Role of ammonia and inflammation in minimal hepatic encephalopathy

Sex differences in the mediating role of brain-derived neurotrophic factor between inflammation and memory in cirrhotic patients with minimal hepatic encephalopathy

Minimal hepatic encephalopathy (MHE) affects attention, visuo-motor coordination, and visual perception, with mixed evidence on its impact on memory. Brain-derived neurotrophic factor (BDNF) is associated with memory dysfunction, and plays a crucial role in modulating neuroplasticity. This study investigates the mediating role of BDNF in the relationship between pro-inflammatory cytokines (IL-6, IL-15, IL-18), and declarative memory performance, and the moderating effects of sex. Sixty-eight cirrhotic patients and 22 healthy volunteers performed the Psychometric Hepatic Encephalopathy Score for MHE diagnosis and logical memory subtest (Wechsler Memory Scale-III). Moderated mediation analysis using bias-corrected bootstrapping and multiple regression was performed. Results showed that increased levels of IL-18 and IL-15 were significantly associated with lower BDNF levels (p = 0.03 and p = 0.02 respectively). However, no direct effect was observed between IL-18 and IL-15 and memory. The conditional effects of BDNF on memory were significant only for women with and without MHE, and lower BDNF levels were associated with lower memory performance (without MHE: p = 0.002; MHE: p = 0.001). Moreover, BDNF mediated indirectly the relationship between pro-inflammatory cytokines and memory. IL-18 and IL-15 impacted memory through reduced BDNF levels only in women with and without MHE, whereas IL-6 showed no significant effect on BDNF or memory across groups. These findings underscore the important role of BDNF in memory in cirrhotic patients, especially women with MHE, by mediating the IL-18 and IL-15 effects. The study highlights the role of IL-18 and IL-15 cytokines in neuroplasticity-related memory decline, positioning BDNF as a key biomarker for inflammation-associated cognitive impairment in this population.

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.

Hepatic encephalopathy in cirrhosis: therapies and developments

Hepatic encephalopathy (HE) is a frequent decompensation in patients with cirrhosis, which significantly affects morbidity and mortality. Ammonia is a major neurotoxin implicated in the pathogenesis, progression, and severity of HE, and various organs including the gut, muscle, kidney, and brain are involved in its metabolism. Therefore, therapeutic management involves reducing ammonia production and increasing its elimination from the blood and the brain. Prevention of HE in patients at high risk of first and recurrent episodes is important for prolonging survival. Various anti-ammonia therapies with synergistic and complementary actions have been attempted for overt HE and for prophylaxis of the first and recurrent episodes of HE. In the current review, we summarize the currently used and under-development pharmacotherapies/procedure(s) for HE in cirrhosis and their mechanism of action. Primary and secondary prophylaxis with monotherapies and combination therapies are also discussed.

Current Therapeutic Landscape for Metabolic Dysfunction-Associated Steatohepatitis

In recent years, "metabolic dysfunction-associated steatotic liver disease" (MASLD) has been proposed to better connect liver disease to metabolic dysfunction, which is the most common chronic liver disease worldwide. MASLD affects more than 30% of individuals globally, and it is diagnosed by the combination of hepatic steatosis and obesity, type 2 diabetes, or two metabolic risk factors. MASLD begins with the buildup of extra fat, often greater than 5%, within the liver, causing liver hepatocytes to become stressed. This can proceed to a more severe form, metabolic dysfunction-associated steatohepatitis (MASH), in 20-30% of people, where inflammation in the liver causes tissue fibrosis, which limits blood flow over time. As fibrosis worsens, MASH may lead to cirrhosis, liver failure, or even liver cancer. While the pathophysiology of MASLD is not fully known, the current "multiple-hits" concept proposes that dietary and lifestyle factors, metabolic factors, and genetic or epigenetic factors contribute to elevated oxidative stress and inflammation, causing liver fibrosis. This review article provides an overview of the pathogenesis of MASLD and evaluates existing therapies as well as pharmacological drugs that are currently being studied in clinical trials for MASLD or MASH.

Vitamin D Supplementation Is Associated with Inflammation Amelioration and Cognitive Improvement in Decompensated Patients with Cirrhosis

Background/Objectives: Decompensated cirrhosis is characterized by systemic inflammation and innate and adaptive immune dysfunction. Hepatic encephalopathy (HE) is a prevalent and debilitating condition characterized by cognitive disturbances in which ammonia and inflammation play a synergistic pathogenic role. Extraskeletal functions of vitamin D include immunomodulation, and its deficiency has been implicated in immune dysfunction and different forms of cognitive impairment. The aim was to assess changes in cognitive function and inflammation in decompensated patients with cirrhosis receiving vitamin D supplementation. Methods: Patients with cirrhosis discharged from decompensation in two tertiary hospitals in Spain (from September 2017 to January 2020) were assessed before, at 6 and 12 months after vitamin D supplementation. A comprehensive neuropsychological battery and neuroinflammatory markers were examined. In a subgroup of patients, peripheral immune blood cells were analyzed. Results: Thirty-nine patients were recruited. Of those, 27 completed the 6 months evaluation and were analyzed [age 62.4 ± 11.3 years; 22 men; Model for End-Stage Liver Disease (MELD) 11.7 ± 4.0; prior overt HE 33%; median 25-hydroxyvitamin D (25OHD) plasma level 12.7 µgr/L] and 22 achieved 12 months assessment. At baseline, learning and memory (R = 0.382; p = 0.049) and working memory (R = 0.503; p = 0.047) subtests correlated with plasma 25OHD levels. In addition, processing speed (R = -0.42; p = 0.04), attention (R = -0.48; p = 0.04), Tinnetti balance (R = -0.656; p < 0.001) and Tinnetti score (R = -0.659; p < 0.001) were linked to neuroinflammation marker IL-1β. Patients with lower 25OHD had a greater proportion of TH1cells at baseline and a larger amelioration of IL-1β and IL-6 following supplementation. An improvement in working memory was found after 25OHD replacement (46.7 ± 13 to 50 ± 11; p = 0.047). Conclusions: This study supports that vitamin D supplementation modulates low-grade inflammation in decompensated cirrhosis providing cognitive benefits, particularly in working memory.

Clinical Implications of Inflammation in Patients With Cirrhosis

Cirrhosis-associated immune dysfunction refers to the concurrent systemic inflammation and immunoparesis evident across the disease spectrum of chronic liver disease, ranging from the low-grade inflammatory plasma milieu that accompanies compensated disease to the intense high-grade inflammatory state with coexistent severe immune paralysis that defines acute decompensation and acute-on-chronic liver failure. Systemic inflammation plays a crucial role in the disease course of cirrhosis and is a key driver for acute decompensation and the progression from compensated to decompensated cirrhosis. Severe systemic inflammation is fundamental to the development of organ dysfunction and failure and, in its most extreme form, acute-on-chronic liver failure. Systemic inflammation propagates the development of hepatic encephalopathy and hepatorenal syndrome-acute kidney injury. It may also be involved in the pathogenesis of further complications such as hepatocellular carcinoma and mental illness. Those patients with the most profound systemic inflammation have the worst prognosis. Systemic inflammation exerts its negative clinical effects through a number of mechanisms including nitric oxide-mediated increased splanchnic vasodilation, immunopathology, and metabolic reallocation.

