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Sasaki T, Kakisaka K, Kuroda H, Matsumoto T. Nutritional management for acute liver failure. Hepatol Res 2024. [PMID: 38949571 DOI: 10.1111/hepr.14090] [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: 04/19/2024] [Revised: 06/04/2024] [Accepted: 06/14/2024] [Indexed: 07/02/2024]
Abstract
Acute liver failure (ALF) induces increased energy expenditure and disrupts the metabolism of essential nutrients. Hepatic encephalopathy is a complication of ALF with a poor prognosis and mainly involves the metabolic disturbance of amino acids in its pathogenesis. In this review, we discuss the nutritional management for ALF in consideration of the pathophysiology of ALF with respect to the impairment of hepatocyte function. It is known that enteral nutrition is recommended for patients with ALF, while parenteral nutrition is recommended for patients who cannot tolerate enteral nutrition. As ALF leads to a hypermetabolic state, the energy intake is recommended to cover 1.3 times the resting energy expenditure. Because of the high risk of hypoglycemia associated with disturbances in glucose metabolism, substantial glucose intake is recommended. Along with the deterioration of glucose metabolism, protein metabolism is also disrupted. As patients with ALF have increased systemic protein catabolism together with decreased protein synthesis, appropriate amounts of amino acids or protein under monitoring serum ammonia levels are recommended. In conclusion, nutritional management based on the understanding of nutritional pathophysiology is a pivotal therapeutic approach for patients with ALF. The approach should be individualized in the acute phase, the recovery phase, and the pretransplant phase.
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Affiliation(s)
- Tokio Sasaki
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Iwate Medical University, School of Medicine, Yahaba, Japan
| | - Keisuke Kakisaka
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Iwate Medical University, School of Medicine, Yahaba, Japan
| | - Hidekatsu Kuroda
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Iwate Medical University, School of Medicine, Yahaba, Japan
| | - Takayuki Matsumoto
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Iwate Medical University, School of Medicine, Yahaba, Japan
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Ouyang S, Zhu J, Cao Q, Liu J, Zhang Z, Zhang Y, Wu J, Sun S, Fu J, Chen Y, Tong J, Liu Y, Zhang J, Shen F, Li D, Wang P. Gasdermin-E-Dependent Non-Canonical Pyroptosis Promotes Drug-Induced Liver Failure by Promoting CPS1 deISGylation and Degradation. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2305715. [PMID: 38417117 PMCID: PMC11040357 DOI: 10.1002/advs.202305715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 12/22/2023] [Indexed: 03/01/2024]
Abstract
Drug-induced liver injury (DILI) is a significant global health issue that poses high mortality and morbidity risks. One commonly observed cause of DILI is acetaminophen (APAP) overdose. GSDME is an effector protein that induces non-canonical pyroptosis. In this study, the activation of GSDME, but not GSDMD, in the liver tissue of mice and patients with APAP-DILI is reported. Knockout of GSDME, rather than GSDMD, in mice protected them from APAP-DILI. Mice with hepatocyte-specific rescue of GSDME reproduced APAP-induced liver injury. Furthermore, alterations in the immune cell pools observed in APAP-induced DILI, such as the replacement of TIM4+ resident Kupffer cells (KCs) by monocyte-derived KCs, Ly6C+ monocyte infiltration, MerTk+ macrophages depletion, and neutrophil increase, reappeared in mice with hepatocyte-specific rescue of GSDME. Mechanistically, APAP exposure led to a substantial loss of interferon-stimulated gene 15 (ISG15), resulting in deISGylation of carbamoyl phosphate synthetase-1 (CPS1), promoted its degradation via K48-linked ubiquitination, causing ammonia clearance dysfunction. GSDME deletion prevented these effects. Delayed administration of dimethyl-fumarate inhibited GSDME cleavage and alleviated ammonia accumulation, mitigating liver injury. This findings demonstrated a previously uncharacterized role of GSDME in APAP-DILI by promoting pyroptosis and CPS1 deISGylation, suggesting that inhibiting GSDME can be a promising therapeutic option for APAP-DILI.
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Affiliation(s)
- Shen‐Xi Ouyang
- Department of PharmacyShanghai Tenth People's HospitalSchool of MedicineTongji UniversityShanghai200092China
| | - Jia‐Hui Zhu
- Department of PharmacyShanghai Tenth People's HospitalSchool of MedicineTongji UniversityShanghai200092China
| | - Qi Cao
- The Center for Basic Research and Innovation of Medicine and Pharmacy (MOE), Department of PharmacologySchool of PharmacyNaval Medical University/Second Military Medical UniversityShanghai200433China
- Shanghai Key Laboratory for Pharmaceutical Metabolite ResearchNaval Medical University/Second Military Medical UniversityShanghai200433China
- National Demonstration Center for Experimental Pharmaceutical EducationNaval Medical University/Second Military Medical UniversityShanghai200433China
| | - Jian Liu
- Department of Hepatic SurgeryThe Eastern Hepatobiliary Surgery HospitalNaval Medical University/Second Military Medical UniversityShanghai200438China
| | - Zhen Zhang
- Department of PharmacyShanghai Tenth People's HospitalSchool of MedicineTongji UniversityShanghai200092China
| | - Yan Zhang
- Department of PharmacyShanghai Tenth People's HospitalSchool of MedicineTongji UniversityShanghai200092China
| | - Jing‐Wen Wu
- Department of PharmacyShanghai Tenth People's HospitalSchool of MedicineTongji UniversityShanghai200092China
| | - Si‐Jia Sun
- Department of PharmacyShanghai Tenth People's HospitalSchool of MedicineTongji UniversityShanghai200092China
| | - Jiang‐Tao Fu
- The Center for Basic Research and Innovation of Medicine and Pharmacy (MOE), Department of PharmacologySchool of PharmacyNaval Medical University/Second Military Medical UniversityShanghai200433China
- Shanghai Key Laboratory for Pharmaceutical Metabolite ResearchNaval Medical University/Second Military Medical UniversityShanghai200433China
- National Demonstration Center for Experimental Pharmaceutical EducationNaval Medical University/Second Military Medical UniversityShanghai200433China
| | - Yi‐Ting Chen
- The Center for Basic Research and Innovation of Medicine and Pharmacy (MOE), Department of PharmacologySchool of PharmacyNaval Medical University/Second Military Medical UniversityShanghai200433China
- Shanghai Key Laboratory for Pharmaceutical Metabolite ResearchNaval Medical University/Second Military Medical UniversityShanghai200433China
- National Demonstration Center for Experimental Pharmaceutical EducationNaval Medical University/Second Military Medical UniversityShanghai200433China
| | - Jie Tong
- Department of PharmacyShanghai Tenth People's HospitalSchool of MedicineTongji UniversityShanghai200092China
| | - Yi Liu
- Department of PharmacyShanghai Tenth People's HospitalSchool of MedicineTongji UniversityShanghai200092China
| | - Jia‐Bao Zhang
- The Center for Basic Research and Innovation of Medicine and Pharmacy (MOE), Department of PharmacologySchool of PharmacyNaval Medical University/Second Military Medical UniversityShanghai200433China
- Shanghai Key Laboratory for Pharmaceutical Metabolite ResearchNaval Medical University/Second Military Medical UniversityShanghai200433China
- National Demonstration Center for Experimental Pharmaceutical EducationNaval Medical University/Second Military Medical UniversityShanghai200433China
| | - Fu‐Ming Shen
- Department of PharmacyShanghai Tenth People's HospitalSchool of MedicineTongji UniversityShanghai200092China
| | - Dong‐Jie Li
- Department of PharmacyShanghai Tenth People's HospitalSchool of MedicineTongji UniversityShanghai200092China
| | - Pei Wang
- The Center for Basic Research and Innovation of Medicine and Pharmacy (MOE), Department of PharmacologySchool of PharmacyNaval Medical University/Second Military Medical UniversityShanghai200433China
- Shanghai Key Laboratory for Pharmaceutical Metabolite ResearchNaval Medical University/Second Military Medical UniversityShanghai200433China
- National Demonstration Center for Experimental Pharmaceutical EducationNaval Medical University/Second Military Medical UniversityShanghai200433China
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Zhang H, Sun Y, Zou Y, Chen C, Wang S. Stigmasterol and gastrodin, two major components of banxia-baizhu-tianma decoction, alleviated the excessive phlegm-dampness hypertension by reducing lipid accumulation. JOURNAL OF ETHNOPHARMACOLOGY 2024; 319:117193. [PMID: 37726069 DOI: 10.1016/j.jep.2023.117193] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 09/10/2023] [Accepted: 09/14/2023] [Indexed: 09/21/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Banxia baizhu tianma decoction (BBTD) originated from the Qing Dynasty Chinese medicine book "Medical Xinwu", which has a clinical application history of more than 300 years. It's a classic prescription for expelling phlegm, extinguishing wind, strengthening the spleen (traditional Chinese medicine, ie, TCM, refers to the spleen channel) and dissipating excessive fluid based on TCM theory. BBTD is particularly effective in the treatment of excessive phlegm-dampness hypertension. However, the precise pharmacological effect of each herb of BBTD on hypertension treatment is not yet fully understood. AIM OF THE STUDY To investigate the pharmacological effects of each herb in BBTD on hypertension treatment and to explore the mechanisms behind them. MATERIALS AND METHODS A high-fat-diet fed animal model was developed to evaluate the efficacy of different groups of drugs in BBTD for the treatment of hypertension. Untargeted metabolism was used to detect the metabolic changes after modeling and drug intervention. Then, Stigmasterol (STI) and gastrodin (GAS), major components of Pinellia Ternate Makino and Gastrodia elata Blume, were selected for treatment on HepG2 cell steatosis model. Real-time quantitative polymerase chain reaction and Western blotting were used to detect changes of corresponding gene and protein after drug intervention to explore the exam anti-hyperlipidemia mechanism of STI and GAS combination. RESULTS The weight gain, elevated blood pressure and increased blood lipids induced by high-fat-diet were significantly decreased (p < 0.05) after each prescription medicine intervention in a dose-dependent manner. In addition, 28 differential metabolites (DMs) were detected after modeling and were regulated to normal at varying degrees after each drug group treatment. In addition, eight of the 28 DMs were significantly different from the model group after the full prescription drug intervention, primarily related to four metabolic pathways, while only two metabolites were significantly different from the model group after the unprincipled drug intervention, related to one metabolic pathway. In HepG2 hyperlipidemia cell model, STI, GAS and their combination significantly decreased TC, TG levels and lipid accumulation (p < 0.05), and decreased sterol regulatory element-binding protein 1c (SREBP-1c), fatty acid synthase (FAS), stearoyl-CoA desaturase-1 (SCD1) and their protein expressions (p < 0.05), increased adenosine monophosphate-activated protein kinase (AMPK) and it's protein expression (p < 0.05). The two drugs work better in combination than alone. CONCLUSION BBTD has been shown to be effective in reducing lipid accumulation in a high-fat rat model, as well as in restoring the model-induced abnormal metabolites to normal levels in a dose-dependent manner. Pinellia ternata Makino and Gastrodia elata Blume, the main components of BBTD, may regulate lipid metabolism through fatty acid biosynthesis, arginine and proline metabolism. Their main active agents, STI and GAS, effectively reduce lipid accumulation and lipid content in cells and regulate the expression levels of genes and proteins associated with lipid metabolism. These results suggest that BBTD may regulate lipid metabolism via AMPK/SREBP-1c pathway.
