Orchestration of Tryptophan-Kynurenine Pathway, Acute Decompensation, and Acute-on-Chronic Liver Failure in Cirrhosis

Bupi Yishen formula attenuates kidney injury in 5/6 nephrectomized rats via the tryptophan-kynurenic acid-aryl hydrocarbon receptor pathway

BACKGROUND

Bupi Yishen Formula (BYF), a patent traditional Chinese medicine (TCM) formulation, has been used in the clinical treatment of chronic kidney disease (CKD). However, the mechanism of action of BYF has not been fully elucidated.

METHOD

To investigate the variation in the metabolic profile in response to BYF treatment in a rat model of 5/6 nephrectomy (Nx), rats in the treatment groups received low- or high-dose BYF. At the end of the study, serum and kidney samples were collected for biochemical, pathological, and western blotting analysis. Metabolic changes in serum were analyzed by liquid chromatography-tandem mass spectrometry.

RESULTS

The results showed that BYF treatment could reduce kidney injury, inhibit inflammation and improve renal function in a dose-dependent manner. In total, 405 and 195 metabolites were identified in negative and positive ion modes, respectively. Metabolic pathway enrichment analysis of differential metabolites based on the Kyoto Encyclopedia of Genes and Genomes database identified 35 metabolic pathways, 3 of which were related to tryptophan metabolism. High-dose BYF reduced the level of kynurenic acid (KA) by more than 50%, while increasing melatonin 25-fold and indole-3-acetic acid twofold. Expression levels of aryl hydrocarbon receptor (AhR), Cyp1A1, and CyP1B1 were significantly reduced in the kidney tissue of rats with high-dose BYF, compared to 5/6 Nx rats.

CONCLUSION

BYF has a reno-protective effect against 5/6 Nx-induced CKD, which may be mediated via inhibition of the tryptophan-KA-AhR pathway.

Urine organic acids may be useful biomarkers for metabolic syndrome and its components in Korean adults

OBJECTIVES

Although metabolic syndrome (MetS) and its components are defined clinically, those with MetS may have various derangements in metabolic pathways. Thus, this study aimed to evaluate the traits of urine organic acid metabolites indicating the metabolic intermediates of the pathways in the subjects with MetS.

METHODS

This cross-sectional study included 246 men and 283 women in a hospital health check-up setting. Urine organic acid metabolites were assayed via high-performance liquid chromatography-mass spectrometry analyses. A high level of each metabolite was defined as the fifth quintile of the distribution.

RESULTS

The subjects with MetS had high levels of pyruvate, α-ketoglutarate, α-ketoisovalerate, α-ketoisocaproate, formiminoglutamate, and quinolinate (odds ratios from 1.915 to 2.809 in logistic models adjusted for age and sex). Among the metabolites, pyruvate, formiminoglutamate, and quinolinate were not independent of homeostatic model assessment of insulin resistance (HOMA2-IR). Several metabolites were associated with one or more components of MetS and HOMA2-IR.

CONCLUSIONS

Urine organic acid metabolites in MetS are characterized in altered carbohydrate and amino acid metabolism. MetS shared some traits in insulin resistance. These findings may promote the understanding of the pathophysiology of MetS.

Acute-on-chronic liver failure: A distinct clinical syndrome

There are different operating definitions for acute-on-chronic liver failure (ACLF) in different geographic regions. Consortia in Western countries have developed definitions that apply to patients with cirrhosis, while consortia in Asia have developed definitions that apply to patients with chronic liver diseases with or without cirrhosis. Investigators of the Chinese and Western Consortia believe that ACLF can be precipitated by acute insults that are intrahepatic (e.g. alcoholic hepatitis) or extrahepatic (e.g. bacterial infection, gastrointestinal haemorrhage), and that extrahepatic organ system failures can be used to define ACLF. In contrast, the Asia Pacific consortium believe that ACLF is only defined by an acute onset of liver failure in response to an acute hepatic insult. Of note, although ACLF has received different operating definitions, every definition recognises that ACLF is a distinct clinical entity. This article provides an updated overview of the distinctive features of ACLF according to the definitions used to characterise it. In addition, we discuss future directions for research aimed at identifying the hallmarks of ACLF.

New clinical and pathophysiological perspectives defining the trajectory of cirrhosis

Traditionally, the complications of cirrhosis, namely variceal bleeding, ascites and hepatic encephalopathy, were thought to result predominantly from circulatory dysfunction and altered organ perfusion arising as a result of portal hypertension. Over the past 20 years, large, international prospective studies have indicated the importance of systemic inflammation and organ immunopathology as additional determinants of organ dysfunction in cirrhosis, which not only manifests in the liver, brain, circulation and the kidneys, but also the immune system, gut, muscles, adrenal glands, reproductive organs, heart and lungs. This review provides an overview of the traditional and emerging concepts around the initiation and maintenance of organ dysfunction in cirrhosis and proposes a new paradigm based upon a better understanding of acute decompensation of cirrhosis. The interaction between the traditional concepts and the emerging perspectives remains a matter of great interest and the basis for future research.

