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Bokoch MP, Xu F, Govindaraju K, Lloyd E, Tsutsui K, Kothari RP, Adelmann D, Joffre J, Hellman J. Serum from patients with cirrhosis undergoing liver transplantation induces permeability in human pulmonary microvascular endothelial cells ex vivo. Front Med (Lausanne) 2024; 11:1412891. [PMID: 39021821 PMCID: PMC11252006 DOI: 10.3389/fmed.2024.1412891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Accepted: 06/14/2024] [Indexed: 07/20/2024] Open
Abstract
Introduction Patients with cirrhosis undergoing liver transplantation frequently exhibit systemic inflammation, coagulation derangements, and edema, indicating endothelial dysfunction. This syndrome may worsen after ischemia-reperfusion injury of the liver graft, coincident with organ dysfunction that worsens patient outcomes. Little is known about changes in endothelial permeability during liver transplantation. We hypothesized that sera from these patients would increase permeability in cultured human endothelial cells ex vivo. Methods Adults with cirrhosis presenting for liver transplantation provided consent for blood collection during surgery. Sera were prepared at five time points spanning the entire operation. The barrier function of human pulmonary microvascular endothelial cells in culture was assessed by transendothelial resistance measured using the ECIS ZΘ system. Confluent cells from two different endothelial cell donors were stimulated with human serum from liver transplant patients. Pooled serum from healthy men and purified inflammatory agonists served as controls. The permeability response to serum was quantified as the area under the normalized resistance curve. Responses were compared between time points and analyzed for associations with clinical characteristics of liver transplant patients and their grafts. Results Liver transplant sera from all time points during surgery-induced permeability in both endothelial cell lines. The magnitude of permeability change was heterogeneous between patients, and there were differences in the effects of sera on the two endothelial cell lines. In one of the cell lines, the severity of liver disease was associated with greater permeability at the start of surgery. In the same cell line, serum collected 15 min after liver reperfusion induced significantly more permeability as compared to that collected at the start of surgery. Early postreperfusion sera from patients undergoing living donor transplants induced more permeability than sera from deceased donor transplants. Sera from two exemplary cases of patients on preoperative dialysis, and one patient with an unexpectedly long warm ischemia time of the liver graft, induced exaggerated and prolonged endothelial permeability. Discussion Serum from patients with cirrhosis undergoing liver transplantation induces permeability of cultured human pulmonary microvascular endothelial cells. Increased endothelial permeability during liver transplantation may contribute to organ injury and present a target for future therapeutics.
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Affiliation(s)
- Michael P. Bokoch
- Department of Anesthesia & Perioperative Care, University of California, San Francisco, San Francisco, CA, United States
| | - Fengyun Xu
- Department of Anesthesia & Perioperative Care, University of California, San Francisco, San Francisco, CA, United States
| | - Krishna Govindaraju
- Department of Anesthesia & Perioperative Care, University of California, San Francisco, San Francisco, CA, United States
| | - Elliot Lloyd
- Department of Anesthesia & Perioperative Care, University of California, San Francisco, San Francisco, CA, United States
| | - Kyle Tsutsui
- Department of Anesthesia & Perioperative Care, University of California, San Francisco, San Francisco, CA, United States
| | - Rishi P. Kothari
- Department of Anesthesia & Perioperative Care, University of California, San Francisco, San Francisco, CA, United States
- Department of Anesthesiology & Perioperative Medicine, Thomas Jefferson University, Philadelphia, PA, United States
| | - Dieter Adelmann
- Department of Anesthesia & Perioperative Care, University of California, San Francisco, San Francisco, CA, United States
| | - Jérémie Joffre
- Centre de Recherche Saint-Antoine INSERM U938, Sorbonne University, Paris, France
- Medical Intensive Care Unit, Saint Antoine University Hospital, APHP, Sorbonne University, Paris, France
| | - Judith Hellman
- Department of Anesthesia & Perioperative Care, University of California, San Francisco, San Francisco, CA, United States
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Milewski K, Orzeł-Gajowik K, Zielińska M. Mitochondrial Changes in Rat Brain Endothelial Cells Associated with Hepatic Encephalopathy: Relation to the Blood-Brain Barrier Dysfunction. Neurochem Res 2024; 49:1489-1504. [PMID: 35917006 PMCID: PMC11106209 DOI: 10.1007/s11064-022-03698-7] [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: 08/31/2021] [Revised: 02/17/2022] [Accepted: 07/14/2022] [Indexed: 12/06/2022]
Abstract
The mechanisms underlying cerebral vascular dysfunction and edema during hepatic encephalopathy (HE) are unclear. Blood-brain barrier (BBB) impairment, resulting from increased vascular permeability, has been reported in acute and chronic HE. Mitochondrial dysfunction is a well-documented result of HE mainly affecting astrocytes, but much less so in the BBB-forming endothelial cells. Here we review literature reports and own experimental data obtained in HE models emphasizing alterations in mitochondrial dynamics and function as a possible contributor to the status of brain endothelial cell mitochondria in HE. Own studies on the expression of the mitochondrial fusion-fission controlling genes rendered HE animal model-dependent effects: increase of mitochondrial fusion controlling genes opa1, mfn1 in cerebral vessels in ammonium acetate-induced hyperammonemia, but a decrease of the two former genes and increase of fis1 in vessels in thioacetamide-induced HE. In endothelial cell line (RBE4) after 24 h ammonia and/or TNFα treatment, conditions mimicking crucial aspects of HE in vivo, we observed altered expression of mitochondrial fission/fusion genes: a decrease of opa1, mfn1, and, increase of the fission related fis1 gene. The effect in vitro was paralleled by the generation of reactive oxygen species, decreased total antioxidant capacity, decreased mitochondrial membrane potential, as well as increased permeability of RBE4 cell monolayer to fluorescein isothiocyanate dextran. Electron microscopy documented enlarged mitochondria in the brain endothelial cells of rats in both in vivo models. Collectively, the here observed alterations of cerebral endothelial mitochondria are indicative of their fission, and decreased potential of endothelial mitochondria are likely to contribute to BBB dysfunction in HE.
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Affiliation(s)
- Krzysztof Milewski
- Department of Neurotoxicology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego St. 5, 02-106, Warsaw, Poland.
| | - Karolina Orzeł-Gajowik
- Department of Neurotoxicology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego St. 5, 02-106, Warsaw, Poland
| | - Magdalena Zielińska
- Department of Neurotoxicology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Pawińskiego St. 5, 02-106, Warsaw, Poland.
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Srivastava P, Sudevan ST, Thennavan A, Mathew B, Kanthlal SK. Inhibiting Monoamine Oxidase in CNS and CVS would be a Promising Approach to Mitigating Cardiovascular Complications in Neurodegenerative Disorders. CNS & NEUROLOGICAL DISORDERS DRUG TARGETS 2024; 23:331-341. [PMID: 36872357 DOI: 10.2174/1871527322666230303115236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 12/17/2022] [Accepted: 01/03/2023] [Indexed: 03/07/2023]
Abstract
The flavoenzyme monoamine oxidases (MAOs) are present in the mitochondrial outer membrane and are responsible for the metabolism of biogenic amines. MAO deamination of biological amines produces toxic byproducts such as amines, aldehydes, and hydrogen peroxide, which are significant in the pathophysiology of multiple neurodegenerative illnesses. In the cardiovascular system (CVS), these by-products target the mitochondria of cardiac cells leading to their dysfunction and producing redox imbalance in the endothelium of the blood vessels. This brings up the biological relationship between the susceptibility of getting cardiovascular disorders in neural patients. In the current scenario, MAO inhibitors are highly recommended by physicians worldwide for the therapy and management of various neurodegenerative disorders. Many interventional studies reveal the benefit of MAO inhibitors in CVS. Drug candidates who can target both the central and peripheral MAO could be a better to compensate for the cardiovascular comorbidities observed in neurodegenerative patients.
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Affiliation(s)
- Princika Srivastava
- Department of Pharmacology, Amrita School of Pharmacy, Amrita Vishwa Vidyapeetham, AIMS Health Science Campus, Kochi, 682 041, Kerala, India
| | - Sachithra Thazhathuveedu Sudevan
- Department of Pharmaceutical Chemistry, Amrita School of Pharmacy, Amrita Vishwa Vidyapeetham, AIMS Health Sciences Campus, Kochi, 682 041, India
| | - Arumugam Thennavan
- Central Lab Animal Facility, Amrita Vishwa Vidyapeetham, AIMS Health Science Campus, Kochi, 682 041, Kerala, India
| | - Bijo Mathew
- Department of Pharmaceutical Chemistry, Amrita School of Pharmacy, Amrita Vishwa Vidyapeetham, AIMS Health Sciences Campus, Kochi, 682 041, India
| | - S K Kanthlal
- Department of Pharmacology, Amrita School of Pharmacy, Amrita Vishwa Vidyapeetham, AIMS Health Science Campus, Kochi, 682 041, Kerala, India
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Shi Z, Xi L, Wang Y, Zhao X. Chronic Exposure to Environmental Pollutant Ammonia Causes Damage to the Olfactory System and Behavioral Abnormalities in Mice. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:15412-15421. [PMID: 37787400 DOI: 10.1021/acs.est.3c04875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
Ammonia (NH3) is a major air pollutant. However, few studies have been extended beyond the histopathological changes in the olfactory mucosa to the impact of NH3 exposure on other parts of the olfactory system and olfactory functioning. Therefore, we assessed the effects of exogenous NH3 (either 20 ppm for the low exposure group or 200 ppm for the high exposure group) on the various parts of the olfactory system by histological observation, gene expression, immunochemistry, and chemical analyses. A total of 140 Institute of Cancer Research mice (4 weeks old), 70 females and 70 males (average body weight at the start: 21.5 ± 1.9 g), were used. The exposure lasted for 4 weeks, and the mice were exposed to the NH3 for 4 h per day. Our results showed that chronic exposure to NH3 damaged the olfactory system, with consequences for changing the foraging behavior and anxiety behavior. Our results also suggest that it is plausible that NH3 recruited T cells and activated microglia cells and astrocytes, leading to inflammation in the olfactory system. Increased release of proinflammatory cytokines (TNF-α, IL-1β, IL-6, and interferon-γ) and reduced release of anti-inflammatory cytokines (IL-4 and IFN-beta) led to tissue damage and compromised the functions of the olfactory system.