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Affiliation(s)
- Honghua Zhang
- School of Pharmacy, Hangzhou Normal University, Hangzhou, China; Key Laboratory of Elemene Class Anti-Cancer Chinese Medicines, Engineering Laboratory of Development and Application of Traditional Chinese Medicines, Collaborative Innovation Center of Traditional Chinese Medicines of Zhejiang Province, Hangzhou Normal University, Hangzhou, Zhejiang, 311121, China.
| | - Yunting Sun
- Hangzhou TCM Hospital Afflitiated to Zhejiang Chinese Medical University, Hangzhou, Zhejiang, 311121, China.
| | - Yuqing Zou
- School of Pharmacy, Hangzhou Normal University, Hangzhou, China; Key Laboratory of Elemene Class Anti-Cancer Chinese Medicines, Engineering Laboratory of Development and Application of Traditional Chinese Medicines, Collaborative Innovation Center of Traditional Chinese Medicines of Zhejiang Province, Hangzhou Normal University, Hangzhou, Zhejiang, 311121, China.
| | - Cheng Chen
- School of Pharmacy, Hangzhou Normal University, Hangzhou, China; Key Laboratory of Elemene Class Anti-Cancer Chinese Medicines, Engineering Laboratory of Development and Application of Traditional Chinese Medicines, Collaborative Innovation Center of Traditional Chinese Medicines of Zhejiang Province, Hangzhou Normal University, Hangzhou, Zhejiang, 311121, China.
| | - Shuling Wang
- School of Pharmacy, Hangzhou Normal University, Hangzhou, China; Key Laboratory of Elemene Class Anti-Cancer Chinese Medicines, Engineering Laboratory of Development and Application of Traditional Chinese Medicines, Collaborative Innovation Center of Traditional Chinese Medicines of Zhejiang Province, Hangzhou Normal University, Hangzhou, Zhejiang, 311121, China.
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Datsko V, Loi H, Datsko T, Mudra A, Mykolenko A, Golovata T, Furdela M, Orel Y, Smachylo I, Burak A, Klantsa M, Oleshchuk O. Nitric oxide-mediated effects of L-ornithine-L-aspartate in acute toxic liver injury. PHARMACIA 2022. [DOI: 10.3897/pharmacia.69.e83067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
This study was aimed to investigate nitric oxide-dependent mechanisms of L-ornithine-L-aspartate (LOLA) action in acute toxic liver injury in rats. Acute hepatitis was induced in Wistar rats using 50% oil solution of tetrachloromethane (CCl4) intragastrically (2 g/kg) twice in a 24 hour interval. Intraperitoneal treatment with LOLA (200 mg/kg) was started 6 hours after the second CCl4 administration and maintained for 3 consecutive days. L-Nω-Nitroarginine Methyl Ester (L-NAME) was used intraperitoneally (10 mg/kg). In CCl4-induced hepatitis, LOLA restores the structure of hepatocytes and prevents aminotransferases, alkaline phosphatase and gamma-glutamyl transferase elevation. It decreases total bilirubin concentration but does not affect increased cholesterol level. LOLA augments urea concentration, total protein level in blood and liver as well as serum and liver content of nitrite anions. LOLA enhances activity of catalase, glutathione S-transferase, manganese superoxide dismutase, increases reduced glutathione level and total antioxidant capacity and decreases thiobarbituric acid reactive substances level. The concomitant use of L-NAME inhibits the action of LOLA to enhance nitrite anions synthesis both in serum and liver, to delay the recovery of hepatocytes, to counteract LOLA effect against blood total protein reduction, to prevent the decline in aminotransferases, alkaline phosphatase,, gamma-glutamyl transferase and glutathione S-transferase activity and to reduce catalase activity and reduced glutathione level. Therefore, in CCl4-induced hepatitis, LOLA effectively prevents cytolysis and cholestasis, improves liver metabolism and protects against oxidative stress. Partially, these changes occur in nitric oxide-mediated mechanism since the use of L-NAME declines most of LOLA effects.
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Zielińska M, Albrecht J, Popek M. Dysregulation of Astrocytic Glutamine Transport in Acute Hyperammonemic Brain Edema. Front Neurosci 2022; 16:874750. [PMID: 35733937 PMCID: PMC9207324 DOI: 10.3389/fnins.2022.874750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 05/17/2022] [Indexed: 11/13/2022] Open
Abstract
Acute liver failure (ALF) impairs ammonia clearance from blood, which gives rise to acute hyperammonemia and increased ammonia accumulation in the brain. Since in brain glutamine synthesis is the only route of ammonia detoxification, hyperammonemia is as a rule associated with increased brain glutamine content (glutaminosis) which correlates with and contributes along with ammonia itself to hyperammonemic brain edema-associated with ALF. This review focuses on the effects of hyperammonemia on the two glutamine carriers located in the astrocytic membrane: Slc38a3 (SN1, SNAT3) and Slc7a6 (y + LAT2). We emphasize the contribution of the dysfunction of either of the two carriers to glutaminosis- related aspects of brain edema: retention of osmotically obligated water (Slc38a3) and induction of oxidative/nitrosative stress (Slc7a6). The changes in glutamine transport link glutaminosis- evoked mitochondrial dysfunction to oxidative-nitrosative stress as formulated in the “Trojan Horse” hypothesis.
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6
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Kroupina K, Bémeur C, Rose CF. Amino acids, ammonia, and hepatic encephalopathy. Anal Biochem 2022; 649:114696. [DOI: 10.1016/j.ab.2022.114696] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 03/30/2022] [Accepted: 04/21/2022] [Indexed: 11/30/2022]
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Safadi R, Rahimi RS, Thabut D, Bajaj JS, Ram Bhamidimarri K, Pyrsopoulos N, Potthoff A, Bukofzer S, Wang L, Jamil K, Devarakonda KR. Pharmacokinetics/pharmacodynamics of L-ornithine phenylacetate in overt hepatic encephalopathy and the effect of plasma ammonia concentration reduction on clinical outcomes. Clin Transl Sci 2022; 15:1449-1459. [PMID: 35238476 PMCID: PMC9199870 DOI: 10.1111/cts.13257] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 01/31/2022] [Accepted: 02/08/2022] [Indexed: 12/19/2022] Open
Abstract
Hepatic encephalopathy (HE) is a serious neurocognitive complication of liver dysfunction, often associated with elevated plasma ammonia. Ornithine phenylacetate (OP), a potent ammonia scavenger, is being evaluated for the treatment of acute/overt HE. The pharmacokinetics and pharmacodynamics of OP in patients with HE were characterized in this phase IIb study (NCT01966419). Adult patients hospitalized with an overt HE episode, cirrhosis, and plasma ammonia above the upper limit of normal (ULN) who failed to improve after 48 hours’ standard care were randomly assigned to continuous intravenous OP (10, 15, or 20 g/day, based on Child–Turcotte–Pugh score) or matching placebo for 5 days. Plasma levels of ornithine and phenylacetic acid (PAA) and plasma/urinary levels of phenylacetylglutamine (PAGN) (primary metabolite of PAA) were regularly assessed; plasma ammonia level was the primary pharmacodynamic variable. PAA demonstrated dose‐dependent pharmacokinetics; ornithine and PAGN levels increased with dose. PAGN urinary excretion represented ~50%–60% of administered PAA across all doses. Mean reduction in plasma ammonia with OP at 3 hours postinfusion was significantly greater versus placebo (p = 0.014); and time to achieve plasma ammonia less than or equal to the ULN was significantly reduced (p = 0.028). Achievement of clinical response based on HE stage was associated with a greater reduction in mean plasma ammonia level (p = 0.009). OP effects on plasma ammonia were consistent with its proposed mechanism of action as a primary ammonia scavenger, with a significant association between reduced plasma ammonia and improvement in HE stage. OP should be further evaluated as a promising treatment for hyperammonemia in patients with overt HE.
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Affiliation(s)
- Rifaat Safadi
- Director of The Liver Institute, Hadassah Medical Organization, Hadassah Hebrew University Medical Center, Jerusalem, Israel
| | - Robert S Rahimi
- Baylor Scott and White Hospital, Baylor University Medical Center, Dallas, Texas, USA
| | - Dominique Thabut
- Brain Liver Pitié-Salpêtrière (B-LIPS) Study Group, Paris Sorbonne Université, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Jasmohan S Bajaj
- Department of Medicine, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia, USA
| | | | - Nikolaos Pyrsopoulos
- Rutgers New Jersey Medical School and University Hospital, Newark, New Jersey, USA
| | - Amy Potthoff
- Ocera Therapeutics, Inc., Redwood City, California, USA
| | - Stan Bukofzer
- Ocera Therapeutics, Inc., Redwood City, California, USA
| | - Laurene Wang
- INDAPharma, LLC, Chapel Hill, North Carolina, USA
| | - Khurram Jamil
- Mallinckrodt Pharmaceuticals, Hampton, New Jersey, USA
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DeMorrow S, Cudalbu C, Davies N, Jayakumar AR, Rose CF. 2021 ISHEN guidelines on animal models of hepatic encephalopathy. Liver Int 2021; 41:1474-1488. [PMID: 33900013 PMCID: PMC9812338 DOI: 10.1111/liv.14911] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Revised: 03/05/2021] [Accepted: 04/01/2021] [Indexed: 02/07/2023]
Abstract
This working group of the International Society of Hepatic Encephalopathy and Nitrogen Metabolism (ISHEN) was commissioned to summarize and update current efforts in the development and characterization of animal models of hepatic encephalopathy (HE). As defined in humans, HE in animal models is based on the underlying degree and severity of liver pathology. Although hyperammonemia remains the key focus in the pathogenesis of HE, other factors associated with HE have been identified, together with recommended animal models, to help explore the pathogenesis and pathophysiological mechanisms of HE. While numerous methods to induce liver failure and disease exist, less have been characterized with neurological and neurobehavioural impairments. Moreover, there still remains a paucity of adequate animal models of Type C HE induced by alcohol, viruses and non-alcoholic fatty liver disease; the most common etiologies of chronic liver disease.
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Affiliation(s)
- S DeMorrow
- Division of Pharmacology and Toxicology, College of Pharmacy, The University of Texas at Austin, Texas, USA; Department of Internal Medicine, Dell Medical School, The University of Texas at Austin, Texas, USA; Research division, Central Texas Veterans Healthcare System, Temple Texas USA.,Correspondance: Sharon DeMorrow, PhD, ; tel: +1-512-495-5779
| | - C Cudalbu
- Center for Biomedical Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - N Davies
- Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, United Kingdom
| | - AR Jayakumar
- General Medical Research, Neuropathology Section, R&D Service and South Florida VA Foundation for Research and Education Inc; Obstetrics, Gynecology and Reproductive Sciences, University of Miami School of Medicine, Miami FL, USA
| | - CF Rose
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montreal, Canada
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9
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Clément MA, Bosoi CR, Oliveira MM, Tremblay M, Bémeur C, Rose CF. Bile-duct ligation renders the brain susceptible to hypotension-induced neuronal degeneration: Implications of ammonia. J Neurochem 2021; 157:561-573. [PMID: 33382098 DOI: 10.1111/jnc.15290] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Revised: 12/22/2020] [Accepted: 12/29/2020] [Indexed: 12/11/2022]
Abstract
Hepatic encephalopathy (HE) is a debilitating neurological complication of cirrhosis. By definition, HE is considered a reversible disorder, and therefore HE should resolve following liver transplantation (LT). However, persisting neurological complications are observed in as many as 47% of LT recipients. LT is an invasive surgical procedure accompanied by various perioperative factors such as blood loss and hypotension which could influence outcomes post-LT. We hypothesize that minimal HE (MHE) renders the brain frail and susceptible to hypotension-induced neuronal cell death. Six-week bile duct-ligated (BDL) rats with MHE and respective SHAM-controls were used. Several degrees of hypotension (mean arterial pressure of 30, 60 and 90 mm Hg) were induced via blood withdrawal from the femoral artery and maintained for 120 min. Brains were collected for neuronal cell count and apoptotic analysis. In a separate group, BDL rats were treated for MHE with the ammonia-lowering strategy ornithine phenylacetate (OP; MNK-6105), administered orally (1 g/kg) for 3 weeks before induction of hypotension. Hypotension 30 and 60 mm Hg (not 90 mm Hg) significantly decreased neuronal marker expression (NeuN) and cresyl violet staining in the frontal cortex compared to respective hypotensive SHAM-operated controls as well as non-hypotensive BDL rats. Neuronal degeneration was associated with an increase in cleaved caspase-3, suggesting the mechanism of cell death was apoptotic. OP treatment attenuated hyperammonaemia, improved anxiety and activity, and protected the brain against hypotension-induced neuronal cell death. Our findings demonstrate that rats with chronic liver disease and MHE are more susceptible to hypotension-induced neuronal cell degeneration. This highlights MHE at the time of LT is a risk factor for poor neurological outcome post-transplant and that treating for MHE pre-LT might reduce this risk.
