quickly. One important objective of current research is to find treatments that increase the time during which reperfusion is successful. Questions still to be resolved are discussed.
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Affiliation(s)
- Stephen B Hladky
- Department of Pharmacology, Tennis Court Rd., Cambridge, CB2 1PD, UK.
| | - Margery A Barrand
- Department of Pharmacology, Tennis Court Rd., Cambridge, CB2 1PD, UK
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Hermanova Z, Valihrach L, Kriska J, Maheta M, Tureckova J, Kubista M, Anderova M. The deletion of AQP4 and TRPV4 affects astrocyte swelling/volume recovery in response to ischemia-mimicking pathologies. Front Cell Neurosci 2024; 18:1393751. [PMID: 38818517 PMCID: PMC11138210 DOI: 10.3389/fncel.2024.1393751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Accepted: 05/01/2024] [Indexed: 06/01/2024] Open
Abstract
Introduction Astrocytic Transient receptor potential vanilloid 4 (TRPV4) channels, together with Aquaporin 4 (AQP4), are suspected to be the key players in cellular volume regulation, and therefore may affect the development and severity of cerebral edema during ischemia. In this study, we examined astrocytic swelling/volume recovery in mice with TRPV4 and/or AQP4 deletion in response to in vitro ischemic conditions, to determine how the deletion of these channels can affect the development of cerebral edema. Methods We used three models of ischemia-related pathological conditions: hypoosmotic stress, hyperkalemia, and oxygenglucose deprivation (OGD), and observed their effect on astrocyte volume changes in acute brain slices of Aqp4-/-, Trpv4-/- and double knockouts. In addition, we employed single-cell RT-qPCR to assess the effect of TRPV4 and AQP4 deletion on the expression of other ion channels and transporters involved in the homeostatic functioning of astrocytes. Results Quantification of astrocyte volume changes during OGD revealed that the deletion of AQP4 reduces astrocyte swelling, while simultaneous deletion of both AQP4 and TRPV4 leads to a disruption of astrocyte volume recovery during the subsequent washout. Of note, astrocyte exposure to hypoosmotic stress or hyperkalemia revealed no differences in astrocyte swelling in the absence of AQP4, TRPV4, or both channels. Moreover, under ischemia-mimicking conditions, we identified two distinct subpopulations of astrocytes with low and high volumetric responses (LRA and HRA), and their analyses revealed that mainly HRA are affected by the deletion of AQP4, TRPV4, or both channels. Furthermore, gene expression analysis revealed reduced expression of the ion transporters KCC1 and ClC2 as well as the receptors GABAB and NMDA in Trpv4-/- mice. The deletion of AQP4 instead caused reduced expression of the serine/cysteine peptidase inhibitor Serpina3n. Discussion Thus, we showed that in AQP4 or TRPV4 knockouts, not only the specific function of these channels is affected, but also the expression of other proteins, which may modulate the ischemic cascade and thus influence the final impact of ischemia.
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Affiliation(s)
- Zuzana Hermanova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine CAS, Prague, Czechia
- Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Lukas Valihrach
- Department of Cellular Neurophysiology, Institute of Experimental Medicine CAS, Prague, Czechia
- Laboratory of Gene Expression, Institute of Biotechnology CAS, Vestec, Czechia
| | - Jan Kriska
- Department of Cellular Neurophysiology, Institute of Experimental Medicine CAS, Prague, Czechia
| | - Mansi Maheta
- Laboratory of Gene Expression, Institute of Biotechnology CAS, Vestec, Czechia
| | - Jana Tureckova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine CAS, Prague, Czechia
| | - Mikael Kubista
- Laboratory of Gene Expression, Institute of Biotechnology CAS, Vestec, Czechia
| | - Miroslava Anderova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine CAS, Prague, Czechia
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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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Lopes DM, Wells JA, Ma D, Wallis L, Park D, Llewellyn SK, Ahmed Z, Lythgoe MF, Harrison IF. Glymphatic inhibition exacerbates tau propagation in an Alzheimer's disease model. Alzheimers Res Ther 2024; 16:71. [PMID: 38576025 PMCID: PMC10996277 DOI: 10.1186/s13195-024-01439-2] [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: 12/18/2023] [Accepted: 03/26/2024] [Indexed: 04/06/2024]
Abstract
BACKGROUND The aggregation and spread of misfolded amyloid structured proteins, such as tau and α-synuclein, are key pathological features associated with neurodegenerative disorders, including Alzheimer's and Parkinson's disease. These proteins possess a prion-like property, enabling their transmission from cell to cell leading to propagation throughout the central and peripheral nervous systems. While the mechanisms underlying their intracellular spread are still being elucidated, targeting the extracellular space has emerged as a potential therapeutic approach. The glymphatic system, a brain-wide pathway responsible for clearing extracellular metabolic waste from the central nervous system, has gained attention as a promising target for removing these toxic proteins. METHODS In this study, we investigated the impact of long-term modulation of glymphatic function on tau aggregation and spread by chronically treating a mouse model of tau propagation with a pharmacological inhibitor of AQP4, TGN-020. Thy1-hTau.P301S mice were intracerebrally inoculated with tau into the hippocampus and overlying cortex, and subsequently treated with TGN-020 (3 doses/week, 50 mg/kg TGN-020, i.p.) for 10-weeks. During this time, animal memory was studied using cognitive behavioural tasks, and structural MR images were acquired of the brain in vivo prior to brain extraction for immunohistochemical characterisation. RESULTS Our findings demonstrate increased tau aggregation in the brain and transhemispheric propagation in the hippocampus following the inhibition of glymphatic clearance. Moreover, disruption of the glymphatic system aggravated recognition memory in tau inoculated mice and exacerbated regional changes in brain volume detected in the model. When initiation of drug treatment was delayed for several weeks post-inoculation, the alterations were attenuated. CONCLUSIONS These results indicate that by modulating AQP4 function and, consequently, glymphatic clearance, it is possible to modify the propagation and pathological impact of tau in the brain, particularly during the initial stages of the disease. These findings highlight the critical role of the glymphatic system in preserving healthy brain homeostasis and offer valuable insights into the therapeutic implications of targeting this system for managing neurodegenerative diseases characterized by protein aggregation and spread.
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Affiliation(s)
- Douglas M Lopes
- Centre for Advanced Biomedical Imaging, Department of Imaging, Division of Medicine, University College London, Paul O'Gorman Building, 72 Huntley Street, London, WC1E 6DD, UK
| | - Jack A Wells
- Centre for Advanced Biomedical Imaging, Department of Imaging, Division of Medicine, University College London, Paul O'Gorman Building, 72 Huntley Street, London, WC1E 6DD, UK
| | - Da Ma
- Department of Internal Medicine, Section of Gerontology and Geriatric Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA
| | - Lauren Wallis
- Centre for Advanced Biomedical Imaging, Department of Imaging, Division of Medicine, University College London, Paul O'Gorman Building, 72 Huntley Street, London, WC1E 6DD, UK
| | - Daniel Park
- Centre for Advanced Biomedical Imaging, Department of Imaging, Division of Medicine, University College London, Paul O'Gorman Building, 72 Huntley Street, London, WC1E 6DD, UK
| | - Sophie K Llewellyn
- Centre for Advanced Biomedical Imaging, Department of Imaging, Division of Medicine, University College London, Paul O'Gorman Building, 72 Huntley Street, London, WC1E 6DD, UK
| | - Zeshan Ahmed
- Neuroscience Next Generation Therapeutics (NGTx), Eli Lilly and Company, Cambridge, MA, USA
| | - Mark F Lythgoe
- Centre for Advanced Biomedical Imaging, Department of Imaging, Division of Medicine, University College London, Paul O'Gorman Building, 72 Huntley Street, London, WC1E 6DD, UK
| | - Ian F Harrison
- Centre for Advanced Biomedical Imaging, Department of Imaging, Division of Medicine, University College London, Paul O'Gorman Building, 72 Huntley Street, London, WC1E 6DD, UK.
