1
|
Toader C, Tataru CP, Florian IA, Covache-Busuioc RA, Dumitrascu DI, Glavan LA, Costin HP, Bratu BG, Ciurea AV. From Homeostasis to Pathology: Decoding the Multifaceted Impact of Aquaporins in the Central Nervous System. Int J Mol Sci 2023; 24:14340. [PMID: 37762642 PMCID: PMC10531540 DOI: 10.3390/ijms241814340] [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: 09/02/2023] [Revised: 09/15/2023] [Accepted: 09/18/2023] [Indexed: 09/29/2023] Open
Abstract
Aquaporins (AQPs), integral membrane proteins facilitating selective water and solute transport across cell membranes, have been the focus of extensive research over the past few decades. Particularly noteworthy is their role in maintaining cellular homeostasis and fluid balance in neural compartments, as dysregulated AQP expression is implicated in various degenerative and acute brain pathologies. This article provides an exhaustive review on the evolutionary history, molecular classification, and physiological relevance of aquaporins, emphasizing their significance in the central nervous system (CNS). The paper journeys through the early studies of water transport to the groundbreaking discovery of Aquaporin 1, charting the molecular intricacies that make AQPs unique. It delves into AQP distribution in mammalian systems, detailing their selective permeability through permeability assays. The article provides an in-depth exploration of AQP4 and AQP1 in the brain, examining their contribution to fluid homeostasis. Furthermore, it elucidates the interplay between AQPs and the glymphatic system, a critical framework for waste clearance and fluid balance in the brain. The dysregulation of AQP-mediated processes in this system hints at a strong association with neurodegenerative disorders such as Parkinson's Disease, idiopathic normal pressure hydrocephalus, and Alzheimer's Disease. This relationship is further explored in the context of acute cerebral events such as stroke and autoimmune conditions such as neuromyelitis optica (NMO). Moreover, the article scrutinizes AQPs at the intersection of oncology and neurology, exploring their role in tumorigenesis, cell migration, invasiveness, and angiogenesis. Lastly, the article outlines emerging aquaporin-targeted therapies, offering a glimpse into future directions in combatting CNS malignancies and neurodegenerative diseases.
Collapse
Affiliation(s)
- Corneliu Toader
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (C.T.); (R.-A.C.-B.); (D.-I.D.); (L.A.G.); (H.P.C.); (B.-G.B.); (A.V.C.)
- Department of Vascular Neurosurgery, National Institute of Neurology and Neurovascular Diseases, 077160 Bucharest, Romania
| | - Calin Petru Tataru
- Department of Opthamology, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania
- Central Military Emergency Hospital “Dr. Carol Davila”, 010825 Bucharest, Romania
| | - Ioan-Alexandru Florian
- Department of Neurosciences, “Iuliu Hatieganu” University of Medicine and Pharmacy, 400012 Cluj-Napoca, Romania
| | - Razvan-Adrian Covache-Busuioc
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (C.T.); (R.-A.C.-B.); (D.-I.D.); (L.A.G.); (H.P.C.); (B.-G.B.); (A.V.C.)
| | - David-Ioan Dumitrascu
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (C.T.); (R.-A.C.-B.); (D.-I.D.); (L.A.G.); (H.P.C.); (B.-G.B.); (A.V.C.)
| | - Luca Andrei Glavan
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (C.T.); (R.-A.C.-B.); (D.-I.D.); (L.A.G.); (H.P.C.); (B.-G.B.); (A.V.C.)
| | - Horia Petre Costin
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (C.T.); (R.-A.C.-B.); (D.-I.D.); (L.A.G.); (H.P.C.); (B.-G.B.); (A.V.C.)
| | - Bogdan-Gabriel Bratu
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (C.T.); (R.-A.C.-B.); (D.-I.D.); (L.A.G.); (H.P.C.); (B.-G.B.); (A.V.C.)
| | - Alexandru Vlad Ciurea
- Department of Neurosurgery, “Carol Davila” University of Medicine and Pharmacy, 020021 Bucharest, Romania; (C.T.); (R.-A.C.-B.); (D.-I.D.); (L.A.G.); (H.P.C.); (B.-G.B.); (A.V.C.)
- Neurosurgery Department, Sanador Clinical Hospital, 010991 Bucharest, Romania
| |
Collapse
|
2
|
Pechlivanidou M, Xenou K, Tzanetakos D, Koutsos E, Stergiou C, Andreadou E, Voumvourakis K, Giannopoulos S, Kilidireas C, Tüzün E, Tsivgoulis G, Tzartos S, Tzartos J. Potential Role of Antibodies against Aquaporin-1 in Patients with Central Nervous System Demyelination. Int J Mol Sci 2023; 24:12982. [PMID: 37629163 PMCID: PMC10455752 DOI: 10.3390/ijms241612982] [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: 06/28/2023] [Revised: 08/09/2023] [Accepted: 08/17/2023] [Indexed: 08/27/2023] Open
Abstract
Aquaporins (AQPs; AQP0-AQP12) are water channels expressed in many and diverse cell types, participating in various functions of cells, tissues, and systems, including the central nervous system (CNS). AQP dysfunction and autoimmunity to AQPs are implicated in several diseases. The best-known example of autoimmunity against AQPs concerns the antibodies to AQP4 which are involved in the pathogenesis of neuromyelitis optica spectrum disorder (NMOSD), an autoimmune astrocytopathy, causing also CNS demyelination. The present review focuses on the discovery and the potential role of antibodies against AQP1 in the CNS, and their potential involvement in the pathophysiology of NMOSD. We describe (a) the several techniques developed for the detection of the AQP1-antibodies, with emphasis on methods that specifically identify antibodies targeting the extracellular domain of AQP1, i.e., those of potential pathogenic role, and (b) the available evidence supporting the pathogenic relevance of AQP1-antibodies in the NMOSD phenotype.
Collapse
Affiliation(s)
- Maria Pechlivanidou
- Tzartos NeuroDiagnostics, 11523 Athens, Greece; (M.P.); (K.X.); (E.K.); (C.S.); (S.T.)
| | - Konstantina Xenou
- Tzartos NeuroDiagnostics, 11523 Athens, Greece; (M.P.); (K.X.); (E.K.); (C.S.); (S.T.)
| | - Dimitrios Tzanetakos
- Second Department of Neurology ‘’Attikon’’ University Hospital, School of Medicine, National & Kapodistrian University of Athens, 12462 Athens, Greece; (D.T.); (K.V.); (S.G.); (G.T.)
| | - Emmanuel Koutsos
- Tzartos NeuroDiagnostics, 11523 Athens, Greece; (M.P.); (K.X.); (E.K.); (C.S.); (S.T.)
| | - Christos Stergiou
- Tzartos NeuroDiagnostics, 11523 Athens, Greece; (M.P.); (K.X.); (E.K.); (C.S.); (S.T.)
| | - Elisabeth Andreadou
- First Department of Neurology, ‘’Aiginiteion’’ University Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece; (E.A.); (C.K.)
| | - Konstantinos Voumvourakis
- Second Department of Neurology ‘’Attikon’’ University Hospital, School of Medicine, National & Kapodistrian University of Athens, 12462 Athens, Greece; (D.T.); (K.V.); (S.G.); (G.T.)
| | - Sotirios Giannopoulos
- Second Department of Neurology ‘’Attikon’’ University Hospital, School of Medicine, National & Kapodistrian University of Athens, 12462 Athens, Greece; (D.T.); (K.V.); (S.G.); (G.T.)
| | - Constantinos Kilidireas
- First Department of Neurology, ‘’Aiginiteion’’ University Hospital, National and Kapodistrian University of Athens, 11528 Athens, Greece; (E.A.); (C.K.)
- Second Department of Neurology, Henry Dunant Hospital Center, 11526 Athens, Greece
| | - Erdem Tüzün
- Department of Neuroscience, Aziz Sancar Institute of Experimental Medicine, Istanbul University, 34093 Istanbul, Turkey;
| | - Georgios Tsivgoulis
- Second Department of Neurology ‘’Attikon’’ University Hospital, School of Medicine, National & Kapodistrian University of Athens, 12462 Athens, Greece; (D.T.); (K.V.); (S.G.); (G.T.)
| | - Socrates Tzartos
- Tzartos NeuroDiagnostics, 11523 Athens, Greece; (M.P.); (K.X.); (E.K.); (C.S.); (S.T.)
- Department of Neurobiology, Hellenic Pasteur Institute, 11521 Athens, Greece
- Department of Pharmacy, University of Patras, 26504 Patras, Greece
| | - John Tzartos
- Second Department of Neurology ‘’Attikon’’ University Hospital, School of Medicine, National & Kapodistrian University of Athens, 12462 Athens, Greece; (D.T.); (K.V.); (S.G.); (G.T.)
| |
Collapse
|
3
|
Theologou M, Natsis K, Kouskouras K, Chatzinikolaou F, Varoutis P, Skoulios N, Tsitouras V, Tsonidis C. Cerebrospinal Fluid Homeostasis and Hydrodynamics: A Review of Facts and Theories. Eur Neurol 2022; 85:313-325. [PMID: 35405679 DOI: 10.1159/000523709] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 02/04/2022] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND PURPOSE According to the classical hypothesis, the cerebrospinal fluid (CSF) is actively secreted inside the brain's ventricular system, predominantly by the choroid plexuses, before flowing unidirectionally in a cranio-caudal orientation toward the arachnoid granulations (AGs), where it is reabsorbed into the dural venous sinuses. This concept has been accepted as a doctrine for more than 100 years and was subjected only to minor modifications. Its inability to provide an adequate explanation to questions arising from the everyday clinical practice, in addition to the ever growing pool of experimental data contradicting it, has led to the identification of its limitations. Literature includes an increasing number of studies suggesting a more complex mechanism than that previously described. This review article summarizes the proposed mechanisms of CSF regulation, referring to the key clinical and experimental developments supporting or defying them. METHODS A non-systematical literature search of the major databases was performed for studies on the mechanisms of CSF homeostasis. Gray literature was additionally assessed employing a hand-search technique. No restrictions were imposed regarding the time, language, or type of publication. CONCLUSION CSF secretion and absorption are expected to take place throughout the entire brain's capillaries network under the regulation of hydrostatic and osmotic gradients. The unidirectional flow is defied, highlighting the possibility of its complete absence. The importance of AGs is brought into question, potentiating the significance of the lymphatic system as the primary site of reabsorption. However, the definition of hydrocephalus and its treatment strategies remain strongly associated with the classical hypothesis.