Changes in the epidemiology and management of bacterial infections in cirrhosis

Patients with cirrhosis are susceptible to develop infections because of immune dysfunction, changes in microbiome and increase in bacterial translocation from the gut to systemic circulation. Bacterial infections can worse the clinical course of the disease, triggering the development of complications such as acute kidney injury, hepatic encephalopathy, organ failures and acute on chronic liver failure. In recent years, the spread of multi drug resistant bacteria made more challenging the management of infections in patients with cirrhosis. Hence, the mortality rate associated to sepsis is increasing in these patients. Therefore, the optimization of the management of infections has a high priority in cirrhosis. Herein we reviewed the recent changes in the epidemiology and the management of bacterial infections in patients with liver cirrhosis.

Fiber scaffold bioartificial liver therapy relieves acute liver failure and extrahepatic organ injury in pigs

Rationale: Acute liver failure (ALF) causes severe liver injury and a systemic inflammatory response, leading to multiorgan failure with a high short-term mortality. Bioartificial liver (BAL) therapy is a promising approach that is hampered by the lack of appropriate bioreactors and carriers to retain hepatic cell function and poor understanding of BAL treatment mechanisms in ALF and extrahepatic organ injury. Recently, we used a fiber scaffold bioreactor (FSB) for the high-density, three-dimensional (3D) culture of primary porcine hepatocytes (PPHs) combined with an absorption component to construct a BAL and verified its function in a D-galactosamine (D-gal)-induced ALF porcine model to evaluate its protective effects on the liver and extrahepatic organs. Methods: Male pigs were randomized into standard/supportive therapy (ST), ST+no-cell BAL (ST+Sham BAL) and ST+BAL groups and received treatment 48 h after receiving a D-gal injection. Changes in blood chemistry and clinical symptoms were monitored for 120 h. Tissues and plasma were collected for analysis by pathological examination, immunoblotting, quantitative PCR and immunoassays. Results: PPHs cultured in the FSB obtained sufficient aeration and nutrition for high-density, 3D culture and maintained superior viability and functionality (biosynthesis and detoxification) compared with those cultured in flasks. All the animals developed ALF, acute kidney injury (AKI) and hepatic encephalopathy (HE) 48 h after D-gal infusion and received corresponding therapies. Animals in the BAL group showed markedly improved survival (4/5; 80%) compared with those in the ST+Sham BAL (0/5; p < 0.001) and ST (0/5; p < 0.001) groups. The levels of blood ammonia and biochemical and inflammatory indices were alleviated after BAL treatment. Increased liver regeneration and attenuations in the occurrence and severity of ALF, AKI and HE were observed in the ST+BAL group compared with the ST (p = 0.0009; p = 0.038) and ST+Sham BAL (p = 0.011; p = 0.031) groups. Gut leakage, the plasma endotoxin level, bacterial translocation, and peripheral and neuroinflammation were alleviated in the ST+BAL group compared with those in the other groups. Conclusions: BAL treatment enhanced liver regeneration and alleviated the systemic inflammatory response and extrahepatic organ injury to prolong survival in the ALF model and has potential as a therapeutic approach for ALF patients.

Oral Microbiome Characteristics in Patients With Autoimmune Hepatitis

Autoimmune hepatitis (AIH) is a common cause of liver cirrhosis. To identify the characteristics of the oral microbiome in patients with AIH, we collected 204 saliva samples including 68 AIH patients and 136 healthy controls and performed microbial MiSeq sequencing after screening. All samples were randomly divided into discovery cohorts (46 AIH and 92 HCs) and validation cohorts (22 AIH and 44 HCs). Moreover, we collected samples of 12 AIH patients from Hangzhou for cross-regional validation. We described the oral microbiome characteristics of AIH patients and established a diagnostic model. In the AIH group, the oral microbiome diversity was significantly increased. The microbial communities remarkably differed between the two groups. Seven genera, mainly Fusobacterium, Actinomyces and Capnocytophaga, were dominant in the HC group, while 51 genera, Streptococcus, Veillonella and Leptotrichia, were enriched in the AIH group. Notably, we found 23 gene functions, including Membrane Transport, Carbohydrate Metabolism, and Glycerolipid metabolism that were dominant in AIH and 31 gene functions that prevailed in HCs. We further investigated the correlation between the oral microbiome and clinical parameters. The optimal 5 microbial markers were figured out through a random forest model, and the distinguishing potential achieved 99.88% between 46 AIH and 92 HCs in the discovery cohort and 100% in the validation cohort. Importantly, the distinguishing potential reached 95.55% in the cross-regional validation cohort. In conclusion, this study is the first to characterize the oral microbiome in AIH patients and to report the successful establishment of a diagnostic model and the cross-regional validation of microbial markers for AIH. Importantly, oral microbiota-targeted biomarkers may be able to serve as powerful and noninvasive diagnostic tools for AIH.

