Updates on the pathophysiology and therapeutic targets for hepatic encephalopathy

Gut microbiota in alcohol-related liver disease: pathophysiology and gut-brain cross talk

Alcohol-related liver disease (ALD) from excessive alcohol intake has a unique gut microbiota profile. The disease progression-free survival in ALD patients has been associated with the degree of gut dysbiosis. The vicious cycles between gut dysbiosis and the disease progression in ALD including: an increase of acetaldehyde production and bile acid secretion, impaired gut barrier, enrichment of circulating microbiota, toxicities of microbiota metabolites, a cascade of pro-inflammatory chemokines or cytokines, and augmentation in the generation of reactive oxygen species. The aforementioned pathophysiology process plays an important role in different disease stages with a spectrum of alcohol hepatitis, ALD cirrhosis, neurological dysfunction, and hepatocellular carcinoma. This review aims to illustrate the pathophysiology of gut microbiota and clarify the gut-brain crosstalk in ALD, which may provide the opportunity of identifying target points for future therapeutic intervention in ALD.

Management of minimal and overt hepatic encephalopathy with branched-chain amino acids: a review of the evidence

Hepatic encephalopathy (HE) is a challenging complication of liver disease that is associated with substantial morbidity and mortality. Branched-chain amino acid (BCAA) supplementation in the management of HE is a debated topic. This narrative review aims to provide an up-to-date review of the topic and includes studies featuring patients with hepatocellular carcinoma. A review of the literature was performed using the online databases MEDLINE and EMBASE for studies between 2002 and December 2022. Keywords 'branched-chain amino acids', 'liver cirrhosis' and 'hepatic encephalopathy' were used. Studies were assessed for inclusion and exclusion criteria. Of 1045 citations, 8 studies met the inclusion criteria. The main outcomes reported for HE was changed in minimal HE (MHE) (n = 4) and/or incidence of overt HE (OHE) (n = 7). Two of the 4 studies reporting on MHE had improvement in psychometric testing in the BCAA group, but there was no change in the incidence of OHE in any of the 7 papers in the BCAA group. There were few adverse effects of BCAA supplementation. This review found weak evidence for BCAA supplementation for MHE, and no evidence for BCAAs for OHE. However, given the relative paucity and methodological heterogeneity of the current research, there is scope for future studies to examine the effects of varying timing, dosage, and frequency of BCAAs on outcomes such as HE. Importantly, research is also needed to examine BCAAs in conjunction with standard therapies for HE such as rifaximin and/or lactulose.

Modern tactics for acute variceal bleeding in liver cirrhosis (Baveno VII guidelines)

Modern tactics for acute variceal bleeding in liver cirrhosis (Baveno VII guidelines)

Nonselective beta-blocker use is associated with increased hepatic encephalopathy-related readmissions in cirrhosis

BACKGROUND

Hepatic encephalopathy (HE) is a neurocognitive condition in cirrhosis leading to frequent hospitalizations. Nonselective beta-blockers (NSBBs) are the mainstay of pharmacologic treatment in cirrhotic patients. We hypothesized that since NSBBs decrease cardiac output and portal flow, the decreased metabolic filtering process of liver parenchyma may lead to increased HE-related hospitalizations.

AIM

To evaluate the impact of NSBB administration on HE-related readmissions in cirrhotic patients.

METHODS

In this retrospective cohort study, we included 393 patients admitted to Baylor University Medical Center for liver-related portal hypertension indications between January 2013 and July 2018. Independent predictors of the first HE-related readmissions were identified using Cox proportional hazards analysis. The cumulative incidence of the first HE-related readmissions between patients receiving NSBBs and not receiving NSBBs was examined using Fine-Gray modeling to account for the competing risk of death or liver transplantation.

RESULTS

The mean age was 58.1 ± 10.2 years and most patients fell into Child class C (49.1%) or B (43.8%). The median Model for End-Stage Liver Disease-Sodium score was 22 (IQR: 11). The cumulative incidence of the first HE-related readmissions was significantly higher in patients taking NSBBs compared to patients not receiving NSBBs (71.8% vs 41.8%, P < 0.0001). In multivariate analysis, after adjusting for demographics, markers of liver disease severity, selective beta-blocker, lactulose and rifaximin use, NSBB use [Hazard ratio: 1.74 (95%CI: 1.29-2.34)] was independently associated with the first HE-related readmissions over a median follow-up of 3.8 years.

CONCLUSION

NSBB use is independently associated with increased HE-related readmissions in patients with cirrhosis, regardless of liver disease severity.

Hepatic Encephalopathy: Current and Emerging Treatment Modalities

Hepatic encephalopathy (HE) is a potentially reversible neurocognitive complication of cirrhosis. It has been reported in at least 30% of patients with cirrhosis and imposes a significant economic burden on caregivers and the healthcare system. Ammonia has been recognized as the culprit in HE development, and all the currently approved treatments mostly act on this toxin to help with HE resolution. After a brief overview of HE characteristics and pathophysiology, this review explores the current accepted treatments for this debilitating complication of cirrhosis. This is followed by an overview of the novel available therapies and a brief focus on future treatment modalities for HE.

