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Anand AC, Acharya SK. The Story of Ammonia in Liver Disease: An Unraveling Continuum. J Clin Exp Hepatol 2024; 14:101361. [PMID: 38444405 PMCID: PMC10910335 DOI: 10.1016/j.jceh.2024.101361] [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: 12/10/2023] [Accepted: 02/03/2024] [Indexed: 03/07/2024] Open
Abstract
Hyperammonemia and liver disease are closely linked. Most of the ammonia in our body is produced by transamination and deamination activities involving amino acid, purine, pyrimidines, and biogenic amines, and from the intestine by bacterial splitting of urea. The only way of excretion from the body is by hepatic conversion of ammonia to urea. Hyperammonemia is associated with widespread toxicities such as cerebral edema, hepatic encephalopathy, immune dysfunction, promoting fibrosis, and carcinogenesis. Over the past two decades, it has been increasingly utilized for prognostication of cirrhosis, acute liver failure as well as acute on chronic liver failure. The laboratory assessment of hyperammonemia has certain limitations, despite which its value in the assessment of various forms of liver disease cannot be negated. It may soon become an important tool to make therapeutic decisions about the use of prophylactic and definitive treatment in various forms of liver disease.
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Balzano T. Active Clinical Trials in Hepatic Encephalopathy: Something Old, Something New and Something Borrowed. Neurochem Res 2023:10.1007/s11064-023-03916-w. [PMID: 36977964 PMCID: PMC10047473 DOI: 10.1007/s11064-023-03916-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 02/28/2023] [Accepted: 03/17/2023] [Indexed: 03/30/2023]
Abstract
Hepatic encephalopathy (HE) is a potentially reversible neurocognitive syndrome that occurs in patients with acute or chronic liver disease. Currently, most of the therapies for HE aim to reduce ammonia production or increase its elimination. To date, only two agents have been approved as treatments for HE: lactulose and rifaximin. Many other drugs have also been used, but data to support their use are limited, preliminary or lacking. The aim of this review is to provide an overview and discussion of the current development of treatments for HE. Data from ongoing clinical trials in HE were obtained from the ClinicalTrials.gov website, and a breakdown analysis of studies that were active on August 19th, 2022, was performed. Seventeen registered and ongoing clinical trials for therapeutics targeting HE were identified. More than 75% of these agents are in phase II (41.2%) or in phase III (34.7%). Among them, there are many old acquaintances in the field, such as lactulose and rifaximin, some new entries such as fecal microbiota transplantation and equine anti-thymocyte globulin, an immunosuppressive agent, but also some therapies borrowed from other conditions, such as rifamycin SV MMX and nitazoxanide, two antimicrobial agents FDA approved for the treatment of some types of diarrheas or VE303 and RBX7455, two microbiome restoration therapies, currently used as treatment of high-risk Clostridioides difficile infections. If working, some of these drugs could soon be used as valid alternatives to current therapies when ineffective or be approved as novel therapeutic approaches to improve the quality of life of HE patients.
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Affiliation(s)
- Tiziano Balzano
- HM CINAC (Centro Integral de Neurociencias Abarca Campal), Hospital Universitario HM Puerta del Sur, HM Hospitales, Madrid, Spain.
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Understanding the Role of the Gut Microbiome and Microbial Metabolites in Non-Alcoholic Fatty Liver Disease: Current Evidence and Perspectives. Biomolecules 2021; 12:biom12010056. [PMID: 35053205 PMCID: PMC8774162 DOI: 10.3390/biom12010056] [Citation(s) in RCA: 95] [Impact Index Per Article: 31.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2021] [Revised: 12/24/2021] [Accepted: 12/30/2021] [Indexed: 12/11/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide. NAFLD begins as a relatively benign hepatic steatosis which can evolve to non-alcoholic steatohepatitis (NASH); the risk of cirrhosis and hepatocellular carcinoma (HCC) increases when fibrosis is present. NAFLD represents a complex process implicating numerous factors—genetic, metabolic, and dietary—intertwined in a multi-hit etiopathogenetic model. Recent data have highlighted the role of gut dysbiosis, which may render the bowel more permeable, leading to increased free fatty acid absorption, bacterial migration, and a parallel release of toxic bacterial products, lipopolysaccharide (LPS), and proinflammatory cytokines that initiate and sustain inflammation. Although gut dysbiosis is present in each disease stage, there is currently no single microbial signature to distinguish or predict which patients will evolve from NAFLD to NASH and HCC. Using 16S rRNA sequencing, the majority of patients with NAFLD/NASH exhibit increased numbers of Bacteroidetes and differences in the presence of Firmicutes, resulting in a decreased F/B ratio in most studies. They also present an increased proportion of species belonging to Clostridium, Anaerobacter, Streptococcus, Escherichia, and Lactobacillus, whereas Oscillibacter, Flavonifaractor, Odoribacter, and Alistipes spp. are less prominent. In comparison to healthy controls, patients with NASH show a higher abundance of Proteobacteria, Enterobacteriaceae, and Escherichia spp., while Faecalibacterium prausnitzii and Akkermansia muciniphila are diminished. Children with NAFLD/NASH have a decreased proportion of Oscillospira spp. accompanied by an elevated proportion of Dorea, Blautia, Prevotella copri, and Ruminococcus spp. Gut microbiota composition may vary between population groups and different stages of NAFLD, making any conclusive or causative claims about gut microbiota profiles in NAFLD patients challenging. Moreover, various metabolites may be involved in the pathogenesis of NAFLD, such as short-chain fatty acids, lipopolysaccharide, bile acids, choline and trimethylamine-N-oxide, and ammonia. In this review, we summarize the role of the gut microbiome and metabolites in NAFLD pathogenesis, and we discuss potential preventive and therapeutic interventions related to the gut microbiome, such as the administration of probiotics, prebiotics, synbiotics, antibiotics, and bacteriophages, as well as the contribution of bariatric surgery and fecal microbiota transplantation in the therapeutic armamentarium against NAFLD. Larger and longer-term prospective studies, including well-defined cohorts as well as a multi-omics approach, are required to better identify the associations between the gut microbiome, microbial metabolites, and NAFLD occurrence and progression.
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The Cerebral Effect of Ammonia in Brain Aging: Blood-Brain Barrier Breakdown, Mitochondrial Dysfunction, and Neuroinflammation. J Clin Med 2021; 10:jcm10132773. [PMID: 34202669 PMCID: PMC8268635 DOI: 10.3390/jcm10132773] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 06/23/2021] [Accepted: 06/23/2021] [Indexed: 12/14/2022] Open
Abstract
Aging occurs along with multiple pathological problems in various organs. The aged brain, especially, shows a reduction in brain mass, neuronal cell death, energy dysregulation, and memory loss. Brain aging is influenced by altered metabolites both in the systemic blood circulation and the central nervous system (CNS). High levels of ammonia, a natural by-product produced in the body, have been reported as contributing to inflammatory responses, energy metabolism, and synaptic function, leading to memory function in CNS. Ammonia levels in the brain also increase as a consequence of the aging process, ultimately leading to neuropathological problems in the CNS. Although many researchers have demonstrated that the level of ammonia in the body alters with age and results in diverse pathological alterations, the definitive relationship between ammonia and the aged brain is not yet clear. Thus, we review the current body of evidence related to the roles of ammonia in the aged brain. On the basis of this, we hypothesize that the modulation of ammonia level in the CNS may be a critical clinical point to attenuate neuropathological alterations associated with aging.