Value of systemic inflammation markers for the detection of minimal and prediction of overt hepatic encephalopathy after TIPS insertion

Development of overt hepatic encephalopathy (oHE) is a particularly feared complication when considering treatment with transjugular intrahepatic portosystemic shunt (TIPS). However, the pathophysiology of HE, in particular after TIPS-insertion, is complex and valid predictors remain scarce. We aimed to investigate whether systemic inflammation markers (SIM) are linked to minimal (mHE) and overt HE (oHE) development before and after TIPS. 62 prospectively recruited patients undergoing TIPS-insertion were included and monitored for oHE occurrence two years thereafter. Patients underwent psychometric testing including the portosystemic encephalopathy syndrome test (PSE), yielding the psychometric hepatic encephalopathy score (PHES), and Animal Naming Test (ANT) before TIPS (baseline) and during structured follow-up 1, 3, 6 and 12 months afterwards. SIM (IL-6, TNF-α and IL-1β) were measured at corresponding timepoints. Patients were predominantly male (64.5%) with a median age of 58 years and MELD of 11. The majority (75.8%) received a TIPS for treatment of refractory ascites. 67.9% presented with mHE before TIPS. No link between the investigated SIM and PHES or ANT at baseline or during any follow-up was documented. 19 (30.6%) patients developed oHE during follow-up. Neither baseline SIM levels nor test results were significantly associated with risk for oHE. We demonstrated a significant decline of all SIM during follow-up, which did not translate to an ameliorated risk for oHE. In patients undergoing TIPS-insertion, the selected SIM have neither a strong link to post-TIPS-oHE development nor to subclinical changes in psychometric tests for mHE.

The burden of hepatic encephalopathy and the use of albumin as a potential treatment

As a potential sequela of cirrhosis, hepatic encephalopathy (HE) significantly impacts the lives of patients and caregivers and places a substantial burden on the healthcare system. With an increasing incidence over time and a cumulative effect on cognition, HE adversely effects quality of life, morbidity and mortality in patients with cirrhosis. HE can range from minimal or covert (MHE/CHE) to overt and symptomatic (OHE). HE has profound impacts on the health and wellbeing of patients and their families and caregivers. Effective treatments could improve the quality of life for all those affected. In this article, we discuss the existing treatments for HE and focus on the potential role of albumin in the treatment of HE. Currently approved therapies for HE (lactulose and rifaximin) are focused on decreasing the formation of ammonia in the gastrointestinal tract. Among the many agents with alternative mechanisms being investigated for treatment of HE, albumin has been studied in clinical trials with acute (≤ 3 days), short-term (up to 2 weeks) prolonged (> 2 weeks) and long-term administration (months). Current studies indicate that acute or short-term administration of albumin does not provide significant benefit for patients with OHE. However, there is increasing evidence that prolonged or long-term albumin therapy can help improve cognition in OHE and prevent recurrence. Additional studies are needed to substantiate these positive findings for longer term administration of albumin in HE and to increase our comprehension of the pharmacologic basis of the effects of albumin.

Infection, inflammation and hepatic encephalopathy from a clinical perspective

Hepatic encephalopathy (HE) is a syndrome that is associated with both acute and chronic liver injury. It manifests as a wide spectrum of neuropsychological abnormalities, ranging from subtle impairments in executive higher functions observed in cirrhosis, through to coma in acute liver failure. In acute liver failure, the central role of ammonia in the development of brain oedema has remained undisputed for 130 years. It latterly became apparent that infection and inflammation were profound determinants for the development of severe hepatic encephalopathy, associated with the development of cerebral oedema and intracranial hypertension. The relationship of the development of hepatic encephalopathy with blood ammonia levels in cirrhosis is less clear cut and the synergistic interplay of inflammation and infection with ammonia has been identified as being fundamental in the development and progression of hepatic encephalopathy. A perturbed gut microbiome and the presence of an impaired gut epithelial barrier that facilitates translocation of bacteria and bacterial degradation products into the systemic circulation, inducing systemic inflammation and innate and adaptive immune dysfunction, has now become the focus of therapies that treat hepatic encephalopathy in cirrhosis, and may explain why the prebiotic lactulose and rifaximin are efficacious. This review summarises the current clinical perspective on the roles of inflammation and infection in hepatic encephalopathy and presents the evidence base for existing therapies and those in development in the setting of acute and chronic liver failure.

Extracellular Vesicles from Mesenchymal Stem Cells Reverse Neuroinflammation and Restore Motor Coordination in Hyperammonemic Rats

Cirrhotic patients may show minimal hepatic encephalopathy (MHE), with mild cognitive impairment and motor deficits. Hyperammonemia and inflammation are the main contributors to the cognitive and motor alterations of MHE. Hyperammonemic rats reproduce these alterations. There are no specific treatments for the neurological alterations of MHE. Extracellular vesicles from mesenchymal stem cells (MSC-EVs) are promising to treat inflammatory and immune diseases. We aimed to assess whether treatment of hyperammonemic rats with MSC-EVs reduced neuroinflammation in cerebellum and restored motor coordination and to study the mechanisms involved. The effects of MSC-EVs were studied in vivo by intravenous injection to hyperammonemic rats and ex vivo in cerebellar slices. Motor coordination was analyzed using the beam walking test. Effects on neuroinflammation were assessed by immunohistochemistry, immunofluorescence and Western blot. Injection of MSC-EVs reduced microglia and astrocytes activation in cerebellum and restored motor coordination in hyperammonemic rats. Ex vivo experiments show that MSC-EVs normalize pro-inflammatory factors, including TNFα, NF-kB activation and the activation of two key pathways leading to motor incoordination (TNFR1-NF-kB-glutaminase-GAT3 and TNFR1-CCL2-BDNF-TrkB-KCC2). TGFβ in the EVs was necessary for these beneficial effects. MSC-EVs treatment reverse neuroinflammation in the cerebellum of hyperammonemic rats and the underlying mechanisms leading to motor incoordination. Therapy with MSC-EVs may be useful to improve motor function in patients with MHE.

Evidence for the Hepato-Retinal Axis: A Systematic Review

BACKGROUND AND OBJECTIVE

Liver health has been reported to be associated with retinal pathology in various ways. These include deposition of retino-toxins, neovascular drive, and disruption of the blood-retina barrier. Extrahepatic synthesis of implicated molecules and hemodynamic changes in liver dysfunction are also considered. The objective was to review the current evidence for and against a hepato-retinal axis that may guide further areas of preclinical and clinical investigation.

METHODS

This was a systematic review. PubMed and Cochrane were queried for English language studies examining the connection between hepatic dysfunction and retinal pathology.

RESULTS

Fourteen studies were included and examined out of 604 candidate publications. The studies selected include preclinical studies as well as clinical case series and studies.

CONCLUSIONS

Several liver pathologies may be linked to retinal pathology as mediated by hepatically synthesized molecules. The hepato-retinal axis may be present and further, targeted studies of the axis are warranted. [Ophthalmic Surg Lasers Imaging Retina 2024;55:587-596.].

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.

Protein-S-100-beta is increased in patients with decompensated cirrhosis admitted to ICU

Background

Hepatic encephalopathy (HE) is highly prevalent in patients with liver diseases. The pathophysiology of HE is centered on the synergic role of hyperammonemia and systemic inflammation. However, some data suggest altered functioning of the blood-brain barrier (BBB). Assessing BBB function is challenging in clinical practice and at the bedside. Protein-S-100 Beta (PS100-Beta) could be a useful peripheral marker of BBB permeability in HE. This study aimed to assess plasmatic PS100-Beta levels in a prospective cohort of patients admitted to the intensive care unit (ICU) with decompensated cirrhosis with and without overt HE.

