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Sahu B, Nookala S, Floden AM, Ambhore NS, Sathish V, Klug MG, Combs CK. House dust mite-induced asthma exacerbates Alzheimer's disease changes in the brain of the App NL-G-F mouse model of disease. Brain Behav Immun 2024; 121:365-383. [PMID: 39084541 DOI: 10.1016/j.bbi.2024.07.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 07/19/2024] [Accepted: 07/28/2024] [Indexed: 08/02/2024] Open
Abstract
Alzheimer's disease (AD) is an age-related neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ) plaques, neuroinflammation, and neuronal death. Besides aging, various comorbidities increase the risk of AD, including obesity, diabetes, and allergic asthma. Epidemiological studies have reported a 2.17-fold higher risk of dementia in asthmatic patients. However, the molecular mechanism(s) underlying this asthma-associated AD exacerbation is unknown. This study was designed to explore house dust mite (HDM)-induced asthma effects on AD-related brain changes using the AppNL-G-F transgenic mouse model of disease. Male and female 8-9 months old C57BL/6J wild type and AppNL-G-F mice were exposed to no treatment, saline sham, or HDM extract every alternate day for 16 weeks for comparison across genotypes and treatment. Mice were euthanized at the end of the experiment, and broncho-alveolar lavage fluid (BALF), blood, lungs, and brains were collected. BALF was used to quantify immune cell phenotype, cytokine levels, total protein content, lactate dehydrogenase (LDH) activity, and total IgE. Lungs were sectioned and stained with hematoxylin and eosin, Alcian blue, and Masson's trichrome. Serum levels of cytokines and soluble Aβ1-40/42 were quantified. Brains were sectioned and immunostained for Aβ, GFAP, CD68, and collagen IV. Finally, frozen hippocampi and temporal cortices were used to perform Aβ ELISAs and cytokine arrays, respectively. HDM exposure led to increased levels of inflammatory cells, cytokines, total protein content, LDH activity, and total IgE in the BALF, as well as increased pulmonary mucus and collagen staining in both sexes and genotypes. Levels of serum cytokines increased in all HDM-exposed groups. Serum from the AppNL-G-F HDM-induced asthma group also had significantly increased soluble Aβ1-42 levels in both sexes. In agreement with this peripheral change, hippocampi from asthma-induced male and female AppNL-G-F mice demonstrated elevated Aβ plaque load and increased soluble Aβ 1-40/42 and insoluble Aβ 1-40 levels. HDM exposure also increased astrogliosis and microgliosis in both sexes of AppNL-G-F mice, as indicated by GFAP and CD68 immunoreactivity, respectively. Additionally, HDM exposure elevated cortical levels of several cytokines in both sexes and genotypes. Finally, HDM-exposed groups also showed a disturbed blood-brain-barrier (BBB) integrity in the hippocampus of AppNL-G-F mice, as indicated by decreased collagen IV immunoreactivity. HDM exposure was responsible for an asthma-like condition in the lungs that exacerbated Aβ pathology, astrogliosis, microgliosis, and cytokine changes in the brains of male and female AppNL-G-F mice that correlated with reduced BBB integrity. Defining mechanisms of asthma effects on the brain may identify novel therapeutic targets for asthma and AD.
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Affiliation(s)
- Bijayani Sahu
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, 1301 N Columbia Road, Grand Forks, ND 58202-9037, USA
| | - Suba Nookala
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, 1301 N Columbia Road, Grand Forks, ND 58202-9037, USA
| | - Angela M Floden
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, 1301 N Columbia Road, Grand Forks, ND 58202-9037, USA
| | - Nilesh S Ambhore
- Department of Pharmaceutical Sciences, School of Pharmacy, College of Health and Human Sciences, North Dakota State University, Fargo, ND 58108-6050, USA
| | - Venkatachalem Sathish
- Department of Pharmaceutical Sciences, School of Pharmacy, College of Health and Human Sciences, North Dakota State University, Fargo, ND 58108-6050, USA
| | - Marilyn G Klug
- Department of Population health, School of Medicine and Health Sciences, USA
| | - Colin K Combs
- Department of Biomedical Sciences, University of North Dakota, School of Medicine and Health Sciences, 1301 N Columbia Road, Grand Forks, ND 58202-9037, USA.
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2
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Wang XF, Vigouroux R, Syonov M, Baglaenko Y, Nikolakopoulou AM, Ringuette D, Rus H, DiStefano PV, Dufour S, Shabanzadeh AP, Lee S, Mueller BK, Charish J, Harada H, Fish JE, Wither J, Wälchli T, Cloutier JF, Zlokovic BV, Carlen PL, Monnier PP. The liver and muscle secreted HFE2-protein maintains central nervous system blood vessel integrity. Nat Commun 2024; 15:1037. [PMID: 38310100 PMCID: PMC10838306 DOI: 10.1038/s41467-024-45303-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Accepted: 01/19/2024] [Indexed: 02/05/2024] Open
Abstract
Liver failure causes breakdown of the Blood CNS Barrier (BCB) leading to damages of the Central-Nervous-System (CNS), however the mechanisms whereby the liver influences BCB-integrity remain elusive. One possibility is that the liver secretes an as-yet to be identified molecule(s) that circulate in the serum to directly promote BCB-integrity. To study BCB-integrity, we developed light-sheet imaging for three-dimensional analysis. We show that liver- or muscle-specific knockout of Hfe2/Rgmc induces BCB-breakdown, leading to accumulation of toxic-blood-derived fibrinogen in the brain, lower cortical neuron numbers, and behavioral deficits in mice. Soluble HFE2 competes with its homologue RGMa for binding to Neogenin, thereby blocking RGMa-induced downregulation of PDGF-B and Claudin-5 in endothelial cells, triggering BCB-disruption. HFE2 administration in female mice with experimental autoimmune encephalomyelitis, a model for multiple sclerosis, prevented paralysis and immune cell infiltration by inhibiting RGMa-mediated BCB alteration. This study has implications for the pathogenesis and potential treatment of diseases associated with BCB-dysfunction.
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Affiliation(s)
- Xue Fan Wang
- Krembil Research Institute, University Health Network, Krembil Discovery Tower, 60 Leonard St.,, Toronto, M5T 2O8, ON, Canada
- Institute of Biomedical and Biomaterial Engineering, University of Toronto, 1 King's College circle,, Toronto, M5S 1A8, ON, Canada
| | - Robin Vigouroux
- Krembil Research Institute, University Health Network, Krembil Discovery Tower, 60 Leonard St.,, Toronto, M5T 2O8, ON, Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College circle,, Toronto, M5S 1A8, ON, Canada
| | - Michal Syonov
- Krembil Research Institute, University Health Network, Krembil Discovery Tower, 60 Leonard St.,, Toronto, M5T 2O8, ON, Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College circle,, Toronto, M5S 1A8, ON, Canada
| | - Yuriy Baglaenko
- Krembil Research Institute, University Health Network, Krembil Discovery Tower, 60 Leonard St.,, Toronto, M5T 2O8, ON, Canada
| | - Angeliki M Nikolakopoulou
- Department of Physiology and Neuroscience, The Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Dene Ringuette
- Krembil Research Institute, University Health Network, Krembil Discovery Tower, 60 Leonard St.,, Toronto, M5T 2O8, ON, Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College circle,, Toronto, M5S 1A8, ON, Canada
| | - Horea Rus
- University of Maryland, School of Medicine, Department of Neurology, Baltimore, MD, 21201, USA
| | - Peter V DiStefano
- Toronto General Hospital Research Institute, University Health Network, 101 College St. Rm 3-308, Toronto, M5L 1L7, ON, Canada
| | - Suzie Dufour
- Krembil Research Institute, University Health Network, Krembil Discovery Tower, 60 Leonard St.,, Toronto, M5T 2O8, ON, Canada
| | - Alireza P Shabanzadeh
- Krembil Research Institute, University Health Network, Krembil Discovery Tower, 60 Leonard St.,, Toronto, M5T 2O8, ON, Canada
| | - Seunggi Lee
- Krembil Research Institute, University Health Network, Krembil Discovery Tower, 60 Leonard St.,, Toronto, M5T 2O8, ON, Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College circle,, Toronto, M5S 1A8, ON, Canada
| | | | - Jason Charish
- Krembil Research Institute, University Health Network, Krembil Discovery Tower, 60 Leonard St.,, Toronto, M5T 2O8, ON, Canada
- Department of Physiology, Faculty of Medicine, University of Toronto, 1 King's College circle,, Toronto, M5S 1A8, ON, Canada
| | - Hidekiyo Harada
- Krembil Research Institute, University Health Network, Krembil Discovery Tower, 60 Leonard St.,, Toronto, M5T 2O8, ON, Canada
| | - Jason E Fish
- Toronto General Hospital Research Institute, University Health Network, 101 College St. Rm 3-308, Toronto, M5L 1L7, ON, Canada
| | - Joan Wither
- Krembil Research Institute, University Health Network, Krembil Discovery Tower, 60 Leonard St.,, Toronto, M5T 2O8, ON, Canada
| | - Thomas Wälchli
- Krembil Research Institute, University Health Network, Krembil Discovery Tower, 60 Leonard St.,, Toronto, M5T 2O8, ON, Canada
- Group of CNS Angiogenesis and Neurovascular Link, and Physician-Scientist Program, Institute for Regenerative Medicine, Neuroscience Center Zurich, and Division of Neurosurgery, University and University Hospital Zurich, Zurich, Switzerland
- Division of Neurosurgery, University Hospital Zurich, Zurich, Switzerland
- Division of Neurosurgery, Department of Surgery, Toronto Western Hospital, University Health Network, Toronto, Canada
| | - Jean-François Cloutier
- The Neuro - Montreal Neurological Institute and Hospital, 3801 Rue Université, Montréal, QC, H3A 2B4, Canada
| | - Berislav V Zlokovic
- Department of Physiology and Neuroscience, The Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Peter L Carlen
- Krembil Research Institute, University Health Network, Krembil Discovery Tower, 60 Leonard St.,, Toronto, M5T 2O8, ON, Canada
- Institute of Biomedical and Biomaterial Engineering, University of Toronto, 1 King's College circle,, Toronto, M5S 1A8, ON, Canada
- Department of Physiology and Neuroscience, The Zilkha Neurogenetic Institute, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Philippe P Monnier
- Krembil Research Institute, University Health Network, Krembil Discovery Tower, 60 Leonard St.,, Toronto, M5T 2O8, ON, Canada.
- Institute of Biomedical and Biomaterial Engineering, University of Toronto, 1 King's College circle,, Toronto, M5S 1A8, ON, Canada.
- Department of Ophthalmology and Vision Sciences, Faculty of Medicine, University of Toronto, 340 College St.,, ON, Toronto, M5T 3A9, Canada.
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3
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Ahmadighadykolaei H, Lambert JA, Raeeszadeh-Sarmazdeh M. TIMP-1 Protects Tight Junctions of Brain Endothelial Cells From MMP-Mediated Degradation. Pharm Res 2023; 40:2121-2131. [PMID: 37700105 PMCID: PMC10878538 DOI: 10.1007/s11095-023-03593-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Accepted: 08/18/2023] [Indexed: 09/14/2023]
Abstract
OBJECTIVE The blood-brain barrier (BBB) plays a critical role in central nervous system homeostasis, and the integrity of BBB is disrupted in many neurodegenerative diseases. Matrix metalloproteinases (MMPs) degrade the tight junctions (TJs) of endothelial cells and basement membrane components essential to BBB integrity, which leads to increased BBB permeability and allows inflammatory cells and neurotoxic substances to enter the brain. Tissue inhibitors of metalloproteinases (TIMPs), endogenous inhibitors of MMPs, regulate MMP activity, thereby maintaining BBB integrity. METHODS The disruptive impacts of MMP-3 and MMP-9 on BBB and protective effect of TIMP-1 were investigated in a simplified in vitro model of the BBB, which was generated using rat brain microvascular endothelial cells (RBMEC). The main features of BBB formation, including permeability and the trans-endothelial electrical resistance (TEER), were monitored over time after the addition of MMP-3 and MMP-9 and their complexes with TIMP-1 inhibitor. RESULTS Our results indicated that MMP-3 and MMP-9 caused a dose-dependent disruption of the BBB, with 1.5 µM MMPs resulting in an over threefold increase in permeability, while TIMP-1 inhibition protected the integrity of the BBB model and recovered TEER and permeability of RBMECs. The disruption and recovery of tight junction proteins of RBMECs after MMP and TIMP treatment were also detected using fluorescent microscopy. CONCLUSION MMP-9 and MMP-3 disrupt the BBB by degrading tight junctions in endothelial cells, and TIMP-1 could inhibit the disruptive effect of MMP-3 and MMP-9 by showing potential as therapeutic protein against MMP-related diseases where BBB disruption plays a role.
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Affiliation(s)
- Hannaneh Ahmadighadykolaei
- Department of Chemical and Materials Engineering, University of Nevada, 1664 N. Virginia St, Reno, NV, 89557, USA
| | - Janet A Lambert
- Department of Chemical and Materials Engineering, University of Nevada, 1664 N. Virginia St, Reno, NV, 89557, USA
- Department of Pharmacology, University of Nevada, Reno School of Medicine, Reno, NV, USA
| | - Maryam Raeeszadeh-Sarmazdeh
- Department of Chemical and Materials Engineering, University of Nevada, 1664 N. Virginia St, Reno, NV, 89557, USA.
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4
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Shahbazi A, Sepehrinezhad A, Vahdani E, Jamali R, Ghasempour M, Massoudian S, Sahab Negah S, Larsen FS. Gut Dysbiosis and Blood-Brain Barrier Alteration in Hepatic Encephalopathy: From Gut to Brain. Biomedicines 2023; 11:1272. [PMID: 37238943 PMCID: PMC10215854 DOI: 10.3390/biomedicines11051272] [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: 02/04/2023] [Revised: 03/20/2023] [Accepted: 03/28/2023] [Indexed: 05/28/2023] Open
Abstract
A common neuropsychiatric complication of advanced liver disease, hepatic encephalopathy (HE), impacts the quality of life and length of hospital stays. There is new evidence that gut microbiota plays a significant role in brain development and cerebral homeostasis. Microbiota metabolites are providing a new avenue of therapeutic options for several neurological-related disorders. For instance, the gut microbiota composition and blood-brain barrier (BBB) integrity are altered in HE in a variety of clinical and experimental studies. Furthermore, probiotics, prebiotics, antibiotics, and fecal microbiota transplantation have been shown to positively affect BBB integrity in disease models that are potentially extendable to HE by targeting gut microbiota. However, the mechanisms that underlie microbiota dysbiosis and its effects on the BBB are still unclear in HE. To this end, the aim of this review was to summarize the clinical and experimental evidence of gut dysbiosis and BBB disruption in HE and a possible mechanism.
