Oxidative stress: a systemic factor implicated in the pathogenesis of hepatic encephalopathy

Therapeutic Effect of Levetiracetam Against Thioacetamide-Induced Hepatic Encephalopathy Through Inhibition of Oxidative Stress and Downregulation of NF-κB, NLRP3, iNOS/NO, Pro-Inflammatory Cytokines and Apoptosis

Hepatic encephalopathy (HE) is a serious brain disorder which associated with neurological and psychiatric manifestations. Oxidative stress and neuroinflammation and apoptosis play main roles in the development of brain damage in HE. Levetiracetam is an antiseizure drug with established antioxidant and anti-inflammatory activities. In the present study we investigated the therapeutic effects of levetiracetam against brain injury in HE and its underlying mechanisms of action. Male C57BL/6 mice were subjected to the induction of HE by the injection of thioacetamide (200 mg/kg) for 2 days. Mice were treated with levetiracetam at two doses (50 or 100 mg/kg/day) for 3 days in the treatment groups. Animals were subjected to a behavioral test and the brain tissues were dissected for histopathological, biochemical, gene expression and immunofluorescence analysis. The results showed that levetiracetam alleviated body weight loss and improved locomotor activity of mice with HE. Levetiracetam treatment decreased the histopathological changes, lipid peroxidation and protein carbonylation while restored the antioxidants (GSH, SOD and CAT) in the brain. Levetiracetam decreased the expression and activity of NF-κB, NOD-like receptor pyrin domain-containing protein 3 (NLRP3) and pro-inflammatory cytokines (TNF-α, IL-1β, IL-6, and IFN-γ) in the brain tissue. Administration of levetiracetam inhibited iNOS/NO pathway and myeloperoxidase (MPO) activity in the brain. Moreover, caspase-3 was decreased and the ratio of Bcl2/Bax was increased in the brain of mice treated with levetiracetam. These findings suggest that levetiracetam may be a promising therapeutic agent for brain injury in HE through inhibiting the oxidative, inflammatory and apoptotic pathways.

Nisin lantibiotic prevents NAFLD liver steatosis and mitochondrial oxidative stress following periodontal disease by abrogating oral, gut and liver dysbiosis

Oral microbiome dysbiosis mediates chronic periodontal disease, gut microbial dysbiosis, and mucosal barrier disfunction that leads to steatohepatitis via the enterohepatic circulation. Improving this dysbiosis towards health may improve liver disease. Treatment with antibiotics and probiotics have been used to modulate the microbial, immunological, and clinical landscape of periodontal disease with some success. The aim of the present investigation was to evaluate the potential for nisin, an antimicrobial peptide produced by Lactococcus lactis, to counteract the periodontitis-associated gut dysbiosis and to modulate the glycolipid-metabolism and inflammation in the liver. Periodontal pathogens, namely Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia and Fusobacterium nucleatum, were administrated topically onto the oral cavity to establish polymicrobial periodontal disease in mice. In the context of disease, nisin treatment significantly shifted the microbiome towards a new composition, commensurate with health while preventing the harmful inflammation in the small intestine concomitant with decreased villi structural integrity, and heightened hepatic exposure to bacteria and lipid and malondialdehyde accumulation in the liver. Validation with RNA Seq analyses, confirmed the significant infection-related alteration of several genes involved in mitochondrial dysregulation, oxidative phosphorylation, and metal/iron binding and their restitution following nisin treatment. In support of these in vivo findings indicating that periodontopathogens induce gastrointestinal and liver distant organ lesions, human autopsy specimens demonstrated a correlation between tooth loss and severity of liver disease. Nisin's ability to shift the gut and liver microbiome towards a new state commensurate with health while mitigating enteritis, represents a novel approach to treating NAFLD-steatohepatitis-associated periodontal disease.

Meld-sarcopenia score and skeletal muscle density predicts short-term readmission of patients with hepatic encephalopathy

PURPOSE

To investigate whether the quality of skeletal muscle mass could predict short-term readmission in patients with hepatic encephalopathy (HE).

METHOD

Patients with HE were enrolled from 2018 to 2022. Sarcopenia and myosteatosis were defined using the L3 skeletal muscle index (SMI) and skeletal muscle density (SMD) obtained from CT imaging. MELD-Sarcopenia score was calculated. Multivariable analysis and multiple linear regression were applied to identify predictors of 30-day readmission and length of hospitalization.

RESULTS

123 patients with HE were included. 55 (44.7%) and 87 (70.7%) patients were identified with sarcopenia and myosteatosis, respectively. Patients with sarcopenia exhibited a higher prevalence of myosteatosis, lower SMI and SMD (p < 0.05). Patients with myosteatosis were older, had a lower body mass index, a higher neutrophil-to-lymphocyte ratio and MELD-sarcopenia scores (p < 0.05). 10 (8.1%) patients were readmitted within 30 days. The readmitted group had a higher MELD-sarcopenia score (25.0 ± 6.6 vs. 19.5 ± 7.8, p = 0.034) and lower L3 SMD (28.3 ± 5.9 vs. 33.8 ± 6.9, p = 0.015). In the multivariable analysis, MELD-sarcopenia score (95% CI 1.388 [1.074-1.793], p = 0.012) and SMD (95% CI 0.778 [0.610-0.991], p = 0.042) were found to be significantly associated with the 30-day readmission of patients with HE. Age (p = 0.028), alcohol liver disease (p = 0.025), and hypertension (p = 0.003) were associated with the length of hospitalization for patients with HE.

CONCLUSIONS

The MELD-sarcopenia score and SMD were identified as predictive factors for short-term readmission in patients diagnosed as HE.

Hepatic encephalopathy complications are diminished by piracetam via the interaction between mitochondrial function, oxidative stress, inflammatory response, and locomotor activity

Background

of the study: Hepatic encephalopathy (HE) is a complication in which brain ammonia (NH4+) levels reach critically high concentrations because of liver failure. HE could lead to a range of neurological complications from locomotor and behavioral disturbances to coma. Several tactics have been established for subsiding blood and brain NH4+. However, there is no precise intervention to mitigate the direct neurological complications of NH4+.

Purpose

It has been found that oxidative stress, mitochondrial damage, and neuro-inflammation play a fundamental role in NH4+ neurotoxicity. Piracetam is a drug used clinically in neurological complications such as stroke and head trauma. Piracetam could significantly diminish oxidative stress and improve brain mitochondrial function.

Research methods

In the current study, piracetam (100 and 500 mg/kg, oral) was used in a mice model of HE induced by thioacetamide (TA, 800 mg/kg, single dose, i.p).

Results

Significant disturbances in animals' locomotor activity, along with increased oxidative stress biomarkers, including reactive oxygen species formation, protein carbonylation, lipid peroxidation, depleted tissue glutathione, and decreased antioxidant capacity, were evident in the brain of TA-treated mice. Meanwhile, mitochondrial permeabilization, mitochondrial depolarization, suppression of dehydrogenases activity, and decreased ATP levels were found in the brain of the TA group. The level of pro-inflammatory cytokines was also significantly high in the brain of HE animals.

Conclusion

It was found that piracetam significantly enhanced mice's locomotor activity, blunted oxidative stress biomarkers, decreased inflammatory cytokines, and improved mitochondrial indices in hyperammonemic mice. These data suggest piracetam as a neuroprotective agent which could be repurposed for the management of HE.

Prognosis after splenectomy plus pericardial devascularization vs transjugular intrahepatic portosystemic shunt for esophagogastric variceal bleeding

BACKGROUND

Portal hypertension combined with esophagogastric variceal bleeding (EGVB) is a serious complication in patients with hepatitis B virus (HBV)-related cirrhosis in China. Splenectomy plus pericardial devascularization (SPD) and transjugular intrahepatic portosystemic shunt (TIPS) are effective treatments for EGVB. However, a comparison of the effectiveness and safety of those methods is lacking.

AIM

To compare the prognosis after SPD vs TIPS for acute EGVB after failure of endoscopic therapy or secondary prophylaxis of variceal rebleeding (VRB) in patients with HBV-related cirrhosis combined with portal hypertension.