Methods

We retrospectively evaluated a prospective cohort of cirrhotic patients admitted to the ICU from October 2013 to September 2015 that had an available plasmatic PS100-Beta measurement. Patients with previous neurological impairment or limitation of intensive or resuscitative measures were excluded. Overt HE was defined as West-Haven grades 2 to 4. The patients were compared to a control cohort of outpatient clinic cirrhotic and non-cirrhotic patients explored for isolated elevation of liver enzymes. After ICU discharge, the patients were followed for at least 3 months for the occurrence of overt HE. Adverse outcomes (liver transplantation or death) were collected. The ability of PS100-Beta - in combination with other factors - to predict overt HE was evaluated in a multivariate analysis using logistic regression. Likelihood ratios were used to determine the effects and calculate odds ratios (OR). Survival analysis was performed by using the Kaplan-Meier method and survival between groups was compared using a Log-rank test.

Results

A total of 194 ICU patients and 207 outpatients were included in the study. Increased levels of plasmatic PS100-Beta were detected in the ICU decompensated cirrhotic patients compared with the outpatients ([0.15±0.01] mg/L vs. [0.08±0] mg/L, P <0.001). ICU patients with overt HE had higher levels of PS100-Beta ([0.19±0.03] mg/L) compared with the ICU patients without overt HE ([0.13±0.01] mg/L) (P=0.003). PS100-Beta levels did not differ in outpatients with F 0-3 compared to F 4 fibrosis (P=0.670). PS100-Beta values were correlated with Child-Pugh score (P <0.001), Model for End-Stage Liver Disease (MELD) score (P=0.004), C-reactive protein (P <0.001), ammonemia (P <0.001), and chronic liver failure consortium (CLIF-C) organ failure (P <0.001) and CLIF-C acute-on-chronic (P=0.038) scores, but not with leukocytes (P=0.053), procalcitonin (PCT) (P=0.107), or the lymphocyte-to-neutrophil ratio in ICU patients (P=0.522). In a multivariate model including age, ammonemia, PS100-Beta, PCT, MELD, presence of transjugular portosystemic shunt, and sodium level, the diagnostic performance was 0.765 for the diagnosis of overt HE. Patients with a PS100-Beta level <0.12 mg/L had a better overall survival (P=0.019) and a better survival without liver transplantation (P=0.013).

Conclusions

Serum levels of PS100-Beta are elevated in ICU patients with decompensated cirrhosis, and even more so in those displaying overt HE, and the levels are correlated with outcome. This suggests an increase in the permeability of the BBB in these patients.

Determinants, profile and outcomes of hepatitis A virus-associated severe acute liver injury in adults

BACKGROUND AND OBJECTIVES

Hepatitis A virus (HAV)-related hepatitis is witnessing an epidemiological transition with increasing trends in adults. While uncomplicated hepatitis remains common, evidence suggests it to be a growing cause for acute liver failure (ALF). In between the two extremes exists severe acute liver injury (s-ALI) which has a propensity to transition to ALF. We aimed at describing the clinical profile of patients with HAV-related s-ALI and identifying potential predictors of progression to ALF.

METHODS

This was a single-center retrospective analysis of adult patients admitted with HAV-related s-ALI between April 2022 and December 2023. Demographic and laboratory parameters were compared between patients with only s-ALI and those with ALF. Predictors of progression from s-ALI to ALF were identified using logistic regression.

RESULTS

Forty-three patients satisfied criteria of s-ALI, of which 33 (76.7%) had only s-ALI, while 10 (23.3%) had ALF. Patients with s-ALI had lesser leukocytosis (6.3 ± 3 vs. 13.2 ± 4.8), less incidence of acute kidney injury (9.1% vs. 40%) and lower model for end-stage liver disease (MELD) (20 [18-24.5] vs. 31.5 [26-42]), arterial lactate (2.1 [1.3-3.1] vs. 6.3 [5.2-8.0]), arterial ammonia (94 [72-118] vs. 299 [188-573]), procalcitonin (0.5 [0.28-1.25] vs. 3.2 [1.2-6.1]) and ferritin (482 [213-1633] vs. 5186 [1341-11,053]) compared to HAV-ALF (p < 0.05 for all). Three patients (9.09%) with s-ALI progressed to ALF of whom one (3%) died. Baseline ammonia levels (unadjusted odds ratio [OR] 1.03 [1.01-1.06]) and leukocyte count (OR 1.00 [1.00-1.01]) tended to be associated with ALF progression, although none was significant after multi-variable adjustment. Ammonia levels had an area under receiver operating curve of 0.816 (0.64-0.93) (p = 0.009) (cut-off of 144 μmol/L). Additional comorbidities did not impact overall outcomes.

CONCLUSION

HAV presents as s-ALI in young adults, with almost one in 10 progressing to ALF. Baseline ammonia may be an important predictor of progression even in s-ALI, but mandates larger well-designed studies.

Hepatic encephalopathy: From novel pathogenesis mechanism to emerging treatments

Hepatic encephalopathy (HE) is one of the major complications of liver disease and significantly affects the quality of life (QOL) of patients. HE is common and frequently relapses in cirrhotic patients. The management of HE is supportive, and precipitating conditions should be eliminated. Most drugs used to treat HE are conventional and include nonabsorbable disaccharides such as lactulose, and antibiotics such as rifaximin. However, their therapeutic efficacy is still suboptimal, and novel therapeutic agents are urgently needed. In addition, the optimal management and diagnosis of minimal HE/covert HE are under debate. In this review, we focus on novel pathogenetic mechanisms such as central nervous system clearance, and emerging therapeutic targets of HE, such as fecal material transplantation. We also discuss different classifications and etiologies of HE.

Contribution of extracellular vesicles to neuroinflammation and cognitive and motor deficits in hyperammonemia and hepatic encephalopathy

Cirrhotic patients can present hepatic encephalopathy (HE), showing motor and cognitive deficits. Hyperammonemia and peripheral inflammation are known to induce neuroinflammation and alter neurotransmission, which finally induces neurological impairment in HE. However, the mechanisms by which the deleterious effects of peripheral inflammation are transmitted to the brain are not well understood. Extracellular vesicles (EVs) have recently emerged as a new mediator between the periphery and the brain, particularly in pathologies associated with sustained inflammation and in neurological disorders. In this work, we summarized the main findings on the role of plasma EVs in hyperammonemia and HE and discussed its potential implication in the pathogenesis of hepatic encephalopathy.

TNF-α blockage by etanercept restores spatial learning and reduces cellular degeneration in the hippocampus during liver cirrhosis

Hepatic encephalopathy (HE) is one of the most debilitating cerebral complications of liver cirrhosis. The one-year survival of patients with liver cirrhosis and severe encephalopathy is less than 50%. Recent studies have indicated that neuroinflammation is a new player in the pathogenesis of HE, which seems to be involved in the development of cognitive impairment. In this study, we demonstrated neurobehavioral and neuropathological consequences of liver cirrhosis and tested the therapeutic potential of the tumor necrosis factor-α (TNF-α) inhibitor, etanercept. Sixty male adult Wistar albino rats (120-190 g) were allocated into four groups, where groups I and IV served as controls. Thioacetamide (TAA; 300 mg/kg) was intraperitoneally injected twice a week for five months to induce liver cirrhosis in group II (n = 20). Both TAA and etanercept (2 mg/kg) were administered to group III (n = 20). At the end of the experiment, spatial learning was assessed using Morris water maze. TNF-α was detected in both serum and hippocampus. The excised brains were also immunohistochemically stained with glial fibrillary acidic protein (GFAP) to estimate both the number and integrity of hippocampal astrocytes. Ultrastructural changes in the hippocampus were characterized by transmission electron microscopy. The results showed that blocking TNF-α by etanercept was accompanied by a lower TNF-α expression and a higher number of GFAP-positive astrocytes in the hippocampus. Etanercept intervention alleviated the neuronal and glial degenerative changes and impeded the deterioration of spatial learning ability. In conclusion, TNF-α is strongly involved in the development of liver cirrhosis and the associated encephalopathy. TNF-α blockers may be a promising approach for management of hepatic cirrhosis and its cerebral complications.

