Reduced monocyte HLA-DR expression: a novel biomarker of disease severity and outcome in acetaminophen-induced acute liver failure

Modeling and Simulation of Acetaminophen Pharmacokinetics and Hepatic Biomarkers After Overdoses of Extended-Release and Immediate-Release Formulations in Healthy Adults Using the Quantitative Systems Toxicology Software Platform DILIsym

Acetaminophen (APAP) has been formulated as immediate-, modified-, and extended-release tablets (APAP-IR, -MR, and -ER, respectively). However, there was concern that APAP-MR previously available in Europe could form a bezoar after a large overdose, leading to delayed absorption and atypical pharmacokinetics (PK) compared to APAP-IR, and that current treatment guidelines developed for APAP overdose to prevent severe hepatotoxicity are inappropriate for APAP-MR. In contrast, APAP-ER caplets available in the United States are designed with an IR layer and an erodible ER layer. Using modeling and simulation, predicted PK and hepatotoxicity biomarkers following various acute overdose and repeated supratherapeutic ingestion (RSTI) scenarios with APAP-IR and APAP-ER were compared to investigate the differences between these two formulations. The existing APAP-IR representation within DILIsym v8A, a quantitative systems toxicology model of drug-induced liver injury, was updated, and an APAP-ER model was developed, using newly acquired in vitro (e.g., tiny-TIMsg) and clinical data. The model and simulated populations (SimPops) representing healthy adults were extensively validated, before simulating PK and three clinically useful hepatic biomarkers after various overdose scenarios. On average, APAP exposure after acute overdose and RSTI in healthy adults was predicted to be slightly lower for APAP-ER compared to APAP-IR, partially due to lower APAP absorption for APAP-ER, while not markedly impacting the expected time course of APAP plasma concentrations. Similar hepatic biomarker profiles were predicted for both APAP formulations. Based on these results, the APAP overdose consensus treatment guidelines updated in 2023 are not further impacted by this report.

Individual mHLA-DR trajectories in the ICU as predictors of early infections following liver transplantation: a prospective observational study

BACKGROUND

Infections are a leading cause of early mortality after liver transplantation (LT). Prior to transplantation, cirrhosis-associated immune dysfunction significantly increases the risk of infection. This study investigated the potential of immune monitoring, with a focus on monocytic HLA-DR (mHLA-DR) expression, as a predictor of post-LT complications.

METHODS

We conducted a prospective study on 130 patients awaiting LT at Lyon University Hospital to assess mHLA-DR expression, lymphocyte subsets, and T-cell function before and after LT. Multivariate analysis and K-means longitudinal clustering were performed to explore the relationships between immune trajectories and clinical outcomes.

RESULTS

Among the 99 patients who underwent LT, 35.4% experienced infections early post-LT. No difference in outcome was found regarding lymphocyte count or function. Delayed mHLA-DR recovery (Day 7 < 11,000 AB/C) and pre-LT MELD scores > 30 emerged as independent infection risk factors, with ORs of 12.1 [4.4-38.2], p < 0.0001 and 4.9 [1.4-18.4], p = 0.01, respectively. Patients with delayed mHLA-DR restoration also had reduced one-year survival (77.8% versus 98.3%, p = 0.003). K-means clustering revealed three distinct mHLA-DR recovery profiles, with the slowest recovery group showing the poorest outcomes.

CONCLUSIONS

Our findings highlight mHLA-DR as an early predictor of post-LT infections. Monitoring post-LT immune function through mHLA-DR expression could guide individualized management strategies to improve outcomes. Trial registration The study was registered in the ClinicalTrials.gov registry: NCT03995537, date: June 20, 2019.

Decreased monocytic HLA-DR in patients with sepsis: Prediction of diagnosis, severity and prognosis

OBJECTIVE

Sepsis is characterized by high incidence and mortality rates, making early recognition and risk stratification critical for preventing delayed treatment and overtreatment. This study investigated the potential of monocytic (m) HLA-DR as a diagnostic and prognostic biomarker of sepsis.

METHODS

In this prospective study, we collected blood in EDTA-anticoagulated tubes within 48 h from patients diagnosed with sepsis or infection and analyzed the percentage of mHLA-DR in peripheral blood mononuclear cells, C-reactive protein, and procalcitonin within 2 h of collection. We gathered clinical and laboratory data, including sex, age, and comorbidities, calculated the number of dysfunctional organs and sequential organ failure assessment (SOFA) score, and recorded the survival status of patients with sepsis on the 30th day after admission.

RESULTS

mHLA-DR levels were lower in patients with sepsis (median 46.60 [interquartile range 23.86-66.51]%) than infection (75.44 [52.13-91.50]%). mHLA-DR could distinguish sepsis from infection with an area under the curve (AUC) of 0.724 (95 %CI 0.624-0.824). Decreased mHLA-DR levels have been found in septic patients with shock or secondary infections. mHLA-DR expression decreased with an increasing number of dysfunctional organs and higher SOFA score. In 30-day non-survivors, mHLA-DR levels were 26.94 (12.06-44.45)%, significantly lower than in survivors (55.20 [24.83-72.37]%). mHLA-DR predicted sepsis prognosis with an AUC of 0.750 (95 %CI 0.623-0.877). When the cut-off value was <52.29 %, the sensitivity and specificity of mHLA-DR for prognosis were 100 % and 52.83 %, respectively. The 30-day survival rate of septic patients with mHLA-DR ≥ 52.29 % was 6.798 (95 %CI 2.075-22.27) times higher than that of patients with mHLA-DR < 52.29 %.

CONCLUSION

mHLA-DR negatively correlates with the severity of sepsis and could be used as a diagnostic and prognostic biomarker for sepsis.

Development and validation of risk prediction model for bacterial infections in acute liver failure patients

Infections significantly increase mortality in acute liver failure (ALF) patients, and there are no risk prediction models for early diagnosis and treatment of infections in ALF patients. This study aims to develop a risk prediction model for bacterial infections in ALF patients to guide rational antibiotic therapy. The data of ALF patients admitted to the Second Hospital of Hebei Medical University in China from January 2017 to January 2022 were retrospectively analyzed for training and internal validation. Patients were selected according to the updated 2011 American Association for the Study of Liver Diseases position paper on ALF. Serological indicators and model scores were collected within 24 h of admission. New models were developed using the multivariate logistic regression analysis. An optimal model was selected by receiver operating characteristic (ROC) analysis, Hosmer-Lemeshow test, the calibration curve, the Brier score, the bootstrap resampling, and the decision curve analysis. A nomogram was plotted to visualize the results. A total of 125 ALF patients were evaluated and 79 were included in the training set. The neutrophil-to-lymphocyte ratio and sequential organ failure assessment (SOFA) were integrated into the new model as independent predictive factors. The new SOFA-based model outperformed other models with an area under the ROC curve of 0.799 [95% confidence interval (CI): 0.652-0.926], the superior calibration and predictive performance in internal validation. High-risk individuals with a nomogram score ≥26 are recommended for antibiotic therapy. The new SOFA-based model demonstrates high accuracy and clinical utility in guiding antibiotic therapy in ALF patients.

The burden and predictors of 30-day unplanned readmission in patients with acute liver failure: a national representative database study

BACKGROUND

Liver diseases were significant source of early readmission burden. This study aimed to evaluate the 30-day unplanned readmission rates, causes of readmissions, readmission costs, and predictors of readmission in patients with acute liver failure (ALF).

METHODS

Patients admitted for ALF from 2019 National Readmission Database were enrolled. Weighted multivariable logistic regression models were applied and based on Directed Acyclic Graphs. Incidence, causes, cost, and predictors of 30-day unplanned readmissions were identified.

RESULTS

A total of 3,281 patients with ALF were enrolled, of whom 600 (18.3%) were readmitted within 30 days. The mean time from discharge to early readmission was 12.6 days. The average hospital cost and charge of readmission were $19,629 and $86,228, respectively. The readmissions were mainly due to liver-related events (26.6%), followed by infection (20.9%). The predictive factors independently associated with readmissions were age, male sex (OR 1.227, 95% CI 1.023-1.472; P = 0.028), renal failure (OR 1.401, 95% CI 1.139-1.723; P = 0.001), diabetes with chronic complications (OR 1.327, 95% CI 1.053-1.672; P = 0.017), complicated hypertension (OR 1.436, 95% CI 1.111-1.857; P = 0.006), peritoneal drainage (OR 1.600, 95% CI 1.092-2.345; P = 0.016), etc. CONCLUSIONS: Patients with ALF are at relatively high risk of early readmission, which imposes a heavy medical and economic burden on society. We need to increase the emphasis placed on early readmission of patients with ALF and establish clinical strategies for their management.

Critical care management of acute liver failure

The management of acute liver failure (ALF) in modern hepatology intensive care units (ICU) has improved patient outcomes. Critical care management of hepatic encephalopathy, cerebral edema, fluid and electrolytes; prevention of infections and organ support are central to improved outcomes of ALF. In particular, the pathogenesis of encephalopathy is multifactorial, with ammonia, elevated intra-cranial pressure and systemic inflammation playing a central role. Although ALF remains associated with high mortality, the availability of supportive care, including organ failure support such as plasma exchange, timely mechanical ventilation or continuous renal replacement therapy, either conservatively manages patients with ALF or offers bridging therapy until liver transplantation. Thus, appropriate critical care management has improved the likelihood of patient recovery in ALF. ICU care interventions such as monitoring of cerebral edema, fluid status assessment and interventions for sepsis prevention, nutritional support and management of electrolytes can salvage a substantial proportion of patients. In this review, we discuss the key aspects of critical care management of ALF.

