Citrate pharmacokinetics in critically ill liver failure patients receiving CRRT.

Citrate has been proposed as anticoagulation of choice in continuous renal replacement therapy (CRRT). However, little is known about the pharmacokinetics (PK) and metabolism of citrate in liver failure patients who require CRRT with regional citrate anticoagulation (RCA). This prospective clinical PK study was conducted at King Chulalongkorn Memorial Hospital between July 2019 to April 2021, evaluating seven acute liver failure (ALF) and seven acute-on-chronic liver failure (ACLF) patients who received CRRT support utilizing RCA as an anticoagulant at a citrate dose of 3 mmol/L. For evaluation of the citrate PK, we delivered citrate for 120 min and then stopped for a further 120 min. Total body clearance of citrate was 152.5 ± 50.9 and 195.6 ± 174.3 mL/min in ALF and ACLF, respectively. The ionized calcium, ionized magnesium, and pH slightly decreased after starting citrate infusion and gradually increased to baseline after stopping citrate infusion. Two of the ACLF patients displayed citrate toxicity during citrate infusion, while, no ALF patient had citrate toxicity. In summary, citrate clearance was significantly decreased in critically ill ALF and ACLF patients receiving CRRT. Citrate use as an anticoagulation in these patients is of concern for the risk of citrate toxicity.

Esculetin Alleviates Acute Liver Failure following Lipopolysaccharide/D-Galactosamine in Male C57BL/6 Mice.

Background: Acute liver failure (ALF) is a fatal clinical situation that rapidly leads to the loss of normal liver function. Esculetin is a natural herbal compound used for the management of various diseases such as cardiovascular and renal disorders. In this study, we evaluated the protective effects of esculetin in a mouse model of ALF. Methods: This article is a report on an experimental study that was conducted at Iran University of Medical Sciences in 2019. Forty-eight male C57BL/6 mice were randomly divided into control, LPS/D-Gal, and LPS/D-Gal+Esculetin (40 mg/kg) groups (n=16 per group). ALF was induced with an intraperitoneal injection of lipopolysaccharide (LPS)/D-galactosamine (D-Gal).The LPS/D-Gal group received a mixture of LPS (50 µg/kg) and D-Gal (400 mg/kg). The LPS/D-Gal+Esculetin group received esculetin by gavage 24 hours and one hour before receiving LPS/D-Gal. Six hours after LPS/D-Gal injection, the mice were sacrificed. Liver injury markers, including alanine aminotransferase (ALT), aspartate transaminase (AST), and alkaline phosphatase (ALP), were measured in the serum. Oxidative stress indices and inflammatory markers such as interleukin-1 beta (IL-1ß), IL-6, and tumor necrosis factor-alpha (TNF-α) were measured in hepatic tissue. The histopathology of liver tissue was also assessed. The data were analyzed using one-way ANOVA, followed by the post hoc Tukey test. Results: Esculetin lowered oxidative stress and myeloperoxidase activity (P<0.001); reduced the serum levels of ALT (P=0.037), AST (P=0.032), and ALP (P=0.004); and decreased the hepatic levels of IL-1ß (P=0.002), IL-6 (P=0.004), toll-like receptor 4 (P<0.001), TNF-α (P=0.003), and nuclear factor-kappa B (P<0.001) as compared with LPS/D-Gal. Additionally, esculetin ameliorated hepatic tissue injury following LPS/D-Gal challenge. Conclusion: Esculetin can reduce liver injury through the mitigation of oxidative burden, inflammation, and neutrophil infiltration and also exerts hepatoprotective effects against ALF.

Acute liver failure masquerading an occult malignancy.

Acute liver failure (ALF) is a rare initial presentation of metastatic liver disease and is associated with high fatality. Our case report describes acute hepatic decompensation from an occult pancreatic malignancy. A 64-year-old man presented with abdominal distension for 2 weeks associated with decreased appetite and a weight loss of 13.6 kg, over the past 8 months. Significant admission labs were serum creatinine: 6.15 mg/dL, serum bilirubin: 27 mg/dL, aspartate aminotransferase (AST): 316 u/L, alanine aminotransferase (ALT): 198 u/L and serum alkaline phosphatase: 2121 u/L. He was admitted to the medical intensive care unit and was started on dialysis for acute renal failure. MRI of the abdomen showed multiple masses in the liver concerning for metastatic disease, cystic lesions in the pancreatic body and ascites. He underwent paracentesis and ascitic fluid analysis was positive for adenocarcinoma. CA 19-9 was 17 828 u/mL. The patient's condition gradually deteriorated, and he died of cardiac arrest.

