Serum levels of tumor necrosis factor-alpha correlate with severity of hepatic encephalopathy due to chronic liver failure

[Liver cirrhosis as a multisystem disease]

In recent years, the pathophysiological concept of decompensated liver cirrhosis has undergone significant changes. Until a few years ago, the focus of pathophysiological considerations was on the hyperdynamic circulation resulting from portal hypertension. In recent years, emerging data suggests that increased bacterial translocation leading to systemic inflammation plays an important role in patients with decompensated liver cirrhosis. This inflammation affects a variety of extrahepatic organs. Nowadays, liver cirrhosis is considered not only a condition confined to the liver but rather an inflammatory-triggered multisystem disease. The existing inflammation serves as the common pathophysiological explanation for the diverse impact of liver cirrhosis on several extrahepatic organs. It plays a significant role in the development of conditions such as hepatorenal syndrome, cirrhotic cardiomyopathy, hepatopulmonary syndrome, hepatic encephalopathy, and even in the emergence of cirrhosis-associated relative adrenal insufficiency. These new pathophysiological insights hold clinical significance as they influence the prophylaxis and treatment of patients with decompensated liver cirrhosis.

Pathophysiology of Hepatic Encephalopathy: A Framework for Clinicians

Hepatic encephalopathy (HE) is a neuropsychiatric syndrome that is observed primarily in patients with liver disease. The pathophysiology is complex and involves many factors including ammonia toxicity, dysregulation of central nervous system activity, and excess inflammatory cytokines. Symptoms of HE range from subclinical to debilitating. HE can be difficult to treat and represents a large burden to patients, their caregivers, and the health-care system because of associated resource utilization. This review article provides an overview of the current understanding of the pathophysiology behind HE and where the current research and treatments are pointing toward.

Biomolecular Actions by Intestinal Endotoxemia in Metabolic Syndrome

Metabolic syndrome (MetS) is a combination of metabolic disorders that concurrently act as factors promoting systemic pathologies such as atherosclerosis or diabetes mellitus. It is now believed to encompass six main interacting conditions: visceral fat, imbalance of lipids (dyslipidemia), hypertension, insulin resistance (with or without impairing both glucose tolerance and fasting blood sugar), and inflammation. In the last 10 years, there has been a progressive interest through scientific research investigations conducted in the field of metabolomics, confirming a trend to evaluate the role of the metabolome, particularly the intestinal one. The intestinal microbiota (IM) is crucial due to the diversity of microorganisms and their abundance. Consequently, IM dysbiosis and its derivate toxic metabolites have been correlated with MetS. By intervening in these two factors (dysbiosis and consequently the metabolome), we can potentially prevent or slow down the clinical effects of the MetS process. This, in turn, may mitigate dysregulations of intestinal microbiota axes, such as the lung axis, thereby potentially alleviating the negative impact on respiratory pathology, such as the chronic obstructive pulmonary disease. However, the biomolecular mechanisms through which the IM influences the host's metabolism via a dysbiosis metabolome in both normal and pathological conditions are still unclear. In this study, we seek to provide a description of the knowledge to date of the IM and its metabolome and the factors that influence it. Furthermore, we analyze the interactions between the functions of the IM and the pathophysiology of major metabolic diseases via local and systemic metabolome's relate endotoxemia.

Therapeutic potential of infliximab for pruritus in mice model of cholestasis induced by bile duct ligation: Possible involvement of IL-31

BACKGROUND

Cholestatic pruritus is a distressful sensation that can cause a massive desire of scratching skin. Despite maximum medication therapy, some patients still experience pruritus. In this study, we evaluated the effect of infliximab on cholestatic pruritus induced in mice by bile duct ligation.

METHODS

Twenty-four balb/c mice were randomly assigned to three groups; sham, control, and treatment. The bile duct ligation procedure was performed on mice in the control and treatment groups. After six days, mice in the treatment group received subcutaneous administration of infliximab, and the next day all mice were subjected to the scratching behavior test. Skin, dorsal root ganglia (DRG), and blood samples of mice were collected and evaluated by histopathological, molecular, and biochemical tests.

RESULTS

The scratching behavior has significantly decreased in mice with cholestasis after the administration of infliximab. The levels of TNFα, TNFR1, TNFR2, NF-κB, and IL-31were higher in control mice compared to sham. In addition, expression levels of TNFR1, NF-κB, and IL-31 were decreased in the treatment group compared to the controls in skin and DRG, while TNFR2 levels were decreased only in DRG.

CONCLUSION

Infliximab can block TNFα interaction with receptors and inhibit further inflammatory response. Also, our results suggested that infliximab can suppress IL-31 expression indirectly, which is a well-known cytokine in pruritus pathophysiology Infliximab can be a potential therapeutic approach in resistant pruritus in cholestatic disorders.

Serum and plasma protein biomarkers associated with frailty in patients with cirrhosis

Frailty, a clinical phenotype of decreased physiological reserve, is a strong determinant of adverse health outcomes in patients with cirrhosis. The only cirrhosis-specific frailty metric is the Liver Frailty Index (LFI), which must be administered in person and may not be feasible for every clinical scenario. We sought to discover candidate serum/plasma protein biomarkers that could differentiate frail from robust patients with cirrhosis. A total of 140 adults with cirrhosis awaiting liver transplantation in the ambulatory setting with LFI assessments and available serum/plasma samples were included. We selected 70 pairs of patients on opposite ends of the frailty spectrum (LFI>4.4 for frail and LFI<3.2 for robust) who were matched by age, sex, etiology, HCC, and Model for End-Stage Liver Disease-Sodium. Twenty-five biomarkers with biologically plausible associations with frailty were analyzed using ELISA by a single laboratory. Conditional logistic regression was used to examine their association with frailty. Of the 25 biomarkers analyzed, we identified 7 proteins that were differentially expressed between frail and robust patients. We observed differences in 6 of the 7 proteins in the expected direction: (a) higher median values in frail versus robust with growth differentiation factor-15 (3682 vs. 2249 pg/mL), IL-6 (17.4 vs. 6.4 pg/mL), TNF-alpha receptor 1 (2062 vs. 1627 pg/mL), leucine-rich alpha-2 glycoprotein (44.0 vs. 38.6 μg/mL), and myostatin (4066 vs. 6006 ng/mL) and (b) lower median values in frail versus robust with alpha-2-Heremans-Schmid glycoprotein (0.11 vs. 0.13 mg/mL) and free total testosterone (1.2 vs. 2.4 ng/mL). These biomarkers represent inflammatory, musculoskeletal, and endocrine/metabolic systems, reflecting the multiple physiological derangements observed in frailty. These data lay the foundation for confirmatory work and development of a laboratory frailty index for patients with cirrhosis to improve diagnosis and prognostication.

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

BACKGROUND

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

AIM

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

PATIENTS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Dysregulation of Astrocytic Glutamine Transport in Acute Hyperammonemic Brain Edema

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

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

BACKGROUND AND AIMS

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

APPROACH AND RESULTS

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

CONCLUSIONS

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

The mechanistic and prognostic implications of heart rate variability analysis in patients with cirrhosis

Chronic liver damage leads to scarring of the liver tissue and ultimately a systemic illness known as cirrhosis. Patients with cirrhosis exhibit multi-organ dysfunction and high mortality. Reduced heart rate variability (HRV) is a hallmark of cirrhosis, reflecting a state of defective cardiovascular control and physiological network disruption. Several lines of evidence have revealed that decreased HRV holds prognostic information and can predict survival of patients independent of the severity of liver disease. Thus, the aim of this review is to shed light on the mechanistic and prognostic implications of HRV analysis in patients with cirrhosis. Notably, several studies have extensively highlighted the critical role systemic inflammation elicits in conferring the reduction in patients' HRV. It appears that IL-6 is likely to play a central mechanistic role, whereby its levels also correlate with manifestations, such as autonomic neuropathy and hence the partial uncoupling of the cardiac pacemaker from autonomic control. Reduced HRV has also been reported to be highly correlated with the severity of hepatic encephalopathy, potentially through systemic inflammation affecting specific brain regions, involved in both cognitive function and autonomic regulation. In general, the prognostic ability of HRV analysis holds immense potential in improving survival rates for patients with cirrhosis, as it may indeed be added to current prognostic indicators, to ultimately increase the accuracy of selecting the recipient most in need of liver transplantation. However, a network physiology approach in the future is critical to delineate the exact mechanistic basis by which decreased HRV confers poor prognosis.