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Affiliation(s)
- Marc-André Clément
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Canada
| | - Cristina R Bosoi
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Canada
| | - Mariana M Oliveira
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Canada
| | - Mélanie Tremblay
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Canada
| | - Chantal Bémeur
- 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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10
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Rose CF, Amodio P, Bajaj JS, Dhiman RK, Montagnese S, Taylor-Robinson SD, Vilstrup H, Jalan R. Hepatic encephalopathy: Novel insights into classification, pathophysiology and therapy. J Hepatol 2020; 73:1526-1547. [PMID: 33097308 DOI: 10.1016/j.jhep.2020.07.013] [Citation(s) in RCA: 183] [Impact Index Per Article: 45.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 07/01/2020] [Accepted: 07/03/2020] [Indexed: 02/07/2023]
Abstract
Hepatic encephalopathy (HE) is a frequent and serious complication of both chronic liver disease and acute liver failure. HE manifests as a wide spectrum of neuropsychiatric abnormalities, from subclinical changes (mild cognitive impairment) to marked disorientation, confusion and coma. The clinical and economic burden of HE is considerable, and it contributes greatly to impaired quality of life, morbidity and mortality. This review will critically discuss the latest classification of HE, as well as the pathogenesis and pathophysiological pathways underlying the neurological decline in patients with end-stage liver disease. In addition, management strategies, diagnostic approaches, currently available therapeutic options and novel treatment strategies are discussed.
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Affiliation(s)
- Christopher F Rose
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montreal, Canada.
| | - Piero Amodio
- Department of Medicine, University of Padova, Padova, Italy
| | - Jasmohan S Bajaj
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia, USA
| | - Radha Krishan Dhiman
- Department of Hepatology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | | | - Simon D Taylor-Robinson
- Department of Surgery and Cancer, St. Mary's Hospital Campus, Imperial College London, London, United Kingdom
| | - Hendrik Vilstrup
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Denmark
| | - Rajiv Jalan
- Liver Failure Group, Institute for Liver and Digestive Health, University College London, Royal Free Campus, London, United Kingdom; European Foundation for the Study of Chronic Liver Failure, Barcelona, Spain.
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Matoori S, Forster V, Agostoni V, Bettschart-Wolfensberger R, Bektas RN, Thöny B, Häberle J, Leroux JC, Kabbaj M. Preclinical evaluation of liposome-supported peritoneal dialysis for the treatment of hyperammonemic crises. J Control Release 2020; 328:503-513. [PMID: 32860926 DOI: 10.1016/j.jconrel.2020.08.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Revised: 08/07/2020] [Accepted: 08/20/2020] [Indexed: 12/19/2022]
Abstract
Liposome-supported peritoneal dialysis (LSPD) with transmembrane pH-gradient liposomes was previously shown to enhance ammonia removal in cirrhotic rats and holds promise for the treatment of hyperammonemic crises-associated disorders. The main objective of this work was to conduct the preclinical evaluation of LSPD in terms of pharmacokinetics, ammonia uptake, and toxicology to seek regulatory approval for a first-in-human study. The formulation containing citric acid-loaded liposomes was administered intraperitoneally at two different doses once daily for ten days to healthy minipigs. It was also tested in a domestic pig model of hyperammonemia. The pharmacokinetics of citric acid and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine was linear following intraperitoneal administration of medium and high dose. There was no systemic accumulation following daily doses over ten days. The systemic exposure to phospholipids remained low. Furthermore, the liposome-containing peritoneal fluid contained significantly higher ammonia levels than the liposome-free control, demonstrating efficient ammonia sequestration in the peritoneal space. This was indeed confirmed by the ability of LSPD to decrease plasmatic ammonia levels in artificially induced hyperammonemic pigs. LSPD was well tolerated, and no complement activation-related pseudoallergy reactions were observed. The safety profile, the linear pharmacokinetics of citric acid following repeated administrations of LSPD as well as the linear dose-dependent ammonia sequestration in the peritoneal space provide a strong basis for the clinical investigation of LSPD.
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Affiliation(s)
- Simon Matoori
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland; John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, USA
| | | | - Valentina Agostoni
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland
| | - Regula Bettschart-Wolfensberger
- Department of Clinical Diagnostics and Services, Section of Anaesthesiology, Vetsuisse Faculty University of Zurich, Zurich, Switzerland
| | - Rima Nadine Bektas
- Department of Clinical Diagnostics and Services, Section of Anaesthesiology, Vetsuisse Faculty University of Zurich, Zurich, Switzerland
| | - Beat Thöny
- Division of Metabolism, University Children's Hospital Zurich and Children's Research Centre, Zurich, Switzerland
| | - Johannes Häberle
- Division of Metabolism, University Children's Hospital Zurich and Children's Research Centre, Zurich, Switzerland
| | - Jean-Christophe Leroux
- Institute of Pharmaceutical Sciences, Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland.
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12
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Abstract
Despite widespread use of lactulose and rifaximin for the treatment of hepatic encephalopathy, this complication of advanced liver disease remains a major burden on the health care system in the United States and continues to predispose to high morbidity and mortality. Several agents have surfaced over recent years with promise to treat hepatic encephalopathy and mitigate the cognitive impairment associated with this disease process. The purpose of this article is to highlight the leading emerging therapies in hepatic encephalopathy as well as their therapeutic targets.
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13
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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: 19] [Impact Index Per Article: 4.8] [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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14
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De Chiara F, Thomsen KL, Habtesion A, Jones H, Davies N, Gracia-Sancho J, Manicardi N, Hall A, Andreola F, Paish HL, Reed LH, Watson AA, Leslie J, Oakley F, Rombouts K, Mookerjee RP, Mann J, Jalan R. Ammonia Scavenging Prevents Progression of Fibrosis in Experimental Nonalcoholic Fatty Liver Disease. Hepatology 2020; 71:874-892. [PMID: 31378982 DOI: 10.1002/hep.30890] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2019] [Accepted: 07/07/2019] [Indexed: 01/10/2023]
Abstract
BACKGROUND AND AIMS In nonalcoholic fatty liver disease (NAFLD), fibrosis is the most important factor contributing to NAFLD-associated morbidity and mortality. Prevention of progression and reduction in fibrosis are the main aims of treatment. Even in early stages of NAFLD, hepatic and systemic hyperammonemia is evident. This is due to reduced urea synthesis; and as ammonia is known to activate hepatic stellate cells, we hypothesized that ammonia may be involved in the progression of fibrosis in NAFLD. APPROACH AND RESULTS In a high-fat, high-cholesterol diet-induced rodent model of NAFLD, we observed a progressive stepwise reduction in the expression and activity of urea cycle enzymes resulting in hyperammonemia, evidence of hepatic stellate cell activation, and progressive fibrosis. In primary, cultured hepatocytes and precision-cut liver slices we demonstrated increased gene expression of profibrogenic markers after lipid and/or ammonia exposure. Lowering of ammonia with the ammonia scavenger ornithine phenylacetate prevented hepatocyte cell death and significantly reduced the development of fibrosis both in vitro in the liver slices and in vivo in a rodent model. The prevention of fibrosis in the rodent model was associated with restoration of urea cycle enzyme activity and function, reduced hepatic ammonia, and markers of inflammation. CONCLUSIONS The results of this study suggest that hepatic steatosis results in hyperammonemia, which is associated with progression of hepatic fibrosis. Reduction of ammonia levels prevented progression of fibrosis, providing a potential treatment for NAFLD.
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Affiliation(s)
- Francesco De Chiara
- UCL Institute of Liver and Digestive Health, University College London, London, UK
| | - Karen Louise Thomsen
- UCL Institute of Liver and Digestive Health, University College London, London, UK.,Department of Hepatology & Gastroenterology, Aarhus University Hospital, Aarhus, Denmark
| | - Abeba Habtesion
- UCL Institute of Liver and Digestive Health, University College London, London, UK
| | - Helen Jones
- UCL Institute of Liver and Digestive Health, University College London, London, UK
| | - Nathan Davies
- UCL Institute of Liver and Digestive Health, University College London, London, UK
| | - Jordi Gracia-Sancho
- Liver Vascular Biology Research Group, IDIBAPS Biomedical Research Institute & CIBEREHD, Barcelona, Spain
| | - Nicolò Manicardi
- Liver Vascular Biology Research Group, IDIBAPS Biomedical Research Institute & CIBEREHD, Barcelona, Spain
| | - Andrew Hall
- UCL Institute of Liver and Digestive Health, University College London, London, UK
| | - Fausto Andreola
- UCL Institute of Liver and Digestive Health, University College London, London, UK
| | - Hannah L Paish
- Newcastle Fibrosis Research Group, Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Lee H Reed
- Newcastle Fibrosis Research Group, Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Abigail A Watson
- Newcastle Fibrosis Research Group, Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Jack Leslie
- Newcastle Fibrosis Research Group, Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Fiona Oakley
- Newcastle Fibrosis Research Group, Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Krista Rombouts
- UCL Institute of Liver and Digestive Health, University College London, London, UK
| | | | - Jelena Mann
- Newcastle Fibrosis Research Group, Institute of Cellular Medicine, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK
| | - Rajiv Jalan
- UCL Institute of Liver and Digestive Health, University College London, London, UK
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15
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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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16
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Kim JY, Ri HS, Yoon JU, Choi EJ, Kim HJ, Park JY. Fatal neurological complication after liver transplantation in acute hepatic failure patient with hepatic encephalopathy. KOSIN MEDICAL JOURNAL 2018. [DOI: 10.7180/kmj.2018.33.1.96] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Liver transplantation is a current definitive treatment for those with end-stage liver disease. Hepatic encephalopathy is a common complication of hepatic failure, which can be improved and aggravated by various causes. It is important to differentiate hepatic encephalopathy from other diseases causing brain dysfunction such as cerebral hemorrhage, which is also related to high mortality after liver transplant surgery. A 37-year-old patient was presented with acute liver failure and high ammonia levels and seizure-like symptoms. Computed tomography (CT) of his brain showed mild brain atrophy, regarded as a symptom of hepatic encephalopathy, and treated to decrease blood ammonia level. Deceased donor liver transplantation was performed and liver function and ammonia level normalized after surgery, but the patient showed symptoms of involuntary muscle contraction and showed loss of pupil reflex and fixation without recovery of consciousness. Brain CT showed brain edema and bilateral cerebral infarction, and the patient died after a few days. The purpose of this case report is to emphasize the importance of preoperative neurological evaluation, careful transplantation decision, and proper perioperative management of liver transplantation in patients with acute hepatic encephalopathy.