Novel strategies for the treatment of acetaminophen hepatotoxicity.

INTRODUCTION: Acetaminophen (APAP) hepatotoxicity is the leading cause of acute liver failure in the western world. Despite extensive investigations into the mechanisms of cell death, only a single antidote, N-acetylcysteine, is in clinical use. However, there have recently been more efforts made to translate mechanistic insight into identification of therapeutic targets and potential new drugs for this indication. AREAS COVERED: After a short review of the key events in the pathophysiology of APAP-induced liver injury and recovery, the pros and cons of targeting individual steps in the pathophysiology as therapeutic targets are discussed. While the re-purposed drug fomepizole (4-methylpyrazole) and the new entity calmangafodipir are most advanced based on the understanding of their mechanism of action, several herbal medicine extracts and their individual components are also considered. EXPERT OPINION: Fomepizole (4-methylpyrazole) is safe and has shown efficacy in preclinical models, human hepatocytes and in volunteers against APAP overdose. The safety of calmangafodipir in APAP overdose patients was shown but it lacks solid preclinical efficacy studies. Both drugs require a controlled phase III trial to achieve regulatory approval. All studies of herbal medicine extracts and components suffer from poor experimental design, which questions their clinical utility at this point.

Falla hepática aguda en pediatría / Pediatric acute liver failure

Resumen: La falla hepática aguda (FHA) es poco frecuente en pediatría, amenaza la vida y requiere aborda je multidisciplinario para su diagnóstico y tratamiento tempranos. El presente artículo tiene como objetivo realizar actualización de definiciones, enfoques y tratamientos disponibles. Los artículos se obtuvieron de la revisión de la literatura disponible entre 2000 y 2020 en varias bases de datos (Pub- med, LILACS, BIREME, Google Académico y UpToDate), empleando términos "acute liver failure" en Pubmed, "pediatric acute liver failure", "falla hepática aguda en pediatría" para otros buscadores y aplicando filtros según edad, fecha de publicación y tipo de estudio (ensayos clínicos, artículos de revisión, revisiones sistemáticas, estudios de casos y controles), se eligieron aquellos artículos con mayor número de citaciones y con datos recientes. La FHA requiere soporte en cuidado intensivo pe diátrico y su diagnóstico temprano favorece la instauración del tratamiento. Se recomienda el enfo que de pruebas diagnósticas específicas por edad en pacientes pediátricos con FHA. No hay consenso acerca de las indicaciones de trasplante hepático en FHA en pediatría.

Abstract: Acute liver failure (ALF) is a rare and life-threatening entity in pediatrics which requires a multidis ciplinary approach for early diagnosis and treatment. The objective of this article is to update defi nitions, management, and available treatments. We obtained the articles by reviewing the literature available between 2000 and 2020 in different databases (Pubmed, LILACS, BIREME, Google Scholar, and UpToDate), using terms such as "acute liver failure" in Pubmed, and in other databases "pedia tric acute liver failure" and "falla hepática aguda en pediatría" using filters such as age, publication date, and types of study (clinical trials, review articles, systematic reviews, and case-control studies). We chose those articles with the highest number of citations and with recent data. The ALF requires support in the pediatric intensive care unit and its early diagnosis favors the beginning of treatment. In pediatric patients with ALF, it is recommended to focus on age-specific diagnostic testing. There is no agreement regarding the liver transplantation in pediatric cases of ALF.

Nifuroxazide attenuates experimentally-induced hepatic encephalopathy and the associated hyperammonemia and cJNK/caspase-8/TRAIL activation in rats.

