IL-6 and IL-18 in blood may discriminate cirrhotic patients with and without minimal hepatic encephalopathy

Role of peripheral inflammation in minimal hepatic encephalopathy

Many patients with liver cirrhosis show minimal hepatic encephalopathy (MHE) with mild cognitive impairment (MCI) and motor alterations that reduce their quality of life. Some patients with steatotic liver disease also suffer MCI. To design treatments to improve MHE/MCI it is necessary to understand the mechanisms by which liver disease induce them. This review summarizes studies showing that appearance of MHE/MCI is associated with a shift in the immunophenotype leading to an "autoimmune-like" form with increased pro-inflammatory monocytes, enhanced CD4 T and B lymphocytes activation and increased plasma levels of pro-inflammatory cytokines, including IL-17, IL-21, TNFα, IL-15 and CCL20. The contribution of peripheral inflammation to trigger MHE is supported by studies in animal models and by the fact that rifaximin treatment reverses MHE in around 60% of patients in parallel with reversal of the changes in peripheral inflammation. MHE does not improve in patients in which peripheral inflammation is not improved by rifaximin. The process by which peripheral inflammation induces MHE involves induction of neuroinflammation in brain, with activation of microglia and astrocytes and increased pro-inflammatory TNFα and IL-1β, which is observed in patients who died with steatotic liver disease (SLD) or liver cirrhosis and in animal models of MHE. Neuroinflammation alters glutamatergic and GABAergic neurotransmission, leading to cognitive and motor impairment. Transmission of peripheral alterations into the brain is mediated by infiltration in brain of extracellular vesicles from plasma and of cells from the peripheral immune system. Acting on any step of the process peripheral inflammation - neuroinflammation - altered neurotransmission may improve MHE.

Correlation of ammonia and blood laboratory parameters with hepatic encephalopathy: A systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Emerging research suggests that hyperammonemia may enhance the probability of hepatic encephalopathy (HE), a condition associated with elevated levels of circulating ammonia in patients with cirrhosis. However, some studies indicate that blood ammonia levels may not consistently correlate with the severity of HE, highlighting the complex pathophysiology of this condition.

METHODS

A systematic review and meta-analysis through PubMed, Scopus, Embase, Web of Science, and Virtual Health Library were conducted to address this complexity, analyzing and comparing published data on various laboratory parameters, including circulating ammonia, blood creatinine, albumin, sodium, and inflammation markers in cirrhotic patients, both with and without HE.

RESULTS

This comprehensive review, which included 81 studies from five reputable databases until June 2024, revealed a significant increase in circulating ammonia levels in cirrhotic patients with HE, particularly those with overt HE. Notably, significant alterations were observed in the circulating creatinine, albumin, sodium, interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNFα) in HE patients.

CONCLUSIONS

These findings suggest an association between ammonia and HE and underscore the importance of considering other blood parameters such as creatinine, albumin, sodium, and pro-inflammatory cytokines when devising new treatment strategies for HE.

Elevated serum neurofilament light chain levels are associated with hepatic encephalopathy in patients with cirrhosis

Increasing evidences implicate vital role of neuronal damage in the development of hepatic encephalopathy (HE). Neurofilament light chain (NfL) is the main frame component of neurons and is closely related to axonal radial growth and neuronal structural stability. We hypothesized that NfL as a biomarker of axonal injury may contribute to early diagnosis of HE. This study recruited 101 patients with liver cirrhosis, 10 healthy individuals, and 7 patients with Parkinson's disease. Minimal hepatic encephalopathy (MHE) was diagnosed using psychometric hepatic encephalopathy score. Serum NfL levels were measured by the electrochemiluminescence immunoassay. Serum NfL levels in cirrhotic patients with MHE were significantly higher than cirrhotic patients without MHE, and increased accordingly with the aggravation of HE. Serum NfL levels were associated with psychometric hepatic encephalopathy score, Child-Pugh score, model for end-stage liver disease score, and days of hospitalization. Additionally, serum NfL was an independent predictor of MHE (odds ratio of 1.020 (95% CI 1.005-1.034); P = 0.007). The discriminative abilities of serum NfL were high for identifying MHE (AUC of 0.8134 (95% CI 0.7130-0.9219); P ˂ 0.001) and OHE (AUC of 0.8852 (95% CI 0.8117-0.9587); P ˂ 0.001). Elevated serum NfL levels correlated with the presence of MHE and associated with the severity of HE, are expected to be a biomarker in patients with cirrhosis. Our study suggested that neuronal damage may play a critical role in the development of HE.

Allopregnanolone and its antagonist modulate neuroinflammation and neurological impairment

Neuroinflammation accompanies several brain disorders, either as a secondary consequence or as a primary cause and may contribute importantly to disease pathogenesis. Neurosteroids which act as Positive Steroid Allosteric GABA-A receptor Modulators (Steroid-PAM) appear to modulate neuroinflammation and their levels in the brain may vary because of increased or decreased local production or import from the systemic circulation. The increased synthesis of steroid-PAMs is possibly due to increased expression of the mitochondrial cholesterol transporting protein (TSPO) in neuroinflammatory tissue, and reduced production may be due to changes in the enzymatic activity. Microglia and astrocytes play an important role in neuroinflammation, and their production of inflammatory mediators can be both activated and inhibited by steroid-PAMs and GABA. What is surprising is the finding that both allopregnanolone, a steroid-PAM, and golexanolone, a novel GABA-A receptor modulating steroid antagonist (GAMSA), can inhibit microglia and astrocyte activation and normalize their function. This review focuses on the role of steroid-PAMs in neuroinflammation and their importance in new therapeutic approaches to CNS and liver disease.

Influence of NOD2 risk variants on hepatic encephalopathy and association with inflammation, bacterial translocation and immune activation

BACKGROUND

Nucleotide-binding oligomerization domain containing 2 (NOD2) risk variants lead to impaired mucosal barrier function, increased bacterial translocation (BT), and systemic inflammation.

AIM

To evaluate the association between the presence of NOD2 risk variants, BT, inflammation, and hepatic encephalopathy (HE).

PATIENTS AND METHODS

This prospective multicenter study included patients with cirrhosis and testing for NOD2 risk variants (p.R702W, p.G908R, c.3020insC, N289S, and c.-958T>C). Patients were evaluated for covert (C) and overt (O) HE. Markers of systemic inflammation (leukocytes, CRP, IL-6, LBP) and immune activation (soluble CD14) as well as bacterial endotoxin (hTRL4 activation) were determined in serum.

RESULTS

Overall, 172 patients (70% men; median age 60 [IQR 54-66] years; MELD 12 [IQR 9-16]; 72% ascites) were included, of whom 53 (31%) carried a NOD2 risk variant. In this cohort, 11% presented with OHE and 27% and CHE. Presence and severity of HE and surrogates of inflammation, BT, and immune activation did not differ between patients with and without a NOD2 risk variant, also not after adjustment for MELD. HE was associated with increased ammonia and systemic inflammation, as indicated by elevated CRP (w/o HE: 7.2 [2.7-16.7]; with HE 12.6 [4.5-29.7] mg/dL; p < 0.001) and elevated soluble CD14 (w/o HE 2592 [2275-3033]; with HE 2755 [2410-3456] ng/mL; p = 0.025).

CONCLUSIONS

The presence of NOD2 risk variants in patients with cirrhosis is not associated with HE and has no marked impact on inflammation, BT, or immune activation. In contrast, the presence of HE was linked to ammonia, the acute phase response, and myeloid cell activation.

Novel Serum Biomarkers Associated With Pediatric Hepatic Encephalopathy: A Systematic Review

BACKGROUND

The pathophysiology of pediatric hepatic encephalopathy (HE) is not well understood. Various serum biomarkers associated with HE may provide insight into its pathology, but their use and interpretation in clinical practice for diagnosis and prognostication remain undetermined. We sought to investigate reported correlations of serum biomarkers with presence and degree of HE in children.

METHODS

We conducted a systematic review of studies examining novel serum biomarkers and cytokines in association with HE that included children on PubMed, Embase, Lilacs, and Scopus. We utilized Covidence for abstract and text review by 2 independent reviewers for each study.

RESULTS

We reviewed 2824 unique publications; 15 met criteria for inclusion. Categories of biomarkers reported were inflammatory cytokines, products of amino acid metabolism, trace elements and vitamins, and hepatic and neuro biomarkers. Of 19 individual biomarkers, only 5 were measured in more than 1 study. Elevations in interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were most commonly reported as associated with HE. Notably, we observed lower average IL-6 and TNF-alpha levels in pediatric-only studies compared to mixed age studies. Overall, high bias and poor applicability to our review question was observed. We encountered low numbers of studies with pediatric focus, and few conducted with low bias study designs.