Collapse
Affiliation(s)
- Marios Theologou
- Second Department of Neurosurgery, Aristotle University of Thessaloniki, General Hospital of Thessaloniki Hippokratio, Thessaloniki, Greece
| | - Konstantinos Natsis
- Department of Anatomy and Surgical Anatomy, School of Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Konstantinos Kouskouras
- Department of Radiology, AHEPA University Hospital, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Fotios Chatzinikolaou
- Department of Forensic Medicine and Toxicology, Medical School, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Panagiotis Varoutis
- Second Department of Neurosurgery, Aristotle University of Thessaloniki, General Hospital of Thessaloniki Hippokratio, Thessaloniki, Greece
| | - Nikolaos Skoulios
- Second Department of Neurosurgery, Aristotle University of Thessaloniki, General Hospital of Thessaloniki Hippokratio, Thessaloniki, Greece
| | - Vassilios Tsitouras
- Second Department of Neurosurgery, Aristotle University of Thessaloniki, General Hospital of Thessaloniki Hippokratio, Thessaloniki, Greece
| | - Christos Tsonidis
- Second Department of Neurosurgery, Aristotle University of Thessaloniki, General Hospital of Thessaloniki Hippokratio, Thessaloniki, Greece
| |
Collapse
|
4
|
Critical role of Aquaporin-1 and telocytes in infantile hemangioma response to propranolol beta blockade. Proc Natl Acad Sci U S A 2021; 118:2018690118. [PMID: 33558238 DOI: 10.1073/pnas.2018690118] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Propranolol, a nonselective β-adrenergic receptor (ADRB) antagonist, is the first-line therapy for severe infantile hemangiomas (IH). Since the incidental discovery of propranolol efficacy in IH, preclinical and clinical investigations have shown evidence of adjuvant propranolol response in some malignant tumors. However, the mechanism for propranolol antitumor effect is still largely unknown, owing to the absence of a tumor model responsive to propranolol at nontoxic concentrations. Immunodeficient mice engrafted with different human tumor cell lines were treated with anti-VEGF bevacizumab to create a model sensitive to propranolol. Proteomics analysis was used to reveal propranolol-mediated protein alteration correlating with tumor growth inhibition, and Aquaporin-1 (AQP1), a water channel modulated in tumor cell migration and invasion, was identified. IH tissues and cells were then functionally investigated. Our functional protein association networks analysis and knockdown of ADRB2 and AQP1 indicated that propranolol treatment and AQP1 down-regulation trigger the same pathway, suggesting that AQP1 is a major driver of beta-blocker antitumor response. Examining AQP1 in human hemangioma samples, we found it exclusively in a perivascular layer, so far unrecognized in IH, made of telocytes (TCs). Functional in vitro studies showed that AQP1-positive TCs play a critical role in IH response to propranolol and that modulation of AQP1 in IH-TC by propranolol or shAQP1 decreases capillary-like tube formation in a Matrigel-based angiogenesis assay. We conclude that IH sensitivity to propranolol may rely, at least in part, on a cross talk between lesional vascular cells and stromal TCs.
Collapse
|
5
|
Yao Y, Zhang Y, Liao X, Yang R, Lei Y, Luo J. Potential Therapies for Cerebral Edema After Ischemic Stroke: A Mini Review. Front Aging Neurosci 2021; 12:618819. [PMID: 33613264 PMCID: PMC7890111 DOI: 10.3389/fnagi.2020.618819] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2020] [Accepted: 12/28/2020] [Indexed: 02/05/2023] Open
Abstract
Stroke is the leading cause of global mortality and disability. Cerebral edema and intracranial hypertension are common complications of cerebral infarction and the major causes of mortality. The formation of cerebral edema includes three stages (cytotoxic edema, ionic edema, and vasogenic edema), which involve multiple proteins and ion channels. A range of therapeutic agents that successfully target cerebral edema have been developed in animal studies, some of which have been assessed in clinical trials. Herein, we review the mechanisms of cerebral edema and the research progress of anti-edema therapies for use after ischemic stroke.
Collapse
Affiliation(s)
- Yi Yao
- International Medical Center, Ward of General Practice and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Yonggang Zhang
- Department of Periodical Press and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
- Nursing Key Laboratory of Sichuan Province, Chengdu, China
- Chinese Evidence-Based Medicine Center, West China Hospital, Sichuan University, Chengdu, China
| | - Xiaoyang Liao
- International Medical Center, Ward of General Practice and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Rong Yang
- International Medical Center, Ward of General Practice and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Yi Lei
- International Medical Center, Ward of General Practice and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| | - Jianzhao Luo
- International Medical Center, Ward of General Practice and National Clinical Research Center for Geriatrics, West China Hospital, Sichuan University, Chengdu, China
| |
Collapse
|
6
|
Nosaka M, Ishida Y, Kuninaka Y, Ishigami A, Taruya A, Shimada E, Hashizume Y, Yamamoto H, Kimura A, Furukawa F, Kondo T. Intrathrombotic appearances of AQP-1 and AQP-3 in relation to thrombus age in murine deep vein thrombosis model. Int J Legal Med 2021; 135:547-553. [PMID: 33410924 PMCID: PMC7788166 DOI: 10.1007/s00414-020-02482-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 12/09/2020] [Indexed: 11/17/2022]
Abstract
Aquaporins (AQPs) are membrane-bound proteins for water transportation and are useful for diagnosing drowning and wound vitality in forensic pathology. Here, we examined intrathrombotic expression of AQP-1 and AQP-3 using deep vein thrombosis models in mice. To perform immunohistochemical analyses, we used anti-AQP-1 and anti-AQP-3 antibodies. In thrombus samples with the post-ligation intervals of 1 to 5 days, AQP-1+ areas were over 70%. At 7 days after the IVC ligation, AQP-1+ areas became less than 50%, eventually decreasing to 11% at 21 days. At 3 days after the IVC ligation, AQP-3+ cells started to appear from the peripheral area. Thereafter, the positive cell number progressively increased and reached to a peak at 10 days after the IVC ligation. When the intrathrombotic AQP-1+ area was as large as the intrathrombotic collagen area or smaller, it would indicate a thrombus age of ≥ 10 days. AQP-3+ cell number of > 30 would indicate a thrombus age of 10–14 days. Collectively, our study implied that the detection of AQP-1 and AQP-3 would be useful for the determination of thrombus age.
Collapse
Affiliation(s)
- Mizuho Nosaka
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Yuko Ishida
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Yumi Kuninaka
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Akiko Ishigami
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Akira Taruya
- Department of Cardiovascular Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Emi Shimada
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Yumiko Hashizume
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Hiroki Yamamoto
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Akihiko Kimura
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Fukumi Furukawa
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan.,Takatsuki Red Cross Hospital , 1-1-1 Abuno, Takatsuki, Osaka, 569-1096, Japan
| | - Toshikazu Kondo
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan.
| |
Collapse
|
7
|
Kadry H, Noorani B, Cucullo L. A blood-brain barrier overview on structure, function, impairment, and biomarkers of integrity. Fluids Barriers CNS 2020; 17:69. [PMID: 33208141 PMCID: PMC7672931 DOI: 10.1186/s12987-020-00230-3] [Citation(s) in RCA: 533] [Impact Index Per Article: 133.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Accepted: 11/07/2020] [Indexed: 02/07/2023] Open
Abstract
The blood–brain barrier is playing a critical role in controlling the influx and efflux of biological substances essential for the brain’s metabolic activity as well as neuronal function. Thus, the functional and structural integrity of the BBB is pivotal to maintain the homeostasis of the brain microenvironment. The different cells and structures contributing to developing this barrier are summarized along with the different functions that BBB plays at the brain–blood interface. We also explained the role of shear stress in maintaining BBB integrity. Furthermore, we elaborated on the clinical aspects that correlate between BBB disruption and different neurological and pathological conditions. Finally, we discussed several biomarkers that can help to assess the BBB permeability and integrity in-vitro or in-vivo and briefly explain their advantages and disadvantages.
Collapse
Affiliation(s)
- Hossam Kadry
- Department of Pharmaceutical Sciences, Jerry H. Hodge School of Pharmacy, Texas Tech University Health Sciences Center, 1300 S. Coulter Street, Amarillo, TX, 79106, USA
| | - Behnam Noorani
- Department of Pharmaceutical Sciences, Jerry H. Hodge School of Pharmacy, Texas Tech University Health Sciences Center, 1300 S. Coulter Street, Amarillo, TX, 79106, USA
| | - Luca Cucullo
- Dept. of Foundational Medical Studies, Oakland University William Beaumont School of Medicine, Office 415, Rochester, MI, 48309, USA.
| |
Collapse
|
8
|
Park SH, Lee JY, Jhee KH, Yang SA. Amyloid-ß peptides inhibit the expression of AQP4 and glutamate transporter EAAC1 in insulin-treated C6 glioma cells. Toxicol Rep 2020; 7:1083-1089. [PMID: 32953460 PMCID: PMC7484518 DOI: 10.1016/j.toxrep.2020.08.032] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 08/09/2020] [Accepted: 08/27/2020] [Indexed: 01/30/2023] Open
Abstract
Astrocytic aquaporin 4 (AQP4) facilitates glutamate clearance via regulation of the glutamate transporter function, involved in the modulation of brain plasticity and cognitive function to prevent neurodegenerative disorders such as Alzheimer's disease (AD). In in vitro studies, the C6 rat glioma cell line is a widely applied aging model system to investigate changes in glial cells associated with aging or AD. However, the neurotoxicity mechanism whether AQP4 mediate glutamate uptake in Aβ-stimulated C6 cell remain uncertain. In this study, we examined the effects of Aβ on the expression of AQP4, Glu transporters, Glu uptake, and cell viability in insulin-treated C6 cells. Our results showed that the expression of AQP4 mRNA and protein was significantly enhanced by insulin in older cultures (passage 45), and the expression was inhibited by Aβ at 10 μM. In addition, the cell viability and glutamate uptake in Aβ-treated C6 cells were decreased in dose-dependent manners. GFAP showed similar changes in gene and protein expression patterns as AQP4, but no significant alterations were seen in GLAST expression. In C6 cells, the glutamate transport was found to be EAAC1, not GLT-1. EAAC1 expression was decreased by the treatment of Aβ. Taken together, our findings suggest that C6 cells may have astrocytic characteristics, and the astrocytic cytotoxicity induced by Aβ was mediated by reduction of glutamate uptake through AQP4/EAAC1 pathway in C6 cells. This indicates that C6 glioma cells could be used to study the roles of AQP4 on astrocyte function in AD.
Collapse
Affiliation(s)
- Se-Ho Park
- Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea.,Institute of Natural Science, Keimyung University, Daegu 42601, Republic of Korea
| | - Jae-Yeul Lee
- Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea.,Institute of Natural Science, Keimyung University, Daegu 42601, Republic of Korea
| | - Kwang-Hwan Jhee
- Department of Applied Chemistry, Kumoh National Institute of Technology, Gumi 39177, Republic of Korea
| | - Seun-Ah Yang
- Department of Food Science and Technology, Keimyung University, Daegu 42601, Republic of Korea
| |
Collapse
|
9
|
Shamsaldeen YA, Lione LA, Benham CD. Dysregulation of TRPV4, eNOS and caveolin-1 contribute to endothelial dysfunction in the streptozotocin rat model of diabetes. Eur J Pharmacol 2020; 888:173441. [PMID: 32810492 DOI: 10.1016/j.ejphar.2020.173441] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/28/2020] [Accepted: 07/29/2020] [Indexed: 12/30/2022]
Abstract
Endothelial dysfunction is a common complication in diabetes in which endothelium-dependent vasorelaxation is impaired. The aim of this study was to examine the involvement of the TRPV4 ion channel in type 1 diabetic endothelial dysfunction and the possible association of endothelial dysfunction with reduced expression of TRPV4, endothelial nitric oxide synthase (eNOS) and caveolin-1. Male Wistar rats (350-450 g) were injected with 65 mg/kg i.p. streptozotocin (STZ) or vehicle. Endothelial function was investigated in aortic rings and mesenteric arteries using organ bath and myograph, respectively. TRPV4 function was studied with fura-2 calcium imaging in endothelial cells cultured from aortas from control and STZ treated rats. TRPV4, caveolin-1 and eNOS expression was investigated in these cells using immunohistochemistry. STZ-treated diabetic rats showed significant endothelial dysfunction characterised by impaired muscarinic-induced vasorelaxation (aortic rings: STZ-diabetics: Emax = 29.6 ± 9.3%; control: Emax = 77.2 ± 2.5% P˂0.001), as well as significant impairment in TRPV4-induced vasorelaxation (aortic rings, 4αPDD STZ-diabetics: Emax = 56.0 ± 5.5%; control: Emax = 81.1 ± 2.1% P˂0.001). Furthermore, STZ-diabetic primary aortic endothelial cells showed a significant reduction in TRPV4-induced intracellular calcium elevation (P˂0.05) compared with the control group. This was associated with significantly lower expression of TRPV4, caveolin-1 and eNOS and this was reversed by insulin treatment of the endothelial cultures from STZ -diabetic rats. Taken together, these data are consistent with the hypothesis that signalling through TRPV4, caveolin-1, and eNOS is downregulated in STZ-diabetic aortic endothelial cells and restored by insulin treatment.