Clinical and biomarker assessment of frailty in liver transplantation

PURPOSE OF REVIEW

Liver cirrhosis results in progressive decline, or frailty, which leads to poor outcomes and decreased survival. Multiple biomarkers and clinical assessment tools for quantifying frailty in liver transplant candidates exist, but a universal scoring protocol is lacking. Criteria vary between studies and correlation with patient outcome is not always clear. This review aims to summarize the pertinent biomarkers and assessment tools of frailty in cirrhosis.

RECENT FINDINGS

As cirrhosis progresses, the resultant 'frailty' is an inseparable independent predictor of pre and posttransplant mortality. Pro-inflammatory, neuroendocrine, and adipokine factors are dysregulated - leading to paradoxical anorexia and downregulation of orexigenic signals. The resulting catabolic utilization of amino and fatty acids leads to progressive malnutrition and sarcopenia. Both functional and imaging criteria define sarcopenia in cirrhotic patients, and degree of debilitation correlates with mortality. Liver-disease-specific frailty biomarkers and scoring tools are optimal to assess physical dysfunction in cirrhotics to promote early diagnosis and intervention.

SUMMARY

Liver cirrhosis and resulting frailty are progressive and portend a poor patient prognosis. A comprehensive, validated algorithm for detecting and quantifying frailty specific to liver disease would allow for standardization and facile application in the clinical setting. Early diagnosis is key for timely intervention and improved patient outcomes.

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

Background

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

Methods

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

Results

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

Conclusions

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

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

Liver disease is a growing public health concern. Hepatic encephalopathy, the syndrome of brain dysfunction secondary to liver disease, is a frequent complication of both acute and chronic liver disease and cerebral edema (CE) is a key feature. While altered ammonia metabolism is a key contributor to hepatic encephalopathy and CE in liver disease, there is a growing appreciation that additional mechanisms contribute to CE. In this review we will begin by presenting three classic perspectives that form a foundation for a discussion of CE in liver disease: 1) CE is unique to acute liver failure, 2) CE in liver disease is only cytotoxic, and 3) CE in liver disease is primarily an osmotically mediated consequence of ammonia and glutamine metabolism. We will present each classic perspective along with more recent observations that call in to question that classic perspective. After highlighting these areas of debate, we will explore the leading contemporary mechanisms hypothesized to contribute to CE during liver disease.

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

BACKGROUND

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

AIM

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

METHODS

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

RESULTS

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

CONCLUSION

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

Dietary approach and gut microbiota modulation for chronic hepatic encephalopathy in cirrhosis

Hepatic encephalopathy (HE) is a common and serious neuropsychiatric complication of cirrhosis, acute liver failure, and porto-systemic shunting. HE largely contributes to the morbidity of patients with liver disease, severely affecting the quality of life of both patients and their relatives and being associated with poor prognosis. Its presentation is largely variable, manifesting with a broad spectrum of cognitive abnormalities ranging from subtle cognitive impairment to coma. The pathogenesis of HE is complex and has historically been linked with hyperammonemia. However, in the last years, it has become evident that the interplay of multiple actors, such as intestinal dysbiosis, gut hyperpermeability, and neuroinflammation, is of crucial importance in its genesis. Therefore, HE can be considered a result of a dysregulated gut-liver-brain axis function, where cognitive impairment can be reversed or prevented by the beneficial effects induced by “gut-centric” therapies, such as non-absorbable disaccharides, non-absorbable antibiotics, probiotics, prebiotics, and fecal microbiota transplantation. In this context dietary modifications, by modulating the intestinal milieu, can also provide significant benefit to cirrhotic patients with HE. This review will provide a comprehensive insight into the mechanisms responsible for gut-liver-brain axis dysregulation leading to HE in cirrhosis. Furthermore, it will explore the currently available therapies and the most promising future treatments for the management of patients with HE, with a special focus on the dietary approach.

Metformin modifies glutamine metabolism in an in vitro and in vivo model of hepatic encephalopathy

AIM

to analyze the effect of metformin on ammonia production derived from glutamine metabolism in vitro and in vivo.

METHODS

twenty male Wistar rats were studied for 28 days after a porto-caval anastomosis (n = 16) or a sham operation (n = 4). Porto-caval shunted animals were randomized into two groups (n = 8) and either received 30 mg/kg/day of metformin for two weeks or were control animals. Plasma ammonia concentration, Gls gene expression and K-type glutaminase activity were measured in the small intestine, muscle and kidney. Furthermore, Caco2 were grown in different culture media containing glucose/glutamine as the main carbon source and exposed to different concentrations of the drug. The expression of genes implicated in glutamine metabolism were analyzed.

RESULTS

metformin was associated with a significant inhibition of glutaminase activity levels in the small intestine of porto-caval shunted rats (0.277 ± 0.07 IU/mg vs 0.142 ± 0.04 IU/mg) and a significant decrease in plasma ammonia (204.3 ± 24.4 µg/dl vs 129.6 ± 16.1 µg/dl). Glucose withdrawal induced the expression of the glutamine transporter SLC1A5 (2.54 ± 0.33 fold change; p < 0.05). Metformin use reduced MYC levels in Caco2 and consequently, SLC1A5 and GLS expression, with a greater effect in cells dependent on glutaminolytic metabolism.

CONCLUSION

metformin regulates ammonia homeostasis by modulating glutamine metabolism in the enterocyte, exerting an indirect control of both the uptake and degradation of glutamine. This entails a reduction in the production of metabolites and energy through this pathway and indirectly causes a decrease in ammonia production that could be related to a decreased risk of HE development.

Umbelliferone prevents oxidative stress, inflammation and hematological alterations, and modulates glutamate-nitric oxide-cGMP signaling in hyperammonemic rats

Hepatic encephalopathy (HE) is a serious neuropsychiatric complication that occurs as a result of liver failure. Umbelliferone (UMB; 7-hydroxycoumarin) is a natural product with proven hepatoprotective activity; however, nothing has yet been reported on its protective effect against hyperammonemia, the main culprit behind the symptoms of HE. Here, we evaluated the effect of UMB against ammonium chloride (NH₄Cl)-induced hyperammonemia, oxidative stress, inflammation and hematological alterations in rats. We demonstrated the modulatory role of UMB on the glutamate-nitric oxide (NO)-cGMP pathways in the cerebrum of rats. Rats received intraperitoneal injections of NH₄Cl (3 times/week) for 8 weeks and concomitantly received 50 mg/kg UMB. NH₄Cl-induced rats showed significantly elevated blood ammonia and liver function markers. Lipid peroxidation and NO were increased in the liver and cerebrum of rats while the antioxidant defenses were declined. UMB significantly reduced blood ammonia, liver function markers, lipid peroxidation and NO, and enhanced the antioxidant defenses in NH₄Cl-induced rats. UMB significantly prevented anemia, leukocytosis, thrombocytopenia and prolongation of PT and aPTT. Hyperammonemic rats showed elevated levels of cerebral TNF-α, IL-1β and glutamine as well as increased activity and expression of Na⁺/K⁺-ATPase, effects that were significantly reversed by UMB. In addition, UMB down-regulated nitric oxide synthase and soluble guanylate cyclase in the cerebrum of hyperammonemic rats. In conclusion, this study provides evidence that UMB protects against hyperammonemia via attenuation of oxidative stress and inflammation. UMB prevents hyperammonemia associated hematological alterations and therefore represents a promising protective agent against the deleterious effects of excess ammonia.