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17
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Stravitz RT, Gottfried M, Durkalski V, Fontana RJ, Hanje AJ, Koch D, Hameed B, Ganger D, Subramanian RM, Bukofzer S, Ravis WR, Clasen K, Sherker A, Little L, Lee WM. Safety, tolerability, and pharmacokinetics of l-ornithine phenylacetate in patients with acute liver injury/failure and hyperammonemia. Hepatology 2018; 67:1003-1013. [PMID: 29080224 PMCID: PMC5826861 DOI: 10.1002/hep.29621] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Revised: 08/03/2017] [Accepted: 10/25/2017] [Indexed: 12/12/2022]
Abstract
Cerebral edema remains a significant cause of morbidity and mortality in patients with acute liver failure (ALF) and has been linked to elevated blood ammonia levels. l-ornithine phenylacetate (OPA) may decrease ammonia by promoting its renal excretion as phenylacetylglutamine (PAGN), decreasing the risk of cerebral edema. We evaluated the safety, tolerability, and pharmacokinetics of OPA in patients with ALF and acute liver injury (ALI), including those with renal failure. Forty-seven patients with ALI/ALF and ammonia ≥60 μM were enrolled. Patients received OPA in a dose escalation scheme from 3.3 g every 24 hours to 10 g every 24 hours; 15 patients received 20 g every 24 hours throughout the infusion for up to 120 hours. Plasma phenylacetate (PA) concentrations were uniformly below target (<75 μg/mL) in those receiving 3.3 g every 24 hours (median [interquartile range] 5.0 [5.0] μg/mL), and increased to target levels in all but one who received 20 g every 24 hours (150 [100] μg/mL). Plasma [PAGN] increased, and conversion of PA to PAGN became saturated, with increasing OPA dose. Urinary PAGN clearance and creatinine clearance were linearly related (r = 0.831, P < 0.0001). Mean ammonia concentrations based on the area under the curve decreased to a greater extent in patients who received 20 g of OPA every 24 hours compared with those who received the maximal dose of 3.3 or 6.7 g every 24 hours (P = 0.046 and 0.022, respectively). Of the reported serious adverse events (AEs), which included 11 deaths, none was attributable to study medication. The only nonserious AEs possibly related to study drug were headache and nausea/vomiting. CONCLUSION OPA was well-tolerated in patients with ALI/ALF, and no safety signals were identified. Target [PA] was achieved at infusion rates of 20 g every 24 hours, leading to ammonia excretion in urine as PAGN in proportion to renal function. Randomized, controlled studies of high-dose OPA are needed to determine its use as an ammonia-scavenging agent in patients with ALF. (Hepatology 2018;67:1003-1013).
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Affiliation(s)
| | | | | | | | | | - David Koch
- Medical University of South Carolina, Charleston, SC
| | - Bilal Hameed
- University of California at San Francisco, San Francisco, CA
| | | | | | | | | | | | - Averell Sherker
- National Institute of Diabetes, Digestive and Kidney Disease, Bethesda, MD
| | - Lanna Little
- University of Texas, Southwestern Medical Center, Dallas, TX
| | - William M. Lee
- University of Texas, Southwestern Medical Center, Dallas, TX
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18
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Thomsen KL, De Chiara F, Rombouts K, Vilstrup H, Andreola F, Mookerjee RP, Jalan R. Ammonia: A novel target for the treatment of non-alcoholic steatohepatitis. Med Hypotheses 2018. [PMID: 29523305 DOI: 10.1016/j.mehy.2018.02.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Non-alcoholic fatty liver disease (NAFLD) is a spectrum of liver diseases ranging from steatosis, through non-alcoholic steatohepatitis (NASH) to cirrhosis. The development of fibrosis is the most important factor contributing to NASH-associated morbidity and mortality. Hepatic stellate cells (HSCs) are responsible for extracellular matrix deposition in conditions of frank hepatocellular injury and are key cells involved in the development of fibrosis. In experimental models and patients with NASH, urea cycle enzyme gene and protein expression is reduced resulting in functional reduction in the in vivo capacity for ureagenesis and subsequent hyperammonemia at a pre-cirrhotic stage. Ammonia has been shown to activate HSCs in vivo and in vitro. Hyperammonemia in the context of NASH may therefore favour the progression of fibrosis and the disease. We therefore hypothesise that ammonia is a potential target for prevention of fibrosis progression of patients with NASH.
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Affiliation(s)
- Karen Louise Thomsen
- UCL Institute for Liver and Digestive Health, University College London, United Kingdom; Department of Hepatology & Gastroenterology, Aarhus University Hospital, Denmark
| | - Francesco De Chiara
- UCL Institute for Liver and Digestive Health, University College London, United Kingdom
| | - Krista Rombouts
- UCL Institute for Liver and Digestive Health, University College London, United Kingdom
| | - Hendrik Vilstrup
- Department of Hepatology & Gastroenterology, Aarhus University Hospital, Denmark
| | - Fausto Andreola
- UCL Institute for Liver and Digestive Health, University College London, United Kingdom
| | - Rajeshwar P Mookerjee
- UCL Institute for Liver and Digestive Health, University College London, United Kingdom
| | - Rajiv Jalan
- UCL Institute for Liver and Digestive Health, University College London, United Kingdom.
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19
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Hadjihambi A, Arias N, Sheikh M, Jalan R. Hepatic encephalopathy: a critical current review. Hepatol Int 2017; 12:135-147. [PMID: 28770516 PMCID: PMC5830466 DOI: 10.1007/s12072-017-9812-3] [Citation(s) in RCA: 109] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Accepted: 07/06/2017] [Indexed: 12/12/2022]
Abstract
Hepatic encephalopathy (HE) is a serious neuropsychiatric complication of cirrhosis and/or porto-systemic shunting. The clinical symptoms are widely variable, extending from subtle impairment in mental state to coma. The utility of categorizing the severity of HE accurately and efficiently serves not only to provide practical functional information about the current clinical status of the patient but also gives valuable prognostic information. In the past 20–30 years, there has been rapid progress in understanding the pathophysiological basis of HE; however, the lack of direct correlation between pathogenic factors and the severity of HE make it difficult to select appropriate therapy for HE patients. In this review, we will discuss the classification system and its limitations, the neuropsychometric assessments and their challenges, as well as the present knowledge on the pathophysiological mechanisms. Despite the many prevalent hypotheses around the pathogenesis of the disease, most treatments focus on targeting and lowering the accumulation of ammonia as well as inflammation. However, treatment of minimal HE remains a huge unmet need and a big concerted effort is needed to better define this condition to allow the development of new therapies. We review the currently available therapies and future approaches to treat HE as well as the scientific and clinical data that support their effectiveness.
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Affiliation(s)
- Anna Hadjihambi
- Division of Medicine, UCL Medical School, Royal Free Hospital, UCL Institute for Liver and Digestive Health, Rowland Hill Street, London, NW3 2PF, UK.,Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and Pharmacology, University College London, London, WC1E 6BT, UK
| | - Natalia Arias
- Division of Medicine, UCL Medical School, Royal Free Hospital, UCL Institute for Liver and Digestive Health, Rowland Hill Street, London, NW3 2PF, UK.,INEUROPA (Instituto de Neurociencias del Principado de Asturias), Oviedo, Spain
| | - Mohammed Sheikh
- Division of Medicine, UCL Medical School, Royal Free Hospital, UCL Institute for Liver and Digestive Health, Rowland Hill Street, London, NW3 2PF, UK
| | - Rajiv Jalan
- Division of Medicine, UCL Medical School, Royal Free Hospital, UCL Institute for Liver and Digestive Health, Rowland Hill Street, London, NW3 2PF, UK.
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20
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de las Heras J, Aldámiz-Echevarría L, Martínez-Chantar ML, Delgado TC. An update on the use of benzoate, phenylacetate and phenylbutyrate ammonia scavengers for interrogating and modifying liver nitrogen metabolism and its implications in urea cycle disorders and liver disease. Expert Opin Drug Metab Toxicol 2017; 13:439-448. [PMID: 27860485 PMCID: PMC5568887 DOI: 10.1080/17425255.2017.1262843] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
INTRODUCTION Ammonia-scavenging drugs, benzoate and phenylacetate (PA)/phenylbutyrate (PB), modulate hepatic nitrogen metabolism mainly by providing alternative pathways for nitrogen disposal. Areas covered: We review the major findings and potential novel applications of ammonia-scavenging drugs, focusing on urea cycle disorders and liver disease. Expert opinion: For over 40 years, ammonia-scavenging drugs have been used in the treatment of urea cycle disorders. Recently, the use of these compounds has been advocated in acute liver failure and cirrhosis for reducing hyperammonemic-induced hepatic encephalopathy. The efficacy and mechanisms underlying the antitumor effects of these ammonia-scavenging drugs in liver cancer are more controversial and are discussed in the review. Overall, as ammonia-scavenging drugs are usually safe and well tolerated among cancer patients, further studies should be instigated to explore the role of these drugs in liver cancer. Considering the relevance of glutamine metabolism to the progression and resolution of liver disease, we propose that ammonia-scavenging drugs might also be used to non-invasively probe liver glutamine metabolism in vivo. Finally, novel derivatives of classical ammonia-scavenging drugs with fewer and less severe adverse effects are currently being developed and used in clinical trials for the treatment of acute liver failure and cirrhosis.
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Affiliation(s)
- Javier de las Heras
- Division of Pediatric Metabolism, University Hospital of Cruces, Barakaldo, Bizkaia, Spain
- BioCruces Health Research Institute, Barakaldo, Bizkaia, Spain
- University of the Basque Country, Leioa, Bizkaia, Spain
| | - Luis Aldámiz-Echevarría
- Division of Pediatric Metabolism, University Hospital of Cruces, Barakaldo, Bizkaia, Spain
- BioCruces Health Research Institute, Barakaldo, Bizkaia, Spain
- University of the Basque Country, Leioa, Bizkaia, Spain
| | - María-Luz Martínez-Chantar
- University of the Basque Country, Leioa, Bizkaia, Spain
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Derio, Bizkaia, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Derio, Bizkaia, Spain
| | - Teresa C. Delgado
- Center for Cooperative Research in Biosciences (CIC bioGUNE), Derio, Bizkaia, Spain
- Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Derio, Bizkaia, Spain
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21
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Hadjihambi A, De Chiara F, Hosford PS, Habtetion A, Karagiannis A, Davies N, Gourine AV, Jalan R. Ammonia mediates cortical hemichannel dysfunction in rodent models of chronic liver disease. Hepatology 2017; 65:1306-1318. [PMID: 28066916 PMCID: PMC5396295 DOI: 10.1002/hep.29031] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Revised: 11/22/2016] [Accepted: 12/23/2016] [Indexed: 12/19/2022]
Abstract
UNLABELLED The pathogenesis of hepatic encephalopathy (HE) in cirrhosis is multifactorial and ammonia is thought to play a key role. Astroglial dysfunction is known to be present in HE. Astrocytes are extensively connected by gap junctions formed of connexins, which also exist as functional hemichannels allowing exchange of molecules between the cytoplasm and the extracellular milieu. The astrocyte-neuron lactate shuttle hypothesis suggests that neuronal activity is fueled (at least in part) by lactate provided by neighboring astrocytes. We hypothesized that in HE, astroglial dysfunction could impair metabolic communication between astrocytes and neurons. In this study, we determined whether hyperammonemia leads to hemichannel dysfunction and impairs lactate transport in the cerebral cortex using rat models of HE (bile duct ligation [BDL] and induced hyperammonemia) and also evaluated the effect of ammonia-lowering treatment (ornithine phenylacetate [OP]). Plasma ammonia concentration in BDL rats was significantly reduced by OP treatment. Biosensor recordings demonstrated that HE is associated with a significant reduction in both tonic and hypoxia-induced lactate release in the cerebral cortex, which was normalized by OP treatment. Cortical dye loading experiments revealed hemichannel dysfunction in HE with improvement following OP treatment, while the expression of key connexins was unaffected. CONCLUSION The results of the present study demonstrate that HE is associated with central nervous system hemichannel dysfunction, with ammonia playing a key role. The data provide evidence of a potential neuronal energy deficit due to impaired hemichannel-mediated lactate transport between astrocytes and neurons as a possible mechanism underlying pathogenesis of HE. (Hepatology 2017;65:1306-1318).
