1
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Wang JY, Hsu HY, Liu ST, Lin CH. Ammonia exposure impairs bone mineralization in zebrafish (Danio rerio) larvae. Comp Biochem Physiol C Toxicol Pharmacol 2024; 287:110040. [PMID: 39265966 DOI: 10.1016/j.cbpc.2024.110040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2024] [Revised: 08/17/2024] [Accepted: 09/08/2024] [Indexed: 09/14/2024]
Abstract
Ammonia is a major pollutant of freshwater environments. Previous studies have indicated that ammonia exposure adversely affects the physiology of freshwater fish. However, its effect on bone mineralization in freshwater fish larvae remains unclear. In this study, zebrafish larvae were used as a model to investigate the effects of different ammonia levels (0, 2.5, 5, and 10 mM NH4Cl) on the survival rate, body length, and bone mineralization of fish. The survival rate of zebrafish embryos exposed to different NH4Cl concentrations for 8 days was not affected. In contrast, the body length and bone mineralization of zebrafish larvae at 8 days post fertilization (dpf) were significantly reduced at 5 and 10 mM NH4Cl exposure. Further investigations revealed that ammonia exposure decreased the mRNA expression of osteoblast-related genes and increased that of osteoclast-related genes. Additionally, exposure to 5 mM and 10 mM NH4Cl induced the production of reactive oxygen species (ROS). 10 mM-but not 5 mM-NH4Cl exposure reduced the calcium and phosphorus content in 8 dpf zebrafish larvae. In conclusion, ammonia exposure induces bone resorption, while decreasing the calcium and phosphorus content of the whole body and bone formation, resulting in impaired bone mineralization in fish larvae.
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Affiliation(s)
- Jun-Yi Wang
- Department of Marine Biotechnology, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
| | - Hsuan-Yi Hsu
- Department of Marine Biotechnology, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan
| | - Sian-Tai Liu
- Department of Life Science, National Taiwan University, Taipei, Taiwan
| | - Chia-Hao Lin
- Department of Marine Biotechnology, National Kaohsiung University of Science and Technology, Kaohsiung, Taiwan; The iEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung, Taiwan.
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2
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Prasad SK, Acharjee A, Singh VV, Trigun SK, Acharjee P. Modulation of brain energy metabolism in hepatic encephalopathy: impact of glucose metabolic dysfunction. Metab Brain Dis 2024:10.1007/s11011-024-01407-7. [PMID: 39120853 DOI: 10.1007/s11011-024-01407-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2024] [Accepted: 08/05/2024] [Indexed: 08/10/2024]
Abstract
Cerebral function is linked to a high level of metabolic activity and relies on glucose as its primary energy source. Glucose aids in the maintenance of physiological brain activities; as a result, a disruption in metabolism has a significant impact on brain function, launching a chain of events that leads to neuronal death. This metabolic insufficiency has been observed in a variety of brain diseases and neuroexcitotoxicity disorders, including hepatic encephalopathy. It is a significant neurological complication that develops in people with liver disease, ranging from asymptomatic abnormalities to coma. Hyperammonemia is the main neurotoxic villain in the development of hepatic encephalopathy and induces a wide range of complications in the brain. The neurotoxic effects of ammonia on brain function are thought to be mediated by impaired glucose metabolism. Accordingly, in this review, we provide an understanding of deranged brain energy metabolism, emphasizing the role of glucose metabolic dysfunction in the pathogenesis of hepatic encephalopathy. We also highlighted the differential metabolic profiles of brain cells and the status of metabolic cooperation between them. The major metabolic pathways that have been explored are glycolysis, glycogen metabolism, lactate metabolism, the pentose phosphate pathway, and the Krebs cycle. Furthermore, the lack of efficacy in current hepatic encephalopathy treatment methods highlights the need to investigate potential therapeutic targets for hepatic encephalopathy, with regulating deficient bioenergetics being a viable alternative in this case. This review also demonstrates the importance of the development of glucose metabolism-focused disease diagnostics and treatments, which are now being pursued for many ailments.
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Affiliation(s)
- Shambhu Kumar Prasad
- Biochemistry and Molecular Biology Unit, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi, 221005, India
| | - Arup Acharjee
- Department of Zoology, University of Allahabad, Prayagraj, 211002, India.
| | - Vishal Vikram Singh
- Biochemistry and Molecular Biology Unit, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi, 221005, India
| | - Surendra Kumar Trigun
- Biochemistry and Molecular Biology Unit, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi, 221005, India
| | - Papia Acharjee
- Biochemistry and Molecular Biology Unit, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi, 221005, India.
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3
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Seidl MJ, Scharre S, Posset R, Druck AC, Epp F, Okun JG, Dimitrov B, Hoffmann GF, Kölker S, Zielonka M. ASS1 deficiency is associated with impaired neuronal differentiation in zebrafish larvae. Mol Genet Metab 2024; 141:108097. [PMID: 38113552 DOI: 10.1016/j.ymgme.2023.108097] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 11/22/2023] [Accepted: 11/23/2023] [Indexed: 12/21/2023]
Abstract
Citrullinemia type 1 (CTLN1) is a rare autosomal recessive urea cycle disorder caused by deficiency of the cytosolic enzyme argininosuccinate synthetase 1 (ASS1) due to pathogenic variants in the ASS1 gene located on chromosome 9q34.11. Even though hyperammenomia is considered the major pathomechanistic factor for neurological impairment and cognitive dysfunction, a relevant subset of individuals presents with a neurodegenerative course in the absence of hyperammonemic decompensations. Here we show, that ASS1 deficiency induced by antisense-mediated knockdown of the zebrafish ASS1 homologue is associated with defective neuronal differentiation ultimately causing neuronal cell loss and consecutively decreased brain size in zebrafish larvae in vivo. Whereas ASS1-deficient zebrafish larvae are characterized by markedly elevated concentrations of citrulline - the biochemical hallmark of CTLN1, accumulation of L-citrulline, hyperammonemia or therewith associated secondary metabolic alterations did not account for the observed phenotype. Intriguingly, coinjection of the human ASS1 mRNA not only normalized citrulline concentration but also reversed the morphological cerebral phenotype and restored brain size, confirming conserved functional properties of ASS1 across species. The results of the present study imply a novel, potentially non-enzymatic (moonlighting) function of the ASS1 protein in neurodevelopment.
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Affiliation(s)
- Marie J Seidl
- Heidelberg University, Medical Faculty Heidelberg, and Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Svenja Scharre
- Heidelberg University, Medical Faculty Heidelberg, and Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Roland Posset
- Heidelberg University, Medical Faculty Heidelberg, and Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Ann-Catrin Druck
- Heidelberg University, Medical Faculty Heidelberg, and Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Friederike Epp
- Heidelberg University, Medical Faculty Heidelberg, and Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Jürgen G Okun
- Heidelberg University, Medical Faculty Heidelberg, and Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Bianca Dimitrov
- Heidelberg University, Medical Faculty Heidelberg, and Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Georg F Hoffmann
- Heidelberg University, Medical Faculty Heidelberg, and Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Stefan Kölker
- Heidelberg University, Medical Faculty Heidelberg, and Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Matthias Zielonka
- Heidelberg University, Medical Faculty Heidelberg, and Division of Pediatric Neurology and Metabolic Medicine, Center for Child and Adolescent Medicine, University Hospital Heidelberg, Heidelberg, Germany; Heidelberg Research Center for Molecular Medicine (HRCMM), Heidelberg, Germany.
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4
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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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5
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Mishra S, Welch N, Karthikeyan M, Bellar A, Musich R, Singh SS, Zhang D, Sekar J, Attaway A, Chelluboyina AK, Lorkowski SW, Roychowdhury S, Li L, Willard B, Smith JD, Hoppel C, Vachharajani V, Kumar A, Dasarathy S. Dysregulated cellular redox status during hyperammonemia causes mitochondrial dysfunction and senescence by inhibiting sirtuin-mediated deacetylation. Aging Cell 2023; 22:e13852. [PMID: 37101412 PMCID: PMC10352558 DOI: 10.1111/acel.13852] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 03/29/2023] [Accepted: 03/31/2023] [Indexed: 04/28/2023] Open
Abstract
Perturbed metabolism of ammonia, an endogenous cytotoxin, causes mitochondrial dysfunction, reduced NAD+ /NADH (redox) ratio, and postmitotic senescence. Sirtuins are NAD+ -dependent deacetylases that delay senescence. In multiomics analyses, NAD metabolism and sirtuin pathways are enriched during hyperammonemia. Consistently, NAD+ -dependent Sirtuin3 (Sirt3) expression and deacetylase activity were decreased, and protein acetylation was increased in human and murine skeletal muscle/myotubes. Global acetylomics and subcellular fractions from myotubes showed hyperammonemia-induced hyperacetylation of cellular signaling and mitochondrial proteins. We dissected the mechanisms and consequences of hyperammonemia-induced NAD metabolism by complementary genetic and chemical approaches. Hyperammonemia inhibited electron transport chain components, specifically complex I that oxidizes NADH to NAD+ , that resulted in lower redox ratio. Ammonia also caused mitochondrial oxidative dysfunction, lower mitochondrial NAD+ -sensor Sirt3, protein hyperacetylation, and postmitotic senescence. Mitochondrial-targeted Lactobacillus brevis NADH oxidase (MitoLbNOX), but not NAD+ precursor nicotinamide riboside, reversed ammonia-induced oxidative dysfunction, electron transport chain supercomplex disassembly, lower ATP and NAD+ content, protein hyperacetylation, Sirt3 dysfunction and postmitotic senescence in myotubes. Even though Sirt3 overexpression reversed ammonia-induced hyperacetylation, lower redox status or mitochondrial oxidative dysfunction were not reversed. These data show that acetylation is a consequence of, but is not the mechanism of, lower redox status or oxidative dysfunction during hyperammonemia. Targeting NADH oxidation is a potential approach to reverse and potentially prevent ammonia-induced postmitotic senescence in skeletal muscle. Since dysregulated ammonia metabolism occurs with aging, and NAD+ biosynthesis is reduced in sarcopenia, our studies provide a biochemical basis for cellular senescence and have relevance in multiple tissues.
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Affiliation(s)
- Saurabh Mishra
- Department of Inflammation and ImmunityLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Nicole Welch
- Department of Inflammation and ImmunityLerner Research Institute, Cleveland ClinicClevelandOhioUSA
- Departments of Gastroenterology and HepatologyCleveland ClinicClevelandOhioUSA
| | - Manikandan Karthikeyan
- Department of Inflammation and ImmunityLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Annette Bellar
- Department of Inflammation and ImmunityLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Ryan Musich
- Department of Inflammation and ImmunityLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Shashi Shekhar Singh
- Department of Inflammation and ImmunityLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Dongmei Zhang
- Proteomics and Metabolomics coreLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Jinendiran Sekar
- Department of Inflammation and ImmunityLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Amy H. Attaway
- Department of Inflammation and ImmunityLerner Research Institute, Cleveland ClinicClevelandOhioUSA
- Departments of Pulmonary MedicineCleveland ClinicClevelandOhioUSA
| | - Aruna Kumar Chelluboyina
- Department of Inflammation and ImmunityLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Shuhui Wang Lorkowski
- Cardiovascular and Metabolic SciencesLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Sanjoy Roychowdhury
- Department of Inflammation and ImmunityLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Ling Li
- Proteomics and Metabolomics coreLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Belinda Willard
- Proteomics and Metabolomics coreLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Jonathan D. Smith
- Cardiovascular and Metabolic SciencesLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Charles L. Hoppel
- Department of PharmacologyCase Western Reserve University School of MedicineClevelandOhioUSA
| | - Vidula Vachharajani
- Department of Inflammation and ImmunityLerner Research Institute, Cleveland ClinicClevelandOhioUSA
- Critical Care Medicine, Respiratory Institute, Cleveland ClinicClevelandOhioUSA
| | - Avinash Kumar
- Department of Inflammation and ImmunityLerner Research Institute, Cleveland ClinicClevelandOhioUSA
| | - Srinivasan Dasarathy
- Department of Inflammation and ImmunityLerner Research Institute, Cleveland ClinicClevelandOhioUSA
- Departments of Gastroenterology and HepatologyCleveland ClinicClevelandOhioUSA
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6
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Ramakrishna K, Sinku S, Majumdar S, Singh N, Gajendra TA, Rani A, Krishnamurthy S. Indole-3-carbinol ameliorated the thioacetamide-induced hepatic encephalopathy in rats. Toxicology 2023; 492:153542. [PMID: 37150287 DOI: 10.1016/j.tox.2023.153542] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 05/03/2023] [Accepted: 05/04/2023] [Indexed: 05/09/2023]
Abstract
Indole-3-carbinol (I3C) is reported to have hepatic and neuroprotective properties. However, the I3C role in the protection of the liver and brain in the pathological condition of hepatic encephalopathy has not been investigated. Therefore, in the present study, we have assessed the hepatic and neuroprotective roles of I3C against thioacetamide (TAA)- induced hepatic encephalopathy in Wistar rats. TAA (300mg/kg) was intraperitoneally administered to Wistar rats to induce hepatic encephalopathy. The elevated levels of ammonia in the blood, liver, and brain were substantially lowered by I3C treatment (25, 50, and 100mg/kg, oral, 7 days). I3C significantly ameliorated the TAA-induced liver dysfunction by decreasing the alanine transaminase, aspartate transaminase, and alkaline phosphatase enzymes and reduced the elevated cytochrome P4502E1 (CYP2E1) activity in the liver and brain. Further, I3C alleviated mitochondrial dysfunction and oxidative stress in the brain. I3C treatment improved the anti-inflammatory cytokine interleukin (IL)-10 while reducing inflammatory cytokines such as tumor necrosis factor-1 and IL-6 in hepatic encephalopathy rats. I3C reduced the levels of apoptotic indicators mediated by the mitochondria, including cytochrome c, caspase 9, and caspase 3. Concurrently, I3C mitigated the liver and brain histological abnormalities in hepatic encephalopathy rats. Therefore, the present study concluded that the I3C protected the liver and brain from TAA-induced hepatic encephalopathy injury by inhibiting CYP2E1 enzyme activity and decreasing ammonia, oxidative stress, inflammation, and apoptosis. The present study provides preclinical validation of I3C use as hepatic and neuroprotective for hepatic encephalopathy management.