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Yuan Y, Peng W, Lei J, Zhao Y, Zhao B, Li Y, Wang J, Qu Q. AQP4 Endocytosis-Lysosome Degradation Mediated by MMP-9/β-DG Involved in Diabetes Cognitive Impairment. Mol Neurobiol 2024:10.1007/s12035-024-04085-9. [PMID: 38512439 DOI: 10.1007/s12035-024-04085-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 02/29/2024] [Indexed: 03/23/2024]
Abstract
Cognitive impairment is considered to be one of the important comorbidities of diabetes, but the underlying mechanisms are widely unknown. Aquaporin-4 (AQP4) is the most abundant water channel in the central nervous system, which plays a neuroprotective role in various neurological diseases by maintaining the function of glymphatic system and synaptic plasticity. However, whether AQP4 is involved in diabetes-related cognitive impairment remains unknown. β-dystroglycan (β-DG), a key molecule for anchoring AQP4 on the plasma membrane of astrocytes and avoiding its targeting to lysosomes for degradation, can be cleaved by matrix metalloproteinase-9 (MMP-9). β-DG deficiency can cause a decline in AQP4 via regulating its endocytosis. However, whether cleavage of β-DG can affect the expression of AQP4 remains unreported. In this study, we observed that diabetes mice displayed cognitive disorder accompanied by reduction of AQP4 in prefrontal cortex. And we found that bafilomycin A1, a widely used lysosome inhibitor, could reverse the downregulation of AQP4 in diabetes, further demonstrating that the reduction of AQP4 in diabetes is a result of more endocytosis-lysosome degradation. In further experiments, we found diabetes caused the excessive activation of MMP-9/β-DG which leaded to the loss of connection between AQP4 and β-DG, further inducing the endocytosis of AQP4. Moreover, inhibition of MMP-9/β-DG restored the endocytosis-lysosome degradation of AQP4 and partially alleviated cognitive dysfunction in diabetes. Our study sheds new light on the role of AQP4 in diabetes-associated cognitive disorder. And we provide a promising therapeutic target to reverse the endocytosis-lysosome degradation of AQP4 in diabetes, such as MMP-9/β-DG.
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Affiliation(s)
- Ye Yuan
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Rd, Xi'an, 710061, China
| | - Wei Peng
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Rd, Xi'an, 710061, China
| | - Jingna Lei
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Rd, Xi'an, 710061, China
| | - Yi Zhao
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Rd, Xi'an, 710061, China
| | - Beiyu Zhao
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Rd, Xi'an, 710061, China
| | - Yan Li
- Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Jin Wang
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Rd, Xi'an, 710061, China.
| | - Qiumin Qu
- Department of Neurology, The First Affiliated Hospital of Xi'an Jiaotong University, 277 West Yanta Rd, Xi'an, 710061, China.
- Center for Brain Science, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China.
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8
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Dong R, Han Y, Lv P, Jiang L, Wang Z, Peng L, Liu S, Ma Z, Xia T, Zhang B, Gu X. Long-term isoflurane anesthesia induces cognitive deficits via AQP4 depolarization mediated blunted glymphatic inflammatory proteins clearance. J Cereb Blood Flow Metab 2024:271678X241237073. [PMID: 38443763 DOI: 10.1177/0271678x241237073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
Perioperative neurocognitive disorders (PND) refer to cognitive deterioration that occurs after surgery or anesthesia. Prolonged isoflurane exposure has potential neurotoxicity and induces PND, but the mechanism is unclear. The glymphatic system clears harmful metabolic waste from the brain. This study sought to unveil the functions of glymphatic system in PND and explore the underlying molecular mechanisms. The PND mice model was established by long term isoflurane anesthesia. The glymphatic function was assessed by multiple in vitro and in vivo methods. An adeno-associated virus was used to overexpress AQP4 and TGN-020 was used to inhibit its function. This research revealed that the glymphatic system was impaired in PND mice and the blunted glymphatic transport was closely associated with the accumulation of inflammatory proteins in the hippocampus. Increasing AQP4 polarization could enhance glymphatic transport and suppresses neuroinflammation, thereby improve cognitive function in the PND model mice. However, a marked impaired glymphatic inflammatory proteins clearance and the more severe cognitive dysfunction were observed when decreasing AQP4 polarization. Therefore, long-term isoflurane anesthesia causes blunted glymphatic system by inducing AQP4 depolarization, enhanced the AQP4 polarization can alleviate the glymphatic system malfunction and reduce the neuroinflammatory response, which may be a potential treatment strategy for PND.
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Affiliation(s)
- Rui Dong
- Department of Anesthesiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Department of Anesthesiology, Qingdao Hospital, University of Health and Rehabilitation Sciences (Qingdao Municipal Hospital), Qingdao, China
| | - Yuqiang Han
- Department of Anesthesiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Pin Lv
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Linhao Jiang
- Department of Anesthesiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Zimo Wang
- Department of Anesthesiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Liangyu Peng
- Department of Anesthesiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Shuai Liu
- Department of Anesthesiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Zhengliang Ma
- Department of Anesthesiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
| | - Tianjiao Xia
- Medical School, Nanjing University, Nanjing, China
- Jiangsu Key Laboratory of Molecular Medicine, Nanjing, China
| | - Bing Zhang
- Department of Radiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
- Medical School, Nanjing University, Nanjing, China
- Institute of Medical Imaging and Artificial Intelligence, Nanjing University, Nanjing, China
- Institute of Brain Science, Nanjing University, Nanjing, China
| | - Xiaoping Gu
- Department of Anesthesiology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, China
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9
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Thormann M, Traube N, Yehia N, Koestler R, Galabova G, MacAulay N, Toft-Bertelsen TL. Toward New AQP4 Inhibitors: ORI-TRN-002. Int J Mol Sci 2024; 25:924. [PMID: 38255997 PMCID: PMC10815436 DOI: 10.3390/ijms25020924] [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: 11/23/2023] [Revised: 01/04/2024] [Accepted: 01/09/2024] [Indexed: 01/24/2024] Open
Abstract
Cerebral edema is a life-threatening condition that can cause permanent brain damage or death if left untreated. Existing therapies aim at mitigating the associated elevated intracranial pressure, yet they primarily alleviate pressure rather than prevent edema formation. Prophylactic anti-edema therapy necessitates novel drugs targeting edema formation. Aquaporin 4 (AQP4), an abundantly expressed water pore in mammalian glia and ependymal cells, has been proposed to be involved in cerebral edema formation. A series of novel compounds have been tested for their potential inhibitory effects on AQP4. However, selectivity, toxicity, functional inhibition, sustained therapeutic concentration, and delivery into the central nervous system are major challenges. Employing extensive density-functional theory (DFT) calculations, we identified a previously unreported thermodynamically stable tautomer of the recently identified AQP4-specific inhibitor TGN-020 (2-(nicotinamide)-1,3,4-thiadiazol). This novel form, featuring a distinct hydrogen-bonding pattern, served as a template for a COSMOsim-3D-based virtual screen of proprietary compounds from Origenis™. The screening identified ORI-TRN-002, an electronic homologue of TGN-020, demonstrating high solubility and low protein binding. Evaluating ORI-TRN-002 on AQP4-expressing Xenopus laevis oocytes using a high-resolution volume recording system revealed an IC50 of 2.9 ± 0.6 µM, establishing it as a novel AQP4 inhibitor. ORI-TRN-002 exhibits superior solubility and overcomes free fraction limitations compared to other reported AQP4 inhibitors, suggesting its potential as a promising anti-edema therapy for treating cerebral edema in the future.