The Microbiome Meets Nanotechnology: Opportunities and Challenges in Developing New Diagnostic Devices

Monitoring of the human microbiome is an emerging area of diagnostics for personalized medicine. Here, the potential of different nanomaterials and nanobiosensing technologies is reviewed for the development of novel diagnostic devices for the detection and measurement of microbiome-related biomarkers. Moreover, the current and future landscape of microbiome-based diagnostics is defined by exploring the advantages and disadvantages of current nanotechnology-based approaches, especially in the context of developing point-of-care (PoC) devices that would meet the international guidelines known as REASSURED (Real-time connectivity; Ease of specimen collection; Affordability; Sensitivity; Specificity; User-friendliness; Rapid & robust operation; Equipment-free; and Deliverability). Finally, the strategies of the latest international scientific consortia working in this field are analyzed, the current microbiome diagnostics market are reported and the principal ethical, legal, and societal issues related to microbiome R&D and innovation are discussed.

Assessing the role of amino acids in systemic inflammation and organ failure in patients with ACLF

BACKGROUND & AIMS

Systemic inflammation and organ failure(s) are the hallmarks of acute-on-chronic liver failure (ACLF), yet their pathogenesis remains uncertain. Herein, we aimed to assess the role of amino acids in these processes in patients with ACLF.

METHODS

The blood metabolomic database of the CANONIC study (comprising 137 metabolites, with 43% related to amino acids) - obtained in 181 patients with ACLF and 650 with acute decompensation without ACLF (AD) - was reanalyzed with a focus on amino acids, in particular 9 modules of co-regulated metabolites. We also compared blood metabolite levels between ACLF and AD.

RESULTS

The main findings in ACLF were: i) Metabolite modules were increased in parallel with increased levels of markers of systemic inflammation and oxidative stress. ii) Seventy percent of proteinogenic amino acids were present and most were increased. iii) A metabolic network, comprising the amino acids aspartate, glutamate, the serine-glycine one-carbon metabolism (folate cycle), and methionine cycle, was activated, suggesting increased purine and pyrimidine nucleotide synthesis. iv) Cystathionine, L-cystine, glutamate and pyroglutamate, which are involved in the transsulfuration pathway (a methionine cycle branch) were increased, consistent with increased synthesis of the antioxidant glutathione. v) Intermediates of the catabolism of 5 out of the 6 ketogenic amino acids were increased. vi) The levels of spermidine (a polyamine inducer of autophagy with anti-inflammatory effects) were decreased.

CONCLUSIONS

In ACLF, blood amino acids fueled protein and nucleotide synthesis required for the intense systemic inflammatory response. Ketogenic amino acids were extensively catabolized to produce energy substrates in peripheral organs, an effect that was insufficient because organs failed. Finally, the decrease in spermidine levels may cause a defect in autophagy contributing to the proinflammatory phenotype in ACLF.

LAY SUMMARY

Systemic inflammation and organ failures are hallmarks of acute-on-chronic liver failure (ACLF). Herein, we aimed to characterize the role of amino acids in these processes. The blood metabolome of patients with acutely decompensated cirrhosis, and particularly those with ACLF, reveals evidence of intense skeletal muscle catabolism. Importantly, amino acids (along with glucose), are used for intense anabolic, energy-consuming metabolism in patients with ACLF, presumably to support de novo nucleotide and protein synthesis in the activated innate immune system.

Metabolomic profiles of breath odor compounds for prognostic prediction in patients with acute-on-chronic liver failure: A pilot study

AIM

The aim of this study was to use a metabonomics approach to identify potential biomarkers of exhaled breath condensate (EBC) for predicting the prognosis of acute-on-chronic liver failure (ACLF).

METHODS

Using liquid chromatography mass spectrometry, EBC metabolites of ACLF patients surviving without liver transplantation (n = 57) and those with worse outcomes (n = 45), and controls (n = 15) were profiled from a specialized liver disease center in Beijing. The metabolites were used to identify candidate biomarkers, and the predicted performance of potential biomarkers was tested.

RESULTS

Forty-one metabolites, involving glycerophospholipid metabolism, sphingolipid metabolism, arachidonic acid metabolism, and amino acid metabolism, as candidate biomarkers for discriminating the different outcomes of ACLF were selected. A prognostic model was constructed by a panel of four metabolites including phosphatidylinositol [20:4(5Z,8Z,11Z,14Z)/13:0], phosphatidyl ethanolamine (12:0/22:0), L-metanephrine and ethylbenzene, which could predict the worse prognosis in ACLF patients with sensitivity (84.4%) and specificity (89.5%) (area under the receiver operating characteristic curve [AUC] = 0.859, 95% confidence interval [CI] = 0.787-0.931). Compared with Model for End-Stage Liver Disease (MELD) score (AUC = 0.639, 95% CI = 0.526-0.753) and MELD-sodium (MELD-Na) score (AUC = 0.692, 95% CI = 0.582-0.803), EBC-associated metabolite signature model could better predict worse outcomes in patients with ACLF (p < 0.05). Using the MELD-Na score and EBC metabolite signatures, a decision tree model was built for predicting the prognosis of ACLF identified on logistic regression analyses (AUC = 0.906, 95% CI = 0.846-0.965).

CONCLUSION

EBC metabolic signatures show promise as potential biomarkers for predicting worse prognosis of ACLF.