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Affiliation(s)
- Anna Hadjihambi
- UCL Institute for Liver and Digestive Health, Division of Medicine, UCL Medical School, Royal Free HospitalRowland Hill StreetLondonUnited Kingdom,Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and PharmacologyUniversity College LondonLondonUnited Kingdom
| | - Francesco De Chiara
- UCL Institute for Liver and Digestive Health, Division of Medicine, UCL Medical School, Royal Free HospitalRowland Hill StreetLondonUnited Kingdom
| | - Patrick S. Hosford
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and PharmacologyUniversity College LondonLondonUnited Kingdom
| | - Abeba Habtetion
- UCL Institute for Liver and Digestive Health, Division of Medicine, UCL Medical School, Royal Free HospitalRowland Hill StreetLondonUnited Kingdom
| | | | - Nathan Davies
- UCL Institute for Liver and Digestive Health, Division of Medicine, UCL Medical School, Royal Free HospitalRowland Hill StreetLondonUnited Kingdom
| | - Alexander V. Gourine
- Centre for Cardiovascular and Metabolic Neuroscience, Neuroscience, Physiology and PharmacologyUniversity College LondonLondonUnited Kingdom
| | - Rajiv Jalan
- UCL Institute for Liver and Digestive Health, Division of Medicine, UCL Medical School, Royal Free HospitalRowland Hill StreetLondonUnited Kingdom
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22
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Jalan R. Novel therapies in the management of acute episodes of hepatic encephalopathy. Clin Liver Dis (Hoboken) 2017; 9:66-68. [PMID: 30992961 PMCID: PMC6467145 DOI: 10.1002/cld.620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2016] [Revised: 01/01/2017] [Accepted: 01/09/2017] [Indexed: 02/04/2023] Open
Affiliation(s)
- Rajiv Jalan
- Liver Failure Group, Institute for Liver and Digestive HealthUniversity College LondonLondonUnited Kingdom
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23
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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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24
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Kristiansen RG. Current state of knowledge of hepatic encephalopathy (part I): newer treatment strategies for hyperammonemia in liver failure. Metab Brain Dis 2016; 31:1357-1358. [PMID: 27651377 DOI: 10.1007/s11011-016-9908-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Accepted: 09/05/2016] [Indexed: 01/27/2023]
Abstract
Alterations in interorgan metabolism of ammonia play an important role in the onset of hyperammonemia in liver failure. Glutamine synthetase (GS) in muscle is an important target for ammonia removal strategies in hyperammonemia. Ornithine Phenylacetate (OP) is hypothesized to remove ammonia by providing glutamate as a substrate for increased GS activity and hence glutamine production. The newly generated glutamine conjugates with phenylacetate forming phenylacetylglutamine which can be excreted in the urine, providing an excretion pathway for ammonia. We have also shown that OP targets glycine metabolism, providing an additional ammonia reducing effect.
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Affiliation(s)
- Rune Gangsoy Kristiansen
- Department of Anesthesiology, Anesthesia and Critical Care Research Group, University Hospital of North Norway, UiT-The Arctic University of Norway, Tromsø, Norway.
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Milewski K, Oria M. What we know: the inflammatory basis of hepatic encephalopathy. Metab Brain Dis 2016; 31:1239-1247. [PMID: 26497651 DOI: 10.1007/s11011-015-9740-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 09/24/2015] [Indexed: 02/07/2023]
Abstract
Central Nervous System (CNS) degeneration appearing in patients with cirrhosis is responsible for cognitive and persistent motor impairments that lead to an important impact on life quality. Brain injury affects certain areas of the CNS that might affect two types of cells: neurons and astrocytes. The process leading to brain injury could be induced by portosystemic shunting accompanied by hyperammonemia and by the activation of peripheral inflammation, manifested as episodic encephalopathy. Hyperammonemia combined with a decrease on the BCA/AAA ratio induces alterations of energetic metabolism and the formation of free radicals in the CNS. This process would be stimulated by the activation of peripheral inflammatory mediators that could act on receptors of the blood brain barrier such as TLR4, activating inflammatory responses in the CNS. As a result, a persistent activation of microglia and an irreversible neuronal and astrocytic injury would be induced. A new knowledge of the mechanisms leading to brain injury in cirrhosis would develop protective strategies to correct changes of nitrogen metabolism and inflammation.
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Affiliation(s)
- K Milewski
- Department of Neurotoxicology, Mossakowski Medical Research Centre, Polish Academy of Sciences, Pawińskiego 5 Str, 02-106, Warsaw, Poland
| | - M Oria
- Translational Research in Fetal Surgery for Congenital Malformations, Center for Fetal, Cellular and Molecular Therapy, Division of Pediatric General and Thoracic Surgery, Cincinnati Children's Hospital Medical Center (CCHMC), 3333 Burnet Avenue, MLC 11020, S 8.400 AT, Cincinnati, OH, 45229-3039, USA.
- Liver Failure Group, UCL Institute for Liver and Digestive Health, Royal Free Hospital, University College London, London, UK.
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Kristiansen RG, Rose CF, Ytrebø LM. Glycine and hyperammonemia: potential target for the treatment of hepatic encephalopathy. Metab Brain Dis 2016; 31:1269-1273. [PMID: 27339764 DOI: 10.1007/s11011-016-9858-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 06/12/2016] [Indexed: 01/10/2023]
Abstract
Hepatic encephalopathy (HE) is a neuropsychiatric disorder caused by hepatic dysfunction. Numerous studies dictate that ammonia plays an important role in the pathogenesis of HE, and hyperammonemia can lead to alterations in amino acid homeostasis. Glutamine and glycine are both ammoniagenic amino acids that are increased in liver failure. Modulating the levels of glutamine and glycine has shown to reduce ammonia concentration in hyperammonemia. Ornithine Phenylacetate (OP) has consistently been shown to reduce arterial ammonia levels in liver failure by modulating glutamine levels. In addition to this, OP has also been found to modulate glycine concentration providing an additional ammonia removing effect. Data support that glycine also serves an important role in N-methyl D-aspartate (NMDA) receptor mediated neurotransmission in HE. This potential important role for glycine in the pathogenesis of HE merits further investigations.
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Affiliation(s)
- Rune Gangsøy Kristiansen
- Department of Anesthesiology, Anesthesia and Critical Care Research Group, University Hospital of North Norway and UiT-The Arctic University of Norway, Tromsø, Norway.
- Department of Anesthesiology, Ålesund Hospital, Helse Møre og Romsdal, 6010, Ålesund, Norway.
| | - Christopher F Rose
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, QC, Canada
| | - Lars Marius Ytrebø
- Department of Anesthesiology, Anesthesia and Critical Care Research Group, University Hospital of North Norway and UiT-The Arctic University of Norway, Tromsø, Norway
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Rombouts K, Bémeur C, Rose CF. Targeting the muscle for the treatment and prevention of hepatic encephalopathy. J Hepatol 2016; 65:876-878. [PMID: 27590353 DOI: 10.1016/j.jhep.2016.08.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 08/23/2016] [Accepted: 08/25/2016] [Indexed: 02/09/2023]
Affiliation(s)
- Krista Rombouts
- University College London (UCL), Institute for Liver & Digestive Health, Royal Free Hospital, London, United Kingdom.
| | - Chantal Bémeur
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Quebec, Canada; Département de Nutrition, Faculté de Médecine, Université de Montréal, Montréal, Quebec, Canada.
| | - Christopher F Rose
- Hepato-Neuro Laboratory, CRCHUM, Université de Montréal, Montréal, Quebec, Canada.
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Davuluri G, Allawy A, Thapaliya S, Rennison JH, Singh D, Kumar A, Sandlers Y, Van Wagoner DR, Flask CA, Hoppel C, Kasumov T, Dasarathy S. Hyperammonaemia-induced skeletal muscle mitochondrial dysfunction results in cataplerosis and oxidative stress. J Physiol 2016; 594:7341-7360. [PMID: 27558544 DOI: 10.1113/jp272796] [Citation(s) in RCA: 108] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 08/12/2016] [Indexed: 12/18/2022] Open
Abstract
KEY POINTS Hyperammonaemia occurs in hepatic, cardiac and pulmonary diseases with increased muscle concentration of ammonia. We found that ammonia results in reduced skeletal muscle mitochondrial respiration, electron transport chain complex I dysfunction, as well as lower NAD+ /NADH ratio and ATP content. During hyperammonaemia, leak of electrons from complex III results in oxidative modification of proteins and lipids. Tricarboxylic acid cycle intermediates are decreased during hyperammonaemia, and providing a cell-permeable ester of αKG reversed the lower TCA cycle intermediate concentrations and increased ATP content. Our observations have high clinical relevance given the potential for novel approaches to reverse skeletal muscle ammonia toxicity by targeting the TCA cycle intermediates and mitochondrial ROS. ABSTRACT Ammonia is a cytotoxic metabolite that is removed primarily by hepatic ureagenesis in humans. Hyperammonaemia occurs in advanced hepatic, cardiac and pulmonary disease, and in urea cycle enzyme deficiencies. Increased skeletal muscle ammonia uptake and metabolism are the major mechanism of non-hepatic ammonia disposal. Non-hepatic ammonia disposal occurs in the mitochondria via glutamate synthesis from α-ketoglutarate resulting in cataplerosis. We show skeletal muscle mitochondrial dysfunction during hyperammonaemia in a comprehensive array of human, rodent and cellular models. ATP synthesis, oxygen consumption, generation of reactive oxygen species with oxidative stress, and tricarboxylic acid (TCA) cycle intermediates were quantified. ATP content was lower in the skeletal muscle from cirrhotic patients, hyperammonaemic portacaval anastomosis rat, and C2C12 myotubes compared to appropriate controls. Hyperammonaemia in C2C12 myotubes resulted in impaired intact cell respiration, reduced complex I/NADH oxidase activity and electron leak occurring at complex III of the electron transport chain. Consistently, lower NAD+ /NADH ratio was observed during hyperammonaemia with reduced TCA cycle intermediates compared to controls. Generation of reactive oxygen species resulted in increased content of skeletal muscle carbonylated proteins and thiobarbituric acid reactive substances during hyperammonaemia. A cell-permeable ester of α-ketoglutarate reversed the low TCA cycle intermediates and ATP content in myotubes during hyperammonaemia. However, the mitochondrial antioxidant MitoTEMPO did not reverse the lower ATP content during hyperammonaemia. We provide for the first time evidence that skeletal muscle hyperammonaemia results in mitochondrial dysfunction and oxidative stress. Use of anaplerotic substrates to reverse ammonia-induced mitochondrial dysfunction is a novel therapeutic approach.
