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MacAulay N, Toft-Bertelsen TL. Dual function of the choroid plexus: Cerebrospinal fluid production and control of brain ion homeostasis. Cell Calcium 2023; 116:102797. [PMID: 37801806 DOI: 10.1016/j.ceca.2023.102797] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 09/07/2023] [Accepted: 09/08/2023] [Indexed: 10/08/2023]
Abstract
The choroid plexus is a small monolayered epithelium located in the brain ventricles and serves to secrete the cerebrospinal fluid (CSF) that envelops the brain and fills the central ventricles. The CSF secretion is sustained with a concerted effort of a range of membrane transporters located in a polarized fashion in this tissue. Prominent amongst these are the Na+/K+-ATPase, the Na+,K+,2Cl- cotransporter (NKCC1), and several HCO3- transporters, which together support the net transepithelial transport of the major electrolytes, Na+ and Cl-, and thus drive the CSF secretion. The choroid plexus, in addition, serves an important role in keeping the CSF K+ concentration at a level compatible with normal brain function. The choroid plexus Na+/K+-ATPase represents a key factor in the barrier-mediated control of the CSF K+ homeostasis, as it increases its K+ uptake activity when faced with elevated extracellular K+ ([K+]o). In certain developmental or pathological conditions, the NKCC1 may revert its net transport direction to contribute to CSF K+ homeostasis. The choroid plexus ion transport machinery thus serves dual, yet interconnected, functions with its contribution to electrolyte and fluid secretion in combination with its control of brain K+ levels.
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Affiliation(s)
- Nanna MacAulay
- Department of Neuroscience, University of Copenhagen, Blegdamsvej 3, Copenhagen 2200, Denmark.
| | - Trine L Toft-Bertelsen
- Department of Neuroscience, University of Copenhagen, Blegdamsvej 3, Copenhagen 2200, Denmark
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2
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Xiang J, Hua Y, Xi G, Keep RF. Mechanisms of cerebrospinal fluid and brain interstitial fluid production. Neurobiol Dis 2023; 183:106159. [PMID: 37209923 PMCID: PMC11071066 DOI: 10.1016/j.nbd.2023.106159] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 05/16/2023] [Accepted: 05/17/2023] [Indexed: 05/22/2023] Open
Abstract
Fluid homeostasis is fundamental for brain function with cerebral edema and hydrocephalus both being major neurological conditions. Fluid movement from blood into brain is one crucial element in cerebral fluid homeostasis. Traditionally it has been thought to occur primarily at the choroid plexus (CP) as cerebrospinal fluid (CSF) secretion due to polarized distribution of ion transporters at the CP epithelium. However, there are currently controversies as to the importance of the CP in fluid secretion, just how fluid transport occurs at that epithelium versus other sites, as well as the direction of fluid flow in the cerebral ventricles. The purpose of this review is to evaluate evidence on the movement of fluid from blood to CSF at the CP and the cerebral vasculature and how this differs from other tissues, e.g., how ion transport at the blood-brain barrier as well as the CP may drive fluid flow. It also addresses recent promising data on two potential targets for modulating CP fluid secretion, the Na+/K+/Cl- cotransporter, NKCC1, and the non-selective cation channel, transient receptor potential vanilloid 4 (TRPV4). Finally, it raises the issue that fluid secretion from blood is not constant, changing with disease and during the day. The apparent importance of NKCC1 phosphorylation and TRPV4 activity at the CP in determining fluid movement suggests that such secretion may also vary over short time frames. Such dynamic changes in CP (and potentially blood-brain barrier) function may contribute to some of the controversies over its role in brain fluid secretion.
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Affiliation(s)
- Jianming Xiang
- Department of Neurosurgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ya Hua
- Department of Neurosurgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - Guohua Xi
- Department of Neurosurgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - Richard F Keep
- Department of Neurosurgery, University of Michigan, Ann Arbor, MI 48109, USA.