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Affiliation(s)
- Zhifang Shi
- College of Animal Science and Technology, Henan University of Animal Husbandry and Economy, Zhengzhou, Henan 450046, China
- School of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, China
- Department of Animal Science, McGill University, 21,111 Lakeshore, Ste. Anne de Bellevue, Quebec H9X 3V9, Canada
| | - Lei Xi
- College of Animal Science and Technology, Henan University of Animal Husbandry and Economy, Zhengzhou, Henan 450046, China
| | - Yan Wang
- School of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, China
| | - Xin Zhao
- Department of Animal Science, McGill University, 21,111 Lakeshore, Ste. Anne de Bellevue, Quebec H9X 3V9, Canada
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Grahl MVC, Andrade BDS, Perin APA, Neves GA, Duarte LDS, Uberti AF, Hohl KS, Follmer C, Carlini CR. Could the Urease of the Gut Bacterium Proteus mirabilis Play a Role in the Altered Gut-Brain Talk Associated with Parkinson's Disease? Microorganisms 2023; 11:2042. [PMID: 37630602 PMCID: PMC10459573 DOI: 10.3390/microorganisms11082042] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 08/01/2023] [Accepted: 08/06/2023] [Indexed: 08/27/2023] Open
Abstract
Intestinal dysbiosis seems to play a role in neurodegenerative pathologies. Parkinson's disease (PD) patients have an altered gut microbiota. Moreover, mice treated orally with the gut microbe Proteus mirabilis developed Parkinson's-like symptoms. Here, the possible involvement of P. mirabilis urease (PMU) and its B subunit (PmUreβ) in the pathogenesis of PD was assessed. Purified proteins were given to mice intraperitoneally (20 μg/animal/day) for one week. Behavioral tests were conducted, and brain homogenates of the treated animals were subjected to immunoassays. After treatment with PMU, the levels of TNF-α and IL-1β were measured in Caco2 cells and cellular permeability was assayed in Hek 293. The proteins were incubated in vitro with α-synuclein and examined via transmission electron microscopy. Our results showed that PMU treatment induced depressive-like behavior in mice. No motor deficits were observed. The brain homogenates had an increased content of caspase-9, while the levels of α-synuclein and tyrosine hydroxylase decreased. PMU increased the pro-inflammatory cytokines and altered the cellular permeability in cultured cells. The urease, but not the PmUreβ, altered the morphology of α-synuclein aggregates in vitro, forming fragmented aggregates. We concluded that PMU promotes pro-inflammatory effects in cultured cells. In vivo, PMU induces neuroinflammation and a depressive-like phenotype compatible with the first stages of PD development.
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Affiliation(s)
- Matheus V. C. Grahl
- Graduate Program in Medicine and Health Sciences and Brain Institute, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre 90610-000, RS, Brazil; (M.V.C.G.); (A.F.U.)
- School of Health Sciences, University Center Ritter dos Reis, Porto Alegre 90840-440, RS, Brazil
| | - Brenda da Silva Andrade
- Laboratory of Molecular Pharmacology, Institute of Biomedical Sciences, Health Sciences Center, Federal University of Rio de Janeiro, Rio de Janeiro 21944-590, RJ, Brazil; (B.d.S.A.); (G.A.N.); (L.d.S.D.)
| | - Ana Paula A. Perin
- Graduate Program in Cellular and Molecular Biology, Center of Biotechnology, Federal University of Rio Grande do Sul, Porto Alegre 91501-970, RS, Brazil;
| | - Gilda A. Neves
- Laboratory of Molecular Pharmacology, Institute of Biomedical Sciences, Health Sciences Center, Federal University of Rio de Janeiro, Rio de Janeiro 21944-590, RJ, Brazil; (B.d.S.A.); (G.A.N.); (L.d.S.D.)
| | - Laura de Souza Duarte
- Laboratory of Molecular Pharmacology, Institute of Biomedical Sciences, Health Sciences Center, Federal University of Rio de Janeiro, Rio de Janeiro 21944-590, RJ, Brazil; (B.d.S.A.); (G.A.N.); (L.d.S.D.)
| | - Augusto Frantz Uberti
- Graduate Program in Medicine and Health Sciences and Brain Institute, Pontifical Catholic University of Rio Grande do Sul, Porto Alegre 90610-000, RS, Brazil; (M.V.C.G.); (A.F.U.)
| | - Kelvin Siqueira Hohl
- Graduate Program in Biological Sciences—Biochemistry, Federal University of Rio Grande do Sul, Porto Alegre 90035-003, RS, Brazil;
| | - Cristian Follmer
- Laboratory of Biological Chemistry of Neurodegenerative Disorders, Institute of Chemistry, Department of Physical-Chemistry, Federal University of Rio de Janeiro, Rio de Janeiro 21941-909, RJ, Brazil;
| | - Celia Regina Carlini
- Department of Biochemistry, Federal University of Rio Grande do Sul, Porto Alegre 90035-003, RS, Brazil
- National Institute of Science and Technology in Brain Diseases, Excitotoxity and Neuroprotection (INCT-EN), Porto Alegre 90035-003, RS, Brazil
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Ivnitsky JJ, Schäfer TV, Rejniuk VL, Golovko AI. Endogenous humoral determinants of vascular endothelial dysfunction as triggers of acute poisoning complications. J Appl Toxicol 2023; 43:47-65. [PMID: 35258106 DOI: 10.1002/jat.4312] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 02/13/2022] [Accepted: 02/26/2022] [Indexed: 12/16/2022]
Abstract
The vascular endothelium is not only the semipermeable membrane that separates tissue from blood but also an organ that regulates inflammation, vascular tone, blood clotting, angiogenesis and synthesis of connective tissue proteins. It is susceptible to the direct cytotoxic action of numerous xenobiotics and to the acute hypoxia that accompanies acute poisoning. This damage is superimposed on the preformed state of the vascular endothelium, which, in turn, depends on many humoral factors. The probability that an exogenous toxicant will cause life-threatening dysfunction of the vascular endothelium, thereby complicating the course of acute poisoning, increases with an increase in the content of endogenous substances in the blood that disrupt endothelial function. These include ammonia, bacterial endotoxin, indoxyl sulfate, para-cresyl sulfate, trimethylamine N-oxide, asymmetric dimethylarginine, glucose, homocysteine, low-density and very-low-density lipoproteins, free fatty acids and products of intravascular haemolysis. Some other endogenous substances (albumin, haptoglobin, haemopexin, biliverdin, bilirubin, tetrahydrobiopterin) or food-derived compounds (ascorbic acid, rutin, omega-3 polyunsaturated fatty acids, etc.) reduce the risk of lethal vascular endothelial dysfunction. The individual variability of the content of these substances in the blood contributes to the stochasticity of the complications of acute poisoning and is a promising target for the risk reduction measures. Another feasible option may be the repositioning of drugs that affect the function of the vascular endothelium while being currently used for other indications.
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Affiliation(s)
- Jury Ju Ivnitsky
- Golikov Research Clinical Center of Toxicology under the Federal Medical Biological Agency, Saint Petersburg, Russia
| | - Timur V Schäfer
- State Scientific Research Test Institute of the Military Medicine of Defense Ministry of the Russian Federation, Saint Petersburg, Russia
| | - Vladimir L Rejniuk
- Golikov Research Clinical Center of Toxicology under the Federal Medical Biological Agency, Saint Petersburg, Russia
| | - Alexandr I Golovko
- Golikov Research Clinical Center of Toxicology under the Federal Medical Biological Agency, Saint Petersburg, Russia
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7
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Schäfer TV, Vakunenkova OA, Ivnitsky JJ, Golovko AI. Gut Barrier in Critical States of the Body. BIOLOGY BULLETIN REVIEWS 2022. [PMCID: PMC9297268 DOI: 10.1134/s2079086422040077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The intestinal barrier (IB) is a system of diffusion barriers separating the intestinal chyme and blood. The aim of the review is to identify the role of IB dysfunction in the formation of critical states of the body and to substantiate ways to prevent these states. Toxic substances produced by normal intestinal microflora are characterized. The involvement of endotoxin and ammonia in the pathogenesis of sepsis, acute circulatory disorders, secondary acute pulmonary lesions, and acute cerebral insufficiency is shown. Approaches to protect the IB in critical states of the body are proposed.
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Affiliation(s)
- T. V. Schäfer
- State Scientific Research and Testing Institute of Military Medicine, St. Petersburg, Russia
| | - O. A. Vakunenkova
- Golikov Scientific and Clinical Center of Toxicology, St. Petersburg, Russia
| | - Ju. Ju. Ivnitsky
- Golikov Scientific and Clinical Center of Toxicology, St. Petersburg, Russia
| | - A. I. Golovko
- Golikov Scientific and Clinical Center of Toxicology, St. Petersburg, Russia
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8
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Ivnitsky JJ, Schäfer TV, Rejniuk VL, Vakunenkova OA. Secondary Dysfunction of the Intestinal Barrier in the Pathogenesis of Complications of Acute Poisoning. J EVOL BIOCHEM PHYS+ 2022; 58:1075-1098. [PMID: 36061072 PMCID: PMC9420239 DOI: 10.1134/s0022093022040123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 05/23/2022] [Accepted: 05/24/2022] [Indexed: 11/22/2022]
Abstract
The last decade has been marked by an exponential increase
in the number of publications on the physiological role of the normal
human gut microbiota. The idea of a symbiotic relationship between
the human organism and normal microbiota of its gastrointestinal
tract has been firmly established as an integral part of the current
biomedical paradigm. However, the type of this symbiosis varies
from mutualism to parasitism and depends on the functional state
of the host organism. Damage caused to the organism by external
agents can lead to the emergence of conditionally pathogenic properties
in the normal gut microbiota, mediated by humoral factors and affecting
the outcome of exogenous exposure. Among the substances produced
by symbiotic microbiota, there are an indefinite number of compounds
with systemic toxicity. Some occur in the intestinal chyme in potentially
lethal amounts in the case they enter the bloodstream quickly. The quick
entry of potential toxicants is prevented by the intestinal barrier
(IB), a set of structural elements separating the intestinal chyme
from the blood. Hypothetically, severe damage to the IB caused by
exogenous toxicants can trigger a leakage and subsequent systemic
redistribution of toxic substances of bacterial origin. Until recently,
the impact of such a redistribution on the outcome of acute exogenous
poisoning remained outside the view of toxicology. The present review
addresses causal relationships between the secondary dysfunction
of the IB and complications of acute poisoning. We characterize
acute systemic toxicity of such waste products of the normal gut microflora
as ammonia and endotoxins, and demonstrate their involvement in
the formation of such complications of acute poisoning as shock,
sepsis, cerebral insufficiency and secondary lung injuries. The
principles of assessing the functional state of the IB and the approaches
to its protection in acute poisoning are briefly considered.