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Affiliation(s)
| | - Nadine Traube
- Origenis GmbH, Am Klopferspitz 19A, 82152 Martinsried, Germany
| | - Nasser Yehia
- Origenis GmbH, Am Klopferspitz 19A, 82152 Martinsried, Germany
| | - Roland Koestler
- Origenis GmbH, Am Klopferspitz 19A, 82152 Martinsried, Germany
| | | | - Nanna MacAulay
- Department of Neuroscience, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark
| | - Trine L. Toft-Bertelsen
- Department of Neuroscience, University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark
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10
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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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11
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He R, Zhang X, Pang C, Lin L, Li S, Jin L, Ding L, Wang W. Inhibition of NADPH oxidase 2 improves cognitive abilities by modulating aquaporin-4 after traumatic brain injury in mice. Heliyon 2023; 9:e22035. [PMID: 38053850 PMCID: PMC10694165 DOI: 10.1016/j.heliyon.2023.e22035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Revised: 09/02/2023] [Accepted: 11/02/2023] [Indexed: 12/07/2023] Open
Abstract
Traumatic brain injury (TBI) is caused by acquired damage that includes cerebral edema after a mechanical injury and may cause cognitive impairment. We explored the role of nicotinamide adenine dinucleotide phosphate oxidase 2 (NADPH oxidase 2; NOX2) and aquaporin-4 (AQP4) in the process of edema and cognitive abilities after TBI in NOX2-/- and AQP4-/- mice by using the Morris water maze test (MWM), step-down test (STD), novel object recognition test (NOR) and western blotting. Knockout of NOX2 in mice decreased the AQP4 and reduce edema in the hippocampus and cortex after TBI in mice. Moreover, inhibiting AQP4 by 2-(nicotinamide)-1,3,4-thiadiazole (TGN-020) or genetic deletion of AQP4 could attenuate neurological deficits without changing reactive oxygen species (ROS) levels after TBI in mice. Taken together, we suspected that inhibiting NOX2 could improve cognitive abilities by modulating ROS levels, then affecting AQP4 levels and brain edema after in TBI mice. Our study demonstrated that NOX2 play a key role in decreasing edema in brain and improving cognitive abilities by modulating AQP4 after TBI.
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Affiliation(s)
- Ruixing He
- Department of Neurosurgery, Huai'an First People's Hospital, Nanjing Medical University, Huai'an, Jiangsu, 223300, China
| | - Xiaotian Zhang
- Department of Neurosurgery, Hongze District People's Hospital of Huai'an City, Huai'an, Jiangsu, 223300, China
| | - Cong Pang
- Department of Neurosurgery, Huai'an First People's Hospital, Nanjing Medical University, Huai'an, Jiangsu, 223300, China
| | - Lihui Lin
- Department of Pharmacy, Zhangzhou Affiliated Hospital of Fujian Medical University, Zhangzhou 363000, China
| | - Shaoxun Li
- Department of Neurosurgery, Huai'an First People's Hospital, Nanjing Medical University, Huai'an, Jiangsu, 223300, China
| | - Luhao Jin
- Department of Neurosurgery, Huai'an First People's Hospital, Nanjing Medical University, Huai'an, Jiangsu, 223300, China
| | - Lianshu Ding
- Department of Neurosurgery, Huai'an First People's Hospital, Nanjing Medical University, Huai'an, Jiangsu, 223300, China
| | - Weijie Wang
- Department of Neurosurgery, Huai'an First People's Hospital, Nanjing Medical University, Huai'an, Jiangsu, 223300, China
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12
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Purnell BS, Alves M, Boison D. Astrocyte-neuron circuits in epilepsy. Neurobiol Dis 2023; 179:106058. [PMID: 36868484 DOI: 10.1016/j.nbd.2023.106058] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 02/20/2023] [Accepted: 02/27/2023] [Indexed: 03/05/2023] Open
Abstract
The epilepsies are a diverse spectrum of disease states characterized by spontaneous seizures and associated comorbidities. Neuron-focused perspectives have yielded an array of widely used anti-seizure medications and are able to explain some, but not all, of the imbalance of excitation and inhibition which manifests itself as spontaneous seizures. Furthermore, the rate of pharmacoresistant epilepsy remains high despite the regular approval of novel anti-seizure medications. Gaining a more complete understanding of the processes that turn a healthy brain into an epileptic brain (epileptogenesis) as well as the processes which generate individual seizures (ictogenesis) may necessitate broadening our focus to other cell types. As will be detailed in this review, astrocytes augment neuronal activity at the level of individual neurons in the form of gliotransmission and the tripartite synapse. Under normal conditions, astrocytes are essential to the maintenance of blood-brain barrier integrity and remediation of inflammation and oxidative stress, but in epilepsy these functions are impaired. Epilepsy results in disruptions in the way astrocytes relate to each other by gap junctions which has important implications for ion and water homeostasis. In their activated state, astrocytes contribute to imbalances in neuronal excitability due to their decreased capacity to take up and metabolize glutamate and an increased capacity to metabolize adenosine. Furthermore, due to their increased adenosine metabolism, activated astrocytes may contribute to DNA hypermethylation and other epigenetic changes that underly epileptogenesis. Lastly, we will explore the potential explanatory power of these changes in astrocyte function in detail in the specific context of the comorbid occurrence of epilepsy and Alzheimer's disease and the disruption in sleep-wake regulation associated with both conditions.
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Affiliation(s)
- Benton S Purnell
- Department of Neurosurgery, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States of America
| | - Mariana Alves
- Department of Neurosurgery, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States of America; Department of Physiology and Medical Physics, Royal College of Surgeons in Ireland, Dublin D02 YN77, Ireland
| | - Detlev Boison
- Department of Neurosurgery, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States of America; Brain Health Institute, Rutgers University, Piscataway, NJ, United States of America.
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13
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Walch E, Fiacco TA. Honey, I shrunk the extracellular space: Measurements and mechanisms of astrocyte swelling. Glia 2022; 70:2013-2031. [PMID: 35635369 PMCID: PMC9474570 DOI: 10.1002/glia.24224] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 05/17/2022] [Accepted: 05/17/2022] [Indexed: 12/16/2022]
Abstract
Astrocyte volume fluctuation is a physiological phenomenon tied closely to the activation of neural circuits. Identification of underlying mechanisms has been challenging due in part to use of a wide range of experimental approaches that vary between research groups. Here, we first review the many methods that have been used to measure astrocyte volume changes directly or indirectly. While the field has recently shifted towards volume analysis using fluorescence microscopy to record cell volume changes directly, established metrics corresponding to extracellular space dynamics have also yielded valuable insights. We then turn to analysis of mechanisms of astrocyte swelling derived from many studies, with a focus on volume changes tied to increases in extracellular potassium concentration ([K+ ]o ). The diverse methods that have been utilized to generate the external [K+ ]o environment highlight multiple scenarios of astrocyte swelling mediated by different mechanisms. Classical potassium buffering theories are tempered by many recent studies that point to different swelling pathways optimized at particular [K+ ]o and that depend on local/transient versus more sustained increases in [K+ ]o .