METHODS

This retrospective cohort study included 318 patients with HBV-related cirrhosis and EGVB who underwent SPD or TIPS at West China Hospital of Sichuan University during 2009-2013. Propensity score-matched analysis (PSM), the Kaplan-Meier method, and multivariate Cox regression analysis were used to compare overall survival, VRB rate, liver function abnormality rate, and hepatocellular carcinoma (HCC) incidence between the two patient groups.

RESULTS

The median age was 45.0 years (n = 318; 226 (71.1%) males). During a median follow-up duration of 43.0 mo, 18 (11.1%) and 33 (21.2%) patients died in the SPD and TIPS groups, respectively. After PSM, SPD was significantly associated with better overall survival (OS) (P = 0.01), lower rates of abnormal liver function (P < 0.001), and a lower incidence of HCC (P = 0.02) than TIPS. The VRB rate did not differ significantly between the two groups (P = 0.09).

CONCLUSION

Compared with TIPS, SPD is associated with higher postoperative OS rates, lower rates of abnormal liver function and HCC, and better quality of survival as acute EGVB treatment after failed endoscopic therapy or as secondary prophylaxis of VRB in patients with HBV-related cirrhosis combined with portal hypertension. There is no significant between-group difference in VRB rates.

Use of albumin infusion for cirrhosis-related complications: An international position statement

Background & Aims

Numerous studies have evaluated the role of human albumin (HA) in managing various liver cirrhosis-related complications. However, their conclusions remain partially controversial, probably because HA was evaluated in different settings, including indications, patient characteristics, and dosage and duration of therapy.

Methods

Thirty-three investigators from 19 countries with expertise in the management of liver cirrhosis-related complications were invited to organise an International Special Interest Group. A three-round Delphi consensus process was conducted to complete the international position statement on the use of HA for treatment of liver cirrhosis-related complications.

Results

Twelve clinically significant position statements were proposed. Short-term infusion of HA should be recommended for the management of hepatorenal syndrome, large volume paracentesis, and spontaneous bacterial peritonitis in liver cirrhosis. Its effects on the prevention or treatment of other liver cirrhosis-related complications should be further elucidated. Long-term HA administration can be considered in specific settings. Pulmonary oedema should be closely monitored as a potential adverse effect in cirrhotic patients receiving HA infusion.

Conclusions

Based on the currently available evidence, the international position statement suggests the potential benefits of HA for the management of multiple liver cirrhosis-related complications and summarises its safety profile. However, its optimal timing and infusion strategy remain to be further elucidated.

Impact and implications

Thirty-three investigators from 19 countries proposed 12 position statements on the use of human albumin (HA) infusion in liver cirrhosis-related complications. Based on current evidence, short-term HA infusion should be recommended for the management of HRS, LVP, and SBP; whereas, long-term HA administration can be considered in the setting where budget and logistical issues can be resolved. However, pulmonary oedema should be closely monitored in cirrhotic patients who receive HA infusion.

Review article: controversies surrounding the use of carvedilol and other beta blockers in the management of portal hypertension and cirrhosis

BACKGROUND

Advanced chronic liver disease is an increasing cause of premature morbidity and mortality in the UK. Portal hypertension is the primary driver of decompensation, including the development of ascites, hepatic encephalopathy and variceal haemorrhage. Non-selective beta blockers (NSBB) reduce portal pressure and are well established in the prevention of variceal haemorrhage. Carvedilol, a newer NSBB, is more effective at reducing portal pressure due to additional α-adrenergic blockade and has additional anti-oxidant, anti-inflammatory and anti-fibrotic effects.

AIM

To summarise the available evidence on the use of beta blockers, specifically carvedilol, in cirrhosis, focussing on when and why to start METHODS: We performed a comprehensive literature search of PubMed for relevant publications.

RESULTS

International guidelines advise the use of NSBB in primary prophylaxis against variceal haemorrhage in those with high-risk varices, with substantial evidence of efficacy comparable with endoscopic band ligation (EBL). NSBB are also well established in secondary prophylaxis, in combination with EBL. More controversial is their use in patients without large varices, but with clinically significant portal hypertension. However, there is gathering evidence that NSBB, particularly carvedilol, reduce the risk of decompensation and improve survival. While caution is advised in patients with advanced cirrhosis and refractory ascites, recent evidence suggests that NSBB can continue to be used safely, and that premature discontinuation may be detrimental.

CONCLUSIONS

With increasing evidence of benefit independent of variceal bleeding, namely retardation of decompensation and improvement in survival, it is time to consider whether carvedilol should be offered to all patients with advanced chronic liver disease.

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.

Inhibition of Autotaxin Ameliorates LPA-Mediated Neuroinflammation and Alleviates Neurological Dysfunction in Acute Hepatic Encephalopathy

Growing evidence suggests an essential role of neuroinflammation in behavioral abnormalities associated with hepatic encephalopathy (HE). Here, we report the involvement of autotaxin-lysophosphatidic acid (LPA) signaling in HE's pathogenesis. We demonstrate that the autotaxin (ATX) inhibitor PF-8380 attenuates neuroinflammation and improves neurological dysfunction in the mouse model of HE. In the thioacetamide (TAA)-induced model of HE, we found a twofold increase in the levels of ammonia in the brain and in plasma along with a significant change in HE-related behavioral parameters. Mice with HE show an increased brain weight, increased levels of tumor necrosis factor-α (TNF-α), IL-1β (interleukin-1β), interleukin-6 (IL-6), and LPA 18:0 in the cerebral cortex and hippocampus, and increased levels of LPA 18:0 in plasma. Treatment with the autotaxin inhibitor (ATXi) did not affect liver injury, as we observed no change in liver function markers including aspartate aminotransferase (AST), alanine aminotransferase (ALT), and total bilirubin (TBIL) and no change in ammonia levels in the brain and plasma. However, ATXi treatment significantly ameliorated the neuroinflammation, reduced the levels of LPA 18:0 in the cerebral cortex and hippocampus in the brain and plasma, and reduced brain edema and the levels of IL1β, IL-6, and TNF-α. The neurobehavioral symptoms for HE such as the cognitive and motor function deficit and overall clinical grading score were significantly improved in ATXi-treated mice. Mouse astrocytes and microglia stimulated with NH₄CL with or without ATXi showed significant attenuation of oxidative stress and the neuroinflammatory effect of NH4CL in ATXi-treated cells.

Carvedilol attenuates brain damage in mice with hepatic encephalopathy

Brain injury is the most common and serious consequence of hepatic encephalopathy (HE), and its pathophysiology is poorly understood. Excessive inflammatory, oxidative and apoptotic responses are the major mechanisms involved in the progression of brain injury induced by HE. Carvedilol is an adrenergic receptor antagonist with pronouncedantioxidant and anti-inflammatory activity. The present study aimed to investigatethe effects and underlying mechanisms of carvedilol on HE-induced brain damage in mice. Experimental model of HE was induced by the injection of thioacetamide (200 mg/kg) for two consecutive days and then mice were treated with carvedilol (10 or 20 mg/kg/day, orally) for 3 days in treatment groups. After the behavioral test, animals were sacrificed and the brain tissues were collected for biochemical, real time PCR and immunohistochemical analysis. The results showed that carvedilol improved locomotor impairment and reduced mortality rate in mice with HE. Carvedilol treatment decreased the brain levels of oxidative stress markers and induced Nrf2/HO-1 pathway. Carvedilol inhibited the activity of nuclear factor kappa B (NF-κB) and the expression of pro-inflammatory cytokines TNF-α, IL1β and IL-6 in the brain tissues. Treatment of mice with carvedilol caused a significant reduction in the brain levels of iNOS/NO, myeloperoxidase (MPO), cyclooxygenase (COX)-2 and chemokine MCP-1 as proinflammatory mediators in HE. Moreover, the ratio of Bcl2/Bax was increased and apoptotic cell death was decreased in the brain of mice treated with carvedilol. In conclusion, carvedilol exerted protective effect against HE-induced brain injury through increasing antioxidant defense mechanisms and inhibitionof inflammatory and apoptotic pathways.