Evaluation and management of emergencies in the patient with cirrhosis

The approach to and management of critically ill patients is one of the most versatile themes in emergency medicine. Patients with cirrhosis of the liver have characteristics that are inherent to their disease that can condition modification in acute emergency treatment. Pathophysiologic changes that occur in cirrhosis merit the implementation of an analysis as to whether the overall management of a critically ill patient can generally be applied to patients with cirrhosis of the liver or if they should be treated in a special manner. Through a review of the medical literature, the available information was examined, and the evidence found on the special management required by those patients was narratively synthesized, selecting the most representative decompensations within chronic disease that require emergency treatment.

Evaluation and management of emergencies in the patient with cirrhosis

The approach to and management of critically ill patients is one of the most versatile themes in emergency medicine. Patients with cirrhosis of the liver have characteristics that are inherent to their disease that can condition modification in acute emergency treatment. Pathophysiologic changes that occur in cirrhosis merit the implementation of an analysis as to whether the overall management of a critically ill patient can generally be applied to patients with cirrhosis of the liver or if they should be treated in a special manner. Through a review of the medical literature, the available information was examined, and the evidence found on the special management required by those patients was narratively synthesized, selecting the most representative decompensations within chronic disease that require emergency treatment.

Evaluation of micronutrients among pediatric liver cirrhosis in Shiraz, Iran

Background

Cirrhosis is the final result of most types of liver disease. Zinc, magnesium, and vitamin D have a significantly vital role in the immunologic and physiologic mechanisms in the body. The current study aimed to measure magnesium, zinc, and vitamin D level among children with liver cirrhosis.

Results

One hundred cases were included in the current study. Vitamin D deficiency was found in 53% of the cases. Zinc deficiency was present in 23% of the cases. The magnesium level was more than the normal level among 99% of the cases. There is a significant inverse correlation between zinc level and PELD score (Pearson correlation = − 0.314, P = 0.007).

Conclusion

Zinc deficiency and vitamin D deficiency were seen in children with liver cirrhosis. Serum magnesium level in children with liver cirrhosis was higher than standard. A significant correlation was seen between zinc level and PELD score.

Saul Brusilow: Understanding and treating diseases of ammonia toxicity

This article reviews the scientific career and accomplishments of the late Dr. Saul Brusilow, Professor of Pediatrics at Johns Hopkins. Dr. Brusilow's career was focused on diseases involving hyperammonemia. He and his colleagues developed a set of drugs that could lower ammonia levels in patients with genetic disorders of the urea cycle by providing alternative pathways for the synthesis of excretable nitrogenous molecules. Those drugs and their derivatives represent one of the earliest and most successful drug therapies for genetic diseases. Turning their attention to brain swelling caused by liver disease, Dr. Brusilow and colleagues developed the Osmotic Gliopathy Hypothesis to help explain the mechanism of ammonia toxicity, postulating that high ammonia drives glutamine synthetase in astrocytes to produce elevated levels of glutamine that act as a potent osmolyte, drawing water into the cell and causing cerebral edema. This hypothesis suggests that inhibiting glutamine synthetase with its well-characterized inhibitor, methionine sulfoximine, might prove therapeutic in cases of hepatic encephalopathy, a conclusion supported by their subsequent studies in animals. But although the drugs developed to treat hyperammonemia resulting from urea cycle disorders were successfully developed and approved by the FDA, the compound suggested as a treatment for hepatic encephalopathy was unable to attract sufficient interest and investment to be tested for use in humans.

Cyclic GMP in Liver Cirrhosis-Role in Pathophysiology of Portal Hypertension and Therapeutic Implications

The NO-cGMP signal transduction pathway plays a crucial role in tone regulation in hepatic sinusoids and peripheral blood vessels. In a cirrhotic liver, the key enzymes endothelial NO synthase (eNOS), soluble guanylate cyclase (sGC), and phosphodiesterase-5 (PDE-5) are overexpressed, leading to decreased cyclic guanosine-monophosphate (cGMP). This results in constriction of hepatic sinusoids, contributing about 30% of portal pressure. In contrast, in peripheral arteries, dilation prevails with excess cGMP due to low PDE-5. Both effects eventually lead to circulatory dysfunction in progressed liver cirrhosis. The conventional view of portal hypertension (PH) pathophysiology has been described using the "NO-paradox", referring to reduced NO availability inside the liver and elevated NO production in the peripheral systemic circulation. However, recent data suggest that an altered availability of cGMP could better elucidate the contrasting findings of intrahepatic vasoconstriction and peripheral systemic vasodilation than mere focus on NO availability. Preclinical and clinical data have demonstrated that targeting the NO-cGMP pathway in liver cirrhosis using PDE-5 inhibitors or sGC stimulators/activators decreases intrahepatic resistance through dilation of sinusoids, lowering portal pressure, and increasing portal venous blood flow. These results suggest further clinical applications in liver cirrhosis. Targeting the NO-cGMP system plays a role in possible reversal of liver fibrosis or cirrhosis. PDE-5 inhibitors may have therapeutic potential for hepatic encephalopathy. Serum/plasma levels of cGMP can be used as a non-invasive marker of clinically significant portal hypertension. This manuscript reviews new data about the role of the NO-cGMP signal transduction system in pathophysiology of cirrhotic portal hypertension and provides perspective for further studies.