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3
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Fame RM, Xu H, Pragana A, Lehtinen M. Age-appropriate potassium clearance from perinatal cerebrospinal fluid depends on choroid plexus NKCC1. Fluids Barriers CNS 2023; 20:45. [PMID: 37328833 PMCID: PMC10276483 DOI: 10.1186/s12987-023-00438-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 05/06/2023] [Indexed: 06/18/2023] Open
Abstract
Regulation of the volume and electrolyte composition of the cerebrospinal fluid (CSF) is vital for brain development and function. The Na-K-Cl co-transporter NKCC1 in the choroid plexus (ChP) plays key roles in regulating CSF volume by co-transporting ions and mediating same-direction water movements. Our previous study showed ChP NKCC1 is highly phosphorylated in neonatal mice as the CSF K+ level drastically decreases and that overexpression of NKCC1 in the ChP accelerates CSF K+ clearance and reduces ventricle size [1]. These data suggest that NKCC1 mediates CSF K+ clearance following birth in mice. In this current study, we used CRISPR technology to create a conditional NKCC1 knockout mouse line and evaluated CSF K+ by Inductively Coupled Plasma Optical Emission spectroscopy (ICP-OES). We demonstrated ChP-specific reduction of total and phosphorylated NKCC1 in neonatal mice following embryonic intraventricular delivery of Cre recombinase using AAV2/5. ChP-NKCC1 knockdown was accompanied by a delayed perinatal clearance of CSF K+. No gross morphological disruptions were observed in the cerebral cortex. We extended our previous results by showing embryonic and perinatal rats shared key characteristics with mice, including decreased ChP NKCC1 expression level, increased ChP NKCC1 phosphorylation state, and increased CSF K+ levels compared to adult. Collectively, these follow up data support ChP NKCC1's role in age-appropriate CSF K+ clearance during neonatal development.
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Affiliation(s)
- Ryann M Fame
- Department of Pathology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA
- Present Address: Department of Neurosurgery, Stanford University, Stanford, CA, 94305, USA
| | - Huixin Xu
- Department of Pathology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Aja Pragana
- Department of Pathology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA
| | - Maria Lehtinen
- Department of Pathology, Boston Children's Hospital, Harvard Medical School, Boston, MA, 02115, USA.
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4
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Blazer-Yost BL. Consideration of Kinase Inhibitors for the Treatment of Hydrocephalus. Int J Mol Sci 2023; 24:ijms24076673. [PMID: 37047646 PMCID: PMC10094860 DOI: 10.3390/ijms24076673] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/27/2023] [Accepted: 03/29/2023] [Indexed: 04/07/2023] Open
Abstract
Hydrocephalus is a devastating condition characterized by excess cerebrospinal fluid (CSF) in the brain. Currently, the only effective treatment is surgical intervention, usually involving shunt placement, a procedure prone to malfunction, blockage, and infection that requires additional, often repetitive, surgeries. There are no long-term pharmaceutical treatments for hydrocephalus. To initiate an intelligent drug design, it is necessary to understand the biochemical changes underlying the pathology of this chronic condition. One potential commonality in the various forms of hydrocephalus is an imbalance in fluid–electrolyte homeostasis. The choroid plexus, a complex tissue found in the brain ventricles, is one of the most secretory tissues in the body, producing approximately 500 mL of CSF per day in an adult human. In this manuscript, two key transport proteins of the choroid plexus epithelial cells, transient receptor potential vanilloid 4 and sodium, potassium, 2 chloride co-transporter 1, will be considered. Both appear to play key roles in CSF production, and their inhibition or genetic manipulation has been shown to affect CSF volume. As with most transporters, these proteins are regulated by kinases. Therefore, specific kinase inhibitors are also potential targets for the development of pharmaceuticals to treat hydrocephalus.