Mahuang Decoction Antagonizes Acute Liver Failure via Modulating Tricarboxylic Acid Cycle and Amino Acids Metabolism

Acute liver failure (ALF) is a serious clinical disorder with high fatality rates. Mahuang decoction (MHD), a well-known traditional Chinese medicine, has multiple pharmacological effects, such as anti-inflammation, anti-allergy, anti-asthma, and anti-hyperglycemia. In this study, we investigated the protective effect of MHD against ALF. In the lipopolysaccharide and D-galactosamine (LPS/D-GalN)-induced ALF mouse model, the elevated activities of the serum alanine and aspartate transaminases as well as the liver pathological damage were markedly alleviated by MHD. Subsequently, a metabolomics study based on the ultrahigh performance liquid chromatograph coupled with Q Exactive Orbitrap mass spectrometry was carried to clarify the therapeutic mechanisms of MHD against ALF. A total of 36 metabolites contributing to LPS/D-GalN-induced ALF were identified in the serum samples, among which the abnormalities of 27 metabolites were ameliorated by MHD. The analysis of metabolic pathways revealed that the therapeutic effects of MHD are likely due to the modulation of the metabolic disorders of tricarboxylic acid (TCA) cycle, retinol metabolism, tryptophan metabolism, arginine and proline metabolism, nicotinate and nicotinamide metabolism, phenylalanine metabolism, phenylalanine, tyrosine and tryptophan synthesis, as well as cysteine and methionine metabolism. This study demonstrated for the first time that MHD exerted an obvious protective effect against ALF mainly through the regulation of TCA cycle and amino acid metabolism, highlighting the importance of metabolomics to investigate the drug-targeted metabolic pathways.

Metabolomic Signatures of Autoimmune Hepatitis in the Development of Cirrhosis

Objectives: Autoimmune hepatitis (AIH) can progress into severe outcomes, i.e., decompensated cirrhosis, from remarkable and persistent inflammation in the liver. Considering the energy-expending nature of inflammation, we tried to define the metabolomics signatures of AIH to uncover the underlying mechanisms of cirrhosis development and its metabolic biomarkers. Methods: Untargeted metabolomics analysis was performed on sera samples from 79 AIH patients at the stages (phenotypes) of non-cirrhosis (n = 27), compensated cirrhosis (n = 22), and decompensated cirrhosis (n = 30). Pattern recognition was used to find unique metabolite fingerprints of cirrhosis with or without decompensation. Results: Out of the 294 annotated metabolites identified, 2 metabolic fingerprints were found associated with the development of cirrhosis (independent of the decompensated state, 42 metabolites) and the evolution of decompensated cirrhosis (out of 47 metabolites), respectively. The cirrhosis-associated fingerprints (eigenmetabolite) showed better capability to differentiate cirrhosis from non-cirrhosis patients than the aminotransferase-to-platelet ratio index. From the metabolic fingerprints, we found two pairs of metabolites (Mesobilirubinogen/6-Hydroxynicotinic acid and LysoPA(8:0/0:0)/7alpha-Hydroxycholesterol) calculated as ratio of intensities, which revealed robust abilities to identify cirrhosis or predict decompensated patients, respectively. These phenotype-related fingerprint metabolites featured fundamental energy supply disturbance along with the development of AIH cirrhosis and progression to decompensation, which was characterized as increased lipolysis, enhanced proteolysis, and increased glycolysis. Conclusions: Remodeling of metabolism to meet the liver inflammation-related energy supply is one of the key signatures of AIH in the development of cirrhosis and decompensation. Therefore, drug regulation metabolism has great potential in the treatment of AIH.

The systemic inflammation hypothesis: Towards a new paradigm of acute decompensation and multiorgan failure in cirrhosis

Acute decompensation (AD) of cirrhosis is defined by the development of ascites, hepatic encephalopathy and/or variceal bleeding. Ascites is traditionally attributed to splanchnic arterial vasodilation and left ventricular dysfunction, hepatic encephalopathy to hyperammonaemia, and variceal haemorrhage to portal hypertension. Recent large-scale European observational studies have shown that systemic inflammation is a hallmark of AD. Here we present a working hypothesis, the systemic inflammation hypothesis, suggesting that systemic inflammation through an impairment of the functions of one or more of the major organ systems may be a common theme and act synergistically with the traditional mechanisms involved in the development of AD. Systemic inflammation may impair organ system function through mechanisms which are not mutually exclusive. The first mechanism is a nitric oxide-mediated accentuation of the preexisting splanchnic vasodilation, resulting in the overactivation of the endogenous vasoconstrictor systems which elicit intense vasoconstriction and hypoperfusion in certain vascular beds, in particular the renal circulation. Second, systemic inflammation may cause immune-mediated tissue damage, a process called immunopathology. Finally, systemic inflammation may induce important metabolic changes. Indeed, systemic inflammatory responses are energetically expensive processes, requiring reallocation of nutrients (glucose, amino acids and lipids) to fuel immune activation. Systemic inflammation also inhibits nutrient consumption in peripheral (non-immune) organs, an effect that may provide one mechanism of reallocation and prioritisation of metabolic fuels for inflammatory responses. However, the decrease in nutrient consumption in peripheral organs may result in decreased mitochondrial production of ATP (energy) and subsequently impaired organ function.

Balance between macrophage migration inhibitory factor and sCD74 predicts outcome in patients with acute decompensation of cirrhosis

Background & Aims

Macrophage migration inhibitory factor (MIF) is an inflammatory cytokine and an important regulator of innate immune responses. We hypothesised that serum concentrations of MIF are associated with disease severity and outcome in patients with decompensated cirrhosis and acute-on-chronic liver failure (ACLF).