Collapse
Affiliation(s)
- Yousif A Shamsaldeen
- School of Life and Medical Sciences, University of Hertfordshire, College Lane, Hatfield, Hertfordshire, AL10 9AB, UK; Department of Pharmacy, Kuwait Hospital, Sabah Alsalem, 44001, Kuwait.
| | - Lisa A Lione
- School of Life and Medical Sciences, University of Hertfordshire, College Lane, Hatfield, Hertfordshire, AL10 9AB, UK
| | - Christopher D Benham
- School of Life and Medical Sciences, University of Hertfordshire, College Lane, Hatfield, Hertfordshire, AL10 9AB, UK
| |
Collapse
|
10
|
Papadopoulos Z, Herz J, Kipnis J. Meningeal Lymphatics: From Anatomy to Central Nervous System Immune Surveillance. THE JOURNAL OF IMMUNOLOGY 2020; 204:286-293. [PMID: 31907271 DOI: 10.4049/jimmunol.1900838] [Citation(s) in RCA: 53] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 11/15/2019] [Indexed: 12/24/2022]
Abstract
At steady state, the CNS parenchyma has few to no lymphocytes and less potent Ag-presentation capability compared with other organs. However, the meninges surrounding the CNS host diverse populations of immune cells that influence how CNS-related immune responses develop. Interstitial and cerebrospinal fluid produced in the CNS is continuously drained, and recent advances have emphasized that this process is largely taking place through the lymphatic system. To what extent this fluid process mobilizes CNS-derived Ags toward meningeal immune cells and subsequently the peripheral immune system through the lymphatic vessel network is a question of significant clinical importance for autoimmunity, tumor immunology, and infectious disease. Recent advances in understanding the role of meningeal lymphatics as a communicator between the brain and peripheral immunity are discussed in this review.
Collapse
Affiliation(s)
- Zachary Papadopoulos
- Center for Brain Immunology and Glia, Neuroscience Graduate Program, Department of Neuroscience, University of Virginia, Charlottesville, VA 22908
| | - Jasmin Herz
- Center for Brain Immunology and Glia, Neuroscience Graduate Program, Department of Neuroscience, University of Virginia, Charlottesville, VA 22908
| | - Jonathan Kipnis
- Center for Brain Immunology and Glia, Neuroscience Graduate Program, Department of Neuroscience, University of Virginia, Charlottesville, VA 22908
| |
Collapse
|
11
|
Dasdelen D, Mogulkoc R, Baltaci AK. Aquaporins and Roles in Brain Health and Brain Injury. Mini Rev Med Chem 2020; 20:498-512. [DOI: 10.2174/1389557519666191018142007] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 05/07/2019] [Accepted: 10/03/2019] [Indexed: 02/08/2023]
Abstract
In the literature screening, aquaporins were found in the cerebral structures including the pia mater, choroid plexus, ependyma, piriform cortex, hippocampus, dorsal thalamus, supraoptic and suprachiasmatic nuclei, white matter and subcortical organ. Among these, the most common are AQP1, AQP4, and AQP9. The roles of aquaporins have been demonstrated in several diseases such as cerebral edema, various central nervous system tumors, Alzheimer’s Disease and epilepsy. In this review, the relationship between brain/brain-injury and aquaporin, has been reviewed.
Collapse
Affiliation(s)
- Dervis Dasdelen
- Department of Physiology, Medical Faculty, Selcuk University, Konya, Turkey
| | - Rasim Mogulkoc
- Department of Physiology, Medical Faculty, Selcuk University, Konya, Turkey
| | | |
Collapse
|
12
|
Fisher D, Mentor S. Are claudin-5 tight-junction proteins in the blood-brain barrier porous? Neural Regen Res 2020; 15:1838-1839. [PMID: 32246625 PMCID: PMC7513970 DOI: 10.4103/1673-5374.280308] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Affiliation(s)
- David Fisher
- Department of Medical Biosciences, University of the Western Cape, Bellville, Cape Town, South Africa; School of Health Professions, University of Missouri, Columbia, MO, USA
| | - Shireen Mentor
- Department of Medical Biosciences, University of the Western Cape, Bellville, Cape Town, South Africa
| |
Collapse
|
13
|
Chen CY, Liao PL, Tsai CH, Chan YJ, Cheng YW, Hwang LL, Lin KH, Yen TL, Li CH. Inhaled gold nanoparticles cause cerebral edema and upregulate endothelial aquaporin 1 expression, involving caveolin 1 dependent repression of extracellular regulated protein kinase activity. Part Fibre Toxicol 2019; 16:37. [PMID: 31619255 PMCID: PMC6796418 DOI: 10.1186/s12989-019-0324-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 09/27/2019] [Indexed: 01/13/2023] Open
Abstract
Background Gold nanoparticles (Au-NPs) have extensive applications in electronics and biomedicine, resulting in increased exposure and prompting safety concerns for human health. After absorption, nanoparticles enter circulation and effect endothelial cells. We previously showed that exposure to Au-NPs (40–50 nm) collapsed endothelial tight junctions and increased their paracellular permeability. Inhaled nanoparticles have gained significant attention due to their biodistribution in the brain; however, little is known regarding their role in cerebral edema. The present study investigated the expression of aquaporin 1 (AQP1) in the cerebral endothelial cell line, bEnd.3, stimulated by Au-NPs. Results We found that treatment with Au-NPs induced AQP1 expression and increased endothelial permeability to water. Au-NP exposure rapidly boosted the phosphorylation levels of focal adhesion kinase (FAK) and AKT, increased the accumulation of caveolin 1 (Cav1), and reduced the activity of extracellular regulated protein kinases (ERK). The inhibition of AKT (GDC-0068) or FAK (PF-573228) not only rescued ERK activity but also prevented AQP1 induction, whereas Au-NP-mediated Cav1 accumulation remained unaltered. Neither these signaling molecules nor AQP1 expression responded to Au-NPs while Cav1 was silenced. Inhibition of ERK activity (U0126) remarkably enhanced Cav1 and AQP1 expression in bEnd.3 cells. These data demonstrate that Au-NP-mediated AQP1 induction is Cav1 dependent, but requires the repression on ERK activity. Mice receiving intranasally administered Au-NPs displayed cerebral edema, significantly augmented AQP1 protein levels; furthermore, mild focal lesions were observed in the cerebral parenchyma. Conclusions These data suggest that the subacute exposure of nanoparticles might induce cerebral edema, involving the Cav1 dependent accumulation on endothelial AQP1.
Collapse
Affiliation(s)
- Ching-Yi Chen
- Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, 250 Wuxing Street, Taipei, 110, Taiwan.,Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.,School of Pharmacy, Taipei Medical University, Taipei, Taiwan
| | - Po-Lin Liao
- School of Pharmacy, Taipei Medical University, Taipei, Taiwan.,Institute of Food Safety and Health Risk Assessment, School of Pharmaceutical Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Chi-Hao Tsai
- Institute of Food Safety and Health Risk Assessment, School of Pharmaceutical Sciences, National Yang-Ming University, Taipei, Taiwan
| | - Yen-Ju Chan
- Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, 250 Wuxing Street, Taipei, 110, Taiwan.,Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Yu-Wen Cheng
- School of Pharmacy, Taipei Medical University, Taipei, Taiwan
| | - Ling-Ling Hwang
- Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, 250 Wuxing Street, Taipei, 110, Taiwan.,Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan
| | - Kuan-Hung Lin
- Institute of Biomedical Sciences, Mackay Medical College, New Taipei city, Taiwan
| | - Ting-Ling Yen
- Department of Medical Research, Cathay General Hospital, Taipei, 22174, Taiwan
| | - Ching-Hao Li
- Department of Physiology, School of Medicine, College of Medicine, Taipei Medical University, 250 Wuxing Street, Taipei, 110, Taiwan. .,Graduate Institute of Medical Sciences, College of Medicine, Taipei Medical University, Taipei, Taiwan.
| |
Collapse
|
14
|
Aquaporin-4 facilitator TGN-073 promotes interstitial fluid circulation within the blood-brain barrier: [17O]H2O JJVCPE MRI study. Neuroreport 2019; 29:697-703. [PMID: 29481527 PMCID: PMC5965936 DOI: 10.1097/wnr.0000000000000990] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The blood–brain barrier (BBB), which imposes significant water permeability restriction, effectively isolates the brain from the systemic circulation. Seemingly paradoxical, the abundance of aquaporin-4 (AQP-4) on the inside of the BBB strongly indicates the presence of unique water dynamics essential for brain function. On the basis of the highly specific localization of AQP-4, namely, astrocyte end feet at the glia limitans externa and pericapillary Virchow–Robin space, we hypothesized that the AQP-4 system serves as an interstitial fluid circulator, moving interstitial fluid from the glia limitans externa to pericapillary Virchow–Robin space to ensure proper glymphatic flow draining into the cerebrospinal fluid. The hypothesis was tested directly using the AQP-4 facilitator TGN-073 developed in our laboratory, and [17O]H2O JJ vicinal coupling proton exchange MRI, a method capable of tracing water molecules delivered into the blood circulation. The results unambiguously showed that facilitation of AQP-4 by TGN-073 increased turnover of interstitial fluid through the system, resulting in a significant reduction in [17O]H2O contents of cortex with normal flux into the cerebrospinal fluid. The study further suggested that in addition to providing the necessary water for proper glymphatic flow, the AQP-4 system produces a water gradient within the interstitial space promoting circulation of interstitial fluid within the BBB.
Collapse
|
15
|
Abbott NJ, Pizzo ME, Preston JE, Janigro D, Thorne RG. The role of brain barriers in fluid movement in the CNS: is there a 'glymphatic' system? Acta Neuropathol 2018; 135:387-407. [PMID: 29428972 DOI: 10.1007/s00401-018-1812-4] [Citation(s) in RCA: 335] [Impact Index Per Article: 55.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 01/16/2018] [Accepted: 01/24/2018] [Indexed: 12/15/2022]
Abstract
Brain fluids are rigidly regulated to provide stable environments for neuronal function, e.g., low K+, Ca2+, and protein to optimise signalling and minimise neurotoxicity. At the same time, neuronal and astroglial waste must be promptly removed. The interstitial fluid (ISF) of the brain tissue and the cerebrospinal fluid (CSF) bathing the CNS are integral to this homeostasis and the idea of a glia-lymph or 'glymphatic' system for waste clearance from brain has developed over the last 5 years. This links bulk (convective) flow of CSF into brain along the outside of penetrating arteries, glia-mediated convective transport of fluid and solutes through the brain extracellular space (ECS) involving the aquaporin-4 (AQP4) water channel, and finally delivery of fluid to venules for clearance along peri-venous spaces. However, recent evidence favours important amendments to the 'glymphatic' hypothesis, particularly concerning the role of glia and transfer of solutes within the ECS. This review discusses studies which question the role of AQP4 in ISF flow and the lack of evidence for its ability to transport solutes; summarizes attributes of brain ECS that strongly favour the diffusion of small and large molecules without ISF flow; discusses work on hydraulic conductivity and the nature of the extracellular matrix which may impede fluid movement; and reconsiders the roles of the perivascular space (PVS) in CSF-ISF exchange and drainage. We also consider the extent to which CSF-ISF exchange is possible and desirable, the impact of neuropathology on fluid drainage, and why using CSF as a proxy measure of brain components or drug delivery is problematic. We propose that new work and key historical studies both support the concept of a perivascular fluid system, whereby CSF enters the brain via PVS convective flow or dispersion along larger caliber arteries/arterioles, diffusion predominantly regulates CSF/ISF exchange at the level of the neurovascular unit associated with CNS microvessels, and, finally, a mixture of CSF/ISF/waste products is normally cleared along the PVS of venules/veins as well as other pathways; such a system may or may not constitute a true 'circulation', but, at the least, suggests a comprehensive re-evaluation of the previously proposed 'glymphatic' concepts in favour of a new system better taking into account basic cerebrovascular physiology and fluid transport considerations.