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Affiliation(s)
- Kakarla Ramakrishna
- Department of Pharmaceutical Engineering and Technology, Indian Institute of Technology, Banaras Hindu University (IIT BHU), Varanasi, Uttar Pradesh, India; Department of Pharmacy, Koneru Lakshmaiah Education Foundation, Vaddeswaram, Andhra Pradesh, India
| | - Sangeetha Sinku
- Department of Pharmaceutical Engineering and Technology, Indian Institute of Technology, Banaras Hindu University (IIT BHU), Varanasi, Uttar Pradesh, India
| | - Shreyasi Majumdar
- Department of Pharmaceutical Engineering and Technology, Indian Institute of Technology, Banaras Hindu University (IIT BHU), Varanasi, Uttar Pradesh, India
| | - Neha Singh
- Department of Pharmaceutical Engineering and Technology, Indian Institute of Technology, Banaras Hindu University (IIT BHU), Varanasi, Uttar Pradesh, India
| | - T A Gajendra
- Department of Pharmaceutical Engineering and Technology, Indian Institute of Technology, Banaras Hindu University (IIT BHU), Varanasi, Uttar Pradesh, India
| | - Asha Rani
- Department of Pharmaceutical Engineering and Technology, Indian Institute of Technology, Banaras Hindu University (IIT BHU), Varanasi, Uttar Pradesh, India
| | - Sairam Krishnamurthy
- Department of Pharmaceutical Engineering and Technology, Indian Institute of Technology, Banaras Hindu University (IIT BHU), Varanasi, Uttar Pradesh, India.
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Nakadate K, Sono C, Mita H, Itakura Y, Kawakami K. Severe Acute Liver Dysfunction Induces Delayed Hepatocyte Swelling and Cytoplasmic Vacuolization, and Delayed Cortical Neuronal Cell Death. Int J Mol Sci 2023; 24:ijms24087351. [PMID: 37108515 PMCID: PMC10139143 DOI: 10.3390/ijms24087351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 04/10/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
Liver dysfunction is the main cause of hepatic encephalopathy. However, histopathological changes in the brain associated with hepatic encephalopathy remain unclear. Therefore, we investigated pathological changes in the liver and brain using an acute hepatic encephalopathy mouse model. After administering ammonium acetate, a transient increase in the blood ammonia level was observed, which returned to normal levels after 24 h. Consciousness and motor levels also returned to normal. It was revealed that hepatocyte swelling, and cytoplasmic vacuolization progressed over time in the liver tissue. Blood biochemistry also suggested hepatocyte dysfunction. In the brain, histopathological changes, such as perivascular astrocyte swelling, were observed 3 h after ammonium acetate administration. Abnormalities in neuronal organelles, especially mitochondria and rough endoplasmic reticulum, were also observed. Additionally, neuronal cell death was observed 24 h post-ammonia treatment when blood ammonia levels had returned to normal. Activation of reactive microglia and increased expression of inducible nitric oxide synthase (iNOS) were also observed seven days after a transient increase in blood ammonia. These results suggest that delayed neuronal atrophy could be iNOS-mediated cell death due to activation of reactive microglia. The findings also suggest that severe acute hepatic encephalopathy causes continued delayed brain cytotoxicity even after consciousness recovery.
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Affiliation(s)
- Kazuhiko Nakadate
- Department of Basic Science, Educational and Research Center for Pharmacy, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose 204-8588, Tokyo, Japan
| | - Chiaki Sono
- Department of Basic Science, Educational and Research Center for Pharmacy, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose 204-8588, Tokyo, Japan
| | - Homura Mita
- Department of Basic Science, Educational and Research Center for Pharmacy, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose 204-8588, Tokyo, Japan
| | - Yuki Itakura
- Department of Basic Science, Educational and Research Center for Pharmacy, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose 204-8588, Tokyo, Japan
| | - Kiyoharu Kawakami
- Department of Basic Science, Educational and Research Center for Pharmacy, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose 204-8588, Tokyo, Japan
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8
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Andersen JV, Schousboe A. Glial Glutamine Homeostasis in Health and Disease. Neurochem Res 2023; 48:1100-1128. [PMID: 36322369 DOI: 10.1007/s11064-022-03771-1] [Citation(s) in RCA: 23] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Revised: 08/25/2022] [Accepted: 09/27/2022] [Indexed: 11/05/2022]
Abstract
Glutamine is an essential cerebral metabolite. Several critical brain processes are directly linked to glutamine, including ammonia homeostasis, energy metabolism and neurotransmitter recycling. Astrocytes synthesize and release large quantities of glutamine, which is taken up by neurons to replenish the glutamate and GABA neurotransmitter pools. Astrocyte glutamine hereby sustains the glutamate/GABA-glutamine cycle, synaptic transmission and general brain function. Cerebral glutamine homeostasis is linked to the metabolic coupling of neurons and astrocytes, and relies on multiple cellular processes, including TCA cycle function, synaptic transmission and neurotransmitter uptake. Dysregulations of processes related to glutamine homeostasis are associated with several neurological diseases and may mediate excitotoxicity and neurodegeneration. In particular, diminished astrocyte glutamine synthesis is a common neuropathological component, depriving neurons of an essential metabolic substrate and precursor for neurotransmitter synthesis, hereby leading to synaptic dysfunction. While astrocyte glutamine synthesis is quantitatively dominant in the brain, oligodendrocyte-derived glutamine may serve important functions in white matter structures. In this review, the crucial roles of glial glutamine homeostasis in the healthy and diseased brain are discussed. First, we provide an overview of cellular recycling, transport, synthesis and metabolism of glutamine in the brain. These cellular aspects are subsequently discussed in relation to pathological glutamine homeostasis of hepatic encephalopathy, epilepsy, Alzheimer's disease, Huntington's disease and amyotrophic lateral sclerosis. Further studies on the multifaceted roles of cerebral glutamine will not only increase our understanding of the metabolic collaboration between brain cells, but may also aid to reveal much needed therapeutic targets of several neurological pathologies.
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Affiliation(s)
- Jens V Andersen
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
| | - Arne Schousboe
- Department of Drug Design and Pharmacology, University of Copenhagen, Copenhagen, Denmark.
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9
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Anamika, Roy A, Trigun SK. Hippocampus mitochondrial MnSOD activation by a SIRT3 activator, honokiol, correlates with its deacetylation and upregulation of FoxO3a and PGC1α in a rat model of ammonia neurotoxicity. J Cell Biochem 2023; 124:606-618. [PMID: 36922709 DOI: 10.1002/jcb.30393] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 02/13/2023] [Accepted: 02/15/2023] [Indexed: 03/18/2023]
Abstract
We have recently reported that honokiol (HKL), by activating mitochondrial SIRT3, normalizes reactive oxygen species level and mitochondrial integrity in hippocampus of the moderate grade hepatic encephalopathy (MoHE) rat model of ammonia neurotoxicity. To delineate the mechanism by which HKL does so, the present study describes activity versus level of the deacetylated mitochondrial Mn-superoxide dismutase (MnSOD) and expression of MnSOD versus levels of its main transcription regulators, FoxO3a and PGC1α, in the hippocampus of the MoHE rats. MoHE in rat was developed by administration of 100 mg/kg bw thioacetamide i.p. for 10 days. The study parameters were compared between the control, the MoHE rats and the MoHE rats treated with HKL (10 mg/Kg b.w.) for 7 days. As compared to control, the hippocampus mitochondria from MoHE rats showed a significantly declined activity of MnSOD vs enhanced lipid peroxidation coinciding with the increased level of its acetylated form. The HKL treatment could, however, normalize all these parameters in those MoHE rats. Also, a significantly reduced expression of MnSOD in the hippocampus of the MoHE rats coincided with a similar decline in transcript level of Foxo3a and Pgc1α. This was consistent with the reduced level of immuno-stained Foxo3a and Pgc1α proteins in hippocampus DG, CA1 and CA3 regions of those MoHE rats. However, all these factors were observed to be restored back to their normal levels due to the treatment with HKL. As HKL is a specific activator of mitochondrial SIRT3, these findings suggest involvement of Sirt3 activation led deacetylation of MnSOD and upregulation of its transcription activators, FoxO3a and PGC1α, in restoring mitochondrial MnSOD level in the hippocampus of the MoHE rat model of ammonia neurotoxicity.
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Affiliation(s)
- Anamika
- Biochemistry Section, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi, India
| | - Anima Roy
- Biochemistry Section, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi, India
| | - Surendra K Trigun
- Biochemistry Section, Department of Zoology, Institute of Science, Banaras Hindu University, Varanasi, India
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10
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Cellular Pathogenesis of Hepatic Encephalopathy: An Update. Biomolecules 2023; 13:biom13020396. [PMID: 36830765 PMCID: PMC9953810 DOI: 10.3390/biom13020396] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 01/01/2023] [Accepted: 02/17/2023] [Indexed: 02/22/2023] Open
Abstract
Hepatic encephalopathy (HE) is a neuropsychiatric syndrome derived from metabolic disorders due to various liver failures. Clinically, HE is characterized by hyperammonemia, EEG abnormalities, and different degrees of disturbance in sensory, motor, and cognitive functions. The molecular mechanism of HE has not been fully elucidated, although it is generally accepted that HE occurs under the influence of miscellaneous factors, especially the synergistic effect of toxin accumulation and severe metabolism disturbance. This review summarizes the recently discovered cellular mechanisms involved in the pathogenesis of HE. Among the existing hypotheses, ammonia poisoning and the subsequent oxidative/nitrosative stress remain the mainstream theories, and reducing blood ammonia is thus the main strategy for the treatment of HE. Other pathological mechanisms mainly include manganese toxicity, autophagy inhibition, mitochondrial damage, inflammation, and senescence, proposing new avenues for future therapeutic interventions.
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11
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Sepehrinezhad A, Shahbazi A, Sahab Negah S, Stolze Larsen F. New Insight Into Mechanisms of Hepatic Encephalopathy: An Integrative Analysis Approach to Identify Molecular Markers and Therapeutic Targets. Bioinform Biol Insights 2023; 17:11779322231155068. [PMID: 36814683 PMCID: PMC9940182 DOI: 10.1177/11779322231155068] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 01/17/2023] [Indexed: 02/19/2023] Open
Abstract
Hepatic encephalopathy (HE) is a set of complex neurological complications that arise from advanced liver disease. The precise molecular and cellular mechanism of HE is not fully understood. Differentially expressed genes (DEGs) from microarray technologies are powerful approaches to obtain new insight into the pathophysiology of HE. We analyzed microarray data sets of cirrhotic patients with HE from Gene Expression Omnibus to identify DEGs in postmortem cerebral tissues. Consequently, we uploaded significant DEGs into the STRING to specify protein-protein interactions. Cytoscape was used to reconstruct the genetic network and identify hub genes. Target genes were uploaded to different databases to perform comprehensive enrichment analysis and repurpose new therapeutic options for HE. A total of 457 DEGs were identified in 2 data sets totally from 12 cirrhotic patients with HE compared with 12 healthy subjects. We found that 274 genes were upregulated and 183 genes were downregulated. Network analyses on significant DEGs indicated 12 hub genes associated with HE. Enrichment analysis identified fatty acid beta-oxidation, cerebral organic acidurias, and regulation of actin cytoskeleton as main involved pathways associated with upregulated genes; serotonin receptor 2 and ELK-SRF/GATA4 signaling, GPCRs, class A rhodopsin-like, and p38 MAPK signaling pathway were related to downregulated genes. Finally, we predicted 39 probable effective drugs/agents for HE. This study not only confirms main important involved mechanisms of HE but also reveals some yet unknown activated molecular and cellular pathways in human HE. In addition, new targets were identified that could be of value in the future study of HE.
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Affiliation(s)
- Ali Sepehrinezhad
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran
- Neuroscience Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Ali Shahbazi
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran, Iran
- Cellular and Molecular Research Center, Iran University of Medical Sciences, Tehran, Iran
| | - Sajad Sahab Negah
- Neuroscience Research Center, Mashhad University of Medical Sciences, Mashhad, Iran
- Department of Neuroscience, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Fin Stolze Larsen
- Department of Hepatology CA-3163, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark
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Tsai CY, Wu JCC, Wu CJ, Chan SHH. Protective role of VEGF/VEGFR2 signaling against high fatality associated with hepatic encephalopathy via sustaining mitochondrial bioenergetics functions. J Biomed Sci 2022; 29:47. [PMID: 35786324 PMCID: PMC9251935 DOI: 10.1186/s12929-022-00831-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 06/27/2022] [Indexed: 11/30/2022] Open
Abstract
Background The lack of better understanding of the pathophysiology and cellular mechanisms associated with high mortality seen in hepatic encephalopathy (HE), a neurological complication arising from acute hepatic failure, remains a challenging medical issue. Clinical reports showed that the degree of baroreflex dysregulation is related to the severity of HE. Furthermore, mitochondrial dysfunction in the rostral ventrolateral medulla (RVLM), a key component of the baroreflex loop that maintains blood pressure and sympathetic vasomotor tone, is known to underpin impairment of baroreflex. Realizing that in addition to angiogenic and vasculogenic effects, by acting on its key receptor (VEGFR2), vascular endothelial growth factor (VEGF) elicits neuroprotection via maintenance of mitochondrial function, the guiding hypothesis of the present study is that the VEGF/VEGFR2 signaling plays a protective role against mitochondrial dysfunction in the RVLM to ameliorate baroreflex dysregulation that underpins the high fatality associated with HE. Methods Physiological, pharmacological and biochemical investigations were carried out in proof-of-concept experiments using an in vitro model of HE that involved incubation of cultured mouse hippocampal neurons with ammonium chloride. This was followed by corroboratory experiments employing a mouse model of HE, in which adult male C57BL/6 mice and VEGFR2 wild-type and heterozygous mice received an intraperitoneal injection of azoxymethane, a toxin used to induce acute hepatic failure. Results We demonstrated that VEGFR2 is present in cultured neurons, and observed that whereas recombinant VEGF protein maintained cell viability, gene-knockdown of vegfr2 enhanced the reduction of cell viability in our in vitro model of HE. In our in vivo model of HE, we found that VEGFR2 heterozygous mice exhibited shorter survival rate and time when compared to wild-type mice. In C57BL/6 mice, there was a progressive reduction in VEGFR2 mRNA and protein expression, mitochondrial membrane potential and ATP levels, alongside augmentation of apoptotic cell death in the RVLM, accompanied by a decrease in baroreflex-mediated sympathetic vasomotor tone and hypotension. Immunoneutralization of VEGF exacerbated all those biochemical and physiological events. Conclusions Our results suggest that, acting via VEGFR2, the endogenous VEGF plays a protective role against high fatality associated with HE by amelioration of the dysregulated baroreflex-mediated sympathetic vasomotor tone through sustaining mitochondrial bioenergetics functions and eliciting antiapoptotic action in the RVLM. Supplementary Information The online version contains supplementary material available at 10.1186/s12929-022-00831-0.