Hyperammonemia is a serious metabolic disorder associating with hepatic encephalopathy (HE) which occurs secondary to several forms of liver injury ranging from simple acute liver failure (ALF) to its most serious form; cirrhosis. The resent study highlights the possible ameliorative effect of oral nifuroxazide (25 mg/kg) against experimentally induced ALF and the subsequent HE in a well-standardized rat model. ALF and HE were induced in a rat model by I.P. injection of thioacetamide (TAA) (200 mg/kg) for 1 week at alternative days. Nifuroxazide administration for 14 days prior to and for further 7 days alongside TAA injection successfully attenuated TAA-induced ALF and HE; as demonstrated by the significant retraction in both brain and serum hyperammonemia with significant improvement in liver function biomarkers; ALT, AST, ALP, GGT, albumin, and serum total protein. This was associated with a significant restoration of both hepatic and brain oxidative stress incidences; MDA, SOD and catalase activities and GSH concentration. The observed improvement was associated with a significant reduction in liver and brain contents of c-Jun N-terminal kinase (cJNK); as an anti-inflammatory biomarker and a modulator of various pro- and anti-apoptotic proteins, caspase-8, and tumor necrosis factor-related apoptosis ligand (TRAIL); as biomarkers of apoptosis. In conclusion; the modulatory effect of nifuroxazide on cJNK/caspase-8/TRAIL signaling appears to underly its hepatoprotective effect and its ameliorative effect on HE progression.

Therapeutic targets for liver regeneration after acute severe injury: a preclinical overview.

Introduction: Liver transplantation is the only viable treatment with a proven survival benefit for acute liver failure (ALF). Donor organ shortage is, however, a major hurdle; hence, alternative approaches that enable liver regeneration and target acute severe hepatocellular damage are necessary.Areas covered: This article sheds light on therapeutic targets for liver regeneration and considers their therapeutic potential. ALF following extensive hepatocyte damage and small-for-size syndrome (SFSS) are illuminated for the reader while the molecular mechanisms of liver regeneration are assessed in accordance with relevant therapeutic strategies. Furthermore, liver background parameters and predictive biomarkers that might associate with liver regeneration are reviewed.Expert opinion: There are established and novel experimental strategies for liver regeneration to prevent ALF resulting from SFSS. Granulocyte-colony stimulating factor (G-CSF) is a promising agent targeting liver regeneration after acute severe injury. Autophagy and hepatocyte senescence represent attractive new targets for liver regeneration in acute severe hepatic injury. Liver support strategies, including tissue engineering, constitute novel regenerative means; the success of this is dependent on stem cell research advances. However, there is no firm clinical evidence that these supportive strategies may alleviate hepatocellular damage until liver transplantation becomes available or successful self-liver regeneration occurs.

Bone marrow mesenchymal stem cell-derived exosomes attenuate D-GaIN/LPS-induced hepatocyte apoptosis by activating autophagy in vitro.

BACKGROUND: Acute liver failure is an inflammation-mediated hepatocyte injury. Mesenchymal stem cell (MSC) transplantation is currently considered to be an effective treatment strategy for acute liver failure. Exosomes are an important paracrine factor that can be used as a direct therapeutic agent. However, the use of bone marrow mesenchymal stem cell-derived exosomes (BMSC-Exos) in the treatment of acute liver failure has not been reported. PURPOSE: Here, we established a model of hepatocyte injury and apoptosis induced by D-galactosamine and lipopolysaccharide (D-GalN/LPS) to study the protective effect of BMSC-Exos on hepatocyte apoptosis, and further explored its protective mechanism. METHODS: BMSC-Exos was identified by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and Western blot. Laser confocal microscopy was used to observe the uptake of Dil-Exos by hepatocytes. D-GalN/LPS-induced primary hepatocytes were pretreated with BMSC-Exos in vitro, and then the cells were harvested. The apoptosis of hepatocytes was observed by TUNEL staining, flow cytometry and Western blot. Electron microscopy and mRFP-GFP-LC3 and Western blot was used to observe autophagy. RESULTS: BMSC-Exos increased the expression of autophagy marker proteins LC3 and Beclin-1 and promoted the formation of autophagosomes. After BMSC-Exos treatment, the expression levels of the proapoptotic proteins Bax and cleaved caspase-3 were significantly decreased, while the expression level of the anti-apoptotic protein Bcl-2 was upregulated. However, when the autophagy inhibitor 3MA was present, the effect of BMSC-Exos on inhibiting apoptosis was significantly reversed. CONCLUSIONS: Our results showed for the first time that BMSC-Exos had the potential to reduce hepatocyte apoptosis after acute liver failure. In particular, we found that BMSC-Exos attenuated hepatocyte apoptosis by promoting autophagy.