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Ochoa-Sanchez R, Oliveira MM, Tremblay M, Petrazzo G, Pant A, Bosoi CR, Perreault M, Querbes W, Kurtz CB, Rose CF. Genetically engineered E. coli Nissle attenuates hyperammonemia and prevents memory impairment in bile-duct ligated rats. Liver Int 2021; 41:1020-1032. [PMID: 33548108 DOI: 10.1111/liv.14815] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 12/30/2020] [Accepted: 01/28/2021] [Indexed: 12/12/2022]
Abstract
UNLABELLED Hyperammonemia associated with chronic liver disease (CLD) is implicated in the pathogenesis of hepatic encephalopathy (HE). The gut is a major source of ammonia production that contributes to hyperammonemia in CLD and HE and remains the primary therapeutic target for lowering hyperammonemia. As an ammonia-lowering strategy, Escherichia coli Nissle 1917 bacterium was genetically modified to consume and convert ammonia to arginine (S-ARG). S-ARG was further modified to additionally synthesize butyrate (S-ARG + BUT). Both strains were evaluated in bile-duct ligated (BDL) rats; experimental model of CLD and HE. METHODS One-week post-surgery, BDLs received non-modified EcN (EcN), S-ARG, S-ARG + BUT (3x1011 CFU/day) or vehicle until sacrifice at 3 or 5 weeks. Plasma (ammonia/pro-inflammatory/liver function), liver fibrosis (hydroxyproline), liver mRNA (pro-inflammatory/fibrogenic/anti-apoptotic) and colon mRNA (pro-inflammatory) biomarkers were measured post-sacrifice. Memory, motor-coordination, muscle-strength and locomotion were assessed at 5 weeks. RESULTS In BDL-Veh rats, hyperammonemia developed at 3 and further increased at 5 weeks. This rise was prevented by S-ARG and S-ARG + BUT, whereas EcN was ineffective. Memory impairment was prevented only in S-ARG + BUT vs BDL-Veh. Systemic inflammation (IL-10/MCP-1/endotoxin) increased at 3 and 5 weeks in BDL-Veh. S-ARG + BUT attenuated inflammation at both timepoints (except 5-week endotoxin) vs BDL-Veh, whereas S-ARG only attenuated IP-10 and MCP-1 at 3 weeks. Circulating ALT/AST/ALP/GGT/albumin/bilirubin and gene expression of liver function markers (IL-10/IL-6/IL-1β/TGF-β/α-SMA/collagen-1α1/Bcl-2) were not normalized by either strain. Colonic mRNA (TNF-α/IL-1β/occludin) markers were attenuated by synthetic strains at both timepoints vs BDL-Veh. CONCLUSION S-ARG and S-ARG + BUT attenuated hyperammonemia, with S-ARG + BUT additional memory protection likely due to greater anti-inflammatory effect. These innovative strategies, particularly S-ARG + BUT, have potential to prevent HE.
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Affiliation(s)
| | - Mariana M Oliveira
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Canada
| | - Mélanie Tremblay
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Canada
| | - Grégory Petrazzo
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Canada
| | | | - Cristina R Bosoi
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Canada
| | | | | | | | - Christopher F Rose
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Canada
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Cognitive Dysfunction in Non-Alcoholic Fatty Liver Disease-Current Knowledge, Mechanisms and Perspectives. J Clin Med 2021; 10:jcm10040673. [PMID: 33572481 PMCID: PMC7916374 DOI: 10.3390/jcm10040673] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/29/2021] [Accepted: 01/31/2021] [Indexed: 12/11/2022] Open
Abstract
Non-alcoholic fatty liver disease (NAFLD) has emerged as the hepatic component of the metabolic syndrome and now seemingly affects one-fourth of the world population. Features associated with NAFLD and the metabolic syndrome have frequently been linked to cognitive dysfunction, i.e. systemic inflammation, vascular dysfunction, and sleep apnoea. However, emerging evidence suggests that NAFLD may be a cause of cognitive dysfunction independent of these factors. NAFLD in addition exhibits dysbiosis of the gut microbiota and impaired urea cycle function, favouring systemic ammonia accumulation and further promotes systemic inflammation. Such disruption of the gut–liver–brain axis is essential in the pathogenesis of hepatic encephalopathy, the neuropsychiatric syndrome associated with progressive liver disease. Considering the growing burden of NAFLD, the morbidity from cognitive impairment is expected to have huge societal and economic impact. The present paper provides a review of the available evidence for cognitive dysfunction in NAFLD and outlines its possible mechanisms. Moreover, the clinical challenges of characterizing and diagnosing cognitive dysfunction in NAFLD are discussed.
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Zhao L, Walline JH, Gao Y, Lu X, Yu S, Ge Z, Zhu H, Li Y. Prognostic Role of Ammonia in Critical Care Patients Without Known Hepatic Disease. Front Med (Lausanne) 2020; 7:589825. [PMID: 33195354 PMCID: PMC7642587 DOI: 10.3389/fmed.2020.589825] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 09/25/2020] [Indexed: 01/09/2023] Open
Abstract
Background and Aims: Hyperammonemia usually develops because of hepatic disease, but it may occur in patients with non-hepatic hyperammonemia (NHH). But, studies on the prognosis and possible risk factors of this disorder are lacking. The aim of this study was to find possible prognostic and risk factors for NHH in critically ill patients. Methods: Data were extracted from MIMIC III Database. Survival was analyzed by the Kaplan-Meier method. Univariate and multivariate analyses were performed to identify prognostic factors. Results: Valproic acid, carbamazepine, corticosteroids, recent orthopedic surgery, epilepsy, disorders of urea cycle metabolism, and obesity were found to be risk factors for NHH. Patients in the hyperammonemia group had a higher 30 day mortality than those in the non-hyperammonemia group. After final regression analysis, ammonia was found to be independent predictors of mortality. Conclusion: Ammonia was an independent prognostic predictor of 30 day mortality for critical care patients without liver disease.
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Affiliation(s)
- Lina Zhao
- Emergency Department, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Joseph Harold Walline
- Accident and Emergency Medicine Academic Unit, Prince of Wales Hospital, The Chinese University of Hong Kong, Hong Kong, China
| | - Yanxia Gao
- Emergency Department, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China
| | - Xin Lu
- Emergency Department, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Shiyuan Yu
- Emergency Department, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Zengzheng Ge
- Emergency Department, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Huadong Zhu
- Emergency Department, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
| | - Yi Li
- Emergency Department, Peking Union Medical College Hospital, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China
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Balzano T, Dadsetan S, Forteza J, Cabrera-Pastor A, Taoro-Gonzalez L, Malaguarnera M, Gil-Perotin S, Cubas-Nuñez L, Casanova B, Castro-Quintas A, Ponce-Mora A, Arenas YM, Leone P, Erceg S, Llansola M, Felipo V. Chronic hyperammonemia induces peripheral inflammation that leads to cognitive impairment in rats: Reversed by anti-TNF-α treatment. J Hepatol 2020; 73:582-592. [PMID: 30654069 DOI: 10.1016/j.jhep.2019.01.008] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 01/03/2019] [Accepted: 01/04/2019] [Indexed: 01/04/2023]
Abstract
BACKGROUND & AIMS Chronic hyperammonemia induces neuroinflammation which mediates cognitive impairment. How hyperammonemia induces neuroinflammation remains unclear. We aimed to assess whether: chronic hyperammonemia induces peripheral inflammation, and whether this then contributes to neuroinflammation, altered neurotransmission and impaired spatial learning - before assessing whether this neuroinflammation and impairment is reversible following hyperammonemia elimination or treatment of peripheral inflammation with anti-TNF-α. METHODS Chronic hyperammonemia was induced by feeding rats an ammonia-containing diet. Peripheral inflammation was analyzed by measuring PGE2, TNF-α, IL-6 and IL-10. We tested whether chronic anti-TNF-α treatment improves peripheral inflammation, neuroinflammation, membrane expression of glutamate receptors in the hippocampus and spatial learning. RESULTS Hyperammonemic rats show a rapid and reversible induction of peripheral inflammation, with increased pro-inflammatory PGE2, TNF-α and IL-6, followed at around 10 days by reduced anti-inflammatory IL-10. Peripheral anti-TNF-α treatment prevents peripheral inflammation induction and the increase in IL-1b and TNF-α and microglia activation in hippocampus of the rats, which remain hyperammonemic. This is associated with prevention of the altered membrane expression of glutamate receptors and of the impairment of spatial memory assessed in the radial and Morris water mazes. CONCLUSIONS This report unveils a new mechanism by which chronic hyperammonemia induces neurological alterations: induction of peripheral inflammation. This suggests that reducing peripheral inflammation by safe procedures would improve cognitive function in patients with minimal hepatic encephalopathy. LAY SUMMARY This article unveils a new mechanism by which chronic hyperammonemia induces cognitive impairment in rats: chronic hyperammonemia per se induces peripheral inflammation, which mediates many of its effects on the brain, including induction of neuroinflammation, which alters neurotransmission, leading to cognitive impairment. It is also shown that reducing peripheral inflammation by treating rats with anti-TNF-α, which does not cross the blood-brain barrier, prevents hyperammonemia-induced neuroinflammation, alterations in neurotransmission and cognitive impairment.