Prevalence, Risk Factors, and Impact of Bacterial or Fungal Infections in Acute Liver Failure Patients from India

BACKGROUND

We evaluated the prevalence, risk factors, and impact of bacterial/fungal infections in acute liver failure (ALF) patients.

METHODS

We analyzed clinical, biochemical, and microbiological data of ALF patients with and without bacterial/fungal infections admitted at an institute over the last 5 years.

RESULTS

We enrolled 143 patients, 50% males, median age 25 years, with acute viral hepatitis (32.2%), drug-induced injury (18.2%), and tropical illness (14%) as aetiologies of ALF. 110 patients (76.9%) developed bacterial/fungal infections [Bacterial infection: MDR: 70%, PDR: 7%, ESBL: 40%, CRE: 30%, CRAB: 26.6%, MDR-EF: 13.3% and fungal infection: 19 (17.3%)]. On univariable analysis, SIRS (33.6% vs.3%), ICU admission (78.2% vs. 45.5%), mechanical ventilation (88.2% vs. 51.5%), inotropes (39.1% vs. 6.1%), invasive catheters (91.8% vs. 39.4%), and prolonged catheterization (6 days vs. 0 days) were significant risk factors for infections (p < 0.05, each). In contrast, SIRS and catheterization independently predicted infection on multivariable regression. Organ failures [3 (2-4) vs. 1 (0-2)], grade-III-IV HE (67.3% vs. 33.3%), circulatory failure (39.1% vs. 6.1%), coagulopathy (INR > 2.5: 58.2% vs. 33.3%), renal injury (28.2% vs. 6.1%) (p < 0.05), MELD (32.9 ± 8.2 vs. 26.7 ± 8.3) and CPIS [3(2-4) vs. 2(0-2)] were higher in infected vs. non-infected patients (p < 0.001). 30-day survival was significantly lower in infected vs. non-infected patients (17.3% vs. 75.8%, p < 0.001), while no patient survived with fungal infections. Refractory septic shock was the commonest cause of mortality in patients.

CONCLUSIONS

Infections due to MDR organisms are high, fungal infections are fatal, and refractory septic shock is the dominant reason for mortality, implying bacterial and fungal infections as the major killer in ALF patients.

Liver Transplantation for Acute Liver Failure- Indication, Prioritization, Timing, and Referral

Acute liver failure (ALF) is a major success story in gastroenterology, with improvements in critical care and liver transplant resulting in significant improvements in patient outcomes in the current era compared to the dismal survival rates in the pretransplant era. However, the ever-increasing list of transplant candidates and limited organ pool makes judicious patient selection and organ use mandatory to achieve good patient outcomes and prevent organ wastage. Several scoring systems exist to facilitate the identification of patients who need a liver transplant and would therefore need an early referral to a specialized liver unit. The timing of the liver transplant is also crucial as transplanting a patient too early would lead to those who would recover spontaneously receiving an organ (wastage), and a late decision might result in the patient becoming unfit for transplant (delisted) or have an advanced disease which would result in poor post-transplant outcomes. The current article reviews the indications and contraindications of liver transplant in ALF patients, the various prognostic scoring systems, etiology-specific outcomes, prioritization and timing of referral.

Dysfunctions of Circulating Adaptive Immune Cells in End-Stage Liver Disease

End-stage liver disease (ESLD) from acute liver failure to compensated advanced chronic liver disease and decompensated cirrhosis at different stages (chronic decompensation, acute decompensation with or without acute-on-chronic liver failure) has high disease severity and poor patient outcome. Infection is a common complication in patients with ESLD and it is associated with a high mortality rate. Multiple mechanisms are involved in this marked susceptibility to infections, noticeably the inadequate immune response known as immune paresis, as part of cirrhosis-associated immune dysfunction (CAID). Specifically in the adaptive immune arm, lymphocyte impairments—including inadequate activation, reduced ability to secrete effector molecules and enhanced immune suppressive phenotypes—result in compromised systemic immune responses and increased risk of infections. This review summarises current knowledge of alterations in adaptive immune responsiveness and their underlying mechanisms in ESLD. Understanding these mechanisms is of crucial importance in the identification of potential therapeutic targets and applications of targeted treatments beyond antimicrobials, such as immunotherapy.

Reticuloendothelial activation and phenotypic alteration of peripheral monocytes with enhanced liver recruitment drive liver injury secondary to yellow phosphorus

BACKGROUND AND AIM

Monocytes and macrophages play a crucial role in the pathogenesis of acute liver failure (ALF). We aimed to study reticuloendothelial activation and its correlation with disease severity in commonly encountered yellow phosphorus (rodenticide)-induced hepatotoxicity patients. We also studied peripheral monocyte phenotype in a subset of patients.

METHODS

Reticuloendothelial activation markers were analyzed and correlated with disease severity score in a prospectively collected database of yellow phosphorus-related hepatoxicity patients between 2018 and 2021. In a prospective cohort of these patients and age-matched healthy controls, peripheral blood monocyte phenotyping was performed.

RESULTS

Reticuloendothelial activation markers were analyzed in 67 patients [Age: 23(12-64) years; median (range), men: 25, acute liver injury (ALI): 38, ALF: 29, model for end-stage liver disease (MELD) score: 28 (7-40)] of yellow phosphorus-induced hepatotoxicity. Serum ferritin (927; 10.3-34 807 ng/mL), sCD163 (4.59; 0.11-12.7 μg/mL), sCD25 (3050; 5.6-17 300 pg/mL) and plasma von Willebrand factor (423.5, 103-1106 IU/dL) were increased and showed significant correlation with liver disease severity assessed by MELD score (ρ = 0.29, ρ = 0.6, ρ = 0.56 and ρ = 0.46 respectively). Phenotyping and serum immune markers were performed in seven patients (M: 4; age: 27, 15-37 years; median, range; MELD score: 36, 21-40) and compared with eight healthy controls. Increase in classical monocytes and decrease in patrolling and intermediate monocyte subsets were observed in ALF cohort. HLA-DRlow CD163hi (immune exhaustion), CD64hi (immune complex-mediated response), and CCR2hi (liver homing) monocyte phenotype was noted.

CONCLUSION

Altered peripheral monocyte phenotype with enhanced liver homing and macrophage activation, suggests important role of innate immune activation, and provides a potential therapeutic target, in yellow phosphorus-induced hepatotoxicity.

Bacterial and fungal infections: a frequent and deadly complication among critically ill acute liver failure patients

BACKGROUND

Acute liver failure (ALF) is a rare but life-threatening condition mostly requiring intensive care unit (ICU) admission. ALF induces immune disorders and may promote infection acquisition. However, the clinical spectrum and impact on patients' prognosis remain poorly explored.

METHODS

We conducted a retrospective single-centre study on patients admitted for ALF to the ICU of a referral University Hospital from 2000 to 2021. Baseline characteristics and outcomes according to the presence of infection until day 28 were analysed. Risk factors for infection were determined using logistic regression. The impact of infection on 28-day survival was assessed using the proportional hazard Cox model.

RESULTS

Of the 194 patients enrolled, 79 (40.7%) underwent infection: community-acquired, hospital-acquired before ICU and ICU-acquired before/without and after transplant in 26, 23, 23 and 14 patients, respectively. Most infections were pneumonia (41.4%) and bloodstream infection (38.8%). Of a total of 130 microorganisms identified, 55 were Gram-negative bacilli (42.3%), 48 Gram-positive cocci (36.9%) and 21 were fungi (16.2%). Obesity (OR 3.77 [95% CI 1.18-14.40]; p = .03) and initial mechanical ventilation (OR 2.26 [95% CI 1.25-4.12]; p = .007) were independent factors associated with overall infection. SAPSII > 37 (OR 3.67 [95% CI 1.82-7.76], p < .001) and paracetamol aetiology (OR 2.10 [95% CI 1.06-4.22], p = .03) were independently associated with infection at admission to ICU. On the opposite, paracetamol aetiology was associated with lower risk of ICU-acquired infection (OR 0.37 [95% CI 0.16-0.81], p = .02). Patients with any type of infection had lower day 28 survival rates (57% versus 73%; HR 1.65 [1.01-2.68], p = .04). The presence of infection at ICU admission (p = .04), but not ICU-acquired infection, was associated with decreased survival.

CONCLUSIONS

The prevalence of infection is high in ALF patients which is associated with a higher risk of death. Further studies assessing the use of early antimicrobial therapy are needed.