Cellular and functional loss of liver endothelial cells correlates with poor hepatocyte regeneration in acute-on-chronic liver failure.

BACKGROUND AND AIM: Acute hepatic insult triggers regeneration. If acute-on-chronic liver failure (ACLF) patients have a poorer regenerative response than acute liver failure (ALF) patients, and if so, the mechanisms underlying this, are not well understood. METHODS: We investigated the status of hepatocyte proliferation, hepatic progenitor cell (HPC) mediated regeneration, non-parenchymal cells (through immunohistochemistery), cytokines and growth factors (cytokine bead array) in liver and peripheral blood of ACLF (n = 29) and ALF (n = 17) patients. Liver endothelial cells, mesenchymal cells and Kupffer cells were isolated from explant livers and analysis of regenerative factors was done by qRT-PCR. RESULTS: Unlike ALF, the ACLF livers showed decreased hepatocyte proliferation (p < 0.001) and profound ductular-reaction with increased CK19 + hepatocytes (p < 0.0001). However, only decrease in Ki67+ hepatocytes was associated with 28 day mortality in ACLF (p < 0.001; HR = 0.78; 95% CI 0.69-0.88). In both groups, increase in plasma hepatocyte growth factor (HGF) (OR = 21.87 p = 0.002;), macrophage colony stimulating factor (MCSF) (OR = 21.73; p = 0.002) and stromal derived factor (SDF1)(OR = 10.2; p = 0.001) were associated with hepatocyte proliferation and decreased (> fivefolds) levels were associated with poor hepatocyte regeneration in ACLF patients. ACLF livers showed decrease in endothelial cells (p < 0.01) and expression of regenerative angiocrine factors C-X-C chemokine receptor type 7 (CXCR7), Inhibitor of DNA Binding 1(IDI) and HGF compared to ALF. In co-culture, while ALF liver mesenchymal stromal cells (LMSCs) induced the expression of CXCR7, IDI and HGF in human umbilical cord endothelial cells (HUVECs), the ACLF LMSCs were defective and showed decreased production of SDF-1, HGF and MCSF compared to ALF. CONCLUSIONS: Decrease in hepatic endothelial cells and their regenerative angiocrine functions indicated by defective CXCR7-ID1 dependent HGF expression underlie the poor hepatocyte proliferation in ACLF compared to ALF patients. A robust hepatocyte self-replication is lacking in the livers of ACLF patients and is associated with poor survival.

Transjugular Portosystemic Shunt Reductions: A Retrospective Single-Center Experience.

PURPOSE: To report the results of transjugular intrahepatic portosystemic shunt (TIPS) reductions for hepatic encephalopathy (HE), acute liver failure (ALF), and pulmonary hypertension (PH). MATERIALS AND METHODS: A single-institution retrospective review analysis was performed between 2007 and 2017 on patients undergoing TIPS reduction at single tertiary liver transplant center. A total of 27 patients (14 males and 13 females) underwent TIPS reduction for refractory HE (n = 18), ALF (n = 7), and PH (n = 2). The average age at time of reduction was 59 years (range, 23-73; standard deviation [SD], 8). Mean prereduction Model of End-State Liver Disease-Na and portosystemic pressure gradient were 19 (range, 11-29; SD, 6) and 9.4 mm Hg (range, -2 to 19; SD, 4.8), respectively. Comparison between responders and nonresponders was performed for multiple variables using a 2-tailed t test. Methods of reduction were compared in cases of HE. RESULTS: Technical success, defined as a decrease of at least 50% of the caliber of the shunt, was 100%. Clinical success rates in improving HE, ALF, and PH were calculated at 89%, 71%, and 100%, respectively. Eight patients had major and 10 had minor complications after the reductions. There were 3 shunt thrombosis. Pre- and postreduction Model of End-State Liver Disease-Na, portosystemic pressure gradient change, duration of indwelling TIPS, and reduction method were not significantly different between responders and nonresponders. Six-month survival rates were 80%, 20%, and 100% for HE, ALF, and PH, respectively. CONCLUSIONS: TIPS reduction is effective in reversing refractory HE, ALF, and PH after TIPS creation. TIPS reduction is associated with a high rate of complications and should be reserved for severe refractory overshunting complications.

Behavioral, Neurochemical and Brain Oscillation Abnormalities in an Experimental Model of Acute Liver Failure.