CONCLUSION

Investigated biomarkers span a large range of categories and suggest potentially useful correlations with HE. Further well-designed prospective biomarker research is necessary to better elucidate the pathogenesis of HE in children and improve early detection and clinical care.

Mild Cognitive Impairment Is Associated with Enhanced Activation of Th17 Lymphocytes in Non-Alcoholic Fatty Liver Disease

Patients with nonalcoholic fatty liver disease (NAFLD) may show mild cognitive impairment (MCI). The mechanisms involved remain unclear. The plasma concentrations of several cytokines and chemokines were measured in 71 NAFLD patients (20 with and 51 without MCI) and 61 controls. Characterization and activation of leukocyte populations and CD4⁺ sub-populations were carried out and analyzed by flow cytometry. We analyzed the cytokines released from CD4⁺ cell cultures and the mRNA expression of transcription factors and receptors in peripheral blood mononuclear cells. The appearance of MCI in NAFLD patients was associated with increased activation of CD4⁺ T lymphocytes, mainly of the Th17 subtype, increased plasma levels of pro-inflammatory and anti-inflammatory cytokines such as IL-17A, IL-23, IL-21, IL-22, IL-6, INF-γ, and IL-13, and higher expression of the CCR2 receptor. Constitutive expression of IL-17 was found in cultures of CD4⁺ cells from MCI patients, reflecting Th17 activation. High IL-13 plasma levels were predictive of MCI and could reflect a compensatory anti-inflammatory response to the increased expression of pro-inflammatory cytokines. This study identified some specific alterations of the immune system associated with the appearance of neurological alterations in MCI patients with NAFLD that could be the basis to improve and restore cognitive functions and quality of life in these patients.

Prediction and prevention of the first episode of overt hepatic encephalopathy in patients with cirrhosis

Hepatic encephalopathy (HE) is one of the most important complications of patients with liver cirrhosis. In addition, HE is associated with a dismal prognosis and has detrimental effects on patients' quality of life. Thus, it is of pivotal importance to identify patients at high risk for overt HE (OHE) in whom primary prophylaxis may be justified. In this narrative review, we aim to provide insight into predictors and prediction tools for a first-time episode of OHE and to scrutinize the current level of evidence of primary prophylaxis. In recent decades, several cognitive tests, composite scores, and blood-based biomarkers have been demonstrated to be predictive of a first-time episode of OHE. Among the best validated are the established tests for minimal HE, such as the Psychometric Hepatic Encephalopathy Score, determination of the critical flicker frequency, Stroop EncephalApp, or the Animal Naming Test. Individualized risk stratification using blood-based biomarkers and cross-sectional imaging (sarcopenia and spontaneous portosystemic shunts) is coming to the fore, but validation in larger multicenter cohorts is often lacking. On the basis of current evidence, a recommendation for primary prophylaxis of a first episode of OHE cannot be made in general. Only 2 studies have investigated the prevention of a first-time OHE episode as the primary endpoint. In this narrative review, we provide a concise overview of the current evidence levels on prediction tools and pharmacological prevention of a first episode of OHE. In addition, we give an outlook on future research targets to improve knowledge on this important topic.

Elevated levels of soluble glycoprotein V - The plasma marker of platelet activation by thrombin in patients with early stage primary biliary cholangitis (PBC)

PURPOSE

There is a growing body of evidence for a prothrombotic tendency in patients with primary biliary cholangitis (PBC). The aim of the study was to evaluate coagulation disorders in patients with early stage PBC compared to healthy controls and evaluation of their relationship with clinical data, with particular emphasis on minimal hepatic encephalopathy (MHE).

PATIENTS AND METHODS

Fifty-one participants (PBC group - 38 patients, all patients but one Child-Pugh A; control group - 13 healthy controls) were included in our prospective, single center study. We assessed the plasma levels of sGPV, plasma procoagulant phospholipids (PPL) and rotational thromboelastometry (ROTEM) profiles in all study participants. Porto-systemic encephalopathy syndrome test was used to assess MHE.

RESULTS

The sGPV levels were higher in the PBC group compared to the controls: 36.07 ​± ​11.32 ​ng/mL vs 27.04 ​± ​11.72 ​ng/mL, p ​= ​0.031. The PPL level was lower in the PBC group compared to controls resulting in increased clotting time in a factor Xa-based coagulation assay: 54.65 (47.83-58.83) sec. vs 45.90 (43.3-50.5) sec., p ​= ​0.0065. PPL levels were correlated with platelet count (rho ​= ​-0.46, p ​= ​0.001). ROTEM parameters did not differ significantly between groups. Coagulation parameters did not differ significantly between patients with and without MHE.

CONCLUSIONS

We have showed increased levels of sGPV - a plasma marker of platelet activation by thrombin in patients with early stage PBC compared to healthy controls. We found no relationship between the coagulation disorders and the occurrence of MHE. The PPL level was lower in the PBC group.

The effects of Ibuprofen and 1, 8- cineol on anxiety and spatial memory in hyperammonemic rats

In hepatic encephalopathy, hyperammonemia (HA) causes cognitive impairment and anxiety by causing neuroinflammation. Ibuprofen and 1,8- cineol have anti-inflammatory and antioxidant properties, respectively. The aim of this study was to evaluate the effects of ibuprofen alone and in combination with 1,8- cineol on anxiety and oxidative stress in a HA rat animal model. For this purpose, 36 rats were divided into six groups (n = 6) including the HA (received intraperitoneally (IP) ammonium acetate 2.5 mg/kg for four week), ibuprofen (induced HA rats that received 15 mg/kg, IP), cineol (induced HA rats that received 5 and 10 mg/kg, IP), Ib + cineol (induced HA rats that received 15 and 10 mg/kg, respectively, IP), and the control groups (received normal saline, IP). Except the HA group, all other groups received the aforementioned treatment for two weeks.. The Morris water maze and elevated plus maze were used to assess cognitive function and anxiety in the animals, respectively. Superoxide dismutase (SOD) activity was measured to evaluate oxidative stress. The mRNA expression levels of interleukin (IL)-6 and IL-1β was assessed by real-time PCR in the animal's brain. The results showed a significant improvement in spatial memory and anxiety of the Ib group compared to the HA group (P < 0.01), but no significant change was observed in SOD activity (P > 0.05). There was a significant improvement in spatial memory and anxiety as well as a significant increase in SOD activity in the Ib + cineol group (P < 0.01) compared to the HA group. These results indicate that the Ib + cineol, not only improve cognitive function and reduce anxiety, also reduce oxidative stress, therefore, the simultaneous use of these two compounds may be useful in improving HA-induced cognitive disorders and anxiety.

The role of brain inflammation and abnormal brain oxygen homeostasis in the development of hepatic encephalopathy

Hepatic encephalopathy (HE) is a frequent complication of chronic liver disease (CLD) and has a complex pathogenesis. Several preclinical and clinical studies have reported the presence of both peripheral and brain inflammation in CLD and their potential impact in the development of HE. Altered brain vascular density and tone, as well as compromised cerebral and systemic blood flow contributing to the development of brain hypoxia, have also been reported in animal models of HE, while a decrease in cerebral metabolic rate of oxygen and cerebral blood flow has consistently been observed in patients with HE. Whilst significant strides in our understanding have been made over the years, evaluating all these mechanistic elements in vivo and showing causal association with development of HE, have been limited through the practical constraints of experimentation. Nonetheless, improvements in non-invasive assessments of different neurophysiological parameters, coupled with techniques to assess changes in inflammatory and metabolic pathways, will help provide more granular insights on these mechanisms. In this special issue we discuss some of the emerging evidence supporting the hypothesis that brain inflammation and abnormal oxygen homeostasis occur interdependently during CLD and comprise important contributors to the development of HE. This review aims at furnishing evidence for further research in brain inflammation and oxygen homeostasis as additional therapeutic targets and potentially diagnostic markers for HE.

Enhanced BDNF and TrkB Activation Enhance GABA Neurotransmission in Cerebellum in Hyperammonemia

Background: Hyperammonemia is a main contributor to minimal hepatic encephalopathy (MHE) in cirrhotic patients. Hyperammonemic rats reproduce the motor incoordination of MHE patients, which is due to enhanced GABAergic neurotransmission in the cerebellum as a consequence of neuroinflammation. In hyperammonemic rats, neuroinflammation increases BDNF by activating the TNFR1–S1PR2–CCR2 pathway. (1) Identify mechanisms enhancing GABAergic neurotransmission in hyperammonemia; (2) assess the role of enhanced activation of TrkB; and (3) assess the role of the TNFR1–S1PR2–CCR2–BDNF pathway. In the cerebellum of hyperammonemic rats, increased BDNF levels enhance TrkB activation in Purkinje neurons, leading to increased GAD65, GAD67 and GABA levels. Enhanced TrkB activation also increases the membrane expression of the γ2, α2 and β3 subunits of GABA_A receptors and of KCC2. Moreover, enhanced TrkB activation in activated astrocytes increases the membrane expression of GAT3 and NKCC1. These changes are reversed by blocking TrkB or the TNFR1–SP1PR2–CCL2–CCR2–BDNF–TrkB pathway. Hyperammonemia-induced neuroinflammation increases BDNF and TrkB activation, leading to increased synthesis and extracellular GABA, and the amount of GABA_A receptors in the membrane and chloride gradient. These factors enhance GABAergic neurotransmission in the cerebellum. Blocking TrkB or the TNFR1–SP1PR2–CCL2–CCR2–BDNF–TrkB pathway would improve motor function in patients with hepatic encephalopathy and likely with other pathologies associated with neuroinflammation.