Prognostic Scores in Acute Liver Failure Due to Viral Hepatitis

Viral infections are among the major causes of acute liver failure (ALF) worldwide. While the role of agents such as hepatitis A, B, C, D and E viruses in precipitating ALF are well known, improvements in serological assays have led to the detection of viral agents such as Epstein Barr virus, cytomegalovirus etc. as atypical causes of ALF. Despite the plethora of literature available on viral hepatitis and ALF, there is very limited large-scale epidemiologic data on the prevalence, risk factors of progression and outcomes in ALF of viral causes. This is important as viral infections remain the leading cause of ALF in the East and in developing countries, while the impact of viral ALF in the West has largely been ameliorated by effective vaccination and sanitization programs. This review focuses specifically on the available prognostic scores that aid in the management of ALF of viral etiologies while also briefly reviewing the current literature on newer viral agents known to cause ALF, risk factors of progression, outcomes and how management algorithms can be developed by incorporation of prognostic scoring systems for referral and transplant listing.

Combinatorial targeting of G-protein-coupled bile acid receptor 1 and cysteinyl leukotriene receptor 1 reveals a mechanistic role for bile acids and leukotrienes in drug-induced liver injury

BACKGROUND AND AIM

Drug-induced liver injury (DILI) is a common disorder that involves both direct liver cell toxicity and immune activation. The bile acid receptor, G-protein-coupled bile acid receptor 1 (GPBAR1; Takeda G-protein-coupled receptor 5 [TGR5]), and cysteinyl leukotriene receptor (CYSLTR) 1 are G-protein-coupled receptors activated by bile acids and leukotrienes, exerting opposite effects on cell-to-cell adhesion, inflammation, and immune cell activation. To investigate whether GPBAR1 and CYSLTR1 mutually interact in the development of DILI, we developed an orally active small molecule, CHIN117, that functions as a GPBAR1 agonist and CYSLTR1 antagonist.

APPROACH AND RESULTS

RNA-sequencing analysis of liver explants showed that acetaminophen (APAP) intoxication positively modulates the leukotriene pathway, CYSLTR1, 5-lipoxygenase, and 5-lipoxygenase activating protein, whereas GPBAR1 gene expression was unchanged. In mice, acute liver injury induced by orally dosing APAP (500 mg/kg) was severely exacerbated by Gpbar1 gene ablation and attenuated by anti-Cysltr1 small interfering RNA pretreatment. Therapeutic dosing of wild-type mice with CHIN117 reversed the liver damage caused by APAP and modulated up to 1300 genes, including 38 chemokines and receptors, that were not shared by dosing mice with a selective GPBAR1 agonist or CYSLTR1 antagonist. Coexpression of the two receptors was detected in liver sinusoidal endothelial cells (LSECs), monocytes, and Kupffer cells, whereas combinatorial modulation of CYSLTR1 and GPBAR1 potently reversed LSEC/monocyte interactions. CHIN117 reversed liver damage and liver fibrosis in mice administered CCl₄ .

CONCLUSIONS

By genetic and pharmacological approaches, we demonstrated that GPBAR1 and CYSLTR1 mutually interact in the development of DILI. A combinatorial approach designed to activate GPBAR1 while inhibiting CYSLTR1 reverses liver injury in models of DILI.

Low Baseline but Not Delta Cortisol Relates to 28-Day Transplant-Free Survival in Acute and Acute-on-Chronic Liver Failure

Background and Aims

The clinical, prognostic, and therapeutic impact of adrenal insufficiency in acute liver failure (ALF) and acute-on-chronic liver failure (ACLF) remains controversial and exact diagnostic criteria are lacking. We sought to determine the diagnostic and therapeutic value of cortisol measurement and glucocorticoid (GC) treatment in ALF and ACLF.

Methods

28-day transplant-free survival (TFS) was studied in relation to absolute cortisol concentrations and to GC treatment in ALF (n = 30) and ACLF (n = 34) patients. Cortisol concentrations and short synacthen test were assessed by chemiluminescence immunoassay and liquid chromatography-mass spectrometry. Clinicians decided independently on GC treatment. In relation, phenotypic and functional characteristics of circulating monocytes were assessed.

Results

In ALF, baseline cortisol concentrations <387 nmol/L predicted TFS (sensitivity 83%, specificity 53%). In ACLF, baseline cortisol <392 nmol/L correlated with TFS (sensitivity 80%, specificity 61%). In both, ALF and ACLF, GC treatment did not influence 28-day TFS in patients with low baseline cortisol. However, in patients with baseline cortisol exceeding 387 and 392 nmol/L, respectively, TFS was higher if they had been treated with GC. High baseline cortisol was associated with low HLA-DR expression on monocytes.

Conclusion

Our data suggest a prognostic value of baseline cortisol measurement in ALF and ACLF. Overall, strong activation of the hypothalamic-pituitary-adrenal axis indicated poor prognosis. Furthermore, baseline cortisol deserves prospective evaluation as a guide for GC treatment decision-making.

Generation of pro-and anti-inflammatory mediators after acetaminophen overdose in surviving and non-surviving patients

Acetaminophen (APAP) overdose causes liver injury in animals and humans. Although well-studied in animals, limited longitudinal data exist on cytokine release after APAP overdose in patients. The purpose of this study was to quantify concentrations of cytokines in APAP overdose patients to determine if early cytokine or complement measurements can distinguish between surviving and non-surviving patients. Plasma was obtained from healthy controls, APAP overdose patients with no increase in liver transaminases, and surviving and non-surviving APAP overdose patients with severe liver injury. Interleukin-10 (IL-10), and CC chemokine ligand-2 (CCL2, MCP-1) were substantially elevated in surviving and non-surviving patients, whereas IL-6 and CXC chemokine ligand-8 (CXCL8, IL-8) had early elevations in a subset of patients only with liver injury. Day 1 IL-10 and IL-6 levels, and Day 2 CCL2, levels correlated positively with survival. There was no significant increase in IL-1α, IL-1β or TNF-α in any patient during the first week after APAP. Monitoring cytokines such as CCL2 may be a good indicator of patient prognosis; furthermore, these data indicate the inflammatory response after APAP overdose in patients is not mediated by a second phase of inflammation driven by the inflammasome.

Management of Acute Liver Failure: Update 2022

Abbreviated pathogenesis and clinical course of the acute liver failure syndrome. The pathogenesis and clinical course of the syndrome of acute liver failure (ALF) differs depending upon the etiology of the primary liver injury. In turn, the severity of the liver injury and resulting synthetic failure is often the primary determinant of whether a patient is referred for emergency liver transplantation. Injuries by viral etiologies trigger the innate immune system via pathogen-associated molecular patterns (PAMPs), while toxin-induced (and presumably ischemia-induced) injuries do so via damage-associated molecular patterns (DAMPs). The course of the clinical syndrome further depends upon the relative intensity and composition of cytokine release, resulting in an early proinflammatory phenotype (SIRS) and later compensatory anti-inflammatory response phenotype (CARS). The outcomes of overwhelming immune activation are the systemic (extrahepatic) features of ALF (cardiovascular collapse, cerebral edema, acute kidney injury, respiratory failure, sepsis) which ultimately determine the likelihood of death.Acute liver failure (ALF) continues to carry a high risk of mortality or the need for transplantation despite recent improvements in overall outcomes over the past two decades. Optimal management begins with identifying that liver failure is indeed present and its etiology, since outcomes and the need for transplantation vary widely across the different etiologies. Most causes of ALF can be divided into hyperacute (ischemia and acetaminophen) and subacute types (other etiologies), based on time of evolution of signs and symptoms of liver failure; the former evolve in 3 to 4 days and the latter typically in 2 to 4 weeks. Both involve intense release of cytokines and hepatocellular contents into the circulation with multiorgan effects/consequences.Management involves optimizing fluid balance and cardiovascular support, including the use of continuous renal replacement therapy, vasopressors, and pulmonary ventilation. Early evaluation for liver transplantation is advised particularly for acetaminophen toxicity, which evolves so rapidly that delay is likely to lead to death.Vasopressor support, high-grade hepatic encephalopathy, and unfavorable (subacute) etiologies heighten the need for urgent listing for liver transplantation. Prognostic scores such as Kings Criteria, Model for End-Stage Liver Disease, and the Acute Liver Failure Group prognostic index take these features into account and provide reasonable but imperfect predictive accuracy. Future treatments may include liver support devices and/or agents that improve hepatocyte regeneration.

Whole Exome Sequencing Reveals Genetic Variants in HLA Class II Genes Associated With Transplant-free Survival of Indeterminate Acute Liver Failure

INTRODUCTION

Indeterminate acute liver failure (IND-ALF) is a rare clinical syndrome with a high mortality rate. Lacking a known etiology makes rapid evaluation and treatment difficult, with liver transplantation often considered as the only therapeutic option. Our aim was to identify genetic variants from whole exome sequencing data that might be associated with IND-ALF clinical outcomes.

METHODS

Bioinformatics analysis was performed on whole exome sequencing data for 22 patients with IND-ALF. A 2-tier approach was used to identify significant single-nucleotide polymorphisms (SNPs) associated with IND-ALF clinical outcomes. Tier 1 identified the SNPs with a higher relative risk in the IND-ALF population compared with those identified in control populations. Tier 2 determined the SNPs connected to transplant-free survival and associated with model for end-stage liver disease serum sodium and Acute Liver Failure Study Group prognostic scores.

RESULTS

Thirty-one SNPs were found associated with a higher relative risk in the IND-ALF population compared with those in controls, of which 11 belong to the human leukocyte antigen (HLA) class II genes but none for the class I. Further analysis showed that 5 SNPs: rs796202376, rs139189937, and rs113473719 of HLA-DRB5; rs9272712 of HLA-DQA1; and rs747397929 of IDO1 were associated with a higher probability of IND-ALF transplant-free survival. Using 3 selected SNPs, a model for the polygenic risk score was developed to predict IND-ALF prognoses, which are comparable with those by model for end-stage liver disease serum sodium and Acute Liver Failure Study Group prognostic scores.