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Affiliation(s)
- Ali Shahbazi
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran 1449614535, Iran; (A.S.); (S.M.)
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran 1449614535, Iran;
| | - Ali Sepehrinezhad
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran 1449614535, Iran; (A.S.); (S.M.)
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran 1449614535, Iran;
- Neuroscience Research Center, Mashhad University of Medical Sciences, Mashhad 9919191778, Iran
| | - Edris Vahdani
- Department of Microbiology, Faculty of Medicine, Mazandaran University of Medical Sciences, Sari 4815733971, Iran;
| | - Raika Jamali
- Research Development Center, Sina Hospital, Tehran University of Medical Sciences, Tehran 1417653761, Iran
- Digestive Disease Research Institute, Tehran University of Medical Sciences, Tehran 1417653761, Iran
| | - Monireh Ghasempour
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran 1449614535, Iran;
| | - Shirin Massoudian
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran 1449614535, Iran; (A.S.); (S.M.)
| | - Sajad Sahab Negah
- Neuroscience Research Center, Mashhad University of Medical Sciences, Mashhad 9919191778, Iran
- Department of Neuroscience, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad 9919191778, Iran
- Shefa Neuroscience Research Center, Khatam Alanbia Hospital, Tehran 9815733169, Iran
| | - Fin Stolze Larsen
- Department of Intestinal Failure and Liver Diseases, Rigshospitalet, Inge Lehmanns Vej 5, 2100 Copenhagen, Denmark
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Filipović A, Mašulović D, Gopčević K, Galun D, Igić A, Bulatović D, Zakošek M, Filipović T. Effect of Percutaneous Biliary Drainage on Enzyme Activity of Serum Matrix Metalloproteinase-9 in Patients with Malignant Hilar Obstructive Hyperbilirubinemia. MEDICINA (KAUNAS, LITHUANIA) 2023; 59:medicina59020336. [PMID: 36837539 PMCID: PMC9958900 DOI: 10.3390/medicina59020336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 01/29/2023] [Accepted: 02/05/2023] [Indexed: 02/15/2023]
Abstract
Background and Objectives. Cholestasis activates complex mechanisms of liver injury and as a result has an increased production of matrix metalloproteinases (MMP). Depending on the stage of liver disease, different matrix metalloproteinases expressions have been detected and could serve as indirect biomarkers as well as therapeutic targets. MMP-9 proteolytic activity has a proven role in both liver regeneration and neoplastic cell invasion in various malignancies. The purpose of this prospective cohort study was to evaluate the effect of external biliary drainage on enzyme activity of MMP-9 in the serum of patients with malignant hilar biliary obstruction. Materials and Methods. Between November 2020 and April 2021, 45 patients with malignant hilar biliary obstruction underwent percutaneous biliary drainage following determination of serum MMP-9 enzyme activity (before treatment and 4 weeks after the treatment) by gelatin zymography. Results. MMP-9 values decreased statistically significantly 4 weeks after percutaneous biliary drainage (p = 0.028) as well as the value of total bilirubin (p < 0.001), values of direct bilirubin (p < 0.001), aspartate aminotransferase (AST) (p < 0.001), alanine transaminase (ALT) (p < 0.001), and gamma-glutamyl transferase (GGT) (p < 0.001). Conclusions. In patients with malignant hilar biliary obstruction treated by external percutaneous biliary drainage for cholestasis resolution, a significant reduction in MMP-9 serum values was noted 4 weeks after the treatment.
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Affiliation(s)
- Aleksandar Filipović
- Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
- Center for Radiology, University Clinical Centre of Serbia, 11000 Belgrade, Serbia
| | - Dragan Mašulović
- Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
- Center for Radiology, University Clinical Centre of Serbia, 11000 Belgrade, Serbia
| | - Kristina Gopčević
- Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
- Institute for Chemistry in Medicine, 11000 Belgrade, Serbia
| | - Danijel Galun
- Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
- HPB Unit, Clinic for Digestive Surgery, University Clinical Centre of Serbia, 11000 Belgrade, Serbia
| | - Aleksa Igić
- Center for Radiology, University Clinical Centre of Serbia, 11000 Belgrade, Serbia
| | - Dušan Bulatović
- Center for Radiology, University Clinical Centre of Serbia, 11000 Belgrade, Serbia
| | - Miloš Zakošek
- Center for Radiology, University Clinical Centre of Serbia, 11000 Belgrade, Serbia
| | - Tamara Filipović
- Faculty of Medicine, University of Belgrade, 11000 Belgrade, Serbia
- Institute for Rehabilitation, 11000 Belgrade, Serbia
- Correspondence:
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A critical review of bile acids and their receptors in hepatic encephalopathy. Anal Biochem 2022; 643:114436. [PMID: 34715070 PMCID: PMC9798441 DOI: 10.1016/j.ab.2021.114436] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 09/15/2021] [Accepted: 10/22/2021] [Indexed: 01/01/2023]
Abstract
Hepatic encephalopathy describes an array of neurological complications that arise due to liver insufficiency. The pathogenesis of hepatic encephalopathy shares a longstanding association with hyperammonemia and inflammation, and recently, aberrant bile acid signaling has been implicated in the development of key features of hepatic encephalopathy. These key features include neuronal dysfunction, neuroinflammation and blood-brain barrier permeability. This review summarizes the findings of recent studies demonstrating a role for bile acids in the pathogenesis of hepatic encephalopathy via one of three main bile acid receptors and speculates on the possible downstream consequences of aberrant bile acid signaling.
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Claeys W, Van Hoecke L, Lefere S, Geerts A, Verhelst X, Van Vlierberghe H, Degroote H, Devisscher L, Vandenbroucke RE, Van Steenkiste C. The neurogliovascular unit in hepatic encephalopathy. JHEP Rep 2021; 3:100352. [PMID: 34611619 PMCID: PMC8476774 DOI: 10.1016/j.jhepr.2021.100352] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 07/14/2021] [Accepted: 07/23/2021] [Indexed: 12/14/2022] Open
Abstract
Hepatic encephalopathy (HE) is a neurological complication of hepatic dysfunction and portosystemic shunting. It is highly prevalent in patients with cirrhosis and is associated with poor outcomes. New insights into the role of peripheral origins in HE have led to the development of innovative treatment strategies like faecal microbiota transplantation. However, this broadening of view has not been applied fully to perturbations in the central nervous system. The old paradigm that HE is the clinical manifestation of ammonia-induced astrocyte dysfunction and its secondary neuronal consequences requires updating. In this review, we will use the holistic concept of the neurogliovascular unit to describe central nervous system disturbances in HE, an approach that has proven instrumental in other neurological disorders. We will describe HE as a global dysfunction of the neurogliovascular unit, where blood flow and nutrient supply to the brain, as well as the function of the blood-brain barrier, are impaired. This leads to an accumulation of neurotoxic substances, chief among them ammonia and inflammatory mediators, causing dysfunction of astrocytes and microglia. Finally, glymphatic dysfunction impairs the clearance of these neurotoxins, further aggravating their effect on the brain. Taking a broader view of central nervous system alterations in liver disease could serve as the basis for further research into the specific brain pathophysiology of HE, as well as the development of therapeutic strategies specifically aimed at counteracting the often irreversible central nervous system damage seen in these patients.
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Key Words
- ABC, ATP-binding cassette
- ACLF, acute-on-chronic liver failure
- AD, acute decompensation
- ALF, acute liver failure
- AOM, azoxymethane
- AQP4, aquaporin 4
- Acute Liver Failure
- Ammonia
- BBB, blood-brain barrier
- BCRP, breast cancer resistance protein
- BDL, bile duct ligation
- Blood-brain barrier
- Brain edema
- CCL, chemokine ligand
- CCR, C-C chemokine receptor
- CE, cerebral oedema
- CLD, chronic liver disease
- CLDN, claudin
- CNS, central nervous system
- CSF, cerebrospinal fluid
- Cirrhosis
- Energy metabolism
- GS, glutamine synthetase
- Glymphatic system
- HE, hepatic encephalopathy
- HO-1, heme oxygenase 1
- IL-, interleukin
- MMP-9, matrix metalloproteinase 9
- MRP, multidrug resistance associated protein
- NGVU
- NGVU, neurogliovascular unit
- NKCC1, Na-K-2Cl cotransporter 1
- Neuroinflammation
- OCLN, occludin
- ONS, oxidative and nitrosative stress
- Oxidative stress
- P-gp, P-glycoprotein
- PCA, portacaval anastomosis
- PSS, portosystemic shunt
- S1PR2, sphingosine-1-phosphate receptor 2
- SUR1, sulfonylurea receptor 1
- Systemic inflammation
- TAA, thioacetamide
- TGFβ, transforming growth factor beta
- TJ, tight junction
- TNF, tumour necrosis factor
- TNFR1, tumour necrosis factor receptor 1
- ZO, zonula occludens
- mPT, mitochondrial pore transition
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Affiliation(s)
- Wouter Claeys
- Hepatology Research Unit, Department of Internal Medicine and Paediatrics, Liver Research Center Ghent, Ghent University, Ghent, Belgium
- Barriers in Inflammation, VIB Center for Inflammation Research, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Lien Van Hoecke
- Barriers in Inflammation, VIB Center for Inflammation Research, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Sander Lefere
- Hepatology Research Unit, Department of Internal Medicine and Paediatrics, Liver Research Center Ghent, Ghent University, Ghent, Belgium
- Gut-Liver Immunopharmacology Unit, Department of Basic and Applied Medical Sciences; Liver Research Center Ghent; Ghent University, Ghent, Belgium
| | - Anja Geerts
- Hepatology Research Unit, Department of Internal Medicine and Paediatrics, Liver Research Center Ghent, Ghent University, Ghent, Belgium
| | - Xavier Verhelst
- Hepatology Research Unit, Department of Internal Medicine and Paediatrics, Liver Research Center Ghent, Ghent University, Ghent, Belgium
| | - Hans Van Vlierberghe
- Hepatology Research Unit, Department of Internal Medicine and Paediatrics, Liver Research Center Ghent, Ghent University, Ghent, Belgium
| | - Helena Degroote
- Hepatology Research Unit, Department of Internal Medicine and Paediatrics, Liver Research Center Ghent, Ghent University, Ghent, Belgium
| | - Lindsey Devisscher
- Gut-Liver Immunopharmacology Unit, Department of Basic and Applied Medical Sciences; Liver Research Center Ghent; Ghent University, Ghent, Belgium
| | - Roosmarijn E. Vandenbroucke
- Barriers in Inflammation, VIB Center for Inflammation Research, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Christophe Van Steenkiste
- Antwerp University, Department of Gastroenterology and Hepatology, Antwerp, Belgium
- Department of Gastroenterology and Hepatology, Maria Middelares Hospital, Ghent, Belgium
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Kim YK, Song J. Therapeutic Applications of Resveratrol in Hepatic Encephalopathy through Its Regulation of the Microbiota, Brain Edema, and Inflammation. J Clin Med 2021; 10:jcm10173819. [PMID: 34501267 PMCID: PMC8432232 DOI: 10.3390/jcm10173819] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/22/2021] [Accepted: 08/24/2021] [Indexed: 02/07/2023] Open
Abstract
Hepatic encephalopathy is a common complication in patients with liver cirrhosis and portosystemic shunting. Patients with hepatic encephalopathy present a variety of clinical features, including neuropsychiatric manifestations, cognitive dysfunction, impaired gut barrier function, hyperammonemia, and chronic neuroinflammation. These pathogeneses have been linked to various factors, including ammonia-induced oxidative stress, neuronal cell death, alterations in the gut microbiome, astrocyte swelling, and blood-brain barrier disruptions. Many researchers have focused on identifying novel therapeutics and prebiotics in the hope of improving the treatment of these conditions. Resveratrol is a natural polyphenic compound and is known to exert several pharmacological effects, including antioxidant, anti-inflammatory, and neuroprotective activities. Recent studies suggest that resveratrol contributes to improving the neuropathogenic effects of liver failure. Here, we review the current evidence describing resveratrol's effects in neuropathogenesis and its impact on the gut-liver axis relating to hepatic encephalopathy. We highlight the hypothesis that resveratrol exerts diverse effects in hepatic encephalopathy and suggest that these effects are likely mediated by changes to the gut microbiota, brain edema, and neuroinflammation.
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Affiliation(s)
- Young-Kook Kim
- Department of Biochemistry, Chonnam National University Medical School, Hwasun 58128, Jeollanam-do, Korea;
| | - Juhyun Song
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Jeollanam-do, Korea
- Correspondence: ; Tel.: +82-61-379-2706; Fax: +82-61-375-5834
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9
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DeMorrow S, Cudalbu C, Davies N, Jayakumar AR, Rose CF. 2021 ISHEN guidelines on animal models of hepatic encephalopathy. Liver Int 2021; 41:1474-1488. [PMID: 33900013 PMCID: PMC9812338 DOI: 10.1111/liv.14911] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 03/05/2021] [Accepted: 04/01/2021] [Indexed: 02/07/2023]
Abstract
This working group of the International Society of Hepatic Encephalopathy and Nitrogen Metabolism (ISHEN) was commissioned to summarize and update current efforts in the development and characterization of animal models of hepatic encephalopathy (HE). As defined in humans, HE in animal models is based on the underlying degree and severity of liver pathology. Although hyperammonemia remains the key focus in the pathogenesis of HE, other factors associated with HE have been identified, together with recommended animal models, to help explore the pathogenesis and pathophysiological mechanisms of HE. While numerous methods to induce liver failure and disease exist, less have been characterized with neurological and neurobehavioural impairments. Moreover, there still remains a paucity of adequate animal models of Type C HE induced by alcohol, viruses and non-alcoholic fatty liver disease; the most common etiologies of chronic liver disease.