Protective role of VEGF/VEGFR2 signaling against high fatality associated with hepatic encephalopathy via sustaining mitochondrial bioenergetics functions

Background

The lack of better understanding of the pathophysiology and cellular mechanisms associated with high mortality seen in hepatic encephalopathy (HE), a neurological complication arising from acute hepatic failure, remains a challenging medical issue. Clinical reports showed that the degree of baroreflex dysregulation is related to the severity of HE. Furthermore, mitochondrial dysfunction in the rostral ventrolateral medulla (RVLM), a key component of the baroreflex loop that maintains blood pressure and sympathetic vasomotor tone, is known to underpin impairment of baroreflex. Realizing that in addition to angiogenic and vasculogenic effects, by acting on its key receptor (VEGFR2), vascular endothelial growth factor (VEGF) elicits neuroprotection via maintenance of mitochondrial function, the guiding hypothesis of the present study is that the VEGF/VEGFR2 signaling plays a protective role against mitochondrial dysfunction in the RVLM to ameliorate baroreflex dysregulation that underpins the high fatality associated with HE.

Methods

Physiological, pharmacological and biochemical investigations were carried out in proof-of-concept experiments using an in vitro model of HE that involved incubation of cultured mouse hippocampal neurons with ammonium chloride. This was followed by corroboratory experiments employing a mouse model of HE, in which adult male C57BL/6 mice and VEGFR2 wild-type and heterozygous mice received an intraperitoneal injection of azoxymethane, a toxin used to induce acute hepatic failure.

Results

We demonstrated that VEGFR2 is present in cultured neurons, and observed that whereas recombinant VEGF protein maintained cell viability, gene-knockdown of vegfr2 enhanced the reduction of cell viability in our in vitro model of HE. In our in vivo model of HE, we found that VEGFR2 heterozygous mice exhibited shorter survival rate and time when compared to wild-type mice. In C57BL/6 mice, there was a progressive reduction in VEGFR2 mRNA and protein expression, mitochondrial membrane potential and ATP levels, alongside augmentation of apoptotic cell death in the RVLM, accompanied by a decrease in baroreflex-mediated sympathetic vasomotor tone and hypotension. Immunoneutralization of VEGF exacerbated all those biochemical and physiological events.

Conclusions

Our results suggest that, acting via VEGFR2, the endogenous VEGF plays a protective role against high fatality associated with HE by amelioration of the dysregulated baroreflex-mediated sympathetic vasomotor tone through sustaining mitochondrial bioenergetics functions and eliciting antiapoptotic action in the RVLM.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-022-00831-0.

Sex is associated with differences in oxidative stress and susceptibility to severe hepatic encephalopathy in bile-duct ligated rats

Hepatic encephalopathy (HE) is a debilitating neurological complication of chronic liver disease (CLD). Hyperammonemia plays an important role in HE's pathogenesis, acting synergistically with systemic oxidative stress. During CLD, muscle plays a compensatory role in detoxifying ammonia, and therefore muscle loss leads to an increase in the risk of developing HE. With most animal studies involving males, sex's impact on the development of CLD and associated complications such as HE and muscle loss remains unknown. Therefore, we aimed to identify the impact of sex on CLD, HE, and muscle mass loss in a rodent model of CLD. Liver injury markers, hyperammonemia, oxidative stress, muscle mass and ammonia clearance were measured in female and male bile-duct ligated (BDL) rats. In addition, covert HE was assessed in females while ammonia-precipitated severe HE was assessed in female and male BDL rats, and male BDL rats treated with allopurinol (100mg/kg), an antioxidant (xanthine oxidase inhibitor). Female BDL developed CLD and HE (impaired motor-coordination and night activity) compared to respective SHAM. Hyperammonemia and muscle ammonia clearance were similar between female and male BDL. However, only female BDL rats did not develop muscle loss, brain edema, and short-term memory impairment (vs. female SHAM) and systemic oxidative stress and decreased albumin levels (vs. male BDL). Furthermore, both female BDL and allopurinol-treated male BDL rats were protected against ammonia-induced overt HE. In conclusion, female and male BDL rats develop distinct features of CLD and HE, with systemic oxidative stress playing a pivotal role in the susceptibility to ammonia precipitated overt HE.

Overview of oxidative stress findings in hepatic encephalopathy: From cellular and ammonium-based animal models to human data

Oxidative stress is a natural phenomenon in the body. Under physiological conditions intracellular reactive oxygen species (ROS) are normal components of signal transduction cascades, and their levels are maintained by a complex antioxidants systems participating in the in-vivo redox homeostasis. Increased oxidative stress is present in several chronic diseases and interferes with phagocytic and nervous cell functions, causing an up-regulation of cytokines and inflammation. Hepatic encephalopathy (HE) occurs in both acute liver failure (ALF) and chronic liver disease. Increased blood and brain ammonium has been considered as an important factor in pathogenesis of HE and has been associated with inflammation, neurotoxicity, and oxidative stress. The relationship between ROS and the pathophysiology of HE is still poorly understood. Therefore, sensing ROS production for a better understanding of the relationship between oxidative stress and functional outcome in HE pathophysiology is critical for determining the disease mechanisms, as well as to improve the management of patients. This review is emphasizing the important role of oxidative stress in HE development and documents the changes occurring as a consequence of oxidative stress augmentation based on cellular and ammonium-based animal models to human data.

An evaluation on potential anti-oxidant and anti-inflammatory effects of Crocin

Crocin, an active ingredient derived from saffron, is one of the herbal components that has recently been considered by researchers. Crocin has been shown to have many anti-inflammatory and antioxidant properties, and therefore can be used to treat various diseases. It has been shown that Crocin has a positive effect on the prevention and treatment of cardiovascular disease, cancer, diabetes, and kidney disease. In addition, the role of this substance in COVID-19 pandemic has been identified. In this review article, we tried to have a comprehensive review of the antioxidant and anti-inflammatory effects of Crocin in different diseases and different tissues. In conclusion, Crocin may be helpful in pathological conditions that are associated with inflammation and oxidative stress.

Thymol ameliorated neurotoxicity and cognitive deterioration in a thioacetamide-induced hepatic encephalopathy rat model; involvement of the BDNF/CREB signaling pathway

In the present study, we aimed to delineate the neuroprotective potential of thymol (THY) against neurotoxicity and cognitive deterioration induced by thioacetamide (TAA) in an experimental model of hepatic encephalopathy (HE). Rats received TAA (100 mg kg^-1, intraperitoneally injected, three times per week) for two weeks. THY (30 and 60 mg kg^-1), and Vit E (100 mg k^-1) were administered daily by oral gavage for 30 days after HE induction. Supplementation with THY significantly improved liver function, reduced serum ammonia level, and ameliorated the locomotor and cognitive deficits. THY effectively modulated the alteration in oxidative stress markers, neurotransmitters, and brain ATP content. Histopathology of liver and brain tissues showed that THY had ameliorated TAA-induced damage, astrocyte swelling and brain edema. Furthermore, THY downregulated NF-kB and upregulated GFAP protein expression. In addition, THY significantly promoted CREB and BDNF expression at both mRNA and protein levels, together with enhancing brain cAMP level. In conclusion, THY exerted hepato- and neuroprotective effects against HE by mitigating hepatotoxicity, hyperammonemia and brain ATP depletion via its antioxidant, anti-inflammatory effects in addition to activation of the CREB/BDNF signaling pathway.

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.

PET CMRglc mapping and 1H-MRS show altered glucose uptake and neurometabolic profiles in BDL rats

Type C hepatic encephalopathy (HE) is a complex neuropsychiatric disorder occurring as a consequence of chronic liver disease. Alterations in energy metabolism have been suggested in type C HE, but in vivo studies on this matter remain sparse and have reported conflicting results. Here, we propose a novel preclinical ¹⁸F-FDG PET methodology to compute quantitative 3D maps of the regional cerebral metabolic rate of glucose (CMR_glc) from a labelling steady-state PET image of the brain and an image-derived input function. This quantitative approach shows its strength when comparing groups of animals with divergent physiology, such as HE animals. PET CMR_glc maps were registered to an atlas and the mean CMR_glc from the hippocampus and the cerebellum were associated to the corresponding localized ¹H-MR spectroscopy acquisitions. This study provides for the first time local and quantitative information on both brain glucose uptake and neurometabolic profile alterations in a rat model of type C HE. A 2-fold lower brain glucose uptake, concomitant with an increase in brain glutamine and a decrease in the main osmolytes was observed in the hippocampus and in the cerebellum. These novel findings are an important step towards new insights into energy metabolism in the pathophysiology of HE.