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Affiliation(s)
- Erin Walch
- Division of Biomedical Sciences, School of MedicineUniversity of California, RiversideRiversideCaliforniaUSA
| | - Todd A. Fiacco
- Department of Molecular, Cell and Systems BiologyUniversity of California, RiversideRiversideCaliforniaUSA
- Center for Glial‐Neuronal InteractionsUniversity of California, RiversideRiversideCaliforniaUSA
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14
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Barbuskaite D, Oernbo EK, Wardman JH, Toft-Bertelsen TL, Conti E, Andreassen SN, Gerkau NJ, Rose CR, MacAulay N. Acetazolamide modulates intracranial pressure directly by its action on the cerebrospinal fluid secretion apparatus. Fluids Barriers CNS 2022; 19:53. [PMID: 35768824 PMCID: PMC9245291 DOI: 10.1186/s12987-022-00348-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 06/01/2022] [Indexed: 01/29/2023] Open
Abstract
Background Elevated intracranial pressure (ICP) is observed in many neurological pathologies, e.g. hydrocephalus and stroke. This condition is routinely relieved with neurosurgical approaches, since effective and targeted pharmacological tools are still lacking. The carbonic anhydrase inhibitor, acetazolamide (AZE), may be employed to treat elevated ICP. However, its effectiveness is questioned, its location of action unresolved, and its tolerability low. Here, we determined the efficacy and mode of action of AZE in the rat . Methods We employed in vivo approaches including ICP and cerebrospinal fluid secretion measurements in anaesthetized rats and telemetric monitoring of ICP and blood pressure in awake rats in combination with ex vivo choroidal radioisotope flux assays and transcriptomic analysis. Results AZE effectively reduced the ICP, irrespective of the mode of drug administration and level of anaesthesia. The effect appeared to occur via a direct action on the choroid plexus and an associated decrease in cerebrospinal fluid secretion, and not indirectly via the systemic action of AZE on renal and vascular processes. Upon a single administration, the reduced ICP endured for approximately 10 h post-AZE delivery with no long-term changes of brain water content or choroidal transporter expression. However, a persistent reduction of ICP was secured with repeated AZE administrations throughout the day. Conclusions AZE lowers ICP directly via its ability to reduce the choroid plexus CSF secretion, irrespective of mode of drug administration. Supplementary Information The online version contains supplementary material available at 10.1186/s12987-022-00348-6.
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Affiliation(s)
- Dagne Barbuskaite
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Eva K Oernbo
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Jonathan H Wardman
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Trine L Toft-Bertelsen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Eller Conti
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Søren N Andreassen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Niklas J Gerkau
- Institute of Neurobiology, Heinrich Heine University, Universitätsstrasse 1, 40225, Düsseldorf, Germany
| | - Christine R Rose
- Institute of Neurobiology, Heinrich Heine University, Universitätsstrasse 1, 40225, Düsseldorf, Germany
| | - Nanna MacAulay
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark.
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15
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Chiang PP, Kuo SP, Newman EA. Cellular mechanisms mediating activity-dependent extracellular space shrinkage in the retina. Glia 2022; 70:1927-1937. [PMID: 35678626 PMCID: PMC9378592 DOI: 10.1002/glia.24228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 05/25/2022] [Accepted: 05/26/2022] [Indexed: 11/30/2022]
Abstract
Volume transmission plays an essential role in CNS function, with neurotransmitters released from synapses diffusing through the extracellular space (ECS) to distant sites. Changes in the ECS volume fraction (α) will influence the diffusion and the concentration of transmitters within the ECS. We have recently shown that neuronal activity evoked by physiological photic stimuli results in rapid decreases in ECS α as large as 10% in the retina. We now characterize the cellular mechanisms responsible for this ECS shrinkage. We find that block of inwardly rectifying K+ channels with Ba2+, inhibition of the Na+/K+/2Cl− cotransporter with bumetanide, or block of AQP4 water channels with TGN‐020 do not diminish the light‐evoked ECS decrease. Inhibition of the Na+/HCO3− cotransporter by removing HCO3− from the superfusate, in contrast, reduces the light‐evoked ECS decrease by 95.6%. Inhibition of the monocarboxylate transporter with alpha‐cyano‐4‐hydroxycinnamate (4‐CIN) also reduces the ECS shrinkage, but only by 32.5%. We tested whether the swelling of Müller cells, the principal glial cells of the retina, is responsible for the light‐evoked ECS shrinkage. Light stimulation evoked a 6.3% increase in the volume of the fine processes of Müller cells. This volume increase was reduced by 97.1% when HCO3− was removed from the superfusate. We conclude that a large fraction of the activity‐dependent decrease in ECS α is generated by the activation of the Na+/HCO3− cotransporter in Müller cells. The monocarboxylate transporter may also contribute to the response.
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Affiliation(s)
- Pei-Pei Chiang
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Sidney P Kuo
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
| | - Eric A Newman
- Department of Neuroscience, University of Minnesota, Minneapolis, Minnesota, USA
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16
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Simon M, Wang MX, Ismail O, Braun M, Schindler AG, Reemmer J, Wang Z, Haveliwala MA, O’Boyle RP, Han WY, Roese N, Grafe M, Woltjer R, Boison D, Iliff JJ. Loss of perivascular aquaporin-4 localization impairs glymphatic exchange and promotes amyloid β plaque formation in mice. Alzheimers Res Ther 2022; 14:59. [PMID: 35473943 PMCID: PMC9040291 DOI: 10.1186/s13195-022-00999-5] [Citation(s) in RCA: 59] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Accepted: 04/04/2022] [Indexed: 02/02/2023]
Abstract
BACKGROUND Slowed clearance of amyloid β (Aβ) is believed to underlie the development of Aβ plaques that characterize Alzheimer's disease (AD). Aβ is cleared in part by the glymphatic system, a brain-wide network of perivascular pathways that supports the exchange of cerebrospinal and brain interstitial fluid. Glymphatic clearance, or perivascular CSF-interstitial fluid exchange, is dependent on the astroglial water channel aquaporin-4 (AQP4) as deletion of Aqp4 in mice slows perivascular exchange, impairs Aβ clearance, and promotes Aβ plaque formation. METHODS To define the role of AQP4 in human AD, we evaluated AQP4 expression and localization in a human post mortem case series. We then used the α-syntrophin (Snta1) knockout mouse model which lacks perivascular AQP4 localization to evaluate the effect that loss of perivascular AQP4 localization has on glymphatic CSF tracer distribution. Lastly, we crossed this line into a mouse model of amyloidosis (Tg2576 mice) to evaluate the effect of AQP4 localization on amyloid β levels. RESULTS In the post mortem case series, we observed that the perivascular localization of AQP4 is reduced in frontal cortical gray matter of subjects with AD compared to cognitively intact subjects. This decline in perivascular AQP4 localization was associated with increasing Aβ and neurofibrillary pathological burden, and with cognitive decline prior to dementia onset. In rodent studies, Snta1 gene deletion slowed CSF tracer influx and interstitial tracer efflux from the mouse brain and increased amyloid β levels. CONCLUSIONS These findings suggest that the loss of perivascular AQP4 localization may contribute to the development of AD pathology in human populations.