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Affiliation(s)
- S DeMorrow
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Texas, USA; Department of Internal Medicine, Dell Medical School, The University of Texas at Austin, Texas, USA; Research division, Central Texas Veterans Healthcare System, Temple Texas USA.,Correspondance: Sharon DeMorrow, PhD, ; tel: +1-512-495-5779
| | - C Cudalbu
- Center for Biomedical Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - N Davies
- Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, United Kingdom
| | - AR Jayakumar
- General Medical Research, Neuropathology Section, R&D Service and South Florida VA Foundation for Research and Education Inc; Obstetrics, Gynecology and Reproductive Sciences, University of Miami School of Medicine, Miami FL, USA
| | - CF Rose
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montreal, Canada
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10
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The Cerebral Effect of Ammonia in Brain Aging: Blood-Brain Barrier Breakdown, Mitochondrial Dysfunction, and Neuroinflammation. J Clin Med 2021; 10:jcm10132773. [PMID: 34202669 PMCID: PMC8268635 DOI: 10.3390/jcm10132773] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 06/23/2021] [Accepted: 06/23/2021] [Indexed: 12/14/2022] Open
Abstract
Aging occurs along with multiple pathological problems in various organs. The aged brain, especially, shows a reduction in brain mass, neuronal cell death, energy dysregulation, and memory loss. Brain aging is influenced by altered metabolites both in the systemic blood circulation and the central nervous system (CNS). High levels of ammonia, a natural by-product produced in the body, have been reported as contributing to inflammatory responses, energy metabolism, and synaptic function, leading to memory function in CNS. Ammonia levels in the brain also increase as a consequence of the aging process, ultimately leading to neuropathological problems in the CNS. Although many researchers have demonstrated that the level of ammonia in the body alters with age and results in diverse pathological alterations, the definitive relationship between ammonia and the aged brain is not yet clear. Thus, we review the current body of evidence related to the roles of ammonia in the aged brain. On the basis of this, we hypothesize that the modulation of ammonia level in the CNS may be a critical clinical point to attenuate neuropathological alterations associated with aging.
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11
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Czarnecka AM, Milewski K, Albrecht J, Zielińska M. The Status of Bile Acids and Farnesoid X Receptor in Brain and Liver of Rats with Thioacetamide-Induced Acute Liver Failure. Int J Mol Sci 2020; 21:ijms21207750. [PMID: 33092050 PMCID: PMC7589210 DOI: 10.3390/ijms21207750] [Citation(s) in RCA: 7] [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: 09/30/2020] [Revised: 10/16/2020] [Accepted: 10/19/2020] [Indexed: 12/14/2022] Open
Abstract
Acute liver failure (ALF) leads to neurological symptoms defined as hepatic encephalopathy (HE). Although accumulation of ammonia and neuroinflammation are generally accepted as main contributors to HE pathomechanism, a buildup of bile acids (BA) in the blood is a frequent component of liver injury in HE patients. Recent studies have identified the nuclear farnesoid X receptor (FXR) acting via small heterodimer partner (SHP) as a mediator of BA-induced effects in the brain of ALF animals. The present study investigated the status of the BA–FXR axis in the brain and the liver, including selective changes in pertinent genes in thioacetamide (TAA)-induced ALF in Sprague–Dawley rats. FXR was found in rat neurons, confirming earlier reports for mouse and human brain. BA accumulated in blood but not in the brain tissue. Expression of mRNAs coding for Fxr and Shp was reduced in the hippocampus and of Fxr mRNA also in the cerebellum. Changes in Fxr mRNA levels were not followed by changes in FXR protein. The results leave open the possibility that mobilization of the BA–FXR axis in the brain may not be necessarily pathognomonic to HE but may depend upon ALF-related confounding factors.
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Affiliation(s)
- Anna Maria Czarnecka
- Correspondence: (A.M.C.); (M.Z.); Tel.: +48-22-6086416 (A.M.C.); +48-22-6086470 (M.Z.)
| | | | | | - Magdalena Zielińska
- Correspondence: (A.M.C.); (M.Z.); Tel.: +48-22-6086416 (A.M.C.); +48-22-6086470 (M.Z.)
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12
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Liu ZH, Chen NY, Tu PH, Wu CT, Chiu SC, Huang YC, Lim SN, Yip PK. DHA Attenuates Cerebral Edema Following Traumatic Brain Injury via the Reduction in Blood-Brain Barrier Permeability. Int J Mol Sci 2020; 21:ijms21176291. [PMID: 32878052 PMCID: PMC7503959 DOI: 10.3390/ijms21176291] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Accepted: 08/27/2020] [Indexed: 12/12/2022] Open
Abstract
Traumatic brain injury (TBI) could result in edema and cause an increase in intracranial pressure of the brain resulting in mortality and morbidity. Although there is hyperosmolarity therapy available for this pathophysiological event, it remains controversial. Recently, several groups have shown docosahexaenoic acid (DHA) to improve functional and histological outcomes following brain injury based on reduction of neuroinflammation and apoptosis. However, the effect of DHA on blood-brain barrier (BBB) dysfunction after brain injury has not been fully studied. Here, a controlled cortical impact rat model was used to test the effect of a single dose of DHA administered 30 min post injury. Modified neurological severity score (mNSS) and forelimb asymmetry were used to determine the functional outcomes. Neuroimaging and histology were used to characterize the edema and BBB dysfunction. The study showed that DHA-treated TBI rats had better mNSS and forelimb asymmetry score than vehicle-treated TBI rats. Temporal analysis of edema using MRI revealed a significant reduction in edema level with DHA treatment compared to vehicle in TBI rats. Histological analysis using immunoglobulin G (IgG) extravasation showed that there was less extravasation, which corresponded with a reduction in aquaporin 4 and astrocytic metalloprotease 9 expression, and greater endothelial occludin expression in the peri-contusional site of the TBI rat brain treated with DHA in comparison to vehicle treatment. In conclusion, the study shows that DHA can exert its functional improvement by prevention of the edema formation via prevention of BBB dysfunction after TBI.
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Affiliation(s)
- Zhuo-Hao Liu
- Department of Neurosurgery, Chang Gung Memorial Hospital at Linkou, Chang Gung Medical College and University, Taoyuan County 333, Taiwan; (P.-h.T.); (Y.-C.H.)
- Correspondence: (Z.-H.L.); (P.K.Y.)
| | - Nan-Yu Chen
- Department of Internal Medicine, Chang Gung Memorial Hospital at Linkou, Chang Gung Medical College and University, Taoyuan County 333, Taiwan;
| | - Po-hsun Tu
- Department of Neurosurgery, Chang Gung Memorial Hospital at Linkou, Chang Gung Medical College and University, Taoyuan County 333, Taiwan; (P.-h.T.); (Y.-C.H.)
| | - Chen-Te Wu
- Department of Medical Imaging and Intervention, Chang Gung Memorial Hospital at Linkou, Chang Gung Medical College and University, Taoyuan County 333, Taiwan;
| | - Shao-Chieh Chiu
- Center for Advanced Molecular Imaging and Translation, Chang Gung Memorial Hospital at Linkou, Taoyuan County 333, Taiwan;
| | - Ying-Cheng Huang
- Department of Neurosurgery, Chang Gung Memorial Hospital at Linkou, Chang Gung Medical College and University, Taoyuan County 333, Taiwan; (P.-h.T.); (Y.-C.H.)
| | - Siew-Na Lim
- Department of Neurology, Chang Gung Memorial Hospital at Linkou, Chang Gung Medical College and University, Taoyuan County 333, Taiwan;
| | - Ping K. Yip
- Queen Mary University of London, Barts and The London School of Medicine and Dentistry, Blizard Institute, Centre for Neuroscience, Surgery & Trauma, London E1 2AT, UK
- Correspondence: (Z.-H.L.); (P.K.Y.)
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13
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Geervliet E, Bansal R. Matrix Metalloproteinases as Potential Biomarkers and Therapeutic Targets in Liver Diseases. Cells 2020; 9:E1212. [PMID: 32414178 PMCID: PMC7290342 DOI: 10.3390/cells9051212] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 05/06/2020] [Accepted: 05/13/2020] [Indexed: 01/18/2023] Open
Abstract
Chronic liver diseases, characterized by an excessive accumulation of extracellular matrix (ECM) resulting in scar tissue formation, are a growing health problem causing increasing morbidity and mortality worldwide. Currently, therapeutic options for tissue fibrosis are severely limited, and organ transplantation is the only treatment for the end-stage liver diseases. During liver damage, injured hepatocytes release proinflammatory factors resulting in the recruitment and activation of immune cells that activate quiescent hepatic stellate cells (HSCs). Upon activation, HSCs transdifferentiate into highly proliferative, migratory, contractile and ECM-producing myofibroblasts. The disrupted balance between ECM deposition and degradation leads to the formation of scar tissue referred to as fibrosis. This balance can be restored either by reducing ECM deposition (by inhibition of HSCs activation and proliferation) or enhancing ECM degradation (by increased expression of matrix metalloproteinases (MMPs)). MMPs play an important role in ECM remodeling and represent an interesting target for therapeutic drug discovery. In this review, we present the current knowledge about ECM remodeling and role of the different MMPs in liver diseases. MMP expression patterns in different stages of liver diseases have also been reviewed to determine their role as biomarkers. Finally, we highlight MMPs as promising therapeutic targets for the resolution of liver diseases.
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Affiliation(s)
| | - Ruchi Bansal
- Translational Liver Research, Department of Medical Cell BioPhysics, Technical Medical Centre, Faculty of Science and Technology, University of Twente, 7522 NB Enschede, The Netherlands;
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14
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Liotta EM, Kimberly WT. Cerebral edema and liver disease: Classic perspectives and contemporary hypotheses on mechanism. Neurosci Lett 2020; 721:134818. [PMID: 32035166 DOI: 10.1016/j.neulet.2020.134818] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 02/01/2020] [Accepted: 02/03/2020] [Indexed: 02/07/2023]
Abstract
Liver disease is a growing public health concern. Hepatic encephalopathy, the syndrome of brain dysfunction secondary to liver disease, is a frequent complication of both acute and chronic liver disease and cerebral edema (CE) is a key feature. While altered ammonia metabolism is a key contributor to hepatic encephalopathy and CE in liver disease, there is a growing appreciation that additional mechanisms contribute to CE. In this review we will begin by presenting three classic perspectives that form a foundation for a discussion of CE in liver disease: 1) CE is unique to acute liver failure, 2) CE in liver disease is only cytotoxic, and 3) CE in liver disease is primarily an osmotically mediated consequence of ammonia and glutamine metabolism. We will present each classic perspective along with more recent observations that call in to question that classic perspective. After highlighting these areas of debate, we will explore the leading contemporary mechanisms hypothesized to contribute to CE during liver disease.
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Affiliation(s)
- Eric M Liotta
- Northwestern University-Feinberg School of Medicine, Department of Neurology, United States; Northwestern University-Feinberg School of Medicine, Department of Surgery, Division of Organ Transplantation, United States; Northwestern University Transplant Outcomes Research Collaboration, United States.
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15
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Halstead MR, Geocadin RG. The Medical Management of Cerebral Edema: Past, Present, and Future Therapies. Neurotherapeutics 2019; 16:1133-1148. [PMID: 31512062 PMCID: PMC6985348 DOI: 10.1007/s13311-019-00779-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Cerebral edema is commonly associated with cerebral pathology, and the clinical manifestation is largely related to the underlying lesioned tissue. Brain edema usually amplifies the dysfunction of the lesioned tissue and the burden of cerebral edema correlates with increased morbidity and mortality across diseases. Our modern-day approach to the medical management of cerebral edema has largely revolved around, an increasingly artificial distinction between cytotoxic and vasogenic cerebral edema. These nontargeted interventions such as hyperosmolar agents and sedation have been the mainstay in clinical practice and offer noneloquent solutions to a dire problem. Our current understanding of the underlying molecular mechanisms driving cerebral edema is becoming much more advanced, with differences being identified across diseases and populations. As our understanding of the underlying molecular mechanisms in neuronal injury continues to expand, so too is the list of targeted therapies in the pipeline. Here we present a brief review of the molecular mechanisms driving cerebral edema and a current overview of our understanding of the molecular targets being investigated.
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Affiliation(s)
- Michael R Halstead
- Neurosciences Critical Care Division, Departments of Neurology, Anesthesiology-Critical Care Medicine and Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21287, USA.
| | - Romergryko G Geocadin
- Neurosciences Critical Care Division, Departments of Neurology, Anesthesiology-Critical Care Medicine and Neurosurgery, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21287, USA
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16
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Deák F, Anderson RE, Fessler JL, Sherry DM. Novel Cellular Functions of Very Long Chain-Fatty Acids: Insight From ELOVL4 Mutations. Front Cell Neurosci 2019; 13:428. [PMID: 31616255 PMCID: PMC6763723 DOI: 10.3389/fncel.2019.00428] [Citation(s) in RCA: 66] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 09/06/2019] [Indexed: 12/22/2022] Open
Abstract
Elongation of Very Long chain fatty acids-4 (ELOVL4) protein is a member of the ELOVL family of fatty acid elongases that is collectively responsible for catalyzing formation of long chain fatty acids. ELOVL4 is the only family member that catalyzes production of Very Long Chain Saturated Fatty Acids (VLC-SFA) and Very Long Chain Polyunsaturated Fatty Acids (VLC-PUFA) with chain lengths ≥28 carbons. ELOVL4 and its VLC-SFA and VLC-PUFA products are emerging as important regulators of synaptic signaling and neuronal survival in the central nervous system (CNS). Distinct sets of mutations in ELOVL4 cause three different neurological diseases in humans. Heterozygous inheritance of one set of autosomal dominant ELOVL4 mutations that leads to truncation of the ELOVL4 protein causes Stargardt-like macular dystrophy (STGD3), an aggressive juvenile-onset retinal degeneration. Heterozygous inheritance of a different set of autosomal dominant ELOVL4 mutations that leads to a full-length protein with single amino acid substitutions causes spinocerebellar ataxia 34 (SCA34), a late-onset neurodegenerative disease characterized by gait ataxia and cerebellar atrophy. Homozygous inheritance of a different set of ELOVL4 mutations causes a more severe disease with infantile onset characterized by seizures, spasticity, intellectual disability, ichthyosis, and premature death. ELOVL4 is expressed widely in the CNS and is found primarily in neurons. ELOVL4 is expressed in cell-specific patterns within different regions of the CNS that are likely to be related to disease symptoms. In the retina, ELOVL4 is expressed exclusively in photoreceptors and produces VLC-PUFA that are incorporated into phosphatidylcholine and enriched in the light sensitive membrane disks of the photoreceptor outer segments. VLC-PUFA are enzymatically converted into "elovanoid" compounds that appear to provide paracrine signals that promote photoreceptor and neuronal survival. In the brain, the main ELOVL4 products are VLC-SFA that are incorporated into sphingolipids and enriched in synaptic vesicles, where they regulate kinetics of presynaptic neurotransmitter release. Understanding the function of ELOVL4 and its VLC-SFA and VLC-PUFA products will advance our understanding of basic mechanisms in neural signaling and has potential for developing novel therapies for seizure and neurodegenerative diseases.