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Affiliation(s)
- Bonnie L. Blazer-Yost
- Biology Department, Indiana University—Purdue University, 723 West Michigan Street, Indianapolis, IN 46202, USA
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5
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Karimy JK, Newville JC, Sadegh C, Morris JA, Monuki ES, Limbrick DD, McAllister Ii JP, Koschnitzky JE, Lehtinen MK, Jantzie LL. Outcomes of the 2019 hydrocephalus association workshop, "Driving common pathways: extending insights from posthemorrhagic hydrocephalus". Fluids Barriers CNS 2023; 20:4. [PMID: 36639792 PMCID: PMC9838022 DOI: 10.1186/s12987-023-00406-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Accepted: 01/05/2023] [Indexed: 01/15/2023] Open
Abstract
The Hydrocephalus Association (HA) workshop, Driving Common Pathways: Extending Insights from Posthemorrhagic Hydrocephalus, was held on November 4 and 5, 2019 at Washington University in St. Louis. The workshop brought together a diverse group of basic, translational, and clinical scientists conducting research on multiple hydrocephalus etiologies with select outside researchers. The main goals of the workshop were to explore areas of potential overlap between hydrocephalus etiologies and identify drug targets that could positively impact various forms of hydrocephalus. This report details the major themes of the workshop and the research presented on three cell types that are targets for new hydrocephalus interventions: choroid plexus epithelial cells, ventricular ependymal cells, and immune cells (macrophages and microglia).
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Affiliation(s)
- Jason K Karimy
- Department of Family Medicine, Mountain Area Health Education Center - Boone, North Carolina, 28607, USA
| | - Jessie C Newville
- Department of Pediatrics and Neurosurgery, Johns Hopkins Children's Center, Johns Hopkins School of Medicine, Baltimore, MD, 21287, USA
| | - Cameron Sadegh
- Department of Neurosurgery, Massachusetts General Hospital and Harvard Medical School, MA, Boston, 02114, USA
- Department of Pathology, Boston Children's Hospital, Boston, MA, 02115, USA
| | - Jill A Morris
- National Institute of Neurological Disorders and Stroke, Neuroscience Center, National Institutes of Health, 6001 Executive Blvd, NSC Rm 2112, Bethesda, MD, 20892, USA
| | - Edwin S Monuki
- Departments of Pathology & Laboratory Medicine and Developmental & Cell Biology, University of California Irvine, Irvine, CA, 92697, USA
| | - David D Limbrick
- Departments of Neurosurgery and Pediatrics, Washington University School of Medicine in St. Louis, St. Louis, MO, 63110, USA
| | - James P McAllister Ii
- Departments of Neurosurgery and Pediatrics, Washington University School of Medicine in St. Louis, St. Louis, MO, 63110, USA
| | | | - Maria K Lehtinen
- Department of Pathology, Boston Children's Hospital, Boston, MA, 02115, USA.
| | - Lauren L Jantzie
- Department of Pediatrics and Neurosurgery, Johns Hopkins Children's Center, Johns Hopkins School of Medicine, Baltimore, MD, 21287, USA.
- Kennedy Krieger Institute, Baltimore, MD, 21287, USA.
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6
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Saunders NR, Dziegielewska KM, Fame RM, Lehtinen MK, Liddelow SA. The choroid plexus: a missing link in our understanding of brain development and function. Physiol Rev 2023; 103:919-956. [PMID: 36173801 PMCID: PMC9678431 DOI: 10.1152/physrev.00060.2021] [Citation(s) in RCA: 25] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 09/01/2022] [Accepted: 09/17/2022] [Indexed: 11/22/2022] Open
Abstract
Studies of the choroid plexus lag behind those of the more widely known blood-brain barrier, despite a much longer history. This review has two overall aims. The first is to outline long-standing areas of research where there are unanswered questions, such as control of cerebrospinal fluid (CSF) secretion and blood flow. The second aim is to review research over the past 10 years where the focus has shifted to the idea that there are choroid plexuses located in each of the brain's ventricles that make specific contributions to brain development and function through molecules they generate for delivery via the CSF. These factors appear to be particularly important for aspects of normal brain growth. Most research carried out during the twentieth century dealt with the choroid plexus, a brain barrier interface making critical contributions to the composition and stability of the brain's internal environment throughout life. More recent research in the twenty-first century has shown the importance of choroid plexus-generated CSF in neurogenesis, influence of sex and other hormones on choroid plexus function, and choroid plexus involvement in circadian rhythms and sleep. The advancement of technologies to facilitate delivery of brain-specific therapies via the CSF to treat neurological disorders is a rapidly growing area of research. Conversely, understanding the basic mechanisms and implications of how maternal drug exposure during pregnancy impacts the developing brain represents another key area of research.