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Affiliation(s)
- Gangarao Davuluri
- Department of Pathobiology, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Allawy Allawy
- Department of Pathobiology, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Samjhana Thapaliya
- Department of Pathobiology, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Julie H Rennison
- Department of Pathobiology, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Dharmvir Singh
- Department of Pathobiology, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Avinash Kumar
- Department of Pathobiology, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Yana Sandlers
- Department of Chemistry, Cleveland State University, SR 364, 2351 Euclid Avenue, Cleveland, OH, 44115, USA
| | - David R Van Wagoner
- Department of Molecular Cardiology, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
| | - Chris A Flask
- Department of Biomedical Engineering, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Charles Hoppel
- Department of Pharmacology and Medicine, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH, 44106, USA
| | - Takhar Kasumov
- Department of Pharmaceutical Sciences, Northeast Ohio Medical University, 4209 State Route 44, Rootstown, OH, 44272
| | - Srinivasan Dasarathy
- Department of Pathobiology, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA.,Department of Gastroenterology, Cleveland Clinic, 9500 Euclid Avenue, Cleveland, OH, 44195, USA
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Jalan R, De Chiara F, Balasubramaniyan V, Andreola F, Khetan V, Malago M, Pinzani M, Mookerjee RP, Rombouts K. Ammonia produces pathological changes in human hepatic stellate cells and is a target for therapy of portal hypertension. J Hepatol 2016; 64:823-33. [PMID: 26654994 DOI: 10.1016/j.jhep.2015.11.019] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Revised: 11/09/2015] [Accepted: 11/11/2015] [Indexed: 12/14/2022]
Abstract
BACKGROUND & AIMS Hepatic stellate cells (HSCs) are vital to hepatocellular function and the liver response to injury. They share a phenotypic homology with astrocytes that are central in the pathogenesis of hepatic encephalopathy, a condition in which hyperammonemia plays a pathogenic role. This study tested the hypothesis that ammonia modulates human HSC activation in vitro and in vivo, and evaluated whether ammonia lowering, by using l-ornithine phenylacetate (OP), modifies HSC activation in vivo and reduces portal pressure in a bile duct ligation (BDL) model. METHODS Primary human HSCs were isolated and cultured. Proliferation (BrdU), metabolic activity (MTS), morphology (transmission electron, light and immunofluorescence microscopy), HSC activation markers, ability to contract, changes in oxidative status (ROS) and endoplasmic reticulum (ER) were evaluated to identify effects of ammonia challenge (50 μM, 100 μM, 300 μM) over 24-72 h. Changes in plasma ammonia levels, markers of HSC activation, portal pressure and hepatic eNOS activity were quantified in hyperammonemic BDL animals, and after OP treatment. RESULTS Pathophysiological ammonia concentrations caused significant and reversible changes in cell proliferation, metabolic activity and activation markers of hHSC in vitro. Ammonia also induced significant alterations in cellular morphology, characterised by cytoplasmic vacuolisation, ER enlargement, ROS production, hHSC contraction and changes in pro-inflammatory gene expression together with HSC-related activation markers such as α-SMA, myosin IIa, IIb, and PDGF-Rβ. Treatment with OP significantly reduced plasma ammonia (BDL 199.1 μmol/L±43.65 vs. BDL+OP 149.27 μmol/L±51.1, p<0.05) and portal pressure (BDL 14±0.6 vs. BDL+OP 11±0.3 mmHg, p<0.01), which was associated with increased eNOS activity and abrogation of HSC activation markers. CONCLUSIONS The results show for the first time that ammonia produces deleterious morphological and functional effects on HSCs in vitro. Targeting ammonia with the ammonia lowering drug OP reduces portal pressure and deactivates hHSC in vivo, highlighting the opportunity for evaluating ammonia lowering as a potential therapy in cirrhotic patients with portal hypertension.
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Affiliation(s)
- Rajiv Jalan
- Liver Failure Group, Institute for Liver & Digestive Health, University College of London, Royal Free, London, UK
| | - Francesco De Chiara
- Liver Failure Group, Institute for Liver & Digestive Health, University College of London, Royal Free, London, UK
| | - Vairappan Balasubramaniyan
- Liver Failure Group, Institute for Liver & Digestive Health, University College of London, Royal Free, London, UK
| | - Fausto Andreola
- Liver Failure Group, Institute for Liver & Digestive Health, University College of London, Royal Free, London, UK
| | - Varun Khetan
- Liver Failure Group, Institute for Liver & Digestive Health, University College of London, Royal Free, London, UK
| | - Massimo Malago
- Division of Surgery, University College London, Royal Free, London, UK
| | - Massimo Pinzani
- Regenerative Medicine & Fibrosis Group, Institute for Liver & Digestive Health, University College London, Royal Free, London, UK
| | - Rajeshwar P Mookerjee
- Liver Failure Group, Institute for Liver & Digestive Health, University College of London, Royal Free, London, UK.
| | - Krista Rombouts
- Regenerative Medicine & Fibrosis Group, Institute for Liver & Digestive Health, University College London, Royal Free, London, UK.
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Chen L, Cui H. Targeting Glutamine Induces Apoptosis: A Cancer Therapy Approach. Int J Mol Sci 2015; 16:22830-55. [PMID: 26402672 PMCID: PMC4613338 DOI: 10.3390/ijms160922830] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Revised: 09/11/2015] [Accepted: 09/15/2015] [Indexed: 02/06/2023] Open
Abstract
Glutamine metabolism has been proved to be dysregulated in many cancer cells, and is essential for proliferation of most cancer cells, which makes glutamine an appealing target for cancer therapy. In order to be well used by cells, glutamine must be transported to cells by specific transporters and converted to glutamate by glutaminase. There are currently several drugs that target glutaminase under development or clinical trials. Also, glutamine metabolism restriction has been proved to be effective in inhibiting tumor growth both in vivo and vitro through inducing apoptosis, growth arrest and/or autophagy. Here, we review recent researches about glutamine metabolism in cancer, and cell death induced by targeting glutamine, and their potential roles in cancer therapy.
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Affiliation(s)
- Lian Chen
- Key Laboratory of Animal Diseases and Environmental Hazards of Sichuan Province, Sichuan Agriculture University, Ya'an 625014, China.
| | - Hengmin Cui
- Key Laboratory of Animal Diseases and Environmental Hazards of Sichuan Province, Sichuan Agriculture University, Ya'an 625014, China.
- College of Veterinary Medicine, Sichuan Agricultural University, Ya'an 625014, China.
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Abstract
Normal regulation of total body and circulating ammonia requires a delicate interplay in ammonia formation and breakdown between several organ systems. In the setting of cirrhosis and portal hypertension, the decreased hepatic clearance of ammonia leads to significant dependence on skeletal muscle for ammonia detoxification; however, cirrhosis is also associated with muscle depletion and decreased functional muscle mass. Thus, patients with diminished muscle mass and sarcopenia may have a decreased ability to compensate for hepatic insufficiency and a higher likelihood of developing physiologically significant hyperammonemia and hepatic encephalopathy.
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Affiliation(s)
- Catherine Lucero
- Division of Digestive and Liver Diseases, Department of Medicine, Center for Liver Disease and Transplantation, Columbia University College of Physicians and Surgeons, 622 West 168th Street, PH 14-105, New York, NY 10032, USA
| | - Elizabeth C Verna
- Division of Digestive and Liver Diseases, Department of Medicine, Center for Liver Disease and Transplantation, Columbia University College of Physicians and Surgeons, 622 West 168th Street, PH 14-105, New York, NY 10032, USA.
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32
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Matoori S, Leroux JC. Recent advances in the treatment of hyperammonemia. Adv Drug Deliv Rev 2015; 90:55-68. [PMID: 25895618 DOI: 10.1016/j.addr.2015.04.009] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 03/30/2015] [Accepted: 04/13/2015] [Indexed: 02/07/2023]
Abstract
Ammonia is a neurotoxic agent that is primarily generated in the intestine and detoxified in the liver. Toxic increases in systemic ammonia levels predominantly result from an inherited or acquired impairment in hepatic detoxification and lead to potentially life-threatening neuropsychiatric symptoms. Inborn deficiencies in ammonia detoxification mainly affect the urea cycle, an endogenous metabolic removal system in the liver. Hepatic encephalopathy, on the other hand, is a hyperammonemia-related complication secondary to acquired liver function impairment. A range of therapeutic options is available to target either ammonia generation and absorption or ammonia removal. Therapies for hepatic encephalopathy decrease intestinal ammonia production and uptake. Treatments for urea cycle disorders eliminate ammoniagenic amino acids through metabolic transformation, preventing ammonia generation. Therapeutic approaches removing ammonia activate the urea cycle or the second essential endogenous ammonia detoxification system, glutamine synthesis. Recent advances in treating hyperammonemia include using synergistic combination treatments, broadening the indication of orphan drugs, and developing novel approaches to regenerate functional liver tissue. This manuscript reviews the various pharmacological treatments of hyperammonemia and focuses on biopharmaceutical and drug delivery issues.
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Affiliation(s)
- Anna Hadjihambi
- Institute for Liver and Digestive Health, Liver Failure Group, University College London Medical School Royal Free CampusLondonUK
| | - Rajiv Jalan
- Institute for Liver and Digestive Health, Liver Failure Group, University College London Medical School Royal Free CampusLondonUK
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Neuroprotection in acute brain injury: an up-to-date review. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2015; 19:186. [PMID: 25896893 PMCID: PMC4404577 DOI: 10.1186/s13054-015-0887-8] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Neuroprotective strategies that limit secondary tissue loss and/or improve functional outcomes have been identified in multiple animal models of ischemic, hemorrhagic, traumatic and nontraumatic cerebral lesions. However, use of these potential interventions in human randomized controlled studies has generally given disappointing results. In this paper, we summarize the current status in terms of neuroprotective strategies, both in the immediate and later stages of acute brain injury in adults. We also review potential new strategies and highlight areas for future research.
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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: 79] [Impact Index Per Article: 8.8] [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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Shalimar, Acharya SK. Management in acute liver failure. J Clin Exp Hepatol 2015; 5:S104-15. [PMID: 26041950 PMCID: PMC4442864 DOI: 10.1016/j.jceh.2014.11.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2014] [Accepted: 11/26/2014] [Indexed: 12/12/2022] Open
Abstract
Acute liver failure (ALF) is a rare, potentially fatal complication of severe hepatic illness resulting from various causes. In a clinical setting, severe hepatic injury is usually recognised by the appearance of jaundice, encephalopathy and coagulopathy. The central and most important clinical event in ALF is occurrence of hepatic encephalopathy (HE) and cerebral edema which is responsible for most of the fatalities in this serious clinical syndrome. The pathogenesis of encephalopathy and cerebral edema in ALF is unique and multifactorial. Ammonia plays a central role in the pathogenesis. The role of newer ammonia lowering agents is still evolving. Liver transplant is the only effective therapy that has been identified to be of promise in those with poor prognostic factors, whereas in the others, aggressive intensive medical management has been documented to salvage a substantial proportion of patients. A small fraction of patients undergo liver transplant and the remaining are usually treated with medical therapy. Therefore, identification of the complications and causes of death in such patients, and use of appropriate prognostic models to identify those who need liver transplant and those who can be managed with medical treatment is a vital component of therapeutic strategy. In this review, we discuss the various pathogenetic mechanisms and treatment options available.