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Affiliation(s)
- Ferenc Deák
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Harold Hamm Diabetes Center, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Robert E Anderson
- Department of Geriatric Medicine, Reynolds Oklahoma Center on Aging, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Dean McGee Eye Institute, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - Jennifer L Fessler
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
| | - David M Sherry
- Oklahoma Center for Neurosciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States.,Department of Pharmaceutical Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, United States
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Abstract
Hepatic encephalopathy describes the array of neurological complications that arise due to liver insufficiency and/or portal-systemic shunt. The pathogenesis of hepatic encephalopathy shares a longstanding association with hyperammonemia and inflammation. Recently, aberrant bile acid signaling has been implicated in the development of key features of hepatic encephalopathy due to acute liver failure including neuronal dysfunction, neuroinflammation and blood-brain barrier permeability. This review summarizes the findings of recent studies demonstrating a role for bile acids in hepatic encephalopathy and speculates on the possible downstream consequences of bile acid signaling.
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Key Words
- ASBT, Apical Sodium-Dependent Bile Acid Transporter
- CCL2, Chemokine Ligand 2
- CCR2, Chemokine Receptor 2
- Cyp46A1, Cytochrome p450 46A1
- FXR, Farnesoid X Receptor
- GR, Glucocorticoid Receptor
- NTCP, Sodium Taurocholate Cotransporting Polypeptide
- PXR, Pregnane X Receptor
- S1P2R, Sphingosine 1 Phosphate Receptor 2
- TGR5, Takeda G-Protein Receptor 5
- Takeda G-protein coupled receptor 5 (TGR5)
- VDR, Vitamin D Receptor
- blood–brain barrier
- farnesoid X receptor
- neuroinflammation
- sphingosine-1-phosphate receptor 2
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18
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Weiss N, Housset C, Thabut D. Hepatic encephalopathy: Another brick in the wall. J Hepatol 2019; 70:8-10. [PMID: 30414737 DOI: 10.1016/j.jhep.2018.10.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/09/2018] [Revised: 10/18/2018] [Accepted: 10/21/2018] [Indexed: 12/12/2022]
Affiliation(s)
- Nicolas Weiss
- Sorbonne Université, Brain Liver Pitié-Salpêtrière (BLIPS) Study Group, Assistance Publique - Hôpitaux de Paris, Groupement Hospitalier Pitié-Salpêtrière-Charles Foix, Département de Neurologie, Unité de réanimation neurologique, Paris, France; Sorbonne Université, INSERM, Centre de Recherche Saint-Antoine (CRSA), Paris, France.
| | - Chantal Housset
- Sorbonne Université, INSERM, Centre de Recherche Saint-Antoine (CRSA), Paris, France
| | - Dominique Thabut
- Sorbonne Université, INSERM, Centre de Recherche Saint-Antoine (CRSA), Paris, France; Sorbonne Université, Brain Liver Pitié-Salpêtrière (BLIPS) Study Group, Assistance Publique - Hôpitaux de Paris, Groupement Hospitalier Pitié-Salpêtrière-Charles Foix, Service d'Hépato-Gastroentérologie, Unité de Soins Intensifs d'Hépato-Gastroentérologie, Paris, France
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19
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GABA, γ-Aminobutyric Acid, Protects Against Severe Liver Injury. J Surg Res 2018; 236:172-183. [PMID: 30694753 DOI: 10.1016/j.jss.2018.11.047] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 11/01/2018] [Accepted: 11/21/2018] [Indexed: 12/24/2022]
Abstract
BACKGROUND Acute liver failure (ALF) from severe acute liver injury is a critical condition associated with high mortality. The purpose of this study was to investigate the impact of preemptive administration of γ-aminobutyric acid (GABA) on hepatic injury and survival outcomes in mice with experimentally induced ALF. MATERIALS AND METHODS To induce ALF, C57BL/6NHsd mice were administered GABA, saline, or nothing for 7 d, followed by intraperitoneal administration of 500 μg of tumor necrosis factor α and 20 mg of D-galactosamine. The study mice were humanely euthanized 4-5 h after ALF was induced or observed for survival. Proteins present in the blood samples and liver tissue from the euthanized mice were analyzed using Western blot and immunohistochemical and histopathologic analyses. For inhibition studies, we administered the STAT3-specific inhibitor, NSC74859, 90 min before ALF induction. RESULTS We found that GABA-treated mice had substantial attenuation of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive hepatocytes and hepatocellular necrosis, decreased caspase-3, H2AX, and p38 MAPK protein levels and increased expressions of Jak2, STAT3, Bcl-2, and Mn-SOD, with improved mitochondrial integrity. The reduced apoptotic proteins led to a significantly prolonged survival after ALF induction in GABA-treated mice. The STAT3-specific inhibitor NSC74859 eliminated the survival advantage in GABA-treated mice with ALF, indicating the involvement of the STAT3 pathway in GABA-induced reduction in apoptosis. CONCLUSIONS Our results showed that preemptive treatment with GABA protected against severe acute liver injury in mice via GABA-mediated STAT3 signaling. Preemptive administration of GABA may be a useful approach to optimize marginal donor livers before transplantation.
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20
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Two hit induced acute lung injury impairs cognitive function in mice: A potential model to study cross talk between lung and brain. Brain Behav Immun 2018; 73:633-642. [PMID: 30026058 DOI: 10.1016/j.bbi.2018.07.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 07/06/2018] [Accepted: 07/14/2018] [Indexed: 01/12/2023] Open
Abstract
Acute lung injury (ALI), a pulmonary inflammatory disorder, is associated with high morbidity and mortality rates. Interestingly, ALI survivors have been reported for some neurocognitive deterioration at/after discharge. However, the molecular factors behind such extra pulmonary manifestation are not clearly known. The present work was designed to investigate lung-brain cross talk in experimental mice for deciphering primary molecular factors that may be involved in ALI-mediated cognitive impairment. ALI was induced in Balb/c mice by intra-tracheal administration of either 0.1 N HCl (2 ml/kg) or LPS (1 mg/kg) as single hits or both agents were administered successively to mimic the 'two hit' model. Interestingly two hit-mediated ALI resulted in exaggerated inflammatory response as reflected by increased pulmonary neutrophils and inflammatory factors (TNF-α/IL-1β/IL-6). Additionally, two hits resulted in delayed resolution of lung inflammation and was coupled with persistent decline in memory, as assessed by Morris water maze test. Further, two hits elevate serum levels of TNF-α/IL-1β which was associated with compromised blood brain barrier (BBB), as evident by decreased expression of occludin/claudin-5 and consequent Evans-blue extravasation in hippocampus 1 week post injury. Finally, dexamethasone protects against the two hit mediated cognitive impairment by lowering the pro-inflammatory factors (TNF-α/IL-1β) both in lungs and blood. Overall, we report for the first time that 'two hit' mediated ALI cause persistent cognitive impairment in mice partly via up-regulating systemic expression of TNF-α/IL-1β that may disrupt BBB and hence the model may be a useful tool to examine the lung-brain cross-talk at the molecular level for exploring newer therapeutics.
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21
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Fan Y, Liu X. Alterations in Expression and Function of ABC Family Transporters at Blood-Brain Barrier under Liver Failure and Their Clinical Significances. Pharmaceutics 2018; 10:pharmaceutics10030102. [PMID: 30041501 PMCID: PMC6161250 DOI: 10.3390/pharmaceutics10030102] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2018] [Revised: 07/20/2018] [Accepted: 07/21/2018] [Indexed: 02/07/2023] Open
Abstract
Liver failure is often associated with hepatic encephalopathy, due to dyshomeostasis of the central nervous system (CNS). Under physiological conditions, the CNS homeostasis is precisely regulated by the blood-brain barrier (BBB). The BBB consists of brain microvessel endothelial cells connected with a junctional complex by the adherens junctions and tight junctions. Its main function is to maintain brain homoeostasis via limiting the entry of drugs/toxins to brain. The brain microvessel endothelial cells are characterized by minimal pinocytotic activity, absent fenestrations, and highly expressions of ATP-binding cassette (ABC) family transporters (such as P-glycoprotein, breast cancer resistance protein and multidrug resistance-associated proteins). These ABC transporters prevent brain from toxin accumulation by pumping toxins out of brain. Accumulating evidences demonstrates that liver failure diseases altered the expression and function of ABC transporters at The BBB, indicating that the alterations subsequently affect drugs’ brain distribution and CNS activity/neurotoxicity. ABC transporters also mediate the transport of endogenous substrates across the BBB, inferring that ABC transporters are also implicated in some physiological processes and the development of hepatic encephalopathy. This paper focuses on the alteration in the BBB permeability, the expression and function of ABC transporters at the BBB under liver failure status and their clinical significances.
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Affiliation(s)
- Yilin Fan
- Center of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009, China.
| | - Xiaodong Liu
- Center of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing 210009, China.
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22
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Lysophosphatidic acid receptor, LPA 6, regulates endothelial blood-brain barrier function: Implication for hepatic encephalopathy. Biochem Biophys Res Commun 2018; 501:1048-1054. [PMID: 29778535 DOI: 10.1016/j.bbrc.2018.05.106] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Accepted: 05/15/2018] [Indexed: 11/22/2022]
Abstract
Cerebral edema is a life-threatening neurological condition characterized by brain swelling due to the accumulation of excess fluid both intracellularly and extracellularly. Fulminant hepatic failure (FHF) develops cerebral edema by disrupting blood-brain barrier (BBB). However, the mechanisms by which mediator induces brain edema in FHF remain to be elucidated. Here, we assessed a linkage between brain edema and lysophosphatidic acid (LPA) signaling by utilizing an animal model of FHF and in vitro BBB model. Azoxymethane-treated mice developed FHF and hepatic encephalopathy, associated with higher autotaxin (ATX) activities in serum than controls. Using in vitro BBB model, LPA disrupted the structural integrity of tight junction proteins including claudin-5, occludin, and ZO-1. Furthermore, LPA decreased transendothelial electrical resistances in in vitro BBB model, and induced cell contraction in brain endothelial monolayer cultures, both being inhibited by a Rho-associated protein kinase inhibitor, Y-27632. The brain capillary endothelial cells predominantly expressed LPA6 mRNA, whose knockdown blocked the LPA-induced endothelial cell contraction. Taken together, the up-regulation of serum ATX in hepatic encephalopathy may activate the LPA-LPA6-G12/13-Rho pathway in brain capillary endothelial cells, leading to enhancement of BBB permeability and brain edema.
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Obara-Michlewska M, Ding F, Popek M, Verkhratsky A, Nedergaard M, Zielinska M, Albrecht J. Interstitial ion homeostasis and acid-base balance are maintained in oedematous brain of mice with acute toxic liver failure. Neurochem Int 2018; 118:286-291. [PMID: 29772253 DOI: 10.1016/j.neuint.2018.05.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2018] [Revised: 05/11/2018] [Accepted: 05/13/2018] [Indexed: 01/25/2023]
Abstract
Acute toxic liver failure (ATLF) rapidly leads to brain oedema and neurological decline. We evaluated the ability of ATLF-affected brain to control the ionic composition and acid-base balance of the interstitial fluid. ATLF was induced in 10-12 weeks old male C57Bl mice by single intraperitoneal (i.p.) injection of 100 μg/g azoxymethane (AOM). Analyses were carried out in cerebral cortex of precomatous mice 20-24 h after AOM administration. Brain fluid status was evaluated by measuring apparent diffusion coefficient [ADC] using NMR spectroscopy, Evans Blue extravasation, and accumulation of an intracisternally-injected fluorescent tracer. Extracellular pH ([pH]e) and ([K+]e) were measured in situ with ion-sensitive microelectrodes. Cerebral cortical microdialysates were subjected to photometric analysis of extracellular potassium ([K+]e), sodium ([Na+]e) and luminometric assay of extracellular lactate ([Lac]e). Potassium transport in cerebral cortical slices was measured ex vivo as 86Rb uptake. Cerebral cortex of AOM-treated mice presented decreased ADC supporting the view that ATLF-induced brain oedema is primarily cytotoxic in nature. In addition, increased Evans blue extravasation indicated blood brain barrier leakage, and increased fluorescent tracer accumulation suggested impaired interstitial fluid passage. However, [K+]e, [Na+]e, [Lac]e, [pH]e and potassium transport in brain of AOM-treated mice was not different from control mice. We conclude that in spite of cytotoxic oedema and deregulated interstitial fluid passage, brain of mice with ATLF retains the ability to maintain interstitial ion homeostasis and acid-base balance. Tentatively, uncompromised brain ion homeostasis and acid-base balance may contribute to the relatively frequent brain function recovery and spontaneous survival rate in human patients with ATLF.
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Affiliation(s)
- Marta Obara-Michlewska
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawińskiego St, 02-106 Warsaw, Poland.
| | - Fengfei Ding
- Center for Translational Neuromedicine, University of Rochester, NY, USA
| | - Mariusz Popek
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawińskiego St, 02-106 Warsaw, Poland
| | - Alexei Verkhratsky
- Faculty of Life Sciences, University of Manchester, UK; Achucarro Center for Neuroscience, IKERBASQUE, Basque Foundation for Science, 48011 Bilbao, Spain
| | - Maiken Nedergaard
- Center for Translational Neuromedicine, University of Rochester, NY, USA
| | - Magdalena Zielinska
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawińskiego St, 02-106 Warsaw, Poland
| | - Jan Albrecht
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, 5 Pawińskiego St, 02-106 Warsaw, Poland.