TNFα induced up-regulation of Na+,K+,2Cl- cotransporter NKCC1 in hepatic ammonia clearance and cerebral ammonia toxicity

The devastating consequences of hepatic failure include hepatic encephalopathy, a severe, life threatening impairment of neuronal function. Hepatic encephalopathy is caused by impaired hepatic clearance of NH₄⁺. Cellular NH₄⁺ uptake is accomplished mainly by the Na⁺,K⁺,2Cl⁻ cotransporter. Here we show that hepatic clearance of NH₄⁺ is impaired in TNFα deficient as well as TNFR1&TNFR2 double knockout mice, which both develop hyperammonemia. Despite impaired hepatic clearance of NH₄⁺, TNFα deficient mice and TNFR1 deficient mice were protected against acute ammonia intoxication. While 54% of the wild-type mice and 60% of TNFR2 deficient mice survived an NH₄⁺ load, virtually all TNFα deficient mice and TNFR1 deficient mice survived the treatment. Conversely, TNFα treatment of wild type mice sensitized the animals to the toxic effects of an NH₄⁺ load. The protection of TNFα-deficient mice against an NH₄⁺ load was paralleled by decreased cerebral expression of NKCC1. According to the present observations, inhibition of TNFα formation and/or NKCC1 may be strategies to favorably influence the clinical course of hepatic encephalopathy.

Ascitic Fluid Calprotectin and Serum Procalcitonin as Accurate Diagnostic Markers for Spontaneous Bacterial Peritonitis

Background/Aims

The diagnosis of spontaneous bacterial peritonitis (SBP) is based on a polymorphonuclear leukocytes (PMNs) exceeding 250/μL in ascitic fluid. The aim of the study was to evaluate serum procalcitonin and ascitic fluid calprotectin as accurate diagnostic markers for detecting SBP.

Methods

Seventy-nine patients with cirrhotic ascites were included. They were divided into a SBP group, including 52 patients, and a non-SBP group of 27 patients. Serum procalcitonin, ascitic calprotectin, and serum and ascitic levels of tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) were measured using an enzyme-linked immunosorbent assay.

Results

Serum procalcitonin and ascitic calprotectin were significantly higher in SBP patients than in non-SBP patients. Significant increases in both serum and ascitic levels of TNF-α and IL-6 were observed in SBP patients versus non-SBP patients. At a cutoff value of 0.94 ng/mL, serum procalcitonin had 94.3% sensitivity and 91.8% specificity for detecting SBP. In addition, at a cutoff value of 445 ng/mL, ascitic calprotectin had 95.4% sensitivity and 85.2% specificity for detecting SBP. Both were positively correlated with ascitic fluid proteins, PMN count, TNF-α, and IL-6.

Conclusions

According to our findings, determination of serum procalcitonin levels and ascitic calprotectin appears to provide satisfactory diagnostic markers for the diagnosis of SBP.

Plasma Glucose Level Is Predictive of Serum Ammonia Level After Retrograde Occlusion of Portosystemic Shunts

OBJECTIVE

The purpose of this study was to evaluate predictors of reduction in ammonia levels by occlusion of portosystemic shunts (PSS) in patients with cirrhosis.

MATERIALS AND METHODS

Forty-eight patients with cirrhosis (21 women, 27 men; mean age, 67.8 years) with PSS underwent balloon-occluded retrograde transvenous obliteration (BRTO) at one institution between February 2008 and June 2014. The causes of cirrhosis were hepatitis B in one case, hepatitis C in 20 cases, alcohol in 15 cases, nonalcoholic steatohepatitis in eight cases, and other conditions in four cases. The Child-Pugh classes were A in 24 cases, B in 23 cases, and C in one case. The indication for BRTO was gastric varices in 40 cases and hepatic encephalopathy in eight cases. Testing was conducted before and 1 month after the procedure. Statistical analyses were performed to identify predictors of a clinically significant decline in ammonia levels after BRTO.

RESULTS

Occlusion of PSS resulted in a clinically significant decrease in ammonia levels accompanied by increased portal venous flow and improved Child-Pugh score. Univariate analyses showed that a reduction in ammonia levels due to BRTO was significantly related to lower plasma glucose levels, higher RBC counts, and higher hemoglobin concentration before the treatment. Furthermore, multivariate logistic regression identified preoperative plasma glucose level as the strongest independent predictor of a significant ammonia reduction in response to BRTO. In addition, although BRTO resulted in significantly declined ammonia levels in patients with normal glucose tolerance before the procedure, ammonia levels were not significantly decreased after shunt occlusion in patients with diabetes mellitus or impaired glucose tolerance before BRTO, according to 75-g oral glucose tolerance test results.

CONCLUSION

Preoperative plasma glucose level is a useful predictor of clinically significant ammonia reduction resulting from occlusion of PSS in patients with cirrhosis. Even if PSS are present, control of blood ammonia levels by BRTO alone may be difficult in patients with glucose intolerance.

Commiphora molmol Modulates Glutamate-Nitric Oxide-cGMP and Nrf2/ARE/HO-1 Pathways and Attenuates Oxidative Stress and Hematological Alterations in Hyperammonemic Rats

Hyperammonemia is a serious complication of liver disease and may lead to encephalopathy and death. This study investigated the effects of Commiphora molmol resin on oxidative stress, inflammation, and hematological alterations in ammonium chloride- (NH₄Cl-) induced hyperammonemic rats, with an emphasis on the glutamate-NO-cGMP and Nrf2/ARE/HO-1 signaling pathways. Rats received NH₄Cl and C. molmol for 8 weeks. NH₄Cl-induced rats showed significant increase in blood ammonia, liver function markers, and tumor necrosis factor-alpha (TNF-α). Concurrent supplementation of C. molmol significantly decreased circulating ammonia, liver function markers, and TNF-α in hyperammonemic rats. C. molmol suppressed lipid peroxidation and nitric oxide and enhanced the antioxidant defenses in the liver, kidney, and cerebrum of hyperammonemic rats. C. molmol significantly upregulated Nrf2 and HO-1 and decreased glutamine and nitric oxide synthase, soluble guanylate cyclase, and Na⁺/K⁺-ATPase expression in the cerebrum of NH₄Cl-induced hyperammonemic rats. Hyperammonemia was also associated with hematological and coagulation system alterations. These alterations were reversed by C. molmol. Our findings demonstrated that C. molmol attenuates ammonia-induced liver injury, oxidative stress, inflammation, and hematological alterations. This study points to the modulatory effect of C. molmol on glutamate-NO-cGMP and Nrf2/ARE/HO-1 pathways in hyperammonemia. Therefore, C. molmol might be a promising protective agent against hyperammonemia.