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Affiliation(s)
- Ching-Yi Tsai
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan.
| | - Jacqueline C C Wu
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan
| | - Chiung-Ju Wu
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan
| | - Samuel H H Chan
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, Taiwan
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13
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Busche M, Rabl D, Fischer J, Schmees C, Mayr T, Gebhardt R, Stelzle M. Continous, non-invasive monitoring of oxygen consumption in a parallelized microfluidic in vitro system provides novel insight into the response to nutrients and drugs of primary human hepatocytes. EXCLI JOURNAL 2022; 21:144-161. [PMID: 35145369 PMCID: PMC8822303 DOI: 10.17179/excli2021-4351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 11/29/2021] [Indexed: 11/18/2022]
Abstract
Oxygen plays a fundamental role in cellular energy metabolism, differentiation and cell biology in general. Consequently, in vitro oxygen sensing can be used to assess cell vitality and detect specific mechanisms of toxicity. In 2D in vitro models currently used, the oxygen supply provided by diffusion is generally too low, especially for cells having a high oxygen demand. In organ-on-chip systems, a more physiologic oxygen supply can be generated by establishing unidirectional perfusion. We established oxygen sensors in an easy-to-use and parallelized organ-on-chip system. We demonstrated the applicability of this system by analyzing the influence of fructose (40 mM, 80 mM), ammonium chloride (100 mM) and Na-diclofenac (50 µM, 150 µM, 450 µM, 1500 µM) on primary human hepatocytes (PHH). Fructose treatment for two hours showed an immediate drop of oxygen consumption (OC) with subsequent increase to nearly initial levels. Treatment with 80 mM glucose, 20 mM lactate or 20 mM glycerol did not result in any changes in OC which demonstrates a specific effect of fructose. Application of ammonium chloride for two hours did not show any immediate effects on OC, but qualitatively changed the cellular response to FCCP treatment. Na-diclofenac treatment for 24 hours led to a decrease of the maximal respiration and reserve capacity. We also demonstrated the stability of our system by repeatedly treating cells with 40 mM fructose, which led to similar cell responses on the same day as well as on subsequent days. In conclusion, our system enables in depth analysis of cellular respiration after substrate treatment in an unidirectional perfused organ-on-chip system.
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Affiliation(s)
- Marius Busche
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany,*To whom correspondence should be addressed: Marius Busche, NMI Natural and Medical Sciences Institute at the University of Tübingen, Markwiesenstraße 55, 72770 Reutlingen, Germany; Tel.: +49 7121 51530-0, E-mail:
| | - Dominik Rabl
- Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Graz, Austria
| | | | - Christian Schmees
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
| | - Torsten Mayr
- Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology, Graz, Austria,PyroScience AT GmbH, Aachen, Germany
| | - Rolf Gebhardt
- Rudolf-Schönheimer-Institute of Biochemistry, Leipzig University, Leipzig, Germany,InViSys-Tübingen GbR, Leipzig, Germany
| | - Martin Stelzle
- NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany
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14
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Kumar A, Welch N, Mishra S, Bellar A, Silva RN, Li L, Singh SS, Sharkoff M, Kerr A, Chelluboyina AK, Sekar J, Attaway AH, Hoppel C, Willard B, Davuluri G, Dasarathy S. Metabolic reprogramming during hyperammonemia targets mitochondrial function and postmitotic senescence. JCI Insight 2021; 6:154089. [PMID: 34935641 PMCID: PMC8783680 DOI: 10.1172/jci.insight.154089] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Accepted: 11/03/2021] [Indexed: 12/27/2022] Open
Abstract
Ammonia is a cytotoxic metabolite with pleiotropic molecular and metabolic effects, including senescence induction. During dysregulated ammonia metabolism, which occurs in chronic diseases, skeletal muscle becomes a major organ for nonhepatocyte ammonia uptake. Muscle ammonia disposal occurs in mitochondria via cataplerosis of critical intermediary metabolite α-ketoglutarate, a senescence-ameliorating molecule. Untargeted and mitochondrially targeted data were analyzed by multiomics approaches. These analyses were validated experimentally to dissect the specific mitochondrial oxidative defects and functional consequences, including senescence. Responses to ammonia lowering in myotubes and in hyperammonemic portacaval anastomosis rat muscle were studied. Whole-cell transcriptomics integrated with whole-cell, mitochondrial, and tissue proteomics showed distinct temporal clusters of responses with enrichment of oxidative dysfunction and senescence-related pathways/proteins during hyperammonemia and after ammonia withdrawal. Functional and metabolic studies showed defects in electron transport chain complexes I, III, and IV; loss of supercomplex assembly; decreased ATP synthesis; increased free radical generation with oxidative modification of proteins/lipids; and senescence-associated molecular phenotype–increased β-galactosidase activity and expression of p16INK, p21, and p53. These perturbations were partially reversed by ammonia lowering. Dysregulated ammonia metabolism caused reversible mitochondrial dysfunction by transcriptional and translational perturbations in multiple pathways with a distinct skeletal muscle senescence-associated molecular phenotype.
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Affiliation(s)
| | | | | | | | | | - Ling Li
- Proteomics & Metabolomics Core, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | | | | | | | | | | | | | - Charles Hoppel
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Belinda Willard
- Proteomics & Metabolomics Core, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, USA
| | - Gangarao Davuluri
- Department of Integrated Physiology and Molecular Metabolism, Pennington Biomedical Research Center, Baton Rouge, Louisiana, USA
| | - Srinivasan Dasarathy
- Department of Inflammation & Immunity and.,Department of Gastroenterology, Hepatology & Nutrition, Cleveland Clinic, Cleveland, Ohio, USA
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15
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Zhang IW, López-Vicario C, Duran-Güell M, Clària J. Mitochondrial Dysfunction in Advanced Liver Disease: Emerging Concepts. Front Mol Biosci 2021; 8:772174. [PMID: 34888354 PMCID: PMC8650317 DOI: 10.3389/fmolb.2021.772174] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 11/04/2021] [Indexed: 12/12/2022] Open
Abstract
Mitochondria are entrusted with the challenging task of providing energy through the generation of ATP, the universal cellular currency, thereby being highly flexible to different acute and chronic nutrient demands of the cell. The fact that mitochondrial diseases (genetic disorders caused by mutations in the nuclear or mitochondrial genome) manifest through a remarkable clinical variation of symptoms in affected individuals underlines the far-reaching implications of mitochondrial dysfunction. The study of mitochondrial function in genetic or non-genetic diseases therefore requires a multi-angled approach. Taking into account that the liver is among the organs richest in mitochondria, it stands to reason that in the process of unravelling the pathogenesis of liver-related diseases, researchers give special focus to characterizing mitochondrial function. However, mitochondrial dysfunction is not a uniformly defined term. It can refer to a decline in energy production, increase in reactive oxygen species and so forth. Therefore, any study on mitochondrial dysfunction first needs to define the dysfunction to be investigated. Here, we review the alterations of mitochondrial function in liver cirrhosis with emphasis on acutely decompensated liver cirrhosis and acute-on-chronic liver failure (ACLF), the latter being a form of acute decompensation characterized by a generalized state of systemic hyperinflammation/immunosuppression and high mortality rate. The studies that we discuss were either carried out in liver tissue itself of these patients, or in circulating leukocytes, whose mitochondrial alterations might reflect tissue and organ mitochondrial dysfunction. In addition, we present different methodological approaches that can be of utility to address the diverse aspects of hepatocyte and leukocyte mitochondrial function in liver disease. They include assays to measure metabolic fluxes using the comparatively novel Biolog’s MitoPlates in a 96-well format as well as assessment of mitochondrial respiration by high-resolution respirometry using Oroboros’ O2k-technology and Agilent Seahorse XF technology.
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Affiliation(s)
- Ingrid W Zhang
- Biochemistry and Molecular Genetics Service, Hospital Clínic-IDIBAPS, Barcelona, Spain.,European Foundation for the Study of Chronic Liver Failure (EF Clif) and Grifols Chair, Barcelona, Spain
| | - Cristina López-Vicario
- Biochemistry and Molecular Genetics Service, Hospital Clínic-IDIBAPS, Barcelona, Spain.,European Foundation for the Study of Chronic Liver Failure (EF Clif) and Grifols Chair, Barcelona, Spain.,CIBERehd, Barcelona, Spain
| | - Marta Duran-Güell
- Biochemistry and Molecular Genetics Service, Hospital Clínic-IDIBAPS, Barcelona, Spain.,European Foundation for the Study of Chronic Liver Failure (EF Clif) and Grifols Chair, Barcelona, Spain
| | - Joan Clària
- Biochemistry and Molecular Genetics Service, Hospital Clínic-IDIBAPS, Barcelona, Spain.,European Foundation for the Study of Chronic Liver Failure (EF Clif) and Grifols Chair, Barcelona, Spain.,CIBERehd, Barcelona, Spain.,Department of Biomedical Sciences, University of Barcelona, Barcelona, Spain
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16
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Zimmermann M, Reichert AS. Rapid metabolic and bioenergetic adaptations of astrocytes under hyperammonemia - a novel perspective on hepatic encephalopathy. Biol Chem 2021; 402:1103-1113. [PMID: 34331848 DOI: 10.1515/hsz-2021-0172] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 07/18/2021] [Indexed: 12/17/2022]
Abstract
Hepatic encephalopathy (HE) is a well-studied, neurological syndrome caused by liver dysfunctions. Ammonia, the major toxin during HE pathogenesis, impairs many cellular processes within astrocytes. Yet, the molecular mechanisms causing HE are not fully understood. Here we will recapitulate possible underlying mechanisms with a clear focus on studies revealing a link between altered energy metabolism and HE in cellular models and in vivo. The role of the mitochondrial glutamate dehydrogenase and its role in metabolic rewiring of the TCA cycle will be discussed. We propose an updated model of ammonia-induced toxicity that may also be exploited for therapeutic strategies in the future.
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Affiliation(s)
- Marcel Zimmermann
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
| | - Andreas S Reichert
- Institute of Biochemistry and Molecular Biology I, Medical Faculty, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Universitätsstraße 1, D-40225 Düsseldorf, Germany
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17
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Kim YK, Song J. Therapeutic Applications of Resveratrol in Hepatic Encephalopathy through Its Regulation of the Microbiota, Brain Edema, and Inflammation. J Clin Med 2021; 10:jcm10173819. [PMID: 34501267 PMCID: PMC8432232 DOI: 10.3390/jcm10173819] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/22/2021] [Accepted: 08/24/2021] [Indexed: 02/07/2023] Open
Abstract
Hepatic encephalopathy is a common complication in patients with liver cirrhosis and portosystemic shunting. Patients with hepatic encephalopathy present a variety of clinical features, including neuropsychiatric manifestations, cognitive dysfunction, impaired gut barrier function, hyperammonemia, and chronic neuroinflammation. These pathogeneses have been linked to various factors, including ammonia-induced oxidative stress, neuronal cell death, alterations in the gut microbiome, astrocyte swelling, and blood-brain barrier disruptions. Many researchers have focused on identifying novel therapeutics and prebiotics in the hope of improving the treatment of these conditions. Resveratrol is a natural polyphenic compound and is known to exert several pharmacological effects, including antioxidant, anti-inflammatory, and neuroprotective activities. Recent studies suggest that resveratrol contributes to improving the neuropathogenic effects of liver failure. Here, we review the current evidence describing resveratrol's effects in neuropathogenesis and its impact on the gut-liver axis relating to hepatic encephalopathy. We highlight the hypothesis that resveratrol exerts diverse effects in hepatic encephalopathy and suggest that these effects are likely mediated by changes to the gut microbiota, brain edema, and neuroinflammation.
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Affiliation(s)
- Young-Kook Kim
- Department of Biochemistry, Chonnam National University Medical School, Hwasun 58128, Jeollanam-do, Korea;
| | - Juhyun Song
- Department of Anatomy, Chonnam National University Medical School, Hwasun 58128, Jeollanam-do, Korea
- Correspondence: ; Tel.: +82-61-379-2706; Fax: +82-61-375-5834
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18
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Hashiesh HM, Sharma C, Goyal SN, Sadek B, Jha NK, Kaabi JA, Ojha S. A focused review on CB2 receptor-selective pharmacological properties and therapeutic potential of β-caryophyllene, a dietary cannabinoid. Biomed Pharmacother 2021; 140:111639. [PMID: 34091179 DOI: 10.1016/j.biopha.2021.111639] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Revised: 04/12/2021] [Accepted: 04/19/2021] [Indexed: 02/06/2023] Open
Abstract
The endocannabinoid system (ECS), a conserved physiological system emerged as a novel pharmacological target for its significant role and potential therapeutic benefits ranging from neurological diseases to cancer. Among both, CB1 and CB2R types, CB2R have received attention for its pharmacological effects as antioxidant, anti-inflammatory, immunomodulatory and antiapoptotic that can be achieved without causing psychotropic adverse effects through CB1R. The ligands activate CB2R are of endogenous, synthetic and plant origin. In recent years, β-caryophyllene (BCP), a natural bicyclic sesquiterpene in cannabis as well as non-cannabis plants, has received attention due to its selective agonist property on CB2R. BCP has been well studied in a variety of pathological conditions mediating CB2R selective agonist property. The focus of the present manuscript is to represent the CB2R selective agonist mediated pharmacological mechanisms and therapeutic potential of BCP. The present narrative review summarizes insights into the CB2R-selective pharmacological properties and therapeutic potential of BCP such as cardioprotective, hepatoprotective, neuroprotective, nephroprotective, gastroprotective, chemopreventive, antioxidant, anti-inflammatory, and immunomodulator. The available evidences suggest that BCP, can be an important candidate of plant origin endowed with CB2R selective properties that may provide a pharmacological rationale for its pharmacotherapeutic application and pharmaceutical development like a drug. Additionally, given the wide availability in edible plants and dietary use, with safety, and no toxicity, BCP can be promoted as a nutraceutical and functional food for general health and well-being. Further, studies are needed to explore pharmacological and pharmaceutical opportunities for therapeutic and preventive applications of use of BCP in human diseases.