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Affiliation(s)
- Norman R Saunders
- Department of Neuroscience, The Alfred Centre, Monash University, Melbourne, Victoria, Australia
| | | | - Ryann M Fame
- Department of Pathology, Boston Children's Hospital, Boston, Massachusetts
| | - Maria K Lehtinen
- Department of Pathology, Boston Children's Hospital, Boston, Massachusetts
| | - Shane A Liddelow
- Neuroscience Institute, NYU Grossman School of Medicine, New York, New York
- Department of Neuroscience and Physiology, NYU Grossman School of Medicine, New York, New York
- Department of Ophthalmology, NYU Grossman School of Medicine, New York, New York
- Parekh Center for Interdisciplinary Neurology, NYU Grossman School of Medicine, New York, New York
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Huang B, Wang H, Yang B. Non-Aquaporin Water Channels. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1398:331-342. [PMID: 36717505 DOI: 10.1007/978-981-19-7415-1_23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Water transport through membrane is so intricate that there are still some debates. AQPs are entirely accepted to allow water transmembrane movement depending on osmotic gradient. Cotransporters and uniporters, however, are also concerned in water homeostasis. UT-B has a single-channel water permeability that is similar to AQP1. CFTR was initially thought as a water channel but now not believed to transport water directly. By cotransporters, such as KCC4, NKCC1, SGLT1, GAT1, EAAT1, and MCT1, water is transported by water osmosis coupling with substrates, which explains how water is transported across the isolated small intestine. This chapter provides information about water transport mediated by other membrane proteins except AQPs.
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Affiliation(s)
- Boyue Huang
- Laboratory of Neuroscience and Tissue Engineering, Department of Anatomy, Basic Medical College, Chongqing Medical University, Chongqing, China
| | - Hongkai Wang
- Northwestern University Interdepartmental Neuroscience Program, Chicago, IL, USA
- Laboratory of Regenerative Rehabilitation and Department of Physical Medicine and Rehabilitation, Shirley Ryan AbilityLab and Northwestern University Feinberg School of Medicine and Shirley Ryan AbilityLab, Chicago, IL, USA
| | - Baoxue Yang
- School of Basic Medical Sciences, Peking University, Beijing, China.
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Wang L, Geng G, Zhu T, Chen W, Li X, Gu J, Jiang E. Progress in Research on TLR4-Mediated Inflammatory Response Mechanisms in Brain Injury after Subarachnoid Hemorrhage. Cells 2022; 11:cells11233781. [PMID: 36497041 PMCID: PMC9740134 DOI: 10.3390/cells11233781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022] Open
Abstract
Subarachnoid hemorrhage (SAH) is one of the common clinical neurological emergencies. Its incidence accounts for about 5-9% of cerebral stroke patients. Even surviving patients often suffer from severe adverse prognoses such as hemiplegia, aphasia, cognitive dysfunction and even death. Inflammatory response plays an important role during early nerve injury in SAH. Toll-like receptors (TLRs), pattern recognition receptors, are important components of the body's innate immune system, and they are usually activated by damage-associated molecular pattern molecules. Studies have shown that with TLR 4 as an essential member of the TLRs family, the inflammatory transduction pathway mediated by it plays a vital role in brain injury after SAH. After SAH occurrence, large amounts of blood enter the subarachnoid space. This can produce massive damage-associated molecular pattern molecules that bind to TLR4, which activates inflammatory response and causes early brain injury, thus resulting in serious adverse prognoses. In this paper, the process in research on TLR4-mediated inflammatory response mechanism in brain injury after SAH was reviewed to provide a new thought for clinical treatment.