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Affiliation(s)
- Tiziano Balzano
- Laboratory of Neurobiology, Centro Investigación Príncipe Felipe, Valencia, Spain
| | - Sherry Dadsetan
- Laboratory of Neurobiology, Centro Investigación Príncipe Felipe, Valencia, Spain
| | - Jerónimo Forteza
- Instituto Valenciano de Patología, Unidad Mixta de Patología Molecular, Centro Investigación Príncipe Felipe/Universidad Católica de Valencia Valencia, Spain
| | | | - Lucas Taoro-Gonzalez
- Laboratory of Neurobiology, Centro Investigación Príncipe Felipe, Valencia, Spain
| | - Michele Malaguarnera
- Laboratory of Neurobiology, Centro Investigación Príncipe Felipe, Valencia, Spain
| | - Sara Gil-Perotin
- Multiple Sclerosis and Neuroimmunology Research Group, Fundación para la Investigación La Fe, Valencia, Spain; Neurology Department, Hospital Universitario y Politécnico La Fe, 46026, Valencia, Spain
| | - Laura Cubas-Nuñez
- Multiple Sclerosis and Neuroimmunology Research Group, Fundación para la Investigación La Fe, Valencia, Spain
| | - Bonaventura Casanova
- Multiple Sclerosis and Neuroimmunology Research Group, Fundación para la Investigación La Fe, Valencia, Spain; Neurology Department, Hospital Universitario y Politécnico La Fe, 46026, Valencia, Spain
| | | | - Alejandro Ponce-Mora
- Laboratory of Neurobiology, Centro Investigación Príncipe Felipe, Valencia, Spain
| | - Yaiza M Arenas
- Laboratory of Neurobiology, Centro Investigación Príncipe Felipe, Valencia, Spain
| | - Paola Leone
- Laboratory of Neurobiology, Centro Investigación Príncipe Felipe, Valencia, Spain
| | - Slaven Erceg
- Stem Cells Therapies in Neurodegenerative Diseases Lab, Centro Investigación Príncipe Felipe, Valencia, Spain; National Stem Cell Bank-Valencia Node, Platform for Proteomics, Genotyping and Cell Lines, PRB3, ISCIII, Centro Investigación Príncipe Felipe, Valencia, Spain
| | - Marta Llansola
- Laboratory of Neurobiology, Centro Investigación Príncipe Felipe, Valencia, Spain
| | - Vicente Felipo
- Laboratory of Neurobiology, Centro Investigación Príncipe Felipe, Valencia, Spain.
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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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Gabbi P, Nogueira V, Haupental F, Rodrigues FS, do Nascimento PS, Barbosa S, Arend J, Furian AF, Oliveira MS, Dos Santos ARS, Royes LFF, Fighera MR. Ammonia role in glial dysfunction in methylmalonic acidemia. Toxicol Lett 2018; 295:237-248. [PMID: 30008432 DOI: 10.1016/j.toxlet.2018.06.1070] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 05/21/2018] [Accepted: 06/15/2018] [Indexed: 11/26/2022]
Abstract
Hyperammonemia is a common finding in patients with methylmalonic acidemia. However, its contribution to methylmalonate (MMA)-induced neurotoxicity is poorly understood. The aim of this study was evaluate whether an acute metabolic damage to brain during the neonatal period may disrupt cerebral development, leading to neurodevelopmental disorders, as memory deficit. Mice received a single intracerebroventricular dose of MMA and/or NH4Cl, administered 12 hs after birth. The maze tests showed that MMA and NH4Cl injected animals (21 and 40 days old) exhibited deficit in the working memory test, but not in the reference memory test. Furthermore, MMA and NH4Cl increased the levels of 2',7'-dichlorofluorescein-diacetate (DCF), TNF-α, IL-1β in the cortex, hippocampus and striatum of mice. MMA and NH4Cl also increased glial proliferation in all structures. Since the treatment of MMA and ammonia increased cytokines levels, we suggested that it might be a consequence of the glial activation induced by the acid and ammonia, leading to delay in the developing brain and contributing to behavioral alterations. However, this hypothesis is speculative in nature and more studies are needed to clarify this possibility.
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Affiliation(s)
- Patricia Gabbi
- Programa de Pós-Graduação em Farmacologia, Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde, Brazil; Laboratório de Bioquímica do Exercício, Departamento de Métodos e Técnicas Desportivas, Centro de Educação Física e Desportos, UFSM, Brazil; Departamento de Neuropsiquiatria, Centro de Ciências da Saúde, UFSM, Brazil
| | - Viviane Nogueira
- Programa de Pós-Graduação em Farmacologia, Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde, Brazil; Laboratório de Bioquímica do Exercício, Departamento de Métodos e Técnicas Desportivas, Centro de Educação Física e Desportos, UFSM, Brazil; Departamento de Neuropsiquiatria, Centro de Ciências da Saúde, UFSM, Brazil
| | - Fernanda Haupental
- Programa de Pós-Graduação em Farmacologia, Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde, Brazil; Laboratório de Bioquímica do Exercício, Departamento de Métodos e Técnicas Desportivas, Centro de Educação Física e Desportos, UFSM, Brazil; Departamento de Neuropsiquiatria, Centro de Ciências da Saúde, UFSM, Brazil
| | - Fernanda Silva Rodrigues
- Laboratório de Bioquímica do Exercício, Departamento de Métodos e Técnicas Desportivas, Centro de Educação Física e Desportos, UFSM, Brazil; Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Brazil; Departamento de Neuropsiquiatria, Centro de Ciências da Saúde, UFSM, Brazil
| | - Patricia Severo do Nascimento
- Programa de Pós-Graduação em Farmacologia, Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde, Brazil; Departamento de Ciências Morfológicas, Laboratório de Histofisiologia Comparada, UFRGS, Brazil
| | - Sílvia Barbosa
- Departamento de Ciências Morfológicas, Laboratório de Histofisiologia Comparada, UFRGS, Brazil
| | - Josi Arend
- Programa de Pós-Graduação em Farmacologia, Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde, Brazil; Laboratório de Bioquímica do Exercício, Departamento de Métodos e Técnicas Desportivas, Centro de Educação Física e Desportos, UFSM, Brazil; Departamento de Neuropsiquiatria, Centro de Ciências da Saúde, UFSM, Brazil
| | - Ana Flávia Furian
- Programa de Pós-Graduação em Farmacologia, Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde, Brazil
| | - Mauro Schneider Oliveira
- Programa de Pós-Graduação em Farmacologia, Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde, Brazil
| | - Adair Roberto Soares Dos Santos
- Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Brazil; Programa de Pós-graduação em Neurociências, Centro de Ciências Biológicas, Universidade Federal de Santa Catarina, Brazil
| | - Luiz Fernando Freire Royes
- Programa de Pós-Graduação em Farmacologia, Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde, Brazil; Laboratório de Bioquímica do Exercício, Departamento de Métodos e Técnicas Desportivas, Centro de Educação Física e Desportos, UFSM, Brazil; Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Brazil
| | - Michele Rechia Fighera
- Programa de Pós-Graduação em Farmacologia, Departamento de Fisiologia e Farmacologia, Centro de Ciências da Saúde, Brazil; Laboratório de Bioquímica do Exercício, Departamento de Métodos e Técnicas Desportivas, Centro de Educação Física e Desportos, UFSM, Brazil; Programa de Pós-Graduação em Ciências Biológicas: Bioquímica Toxicológica, Brazil; Departamento de Neuropsiquiatria, Centro de Ciências da Saúde, UFSM, Brazil.