Collapse
Affiliation(s)
- N Joan Abbott
- Faculty of Life Sciences and Medicine, Institute of Pharmaceutical Science, King's College London, Franklin Wilkins Building 3.82, 150 Stamford St, London, SE1 9NH, UK.
| | - Michelle E Pizzo
- Division of Pharmaceutical Sciences, University of Wisconsin-Madison School of Pharmacy, Madison, WI, USA
- Clinical Neuroengineering Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Jane E Preston
- Faculty of Life Sciences and Medicine, Institute of Pharmaceutical Science, King's College London, Franklin Wilkins Building 3.82, 150 Stamford St, London, SE1 9NH, UK
| | - Damir Janigro
- Flocel Inc., Cleveland, OH, USA
- Department of Physiology, Case Western Reserve University, Cleveland, OH, USA
| | - Robert G Thorne
- Division of Pharmaceutical Sciences, University of Wisconsin-Madison School of Pharmacy, Madison, WI, USA.
- Clinical Neuroengineering Training Program, University of Wisconsin-Madison, Madison, WI, USA.
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, USA.
- Cellular and Molecular Pathology Graduate Training Program, University of Wisconsin-Madison, Madison, WI, USA.
- Institute for Clinical and Translational Research, University of Wisconsin-Madison, Madison, WI, USA.
- , 5113 Rennebohm Hall, 777 Highland Avenue, Madison, WI, 53705, USA.
| |
Collapse
|
16
|
Hirt L, Price M, Benakis C, Badaut J. Aquaporins in neurological disorders. CLINICAL AND TRANSLATIONAL NEUROSCIENCE 2018. [DOI: 10.1177/2514183x17752902] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Affiliation(s)
- Lorenz Hirt
- Neurology service, department of clinical neurosciences, CHUV, Lausanne, Switzerland
- Centre de recherche en neurosciences (CRN), CHUV, Lausanne, Switzerland
| | - Melanie Price
- Neurology service, department of clinical neurosciences, CHUV, Lausanne, Switzerland
- Centre de recherche en neurosciences (CRN), CHUV, Lausanne, Switzerland
| | - Corinne Benakis
- Institute for Stroke and Dementia Research (ISD), Munich, Germany
| | - Jérôme Badaut
- CNRS UMR 5287, INCIA, University of Bordeaux, Bordeaux, France
- Department of Basic science, Loma Linda University, Loma Linda, CA, USA
| |
Collapse
|
17
|
Ishida Y, Kuninaka Y, Furukawa F, Kimura A, Nosaka M, Fukami M, Yamamoto H, Kato T, Shimada E, Hata S, Takayasu T, Eisenmenger W, Kondo T. Immunohistochemical analysis on aquaporin-1 and aquaporin-3 in skin wounds from the aspects of wound age determination. Int J Legal Med 2017; 132:237-242. [PMID: 29080917 DOI: 10.1007/s00414-017-1725-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Accepted: 10/20/2017] [Indexed: 12/24/2022]
Abstract
Immunohistochemical investigation of aquaporin (AQP)1 and AQP3 was performed in human skin wounds obtained from forensic autopsy cases. A total of 55 human skin wounds of different postinfliction intervals were collected as follows: group I, 0-3 days (n = 16); II, 4-7 days (n = 11); III, 9-14 days (n = 16); and IV, 17-21 days (n = 12). In uninjured skin samples, AQP1 and AQP3 could be slightly detected in dermal vessels and keratinocytes, respectively. The percentage of AQP1+ vessels and the number of AQP3+ keratinocytes were apparently elevated in accordance with wound ages. The number of AQP3+ keratinocytes was distinctly evident in groups II and III. Morphometrically, both AQP1+ vessel area and AQP3+ cell number were markedly increased in group II, compared with other three groups. With regard to forensic safety, AQP1+ vessel area of over 5% would imply wound ages of 4-12 days. Moreover, the positive area of > 15% would suggest wound age of 7-10 days. Especially, most samples of skin wounds aged 5-10 days except for only one sample (a 10-day-old wound) showed AQP3+ cell number of > 300, and the remaining other samples had that of < 300. Thus, the AQP3+ cell number of > 300 would indicate wound ages of 5-10 days. Collectively, immunohistochemical analyses of AQP1 and AQP3 in human skin wounds would support the objective accuracy of wound age determination.
Collapse
Affiliation(s)
- Yuko Ishida
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Yumi Kuninaka
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Fukumi Furukawa
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Akihiko Kimura
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Mizuho Nosaka
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Mie Fukami
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Hiroki Yamamoto
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Takashi Kato
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Emi Shimada
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Satoshi Hata
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan
| | - Tatsunori Takayasu
- Forensic Toxicology Unit, Department of Forensic Medicine and Pathology, Graduate School of Medical Science, Kanazawa University, 13-1 Takara-machi, Kanazawa, 920-8640, Japan
| | - Wolfgang Eisenmenger
- Institute of Legal Medicine, University of Munich, Nuβbaumstraβe 26, 80336, Munich, Germany
| | - Toshikazu Kondo
- Department of Forensic Medicine, Wakayama Medical University, 811-1 Kimiidera, Wakayama, 641-8509, Japan.
| |
Collapse
|
18
|
Nakada T, Kwee IL, Igarashi H, Suzuki Y. Aquaporin-4 Functionality and Virchow-Robin Space Water Dynamics: Physiological Model for Neurovascular Coupling and Glymphatic Flow. Int J Mol Sci 2017; 18:E1798. [PMID: 28820467 PMCID: PMC5578185 DOI: 10.3390/ijms18081798] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Revised: 08/15/2017] [Accepted: 08/16/2017] [Indexed: 11/16/2022] Open
Abstract
The unique properties of brain capillary endothelium, critical in maintaining the blood-brain barrier (BBB) and restricting water permeability across the BBB, have important consequences on fluid hydrodynamics inside the BBB hereto inadequately recognized. Recent studies indicate that the mechanisms underlying brain water dynamics are distinct from systemic tissue water dynamics. Hydrostatic pressure created by the systolic force of the heart, essential for interstitial circulation and lymphatic flow in systemic circulation, is effectively impeded from propagating into the interstitial fluid inside the BBB by the tightly sealed endothelium of brain capillaries. Instead, fluid dynamics inside the BBB is realized by aquaporin-4 (AQP-4), the water channel that connects astrocyte cytoplasm and extracellular (interstitial) fluid. Brain interstitial fluid dynamics, and therefore AQP-4, are now recognized as essential for two unique functions, namely, neurovascular coupling and glymphatic flow, the brain equivalent of systemic lymphatics.
Collapse
Affiliation(s)
- Tsutomu Nakada
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata 951-8585, Japan.
- Department of Neurology, University of California, Davis, VANCHCS, Martinez, CA 94553, USA.
| | - Ingrid L Kwee
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata 951-8585, Japan.
- Department of Neurology, University of California, Davis, VANCHCS, Martinez, CA 94553, USA.
| | - Hironaka Igarashi
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata 951-8585, Japan.
| | - Yuji Suzuki
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata 951-8585, Japan.
| |
Collapse
|
19
|
Qaiser MZ, Dolman DEM, Begley DJ, Abbott NJ, Cazacu-Davidescu M, Corol DI, Fry JP. Uptake and metabolism of sulphated steroids by the blood-brain barrier in the adult male rat. J Neurochem 2017; 142:672-685. [PMID: 28665486 PMCID: PMC5601180 DOI: 10.1111/jnc.14117] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Revised: 06/21/2017] [Accepted: 06/26/2017] [Indexed: 01/08/2023]
Abstract
Little is known about the origin of the neuroactive steroids dehydroepiandrosterone sulphate (DHEAS) and pregnenolone sulphate (PregS) in the brain or of their subsequent metabolism. Using rat brain perfusion in situ, we have found 3H‐PregS to enter more rapidly than 3H‐DHEAS and both to undergo extensive (> 50%) desulphation within 0.5 min of uptake. Enzyme activity for the steroid sulphatase catalysing this deconjugation was enriched in the capillary fraction of the blood–brain barrier and its mRNA expressed in cultures of rat brain endothelial cells and astrocytes. Although permeability measurements suggested a net efflux, addition of the efflux inhibitors GF120918 and/or MK571 to the perfusate reduced rather than enhanced the uptake of 3H‐DHEAS and 3H‐PregS; a further reduction was seen upon the addition of unlabelled steroid sulphate, suggesting a saturable uptake transporter. Analysis of brain fractions after 0.5 min perfusion with the 3H‐steroid sulphates showed no further metabolism of PregS beyond the liberation of free steroid pregnenolone. By contrast, DHEAS underwent 17‐hydroxylation to form androstenediol in both the steroid sulphate and the free steroid fractions, with some additional formation of androstenedione in the latter. Our results indicate a gain of free steroid from circulating steroid sulphates as hormone precursors at the blood–brain barrier, with implications for ageing, neurogenesis, neuronal survival, learning and memory. ![]()
Collapse
Affiliation(s)
- M Zeeshan Qaiser
- Blood-Brain Barrier Research Group, Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College London, London, UK
| | - Diana E M Dolman
- Blood-Brain Barrier Research Group, Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College London, London, UK
| | - David J Begley
- Blood-Brain Barrier Research Group, Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College London, London, UK
| | - N Joan Abbott
- Blood-Brain Barrier Research Group, Institute of Pharmaceutical Science, Faculty of Life Sciences & Medicine, King's College London, London, UK
| | - Mihaela Cazacu-Davidescu
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, UK
| | - Delia I Corol
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, UK
| | - Jonathan P Fry
- Department of Neuroscience, Physiology and Pharmacology, University College London, Gower Street, London, UK
| |
Collapse
|
20
|
Theodorakis PE, Müller EA, Craster RV, Matar OK. Physical insights into the blood-brain barrier translocation mechanisms. Phys Biol 2017; 14:041001. [PMID: 28586313 DOI: 10.1088/1478-3975/aa708a] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The number of individuals suffering from diseases of the central nervous system (CNS) is growing with an aging population. While candidate drugs for many of these diseases are available, most of these pharmaceutical agents cannot reach the brain rendering most of the drug therapies that target the CNS inefficient. The reason is the blood-brain barrier (BBB), a complex and dynamic interface that controls the influx and efflux of substances through a number of different translocation mechanisms. Here, we present these mechanisms providing, also, the necessary background related to the morphology and various characteristics of the BBB. Moreover, we discuss various numerical and simulation approaches used to study the BBB, and possible future directions based on multi-scale methods. We anticipate that this review will motivate multi-disciplinary research on the BBB aiming at the design of effective drug therapies.
Collapse
|
21
|
Role of choroid plexus in cerebrospinal fluid hydrodynamics. Neuroscience 2017; 354:69-87. [DOI: 10.1016/j.neuroscience.2017.04.025] [Citation(s) in RCA: 75] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 04/19/2017] [Accepted: 04/19/2017] [Indexed: 12/24/2022]
|
22
|
Rodriguez-Grande B, Konsman JP. Gas Diffusion in the CNS. J Neurosci Res 2017; 96:207-218. [PMID: 28504343 DOI: 10.1002/jnr.24077] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 03/23/2017] [Accepted: 04/10/2017] [Indexed: 12/21/2022]
Abstract
Gases have been long known to have essential physiological functions in the CNS such as respiration or regulation of vascular tone. Since gases have been classically considered to freely diffuse, research in gas biology has so far focused on mechanisms of gas synthesis and gas reactivity, rather than gas diffusion and transport. However, the discovery of gas pores during the last two decades and the characterization of diverse diffusion patterns through different membranes has raised the possibility that modulation of gas diffusion is also a physiologically relevant parameter. Here we review the means of gas movement into and within the brain through "free" diffusion and gas pores, notably aquaporins, discussing the role that gas diffusion may play in the modulation of gas function. We highlight how diffusion is relevant to neuronal signaling, volume transmission, and cerebrovascular control in the case of NO, one of the most extensively studied gases. We point out how facilitated transport can be especially relevant for gases with low permeability in lipid membranes like NH3 and discuss the possible implications of NH3 -permeable channels in physiology and hyperammonemic encephalopathy. We identify novel research questions about how modulation of gas diffusion could intervene in CNS pathologies. This emerging area of research can provide novel and interesting insights in the field of gas biology.
