Current approaches to hepatic encephalopathy

Treatment with hydrogen-rich water protects against thioacetamide-induced hepatic encephalopathy in rats through stabilizing liver-brain disturbance

Hepatic encephalopathy (HE), a neuropsychiatric complication secondary to liver cirrhosis and hepatic failure, represents the leading cause of mortality in end-stage liver disease. While hyperammonemia remains the central pathogenic factor in HE progression, emerging evidence implicates oxidative stress, neuroinflammation, and neuronal apoptosis as critical synergistic contributors to HE pathogenesis. Hydrogen-rich water, known for its antioxidant, anti-inflammatory, and anti-apoptotic properties, has not been systematically investigated for therapeutic efficacy in HE management. In the current investigation, we successfully established a HE rat model by administering thioacetamide via intraperitoneal injection. By observing the general state and behavioral changes of the rats, detecting liver function and blood ammonia, and observing the pathological changes of liver and brain tissue, it was discussed whether hydrogen-rich water had a preventive and therapeutic effect on hepatic encephalopathy. Oxidative stress, inflammation and neuronal apoptosis were detected in plasma, prefrontal cortex and hippocampus to explore the possible mechanism of its protective effect. The results showed that hydrogen-rich water can improve the behavioral changes of the HE rats, reduce blood ammonia, reduce liver function damage, alleviate the pathological changes of liver and brain tissue, significantly inhibit the systemic and local oxidative stress and inflammation of the brain tissue of the HE rats, and reduce neuronal apoptosis. In summary, hydrogen-rich water might stabilize liver-brain disturbance in thioacetamide-induced HE rats by anti-inflammation, anti-oxidative stress and reducing neuronal apoptosis.

Prevalence of hepatic encephalopathy in non-cirrhotic portal hypertension: A systematic review and meta-analysis

INTRODUCTION AND OBJECTIVES

The prevalence of hepatic encephalopathy (HE) in non-cirrhotic portal hypertension (NCPH) is not well established, despite evidence of its occurrence in both minimal (MHE) and overt forms (OHE). Accurate diagnosis and management of HE can reduce morbidity and improve patients' and their families' quality of life. This study aimed to systematically review the prevalence of HE in NCPH.

MATERIALS AND METHODS

Systematic research in five databases (MEDLINE, LILACS, MEDRXIV, SCIELO and Scopus) was carried out from January to April 2024 to detect studies that address the prevalence of MHE and OHE in patients with NCPH, using the terms: "Hepatic Encephalopathy" or "Psychometrics" or "Cognition Disorders" or "Cognition" and "Noncirrhotic Portal Hypertension".

RESULTS

Twelve studies were included, including 575 patients. The prevalence of HE in patients with NCPH is 12 % (95 % CI: 6-24; I2 83 %, p<0.01), with high heterogeneity, with the pooled prevalence in studies evaluating MHE being 21 % (95 % CI: 11-38; I2 73 %, p<0.01) and the prevalence of OHE being 4 % (95 %CI: 1-15; I2 83 %, p<0.01). The prevalence of HE by etiology of NCPH is as follows: EHPVO is 25 % (95 %CI: 11-45; I2 0 %; p=1), PVT 2 % (95 %CI: 0-15; I2 0 %, p=1), in PSVD 8 % (95 %CI: 5-14; I2 87 %; p<0.01) and idiopathic NCPH 9 % (95 %CI: 5-14; I2 68 %, p<0.01), with the last two analyzes showing high heterogeneity.

CONCLUSIONS

HE occurs in approximately 12 % of patients with NCPH, with MHE being more common than OHE. Etiology plays a significant role in HE prevalence.

Hepatic encephalopathy post-TIPS: Current status and prospects in predictive assessment

Transjugular intrahepatic portosystemic shunt (TIPS) is an essential procedure for the treatment of portal hypertension but can result in hepatic encephalopathy (HE), a serious complication that worsens patient outcomes. Investigating predictors of HE after TIPS is essential to improve prognosis. This review analyzes risk factors and compares predictive models, weighing traditional scores such as Child-Pugh, Model for End-Stage Liver Disease (MELD), and albumin-bilirubin (ALBI) against emerging artificial intelligence (AI) techniques. While traditional scores provide initial insights into HE risk, they have limitations in dealing with clinical complexity. Advances in machine learning (ML), particularly when integrated with imaging and clinical data, offer refined assessments. These innovations suggest the potential for AI to significantly improve the prediction of post-TIPS HE. The study provides clinicians with a comprehensive overview of current prediction methods, while advocating for the integration of AI to increase the accuracy of post-TIPS HE assessments. By harnessing the power of AI, clinicians can better manage the risks associated with TIPS and tailor interventions to individual patient needs. Future research should therefore prioritize the development of advanced AI frameworks that can assimilate diverse data streams to support clinical decision-making. The goal is not only to more accurately predict HE, but also to improve overall patient care and quality of life.