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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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Luo M, Guo JY, Cao WK. Inflammation: A novel target of current therapies for hepatic encephalopathy in liver cirrhosis. World J Gastroenterol 2015; 21:11815-11824. [PMID: 26557005 PMCID: PMC4631979 DOI: 10.3748/wjg.v21.i41.11815] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 06/19/2015] [Accepted: 09/14/2015] [Indexed: 02/06/2023] Open
Abstract
Hepatic encephalopathy (HE) is a severe neuropsychiatric syndrome that most commonly occurs in decompensated liver cirrhosis and incorporates a spectrum of manifestations that ranges from mild cognitive impairment to coma. Although the etiology of HE is not completely understood, it is believed that multiple underlying mechanisms are involved in the pathogenesis of HE, and one of the main factors is thought to be ammonia; however, the ammonia hypothesis in the pathogenesis of HE is incomplete. Recently, it has been increasingly demonstrated that inflammation, including systemic inflammation, neuroinflammation and endotoxemia, acts in concert with ammonia in the pathogenesis of HE in cirrhotic patients. Meanwhile, a good number of studies have found that current therapies for HE, such as lactulose, rifaximin, probiotics and the molecular adsorbent recirculating system, could inhibit different types of inflammation, thereby improving the neuropsychiatric manifestations and preventing the progression of HE in cirrhotic patients. The anti-inflammatory effects of these current therapies provide a novel therapeutic approach for cirrhotic patients with HE. The purpose of this review is to describe the inflammatory mechanisms behind the etiology of HE in cirrhosis and discuss the current therapies that target the inflammatory pathogenesis of HE.
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Kimoloi S, Rashid K. Potential role of Plasmodium falciparum-derived ammonia in the pathogenesis of cerebral malaria. Front Neurosci 2015; 9:234. [PMID: 26190968 PMCID: PMC4490226 DOI: 10.3389/fnins.2015.00234] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 06/18/2015] [Indexed: 12/19/2022] Open
Abstract
Cerebral malaria (CM) is the most severe complication associated with Plasmodium falciparum infection. The exact pathogenic mechanisms leading to the development of CM remains poorly understood while the mortality rates remain high. Several potential mechanisms including mechanical obstruction of brain microvasculature, inflammation, oxidative stress, cerebral energy defects, and hemostatic dysfunction have been suggested to play a role in CM pathogenesis. However, these proposed mechanisms, even when considered together, do not fully explain the pathogenesis and clinicopathological features of human CM. This necessitates consideration of alternative pathogenic mechanisms. P. falciparum generates substantial amounts of ammonia as a catabolic by-product, but lacks detoxification mechanisms. Whether this parasite-derived ammonia plays a pathogenic role in CM is presently unknown, despite its potential to cause localized brain ammonia elevation and subsequent neurotoxic effects. This article therefore, explores and proposes a potential role of parasite-derived ammonia in the pathogenesis and neuropathology of CM. A consideration of parasite-derived ammonia as a factor in CM pathogenesis provides plausible explanations of the various features observed in CM patients including how a largely intravascular parasite can cause neuronal dysfunction. It also provides a framework for rational development and testing of novel drugs targeting the parasite's ammonia handling.
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Affiliation(s)
- Sammy Kimoloi
- Department of Medical Laboratory Sciences, Masinde Muliro University of Science and Technology Kakamega, Kenya
| | - Khalid Rashid
- Biochemistry and Molecular Biology Department, Egerton University Nakuru, Kenya
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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: 185] [Impact Index Per Article: 20.6] [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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15
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Sturgeon JP, Shawcross DL. Recent insights into the pathogenesis of hepatic encephalopathy and treatments. Expert Rev Gastroenterol Hepatol 2014; 8:83-100. [PMID: 24236755 DOI: 10.1586/17474124.2014.858598] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Hepatic encephalopathy (HE) encompasses a spectrum of neuropsychiatric disorders related to liver failure. The development of HE can have a profound impact on mortality as well as quality of life for patients and carers. Ammonia is central in the disease process contributing to alteration in neurotransmission, oxidative stress, and cerebral edema and astrocyte swelling in acute liver failure. Inflammation in the presence of ammonia coactively worsens HE. Inflammation can result from hyperammonemic responses, endotoxemia, innate immune dysfunction or concurrent infection. This review summarizes the current processes implicated in the pathogenesis of HE, as well as current and potential treatments. Treatments currently focus on reducing inflammation and/or blood ammonia levels and provide varying degrees of success. Optimization of current treatments and initial testing of novel therapies will provide the basis of improvement of care in the near future.
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Affiliation(s)
- Jonathan P Sturgeon
- Institute of Liver Studies, King's College London School of Medicine at King's College Hospital, Denmark Hill, London, SE5 9RS, UK
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16
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McGuire PJ, Lee HS, Summar ML. Infectious precipitants of acute hyperammonemia are associated with indicators of increased morbidity in patients with urea cycle disorders. J Pediatr 2013; 163:1705-1710.e1. [PMID: 24084106 PMCID: PMC3958925 DOI: 10.1016/j.jpeds.2013.08.029] [Citation(s) in RCA: 23] [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: 04/15/2013] [Revised: 07/10/2013] [Accepted: 08/14/2013] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To prospectively characterize acute hyperammonemic episodes in patients with urea cycle disorders (UCDs) in terms of precipitating factors, treatments, and use of medical resources. STUDY DESIGN This was a prospective, longitudinal observational study of hyperammonemic episodes in patients with UCD enrolled in the National Institutes of Health-sponsored Urea Cycle Disorders Consortium Longitudinal Study. An acute hyperammonemic event was defined as plasma ammonia level >100 μmol/L. Physician-reported data regarding the precipitating event and laboratory and clinical variables were recorded in a central database. RESULTS In our study population, 128 patients with UCD experienced a total of 413 hyperammonemia events. Most patients experienced between 1 and 3 (65%) or between 4 and 6 (23%) hyperammonemia events since study inception, averaging fewer than 1 event/year. The most common identifiable precipitant was infection (33%), 24% of which were upper/lower respiratory tract infections. Indicators of increased morbidity were seen with infection, including increased hospitalization rates (P = .02), longer hospital stays (+2.0 days; P = .003), and increased use of intravenous ammonia scavengers (+45%-52%; P = .003-.03). CONCLUSION Infection is the most common precipitant of acute hyperammonemia in patients with UCD and is associated with indicators of increased morbidity (ie, hospitalization rate, length of stay, and use of intravenous ammonia scavengers). These findings suggest that the catabolic and immune effects of infection may be a target for clinical intervention in inborn errors of metabolism.
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Affiliation(s)
- Peter J McGuire
- National Human Genome Research Institute, National Institutes of Health, Bethesda, MD.
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17
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Abstract
Liver failure affects brain function, leading to neurological and psychiatric alterations; such alterations are referred to as hepatic encephalopathy (HE). Early diagnosis of minimal HE reveals an unexpectedly high incidence of mild cognitive impairment and psychomotor slowing in patients with liver cirrhosis - conditions that have serious health, social and economic consequences. The mechanisms responsible for the neurological alterations in HE are beginning to emerge. New therapeutic strategies acting on specific targets in the brain (phosphodiesterase 5, type A GABA receptors, cyclooxygenase and mitogen-activated protein kinase p38) have been shown to restore cognitive and motor function in animal models of chronic HE, and NMDA receptor antagonists have been shown to increase survival in acute liver failure. This article reviews the latest studies aimed at understanding how liver failure affects brain function and potential ways to ameliorate these effects.