Hepatic encephalopathy (HE) represents a brain dysfunction caused by both acute and chronic liver failures, and its severity deeply affects the prognosis of patients with impaired liver function. In its pathophysiology, ammonia levels and glutamatergic system hyperactivity seem to play a pivotal role in the disruption of brain homeostasis. Here, we investigate important outcomes involved in behavioral performance, electroencephalographic patterns, and neurochemical parameters to better characterize the well-accepted animal model of acute liver failure (ALF) induced by subtotal hepatectomy (92% removal of tissue) that produces ALF. This study was divided into three cohorts: (1) rats clinically monitored after hepatectomy every 6 h for 96 h or until death; (2) rats tested in an open-field task (OFT) before and after surgery and had blood, cerebrospinal fluid, and brain tissue collected after the last OFT; and (3) rats that had continuous EEGs recorded before and after surgery for 3 days. The hepatectomized rats presented significant motor behavioral changes accompanied by important abnormalities in classical blood laboratory parameters of ALF, and EEG features suggestive of HE and deep disturbances in the brain glutamatergic system. Using an animal model of ALF induced via subtotal hepatectomy, this work provides a comprehensive and reliable experimental model that increases the opportunity for studying the effects of new treatment strategies to be explored in an unprecedented way. It also presents insights into the pathophysiology of HE in a reproducible model of ALF, which correlates important neurochemical and EEG aspects of the syndrome.

Acute Liver Failure: From Textbook to Emergency Room and Intensive Care Unit With Concomitant Established and Modern Novel Therapies.

Acute liver failure is a rare hepatic emergent situation that affects primarily young people and has often a catastrophic or even fatal outcome. Definition of acute liver failure has not reached a universal consensus and the interval between the appearance of jaundice and hepatic encephalopathy for the establishment of the acute failure is a matter of debate. Among the wide variety of causes, acetaminophen intoxication in western societies and viral hepatitis in the developing countries rank at the top of the etiology list. Identification of the clinical appearance and initial management for the stabilization of the patient are of vital significance. Further advanced therapies, that require intensive care unit, should be offered. The hallmark of treatment for selected patients can be orthotopic liver transplantation. Apart from well-established treatments, novel therapies like hepatocyte or stem cell transplantation, additional new therapeutic strategies targeting acetaminophen intoxication and/or hepatic encephalopathy are mainly experimental, and some of them do not belong, yet, to clinical practice. For clinicians, it is substantial to have the alertness to timely identify the patient and transfer them to a specialized center, where more treatment opportunities are available.

Mesenchymal Stem Cell/Red Blood Cell-Inspired Nanoparticle Therapy in Mice with Carbon Tetrachloride-Induced Acute Liver Failure.

Acute liver failure is a critical condition characterized by global hepatocyte death and often time needs a liver transplantation. Such treatment is largely limited by donor organ shortage. Stem cell therapy offers a promising option to patients with acute liver failure. Yet, therapeutic efficacy and feasibility are hindered by delivery route and storage instability of live cell products. We fabricated a nanoparticle that carries the beneficial regenerative factors from mesenchymal stem cells and further coated it with the membranes of red blood cells to increase blood stability. Unlike uncoated nanoparticles, these particles promote liver cell proliferation in vitro and have lower internalization by macrophage cells. After intravenous delivery, these artificial stem cell analogs are able to remain in the liver and mitigate carbon tetrachloride-induced liver failure in a mouse model, as gauged by histology and liver function test. Our technology provides an innovative and off-the-shelf strategy to treat liver failure.

Acute liver failure due to liver parenchymal infiltration with acute myelogenous leukaemia in a patient with myelodysplastic syndrome.

Liver involvement by acute leukaemia is rare and has a high mortality rate despite treatment. We report a case of a 66-year-old woman undergoing treatment for myelodysplastic syndrome with Vidaza (azacitidine) who presented with abnormal liver function tests. Despite negative serologic testing and unremarkable abdominal MRI, she continued to have significant elevation in bilirubin and international normalised ratio and worsening mental status. Liver biopsy was obtained and consistent with acute myelogenous leukaemia. The patient had rapid demise due to acute liver failure and was unable to undergo treatment.

Imatinib-induced fulminant liver failure in chronic myeloid leukemia: role of liver transplant and second-generation tyrosine kinase inhibitors: a case report.