Methods

Circulating concentrations of MIF and its soluble receptor CD74 (sCD74) were determined in sera from 292 patients with acute decompensation of cirrhosis defined as new onset or worsening of ascites requiring hospitalisation. Of those, 78 (27%) had ACLF. Short-term mortality was assessed 90 days after inclusion.

Results

Although serum concentrations of MIF and sCD74 did not correlate with liver function parameters or ACLF, higher MIF (optimum cut-off >2.3 ng/ml) and lower concentrations of sCD74 (optimum cut-off <66.5 ng/ml) both indicated poorer 90-day transplant-free survival in univariate analyses (unadjusted hazard ratio [HR] 2.01 [1.26-3.22]; p = 0.004 for MIF; HR 0.59 [0.38-0.92]; p = 0.02 for sCD74) and after adjustment in multivariable models. Higher MIF concentrations correlated with surrogates of systemic inflammation (white blood cells, p = 0.005; C-reactive protein, p = 0.05) and were independent of genetic MIF promoter polymorphisms. Assessment of MIF plasma concentrations in portal venous blood and matched blood samples from the right atrium in a second cohort of patients undergoing transjugular intrahepatic portosystemic shunt insertion revealed a transhepatic MIF gradient with higher concentrations in the right atrial blood.

Conclusions

Serum concentrations of MIF and its soluble receptor CD74 predict 90-day transplant-free survival in patients with acute decompensation of cirrhosis. This effect was independent of liver function and genetic predispositions, but rather reflected systemic inflammation. Therefore, MIF and sCD74 represent promising prognostic markers beyond classical scoring systems in patients at risk of ACLF.

Lay summary

Inflammatory processes contribute to the increased risk of death in patients with cirrhosis and ascites. We show that patients with high serum levels of the inflammatory cytokine macrophage migration inhibitory factor (MIF) alongside low levels of its binding receptor sCD74 in blood indicate an increased mortality risk in patients with ascites. The cirrhotic liver is a relevant source of elevated circulating MIF levels.

Serum Levels of Metabolites Produced by Intestinal Microbes and Lipid Moieties Independently Associated With Acute-on-Chronic Liver Failure and Death in Patients With Cirrhosis

BACKGROUND & AIMS

Inpatients with cirrhosis have high rates of acute-on-chronic failure (ACLF) development and high mortality within 30 days of admission to the hospital. Better biomarkers are needed to predict these outcomes. We performed metabolomic analyses of serum samples from patients with cirrhosis at multiple centers to determine whether metabolite profiles might identify patients at high risk for ACLF and death.

METHODS

We performed metabolomic analyses, using liquid chromatography, of serum samples collected at time of admission to 12 North American tertiary hepatology centers from 602 patients in the North American Consortium for the Study of End-Stage Liver Disease sites from 2015 through 2017 (mean age, 56 years; 61% men; mean model for end-stage liver disease score, 19.5). We performed analysis of covariance, adjusted for model for end-stage liver disease at time of hospital admission, serum levels of albumin and sodium, and white blood cell count, to identify metabolites that differed between patients who did vs did not develop ACLF and patients who did vs did not die during hospitalization and within 30 days. We performed random forest analysis to identify specific metabolite(s) that were associated with outcomes and area under the curve (AUC) analyses to analyze them in context of clinical parameters. We analyzed microbiomes of stool samples collected from 133 patients collected at the same time and examined associations with serum metabolites.

RESULTS

Of the 602 patients analyzed, 88 developed ACLF (15%), 43 died in the hospital (7%), and 72 died within 30 days (12%). Increased levels of compounds of microbial origin (aromatic compounds, secondary or sulfated bile acids, and benzoate) and estrogen metabolites, as well as decreased levels of phospholipids, were associated with development of ACLF, inpatient, and 30-day mortality and were also associated with fecal microbiomes. Random forest analysis and logistic regression showed that levels of specific microbially produced metabolites identified patients who developed ACLF with an AUC of 0.84 (95% confidence interval [CI] 0.78-0.88; P = .001), patients who died while in the hospital with an AUC of 0.81 (95% CI 0.74-0.85; P = .002), and patients who died within 30 days with an AUC of 0.77 (95% CI 0.73-0.81; P = .02). The metabolites were significantly additive to clinical parameters for predicting these outcomes. Metabolites associated with outcomes were also correlated with microbiomes of stool samples.

CONCLUSIONS

In an analysis of serum metabolites and fecal microbiomes of patients hospitalized with cirrhosis at multiple centers, we associated metabolites of microbial origin and lipid moieties with development of ACLF and death as an inpatient or within 30 days, after controlling for clinical features.

pCLIF-SOFA is a reliable outcome prognostication score of critically ill children with cirrhosis: an ESPNIC multicentre study

Background and aims

Data on outcome of critically ill children with cirrhosis are scarce. We aimed to evaluate the prognostic accuracy of sequential organs scoring systems in children with cirrhosis admitted to Paediatric Intensive Care Units (PICU).