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Key Words
- AASLD, American Association For the Study of Liver
- ALF, Acute Liver Failure
- ALFED, Acute Liver Failure Early Dynamic Model
- BBB, Blood Brain Barrier
- BCAA, Branched Chain Amino acid
- CBF, Cerebral Blood Flow
- CPP, Cerebral Perfusion Pressure
- CVVHD, Continuous Veno-Venous Hemodialysis
- FFP, Fresh Frozen Plasma
- GM-CSF, Granulocyte Macrophage Colony Stimulating Factor
- HE, Hepatic Encephalopathy
- ICU, Intensive Care Unit
- IEI, Icterus Encephalopathy Interval
- IL-1β, Interleukin-1 beta
- IL6, Interlekin 6
- INR, International Normalized Ratio
- LOLA, l-Ornithine L Aspartate
- LOPA
- LOPA, l-Ornithine Phenyl Acetate
- MAP, Mean Arterial Pressure
- NAC, N-Acetyl Cysteine
- NO, Nitric Oxide
- OLT, Orthotopic Liver Transplantation
- PCWP, Pulmonary Capillary Wedge Pressure
- PEEP, Positive End Expiratory Pressure
- PT, Prothrombin Time
- SIMV, Synchronous Intermittent mandatory Ventilation
- SIRS, Systemic Inflammatory Response Syndrome
- SPEAR, Selective Parenteral and Enteral Antibiotic Regimen
- TNF-α, Tumor Necrosis Factor alfa
- UCD, Urea Cycle Disorder
- USALF, United States Acute liver Failure Study Group
- ammonia
- cerebral edema
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Affiliation(s)
| | - Subrat K. Acharya
- Address for correspondence: Subrat K. Acharya, Department of Gastroenterology, All India Institute of Medical Sciences, New Delhi 110029, India.
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Saracyn M, Brytan M, Zdanowski R, Ząbkowski T, Dyrla P, Patera J, Wojtuń S, Kozłowski W, Wańkowicz Z. Hepatoprotective effect of nitric oxide in experimental model of acute hepatic failure. World J Gastroenterol 2014; 20:17407-17415. [PMID: 25516652 PMCID: PMC4265599 DOI: 10.3748/wjg.v20.i46.17407] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/05/2014] [Revised: 07/08/2014] [Accepted: 09/05/2014] [Indexed: 02/06/2023] Open
Abstract
AIM: To evaluate the effect of nitric oxide (NO) on the development and degree of liver failure in an animal model of acute hepatic failure (AHF).
METHODS: An experimental rat model of galactosamine-induced AHF was used. An inhibitor of NO synthase, nitroarginine methyl ester, or an NO donor, arginine, were administered at various doses prior to or after the induction of AHF.
RESULTS: All tested groups developed AHF. Following inhibition of the endogenous NO pathway, most liver parameters improved, regardless of the inhibitor dose before the induction of liver damage, and depending on the inhibitor dose after liver damage. Prophylactic administration of the inhibitor was more effective in improving liver function parameters than administration of the inhibitor after liver damage. An attempt to activate the endogenous NO pathway prior to the induction of liver damage did not change the observed liver function parameters. Stimulation of the endogenous NO pathway after liver damage, regardless of the NO donor dose used, improved most liver function parameters.
CONCLUSION: The endogenous NO pathway plays an important role in the development of experimental galactosamine-induced AHF.
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Abstract
INTRODUCTION Hepatic encephalopathy (HE) is a serious neuropsychiatric complication that is seen in patients with liver failure. The pathogenesis of HE is not entirely understood, but several hypotheses have emerged and persisted during the years. Despite the many prevalent hypotheses, most of the existing evidence point to ammonia as the main culprit behind primary and secondary symptoms making it the center of potential therapeutic options for the treatment of HE. Most treatments of hyperammonemia target the organs and metabolic processes involved in ammonia detoxification. AREAS COVERED This article provides a review of the current targets of therapy as well as the drugs used for hyperammonemia treatment. EXPERT OPINION Lactulose and rifaximin have a proven role as measures to use for secondary prophylaxis and are the mainstay of current therapy. The use of molecular adsorbent recirculating system in patients with severe HE has been proven to be efficacious, but through mechanisms that appear to be independent of ammonia. The main challenge that faces the further development of treatments for HE is finding appropriate end points, and the next step would be to provide evidence of the effectiveness of established treatments and define the role of emerging new treatments.
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Affiliation(s)
- Anna Hadjihambi
- UCL Institute for Liver and Digestive Health, UCL Medical School , Upper Third Floor, Royal Free Campus, Pond Street, NW3 2PF, London , UK +44 207 4332 794 ;
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Kristiansen RG, Rose CF, Fuskevåg OM, Mæhre H, Revhaug A, Jalan R, Ytrebø LM. L-Ornithine phenylacetate reduces ammonia in pigs with acute liver failure through phenylacetylglycine formation: a novel ammonia-lowering pathway. Am J Physiol Gastrointest Liver Physiol 2014; 307:G1024-31. [PMID: 25258408 DOI: 10.1152/ajpgi.00244.2014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Glycine is an important ammoniagenic amino acid, which is increased in acute liver failure (ALF). We have previously shown that L-ornithine phenylacetate (OP) attenuates ammonia rise and intracranial pressure in pigs suffering from ALF but failed to demonstrate a stoichiometric relationship between change in plasma ammonia levels and excretion of phenylacetylglutamine in urine. The aim was to investigate the impact of OP treatment on the phenylacetylglycine pathway as an alternative and additional ammonia-lowering pathway. A well-validated and -characterized large porcine model of ALF (portacaval anastomosis, followed by hepatic artery ligation), which recapitulates the cardinal features of human ALF, was used. Twenty-four female pigs were randomized into three groups: (1) sham operated + vehicle, (2) ALF + vehicle, and (3) ALF + OP. There was a significant increase in arterial glycine concentration in ALF (P < 0.001 compared with sham), with a three-fold increase in glycine release into the systemic circulation from the kidney compared with the sham group. This increase was attenuated in both the blood and brain of the OP-treated animals (P < 0.001 and P < 0.05, respectively), and the attenuation was associated with renal removal of glycine through excretion of the conjugation product phenylacetylglycine in urine (ALF + vehicle: 1,060 ± 106 μmol/l; ALF + OP: 27,625 ± 2,670 μmol/l; P < 0.003). Data from this study provide solid evidence for the existence of a novel, additional pathway for ammonia removal in ALF, involving glycine production and removal, which is targeted by OP.
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Affiliation(s)
- Rune Gangsøy Kristiansen
- Department of Anesthesiology, University Hospital of North Norway and UiT The Arctic University of Norway, Tromsø, Norway;
| | - Christopher F Rose
- Hepato-Neuro Laboratory, The University of Montreal Hospital Research Centre, Université de Montréal, Québec, Canada
| | - Ole-Martin Fuskevåg
- Department of Clinical Pharmacology, University Hospital of North Norway and UiT The Arctic University of Norway, Tromsø, Norway
| | - Hanne Mæhre
- Norwegian College of Fishery Science, UiT The Arctic University of Norway, Tromsø, Norway
| | - Arthur Revhaug
- Department of Digestive Surgery, University Hospital of North Norway and UiT The Arctic University of Norway, Tromsø, Norway; and
| | - Rajiv Jalan
- Liver Failure Group, University College London Institute for Liver and Digestive Health, Medical School, Royal Free Hospital, London, United Kingdom
| | - Lars Marius Ytrebø
- Department of Anesthesiology, University Hospital of North Norway and UiT The Arctic University of Norway, Tromsø, Norway
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Abstract
Human adults produce around 1000 mmol of ammonia daily. Some is reutilized in biosynthesis. The remainder is waste and neurotoxic. Eventually most is excreted in urine as urea, together with ammonia used as a buffer. In extrahepatic tissues, ammonia is incorporated into nontoxic glutamine and released into blood. Large amounts are metabolized by the kidneys and small intestine. In the intestine, this yields ammonia, which is sequestered in portal blood and transported to the liver for ureagenesis, and citrulline, which is converted to arginine by the kidneys. The amazing developments in NMR imaging and spectroscopy and molecular biology have confirmed concepts derived from early studies in animals and cell cultures. The processes involved are exquisitely tuned. When they are faulty, ammonia accumulates. Severe acute hyperammonemia causes a rapidly progressive, often fatal, encephalopathy with brain edema. Chronic milder hyperammonemia causes a neuropsychiatric illness. Survivors of severe neonatal hyperammonemia have structural brain damage. Proposed explanations for brain edema are an increase in astrocyte osmolality, generally attributed to glutamine accumulation, and cytotoxic oxidative/nitrosative damage. However, ammonia neurotoxicity is multifactorial, with disturbances also in neurotransmitters, energy production, anaplerosis, cerebral blood flow, potassium, and sodium. Around 90% of hyperammonemic patients have liver disease. Inherited defects are rare. They are being recognized increasingly in adults. Deficiencies of urea cycle enzymes, citrin, and pyruvate carboxylase demonstrate the roles of isolated pathways in ammonia metabolism. Phenylbutyrate is used routinely to treat inherited urea cycle disorders, and its use for hepatic encephalopathy is under investigation.
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Affiliation(s)
- Valerie Walker
- Department of Clinical Biochemistry, University Hospital Southampton NHS Foundation Trust, Southampton, United Kingdom.
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Hadjihambi A, Rose CF, Jalan R. Novel insights into ammonia-mediated neurotoxicity pointing to potential new therapeutic strategies. Hepatology 2014; 60:1101-3. [PMID: 24975882 DOI: 10.1002/hep.27282] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/06/2014] [Accepted: 06/25/2014] [Indexed: 01/31/2023]
Affiliation(s)
- Anna Hadjihambi
- Liver failure Group, Institute for Liver and Digestive Health, UCL Medical School, Royal Free Hospital, London, UK
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Jover-Cobos M, Noiret L, Lee K, Sharma V, Habtesion A, Romero-Gomez M, Davies N, Jalan R. Ornithine phenylacetate targets alterations in the expression and activity of glutamine synthase and glutaminase to reduce ammonia levels in bile duct ligated rats. J Hepatol 2014; 60:545-53. [PMID: 24512823 DOI: 10.1016/j.jhep.2013.10.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2013] [Revised: 10/07/2013] [Accepted: 10/08/2013] [Indexed: 12/21/2022]
Abstract
BACKGROUND & AIMS In liver failure, ammonia homeostasis is dependent upon the function of the ammonia metabolising enzymes, glutamine synthetase (GS) and glutaminase (GA) but data about their protein expression and activity are lacking. The aims of this study were to determine the protein expression and activity of GS and GA in individual organs in a rat model of chronic liver disease and to test whether the treatment with the ammonia-lowering agent ornithine phenylacetate (OP) modulates their activities. METHODS 49 SD rats were studied 35 days after sham-operation or bile duct ligation (BDL). The BDL group received: L-ornithine (0.6 mg/kg/day), Phenylacetate (0.6 mg/kg/day), OP (0.6 mg/kg/day) or placebo (saline) for 5 days prior to sacrifice. Arterial ammonia, amino acids and liver biochemistry were measured. Expressions of GS and GA were determined by Western-blotting and activities by end-point methods in liver, muscle, gut, kidney, lung, and frontal cortex. RESULTS In BDL rats, hepatic GS enzyme activity was reduced by more than 80% compared to sham rats. Further, in BDL rats GA activity was reduced in liver but increased in the gut, muscle and frontal cortex compared to sham rats. OP treatment resulted in a reduction in hyperammonemia in BDL rats, associated with increased GS activity in the muscle and reduced gut GA activity. CONCLUSIONS In a rat model of chronic liver failure, hyperammonemia is associated with inadequate compensation by liver and muscle GS activity and increased gut GA activity. OP reduces plasma ammonia by increasing GS in the muscle and reducing GA activity in the gut providing additional insights into its mechanism of its action. GS and GA may serve as important future therapeutic targets for hyperammonemia in liver failure.