Golexanolone, a GABAA receptor modulating steroid antagonist, restores motor coordination and cognitive function in hyperammonemic rats by dual effects on peripheral inflammation and neuroinflammation

Aims

Hyperammonemic rats show peripheral inflammation, increased GABAergic neurotransmission and neuroinflammation in cerebellum and hippocampus which induce motor incoordination and cognitive impairment. Neuroinflammation enhances GABAergic neurotransmission in cerebellum by enhancing the TNFR1‐glutaminase‐GAT3 and TNFR1‐CCL2‐TrkB‐KCC2 pathways. Golexanolone reduces GABA_A receptors potentiation by allopregnanolone. This work aimed to assess if treatment of hyperammonemic rats with golexanolone reduces peripheral inflammation and neuroinflammation and restores cognitive and motor function and to analyze underlying mechanisms.

Methods

Rats were treated with golexanolone and effects on peripheral inflammation, neuroinflammation, TNFR1‐glutaminase‐GAT3 and TNFR1‐CCL2‐TrkB‐KCC2 pathways, and cognitive and motor function were analyzed.

Results

Hyperammonemic rats show increased TNFα and reduced IL‐10 in plasma, microglia and astrocytes activation in cerebellum and hippocampus, and impaired motor coordination and spatial and short‐term memories. Treating hyperammonemic rats with golexanolone reversed changes in peripheral inflammation, microglia and astrocytes activation and restored motor coordination and spatial and short‐term memory. This was associated with reversal of the hyperammonemia‐enhanced activation in cerebellum of the TNFR1‐glutaminase‐GAT3 and TNFR1‐CCL2‐TrkB‐KCC2 pathways.

Conclusion

Reducing GABA_A receptors activation with golexanolone reduces peripheral inflammation and neuroinflammation and improves cognitive and motor function in hyperammonemic rats. The effects identified would also occur in patients with hepatic encephalopathy and, likely, in other pathologies associated with neuroinflammation.

Hepatic encephalopathy

Hepatic encephalopathy (HE) is a prognostically relevant neuropsychiatric syndrome that occurs in the course of acute or chronic liver disease. Besides ascites and variceal bleeding, it is the most serious complication of decompensated liver cirrhosis. Ammonia and inflammation are major triggers for the appearance of HE, which in patients with liver cirrhosis involves pathophysiologically low-grade cerebral oedema with oxidative/nitrosative stress, inflammation and disturbances of oscillatory networks in the brain. Severity classification and diagnostic approaches regarding mild forms of HE are still a matter of debate. Current medical treatment predominantly involves lactulose and rifaximin following rigorous treatment of so-called known HE precipitating factors. New treatments based on an improved pathophysiological understanding are emerging.

Evaluation of IL-6 for Stepwise Diagnosis of Minimal Hepatic Encephalopathy in Patients With Liver Cirrhosis

Diagnosis of minimal hepatic encephalopathy (MHE) requires psychometric testing, which is time-consuming and often neglected in clinical practice. Elevated Interleukin-6 (IL-6) serum levels have been linked to MHE. The aim of this study was to investigate the usefulness of IL-6 as a biomarker in a stepwise diagnostic algorithm to detect MHE in patients with liver cirrhosis. A total of 197 prospectively recruited patients without clinical signs of hepatic encephalopathy (HE) served as the development cohort. Another independent cohort consisting of 52 patients served for validation purposes. Psychometric Hepatic Encephalopathy Score (PHES) was applied for the diagnosis of MHE. Fifty (25.4%) patients of the development cohort presented with MHE. Median IL-6 levels were more than twice as high in patients with MHE than in patients without HE (16 vs. 7 pg/mL; P < 0.001). On multivariable logistic regression analysis, higher IL-6 levels (odds ratio 1.036; 95% confidence interval [CI] 1.009-1.064; P = 0.008) remained independently associated with the presence of MHE. IL-6 levels ≥ 8pg/mL discriminated best between patients with and without MHE in receiver operating characteristic (ROC) analysis (area under the ROC 0.751). With a cutoff value of ≥7 pg/mL, further elaborate testing with PHES could be avoided in 38% of all patients with a sensitivity of 90% (95% CI 77%-96%) and a negative predictive value (NPV) of 93% (95% CI 84%-98%). This diagnostic accuracy was confirmed in the validation cohort (sensitivity 94%; NPV 93%). Conclusion: Using IL-6 serum levels as a biomarker in a stepwise diagnostic algorithm to detect MHE could substantially reduce the number of patients requiring testing with PHES and in turn the workload. IL-6 may have especially helped in patients who are unable to perform other screening tests.

Hepatic Encephalopathy and Melatonin

Hepatic encephalopathy (HE) is a severe metabolic syndrome linked with acute/chronic hepatic disorders. HE is also a pernicious neuropsychiatric complication associated with cognitive decline, coma, and death. Limited therapies are available to treat HE, which is formidable to oversee in the clinic. Thus, determining a novel therapeutic approach is essential. The pathogenesis of HE has not been well established. According to various scientific reports, neuropathological symptoms arise due to excessive accumulation of ammonia, which is transported to the brain via the blood–brain barrier (BBB), triggering oxidative stress and inflammation, and disturbing neuronal-glial functions. The treatment of HE involves eliminating hyperammonemia by enhancing the ammonia scavenging mechanism in systemic blood circulation. Melatonin is the sole endogenous hormone linked with HE. Melatonin as a neurohormone is a potent antioxidant that is primarily synthesized and released by the brain’s pineal gland. Several HE and liver cirrhosis clinical studies have demonstrated impaired synthesis, secretion of melatonin, and circadian patterns. Melatonin can cross the BBB and is involved in various neuroprotective actions on the HE brain. Hence, we aim to elucidate how HE impairs brain functions, and elucidate the precise molecular mechanism of melatonin that reverses the HE effects on the central nervous system.

Hyperammonemia Enhances GABAergic Neurotransmission in Hippocampus: Underlying Mechanisms and Modulation by Extracellular cGMP

Rats with chronic hyperammonemia reproduce the cognitive and motor impairment present in patients with hepatic encephalopathy. It has been proposed that enhanced GABAergic neurotransmission in hippocampus may contribute to impaired learning and memory in hyperammonemic rats. However, there are no direct evidences of the effects of hyperammonemia on GABAergic neurotransmission in hippocampus or on the underlying mechanisms. The aims of this work were to assess if chronic hyperammonemia enhances the function of GABA_A receptors in hippocampus and to identify the underlying mechanisms. Activation of GABA_A receptors is enhanced in hippocampus of hyperammonemic rats, as analyzed in a multielectrode array system. Hyperammonemia reduces membrane expression of the GABA transporters GAT1 and GAT3, which is associated with increased extracellular GABA concentration. Hyperammonemia also increases gephyrin levels and phosphorylation of the β3 subunit of GABA_A receptor, which are associated with increased membrane expression of the GABA_A receptor subunits α1, α2, γ2, β3, and δ. Enhanced levels of extracellular GABA and increased membrane expression of GABA_A receptors would be responsible for the enhanced GABAergic neurotransmission in hippocampus of hyperammonemic rats. Increasing extracellular cGMP reverses the increase in GABA_A receptors activation by normalizing the membrane expression of GABA transporters and GABA_A receptors. The increased GABAergic neurotransmission in hippocampus would contribute to cognitive impairment in hyperammonemic rats. The results reported suggest that reducing GABAergic tone in hippocampus by increasing extracellular cGMP or by other means may be useful to improve cognitive function in hyperammonemia and in cirrhotic patients with minimal or clinical hepatic encephalopathy.