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Affiliation(s)
- Matthew Simon
- Neuroscience Graduate Program, Oregon Health & Science University, Portland, OR USA
- Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR USA
| | - Marie Xun Wang
- Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR USA
- Department of Psychiatry and Behavioral Sciences, University of Washington School of Medicine, Seattle, WA USA
| | - Ozama Ismail
- Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR USA
- Center for Advanced Biomedical Imaging, University College London, London, UK
| | - Molly Braun
- Department of Psychiatry and Behavioral Sciences, University of Washington School of Medicine, Seattle, WA USA
- VISN 20 Mental Illness Research, Education and Clinical Center (MIRECC), VA Puget Sound Health Care System, 1660 S Columbian Wy., Seattle, WA 98108 USA
| | - Abigail G. Schindler
- Department of Psychiatry and Behavioral Sciences, University of Washington School of Medicine, Seattle, WA USA
- VISN 20 Geriatric Research, Education and Clinical Center (GRECC), VA Puget Sound Health Care System, Seattle, WA USA
| | - Jesica Reemmer
- Robert Stone Dow Neurobiology Laboratories, Legacy Research Institute, Portland, OR USA
| | - Zhongya Wang
- Robert Stone Dow Neurobiology Laboratories, Legacy Research Institute, Portland, OR USA
| | - Mariya A. Haveliwala
- VISN 20 Mental Illness Research, Education and Clinical Center (MIRECC), VA Puget Sound Health Care System, 1660 S Columbian Wy., Seattle, WA 98108 USA
| | - Ryan P. O’Boyle
- VISN 20 Mental Illness Research, Education and Clinical Center (MIRECC), VA Puget Sound Health Care System, 1660 S Columbian Wy., Seattle, WA 98108 USA
| | - Warren Y. Han
- VISN 20 Mental Illness Research, Education and Clinical Center (MIRECC), VA Puget Sound Health Care System, 1660 S Columbian Wy., Seattle, WA 98108 USA
| | - Natalie Roese
- Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR USA
| | - Marjorie Grafe
- Department of Pathology, Oregon Health & Science University, Portland, OR USA
| | - Randall Woltjer
- Department of Pathology, Oregon Health & Science University, Portland, OR USA
| | - Detlev Boison
- Department of Neurosurgery, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ USA
| | - Jeffrey J. Iliff
- Department of Anesthesiology and Perioperative Medicine, Oregon Health & Science University, Portland, OR USA
- Department of Psychiatry and Behavioral Sciences, University of Washington School of Medicine, Seattle, WA USA
- VISN 20 Mental Illness Research, Education and Clinical Center (MIRECC), VA Puget Sound Health Care System, 1660 S Columbian Wy., Seattle, WA 98108 USA
- Knight Cardiovascular Institute, Oregon Health & Science University, Portland, OR USA
- Department of Neurology, University of Washington School of Medicine, Seattle, WA USA
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17
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Tureckova J, Kamenicka M, Kolenicova D, Filipi T, Hermanova Z, Kriska J, Meszarosova L, Pukajova B, Valihrach L, Androvic P, Zucha D, Chmelova M, Vargova L, Anderova M. Compromised Astrocyte Swelling/Volume Regulation in the Hippocampus of the Triple Transgenic Mouse Model of Alzheimer’s Disease. Front Aging Neurosci 2022; 13:783120. [PMID: 35153718 PMCID: PMC8829436 DOI: 10.3389/fnagi.2021.783120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2021] [Accepted: 12/27/2021] [Indexed: 11/13/2022] Open
Abstract
In this study, we aimed to disclose the impact of amyloid-β toxicity and tau pathology on astrocyte swelling, their volume recovery and extracellular space (ECS) diffusion parameters, namely volume fraction (α) and tortuosity (λ), in a triple transgenic mouse model of Alzheimer’s disease (3xTg-AD). Astrocyte volume changes, which reflect astrocyte ability to take up ions/neurotransmitters, were quantified during and after exposure to hypo-osmotic stress, or hyperkalemia in acute hippocampal slices, and were correlated with alterations in ECS diffusion parameters. Astrocyte volume and ECS diffusion parameters were monitored during physiological aging (controls) and during AD progression in 3-, 9-, 12- and 18-month-old mice. In the hippocampus of controls α gradually declined with age, while it remained unaffected in 3xTg-AD mice during the entire time course. Moreover, age-related increases in λ occurred much earlier in 3xTg-AD animals than in controls. In 3xTg-AD mice changes in α induced by hypo-osmotic stress or hyperkalemia were comparable to those observed in controls, however, AD progression affected α recovery following exposure to both. Compared to controls, a smaller astrocyte swelling was detected in 3xTg-AD mice only during hyperkalemia. Since we observed a large variance in astrocyte swelling/volume regulation, we divided them into high- (HRA) and low-responding astrocytes (LRA). In response to hyperkalemia, the incidence of LRA was higher in 3xTg-AD mice than in controls, which may also reflect compromised K+ and neurotransmitter uptake. Furthermore, we performed single-cell RT-qPCR to identify possible age-related alterations in astrocytic gene expression profiles. Already in 3-month-old 3xTg-AD mice, we detected a downregulation of genes affecting the ion/neurotransmitter uptake and cell volume regulation, namely genes of glutamate transporters, α2β2 subunit of Na+/K+-ATPase, connexin 30 or Kir4.1 channel. In conclusion, the aged hippocampus of 3xTg-AD mice displays an enlarged ECS volume fraction and an increased number of obstacles, which emerge earlier than in physiological aging. Both these changes may strongly affect intercellular communication and influence astrocyte ionic/neurotransmitter uptake, which becomes impaired during aging and this phenomenon is manifested earlier in 3xTg-AD mice. The increased incidence of astrocytes with limited ability to take up ions/neurotransmitters may further add to a cytotoxic environment.
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Affiliation(s)
- Jana Tureckova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czechia
- *Correspondence: Jana Tureckova,
| | - Monika Kamenicka
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czechia
- Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Denisa Kolenicova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czechia
- Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Tereza Filipi
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czechia
- Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Zuzana Hermanova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czechia
- Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Jan Kriska
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czechia
| | - Lenka Meszarosova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czechia
| | - Barbora Pukajova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czechia
| | - Lukas Valihrach
- Laboratory of Gene Expression, Institute of Biotechnology, Czech Academy of Sciences, Vestec, Czechia
| | - Peter Androvic
- Laboratory of Gene Expression, Institute of Biotechnology, Czech Academy of Sciences, Vestec, Czechia
| | - Daniel Zucha
- Laboratory of Gene Expression, Institute of Biotechnology, Czech Academy of Sciences, Vestec, Czechia
- Faculty of Chemical Technology, University of Chemistry and Technology, Prague, Czechia
| | - Martina Chmelova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czechia
- Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Lydia Vargova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czechia
- Second Faculty of Medicine, Charles University, Prague, Czechia
| | - Miroslava Anderova
- Department of Cellular Neurophysiology, Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czechia
- Second Faculty of Medicine, Charles University, Prague, Czechia
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18
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Salman MM, Kitchen P, Yool AJ, Bill RM. Recent breakthroughs and future directions in drugging aquaporins. Trends Pharmacol Sci 2022; 43:30-42. [PMID: 34863533 DOI: 10.1016/j.tips.2021.10.009] [Citation(s) in RCA: 57] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 09/09/2021] [Accepted: 10/18/2021] [Indexed: 02/06/2023]
Abstract
Aquaporins facilitate the passive transport of water, solutes, or ions across biological membranes. They are implicated in diverse pathologies including brain edema following stroke or trauma, epilepsy, cancer cell migration and tumor angiogenesis, metabolic disorders, and inflammation. Despite this, there is no aquaporin-targeted drug in the clinic and aquaporins have been perceived to be intrinsically non-druggable targets. Here we challenge this idea, as viable routes to inhibition of aquaporin function have recently been identified, including targeting their regulation or their roles as channels for unexpected substrates. Identifying new drug development frameworks for conditions associated with disrupted water and solute homeostasis will meet the urgent, unmet clinical need of millions of patients for whom no pharmacological interventions are available.
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Affiliation(s)
- Mootaz M Salman
- Department of Physiology, Anatomy and Genetics, Kavli Institute for NanoScience Discovery, University of Oxford, Oxford OX1 3PT, UK; Oxford Parkinson's Disease Centre, University of Oxford, Oxford, UK.
| | - Philip Kitchen
- School of Biosciences, College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK.
| | - Andrea J Yool
- University of Adelaide, School of Biomedicine, Adelaide, South Australia 5005, Australia.
| | - Roslyn M Bill
- School of Biosciences, College of Health and Life Sciences, Aston University, Birmingham B4 7ET, UK.