Collapse
|
23
|
Hladky SB, Barrand MA. Fluid and ion transfer across the blood-brain and blood-cerebrospinal fluid barriers; a comparative account of mechanisms and roles. Fluids Barriers CNS 2016; 13:19. [PMID: 27799072 PMCID: PMC5508927 DOI: 10.1186/s12987-016-0040-3] [Citation(s) in RCA: 156] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2016] [Accepted: 09/01/2016] [Indexed: 12/24/2022] Open
Abstract
The two major interfaces separating brain and blood have different primary roles. The choroid plexuses secrete cerebrospinal fluid into the ventricles, accounting for most net fluid entry to the brain. Aquaporin, AQP1, allows water transfer across the apical surface of the choroid epithelium; another protein, perhaps GLUT1, is important on the basolateral surface. Fluid secretion is driven by apical Na+-pumps. K+ secretion occurs via net paracellular influx through relatively leaky tight junctions partially offset by transcellular efflux. The blood-brain barrier lining brain microvasculature, allows passage of O2, CO2, and glucose as required for brain cell metabolism. Because of high resistance tight junctions between microvascular endothelial cells transport of most polar solutes is greatly restricted. Because solute permeability is low, hydrostatic pressure differences cannot account for net fluid movement; however, water permeability is sufficient for fluid secretion with water following net solute transport. The endothelial cells have ion transporters that, if appropriately arranged, could support fluid secretion. Evidence favours a rate smaller than, but not much smaller than, that of the choroid plexuses. At the blood-brain barrier Na+ tracer influx into the brain substantially exceeds any possible net flux. The tracer flux may occur primarily by a paracellular route. The blood-brain barrier is the most important interface for maintaining interstitial fluid (ISF) K+ concentration within tight limits. This is most likely because Na+-pumps vary the rate at which K+ is transported out of ISF in response to small changes in K+ concentration. There is also evidence for functional regulation of K+ transporters with chronic changes in plasma concentration. The blood-brain barrier is also important in regulating HCO3- and pH in ISF: the principles of this regulation are reviewed. Whether the rate of blood-brain barrier HCO3- transport is slow or fast is discussed critically: a slow transport rate comparable to those of other ions is favoured. In metabolic acidosis and alkalosis variations in HCO3- concentration and pH are much smaller in ISF than in plasma whereas in respiratory acidosis variations in pHISF and pHplasma are similar. The key similarities and differences of the two interfaces are summarized.
Collapse
Affiliation(s)
- Stephen B. Hladky
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD UK
| | - Margery A. Barrand
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD UK
| |
Collapse
|
24
|
Yang X, Ransom BR, Ma JF. The role of AQP4 in neuromyelitis optica: More answers, more questions. J Neuroimmunol 2016; 298:63-70. [DOI: 10.1016/j.jneuroim.2016.06.002] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 05/30/2016] [Accepted: 06/06/2016] [Indexed: 12/14/2022]
|
25
|
Stokum JA, Gerzanich V, Simard JM. Molecular pathophysiology of cerebral edema. J Cereb Blood Flow Metab 2016; 36:513-38. [PMID: 26661240 PMCID: PMC4776312 DOI: 10.1177/0271678x15617172] [Citation(s) in RCA: 352] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 10/21/2015] [Accepted: 10/22/2015] [Indexed: 12/25/2022]
Abstract
Advancements in molecular biology have led to a greater understanding of the individual proteins responsible for generating cerebral edema. In large part, the study of cerebral edema is the study of maladaptive ion transport. Following acute CNS injury, cells of the neurovascular unit, particularly brain endothelial cells and astrocytes, undergo a program of pre- and post-transcriptional changes in the activity of ion channels and transporters. These changes can result in maladaptive ion transport and the generation of abnormal osmotic forces that, ultimately, manifest as cerebral edema. This review discusses past models and current knowledge regarding the molecular and cellular pathophysiology of cerebral edema.
Collapse
Affiliation(s)
- Jesse A Stokum
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, USA
| | - Volodymyr Gerzanich
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, USA
| | - J Marc Simard
- Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, USA Department of Pathology, University of Maryland School of Medicine, Baltimore, USA Department of Physiology, University of Maryland School of Medicine, Baltimore, USA
| |
Collapse
|
26
|
Aquaporins: Their role in gastrointestinal malignancies. Cancer Lett 2016; 373:12-18. [PMID: 26780474 DOI: 10.1016/j.canlet.2016.01.003] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 12/28/2015] [Accepted: 01/06/2016] [Indexed: 12/15/2022]
Abstract
Aquaporins (AQPs) are small (~30 kDa monomers) integral membrane water transport proteins that allow water to flow through cell membranes in reaction to osmotic gradients in cells. In mammals, the family of AQPs has thirteen (AQP0-12) unique members that mediate critical biological functions. Since AQPs can impact cell proliferation, migration and angiogenesis, their role in various human cancers is well established. Recently, AQPs have been explored as potential diagnostic and therapeutic targets in gastrointestinal (GI) cancers. GI cancers encompass multiple sites including the colon, esophagus, stomach and pancreas. Research in the last three decades has revealed biological aspects and signaling pathways critical for the development of GI cancers. Since the majority of these cancers are very aggressive and rapidly metastasizes, identifying effective targets is crucial for treatment. Preclinical studies have utilized inhibitors of specific AQPs and knock down of AQP expression using siRNA. Although several studies have explored the role of AQPs in colorectal, esophageal, gastric, hepatocellular and pancreatic cancers, there is no comprehensive review compiling the available information on GI cancers as has been published for other malignancies such as ovarian cancer. Due to the similarities and association of various sites of GI cancers, it is helpful to consider these results collectively in order to better understand the role of specific AQPs in critical GI cancers. This review summarizes the current knowledge of the role of AQPs in GI malignancies with particular focus on diagnosis and therapeutic applications.
Collapse
|
27
|
Pandey PK, Sharma AK, Gupta U. Blood brain barrier: An overview on strategies in drug delivery, realistic in vitro modeling and in vivo live tracking. Tissue Barriers 2016; 4:e1129476. [PMID: 27141418 PMCID: PMC4836458 DOI: 10.1080/21688370.2015.1129476] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 12/01/2015] [Accepted: 12/04/2015] [Indexed: 12/25/2022] Open
Abstract
Blood brain barrier (BBB) is a group of astrocytes, neurons and endothelial cells, which makes restricted passage of various biological or chemical entities to the brain tissue. It gives protection to brain at one hand, but at the other hand it has very selective permeability for bio-actives and other foreign materials and is one of the major challenges for the drug delivery. Nanocarriers are promising to cross BBB utilizing alternative route of administration such as intranasal and intra-carotid drug delivery which bypasses BBB. In future more optimized drug delivery system can be achieved by compiling the best routes with the best carriers. Single photon emission tomography (SPECT) and different brain-on-a-chip in vitro models are being very reliable to study live in vivo tracking of BBB and its pathophysiology, respectively. In the current review we have tried to exploit mechanistically all these to understand and manage the various BBB disruptions in diseased condition along with crossing the hurdles occurring in drug or gene delivery across BBB.
Collapse
Affiliation(s)
- Pawan Kumar Pandey
- Department of Pharmacy; School of Chemical Sciences and Pharmacy, Central University of Rajasthan; Ajmer; Rajasthan, India
| | - Ashok Kumar Sharma
- Department of Pharmacy; School of Chemical Sciences and Pharmacy, Central University of Rajasthan; Ajmer; Rajasthan, India
| | - Umesh Gupta
- Department of Pharmacy; School of Chemical Sciences and Pharmacy, Central University of Rajasthan; Ajmer; Rajasthan, India
| |
Collapse
|
28
|
Nakada T. The Molecular Mechanisms of Neural Flow Coupling: A New Concept. J Neuroimaging 2015; 25:861-5. [PMID: 25704766 PMCID: PMC5023998 DOI: 10.1111/jon.12219] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 12/10/2014] [Indexed: 11/29/2022] Open
Abstract
The phenomenon known as neural flow coupling (NFC) occurs at the capillary level where there are no known pressure controlling structures. Recent developments in advanced magnetic resonance imaging technologies have made possible in vivo direct investigations of water physiology that have shed new insight on the water dynamics of the cortical pericapillary space and their complex functionality in relation to NFC. Neural activities initiate a chain of events that ultimately affect NFC. First, neural activities generate extracellular acidification. Extracellular acidosis in turn produces inhibition of aquaporin-4 (AQP-4) located at the end feet of pericapillary astrocytes, the water channel which regulates water influx into the pericapillary space and, hence, interstitial flow. Reduction of pericapillary water pressure results in a negative balance between pericapillary and intraluminal capillary pressure, allowing for capillary caliber expansion. Proton permeability through the tight junctions of the blood brain barrier is significantly high owing to the Grotthuss proton "tunneling" mechanism and, therefore, carbonic anhydrase (CA) type IV (CA-IV) anchored to the luminal surface of brain capillaries functions as scavenger of extracellular protons. CA-IV inhibition by acetazolamide or carbon dioxide results in the accumulation of extracellular protons, causing AQP-4 inhibition and a secondary increase in rCBF.
Collapse
Affiliation(s)
- Tsutomu Nakada
- Center for Integrated Human Brain Science, Brain Research InstituteUniversity of NiigataNiigataJapan
| |
Collapse
|
29
|
Suzuki Y, Nakamura Y, Yamada K, Igarashi H, Kasuga K, Yokoyama Y, Ikeuchi T, Nishizawa M, Kwee IL, Nakada T. Reduced CSF Water Influx in Alzheimer's Disease Supporting the β-Amyloid Clearance Hypothesis. PLoS One 2015; 10:e0123708. [PMID: 25946191 PMCID: PMC4422624 DOI: 10.1371/journal.pone.0123708] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2014] [Accepted: 03/05/2015] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVE To investigate whether water influx into cerebrospinal fluid (CSF) space is reduced in Alzheimer's patients as previously shown in the transgenic mouse model for Alzheimer's disease. METHODS Ten normal young volunteers (young control, 21-30 years old), ten normal senior volunteers (senior control, 60-78 years old, MMSE ≥ 29), and ten Alzheimer's disease (AD) patients (study group, 59-84 years old, MMSE: 13-19) participated in this study. All AD patients were diagnosed by neurologists specializing in dementia based on DSM-IV criteria. CSF dynamics were analyzed using positron emission tomography (PET) following an intravenous injection of 1,000 MBq [15O]H2O synthesized on-line. RESULTS Water influx into CSF space in AD patients, expressed as influx ratio, (0.755 ± 0.089) was significantly reduced compared to young controls (1.357 ± 0.185; p < 0.001) and also compared to normal senior controls (0.981 ± 0.253, p < 0.05). Influx ratio in normal senior controls was significantly reduced compared to young controls (p < 0.01). CONCLUSION Water influx into the CSF is significantly reduced in AD patients. β-amyloid clearance has been shown to be dependent on interstitial flow and CSF production. The current study indicates that reduction in water influx into the CSF may disturb the clearance rate of β-amyloid, and therefore be linked to the pathogenesis of AD. TRIAL REGISTRATION UMIN Clinical Trials Registry UMIN000011939.