Methods

We performed a multicentre retrospective analysis of children with cirrhosis admitted into four European PICUs between 2011 and 2016. Investigators were members of the ESPNIC liver failure and support working group. Paediatric End-Stage Liver Disease (PELD) and paediatric chronic liver failure sequential organ failure assessment score (pCLIF-SOFA) diagnostic accuracy for 28- and 60-day liver transplantation, 28-day mortality and 60-day composite outcome (ie. death or liver transplantation) were tested.

Results

One-hundred-and-thirty children were included. The main causes for PICU admission were acute-on-chronic liver failure (ACLF), gastrointestinal bleeding and sepsis. Twenty-nine percent died and 22.3% were transplanted by day-60 after PICU admission. On multivariable analysis, pCLIF-SOFA was the only predictor of mortality at day-28 and of composite outcome. Both pCLIF-SOFA and ACLF were independently associated with emergent liver transplantation. The pCLIF-SOFA score higher than 9 well predicted a 28-day mortality with a sensitivity of 87.8% and a specificity of 77.3%. A pCLIF-SOFA score higher than 7 was independently associated with liver transplantation on day-60. Stage 3 AKI assessed with KDIGO classification was significantly associated with 28-day mortality.

Conclusions

Half of critically ill cirrhotic children admitted to PICU either died or were transplanted within the initial 28-day period. On admission pCLIF-SOFA score accurately identify patients transplanted at day-28 and day-60 to those alive without LT and is associated with 28-day mortality and composite outcome at day-60.

Modeling tissue-relevant Caenorhabditis elegans metabolism at network, pathway, reaction, and metabolite levels

Metabolism is a highly compartmentalized process that provides building blocks for biomass generation during development, homeostasis, and wound healing, and energy to support cellular and organismal processes. In metazoans, different cells and tissues specialize in different aspects of metabolism. However, studying the compartmentalization of metabolism in different cell types in a whole animal and for a particular stage of life is difficult. Here, we present MEtabolic models Reconciled with Gene Expression (MERGE), a computational pipeline that we used to predict tissue-relevant metabolic function at the network, pathway, reaction, and metabolite levels based on single-cell RNA-sequencing (scRNA-seq) data from the nematode Caenorhabditis elegans. Our analysis recapitulated known tissue functions in C. elegans, captured metabolic properties that are shared with similar tissues in human, and provided predictions for novel metabolic functions. MERGE is versatile and applicable to other systems. We envision this work as a starting point for the development of metabolic network models for individual cells as scRNA-seq continues to provide higher-resolution gene expression data.

Acute-on-chronic liver failure: Definitions, pathophysiology and principles of treatment

The term acute-on-chronic liver failure (ACLF) defines an abrupt and life-threatening worsening of clinical conditions in patients with cirrhosis or chronic liver disease. In recent years, different definitions and diagnostic criteria for the syndrome have been proposed by the major international scientific societies. The main controversies relate to the type of acute insult (specifically hepatic or also extrahepatic), the stage of underlying liver disease (cirrhosis or chronic hepatitis) and the concomitant extrahepatic organ failure(s) that should be considered in the definition of ACLF. Therefore, different severity criteria and prognostic scores have been proposed and validated. Current evidence shows that the pathophysiology of ACLF is closely associated with an intense systemic inflammation sustained by circulating pathogen-associated molecular patterns and damage-associated molecular patterns. The development of organ failures may be a result of a combination of tissue hypoperfusion, direct immune-mediated damage and mitochondrial dysfunction. Management of ACLF is currently based on the supportive treatment of organ failures, mainly in an intensive care setting. For selected patients, liver transplantation is an effective treatment that offers a good long-term prognosis. Future studies on potential mechanistic treatments that improve patient survival are eagerly awaited.

Explorative study of serum biomarkers of liver failure after liver resection

Conventional biochemical markers have limited usefulness in the prediction of early liver dysfunction. We, therefore, tried to find more useful liver failure biomarkers after liver resection that are highly sensitive to internal and external challenges in the biological system with a focus on liver metabolites. Twenty pigs were divided into the following 3 groups: sham operation group (n = 6), 70% hepatectomy group (n = 7) as a safety margin of resection model, and 90% hepatectomy group (n = 7) as a liver failure model. Blood sampling was performed preoperatively and at 1, 6, 14, 30, 38, and 48 hours after surgery, and 129 primary metabolites were profiled. Orthogonal projection to latent structures-discriminant analysis revealed that, unlike in the 70% hepatectomy and sham operation groups, central carbon metabolism was the most significant factor in the 90% hepatectomy group. Binary logistic regression analysis was used to develop a predictive model for mortality risk following hepatectomy. The recommended variables were malic acid, methionine, tryptophan, glucose, and γ-aminobutyric acid. Area under the curve of the linear combination of five metabolites was 0.993 (95% confidence interval: 0.927–1.000, sensitivity: 100.0, specificity: 94.87). We proposed robust biomarker panels that can accurately predict mortality risk associated with hepatectomy.