Cytokine-Mediated Immunopathogenesis of Hepatitis B Virus Infections

Hepatitis B virus (HBV) infection is a worldwide health problem, with approximately one third of populations have been infected, among which 3-5% of adults and more than 90% of children developed to chronic HBV infection. Host immune factors play essential roles in the outcome of HBV infection. Thus, ineffective immune response against HBV may result in persistent virus replications and liver necroinflammations, then lead to chronic HBV infection, liver cirrhosis, and even hepatocellular carcinoma. Cytokine balance was shown to be an important immune characteristic in the development and progression of hepatitis B, as well as in an effective antiviral immunity. Large numbers of cytokines are not only involved in the initiation and regulation of immune responses but also contributing directly or indirectly to the inhibition of virus replication. Besides, cytokines initiate downstream signaling pathway activities by binding to specific receptors expressed on the target cells and play important roles in the responses against viral infections and, therefore, might affect susceptibility to HBV and/or the natural course of the infection. Since cytokines are the primary causes of inflammation and mediates liver injury after HBV infection, we have discussed recent advances on the roles of various cytokines [including T helper type 1 cells (Th1), Th2, Th17, regulatory T cells (Treg)-related cytokines] in different phases of HBV infection and cytokine-related mechanisms for impaired viral control and liver damage during HBV infection. We then focus on experimental therapeutic applications of cytokines to gain a better understanding of this newly emerging aspect of disease pathogenesis.

Combined Intraperitoneal and Intrathecal Etanercept Reduce Increased Brain Tumor Necrosis Factor-Alpha and Asymmetric Dimethylarginine Levels and Rescues Spatial Deficits in Young Rats after Bile Duct Ligation

BACKGROUND

Rats subjected to bile duct ligation (BDL) exhibit increased systemic oxidative stress and brain dysfunction characteristic of hepatic encephalopathy (HE), including fatigue, neurotransmitter alterations, cognitive and motor impairment, and brain inflammation. The levels of tumor necrosis factor-alpha (TNF-α) and asymmetric dimethylarginine (ADMA) are both increased in plasma and brain in encephalopathy induced by chronic liver failure. This study first determined the temporal profiles of TNF-α and ADMA in the plasma, brain cortex, and hippocampus in young BDL rats. Next, we examined whether etanercept was beneficial in preventing brain damage.

METHODS

Young rats underwent sham ligation or BDL at day 17 ± 1 for 4 weeks. Treatment group rats were administered etanercept (10 mg/kg) intraperitoneally (IP) three times per week with or without etanercept (100 μg) intrathecally (IT) three times in total.

RESULTS

We found increased plasma TNF-α, soluble tumor necrosis factor receptor 1 (sTNFR1), soluble tumor necrosis factor receptor 2 (sTNFR2), and ADMA levels, increased cortical TNF-α mRNA and protein and ADMA, and hippocampal TNF-α mRNA and protein, and spatial defects in young BDL rats. The increase in cortex TNF-α mRNA and ADMA were reduced by IP etanercept or combined IP and IT etanercept. Dually IP/IT etanercept administration reduced the increased cortical and hippocampal TNF-α mRNA and protein level as well as spatial deficits.

CONCLUSIONS

We conclude that combined intraperitoneal and intrathecal etanercept reduce increased brain TNF-α and ADMA levels and rescues spatial deficits in young rats after BDL.

Potential targeted therapies for the inflammatory pathogenesis of hepatic encephalopathy

Hepatic encephalopathy (HE) is a severe neuropsychiatric complication of acute and chronic liver dysfunction, and is characterized by a spectrum that ranges from mild neuropsychological disturbances to coma. Although ammonia plays a critical role in the pathogenesis of HE, the plasma concentrations of ammonia and manifest symptoms of HE are not always consistent in patients with HE. Recently, a substantial body of evidence has indicated that inflammation acts in concert with ammonia in the pathogenesis of HE. Meanwhile, emerging novel and potential therapeutic strategies, including N-acetylcysteine, hypothermia, minocycline, non-steroidal anti-inflammatory drugs, tumour necrosis factor-alpha antagonists and p38 inhibitors, have been reported to ameliorate systemic inflammation and neuroinflammation, improve or reverse neuropsychiatric manifestations, and prevent the onset and progression of HE in patients and/or animal models of acute or chronic liver failure. These results point to the possible therapeutic utility of decreasing inflammation in the treatment of HE, and translation of these experimental results to the clinic may provide novel and promising therapeutic approaches for patients with HE secondary to acute or chronic liver failure. This review will provide an overview of these potential targeted therapies in the prophylaxis and treatment of HE.

Inflammation: A novel target of current therapies for hepatic encephalopathy in liver cirrhosis

Hepatic encephalopathy (HE) is a severe neuropsychiatric syndrome that most commonly occurs in decompensated liver cirrhosis and incorporates a spectrum of manifestations that ranges from mild cognitive impairment to coma. Although the etiology of HE is not completely understood, it is believed that multiple underlying mechanisms are involved in the pathogenesis of HE, and one of the main factors is thought to be ammonia; however, the ammonia hypothesis in the pathogenesis of HE is incomplete. Recently, it has been increasingly demonstrated that inflammation, including systemic inflammation, neuroinflammation and endotoxemia, acts in concert with ammonia in the pathogenesis of HE in cirrhotic patients. Meanwhile, a good number of studies have found that current therapies for HE, such as lactulose, rifaximin, probiotics and the molecular adsorbent recirculating system, could inhibit different types of inflammation, thereby improving the neuropsychiatric manifestations and preventing the progression of HE in cirrhotic patients. The anti-inflammatory effects of these current therapies provide a novel therapeutic approach for cirrhotic patients with HE. The purpose of this review is to describe the inflammatory mechanisms behind the etiology of HE in cirrhosis and discuss the current therapies that target the inflammatory pathogenesis of HE.

The expression levels of prolyl oligopeptidase responds not only to neuroinflammation but also to systemic inflammation upon liver failure in rat models and cirrhotic patients

Background

Liver failure in experimental animals or in human cirrhosis elicits neuroinflammation. Prolyl oligopeptidase (PREP) has been implicated in neuroinflammatory events in neurodegenerative diseases: PREP protein levels are increased in brain glial cells upon neuroinflammatory insults, but the circulating PREP activity levels are decreased in multiple sclerosis patients in a process probably mediated by bioactive peptides. In this work, we studied the variation of PREP levels upon liver failure and correlated it with several inflammatory markers to conclude on the relation of PREP with systemic and/or neuroinflammation.

Methods

PREP enzymatic activity and protein levels measured with immunological techniques were determined in the brain and plasma of rats with portacaval shunt (PCS) and after treatment with ibuprofen. Those results were compared with the levels of PREP measured in plasma from cirrhotic patients with or without minimal hepatic encephalopathy (MHE). Levels of several pro-inflammatory cytokines and those of NO/cGMP homeostasis metabolites were measured in PCS rats and cirrhotic patients to conclude on the role of PREP in inflammation.

Results

In PCA rats, we found that PREP levels are significantly increased in the hippocampus, striatum and cerebellum, that in the cerebellum the PREP increase was significantly found in the extracellular space and that the levels were restored to those measured in control rats after administration of an anti-inflammatory agent, ibuprofen. In cirrhotic patients, circulatory PREP activity was found to correlate to systemic and neuroinflammatory markers and had a negative correlation with the severity of the disease, although no clear relation to MHE.

Conclusions

These results support the idea that PREP levels could be used as indicators of cirrhosis severity in humans, and using other markers, it might contribute to assessing the level of neuroinflammation in those patients. This work reports, for the first time, that PREP is secreted to the extracellular space in the cerebellum most probably due to glial activation and supports the role of the peptidase in the inflammatory response.

Diagnostic utility of interferon gamma-induced protein 10 kDa in spontaneous bacterial peritonitis: single-center study

BACKGROUND AND AIMS

Spontaneous bacterial peritonitis (SBP) is an important cause of mortality and morbidity in cirrhotic patients with ascites. The diagnosis of SBP is mainly made on the basis of a polymorphonuclear leukocyte cell count exceeding 250/μl in ascitic fluid. However, this procedure is subjective. We aimed to evaluate serum and ascitic fluid interferon-γ-induced protein (IP-10) as accurate diagnostic markers for detecting SBP.