Psychometric methods for diagnosing and monitoring minimal hepatic encephalopathy -current validation level and practical use

Hepatic encephalopathy (HE) is cerebral dysfunction caused by liver failure and inflicts 30-40% of patients with liver cirrhosis during their disease course. Clinically manifest HE is often preceded by minimal HE (MHE) - a clinically undetectable cognitive disturbance closely associated with loss of quality of life. Accordingly, detecting and treating MHE improve the patients' daily functioning and prevent HE-related hospital admissions. The scope of this review article is to create an overview of the validation level and usage of psychometric tests used to detect MHE: Portosystemic hepatic encephalopathy test, continuous reaction time test, Stroop EncephalApp, animal naming test, critical flicker frequency test, and inhibitory control test. Our work is aimed at the clinician or scientist who is about to decide on which psychometric test would fit best in their clinic, cohort, or study. First, we outline psychometric test validation obstacles and requirements. Then, we systematically approach the literature on each test and select well-conducted studies to answer the following questions:• Which percentage of patients with cirrhosis does the test deem as having MHE?• Is the test able to predict clinically manifest HE?• Is there a well-known test-retest variation and inter-observer variation?• Is the test able to detect a treatment response?• Is the test result affected by age, educational level, gender, or comorbidities?

Is there an association between non-alcoholic fatty liver disease and cognitive function? A systematic review

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is represented as the most common liver disease worldwide. NAFLD is associated with metabolic risk factors underpinned by insulin resistance, inflammation and endothelial dysfunction, leading to extrahepatic changes in central nervous diseases such as cognitive impairment, Alzheimer's disease and dementia. The aim of the review is to explore the association between NAFLD and cognitive function.

METHODS

Using the PRISMA guidelines, a systematic electronic literature search was conducted in four databases: MEDLINE, PsychINFO, Embase and CINAHL from inception until March 2021. Neuropsychological tests utilised within each study were grouped into relevant cognitive domains including 'general cognition', 'reasoning', 'mental speed, attention and psychomotor speed', 'memory and learning', 'language', 'visuospatial perception' and 'ideas, abstraction, figural creations and mental flexibility'.

RESULTS

Eleven observational studies that involved 7978 participants with a mean age of 51 years were included. Those with NAFLD had poor cognitive performance in three cognitive domains, including 'general cognition', 'mental speed, attention and psychomotor speed', and 'ideas, abstraction, figural creations and mental flexibility'.

CONCLUSION

The observed results from the 11 included studies showed that NAFLD was associated with lower cognitive performance across several domains. However, studies conducted to date are limited to observational designs and are heterogeneous with varying diagnostic tools used to assess cognitive function.

TRIAL REGISTRATION

PROSPERO Registration: CRD42020161640 .

Antibiotics and Liver Cirrhosis: What the Physicians Need to Know

The liver is the primary site of drug metabolism, which can be altered by a variety of diseases affecting the liver parenchyma, especially in patients with liver cirrhosis. The use of antibiotics in patients with cirrhosis is usually a matter of concern for physicians, given the lack of practical knowledge for drug choice and eventual dose adjustments in several clinical scenarios. The aim of the current narrative review is to report, as broadly as possible, basic, and practical knowledge that any physician should have when approaching a patient with liver cirrhosis and an ongoing infection to efficiently choose the best antibiotic therapy.

Differentiation of hepatic encephalopathy from delirium tremens: A case series and review

Hepatic encephalopathy (HE) is an important and potentially life threatening complication in alcoholic patients with decompensated liver function that develop even as they continue drinking. Delirium tremens, on the other hand, is an acute condition resulting from alcohol abstinence in a person dependent on alcohol, making it a life threatening diagnosis that requires intensive care and successful management of the withdrawal. Often in medical wards, these two conditions are mistaken and so is the management plan confused with each other. Making the right diagnosis early on during the hospital course is extremely important in these critical conditions so as to make an appropriate schedule for treatment and a better outcome for the same. A case series of patients who presented with a diagnostic dilemma is reported. Clinical examinations, diagnostic tools to measure the levels of ammonia and liver function tests and hemogram, West Haven criteria and Child-Pugh grading, and clinical scales of these patients are reported. Increased levels of ammonia were present in all the cases. The subtle similarities in the presentation of the two conditions often make it confusing for the clinician to distinguish between them. Using a simple test of measuring ammonia levels in the blood helps in such situations. The detection of raised levels of ammonia in cases of chronic liver disease helps in not just the diagnosis but also is an important prognostic indicator for development of HE.

Minimal hepatic encephalopathy may be present despite the absence of non-invasive and elastography evidence of cirrhosis in patients with primary biliary cholangitis

PURPOSE

Minimal hepatic encephalopathy (MHE) is an important complication of chronic liver disease (CLD); however, MHE burden in patients with primary biliary cholangitis (PBC) has not been determined yet. Therefore, our study aimed to assess the prevalence of MHE in a typical cohort of middle-aged, patients with PBC suspicion of liver fibrosis and to investigate the relationship between MHE, basic laboratory tests and the stage of liver fibrosis.

PATIENTS AND METHODS

Fifty-one patients (38 with PBC and 13 controls), were prospectively enrolled. Portosystemic Encephalopathy-Syndrome test was used to diagnose MHE. Elastography point qualification (ElastPQ) and non-invasive markers (APRI and FIB-4) were used to assess liver fibrosis. The severity of CLD was assessed using the Model of End-Stage Liver Disease (MELD) and Child-Pugh score.

RESULTS

MHE was diagnosed in 9 patients (24.3%) with PBC and none in the control group. As many as 44.4% of the patients with MHE had neither advanced fibrosis nor cirrhosis, as demonstrated using non-invasive markers of liver fibrosis or ElastPQ. The MELD score was the only predictor of MHE with cut-off value 8.5 [AUC ​= ​0.753, CI_95% ​= ​0.569 to 0.938)] with sensitivity of 56%, specificity of 85% and accuracy of the test of 78%. Non-invasive markers of liver fibrosis and ElastPQ did not predict MHE.

CONCLUSIONS

MHE may occur in PBC despite no evidence of advanced liver fibrosis or cirrhosis. The slightly elevated MELD score may indicate a substantially increased risk of MHE in patients with PBC.

The Dual Role of the GABAA Receptor in Peripheral Inflammation and Neuroinflammation: A Study in Hyperammonemic Rats

Cognitive and motor impairment in minimal hepatic encephalopathy (MHE) are mediated by neuroinflammation, which is induced by hyperammonemia and peripheral inflammation. GABAergic neurotransmission in the cerebellum is altered in rats with chronic hyperammonemia. The mechanisms by which hyperammonemia induces neuroinflammation remain unknown. We hypothesized that GABA_A receptors can modulate cerebellar neuroinflammation. The GABA_A antagonist bicuculline was administrated daily (i.p.) for four weeks in control and hyperammonemic rats. Its effects on peripheral inflammation and on neuroinflammation as well as glutamate and GABA neurotransmission in the cerebellum were assessed. In hyperammonemic rats, bicuculline decreases IL-6 and TNFα and increases IL-10 in the plasma, reduces astrocyte activation, induces the microglia M2 phenotype, and reduces IL-1β and TNFα in the cerebellum. However, in control rats, bicuculline increases IL-6 and decreases IL-10 plasma levels and induces microglial activation. Bicuculline restores the membrane expression of some glutamate and GABA transporters restoring the extracellular levels of GABA in hyperammonemic rats. Blocking GABA_A receptors improves peripheral inflammation and cerebellar neuroinflammation, restoring neurotransmission in hyperammonemic rats, whereas it induces inflammation and neuroinflammation in controls. This suggests a complex interaction between GABAergic and immune systems. The modulation of GABA_A receptors could be a suitable target for improving neuroinflammation in MHE.

Current approach to treatment of minimal hepatic encephalopathy in patients with liver cirrhosis

Minimal hepatic encephalopathy (MHE) corresponds to the earliest stage of hepatic encephalopathy (HE). MHE does not present clinically detectable neurological-psychiatric abnormalities but is characterized by imperceptible neurocognitive alterations detected during routine clinical examination via neuropsychological or psychometrical tests. MHE may affect daily activities and reduce job performance and quality of life. MHE can increase the risk of accidents and may develop into overt encephalopathy, worsening the prognosis of patients with liver cirrhosis. Despite a lack of consensus on the therapeutic indication, interest in finding novel strategies for prevention or reversion has led to numerous clinical trials; their results are the main objective of this review. Many studies address the treatment of MHE, which is mainly based on the strategies and previous management of overt HE. Current alternatives for the management of MHE include measures to maintain nutritional status while avoiding sarcopenia, and manipulation of intestinal microbiota with non-absorbable disaccharides such as lactulose, antibiotics such as rifaximin, and administration of different probiotics. This review analyzes the results of clinical studies that evaluated the effects of different treatments for MHE.