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Affiliation(s)
- Lintao Wang
- Institute of Nursing and Health, Henan University, Kaifeng 475004, China
- School of Clinical Medicine, Henan University, Kaifeng 475004, China
- Department of Neurology, The First Affiliated Hospital of Henan University, Kaifeng 475001, China
| | - Guangping Geng
- Henan Technician College of Medicine and Health, Kaifeng 475000, China
| | - Tao Zhu
- Department of Geriatrics, Kaifeng Traditional Chinese Medicine Hospital, Kaifeng 475001, China
| | - Wenwu Chen
- Department of Neurology, The First Affiliated Hospital of Henan University, Kaifeng 475001, China
| | - Xiaohui Li
- Department of Neurology, The First Affiliated Hospital of Henan University, Kaifeng 475001, China
| | - Jianjun Gu
- Department of Neurosurgery, Henan Provincial People’s Hospital, Zhengzhou 450003, China
| | - Enshe Jiang
- Institute of Nursing and Health, Henan University, Kaifeng 475004, China
- Henan International Joint Laboratory for Nuclear Protein Regulation, Henan University, Kaifeng 475004, China
- Correspondence:
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9
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Blazer-Yost BL. Following Ussing's legacy: from amphibian models to mammalian kidney and brain. Am J Physiol Cell Physiol 2022; 323:C1061-C1069. [PMID: 36036449 PMCID: PMC9529261 DOI: 10.1152/ajpcell.00303.2022] [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: 07/12/2022] [Revised: 08/17/2022] [Accepted: 08/19/2022] [Indexed: 11/22/2022]
Abstract
Professor Hans H. Ussing (1911-2000) was one of the founding members of the field of epithelial cell biology. He is most famous for the electrophysiological technique that he developed to measure electrogenic ion flux across epithelial tissues. Ussing-style electrophysiology has been applied to multiple tissues and has informed fields as diverse as amphibian biology and medicine. In the latter, this technique has contributed to a basic understanding of maladies such as hypertension, polycystic kidney disease, cystic fibrosis, and diarrheal diseases to mention but a few. In addition to this valuable contribution to biological methods, Prof. Ussing also provided strong evidence for the concept of active transport several years before the elucidation of Na+K+ATPase. In addition, he provided cell biologists with the important concept of polarized epithelia with specific and different transporters found in the apical and basolateral membranes, thus providing these cells with the ability to conduct directional, active and passive transepithelial transport. My studies have used Ussing chamber electrophysiology to study the toad urinary bladder, an amphibian cell line, renal cell lines, and, most recently, choroid plexus cell lines. This technique has formed the basis of our in vitro mechanistic studies that are used in an iterative manner with animal models to better understand disease progress and treatment. I was honored to be invited to deliver the 2022 Hans Ussing Lecture sponsored by the Epithelial Transport Group of the American Physiological Society. This manuscript is a version of the material presented in that lecture.
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Affiliation(s)
- Bonnie L Blazer-Yost
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, Indiana
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Oernbo EK, Steffensen AB, Razzaghi Khamesi P, Toft-Bertelsen TL, Barbuskaite D, Vilhardt F, Gerkau NJ, Tritsaris K, Simonsen AH, Lolansen SD, Andreassen SN, Hasselbalch SG, Zeuthen T, Rose CR, Kurtcuoglu V, MacAulay N. Membrane transporters control cerebrospinal fluid formation independently of conventional osmosis to modulate intracranial pressure. Fluids Barriers CNS 2022; 19:65. [PMID: 36038945 PMCID: PMC9422132 DOI: 10.1186/s12987-022-00358-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 07/13/2022] [Indexed: 11/23/2022] Open
Abstract
Background Disturbances in the brain fluid balance can lead to life-threatening elevation in the intracranial pressure (ICP), which represents a vast clinical challenge. Nevertheless, the details underlying the molecular mechanisms governing cerebrospinal fluid (CSF) secretion are largely unresolved, thus preventing targeted and efficient pharmaceutical therapy of cerebral pathologies involving elevated ICP. Methods Experimental rats were employed for in vivo determinations of CSF secretion rates, ICP, blood pressure and ex vivo excised choroid plexus for morphological analysis and quantification of expression and activity of various transport proteins. CSF and blood extractions from rats, pigs, and humans were employed for osmolality determinations and a mathematical model employed to determine a contribution from potential local gradients at the surface of choroid plexus. Results We demonstrate that CSF secretion can occur independently of conventional osmosis and that local osmotic gradients do not suffice to support CSF secretion. Instead, the CSF secretion across the luminal membrane of choroid plexus relies approximately equally on the Na+/K+/2Cl− cotransporter NKCC1, the Na+/HCO3− cotransporter NBCe2, and the Na+/K+-ATPase, but not on the Na+/H+ exchanger NHE1. We demonstrate that pharmacological modulation of CSF secretion directly affects the ICP. Conclusions CSF secretion appears to not rely on conventional osmosis, but rather occur by a concerted effort of different choroidal transporters, possibly via a molecular mode of water transport inherent in the proteins themselves. Therapeutic modulation of the rate of CSF secretion may be employed as a strategy to modulate ICP. These insights identify new promising therapeutic targets against brain pathologies associated with elevated ICP. Supplementary Information The online version contains supplementary material available at 10.1186/s12987-022-00358-4.