METHODS

A total of 425 consecutive patients with ascites were included. Serum and ascitic fluid of IP-10, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) were measured using an enzyme-linked immunosorbent assay.

RESULTS

Patients were divided into an SBP group, including 61 patients, and a non-SBP group, including 364 patients. Serum and ascitic IP-10 were significantly higher in SBP patients than in patients without SBP (1855±825 vs. 955±510 pg/ml; P<0.001 and 2160±994 vs. 1110±623 pg/ml; P<0.001), respectively. There was a significant increase in both serum and ascitic levels of TNF-α and IL-6 in SBP patients than in patients without SBP. At a cut-off value of 1915 pg/ml, serum IP-10 had 91% sensitivity and 89% specificity for detecting SBP (area under the curve: 0.912). Also, at a cut-off value of 2355 pg/ml, ascitic IP-10 had 92.5% sensitivity and 87% specificity for detecting SBP (area under the curve: 0.943). Both were correlated with ascitic fluid proteins, polymorphonuclear count, TNF-α, and IL-6.

CONCLUSION

Serum and ascitic IP-10, TNF-α, and IL-6 are significantly increased in SBP patients versus patients without SBP. Serum level of IP-10 is more specific and sensitive, such as ascites. Thus, it seems to represent a satisfactory diagnostic marker for the diagnosis of SBP.

Detecting minimal hepatic encephalopathy in an endemic country for hepatitis B: the role of psychometrics and serum IL-6

BACKGROUND & AIMS

It remains unknown what the prevalence of minimal hepatic encephalopathy is in Taiwan, a highly endemic country for chronic viral hepatitis infection. It is also unclear whether abnormal serum cytokine levels can be indicative of the presence of minimal hepatic encephalopathy. We aimed to standardize the tests of psychometric hepatic encephalopathy score and predictive value of proinflammatory cytokines in minimal hepatic encephalopathy in Taiwan.

METHODS

180 healthy subjects and 94 cirrhotic patients without a history of overt hepatic encephalopathy from a tertiary center were invited to participate in this cross-sectional study. Blood sampling for determination of serum levels of interleukin 6 and 18 and tumor necrosis factor-α was performed. Based on the normogram of psychometric hepatic encephalopathy score from healthy volunteers, patients with minimal hepatic encephalopathy were identified from the cirrhotic patients using the criterion of a psychometric hepatic encephalopathy score less than -4.

RESULTS

In the healthy subjects, age and education were predictors of subtests of psychometric hepatic encephalopathy score. Minimal hepatic encephalopathy was identified in 27 (29%) cirrhotic patients. Serum interleukin 6 level (OR = 6.50, 95% CI = 1.64-25.76, P = 0.008) was predictive of the presence of minimal hepatic encephalopathy after multivariate analysis.

CONCLUSIONS

The psychometric hepatic encephalopathy score can be a useful tool for detecting patients with minimal hepatic encephalopathy in Taiwan and around one third of cirrhotic outpatients fulfill this diagnosis. A high serum interleukin 6 level is predictive of the presence of minimal hepatic encephalopathy.

Liver Failure Impairs the Intrahepatic Elimination of Interleukin-6, Tumor Necrosis Factor-Alpha, Hepatocyte Growth Factor, and Transforming Growth Factor-Beta

The strategic location of the liver and its metabolic activity make it a key organ regulating homeostasis. Our purpose was to examine its participation in removal of cytokines: interleukin-6 (Il-6), tumor necrosis factor-alpha (TNF-α), hepatocyte growth factor (HGF), and transforming growth factor-beta (TGF-β) from the portal circulation in human. 20 liver donors and 20 patients with end-stage liver failure were included in the study. Their blood was collected during liver transplantation from the portal, hepatic, and peripheral vein, and the hepatic artery and cytokines' concentrations were determined. Using the results the mathematical model of cytokine elimination by the liver was developed. In donors significantly lower levels of IL-6, TNF-α, HGF, and TGF-β were detected in portal blood compared to hepatic vein. In patients with cirrhosis there were no significant differences of IL-6, TNF-α, and TGF-β levels between portal and hepatic veins. Significantly higher level of HGF in hepatic compared to portal vein was observed. In healthy liver elimination of the cytokines prevailed over their synthesis, as reflected by the positive values of the elimination ratios. In the cirrhotic liver elimination ratios of Il-6, HGF, and TGF-β were negative indicating the prevalence of intrahepatic synthesis of cytokines over their removal.

Hepatic encephalopathy in patients with acute decompensation of cirrhosis and acute-on-chronic liver failure

Hepatic encephalopathy in a hospitalized cirrhotic patient is associated with a high mortality rate and its presence adds further to the mortality of patients with acute-on-chronic liver failure (ACLF). The exact pathophysiological mechanisms of HE in this group of patients are unclear but hyperammonemia, systemic inflammation (including sepsis, bacterial translocation, and insulin resistance) and oxidative stress, modulated by glutaminase gene alteration, remain as key factors. Moreover, alcohol misuse, hyponatremia, renal insufficiency, and microbiota are actively explored. HE diagnosis requires exclusion of other causes of neurological, metabolic and psychiatric dysfunction. Hospitalization in the ICU should be considered in every patient with overt HE, but particularly if this is associated with ACLF. Precipitating factors should be identified and treated as required. Evidence-based specific management options are limited to bowel cleansing and non-absorbable antibiotics. Ammonia lowering drugs, such as glycerol phenylbutyrate and ornithine phenylacetate show promise but are still in clinical trials. Albumin dialysis may be useful in refractory cases. Antibiotics, prebiotics, and treatment of diabetes reduce systemic inflammation. Where possible and not contraindicated, large portal-systemic shunts may be embolized but liver transplantation is the most definitive step in the management of HE in this setting. HE in patients with ACLF appears to be clinically and pathophysiologically distinct from that of acute decompensation and requires further studies and characterization.

Rats with minimal hepatic encephalopathy due to portacaval shunt show differential increase of translocator protein (18 kDa) binding in different brain areas, which is not affected by chronic MAP-kinase p38 inhibition

Neuroinflammation plays a main role in neurological deficits in rats with minimal hepatic encephalopathy (MHE) due to portacaval shunt (PCS). Treating PCS rats with SB239063, an inhibitor of MAP-kinase-p38, reduces microglial activation and brain inflammatory markers and restores cognitive and motor function. The translocator protein-(18-kDa) (TSPO) is considered a biomarker of neuroinflammation. TSPO is increased in brain of PCS rats and of cirrhotic patients that died in hepatic coma. Rats with MHE show strong microglial activation in cerebellum and milder in other areas when assessed by MHC-II immunohistochemistry. This work aims were assessing: 1) whether binding of TSPO ligands is selectively increased in cerebellum in PCS rats; 2) whether treatment with SB239063 reduces binding of TSPO ligands in PCS rats; 3) which cell type (microglia, astrocytes) increases TSPO expression. Quantitative autoradiography was used to assess TSPO-selective (3)H-(R)-PK11195 binding to different brain areas. TSPO expression increased differentially in PCS rats, reaching mild expression in striatum or thalamus and very high levels in cerebellum. TSPO was expressed in astrocytes and microglia. Treatment with SB239063 did not reduces (3)[H]-PK11195 binding in PCS rats. SB239063 reduces microglial activation and levels of inflammatory markers, but not binding of TSPO ligands. This indicates that SB239063-induced neuroinflammation reduction in PCS rats is not mediated by effects on TSPO. Also, enhanced TSPO expression is not always associated with cognitive or motor deficits. If enhanced TSPO expression plays a role in mechanisms leading to neurological alterations in MHE, SB239063 would interfere these mechanisms at a later step.