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Affiliation(s)
- Ju. Ju. Ivnitsky
- Golikov Research Clinical Center of Toxicology, Federal Medical Biological Agency, St. Petersburg, Russia
| | - T. V. Schäfer
- State Scientific Research Test Institute of Military Medicine, Ministry of Defense of the Russian Federation, St. Petersburg, Russia
| | - V. L. Rejniuk
- Golikov Research Clinical Center of Toxicology, Federal Medical Biological Agency, St. Petersburg, Russia
| | - O. A. Vakunenkova
- Golikov Research Clinical Center of Toxicology, Federal Medical Biological Agency, St. Petersburg, Russia
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Uberti AF, Callai-Silva N, Grahl MVC, Piovesan AR, Nachtigall EG, Furini CRG, Carlini CR. Helicobacter pylori Urease: Potential Contributions to Alzheimer’s Disease. Int J Mol Sci 2022; 23:ijms23063091. [PMID: 35328512 PMCID: PMC8949269 DOI: 10.3390/ijms23063091] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2021] [Revised: 03/09/2022] [Accepted: 03/10/2022] [Indexed: 11/24/2022] Open
Abstract
Alzheimer’s disease (AD) causes dementia and memory loss in the elderly. Deposits of beta-amyloid peptide and hyperphosphorylated tau protein are present in a brain with AD. A filtrate of Helicobacter pylori’s culture was previously found to induce hyperphosphorylation of tau in vivo, suggesting that bacterial exotoxins could permeate the blood–brain barrier and directly induce tau’s phosphorylation. H. pylori, which infects ~60% of the world population and causes gastritis and gastric cancer, produces a pro-inflammatory urease (HPU). Here, the neurotoxic potential of HPU was investigated in cultured cells and in rats. SH-SY5Y neuroblastoma cells exposed to HPU (50–300 nM) produced reactive oxygen species (ROS) and had an increased [Ca2+]i. HPU-treated BV-2 microglial cells produced ROS, cytokines IL-1β and TNF-α, and showed reduced viability. Rats received daily i.p., HPU (5 µg) for 7 days. Hyperphosphorylation of tau at Ser199, Thr205 and Ser396 sites, with no alterations in total tau or GSK-3β levels, and overexpression of Iba1, a marker of microglial activation, were seen in hippocampal homogenates. HPU was not detected in the brain homogenates. Behavioral tests were performed to assess cognitive impairments. Our findings support previous data suggesting an association between infection by H. pylori and tauopathies such as AD, possibly mediated by its urease.
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Affiliation(s)
- Augusto F. Uberti
- Laboratory of Neurotoxins, Brain Institute of Rio Grande do Sul (BRAINS) and Graduate Program in Medicine and Health Sciences, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre CEP 90610-000, RS, Brazil; (A.F.U.); (N.C.-S.); (M.V.C.G.)
| | - Natalia Callai-Silva
- Laboratory of Neurotoxins, Brain Institute of Rio Grande do Sul (BRAINS) and Graduate Program in Medicine and Health Sciences, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre CEP 90610-000, RS, Brazil; (A.F.U.); (N.C.-S.); (M.V.C.G.)
| | - Matheus V. C. Grahl
- Laboratory of Neurotoxins, Brain Institute of Rio Grande do Sul (BRAINS) and Graduate Program in Medicine and Health Sciences, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre CEP 90610-000, RS, Brazil; (A.F.U.); (N.C.-S.); (M.V.C.G.)
| | - Angela R. Piovesan
- Center of Biotechnology, Graduate Program in Cellular and Molecular Biology, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre CEP 91501-970, RS, Brazil;
| | - Eduarda G. Nachtigall
- Laboratory of Cognition and Memory Neurobiology, Brain Institute of Rio Grande do Sul (BRAINS) and Graduate Program in Biomedical Gerontology, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre CEP 90610-000, RS, Brazil; (E.G.N.); (C.R.G.F.)
| | - Cristiane R. G. Furini
- Laboratory of Cognition and Memory Neurobiology, Brain Institute of Rio Grande do Sul (BRAINS) and Graduate Program in Biomedical Gerontology, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre CEP 90610-000, RS, Brazil; (E.G.N.); (C.R.G.F.)
| | - Celia Regina Carlini
- Laboratory of Neurotoxins, Brain Institute of Rio Grande do Sul (BRAINS) and Graduate Program in Medicine and Health Sciences, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre CEP 90610-000, RS, Brazil; (A.F.U.); (N.C.-S.); (M.V.C.G.)
- Correspondence: ; Tel.: +55-51-3320-5986
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10
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Pan R, Yu S, Zhang H, Timmins GS, Weaver J, Yang Y, Zhou X, Liu KJ. Endogenous zinc protoporphyrin formation critically contributes to hemorrhagic stroke-induced brain damage. J Cereb Blood Flow Metab 2021; 41:3232-3247. [PMID: 34187233 PMCID: PMC8669275 DOI: 10.1177/0271678x211028475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hemorrhagic stroke is a leading cause of death. The causes of intracerebral hemorrhage (ICH)-induced brain damage are thought to include lysis of red blood cells, hemin release and iron overload. These mechanisms, however, have not proven very amenable to therapeutic intervention, and so other mechanistic targets are being sought. Here we report that accumulation of endogenously formed zinc protoporphyrin (ZnPP) also critically contributes to ICH-induced brain damage. ICH caused a significant accumulation of ZnPP in brain tissue surrounding hematoma, as evidenced by fluorescence microscopy of ZnPP, and further confirmed by fluorescence spectroscopy and supercritical fluid chromatography-mass spectrometry. ZnPP formation was dependent upon both ICH-induced hypoxia and an increase in free zinc accumulation. Notably, inhibiting ferrochelatase, which catalyzes insertion of zinc into protoporphyrin, greatly decreased ICH-induced endogenous ZnPP generation. Moreover, a significant decrease in brain damage was observed upon ferrochelatase inhibition, suggesting that endogenous ZnPP contributes to the damage in ICH. Our findings reveal a novel mechanism of ICH-induced brain damage through ferrochelatase-mediated formation of ZnPP in ICH tissue. Since ferrochelatase can be readily inhibited by small molecules, such as protein kinase inhibitors, this may provide a promising new and druggable target for ICH therapy.
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Affiliation(s)
- Rong Pan
- Department of Pharmaceutical Sciences, University of New Mexico Health Sciences Center, Albuquerque, USA
| | - Song Yu
- Department of Pharmaceutical Sciences, University of New Mexico Health Sciences Center, Albuquerque, USA
| | - Haikun Zhang
- Department of Pharmaceutical Sciences, University of New Mexico Health Sciences Center, Albuquerque, USA
| | - Graham S Timmins
- Department of Pharmaceutical Sciences, University of New Mexico Health Sciences Center, Albuquerque, USA
| | - John Weaver
- Department of Pharmaceutical Sciences, University of New Mexico Health Sciences Center, Albuquerque, USA
| | - Yirong Yang
- Department of Pharmaceutical Sciences, University of New Mexico Health Sciences Center, Albuquerque, USA
| | - Xixi Zhou
- Department of Pharmaceutical Sciences, University of New Mexico Health Sciences Center, Albuquerque, USA
| | - Ke Jian Liu
- Department of Pharmaceutical Sciences, University of New Mexico Health Sciences Center, Albuquerque, USA
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11
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Zaragozá R. Transport of Amino Acids Across the Blood-Brain Barrier. Front Physiol 2020; 11:973. [PMID: 33071801 PMCID: PMC7538855 DOI: 10.3389/fphys.2020.00973] [Citation(s) in RCA: 83] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 07/16/2020] [Indexed: 01/17/2023] Open
Abstract
The blood-brain-barrier (BBB), present in brain capillaries, constitutes an essential barrier mechanism for normal functioning and development of the brain. The presence of tight junctions between adjacent endothelial cells restricts permeability and movement of molecules between extracellular fluid and plasma. The protein complexes that control cell-cell attachment also polarize cellular membrane, so that it can be divided into luminal (blood-facing) and abluminal (brain) sides, and each solute that enters/leaves the brain must cross both membranes. Several amino acid (AA) transport systems with different distributions on both sides of the BBB have been described. In a broad sense, there are at least five different systems of facilitative transporters and all of them are found in the luminal membrane. Some of these transporters are very specific for a small group of substrates and are located exclusively on the luminal side of the BBB. However, the two major facilitative carriers, system L and system y+, are located in both membranes, although asymmetrically. The position of these Na+-independent transporters ensures AA availability in the brain and also its bidirectional transport across the endothelial cells. On the other hand, there are several Na+-dependent transport systems that transport AAs against its concentration gradient together with the movement of Na+ ions. The majority of these active transporters are present exclusively at the abluminal membrane and are responsible for AA efflux from the brain into the endothelial cells. Since they are Na+-coupled, the sodium pump Na+/K+-ATPase is also highly expressed on this abluminal side of the BBB. Once inside the cell, the facilitative transporters located in the luminal membranes mediate export from the endothelial cell to the blood. In summary, the polarized distribution of these transport systems between the luminal and abluminal membranes, and the fact that more than one transporter may carry the same substrate, ensures supply and excretion of AAs in and out of the brain, thereby controlling its homeostasis and proper function.
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Affiliation(s)
- Rosa Zaragozá
- Department of Human Anatomy and Embriology, School of Medicine, IIS INCLIVA, University of Valencia, Valencia, Spain
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12
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Exchange-mode glutamine transport across CNS cell membranes. Neuropharmacology 2019; 161:107560. [PMID: 30853601 DOI: 10.1016/j.neuropharm.2019.03.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 02/28/2019] [Accepted: 03/02/2019] [Indexed: 12/18/2022]
Abstract
CNS cell membranes possess four transporters capable of exchanging Lglutamine (Gln) for other amino acids: the large neutral amino acid (LNAA) transporters LAT1 and LAT2, the hybrid basic amino acid (L-arginine (Arg), L-leucine (Leu)/LNAA transporter y+LAT2, and the L-alanine/L-serine/L-cysteine transporter 2 (ASCT2). LAT1/LAT2 and y+LAT2 are present in astrocytes, neurons and the blood brain barrier (BBB) - forming cerebral vascular endothelial cells (CVEC), while the location of ASCT2 in the individual cell types is a matter of debate. In the healthy brain, contribution of the exchangers to Gln shuttling from astrocytes to neurons and thus their role in controlling the conversion of Gln to the amino acid neurotransmitters l-glutamate (Glu) and γ-aminobutyric acid (GABA) and Gln flux across the BBB appears negligible as compared to the system A and system N uniporters. Insofar, except for the contribution of LAT1 to the maintenance of Gln homeostasis in the interstitial fluid (ISF), no well-defined CNS-specific function has been established for either of the three transporters in the healthy brain. The Gln-accepting amino acid exchangers appear to gain significance under conditions of excessive brain Gln load (glutaminosis). Excess Gln efflux across the BBB enhances influx into the brain of L-tryptophan (Trp). Excess of Trp is responsible for overloading the brain with neuroactive compounds: serotonin, kynurenic acid, quinolinic acid and/or oxindole, which contribute to neurotransmission imbalance accompanying hyperammonemia. In turn, alterations of y+LAT2-mediated Gln/Arg exchange and Arg uptake in astrocyte, modulate astrocytic nitric oxide synthesis and oxidative/nitrosative stress in ammonia-overexposed brain. This article is part of the issue entitled 'Special Issue on Neurotransmitter Transporters'.