DISCUSSION

Certain gene variants in HLA-DRB5, HLA-DQA1, and IDO1 were found associated with IND-ALF transplant-free survival. Once validated, these identified SNPs may help elucidate the mechanism of IND-ALF and assist in its diagnosis and management.

Chloride intercellular channel 3 suppression-mediated macrophage polarization: a potential indicator of poor prognosis of hepatitis B virus-related acute-on-chronic liver failure

Patients with hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) are characterized by immune paralysis and susceptibility to infections. Macrophages are important mediators of immune responses can be subclassified into two main phenotypes: classically activated and alternatively activated. However, few studies have investigated changes to macrophage polarization in HBV-related liver diseases. Therefore, we investigated the functional status of monocyte-derived macrophages (MDMs) from patients with mild chronic hepatitis B (n = 226), HBV-related compensated cirrhosis (n = 36), HBV-related decompensated cirrhosis (n = 40), HBV-ACLF (n = 62) and healthy controls (n = 10), as well as Kupffer cells (KCs) from patients with HBV-ACLF (n = 3). We found that during the progression of HBV-related liver diseases, the percentage of CD163⁺ CD206⁺ macrophages increased, while the percentage of CD80⁺ human leukocyte antigen-DR⁺ macrophages decreased significantly. MDMs and KCs mainly exhibited high CD163⁺ CD206⁺ expression in patients with HBV-ACLF, which predicted poor clinical outcome and higher liver transplantation rate. Transcriptome sequencing analysis revealed that chloride intracellular channel-3 (CLIC3) was reduced in patients with HBV-ACLF, indicating a poor prognosis. To further study the effect of CLIC3 on macrophage polarization, human monocytic THP-1 cell-derived macrophages were used. We found that classical and alternative macrophage activation occurred through nuclear factor kappa B (NF-κB) and phosphoinositide 3-kinase/protein kinase B pathways, respectively. CLIC3 suppression inhibited NF-κB activation and promoted the alternative activation. In conclusion, macrophage polarization gradually changed from classically activated to alternatively activated as HBV-related liver diseases progressed. Both CLIC3 suppression and increased alternatively activated macrophage percentage were potential indicators of the poor prognosis of patients with HBV-ACLF.

Macrophages as key regulators of liver health and disease

Macrophages are a heterogeneous population of innate immune cells and key cellular components of the liver. Hepatic macrophages consist of embryologically-derived resident Kupffer cells (KC), recruited monocyte-derived macrophages (MDM) and capsular macrophages. Both the diversity and plasticity of hepatic macrophage subsets explain their different functions in the maintenance of hepatic homeostasis and in injury processes in acute and chronic liver diseases. In this review, we assess the evidence for macrophage involvement in regulating both liver health and injury responses in liver diseases including acute liver injury (ALI), chronic liver disease (CLD) (including liver fibrosis) and hepatocellular carcinoma (HCC). In healthy livers, KC display critical functions such as phagocytosis, danger signal recognition, cytokine release, antigen processing and the ability to orchestrate immune responses and maintain immunological tolerance. However, in most liver diseases there is a striking hepatic MDM expansion, which orchestrate both disease progression and regression. Single-cell approaches have transformed our understanding of liver macrophage heterogeneity, dynamics, and functions in both human samples and preclinical models. We will further discuss the new insights provided by these approaches and how they are enabling high-fidelity work to specifically identify pathogenic macrophage subpopulations. Given the important role of macrophages in regulating injury responses in a broad range of settings, there is now a huge interest in developing new therapeutic strategies aimed at targeting macrophages. Therefore, we also review the current approaches being used to modulate macrophage function in liver diseases and discuss the therapeutic potential of targeting macrophage subpopulations as a novel treatment strategy for patients with liver disorders.

Plasma Exchange in Acute and Acute on Chronic Liver Failure

Liver failure in the context of acute (ALF) and acute on chronic liver failure (ACLF) is associated with high mortality in the absence of a liver transplant. For decades, therapeutic plasma exchange (TPE) is performed for the management of immune-mediated diseases. TPE has emerged as an attractive extracorporeal blood purification technique in patients with ALF and ACLF. The basic premise of using TPE is to remove the toxic substances which would allow recovery of native liver functions by facilitating liver regeneration. In recent years, encouraging data have emerged, suggesting the benefits of TPE in patients with liver failure. TPE has emerged as an attractive liver support device for the failing liver until liver transplantation or clinical recovery. The data in patients with ALF suggest routine use of high-volume TPE, while the data for such a strategy are less robust for patients with ACLF.

Liver transplantation in acute liver failure: Dilemmas and challenges

Acute liver failure (ALF) refers to a state of severe hepatic injury that leads to altered coagulation and sensorium in the absence of pre-existing liver disease. ALF has different causes, but the clinical characteristics are strikingly similar. In clinical practice, however, inconsistency in the definition of ALF worldwide and confusion regarding the existence of pre-existing liver disease raise diagnostic dilemmas. ALF mortality rates used to be over 80% in the past; however, survival rates on medical treatment have significantly improved in recent years due to a greater understanding of pathophysiology and advances in critical care management. The survival rates in acetaminophen-associated ALF have become close to the post-transplant survival rates. Given that liver transplantation (LT) is an expensive treatment that involves a major surgical operation in critically ill patients and lifelong immunosuppression, it is very important to select accurate patients who may benefit from it. Still, emergency LT remains a lifesaving procedure for many ALF patients. However, there is a lack of consistency in current prognostic models that hampers the selection of transplant candidates in a timely and precise manner. The other problems associated with LT in ALF are the shortage of graft, development of contraindications on the waiting list, vaguely defined delisting criteria, time constraints for pre-transplant evaluation, ethical concerns, and comparatively poor post-transplant outcomes in ALF. Therefore, there is a desperate need to establish accurate prognostic models and explore the roles of evolving adjunctive and alternative therapies, such as liver support systems, plasma exchange, stem cells, auxiliary LT, and so on, to enhance transplant-free survival and to fill the void created by the graft shortage.

Activated Hepatic Stellate Cells Induce Infiltration and Formation of CD163+ Macrophages via CCL2/CCR2 Pathway

Background: Activated hepatic stellate cells (aHSCs) regulate the function of immune cells during liver fibrosis. As major innate cells in the liver, macrophages have inducible plasticity. Nevertheless, the mechanisms through which aHSCs regulate macrophages' phenotype and function during liver fibrosis and cirrhosis remain unclear. In this study, we examined the immunoregulatory function of aHSCs during liver fibrosis and explored their role in regulating macrophage phenotype and function. Methods: A total of 96 patients with different stages of chronic hepatitis B-related liver fibrosis were recruited in the study. Metavir score system was used to evaluate the degree of fibrosis. The expression of hepatic CCL2 and M2 phenotype macrophage marker CD163 were detected by immunohistochemistry, and the relationship among hepatic CD163, CCL2, and fibrosis scores were also explored. In the in vitro model, the aHSCs isolated from human liver tissues and THP-1-derived M0-type macrophages (M0MΦ) were co-cultured to observe whether and how aHSCs regulate the phenotype and function of macrophages. To explore whether CCL2/CCR2 axis has a crucial role in macrophage phenotypic changes during liver fibrosis, we treated the M0MΦ with recombinant human CCL2 or its specific receptor antagonist INCB-3284. Furthermore, we used LX2 and TGF-β-activated LX2 to mimic the different activation statuses of aHSCs to further confirm our results. Results: In patients, the infiltration of M2 macrophages increased during the progression of liver fibrosis. Intriguingly, as a key molecule for aHSC chemotactic macrophage aggregation, CCL2 markedly up-regulated the expression of CD163 and CD206 on the macrophages, which was further confirmed by adding the CCR2 antagonist (INCB 3284) into the cell culture system. In addition, the TGF-β stimulated LX2 further confirmed that aHSCs up-regulate the expression of CD163 and CD206 on macrophages. LX2 stimulated with TGF-β could produce more CCL2 and up-regulate other M2 phenotype macrophage-specific markers, including IL-10, ARG-1, and CCR2 besides CD163 and CD206 at the gene level, indicating that the different activation status of aHSCs might affect the final phenotype and function of macrophages. Conclusions: The expression of the M2 macrophage marker increases during liver fibrosis progression and is associated with fibrosis severity. AHSCs can recruit macrophages through the CCL2/CCR2 pathway and induce M2 phenotypic transformation.

sTim-3 alleviates liver injury via regulation of the immunity microenvironment and autophagy

Liver failure (LF) is a monocyte/macrophage-mediated liver injury that has been associated with inflammatory mediators. However, the mechanism through which monocytes/macrophages regulate LF has not been fully elucidated. In this study, we investigated the role of soluble T-cell immunoglobulin domain and mucin domain-containing molecule-3 (sTim-3) in inhibition of release of inflammatory mediators. We further assess this role in protection against D-galactosamine (D-GalN)/lipopolysaccharide (LPS)-induced acute liver failure (ALF), via monocyte/macrophage regulation and autophagy induction in mice. Our findings indicate significantly higher plasma sTim-3 in acute-on-chronic liver failure (ACLF) group relative to other groups, with this trend associated with disease progression. Furthermore, infiltrated recombinant sTim-3 inhibited release of various inflammatory mediators, including cytokines and human high-mobility group box-1 (HMGB1), potentially via autophagy induction. Furthermore, H&E staining and the low levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in ALF mice, supported that recombinant sTim-3 effectively alleviated liver injury. Moreover, sTim-3 induced changes in monocyte/macrophage population in mice's liver or blood, which consequently caused a reduction in proinflammatory CD11bhiF4/80lo monocyte-derived macrophages and Ly-6C(+)CD11b(+) monocytes. Conversely, sTim-3 increased autophagy levels of hepatic CD11b(+) monocyte-derived macrophages and decreased apoptosis rate of CD11b (+) monocytes in the blood. Collectively, our findings demonstrated that sTim-3 alleviated inflammatory response and liver injury by promoting autophagy and regulating monocyte/macrophage function. This indicates its potential for future development of novel therapeutic strategies against LF.