Central nervous system and systemic oxidative stress interplay with inflammation in a bile duct ligation rat model of type C hepatic encephalopathy

The role and coexistence of oxidative stress (OS) and inflammation in type C hepatic encephalopathy (C HE) is a subject of intense debate. Under normal conditions the physiological levels of intracellular reactive oxygen species are controlled by the counteracting antioxidant response to maintain redox homeostasis. Our previous in-vivo¹H-MRS studies revealed the longitudinal impairment of the antioxidant system (ascorbate) in a bile-duct ligation (BDL) rat model of type C HE. Therefore, the aim of this work was to examine the course of central nervous system (CNS) OS and systemic OS, as well as to check for their co-existence with inflammation in the BDL rat model of type C HE. To this end, we implemented a multidisciplinary approach, including ex-vivo and in-vitro electron paramagnetic resonance spectroscopy (EPR) spin-trapping, which was combined with UV-Vis spectroscopy, and histological assessments. We hypothesized that OS and inflammation act synergistically in the pathophysiology of type C HE. Our findings point to an increased CNS- and systemic-OS and inflammation over the course of type C HE progression. In particular, an increase in the CNS OS was observed as early as 2-weeks post-BDL, while the systemic OS became significant at week 6 post-BDL. The CNS EPR measurements were further validated by a substantial accumulation of 8-Oxo-2'-deoxyguanosine (Oxo-8-dG), a marker of oxidative DNA/RNA modifications on immunohistochemistry (IHC). Using IHC, we also detected increased synthesis of antioxidants, glutathione peroxidase 1 (GPX-1) and superoxide dismutases (i.e.Cu/ZnSOD (SOD1) and MnSOD (SOD2)), along with proinflammatory cytokine interleukin-6 (IL-6) in the brains of BDL rats. The presence of systemic inflammation was observed already at 2-weeks post-surgery. Thus, these results suggest that CNS OS is an early event in type C HE rat model, which seems to precede systemic OS. Finally, our results suggest that the increase in CNS OS is due to enhanced formation of intra- and extra-cellular ROS rather than due to reduced antioxidant capacity, and that OS in parallel with inflammation plays a significant role in type C HE.

Hepatitis C Virus-Related Central and Peripheral Nervous System Disorders

Hepatitis C Virus (HCV), despite being a hepatotropic virus, is the causative agent of many systemic disorders, such as vasculitis, autoimmune diseases, lymphoproliferative disorders, and a broad spectrum of neurological and psychiatric manifestations. Although symptoms have been misdiagnosed or underdiagnosed, only recently, evidence of direct (inflammatory) or indirect (immune-mediated) HCV-dependent cerebral effects has been established. HCV infection can promote acute inflammatory response, pro-coagulative status and ischemic disorders, and neurodegeneration. These effects rely on cerebral HCV replication, possibly mediated by blood-brain barrier alterations. Further study is needed to better understand the HCV-related mechanisms of brain damage.

2021 ISHEN guidelines on animal models of hepatic encephalopathy

This working group of the International Society of Hepatic Encephalopathy and Nitrogen Metabolism (ISHEN) was commissioned to summarize and update current efforts in the development and characterization of animal models of hepatic encephalopathy (HE). As defined in humans, HE in animal models is based on the underlying degree and severity of liver pathology. Although hyperammonemia remains the key focus in the pathogenesis of HE, other factors associated with HE have been identified, together with recommended animal models, to help explore the pathogenesis and pathophysiological mechanisms of HE. While numerous methods to induce liver failure and disease exist, less have been characterized with neurological and neurobehavioural impairments. Moreover, there still remains a paucity of adequate animal models of Type C HE induced by alcohol, viruses and non-alcoholic fatty liver disease; the most common etiologies of chronic liver disease.

Efficacy and safety of albumin infusion for overt hepatic encephalopathy: A systematic review and meta-analysis

BACKGROUND AND AIMS

The efficacy and safety of albumin infusion for treatment and prevention of overt hepatic encephalopathy (OHE) among cirrhosis patients remained controversial. We performed a systematic review and meta-analysis to evaluate the benefit of albumin infusion for the treatment and prevention of OHE.

METHODS

We performed a systematic search of 4 electronic databases up to 31st January 2021. The primary outcome was the resolution of OHE. Secondary outcomes were inpatient mortality and albumin-associated adverse events. We assessed the pooled odds' risk, pooled mean differences, 95% confidence interval and heterogeneity using Review Manager Version 5.3.

RESULTS

A total of 12 studies (2,087 subjects) were identified. Among cirrhosis patients with OHE, albumin infusion was associated with a lower pooled risk of OHE (OR=0.43, 95%CI: 0.27, 0.68; I²=0%). Among patients without baseline OHE, albumin infusion was associated with a lower pooled risk of developing OHE (OR=0.53, 95%CI: 0.32, 0.86; I²=62%). Albumin infusion was associated with a lower pooled risk of inpatient mortality (OR=0.36, 95%CI: 0.21, 0.60; I²=0%).

CONCLUSION

Well-powered randomized trials are required to confirm the benefits of albumin infusion for the prevention and treatment of overt hepatic encephalopathy among decompensated cirrhosis patients.

Development and Validation of a Clinical-Genetic Risk Score to Predict Hepatic Encephalopathy in Patients With Liver Cirrhosis

INTRODUCTION

We aimed to define the impact of the genetic background on overt hepatic encephalopathy (HE) in patients with liver cirrhosis by developing a combined clinical-genetic risk score.

METHODS

Patients suffering from liver cirrhosis from the outpatient clinics of 4 hospitals (n = 600) were included and followed up for at least 5 years until HE bouts, liver transplant, or death. Patients were genotyped for 60 candidate single nucleotide polymorphisms together with the microsatellite in the promoter region of the gene GLS.

RESULTS

Single nucleotide polymorphisms rs601338 (FUT2), rs5743836 (TRL9), rs2562582 (SLC1A3), rs313853 (SLC1A5), and GLS microsatellite did predict independently the incidence and severity of overt HE and were included as genetic score. Competing risk analysis revealed that bilirubin (subhazard ratio [sHR] 1.30 [1.15-1.48], P < 0.001), albumin (sHR 0.90 [0.86-0.93], P < 0.001), genetic score (sHR 1.90 [1.57-2.30], P < 0.001), and previous episodes of overt HE (sHR 2.60 [1.57-4.29], P < 0.001) were independently associated to HE bouts during the follow-up with an internal (C-index 0.83) and external validation (C-index 0.74). Patients in the low-risk group had 5% and 12% risk of HE at 1 (log-rank 92.1; P < 0.001) and 5 (log-rank 124.1; P < 0.001) years, respectively, whereas 36% and 48% in the high-risk group.

DISCUSSION

The genetic background influenced overt HE risk and severity. The clinical-genetic HE Risk score, which combined genetic background together with albumin, bilirubin, and previous episodes of overt HE, could be a useful tool to predict overt HE in patients with cirrhosis.

Transcriptional regulation of alcohol induced liver fibrosis in a translational porcine hepatocellular carcinoma model

Hepatocellular carcinoma (HCC) is the 5th most common and 2nd deadliest cancer worldwide. HCC risk factors include alcohol induced liver cirrhosis, which prompts hepatic inflammation, cell necrosis, and fibrosis deposition. As 25% of HCC cases are associated with alcohol induced liver disease, understanding the effects of the cirrhotic liver microenvironment on HCC tumor biology and therapeutic responses are critical. This study utilized the Oncopig Cancer Model-a transgenic pig model that recapitulates human HCC through induced expression of KRAS^G12D and TP53^R167H driver mutations-to investigate the molecular mechanisms underlying alcohol induced liver disease. Oncopigs (n = 5) underwent fibrosis induction via infusion of ethanol and ethiodized oil (1:3 v/v dosed at 0.75 mL/kg) into the hepatic arterial circulation. Eight-weeks post induction, liver tissue samples from fibrotic and age-matched control (n = 5) Oncopigs were collected for histological evaluation and transcriptional profiling. Increased hepatic inflammation and fibrosis was observed in fibrotic Oncopigs via pathological assessment. Transcriptional profiling (RNA-seq) resulted in the identification of 4387 differentially expressed genes between Oncopig fibrotic and control livers. GO term enrichment analysis identified pathway alterations associated with cirrhosis progression in humans, including cell proliferation, angiogenesis, extracellular matrix deposition, and oxidation-reduction. Key alterations include activation of hepatic stellate cells, increased matrix metalloproteinase production, and altered expression of ABC and SLC transporter genes involved in transport of anticancer drugs.These results demonstrate Oncopig liver fibrosis recapitulates transcriptional hallmarks of human cirrhosis, making the Oncopig an ideal model for studying the effects of the cirrhotic liver microenvironment on HCC tumor biology and therapeutic response.