A multi-omic study for uncovering molecular mechanisms associated with hyperammonemia-induced cerebellar function impairment in rats

Patients with liver cirrhosis may develop covert or minimal hepatic encephalopathy (MHE). Hyperammonemia (HA) and peripheral inflammation play synergistic roles in inducing the cognitive and motor alterations in MHE. The cerebellum is one of the main cerebral regions affected in MHE. Rats with chronic HA show some motor and cognitive alterations reproducing neurological impairment in cirrhotic patients with MHE. Neuroinflammation and altered neurotransmission and signal transduction in the cerebellum from hyperammonemic (HA) rats are associated with motor and cognitive dysfunction, but underlying mechanisms are not completely known. The aim of this work was to use a multi-omic approach to study molecular alterations in the cerebellum from hyperammonemic rats to uncover new molecular mechanisms associated with hyperammonemia-induced cerebellar function impairment. We analyzed metabolomic, transcriptomic, and proteomic data from the same cerebellums from control and HA rats and performed a multi-omic integrative analysis of signaling pathway enrichment with the PaintOmics tool. The histaminergic system, corticotropin-releasing hormone, cyclic GMP-protein kinase G pathway, and intercellular communication in the cerebellar immune system were some of the most relevant enriched pathways in HA rats. In summary, this is a good approach to find altered pathways, which helps to describe the molecular mechanisms involved in the alteration of brain function in rats with chronic HA and to propose possible therapeutic targets to improve MHE symptoms.

Disturbance of the Glutamate-Glutamine Cycle, Secondary to Hepatic Damage, Compromises Memory Function

Glutamate fulfils many vital functions both at a peripheral level and in the central nervous system (CNS). However, hyperammonemia and hepatic failure induce alterations in glutamatergic neurotransmission, which may be the main cause of hepatic encephalopathy (HE), an imbalance which may explain damage to both learning and memory. Cognitive and motor alterations in hyperammonemia may be caused by a deregulation of the glutamate-glutamine cycle, particularly in astrocytes, due to the blocking of the glutamate excitatory amino-acid transporters 1 and 2 (EAAT1, EAAT2). Excess extracellular glutamate triggers mechanisms involving astrocyte-mediated inflammation, including the release of Ca2+-dependent glutamate from astrocytes, the appearance of excitotoxicity, the formation of reactive oxygen species (ROS), and cell damage. Glutamate re-uptake not only prevents excitotoxicity, but also acts as a vital component in synaptic plasticity and function. The present review outlines the evidence of the relationship between hepatic damage, such as that occurring in HE and hyperammonemia, and changes in glutamine synthetase function, which increase glutamate concentrations in the CNS. These conditions produce dysfunction in neuronal communication. The present review also includes data indicating that hyperammonemia is related to the release of a high level of pro-inflammatory factors, such as interleukin-6, by astrocytes. This neuroinflammatory condition alters the function of the membrane receptors, such as N-methyl-D-aspartate (NMDA), (α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) AMPA, and γ-aminobutyric acid (GABA), thus affecting learning and spatial memory. Data indicates that learning and spatial memory, as well as discriminatory or other information acquisition processes in the CNS, are damaged by the appearance of hyperammonemia and, moreover, are associated with a reduction in the production of cyclic guanosine monophosphate (cGMP). Therefore, increased levels of pharmacologically controlled cGMP may be used as a therapeutic tool for improving learning and memory in patients with HE, hyperammonemia, cerebral oedema, or reduced intellectual capacity.

The Psychometric Hepatic Encephalopathy Syndrome score does not correlate with blood ammonia, endotoxins or markers of inflammation in patients with cirrhosis

Background

The pathogenesis of hepatic encephalopathy (HE) remains unclear but impaired clearance of gut-derived neurotoxins and increased systemic inflammation are thought to play key roles. The diagnosis is based on detection of neurophysiological and neuropsychometric abnormalities. The Psychometric Hepatic Encephalopathy Score (PHES) have been found to correlate with markers of systematic inflammation including interleukin 6, C-reactive protein (CRP) and tumor necrosis factor-α (TNF-α). This study explores the associations between the PHES score and systemic inflammation, endotoxins and disease severity using baseline data from a trial involving patients with cirrhosis and minimal or no HE (NCT01769040).

Methods

Arterial blood was obtained during hepatic vein catheterization, from 54 patients [median age 55 (range, 33-70) years; 83% men] with decompensated but stable cirrhosis. None had clinical evidence of HE but 34 (55.6%) had an abnormal PHES score indicating the presence of minimal HE. Relationships were sought between the PHES score and markers of systemic inflammation, high sensitivity-CRP, cytokines (SDF-1α, TGF-b1, IP-10, IL-6, 10 and 18, and TNF-α; lipopolysaccharide (LPS), the lipopolysaccharide binding protein (LBP) and soluble CD14 (sCD14); and the blood ammonia.

Results

No significant relationships were found between the PHES score and any of the variables tested with the single exception of the correlation with serum IL-6 (r=-0.29, 95% confidence interval, -0.53 to -0.02, P=0.031). No independent predictors of the PHES score were identified in regression analyses.

Conclusions

No predictive associations were identified between the PHES scores and circulating blood ammonia, endotoxins, or markers of systemic inflammation in this patient population.

Similarities, Differences, and Potential Synergies in the Mechanism of Action of Albumin Dialysis Using the MARS Albumin Dialysis Device and the CytoSorb Hemoperfusion Device in the Treatment of Liver Failure

INTRODUCTION

Liver failure is characterized by compromised hepatic detoxification, protein synthesis, and metabolic derangements leading to an accumulation of a broad spectrum of water-soluble and lipophilic toxins as well as immune system mediators. Exploring complex detoxification mechanisms to therapeutically target those components, this article will focus on similarities, differences, and potential synergies in the mechanism of albumin dialysis and hemoperfusion.

METHODS

An in vitro two-compartment model for the comparison of liver support techniques was used to compare MARS albumin dialysis modified with novel charcoal adsorbents to CytoSorb hemoperfusion with added hemodialysis for effects on marker molecule removal.

RESULTS

MARS and CytoSorb performed similar in the removal of water-soluble toxins. Ammonia removal was increased using CytoSorb. CytoSorb lead to a statistically significant reduction of albumin-bound toxins, total bilirubin and subfractions. Bile acid removal was comparable. MARS demonstrated no removal of cytokines interleukin (IL)-6 and tumor necrosis factor-alpha (TNF-α), whereas CytoSorb allowed for near complete removal. Notably, CytoSorb displayed 50% of lipophilic substance and cytokine removal during the first hour of treatment.

CONCLUSION

Compared to MARS, CytoSorb hemoperfusion leads to an initially fast removal of cytokines, TNF-α and IL-6, as well as reduction of albumin-bound toxins such as indirect bilirubin and bile acids in our model. The initial removal is also associated with removal of albumin.

Prediction of minimal encephalopathy in patients with HCV-related cirrhosis using albumin-bilirubin, platelets-albumin-bilirubin score, albumin-bilirubin-platelets grade and ammonia level

Background

Minimal hepatic encephalopathy (MHE) is a complication of liver cirrhosis causing low quality of life, driving skills and higher traffic violation. The neuro-psychometric tests are the gold standard but difficult clinically and time-consuming. The aim was to assess albumin-bilirubin (ALBI), platelets-albumin-bilirubin (PALBI) score, albumin-bilirubin-platelets (ALBI-PLT) grade and ammonia level as MHE predictors. All the patients (n = 257) underwent critical flicker frequency number connection, serial dotting and digit symbol test for MHE diagnosis (n = 166, 64.6%). Liver function, INR, CBC and arterial ammonia were measured.

Results

There was statistically significant difference (p < 0.05) between MHE patients and those without as regards ammonia (86.59 ± 23.25 vs. 63.56 ± 24.2 μmol/L), ALBI score (−2.13 ± 0.53 vs. −2.49 ± 0.38), PALBI score (−2.33 ± 0.39 vs. −2.55 ± 0.26) and ALBI-PLT (3.98 ± 0.49 vs. 3.70 ± 0.56). Patients with MHE were mainly Child-Pugh B and C and also ALBI grade 2 and 3. For MHE discrimination, ALBI, PALBI, ALBI-PLT and ammonia had the following cutoffs >−2.36 (57.23% sensitivity, 77.78% specificity), >−2.5 (60.84% sensitivity, 67.9% specificity), > 3 (87.35% sensitivity, 27.16% specificity) and > 76.5 (69% sensitivity, 72.5% specificity) respectively (p = 0.001). On comparison of the area under the curve, ALBI is comparable to PALBI (p = 0.245) and ammonia (p = 0.603). The ALBI-PLT is inferior to ALBI (p = 0.018) and ammonia (p = 0.021) but comparable to PALBI (p = 0.281). ALBI (odds = 5.64), PALBI (odds = 7.86), ALBI-PLT (odds = 2.86), ammonia (odds = 1.05), Child-Pugh score (odds = 2.13), MELD (odds = 1.26) are independent predictors of MHE.

Conclusion

ALBI, PALBI and ammonia are clinical useful model for MHE prediction.