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McMillin M, Grant S, Frampton G, Petrescu AD, Kain J, Williams E, Haines R, Canady L, DeMorrow S. FXR-Mediated Cortical Cholesterol Accumulation Contributes to the Pathogenesis of Type A Hepatic Encephalopathy. Cell Mol Gastroenterol Hepatol 2018; 6:47-63. [PMID: 29928671 PMCID: PMC6008252 DOI: 10.1016/j.jcmgh.2018.02.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Accepted: 02/26/2018] [Indexed: 12/13/2022]
Abstract
BACKGROUND & AIMS Hepatic encephalopathy is a serious neurologic complication of acute and chronic liver diseases. We previously showed that aberrant bile acid signaling contributes to the development of hepatic encephalopathy via farnesoid X receptor (FXR)-mediated mechanisms in neurons. In the brain, a novel alternative bile acid synthesis pathway, catalyzed by cytochrome p450 46A1 (Cyp46A1), is the primary mechanism by which the brain regulates cholesterol homeostasis. The aim of this study was to determine if FXR activation in the brain altered cholesterol homeostasis during hepatic encephalopathy. METHODS Cyp7A1-/- mice or C57Bl/6 mice pretreated with central infusion of FXR vivo morpholino, 2-hydroxypropyl-β-cyclodextrin, or fed a cholestyramine-supplemented diet were injected with azoxymethane (AOM). Cognitive and neuromuscular impairment as well as liver damage and expression of Cyp46A1 were assessed using standard techniques. The subsequent cholesterol content in the frontal cortex was measured using commercially available kits and by Filipin III and Nile Red staining. RESULTS There was an increase in membrane-bound and intracellular cholesterol in the cortex of mice treated with AOM that was associated with decreased Cyp46A1 expression. Strategies to inhibit FXR signaling prevented the down-regulation of Cyp46A1 and the accumulation of cholesterol. Treatment of mice with 2-hydroxypropyl-β-cyclodextrin attenuated the AOM-induced cholesterol accumulation in the brain and the cognitive and neuromuscular deficits without altering the underlying liver pathology. CONCLUSIONS During hepatic encephalopathy, FXR signaling increases brain cholesterol and contributes to neurologic decline. Targeting cholesterol accumulation in the brain may be a possible therapeutic target for the management of hepatic encephalopathy.
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Key Words
- 2-HβC, 2-hypdroxypropyl-β-cyclodextrin
- AOM, azoxymethane
- Acute Liver Failure
- Azoxymethane
- CYP46A1, cytochrome p450 46A1
- CYP7A1, cytochrome p450 7A1
- Cytochrome p450 46A1
- FXR, farnesoid X receptor
- Farnesoid X Receptor
- GAPDH, glyceraldehyde-3-phosphate dehydrogenase
- PBS, phosphate-buffered saline
- PFA, paraformaldehyde
- RT-PCR, reverse-transcription polymerase chain reaction
- WT, wild-type
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Affiliation(s)
- Matthew McMillin
- Central Texas Veterans Healthcare System, Temple, Texas,Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Stephanie Grant
- Central Texas Veterans Healthcare System, Temple, Texas,Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Gabriel Frampton
- Central Texas Veterans Healthcare System, Temple, Texas,Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Anca D. Petrescu
- Central Texas Veterans Healthcare System, Temple, Texas,Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Jessica Kain
- Central Texas Veterans Healthcare System, Temple, Texas,Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Elaina Williams
- Central Texas Veterans Healthcare System, Temple, Texas,Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Rebecca Haines
- Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Lauren Canady
- Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas
| | - Sharon DeMorrow
- Central Texas Veterans Healthcare System, Temple, Texas,Department of Medical Physiology, Texas A&M College of Medicine, Temple, Texas,Correspondence Address correspondence to: Sharon DeMorrow, PhD, Department of Medical Physiology, Texas A&M Health Science Center, Central Texas Veterans Health Care System, Building 205, 1901 South 1st Street, Temple, Texas 76504. fax: (254) 743-0378.
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25
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Karvellas CJ, Speiser JL, Tremblay M, Lee WM, Rose CF. The association between FABP7 serum levels with survival and neurological complications in acetaminophen-induced acute liver failure: a nested case-control study. Ann Intensive Care 2017; 7:99. [PMID: 28983815 PMCID: PMC5629189 DOI: 10.1186/s13613-017-0323-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2017] [Accepted: 09/19/2017] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Acetaminophen (APAP)-induced acute liver failure (ALF) is associated with significant mortality due to intracranial hypertension (ICH), a result of cerebral edema (CE) and astrocyte swelling. Brain-type fatty acid-binding protein (FABP7) is a small (15 kDa) cytoplasmic protein abundantly expressed in astrocytes. The aim of this study was to determine whether serum FABP7 levels early (day 1) or late (days 3-5) level were associated with 21-day mortality and/or the presence of ICH/CE in APAP-ALF patients. METHODS Serum samples from 198 APAP-ALF patients (nested case-control study with 99 survivors and 99 non-survivors) were analyzed by ELISA methods and assessed with clinical data from the US Acute Liver Failure Study Group (ALFSG) Registry (1998-2014). RESULTS APAP-ALF survivors had significantly lower serum FABP7 levels on admission (147.9 vs. 316.5 ng/ml, p = 0.0002) and late (87.3 vs. 286.2 ng/ml, p < 0.0001) compared with non-survivors. However, a significant association between 21-day mortality and increased serum FABP7 early [log FABP7 odds ratio (OR) 1.16, p = 0.32] and late (log FABP7 ~ OR 1.34, p = 0.21) was not detected after adjusting for significant covariates (MELD, vasopressor use). Areas under the receiver-operating curve for early and late multivariable models were 0.760 and 0.892, respectively. In a second analysis, patients were grouped based on the presence (n = 46) or absence (n = 104) of ICH/CE. A significant difference in FABP7 levels between patients with or without ICH/CE at early (259.7 vs. 228.2 ng/ml, p = 0.61) and late (223.8 vs. 192.0 ng/ml, p = 0.19) time points was not identified. CONCLUSION Serum FABP7 levels were significantly elevated at early and late time points in APAP-ALF non-survivors compared to survivors. However, significant differences in FABP7 levels by 21-day mortality were not ascertained after adjusting for significant covariates (reflecting severity of illness). Our study suggests that FABP7 may not discriminate between patients with or without intracranial complications.
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Affiliation(s)
- Constantine J Karvellas
- Division of Gastroenterology (Liver Unit), Department of Critical Care Medicine, University of Alberta, 1-40 Zeidler Ledcor Building, Edmonton, AB, T6G-2X8, Canada.
| | - Jaime L Speiser
- Department of Public Health Sciences, Medical University of South Carolina, Charleston, SC, USA
| | - Mélanie Tremblay
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montreal, Canada
| | - William M Lee
- Division of Digestive and Liver Diseases, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Christopher F Rose
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montreal, Canada
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26
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Liu XM, Peyton KJ, Durante W. Ammonia promotes endothelial cell survival via the heme oxygenase-1-mediated release of carbon monoxide. Free Radic Biol Med 2017; 102:37-46. [PMID: 27867098 PMCID: PMC5209302 DOI: 10.1016/j.freeradbiomed.2016.11.029] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 11/03/2016] [Accepted: 11/16/2016] [Indexed: 01/07/2023]
Abstract
Although endothelial cells produce substantial quantities of ammonia during cell metabolism, the physiologic role of this gas in these cells is not known. In this study, we investigated if ammonia regulates the expression of heme oxygenase-1 (HO-1), and if this enzyme influences the biological actions of ammonia on endothelial cells. Exogenously administered ammonia, given as ammonium chloride or ammonium hydroxide, or endogenously generated ammonia stimulated HO-1 protein expression in cultured human and murine endothelial cells. Dietary supplementation of ammonia also induced HO-1 protein expression in murine arteries. The increase in HO-1 protein by ammonia in endothelial cells was first detected 4h after ammonia exposure and was associated with the induction of HO-1 mRNA, enhanced production of reactive oxygen species (ROS), and increased expression and activity of NF-E2-related factor-2 (Nrf2). Ammonia also activated the HO-1 promoter and this was blocked by mutating the antioxidant responsive element or by overexpressing dominant-negative Nrf2. The induction of HO-1 expression by ammonia was dependent on ROS formation and prevented by N-acetylcysteine or rotenone. Finally, prior treatment of endothelial cells with ammonia inhibited tumor necrosis factor-α-stimulated cell death. However, silencing HO-1 expression abrogated the protective action of ammonia and this was reversed by the administration of carbon monoxide but not bilirubin or iron. In conclusion, this study demonstrates that ammonia stimulates the expression of HO-1 in endothelial cells via the ROS-Nrf2 pathway, and that the induction of HO-1 contributes to the cytoprotective action of ammonia by generating carbon monoxide. Moreover, it identifies ammonia as a potentially important signaling gas in the vasculature that promotes endothelial cell survival.
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Affiliation(s)
- Xiao-Ming Liu
- Department of Medical Pharmacology and Physiology, School of Medicine, University of Missouri-Columbia, M409 Medical Sciences Building, One Hospital Drive, Columbia, MO 65212, USA
| | - Kelly J Peyton
- Department of Medical Pharmacology and Physiology, School of Medicine, University of Missouri-Columbia, M409 Medical Sciences Building, One Hospital Drive, Columbia, MO 65212, USA
| | - William Durante
- Department of Medical Pharmacology and Physiology, School of Medicine, University of Missouri-Columbia, M409 Medical Sciences Building, One Hospital Drive, Columbia, MO 65212, USA.
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27
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Palenzuela L, Oria M, Romero-Giménez J, Garcia-Lezana T, Chavarria L, Cordoba J. Gene expression profiling of brain cortex microvessels may support brain vasodilation in acute liver failure rat models. Metab Brain Dis 2016; 31:1405-1417. [PMID: 27406245 DOI: 10.1007/s11011-016-9863-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 06/19/2016] [Indexed: 12/13/2022]
Abstract
Development of brain edema in acute liver failure can increase intracranial pressure, which is a severe complication of the disease. However, brain edema is neither entirely cytotoxic nor vasogenic and the specific action of the brain microvasculature is still unknown. We aimed to analyze gene expression of brain cortex microvessels in two rat models of acute liver failure. In order to identify global gene expression changes we performed a broad transcriptomic approach in isolated brain cortex microvessels from portacaval shunted rats after hepatic artery ligation (HAL), hepatectomy (HEP), or sham by array hybridization and confirmed changes in selected genes by RT-PCR. We found 157 and 270 up-regulated genes and 143 and 149 down-regulated genes in HAL and HEP rats respectively. Western blot and immunohistochemical assays were performed in cortex and ELISA assays to quantify prostaglandin E metabolites were performed in blood of the sagittal superior sinus. We Identified clusters of differentially expressed genes involving inflammatory response, transporters-channels, and homeostasis. Up-regulated genes at the transcriptional level were associated with vasodilation (prostaglandin-E synthetase, prostaglandin-E receptor, adrenomedullin, bradykinin receptor, adenosine transporter), oxidative stress (hemoxygenase, superoxide dismutase), energy metabolism (lactate transporter) and inflammation (haptoglobin). The only down-regulated tight junction protein was occludin but slightly. Prostaglandins levels were increased in cerebral blood with progression of liver failure. In conclusion, in acute liver failure, up-regulation of several genes at the level of microvessels might suggest an involvement of energy metabolism accompanied by cerebral vasodilation in the cerebral edema at early stages.
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Affiliation(s)
- Lluis Palenzuela
- Servei de Medicina Interna-Hepatologia, Valld'Hebron Institut de Recerca (VH-IR), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain
- Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Marc Oria
- Servei de Medicina Interna-Hepatologia, Valld'Hebron Institut de Recerca (VH-IR), Barcelona, Spain.
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain.
- Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain.
- Center for Fetal, Cellular and Mollecular Therapy, Division of Pediatric General and Thoracic Surgery, Cincinnati Children's Hospital Medical Center (CCHMC), Cincinnati, OH, USA.
| | - Jordi Romero-Giménez
- Servei de Medicina Interna-Hepatologia, Valld'Hebron Institut de Recerca (VH-IR), Barcelona, Spain
- Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Teresa Garcia-Lezana
- Servei de Medicina Interna-Hepatologia, Valld'Hebron Institut de Recerca (VH-IR), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain
- Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Laia Chavarria
- Servei de Medicina Interna-Hepatologia, Valld'Hebron Institut de Recerca (VH-IR), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain
- Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Juan Cordoba
- Servei de Medicina Interna-Hepatologia, Valld'Hebron Institut de Recerca (VH-IR), Barcelona, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain
- Departament de Medicina, Universitat Autònoma de Barcelona, Barcelona, Spain
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28
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Liu TH, Liu DH, Mo CJ, Sun L, Liu XX, Li W, Zhang S, Liu YK, Guo K. Glycosylation patterns and PHA-E-associated glycoprotein profiling associated with early hepatic encephalopathy in Chinese hepatocellular carcinoma patients. Am J Transl Res 2016; 8:4250-4264. [PMID: 27830009 PMCID: PMC5095318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 10/02/2016] [Indexed: 06/06/2023]
Abstract
Hepatic encephalopathy (HE) as a severe neuropsychiatric complication is commonly present in the end stage of Hepatocellular Carcinoma (HCC). However, widely accepted biomarkers for diagnosing early HE are still absent. Here, we screened glycosylation patterns of serum proteins from Chinese HCC patients with or without early HE by lectin microarray. Then, phaseolus vulgaris erythroagglutinin (PHA-E) as a lectin binding with bisecting GlcNAc structure which was significantly decreased in sera from Chinese HCC patients with early HE, was chosen to perform lectin affinity chromatography, following by in-gel digestion, Mass Spectrometry (MS) analysis and bioinformatics analysis. Here we found, 13 lectins showed statistically significant reduction suggesting GalNAc, terminal α-1,3 Man, bisecting GlcNAc, (GlcNAc)n, O-GlcNAc, Neu5Ac, tetra-antennary complex-type N-glycan and GalNAc α/β1-3/6 Gal were decreased in serum glycoproteins from Chinese HCC patients with early HE. Furthermore, a total of 141 PHA-E-associated glycoproteins were identified in MS, of which 12 serum glycoproteins only in Chinese HCC patients without early HE and 26 serum glycoproteins only in Chinese HCC patients with early HE. In addition, bioinformatics analysis revealed the PHA-E-associated serum glycoproteins only in Chinese HCC patients with early HE might be related to early HE occurrence through p38 MAPK signaling pathway and MAPK/ERK signaling pathway. Collectively, this was the first glycomics study of serum proteins in HCC patients with early HE and it could provide a database for discovering and developing serum biomarkers to identify and predict early HE in HCC patients.