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Affiliation(s)
- Hebaallah Mamdouh Hashiesh
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates
| | - Charu Sharma
- Department of Internal Medicine, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates
| | - Sameer N Goyal
- Shri Vile Parle Kelvani Mandal's Institute of Pharmacy, Dhule 424001, Maharashtra, India
| | - Bassem Sadek
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates
| | - Niraj Kumar Jha
- Department of Biotechnology, School of Engineering & Technology, Sharda University, Greater Noida, Uttar Pradesh 201310, India
| | - Juma Al Kaabi
- Department of Internal Medicine, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates
| | - Shreesh Ojha
- Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates; Zayed Bin Sultan Al Nahyan Center for Health Sciences, United Arab Emirates University, P.O. Box 17666, Al Ain, United Arab Emirates.
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19
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Limón ID, Angulo-Cruz I, Sánchez-Abdon L, Patricio-Martínez A. Disturbance of the Glutamate-Glutamine Cycle, Secondary to Hepatic Damage, Compromises Memory Function. Front Neurosci 2021; 15:578922. [PMID: 33584185 PMCID: PMC7873464 DOI: 10.3389/fnins.2021.578922] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Accepted: 01/06/2021] [Indexed: 12/13/2022] Open
Abstract
Glutamate fulfils many vital functions both at a peripheral level and in the central nervous system (CNS). However, hyperammonemia and hepatic failure induce alterations in glutamatergic neurotransmission, which may be the main cause of hepatic encephalopathy (HE), an imbalance which may explain damage to both learning and memory. Cognitive and motor alterations in hyperammonemia may be caused by a deregulation of the glutamate-glutamine cycle, particularly in astrocytes, due to the blocking of the glutamate excitatory amino-acid transporters 1 and 2 (EAAT1, EAAT2). Excess extracellular glutamate triggers mechanisms involving astrocyte-mediated inflammation, including the release of Ca2+-dependent glutamate from astrocytes, the appearance of excitotoxicity, the formation of reactive oxygen species (ROS), and cell damage. Glutamate re-uptake not only prevents excitotoxicity, but also acts as a vital component in synaptic plasticity and function. The present review outlines the evidence of the relationship between hepatic damage, such as that occurring in HE and hyperammonemia, and changes in glutamine synthetase function, which increase glutamate concentrations in the CNS. These conditions produce dysfunction in neuronal communication. The present review also includes data indicating that hyperammonemia is related to the release of a high level of pro-inflammatory factors, such as interleukin-6, by astrocytes. This neuroinflammatory condition alters the function of the membrane receptors, such as N-methyl-D-aspartate (NMDA), (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) AMPA, and γ-aminobutyric acid (GABA), thus affecting learning and spatial memory. Data indicates that learning and spatial memory, as well as discriminatory or other information acquisition processes in the CNS, are damaged by the appearance of hyperammonemia and, moreover, are associated with a reduction in the production of cyclic guanosine monophosphate (cGMP). Therefore, increased levels of pharmacologically controlled cGMP may be used as a therapeutic tool for improving learning and memory in patients with HE, hyperammonemia, cerebral oedema, or reduced intellectual capacity.
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Affiliation(s)
| | - Isael Angulo-Cruz
- Laboratorio de Neurofarmacología, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Lesli Sánchez-Abdon
- Laboratorio de Neurofarmacología, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
| | - Aleidy Patricio-Martínez
- Laboratorio de Neurofarmacología, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
- Facultad de Ciencias Biológicas, Benemérita Universidad Autónoma de Puebla, Puebla, Mexico
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20
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The nuclear factor kappa B (NF-κB) signaling pathway is involved in ammonia-induced mitochondrial dysfunction. Mitochondrion 2020; 57:63-75. [PMID: 33378713 DOI: 10.1016/j.mito.2020.12.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2020] [Revised: 12/17/2020] [Accepted: 12/21/2020] [Indexed: 12/12/2022]
Abstract
Hyperammonemia is very toxic to the brain, leading to inflammation, disruption of brain cellular energy metabolism and cognitive function. However, the underlying mechanism(s) for these impairments is still not fully understood. This study investigated the effects of ammonia in hippocampal astroglia derived from C57BL/6 mice. Parameters measured included oxygen consumption rates (OCR), ATP, cytochrome c oxidase (COX) activity, alterations in oxidative phosphorylation (OXPHOS), nuclear factor kappa B (NF-κB) subunits, key regulators of mitochondrial biogenesis (peroxisome proliferator-activated receptor gamma coactivator1-alpha (PGC-1α), calcium/calmodulin-dependent protein kinase II (CaMKII), cAMP-response element binding protein (CREB), nuclear factor (erythroid-derived 2)-like 2 (Nrf2), early growth response (Egr) factor family of proteins, and mitochondrial transcription factor A (TFAM). Ammonia was found to decrease mitochondrial numbers, potentially through a CaMKII-CREB-PGC1α-Nrf2 pathway in astroglia. Ammonia did not alter the levels of Egrs and TFAM in astroglia. Ammonia decreased OCR, ATP, COX, and OXPHOS levels in astroglia. To assess whether energy metabolism is reduced by ammonia through NF-κB associated pathways, astroglia were treated with ammonia alone or with NF-κB inhibitors such as Bay11-7082 or SN50. Mitochondrial OCR levels were reduced in the presence of NF-κB inhibitors; however co-treatment of NF-κB inhibitors and ammonia reversed mitochondrial deficits. Further, ammonia increased translocation of the NF-κB p65 into the nucleus of astroglia that correlates with an increased activity of NF-κB. These findings suggest that the NF-κB signaling pathway is putatively involved in ammonia-induced changes in bioenergetics in astroglia. Such research has critical implications for the treatment of disorders in which brain bioenergetics is compromised.
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21
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Dominguini D, Dall'igna DM, Nogueira L, Steckert AV, GonÇalves RC, Michels M, Quevedo J, Ritter C, Barichello T, Dal-Pizzol F. Ammonia exposition during gestation induces neonatal oxidative damage in the brain and long-term cognitive alteration in rats. AN ACAD BRAS CIENC 2020; 92:e20190925. [PMID: 33295575 DOI: 10.1590/0001-3765202020190925] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 10/07/2020] [Indexed: 11/22/2022] Open
Abstract
Ammonia is involved in the pathogenesis of neurological conditions associated with hyperammonemia, including hepatic encephalopathy. Few is known about the effects of gestational exposition to ammonia in the developing brain, and the possible long-term consequences of such exposure. We aimed to evaluate the effects of ammonia exposure during the gestation and the possible long-term cognitive alterations on pups. Eight female rats were divided into two groups: (1) control (saline solution); (2) ammonia (ammonium acetate, 2,5mmol/Kg). Each rat received a single subcutaneous injection during all gestational period. The brains from 1-day-old rats were obtained to the determination of thiobarbituric acid reactive species (TBARS), protein carbonyl and nitrite/nitrate levels. Some animals were followed 30 days after delivery and were subjected to the step-down inhibitory avoidance task. It was observed a significant increase in protein carbonyl, but not TBARS or nitrite/nitrate levels, in pups exposed to ammonia. Rats exposed to ammonia presented long-term cognitive impairment. Gestational exposition to ammonia induces protein oxidative damage in the neonatal rat brain, and long-term cognitive impairment.
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Affiliation(s)
- Diogo Dominguini
- Programa de Pós-Graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense/UNESC, Laboratório de Fisiopatologia Experimental, Av. Universitária, 1105, Universitário, 88806-000 Criciúma, SC, Brazil
| | - DhÉbora M Dall'igna
- Programa de Pós-Graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense/UNESC, Laboratório de Fisiopatologia Experimental, Av. Universitária, 1105, Universitário, 88806-000 Criciúma, SC, Brazil
| | - Lauro Nogueira
- Programa de Pós-Graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense/UNESC, Laboratório de Fisiopatologia Experimental, Av. Universitária, 1105, Universitário, 88806-000 Criciúma, SC, Brazil
| | - Amanda V Steckert
- Programa de Pós-Graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense/UNESC, Laboratório de Fisiopatologia Experimental, Av. Universitária, 1105, Universitário, 88806-000 Criciúma, SC, Brazil
| | - Renata C GonÇalves
- Programa de Pós-Graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense/UNESC, Laboratório de Fisiopatologia Experimental, Av. Universitária, 1105, Universitário, 88806-000 Criciúma, SC, Brazil
| | - Monique Michels
- Programa de Pós-Graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense/UNESC, Laboratório de Fisiopatologia Experimental, Av. Universitária, 1105, Universitário, 88806-000 Criciúma, SC, Brazil
| | - JoÃo Quevedo
- Translational Psychiatry Program, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth), Houston, TX, 77054, USA
- Center of Excellence on Mood Disorders, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth), Houston, TX, 77054, USA
- Neuroscience Graduate Program, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX, 77054, USA
| | - Cristiane Ritter
- Programa de Pós-Graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense/UNESC, Laboratório de Fisiopatologia Experimental, Av. Universitária, 1105, Universitário, 88806-000 Criciúma, SC, Brazil
| | - Tatiana Barichello
- Programa de Pós-Graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense/UNESC, Laboratório de Fisiopatologia Experimental, Av. Universitária, 1105, Universitário, 88806-000 Criciúma, SC, Brazil
- Translational Psychiatry Program, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth), Houston, TX, 77054, USA
- Center of Excellence on Mood Disorders, Department of Psychiatry and Behavioral Sciences, McGovern Medical School, The University of Texas Health Science Center at Houston (UTHealth), Houston, TX, 77054, USA
- Neuroscience Graduate Program, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX, 77054, USA
| | - Felipe Dal-Pizzol
- Programa de Pós-Graduação em Ciências da Saúde, Universidade do Extremo Sul Catarinense/UNESC, Laboratório de Fisiopatologia Experimental, Av. Universitária, 1105, Universitário, 88806-000 Criciúma, SC, Brazil
- Programa de Pós-Graduação em Ciências Médicas, Universidade Federal de Santa Catarina/UFSC, Centro de Excelência em Neurociências Aplicadas de Santa Catarina/ NENASC, Rua Eng. Agronômico Andrei Cristian Ferreira, s/n, Trindade, 88040-900 Florianópolis, SC, Brazil
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Drews L, Zimmermann M, Westhoff P, Brilhaus D, Poss RE, Bergmann L, Wiek C, Brenneisen P, Piekorz RP, Mettler-Altmann T, Weber APM, Reichert AS. Ammonia inhibits energy metabolism in astrocytes in a rapid and glutamate dehydrogenase 2-dependent manner. Dis Model Mech 2020; 13:dmm047134. [PMID: 32917661 PMCID: PMC7657470 DOI: 10.1242/dmm.047134] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Accepted: 09/02/2020] [Indexed: 01/02/2023] Open
Abstract
Astrocyte dysfunction is a primary factor in hepatic encephalopathy (HE) impairing neuronal activity under hyperammonemia. In particular, the early events causing ammonia-induced toxicity to astrocytes are not well understood. Using established cellular HE models, we show that mitochondria rapidly undergo fragmentation in a reversible manner upon hyperammonemia. Further, in our analyses, within a timescale of minutes, mitochondrial respiration and glycolysis were hampered, which occurred in a pH-independent manner. Using metabolomics, an accumulation of glucose and numerous amino acids, including branched chain amino acids, was observed. Metabolomic tracking of 15N-labeled ammonia showed rapid incorporation of 15N into glutamate and glutamate-derived amino acids. Downregulating human GLUD2 [encoding mitochondrial glutamate dehydrogenase 2 (GDH2)], inhibiting GDH2 activity by SIRT4 overexpression, and supplementing cells with glutamate or glutamine alleviated ammonia-induced inhibition of mitochondrial respiration. Metabolomic tracking of 13C-glutamine showed that hyperammonemia can inhibit anaplerosis of tricarboxylic acid (TCA) cycle intermediates. Contrary to its classical anaplerotic role, we show that, under hyperammonemia, GDH2 catalyzes the removal of ammonia by reductive amination of α-ketoglutarate, which efficiently and rapidly inhibits the TCA cycle. Overall, we propose a critical GDH2-dependent mechanism in HE models that helps to remove ammonia, but also impairs energy metabolism in mitochondria rapidly.