Collapse
Affiliation(s)
- Yuji Suzuki
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Yukihiro Nakamura
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Kenichi Yamada
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Hironaka Igarashi
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Kensaku Kasuga
- Department of Molecular Genetics, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Yuichi Yokoyama
- Department of Psychiatry, Faculty of Medicine, University of Niigata, Niigata, Japan
| | - Takeshi Ikeuchi
- Department of Molecular Genetics, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Masatoyo Nishizawa
- Department of Neurology, Brain Research Institute, University of Niigata, Niigata, Japan
| | - Ingrid L. Kwee
- Department of Neurology, University of California Davis, Davis, California, United States of America
| | - Tsutomu Nakada
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Niigata, Japan
- Department of Neurology, University of California Davis, Davis, California, United States of America
- * E-mail:
| |
Collapse
|
30
|
Nguyen T, Toussaint J, Xue Y, Raval C, Cancel L, Russell S, Shou Y, Sedes O, Sun Y, Yakobov R, Tarbell JM, Jan KM, Rumschitzki DS. Aquaporin-1 facilitates pressure-driven water flow across the aortic endothelium. Am J Physiol Heart Circ Physiol 2015; 308:H1051-64. [PMID: 25659484 PMCID: PMC4551120 DOI: 10.1152/ajpheart.00499.2014] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 01/23/2015] [Indexed: 01/23/2023]
Abstract
Aquaporin-1, a ubiquitous water channel membrane protein, is a major contributor to cell membrane osmotic water permeability. Arteries are the physiological system where hydrostatic dominates osmotic pressure differences. In the present study, we show that the walls of large conduit arteries constitute the first example where hydrostatic pressure drives aquaporin-1-mediated transcellular/transendothelial flow. We studied cultured aortic endothelial cell monolayers and excised whole aortas of male Sprague-Dawley rats with intact and inhibited aquaporin-1 activity and with normal and knocked down aquaporin-1 expression. We subjected these systems to transmural hydrostatic pressure differences at zero osmotic pressure differences. Impaired aquaporin-1 endothelia consistently showed reduced engineering flow metrics (transendothelial water flux and hydraulic conductivity). In vitro experiments with tracers that only cross the endothelium paracellularly showed that changes in junctional transport cannot explain these reductions. Percent reductions in whole aortic wall hydraulic conductivity with either chemical blocking or knockdown of aquaporin-1 differed at low and high transmural pressures. This observation highlights how aquaporin-1 expression likely directly influences aortic wall mechanics by changing the critical transmural pressure at which its sparse subendothelial intima compresses. Such compression increases transwall flow resistance. Our endothelial and historic erythrocyte membrane aquaporin density estimates were consistent. In conclusion, aquaporin-1 significantly contributes to hydrostatic pressure-driven water transport across aortic endothelial monolayers, both in culture and in whole rat aortas. This transport, and parallel junctional flow, can dilute solutes that entered the wall paracellularly or through endothelial monolayer disruptions. Lower atherogenic precursor solute concentrations may slow their intimal entrainment kinetics.
Collapse
Affiliation(s)
- Tieuvi Nguyen
- Department of Biomedical Engineering, City College of the City University of New York, New York, New York
| | - Jimmy Toussaint
- Department of Chemical Engineering, City College of the City University of New York, New York, New York
| | - Yan Xue
- Department of Chemical Engineering, City College of the City University of New York, New York, New York; Biology Department, City College and GSUC of The City College of New York, New York, New York; and
| | - Chirag Raval
- Department of Biomedical Engineering, City College of the City University of New York, New York, New York
| | - Limary Cancel
- Department of Biomedical Engineering, City College of the City University of New York, New York, New York
| | - Stewart Russell
- Department of Biomedical Engineering, City College of the City University of New York, New York, New York
| | - Yixin Shou
- Department of Chemical Engineering, City College of the City University of New York, New York, New York
| | - Omer Sedes
- Department of Chemical Engineering, City College of the City University of New York, New York, New York
| | - Yu Sun
- Department of Chemical Engineering, City College of the City University of New York, New York, New York
| | - Roman Yakobov
- Department of Chemical Engineering, City College of the City University of New York, New York, New York
| | - John M Tarbell
- Department of Biomedical Engineering, City College of the City University of New York, New York, New York
| | - Kung-ming Jan
- Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, New York
| | - David S Rumschitzki
- Department of Chemical Engineering, City College of the City University of New York, New York, New York; Biology Department, City College and GSUC of The City College of New York, New York, New York; and Department of Medicine, College of Physicians and Surgeons of Columbia University, New York, New York
| |
Collapse
|
31
|
Saadoun S, Papadopoulos MC. Role of membrane complement regulators in neuromyelitis optica. Mult Scler 2015; 21:1644-54. [PMID: 25698168 DOI: 10.1177/1352458515571446] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2014] [Accepted: 01/13/2015] [Indexed: 11/16/2022]
Abstract
BACKGROUND It is unclear why AQP4-IgG primarily causes central nervous system lesions by activating complement, but generally spares peripheral AQP4-expressing organs. OBJECTIVES To determine whether peripheral AQP4-expressing cells are protected from complement-mediated damage by expressing complement regulators. METHODS Human tissue and cultured human cells were immunostained for aquaporin-4 (AQP4), CD46, CD55 and CD59. We also determined the vulnerability to AQP4-IgG and complement-mediated damage of astrocytes cultured alone or co-cultured with endothelial cells. RESULTS In normal brain, astrocyte end-feet express AQP4, but are devoid of CD46, CD55 and CD59. Immunoreactivity for CD46, CD55 and CD59 is not increased in or around neuromyelitis optica lesions. In kidney AQP4 is co-expressed with CD46 and CD55, in stomach AQP4 is co-expressed with CD46 and in skeletal muscle AQP4 is co-expressed with CD46. Astrocytes cultured alone co-express AQP4 and CD59 but, in astrocyte-endothelial co-cultures, AQP4 is found in cell processes devoid of CD59. Astrocytes co-cultured with endothelial cells are more vulnerable to AQP4-IgG and complement-mediated lysis than astrocytes cultured alone. CONCLUSIONS Complement regulators protect peripheral organs, but not the central nervous system, from AQP4-IgG and complement-mediated damage. Our findings may explain why neuromyelitis optica primarily damages the central nervous system, but spares peripheral organs.
Collapse
|
32
|
Campos-Bedolla P, Walter FR, Veszelka S, Deli MA. Role of the Blood–Brain Barrier in the Nutrition of the Central Nervous System. Arch Med Res 2014; 45:610-38. [DOI: 10.1016/j.arcmed.2014.11.018] [Citation(s) in RCA: 114] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Accepted: 11/24/2014] [Indexed: 12/22/2022]
|
33
|
Nakada T. Virchow-Robin space and aquaporin-4: new insights on an old friend. Croat Med J 2014; 55:328-36. [PMID: 25165047 PMCID: PMC4157385 DOI: 10.3325/cmj.2014.55.328] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 07/09/2014] [Indexed: 11/18/2022] Open
Abstract
Recent studies have strongly indicated that the classic circulation model of cerebrospinal fluid (CSF) is no longer valid. The production of CSF is not only dependent on the choroid plexus but also on water flux in the peri-capillary (Virchow Robin) space. Historically, CSF flow through the Virchow Robin space is known as interstitial flow, the physiological significance of which is now fully understood. This article briefly reviews the modern concept of CSF physiology and the Virchow-Robin space, in particular its functionalities critical for central nervous system neural activities. Water influx into the Virchow Robin space and, hence, interstitial flow is regulated by aquaporin-4 (AQP-4) localized in the endfeet of astrocytes, connecting the intracellular cytosolic fluid space of astrocytes and the Virchow Robin space. Interstitial flow has a functionality equivalent to systemic lymphatics, on which clearance of β-amyloid is strongly dependent. Autoregulation of brain blood flow serves to maintain a constant inner capillary fluid pressure, allowing fluid pressure of the Virchow Robin space to regulate regional cerebral blood flow (rCBF) based on AQP-4 gating. Excess heat produced by neural activities is effectively removed from the area of activation by increased rCBF by closing AQP-4 channels. This neural flow coupling (NFC) is likely mediated by heat generated proton channels.
Collapse
Affiliation(s)
- Tsutomu Nakada
- Tsutomu Nakada, Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, 1-757 Asahimachi, Niigata, 951-8585, Japan,
| |
Collapse
|
34
|
Mohammadi MT, Dehghani GA. Nitric oxide as a regulatory factor for aquaporin-1 and 4 gene expression following brain ischemia/reperfusion injury in rat. Pathol Res Pract 2014; 211:43-9. [PMID: 25441658 DOI: 10.1016/j.prp.2014.07.014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2013] [Revised: 06/29/2014] [Accepted: 07/21/2014] [Indexed: 12/28/2022]
Abstract
Although the role of aquaporin-4 (AQP4) and aquaporin-1 (AQP1) channels in ischemia-induced brain edema has been previously reported, nitric oxide (NO) modulation of these channels has not been investigated. The aim of this study was to evaluate the NO modulation of AQPs gene expression after brain ischemia/reperfusion (I/R) in rats. The experiment was performed in three groups of rats: sham, control ischemic and L-NAME pretreated (1 mg/kg). Brain ischemia was induced by 60 min middle cerebral artery occlusion (MCAO) under continuous recording of regional cerebral blood flow (rCBF) followed by 12 h reperfusion. Brain edema was assessed by dry/wet method, and Quantitative RT-PCR was used for assessment of mRNA levels of AQPs. There was 80% reduction in rCBF during MCAO. Brain cerebral ischemia elevated the brain water content from 78.66±0.17% to 81.93±0.60%, and inhibition of NO production by L-NAME significantly reduced this elevation (79.74±0.79%). The mRNA expression of AQP1 increased, but AQP4 decreased in response to I/R. l-NAME pretreatment significantly decreased AQP1 mRNA and prevented the reduction of AQP4 mRNA. The findings of this study indicated that brain I/R injury provokes brain edema by alterations of AQPs expression, and the NO is the main signaling factor that modulates gene expression of these channels.
Collapse
Affiliation(s)
- Mohammad Taghi Mohammadi
- Department of Physiology and Biophysics, School of Medicine, Baqiyatallah University of Medical Sciences, Tehran, Iran.
| | - Golam Abbas Dehghani
- Department of Physiology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| |
Collapse
|
35
|
Igarashi H, Suzuki Y, Kwee IL, Nakada T. Water influx into cerebrospinal fluid is significantly reduced in senile plaque bearing transgenic mice, supporting beta-amyloid clearance hypothesis of Alzheimer's disease. Neurol Res 2014; 36:1094-8. [PMID: 25082552 PMCID: PMC4188033 DOI: 10.1179/1743132814y.0000000434] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Recent studies on cerebrospinal fluid (CSF) homeostasis emphasize the importance of water influx into the peri-capillary (Virchow-Robin) space through aquaporin 4 (AQP-4). This water flow is believed to have the functionality equivalent to the systemic lymphatic system and plays a critical role in beta-amyloid clearance. Using a newly developed molecular imaging technique capable of tracing water molecules, in vivo, water influx into the CSF was quantitatively analyzed in senile plaque (SP) bearing transgenic Alzheimer's disease (AD) model mice. The results unequivocally demonstrated that water influx into CSF is significantly impaired in SP-bearing transgenic mice, the degree of which being virtually identical to that previously observed in AQP-4 knockout mice. The study strongly indicates that disturbance in AQP-4-based water flow and, hence, impairment in beta-amyloid clearance play a significant role in SP formation.
Collapse
Affiliation(s)
- Hironaka Igarashi
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Chuo-ku, Niigata, Japan
| | - Yuji Suzuki
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Chuo-ku, Niigata, Japan
| | - Ingrid L Kwee
- Department of Neurology, University of California, Davis, Martinez, CA, USA
| | - Tsutomu Nakada
- Center for Integrated Human Brain Science, Brain Research Institute, University of Niigata, Chuo-ku, Niigata, Japan
- Department of Neurology, University of California, Davis, Martinez, CA, USA
| |
Collapse
|
36
|
Water influx into cerebrospinal fluid is primarily controlled by aquaporin-4, not by aquaporin-1: 17O JJVCPE MRI study in knockout mice. Neuroreport 2014; 25:39-43. [PMID: 24231830 PMCID: PMC4235386 DOI: 10.1097/wnr.0000000000000042] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Recent studies on cerebrospinal fluid (CSF) homeostasis emphasize the importance of water flux through the pericapillary (Virchow-Robin) space for both CSF production and reabsorption (Oreskovic and Klarica hypothesis), and challenge the classic CSF circulation theory, which proposes that CSF is primarily produced by the choroid plexus and reabsorbed by the arachnoid villi. Active suppression of aquaporin-1 (AQP-1) expression within brain capillaries and preservation of AQP-1 within the choroid plexus together with pericapillary water regulation by AQP-4 provide a unique opportunity for testing this recent hypothesis. We investigated water flux into three representative regions of the brain, namely, the cortex, basal ganglia, and third ventricle using a newly developed water molecular MRI technique based on JJ vicinal coupling between O and adjacent protons and water molecule proton exchanges (JJVCPE imaging) in AQP-1 and AQP-4 knockout mice in vivo. The results clearly indicate that water influx into the CSF is regulated by AQP-4, and not by AQP-1, strongly supporting the Oreskovic and Klarica hypothesis.