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19
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Szczygielski J, Kopańska M, Wysocka A, Oertel J. Cerebral Microcirculation, Perivascular Unit, and Glymphatic System: Role of Aquaporin-4 as the Gatekeeper for Water Homeostasis. Front Neurol 2021; 12:767470. [PMID: 34966347 PMCID: PMC8710539 DOI: 10.3389/fneur.2021.767470] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 11/12/2021] [Indexed: 12/13/2022] Open
Abstract
In the past, water homeostasis of the brain was understood as a certain quantitative equilibrium of water content between intravascular, interstitial, and intracellular spaces governed mostly by hydrostatic effects i.e., strictly by physical laws. The recent achievements in molecular bioscience have led to substantial changes in this regard. Some new concepts elaborate the idea that all compartments involved in cerebral fluid homeostasis create a functional continuum with an active and precise regulation of fluid exchange between them rather than only serving as separate fluid receptacles with mere passive diffusion mechanisms, based on hydrostatic pressure. According to these concepts, aquaporin-4 (AQP4) plays the central role in cerebral fluid homeostasis, acting as a water channel protein. The AQP4 not only enables water permeability through the blood-brain barrier but also regulates water exchange between perivascular spaces and the rest of the glymphatic system, described as pan-cerebral fluid pathway interlacing macroscopic cerebrospinal fluid (CSF) spaces with the interstitial fluid of brain tissue. With regards to this, AQP4 makes water shift strongly dependent on active processes including changes in cerebral microcirculation and autoregulation of brain vessels capacity. In this paper, the role of the AQP4 as the gatekeeper, regulating the water exchange between intracellular space, glymphatic system (including the so-called neurovascular units), and intravascular compartment is reviewed. In addition, the new concepts of brain edema as a misbalance in water homeostasis are critically appraised based on the newly described role of AQP4 for fluid permeation. Finally, the relevance of these hypotheses for clinical conditions (including brain trauma and stroke) and for both new and old therapy concepts are analyzed.
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Affiliation(s)
- Jacek Szczygielski
- Department of Neurosurgery, Institute of Medical Sciences, University of Rzeszów, Rzeszów, Poland.,Department of Neurosurgery, Faculty of Medicine and Saarland University Medical Center, Saarland University, Homburg, Germany
| | - Marta Kopańska
- Department of Pathophysiology, Institute of Medical Sciences, University of Rzeszów, Rzeszów, Poland
| | - Anna Wysocka
- Chair of Internal Medicine and Department of Internal Medicine in Nursing, Faculty of Health Sciences, Medical University of Lublin, Lublin, Poland
| | - Joachim Oertel
- Department of Neurosurgery, Faculty of Medicine and Saarland University Medical Center, Saarland University, Homburg, Germany
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20
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Engels M, Kalia M, Rahmati S, Petersilie L, Kovermann P, van Putten MJAM, Rose CR, Meijer HGE, Gensch T, Fahlke C. Glial Chloride Homeostasis Under Transient Ischemic Stress. Front Cell Neurosci 2021; 15:735300. [PMID: 34602981 PMCID: PMC8481871 DOI: 10.3389/fncel.2021.735300] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 08/23/2021] [Indexed: 12/17/2022] Open
Abstract
High water permeabilities permit rapid adjustments of glial volume upon changes in external and internal osmolarity, and pathologically altered intracellular chloride concentrations ([Cl–]int) and glial cell swelling are often assumed to represent early events in ischemia, infections, or traumatic brain injury. Experimental data for glial [Cl–]int are lacking for most brain regions, under normal as well as under pathological conditions. We measured [Cl–]int in hippocampal and neocortical astrocytes and in hippocampal radial glia-like (RGL) cells in acute murine brain slices using fluorescence lifetime imaging microscopy with the chloride-sensitive dye MQAE at room temperature. We observed substantial heterogeneity in baseline [Cl–]int, ranging from 14.0 ± 2.0 mM in neocortical astrocytes to 28.4 ± 3.0 mM in dentate gyrus astrocytes. Chloride accumulation by the Na+-K+-2Cl– cotransporter (NKCC1) and chloride outward transport (efflux) through K+-Cl– cotransporters (KCC1 and KCC3) or excitatory amino acid transporter (EAAT) anion channels control [Cl–]int to variable extent in distinct brain regions. In hippocampal astrocytes, blocking NKCC1 decreased [Cl–]int, whereas KCC or EAAT anion channel inhibition had little effect. In contrast, neocortical astrocytic or RGL [Cl–]int was very sensitive to block of chloride outward transport, but not to NKCC1 inhibition. Mathematical modeling demonstrated that higher numbers of NKCC1 and KCC transporters can account for lower [Cl–]int in neocortical than in hippocampal astrocytes. Energy depletion mimicking ischemia for up to 10 min did not result in pronounced changes in [Cl–]int in any of the tested glial cell types. However, [Cl–]int changes occurred under ischemic conditions after blocking selected anion transporters. We conclude that stimulated chloride accumulation and chloride efflux compensate for each other and prevent glial swelling under transient energy deprivation.
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Affiliation(s)
- Miriam Engels
- Institute of Biological Information Processing, Molekular-und Zellphysiologie (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Manu Kalia
- Applied Analysis, Department of Applied Mathematics, University of Twente, Enschede, Netherlands.,Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Sarah Rahmati
- Institute of Biological Information Processing, Molekular-und Zellphysiologie (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Laura Petersilie
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Peter Kovermann
- Institute of Biological Information Processing, Molekular-und Zellphysiologie (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | | | - Christine R Rose
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Hil G E Meijer
- Applied Analysis, Department of Applied Mathematics, University of Twente, Enschede, Netherlands
| | - Thomas Gensch
- Institute of Biological Information Processing, Molekular-und Zellphysiologie (IBI-1), Forschungszentrum Jülich, Jülich, Germany
| | - Christoph Fahlke
- Institute of Biological Information Processing, Molekular-und Zellphysiologie (IBI-1), Forschungszentrum Jülich, Jülich, Germany
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21
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Hellas JA, Andrew RD. Neuronal Swelling: A Non-osmotic Consequence of Spreading Depolarization. Neurocrit Care 2021; 35:112-134. [PMID: 34498208 PMCID: PMC8536653 DOI: 10.1007/s12028-021-01326-w] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 08/04/2021] [Indexed: 01/22/2023]
Abstract
An acute reduction in plasma osmolality causes rapid uptake of water by astrocytes but not by neurons, whereas both cell types swell as a consequence of lost blood flow (ischemia). Either hypoosmolality or ischemia can displace the brain downwards, potentially causing death. However, these disorders are fundamentally different at the cellular level. Astrocytes osmotically swell or shrink because they express functional water channels (aquaporins), whereas neurons lack functional aquaporins and thus maintain their volume. Yet both neurons and astrocytes immediately swell when blood flow to the brain is compromised (cytotoxic edema) as following stroke onset, sudden cardiac arrest, or traumatic brain injury. In each situation, neuronal swelling is the direct result of spreading depolarization (SD) generated when the ATP-dependent sodium/potassium ATPase (the Na+/K+ pump) is compromised. The simple, and incorrect, textbook explanation for neuronal swelling is that increased Na+ influx passively draws Cl- into the cell, with water following by osmosis via some unknown conduit. We first review the strong evidence that mammalian neurons resist volume change during acute osmotic stress. We then contrast this with their dramatic swelling during ischemia. Counter-intuitively, recent research argues that ischemic swelling of neurons is non-osmotic, involving ion/water cotransporters as well as at least one known amino acid water pump. While incompletely understood, these mechanisms argue against the dogma that neuronal swelling involves water uptake driven by an osmotic gradient with aquaporins as the conduit. Promoting clinical recovery from neuronal cytotoxic edema evoked by spreading depolarizations requires a far better understanding of molecular water pumps and ion/water cotransporters that act to rebalance water shifts during brain ischemia.
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Affiliation(s)
- Julia A Hellas
- Center for Neuroscience Studies, Queen's University, Kingston, ON, K7L 3N6, Canada.
| | - R David Andrew
- Center for Neuroscience Studies, Queen's University, Kingston, ON, K7L 3N6, Canada
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22
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Molecular Mechanisms of Neuroimmune Crosstalk in the Pathogenesis of Stroke. Int J Mol Sci 2021; 22:ijms22179486. [PMID: 34502395 PMCID: PMC8431165 DOI: 10.3390/ijms22179486] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 08/26/2021] [Accepted: 08/28/2021] [Indexed: 12/21/2022] Open
Abstract
Stroke disrupts the homeostatic balance within the brain and is associated with a significant accumulation of necrotic cellular debris, fluid, and peripheral immune cells in the central nervous system (CNS). Additionally, cells, antigens, and other factors exit the brain into the periphery via damaged blood–brain barrier cells, glymphatic transport mechanisms, and lymphatic vessels, which dramatically influence the systemic immune response and lead to complex neuroimmune communication. As a result, the immunological response after stroke is a highly dynamic event that involves communication between multiple organ systems and cell types, with significant consequences on not only the initial stroke tissue injury but long-term recovery in the CNS. In this review, we discuss the complex immunological and physiological interactions that occur after stroke with a focus on how the peripheral immune system and CNS communicate to regulate post-stroke brain homeostasis. First, we discuss the post-stroke immune cascade across different contexts as well as homeostatic regulation within the brain. Then, we focus on the lymphatic vessels surrounding the brain and their ability to coordinate both immune response and fluid homeostasis within the brain after stroke. Finally, we discuss how therapeutic manipulation of peripheral systems may provide new mechanisms to treat stroke injury.