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Affiliation(s)
- Leonie Drews
- Institute for Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Marcel Zimmermann
- Institute for Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Philipp Westhoff
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
- Plant Metabolism and Metabolomics Laboratory, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Dominik Brilhaus
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
- Plant Metabolism and Metabolomics Laboratory, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Rebecca E Poss
- Institute for Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Laura Bergmann
- Institute for Biochemistry and Molecular Biology II, Medical Faculty, Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Constanze Wiek
- Department of Otorhinolaryngology and Head/Neck Surgery (ENT), Medical Faculty, Heinrich Heine University Düsseldorf, Moorenstr. 5, 40225 Düsseldorf, Germany
| | - Peter Brenneisen
- Institute for Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Roland P Piekorz
- Institute for Biochemistry and Molecular Biology II, Medical Faculty, Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Tabea Mettler-Altmann
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
- Plant Metabolism and Metabolomics Laboratory, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Andreas P M Weber
- Institute of Plant Biochemistry, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
- Plant Metabolism and Metabolomics Laboratory, Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
| | - Andreas S Reichert
- Institute for Biochemistry and Molecular Biology I, Medical Faculty, Heinrich Heine University Düsseldorf, Universitätsstr. 1, 40225 Düsseldorf, Germany
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23
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Jin X, Chen D, Wu F, Zhang L, Huang Y, Lin Z, Wang X, Wang R, Xu L, Chen Y. Hydrogen Sulfide Protects Against Ammonia-Induced Neurotoxicity Through Activation of Nrf2/ARE Signaling in Astrocytic Model of Hepatic Encephalopathy. Front Cell Neurosci 2020; 14:573422. [PMID: 33192318 PMCID: PMC7642620 DOI: 10.3389/fncel.2020.573422] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Accepted: 09/15/2020] [Indexed: 12/13/2022] Open
Abstract
Objective: Hepatic encephalopathy (HE) characterized by neuropsychiatric abnormalities is a major complication of cirrhosis with high mortality. However, the pathogenesis of HE has not been fully elucidated. This study aimed to determine endogenous hydrogen sulfide (H2S) in the blood of HE patients and investigate the role of H2S in an astrocytic model of HE. Methods: Patients with and without HE were recruited to determine plasma H2S levels and blood microbial 16S rRNA gene. Rat astrocytes were employed as a model of HE by treatment of NH4Cl. Exogenous H2S was preadded. Cell viability was measured by Cell Counting Kit-8 (CCK-8) assay, and cell death was evaluated by lactate dehydrogenase (LDH) release. Apoptosis was determined by Hoechst 33342/Propidium Iodide (PI) Double Staining and Western blot analysis of apoptosis-related protein expression. Intracellular reactive oxygen species (ROS) levels were assessed by flow cytometer. Expressions of Nrf2 and its downstream regulated genes were examined by immunofluorescence staining and Western blot, respectively. Nrf2 gene knockdown was performed by antisense shRNA of Nrf2 gene. Results: There was a significant decrease in H2S levels in cirrhotic patients with HE compared with without HE. Blood microbiota analyses revealed that certain strains associated with H2S production were negatively correlated with HE. In vitro, H2S markedly attenuated NH4Cl-induced cytotoxicity, oxidative stress, and apoptosis. This effect was mediated by Nrf2/ARE signaling, and knockdown of Nrf2 expression abolished the antagonistic effect of H2S on NH4Cl-induced neurotoxicity in astrocytes. Conclusion: Levels of H2S and bacteria associated with H2S production are decreased in HE, and H2S functions as the neuroprotector against NH4Cl-induced HE by activating Nrf2/ARE signaling of astrocytes.
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Affiliation(s)
- Xiaozhi Jin
- Department of Infectious Diseases, Wenzhou Key Laboratory of Hepatology, The First Affiliated Hospital of Wenzhou Medical University, Hepatology Institute of Wenzhou Medical University, Zhejiang Provincial Key Laboratory for Accurate Diagnosis and Treatment of Chronic Liver Diseases, Wenzhou, China
| | - Dazhi Chen
- Department of Gastroenterology, The First Hospital of Peking University, Beijing, China
| | - Faling Wu
- Department of Infectious Diseases, Wenzhou Key Laboratory of Hepatology, The First Affiliated Hospital of Wenzhou Medical University, Hepatology Institute of Wenzhou Medical University, Zhejiang Provincial Key Laboratory for Accurate Diagnosis and Treatment of Chronic Liver Diseases, Wenzhou, China
| | - Lei Zhang
- Department of Infectious Diseases, Wenzhou Key Laboratory of Hepatology, The First Affiliated Hospital of Wenzhou Medical University, Hepatology Institute of Wenzhou Medical University, Zhejiang Provincial Key Laboratory for Accurate Diagnosis and Treatment of Chronic Liver Diseases, Wenzhou, China
| | - Yu Huang
- Department of Infectious Diseases, Wenzhou Key Laboratory of Hepatology, The First Affiliated Hospital of Wenzhou Medical University, Hepatology Institute of Wenzhou Medical University, Zhejiang Provincial Key Laboratory for Accurate Diagnosis and Treatment of Chronic Liver Diseases, Wenzhou, China
| | - Zhuo Lin
- Department of Infectious Diseases, Wenzhou Key Laboratory of Hepatology, The First Affiliated Hospital of Wenzhou Medical University, Hepatology Institute of Wenzhou Medical University, Zhejiang Provincial Key Laboratory for Accurate Diagnosis and Treatment of Chronic Liver Diseases, Wenzhou, China
| | - Xiaodong Wang
- Department of Infectious Diseases, Wenzhou Key Laboratory of Hepatology, The First Affiliated Hospital of Wenzhou Medical University, Hepatology Institute of Wenzhou Medical University, Zhejiang Provincial Key Laboratory for Accurate Diagnosis and Treatment of Chronic Liver Diseases, Wenzhou, China
| | - Rui Wang
- Department of Infectious Diseases, Wenzhou Key Laboratory of Hepatology, The First Affiliated Hospital of Wenzhou Medical University, Hepatology Institute of Wenzhou Medical University, Zhejiang Provincial Key Laboratory for Accurate Diagnosis and Treatment of Chronic Liver Diseases, Wenzhou, China
| | - Lanman Xu
- Department of Infectious Diseases and Liver Diseases, Ningbo Medical Center Lihuili Hospital, Ningbo, China.,Department of Infectious Diseases and Liver Diseases, The Affiliated Lihuili Hospital of Ningbo University, Ningbo, China
| | - Yongping Chen
- Department of Infectious Diseases, Wenzhou Key Laboratory of Hepatology, The First Affiliated Hospital of Wenzhou Medical University, Hepatology Institute of Wenzhou Medical University, Zhejiang Provincial Key Laboratory for Accurate Diagnosis and Treatment of Chronic Liver Diseases, Wenzhou, China
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24
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Kerbert AJC, Jalan R. Recent advances in understanding and managing hepatic encephalopathy in chronic liver disease. F1000Res 2020; 9. [PMID: 32399191 PMCID: PMC7194462 DOI: 10.12688/f1000research.22183.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 04/21/2020] [Indexed: 12/12/2022] Open
Abstract
Hepatic encephalopathy (HE) is a common, severe complication of advanced chronic liver disease (CLD) and has a devastating impact on the patient’s quality of life and prognosis. The neurotoxin ammonia and the presence of systemic and neurological inflammation are considered the key drivers of this neuropsychiatric syndrome. Treatment options available in routine clinical practice are limited, and the development of novel therapies is hampered owing to the complexity and heterogeneity of HE. This review article aims to outline the current understanding of the pathomechanisms of HE and the recent advances in the identification and development of novel therapeutic targets.
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Affiliation(s)
- Annarein J C Kerbert
- Institute for Liver and Digestive Health, University College London, Royal Free Campus, Rowland Hill Street, London, NW3 2PF, UK
| | - Rajiv Jalan
- Institute for Liver and Digestive Health, University College London, Royal Free Campus, Rowland Hill Street, London, NW3 2PF, UK
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25
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Sepehrinezhad A, Zarifkar A, Namvar G, Shahbazi A, Williams R. Astrocyte swelling in hepatic encephalopathy: molecular perspective of cytotoxic edema. Metab Brain Dis 2020; 35:559-578. [PMID: 32146658 DOI: 10.1007/s11011-020-00549-8] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 02/12/2020] [Indexed: 02/06/2023]
Abstract
Hepatic encephalopathy (HE) may occur in patients with liver failure. The most critical pathophysiologic mechanism of HE is cerebral edema following systemic hyperammonemia. The dysfunctional liver cannot eliminate circulatory ammonia, so its plasma and brain levels rise sharply. Astrocytes, the only cells that are responsible for ammonia detoxification in the brain, are dynamic cells with unique phenotypic properties that enable them to respond to small changes in their environment. Any pathological changes in astrocytes may cause neurological disturbances such as HE. Astrocyte swelling is the leading cause of cerebral edema, which may cause brain herniation and death by increasing intracranial pressure. Various factors may have a role in astrocyte swelling. However, the exact molecular mechanism of astrocyte swelling is not fully understood. This article discusses the possible mechanisms of astrocyte swelling which related to hyperammonia, including the possible roles of molecules like glutamine, lactate, aquaporin-4 water channel, 18 KDa translocator protein, glial fibrillary acidic protein, alanine, glutathione, toll-like receptor 4, epidermal growth factor receptor, glutamate, and manganese, as well as inflammation, oxidative stress, mitochondrial permeability transition, ATP depletion, and astrocyte senescence. All these agents and factors may be targeted in therapeutic approaches to HE.
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Affiliation(s)
- Ali Sepehrinezhad
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences (IUMS), Tehran, Iran
| | - Asadollah Zarifkar
- Shiraz Neuroscience Research Center and Department of Physiology, Shiraz University of Medical Sciences (SUMS), Shiraz, Iran
| | - Gholamreza Namvar
- Department of Neuroscience and Cognition, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Ali Shahbazi
- Department of Neuroscience, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences (IUMS), Tehran, Iran.
- Cellular and Molecular Research Center, Iran University of Medical Sciences (IUMS), Tehran, Iran.
| | - Roger Williams
- The Institute of Hepatology London and Foundation for Liver Research, 111 Coldharbour Lane, London, SE5 9NT, UK.
- Faculty of Life Sciences & Medicine, King's College London, London, UK.
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26
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Liotta EM, Kimberly WT. Cerebral edema and liver disease: Classic perspectives and contemporary hypotheses on mechanism. Neurosci Lett 2020; 721:134818. [PMID: 32035166 DOI: 10.1016/j.neulet.2020.134818] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2019] [Revised: 02/01/2020] [Accepted: 02/03/2020] [Indexed: 02/07/2023]
Abstract
Liver disease is a growing public health concern. Hepatic encephalopathy, the syndrome of brain dysfunction secondary to liver disease, is a frequent complication of both acute and chronic liver disease and cerebral edema (CE) is a key feature. While altered ammonia metabolism is a key contributor to hepatic encephalopathy and CE in liver disease, there is a growing appreciation that additional mechanisms contribute to CE. In this review we will begin by presenting three classic perspectives that form a foundation for a discussion of CE in liver disease: 1) CE is unique to acute liver failure, 2) CE in liver disease is only cytotoxic, and 3) CE in liver disease is primarily an osmotically mediated consequence of ammonia and glutamine metabolism. We will present each classic perspective along with more recent observations that call in to question that classic perspective. After highlighting these areas of debate, we will explore the leading contemporary mechanisms hypothesized to contribute to CE during liver disease.
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Affiliation(s)
- Eric M Liotta
- Northwestern University-Feinberg School of Medicine, Department of Neurology, United States; Northwestern University-Feinberg School of Medicine, Department of Surgery, Division of Organ Transplantation, United States; Northwestern University Transplant Outcomes Research Collaboration, United States.
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27
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Lu K, Zimmermann M, Görg B, Bidmon HJ, Biermann B, Klöcker N, Häussinger D, Reichert AS. Hepatic encephalopathy is linked to alterations of autophagic flux in astrocytes. EBioMedicine 2019; 48:539-553. [PMID: 31648987 PMCID: PMC6838440 DOI: 10.1016/j.ebiom.2019.09.058] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Revised: 09/18/2019] [Accepted: 09/19/2019] [Indexed: 02/07/2023] Open
Abstract
Background Hepatic encephalopathy (HE) is a severe neuropsychiatric syndrome caused by various types of liver failure resulting in hyperammonemia-induced dysfunction of astrocytes. It is unclear whether autophagy, an important pro-survival pathway, is altered in the brains of ammonia-intoxicated animals as well as in HE patients. Methods Using primary rat astrocytes, a co-culture model of primary mouse astrocytes and neurons, an in vivo rat HE model, and post mortem brain samples of liver cirrhosis patients with HE we analyzed whether and how hyperammonemia modulates autophagy. Findings We show that autophagic flux is efficiently inhibited after administration of ammonia in astrocytes. This occurs in a fast, reversible, time-, dose-, and ROS-dependent manner and is mediated by ammonia-induced changes in intralysosomal pH. Autophagic flux is also strongly inhibited in the cerebral cortex of rats after acute ammonium intoxication corroborating our results using an in vivo rat HE model. Transglutaminase 2 (TGM2), a factor promoting autophagy, is upregulated in astrocytes of in vitro- and in vivo-HE models as well as in post mortem brain samples of liver cirrhosis patients with HE, but not in patients without HE. LC3, a commonly used autophagy marker, is significantly increased in the brain of HE patients. Ammonia also modulated autophagy moderately in neuronal cells. We show that taurine, known to ameliorate several parameters caused by hyperammonemia in patients suffering from liver failure, is highly potent in reducing ammonia-induced impairment of autophagic flux. This protective effect of taurine is apparently not linked to inhibition of mTOR signaling but rather to reducing ammonia-induced ROS formation. Interpretation Our data support a model in which autophagy aims to counteract ammonia-induced toxicity, yet, as acidification of lysosomes is impaired, possible protective effects thereof, are hampered. We propose that modulating autophagy in astrocytes and/or neurons, e.g. by taurine, represents a novel strategy to treat liver diseases associated with HE. Funding Supported by the DFG, CRC974 “Communication and Systems Relevance in Liver Injury and Regeneration“, Düsseldorf (Project number 190586431) Projects A05 (DH), B04 (BG), B05 (NK), and B09 (ASR).
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Affiliation(s)
- Kaihui Lu
- Institute of Biochemistry and Molecular Biology I, Heinrich Heine University Düsseldorf, Medical Faculty, Düsseldorf, Germany
| | - Marcel Zimmermann
- Institute of Biochemistry and Molecular Biology I, Heinrich Heine University Düsseldorf, Medical Faculty, Düsseldorf, Germany
| | - Boris Görg
- Department of Gastroenterology, Hepatology and Infectious Diseases, Heinrich Heine University Düsseldorf, Medical Faculty, Düsseldorf, Germany
| | - Hans-Jürgen Bidmon
- C. & O. Vogt Institute for Brain Research, Heinrich Heine University Düsseldorf, Medical Faculty, Düsseldorf, Germany
| | - Barbara Biermann
- Institute of Neural and Sensory Physiology, Heinrich Heine University Düsseldorf, Medical Faculty, Düsseldorf, Germany
| | - Nikolaj Klöcker
- Institute of Neural and Sensory Physiology, Heinrich Heine University Düsseldorf, Medical Faculty, Düsseldorf, Germany
| | - Dieter Häussinger
- Department of Gastroenterology, Hepatology and Infectious Diseases, Heinrich Heine University Düsseldorf, Medical Faculty, Düsseldorf, Germany
| | - Andreas S Reichert
- Institute of Biochemistry and Molecular Biology I, Heinrich Heine University Düsseldorf, Medical Faculty, Düsseldorf, Germany.