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Luo M, Li L, Yang EN, Dai CY, Liang SR, Cao WK. Correlation between interleukin-6 and ammonia in patients with overt hepatic encephalopathy due to cirrhosis. Clin Res Hepatol Gastroenterol 2013; 37:384-90. [PMID: 23084463 DOI: 10.1016/j.clinre.2012.08.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2012] [Revised: 07/12/2012] [Accepted: 08/08/2012] [Indexed: 02/07/2023]
Abstract
OBJECTIVE Previous studies have shown that elevated serum levels of interleukin-6 (IL-6) correlate with the severity of overt hepatic encephalopathy (OHE) in cirrhotic patients. However, the correlation between serum IL-6 levels and plasma ammonia levels in these patients remains unclear. Therefore, the present study investigated this correlation between both variables in cirrhotic patients with OHE. METHODS Fifty-five cirrhotic patients with various grades of OHE, 29 cirrhotic patients without OHE, and 30 healthy controls were recruited. Concentrations of plasma ammonia and serum IL-6 were simultaneously measured. RESULTS In cirrhotic patients with OHE, the severity of OHE, represented by the West Haven criteria, correlated with serum IL-6 levels (r=0.43, P<0.05) and plasma ammonia levels (r=0.59, P<0.05). IL-6 and ammonia were found to be significant independent predictors of OHE severity (P<0.05 for both variables). Furthermore, the severity of liver cirrhosis, determined by Child-Pugh scores, correlated with serum IL-6 levels (r=0.45, P<0.05) and plasma ammonia levels (r=0.68, P<0.05) in these patients. Moreover, there was a significant positive correlation between serum IL-6 levels and plasma ammonia levels (r=0.58, P<0.05) in cirrhotic patients with OHE, but not in patients without OHE (r=0.42, P>0.05) or healthy controls (r=0.27, P>0.05). The correlation between IL-6 and ammonia was independent of infectious precipitating factors. CONCLUSIONS The results of the present study suggest that IL-6 might be involved in the mechanism by which ammonia contributes to the pathogenesis of OHE. There is also evidence of a potential synergistic interaction between proinflammatory cytokines and ammonia in the pathogenesis of OHE.
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Affiliation(s)
- Ming Luo
- Graduate School, Tianjin Medical University, No. 81 mailbox, 22, Qixiangtai Road, Heping District, 300070 Tianjin, China.
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Coltart I, Tranah TH, Shawcross DL. Inflammation and hepatic encephalopathy. Arch Biochem Biophys 2013; 536:189-96. [PMID: 23583306 DOI: 10.1016/j.abb.2013.03.016] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2013] [Revised: 03/13/2013] [Accepted: 03/19/2013] [Indexed: 12/12/2022]
Abstract
Hepatic encephalopathy (HE) is a neuropsychiatric syndrome associated with both acute and chronic liver dysfunction, spanning a spectrum that ranges from mild neuropsychological disturbances to coma. The central role of ammonia in the pathogenesis of HE remains incontrovertible however, there is a robust evidence base indicating the important role of inflammation in exacerbating the neurological effects of HE. Inflammation can arise directly within the brain itself as a result of deranged nitrogen and energy homeostasis, with resultant neuronal, astrocyte and microglial dysfunction. Inflammation may also originate in the peripheral circulation and exert effects on the brain indirectly, via the release of pro-inflammatory mediators which directly signal to the brain via the vagus nerve. This review summarises the data that demonstrate the synergistic relationship of inflammation and ammonia that culminates in the manifestation of HE. Sterile inflammation arising from the inflamed or necrotic liver, circulating endotoxin arising from the gut (bacterial translocation) inducing immune dysfunction, and superimposed sepsis will be comprehensively discussed. Finally, this review will provide an overview of the existing and novel treatments on the horizon which can target the inflammatory response, and how they might translate into clinical practise as therapies in the prophylaxis and treatment of HE.
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Affiliation(s)
- Iona Coltart
- 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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Tranah TH, Vijay GKM, Ryan JM, Shawcross DL. Systemic inflammation and ammonia in hepatic encephalopathy. Metab Brain Dis 2013; 28:1-5. [PMID: 23224356 DOI: 10.1007/s11011-012-9370-2] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/01/2012] [Accepted: 11/26/2012] [Indexed: 02/07/2023]
Abstract
Infection and inflammation have been associated with the development of delirium for many centuries and there is a rapidly growing evidence base supporting the role of inflammation in exacerbating the neurological manifestations of both acute and chronic liver failure. Inflammation in the context of hepatic encephalopathy (HE) can arise directly within the brain itself resulting in astrocytic, microglial and neuronal dysfunction, impacting on the development of 'brain failure'. Inflammation may also develop systemically and indirectly influence brain function. Systemic inflammation develops following liver injury, resulting in hyperammonemia and a 'cytotoxic soup' of pro-inflammatory mediators which are released into the circulation and modulate the impact of ammonia on the brain. The aim of this review is to summarise the current evidence base supporting the synergistic role of systemic inflammation and hyperammonemia in the pathogenesis of hepatic encephalopathy. Systemic inflammation and ammonia induce neutrophil degranulation and release reactive oxygen species into the peripheral circulation that may ultimately cross the blood brain barrier. Circulating endotoxin arising from the gut (bacterial translocation), superimposed sepsis, and hyperammonemia upregulate the expression of microbial pattern recognition receptors such as Toll-like receptors. The early recognition and management of systemic inflammation may not only facilitate improved outcomes in HE but supports the development of novel therapeutic strategies that reduce circulating endotoxemia and immune cell dysfunction.
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Affiliation(s)
- Thomas H Tranah
- Institute of Liver Studies, King's College London School of Medicine at King's College Hospital, King's College Hospital, Denmark Hill, London, UK
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21
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Jain L, Sharma BC, Sharma P, Srivastava S, Agrawal A, Sarin SK. Serum endotoxin and inflammatory mediators in patients with cirrhosis and hepatic encephalopathy. Dig Liver Dis 2012; 44:1027-31. [PMID: 22883217 DOI: 10.1016/j.dld.2012.07.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2012] [Revised: 06/24/2012] [Accepted: 07/05/2012] [Indexed: 12/11/2022]
Abstract
BACKGROUND Recent observations suggest that inflammatory response may be important in the pathogenesis of hepatic encephalopathy. The aim of the study was to measure arterial ammonia, tumour necrosis factor-alpha, Interleukin-6, Interleukin-18, and serum endotoxin levels and their correlation with different grades of hepatic encephalopathy. METHODS 120 patients with cirrhosis were enrolled: 20 patients each of cirrhosis with grades I, II, III and IV hepatic encephalopathy, cirrhosis with and without minimal hepatic encephalopathy and healthy controls were tested for arterial ammonia, tumour necrosis factor-alpha, Interleukin-6, Interleukin-18 and serum endotoxin levels. RESULTS Median arterial ammonia, tumour necrosis factor-alpha, Interleukin-6, Interleukin-18 and serum endotoxin levels were significantly higher in patient with hepatic encephalopathy and minimal hepatic encephalopathy as compared to patients without minimal hepatic encephalopathy and healthy controls. Arterial ammonia (r = 0.72, p = 0.03), tumour necrosis factor alpha (r = 0.87, p = 0.02), Interleukin-6 (r = 0.50, p = 0.05), Interleukin-18 (r = 0.76, p = 0.02) and serum endotoxin (r = 0.91, p = 0.01) correlated with higher grades of hepatic encephalopathy. CONCLUSION In hepatic encephalopathy arterial ammonia, inflammatory mediators, and serum endotoxin are elevated and correlate with encephalopathy grade.