Brain edema in acute liver failure: mechanisms and concepts

Brain edema and associated increase in intracranial pressure continue to be lethal complications of acute liver failure (ALF). Abundant evidence suggests that the edema in ALF is largely cytotoxic brought about by swelling of astrocytes. Elevated blood and brain ammonia levels have been strongly implicated in the development of the brain edema. Additionally, inflammation and sepsis have been shown to contribute to the astrocyte swelling/brain edema in the setting of ALF. We posit that ammonia initiates a number of signaling events, including oxidative/nitrative stress (ONS), the mitochondrial permeability transition (mPT), activation of the transcription factor (NF-κB) and signaling kinases, all of which have been shown to contribute to the mechanism of astrocyte swelling. All of these factors also impact ion-transporters, including Na(+), K(+), Cl(-) cotransporter and the sulfonylurea receptor 1, as well as the water channel protein aquaporin-4 resulting in a perturbation of cellular ion and water homeostasis, ultimately resulting in astrocyte swelling/brain edema. All of these events are also potentiated by inflammation. This article reviews contemporary knowledge regarding mechanisms of astrocyte swelling/brain edema formation which hopefully will facilitate the identification of therapeutic targets capable of mitigating the brain edema associated with ALF.

Human serum albumin, systemic inflammation, and cirrhosis

Human serum albumin (HSA) is one of the most frequent treatments in patients with decompensated cirrhosis. Prevention of paracentesis-induced circulatory dysfunction, prevention of type-1 HRS associated with bacterial infections, and treatment of type-1 hepatorenal syndrome are the main indications. In these indications treatment with HSA is associated with improvement in survival. Albumin is a stable and very flexible molecule with a heart shape, 585 residues, and three domains of similar size, each one containing two sub-domains. Many of the physiological functions of HSA rely on its ability to bind an extremely wide range of endogenous and exogenous ligands, to increase their solubility in plasma, to transport them to specific tissues and organs, or to dispose of them when they are toxic. The chemical structure of albumin can be altered by some specific processes (oxidation, glycation) leading to rapid clearance and catabolism. An outstanding feature of HSA is its capacity to bind lipopolysaccharide and other bacterial products (lipoteichoic acid and peptidoglycan), reactive oxygen species, nitric oxide and other nitrogen reactive species, and prostaglandins. Binding to NO and prostaglandins are reversible, so they can be transferred to other molecules at different sites from their synthesis. Through these functions, HSA modulates the inflammatory reaction. Decompensated cirrhosis is a disease associated systemic inflammation, which plays an important role in the pathogenesis of organ or system dysfunction/failure. Although, the beneficial effects of HAS have been traditionally attributed to plasma volume expansion, they could also relate to its effects modulating systemic and organ inflammation.

Hyperammonemia and systemic inflammatory response syndrome predicts presence of hepatic encephalopathy in dogs with congenital portosystemic shunts

Hepatic encephalopathy (HE) is an important cause of morbidity and mortality in patients with liver disease. The pathogenesis of he is incompletely understood although ammonia and inflammatory cytokines have been implicated as key mediators. To facilitate further mechanistic understanding of the pathogenesis of HE, a large number of animal models have been developed which often involve the surgical creation of an anastomosis between the hepatic portal vein and the caudal vena cava. One of the most common congenital abnormalities in dogs is a congenital portosystemic shunt (cpss), which closely mimics these surgical experimental models of HE. Dogs with a cPSS often have clinical signs which mimic clinical signs observed in humans with HE. Our hypothesis is that the pathogenesis of HE in dogs with a cPSS is similar to humans with HE. The aim of the study was to measure a range of clinical, haematological and biochemical parameters, which have been linked to the development of HE in humans, in dogs with a cPSS and a known HE grade. One hundred and twenty dogs with a cPSS were included in the study and multiple regression analysis of clinical, haematological and biochemical variables revealed that plasma ammonia concentrations and systemic inflammatory response syndrome scores predicted the presence of HE. Our findings further support the notion that the pathogenesis of canine and human HE share many similarities and indicate that dogs with cPSS may be an informative spontaneous model of human HE. Further investigations on dogs with cPSS may allow studies on HE to be undertaken without creating surgical models of HE thereby allowing the number of large animals used in animal experimentation to be reduced.

The liver-brain axis in liver failure: neuroinflammation and encephalopathy

Systemic inflammation is common in liver failure and its acquisition is a predictor of hepatic encephalopathy severity. New studies provide convincing evidence for a role of neuroinflammation (inflammation of the brain per se) in liver failure; this evidence includes activation of microglia, together with increased synthesis in situ of the proinflammatory cytokines TNF, IL-1β and IL-6. Liver-brain signalling mechanisms in liver failure include: direct effects of systemic proinflammatory molecules, recruitment of monocytes after microglial activation, brain accumulation of ammonia, lactate and manganese, and altered permeability of the blood-brain barrier. Ammonia and cytokines might act synergistically. Existing strategies to reduce ammonia levels (including lactulose, rifaximin and probiotics) have the potential to dampen systemic inflammation, as does albumin dialysis, mild hypothermia and N-acetylcysteine, the latter two agents acting at both peripheral and central sites. Minocycline, an agent with potent central anti-inflammatory properties, reduces neuroinflammation, brain oedema and encephalopathy in liver failure, as does the anti-TNF agent etanercept.

Correlation between interleukin-6 and ammonia in patients with overt hepatic encephalopathy due to cirrhosis

OBJECTIVE

Previous studies have shown that elevated serum levels of interleukin-6 (IL-6) correlate with the severity of overt hepatic encephalopathy (OHE) in cirrhotic patients. However, the correlation between serum IL-6 levels and plasma ammonia levels in these patients remains unclear. Therefore, the present study investigated this correlation between both variables in cirrhotic patients with OHE.

METHODS

Fifty-five cirrhotic patients with various grades of OHE, 29 cirrhotic patients without OHE, and 30 healthy controls were recruited. Concentrations of plasma ammonia and serum IL-6 were simultaneously measured.

RESULTS

In cirrhotic patients with OHE, the severity of OHE, represented by the West Haven criteria, correlated with serum IL-6 levels (r=0.43, P<0.05) and plasma ammonia levels (r=0.59, P<0.05). IL-6 and ammonia were found to be significant independent predictors of OHE severity (P<0.05 for both variables). Furthermore, the severity of liver cirrhosis, determined by Child-Pugh scores, correlated with serum IL-6 levels (r=0.45, P<0.05) and plasma ammonia levels (r=0.68, P<0.05) in these patients. Moreover, there was a significant positive correlation between serum IL-6 levels and plasma ammonia levels (r=0.58, P<0.05) in cirrhotic patients with OHE, but not in patients without OHE (r=0.42, P>0.05) or healthy controls (r=0.27, P>0.05). The correlation between IL-6 and ammonia was independent of infectious precipitating factors.

CONCLUSIONS

The results of the present study suggest that IL-6 might be involved in the mechanism by which ammonia contributes to the pathogenesis of OHE. There is also evidence of a potential synergistic interaction between proinflammatory cytokines and ammonia in the pathogenesis of OHE.

Increased risk of cognitive impairment in cirrhotic patients with bacterial infections

BACKGROUND & AIMS

A causal relationship between infection, systemic inflammation, and hepatic encephalopathy (HE) has been suggested in cirrhosis. No study, however, has specifically examined, in cirrhotic patients with infection, the complete pattern of clinical and subclinical cognitive alterations and its reversibility after resolution. Our investigation was aimed at describing the characteristics of cognitive impairment in hospitalized cirrhotic patients, in comparison with patients without liver disease, with and without infection.