Distinct gut microbial compositional and functional changes associated with impaired inhibitory control in patients with cirrhosis

Most cirrhosis etiologies, such as alcohol, hepatitis C, and obesity, involve behavior that require the loss of inhibitory control. Once cirrhosis develops, patients can also develop cognitive impairment due to minimal hepatic encephalopathy (MHE). Both processes could have distinct imprints on the gut-liver-brain axis. Determine the impact of inhibitory control versus traditional cirrhosis-related cognitive performance on gut microbial composition and function. Outpatients with cirrhosis underwent two tests for MHE: inhibitory control test (MHEICT, computerized associated with response inhibition) and psychometric hepatic encephalopathy score (MHEPHES, paper-pencil HE-specific associated with subcortical impairment) along with stool collection for metagenomics. MHEICT/not, MHEPHES/not, and discordant (positive on one test but negative on the other) were analyzed for demographics, bacterial species, and gut-brain modules (GBM) using multi-variable analyses. Ninety-seven patients [47 (49%) MHEPHES, 76 (78%) MHEICT, 41 discordant] were enrolled. MHEPHES/not: Cirrhosis severity was worse in MHEPHES without differences in alpha/beta diversity on bacterial species or GBMs. Pathobionts (Enterobacteriaceae) and γ-amino-butryic acid (GABA) synthesis GBM were higher in MHEPHES. MHEICT/not: We found similar cirrhosis severity and metagenomic alpha/beta diversity in MHEICT versus not. However, alpha/beta diversity of GBMs were different in MHEICT versus No-MHE patients. Alistipes ihumii, Prevotella copri, and Eubacterium spp. were higher, while Enterococcus spp. were uniquely lower in MHEICT versus no-MHE and discordant comparisons. GBMs belonging to tryptophan, menaquinone, GABA, glutamate, and short-chain fatty acid synthesis were also unique to MHEICT. Gut microbial signature of impaired inhibitory control, which is associated with addictive disorders that can lead to cirrhosis, is distinct from cirrhosis-related cognitive impairment.

Effects of caffeine on brain antioxidant status and mitochondrial respiration in acetaminophen-intoxicated mice

Hepatic encephalopathy is a pathophysiological complication of acute liver failure, which may be triggered by hepatotoxic drugs such as acetaminophen (APAP). Although APAP is safe in therapeutic concentration, APAP overdose may induce neurotoxicity, which is mainly associated with oxidative stress. Caffeine is a compound widely found in numerous natural beverages. However, the neuroprotective effect of caffeine remains unclear during APAP intoxication. The present study aimed to investigate the possible modulatory effects of caffeine on brain after APAP intoxication. Mice received intraperitoneal injections of APAP (250 mg/kg) and/or caffeine (20 mg/kg) and, 4 h after APAP administration, samples of brain and blood were collected for the biochemical analysis. APAP enhanced the transaminase activity levels in plasma, increased oxidative stress biomarkers (lipid peroxidation and reactive oxygen species), promoted an imbalance in endogenous antioxidant system in brain homogenate and increased the mortality. In contrast, APAP did not induce dysfunction of the mitochondrial bioenergetics. Co-treatment with caffeine modulated the biomarkers of oxidative stress as well as antioxidant system in brain. Besides, survival assays demonstrated that caffeine protective effects could be dose- and time-dependent. In addition, caffeine promoted an increase of mitochondrial bioenergetics response in brain by the enhancement of the oxidative phosphorylation, which could promote a better energy supply necessary for brain recovery. In conclusion, caffeine prevented APAP-induced biochemical alterations in brain and reduced lethality in APAP-intoxicated mice, these effects may relate to the preservation of the cellular antioxidant status, and these therapeutic properties could be useful in the treatment of hepatic encephalopathy induced by APAP intoxication.

Flavonoids from Barnebydendron riedelii leaf extract mitigate thioacetamide-induced hepatic encephalopathy in rats: The interplay of NF-κB/IL-6 and Nrf2/HO-1 signaling pathways

Phytochemical investigation of the butanol fraction (BUF) derived from the 70% aqueous methanolic leaf extract of Barnebydendron riedelii led to the isolation of three flavonoid glycosides; kaempferol-3-O-α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside, quercetin-3-O-α-l-rhamnopyranosyl-(1 → 6)-β-d-galactopyranoside and quercetin-3-O-α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside. Docking studies were fulfilled to validate the possible bio-properties of BUF toward nuclear factorkappa B (NF-κB) and nuclear factor erythroid 2-related factor 2 (Nrf2). The protective role of BUF against behavioral, biochemical, molecular, histopathological and immunohistochemical alterations in thioacetamide (TAA)-induced hepatic encephalopathy in rats was investigated. The toxicological studies indicated that BUF was safe up to 2000 mg/kg bw. Prior to TAA intoxication, rats were orally treated with either BUF at multiple doses (70, 140 and 280 mg/kg bw) or lactulose (8 mL/kg bw) for 14 consecutive days. On the 13th and the 14th day, TAA (200 mg/kg bw/day) was intraperitoneally injected. The BUF significantly improved motor impairment, ameliorated cognitive deficits and attenuated TAA-induced hepatotoxicity. Moreover, BUF controlled the inflammatory processes by suppressing the hepatic inflammatory cytokine; interleukin-6 (IL-6) as well as its pro-inflammatory mediator; NF-κB supporting the molecular docking assessment. The brain neurotransmitters; dopamine, serotonin and noradrenaline, as well as ammonia levels were improved in BUF-treated TAA-intoxicated animals in a dose-dependent manner. Furthermore, BUF administration to TAA-intoxicated rats modulated the Nrf2 and heme oxygenase 1 (HO-1) genes expression in liver and brain tissues. The histological evaluation showed that pretreatment of TAA-intoxicated rats with BUF ameliorated the degenerative effects of TAA on liver and brain tissues as well as reduced the activation of cellular apoptotic marker; caspase-3 and glial fibrillary acidic protein (GFAP⁺) astrocytes. In conclusion, the observed hepato-neuroprotective effect of BUF is attributed to its flavonoidal content through its modulatory effects on of NF-κB/IL-6 and Nrf2/HO-1 signaling pathways.

Proteomic analysis of liver in diet-induced Hyperlipidemic mice under Fructus Rosa roxburghii action

Fructus Rosae Roxburghii (FRR) has been considered as edible and medicinal fruit possessing antiatherosclerotic effect, but the mechanism is still unclear. HLP is material basis for AS formation. Under FRR action, TC, TG, LDL, HDL and ASI in serum were regulated to control level. Differentially expressed proteins in liver were analyzed by using TMT labeling and LC-MS/MS for better understanding the effect and molecular mechanism of FRR on diet-induced hyperlipidemic mice. In total, 4460 proteins were quantified, of which 469 proteins showed dramatic changes between each group. According to molecular functions, 25 differentially co-expressed proteins were divided into five categories: substance metabolism, energy transformation and signal transduction, transcription and translation, immune defense. 15 key proteins involved lipids metabolism, which were identified as Cyp7a1, Cyp3a11, Tm7sf2, COAT2, CSAD, RBP3, Lpin1, Dhrs4, Aldh1b1, GK, Acot 4, TSC22D1, PGFS, EHs, GSTM1. This suggested that FRR could maintain metabolic homeostasis by regulating the metabolism of fatty acids, biosynthesis of BAs and steroids, and production of LPOs. 20 oxidative lipids further confirmed their importance regulating lipids metabolism. It's first time potential antiatherosclerotic mechanism of FRR regulating blood lipids was explored from protein level, which is of great significance to explore new drug targets for AS. SIGNIFICANCE: Under the action of FRR juice, the blood lipids in mice were regulated to control level. By TMT proteomic analysis, the effect and molecular mechanism of FRR on diet-induced hyperlipidemic mice were further explored. 25 differentially co-expressed proteins obtained in three diet groups might cooperatively regulate the lipids metabolism and hepatic function of mice, thus maintaining the metabolism homeostasis. By lipidomics analysis, 20 oxidative lipids further confirmed the importance of ω-3 and ω-6 PUFAs in regulating the lipids metabolism. These findings provide an improved understanding for the regulation of FRR on the blood lipids and explores potential metabolic targets for AS prevention.