Chronic hyperammonemia induces peripheral inflammation that leads to cognitive impairment in rats: Reversed by anti-TNF-α treatment

BACKGROUND & AIMS

Chronic hyperammonemia induces neuroinflammation which mediates cognitive impairment. How hyperammonemia induces neuroinflammation remains unclear. We aimed to assess whether: chronic hyperammonemia induces peripheral inflammation, and whether this then contributes to neuroinflammation, altered neurotransmission and impaired spatial learning - before assessing whether this neuroinflammation and impairment is reversible following hyperammonemia elimination or treatment of peripheral inflammation with anti-TNF-α.

METHODS

Chronic hyperammonemia was induced by feeding rats an ammonia-containing diet. Peripheral inflammation was analyzed by measuring PGE2, TNF-α, IL-6 and IL-10. We tested whether chronic anti-TNF-α treatment improves peripheral inflammation, neuroinflammation, membrane expression of glutamate receptors in the hippocampus and spatial learning.

RESULTS

Hyperammonemic rats show a rapid and reversible induction of peripheral inflammation, with increased pro-inflammatory PGE2, TNF-α and IL-6, followed at around 10 days by reduced anti-inflammatory IL-10. Peripheral anti-TNF-α treatment prevents peripheral inflammation induction and the increase in IL-1b and TNF-α and microglia activation in hippocampus of the rats, which remain hyperammonemic. This is associated with prevention of the altered membrane expression of glutamate receptors and of the impairment of spatial memory assessed in the radial and Morris water mazes.

CONCLUSIONS

This report unveils a new mechanism by which chronic hyperammonemia induces neurological alterations: induction of peripheral inflammation. This suggests that reducing peripheral inflammation by safe procedures would improve cognitive function in patients with minimal hepatic encephalopathy.

LAY SUMMARY

This article unveils a new mechanism by which chronic hyperammonemia induces cognitive impairment in rats: chronic hyperammonemia per se induces peripheral inflammation, which mediates many of its effects on the brain, including induction of neuroinflammation, which alters neurotransmission, leading to cognitive impairment. It is also shown that reducing peripheral inflammation by treating rats with anti-TNF-α, which does not cross the blood-brain barrier, prevents hyperammonemia-induced neuroinflammation, alterations in neurotransmission and cognitive impairment.

Minimal Hepatic Encephalopathy: Effect of H. pylori infection and small intestinal bacterial overgrowth treatment on clinical outcomes

The effect Helicobacter pylori (Hp) infection and small intestinal bacterial over growth (SIBO) in minimal hepatic encephalopathy (MHE) is not well understood. The aim of the study was to determine the effect of eradication of Hp infection and SIBO treatment on MHE in patients with cirrhosis. Patients with cirrhosis were enrolled and MHE was determined by psychometric tests and critical flicker frequency analysis. Hp infection and SIBO were assessed by urea breath and Hydrogen breath tests respectively in patients with cirrhosis and in healthy volunteers. Patients with Hp infection and SIBO were given appropriate treatment. At six weeks follow-up, presence of Hp infection, SIBO and MHE status was reassessed. Ninety patients with cirrhosis and equal number of healthy controls were included. 55 (61.1%) patients in the cirrhotic group were diagnosed to have underlying MHE. Among cirrhotic group, Hp infection was present in 28 with MHE (50.9%) vs. in 15 without MHE (42.8%) (p = 0.45). Similarly, SIBO was present in 17 (30.9%) vs. 11 (31.4%) (p = 0.95) in patients with and without MHE respectively. In comparison with healthy controls, patients with cirrhosis were more frequently harboring Hp and SIBO (47.7% vs. 17.7% (p < 0.001) and 31.1% vs. 4.4% (p < 0.001) respectively. On follow-up, all patients showed evidence of eradication of Hp and SIBO infection. Treatment of SIBO significantly improved the state of MHE in cirrhotics, however eradication of Hp infection did not improve MHE significantly. Additionally, patients with low Model for End-Stage Liver Disease (MELD) score and belonging to Child class B had significantly better improvement in MHE. A large number of patients with cirrhosis had either active Hp infection or SIBO with or without MHE, compared to healthy controls. Treatment of SIBO significantly improved MHE in patients with cirrhosis, whereas eradication of Hp did not affect the outcome of MHE in these patients.

Extracellular Vesicles from Hyperammonemic Rats Induce Neuroinflammation and Motor Incoordination in Control Rats

Minimal hepatic encephalopathy is associated with changes in the peripheral immune system which are transferred to the brain, leading to neuroinflammation and thus to cognitive and motor impairment. Mechanisms by which changes in the immune system induce cerebral alterations remain unclear. Extracellular vesicles (EVs) seem to play a role in this process in certain pathologies. The aim of this work was to assess whether EVs play a role in the induction of neuroinflammation in cerebellum and motor incoordination by chronic hyperammonemia. We characterized the differences in protein cargo of EVs from plasma of hyperammonemic and control rats by proteomics and Western blot. We assessed whether injection of EVs from hyperammonemic to normal rats induces changes in neuroinflammation in cerebellum and motor incoordination similar to those exhibited by hyperammonemic rats. We found that hyperammonemia increases EVs amount and alters their protein cargo. Differentially expressed proteins are mainly associated with immune system processes. Injected EVs enter Purkinje neurons and microglia. Injection of EVs from hyperammonemic, but not from control rats, induces motor incoordination, which is mediated by neuroinflammation, microglia and astrocytes activation and increased IL-1β, TNFα, its receptor TNFR1, NF-κB in microglia, glutaminase I, and GAT3 in cerebellum. Plasma EVs from hyperammonemic rats carry molecules necessary and sufficient to trigger neuroinflammation in cerebellum and the mechanisms leading to motor incoordination.

Sustained hyperammonemia induces TNF-a IN Purkinje neurons by activating the TNFR1-NF-κB pathway

Background

Patients with liver cirrhosis may develop hepatic encephalopathy. Rats with chronic hyperammonemia exhibit neurological alterations mediated by peripheral inflammation and neuroinflammation. Motor incoordination is due to increased TNF-a levels and activation of its receptor TNFR1 in the cerebellum.

The aims were to assess (a) whether peripheral inflammation is responsible for TNF-a induction in hyperammonemic rats, (b) the cell type(s) in which TNF-a is increased, (c) whether this increase is associated with increased nuclear NF-κB and TNFR1 activation, (d) the time course of TNF-a induction, and (e) if TNF-a is induced in the Purkinje neurons of patients who die with liver cirrhosis.

Methods

We analyzed the level of TNF-a mRNA and NF-κB in microglia, astrocytes, and Purkinje neurons in the cerebellum after 1, 2, and 4 weeks of hyperammonemia. We assessed whether preventing peripheral inflammation by administering an anti-TNF-a antibody prevents TNF-a induction. We tested whether TNF-a induction is reversed by R7050, which inhibits the TNFR1-NF-κB pathway, in ex vivo cerebellar slices.

Results

Hyperammonemia induced microglial and astrocyte activation at 1 week. This was followed by TNF-a induction in both glial cell types at 2 weeks and in Purkinje neurons at 4 weeks. The level of TNF-a mRNA increased in parallel with the TNF-a protein level, indicating that TNF-a was synthesized in Purkinje cells. This increase was associated with increased NF-κB nuclear translocation. The nuclear translocation of NF-κB and the increase in TNF-a were reversed by R7050, indicating that they were mediated by the activation of TNFR1. Preventing peripheral inflammation with an anti-TNF-a antibody prevents TNF-a induction.

Conclusion

Sustained (4 weeks) but not short-term hyperammonemia induces TNF-a in Purkinje neurons in rats. This is mediated by peripheral inflammation. TNF-a is also increased in the Purkinje neurons of patients who die with liver cirrhosis. The results suggest that hyperammonemia induces TNF-a in glial cells and that TNF-a released by glial cells activates TNFR1 in Purkinje neurons, leading to NF-κB nuclear translocation and the induction of TNF-a expression, which may contribute to the neurological alterations observed in hyperammonemia and hepatic encephalopathy.

Cerebral edema and liver disease: Classic perspectives and contemporary hypotheses on mechanism

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.

Raised serum Interleukin-6 identifies patients with liver cirrhosis at high risk for overt hepatic encephalopathy

BACKGROUND

Systemic inflammation is a driving force for the development of hepatic encephalopathy and recent studies demonstrated that elevated Interleukin-6 (IL-6) serum levels are associated with the presence of minimal hepatic encephalopathy in patients with liver cirrhosis.

AIM

To test the hypothesis that IL-6 is a suitable marker to identify patients with liver cirrhosis at high risk for the development of overt hepatic encephalopathy.

METHODS

201 patients were included into this prospective cohort study and were followed for a mean time of 322 days. Covert hepatic encephalopathy was diagnosed according to the West-Haven criteria (hepatic encephalopathy grade 1) and with the portosystemic encephalopathy (PSE) test.