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Affiliation(s)
- Lokesh Jain
- Department of Gastroenterology, GB Pant Hospital, New Delhi, India
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22
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Sharma P, Sharma BC, Agrawal A, Sarin SK. Primary prophylaxis of overt hepatic encephalopathy in patients with cirrhosis: an open labeled randomized controlled trial of lactulose versus no lactulose. J Gastroenterol Hepatol 2012; 27:1329-35. [PMID: 22606978 DOI: 10.1111/j.1440-1746.2012.07186.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
BACKGROUND AND AIM Development of overt hepatic encephalopathy (HE) is associated with poor prognosis in patients with cirrhosis. Lactulose is used for the treatment of HE. There is no study on the prevention of overt HE using lactulose in patients who never had HE earlier. METHODS Consecutive cirrhotic patients who never had an episode of overt HE were randomized to receive lactulose (Gp-L) or no lactulose (Gp-NL). All patients were assessed by psychometry (number connection test [NCT-A and B], figure connection test if illiterate [FCT-A and B], digit symbol test [DST], serial dot test [SDT], line tracing test [LTT]) and critical flicker frequency test (CFF) at inclusion and after 3 months. These patients were followed every month for 12 months for development of overt HE. RESULTS Of 250 patients screened, 120 (48%) meeting the inclusion criteria were randomized to Gp-L (n = 60) and Gp-NL (n = 60). Twenty (19%) of 105 patients followed for 12 months developed an episode of overt HE. Six (11%) of 55 in the lactulose (Gp-L) group and 14 (28%) of 50 in the Gp-NL (P = 0.02) developed overt HE. Ten (20%) of 50 patients in Gp-NL and five (9%) of 55 patients in the Gp-L group died, P = 0.16. Number of patients with minimal hepatic encephalopathy (MHE) were comparable in two groups at baseline (Gp-L vs Gp-NL, 32:36, P = 0.29). Lactulose improved MHE in 66% of patients in Gp-L. Taking a cutoff < 38 Hz sensitivity and specificity of CFF in predicting HE were 52% and 77% at baseline and 52% and 82% at 3 months of treatment. On multivariate analysis, Child's score and presence of MHE at baseline were significantly associated with development of overt HE. CONCLUSIONS Lactulose is effective for primary prevention of overt hepatic encephalopathy in patients with cirrhosis.
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Affiliation(s)
- Praveen Sharma
- Department of Gastroenterology, G B Pant Hospital, New Delhi, India
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Martínez-Cengotitabengoa M, Mac-Dowell KS, Leza JC, Micó JA, Fernandez M, Echevarría E, Sanjuan J, Elorza J, González-Pinto A. Cognitive impairment is related to oxidative stress and chemokine levels in first psychotic episodes. Schizophr Res 2012; 137:66-72. [PMID: 22445462 DOI: 10.1016/j.schres.2012.03.004] [Citation(s) in RCA: 84] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 02/14/2012] [Accepted: 03/01/2012] [Indexed: 12/15/2022]
Abstract
INTRODUCTION This study measures the levels of various markers of oxidative stress and inflammation in blood samples from first-episode psychosis (FEP) patients, and examines the association between these peripheral biomarkers and cognitive performance at 6 months after treatment. METHODS Twenty-eight FEP patients and 28 healthy controls (matched by age, sex and educational level) had blood samples taken at admission for assessment of total antioxidant status, superoxide dismutase (SOD), total glutathione (GSH), catalase (CAT), glutathione peroxidase, lipid peroxidation, nitrites and the chemokine monocyte chemoattractant protein-1 (MCP-1). A battery of cognitive tests was also applied to the healthy controls and those FEP patients who were in remission at 6 months after the acute episode. RESULTS FEP patients had significantly lower levels of total antioxidant status, catalase and glutathione peroxidase, compared with the healthy controls. Regression analyses found that MCP-1 levels were negatively associated with learning and memory (verbal and working), nitrite levels were negatively associated with executive function, and glutathione levels were positively associated with executive function. CONCLUSION Our results suggest an association between certain peripheral markers of oxidative stress and inflammation and specific aspects of cognitive functioning in FEP patients. Further studies on the association between MCP-1 and cognition are warranted.
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Felipo V, Urios A, Montesinos E, Molina I, Garcia-Torres ML, Civera M, Olmo JAD, Ortega J, Martinez-Valls J, Serra MA, Cassinello N, Wassel A, Jordá E, Montoliu C. Contribution of hyperammonemia and inflammatory factors to cognitive impairment in minimal hepatic encephalopathy. Metab Brain Dis 2012; 27:51-8. [PMID: 22072427 DOI: 10.1007/s11011-011-9269-3] [Citation(s) in RCA: 125] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2011] [Accepted: 10/25/2011] [Indexed: 12/15/2022]
Abstract
To assess the contribution of hyperammonemia and inflammation to induction of mild cognitive impairment (or MHE). We analyzed the presence of mild cognitive impairment (CI) by using the PHES battery of psychometric tests and measured the levels of ammonia and of the inflammatory cytokines IL-6 and IL-18 in blood of patients with different types of liver or dermatological diseases resulting in different grades of hyperammonemia and/or inflammation. The study included patients with 1) liver cirrhosis, showing hyperammonemia and inflammation; 2) non-alcoholic fatty liver disease (NAFLD) showing inflammation but not hyperammonemia; 3) non-alcoholic steatohepatitis (NASH) showing inflammation and very mild hyperammonemia; 4) psoriasis, showing inflammation but not hyperammonemia; 5) keloids, showing both inflammation and hyperammonemia and 6) controls without inflammation or hyperammonemia. The data reported show that in patients with liver diseases, cognitive impairment may appear before progression to cirrhosis if hyperammonemia and inflammation are high enough. Five out of 11 patients with NASH, without liver cirrhosis, showed cognitive impairment associated with hyperammonemia and inflammation. Patients with keloids showed cognitive impairment associated with hyperammonemia and inflammation, in the absence of liver disease. Hyperammonemia or inflammation alone did not induce CI but the combination of certain levels of hyperammonemia and inflammation is enough to induce CI, even without liver disease.
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Affiliation(s)
- Vicente Felipo
- Laboratory of Neurobiology. Centro de Investigación Príncipe Felipe, Valencia, Spain
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Wright G, Vairappan B, Stadlbauer V, Mookerjee RP, Davies NA, Jalan R. Reduction in hyperammonaemia by ornithine phenylacetate prevents lipopolysaccharide-induced brain edema and coma in cirrhotic rats. Liver Int 2012; 32:410-9. [PMID: 22151131 DOI: 10.1111/j.1478-3231.2011.02698.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Accepted: 11/08/2011] [Indexed: 12/16/2022]
Abstract
OBJECTIVE In liver failure, inflammation synergistically exacerbates the deleterious cerebral effects of ammonia. The aims were to test whether treatment with the ammonia-lowering agent ornithine phenylacetate (OP) and/or anti-TNF-α (infliximab) prevent the deleterious brain consequences of lipopolysaccharide (LPS) in cirrhotic rats. DESIGN Rats 4 weeks following bile duct-ligation (BDL), sham-operation (sham) and/or 7 days hyperammonemic feed (HD), were randomized to receive LPS (1 mg/kg) or saline, and treatment with either 3 days intraperitoneal injections of OP (0.6 g/kg) and/or infliximab, 10 mg/kg. Animals were sacrificed at coma stages or at 3 h. RESULTS In sham rats, both HD and LPS increased brain water, with an increase in ammonia in the former and brain cytokines in the latter but with no effect on consciousness. BDL + HD rats caused significantly higher plasma ammonia, TNF-α and IL-6 levels compared to sham. LPS significantly worsened coma stage, increased brain water and plasma and brain TNF-α. OP significantly delayed LPS-induced progression to coma stages (P < 0.009), reduced arterial ammonia and brain water (P < 0.001 and P < 0.01 respectively), which was associated with a significant reduction in cytokines. Infliximab significantly reduced plasma and brain cytokines, but not brain water. OP + infliximab attenuated increase in brain water and delayed occurrence of coma, which was not different to OP alone. In BDL rats, OP reduced the expression of brain iNOS and NFκB. CONCLUSION Reduction in ammonia with OP in cirrhotic rats prevents LPS-induced brain edema and delays coma, suggesting that ammonia may prime the brain to the deleterious effect of LPS, possibly through effects on iNOS and NFκB related mechanisms.