Acetaminophen Oxidation and Inflammatory Markers - A Review of Hepatic Molecular Mechanisms and Preclinical Studies

Acetaminophen is a widely used analgesic for pain management, especially useful in chronic diseases, such as rheumatoid arthritis. However, easy access to this medicine has increased the occurrence of episodes of poisoning. Patients often develop severe liver damage, which may quickly lead to death. Consequently, numerous studies have been conducted to identify new biomarkers that allow the prediction of the degree of acetaminophen intoxication and thus intervene in a timely manner to save patients' lives. This review highlights the main mechanisms of the induction and progression of liver damage arising from acetaminophen poisoning. In addition, we have discussed the possibility of using new clinical biomarkers for detecting acetaminophen poisoning.

Regulation of macrophage activation in the liver after acute injury: Role of the fibrinolytic system

The liver functions, in part, to prevent exposure of the body to potentially harmful substances ingested in the diet. While it is highly efficient at accomplishing this, it is frequently prone to liver injury due to the biotransformation of xenobiotics into toxic metabolites. To counter this injury, the liver has evolved a unique capacity to rapidly and efficiently repair itself. Successful resolution of acute liver injury relies on hepatic macrophage populations that orchestrate the reparative response. After injury, Kupffer cells, the resident macrophages of the liver, become activated and secrete proinflammatory cytokines. These cytokines recruit other immune cells, including monocyte-derived macrophages, to the liver where they contribute to the repair process. Monocyte-derived macrophages traffic into the necrotic foci where they rapidly phagocytose dead cell debris. Simultaneous with this process, these cells change phenotype from a proinflammatory macrophage to a pro-restorative macrophage that produce pro-mitogenic growth factors and anti-inflammatory cytokines. Ultimately this process triggers resolution of inflammation, and along with proliferation of other hepatic cells, restores the liver architecture and function. While the mechanisms regulating specific macrophage functions during repair remain to be elucidated, recent studies indicate a key role for the fibrinolytic system in coordinating macrophage function during repair. In this review, we will highlight the function and role of hepatic macrophages in repair after acute liver injury, and will discuss the role of the fibrinolytic enzyme, plasmin, in regulation of these various processes.

Effects of perioperative transcutaneous electrical acupoint stimulation on monocytic HLA-DR expression in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass: study protocol for a double-blind randomized controlled trial

BACKGROUND

Cardiac surgery involving cardiopulmonary bypass (CPB) is known to be associated with a transient postoperative immunosuppression. When severe and persistent, this immune dysfunction predisposes patients to infectious complications, which contributes to a prolonged stay in the intensive care unit (ICU), and even mortality. Effective prevention and treatment methods are still lacking. Recent studies revealed that acupuncture-related techniques, such as electroacupuncture and transcutaneous electrical acupoint stimulation (TEAS), are able to produce effective cardioprotection and immunomodulation in adult and pediatric patients undergoing cardiac surgery with CPB, which leads to enhanced recovery. However, whether perioperative application of TEAS, a non-invasive technique, is able to improve immunosuppression of the patients with post-cardiosurgical conditions is unknown. Thus, as a preliminary study, the main objective is to evaluate the effects of TEAS on the postoperative expression of monocytic human leukocyte antigen (-D related) (mHLA-DR), a standardized "global" biomarker of injury or sepsis-associated immunosuppression, in patients receiving on-pump coronary artery bypass grafting (CABG).

METHODS

This study is a single-center clinical trial. The 88 patients scheduled to receive CABG under CPB will be randomized into two groups: the group receiving TEAS, and the group receiving transcutaneous acupoint pseudo-electric stimulation (Sham TEAS). Expression of mHLA-DR serves as a primary endpoint, and other laboratory parameters (e.g., interleukin [IL]-6, IL-10) and clinical outcomes (e.g., postoperative infectious complications, ICU stay time, and mortality) as the secondary endpoints. In addition, immune indicators, such as high mobility group box 1 protein and regulatory T cells will also be measured.

DISCUSSION

The current study is a preliminary monocentric clinical trial with a non-clinical primary endpoint, expression of mHLA-DR, aiming at determining whether perioperative application of TEAS has a potential to reverse CABG-associated immunosuppression. Although the immediate clinical impact of this study is limited, its results would inform further large-sample clinical trials using relevant patient-centered clinical outcomes as primary endpoints.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02933996. Registered on 13 October 2016.

Intensive Care Management of Acute Liver Failure: Considerations While Awaiting Liver Transplantation

Acute liver failure is a unique clinical phenomenon characterized by abrupt deterioration in liver function and altered mentation. The development of high-grade encephalopathy and multisystem organ dysfunction herald poor prognosis. Etiologic-specific treatments and supportive measures are routinely employed; however, liver transplantation remains the only chance for cure in those who do not spontaneously recover. The utility of artificial and bioartificial assist therapies as supportive care-to allow time for hepatic recovery or as a bridge to liver transplantation-has been examined but studies have been small, with mixed results. Given the severity of derangements, intensive critical care is needed to successfully bridge patients to transplant, and evaluation of candidates occurs rapidly in parallel with serial reassessments of operative fitness. Psychosocial assessment is often suboptimal and relative contraindications to transplant, such as ventilator-dependence may be overlooked. While often employed to guide evaluation, no single prognostic model discriminates those who will spontaneously recover and those who will require transplant. The purpose of this review will be to summarize approaches in critical care, prognostic modeling, and medical evaluation of the acute liver failure transplant candidate.

Incorporation of dynamic segmented neutrophil-to-monocyte ratio with leukocyte count for sepsis risk stratification

The association between sepsis and segmented neutrophil-to-monocyte (SeMo) ratio is unclear. We postulated that an increase in dynamic SeMo ratio measurement can be applied in risk stratification. This retrospective study included 727 consecutive sepsis patients in medical intensive care units (ICUs), including a subpopulation of 153 patients. According to the leukocyte (white blood cell, WBC) count on day 3 (normal range, between 4,000/µL and 12,000/µL) and delta SeMo (value of SeMo ratio on day 3 minus value of SeMo ratio on day 1; normal delta SeMo, <7), patients were grouped into 3 (delta SeMo & WBC tool). The survival lines separated significantly with hazard ratios of 1.854 (1.342–2.560) for the delta SeMo or WBC abnormal group and 2.860 (1.849–4.439) for the delta SeMo and WBC abnormal group compared to the delta SeMo and WBC normal group. Delta SeMo & WBC tool and delta sequential organ failure assessment (SOFA) tool performed better than the other tools (delta SeMo, delta WBC, day 3 WBC, and day 1 WBC). Severity in delta SeMo & WBC tool and delta SeMo tool reflected the immune dysfunction score, cytokine expression, and human leukocyte antigen D-related monocyte expression on day 1 and day 3. There was correspondence between delta SOFA and delta WBC and between delta SeMo and delta cytokine expression. Incorporation of dynamic SeMo ratio with WBC count provides risk stratification for sepsis patients admitted in the ICU.

CD8+T cells from patients with cirrhosis display a phenotype that may contribute to cirrhosis-associated immune dysfunction

BACKGROUND

Cirrhosis-associated immune dysfunction (CAID) contributes to high sepsis risk in patients with chronic liver disease. Various innate and; to a lesser extent; adaptive immune dysfunctions have been described as contributors to CAID leading to immune-paresis and impaired anti-microbial response in cirrhosis. In this study, we examined the phenotype of CD8⁺T cells in chronic liver disease with the aim to evaluate changes that might contribute to impaired immune responses.

METHODS

Sixty patients with cirrhosis were prospectively recruited for this study. CD8⁺T cells from peripheral blood, ascites and liver explants were characterized using flow cytometry and immunohistochemistry, respectively. The transcriptional signature of flow-sorted HLA-DR⁺CD8⁺T cells was performed using Nanostring™ technology. HLA-DR⁺CD8⁺T cells interactions with PBMCs and myeloid cells were tested in vitro.