Ammonium chloride reduces excitatory synaptic transmission onto CA1 pyramidal neurons of mouse organotypic slice cultures

Acute liver dysfunction commonly leads to rapid increases in ammonia concentrations in both the serum and the cerebrospinal fluid. These elevations primarily affect brain astrocytes, causing modifications in their structure and function. However, its impact on neurons is not yet fully understood. In this study, we investigated the impact of elevated ammonium chloride levels (NH4Cl, 5 mM) on synaptic transmission onto CA1 pyramidal neurons in mouse organotypic entorhino-hippocampal tissue cultures. We found that acute exposure to NH4Cl reversibly reduced excitatory synaptic transmission and affected CA3-CA1 synapses. Notably, NH4Cl modified astrocytic, but not CA1 pyramidal neuron, passive intrinsic properties. To further explore the role of astrocytes in NH4Cl-induced attenuation of synaptic transmission, we used methionine sulfoximine to target glutamine synthetase, a key astrocytic enzyme for ammonia clearance in the central nervous system. Inhibition of glutamine synthetase effectively prevented the downregulation of excitatory synaptic activity, underscoring the significant role of astrocytes in adjusting excitatory synapses during acute ammonia elevation.

Understanding the role of the human gut microbiome in overweight and obesity

The gut microbiome may be related to the prevalence of overweight and obesity, but high interindividual variability of the human microbiome complicates our understanding. Obesity often occurs concomitantly with micronutrient deficiencies that impair energy metabolism. Microbiota composition is affected by diet. Host-microbiota interactions are bidirectional. We propose three pathways whereby these interactions may modulate the gut microbiome and obesity: (1) ingested compounds or derivatives affecting small intestinal transit, endogenous secretions, digestion, absorption, microbiome balance, and gut barrier function directly affect host metabolism; (2) substrate availability affecting colonic microbial composition and contact with the gut barrier; and (3) microbial end products affecting host metabolism. The quantity/concentration, duration, and/or frequency (circadian rhythm) of changes in these pathways can alter the gut microbiome, disrupt the gut barrier, alter host immunity, and increase the risk of and progression to overweight and obesity. Host-specific characteristics (e.g., genetic variations) may further affect individual sensitivity and/or resilience to diet- and microbiome-associated perturbations in the colonic environment. In this narrative review, the effects of selected interventions, including fecal microbiota transplantation, dietary calorie restriction, dietary fibers and prebiotics, probiotics and synbiotics, vitamins, minerals, and fatty acids, on the gut microbiome, body weight, and/or adiposity are summarized to help identify mechanisms of action and research opportunities.

Possible pathogenetic role of ammonia in liver cirrhosis without hyperammonemia of venous blood: The so-called latency period of abnormal ammonia metabolism

Ammonia plays a crucial role in the pathogenesis of hepatic encephalopathy. Ammonia is also involved in many other pathological conditions seen in cirrhosis, such as sarcopenia, liver fibrosis, hepatocellular injury, immune dysfunction, and hyperammonemia. Furthermore, the ammonia level of the veins is a useful prognostic factor for cirrhosis. In cirrhosis without hyperammonemia of the vein, however, covert hepatic encephalopathy has been reported. This discrepancy is because of the anatomical features of ammonia metabolism. There are two systems in the body for detoxifying ammonia: one is the urea cycle in the liver, and the other is the glutamine synthesis pathway in skeletal muscle and other tissues. The blood processed in the liver's urea cycle is then transported via arteries to various organs. Further processing occurs in the brain and skeletal muscle's glutamine synthesis pathway before entering the veins. When the urea cycle function decreases in cirrhosis, the ammonia levels in the artery increase. In response, the glutamine synthesis pathway compensates by increasing the capacity to process ammonia. Therefore, the ammonia concentration in the veins downstream of skeletal muscles does not increase immediately. However, the brain and skeletal muscles, which receive arterial blood, might be exposed to high ammonia concentrations. In addition, branched-chain amino acids in venous blood decrease. This period is the transition phase from early- to late-phase cirrhosis, and understanding the pathophysiology during this stage is extremely important for preventing the progression of cirrhosis.

[Effect of low-intensity laser-therapy in the correction of encephalopathy in obstructive jaundice]

Hepatic encephalopathy is an early and severe complication of obstructive jaundice and is characterized by occurrence of non-focal and focal neurological manifestations. Different methods of therapy are applied for disorder correction. Low-intensity laser blood irradiation has a pronounced antioxidant and vasoactive effect.

OBJECTIVE

To analyze the results of pharmaceutical treatment and low-intensity laser therapy use in encephalopathy correction in obstructive jaundice of non-neoplastic origin.

MATERIAL AND METHODS

The study was performed at the surgery department in the S.V. Katkov Republican Clinical Hospital (Saransk). The trial included 54 patients with moderate obstructive jaundice of non-neoplastic origin with latent encephalopathy, who were divided into 2 groups: the 1st group (control) consisted of 27 patients receiving standard pharmaceutical treatment; the 2nd group (study) - 27 patients receiving standard treatment and laser therapy (low-intensity laser irradiation in red emission at the cubital vein projection for 15 minutes). A comparative group (norm) included 20 healthy volunteers. All patients underwent biochemical studies (alanine aminotransferase and total bilirubin levels in the blood were assessed) after treatment. Registration of microcirculatory disorders and psychometric testing were conducted to reveal latent hepatic encephalopathy along with the evaluation of liver functional condition.