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Affiliation(s)
- Tian-Hua Liu
- Liver Cancer Institute, Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of EducationShanghai, China
- Cancer Research Center, Institutes of Biomedical Sciences, Fudan UniversityShanghai, China
| | - Deng-He Liu
- Department of Clinical Laboratory, First Affiliated Hospital of Guangxi Medical UniversityNanning, Guangxi, China
| | - Cui-Ju Mo
- Department of Clinical Laboratory, First Affiliated Hospital of Guangxi Medical UniversityNanning, Guangxi, China
| | - Lu Sun
- Cancer Research Center, Institutes of Biomedical Sciences, Fudan UniversityShanghai, China
| | - Xiao-Xia Liu
- Department of Obstetrics and Gynecology, Obstetrics and Gynecology Hospital of Fudan UniversityShanghai 200032, China
| | - Wei Li
- Cancer Research Center, Institutes of Biomedical Sciences, Fudan UniversityShanghai, China
| | - Shu Zhang
- Liver Cancer Institute, Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of EducationShanghai, China
| | - Yin-Kun Liu
- Liver Cancer Institute, Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of EducationShanghai, China
- Cancer Research Center, Institutes of Biomedical Sciences, Fudan UniversityShanghai, China
| | - Kun Guo
- Liver Cancer Institute, Zhongshan Hospital, Fudan University, Key Laboratory of Carcinogenesis and Cancer Invasion, Ministry of EducationShanghai, China
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L’encéphalopathie hépatique, du diagnostic au traitement en 2016. MEDECINE INTENSIVE REANIMATION 2016. [DOI: 10.1007/s13546-016-1223-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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30
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Bile Acid Signaling Is Involved in the Neurological Decline in a Murine Model of Acute Liver Failure. THE AMERICAN JOURNAL OF PATHOLOGY 2015; 186:312-23. [PMID: 26683664 DOI: 10.1016/j.ajpath.2015.10.005] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 10/06/2015] [Accepted: 10/09/2015] [Indexed: 12/13/2022]
Abstract
Hepatic encephalopathy is a serious neurological complication of liver failure. Serum bile acids are elevated after liver damage and may disrupt the blood-brain barrier and enter the brain. Our aim was to assess the role of serum bile acids in the neurological complications after acute liver failure. C57Bl/6 or cytochrome p450 7A1 knockout (Cyp7A1(-/-)) mice were fed a control, cholestyramine-containing, or bile acid-containing diet before azoxymethane (AOM)-induced acute liver failure. In parallel, mice were given an intracerebroventricular infusion of farnesoid X receptor (FXR) Vivo-morpholino before AOM injection. Liver damage, neurological decline, and molecular analyses of bile acid signaling were performed. Total bile acid levels were increased in the cortex of AOM-treated mice. Reducing serum bile acids via cholestyramine feeding or using Cyp7A1(-/-) mice reduced bile acid levels and delayed AOM-induced neurological decline, whereas cholic acid or deoxycholic acid feeding worsened AOM-induced neurological decline. The expression of bile acid signaling machinery apical sodium-dependent bile acid transporter, FXR, and small heterodimer partner increased in the frontal cortex, and blocking FXR signaling delayed AOM-induced neurological decline. In conclusion, circulating bile acids may play a pathological role during hepatic encephalopathy, although precisely how they dysregulate normal brain function is unknown. Strategies to minimize serum bile acid concentrations may reduce the severity of neurological complications associated with liver failure.
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TGFβ1 exacerbates blood-brain barrier permeability in a mouse model of hepatic encephalopathy via upregulation of MMP9 and downregulation of claudin-5. J Transl Med 2015; 95:903-13. [PMID: 26006017 PMCID: PMC5040071 DOI: 10.1038/labinvest.2015.70] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Revised: 04/09/2015] [Accepted: 04/26/2015] [Indexed: 02/07/2023] Open
Abstract
Recent studies have found that vasogenic brain edema is present during hepatic encephalopathy following acute liver failure and is dependent on increased matrix metalloproteinase 9 (MMP9) activity and downregulation of tight junction proteins. Furthermore, circulating transforming growth factor β1 (TGFβ1) is increased following liver damage and may promote endothelial cell permeability. This study aimed to assess whether increased circulating TGFβ1 drives changes in tight junction protein expression and MMP9 activity following acute liver failure. Blood-brain barrier permeability was assessed in azoxymethane (AOM)-treated mice at 6, 12, and 18 h post-injection via Evan's blue extravasation. Monolayers of immortalized mouse brain endothelial cells (bEnd.3) were treated with recombinant TGFβ1 (rTGFβ1) and permeability to fluorescein isothiocyanate-dextran (FITC-dextran), MMP9 and claudin-5 expression was assessed. Antagonism of TGFβ1 signaling was performed in vivo to determine its role in blood-brain barrier permeability. Blood-brain barrier permeability was increased in mice at 18 h following AOM injection. Treatment of bEnd.3 cells with rTGFβ1 led to a dose-dependent increase of MMP9 expression as well as a suppression of claudin-5 expression. These effects of rTGFβ1 on MMP9 and claudin-5 expression could be reversed following treatment with a SMAD3 inhibitor. AOM-treated mice injected with neutralizing antibodies against TGFβ demonstrated significantly reduced blood-brain barrier permeability. Blood-brain barrier permeability is induced in AOM mice via a mechanism involving the TGFβ1-driven SMAD3-dependent upregulation of MMP9 expression and decrease of claudin-5 expression. Therefore, treatment modalities aimed at reducing TGFβ1 levels or SMAD3 activity may be beneficial in promoting blood-brain barrier integrity following liver failure.
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Jayakumar AR, Rama Rao KV, Norenberg MD. Neuroinflammation in hepatic encephalopathy: mechanistic aspects. J Clin Exp Hepatol 2015; 5:S21-8. [PMID: 26041953 PMCID: PMC4442850 DOI: 10.1016/j.jceh.2014.07.006] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Accepted: 07/08/2014] [Indexed: 12/12/2022] Open
Abstract
Hepatic encephalopathy (HE) is a major neurological complication of severe liver disease that presents in acute and chronic forms. While elevated brain ammonia level is known to be a major etiological factor in this disorder, recent studies have shown a significant role of neuroinflammation in the pathogenesis of both acute and chronic HE. This review summarizes the involvement of ammonia in the activation of microglia, as well as the means by which ammonia triggers inflammatory responses in these cells. Additionally, the role of ammonia in stimulating inflammatory events in brain endothelial cells (ECs), likely through the activation of the toll-like receptor-4 and the associated production of cytokines, as well as the stimulation of various inflammatory factors in ECs and in astrocytes, are discussed. This review also summarizes the inflammatory mechanisms by which activation of ECs and microglia impact on astrocytes leading to their dysfunction, ultimately contributing to astrocyte swelling/brain edema in acute HE. The role of microglial activation and its contribution to the progression of neurobehavioral abnormalities in chronic HE are also briefly presented. We posit that a better understanding of the inflammatory events associated with acute and chronic HE will uncover novel therapeutic targets useful in the treatment of patients afflicted with HE.
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Key Words
- AHE, acute hepatic encephalopathy
- ALF, acute liver failure
- BBB, blood–brain barrier
- BDL, bile duct ligation
- COX2, cyclooxygenase-2
- ECs, endothelial cells
- FHF, fulminant hepatic failure
- HE, hepatic encephalopathy
- HO, hemoxygenase
- IL, interleukin
- LPS, lipopolysaccharide
- MAPK, mitogen-activated protein kinases
- NF-κB, nuclear factor-kappaB
- NOX, NADPH oxidase
- ONS, oxidative/nitrative stress
- PLA2, phospholipase-A2
- RONS, reactive oxygen and nitrogen species
- TLR, Toll-like receptor
- TNF-α, tumor necrosis factor-alpha
- Tg, transgenic
- WT, wild type
- ammonia
- cNOS, constitutive nitric oxide synthase
- hepatic encephalopathy
- iNOS, inducible nitric oxide synthase
- neuroinflammation
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Affiliation(s)
| | | | - Michael D. Norenberg
- Laboratory of Neuropathology, Veterans Affairs Medical Center, Miami, FL, USA,Department of Pathology, University of Miami School of Medicine, Miami, FL, USA,Biochemistry & Molecular Biology, University of Miami School of Medicine, Miami, FL, USA,Address for correspondence: Michael D. Norenberg, Department of Pathology (D-33), PO Box 016960, University of Miami School of Medicine, Miami, FL 33101. Tel.: +1 305 575 7000x4018.
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33
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Duarte S, Baber J, Fujii T, Coito AJ. Matrix metalloproteinases in liver injury, repair and fibrosis. Matrix Biol 2015; 44-46:147-56. [PMID: 25599939 PMCID: PMC4495728 DOI: 10.1016/j.matbio.2015.01.004] [Citation(s) in RCA: 315] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2014] [Revised: 01/09/2015] [Accepted: 01/10/2015] [Indexed: 01/18/2023]
Abstract
The liver is a large highly vascularized organ with a central function in metabolic homeostasis, detoxification, and immunity. Due to its roles, the liver is frequently exposed to various insults which can cause cell death and hepatic dysfunction. Alternatively, the liver has a remarkable ability to self-repair and regenerate after injury. Liver injury and regeneration have both been linked to complex extracellular matrix (ECM) related pathways. While normal degradation of ECM components is an important feature of tissue repair and remodeling, irregular ECM turnover contributes to a variety of liver diseases. Matrix metalloproteinases (MMPs) are the main enzymes implicated in ECM degradation. MMPs not only remodel the ECM, but also regulate immune responses. In this review, we highlight some of the MMP-attributed roles in acute and chronic liver injury and emphasize the need for further experimentation to better understand their functions during hepatic physiological conditions and disease progression.
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Affiliation(s)
- Sergio Duarte
- The Dumont-UCLA Transplant Center, Division of Liver and Pancreas Transplantation, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - John Baber
- The Dumont-UCLA Transplant Center, Division of Liver and Pancreas Transplantation, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Takehiro Fujii
- The Dumont-UCLA Transplant Center, Division of Liver and Pancreas Transplantation, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Ana J Coito
- The Dumont-UCLA Transplant Center, Division of Liver and Pancreas Transplantation, Department of Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States.
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Rama Rao KV, Jayakumar AR, Norenberg MD. Brain edema in acute liver failure: mechanisms and concepts. Metab Brain Dis 2014; 29:927-36. [PMID: 24567229 DOI: 10.1007/s11011-014-9502-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Accepted: 02/05/2014] [Indexed: 12/18/2022]
Abstract
Brain edema and associated increase in intracranial pressure continue to be lethal complications of acute liver failure (ALF). Abundant evidence suggests that the edema in ALF is largely cytotoxic brought about by swelling of astrocytes. Elevated blood and brain ammonia levels have been strongly implicated in the development of the brain edema. Additionally, inflammation and sepsis have been shown to contribute to the astrocyte swelling/brain edema in the setting of ALF. We posit that ammonia initiates a number of signaling events, including oxidative/nitrative stress (ONS), the mitochondrial permeability transition (mPT), activation of the transcription factor (NF-κB) and signaling kinases, all of which have been shown to contribute to the mechanism of astrocyte swelling. All of these factors also impact ion-transporters, including Na(+), K(+), Cl(-) cotransporter and the sulfonylurea receptor 1, as well as the water channel protein aquaporin-4 resulting in a perturbation of cellular ion and water homeostasis, ultimately resulting in astrocyte swelling/brain edema. All of these events are also potentiated by inflammation. This article reviews contemporary knowledge regarding mechanisms of astrocyte swelling/brain edema formation which hopefully will facilitate the identification of therapeutic targets capable of mitigating the brain edema associated with ALF.
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Affiliation(s)
- Kakulavarapu V Rama Rao
- Department of Pathology, University of Miami Miller School of Medicine, PO Box 016960, Miami, FL, 33101, USA,
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McMillin M, Frampton G, Thompson M, Galindo C, Standeford H, Whittington E, Alpini G, DeMorrow S. Neuronal CCL2 is upregulated during hepatic encephalopathy and contributes to microglia activation and neurological decline. J Neuroinflammation 2014; 11:121. [PMID: 25012628 PMCID: PMC4128607 DOI: 10.1186/1742-2094-11-121] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 06/30/2014] [Indexed: 12/31/2022] Open
Abstract
Background Acute liver failure leads to systemic complications with one of the most dangerous being a decline in neurological function, termed hepatic encephalopathy. Neurological dysfunction is exacerbated by an increase of toxic metabolites in the brain that lead to neuroinflammation. Following various liver diseases, hepatic and circulating chemokines, such as chemokine ligand 2 (CCL2), are elevated, though their effects on the brain following acute liver injury and subsequent hepatic encephalopathy are unknown. CCL2 is known to activate microglia in other neuropathies, leading to a proinflammatory response. However, the effects of CCL2 on microglia activation and the pathogenesis of hepatic encephalopathy following acute liver injury remain to be determined. Methods Hepatic encephalopathy was induced in mice via injection of azoxymethane (AOM) in the presence or absence of INCB 3284 dimesylate (INCB), a chemokine receptor 2 inhibitor, or C 021 dihydrochloride (C021), a chemokine receptor 4 inhibitor. Mice were monitored for neurological decline and time to coma (loss of all reflexes) was recorded. Tissue was collected at coma and used for real-time PCR, immunoblots, ELISA, or immunostaining analyses to assess the activation of microglia and consequences on pro-inflammatory cytokine expression. Results Following AOM administration, microglia activation was significantly increased in AOM-treated mice compared to controls. Concentrations of CCL2 in the liver, serum, and cortex were significantly elevated in AOM-treated mice compared to controls. Systemic administration of INCB or C021 reduced liver damage as assessed by serum liver enzyme biochemistry. Administration of INCB or C021 significantly improved the neurological outcomes of AOM-treated mice, reduced microglia activation, reduced phosphorylation of ERK1/2, and alleviated AOM-induced cytokine upregulation. Conclusions These findings suggest that CCL2 is elevated systemically following acute liver injury and that CCL2 is involved in both the microglia activation and neurological decline associated with hepatic encephalopathy. Methods used to modulate CCL2 levels and/or reduce CCR2/CCR4 activity may be potential therapeutic targets for the management of hepatic encephalopathy due to acute liver injury.
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Affiliation(s)
| | | | | | | | | | | | | | - Sharon DeMorrow
- Department of Internal Medicine, Texas A&M Health Science Center, College of Medicine, 1901 South 1st Street, Building 205, Temple, Texas, USA.