METHODS

One hundred and fifty cirrhotic patients were prospectively enrolled. Eighty-one patients without liver disease constituted the control group. Bacterial infections and sepsis were actively searched in all patients independently of their clinical evidence at entry. Neurological and psychometric assessment was performed at admission and in case of nosocomial infection. The patients were re-evaluated after the resolution of the infection and 3months later.

RESULTS

Cognitive impairment (overt or subclinical) was recorded in 42% of cirrhotics without infection, in 79% with infection without SIRS and in 90% with sepsis. The impairment was only subclinical in controls and occurred only in patients with sepsis (42%). Multivariate analysis selected infection as the only independent predictor of cognitive impairment (OR 9.5; 95% CI 3.5-26.2; p=0.00001) in cirrhosis. The subclinical alterations detected by psychometric tests were also strongly related to the infectious episode and reversible after its resolution.

CONCLUSIONS

Infections are associated with a worse cognitive impairment in cirrhotics compared to patients without liver disease. The search and treatment of infections are crucial to ameliorate both clinical and subclinical cognitive impairment of cirrhotic patients.

Serum endotoxin, inflammatory mediators, and magnetic resonance spectroscopy before and after treatment in patients with minimal hepatic encephalopathy

BACKGROUND

Minimal hepatic encephalopathy (MHE) represents the mildest form of hepatic encephalopathy (HE), with abnormal neuropsychologic findings. Inflammatory response may be important in the pathogenesis of MHE. On magnetic resonance spectroscopy (MRS), improvement of metabolic ratios after liver transplantation suggests an important role of myoinositol (mI) and choline (cho) in the development of MHE.

AIMS

To investigate arterial ammonia, tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, IL-18, serum endotoxin, and MRS before and after treatment in MHE.

PATIENTS AND METHODS

Sixty patients of cirrhosis with MHE were randomized to two groups, Gr. MHE-L (n = 30), treated with lactulose for 3 months, and Gr. MHE-NL (n = 30), who did not received lactulose. Arterial ammonia, TNF-α, IL-6, IL-18, serum endotoxin, and MRS were performed in all patients at baseline and at 3 months and 20 patients of cirrhosis without MHE and 20 healthy controls.

RESULTS

After 3 months, median arterial ammonia (69.4 vs 52.7 mcg/dL), TNF-α (26.6 vs 22 pg/mL), IL-6 (17.6 vs 12.4 pg/mL), IL-18 (42.5 vs 29 pg/mL), and serum endotoxin (0.68 vs 0.43 EU/mL) significantly decreased in Gr. MHE-L compared with baseline (P < 0.0001), while no change was seen in Gr. MHE-NL patients. On MRS, compared with patients of cirrhosis without MHE, mI and cho were significantly lower (P < 0.001) and glutamine (Glx) was significantly higher in both MHE groups (P < 0.001). After 3 months, mI and cho increased and Glx decreased significantly in Gr. MHE-L (P < 0.001), without changes in Gr. MHE-NL patients. Psychometric hepatic encephalopathic score (PHES) correlated well with arterial ammonia, TNF-α, IL-6, IL-18, serum endotoxin, and metabolic parameters on MRS.

CONCLUSIONS

Arterial ammonia, inflammatory mediators (TNF-α, IL-6, IL-18), and serum endotoxin reduce and MRS abnormalities improve after treatment with lactulose in patients with MHE.

Role of diabetes mellitus on hepatic encephalopathy

Hepatic encephalopathy is the main cognitive dysfunction in cirrhotic patients associated with impaired prognosis. Hyperammonemia plus inflammatory response do play a crucial role on hepatic encephalopathy. However, in some patients HE appeared without hyperammonemia and patients with increased levels of ammonia could not show cognitive dysfunction. This has led to investigate other factors that could act in a synergistic way. Diabetes mellitus and insulin resistance are characterized by releasing and enhancing these pro-inflammatory cytokines and, additionally, has been related to hepatic encephalopathy. Indeed, patients with diabetes showed raised risk of over hepatic encephalopathy in comparison with non-cirrhotics. Type 2 diabetes mellitus could impair hepatic encephalopathy by different mechanisms that include: a) increasing glutaminase activity; b) impairing gut motility and promoting constipation, intestinal bacterial overgrowth and bacterial translocation. Despite of insufficient clarity about the practicability of anti-diabetic therapy and the most efficacious therapy, we would have to pay a special attention to the management of type 2 diabetes mellitus and insulin resistance in cirrhotic patients.

Serum endotoxin and inflammatory mediators in patients with cirrhosis and hepatic encephalopathy

BACKGROUND

Recent observations suggest that inflammatory response may be important in the pathogenesis of hepatic encephalopathy. The aim of the study was to measure arterial ammonia, tumour necrosis factor-alpha, Interleukin-6, Interleukin-18, and serum endotoxin levels and their correlation with different grades of hepatic encephalopathy.

METHODS

120 patients with cirrhosis were enrolled: 20 patients each of cirrhosis with grades I, II, III and IV hepatic encephalopathy, cirrhosis with and without minimal hepatic encephalopathy and healthy controls were tested for arterial ammonia, tumour necrosis factor-alpha, Interleukin-6, Interleukin-18 and serum endotoxin levels.

RESULTS

Median arterial ammonia, tumour necrosis factor-alpha, Interleukin-6, Interleukin-18 and serum endotoxin levels were significantly higher in patient with hepatic encephalopathy and minimal hepatic encephalopathy as compared to patients without minimal hepatic encephalopathy and healthy controls. Arterial ammonia (r = 0.72, p = 0.03), tumour necrosis factor alpha (r = 0.87, p = 0.02), Interleukin-6 (r = 0.50, p = 0.05), Interleukin-18 (r = 0.76, p = 0.02) and serum endotoxin (r = 0.91, p = 0.01) correlated with higher grades of hepatic encephalopathy.

CONCLUSION

In hepatic encephalopathy arterial ammonia, inflammatory mediators, and serum endotoxin are elevated and correlate with encephalopathy grade.

Norcantharidin facilitates LPS-mediated immune responses by up-regulation of AKT/NF-κB signaling in macrophages

Norcantharidin (NCTD), a demethylated analog of cantharidin, is a common used clinical drug to inhibit proliferation and metastasis of cancer cells. But the role of NCTD in modulating immune responses remains unknown. Here, we investigated the function and mechanism of NCTD in regulation of TLR4 associated immune response in macrophages. We evaluated the influence of NCTD on host defense against invaded pathogens by acute peritonitis mouse model, ELISA, Q-PCR, nitrite quantification, phagocytosis assay and gelatin zymography assay. Our data showed that the survival and the serum concentrations of IL-6 and TNF-α were all enhanced by NCTD significantly in peritonitis mouse model. Accordingly, LPS-induced cytokine, nitric oxide and MMP-9 production as well as the phagocytosis of bacteria were all up-regulated by NCTD in a dose dependent manner in both RAW264.7 cells and bone marrow-derived macrophages (BMMs). Then we further analyzed TLR4 associated signaling pathway by Western blot, Immunofluorescence and EMSA in the presence or absence of LPS. The phosphorylation of AKT and p65 at serine 536 but not serine 468 was enhanced obviously by NCTD in a dose dependent manner, whereas the degradation of IκBα was little effected. Consequently, the nuclear translocation and DNA binding ability of NF-κB was also increased by NCTD obviously in RAW264.7 cells. Our results demonstrated that NCTD could facilitate LPS-mediated immune response through promoting the phosphorylation of AKT/p65 and transcriptional activity of NF-κB, thus reprofiling the traditional anti-tumor drug NCTD as a novel immune regulator in promoting host defense against bacterial infection.