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23
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MacAulay N. Reply to 'Aquaporin 4 and glymphatic flow have central roles in brain fluid homeostasis'. Nat Rev Neurosci 2021; 22:651-652. [PMID: 34408335 DOI: 10.1038/s41583-021-00515-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Nanna MacAulay
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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24
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Netti V, Fernández J, Melamud L, Garcia-Miranda P, Di Giusto G, Ford P, Echevarría M, Capurro C. Aquaporin-4 Removal from the Plasma Membrane of Human Müller Cells by AQP4-IgG from Patients with Neuromyelitis Optica Induces Changes in Cell Volume Homeostasis: the First Step of Retinal Injury? Mol Neurobiol 2021; 58:5178-5193. [PMID: 34263427 DOI: 10.1007/s12035-021-02491-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2021] [Accepted: 07/11/2021] [Indexed: 11/27/2022]
Abstract
Aquaporin-4 (AQP4) is the target of the specific immunoglobulin G autoantibody (AQP4-IgG) produced in patients with neuromyelitis optica spectrum disorders (NMOSD). Previous studies demonstrated that AQP4-IgG binding to astrocytic AQP4 leads to cell-destructive lesions. However, the early physiopathological events in Müller cells in the retina are poorly understood. Here, we investigated the consequences of AQP4-IgG binding to AQP4 of Müller cells, previous to the inflammatory response, on two of AQP4's key functions, cell volume regulation response (RVD) and cell proliferation, a process closely associated with changes in cell volume. Experiments were performed in a human retinal Müller cell line (MIO-M1) exposed to complement-inactivated sera from healthy volunteers or AQP4-IgG positive NMOSD patients. We evaluated AQP4 expression (immunofluorescence and western blot), water permeability coefficient, RVD, intracellular calcium levels and membrane potential changes during hypotonic shock (fluorescence videomicroscopy) and cell proliferation (cell count and BrdU incorporation). Our results showed that AQP4-IgG binding to AQP4 induces its partial internalization, leading to the decrease of the plasma membrane water permeability, a reduction of swelling-induced increase of intracellular calcium levels and the impairment of RVD in Müller cells. The loss of AQP4 from the plasma membrane induced by AQP4-IgG positive sera delayed Müller cells' proliferation rate. We propose that Müller cell dysfunction after AQP4 removal from the plasma membrane by AQP4-IgG binding could be a non-inflammatory mechanism of retinal injury in vivo, altering cell volume homeostasis and cell proliferation and consequently, contributing to the physiopathology of NMOSD.
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Affiliation(s)
- Vanina Netti
- Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas, Facultad de Medicina, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-HOUSSAY), Consejo Nacional de Investigaciones Científicas Y Técnicas (CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Juan Fernández
- Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas, Facultad de Medicina, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-HOUSSAY), Consejo Nacional de Investigaciones Científicas Y Técnicas (CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Luciana Melamud
- Servicio de Neurología, Centro Universitario de Neurología Dr. J.M. Ramos Mejía, Facultad de Medicina, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Pablo Garcia-Miranda
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC, Universidad de Sevilla, Seville, Spain
| | - Gisela Di Giusto
- Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas, Facultad de Medicina, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-HOUSSAY), Consejo Nacional de Investigaciones Científicas Y Técnicas (CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Paula Ford
- Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas, Facultad de Medicina, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-HOUSSAY), Consejo Nacional de Investigaciones Científicas Y Técnicas (CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Miriam Echevarría
- Instituto de Biomedicina de Sevilla (IBiS), Hospital Universitario Virgen del Rocío/CSIC, Universidad de Sevilla, Seville, Spain
| | - Claudia Capurro
- Departamento de Ciencias Fisiológicas, Laboratorio de Biomembranas, Facultad de Medicina, Instituto de Fisiología y Biofísica "Bernardo Houssay" (IFIBIO-HOUSSAY), Consejo Nacional de Investigaciones Científicas Y Técnicas (CONICET), Universidad de Buenos Aires, Buenos Aires, Argentina.
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25
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Abstract
Our brains consist of 80% water, which is continuously shifted between different compartments and cell types during physiological and pathophysiological processes. Disturbances in brain water homeostasis occur with pathologies such as brain oedema and hydrocephalus, in which fluid accumulation leads to elevated intracranial pressure. Targeted pharmacological treatments do not exist for these conditions owing to our incomplete understanding of the molecular mechanisms governing brain water transport. Historically, the transmembrane movement of brain water was assumed to occur as passive movement of water along the osmotic gradient, greatly accelerated by water channels termed aquaporins. Although aquaporins govern the majority of fluid handling in the kidney, they do not suffice to explain the overall brain water movement: either they are not present in the membranes across which water flows or they appear not to be required for the observed flow of water. Notably, brain fluid can be secreted against an osmotic gradient, suggesting that conventional osmotic water flow may not describe all transmembrane fluid transport in the brain. The cotransport of water is an unconventional molecular mechanism that is introduced in this Review as a missing link to bridge the gap in our understanding of cellular and barrier brain water transport.
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Affiliation(s)
- Nanna MacAulay
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
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26
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Colbourn R, Hrabe J, Nicholson C, Perkins M, Goodman JH, Hrabetova S. Rapid volume pulsation of the extracellular space coincides with epileptiform activity in mice and depends on the NBCe1 transporter. J Physiol 2021; 599:3195-3220. [PMID: 33942325 DOI: 10.1113/jp281544] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 04/19/2021] [Indexed: 01/06/2023] Open
Abstract
KEY POINTS Extracellular space (ECS) rapid volume pulsation (RVP) accompanying epileptiform activity is described for the first time. Such RVP occurs robustly in several in vitro and in vivo mouse models of epileptiform activity. In the in vitro 4-aminopyridine model of epileptiform activity, RVP depends on the activity of the electrogenic Na+ /HCO3 - cotransporter (NBCe1). NBCe1 pharmacological inhibition suppresses RVP and epileptiform activity. Inhibition of changes in ECS volume may be a useful target in epilepsy patients who are resistant to current treatments. ABSTRACT: The extracellular space (ECS) of the brain shrinks persistently by approximately 35% during epileptic seizures. Here we report the discovery of rapid volume pulsation (RVP), further transient drops in ECS volume which accompany events of epileptiform activity. These transient ECS contractions were observed in multiple mouse models of epileptiform activity both in vivo (bicuculline methiodide model) and in vitro (hyaluronan synthase 3 knock-out, picrotoxin, bicuculline and 4-aminopyridine models). By using the probe transients quantification (PTQ) method we show that individual pulses of RVP shrank the ECS by almost 15% in vivo. In the 4-aminopyridine in vitro model, the individual pulses of RVP shrank the ECS by more than 4%, and these transient changes were superimposed on a persistent ECS shrinkage of 36% measured with the real-time iontophoretic method. In this in vitro model, we investigated several channels and transporters that may be required for the generation of RVP and epileptiform activity. Pharmacological blockages of Na+ /K+ /2Cl- cotransporter type 1 (NKCC1), K+ /Cl- cotransporter (KCC2), the water channel aquaporin-4 (AQP4) and inwardly rectifying potassium channel 4.1 (Kir4.1) were ineffective in halting the RVP and the epileptiform activity. In contrast, pharmacological blockade of the electrogenic Na+ /HCO3 - cotransporter (NBCe1) by 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS) eliminated both the RVP and the persistent ECS shrinkage. Importantly, this blocker also stopped the epileptiform activity. These results demonstrate that RVP is closely associated with epileptiform activity across several models of epileptiform activity and therefore the underlying mechanism could potentially represent a novel target for epilepsy management and treatment.