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13
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Xiao R, Yuan L, He W, Yang X. Zinc ions regulate opening of tight junction favouring efflux of macromolecules via the GSK3β/snail-mediated pathway. Metallomics 2019; 10:169-179. [PMID: 29292464 DOI: 10.1039/c7mt00288b] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Zinc is an essential trace element presenting in particularly high concentration in the brain. In some regions, e.g. lateral amygdala, subiculum and hippocampus, rapidly-exchangeable zinc may transiently reach even up to 600 μM. To explore the possible roles of high-concentration Zn2+ in regulating the blood-brain barrier (BBB), we investigated the effects of Zn2+ on the functions and structures of the tight junction (TJ) with an in vitro model of a Madin-Darby canine kidney (MDCK) cell monolayer. The experimental results indicated that high concentrations (>200 μM) of Zn2+ can affect the TJ integrity in a polarized manner. Basolateral addition of Zn2+ led to reversible TJ opening with pore paths of r ∼ 2 nm or more depending on Zn2+ concentration. The efflux/influx ratios of different sized probes were found to be ∼4.6 for FD4 (MW 4000) and ∼1.8 for Eu-DTPA (MW 560), suggesting that the Zn2+-induced paracelluar channels favour efflux especially for macromolecules. Further mechanistic studies revealed that the elevated intracellular Zn2+ taken from the basolateral side can increase phosphorylation of glycogen synthase kinase (GSK) 3β, primarily due to the inhibition of calcineurin (CaN), thus resulting in the elevation of the snail transcriptional repressors. Subsequently, Zn2+ can cause the down-regulation of claudin-1, breakage of occludin and ZO-1 rings, and collapse of basolateral F-actin structures. These overall factors result in the formation of a trumpet-like paracellular channel, which allows asymmetric solute permeation. The ERK1/2 and JNK1/2 pathways may also be involved in the Zn2+-induced TJ opening process, while the activation of matrix metalloproteinase was not observed. Our results may suggest a potential role of zinc in regulation of BBB permeability associated with brain clearance of metabolites through the glymphatic system.
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Affiliation(s)
- Ruyue Xiao
- State Key laboratories of Natural and Mimetic Drugs and Department of Chemical Biology, School of Pharmaceutical Sciences, Peking University Health Science Center, Beijing 100191, China.
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14
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Jayakumar AR, Norenberg MD. Hyperammonemia in Hepatic Encephalopathy. J Clin Exp Hepatol 2018; 8:272-280. [PMID: 30302044 PMCID: PMC6175739 DOI: 10.1016/j.jceh.2018.06.007] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2018] [Accepted: 06/10/2018] [Indexed: 12/12/2022] Open
Abstract
The precise mechanism underlying the neurotoxicity of Hepatic Encephalopathy (HE) is remains unclear. The dominant view has been that gut-derived nitrogenous toxins are not extracted by the diseased liver and thereby enter the brain. Among the various toxins proposed, the case for ammonia is most compelling. Events that lead to increased levels of blood or brain ammonia have been shown to worsen HE, whereas reducing blood ammonia levels alleviates HE. Clinical, pathological, and biochemical changes observed in HE can be reproduced by increasing blood or brain ammonia levels in experimental animals, while exposure of cultured astrocytes to ammonium salts reproduces the morphological and biochemical findings observed in HE. However, factors other than ammonia have recently been proposed to be involved in the development of HE, including cytokines and other blood and brain immune factors. Moreover, recent studies have questioned the critical role of ammonia in the pathogenesis of HE since blood ammonia levels do not always correlate with the level/severity of encephalopathy. This review summarizes the vital role of ammonia in the pathogenesis of HE in humans, as well as in experimental models of acute and chronic liver failure. It further emphasizes recent advances in the molecular mechanisms involved in the progression of neurological complications that occur in acute and chronic liver failure.
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Key Words
- AHE, Acute Hepatic Encephalopathy
- ALF, Acute Liver Failure
- CHE, Chronic Hepatic Encephalopathy
- CNS, Central Nervous System
- CSF, Cerebrospinal Fluid
- ECs, Endothelial Cells
- HE, Hepatic Encephalopathy
- IL, Interleukin
- LPS, Lipopolysaccharide
- MAPKs, Mitogen-Activated Protein Kinases
- NCX, Sodium-Calcium Exchanger
- NF-κB, Nuclear Factor-kappaB
- NHE, Sodium/Hydrogen Exchanger-1 or SLC9A1 (SoLute Carrier Family 9A1)
- SUR1, The Sulfonylurea Receptor 1
- TDP-43 and tau proteinopathies
- TDP-43, TAR DNA-Binding Protein, 43 kDa
- TLR, Toll-like Receptor
- TNF-α, Tumor Necrosis Factor-Alpha
- TSP-1, Thrombospondin-1
- ammonia
- hepatic encephalopathy
- inflammation
- matricellular proteins
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Affiliation(s)
- A R Jayakumar
- General Medical Research, Neuropathology Section, R&D Service, Veterans Affairs Medical Center, Miami, FL 33125, United States
- South Florida VA Foundation for Research and Education Inc., Veterans Affairs Medical Center, Miami, FL 33125, United States
| | - Michael D Norenberg
- Department of Pathology, University of Miami School of Medicine, Miami, FL 33125, United States
- Department of Biochemistry & Molecular Biology, University of Miami School of Medicine, Miami, FL 33125, United States
- Department of Neurology and Neurological Surgery, University of Miami School of Medicine, Miami, FL 33125, United States
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15
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Li QQ, Li LJ, Wang XY, Sun YY, Wu J. Research Progress in Understanding the Relationship Between Heme Oxygenase-1 and Intracerebral Hemorrhage. Front Neurol 2018; 9:682. [PMID: 30177908 PMCID: PMC6109777 DOI: 10.3389/fneur.2018.00682] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 07/30/2018] [Indexed: 01/14/2023] Open
Abstract
Intracerebral hemorrhage (ICH) is a fatal acute cerebrovascular disease, with a high morbidity and mortality. Following ICH, erythrocytes release heme and several of its metabolites, thereby contributing to brain edema and secondary brain damage. Heme oxygenase is the initial and rate-limiting enzyme of heme catabolism, and the expression of heme oxygenase-1 (HO-1) is rapidly induced following acute brain injury. As HO-1 exerts it effects via various metabolites, its role during ICH remains complex. Therefore, in-depth studies regarding the role of HO-1 in secondary brain damage following ICH may provide a theoretical basis for neuroprotective function after ICH. The present review aims to summarize recent key studies regarding the effects of HO-1 following ICH, as well as its influence on ICH prognosis.
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Affiliation(s)
- Qian-Qian Li
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Lan-Jun Li
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Xin-Yu Wang
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Yu-Ying Sun
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
| | - Jun Wu
- Department of Neurology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou University, Zhengzhou, China
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16
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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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17
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Maines E, Piccoli G, Pascarella A, Colucci F, Burlina AB. Inherited hyperammonemias: a Contemporary view on pathogenesis and diagnosis. Expert Opin Orphan Drugs 2017. [DOI: 10.1080/21678707.2018.1409108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Evelina Maines
- Pediatric Unit, Provincial Centre for Rare Diseases, Department of Women’s and Children’s Health, Azienda Provinciale per i Servizi Sanitari, Trento, Italy
| | - Giovanni Piccoli
- CIBIO - Centre for integrative biology, Università degli Studi di Trento, Italy & Dulbecco Telethon Institute, Trento, Italy
| | - Antonia Pascarella
- Division of Inherited Metabolic Diseases, Reference Centre Expanded Newborn Screening, Department of Women’s and Children’s Health, University Hospital, Padova, Italy
| | - Francesca Colucci
- Division of Inherited Metabolic Diseases, Reference Centre Expanded Newborn Screening, Department of Women’s and Children’s Health, University Hospital, Padova, Italy
| | - Alberto B. Burlina
- Division of Inherited Metabolic Diseases, Reference Centre Expanded Newborn Screening, Department of Women’s and Children’s Health, University Hospital, Padova, Italy
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18
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Milewski K, Bogacińska-Karaś M, Fręśko I, Hilgier W, Jaźwiec R, Albrecht J, Zielińska M. Ammonia Reduces Intracellular Asymmetric Dimethylarginine in Cultured Astrocytes Stimulating Its y⁺LAT2 Carrier-Mediated Loss. Int J Mol Sci 2017; 18:ijms18112308. [PMID: 29099056 PMCID: PMC5713277 DOI: 10.3390/ijms18112308] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 10/19/2017] [Accepted: 10/27/2017] [Indexed: 01/24/2023] Open
Abstract
Previously we had shown that ammonia stimulates nitric oxide (NO) synthesis in astrocytes by increasing the uptake of the precursor amino acid, arginine via the heteromeric arginine/glutamine transporter y+LAT2. Ammonia also increases the concentration in the brain of the endogenous inhibitor of nitric oxide synthases (NOS), asymmetric dimethylarginine (ADMA), but distribution of ADMA surplus between the intraastrocytic and extracellular compartments of the brain has not been studied. Here we tested the hypothesis that ammonia modulates the distribution of ADMA and its analog symmetric dimethylarginine (SDMA) between the two compartments of the brain by competition with arginine for the y+LAT2 transporter. In extension of the hypothesis we analyzed the ADMA/Arg interaction in endothelial cells forming the blood-brain barrier. We measured by high-performance liquid chromatography (HPLC) and mass spectrometry (MS) technique the concentration of arginine, ADMA and SDMA in cultured cortical astrocytes and in a rat brain endothelial cell line (RBE-4) treated with ammonia and the effect of silencing the expression of a gene coding y+LAT2. We also tested the expression of ADMA metabolism enzymes: protein arginine methyltransferase (PRMT) and dimethylarginine dimethyl aminohydrolase (DDAH) and arginine uptake to astrocytes. Treatment for 48 h with 5 mM ammonia led to an almost 50% reduction of ADMA and SDMA concentration in both cell types, and the effect in astrocytes was substantially attenuated by silencing of the Slc7a6 gene. Moreover, the y+LAT2-dependent component of ammonia-evoked arginine uptake in astrocytes was reduced in the presence of ADMA in the medium. Our results suggest that increased ADMA efflux mediated by upregulated y+LAT2 may be a mechanism by which ammonia interferes with intra-astrocytic (and possibly intra-endothelial cell) ADMA content and subsequently, NO synthesis in both cell types.
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Affiliation(s)
- Krzysztof Milewski
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, 02-106 Warsaw, Poland.
| | - Małgorzata Bogacińska-Karaś
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, 02-106 Warsaw, Poland.
| | - Inez Fręśko
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, 02-106 Warsaw, Poland.
| | - Wojciech Hilgier
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, 02-106 Warsaw, Poland.
| | - Radosław Jaźwiec
- Mass Spectrometry Laboratory, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, 02-106 Warsaw, Poland.
| | - Jan Albrecht
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, 02-106 Warsaw, Poland.
| | - Magdalena Zielińska
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, 02-106 Warsaw, Poland.