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Wang JB, Wang DL, Wang HT, Wang ZH, Wen Y, Sun CM, Zhao YT, Wu J, Liu P. Tumor necrosis factor-alpha-induced reduction of glomerular filtration rate in rats with fulminant hepatic failure. J Transl Med 2014; 94:740-51. [PMID: 24887412 DOI: 10.1038/labinvest.2014.71] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2013] [Revised: 04/11/2014] [Accepted: 04/20/2014] [Indexed: 12/16/2022] Open
Abstract
The mechanism of renal failure during fulminant hepatic failure (FHF) or end-stage of liver disease is not fully understood. The present study aims to delineate the mechanisms of decreased glomerular filtration rate (GFR) in acute hepatic failure. A rat model of renal insufficiency in severe liver injury was established by lipopolysaccharide (LPS) plus D-galactosamine (GalN) exposure. GFR was evaluated by continuous infusion of fluorescein isothiocyanate-inulin with implanted micro-osmotic pumps. GalN/LPS intoxication resulted in severe hepatocyte toxicity as evidenced by liver histology and biochemical tests, whereas renal morphology remained normal. GFR was reduced by 33% of the controls 12 h after GalN/LPS exposure, accompanied with a decreased serum sodium levels, a marked increase in serum TNF-α and ET-1 levels as well as significantly upregulated renal type 1 inositol 1,4,5-trisphosphate receptor (IP3R1) expression. The upregulated IP3R1 expression was abrogated by the treatment of anti-TNF-α antibodies, but not by 2-aminoethoxydiphenylborate (2-APB), which blocks the inositol 1,4,5-trisphosphate signaling pathway. Treatments with either TNF-α antibodies or 2-APB also significantly improved the compromised GFR, elevated serum urea nitrogen and creatinine levels, and reversed the decrease in glomerular inulin space and the increase in glomerular calcium content in GalN/LPS-exposed rats. The extent of acute liver injury as reflected by serum ALT levels was much more attenuated by anti-TNF-α antibodies than by 2-APB. Liver histology further confirmed that anti-TNF-α antibodies conferred better protection than 2-APB in GalN/LPS-exposed rats. LPS-elicited TNF-α over-production is responsible for decreased GFR through IP3R1 overexpression, and the compromised GFR resulted in the development of acute renal failure in rats with FHF.
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Affiliation(s)
- Jing-Bo Wang
- 1] Department of Infectious Diseases, The First Affiliated Hospital, China Medical University, Shenyang City, People's Republic of China [2] Division of Gastroenterology, Department of Internal Medicine, The Sixth People's Hospital of Shenyang, Shenyang City, People's Republic of China
| | - Dong-Lei Wang
- Department of Infectious Diseases, The First Affiliated Hospital, China Medical University, Shenyang City, People's Republic of China
| | - Hai-Tao Wang
- Division of Hepatobiliary Diseases, Department of Surgery, The Affiliated Shenzhou Hospital of Shenyang Medical College, Shenyang City, People's Republic of China
| | - Zhao-Han Wang
- Department of Infectious Diseases, The First Affiliated Hospital, China Medical University, Shenyang City, People's Republic of China
| | - Ying Wen
- Department of Infectious Diseases, The First Affiliated Hospital, China Medical University, Shenyang City, People's Republic of China
| | - Cui-Ming Sun
- Department of Infectious Diseases, The First Affiliated Hospital, China Medical University, Shenyang City, People's Republic of China
| | - Yi-Tong Zhao
- Division of Gastroenterology, Department of Internal Medicine, The Sixth People's Hospital of Shenyang, Shenyang City, People's Republic of China
| | - Jian Wu
- 1] Department of Internal Medicine, Division of Gastroenterology and Hepatology, University of California, Davis Medical Center, Sacramento, CA, USA [2] Key Laboratory of Molecular Virology, Fudan University College of Basic Medical Sciences, Shanghai, People's Republic of China
| | - Pei Liu
- Department of Infectious Diseases, The First Affiliated Hospital, China Medical University, Shenyang City, People's Republic of China
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Hori T, Uemoto S, Walden LB, Chen F, Baine AMT, Hata T, Kogure T, Nguyen JH. Matrix metalloproteinase-9 as a therapeutic target for the progression of fulminant liver failure with hepatic encephalopathy: A pilot study in mice. Hepatol Res 2014; 44:651-62. [PMID: 23672352 DOI: 10.1111/hepr.12161] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 05/08/2013] [Accepted: 05/09/2013] [Indexed: 12/13/2022]
Abstract
AIM If progressive liver injury and subsequent hepatic encephalopathy can be prohibited in fulminant liver failure (FLF), it would be ideal for intensive care of FLF and provide an expanded opportunity for liver transplantation (LT). We hypothesized that matrix metalloproteinase (MMP)-9 plays an important role in FLF progression, and investigated MMP-9 behaviors in a murine FLF model, especially at the coma stage. METHODS The murine FLF model with azoxymethane recapitulates FLF in humans. The detailed coma status was evaluated, on the assumption that LT is indicated at early, but not late, stage 3. To investigate whether MMP-9 deletion or reduction has beneficial effects, an MMP-9 inhibitor (GM6001) and transfection of tissue inhibitor of metalloproteinases (TIMP)-1 cDNA were used. Mice were divided into five groups: control; FLF; FLF with GM6001 pretreatment; FLF with TIMP-1 plasmid transfection 24 h before disease onset; and FLF with TIMP-1 plasmid transfection 48 h before disease onset. Neurological findings, including survival, were followed. Samples were obtained at early and late stage 3. Biochemical examinations and histopathological assessments were performed. The expression and function of MMP-9 and TIMP-1 were evaluated by western blotting and zymography. A brain permeability study was also performed. RESULTS MMP-9 was strongly increased in FLF. The MMP-9 inhibitions worked well, and prolonged the survival, interval to stage 3 and duration of early stage 3. MMP-9 inhibition improved the liver and subsequent brain injuries at early stage 3, with no remarkable improvements at late stage 3. CONCLUSION MMP-9 has therapeutic potential for FLF progression.
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Affiliation(s)
- Tomohide Hori
- Department of Neuroscience, Mayo Clinic in Florida; Division of Hepato-Biliary-Pancreatic and Transplant Surgery, Department of Surgery, Kyoto University Graduate School of Medicine, Kyoto
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Chastre A, Bélanger M, Nguyen BN, Butterworth RF. Lipopolysaccharide precipitates hepatic encephalopathy and increases blood-brain barrier permeability in mice with acute liver failure. Liver Int 2014; 34:353-61. [PMID: 23910048 DOI: 10.1111/liv.12252] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/03/2013] [Revised: 05/16/2013] [Accepted: 05/31/2013] [Indexed: 12/25/2022]
Abstract
BACKGROUND & AIMS Acute liver failure (ALF) is frequently complicated by infection leading to precipitation of central nervous system complications such as hepatic encephalopathy (HE) and increased mortality. There is evidence to suggest that when infection occurs in ALF patients, the resulting pro-inflammatory mechanisms may be amplified that could, in turn, have a major impact on blood-brain barrier (BBB) function. The aim of this study was to investigate the role of endotoxemia on the progression of encephalopathy in relation to BBB permeability during ALF. METHODS Adult male C57-BL6 mice with ALF resulting from azoxymethane-induced toxic liver injury were administered trace amounts of the endotoxin component lipopolysaccharide (LPS). Effects on the magnitude of the systemic inflammatory response, liver pathology and BBB integrity were measured as a function of progression of HE, defined as time to loss of corneal reflex (coma). RESULTS Lipopolysaccharide caused additional two- to seven-fold (P < 0.001) increases in circulating pro-inflammatory cytokines (TNF-α, IL-1β, IL-6), worsening liver pathology and associated increases of circulating transaminases as well as increased hyperammonaemia consistent with a further loss of viable hepatocytes. LPS treatment of ALF mice led to a rapid precipitation of hepatic coma and the BBB became permeable to the 25-kDa protein immunoglobulin G (IgG). This extravasation of IgG was accompanied by ignificant up-regulation of matrix metalloproteinase-9 (MMP-9), an endopeptidase known to modulate opening of the BBB in a wide range of neurological disorders. CONCLUSIONS These findings represent the first direct evidence of inflammation-related BBB permeability changes in ALF.
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Affiliation(s)
- Anne Chastre
- Neuroscience Research Unit, Saint-Luc Hospital, CRCHUM, Montreal, QC, Canada
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Scott TR, Kronsten VT, Hughes RD, Shawcross DL. Pathophysiology of cerebral oedema in acute liver failure. World J Gastroenterol 2013; 19:9240-9255. [PMID: 24409052 PMCID: PMC3882398 DOI: 10.3748/wjg.v19.i48.9240] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 10/28/2013] [Accepted: 11/19/2013] [Indexed: 02/06/2023] Open
Abstract
Cerebral oedema is a devastating consequence of acute liver failure (ALF) and may be associated with the development of intracranial hypertension and death. In ALF, some patients may develop cerebral oedema and increased intracranial pressure but progression to life-threatening intracranial hypertension is less frequent than previously described, complicating less than one third of cases who have proceeded to coma since the advent of improved clinical care. The rapid onset of encephalopathy may be dramatic with the development of asterixis, delirium, seizures and coma. Cytotoxic and vasogenic oedema mechanisms have been implicated with a preponderance of experimental data favouring a cytotoxic mechanism. Astrocyte swelling is the most consistent neuropathological finding in humans with ALF and ammonia plays a definitive role in the development of cytotoxic brain oedema. The mechanism(s) by which ammonia induces astrocyte swelling remains unclear but glutamine accumulation within astrocytes has led to the osmolyte hypothesis. Current evidence also supports an alternate ‘Trojan horse’ hypothesis, with glutamine as a carrier of ammonia into mitochondria, where its accumulation results in oxidative stress, energy failure and ultimately astrocyte swelling. Although a complete breakdown of the blood-brain barrier is not evident in human ALF, increased permeation to water and other small molecules such as ammonia has been demonstrated resulting from subtle alterations in the protein composition of paracellular tight junctions. At present, there is no fully efficacious therapy for cerebral oedema other than liver transplantation and this reflects our incomplete knowledge of the precise mechanisms underlying this process which remain largely unknown.
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Jayakumar AR, Ruiz-Cordero R, Tong XY, Norenberg MD. Brain edema in acute liver failure: role of neurosteroids. Arch Biochem Biophys 2013; 536:171-5. [PMID: 23567839 PMCID: PMC4737089 DOI: 10.1016/j.abb.2013.03.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2013] [Revised: 03/07/2013] [Accepted: 03/18/2013] [Indexed: 12/12/2022]
Abstract
Brain edema is a major neurological complication of acute liver failure (ALF) and swelling of astrocytes (cytotoxic brain edema) is the most prominent neuropathological abnormality in this condition. Elevated brain ammonia level has been strongly implicated as an important factor in the mechanism of astrocyte swelling/brain edema in ALF. Recent studies, however, have suggested the possibility of a vasogenic component in the mechanism in ALF. We therefore examined the effect of ammonia on blood-brain barrier (BBB) integrity in an in vitro co-culture model of the BBB (consisting of primary cultures of rat brain endothelial cells and astrocytes). We found a minor degree of endothelial permeability to dextran fluorescein (16.2%) when the co-culture BBB model was exposed to a pathophysiological concentration of ammonia (5mM). By contrast, lipopolysaccharide (LPS), a molecule well-known to disrupt the BBB, resulted in an 87% increase in permeability. Since increased neurosteroid biosynthesis has been reported to occur in brain in ALF, and since neurosteroids are known to protect against BBB breakdown, we examined whether neurosteroids exerted any protective effect on the slight permeability of the BBB after exposure to ammonia. We found that a nanomolar concentration (10nM) of the neurosteroids allopregnanolone (THP) and tetrahydrodeoxycorticosterone (THDOC) significantly reduced the ammonia-induced increase in BBB permeability (69.13 and 58.64%, respectively). On the other hand, we found a marked disruption of the BBB when the co-culture model was exposed to the hepatotoxin azoxymethane (218.4%), but not with other liver toxins commonly used as models of ALF (thioacetamide and galactosamine, showed a 29.3 and 30.67% increase in permeability, respectively). Additionally, THP and THDOC reduced the effect of TAA and galactosamine on BBB permeability, while no BBB protective effect was observed following treatment with azoxymethane. These findings suggest that ammonia does not cause a significant BBB disruption, and that the BBB is intact in the TAA or galactosamine-induced animal models of ALF, likely due to the protective effect of neurosteroids that are synthesized in brain in the setting of ALF. However, caution should be exercised when using azoxymethane as an experimental model of ALF as it caused a severe breakdown of the BBB, and neurosteriods failed to protect against this breakdown.
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TIMP-1 attenuates blood-brain barrier permeability in mice with acute liver failure. J Cereb Blood Flow Metab 2013; 33:1041-9. [PMID: 23532086 PMCID: PMC3705430 DOI: 10.1038/jcbfm.2013.45] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 02/28/2013] [Accepted: 03/03/2013] [Indexed: 02/06/2023]
Abstract
Blood-brain barrier (BBB) dysfunction in acute liver failure (ALF) results in increased BBB permeability that often precludes the patients from obtaining a life-saving liver transplantation. It remains controversial whether matrix metalloproteinase-9 (MMP-9) from the injured liver contributes to the deregulation of BBB function in ALF. We selectively upregulated a physiologic inhibitor of MMP-9 (TIMP-1) with a single intracerebroventricular injection of TIMP-1 cDNA plasmids at 48 and 72 hours, or with pegylated-TIMP-1 protein. Acute liver failure was induced with tumor necrosis factor-α and D-(+)-galactosamine in mice. Permeability of BBB was assessed with sodium fluorescein (NaF) extravasation. We found a significant increase in TIMP-1 within the central nervous system (CNS) after the administration of TIMP-1 cDNA plasmids and that increased TIMP-1 within the CNS resulted in an attenuation of BBB permeability, a reduction in activation of epidermal growth factor receptor and p38 mitogen-activated protein kinase signals, and a restoration of the tight junction protein occludin in mice with experimental ALF. Pegylated TIMP-1 provided similar protection against BBB permeability in mice with ALF. Our results provided a proof of principle that MMP-9 contributes to the BBB dysfunction in ALF and suggests a potential therapeutic role of TIMP-1 in ALF.
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Jayakumar AR, Norenberg MD. Endothelial-astrocytic interactions in acute liver failure. Metab Brain Dis 2013; 28:183-6. [PMID: 23099995 DOI: 10.1007/s11011-012-9344-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 10/15/2012] [Indexed: 10/27/2022]
Abstract
Brain edema and the subsequent increase in intracranial pressure are major neurological complications of acute liver failure (ALF), and swelling of astrocytes (cytotoxic brain edema) is the most prominent neuropathological abnormality in ALF. Recent studies, however, have suggested the co-existence of cytotoxic and vasogenic mechanisms in the brain edema associated with ALF. This review 1) summarizes the nature of the brain edema in humans and experimental animals with ALF; 2) reviews in vitro studies supporting the presence of cytotoxic brain edema (cell swelling in cultured astrocytes); and 3) documents the role of brain endothelial cells in the development of astrocyte swelling/brain edema in ALF.