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28
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Ammonia-induced mitochondrial impairment is intensified by manganese co-exposure: relevance to the management of subclinical hepatic encephalopathy and cirrhosis-associated brain injury. Clin Exp Hepatol 2019; 5:109-117. [PMID: 31501786 PMCID: PMC6728860 DOI: 10.5114/ceh.2019.85071] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2018] [Accepted: 10/29/2018] [Indexed: 12/30/2022] Open
Abstract
Aim of the study Hepatic encephalopathy (HE) is a neuropsychiatric syndrome ensuing from liver failure. The liver is the major site of ammonia detoxification in the human body. Hence, acute and chronic liver dysfunction can lead to hyperammonemia. Manganese (Mn) is a trace element incorporated in several physiological processes in the human body. Mn is excreted through bile. It has been found that cirrhosis is associated with hyperammonemia as well as body Mn accumulation. The brain is the primary target organ for both ammonia and Mn toxicity. On the other hand, brain mitochondria impairment is involved in the mechanism of Mn and ammonia neurotoxicity. Material and methods The current study was designed to evaluate the effect of Mn and ammonia and their combination on mitochondrial indices of functionality in isolated brain mitochondria. Isolated brain mitochondria were exposed to increasing concentrations of ammonia and Mn alone and/or in combination and several mitochondrial indices were assessed. Results The collapse of mitochondrial membrane potential, increased mitochondrial permeabilization, reactive oxygen species formation, and a significant decrease in mitochondrial dehydrogenase activity and ATP content were evident in Mn-exposed (0.005-1 mM) brain mitochondria. On the other hand, ammonia (0.005-0.5 mM) caused no significant changes in brain mitochondrial function. It was found that co-exposure of the brain mitochondria to Mn and ammonia causes more evident mitochondrial impairment in comparison with Mn and/or ammonia alone. Conclusions These data indicate additive toxicity of ammonia and Mn in isolated brain mitochondria exposed to these neurotoxins.
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29
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Heidari R. Brain mitochondria as potential therapeutic targets for managing hepatic encephalopathy. Life Sci 2019; 218:65-80. [DOI: 10.1016/j.lfs.2018.12.030] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Revised: 12/08/2018] [Accepted: 12/16/2018] [Indexed: 02/07/2023]
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30
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Wang F, Chen S, Jiang Y, Zhao Y, Sun L, Zheng B, Chen L, Liu Z, Zheng X, Yi K, Li C, Zhou X. Effects of ammonia on apoptosis and oxidative stress in bovine mammary epithelial cells. Mutagenesis 2019; 33:291-299. [PMID: 30184101 DOI: 10.1093/mutage/gey023] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 08/09/2018] [Indexed: 12/21/2022] Open
Abstract
Ammonia, produced mainly from the deamination of amino acids and glutamine, is one of the major toxic components in blood and tissues that may affect bovine health. However, the physiological and pathological roles of ammonia in the mammary glands are not understood clearly. In the present study, the bovine mammary epithelial cell line (MAC-T) was utilised as an in vitro model to determine the effects of ammonia on bovine mammary gland. We demonstrated that ammonia stimulated the production of intracellular reactive oxygen species, decreased mitochondrial membrane potential, interrupted intracellular calcium ion (Ca2+) homeostasis and induced cell apoptosis. Ammonia also significantly reduced cell viability and increased the proportion of apoptotic cells through enhancing the level of p53 phosphorylation and increasing the expressions of BAX, caspase 8, caspase 9, caspase 3. Interestingly, bumetanide, a specific Na+ K+ 2Cl--cotransporter inhibitor, dramatically abolished the damaging effects of ammonia on the cells. These data suggest that ammonia exposure induces apoptosis in bovine mammary epithelial cells via activation of the p53 pathway and the mitochondrial apoptotic pathway, and that these effects involved the Na+ K+ 2Cl--cotransporter.
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Affiliation(s)
- Fengge Wang
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Shuxiong Chen
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Yanwen Jiang
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Yun Zhao
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Liting Sun
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Biaobiao Zheng
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Lu Chen
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Zhuo Liu
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Xue Zheng
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Kangle Yi
- Hunan Institute of Animal and Veterinary Science, Changsha, Hunan, P.R. China
| | - Chunjin Li
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
| | - Xu Zhou
- College of Animal Sciences, Jilin University, Changchun, Jilin, P.R. China
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31
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Zielonka M, Probst J, Carl M, Hoffmann GF, Kölker S, Okun JG. Bioenergetic dysfunction in a zebrafish model of acute hyperammonemic decompensation. Exp Neurol 2019; 314:91-99. [PMID: 30653968 DOI: 10.1016/j.expneurol.2019.01.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 12/18/2018] [Accepted: 01/12/2019] [Indexed: 12/30/2022]
Abstract
Acute hyperammonemic encephalopathy is a life-threatening manifestation of individuals with urea cycle disorders, which is associated with high mortality rates and severe neurological sequelae in survivors. Cerebral bioenergetic failure has been proposed as one of the key mechanisms underlying hyperammonemia-induced brain damage, but data supporting this hypothesis remain inconclusive and partially contradictory. Using a previously established zebrafish model of acute hyperammonemic decompensation, we unraveled that acute hyperammonemia leads to a transamination-dependent withdrawal of 2-oxoglutarate (alpha-ketoglutarate) from the tricarboxylic acid (TCA) cycle with consecutive TCA cycle dysfunction, ultimately causing impaired oxidative phosphorylation with ATP shortage, decreased ATP/ADP-ratio and elevated lactate concentrations. Thus, our study supports and extends the hypothesis that cerebral bioenergetic dysfunction is an important pathophysiological hallmark of hyperammonemia-induced neurotoxicity.
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Affiliation(s)
- Matthias Zielonka
- Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, University Hospital Heidelberg, Heidelberg, Germany; Heidelberg Research Center for Molecular Medicine (HRCMM), Heidelberg, Germany.
| | - Joris Probst
- Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Matthias Carl
- Center for Integrative Biology (CIBIO), Laboratory of Translational Neurogenetics, University of Trento, Trento, Italy
| | - Georg Friedrich Hoffmann
- Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Stefan Kölker
- Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, University Hospital Heidelberg, Heidelberg, Germany
| | - Jürgen Günther Okun
- Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, University Hospital Heidelberg, Heidelberg, Germany
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Silencing of Transcription Factor Sp1 Promotes SN1 Transporter Regulation by Ammonia in Mouse Cortical Astrocytes. Int J Mol Sci 2019; 20:ijms20020234. [PMID: 30634395 PMCID: PMC6359076 DOI: 10.3390/ijms20020234] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 12/27/2018] [Accepted: 12/27/2018] [Indexed: 12/15/2022] Open
Abstract
The involvement of the astrocytic SN1 (SNAT3) transporter in ammonia-induced l-glutamine retention was recently documented in mouse-cultured astrocytes. Here we investigated the involvement of specificity protein 1 (Sp1) transcription factor in SN1 regulation in ammonium chloride (“ammonia”)-treated astrocytes. Sp1 expression and its cellular localization were determined using real-time qPCR, Western blot, and confocal microscopy. Sp1 binding to Snat3 promoter was analyzed by chromatin immunoprecipitation. The role of Sp1 in SN1 expression and SN1-mediated [3H]glutamine uptake in ammonia-treated astrocytes was verified using siRNA and mithramycin A. The involvement of protein kinase C (PKC) isoforms in Sp1 level/phosphorylation status was verified using siRNA technology. Sp1 translocation to the nuclei and its enhanced binding to the Snat3 promoter, along with Sp1 dependence of system N-mediated [3H]glutamine uptake, were observed in astrocytes upon ammonia exposure. Ammonia decreased the level of phosphorylated Sp1, and the effect was reinforced by long-term incubation with PKC modulator, phorbol 12-myristate 13-acetate, which is a treatment likely to dephosphorylate Sp1. Furthermore, silencing of the PKCδ isoform appears to enhance the ammonia effect on the Sp1 level. Collectively, the results demonstrate the regulatory role of Sp1 in regulation of SN1 expression and activity in ammonia-treated astrocytes and implicate altered Sp1 phosphorylation status in this capacity.
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Cong M, Wu H, Cao T, Ji C, Lv J. Effects of ammonia nitrogen on gill mitochondria in clam Ruditapes philippinarum. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2019; 65:46-52. [PMID: 30529996 DOI: 10.1016/j.etap.2018.12.003] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 11/07/2018] [Accepted: 12/02/2018] [Indexed: 06/09/2023]
Abstract
Ammonia nitrogen exposure has been found to significantly increase the early apoptosis rates of gill cells, affect the contents of ATP and disturb expressions of calcium-related genes in clam Ruditapes philippinarum. Mitochondria are the centers for energy production, initiation of apoptosis and calcium signal regulation. It is hypothesized that gill mitochondrion is a target organelle for the ammonia nitrogen. Thus, ATP metabolism together with ATP-consuming functions would be interfered by ammonia exposure. In the present study, mitochondrial transmembrane potential (MTP), ATPase activities, gill functions in clearance and respiration, and histological changes were detected to characterize the effects of ammonia to the gill mitochondria in clam R. philippinarum. Results indicated that ammonia exposure led to significant decreases in MTP, Ca2+-ATPase activity and clearance rates. However, different concentrations of ammonia nitrogen induced different variations on H+, K+-ATPase activity and respiration rates. Histological observation revealed that subacute exposure of ammonia damaged the microstructure of gill tissues. Therefore, ammonia exposure dramatically damaged the normal structure and function of mitochondria, resulting in irreversible damage in energy formation and supply. In addition, it affected Ca2+ and K+ metabolism and inhibited food intake and respiration in clam R. philippinarum.
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Affiliation(s)
- Ming Cong
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Provincial Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai 264003, PR China
| | - Huifeng Wu
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Provincial Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai 264003, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, PR China.
| | - Tengfei Cao
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Provincial Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai 264003, PR China; Biology School of Yantai University, Yantai 264005, PR China
| | - Chenglong Ji
- Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research (YIC), Chinese Academy of Sciences (CAS), Shandong Provincial Key Laboratory of Coastal Environmental Processes, YICCAS, Yantai 264003, PR China; Laboratory for Marine Fisheries Science and Food Production Processes, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266237, PR China
| | - Jiasen Lv
- Biology School of Yantai University, Yantai 264005, PR China
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Acar A, Yalçin E, Çavuşoğlu K. Protective Effects of β-Carotene Against Ammonium Sulfate Toxicity: Biochemical and Histopathological Approach in Mice Model. J Med Food 2018; 21:1145-1149. [DOI: 10.1089/jmf.2017.4164] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Ali Acar
- Vocational School of Health Services, Department of Medical Services and Techniques; Faculty of Science and Art; Giresun University, Giresun, Turkey
| | - Emine Yalçin
- Department of Biology, Faculty of Science and Art; Giresun University, Giresun, Turkey
| | - Kültiğin Çavuşoğlu
- Department of Biology, Faculty of Science and Art; Giresun University, Giresun, Turkey
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Zielonka M, Breuer M, Okun JG, Carl M, Hoffmann GF, Kölker S. Pharmacologic rescue of hyperammonemia-induced toxicity in zebrafish by inhibition of ornithine aminotransferase. PLoS One 2018; 13:e0203707. [PMID: 30199544 PMCID: PMC6130883 DOI: 10.1371/journal.pone.0203707] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 08/24/2018] [Indexed: 12/30/2022] Open
Abstract
Hyperammonemia is the common biochemical hallmark of urea cycle disorders, activating neurotoxic pathways. If untreated, affected individuals have a high risk of irreversible brain damage and mortality. Here we show that acute hyperammonemia strongly enhances transamination-dependent formation of osmolytic glutamine and excitatory glutamate, thereby inducing neurotoxicity and death in ammoniotelic zebrafish larvae via synergistically acting overactivation of NMDA receptors and bioenergetic impairment induced by depletion of 2-oxoglutarate. Intriguingly, specific and irreversible inhibition of ornithine aminotransferase (OAT) by 5-fluoromethylornithine rescues zebrafish from lethal concentrations of ammonium acetate and corrects hyperammonemia-induced biochemical alterations. Thus, OAT inhibition is a promising and effective therapeutic approach for preventing neurotoxicity and mortality in acute hyperammonemia.
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Affiliation(s)
- Matthias Zielonka
- University Hospital Heidelberg, Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, Heidelberg, Germany
- Heidelberg Research Center for Molecular Medicine (HRCMM), Heidelberg, Germany
- * E-mail:
| | - Maximilian Breuer
- University Hospital Heidelberg, Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, Heidelberg, Germany
| | - Jürgen Günther Okun
- University Hospital Heidelberg, Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, Heidelberg, Germany
| | - Matthias Carl
- Heidelberg University, Medical Faculty Mannheim, Department of Cell and Molecular Biology, Mannheim, Germany
- University of Trento, Center for Integrative Biology (CIBIO), Laboratory of Translational Neurogenetics, Trento, Italy
| | - Georg Friedrich Hoffmann
- University Hospital Heidelberg, Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, Heidelberg, Germany
| | - Stefan Kölker
- University Hospital Heidelberg, Center for Child and Adolescent Medicine, Division for Pediatric Neurology and Metabolic Medicine, Heidelberg, Germany
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Wilson CS, Mongin AA. Cell Volume Control in Healthy Brain and Neuropathologies. CURRENT TOPICS IN MEMBRANES 2018; 81:385-455. [PMID: 30243438 DOI: 10.1016/bs.ctm.2018.07.006] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Regulation of cellular volume is a critical homeostatic process that is intimately linked to ionic and osmotic balance in the brain tissue. Because the brain is encased in the rigid skull and has a very complex cellular architecture, even minute changes in the volume of extracellular and intracellular compartments have a very strong impact on tissue excitability and function. The failure of cell volume control is a major feature of several neuropathologies, such as hyponatremia, stroke, epilepsy, hyperammonemia, and others. There is strong evidence that such dysregulation, especially uncontrolled cell swelling, plays a major role in adverse pathological outcomes. To protect themselves, brain cells utilize a variety of mechanisms to maintain their optimal volume, primarily by releasing or taking in ions and small organic molecules through diverse volume-sensitive ion channels and transporters. In principle, the mechanisms of cell volume regulation are not unique to the brain and share many commonalities with other tissues. However, because ions and some organic osmolytes (e.g., major amino acid neurotransmitters) have a strong impact on neuronal excitability, cell volume regulation in the brain is a surprisingly treacherous process, which may cause more harm than good. This topical review covers the established and emerging information in this rapidly developing area of physiology.