Novel Insights Into Pathogenesis and Therapeutic Strategies of Hepatic Encephalopathy, From the Gut Microbiota Perspective

Since the 1950s, gradual changes in the gut microbiota of patients with hepatic encephalopathy have been observed. Previous research has indicated potential associations between the gut and brain, and the gut microbiota is becoming a hot topic in research on diseases of the nervous system. However, for the past few decades, studies of hepatic encephalopathy have been restricted to controlling the gut microbiota during macroscopic manipulation, such as probiotic intervention, while its clinical use remains controversial, and the cellular mechanisms underlying this condition are still poorly understood. This thesis seeks to comprehensively understand and explain the role of gut microbiota in hepatic encephalopathy as well as analyze the effects of intervention by regulating the gut microbiota. Evidence is presented that shows that dysbiosis of the gut microbiota is the primary pathological driver of hepatic encephalopathy and impacts pathologic progression via complex regulatory networks. As a result, suggestions were identified for future mechanistic research and improvements in therapeutic strategies for hepatic encephalopathy.

Update on pharmacotherapy of hepatic encephalopathy

Hepatic encephalopathy (HE) is a central nervous system disease caused by serious liver diseases or various portal vein systemic circulation abnormalities. The pathogenesis and pathophysiology of HE have not been fully elucidated yet, and among others, the most important is still the theory of ammonia intoxication proposed in the 1930s. Therefore, reducing blood ammonia is currently the main therapeutic strategy for HE, along with improving nervous system function. Thanks to the clarification of the mechanism underlying ammonia-induced brain cell injury in recent years, researchers have proposed some novel therapeutic targets and related drugs. This work will make a brief summary regarding the update of HE drugs with regard to ammonia reduction, nervous system improvement, and intervention of ammonia toxicity targets.

Fecal microbiota transplantation in hepatic encephalopathy : a review of the current evidence and future perspectives

Hepatic encephalopathy (HE) is a leading cause of hospitalization and morbimortality in advanced cirrhosis with limited therapeutic options available. Given the paramount role of gut microbiota in HE, and the efficacy of fecal microbiota transplantation (FMT) in other diseases, this review intends to summarize the evidence supporting the safety, efficacy and future perspectives of FMT in HE. Current evidence, despite being scarce, points towards FMT being a safe, effective and tolerable procedure in HE. Some unanswered questions remain about the optimal dose, the administration route, the long term effects and the selection of the optimal donor. Future trials, some of which are already underway, will provide us additional evidence and hopefully the necessary answers.

The Current Hepatic Encephalopathy Pipeline

Hepatic encephalopathy (HE) is a complication of acute or chronic liver failure; its mechanism is complex, involving multiple organ systems, and is still being elucidated. The standard of care, lactulose, has remained generally unchanged for decades. However, in recent years, better understanding of the pathophysiology has yielded new therapeutic targets for this reversible condition. These novel treatments act both on traditional pathways established in the ammonia hypothesis and through more recently discovered mechanisms. Here, we review contemporary investigational therapies for HE. We used narrative reviews and searched ClinicalTrials.gov database for the condition "hepatic encephalopathy" through August 29, 2019. Our review yielded six key areas of therapeutic focus: (1) antibiotics against urease-producing gut bacteria, (2) intravenous ammonia scavengers, (3) modified synthetic probiotics, (4) fecal microbiota transplant, (5) brain steroid-modulating agents, and 6) nonlactulose laxatives. Active trials are ongoing in each of these therapeutic areas.

Hepatic Encephalopathy and Nutrition Influences: A Narrative Review

Hepatic encephalopathy (HE) is a potentially reversible neurocognitive condition seen in patients with advanced liver disease. The overt form of HE has been reported in up to 45% of patients with cirrhosis. This debilitating condition is associated with increased morbidity and mortality and imposes a significant burden on the caregivers and healthcare system. After providing an overview of HE epidemiology and pathophysiology, this review focuses on the interaction of HE and frailty, nutrition requirements and recommendations in cirrhotic patients with HE, and current dietary and pharmacologic options for HE treatment.