Collapse
|
37
|
Lorthois S, Duru P, Billanou I, Quintard M, Celsis P. Kinetic modeling in the context of cerebral blood flow quantification by H2(15)O positron emission tomography: the meaning of the permeability coefficient in Renkin-Crone׳s model revisited at capillary scale. J Theor Biol 2014; 353:157-69. [PMID: 24637002 DOI: 10.1016/j.jtbi.2014.03.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Revised: 02/21/2014] [Accepted: 03/04/2014] [Indexed: 10/25/2022]
Abstract
One the one hand, capillary permeability to water is a well-defined concept in microvascular physiology, and linearly relates the net convective or diffusive mass fluxes (by unit area) to the differences in pressure or concentration, respectively, that drive them through the vessel wall. On the other hand, the permeability coefficient is a central parameter introduced when modeling diffusible tracers transfer from blood vessels to tissue in the framework of compartmental models, in such a way that it is implicitly considered as being identical to the capillary permeability. Despite their simplifying assumptions, such models are at the basis of blood flow quantification by H2(15)O Positron Emission Tomgraphy. In the present paper, we use fluid dynamic modeling to compute the transfers of H2(15)O between the blood and brain parenchyma at capillary scale. The analysis of the so-obtained kinetic data by the Renkin-Crone model, the archetypal compartmental model, demonstrates that, in this framework, the permeability coefficient is highly dependent on both flow rate and capillary radius, contrarily to the central hypothesis of the model which states that it is a physiological constant. Thus, the permeability coefficient in Renkin-Crone׳s model is not conceptually identical to the physiologic permeability as implicitly stated in the model. If a permeability coefficient is nevertheless arbitrarily chosen in the computed range, the flow rate determined by the Renkin-Crone model can take highly inaccurate quantitative values. The reasons for this failure of compartmental approaches in the framework of brain blood flow quantification are discussed, highlighting the need for a novel approach enabling to fully exploit the wealth of information available from PET data.
Collapse
Affiliation(s)
- Sylvie Lorthois
- CNRS, IMFT (Institut de Mécanique des Fluides de Toulouse), Allée Camille Soula, F-31400 Toulouse, France; Université de Toulouse, INPT, UPS, IMFT (Institut de Mécanique des Fluides de Toulouse), Allée Camille Soula, F-31400 Toulouse, France.
| | - Paul Duru
- Université de Toulouse, INPT, UPS, IMFT (Institut de Mécanique des Fluides de Toulouse), Allée Camille Soula, F-31400 Toulouse, France; CNRS, IMFT (Institut de Mécanique des Fluides de Toulouse), Allée Camille Soula, F-31400 Toulouse, France
| | - Ian Billanou
- Université de Toulouse, INPT, UPS, IMFT (Institut de Mécanique des Fluides de Toulouse), Allée Camille Soula, F-31400 Toulouse, France; CNRS, IMFT (Institut de Mécanique des Fluides de Toulouse), Allée Camille Soula, F-31400 Toulouse, France
| | - Michel Quintard
- CNRS, IMFT (Institut de Mécanique des Fluides de Toulouse), Allée Camille Soula, F-31400 Toulouse, France; Université de Toulouse, INPT, UPS, IMFT (Institut de Mécanique des Fluides de Toulouse), Allée Camille Soula, F-31400 Toulouse, France
| | - Pierre Celsis
- INSERM, UMR 825, Cerebral Imaging and Neurological Handicaps, Toulouse F-31000, France; Université Toulouse III Paul Sabatier, UMR 825, Toulouse F-31000, France
| |
Collapse
|
38
|
Di Paolo A, Gori G, Tascini C, Danesi R, Del Tacca M. Clinical pharmacokinetics of antibacterials in cerebrospinal fluid. Clin Pharmacokinet 2014; 52:511-42. [PMID: 23605634 DOI: 10.1007/s40262-013-0062-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
In the past 20 years, an increased discrepancy between new available antibacterials and the emergence of multidrug-resistant strains has been observed. This condition concerns physicians involved in the treatment of central nervous system (CNS) infections, for which clinical and microbiological success depends on the rapid achievement of bactericidal concentrations. In order to accomplish this aim, the choice of drugs is based on their disposition toward the cerebrospinal fluid (CSF), which is influenced by the physicochemical characteristics of antibacterials. A reduced distribution into CSF has been documented for beta-lactams, especially cephalosporins and carbapenems, on the basis of their hydrophilic nature. However, they represent a cornerstone of the majority of combined therapeutic schemes for their ability to achieve bactericidal concentrations, especially in the presence of inflamed meninges. The good tolerability of beta-lactams makes possible high daily dose intensities, which may be associated with increased probability of cure. Furthermore, the adoption of continuous infusion seems to be a fruitful option. Fluoroquinolones, namely moxifloxacin, and antituberculosis drugs, together with the agents such as linezolid, reach the highest CSF/plasma concentration ratio, which is greater than 0.8, and for most of these drugs it is near 1. For all drugs that are currently used for the treatment of CNS infections, the evaluation of pharmacokinetic/pharmacodynamic parameters, on the basis of dosing regimens and their time-dependent or concentration-dependent pattern of bacterial killing, remains an important aspect of clinical investigation and medical practice.
Collapse
Affiliation(s)
- Antonello Di Paolo
- Division of Pharmacology, Department of Clinical and Experimental Medicine, University of Pisa, Via Roma 55, 56126, Pisa, Italy
| | | | | | | | | |
Collapse
|
39
|
Abstract
Aquaporins are a group of proteins with high-selective permeability for water. A subgroup called aquaglyceroporins is also permeable to glycerol, urea and a few other solutes. Aquaporin function has mainly been studied in the brain, kidney, glands and skeletal muscle, while the information about aquaporins in the heart is still scarce. The current review explores the recent advances in this field, bringing aquaporins into focus in the context of myocardial ischemia, reperfusion, and blood osmolarity disturbances. Since the amount of data on aquaporins in the heart is still limited, examples and comparisons from better-studied areas of aquaporin biology have been used. The human heart expresses aquaporin-1, -3, -4 and -7 at the protein level. The potential roles of aquaporins in the heart are discussed, and some general phenomena that the myocardial aquaporins share with aquaporins in other organs are elaborated. Cardiac aquaporin-1 is mostly distributed in the microvasculature. Its main role is transcellular water flux across the endothelial membranes. Aquaporin-4 is expressed in myocytes, both in cardiac and in skeletal muscle. In addition to water flux, its function is connected to the calcium signaling machinery. It may play a role in ischemia-reperfusion injury. Aquaglyceroporins, especially aquaporin-7, may serve as a novel pathway for nutrient delivery into the heart. They also mediate toxicity of various poisons. Aquaporins cannot influence permeability by gating, therefore, their function is regulated by changes of expression-on the levels of transcription, translation (by microRNAs), post-translational modification, membrane trafficking, ubiquitination and subsequent degradation. Studies using mice genetically deficient for aquaporins have shown rather modest changes in the heart. However, they might still prove to be attractive targets for therapy directed to reduce myocardial edema and injury caused by ischemia and reperfusion.
Collapse
|
40
|
Tzartos JS, Stergiou C, Kilidireas K, Zisimopoulou P, Thomaidis T, Tzartos SJ. Anti-aquaporin-1 autoantibodies in patients with neuromyelitis optica spectrum disorders. PLoS One 2013; 8:e74773. [PMID: 24086369 PMCID: PMC3781161 DOI: 10.1371/journal.pone.0074773] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2013] [Accepted: 08/07/2013] [Indexed: 12/02/2022] Open
Abstract
Autoantibodies against aquaporin-4 (AQP4), a water channel in CNS astrocytes, are detected in ∼50–80% of patients with neuromyelitis optica spectrum disorders (NMOsd), characterized by longitudinally extensive transverse myelitis (LETM) and/or optic neuritis. Although these autoantibodies present an invaluable biomarker for NMOsd and for the differential diagnosis of multiple sclerosis (MS), diagnosis of anti-AQP4-seronegative NMOsd remains challenging. We hypothesized that seronegative NMOsd patients might have autoantibodies against aquaporin-1 (AQP1), another water channel in CNS astrocytes. We initially developed a radioimmunoprecipitation assay to search for anti-AQP1 antibodies in sera from 632 individuals. Anti-AQP1 or anti-AQP4 autoantibodies were detected in 16.7% and 12%, respectively, of 348 patients with suspected NMOsd. Anti-AQP1 specificity was confirmed by competition, protein immunoblotting and ELISA assays, whereas epitope localization was studied by immunoadsorption on intact cells expressing AQP1 and peptide mapping experiments. Most anti-AQP1 autoantibodies were of the complement-activating IgG1 subclass and the majority bound to the extracellular domain of AQP1, suggesting a possible pathogenic role. Five out of 42 MS patients had anti-AQP1 antibodies, but 2 of them also had spinal cord lesions, while the anti-AQP1 antibodies in the other 3 bound to the cytoplasmic domain of AQP1. Anti-AQP1 antibodies were not detected in 100 healthy individuals or 142 patients with non-demyelinating neuroimmune diseases. Analysis of 17 anti-AQP1+/anti-AQP4- patients with suspected NMOsd showed that 5 had NMO and 11 had LETM. 12/17 of these sera bound predominantly to the extracellular AQP1 loop-Α. Overall, we found that anti-AQP1 autoantibodies are present in a subgroup of patients with chronic demyelination in the CNS and similarities with anti-AQP4-seronegative NMOsd, offering a novel potential biomarker for CNS demyelination disorders.
Collapse
Affiliation(s)
- John S. Tzartos
- Department of Biochemistry, Hellenic Pasteur Institute, Athens, Greece
- Department of Neurology, General Hospital “Red Cross", Athens, Greece
- * E-mail: (JST); (SJT)
| | - Christos Stergiou
- Department of Biochemistry, Hellenic Pasteur Institute, Athens, Greece
| | - Konstantinos Kilidireas
- Department of Neurology, Aeginition Hospital, School of Medicine, National and Kapodistrian University, Athens, Greece
| | | | - Thomas Thomaidis
- Department of Neurology, General Hospital “Red Cross", Athens, Greece
| | - Socrates J. Tzartos
- Department of Biochemistry, Hellenic Pasteur Institute, Athens, Greece
- Department of Pharmacy, University of Patras, Patras, Greece
- * E-mail: (JST); (SJT)
| |
Collapse
|
41
|
Abstract
The effects of the aquaporin-4 (AQP-4) inhibitor TGN-020 on regional cerebral blood flow (rCBF) was examined in wild-type (WT) and AQP-4 knockout (KO) mice in vivo. Although baseline absolute rCBF of WT and KO mice were equivalent (158.9 ± 17.7 and 155.5 ± 10.4 ml/100 g/min, respectively), TGN-020 produced a significant increase in rCBF compared with saline-treated WT mice (control), reaching a plateau 20 min after administration (118.45 ± 8.13%, P<0.01). TGN-020 showed no effect on KO mice, supporting the concept that the observed increase in rCBF in WT mice was AQP-4 dependent. Administration of acetazolamide (positive control) produced an even greater increase in rCBF in WT compared with TGN-020 and a similar response in KO mice as well, reaching a sustained plateau 5 min after administration (138.50 ± 9.75 and 138.52 ± 9.76%, respectively, P<0.01 compared with baseline or saline-treated control mice). The study demonstrated that AQP-4 plays a role in regulation of rCBF.