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Affiliation(s)
- Corinne S Wilson
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States
| | - Alexander A Mongin
- Department of Neuroscience and Experimental Therapeutics, Albany Medical College, Albany, NY, United States; Department of Biophysics and Functional Diagnostics, Siberian State Medical University, Tomsk, Russian Federation
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Cai X, Hu F, Feng G, Kwok RTK, Liu B, Tang BZ. Organic Mitoprobes based on Fluorogens with Aggregation-Induced Emission. Isr J Chem 2018. [DOI: 10.1002/ijch.201800031] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Xiaolei Cai
- Department of Chemical and Biomolecular Engineering; National University of Singapore; 4 Engineering Drive 4 Singapore 117585
| | - Fang Hu
- Department of Chemical and Biomolecular Engineering; National University of Singapore; 4 Engineering Drive 4 Singapore 117585
| | - Guangxue Feng
- Department of Chemical and Biomolecular Engineering; National University of Singapore; 4 Engineering Drive 4 Singapore 117585
| | - Ryan Tsz Kin Kwok
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Institute of Molecular Functional Materials, Institute for Advanced Study and Division of Life Science; The Hong Kong University of Science and Technology; Clear Water Bay, Kowloon, Hong Kong China
| | - Bin Liu
- Department of Chemical and Biomolecular Engineering; National University of Singapore; 4 Engineering Drive 4 Singapore 117585
| | - Ben Zhong Tang
- Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Institute of Molecular Functional Materials, Institute for Advanced Study and Division of Life Science; The Hong Kong University of Science and Technology; Clear Water Bay, Kowloon, Hong Kong China
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Abstract
Hepatic encephalopathy (HE) is a common complication of liver dysfunction, including acute liver failure and liver cirrhosis. HE presents as a spectrum of neuropsychiatric symptoms ranging from subtle fluctuating cognitive impairment to coma. It is a significant contributor of morbidity in patients with liver disease. HE is observed in acute liver failure, liver bypass procedures, for example, shunt surgry and transjugular intrahepatic portosystemic shunt, and cirrhosis. These are classified as Type A, B and C HE, respectively. HE can also be classified according to whether its presence is overt or covert. The pathogenesis is linked with ammonia and glutamine production, and treatment is based on mechanisms to reduce the formation and/or removal of these compounds. There is no specific diagnostic test for HE, and diagnosis is based on clinical suspicion, excluding other causes and use of clinical tests that may support its diagnosis. Many tests are used in trials and experimentally, but have not yet gained universal acceptance. This review focuses on the definitions, pathogenesis and treatment of HE. Consideration will be given to existing treatment, including avoidance of precipitating factors and novel therapies such as prebiotics, probiotics, antibiotics, laxatives, branched-chain amino acids, shunt embolization and the importance of considering liver transplant in appropriate cases.
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Affiliation(s)
| | - Mark Alexander Ellul
- Faculty of Health and Life Sciences, Institute of Infection and Global Health, University of Liverpool, Liverpool, UK
| | - Timothy JS Cross
- Department of Gastroenterology, Royal Liverpool University Hospital
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Woodhouse CA, Patel VC, Singanayagam A, Shawcross DL. Review article: the gut microbiome as a therapeutic target in the pathogenesis and treatment of chronic liver disease. Aliment Pharmacol Ther 2018; 47:192-202. [PMID: 29083037 DOI: 10.1111/apt.14397] [Citation(s) in RCA: 128] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 06/06/2017] [Accepted: 10/03/2017] [Indexed: 12/13/2022]
Abstract
BACKGROUND Mortality from chronic liver disease is rising exponentially. The liver is intimately linked to the gut via the portal vein, and exposure to gut microbiota and their metabolites translocating across the gut lumen may impact upon both the healthy and diseased liver. Modulation of gut microbiota could prove to be a potential therapeutic target. AIM To characterise the changes in the gut microbiome that occur in chronic liver disease and to assess the impact of manipulation of the microbiome on the liver. METHODS We conducted a PubMed search using search terms including 'microbiome', 'liver' and 'cirrhosis' as well as 'non-alcoholic fatty liver disease', 'steatohepatitis', 'alcohol' and 'primary sclerosing cholangitis'. Relevant articles were also selected from references of articles and review of the ClinicalTrials.gov website. RESULTS Reduced bacterial diversity, alcohol sensitivity and the development of gut dysbiosis are seen in several chronic liver diseases, including non-alcoholic fatty liver disease, alcohol-related liver disease and primary sclerosing cholangitis. Perturbations in gut commensals could lead to deficient priming of the immune system predisposing the development of immune-mediated diseases. Furthermore, transfer of stool from an animal with the metabolic syndrome may induce steatosis in a healthy counterpart. Patients with cirrhosis develop dysbiosis, small bowel bacterial overgrowth and increased gut wall permeability, allowing bacterial translocation and uptake of endotoxin inducing hepatic and systemic inflammation. CONCLUSIONS Manipulation of the gut microbiota with diet, probiotics or faecal microbiota transplantation to promote the growth of "healthy" bacteria may ameliorate the dysbiosis and alter prognosis.
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Affiliation(s)
- C A Woodhouse
- Institute of Liver Studies and Transplantation, King's College London School of Medicine at King's College Hospital, London, UK
| | - V C Patel
- Institute of Liver Studies and Transplantation, King's College London School of Medicine at King's College Hospital, London, UK
| | - A Singanayagam
- Institute of Liver Studies and Transplantation, King's College London School of Medicine at King's College Hospital, London, UK
| | - D L Shawcross
- Institute of Liver Studies and Transplantation, King's College London School of Medicine at King's College Hospital, London, UK
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40
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Witt AM, Larsen FS, Bjerring PN. Accumulation of lactate in the rat brain during hyperammonaemia is not associated with impaired mitochondrial respiratory capacity. Metab Brain Dis 2017; 32:461-470. [PMID: 27928693 DOI: 10.1007/s11011-016-9934-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 11/29/2016] [Indexed: 01/27/2023]
Abstract
In acute liver failure (ALF) cerebral oedema and high intracranial pressure (ICP) are potentially deadly complications. Astrocytes cultured in ammonia have shown mitochondrial dysfunction and in rat models of liver failure, de novo lactate production in the brain has been observed and has led to a hypothesis of compromised brain metabolism during ALF. In contrast, normal lactate levels are found in cerebral microdialysate of ALF patients and the oxygen: glucose ratio of cerebral metabolic rates remains normal. To investigate this inconsistency we studied the mitochondrial function in brain tissue with respirometry in animal models of hyperammonaemia. Wistar rats with systemic inflammation induced by lipopolysaccharide or liver insufficiency induced by 90% hepatectomy were given ammonium or sodium acetate for 120 min. A cerebral cortex homogenate was studied with respirometry and substrates of the citric acid cycle, uncouplers and inhibitors of the mitochondrial complexes were successively added to investigate the mitochondrial function in detail. In a separate dose-response experiment cortex from healthy rats was incubated for 120 min in ammonium acetate in concentrations up to 80 mM prior to respirometry. Hyperammonaemia was associated with elevated ICP and increased tissue lactate concentration. No difference between groups was found in total respiratory capacity or the function of individual mitochondrial complexes. Ammonium in concentrations of 40 and 80 mM reduced the respiratory capacity in vitro. In conclusion, acute hyperammonaemia leads to elevated ICP and cerebral lactate accumulation. We found no indications of impaired oxidative metabolism in vivo but only in vitro at extreme concentrations of ammonium.
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Affiliation(s)
- Anne Møller Witt
- Department of Hepatology, Rigshospitalet, DK-2100, Copenhagen, Denmark
| | - Fin Stolze Larsen
- Department of Hepatology, Rigshospitalet, DK-2100, Copenhagen, Denmark
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Li Y, Liu H, Zeng W, Wei J. Edaravone protects against hyperosmolarity-induced oxidative stress and apoptosis in primary human corneal epithelial cells. PLoS One 2017; 12:e0174437. [PMID: 28346481 PMCID: PMC5367814 DOI: 10.1371/journal.pone.0174437] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 03/09/2017] [Indexed: 02/05/2023] Open
Abstract
An increase in the osmolarity of tears induced by excessive evaporation of the aqueous tear phase is a major pathological mechanism behind dry eye. Exposure of epithelial cells on the surface of the human eye to hyperosmolarity leads to oxidative stress, mitochondrial dysfunction, and apoptosis. Edaravone, a hydroxyl radical scavenging agent, is clinically used to reduce neuronal damage following ischemic stroke. In this study, we found that treatment with hyperosmotic media at 400 and 450 mOsM increased the levels of ROS and mitochondrial oxidative damage, which were ameliorated by edaravone treatment in a dose-dependent manner. We also found that edaravone could improve mitochondrial function in HCEpiCs by increasing the levels of ATP and mitochondrial membrane potential. MTT and LDH assays indicated that edaravone could attenuate hyperosmolarity-induced cell death. It was found that edaravone prevented apoptosis by decreasing the level of cleaved caspase-3, and attenuating the release of cytochrome C. Mechanistically, we found that edaravone augmented the expression of Nrf2 and its target genes, such as HO-1, GPx-1, and GCLC.
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Affiliation(s)
- Yanwei Li
- Department of Ophthalmology, The First Affiliated Hospital and College of Clinical Medicine of Henan University of Science and Technology, Luoyang, China
| | - Haifeng Liu
- Department of Ophthalmology, The Third Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
| | - Wei Zeng
- Department of Otorhinolaryngology Head and Neck Surgery, The First Affiliated Hospital and College of Clinical Medicine of Henan University of Science and Technology, Luoyang, China
| | - Jing Wei
- Department of Ophthalmology, The First Affiliated Hospital and College of Clinical Medicine of Henan University of Science and Technology, Luoyang, China
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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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Patel VC, White H, Støy S, Bajaj JS, Shawcross DL. Clinical science workshop: targeting the gut-liver-brain axis. Metab Brain Dis 2016; 31:1327-1337. [PMID: 26446022 DOI: 10.1007/s11011-015-9743-4] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 10/02/2015] [Indexed: 02/08/2023]
Abstract
A clinical science workshop was held at the ISHEN meeting in London on Friday 11th September 2014 with the aim of thrashing out how we might translate what we know about the central role of the gut-liver-brain axis into targets which we can use in the treatment of hepatic encephalopathy (HE). This review summarises the integral role that inter-organ ammonia metabolism plays in the pathogenesis of HE with specific discussion of the roles that the small and large intestine, liver, brain, kidney and muscle assume in ammonia and glutamine metabolism. Most recently, the salivary and gut microbiome have been shown to underpin the pathophysiological changes which culminate in HE and patients with advanced cirrhosis present with enteric dysbiosis with small bowel bacterial overgrowth and translocation of bacteria and their products across a leaky gut epithelial barrier. Resident macrophages within the liver are able to sense bacterial degradation products initiating a pro-inflammatory response within the hepatic parenchyma and release of cytokines such as tumour necrosis factor alpha (TNF-α) and interleukin-8 into the systemic circulation. The endotoxemia and systemic inflammatory response that are generated predispose both to the development of infection as well as the manifestation of covert and overt HE. Co-morbidities such as diabetes and insulin resistance, which commonly accompany cirrhosis, may promote slow gut transit, promote bacterial overgrowth and increase glutaminase activity and may need to be acknowledged in HE risk stratification assessments and therapeutic regimens. Therapies are discussed which target ammonia production, utilisation or excretion at an individual organ level, or which reduce systemic inflammation and endotoxemia which are known to exacerbate the cerebral effects of ammonia in HE. The ideal therapeutic strategy would be to use an agent that can reduce hyperammonemia and reduce systemic inflammation or perhaps to adopt a combination of therapies that can address both.
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Affiliation(s)
- Vishal C Patel
- Institute of Liver Studies, King's College London School of Medicine, King's College Hospital, King's College Hospital, Denmark Hill, London, SE5 9RS, UK
| | - Helen White
- Institute of Liver Studies, King's College London School of Medicine, King's College Hospital, King's College Hospital, Denmark Hill, London, SE5 9RS, UK
| | - Sidsel Støy
- Institute of Liver Studies, King's College London School of Medicine, King's College Hospital, King's College Hospital, Denmark Hill, London, SE5 9RS, UK
| | - Jasmohan S Bajaj
- McGuire VA Medical Center, Virginia Commonwealth University, Richmond, VA, USA
| | - Debbie L Shawcross
- Institute of Liver Studies, King's College London School of Medicine, King's College Hospital, King's College Hospital, Denmark Hill, London, SE5 9RS, UK.
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Wright G, Swain M, Annane D, Saliba F, Samuel D, Arroyo V, DeMorrow S, Witt A. Neuroinflammation in liver disease: sessional talks from ISHEN. Metab Brain Dis 2016; 31:1339-1354. [PMID: 27726053 DOI: 10.1007/s11011-016-9918-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Accepted: 09/27/2016] [Indexed: 12/20/2022]
Abstract
At the recent ISHEN ('International Symposium of Hepatic Encephalopathy & Nitrogen Metabolism') conference in London, a whole session was dedicated to our increasing awareness of the importance of inflammation in the brain - termed 'neuroinflammation', in the development of Hepatic Encephalopathy (HE) - the neurological manifestations of advanced liver disease. In this review our ISHEN speakers further discuss the content of their sessional presentations and more broadly we discuss our understanding of the role of neuroinflammation in HE pathogenesis.