FINDINGS

Peripheral CD8⁺T cells from cirrhotic patients displayed an altered phenotype characterized by high HLA-DR and TIM-3 surface expression associated with concomitant infections and disease severity, respectively. Paired peritoneal CD8⁺T cells expressed more pronounced levels of HLA-DR and PD-1 compared to peripheral CD8⁺T cells. HLA-DR⁺CD8⁺T cells were enriched in cirrhotic livers compared to controls. TIM-3, CTLA-4 and PD-1 levels were highly expressed on HLA-DR⁺CD8⁺T cells and co-expression of HLA-DR and PD1 was higher in patients with poor disease outcomes. Genes involved in cytokines production and intracellular signalling pathways were strongly down-regulated in HLA-DR⁺CD8⁺T cells. In comparison to their HLA-DR^- counterparts, HLA-DR⁺CD8⁺T cells promoted less proliferation of PBMCs and induced phenotypic and functional dysfunctions in monocytes and neutrophils in vitro.

INTERPRETATION

In patients with cirrhosis, CD8⁺T cells display a phenotypic, functional and transcriptional profile which may contribute to CAID. FUND: This work was supported by Medical Research Council, the Rosetrees Charitable Trust, Robert Tournut 2016 grant (Sociéte Nationale Française de GastroEntérologie), Gilead® sciences, and NIHR Imperial Biomedical Research Centre.

CD8+T cells from patients with cirrhosis display a phenotype that may contribute to cirrhosis-associated immune dysfunction

BACKGROUND

Cirrhosis-associated immune dysfunction (CAID) contributes to high sepsis risk in patients with chronic liver disease. Various innate and; to a lesser extent; adaptive immune dysfunctions have been described as contributors to CAID leading to immune-paresis and impaired anti-microbial response in cirrhosis. In this study, we examined the phenotype of CD8+T cells in chronic liver disease with the aim to evaluate changes that might contribute to impaired immune responses.

METHODS

Sixty patients with cirrhosis were prospectively recruited for this study. CD8+T cells from peripheral blood, ascites and liver explants were characterized using flow cytometry and immunohistochemistry, respectively. The transcriptional signature of flow-sorted HLA-DR+CD8+T cells was performed using Nanostring™ technology. HLA-DR+CD8+T cells interactions with PBMCs and myeloid cells were tested in vitro.

FINDINGS

Peripheral CD8+T cells from cirrhotic patients displayed an altered phenotype characterized by high HLA-DR and TIM-3 surface expression associated with concomitant infections and disease severity, respectively. Paired peritoneal CD8+T cells expressed more pronounced levels of HLA-DR and PD-1 compared to peripheral CD8+T cells. HLA-DR+CD8+T cells were enriched in cirrhotic livers compared to controls. TIM-3, CTLA-4 and PD-1 levels were highly expressed on HLA-DR+CD8+T cells and co-expression of HLA-DR and PD1 was higher in patients with poor disease outcomes. Genes involved in cytokines production and intracellular signalling pathways were strongly down-regulated in HLA-DR+CD8+T cells. In comparison to their HLA-DR- counterparts, HLA-DR+CD8+T cells promoted less proliferation of PBMCs and induced phenotypic and functional dysfunctions in monocytes and neutrophils in vitro.

INTERPRETATION

In patients with cirrhosis, CD8+T cells display a phenotypic, functional and transcriptional profile which may contribute to CAID. FUND: This work was supported by Medical Research Council, the Rosetrees Charitable Trust, Robert Tournut 2016 grant (Sociéte Nationale Française de GastroEntérologie), Gilead® sciences, and NIHR Imperial Biomedical Research Centre.

The CD14+HLA-DRlo/neg Monocyte: An Immunosuppressive Phenotype That Restrains Responses to Cancer Immunotherapy

Recent successes in cancer immunotherapy have been tempered by sub-optimal clinical responses in the majority of patients. The impaired anti-tumor immune responses observed in these patients are likely a consequence of immune system dysfunction contributed to by a variety of factors that include, but are not limited to, diminished antigen presentation/detection, leukopenia, a coordinated network of immunosuppressive cell surface proteins, cytokines and cellular mediators. Monocytes that have diminished or no HLA-DR expression, called CD14⁺HLA-DR^lo/neg monocytes, have emerged as important mediators of tumor-induced immunosuppression. These cells have been grouped into a larger class of suppressive cells called myeloid derived suppressor cells (MDSCs) and are commonly referred to as monocytic myeloid derived suppressor cells. CD14⁺HLA-DR^lo/neg monocytes were first characterized in patients with sepsis and were shown to regulate the transition from the inflammatory state to immune suppression, ultimately leading to immune paralysis. These immunosuppressive monocytes have also recently been shown to negatively affect responses to PD-1 and CTLA-4 checkpoint inhibition, CAR-T cell therapy, cancer vaccines, and hematopoietic stem cell transplantation. Ultimately, the goal is to understand the role of these cells in the context of immunosuppression not only to facilitate the development of targeted therapies to circumvent their effects, but also to potentially use them as a biomarker for understanding disparate responses to immunotherapeutic regimens. Practical aspects to be explored for development of CD14⁺HLA-DR^lo/neg monocyte detection in patients are the standardization of flow cytometric gating methods to assess HLA-DR expression, an appropriate quantitation method, test sample type, and processing guidances. Once detection methods are established that yield consistently reproducible results, then further progress can be made toward understanding the role of CD14⁺HLA-DR^lo/neg monocytes in the immunosuppressive state.

Hepatoprotective effects and structure-activity relationship of five flavonoids against lipopolysaccharide/d-galactosamine induced acute liver failure in mice

Acute liver failure (ALF) is a distinct clinical syndrome with high mortality and characterized by metabolic derangements, neurological complication, and multiple failures. Flavonoids exert great biological properties on anti-oxidation, anti-inflammation, and anti-apoptosis. After lipopolysaccharide (LPS)/d-galactosamine (d-GalN) administration, five flavonoids inhibited oxidative activities with reducing nitric oxide synthase (iNOS), malondialdehyde (MDA), and improving catalase (CAT), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), nuclear factor erythroid-derived 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1). They reduced the serum levels of alanine and aspartate aminotransferase (ALT, AST) and pro-inflammatory cytokines, prevented the phosphorylation of IKK, IκBα, and NF-κB/p65 in the NF-κB signaling pathway. Additionally five flavonoids inhibited hepatocyte apoptosis through increasing Bcl-2/Bax ratio and suppressing the Caspase family proteins. Chrysin, luteolin, apigenin, hesperetin and 3', 4'-dimethoxy hesperetin have apparently hepato-protective effects against ALF induced by LPS/d-GalN. The study found, the C2C3 double bond at A ring, and the hydroxyl group of C3' or C4' at B ring increased the protective activities, however, the effect of hydroxymethylation at C3' and C4' was reversed. In addition, apigenin has good hepatoprotective effects and potential as a promising therapeutic agent for ALF in clinical application.

Neurological Recovery After Recovery From Acute Liver Failure: Is it Complete?

Neurologic dysfunction characterised by Hepatic Encephalopathy (HE) and cerebral oedema are the most dramatic presentations of Acute Liver Failure (ALF) and signify poor outcome. Improved critical care and wider availability of emergency Liver Transplantation (LT) has improved survivability in ALF. In most cases absence of clinically overt encephalopathy after spontaneous recovery from ALF or after LT is thought to indicate complete neurologic recovery. Recent data suggests that neurologic recovery may not always be complete. Instances of persistent neurologic dysfunction as well as neuropsychiatric abnormalities are now being recognised and warrant active follow up of these patients. Although evidences irreversible neurologic damage is uncommon after ALF, neuropsychiatric disturbances are not uncommon. Complex pathogenesis is involved in neurocognitive disorders seen after many other conditions including LT that require critical care. Structural damage and persistent neurological abnormalities seen after ALF are more likely to be related to cerebral edema, raised intracranial tension and cerebral hypoxemia, while neurocognitive dysfunctions may be a part of a wider spectrum of disorders commonly seen among those who recover from any critical illness.

The Role of Monocytes and Macrophages in Acute and Acute-on-Chronic Liver Failure

Acute and acute-on-chronic liver failure (ALF and ACLF), though distinct clinical entities, are considered syndromes of innate immune dysfunction. Patients with ALF and ACLF display evidence of a pro-inflammatory state with local liver inflammation, features of systemic inflammatory response syndrome (SIRS) and vascular endothelial dysfunction that drive progression to multi-organ failure. In an apparent paradox, these patients are concurrently immunosuppressed, exhibiting acquired immune defects that render them highly susceptible to infections. This paradigm of tissue injury succeeded by immunosuppression is seen in other inflammatory conditions such as sepsis, which share poor outcomes and infective complications that account for high morbidity and mortality. Monocyte and macrophage dysfunction are central to disease progression of ALF and ACLF. Activation of liver-resident macrophages (Kupffer cells) by pathogen and damage associated molecular patterns leads to the recruitment of innate effector cells to the injured liver. Early monocyte infiltration may contribute to local tissue destruction during the propagation phase and results in secretion of pro-inflammatory cytokines that drive SIRS. In the hepatic microenvironment, recruited monocytes mature into macrophages following local reprogramming so as to promote resolution responses in a drive to maintain tissue integrity. Intra-hepatic events may affect circulating monocytes through spill over of soluble mediators and exposure to apoptotic cell debris during passage through the liver. Hence, peripheral monocytes show numerous acquired defects in acute liver failure syndromes that impair their anti-microbial programmes and contribute to enhanced susceptibility to sepsis. This review will highlight the cellular and molecular mechanisms by which monocytes and macrophages contribute to the pathophysiology of ALF and ACLF, considering both hepatic inflammation and systemic immunosuppression. We identify areas for further research and potential targets for immune-based therapies to treat these devastating conditions.