Albumin in decompensated cirrhosis: new concepts and perspectives

The pathophysiological background of decompensated cirrhosis is characterised by a systemic proinflammatory and pro-oxidant milieu that plays a major role in the development of multiorgan dysfunction. Such abnormality is mainly due to the systemic spread of bacteria and/or bacterial products from the gut and danger-associated molecular patterns from the diseased liver triggering the release of proinflammatory mediators by activating immune cells. The exacerbation of these processes underlies the development of acute-on-chronic liver failure. A further mechanism promoting multiorgan dysfunction and failure likely consists with a mitochondrial oxidative phosphorylation dysfunction responsible for systemic cellular energy crisis. The systemic proinflammatory and pro-oxidant state of patients with decompensated cirrhosis is also responsible for structural and functional changes in the albumin molecule, which spoil its pleiotropic non-oncotic properties such as antioxidant, scavenging, immune-modulating and endothelium protective functions. The knowledge of these abnormalities provides novel targets for mechanistic treatments. In this respect, the oncotic and non-oncotic properties of albumin make it a potential multitarget agent. This would expand the well-established indications to the use of albumin in decompensated cirrhosis, which mainly aim at improving effective volaemia or preventing its deterioration. Evidence has been recently provided that long-term albumin administration to patients with cirrhosis and ascites improves survival, prevents complications, eases the management of ascites and reduces hospitalisations. However, variant results indicate that further investigations are needed, aiming at confirming the beneficial effects of albumin, clarifying its optimal dosage and administration schedule and identify patients who would benefit most from long-term albumin administration.

Blood metabolomics uncovers inflammation-associated mitochondrial dysfunction as a potential mechanism underlying ACLF

BACKGROUND & AIMS

Acute-on-chronic liver failure (ACLF), which develops in patients with cirrhosis, is characterized by intense systemic inflammation and organ failure(s). Because systemic inflammation is energetically expensive, its metabolic costs may result in organ dysfunction/failure. Therefore, we aimed to analyze the blood metabolome in patients with cirrhosis, with and without ACLF.

METHODS

We performed untargeted metabolomics using liquid chromatography coupled to high-resolution mass spectrometry in serum from 650 patients with AD (acute decompensation of cirrhosis, without ACLF), 181 with ACLF, 43 with compensated cirrhosis, and 29 healthy individuals.

RESULTS

Of the 137 annotated metabolites identified, 100 were increased in patients with ACLF of any grade, relative to those with AD, and 38 comprised a distinctive blood metabolite fingerprint for ACLF. Among patients with ACLF, the intensity of the fingerprint increased across ACLF grades, and was similar in patients with kidney failure and in those without, indicating that the fingerprint reflected not only decreased kidney excretion but also altered cell metabolism. The higher the ACLF-associated fingerprint intensity, the higher the plasma levels of inflammatory markers, tumor necrosis factor α, soluble CD206, and soluble CD163. ACLF was characterized by intense proteolysis and lipolysis; amino acid catabolism; extra-mitochondrial glucose metabolism through glycolysis, pentose phosphate, and D-glucuronate pathways; depressed mitochondrial ATP-producing fatty acid β-oxidation; and extra-mitochondrial amino acid metabolism giving rise to metabotoxins.

CONCLUSIONS

In ACLF, intense systemic inflammation is associated with blood metabolite accumulation and profound alterations in major metabolic pathways, in particular inhibition of mitochondrial energy production, which may contribute to the development of organ failures.

LAY SUMMARY

Acute-on-chronic liver failure (ACLF), which develops in patients with cirrhosis, is characterized by intense systemic inflammation and organ failure(s). Because systemic inflammation is energetically expensive, its metabolic costs may result in organ dysfunction/failure. We identified a 38-metabolite blood fingerprint specific for ACLF that revealed mitochondrial dysfunction in peripheral organs. This may contribute to organ failures.

Acute-on-chronic liver failure: definition, prognosis and management

Acute-on-chronic liver failure (ACLF) is a recently described entity in chronic liver disease defined by acute hepatic decompensation, organ failure and a high risk of short-term mortality (usually less than 4 weeks). This condition is distinct from acute liver failure and stable progression of cirrhosis in numerous ways, including triggering precipitant factors, systemic inflammation, rapid progression and a potential for recovery. While a clear definition of ACLF has been forwarded from a large European Consortium study, some heterogeneity remains in how patients present and the types of organ failure, depending on whether they are described in Asian or European studies. Active alcoholism, acute alcoholic hepatitis and infections are the most frequent precipitants for ACLF. Underpinning the pathophysiology of ACLF is a state of persistent inflammation and immune dysfunction, collectively driving a systematic inflammatory response syndrome and an increased propensity to sepsis. Prevention and early treatment of organ failure are key in influencing survival. Given increasing organ shortage and more marginal grafts, liver transplantation is a limited resource and emphasises the need for new therapies to improve ACLF outcomes. Recent data indicate that liver transplantation has encouraging outcomes even in patients with advanced ACLF if patients are carefully selected during the permissive window of clinical presentation. ACLF remains a significant challenge in the field of hepatology, with considerable research and resource being channelled to improve upon the definition, prognostication, treatment and unravelling of mechanistic drivers. This Review discusses updates in ACLF definition, prognosis and management.