Review article: Emerging and current management of acute-on-chronic liver failure

BACKGROUND

Acute-on-chronic liver failure (ACLF) is a clinically and pathophysiologically distinct condition from acutely decompensated cirrhosis and is characterised by systemic inflammation, extrahepatic organ failure, and high short-term mortality.

AIMS

To provide a narrative review of the diagnostic criteria, prognosis, epidemiology, and general management principles of ACLF. Four specific interventions that are explored in detail are intravenous albumin, extracorporeal liver assist devices, granulocyte-colony stimulating factor, and liver transplantation.

METHODS

We searched PubMed and Cochrane databases for articles published up to July 2023.

RESULTS

Approximately 35% of hospital inpatients with decompensated cirrhosis have ACLF. There is significant heterogeneity in the criteria used to diagnose ACLF; different definitions identify different phenotypes with varying mortality. Criteria established by the European Association for the Study of the Liver were developed in prospective patient cohorts and are, to-date, the most well validated internationally. Systemic haemodynamic instability, renal dysfunction, coagulopathy, neurological dysfunction, and respiratory failure are key considerations when managing ACLF in the intensive care unit. Apart from liver transplantation, there are no accepted evidence-based treatments for ACLF, but several different approaches are under investigation.

CONCLUSION

The recognition of ACLF as a distinct entity from acutely decompensated cirrhosis has allowed for better patient stratification in clinical settings, facilitating earlier engagement with the intensive care unit and liver transplantation teams. Research priorities over the next decade should focus on exploring novel treatment strategies with a particular focus on which, when, and how patients with ACLF should be treated.

Anti-inflammatory strategies for hepatic encephalopathy: preclinical studies

Hepatic encephalopathy (HE) is a potentially reversible neuropsychiatric syndrome. Often, HE causes cognitive and motor dysfunctions due to an acute or chronic insufficiency of the liver or a shunting between the hepatic portal vein and systemic vasculature. Liver damage induces peripheral changes, such as in the metabolism and peripheral inflammatory responses that trigger exacerbated neuroinflammation. In experimental models, anti-inflammatory strategies have demonstrated neuroprotective effects, leading to a reduction in HE-related cognitive and motor impairments. In this scenario, a growing body of evidence has shown that peripheral and central nervous system inflammation are promising preclinical targets. In this review, we performed an overview of FDA-approved drugs and natural compounds which are used in the treatment of other neurological and nonneurological diseases that have played a neuroprotective role in experimental HE, at least in part, through anti-inflammatory mechanisms. Despite the exciting results from animal models, the available data should be critically interpreted, highlighting the importance of translating the findings for clinical essays.

Neutrophil-to-lymphocyte ratio predicts 30-, 90-, and 180-day readmissions of patients with hepatic encephalopathy

Introduction

Hepatic encephalopathy (HE) is a significant complication of cirrhosis, known to be associated with hospital readmission. However, few new serological indicators associated with readmission in HE patients have been identified and reported. The objective of our study was to identify simple and effective predictors reated to readmission in HE patients.

Materials and methods

We conducted a retrospective study at a single center on adult patients admitted with HE from January 2018 to December 2022. The primary endpoint was the first liver-related readmission within 30, 90, and 180 days, and we collected electronic medical records from our hospital for sociodemographic, clinical, and hospitalization characteristics. We utilized logistic regression analysis and multiple linear regression analysis to determine the predictors that were associated with the readmission rate and the length of the first hospitalization.

Results

A total of 424 patients were included in the study, among whom 24 (5.7%), 63 (14.8%), and 92 (21.7%) were readmitted within 30, 90, and 180 days, respectively. Logistic regression analysis showed that insurance status, alcoholic liver disease (ALD), ascites, the model for end-stage liver disease (MELD) score, and neutrophil-to-lymphocyte ratio (NLR) were significantly associated with 30-, 90-, and 180-day readmissions. Age and hepatocellular carcinoma (HCC) were predictors of 90- and 180-day readmissions. ALD was identified as a unique predictor of readmission in men, while hypertension was a predictor of 180-day readmission in women. Variceal bleeding, chronic kidney disease, and MELD score were associated with the length of the first hospitalization.

Conclusions

NLR at discharge was identified as a significant predictor of 30-, 90- and 180-day readmissions in patients with HE. Our findings suggest that incorporating NLR into routine clinical assessments could improve the evaluation of the prognosis of liver cirrhosis.

Gut Microbiota and Antibiotic Treatments for the Main Non-Oncologic Hepato-Biliary-Pancreatic Disorders

The gut microbiota is a pivotal actor in the maintenance of the balance in the complex interconnections of hepato-biliary-pancreatic system. It has both metabolic and immunologic functions, with an influence on the homeostasis of the whole organism and on the pathogenesis of a wide range of diseases, from non-neoplastic ones to tumorigenesis. The continuous bidirectional metabolic communication between gut and hepato-pancreatic district, through bile ducts and portal vein, leads to a continuous interaction with translocated bacteria and their products. Chronic liver disease and pancreatic disorders can lead to reduced intestinal motility, decreased bile acid synthesis and intestinal immune dysfunction, determining a compositional and functional imbalance in gut microbiota (dysbiosis), with potentially harmful consequences on the host's health. The modulation of the gut microbiota by antibiotics represents a pioneering challenge with striking future therapeutic opportunities, even in non-infectious diseases. In this setting, antibiotics are aimed at harmonizing gut microbial function and, sometimes, composition. A more targeted and specific approach should be the goal to pursue in the future, tailoring the treatment according to the type of microbiota modulation to be achieved and using combined strategies.

Integrative analysis of the gut microbiota and faecal and serum short-chain fatty acids and tryptophan metabolites in patients with cirrhosis and hepatic encephalopathy

OBJECTIVE

The purpose of this study was to describe the changes in the gut microbiome of patients with cirrhosis and hepatic encephalopathy (HE), as well as quantify the variations in short-chain fatty acid (SCFA) and tryptophan metabolite levels in serum and faeces.

METHODS

Fresh faeces and serum were collected from 20 healthy volunteers (NC group), 30 cirrhosis patients (Cir group), and 30 HE patients (HE group). Then, 16S rRNA sequencing and metabolite measurements were performed using the faeces. Gas chromatography‒mass spectrometry and ultrahigh-performance liquid chromatography-tandem mass spectrometry were used to measure SCFA and tryptophan levels, respectively. The results were analysed by SIMCA16.0.2 software. Differences in species were identified using MetaStat and t tests. The correlations among the levels of gut microbes and metabolites and clinical parameters were determined using Spearman correlation analysis.

RESULTS

Patients with cirrhosis and HE had lower microbial species richness and diversity in faeces than healthy volunteers; these patients also had altered β-diversity. Serum valeric acid levels were significantly higher in the HE group than in the Cir group. Serum SCFA levels did not differ between the Cir and NC groups. Serum melatonin and 5-HTOL levels were significantly higher in the HE group than in the Cir group. The Cir and NC groups had significant differences in the levels of eight serum tryptophan metabolites. Furthermore, the levels of faecal SCFAs did not differ between the HE and Cir groups. Faecal IAA-Ala levels were significantly lower in the HE group than in the Cir group. There were significant differences in the levels of 6 faecal SCFAs and 7 faecal tryptophan metabolites between the Cir and NC groups. Certain gut microbes were associated with serum and faecal metabolites, and some metabolites were associated with certain clinical parameters.