RESULTS

The cumulative incidence of overt hepatic encephalopathy was higher in patients with IL-6 levels above the median of 9 pg/mL than in patients with IL-6 levels at or below the median (35.6% vs 1.9%, P < .001). After adjustment for covert hepatic encephalopathy, history of overt hepatic encephalopathy, C-reactive protein (CRP) and model for end-stage liver disease (MELD), IL-6 levels above the median remained independently associated with the development of overt hepatic encephalopathy. The predictive performance of IL-6 regarding the development of overt hepatic encephalopathy during the next 180 days (AUROC, 0.931) was numerically higher than that of MELD (AUROC, 0.841) or CRP (AUROC, 0.835). In patients without prior overt hepatic encephalopathy, the predictive performance of IL-6 (AUROC, 0.966) was even significantly higher than that of MELD (AUROC 0.843) or CRP (AUROC 0.850). The ideal cut-off for IL-6 in this setting was 23.5 pg/mL with a sensitivity and specificity of 89.3% and 89.5% respectively.

CONCLUSION

IL-6 serum levels are closely linked to the development of overt hepatic encephalopathy in patients with liver cirrhosis.

Selective improvement by rifaximin of changes in the immunophenotype in patients who improve minimal hepatic encephalopathy

Background

Minimal hepatic encephalopathy (MHE) in cirrhotic patients is associated with specific changes in parameters of the immune system reflecting a more pro-inflammatory environment than in patients without MHE. The aims of this work were to assess the effects of rifaximin treatment of cirrhotic patients with MHE on: (1) MHE; (2) intermediate (CD14⁺⁺CD16⁺) pro-inflammatory monocytes; (3) expression of early activation marker CD69 in T lymphocytes; (4) autoreactive CD4⁺CD28⁻ T lymphocytes; (5) differentiation of CD4⁺ T lymphocytes to Th follicular and Th22; (6) serum IgG levels; and (7) levels of some pro-inflammatory cytokines.

Methods

These parameters were measured by immunophenotyping and cytokine profile analysis in 30 controls without liver disease, 30 cirrhotic patients without MHE and 22 patients with MHE. Patients with MHE were treated with rifaximin and the same parameters were measured at 3 and 6 months of treatment. We assessed if changes in these parameters are different in patients who improve MHE (responders) and those who remain in MHE (non-responders).

Results

Rifaximin improved MHE in 59% of patients with MHE. In these responder patients rifaximin normalized all alterations in the immune system measured while in non-responders it normalizes only IL-6, CCL20, and differentiation of T lymphocytes to Th22. Non-responder patients do not show increased expression of CD69 before treatment.

Conclusions

Rifaximin normalizes changes in the immune system in patients who improve MHE but not in non-responders. Some alterations before treatment are different in responders and non-responders. Understanding these differences may identify predictors of the response of MHE to rifaximin.

Critical flickering frequency test: a diagnostic tool for minimal hepatic encephalopathy

BACKGROUND

Minimal hepatic encephalopathy (MHE) is underestimated. It affects 30-55% of patients with liver cirrhosis and can change their daily functions. Psychometric tests are sensitive in diagnosing MHE, but interpretation is difficult. Availability of a simpler diagnostic tool for MHE is mandatory. Critical flicker frequency (CFF) is a simple diagnostic test.

AIM

The aim of this study was to assess the diagnostic accuracy of CFF test for MHE.

PATIENTS AND METHODS

A total of 86 patients with cirrhosis with negative history of overt hepatic encephalopathy were included. History, clinical examination, laboratory investigations, and abdominal ultrasonography data were collected. Arabic version of number connection test, serial dotting test, and line tracing test were done. Total psychometric hepatic encephalopathy score (PHES) was used to diagnose MHE. CFF was done for all patients with MHE diagnosis at 39 Hz.

RESULTS

Of the 86 patients, 45 (52.3%) had MHE with PHES. Patients with MHE had significantly older age, presentation with jaundice, ascites, lower hemoglobin level, lower serum albumin, prolonged INR, higher Child class and score (P≤0.001), and higher model of end stage liver disease score (P=0.001) than patients without MHE. In comparison with PHES, CFF has a sensitivity of 91.1±8.32%, specificity of 92.7±7.96%, positive predictive value of 93.2±7.44%, and negative predictive value of 90.4±8.91%. In receiver operating characteristic curve, CFF is excellent in diagnosis of MHE, with area under the curve 0.937 (P<0.001).

CONCLUSION

MHE is common among patients with liver cirrhosis. CFF is a simple, rapid, noninvasive test for diagnosis of MHE, with a very good accuracy at 39 Hz.

Predicting Overt Hepatic Encephalopathy for the Population With Cirrhosis

Hepatic encephalopathy (HE) is associated with poor quality of life, sharply increased mortality, repeated hospitalizations, falls, and motor vehicle accidents. HE manifests with a dynamic spectrum of severity. Overt HE is clinically obvious disorientation, even coma. Although multiple strategies are available to characterize early-stage HE, data are limited that validate these methods in predicting overt HE, many are impractical in clinical practice, and test cutoffs relevant to the average patient clinicians manage are lacking. To accurately and efficiently classify the risk of overt HE in the population with cirrhosis, novel strategies may be needed. Herein, we review the potential competing strategies for the prediction of overt HE. Conclusion: We propose refining diagnostic cutoffs for tests that are designed to define early HE, using overt HE as a gold standard and expanding prediction tools by using measures of components from the risk pathway for HE.

Peripheral inflammation induces neuroinflammation that alters neurotransmission and cognitive and motor function in hepatic encephalopathy: Underlying mechanisms and therapeutic implications

Several million patients with liver cirrhosis suffer minimal hepatic encephalopathy (MHE), with mild cognitive and coordination impairments that reduce their quality of life and life span. Hyperammonaemia and peripheral inflammation act synergistically to induce these neurological alterations. We propose that MHE appearance is because of the changes in peripheral immune system, which are transmitted to brain, leading to neuroinflammation that alters neurotransmission leading to cognitive and motor alterations. We summarize studies showing that MHE in cirrhotic patients is associated with alterations in the immune system and that patients died with HE show neuroinflammation in cerebellum, with microglial and astrocytic activation and Purkinje cell loss. We also summarize studies in animal models of MHE on the role of peripheral inflammation in neuroinflammation induction, how neuroinflammation alters neurotransmission and how this leads to cognitive and motor alterations. These studies identify therapeutic targets and treatments that improve cognitive and motor function. Rats with MHE show neuroinflammation in hippocampus and altered NMDA and AMPA receptor membrane expression, which impairs spatial learning and memory. Neuroinflammation in cerebellum is associated with altered GABA transporters and extracellular GABA, which impair motor coordination and learning in a Y maze. These alterations are reversed by treatments that reduce peripheral inflammation (anti-TNFα, ibuprofen), neuroinflammation (sulphoraphane, p38 inhibitors), GABAergic tone (bicuculline, pregnenolone sulphate) or increase extracellular cGMP (sildenafil or cGMP). The mechanisms identified would also occur in other chronic diseases associated with inflammation, aging and some mental and neurodegenerative diseases. Treatments that improve MHE may also be beneficial to treat these pathologies.

Bicuculline Reduces Neuroinflammation in Hippocampus and Improves Spatial Learning and Anxiety in Hyperammonemic Rats. Role of Glutamate Receptors

Patients with liver cirrhosis may develop minimal hepatic encephalopathy (MHE) with mild cognitive impairment. Hyperammonemia is a main contributor to cognitive impairment in MHE, which is mediated by neuroinflammation. GABAergic neurotransmission is altered in hyperammonemic rats. We hypothesized that, in hyperammonemic rats, (a) enhanced GABAergic tone would contribute to induce neuroinflammation, which would be improved by reducing GABAergic tone by chronic bicuculline treatment; (b) this would improve spatial learning and memory impairment; and (c) modulation of glutamatergic neurotransmission would mediate this cognitive improvement. The aim of this work was to assess the above hypotheses. Bicuculline was administrated intraperitoneally once a day for 4 weeks to control and hyperammonemic rats. The effects of bicuculline on microglia and astrocyte activation, IL-1β content, on membrane expression of AMPA and NMDA glutamate receptors subunits in the hippocampus and on spatial learning and memory as well as anxiety were assessed. Treatment with bicuculline reduces astrocyte activation and IL-1β but not microglia activation in the hippocampus of hyperammonemic rats. Bicuculline reverses the changes in membrane expression of AMPA receptor subunits GluA1 and GluA2 and of the NR2B (but not NR1 and NR2A) subunit of NMDA receptors. Bicuculline improves spatial learning and working memory and decreases anxiety in hyperammonemic rats. In hyperammonemia, enhanced activation of GABAA receptors in the hippocampus contributes to some but not all aspects of neuroinflammation, to altered glutamatergic neurotransmission and to impairment of spatial learning and memory as well as anxiety, all of which are reversed by reducing activation of GABAA receptors with bicuculline.