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Affiliation(s)
- M Jover-Cobos
- Liver Failure Group, UCL Institute for Liver and Digestive Health, Royal Free Hospital Campus, University College of London (UCL), Pond Street, London, United Kingdom
| | - L Noiret
- Liver Failure Group, UCL Institute for Liver and Digestive Health, Royal Free Hospital Campus, University College of London (UCL), Pond Street, London, United Kingdom; COMPLEX CoMPLEX, UCL, Gower Street, London WC1E 6BT, United Kingdom
| | - K Lee
- Royal Veterinary College, Hatfield, Hertfordshire AL9 7TA, United Kingdom
| | - V Sharma
- Liver Failure Group, UCL Institute for Liver and Digestive Health, Royal Free Hospital Campus, University College of London (UCL), Pond Street, London, United Kingdom
| | - A Habtesion
- Liver Failure Group, UCL Institute for Liver and Digestive Health, Royal Free Hospital Campus, University College of London (UCL), Pond Street, London, United Kingdom
| | - M Romero-Gomez
- CIBEREHD, UCM Digestive Diseases, Valme University Hospital, Seville, Spain
| | - N Davies
- Liver Failure Group, UCL Institute for Liver and Digestive Health, Royal Free Hospital Campus, University College of London (UCL), Pond Street, London, United Kingdom
| | - R Jalan
- Liver Failure Group, UCL Institute for Liver and Digestive Health, Royal Free Hospital Campus, University College of London (UCL), Pond Street, London, United Kingdom.
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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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Blocking NMDA receptors delays death in rats with acute liver failure by dual protective mechanisms in kidney and brain. Neuromolecular Med 2013; 16:360-75. [PMID: 24338618 DOI: 10.1007/s12017-013-8283-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 12/03/2013] [Indexed: 01/06/2023]
Abstract
Treatment of patients with acute liver failure (ALF) is unsatisfactory and mortality remains unacceptably high. Blocking NMDA receptors delays or prevents death of rats with ALF. The underlying mechanisms remain unclear. Clarifying these mechanisms will help to design more efficient treatments to increase patient's survival. The aim of this work was to shed light on the mechanisms by which blocking NMDA receptors delays rat's death in ALF. ALF was induced by galactosamine injection. NMDA receptors were blocked by continuous MK-801 administration. Edema and cerebral blood flow were assessed by magnetic resonance. The time course of ammonia levels in brain, muscle, blood, and urine; of glutamine, lactate, and water content in brain; of glomerular filtration rate and kidney damage; and of hepatic encephalopathy (HE) and intracranial pressure was assessed. ALF reduces kidney glomerular filtration rate (GFR) as reflected by reduced inulin clearance. GFR reduction is due to both reduced renal perfusion and kidney tubular damage as reflected by increased Kim-1 in urine and histological analysis. Blocking NMDA receptors delays kidney damage, allowing transient increased GFR and ammonia elimination which delays hyperammonemia and associated changes in brain. Blocking NMDA receptors does not prevent cerebral edema or blood-brain barrier permeability but reduces or prevents changes in cerebral blood flow and brain lactate. The data show that dual protective effects of MK-801 in kidney and brain delay cerebral alterations, HE, intracranial pressure increase and death. NMDA receptors antagonists may increase survival of patients with ALF by providing additional time for liver transplantation or regeneration.
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Jover-Cobos M, Noiret L, Sharifi Y, Jalan R. Ornithine phenylacetate revisited. Metab Brain Dis 2013; 28:327-31. [PMID: 23456516 DOI: 10.1007/s11011-013-9391-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Accepted: 02/19/2013] [Indexed: 12/12/2022]
Abstract
In patients with liver failure hyperammonemia is associated with the development of hepatic encephalopathy (HE) and immune impairment. Treatment of hyperammonemia is an unmet clinical need. Ornithine phenylacetate (OP) is a novel drug that is targeted at reducing ammonia concentration in patients with liver disease and therefore a potential treatment for HE. This review describes the mechanism of action of OP and its effect on plasma ammonia levels, brain function and inflammation of OP in both acute and chronic liver failure. Ammonia levels could shown to be reduced for up to 24 h in animal models until 120 h in patients with repeated dosing of the drug. Reduction of plasma ammonia levels is due to the stimulation of ammonia removal in the form of glutamine (through glutamine synthetase), the direct excretion of ammonia in the form phenylacetylglutamine and to a normalisation of glutaminase activity in the gut. Administration of OP is associated with a reduction of brain oedema in rats with chronic bile duct ligation and diminution of intracranial hypertension in a pig model of ALF. Studies to date have indicated that it is safe in humans and trials in overt HE are underway to establish OP as a treatment for this major complication of liver disease.
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Affiliation(s)
- Maria Jover-Cobos
- Liver Failure Group, UCL Institute for Liver and Digestive Health, The Royal Free Hospital, University College London, Pond Street, London NW3 2PF, UK.
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Bosoi CR, Rose CF. Brain edema in acute liver failure and chronic liver disease: similarities and differences. Neurochem Int 2013; 62:446-57. [PMID: 23376027 DOI: 10.1016/j.neuint.2013.01.015] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 01/11/2013] [Accepted: 01/16/2013] [Indexed: 12/12/2022]
Abstract
Hepatic encephalopathy (HE) is a complex neuropsychiatric syndrome that typically develops as a result of acute liver failure or chronic liver disease. Brain edema is a common feature associated with HE. In acute liver failure, brain edema contributes to an increase in intracranial pressure, which can fatally lead to brain stem herniation. In chronic liver disease, intracranial hypertension is rarely observed, even though brain edema may be present. This discrepancy in the development of intracranial hypertension in acute liver failure versus chronic liver disease suggests that brain edema plays a different role in relation to the onset of HE. Furthermore, the pathophysiological mechanisms involved in the development of brain edema in acute liver failure and chronic liver disease are dissimilar. This review explores the types of brain edema, the cells, and pathogenic factors involved in its development, while emphasizing the differences in acute liver failure versus chronic liver disease. The implications of brain edema developing as a neuropathological consequence of HE, or as a cause of HE, are also discussed.
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Affiliation(s)
- Cristina R Bosoi
- Neuroscience Research Unit, Hôpital Saint-Luc (CRCHUM), Université de Montréal, Québec, Canada
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47
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Interorgan metabolism of ornithine phenylacetate (OP)—A novel strategy for treatment of hyperammonemia. Biochem Pharmacol 2013; 85:115-23. [DOI: 10.1016/j.bcp.2012.10.015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2012] [Revised: 10/15/2012] [Accepted: 10/16/2012] [Indexed: 11/24/2022]
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Bajaj JS, Ahluwalia V, Wade JB, Sanyal AJ, White MB, Noble NA, Monteith P, Fuchs M, Sterling RK, Luketic V, Bouneva I, Stravitz RT, Puri P, Kraft KA, Gilles H, Heuman DM. Asymmetric dimethylarginine is strongly associated with cognitive dysfunction and brain MR spectroscopic abnormalities in cirrhosis. J Hepatol 2013; 58:38-44. [PMID: 22889958 PMCID: PMC3508094 DOI: 10.1016/j.jhep.2012.08.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 07/30/2012] [Accepted: 08/02/2012] [Indexed: 01/11/2023]
Abstract
BACKGROUND & AIMS Asymmetric dimethylarginine (ADMA) is an inhibitor of nitric oxide synthase that accumulates in liver disease and may contribute to hepatic encephalopathy (HE). We aimed at evaluating the association of ADMA with cognition and brain MR spectroscopy (MRS) in cirrhosis. METHODS Cirrhotic patients with/without prior HE and non-cirrhotic controls underwent cognitive testing and ADMA determination. A subgroup underwent brain MRS [glutamine/glutamate (Glx), myoinositol (mI), N-acetyl-aspartate (NAA) in parietal white, occipital gray, and anterior cingulated (ACC)]. Cognition and ADMA in a cirrhotic subgroup before and one month after transjugular intrahepatic portosystemic shunting (TIPS) were also tested. Cognition and MRS values were correlated with ADMA and compared between groups using multivariable regression. ADMA levels were compared between those who did/did not develop post-TIPS HE. RESULTS Ninety cirrhotics (MELD 13, 54 prior HE) and 16 controls were included. Controls had better cognition and lower ADMA, Glx, and higher mI compared to cirrhotics. Prior HE patients had worse cognition, higher ADMA and Glx and lower mI compared to non-HE cirrhotics. ADMA was positively correlated with MELD (r=0.58, p<0.0001), abnormal cognitive test number (r=0.66, p<0.0001), and Glx and NAAA (white matter, ACC) and negatively with mI. On regression, ADMA predicted number of abnormal tests and mean Z-score independent of prior HE and MELD. Twelve patients underwent TIPS; 7 developed HE post-TIPS. ADMA increased post-TIPS in patients who developed HE (p=0.019) but not in others (p=0.89). CONCLUSIONS A strong association of ADMA with cognition and prior HE was found independent of the MELD score in cirrhosis.
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Affiliation(s)
- Jasmohan S Bajaj
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, VA 23249, USA.
| | - Vishwadeep Ahluwalia
- Radiology, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - James B Wade
- Psychology, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - Arun J Sanyal
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - Melanie B White
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - Nicole A Noble
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - Pamela Monteith
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - Michael Fuchs
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - Richard K Sterling
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - Velimir Luketic
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - Iliana Bouneva
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - Richard T Stravitz
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - Puneet Puri
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - Kenneth A Kraft
- Radiology, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - HoChong Gilles
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
| | - Douglas M Heuman
- Division of Gastroenterology, Hepatology and Nutrition, Virginia Commonwealth University and McGuire VA Medical Center, Richmond, Virginia
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Abstract
Acute hepatic failure (AHF) is a devastating clinical syndrome characterized by rapid impairment of liver functions and development of encephalopathy, multiple organ failure, and in most cases cerebral edema. AHF has a high mortality rate. Although advances in drug treatment, artificial liver and liver transplantation have significantly improved the prognosis of AHF, there is still a lack of effective treatment for AHF because of its complicated etiopathogenesis, rapid progression and less clinical knowledge about managing the disease. There is an urgent need to develop effective treatments for AHF. This article aims to review recent advances in the treatment of AHF.
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Bao J, Fisher JE, Lillegard JB, Wang W, Amiot B, Yu Y, Dietz AB, Nahmias Y, Nyberg SL. Serum-free medium and mesenchymal stromal cells enhance functionality and stabilize integrity of rat hepatocyte spheroids. Cell Transplant 2012; 22:299-308. [PMID: 23006214 DOI: 10.3727/096368912x656054] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Long-term culture of hepatocyte spheroids with high ammonia clearance is valuable for therapeutic applications, especially the bioartificial liver. However, the optimal conditions are not well studied. We hypothesized that liver urea cycle enzymes can be induced by high protein diet and maintain on a higher expression level in rat hepatocyte spheroids by serum-free medium (SFM) culture and coculture with mesenchymal stromal cells (MSCs). Rats were feed normal protein diet (NPD) or high protein diet (HPD) for 7 days before liver digestion and isolation of hepatocytes. Hepatocyte spheroids were formed and maintained in a rocked suspension culture with or without MSCs in SFM or 10% serum-containing medium (SCM). Spheroid viability, kinetics of spheroid formation, hepatic functions, gene expression, and biochemical activities of rat hepatocyte spheroids were tested over 14 days of culture. We observed that urea cycle enzymes of hepatocyte spheroids can be induced by high protein diet. SFM and MSCs enhanced ammonia clearance and ureagenesis and stabilized integrity of hepatocyte spheroids compared to control conditions over 14 days. Hepatocytes from high protein diet-fed rats formed spheroids and maintained a high level of ammonia detoxification for over 14 days in a novel SFM. Hepatic functionality and spheroid integrity were further stabilized by coculture of hepatocytes with MSCs in the spheroid microenvironment. These findings have direct application to development of the spheroid reservoir bioartificial liver.
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Affiliation(s)
- Ji Bao
- Department of Pathology, West China Hospital, Chengdu, Sichuan, People's Republic of China
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