CONCLUSION

Reduced microbial species richness and diversity were observed in patients with HE and cirrhosis. In both serum and faeces, the levels of different SCFAs and tryptophan metabolites showed varying patterns of change. In HE patients, the levels of some serum tryptophan metabolites, and not SCFAs, were correlated with liver function and systemic inflammation. Systemic inflammation in patients with cirrhosis was correlated with faecal acetic acid levels. In summary, this study identified metabolites important for HE and cirrhosis.

Regulation of mild cognitive impairment associated with liver disease by humoral factors derived from the gastrointestinal tract and MRI research progress: a literature review

Patients with liver disease are prone to various cognitive impairments. It is undeniable that cognitive impairment is often regulated by both the nervous system and the immune system. In this review our research focused on the regulation of mild cognitive impairment associated with liver disease by humoral factors derived from the gastrointestinal tract, and revealed that its mechanisms may be involved with hyperammonemia, neuroinflammation, brain energy and neurotransmitter metabolic disorders, and liver-derived factors. In addition, we share the emerging research progress in magnetic resonance imaging techniques of the brain during mild cognitive impairment associated with liver disease, in order to provide ideas for the prevention and treatment of mild cognitive impairment in liver disease.

S100B Protein but Not 3-Nitrotyrosine Positively Correlates with Plasma Ammonia in Patients with Inherited Hyperammonemias: A New Promising Diagnostic Tool?

Individuals with inherited hyperammonemias often present developmental and intellectual deficiencies which are likely to be exaggerated by hyperammonemia episodes in long-term outcomes. In order to find a new, systemic marker common to the course of congenital hyperammonemias, we decided to measure the plasma level of S100 calcium-binding protein B (S100B), which is associated with cerebral impairment. Further, we analyzed three mechanistically diverged but linked with oxidative-nitrosative stress biochemical parameters: 3-nitrotyrosine (3-NT), a measure of plasma proteins' nitration; advanced oxidation protein products (AOPP), a measure of protein oxidation; and glutathione peroxidase (GPx) activity, a measure of anti-oxidative enzymatic capacity. The plasma biomarkers listed above were determined for the first time in congenital hyperammonemia. Also, the level of pro- and anti-inflammatory mediators (i.e., IL-12, IL-6, IL-8, TNF-α, IL-1β, and IL-10) and chemokines (IP-10, MCP-1, MIG, and RANTES) were quantified. S100B was positively correlated with plasma ammonia level, while noticeable levels of circulating 3-NT in some of the patients' plasma did not correlate with ammonia concentration. Overall, the linear correlation between ammonia and S100B but not standard oxidative stress-related markers offers a unique perspective for the future identification and monitoring of neurological deficits risk-linked with hyperammonemia episodes in patients with inherited hyperammonemias. The S100B measure may support the development of therapeutic targets and clinical monitoring in these disorders.

Evaluation of oxidative damage to biomolecules and inflammation in patients with urea cycle disorders

Urea cycle disorders (UCD) are inborn errors of metabolism that occur due to a loss of function in enzymes and transporters involved in the urea cycle, causing an intoxication by hyperammonemia and accumulation of metabolites. Patients can develop hepatic encephalopathy (HE), severe neurological and motor disabilities, and often death. The mechanisms involved in the pathophysiology of UCD are many and complex, but there are strong indications that oxidative stress and inflammation are present, being responsible for at least part of the cellular damage that occurs in these diseases. The aim of this study was to evaluate oxidative and nitrosative damage and inflammation in UCD, to better understand the pathophysiology mechanisms of these diseases. We evaluated the nitrite and nitrate content, thiobarbituric acid-reactive substances (TBARS), carbonyl protein content and a panel of cytokines in plasma sample of 14 patients. The UCD patients group consisted of individuals affected with ornithine transcarbamylase deficiency (n = 8), carbamoyl phosphate synthetase deficiency (n = 2), argininosuccinate synthetase deficiency (n = 2); arginase 1 deficiency (n = 1) and argininosuccinate lyase deficiency (n = 1). Patients mean age at diagnosis was 5.25 ± 9.86 years-old and mean concentrations were compared with healthy individuals of matched age and gender. We found a significant reduction in nitrogen reactive species in patients when compared to controls. TBARS was increased in patients, indicating lipid peroxidation. To evaluate protein oxidative damage in UCD, the carbonyl content was measured, and the results also demonstrated an increase in this biomarker. Finally, we found that UCD patients have enhanced concentrations of cytokines, with pro-inflammatory interleukins IL-6, IL-8, interferon-γ and TNF-α, and anti-inflammatory IL-10 being increased when compared to the control group. In conclusion, our results demonstrate that oxidative stress and inflammation occurs in UCD and probably contribute to the severe brain damage present in patients.

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.

A double-blind randomized placebo-controlled trial of albumin in outpatients with hepatic encephalopathy: HEAL study

BACKGROUND & AIMS

Even after recovery from overt hepatic encephalopathy (HE), minimal HE (MHE), which impairs quality of life (QoL), can persist. A double-blind, placebo-controlled randomized clinical trial was performed to determine the impact of albumin vs. saline on MHE and QoL in individuals with prior HE already on standard of care.

METHODS

Outpatients with cirrhosis and prior HE, MHE and hypoalbuminemia already on treatment for HE were included. Patients on regular IV albumin infusions were excluded. Participants were randomized 1:1 to receive either weekly infusions of 25% IV albumin 1.5 g/kg or saline over 5 weeks. MHE was defined using either psychometric hepatic encephalopathy score (PHES), Stroop or critical clicker frequency. MHE, QoL (based on sickness impact profile [SIP] total, physical, psychosocial domain) and serum markers (inflammation, endothelial dysfunction, and ischemia-modified albumin) were compared between baseline, the final infusion visit (end-of-drug [EOD]) and 1-week post final infusion (end-of-study [EOS]).

RESULTS

Forty-eight (24/group) participants were randomized and balanced (including by HE medication use) at baseline. Adverse events were similar, with MELD and ammonia remaining stable between/within groups. Albumin levels increased and ischemia-modified albumin decreased only in the albumin group at EOD and EOS vs. baseline. PHES and Stroop MHE reversal and improvement were greater in the albumin group at EOD and persisted at EOS. SIP total and psychosocial, but not physical, domain improved only in the albumin group at EOD and EOS vs. baseline. A significant reduction in IL-1β and endothelial dysfunction markers was also observed in the albumin group.

CONCLUSION

In a double-blind, placebo-controlled trial of outpatients with cirrhosis, prior HE and current MHE, albumin infusions were associated with improved cognitive function and psychosocial QoL, likely due to amelioration of endothelial dysfunction.

CLINICAL TRIALS REGISTRATION

www.

CLINICALTRIALS

gov NCT03585257.

IMPACT AND IMPLICATIONS

Even after recovery from overt hepatic encephalopathy (HE), minimal HE (MHE), which impairs quality of life, can persist. We found that intravenous albumin infusions were associated with improved cognitive function and psychosocial quality of life, likely owing to amelioration of endothelial dysfunction, compared to placebo in outpatients with prior HE and current MHE. In patients who continue to demonstrate cognitive dysfunction and impaired quality of life despite standard of care therapy for HE, albumin infusions could be considered if these results are validated.