BACKGROUND: There is a worldwide problem of acute liver failure and mortality associated with remaining on the waiting for a liver transplant. In this study, we highlight results published in recent years by leading transplant centers in evaluating imatinib-induced acute liver failure in chronic myeloid leukemia and follow-up in liver transplantation. CASE PRESENTATION: A 36-year-old brown-skinned woman (mixed Brazilian race) diagnosed 1 year earlier with chronic myeloid leukemia was started after delivery of a baby and continued for 6 months with imatinib mesylate (selective inhibitor of Bcr-Abl tyrosine kinase), which induced liver failure. We conducted a literature review using the PubMed database for articles published through September 2017, and we demonstrate a role of liver transplant in this situation for imatinib-induced liver failure. We report previously published results and a successful liver transplant after acute liver failure due to imatinib-induced in chronic myeloid leukemia treatment. CONCLUSIONS: We report a case of a successful liver transplant after acute liver failure resulting from imatinib-induced chronic myeloid leukemia treatment. The literature reveals the importance of prompt acute liver failure diagnosis and treatment with liver transplant in selected cases.

SOFA nas primeiras 24 horas como preditor de desfecho em insuficiência hepática aguda / SOFA in the first 24 hours as an outcome predictor of acute liver failure

RESUMO Objetivo: Descrever uma coorte de doentes com insuficiência hepática aguda, e analisar os fatores demográficos e clínicos associados à mortalidade. Métodos: Estudo de coorte retrospectivo em que todos os pacientes admitidos por insuficiência hepática aguda foram incluídos no período de 28 de julho de 2012 a 31 de agosto de 2017. Dados clínicos e demográficos foram coletados via Sistema Epimed. Foram mensurados SAPS 3, SOFA e MELD. Estimaram-se as OR e seus IC95%. Foram obtidas as curvas Características de Operação do Receptor para os escores de prognóstico, assim como a curva Kaplan-Meier de sobrevida para o escore com melhor predição de mortalidade. Resultados: A maioria dos 40 doentes era do sexo feminino (77,5%), e a etiologia mais frequente foi hepatite pelo vírus B (n = 13). Apenas 35% dos doentes foram submetidos ao transplante hepático. A mortalidade hospitalar foi de 57,5% (IC95%: 41,5 - 73,5). Dentre os escores investigados, apenas o SOFA se manteve associado ao risco de morte (OR = 1,37; IC95% 1,11 - 1,69; p < 0,001). Após a estratificação do SOFA em < 12 e ≥ 12 pontos, a sobrevida foi maior nos pacientes com SOFA < 12 (Log-rank p < 0,001). Conclusão: SOFA nas primeiras 24 horas foi o maior preditor de desfecho fatal.

ABSTRACT Objective: To describe a cohort of patients with acute liver failure and to analyze the demographic and clinical factors associated with mortality. Methods: Retrospective cohort study in which all patients admitted for acute liver failure from July 28, 2012, to August 31, 2017, were included. Clinical and demographic data were collected using the Epimed System. The SAPS 3, SOFA, and MELD scores were measured. The odds ratios and 95% confidence intervals were estimated. Receiver operating characteristics curves were obtained for the prognostic scores, along with the Kaplan-Meier survival curve for the score best predicting mortality. Results: The majority of the 40 patients were female (77.5%), and the most frequent etiology was hepatitis B (n = 13). Only 35% of the patients underwent liver transplantation. The in-hospital mortality rate was 57.5% (95%CI: 41.5 - 73.5). Among the scores investigated, only SOFA remained associated with risk of death (OR = 1.37; 95%CI 1.11 - 1.69; p < 0.001). After SOFA stratification into < 12 and ≥ 12 points, survival was higher in patients with SOFA <12 (log-rank p < 0.001). Conclusion: SOFA score in the first 24 hours was the best predictor of fatal outcome.

Impaired cerebral microcirculation induced by ammonium chloride in rats is due to cortical adenosine release.