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Affiliation(s)
- Eva K Oernbo
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Annette B Steffensen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Pooya Razzaghi Khamesi
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Trine L Toft-Bertelsen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Dagne Barbuskaite
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Frederik Vilhardt
- Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Niklas J Gerkau
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, 40225, Düsseldorf, Germany
| | - Katerina Tritsaris
- Department of Cellular and Molecular Medicine, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Anja H Simonsen
- Danish Dementia Research Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Sara D Lolansen
- 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
| | - Steen G Hasselbalch
- Danish Dementia Research Centre, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Zeuthen
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
| | - Christine R Rose
- Institute of Neurobiology, Heinrich Heine University Düsseldorf, Universitätsstrasse 1, 40225, Düsseldorf, Germany
| | - Vartan Kurtcuoglu
- Institute of Physiology, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
| | - Nanna MacAulay
- Department of Neuroscience, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark.
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Xu H, Miyajima M, Nakajima M, Ogino I, Kawamura K, Akiba C, Kamohara C, Sakamoto K, Karagiozov K, Nakamura E, Tada N, Arai H, Kondo A. Ptpn20 deletion in H-Tx rats enhances phosphorylation of the NKCC1 cotransporter in the choroid plexus: an evidence of genetic risk for hydrocephalus in an experimental study. Fluids Barriers CNS 2022; 19:39. [PMID: 35658898 PMCID: PMC9164390 DOI: 10.1186/s12987-022-00341-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 05/16/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Congenital hydrocephalus occurs with some inheritable characteristics, but the mechanisms of its development remain poorly understood. Animal models provide the opportunity to identify potential genetic causes in this condition. The Hydrocephalus-Texas (H-Tx) rat strain is one of the most studied animal models for investigating the causative genetic alterations and analyzing downstream pathogenetic mechanisms of congenital hydrocephalus. METHODS Comparative genomic hybridization (CGH) array on non-hydrocephalic and hydrocephalic H-Tx rats was used to identify causative genes of hydrocephalus. Targeted gene knockout mice were generated by CRISPR/Cas9 to study the role of this gene in hydrocephalus. RESULTS CGH array revealed a copy number loss in chromosome 16p16 region in hydrocephalic H-Tx rats at 18 days gestation, encompassing the protein tyrosine phosphatase non-receptor type 20 (Ptpn20), a non-receptor tyrosine phosphatase, without change in most non-hydrocephalic H-Tx rats. Ptpn20-knockout (Ptpn20-/-) mice were generated and found to develop ventriculomegaly at 8 weeks. Furthermore, high expression of phosphorylated Na-K-Cl cotransporter 1 (pNKCC1) was identified in the choroid plexus (CP) epithelium of mice lacking Ptpn20 from 8 weeks until 72 weeks. CONCLUSIONS This study determined the chromosomal location of the hydrocephalus-associated Ptpn20 gene in hydrocephalic H-Tx rats. The high level of pNKCC1 mediated by Ptpn20 deletion in CP epithelium may cause overproduction of cerebrospinal fluid and contribute to the formation of hydrocephalus in Ptpn20-/- mice. Ptpn20 may be a potential therapeutic target in the treatment of hydrocephalus.