Role of gut microbiota in the pathogenesis and therapeutics of minimal hepatic encephalopathy via the gut-liver-brain axis

Minimal hepatic encephalopathy (MHE) is a frequent neurological and psychiatric complication of liver cirrhosis. The precise pathogenesis of MHE is complicated and has yet to be fully elucidated. Studies in cirrhotic patients and experimental animals with MHE have indicated that gut microbiota dysbiosis induces systemic inflammation, hyperammonemia, and endotoxemia, subsequently leading to neuroinflammation in the brain via the gut-liver-brain axis. Related mechanisms initiated by gut microbiota dysbiosis have significant roles in MHE pathogenesis. The currently available therapeutic strategies for MHE in clinical practice, including lactulose, rifaximin, probiotics, synbiotics, and fecal microbiota transplantation, exert their effects mainly by modulating gut microbiota dysbiosis. Microbiome therapies for MHE have shown promised efficacy and safety; however, several controversies and challenges regarding their clinical use deserve to be intensively discussed. We have summarized the latest research findings concerning the roles of gut microbiota dysbiosis in the pathogenesis of MHE via the gut-liver-brain axis as well as the potential mechanisms by which microbiome therapies regulate gut microbiota dysbiosis in MHE patients.

Extracellular vesicles from mesenchymal stem cells reduce neuroinflammation in hippocampus and restore cognitive function in hyperammonemic rats

Chronic hyperammonemia, a main contributor to hepatic encephalopathy (HE), leads to neuroinflammation which alters neurotransmission leading to cognitive impairment. There are no specific treatments for the neurological alterations in HE. Extracellular vesicles (EVs) from mesenchymal stem cells (MSCs) reduce neuroinflammation in some pathological conditions. The aims were to assess if treatment of hyperammonemic rats with EVs from MSCs restores cognitive function and analyze the underlying mechanisms. EVs injected in vivo reach the hippocampus and restore performance of hyperammonemic rats in object location, object recognition, short-term memory in the Y-maze and reference memory in the radial maze. Hyperammonemic rats show reduced TGFβ levels and membrane expression of TGFβ receptors in hippocampus. This leads to microglia activation and reduced Smad7-IkB pathway, which induces NF-κB nuclear translocation in neurons, increasing IL-1β which alters AMPA and NMDA receptors membrane expression, leading to cognitive impairment. These effects are reversed by TGFβ in the EVs from MSCs, which activates TGFβ receptors, reducing microglia activation and NF-κB nuclear translocation in neurons by normalizing the Smad7-IkB pathway. This normalizes IL-1β, AMPA and NMDA receptors membrane expression and, therefore, cognitive function. EVs from MSCs may be useful to improve cognitive function in patients with hyperammonemia and minimal HE.

Green Tea Catechin EGCG Ameliorates Thioacetamide-Induced Hepatic Encephalopathy in Rats via Modulation of the Microbiota-Gut-Liver Axis

SCOPE

Existing research suggests that (-)-epigallocatechin-3-gallate (EGCG), which is a natural tea catechin active substance, can protect against liver injury. However, its mechanism for hepatic encephalopathy (HE) treatment is still unclear. In this study, the role of EGCG in the amelioration of HE rats and the effect on the microbiota-gut-liver axis are mainly analyzed.

METHODS AND RESULTS

Thioacetamide (TAA) is employed to induce the HE model in rats. The results of open field test show that EGCG restores locomotor activity and exploratory behavior. Histological and biochemical results demonstrate that EGCG ameliorates brain and liver damage, decreases the expression of pro-inflammatory cytokines, and increases the activity of antioxidant enzymes. Meanwhile, EGCG modulates the Nrf2 pathway and TLR4/NF-κB pathway to mitigate TAA-induced oxidative stress and inflammatory responses. Immunohistochemistry reveals protection of the intestinal barrier by EGCG upregulating the expression of occludin and zonula occludens-1. Furthermore, serum levels of ammonia and LPS are reduced. 16S rRNA analysis shows that EGCG treatment increases the abundance of beneficial bacteria (e.g., Bifidobacterium, Lactobacillus, and Limosilactobacillus).

CONCLUSION

The above results reveal that EGCG has anti-oxidative stress and anti-inflammatory effects, and ameliorates the condition through the microbiota-gut-liver axis, with potential for the treatment of HE.

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.

ATP-binding cassette transporters expression in rats with cirrhosis and hepatic encephalopathy

BACKGROUND

Pathophysiology of acute encephalopathy in cirrhotic patients is not completely understood. Factors implicated include ammonia, inflammation, various metabolic disorders and drug toxicity. Recent studies have evidenced an increased permeability of the blood-brain barrier (BBB) in models of chronic liver disease and encephalopathy, either to solutes, or to leukocytes. A modification of the expression of BBB ATP-Binding Cassette (ABC) transporters, actively transporting endogenous and exogenous components through the BBB, has been described in models of acute liver failure. We hypothesized that a modification of ABC transporters expression may contribute to drug-induced acute encephalopathy in cirrhosis.

MATERIEL AND METHODS

A rat model of cirrhosis induced by Bile Duct Ligation (BDL) was studied, and compared to a SHAM rat model. Rats were sacrificed and brains studied after decapitation. Genic expression of ABC transporters, including P-gp, BCRP, MRP1, MRP2, MRP4 and MRP5 was evaluated by RT-qPCR on isolated brain microvessels. Encephalopathy was assessed 6 weeks after surgery by a trail suspension test and an Open Field Test.

RESULTS

BDL rats developed a histologically proven cirrhosis and displayed a higher ammonemia than SHAM rats (183 µmol/L vs 53 µmol/L, p = 0.0003). BDL rats presented with encephalopathy shown by neurobehavioral tests. MRP2 was not detected neither in BDL nor in SHAM rats. There was a decrease in the genic expression of MRP5 6 weeks after surgery. Expressions of P-gp, BCRP, MRP1 and MRP4 were not different between the 2 groups.

CONCLUSION

We suggest that acute encephalopathy in cirrhotic BDL rats may be associated to a modification of ABC transporter MRP5 on the BBB, that could be responsible for a decrease clearance of neurotoxic agents.

The Link between Gut Microbiota and Hepatic Encephalopathy

Hepatic encephalopathy (HE) is a serious complication of cirrhosis that causes neuropsychiatric problems, such as cognitive dysfunction and movement disorders. The link between the microbiota and the host plays a key role in the pathogenesis of HE. The link between the gut microbiome and disease can be positively utilized not only in the diagnosis area of HE but also in the treatment area. Probiotics and prebiotics aim to resolve gut dysbiosis and increase beneficial microbial taxa, while fecal microbiota transplantation aims to address gut dysbiosis through transplantation (FMT) of the gut microbiome from healthy donors. Antibiotics, such as rifaximin, aim to improve cognitive function and hyperammonemia by targeting harmful taxa. Current treatment regimens for HE have achieved some success in treatment by targeting the gut microbiota, however, are still accompanied by limitations and problems. A focused approach should be placed on the establishment of personalized trial designs and therapies for the improvement of future care. This narrative review identifies factors negatively influencing the gut-hepatic-brain axis leading to HE in cirrhosis and explores their relationship with the gut microbiome. We also focused on the evaluation of reported clinical studies on the management and improvement of HE patients with a particular focus on microbiome-targeted therapy.