Large-scale high-density culture of hepatocytes in a liver microsystem with mimicked sinusoid blood flow

In vitro engineering of liver tissue is a rapidly developing field for various biomedical applications. However, liver tissue culture is currently performed on only a small scale with a low density of hepatocytes. In this study, a simple design was introduced in a liver microsystem to enhance the transport of nutrients (e.g., oxygen and glucose) for the three-dimensional large-scale, high-density culture of hepatocytes. In this design, convection across the cell culture zone was generated to mimic sinusoid blood flow (SBF) based on the pressure difference between two fluids flowing in a countercurrent manner on either side of the cell culture zone. First, the distributions of living and dead cells in different culture subzones under various perfusion flow rates were observed, analysed, and compared. Then, the enhanced transport of nutrients was experimentally validated in relation to the viability of cells and theoretically explained by comparing the fluid velocity and oxygen concentration distribution in the cell culture zone in counterflow and coflow modes. Finally, the functions of the SBF-mimicked liver microsystem were assessed on the basis of specific metabolites, synthesized proteins, and bilirubin detoxification of hepatocytes, with collagen and alginate as extracellular matrices. Under this design, the density of hepatocytes cultured at the 3-mm-thickness scale reached ~7 × 10⁷  cells/ml on Day 7, and the metabolism and detoxification functions of the cells worked well. In addition, a liver rope-like structure and sphere-like clusters of cells were observed. This work provides insight for the design of a bionic liver microsystem.

CD14+ CD15- HLA-DR- myeloid-derived suppressor cells impair antimicrobial responses in patients with acute-on-chronic liver failure

OBJECTIVE

Immune paresis in patients with acute-on-chronic liver failure (ACLF) accounts for infection susceptibility and increased mortality. Immunosuppressive mononuclear CD14⁺HLA-DR^- myeloid-derived suppressor cells (M-MDSCs) have recently been identified to quell antimicrobial responses in immune-mediated diseases. We sought to delineate the function and derivation of M-MDSC in patients with ACLF, and explore potential targets to augment antimicrobial responses.

DESIGN

Patients with ACLF (n=41) were compared with healthy subjects (n=25) and patients with cirrhosis (n=22) or acute liver failure (n=30). CD14⁺CD15^-CD11b⁺HLA-DR^- cells were identified as per definition of M-MDSC and detailed immunophenotypic analyses were performed. Suppression of T cell activation was assessed by mixed lymphocyte reaction. Assessment of innate immune function included cytokine expression in response to Toll-like receptor (TLR-2, TLR-4 and TLR-9) stimulation and phagocytosis assays using flow cytometry and live cell imaging-based techniques.

RESULTS

Circulating CD14⁺CD15^-CD11b⁺HLA-DR^- M-MDSCs were markedly expanded in patients with ACLF (55% of CD14+ cells). M-MDSC displayed immunosuppressive properties, significantly decreasing T cell proliferation (p=0.01), producing less tumour necrosis factor-alpha/interleukin-6 in response to TLR stimulation (all p<0.01), and reduced bacterial uptake of Escherichia coli (p<0.001). Persistently low expression of HLA-DR during disease evolution was linked to secondary infection and 28-day mortality. Recurrent TLR-2 and TLR-4 stimulation expanded M-MDSC in vitro. By contrast, TLR-3 agonism reconstituted HLA-DR expression and innate immune function ex vivo.

CONCLUSION

Immunosuppressive CD14⁺HLA-DR^- M-MDSCs are expanded in patients with ACLF. They were depicted by suppressing T cell function, attenuated antimicrobial innate immune responses, linked to secondary infection, disease severity and prognosis. TLR-3 agonism reversed M-MDSC expansion and innate immune function and merits further evaluation as potential immunotherapeutic agent.

Paracetamol metabolism, hepatotoxicity, biomarkers and therapeutic interventions: a perspective

After over 60 years of therapeutic use in the UK, paracetamol (acetaminophen, N-acetyl-p-aminophenol, APAP) remains the subject of considerable research into both its mode of action and toxicity. The pharmacological properties of APAP are the focus of some activity, with the role of the metabolite N-arachidonoylaminophenol (AM404) still a topic of debate. However, that the hepatotoxicity of APAP results from the production of the reactive metabolite N-acetyl-p-benzoquinoneimine (NAPQI/NABQI) that can deplete glutathione, react with cellular macromolecules, and initiate cell death, is now beyond dispute. The disruption of cellular pathways that results from the production of NAPQI provides a source of potential biomarkers of the severity of the damage. Research in this area has provided new diagnostic markers such as the microRNA miR-122 as well as mechanistic biomarkers associated with apoptosis, mitochondrial dysfunction, inflammation and tissue regeneration. Additionally, biomarkers of, and systems biology models for, glutathione depletion have been developed. Furthermore, there have been significant advances in determining the role of both the innate immune system and genetic factors that might predispose individuals to APAP-mediated toxicity. This perspective highlights some of the progress in current APAP-related research.

MerTK expressing hepatic macrophages promote the resolution of inflammation in acute liver failure

OBJECTIVE

Acute liver failure (ALF) is characterised by overwhelming hepatocyte death and liver inflammation with massive infiltration of myeloid cells in necrotic areas. The mechanisms underlying resolution of acute hepatic inflammation are largely unknown. Here, we aimed to investigate the impact of Mer tyrosine kinase (MerTK) during ALF and also examine how the microenvironmental mediator, secretory leucocyte protease inhibitor (SLPI), governs this response.

DESIGN

Flow cytometry, immunohistochemistry, confocal imaging and gene expression analyses determined the phenotype, functional/transcriptomic profile and tissue topography of MerTK+ monocytes/macrophages in ALF, healthy and disease controls. The temporal evolution of macrophage MerTK expression and its impact on resolution was examined in APAP-induced acute liver injury using wild-type (WT) and Mer-deficient (Mer^-/-) mice. SLPI effects on hepatic myeloid cells were determined in vitro and in vivo using APAP-treated WT mice.

RESULTS

We demonstrate a significant expansion of resolution-like MerTK+HLA-DR^high cells in circulatory and tissue compartments of patients with ALF. Compared with WT mice which show an increase of MerTK+MHCII^high macrophages during the resolution phase in ALF, APAP-treated Mer^-/- mice exhibit persistent liver injury and inflammation, characterised by a decreased proportion of resident Kupffer cells and increased number of neutrophils. Both in vitro and in APAP-treated mice, SLPI reprogrammes myeloid cells towards resolution responses through induction of a MerTK+HLA-DR^high phenotype which promotes neutrophil apoptosis and their subsequent clearance.

CONCLUSIONS

We identify a hepatoprotective, MerTK+, macrophage phenotype that evolves during the resolution phase following ALF and represents a novel immunotherapeutic target to promote resolution responses following acute liver injury.

Assessment of immune organ dysfunction in critical illness: utility of innate immune response markers

In critically ill patients, organ dysfunctions are routinely assessed, monitored, and treated. Mounting data show that substantial critical illness-induced changes in the immune system can be observed in most ICU patients and that not only "hyper-inflammation" but also persistence of an anti-inflammatory phenotype (as in sepsis-associated immunosuppression) is associated with increased morbidity and mortality. Despite common perception, changes in functional immunity cannot be adequately assessed by routine inflammatory biomarkers such as C-reactive protein, procalcitonin, or numerical analysis of leukocyte (sub)-counts. Cytokines appear also not suited due to their short half-life and pleiotropy, their unexclusive origin from immune cells, and their potential to undergo antagonization by circulating inactivating molecules. Thus, beyond leukocyte quantification and use of routine biomarkers, direct assessment of immune cell function seems required to characterize the immune systems' status. This may include determination of, e.g., ex vivo cellular cytokine release, phagocytosis activity, and/or antigen-presenting capacity. In this regard, standardized flow-cytometric assessment of the major histocompatibility-II complex human leukocyte antigen (-D related) (HLA-DR) has gained particular interest. Monocytic HLA-DR (mHLA-DR) controls the interplay between innate and adaptive immunity and may serve as a "global" biomarker of injury-associated immunosuppression, and its decreased expression is associated with adverse clinical outcomes (e.g., secondary infection risk, mortality). Importantly, recent data demonstrate that injury-associated immunosuppression can be reversed-opening up new therapeutic avenues in affected patients. Here we discuss the potential scientific and clinical value of assessment of functional immunity with a focus on monocytes/macrophages and review the current state of knowledge and potential perspectives for affected critically ill patients.

慢加急性肝衰竭: 东西方诊断和预后的差异

慢加急性肝衰竭(acute-on-chronic liver failure, ACLF)是以慢性肝病基础上发生的急性肝功能失代偿和短期高死亡率为主要临床特征的一种可逆的、复杂的临床综合征. 由于不同区域ACLF的病因不同, 且病理机制复杂, 导致东西方对ACLF的定义及诊断标准仍存在争议, 且缺乏公认的预后评估体系. 近年来, ACLF引起了国内外学者的广泛关注, 取得了一些重要的研究进展, 本文将围绕国际上ACLF的最新进展, 对ACLF的定义及预后评估等进行分析总结.