HIF1a Inhibitor Rescues Acute-on-Chronic Liver Failure

INTRODUCTION AND OBJECTIVES

Hypoxia-inducible factor-1α is critically involved in the pathogenesis of liver diseases. Its inhibitor genistein attenuated D-galactosamine (D-GalN)-induced liver damage. However, the role of genistein in acute-on-chronic liver failure (ACLF) is unclear. The influence of genistein on reactive oxygen species (ROS) and hepatocyte functions were evaluated in a rat model of ACLF.

MATERIAL AND METHODS

Genistein [20mg/ (kg. day)]/coenzyme Q10 [10mg/ (kg. day)]/lipoic acid [20mg/ (kg. day)] was administered via the intra-gastric route daily for 6 weeks as co-treatment to the rats in the experimental groups. Then, 100μg/kg LPS combined with 0.5g/kg D-GalN was injected intraperitoneally to attack the rats.

RESULTS

Genistein significantly attenuated LPS/D-GalN-induced ACLF, characterized by ameliorated gross appearance and microscopic histopathology of liver, reduced AST level in serum, whereas increased levels of ATP, ADP/O, and respiratory control ratio (RCR) in mitochondria. Genistein suppressed necrosis and ROS production.

CONCLUSION

These results suggested that genistein could protect against ACLF through inhibiting cellular ROS production and necrosis, improving RCR, and decreasing permeability transition pores in mitochondrial, which was similar as mitochondrial protective agent coenzyme Q10.

Anxiety in rats with bile duct ligation is associated with activation of JNK3 mitogen-activated protein kinase in the hippocampus

We examine the anxiety-like behaviors in rats with bile duct ligation (BDL), as well as its relationship with the expression of JNK3 and P38 MAPKs in rat hippocampus. Male Wistar rats undergo either sham operation or BDL as a rat model of cirrhotic HE. The anxiety-like behaviors are determined using a light/dark box test two hours befor the surgery on day 1 and on days 7, 14, 21 and 28 of BDL. The gene and protein expression levels of JNK3 and p38 in the hippocampus were examined respectively with qPCR and western blotting methods on day 28 of BDL. The results revealed that anxiety was increased in the cirrhotic HE model rats during 28 days of BDL. The molecular data indicated that the gene expression of Jnk3 and protein levels of JNK3, as well as phospho-JNK3, significantly increased in the hippocampus of the cirrhotic HE model rats compared to the sham control group. However, the results revealed no significant changes in the gene expression and the protein levels of p38 as well as phospho-p38 in the hippocampus of the cirrhotic HE model rats compared to the sham control group. We conclude that the increases in the expression and activation of JNK3 MAPK in the hippocampus may underlie, at least partly, the anxiety-like behaviors in rats with cirrhotic HE.

The effect and mechanism of combination of total paeony glycosides and total ligustici phenolic acids against focal cerebral ischemia

The root of Paeonia lactiflora Pall. (Chishao, CS) and Ligusticum chuanxiong Hort. (Chuanxiong, CX) were widely used as a drug pair in Chinese Medicine, and the combination of CS and CX showed a more significant inhibition on neuronal apoptosis in our previous study. In the present study, total paeony glycosides (TPGs) from CS and total ligustici phenolic acids (TLPAs) from CX were combined to evaluate the synergistic effects against focal cerebral ischemia both in vitro and in vivo. The combination of TPGs and TLPAs at 7:3 had the best anti-oxidative stress and anti-inflammatory effect on OGD-induced HUVEC. Additionally, the infarction area proportion and neuron apoptosis of rats by TPGs:TLPAs (7:3) was significantly lower than their alone in MCAO rats. Moreover, TPGs: TLPAs of 7:3 showed a more significant effect on decreasing the expression of MMP-2 and MMP-9, and increasing the protein expression or mRNA level of TIMP-1 than other combinations. The optimal ratio of TPGs and TLPAs at 7:3 could bring more remarkable protective effects against focal cerebral ischemia in MCAO rats by alleviating oxidative stress, inflammatory and neuronal apoptosis to protect the blood-brain barrier. Overall, the present study provided benefical evidence for clinical application of CS and CX as a "drug pair".

cGMP signaling pathway in hepatic encephalopathy neuroinflammation and cognition

Hepatic encephalopathy (HE) is a complex neuropsychiatric syndrome that results from liver failure and is characterized by a wide range of symptoms such as alteration in the sleep-waking cycle, neuromuscular coordination, mood, and cognition. The deregulation of nitric oxide (NO)/cyclic guanosine monophosphate (cGMP)/protein kinase G (PKG) signaling pathway is thought to play an important role in the etiology and progression of neurodegenerative diseases, and several studies pointed that the cGMP signaling is impaired in patients with HE and experimental models of chronic hyperammonemia. This review aimed to briefly present the current knowledge of the cGMP signaling pathways in neuroinflammation, neurogenesis, and memory in hepatic encephalopathy and its potential therapeutic role.

Albumin infusion may decrease the incidence and severity of overt hepatic encephalopathy in liver cirrhosis

BACKGROUND

The role of human albumin infusion for the prevention and treatment of overt hepatic encephalopathy (HE) in liver cirrhosis remains unclear.

RESULTS

Among the 708 patients without pre-existing overt HE, albumin infusion significantly decreased the incidence of overt HE (4.20% versus 12.70%, P<0.001) and in-hospital mortality (1.70% versus 5.40%, P=0.008). Among the 182 patients with overt HE at admission or during hospitalization, albumin infusion significantly improved overt HE (84.60% versus 68.10%, P=0.009) and decreased in-hospital mortality (7.70% versus 19.80%, P=0.018). Meta-analysis of 6 studies found that albumin infusion might decrease the risk of overt HE (OR=1.63, P=0.07), but the difference was not statistically significant. Meta-analysis of 3 studies found that albumin infusion significantly improved overt HE (OR=2.40, P=0.04).

CONCLUSIONS

Based on the results of our retrospective study and meta-analysis, albumin infusion might prevent from the occurrence of overt HE and improve the severity of overt HE in cirrhosis. Our retrospective study also suggested that albumin infusion improved the outcomes of cirrhotic patients regardless of overt HE.

METHODS

Cirrhotic patients consecutively admitted between January 2010 and June 2014 were considered in a retrospective study. A 1:1 propensity score matching analysis was performed. Additionally, publications regarding albumin infusion for the management of overt HE were systematically searched. Meta-analyses were performed by random-effect model. Odds ratio (OR) was calculated.

Longitudinal neurometabolic changes in the hippocampus of a rat model of chronic hepatic encephalopathy

BACKGROUND & AIMS

The sequence of events in hepatic encephalopathy (HE) remains unclear. Using the advantages of in vivo 1H-MRS (9.4T) we aimed to analyse the time-course of disease in an established model of type C HE by analysing the longitudinal changes in a large number of brain metabolites together with biochemical, histological and behavioural assessment. We hypothesized that neurometabolic changes are detectable very early, and that these early changes will offer insight into the primary events underpinning HE.

METHODS

Wistar rats underwent bile-duct ligation (BDL) and were studied before BDL and at post-operative weeks 2, 4, 6 and 8 (n = 26). In vivo short echo-time ¹H-MRS (9.4T) of the hippocampus was performed in a longitudinal manner, as were biochemical (plasma), histological and behavioural tests.

RESULTS

Plasma ammonium increased early after BDL and remained high during the study. Brain glutamine increased (+47%) as early as 2-4 weeks post-BDL while creatine (-8%) and ascorbate (-12%) decreased. Brain glutamine and ascorbate correlated closely with rising plasma ammonium, while brain creatine correlated with brain glutamine. The increases in brain glutamine and plasma ammonium were correlated, while plasma ammonium correlated negatively with distance moved. Changes in astrocyte morphology were observed at 4 weeks. These early changes were further accentuated at 6-8 weeks post-BDL, concurrently with the known decreases in brain organic osmolytes.