Collapse
|
42
|
Abstract
The aquaporins (AQPs) are plasma membrane water-transporting proteins. AQP4 is the principal member of this protein family in the CNS, where it is expressed in astrocytes and is involved in water movement, cell migration and neuroexcitation. AQP1 is expressed in the choroid plexus, where it facilitates cerebrospinal fluid secretion, and in dorsal root ganglion neurons, where it tunes pain perception. The AQPs are potential drug targets for several neurological conditions. Astrocytoma cells strongly express AQP4, which may facilitate their infiltration into the brain, and the neuroinflammatory disease neuromyelitis optica is caused by AQP4-specific autoantibodies that produce complement-mediated astrocytic damage.
Collapse
Affiliation(s)
- Marios C Papadopoulos
- Academic Neurosurgery Unit, St. George's, University of London, Tooting, London, SW17 0RE, UK. mpapadop@sgul. ac.uk
| | | |
Collapse
|
43
|
Altered aquaporins in the brains of mice submitted to intermittent hypoxia model of sleep apnea. Respir Physiol Neurobiol 2013; 185:217-21. [DOI: 10.1016/j.resp.2012.10.012] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 10/23/2012] [Accepted: 10/24/2012] [Indexed: 11/18/2022]
|
44
|
Brain water channel proteins in health and disease. Mol Aspects Med 2012; 33:562-78. [DOI: 10.1016/j.mam.2012.03.008] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2012] [Revised: 03/28/2012] [Accepted: 03/31/2012] [Indexed: 02/07/2023]
|
45
|
Endothelial cells and astrocytes: a concerto en duo in ischemic pathophysiology. Int J Cell Biol 2012; 2012:176287. [PMID: 22778741 PMCID: PMC3388591 DOI: 10.1155/2012/176287] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2012] [Accepted: 04/30/2012] [Indexed: 11/17/2022] Open
Abstract
The neurovascular/gliovascular unit has recently gained increased attention in cerebral ischemic research, especially regarding the cellular and molecular changes that occur in astrocytes and endothelial cells. In this paper we summarize the recent knowledge of these changes in association with edema formation, interactions with the basal lamina, and blood-brain barrier dysfunctions. We also review the involvement of astrocytes and endothelial cells with recombinant tissue plasminogen activator, which is the only FDA-approved thrombolytic drug after stroke. However, it has a narrow therapeutic time window and serious clinical side effects. Lastly, we provide alternative therapeutic targets for future ischemia drug developments such as peroxisome proliferator- activated receptors and inhibitors of the c-Jun N-terminal kinase pathway. Targeting the neurovascular unit to protect the blood-brain barrier instead of a classical neuron-centric approach in the development of neuroprotective drugs may result in improved clinical outcomes after stroke.
Collapse
|
46
|
Abbott NJ, Dolman DEM, Drndarski S, Fredriksson SM. An improved in vitro blood-brain barrier model: rat brain endothelial cells co-cultured with astrocytes. Methods Mol Biol 2012; 814:415-30. [PMID: 22144323 DOI: 10.1007/978-1-61779-452-0_28] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
In vitro blood-brain barrier (BBB) models using primary cultured brain endothelial cells are important for establishing cellular and molecular mechanisms of BBB function. Co-culturing with BBB-associated cells especially astrocytes to mimic more closely the in vivo condition leads to upregulation of the BBB phenotype in the brain endothelial cells. Rat brain endothelial cells (RBECs) are a valuable tool allowing ready comparison with in vivo studies in rodents; however, it has been difficult to obtain pure brain endothelial cells, and few models achieve a transendothelial electrical resistance (TEER, measure of tight junction efficacy) of >200 Ω cm(2), i.e. the models are still relatively leaky. Here, we describe methods for preparing high purity RBECs and neonatal rat astrocytes, and a co-culture method that generates a robust, stable BBB model that can achieve TEER >600 Ω cm(2). The method is based on >20 years experience with RBEC culture, together with recent improvements to kill contaminating cells and encourage BBB differentiation.Astrocytes are isolated by mechanical dissection and cell straining and are frozen for later co-culture. RBECs are isolated from 3-month-old rat cortices. The brains are cleaned of meninges and white matter and enzymatically and mechanically dissociated. Thereafter, the tissue homogenate is centrifuged in bovine serum albumin to separate vessel fragments from other cells that stick to the myelin plug. The vessel fragments undergo a second enzyme digestion to separate pericytes from vessels and break down vessels into shorter segments, after which a Percoll gradient is used to separate capillaries from venules, arterioles, and single cells. To kill remaining contaminating cells such as pericytes, the capillary fragments are plated in puromycin-containing medium and RBECs grown to 50-60% confluence. They are then passaged onto filters for co-culture with astrocytes grown in the bottom of the wells. The whole procedure takes ∼2 weeks, using pre-frozen astrocytes, from isolation of RBECs to generation of high-resistance/low-permeability RBEC monolayers.
Collapse
Affiliation(s)
- N Joan Abbott
- Institute of Pharmaceutical Science, Blood-Brain Barrier Group, King's College London, London, UK.
| | | | | | | |
Collapse
|
47
|
AL-BADER MD, MALATIALI SA, REDZIC ZB. Expression of Estrogen Receptor α and β in Rat Astrocytes in Primary Culture: Effects of Hypoxia and Glucose Deprivation. Physiol Res 2011; 60:951-60. [DOI: 10.33549/physiolres.932167] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Estrogen replacement therapy could play a role in the reduction of injury associated with cerebral ischemia in vivo, which could be, at least partially, a consequence of estrogen influence of glutamate buffering by astrocytes during hypoxia/ischemia. Estrogen exerts biological effects through interaction with its two receptors: estrogen receptor alpha (ERα) and estrogen receptor beta (ERβ), which are both expressed in astrocytes. This study explored effects of hypoxia and glucose deprivation (HGD), alone or followed by 1 h recovery, on ERα and ERβ expression in primary rat astrocyte cultures following 1 h exposure to: a) 5 % CO2 in air (control group-CG); b) 2 % O2/5 % CO2 in N2 with glucose deprivation (HGD group-HGDG); or c) the HGDG protocol followed by 1 h CG protocol (recovery group-RG). ERα mRNA expression decreased in HGDG. At the protein level, full-length ERα (67 kDa) and three ERα-immunoreactive protein bands (63, 60 and 52 kDa) were detected. A significant decrease in the 52 kDa band was seen in HGDG, while a significant decrease in expression of the full length ERα was seen in the RG. ERβ mRNA and protein expression (a 54 kDa single band) did not change. The observed decrease in ERα protein may limit estrogen-mediated signalling in astrocytes during hypoxia and recovery.
Collapse
Affiliation(s)
| | | | - Z. B. REDZIC
- Department of Physiology, Faculty of Medicine, Kuwait University, Kuwait
| |
Collapse
|
48
|
Glial-conditional deletion of aquaporin-4 (Aqp4) reduces blood-brain water uptake and confers barrier function on perivascular astrocyte endfeet. Proc Natl Acad Sci U S A 2011; 108:17815-20. [PMID: 21990350 DOI: 10.1073/pnas.1110655108] [Citation(s) in RCA: 240] [Impact Index Per Article: 18.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Tissue- and cell-specific deletion of the Aqp4 gene is required to differentiate between the numerous pools of aquaporin-4 (AQP4) water channels. A glial-conditional Aqp4 knockout mouse line was generated to resolve whether astroglial AQP4 controls water exchange across the blood-brain interface. The conditional knockout was driven by the glial fibrillary acidic protein promoter. Brains from conditional Aqp4 knockouts were devoid of AQP4 as assessed by Western blots, ruling out the presence of a significant endothelial pool of AQP4. In agreement, immunofluorescence analysis of cryostate sections and quantitative immunogold analysis of ultrathin sections revealed no AQP4 signals in capillary endothelia. Compared with litter controls, glial-conditional Aqp4 knockout mice showed a 31% reduction in brain water uptake after systemic hypoosmotic stress and a delayed postnatal resorption of brain water. Deletion of astroglial Aqp4 did not affect the barrier function to macromolecules. Our data suggest that the blood-brain barrier (BBB) is more complex than anticipated. Notably, under certain conditions, the astrocyte covering of brain microvessels is rate limiting to water movement.
Collapse
|
49
|
Paul L, Madan M, Rammling M, Chigurupati S, Chan SL, Pattisapu JV. Expression of aquaporin 1 and 4 in a congenital hydrocephalus rat model. Neurosurgery 2011; 68:462-73. [PMID: 21135737 DOI: 10.1227/neu.0b013e3182011860] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Hydrocephalus occurs because of an imbalance of bulk fluid flow in the brain, and aquaporins (AQPs) play pivotal roles in cerebral water movement as essential mediators during edema and fluid accumulation. AQP1 is a water channel found in the choroid plexus (CP), and AQP4 is expressed at the brain-CSF interfaces and astrocytic end feet; excessive fluid accumulation may involve expression of changes in these AQPs during various stages of hydrocephalus. OBJECTIVE To determine the alterations of CP AQP1 expression in congenital hydrocephalus; detect hydrocephalus-induced AQP1 expression in the cortical parenchyma, ependyma, and pia mater of hydrocephalic animals; and evaluate AQP4 expression in congenital hydrocephalus through progressive stages of the condition. METHODS We evaluated differential expression of AQPs 1 and 4 in the congenital hydrocephalus Texas rat at postnatal days 5, 10, and 26 in isolated CP and cortex by enzyme-linked immunosorbent assay, Western blot, quantitative reverse transcriptase polymerase chain reaction, and immunohistochemistry. RESULTS The CP exhibited a 34% decrease in AQP1 expression in young hydrocephalic pups (postnatal days 5 and 10), which became normal (postnatal day 26) just before death. With advancing hydrocephalus, expression of AQPs 1 and 4 increased at the brain-CSF interfaces; AQP1 was localized to the endothelium of cortical capillaries with increased AQP4 expression in surrounding astrocytes end feet. AQP1 expression level was increased in the pia mater, with prominent AQP4 expression in the subpial layers. Subependymal capillaries expressed AQP1 in the endothelium, with increasing AQP4 expression in surrounding astrocytes. Hydrocephalic animals (postnatal day 26) had significant nonendothelial (CD34) AQP1 expression in the septal nucleus of the basal forebrain, an area affected by increased intracranial pressure. CONCLUSION Biphasic AQP1 expression in the CP with increased AQPs 1 and 4 at the brain-fluid interfaces may indicate compensatory mechanisms to regulate choroidal cerebrospinal fluid secretion and increase parenchymal fluid absorption in the high-pressure hydrocephalic condition.
Collapse
Affiliation(s)
- Leena Paul
- Burnett School of Biomedical Science, College of Medicine, University of Central Florida Orlando, Florida, USA.
| | | | | | | | | | | |
Collapse
|
50
|
Bonomini F, Francesca B, Rezzani R. Aquaporin and blood brain barrier. Curr Neuropharmacol 2011; 8:92-6. [PMID: 21119879 PMCID: PMC2923372 DOI: 10.2174/157015910791233132] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2009] [Revised: 03/01/2010] [Accepted: 04/07/2010] [Indexed: 12/25/2022] Open
Abstract
Large water fluxes continuously take place between the different compartments of the brain as well as between the brain parenchyma and the blood or cerebrospinal fluid. Disturbances in this well-regulated water homeostasis may have deleterious effects on brain function and may be fatal in cases where water accumulates in the brain following pathologies such as ischemia, haemorrhage, or brain trauma. The molecular pathways by which water molecules cross the blood brain barrier are not well-understood, although the discovery of Aquaporin 4 (AQP4) in the brain improved the understanding of some of these transport processes, particularly under pathological conditions.
Collapse
Affiliation(s)
- Francesca Bonomini
- Division of Human Anatomy, Department of Biomedical Sciences and Biotechnologies, University of Brescia, V.le Europa 11, 25123 Brescia, Italy
| | | | | |
Collapse
|