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19
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Dhanda S, Sandhir R. Blood-Brain Barrier Permeability Is Exacerbated in Experimental Model of Hepatic Encephalopathy via MMP-9 Activation and Downregulation of Tight Junction Proteins. Mol Neurobiol 2017; 55:3642-3659. [PMID: 28523565 DOI: 10.1007/s12035-017-0521-7] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 04/06/2017] [Indexed: 12/27/2022]
Abstract
The present study was designed to investigate the mechanisms involved in blood-brain barrier (BBB) permeability in bile duct ligation (BDL) model of chronic hepatic encephalopathy (HE). Four weeks after BDL surgery, a significant increase was observed in serum bilirubin levels. Masson trichrome staining revealed severe hepatic fibrosis in the BDL rats. 99mTc-mebrofenin retention was increased in the liver of BDL rats suggesting impaired hepatobiliary transport. An increase in permeability to sodium fluorescein, Evans blue, and fluorescein isothiocyanate (FITC)-dextran along with increase in water and electrolyte content was observed in brain regions of BDL rats suggesting disrupted BBB. Increased brain water content can be attributed to increase in aquaporin-4 mRNA and protein expression in BDL rats. Matrix metalloproteinase-9 (MMP-9) mRNA and protein expression was increased in brain regions of BDL rats. Additionally, mRNA and protein expression of tissue inhibitor of matrix metalloproteinases (TIMPs) was also increased in different regions of brain. A significant decrease in mRNA expression and protein levels of tight junction proteins, viz., occludin, claudin-5, and zona occluden-1 (ZO-1) was observed in different brain regions of BDL rats. VCAM-1 mRNA and protein expression was also found to be significantly upregulated in different brain regions of BDL animals. The findings from the study suggest that increased BBB permeability in HE involves activation of MMP-9 and loss of tight junction proteins.
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Affiliation(s)
- Saurabh Dhanda
- Department of Biochemistry, Basic Medical Science Block-II, Sector-25, Panjab University, Chandigarh, 160014, India
| | - Rajat Sandhir
- Department of Biochemistry, Basic Medical Science Block-II, Sector-25, Panjab University, Chandigarh, 160014, India.
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20
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Emerging role of monoamine oxidase as a therapeutic target for cardiovascular disease. Curr Opin Pharmacol 2017; 33:64-69. [PMID: 28528298 DOI: 10.1016/j.coph.2017.04.003] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 03/28/2017] [Accepted: 04/19/2017] [Indexed: 11/23/2022]
Abstract
In the past decade, accumulating evidence highlighted the role of monoamine oxidases (MAOs) in cardiovascular disease (CVD). MAOs are flavoenzymes located in the outer mitochondrial membrane, responsible for the degradation of neurotransmitters and biogenic amines. During this process they generate hydrogen peroxide, aldehydes and ammonia, species that can target mitochondria and induce mitochondrial dysfunction and cardiomyocyte death. Indeed, MAO inhibition affords cardioprotection in several models of CVD, such as ischemia/reperfusion, heart failure and diabetes. Importantly, a few studies provided encouraging results suggesting that MAO inhibition might be beneficial also in patients with CVD. Thus, selective and reversible MAO inhibitors, currently used as therapy for depression and neurodegenerative disorders, might be considered as candidate drugs for the treatment of CVD.
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21
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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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22
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Jang SY, Chang JY. Pathophysiology and Treatment of Cerebral Edema in Acute Liver Failure. JOURNAL OF NEUROCRITICAL CARE 2016. [DOI: 10.18700/jnc.160088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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23
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Bartolić M, Vovk A, Šuput D. Effects of NH 4CL application and removal on astrocytes and endothelial cells. Cell Mol Biol Lett 2016; 21:13. [PMID: 28536616 PMCID: PMC5414667 DOI: 10.1186/s11658-016-0011-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 12/29/2015] [Indexed: 02/07/2023] Open
Abstract
Background Hepatic encephalopathy (HE) is a complex disorder associated with increased ammonia levels in the brain. Although astrocytes are believed to be the principal cells affected in hyperammonemia (HA), endothelial cells (ECs) may also play an important role by contributing to the vasogenic effect of HA. Methods Following acute application and removal of NH4Cl on astrocytes and endothelial cells, we analyzed pH changes, using fluorescence imaging with BCECF/AM, and changes in intracellular Ca2+ concentration ([Ca2+]i), employing fluorescence imaging with Fura-2/AM. Using confocal microscopy, changes in cell volume were observed accompanied by changes of [Ca2+]i in astrocytes and ECs. Results Exposure of astrocytes and ECs to 1 – 20 mM NH4Cl resulted in rapid concentration-dependent alkalinization of cytoplasm followed by slow recovery. Removal of the NH4Cl led to rapid concentration-dependent acidification, again followed by slow recovery. Following the application of NH4Cl, a transient, concentration-dependent rise in [Ca2+]i in astrocytes was observed. This was due to the release of Ca2+ from intracellular stores, since the response was abolished by emptying intracellular stores with thapsigargin and ATP, and was still present in the Ca2+-free bathing solution. The removal of NH4Cl also led to a transient concentration-dependent rise in [Ca2+]i that resulted from Ca2+ release from cytoplasmic proteins, since removing Ca2+ from the bathing solution and emptying intracellular Ca2+ stores did not eliminate the rise. Similar results were obtained from experiments on ECs. Following acute application and removal of NH4Cl no significant changes in astrocyte volume were detected; however, an increase of EC volume was observed after the administration of NH4Cl, and EC shrinkage was demonstrated after the acute removal of NH4Cl. Conclusions This study reveals new data which may give a more complete insight into the mechanism of development and treatment of HE.
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Affiliation(s)
- Miha Bartolić
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška cesta 4, 1000 Ljubljana, Slovenia
| | - Andrej Vovk
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška cesta 4, 1000 Ljubljana, Slovenia
| | - Dušan Šuput
- Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloška cesta 4, 1000 Ljubljana, Slovenia
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Nałęcz KA. Solute Carriers in the Blood–Brain Barier: Safety in Abundance. Neurochem Res 2016; 42:795-809. [DOI: 10.1007/s11064-016-2030-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Revised: 07/29/2016] [Accepted: 08/02/2016] [Indexed: 12/22/2022]
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25
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Multifactorial Effects on Different Types of Brain Cells Contribute to Ammonia Toxicity. Neurochem Res 2016; 42:721-736. [PMID: 27286679 DOI: 10.1007/s11064-016-1966-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 05/20/2016] [Accepted: 05/24/2016] [Indexed: 12/12/2022]
Abstract
Effects of ammonia on astrocytes play a major role in hepatic encephalopathy, acute liver failure and other diseases caused by increased arterial ammonia concentrations (e.g., inborn errors of metabolism, drug or mushroom poisoning). There is a direct correlation between arterial ammonia concentration, brain ammonia level and disease severity. However, the pathophysiology of hyperammonemic diseases is disputed. One long recognized factor is that increased brain ammonia triggers its own detoxification by glutamine formation from glutamate. This is an astrocytic process due to the selective expression of the glutamine synthetase in astrocytes. A possible deleterious effect of the resulting increase in glutamine concentration has repeatedly been discussed and is supported by improvement of some pathologic effects by GS inhibition. However, this procedure also inhibits a large part of astrocytic energy metabolism and may prevent astrocytes from responding to pathogenic factors. A decrease of the already low glutamate concentration in astrocytes due to increased synthesis of glutamine inhibits the malate-aspartate shuttle and energy metabolism. A more recently described pathogenic factor is the resemblance between NH4+ and K+ in their effects on the Na+,K+-ATPase and the Na+,K+, 2 Cl- and water transporter NKCC1. Stimulation of the Na+,K+-ATPase driven NKCC1 in both astrocytes and endothelial cells is essential for the development of brain edema. Na+,K+-ATPase stimulation also activates production of endogenous ouabains. This leads to oxidative and nitrosative damage and sensitizes NKCC1. Administration of ouabain antagonists may accordingly have therapeutic potential in hyperammonemic diseases.
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Mohammadi MT. Overproduction of nitric oxide intensifies brain infarction and cerebrovascular damage through reduction of claudin-5 and ZO-1 expression in striatum of ischemic brain. Pathol Res Pract 2015; 212:959-964. [PMID: 27665022 DOI: 10.1016/j.prp.2015.12.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 12/02/2015] [Accepted: 12/09/2015] [Indexed: 12/14/2022]
Abstract
Nitric oxide (NO) overproduction has been demonstrated from different NO-synthase overexpression or hyperactivity after brain ischemia. Here, we examined the effects of inhibition of NO overproduction on brain infarction, cerebrovascular damage and expression of claudin-5 and zonula occludens-1 (ZO-1) in striatum of ischemic brain. The experiment was performed in three groups of rats; sham, control ischemia and ischemic treatment. Brain ischemia was induced by 60min of middle cerebral artery occlusion (MCAO) followed by 24h of reperfusion. Treated rats received L-NAME 30min before induction of ischemia (1mg/kg, i.p.). Infarct volume and histopathological changes of ischemic striatum were assessed by TTC and LFB staining methods, respectively. Ultimately, quantitative RT-PCR was used for assessment of claudins-5 and ZO-1 expression. MCAO in the control group induced infarction (135±25mm3) at large areas of striatum in accompany with neuronal damages, whereas L-NAME significantly reduced infarction (87±16mm3) and neuronal injuries. The mRNA of ZO-1 and claudin-5 decreased in ischemic striatum, whereas inhibition of NO overproduction by L-NAME attenuated this reduction for these genes. Our findings indicated that NO overproduction after brain ischemia plays a crucial role in neuronal damage especially at striatal regions. Hence, inhibition of excessive NO production may save striatal cerebrovascular integrity of ischemic brain.
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Affiliation(s)
- Mohammad Taghi Mohammadi
- Department of Physiology and Biophysics, School of Medicine, Baqiyatallah University of Medical Sciences, Tehran, Iran.
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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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Miah MK, Shaik IH, Bickel U, Mehvar R. Effects of Pringle maneuver and partial hepatectomy on the pharmacokinetics and blood-brain barrier permeability of sodium fluorescein in rats. Brain Res 2015; 1618:249-60. [PMID: 26051428 DOI: 10.1016/j.brainres.2015.05.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 05/26/2015] [Accepted: 05/28/2015] [Indexed: 10/23/2022]
Abstract
Liver diseases are known to affect the function of remote organs. The aim of the present study was to investigate the effects of Pringle maneuver, which results in hepatic ischemia-reperfusion (IR) injury, and partial hepatectomy (Hx) on the pharmacokinetics and brain distribution of sodium fluorescein (FL), which is a widely used marker of blood-brain barrier (BBB) permeability. Rats were subjected to Pringle maneuver (total hepatic ischemia) for 20 min with (HxIR) or without (IR) 70% hepatectomy. Sham-operated animals underwent laparotomy only. After 15 min or 8h of reperfusion, a single 25-mg/kg dose of FL was injected intravenously and serial (0-30 min) blood and bile and terminal brain samples were collected. Total and free (ultrafiltration) plasma, total brain homogenate, and bile concentrations of FL and/or its glucuronidated metabolite (FL-Glu) were determined by HPLC. Both IR and HxIR caused significant reductions in the biliary excretions of FL and FL-Glu, resulting in significant increases in the plasma AUC of the marker. Additionally, the free fraction of FL in plasma was significantly increased by HxIR. Although the brain concentrations of FL were increased by almost twofold in both IR and HxIR animals, the brain concentrations corrected by the free FL AUC (and not the total AUC) were similar in both groups at either time points. It is concluded that Pringle maneuver and/or partial hepatectomy substantially alters the hepatobiliary disposition, plasma AUC, plasma free fraction, and brain accumulation of FL without altering the BBB permeability to the marker.