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Affiliation(s)
- Gavin Wright
- Liver Failure Group, UCL Institute of Hepatology, Royal Free Hospital, London, UK
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26
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Contribution of hyperammonemia and inflammatory factors to cognitive impairment in minimal hepatic encephalopathy. Metab Brain Dis 2011. [PMID: 22072427 DOI: 10.1007/s11011-011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
To assess the contribution of hyperammonemia and inflammation to induction of mild cognitive impairment (or MHE). We analyzed the presence of mild cognitive impairment (CI) by using the PHES battery of psychometric tests and measured the levels of ammonia and of the inflammatory cytokines IL-6 and IL-18 in blood of patients with different types of liver or dermatological diseases resulting in different grades of hyperammonemia and/or inflammation. The study included patients with 1) liver cirrhosis, showing hyperammonemia and inflammation; 2) non-alcoholic fatty liver disease (NAFLD) showing inflammation but not hyperammonemia; 3) non-alcoholic steatohepatitis (NASH) showing inflammation and very mild hyperammonemia; 4) psoriasis, showing inflammation but not hyperammonemia; 5) keloids, showing both inflammation and hyperammonemia and 6) controls without inflammation or hyperammonemia. The data reported show that in patients with liver diseases, cognitive impairment may appear before progression to cirrhosis if hyperammonemia and inflammation are high enough. Five out of 11 patients with NASH, without liver cirrhosis, showed cognitive impairment associated with hyperammonemia and inflammation. Patients with keloids showed cognitive impairment associated with hyperammonemia and inflammation, in the absence of liver disease. Hyperammonemia or inflammation alone did not induce CI but the combination of certain levels of hyperammonemia and inflammation is enough to induce CI, even without liver disease.
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Srivastava A, Yadav SK, Yachha SK, Thomas MA, Saraswat VA, Gupta RK. Pro-inflammatory cytokines are raised in extrahepatic portal venous obstruction, with minimal hepatic encephalopathy. J Gastroenterol Hepatol 2011; 26:979-86. [PMID: 21362045 DOI: 10.1111/j.1440-1746.2011.06706.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
BACKGROUND AND AIMS Minimal hepatic encephalopathy (MHE) and hyperammonemia are seen in patients with extrahepatic portal venous obstruction (EHPVO). Inflammation has been shown to play an important role in the pathogenesis of hepatic encephalopathy in cirrhotics. This study assessed serum pro-inflammatory cytokines and their correlation with hyperammonemia, (1)H-magnetic resonance (MR) spectroscopy-derived brain glutamine, and diffusion tensor imaging (DTI)-derived metrics in patients with EPHVO, with and without MHE. METHODS Neuropsychological tests, DTI, (1)H-MR spectroscopy, and estimation of blood ammonia and pro-inflammatory cytokines (tumor necrosis factor-α[TNF-α] and interleukin-6 [IL-6]) were done in 20 patients with EHPVO and eight healthy controls. RESULTS Pro-inflammatory cytokines (TNF-α and IL-6), blood ammonia, brain glutamine, and mean diffusivity were increased in both patient groups, as compared to controls. Patients with MHE (n-12) had significantly higher TNF-α, IL-6, blood ammonia, brain glutamine, and mean diffusivity, signifying brain edema, than controls. A significant, positive correlation was seen between TNF-α and IL-6 and between blood ammonia and TNF-α, IL-6, and brain glutamine. Significant, positive correlations of TNF-α, IL-6, and blood ammonia with mean diffusivity values were seen in various brain regions, including spectroscopy voxel-derived mean diffusivity. CONCLUSION Patients with extrahepatic portal vein obstruction have inflammation and hyperammonemia made evident by higher blood TNF-α, IL-6, ammonia, and brain glutamine levels. A significant correlation between hyperammonemia, pro-inflammatory cytokines, and cerebral edema on DTI in various brain regions suggests that both these factors play a role in the pathogenesis of MHE in these patients.
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Affiliation(s)
- Anshu Srivastava
- Department of Pediatric Gastroenterology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, India
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Abstract
Hepatic encephalopathy is a complex and potentially reversible neuropsychiatric syndrome complicating acute or chronic liver disease. Clinical manifestations are multiple and varied, ranging from minimal neurological changes to coma. Ammonia is the main toxic substance involved in the pathogenesis of hepatic encephalopathy, although other mechanisms, such as modifications of the blood-brain barrier, disruptions in neurotransmission and abnormalities in GABAergic and benzodiazepine pathways may also play a role. The identification and treatment of precipitating factors is crucial in the management of patients with hepatic encephalopathy. Current treatments are based on reducing intestinal ammonia load by agents such as antibiotics or disaccharides, although their efficacy is yet to be clearly established.
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Rodrigo R, Cauli O, Gomez-Pinedo U, Agusti A, Hernandez-Rabaza V, Garcia-Verdugo JM, Felipo V. Hyperammonemia induces neuroinflammation that contributes to cognitive impairment in rats with hepatic encephalopathy. Gastroenterology 2010; 139:675-84. [PMID: 20303348 DOI: 10.1053/j.gastro.2010.03.040] [Citation(s) in RCA: 235] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2009] [Revised: 02/08/2010] [Accepted: 03/08/2010] [Indexed: 12/12/2022]
Abstract
BACKGROUND & AIMS Hyperammonemia and inflammation cooperate to induce neurological alterations in hepatic encephalopathy. Recent studies in animal models suggest that chronic hyperammonemia and neuroinflammation impair learning ability by the same mechanism. Chronic hyperammonemia might induce inflammatory factors in the brain that impair cognitive function. We sought to determine whether hyperammonemia itself induces neuroinflammation, whether ammonia-induced neuroinflammation mediates cognitive impairment, and whether neuroinflammation also occurs in rats with bile duct ligation (BDL rats)-a model of chronic liver injury that results in hyperammonemia and hepatic encephalopathy. METHODS Chronic moderate hyperammonemia was induced by feeding male Wistar rats an ammonium-containing diet or performing BDL. Rats that received a standard diet or a sham operation were used as controls. Neuroinflammation was assessed by measuring activation of microglia and inflammatory factors. Brain samples were collected from hyperammonemic and BDL rats; microglial activation was determined by immunohistochemistry and quantification of inflammatory markers (ie, inducible nitric oxide synthase, interleukin-1beta, and prostaglandin E2). Learning ability and motor activity were assessed in hyperammonemic and BDL rats given ibuprofen as an anti-inflammatory agent. RESULTS Chronic moderate hyperammonemia or BDL activated the microglia, especially in cerebellum; increased inducible nitric oxide synthase, interleukin-1beta, and prostaglandin E2 levels; and impaired cognitive and motor function, compared with controls. Ibuprofen reduced microglial activation and restored cognitive and motor functions in the hyperammonemic and BDL rats. CONCLUSIONS Chronic hyperammonemia is sufficient to induce microglial activation and neuroinflammation; these contribute to the cognitive and motor alterations that occur during hepatic encephalopathy.
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Affiliation(s)
- Regina Rodrigo
- Laboratory of Neurobiology, Centro de Investigación Príncipe Felipe, Valencia, Spain
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Seyan AS, Hughes RD, Shawcross DL. Changing face of hepatic encephalopathy: Role of inflammation and oxidative stress. World J Gastroenterol 2010; 16:3347-57. [PMID: 20632436 PMCID: PMC2904880 DOI: 10.3748/wjg.v16.i27.3347] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The face of hepatic encephalopathy (HE) is changing. This review explores how this neurocognitive disorder, which is associated with both acute and chronic liver injury, has grown to become a dynamic syndrome that spans a spectrum of neuropsychological impairment, from normal performance to coma. The central role of ammonia in the pathogenesis of HE remains incontrovertible. However, over the past 10 years, the HE community has begun to characterise the key roles of inflammation, infection, and oxidative/nitrosative stress in modulating the pathophysiological effects of ammonia on the astrocyte. This review explores the current thoughts and evidence base in this area and discusses the potential role of existing and novel therapies that might abrogate the oxidative and nitrosative stresses inflicted on the brain in patients with, or at risk of developing, HE.