CONCLUSION

Using a multimodal, in vivo and longitudinal approach we have shown that neurometabolic changes are already noticeable 2 weeks after BDL. These early changes are suggestive of osmotic/oxidative stress and are likely the premise of some later changes. Early decreases in cerebral creatine and ascorbate are novel findings offering new avenues to explore neuroprotective strategies for HE treatment.

LAY SUMMARY

The sequence of events in chronic hepatic encephalopathy (HE) remains unclear, therefore using the advantages of in vivo proton magnetic resonance spectroscopy at 9.4T we aimed to test the hypothesis that neurometabolic changes are detectable very early in an established model of type C HE, offering insight into the primary events underpinning HE, before advanced liver disease confounds the findings. These early, previously unreported neurometabolic changes occurred as early as 2 to 4 weeks after bile-duct ligation, namely an increase in plasma ammonium and brain glutamine, a decrease in brain creatine and ascorbate together with behavioural and astrocyte morphology changes, and continued to progress throughout the 8-week course of the disease.

Brain Edema in Chronic Hepatic Encephalopathy

Brain edema is a common feature associated with hepatic encephalopathy (HE). In patients with acute HE, brain edema has been shown to play a crucial role in the associated neurological deterioration. In chronic HE, advanced magnetic resonance imaging (MRI) techniques have demonstrated that low-grade brain edema appears also to be an important pathological feature. This review explores the different methods used to measure brain edema ex vivo and in vivo in animal models and in humans with chronic HE. In addition, an in-depth description of the main studies performed to date is provided. The role of brain edema in the neurological alterations linked to HE and whether HE and brain edema are the manifestations of the same pathophysiological mechanism or two different cerebral manifestations of brain dysfunction in liver disease are still under debate. In vivo MRI/magnetic resonance spectroscopy studies have allowed insight into the development of brain edema in chronic HE. However, additional in vivo longitudinal and multiparametric/multimodal studies are required (in humans and animal models) to elucidate the relationship between liver function, brain metabolic changes, cellular changes, cell swelling, and neurological manifestations in chronic HE.

Why and when to measure ammonemia in cirrhosis?

Hyperammonemia plays a key role in the pathophysiology of hepatic encephalopathy (HE) and most HE treatments are ammonia-lowering drugs. However, the usefulness of measuring ammonemia in routine practice remains controversial and not recommended systematically even when neurological symptoms are present. First, ammonemia measurement should be carefully performed in order to avoid a falsely elevated result. When performed, a normal ammonemia in a cirrhotic patient with neurological symptoms should lead to reconsider the diagnosis of HE. Indeed, literature data show that most cirrhotic patients with HE have an elevated ammonemia, which is however individually poorly correlated with the severity of symptoms. Nevertheless, elevated ammonemia seems to be a factor of bad prognosis in cirrhosis. A decrease in ammonemia after treatments is well proven but it is not determined whether it is associated with clinical efficacy. Repeated measurements could be useful in this context, especially in non-responders, to help differentiating other causes of encephalopathy, such as drug induced. In acute liver failure, the prognostic value of hyperammonemia is well described and could help an early recognition the most severe forms of this disease. We will also discuss how integrating ammonemia into the diagnostic work-up of liver failure and/or encephalopathy. Ammonemia is also essential to diagnose urea cycle disorders or drug toxicity that both need specific interventions.

Pathogenesis of Hepatic Encephalopathy in Chronic Liver Disease

Hepatic encephalopathy (HE) is a complex neuropsychiatric syndrome that occurs during chronic liver disease (CLD). While ammonia and other precipitating factors in liver disease including inflammation, bile acids, oxidative stress, and lactate play a role in the pathogenesis of HE, the exact mechanism that leads to HE is not fully understood. Notably, accumulating evidence points toward a synergic effect rather than independent actions among precipitating factors that contributes to the development and severity of HE in CLD. Hence, this review is aimed to briefly discuss the single and synergic interplay of pathological factors in the progression and severity of HE.

Targeted upregulation of uncoupling protein 2 within the basal ganglia output structure ameliorates dyskinesia after severe liver failure

Impaired motor function, due to the dysfunction of the basal ganglia, is the most common syndrome of hepatic encephalopathy (HE), and its etiology remains poorly understood. Neural oxidative stress is shown to be the major cellular defects contributing to HE pathogenesis. Mitochondrial uncoupling protein 2 (UCP2) has been implicated in neuroprotection in several neurological disorders. We explored the neuroprotective role of UCP2 within the substantia nigra pars reticulate (SNr), the output structure of the basal ganglia, in HE. The toxin thioacetamide (TAA) induced HE mice showed hypolocomotion, which was associated with decreased ATP levels and loss of antioxidant substances SOD and GSH within the SNr. Stable overexpression of UCP2 via AAV-UCP2 under the control of the UCP2 promoter in bilateral SNr preserved local ATP level, increased antioxidant substances, and ameliorated locomotion defects after severe liver failure. Contrary to UCP2 overexpression, targeted knockdown of UCP2 within bilateral SNr via AAV-UCP2 shRNA exacerbated the impaired mitochondrial dysfunction and hypokinesia in HE mice. The modulatory effects of UCP2 was due to mediation of K⁺-Cl^- cotransporter-2 (KCC2) expression on GABAergic neurons of SNr. Taken together, our results demonstrate that UCP2 exerts a neural protective role at the subcortical level by increasing the resistance of neurons to oxidative stress, which may offer a novel therapeutic target for the treatment of motor dysfunction diseases.

New Insights About Albumin and Liver Disease

Decompensated liver cirrhosis has a dismal prognosis, with an overall survival of 2-4 years, which is worse than for many oncological diseases. Albumin is an important tool in the management of patients with cirrhosis, since it decreases for less than half the risk for post-paracentesis cardiocirculatory dysfunction and mortality associated with spontaneous bacterial infection, as well as, it triplicates the response to terlipressin in patients with hepatorenal syndrome. Recently, research on albumin has been a hot topic, with important new insights such as the characterization of the pleiotropic effects of albumin (which surpass its oncotic properties) and the concept of effective albumin concentration. In fact, patients with liver cirrhosis present posttranslational modifications on albumin that compromises its function. Those modified albumin forms were proved to have prognostic value and its knowledge may change the paradigm of albumin treatment. In this review, we critically summarize the latest evidence on the potential benefits of albumin in patients with end-stage liver disease.

Myosteatosis and sarcopenia are associated with hepatic encephalopathy in patients with cirrhosis

BACKGROUND

Skeletal muscle is known to play a role in hepatic encephalopathy. Fatty infiltration of the muscle (myosteatosis) and muscle mass depletion (sarcopenia) are frequent complications of cirrhosis.

PURPOSE

The purposes of the study were to investigate if myosteatosis and sarcopenia are associated with overt hepatic encephalopathy in patients with cirrhosis and to evaluate their impact on mortality.

METHODS

A total of 675 cirrhotic patients were studied. Computed tomography scans were used to analyze the skeletal muscle. Hepatic encephalopathy was defined by either a hepatic encephalopathy-related hospitalization and/or taking ammonia-lowering treatment (i.e., lactulose, rifaximin).

RESULTS

Myosteatosis was observed in 348 patients (52%), sarcopenia in 242 (36%), and hepatic encephalopathy in 128 (19%) patients. Both myosteatosis (70 vs. 45%, p < 0.001) and sarcopenia (53 vs. 32%, p < 0.001) were more frequent in patients with hepatic encephalopathy. By multivariable regression analysis, both myosteatosis and sarcopenia were associated with a higher risk of hepatic encephalopathy, independent of the MELD score (OR 2.25; 95% CI, 1.32-3.85, p = 0.003 and OR 2.42; 95% CI, 1.43-4.10, p = 0.001, respectively). In univariate Cox proportional hazards analysis, sarcopenia (csHR 2.02; 95% CI, 1.57-2.58, p < 0.001), myosteatosis (csHR 1.45; 95% CI, 1.16-2.91, p = 0.004), and hepatic encephalopathy (csHR 1.61; 95% CI, 1.20-2.18, p = 0.002) were associated with mortality, but only sarcopenia was significant in the multivariable analysis (csHR 2.15; 95% CI, 1.52-3.05, p < 0.001).