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Affiliation(s)
- Hanbing Xu
- Department of Neurosurgery, Juntendo University Graduate School of Medicine, Hongo Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Masakazu Miyajima
- Department of Neurosurgery, Juntendo Tokyo Koto Geriatric Medical Center, 3-3-20 Shinsuna, Koto-ku, Tokyo, 136-0075, Japan.
| | - Madoka Nakajima
- Department of Neurosurgery, Juntendo University Graduate School of Medicine, Hongo Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Ikuko Ogino
- Department of Neurosurgery, Juntendo University Graduate School of Medicine, Hongo Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Kaito Kawamura
- Department of Neurosurgery, Juntendo University Graduate School of Medicine, Hongo Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Chihiro Akiba
- Department of Neurosurgery, Juntendo Tokyo Koto Geriatric Medical Center, 3-3-20 Shinsuna, Koto-ku, Tokyo, 136-0075, Japan
| | - Chihiro Kamohara
- Department of Neurosurgery, Juntendo University Graduate School of Medicine, Hongo Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Koichiro Sakamoto
- Department of Neurosurgery, Juntendo University Graduate School of Medicine, Hongo Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Kostadin Karagiozov
- Department of Neurosurgery, Juntendo University Graduate School of Medicine, Hongo Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Eri Nakamura
- Department of Genetic Analysis Model Laboratory, Juntendo University Graduate School of Medicine, Hongo Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Nobuhiro Tada
- Department of Genetic Analysis Model Laboratory, Juntendo University Graduate School of Medicine, Hongo Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Hajime Arai
- Department of Neurosurgery, Juntendo University Graduate School of Medicine, Hongo Bunkyo-ku, Tokyo, 113-8421, Japan
| | - Akihide Kondo
- Department of Neurosurgery, Juntendo University Graduate School of Medicine, Hongo Bunkyo-ku, Tokyo, 113-8421, Japan
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12
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Abstract
The brain harbors a unique ability to, figuratively speaking, shift its gears. During wakefulness, the brain is geared fully toward processing information and behaving, while homeostatic functions predominate during sleep. The blood-brain barrier establishes a stable environment that is optimal for neuronal function, yet the barrier imposes a physiological problem; transcapillary filtration that forms extracellular fluid in other organs is reduced to a minimum in brain. Consequently, the brain depends on a special fluid [the cerebrospinal fluid (CSF)] that is flushed into brain along the unique perivascular spaces created by astrocytic vascular endfeet. We describe this pathway, coined the term glymphatic system, based on its dependency on astrocytic vascular endfeet and their adluminal expression of aquaporin-4 water channels facing toward CSF-filled perivascular spaces. Glymphatic clearance of potentially harmful metabolic or protein waste products, such as amyloid-β, is primarily active during sleep, when its physiological drivers, the cardiac cycle, respiration, and slow vasomotion, together efficiently propel CSF inflow along periarterial spaces. The brain's extracellular space contains an abundance of proteoglycans and hyaluronan, which provide a low-resistance hydraulic conduit that rapidly can expand and shrink during the sleep-wake cycle. We describe this unique fluid system of the brain, which meets the brain's requisites to maintain homeostasis similar to peripheral organs, considering the blood-brain-barrier and the paths for formation and egress of the CSF.
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Affiliation(s)
- Martin Kaag Rasmussen
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Humberto Mestre
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark
- Center for Translational Neuromedicine, University of Rochester Medical Center, Rochester, New York
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13
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MacAulay N, Keep RF, Zeuthen T. Cerebrospinal fluid production by the choroid plexus: a century of barrier research revisited. Fluids Barriers CNS 2022; 19:26. [PMID: 35317823 PMCID: PMC8941821 DOI: 10.1186/s12987-022-00323-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 03/09/2022] [Indexed: 12/20/2022] Open
Abstract
Cerebrospinal fluid (CSF) envelops the brain and fills the central ventricles. This fluid is continuously replenished by net fluid extraction from the vasculature by the secretory action of the choroid plexus epithelium residing in each of the four ventricles. We have known about these processes for more than a century, and yet the molecular mechanisms supporting this fluid secretion remain unresolved. The choroid plexus epithelium secretes its fluid in the absence of a trans-epithelial osmotic gradient, and, in addition, has an inherent ability to secrete CSF against an osmotic gradient. This paradoxical feature is shared with other 'leaky' epithelia. The assumptions underlying the classical standing gradient hypothesis await experimental support and appear to not suffice as an explanation of CSF secretion. Here, we suggest that the elusive local hyperosmotic compartment resides within the membrane transport proteins themselves. In this manner, the battery of plasma membrane transporters expressed in choroid plexus are proposed to sustain the choroidal CSF secretion independently of the prevailing bulk osmotic gradient.