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Alterations of blood-brain barrier and associated factors in acute liver failure. Gastroenterol Res Pract 2013; 2013:841707. [PMID: 23762040 PMCID: PMC3677611 DOI: 10.1155/2013/841707] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 04/08/2013] [Accepted: 05/07/2013] [Indexed: 01/30/2023] Open
Abstract
Brain edema in acute liver failure (ALF) remains lethal. Cytotoxic mechanisms associated with brain edema have been well recognized, but the role of vasogenic mechanisms of brain edema has not been explored. Intact tight junctions (TJs) between brain capillary endothelial cells are critical for normal BBB function. Recent reports found significant alterations in the tight junction elements including occludin and claudin-5, suggesting a vasogenic injury in the blood-brain barrier (BBB) integrity. However, the role of TJ in ALF has not been completely understood. This paper reviews the role of the paracellular tight junction in the increased selective BBB permeability that leads to brain edema in ALF and furthermore explores the effect of systemic inflammatory cytokines on the tight junction dysfunction.
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Ohashi N, Hori T, Uemoto S, Jermanus S, Chen F, Nakao A, Nguyen JH. Hypothermia predicts hepatic failure after extensive hepatectomy in mice. World J Hepatol 2013; 5:170-81. [PMID: 23671721 PMCID: PMC3648648 DOI: 10.4254/wjh.v5.i4.170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2012] [Revised: 11/24/2012] [Accepted: 12/22/2012] [Indexed: 02/06/2023] Open
Abstract
AIM To investigate the effect of hypothermia on the function of the liver remnant (LR) after extended hepatectomy. METHODS We performed a 75% partial hepatectomy (PH) in male C57BL/6J mice. Body temperature was measured with a rectal probe. The study mice were prospectively grouped as hypothermic (HT) or normothermic (NT) if their body temperature was < 34 °C vs ≥ 34 °C, respectively. Blood and liver samples were obtained at 24 and 48 h after 75% PH. Various factors during and after 75% PH were compared at each time point and the most important factor for a good outcome after 75% PH was determined. RESULTS At 24 and 48 h after 75% PH, LR weight was decreased in HT mice compared with that in NT mice and the assay results in the HT mice were consistent with liver failure. NT mice had normal liver regeneration. Each intra- and post-operative factor which showed statistical significance in univariate analysis was evaluated by multivariate analysis. The most important factor for a good outcome after 75% PH was body temperature at both 24 and 48 h after surgery. CONCLUSION Hypothermia after an extensive hepatectomy predicts impending liver failure and may be a useful clinical marker for early detection of liver failure after extended hepatectomy.
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Affiliation(s)
- Norifumi Ohashi
- Norifumi Ohashi, Akimasa Nakao, Gastroenterological Surgery, Nagoya University Graduate School of Medicine, Nagoya, Aichi 466-8550, Japan
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Chavarria L, Alonso J, García-Martínez R, Simón-Talero M, Ventura-Cots M, Ramírez C, Torrens M, Vargas V, Rovira A, Córdoba J. Brain magnetic resonance spectroscopy in episodic hepatic encephalopathy. J Cereb Blood Flow Metab 2013; 33:272-7. [PMID: 23168529 PMCID: PMC3564202 DOI: 10.1038/jcbfm.2012.173] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Brain magnetic resonance (MR) study has shown metabolic abnormalities and changes in water distribution of the brain tissue that may relate to the pathogenesis of hepatic encephalopathy (HE). We designed a study to investigate the disturbances in brain water and metabolites during episodic HE using a 3-T MR scanner. Cirrhotic patients with different grades of HE underwent MR during hospitalization (n=18). The MR was repeated at 6 weeks' follow-up (n=14). The results were compared with those of a group of healthy volunteers (n=8). During episodic HE, brain diffusion-weighted imaging showed a high apparent diffusion coefficient (ADC) (12% to 14%) that decreased during follow-up (-1% to -4%). These disturbances were accompanied by high glutamine (581%), low choline (-31%), and low myo-inositol (-86%) peaks on MR spectroscopy. In overt HE, patients showed high glutamine that decreased during follow-up (-22%). In addition, these patients exhibited a rise in plasma S100 beta and enlargement of brain white-matter lesions. In conclusion, several disturbances detected by MR support the presence of impaired brain water homeostasis during episodic HE. Although astrocytes have a major role in this condition, brain edema during episodic HE may be extracellular and does not appear to be directly responsible for the development of neurologic manifestations.
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Tu Y, Fu J, Wang J, Fu G, Wang L, Zhang Y. Extracellular matrix metalloproteinase inducer is associated with severity of brain oedema following experimental subarachnoid haemorrhage in rats. J Int Med Res 2013; 40:1089-98. [PMID: 22906282 DOI: 10.1177/147323001204000328] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE Brain oedema is a major cause of clinical deterioration and death following brain trauma; cellular mechanisms involved in its development remain elusive. This study investigated the role of extracellular matrix metalloproteinase inducer (EMMPRIN) in brain oedema. METHODS The monofilament puncture model was used to induce subarachnoid haemorrhage. Adult male Sprague-Dawley rats were divided into five groups (n = 20 per group): sham-operated, sacrificed immediately after surgery (sham group); sacrificed 12, 24 or 72 h after subarachnoid haemorrhage induction (SAH-12, SAH-24 and SAH-72 groups, respectively); treated with EMMPRIN inhibitor immediately after subarachnoid haemorrhage, sacrificed at 24 h (SAH-inhibition group). Mean brain water content, and EMMPRIN mRNA and protein levels, were determined. RESULTS Compared with the sham group, mean brain water content, EMMPRIN mRNA and protein levels in the SAH-12, SAH-24 and SAH-72 groups increased rapidly and significantly (maximal at 24 h). EMMPRIN inhibition significantly reduced mean brain water content and EMMPRIN mRNA and protein levels in the SAH-inhibition group, compared with the SAH-24 group. CONCLUSIONS EMMPRIN upregulation may be important in the formation of brain oedema; inhibition of EMMPRIN activity may provide a potential approach to reduce oedema after subarachnoid haemorrhage.
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Affiliation(s)
- Y Tu
- Experimental Surgery Department, Tangdu Hospital, The Fourth Military Medical University, Xi'an, China
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Pathogenesis of hepatic encephalopathy. Gastroenterol Res Pract 2012; 2012:642108. [PMID: 23316223 PMCID: PMC3534214 DOI: 10.1155/2012/642108] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2012] [Revised: 11/16/2012] [Accepted: 11/16/2012] [Indexed: 02/06/2023] Open
Abstract
Hepatic encephalopathy can be a serious complication of acute liver failure and chronic liver diseases, predominantly liver cirrhosis. Hyperammonemia plays the most important role in the pathogenesis of hepatic encephalopathy. The brain-blood barrier disturbances, changes in neurotransmission, neuroinflammation, oxidative stress, GABA-ergic or benzodiazepine pathway abnormalities, manganese neurotoxicity, brain energetic disturbances, and brain blood flow abnormalities are considered to be involved in the development of hepatic encephalopathy. The influence of small intestine bacterial overgrowth (SIBO) on the induction of minimal hepatic encephalopathy is recently emphasized. The aim of this paper is to present the current views on the pathogenesis of hepatic encephalopathy.
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Iwasa M, Mifuji-Moroka R, Kuroda M, Moroka H, Fujita N, Kobayashi Y, Adachi Y, Gabazza EC, Matsuda H, Takei Y. Regional reduction in gray and white matter volume in brains of cirrhotic patients: voxel-based analysis of MRI. Metab Brain Dis 2012; 27:551-7. [PMID: 22618586 DOI: 10.1007/s11011-012-9314-x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Accepted: 05/08/2012] [Indexed: 01/08/2023]
Abstract
Chronic hepatic encephalopathy is a characteristically reversible neuropsychiatric disorder that occurs mainly in patients with liver cirrhosis. The brain regions critically involved in the pathophysiology of cirrhosis are not clear. Magnetic resonance imaging (MRI) with voxel-based morphometry (VBM) is a valuable tool for evaluating structural brain changes in many neurodegenerative diseases. We performed an MRI scan on 18 patients with liver cirrhosis and 16 age-matched healthy controls. We evaluated brain regional structural changes, regional differences and the relationship of these changes with the blood levels of ammonia and the results of neuropsychological tests in patients with cirrhosis. The VBM showed reduction in the volume of gray matter in the cerebellum and occipital lobe and in the volume of white matter in the cingulate, parietal, temporal, occipital lobe and precentral area in cirrhotic patients compared with controls. There were significant correlations between the volume of these regions with the plasma levels of ammonia and the results of neuropsychological tests. Voxel-based analysis of MRI revealed evidence for structural abnormalities of brain in patients with cirrhosis. Abnormal function in the above regions may account for the ammonia-mediated changes and neuropsychological deficits in hepatic encephalopathy.
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Affiliation(s)
- Motoh Iwasa
- Department of Gastroenterology and Hepatology, Mie University Graduate School of Medicine, Edobashi 2-174, Tsu, Mie, 514-8507, Japan.
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Villano G, Lunardi F, Turato C, Schiff S, Tono N, Campagna F, Gatta A, Amodio P, Calabrese F, Pontisso P. Increased Th1 immune response in SERPINB3 transgenic mice during acute liver failure. Exp Biol Med (Maywood) 2012; 237:1474-82. [DOI: 10.1258/ebm.2012.012135] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Acute liver failure (ALF) is characterized by severe neurological complications, known as acute hepatic encephalopathy, where brain ammonia and inflammatory processes play a dominant role. In experimental models of acute liver failure SERPINB3 was found significantly increased in microglia, the intrinsic immune cells of the central nervous system. The aim of the present study was to investigate the extent of brain tissue damage and the inflammatory milieu in experimental acute liver failure using a SERPINB3-transgenic mouse model. C57BL/6J wild-type and transgenic mice were inoculated with acetaminophen or phosphate-buffered saline and sacrificed 20 h postinjection. Proliferation and apoptotic activity were analyzed in brain tissue by immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling technique. The expression of cytokines was analysed in brain and liver tissue by real time polymerase chain reaction and in the corresponding serum samples using a Bio-Plex system. Acetaminophen induced a significantly lower body temperature and shorter survival in transgenic than in wild-type mice, despite liver function was similar in both groups. The brain of transgenic mice, expressing SERPINB3 positivity in microglia, showed increased glial cell number, associated to significant lower apoptotic death events, compared with wild-type mice. In mice injected with acetaminophen, remarkably higher values of cytokines mRNA were observed in the liver of both groups, with a trend toward higher values in transgenic animals. In brain tissue similar increase of tumor necrosis factor-αwas detected in transgenic and wild-type mice, while IL-10 mRNA increased only in the wild-type group. A remarkable increase of circulating Th1 cytokines was detected in serum of transgenic mice, while in the wild-type group they remained rather unchanged. These figures were associated with lower levels of granulocyte macropage colony-stimulating factor, despite similar increase of IL-10 values in both groups. In conclusion, in acute liver failure SERPINB3 determines an enhanced inflammatory background, mainly mediated by higher levels of Th1 proinflammatory cytokines.
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Affiliation(s)
- Gianmarco Villano
- Clinica Medica 5, Department of Medicine, University of Padova, Via Giustiniani, 2 - 35128 Padova
| | - Francesca Lunardi
- Department of Cardiac, Thoracic and Vascular Sciences, University of Padova, Via Gabelli, 61 - 35128 Padova
| | - Cristian Turato
- Istituto Oncologico Veneto IOV-IRCCS, Via Gattamelata, 64-35128 Padova, Italy
| | - Sami Schiff
- Clinica Medica 5, Department of Medicine, University of Padova, Via Giustiniani, 2 - 35128 Padova
| | - Natascia Tono
- Istituto Oncologico Veneto IOV-IRCCS, Via Gattamelata, 64-35128 Padova, Italy
| | - Francesca Campagna
- Clinica Medica 5, Department of Medicine, University of Padova, Via Giustiniani, 2 - 35128 Padova
| | - Angelo Gatta
- Clinica Medica 5, Department of Medicine, University of Padova, Via Giustiniani, 2 - 35128 Padova
| | - Piero Amodio
- Clinica Medica 5, Department of Medicine, University of Padova, Via Giustiniani, 2 - 35128 Padova
| | - Fiorella Calabrese
- Department of Cardiac, Thoracic and Vascular Sciences, University of Padova, Via Gabelli, 61 - 35128 Padova
| | - Patrizia Pontisso
- Clinica Medica 5, Department of Medicine, University of Padova, Via Giustiniani, 2 - 35128 Padova
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Back A, Tupper KY, Bai T, Chiranand P, Goldenberg FD, Frank JI, Brorson JR. Ammonia-induced brain swelling and neurotoxicity in an organotypic slice model. Neurol Res 2012; 33:1100-8. [PMID: 22196764 DOI: 10.1179/1743132811y.0000000046] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVES Acute liver failure (ALF) produces cerebral dysfunction and edema, mediated in part by elevated ammonia concentrations, often leading to coma and death. The pathophysiology of cerebral edema in ALF is incompletely understood. In vitro models of the cerebral effects of ALF have predominately consisted of dissociated astrocyte cultures or acute brain slices. We describe a stable long-term culture model incorporating both neural and glial elements in a three-dimensional tissue structure offering significant advantages to the study of astrocytic-neuronal interactions in the pathophysiology of cerebral edema and dysfunction in ALF. METHODS We utilized chronic organotypic slice cultures from mouse forebrain, applying ammonium acetate in iso-osmolar fashion for 72 hours. Imaging of slice thickness to assess for tissue swelling was accomplished in living slices with optical coherence tomography, and confocal microscopy of fluorescence immunochemical and histochemical staining served to assess astrocyte and neuronal numbers, morphology, and volume in the fixed brain slices. RESULTS Ammonia exposure at 1-10 mM produced swelling of immunochemically identified astrocytes, and at 10 mM resulted in macroscopic tissue swelling, with slice thickness increasing by about 30%. Astrocytes were unchanged in number. In contrast, 10 mM ammonia treatment severely disrupted neuronal morphology and reduced neuronal survival at 72 hours by one-half. DISCUSSION Elevated ammonia produces astrocytic swelling, tissue swelling, and neuronal toxicity in cerebral tissues. Ammonia-treated organotypic brain slice cultures provide an In vitro model of cerebral effects of conditions relevant to ALF, applicable to pathophysiological investigations.
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Affiliation(s)
- Adam Back
- Department of Surgery, The University of Chicago,IL 60637, USA
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