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Affiliation(s)
- Mohammad K Miah
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA
| | - Imam H Shaik
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA
| | - Ulrich Bickel
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA; Center for Blood-Brain Barrier Research, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA
| | - Reza Mehvar
- Department of Pharmaceutical Sciences, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA; Center for Blood-Brain Barrier Research, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX, USA; Department of Biomedical and Pharmaceutical Sciences, Chapman University, School of Pharmacy, Irvine, CA, USA.
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Abstract
Amyotrophic lateral sclerosis (ALS) is a dreadful, devastating and incurable motor neuron disease. Aetiologically, it is a multigenic, multifactorial and multiorgan disease. Despite intense research, ALS pathology remains unexplained. Following extensive literature review, this paper posits a new integrative explanation. This framework proposes that ammonia neurotoxicity is a main player in ALS pathogenesis. According to this explanation, a combination of impaired ammonia removal- mainly because of impaired hepatic urea cycle dysfunction-and increased ammoniagenesis- mainly because of impaired glycolytic metabolism in fast twitch skeletal muscle-causes chronic hyperammonia in ALS. In the absence of neuroprotective calcium binding proteins (calbindin, calreticulin and parvalbumin), elevated ammonia-a neurotoxin-damages motor neurons. Ammonia-induced motor neuron damage occurs through multiple mechanisms such as macroautophagy-endolysosomal impairment, endoplasmic reticulum (ER) stress, CDK5 activation, oxidative/nitrosative stress, neuronal hyperexcitability and neuroinflammation. Furthermore, the regional pattern of calcium binding proteins' loss, owing to either ER stress and/or impaired oxidative metabolism, determines clinical variability of ALS. Most importantly, this new framework can be generalised to explain other neurodegenerative disorders such as Huntington's disease and Parkinsonism.
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Affiliation(s)
- Bhavin Parekh
- Department of Biomedical Science, University of Sheffield, Sheffield, S10 2TN, UK
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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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Xie Y, Mao Y, Xu S, Zhou H, Duan X, Cui W, Zhang J, Xu G. Heme-heme oxygenase 1 system is involved in ammonium tolerance by regulating antioxidant defence in Oryza sativa. PLANT, CELL & ENVIRONMENT 2015; 38:129-43. [PMID: 24905845 DOI: 10.1111/pce.12380] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2014] [Revised: 05/25/2014] [Accepted: 05/27/2014] [Indexed: 05/22/2023]
Abstract
Despite substantial evidence showing the ammonium-altered redox homeostasis in plants, the involvement and molecular mechanism of heme-heme oxygenase 1 (heme-HO1), a novel antioxidant system, in the regulation of ammonium tolerance remain elusive. To fill in these gaps, the biological function of rice HO1 (OsSE5) was investigated. Results showed that NH4 Cl up-regulated rice OsSE5 expression. Oxidative stress and subsequent growth inhibition induced by excess NH4 Cl was partly mitigated by pretreatment with carbon monoxide (CO, a by-product of HO1 activity) or intensified by zinc protoporphyrin (ZnPP, a potent inhibitor of HO1 activity). Pretreatment with HO1 inducer hemin, not only up-regulated OsSE5 expression and HO activity, but also rescued the down-regulation of antioxidant transcripts, total and related isozymatic activities, thus significantly counteracting the excess NH4 Cl-triggered reactive oxygen species overproduction, lipid peroxidation and growth inhibition. OsSE5 RNAi transgenic rice plants revealed NH4 Cl-hypersensitive phenotype with impaired antioxidant defence, both of which could be rescued by CO but not hemin. Transgenic Arabidopsis plants over-expressing OsSE5 also exhibited enhanced tolerance to NH4 Cl, which might be attributed to the up-regulation of several antioxidant transcripts. Altogether, these results illustrated the involvement of heme-HO1 system in ammonium tolerance by enhancing antioxidant defence, which may improve plant tolerance to excess ammonium fertilizer.
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Affiliation(s)
- Yanjie Xie
- State Key Laboratory of Crop Genetics and Germplasm Enhancement, Nanjing Agricultural University, Nanjing, 210095, China; MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Nanjing Agricultural University, Nanjing, 210095, China; Laboratory Center of Life Sciences, College of Life Sciences, Nanjing Agricultural University, Nanjing, 210095, China
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Zhang J, Zhang M, Sun B, Li Y, Xu P, Liu C, Liu L, Liu X. Hyperammonemia enhances the function and expression of P-glycoprotein and Mrp2 at the blood-brain barrier through NF-κB. J Neurochem 2014; 131:791-802. [PMID: 25200138 DOI: 10.1111/jnc.12944] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 08/08/2014] [Accepted: 09/05/2014] [Indexed: 01/17/2023]
Abstract
Ammonia is considered to be the main neurotoxin responsible for hepatic encephalopathy resulting from liver failure. Liver failure has been reported to alter expression and activity of P-glycoprotein (P-gp) and multidrug resistance-associated protein 2 (Mrp2) at the blood-brain barrier (BBB). The aim of this study was to investigate whether ammonia is involved in abnormalities of expression and activity of P-gp and Mrp2 at the BBB. Hyperammonemic rats were developed by an intraperitoneal injection of ammonium acetate (NH4 Ac, 4.5 mmol/kg). Results showed that Mrp2 function markedly increased in cortex and hippocampus of rats at 6 h following NH4 Ac administration. Significant increase in function of P-gp was observed in hippocampus of rats. Meanwhile, such alterations were in line with the increase in mRNA and protein levels of P-gp and Mrp2. Significant increase in levels of nuclear amount of nuclear factor-κB (NF-κB) p65 was also observed. Primarily cultured rat brain microvessel endothelial cells (rBMECs) were used for in vitro study. Data indicated that 24 h exposure to ammonia significantly increased function and expression of P-gp and Mrp2 in rBMECs, accompanied with activation of NF-κB. Furthermore, such alterations induced by ammonia were reversed by NF-κB inhibitor. In conclusion, this study demonstrates that hyperammonemia increases the function and expression of P-gp and Mrp2 at the BBB via activating NF-κB pathway. Hyperammonemia, a proverbial main factor responsible for neurocognitive disorder and blood-brain barrier (BBB) dysfunction resulting from liver failure, could increase the expression and activity of P-glycoprotein and multidrug resistance-associated protein 2 (Mrp2) at the BBB both in vivo and in vitro. Furthermore, the NF-κB activation stimulated by hyperammonemia may be the potential mechanism underlying such abnormalities induced by hyperammonemia.
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Affiliation(s)
- Ji Zhang
- Center of Drug Metabolism and Pharmacokinetics, China Pharmaceutical University, Nanjing, China
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Feldman B, Tuchman M, Caldovic L. A zebrafish model of hyperammonemia. Mol Genet Metab 2014; 113:142-7. [PMID: 25069822 PMCID: PMC4191821 DOI: 10.1016/j.ymgme.2014.07.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 07/01/2014] [Accepted: 07/01/2014] [Indexed: 02/08/2023]
Abstract
Hyperammonemia is the principal consequence of urea cycle defects and liver failure, and the exposure of the brain to elevated ammonia concentrations leads to a wide range of neuro-cognitive deficits, intellectual disabilities, coma and death. Current treatments focus almost exclusively on either reducing ammonia levels through the activation of alternative pathways for ammonia disposal or on liver transplantation. Ammonia is toxic to most fish and its pathophysiology appears to be similar to that in mammals. Since hyperammonemia can be induced in fish simply by immersing them in water with elevated concentration of ammonia, we sought to develop a zebrafish (Danio rerio) model of hyperammonemia. When exposed to 3mM ammonium acetate (NH4Ac), 50% of 4-day old (dpf) fish died within 3hours and 4mM NH4Ac was 100% lethal. We used 4dpf zebrafish exposed to 4mM NH4Ac to test whether the glutamine synthetase inhibitor methionine sulfoximine (MSO) and/or NMDA receptor antagonists MK-801, memantine and ketamine, which are known to protect the mammalian brain from hyperammonemia, prolong survival of hyperammonemic fish. MSO, MK-801, memantine and ketamine all prolonged the lives of the ammonia-treated fish. Treatment with the combination of MSO and an NMDA receptor antagonist was more effective than either drug alone. These results suggest that zebrafish can be used to screen for ammonia-neuroprotective agents. If successful, drugs that are discovered in this screen could complement current treatment approaches to improve the outcome of patients with hyperammonemia.
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Affiliation(s)
- B Feldman
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD, USA
| | - M Tuchman
- Children's National Medical Center, Washington DC, USA
| | - L Caldovic
- Children's National Medical Center, Washington DC, USA.
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Jayakumar AR, Tong XY, Curtis KM, Ruiz-Cordero R, Abreu MT, Norenberg MD. Increased toll-like receptor 4 in cerebral endothelial cells contributes to the astrocyte swelling and brain edema in acute hepatic encephalopathy. J Neurochem 2014; 128:890-903. [PMID: 24261962 PMCID: PMC3951576 DOI: 10.1111/jnc.12516] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Revised: 09/10/2013] [Accepted: 10/17/2013] [Indexed: 12/14/2022]
Abstract
Astrocyte swelling and the subsequent increase in intracranial pressure and brain herniation are major clinical consequences in patients with acute hepatic encephalopathy. We recently reported that conditioned media from brain endothelial cells (ECs) exposed to ammonia, a mixture of cytokines (CKs) or lipopolysaccharide (LPS), when added to astrocytes caused cell swelling. In this study, we investigated the possibility that ammonia and inflammatory agents activate the toll-like receptor 4 (TLR4) in ECs, resulting in the release of factors that ultimately cause astrocyte swelling. We found a significant increase in TLR4 protein expression when ECs were exposed to ammonia, CKs or LPS alone, while exposure of ECs to a combination of these agents potentiate such effects. In addition, astrocytes exposed to conditioned media from TLR4-silenced ECs that were treated with ammonia, CKs or LPS, resulted in a significant reduction in astrocyte swelling. TLR4 protein up-regulation was also detected in rat brain ECs after treatment with the liver toxin thioacetamide, and that thioacetamide-treated TLR4 knock-out mice exhibited a reduction in brain edema. These studies strongly suggest that ECs significantly contribute to the astrocyte swelling/brain edema in acute hepatic encephalopathy, likely as a consequence of increased TLR4 protein expression by blood-borne noxious agents.