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Affiliation(s)
- Nanna MacAulay
- Department of Neuroscience, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark.
| | - Richard F Keep
- Department of Neurosurgery, University of Michigan, Ann Arbor, MI, USA
| | - Thomas Zeuthen
- Department of Neuroscience, University of Copenhagen, Blegdamsvej 3, 2200, Copenhagen, Denmark
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14
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Deffner F, Gleiser C, Mattheus U, Wagner A, Neckel PH, Fallier-Becker P, Hirt B, Mack AF. Aquaporin-4 expression in the human choroid plexus. Cell Mol Life Sci 2022; 79:90. [PMID: 35072772 PMCID: PMC8785037 DOI: 10.1007/s00018-022-04136-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Revised: 01/02/2022] [Accepted: 01/05/2022] [Indexed: 01/15/2023]
Abstract
The choroid plexus (CP) consists of specialized ependymal cells and underlying blood vessels and stroma producing the bulk of the cerebrospinal fluid (CSF). CP epithelial cells are considered the site of the internal blood-cerebrospinal fluid barrier, show epithelial characteristics (basal lamina, tight junctions), and express aquaporin-1 (AQP1) apically. In this study, we analyzed the expression of aquaporins in the human CP using immunofluorescence and qPCR. As previously reported, AQP1 was expressed apically in CP epithelial cells. Surprisingly, and previously unknown, many cells in the CP epithelium were also positive for aquaporin-4 (AQP4), normally restricted to ventricle-lining ependymal cells and astrocytes in the brain. Expression of AQP1 and AQP4 was found in the CP of all eight body donors investigated (3 males, 5 females; age 74–91). These results were confirmed by qPCR, and by electron microscopy detecting orthogonal arrays of particles. To find out whether AQP4 expression correlated with the expression pattern of relevant transport-related proteins we also investigated expression of NKCC1, and Na/K-ATPase. Immunostaining with NKCC1 was similar to AQP1 and revealed no particular pattern related to AQP4. Co-staining of AQP4 and Na/K-ATPase indicated a trend for an inverse correlation of their expression. We hypothesized that AQP4 expression in the CP was caused by age-related changes. To address this, we investigated mouse brains from young (2 months), adult (12 months) and old (30 months) mice. We found a significant increase of AQP4 on the mRNA level in old mice compared to young and adult animals. Taken together, we provide evidence for AQP4 expression in the CP of the aging brain which likely contributes to the water flow through the CP epithelium and CSF production. In two alternative hypotheses, we discuss this as a beneficial compensatory, or a detrimental mechanism influencing the previously observed CSF changes during aging.
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Affiliation(s)
- Felix Deffner
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Österbergstr. 3, 72074, Tübingen, Germany
| | - Corinna Gleiser
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Österbergstr. 3, 72074, Tübingen, Germany
| | - Ulrich Mattheus
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Österbergstr. 3, 72074, Tübingen, Germany
| | - Andreas Wagner
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Österbergstr. 3, 72074, Tübingen, Germany
| | - Peter H Neckel
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Österbergstr. 3, 72074, Tübingen, Germany
| | - Petra Fallier-Becker
- Institute of Pathology and Neuropathology, University of Tübingen, Tübingen, Germany
| | - Bernhard Hirt
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Österbergstr. 3, 72074, Tübingen, Germany
| | - Andreas F Mack
- Institute of Clinical Anatomy and Cell Analysis, University of Tübingen, Österbergstr. 3, 72074, Tübingen, Germany.
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15
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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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Affiliation(s)
- Francisco J Alvarez-Leefmans
- Department of Pharmacology and Toxicology, Boonshoft School of Medicine, Wright State University, Dayton, OH, USA
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