Metabolic Signature of Hepatic Fibrosis: From Individual Pathways to Systems Biology

Hepatic fibrosis is a major cause of morbidity and mortality worldwide, as it ultimately leads to cirrhosis, which is estimated to affect up to 2% of the global population. Hepatic fibrosis is confirmed by liver biopsy, and the erroneous nature of this technique necessitates the search for noninvasive alternatives. However, current biomarker algorithms for hepatic fibrosis have many limitations. Given that the liver is the largest organ and a major metabolic hub in the body, probing the metabolic signature of hepatic fibrosis holds promise for the discovery of new markers and therapeutic targets. Regarding individual metabolic pathways, accumulating evidence shows that hepatic fibrosis leads to alterations in carbohydrate metabolism, as aerobic glycolysis is aggravated in activated hepatic stellate cells (HSCs) and the whole fibrotic liver; in amino acid metabolism, as Fischer’s ratio (branched-chain amino acids/aromatic amino acids) decreases in patients with hepatic fibrosis; and in lipid metabolism, as HSCs lose vitamin A-containing lipid droplets during transdifferentiation, and cirrhotic patients have decreased serum lipids. The current review also summarizes recent findings of metabolic alterations relevant to hepatic fibrosis based on systems biology approaches, including transcriptomics, proteomics, and metabolomics in vitro, in animal models and in humans.

The Plasma [Kynurenine]/[Tryptophan] Ratio and Indoleamine 2,3-Dioxygenase: Time for Appraisal

The plasma kynurenine to tryptophan ([Kyn]/[Trp]) ratio is frequently used to express or reflect the activity of the extrahepatic Trp-degrading enzyme indoleamine 2,3-dioxygenase (IDO). This ratio is increasingly used instead of measurement of IDO activity, which is often low or undetectable in immune and other cells under basal conditions, but is greatly enhanced after immune activation. The use of this ratio is valid in in vitro studies, eg, in cell cultures or isolated organs, but its ‘blanket’ use in in vivo situations is not, because of modulating factors, such as supply of nutrients; the presence of multiple cell types; complex structural and functional tissue arrangements; the extracellular matrix; and hormonal, cytokine, and paracrine interactions. Determinants other than IDO may therefore be involved in vivo. These are hepatic tryptophan 2,3-dioxygenase (TDO) activity and the flux of plasma-free Trp down the Kyn pathway. In addition, conditions leading to accumulation of Kyn, eg, inhibition of activities of Kyn monooxygenase and kynureninase, could lead to elevation of the aforementioned ratio. In this review, the origin of use of this ratio will be discussed, variations in extent of its elevation will be described, evidence against its indiscriminate use will be presented, and examining determinants other than IDO activity and their correlates will be proposed for future studies.

Establishment of prognostic scoring models for different etiologies of acute decompensation in hospitalized patients with cirrhosis

Objective

Acute decompensation (AD) in liver cirrhosis has high mortality. We assessed prognostic scoring models and established prediction models for different etiologies of AD.

Methods

This retrospective analysis included 732 patients hospitalized with acute decompensated cirrhosis without acute-on-chronic liver failure. We performed logistic regression analysis of risk factors for mortality associated with different etiologies, to establish predictive models.

Results

Patients with different etiologies, scored using different scoring systems and various impact factors, exhibited differences with respect to mortality. MELD, CLIF-C-AD, MELD-Na, and AARC-ACLF scores exhibited adequate predictive ability for mortality. Area under the receiver operating characteristic curve for 28-day mortality for MELD, CLIF-C-AD, MELD-Na, AARC-ACLF, and the newly developed AD scores was 0.663, 0.673, 0.657, 0.662, and 0.773, respectively, in the hepatitis B virus group (HBV-AD score =−5.51 + 0.07*WBC count (109/L) +0.7*AD sum+0.4*AARC-ACLF score); 0.731, 0.737, 0.735, 0.689, and 0.778, respectively, in the alcoholic liver disease group (ALD-AD score =−4.55 +0.08* WBC count (109/L) +1.34* AD sum); and 0.765, 0.767, 0.814, 0.720, and 0.814, respectively, in the Others group (OTHERS-AD score =−2.14 + 1.24*MELD-Na score +4.49*AD sum).

Conclusions

The newly developed scoring models for short-term mortality were superior to the other scoring systems in predicting prognosis of acute decompensated cirrhosis in hospitalized patients.

Dysfunctional Immune Response in Acute-on-Chronic Liver Failure: It Takes Two to Tango

Acute-on-chronic liver failure (ACLF) is characterized by the acute decompensation of cirrhosis associated with organ failure and high short-term mortality. The key event in the pathogenesis is a dysfunctional immune response arising from exacerbation of the two main immunological alterations already present in cirrhosis: systemic inflammation and immune cell paralysis. High-grade systemic inflammation due to predominant activation and dysregulation of the innate immune response leads to the massive release of cytokines. Recognition of acutely increased pathogen and damage-associated molecular patterns by specific receptors underlies its pathogenesis and contributes to tissue damage and organ failure. In addition, an inappropriate compensatory anti-inflammatory response over the course of ACLF, along with the exhaustion and dysfunction of both the innate and adaptive immune systems, leads to functional immune cell paralysis. This entails a high risk of infection and contributes to a poor prognosis. Therapeutic approaches seeking to counteract the immune alterations present in ACLF are currently under investigation.