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Affiliation(s)
- Arumugam R Jayakumar
- Laboratory of Neuropathology, Veterans Affairs Medical Center, Miami, Florida, USA; Department of Pathology, University of Miami Miller School of Medicine, Miami, Florida, USA
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Pizzurro DM, Dao K, Costa LG. Diazinon and diazoxon impair the ability of astrocytes to foster neurite outgrowth in primary hippocampal neurons. Toxicol Appl Pharmacol 2014; 274:372-82. [PMID: 24342266 PMCID: PMC3916905 DOI: 10.1016/j.taap.2013.11.023] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Revised: 11/26/2013] [Accepted: 11/29/2013] [Indexed: 11/25/2022]
Abstract
Evidence from in vivo and epidemiological studies suggests that organophosphorus insecticides (OPs) are developmental neurotoxicants, but possible underlying mechanisms are still unclear. Astrocytes are increasingly recognized for their active role in normal neuronal development. This study sought to investigate whether the widely-used OP diazinon (DZ), and its oxygen metabolite diazoxon (DZO), would affect glial-neuronal interactions as a potential mechanism of developmental neurotoxicity. Specifically, we investigated the effects of DZ and DZO on the ability of astrocytes to foster neurite outgrowth in primary hippocampal neurons. The results show that both DZ and DZO adversely affect astrocyte function, resulting in inhibited neurite outgrowth in hippocampal neurons. This effect appears to be mediated by oxidative stress, as indicated by OP-induced increased reactive oxygen species production in astrocytes and prevention of neurite outgrowth inhibition by antioxidants. The concentrations of OPs were devoid of cytotoxicity, and cause limited acetylcholinesterase inhibition in astrocytes (18 and 25% for DZ and DZO, respectively). Among astrocytic neuritogenic factors, the most important one is the extracellular matrix protein fibronectin. DZ and DZO decreased levels of fibronectin in astrocytes, and this effect was also attenuated by antioxidants. Underscoring the importance of fibronectin in this context, adding exogenous fibronectin to the co-culture system successfully prevented inhibition of neurite outgrowth caused by DZ and DZO. These results indicate that DZ and DZO increase oxidative stress in astrocytes, and this in turn modulates astrocytic fibronectin, leading to impaired neurite outgrowth in hippocampal neurons.
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Affiliation(s)
- Daniella M. Pizzurro
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Khoi Dao
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
| | - Lucio G. Costa
- Department of Environmental and Occupational Health Sciences, University of Washington, Seattle, WA, USA
- Department of Neuroscience, University of Parma, Parma, Italy
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Roles of changes in active glutamine transport in brain edema development during hepatic encephalopathy: an emerging concept. Neurochem Res 2013; 39:599-604. [PMID: 24072671 PMCID: PMC3926979 DOI: 10.1007/s11064-013-1141-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2013] [Revised: 08/20/2013] [Accepted: 08/22/2013] [Indexed: 12/12/2022]
Abstract
Excessive glutamine (Gln) synthesis in ammonia-overloaded astrocytes contributes to astrocytic swelling and brain edema, the major complication of hepatic encephalopathy (HE). Much of the newly formed Gln is believed to enter mitochondria, where it is recycled to ammonia, which causes mitochondrial dysfunction (a “Trojan horse” mode of action). A portion of Gln may increase osmotic pressure in astrocytes and the interstitial space, directly and independently contributing to brain tissue swelling. Here we discuss the possibility that altered functioning of Gln transport proteins located in the cellular or mitochondrial membranes, modulates the effects of increased Gln synthesis. Accumulation of excess Gln in mitochondria involves a carrier-mediated transport which is activated by ammonia. Studies on the expression of the cell membrane N-system transporters SN1 (SNAT3) and SN2 (SNAT5), which mediate Gln efflux from astrocytes rendered HE model-dependent effects. HE lowered the expression of SN1 at the RNA and protein level in the cerebral cortex (cc) in the thioacetamide (TAA) model of HE and the effect paralleled induction of cerebral cortical edema. Neither SN1 nor SN2 expression was affected by simple hyperammonemia, which produces no cc edema. TAA-induced HE is also associated with decreased expression of mRNA coding for the system A carriers SAT1 and SAT2, which stimulate Gln influx to neurons. Taken together, changes in the expression of Gln transporters during HE appear to favor retention of Gln in astrocytes and/or the interstitial space of the brain. HE may also affect arginine (Arg)/Gln exchange across the astrocytic cell membrane due to changes in the expression of the hybrid Arg/Gln transporter y+LAT2. Gln export from brain across the blood–brain barrier may be stimulated by HE via its increased exchange with peripheral tryptophan.
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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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Shaik IH, Miah MK, Bickel U, Mehvar R. Effects of short-term portacaval anastomosis on the peripheral and brain disposition of the blood-brain barrier permeability marker sodium fluorescein in rats. Brain Res 2013; 1531:84-93. [PMID: 23916670 DOI: 10.1016/j.brainres.2013.07.040] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 07/19/2013] [Accepted: 07/24/2013] [Indexed: 01/26/2023]
Abstract
Contradictory results have been reported with regard to the effects of various models of hepatic encephalopathy on the blood-brain barrier (BBB) permeability, which may be due partly to the use of brain concentrations of BBB markers without attention to their peripheral pharmacokinetics. The purpose of the current study was to investigate the effects of short-term portacaval anastomosis (PCA), a type B model of hepatic encephalopathy, on the peripheral pharmacokinetics and brain distribution of sodium fluorescein (FL), which is a small molecule marker of BBB passive permeability. A single 25mg/kg dose of FL was administered intravenously to 10-day PCA and sham-operated rats, and serial blood and bile (0-30min) and terminal (30min) brain samples were collected, and the concentrations of FL and its glucuronidated metabolite (FL-Glu) were measured by HPLC. Additionally, the free fractions of FL (fu) in all the plasma samples were determined, and the effects of bile salts on fu were investigated in vitro. Passive permeability of BBB to FL was estimated by brain uptake clearance (Kin) based on both the brain concentrations of FL and plasma concentrations of free (unbound) FL. PCA caused a 26% increase in the fu of FL in plasma, which was due to competition of bile acids with FL for binding to plasma proteins. Additionally, PCA reduced the biliary excretion of FL-Glu by 55%. However, free Kin values (µl/min/g brain) for the sham (0.265±0.034) and PCA (0.228±0.038) rats were not significantly different. It is concluded that whereas 10-day PCA alters the peripheral pharmacokinetics of FL, it does not significantly affect the BBB permeability to the marker.
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Affiliation(s)
- Imam H Shaik
- Department of Pharmaceutical Sciences and Center for Blood-Brain Barrier Research, School of Pharmacy, Texas Tech University Health Sciences Center, 1300 Coulter, Amarillo, TX 79106, USA
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Sturza A, Leisegang MS, Babelova A, Schröder K, Benkhoff S, Loot AE, Fleming I, Schulz R, Muntean DM, Brandes RP. Monoamine Oxidases Are Mediators of Endothelial Dysfunction in the Mouse Aorta. Hypertension 2013; 62:140-6. [DOI: 10.1161/hypertensionaha.113.01314] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
Monoamine oxidases (MAOs) generate H
2
O
2
as a by-product of their catalytic cycle. Whether MAOs are mediators of endothelial dysfunction is unknown and was determined here in the angiotensin II and lipopolysaccharide-models of vascular dysfunction in mice. Quantitative real-time polymerase chain reaction revealed that mouse aortas contain enzymes involved in catecholamine generation and MAO-A and MAO-B mRNA. MAO-A and -B proteins could be detected by Western blot not only in mouse aortas but also in human umbilical vein endothelial cells. Ex vivo incubation of mouse aorta with recombinant MAO-A increased H
2
O
2
formation and induced endothelial dysfunction that was attenuated by polyethylene glycol-catalase and MAO inhibitors. In vivo lipopolysaccharide (8 mg/kg IP overnight) or angiotensin II (1 mg/kg per day, 2 weeks, minipump) treatment induced vascular MAO-A and -B expressions and resulted in attenuated endothelium-dependent relaxation of the aorta in response to acetylcholine. MAO inhibitors reduced the lipopolysaccharide- and angiotensin II–induced aortic reactive oxygen species formation by 50% (ferrous oxidation xylenol orange assay) and partially normalized endothelium-dependent relaxation. MAO-A and MAO-B inhibitors had an additive effect; combined application completely restored endothelium-dependent relaxation. To determine how MAO-dependent H
2
O
2
formation induces endothelial dysfunction, cyclic GMP was measured. Histamine stimulation of human umbilical vein endothelial cells to activate endothelial NO synthase resulted in an increase in cyclic GMP, which was almost abrogated by MAO-A exposure. MAO inhibition prevented this effect, suggesting that MAO-induced H
2
O
2
formation is sufficient to attenuate endothelial NO release. Thus, MAO-A and MAO-B are both expressed in the mouse aorta, induced by in vivo lipopolysaccharide and angiotensin II treatment and contribute via the generation of H
2
O
2
to endothelial dysfunction in vascular disease models.