Primary cultures of astrocytes: their value in understanding astrocytes in health and disease

During the past few decades of astrocyte research it has become increasingly clear that astrocytes have taken a central position in all central nervous system activities. Much of our new understanding of astrocytes has been derived from studies conducted with primary cultures of astrocytes. Such cultures have been an invaluable tool for studying roles of astrocytes in physiological and pathological states. Many central astrocytic functions in metabolism, amino acid neurotransmission and calcium signaling were discovered using this tissue culture preparation and most of these observations were subsequently found in vivo. Nevertheless, primary cultures of astrocytes are an in vitro model that does not fully mimic the complex events occurring in vivo. Here we present an overview of the numerous contributions generated by the use of primary astrocyte cultures to uncover the diverse functions of astrocytes. Many of these discoveries would not have been possible to achieve without the use of astrocyte cultures. Additionally, we address and discuss the concerns that have been raised regarding the use of primary cultures of astrocytes as an experimental model system.

Dogs with congenital porto-systemic shunting (cPSS) and hepatic encephalopathy have higher serum concentrations of C-reactive protein than asymptomatic dogs with cPSS

Hepatic encephalopathy (HE) is a cause of significant morbidity and mortality in patients with liver disorders and a wide range of rodent models of HE have been described to facilitate studies into the pathogenesis and treatment of HE. However, it is widely acknowledged that no individual model perfectly mimics human HE and there is a particular need for spontaneous, larger animal models. One common congenital abnormality in dogs is the portosystemic shunt (cPSS) which causes clinical signs that are similar to human HE such as ataxia, disorientation, lethargy and occasionally coma. As inflammation has recently been shown to be associated with HE in humans, we hypothesised that inflammation would similarly be associated with HE in dogs with cPSS. To examine this hypothesis we measured C-reactive protein (CRP) in 30 healthy dogs, 19 dogs with a cPSS and no HE and 27 dogs with a cPSS and overt HE. There was a significant difference in CRP concentration between healthy dogs and dogs with HE (p < 0.001) and between dogs with HE and without HE (p < 0.05). The novel finding that there is an association between inflammation and canine HE strengthens the concept that HE in dogs with cPSS shares a similar pathogenesis to humans with HE. Consequently, dogs with a cPSS may be a good spontaneous model of human HE in which to further examine the role of inflammation and development of HE.

Pro-inflammatory cytokines are raised in extrahepatic portal venous obstruction, with minimal hepatic encephalopathy

BACKGROUND AND AIMS

Minimal hepatic encephalopathy (MHE) and hyperammonemia are seen in patients with extrahepatic portal venous obstruction (EHPVO). Inflammation has been shown to play an important role in the pathogenesis of hepatic encephalopathy in cirrhotics. This study assessed serum pro-inflammatory cytokines and their correlation with hyperammonemia, (1)H-magnetic resonance (MR) spectroscopy-derived brain glutamine, and diffusion tensor imaging (DTI)-derived metrics in patients with EPHVO, with and without MHE.

METHODS

Neuropsychological tests, DTI, (1)H-MR spectroscopy, and estimation of blood ammonia and pro-inflammatory cytokines (tumor necrosis factor-α[TNF-α] and interleukin-6 [IL-6]) were done in 20 patients with EHPVO and eight healthy controls.

RESULTS

Pro-inflammatory cytokines (TNF-α and IL-6), blood ammonia, brain glutamine, and mean diffusivity were increased in both patient groups, as compared to controls. Patients with MHE (n-12) had significantly higher TNF-α, IL-6, blood ammonia, brain glutamine, and mean diffusivity, signifying brain edema, than controls. A significant, positive correlation was seen between TNF-α and IL-6 and between blood ammonia and TNF-α, IL-6, and brain glutamine. Significant, positive correlations of TNF-α, IL-6, and blood ammonia with mean diffusivity values were seen in various brain regions, including spectroscopy voxel-derived mean diffusivity.

CONCLUSION

Patients with extrahepatic portal vein obstruction have inflammation and hyperammonemia made evident by higher blood TNF-α, IL-6, ammonia, and brain glutamine levels. A significant correlation between hyperammonemia, pro-inflammatory cytokines, and cerebral edema on DTI in various brain regions suggests that both these factors play a role in the pathogenesis of MHE in these patients.

Marked potentiation of cell swelling by cytokines in ammonia-sensitized cultured astrocytes

Background

Brain edema leading to high intracranial pressure is a lethal complication of acute liver failure (ALF), which is believed to be cytotoxic due to swelling of astrocytes. In addition to the traditional view that elevated levels of blood and brain ammonia are involved in the mechanism of brain edema in ALF, emerging evidence suggests that inflammatory cytokines also contribute to this process. We earlier reported that treatment of astrocyte cultures with a pathophysiological concentration of ammonia (5 mM NH₄Cl) resulted in the activation of nuclear factor-kappaB (NF-κB) and that inhibition of such activation diminished astrocyte swelling, suggesting a key role of NF-κB in the mechanism of ammonia-induced astrocyte swelling. Since cytokines are also well-known to activate NF-κB, this study examined for additive/synergistic effects of ammonia and cytokines in the activation of NF-κB and their role in astrocyte swelling.

Methods

Primary cultures of astrocytes were treated with ammonia and cytokines (TNF-α, IL-1, IL-6, IFN-γ, each at 10 ng/ml), individually or in combination, and cell volume was determined by the [³H]-O-methylglucose equilibration method. The effect of ammonia and cytokines on the activation of NF-κB was determined by immunoblots.

Results

Cell swelling was increased by ammonia (43%) and by cytokines (37%) at 24 h. Simultaneous co-treatment with cytokines and ammonia showed no additional swelling. By contrast, cultures pretreated with ammonia for 24 h and then exposed to cytokines for an additional 24 h, showed a marked increase in astrocyte swelling (129%). Treatment of cultures with ammonia or cytokines alone also activated NF-κB (80-130%), while co-treatment had no additive effect. However, in cultures pre-treated with ammonia for 24 h, cytokines induced a marked activation of NF-κB (428%). BAY 11-7082, an inhibitor of NF-κB, completely blocked the astrocyte swelling in cultures pre-treated with ammonia and followed by the addition of a mixture of cytokines.

Conclusion

Our results indicate that ammonia and a mixture of cytokines each cause astrocyte swelling but when these agents are added simultaneously, no additive effects were found. On the other hand, when cells were initially treated with ammonia and 24 h later given a mixture of cytokines, a marked potentiation in cell swelling and NF-κB activation occurred. These data suggest that the potentiation in cell swelling is a consequence of the initial activation of NF-κB by ammonia. These findings provide a likely mechanism for the exacerbation of brain edema in patients with ALF in the setting of sepsis/inflammation.

Changing face of hepatic encephalopathy: Role of inflammation and oxidative stress

The face of hepatic encephalopathy (HE) is changing. This review explores how this neurocognitive disorder, which is associated with both acute and chronic liver injury, has grown to become a dynamic syndrome that spans a spectrum of neuropsychological impairment, from normal performance to coma. The central role of ammonia in the pathogenesis of HE remains incontrovertible. However, over the past 10 years, the HE community has begun to characterise the key roles of inflammation, infection, and oxidative/nitrosative stress in modulating the pathophysiological effects of ammonia on the astrocyte. This review explores the current thoughts and evidence base in this area and discusses the potential role of existing and novel therapies that might abrogate the oxidative and nitrosative stresses inflicted on the brain in patients with, or at risk of developing, HE.