RESULTS

Correlation analysis showed the association of psychoneurological status improvement with liver functional condition (indicators of microcirculation and biochemical blood analysis were considered) in patients receiving a comprehensive therapy with laser irradiation. Correlation coefficient amounted to 0.87-0.96 (p<0.05).

CONCLUSION

The use of above vascular laser blood irradiation in a comprehensive treatment of moderate obstructive jaundice leads to improvement of liver functional condition (the first barrier organ on the toxin pathway) and to a significant reduction of latent encephalopathy's manifestations. The conducted treatment resulted in a reduction of initially elevated levels of alanine aminotransferase and total bilirubin. Laser therapy has an ability to restore microcirculation that leads to the improvement of psychoneurological status in patients with moderate obstructive jaundice.

The Mechanism of Hepatic Encephalopathy Induced by Thioacetamide Based on Metabolomics and Proteomics: A Preliminary Study

Hepatic encephalopathy (HE) is a central nervous system dysfunction syndrome caused by acute and chronic liver failure or various portal systemic shunt disorders. HE arises from metabolic disorder and excludes other known types of encephalopathy. HE is a major cause of death in people with liver disease. Early diagnosis and timely treatment are key to improving HE prognosis. Herein, we established a model of HE and performed metabolomics to identify 50 significantly differential metabolites between the HE group and control group. The main metabolic pathways associated with these differential metabolites were the purine metabolism, pyrimidine metabolism, aminoacyl tRNA biosynthesis, and glucose metabolism. Through proteomics analysis, we identified 226 significantly differential proteins (52 up-regulated and 174 down-regulated). The main (Kyoto Encyclopedia of Genes and Genomes) enrichment pathways were the Staphylococcus aureus infection, vitamin digestion and absorption, and complement and coagulation cascades. Through the conjoint analysis of proteomics and metabolomics, the differentially present proteins and metabolites were found to be involved in vitamin digestion and absorption, and ferroptosis pathways. In HE, malondialdehyde was significantly elevated, but glutathione was significantly diminished, and the redox balance was destroyed, thus leading to changes in proteins' levels associated with the ferroptosis pathway. In conclusion, this study preliminarily explored the molecular and metabolic mechanisms underlying HE.

A Comprehensive Overview of the Past, Current, and Future Randomized Controlled Trials in Hepatic Encephalopathy

Background: Hepatic encephalopathy (HE) caused by cirrhosis has severe consequences on an individual's lifespan, leading to long-term liver complications and potentially life-threatening outcomes. Despite recent interest in this condition, the effectiveness of secondary prophylaxis involving rixafimin, lactulose, or L-ornithine L-aspartate (LOLA) may be hindered by the unique microbial profiles each patient possesses. Methods: Thus, in this manuscript, we aimed to search, identify, and gather all randomized controlled trials (RCTs) published between 2000-2023 (November) in four major academic databases such as PubMed, ISI Web of Science, Scopus, and ScienceDirect by using a controlled terminology and web strings that reunite six main keywords. We complementarily retrieved data on the ongoing RCTs. Results: Regardless of the relatively high number of results displayed (n = 75), 46.66% (n = 35) were initially deemed eligible after the first evaluation phase after removing duplicates, n = 40 (53.34%). At the second assessment stage, we eliminated 11.42% (n = 4) studies, of which n = 22 finally met the eligibility criteria to be included in the main body of the manuscript. In terms of RCTs, otherwise found in distinct stages of development, n = 3 target FMT and n = 1 probiotics. Conclusions: Although we benefit from the necessary information and technology to design novel strategies for microbiota, only probiotics and synbiotics have been extensively studied in the last decade compared to FMT.

Hepatic encephalopathy: investigational drugs in preclinical and early phase development

INTRODUCTION

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome, in patients with liver disease, which affects life quality and span. Current treatments are lactulose or rifaximin, acting on gut microbiota. Treatments aiming ammonia levels reduction have been tested with little success.

AREAS COVERED

Pre-clinical research shows that the process inducing HE involves sequentially: liver failure, altered microbiome, hyperammonemia, peripheral inflammation, changes in immunophenotype and extracellular vesicles and neuroinflammation, which alters neurotransmission impairing cognitive and motor function. HE may be reversed using drugs acting at any step: modulating microbiota with probiotics or fecal transplantation; reducing peripheral inflammation with anti-TNFα, autotaxin inhibitors or silymarin; reducing neuroinflammation with sulforaphane, p38 MAP kinase or phosphodiesteras 5 inhibitors, antagonists of sphingosine-1-phosphate receptor 2, enhancing meningeal lymphatic drainage or with extracellular vesicles from mesenchymal stem cells; reducing GABAergic neurotransmission with indomethacin or golexanolone.

EXPERT OPINION

A factor limiting the progress of HE treatment is the lack of translation of research advances into clinical trials. Only drugs acting on microbiota or ammonia reduction have been tested in patients. It is urgent to change the mentality on how to approach HE treatment to develop clinical trials to assess drugs acting on the immune system/peripheral inflammation, neuroinflammation or neurotransmission to improve HE.