CONCLUSIONS

Myosteatosis and sarcopenia are independently associated with overt hepatic encephalopathy in patients with cirrhosis. The association between hepatic encephalopathy and mortality may be explained at least partially by the presence of sarcopenia. These results identify the importance of muscle mass and suggest therapeutic strategies to attenuate muscle mass loss and improve muscle quality.

Taurine supplementation abates cirrhosis-associated locomotor dysfunction

AIM OF THE STUDY

Hepatic encephalopathy and hyperammonemia is a clinical complication associated with liver cirrhosis. The brain is the target organ for ammonia toxicity. Ammonia-induced brain injury is related to oxidative stress, locomotor activity dysfunction, and cognitive deficit, which could lead to permanent brain injury, coma and death if not appropriately managed. There is no promising pharmacological intervention against cirrhosis-associated brain injury. Taurine (TAU) is one of the most abundant amino acids in the human body. Several physiological and pharmacological roles have been attributed to TAU. TAU may act as an antioxidant and is an excellent neuroprotective agent. This study aimed to evaluate the effect of TAU supplementation on cirrhosis-associated locomotor activity disturbances and oxidative stress in the brain.

MATERIAL AND METHODS

Rats underwent bile duct ligation (BDL) surgery, and plasma and brain ammonia level, plasma biochemical parameters, and rats' locomotor function were monitored. Furthermore, brain tissue markers of oxidative stress were assessed.

RESULTS

It was found that plasma and brain ammonia was increased, and markers of liver injury were significantly elevated in the cirrhotic group. Impaired locomotor activity was also evident in BDL rats. Moreover, an increase in brain tissue markers of oxidative stress was detected in the brain of cirrhotic animals. It was found that TAU supplementation (50, 100, and 200 mg/kg, gavage) alleviated brain tissue markers of oxidative stress and improved animals' locomotor activity.

CONCLUSIONS

These data suggest that TAU is a potential protective agent against cirrhosis-associated brain injury.

Resveratrol in Patients with Minimal Hepatic Encephalopathy

BACKGROUND

Minimal Hepatic Encephalopathy (MHE) is characterized by an impairment of social interaction, emotional behavior, sleep disorders, physical and mental symptoms, and diminished Quality of Life (QoL). The aim of our study is evaluating the potential liver health promoting a perspective of Resveratrol (RV) activities and evaluate whether RV treatment may improve health related quality of life (HRQL) and reduce depression and anxiety in patients with MHE.

METHODS

We evaluated depression using the Beck Depression Inventory test, anxiety with State-trait anxiety inventory test, quality of life through SF-36 test, and ammonia serum levels in 70 MHE patients that were randomized into two groups.

RESULTS

In the comparison between RV group and placebo group we observed a decrease in Back Depression Inventory (BDI) (p < 0.001), in State-trait anxiety inventory (STAI) (p < 0.001), and improve in physical function (p < 0.001), in role physical (p < 0.05), in body pain (p < 0.05), in general health (p < 0.001), in vitality (p < 0.05), and in social function (p < 0.001).

CONCLUSIONS

Resveratrol showed efficacy in the treatment of depression, anxiety, and ammonia serum levels, and improved the quality of life Of MHE patients.

Altered Function and Expression of ABC Transporters at the Blood-Brain Barrier and Increased Brain Distribution of Phenobarbital in Acute Liver Failure Mice

This study investigated alterations in the function and expression of P-glycoprotein (P-GP), breast cancer resistance protein (BCRP), and multidrug resistance-associated protein 2 (MRP2) at the blood–brain barrier (BBB) of acute liver failure (ALF) mice and its clinical significance. ALF mice were developed using intraperitoneal injection of thioacetamide. P-GP, BCRP, and MRP2 functions were determined by measuring the ratios of brain-to-plasma concentration of rhodamine 123, prazosin, and dinitrophenyl-S-glutathione, respectively. The mRNA and proteins expression levels of P-GP, BCRP, and MRP2 were evaluated with quantitative real-time PCR and western blot, respectively. MDCK-MDR1 and HCMEC/D3 cells were used to document the effects of the abnormally altered components in serum of ALF mice on the function and expression of P-GP. The clinical significance of alteration in P-GP function and expression was investigated by determining the distribution of the P-GP substrate phenobarbital (60 mg/kg, intravenous administration) in the brain and loss of righting reflex (LORR) induced by the drug (100 mg/kg). The results showed that ALF significantly downregulated the function and expression of both P-GP and BCRP, but increased the function and expression of MRP2 in the brain of mice. Cell study showed that increased chenodeoxycholic acid may be a reason behind the downregulated P-GP function and expression. Compared with control mice, ALF mice showed a significantly higher brain concentration of phenobarbital and higher brain-to-plasma concentration ratios. In accordance, ALF mice showed a significantly larger duration of LORR and shorter latency time of LORR by phenobarbital, inferring the enhanced pharmacological effect of phenobarbital on the central nervous system (CNS). In conclusion, the function and expression of P-GP and BCRP decreased, while the function and expression of MRP2 increased in the brain of ALF mice. The attenuated function and expression of P-GP at the BBB might enhance phenobarbital distribution in the brain and increase phenobarbital efficacy on the CNS of ALF mice.

Hepatic encephalopathy: a critical current review

Hepatic encephalopathy (HE) is a serious neuropsychiatric complication of cirrhosis and/or porto-systemic shunting. The clinical symptoms are widely variable, extending from subtle impairment in mental state to coma. The utility of categorizing the severity of HE accurately and efficiently serves not only to provide practical functional information about the current clinical status of the patient but also gives valuable prognostic information. In the past 20–30 years, there has been rapid progress in understanding the pathophysiological basis of HE; however, the lack of direct correlation between pathogenic factors and the severity of HE make it difficult to select appropriate therapy for HE patients. In this review, we will discuss the classification system and its limitations, the neuropsychometric assessments and their challenges, as well as the present knowledge on the pathophysiological mechanisms. Despite the many prevalent hypotheses around the pathogenesis of the disease, most treatments focus on targeting and lowering the accumulation of ammonia as well as inflammation. However, treatment of minimal HE remains a huge unmet need and a big concerted effort is needed to better define this condition to allow the development of new therapies. We review the currently available therapies and future approaches to treat HE as well as the scientific and clinical data that support their effectiveness.

Ammonia mediates cortical hemichannel dysfunction in rodent models of chronic liver disease

The pathogenesis of hepatic encephalopathy (HE) in cirrhosis is multifactorial and ammonia is thought to play a key role. Astroglial dysfunction is known to be present in HE. Astrocytes are extensively connected by gap junctions formed of connexins, which also exist as functional hemichannels allowing exchange of molecules between the cytoplasm and the extracellular milieu. The astrocyte-neuron lactate shuttle hypothesis suggests that neuronal activity is fueled (at least in part) by lactate provided by neighboring astrocytes. We hypothesized that in HE, astroglial dysfunction could impair metabolic communication between astrocytes and neurons. In this study, we determined whether hyperammonemia leads to hemichannel dysfunction and impairs lactate transport in the cerebral cortex using rat models of HE (bile duct ligation [BDL] and induced hyperammonemia) and also evaluated the effect of ammonia-lowering treatment (ornithine phenylacetate [OP]). Plasma ammonia concentration in BDL rats was significantly reduced by OP treatment. Biosensor recordings demonstrated that HE is associated with a significant reduction in both tonic and hypoxia-induced lactate release in the cerebral cortex, which was normalized by OP treatment. Cortical dye loading experiments revealed hemichannel dysfunction in HE with improvement following OP treatment, while the expression of key connexins was unaffected.

CONCLUSION

The results of the present study demonstrate that HE is associated with central nervous system hemichannel dysfunction, with ammonia playing a key role. The data provide evidence of a potential neuronal energy deficit due to impaired hemichannel-mediated lactate transport between astrocytes and neurons as a possible mechanism underlying pathogenesis of HE. (Hepatology 2017;65:1306-1318).