Increased Expression of Cytotoxic T-Lymphocyte-Associated Protein 4 by T Cells, Induced by B7 in Sera, Reduces Adaptive Immunity in Patients With Acute Liver Failure

BACKGROUND & AIMS

Patients with acute liver failure (ALF) have defects in innate immune responses to microbes (immune paresis) and are susceptible to sepsis. Cytotoxic T-lymphocyte-associated protein 4 (CTLA4), which interacts with the membrane receptor B7 (also called CD80 and CD86), is a negative regulator of T-cell activation. We collected T cells from patients with ALF and investigated whether inhibitory signals down-regulate adaptive immune responses in patients with ALF.

METHODS

We collected peripheral blood mononuclear cells from patients with ALF and controls from September 2013 through September 2015 (45 patients with ALF, 20 patients with acute-on-chronic liver failure, 15 patients with cirrhosis with no evidence of acute decompensation, 20 patients with septic shock but no cirrhosis or liver disease, and 20 healthy individuals). Circulating CD4⁺ T cells were isolated and analyzed by flow cytometry. CD4⁺ T cells were incubated with antigen, or agonist to CD3 and dendritic cells, with or without antibody against CTLA4; T-cell proliferation and protein expression were quantified. We measured levels of soluble B7 molecules in supernatants of isolated primary hepatocytes, hepatic sinusoidal endothelial cells, and biliary epithelial cells from healthy or diseased liver tissues. We also measured levels of soluble B7 serum samples from patients and controls, and mice with acetaminophen-induced liver injury using enzyme-linked immunosorbent assays.

RESULTS

Peripheral blood samples from patients with ALF had a higher proportion of CD4⁺ CTLA4⁺ T cells than controls; patients with infections had the highest proportions. CD4⁺ T cells from patients with ALF had a reduced proliferative response to antigen or CD3 stimulation compared to cells from controls; incubation of CD4⁺ T cells from patients with ALF with an antibody against CTLA4 increased their proliferative response to antigen and to CD3 stimulation, to the same levels as cells from controls. CD4⁺ T cells from controls up-regulated expression of CTLA4 after 24-48 hours culture with sera from patients with ALF; these sera were found to have increased concentrations of soluble B7 compared to sera from controls. Necrotic human primary hepatocytes exposed to acetaminophen, but not hepatic sinusoidal endothelial cells and biliary epithelial cells from patients with ALF, secreted high levels of soluble B7. Sera from mice with acetaminophen-induced liver injury contained high levels of soluble B7 compared to sera from mice without liver injury. Plasma exchange reduced circulating levels of soluble B7 in patients with ALF and expression of CTLA4 on T cells.

CONCLUSIONS

Peripheral CD4⁺ T cells from patients with ALF have increased expression of CTLA4 compared to individuals without ALF; these cells have a reduced response to antigen and CD3 stimulation. We found sera of patients with ALF and from mice with liver injury to have high concentrations of soluble B7, which up-regulates CTLA4 expression by T cells and reduces their response to antigen. Plasma exchange reduces levels of B7 in sera from patients with ALF and might be used to restore antimicrobial responses to patients.

Mechanistic Modelling of Drug-Induced Liver Injury: Investigating the Role of Innate Immune Responses

Drug-induced liver injury (DILI) remains an adverse event of significant concern for drug development and marketed drugs, and the field would benefit from better tools to identify liver liabilities early in development and/or to mitigate potential DILI risk in otherwise promising drugs. DILIsym software takes a quantitative systems toxicology approach to represent DILI in pre-clinical species and in humans for the mechanistic investigation of liver toxicity. In addition to multiple intrinsic mechanisms of hepatocyte toxicity (ie, oxidative stress, bile acid accumulation, mitochondrial dysfunction), DILIsym includes the interaction between hepatocytes and cells of the innate immune response in the amplification of liver injury and in liver regeneration. The representation of innate immune responses, detailed here, consolidates much of the available data on the innate immune response in DILI within a single framework and affords the opportunity to systematically investigate the contribution of the innate response to DILI.

EASL Clinical Practical Guidelines on the management of acute (fulminant) liver failure

The term acute liver failure (ALF) is frequently applied as a generic expression to describe patients presenting with or developing an acute episode of liver dysfunction. In the context of hepatological practice, however, ALF refers to a highly specific and rare syndrome, characterised by an acute abnormality of liver blood tests in an individual without underlying chronic liver disease. The disease process is associated with development of a coagulopathy of liver aetiology, and clinically apparent altered level of consciousness due to hepatic encephalopathy. Several important measures are immediately necessary when the patient presents for medical attention. These, as well as additional clinical procedures will be the subject of these clinical practice guidelines.

Role of the inflammasome in acetaminophen-induced liver injury and acute liver failure

Drug-induced acute liver failure carries a high morbidity and mortality rate. Acetaminophen overdose is the number one cause of acute liver failure and remains a major problem in Western medicine. Administration of N-acetyl cysteine is an effective antidote when given before the initial rise in toxicity; however, many patients present to the hospital after this stage occurs. As such, treatments which can alleviate late-stage acetaminophen-induced acute liver failure are imperative. While the initial mechanisms of toxicity are well described, a debate has recently occurred in the literature over whether there is a second phase of injury, mediated by inflammatory processes. Critical to this potential inflammatory process is the activation of caspase-1 and interleukin-1β by a molecular complex known as the inflammasome. Several different stimuli for the formation of multiple different inflammasome complexes have been identified. Formation of the NACHT, leucine-rich repeat (LRR) and pyrin (PYD) domains-containing protein 3 (Nalp3) inflammasome in particular, has directly been attributed to late-stage acetaminophen toxicity. In this review, we will discuss the mechanisms of acetaminophen-induced liver injury in mice and man with a particular focus on the role of inflammation and the inflammasome.

Liver macrophages in tissue homeostasis and disease

Macrophages represent a key cellular component of the liver, and are essential for maintaining tissue homeostasis and ensuring rapid responses to hepatic injury. Our understanding of liver macrophages has been revolutionized by the delineation of heterogeneous subsets of these cells. Kupffer cells are a self-sustaining, liver-resident population of macrophages and can be distinguished from the monocyte-derived macrophages that rapidly accumulate in the injured liver. Specific environmental signals further determine the polarization and function of hepatic macrophages. These cells promote the restoration of tissue integrity following liver injury or infection, but they can also contribute to the progression of liver diseases, including hepatitis, fibrosis and cancer. In this Review, we highlight novel findings regarding the origin, classification and function of hepatic macrophages, and we discuss their divergent roles in the healthy and diseased liver.

Defective monocyte oxidative burst predicts infection in alcoholic hepatitis and is associated with reduced expression of NADPH oxidase

OBJECTIVE

In order to explain the increased susceptibility to serious infection in alcoholic hepatitis, we evaluated monocyte phagocytosis, aberrations of associated signalling pathways and their reversibility, and whether phagocytic defects could predict subsequent infection.

DESIGN

Monocytes were identified from blood samples of 42 patients with severe alcoholic hepatitis using monoclonal antibody to CD14. Phagocytosis and monocyte oxidative burst (MOB) were measured ex vivo using flow cytometry, luminometry and bacterial killing assays. Defects were related to the subsequent development of infection. Intracellular signalling pathways were investigated using western blotting and PCR. Interferon-γ (IFN-γ) was evaluated for its therapeutic potential in reversing phagocytic defects. Paired longitudinal samples were used to evaluate the effect of in vivo prednisolone therapy.

RESULTS

MOB, production of superoxide and bacterial killing in response to Escherichia coli were markedly impaired in patients with alcoholic hepatitis. Pretreatment MOB predicted development of infection within two weeks with sensitivity and specificity that were superior to available clinical markers. Accordingly, defective MOB was associated with death at 28 and 90 days. Expression of the gp91 ^phox subunit of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase was reduced in patients with alcoholic hepatitis demonstrating defective MOB. Monocytes were refractory to IFN-γ stimulation and showed high levels of a negative regulator of cytokine signalling, suppressor of cytokine signalling-1. MOB was unaffected by 7 days in vivo prednisolone therapy.

CONCLUSIONS

Monocyte oxidative burst and bacterial killing is impaired in alcoholic hepatitis while bacterial uptake by phagocytosis is preserved. Defective MOB is associated with reduced expression of NADPH oxidase in these patients and predicts the development of infection and death.

The impact of sterile inflammation in acute liver injury

BACKGROUND

The liver has a number of functions in innate immunity. These functions predispose the liver to innate immune-mediated liver injury when inflammation goes unchecked. Significant progress has been made in the last 25 years on sterile inflammatory liver injury in a number of models; however, a great deal of controversy and many questions about the nature of sterile inflammation still exist.

AIM

The goal of this article is to review sterile inflammatory liver injury using both a basic approach to what constitutes the inflammatory injury, and through examination of current models of liver injury and inflammation. This information will be tied to human patient conditions when appropriate.

RELEVANCE FOR PATIENTS

Inflammation is one of the most critical factors for managing in-patient liver disease in a number of scenarios. More information is needed for both scientists and clinicians to develop rational treatments.