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IL-6 and IL-18 in blood may discriminate cirrhotic patients with and without minimal hepatic encephalopathy. J Clin Gastroenterol 2009; 43:272-9. [PMID: 18562979 DOI: 10.1097/mcg.0b013e31815e7f58] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
BACKGROUND AND AIMS Patients with liver cirrhosis may present minimal hepatic encephalopathy (MHE) that can be unveiled using specific neuropsychologic examination. Evaluation of MHE in cirrhotic patients might have prognostic value. The psychometric HE score (PHES) has been recommended as the "gold standard" in the diagnosis of MHE. It has been proposed that critical flicker frequency (CFF) analysis would be useful for easier detection of MHE. It would also be useful to have some peripheral parameter that could reflect the presence of MHE. It has been recently proposed that inflammation-associated alterations and hyperammonemia may cooperate in the induction of hepatic encephalopathy. The aim of the present work was to assess whether there is a correlation between the alterations in parameters reflecting inflammation, hyperammonemia, and the presence of MHE. METHODS We have studied in 55 patients with liver cirrhosis and 26 controls the performance in the PHES battery and the CFF, ammonia, and some interleukins (ILs) as inflammatory markers. RESULTS IL-6 and IL-18 were significantly higher (2.5-fold and 2.2-fold, respectively) in patients with MHE than in those without MHE. There were significant correlations between IL-6 or IL-18 levels and PHES score and CFF. Moreover, all patients with MHE had IL-6 levels higher than 11 ng/mL, whereas all patients without MHE had IL-6 levels lower than 11 ng/mL. CONCLUSIONS Inflammatory alterations related with IL-6 and IL-18 may contribute to MHE. Serum concentration of IL-6 and IL-18 may be useful to discriminate cirrhotic patients with and without MHE.
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Monfort P, Cauli O, Montoliu C, Rodrigo R, Llansola M, Piedrafita B, El Mlili N, Boix J, Agustí A, Felipo V. Mechanisms of cognitive alterations in hyperammonemia and hepatic encephalopathy: therapeutical implications. Neurochem Int 2009; 55:106-12. [PMID: 19428813 DOI: 10.1016/j.neuint.2009.01.021] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2008] [Revised: 01/14/2009] [Accepted: 01/19/2009] [Indexed: 01/06/2023]
Abstract
Patients with liver diseases (e.g. cirrhosis) may present hepatic encephalopathy (HE), an alteration in cerebral function which is a consequence of previous failure of liver function. Patients with minimal or clinical HE present different levels of cognitive impairment. Hyperammonemia is considered a main contributor to the neurological alterations in HE. Animal models of chronic HE (e.g. rats with portacaval shunts) or of "pure" hyperammonemia also show impaired cognitive function. The studies summarized here show that the impairment of some types of cognitive function in chronic HE is due to the impaired function of the glutamate-nitric oxide-cGMP pathway in brain. Both hyperammonemia and neuroinflammation contribute to the impairment of the pathway and of cognitive function. Treatment of rats with chronic HE or hyperammonemia with inhibitors of phosphodiesterase 5 restores the function of the glutamate-nitric oxide-cGMP pathway and cGMP levels in brain as well as the ability to learn a Y maze conditional discrimination task. The same beneficial effects may be obtained by treating the rats chronically with an anti-inflammatory, ibuprofen. As the function of this pathway is also altered in brain of patients died in HE, this alteration would also contribute to cognitive impairment in patients with HE. Increasing cGMP by using inhibitors of phosphodiesterase 5 (PDE-5) or anti-inflammatories (under safe conditions) would be therefore a new therapeutic approach to improve learning and memory performance in individuals with minimal or clinical HE.
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Affiliation(s)
- Pilar Monfort
- Laboratory of Neurobiology, Centro de Investigacion Principe Felipe, Valencia, Spain
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Luiking YC, Hallemeesch MM, van de Poll MC, Dejong CHC, de Jonge WJ, Lamers WH, Deutz NEP. Reduced citrulline availability by OTC deficiency in mice is related to reduced nitric oxide production. Am J Physiol Endocrinol Metab 2008; 295:E1315-22. [PMID: 18697914 DOI: 10.1152/ajpendo.00055.2008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The amino acid arginine is the sole precursor for nitric oxide (NO) synthesis. We recently demonstrated that an acute reduction of circulating arginine does not compromise basal or LPS-inducible NO production in mice. In the present study, we investigated the importance of citrulline availability in ornithine transcarbamoylase-deficient spf(ash) (OTCD) mice on NO production, using stable isotope techniques and C57BL6/J (wild-type) mice controls. Plasma amino acids and tracer-to-tracee ratios were measured by LC-MS. NO production was measured as the in vivo conversion of l-[guanidino-(15)N(2)]arginine to l-[guanidine-(15)N]citrulline; de novo arginine production was measured as conversion of l-[ureido-(13)C-5,5-(2)H(2)]citrulline to l-[guanidino-(13)C-5,5-(2)H(2)]arginine. Protein metabolism was measured using l-[ring-(2)H(5)]phenylalanine and l-[ring-(2)H(2)]tyrosine. OTC deficiency caused a reduction of systemic citrulline concentration and production to 30-50% (P < 0.001), reduced de novo arginine production (P < 0.05), reduced whole-body NO production to 50% (P < 0.005), and increased net protein breakdown by a factor of 2-4 (P < 0.001). NO production was twofold higher in female than in male OTCD mice in agreement with the X-linked location of the OTC gene. In response to LPS treatment (10 mg/kg ip), circulating arginine increased in all groups (P < 0.001), and NO production was no longer affected by the OTC deficiency due to increased net protein breakdown as a source for arginine. Our study shows that reduced citrulline availability is related to reduced basal NO production via reduced de novo arginine production. Under basal conditions this is probably cNOS-mediated NO production. When sufficient arginine is available after LPS stimulated net protein breakdown, NO production is unaffected by OTC deficiency.
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Affiliation(s)
- Yvette C Luiking
- Univ. of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
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Cauli O, Rodrigo R, Piedrafita B, Boix J, Felipo V. Inflammation and hepatic encephalopathy: ibuprofen restores learning ability in rats with portacaval shunts. Hepatology 2007; 46:514-9. [PMID: 17659565 DOI: 10.1002/hep.21734] [Citation(s) in RCA: 169] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
UNLABELLED One of the neurological alterations in patients with minimal or overt hepatic encephalopathy is cognitive impairment. This impairment is reproduced in rats with chronic liver failure due to portacaval shunt (PCS). These rats show decreased ability to learn a conditional discrimination task in a Y-maze, likely due to reduced function of the glutamate-nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) pathway in brain. It has been proposed that inflammation exacerbates the neuropsychological alterations induced by hyperammonemia, suggesting that inflammation-associated alterations may contribute to cognitive impairment in hepatic encephalopathy. This study assessed whether treatment with an anti-inflammatory drug, ibuprofen, is able to restore the function of the glutamate-NO-cGMP pathway in cerebral cortex in brain in vivo and/or learning ability in PCS rats. We show that PCS rats have increased levels of interleukin-6 and increased activities of cyclooxygenase and of inducible NO synthase in cerebral cortex, indicating the presence of inflammation. Chronic treatment with ibuprofen normalizes cyclooxygenase and inducible NO synthase activities but not interleukin-6 levels. Moreover, ibuprofen normalizes the function of the glutamate-NO-cGMP pathway in cerebral cortex in vivo and completely restores the ability of rats with chronic liver failure to learn the Y-maze task. This supports that inflammation contributes to the cognitive impairment in hepatic encephalopathy. CONCLUSION the results reported point to the possible therapeutic utility of decreasing inflammation in the treatment of the cognitive deficits in patients with minimal or overt hepatic encephalopathy.
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Affiliation(s)
- Omar Cauli
- Laboratory of Neurobiology, Centro de Investigación Príncipe Felipe, Valencia, Spain
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