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Affiliation(s)
- Adrian Sturza
- From the Institut für Kardiovaskuläre Physiologie (A.S., M.S.L., A.B., K.S., S.B., R.P.B.) and Institute for Vascular Signaling (A.E.L., I.F.), Goethe-Universität, Frankfurt, Germany; Department of Pathophysiology, “Victor Babes” University of Medicine and Pharmacy, Timisoara, Romania (A.S., D.M.M.); Institute of Physiology, Justus-Liebig University, Giessen, Germany (R.S.); and DZHK (German Centre for Cardiovascular Research), partner site Rhine-Main, Germany (A.S., M.S.L., A.B., K.S., S.B., A.E.L
| | - Matthias S. Leisegang
- From the Institut für Kardiovaskuläre Physiologie (A.S., M.S.L., A.B., K.S., S.B., R.P.B.) and Institute for Vascular Signaling (A.E.L., I.F.), Goethe-Universität, Frankfurt, Germany; Department of Pathophysiology, “Victor Babes” University of Medicine and Pharmacy, Timisoara, Romania (A.S., D.M.M.); Institute of Physiology, Justus-Liebig University, Giessen, Germany (R.S.); and DZHK (German Centre for Cardiovascular Research), partner site Rhine-Main, Germany (A.S., M.S.L., A.B., K.S., S.B., A.E.L
| | - Andrea Babelova
- From the Institut für Kardiovaskuläre Physiologie (A.S., M.S.L., A.B., K.S., S.B., R.P.B.) and Institute for Vascular Signaling (A.E.L., I.F.), Goethe-Universität, Frankfurt, Germany; Department of Pathophysiology, “Victor Babes” University of Medicine and Pharmacy, Timisoara, Romania (A.S., D.M.M.); Institute of Physiology, Justus-Liebig University, Giessen, Germany (R.S.); and DZHK (German Centre for Cardiovascular Research), partner site Rhine-Main, Germany (A.S., M.S.L., A.B., K.S., S.B., A.E.L
| | - Katrin Schröder
- From the Institut für Kardiovaskuläre Physiologie (A.S., M.S.L., A.B., K.S., S.B., R.P.B.) and Institute for Vascular Signaling (A.E.L., I.F.), Goethe-Universität, Frankfurt, Germany; Department of Pathophysiology, “Victor Babes” University of Medicine and Pharmacy, Timisoara, Romania (A.S., D.M.M.); Institute of Physiology, Justus-Liebig University, Giessen, Germany (R.S.); and DZHK (German Centre for Cardiovascular Research), partner site Rhine-Main, Germany (A.S., M.S.L., A.B., K.S., S.B., A.E.L
| | - Sebastian Benkhoff
- From the Institut für Kardiovaskuläre Physiologie (A.S., M.S.L., A.B., K.S., S.B., R.P.B.) and Institute for Vascular Signaling (A.E.L., I.F.), Goethe-Universität, Frankfurt, Germany; Department of Pathophysiology, “Victor Babes” University of Medicine and Pharmacy, Timisoara, Romania (A.S., D.M.M.); Institute of Physiology, Justus-Liebig University, Giessen, Germany (R.S.); and DZHK (German Centre for Cardiovascular Research), partner site Rhine-Main, Germany (A.S., M.S.L., A.B., K.S., S.B., A.E.L
| | - Annemarieke E. Loot
- From the Institut für Kardiovaskuläre Physiologie (A.S., M.S.L., A.B., K.S., S.B., R.P.B.) and Institute for Vascular Signaling (A.E.L., I.F.), Goethe-Universität, Frankfurt, Germany; Department of Pathophysiology, “Victor Babes” University of Medicine and Pharmacy, Timisoara, Romania (A.S., D.M.M.); Institute of Physiology, Justus-Liebig University, Giessen, Germany (R.S.); and DZHK (German Centre for Cardiovascular Research), partner site Rhine-Main, Germany (A.S., M.S.L., A.B., K.S., S.B., A.E.L
| | - Ingrid Fleming
- From the Institut für Kardiovaskuläre Physiologie (A.S., M.S.L., A.B., K.S., S.B., R.P.B.) and Institute for Vascular Signaling (A.E.L., I.F.), Goethe-Universität, Frankfurt, Germany; Department of Pathophysiology, “Victor Babes” University of Medicine and Pharmacy, Timisoara, Romania (A.S., D.M.M.); Institute of Physiology, Justus-Liebig University, Giessen, Germany (R.S.); and DZHK (German Centre for Cardiovascular Research), partner site Rhine-Main, Germany (A.S., M.S.L., A.B., K.S., S.B., A.E.L
| | - Rainer Schulz
- From the Institut für Kardiovaskuläre Physiologie (A.S., M.S.L., A.B., K.S., S.B., R.P.B.) and Institute for Vascular Signaling (A.E.L., I.F.), Goethe-Universität, Frankfurt, Germany; Department of Pathophysiology, “Victor Babes” University of Medicine and Pharmacy, Timisoara, Romania (A.S., D.M.M.); Institute of Physiology, Justus-Liebig University, Giessen, Germany (R.S.); and DZHK (German Centre for Cardiovascular Research), partner site Rhine-Main, Germany (A.S., M.S.L., A.B., K.S., S.B., A.E.L
| | - Danina M. Muntean
- From the Institut für Kardiovaskuläre Physiologie (A.S., M.S.L., A.B., K.S., S.B., R.P.B.) and Institute for Vascular Signaling (A.E.L., I.F.), Goethe-Universität, Frankfurt, Germany; Department of Pathophysiology, “Victor Babes” University of Medicine and Pharmacy, Timisoara, Romania (A.S., D.M.M.); Institute of Physiology, Justus-Liebig University, Giessen, Germany (R.S.); and DZHK (German Centre for Cardiovascular Research), partner site Rhine-Main, Germany (A.S., M.S.L., A.B., K.S., S.B., A.E.L
| | - Ralf P. Brandes
- From the Institut für Kardiovaskuläre Physiologie (A.S., M.S.L., A.B., K.S., S.B., R.P.B.) and Institute for Vascular Signaling (A.E.L., I.F.), Goethe-Universität, Frankfurt, Germany; Department of Pathophysiology, “Victor Babes” University of Medicine and Pharmacy, Timisoara, Romania (A.S., D.M.M.); Institute of Physiology, Justus-Liebig University, Giessen, Germany (R.S.); and DZHK (German Centre for Cardiovascular Research), partner site Rhine-Main, Germany (A.S., M.S.L., A.B., K.S., S.B., A.E.L
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Braissant O, McLin VA, Cudalbu C. Ammonia toxicity to the brain. J Inherit Metab Dis 2013; 36:595-612. [PMID: 23109059 DOI: 10.1007/s10545-012-9546-2] [Citation(s) in RCA: 183] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 09/19/2012] [Accepted: 09/25/2012] [Indexed: 12/21/2022]
Abstract
Hyperammonemia can be caused by various acquired or inherited disorders such as urea cycle defects. The brain is much more susceptible to the deleterious effects of ammonium in childhood than in adulthood. Hyperammonemia provokes irreversible damage to the developing central nervous system: cortical atrophy, ventricular enlargement and demyelination lead to cognitive impairment, seizures and cerebral palsy. The mechanisms leading to these severe brain lesions are still not well understood, but recent studies show that ammonium exposure alters several amino acid pathways and neurotransmitter systems, cerebral energy metabolism, nitric oxide synthesis, oxidative stress and signal transduction pathways. All in all, at the cellular level, these are associated with alterations in neuronal differentiation and patterns of cell death. Recent advances in imaging techniques are increasing our understanding of these processes through detailed in vivo longitudinal analysis of neurobiochemical changes associated with hyperammonemia. Further, several potential neuroprotective strategies have been put forward recently, including the use of NMDA receptor antagonists, nitric oxide inhibitors, creatine, acetyl-L-carnitine, CNTF or inhibitors of MAPKs and glutamine synthetase. Magnetic resonance imaging and spectroscopy will ultimately be a powerful tool to measure the effects of these neuroprotective approaches.
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Affiliation(s)
- Olivier Braissant
- Service of Biomedicine, Lausanne University Hospital, Avenue Pierre-Decker 2, CI 02/33, CH-1011 Lausanne, Switzerland.
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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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42
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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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43
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Bosoi CR, Rose CF. Brain edema in acute liver failure and chronic liver disease: similarities and differences. Neurochem Int 2013; 62:446-57. [PMID: 23376027 DOI: 10.1016/j.neuint.2013.01.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 01/11/2013] [Accepted: 01/16/2013] [Indexed: 12/12/2022]
Abstract
Hepatic encephalopathy (HE) is a complex neuropsychiatric syndrome that typically develops as a result of acute liver failure or chronic liver disease. Brain edema is a common feature associated with HE. In acute liver failure, brain edema contributes to an increase in intracranial pressure, which can fatally lead to brain stem herniation. In chronic liver disease, intracranial hypertension is rarely observed, even though brain edema may be present. This discrepancy in the development of intracranial hypertension in acute liver failure versus chronic liver disease suggests that brain edema plays a different role in relation to the onset of HE. Furthermore, the pathophysiological mechanisms involved in the development of brain edema in acute liver failure and chronic liver disease are dissimilar. This review explores the types of brain edema, the cells, and pathogenic factors involved in its development, while emphasizing the differences in acute liver failure versus chronic liver disease. The implications of brain edema developing as a neuropathological consequence of HE, or as a cause of HE, are also discussed.
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Affiliation(s)
- Cristina R Bosoi
- Neuroscience Research Unit, Hôpital Saint-Luc (CRCHUM), Université de Montréal, Québec, Canada
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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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Skowrońska M, Albrecht J. Oxidative and nitrosative stress in ammonia neurotoxicity. Neurochem Int 2012; 62:731-7. [PMID: 23142151 DOI: 10.1016/j.neuint.2012.10.013] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2012] [Revised: 10/18/2012] [Accepted: 10/28/2012] [Indexed: 12/16/2022]
Abstract
Increased ammonia accumulation in the brain due to liver dysfunction is a major contributor to the pathogenesis of hepatic encephalopathy (HE). Fatal outcome of rapidly progressing (acute) HE is mainly related to cytotoxic brain edema associated with astrocytic swelling. An increase of brain ammonia in experimental animals or treatment of cultured astrocytes with ammonia generates reactive oxygen and nitrogen species in the target tissues, leading to oxidative/nitrosative stress (ONS). In cultured astrocytes, ammonia-induced ONS is invariably associated with the increase of the astrocytic cell volume. Interrelated mechanisms underlying this response include increased nitric oxide (NO) synthesis which is partly coupled to the activation of NMDA receptors and increased generation of reactive oxygen species by NADPH oxidase. ONS and astrocytic swelling are further augmented by excessive synthesis of glutamine (Gln) which impairs mitochondrial function following its accumulation in there and degradation back to ammonia ("the Trojan horse" hypothesis). Ammonia also induces ONS in other cell types of the CNS: neurons, microglia and the brain capillary endothelial cells (BCEC). ONS in microglia contributes to the central inflammatory response, while its metabolic and pathophysiological consequences in the BCEC evolve to the vasogenic brain edema associated with HE. Ammonia-induced ONS results in the oxidation of mRNA and nitration/nitrosylation of proteins which impact intracellular metabolism and potentiate the neurotoxic effects. Simultaneously, ammonia facilitates the antioxidant response of the brain, by activating astrocytic transport and export of glutathione, in this way increasing the availability of precursors of neuronal glutathione synthesis.
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Affiliation(s)
- Marta Skowrońska
- Department of Neurotoxicology, Mossakowski Medical Research Center, Polish Academy of Sciences, Pawinskiego 5, 02-106 Warsaw, Poland.
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Jayakumar AR, Tong XY, Ospel J, Norenberg MD. Role of cerebral endothelial cells in the astrocyte swelling and brain edema associated with acute hepatic encephalopathy. Neuroscience 2012; 218:305-16. [PMID: 22609932 PMCID: PMC4714767 DOI: 10.1016/j.neuroscience.2012.05.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Revised: 04/25/2012] [Accepted: 05/03/2012] [Indexed: 12/15/2022]
Abstract
Brain edema is an important complication of acute hepatic encephalopathy (AHE), and astrocyte swelling is largely responsible for its development. Elevated blood and brain ammonia levels have been considered as major etiological factors in this edema. In addition to ammonia, recent studies have suggested that systemic infection, inflammation (and associated cytokines (CKs)), as well as endotoxin (lipopolysaccharide (LPS)) are also involved in AHE-associated brain edema. As endothelial cells (ECs) are the first resident brain cells exposed to blood-borne "noxious agents" (i.e., ammonia, CKs, LPS) that are present in AHE, these cells may be in a critical position to react to these agents and trigger a process resulting in astrocyte swelling/brain edema. We therefore examined the effect of conditioned media (CM) from ammonia, LPS and cytokine-treated cultured brain ECs on cell swelling in cultured astrocytes. CM from ammonia-treated ECs when added to astrocytes caused significant cell swelling, and such swelling was potentiated when astrocytes were exposed to CM from ECs treated with a combination of ammonia, LPS and CKs. We also found an additive effect when astrocytes were exposed to ammonia along with CM from ammonia-treated ECs. Additionally, ECs treated with ammonia showed a significant increase in the production of oxy-radicals, nitric oxide (NO), as well as evidence of oxidative/nitrative stress and activation of the transcription factor nuclear factor kappa B (NF-κB). CM derived from ECs treated with ammonia, along with antioxidants (AOs) or the NF-κB inhibitor BAY 11-7082, when added to astrocytes resulted in a significant reduction in cell swelling, as compared to the effect of CM from ECs-treated only with ammonia. We also identified increased nuclear NF-κB expression in rat brain cortical ECs in the thioacetamide (TAA) model of AHE. These studies suggest that ECs significantly contribute to the astrocyte swelling/brain edema in AHE, likely as a consequence of oxidative/nitrative stress and activation of NF-κB.
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Affiliation(s)
- A R Jayakumar
- South Florida Foundation for Research & Education Inc., Veterans Affairs Medical Center, Miami, FL, USA
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