Dysregulation of Astrocytic Glutamine Transport in Acute Hyperammonemic Brain Edema

Acute liver failure (ALF) impairs ammonia clearance from blood, which gives rise to acute hyperammonemia and increased ammonia accumulation in the brain. Since in brain glutamine synthesis is the only route of ammonia detoxification, hyperammonemia is as a rule associated with increased brain glutamine content (glutaminosis) which correlates with and contributes along with ammonia itself to hyperammonemic brain edema-associated with ALF. This review focuses on the effects of hyperammonemia on the two glutamine carriers located in the astrocytic membrane: Slc38a3 (SN1, SNAT3) and Slc7a6 (y + LAT2). We emphasize the contribution of the dysfunction of either of the two carriers to glutaminosis- related aspects of brain edema: retention of osmotically obligated water (Slc38a3) and induction of oxidative/nitrosative stress (Slc7a6). The changes in glutamine transport link glutaminosis- evoked mitochondrial dysfunction to oxidative-nitrosative stress as formulated in the “Trojan Horse” hypothesis.

Albumin therapy for hepatic encephalopathy: current evidence and controversies

Hepatic encephalopathy (HE) is a common complication that occurs in 16-21% of end-stage cirrhosis patients. Emerging evidence suggests that systemic inflammation and oxidative stress may play a role in the development of HE. Recent understanding on the anti-inflammatory properties of human albumin has led to growing interest of using human albumin for the treatment and prevention of HE among decompensated patients. In this review, we aim to discuss the current evidence and controversies of using human albumin for the treatment and prevention of HE in advanced cirrhosis patients.

L-ornithine L-aspartate in acute treatment of severe hepatic encephalopathy: A double-blind randomized controlled trial

BACKGROUND AND AIMS

Data on the use of intravenous L-ornithine L-aspartate (LOLA) in the treatment of overt HE (OHE) is limited. We evaluated the role of intravenous LOLA in patients of cirrhosis with OHE grade III-IV.

APPROACH AND RESULTS

In a double-blind randomized placebo-controlled trial, 140 patients were randomized to a combination of LOLA, lactulose, and rifaximin (n = 70) or placebo, lactulose, and rifaximin (n = 70). LOLA was given as continuous intravenous infusion at a dose of 30 g over 24 h for 5 days. Ammonia levels, TNF-α, ILs, and endotoxins were measured on days 0 and 5. The primary outcome was the improvement in the grade of HE at day 5. Higher rates of improvement in grade of HE (92.5% vs. 66%, p < 0.001), lower time to recovery (2.70 ± 0.46 vs. 3.00 ± 0.87 days, p = 0.03), and lower 28-day mortality (16.4% vs. 41.8%, p = 0.001) were seen in the LOLA group as compared with placebo. Levels of inflammatory markers were reduced in both groups. Significantly higher reductions in levels of blood ammonia, IL-6, and TNF-α were seen in the LOLA group.

CONCLUSIONS

Combination of LOLA with lactulose and rifaximin was more effective than only lactulose and rifaximin in improving grades of HE, recovery time from encephalopathy, with lower 28-day mortality.

Effect of a specific Escherichia coli Nissle 1917 strain on minimal/mild hepatic encephalopathy treatment

BACKGROUND

Hepatic encephalopathy (HE) can be considered a result of dysregulated gut-liver-brain axis function, where cognitive impairment can be reversed or prevented by the beneficial effects induced by "gut-centric" therapies, such as the administration of nonabsorbable disaccharides, nonabsorbable antibiotics, probiotics and prebiotics.

AIM

To assess the short-term efficacy and safety of the probiotic Escherichia coli Nissle (EcN) 1917 strain compared to lactulose and rifaximin in patients with minimal/mild HE.

METHODS

From January 2017 to March 2020, a total of 45 patients with HE were enrolled in this prospective, single-centre, open-label, randomized study. Participants were randomly assigned at a ratio of 1:1:1 to one of the treatment groups: The EcN group (n = 15), lactulose group (n = 15) or rifaximin group (n = 15) for a 1 mo intervention period. The main primary outcomes of the study were changes in serum ammonia and Stroop test score. The secondary outcomes were markers of a chronic systemic inflammatory response (ІL-6, ІL-8, and IFN-γ) and bacteriology of the stool flora evaluated by specialized nonculture techniques after a 1 mo intervention period.

RESULTS

Patients who were given rifaximin or EcN showed a more significant reduction in serum ammonia and normalization of Bifidobacteria and Lactobacilli abundance compared to the lactulose group. However, the most pronounced restoration of the symbiotic microflora was associated with EcN administration and characterized by the absence of E. coli with altered properties and pathogenic enterobacteria in patient faeces. In the primary outcome analysis, improvements in the Stroop test parameters in all intervention groups were observed. Moreover, EcN-treated patients performed 15% faster on the Stroop test than the lactulose group patients (P = 0.017). Both EcN and rifaximin produced similar significant reductions in the proinflammatory cytokines INF-γ, IL-6 and IL-8. EcN was more efficient than lactulose in reducing proinflammatory cytokine levels.

CONCLUSION

The use of the probiotic EcN strain was safe and quite efficient for HE treatment. The probiotic reduced the ammonia content and the level of serum proinflammatory cytokines, normalized the gut microbiota composition and improved the cognitive function of patients with HE. The application of the EcN strain was more effective than lactulose treatment.

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.

New Insights into Stroke Prevention and Treatment: Gut Microbiome

Stroke, a lethal neurological disease, accounts for a grave economic burden on society. Despite extensive basic and clinical studies on stroke prevention, a precise effective treatment approach for stroke at this stage remains unavailable. The majority of our body's gut microbiota plays a vital role in food digestion, immune regulation, and nervous system development, which is highly associated with the development of some diseases. Multiple clinical studies have documented variation in the composition of gut microbiota between stroke patients and healthy counterparts. Moreover, the intervention of intestinal symbiotic microorganisms via several mechanisms plays an active role in stroke prognosis. In the prevention and treatment of stroke, the gut microbiota gives off a seductive glow, this is a promising therapeutic target. This paper summarizes the current knowledge of stroke and gut microbiota, and systematically describes the possible mechanisms of interaction between stroke and gut microbiota, the relationship between stroke-related risk factors and gut microbiota, and the treatment of gut flora using microorganisms. Thus, it could valuably elucidate the correlation of gut microbiota with stroke incidence, providing stroke researchers with a new strategy for stroke prevention and treatment by regulating gut microbiota.

A systemic mechanism of increased transendothelial migration of leukocytes through the blood-brain barrier in hepatic encephalopathy

BACKGROUND

Hepatic encephalopathy (HE) is a frequent neurological complication of cirrhosis. Evidence suggests a synergic pathophysiological implication of hyperammonemia and systemic inflammation. In addition, the blood-brain barrier (BBB) permeability can be impaired in cirrhotic patients, notably in those displaying HE. We hypothesized that systemic inflammation could trigger leukocytes transendothelial migration (TEM) through the BBB in cirrhotic patients and especially those with HE.

METHODS

We studied the effects of patients' plasma on the TEM of the leukocyte U937 cell line in vitro, using a validated BBB model (hCMEC/D3 cell line). We compared TEM of U937 leukocytes across hCMEC/D3 monolayer incubated with the plasma of i) patients with cirrhosis without HE, ii) patients with cirrhosis and HE, iii) healthy controls.

RESULTS

We show that the plasma of cirrhotic patients with HE enhances TEM of U937 leukocytes across hCMEC/D3 BBB model. We found a correlation between U937 TEM on the one hand, the West-Haven score and ammonemia on the other one. A trend towards a correlation between U937 TEM and PS-100Beta in plasma, a marker of BBB solute's permeability increase, was also found.