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Affiliation(s)
- Gavin Wright
- Gastroenterology Department, Basildon & Thurrock University Hospitals, Basildon, UK.
- Hepatology and Hepatobiliary Medicine, The Royal Free Hospital, Pond Street, London, NW3 2QG, UK.
- University College London, Gower Street, London, WC1E 6BT, UK.
| | - Mark Swain
- Division of Gastroenterology and Hepatology, University of Calgary, Calgary, Canada
| | - Djillali Annane
- INSERM CIC IT 805, CHU Paris IdF Ouest - Hôpital Raymond Poincaré, 104 boulevard Raymond Poincaré, 92380, Garches, France
| | - Faouzi Saliba
- Centre Hépato-Biliaire, Hôpital Paul Brousse, 12, avenue Paul vaillant Couturier, 94800, Villejuif, France
| | - Didier Samuel
- GHU Paris-Sud - Hôpital Paul Brousse, 12 avenue Paul Vaillant-Couturier, 94804, Villejuif Cedex, France
| | - Vicente Arroyo
- Liver Unit, Instiute of Digestive and Metabolic Diseases, Hopsital Clinic, University of Barcelona, Barcelona, Spain
| | - Sharon DeMorrow
- Department of Internal Medicine, Central Texas Veterans Healthcare System, VA Bld 205, 1901 South 1st Street, Temple, TX, 76504, USA
| | - Anne Witt
- Departement of Hepatology, Rigshospitalet, Blegdamsvej 9, 2100 København Ø, Copenhagen, Denmark
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Abusneina A, Gauthier ER. Ammonium ions improve the survival of glutamine-starved hybridoma cells. Cell Biosci 2016; 6:23. [PMID: 27087916 PMCID: PMC4832542 DOI: 10.1186/s13578-016-0092-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Accepted: 04/04/2016] [Indexed: 12/17/2022] Open
Abstract
Background As a consequence of a reprogrammed metabolism, cancer cells are dependent on the amino acid l-glutamine for their survival, a phenomenon that currently forms the basis for the generation of new, cancer-specific therapies. In this paper, we report on the role which ammonium ions, a product of glutaminolysis, play on the survival of l-glutamine-deprived Sp2/0-Ag14 mouse hybridoma cells. Results The supplementation of l-glutamine-starved Sp2/0-Ag14 cell cultures with either ammonium acetate or ammonium chloride resulted in a significant increase in viability. This effect did not depend on the ability of cells to synthesize l-glutamine, and was not affected by the co-supplementation with α-ketoglutarate. When we examined the effect of ammonium acetate and ammonium chloride on the induction of apoptosis by glutamine deprivation, we found that ammonium salts did not prevent caspase-3 activation or cytochrome c leakage, indicating that they did not act by modulating core apoptotic processes. However, both ammonium acetate and ammonium chloride caused a significant reduction in the number of l-glutamine-starved cells exhibiting apoptotic nuclear fragmentation and/or condensation. Conclusion All together, our results show that ammonium ions promote the survival of l-glutamine-deprived Sp2/0-Ag14 cells and modulate late-apoptotic events. These findings highlight the complexity of the modulation of cell survival by l-glutamine, and suggest that targeting survival-signaling pathways modulated by ammonium ions should be examined as a potential anti-cancer strategy.
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Affiliation(s)
| | - Eric R Gauthier
- Biomolecular Sciences, Laurentian University, Sudbury, ON P3E 2C6 Canada ; Department of Chemistry and Biochemistry, Laurentian University, Sudbury, ON P3E 2C6 Canada ; Department of Biology, Laurentian University, Sudbury, ON P3E 2C6 Canada
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Ammonia-induced miRNA expression changes in cultured rat astrocytes. Sci Rep 2016; 6:18493. [PMID: 26755400 PMCID: PMC4709596 DOI: 10.1038/srep18493] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 11/19/2015] [Indexed: 12/20/2022] Open
Abstract
Hepatic encephalopathy is a neuropsychiatric syndrome evolving from cerebral osmotic disturbances and oxidative/nitrosative stress. Ammonia, the main toxin of hepatic encephalopathy, triggers astrocyte senescence in an oxidative stress-dependent way. As miRNAs are critically involved in cell cycle regulation and their expression may be regulated by oxidative stress, we analysed, whether astrocyte senescence is a consequence of ammonia-induced miRNA expression changes. Using a combined miRNA and gene microarray approach, 43 miRNA species which were downregulated and 142 genes which were upregulated by NH4Cl (5 mmol/l, 48 h) in cultured rat astrocytes were found. Ammonia-induced miRNA and gene expression changes were validated by qPCR and 43 potential miRNA target genes, including HO-1, were identified by matching upregulated mRNA species with predicted targets of miRNA species downregulated by ammonia. Inhibition of HO-1 targeting miRNAs which were downregulated by NH4Cl strongly upregulated HO-1 mRNA and protein levels and inhibited astrocyte proliferation in a HO-1-dependent way. Preventing ammonia-induced upregulation of HO-1 by taurine (5 mmol/l) as well as blocking HO-1 activity by tin-protoporphyrine IX fully prevented ammonia-induced proliferation inhibition and senescence. The data suggest that ammonia induces astrocyte senescence through NADPH oxidase-dependent downregulation of HO-1 targeting miRNAs and concomitant upregulation of HO-1 at both mRNA and protein level.
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Wang F, Du T, Liang C, Verkhratsky A, Peng L. Ammonium increases Ca(2+) signalling and upregulates expression of Cav1.2 gene in astrocytes in primary cultures and in the in vivo brain. Acta Physiol (Oxf) 2015; 214:261-74. [PMID: 25846713 DOI: 10.1111/apha.12500] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2015] [Revised: 03/16/2015] [Accepted: 03/27/2015] [Indexed: 12/12/2022]
Abstract
AIM The primary aim of this study was to identify the effects of hyperammonaemia on functional expression of Cav1.2 L-type Ca(2+) channels in astroglia. METHODS Primary cultures of mouse astrocytes were used to study effects of chronic treatment (1-5 days) with ammonium chloride, at 1, 3 and 5 mm on depolarization-induced increases in free cytosolic Ca(2+) concentration ([Ca(2+)]i , measured with Fura-2 based microfluorimetry) in control conditions and following treatment with the L-type Ca(2+) channel inhibitor, nifedipine, or with ryanodine receptor inhibitor, ryanodine. Expression of Cav1.2 mRNA was identified with RT-PCR, whereas protein content was determined by Western blotting. Sustained hyperammonaemia in vivo was induced by daily injections of urease (33 units kg body weight(-1), i.p.) for 3 days. RESULTS Depolarization-induced [Ca(2+)]i transients sensitive to nifedipine (peak of the response) and to ryanodine (plateau phase) were significantly increased in astrocytes chronically exposed to ammonium. The ammonium-induced increase in Ca(2+) influx in astrocytes resulted from an upregulation of Cav1.2 channel's expression detected at mRNA and protein levels. Increase in Cav1.2 expression was prevented by ouabain antagonist canrenone. Similar upregulation of Cav1.2 gene expression was found in the brains of adult mice subjected to intraperitoneal injection of urease. In transgenic mice tagged with an astrocyte-specific or neurone-specific markers and treated with intraperitoneal injections of urease, the fluorescence-activated cell sorting of neurones and astrocytes demonstrated that Cav1.2 mRNA expression was upregulated in astrocytes, but not in neurones. CONCLUSIONS Ammonium-induced deregulation of astroglial Ca(2+) signalling, is, in part, associated with upregulation of Cav1.2 L-type calcium channels.
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Affiliation(s)
- F. Wang
- Laboratory of Brain Metabolic Diseases; Institute of Metabolic Disease Research and Drug Development; China Medical University; Shenyang China
| | - T. Du
- Laboratory of Brain Metabolic Diseases; Institute of Metabolic Disease Research and Drug Development; China Medical University; Shenyang China
| | - C. Liang
- Laboratory of Brain Metabolic Diseases; Institute of Metabolic Disease Research and Drug Development; China Medical University; Shenyang China
| | - A. Verkhratsky
- Faculty of Life Science; The University of Manchester; Manchester UK
- Achucarro Center for Neuroscience; IKERBASQUE; Basque Foundation for Science; Bilbao Spain
- University of Nizhny Novgorod; Nizhny Novgorod Russia
| | - L. Peng
- Laboratory of Brain Metabolic Diseases; Institute of Metabolic Disease Research and Drug Development; China Medical University; Shenyang China
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Butterworth RF. Pathogenesis of hepatic encephalopathy and brain edema in acute liver failure. J Clin Exp Hepatol 2015; 5:S96-S103. [PMID: 26041966 PMCID: PMC4442857 DOI: 10.1016/j.jceh.2014.02.004] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Accepted: 02/07/2014] [Indexed: 12/12/2022] Open
Abstract
Neuropathologic investigations in acute liver failure (ALF) reveal significant alterations to neuroglia consisting of swelling of astrocytes leading to cytotoxic brain edema and intracranial hypertension as well as activation of microglia indicative of a central neuroinflammatory response. Increased arterial ammonia concentrations in patients with ALF are predictors of patients at risk for the development of brain herniation. Molecular and spectroscopic techniques in ALF reveal alterations in expression of an array of genes coding for neuroglial proteins involved in cell volume regulation and mitochondrial function as well as in the transport of neurotransmitter amino acids and in the synthesis of pro-inflammatory cytokines. Liver-brain pro-inflammatory signaling mechanisms involving transduction of systemically-derived cytokines, ammonia neurotoxicity and exposure to increased brain lactate have been proposed. Mild hypothermia and N-Acetyl cysteine have both hepato-protective and neuro-protective properties in ALF. Potentially effective anti-inflammatory agents aimed at control of encephalopathy and brain edema in ALF include etanercept and the antibiotic minocycline, a potent inhibitor of microglial activation. Translation of these potentially-interesting findings to the clinic is anxiously awaited.
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Key Words
- ALF, acute liver failure
- ATP, adenosine triphosphate
- BBB, blood-brain barrier
- CCL2, chemokine ligand-2
- CMRO2, cerebral metabolic rate for oxygen
- CNS, central nervous system
- EEG, electroencephalography
- GABA, gamma-aminobutyric acid
- GFAP, glial fibrillary acidic protein
- IgG, immunoglobulin
- MRS, magnetic resonance spectroscopy
- NAC, N-Acetyl cysteine
- NMDA, N-methyl-d-aspartate
- SIRS, systemic inflammatory response syndrome
- SNATs, several neutral amino acid transport systems
- TLP, translocator protein
- TNFα, tumor necrosis factor alpha
- acute liver failure
- hepatic encephalopathy
- intracranial hypertension
- microglial activation
- neuroinflammation
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Affiliation(s)
- Roger F. Butterworth
- Neuroscience Research Unit, Hopital St-Luc (CHUM) and Department of Medicine, University of Montreal, Montreal, QC H2W 3J4, Canada,Address for correspondence: Roger F. Butterworth, Neuroscience Research Unit, Hospital St-Luc (CHUM) and Department of Medicine, University of Montreal, 1058 St Denis, Montreal, QC H2W 3J4, Canada. Tel.: +1 902 929 2470.
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Aldridge DR, Tranah EJ, Shawcross DL. Pathogenesis of hepatic encephalopathy: role of ammonia and systemic inflammation. J Clin Exp Hepatol 2015; 5:S7-S20. [PMID: 26041962 PMCID: PMC4442852 DOI: 10.1016/j.jceh.2014.06.004] [Citation(s) in RCA: 193] [Impact Index Per Article: 21.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/09/2013] [Accepted: 06/05/2014] [Indexed: 12/12/2022] Open
Abstract
The syndrome we refer to as Hepatic Encephalopathy (HE) was first characterized by a team of Nobel Prize winning physiologists led by Pavlov and Nencki at the Imperial Institute of Experimental Medicine in Russia in the 1890's. This focused upon the key observation that performing a portocaval shunt, which bypassed nitrogen-rich blood away from the liver, induced elevated blood and brain ammonia concentrations in association with profound neurobehavioral changes. There exists however a spectrum of metabolic encephalopathies attributable to a variety (or even absence) of liver hepatocellular dysfunctions and it is this spectrum rather than a single disease entity that has come to be defined as HE. Differences in the underlying pathophysiology, treatment responses and outcomes can therefore be highly variable between acute and chronic HE. The term also fails to articulate quite how systemic the syndrome of HE can be and how it can be influenced by the gastrointestinal, renal, nervous, or immune systems without any change in background liver function. The pathogenesis of HE therefore encapsulates a complex network of interdependent organ systems which as yet remain poorly characterized. There is nonetheless a growing recognition that there is a complex but influential synergistic relationship between ammonia, inflammation (sterile and non-sterile) and oxidative stress in the pathogenesis HE which develops in an environment of functional immunoparesis in patients with liver dysfunction. Therapeutic strategies are thus moving further away from the traditional specialty of hepatology and more towards novel immune and inflammatory targets which will be discussed in this review.
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Key Words
- ATP, adenosine triphosphate
- AoCLF, acute-on-chronic liver failure
- BBB, blood–brain barrier
- CBF, cerebral blood flow
- CNS, central nervous system
- GS, glutamine synthetase
- HE, hepatic encephalopathy
- ICH, intracranial hypertension
- MHE, minimal hepatic encephalopathy
- MPT, mitochondrial permeability transition
- PAG, phosphate-activated glutaminase
- PTP, permeability transition pore
- TLR, toll-like receptor
- ammonia
- hepatic encephalopathy
- iNOS, inducible nitric oxide synthase
- infection
- inflammation
- systemic inflammatory response syndrome
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Affiliation(s)
| | | | - Debbie L. Shawcross
- Institute of Liver Studies, King's College London School of Medicine at King's College Hospital, King's College Hospital, Denmark Hill, London SE5 9RS, United Kingdom
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Chronotherapeutic effect of fisetin on expression of urea cycle enzymes and inflammatory markers in hyperammonaemic rats. Pharmacol Rep 2014; 66:1037-42. [DOI: 10.1016/j.pharep.2014.06.018] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2013] [Revised: 06/05/2014] [Accepted: 06/25/2014] [Indexed: 11/19/2022]
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