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Affiliation(s)
- Robert Colbourn
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York, USA.,Neural and Behavioral Science Graduate Program, SUNY Downstate Health Sciences University, Brooklyn, New York, USA
| | - Jan Hrabe
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York, USA.,Medical Physics Laboratory, Center for Biomedical Imaging and Neuromodulation, Nathan S. Kline Institute, Orangeburg, New York, USA
| | - Charles Nicholson
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York, USA.,Department of Neuroscience and Physiology, NYU Grossman School of Medicine, New York, New York, USA
| | - Matthew Perkins
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York, USA
| | - Jeffrey H Goodman
- Department of Developmental Neurobiology, The New York State Institute for Basic Research in Developmental Disabilities, Staten Island, New York, USA.,Department of Physiology and Pharmacology, SUNY Downstate Health Sciences University, Brooklyn, New York, USA.,Department of Neurology, SUNY Downstate Health Sciences University, Brooklyn, New York, USA.,The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Health Sciences University, Brooklyn, New York, USA
| | - Sabina Hrabetova
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, New York, USA.,The Robert F. Furchgott Center for Neural and Behavioral Science, SUNY Downstate Health Sciences University, Brooklyn, New York, USA
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27
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van Putten MJ, Fahlke C, Kafitz KW, Hofmeijer J, Rose CR. Dysregulation of Astrocyte Ion Homeostasis and Its Relevance for Stroke-Induced Brain Damage. Int J Mol Sci 2021; 22:5679. [PMID: 34073593 PMCID: PMC8198632 DOI: 10.3390/ijms22115679] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Revised: 05/21/2021] [Accepted: 05/22/2021] [Indexed: 12/14/2022] Open
Abstract
Ischemic stroke is a leading cause of mortality and chronic disability. Either recovery or progression towards irreversible failure of neurons and astrocytes occurs within minutes to days, depending on remaining perfusion levels. Initial damage arises from energy depletion resulting in a failure to maintain homeostasis and ion gradients between extra- and intracellular spaces. Astrocytes play a key role in these processes and are thus central players in the dynamics towards recovery or progression of stroke-induced brain damage. Here, we present a synopsis of the pivotal functions of astrocytes at the tripartite synapse, which form the basis of physiological brain functioning. We summarize the evidence of astrocytic failure and its consequences under ischemic conditions. Special emphasis is put on the homeostasis and stroke-induced dysregulation of the major monovalent ions, namely Na+, K+, H+, and Cl-, and their involvement in maintenance of cellular volume and generation of cerebral edema.
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Affiliation(s)
- Michel J.A.M. van Putten
- Department of Clinical Neurophysiology, University of Twente, 7522 NB Enschede, The Netherlands; (M.J.A.M.v.P.); (J.H.)
| | - Christoph Fahlke
- Institut für Biologische Informationsprozesse, Molekular-und Zellphysiologie (IBI-1), Forschungszentrum Jülich, 52425 Jülich, Germany;
| | - Karl W. Kafitz
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany;
| | - Jeannette Hofmeijer
- Department of Clinical Neurophysiology, University of Twente, 7522 NB Enschede, The Netherlands; (M.J.A.M.v.P.); (J.H.)
| | - Christine R. Rose
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, 40225 Düsseldorf, Germany;
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28
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Walch E, Murphy TR, Cuvelier N, Aldoghmi M, Morozova C, Donohue J, Young G, Samant A, Garcia S, Alvarez C, Bilas A, Davila D, Binder DK, Fiacco TA. Astrocyte-Selective Volume Increase in Elevated Extracellular Potassium Conditions Is Mediated by the Na +/K + ATPase and Occurs Independently of Aquaporin 4. ASN Neuro 2020; 12:1759091420967152. [PMID: 33092407 PMCID: PMC7586494 DOI: 10.1177/1759091420967152] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 09/23/2020] [Indexed: 12/26/2022] Open
Abstract
Astrocytes and neurons have been shown to swell across a variety of different conditions, including increases in extracellular potassium concentration (^[K+]o). The mechanisms involved in the coupling of K+ influx to water movement into cells leading to cell swelling are not well understood and remain controversial. Here, we set out to determine the effects of ^[K+]o on rapid volume responses of hippocampal CA1 pyramidal neurons and stratum radiatum astrocytes using real-time confocal volume imaging. First, we found that elevating [K+]o within a physiological range (to 6.5 mM and 10.5 mM from a baseline of 2.5 mM), and even up to pathological levels (26 mM), produced dose-dependent increases in astrocyte volume, with absolutely no effect on neuronal volume. In the absence of compensating for addition of KCl by removal of an equal amount of NaCl, neurons actually shrank in ^[K+]o, while astrocytes continued to exhibit rapid volume increases. Astrocyte swelling in ^[K+]o was not dependent on neuronal firing, aquaporin 4, the inwardly rectifying potassium channel Kir 4.1, the sodium bicarbonate cotransporter NBCe1, , or the electroneutral cotransporter, sodium-potassium-chloride cotransporter type 1 (NKCC1), but was significantly attenuated in 1 mM barium chloride (BaCl2) and by the Na+/K+ ATPase inhibitor ouabain. Effects of 1 mM BaCl2 and ouabain applied together were not additive and, together with reports that BaCl2 can inhibit the NKA at high concentrations, suggests a prominent role for the astrocyte NKA in rapid astrocyte volume increases occurring in ^[K+]o. These findings carry important implications for understanding mechanisms of cellular edema, regulation of the brain extracellular space, and brain tissue excitability.
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Affiliation(s)
- Erin Walch
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, United States
- Center for Glial-Neuronal Interactions, University of California, Riverside, Riverside, United States
| | - Thomas R. Murphy
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, United States
| | - Nicholas Cuvelier
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, United States
- Interdepartmental Graduate Program in Neuroscience, University of California, Riverside, Riverside, United States
| | - Murad Aldoghmi
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, United States
| | - Cristine Morozova
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, United States
- Undergraduate Major in Neuroscience, University of California, Riverside, Riverside, United States
| | - Jordan Donohue
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, United States
- Interdepartmental Graduate Program in Neuroscience, University of California, Riverside, Riverside, United States
| | - Gaby Young
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, United States
- Undergraduate Major in Neuroscience, University of California, Riverside, Riverside, United States
| | - Anuja Samant
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, United States
- Undergraduate Major in Neuroscience, University of California, Riverside, Riverside, United States
| | - Stacy Garcia
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, United States
- Undergraduate Major in Neuroscience, University of California, Riverside, Riverside, United States
| | - Camila Alvarez
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, United States
- Undergraduate Major in Neuroscience, University of California, Riverside, Riverside, United States
| | - Alex Bilas
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, United States
- Interdepartmental Graduate Program in Neuroscience, University of California, Riverside, Riverside, United States
| | - David Davila
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, United States
| | - Devin K. Binder
- Division of Biomedical Sciences, School of Medicine, University of California, Riverside, Riverside, United States
- Center for Glial-Neuronal Interactions, University of California, Riverside, Riverside, United States
- Interdepartmental Graduate Program in Neuroscience, University of California, Riverside, Riverside, United States
| | - Todd A. Fiacco
- Center for Glial-Neuronal Interactions, University of California, Riverside, Riverside, United States
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, Riverside, United States
- Interdepartmental Graduate Program in Neuroscience, University of California, Riverside, Riverside, United States
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