CONCLUSION

These findings suggest that circulating factors could increase leukocytes TEM in cirrhotic patients and contribute to the increased BBB permeability that has been described in cirrhotic patients with HE.

Metabolomics in the understanding and management of hepatic encephalopathy

Metabolomics refers to the study of biological components below 1000 Daltons (Da) involved in metabolic pathways as substrates, products or effectors. According to the interconnected metabolic disturbances that have been described in the pathophysiology of hepatic encephalopathy (HE), this technique appears to be well adapted to study and better delineate the disease. This review will focus on recent advances in metabolomics in the field of HE. Thus, after a brief overview of the general principles of metabolomics, we will discuss metabolomics as a potentially efficient tool for unraveling new HE pathophysiological insights, biomarkers identification, or as a predicting tool for treatment response or outcome prognosis. Finally, we will give our vision on the prospects offered by metabolomics for improving care of HE patients.

Prognosis and Survival Modelling in Cirrhosis Using Parenclitic Networks

Background: Liver cirrhosis involves multiple organ systems and has a high mortality. A network approach to complex diseases often reveals the collective system behaviours and intrinsic interactions between organ systems. However, mapping the functional connectivity for each individual patient has been challenging due to the lack of suitable analytical methods for assessment of physiological networks. In the present study we applied a parenclitic approach to assess the physiological network of each individual patient from routine clinical/laboratory data available. We aimed to assess the value of the parenclitic networks to predict survival in patients with cirrhosis. Methods: Parenclitic approach creates a network from the perspective of an individual subject in a population. In this study such an approach was used to measure the deviation of each individual patient from the existing network of physiological interactions in a reference population of patients with cirrhosis. 106 patients with cirrhosis were retrospectively enrolled and followed up for 12 months. Network construction and analysis were performed using data from seven clinical/laboratory variables (serum albumin, bilirubin, creatinine, ammonia, sodium, prothrombin time and hepatic encephalopathy) for calculation of parenclitic deviations. Cox regression was used for survival analysis. Result: Initial network analysis indicated that correlation between five clinical/laboratory variables can distinguish between survivors and non-survivors in this cohort. Parenclitic deviations along albumin-bilirubin (Hazard ratio = 1.063, p < 0.05) and albumin-prothrombin time (Hazard ratio = 1.138, p < 0.05) predicted 12-month survival independent of model for end-stage liver disease (MELD). Combination of MELD with the parenclitic measures could predict survival better than MELD alone. Conclusion: The parenclitic network approach can predict survival of patients with cirrhosis and provides pathophysiologic insight on network disruption in chronic liver disease.

Gut Microbes and Hepatic Encephalopathy: From the Old Concepts to New Perspectives

Hepatic encephalopathy (HE) is a severe complication of advanced liver disease and acute liver failure. The clinical spectrum ranges from minor cognitive dysfunctions to lethargy, depressed consciousness, and coma and significantly impact the quality of life, morbidity, and mortality of the patients. It is commonly accepted that the gut milieu is essential for the development of HE; however, despite intensive research efforts, the pathogenesis of HE is still not fully elucidated. As our knowledge of gut microbiota moves from the pioneering era of culture-dependent studies, the connection between microbes, inflammation, and metabolic pathways in the pathogenesis of HE is becoming increasingly clear, providing exciting therapeutic perspectives. This review will critically examine the latest research findings on the role of gut microbes in the pathophysiological pathways underlying HE. Moreover, currently available therapeutic options and novel treatment strategies are discussed.

Cognitive Function, Sarcopenia, and Inflammation Are Strongly Associated with Frailty: A Framingham Cohort Study

BACKGROUND

Frailty is an important contributor to morbidity and mortality in chronic liver disease. Understanding the contributors to frailty has the potential to identify individuals at risk for frailty and may potentially provide targets for frailty-modifying interventions. We evaluated the relationship among cognitive function, inflammation, and sarcopenia and frailty.

METHODS

Using cohorts from the Framingham Heart Study (2011-2014), we evaluated for factors associated with frailty. Exposures included cognitive tests (combined Trails A/B test, Animal Naming Test, and combined Digit Span Forward/Backward test), inflammation (interleukin-6 and tumor necrosis factor receptor II), and sarcopenia (creatinine-to-cystatin C ratio). We performed linear and logistic regression to identify the relationship between these exposures and the Liver Frailty Index (LFI).

RESULTS

The study population (N = 1208) had a median age of 70 years, was 56% female, and 48.5% had evidence of liver disease. The combined Trails A/B test (β 0.05, P < .001), creatinine-to-cystatin C (β -0.17, P = .006), and both inflammatory markers, interleukin-6 levels (β 0.16, P = .002) and tumor necrosis factor receptor II (β 0.21, P = .04), were independently associated with the LFI. Using an LFI cutoff of ≥4.5 to define frailty, Trails A/B (odds ratio [OR] 1.21, 95% confidence interval [CI] 1.07-1.37), Animal Naming Test (OR 0.64, 95% CI 0.42-0.97), sarcopenia (OR 0.10, 95% CI 0.01-0.73), and interleukin-6 (OR 4.99, 95% CI 1.03-15.53) were all associated with frailty. Although liver disease did not modify the relationship between the LFI and the Trails A/B test, interleukin-6 was significantly associated with the LFI only in the presence of liver disease.

CONCLUSIONS

Cognitive performance, inflammation, and sarcopenia, each highly prevalent in cirrhosis, are associated with the LFI in this population-based study of persons without cirrhosis. Further research is warranted for interventions aiming to prevent frailty by tailoring their approach to the patient's underlying risk factors.

The Role of Gut Dysbiosis in Acute-on-Chronic Liver Failure

Acute-on-chronic liver failure (ACLF) is an important syndrome of liver failure that has a high risk of short-term mortality in patients with chronic liver disease. The development of ACLF is associated with proinflammatory precipitating events, such as infection, alcoholic hepatitis, and intense systemic inflammation. Recently, the role of the gut microbiome has increasingly emerged in human health and disease. Additionally, the gut microbiome might have a major role in the development of liver disease. In this review, we examine evidence to support the role of gut dysbiosis in cirrhosis and ACLF. Additionally, we explore the mechanism by which the gut microbiome contributes to the development of ACLF, with a focus on alcohol-induced liver disease.

Hepatic encephalopathy and depression in chronic liver disease: is the common link systemic inflammation?

Hepatic encephalopathy and depression share a number of clinical features, such as cognitive impairment and psychomotor retardation, and are highly prevalent in patients with chronic liver disease. Both conditions signify a poor prognosis, carry an increased mortality and are major determinants of reduced health related quality of life. The pathophysiology of hepatic encephalopathy is complex. Whilst cerebral accumulation of ammonia is well-recognised as being central to the development of hepatic encephalopathy, systemic inflammation, which acts in synergy with hyperammonaemia, is emerging as a key driver in its development. The pro-inflammatory state is also widely documented in depression, and peripheral to brain communication occurs resulting in central inflammation, behavioural changes and depressive symptoms. Gut dysbiosis, with a similar reduction in beneficial bacteria, increase in pathogens and decreased bacterial diversity, has been observed in both hepatic encephalopathy and depression, and it may be that the resultant increased bacterial translocation causes their shared inflammatory pathophysiology. Whilst the literature on a positive association between hepatic encephalopathy and depression in cirrhosis remains to be substantiated, there is evolving evidence that treatment with psychobiotics may be of dual benefit, improving cognition and mood in cirrhosis.