Biological Activities of Lactose-Based Prebiotics and Symbiosis with Probiotics on Controlling Osteoporosis, Blood-Lipid and Glucose Levels

Lactose-based prebiotics are synthesized by enzymatic- or microbial- biotransformation of lactose and have unique functional values. In this comprehensive review article, the biochemical mechanisms of controlling osteoporosis, blood-lipid, and glucose levels by lactose-based prebiotics and symbiosis with probiotics are reported along with the results of clinical investigations. Interaction between lactose-based prebiotics and probiotics reduces osteoporosis by (a) transforming insoluble inorganic salts to soluble and increasing their absorption to gut wall; (b) maintaining and protecting mineral absorption surface in the intestine; (c) increasing the expression of calcium-binding proteins in the gut wall; (d) remodeling osteoclasts and osteoblasts formation; (e) releasing bone modulating factors; and (f) degrading mineral complexing phytic acid. Lactose-based prebiotics with probiotics control lipid level in the bloodstream and tissue by (a) suppressing the expressions of lipogenic- genes and enzymes; (b) oxidizing fatty acids in muscle, liver, and adipose tissue; (c) binding cholesterol with cell membrane of probiotics and subsequent assimilation by probiotics; (d) enzymatic-transformations of bile acids; and (e) converting cholesterol to coprostanol and its defecation. Symbiosis of lactose-based prebiotics with probiotics affect plasma glucose level by (a) increasing the synthesis of gut hormones plasma peptide-YY, glucagon-like peptide-1 and glucagon-like peptide-2 from entero-endocrine L-cells; (b) altering glucose assimilation and metabolism; (c) suppressing systematic inflammation; (d) reducing oxidative stress; and (e) producing amino acids. Clinical investigations show that lactose-based prebiotic galacto-oligosaccharide improves mineral absorption and reduces hyperlipidemia. Another lactose-based prebiotic, lactulose, improves mineral absorption, and reduces hyperlipidemia and hyperglycemia. It is expected that this review article will be of benefit to food technologists and medical practitioners.

Bacterial translocation in patients with liver cirrhosis: physiology, clinical consequences, and practical implications

The gut liver axis is an operative unit that works to protect the human body against potentially harmful substances and microorganisms, maintaining the homeostasis of the immune system. Liver cirrhosis profoundly alters this complex system. The intestine becomes more permeable allowing the translocation of bacteria, bacterial products and fragments into the portal circulation, triggering an abnormal local and systemic inflammatory response and a condition of perpetual immunologic alarm. This immune-inflammatory disorder related to dysbiosis is involved in the development of liver damage and liver cirrhosis complications and increases intestinal permeability in a vicious circle. Areas covered: The most relevant studies on bacterial translocation, the mechanism of intestinal barrier dysfunction and its consequences in patients with liver cirrhosis have been revised through a PubMed search. Data have been discussed with particular regard to their significance in clinical practice. Expert commentary: The assessment of bacterial translocation and intestinal permeability is not currently used in clinical practice but may be useful to stratify patients' prognosis.

Learning and Memory Impairments in Patients with Minimal Hepatic Encephalopathy are Associated with Structural and Functional Connectivity Alterations in Hippocampus

Patients with minimal hepatic encephalopathy (MHE) show mild cognitive impairment associated with alterations in attentional and executive networks. There are no studies evaluating the relationship between memory in MHE and structural and functional connectivity (FC) changes in the hippocampal system. This study aimed to evaluate verbal learning and long-term memory in cirrhotic patients with (C-MHE) and without MHE (C-NMHE) and healthy controls. We assessed the relationship between alterations in memory and the structural integrity and FC of the hippocampal system. C-MHE patients showed impairments in learning, long-term memory, and recognition, compared to C-NMHE patients and controls. Cirrhotic patients showed reduced fimbria volume compared to controls. Larger volumes in hippocampus subfields were related to better memory performance in C-NMHE patients and controls. C-MHE patients presented lower FC between the L-presubiculum and L-precuneus than C-NMHE patients. Compared to controls, C-MHE patients had reduced FC between L-presubiculum and subiculum seeds and bilateral precuneus, which correlated with cognitive impairment and memory performance. Alterations in the FC of the hippocampal system could contribute to learning and long-term memory impairments in C-MHE patients. This study demonstrates the association between alterations in learning and long-term memory and structural and FC disturbances in hippocampal structures in cirrhotic patients.

Systemic inflammation without gliosis mediates cognitive deficits through impaired BDNF expression in bile duct ligation model of hepatic encephalopathy

Chronic liver disease per se induces neuroinflammation that contributes to cognitive deficits in hepatic encephalopathy (HE). However, the processes by which pro-inflammatory molecules result in cognitive impairment still remains unclear. In the present study, a significant increase in the activity of liver function enzymes viz. alanine transaminase (ALT), aspartate transaminase (AST) and alkaline phosphatase (ALP) was observed along with increase in plasma ammonia levels after four weeks of bile duct ligation (BDL) in rats suggesting hepatocellular damage. A significant increase was observed in mRNA expression of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α) and monocyte chemoattractant protein-1 (MCP-1) in brain regions and liver of BDL rats. Concomitantly, IL-6, TNF-α and MCP-1 protein levels were also increased in brain regions, liver and serum of BDL rats suggesting the involvement of blood-brain-axis in inflammatory response. However, a significant decrease was observed in glial fibrillary acidic protein (GFAP) and ionized calcium-binding adaptor molecule-1 (Iba-1) expression at transcriptional and translation level in brain of BDL rats. Immunohistochemical and flowcytometric analysis revealed reduced number of GFAP-immunopositive astrocytes and Iba1-immunopositive microglia in the brain regions of BDL rats. Further, a significant decline was observed in cognitive functions in BDL rats assessed using Morris water maze and novel object recognition tests. Expression of pro and mature form of brain derived neurotrophic factor (BDNF) and its upstream transcription element showed significant reduction in brain of BDL rats. Taken together, the results of the present study suggest that systemic inflammation and reduced expression of BDNF and its upstream transcription factor plays a key role in cognitive decline in HE.

Biological Activities of Lactose-Derived Prebiotics and Symbiotic with Probiotics on Gastrointestinal System

Lactose-derived prebiotics provide wide ranges of gastrointestinal comforts. In this review article, the probable biochemical mechanisms through which lactose-derived prebiotics offer positive gastrointestinal health are reported along with the up-to-date results of clinical investigations; this might be the first review article of its kind, to the best of our knowledge. Lactose-derived prebiotics have unique biological and functional values, and they are confirmed as ‘safe’ by the Food and Drug Administration federal agency. Medical practitioners frequently recommend them as therapeutics as a pure form or combined with dairy-based products (yoghurt, milk and infant formulas) or fruit juices. The biological activities of lactose-derived prebiotics are expressed in the presence of gut microflora, mainly probiotics (Lactobacillus spp. in the small intestine and Bifidobacterium spp. in the large intestine). Clinical investigations reveal that galacto-oligosaccharide reduces the risks of several types of diarrhea (traveler’s diarrhea, osmotic diarrhea and Clostridium difficile associated relapsing diarrhea). Lactulose and lactosucrose prevent inflammatory bowel diseases (Crohn’s disease and ulcerative colitis). Lactulose and lactitol reduce the risk of hepatic encephalopathy. Furthermore, lactulose, galacto-oligosaccharide and lactitol prevent constipation in individuals of all ages. It is expected that the present review article will receive great attention from medical practitioners and food technologists.

Novel Indole-fused benzo-oxazepines (IFBOs) inhibit invasion of hepatocellular carcinoma by targeting IL-6 mediated JAK2/STAT3 oncogenic signals

Inspired by the well-documented tumor protecting ability of paullones, recently, we synthesized novel paullone-like scaffolds, indole-fused benzo-oxazepines (IFBOs), and screened them against hepatocellular carcinoma (HCC) specific Hep-G2 cells. Three of the synthesized compounds significantly attenuated the progression of HCC in vitro. By computational studies, we further discovered that IFBOs exhibited a stable binding complex with the IL-6 receptor. In this context, we investigated in vivo study using the nitrosodiethyl amine (NDEA)-induced HCC model, which strengthened our previous findings by showing the blockade of the IL-6 mediated JAK2/STAT3 oncogenic signaling pathway. Treatment with IFBOs showed remarkable attenuation of cellular proliferation, as evidenced through a decrease in the number of nodules, restoration of body weight, oxidative stress parameters, liver marker enzymes and histological architecture. Interestingly, using a metabolomic approach we further discovered that IFBOs can restore the perturbed metabolic profile associated with the HCC condition to normalcy. Particularly, the efficacy of compound 6a for an anti-HCC response was significantly better than the marketed chemotherapeutic drug, 5-fluorouracil. Altogether, these remarkable findings open up possibilities of developing IFBOs as novel future candidate molecules for plausible alternatives for HCC treatment.