BACKGROUND & AIMS: Liver failure results in hyperammonaemia, impaired regulation of cerebral microcirculation, encephalopathy, and death. However, the key mediator that alters cerebral microcirculation remains unidentified. In this study we show that topically applied ammonium significantly increases periarteriolar adenosine tone on the brain surface of healthy rats and is associated with a disturbed microcirculation. METHODS: Cranial windows were prepared in anaesthetized Wistar rats. The flow velocities were measured by speckle contrast imaging and compared before and after 30 min of exposure to 10 mM ammonium chloride applied on the brain surface. These flow velocities were compared with those for control groups exposed to artificial cerebrospinal fluid or ammonium plus an adenosine receptor antagonist. A flow preservation curve was obtained by analysis of flow responses to a haemorrhagic hypotensive challenge and during stepwise exsanguination. The periarteriolar adenosine concentration was measured with enzymatic biosensors inserted in the cortex. RESULTS: After ammonium exposure the arteriolar flow velocity increased by a median (interquartile range) of 21.7% (23.4%) vs. 7.2% (10.2%) in controls (n = 10 and n = 6, respectively, p <0.05), and the arteriolar surface area increased. There was a profound rise in the periarteriolar adenosine concentration. During the hypotensive challenge the flow decreased by 27.8% (14.9%) vs. 9.2% (14.9%) in controls (p <0.05). The lower limit of flow preservation remained unaffected, 27.7 (3.9) mmHg vs. 27.6 (6.4) mmHg, whereas the autoregulatory index increased, 0.29 (0.33) flow units per millimetre of mercury vs. 0.03 (0.21) flow units per millimetre of mercury (p <0.05). When ammonium exposure was combined with topical application of an adenosine receptor antagonist, the autoregulatory index was normalized. CONCLUSIONS: Vasodilation of the cerebral microcirculation during exposure to ammonium chloride is associated with an increase in the adenosine tone. Application of a specific adenosine receptor antagonist restores the regulation of the microcirculation. This indicates that adenosine could be a key mediator of the brain dysfunction seen during hyperammonaemia and is a potential therapeutic target. LAY SUMMARY: In patients with liver failure, disturbances in brain function are caused in part by ammonium toxicity. In our project we studied how ammonia, through adenosine release, affects the blood flow in the brain of rats. In our experimental model we demonstrated that the detrimental effect of ammonia on blood flow regulation was counteracted by blocking the adenosine receptors in the brain. With this observation we identified a novel potential treatment target. If we can confirm our findings in a future clinical study, this might help patients with liver failure and the severe condition called hepatic encephalopathy.

Interfering RNA against PKC-α inhibits TNF-α-induced IP3R1 expression and improves glomerular filtration rate in rats with fulminant hepatic failure.

We have reported that tumor necrosis factor-α (TNF-α) is critical for reduction of glomerular filtration rate (GFR) in rats with fulminant hepatic failure (FHF). The present study aims to evaluate the underlying mechanisms of decreased GFR during acute hepatic failure. Rats with FHF induced by d-galactosamine plus lipopolysaccharide (GalN/LPS) were injected intravenously with recombinant lentivirus harboring short hairpin RNA against the protein kinase C-α ( PKC-α) gene (Lenti-shRNA-PKC-α). GFR, serum levels of aminotransferases, creatinine, urea nitrogen, potassium, sodium, chloride, TNF-α, and endothelin-1 (ET-1), as well as type 1 inositol 1,4,5-trisphosphate receptor (IP3R1) expression in renal tissue were assessed. The effects of PKC-α silencing on TNF-α-induced IP3R1, specificity protein 1 (SP-1), and c-Jun NH2-terminal kinase (JNK) expression, as well as cytosolic calcium content were determined in glomerular mesangial cell (GMCs) with RNAi against PKC-α. Renal IP3R1 overexpression was abrogated by pre-treatment with Lenti-shRNA-PKC-α. The PKC-α silence significantly improved the compromised GFR, reduced Cr levels, and reversed the decrease in glomerular inulin space and the increase in glomerular calcium content in GalN/LPS-exposed rats. TNF-α treatment increased expression of PKC-α, IP3R1, specificity protein 1 (SP-1), JNK, and p-JNK in GMCs and increased Ca2 + release and binding activity of SP-1 to the IP3R1 promoter. These effects were blocked by transfection of siRNA against the PKC-α gene, and the PKC-α gene silence also restored cytosolic Ca2+ concentration. RNAi targeting PKC-α inhibited TNF-α-induced IP3R1 overexpression and in turn improved compromised GFR in the development of acute kidney injury during FHF in rats.